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Sample records for cross flow filter

  1. Hot gas cross flow filtering module

    DOEpatents

    Lippert, Thomas E.; Ciliberti, David F.

    1988-01-01

    A filter module for use in filtering particulates from a high temperature gas has a central gas duct and at least one horizontally extending support mount affixed to the duct. The support mount supports a filter element thereon and has a chamber therein, which communicates with an inner space of the duct through an opening in the wall of the duct, and which communicates with the clean gas face of the filter element. The filter element is secured to the support mount over an opening in the top wall of the support mount, with releasable securement provided to enable replacement of the filter element when desired. Ceramic springs may be used in connection with the filter module either to secure a filter element to a support mount or to prevent delamination of the filter element during blowback.

  2. Method of producing monolithic ceramic cross-flow filter

    DOEpatents

    Larsen, D.A.; Bacchi, D.P.; Connors, T.F.; Collins, E.L. III

    1998-02-10

    Ceramic filter of various configuration have been used to filter particulates from hot gases exhausted from coal-fired systems. Prior ceramic cross-flow filters have been favored over other types, but those previously have been assemblies of parts somehow fastened together and consequently subject often to distortion or delamination on exposure hot gas in normal use. The present new monolithic, seamless, cross-flow ceramic filters, being of one-piece construction, are not prone to such failure. Further, these new products are made by a novel casting process which involves the key steps of demolding the ceramic filter green body so that none of the fragile inner walls of the filter is cracked or broken. 2 figs.

  3. Method of producing monolithic ceramic cross-flow filter

    DOEpatents

    Larsen, David A.; Bacchi, David P.; Connors, Timothy F.; Collins, III, Edwin L.

    1998-01-01

    Ceramic filter of various configuration have been used to filter particulates from hot gases exhausted from coal-fired systems. Prior ceramic cross-flow filters have been favored over other types, but those previously horn have been assemblies of parts somehow fastened together and consequently subject often to distortion or delamination on exposure hot gas in normal use. The present new monolithic, seamless, cross-flow ceramic filters, being of one-piece construction, are not prone to such failure. Further, these new products are made by novel casting process which involves the key steps of demolding the ceramic filter green body so that none of the fragile inner walls of the filter is cracked or broken.

  4. Development of a monolithic ceramic cross flow filter

    SciTech Connect

    Larsen, D.A.

    1995-12-01

    High-temperature, high-pressure particulate control is required to protect turbine equipment and to meet environmental stack emissions standards in coal-fueled power systems. Ceramic cross flow filters have high surface area per unit volume for removing particulates from these hot gas streams. A one-piece monolithic ceramic cross flow filter is needed. Mullite bonded, porous, permeable alumina ceramics were made on a lab scale with the Blasch injection forming process. Permeability and other initial targeted property requirements were achieved: >200 cd (<1 iwg/fpm), room temperature modulus of rupture >1000 psi, particle size 100/200 mesh, pore size 20 microns. It is concluded that it is feasible to use the proprietary Blasch process to form cross flow filters.

  5. Cross flow filter for AEPSC: TIDD slipstream HGCU project preliminary design package for Westinghouse cross flow filter system

    SciTech Connect

    Haldipur, G.B.; Lippert, T.E.

    1989-06-16

    The Westinghouse ceramic cross-flow filter element is constructed of multiple layers of thin, porous ceramic plates that contain ribs to form gas flow channels. Consecutive layers of the ceramic plates are oriented such that the channels of alternating plates are at an angle of 90 degrees ( cross flow'') to each other. The current size of a ceramic cross flow filter element is 12 in. {times} 12 in. {times} 14 in. Both sides of the short channels (4 in.) are exposed to the particle-laden coal gas. One end of the long (12 in.) channels is sealed while the other end of the long channel is mounted to the clean gas plenum. The particle-laden coal gas flows through the roof and floor'' of the porous ceramic plates that comprise the short, dirty side'' channels. The gas flows through the porous plates to the long, clean side'' channels. The gas flows through the porous plates to the long, clean side'' channels and finally to the clean gas plenum. The dust cake on the dirty side'' channels is periodically removed by applying a high-pressure reverse pulse of dry, clean gas through the clean gas plenum. For the TIDD plant filter slipstream, air will be utilized for filter cleaning.

  6. Cross flow filter for AEPSC: TIDD slipstream HGCU project preliminary design package for Westinghouse cross flow filter system. Final submittal

    SciTech Connect

    Haldipur, G.B.; Lippert, T.E.

    1989-06-16

    The Westinghouse ceramic cross-flow filter element is constructed of multiple layers of thin, porous ceramic plates that contain ribs to form gas flow channels. Consecutive layers of the ceramic plates are oriented such that the channels of alternating plates are at an angle of 90 degrees (``cross flow``) to each other. The current size of a ceramic cross flow filter element is 12 in. {times} 12 in. {times} 14 in. Both sides of the short channels (4 in.) are exposed to the particle-laden coal gas. One end of the long (12 in.) channels is sealed while the other end of the long channel is mounted to the clean gas plenum. The particle-laden coal gas flows through the ``roof and floor`` of the porous ceramic plates that comprise the short, ``dirty side`` channels. The gas flows through the porous plates to the long, ``clean side`` channels. The gas flows through the porous plates to the long, ``clean side`` channels and finally to the clean gas plenum. The dust cake on the ``dirty side`` channels is periodically removed by applying a high-pressure reverse pulse of dry, clean gas through the clean gas plenum. For the TIDD plant filter slipstream, air will be utilized for filter cleaning.

  7. Design and Initial Development of Monolithic Cross-Flow Ceramic Hot-Gas Filters

    SciTech Connect

    Barra, C.; Limaye, S.; Stinton, D.P.; Vaubert, V.M.

    1999-06-06

    Advanced, coal-fueled, power generation systems utilizing pressurized fluidized bed combustion (PFBC) and integrated gasification combined cycle (IGCC) technologies are currently being developed for high-efficiency, low emissions, and low-cost power generation. In spite of the advantages of these promising technologies, the severe operating environment often leads to material degradation and loss of performance in the barrier filters used for particle entrapment. To address this problem, LoTEC Inc., and Oak Ridge National Laboratory are jointly designing and developing a monolithic cross-flow ceramic hot-gas filter. The filter concept involves a truly monolithic cross-flow design that is resistant to delamination, can be easily fabricated, and offers flexibility of geometry and material make-up. During Phase I of the program, a thermo-mechanical analysis was performed to determine how a cross-flow filter would respond both thermally and mechanically to a series of thermal and mechanical loads. The cross-flow filter mold was designed accordingly, and the materials selection was narrowed down to Ca{sub 0.5}Sr{sub 0.5}Zr{sub 4}P{sub 6}O{sub 24} (CS-50) and 2Al{sub 2}O{sub 3}-3SiO{sub 2} (mullite). A fabrication process was developed using gelcasting technology and monolithic cross-flow filters were fabricated. The program focuses on obtaining optimum filter permeability and testing the corrosion resistance of the candidate materials.

  8. Thermal/chemical degradation of ceramic cross-flow filter materials

    SciTech Connect

    Alvin, M.A.; Lane, J.E.; Lippert, T.E.

    1989-11-01

    This report summarizes the 14-month, Phase 1 effort conducted by Westinghouse on the Thermal/Chemical Degradation of Ceramic Cross-Flow Filter Materials program. In Phase 1 expected filter process conditions were identified for a fixed-bed, fluid-bed, and entrained-bed gasification, direct coal fired turbine, and pressurized fluidized-bed combustion system. Ceramic cross-flow filter materials were also selected, procured, and subjected to chemical and physical characterization. The stability of each of the ceramic cross-flow materials was assessed in terms of potential reactions or phase change as a result of process temperature, and effluent gas compositions containing alkali and fines. In addition chemical and physical characterization was conducted on cross-flow filters that were exposed to the METC fluid-bed gasifier and the New York University pressurized fluidized-bed combustor. Long-term high temperature degradation mechanisms were proposed for each ceramic cross-flow material at process operating conditions. An experimental bench-scale test program is recommended to be conducted in Phase 2, generating data that support the proposed cross-flow filter material thermal/chemical degradation mechanisms. Papers on the individual subtasks have been processed separately for inclusion on the data base.

  9. Performance evaluation of a ceramic cross-flow filter on a bench-scale coal gasifier

    SciTech Connect

    Ciliberti, D.F.; Lippert, T.E.

    1985-01-01

    The Department of Energy is currently sporting a program that will aid in the development of cross flow filtration technology as applied to combined cycle power generation with coal gasification. The stated overall goal is to gain information on both the operational and economic feasibility of the implementation of cross flow filtration in various gasifier options. Westinghouse has prepared a comprehensive program that will lead directly to these program goals in an efficient manner. the proposed program is composed of three major technical task. Task 1 is directed at the design and actual test of a cross flow filter at a DOE bench scale gasifier. Task 2 is composed of several smaller theoretical and experimental efforts that are intended to firm up areas where engineering and design principles are lacking or considered inadequate. The third task is intended to integrate the results of the first two tasks in a conceptual design and cost analysis such that proper economic perspective for the filter concept can be gained. A brief summary of the approach taken in the technical tasks is presented in the following discussion.

  10. Performance evaluation of a ceramic cross-flow filter on a bench-scale coal gasifier

    SciTech Connect

    Ciliberti, D.F.; Lippert, T.E.

    1985-01-01

    The Department of Energy is currently supporting a program that will aid in the development of cross flow filtration technology as applied to combined cycle power generation with coal gasification. The stated overall goal is to gain information on both the operational and economic feasibility of the implementation of cross flow filtration in various gasifier options. Westinghouse has prepared a comprehensive program that will lead directly to these program goals in an efficient manner. The proposed program is composed of three major technical tasks. Task 1 is directed at the design and actual test of a cross flow filter at a DOE bench scale gasifier. Task 2 is composed of several smaller theoretical and experimental efforts that are intended to firm up areas where engineering and design principles are lacking or considered inadequate. The third task is intended to integrate the results of the first two tasks in a conceptual design and cost analysis such that proper economic perspective for the filter concept can be gained. A brief summary of the approach taken in the technical tasks is presented in the following discussion.

  11. Performance evaluation of a ceramic cross-flow filter on a bench- scale coal gasifier

    SciTech Connect

    Ciliberti, D.F.; Lippert, T.E.

    1985-01-01

    The Department of Energy is currently supporting a program that will aid in the development of cross flow filtration technology as applied to combined cycle power generation with coal gasification. The stated overall goal is to gain information on both the operational and economic feasibility of the implementation of cross flow filtration in various gasifier options. Westinghouse has prepared a comprehensive program that will lead directly to these program goals in an efficient manner. The proposed program is composed of three major technical tasks. Task 1 is directed at the design and actual test of a cross flow filter at a DOE bench scale gasifier. Task 2 is composed of several smaller theoretical and experimental efforts that are intended to firm up areas where engineering and design principles are lacking or considered inadequate. The third task is intended to integrate the results of the first two tasks in a conceptual design and cost analysis such that proper economic perspective for the filter concept can be gained. A brief summary of the approach taken in the technical tasks is presented in the following discussion. (VC)

  12. Cross-flow, filter-sorbent catalyst for particulate, SO sub 2 and NO sub x control

    SciTech Connect

    Not Available

    1990-03-01

    This synopsis describes a new concept for integrated pollutant control: a cross-flow filter comprised of layered, gas permeable membranes that act as a particulate filter, an SO{sub 2} sorbent, and a NO{sub x} reduction catalyst.

  13. Long-term durability testing of ceramic cross-flow filter. Final report, September 29, 1987--December 31, 1992

    SciTech Connect

    Lippert, T.E.; Smeltzer, E.E.; Alvin, M.A.; Bachovchin, D.M.

    1993-08-01

    Long term durability testing of the cross flow filter is described. Two high temperature, high pressure test facilities were built and operated. The facilities were designed to simulate dirty gas environments typical of Pressurized Fluidized Bed Combustion (PFBC) and coal gasification. Details of the design and operation of the test facilities and filter testing results are described.

  14. Performance evaluation of a ceramic cross-flow filter on a bench-scale coal gasifier, Volume 2

    SciTech Connect

    Lippert, T.E.; Bachovchin, D.M.; Smeltzer, E.E.; Meyer, J.H.; Vidt, E.J.

    1989-09-01

    This final report describes work conducted on the development of the ceramic cross flow filter for high temperature gas cleaning. This work was conducted from October 1984 through December 1988. Volume 1 provides an overall discussion of the program results. Volume 2 consists of Appendices that are referenced in Volume 1. Electricity costs, flow diagrams of the gasifier, and a model which describes the cleaning of the filter is included.

  15. Chemical cleaning of porous stainless steel cross-flow filter elements for nuclear waste applications

    SciTech Connect

    Billing, Justin M.; Daniel, Richard C.; Hallen, Richard T.; Schonewill, Philip P.; Shimskey, Rick W.; Peterson, Reid A.

    2011-05-10

    The Waste Treatment and Immobilization Plant (WTP) currently under construction for treatment of High-Level Waste (HLW) at the Hanford Site will rely on cross-flow ultrafiltration to provide solids-liquid separation as a core part of the treatment process. To optimize process throughput, periodic chemical cleaning of the porous stainless steel filter elements has been incorporated into the design of the plant. It is currently specified that chemical cleaning with nitric acid will occur after significant irreversible membrane fouling is observed. Irreversible fouling is defined as fouling that cannot be removed by backpulsing the filter. PNNL has investigated chemical cleaning processes as part of integrated tests with HLW simulants and with actual Hanford tank wastes. To quantify the effectiveness of chemical cleaning, the residual membrane resistance after cleaning was compared against the initial membrane resistance for each test in a series of long-term fouling tests. The impact of the small amount of residual resistance in these tests could not be separated from other parameters and the historical benchmark of >1 GPM/ft2 for clean water flux was determined to be an adequate metric for chemical cleaning. Using the results from these tests, a process optimization strategy is presented suggesting that for the simulant material under test, the value of chemical cleaning may be suspect. The period of enhanced filtration may not be enough to offset the down time required for chemical cleaning, without respect to the other associated costs.

  16. Subpilot scale gasifier evaluation of ceramic cross flow filter. Final report, February 1, 1988--December 31, 1992

    SciTech Connect

    Lippert, T.E.; Alvin, M.A.; Smeltzer, E.E.; Bachovchin, D.M.; Meyer, J.H.

    1993-08-01

    The operating characteristics, performance and durability of a hot gas cross flow filter system were evaluated at the Texaco 15 tpd, entrained-bed gasifier pilot plant facility that is located at their Montebello Research Facilities (MRL) in California. A candle filter unit was also tested for comparative purposes. A wide range of operating test conditions were experienced. This report summarizes the results of eleven different test runs that occurred from April 1989 through August 1992. Differences between filter operation on the entrained gasifier and prior experience on fluid bed combustion are discussed.

  17. Performance evaluation of a ceramic cross-flow filter on a bench-scale coal gasifier

    SciTech Connect

    Lippert, T.E.; Bachovchin, D.M.; Smeltzer, E.E.; Meyer, J.H.; Vidt, E.J.

    1989-09-01

    The ceramic cross-flow filter (CXF) system is a promising method to be used in advanced coal based power systems for high temperature, high pressure (HTHP) particle removal. Using a subpilot scale pressurized fluid-bed combustor (PFBC) at Argonne National Laboratory and various PFBC simulators, prior projects have indicated that CXF systems can be used in oxidizing environments at PFBC conditions. To extend the use of CXF systems, this project completed an economic analysis comparing the cost of various oxygen and air blown gasification systems with the CXF system incorporated, initiated the scaleup of the CXF element from development to commercial size, predicted the characteristics of gasifier dust cake, evaluated cleaning pulse characteristics in a large multielement simulation, upgraded pulse cleaning mathematical model, and completed additional testing of the CXF elements under gasification (reducing) and PFBC conditions. Coors Ceramic Company and GTE Products Corporation were integrally involved in this program through the development and fabrication of the CXF elements. 39 figs., 23 tabs.

  18. Hot gas cleanup using ceramic cross flow membrane filters. Final report

    SciTech Connect

    Ciliberti, D.F.; Smeltzer, E.E.; Alvin, M.A.; Keairns, D.L.; Bachovchin, D.M.

    1983-12-01

    The single unresolved technical issue in the commercialization of pressurized fluid-bed combustion (PPBC) for electric power production is the hot gas cleaning problem. In this technology, high-temperature and -pressure (HTHP), dust-laden flue gases from the combustor must be cleaned enough to reduce expansion turbine blade erosion to an economically acceptable level. Additionally, the level of particulate emission must be compatible with the New Source Performance Standards (NSPS) for environmental acceptability. The Department of Energy (DOE) has sponsored a wide range of research and development programs directed at the solution of this problem. These programs were divided into two classifications, one dealing with more advanced concepts where testing was to be done at relatively large scale and a second group of less advanced, novel concepts where the testing was to be carried out at a bench scale. The cross-flow ceramic membrane filter program described in this report is a member of the small-scale, novel concept group.

  19. Performance evaluation of a ceramic cross-flow filter on a bench- scale coal gasifier

    SciTech Connect

    Ciliberti, D.F.; Lippert, T.E.

    1985-01-01

    The Department of Energy is currently supporting a program that will aid in the development of cross flow filtration technology as applied to combined cycle power generation with coal gasification. The stated overall goal is to gain information on both the operational and economic feasibility of the implementation of cross flow filtration in various gasifier options. Westinghouse has prepared a comprehensive program that will lead directly to these program goals in an efficient manner.

  20. Performance evaluation of a ceramic cross-flow filter on a bench- scale coal gasifier

    SciTech Connect

    Ciliberti, D.F.; Lippert, T.E.

    1984-01-01

    The Department of Energy is currently supporting a program that will aid in the development of cross flow filtration technology as applied to combined cycle power generation with coal gasification. The stated overall goal is to gain information on both the operational and economic feasibility of the implementation of cross flow filtration in various gasifier options. Westinghouse has prepared a comprehensive program that will lead directly to these program goals in an efficient manner.

  1. Performance evaluation of a ceramic cross-flow filter on a bench- scale coal gasifier

    SciTech Connect

    Ciliberti, D.F.; Lippert, T.E.

    1986-01-01

    The Department of Energy is currently supporting a program that will aid in the development of cross flow filtration technology as applied to combined cycle power generation with coal gasification. The stated overall goal is to gain information on both the operational and economic feasibility of the implementation of cross flow filtration in various gasifier options. Westinghouse has prepared a comprehensive program that will lead directly to these program goals in an efficient manner.

  2. [Performance of cross flow trickling filter for H2S gas treatment].

    PubMed

    Liu, Chun-Jing; Li, Jian; Liu, Jia; Peng, Shu-Jing; Li, Chao; Chen, Ying; He, Hong

    2012-09-01

    A grading cross bio-trickling filter was designed for H2S removal. Mixed microorganisms domesticated from the former experiment were immobilized to start up the trickling filter. Removal performances during starting up period and different loadings were investigated. Results showed that the immobilization of the trickling filter was completed within 3 d. The removal efficiency was higher than 99% when the inlet concentration was in the range of 110 mg x m(-3) to 230 mg x m(-3) (EBRT 30 s). At low inlet loadings, the front part of the trickling filter played a major role in H2S degradation, accounting for about 85%. Microbial diversity and population of the front part were superior to the tail one. At higher loadings, microbial diversity and population of the tail part increased significantly, from 4.5 x 10(7) cells x g (-1) to 5.17 x 10(8) cells x g(-1), and the elimination capacity was also improved,from 0.04 g x h(-1) to 0.67 g x h(-1). Rod-shaped bacteria were the dominant microorganisms on the surface of ceramics in the steady state as observed by SEM. The surfaces of ceramics were covered by a lot of microbial metabolites at high loadings. Analysis of the metabolites indicated that the majority of H2S was oxidized to sulfur and only a small portion was converted to sulfate.

  3. Concentric Split Flow Filter

    NASA Technical Reports Server (NTRS)

    Stapleton, Thomas J. (Inventor)

    2015-01-01

    A concentric split flow filter may be configured to remove odor and/or bacteria from pumped air used to collect urine and fecal waste products. For instance, filter may be designed to effectively fill the volume that was previously considered wasted surrounding the transport tube of a waste management system. The concentric split flow filter may be configured to split the air flow, with substantially half of the air flow to be treated traveling through a first bed of filter media and substantially the other half of the air flow to be treated traveling through the second bed of filter media. This split flow design reduces the air velocity by 50%. In this way, the pressure drop of filter may be reduced by as much as a factor of 4 as compare to the conventional design.

  4. Cross-flow, filter-sorbent catalyst for particulate, SO{sub 2} and NO{sub x} control. First quarterly technical progress report, 1990

    SciTech Connect

    Not Available

    1990-03-01

    This synopsis describes a new concept for integrated pollutant control: a cross-flow filter comprised of layered, gas permeable membranes that act as a particulate filter, an SO{sub 2} sorbent, and a NO{sub x} reduction catalyst.

  5. Performance evaluation of a ceramic cross-flow filter on a bench- scale coal gasifier. Second quarterly project report, January 1, 1985--March 31, 1985

    SciTech Connect

    Ciliberti, D.F.; Lippert, T.E.

    1985-12-31

    The Department of Energy is currently supporting a program that will aid in the development of cross flow filtration technology as applied to combined cycle power generation with coal gasification. The stated overall goal is to gain information on both the operational and economic feasibility of the implementation of cross flow filtration in various gasifier options. Westinghouse has prepared a comprehensive program that will lead directly to these program goals in an efficient manner. The proposed program is composed of three major technical tasks. Task 1 is directed at the design and actual test of a cross flow filter at a DOE bench scale gasifier. Task 2 is composed of several smaller theoretical and experimental efforts that are intended to firm up areas where engineering and design principles are lacking or considered inadequate. The third task is intended to integrate the results of the first two tasks in a conceptual design and cost analysis such that proper economic perspective for the filter concept can be gained. A brief summary of the approach taken in the technical tasks is presented in the following discussion. (VC)

  6. Performance evaluation of a ceramic cross-flow filter on a bench-scale coal gasifier. Fifth quarterly report, October 1, 1985--December 31, 1985

    SciTech Connect

    Ciliberti, D.F.; Lippert, T.E.

    1985-12-31

    The Department of Energy is currently sporting a program that will aid in the development of cross flow filtration technology as applied to combined cycle power generation with coal gasification. The stated overall goal is to gain information on both the operational and economic feasibility of the implementation of cross flow filtration in various gasifier options. Westinghouse has prepared a comprehensive program that will lead directly to these program goals in an efficient manner. the proposed program is composed of three major technical task. Task 1 is directed at the design and actual test of a cross flow filter at a DOE bench scale gasifier. Task 2 is composed of several smaller theoretical and experimental efforts that are intended to firm up areas where engineering and design principles are lacking or considered inadequate. The third task is intended to integrate the results of the first two tasks in a conceptual design and cost analysis such that proper economic perspective for the filter concept can be gained. A brief summary of the approach taken in the technical tasks is presented in the following discussion.

  7. Performance evaluation of a ceramic cross-flow filter on a bench-scale coal gasifier. Fourth quarterly report, July 1, 1985--September 30, 1985

    SciTech Connect

    Ciliberti, D.F.; Lippert, T.E.

    1985-12-31

    The Department of Energy is currently supporting a program that will aid in the development of cross flow filtration technology as applied to combined cycle power generation with coal gasification. The stated overall goal is to gain information on both the operational and economic feasibility of the implementation of cross flow filtration in various gasifier options. Westinghouse has prepared a comprehensive program that will lead directly to these program goals in an efficient manner. The proposed program is composed of three major technical tasks. Task 1 is directed at the design and actual test of a cross flow filter at a DOE bench scale gasifier. Task 2 is composed of several smaller theoretical and experimental efforts that are intended to firm up areas where engineering and design principles are lacking or considered inadequate. The third task is intended to integrate the results of the first two tasks in a conceptual design and cost analysis such that proper economic perspective for the filter concept can be gained. A brief summary of the approach taken in the technical tasks is presented in the following discussion.

  8. Compact bypass-flow filter

    NASA Technical Reports Server (NTRS)

    Swift, W. G.; Ulanovsky, J. M.

    1979-01-01

    Annular filter consisting of stacked rings separates particulates from bypass fluid passing through it in radial direction without slowing down main flow across unimpeded flow of fluid through its center. Applications include fluidized bed reactors, equipment for catalyst operations, and water purification.

  9. DEMONSTRATION BULLETIN: COLLOID POLISHING FILTER METHOD - FILTER FLOW TECHNOLOGY, INC.

    EPA Science Inventory

    The Filter Flow Technology, Inc. (FFT) Colloid Polishing Filter Method (CPFM) was tested as a transportable, trailer mounted, system that uses sorption and chemical complexing phenomena to remove heavy metals and nontritium radionuclides from water. Contaminated waters can be pro...

  10. Method and apparatus for measuring flow velocity using matched filters

    DOEpatents

    Raptis, A.C.

    1983-09-06

    An apparatus and method for measuring the flow velocities of individual phase flow components of a multiphase flow utilizes matched filters. Signals arising from flow noise disturbance are extracted from the flow, at upstream and downstream locations. The signals are processed through pairs of matched filters which are matched to the flow disturbance frequency characteristics of the phase flow component to be measured. The processed signals are then cross-correlated to determine the transit delay time of the phase flow component between sensing positions. 8 figs.

  11. Method and apparatus for measuring flow velocity using matched filters

    DOEpatents

    Raptis, Apostolos C.

    1983-01-01

    An apparatus and method for measuring the flow velocities of individual phase flow components of a multiphase flow utilizes matched filters. Signals arising from flow noise disturbance are extracted from the flow, at upstream and downstream locations. The signals are processed through pairs of matched filters which are matched to the flow disturbance frequency characteristics of the phase flow component to be measured. The processed signals are then cross-correlated to determine the transit delay time of the phase flow component between sensing positions.

  12. Performance evaluation of a ceramic cross-flow filter on a bench- scale coal gasifier. Sixth quarterly report, January 1, 1986--March 31, 1986

    SciTech Connect

    Ciliberti, D.F.; Lippert, T.E.

    1986-12-31

    The Department of Energy is currently supporting a program that will aid in the development of cross flow filtration technology as applied to combined cycle power generation with coal gasification. The stated overall goal is to gain information on both the operational and economic feasibility of the implementation of cross flow filtration in various gasifier options. Westinghouse has prepared a comprehensive program that will lead directly to these program goals in an efficient manner.

  13. Performance evaluation of a ceramic cross-flow filter on a bench- scale coal gasifier. First quarterly project report, October 1, 1984--December 31, 1984

    SciTech Connect

    Ciliberti, D.F.; Lippert, T.E.

    1984-12-31

    The Department of Energy is currently supporting a program that will aid in the development of cross flow filtration technology as applied to combined cycle power generation with coal gasification. The stated overall goal is to gain information on both the operational and economic feasibility of the implementation of cross flow filtration in various gasifier options. Westinghouse has prepared a comprehensive program that will lead directly to these program goals in an efficient manner.

  14. Performance evaluation of a ceramic cross-flow filter on a bench- scale coal gasifier. Third quarterly report, April 1--June 30, 1985

    SciTech Connect

    Ciliberti, D.F.; Lippert, T.E.

    1985-12-31

    The Department of Energy is currently supporting a program that will aid in the development of cross flow filtration technology as applied to combined cycle power generation with coal gasification. The stated overall goal is to gain information on both the operational and economic feasibility of the implementation of cross flow filtration in various gasifier options. Westinghouse has prepared a comprehensive program that will lead directly to these program goals in an efficient manner.

  15. Granular flow in Dorfan Impingo filter for gas cleanup

    SciTech Connect

    Hsiau, S.S.; Smid, J.; Tsai, H.H.; Kuo, J.T.; Chou, C.S.

    1999-07-01

    Inside a two-dimensional model of the louvered Drofan Impingo panel with transparent front and rear walls, the velocity fields of filter granules without gas cross flow were observed. The PE beads with diameter of 6 mm were used as filter granules. The filter bed was filled with beads continuously and circulated until the granular flows inside the panel reached the steady state condition. In the moving granular bed, there is a central fast flowing core of filter granules surrounded by large quasi-stagnant zones located close to the louver walls. The existence of quasi-stagnant zones may result in the dust plugging problems. The velocity fields of filter granules are plotted for three different louver geometries.

  16. A Filtering Method For Gravitationally Stratified Flows

    SciTech Connect

    Gatti-Bono, Caroline; Colella, Phillip

    2005-04-25

    Gravity waves arise in gravitationally stratified compressible flows at low Mach and Froude numbers. These waves can have a negligible influence on the overall dynamics of the fluid but, for numerical methods where the acoustic waves are treated implicitly, they impose a significant restriction on the time step. A way to alleviate this restriction is to filter out the modes corresponding to the fastest gravity waves so that a larger time step can be used. This paper presents a filtering strategy of the fully compressible equations based on normal mode analysis that is used throughout the simulation to compute the fast dynamics and that is able to damp only fast gravity modes.

  17. Spin selective filtering of polariton condensate flow

    SciTech Connect

    Gao, T.; Antón, C.; Martín, M. D.; Liew, T. C. H.; Hatzopoulos, Z.; Viña, L.; Eldridge, P. S.; Savvidis, P. G.

    2015-07-06

    Spin-selective spatial filtering of propagating polariton condensates, using a controllable spin-dependent gating barrier, in a one-dimensional semiconductor microcavity ridge waveguide is reported. A nonresonant laser beam provides the source of propagating polaritons, while a second circularly polarized weak beam imprints a spin dependent potential barrier, which gates the polariton flow and generates polariton spin currents. A complete spin-based control over the blocked and transmitted polaritons is obtained by varying the gate polarization.

  18. Cross-flow, filter-sorbent-catalyst for particulate, SO{sub 2} and NO{sub x} control. Final report

    SciTech Connect

    Benedek, K.; Flytzani-Stephanopoulos, M.

    1994-05-01

    This report describes work performed on a new concept for integrated pollutant control: An active filter comprised of layered, gas permeable membranes that act as a particle filter, an SO{sub 2} sorbent, and a NO{sub x}, reduction catalyst. The focus of the research program documented in this final report is the development of the sorbent/catalyst materials that are the basis of such an emission control system. The device investigated in this program will simultaneously remove particulates, SO{sub 2} and NO{sub x}, from combustion exhaust gases. Sulfur dioxide capture and nitrogen oxide reduction are achieved with a reg le, mixed-metal oxide sorbent-catalyst. The device is a filter with layered walls: A small-pore layer is a barrier to particles, and a macroporus active layer is a SO{sub 2} sorbent and a catalyst for the selective catalytic reduction of NO{sub x}. The small-pore layer could be an inert ceramic that provides structural strength to the unit and protects the active (sorbent-catalyst) material from abrasion or contamination from fly ash particles. We have found that 95--100% removal efficiency of SO{sub 2} and 60--90% removal of NO{sub x}, is achievable with the use of mixed-metal oxide sorbent-catalysts in the device. The ceramic filters are barriers to particles and typically have removal efficiencies of 99.9%.

  19. Flow regions of granules in Dorfan Impingo filter for gas cleanup

    SciTech Connect

    Kuo, J.T.; Smid, J.; Hsiau, S.S.; Tsai, S.S.; Chou, C.S.

    1999-07-01

    Inside a two-dimensional model of the louvered Dorfan Impingo panel with transparent front and rear walls the flow region of filter granules without gas cross flow were observed. The white PE beads were used as filter granules. Colored PE beads served as tracers. Filter granules were discharged and circulated to the bed. The flow rate of filter medium was controlled by the belt conveyor. The image processing system including a Frame Grabber and JVC videocamera was used to record the granular flow. Every image of motion was digitized and stored in a file. The flow patterns and the quasi-stagnant zones history in the moving granular bed were evaluated. The experiment showed fast central moving region (flowing core) of filter granules and quasi-stagnant zones close to louver walls.

  20. Modeling jets in cross flow

    NASA Technical Reports Server (NTRS)

    Demuren, A. O.

    1994-01-01

    Various approaches to the modeling of jets in cross flow are reviewed. These are grouped into four classes, namely: empirical models, integral models, perturbation models, and numerical models. Empirical models depend largely on the correlation of experimental data and are mostly useful for first-order estimates of global properties such as jet trajectory and velocity and temperature decay rates. Integral models are based on some ordinary-differential form of the conservation laws, but require substantial empirical calibration. They allow more details of the flow field to be obtained; simpler versions have to assume similarity of velocity and temperature profiles, but more sophisticated ones can actually calculate these profiles. Perturbation models require little empirical input, but the need for small parameters to ensure convergent expansions limits their application to either the near-field or the far-field. Therefore, they are mostly useful for the study of flow physics. Numerical models are based on conservation laws in partial-differential form. They require little empirical input and have the widest range of applicability. They also require the most computational resources. Although many qualitative and quantitative features of jets in cross flow have been predicted with numerical models, many issues affecting accuracy such as grid resolution and turbulence model are not completely resolved.

  1. Cross-flow Ultrafiltration Scaling Considerations

    SciTech Connect

    Duignan, M

    2006-04-10

    One legacy of the nuclear age is radioactive waste and it must be stabilized to be stored in a safe manner. An important part of the stabilization process is the separation of radioactive solids from the liquid wastes by cross-flow ultrafiltration. The performance of this technology with the wastes to be treated was unknown and, therefore, had to be obtained. However, before beginning a filter study the question of experimental scale had to be addressed. Of course, carrying out experiments using full-size equipment is always ideal, but rarely practical when dealing with plant size processes. Flow loops that will handle millions of liters of slurries, which are either highly caustic or acidic, with flow rates of 10,000 lpm make full-scale tests prohibitively expensive. Moreover, when the slurries happen to be radioactive such work is also very dangerous. All of these considerations lend themselves to investigations at smaller scales and in many situations can be treated with computational analyses. Unfortunately, as scale is reduced it becomes harder to provide prototypic results and the two and three phase multi-component mixtures challenge accurate computational results. To obtain accurate and representative filter results the use of two scales were chosen: (1) Small-scale--would allow the testing with actual radioactive waste samples and compare results with simulated wastes that were not radioactive. For this scale the feed tank held 6 liters of waste and it had a single cross-flow filter tube 0.61 m long. (2) Pilot-scale--would be restricted to use simulated non-radioactive wastes. At this larger scale the feed tank held 120 liters of waste and the filter unit was prototypic to the planned plant facility in pore size (0.1 micron), length (2.29 m), diameter (0.0127 m inside and 0.0159 m outside diameter), and being multi-tubed. The small-scale apparatus is convenient, easy to use, and can test both radioactive and non-radioactive wastes; therefore, there is a

  2. Laser cross-flow gas system

    DOEpatents

    Duncan, David B.

    1992-01-01

    A method and laser apparatus are disclosed which provide for a cross-flow of gas near one end of a laser discharge tube. The cross-flow of gas causes a concentration gradient which affects diffusion of contaminants in the discharge tube towards the cross-flow of the gas, which contaminants are then withdrawn from the discharge tube.

  3. Cross Flow Parameter Calculation for Aerodynamic Analysis

    NASA Technical Reports Server (NTRS)

    Norman, David, Jr. (Inventor)

    2014-01-01

    A system and method for determining a cross flow angle for a feature on a structure. A processor unit receives location information identifying a location of the feature on the structure, determines an angle of the feature, identifies flow information for the location, determines a flow angle using the flow information, and determines the cross flow angle for the feature using the flow angle and the angle of the feature. The flow information describes a flow of fluid across the structure. The flow angle comprises an angle of the flow of fluid across the structure for the location of the feature.

  4. Modeling Flow Past a Tilted Vena Cava Filter

    SciTech Connect

    Singer, M A; Wang, S L

    2009-06-29

    Inferior vena cava filters are medical devices used to prevent pulmonary embolism (PE) from deep vein thrombosis. In particular, retrievable filters are well-suited for patients who are unresponsive to anticoagulation therapy and whose risk of PE decreased with time. The goal of this work is to use computational fluid dynamics to evaluate the flow past an unoccluded and partially occluded Celect inferior vena cava filter. In particular, the hemodynamic response to thrombus volume and filter tilt is examined, and the results are compared with flow conditions that are known to be thrombogenic. A computer model of the filter inside a model vena cava is constructed using high resolution digital photographs and methods of computer aided design. The models are parameterized using the Overture software framework, and a collection of overlapping grids is constructed to discretize the flow domain. The incompressible Navier-Stokes equations are solved, and the characteristics of the flow (i.e., velocity contours and wall shear stresses) are computed. The volume of stagnant and recirculating flow increases with thrombus volume. In addition, as the filter increases tilt, the cava wall adjacent to the tilted filter is subjected to low velocity flow that gives rise to regions of low wall shear stress. The results demonstrate the ease of IVC filter modeling with the Overture software framework. Flow conditions caused by the tilted Celect filter may elevate the risk of intrafilter thrombosis and facilitate vascular remodeling. This latter condition also increases the risk of penetration and potential incorporation of the hook of the filter into the vena caval wall, thereby complicating filter retrieval. Consequently, severe tilt at the time of filter deployment may warrant early clinical intervention.

  5. Impinging jets in cross-flow

    NASA Astrophysics Data System (ADS)

    Knowles, K.; Bray, D.; Bailey, P. J.; Curtis, P.

    1992-02-01

    The present investigation of flowfields generated by the impingement of single and twin jets in cross-flows gives attention to the ground vortex position-defining parameters of cross-flow/nozzle velocities ratio, cross-flow boundary layer thickness, nozzle height, nozzle pressure ratio, vector angle, and nozzle splay (with both fixed and moving ground-planes). The results obtained indicate that the ground vortex moves away from the nozzle centerline as the ratio of cross-flow velocity to nozzle exit velocity is decreased. The positional rate of change, however, depends on other parameters. Self-similarity laws are proposed for the ground vortex and wall jet.

  6. Particle flow for nonlinear filters with log-homotopy

    NASA Astrophysics Data System (ADS)

    Daum, Fred; Huang, Jim

    2008-04-01

    We describe a new nonlinear filter that is vastly superior to the classic particle filter. In particular, the computational complexity of the new filter is many orders of magnitude less than the classic particle filter with optimal estimation accuracy for problems with dimension greater than 2 or 3. We consider nonlinear estimation problems with dimensions varying from 1 to 20 that are smooth and fully coupled (i.e. dense not sparse). The new filter implements Bayes' rule using particle flow rather than with a pointwise multiplication of two functions; this avoids one of the fundamental and well known problems in particle filters, namely "particle collapse" as a result of Bayes' rule. We use a log-homotopy to derive the ODE that describes particle flow. This paper was written for normal engineers, who do not have homotopy for breakfast.

  7. SITE TECHNOLOGY CAPSULE: FILTER FLOW TECHNOLOGY, INC. - COLLOID POLISHING FILTER METHOD

    EPA Science Inventory

    The Filter Flow Technology, Inc. (FFT) Coloid Polishing Filter Method (CPFM) was demonstrated at the U.S Department of Energy's (DOE) Rock Flats Plant (RFP) as part of the U.S. Environmental Protection Agency's (EPA) Superfund and Innovative Technology Evaluation (SITE) program. ...

  8. PERFORMANCE IMPROVEMENT OF CROSS-FLOW FILTRATION FOR HIGH LEVEL WASTE TREATMENT

    SciTech Connect

    Duignan, M.; Nash, C.; Poirier, M.

    2011-01-12

    In the interest of accelerating waste treatment processing, the DOE has funded studies to better understand filtration with the goal of improving filter fluxes in existing cross-flow equipment. The Savannah River National Laboratory (SRNL) was included in those studies, with a focus on start-up techniques, filter cake development, the application of filter aids (cake forming solid precoats), and body feeds (flux enhancing polymers). This paper discusses the progress of those filter studies. Cross-flow filtration is a key process step in many operating and planned waste treatment facilities to separate undissolved solids from supernate slurries. This separation technology generally has the advantage of self-cleaning through the action of wall shear stress created by the flow of waste slurry through the filter tubes. However, the ability of filter wall self-cleaning depends on the slurry being filtered. Many of the alkaline radioactive wastes are extremely challenging to filtration, e.g., those containing compounds of aluminum and iron, which have particles whose size and morphology reduce permeability. Unfortunately, low filter flux can be a bottleneck in waste processing facilities such as the Savannah River Modular Caustic Side Solvent Extraction Unit and the Hanford Waste Treatment Plant. Any improvement to the filtration rate would lead directly to increased throughput of the entire process. To date increased rates are generally realized by either increasing the cross-flow filter axial flowrate, limited by pump capacity, or by increasing filter surface area, limited by space and increasing the required pump load. SRNL set up both dead-end and cross-flow filter tests to better understand filter performance based on filter media structure, flow conditions, filter cleaning, and several different types of filter aids and body feeds. Using non-radioactive simulated wastes, both chemically and physically similar to the actual radioactive wastes, the authors performed

  9. Molecular Dynamics Simulation of a Microvillus in a Cross Flow

    NASA Astrophysics Data System (ADS)

    Chen, X. Y.; Liu, Y.; So, R. M. C.; Yang, J. M.

    One of the functions of microvilli in the microvessel endothelial glycocalyx is molecular filtering. The microvillus behaves as a mechanosensory system which may sense the fluid shear and drag forces. The permeability of small particles in microvessel is crucial for drug design and drug delivery. Therefore a better understanding of flow field around microvillus is important to simulate accurately the particle penetration in microvessel. Since the dimension of the microvilli is about ~10 nm, the conventional Navier-Stokes equation may not be good enough to simulate the fluid flow in such microscale and nanoscale structures. Molecular dynamics (MD) simulation is a powerful method to simulate the fluid flow at the molecular level. As a first attempt, the microvillus is reduced as a two-dimensional cylinder which is in a cross flow. The detailed drag and lift together with flow field are obtained and compared with available data.

  10. Cross-flow electrochemical reactor cells, cross-flow reactors, and use of cross-flow reactors for oxidation reactions

    DOEpatents

    Balachandran, Uthamalingam; Poeppel, Roger B.; Kleefisch, Mark S.; Kobylinski, Thaddeus P.; Udovich, Carl A.

    1994-01-01

    This invention discloses cross-flow electrochemical reactor cells containing oxygen permeable materials which have both electron conductivity and oxygen ion conductivity, cross-flow reactors, and electrochemical processes using cross-flow reactor cells having oxygen permeable monolithic cores to control and facilitate transport of oxygen from an oxygen-containing gas stream to oxidation reactions of organic compounds in another gas stream. These cross-flow electrochemical reactors comprise a hollow ceramic blade positioned across a gas stream flow or a stack of crossed hollow ceramic blades containing a channel or channels for flow of gas streams. Each channel has at least one channel wall disposed between a channel and a portion of an outer surface of the ceramic blade, or a common wall with adjacent blades in a stack comprising a gas-impervious mixed metal oxide material of a perovskite structure having electron conductivity and oxygen ion conductivity. The invention includes reactors comprising first and second zones seprated by gas-impervious mixed metal oxide material material having electron conductivity and oxygen ion conductivity. Prefered gas-impervious materials comprise at least one mixed metal oxide having a perovskite structure or perovskite-like structure. The invention includes, also, oxidation processes controlled by using these electrochemical reactors, and these reactions do not require an external source of electrical potential or any external electric circuit for oxidation to proceed.

  11. Electrically heated particulate filter with zoned exhaust flow control

    SciTech Connect

    Gonze, Eugene V

    2012-06-26

    A system includes a particulate matter (PM) filter that includes X zones. An electrical heater includes Y heater segments that are associated with respective ones of the X zones. The electrical heater is arranged upstream from and proximate with the PM filter. A valve assembly includes Z sections that are associated with respective ones of the X zones. A control module adjusts flow through each of the Z sections during regeneration of the PM filter via control of the valve assembly. X, Y and Z are integers.

  12. Direction of fluid flow and the properties of fibrous filters

    SciTech Connect

    Pich, J.; Spurny, K.

    1991-01-01

    The influence of the fluid flow direction (downflow and upflow) on the filtration properties of filters that have a fibrous structure is investigated. It is concluded that selectivity of these filters (dependence of the filter efficiency on the particle size) in the case of upflow is changed - in comparison with the case of downflow - in three ways: the position of the minimum of this dependence is shifted to larger particle sizes, and the whole selectivity is decreased and simultaneously deformed. Corresponding equations for this shift and changes are derived and analyzed. Theoretical predictions are compared with available experimental data. In all cases qualitative agreement and in some cases quantitative agreement is found.

  13. Absorption Filter Based Optical Diagnostics in High Speed Flows

    NASA Technical Reports Server (NTRS)

    Samimy, Mo; Elliott, Gregory; Arnette, Stephen

    1996-01-01

    Two major regimes where laser light scattered by molecules or particles in a flow contains significant information about the flow are Mie scattering and Rayleigh scattering. Mie scattering is used to obtain only velocity information, while Rayleigh scattering can be used to measure both the velocity and the thermodynamic properties of the flow. Now, recently introduced (1990, 1991) absorption filter based diagnostic techniques have started a new era in flow visualization, simultaneous velocity and thermodynamic measurements, and planar velocity measurements. Using a filtered planar velocimetry (FPV) technique, we have modified the optically thick iodine filter profile of Miles, et al., and used it in the pressure-broaden regime which accommodates measurements in a wide range of velocity applications. Measuring velocity and thermodynamic properties simultaneously, using absorption filtered based Rayleigh scattering, involves not only the measurement of the Doppler shift, but also the spectral profile of the Rayleigh scattering signal. Using multiple observation angles, simultaneous measurement of one component velocity and thermodynamic properties in a supersonic jet were measured. Presently, the technique is being extended for simultaneous measurements of all three components of velocity and thermodynamic properties.

  14. Filtering requirements for gradient-based optical flow measurement.

    PubMed

    Christmas, W J

    2000-01-01

    The accuracy of gradient-based optical flow algorithms depends on the ability to measure intensity gradients accurately. We show how the temporal gradient can be compromised by temporal aliasing arising from motion and how appropriate post-sampling spatial filtering improves the situation. We also demonstrate a benefit of using higher-order gradient estimators.

  15. Rating knowledge sharing in cross-domain collaborative filtering.

    PubMed

    Li, Bin; Zhu, Xingquan; Li, Ruijiang; Zhang, Chengqi

    2015-05-01

    Cross-domain collaborative filtering (CF) aims to share common rating knowledge across multiple related CF domains to boost the CF performance. In this paper, we view CF domains as a 2-D site-time coordinate system, on which multiple related domains, such as similar recommender sites or successive time-slices, can share group-level rating patterns. We propose a unified framework for cross-domain CF over the site-time coordinate system by sharing group-level rating patterns and imposing user/item dependence across domains. A generative model, say ratings over site-time (ROST), which can generate and predict ratings for multiple related CF domains, is developed as the basic model for the framework. We further introduce cross-domain user/item dependence into ROST and extend it to two real-world cross-domain CF scenarios: 1) ROST (sites) for alleviating rating sparsity in the target domain, where multiple similar sites are viewed as related CF domains and some items in the target domain depend on their correspondences in the related ones; and 2) ROST (time) for modeling user-interest drift over time, where a series of time-slices are viewed as related CF domains and a user at current time-slice depends on herself in the previous time-slice. All these ROST models are instances of the proposed unified framework. The experimental results show that ROST (sites) can effectively alleviate the sparsity problem to improve rating prediction performance and ROST (time) can clearly track and visualize user-interest drift over time.

  16. High-order filtering for control volume flow simulation

    NASA Astrophysics Data System (ADS)

    de Stefano, G.; Denaro, F. M.; Riccardi, G.

    2001-12-01

    A general methodology is presented in order to obtain a hierarchy of high-order filter functions, starting from the standard top-hat filter, naturally linked to control volumes flow simulations. The goal is to have a new filtered variable better represented in its high resolved wavenumber components by using a suitable deconvolution. The proposed formulation is applied to the integral momentum equation, that is the evolution equation for the top-hat filtered variable, by performing a spatial reconstruction based on the approximate inversion of the averaging operator. A theoretical analysis for the Burgers' model equation is presented, demonstrating that the local de-averaging is an effective tool to obtain a higher-order accuracy. It is also shown that the subgrid-scale term, to be modeled in the deconvolved balance equation, has a smaller absolute importance in the resolved wavenumber range for increasing deconvolution order. A numerical analysis of the procedure is presented, based on high-order upwind and central fluxes reconstruction, leading to congruent control volume schemes. Finally, the features of the present high-order conservative formulation are tested in the numerical simulation of a sample turbulent flow: the flow behind a backward-facing step. Copyright

  17. Site technology capsule: Filter Flow Technology, Inc. , Colloid polishing filter method

    SciTech Connect

    Ball, T.

    1994-07-01

    The Filter Flow Technology, Inc. (FFT), Colloid Polishing Filter Method (CPFM) was demonstrated at the U.S. Department of Energy's (DOE) Rocky Flats Plant (RFP) as part of the U.S. Environmental Protection Agency's (EPA) Superfund Innovative Technology Evaluation (SITE) program. The CPFM system is designed to remove ionic, colloidal, and complexed radionuclides and heavy metals from water. Pollutants are removed from water predominantly via sorption or chemical complexing. The purpose of the demonstration was to evaluate the ability of the CPFM system to remove low levels of uranium and gross alpha contamination from RFP groundwater.

  18. Delta wings with shock-free cross flow

    NASA Technical Reports Server (NTRS)

    Sritharan, S. S.

    1984-01-01

    In order to have a high level of maneuverability, supersonic delta wings should have a cross flow that is free of embedded shock waves. The conical cross flow sonic surface differs from that of plane transonic flow in many aspects. Well-known properties such as the monotone law are not true for conical cross flow sonic surfaces. By using a local analysis of the cross flow sonic line, relevant conditions for smooth cross flow are obtained. A technique to artificially construct a smooth sonic surface and an efficient numerical method to calculate the flow field are used to obtain cones with smooth cross flow.

  19. Imaging flow cytometer using computation and spatially coded filter

    NASA Astrophysics Data System (ADS)

    Han, Yuanyuan; Lo, Yu-Hwa

    2016-03-01

    Flow cytometry analyzes multiple physical characteristics of a large population of single cells as cells flow in a fluid stream through an excitation light beam. Flow cytometers measure fluorescence and light scattering from which information about the biological and physical properties of individual cells are obtained. Although flow cytometers have massive statistical power due to their single cell resolution and high throughput, they produce no information about cell morphology or spatial resolution offered by microscopy, which is a much wanted feature missing in almost all flow cytometers. In this paper, we invent a method of spatial-temporal transformation to provide flow cytometers with cell imaging capabilities. The method uses mathematical algorithms and a specially designed spatial filter as the only hardware needed to give flow cytometers imaging capabilities. Instead of CCDs or any megapixel cameras found in any imaging systems, we obtain high quality image of fast moving cells in a flow cytometer using photomultiplier tube (PMT) detectors, thus obtaining high throughput in manners fully compatible with existing cytometers. In fact our approach can be applied to retrofit traditional flow cytometers to become imaging flow cytometers at a minimum cost. To prove the concept, we demonstrate cell imaging for cells travelling at a velocity of 0.2 m/s in a microfluidic channel, corresponding to a throughput of approximately 1,000 cells per second.

  20. Ultrasonic Mastering of Filter Flow and Antifouling of Renewable Resources.

    PubMed

    Radziuk, Darya; Möhwald, Helmuth

    2016-04-01

    Inadequate access to pure water and sanitation requires new cost-effective, ergonomic methods with less consumption of energy and chemicals, leaving the environment cleaner and sustainable. Among such methods, ultrasound is a unique means to control the physics and chemistry of complex fluids (wastewater) with excellent performance regarding mass transfer, cleaning, and disinfection. In membrane filtration processes, it overcomes diffusion limits and can accelerate the fluid flow towards the filter preventing antifouling. Here, we outline the current state of knowledge and technological design, with a focus on physicochemical strategies of ultrasound for water cleaning. We highlight important parameters of ultrasound for the delivery of a fluid flow from a technical perspective employing principles of physics and chemistry. By introducing various ultrasonic methods, involving bubbles or cavitation in combination with external fields, we show advancements in flow acceleration and mass transportation to the filter. In most cases we emphasize the main role of streaming and the impact of cavitation with a perspective to prevent and remove fouling deposits during the flow. We also elaborate on the deficiencies of present technologies and on problems to be solved to achieve a wide-spread application. PMID:26601628

  1. Ultrasonic Mastering of Filter Flow and Antifouling of Renewable Resources.

    PubMed

    Radziuk, Darya; Möhwald, Helmuth

    2016-04-01

    Inadequate access to pure water and sanitation requires new cost-effective, ergonomic methods with less consumption of energy and chemicals, leaving the environment cleaner and sustainable. Among such methods, ultrasound is a unique means to control the physics and chemistry of complex fluids (wastewater) with excellent performance regarding mass transfer, cleaning, and disinfection. In membrane filtration processes, it overcomes diffusion limits and can accelerate the fluid flow towards the filter preventing antifouling. Here, we outline the current state of knowledge and technological design, with a focus on physicochemical strategies of ultrasound for water cleaning. We highlight important parameters of ultrasound for the delivery of a fluid flow from a technical perspective employing principles of physics and chemistry. By introducing various ultrasonic methods, involving bubbles or cavitation in combination with external fields, we show advancements in flow acceleration and mass transportation to the filter. In most cases we emphasize the main role of streaming and the impact of cavitation with a perspective to prevent and remove fouling deposits during the flow. We also elaborate on the deficiencies of present technologies and on problems to be solved to achieve a wide-spread application.

  2. Coupled continuum and molecular model of flow through fibrous filter

    NASA Astrophysics Data System (ADS)

    Zhao, Shunliu; Povitsky, Alex

    2013-11-01

    A coupled approach combining the continuum boundary singularity method (BSM) and the molecular direct simulation Monte Carlo (DSMC) is developed and validated using Taylor-Couette flow and the flow about a single fiber confined between two parallel walls. In the proposed approach, the DSMC is applied to an annular region enclosing the fiber and the BSM is employed in the entire flow domain. The parameters used in the DSMC and the coupling procedure, such as the number of simulated particles, the cell size, and the size of the coupling zone are determined by inspecting the accuracy of pressure drop obtained for the range of Knudsen numbers between zero and unity. The developed approach is used to study flowfield of fibrous filtration flows. It is observed that in the partial-slip flow regime, Kn ⩽ 0.25, the results obtained by the proposed coupled BSM-DSMC method match the solution by BSM combined with the heuristic partial-slip boundary conditions. For transition molecular-to-continuum Knudsen numbers, 0.25 < Kn ⩽ 1, the difference in pressure drop and velocity between these two approaches is significant. This difference increases with the Knudsen number that confirms the usefulness of coupled continuum and molecular methods in numerical modeling of transition low Reynolds number flows in fibrous filters.

  3. Numerical modeling and verification of gas flow through a network of crossed narrow v-grooves

    NASA Astrophysics Data System (ADS)

    Bejhed, Johan; Nguyen, Hugo; Åstrand, Peter; Eriksson, Anders; Köhler, Johan

    2006-10-01

    The gas flow through a network of crossing thin micro-machined channels has been successfully modeled and simulated. The crossings are formed by two sets of v-grooves that intersect as two silicon wafers are bonded together. The gas is distributed from inlets via a manifold of channels to the narrow v-grooves. The narrow v-grooves could work as a particle filter. The fluidic model is derived from the Navier-Stokes equation and assumes laminar isothermal flow and incorporates small Knudsen number corrections and Poiseuille number calculations. The simulations use the finite element method. Several elements of the full crossing network model are treated separately before lumping them together: the straight v-grooves, a single crossing in an infinite set and a set of exactly four crossings along the flow path. The introduction of a crossing effectively corresponds to a virtual reduction of the length of the flow path, thereby defining a new effective length. The first and last crossings of each flow path together contribute to a pressure drop equal to that from three ordinary crossings. The derived full network model has been compared to previous experimental results on several differently shaped crossed v-groove networks. Within the experimental errors, the model corresponds to the mass flow and pressure drop measurements. The main error source is the uncertainty in v-groove width which has a profound impact on the fluidic behavior.

  4. Flow Characteristics of Pulse Cleaning System in Ceramic Filter

    SciTech Connect

    Zhongli, J.; Peng, S.; Chen, H.; Shi, M.

    2002-09-19

    The rigid ceramic filters have been recognized to be a most promising kind of equipment for the gas-solid separation and the cleaning of hot gases due to their unique properties and higher separation efficiency for larger than 5 {micro}m particles, which will well meet downstream system component protection and environmental standards. They have potential for increased efficiency in advanced coal-fired power generation systems like pressurized fluidized bed combustion (PFBC) and integrated gasification combined cycle (IGCC) process, and petrochemical process such as fluid catalyst cracking (FCC) Process. In the commercial utilization of rigid ceramic filters, the performance of pulse cleaning systems has crucial effects on the long-term structural durability and reliability of the entire design. In order to get a clear insight into the nature of this cleaning process and provide a solid basis for the industrial applications, the transient flow characteristics of the rigid ceramic candle filter during the whole pulse cleaning process should be completely analyzed.

  5. Tracking low SNR targets using particle filter with flow control

    NASA Astrophysics Data System (ADS)

    Moshtagh, Nima; Romberg, Paul M.; Chan, Moses W.

    2014-06-01

    In this work we study the problem of detecting and tracking challenging targets that exhibit low signal-to-noise ratios (SNR). We have developed a particle filter-based track-before-detect (TBD) algorithm for tracking such dim targets. The approach incorporates the most recent state estimates to control the particle flow accounting for target dynamics. The flow control enables accumulation of signal information over time to compensate for target motion. The performance of this approach is evaluated using a sensitivity analysis based on varying target speed and SNR values. This analysis was conducted using high-fidelity sensor and target modeling in realistic scenarios. Our results show that the proposed TBD algorithm is capable of tracking targets in cluttered images with SNR values much less than one.

  6. Filter-matrix lattice Boltzmann model for incompressible thermal flows.

    PubMed

    Zhuo, Congshan; Zhong, Chengwen; Cao, Jun

    2012-04-01

    In this study, a new filter-matrix lattice Boltzmann (FMLB) model is proposed and extended to include incompressible thermal flows. A new equilibrium solution is found in the improved FMLB model, which is derived from the Hermite expansion. As a result, the velocity-dependent pressure is removed, which is an inherent defect of Somers's FMLB model. In addition, the improved model is extended to include incompressible thermal flows by introducing a class of temperature-distribution function for evaluating the temperature field. Two different temperature-distribution functions are discussed. The improved FMLB model and the temperature-evaluation equation are combined into one coupled model. Numerical simulations are performed on the two-dimensional (2D) lid-driven square cavity flow and the 2D natural convection flow in a square cavity using the improved FMLB model and the two coupled models, respectively. The numerical results of the 2D lid-driven square cavity flow show that the improved FMLB model is superior to the lattice Bhatnagar-Gross-Krook (LBGK) model in terms of both accuracy and stability. When compared with the multi-relaxation-time (MRT) model, the similar accuracy and slightly enhanced stability can be obtained by the improved model. The advantage of the improved model is that it no longer relies on difficult selection of the free parameters requested by the MRT model; in addition, the force term is already included in the collision operator of the improved model. In the case of 2D natural convection flow, the numerical results of the two present models are almost the same, and both exhibit good agreement with the benchmark solution.

  7. Filter-matrix lattice Boltzmann model for incompressible thermal flows

    NASA Astrophysics Data System (ADS)

    Zhuo, Congshan; Zhong, Chengwen; Cao, Jun

    2012-04-01

    In this study, a new filter-matrix lattice Boltzmann (FMLB) model is proposed and extended to include incompressible thermal flows. A new equilibrium solution is found in the improved FMLB model, which is derived from the Hermite expansion. As a result, the velocity-dependent pressure is removed, which is an inherent defect of Somers's FMLB model. In addition, the improved model is extended to include incompressible thermal flows by introducing a class of temperature-distribution function for evaluating the temperature field. Two different temperature-distribution functions are discussed. The improved FMLB model and the temperature-evaluation equation are combined into one coupled model. Numerical simulations are performed on the two-dimensional (2D) lid-driven square cavity flow and the 2D natural convection flow in a square cavity using the improved FMLB model and the two coupled models, respectively. The numerical results of the 2D lid-driven square cavity flow show that the improved FMLB model is superior to the lattice Bhatnagar-Gross-Krook (LBGK) model in terms of both accuracy and stability. When compared with the multi-relaxation-time (MRT) model, the similar accuracy and slightly enhanced stability can be obtained by the improved model. The advantage of the improved model is that it no longer relies on difficult selection of the free parameters requested by the MRT model; in addition, the force term is already included in the collision operator of the improved model. In the case of 2D natural convection flow, the numerical results of the two present models are almost the same, and both exhibit good agreement with the benchmark solution.

  8. Cross-Effects in Microgravity Flows

    NASA Technical Reports Server (NTRS)

    Loyalka, Sudarshan K.; Tompson, R. V.; Ivchenko, I. N.; Ghosh, T. K.; Hamoodi, S. A.; Hickey, K. A.; Huang, C. M.; Tebbe, Patrick A.; Gabis, D. H.; Tekasakul, P.; Bentz, J. A.

    1996-01-01

    Film growth by chemical/physical vapor deposition is a process of considerable interest in microgravity experiments. The absence of natural convection should allow better control of film growth processes but, in highly non-isothermal ampoules, thermal slip (creep) can become a matter of significant concern. The reported research is a theoretical and experimental investigation of the flow of gas/vapor mixtures under non-continuum conditions. The Boltzmann equation has been solved for a monatomic gas under non-condensing conditions and the various phenomenological coefficients have been computed. Computations for realistic potentials as well as for velocity and creep slip have been completed and the creep slip has been found to be dependent on the type of gas confirming the accuracy of previous variational results. The variational technique has been extended and planar flows calculated via the Burnett solutions. Velocity, diffusion and creep slips have been computed for gas mixtures and previously unknown dependencies of the creep slip on the mixture properties have been observed. Also for gas mixtures, an integral representation of the linearized Boltzmann operator has been developed for use in numerical and variational calculations for all intermolecular force laws. Two, two-bulb capillary systems have been designed, built and tested for the measurements of cross-flows; one of glass for isothermal measurements and one of stainless steel for non-isothermal measurements. Extensive data have been collected for Ar-He and N2-He mixtures at a variety of pressures and mole ratios. Viscosity, velocity slip coefficients and tangential momentum accommodation coefficients have been obtained from measurements with a spinning rotor gauge via a new theory that has been formulated for the spinning rotor gauge in the slip regime. The FIDAP fluid dynamics code has been applied to condensing flows in ampoules in the continuum regime and agreement obtained with the earlier work of

  9. Why do Cross-Flow Turbines Stall?

    NASA Astrophysics Data System (ADS)

    Cavagnaro, Robert; Strom, Benjamin; Polagye, Brian

    2015-11-01

    Hydrokinetic turbines are prone to instability and stall near their peak operating points under torque control. Understanding the physics of turbine stall may help to mitigate this undesirable occurrence and improve the robustness of torque controllers. A laboratory-scale two-bladed cross-flow turbine operating at a chord-based Reynolds number ~ 3 ×104 is shown to stall at a critical tip-speed ratio. Experiments are conducting bringing the turbine to this critical speed in a recirculating current flume by increasing resistive torque and allowing the rotor to rapidly decelerate while monitoring inflow velocity, torque, and drag. The turbine stalls probabilistically with a distribution generated from hundreds of such events. A machine learning algorithm identifies stall events and indicates the effectiveness of available measurements or combinations of measurements as predictors. Bubble flow visualization and PIV are utilized to observe fluid conditions during stall events including the formation, separation, and advection of leading-edge vortices involved in the stall process.

  10. Influence of air flow rate and backwashing on the hydraulic behaviour of a submerged filter.

    PubMed

    Cobos-Becerra, Yazmin Lucero; González-Martínez, Simón

    2013-01-01

    The aim of this study was to evaluate backwashing effects on the apparent porosity of the filter media and on the hydraulic behaviour of a pilot scale submerged filter, prior to biofilm colonization, under different hydraulic retention times, and different air flow rates. Tracer curves were analysed with two mathematical models for ideal and non-ideal flow (axial dispersion and Wolf and Resnick models). The filter media was lava stones sieved to 4.5 mm. Backwashing causes attrition of media particles, decreasing the void volume of the filter media and, consequently, the tracer flow is more uniform. The eroded media presented lower dead volumes (79% for the filter with aeration and 8% for the filter without aeration) compared with the new media (83% for the filter with aeration and 22% for the filter without aeration). The flow patterns of eroded and new media were different because the more regular shape of the particles decreases the void volume of the filter media. The dead volume is attributed, in the case of the filter with aeration, to the turbulence caused by the air bubbles that generate preferential channelling of the bulk liquid along the filter media, creating large zones of stagnant liquid and, for the filter without aeration, to the channels formed due to the irregular shaped media.

  11. Highly Inclined Jets in Cross Flow

    NASA Technical Reports Server (NTRS)

    Milanovic, I. M.; Zaman, K. B. M. Q.

    2003-01-01

    Results from an experimental investigation of flow field generated by pitched and yawed jets discharging from a flat plate into a cross-flow are presented. The circular jet was pitched at alpha = 20deg and 45deg and yawed between Beta = 0deg and 90deg in increments of 15deg. The measurements were performed with two ×-wires providing all three components of velocity and turbulent stresses. These data were obtained at downstream locations of x = 3, 5, 10 and 20, where the distance x, normalized by the jet diameter, is measured from the center of the orifice. Data for all configurations were acquired at a momentum-flux ratio J = 8. Additionally, for selected angles and locations, surveys were conducted for J = 1.5, 4, and 20. As expected, the jet penetration is found to be higher at larger alpha. With increasing beta the jet spreads more. The rate of reduction of peak streamwise vorticity, ? max, with the downstream distance is significantly less at higher Beta but is found to be practically independent of alpha. Thus, at the farthest measurement station x = 20, ?xmax is about five times larger for Beta = 75deg compared to the levels at Beta = 0deg. Streamwise velocity within the jet-vortex structure is found to depend on the parameter J. At J = 1.5 and 4, 'wake-like' velocity profiles are observed. In comparison, a 'jet-like' overshoot is present at higher J. Distributions of turbulent stresses for various cases are documented. Peak normal stresses are found to occur within the core of the streamwise vortices. With yaw, at lower values of J, high turbulence is also observed in the boundary layer underneath the jet-vortex structure

  12. Baleen Hydrodynamics and Morphology of Cross-Flow Filtration in Balaenid Whale Suspension Feeding

    PubMed Central

    Werth, Alexander J.; Potvin, Jean

    2016-01-01

    The traditional view of mysticete feeding involves static baleen directly sieving particles from seawater using a simple, dead-end flow-through filtration mechanism. Flow tank experiments on bowhead (Balaena mysticetus) baleen indicate the long-standing model of dead-end filtration, at least in balaenid (bowhead and right) whales, is not merely simplistic but wrong. To recreate continuous intraoral flow, sections of baleen were tested in a flume through which water and buoyant particles circulated with variable flow velocity. Kinematic sequences were analyzed to investigate movement and capture of particles by baleen plates and fringes. Results indicate that very few particles flow directly through the baleen rack; instead much water flows anteroposteriorly along the interior (lingual) side of the rack, allowing items to be carried posteriorly and accumulate at the posterior of the mouth where they might readily be swallowed. Since water flows mainly parallel to rather than directly through the filter, the cross-flow mechanism significantly reduces entrapment and tangling of minute items in baleen fringes, obviating the need to clean the filter. The absence of copepods or other prey found trapped in the baleen of necropsied right and bowhead whales supports this hypothesis. Reduced through-baleen flow was observed with and without boundaries modeling the tongue and lips, indicating that baleen itself is the main if not sole agent of crossflow. Preliminary investigation of baleen from balaenopterid whales that use intermittent filter feeding suggests that although the biomechanics and hydrodynamics of oral flow differ, cross-flow filtration may occur to some degree in all mysticetes. PMID:26918630

  13. A Graphical Filter/Flow Representation of Boolean Queries: A Prototype Implementation and Evaluation.

    ERIC Educational Resources Information Center

    Young, Degi; Shneiderman, Ben

    1993-01-01

    Literature showing the disadvantages of Boolean logic in online searching is reviewed, and research comparing the Filter/Flow visual interface (i.e., a graphical representation of Boolean operators) with a text-only interface is described. A significant difference in the total number of correct queries is reported that favored Filter/Flow. (16…

  14. Final Report: Pilot-scale Cross-flow Filtration Test - Envelope A + Entrained Solids

    SciTech Connect

    Duignan, M.R.

    2000-06-27

    This report discusses the results of the operation of a cross-flow filter in a pilot-scale experimental facility that was designed, built, and run by the Experimental Thermal Fluids Laboratory of the Savannah River Technology Center of the Westinghouse Savannah River Company.This filter technology was evaluated for its inclusion in the pretreatment section of the nuclear waste stabilization plant being designed by BNFL, Inc. This plant will be built at the U.S. Department of Energy's Hanford Site as part of the River Protection Project.

  15. Accumulation and filtering of nanoparticles in microchannels using electrohydrodynamically induced vortical flows.

    PubMed

    Felten, Maika; Staroske, Wolfgang; Jaeger, Magnus S; Schwille, Petra; Duschl, Claus

    2008-07-01

    We present an approach for the accumulation and filtering of nano- and microparticles in microfluidic devices that is based on the generation of electric traveling waves in the radio-frequency range. Upon application of the electric field via a microelectrode array, complex particle trajectories and particle accumulation are observed in well-defined regions in a microchannel. Through the quantitative mapping of the 3-D flow pattern using two-focus fluorescence cross-correlation spectroscopy, two vortices could be identified as one of the sources of the force field that induces the formation of particle clouds. Dielectrophoretic forces that directly act on the particles are the second source of the force field. A thorough 2-D finite element analysis identifies the electric traveling wave mechanism as the cause for the unexpected flow behavior observed. Based on these findings, strategies are discussed, first, for avoiding the vortices to optimize electrohydrodynamic micropumps and, secondly, for utilizing the vortices in the development of microdevices for efficient particle accumulation, separation, and filtering. Such devices may find numerous biomedical applications when highly diluted nano- and microsuspensions have to be processed.

  16. Steerable filters as a tool to determine the orientation of fibers in flowing suspensions

    NASA Astrophysics Data System (ADS)

    Carlsson, Allan; Lundell, Fredrik; Söderberg, L. Daniel

    2008-11-01

    Fiber suspension flows are found in industrial applications such as paper manufacturing and polymer processing. In order to experimentally study fiber motions in such suspensions it is essential to be able to determine the position and orientation of fibers as a function of time. One method to extract this information from captured images is to use image filtering. The image filtering is based on computing convolutions of the images with a filter matrix that resembles a fiber. Steerable filters represent a class of filters where an arbitrary orientation of the filter can be obtained from a linear combination of a limited set of basis filters. Since the basis filters are not orientation dependent this makes it possible to eliminate the orientation dependency from the convolutions. Here a specific steerable filter is evaluated for functionality of finding the position and orientation of fibers in a flowing suspension. Through application of the filter on artificially generated test images with known fiber orientation it is possible to show that the error is less than 1 degree. A good agreement is also found when comparing the orientation distribution with a robust, but computationally more expensive, method on a real flow case where fibers are suspended in a shear flow.

  17. The Effect of Cross Flow on Slat Noise

    NASA Technical Reports Server (NTRS)

    Lockard, David P.; Choudhari, Meelan M.

    2010-01-01

    This paper continues the computational examination (AIAA Journal, Vol. 45, No. 9, 2007, pp. 2174-2186) of the unsteady flow within the slat cove region of a multi-element high-lift airfoil configuration. Two simulations have been performed to examine the effect of cross flow on the near-field fluctuations and far-field acoustics. The cross flow was imposed by changing the free-stream velocity vector and modifying the Reynolds number. The cross flow does appear to alter the dynamics in the cove region, but the impact on the noise seems to be more dependent on the flow conditions. However, separating out the true effects of the cross flow from those of the Mach and Reynolds number would require additional calculations to isolate those effects.

  18. Cross flow characteristics in a three fuel assemblies

    SciTech Connect

    Bae, J. H.; Euh, D. J.; Park, C. K.; Youn, Y. J.; Kwon, T. S.

    2012-07-01

    To evaluate the reactor thermal margin of APR+, reactor core flow distribution including both axial and lateral directional hydraulic resistances of fuel assemblies should be known. 3-Ch cross flow test facility has been constructed with three full-size fuel assemblies to investigate the cross flow characteristics. Performance tests have been performed. The axial and lateral directional hydraulic resistances of fuel assemblies have been measured. The test results have been compared to the CFD calculation. (authors)

  19. Flow in tubes of non-circular cross-sections

    NASA Astrophysics Data System (ADS)

    Quadir, Raushan Ara

    Laminar, viscous, incompressible flow in tubes of noncircular cross sections is investigated. The specific aims of the investigation are (1) to look at the problems of both developing flow and fully developed flow, (2) to consider noncircular cross sections in a more systematic manner than has been done in the past, and (3) to develop a relatively simple finite element technique for producing accurate numerical solutions of flow in tubes of fairly arbitrary cross sections. Fully developed flow in tubes is governed by a Poisson type equation for the mainstream velocity. Both analytical and numerical solutions are considered. The cross sections studied include elliptic and rectangular cross sections of different aspect ratios, some triangular cross sections, and a series of crescent-shaped cross sections. The physical characteristics of the flow are examined in a systematic manner in order to determine how these characteristics are affected by certain geometrical features of the cross section. Solutions fall into three basic categories depending on the shape of the cross section. In the first category, which includes circular and elliptic cross sections, solutions are possible in closed form. In the second, including rectangular and some triangular cross sections, solutions are in the form of infinite series. In the third, including cross sections of more complicated or irregular shapes, only numerical solutions are possible. Results of calculations of velocity profiles, flow rate, pumping power, and friction factor are presented in a way which can be useful for engineering applications. In numerical studies of both developing and fully developed flow finite element techniques are used. Results are obtained for tubes of rectangular and elliptic cross sections of different aspect ratios, for tubes of crescent-shaped cross sections, and a tube whose cross section is an oval of Cassini. For fully developed flow, results are compared with the corresponding exact

  20. Flow in Tubes of Non-Circular Cross-Sections

    NASA Astrophysics Data System (ADS)

    Quadir, Raushan Ara

    In this thesis steady, laminar, viscous, incompressible flow in tubes of non-circular cross sections is investigated. The specific aims of the investigation are (a) to look at the problems of both developing flow and fully developed flow, (b) to consider non-circular cross sections in a more systematic manner than has been done in the past, and (c) to develop a relatively simple finite element technique for producing accurate numerical solutions of flow in tubes of fairly arbitrary cross sections. Fully developed flow in tubes is governed by a Poisson type equation for the mainstream velocity. Both analytical and numerical solutions are considered. The cross sections studied include elliptic and rectangular cross sections of different aspect ratios, some triangular cross sections, and a series of crescent-shaped cross sections. The physical characteristics of the flow are examined in a systematic manner in order to determine how these characteristics are affected by certain geometrical features of the cross section. Solutions fall into three basic categories depending on the shape of the cross section. In the first category, which includes circular and elliptic cross sections, solutions are possible in closed form. In the second, including rectangular and some triangular cross sections, solutions are in the form of infinite series. In the third, including cross sections of more complicated or irregular shapes, only numerical solutions are possible. Results of calculations of velocity profiles, flow rate, pumping power, and friction factor are presented in a way which can be useful for engineering applications. In numerical studies of both developing and fully developed flow finite element techniques are used. Results are obtained for tubes of rectangular and elliptic cross sections of different aspect ratios, for tubes of crescent -shaped cross sections and a tube whose cross section is an oval of Cassini. For fully developed flow, results are compared with the

  1. Computational Modeling of Blood Flow in the TrapEase Inferior Vena Cava Filter

    SciTech Connect

    Singer, M A; Henshaw, W D; Wang, S L

    2008-02-04

    To evaluate the flow hemodynamics of the TrapEase vena cava filter using three dimensional computational fluid dynamics, including simulated thrombi of multiple shapes, sizes, and trapping positions. The study was performed to identify potential areas of recirculation and stagnation and areas in which trapped thrombi may influence intrafilter thrombosis. Computer models of the TrapEase filter, thrombi (volumes ranging from 0.25mL to 2mL, 3 different shapes), and a 23mm diameter cava were constructed. The hemodynamics of steady-state flow at Reynolds number 600 was examined for the unoccluded and partially occluded filter. Axial velocity contours and wall shear stresses were computed. Flow in the unoccluded TrapEase filter experienced minimal disruption, except near the superior and inferior tips where low velocity flow was observed. For spherical thrombi in the superior trapping position, stagnant and recirculating flow was observed downstream of the thrombus; the volume of stagnant flow and the peak wall shear stress increased monotonically with thrombus volume. For inferiorly trapped spherical thrombi, marked disruption to the flow was observed along the cava wall ipsilateral to the thrombus and in the interior of the filter. Spherically shaped thrombus produced a lower peak wall shear stress than conically shaped thrombus and a larger peak stress than ellipsoidal thrombus. We have designed and constructed a computer model of the flow hemodynamics of the TrapEase IVC filter with varying shapes, sizes, and positions of thrombi. The computer model offers several advantages over in vitro techniques including: improved resolution, ease of evaluating different thrombus sizes and shapes, and easy adaptation for new filter designs and flow parameters. Results from the model also support a previously reported finding from photochromic experiments that suggest the inferior trapping position of the TrapEase IVC filter leads to an intra-filter region of recirculating

  2. Divergence Free High Order Filter Methods for Multiscale Non-ideal MHD Flows

    NASA Technical Reports Server (NTRS)

    Yee, H. C.; Sjoegreen, Bjoern

    2003-01-01

    Low-dissipative high order filter finite difference methods for long time wave propagation of shock/turbulence/combustion compressible viscous MHD flows has been constructed. Several variants of the filter approach that cater to different flow types are proposed. These filters provide a natural and efficient way for the minimization of the divergence of the magnetic field (Delta . B) numerical error in the sense that no standard divergence cleaning is required. For certain 2-D MHD test problems, divergence free preservation of the magnetic fields of these filter schemes has been achieved.

  3. Design of cross-coupled planar microstrip band-pass filters using a novel adjustment method

    NASA Astrophysics Data System (ADS)

    Alkafaji, Muhammed S. S.

    2015-02-01

    In this paper the design of a cross-coupled planar microwave band-pass filter using open-loop square microstrip resonators, with two symmetrically placed attenuation poles, is presented. The design starts from the following specifications: central frequency 3GHz, 150MHz bandwidth, 1dB ripple in the pass-band corresponding to return loss of 6.8dB.The adjustment method using additional ports placed on each resonator of the filter is used, allowing the interconnection of the filter structure with external lumped elements. Connecting a reactive element (capacitor) from such an additional port to ground allows a fine tuning of the resonator. Connecting a reactive element between two such additional ports allows a fine change in the coupling coefficient between these resonators. After adding four extra ports and connecting the external elements (capacitors), it is possible to use fast circuit simulation software to optimize the filter's response. Then all these capacitors have to be gradually eliminated, by compensating their effects through fine changes back in the layouts. If some specific issues are properly handled, this procedure improves considerably the quality of the final design of the filter. After a thorough optimization of the layout, the filter was fabricated and measured. The results of measurements are in good agreement with the specifications of the filter, showing this way the efficiency of the applied optimization method.

  4. Dynamic User Interface for Cross-plot, Filtering and Upload/Download of Time Series Data

    NASA Astrophysics Data System (ADS)

    Olsen, K.; Zhu, J.; Talley, J.

    2006-12-01

    We have generated a user-friendly web-interface that allows for dynamic filtering and cross-plot of time series data. The interface is an extension of our existing php software associated with the Storage Resource Broker (SRB) at the San Diego Supercomputer Center (SDSC). The extension includes the possibility of dynamic low- pass filtering and cross-plotting several time histories associated with a specific site. Moreover, regular-spaced scalar data can be cross-contoured with choice of contour interval, labeling, etc. Also associated with the interface is software to upload and download sets of synthetic time histories and scalar contour data on a regular grid using a web browser. The software is well suited for numerical code validation exercises, generating output such as sliprate histories, rupture time distributions, ground motion histories, and peak ground motions, as well as comparison of ensembles of ground motion scenarios.

  5. Cross-flow versus counterflow air-stripping towers

    SciTech Connect

    Little, J.C.; Marinas, B.J.

    1997-07-01

    Mass-transfer and pressure-drop packing performance correlations are used together with tower design equations and detailed cost models to compare the effectiveness of cross-flow and counterflow air stripping towers over a wide range of contaminant volatility. Cross-flow towers are shown to offer a significant economic advantage over counterflow towers when stripping low volatility organic contaminants primarily due to savings in energy costs. These savings increase as contaminant volatility decreases and as water flow rate increases. A further advantage of the cross-flow configuration is that it extends the feasible operating range for air stripping as cross-flow towers can accommodate higher air-to-water flow ratios than conventional counterflow towers. Finally it is shown that the optimized least-cost design for both counterflow and cross-flow towers varies with Henry`s law constant, water flow rate, and percent removal, but that the optimum is virtually insensitive to other cost and operating variables. This greatly simplifies the tower design procedure.

  6. Calculation and Verification of the Behaviour of Vertical Fluid Flow Using the Multifunctional Fluid Filter

    NASA Astrophysics Data System (ADS)

    Fujiwara, Kuniyo; Ukita, Yoshiaki; Asano, Toshifumi; Matsui, Katsuhiro; Takeo, Masahiro; Negoro, Seiji; Utsumi, Yuuichi

    The vertical fluid flow operation and multifunctional fluid filter for the operation were proposed. We calculated the flow behaviour by FLUENT of the CFD software. The CFD analysis estimated the threshold pressure of flow transmission and efficiency of mixing and the results indicated that the vertical liquid transportation is useful and the good multi function as channel , valve , mixer and micro reactor of the filter we proposed. So we fabricated the filter by SR lithography and performed the flow transmission experiment. As the result, the calculated threshold pressure configurate the measured pressure. We demonstrated ring-opening reaction of the Catechol by Catechol 2,3-dioxygenase as the catalyst to evaluate the performance of mixing. It shows that the filter mixes the fluid efficiently and is enough to mix at five times transportation.

  7. Filtering effect of wind flow turbulence on atmospheric pollutant dispersion.

    PubMed

    Yassin, Mohamed F

    2012-06-01

    This paper presents a model for coupling the statistics of wind velocity distribution and atmospheric pollutant dispersion. The effect of wind velocity distribution is modeled as a three-dimensional finite-impulse response (3D-FIR) filter. A phase space representation of the 3D-FIR filter window is discussed. The resulting pollutant dispersion is the multiplication in the phase space of the 3-D Fourier transform of the pollutant concentration and the volume described by the filter window coefficients. The shape of the filter window in the phase space enables representing such effects as vortex shedding thermal currents, etc. The impact of spatial distribution of the sensors on the resulting pollutant spatial distribution and the 3-D FIR filter model employed also discuss. The case of a neutrally buoyant plume emitted from an elevated point source in a turbulent boundary layer considers. The results show that wind turbulence is an important factor in the pollutant dispersion and introduces expected random fluctuations in pollutant distribution and leads to spreading the distribution due to wind mixing.

  8. Study on an undershot cross-flow water turbine

    NASA Astrophysics Data System (ADS)

    Nishi, Yasuyuki; Inagaki, Terumi; Li, Yanrong; Omiya, Ryota; Fukutomi, Junichiro

    2014-06-01

    This study aims to develop a water turbine suitable for ultra-low heads in open channels, with the end goal being the effective utilization of unutilized hydroelectric energy in agricultural water channels. We performed tests by applying a cross-flow runner to an open channel as an undershot water turbine while attempting to simplify the structure and eliminate the casing. We experimentally investigated the flow fields and performance of water turbines in states where the flow rate was constant for the undershot cross-flow water turbine mentioned above. In addition, we compared existing undershot water turbines with our undershot cross-flow water turbine after attaching a bottom plate to the runner. From the results, we were able to clarify the following. Although the effective head for cross-flow runners with no bottom plate was lower than those found in existing runners equipped with a bottom plate, the power output is greater in the high rotational speed range because of the high turbine efficiency. Also, the runner with no bottom plate differed from runners that had a bottom plate in that no water was being wound up by the blades or retained between the blades, and the former received twice the flow due to the flow-through effect. As a result, the turbine efficiency was greater for runners with no bottom plate in the full rotational speed range compared with that found in runners that had a bottom plate.

  9. [Design Method Analysis and Performance Comparison of Wall Filter for Ultrasound Color Flow Imaging].

    PubMed

    Wang, Lutao; Xiao, Jun; Chai, Hua

    2015-08-01

    The successful suppression of clutter arising from stationary or slowly moving tissue is one of the key issues in medical ultrasound color blood imaging. Remaining clutter may cause bias in the mean blood frequency estimation and results in a potentially misleading description of blood-flow. In this paper, based on the principle of general wall-filter, the design process of three classes of filters, infinitely impulse response with projection initialization (Prj-IIR), polynomials regression (Pol-Reg), and eigen-based filters are previewed and analyzed. The performance of the filters was assessed by calculating the bias and variance of a mean blood velocity using a standard autocorrelation estimator. Simulation results show that the performance of Pol-Reg filter is similar to Prj-IIR filters. Both of them can offer accurate estimation of mean blood flow speed under steady clutter conditions, and the clutter rejection ability can be enhanced by increasing the ensemble size of Doppler vector. Eigen-based filters can effectively remove the non-stationary clutter component, and further improve the estimation accuracy for low speed blood flow signals. There is also no significant increase in computation complexity for eigen-based filters when the ensemble size is less than 10.

  10. Performance Evaluation of Axial Flow AG-1 FC and Prototype FM (High Strength) HEPA Filters - 13123

    SciTech Connect

    Giffin, Paxton K.; Parsons, Michael S.; Wilson, John A.; Waggoner, Charles A.

    2013-07-01

    High efficiency particulate air (HEPA) filters are routinely used in DOE nuclear containment activities. The Nuclear Air Cleaning Handbook (NACH) stipulates that air cleaning devices and equipment used in DOE nuclear applications must meet the American Society of Mechanical Engineers (ASME) Code on Nuclear Air and Gas Treatment (AG-1) standard. This testing activity evaluates two different axial flow HEPA filters, those from AG-1 Sections FC and FM. Section FM is under development and has not yet been added to AG-1 due to a lack of qualification data available for these filters. Section FC filters are axial flow units that utilize a fibrous glass filtering medium. The section FM filters utilize a similar fibrous glass medium, but also have scrim backing. The scrim-backed filters have demonstrated the ability to endure pressure impulses capable of completely destroying FC filters. The testing activities presented herein will examine the total lifetime loading for both FC and FM filters under ambient conditions and at elevated conditions of temperature and relative humidity. Results will include loading curves, penetration curves, and testing condition parameters. These testing activities have been developed through collaborations with representatives from the National Nuclear Security Administration (NNSA), DOE Office of Environmental Management (DOE-EM), New Mexico State University, and Mississippi State University. (authors)

  11. Micro-jets in confined turbulent cross flow

    SciTech Connect

    Kelman, J.B.; Greenhalgh, D.A.; Whiteman, M.

    2006-03-01

    The mixing of sub-millimetre diameter jets issuing into a turbulent cross flow is examined with a combination of laser diagnostic techniques. The cross flow stream is in a confined duct and the micro-jet issue from the sides of injector vanes. A range of cross jet momentum ratios, cross flow temperatures and turbulence intensities are investigated to examine the influence on the jet mixing. Methane, seeded with acetone, was used to measure the concentrations of the jets and the mixing of the jet fluid in the duct. Unlike previous jet in cross flow work, mixing appears to be dominated by the free stream turbulence, rather than the cross jet momentum ratios. Temperature increases in the free stream appear to increase the rate of mixing in the duct, despite the associated decrease in the Reynolds number. The dominance of the free stream turbulence in controlling the mixing is of particular interest in respect of gas turbine injection systems, as the cross jet momentum ratio is insufficient in defining the mixing process. (author)

  12. Comparison of NOM removal and microbial properties in up-flow/down-flow BAC filter.

    PubMed

    Han, Lineng; Liu, Wenjun; Chen, Mo; Zhang, Minglu; Liu, Shuming; Sun, Ruilin; Fei, Xiangqin

    2013-09-15

    The removal of natural organic matter (NOM) in term of CODMn by up-flow biologically activated carbon filter (UBACF) and down-flow biologically activated carbon filter (DBACF) was investigated in a pilot-scale test. The impacts of the molecular weight distribution of NOM on its degradation by the UBACF and DBACF were evaluated. The relationship between biodegradation and the microbial properties in the UBACF and DBACF were approached as well. The feed water of the UBACF and DBACF were pumped from the effluent of the rapid sand filtration (RSF) of Chengnan Drinking Water Treatment Plant (CDWTP), Huaian, Jiangsu Province, China. When the adsorption was the dominant mechanism of NOM removal at the initial stage of operation, the CODMn removal efficiency by the UBACF was lower than the DBACF. However, with the microbes gradually accumulated and biofilm formed, the removal of CODMn by the UBACF increased correspondingly to 25.3%, at the steady-state operation and was approximately 10% higher than that by the DBACF. Heterotrophy plate count (HPC) in the finished water of the UBACF was observed 30% higher than that of the DBACF. The UBACF effluent had higher concentration of detached bacteria whereas the DBACF harbored more attached biomass. The highest attached biomass concentration of the UBACF was found in the middle of the GAC bed. On the contrary, the highest attached biomass concentration of the DBACF was found on the top of the GAC bed. Furthermore, a total of 9479 reads by pyrosequencing was obtained from samples of the UBACF and DBACF effluents. The UBACF effluent had a more diverse microbial community and more even distribution of species than the DBACF effluent did. Alphaproteobacteria and Betaproteobacteria were the dominant groups in the finished water of the UBACF and DBACF. The higher organic matter removal by the UBACF was attributed to the presence of its higher biologically activity.

  13. N95 and p100 respirator filter efficiency under high constant and cyclic flow.

    PubMed

    Eshbaugh, Jonathan P; Gardner, Paul D; Richardson, Aaron W; Hofacre, Kent C

    2009-01-01

    This study investigated the effect of high flow conditions on aerosol penetration and the relationship between penetration at constant and cyclic flow conditions. National Institute for Occupational Safety and Health (NIOSH)-approved N95 and P100 filtering facepiece respirators and cartridges were challenged with inert solid and oil aerosols. A combination of monodisperse aerosol and size-specific aerosol measurement equipment allowed count-based penetration measurement of particles with nominal diameters ranging from 0.02 to 2.9 microm. Three constant flow conditions (85, 270, and 360 L/min) were selected to match the minute, inhalation mean, and inhalation peak flows of the four cyclic flow conditions (40, 85, 115, and 135 L/min) tested. As expected, penetration was found to increase under increased constant and cyclic flow conditions. The most penetrating particle size (MPPS) generally ranged from 0.05 to 0.2 microm for P100 filters and was approximately 0.05 microm for N95 filters. Although penetration increased at the high flow conditions, the MPPS was relatively unaffected by flow. Of the constant flows tested, the flows equivalent to cyclic inhalation mean and peak flows best approximated the penetration measurements of the corresponding cyclic flows. PMID:19012163

  14. Turbulent combustion flow through variable cross section channel

    SciTech Connect

    Rogov, B.V.; Sokolova, I.A.

    1999-07-01

    The object of this study is to develop a new evolutionary numerical method for solving direct task of Laval nozzle, which provides non-iterative calculations of chemical reacting turbulent flows with detailed kinetic chemistry. The numerical scheme of fourth order along the normal coordinate and second order along the streamwise one is derived for calculation of difference-differential equations of the second order and the first order. Marching method provides the possibility of computing field flow in subsonic section of nozzle and near an expansion. Critical mass consumption is calculated with controlled accuracy. After critical cross section of nozzle a combined marching method with global iterations over axial pressure (only) makes it possible to overcome ill posedness of mixed supersonic flow and calculate the whole flow field near and after critical cross section. Numerical results are demonstrated on turbulent burning hydrogen-oxygen flow through Laval nozzle with curvature of wall K{sub w} = 0.5.

  15. Mixing Effects on the Precipitation and Cross Flows Filtration of a Hanford Simulated Precipitated Radioactive Waste

    SciTech Connect

    DUIGNAN, MARK

    2004-03-31

    As part of the River Protection Project at Hanford, Washington, Bechtel National, Inc. has been contracted by the United States Department of Energy to design a Waste Treatment and Immobilization Plant to stabilize liquid radioactive waste. Because of its experience with radioactive waste stabilization, the Savannah River Technology Center of the Westinghouse Savannah River Company is working with Bechtel National and Washington Group International, to help design and test certain parts of the Waste Treatment Plant. One part of the process is the separation of radioactive isotopes from the liquid waste by a precipitation reaction and cross-flow ultrafiltration. To better understand those combined processes an experiment was performed using a simulated radioactive waste, made to prototypically represent the chemical and physical characteristics of a Hanford waste in tank 241-AN-102 and precipitated under prototypic conditions. The resultant slurry was then filtered using a cross-flow filter prototypic in porosity, length, and diameter to the plant design. An important aspect of filtration for waste treatment is the rate at which permeate is produced. There are many factors that affect filtration rate and one of the most difficult to obtain is the effect of particles in the waste streams. The Waste Treatment Plant will filter many waste streams, with varying concentrations and types of dissolved and undissolved solids. An added complication is the need to precipitate organic complexants so they can be efficiently separated from the supernatant. Depending on how precipitation is performed, the newly created solids will add to the complicating factors that determine permeate flux rate. To investigate the effect of precipitated solids on filter flux a pilot-scale test was performed and two different mixing mechanisms were used for the precipitation reaction. A standard impeller type mixer, which created a homogeneous mixture, and a pulse jet mixer, which created a

  16. Image Cross-Correlation Analysis of Time Varying Flows.

    PubMed

    Marquezin, Cassia A; Ceffa, Nicolò G; Cotelli, Franco; Collini, Maddalena; Sironi, Laura; Chirico, Giuseppe

    2016-07-19

    In vivo studies of blood circulation pathologies have great medical relevance and need methods for the characterization of time varying flows at high spatial and time resolution in small animal models. We test here the efficacy of the combination of image correlation techniques and single plane illumination microscopy (SPIM) in characterizing time varying flows in vitro and in vivo. As indicated by numerical simulations and by in vitro experiments on straight capillaries, the complex analytical form of the cross-correlation function for SPIM detection can be simplified, in conditions of interest for hemodynamics, to a superposition of Gaussian components, easily amenable to the analysis of variable flows. The possibility to select a wide field of view with a good spatial resolution along the collection optical axis and to compute the cross-correlation between regions of interest at varying distances on a single time stack of images allows one to single out periodic flow components from spurious peaks on the cross-correlation functions and to infer the duration of each flow component. We apply this cross-correlation analysis to the blood flow in Zebrafish embryos at 4 days after fertilization, measuring the average speed and the duration of the systolic and diastolic phases.

  17. Modeling Flow Past a TrapEase Inferior Vena Cava Filter

    NASA Astrophysics Data System (ADS)

    Singer, Michael; Henshaw, William; Wang, Stephen

    2008-11-01

    This study uses three-dimensional computational fluid dynamics to evaluate the efficacy of the TrapEase inferior vena cava (IVC) filter. Hemodynamics of the unoccluded and partially occluded filter are examined, and the clinical implications are assessed. The IVC, which is the primary vein that drains the legs, is modeled as a straight pipe, and a geometrically accurate model of the filter is constructed using computer aided design. Blood is modeled as a homogeneous, incompressible, Newtonian fluid, and the method of overset grids is used to solve the Navier-Stokes equations. Results are corroborated with in-vitro studies. Flow around the unoccluded filter demonstrates minimal disruption, but spherical clots in the downstream trapping position lead to regions of stagnant and recirculating flow that may promote further clotting. The volume of stagnant flow and the peak wall shear stress increase with clot volume. For clots trapped in the upstream trapping position, flow is disrupted along the cava wall downstream of the clot and within the filter. The shape and location of trapped clots also effect the peak wall shear stress and may impact the efficacy of the filter.

  18. Formation of scalloped cross-bedding without unsteady flows.

    USGS Publications Warehouse

    Rubin, D.M.

    1987-01-01

    Scalloped cross-bedding formed by fluctuating flow superficially resembles that formed by superimposed or intersecting bedforms, but, as illustrated in three-dimensional computer plots, the two kinds of structures commonly can be distinguished by directional properties of the bedding. Scallops deposited by alongslope-migrating, superimposed bedforms have cross-bed and bounding-surface dip patterns that lack bilateral symmetry and have cross-bed dips that are asymmetrically distributed relative to bounding-surface dips. Scallops with dip patterns that are bilaterally symmetrically distributed relative to the bounding-surface dips can be produced either by fluctuating flow or by downslope or upslope migration of superimposed bedforms. An example of nearshore-marine scalloped cross-bedding of Pleistocene age was examined in detail in a coastal terrace of Monterey Bay, California. -from Author

  19. Construction of Low Dissipative High Order Well-Balanced Filter Schemes for Non-Equilibrium Flows

    NASA Technical Reports Server (NTRS)

    Wang, Wei; Yee, H. C.; Sjogreen, Bjorn; Magin, Thierry; Shu, Chi-Wang

    2009-01-01

    The goal of this paper is to generalize the well-balanced approach for non-equilibrium flow studied by Wang et al. [26] to a class of low dissipative high order shock-capturing filter schemes and to explore more advantages of well-balanced schemes in reacting flows. The class of filter schemes developed by Yee et al. [30], Sjoegreen & Yee [24] and Yee & Sjoegreen [35] consist of two steps, a full time step of spatially high order non-dissipative base scheme and an adaptive nonlinear filter containing shock-capturing dissipation. A good property of the filter scheme is that the base scheme and the filter are stand alone modules in designing. Therefore, the idea of designing a well-balanced filter scheme is straightforward, i.e., choosing a well-balanced base scheme with a well-balanced filter (both with high order). A typical class of these schemes shown in this paper is the high order central difference schemes/predictor-corrector (PC) schemes with a high order well-balanced WENO filter. The new filter scheme with the well-balanced property will gather the features of both filter methods and well-balanced properties: it can preserve certain steady state solutions exactly; it is able to capture small perturbations, e.g., turbulence fluctuations; it adaptively controls numerical dissipation. Thus it shows high accuracy, efficiency and stability in shock/turbulence interactions. Numerical examples containing 1D and 2D smooth problems, 1D stationary contact discontinuity problem and 1D turbulence/shock interactions are included to verify the improved accuracy, in addition to the well-balanced behavior.

  20. Wavelength interrogation of fiber Bragg grating sensors based on crossed optical Gaussian filters.

    PubMed

    Cheng, Rui; Xia, Li; Zhou, Jiaao; Liu, Deming

    2015-04-15

    Conventional intensity-modulated measurements require to be operated in linear range of filter or interferometric response to ensure a linear detection. Here, we present a wavelength interrogation system for fiber Bragg grating sensors where the linear transition is achieved with crossed Gaussian transmissions. This unique filtering characteristic makes the responses of the two branch detections follow Gaussian functions with the same parameters except for a delay. The substraction of these two delayed Gaussian responses (in dB) ultimately leads to a linear behavior, which is exploited for the sensor wavelength determination. Beside its flexibility and inherently power insensitivity, the proposal also shows a potential of a much wider operational range. Interrogation of a strain-tuned grating was accomplished, with a wide sensitivity tuning range from 2.56 to 8.7 dB/nm achieved.

  1. Measuring two phase flow parameters using impedance cross-correlation flow meter

    NASA Astrophysics Data System (ADS)

    Muhamedsalih, Y.; Lucas, G.

    2012-03-01

    This paper describes the design and implementation of an impedance cross correlation flow meter which can be used in solids-water pipe flows to measure the local solids volume fraction distribution and the local solids velocity distribution. The system is composed of two arrays of electrodes, separated by an axial distance of 50 mm and each array contains eights electrodes mounted over the internal circumference of the pipe carrying the flow. Furthermore every electrode in each array can be selected to be either"excitation", "measurement" or "earth". Changing the electrode configuration leads to a change in the electric field, and hence in the region of the flow cross section which is interrogated. The local flow velocity in the interrogated region is obtained by cross correlation between the two electrode arrays. Additionally, the local solids volume fraction can be obtained from the mean mixture conductivity in the region under interrogation. The system is being integrated with a microcontroller to measure the velocity distribution of the solids and the volume fraction distribution of the solids in order to create a portable flow meter capable of measuring the multi-phase flow parameters without the need of a PC to control it. Integration of the product of the local solids volume fraction and the local solids velocity in the flow cross section enables the solids volumetric flow rate to be determined.

  2. An optical absorption cell with vapor cross flow.

    NASA Technical Reports Server (NTRS)

    Hendrickson, P. E.; Walls, W. L.; Broersma, S.

    1973-01-01

    Description of a water vapor cross flow system that simulates meteorological conditions and effectively curbs any disturbing effects of walls and vacuum connections in an optical absorption cell. Vapor equilibrium is established within 30 min. A 6.3 micron infrared beam traverses the pressure, temperature, and humidity controlled vapor column. The effect of these thermodynamic parameters can be examined.

  3. Evaluation of N95 filtering facepiece respirator efficiency with cyclic and constant flows.

    PubMed

    Bahloul, Ali; Mahdavi, Alireza; Haghighat, Fariborz; Ostiguy, Claude

    2014-01-01

    An increasing demand for protecting workers against harmful inhalable ultrafine particles (UFPs), by means of filtering facepiece respirators (FFRs), necessitates assessing the efficiency of FFRs. This article evaluates the penetration of particles, mostly in the ultrafine range, through one model of N95 FFRs exposed to cyclic and constant flows, simulating breathing for moderate to heavy work loads. The generated particles were poly-dispersed NaCl, within the range of 10-205.4 nm. The tests were performed for several cyclic flows, with mean inhalation flows (MIFs) ranging from 42 to 360 L/min, and constant flows with the same range. The measurements were based on filter penetration and did not consider particle leakage. With the penetrations recorded for the selected constant and cyclic flows, the worst-case scenario penetrations at the most penetrating particle size (MPPS) were obtained. The MPPS penetrations measured with the cyclic and constant flows equivalent to minute volume, MIF and peak inhalation flow (PIF) of the cyclic flows were then compared. It was indicated that the constant flows equivalent to the minute volume or PIF of the cyclic flow could not accurately represent the penetration of the corresponding cyclic flow: the constant flow equal to the minute volume of the cyclic flow significantly underestimated the MPPS penetration of the corresponding cyclic flow, while the constant flow equal to the PIF of the cyclic flow overestimated it. On the other hand, for the constant flow equal to the MIF of the cyclic flow, the MPPS penetrations were almost equal for both the constant and cyclic flows, for the lower flow rates (42 to 170 L/min). For higher flow rates (230 to 360 L/min), however, the MPPS penetration was exceeded under the constant flows, compared with the corresponding cyclic flows. It was therefore concluded that the constant flow equal to the MIF of the cyclic flow could better predict the results of corresponding cyclic flow, since it

  4. File-Based Data Flow in the CMS Filter Farm

    SciTech Connect

    Andre, J.M.; et al.

    2015-12-23

    During the LHC Long Shutdown 1, the CMS Data Acquisition system underwent a partial redesign to replace obsolete network equipment, use more homogeneous switching technologies, and prepare the ground for future upgrades of the detector front-ends. The software and hardware infrastructure to provide input, execute the High Level Trigger (HLT) algorithms and deal with output data transport and storage has also been redesigned to be completely file- based. This approach provides additional decoupling between the HLT algorithms and the input and output data flow. All the metadata needed for bookkeeping of the data flow and the HLT process lifetimes are also generated in the form of small “documents” using the JSON encoding, by either services in the flow of the HLT execution (for rates etc.) or watchdog processes. These “files” can remain memory-resident or be written to disk if they are to be used in another part of the system (e.g. for aggregation of output data). We discuss how this redesign improves the robustness and flexibility of the CMS DAQ and the performance of the system currently being commissioned for the LHC Run 2.

  5. File-based data flow in the CMS Filter Farm

    NASA Astrophysics Data System (ADS)

    Andre, J.-M.; Andronidis, A.; Bawej, T.; Behrens, U.; Branson, J.; Chaze, O.; Cittolin, S.; Darlea, G.-L.; Deldicque, C.; Dobson, M.; Dupont, A.; Erhan, S.; Gigi, D.; Glege, F.; Gomez-Ceballos, G.; Hegeman, J.; Holzner, A.; Jimenez-Estupiñán, R.; Masetti, L.; Meijers, F.; Meschi, E.; Mommsen, R. K.; Morovic, S.; Nunez-Barranco-Fernandez, C.; O'Dell, V.; Orsini, L.; Paus, C.; Petrucci, A.; Pieri, M.; Racz, A.; Roberts, P.; Sakulin, H.; Schwick, C.; Stieger, B.; Sumorok, K.; Veverka, J.; Zaza, S.; Zejdl, P.

    2015-12-01

    During the LHC Long Shutdown 1, the CMS Data Acquisition system underwent a partial redesign to replace obsolete network equipment, use more homogeneous switching technologies, and prepare the ground for future upgrades of the detector front-ends. The software and hardware infrastructure to provide input, execute the High Level Trigger (HLT) algorithms and deal with output data transport and storage has also been redesigned to be completely file- based. This approach provides additional decoupling between the HLT algorithms and the input and output data flow. All the metadata needed for bookkeeping of the data flow and the HLT process lifetimes are also generated in the form of small “documents” using the JSON encoding, by either services in the flow of the HLT execution (for rates etc.) or watchdog processes. These “files” can remain memory-resident or be written to disk if they are to be used in another part of the system (e.g. for aggregation of output data). We discuss how this redesign improves the robustness and flexibility of the CMS DAQ and the performance of the system currently being commissioned for the LHC Run 2.

  6. A novel pitch evaluation of one-dimensional gratings based on a cross-correlation filter

    NASA Astrophysics Data System (ADS)

    Chen, Xiaomei; Koenders, Ludger

    2014-04-01

    If one-dimensional (1D), p-period and arbitrarily structured grating position-related topographical signals coexist with noise, it is difficult to evaluate the pitch practically using the center-of-gravity (CG) method. The Fourier-transform-based (FT) method is the most precise to evaluate pitches; nevertheless, it cannot give the uniformity of pitches. If a cross-correlation filter—a half period of sinusoidal waveform sequence (pT period), cross-correlates with the signals, the noise can be eliminated if pT ≈ p. After cross-correlation filtering, the distance between any two adjacent waveform peaks along the direction perpendicular to 1D grating lines is one pitch value. The pitch evaluation based on the cross-correlation filtering together with the detection of the peak's position is described as the peak detection (PD) method in this paper. The pitch average and uniformity can be calculated by using the PD method. The computer simulation has indicated that the average of pitch deviations from the true pitch and the pitch variations are less than 0.2% and 0.2% for the sinusoidal and rectangular waveform signals with up to 50% uniform white noise, less than 0.1% and 1% for the sinusoidal and rectangular waveform signals and 0.6% and 2.5% for the triangular waveform signal if three waveform signals are mixed with Gaussian white, binomial and Bernoulli noise up to 50% in standard deviation, one probability and trial probability, respectively. As examples, a highly oriented pyrolytic graphite (HOPG) with a 0.246 nm distance between second nearest neighbour atoms and a 1D grating with 3000 nm nominal pitch are measured by a ultra-high vacuum scanning tunneling microscope (UHV STM) and a metrological atomic force microscope (AFM), respectively. After the position-related topographical signals are cross-correlation filtered, the 0.240 and 3004.11 nm pitches calculated by using the PD method are very close to the 0.240 and 3003.34 nm results evaluated by the FT

  7. Contribution of breathing frequency and inhalation flow rate on performance of N95 filtering facepiece respirators.

    PubMed

    Mahdavi, Alireza; Bahloul, Ali; Haghighat, Fariborz; Ostiguy, Claude

    2014-03-01

    The investigation of particle penetration through filtering facepiece respirators under cyclic flows is very necessary because cyclic flows represent actual breathing flow patterns. This article reports the development of a procedure to investigate the individual impact of breathing frequency and flow rate on the performance of N95 filtering facepiece respirators. Experiments were performed for two peak inhalation flows (PIFs; 135 and 360 l min(-1)) and two breathing frequencies [24 and 42 breaths per minute (BPM)] for a total of four cyclic flows (Flow A: 135 l min(-1) and 24 BPM; Flow B: 135 l min(-1) and 42 BPM; Flow C: 360 l min(-1) and 24 BPM; and Flow D: 360 l min(-1) and 42 BPM). Each experiment was performed using two different set-ups: the first set-up included both inhalations and exhalations through the filter media and test chamber, while with the second set-up, only inhalation flows were considered. The results showed that, for the most penetrating particle size range, an increase in both PIF and breathing frequency could potentially enhance the penetration with both set-ups; however, the effect of PIF was observed to be much more pronounced than that of frequency. The results indicated that with both set-ups, when the PIF was increased from 135 to 360 l min(-1) (for the given frequency: 24 or 42 BPM), an increase of up to 139-152% in penetration was observed. On the other hand, only a 10-16% increase in penetration occurred when the frequency was changed from 24 to 42 BPM (for a given PIF: 135 or 360 l min(-1)). This suggests that, from low to high respiratory efforts, a huge portion of penetration enhancement is due to PIF variations and only a small portion is contributed by frequency variations. PMID:24148765

  8. Longitudinal cross sectional mixing images of the pipe flow with periodical branching flow injections

    NASA Astrophysics Data System (ADS)

    Ueda, Toshihisa; Sunho, You; Higuchi, Naotaka

    2008-11-01

    Effect of periodical injection of branching flows on the mixing in a pipe flow is experimentally investigated. Glycerin is used as a working fluid. The glycerin flows in a steady state condition in the main flow pipe while the branching flow is injected periodically from three pipes equipped normal to the main flow pipe. The longitudinal cross sectional image of the mixing of main flow and branching flows is visualized by LIF method, inserting the Rodamine B in the first branching flow. When only one branching flow is periodically injected, the fluid injected from the side flow pipe is stretched and folded by the parabolic laminar flow velocity profile and then the length of the boundary increases linearly. When branching flow is injected from multiple side flow pipe, the mixing pattern becomes more complicated. As a result, the length of the boundary increases more rapidly compared to the linear increase. The results suggest that the multiple branching flow injection enhances the mixing although no element is inserted in the pipe.

  9. Performance of Improved High-Order Filter Schemes for Turbulent Flows with Shocks

    NASA Technical Reports Server (NTRS)

    Kotov, Dmitry Vladimirovich; Yee, Helen M C.

    2013-01-01

    The performance of the filter scheme with improved dissipation control ? has been demonstrated for different flow types. The scheme with local ? is shown to obtain more accurate results than its counterparts with global or constant ?. At the same time no additional tuning is needed to achieve high accuracy of the method when using the local ? technique. However, further improvement of the method might be needed for even more complex and/or extreme flows.

  10. Effects of Temperature, Humidity and Air Flow on Fungal Growth Rate on Loaded Ventilation Filters.

    PubMed

    Tang, W; Kuehn, T H; Simcik, Matt F

    2015-01-01

    This study compares the fungal growth ratio on loaded ventilation filters under various temperature, relative humidity (RH), and air flow conditions in a controlled laboratory setting. A new full-size commercial building ventilation filter was loaded with malt extract nutrients and conidia of Cladosporium sphaerospermum in an ASHRAE Standard 52.2 filter test facility. Small sections cut from this filter were incubated under the following conditions: constant room temperature and a high RH of 97%; sinusoidal temperature (with an amplitude of 10°C, an average of 23°C, and a period of 24 hr) and a mean RH of 97%; room temperature and step changes between 97% and 75% RH, 97% and 43% RH, and 97% and 11% RH every 12 hr. The biomass on the filter sections was measured using both an elution-culture method and by ergosterol assay immediately after loading and every 2 days up to 10 days after loading. Fungal growth was detected earlier using ergosterol content than with the elution-culture method. A student's t-test indicated that Cladosporium sphaerospermum grew better at the constant room temperature condition than at the sinusoidal temperature condition. By part-time exposure to dry environments, the fungal growth was reduced (75% and 43% RH) or even inhibited (11% RH). Additional loaded filters were installed in the wind tunnel at room temperature and an RH greater than 95% under one of two air flow test conditions: continuous air flow or air flow only 9 hr/day with a flow rate of 0.7 m(3)/s (filter media velocity 0.15 m/s). Swab tests and a tease mount method were used to detect fungal growth on the filters at day 0, 5, and 10. Fungal growth was detected for both test conditions, which indicates that when temperature and relative humidity are optimum, controlling the air flow alone cannot prevent fungal growth. In real applications where nutrients are less sufficient than in this laboratory study, fungal growth rate may be reduced under the same operating conditions.

  11. Radial Flow Fludized Filter Finds Niche as a Pretreatment System for Surface Water in Small Communities

    EPA Science Inventory

    An emerging technology called radial flow fluidized filter (R3f) has been developed as a low cost simplistic filtration technology for small communities of less than 10,000 people. Fouling is a major impediment to the sustainability of membrane technology particularly for small ...

  12. Cross-terminator flow in the ionosphere of Mars

    NASA Astrophysics Data System (ADS)

    Fränz, Markus; Dubinin, Eduard; Nielsen, Erling; Angsmann, Anne; Woch, Joachim; Barabash, Stas; Lundin, Rickard; Fedorov, Andrei

    2010-05-01

    The upper ionospheres of Mars and Venus are permeated by the magnetic fields induced by the solar wind. It is a long-standing question wether these fields can put the dense ionospheric plasma into motion. If so, the cross-terminator flow of the upper ionosphere could explain a significant part of the ion escape from the planets atmospheres. But it has been technically very challenging to measure the ion flow at energies below 20eV. The only such measurements have been made by the ORPA instrument of the Pioneer Venus Orbiter reporting speeds of 1-5km/s for O+ ions at Venus above 300km altitude at the terminator (Knudsen et al, GRL 1982). Since these observations could never be confirmed by other instruments they have been debated. We here report on new measurements of the cross-terminator ion flow at Mars by the ASPERA 3 experiment onboard Mars Express with support from the MARSIS radar experiment which confirm O+ flow speeds of around 6km/s with fluxes of 1.2 × 109/cm2s. We also discuss the complicated influence of the spacecraft potential on low energy measurements. We discuss the implication of these new observation for ion escape and possible extensions of the analysis to dayside observations which might allow us to infer the flow structure imposed by the induced magnetic field.

  13. Numerical simulation of flow in a horizontal channel with multiple cross-flow inlets

    NASA Astrophysics Data System (ADS)

    Jha, Pranab N.; Smith, Chuck; Metcalfe, Ralph W.

    2014-11-01

    Flow in a horizontal channel with multiple cross-flow inlets was studied numerically. Based on Reynolds and Mach number analysis of data obtained from a horizontal natural gas well having 31 completion stages, measured at two different times in the production cycle, it was determined that an incompressible flow model may be applied to study a large fraction of the wellbore. Using five cross-flow inlets, the existence of three basic flow regimes - trickle flow, partially blocked flow and fully blocked flow - were identified with respect to the blocking of upstream inlets by the downstream ones. The existence of these flow regimes is consistent with field data. A lumped-parameter model for pressure drop was used to simulate large axial distances between two inlets. A pressure boundary condition was employed at each inlet to simulate a linearly depleting reservoir. This was used to study the dynamic interaction between the inlets in the channel. The characteristic time scales related to the transient depletion were identified and analyzed. The transition of flow regimes is consistent with the trends observed from field data and gives an insight into the behavior of horizontal wells. Supported in part by Apache Corp., Houston.

  14. Demonstration and Analysis of Filtered Rayleigh Scattering Flow Field Diagnostic System

    NASA Technical Reports Server (NTRS)

    Forkey, Joseph N.; Lempert, Walter R.; Miles, Richard B.

    1996-01-01

    Filtered Rayleigh Scattering (FRS) is a diagnostic technique which measures velocity, temperature, and pressure by determining Doppler shift, total intensity, and spectral line shape of laser induced Rayleigh-Brillouin scattering. In the work reported here, this is accomplished by using a narrow line width, injection seeded Nd-YAG laser sheet to induce Rayleigh-Brillouin scattering from a gas flow. This light is passed through an optical notch filter, and transmitted light is imaged onto an intensified charge coupled display (CCD) camera. By monitoring the grayscale value at a particular pixel while the laser frequency is tuned, the convolution between the Rayleigh-Brillouin scattering profile and the filter transmission profile is attained. Since the filter profile can be independently measured, it can be deconvolved from the measuring signal, yielding the Rayleigh-Brillouin scattering profile. From this profile, flow velocity, temperature, and pressure are determined. In this paper the construction and characterization of the optical notch filter and a newly developed frequency apparatus are discussed.

  15. On the structural limitations of recursive digital filters for base flow estimation

    NASA Astrophysics Data System (ADS)

    Su, Chun-Hsu; Costelloe, Justin F.; Peterson, Tim J.; Western, Andrew W.

    2016-06-01

    Recursive digital filters (RDFs) are widely used for estimating base flow from streamflow hydrographs, and various forms of RDFs have been developed based on different physical models. Numerical experiments have been used to objectively evaluate their performance, but they have not been sufficiently comprehensive to assess a wide range of RDFs. This paper extends these studies to understand the limitations of a generalized RDF method as a pathway for future field calibration. Two formalisms are presented to generalize most existing RDFs, allowing systematic tuning of their complexity. The RDFs with variable complexity are evaluated collectively in a synthetic setting, using modeled daily base flow produced by Li et al. (2014) from a range of synthetic catchments simulated with HydroGeoSphere. Our evaluation reveals that there are optimal RDF complexities in reproducing base flow simulations but shows that there is an inherent physical inconsistency within the RDF construction. Even under the idealized setting where true base flow data are available to calibrate the RDFs, there is persistent disagreement between true and estimated base flow over catchments with small base flow components, low saturated hydraulic conductivity of the soil and larger surface runoff. The simplest explanation is that low base flow "signal" in the streamflow data is hard to distinguish, although more complex RDFs can improve upon the simpler Eckhardt filter at these catchments.

  16. Investigation of non-symmetric jets in cross flow

    NASA Astrophysics Data System (ADS)

    Yu, Fan-Ming

    1987-05-01

    Non-symmetric jets in crossflow were studied with various jet geometries, jet orientations, jet characteristics, and jet to crossflow velocity ratios. Four different cross-section geometry jets were studied and compared with a circular jet with identical jet port cross-sectional area. Standard dye and laser induced fluorescent flow visualization techniques were used to identify the existence of various vortices in the flow field. Among the many forms of secondary vortices produced, three major vortex systems were identified: main jet vortices, wake vortices, and spinoff vortices. A reconstruction of the asymmetric flow field based on observations and its evolution and relationships with established symmetric jets in the crossflow were made. The large scale rolled-up vortex structure which was found at low jet to crossflow velocity ratio is very similar to the hair-pin vortex structure. This observation provides a potential research tool on the study of the structure of turbulent boundary layers. Unsteady jets created by pulsation of the jet flow at low pulsation frequencies give the increase of the depth of penetration. However, the introducing of swirl into jets by passive methods reduces the depth of penetration.

  17. The role of pressure drop and flow redistribution on modeling mercury control using sorbent injection in baghouse filters

    SciTech Connect

    Joseph R.V. Flora; Richard A. Hargis; William J. O'Dowd; Andrew Karash; Henry W. Pennline; Radisav D. Vidic

    2006-03-15

    A mathematical model based on simple cake filtration theory was coupled to a previously developed two-stage mathematical model for mercury (Hg) removal from coal combustion using powdered activated carbon injection upstream of a baghouse filter. Values of the average permeability of the filter cake and the filter resistance extracted from the model were 4.4 x 10{sup -13}m{sup 2} and 2.5 x 10{sup -4}m{sup -1}, respectively. The flow is redistributed during partial cleaning of the filter, with flows higher across the newly cleaned filter section. The calculated average Hg removal efficiency from the baghouse is lower because of the high mass flux of Hg exiting the filter in the newly cleaned section. The model shows that calculated average Hg removal is affected by permeability, filter resistance, fraction of the baghouse cleaned, and cleaning interval. 17 refs., 8 figs., 2 tabs.

  18. Analysis of up-flow aerated biological activated carbon filter technology in drinking water treatment.

    PubMed

    Lu, Shaoming; Liu, Jincui; Li, Shaowen; Biney, Elizabeth

    2013-01-01

    Problems have been found in the traditional post-positioned down-flow biological activated carbon filter (DBACF), such as microorganism leakage and low biodegradability. A pilot test was carried out to place a BACF between the sediment tank and the sand filter; a new technology of dual media up-flow aerated biological activated carbon filter (UBACF) was developed. Results showed that in terms of the new process, the up-flow mode was better than the down-flow. Compared with the DBACF, the problem of microorganism leakage could be well resolved with the UBACF process by adding disinfectant before the sand filtration, and a similar adsorption effect could be obtained. For the tested raw water, the COD(Mn) and NH3-N removal rate was 54.6% and 85.0%, respectively, similar to the waterworks with the DBACF process. The UBACF greatly enhanced oxygen supply capability and mass transfer rate via aeration, and the NH3-N removal ability was significantly improved from 1.5 mg/L to more than 3 mg/L. Influent to the UBACF with higher turbidity could be coped with through the primary filtration of the ceramisite layer combined with fluid-bed technology, which gave the carbon bed a low-turbidity environment of less than 1.0 NTU. The backwashing parameters and carbon abrasion rate of the two processes were almost the same.

  19. Model simulation and experiments of flow and mass transport through a nano-material gas filter

    SciTech Connect

    Yang, Xiaofan; Zheng, Zhongquan C.; Winecki, Slawomir; Eckels, Steve

    2013-11-01

    A computational model for evaluating the performance of nano-material packed-bed filters was developed. The porous effects of the momentum and mass transport within the filter bed were simulated. For the momentum transport, an extended Ergun-type model was employed and the energy loss (pressure drop) along the packed-bed was simulated and compared with measurement. For the mass transport, a bulk dsorption model was developed to study the adsorption process (breakthrough behavior). Various types of porous materials and gas flows were tested in the filter system where the mathematical models used in the porous substrate were implemented and validated by comparing with experimental data and analytical solutions under similar conditions. Good agreements were obtained between experiments and model predictions.

  20. A Fast Network Flow Model is used in conjunction with Measurements of Filter Permeability to calculate the Performance of Hot Gas Filters

    SciTech Connect

    VanOsdol, J.G.; Chiang, T-K.

    2002-09-19

    Two different technologies that are being considered for generating electric power on a large scale by burning coal are Pressurized Fluid Bed Combustion (PFBC) systems and Integrated Gasification and Combined Cycle (IGCC) systems. Particulate emission regulations that have been proposed for future systems may require that these systems be fitted with large scale Hot Gas Clean-Up (HGCU) filtration systems that would remove the fine particulate matter from the hot gas streams that are generated by PFBC and IGCC systems. These hot gas filtration systems are geometrically and aerodynamically complex. They typically are constructed with large arrays of ceramic candle filter elements (CFE). The successful design of these systems require an accurate assessment of the rate at which mechanical energy of the gas flow is dissipated as it passes through the filter containment vessel and the individual candle filter elements that make up the system. Because the filtration medium is typically made of a porous ceramic material having open pore sizes that are much smaller than the dimensions of the containment vessel, the filtration medium is usually considered to be a permeable medium that follows Darcy's law. The permeability constant that is measured in the lab is considered to be a function of the filtration medium only and is usually assumed to apply equally to all the filters in the vessel as if the flow were divided evenly among all the filter elements. In general, the flow of gas through each individual CFE will depend not only on the geometrical characteristics of the filtration medium, but also on the local mean flows in the filter containment vessel that a particular filter element sees. The flow inside the CFE core, through the system manifolds, and inside the containment vessel itself will be coupled to the flow in the filter medium by various Reynolds number effects. For any given filter containment vessel, since the mean flows are different in different locations

  1. High efficiency collection of fly ash in a parallel flow, moving granular bed filter. Paper 81. 64. 2

    SciTech Connect

    Sundstrom, G.; Leith, D.

    1981-01-01

    A moving granular bed filter which removes particles from hot gas streams was modified in order to reduce resuspension at the gas outlet. Cocurrent beds offer several advantages for fly ash collection, particularly large particles and agglomerates. This device is known as a parallel flow filter, as gas first flows vertically downward through a cocurrent bed, and then turns and flows vertically upward through a countercurrent bed. 15 refs.

  2. Oxygen profile and clogging in vertical flow sand filters for on-site wastewater treatment.

    PubMed

    Petitjean, A; Forquet, N; Boutin, C

    2016-04-01

    13 million people (about 20% of the population) use on-site wastewater treatment in France. Buried vertical sand filters are often built, especially when the soil permeability is not sufficient for septic tank effluent infiltration in undisturbed soil. Clogging is one of the main problems deteriorating the operation of vertical flow filters for wastewater treatment. The extent of clogging is not easily assessed, especially in buried vertical flow sand filters. We suggest examining two possible ways of detecting early clogging: (1) NH4-N/NO3-N outlet concentration ratio, and (2) oxygen measurement within the porous media. Two pilot-scale filters were equipped with probes for oxygen concentration measurements and samples were taken at different depths for pollutant characterization. Influent and effluent grab-samples were taken three times a week. The systems were operated using batch-feeding of septic tank effluent. Qualitative description of oxygen transfer processes under unclogged and clogged conditions is presented. NH4-N outlet concentration appears to be useless for early clogging detection. However, NO3-N outlet concentration and oxygen content allows us to diagnose the early clogging of the system.

  3. Oxygen profile and clogging in vertical flow sand filters for on-site wastewater treatment.

    PubMed

    Petitjean, A; Forquet, N; Boutin, C

    2016-04-01

    13 million people (about 20% of the population) use on-site wastewater treatment in France. Buried vertical sand filters are often built, especially when the soil permeability is not sufficient for septic tank effluent infiltration in undisturbed soil. Clogging is one of the main problems deteriorating the operation of vertical flow filters for wastewater treatment. The extent of clogging is not easily assessed, especially in buried vertical flow sand filters. We suggest examining two possible ways of detecting early clogging: (1) NH4-N/NO3-N outlet concentration ratio, and (2) oxygen measurement within the porous media. Two pilot-scale filters were equipped with probes for oxygen concentration measurements and samples were taken at different depths for pollutant characterization. Influent and effluent grab-samples were taken three times a week. The systems were operated using batch-feeding of septic tank effluent. Qualitative description of oxygen transfer processes under unclogged and clogged conditions is presented. NH4-N outlet concentration appears to be useless for early clogging detection. However, NO3-N outlet concentration and oxygen content allows us to diagnose the early clogging of the system. PMID:26775157

  4. Vibration effect on cross-flow and co-flow focusing mechanism for droplet generation

    NASA Astrophysics Data System (ADS)

    Salari, Alinaghi; Dalton, Colin

    2015-03-01

    Microbubbles are widely used in many industries such as water treatment, drug coating, and ultrasonic contrast agents. Cross-flow focusing and co-flow focusing are considered basic mechanisms used for microbubble generation. Typically, to achieve micron-sized droplets requires structure dimensions in the same order of magnitude of the desired droplet sizes. In this paper we report a method of applying an external vibration to a cross-flow and co-flow focusing structure, which allows for smaller droplets to be generated. The junction dimension was 700×400 μm, and the channel width was 800 μm. The two assumed fluids are selected in a way that the Capillary number is high (Ca>10) to make use of necking effect occurred in the downstream. Linear vibration was exerted on the microchannel structure in the direction of central flow. A 2D structure was simulated using finite element software, and the numerical approach was then verified by comparing the experimental data of a typical cross-flow focusing structure taken from our previous study with the corresponding simulation assuming the same parameters. The results show that although the droplet generation regime depends on flow ratio (Qa/Qw) and vibration parameter (ampl×freq), Capillary number also has a significant effect on the regime. Briefly, applying a low-cost linear vibration to the conventional flow focusing structures can be used as an accurate controlling technique for increasing the chance of droplet generation. In fact, vibration motion can change the flow regime and breakup mechanism. It can also change the breakup point at which the droplets are formed.

  5. Alternative filter media for phosphorous removal in a horizontal subsurface flow constructed wetland.

    PubMed

    Vohla, Christina; Põldvere, Elar; Noorvee, Alar; Kuusemets, Valdo; Mander, Ulo

    2005-01-01

    During the study period from 1997 to 2002 the purification efficiency of phosphorus in the horizontal subsurface flow (HSSF) constructed wetland (CW) in Kodijärve, has been quite high (63-95%). However, slowly increasing trend in outlet P concentrations and decreasing annual P removal rate are obviously the indicators that show possible saturation processes in filter media. To search for potential filter media with high phosphorus sorption capacity, sorption characteristics and particle size distribution of several local sands, gravels, glauconite-sandstone, LWA, and calcareous waste products from oil-shale industry were investigated. The average P sorption capacity for best materials (crashed ash block, oil, shale fly ash and the sediment from oil shale ash plateau) was higher than 96% and estimated design capacity was around 4-5 g P kg(-1). According to results, sediment from oil shale ash plateau was considered as perspective filter media for P retention. In Summer 2002 experimental sedimentation filter, filled with the sediment from oil shale ash plateau, was installed in the outlet from the Kodijärve HSSF CW. According to preliminary results the average P removal in the sedimentation filter was 52%. PMID:15921280

  6. A new way to apply ultrasound in cross-flow ultrafiltration: application to colloidal suspensions.

    PubMed

    Hengl, N; Jin, Y; Pignon, F; Baup, S; Mollard, R; Gondrexon, N; Magnin, A; Michot, L; Paineau, E

    2014-05-01

    A new coupling of ultrasound device with membrane process has been developed in order to enhance cross-flow ultrafiltration of colloidal suspensions usually involved in several industrial applications included bio and agro industries, water and sludge treatment. In order to reduce mass transfer resistances induced by fouling and concentration polarization, which both are main limitations in membrane separation process continuous ultrasound is applied with the help of a vibrating blade (20 kHz) located in the feed channel all over the membrane surface (8mm between membrane surface and the blade). Hydrodynamic aspects were also taking into account by the control of the rectangular geometry of the feed channel. Three colloidal suspensions with different kinds of colloidal interaction (attractive, repulsive) were chosen to evaluate the effect of their physico-chemical properties on the filtration. For a 90 W power (20.5 W cm(-2)) and a continuous flow rate, permeation fluxes are increased for each studied colloidal suspension, without damaging the membrane. The results show that the flux increase depends on the initial structural properties of filtered dispersion in terms of colloidal interaction and spatial organizations. For instance, a Montmorillonite Wyoming-Na clay suspension was filtered at 1.5 × 10(5)Pa transmembrane pressure. Its permeation flux is increased by a factor 7.1, from 13.6 L m(-2)h(-1) without ultrasound to 97 L m(-2)h(-1) with ultrasound.

  7. Laser Doppler anemometry and fibreoptical spatial filter anemometry - A comparison for the multiphase flow measurement

    NASA Astrophysics Data System (ADS)

    Petrak, D.; Haedrich, T.

    The paper presents a comparison between the fiber-optical spatial filter anemometry (FOA) and LDA for the particle velocity measurement in a two-phase flow. An LDA two beam anemometer and a differential-type optical fiber array spatial filter were used for the velocity measurements on glass particles with a mean diameter of 116 microns in a horizontal channel air flow. Two different probe pipe constructions were investigated. In general the results show that the FOA-probe signals have a low signal-to-noise ratio in comparison with the LDA-signals and that the mean FOA-particle velocity is smaller than the mean LDA-particle velocity. A FOA-system with a probe construction like a Pitot tube is preferred for the application.

  8. Three-dimensional computations of cross-flow injection and combustion in a supersonic flow

    NASA Technical Reports Server (NTRS)

    Carpenter, M. H.

    1989-01-01

    A low-storage version of the SPARK3D code which is based on the temporally second-order accurate MacCormack (1969) explicit scheme is used to solve the governing equations for three-dimensional chemically reacting flows with finite-rate chemistry. The code includes a fourth-order compact spatial scheme capable of providing higher order spatial accuracy, and it is used to study two-dimensional linear advection, two-dimensional Euler flow, and three-dimensional viscous flow. Also considered are the injection, mixing, and combustion of hydrogen in a supersonic cross stream.

  9. Fibrous filter efficiency and pressure drop in the viscous-inertial transition flow regime.

    SciTech Connect

    Sanchez, Andres L.; Brockmann, John E.; Dellinger, Jennifer Gwynne; Lucero, Daniel A.; Hubbard, Joshua A.; Servantes, Brandon Lee

    2011-10-01

    Fibrous filter pressure drop and aerosol collection efficiency were measured at low air pressures (0.2 to 0.8 atm) and high face velocities (5 to 20 meters per second) to give fiber Reynolds numbers in the viscous-inertial transition flow regime (1 to 16). In this regime, contemporary filtration theory based on Kuwabara's viscous flow through an ensemble of fibers under-predicts single fiber impaction by several orders of magnitude. Streamline curvature increases substantially as inertial forces become dominant. Dimensionless pressure drop measurements followed the viscous-inertial theory of Robinson and Franklin rather than Darcy's linear pressure-velocity relationship (1972). Sodium chloride and iron nano-agglomerate test aerosols were used to evaluate the effects of particle density and shape factor. Total filter efficiency collapsed when plotted against the particle Stokes and fiber Reynolds numbers. Efficiencies were then fitted with an impactor type equation where the cutpoint Stokes number and a steepness parameter described data well in the sharply increasing portion of the curve (20% to 80% efficiency). The cutpoint Stokes number was a linearly decreasing function of fiber Reynolds number. Single fiber efficiencies were calculated from total filter efficiencies and compared to contemporary viscous flow impaction theory (Stechkina et al. 1969), and numerical simulations from the literature. Existing theories under-predicted measured single fiber efficiencies although the assumption of uniform flow conditions for each successive layer of fibers is questionable; the common exponential relationship between single fiber efficiency and total filter efficiency may not be appropriate in this regime.

  10. Large particle penetration through N95 respirator filters and facepiece leaks with cyclic flow.

    PubMed

    Cho, Kyungmin Jacob; Reponen, Tiina; McKay, Roy; Shukla, Rakesh; Haruta, Hiroki; Sekar, Padmini; Grinshpun, Sergey A

    2010-01-01

    The aim of this study was to investigate respirator filter and faceseal penetration of particles representing bacterial and fungal spore size ranges (0.7-4 mum). First, field experiments were conducted to determine workplace protection factors (WPFs) for a typical N95 filtering facepiece respirator (FFR). These data (average WPF = 515) were then used to position the FFR on a manikin to simulate realistic donning conditions for laboratory experiments. Filter penetration was also measured after the FFR was fully sealed on the manikin face. This value was deducted from the total penetration (obtained from tests with the partially sealed FFR) to determine the faceseal penetration. All manikin experiments were repeated using three sinusoidal breathing flow patterns corresponding to mean inspiratory flow rates of 15, 30, and 85 l min(-1). The faceseal penetration varied from 0.1 to 1.1% and decreased with increasing particle size (P < 0.001) and breathing rate (P < 0.001). The fractions of aerosols penetrating through the faceseal leakage varied from 0.66 to 0.94. In conclusion, even for a well-fitting FFR respirator, most particle penetration occurs through faceseal leakage, which varies with breathing flow rate and particle size.

  11. A novel retinal vessel extraction algorithm based on matched filtering and gradient vector flow

    NASA Astrophysics Data System (ADS)

    Yu, Lei; Xia, Mingliang; Xuan, Li

    2013-10-01

    The microvasculature network of retina plays an important role in the study and diagnosis of retinal diseases (age-related macular degeneration and diabetic retinopathy for example). Although it is possible to noninvasively acquire high-resolution retinal images with modern retinal imaging technologies, non-uniform illumination, the low contrast of thin vessels and the background noises all make it difficult for diagnosis. In this paper, we introduce a novel retinal vessel extraction algorithm based on gradient vector flow and matched filtering to segment retinal vessels with different likelihood. Firstly, we use isotropic Gaussian kernel and adaptive histogram equalization to smooth and enhance the retinal images respectively. Secondly, a multi-scale matched filtering method is adopted to extract the retinal vessels. Then, the gradient vector flow algorithm is introduced to locate the edge of the retinal vessels. Finally, we combine the results of matched filtering method and gradient vector flow algorithm to extract the vessels at different likelihood levels. The experiments demonstrate that our algorithm is efficient and the intensities of vessel images exactly represent the likelihood of the vessels.

  12. Large particle penetration through N95 respirator filters and facepiece leaks with cyclic flow.

    PubMed

    Cho, Kyungmin Jacob; Reponen, Tiina; McKay, Roy; Shukla, Rakesh; Haruta, Hiroki; Sekar, Padmini; Grinshpun, Sergey A

    2010-01-01

    The aim of this study was to investigate respirator filter and faceseal penetration of particles representing bacterial and fungal spore size ranges (0.7-4 mum). First, field experiments were conducted to determine workplace protection factors (WPFs) for a typical N95 filtering facepiece respirator (FFR). These data (average WPF = 515) were then used to position the FFR on a manikin to simulate realistic donning conditions for laboratory experiments. Filter penetration was also measured after the FFR was fully sealed on the manikin face. This value was deducted from the total penetration (obtained from tests with the partially sealed FFR) to determine the faceseal penetration. All manikin experiments were repeated using three sinusoidal breathing flow patterns corresponding to mean inspiratory flow rates of 15, 30, and 85 l min(-1). The faceseal penetration varied from 0.1 to 1.1% and decreased with increasing particle size (P < 0.001) and breathing rate (P < 0.001). The fractions of aerosols penetrating through the faceseal leakage varied from 0.66 to 0.94. In conclusion, even for a well-fitting FFR respirator, most particle penetration occurs through faceseal leakage, which varies with breathing flow rate and particle size. PMID:19700488

  13. Enhanced Kalman Filtering for a 2D CFD NS Wind Farm Flow Model

    NASA Astrophysics Data System (ADS)

    Doekemeijer, B. M.; van Wingerden, J. W.; Boersma, S.; Pao, L. Y.

    2016-09-01

    Wind turbines are often grouped together for financial reasons, but due to wake development this usually results in decreased turbine lifetimes and power capture, and thereby an increased levelized cost of energy (LCOE). Wind farm control aims to minimize this cost by operating turbines at their optimal control settings. Most state-of-the-art control algorithms are open-loop and rely on low fidelity, static flow models. Closed-loop control relying on a dynamic model and state observer has real potential to further decrease wind's LCOE, but is often too computationally expensive for practical use. In this paper two time-efficient Kalman filter (KF) variants are outlined incorporating the medium fidelity, dynamic flow model “WindFarmSimulator” (WFSim). This model relies on a discretized set of Navier-Stokes equations in two dimensions to predict the flow in wind farms at low computational cost. The filters implemented are an Ensemble KF and an Approximate KF. Simulations in which a high fidelity simulation model represents the true wind farm show that these filters are 101 —102 times faster than a regular KF with comparable or better performance, correcting for wake dynamics that are not modeled in WFSim (noticeably, wake meandering and turbine hub effects). This is a first big step towards real-time closed-loop control for wind farms.

  14. Acoustic cross-correlation flowmeter for solid-gas flow

    NASA Astrophysics Data System (ADS)

    Sheen, S. H.; Raptis, A. C.

    1984-05-01

    An apparatus for measuring particle velocity in a solid-gas flow within a pipe is described. It includes: first and second transmitting transducers for transmitting first and second ultrasonic signals into the pipe at first and second locations, respectively, along the pipe; an acoustic decoupler, positioned between said first and second transmitting transducers, for acoustically isolating said first and second signals from one another; first and second detecting transducers for detecting said first and second signals and for generating first and second detected signals; and means for cross-correlating said first and second output signals.

  15. Acoustic cross-correlation flowmeter for solid-gas flow

    DOEpatents

    Sheen, S.H.; Raptis, A.C.

    1984-05-14

    Apparatus for measuring particle velocity in a solid-gas flow within a pipe includes: first and second transmitting transducers for transmitting first and second ultrasonic signals into the pipe at first and second locations, respectively, along the pipe; an acoustic decoupler, positioned between said first and second transmitting transducers, for acoustically isolating said first and second signals from one another; first and second detecting transducers for detecting said first and second signals and for generating first and second detected signals; and means for cross-correlating said first and second output signals.

  16. Acoustic cross-correlation flowmeter for solid-gas flow

    DOEpatents

    Sheen, Shuh-Haw; Raptis, Apostolos C.

    1986-01-01

    Apparatus for measuring particle velocity in a solid-gas flow within a pipe includes: first and second transmitting transducers for transmitting first and second ultrasonic signals into the pipe at first and second locations, respectively, along the pipe; an acoustic decoupler, positioned between said first and second transmitting transducers, for acoustically isolating said first and second signals from one another; first and second detecting transducers for detecting said first and second signals and for generating first and second detected signals in response to said first and second detected signals; and means for cross-correlating said first and second output signals.

  17. Cross Flow Effects on Glaze Ice Roughness Formation

    NASA Technical Reports Server (NTRS)

    Tsao, Jen-Ching

    2004-01-01

    The present study examines the impact of large-scale cross flow on the creation of ice roughness elements on the leading edge of a swept wing under glaze icing conditions. A three-dimensional triple-deck structure is developed to describe the local interaction of a 3 D air boundary layer with ice sheets and liquid films. A linear stability analysis is presented here. It is found that, as the sweep angle increases, the local icing instabilities enhance and the most linearly unstable modes are strictly three dimensional.

  18. Two-, three-, and four-poster jets in cross flow

    NASA Astrophysics Data System (ADS)

    Vukits, Thomas J.; Sullivan, John P.; Murthy, S. N. B.

    1993-01-01

    In connection with the problems of the ingestion of hot exhaust gases in engines of V/STOL and STOVL aircraft in ground effect, a series of studies have been undertaken. Ground impinging, two- and three-poster jets operating in the presence of cross flow were studied. The current paper is divided into two parts. The first part is a comparison of the low speed, two-, three-, and four-poster jet cases, with respect to the flowfield in the region of interaction between the forward and the jet flows. These include cases with mass balanced inlet suction. An analysis of the inlet entry plane of the low speed two- and three-poster jet cases is also given. In the second part, high speed results for a two jet configuration without inlet suction are given. The results are based on quantitative, marker concentration distributions obtained by digitizing video images.

  19. Taylor-Couette flow control by amplitude variation of the inner cylinder cross-section oscillation

    NASA Astrophysics Data System (ADS)

    Oualli, Hamid; Mekadem, Mahmoud; Lebbi, Mohamed; Bouabdallah, Ahcene

    2015-07-01

    The hydrodynamic stability of a viscous fluid flow evolving in an annular space between a rotating inner cylinder with a periodically variable radius and an outer fixed cylinder is considered. The basic flow is axis-symmetric with two counter-rotating vortices each wavelength along the whole filled system length. The numerical simulations are implemented on the commercial Fluent software package, a finite-volume CFD code. It is aimed to make investigation of the early flow transition with assessment of the flow response to radial pulsatile motion superimposed to the inner cylinder cross-section as an extension of a previous developed work in Oualli et al. [H. Oualli, A. Lalaoua, S. Hanchi, A. Bouabdallah, Eur. Phys. J. Appl. Phys. 61, 11102 (2013)] where a comparative controlling strategy is applied to the outer cylinder. The same basic system is considered with similar calculating parameters and procedure. In Oualli et al. [H. Oualli, A. Lalaoua, S. Hanchi, A. Bouabdallah, Eur. Phys. J. Appl. Phys. 61, 11102 (2013)], it is concluded that for the actuated outer cylinder and relatively to the non-controlled case, the critical Taylor number, Tac1, characterizing the first instability onset illustrated by the piled Taylor vortices along the gap, increases substantially to reach a growing rate of 70% when the deforming amplitude is ɛ = 15%. Interestingly, when this controlling strategy is applied to the inner cylinder cross-section with a slight modification of the actuating law, this tendency completely inverts and the critical Taylor number decreases sharply from Tac1 = 41.33 to Tac1 = 17.66 for ɛ = 5%, corresponding to a reduction rate of 57%. Fundamentally, this result is interesting and can be interpreted by prematurely triggering instabilities resulting in rapid development of flow turbulence. Practically, important applicative aspects can be met in several industry areas where substantial intensification of transport phenomena (mass, momentum and heat) is

  20. Recovery Act - Refinement of Cross Flow Turbine Airfoils

    SciTech Connect

    McEntee, Jarlath

    2013-08-30

    Ocean Renewable Power Company, LLC (ORPC) is a global leader in hydrokinetic technology and project development. ORPC develops hydrokinetic power systems and eco-conscious projects that harness the power of oceans and rivers to create clean, predictable renewable energy. ORPC’s technology consists of a family of modular hydrokinetic power systems: the TidGen® Power System, for use at shallow to medium-depth tidal sites; the RivGen™ Power System, for use at river and estuary sites; and the OCGen® Power System, presently under development, for use at deep tidal and offshore ocean current sites. These power systems convert kinetic energy in moving water into clean, renewable, grid-compatible electric power. The core technology component for all ORPC power systems is its patented turbine generator unit (TGU). The TGU uses proprietary advanced design cross flow (ADCF) turbines to drive an underwater permanent magnet generator mounted at the TGU’s center. It is a gearless, direct-drive system that has the potential for high reliability, requires no lubricants and releases no toxins that could contaminate the surrounding water. The hydrokinetic industry shows tremendous promise as a means of helping reduce the U.S.’s use of fossil fuels and dependence on foreign oil. To exploit this market opportunity, cross-flow hydrokinetic devices need to advance beyond the pre-commercial state and more systematic data about the structure and function of cross-flow hydrokinetic devices is required. This DOE STTR project, “Recovery Act - Refinement of Cross Flow Turbine Airfoils,” refined the cross-flow turbine design process to improve efficiency and performance and developed turbine manufacturing processes appropriate for volume production. The project proposed (1) to overcome the lack of data by extensively studying the properties of cross flow turbines, a particularly competitive design approach for extracting hydrokinetic energy and (2) to help ORPC mature its pre

  1. Solid oxide fuel cell having compound cross flow gas patterns

    DOEpatents

    Fraioli, A.V.

    1983-10-12

    A core construction for a fuel cell is disclosed having both parallel and cross flow passageways for the fuel and the oxidant gases. Each core passageway is defined by electrolyte and interconnect walls. Each electrolyte wall consists of cathode and anode materials sandwiching an electrolyte material. Each interconnect wall is formed as a sheet of inert support material having therein spaced small plugs of interconnect material, where cathode and anode materials are formed as layers on opposite sides of each sheet and are electrically connected together by the interconnect material plugs. Each interconnect wall in a wavy shape is connected along spaced generally parallel line-like contact areas between corresponding spaced pairs of generally parallel electrolyte walls, operable to define one tier of generally parallel flow passageways for the fuel and oxidant gases. Alternate tiers are arranged to have the passageways disposed normal to one another. Solid mechanical connection of the interconnect walls of adjacent tiers to the opposite sides of the common electrolyte wall therebetween is only at spaced point-like contact areas, 90 where the previously mentioned line-like contact areas cross one another.

  2. Solid oxide fuel cell having compound cross flow gas patterns

    DOEpatents

    Fraioli, Anthony V.

    1985-01-01

    A core construction for a fuel cell is disclosed having both parallel and cross flow passageways for the fuel and the oxidant gases. Each core passageway is defined by electrolyte and interconnect walls. Each electrolyte wall consists of cathode and anode materials sandwiching an electrolyte material. Each interconnect wall is formed as a sheet of inert support material having therein spaced small plugs of interconnect material, where cathode and anode materials are formed as layers on opposite sides of each sheet and are electrically connected together by the interconnect material plugs. Each interconnect wall in a wavy shape is connected along spaced generally parallel line-like contact areas between corresponding spaced pairs of generally parallel electrolyte walls, operable to define one tier of generally parallel flow passageways for the fuel and oxidant gases. Alternate tiers are arranged to have the passageways disposed normal to one another. Solid mechanical connection of the interconnect walls of adjacent tiers to the opposite sides of the common electrolyte wall therebetween is only at spaced point-like contact areas, 90 where the previously mentioned line-like contact areas cross one another.

  3. Viable viral efficiency of N95 and P100 respirator filters at constant and cyclic flow.

    PubMed

    Gardner, Paul D; Eshbaugh, Jonathan P; Harpest, Shannon D; Richardson, Aaron W; Hofacre, Kent C

    2013-01-01

    The growing threat of an influenza pandemic presents a unique challenge to healthcare workers, emergency responders, and the civilian population. The Occupational Safety and Health Administration (OSHA) recommends National Institute for Occupational Safety and Health (NIOSH)-approved respirators to provide protection against infectious airborne viruses in various workplace settings. The filtration efficiency of selected NIOSH-approved particulate N95 and P100 filtering facepiece respirators (FFRs) and filter cartridges was investigated against the viable MS2 virus, a non-pathogenic bacteriophage, aerosolized from a liquid suspension. Tests were performed under two cyclic flow conditions (minute volumes of 85 and 135 L/min) and two constant flow rates (85 and 270 L/min). The mean penetrations of viable MS2 through the N95 and P100 FFRs/cartridges were typically less than 2 and 0.03%, respectively, under all flow conditions. All N95 and P100 FFR and cartridge models assessed in this study, therefore, met or exceeded their respective efficiency ratings of 95 and 99.97% against the viable MS2 test aerosol, even under the very high flow conditions. These NIOSH-approved FFRs and particulate respirators equipped with these cartridges can be anticipated to achieve expected levels of protection (consistent with their assigned protection factor) against airborne viral agents, provided that they are properly selected, fitted, worn, and maintained. PMID:24011377

  4. Stability of uniform vertical flow through a close porous filter in the presence of solute immobilization.

    PubMed

    Maryshev, Boris S; Lyubimova, Tatyana P

    2016-06-01

    In the present paper we consider slow filtration of a mixture through a close porous filter. The heavy solute penetrates slowly into the porous filter due to the external vertical filtration flow and diffusion. This process is accompanied by the formation of the domain with heavy fluid near the upper boundary of the filter. The developed stratification, at which the heavy fluid is located above the light fluid, is unstable. When the mass of the heavy fluid exceeds the critical value, one can observe the onset of the Rayleigh-Taylor instability. Due to the above peculiarities we can distinguish between two regimes of vertical filtration: 1) homogeneous seepage and 2) convective filtration. When considering the filtration process it is necessary to take into account the diffusion accompanied by the immobilization effect (or sorption) of the solute. The immobilization is described by the linear MIM (mobile/immobile media) model. It has been shown that the immobilization slows down the process of forming the unstable stratification. The purpose of the paper is to find the stability conditions for homogeneous vertical seepage of he solute into the close porous filter. The linear stability problem is solved using the quasi-static approach. The critical times of instability are estimated. The stability maps are plotted in the space of system parameters. The applicability of quasi-static approach is substantiated by direct numerical simulation of the full nonlinear equations. PMID:27349555

  5. Denitrification in tertiary filtration: application of an up-flow filter.

    PubMed

    Farabegoli, G; Gavasci, R; Lombardi, F; Romani, F

    2003-01-01

    The present paper shows the results obtained through an experimental work performed at the wastewater treatment plant of Rome, aimed at studying the performances of a tertiary filter regarding combined removal of suspended solids, COD, and nitrates. The up-flow sand filter was fed by the effluent coming from the secondary settling tank of the plant. The filter bed height was of 80 cm of silica sand. After a start up period, a study of particulate and soluble COD removal process was made, to establish the need of methanol in the denitrification process. Total COD removal efficiency was 60% on average, 55% due by soluble COD removal and 5% by particulate one. In the last phase of the experimental activity methanol was fed as carbon source, sodium sulfite was supplied to produce anoxic environment within the filter and the denitrification efficiency was studied. Nitrates removal rates after an acclimation period of 10 days increased up to 60%, with an effluent NO3-N of 8 mg/L. Denitrification rate was 2.4 kg/m3 d for water temperatures of 25 degrees C. Regarding methanol demand and biologic kinetics, the biomass yield coefficient was 0.3 kg(COD-X)/kg(me). Consequently 2.7 kg of methanol was required per kilogram of denitrified nitrogen.

  6. Data assimilation for unsaturated flow models with restart adaptive probabilistic collocation based Kalman filter

    NASA Astrophysics Data System (ADS)

    Man, Jun; Li, Weixuan; Zeng, Lingzao; Wu, Laosheng

    2016-06-01

    The ensemble Kalman filter (EnKF) has gained popularity in hydrological data assimilation problems. As a Monte Carlo based method, a sufficiently large ensemble size is usually required to guarantee the accuracy. As an alternative approach, the probabilistic collocation based Kalman filter (PCKF) employs the polynomial chaos expansion (PCE) to represent and propagate the uncertainties in parameters and states. However, PCKF suffers from the so-called "curse of dimensionality". Its computational cost increases drastically with the increasing number of parameters and system nonlinearity. Furthermore, PCKF may fail to provide accurate estimations due to the joint updating scheme for strongly nonlinear models. Motivated by recent developments in uncertainty quantification and EnKF, we propose a restart adaptive probabilistic collocation based Kalman filter (RAPCKF) for data assimilation in unsaturated flow problems. During the implementation of RAPCKF, the important parameters are identified and active PCE basis functions are adaptively selected at each assimilation step; the "restart" scheme is utilized to eliminate the inconsistency between updated model parameters and states variables. The performance of RAPCKF is systematically tested with numerical cases of unsaturated flow models. It is shown that the adaptive approach and restart scheme can significantly improve the performance of PCKF. Moreover, RAPCKF has been demonstrated to be more efficient than EnKF with the same computational cost.

  7. Using the developed cross-flow filtration chip for collecting blood plasma under high flow rate condition and applying the immunoglobulin E detection

    NASA Astrophysics Data System (ADS)

    Yeh, Chia-Hsien; Hung, Chia-Wei; Wu, Chun-Han; Lin, Yu-Cheng

    2014-09-01

    This paper presents a cross-flow filtration chip for separating blood cells (white blood cells, red blood cells, and platelets) and obtaining blood plasma from human blood. Our strategy is to flow the sample solution in parallel to the membrane, which can generate a parallel shear stress to remove the clogging microparticles on the membrane, so the pure sample solution is obtained in the reservoir. The cross-flow filtration chip includes a cross-flow layer, a Ni-Pd alloy micro-porous membrane, and a reservoir layer. The three layers are packaged in a polymethylmethacrylate (PMMA) frame to create the cross-flow filtration chip. Various dilutions of the blood sample (original, 2 × , 3 × , 5 × , and 10×), pore sizes with different diameters (1 µm, 2 µm, 4 µm, 7 µm, and 10 µm), and different flow rates (1 mL/min, 3 mL/min, 5 mL/min, 7 mL/min, and 10 mL/min) are tested to determine their effects on filtration percentage. The best filtration percentage is 96.2% when the dilution of the blood sample is 10 × , the diameter of pore size of a Ni-Pd alloy micro-porous membrane is 2 µm, and the flow rate is 10 mL/min. Finally, for the clinical tests of the immunoglobulin E (IgE) concentration, the cross-flow filtration chip is used to filter the blood of the allergy patients to obtain the blood plasma. This filtered blood plasma is compared with that obtained using the conventional centrifugation based on the enzyme-linked immunosorbent assay. The results reveal that these two blood separation methods have similar detection trends. The proposed filtration chip has the advantages of low cost, short filtration time, and easy operation and thus can be applied to the separation of microparticles, cells, bacteria, and blood.

  8. Large aperture focus stacking with max-gradient flow by anchored rolling filtering.

    PubMed

    Yin, Xuanwu; Wang, Guijin; Li, Wentao; Liao, Qingmin

    2016-07-10

    Focus stacking is a computational technique to extend the depth of field through combining multiple images taken at various focus distances. However, in the large aperture case, there are always defects caused by the large blur scale, which, to the best of our knowledge, has not been well studied. In our work, we propose a max-gradient flow-based method to reduce artifacts and obtain a high-quality all-in-focus image by anchored rolling filtering. First, we define a max-gradient flow to describe the gradient propagation in the stack. The points are divided into trivial and source points with this flow. The source points are extracted as true edge points and are utilized as anchors to refine the depth map and the composited all-in-focus image iteratively. The experiments show that our method can effectively suppress the incorrect depth estimations and give a high-quality all-in-focus image. PMID:27409303

  9. Surface and flow field measurements in a symmetric crossing shock wave/turbulent boundary layer flow

    NASA Technical Reports Server (NTRS)

    Davis, D. O.; Hingst, W. R.

    1992-01-01

    Results of an experimental investigation of a symmetric crossing shock/turbulent boundary layer interaction are presented for a Mach number of 3.44 and deflections angles of 2, 6, 8 and 9 deg. The interaction strengths vary from weak to strong enough to cause a large region of separated flow. Measured quantities include surface static pressure and flowfield Pitot pressures. Pitot profiles in the plane of symmetry through the interaction region are shown for various deflection angles. Oil flow visualization and the results of a trace gas streamline tracking technique are also presented.

  10. Results from Evaluation of Representative ASME AG-1 Section FK Radial Flow Dimple Pleated HEPA Filters Under Elevated Conditions - 12002

    SciTech Connect

    Giffin, Paxton K.; Parsons, Michael S.; Rickert, Jaime G.; Waggoner, Charles A.

    2012-07-01

    The American Society of Mechanical Engineers (ASME) has recently added Section FK establishing requirements for radial flow HEPA filters to the Code on Nuclear Air and Gas Treatment (AG-1). Section FK filters are expected to be a major element in the HEPA filtration systems across the US Department of Energy (DOE) complex. Radial flow filters have been used in Europe for some time, however a limited amount of performance evaluation data exists with respect to these new AG-1 Section FK units. In consultation with a technical working group, the Institute for Clean Energy Technology (ICET) at Mississippi State University (MSU)has evaluated a series of representative AG-1 Section FK dimple pleated radial flow HEPA filters. The effects of elevated relative humidity and temperature conditions on these filters are particularly concerning. Results from the evaluation of Section FK filters under ambient conditions have been presented at the 2011 waste management conference. Additions to the previous test stand to enable high temperature and high humidity testing, a review of the equipment used, the steps taken to characterize the new additions, and the filter test results are presented in this study. Test filters were evaluated at a volumetric flow rate of 56.6 m{sup 3}/min (2000 cfm) and were challenged under ambient conditions with Alumina, Al(OH){sub 3}, until reaching a differential pressure of 1 kPa (4 in. w.c.), at which time the filters were tested, unchallenged with aerosol, at 54 deg. C (130 deg. F) for approximately 1 hour. At the end of that hour water was sprayed near the heat source to maximize vaporization exposing the filter to an elevated relative humidity up to 95%. Collected data include differential pressure, temperature, relative humidity, and volumetric flow rate versus time. (authors)

  11. Cross flow filtration of aqueous radioactive tank wastes

    SciTech Connect

    McCabe, D.J.; Reynolds, B.A.; Todd, T.A.; Wilson, J.H.

    1997-02-01

    The Tank Focus Area (TFA) of the Department of Energy (DOE) Office of Science and Technology addresses remediation of radioactive waste currently stored in underground tanks. Baseline technologies for treatment of tank waste can be categorized into three types of solid liquid separation: (a) removal of radioactive species that have been absorbed or precipitated, (b) pretreatment, and (c) volume reduction of sludge and wash water. Solids formed from precipitation or absorption of radioactive ions require separation from the liquid phase to permit treatment of the liquid as Low Level Waste. This basic process is used for decontamination of tank waste at the Savannah River Site (SRS). Ion exchange of radioactive ions has been proposed for other tank wastes, requiring removal of insoluble solids to prevent bed fouling and downstream contamination. Additionally, volume reduction of washed sludge solids would reduce the tank space required for interim storage of High Level Wastes. The scope of this multi-site task is to evaluate the solid/liquid separations needed to permit treatment of tank wastes to accomplish these goals. Testing has emphasized cross now filtration with metal filters to pretreat tank wastes, due to tolerance of radiation and caustic.

  12. Cross-flow versus counter-current flow packed-bed scrubbers: a mathematical analysis

    SciTech Connect

    Fthenakis, V.M.

    1996-02-01

    Little is known about the mass transfer properties of packing media exposed to a crossflow of gas and liquid, whereas there is abundant information related to counter-current scrubbers. This paper presents a theoretical analysis of mass transfer and hydrodynamics in cross- flow packed bed scrubbers and compares those with information available for counter current towers, so that the first can be evaluated and/or designed based on data derived for the second. Mathematical models of mass transfer in cross-flow and counter- current packed bed scrubbers are presented. From those, one can predict the removal effectiveness of a crossflow scrubber from the number of transfer units (NTU) calculated for a similar counterflow operation; alternatively, when the removal effectiveness in counterflow is known, one can predict the corresponding NTU in crossflow.

  13. Effect of Post-Reconstruction Gaussian Filtering on Image Quality and Myocardial Blood Flow Measurement with N-13 Ammonia PET

    PubMed Central

    Kim, Hyeon Sik; Cho, Sang-Geon; Kim, Ju Han; Kwon, Seong Young; Lee, Byeong-il; Bom, Hee-Seung

    2014-01-01

    Objective(s): In order to evaluate the effect of post-reconstruction Gaussian filtering on image quality and myocardial blood flow (MBF) measurement by dynamic N-13 ammonia positron emission tomography (PET), we compared various reconstruction and filtering methods with image characteristics. Methods: Dynamic PET images of three patients with coronary artery disease (male-female ratio of 2:1; age: 57, 53, and 76 years) were reconstructed, using filtered back projection (FBP) and ordered subset expectation maximization (OSEM) methods. OSEM reconstruction consisted of OSEM_2I, OSEM_4I, and OSEM_6I with 2, 4, and 6 iterations, respectively. The images, reconstructed and filtered by Gaussian filters of 5, 10, and 15 mm, were obtained, as well as non-filtered images. Visual analysis of image quality (IQ) was performed using a 3-grade scoring system by 2 independent readers, blinded to the reconstruction and filtering methods of stress images. Then, signal-to-noise ratio (SNR) was calculated by noise and contrast recovery (CR). Stress and rest MBF and coronary flow reserve (CFR) were obtained for each method. IQ scores, stress and rest MBF, and CFR were compared between the methods, using Chi-square and Kruskal-Wallis tests. Results: In the visual analysis, IQ was significantly higher by 10 mm Gaussian filtering, compared to other sizes of filter (P<0.001 for both readers). However, no significant difference of IQ was found between FBP and various numbers of iteration in OSEM (P=0.923 and 0.855 for readers 1 and 2, respectively). SNR was significantly higher in 10 mm Gaussian filter. There was a significant difference in stress and rest MBF between several vascular territories. However CFR was not significantly different according to various filtering methods. Conclusion: Post-reconstruction Gaussian filtering with a filter size of 10 mm significantly enhances the IQ of N-13 ammonia PET-CT, without changing the results of CFR calculation. PMID:27408866

  14. Define and Quantify the Physics of Air Flow, Pressure Drop and Aerosol Collection in Nuclear Grade HEPA Filters

    SciTech Connect

    Moore, Murray E.

    2015-02-23

    Objective: Develop a set of peer-review and verified analytical methods to adjust HEPA filter performance to different flow rates, temperatures and altitudes. Experimental testing will measure HEPA filter flow rate, pressure drop and efficiency to verify the analytical approach. Nuclear facilities utilize HEPA (High Efficiency Particulate Air) filters to purify air flow for workspace ventilation. However, the ASME AG-1 technical standard (Code on Nuclear Air and Gas Treatment) does not adequately describe air flow measurement units for HEPA filter systems. Specifically, the AG-1 standard does not differentiate between volumetric air flow in ACFM (actual cubic feet per minute)compared to mass flow measured in SCFM (standard cubic feet per minute). More importantly, the AG-1 standard has an overall deficiency for using HEPA filter devices at different air flow rates, temperatures, and altitudes. Technical Approach: The collection efficiency and pressure drops of 18 different HEPA filters will be measured over a range of flow rates, temperatures and altitudes. The experimental results will be compared to analytical scoping calculations. Three manufacturers have allocated six HEPA filters each for this effort. The 18 filters will be tested at two different flow rates, two different temperatures and two different altitudes. The 36 total tests will be conducted at two different facilities: the ATI Test facilities (Baltimore MD) and the Los Alamos National Laboratory (Los Alamos NM). The Radiation Protection RP-SVS group at Los Alamos has an aerosol wind tunnel that was originally designed to evaluate small air samplers. In 2010, modifications were started to convert the wind tunnel for HEPA filter testing. (Extensive changes were necessary for the required aerosol generators, HEPA test fixtures, temperature control devices and measurement capabilities.) To this date, none of these modification activities have been funded through a specific DOE or NNSA program. This is

  15. Pitched and Yawed Circular Jets in Cross-Flow

    NASA Technical Reports Server (NTRS)

    Milanovic, Ivana M.; Zaman, K. B. M. Q.; Reddy, D. R. (Technical Monitor)

    2002-01-01

    Results from an experimental investigation of flow field generated by pitched and yawed jets discharging from a flat plate into a cross-flow are presented. The circular jet was pitched at alpha = 20 degrees and 45 degrees and yawed between beta = 0 degrees and 90 degrees in increments of 15 degrees. The measurements were performed with two X-wires providing all three components of velocity and turbulence intensity. These data were obtained at downstream locations of x = 3, 5, 10 and 20, where the distance x normalized by the jet diameter, is measured from the center of the orifice. Data for all configurations were acquired at a momentum-flux ratio J = 8. Additionally, for selected angles and locations, surveys were conducted for J = 1.5, 4, and 20. As expected, the jet penetration is found to be higher at larger alpha. With increasing beta the jet spreads more. The rate of reduction of peak streamwise vorticity, with the downstream distance is significantly lessened at higher alpha but is found to be practically independent of alpha. Thus, at the farthest measurement station x = 20, omega(sub xmax) is about five times larger for beta = 0 degrees compared to the levels at beta = 0 degrees. Streamwise velocity within the jet-vortex structure is found to depend on the parameter J. At J = 1.5 and 4, 'wake-like' velocity profiles are observed. In comparison, a 'jet-like' overshoot is present at higher J.

  16. Flow interactions of finite-span synthetic jets and a cross flow

    NASA Astrophysics Data System (ADS)

    Vasile, Joseph D.

    The interaction of a finite-span synthetic jet with a cross-flow over a swept-back finite wing was studied experimentally at a Reynolds number of 100,000 and at multiple angles of attack. The focus of the work was to explore the interaction of finite span synthetic jets with a locally attached or separated flow field in the vicinity of the synthetic jet orifice. The effect of blowing ratio and aspect ratio of the jet orifice was discussed in detail. As was shown in previous work for an unswept finite configuration, the time-averaged velocity field exhibits secondary streamwise flow structures that evolve due to the finite span of the synthetic jet orifice. Furthermore, these structures depend upon actuation level of the jet, as well as orifice geometry. Phase-averaged measurements over the swept-back finite configuration showed that in the presence of sweep the flow becomes highly three-dimensional almost immediately downstream of the synthetic jet orifice. It was demonstrated that the baseline flow field that develops over a swept-back configuration (dependent on angle of attack), which is characterized by spanwise and streamwise vorticity components, is responsible for the immediate breakdown of the coherent structures that are introduced by the synthetic jet orifice, and for the formation of the secondary flow structures that were seen in the time-averaged flow field. Furthermore, the effect of jet placement along the span of the wing was studied. A finite-span synthetic jet was placed near the tip of a finite sweptback wing. The focus of that part of the work was to explore the interaction of the synthetic jet with a spatially non-uniform velocity field (due to the presence of a tip vortex), especially the formation and advection of flow structures in the vicinity of the synthetic jet. As was shown, the time-averaged velocity field exhibited streamwise flow structures downstream of the jet. The tip vortex was found to influence the development of the flow

  17. Coupling of stochastic moment equations and Ensemble Kalman Filter for groundwater flow data assimilation (Invited)

    NASA Astrophysics Data System (ADS)

    Guadagnini, A.; Panzeri, M.; Riva, M.; Neuman, S. P.

    2013-12-01

    We embed stochastic groundwater flow moment equations (MEs) in the Ensemble Kalman Filter (EnKF) in a way that obviates the need for Monte Carlo (MC) simulation. The MEs yield approximate conditional ensemble means and covariances of hydraulic heads and fluxes in randomly heterogeneous media. Embedding these in EnKF allows updating of conductivity and head predictors as new data become available without the need for MC. The approach is well suited for cases in which real-time measurements allow sequential (as opposed to simultaneous) updating of flow parameters. We discuss and compare the accuracies and computational efficiencies of our newly proposed ME-based EnKF approach and the traditional MC-based EnKF approach for the case of a pumping well in a two-dimensional randomly heterogeneous aquifer. We analyze a number of settings and investigate the impact on parameters estimates of (a) the number of head measurements assimilated, (b) the error variance associated with head and log conductivity measurements and (c) the initial hydraulic head field. We demonstrate the computational feasibility and accuracy of our methodology and show that hydraulic conductivity estimates are more sensitive to early than to later head values, improving with increased assimilation frequency at early time. Our approach mitigates issues of filter inbreeding and spurious covariances often plaguing standard EnKF.

  18. Anaerobic treatment of cassava starch extraction wastewater using a horizontal flow filter with bamboo as support.

    PubMed

    Colin, X; Farinet, J-L; Rojas, O; Alazard, D

    2007-05-01

    Small-scale sour starch agroindustry in Colombia suffer from absence of water treatment. Although starch processing plants produce diluted wastewater, it is a source of pollution and cause environmental problems to the nearby rural population. A laboratory scale anaerobic horizontal flow filter packed with bamboo pieces was evaluated for the treatment of cassava starch extraction wastewater. The wastewater used in the experimentation was the draining water of the starch sedimentation basin. The reactor was operated for 6 months. It was inoculated with a semi-granular sludge from an anaerobic UASB reactor of a slaughterhouse. Maximum organic loading rate (OLR) applied was 11.8g COD/L d without dilution of the wastewater. At steady state and maximum OLR applied, 87% of the COD was removed and a gas productivity of 3.7L/L d was achieved. The average biogas yield was 0.36L/g COD removed. Methane content in the biogas was in the range of 69-81%. The total suspended solids (TSS) removed were 67%. The relative high lactic acid content did not negatively influence the performance of the reactor. No perturbation due to cyanide (3-5mg/L) was observed during the reactor operation. The results obtained indicated that the anaerobic horizontal flow filter could be used efficiently for the treatment of wastewater from Colombian starch processing small-scale agroindustry.

  19. Anaerobic treatment of cassava starch extraction wastewater using a horizontal flow filter with bamboo as support.

    PubMed

    Colin, X; Farinet, J-L; Rojas, O; Alazard, D

    2007-05-01

    Small-scale sour starch agroindustry in Colombia suffer from absence of water treatment. Although starch processing plants produce diluted wastewater, it is a source of pollution and cause environmental problems to the nearby rural population. A laboratory scale anaerobic horizontal flow filter packed with bamboo pieces was evaluated for the treatment of cassava starch extraction wastewater. The wastewater used in the experimentation was the draining water of the starch sedimentation basin. The reactor was operated for 6 months. It was inoculated with a semi-granular sludge from an anaerobic UASB reactor of a slaughterhouse. Maximum organic loading rate (OLR) applied was 11.8g COD/L d without dilution of the wastewater. At steady state and maximum OLR applied, 87% of the COD was removed and a gas productivity of 3.7L/L d was achieved. The average biogas yield was 0.36L/g COD removed. Methane content in the biogas was in the range of 69-81%. The total suspended solids (TSS) removed were 67%. The relative high lactic acid content did not negatively influence the performance of the reactor. No perturbation due to cyanide (3-5mg/L) was observed during the reactor operation. The results obtained indicated that the anaerobic horizontal flow filter could be used efficiently for the treatment of wastewater from Colombian starch processing small-scale agroindustry. PMID:16973355

  20. Loki--A Lava Lake in Rarefied Circumplanetary Cross Flow

    NASA Astrophysics Data System (ADS)

    Walker, Andrew C.; Goldstein, David B.; Varghese, Philip L.; Trafton, Laurence M.; Moore, Chris H.

    2011-05-01

    The interaction between Io's largest hot spot, Loki, and Io's circumplanetary winds is simulated using the direct simulation Monte Carlo (DSMC) method. Our three-dimensional simulation models the rarefied pressure-driven boundary layer flow over a ``hot'' disk in the presence of a weak gravitational field. The pressure gradient which forces winds away from the subsolar point toward the nightside is caused by the variation in insolation over the surface. The rarefaction varies strongly with time of day due to the exponential dependence of the vapor pressure on the surrounding surface frost temperature (KnHS~1×10-4 to 0.5 where KnHS = λ/R, λ is the mean free path, and R is Loki's effective radius). The spread of heat from the hot spot, the equilibration of pressure over the hot spot, and separation of the boundary layer are examined. The spread of heat away from the hot spot is approximately controlled by δ = tRADU/R (tRAD is the radiation time scale and U is the mean wind speed). For cross flow speed considered here, δ~0.5 and therefore the gas warmed by the hot spot cools by e-1~0.5R downstream of the hot spot edge. For the cases without plasma heating, the boundary layer flow separates near the hot spot because the spot creates a significant adverse pressure gradient. Despite the near surface pressure over the hot spot being lower than over surrounding regions, the increased scale height due to the 332 K surface temperature results in higher pressures above the hot spot than the surrounding sublimation atmosphere at high altitudes (>10 km). When plasma heating from above is included the atmosphere is significantly inflated leading to a higher pressure gradient at all altitudes and therefore higher flow speeds. The elevated pressure at high altitudes also decreases the relative size of the adverse pressure gradient created by the hot spot; therefore the boundary layer remains attached. The pressure over the hot spot does not equilibrate with the surrounding

  1. Disk filter

    DOEpatents

    Bergman, W.

    1985-01-09

    An electric disk filter provides a high efficiency at high temperature. A hollow outer filter of fibrous stainless steel forms the ground electrode. A refractory filter material is placed between the outer electrode and the inner electrically isolated high voltage electrode. Air flows through the outer filter surfaces through the electrified refractory filter media and between the high voltage electrodes and is removed from a space in the high voltage electrode.

  2. Disk filter

    DOEpatents

    Bergman, Werner

    1986-01-01

    An electric disk filter provides a high efficiency at high temperature. A hollow outer filter of fibrous stainless steel forms the ground electrode. A refractory filter material is placed between the outer electrode and the inner electrically isolated high voltage electrode. Air flows through the outer filter surfaces through the electrified refractory filter media and between the high voltage electrodes and is removed from a space in the high voltage electrode.

  3. Effect of filter media size, mass flow rate and filtration stage number in a moving-bed granular filter on the yield and properties of bio-oil from fast pyrolysis of biomass.

    PubMed

    Paenpong, Chaturong; Inthidech, Sudsakorn; Pattiya, Adisak

    2013-07-01

    Fast pyrolysis of cassava rhizome was performed in a bench-scale fluidised-bed reactor unit incorporated with a cross-flow moving-bed granular filter. The objective of this research was to examine several process parameters including the granular size (425-1160 μm) and mass flow rate (0-12 g/min) as well as the number of the filtration stages (1-2 stages) on yields and properties of bio-oil. The results showed that the bio-oil yield decreased from 57.7 wt.% to 42.0-49.2 wt.% when increasing the filter media size, the mass flow rate and the filtration stage number. The effect of the process parameters on various properties of bio-oil is thoroughly discussed. In general, the bio-oil quality in terms of the solids content, ash content, initial viscosity, viscosity change and ageing rate could be enhanced by the hot vapour granular filtration. Therefore, bio-oil of high stability could be produced by the pyrolysis reactor configuration designed in this work.

  4. Impact of ENSO on Western Pacific Cross-equatorial Flows

    NASA Astrophysics Data System (ADS)

    Zhou, Y.; Kim, H.

    2015-12-01

    The Western Pacific cross-equatorial flows (CEFs) show evident interannual variability in boreal summer. Results from Principle Component Analysis indicate that El Niño/Southern Oscillation modulates the interannual variability of Western Pacific CEFs. Both Matsuno-Gill mechanism and Lindzen-Nigam mechanism are introduced and applied in order to better explain the development of CEFs. Using the Mixed Layer Model by Stevens (2002) and methods stated by Back and Bretherton (2009), the low-level CEFs are decomposed into two pressure gradient contributions: free-atmosphere and boundary layer; and further found mainly contributed by the latter one. The intensity of boundary layer pressure gradient is highly coincide with the distribution of sea surface temperature (SST) gradient on Western Pacific, which is intensified by El Niño in boreal summer. These results show that the Lindzen-Nigam mechanism plays a major role on CEFs' interannual change. An atmosphere general circulation model is included to support the influence of SST forcing on low-level CEFs. North American Multi-Model Ensemble is further adopted to understand the seasonal predictability of CEFs.

  5. Numerical calculation of the transient behaviour of two pure cross-flow heat exchangers coupled by a circulating flow stream

    NASA Astrophysics Data System (ADS)

    Na Ranong, Chakkrit; Hapke, Jobst; Roetzel, Wilfried

    2010-11-01

    The transient thermal behaviour of a heat shifting system consisting of two pure cross-flow heat exchangers coupled by a circulating flow stream is studied theoretically. A suitable mathematical description of the system is based on the energy balance equation for general flow processes yielding a system of coupled hyperbolic partial differential equations in two dimensions. System responses to perturbations of inlet temperatures and mass flow rates are numerically calculated with an explicit finite difference method. A criterion for the generation of computational grids minimising effects of numerical dispersion and dissipation is applied to the system of coupled pure cross-flow heat exchangers which has not been considered up to now. Due to its internal circulation the coupled system shows a different behaviour compared to single cross-flow heat exchangers like inverse response and oscillatory behaviour to non-oscillating input signals.

  6. Temporal filtering of event-related fMRI data using cross-validation.

    PubMed

    Ngan, S C; LaConte, S M; Hu, X

    2000-06-01

    To circumvent the problem of low signal-to-noise ratio (SNR) in event-related fMRI data, the fMRI experiment is typically designed to consist of repeated presentations of the stimulus and measurements of the response, allowing for subsequent averaging of the resulting data. Due to factors such as time limitation, subject motion, habituation, and fatigue, practical constraints on the number of repetitions exist. Thus, filtering is commonly applied to further improve the SNR of the averaged data. Here, a time-varying filter based on theoretical work by Nowak is employed. This filter operates under the stationary wavelet transform framework and is demonstrated to lead to good estimates of the true signals in simulated data. The utility of the filter is also shown using experimental data obtained with a visual-motor paradigm.

  7. Data Assimilation for Vadose Zone Flow Modeling Using the Ensemble Kalman Filter

    NASA Astrophysics Data System (ADS)

    Zhang, Y.; Schaap, M. G.; Zha, Y.; Xue, L.

    2015-12-01

    The natural system is open and complex and the hydraulic parameters needed for describing flow and transport in the vadose zone are often poorly known, making it prone to multiple interpretations, mathematical descriptions and uncertainty. Quite often a reasonable "handle" on a sites flow characteristics can be gained only through direct observation of the flow processes itself, determination of the spatial- and probability distributions of material properties combined with computationally expensive inversions of the Richards equation. In groundwater systems, the ensemble Kalman filter (EnKF) has proven to be an effective alternative to model inversions by assimilating observations directly into an ensemble of groundwater models from which time and/or space-variable variable probabilistic quantities of the flow process can be derived. Application of EnKF to Richards equation-type unsaturated flow problems, however, is more challenging than in groundwater systems because the relation of state and model parameters is strongly nonlinear. In addition, the type of functional dependence of moisture content and hydraulic conductivity on matric potential leads to high-dimensional (in the parameter space) problems even under conditions where closed-form expressions of these models such as van Genuchten-Mualem formulations are used. In this study, we updated soil water retention parameters and hydraulic conductivity together and used Restart EnKF, which rerun the nonlinear model from the initial time to obtain the updated state variables, in synthetic cases to explore the factors that may influence estimation results, including the initial estimate, the ensemble size, the observation error, and the assimilation interval. We embedded the EnKF into the Bayesian model averaging framework to enhance the model reliability and reduce predictive uncertainties. This approach is evaluated from a 15 m deep semi-arid highly heterogeneous and anisotropic vadose zone site at the

  8. Baleen wear reveals intraoral water flow patterns of mysticete filter feeding.

    PubMed

    Werth, Alexander J; Straley, Janice M; Shadwick, Robert E

    2016-04-01

    A survey of macroscopic and microscopic wear patterns in the baleen of eight whale species (Cetacea: Mysticeti) discloses structural, functional, and life history properties of this neomorphic keratinous tissue, including evidence of intraoral water flow patterns involved in filter feeding. All baleen demonstrates wear, particularly on its medial and ventral edges, as flat outer layers of cortical keratin erode to reveal horn tubes, also of keratin, which emerge as hair-like fringes. This study quantified five additional categories of specific wear: pitting of plates, scratching of plates, scuffing of fringes, shortening of fringes, and reorientation of fringes (including fringes directed between plates to the exterior of the mouth). Blue whale baleen showed the most pitting and sei whale baleen the most scratching; gray whale baleen had the most fringe wear. The location of worn baleen within the mouth suggests that direct contact with the tongue is not responsible for most wear, and that flowing water as well as abrasive prey or sediment carried by the flowing water likely causes pitting and scratching of plates as well as fringe fraying, scuffing, shortening, and reorientation. Baleen also has elevated vertical and horizontal ridges that are unrelated to wear; these are probably related to growth and may allow for age determination. PMID:26825852

  9. Baleen wear reveals intraoral water flow patterns of mysticete filter feeding.

    PubMed

    Werth, Alexander J; Straley, Janice M; Shadwick, Robert E

    2016-04-01

    A survey of macroscopic and microscopic wear patterns in the baleen of eight whale species (Cetacea: Mysticeti) discloses structural, functional, and life history properties of this neomorphic keratinous tissue, including evidence of intraoral water flow patterns involved in filter feeding. All baleen demonstrates wear, particularly on its medial and ventral edges, as flat outer layers of cortical keratin erode to reveal horn tubes, also of keratin, which emerge as hair-like fringes. This study quantified five additional categories of specific wear: pitting of plates, scratching of plates, scuffing of fringes, shortening of fringes, and reorientation of fringes (including fringes directed between plates to the exterior of the mouth). Blue whale baleen showed the most pitting and sei whale baleen the most scratching; gray whale baleen had the most fringe wear. The location of worn baleen within the mouth suggests that direct contact with the tongue is not responsible for most wear, and that flowing water as well as abrasive prey or sediment carried by the flowing water likely causes pitting and scratching of plates as well as fringe fraying, scuffing, shortening, and reorientation. Baleen also has elevated vertical and horizontal ridges that are unrelated to wear; these are probably related to growth and may allow for age determination.

  10. Viscous Flow through Pipes of Various Cross-Sections

    ERIC Educational Resources Information Center

    Lekner, John

    2007-01-01

    An interesting variety of pipe cross-sectional shapes can be generated, for which the Navier-Stokes equations can be solved exactly. The simplest cases include the known solutions for elliptical and equilateral triangle cross-sections. Students can find pipe cross-sections from solutions of Laplace's equation in two dimensions, and then plot the…

  11. Design of jitter compensation algorithm for robot vision based on optical flow and Kalman filter.

    PubMed

    Wang, B R; Jin, Y L; Shao, D L; Xu, Y

    2014-01-01

    Image jitters occur in the video of the autonomous robot moving on bricks road, which will reduce robot operation precision based on vision. In order to compensate the image jitters, the affine transformation kinematics were established for obtaining the six image motion parameters. The feature point pair detecting method was designed based on Eigen-value of the feature windows gradient matrix, and the motion parameters equation was solved using the least square method and the matching point pairs got based on the optical flow. The condition number of coefficient matrix was proposed to quantificationally analyse the effect of matching errors on parameters solving errors. Kalman filter was adopted to smooth image motion parameters. Computing cases show that more point pairs are beneficial for getting more precise motion parameters. The integrated jitters compensation software was developed with feature points detecting in subwindow. And practical experiments were conducted on two mobile robots. Results show that the compensation costing time is less than frame sample time and Kalman filter is valid for robot vision jitters compensation. PMID:24600320

  12. Design of jitter compensation algorithm for robot vision based on optical flow and Kalman filter.

    PubMed

    Wang, B R; Jin, Y L; Shao, D L; Xu, Y

    2014-01-01

    Image jitters occur in the video of the autonomous robot moving on bricks road, which will reduce robot operation precision based on vision. In order to compensate the image jitters, the affine transformation kinematics were established for obtaining the six image motion parameters. The feature point pair detecting method was designed based on Eigen-value of the feature windows gradient matrix, and the motion parameters equation was solved using the least square method and the matching point pairs got based on the optical flow. The condition number of coefficient matrix was proposed to quantificationally analyse the effect of matching errors on parameters solving errors. Kalman filter was adopted to smooth image motion parameters. Computing cases show that more point pairs are beneficial for getting more precise motion parameters. The integrated jitters compensation software was developed with feature points detecting in subwindow. And practical experiments were conducted on two mobile robots. Results show that the compensation costing time is less than frame sample time and Kalman filter is valid for robot vision jitters compensation.

  13. Design of Jitter Compensation Algorithm for Robot Vision Based on Optical Flow and Kalman Filter

    PubMed Central

    Wang, B. R.; Jin, Y. L.; Shao, D. L.; Xu, Y.

    2014-01-01

    Image jitters occur in the video of the autonomous robot moving on bricks road, which will reduce robot operation precision based on vision. In order to compensate the image jitters, the affine transformation kinematics were established for obtaining the six image motion parameters. The feature point pair detecting method was designed based on Eigen-value of the feature windows gradient matrix, and the motion parameters equation was solved using the least square method and the matching point pairs got based on the optical flow. The condition number of coefficient matrix was proposed to quantificationally analyse the effect of matching errors on parameters solving errors. Kalman filter was adopted to smooth image motion parameters. Computing cases show that more point pairs are beneficial for getting more precise motion parameters. The integrated jitters compensation software was developed with feature points detecting in subwindow. And practical experiments were conducted on two mobile robots. Results show that the compensation costing time is less than frame sample time and Kalman filter is valid for robot vision jitters compensation. PMID:24600320

  14. Illustration of cross flow of polystyrene melts through a coathanger die

    NASA Astrophysics Data System (ADS)

    Schöppner, V.; Henke, B.

    2015-05-01

    To design an optimal coathanger die with a uniform flow rate distribution and low pressure drop, it is essential to understand the flow conditions in the die. This is important because the quality of the product is influenced by the flow velocity and the flow rate distribution. In extrusion dies, cross flows also occur in addition to the main flow, which flow perpendicular to the main flow. This results in pressure gradients in the extrusion direction, which have an influence on flow distribution and pressure drop in the die. In recent decades, quantitative representation and analysis of physical flow processes have made considerable progress in predicting the weather, developing drive technologies and designing aircraft using simulation methods and lab trials. Using the flow-line method, the flow is analyzed in flat film extrusion dies with a rectangular cross-section, in particular cross flows. The simplest method to visualize the flow is based on the measurement of obstacle orientation in the flow field by adding individual particles. A near-surface flow field can be visualized by using wool or textile yarns. By sticking thin, frayed at the ends of strands of wool surface that is to be examined cross flows, near-wall profiles of the flow and vortex and separation regions can be visualized. A further possibility is to add glass fibers and analyze the fiber orientation by microscopy and x-ray analysis. In this paper the influence of process parameters (e.g. melt temperatures and throughput) on cross flow and fiber orientation is described.

  15. Fuzzy State Transition and Kalman Filter Applied in Short-Term Traffic Flow Forecasting

    PubMed Central

    Ming-jun, Deng; Shi-ru, Qu

    2015-01-01

    Traffic flow is widely recognized as an important parameter for road traffic state forecasting. Fuzzy state transform and Kalman filter (KF) have been applied in this field separately. But the studies show that the former method has good performance on the trend forecasting of traffic state variation but always involves several numerical errors. The latter model is good at numerical forecasting but is deficient in the expression of time hysteretically. This paper proposed an approach that combining fuzzy state transform and KF forecasting model. In considering the advantage of the two models, a weight combination model is proposed. The minimum of the sum forecasting error squared is regarded as a goal in optimizing the combined weight dynamically. Real detection data are used to test the efficiency. Results indicate that the method has a good performance in terms of short-term traffic forecasting. PMID:26779258

  16. Fuzzy State Transition and Kalman Filter Applied in Short-Term Traffic Flow Forecasting.

    PubMed

    Deng, Ming-jun; Qu, Shi-ru

    2015-01-01

    Traffic flow is widely recognized as an important parameter for road traffic state forecasting. Fuzzy state transform and Kalman filter (KF) have been applied in this field separately. But the studies show that the former method has good performance on the trend forecasting of traffic state variation but always involves several numerical errors. The latter model is good at numerical forecasting but is deficient in the expression of time hysteretically. This paper proposed an approach that combining fuzzy state transform and KF forecasting model. In considering the advantage of the two models, a weight combination model is proposed. The minimum of the sum forecasting error squared is regarded as a goal in optimizing the combined weight dynamically. Real detection data are used to test the efficiency. Results indicate that the method has a good performance in terms of short-term traffic forecasting. PMID:26779258

  17. Fuzzy State Transition and Kalman Filter Applied in Short-Term Traffic Flow Forecasting.

    PubMed

    Deng, Ming-jun; Qu, Shi-ru

    2015-01-01

    Traffic flow is widely recognized as an important parameter for road traffic state forecasting. Fuzzy state transform and Kalman filter (KF) have been applied in this field separately. But the studies show that the former method has good performance on the trend forecasting of traffic state variation but always involves several numerical errors. The latter model is good at numerical forecasting but is deficient in the expression of time hysteretically. This paper proposed an approach that combining fuzzy state transform and KF forecasting model. In considering the advantage of the two models, a weight combination model is proposed. The minimum of the sum forecasting error squared is regarded as a goal in optimizing the combined weight dynamically. Real detection data are used to test the efficiency. Results indicate that the method has a good performance in terms of short-term traffic forecasting.

  18. Real-time groundwater flow modeling with the Ensemble Kalman Filter: Joint estimation of states and parameters and the filter inbreeding problem

    NASA Astrophysics Data System (ADS)

    Hendricks Franssen, H. J.; Kinzelbach, W.

    2008-09-01

    Real-time groundwater flow modeling with filter methods is interesting for dynamical groundwater flow systems, for which measurement data in real-time are available. The Ensemble Kalman Filter (EnKF) approach is used here to update states together with parameters by adopting an augmented state vector approach. The performance of EnKF is investigated in a synthetic study with a two-dimensional transient groundwater flow model where (1) only the recharge rate is spatiotemporally variable, (2) only transmissivity is spatially variable with σlnT2 = 1.0 or (3) with σlnT2 = 2.7, and (4) both recharge rate and transmissivity are uncertain (a combination of (1) and (3)). The performance of EnKF for simultaneous state and parameter estimation in saturated groundwater flow problems is investigated in dependence of the number of stochastic realizations, the updating frequency and updating intensity of log-transmissivity, the amount of measurements in space and time, and the method (iterative versus noniterative EnKF), among others. Satisfactory results were also obtained if both transmissivity and recharge rate were uncertain. However, it was found that filter inbreeding is much more severe if hydraulic heads and transmissivities are jointly updated than if only hydraulic heads are updated. The filter inbreeding problem was investigated in more detail and could be strongly reduced with help of a damping parameter, which limits the intensity of the perturbation of the log-transmissivity field. An additional reduction of filter inbreeding could be achieved by combining two measures: (1) inflating the elements of the predicted state covariance matrix on the basis of a comparison between the model uncertainty and the observed errors at the measurement points and (2) starting the flow simulations with a very large number of realizations and then sampling the desired number of realizations after one simulation time step by minimizing the differences between the local cpdfs (and

  19. Flow topologies and turbulence scales in a jet-in-cross-flow

    DOE PAGESBeta

    Oefelein, Joseph C.; Ruiz, Anthony M.; Lacaze, Guilhem

    2015-04-03

    This study presents a detailed analysis of the flow topologies and turbulence scales in the jet-in-cross-flow experiment of [Su and Mungal JFM 2004]. The analysis is performed using the Large Eddy Simulation (LES) technique with a highly resolved grid and time-step and well controlled boundary conditions. This enables quantitative agreement with the first and second moments of turbulence statistics measured in the experiment. LES is used to perform the analysis since experimental measurements of time-resolved 3D fields are still in their infancy and because sampling periods are generally limited with direct numerical simulation. A major focal point is the comprehensivemore » characterization of the turbulence scales and their evolution. Time-resolved probes are used with long sampling periods to obtain maps of the integral scales, Taylor microscales, and turbulent kinetic energy spectra. Scalar-fluctuation scales are also quantified. In the near-field, coherent structures are clearly identified, both in physical and spectral space. Along the jet centerline, turbulence scales grow according to a classical one-third power law. However, the derived maps of turbulence scales reveal strong inhomogeneities in the flow. From the modeling perspective, these insights are useful to design optimized grids and improve numerical predictions in similar configurations.« less

  20. Flow topologies and turbulence scales in a jet-in-cross-flow

    NASA Astrophysics Data System (ADS)

    Ruiz, A. M.; Lacaze, G.; Oefelein, J. C.

    2015-04-01

    This paper presents a detailed analysis of the flow topologies and turbulence scales in the jet-in-cross-flow experiment of Su and Mungal ["Simultaneous measurements of scalar and velocity field evolution in turbulent crossflowing jets," J. Fluid Mech. 513(1), 1-45 (2004)]. The analysis is performed using the Large Eddy Simulation (LES) technique with a highly resolved grid and time-step and well controlled boundary conditions. This enables quantitative agreement with the first and second moments of turbulence statistics measured in the experiment. LES is used to perform the analysis since experimental measurements of time-resolved 3D fields are still in their infancy and because sampling periods are generally limited with direct numerical simulation. A major focal point is the comprehensive characterization of the turbulence scales and their evolution. Time-resolved probes are used with long sampling periods to obtain maps of the integral scales, Taylor microscales, and turbulent kinetic energy spectra. Scalar-fluctuation scales are also quantified. In the near-field, coherent structures are clearly identified, both in physical and spectral space. Along the jet centerline, turbulence scales grow according to a classical one-third power law. However, the derived maps of turbulence scales reveal strong inhomogeneities in the flow. From the modeling perspective, these insights are useful to design optimized grids and improve numerical predictions in similar configurations.

  1. Flow topologies and turbulence scales in a jet-in-cross-flow

    SciTech Connect

    Oefelein, Joseph C.; Ruiz, Anthony M.; Lacaze, Guilhem

    2015-04-03

    This study presents a detailed analysis of the flow topologies and turbulence scales in the jet-in-cross-flow experiment of [Su and Mungal JFM 2004]. The analysis is performed using the Large Eddy Simulation (LES) technique with a highly resolved grid and time-step and well controlled boundary conditions. This enables quantitative agreement with the first and second moments of turbulence statistics measured in the experiment. LES is used to perform the analysis since experimental measurements of time-resolved 3D fields are still in their infancy and because sampling periods are generally limited with direct numerical simulation. A major focal point is the comprehensive characterization of the turbulence scales and their evolution. Time-resolved probes are used with long sampling periods to obtain maps of the integral scales, Taylor microscales, and turbulent kinetic energy spectra. Scalar-fluctuation scales are also quantified. In the near-field, coherent structures are clearly identified, both in physical and spectral space. Along the jet centerline, turbulence scales grow according to a classical one-third power law. However, the derived maps of turbulence scales reveal strong inhomogeneities in the flow. From the modeling perspective, these insights are useful to design optimized grids and improve numerical predictions in similar configurations.

  2. Cross-flow ultrafiltration of micellar surfactant solutions

    SciTech Connect

    Markels, J.H.; Lynn, S.; Radke, C.J.

    1995-09-01

    A steady-state fouling-resistance and osmotic-pressure model is used to predict flux in the laminar, cross-flow ultrafiltration of micellar cetyl (=hexadecyl)pyridinium chloride (CPC) solutions at 0.01-M NaCl background electrolyte. The model assumes a constant overall hydraulic resistance including the effect of surfactant fouling and native membrane resistance. Measurements of osmotic pressures of CPC solutions at 0.01-M NaCl as a function of surfactant concentration describe the effect of concentration polarization on permeate flux. Two types of asymmetric polyethersulfone membranes are used: 5,000 molecular weight cutoff (MWCO) membranes that allow partial monomer permeation, but quantitatively reject all micelles; 50,000 MWCO membranes that allow some micelle permeation. For the former, the intrinsic rejection coefficient for monomer, measured separately, is sufficient to describe surfactant rejection, without adjustable parameters. Predictions of the volumetric flux of the permeate, including the value of the limiting flux, agree well with the experimental results over the entire range of pressure drop, axial velocity, and bulk surfactant concentration. For the 50,000 MWCO membranes the data are described using a best-fit value of the overall surfactant rejection coefficient. For the first time, unusual behavior is observed experimentally in which the flux levels off with increasing pressure drop across the membrane, only to increase sharply again at higher applied pressure drop. Both effects are in accord with the proposed model. No gel layer need be postulated to explain the flux behavior of either membrane type.

  3. Water Filters

    NASA Technical Reports Server (NTRS)

    1987-01-01

    A compact, lightweight electrolytic water filter generates silver ions in concentrations of 50 to 100 parts per billion in the water flow system. Silver ions serve as effective bactericide/deodorizers. Ray Ward requested and received from NASA a technical information package on the Shuttle filter, and used it as basis for his own initial development, a home use filter.

  4. Experimental study on exciting force by two-phase cross flow

    SciTech Connect

    Nakamura, T.; Fujita, K.; Shiraki, K.; Kanazawa, H.; Sakata, K.

    1982-01-01

    Buffeting forces acting on tube arrays and induced by air-water two-phase cross flow, in the range of bubble flow and slug flow (or froth flow), are experimentally examined. Experimental results are treated by statistical modal analysis for use in design calculation. Based on these results, a hypothesis, especially applicable in the region of slug flow, is proposed to explain the experimental results. 9 refs.

  5. Experimental investigation and CFD analysis on cross flow in the core of PMR200

    SciTech Connect

    Lee, Jeong -Hun; Yoon, Su -Jong; Cho, Hyoung -Kyu; Jae, Moosung; Park, Goon -Cherl

    2015-04-16

    The Prismatic Modular Reactor (PMR) is one of the major Very High Temperature Reactor (VHTR) concepts, which consists of hexagonal prismatic fuel blocks and reflector blocks made of nuclear gradegraphite. However, the shape of the graphite blocks could be easily changed by neutron damage duringthe reactor operation and the shape change can create gaps between the blocks inducing the bypass flow.In the VHTR core, two types of gaps, a vertical gap and a horizontal gap which are called bypass gap and cross gap, respectively, can be formed. The cross gap complicates the flow field in the reactor core by connecting the coolant channel to the bypass gap and it could lead to a loss of effective coolant flow in the fuel blocks. Thus, a cross flow experimental facility was constructed to investigate the cross flow phenomena in the core of the VHTR and a series of experiments were carried out under varying flow rates and gap sizes. The results of the experiments were compared with CFD (Computational Fluid Dynamics) analysis results in order to verify its prediction capability for the cross flow phenomena. Fairly good agreement was seen between experimental results and CFD predictions and the local characteristics of the cross flow was discussed in detail. Based on the calculation results, pressure loss coefficient across the cross gap was evaluated, which is necessary for the thermo-fluid analysis of the VHTR core using a lumped parameter code.

  6. Experimental investigation and CFD analysis on cross flow in the core of PMR200

    DOE PAGESBeta

    Lee, Jeong -Hun; Yoon, Su -Jong; Cho, Hyoung -Kyu; Jae, Moosung; Park, Goon -Cherl

    2015-04-16

    The Prismatic Modular Reactor (PMR) is one of the major Very High Temperature Reactor (VHTR) concepts, which consists of hexagonal prismatic fuel blocks and reflector blocks made of nuclear gradegraphite. However, the shape of the graphite blocks could be easily changed by neutron damage duringthe reactor operation and the shape change can create gaps between the blocks inducing the bypass flow.In the VHTR core, two types of gaps, a vertical gap and a horizontal gap which are called bypass gap and cross gap, respectively, can be formed. The cross gap complicates the flow field in the reactor core by connectingmore » the coolant channel to the bypass gap and it could lead to a loss of effective coolant flow in the fuel blocks. Thus, a cross flow experimental facility was constructed to investigate the cross flow phenomena in the core of the VHTR and a series of experiments were carried out under varying flow rates and gap sizes. The results of the experiments were compared with CFD (Computational Fluid Dynamics) analysis results in order to verify its prediction capability for the cross flow phenomena. Fairly good agreement was seen between experimental results and CFD predictions and the local characteristics of the cross flow was discussed in detail. Based on the calculation results, pressure loss coefficient across the cross gap was evaluated, which is necessary for the thermo-fluid analysis of the VHTR core using a lumped parameter code.« less

  7. Nonstationary Gas Flow in Thin Pipes of Variable Cross Section

    NASA Technical Reports Server (NTRS)

    Guderley, G.

    1948-01-01

    Characteristic methods for nonstationary flows have been published only for the special case of the isentropic flow up until the present, althought they are applicable in various places to more difficult questions too. This report derives the characteristic method for the flows which depend only on the position coordinates and time. At the same time the treatment of compression shocks is shown.

  8. Application of Filtered Spherical Harmonics Radiation Transport to High-Speed Reactive Flow

    NASA Astrophysics Data System (ADS)

    Houim, Ryan; Oran, Elaine

    2015-11-01

    Radiative heat transfer is an important, but often neglected, process in high-speed reacting and multiphase flow applications. Some scenarios, such as dust explosions in coal mines, can have regions that are nearly transparent and other regions with high dust concentration that are optically thick. Most approximations to the radiative transfer equation (RTE) are not valid in both limits simultaneously. Issues also arise when solving approximations to the RTE that can often require the solution of elliptic equations. Many compressible hydrodynamic codes use explicit time-marching and block-structured adaptive-mesh-refinement algorithms. Adapting these codes to solve elliptic equations is not always straightforward. Recently, filtered spherical harmonics (FPN) approximations to the RTE have been developed. The FPN equations are hyperbolic and, as a result, can be solved using algorithms that are similar Godunov's method for compressible fluid flow. The FPN model is also valid in optically thick and thin situations provided that the order, N, is high enough. We show that the FPN equations are a promising alternative to traditional RTE approximations. Challenging test cases that involve both free-streaming and optically thick regions will be presented.

  9. Simplified groundwater flow modeling: an application of Kalman filter based identification

    SciTech Connect

    Pimentel, K.D.; Candy, J.V.; Azevedo, S.G.; Doerr, T.A.

    1980-05-01

    The need exists for methods to simplify groundwater contaminant transport models. Reduced-order models are needed in risk assessments for licensing and regulating long-term nuclear waste repositories. Such models will be used in Monte Carlo simulations to generate probabilities of nuclear waste migration in aquifers at candidate repository sites in the United States. In this feasibility study we focused on groundwater flow rather than contaminant transport because the flow problem is more simple. A pump-drawdown test is modeled with a reduced-order set of ordinary differential equations obtained by differencing the partial differential equation. We determined the accuracy of the reduced model by comparing it with the analytic solution for the drawdown test. We established an accuracy requirement of 2% error at the single observation well and found that a model with only 21 states satisfied that criterion. That model was used in an extended Kalman filter with synthesized measurement data from one observation well to identify transmissivity within 1% error and storage coefficient within 10% error. We used several statistical tests to assess the performance of the estimator/identifier and found it to be satisfactory for this application.

  10. Cross-flow vortex structure and transition measurements using multi-element hot films

    NASA Technical Reports Server (NTRS)

    Agarwal, Naval K.; Mangalam, Siva M.; Maddalon, Dal V.; Collier, Fayette S., Jr.

    1991-01-01

    An experiment on a 45-degree swept wing was conducted to study three-dimensional boundary-layer characteristics using surface-mounted, micro-thin, multi-element hot-film sensors. Cross-flow vortex structure and boundary-layer transition were measured from the simultaneously acquired signals of the hot films. Spanwise variation of the root-mean-square (RMS) hot-film signal show a local minima and maxima. The distance between two minima corresponds to the stationary cross-flow vortex wavelength and agrees with naphthalene flow-visualization results. The chordwise and spanwise variation of amplified traveling (nonstationary) cross-flow disturbance characteristics were measured as Reynolds number was varied. The frequency of the most amplified cross-flow disturbances agrees with linear stability theory.

  11. Calculation of linearized supersonic flow over slender cones of arbitrary cross section

    NASA Technical Reports Server (NTRS)

    Mascitti, V. R.

    1972-01-01

    Supersonic linearized conical-flow theory is used to determine the flow over slender pointed cones having horizontal and vertical planes of symmetry. The geometry of the cone cross sections and surface velocities are expanded in Fourier series. The symmetry condition permits the uncoupling of lifting and nonlifting solutions. The present method reduces to Ward's theory for flow over a cone of elliptic cross section. Results are also presented for other shapes. Results by this method diverge for cross-sectional shapes where the maximum thickness is large compared with the minimum thickness. However, even for these slender-body shapes, lower order solutions are good approximations to the complete solution.

  12. Measurements of Neutron Capture Cross-Section for Tantalum at the Neutron Filtered Beams

    NASA Astrophysics Data System (ADS)

    Gritzay, Olena; Libman, Volodymyr

    2009-08-01

    The neutron capture cross sections of tantalum have been measured for the neutron energies 2 and 59 keV using the WWR-M Kyiv Research Reactor (KRR) of the Institute for Nuclear Research of the National Academy of Science of Ukraine. The cross sections of 181Ta (n, γ) 182Ta reaction were obtained by the activation method using a gamma-spectrometer with Ge(Li)-detector. The obtained neutron capture cross sections were compared with the known experimental data from database EXFOR/CSISRS and the ENDF libraries.

  13. An analysis of pressure driven cross-flow through a long slot connecting two parallel channels

    SciTech Connect

    Shadday, M.A. Jr.

    1992-12-31

    Cross-flow between two parallel channels that were connected by a long narrow slot has been measured. The data was presented primarily in terms of transverse resistance coefficients. This data has been analyzed with momentum balances applied to both the axial and transverse components of the slot flow. The importance of wall friction to the slot flow and the necessity of calculating the axial component of the slot flow is demonstrated.

  14. Assessing the performance of the ensemble Kalman filter for subsurface flow data integration under variogram uncertainty

    NASA Astrophysics Data System (ADS)

    Jafarpour, B.; Tarrahi, Mohammadali

    2011-05-01

    The ensemble Kalman filter (EnKF) has recently been proposed as a promising parameter estimation approach for constraining the description of rock flow properties, such as permeability and porosity, to reproduce flow measurements that are modeled as nonlinear functions of these properties. One of the key factors that strongly affect the performance of the EnKF is the quality or representativeness of the prior ensemble of property fields used to initialize the EnKF assimilation procedure. The initial ensemble is commonly constructed by assuming a known geological continuity model such as a variogram. However, geologic continuity models are derived from incomplete information and imperfect modeling assumptions, which can introduce a significant level of uncertainty into the produced models. Neglecting this important source of uncertainty can lead to systematic errors and questionable estimation results. In this paper, we investigate the performance of the EnKF under varying levels of uncertainty in the variogram model parameters. We first attempt to directly estimate variogram model parameters from flow data and show that the complex and nonunique relation they have with the flow data provides little sensitivity for an effective inversion with the EnKF. We then assess the performance of the EnKF for estimation of permeability values under uncertain and incorrect initial variogram parameters and show that any bias in specifying variogram parameters tends to persist throughout the EnKF analysis even though locally reasonable permeability updates may be obtained near observation points. More importantly, we show that when variogram parameters are specified probabilistically to account for the full range of structural variability in the initial permeability ensemble, the EnKF update results are quite promising. The results suggest that under uncertain geologic continuity, the EnKF tends to perform better if a very diverse set of property fields is used to form the

  15. Averaged indicators of secondary flow in repeated acoustic Doppler current profiler crossings of bends

    USGS Publications Warehouse

    Dinehart, R.L.; Burau, J.R.

    2005-01-01

    [1] Cross-stream velocity was measured in a large river bend at high spatial resolution over three separate survey episodes. A suite of methods for resolving cross-stream velocity distributions was tested on data collected using acoustic Doppler current profilers (ADCP) in the sand-bedded Sacramento River, California. The bend was surveyed with repeated ADCP crossings at eight cross sections during a rising limb of high discharge in February 2004 and twice on recession in March 2004. By translating and interpolating repeated ADCP crossings to planar grids, velocity ensembles at similar positions along irregular boat paths could be averaged. The averaging minimized turbulent fluctuations in streamwise velocities over 1 m/s, enabling the resolution of weaker cross-stream velocities (???15-30 cm/s). Secondary-flow influence on suspended sediment was inferred from a lateral region of acoustic backscatter intensity aligned with outward flow over the point bar. A near-bed decrease in backscatter intensity across the pool corresponded with inward cross-stream flow. These suspension indicators were used to orient averaged velocity grids for unambiguously defining the cross-stream velocity magnitudes. Additional field investigations could test whether the correlation between cross-stream velocity and backscatter intensity patterns results from helical recirculation of suspended sediment to the inside of the bend. These river measurements, consistent with classic and recent laboratory studies, show that ADCP surveys can provide refined views of secondary flow and sediment movement in large rivers.

  16. Optical flow based Kalman filter for body joint prediction and tracking using HOG-LBP matching

    NASA Astrophysics Data System (ADS)

    Nair, Binu M.; Kendricks, Kimberley D.; Asari, Vijayan K.; Tuttle, Ronald F.

    2014-03-01

    We propose a real-time novel framework for tracking specific joints in the human body on low resolution imagery using optical flow based Kalman tracker without the need of a depth sensor. Body joint tracking is necessary for a variety of surveillance based applications such as recognizing gait signatures of individuals, identifying the motion patterns associated with a particular action and the corresponding interactions with objects in the scene to classify a certain activity. The proposed framework consists of two stages; the initialization stage and the tracking stage. In the initialization stage, the joints to be tracked are either manually marked or automatically obtained from other joint detection algorithms in the first few frames within a window of interest and appropriate image descriptions of each joint are computed. We employ the use of a well-known image coding scheme known as the Local Binary Patterns (LBP) to represent the joint local region where this image coding removes the variance to non-uniform lighting conditions as well as enhances the underlying edges and corner. The image descriptions of the joint region would then include a histogram computed from the LBP-coded ROI and a HOG (Histogram of Oriented Gradients) descriptor to represent the edge information. Next the tracking stage can be divided into two phases: Optical flow based detection of joints in corresponding frames of the sequence and prediction /correction phases of Kalman tracker with respect to the joint coordinates. Lucas Kanade optical flow is used to locate the individual joints in consecutive frames of the video based on their location in the previous frame. But more often, mismatches can occur due to the rotation of the joint region and the rotation variance of the optical flow matching technique. The mismatch is then determined by comparing the joint region descriptors using Chi-squared metric between a pair of frames and depending on this statistic, either the prediction

  17. [Effect of grass barrier-combined filter strips on the reduction of nitrogen and phosphorus concentration under concentrated flow of varying densities].

    PubMed

    Du, Qin; Wang, Jin-ye; Li, Hai-fang

    2015-09-01

    Vegetative barrier-combined filter strips are defined as grass barriers set up before filter strips. They could make concentrated water flow disperse, which exerts the function of grass barriers (i.e., existence of grass barriers improves the performance of filter strips in the purification of pollutants). In this regards, grass barriers are generally considered to be effective in the purification of pollutants when the density of concentrated flow is low, whereas little was known about this effect with an increasing density of concentrated flow. In this study, we constructed Miscanthus floridulus barrier before Vitex negundo filter strip with three densities of concentrated flow (low: one concentrated flow channel; middle: three channels; high: five channels). The aim of work was to identify the effect of M. floridulus combined V. negundo filter strips in reducing nitrogen and phosphorus concentration under three concentrated water flow levels. Our results showed that the combined filter strips had a higher performance in the reduction in the total N, NH(4+)-N, NO(3-)-N and total P compared to those in the V. negundo (P < 0.05), regardless of the water flow level. There was no significant difference in the reduction of total N, NH(4+)-N, NO(3-)-N and total P among three water flow levels (P > 0.05). We concluded that M. floridulus combined V. negundo filter strips could improve the reduction of nutrients, which couldn' t be influenced by varying density of concentrated flow level.

  18. [Effect of grass barrier-combined filter strips on the reduction of nitrogen and phosphorus concentration under concentrated flow of varying densities].

    PubMed

    Du, Qin; Wang, Jin-ye; Li, Hai-fang

    2015-09-01

    Vegetative barrier-combined filter strips are defined as grass barriers set up before filter strips. They could make concentrated water flow disperse, which exerts the function of grass barriers (i.e., existence of grass barriers improves the performance of filter strips in the purification of pollutants). In this regards, grass barriers are generally considered to be effective in the purification of pollutants when the density of concentrated flow is low, whereas little was known about this effect with an increasing density of concentrated flow. In this study, we constructed Miscanthus floridulus barrier before Vitex negundo filter strip with three densities of concentrated flow (low: one concentrated flow channel; middle: three channels; high: five channels). The aim of work was to identify the effect of M. floridulus combined V. negundo filter strips in reducing nitrogen and phosphorus concentration under three concentrated water flow levels. Our results showed that the combined filter strips had a higher performance in the reduction in the total N, NH(4+)-N, NO(3-)-N and total P compared to those in the V. negundo (P < 0.05), regardless of the water flow level. There was no significant difference in the reduction of total N, NH(4+)-N, NO(3-)-N and total P among three water flow levels (P > 0.05). We concluded that M. floridulus combined V. negundo filter strips could improve the reduction of nutrients, which couldn' t be influenced by varying density of concentrated flow level. PMID:26785568

  19. Penetration of fiber versus spherical particles through filter media and faceseal leakage of N95 filtering facepiece respirators with cyclic flow.

    PubMed

    Cho, Kyungmin Jacob; Turkevich, Leonid; Miller, Matthew; McKay, Roy; Grinshpun, Sergey A; Ha, KwonChul; Reponen, Tiina

    2013-01-01

    This study investigated differences in penetration between fibers and spherical particles through faceseal leakage of an N95 filtering facepiece respirator. Three cyclic breathing flows were generated corresponding to mean inspiratory flow rates (MIF) of 15, 30, and 85 L/min. Fibers had a mean diameter of 1 μm and a median length of 4.9 μm (calculated aerodynamic diameter, d(ae) = 1.73 μm). Monodisperse polystyrene spheres with a mean physical diameter of 1.01 μm (PSI) and 1.54 μm (PSII) were used for comparison (calculated d(ae) = 1.05 and 1.58 μm, respectively). Two optical particle counters simultaneously determined concentrations inside and outside the respirator. Geometric means (GMs) for filter penetration of the fibers were 0.06, 0.09, and 0.08% at MIF of 15, 30, and 85 L/min, respectively. Corresponding values for PSI were 0.07, 0.12, and 0.12%. GMs for faceseal penetration of fibers were 0.40, 0.14, and 0.09% at MIF of 15, 30, and 85 L/min, respectively. Corresponding values for PSI were 0.96, 0.41, and 0.17%. Faceseal penetration decreased with increased breathing rate for both types of particles (p ≤ 0.001). GMs of filter and faceseal penetration of PSII at an MIF of 30 L/min were 0.14% and 0.36%, respectively. Filter penetration and faceseal penetration of fibers were significantly lower than those of PSI (p < 0.001) and PSII (p < 0.003). This confirmed that higher penetration of PSI was not due to slightly smaller aerodynamic diameter, indicating that the shape of fibers rather than their calculated mean aerodynamic diameter is a prevailing factor on deposition mechanisms through the tested respirator. In conclusion, faceseal penetration of fibers and spherical particles decreased with increasing breathing rate, which can be explained by increased capture by impaction. Spherical particles had 2.0-2.8 times higher penetration through faceseal leaks and 1.1-1.5 higher penetration through filter media than fibers, which can be attributed to

  20. Penetration of fiber versus spherical particles through filter media and faceseal leakage of N95 filtering facepiece respirators with cyclic flow.

    PubMed

    Cho, Kyungmin Jacob; Turkevich, Leonid; Miller, Matthew; McKay, Roy; Grinshpun, Sergey A; Ha, KwonChul; Reponen, Tiina

    2013-01-01

    This study investigated differences in penetration between fibers and spherical particles through faceseal leakage of an N95 filtering facepiece respirator. Three cyclic breathing flows were generated corresponding to mean inspiratory flow rates (MIF) of 15, 30, and 85 L/min. Fibers had a mean diameter of 1 μm and a median length of 4.9 μm (calculated aerodynamic diameter, d(ae) = 1.73 μm). Monodisperse polystyrene spheres with a mean physical diameter of 1.01 μm (PSI) and 1.54 μm (PSII) were used for comparison (calculated d(ae) = 1.05 and 1.58 μm, respectively). Two optical particle counters simultaneously determined concentrations inside and outside the respirator. Geometric means (GMs) for filter penetration of the fibers were 0.06, 0.09, and 0.08% at MIF of 15, 30, and 85 L/min, respectively. Corresponding values for PSI were 0.07, 0.12, and 0.12%. GMs for faceseal penetration of fibers were 0.40, 0.14, and 0.09% at MIF of 15, 30, and 85 L/min, respectively. Corresponding values for PSI were 0.96, 0.41, and 0.17%. Faceseal penetration decreased with increased breathing rate for both types of particles (p ≤ 0.001). GMs of filter and faceseal penetration of PSII at an MIF of 30 L/min were 0.14% and 0.36%, respectively. Filter penetration and faceseal penetration of fibers were significantly lower than those of PSI (p < 0.001) and PSII (p < 0.003). This confirmed that higher penetration of PSI was not due to slightly smaller aerodynamic diameter, indicating that the shape of fibers rather than their calculated mean aerodynamic diameter is a prevailing factor on deposition mechanisms through the tested respirator. In conclusion, faceseal penetration of fibers and spherical particles decreased with increasing breathing rate, which can be explained by increased capture by impaction. Spherical particles had 2.0-2.8 times higher penetration through faceseal leaks and 1.1-1.5 higher penetration through filter media than fibers, which can be attributed to

  1. Uncertainty evaluation of coliform bacteria removal from vegetated filter strip under overland flow condition.

    PubMed

    Guber, A K; Yakirevich, A M; Sadeghi, A M; Pachepsky, Y A; Shelton, D R

    2009-01-01

    Vegetated filter strips (VFS) have become an important component of water quality improvement by reducing sediment and nutrients transport to surface water. This management practice is also beneficial for controlling manure-borne pathogen transport to surface water. The objective of this work was to assess the VFS efficiency and evaluate the uncertainty in predicting the microbial pollutant removal from overland flow in VFS. We used the kinematic wave overland flow model as implemented in KINEROS2 coupled with the convective-dispersive overland transport model which accounts for the reversible attachment-detachment and surface straining of infiltrating bacteria. The model was successfully calibrated with experimental data obtained from a series of simulated rainfall experiments at vegetated and bare sandy loam and clay loam plots, where fecal coliforms were released from manure slurry applied on the top of the plots. The calibrated model was then used to assess the sensitivity of the VFS efficiency to the model parameters, rainfall duration, and intensity for a case study with a 6-m VFS placed at the edge of 200-m long field. The Monte Carlo simulations were also performed to evaluate the uncertainty associated with the VFS efficiency given the uncertainty in the model parameters and key inputs. The VFS efficiency was found to be <95% in 25%, <75% in 23%, and <25% in 20% of cases. Relatively long high-intensity rainfalls, low hydraulic conductivities, low net capillary drives of soil, and high soil moisture contents before rainfalls caused the partial failure of VFS to retain coliforms from the infiltration excess runoff.

  2. Grid-Independent Large-Eddy Simulation in Turbulent Channel Flow using Three-Dimensional Explicit Filtering

    NASA Technical Reports Server (NTRS)

    Gullbrand, Jessica

    2003-01-01

    In this paper, turbulence-closure models are evaluated using the 'true' LES approach in turbulent channel flow. The study is an extension of the work presented by Gullbrand (2001), where fourth-order commutative filter functions are applied in three dimensions in a fourth-order finite-difference code. The true LES solution is the grid-independent solution to the filtered governing equations. The solution is obtained by keeping the filter width constant while the computational grid is refined. As the grid is refined, the solution converges towards the true LES solution. The true LES solution will depend on the filter width used, but will be independent of the grid resolution. In traditional LES, because the filter is implicit and directly connected to the grid spacing, the solution converges towards a direct numerical simulation (DNS) as the grid is refined, and not towards the solution of the filtered Navier-Stokes equations. The effect of turbulence-closure models is therefore difficult to determine in traditional LES because, as the grid is refined, more turbulence length scales are resolved and less influence from the models is expected. In contrast, in the true LES formulation, the explicit filter eliminates all scales that are smaller than the filter cutoff, regardless of the grid resolution. This ensures that the resolved length-scales do not vary as the grid resolution is changed. In true LES, the cell size must be smaller than or equal to the cutoff length scale of the filter function. The turbulence-closure models investigated are the dynamic Smagorinsky model (DSM), the dynamic mixed model (DMM), and the dynamic reconstruction model (DRM). These turbulence models were previously studied using two-dimensional explicit filtering in turbulent channel flow by Gullbrand & Chow (2002). The DSM by Germano et al. (1991) is used as the USFS model in all the simulations. This enables evaluation of different reconstruction models for the RSFS stresses. The DMM

  3. Computer program for the analysis of the cross flow in a radial inflow turbine scroll

    NASA Technical Reports Server (NTRS)

    Hamed, A.; Abdallah, S.; Tabakoff, W.

    1977-01-01

    A computer program was used to solve the governing of the potential flow in the cross sectional planes of a radial inflow turbine scroll. A list of the main program, the subroutines, and typical output example are included.

  4. Dilution jets in accelerated cross flows. Ph.D. Thesis Final Report

    NASA Technical Reports Server (NTRS)

    Lipshitz, A.; Greber, I.

    1984-01-01

    Results of flow visualization experiments and measurements of the temperature field produced by a single jet and a row of dilution jets issued into a reverse flow combustor are presented. The flow in such combustors is typified by transverse and longitudinal acceleration during the passage through its bending section. The flow visualization experiments are designed to examine the separate effects of longitudinal and transverse acceleration on the jet trajectory and spreading rate. A model describing a dense single jet in a lighter accelerating cross flow is developed. The model is based on integral conservation equations, including the pressure terms appropriate to accelerating flows. It uses a modified entrainment correlation obtained from previous experiments of a jet in a cross stream. The flow visualization results are compared with the model calculations in terms of trajectories and spreading rates. Each experiment is typified by a set of three parameters: momentum ratio, density ratio and the densimetric Froude number.

  5. Modeling the Air Flow in the 3410 Building Filtered Exhaust Stack System

    SciTech Connect

    Recknagle, Kurtis P.; Barnett, J. Matthew; Suffield, Sarah R.

    2013-01-23

    Additional ventilation capacity has been designed for the 3410 Building filtered exhaust stack system. The updated system will increase the number of fans from two to three and will include ductwork to incorporate the new fan into the existing stack. Stack operations will involve running various two-fan combinations at any given time. The air monitoring system of the existing two-fan stack was previously found to be in compliance with the ANSI/HPS N13.1-1999 standard, however it is not known if the modified (three-fan) system will comply. Subsequently, a full-scale three-dimensional (3-D) computational fluid dynamics (CFD) model of the modified stack system has been created to examine the sampling location for compliance with the standard. The CFD modeling results show good agreement with testing data collected from the existing 3410 Building stack and suggest that velocity uniformity and flow angles will remain well within acceptance criteria when the third fan and associated ductwork is installed. This includes two-fan flow rates up to 31,840 cfm for any of the two-fan combinations. For simulation cases in which tracer gas and particles are introduced in the main duct, the model predicts that both particle and tracer gas coefficients of variance (COVs) may be larger than the acceptable 20 percent criterion of the ANSI/HPS N13.1-1999 standard for each of the two-fan, 31,840 cfm combinations. Simulations in which the tracers are introduced near the fans result in improved, though marginally acceptable, COV values for the tracers. Due to the remaining uncertainty that the stack will qualify with the addition of the third fan and high flow rates, a stationary air blender from Blender Products, Inc. is considered for inclusion in the stack system. A model of the air blender has been developed and incorporated into the CFD model. Simulation results from the CFD model that includes the air blender show striking improvements in tracer gas mixing and tracer particle

  6. Improved design and optimization of subsurface flow constructed wetlands and sand filters

    NASA Astrophysics Data System (ADS)

    Brovelli, A.; Carranza-Díaz, O.; Rossi, L.; Barry, D. A.

    2010-05-01

    Subsurface flow constructed wetlands and sand filters are engineered systems capable of eliminating a wide range of pollutants from wastewater. These devices are easy to operate, flexible and have low maintenance costs. For these reasons, they are particularly suitable for small settlements and isolated farms and their use has substantially increased in the last 15 years. Furthermore, they are also becoming used as a tertiary - polishing - step in traditional treatment plants. Recent work observed that research is however still necessary to understand better the biogeochemical processes occurring in the porous substrate, their mutual interactions and feedbacks, and ultimately to identify the optimal conditions to degrade or remove from the wastewater both traditional and anthropogenic recalcitrant pollutants, such as hydrocarbons, pharmaceuticals, personal care products. Optimal pollutant elimination is achieved if the contact time between microbial biomass and the contaminated water is sufficiently long. The contact time depends on the hydraulic residence time distribution (HRTD) and is controlled by the hydrodynamic properties of the system. Previous reports noted that poor hydrodynamic behaviour is frequent, with water flowing mainly through preferential paths resulting in a broad HRTD. In such systems the flow rate must be decreased to allow a sufficient proportion of the wastewater to experience the minimum residence time. The pollutant removal efficiency can therefore be significantly reduced, potentially leading to the failure of the system. The aim of this work was to analyse the effect of the heterogeneous distribution of the hydraulic properties of the porous substrate on the HRTD and treatment efficiency, and to develop an improved design methodology to reduce the risk of system failure and to optimize existing systems showing poor hydrodynamics. Numerical modelling was used to evaluate the effect of substrate heterogeneity on the breakthrough curves of

  7. Synthetic Jets in Cross-flow. Part 2; Jets From Orifices of Different Geometry

    NASA Technical Reports Server (NTRS)

    Milanovic, Ivana M.; Zaman, K. B. M. Q.

    2003-01-01

    The flow fields of synthetic jets in a cross-flow from orifices of different geometry are investigated. The geometries include a straight, a tapered, a pitched and a cluster of nine orifices, all having the same cross-sectional area through which the perturbation is discharged into the cross-flow. The strength of the jet from the tapered orifice in comparison to that from the straight one is found to be only slightly enhanced. The flow field from the cluster of orifices, when viewed a few equivalent diameters downstream, is similar to that from the single orifice. However, the penetration is somewhat lower in the former case due to the increased mixing of the distributed jets with the cross-flow. The penetration for the pitched configuration is the lowest, as expected. The jet trajectories for the straight and pitched orifices are well represented by correlation equations available for steady jets-in-cross-flow. Distributions of streamwise velocity, vorticity as well as turbulence intensity are documented for various cases. In addition, distributions of phase-averaged velocity and vorticity for the cylindrical and the clustered orifices are presented providing an insight into the flow dynamics.

  8. CFD simulations of the flow control performance applied for inlet of low drag high-bypass turbofan engine at cross flow regimes

    NASA Astrophysics Data System (ADS)

    Kursakov, I. A.; Kazhan, E. V.; Lysenkov, A. V.; Savelyev, A. A.

    2016-10-01

    Paper describes the optimization procedure for low cruise drag inlet of high-bypass ratio turbofan engine (HBRE). The critical cross-flow velocity when the flow separation on the lee side of the inlet channel occurs is determined. The effciency of different flow control devices used to improve the flow parameters at inlet section cross flow regime is analyzed. Boundary layer suction, bypass slot and vortex generators are considered. It is shown that flow control devices enlarge the stability range of inlet performance at cross flow regimes.

  9. Scheduling and Separating Departures Crossing Arrival Flows in Shared Airspace

    NASA Technical Reports Server (NTRS)

    Chevalley, Eric; Parke, Bonny K.; Lee, Paul; Omar, Faisal; Lee, Hwasoo; Beinert, Nancy; Kraut, Joshua M.; Palmer, Everett

    2013-01-01

    Flight efficiency and reduction of flight delays are among the primary goals of NextGen. In this paper, we propose a concept of shared airspace where departures fly across arrival flows, provided gaps are available in these flows. We have explored solutions to separate departures temporally from arrival traffic and pre-arranged procedures to support controllers' decisions. We conducted a Human-in-the-Loop simulation and assessed the efficiency and safety of 96 departures from the San Jose airport (SJC) climbing across the arrival airspace of the Oakland and San Francisco arrival flows. In our simulation, the SJC tower had a tool to schedule departures to fly across predicted gaps in the arrival flow. When departures were mistimed and separation could not be ensured, a safe but less efficient route was provided to the departures to fly under the arrival flows. A coordination using a point-out procedure allowed the arrival controller to control the SJC departures right after takeoff. We manipulated the accuracy of departure time (accurate vs. inaccurate) as well as which sector took control of the departures after takeoff (departure vs. arrival sector) in a 2x2 full factorial plan. Results show that coordination time decreased and climb efficiency increased when the arrival sector controlled the aircraft right after takeoff. Also, climb efficiency increased when the departure times were more accurate. Coordination was shown to be a critical component of tactical operations in shared airspace. Although workload, coordination, and safety were judged by controllers as acceptable in the simulation, it appears that in the field, controllers would need improved tools and coordination procedures to support this procedure.

  10. Ion collision cross section analyses in quadrupole ion traps using the filter diagonalization method: a theoretical study.

    PubMed

    Jiang, Ting; He, Miyi; Guo, Dan; Zhai, Yanbing; Xu, Wei

    2016-04-28

    Previously, we have demonstrated the feasibility of measuring ion collision cross sections (CCSs) within a quadrupole ion trap by performing time-frequency analyses of simulated ion trajectories. In this study, an improved time-frequency analysis method, the filter diagonalization method (FDM), was applied for data analyses. Using the FDM, high resolution could be achieved in both time- and frequency-domains when calculating ion time-frequency curves. Owing to this high-resolution nature, ion-neutral collision induced ion motion frequency shifts were observed, which further cause the intermodulation of ion trajectories and thus accelerate image current attenuation. Therefore, ion trap operation parameters, such as the ion number, high-order field percentage and buffer gas pressure, were optimized for ion CCS measurements. Under optimized conditions, simulation results show that a resolving power from 30 to more than 200 could be achieved for ion CCS measurements. PMID:27066889

  11. Investigation of flow and transport processes at the MADE site using ensemble Kalman filter

    NASA Astrophysics Data System (ADS)

    Liu, Gaisheng; Chen, Yan; Zhang, Dongxiao

    2008-07-01

    In this work the ensemble Kalman filter (EnKF) is applied to investigate the flow and transport processes at the macro-dispersion experiment (MADE) site in Columbus, MS. The EnKF is a sequential data assimilation approach that adjusts the unknown model parameter values based on the observed data with time. The classic advection-dispersion (AD) and the dual-domain mass transfer (DDMT) models are employed to analyze the tritium plume during the second MADE tracer experiment. The hydraulic conductivity ( K), longitudinal dispersivity in the AD model, and mass transfer rate coefficient and mobile porosity ratio in the DDMT model, are estimated in this investigation. Because of its sequential feature, the EnKF allows for the temporal scaling of transport parameters during the tritium concentration analysis. Inverse simulation results indicate that for the AD model to reproduce the extensive spatial spreading of the tritium observed in the field, the K in the downgradient area needs to be increased significantly. The estimated K in the AD model becomes an order of magnitude higher than the in situ flowmeter measurements over a large portion of media. On the other hand, the DDMT model gives an estimation of K that is much more comparable with the flowmeter values. In addition, the simulated concentrations by the DDMT model show a better agreement with the observed values. The root mean square (RMS) between the observed and simulated tritium plumes is 0.77 for the AD model and 0.45 for the DDMT model at 328 days. Unlike the AD model, which gives inconsistent K estimates at different times, the DDMT model is able to invert the K values that consistently reproduce the observed tritium concentrations through all times.

  12. Investigation of flow and transport processes at the MADE site using ensemble Kalman filter

    USGS Publications Warehouse

    Liu, Gaisheng; Chen, Y.; Zhang, Dongxiao

    2008-01-01

    In this work the ensemble Kalman filter (EnKF) is applied to investigate the flow and transport processes at the macro-dispersion experiment (MADE) site in Columbus, MS. The EnKF is a sequential data assimilation approach that adjusts the unknown model parameter values based on the observed data with time. The classic advection-dispersion (AD) and the dual-domain mass transfer (DDMT) models are employed to analyze the tritium plume during the second MADE tracer experiment. The hydraulic conductivity (K), longitudinal dispersivity in the AD model, and mass transfer rate coefficient and mobile porosity ratio in the DDMT model, are estimated in this investigation. Because of its sequential feature, the EnKF allows for the temporal scaling of transport parameters during the tritium concentration analysis. Inverse simulation results indicate that for the AD model to reproduce the extensive spatial spreading of the tritium observed in the field, the K in the downgradient area needs to be increased significantly. The estimated K in the AD model becomes an order of magnitude higher than the in situ flowmeter measurements over a large portion of media. On the other hand, the DDMT model gives an estimation of K that is much more comparable with the flowmeter values. In addition, the simulated concentrations by the DDMT model show a better agreement with the observed values. The root mean square (RMS) between the observed and simulated tritium plumes is 0.77 for the AD model and 0.45 for the DDMT model at 328 days. Unlike the AD model, which gives inconsistent K estimates at different times, the DDMT model is able to invert the K values that consistently reproduce the observed tritium concentrations through all times. ?? 2008 Elsevier Ltd. All rights reserved.

  13. The calibration and operation of a constant-temperature crossed-wire probe in supersonic flow

    NASA Technical Reports Server (NTRS)

    Fernando, E. M.; Donovan, J. F.; Smits, A. J.

    1987-01-01

    The calibration and operation of a constant-temperature crossed-wire probe in supersonic flow is considered. Crossed-wire probes offer considerable advantages over single, inclined wires: the kinematic shear stress can be derived from a single point measurement; the rms quantities can be derived from the same measurement, and the instantaneous quantities can be obtained as a continuous function of time. However, using a crossed-wire probe in supersonic flow is subject to the following practical difficulties: the problem of flow interference, where the shock waves from one wire and its supports interfere with the flow over the other wire; the necessity for high frequency response to resolve the spectral content, and the sensitivity of the results to small changes in the calibration constants. In the present contribution, each of these problems is addressed. Practical solutions are suggested, and some encouraging results are presented.

  14. Flow-through rates and evaluation of solids separation of compost filter socks versus silt fence in sediment control applications.

    PubMed

    Keener, Harold M; Faucette, Britt; Klingman, Michael H

    2007-01-01

    Soil loss rates from construction sites can be 1000 times the average of natural soil erosion rates and 20 times that from agricultural lands. Silt fence (SF) is the current industry standard used to control sediment originating from construction activities. Silt fences are designed to act as miniature detention ponds. Research has indicated that SF sediment filtering efficiency is related to its ability to detain and pond water, not necessarily the filtration ability of the fabric. Design capacity and spacing is based on flow-through rate and design height. In addition, increased detention of runoff and pressure from ponding may increase the likelihood of overtopping or failure of SF in field application. Testing was conducted on compost silt socks (SS) and SF to determine sediment filtering efficiency, flow-through rate, ponding depth, overtopping point, design height, and design capacity. Results indicate flow-through rate changes with time, as does ponding depth, due to the accumulation of solids on/in the sediment filters. Changes in depth with time were a linear function of flow rate after 10 min of flow, up to the time the sediment filter is overtopped. Predicting the capacity of SF and SS to handle runoff without the filter being overtopped requires consideration of both runoff rate and length of runoff time. Data show SS half the heights of SF were less likely to overtop than SF when sediment-laden runoff water flow rates are less than 1.03 L(-1) s(-1) m(-1) (5 gpm/ft, gal per minute per lineal foot). Ponded depth behind a 61.0-cm (24 in) SF increased more rapidly than behind a 30.5-cm diam. (12 in) SS, and at the end of the thirty minutes, the depth behind the SF was 75% greater than that behind the SS. Removal of solids by the SF and the SS were not shown to be statistically different. Results were used to create a Microsoft Excel-based interactive design tool to assist engineers and erosion and sediment control planners on how to specify compost SS

  15. On the Nonlinear Evolution of a Stationary Cross-Flow Vortex in a Fully Three-Dimensional Boundary Layer Flow

    NASA Technical Reports Server (NTRS)

    Gajjar, J. S. B.

    1995-01-01

    We consider the nonlinear stability of a fully three-dimensional boundary layer flow in an incompressible fluid and derive an equation governing the nonlinear development of a stationary cross-flow vortex. The amplitude equation is a novel integro-differential equation which has spatial derivatives of the amplitude occurring in the kernal function. It is shown that the evolution of the cross-flow vortex is strongly coupled to the properties of an unsteady wall layer which is in fact driven by an unknown slip velocity, proportional to the amplitude of the cross-flow vortex. The work is extended to obtain the corresponding equation for rotating disk flow. A number of special cases are examined and the numerical solution for one of cases, and further analysis, demonstrates the existence of finite-distance as well as focussing type singularities. The numerical solutions also indicate the presence of a new type of nonlinear wave solution for a certain set of parameter values.

  16. Numerical analysis of flows of rarefied gases in long channels with octagonal cross section shapes

    SciTech Connect

    Szalmas, L.

    2014-12-09

    Isothermal, pressure driven rarefied gas flows through long channels with octagonal cross section shapes are analyzed computationally. The capillary is between inlet and outlet reservoirs. The cross section is constant along the axial direction. The boundary condition at the solid-gas interface is assumed to be diffuse reflection. Since the channel is long, the gaseous velocity is small compared to the average molecular speed. Consequently, a linearized description can be used. The flow is described by the linearized Bhatnagar-Gross-Krook kinetic model. The solution of the problem is divided into two stages. First, the local flow field is determined by assuming the local pressure gradient. Secondly, the global flow behavior is deduced by the consideration of the conservation of the mass along the axis of the capillary. The kinetic equation is solved by the discrete velocity method on the cross section. Both spatial and velocity spaces are discretized. A body fitted rectangular grid is used for the spatial space. Near the boundary, first-order, while in the interior part of the flow domain, second-order finite-differences are applied to approximate the spatial derivatives. This combination results into an efficient and straightforward numerical treatment. The velocity space is represented by a Gauss-Legendre quadrature. The kinetic equation is solved in an iterative manner. The local dimensionless flow rate is calculated and tabulated for a wide range of the gaseous rarefaction for octagonal cross sections with various geometrical parameters. It exhibits the Knudsen minimum phenomenon. The flow rates in the octagonal channel are compared to those through capillaries with circular and square cross sections. Typical velocity profiles are also shown. The mass flow rate and the distribution of the pressure are determined and presented for global pressure driven flows.

  17. ITP Filter Particulate Decontamination Measurement

    SciTech Connect

    Dworjanyn, L.O.

    1993-05-21

    A new test method was developed which showed the installed In- Tank Precipitation Filter Unit {number_sign}3 provided at least 40, 000 x decontamination of the precipitated potassium tetraphenylborate (KTPB) during the cold chemical runs.This filter is expected to meet the needed 40,000 x hot cesium decontamination requirements, assuming that the cesium precipitate, CsTPB, behaves the same as KTPB. The new method permits cold chemicals field testing of installed filters to quantify particulate decontamination and verify filter integrity before going hot. The method involves a 1000 x concentration of fine particulate KTPB in the filtrate to allow direct analysis by counting for naturally radioactive isotope K-40 using the underground SRTC gamma spectroscopy facility. The particulate concentration was accomplished by ultra filtration at Rhone-Poulenc, NJ, using a small cross-flow bench facility, followed by collection of all suspended solids on a small filter disc for K analysis.

  18. Cross flow induced vibrations in staggered arrays of cylindrical structures

    SciTech Connect

    Marn, J.

    1991-12-31

    Flow induced vibrations cause by instability is the subject of this investigation. The bulk of the work performed is theoretical in nature, the comparison with some of existing experimental data is given for each of four models described. First model encompasses the effects of prescribed motion on the cylinder. Such circumstances occur in the case of vortex shedding initiated instability. The reduced velocity within the cylinder array is low and there is no coupling between the adjacent cylinders. Second model assumes certain form of vibration and corresponding behavior of the perturbed velocity field in temporal and one of spatial coordinates thus transforming partial differential equations into ordinary differential equations and takes into account the motion of the neighboring cylinder. This corresponds to fluid elastic controlled instabilities. The resulting equations are solved analytically. The model is used for better understanding of the equations of cylinder motion as well as for quick estimates of threshold of instability. Third model relaxes an assumption about the form of vibration in spatial direction and uses the vorticity formulation of equation of fluid motion to account for fluid-solid interaction. This model analysis is of two phase (air-water mixture) flow. The void fraction distribution is found to be the single most decisive factor to determine the onset of instability for such a domain. In conclusion, two distinct mechanism were found to be responsible for flow induced vibration caused instabilities, (1) outside source controlled periodic excitation (such as vortex shedding) -- described by the first model and (2) fluid elastic forces -- described by second, third and fourth models. For the values of reduced velocity below 0.7 first model is proposed, for the values above 0.7, the rest.

  19. Crossing turbulent boundaries: interfacial flux in environmental flows.

    PubMed

    Grant, Stanley B; Marusic, Ivan

    2011-09-01

    Advances in the visualization and prediction of turbulence are shedding new light on mass transfer in the turbulent boundary layer. These discoveries have important implications for many topics in environmental science and engineering, from the transport of earth-warming CO2 across the sea-air interface, to nutrient processing and sediment erosion in rivers, lakes, and the ocean, to pollutant removal in water and wastewater treatment systems. In this article we outline current understanding of turbulent boundary layer flows, with particular focus on coherent turbulence and its impact on mass transport across the sediment-water interface in marine and freshwater systems. PMID:21793569

  20. Nonlinear stability of non-stationary cross-flow vortices in compressible boundary layers

    NASA Technical Reports Server (NTRS)

    Gajjar, J. S. B.

    1995-01-01

    The nonlinear evolution of long wavelength non-stationary cross-flow vortices in a compressible boundary layer is investigated and the work extends that of Gajjar (1994) to flows involving multiple critical layers. The basic flow profile considered in this paper is that appropriate for a fully three-dimensional boundary layer with O(1) Mach number and with wall heating or cooling. The governing equations for the evolution of the cross-flow vortex are obtained and some special cases are discussed. One special case includes linear theory where exact analytic expressions for the growth rate of the vortices are obtained. Another special case is a generalization of the Bassom & Gajjar (1988) results for neutral waves to compressible flows. The viscous correction to the growth rate is derived and it is shown how the unsteady nonlinear critical layer structure merges with that for a Haberman type of viscous critical layer.

  1. Dynamic analysis of pedestrian crossing behaviors on traffic flow at unsignalized mid-block crosswalks

    NASA Astrophysics Data System (ADS)

    Liu, Gang; He, Jing; Luo, Zhiyong; Yang, Wunian; Zhang, Xiping

    2015-05-01

    It is important to study the effects of pedestrian crossing behaviors on traffic flow for solving the urban traffic jam problem. Based on the Nagel-Schreckenberg (NaSch) traffic cellular automata (TCA) model, a new one-dimensional TCA model is proposed considering the uncertainty conflict behaviors between pedestrians and vehicles at unsignalized mid-block crosswalks and defining the parallel updating rules of motion states of pedestrians and vehicles. The traffic flow is simulated for different vehicle densities and behavior trigger probabilities. The fundamental diagrams show that no matter what the values of vehicle braking probability, pedestrian acceleration crossing probability, pedestrian backing probability and pedestrian generation probability, the system flow shows the "increasing-saturating-decreasing" trend with the increase of vehicle density; when the vehicle braking probability is lower, it is easy to cause an emergency brake of vehicle and result in great fluctuation of saturated flow; the saturated flow decreases slightly with the increase of the pedestrian acceleration crossing probability; when the pedestrian backing probability lies between 0.4 and 0.6, the saturated flow is unstable, which shows the hesitant behavior of pedestrians when making the decision of backing; the maximum flow is sensitive to the pedestrian generation probability and rapidly decreases with increasing the pedestrian generation probability, the maximum flow is approximately equal to zero when the probability is more than 0.5. The simulations prove that the influence of frequent crossing behavior upon vehicle flow is immense; the vehicle flow decreases and gets into serious congestion state rapidly with the increase of the pedestrian generation probability.

  2. Intensity transform and Wiener filter in measurement of blood flow in arteriography

    NASA Astrophysics Data System (ADS)

    Nunes, Polyana F.; Franco, Marcelo L. N.; Filho, João. B. D.; Patrocínio, Ana C.

    2015-03-01

    Using the arteriography examination, it is possible to check anomalies in blood vessels and diseases such as stroke, stenosis, bleeding and especially in the diagnosis of Encephalic Death in comatose individuals. Encephalic death can be diagnosed only when there is complete interruption of all brain functions, and hence the blood stream. During the examination, there may be some interference on the sensors, such as environmental factors, poor maintenance of equipment, patient movement, among other interference, which can directly affect the noise produced in angiography images. Then, we need to use digital image processing techniques to minimize this noise and improve the pixel count. Therefore, this paper proposes to use median filter and enhancement techniques for transformation of intensity using the sigmoid function together with the Wiener filter so you can get less noisy images. It's been realized two filtering techniques to remove the noise of images, one with the median filter and the other with the Wiener filter along the sigmoid function. For 14 tests quantified, including 7 Encephalic Death and 7 other cases, the technique that achieved a most satisfactory number of pixels quantified, also presenting a lesser amount of noise, is the Wiener filter sigmoid function, and in this case used with 0.03 cuttof.

  3. Transport and survival of bacterial and viral tracers through submerged-flow constructed wetland and sand-filter system.

    PubMed

    Vega, Everardo; Lesikar, Bruce; Pillai, Suresh D

    2003-08-01

    Untreated or improperly treated wastewater has often been cited as the primary contamination source of groundwater. The use of decentralized wastewater treatment systems has applicability around the world since it obviates the need for extensive infrastructure development and expenditures. The use of a submerged flow constructed wetland (CW) and a sand filter to remove bacterial and viral pathogens from wastewater streams was evaluated in this study Salmonella sp. and a bacteriophages tracer were used in conjunction with the conservative bromide tracer to understand the fate and transport of these organisms in these treatment systems. Viral breakthrough numbers in the sand filter and CW were similar with a Spearman Rank correlation of 0.8 (P<0.05). In the CW, the virus exhibited almost a 3-log reduction, while in the sand filter, the viruses exhibited a 2-log reduction. The bacterial tracers, however, did not exhibit similar reductions. Low numbers of bacteria and viruses were still detectable in the effluent streams suggesting that disinfection of the effluent is critical. The survival of the tracer bacteria and viruses was as expected dependent on the biotic and abiotic conditions existing within the wastewater. The results suggest that the microbial removal characteristics of decentralized wastewater treatment systems can vary and depend on factors such as adsorption, desorption and inactivation which in turn depend on the design specifics such as filter media characteristics and local climatic conditions.

  4. Transport and survival of bacterial and viral tracers through submerged-flow constructed wetland and sand-filter system.

    PubMed

    Vega, Everardo; Lesikar, Bruce; Pillai, Suresh D

    2003-08-01

    Untreated or improperly treated wastewater has often been cited as the primary contamination source of groundwater. The use of decentralized wastewater treatment systems has applicability around the world since it obviates the need for extensive infrastructure development and expenditures. The use of a submerged flow constructed wetland (CW) and a sand filter to remove bacterial and viral pathogens from wastewater streams was evaluated in this study Salmonella sp. and a bacteriophages tracer were used in conjunction with the conservative bromide tracer to understand the fate and transport of these organisms in these treatment systems. Viral breakthrough numbers in the sand filter and CW were similar with a Spearman Rank correlation of 0.8 (P<0.05). In the CW, the virus exhibited almost a 3-log reduction, while in the sand filter, the viruses exhibited a 2-log reduction. The bacterial tracers, however, did not exhibit similar reductions. Low numbers of bacteria and viruses were still detectable in the effluent streams suggesting that disinfection of the effluent is critical. The survival of the tracer bacteria and viruses was as expected dependent on the biotic and abiotic conditions existing within the wastewater. The results suggest that the microbial removal characteristics of decentralized wastewater treatment systems can vary and depend on factors such as adsorption, desorption and inactivation which in turn depend on the design specifics such as filter media characteristics and local climatic conditions. PMID:12676500

  5. Does Kutta lift exist on a vortex ring in a uniform cross flow?

    NASA Astrophysics Data System (ADS)

    Lim, T. T.; Lua, K. B.; Thet, K.

    2008-05-01

    Past works [Y. K. Chang and A. D. Vakili, Phys. Fluids 7, 1583 (1995); R. Sau and K. Mahesh, AIAA Paper No. 2007-1316] show that a vortex ring ejected normal to a cross flow tilts and deforms as it propagates downstream, and they attribute this phenomenon to the Kutta lift or Magnus effect. Here, we show through a controlled experiment that there is no physical evidence of the existence of a Kutta lift when a fully developed vortex ring is exposed to a uniform cross flow. The observed phenomenon could be attributed to the modification of vorticity distribution of the vortex core due to the combined effect of the cross flow itself and the entrainment of boundary layer material during the formation of vortex ring.

  6. Groundwater flow inverse modeling in non-MultiGaussian media: performance assessment of the normal-score Ensemble Kalman Filter

    NASA Astrophysics Data System (ADS)

    Li, L.; Zhou, H.; Hendricks Franssen, H. J.; Gómez-Hernández, J. J.

    2011-07-01

    The normal-score ensemble Kalman filter (NS-EnKF) is tested on a synthetic aquifer characterized by the presence of channels with a bimodal distribution of its hydraulic conductivities. Fourteen scenarios are analyzed which differ among them in one or various of the following aspects: the prior random function model, the boundary conditions of the flow problem, the number of piezometers used in the assimilation process, or the use of covariance localization in the implementation of the Kalman filter. The performance of the NS-EnKF is evaluated through the ensemble mean and variance maps, the connectivity patterns of the individual conductivity realizations and the degree of reproduction of the piezometric heads. The results show that (i) the localized NS-EnKF can identify correctly the channels when a large number of conditioning piezometers are used even when an erroneous prior random function model is used, (ii) localization plays an important role to prevent filter inbreeding and results in a better logconductivity characterization, and (iii) the NS-EnKF works equally well under very different flow configurations.

  7. Groundwater flow inverse modeling in non-MultiGaussian media: performance assessment of the normal-score Ensemble Kalman Filter

    NASA Astrophysics Data System (ADS)

    Li, L.; Zhou, H.; Hendricks Franssen, H. J.; Gómez-Hernández, J. J.

    2012-02-01

    The normal-score ensemble Kalman filter (NS-EnKF) is tested on a synthetic aquifer characterized by the presence of channels with a bimodal distribution of its hydraulic conductivities. This is a clear example of an aquifer that cannot be characterized by a multiGaussian distribution. Fourteen scenarios are analyzed which differ among them in one or various of the following aspects: the prior random function model, the boundary conditions of the flow problem, the number of piezometers used in the assimilation process, or the use of covariance localization in the implementation of the Kalman filter. The performance of the NS-EnKF is evaluated through the ensemble mean and variance maps, the connectivity patterns of the individual conductivity realizations and the degree of reproduction of the piezometric heads. The results show that (i) the localized NS-EnKF can characterize the non-multiGaussian underlying hydraulic distribution even when an erroneous prior random function model is used, (ii) localization plays an important role to prevent filter inbreeding and results in a better logconductivity characterization, and (iii) the NS-EnKF works equally well under very different flow configurations.

  8. An experimental study of plasma aerodynamic actuation on a round jet in cross flow

    NASA Astrophysics Data System (ADS)

    Dai, Sheng-ji; Xiao, Yang; He, Li-ming; Jin, Tao; Zhang, Qian; Hou, Peng-hui; Zhao, Zi-chen

    2015-03-01

    The present paper is performed on the effect of plasma aerodynamic actuation on a round jet in cross flow field with a low Reynolds number by using smoke visualization. The actuator is constituted by an electrode pair separated by a dielectric Al2O3 sheet. Several AC supply conditions are utilized. The experimental result shows a closing-in tendency of the jet flow toward the wall after being induced by plasma aerodynamic actuation, and such tendency is increasingly intensified as the actuation voltage increases. Numerical simulation is also performed. The simulation results show that an induced vortex pair is generated by plasma aerodynamic actuation near the wall flow field. The rotation direction of the induced vortex pair reverses against the counter-rotating vortex pair generated by a round jet in a cross flow without plasma aerodynamic actuation. Then the strength and structural size of the counter-rotating vortex pair are significantly reduced, resulting in the intensified near-wall effect of the jet flow. Three electrode-typed actuators (straight, 150°-elliptic arc and 180°-elliptic arc with the same streamwise extent) are placed at the exit of round jet to research the influence of electrode structure on jet in cross flow. The result shows that the longer the arc electrode surrounding the hole, the stronger the induced jet that flow near the wall is.

  9. Moving Granular Bed Filter Development Program

    SciTech Connect

    Wilson, K.B.; Haas, J.C.; Eshelman, M.B.

    1992-11-01

    The granular bed filter was developed through low pressure, high temperature (1600{degrees}F) testing in the late 1970`s and early 1980`s`. Collection efficiencies over 99% were obtained. In 1988, high pressure, high temperature testing was completed at New York University, Westbury, N.Y., utilizing a coal-fired pressurized, fluidized bed combustor. High particulate removal efficiencies were confirmed as it was shown that both New Source Performance Standards and turbine tolerance limits could be met. The early scale-up work of the granular bed filter indicated potential limitations due to size, cost, and mechanical complexity. These limitations were addressed in the present program by utilizing the information gained from the filter development up through the NYU test program to reassess the commercial approach. Two studies were chosen for developing conceptual designs and cost estimates of the commercial sized filters. One is the economic study of the 250 MWe, second generation pressurized fluidized bed combustion plant defined by Foster Wheeler. This plant originally included cross-flow filters for hot gas cleanup. The other plant under study is a 100 MWe, airblown KRW gasifier. A cross-flow inter was utilized for gas stream cleanup in this study also. Granular bed and ceramic candle filters were substituted for the cross-flow filters in both these plants, and the resulting cost of electricity (COE) is compared.

  10. Moving Granular Bed Filter Development Program

    SciTech Connect

    Wilson, K.B.; Haas, J.C.; Eshelman, M.B.

    1992-01-01

    The granular bed filter was developed through low pressure, high temperature (1600[degrees]F) testing in the late 1970's and early 1980's'. Collection efficiencies over 99% were obtained. In 1988, high pressure, high temperature testing was completed at New York University, Westbury, N.Y., utilizing a coal-fired pressurized, fluidized bed combustor. High particulate removal efficiencies were confirmed as it was shown that both New Source Performance Standards and turbine tolerance limits could be met. The early scale-up work of the granular bed filter indicated potential limitations due to size, cost, and mechanical complexity. These limitations were addressed in the present program by utilizing the information gained from the filter development up through the NYU test program to reassess the commercial approach. Two studies were chosen for developing conceptual designs and cost estimates of the commercial sized filters. One is the economic study of the 250 MWe, second generation pressurized fluidized bed combustion plant defined by Foster Wheeler. This plant originally included cross-flow filters for hot gas cleanup. The other plant under study is a 100 MWe, airblown KRW gasifier. A cross-flow inter was utilized for gas stream cleanup in this study also. Granular bed and ceramic candle filters were substituted for the cross-flow filters in both these plants, and the resulting cost of electricity (COE) is compared.

  11. The CA model for traffic-flow at the grade roundabout crossing

    NASA Astrophysics Data System (ADS)

    Chen, Rui-Xiong; Bai, Ke-Zhao; Liu, Mu-Ren

    2006-07-01

    The cellular automaton model is suggested to describe the traffic-flow at the grade roundabout crossing. After the simulation with computer, the fundamental properties of this model have been revealed. Analysing this kind of road structure, this paper transforms the grade roundabout crossing with inner-roundabout-lane and outer-roundabout-lane into a configuration with many bottlenecks. Because of the self-organization, the traffic flow remains unblocked under a certain vehicle density. Some results of the simulation are close to the actual design parameter.

  12. The impact of mass flow and masking on the pressure drop of air filter in heavy-duty diesel engine

    NASA Astrophysics Data System (ADS)

    Hoseeinzadeh, Sepideh; Gorji-Bandpy, Mofid

    2012-04-01

    This paper presents a computational fluid dynamics (CFD) calculation approach to predict and evaluate the impact of the mass-flow inlet on the pressure drop of turbocharger`s air filtfer in heavy-duty diesel engine. The numerical computations were carried out using a commercial CFD program whereas the inlet area of the air filter consisted of several holes connected to a channel. After entering through the channel, the air passes among the holes and enters the air filter. The effect of masking holes and hydraulic diameter is studied and investigated on pressure drop. The results indicate that pressure drop increase with decreasing of hydraulic diameter and masking of the holes has considerable affect on the pressure drop.

  13. Effect of Fuselage Cross Sections on Aerodynamic Characteristics of Reusable Launch Vehicles in Subsonic Flow

    NASA Astrophysics Data System (ADS)

    Tadakuma, Kenji; Morita, Wataru; Aso, Shigeru; Tani, Yasuhiro

    An experimental study on aerodynamic effect of RLVs (Reusable Launch Vehicles) due to fuselage cross sections has been conducted in subsonic flow. Three fuselage models and two wing-body models have been considered. Fuselage models have a circular, a square and a triangular cross section. Wing-body models have a square and a triangular cross section with wings. Experiments have been conducted under test conditions of free-stream Mach number M∞=0.3 and Reynolds number Re=3.2×106. Aerodynamic forces are measured and flow fields are visualized by smoke-wire technique and oil-flow technique. Results show that fuselage cross sections have much effect on whole aerodynamic characteristics, the fuselage model with a triangular cross section has higher lift coefficient in high angle of attack region than that of the other fuselage models and the wing-body model with a triangular fuselage cross section does not stall till high angle of attack region compared with the “Square” fuselage wing-body model.

  14. Flow Style Investigation and Noise Reduction of a Cross-Flow Fan with Varied Rotor-Skew-Angle Rotor

    NASA Astrophysics Data System (ADS)

    Tsai, Go-Long; Tu, Tsung-Hsien; Li, Tung-Chen; Wang, Kuang-Hsieng

    The purpose of this study was investigating the noise emission, flow-style, fan’s performance regarding to cross-fan with three different rotor-skew angle (RSA) rotors. The special flow visualization setups for both vertical and parallel investigation of smoke slice were used to overcome the blind sight of a Laser-Doppler or a particle-tracking velocimeter, and the three-dimensional flow differences were confirmed with streamline images. The experimental results indicated that RSA-5, which is a rotor with a nearly a pitch skew within blade’s two end shrouds, has a lower sound emission and little pressure drops relative to that of no skew angle case, RSA-0. RSA-10, two pitches twisting case, also has a better acoustics quietness than that of RSA-0, but it excited undesired noise in a high frequency components around 2-4kHz. In this work, for a compromise between flow and acoustics performances, RSA-5 shows the most suitable design for cross-flow fan rotor.

  15. Cross-Spectral Signatures in Global Helioseismology Data of Large-Scale Flow in the Sun

    NASA Astrophysics Data System (ADS)

    Woodard, M. F.

    2005-05-01

    Large-scale flows in the Sun's interior have been studied using a variety of helioseismic techniques, including spectral analysis of spherical harmonic time series of photospheric velocity oscillations. Detailed maps of differential rotation have been obtained from measurements of the frequencies of resonance peaks in the power spectra. Flows can also affect power spectra in subtler ways, e.g., by their influence on the widths of resonance peaks. In addition to their spectral signature, flows and other aspherical perturbations also produce cross-spectral signatures, via the mode-coupling effect of a flow. Cross power spectra of time series of coefficients in the spherical-harmonic decomposition of SOHO/MDI medium-ℓ velocity images have been computed and are being compared with theoretical predictions. The results of a preliminary comparison of observed and theoretically predicted cross spectra for differential rotation and meridional circulation will be presented. A program to systematically map large-scale solar internal flow using cross-spectral data will be described. The author acknowledges useful discussions with colleagues, especially Doug Braun, Yuhong Fan, Aaron Birch, and Jesper Schou. He is also grateful to Jesper Schou for help in acquiring MDI data products and to NASA for support under contract NAS5-3114. The Solar Oscillations Investigation- Michelson Doppler Imager experiment on SOHO is supported by NASA contract NAG5-3077 at Stanford University. SOHO is a project of international cooperation between ESA and NASA.

  16. Active ultrasonic cross-correlation flowmeters for mixed-phase pipe flows

    NASA Astrophysics Data System (ADS)

    Sheen, S. H.; Raptis, A. C.

    Two ultrasonic flowmeters which employ the active cross-correlation technique and use a simple clamp-on transducer arrangement are discussed. The flowmeter for solid/liquid flows was tested over a wide range of coal concentration in water and oil. The measured velocity based on the peak position of the cross-correlation function is consistently higher by about 15% than the average velocity measured by flow diversion. The origin of the difference results mainly from the flow velocity profiles and the transit-time probability distribution. The flowmeter that can measure particle velocity in a solid/gas flow requires acoustic decoupling arrangement between two sensing stations. The measured velocity is mainly associated with the particles near the wall. Performance of both flowmeters is presented.

  17. Numerical studies on flow fields around buildings in an Urban street canyon and cross-road

    NASA Astrophysics Data System (ADS)

    Cheng, Xueling; Hu, Fei

    2005-03-01

    The questions on how vortices are constructed and on the relationship between the flow patterns and concentration distributions in real street canyons are the most pressing questions in pollution control studies. In this paper, the very large eddy simulation (VLES) and large eddy simulation (LES) are applied to calculate the flow and pollutant concentration fields in an urban street canyon and a cross-road respectively. It is found that the flow separations are not only related to the canyon aspect ratios, but also with the flow velocities and wall temperatures. And the turbulent dispersions are so strongly affected by the flow fields that the pollutant concentration distributions can be distinguished from the different aspect ratios, flow velocities and wall temperatures.

  18. Improving Efficiency of a Counter-Current Flow Moving Bed Granular Filter

    SciTech Connect

    Colver, G.M.; Brown, R.C.; Shi, H.; Soo, D.S-C.

    2002-09-18

    The goal of this research is to improve the performance of moving bed granular filters for gas cleaning at high temperatures and pressures. A second goal of the research is to optimize the performances of both solids and gas filtering processes through appropriate use of granular bed materials, particle sizes, feed rates etc. in a factorial study. These goals are directed toward applications of advanced coal-fired power cycles under development by the U.S. Department of Energy including pressurized fluidized bed combustion and integrated gasification/combined cycles based on gas turbines and fuel cells. Only results for particulate gas cleaning are reported here.

  19. Pressure-Velocity-Scalar Filtered Mass Density Function for Large Eddy Simulation of Compressible Turbulent Flow

    NASA Astrophysics Data System (ADS)

    Nouri Gheimassi, Arash; Givi, Peyman; Nik, Mehdi B.; Pope, Stephen B.

    2015-11-01

    A new model is developed which accounts for the effects of subgrid scale pressure in the context of the filtered density function (FDF) formulation. This results in a pressure-velocity-scalar filtered mass density function (PVS-FMDF), which is suitable for large eddy simulation of compressible turbulence. Following its mathematical definition, an exact transport equation is derived for the PVS-FMDF. This equation is modeled in a probabilistic manner by a system of stochastic differential equations (SDEs). The consistency and the predictive capability of the model are established by conducting LES of a three-dimensional compressible mixing layer, and comparison with direct numerical simulation (DNS) data.

  20. An analytical solution for Dean flow in curved ducts with rectangular cross section

    NASA Astrophysics Data System (ADS)

    Norouzi, M.; Biglari, N.

    2013-05-01

    In this paper, a full analytical solution for incompressible flow inside the curved ducts with rectangular cross-section is presented for the first time. The perturbation method is applied to solve the governing equations and curvature ratio is considered as the perturbation parameter. The previous perturbation solutions are usually restricted to the flow in curved circular or annular pipes related to the overly complex form of solutions or singularity situation for flow in curved ducts with non-circular shapes of cross section. This issue specifies the importance of analytical studies in the field of Dean flow inside the non-circular ducts. In this study, the main flow velocity, stream function of lateral velocities (secondary flows), and flow resistance ratio in rectangular curved ducts are obtained analytically. The effect of duct curvature and aspect ratio on flow field is investigated as well. Moreover, it is important to mention that the current analytical solution is able to simulate the Taylor-Görtler and Dean vortices (vortices in stable and unstable situations) in curved channels.

  1. Bubble Formation from Wall Orifice in Liquid Cross-Flow Under Low Gravity

    NASA Technical Reports Server (NTRS)

    Nahra, Henry K.; Kamotani, Y.

    2000-01-01

    Two-phase flows present a wide variety of applications for spacecraft thermal control systems design. Bubble formation and detachment is an integral part of the two phase flow science. The objective of the present work is to experimentally investigate the effects of liquid cross-flow velocity, gas flow rate, and orifice diameter on bubble formation in a wall-bubble injection configuration. Data were taken mainly under reduced gravity conditions but some data were taken in normal gravity for comparison. The reduced gravity experiment was conducted aboard the NASA DC-9 Reduced Gravity Aircraft. The results show that the process of bubble formation and detachment depends on gravity, the orifice diameter, the gas flow rate, and the liquid cross-flow velocity. The data are analyzed based on a force balance, and two different detachment mechanisms are identified. When the gas momentum is large, the bubble detaches from the injection orifice as the gas momentum overcomes the attaching effects of liquid drag and inertia. The surface tension force is much reduced because a large part of the bubble pinning edge at the orifice is lost as the bubble axis is tilted by the liquid flow. When the gas momentum is small, the force balance in the liquid flow direction is important, and the bubble detaches when the bubble axis inclination exceeds a certain angle.

  2. In-vessel fluid flow measurements using thermocouples cross-correlation.

    SciTech Connect

    NguyenLe, Q.

    1998-05-08

    Fluid flow rate in high temperature and pressure vessels can be difficult to measure due to the associated harsh environment, inaccessible locations and pressure boundary integrity concerns. However, by using quick response miniature thermocouples to measure the naturally occurring temperature variations within the flow, the fluid velocity can be inferred from the transit time analysis. This flow measurement technique has other advantages such as the flow profile is not significantly disturbed, no additional flow restrictions introduced and the system fiction factor is not increased. Furthermore, since the measured flow rate is generally unaffected by the global system dynamics, such as heat increases or losses, as well as changes in the flow regimes, the location of the thermocouple pairs is extremely flexible. Due to the mentioned advantages, the thermocouple cross-correlation flow measurement method has been developed for use at the Purdue University Multi-Dimensional Integral Test Assembly (PUMA). Currently, thermocouple cross-correlation technique is used to measure the Reactor Pressure Vessel downcomer fluid velocity and the suppression pool in-vessel natural circulation velocity.

  3. Renin release and autoregulation of blood flow in a new model of non-filtering non-transporting kidney.

    PubMed

    Sanowski, J; Wocial, B

    1977-04-01

    1. A recently developed model of a non-filtering, non-transporting dog kidney, obtained by an in situ filling of tubules with low-viscosity oil, was applied for studies of renin release and autoregulation of renal blood flow (RBF). 2. Renal blood flow was partially autoregulated after oil blockade of tubules, as indicated by a mean autoregulation index (Semple-de Wardener (1959) of 0-5. This was comparable to autoregulation of the stop-flow kidney (index 0-6) and contrasted with abolition of autoregulation after hypertonic mannitol loading at stop-flow conditions (index 1-1). 3. The aortic construction at a suprarenal level, which decreased renal perfusion pressure of the oil-blocked kidney 35 +/- (S.E. of mean) 6 mmHg, produced an increase in arterial plasma renin activity of 1-8 +/- 0-1 ng. ml.-1 (P less than 0-02). Renin secretion rate decreased 33 to 70 ng.min-1 in three dogs in which renal perfusion pressure was reduced to 60--66 mmHg, but increased 110 +/- 41 ng.min-1 when pressure reductions were kept within the renal blood flow autoregulation range (n=8, P less than 0-025). 4. These results suggest that signals from the tubular receptor (macula densa) are not necessary for stimulation of renin release or autoregulation of renal blood flow.

  4. Extended Kalman filter method for state of charge estimation of vanadium redox flow battery using thermal-dependent electrical model

    NASA Astrophysics Data System (ADS)

    Xiong, Binyu; Zhao, Jiyun; Wei, Zhongbao; Skyllas-Kazacos, Maria

    2014-09-01

    State of charge (SOC) estimation is a key issue for battery management since an accurate estimation method can ensure safe operation and prevent the over-charge/discharge of a battery. Traditionally, open circuit voltage (OCV) method is utilized to estimate the stack SOC and one open flow cell is needed in each battery stack [1,2]. In this paper, an alternative method, extended Kalman filter (EKF) method, is proposed for SOC estimation for VRBs. By measuring the stack terminal voltages and applied currents, SOC can be predicted with a state estimator instead of an additional open circuit flow cell. To implement EKF estimator, an electrical model is required for battery analysis. A thermal-dependent electrical circuit model is proposed to describe the charge/discharge characteristics of the VRB. Two scenarios are tested for the robustness of the EKF. For the lab testing scenarios, the filtered stack voltage tracks the experimental data despite the model errors. For the online operation, the simulated temperature rise is observed and the maximum SOC error is within 5.5%. It is concluded that EKF method is capable of accurately predicting SOC using stack terminal voltages and applied currents in the absence of an open flow cell for OCV measurement.

  5. Theoretical study of the effect of liquid desiccant mass flow rate on the performance of a cross flow parallel-plate liquid desiccant-air dehumidifier

    NASA Astrophysics Data System (ADS)

    Mohammad, Abdulrahman Th.; Mat, Sohif Bin; Sulaiman, M. Y.; Sopian, K.; Al-abidi, Abduljalil A.

    2013-11-01

    A computer simulation using MATLAB is investigated to predict the distribution of air stream parameters (humidity ratio and temperature) as well as desiccant parameters (temperature and concentration) inside the parallel plate absorber. The present absorber consists of fourteen parallel plates with a surface area per unit volume ratio of 80 m2/m3. Calcium chloride as a liquid desiccant flows through the top of the plates to the bottom while the air flows through the gap between the plates making it a cross flow configuration. The model results show the effect of desiccant mass flow rate on the performance of the dehumidifier (moisture removal and dehumidifier effectiveness). Performance comparisons between present cross-flow dehumidifier and another experimental cross-flow dehumidifier in the literature are carried out. The simulation is expected to help in optimizing of a cross flow dehumidifier.

  6. Treatment of petrochemical secondary effluent by an up-flow biological aerated filter (BAF).

    PubMed

    Fu, L Y; Wu, C Y; Zhou, Y X; Zuo, J E; Ding, Y

    2016-01-01

    In this study, petrochemical secondary effluent was treated by a 55 cm diameter pilot-scale biological aerated filter (BAF) with a media depth of 220 cm. Volcanic rock grains were filled as the BAF media. Median removal efficiency of chemical oxygen demand (COD) and ammonia nitrogen (NH3-N) was 29.35 and 57.98%, respectively. Moreover, the removal profile of the COD, NH3-N, total nitrogen and total organic carbon demonstrated that the filter height of 140 cm made up to 90% of the total removal efficiency of the final effluent. By gas chromatography-mass spectrometry, removal efficiencies of 2-chloromethyl-1,3-dioxolane, and benzonitrile, indene and naphthalene were obtained, ranging from 30.12 to 63.01%. The biomass and microbial activity of the microorganisms on the filter media were in general reduced with increasing filter height, which is consistent with the removal profile of the contaminants. The detected genera Defluviicoccus, Betaproteobacteria_unclassified and the Blastocatella constituted 1.86-6.75% of the identified gene, enhancing the COD and nitrogen removal in BAF for treating petrochemical secondary effluent. PMID:27120658

  7. Treatment of petrochemical secondary effluent by an up-flow biological aerated filter (BAF).

    PubMed

    Fu, L Y; Wu, C Y; Zhou, Y X; Zuo, J E; Ding, Y

    2016-01-01

    In this study, petrochemical secondary effluent was treated by a 55 cm diameter pilot-scale biological aerated filter (BAF) with a media depth of 220 cm. Volcanic rock grains were filled as the BAF media. Median removal efficiency of chemical oxygen demand (COD) and ammonia nitrogen (NH3-N) was 29.35 and 57.98%, respectively. Moreover, the removal profile of the COD, NH3-N, total nitrogen and total organic carbon demonstrated that the filter height of 140 cm made up to 90% of the total removal efficiency of the final effluent. By gas chromatography-mass spectrometry, removal efficiencies of 2-chloromethyl-1,3-dioxolane, and benzonitrile, indene and naphthalene were obtained, ranging from 30.12 to 63.01%. The biomass and microbial activity of the microorganisms on the filter media were in general reduced with increasing filter height, which is consistent with the removal profile of the contaminants. The detected genera Defluviicoccus, Betaproteobacteria_unclassified and the Blastocatella constituted 1.86-6.75% of the identified gene, enhancing the COD and nitrogen removal in BAF for treating petrochemical secondary effluent.

  8. Cross-flow blowing of a two-dimensional stationary arc.

    NASA Technical Reports Server (NTRS)

    Bose, T. K.

    1971-01-01

    It is demonstrated in an analysis that the electrons emitted from the cathode undergo collisions with the heavy particles and are deflected in the flow direction by the component of a collisional force associated with the relative difference in flow velocities between electrons and heavy particles. The resultant motion of the electrons describing the arc is thus caused by a combined action of the collisional force that results from the externally applied electric field. An expression is given which enables computation of the arc shape to be made provided the velocity distribution of the cross-flow and the distribution of the externally applied electric field are prescribed.

  9. Generation of two-dimensional vortices in a cross-flow

    NASA Technical Reports Server (NTRS)

    Samaniego, Jean-Michel

    1993-01-01

    The present report is concerned with an experimental study on the generation of plane two-dimensional vortices in a cross-flow. The purpose of this work is to address the problem of the feasibility of a two-dimensional experiment of flame-vortex interactions.

  10. Numerical Study on Influence of Cross Flow on Rewetting of AHWR Fuel Bundle

    PubMed Central

    Kumar, Mithilesh; Mukhopadhyay, D.; Ghosh, A. K.; Kumar, Ravi

    2014-01-01

    Numerical study on AHWR fuel bundle has been carried out to assess influence of circumferential and cross flow rewetting on the conduction heat transfer. The AHWR fuel bundle quenching under accident condition is designed primarily with radial jets at several axial locations. A 3D (r, θ, z) transient conduction fuel pin model has been developed to carry out the study with a finite difference method (FDM) technique with alternating direction implicit (ADI) scheme. The single pin has been considered to study effect of circumferential conduction and multipins have been considered to study the influence of cross flow. Both analyses are carried out with the same fluid temperature and heat transfer coefficients as boundary conditions. It has been found from the analyses that, for radial jet, the circumferential conduction is significant and due to influence of overall cross flow the reductions in fuel temperature in the same quench plane in different rings are different with same initial surface temperature. Influence of cross flow on rewetting is found to be very significant. Outer fuel pins rewetting time is higher than inner. PMID:24672341

  11. Flow field measurements in a crossing shockwave turbulent boundary layer interaction at Mach 3

    NASA Technical Reports Server (NTRS)

    Lachowicz, Jason T.; Chokani, Ndaona

    1993-01-01

    An experimental study has been conducted to examine the flow field of the 3D crossing shock wave/turbulent boundary layer interaction. A symmetric pair of 9-deg fins were used to generate the crossing shocks. The incoming boundary layer was developed on the tunnel sidewall and thus was relatively thick, 0.49 arcsec, and suited for pitot probe surveys. The test conditions were a nominal Mach number of 3 and unit Reynolds number of 1.2 x 10 exp 7/ft. The measurements obtained included surface oil flow visualizations, surface static pressures, and boundary layer pitot pressure profiles. The results showed that downstream of the crossing shock intersection, the stagnation pressure losses were significant and the stagnation pressure profiles were highly nonuniform. Despite the severe shock disturbances, the law of the wall and the law of the wake were found to give relatively good agreement with the experimental data.

  12. Cellular automata model for urban road traffic flow considering pedestrian crossing street

    NASA Astrophysics Data System (ADS)

    Zhao, Han-Tao; Yang, Shuo; Chen, Xiao-Xu

    2016-11-01

    In order to analyze the effect of pedestrians' crossing street on vehicle flows, we investigated traffic characteristics of vehicles and pedestrians. Based on that, rules of lane changing, acceleration, deceleration, randomization and update are modified. Then we established two urban two-lane cellular automata models of traffic flow, one of which is about sections with non-signalized crosswalk and the other is on uncontrolled sections with pedestrians crossing street at random. MATLAB is used for numerical simulation of the different traffic conditions; meanwhile space-time diagram and relational graphs of traffic flow parameters are generated and then comparatively analyzed. Simulation results indicate that when vehicle density is lower than around 25 vehs/(km lane), pedestrians have modest impact on traffic flow, whereas when vehicle density is higher than about 60 vehs/(km lane), traffic speed and volume will decrease significantly especially on sections with non-signal-controlled crosswalk. The results illustrate that the proposed models reconstruct the traffic flow's characteristic with the situation where there are pedestrians crossing and can provide some practical reference for urban traffic management.

  13. Reducing cross-sectional data using a genetic algorithm method and effects on cross-section geometry and steady-flow profiles

    USGS Publications Warehouse

    Berenbrock, Charles E.

    2015-01-01

    The effects of reduced cross-sectional data points on steady-flow profiles were also determined. Thirty-five cross sections of the original steady-flow model of the Kootenai River were used. These two methods were tested for all cross sections with each cross section resolution reduced to 10, 20 and 30 data points, that is, six tests were completed for each of the thirty-five cross sections. Generally, differences from the original water-surface elevation were smaller as the number of data points in reduced cross sections increased, but this was not always the case, especially in the braided reach. Differences were smaller for reduced cross sections developed by the genetic algorithm method than the standard algorithm method.

  14. Inexpensive cross-flow hydropower turbine at the Arbuckle Mountain Hydroelectric Project

    SciTech Connect

    Not Available

    1989-11-01

    The Arbuckle Mountain Hydroelectric Project represents a Cooperative Agreement between the US Department of Energy (DOE) and Ron and Carlene Ott. The purpose of the project was to build, install in a hydro project, and intensively test an inexpensive American-made cross-flow turbine and to provide information to the DOE on the costs, efficiency, operation, and maintenance of the unit. The data gained from the research and development project will assist in development of cost-effective technology for low-head small hydro sites. The turbine was designed to reduce the cost of manufacturing while making maximum use of the power available in a remote flashy northern California stream. Even with extensive field modifications, the cost of the unit was much less than those quoted by foreign manufacturers for the same site. The new type of cross-flow turbine developed uses an innovative automatic flow control sliding device which allows the unit to produce power at flow ranges of less than 6% of design flow. This coupled with the infinite flow adjustment feature allows detailed flow regulation needed for small run-of-river projects. The field efficiency testing, the subject of this report, was conducted by Ott Engineering, Inc. in 1988 and early 1989. The tests showed the turbine to have efficiencies in the high seventies and with improvements could reach the efficiencies touted by the European manufacturers of 85% and still be relatively inexpensive to manufacture. It was also found during the tests that the vacuum and depth of water on the runner had a pronounced effect on the turbine output and it is recommended that future research be conducted on these effects, especially for high-vacuum cross-flow turbines. 3 refs.

  15. Remediation of groundwater contaminated with MTBE and benzene: the potential of vertical-flow soil filter systems.

    PubMed

    van Afferden, Manfred; Rahman, Khaja Z; Mosig, Peter; De Biase, Cecilia; Thullner, Martin; Oswald, Sascha E; Müller, Roland A

    2011-10-15

    Field investigations on the treatment of MTBE and benzene from contaminated groundwater in pilot or full-scale constructed wetlands are lacking hugely. The aim of this study was to develop a biological treatment technology that can be operated in an economic, reliable and robust mode over a long period of time. Two pilot-scale vertical-flow soil filter eco-technologies, a roughing filter (RF) and a polishing filter (PF) with plants (willows), were operated independently in a single-stage configuration and coupled together in a multi-stage (RF+PF) configuration to investigate the MTBE and benzene removal performances. Both filters were loaded with groundwater from a refinery site contaminated with MTBE and benzene as the main contaminants, with a mean concentration of 2970±816 and 13,966±1998 μg L(-1), respectively. Four different hydraulic loading rates (HLRs) with a stepwise increment of 60, 120, 240 and 480 L m(-2) d(-1) were applied over a period of 388 days in the single-stage operation. At the highest HLR of 480 L m(-2) d(-1), the mean concentrations of MTBE and benzene were found to be 550±133 and 65±123 μg L(-1) in the effluent of the RF. In the effluent of the PF system, respective mean MTBE and benzene concentrations of 49±77 and 0.5±0.2 μg L(-1) were obtained, which were well below the relevant MTBE and benzene limit values of 200 and 1 μg L(-1) for drinking water quality. But a dynamic fluctuation in the effluent MTBE concentration showed a lack of stability in regards to the increase in the measured values by nearly 10%, which were higher than the limit value. Therefore, both (RF+PF) filters were combined in a multi-stage configuration and the combined system proved to be more stable and effective with a highly efficient reduction of the MTBE and benzene concentrations in the effluent. Nearly 70% of MTBE and 98% of benzene were eliminated from the influent groundwater by the first vertical filter (RF) and the remaining amount was almost

  16. Fluorescence cross-correlation spectroscopy for time dependent flows: a numerical investigation

    NASA Astrophysics Data System (ADS)

    Ceffa, Nicolo'G.; Pozzi, Paolo; Bouzin, Margaux; Marquezin, Cassia A.; Sironi, Laura; D'Alfonso, Laura; Collini, Maddalena; Chirico, Giuseppe

    2015-03-01

    We have previously addressed experimentally blood fluidodynamics in microcapillaries by coupling optical microscopy to pixelated detection. By computing the Cross-Correlation Function (CCF) of signals coming from pixels at a distance along the flow we obtained information on the flow speed and direction. The extension of these experiments to more complex systems with high branching of capillaries and/or inverted flows needs a theoretical investigation that we present here. We focus first on straight capillaries and harmonic flows between a minimum Vmin ≠ 0 and a maximum Vmax flow speed. The CCF shows multiple peaks at lag times that correspond closely to the maximum and minimum flow speeds. The general analytical expression of the CCF is given, the position of its maxima are discussed by means of geometrical considerations and numerical analysis and an experimental validation are presented. The second case that we study is the flow in the branches of a y-shaped junction in a microcapillary. By simply modeling the branching in laminar flow (low Reynold numbers) and assuming a smooth transition of speeds along the branches we derive a simple numerical model to compute the trajectories of micro-beads. We estimate the flow speed in the branches by computing the CCFs between linear regions of interest set perpendicular to the axes of the branches.

  17. Ensemble kalman filtering to perform data assimilation with soil water content probes and pedotransfer functions in modeling water flow in variably saturated soils

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Data from modern soil water contents probes can be used for data assimilation in soil water flow modeling, i.e. continual correction of the flow model performance based on observations. The ensemble Kalman filter appears to be an appropriate method for that. The method requires estimates of the unce...

  18. The role of loading rate, backwashing, water and air velocities in an up-flow nitrifying tertiary filter.

    PubMed

    Vigne, Emmanuelle; Choubert, Jean-Marc; Canler, Jean-Pierre; Heduit, Alain; Sørensen, Kim Helleshøj; Lessard, Paul

    2011-01-01

    The vertical distribution of nitrification performances in an up-flow biological aerated filter operated at tertiary nitrification stage is evaluated in this paper. Experimental data were collected from a semi-industrial pilot-plant under various operating conditions. The actual and the maximum nitrification rates were measured at different levels inside the up-flow biofilter. A nitrogen loading rate higher than 1.0 kg NH4-Nm(-3)_mediad(-1) is necessary to obtain nitrification activity over all the height of the biofilter. The increase in water and air velocities from 6 to 10 m h(-1) and 10 to 20 m h(-1) has increased the nitrification rate by 80% and 20% respectively. Backwashing decreases the maximum nitrification rate in the media by only 3-14%. The nitrification rate measured at a level of 0.5 m above the bottom of the filter is four times higher than the applied daily average volumetric nitrogen loading rate up to 1.5 kg NH4-N m(-3)_mediad(-1). Finally, it is shown that 58% of the available nitrification activity is mobilized in steady-state conditions while up to 100% is used under inflow-rate increase.

  19. Wastewater reuse in on-site wastewater treatment: bacteria and virus movement in unsaturated flow through sand filter.

    PubMed

    Sélas, B; Lakel, A; Andres, Y; Le Cloirec, P

    2003-01-01

    In on-site wastewater treatment plants, effluents are pre-treated by septic tank and treated by soil infiltration or sand filtration systems, with unsaturated flow conditions. These systems remove efficiently carbon, nitrogen and suspended solids. But for microbial pollution, the treatment efficiency depends on the hydrodynamic behaviour and filtering media characteristics. Contamination of superficial water and groundwater due to pathogenic viruses and pathogenic bacteria is responsible for many diseases. The objective of this study is to approach the mechanisms and operating conditions to control bacteria and virus release in the environment. Experiments were carried out on reactors of different length packed with sand. Hydraulic load of 90 cm x d(-1) with a pulse periodic flow was used. The influence of chemical composition of the solution on the treatment efficiency has also been studied. For the first time, the residence time distribution (RTD) has been studied using a conservative tracer (KI), to determine the main hydrodynamic parameters. For the second time, the RTD with bacterial and viral tracers (E. coli, bacteriophage MS2) was applied, with the aim to define microbial behaviour in filtering media, including adsorption and filtration phenomena. This work allowed us to determine retardation factors according to the hydraulic loads and chemical composition.

  20. TOMOGRAPHY OF PLASMA FLOWS IN THE UPPER SOLAR CONVECTION ZONE USING TIME-DISTANCE INVERSION COMBINING RIDGE AND PHASE-SPEED FILTERING

    SciTech Connect

    Svanda, Michal

    2013-09-20

    The consistency of time-distance inversions for horizontal components of the plasma flow on supergranular scales in the upper solar convection zone is checked by comparing the results derived using two k-{omega} filtering procedures-ridge filtering and phase-speed filtering-commonly used in time-distance helioseismology. I show that both approaches result in similar flow estimates when finite-frequency sensitivity kernels are used. I further demonstrate that the performance of the inversion improves (in terms of a simultaneously better averaging kernel and a lower noise level) when the two approaches are combined together in one inversion. Using the combined inversion, I invert for horizontal flows in the upper 10 Mm of the solar convection zone. The flows connected with supergranulation seem to be coherent only for the top {approx}5 Mm; deeper down there is a hint of change of the convection scales toward structures larger than supergranules.

  1. Progress Toward Affordable High Fidelity Combustion Simulations Using Filtered Density Functions for Hypersonic Flows in Complex Geometries

    NASA Technical Reports Server (NTRS)

    Drozda, Tomasz G.; Quinlan, Jesse R.; Pisciuneri, Patrick H.; Yilmaz, S. Levent

    2012-01-01

    Significant progress has been made in the development of subgrid scale (SGS) closures based on a filtered density function (FDF) for large eddy simulations (LES) of turbulent reacting flows. The FDF is the counterpart of the probability density function (PDF) method, which has proven effective in Reynolds averaged simulations (RAS). However, while systematic progress is being made advancing the FDF models for relatively simple flows and lab-scale flames, the application of these methods in complex geometries and high speed, wall-bounded flows with shocks remains a challenge. The key difficulties are the significant computational cost associated with solving the FDF transport equation and numerically stiff finite rate chemistry. For LES/FDF methods to make a more significant impact in practical applications a pragmatic approach must be taken that significantly reduces the computational cost while maintaining high modeling fidelity. An example of one such ongoing effort is at the NASA Langley Research Center, where the first generation FDF models, namely the scalar filtered mass density function (SFMDF) are being implemented into VULCAN, a production-quality RAS and LES solver widely used for design of high speed propulsion flowpaths. This effort leverages internal and external collaborations to reduce the overall computational cost of high fidelity simulations in VULCAN by: implementing high order methods that allow reduction in the total number of computational cells without loss in accuracy; implementing first generation of high fidelity scalar PDF/FDF models applicable to high-speed compressible flows; coupling RAS/PDF and LES/FDF into a hybrid framework to efficiently and accurately model the effects of combustion in the vicinity of the walls; developing efficient Lagrangian particle tracking algorithms to support robust solutions of the FDF equations for high speed flows; and utilizing finite rate chemistry parametrization, such as flamelet models, to reduce

  2. Vibration of a tube bundle in two-phase Freon cross-flow

    SciTech Connect

    Pettigrew, M.J.; Taylor, C.E.; Jong, J.H.; Currie, I.G.

    1995-11-01

    Two-phase cross-flow exists in many shell-and-tube heat exchangers. The U-bend region of nuclear steam generators is a prime example. Testing in two-phase flow simulated by air-water provides useful results inexpensively. However, two-phase flow parameters, in particular surface tension and density ratio, are considerably different in air-water than in steam-water. A reasonable compromise is testing in liquid-vapor Freon, which is much closer to steam-water while much simpler experimentally. This paper presents the first results of a series of tests on the vibration behavior of tube bundles subjected to two-phase Freon cross-flow. A rotated triangular tube bundle of tube-to-diameter ratio of 1.5 was tested over a broad range of void fractions and mass fluxes. Fluidelastic instability, random turbulence excitation, and damping were investigated. Well-defined fluidelastic instabilities were observed in continuous two-phase flow regimes. However, intermittent two-phase flow regimes had a dramatic effect on fluidelastic instability. Generally, random turbulence excitation forces are much lower in Freon than in air-water. Damping is very dependent on void fraction, as expected.

  3. Oscillating flow and heat transfer in a channel with sudden cross section change

    NASA Technical Reports Server (NTRS)

    Ibrahim, Mounir; Hashim, Waqar

    1993-01-01

    We have computationally examined oscillating flow (zero mean) between two parallel plates with a sudden change in cross section. The flow was assumed to be laminar incompressible with the inflow velocity uniform over the channel cross section but varying sinusoidally with time. The cases studied cover wide ranges of Re(sub max) (from 187.5 to 2000), Va (from 1 to 10.66), the expansion ratio (1:2 and 1:4) and A(sub r) (2 and 4). Also, three different geometric cases were discussed: (1) asymmetric expansion/contraction; (2) symmetric expansion/contraction; and (3) symmetric blunt body. For these oscillating flow conditions, the fluid undergoes sudden expansion in one-half of the cycle and sudden contraction inthe other half. The instantaneous friction factor, for some ranges of Re(sub max) and Va, deviated substantially from the steady-state friction factor for the same flow parameters. A region has been identified below which the flow is laminar quasi-steady. A videotape showing computer simulations of the oscillating flow demonstrates the usefulness of the current analyses in providing information on the transient hydraulic phenomena.

  4. Evaluation of alkanolamine solutions for carbon dioxide removal in cross-flow rotating packed beds.

    PubMed

    Lin, Chia-Chang; Lin, Yu-Hong; Tan, Chung-Sung

    2010-03-15

    The removal of CO(2) from a 10 vol% CO(2) gas by chemical absorption with 30 wt% alkanolamine solutions containing monoethanolamine (MEA), piperazine (PZ), and 2-amino-2-methyl-1-propanol (AMP) in the cross-flow rotating packed bed (RPB) was investigated. The CO(2) removal efficiency increased with rotor speed, liquid flow rate and inlet liquid temperature. However, the CO(2) removal efficiency decreased with gas flow rate. Also, the CO(2) removal efficiency was independent of inlet gas temperature. The 30 wt% alkanolamine solutions containing PZ with MEA were the appropriate absorbents compared with the single alkanolamine (MEA, AMP) and the mixed alkanolamine solutions containing AMP with MEA. A higher portion of PZ in alkanolamine solutions was more favorable to CO(2) removal. Owing to less contact time in the cross-flow RPB, alkanolamines having high reaction rates with CO(2) are suggested to be used. For the mixed alkanolamine solution containing 12 wt% PZ and 18 wt% MEA, the highest gas flow rate allowed to achieve the CO(2) removal efficiency more than 90% at a liquid flow rate of 0.54 L/min was of 29 L/min. The corresponding height of a transfer unit (HTU) was found to be less than 5.0 cm, lower than that in the conventional packed bed.

  5. Applications of moving granular-bed filters to advanced systems

    SciTech Connect

    Wilson, K.W.; Haas, J.C.; Eshelman, M.B.

    1993-09-01

    The contract is arranged as a base contract with three options. The objective of the base contract is to develop conceptual design(s) of moving granular bed filter and ceramic candle filter technology for control of particles from integrated gasification combined cycle (IGCC) systems, pressurized fluidized-bed combustors (PFBC), and direct coal fueled turbine (DCFT) environments. The conceptual design(s) of these filter technologies are compared, primarily from an economic perspective. The granular bed filter was developed through low pressure, high temperature (1600{degree}F) testing in the late 1970`s and early 1980`s. Collection efficiencies over 99% were obtained. In 1988, high pressure, high temperature testing was completed at New York University, Westbury, N.Y., utilizing a two advanced power generating plants were chosen for developing conceptual designs and cost estimates of the commercial sized filters. One is the 450 MWe, second generation pressurized fluidized bed combustion plant defined by Foster Wheeler. This plant originally included cross-flow filters for hot gas cleanup. The other plant under study is a 100 MWe, KRW air blown gasifier. A cross-flow filter was utilized for gas stream cleanup in this study also. Granular bed and ceramic candle filters were substituted for the cross-flow filters in both these plants, and the resulting costs were compared.

  6. A critical evaluation of various methods for the analysis of flow-solid interaction in a nest of thin cylinders subjected to cross flows

    NASA Technical Reports Server (NTRS)

    Kim, Sang-Wook

    1987-01-01

    Various experimental, analytical, and numerical analysis methods for flow-solid interaction of a nest of cylinders subjected to cross flows are reviewed. A nest of cylinders subjected to cross flows can be found in numerous engineering applications including the Space Shuttle Maine Engine-Main Injector Assembly (SSME-MIA) and nuclear reactor heat exchangers. Despite its extreme importance in engineering applications, understanding of the flow-solid interaction process is quite limited and design of the tube banks are mostly dependent on experiments and/or experimental correlation equations. For future development of major numerical analysis methods for the flow-solid interaction of a nest of cylinders subjected to cross flow, various turbulence models, nonlinear structural dynamics, and existing laminar flow-solid interaction analysis methods are included.

  7. Numerical Simulations of a Reacting Sonic Jet in a Supersonic Cross-flow

    NASA Astrophysics Data System (ADS)

    Attal, Nitesh; Ramaprabhu, Praveen

    2014-11-01

    Interaction of a jet with a background cross-flow is a situation common to many engineering systems, including combustors in SCRAMJETS, gas turbines etc. Such an interaction enhances fuel-air mixing through the distortion of coherent structures into counter-rotating vortex pairs that are tilted, stretched and then sundered by the velocity gradient in the cross-flow, eventually leading to turbulent mixing. The ignition process and flame characteristics depend sensitively on the extent and efficiency of this turbulent mixing process. We describe results from detailed 3D numerical simulations of a sonic circular jet of diameter (D = 0.5 cm) issuing a mixture of H2 (Fuel) diluted with 50% N2 at 300 K into a turbulent, Mach 2 cross-flow of air at 1200 K. The simulations were performed in a computational domain of 20 × 16 × 16 jet diameters using the compressible flow code FLASH, with modifications to handle detailed (H2-O2) chemistry and temperature-dependent material properties. We discuss the role of shock driven mixing, ignition and flame anchoring on the combustion efficiency of the system.

  8. Recirculating electric air filter

    DOEpatents

    Bergman, W.

    1985-01-09

    An electric air filter cartridge has a cylindrical inner high voltage electrode, a layer of filter material, and an outer ground electrode formed of a plurality of segments moveably connected together. The outer electrode can be easily opened to remove or insert filter material. Air flows through the two electrodes and the filter material and is exhausted from the center of the inner electrode.

  9. Recirculating electric air filter

    DOEpatents

    Bergman, Werner

    1986-01-01

    An electric air filter cartridge has a cylindrical inner high voltage eleode, a layer of filter material, and an outer ground electrode formed of a plurality of segments moveably connected together. The outer electrode can be easily opened to remove or insert filter material. Air flows through the two electrodes and the filter material and is exhausted from the center of the inner electrode.

  10. Scale-adaptive simulation of a hot jet in cross flow

    NASA Astrophysics Data System (ADS)

    Duda, B. M.; Menter, F. R.; Hansen, T.; Esteve, M.-J.

    2011-12-01

    The simulation of a hot jet in cross flow is of crucial interest for the aircraft industry as it directly impacts aircraft safety and global performance. Due to the highly transient and turbulent character of this flow, simulation strategies are necessary that resolve at least a part of the turbulence spectrum. The high Reynolds numbers for realistic aircraft applications do not permit the use of pure Large Eddy Simulations as the spatial and temporal resolution requirements for wall bounded flows are prohibitive in an industrial design process. For this reason, the hybrid approach of the Scale-Adaptive Simulation is employed, which retains attached boundary layers in well-established RANS regime and allows the resolution of turbulent fluctuations in areas with sufficient flow instabilities and grid refinement. To evaluate the influence of the underlying numerical grid, three meshing strategies are investigated and the results are validated against experimental data.

  11. Effect of Surface Energy Pulses on Supersonic Flow in a Channel of Variable Cross Section

    NASA Astrophysics Data System (ADS)

    Zamuraev, V. P.; Kalinina, A. P.

    2016-05-01

    The influence of a surface pulse-periodic supply of energy on the formation of shock-wave structures in a plane channel of variable cross section has been studied. Energy is supplied to the constant cross-section units of the channel with the flow Mach number M = 2. The time-average supplied power corresponds to the combustion of hydrogen with the excess-air coefficient from 1 to 10. The problem is solved within the framework of the Euler equations. A dimensionless approach is used to analyze the effect of sources. The applicability of the analytical relations obtained is confirmed by numerical solution of two-dimensional Euler equations.

  12. Proposal for Blood-Flow Imaging by Contrast Echo Using Counter-Crossed Beams

    NASA Astrophysics Data System (ADS)

    Eura, T.; Yoshida, K.; Watanabe, Y.; Takayasu, T.; Nakamura, K.; Akiyama, I.

    We propose a new contrast-echo method using counter-crossed beams of two ultrasonic frequencies as an ultrasound diagnostic for cancer. We call this the Counter-Cross Beam Contrast-Echo (C-CBCE) method. Sum and difference frequency components derived from nonlinear vibration of the contrast agents (microbubbles) driven by dual-frequency ultrasound are used in the C-CBCE method. In this study, we used Sonazoid microbubbles as we attempted to detect the sum frequency component generated by Sonazoid fixed in agar gel. We also measured the in-channel flow velocity of the Sonazoid.

  13. Cross-flow turbines: physical and numerical model studies towards improved array simulations

    NASA Astrophysics Data System (ADS)

    Wosnik, M.; Bachant, P.

    2015-12-01

    Cross-flow, or vertical-axis turbines, show potential in marine hydrokinetic (MHK) and wind energy applications. As turbine designs mature, the research focus is shifting from individual devices towards improving turbine array layouts for maximizing overall power output, i.e., minimizing wake interference for axial-flow turbines, or taking advantage of constructive wake interaction for cross-flow turbines. Numerical simulations are generally better suited to explore the turbine array design parameter space, as physical model studies of large arrays at large model scale would be expensive. However, since the computing power available today is not sufficient to conduct simulations of the flow in and around large arrays of turbines with fully resolved turbine geometries, the turbines' interaction with the energy resource needs to be parameterized, or modeled. Most models in use today, e.g. actuator disk, are not able to predict the unique wake structure generated by cross-flow turbines. Experiments were carried out using a high-resolution turbine test bed in a large cross-section tow tank, designed to achieve sufficiently high Reynolds numbers for the results to be Reynolds number independent with respect to turbine performance and wake statistics, such that they can be reliably extrapolated to full scale and used for model validation. To improve parameterization in array simulations, an actuator line model (ALM) was developed to provide a computationally feasible method for simulating full turbine arrays inside Navier--Stokes models. The ALM predicts turbine loading with the blade element method combined with sub-models for dynamic stall and flow curvature. The open-source software is written as an extension library for the OpenFOAM CFD package, which allows the ALM body force to be applied to their standard RANS and LES solvers. Turbine forcing is also applied to volume of fluid (VOF) models, e.g., for predicting free surface effects on submerged MHK devices. An

  14. Analysis on Experimental Investigation and Mathematical Modeling of Incompressible Flow Through Ceramic Foam Filters

    NASA Astrophysics Data System (ADS)

    Akbarnejad, Shahin; Jonsson, Lage Tord Ingemar; Kennedy, Mark William; Aune, Ragnhild Elizabeth; Jönsson, Pӓr Göran

    2016-08-01

    This paper presents experimental results of pressure drop measurements on 30, 50, and 80 pores per inch (PPI) commercial alumina ceramic foam filters (CFF) and compares the obtained pressure drop profiles to numerically modeled values. In addition, it is aimed at investigating the adequacy of the mathematical correlations used in the analytical and the computational fluid dynamics (CFD) simulations. It is shown that the widely used correlations for predicting pressure drop in porous media continuously under-predict the experimentally obtained pressure drop profiles. For analytical predictions, the negative deviations from the experimentally obtained pressure drop using the unmodified Ergun and Dietrich equations could be as high as 95 and 74 pct, respectively. For the CFD predictions, the deviation to experimental results is in the range of 84.3 to 88.5 pct depending on filter PPI. Better results can be achieved by applying the Forchheimer second-order drag term instead of the Brinkman-Forchheimer drag term. Thus, the final deviation of the CFD model estimates lie in the range of 0.3 to 5.5 pct compared to the measured values.

  15. Influence of cross-flow on nonlinear Tollmien-Schlichting/vortex interaction

    NASA Technical Reports Server (NTRS)

    Davis, D. A. R.; Smith, F. T.

    1994-01-01

    The transition of an incompressible three-dimensional boundary layer with strong cross-flow is considered theoretically and computationally in the context of vortex/wave interactions. Specifically the work centers on two lower-branch Tollmien-Schlichting waves which mutually interact nonlinearly to induce a longitudinal vortex flow. The vortex motion in turn gives rise to significant wave modulation via wall-shear forcing. The characteristic Reynolds number is large and, as a consequence, the waves' and the vortex motion are governed primarily by triple deck theory. The nonlinear interaction is captured by a viscous partial-differential system for the vortex coupled with a pair of amplitude equations for each wave pressure. Following analysis and computation over a wide range of parameters, three distinct responses are found to emerge in the nonlinear behavior of the flow solution downstream: an algebraic finite-distance singularity, far-downstream saturation or far-downstream wave decay leaving pure vortex flow. These depend on the input conditions, the wave angles and the size of the cross flow.

  16. A Numerical Simulation of a Normal Sonic Jet into a Hypersonic Cross-Flow

    NASA Technical Reports Server (NTRS)

    Jeffries, Damon K.; Krishnamurthy, Ramesh; Chandra, Suresh

    1997-01-01

    This study involves numerical modeling of a normal sonic jet injection into a hypersonic cross-flow. The numerical code used for simulation is GASP (General Aerodynamic Simulation Program.) First the numerical predictions are compared with well established solutions for compressible laminar flow. Then comparisons are made with non-injection test case measurements of surface pressure distributions. Good agreement with the measurements is observed. Currently comparisons are underway with the injection case. All the experimental data were generated at the Southampton University Light Piston Isentropic Compression Tube.

  17. Methods for numerical study of tube bundle vibrations in cross-flows

    NASA Astrophysics Data System (ADS)

    Longatte, E.; Bendjeddou, Z.; Souli, M.

    2003-11-01

    In many industrial applications, mechanical structures like heat exchanger tube bundles are subjected to complex flows causing possible vibrations and damage. Part of fluid forces are coupled with tube motion and the so-called fluid-elastic forces can affect the structure dynamic behaviour generating possible instabilities and leading to possible short term failures through high amplitude vibrations. Most classical fluid force identification methods rely on structure response experimental measurements associated with convenient data processes. Owing to recent improvements in Computational Fluid Dynamics, numerical simulation of flow-induced vibrations is now practicable for industrial purposes. The present paper is devoted to the numerical identification of fluid-elastic effects affecting tube bundle motion in presence of fluid at rest and one-phase cross-flows. What is the numerical process? When fluid-elastic effects are not significant and are restricted to added mass effects, there is no strong coupling between structure and fluid motions. The structure displacement is not supposed to affect flow patterns. Thus it is possible to solve flow and structure problems separately by using a fixed nonmoving mesh for the fluid dynamic computation. Power spectral density and time record of lift and drag forces acting on tube bundles can be computed numerically by using an unsteady fluid computation involving for example a large Eddy simulation. Fluid force spectra or time record can then be introduced as inlet conditions into the structure code providing the tube dynamic response generated by flow. Such a computation is not possible in presence of strong flow structure coupling. When fluid-elastic effects cannot be neglected, in presence of tube bundles subjected to cross-flows for example, a coupling between flow and structure computations is required. Appropriate numerical methods are investigated in the present work. The purpose is to be able to provide a numerical

  18. Filter type rotor for multistation photometer

    DOEpatents

    Shumate, II, Starling E.

    1977-07-12

    A filter type rotor for a multistation photometer is provided. The rotor design combines the principle of cross-flow filtration with centrifugal sedimentation so that these occur simultaneously as a first stage of processing for suspension type fluids in an analytical type instrument. The rotor is particularly useful in whole-blood analysis.

  19. Cross-flow deep fat frying and its effect on fry quality distribution and mobility.

    PubMed

    van Koerten, K N; Schutyser, M A I; Somsen, D; Boom, R M

    2016-04-01

    Conventional industrial frying systems are not optimised towards homogeneous product quality, which is partly related to poor oil distribution across the packed bed of fries. In this study we investigate an alternative frying system with an oil cross-flow from bottom to top through a packed bed of fries. Fluidization of rectangular fries during frying was characterised with a modified Ergun equation. Mixing was visualized by using two coloured layers of fries and quantified in terms of mixing entropy. Smaller fries mixed quickly during frying, while longer fries exhibited much less mixing, which was attributed to the higher minimum fluidization velocity and slower dehydration for longer fries. The cross-flow velocity was found an important parameter for the homogeneity of the moisture content of fries. Increased oil velocities positively affected moisture distribution due to a higher oil refresh rate. However, inducing fluidization caused the moisture distribution to become unpredictable due to bed instabilities. PMID:27413220

  20. Cross-flow deep fat frying and its effect on fry quality distribution and mobility.

    PubMed

    van Koerten, K N; Schutyser, M A I; Somsen, D; Boom, R M

    2016-04-01

    Conventional industrial frying systems are not optimised towards homogeneous product quality, which is partly related to poor oil distribution across the packed bed of fries. In this study we investigate an alternative frying system with an oil cross-flow from bottom to top through a packed bed of fries. Fluidization of rectangular fries during frying was characterised with a modified Ergun equation. Mixing was visualized by using two coloured layers of fries and quantified in terms of mixing entropy. Smaller fries mixed quickly during frying, while longer fries exhibited much less mixing, which was attributed to the higher minimum fluidization velocity and slower dehydration for longer fries. The cross-flow velocity was found an important parameter for the homogeneity of the moisture content of fries. Increased oil velocities positively affected moisture distribution due to a higher oil refresh rate. However, inducing fluidization caused the moisture distribution to become unpredictable due to bed instabilities.

  1. Physical and Numerical Model Studies of Cross-flow Turbines Towards Accurate Parameterization in Array Simulations

    NASA Astrophysics Data System (ADS)

    Wosnik, M.; Bachant, P.

    2014-12-01

    Cross-flow turbines, often referred to as vertical-axis turbines, show potential for success in marine hydrokinetic (MHK) and wind energy applications, ranging from small- to utility-scale installations in tidal/ocean currents and offshore wind. As turbine designs mature, the research focus is shifting from individual devices to the optimization of turbine arrays. It would be expensive and time-consuming to conduct physical model studies of large arrays at large model scales (to achieve sufficiently high Reynolds numbers), and hence numerical techniques are generally better suited to explore the array design parameter space. However, since the computing power available today is not sufficient to conduct simulations of the flow in and around large arrays of turbines with fully resolved turbine geometries (e.g., grid resolution into the viscous sublayer on turbine blades), the turbines' interaction with the energy resource (water current or wind) needs to be parameterized, or modeled. Models used today--a common model is the actuator disk concept--are not able to predict the unique wake structure generated by cross-flow turbines. This wake structure has been shown to create "constructive" interference in some cases, improving turbine performance in array configurations, in contrast with axial-flow, or horizontal axis devices. Towards a more accurate parameterization of cross-flow turbines, an extensive experimental study was carried out using a high-resolution turbine test bed with wake measurement capability in a large cross-section tow tank. The experimental results were then "interpolated" using high-fidelity Navier--Stokes simulations, to gain insight into the turbine's near-wake. The study was designed to achieve sufficiently high Reynolds numbers for the results to be Reynolds number independent with respect to turbine performance and wake statistics, such that they can be reliably extrapolated to full scale and used for model validation. The end product of

  2. Inexpensive cross-flow hydropower turbine at Arbuckle Mountain Hydroelectric Project: Final construction and cost report

    SciTech Connect

    Not Available

    1988-07-01

    The Arbuckle Mountain Hydroelectric Project is a Cooperative Agreement between the US Department of Energy (DOE) and Ron and Carlene Ott. The project's purpose is to build and intensively test an inexpensive American-made cross-flow turbine and to provide information to DOE on the cost, efficiency, operation and maintenance of the unit. This final report discusses the technical and financial aspects of planning, designing, manufacturing, and installing the turbine as well as design and construction details of the site.

  3. Cross-terminator ion flow in the ionospheres of Mars and Venus

    NASA Astrophysics Data System (ADS)

    Fraenz, Markus; Dubinin, Eduard; Angsmann, Anne; Nielsen, Erling; Woch, Joachim; Barabash, Stas; Lundin, Rickard; Fedorov, A.

    The upper ionospheres of Mars and Venus are permeated by the magnetic fields induced by the solar wind. It is a long-standing question wether these fields can put the dense ionospheric plasma into motion. If so, the cross-terminator flow of the upper ionosphere could explain a significant part of the ion escape from the planets atmospheres. But it has been technically very challenging to measure the ion flow at energies below 20eV. The only such measurements have been made by the ORPA instrument of the Pioneer Venus Orbiter reporting speeds of 1-5km/s for O+ ions at Venus above 300km altitude at the terminator (Knudsen et al, GRL 1982). At Venus the flow has been explained by the pressure gradient force between dayside and nightside. It can explain the ion supply to the nightside ionosphere. At Mars comparable measurements have never been made. We here report on new measurements of the cross-terminator ion flow at Mars by the ASPERA 3 experiment onboard Mars Express with support from the MARSIS radar experiment which confirm O+ flow speeds of around 6km/s with fluxes of 1.2 ∗ 109 /cm2 s. We also discuss the complicated influence of the spacecraft potential on low energy measurements. At Mars the nightside ionosphere is much weaker than on Venus and the escape velocity only 5km/s. This means that the observed flow leads to escape from the planet. We discuss the implication of these new observation on the total ion escape and possible extensions of the analysis to dayside observations which might allow us to infer the flow structure imposed by the induced magnetic field. We then discuss the observational situation at Venus where the ASPERA-4 instrument allows similar measurements.

  4. Data Assimilation in a Solar Dynamo Model Using Ensemble Kalman Filters: Sensitivity and Robustness in Reconstruction of Meridional Flow Speed

    NASA Astrophysics Data System (ADS)

    Dikpati, Mausumi; Anderson, Jeffrey L.; Mitra, Dhrubaditya

    2016-09-01

    We implement an Ensemble Kalman Filter procedure using the Data Assimilation Research Testbed for assimilating “synthetic” meridional flow-speed data in a Babcock-Leighton-type flux-transport solar dynamo model. By performing several “observing system simulation experiments,” we reconstruct time variation in meridional flow speed and analyze sensitivity and robustness of reconstruction. Using 192 ensemble members including 10 observations, each with 4% error, we find that flow speed is reconstructed best if observations of near-surface poloidal fields from low latitudes and tachocline toroidal fields from midlatitudes are assimilated. If observations include a mixture of poloidal and toroidal fields from different latitude locations, reconstruction is reasonably good for ≤slant 40 % error in low-latitude data, even if observational error in polar region data becomes 200%, but deteriorates when observational error increases in low- and midlatitude data. Solar polar region observations are known to contain larger errors than those in low latitudes; our forward operator (a flux-transport dynamo model here) can sustain larger errors in polar region data, but is more sensitive to errors in low-latitude data. An optimal reconstruction is obtained if an assimilation interval of 15 days is used; 10- and 20-day assimilation intervals also give reasonably good results. Assimilation intervals \\lt 5 days do not produce faithful reconstructions of flow speed, because the system requires a minimum time to develop dynamics to respond to flow variations. Reconstruction also deteriorates if an assimilation interval \\gt 45 days is used, because the system’s inherent memory interferes with its short-term dynamics during a substantially long run without updating.

  5. Filter assay technique and quench-flow experiments: examples of receptor-mediated transmembrane ion-exchange measured with membrane vesicles.

    PubMed

    Cash, D J; Subbarao, K; Bradbury, J R; Mayes, G M

    1991-09-01

    Modifications to a quench-flow apparatus are described which allow a rapid, in-line filter assay with immediate washing, in conditions to give minimum background. A design for an effluent spout is presented, which decelerates the liquid by a large factor, prevents splashes, limits the area of the filter exposed to the sample and allows an immediate wash over a larger area. A design for a filter assay funnel for general use is also presented. These devices feature minimal contact of the funnels with the filter disc. Examples are given in which in-line filtration was used to follow transmembrane ion flux in membrane vesicle preparations. In measurements of transmembrane flux with membrane vesicles and radioisotope the filter assay background can be resolved into three components. These are, (1) the uptake of radioactivity by the filter, (2) the radioactivity inside the vesicles not taking part in the specific measurement and (3) the occlusion of radioactivity in aggregated membrane particles on the filter. These different components depend on the conditions in different ways. Techniques for minimizing the background in filter assays are discussed. The importance of rapid filtration and immediate washing is demonstrated. The examples given illustrate that the function of the acetylcholine receptor from E. electricus is not affected by diisopropylfluorophosphate in the conditions used, and that added GABA is not removed from solution in a brain membrane preparation by the GABA uptake mechanisms in the short times of the experiments. PMID:1658108

  6. A method of adaptive wavelet filtering of the peripheral blood flow oscillations under stationary and non-stationary conditions.

    PubMed

    Tankanag, Arina V; Chemeris, Nikolay K

    2009-10-01

    The paper describes an original method for analysis of the peripheral blood flow oscillations measured with the laser Doppler flowmetry (LDF) technique. The method is based on the continuous wavelet transform and adaptive wavelet theory and applies an adaptive wavelet filtering to the LDF data. The method developed allows one to examine the dynamics of amplitude oscillations in a wide frequency range (from 0.007 to 2 Hz) and to process both stationary and non-stationary short (6 min) signals. The capabilities of the method have been demonstrated by analyzing LDF signals registered in the state of rest and upon humeral occlusion. The paper shows the main advantage of the method proposed, which is the significant reduction of 'border effects', as compared to the traditional wavelet analysis. It was found that the low-frequency amplitudes obtained by adaptive wavelets are significantly higher than those obtained by non-adaptive ones. The method suggested would be useful for the analysis of low-frequency components of the short-living transitional processes under the conditions of functional tests. The method of adaptive wavelet filtering can be used to process stationary and non-stationary biomedical signals (cardiograms, encephalograms, myograms, etc), as well as signals studied in the other fields of science and engineering.

  7. Performance of system consisting of vertical flow trickling filter and horizontal flow multi-soil-layering reactor for treatment of rural wastewater.

    PubMed

    Zhang, Yi; Cheng, Yan; Yang, Chunping; Luo, Wei; Zeng, Guangming; Lu, Li

    2015-10-01

    In order to improve nitrogen removal for rural wastewater, a novel two-stage hybrid system, consisting of a vertical flow trickling filter (VFTF) and a horizontal flow multi-soil-layering (HFMSL) bioreactor was developed. The performance of the apparatus was observed under various carbon-nitrogen ratios and water spraying frequencies separately. The maximum removal efficiency of total nitrogen (TN) for the hybrid system was 92.8% while the removal rates of CODCr, ammonium (NH4(+)-N), and total phosphorus (TP) were 94.1%, 96.1%, 92.0% respectively, and the corresponding effluent concentrations were 3.61, 21.20, 1.91, and 0.33 mg L(-1). The horizontal flow mode for MSL led the system to denitrifying satisfactorily as it ensured relatively long hydraulic retention time (HRT), ideal anoxic condition and adequate organic substrates supply. Also, higher water spraying frequency benefited intermittent feeding system for pollutants removal. Shock loading test indicated that the hybrid system could operate well even at hydraulic shock loadings. PMID:26151854

  8. Performance of system consisting of vertical flow trickling filter and horizontal flow multi-soil-layering reactor for treatment of rural wastewater.

    PubMed

    Zhang, Yi; Cheng, Yan; Yang, Chunping; Luo, Wei; Zeng, Guangming; Lu, Li

    2015-10-01

    In order to improve nitrogen removal for rural wastewater, a novel two-stage hybrid system, consisting of a vertical flow trickling filter (VFTF) and a horizontal flow multi-soil-layering (HFMSL) bioreactor was developed. The performance of the apparatus was observed under various carbon-nitrogen ratios and water spraying frequencies separately. The maximum removal efficiency of total nitrogen (TN) for the hybrid system was 92.8% while the removal rates of CODCr, ammonium (NH4(+)-N), and total phosphorus (TP) were 94.1%, 96.1%, 92.0% respectively, and the corresponding effluent concentrations were 3.61, 21.20, 1.91, and 0.33 mg L(-1). The horizontal flow mode for MSL led the system to denitrifying satisfactorily as it ensured relatively long hydraulic retention time (HRT), ideal anoxic condition and adequate organic substrates supply. Also, higher water spraying frequency benefited intermittent feeding system for pollutants removal. Shock loading test indicated that the hybrid system could operate well even at hydraulic shock loadings.

  9. Simulation of underresolved turbulent flows by adaptive filtering using the high order discontinuous Galerkin spectral element method

    NASA Astrophysics Data System (ADS)

    Flad, David; Beck, Andrea; Munz, Claus-Dieter

    2016-05-01

    Scale-resolving simulations of turbulent flows in complex domains demand accurate and efficient numerical schemes, as well as geometrical flexibility. For underresolved situations, the avoidance of aliasing errors is a strong demand for stability. For continuous and discontinuous Galerkin schemes, an effective way to prevent aliasing errors is to increase the quadrature precision of the projection operator to account for the non-linearity of the operands (polynomial dealiasing, overintegration). But this increases the computational costs extensively. In this work, we present a novel spatially and temporally adaptive dealiasing strategy by projection filtering. We show this to be more efficient for underresolved turbulence than the classical overintegration strategy. For this novel approach, we discuss the implementation strategy and the indicator details, show its accuracy and efficiency for a decaying homogeneous isotropic turbulence and the transitional Taylor-Green vortex and compare it to the original overintegration approach and a state of the art variational multi-scale eddy viscosity formulation.

  10. Performance Evaluation, Emulation, and Control of Cross-Flow Hydrokinetic Turbines

    NASA Astrophysics Data System (ADS)

    Cavagnaro, Robert J.

    Cross-flow hydrokinetic turbines are a promising option for effectively harvesting energy from fast-flowing streams or currents. This work describes the dynamics of such turbines, analyzes techniques used to scale turbine properties for prototyping, determines and demonstrates the limits of stability for cross-flow rotors, and discusses means and objectives of turbine control. Novel control strategies are under development to utilize low-speed operation (slower than at maximum power point) as a means of shedding power under rated conditions. However, operation in this regime may be unstable. An experiment designed to characterize the stability of a laboratory-scale cross-flow turbine operating near a critically low speed yields evidence that system stall (complete loss of ability to rotate) occurs due, in part, to interactions with turbulent decreases in flow speed. The turbine is capable of maintaining 'stable' operation at critical speed for short duration (typically less than 10 s), as described by exponential decay. The presence of accelerated 'bypass' flow around the rotor and decelerated 'induction' region directly upstream of the rotor, both predicted by linear momentum theory, are observed and quantified with particle image velocimetry (PIV) measurements conducted upstream of the turbine. Additionally, general agreement is seen between PIV inflow measurements and those obtained by an advection-corrected acoustic Doppler velocimeter (ADV) further upstream. Performance of a turbine at small (prototype) geometric scale may be prone to undesirable effects due to operation at low Reynolds number and in the presence of high channel blockage. Therefore, testing at larger scale, in open water is desirable. A cross-flow hydrokinetic turbine with a projected area (product of blade span and rotor diameter) of 0.7 m2 is evaluated in open-water tow trials at three inflow speeds ranging from 1.0 m/s to 2.1 m/s. Measurements of the inflow velocity, the rotor mechanical

  11. Insect-Inspired Self-Motion Estimation with Dense Flow Fields—An Adaptive Matched Filter Approach

    PubMed Central

    Strübbe, Simon; Stürzl, Wolfgang; Egelhaaf, Martin

    2015-01-01

    The control of self-motion is a basic, but complex task for both technical and biological systems. Various algorithms have been proposed that allow the estimation of self-motion from the optic flow on the eyes. We show that two apparently very different approaches to solve this task, one technically and one biologically inspired, can be transformed into each other under certain conditions. One estimator of self-motion is based on a matched filter approach; it has been developed to describe the function of motion sensitive cells in the fly brain. The other estimator, the Koenderink and van Doorn (KvD) algorithm, was derived analytically with a technical background. If the distances to the objects in the environment can be assumed to be known, the two estimators are linear and equivalent, but are expressed in different mathematical forms. However, for most situations it is unrealistic to assume that the distances are known. Therefore, the depth structure of the environment needs to be determined in parallel to the self-motion parameters and leads to a non-linear problem. It is shown that the standard least mean square approach that is used by the KvD algorithm leads to a biased estimator. We derive a modification of this algorithm in order to remove the bias and demonstrate its improved performance by means of numerical simulations. For self-motion estimation it is beneficial to have a spherical visual field, similar to many flying insects. We show that in this case the representation of the depth structure of the environment derived from the optic flow can be simplified. Based on this result, we develop an adaptive matched filter approach for systems with a nearly spherical visual field. Then only eight parameters about the environment have to be memorized and updated during self-motion. PMID:26308839

  12. Insect-Inspired Self-Motion Estimation with Dense Flow Fields--An Adaptive Matched Filter Approach.

    PubMed

    Strübbe, Simon; Stürzl, Wolfgang; Egelhaaf, Martin

    2015-01-01

    The control of self-motion is a basic, but complex task for both technical and biological systems. Various algorithms have been proposed that allow the estimation of self-motion from the optic flow on the eyes. We show that two apparently very different approaches to solve this task, one technically and one biologically inspired, can be transformed into each other under certain conditions. One estimator of self-motion is based on a matched filter approach; it has been developed to describe the function of motion sensitive cells in the fly brain. The other estimator, the Koenderink and van Doorn (KvD) algorithm, was derived analytically with a technical background. If the distances to the objects in the environment can be assumed to be known, the two estimators are linear and equivalent, but are expressed in different mathematical forms. However, for most situations it is unrealistic to assume that the distances are known. Therefore, the depth structure of the environment needs to be determined in parallel to the self-motion parameters and leads to a non-linear problem. It is shown that the standard least mean square approach that is used by the KvD algorithm leads to a biased estimator. We derive a modification of this algorithm in order to remove the bias and demonstrate its improved performance by means of numerical simulations. For self-motion estimation it is beneficial to have a spherical visual field, similar to many flying insects. We show that in this case the representation of the depth structure of the environment derived from the optic flow can be simplified. Based on this result, we develop an adaptive matched filter approach for systems with a nearly spherical visual field. Then only eight parameters about the environment have to be memorized and updated during self-motion.

  13. Blockage effects on the hydrodynamic performance of a marine cross-flow turbine.

    PubMed

    Consul, Claudio A; Willden, Richard H J; McIntosh, Simon C

    2013-02-28

    This paper explores the influence of blockage and free-surface deformation on the hydrodynamic performance of a generic marine cross-flow turbine. Flows through a three-bladed turbine with solidity 0.125 are simulated at field-test blade Reynolds numbers, O(10(5)-10(6)), for three different cross-stream blockages: 12.5, 25 and 50 per cent. Two representations of the free-surface boundary are considered: rigid lid and deformable free surface. Increasing the blockage is observed to lead to substantial increases in the power coefficient; the highest power coefficient computed is 1.23. Only small differences are observed between the two free-surface representations, with the deforming free-surface turbine out-performing the rigid lid turbine by 6.7 per cent in power at the highest blockage considered. This difference is attributed to the increase in effective blockage owing to the deformation of the free surface. Hydrodynamic efficiency, the ratio of useful power generated to overall power removed from the flow, is found to increase with blockage, which is consistent with the presence of a higher flow velocity through the core of the turbine at higher blockage ratios. Froude number is found to have little effect on thrust and power coefficients, but significant influence on surface elevation drop across the turbine.

  14. Experimental study on corrugated cross-flow air-cooled plate heat exchangers

    SciTech Connect

    Kim, Minsung; Baik, Young-Jin; Park, Seong-Ryong; Ra, Ho-Sang; Lim, Hyug

    2010-11-15

    Experimental study on cross-flow air-cooled plate heat exchangers (PHEs) was performed. The two prototype PHEs were manufactured in a stack of single-wave plates and double-wave plates in parallel. Cooling air flows through the PHEs in a crosswise direction against internal cooling water. The heat exchanger aims to substitute open-loop cooling towers with closed-loop water circulation, which guarantees cleanliness and compactness. In this study, the prototype PHEs were tested in a laboratory scale experiments. From the tests, double-wave PHE shows approximately 50% enhanced heat transfer performance compared to single-wave PHE. However, double-wave PHE costs 30% additional pressure drop. For commercialization, a wide channel design for air flow would be essential for reliable performance. (author)

  15. Investigation of Blade Angle of an Open Cross-Flow Runner

    NASA Astrophysics Data System (ADS)

    Katayama, Yusuke; Iio, Shouichiro; Veerapun, Salisa; Uchiyama, Tomomi

    2015-04-01

    The aim of this study was to develop a nano-hydraulic turbine utilizing drop structure in irrigation channels or industrial waterways. This study was focused on an open-type cross-flow turbine without any attached equipment for cost reduction and easy maintenance. In this study, the authors used an artificial indoor waterfall as lab model. Test runner which is a simple structure of 20 circular arc-shaped blades sandwiched by two circular plates was used The optimum inlet blade angle and the relationship between the power performance and the flow rate approaching theoretically and experimentally were investigated. As a result, the optimum inlet blade angle due to the flow rate was changed. Additionally, allocation rate of power output in 1st stage and 2nd stage is changed by the blade inlet angle.

  16. Property of reciprocity for stratified laminar flows in channels with arbitrarily shaped cross sections

    NASA Astrophysics Data System (ADS)

    Geshev, P. I.

    2015-05-01

    A stratified laminar flow of several fluids in a channels with an arbitrarily shaped cross section is considered. It is assumed that the hydrostatic problem of finding free boundaries between different fluids is solved and domains of motion of individual fluids are known. Under the assumption that the medium motion arises under the action of an applied pressure gradient and volume gravity forces (or forces of inertia), the property of reciprocity between the applied forces F j and the flows of different components Q i , which is manifested as symmetry of the matrix of the flow rate coefficients L ij ( Q i = L ij F j ), is proved in the general form. General symmetric solutions of the problem for a plane channel and a circular tube are presented. Formulas for the coefficient of increasing of the fluid flow rate owing to the presence of a near-wall layer of the gas are derived. It is shown that the flow rate of water in a partly filled channel may exceed the flow rate in a completely filled channel by more than an order of magnitude.

  17. Rigid porous filter

    DOEpatents

    Chiang, Ta-Kuan; Straub, Douglas L.; Dennis, Richard A.

    2000-01-01

    The present invention involves a porous rigid filter including a plurality of concentric filtration elements having internal flow passages and forming external flow passages there between. The present invention also involves a pressure vessel containing the filter for the removal of particulates from high pressure particulate containing gases, and further involves a method for using the filter to remove such particulates. The present filter has the advantage of requiring fewer filter elements due to the high surface area-to-volume ratio provided by the filter, requires a reduced pressure vessel size, and exhibits enhanced mechanical design properties, improved cleaning properties, configuration options, modularity and ease of fabrication.

  18. Research on sintering behavior and microwave dielectric property of (Mg0.95Ca0.05)TiO3 ceramics for cross coupling filter

    NASA Astrophysics Data System (ADS)

    Luo, Chunya; Ma, Zhichao; Hu, Laisheng; Hu, Mingzhe; Huang, Xiaomin

    2015-12-01

    The microwave dielectric properties of 0.95%MgTiO3-0.05%CaTiO3 (abbreviated as 95MCT hereafter) ceramics have been studied for application in dielectric cross coupling filters. ZnO and Nb2O5 were selected as liquid sintering aids to lower the sintering temperature and enhance the Qf value of 95MCT and simultaneously we varied the mole ratio of ZnO : Nb2O5 to tune the microwave dielectric properties of 95MCT. When the ZnO : Nb2O5 mole ratio was 1.5 and the co-doping content was 0.25 wt.%, the optimal sintering temperature of 95MCT ceramic could be lowered from 1400∘C to 1320∘C and the Qf value could be improved by about 7.7%. The optimal microwave dielectric properties obtained under this condition were Qf = 72730 GHz (6.8 GHz), ɛr = 20.29 and τf = -6.84ppm/∘C, which demonstrated great potential usage in ceramic industry. High values of Qf ceramic were used to design the dielectric cross coupling filter. The dielectric filter measured at 2.35 GHz exhibited a 6.7% bandwidth (insert loss > -3 dB) of center frequency.

  19. CROSS-ROLL FLOW FORMING OF ODS ALLOY HEAT EXCHANGER TUBES FOR HOOP CREEP ENHANCEMENT

    SciTech Connect

    Bimal K. Kad

    2005-06-27

    Mechanically alloyed oxide dispersion strengthened (ODS) Fe-Cr-Al alloy thin walled tubes and sheets, produced via powder processing and consolidation methodologies, are promising materials for eventual use at temperatures up to 1200 C in the power generation industry, far above the temperature capabilities of conventional alloys. Target end-uses range from gas turbine combustor liners to high aspect ratio (L/D) heat exchanger tubes. Grain boundary creep processes at service temperatures, particularly those acting in the hoop direction, are the dominant failure mechanisms for such components. The processed microstructure of ODS alloys consists of high aspect ratio grains aligned parallel to the tube axis, a result of dominant axial metal flow which aligns the dispersoid particles and other impurities in the longitudinal direction. The dispersion distribution is unaltered on a micro scale by recrystallization thermal treatments, but the high aspect ratio grain shape typically obtained limits transverse grain spacing and consequently the hoop creep response. Improving hoop creep in ODS-alloy components will require understanding and manipulating the factors that control the recrystallization behavior, and represents a critical materials design and development challenge that must be overcome in order to fully exploit the potential of ODS alloys. The objectives of this program are to (1) increase creep-strength at temperature in ODS-alloy tube and liner components by 100% via, (2) preferential cross-roll flow forming and grain/particle fibering in the critical hoop direction. Recent studies in cross-rolled ODS-alloy sheets (produced from flattened tubes) indicate that transverse creep is significantly enhanced via controlled transverse grain fibering, and similar improvements are expected for cross-rolled tubes. The research program outlined here is iterative in nature and is intended to systematically (i) prescribe extrusion consolidation methodologies via detailed

  20. The Effect of Vortex Generators on a Jet in a Cross-Flow

    NASA Technical Reports Server (NTRS)

    Zaman, K. B. M. Q.; Foss, J. K.

    1997-01-01

    The effect of vortex generators in the form of tabs on the penetration and spreading of a jet in a cross-flow has been studied experimentally. It is found that the tab has very little effect when placed on the leeward side, i.e., on the downstream edge of the jet nozzle relative to the free-stream flow. A study of the static pressure distribution reveals significantly lower pressures on the leeward side. Thus, when placed on that side the tab does not produce a "pressure hill" of sufficient magnitude that is the primary source of streamwise vorticity in the flow field over the tab. This qualitatively explains the ineffectiveness. In comparison, there is a significant effect on the flow field when the tab is placed on the windward side, The sense of vorticity generated by the tab in the latter configuration is opposite to that of the bound vortex pair that otherwise characterizes the flow. Thus, the strength of the bound vortex pair is diminished and the jet penetration is reduced.

  1. Constraints of nonresponding flows based on cross layers in the networks

    NASA Astrophysics Data System (ADS)

    Zhou, Zhi-Chao; Xiao, Yang; Wang, Dong

    2016-02-01

    In the active queue management (AQM) scheme, core routers cannot manage and constrain user datagram protocol (UDP) data flows by the sliding window control mechanism in the transport layer due to the nonresponsive nature of such traffic flows. However, the UDP traffics occupy a large part of the network service nowadays which brings a great challenge to the stability of the more and more complex networks. To solve the uncontrollable problem, this paper proposes a cross layers random early detection (CLRED) scheme, which can control the nonresponding UDP-like flows rate effectively when congestion occurs in the access point (AP). The CLRED makes use of the MAC frame acknowledgement (ACK) transmitting congestion information to the sources nodes and utilizes the back-off windows of the MAC layer throttling data rate. Consequently, the UDP-like flows data rate can be restrained timely by the sources nodes in order to alleviate congestion in the complex networks. The proposed CLRED can constrain the nonresponsive flows availably and make the communication expedite, so that the network can sustain stable. The simulation results of network simulator-2 (NS2) verify the proposed CLRED scheme.

  2. Experimental evaluation of sound produced by two cylinders in a cross flow in various configurations

    NASA Astrophysics Data System (ADS)

    Bilka, Michael; Kerrian, Peter; Morris, Scott

    2012-11-01

    Cylinders in a cross flow is a canonical test case that is considered representative of industrial fluid flow problems, such as heat exchangers and aircraft landing gear. The general configurations are cylinders in tandem, parallel or staggered, which lead to several interesting flow phenomena such as wake cavity/wake interaction effects (tandem), symmetric/asymmetric wake behavior (parallel) or wake interaction/coanda effects (staggered), depending on relative location of the cylinders. In many cases, it is important to not only understand the flow interaction between the cylinders but also the acoustic consequence of such configurations. However, information on the acoustical behavior based on these configurations is relatively small compared to that of the steady aerodynamic and flow interaction behavior. The present work investigates the acoustic spectral properties of these configurations in order to characterize the sound produced by cylinder proximity and wake effects. The spectra are measured using an acoustic beam-forming technique to identify the sources and remove spurious content from the spectra.

  3. Mechanisms of Flame Stabilization and Blowout in a Reacting Turbulent Hydrogen Jet in Cross-Flow

    SciTech Connect

    Kolla, H.; Grout, R. W.; Gruber, A.; Chen, J. H.

    2012-08-01

    The mechanisms contributing to flame stabilization and blowout in a nitrogen-diluted hydrogen transverse jet in a turbulent boundary layer cross-flow (JICF) are investigated using three-dimensional direct numerical simulation (DNS) with detailed chemistry. Non-reacting JICF DNS were performed to understand the relative magnitude and physical location of low velocity regions on the leeward side of the fuel jet where a flame can potentially anchor. As the injection angle is reduced from 90{sup o} to 70{sup o}, the low velocity region was found to diminish significantly, both in terms of physical extent and magnitude, and hence, its ability to provide favorable conditions for flame anchoring and stabilization are greatly reduced. In the reacting JICF DNS a stable flame is observed for 90{sup o} injection angle and, on average, the flame root is in the vicinity of low velocity magnitude and stoichiometric mixture. When the injection angle is smoothly transitioned to 75{sup o} a transient flame blowout is observed. Ensemble averaged quantities on the flame base reveal two phases of the blowout characterized by a kinematic imbalance between flame propagation speed and flow normal velocity. In the first phase dominant flow structures repeatedly draw the flame base closer to the jet centerline resulting in richer-than-stoichiometric mixtures and high velocity magnitudes. In the second phase, in spite of low velocity magnitudes and a return to stoichiometry, due to jet bending and flame alignment normal to the cross-flow, the flow velocity normal to the flame base increases dramatically perpetuating the blowout.

  4. Jet mixing into a heated cross flow in a cylindrical duct: Influence of geometry and flow variations

    NASA Technical Reports Server (NTRS)

    Hatch, M. S.; Sowa, W. A.; Samuelsen, G. S.; Holdeman, J. D.

    1992-01-01

    To examine the mixing characteristics of jets in an axi-symmetric can geometry, temperature measurements were obtained downstream of a row of cold jets injected into a heated cross stream. Parametric, non-reacting experiments were conducted to determine the influence of geometry and flow variations on mixing patterns in a cylindrical configuration. Results show that jet to mainstream momentum flux ratio and orifice geometry significantly impact the mixing characteristics of jets in a can geometry. For a fixed number of orifices, the coupling between momentum flux ratio and injector determines (1) the degree of jet penetration at the injection plane, and (2) the extent of circumferential mixing downstream of the injection plane. The results also show that, at a fixed momentum flux ratio, jet penetration decreases with (1) an increase in slanted slot aspect ratio, and (2) an increase in the angle of the slots with respect to the mainstream direction.

  5. Heat transfer in oscillating flows with sudden change in cross section

    NASA Technical Reports Server (NTRS)

    Ibrahim, Mounir; Hashim, Waqar; Tew, Roy C.; Dudenhoefer, James E.

    1992-01-01

    Oscillating fluid flow (zero mean) with heat transfer, between two parallel plates with a sudden change in cross section, was examined computationally. The flow was assumed to be laminar and incompressible with inflow velocity uniform over the channel cross section but varying sinusoidally with time. Over 30 different cases were examined; these cases cover wide ranges of Re sub max (187.5 to 30000), Va (1 to 350), expansion ratio (1:2, 1:4, 1:8, and 1:12) and A sub r (0.68 to 4). Three different geometric cases were considered (asymmetric expansion and/or contraction, symmetric expansion/contraction, and symmetric blunt body). The heat transfer cases were based on constant wall temperature at higher (heating) or lower (cooling) value than the inflow fluid temperature. As a result of the oscillating flow, the fluid undergoes sudden expansion in one half of the cycle and sudden contraction in the other half. One heating case is examined in detail, and conclusions are drawn from all the cases (documented in detail elsewhere). Instantaneous friction factors and heat transfer coefficients, for some ranges of Re sub max and Va, deviated substantially from those predicted with steady state correlations.

  6. Ultrasonic Cross-Correlation Flow Measurement: Theory, Noise Contamination Mechanisms, and a Noise Mitigation Technique

    SciTech Connect

    Jenkins, D.M.; Lysak, P.D.; Capone, D.E.; Brown, W.L.; Askari, V.

    2006-07-01

    Based on past experience with ultrasonic cross-correlation flow meters in power plant environments, the presence of spatially correlated noise due to pressure waves, vibration, or sources other than transport of turbulent eddies will cause a bias in the time delays measured by the meter. Several techniques were developed to detect the existence of such correlated noise and correct for its effect at plant conditions. An analytical and experimental investigation was performed to further understand the basic physics of the noise mechanisms. The dominant error mechanisms investigated in this work were speed of sound perturbations due to pressure fluctuations and beam path length changes due to wall vibration. An analytical model was formulated which estimates the signal level of the flow meter based on the turbulent velocity field. From this model, an estimate of the system noise which would cause contamination could be determined. A test at a water tunnel facility was performed in order to evaluate the noise mechanisms. During this test, measurements were taken with and without controlled noise sources. Pressure and acceleration measurements were used to evaluate a coherent noise removal technique developed to mitigate the impact of noise in the ultrasonic cross-correlation flow measurement. The coherent noise removal technique was shown to be effective in removing noise during the water tunnel test. (authors)

  7. Extensional flow of hyaluronic acid solutions in an optimized microfluidic cross-slot devicea

    PubMed Central

    Haward, S. J.; Jaishankar, A.; Oliveira, M. S. N.; Alves, M. A.; McKinley, G. H.

    2013-01-01

    We utilize a recently developed microfluidic device, the Optimized Shape Cross-slot Extensional Rheometer (OSCER), to study the elongational flow behavior and rheological properties of hyaluronic acid (HA) solutions representative of the synovial fluid (SF) found in the knee joint. The OSCER geometry is a stagnation point device that imposes a planar extensional flow with a homogenous extension rate over a significant length of the inlet and outlet channel axes. Due to the compressive nature of the flow generated along the inlet channels, and the planar elongational flow along the outlet channels, the flow field in the OSCER device can also be considered as representative of the flow field that arises between compressing articular cartilage layers of the knee joints during running or jumping movements. Full-field birefringence microscopy measurements demonstrate a high degree of localized macromolecular orientation along streamlines passing close to the stagnation point of the OSCER device, while micro-particle image velocimetry is used to quantify the flow kinematics. The stress-optical rule is used to assess the local extensional viscosity in the elongating fluid elements as a function of the measured deformation rate. The large limiting values of the dimensionless Trouton ratio, Tr ∼ O(50), demonstrate that these fluids are highly extensional-thickening, providing a clear mechanism for the load-dampening properties of SF. The results also indicate the potential for utilizing the OSCER in screening of physiological SF samples, which will lead to improved understanding of, and therapies for, disease progression in arthritis sufferers. PMID:24738010

  8. Extensional flow of hyaluronic acid solutions in an optimized microfluidic cross-slot device.

    PubMed

    Haward, S J; Jaishankar, A; Oliveira, M S N; Alves, M A; McKinley, G H

    2013-07-01

    We utilize a recently developed microfluidic device, the Optimized Shape Cross-slot Extensional Rheometer (OSCER), to study the elongational flow behavior and rheological properties of hyaluronic acid (HA) solutions representative of the synovial fluid (SF) found in the knee joint. The OSCER geometry is a stagnation point device that imposes a planar extensional flow with a homogenous extension rate over a significant length of the inlet and outlet channel axes. Due to the compressive nature of the flow generated along the inlet channels, and the planar elongational flow along the outlet channels, the flow field in the OSCER device can also be considered as representative of the flow field that arises between compressing articular cartilage layers of the knee joints during running or jumping movements. Full-field birefringence microscopy measurements demonstrate a high degree of localized macromolecular orientation along streamlines passing close to the stagnation point of the OSCER device, while micro-particle image velocimetry is used to quantify the flow kinematics. The stress-optical rule is used to assess the local extensional viscosity in the elongating fluid elements as a function of the measured deformation rate. The large limiting values of the dimensionless Trouton ratio, Tr ∼ O(50), demonstrate that these fluids are highly extensional-thickening, providing a clear mechanism for the load-dampening properties of SF. The results also indicate the potential for utilizing the OSCER in screening of physiological SF samples, which will lead to improved understanding of, and therapies for, disease progression in arthritis sufferers.

  9. Hydrologic filtering of fish life history strategies across the United States: implications for stream flow alteration

    SciTech Connect

    McManamay, Ryan A.; Frimpong, Emmanuel A.

    2015-01-01

    Lotic fish have developed life history strategies adapted to the natural variation in stream flow regimes. The natural timing, duration, and magnitude of flow events has contributed to the diversity, production, and composition of fish assemblages over time. Studies evaluating the role of hydrology in structuring fish assemblages have been more common at the local or regional scale with very few studies conducted at the continental scale. Furthermore, quantitative linkages between natural hydrologic patterns and fish assemblages are rarely used to make predictions of ecological consequences of hydrologic alterations. We ask two questions: (1) what is the relative role of hydrology in structuring fish assemblages at large scales? and (2) can relationships between fish assemblages and natural hydrology be utilized to predict fish assemblage responses to hydrologic disturbance? We developed models to relate fish life histories and reproductive strategies to landscape and hydrologic variables separately and then combined. Models were then used to predict the ecological consequences of altered hydrology due to dam regulation. Although hydrology plays a considerable role in structuring fish assemblages, the performance of models using only hydrologic variables was lower than that of models constructed using landscape variables. Isolating the relative importance of hydrology in structuring fish assemblages at the continental scale is difficult since hydrology is interrelated to many landscape factors. By applying models to dam-regulated hydrologic data, we observed some consistent predicted responses in fish life history strategies and modes of reproduction. In agreement with existing literature, equilibrium strategists are predicted to increase following dam regulation, whereas opportunistic and periodic species are predicted to decrease. In addition, dam regulation favors the selection of reproductive strategies with extended spawning seasons and preference for stable

  10. Hydrologic filtering of fish life history strategies across the United States: implications for stream flow alteration

    DOE PAGESBeta

    McManamay, Ryan A.; Frimpong, Emmanuel A.

    2015-01-01

    Lotic fish have developed life history strategies adapted to the natural variation in stream flow regimes. The natural timing, duration, and magnitude of flow events has contributed to the diversity, production, and composition of fish assemblages over time. Studies evaluating the role of hydrology in structuring fish assemblages have been more common at the local or regional scale with very few studies conducted at the continental scale. Furthermore, quantitative linkages between natural hydrologic patterns and fish assemblages are rarely used to make predictions of ecological consequences of hydrologic alterations. We ask two questions: (1) what is the relative role ofmore » hydrology in structuring fish assemblages at large scales? and (2) can relationships between fish assemblages and natural hydrology be utilized to predict fish assemblage responses to hydrologic disturbance? We developed models to relate fish life histories and reproductive strategies to landscape and hydrologic variables separately and then combined. Models were then used to predict the ecological consequences of altered hydrology due to dam regulation. Although hydrology plays a considerable role in structuring fish assemblages, the performance of models using only hydrologic variables was lower than that of models constructed using landscape variables. Isolating the relative importance of hydrology in structuring fish assemblages at the continental scale is difficult since hydrology is interrelated to many landscape factors. By applying models to dam-regulated hydrologic data, we observed some consistent predicted responses in fish life history strategies and modes of reproduction. In agreement with existing literature, equilibrium strategists are predicted to increase following dam regulation, whereas opportunistic and periodic species are predicted to decrease. In addition, dam regulation favors the selection of reproductive strategies with extended spawning seasons and preference for

  11. Determination of filter-cake thicknesses from on-line flow measurements and gas/particle transport modeling

    SciTech Connect

    Smith, D.H.; Powell, V.; Ibrahim, E.; Ferer, M.; Ahmadi, G.

    1996-12-31

    The use of cylindrical candle filters to remove fine ({approx}0.005 mm) particles from hot ({approx}500- 900{degrees}C) gas streams currently is being developed for applications in advanced pressurized fluidized bed combustion (PFBC) and integrated gasification combined cycle (IGCC) technologies. Successfully deployed with hot-gas filtration, PFBC and IGCC technologies will allow the conversion of coal to electrical energy by direct passage of the filtered gases into non-ruggedized turbines and thus provide substantially greater conversion efficiencies with reduced environmental impacts. In the usual approach, one or more clusters of candle filters are suspended from a tubesheet in a pressurized (P {approx_lt}1 MPa) vessel into which hot gases and suspended particles enter, the gases pass through the walls of the cylindrical filters, and the filtered particles form a cake on the outside of each filter. The cake is then removed periodically by a backpulse of compressed air from inside the filter, which passes through the filter wall and filter cake. In various development or demonstration systems the thickness of the filter cake has proved to be an important, but unknown, process parameter. This paper describes a physical model for cake and pressure buildups between cleaning backpulses, and for longer term buildups of the ``baseline`` pressure drop, as caused by incomplete filter cleaning and/or re-entrainment. When combined with operating data and laboratory measurements of the cake porosity, the model may be used to calculate the (average) filter permeability, the filter-cake thickness and permeability, and the fraction of filter-cake left on the filter by the cleaning backpulse or re-entrained after the backpulse. When used for a variety of operating conditions (e.g., different coals, sorbents, temperatures, etc.), the model eventually may provide useful information on how the filter-cake properties depend on the various operating parameters.

  12. A cross-disciplinary understanding of incipient motion for effective environmental flow setting

    NASA Astrophysics Data System (ADS)

    Neverman, Andrew; Fuller, Ian; Death, Russell; Procter, Jon; Singh, Ranvir

    2016-04-01

    Environmental flow setting as a tool for maintaining ecological health in rivers has been a focus of debate for many years. Environmental flow setting often involves the establishment of base flow levels below impoundment structures as well as setting flushing flows in order to control excess periphyton accrual and sedimentation. The role of bedload transport and substrate stability is recognised as an integral part of effectively managing benthic communities, but environmental flow regulations often do not focus on managing sediment processes. Environmental flows which fail to scour periphyton have been attributed to increased biomass accumulation through increasing nutrient supply to periphyton mats. It may therefore be more effective to establish environmental flow models based on incipient motion thresholds. The aim of these models would be to establish target near-bed velocities as opposed to discharges. Establishment of such models requires an accurate understanding of the threshold conditions for incipient motion. Despite decades of incipient motion studies scientists are unable to consistently and accurately predict bedload transport in natural channels. Incipient motion results from a complex set of geomorphic, hydrologic, and ecological interactions operating over a range of spatial and temporal scales. Direct measurement of these processes can be difficult and time consuming, and has been restricted by a lack of suitable high spatio-temporal resolution methods in the past. This paper presents a cross-disciplinary approach to the study of incipient motion to develop effective environmental flow targets. Recent developments in remote sensing and 3D point cloud analysis are used to characterise substrate surfaces. Groundwater head pressures are measured during floods to examine changes in threshold velocities under different seepage conditions. The onset of bedload transport is recorded using impact plate sensors to relate transport initiation to near

  13. A Model for the Vortex Pair Associated with a Jet in a Cross Flow

    NASA Technical Reports Server (NTRS)

    Sellers, William L.

    1975-01-01

    A model is presented for the contrarotating vortex pair that is formed by a round, turbulent, subsonic jet directed normally into a uniform, subsonic cross flow. The model consists of a set of algebraic equations that describe the properties of the vortex pair as a function of their location in the jet plume. The parameters of the model are physical characteristics of the vortices such as the vortex strength, spacing, and core size. These parameters are determined by velocity measurements at selective points in the jet plume.

  14. Methods and systems for Raman and optical cross-interrogation in flow-through silicon membranes

    SciTech Connect

    Bond, Tiziana C.; Letant, Sonia E.

    2014-09-09

    Cross-interrogating photonic detection systems and methods are shown. A flow through photonic crystal membrane with a surface enhanced Raman scattering (SERS) substrate is provided with pores which are distributed along multiple regions. The pores of one region have walls to which a first type of target specific anchor can be attached, while pores of another region have walls to which a second type of target specific anchor can be attached. An optical arrangement out-of-plane to the SERS substrate is also provided for enhanced sensitivity and identification of target organisms.

  15. A fitness-driven cross-diffusion system from population dynamics as a gradient flow

    NASA Astrophysics Data System (ADS)

    Kondratyev, Stanislav; Monsaingeon, Léonard; Vorotnikov, Dmitry

    2016-09-01

    We consider a fitness-driven model of dispersal of N interacting populations, which was previously studied merely in the case N = 1. Based on some optimal transport distance recently introduced, we identify the model as a gradient flow in the metric space of Radon measures. We prove existence of global non-negative weak solutions to the corresponding system of parabolic PDEs, which involves degenerate cross-diffusion. Under some additional hypotheses and using a new multicomponent Poincaré-Beckner functional inequality, we show that the solutions converge exponentially to an ideal free distribution in the long time regime.

  16. Cross-correlation video recording of gas-vapor-droplet two-phase flows

    NASA Astrophysics Data System (ADS)

    Volkov, Roman S.; Vysokomornaya, Olga V.; Zhdanova, Alyona O.; Strizhak, Pavel A.

    2015-01-01

    The experimental investigations of gas-vapor-droplet two-phase flow formation during single water droplets and their aggregate motion through high-temperature (more than 1000 K) combustion products have been conducted with usage of cross-correlation measuring facility and optical methods of "tracer" visualization ("Particle Image Velocimetry" and "Interferometric Particle Imaging"). Modes of droplet motion in high-temperature gases area have been established. It has been determined the influence of the main droplet (sizes, composition, temperature, dispersability, form, velocity) and gas (temperature and velocity) characteristics on parameters of forming gas-vapor-droplet mixtures. The main elements of advanced firefighting technologies with the usage of time and space apportioned polydisperse composition water droplet flows have been formulated. Physical and predictive mathematical models have been developed to determine the basic parameters of equipment which is necessary for operation with these technology usage.

  17. Continuous Processing of Active Pharmaceutical Ingredients Suspensions via Dynamic Cross-Flow Filtration.

    PubMed

    Gursch, Johannes; Hohl, Roland; Toschkoff, Gregor; Dujmovic, Diana; Brozio, Jörg; Krumme, Markus; Rasenack, Norbert; Khinast, Johannes

    2015-10-01

    Over the last years, continuous manufacturing has created significant interest in the pharmaceutical industry. Continuous filtration at low flow rates and high solid loadings poses, however, a significant challenge. A commercially available, continuously operating, dynamic cross-flow filtration device (CFF) is tested and characterized. It is shown that the CFF is a highly suitable technology for continuous filtration. For all tested model active pharmaceutical ingredients, a material-specific strictly linear relationship between feed and permeate rate is identified. Moreover, for each tested substance, a constant concentration factor is reached. A one-parameter model based on a linear equation is suitable to fully describe the CFF filtration performance. This rather unexpected finding and the concentration polarization layer buildup is analyzed and a basic model to describe the observed filtration behavior is developed.

  18. Penetration Characteristics of Air, Carbon Dioxide and Helium Transverse Sonic Jets in Mach 5 Cross Flow

    PubMed Central

    Erdem, Erinc; Kontis, Konstantinos; Saravanan, Selvaraj

    2014-01-01

    An experimental investigation of sonic air, CO2 and Helium transverse jets in Mach 5 cross flow was carried out over a flat plate. The jet to freestream momentum flux ratio, J, was kept the same for all gases. The unsteady flow topology was examined using high speed schlieren visualisation and PIV. Schlieren visualisation provided information regarding oscillating jet shear layer structures and bow shock, Mach disc and barrel shocks. Two-component PIV measurements at the centreline, provided information regarding jet penetration trajectories. Barrel shocks and Mach disc forming the jet boundary were visualised/quantified also jet penetration boundaries were determined. Even though J is kept the same for all gases, the penetration patterns were found to be remarkably different both at the nearfield and the farfield. Air and CO2 jet resulted similar nearfield and farfield penetration pattern whereas Helium jet spread minimal in the nearfield. PMID:25494348

  19. Anomalous magnetosheath dynamics: magnetosheath crossings by spacecraft in few minutes and flow balancing by plasma jets

    NASA Astrophysics Data System (ADS)

    Savin, Sergey; Amata, Ermanno; Zelenyi, Lev; Budaev, Viacheslav; Sibeck, David; Borodkova, Natalia; Angelopoulos, Vassilis; Rauch, Jean-Lous; Panov, Eugene; Blecki, Jan

    2010-05-01

    Multipoint spacecraft measurements in the magnetosheath by Cluster, Double Star, THEMIS and Interball demonstrate that the spacecraft could cross the magnetosheath in few minutes, while usually it takes hours. We discuss this anomalous magnetosheath dynamics in view of both of solar wind and intrinsic magnetosheath features, including the magnetosheath plasma flow stratification. The stratified magnetosheath flows can carry a substantial part of the total magnetosheath flux, being an alternative to the uniform magnetosheath state. On the basis of data presented, we display an evidence for the superdiffusion regime in the region close to the magnetopause, which surprisingly co-exists with the evident separation of the moving plasmas by a turbulent transport barrier. We present the transport barrier properties and value in the context of the common physics aspects including fusion devices and future multi-point missions.

  20. An experimental study of the flow field surrounding a subsonic jet in a cross flow. M.S. Thesis

    NASA Technical Reports Server (NTRS)

    Dennis, Robert Foster

    1993-01-01

    An experimental investigation of the flow interaction of a 5.08 cm (2.00 in.) diameter round subsonic jet exhausting perpendicularly to a flat plate in a subsonic cross flow was conducted in the NASA Ames 7x1O ft. Wind Tunnel Number One. Flat plate surface pressures were measured at 400 locations in a 30.48 cm (12.0 in.) concentric circular array surrounding the jet exit. Results from these measurements are provided in tabular and graphical form for jet-to-crossflow velocity ratios ranging from 4 to 12, and for jet exit Mach numbers ranging from 0.50 to 0.93. Laser doppler velocimeter (LDV) three component velocity measurements were made in selected regions in the developed jet plume and near the flat plate surface, at a jet Mach number of 0.50 and jet-to-crossflow velocity ratios of 6 and 8. The results of both pressure and LDV measurements are compared with the results of previous experiments. In addition, pictures of the jet plume shape at jet velocity ratios ranging from 4 to 12 were obtained using schleiren photography. The LDV measurements are consistent with previous work, but more extensive measurements will be necessary to provide a detailed picture of the flow field. The surface pressure results compare closely with previous work and provide a useful characterization of jet induced surface pressures. The results demonstrate the primary influence of jet velocity ratio and the secondary influence of jet Mach number in determining such surface pressures.

  1. Axisymmetric electrostatic magnetohydrodynamic oscillations in tokamaks with general cross-sections and toroidal flow

    NASA Astrophysics Data System (ADS)

    Chu, M. S.; Guo, Wenfeng

    2016-06-01

    The frequency spectrum and mode structure of axisymmetric electrostatic oscillations [the zonal flow (ZF), sound waves (SW), geodesic acoustic modes (GAM), and electrostatic mean flows (EMF)] in tokamaks with general cross-sections and toroidal flows are studied analytically using the electrostatic approximation for magnetohydrodynamic modes. These modes constitute the "electrostatic continua." Starting from the energy principle for a tokamak plasma with toroidal rotation, we showed that these modes are completely stable. The ZF, the SW, and the EMF could all be viewed as special cases of the general GAM. The Euler equations for the general GAM are obtained and are solved analytically for both the low and high range of Mach numbers. The solution consists of the usual countable infinite set of eigen-modes with discrete eigen-frequencies, and two modes with lower frequencies. The countable infinite set is identified with the regular GAM. The lower frequency mode, which is also divergence free as the plasma rotation tends to zero, is identified as the ZF. The other lower (zero) frequency mode is a pure geodesic E×B flow and not divergence free is identified as the EMF. The frequency of the EMF is shown to be exactly 0 independent of plasma cross-section or its flow Mach number. We also show that in general, sound waves with no geodesic components are (almost) completely lost in tokamaks with a general cross-sectional shape. The exception is the special case of strict up-down symmetry. In this case, half of the GAMs would have no geodesic displacements. They are identified as the SW. Present day tokamaks, although not strictly up-down symmetric, usually are only slightly up-down asymmetric. They are expected to share the property with the up-down symmetric tokamak in that half of the GAMs would be more sound wave-like, i.e., have much weaker coupling to the geodesic components than the other half of non-sound-wave-like modes with stronger coupling to the geodesic

  2. Blown Away: The Shedding and Oscillation of Sessile Drops by Cross Flowing Air

    NASA Astrophysics Data System (ADS)

    Milne, Andrew James Barnabas

    For drops sessile on a solid surface, cross flowing air can drive drop oscillation or shedding, based on the balance and interaction of aerodynamic drag force (based on drop size/shape and air speed) and adhesion/capillary forces (based on surface tension and drop size/shape). Better understanding of the above has applications to, e.g., fuel cell flooding, airfoil icing, and visibility in rain. To understand the basic physics, experiments studying individual sessile drops in a low speed wind tunnel were performed in this thesis. Analysis of high speed video gave time resolved profiles and airspeed for shedding. Testing 0.5 mul to 100 mul drops of water and hexadecane on poly(methyl methacrylate) PMMA, Teflon, and a superhydrophobic surface (SHS) yielded a master curve describing critical airspeed for shedding for water drops on all surface tested. This curve predicts behavior for new surfaces, and explains experimental results published previously. It also indicates that the higher contact angle leads to easier shedding due to decreased adhesion and increased drag. Developing a novel floating element differential drag sensor gave the first measurements of the microNewton drag force experienced by drops. Forces magnitude is comparable to gravitational shedding from a tilted plate and to simplified models for drop adhesion, with deviations that suggest effects due to the air flow. Fluid properties are seen to have little effect on drag versus airspeed, and decreased adhesion is seen to be more important than increased drag for easing shedding. The relation between drag coefficient and Reynolds number increases slightly with liquid-solid contact angle, and with drop volume. Results suggest that the drop experiences increased drag compared to similarly shaped solid bodies due to drop oscillations aeroelasticly coupling into the otherwise laminar flow. The bulk and surface oscillations of sessile drops in cross flow was also studied, using a full profile analysis

  3. Flow-induced oscillations of a prism with triangular cross-section placed in water

    NASA Astrophysics Data System (ADS)

    Carlson, Daniel; Seyed-Aghazadeh, Banafsheh; Modarres-Sadeghi, Yahya

    2015-11-01

    Flow-induced oscillations of a prism with a triangular cross-section was studied experimentally. The cylinder had one-degree-of-freedom to oscillate in the crossflow direction. The response of the cylinder in terms of the amplitudes of oscillations as well as the flow forces were studied at varying angles of attack in the range of α = 0° -60° and a reduced velocity range of U* =4-22. Depending on the angle of attack and the reduced velocity, the cylinder experienced either VIV or galloping. For small angles of attack of α<30°, the cylinder did not oscillate while for larger angles of α = 30° and 35°, the cylinder underwent VIV in a range of reduced velocities (U* =7-14.5) and galloping at higher reduced velocities (U* =19.5-22). The conducted dye flow visualization as well as the measured flow forces confirmed the existence of lock-in as well as galloping-type response. For larger angles of attack of α>35°, the amplitude of oscillations increased monotonically with increasing reduced velocity and the cylinder underwent galloping. Several different vortex shedding patterns were observed in the wake of the cylinder at different angles of attack and flow velocities. New, high-frequency shedding patterns with their corresponding high harmonic shedding frequencies in the flow force FFTs were observed in the regions where galloping occurred. This work is partially supported by the NSF-sponsored IGERT: Offshore Wind Energy Engineering, Environmental Science, and Policy (Grant Number 1068864).

  4. Scaling Law for Cross-stream Diffusion in Microchannels under Combined Electroosmotic and Pressure Driven Flow.

    PubMed

    Song, Hongjun; Wang, Yi; Pant, Kapil

    2013-01-01

    This paper presents an analytical study of the cross-stream diffusion of an analyte in a rectangular microchannel under combined electroosmotic flow (EOF) and pressure driven flow to investigate the heterogeneous transport behavior and spatially-dependent diffusion scaling law. An analytical model capable of accurately describing 3D steady-state convection-diffusion in microchannels with arbitrary aspect ratios is developed based on the assumption of the thin Electric Double Layer (EDL). The model is verified against high-fidelity numerical simulation in terms of flow velocity and analyte concentration profiles with excellent agreement (<0.5% relative error). An extensive parametric analysis is then undertaken to interrogate the effect of the combined flow velocity field on the transport behavior in both the positive pressure gradient (PPG) and negative pressure gradient (NPG) cases. For the first time, the evolution from the spindle-shaped concentration profile in the PPG case, via the stripe-shaped profile (pure EOF), and finally to the butterfly-shaped profile in the PPG case is obtained using the analytical model along with a quantitative depiction of the spatially-dependent diffusion layer thickness and scaling law across a wide range of the parameter space.

  5. Scaling Law for Cross-stream Diffusion in Microchannels under Combined Electroosmotic and Pressure Driven Flow.

    PubMed

    Song, Hongjun; Wang, Yi; Pant, Kapil

    2013-01-01

    This paper presents an analytical study of the cross-stream diffusion of an analyte in a rectangular microchannel under combined electroosmotic flow (EOF) and pressure driven flow to investigate the heterogeneous transport behavior and spatially-dependent diffusion scaling law. An analytical model capable of accurately describing 3D steady-state convection-diffusion in microchannels with arbitrary aspect ratios is developed based on the assumption of the thin Electric Double Layer (EDL). The model is verified against high-fidelity numerical simulation in terms of flow velocity and analyte concentration profiles with excellent agreement (<0.5% relative error). An extensive parametric analysis is then undertaken to interrogate the effect of the combined flow velocity field on the transport behavior in both the positive pressure gradient (PPG) and negative pressure gradient (NPG) cases. For the first time, the evolution from the spindle-shaped concentration profile in the PPG case, via the stripe-shaped profile (pure EOF), and finally to the butterfly-shaped profile in the PPG case is obtained using the analytical model along with a quantitative depiction of the spatially-dependent diffusion layer thickness and scaling law across a wide range of the parameter space. PMID:23554584

  6. Groundwater Budget Analysis of Cross Formational Flow: Hueco Bolson (Texas and Chihuahua)

    NASA Astrophysics Data System (ADS)

    Hutchison, W. R.

    2005-12-01

    Groundwater from the Hueco Bolson supplies the majority of municipal water in El Paso, Texas and Ciudad Juarez, Chihuahua, the largest international border community in the world. For over 100 years, water managers and researchers have been developing an understanding of Hueco Bolson groundwater occurrence and movement, and the interaction between surface water and groundwater. Since 2001, isotopic studies of groundwater chemistry on both sides of the border have provided valuable insights into the occurrence of groundwater and its historic movement. Numerical groundwater flow models of the area have been developed and used since the 1970s. The results of the most recent model were used to develop a detailed analysis of the groundwater inflows, outflows and storage change of the entire area and subregions of the model domain from 1903 to 2002. These detailed groundwater budgets were used to quantify temporal and spatial flow changes that resulted from groundwater pumping: induced inflow of surface water, decreased natural outflows, and storage declines. In addition, the detailed groundwater budgets were used to quantify the changes in cross formational flow between the Rio Grande Alluvium and the Hueco Bolson, as well as the changes in vertical flow within the Hueco Bolson. The groundwater budget results are consistent with the results of the isotopic analyses, providing a much needed confirmation of the overall conceptual model of the numerical model. In addition, the groundwater budgets have provided information that has been useful in further interpreting the results of the isotopic analyses.

  7. Cross-correlation of instantaneous phase increments in pressure-flow fluctuations: Applications to cerebral autoregulation

    PubMed Central

    Chen, Zhi; Hu, Kun; Stanley, H. Eugene; Novak, Vera; Ivanov, Plamen Ch.

    2007-01-01

    We investigate the relationship between the blood flow velocities (BFV) in the middle cerebral arteries and beat-to-beat blood pressure (BP) recorded from a finger in healthy and post-stroke subjects during the quasisteady state after perturbation for four different physiologic conditions: supine rest, head-up tilt, hyperventilation, and CO2 rebreathing in upright position. To evaluate whether instantaneous BP changes in the steady state are coupled with instantaneous changes in the BFV, we compare dynamical patterns in the instantaneous phases of these signals, obtained from the Hilbert transform, as a function of time. We find that in post-stroke subjects the instantaneous phase increments of BP and BFV exhibit well-pronounced patterns that remain stable in time for all four physiologic conditions, while in healthy subjects these patterns are different, less pronounced, and more variable. We propose an approach based on the cross-correlation of the instantaneous phase increments to quantify the coupling between BP and BFV signals. We find that the maximum correlation strength is different for the two groups and for the different conditions. For healthy subjects the amplitude of the cross-correlation between the instantaneous phase increments of BP and BFV is small and attenuates within 3−5 heartbeats. In contrast, for post-stroke subjects, this amplitude is significantly larger and cross-correlations persist up to 20 heartbeats. Further, we show that the instantaneous phase increments of BP and BFV are cross-correlated even within a single heartbeat cycle. We compare the results of our approach with three complementary methods: direct BP-BFV cross-correlation, transfer function analysis, and phase synchronization analysis. Our findings provide insight into the mechanism of cerebral vascular control in healthy subjects, suggesting that this control mechanism may involve rapid adjustments (within a heartbeat) of the cerebral vessels, so that BFV remains steady in

  8. Cross-Roll Flow Forming of ODS Alloy Heat Exchanger Tubes For Hoop Creep Enhancement

    SciTech Connect

    Bimal K. Kad

    2006-09-30

    Mechanically alloyed oxide dispersion strengthened (ODS) Fe-Cr-Al alloy thin walled tubes and sheets, produced via powder processing and consolidation methodologies, are promising materials for eventual use at temperatures up to 1200 C in the power generation industry, far above the temperature capabilities of conventional alloys. Target end-uses range from gas turbine combustor liners to high aspect ratio (L/D) heat exchanger tubes. Grain boundary creep processes at service temperatures, particularly those acting in the hoop direction, are the dominant failure mechanisms for such components. The processed microstructure of ODS alloys consists of high aspect ratio grains aligned parallel to the tube axis, a result of dominant axial metal flow which aligns the dispersoid particles and other impurities in the longitudinal direction. The dispersion distribution is unaltered on a micro scale by recrystallization thermal treatments, but the high aspect ratio grain shape typically obtained limits transverse grain spacing and consequently the hoop creep response. Improving hoop creep in ODS-alloy components will require understanding and manipulating the factors that control the recrystallization behavior, and represents a critical materials design and development challenge that must be overcome in order to fully exploit the potential of ODS alloys. The objectives of this program are to (1) increase creep-strength at temperature in ODS-alloy tube and liner components by 100% via, (2) preferential cross-roll flow forming and grain/particle fibering in the critical hoop direction. The research program outlined here is iterative in nature and is intended to systematically (a) examine and identify post-extrusion forming methodologies to create hoop strengthened tubes, which will be (b) evaluated at ''in-service'' loads at service temperatures and environments. In this 12th quarter of performance, program activities are concluded for Task 2 and continuing for Tasks 3, 4 and

  9. Air filtration in the free molecular flow regime: a review of high-efficiency particulate air filters based on carbon nanotubes.

    PubMed

    Li, Peng; Wang, Chunya; Zhang, Yingying; Wei, Fei

    2014-11-01

    Air filtration in the free molecular flow (FMF) regime is important and challenging because a higher filtration efficiency and lower pressure drop are obtained when the fiber diameter is smaller than the gas mean free path in the FMF regime. In previous studies, FMF conditions have been obtained by increasing the gas mean free path through reducing the pressure and increasing the temperature. In the case of carbon nanotubes (CNTs) with nanoscale diameters, it is possible to filtrate in the FMF regime under normal conditions. This paper reviews recent progress in theoretical and experimental studies of air filtration in the FMF regime. Typical structure models of high-efficiency particulate (HEPA) air filters based on CNTs are introduced. The pressure drop in air filters operated in the FMF regime is less than that predicted by the conventional air filtration theory. The thinnest HEPA filters fabricated from single-walled CNT films have an extremely low pressure drop. CNT air filters with a gradient nanostructure are shown to give a much better filtration performance in dynamic filtration. CNT air filters with a hierarchical structure and an agglomerated CNT fluidized bed air filter are also introduced. Finally, the challenges and opportunities for the application of CNTs in air filtration are discussed.

  10. Air filtration in the free molecular flow regime: a review of high-efficiency particulate air filters based on carbon nanotubes.

    PubMed

    Li, Peng; Wang, Chunya; Zhang, Yingying; Wei, Fei

    2014-11-01

    Air filtration in the free molecular flow (FMF) regime is important and challenging because a higher filtration efficiency and lower pressure drop are obtained when the fiber diameter is smaller than the gas mean free path in the FMF regime. In previous studies, FMF conditions have been obtained by increasing the gas mean free path through reducing the pressure and increasing the temperature. In the case of carbon nanotubes (CNTs) with nanoscale diameters, it is possible to filtrate in the FMF regime under normal conditions. This paper reviews recent progress in theoretical and experimental studies of air filtration in the FMF regime. Typical structure models of high-efficiency particulate (HEPA) air filters based on CNTs are introduced. The pressure drop in air filters operated in the FMF regime is less than that predicted by the conventional air filtration theory. The thinnest HEPA filters fabricated from single-walled CNT films have an extremely low pressure drop. CNT air filters with a gradient nanostructure are shown to give a much better filtration performance in dynamic filtration. CNT air filters with a hierarchical structure and an agglomerated CNT fluidized bed air filter are also introduced. Finally, the challenges and opportunities for the application of CNTs in air filtration are discussed. PMID:25288476

  11. Concentration polarization of interacting solute particles in cross-flow membrane filtration

    SciTech Connect

    Bhattacharjee, S.; Kim, A.S.; Elimelech, M.

    1999-04-01

    A theoretical approach for predicting the influence of interparticle interactions on concentration polarization and the ensuing permeate flux decline during cross-flow membrane filtration of charged solute particles is presented. The Ornstein-Zernike integral equation is solved using appropriate closures corresponding to hard-spherical and long-range solute-solute interactions to predict the radial distribution function of the solute particles in a concentrated solution (dispersion). Two properties of the solution, namely the osmotic pressure and the diffusion coefficient, are determined on the basis of the radial distribution function at different solute concentrations. Incorporation of the concentration dependence of these two properties in the concentration polarization model comprising the convective-diffusion equation and the osmotic-pressure governed permeate flux equation leads to the coupled prediction of the solute concentration profile and the local permeate flux. The approach leads to a direct quantitative incorporation of solute-solute interactions in the framework of a standard theory of concentration polarization. The developed model is used to study the effects of ionic strength and electrostatic potential on the variations of solute diffusivity and osmotic pressure. Finally, the combined influence of these two properties on the permeate flux decline behavior during cross-flow membrane filtration of charged solute particles is predicted.

  12. Liquid-metal pin-fin pressure drop by correlation in cross flow

    SciTech Connect

    Wang, Zhibi; Kuzay, T.M.; Assoufid, L.

    1994-08-01

    The pin-fin configuration is widely used as a heat transfer enhancement method in high-heat-flux applications. Recently, the pin-fin design with liquid-metal coolant was also applied to synchrotron-radiation beamline devices. This paper investigates the pressure drop in a pin-post design beamline mirror with liquid gallium as the coolant. Because the pin-post configuration is a relatively new concept, information in literature about pin-post mirrors or crystals is rare, and information about the pressure drop in pin-post mirrors with liquid metal as the coolant is even more sparse. Due to this the authors considered the cross flow in cylinder-array geometry, which is very similar to that of the pin-post, to examine the pressure drop correlation with liquid metals over pin fins. The cross flow of fluid with various fluid characteristics or properties through a tube bank was studied so that the results can be scaled to the pin-fin geometry with liquid metal as the coolant. Study lead to two major variables to influence the pressure drop: fluid properties, viscosity and density, and the relative length of the posts. Correlation of the pressure drop between long and short posts and the prediction of the pressure drop of liquid metal in the pin-post mirror and comparison with an existing experiment are addressed.

  13. Reynolds number effects on the performance and near-wake of a cross-flow turbine

    NASA Astrophysics Data System (ADS)

    Bachant, Peter; Wosnik, Martin

    2013-11-01

    To design wind or marine hydrokinetic (MHK) turbine farms with high efficiency, interactions between turbine wakes must be accurately predicted. However, to date numerical models predicting detailed wake properties of cross-flow (or vertical-axis) turbines have been validated with experimental data taken at Reynolds numbers significantly lower than those of full scale devices, casting doubt on the models' accuracy. To address this uncertainty, we investigated the effects of Reynolds number on the performance and near-wake characteristics of a 3-bladed cross-flow turbine, both experimentally and numerically. Mechanical power output and overall streamwise drag were measured in a towing tank at turbine diameter Reynolds numbers ReD = 0 . 5 ×105 - 2 . 0 ×106 . A detailed map of the near-wake one turbine diameter downstream was acquired via acoustic Doppler velocimetry for each Reynolds number case, from which differences in the mean velocity, turbulence intensity, and Reynolds stresses are highlighted. Finally, Reynolds-averaged Navier-Stokes (RANS) numerical simulations were performed, the results from which are compared with the experimental data. Work supported by NSF-CBET grant 1150797.

  14. Rapid Sample Processing for Detection of Food-Borne Pathogens via Cross-Flow Microfiltration

    PubMed Central

    Li, Xuan; Ximenes, Eduardo; Amalaradjou, Mary Anne Roshni; Vibbert, Hunter B.; Foster, Kirk; Jones, Jim; Liu, Xingya; Bhunia, Arun K.

    2013-01-01

    This paper reports an approach to enable rapid concentration and recovery of bacterial cells from aqueous chicken homogenates as a preanalytical step of detection. This approach includes biochemical pretreatment and prefiltration of food samples and development of an automated cell concentration instrument based on cross-flow microfiltration. A polysulfone hollow-fiber membrane module having a nominal pore size of 0.2 μm constitutes the core of the cell concentration instrument. The aqueous chicken homogenate samples were circulated within the cross-flow system achieving 500- to 1,000-fold concentration of inoculated Salmonella enterica serovar Enteritidis and naturally occurring microbiota with 70% recovery of viable cells as determined by plate counting and quantitative PCR (qPCR) within 35 to 45 min. These steps enabled 10 CFU/ml microorganisms in chicken homogenates or 102 CFU/g chicken to be quantified. Cleaning and sterilizing the instrument and membrane module by stepwise hydraulic and chemical cleaning (sodium hydroxide and ethanol) enabled reuse of the membrane 15 times before replacement. This approach begins to address the critical need for the food industry for detecting food pathogens within 6 h or less. PMID:24014538

  15. Investigation of the flow-field in the upper respiratory system when wearing N95 filtering facepiece respirator.

    PubMed

    Zhang, Xiaotie; Li, Hui; Shen, Shengnan; Cai, Mang

    2016-01-01

    This article presents a reverse modeling of the headform when wearing a filtering facepiece respirator (FFR) and a computational fluid dynamics (CFD) simulation based on the modeling. The whole model containing the upper respiratory airway, headform, and FFR was directly recorded by computed tomography (CT) scanning, and a medical contrast medium was used to make the FFR "visible." The FFR was normally worn by the subject during CT scanning so that the actual deformation of both the FFR and the face muscles during contact can be objectively conserved. The reverse modeling approach was introduced to rebuild the geometric model and convert it into a CFD solvable model. In this model, we conducted a transient numerical simulation of air flow containing carbon dioxide, thermal dynamics, and pressure and wall shear stress distribution in the respiratory system taking into consideration an individual wearing a FFR. The breathing cycle was described as a time-dependent profile of the air velocity through the respiratory airway. The result shows that wearing the N95 FFR results in CO2 accumulation, an increase in temperature and pressure elevation inside the FFR cavity. The volume fraction of CO2 reaches 1.2% after 7 breathing cycles and then is maintained at 3.04% on average. The wearers re-inhale excessive CO2 in every breathing cycle from the FFR cavity. The air temperature in the FFR cavity increases rapidly at first and then stays close to the exhaled temperature. Compared to not wearing an FFR, wearers have to increase approximately 90 Pa more pressure to keep the same breathing flow rate of 30.54 L/min after wearing an FFR. The nasal vestibule bears more wall shear stress than any other area in the airway. PMID:26653154

  16. Investigation of the flow-field in the upper respiratory system when wearing N95 filtering facepiece respirator.

    PubMed

    Zhang, Xiaotie; Li, Hui; Shen, Shengnan; Cai, Mang

    2016-01-01

    This article presents a reverse modeling of the headform when wearing a filtering facepiece respirator (FFR) and a computational fluid dynamics (CFD) simulation based on the modeling. The whole model containing the upper respiratory airway, headform, and FFR was directly recorded by computed tomography (CT) scanning, and a medical contrast medium was used to make the FFR "visible." The FFR was normally worn by the subject during CT scanning so that the actual deformation of both the FFR and the face muscles during contact can be objectively conserved. The reverse modeling approach was introduced to rebuild the geometric model and convert it into a CFD solvable model. In this model, we conducted a transient numerical simulation of air flow containing carbon dioxide, thermal dynamics, and pressure and wall shear stress distribution in the respiratory system taking into consideration an individual wearing a FFR. The breathing cycle was described as a time-dependent profile of the air velocity through the respiratory airway. The result shows that wearing the N95 FFR results in CO2 accumulation, an increase in temperature and pressure elevation inside the FFR cavity. The volume fraction of CO2 reaches 1.2% after 7 breathing cycles and then is maintained at 3.04% on average. The wearers re-inhale excessive CO2 in every breathing cycle from the FFR cavity. The air temperature in the FFR cavity increases rapidly at first and then stays close to the exhaled temperature. Compared to not wearing an FFR, wearers have to increase approximately 90 Pa more pressure to keep the same breathing flow rate of 30.54 L/min after wearing an FFR. The nasal vestibule bears more wall shear stress than any other area in the airway.

  17. Cross-Roll Flow Forming of ODS Alloy Heat Exchanger Tubes For Hoop Creep Enhancement

    SciTech Connect

    Bimal Kad

    2007-09-30

    Mechanically alloyed oxide dispersion strengthened (ODS) Fe-Cr-Al alloy thin walled tubes and sheets, produced via powder processing and consolidation methodologies are promising materials for eventual use at temperatures up to 1200 C in the power generation industry, far above the temperature capabilities of conventional alloys. Target end-uses range from gas turbine combustor liners to high aspect ratio (L/D) heat exchanger tubes. Grain boundary creep processes at service temperatures, particularly those acting in the hoop direction, are the dominant failure mechanisms for such components. The processed microstructure of ODS alloys consists of high aspect ratio grains aligned parallel to the tube axis, a result of dominant axial metal flow which aligns the dispersoid particles and other impurities in the longitudinal direction. The dispersion distribution is unaltered on a micro scale by recrystallization thermal treatments, but the high aspect ratio grain shape typically obtained limits transverse grain spacing and consequently the hoop creep response. Improving hoop creep in ODS-alloy components will require understanding and manipulating the factors that control the recrystallization behavior, and represents a critical materials design and development challenge that must be overcome in order to fully exploit the potential of ODS alloys. The objectives of this program were to (1) increase creep-strength at temperature in ODS-alloy tube and liner components by 100% via, (2) preferential cross-roll flow forming and grain/particle fibering in the critical hoop direction. The research program outlined was iterative and intended to systematically (i) examine and identify post-extrusion forming methodologies to create hoop strengthened tubes, to be (ii) evaluated at 'in-service' loads at service temperatures and environments. Our report outlines the significant hoop creep enhancements possible via secondary cross-rolling and/or flow-forming operations. Each of the

  18. Bacterial community involved in the nitrogen cycle in a down-flow sponge-based trickling filter treating UASB effluent.

    PubMed

    Mac Conell, E F A; Almeida, P G S; Martins, K E L; Araújo, J C; Chernicharo, C A L

    2015-01-01

    The bacterial community composition of a down-flow sponge-based trickling filter treating upflow anaerobic sludge blanket (UASB) effluent was investigated by pyrosequencing. Bacterial community composition considerably changed along the reactor and over the operational period. The dominant phyla detected were Proteobacteria, Verrucomicrobia, and Planctomycetes. The abundance of denitrifiers decreased from the top to the bottom and it was consistent with the organic matter concentration gradients. At lower loadings (organic and nitrogen loading rates), the abundance of anammox bacteria was higher than that of the ammonium-oxidizing bacteria in the upper portion of the reactor, suggesting that aerobic and anaerobic ammonium oxidation occurred. Nitrification occurred in all the compartments, while anammox bacteria prominently appeared even in the presence of high organic carbon to ammonia ratios (around 1.0-2.0 gCOD gN(-1)). The results suggest that denitrifiers, nitrifiers, and anammox bacteria coexisted in the reactor; thus, different metabolic pathways were involved in ammonium removal in the post-UASB reactor sponge-based.

  19. Field-scale application of Ensemble Kalman filter assimilation of transient groundwater flow data via stochastic moment equations

    NASA Astrophysics Data System (ADS)

    Panzeri, Marco; Riva, Monica; Guadagnini, Alberto; Neuman, Shlomo P.

    2014-05-01

    The ensemble Kalman filter (EnKF) enables one to assimilate newly available data in transient groundwater and other temporal earth system models through real-time Bayesian updating of system states (e.g., hydraulic heads) and parameters (e.g., hydraulic conductivities). It has become common to treat spatially varying hydraulic conductivities as autocorrelated random fields conditioned on measured conductivities and/or heads. Doing so renders the corresponding groundwater flow equations stochastic. Assimilating data in such equations via traditional EnKF entails computationally intensive Monte Carlo (MC) simulation. We have previously illustrated a methodology to circumvent the need for MC. Our methodology is grounded on (1) an approximate direct solution of nonlocal (integrodifferential) equations that govern the space-time evolution of conditional ensemble means (statistical expectations) and covariances of hydraulic heads and fluxes and (2) the embedding of these moments in EnKF. This provides sequential updates of conductivity and head estimates throughout the space-time domain of interest, does not suffer from inbreeding issues and, as an additional benefit, obviates the need for computationally intensive batch inverse solution of the moment equations as we have been doing previously. We compare the performance of our new EnKF approach based on stochastic moment equation and of the traditional Monte Carlo approach. We do so for a field scale scenario involving a sequence of pumping tests performed in a heterogeneous alluvial test site located near the city of Tuebingen, Germany.

  20. Enhanced azo dye removal in a continuously operated up-flow anaerobic filter packed with henna plant biomass.

    PubMed

    Huang, Jingang; Wu, Mengke; Chen, Jianjun; Liu, Xiuyan; Chen, Tingting; Wen, Yue; Tang, Junhong; Xie, Zhengmiao

    2015-12-15

    Effects of henna plant biomass (stem) packed in an up-flow anaerobic bio-filter (UAF) on an azo dye (AO7) removal were investigated. AO7 removal, sulfanilic acid (SA) formation, and pseudo first-order kinetic constants for these reactions (kAO7 and kSA) were higher in the henna-added UAF (R2) than in the control UAF without henna (R1). The maximum kAO7 in R1 and R2 were 0.0345 and 0.2024 cm(-1), respectively, on day 18; the corresponding molar ratios of SA formation to AO7 removal were 0.582 and 0.990. Adsorption and endogenous bio-reduction were the main AO7 removal pathways in R1, while in R2 bio-reduction was the dominant. Organics in henna could be released and fermented to volatile fatty acids, acting as effective electron donors for AO7 reduction, which was accelerated by soluble and/or fixed lawsone. Afterwards, the removal process weakened over time, indicating the demand of electron donation and lawsone-releasing during the long-term operation of UAF.

  1. Bacterial community involved in the nitrogen cycle in a down-flow sponge-based trickling filter treating UASB effluent.

    PubMed

    Mac Conell, E F A; Almeida, P G S; Martins, K E L; Araújo, J C; Chernicharo, C A L

    2015-01-01

    The bacterial community composition of a down-flow sponge-based trickling filter treating upflow anaerobic sludge blanket (UASB) effluent was investigated by pyrosequencing. Bacterial community composition considerably changed along the reactor and over the operational period. The dominant phyla detected were Proteobacteria, Verrucomicrobia, and Planctomycetes. The abundance of denitrifiers decreased from the top to the bottom and it was consistent with the organic matter concentration gradients. At lower loadings (organic and nitrogen loading rates), the abundance of anammox bacteria was higher than that of the ammonium-oxidizing bacteria in the upper portion of the reactor, suggesting that aerobic and anaerobic ammonium oxidation occurred. Nitrification occurred in all the compartments, while anammox bacteria prominently appeared even in the presence of high organic carbon to ammonia ratios (around 1.0-2.0 gCOD gN(-1)). The results suggest that denitrifiers, nitrifiers, and anammox bacteria coexisted in the reactor; thus, different metabolic pathways were involved in ammonium removal in the post-UASB reactor sponge-based. PMID:26114279

  2. Performance Evaluation, Emulation, and Control of Cross-Flow Hydrokinetic Turbines

    NASA Astrophysics Data System (ADS)

    Cavagnaro, Robert J.

    Cross-flow hydrokinetic turbines are a promising option for effectively harvesting energy from fast-flowing streams or currents. This work describes the dynamics of such turbines, analyzes techniques used to scale turbine properties for prototyping, determines and demonstrates the limits of stability for cross-flow rotors, and discusses means and objectives of turbine control. Novel control strategies are under development to utilize low-speed operation (slower than at maximum power point) as a means of shedding power under rated conditions. However, operation in this regime may be unstable. An experiment designed to characterize the stability of a laboratory-scale cross-flow turbine operating near a critically low speed yields evidence that system stall (complete loss of ability to rotate) occurs due, in part, to interactions with turbulent decreases in flow speed. The turbine is capable of maintaining 'stable' operation at critical speed for short duration (typically less than 10 s), as described by exponential decay. The presence of accelerated 'bypass' flow around the rotor and decelerated 'induction' region directly upstream of the rotor, both predicted by linear momentum theory, are observed and quantified with particle image velocimetry (PIV) measurements conducted upstream of the turbine. Additionally, general agreement is seen between PIV inflow measurements and those obtained by an advection-corrected acoustic Doppler velocimeter (ADV) further upstream. Performance of a turbine at small (prototype) geometric scale may be prone to undesirable effects due to operation at low Reynolds number and in the presence of high channel blockage. Therefore, testing at larger scale, in open water is desirable. A cross-flow hydrokinetic turbine with a projected area (product of blade span and rotor diameter) of 0.7 m2 is evaluated in open-water tow trials at three inflow speeds ranging from 1.0 m/s to 2.1 m/s. Measurements of the inflow velocity, the rotor mechanical

  3. On the use of the periodicity condition in cross-flow tube

    NASA Astrophysics Data System (ADS)

    Beladjine, Boumedienne; Aounallah, Mohammed; Belkadi, Mustapha; Aadjlout, Lahouari; Imine, Omar

    2015-05-01

    This paper presents the results of measurements and numerical predictions of turbulent cross-flow through an in-line 7×7 bundle configuration with a constant transverse and longitudinal pitch-to-diameter ratio of 1.44. The experiments are conducted to measure the pressure around tubes, using DPS differential pressure scanner with air flow, in square channel at a Reynolds number of 35000 based on the gap velocity and the tube diameter. The commercial ANSYS FLUENT is used to solve the unsteady Reynolds-Averaged Navier-Stokes (RANS) equations. The primary aim of the present study is to search for a turbulent model that could serve as an engineering design tool at a relatively low computational cost. The performances of the Spalart-Allmaras, the RNG k-ɛ, the Shear Stress Transport k-ω and the second moment closure RSM models are evaluated by comparing their simulation results against experimental data. The second objective is to verify the validity of the periodicity assumption taken account in the most previous numerical works by considering the filled bundle geometry. The CFD results show that the Spalart-Allmaras model on the fine mesh are comparable to the experiments while the periodicity statement did not produce consistently the flow behavior in the 7×7 tube bundle configuration.

  4. An Isolated Circular Synthetic Jet in Cross-Flow at Low Momentum-Flux Ratio

    NASA Technical Reports Server (NTRS)

    Milanovic, Ivana M.; Zaman, Khairul B. M. Q.; Rumsey, Christopher L.

    2005-01-01

    A joint experimental and computational investigation was carried out for a round synthetic jet issuing normal to a turbulent boundary layer at a momentum-flux ratio of one. Distributions of velocity and turbulence intensity were measured by hot-wire anemometry. Numerical results were obtained using unsteady Reynolds-averaged Navier-Stokes (URANS) computations. Time and phase-averaged flow properties were compared on the cross sectional plane at x/D = 0.53, 5 and 10 as well as on the axial plane of symmetry. Overall, the numerical results agreed well with the experimental data. CFD predicted a somewhat larger velocity deficit in regions of low-momentum fluid pulled up from the boundary layer. Phase- averaged velocity contours at the plane of symmetry indicated good match between experiments and CFD regarding the size and the position of the periodic flow structure. However, some differences occurred in details such as the shape and inclination of the low-speed flow structure.

  5. Active Control of Jets in Cross-Flow for Film Cooling Applications

    NASA Technical Reports Server (NTRS)

    Nikitopoulos, Dimitris E.

    2003-01-01

    Jets in cross-flow have applications in film cooling of gas turbine vanes, blades and combustor liners. Their cooling effectiveness depends on the extent to which the cool jet-fluid adheres to the cooled component surface. Lift-off of the cooling jet flow or other mechanisms promoting mixing, cause loss of cooling effectiveness as they allow the hot "free-stream" fluid to come in contact with the component surface. The premise of this project is that cooling effectiveness can be improved by actively controlling (e.9. forcing, pulsing) the jet flow. Active control can be applied to prevent/delay lift-off and suppress mixing. Furthermore, an actively controlled film-cooling system coupled with appropriate sensory input (e.g. temperature or heat flux) can adapt to spatial and temporal variations of the hot-gas path. Thus, it is conceivable that the efficiency of film-cooling systems can be improved, resulting in coolant fluid economy. It is envisioned that Micro Electro-Mechanical Systems (MEMS) will play a role in the realization of such systems. As a first step, a feasibility study will be conducted to evaluate the concept, identify actuation and sensory elements and develop a control strategy. Part of this study will be the design of a proof-of-concept experiment and collection of necessary data.

  6. Interactions of a finite span synthetic jet with a cross flow

    NASA Astrophysics Data System (ADS)

    Leong, Chia Min; van Buren, Tyler; Whalen, Edward; Amitay, Michael; Rensselaer Polytechnic Institute Team; Boeing Collaboration

    2013-11-01

    A synthetic jet is a zero-net-mass-flux flow control actuator that produces alternating ejection and suction of fluid momentum across an orifice. It has been used in numerous applications as an active flow control device to improve aerodynamic performance. Though their aerodynamic performance effects are well known, this present study seeks to understand the fluid dynamic effects of synthetic jets. Specifically, the work investigates the interactions of a finite span synthetic jet with a zero-pressure-gradient laminar boundary layer. This study was performed in a small-scale subsonic wind tunnel with an adjustable test section upper wall that was used to generate a zero-pressure-gradient boundary layer. Several finite span rectangular orifices were chosen for this study. Time and phase-averaged Stereoscopic Particle Image Velocimetry (SPIV) measurements were acquired at multiple planes upstream and downstream of the synthetic jet orifice to explore the interaction of the synthetic jet with the cross flow. The effects of the orifice aspect ratio (12, 18, and 24) and blowing ratio (0.5, 1, and 1.5) were investigated. The unsteady vortical structures observed in the near field and the steady structures in the far field are discussed.

  7. Spatial Mapping of Flow-Induced Molecular Alignment in a Noncrystalline Biopolymer Fluid Using Double Quantum Filtered (DQF) (23)Na MRI.

    PubMed

    Pavlovskaya, Galina E; Meersmann, Thomas

    2014-08-01

    Flow-induced molecular alignment was observed experimentally in a non-liquid-crystalline bioplymeric fluid during developed tubular flow. The fluid was comprised of rigid rods of the polysaccharide xanthan and exhibited shear-thinning behavior. Without a requirement for optical transparency or the need for an added tracer, (23)Na magic angle (MA) double quantum filtered (DQF) magnetic resonance imaging (MRI) enabled the mapping of the anisotropic molecular arrangement under flow conditions. A regional net molecular alignment was found in areas of high shear values in the vicinity of the tube wall. Furthermore, the xanthan molecules resumed random orientations after the cessation of flow. The observed flow-induced molecular alignment was correlated with the rheological properties of the fluid. The work demonstrates the ability of (23)Na MA DQF magnetic resonance to provide a valuable molecular-mechanical link. PMID:26277955

  8. Particle loading time and humidity effects on the efficiency of an N95 filtering facepiece respirator model under constant and inhalation cyclic flows.

    PubMed

    Mahdavi, Alireza; Haghighat, Fariborz; Bahloul, Ali; Brochot, Clothilde; Ostiguy, Claude

    2015-06-01

    It is necessary to investigate the efficiencies of filtering facepiece respirators (FFRs) exposed to ultrafine particles (UFPs) for long periods of time, since the particle loading time may potentially affect the efficiency of FFRs. This article aims to investigate the filtration efficiency for a model of electrostatic N95 FFRs with constant and 'inhalation-only' cyclic flows, in terms of particle loading time effect, using different humidity conditions. Filters were exposed to generated polydisperse NaCl particles. Experiments were performed mimicking an 'inhalation-only' scenario with a cyclic flow of 85 l min(-1) as the minute volume [or 170 l min(-1) as mean inhalation flow (MIF)] and for two constant flows of 85 and 170 l min(-1), under three relative humidity (RH) levels of 10, 50, and 80%. Each test was performed for loading time periods of 6h and the particle penetration (10-205.4nm in electrical mobility diameter) was measured once every 2h. For a 10% RH, the penetration of smaller size particles (<80nm), including the most penetrating particle size (MPPS), decreased over time for both constant and cyclic flows. For 50 and 80% RH levels, the changes in penetration were typically observed in an opposite direction with less magnitude. The penetrations at MPPS increased with respect to loading time under constant flow conditions (85 and 170 l min(-1)): it did not substantially increase under cyclic flows. The comparison of the cyclic flow (85 l min(-1) as minute volume) and constant flow equal to the cyclic flow minute volume indicated that, for all conditions the penetration was significantly less for the constant flow than that of cyclic flow. The comparison between the cyclic (170 l min(-1) as MIF) and constant flow equal to cyclic flow MIF indicated that, for the initial stage of loading, the penetrations were almost equal, but they were different for the final stages of the loading time. For a 10% RH, the penetration of a wide range of sizes was observed

  9. Particle loading time and humidity effects on the efficiency of an N95 filtering facepiece respirator model under constant and inhalation cyclic flows.

    PubMed

    Mahdavi, Alireza; Haghighat, Fariborz; Bahloul, Ali; Brochot, Clothilde; Ostiguy, Claude

    2015-06-01

    It is necessary to investigate the efficiencies of filtering facepiece respirators (FFRs) exposed to ultrafine particles (UFPs) for long periods of time, since the particle loading time may potentially affect the efficiency of FFRs. This article aims to investigate the filtration efficiency for a model of electrostatic N95 FFRs with constant and 'inhalation-only' cyclic flows, in terms of particle loading time effect, using different humidity conditions. Filters were exposed to generated polydisperse NaCl particles. Experiments were performed mimicking an 'inhalation-only' scenario with a cyclic flow of 85 l min(-1) as the minute volume [or 170 l min(-1) as mean inhalation flow (MIF)] and for two constant flows of 85 and 170 l min(-1), under three relative humidity (RH) levels of 10, 50, and 80%. Each test was performed for loading time periods of 6h and the particle penetration (10-205.4nm in electrical mobility diameter) was measured once every 2h. For a 10% RH, the penetration of smaller size particles (<80nm), including the most penetrating particle size (MPPS), decreased over time for both constant and cyclic flows. For 50 and 80% RH levels, the changes in penetration were typically observed in an opposite direction with less magnitude. The penetrations at MPPS increased with respect to loading time under constant flow conditions (85 and 170 l min(-1)): it did not substantially increase under cyclic flows. The comparison of the cyclic flow (85 l min(-1) as minute volume) and constant flow equal to the cyclic flow minute volume indicated that, for all conditions the penetration was significantly less for the constant flow than that of cyclic flow. The comparison between the cyclic (170 l min(-1) as MIF) and constant flow equal to cyclic flow MIF indicated that, for the initial stage of loading, the penetrations were almost equal, but they were different for the final stages of the loading time. For a 10% RH, the penetration of a wide range of sizes was observed

  10. ARRANGEMENT FOR REPLACING FILTERS

    DOEpatents

    Blomgren, R.A.; Bohlin, N.J.C.

    1957-08-27

    An improved filtered air exhaust system which may be continually operated during the replacement of the filters without the escape of unfiltered air is described. This is accomplished by hermetically sealing the box like filter containers in a rectangular tunnel with neoprene covered sponge rubber sealing rings coated with a silicone impregnated pneumatic grease. The tunnel through which the filters are pushed is normal to the exhaust air duct. A number of unused filters are in line behind the filters in use, and are moved by a hydraulic ram so that a fresh filter is positioned in the air duct. The used filter is pushed into a waiting receptacle and is suitably disposed. This device permits a rapid and safe replacement of a radiation contaminated filter without interruption to the normal flow of exhaust air.

  11. Flow structures and red blood cell dynamics in arteriole of dilated or constricted cross section.

    PubMed

    Gambaruto, Alberto M

    2016-07-26

    Vessel with 'circular' or 'star-shaped' cross sections are studied, representing respectively dilated or constricted cases where endothelial cells smoothly line or bulge into the lumen. Computational haemodynamics simulations are carried out on idealised periodic arteriole-sized vessels, with red blood cell 'tube' hematocrit value=24%. A further simulation of a single red blood cell serves for comparison purposes. The bulk motion of the red blood cells reproduces well-known effects, including the presence of a cell-free layer and the apparent shear-thinning non-Newtonian rheology. The velocity flow field is analysed in a Lagrangian reference frame, relative to any given red blood cell, hence removing the bulk coaxial motion and highlighting instead the complex secondary flow patterns. An aggregate formation becomes apparent, continuously rearranging and dynamic, brought about by the inter-cellular fluid mechanics interactions and the deformability properties of the cells. The secondary flow field induces a vacillating radial migration of the red blood cells. At different radial locations, the red blood cells express different residence times, orientation and shape. The shear stresses exerted by the flow on the vessel wall are influenced by the motion of red blood cells, despite the presence of the cell-free layer. Spatial (and temporal) variations of wall shear stress patters are observed, especially for the 'circular' vessel. The 'star-shaped' vessel bears considerable stress at the protruding endothelial cell crests, where the stress vectors are coaxially aligned. The bulging endothelial cells hence regularise the transmission of stresses on the vessel wall. PMID:26822224

  12. Flow structures and red blood cell dynamics in arteriole of dilated or constricted cross section.

    PubMed

    Gambaruto, Alberto M

    2016-07-26

    Vessel with 'circular' or 'star-shaped' cross sections are studied, representing respectively dilated or constricted cases where endothelial cells smoothly line or bulge into the lumen. Computational haemodynamics simulations are carried out on idealised periodic arteriole-sized vessels, with red blood cell 'tube' hematocrit value=24%. A further simulation of a single red blood cell serves for comparison purposes. The bulk motion of the red blood cells reproduces well-known effects, including the presence of a cell-free layer and the apparent shear-thinning non-Newtonian rheology. The velocity flow field is analysed in a Lagrangian reference frame, relative to any given red blood cell, hence removing the bulk coaxial motion and highlighting instead the complex secondary flow patterns. An aggregate formation becomes apparent, continuously rearranging and dynamic, brought about by the inter-cellular fluid mechanics interactions and the deformability properties of the cells. The secondary flow field induces a vacillating radial migration of the red blood cells. At different radial locations, the red blood cells express different residence times, orientation and shape. The shear stresses exerted by the flow on the vessel wall are influenced by the motion of red blood cells, despite the presence of the cell-free layer. Spatial (and temporal) variations of wall shear stress patters are observed, especially for the 'circular' vessel. The 'star-shaped' vessel bears considerable stress at the protruding endothelial cell crests, where the stress vectors are coaxially aligned. The bulging endothelial cells hence regularise the transmission of stresses on the vessel wall.

  13. Interactions between seagrass complexity, hydrodynamic flow and biomixing alter food availability for associated filter-feeding organisms.

    PubMed

    González-Ortiz, Vanessa; Egea, Luis G; Jiménez-Ramos, Rocio; Moreno-Marín, Francisco; Pérez-Lloréns, José L; Bouma, Tjeed J; Brun, Fernando G

    2014-01-01

    Seagrass shoots interact with hydrodynamic forces and thereby a positively or negatively influence the survival of associated species. The modification of these forces indirectly alters the physical transport and flux of edible particles within seagrass meadows, which will influence the growth and survivorship of associated filter-feeding organisms. The present work contributes to gaining insight into the mechanisms controlling the availability of resources for filter feeders inhabiting seagrass canopies, both from physical (influenced by seagrass density and patchiness) and biological (regulated by filter feeder density) perspectives. A factorial experiment was conducted in a large racetrack flume, which combined changes in hydrodynamic conditions, chlorophyll a concentration in the water and food intake rate (FIR) in a model active filter-feeding organism (the cockle). Results showed that seagrass density and patchiness modified both hydrodynamic forces and availability of resources for filter feeders. Chlorophyll a water content decreased to 50% of the initial value when densities of both seagrass shoots and cockles were high. Also, filter feeder density controlled resource availability within seagrass patches, depending on its spatial position within the racetrack flume. Under high density of filter-feeding organisms, chlorophyll a levels were lower between patches. This suggests that the pumping activity of cockles (i.e. biomixing) is an emergent key factor affecting both resource availability and FIR for filter feeders in dense canopies. Applying our results to natural conditions, we suggest the existence of a direct correlation between habitat complexity (i.e. shoot density and degree of patchiness) and filter feeders density. Fragmented and low-density patches seem to offer both greater protection from hydrodynamic forces and higher resource availability. In denser patches, however, resources are allocated mostly within the canopy, which would benefit

  14. Interactions between Seagrass Complexity, Hydrodynamic Flow and Biomixing Alter Food Availability for Associated Filter-Feeding Organisms

    PubMed Central

    González-Ortiz, Vanessa; Egea, Luis G.; Jiménez-Ramos, Rocio; Moreno-Marín, Francisco; Pérez-Lloréns, José L.; Bouma, Tjeed J.; Brun, Fernando G.

    2014-01-01

    Seagrass shoots interact with hydrodynamic forces and thereby a positively or negatively influence the survival of associated species. The modification of these forces indirectly alters the physical transport and flux of edible particles within seagrass meadows, which will influence the growth and survivorship of associated filter-feeding organisms. The present work contributes to gaining insight into the mechanisms controlling the availability of resources for filter feeders inhabiting seagrass canopies, both from physical (influenced by seagrass density and patchiness) and biological (regulated by filter feeder density) perspectives. A factorial experiment was conducted in a large racetrack flume, which combined changes in hydrodynamic conditions, chlorophyll a concentration in the water and food intake rate (FIR) in a model active filter-feeding organism (the cockle). Results showed that seagrass density and patchiness modified both hydrodynamic forces and availability of resources for filter feeders. Chlorophyll a water content decreased to 50% of the initial value when densities of both seagrass shoots and cockles were high. Also, filter feeder density controlled resource availability within seagrass patches, depending on its spatial position within the racetrack flume. Under high density of filter-feeding organisms, chlorophyll a levels were lower between patches. This suggests that the pumping activity of cockles (i.e. biomixing) is an emergent key factor affecting both resource availability and FIR for filter feeders in dense canopies. Applying our results to natural conditions, we suggest the existence of a direct correlation between habitat complexity (i.e. shoot density and degree of patchiness) and filter feeders density. Fragmented and low-density patches seem to offer both greater protection from hydrodynamic forces and higher resource availability. In denser patches, however, resources are allocated mostly within the canopy, which would benefit

  15. Interactions between seagrass complexity, hydrodynamic flow and biomixing alter food availability for associated filter-feeding organisms.

    PubMed

    González-Ortiz, Vanessa; Egea, Luis G; Jiménez-Ramos, Rocio; Moreno-Marín, Francisco; Pérez-Lloréns, José L; Bouma, Tjeed J; Brun, Fernando G

    2014-01-01

    Seagrass shoots interact with hydrodynamic forces and thereby a positively or negatively influence the survival of associated species. The modification of these forces indirectly alters the physical transport and flux of edible particles within seagrass meadows, which will influence the growth and survivorship of associated filter-feeding organisms. The present work contributes to gaining insight into the mechanisms controlling the availability of resources for filter feeders inhabiting seagrass canopies, both from physical (influenced by seagrass density and patchiness) and biological (regulated by filter feeder density) perspectives. A factorial experiment was conducted in a large racetrack flume, which combined changes in hydrodynamic conditions, chlorophyll a concentration in the water and food intake rate (FIR) in a model active filter-feeding organism (the cockle). Results showed that seagrass density and patchiness modified both hydrodynamic forces and availability of resources for filter feeders. Chlorophyll a water content decreased to 50% of the initial value when densities of both seagrass shoots and cockles were high. Also, filter feeder density controlled resource availability within seagrass patches, depending on its spatial position within the racetrack flume. Under high density of filter-feeding organisms, chlorophyll a levels were lower between patches. This suggests that the pumping activity of cockles (i.e. biomixing) is an emergent key factor affecting both resource availability and FIR for filter feeders in dense canopies. Applying our results to natural conditions, we suggest the existence of a direct correlation between habitat complexity (i.e. shoot density and degree of patchiness) and filter feeders density. Fragmented and low-density patches seem to offer both greater protection from hydrodynamic forces and higher resource availability. In denser patches, however, resources are allocated mostly within the canopy, which would benefit

  16. Flow structure caused by a local cross-sectional area increase and curvature in sharp river bends

    NASA Astrophysics Data System (ADS)

    Vermeulen, B.

    2015-12-01

    Horizontal flow recirculation is often observed in sharp river bends, causing a complex three-dimensional flow structure with large implications for the morphological and planimetric development of meanders. Several field observations in small scale systems show that sharp bends are often found in association with a strong increase in cross-sectional area, the deposition of outer bank benches and reattachment bars near the inner bank. Recent studies show that these bends can also occur in large scale systems. In this study, we present field measurements of a sharp bend in the Mahakam River, East Kalimantan, Indonesia. The cross-sectional area increases by a factor of three compared with the reach averaged cross-sectional area. Along a river reach of about 150 km, cross-sectional area correlates strongly with curvature. The field measurements are analyzed together with the results from numerical simulation with a 3D finite element model, which yields a comprehensive view of the intricate flow structure. In turn, the model is used to validate a new equation that captures the water surface topography dependence on cross-sectional area variation and curvature. The results show the importance of the increase in cross-sectional area in the development of horizontal recirculation. Vertical acceleration of the flow into the scour causes the pressure to deviate from a hydrostatic pressure distribution. Strong downflow (up to 12 cm/s) advects longitudinal momentum towards the bed, causing the flow to concentrate in the lower part of the cross-section. This increases the velocity magnitude throughout the cross-section, which is expected to maintain the large scour depth found in several bends along the Mahakam River.

  17. Vortical flow control on a conical fore body cross section using an array of pulsed dc actuators

    SciTech Connect

    Singh, Kunwar Pal; Roy, Subrata

    2007-05-01

    Flow control on a conical fore body cross section of an aircraft is studied using plasma discharge by considering the neutral gas flow at 17.5 deg angle of attack. The equations governing the motion of electrons, ions as well as Poisson's equation are solved together with Navier-Stokes and energy equation for neutrals to study flow control. A single barrier discharge actuator is not sufficient to control the flow on the entire length of the fore body. An arrangement of multiple electrodes powered with pulsed dc voltage has been suggested for controlling such flows. The effects of joule heating of plasma, dielectric heating, and electrodynamic force have been investigated, separately and then combined on flow control. It is found that joule heating results in high temperature of the dielectric surface, however; electrodynamic force contributes prominently to flow control. A three-dimensional analysis is necessary to validate results with experiments.

  18. Separated flow over bodies of revolution using an unsteady discrete-vorticity cross wake. Part 1: Theory and application

    NASA Technical Reports Server (NTRS)

    Marshall, F. J.; Deffenbaugh, F. D.

    1974-01-01

    A method is developed to determine the flow field of a body of revolution in separated flow. The technique employed is the use of the computer to integrate various solutions and solution properties of the sub-flow fields which made up the entire flow field without resorting to a finite difference solution to the complete Navier-Stokes equations. The technique entails the use of the unsteady cross flow analogy and a new solution to the required two-dimensional unsteady separated flow problem based upon an unsteady, discrete-vorticity wake. Data for the forces and moments on aerodynamic bodies at low speeds and high angle of attack (outside the range of linear inviscid theories) such that the flow is substantially separated are produced which compare well with experimental data. In addition, three dimensional steady separation regions and wake vortex patterns are determined.

  19. Cross-Roll Flow Forming of ODS Alloy Heat Exchanger Tubes For Hoop Creep Enhancement

    SciTech Connect

    Bimal K. Kad

    2005-11-23

    Mechanically alloyed oxide dispersion strengthened (ODS) Fe-Cr-Al alloy thin walled tubes and sheets, produced via powder processing and consolidation methodologies, are promising materials for eventual use at temperatures up to 1200 C in the power generation industry, far above the temperature capabilities of conventional alloys. Target end-uses range from gas turbine combustor liners to high aspect ratio (L/D) heat exchanger tubes. Grain boundary creep processes at service temperatures, particularly those acting in the hoop direction, are the dominant failure mechanisms for such components. The processed microstructure of ODS alloys consists of high aspect ratio grains aligned parallel to the tube axis, a result of dominant axial metal flow which aligns the dispersoid particles and other impurities in the longitudinal direction. The dispersion distribution is unaltered on a micro scale by recrystallization thermal treatments, but the high aspect ratio grain shape typically obtained limits transverse grain spacing and consequently the hoop creep response. Improving hoop creep in ODS-alloy components will require understanding and manipulating the factors that control the recrystallization behavior, and represents a critical materials design and development challenge that must be overcome in order to fully exploit the potential of ODS alloys. The objectives of this program are to (1) increase creep-strength at temperature in ODS-alloy tube and liner components by 100% via, (2) preferential cross-roll flow forming and grain/particle fibering in the critical hoop direction. Recent studies in crossrolled ODS-alloy sheets (produced from flattened tubes) indicate that transverse creep is significantly enhanced via controlled transverse grain fibering, and similar improvements are expected for cross-rolled tubes. The research program outlined here is iterative in nature and is intended to systematically (1) examine and identify post-extrusion forming methodologies to

  20. Cross-flow membrane emulsification technique for fabrication of drug-loaded particles

    NASA Astrophysics Data System (ADS)

    Ho, Thanh Ha; Phuong Tuyen Dao, Thi; Nguyen, Tuan Anh; Dam Le, Duy; Chien Dang, Mau

    2013-12-01

    Cross-flow membrane emulsification is a new technique which was used in this study to achieve uniform and controllable emulsion systems. In this method, the droplet is individually formed at the pore on the surface of membrane in the more mild, controllable and efficient way as compared to traditional emulsification techniques. In this study, we used silicon nitride membranes of very precise parameters of pore size, shape and inter-pore distance in order to create curcumin loaded poly(d, l-lactic-co-glycolic acid) (PLGA) particles. It was demonstrated that more uniform and pore-size dependent particles was created by using different membrane pore sizes (ø200 nm, ø450 nm and ø2 μm). Other factors that could impact particle size and morphology such as membrane polarity, concentration and volume of two phases were investigated. Further tests on comparison to mechanical stirring method were also realized.

  1. Surface-specific flow factors for prediction of friction of cross-hatched surfaces

    NASA Astrophysics Data System (ADS)

    Leighton, M.; Rahmani, R.; Rahnejat, H.

    2016-06-01

    The paper presents a combined numerical and experimental study of generated sliding friction at low sliding speeds and high load intensity, typical of the top compression ring-cylinder liner conjunction at top dead centre in the compression stroke of high performance race engines. Frictional losses in the transition from compression to power stroke represent a significant portion of cyclic cylinder losses. The cylinder liner is cross-hatch honed with non-Gaussian topography, including larger groove features and a fairly smooth plateau roughness. Surface-specific flow factors are derived to closely represent the actual real rough conjunction. The predictions closely agree with the representative reported precision tribometric study of measured friction.

  2. Cyanide removal from industrial wastewater by cross-flow nanofiltration: transport modeling and economic evaluation.

    PubMed

    Pal, Parimal; Bhakta, Pamela; Kumar, Ramesh

    2014-08-01

    A modeling and simulation study, along with an economic analysis, was carried out for the separation of cyanide from industrial wastewater using a flat sheet cross-flow nanofiltration membrane module. With the addition of a pre-microfiltration step, nanofiltration was carried out using real coke wastewater under different operating conditions. Under the optimum operating pressure of 13 bars and a pH of 10.0, a rate of more than 95% separation of cyanide was achieved. That model predictions agreed very well with the experimental findings, as is evident in the Willmott d-index value (> 0.95) and relative error (< 0.1). Studies were carried out with industrial wastewater instead of a synthetic solution, and an economic analysis was also done, considering the capacity of a running coking plant. The findings are likely to be very useful in the scale-up and design of industrial plants for the treatment of cyanide-bearing wastewater.

  3. Modeling of energy transfer between two crossing smoothed laser beams in a plasma with flow profile

    NASA Astrophysics Data System (ADS)

    Colaitis, A.; Hüller, S.; Tikhonchuk, V. T.; Pesme, D.; Duchateau, G.; Porzio, A.

    2016-05-01

    We study the crossed beam energy transfer (CBET) between laser fields generated by optical smoothing methods. The energy transfer, as well as the angular distribution of the outgoing light fields are investigated for two incident smoothed laser beams in a plasma with a flow gradient, allowing for resonant transfer close to the sonic point. Simulations with the code HARMONY based on time-dependent paraxial light propagation are compared to simulations using a new approach based on paraxial complex geometrical optics (PCGO). Both approaches show good agreement for the average energy transfer past a short transient period, which is a promising result for the use of the PCGO method as a module within a hydrodynamics code to efficiently compute CBET in mm-scale plasma configurations. Statistical aspects related to role of laser speckles in CBET are considered via an ensemble of different phase plate realizations.

  4. An investigation into blockage corrections for cross-flow hydrokinetic turbine performance

    NASA Astrophysics Data System (ADS)

    Cavagnaro, Robert; Polagye, Brian

    2013-11-01

    The performance of hydrokinetic turbines is augmented in confined channels, such that the coefficient of performance is elevated versus free-stream conditions. This often introduces uncertainty when characterizing prototype-scale turbines in flume or tow tank facilities. Performance of a one-quarter scale helical, cross-flow turbine is characterized over a range of operating conditions (inflow velocity and tip-speed ratio) at blockage ratios (ratio of rotor swept area to channel area) of ~10 and ~25%. Particle image velocimitry is used to characterize rotor induction, as well as the turbulent wake produced by the turbine. Performance at the different blockage ratios is compared to corrections derived from actuator disk theory and to full-scale field performance in the absence of blockage.

  5. Flow past square and circular cross-section cylinders with a wavy stagnation face

    NASA Astrophysics Data System (ADS)

    Darekar, Rupad; Sherwin, Spencer

    2000-11-01

    Numerical investigations have been performed for the flow past square and circular cross-section cylinders with a spanwise geometric deformation leading to a stagnation face with a sinusoidal waviness. The computations were performed using a spectral/hp element solver over a range of Reynolds numbers from 10 to 500. Starting from fully developed shedding past a straight cylinder at a Reynolds number of 100, a sufficiently high waviness is impulsively introduced resulting in the stabilisation of the near-wake to a time-independent state. It is shown that the spanwise waviness sets up a cross-flow within the growing boundary layer on the leading edge surface thereby generating streamwise and vertical components of vorticity. These additional components of vorticity appear in regions close to the inflection points of the wavy stagnation face where the spanwise vorticity is weakened. This redistribution of vorticity leads to the breakdown of the unsteady and staggered Kármán vortex wake into a steady and symmetric near-wake structure. The steady nature of the near-wake is associated with a reduction in total drag of about 16% at a Reynolds number of 100 as compared with the straight, non-wavy cylinder. Further increases in the amplitude of the waviness lead to the emergence of hairpin vortices from the near-wake region. This wake topology has similarities to the wake of a sphere at low Reynolds numbers. The physical structure of the wake due to the variation of the amplitude of the waviness is identified with five distinct regimes. Furthermore, the introduction of a waviness at a wavelength close to the mode A wavelength and the primary wavelength of the straight square section cylinder leads to the suppression of the von-Kármán street at a minimal waviness amplitude. Results for the wavy circular cylinders will also be presented.

  6. Onsager's cross coupling effects in gas flows confined to micro-channels

    NASA Astrophysics Data System (ADS)

    Wang, Ruijie; Xu, Xinpeng; Xu, Kun; Qian, Tiezheng

    2016-08-01

    In rarefied gases, mass and heat transport processes interfere with each other, leading to the mechano-caloric effect and thermo-osmotic effect, which are of interest to both theoretical study and practical applications. We employ the unified gas-kinetic scheme to investigate these cross coupling effects in gas flows in micro-channels. Our numerical simulations cover channels of planar surfaces and also channels of ratchet surfaces, with Onsager's reciprocal relation verified for both cases. For channels of planar surfaces, simulations are performed in a wide range of Knudsen number, and our numerical results show good agreement with the literature results. For channels of ratchet surfaces, simulations are performed for both the slip and transition regimes, and our numerical results not only confirm the theoretical prediction [Phys. Rev. Lett. 107, 164502 (2011), 10.1103/PhysRevLett.107.164502] for the Knudsen number in the slip regime but also show that the off-diagonal kinetic coefficients for cross coupling effects are maximized at a Knudsen number in the transition regime. Finally, a preliminary optimization study is carried out for the geometry of Knudsen pump based on channels of ratchet surfaces.

  7. Heat transfer in oscillating flows with sudden change in cross section

    NASA Technical Reports Server (NTRS)

    Ibrahim, Mounir; Hashim, Waqar; Tew, Roy C.; Dudenhoefer, James E.

    1992-01-01

    Oscillating fluid flow (zero mean) with heat transfer, between two parallel plates with a sudden change in cross section, was examined computationally. Over 30 different cases were examined; these cases cover wide ranges of Re sub max (187.5 to 30,000), Va (1 to 350), expansion ratio (1:2, 1:4, 1:8, and 1:12) and A sub r (0.68 to 4). Three different geometric cases were considered (asymmetric expansion and/or contraction, symmetric expansion/contraction, and symmetric blunt body). The heat transfer cases were based on constant wall temperature at higher (heating) or lower (cooling) value than the inflow fluid temperature. As a result of the oscillating flow, the fluid undergoes sudden expansion in one half of the cycle and sudden contraction in the other half. Instantaneous friction factors and heat transfer coefficients, for some ranges of Re sub max and Va, deviated substantially from those predicted with steady state correlations.

  8. Wind tunnel experiments of cooling-tower plumes in the presence of cross flow

    NASA Astrophysics Data System (ADS)

    Andreopoulos, J.

    Measurements of velocity and temperature field and flow visualization results are reported for an ideal case of a cooling-tower plume in the presence of cross flow for various velocity ratios, densimetric Froude numbers, and Reynolds numbers. Coherent structures in the form of jet-like, wake-like or mushroom type of vortices have been observed. The type of the structures depends primarily on the velocity ratio. As the Reynolds number increases turbulent structures appear which carry vorticity of the same sign as the partner vortices in the low Reynolds number case. The measurements showed that there is a strong interaction between the bending over plume or jet and the wake of the cooling tower which is basically responsible for the downwash effect, which generally is quite strong at low velocity ratios and high Reynolds numbers. High turbulence intensities are produced on the wake of the tower for about 6 to 8 diameters. The plume is diluted faster as the velocity ratio and buoyancy increase.

  9. Effect of gas-liquid flow pattern and microbial diversity analysis of a pilot-scale biotrickling filter for anoxic biogas desulfurization.

    PubMed

    Almenglo, Fernando; Bezerra, Tercia; Lafuente, Javier; Gabriel, David; Ramírez, Martín; Cantero, Domingo

    2016-08-01

    Hydrogen sulfide removal from biogas was studied under anoxic conditions in a pilot-scale biotrickling filter operated under counter- and co-current gas-liquid flow patterns. The best performance was found under counter-current conditions (maximum elimination capacity of 140 gS m(-3) h(-1)). Nevertheless, switching conditions between co- and counter-current flow lead to a favorable redistribution of biomass and elemental sulfur along the bed height. Moreover, elemental sulfur was oxidized to sulfate when the feeding biogas was disconnected and the supply of nitrate (electron acceptor) was maintained. Removal of elemental sulfur was important to prevent clogging in the packed bed and, thereby, to increase the lifespan of the packed bed between maintenance episodes. The larger elemental sulfur removal rate during shutdowns was 59.1 gS m(-3) h(-1). Tag-encoded FLX amplicon pyrosequencing was used to study the diversity of bacteria under co-current flow pattern with liquid recirculation and counter-current mode with a single-pass flow of the liquid phase. The main desulfurizing bacteria were Sedimenticola while significant role of heterotrophic, opportunistic species was envisaged. Remarkable differences between communities were found when a single-pass flow of industrial water was fed to the biotrickling filter.

  10. Effect of gas-liquid flow pattern and microbial diversity analysis of a pilot-scale biotrickling filter for anoxic biogas desulfurization.

    PubMed

    Almenglo, Fernando; Bezerra, Tercia; Lafuente, Javier; Gabriel, David; Ramírez, Martín; Cantero, Domingo

    2016-08-01

    Hydrogen sulfide removal from biogas was studied under anoxic conditions in a pilot-scale biotrickling filter operated under counter- and co-current gas-liquid flow patterns. The best performance was found under counter-current conditions (maximum elimination capacity of 140 gS m(-3) h(-1)). Nevertheless, switching conditions between co- and counter-current flow lead to a favorable redistribution of biomass and elemental sulfur along the bed height. Moreover, elemental sulfur was oxidized to sulfate when the feeding biogas was disconnected and the supply of nitrate (electron acceptor) was maintained. Removal of elemental sulfur was important to prevent clogging in the packed bed and, thereby, to increase the lifespan of the packed bed between maintenance episodes. The larger elemental sulfur removal rate during shutdowns was 59.1 gS m(-3) h(-1). Tag-encoded FLX amplicon pyrosequencing was used to study the diversity of bacteria under co-current flow pattern with liquid recirculation and counter-current mode with a single-pass flow of the liquid phase. The main desulfurizing bacteria were Sedimenticola while significant role of heterotrophic, opportunistic species was envisaged. Remarkable differences between communities were found when a single-pass flow of industrial water was fed to the biotrickling filter. PMID:27231880

  11. Do in-line respiratory filters protect patients? Comparing bacterial removal efficiency of six filters.

    PubMed

    Canakis, Anne-Marie; Ho, Bernard; Ho, Sharon; Kovach, Danuta; Matlow, Anne; Coates, Allan L

    2002-11-01

    With all pulmonary function diagnostic and respiratory therapy equipment, cross-infection has always been a concern, especially in the cystic fibrosis population, in whom pulmonary function tests are done routinely. The aim of this study was to identify and compare the bacterial removal efficiency (BRE, ability of a filter to remove microorganisms) of six different filters used in hospital settings: Microgard (MG), Spirobac (SB), PALL (PL), and KOKO (KK), used in the pulmonary function laboratory; and Clear-Guard (CG) and Respigard (RG), used in ventilator circuits. Filters were tested in both saturated and nonsaturated conditions. A Pseudomonas aeruginosa suspension of 1 x 10(4) to 1 x 10(8) CFU/mL was nebulized onto each filter. A blood agar plate was held immediately downstream from the filter. Colony-forming units (CFU) were then counted after 24 hr of incubation. A peak flow was applied across the spirometry filters. Bacterial thresholds of the filters were also identified (concentration of bacteria at which a filter no longer has 100% BRE). There was a significant difference in BRE among the six filters in saturated states when challenged with 1 x 10(4) CFU/mL (MG, KK, CG, and RG, 100%; SB, 98.8%; PL, 42.7%; P = 0.003). There was no significant difference between saturated and nonsaturated states, or after application of a peak flow. Filter thresholds were significantly different (KK 1 x 10(8), MG 1 x 10(7), CG 1 x 10(6), RG 1 x 10(5), and SB and PL <1 x 10(4) CFU/mL). In conclusion, when all filters are exposed to the same extreme challenges, significant differences exist in their ability to remove bacteria. PMID:12357477

  12. Filter desulfation system and method

    DOEpatents

    Lowe, Michael D.; Robel, Wade J.; Verkiel, Maarten; Driscoll, James J.

    2010-08-10

    A method of removing sulfur from a filter system of an engine includes continuously passing an exhaust flow through a desulfation leg of the filter system during desulfation. The method also includes sensing at least one characteristic of the exhaust flow and modifying a flow rate of the exhaust flow during desulfation in response to the sensing.

  13. Exploring the velocity distribution of debris flows: An iteration algorithm based approach for complex cross-sections

    NASA Astrophysics Data System (ADS)

    Han, Zheng; Chen, Guangqi; Li, Yange; Wang, Wei; Zhang, Hong

    2015-07-01

    The estimation of debris-flow velocity in a cross-section is of primary importance due to its correlation to impact force, run up and superelevation. However, previous methods sometimes neglect the observed asymmetric velocity distribution, and consequently underestimate the debris-flow velocity. This paper presents a new approach for exploring the debris-flow velocity distribution in a cross-section. The presented approach uses an iteration algorithm based on the Riemann integral method to search an approximate solution to the unknown flow surface. The established laws for vertical velocity profile are compared and subsequently integrated to analyze the velocity distribution in the cross-section. The major benefit of the presented approach is that natural channels typically with irregular beds and superelevations can be taken into account, and the resulting approximation by the approach well replicates the direct integral solution. The approach is programmed in MATLAB environment, and the code is open to the public. A well-documented debris-flow event in Sichuan Province, China, is used to demonstrate the presented approach. Results show that the solutions of the flow surface and the mean velocity well reproduce the investigated results. Discussion regarding the model sensitivity and the source of errors concludes the paper.

  14. Discrete filters for large-eddy simulation of forced compressible magnetohydrodynamic turbulence

    NASA Astrophysics Data System (ADS)

    Chernyshov, A. A.; Petrosyan, A. S.

    2016-06-01

    We discuss results of the applicability of discrete filters for the large-eddy simulation (LES) method of forced compressible magnetohydrodynamic (MHD) turbulent flows with the scale-similarity model. New results are obtained for cross-helicity and residual energy. Cross-helicity and residual energy are important quantities in magnetohydrodynamic turbulence and have no hydrodynamic counterpart. The influences and effects of discrete filter shapes on the scale-similarity model are examined in physical space using finite-difference numerical schemes. We restrict ourselves to the Gaussian filter and the top-hat filter. Representations of this subgrid-scale model, which correspond to various 3- and 5-point approximations of both Gaussian and top-hat filters for different values of parameter ε (the ratio of the cut-off length-scale of the filter to the mesh size), are investigated. Discrete filters produce more discrepancies for the magnetic field. It is shown that the Gaussian filter is more sensitive to the parameter ɛ than the top-hat filter in compressible forced MHD turbulence. The 3-point filters at ε =2 and ε =3 give the least accurate results whereas the 5-point Gaussian filter shows the best results at ε =2 and ε =3. There are only very small differences deep into the dissipation region in favor of ε =2. For cross-helicity, the 5-point discrete filters are in good agreement with the results of direct numerical simulation (DNS), while the 3-point filter produces the largest discrepancies with DNS results. There is no strong dependence on the choice of the parameter ε and order approximation is a much more important factor for the cross-helicity. The difference between the filters is less for the residual energy compared with total energy. Thus, the total energy is more sensitive to the choice of discrete filter in the modeling of compressible MHD turbulence using the LES method.

  15. Cross-Roll Flow Forming of ODS Alloy Heat Exchanger Tubes for Hoop Creep Enhancement

    SciTech Connect

    Bimal K. Kad

    2006-04-10

    Mechanically alloyed oxide dispersion strengthened (ODS) Fe-Cr-Al alloy thin walled tubes and sheets, produced via powder processing and consolidation methodologies, are promising materials for eventual use at temperatures up to 1200 C in the power generation industry, far above the temperature capabilities of conventional alloys. Target end-uses range from gas turbine combustor liners to high aspect ratio (L/D) heat exchanger tubes. Grain boundary creep processes at service temperatures, particularly those acting in the hoop direction, are the dominant failure mechanisms for such components. The processed microstructure of ODS alloys consists of high aspect ratio grains aligned parallel to the tube axis, a result of dominant axial metal flow which aligns the dispersoid particles and other impurities in the longitudinal direction. The dispersion distribution is unaltered on a micro scale by recrystallization thermal treatments, but the high aspect ratio grain shape typically obtained limits transverse grain spacing and consequently the hoop creep response. Improving hoop creep in ODS-alloy components will require understanding and manipulating the factors that control the recrystallization behavior, and represents a critical materials design and development challenge that must be overcome in order to fully exploit the potential of ODS alloys. The objectives of this program are to (1) increase creep-strength at temperature in ODS-alloy tube and liner components by 100% via, (2) preferential cross-roll flow forming and grain/particle fibering in the critical hoop direction. The research program outlined here is iterative in nature and is intended to systematically (1) examine and identify post-extrusion forming methodologies to create hoop strengthened tubes, which will be (2) evaluated at ''in-service'' loads at service temperatures and environments. This research program is being conducted in collaboration with the DOE's Oak Ridge National Laboratory and the vested

  16. Summary of Flow Loss between Selected Cross Sections on the Rio Grande in and near Albuquerque, New Mexico

    USGS Publications Warehouse

    Veenhuis, Jack E.

    2002-01-01

    The upper middle Rio Grande Basin, as defined by the U.S. Army Corps of Engineers, extends from the headwaters of the Rio Grande in southwestern Colorado to Fort Quitman, Texas. Most of the basin has a semiarid climate typical of the southwestern United States. This climate drives a highly variable streamflow regime that contributes to the complexity of water management in the basin. Currently, rapid population growth in the basin has resulted in increasing demands on the hydrologic system. Water management decisions have become increasingly complex because of the broad range of interests and issues. For these reasons, the U.S. Geological Survey, in cooperation with the City of Albuquerque, New Mexico, conducted paired flow measurements at two cross sections to determine cross-sectional loss in the Albuquerque reach of the Rio Grande. This report statistically summarizes flow losses in the Albuquerque reach of the Rio Grande during the winter nonirrigation season from December 1996 to February 2000. The two previous flow-loss investigations are statistically summarized. Daily mean flow losses are calculated for the winter nonirrigation season using daily mean flows at three selected Rio Grande streamflow-gaging stations.For the winter nonirrigation season cross-sectional measurements (1996-2000), an average of 210 cubic feet per second was returned to the river between the measurement sites, of which 165 cubic feet per second was intercepted by riverside drains along the 21.9-mile reach from the Rio Grande near Bernalillo to the Rio Grande at Rio Bravo Bridge streamflow-gaging stations. Total cross-sectional losses in this reach averaged about 90 cubic feet per second. Regression equations were determined for estimating downstream total outflow from upstream total inflow for all three paired measurement studies. Regression equations relating the three daily mean flow recording stations also were determined. In each succeeding study, additional outside variables

  17. Water Filter

    NASA Technical Reports Server (NTRS)

    1982-01-01

    A compact, lightweight electrolytic water sterilizer available through Ambassador Marketing, generates silver ions in concentrations of 50 to 100 parts per billion in water flow system. The silver ions serve as an effective bactericide/deodorizer. Tap water passes through filtering element of silver that has been chemically plated onto activated carbon. The silver inhibits bacterial growth and the activated carbon removes objectionable tastes and odors caused by addition of chlorine and other chemicals in municipal water supply. The three models available are a kitchen unit, a "Tourister" unit for portable use while traveling and a refrigerator unit that attaches to the ice cube water line. A filter will treat 5,000 to 10,000 gallons of water.

  18. Investigation of the effect of gelatine, egg albumin and cross-flow microfiltration on the phenolic composition of Pinotage wine.

    PubMed

    Oberholster, A; Carstens, L M; du Toit, W J

    2013-06-01

    The effect of fining and cross-flow microfiltration on the phenolic composition of red wine was investigated. Both gelatine (G) and egg albumin (EA) fining decreased the mean degree of polymerisation (mDP) of tannin significantly by 26.4% and 25.2%, respectively, compared to the control (C). Cross-flow microfiltration (CF) also decreased the mDP significantly by 25%. Thus, the fining agents and cross-flow microfiltration selectively removed the highly polymerised phenols. After 3.5 months of bottle ageing, differences between the different treatments and the control decreased. CF had the most significant effect on the flavan-3-ol and polymeric phenol (tannin) content of the wines compared to the control followed by G fining. CF and EA treatments significantly decreased the total pigment content compared to C. CF was also the only treatment that could be distinguished from the other treatments by sensory analysis. All treatments improved clarity of the wines with cross-flow microfiltration having the largest effect. PMID:23411243

  19. Evaluation of the discrete vortex wake cross flow model using vector computers. Part 2: User's manual for DIVORCE

    NASA Technical Reports Server (NTRS)

    Deffenbaugh, F. D.; Vitz, J. F.

    1979-01-01

    The users manual for the Discrete Vortex Cross flow Evaluator (DIVORCE) computer program is presented. DIVORCE was developed in FORTRAN 4 for the DCD 6600 and CDC 7600 machines. Optimal calls to a NASA vector subroutine package are provided for use with the CDC 7600.

  20. Experimental Study of an Inclined Jet-In-Cross-Flow Interacting with a Vortex Generator

    NASA Technical Reports Server (NTRS)

    Zaman, K. B. M. Q.; Rigby, D. L.; Heidmann, J. D.

    2010-01-01

    An experiment is conducted on the effectiveness of a vortex generator (VG) in preventing lift-off of a jet-in-cross-flow (JICF), with film-cooling application in mind. The jet issues into the boundary layer at an angle of 20 to the free-stream. The effect of a triangular ramp-shaped VG is studied while varying its geometry and location. Detailed flow-field properties are documented for a specific case in which the height of the VG and the diameter of the orifice are comparable to the approach boundary layer thickness. This combination of VG and JICF produce a streamwise vortex pair with vorticity magnitude three times larger (and of opposite sense) than that found in the JICF alone. Such a VG appears to be most effective in keeping the jet attached to the wall. While most of the data are taken at a jet-to-freestream momentum flux ratio (J) of 2, limited surveys are done for varying J. The VG is found to have a significant effect even at the highest J (=11) covered in the experiment. Effect of parametric variation is studied mostly from surveys ten diameters downstream from the orifice. When the VG height is halved there is a lift-off of the jet. On the other hand, when the height is doubled, the jet core is dissipated due to larger turbulence intensities. Varying the location of the VG, over a distance of three diameters from the orifice, is found to have little impact. Rounding off the edges of the VG with increasing radius of curvature progressively diminishes the effect. However, a small radius of curvature may be quite tolerable in practice.

  1. Application and advantages of novel clay ceramic particles (CCPs) in an up-flow anaerobic bio-filter (UAF) for wastewater treatment.

    PubMed

    Han, Wei; Yue, Qinyan; Wu, Suqing; Zhao, Yaqin; Gao, Baoyu; Li, Qian; Wang, Yan

    2013-06-01

    Utilization of clay ceramic particles (CCPs) as the novel filter media employed in an up-flow anaerobic bio-filter (UAF) was investigated. After a series of tests and operations, CCPs have presented higher total porosity and roughness, meanwhile lower bulk and grain density. When CCPs were utilized as fillers, the reactor had a shorter start up period of 45 days comparing with conventional reactors, and removal rate of chemical oxygen demand (COD) still reached about 76% at a relatively lower temperature during the stable state. In addition, degradation of COD and ammonia nitrogen (NH4-N) at different media height along the reactor was evaluated, and the dates showed that the main reduction process happened within the first 30 cm media height from the bottom flange. Five phases were observed according to different organic loadings during the experiment period, and the results indicated that COD removal increased linearly when the organic loading was increased.

  2. Removal of phenol from coke-oven wastewater by cross-flow nanofiltration membranes.

    PubMed

    Kumar, Ramesh; Pal, Parimal

    2013-05-01

    This study investigated the phenol rejection characteristics of some nanofiltration membranes during treatment of coke wastewater. Four different types of composite polyamide commercial nanofiltration membranes (Sepro, USA) were tested under different operating conditions including transmembrane pressure, pH and recovery rate. When pressure was increased from 4 to 16 bars, the percentage of rejection of phenol in the permeate increased from 72.5% to 97.7% while yielding a high flux of 118 litres per square meter per hour(LMH) at a volumetric cross flow rate of 800 litres per hour at pH 10 (in recirculation mode) in case of NF1 membrane. The effect of recovery rate on the rejection coefficient of phenol and flux was also studied in concentrated mode and found that a recovery rate of up 55% nanofiltration was successfully operated without much decline of flux and rejection coefficient. Finally, nanofiltration had great efficiency in phenol removal from industrial wastewater and was considered suitable regarding its operation.

  3. Cyanide removal from industrial wastewater by cross-flow nanofiltration: transport modeling and economic evaluation.

    PubMed

    Pal, Parimal; Bhakta, Pamela; Kumar, Ramesh

    2014-08-01

    A modeling and simulation study, along with an economic analysis, was carried out for the separation of cyanide from industrial wastewater using a flat sheet cross-flow nanofiltration membrane module. With the addition of a pre-microfiltration step, nanofiltration was carried out using real coke wastewater under different operating conditions. Under the optimum operating pressure of 13 bars and a pH of 10.0, a rate of more than 95% separation of cyanide was achieved. That model predictions agreed very well with the experimental findings, as is evident in the Willmott d-index value (> 0.95) and relative error (< 0.1). Studies were carried out with industrial wastewater instead of a synthetic solution, and an economic analysis was also done, considering the capacity of a running coking plant. The findings are likely to be very useful in the scale-up and design of industrial plants for the treatment of cyanide-bearing wastewater. PMID:25306785

  4. Turbulent flow in pipes and channels as cross-stream ``inverse cascades'' of vorticity

    NASA Astrophysics Data System (ADS)

    Eyink, Gregory L.

    2008-12-01

    A commonplace view of pressure-driven turbulence in pipes and channels is as "cascades" of streamwise momentum toward the viscous layer at the wall. We present in this paper an alternative picture of these flows as "inverse cascades" of spanwise vorticity in the cross-stream direction but away from the viscous sublayer. We show that there is a constant spatial flux of spanwise vorticity due to vorticity conservation and that this flux is necessary to produce pressure drop and energy dissipation. The vorticity transport is shown to be dominated by viscous diffusion at distances closer to the wall than the peak Reynolds stress, well into the classical log layer. The Perry-Chong model based on "representative" hairpin/horseshoe vortices predicts a single sign of the turbulent vorticity flux over the whole log layer, whereas the actual flux must change sign at the location of the Reynolds-stress maximum. Sign reversal may be achieved by assuming a slow power-law decay of the Townsend "eddy-intensity function" for wall-normal distances greater than the hairpin length scale. The vortex-cascade picture presented here has a close analog in the theory of quantum superfluids and superconductors, the "phase slippage" of quantized vortex lines. Most of our results should therefore apply as well to superfluid turbulence in pipes and channels. We also discuss issues about drag reduction from this perspective.

  5. Carotenoids concentration of Gac (Momordica cochinchinensis Spreng.) fruit oil using cross-flow filtration technology.

    PubMed

    Mai, Huỳnh Cang; Truong, Vinh; Debaste, Frédéric

    2014-11-01

    Gac (Momordica cochinchinensis Spreng.) fruit, a traditional fruit in Vietnam and other countries of eastern Asia, contains an oil rich in carotenoids, especially lycopene and β-carotene. Carotenoids in gac fruit oil were concentrated using cross-flow filtration. In total recycle mode, effect of membrane pore size, temperature, and transmembrane pressure (TMP) on permeate flux and on retention coefficients has been exploited. Resistance of membrane, polarization concentration, and fouling were also analyzed. Optimum conditions for a high permeate flux and a good carotenoids retention are 5 nm, 2 bars, and 40 °C of membrane pore size, TMP, and temperature, respectively. In batch mode, retentate was analyzed through index of acid, phospholipids, total carotenoids content (TCC), total antioxidant activity, total soluble solids, total solid content, color measurement, and viscosity. TCC in retentate is higher 8.6 times than that in feeding oil. Lipophilic antioxidant activities increase 6.8 times, while hydrophilic antioxidant activities reduce 40%. The major part of total resistance is due to polarization (55%) while fouling and intrinsic membrane contribute about 30% and 24%, respectively. PMID:25367308

  6. Cross-flow microfiltration for lab-on-chip defatting of human breast milk

    NASA Astrophysics Data System (ADS)

    Lai, Meifang; Lai, Ching Tat; Keating, Adrian; Dell, John; Liu, Yinong

    2008-12-01

    Determining the lactose concentration in human breast milk (HBM) via standard assay techniques requires fat removal from the milk (defatting), followed by lactose detection in the remaining skim milk. This work focuses on methods of defatting which can be subsequently integrated in the same Lab-on-Chip (LOC) as the lactose measurement. One method under study for defatting HBM is the use of a cross-flow microfiltration structure. This kind of microfiltration prevents clogging and separates the large fat globules from the smaller nutrition constituents of milk, of which lactose is amongst the smallest. To test if large fat globules may clog the channel or not, the biocompatibility of PMMA and HBM was studied. The weight of absorbed fat on the surface of PMMA was found to be 3-orders of magnitude lower than that of the total fat in HBM. Photolithgraphy using SU-8 was applied for mold fabrication; however, hot-embossing using SU-8 mold has not been successful due to the high stress resulting in the demolding process. To improve mold strength, nickel molds were fabricated by electroplating using different current densities. As expected, the deposition rates were found to have a linear relationship with applied current density, while the smaller features have a higher deposition rate than larger features.

  7. Optimization of circular plate separators with cross flow for removal of oil droplets and solid particles.

    PubMed

    Ngu, Hei; Wong, Kien Kuok; Law, Puong Ling

    2012-04-01

    A circular gravity-phase separator using coalescing medium with cross flow was developed to remove oil and suspended solids from wastewaters. Coalescence medium in the form of inclined plates promotes rising of oil droplets through coalescence and settling of solid particles through coagulation. It exhibits 22.67% higher removal of total suspended solids (TSS) compared to separators without coalescing medium. Moreover, it removed more than 70% of oil compared to conventional American Petroleum Institute separators, which exhibit an average of 33% oil removal. The flowrate required to attain an effluent oil concentration of 10 mg/L (Q(o10)) at different influent oil concentrations (C(io)) can be represented by Q(o10) x 10(-5) = -0.0012C(io) + 0.352. The flowrate required to attain an effluent TSS concentration of 50 mg/L (Q(ss50)) at different influent TSS concentrations (C(iss)) can be represented by Q(ss50) x 10(-5) = 1.0 x 10(6) C(iss)(-2.9576). The smallest removable solid particle size was 4.87 microm. PMID:22834217

  8. Three-Dimensionally Printed Microfluidic Cross-flow System for Ultrafiltration/Nanofiltration Membrane Performance Testing.

    PubMed

    Wardrip, Nathaniel C; Arnusch, Christopher J

    2016-01-01

    Minimization and management of membrane fouling is a formidable challenge in diverse industrial processes and other practices that utilize membrane technology. Understanding the fouling process could lead to optimization and higher efficiency of membrane based filtration. Here we show the design and fabrication of an automated three-dimensionally (3-D) printed microfluidic cross-flow filtration system that can test up to 4 membranes in parallel. The microfluidic cells were printed using multi-material photopolymer 3-D printing technology, which used a transparent hard polymer for the microfluidic cell body and incorporated a thin rubber-like polymer layer, which prevents leakages during operation. The performance of ultrafiltration (UF), and nanofiltration (NF) membranes were tested and membrane fouling could be observed with a model foulant bovine serum albumin (BSA). Feed solutions containing BSA showed flux decline of the membrane. This protocol may be extended to measure fouling or biofouling with many other organic, inorganic or microbial containing solutions. The microfluidic design is especially advantageous for testing materials that are costly or only available in small quantities, for example polysaccharides, proteins, or lipids due to the small surface area of the membrane being tested. This modular system may also be easily expanded for high throughput testing of membranes.

  9. Three-Dimensionally Printed Microfluidic Cross-flow System for Ultrafiltration/Nanofiltration Membrane Performance Testing.

    PubMed

    Wardrip, Nathaniel C; Arnusch, Christopher J

    2016-01-01

    Minimization and management of membrane fouling is a formidable challenge in diverse industrial processes and other practices that utilize membrane technology. Understanding the fouling process could lead to optimization and higher efficiency of membrane based filtration. Here we show the design and fabrication of an automated three-dimensionally (3-D) printed microfluidic cross-flow filtration system that can test up to 4 membranes in parallel. The microfluidic cells were printed using multi-material photopolymer 3-D printing technology, which used a transparent hard polymer for the microfluidic cell body and incorporated a thin rubber-like polymer layer, which prevents leakages during operation. The performance of ultrafiltration (UF), and nanofiltration (NF) membranes were tested and membrane fouling could be observed with a model foulant bovine serum albumin (BSA). Feed solutions containing BSA showed flux decline of the membrane. This protocol may be extended to measure fouling or biofouling with many other organic, inorganic or microbial containing solutions. The microfluidic design is especially advantageous for testing materials that are costly or only available in small quantities, for example polysaccharides, proteins, or lipids due to the small surface area of the membrane being tested. This modular system may also be easily expanded for high throughput testing of membranes. PMID:26968008

  10. Performance of a cross-flow humidifier with a high flux water vapor transport membrane

    NASA Astrophysics Data System (ADS)

    Ahluwalia, R. K.; Wang, X.; Johnson, W. B.; Berg, F.; Kadylak, D.

    2015-09-01

    Water vapor transport (WVT) flux across a composite membrane that consists of a very thin perfluorosulfonic acid (PFSA) ionomer layer sandwiched between two expanded polytetrafluoroethylene (PTFE) microporous layers is investigated. Static and dynamic tests are conducted to measure WVT flux for different composite structures; a transport model shows that the underlying individual resistances for water diffusion in the gas phase and microporous and ionomer layers and for interfacial kinetics of water uptake at the ionomer surface are equally important under different conditions. A finite-difference model is formulated to determine water transport in a full-scale (2-m2 active membrane area) planar cross-flow humidifier module assembled using pleats of the optimized composite membrane. In agreement with the experimental data, the modeled WVT flux in the module increases at higher inlet relative humidity (RH) of the wet stream and at lower pressures, but the mass transfer effectiveness is higher at higher pressures. The model indicates that the WVT flux is highest under conditions that maintain the wet stream at close to 100% RH while preventing the dry stream from becoming saturated. The overall water transport is determined by the gradient in RH of the wet and dry streams but is also affected by vapor diffusion in the gas layer and the microporous layer.

  11. Route optimisation and solving Zermelo's navigation problem during long distance migration in cross flows.

    PubMed

    Hays, Graeme C; Christensen, Asbjørn; Fossette, Sabrina; Schofield, Gail; Talbot, Julian; Mariani, Patrizio

    2014-02-01

    The optimum path to follow when subjected to cross flows was first considered over 80 years ago by the German mathematician Ernst Zermelo, in the context of a boat being displaced by ocean currents, and has become known as the 'Zermelo navigation problem'. However, the ability of migrating animals to solve this problem has received limited consideration, even though wind and ocean currents cause the lateral displacement of flyers and swimmers, respectively, particularly during long-distance journeys of 1000s of kilometres. Here, we examine this problem by combining long-distance, open-ocean marine turtle movements (obtained via long-term GPS tracking of sea turtles moving 1000s of km), with a high resolution basin-wide physical ocean model to estimate ocean currents. We provide a robust mathematical framework to demonstrate that, while turtles eventually arrive at their target site, they do not follow the optimum (Zermelo's) route. Even though adult marine turtles regularly complete incredible long-distance migrations, these vertebrates primarily rely on course corrections when entering neritic waters during the final stages of migration. Our work introduces a new perspective in the analysis of wildlife tracking datasets, with different animal groups potentially exhibiting different levels of complexity in goal attainment during migration. PMID:24304813

  12. Carotenoids concentration of Gac (Momordica cochinchinensis Spreng.) fruit oil using cross-flow filtration technology.

    PubMed

    Mai, Huỳnh Cang; Truong, Vinh; Debaste, Frédéric

    2014-11-01

    Gac (Momordica cochinchinensis Spreng.) fruit, a traditional fruit in Vietnam and other countries of eastern Asia, contains an oil rich in carotenoids, especially lycopene and β-carotene. Carotenoids in gac fruit oil were concentrated using cross-flow filtration. In total recycle mode, effect of membrane pore size, temperature, and transmembrane pressure (TMP) on permeate flux and on retention coefficients has been exploited. Resistance of membrane, polarization concentration, and fouling were also analyzed. Optimum conditions for a high permeate flux and a good carotenoids retention are 5 nm, 2 bars, and 40 °C of membrane pore size, TMP, and temperature, respectively. In batch mode, retentate was analyzed through index of acid, phospholipids, total carotenoids content (TCC), total antioxidant activity, total soluble solids, total solid content, color measurement, and viscosity. TCC in retentate is higher 8.6 times than that in feeding oil. Lipophilic antioxidant activities increase 6.8 times, while hydrophilic antioxidant activities reduce 40%. The major part of total resistance is due to polarization (55%) while fouling and intrinsic membrane contribute about 30% and 24%, respectively.

  13. Removal of phenol from coke-oven wastewater by cross-flow nanofiltration membranes.

    PubMed

    Kumar, Ramesh; Pal, Parimal

    2013-05-01

    This study investigated the phenol rejection characteristics of some nanofiltration membranes during treatment of coke wastewater. Four different types of composite polyamide commercial nanofiltration membranes (Sepro, USA) were tested under different operating conditions including transmembrane pressure, pH and recovery rate. When pressure was increased from 4 to 16 bars, the percentage of rejection of phenol in the permeate increased from 72.5% to 97.7% while yielding a high flux of 118 litres per square meter per hour(LMH) at a volumetric cross flow rate of 800 litres per hour at pH 10 (in recirculation mode) in case of NF1 membrane. The effect of recovery rate on the rejection coefficient of phenol and flux was also studied in concentrated mode and found that a recovery rate of up 55% nanofiltration was successfully operated without much decline of flux and rejection coefficient. Finally, nanofiltration had great efficiency in phenol removal from industrial wastewater and was considered suitable regarding its operation. PMID:23789574

  14. Inexpensive cross-flow hydropower turbine at Arbuckle Mountain Hydroelectric Project

    SciTech Connect

    Not Available

    1991-07-01

    This report documents the first three and half years of operation and maintenance on the Arbuckle Mountain Hydroelectric Project. Located on a flashy mountain stream in northern California, the project was designed, built and tested through a Cooperative Agreement between the US DOE and OTT Engineering, Inc. (OTT). The purpose of the Agreement is to build and intensively test an inexpensive American-made cross-flow turbine and to provide information to the DOE on the cost, efficiency, operation, and maintenance of the unit. It requires that OTT document for DOE a summary of the complete operating statistics, operation and maintenance cost, and revenues from power sales for a two-year operating period. Several unique events occurred between the initial start-up (December 1986) and the beginning of the 1989 generation season (October 1988) that delayed the first year's full operation and provided unique information for a demonstration project of this type. Accordingly, this report will discuss certain major problems experienced with the design, operation and maintenance, and energy production, as well as the operation and maintenance costs and value of the power produced for the first three and half years of operation. 9 figs., 2 tabs.

  15. Performance of a Cross-Flow Humidifier with a High Flux Water Vapor Transport Membrane

    SciTech Connect

    Ahluwalia, R. K.; Wang, X.; Johnson, W. B.; Berg, F.; Kadylak, D.

    2015-09-30

    Water vapor transport (WVT) flux across a composite membrane that consists of a very thin perfluorosulfonic acid (PFSA) ionomer layer sandwiched between two expanded polytetrafluoroethylene (PTFE) microporous layers is investigated. Static and dynamic tests are conducted to measure WVT flux for different composite structures; a transport model shows that the underlying individual resistances for water diffusion in the gas phase and microporous and ionomer layers and for interfacial kinetics of water uptake at the ionomer surface are equally important under different conditions. A finite-difference model is formulated to determine water transport in a full-scale (2-m2 active membrane area) planar cross-flow humidifier module assembled using pleats of the optimized composite membrane. In agreement with the experimental data, the modeled WVT flux in the module increases at higher inlet relative humidity (RH) of the wet stream and at lower pressures, but the mass transfer effectiveness is higher at higher pressures. The model indicates that the WVT flux is highest under conditions that maintain the wet stream at close to 100% RH while preventing the dry stream from becoming saturated. The overall water transport is determined by the gradient in RH of the wet and dry streams but is also affected by vapor diffusion in the gas layer and the microporous layer.

  16. Innovative cross-flow membrane system for volume reduction of mixed waste

    SciTech Connect

    Greene, W.

    1997-10-01

    In this task, SpinTek Membrane Systems, Inc., and the Institute of Gas Technology are completing engineering development leading to a full-scale demonstration of the SpinTek ST-II High Shear Rotary Membrane Filtration System (ST-II) under a Program Research and Development Agreement (PRDA) with the Federal Energy Technology Center-Morgantown. The SpinTek ST-II technology will be scaled-up, and a two-stage ST-II system will be designed, constructed, and operated on both surrogate and actual feed at the Los Alamos National Laboratory (LANL) Liquid Radioactive Waste Treatment Facility (LRWTF). Results from these studies on both surrogate and actual wastewater streams will also be used by LANL personnel to produce a model for determining the applicability and economics of the SpinTek ST-II system to other DOE waste and process streams. The ST-II is a unique, compact cross-flow membrane system having several advantages in performance and cost compared to currently available systems. Staff at LANL have performed pilot-scale testing with the SpinTek technology to evaluate its feasibility for enhanced radionuclide removal from wastewater at its 5- to 8-million-gallon-per-year LRWTF. Recent data have shown the system`s capabilities to remove radionuclides from the waste stream at concentration factors greater than 2000:1, and performance has exceeded both conventional and all other advanced technologies examined.

  17. Electrohydrodynamic flow through a 1 mm(2) cross-section pore placed in an ion-exchange membrane.

    PubMed

    Doi, Kentaro; Yano, Ayako; Kawano, Satoyuki

    2015-01-01

    In recent years, the control of ionic currents has come to be recognized as one of the most important issues related to the efficient transport of single molecules and microparticles in aqueous solutions. However, the complicated liquid flows that are usually induced by applying electric potentials have made it difficult to address a number of unsolved problems in this area. In particular, the nonequilibrium phenomena that occur in electrically non-neutral fields must be more thoroughly understood. Herein, we report on the development of a theoretical model of liquid flows resulting from ion interactions while focusing on the so-called electrohydrodynamic (EHD) flow. We also discuss the development of an experimental system to optically and electrically observe EHD flows using a 1 mm(2) cross-section pore placed in an ion-exchange membrane where cation and anion flows can be separated without the use of a charged environment. Although micro/nanosized flow channels are usually applied to induce electric double layer overlaps to utilize strong electroosmotic effects, our system does not require such laborious fabrication processes. Instead, we visualize EHD flows by using a millimeter size pore immersed in an alkaline aqueous solution. In this setup, liquid flows passing through the pore along the direction of ion flow, whose velocity reaches on the order of 1 mm/s, can be clearly observed by applying a few volts of electric potential. Furthermore, the transient phenomena associated with ionic responses are theoretically elucidated.

  18. Numerical heat and mass transfer analysis of a cross-flow indirect evaporative cooler with plates and flat tubes

    NASA Astrophysics Data System (ADS)

    Chua, K. J.; Xu, J.; Cui, X.; Ng, K. C.; Islam, M. R.

    2016-09-01

    In this study the performance of an indirect evaporative cooling system (IECS) of cross-flow configuration is numerically investigated. Considering the variation of water film temperature along the flowing path and the wettability of the wet channel, a two-dimensional theoretical model is developed to comprehensively describe the heat and mass transfer process involved in the system. After comparing the simulation results with available experimental data from literature, the deviation within ±5 % proves the accuracy and reliability of the proposed mathematical model. The simulation results of the plate type IECS indicate that the important parameters, such as dimension of plates, air properties, and surface wettability play a great effect on the cooling performance. The investigation of flow pattern shows that cross-flow configuration of primary air with counter-flow of secondary air and water film has a better cooling performance than that of the parallel-flow pattern. Furthermore, the performance of a novel flat tube working as the separating medium is numerically investigated. Simulation results for this novel geometry indicate that the tube number, tube long axis and short axis length as well as tube length remarkably affect its cooling performance.

  19. Remotely serviced filter and housing

    DOEpatents

    Ross, Maurice J.; Zaladonis, Larry A.

    1988-09-27

    A filter system for a hot cell comprises a housing adapted for input of air or other gas to be filtered, flow of the air through a filter element, and exit of filtered air. The housing is tapered at the top to make it easy to insert a filter cartridge using an overhead crane. The filter cartridge holds the filter element while the air or other gas is passed through the filter element. Captive bolts in trunnion nuts are readily operated by electromechanical manipulators operating power wrenches to secure and release the filter cartridge. The filter cartridge is adapted to make it easy to change a filter element by using a master-slave manipulator at a shielded window station.

  20. Hyporheic flow, solute transport, and heat flux in the stream bed around cross-vane restoration structures

    NASA Astrophysics Data System (ADS)

    Gordon, Ryan; Lautz, Laura; Daniluk, Timothy

    2010-05-01

    Natural channel design restoration projects in streams often include cross-vanes, which are low, stone, dam-like structures that span the active channel. The change in water elevation over a cross-vane decreases the static pressure head across the structure from upstream to downstream. It is hypothesized that, as a result, a cross-vane increases the local hyporheic exchange of water through the stream bed. Stream beds are the permeable interface between surface water in streams and groundwater in fluvial aquifers. The hyporheic zone includes the area of the bed where water from the active channel mixes with pore water in shallow sediments and returns to the channel. Channel forms, such as steps, pools, and riffles, intensify the flux of water through the hyporheic zone. Flow paths that redirect stream water through the hyporheic zone increase the residence time of dissolved oxygen, organic material, and nutrients in the stream bed, where enhanced geochemical and biological processes alter the water chemistry and create distinct gradients of redox-sensitive solutes. Hyporheic exchange therefore influences surface water quality, and impacts the health of aquatic species and ecosystems. Few studies have investigated the impact of static restoration structures on hyporheic exchange fluxes or water chemistry. Here we present the results of an investigation of hyporheic flow, solute transport, and heat flux at the locations of two cross-vanes and one natural riffle in a second-order stream in central New York State, USA. Pore water temperatures and water samples from the stream bed were collected in a meter-scale grid at 20-cm depth surrounding the structures and riffle. Temperature was also recorded every 10 minutes for over 2 weeks at several different depths at a subset of points at each site. The time-series temperature data and meter-scale grid temperature measurements were used to calculate vertical water flux rates using an analytical heat transport model. Water

  1. Standardizing admission and discharge processes to improve patient flow: A cross sectional study

    PubMed Central

    2012-01-01

    Background The aim of this study was to evaluate how hospital capacity was managed focusing on standardizing the admission and discharge processes. Methods This study was set in a 900-bed university affiliated hospital of the National Health Service, near Barcelona (Spain). This is a cross-sectional study of a set of interventions which were gradually implemented between April and December 2008. Mainly, they were focused on standardizing the admission and discharge processes to improve patient flow. Primary administrative data was obtained from the 2007 and 2009 Hospital Database. Main outcome measures were median length of stay, percentage of planned discharges, number of surgery cancellations and median number of delayed emergency admissions at 8:00 am. For statistical bivariate analysis, we used a Chi-squared for linear trend for qualitative variables and a Wilcoxon signed ranks test and a Mann–Whitney test for non-normal continuous variables. Results The median patients’ global length of stay was 8.56 days in 2007 and 7.93 days in 2009 (p < 0.051). The percentage of patients admitted the same day as surgery increased from 64.87% in 2007 to 86.01% in 2009 (p < 0.05). The number of cancelled interventions due to lack of beds was 216 patients in 2007 and 42 patients in 2009. The median number of planned discharges went from 43.05% in 2007 to 86.01% in 2009 (p < 0.01). The median number of emergency patients waiting for an in-hospital bed at 8:00 am was 5 patients in 2007 and 3 patients in 2009 (p < 0.01). Conclusions In conclusion, standardization of admission and discharge processes are largely in our control. There is a significant opportunity to create important benefits for increasing bed capacity and hospital throughput. PMID:22741542

  2. Experimental Study of a Reference Model Vertical-Axis Cross-Flow Turbine

    PubMed Central

    Wosnik, Martin; Gunawan, Budi; Neary, Vincent S.

    2016-01-01

    The mechanical power, total rotor drag, and near-wake velocity of a 1:6 scale model (1.075 m diameter) of the US Department of Energy’s Reference Model vertical-axis cross-flow turbine were measured experimentally in a towing tank, to provide a comprehensive open dataset for validating numerical models. Performance was measured for a range of tip speed ratios and at multiple Reynolds numbers by varying the rotor’s angular velocity and tow carriage speed, respectively. A peak power coefficient CP = 0.37 and rotor drag coefficient CD = 0.84 were observed at a tip speed ratio λ0 = 3.1. A regime of weak linear Re-dependence of the power coefficient was observed above a turbine diameter Reynolds number ReD ≈ 106. The effects of support strut drag on turbine performance were investigated by covering the rotor’s NACA 0021 struts with cylinders. As expected, this modification drastically reduced the rotor power coefficient. Strut drag losses were also measured for the NACA 0021 and cylindrical configurations with the rotor blades removed. For λ = λ0, wake velocity was measured at 1 m (x/D = 0.93) downstream. Mean velocity, turbulence kinetic energy, and mean kinetic energy transport were compared with results from a high solidity turbine acquired with the same test apparatus. Like the high solidity case, mean vertical advection was calculated to be the largest contributor to near-wake recovery. However, overall, lower levels of streamwise wake recovery were calculated for the RM2 case—a consequence of both the relatively low solidity and tapered blades reducing blade tip vortex shedding—responsible for mean vertical advection—and lower levels of turbulence caused by higher operating tip speed ratio and therefore reduced dynamic stall. Datasets, code for processing and visualization, and a CAD model of the turbine have been made publicly available. PMID:27684076

  3. Filters for cathodic arc plasmas

    DOEpatents

    Anders, Andre; MacGill, Robert A.; Bilek, Marcela M. M.; Brown, Ian G.

    2002-01-01

    Cathodic arc plasmas are contaminated with macroparticles. A variety of magnetic plasma filters has been used with various success in removing the macroparticles from the plasma. An open-architecture, bent solenoid filter, with additional field coils at the filter entrance and exit, improves macroparticle filtering. In particular, a double-bent filter that is twisted out of plane forms a very compact and efficient filter. The coil turns further have a flat cross-section to promote macroparticle reflection out of the filter volume. An output conditioning system formed of an expander coil, a straightener coil, and a homogenizer, may be used with the magnetic filter for expanding the filtered plasma beam to cover a larger area of the target. A cathodic arc plasma deposition system using this filter can be used for the deposition of ultrathin amorphous hard carbon (a-C) films for the magnetic storage industry.

  4. An experimental study of fluidelastic instability and draf force on a tube in two-phase cross flow

    SciTech Connect

    Joo, Youngcheol

    1994-12-31

    Two-phase cross flow over heat exchanger tubes creates vibrations which contribute greatly to the wear on the tubes. Fluidelastic instability is a major mechanism by which tubes can fail. In this work, the fluidelastic instability of a tube placed in an array subjected to two-phase cross flow has been studied. For the determination of fluidelastic instability, a triangular tube array was used. The tubes were made of acrylic and were 2.2 cm or 2.37 cm in diameter and 20 cm in length. Eighteen tubes and 4 half tubes formed 5 rows with a pitch to diameter ratio of 1.4. All of the tubes except the test tube were rigidly supported at the text section wall. The test tube was flexibly supported with two cantilever beams. By installing cantilever beams horizontally and vertically, drag and lift direction tube vibration were studied. Parameters of tube mass, structural stiffness, natural frequency, and pitch to diameter ratio were varied. The drag coefficients on a rigidly held tube in an array subjected to two-phase cross flow were measured. The tube in an array was located at displaced positions as well as at the normal position in order to study the variation of fluid force as the tube vibrates. In the experiments, gap Reynolds numbers up to 1 x 10{sup 5} were obtained, while void fraction was varied from zero to 0.5. The drag coefficients in two-phase flow are much higher than those in single phase flow. The ratio of two-phase to single phase drag coefficient decreases as Reynolds number increases. The drag coefficient on a tube in an array increases as the tube is displaced in the direction of flow. The drag coefficient increases rapidly when the tube is displaced more than a certain critical distance.

  5. Surface and flow field measurements in a symmetric crossing shock wave/turbulent boundary-layer interaction

    NASA Technical Reports Server (NTRS)

    Davis, D. O.; Hingst, W. R.

    1992-01-01

    Results of an experimental investigation of a symmetric crossing shock/turbulent boundary layer interaction are presented for a Mach number of 3.44 and deflection angles of 2, 6, 8, and 9 degrees. The interaction strengths vary from weak to strong enough to cause a large region of separated flow. Measured quantities include surface static pressure (both steady and unsteady) and flowfield Pitot pressures. Pitot profiles in the plane of symmetry through the interaction region are shown for various deflection angles. Oil flow visualization and the results of a trace gas streamline tracking technique are also presented.

  6. Numerical simulation of ground-water flow in La Crosse County, Wisconsin, and into nearby pools of the Mississippi River

    USGS Publications Warehouse

    Hunt, Randall J.; Saad, David A.; Chapel, Dawn M.

    2003-01-01

    The models provide estimates of the locations and amount of ground-water flow into Pool 8 and the southern portion of Pool 7 of the Mississippi River. Ground-water discharges into all areas of the pools, except along the eastern shore in the vicinity of the city of La Crosse and immediately downgradient from lock and dam 7 and 8. Ground-water flow into the pools is generally greatest around the perimeter with decreasing amounts away from the perimeter. An area of relatively high ground-water discharge extends out towards the center of Pool 7 from the upper reaches of the pool and may

  7. Filter construction and design.

    PubMed

    Jornitz, Maik W

    2006-01-01

    Sterilizing and pre-filters are manufactured in different formats and designs. The criteria for the specific designs are set by the application and the specifications of the filter user. The optimal filter unit or even system requires evaluation, such as flow rate, throughput, unspecific adsorption, steam sterilizability and chemical compatibility. These parameters are commonly tested within a qualification phase, which ensures that an optimal filter design and combination finds its use. If such design investigations are neglected it could be costly in the process scale. PMID:16570863

  8. Novel Backup Filter Device for Candle Filters

    SciTech Connect

    Bishop, B.; Goldsmith, R.; Dunham, G.; Henderson, A.

    2002-09-18

    The currently preferred means of particulate removal from process or combustion gas generated by advanced coal-based power production processes is filtration with candle filters. However, candle filters have not shown the requisite reliability to be commercially viable for hot gas clean up for either integrated gasifier combined cycle (IGCC) or pressurized fluid bed combustion (PFBC) processes. Even a single candle failure can lead to unacceptable ash breakthrough, which can result in (a) damage to highly sensitive and expensive downstream equipment, (b) unacceptably low system on-stream factor, and (c) unplanned outages. The U.S. Department of Energy (DOE) has recognized the need to have fail-safe devices installed within or downstream from candle filters. In addition to CeraMem, DOE has contracted with Siemens-Westinghouse, the Energy & Environmental Research Center (EERC) at the University of North Dakota, and the Southern Research Institute (SRI) to develop novel fail-safe devices. Siemens-Westinghouse is evaluating honeycomb-based filter devices on the clean-side of the candle filter that can operate up to 870 C. The EERC is developing a highly porous ceramic disk with a sticky yet temperature-stable coating that will trap dust in the event of filter failure. SRI is developing the Full-Flow Mechanical Safeguard Device that provides a positive seal for the candle filter. Operation of the SRI device is triggered by the higher-than-normal gas flow from a broken candle. The CeraMem approach is similar to that of Siemens-Westinghouse and involves the development of honeycomb-based filters that operate on the clean-side of a candle filter. The overall objective of this project is to fabricate and test silicon carbide-based honeycomb failsafe filters for protection of downstream equipment in advanced coal conversion processes. The fail-safe filter, installed directly downstream of a candle filter, should have the capability for stopping essentially all particulate

  9. Cross-borehole flow analysis to characterize fracture connections in the Melechov Granite, Bohemian-Moravian Highland, Czech Republic

    USGS Publications Warehouse

    Paillet, Frederick L.; Williams, John H.; Urik, Joseph; Lukes, Joseph; Kobr, Miroslav; Mares, Stanislav

    2012-01-01

    Application of the cross-borehole flow method, in which short pumping cycles in one borehole are used to induce time-transient flow in another borehole, demonstrated that a simple hydraulic model can characterize the fracture connections in the bedrock mass between the two boreholes. The analysis determines the properties of fracture connections rather than those of individual fractures intersecting a single borehole; the model contains a limited number of adjustable parameters so that any correlation between measured and simulated flow test data is significant. The test was conducted in two 200-m deep boreholes spaced 21 m apart in the Melechov Granite in the Bohemian-Moravian Highland, Czech Republic. Transient flow was measured at depth stations between the identified transmissive fractures in one of the boreholes during short-term pumping and recovery periods in the other borehole. Simulated flows, based on simple model geometries, closely matched the measured flows. The relative transmissivity and storage of the inferred fracture connections were corroborated by tracer testing. The results demonstrate that it is possible to assess the properties of a fracture flow network despite being restricted to making measurements in boreholes in which a local population of discrete fractures regulates the hydraulic communication with the larger-scale aquifer system.

  10. Elimination of motion, pulsatile flow and cross-talk artifacts using blade sequences in lumbar spine MR imaging.

    PubMed

    Lavdas, Eleftherios; Mavroidis, Panayiotis; Kostopoulos, Spiros; Glotsos, Dimitrios; Roka, Violeta; Koutsiaris, Aristotle G; Batsikas, Georgios; Sakkas, Georgios K; Tsagkalis, Antonios; Notaras, Ioannis; Stathakis, Sotirios; Papanikolaou, Nikos; Vassiou, Katerina

    2013-07-01

    The purpose of this study is to evaluate the ability of T2 turbo spin echo (TSE) axial and sagittal BLADE sequences in reducing or even eliminating motion, pulsatile flow and cross-talk artifacts in lumbar spine MRI examinations. Forty four patients, who had routinely undergone a lumbar spine examination, participated in the study. The following pairs of sequences with and without BLADE were compared: a) T2 TSE Sagittal (SAG) in thirty two cases, and b) T2 TSE Axial (AX) also in thirty two cases. Both quantitative and qualitative analyses were performed based on measurements in different normal anatomical structures and examination of seven characteristics, respectively. The qualitative analysis was performed by experienced radiologists. Also, the presence of image motion, pulsatile flow and cross-talk artifacts was evaluated. Based on the results of the qualitative analysis for the different sequences and anatomical structures, the BLADE sequences were found to be significantly superior to the conventional ones in all the cases. The BLADE sequences eliminated the motion artifacts in all the cases. In our results, it was found that in the examined sequences (sagittal and axial) the differences between the BLADE and conventional sequences regarding the elimination of motion, pulsatile flow and cross-talk artifacts were statistically significant. In all the comparisons, the T2 TSE BLADE sequences were significantly superior to the corresponding conventional sequences regarding the classification of their image quality. In conclusion, this technique appears to be capable of potentially eliminating motion, pulsatile flow and cross-talk artifacts in lumbar spine MR images and producing high quality images in collaborative and non-collaborative patients.

  11. Cross flow ultrafiltration of Cr (VI) using MCM-41, MCM-48 and Faujasite (FAU) zeolite-ceramic composite membranes.

    PubMed

    Basumatary, Ashim Kumar; Kumar, R Vinoth; Ghoshal, Aloke Kumar; Pugazhenthi, G

    2016-06-01

    This work describes the removal of Cr (VI) from aqueous solution in cross flow mode using MCM-41, MCM-48 and FAU zeolite membranes prepared on circular shaped porous ceramic support. Ceramic support was manufactured using locally available clay materials via a facile uni-axial compaction method followed by sintering process. A hydrothermal technique was employed for the deposition of zeolites on the ceramic support. The porosity of ceramic support (47%) is reduced by the formation of MCM-41 (23%), MCM-48 (22%) and FAU (33%) zeolite layers. The pore size of the MCM-41, MCM-48 and FAU membrane is found to be 0.173, 0.142, and 0.153 μm, respectively, which is lower than that of the support (1.0 μm). Cross flow ultrafiltration experiments of Cr (VI) were conducted at five different applied pressures (69-345 kPa) and three cross flow rates (1.11 × 10(-7) - 2.22 × 10(-7) m(3)/s). The filtration studies inferred that the performance of the fabricated zeolite composite membranes is optimum at the maximum applied pressure (345 kPa) and the highest rejection is obtained with the lowest cross flow rate (1.11 × 10(-7) m(3)/s) for all three zeolite membrane. The permeate flux of MCM-41, MCM-48 and FAU zeolite composite membranes are almost remained constant in the entire duration of the separation process. The highest removal of 82% is shown by FAU membrane, while MCM-41 and MCM-48 display 75% and 77% of Cr (VI) removal, respectively for the initial feed concentration of 1000 ppm with natural pH of the solution at an applied pressure of 345 kPa. PMID:27031807

  12. Bubble Formation on a Wall in Cross-Flowing Liquid and Surrounding Fluid Motion,With and Without Heating

    NASA Technical Reports Server (NTRS)

    Bhunia, Avijit; Kamotani, Yasuhiro; Nahra, Henry K.

    2000-01-01

    Application of gas-liquid two-phase flow systems for space-based thermal management and for the HEDS program demands a precise control of bubble size distribution in liquid. The necessity of bulk liquid motion for controlling bubble size and frequency in the space environment has been suggested by recent studies on pool, forced convection boiling and bubble formation in flowing liquid. The present work, consisting of two parts, explores bubble generation at wall in a cross-flowing liquid, i.e., in a forced convection boiling configuration. A schematic is shown. The first part looks into the bubble formation process under isothermal conditions in a reduced gravity environment, by injecting gas through a hole in the wall of a flowing liquid channel. In the latter part with channel wall heating, flow and temperature fields near a single bubble are studied under normal (1-g) and micro-gravity (mu-g) conditions. The objective of the isothermal experiments is to experimentally investigate the effects of liquid cross-flow velocity, gas flow rate, and orifice diameter on bubble formation. Data were taken mainly under reduced gravity conditions but some data were taken in normal gravity for comparison. The reduced gravity experiment was conducted aboard the NASA DC-9 Reduced Gravity Aircraft. The results show that the process of bubble formation and detachment depends on gravity, the orifice diameter (D(sub N)), the gas flow rate (Q(sub g)), and the liquid cross-flow velocity (U(sub L)). The reduced gravity data are shown. The data are analyzed based on a force balance, and two different detachment mechanisms are identified. When the gas momentum is large, the bubble detaches from the injection orifice as the gas momentum overcomes the attaching effects of liquid drag and inertia. The surface tension force is much reduced because a large part of the bubble pinning edge at the orifice is lost as the bubble axis is tilted by the liquid flow. When the gas momentum is small

  13. Analysis and Experimental Verification of New Power Flow Control for Grid-Connected Inverter with LCL Filter in Microgrid

    PubMed Central

    Gu, Herong; Guan, Yajuan; Wang, Huaibao; Wei, Baoze; Guo, Xiaoqiang

    2014-01-01

    Microgrid is an effective way to integrate the distributed energy resources into the utility networks. One of the most important issues is the power flow control of grid-connected voltage-source inverter in microgrid. In this paper, the small-signal model of the power flow control for the grid-connected inverter is established, from which it can be observed that the conventional power flow control may suffer from the poor damping and slow transient response. While the new power flow control can mitigate these problems without affecting the steady-state power flow regulation. Results of continuous-domain simulations in MATLAB and digital control experiments based on a 32-bit fixed-point TMS320F2812 DSP are in good agreement, which verify the small signal model analysis and effectiveness of the proposed method. PMID:24672304

  14. Analysis and experimental verification of new power flow control for grid-connected inverter with LCL filter in microgrid.

    PubMed

    Gu, Herong; Guan, Yajuan; Wang, Huaibao; Wei, Baoze; Guo, Xiaoqiang

    2014-01-01

    Microgrid is an effective way to integrate the distributed energy resources into the utility networks. One of the most important issues is the power flow control of grid-connected voltage-source inverter in microgrid. In this paper, the small-signal model of the power flow control for the grid-connected inverter is established, from which it can be observed that the conventional power flow control may suffer from the poor damping and slow transient response. While the new power flow control can mitigate these problems without affecting the steady-state power flow regulation. Results of continuous-domain simulations in MATLAB and digital control experiments based on a 32-bit fixed-point TMS320F2812 DSP are in good agreement, which verify the small signal model analysis and effectiveness of the proposed method. PMID:24672304

  15. Remotely serviced filter and housing

    DOEpatents

    Ross, M.J.; Zaladonis, L.A.

    1987-07-22

    A filter system for a hot cell comprises a housing adapted for input of air or other gas to be filtered, flow of the air through a filter element, and exit of filtered air. The housing is tapered at the top to make it easy to insert a filter cartridge holds the filter element while the air or other gas is passed through the filter element. Captive bolts in trunnion nuts are readily operated by electromechanical manipulators operating power wrenches to secure and release the filter cartridge. The filter cartridge is adapted to make it easy to change a filter element by using a master-slave manipulator at a shielded window station. 6 figs.

  16. Interpretive geologic cross sections for the Death Valley regional flow system and surrounding areas, Nevada and California

    USGS Publications Warehouse

    Sweetkind, D.S.; Dickerson, R.P.; Blakely, R.J.; Denning, P.D.

    2001-01-01

    This report presents a network of 28 geologic cross sections that portray subsurface geologic relations within the Death Valley regional ground-water system, a ground-water basin that encompasses a 3? x 3? area (approximately 70,000 km2) in southern Nevada and eastern California. The cross sections transect that part of the southern Great Basin that includes Death Valley, the Nevada Test Site, and the potential high-level nuclear waste underground repository at Yucca Mountain. The specific geometric relationships portrayed on the cross sections are discussed in the context of four general sub-regions that have stratigraphic similarities and general consistency of structural style: (1) the Nevada Test Site vicinity; (2) the Spring Mountains, Pahrump Valley and Amargosa Desert region; (3) the Death Valley region; and (4) the area east of the Nevada Test Site. The subsurface geologic interpretations portrayed on the cross sections are based on an integration of existing geologic maps, measured stratigraphic sections, published cross sections, well data, and geophysical data and interpretations. The estimated top of pre-Cenozoic rocks in the cross sections is based on inversion of gravity data, but the deeper parts of the sections are based on geologic conceptual models and are more speculative. The region transected by the cross sections includes part of the southern Basin and Range Province, the northwest-trending Walker Lane belt, the Death Valley region, and the northern Mojave Desert. The region is structurally complex, where a locally thick Tertiary volcanic and sedimentary section unconformably overlies previously deformed Proterozoic through Paleozoic rocks. All of these rocks have been deformed by complex Neogene ex-tensional normal and strike-slip faults. These cross sections form a three-dimensional network that portrays the interpreted stratigraphic and structural relations in the region; the sections form part of the geologic framework that will be

  17. Filter-based measurements of UV-vis mass absorption cross sections of organic carbon aerosol from residential biomass combustion: Preliminary findings and sources of uncertainty

    NASA Astrophysics Data System (ADS)

    Pandey, Apoorva; Pervez, Shamsh; Chakrabarty, Rajan K.

    2016-10-01

    Combustion of solid biomass fuels is a major source of household energy in developing nations. Black (BC) and organic carbon (OC) aerosols are the major PM2.5 (particulate matter with aerodynamic diameter smaller than 2.5 μm) pollutants co-emitted during burning of these fuels. While the optical nature of BC is well characterized, very little is known about the properties of light-absorbing OC (LAOC). Here, we report our preliminary findings on the mass-based optical properties of LAOC emitted from the combustion of four commonly used solid biomass fuels - fuel-wood, agricultural residue, dung-cake, and mixed - in traditional Indian cookstoves. As part of a pilot field study conducted in central India, PM2.5 samples were collected on Teflon filters and analyzed for their absorbance spectra in the 300-900 nm wavelengths at 1 nm resolution using a UV-Visible spectrophotometer equipped with an integrating sphere. The mean mass absorption cross-sections (MAC) of the emitted PM2.5 and OC, at 550 nm, were 0.8 and 0.2 m2 g-1, respectively, each with a factor of ~2.3 uncertainty. The mean absorption Ångström exponent (AǺE) values for PM2.5 were 3±1 between 350 and 550 nm, and 1.2±0.1 between 550 and 880 nm. In the 350-550 nm range, OC had an AǺE of 6.3±1.8. The emitted OC mass, which was on average 25 times of the BC mass, contributed over 50% of the aerosol absorbance at wavelengths smaller than 450 nm. The overall OC contribution to visible solar light (300-900 nm) absorption by the emitted particles was 26-45%. Our results highlight the need to comprehensively and accurately address: (i) the climatic impacts of light absorption by OC from cookstove emissions, and (ii) the uncertainties and biases associated with variability in biomass fuel types and combustion conditions, and filter-based measurement artifacts during determination of MAC values.

  18. Magnetic self-assembly of microparticle clusters in an aqueous two-phase microfluidic cross-flow

    NASA Astrophysics Data System (ADS)

    Abbasi, Niki; Jones, Steven G.; Moon, Byeong-Ui; Tsai, Scott S. H.

    2015-11-01

    We present a technique that self-assembles paramagnetic microparticles on the interface of aqueous two-phase system (ATPS) fluids in a microfluidic cross-flow. A co-flow of the ATPS is formed in the microfluidic cross channel as the flows of a dilute dextran (DEX) phase, along with a flow-focused particle suspension, converges with a dilute polyethylene glycol (PEG) phase. The microparticles arrive at the liquid-liquid interface and self-assemble into particle clusters due to forces on the particles from an applied external magnetic field gradient, and the interfacial tension of the ATPS. The microparticles form clusters at the interface, and once the cluster size grows to a critical value, the cluster passes through the interface. We control the size of the self-assembled clusters, as they pass through the interface, by varying the strength of the applied magnetic field gradient and the ATPS interfacial tension. We observe rich assembly dynamics, from the formation of Pickering emulsions to clusters that are completely encapsulated inside DEX phase droplets. We anticipate that this microparticle self-assembly method may have important biotechnological applications that require the controlled assembly of cells into clusters.

  19. Global 2D stability analysis of the cross lid-driven cavity flow with a streamfunction-vorticity approach

    NASA Astrophysics Data System (ADS)

    Gogoi, Bidyut B.

    2016-07-01

    We have recently analyzed the global two-dimensional (2D) stability of the staggered lid-driven cavity (LDC) flow with a higher order compact (HOC) approach. In the analysis, critical parameters are determined for both the parallel and anti-parallel motion of the lids and a detailed analysis has been carried out on either side of the critical values. In this article, we carry out an investigation of flow stabilities inside a two-sided cross lid-driven cavity with a pair of opposite lids moving in both parallel and anti-parallel directions. On discretization, the governing 2D Navier-Stokes (N-S) equations describing the steady flow and flow perturbations results in a generalized eigenvalue problem which is solved for determining the critical parameters on four different grids. Elaborate computation is performed for a wide range of Reynolds numbers (Re) on either side of the critical values in the range 200 ⩽ Re ⩽ 10000. For flows below the critical Reynolds number Rec, our numerical results are compared with established steady-state results and excellent agreement is obtained in all the cases. For Reynolds numbers above Rec, phase plane and spectral density analysis confirmed the existence of periodic, quasi-periodic, and stable flow patterns.

  20. The filter pads and filtration mechanisms of the devil rays: Variation at macro and microscopic scales.

    PubMed

    Paig-Tran, E W Misty; Kleinteich, Thomas; Summers, Adam P

    2013-09-01

    Three lineages of cartilaginous fishes have independently evolved filter feeding (Lamniformes: Megachasma and Cetorhinus, Orectolobiformes: Rhincodon, and Mobulidae: Manta and Mobula); and the structure of the branchial filters is different in each group. The filter in Rhincodon typus has been described; species within the Lamniformes have simple filamentous filters, but the anatomy and ultrastructure of the branchial filter in the mobulid rays varies and is of functional interest. In most fishes, branchial gill rakers are elongated structures located along the anterior ceratobranchial and/or epibranchial arches; however, mobulid gill rakers are highly modified, flattened, lobe-like structures located on the anterior and posterior epibranchial elements as well as the ceratobranchials. The ultrastructure of the filter lobes can be smooth or covered by a layer of microcilia, and some are denticulated along the dorsal and ventral lobe surface. Flow through the mobulid oropharyngeal cavity differs from other filter-feeding fishes in that water must rapidly deviate from the free stream direction. There is an abrupt 90° turn from the initial inflowing path to move through the laterally directed branchial filter pores, over the gill tissue, and out the ventrally located gill slits. The deviation in the flow must result in tangential shearing stress across the filter surface. This implies that mobulids can use cross-flow filtration in which this shearing force serves as a mechanism to resuspend food particles initially caught by sieving or another capture mode. These particles will be transported by the cross filter flow toward the esophagus. We propose that species with cilia on the rakers augment the shear mediated movement of particles along the filter with ciliary transport.

  1. Cross-shift peak expiratory flow changes are unassociated with respirable coal dust exposure among South African coal miners

    SciTech Connect

    Naidoo, R.N.; Robins, T.G.; Becklake, M.; Seixas, N.; Thompson, M.L.

    2007-12-15

    he objectives of this study were to determine whether cross-shift changes in peak expiratory flow rate (PEFR) were related to respirable dust exposure in South African coalminers. Fifty workers were randomly selected from a cohort of 684 miners from 3 bituminous coal mines in Mpumalanga, South Africa. Peak expiratory efforts were measured prior to the commencement of the shift, and at the end of the shift on at least two occasions separated by at least 2 weeks, with full shift personal dust sampling being conducted on each occasion for each participant. Interviews were conducted, work histories were obtained and cumulative exposure estimates were constructed. Regression models examined the associations of cross-shift changes in PEFR with current and cumulative exposure, controlling for shift, smoking and past history of tuberculosis. There were marginal differences in cross-shift PEFR (ranging from 0.1 to 2 L/min). Linear regression analyses showed no association between cross-shift change in PEFR and current or cumulative exposure. The specific shift worked by participants in the study showed no effect. Our study showed no association between current respirable dust exposure and cross-shift changes in PEFR. There was a non-significant protective effect of cumulative dust exposure on the outcome, suggesting the presence of a 'healthy worker survivor effect' in this data.

  2. Dispositional Differences of Collegiate Athletes' Flow State: A Cross-Cultural Comparison.

    PubMed

    Liu, Weina; Ji, Liu; Watson, Jack C

    2015-01-01

    Csikszentmihalyi (1990) suggested that certain types of people might be better psychologically equipped to experience flow. The purpose of this study was to determine if differences exist in one's ability to experience flow based upon factors such as cultural background, gender, years of specialized training, skill level, and sport event type. The English and Chinese versions of the Dispositional Flow Scale-2 were used to assess trait flow in American (N = 160) and Chinese collegiate athletes (N = 341). Using a one-way ANOVA analysis, the flow scores of American participants were found to be higher than those of Chinese participants, η2 = 0.175, 95% CI: 3.536-3.622, p < .005. The flow scores of male athletes were higher than those of female athletes within the Chinese sample, η2 = 0.032, 95% CI: 3.390-3.486, p < .005. The flow scores of university athletes were higher than those of national team level athletes within the Chinese sample, η2 = 0.044, 95% CI: 3.279-3.501, p < .005. Flow scores for athletes in skill-showing events were higher than those of athletes participating in physical ability-showing events for the American participants, η2 = 0.074, 95% CI: 3.812-3.948, p < .005. This study suggests that individual differences exist in the psychological characteristics of athletes' trait flow. PMID:26055496

  3. Characterization of filtration and regeneration behavior of rigid ceramic filters and particle properties at high temperatures

    SciTech Connect

    Pilz, T.

    1995-12-31

    For power generation with combined cycles or production of so called advanced materials by vapor phase synthesis particle separation at high temperatures is of crucial importance. There, systems working with rigid ceramic barrier filters are either of thermodynamical benefit to the process or essential for producing materials with certain properties. A hot gas filter test rig has been installed to investigate the influence of different parameters e.g. temperature, dust properties, filter media and filtration and regeneration conditions into particle separation at high temperatures. These tests were conducted both with commonly used filter candles and with filter discs made out of the same material. The filter disc is mounted at one side of the test rig. That is why both filters face the same raw gas conditions. The filter disc is flown through by a cross flow arrangement. This bases upon the conviction that for comparison of filtration characteristics of candles with filter discs or other model filters the structure of the dust cakes have to be equal. This way of conducting investigations into the influence of the above mentioned parameters on dust separation at high temperatures follows the new standard VDI 3926. There, test procedures for the characterization of filter media at ambient conditions are prescribed. The paper mainly focuses then on the influence of particle properties (e.g. stickiness etc.) upon the filtration and regeneration behavior of fly ashes with rigid ceramic filters.

  4. The Effect of Fin Pitch on Fluid Elastic Instability of Tube Arrays Subjected to Cross Flow of Water

    NASA Astrophysics Data System (ADS)

    Desai, Sandeep Rangrao; Pavitran, Sampat

    2016-07-01

    Failure of tubes in shell and tube exchangers is attributed to flow induced vibrations of such tubes. There are different excitations mechanisms due to which flow induced vibration occurs and among such mechanisms, fluid elastic instability is the most prominent one as it causes the most violent vibrations and may lead to rapid tube failures within short time. Fluid elastic instability is the fluid-structure interaction phenomenon which occurs when energy input by the fluid force exceeds energy expended in damping. This point is referred as instability threshold and corresponding velocity is referred as critical velocity. Once flow velocity exceeds critical flow velocity, the vibration amplitude increases very rapidly with flow velocity. An experimental program is carried out to determine the critical velocity at instability for plain and finned tube arrays subjected to cross flow of water. The tube array geometry is parallel triangular with cantilever end condition and pitch ratios considered are 2.6 and 2.1. The objective of research is to determine the effect of increase in pitch ratio on instability threshold for plain tube arrays and to assess the effect of addition of fins as well as increase in fin density on instability threshold for finned tube arrays. Plain tube array with two different pitch ratios; 2.1 and 2.6 and finned tube arrays with same pitch ratio; 2.6 but with two different fin pitches; such as fine (10 fpi) and coarse (4 fpi) are considered for the experimentation. Connors' equation that relates critical velocity at instability to different parameters, on which instability depends, has been used as the basis for analysis and the concept of effective diameter is used for the present investigation. The modal parameters are first suitably modified using natural frequency reduction setup that is already designed and developed to reduce natural frequency and hence to achieve experimental simulation of fluid elastic instability within the limited

  5. DEVELOPMENT OF AN ADHESIVE CANDLE FILTER SAFEGUARD DEVICE

    SciTech Connect

    John P. Hurley; Ann K. Henderson; Jan W. Nowok; Michael L. Swanson

    2002-01-01

    In order to reach the highest possible efficiencies in a coal-fired turbine-based power system, the turbine should be directly fired with the products of coal conversion. Two main types of systems employ these turbines: those based on pressurized fluidized-bed combustors and those based on integrated gasification combined cycles. In both systems, suspended particulates must be cleaned from the gas stream before it enters the turbine so as to prevent fouling and erosion of the turbine blades. To produce the cleanest gas, barrier filters are being developed and are in use in several facilities. Barrier filters are composed of porous, high-temperature materials that allow the hot gas to pass but collect the particulates on the surface. The three main configurations of the barrier filters are candle, cross-flow, and tube filters. Both candle and tube filters have been tested extensively. They are composed of coarsely porous ceramic that serves as a structural support, overlain with a thin, microporous ceramic layer on the dirty gas side that serves as the primary filter surface. They are highly efficient at removing particulate matter from the gas stream and, because of their ceramic construction, are resistant to gas and ash corrosion. However, ceramics are brittle and individual elements can fail, allowing particulates to pass through the hole left by the filter element and erode the turbine. Preventing all failure of individual ceramic filter elements is not possible at the present state of development of the technology. Therefore, safeguard devices (SGDs) must be employed to prevent the particulates streaming through occasional broken filters from reaching the turbine. However, the SGD must allow for the free passage of gas when it is not activated. Upon breaking of a filter, the SGD must either mechanically close or quickly plug with filter dust to prevent additional dust from reaching the turbine. Production of a dependable rapidly closing autonomous mechanical

  6. Data Assimilation in a Solar Dynamo Model Using Ensemble Kalman Filters: Sensitivity and Robustness in Reconstruction of Meridional Flow Speed

    NASA Astrophysics Data System (ADS)

    Dikpati, Mausumi; Anderson, Jeffrey L.; Mitra, Dhrubaditya

    2016-09-01

    We implement an Ensemble Kalman Filter procedure using the Data Assimilation Research Testbed for assimilating “synthetic” meridional flow-speed data in a Babcock–Leighton-type flux-transport solar dynamo model. By performing several “observing system simulation experiments,” we reconstruct time variation in meridional flow speed and analyze sensitivity and robustness of reconstruction. Using 192 ensemble members including 10 observations, each with 4% error, we find that flow speed is reconstructed best if observations of near-surface poloidal fields from low latitudes and tachocline toroidal fields from midlatitudes are assimilated. If observations include a mixture of poloidal and toroidal fields from different latitude locations, reconstruction is reasonably good for ≤slant 40 % error in low-latitude data, even if observational error in polar region data becomes 200%, but deteriorates when observational error increases in low- and midlatitude data. Solar polar region observations are known to contain larger errors than those in low latitudes; our forward operator (a flux-transport dynamo model here) can sustain larger errors in polar region data, but is more sensitive to errors in low-latitude data. An optimal reconstruction is obtained if an assimilation interval of 15 days is used; 10- and 20-day assimilation intervals also give reasonably good results. Assimilation intervals \\lt 5 days do not produce faithful reconstructions of flow speed, because the system requires a minimum time to develop dynamics to respond to flow variations. Reconstruction also deteriorates if an assimilation interval \\gt 45 days is used, because the system’s inherent memory interferes with its short-term dynamics during a substantially long run without updating.

  7. ADVANCED HOT GAS FILTER DEVELOPMENT

    SciTech Connect

    E.S. Connolly; G.D. Forsythe

    1998-12-22

    Advanced, coal-based power plants will require durable and reliable hot gas filtration systems to remove particulate contaminants from the gas streams to protect downstream components such as turbine blades from erosion damage. It is expected that the filter elements in these systems will have to be made of ceramic materials to withstand goal service temperatures of 1600 F or higher. Recent demonstration projects and pilot plant tests have indicated that the current generation of ceramic hot gas filters (cross-flow and candle configurations) are failing prematurely. Two of the most promising materials that have been extensively evaluated are clay-bonded silicon carbide and alumina-mullite porous monoliths. These candidates, however, have been found to suffer progressive thermal shock fatigue damage, as a result of rapid cooling/heating cycles. Such temperature changes occur when the hot filters are back-pulsed with cooler gas to clean them, or in process upset conditions, where even larger gas temperature changes may occur quickly and unpredictably. In addition, the clay-bonded silicon carbide materials are susceptible to chemical attack of the glassy binder phase that holds the SiC particles together, resulting in softening, strength loss, creep, and eventual failure.

  8. Cross-hole tracer experiment reveals rapid fluid flow and low effective porosity in the upper oceanic crust

    NASA Astrophysics Data System (ADS)

    Neira, N. M.; Clark, J. F.; Fisher, A. T.; Wheat, C. G.; Haymon, R. M.; Becker, K.

    2016-09-01

    Numerous field, laboratory, and modeling studies have explored the flows of fluid, heat, and solutes during seafloor hydrothermal circulation, but it has been challenging to determine transport rates and flow directions within natural systems. Here we present results from the first cross-hole tracer experiment in the upper oceanic crust, using four subseafloor borehole observatories equipped with autonomous samplers to track the transport of a dissolved tracer (sulfur hexafluoride, SF6) injected into a ridge-flank hydrothermal system. During the first three years after tracer injection, SF6 was transported both north and south through the basaltic aquifer. The observed tracer transport rate of ∼2-3 m/day is orders of magnitude greater than bulk rates of flow inferred from thermal and chemical observations and calculated with coupled fluid-heat flow simulations. Taken together, these results suggest that the effective porosity of the upper volcanic crust through which much tracer was transported is <1%, with fluid flowing rapidly along a few well-connected channels. This is consistent with the heterogeneous (layered, faulted, and/or fractured) nature of the volcanic upper oceanic crust.

  9. Falkner-Skan flow of a magnetic-Carreau fluid past a wedge in the presence of cross diffusion effects

    NASA Astrophysics Data System (ADS)

    Raju, C. S. K.; Sandeep, N.

    2016-08-01

    Heat and mass transfer in the Falkner-Skan flow of a Carreau fluid past a wedge is investigated numerically. In most of the existing studies thermal radiation is linear. Due to the prominent importance of the various industrial applications, in this study we considered the nonlinear thermal radiation along with cross diffusion effects for the heat and mass transfer controlling process. Numerical results are presented graphically as well as in tabular form by enforcing Runge-Kutta and Newton's methods. We also validated the present results by comparing with the published results and found favourable agreement. We presented solutions for the flow separation, decelerating and accelerating cases. We observed that the thermal and concentration boundary layers are non-uniform for the flow separation, decelerating and accelerating cases. For industrial needs, we analysed the heat and mass transfer rates of the accelerating, decelerating and flow separation cases and found that the heat transfer rate is high in the accelerating case when compared with the decelerating case. From this we can conclude that the decelerating flow over a wedge is very useful for cooling applications.

  10. Prediction of Bubble Diameter at Detachment from a Wall Orifice in Liquid Cross Flow Under Reduced and Normal Gravity Conditions

    NASA Technical Reports Server (NTRS)

    Nahra, Henry K.; Kamotani, Y.

    2003-01-01

    Bubble formation and detachment is an integral part of the two-phase flow science. The objective of the present work is to theoretically investigate the effects of liquid cross-flow velocity, gas flow rate embodied in the momentum flux force, and orifice diameter on bubble formation in a wall-bubble injection configuration. A two-dimensional one-stage theoretical model based on a global force balance on the bubble evolving from a wall orifice in a cross liquid flow is presented in this work. In this model, relevant forces acting on the evolving bubble are expressed in terms of the bubble center of mass coordinates and solved simultaneously. Relevant forces in low gravity included the momentum flux, shear-lift, surface tension, drag and inertia forces. Under normal gravity conditions, the buoyancy force, which is dominant under such conditions, can be added to the force balance. Two detachment criteria were applicable depending on the gas to liquid momentum force ratio. For low ratios, the time when the bubble acceleration in the direction of the detachment angle is greater or equal to zero is calculated from the bubble x and y coordinates. This time is taken as the time at which all the detaching forces that are acting on the bubble are greater or equal to the attaching forces. For high gas to liquid momentum force ratios, the time at which the y coordinate less the bubble radius equals zero is calculated. The bubble diameter is evaluated at this time as the diameter at detachment from the fact that the bubble volume is simply given by the product of the gas flow rate and time elapsed. Comparison of the model s predictions was also made with predictions from a two-dimensional normal gravity model based on Kumar-Kuloor formulation and such a comparison is presented in this work.

  11. Analysis of Extensive Cross-Flow Separation using Higher-Order RANS Closure Models

    NASA Technical Reports Server (NTRS)

    Morison, J. H.; Panaras, A. G.; Gatski, T. B.; Georgantopoulos, G. A.

    2003-01-01

    The turbulent flow fields associated with the incompressible flow over a 6:1 prolate spheroid at high angle of attack, and the supersonic flow over an ogive cylinder are studied. Both these flows are characterized by large separation and vortical flow regions and therefore provide a challenging database for comparison of turbulent closure models. Of interest is the ability to predict the effects of separation and associated vortical motion common to both flows. Two turbulent models are investigated that each represent the class of linear eddy-viscosity models (LEVMs) and explicit algebraic stress models (EASMs). Since the EASM accounts for anisotropic effects, the in- fluence of these effects on flow field predictions can be assessed. The EASM model is shown to both improve the separation location prediction and pressure trough under the secondary vortex on the 6:1 prolate spheroid at high angle of attack and high Reynolds number, and improve the prediction of the separation location on a supersonic ogive cylinder.

  12. Analytic expressions for Atomic Layer Deposition: coverage, throughput, and materials utilization in cross-flow, particle coating, and spatial ALD

    SciTech Connect

    Yanguas-Gil, Angel; Elam, Jeffrey W.

    2014-05-01

    In this work, the authors present analytic models for atomic layer deposition (ALD) in three common experimental configurations: cross-flow, particle coating, and spatial ALD. These models, based on the plug-flow and well-mixed approximations, allow us to determine the minimum dose times and materials utilization for all three configurations. A comparison between the three models shows that throughput and precursor utilization can each be expressed by universal equations, in which the particularity of the experimental system is contained in a single parameter related to the residence time of the precursor in the reactor. For the case of cross-flow reactors, the authors show how simple analytic expressions for the reactor saturation profiles agree well with experimental results. Consequently, the analytic model can be used to extract information about the ALD surface chemistry (e. g., the reaction probability) by comparing the analytic and experimental saturation profiles, providing a useful tool for characterizing new and existing ALD processes. (C) 2014 American Vacuum Society

  13. Cross sectoral and scale-up impacts of greywater recycling technologies on catchment hydrological flows.

    PubMed

    Bertrand, N; Jefferson, B; Jeffrey, P

    2008-01-01

    With the growth of urban areas and climate change, decisions need to be taken to improve water management. This paper reports an assessment of the impact of greywater recycling systems on catchment scale hydrological flows. A simulation model developed in InfoWorks CS (Wallingford Software Ltd) was used to evaluate how river flows, sewer flows, surface runoff and flooding events may be influenced when grey water recycling systems of different number and scale are implemented in a representative catchment. The simulations show the effectiveness of greywater recycling systems in reducing total wastewater volume and flood volume. However, no hydraulic impacts due to implementation of greywater was identified by the model.

  14. Evaluation of Radial Flow Fluidized Filter (R3F) Followed by Microfiltration and Ultrafiltration Systems in Calimesa, California

    EPA Science Inventory

    U.S. EPA coordinated a field study with South Mesa Water Utility to look for treatment alternatives for California State Project Water in the small community of Calimesa, California. EPA evaluated the performance of a system comprised of Radial Flow Fluidized Filtration (R3f) fo...

  15. Turbulent cascade at 1 AU in high cross-helicity flows.

    PubMed

    Smith, Charles W; Stawarz, Joshua E; Vasquez, Bernard J; Forman, Miriam A; MacBride, Benjamin T

    2009-11-13

    Analysis of the scaling of the mixed third moments of velocity and magnetic fluctuations in the solar wind plasma, and the energy cascade rates derived from the scaling, reveal a strong dependence on the amount of cross-field correlation between the velocity and magnetic field fluctuations. When the correlation is greater than about 75%, the cascade rate of the outward-propagating (majority) component, and of the total energy and the cross-helicity are surprisingly negative. This indicates a back transfer of energy from small to large scales within the inertial range of the dominant outward-propagating component. It is clear that the transfer of energy acts to reinforce the dominance of the outward-propagating (majority) component and may explain, in part, the persistent observations of large cross-field correlations that have been a defining aspect of solar wind physics for almost 40 years. PMID:20365972

  16. In-medium NN cross sections determined from the nuclear stopping and collective flow in heavy-ion collisions at intermediate energies

    SciTech Connect

    Zhang Yingxun; Li Zhuxia; Danielewicz, Pawel

    2007-03-15

    In-medium nucleon-nucleon scattering cross sections are explored by comparing results of quantum molecular dynamics simulations to data on stopping and on elliptic and directed flow in intermediate-energy heavy-ion collisions. The comparison points to in-medium cross sections which are suppressed at low energies but not at higher energies. Positive correlations are found between the degree of stopping and the magnitudes of elliptic and directed flows.

  17. Mechanistic modeling of evaporating thin liquid film instability on a BWR fuel rod with parallel and cross vapor flow

    NASA Astrophysics Data System (ADS)

    Hu, Chih-Chieh

    This work has been aimed at developing a mechanistic, transient, 3-D numerical model to predict the behavior of an evaporating thin liquid film on a non-uniformly heated cylindrical rod with simultaneous parallel and cross flow of vapor. Interest in this problem has been motivated by the fact that the liquid film on a full-length boiling water reactor fuel rod may experience significant axial and azimuthal heat flux gradients and cross flow due to variations in the thermal-hydraulic conditions in surrounding subchannels caused by proximity to inserted control blade tip and/or the top of part-length fuel rods. Such heat flux gradients coupled with localized cross flow may cause the liquid film on the fuel rod surface to rupture, thereby forming a dry hot spot. These localized dryout phenomena can not be accurately predicted by traditional subchannel analysis methods in conjunction with empirical dryout correlations. To this end, a numerical model based on the Level Contour Reconstruction Method was developed. The Standard k-ε turbulence model is included. A cylindrical coordinate system has been used to enhance the resolution of the Level Contour Reconstruction Model. Satisfactory agreement has been achieved between the model predictions and experimental data. A model of this type is necessary to supplement current state-of-the-art BWR core thermal-hydraulic design methods based on subchannel analysis techniques coupled with empirical dry out correlations. In essence, such a model would provide the core designer with a "magnifying glass" by which the behavior of the liquid film at specific locations within the core (specific axial node on specific location within a specific bundle in the subchannel analysis model) can be closely examined. A tool of this type would allow the designer to examine the effectiveness of possible design changes and/or modified control strategies to prevent conditions leading to localized film instability and possible fuel failure.

  18. Correlation formulas for the frost thickness and heat transfer coefficient on a cylinder in humid air cross flow

    SciTech Connect

    Sengupta, S.; Sherif, S.A.; Wong, K.V.

    1995-12-31

    This paper reports on results of an experimental investigation where the emphasis was placed on obtaining empirical correlations for the frost thickness-time history and the heat transfer coefficient-time history for a cylinder in humid air cross flow. The facility employed for the investigation consisted of a low velocity wind tunnel comprised of a rectangular test section, a transition section and a honeycomb placed at the tunnel entrance. An external refrigerator was used to cool an antifreeze solution having a mixture of 90% methanol and 10% ethylene glycol. Measured parameters included, among other things, the heat transfer coefficient as well as the frost thickness.

  19. Water Filters

    NASA Technical Reports Server (NTRS)

    1993-01-01

    The Aquaspace H2OME Guardian Water Filter, available through Western Water International, Inc., reduces lead in water supplies. The filter is mounted on the faucet and the filter cartridge is placed in the "dead space" between sink and wall. This filter is one of several new filtration devices using the Aquaspace compound filter media, which combines company developed and NASA technology. Aquaspace filters are used in industrial, commercial, residential, and recreational environments as well as by developing nations where water is highly contaminated.

  20. Enzyme entrapped nanoporous scaffolds formed through flow induced gelation in microfluidic filter device for sensitive biosensing of organophosphorus compounds

    SciTech Connect

    Lu, Donglai; Shao, Guocheng; Du, Dan; Wang, Jun; Wang, Limin; Wang, Wanjun; Lin, Yuehe

    2011-02-01

    A novel and versatile processing method was developed for the formation of gel scaffolds with in-situ AChE-AuNPs immobilization for biosensing of organophosphorus compounds. The biosensor designed by our new approach shows high sensitivity, selectivity and reactivation efficiency. This flow induced immobilziation technique opens up new pathways for designing simple, fast, biocompatible, and cost-effective process for enhanced sensor performance and on-site testing of a variety of toxic organophosphorus compounds.

  1. Sintered composite filter

    DOEpatents

    Bergman, W.

    1986-05-02

    A particulate filter medium formed of a sintered composite of 0.5 micron diameter quartz fibers and 2 micron diameter stainless steel fibers is described. Preferred composition is about 40 vol.% quartz and about 60 vol.% stainless steel fibers. The media is sintered at about 1100/sup 0/C to bond the stainless steel fibers into a cage network which holds the quartz fibers. High filter efficiency and low flow resistance are provided by the smaller quartz fibers. High strength is provided by the stainless steel fibers. The resulting media has a high efficiency and low pressure drop similar to the standard HEPA media, with tensile strength at least four times greater, and a maximum operating temperature of about 550/sup 0/C. The invention also includes methods to form the composite media and a HEPA filter utilizing the composite media. The filter media can be used to filter particles in both liquids and gases.

  2. Developing flow in S-shaped ducts. 1: Square cross-section duct

    NASA Technical Reports Server (NTRS)

    Taylor, A. M. K. P.; Whitelaw, J. H.; Yianneskis, M.

    1982-01-01

    Laser-Doppler velocimetry was used to measure the laminar and turbulent flow in an S-duct formed with two 22.5 deg sectors of a bend with ratio of mean radius of curvature to hydraulic diameter of 7.0. The boundary layers at the inlet to the bend were about 25% and 15% of the hydraulic diameter for the laminar and turbulent flows, respectively. Pressure-driven secondary flows develop in the first half of the S-duct and persist into the second half but are largely reversed by the exit plane as a consequence of the change in the sense of curvature. There is, however, a region near the outer wall of the second bend where the redistribution of the streamwise isotachs results in a reinforcement of the secondary flow which was established in the first half of the S-duct. The net redistribution of the streamwise isotachs is comparable to that occurring in unidirectional bends of stronger curvature. The wall pressure distribution was also measured for the turbulent flow and quantifies the expected large variations in the longitudinal pressure gradient distributions which occur at different radial locations.

  3. The Transient Regeneration in the Patchy Cleaning of Rigid Gas Filters--Comparison of Modeling to Experiment

    SciTech Connect

    Ferer, M.V.; Dittler, A.; Kasper, G.; Smith, D.H.

    2002-09-19

    The experimental investigations performed within the scope of the present contribution are carried out in a lab scale filter test rig, which is built according to German VDI guideline 3926. The filter coupon (15 cm diameter) under investigation is mounted parallel to the crude gas channel which enables cross flow filtration as experienced in filter housings. Besides the photometric concentration monitor and the control device, an optical measuring system is mounted on the filter test rig opposite the filter coupon. This measuring system enables the full-field in situ measurement of the dust cake height distribution on the surface of the filter medium. From these measurements, we obtain the overall frequency of regeneration as well as the local frequencies of regeneration and the patch size distribution, as discussed later. In addition, we investigate the influence of the regeneration behavior on the filtration performance (time dependence of filtration cycle times and residual pressure drop) of the filter medium.

  4. A high-efficiency cross-flow micronebulizer interface for capillary electrophoresis and inductively coupled plasma mass spectrometry.

    PubMed

    Li, J; Umemura, T; Odake, T; Tsunoda, K

    2001-12-15

    A pneumatic nebulizer interface for capillary electrophoresis (CE) and inductively coupled plasma mass spectrometry (ICPMS) is reported. The interface is constructed using a high-efficiency cross-flow micronebulizer (HECFMN) and has the following features. (1) Makeup solutions can be fed to the interface by nebulizer self-aspiration and liquid gravity pressurization. (2) The liquid dead volume of the interface is approximately 65 nL, much smaller than those (200-2500 nL) reported for other interfaces. (3) The interface can be stably operated at a liquid flow rate down to 5 microL/min with a high analyte transport efficiency up to 95% to the plasma and (4) does not induce noticeable laminar flow in the CE capillary at typical nebulizer gas flow rates of 0.8-1.2 L/min. Because of these features, baseline resolution of 10 lanthanides with a CE-ICPMS system using the HECFMN interface is achieved, and detection limits and peak asymmetry are 0.05-1 microg/L and 0.93-1.23, respectively, improved significantly over those reported previously for a CE-ICPMS system using a high-efficiency nebulizer interface. Peak precision for the 10 lanthanides is in the range of 6.2-12.3% RSD (N = 5). Peak widths are from 9.1 s for 139La to 17.9 s for 175Lu. The effects of nebulizer gas flow rate, makeup solution flow rate, and spray chamber volume on CE-ICPMS signal intensity and separation are also evaluated for the HECFMN interface by the separation of Cr3+ and Cr2O7(2-).

  5. Biological Filters.

    ERIC Educational Resources Information Center

    Klemetson, S. L.

    1978-01-01

    Presents the 1978 literature review of wastewater treatment. The review is concerned with biological filters, and it covers: (1) trickling filters; (2) rotating biological contractors; and (3) miscellaneous reactors. A list of 14 references is also presented. (HM)

  6. The effect of filter cakes on filter medium resistance

    SciTech Connect

    Chase, G.G.; Arconti, J.; Kanel, J.

    1994-10-01

    The high resistance of a filter medium to fluid flow is a universal problem affecting many industries. The small thickness of the filter media makes local pressure and porosity measurements impractical. Analysis of the continuum equations and boundary conditions provide a basis for defining a relative medium resistance. Experiments are conducted on three particulate materials and on three different high flow rate filter media. The results show that the increase in medium resistance varies up to about four times the resistance of a clean filter medium with no cake present. The results also show that in most cases the relative resistance is dependent upon cake height.

  7. Effect of cross-flow on PEFC liquid-water distribution: An in-situ high-resolution neutron radiography study

    NASA Astrophysics Data System (ADS)

    Santamaria, Anthony D.; Becton, Maxwell K.; Cooper, Nathanial J.; Weber, Adam Z.; Park, Jae Wan

    2015-10-01

    Liquid-water management in polymer-electrolyte fuel cells (PEFCs) remains an area of ongoing research. To enhance water removal, certain flow-fields induce cross-flow, or flow through the gas-diffusion layer (GDL) via channel-to-channel pressure differences. While beneficial to water removal, cross-flow comes at the cost of higher pumping pressures and may lead to membrane dehydration and other deleterious issues. This paper examines the impact of cross-flow on component saturation levels as determined through in-plane high-resolution neutron radiography. Various humidities and operating conditions are examined, and the results demonstrate that cell saturation levels correlate strongly with the level of cross-flow rate, and lower GDL saturation levels are found to correlate with an increase in permeability at higher flow rates. Effective water removal is found to occur at channel-to-channel pressure gradients greater than the measured breakthrough pressure of the GDL, evidence that similar liquid-water transport mechanisms exist for under-land area transport as in transverse GDL flow.

  8. The removal of 1,4-dioxane from polyester manufacturing process wastewater using an up-flow Biological Aerated Filter (UBAF) packed with tire chips.

    PubMed

    Han, Thi-Hiep; Han, Ji-Sun; So, Myung-Ho; Seo, Jang-Won; Ahn, Chang-Min; Min, Dong Hee; Yoo, Yeon Sun; Cha, Daniel K; Kim, Chang Gyun

    2012-01-01

    1,4-Dioxane is one of the by-products from the polyester manufacturing process, which has been carelessly discharged into water bodies and is a weak human carcinogen. In this study, a laboratory-scale, up-flow biological aerated filter (UBAF), packed with tire chips, was investigated for the treatment of 1,4-dioxane. The UBAF was fed with effluent, containing an average of 31 mg/L of 1,4-dioxane, discharged from an anaerobic treatment unit at H Co. in the Gumi Industrial Complex, South Korea. In the batch, a maximum of 99.5 % 1,4-dioxane was removed from an influent containing 25.6 mg/L. In the continuous mode, the optimal empty bed contact time (EBCT) and air to liquid flow rate (A:L) were 8.5 hours and 30:1, respectively. It was also found that the removal efficiency of 1,4-dioxane increased with increasing loading rate within the range 0.04 to 0.31 kg 1,4-dioxane/m(3)·day. However, as the COD:1,4-dioxane ratio was increased within the range 3 to 46 (mg/L COD)/(mg/L 1,4-dioxane), the removal efficiency unexpectedly decreased. PMID:22217090

  9. Treatment of a sulfate-rich groundwater contaminated with perchloroethene in a hydroponic plant root mat filter and a horizontal subsurface flow constructed wetland at pilot-scale.

    PubMed

    Chen, Zhongbing; Kuschk, Peter; Paschke, Heidrun; Kästner, Matthias; Müller, Jochen A; Köser, Heinz

    2014-12-01

    A hydroponic plant root mat filter (HPRMF) was compared over 7months with a horizontal subsurface flow constructed wetland (HSSF CW) regarding the removal of perchloroethene (PCE) (about 2 mg L(-1)) from a sulfate- (850 mg L(-1)) and ammonia-rich (50 mg L(-1)) groundwater with a low TOC content. At a mean area specific inflow PCE load of 56 mg m(-2)d(-1), after 4m from inlet, the mean PCE removal during summer time reached 97% in the HPRMF and almost 100% in the HSSF CW. Within the first 2m in the HSSF CW metabolites like dichloroethenes, vinyl chloride and ethene accumulated, their concentrations decreased further along the flow path. Moreover, the tidal operation (a 7-d cycle) in the HSSFCW decreased the accumulation of PCE metabolites within the first 1m of the bed. The carcinogenic degradation metabolite vinyl chloride was not detected in the HPRMF. The smaller accumulation of the degradation metabolites in the HPRMF correlated with its higher redox potential. It can be concluded from this study that HPRMF appears an interesting alternative for special water treatment tasks and that tidal operation will show some positive effects on the removal of the accumulated PCE metabolites in HSSF CW.

  10. An experimental study of sound generated by flows around cylinders of different cross-section

    NASA Astrophysics Data System (ADS)

    King, W. F.; Pfizenmaier, E.

    2009-12-01

    The sound radiated by rigid cylinders placed transversely in a uniform stream has been measured in an anechoic wind tunnel over a range of Mach numbers ( M=0.09-0.2). The cylinders have different cross-sections, e.g., circular, square, rectangular, elliptic, and circular with lateral ribs or knurled surfaces. Different length to diameter ratios of the cylinders are also investigated. Results are presented as narrow band spectra, measured in the far field (acoustic as well as geometric). All spectra are presented with dimensionless (scaled) axes, as well as the original dimensional scales. It is shown that elliptic cross-sections are less noisy, compared to all other cylinders, but noise abatement techniques such as lateral ribs and knurled surfaces can also reduce tonal radiated noise. Two practical applications of these experiments are the reduction of radiated noise from pantographs of high-speed railway trains, and from the landing gear of modern passenger aircraft.

  11. Higher-order compositional modeling of three-phase flow in 3D fractured porous media based on cross-flow equilibrium

    SciTech Connect

    Moortgat, Joachim Firoozabadi, Abbas

    2013-10-01

    Numerical simulation of multiphase compositional flow in fractured porous media, when all the species can transfer between the phases, is a real challenge. Despite the broad applications in hydrocarbon reservoir engineering and hydrology, a compositional numerical simulator for three-phase flow in fractured media has not appeared in the literature, to the best of our knowledge. In this work, we present a three-phase fully compositional simulator for fractured media, based on higher-order finite element methods. To achieve computational efficiency, we invoke the cross-flow equilibrium (CFE) concept between discrete fractures and a small neighborhood in the matrix blocks. We adopt the mixed hybrid finite element (MHFE) method to approximate convective Darcy fluxes and the pressure equation. This approach is the most natural choice for flow in fractured media. The mass balance equations are discretized by the discontinuous Galerkin (DG) method, which is perhaps the most efficient approach to capture physical discontinuities in phase properties at the matrix-fracture interfaces and at phase boundaries. In this work, we account for gravity and Fickian diffusion. The modeling of capillary effects is discussed in a separate paper. We present the mathematical framework, using the implicit-pressure-explicit-composition (IMPEC) scheme, which facilitates rigorous thermodynamic stability analyses and the computation of phase behavior effects to account for transfer of species between the phases. A deceptively simple CFL condition is implemented to improve numerical stability and accuracy. We provide six numerical examples at both small and larger scales and in two and three dimensions, to demonstrate powerful features of the formulation.

  12. A Simple Candle Filter Safeguard Device

    SciTech Connect

    Hurley, J.P.; Henderson, A.K.; Swanson, M.L.

    2002-09-18

    In order to reach the highest possible efficiencies in a coal-fired turbine-based power system, the turbine should be directly fired with the products of coal utilization. Two main designs employ these turbines: those based on pressurized fluidized-bed combustors (PFBCs) and those based on integrated gasification combined cycles (IGCCs). In both designs, the suspended particulates, or dust, must be cleaned from the gas before it enters the turbine to prevent fouling and erosion of the blades. To produce the cleanest gas, barrier filters are being developed and are in commercial use. Barrier filters are composed of porous, high-temperature materials that allow the hot gas to pass but collect the dust on the surface. The three main configurations are candle, cross-flow, and tube. Both candle and tube filters have been tested extensively. They are primarily composed of coarsely porous ceramic that serves as a structural support, overlain with a thin, microporous ceramic layer o n the dirty gas side that serves as the primary filter surface. They are highly efficient at removing particulate matter from the gas stream and, because of their ceramic construction, are resistant to gas and ash corrosion. However, ceramics are brittle, and individual elements can fail, allowing the particulates to pass through the hole left by the filter element and erode the turbine. Because of the possibility of occasional filter breakage, safeguard devices (SGDs) must be employed to prevent the dust streaming through broken filters from reaching the turbine. The Energy & Environmental Research Center (EERC) safeguard device is composed of three main parts: the ceramic substrate, the adhesive coating, and the safeguard device housing. This report describes the development and laboratory testing of each of those parts as well as the bench-scale performance of both types of complete SGDs.

  13. FILTER TREATMENT

    DOEpatents

    Sutton, J.B.; Torrey, J.V.P.

    1958-08-26

    A process is described for reconditioning fused alumina filters which have become clogged by the accretion of bismuth phosphate in the filter pores, The method consists in contacting such filters with faming sulfuric acid, and maintaining such contact for a substantial period of time.

  14. Highly stable pyridinium-functionalized cross-linked anion exchange membranes for all vanadium redox flow batteries

    NASA Astrophysics Data System (ADS)

    Zeng, L.; Zhao, T. S.; Wei, L.; Zeng, Y. K.; Zhang, Z. H.

    2016-11-01

    It has recently been demonstrated that the use of anion exchange membranes (AEMs) in vanadium redox flow batteries (VRFBs) can reduce the migration of vanadium ions through the membrane due to the Donnan exclusion effect among the positively charged functional groups and vanadium ions. However, AEMs are plagued by low chemical stability in harsh chemical environments. Here we propose and fabricate a pyridinium-functionalized cross-linked AEM for VRFBs. The pyridinium-functionalized bromomethylated poly (2,6-dimethyl-1,4-phenylene oxide) exhibits a superior chemical stability as a result of the strengthened internal cross-linking networks and the chemical inertness of the polymer backbone. Therefore, the membrane exhibits littler decay in a harsh environment for 20 days during the course of an ex situ immersion test. A cycling test also demonstrates that the VRFB assembled with the membrane enable to retain 80% of the initial discharge capacity over 537 cycles with a capacity decay rate of 0.037% cycle-1. Meanwhile, the membrane also shows a low vanadium permeability and a reasonably high conductivity in supporting electrolytes. Hence, all the measurements and performance tests reported in this work suggest that the membrane is a promising AEM for redox flow batteries to achieve excellent cycling stability and superior cell performance.

  15. The global monsoon division combining the k-means clustering method and low-level cross-equatorial flow

    NASA Astrophysics Data System (ADS)

    Jiang, Ning; Qian, Weihong; Leung, Jeremy Cheuk-Hin

    2016-10-01

    The global monsoon domain has been recently determined utilizing two criteria: difference of local maximum and minimum pentad-mean precipitation rates exceeding 4 mm day-1, and wind reversal of low-level cross-equatorial flow. In this paper, 22 major dry-wet alteration regions under six categories were first derived through the k-means clustering method from the climatological evolution of global precipitation. Considering the seasonal influences of the low-level cross-equatorial flow in these major dry-wet alternation regions, the global monsoon was objectively divided into 16 major regions under five climatological precipitation categories. Nine monsoon regions are distributed between Asia and Australia while four regions are from Africa to the Southwest Indian Ocean and three regions in Americas. Precipitation trends during rainy seasons of 1981-2010 were examined in the 16 monsoon regions. Four regions with decreasing trends of precipitation are located in Africa and the Southwest Indian Ocean while three regions with increasing trends are situated in Americas. Six regions of increasing precipitation trends are concentrated in Asia and the biggest increasing trend is found in south China.

  16. Method and apparatus for a self-cleaning filter

    DOEpatents

    Diebold, James P.; Lilley, Arthur; Browne, III, Kingsbury; Walt, Robb Ray; Duncan, Dustin; Walker, Michael; Steele, John; Fields, Michael

    2013-09-10

    A method and apparatus for removing fine particulate matter from a fluid stream without interrupting the overall process or flow. The flowing fluid inflates and expands the flexible filter, and particulate is deposited on the filter media while clean fluid is permitted to pass through the filter. This filter is cleaned when the fluid flow is stopped, the filter collapses, and a force is applied to distort the flexible filter media to dislodge the built-up filter cake. The dislodged filter cake falls to a location that allows undisrupted flow of the fluid after flow is restored. The shed particulate is removed to a bin for periodic collection. A plurality of filter cells can operate independently or in concert, in parallel, or in series to permit cleaning the filters without shutting off the overall fluid flow. The self-cleaning filter is low cost, has low power consumption, and exhibits low differential pressures.

  17. Method and apparatus for a self-cleaning filter

    SciTech Connect

    Diebold, James P.; Lilley, Arthur; Browne, III, Kingsbury; Walt, Robb Ray; Duncan, Dustin; Walker, Michael; Steele, John; Fields, Michael

    2010-11-16

    A method and apparatus for removing fine particulate matter from a fluid stream without interrupting the overall process or flow. The flowing fluid inflates and expands the flexible filter, and particulate is deposited on the filter media while clean fluid is permitted to pass through the filter. This filter is cleaned when the fluid flow is stopped, the filter collapses, and a force is applied to distort the flexible filter media to dislodge the built-up filter cake. The dislodged filter cake falls to a location that allows undisrupted flow of the fluid after flow is restored. The shed particulate is removed to a bin for periodic collection. A plurality of filter cells can operate independently or in concert, in parallel, or in series to permit cleaning the filters without shutting off the overall fluid flow. The self-cleaning filter is low cost, has low power consumption, and exhibits low differential pressures.

  18. Operational real-time modeling with ensemble Kalman filter of variably saturated subsurface flow including stream-aquifer interaction and parameter updating

    NASA Astrophysics Data System (ADS)

    Hendricks Franssen, H. J.; Kaiser, H. P.; Kuhlmann, U.; Bauser, G.; Stauffer, F.; Müller, R.; Kinzelbach, W.

    2011-02-01

    Urban groundwater is frequently contaminated, and the exact location of the pollution spots is often unknown. Intelligent monitoring of the temporal variations in groundwater flow in such an area assists in selectively extracting groundwater of drinking water quality. Here an example from the city of Zurich (Switzerland) is shown. The monitoring strategy consists of using the ensemble Kalman filter (EnKF) for optimally combining online observations and online models for the real-time characterization of groundwater flow. We conducted numerical simulation experiments for the period January 2004 to December 2007 with a 3-D finite element model for variably saturated groundwater flow. It was found that the daily assimilation of piezometric head data with EnKF results in a better characterization of piezometric heads than does a model which is inversely calibrated with historical data but not updated in real time. The positive impact of model updating with observations can still be observed 10 days after the update. These simulations also suggest that parameters (hydraulic conductivity and leakage) are successfully updated: 1 and 10 day piezometric head predictions are better with than without updating of parameters. Additional experiments with a synthetic model for the same site, in which the only difference is that certain parameter values are selected as the unknown "true" conditions, show that EnKF also successfully updates unknown parameters. However, this is only the case if spatially distributed hydraulic conductivities and leakage coefficients are jointly updated and if a damping parameter is used. The mean absolute error of estimated log leakage coefficients decreased by up to 63%; for log hydraulic conductivity a decrease of up to 27% was observed. From January 2009 the method has been operational at the Water Works Zurich and showed a remarkable performance until present (October 2010).

  19. Aerodynamic forces acting on a rough rotating cylinder in a cross-flow

    NASA Astrophysics Data System (ADS)

    Bychkov, N. M.; Kovalenko, V. M.

    1981-06-01

    The forces are investigated experimentally for two values of the degree of turbulence. The experiments are carried out in a low-turbulence, subsonic wind tunnel; the Reynolds number varies between 100,000 and 600,000, and the rotation parameter, between 0 and 1 radian. The apparatus permits the registration of instantaneous forces with relatively high precision. The desired roughness is produced by covering the surface of the cylinder with emery paper. The magnitude and type of changes in the aerodynamic forces for the case of a rough cylinder are found to differ in a fundamental way from that of a smooth cylinder, a difference related to features of the flow near the wall and to the position of the separation points of the boundary layer. Increasing the degree of turbulence of the flow does not noticeably affect the aerodynamic forces of a rough cylinder in the supercritical region of Reynolds numbers.

  20. Solid oxide fuel cell having monolithic cross flow core and manifolding

    DOEpatents

    Poeppel, Roger B.; Dusek, Joseph T.

    1984-01-01

    This invention discloses a monolithic core construction having the flow passageways for the fuel and for the oxidant gases extended transverse to one another, whereby full face core manifolding can be achieved for these gases and their reaction products. The core construction provides that only anode material surround each fuel passageway and only cathode material surround each oxidant passageway, each anode and each cathode further sandwiching at spaced opposing sides electrolyte and interconnect materials to define electrolyte and interconnect walls. Webs of the cathode and anode material hold the electrolyte and interconnect walls spaced apart to define the flow passages. The composite anode and cathode wall structures are further alternately stacked on one another (with the separating electrolyte or interconnect material typically being a single common layer) whereby the fuel passageway and the oxidant passageways are disposed transverse to one another.

  1. Solid oxide fuel cell having monolithic cross flow core and manifolding

    DOEpatents

    Poeppel, R.B.; Dusek, J.T.

    1983-10-12

    This invention discloses a monolithic core construction having the flow passageways for the fuel and for the oxidant gases extended transverse to one another, whereby full face core manifolding can be achieved for these gases and their reaction products. The core construction provides that only anode material surround each fuel passageway and only cathode material surround each oxidant passageway, each anode and each cathode further sandwiching at spaced opposing sides electrolyte and interconnect materials to define electrolyte and interconnect walls. Webs of the cathode and anode material hold the electrolyte and interconnect walls spaced apart to define the flow passages. The composite anode and cathode wall structures are further alternately stacked on one another (with the separating electrolyte or interconnect material typically being a single common layer) whereby the fuel passageways and the oxidant passageways are disposed transverse to one another.

  2. Computation of a Synthetic Jet in a Turbulent Cross-Flow Boundary Layer

    NASA Technical Reports Server (NTRS)

    Rumsey, Christopher L.

    2004-01-01

    A series of unsteady Reynolds-averaged Navier-Stokes computations are performed for the flow of a synthetic jet issuing into a turbulent boundary layer through a circular orifice. This is one of the validation test cases from a synthetic jet validation workshop held in March 2004. Several numerical parameters are investigated, and the effects of three different turbulence models are explored. Both long-time-averaged and time-dependent phase-averaged results are compared to experiment. On the whole, qualitative comparisons of the mean flow quantities are fairly good. There are many differences evident in the quantitative comparisons. The calculations do not exhibit a strong dependence on the type of turbulence model employed.

  3. Study of motion of flexible eel from the wake of bluff body in a cross flow

    NASA Astrophysics Data System (ADS)

    Sin, Vai Kuong; Deng, Wen Yue; Xiao, Wei Hang

    2012-09-01

    In this research, interaction between eel and vortex shedding behind a bluff body is studied numerically, aiming to optimize the oscillation of eels by coupling with the altering vertices. Effects of different factors such as length of eel, width of bluff body and flow speed on vibration of eels are also aimed to be investigated. A 2-dimensional Fluid-Structure Interaction Model that simulates the motion of eel under vortex shedding behind a bluff body is constructed by using the computational fluid dynamics (CFD) software - COMSOL Multiphysics. Simulations based on laminar flow regime are performed and the results show that undulating motion of the eel is successfully modeled with the Fluid-Structure Interaction Model along with Arbitrary Lagrangian-Eulerian (ALE) method.

  4. Influence of differential elastic nucleon-nucleon cross section on stopping and collective flow in heavy-ion collisions at intermediate energies

    NASA Astrophysics Data System (ADS)

    Wang, Yongjia; Guo, Chenchen; Li, Qingfeng; Li, Zhuxia; Su, Jun; Zhang, Hongfei

    2016-08-01

    We considered three different nucleon-nucleon (NN) elastic differential cross sections: the Cugnon et al. parameterized differential cross section [Nucl. Instrum. Methods Phys. Res., Sect. B 111, 215 (1996), 10.1016/0168-583X(95)01384-9], the differential cross section derived from the collision term of the self-consistent relativistic Boltzmann-Uehling-Uhlenbeck equation proposed by Mao et al. [Z. Phys. A 347, 173 (1994), 10.1007/BF01292373], and the isotropic differential cross section within the newly updated version of the ultrarelativistic quantum molecular dynamics (UrQMD) model. By doing so, we investigated the influence of the differential elastic NN cross section on various observables (e.g., nuclear stopping, both the rapidity and transverse-velocity dependence of the directed and elliptic flows) in Au+Au collisions at beam energies 150, 250, 400, and 800 MeV /nucleon . By comparing calculations with those three differential cross sections, we found that the nuclear stopping power and the directed and elliptic flows are affected to some extent by the differential cross sections, and the impact of differential cross section on those observables becomes more visible as the beam energy increases. The effect on the elliptic flow difference v2n-v2H and ratio v2n/v2H of neutrons versus hydrogen isotopes (Z =1 ), which have been used as sensitive observables for probing nuclear symmetry energy at high densities, is weak.

  5. Studying the structure of a zone in which the single-phase flow moving in an annular channel with partially blocked cross section becomes spatially disturbed

    NASA Astrophysics Data System (ADS)

    Kashinskii, O. N.; Lobanov, P. D.; Kurdyumov, A. S.; Pribaturin, N. A.

    2013-05-01

    The flow of liquid in an annular channel with a partially shaded flow section is experimentally studied using the electrodiffusion method. The effect on the flow structure produced by a shutter closing one-quarter of the channel cross section is shown. An obstacle installed in the channel causes the flow to attain a 3D structure. The flow pattern in such channel differs significantly from that observed in undisturbed flow moving in an annular channel. It is revealed that the friction stress values measured on the channel's inner wall depend essentially on the azimuth angle over the channel height. With distance away from the obstacle, the influence it has on the hydrodynamic flow structure tends to decrease, but the disturbance produced by it does not die out completely even at a distance of more than 600 mm from the obstacle. Data quantitatively characterizing the disturbance of flow structure in the studied channel are presented.

  6. The Interaction of a Circular Synthetic Jet with a Cross-Flow Boundary Layer

    SciTech Connect

    D. M. McEligot; R. J. Pink; Jennifer M. Shuster; Douglas R. Smith

    2005-06-01

    The interaction of a circular synthetic jet with a laminar cross-flow boundary layer was investigated experimentally in the Matched-Index-of-Refraction flow facility at Idaho National Laboratory. Two orifice orientations were investigated, straight and inclined. For each orifice, phase-averaged and time-averaged PIV measurements were made at L◦/D◦ = 1.0 and 2.0 with ReU◦ = 250 and r = 1.12. Refractive index matching between the working fluid and the model material permitted experimental measurements of the flow field inside the actuator orifice and cavity simultaneously. At L◦/D◦ = 1.0, the vortex ring formed at the orifice during the expulsion portion of the actuator cycle blocks the boundary layer causing the flow to divert over and around the ring. This vortex ring does not escape the near-vicinity of the orifice and is subsequently re-ingested. At the same stroke, inclining the orifice axis 30◦ downstream leads to a jet comprised of a train of vortex rings that penetrates the cross-flow. At L◦/D◦ = 2.0, both the straight and inclined orifices create large discrete vortex rings that penetrate deep into the cross-flow, and consequently do not affect the boundary layer much beyond the near-field of the orifice.

  7. Numerical Simulation of Combustion and Extinction of a Solid Cylinder in Low-Speed Cross Flow

    NASA Technical Reports Server (NTRS)

    Tien, J. S.; Yang, Chin Tien

    1998-01-01

    The combustion and extinction behavior of a diffusion flame around a solid fuel cylinder (PMMA) in low-speed forced flow in zero gravity was studied numerically using a quasi-steady gas phase model. This model includes two-dimensional continuity, full Navier Stokes' momentum, energy, and species equations with a one-step overall chemical reaction and second-order finite-rate Arrhenius kinetics. Surface radiation and Arrhenius pyrolysis kinetics are included on the solid fuel surface description and a parameter Phi, representing the percentage of gas-phase conductive heat flux going into the solid, is introduced into the interfacial energy balance boundary condition to complete the description for the quasi-steady gas-phase system. The model was solved numerically using a body-fitted coordinate transformation and the SIMPLE algorithm. The effects of varying freestream velocity and Phi were studied. These parameters have a significant effect on the flame structure and extinction limits. Two flame modes were identified: envelope flame and wake flame. Two kinds of flammability limits were found: quenching at low-flow speeds due to radiative loss and blow-off at high flow speeds due to insufficient gas residence time. A flammability map was constructed showing the existence of maximum Phi above which the solid is not flammable at any freestream velocity.

  8. Crossing the divide: gene flow produces intergeneric hybrid in feral transgenic creeping bentgrass population.

    PubMed

    Zapiola, María L; Mallory-Smith, Carol A

    2012-10-01

    Gene flow is the most frequently expressed public concern related to the deregulation of transgenic events (Snow 2002; Ellstrand 2003). However, assessing the potential for transgene escape is complex because it depends on the opportunities for unintended gene flow, and establishment and persistence of the transgene in the environment (Warwick et al. 2008). Creeping bentgrass (Agrostis stolonifera L.), a turfgrass species widely used on golf courses, has been genetically engineered to be resistant to glyphosate, a nonselective herbicide. Outcrossing species, such as creeping bentgrass (CB), which have several compatible species, have greater chances for gene escape and spontaneous hybridization (i.e. natural, unassisted sexual reproduction between taxa in the field), which challenges transgene containment. Several authors have emphasized the need for evidence of spontaneous hybridization to infer the potential for gene flow (Armstrong et al. 2005). Here we report that a transgenic intergeneric hybrid has been produced as result of spontaneous hybridization of a feral-regulated transgenic pollen receptor (CB) and a nontransgenic pollen donor (rabbitfoot grass, RF, Polypogon monspeliensis (L.) Desf.). We identified an off-type transgenic seedling and confirmed it to be CB × RF intergeneric hybrid. This first report of a transgenic intergeneric hybrid produced in situ with a regulated transgenic event demonstrates the importance of considering all possible avenues for transgene spread at the landscape level before planting a regulated transgenic crop in the field. Spontaneous hybridization adds a level of complexity to transgene monitoring, containment, mitigation and remediation programmes.

  9. Identification of cross-formation flow in multireservoir systems using isotopic techniques

    SciTech Connect

    Szpakiewicz, M.

    1991-10-01

    This study was designed to add quantitative solutions to the problem of undesirable hydraulic communication which results in active fluid flow between productive horizons. Transfer of novel geochemical methods, based on effective, economic, and environmentally acceptable isotopic techniques for identification of leaking hydrocarbon reservoirs, is a major objective of this study. The effectiveness of a continuous trap's seal depends on an equilibrium between the capillary forces holding formation water in pore spaces of the seal and the buoyancy forces of the oil and gas column in a system. Therefore, some seals may leak selectively at changing pressure and temperature conditions with respect to different fluid phases (oil, gas, and water). A break in continuity of confining layers will promote relatively fast interreservoir migration of fluids. It may intensify in reservoirs subjected to high pressures during implementation of secondary and tertiary processes of recovery. Such fluid flow should result in identifiable chemical, isotopic, and often thermal anomalies in the area of an open flow path. Quantitative hydrodynamic reservoir modeling based on geochemical/isotopic and other evidence of fluid migration in a system require, however, more systematic methodological study. Such a study is being recommended in addition to a field demonstration of the method in a selected oil/gas reservoir where geochemical and production anomalies have been documented. 62 refs., 7 figs., 2 tabs.

  10. Producing monodisperse drug-loaded polymer microspheres via cross-flow membrane emulsification: the effects of polymers and surfactants.

    PubMed

    Meyer, Robert F; Rogers, W Benjamin; McClendon, Mark T; Crocker, John C

    2010-09-21

    Cross-flow membrane emulsification (XME) is a method for producing highly uniform droplets by forcing a fluid through a small orifice into a transverse flow of a second, immiscible fluid. We investigate the feasibility of using XME to produce monodisperse solid microspheres made of a hydrolyzable polymer and a hydrophobic drug, a model system for depot drug delivery applications. This entails the emulsification of a drug and polymer-loaded volatile solvent into water followed by evaporation of the solvent. We use a unique side-view visualization technique to observe the details of emulsion droplet production, providing direct information regarding droplet size, dripping frequency, wetting of the membrane surface by the two phases, neck thinning during droplet break off, and droplet deformation before and after break off. To probe the effects that dissolved polymers, surfactants, and dynamic interfacial tension may have on droplet production, we compare our results to a polymer and surfactant-free fluid system with closely matched physical properties. Comparing the two systems, we find little difference in the variation of particle size as a function of continuous phase flow rate. In contrast, at low dripping frequencies, dynamic interfacial tension causes the particle size to vary significantly with drip frequency, which is not seen in simple fluids. No effects due to shear thinning or fluid elasticity are detected. Overall, we find no significant impediments to the application of XME to forming highly uniform drug-loaded microspheres.

  11. Development of a temperature measurement system with application to a jet in a cross flow experiment

    NASA Technical Reports Server (NTRS)

    Wark, C.; Foss, J. F.

    1985-01-01

    A temperature measurement system, which allows the simultaneous sampling of up to 80 separate thermocouples, was developed. The minimum resolution for the system corresponds to + or - 0.16 C per least significant bit of the A/D converter. The time constant values lambda, for each of the 64 thermocouples, were determined experimentally at 7 mps. Software routines were used to correct the measured temperatures for the effect of lambda for each thermocouple. The temperature measurement system was utilized to study the thermal field of a heated jet discharging perpendicularly into a low and a high disturbance level cross stream for a given momentum flux ratio and for three overheated values. The peak instantaneous temperatures reveal that strong molecular diffusion was operative. Various measures of the thermal field, for the disturbed case, suggest that the jet column remains relatively compact while being buffeted by the ambient turbulence field and that its penetration, into the cross wind, is inhibited by the presence of the strong disturbance field.

  12. The T-By Tray: A plug flow, low pressure drop, high-efficiency contacting device for cross-flow columns

    SciTech Connect

    Bravo, J.L. ); Parker, B.M.; Parker, T.J. )

    1991-01-01

    This report describes the development of the T-By tray, a new tray design for cross-flow contacting of gas and liquid in absorption, stripping and distillation applications, which is designed to promote liquid plug flow and eliminate tray stagnant side zones. Two different designs, T-By I and T-By II, were tested for capacity, mass transfer efficiency and pressure drop. The T-By I design is the most successful, and offers the following advantages over sieve and valve trays: lower pressure drop per tray at equivalent open areas and weir heights, better turndown capability and a wider operating range, equivalent or higher efficiency for mass transfer, and greater vapor handling capacity. Mass transfer data from larger scale devices are needed to confirm some advantages seen in smaller columns, but the T-By tray should perform at least as well and probably better than conventional sieve and valve trays in larger diameter columns. 7 refs., 22 figs., 8 tabs.

  13. Superimposition of external oscillation to enhance heat transfer from objects in cross flow

    NASA Astrophysics Data System (ADS)

    Bourisli, Raed

    2012-11-01

    Laminar flow around objects gives rise to the recurrent build-up and release of vortices on alternate sides of the objects over a wide range of Reynolds numbers. Inherent disturbance of the otherwise uniform flow and temperature fields plays an important role in many structural, hydrodynamic as well as thermal aspects of situations where it is present. For example, the local disturbance of the velocity field leads to subsequent instability in the temperature field, causing variations in local Nusselt number, heat flux and surface temperature, among other things. One can take advantage of this phenomenon in many applications such as the cooling of electronic equipment. It is suggested here that the intensity of the outlined vortex shedding phenomenon can be deepened if an external movement is superimposed on the velocity of the structure or any nearby object. Numerical test of several objects rotated in-plane: cylinders, squares, triangles and horizontal plates, are performed. The key physical observation is the relative magnitudes of the heat transfer due to natural vortex shedding compared to the added value obtained by superimposing an additional external source of oscillation. A realistic case of electronics chips cooling is presented to show the effect of matching the natural frequency of vortex shedding by that of the inhomogeneity (Video: 0-9 s optimum; 9-18 non-). In this case, vortex shedding from the plates plays a smaller role in disturbing the flow, hindering it at times. When the two frequencies coincide, however, in-phase shedding leads to more efficient heat transfer.

  14. Analysis of parameters of air passing through the rain zone in a cross-flow

    NASA Astrophysics Data System (ADS)

    Dvořák, Lukáš; Čížek, Jan; Nožička, Jiří

    2015-05-01

    The research in the field of cooling towers shows that a rigorous determination of each parameter of air passing through areas with water drops is increasingly important. The transfer of heat, mass and momentum is represented, on the side of the air, as temperature and humidity increase and static pressure decrease due to the interaction between the flowing air and falling drops. The present article focuses on the description of the experimental setup allowing the measurement of these parameters on both the air and the water side, and possible ways to analyze measured values.

  15. Quick-change filter cartridge

    DOEpatents

    Rodgers, John C.; McFarland, Andrew R.; Ortiz, Carlos A.

    1995-01-01

    A quick-change filter cartridge. In sampling systems for measurement of airborne materials, a filter element is introduced into the sampled airstream such that the aerosol constituents are removed and deposited on the filter. Fragile sampling media often require support in order to prevent rupture during sampling, and careful mounting and sealing to prevent misalignment, tearing, or creasing which would allow the sampled air to bypass the filter. Additionally, handling of filter elements may introduce cross-contamination or exposure of operators to toxic materials. Moreover, it is desirable to enable the preloading of filter media into quick-change cartridges in clean laboratory environments, thereby simplifying and expediting the filter-changing process in the field. The quick-change filter cartridge of the present invention permits the application of a variety of filter media in many types of instruments and may also be used in automated systems. The cartridge includes a base through which a vacuum can be applied to draw air through the filter medium which is located on a porous filter support and held there by means of a cap which forms an airtight seal with the base. The base is also adapted for receiving absorbing media so that both particulates and gas-phase samples may be trapped for investigation, the latter downstream of the aerosol filter.

  16. Determination of Diclofenac on a Dysprosium Nanowire- Modified Carbon Paste Electrode Accomplished in a Flow Injection System by Advanced Filtering

    PubMed Central

    Daneshgar, Parandis; Norouzi, Parviz; Ganjali, Mohammad Reza; Dinarvand, Rasoul; Moosavi-Movahedi, Ali Akbar

    2009-01-01

    A new detection technique called Fast Fourier Transform Square-Wave Voltammetry (FFT SWV) is based on measurements of electrode admittance as a function of potential. The response of the detector (microelectrode), which is generated by a redox processes, is fast, which makes the method suitable for most applications involving flowing electrolytes. The carbon paste electrode was modified by nanostructures to improve sensitivity. Synthesized dysprosium nanowires provide a more effective nanotube-like surface [1-4] so they are good candidates for use as a modifier for electrochemical reactions. The redox properties of diclofenac were used for its determination in human serum and urine samples. The support electrolyte that provided a more defined and intense peak current for diclofenac determination was a 0.05 mol L−1 acetate buffer pH = 4.0. The drug presented an irreversible oxidation peak at 850 mV vs. Ag/AgCl on a modified nanowire carbon paste electrode which produced high current and reduced the oxidation potential by about 100 mV. Furthermore, the signal-to-noise ratio was significantly increased by application of a discrete Fast Fourier Transform (FFT) method, background subtraction and two-dimensional integration of the electrode response over a selected potential range and time window. To obtain the much sensivity the effective parameters such as frequency, amplitude and pH was optimized. As a result, CDL of 2.0 × 10−9 M and an LOQ of 5.0 × 10−9 M were found for the determination for diclofenac. A good recovery was obtained for assay spiked urine samples and a good quantification of diclofenac was achieved in a commercial formulation. PMID:22408485

  17. OPTIMIZATION OF ADVANCED FILTER SYSTEMS

    SciTech Connect

    R.A. Newby; M.A. Alvin; G.J. Bruck; T.E. Lippert; E.E. Smeltzer; M.E. Stampahar

    2002-06-30

    Two advanced, hot gas, barrier filter system concepts have been proposed by the Siemens Westinghouse Power Corporation to improve the reliability and availability of barrier filter systems in applications such as PFBC and IGCC power generation. The two hot gas, barrier filter system concepts, the inverted candle filter system and the sheet filter system, were the focus of bench-scale testing, data evaluations, and commercial cost evaluations to assess their feasibility as viable barrier filter systems. The program results show that the inverted candle filter system has high potential to be a highly reliable, commercially successful, hot gas, barrier filter system. Some types of thin-walled, standard candle filter elements can be used directly as inverted candle filter elements, and the development of a new type of filter element is not a requirement of this technology. Six types of inverted candle filter elements were procured and assessed in the program in cold flow and high-temperature test campaigns. The thin-walled McDermott 610 CFCC inverted candle filter elements, and the thin-walled Pall iron aluminide inverted candle filter elements are the best candidates for demonstration of the technology. Although the capital cost of the inverted candle filter system is estimated to range from about 0 to 15% greater than the capital cost of the standard candle filter system, the operating cost and life-cycle cost of the inverted candle filter system is expected to be superior to that of the standard candle filter system. Improved hot gas, barrier filter system availability will result in improved overall power plant economics. The inverted candle filter system is recommended for continued development through larger-scale testing in a coal-fueled test facility, and inverted candle containment equipment has been fabricated and shipped to a gasifier development site for potential future testing. Two types of sheet filter elements were procured and assessed in the program

  18. Fiber length and orientation prevent migration in fluid filters

    NASA Technical Reports Server (NTRS)

    Reiman, P. A.

    1966-01-01

    Stainless steel fiber web filter resists fiber migration which causes contamination of filtered fluids. This filter is capable of holding five times more particulate matter before arbitrary cutoff pressure drop and shows excellent retention in fuel flow at high rates.

  19. Protein overproduction in Escherichia coli: RNA stabilization, cell disruption and recovery with a cross-flow microfiltration membrane.

    PubMed

    Chan, W K; Belfort, M; Belfort, G

    1991-05-01

    After optimizing overproduction of a heterologous gene product (chloramphenicol acetyltransferase, CAT) using an RNA stabilization vector * in Escherichia coli (Chan et al., 1988), a single step cell disruption and recovery method * for obtaining a product stream essentially free of cell debris was developed. The behavior of an RNA stabilization plasmid (pKTN-CAT) containing stabilizing intron RNA was investigated in two different media both in batch and chemostat modes. CAT production of pKTN-CAT was consistently higher (3- to 7-fold) than that of the control lacking the stabilization sequences (pK-CAT). Highest CAT production was observed for cells grown in minimal medium in batch mode and induced for CAT expression early in growth. CAT production of cells grown in the chemostat mode exhibited an optimal dilution rate of about 0.1 h-1. Enhancement of protein production by pKTN-CAT as compared to pK-CAT tended to be higher when grown in rich medium rather than in minimal medium. Presence of the RNA stabilization plasmid did not significantly alter the growth rate of the cell. Using a combination of chemical treatment (1 mM EDTA) and shear stress resulting from cross-flow in a stainless steel microfiltration membrane *, CAT was released into the medium through disruption of the E. coli cells. The permeate flux increased from 2000 to 9000 kg m-2 h-1 with increasing axial Reynolds number from 10,000 to 60,000 or increasing mean shear stress from 12 to 47 Pa. The turbidity of the permeate was approximately 4% that of the retentate over this range of axial flow rates, indicating excellent removal of cell debris. Also, the concentration of CAT in the permeate was equal to that in the retentate over this range of axial flow rates, indicating complete passage of protein through the membrane. Thus, using a combination of chemical treatment and fluid-induced shear stress in a cross-flow membrane module, we were able to disrupt and recover the heterologous protein in a

  20. Ceramic fiber reinforced filter

    DOEpatents

    Stinton, David P.; McLaughlin, Jerry C.; Lowden, Richard A.

    1991-01-01

    A filter for removing particulate matter from high temperature flowing fluids, and in particular gases, that is reinforced with ceramic fibers. The filter has a ceramic base fiber material in the form of a fabric, felt, paper of the like, with the refractory fibers thereof coated with a thin layer of a protective and bonding refractory applied by chemical vapor deposition techniques. This coating causes each fiber to be physically joined to adjoining fibers so as to prevent movement of the fibers during use and to increase the strength and toughness of the composite filter. Further, the coating can be selected to minimize any reactions between the constituents of the fluids and the fibers. A description is given of the formation of a composite filter using a felt preform of commercial silicon carbide fibers together with the coating of these fibers with pure silicon carbide. Filter efficiency approaching 100% has been demonstrated with these filters. The fiber base material is alternately made from aluminosilicate fibers, zirconia fibers and alumina fibers. Coating with Al.sub.2 O.sub.3 is also described. Advanced configurations for the composite filter are suggested.

  1. FUNDAMENTAL AREAS OF PHENOMENOLOGY (INCLUDING APPLICATIONS): Suppression of Nonlinear Patterning Effect in Wavelength Conversion Based on Transient Cross-Phase Modulation in Semiconductor Optical Amplifier Assisted with a Detuning Filter

    NASA Astrophysics Data System (ADS)

    Zhou, En-Bo; Zhang, Xin-Liang; Yu, Yu; Huang, De-Xiu

    2009-03-01

    Nonlinear patterning (NLP) effect in wavelength conversion based on transient cross-phase modulation (XPM) in semiconductor optical amplifier (SOA) assisted with a detuning filter is theoretically investigated. A non-adiabatic model is used to estimate the ultrafast dynamics of gain, phase and electron temperature in the SOA. Simulation results show that the NLP can be greatly suppressed by introducing an assist light, especially for the probe wavelength distant from gain peak. Furthermore, the results also indicate that the improvement is more evident for long wavelength probe light and assist light in counter-propagating configuration.

  2. Development and Deployment of a Full-Scale Cross-Flow Filtration System for Treatment of Liquid Low-Level Waste at Oak Ridge National Laboratory

    SciTech Connect

    Kent, T.E.

    2000-05-12

    , valves, sensors, monitors, controls, shielding, and containment) functioned very well during each campaign. Evaluation of the Endress+Hauser Promass 63F Mass Flowmeter (a secondary objective of the project) indicated reasonably accurate and reliable performance. This instrument was installed on the feed pipeline for the SLS system, and it provided very accurate mass flow and density data, and reasonably accurate solids content data. Near the end of tank W-31 processing, the solids content of the feed to the SLS system increased to a very high concentration. This behavior was caused by the increased mixing of liquid and sludge phases within MVST Tank 31 as the level of liquid being decanted from the tank approached the level of the settled sludge. The physical properties of the heavy sludge caused some difficulties in draining and flushing of the system. Other minor equipment problems were encountered, but none resulted in significant downtime or safety issues. Operational data collected during the campaign were useful in evaluating the performance of the system. The 50-ft{sup 2} cross-flow filter was designed to provide filtrate at the rate of 1 to 5 gal/min (flux range of 0.02 to 0.1 gal min{sup -1} ft{sup -2}) of filtrate, and actual production was between 0.6 and 8.0 gal/min (flux range of 0.012 to 0.16 gal min{sup -1} ft{sup -2}). Additional operating data will be needed, however, to assess the long-term performance of the system with wider variations in the composition of the tank waste feed. The SLS will be employed in further processing campaigns during FY 2000, and more performance data will be collected.

  3. Numerical Analysis of a Pulse Detonation Cross Flow Heat Load Experiment

    NASA Technical Reports Server (NTRS)

    Paxson, Daniel E.; Naples, Andrew .; Hoke, John L.; Schauer, Fred

    2011-01-01

    A comparison between experimentally measured and numerically simulated, time-averaged, point heat transfer rates in a pulse detonation (PDE) engine is presented. The comparison includes measurements and calculations for heat transfer to a cylinder in crossflow and to the tube wall itself using a novel spool design. Measurements are obtained at several locations and under several operating conditions. The measured and computed results are shown to be in substantial agreement, thereby validating the modeling approach. The model, which is based in computational fluid dynamics (CFD) is then used to interpret the results. A preheating of the incoming fuel charge is predicted, which results in increased volumetric flow and subsequent overfilling. The effect is validated with additional measurements.

  4. Microbial responses to changes in flow status in temporary headwater streams: a cross-system comparison.

    PubMed

    Febria, Catherine M; Hosen, Jacob D; Crump, Byron C; Palmer, Margaret A; Williams, D Dudley

    2015-01-01

    Microbial communities are responsible for the bulk of biogeochemical processing in temporary headwater streams, yet there is still relatively little known about how community structure and function respond to periodic drying. Moreover, the ability to sample temporary habitats can be a logistical challenge due to the limited capability to measure and predict the timing, intensity and frequency of wet-dry events. Unsurprisingly, published datasets on microbial community structure and function are limited in scope and temporal resolution and vary widely in the molecular methods applied. We compared environmental and microbial community datasets for permanent and temporary tributaries of two different North American headwater stream systems: Speed River (Ontario, Canada) and Parkers Creek (Maryland, USA). We explored whether taxonomic diversity and community composition were altered as a result of flow permanence and compared community composition amongst streams using different 16S microbial community methods (i.e., T-RFLP and Illumina MiSeq). Contrary to our hypotheses, and irrespective of method, community composition did not respond strongly to drying. In both systems, community composition was related to site rather than drying condition. Additional network analysis on the Parkers Creek dataset indicated a shift in the central microbial relationships between temporary and permanent streams. In the permanent stream at Parkers Creek, associations of methanotrophic taxa were most dominant, whereas associations with taxa from the order Nitrospirales were more dominant in the temporary stream, particularly during dry conditions. We compared these results with existing published studies from around the world and found a wide range in community responses to drying. We conclude by proposing three hypotheses that may address contradictory results and, when tested across systems, may expand understanding of the responses of microbial communities in temporary streams to

  5. Microbial responses to changes in flow status in temporary headwater streams: a cross-system comparison

    PubMed Central

    Febria, Catherine M.; Hosen, Jacob D.; Crump, Byron C.; Palmer, Margaret A.; Williams, D. Dudley

    2015-01-01

    Microbial communities are responsible for the bulk of biogeochemical processing in temporary headwater streams, yet there is still relatively little known about how community structure and function respond to periodic drying. Moreover, the ability to sample temporary habitats can be a logistical challenge due to the limited capability to measure and predict the timing, intensity and frequency of wet-dry events. Unsurprisingly, published datasets on microbial community structure and function are limited in scope and temporal resolution and vary widely in the molecular methods applied. We compared environmental and microbial community datasets for permanent and temporary tributaries of two different North American headwater stream systems: Speed River (Ontario, Canada) and Parkers Creek (Maryland, USA). We explored whether taxonomic diversity and community composition were altered as a result of flow permanence and compared community composition amongst streams using different 16S microbial community methods (i.e., T-RFLP and Illumina MiSeq). Contrary to our hypotheses, and irrespective of method, community composition did not respond strongly to drying. In both systems, community composition was related to site rather than drying condition. Additional network analysis on the Parkers Creek dataset indicated a shift in the central microbial relationships between temporary and permanent streams. In the permanent stream at Parkers Creek, associations of methanotrophic taxa were most dominant, whereas associations with taxa from the order Nitrospirales were more dominant in the temporary stream, particularly during dry conditions. We compared these results with existing published studies from around the world and found a wide range in community responses to drying. We conclude by proposing three hypotheses that may address contradictory results and, when tested across systems, may expand understanding of the responses of microbial communities in temporary streams to

  6. Effectiveness of cross-flow microfiltration for removal of microorganisms associated with unpasteurized liquid egg white from process plant.

    PubMed

    Mukhopadhyay, S; Tomasula, P M; Van Hekken, D; Luchansky, J B; Call, J E; Porto-Fett, A

    2009-08-01

    Thermal preservation is used by the egg industry to ensure the microbiological safety of liquid egg white (LEW); however, it does not eliminate all microorganisms and impairs some of the delicate functional properties of LEW. In this study, a pilot-scale cross-flow microfiltration (MF) process was designed to remove the natural microflora present in commercial LEW, obtained from a local egg-breaking plant, while maintaining the nutritional and functional properties of the LEW. LEW, containing approximately 10(6 +/- 1.7) colony forming units (CFU) per milliliter of total aerobic bacteria, was microfiltered using a ceramic membrane with a nominal pore size of 1.4 microm, at a cross-flow velocity of 6 m/s. To facilitate MF, LEW was screened, homogenized, and then diluted (1 : 2, w/w) with distilled water containing 0.5% sodium chloride. Homogenized LEW was found to have a threefold lower viscosity than unhomogenized LEW. Influence of MF temperature (25 and 40 degrees C) and pH (6 and 9) on permeate flux, transmission of egg white nutrients across the membrane, and microbial removal efficiency were evaluated. The pH had a significantly greater influence on permeate flux than temperature. Permeate flux increased by almost 148% when pH of LEW was adjusted from pH 9 to pH 6 at 40 degrees C. Influence of temperature on permeate flux, at a constant pH, however, was found to be inconclusive. Microbial removal efficiency was at least 5 log(10) CFU/mL. Total protein and SDS-PAGE analysis indicated that this MF process did not alter the protein composition of the permeate, compared to that of the feed LEW, and that the foaming properties of LEW were retained in the postfiltered samples. PMID:19723218

  7. The feasibility of an up-flow partially aerated biological filter (U-PABF) for nitrogen and COD removal from domestic wastewater.

    PubMed

    Tao, Chen; Peng, Tong; Feng, Chuanping; Chen, Nan; Hu, Qili; Hao, Chunbo

    2016-10-01

    An up-flow partially aerated biological filter (U-PABF) was developed to study the removal of nitrogen and chemical oxygen demand (COD) from synthetic domestic wastewater. The removal of NH4(+)-N was primarily attributed to adsorption in the zeolite U-PABF and to bioprocesses in the ceramic U-PABF. When the hydraulic retention time (HRT) was 5.2h, the ceramic U-PABF achieved a good performance and the NH4(+)-N, total nitrogen (TN), and COD removal efficiency reached 99.08±8.79%, 72.83±0.68%, and 89.38±1.04%, respectively. The analysis of NH4(+)-N, NO3(-)-N, NO2(-)-N, and TN at different depths revealed the simultaneous existence of nitrification-denitrification, and anaerobic ammonium oxidation (anammox) in ceramic U-PABF. Illumina pyrosequencing confirmed the existence of Planctomycetes, which are responsible for anammox. The results indicated that the nitrification-denitrification and anammox all contributed to the high removal of NH4(+)-N, TN, and COD in the U-PABF. PMID:27372011

  8. The feasibility of an up-flow partially aerated biological filter (U-PABF) for nitrogen and COD removal from domestic wastewater.

    PubMed

    Tao, Chen; Peng, Tong; Feng, Chuanping; Chen, Nan; Hu, Qili; Hao, Chunbo

    2016-10-01

    An up-flow partially aerated biological filter (U-PABF) was developed to study the removal of nitrogen and chemical oxygen demand (COD) from synthetic domestic wastewater. The removal of NH4(+)-N was primarily attributed to adsorption in the zeolite U-PABF and to bioprocesses in the ceramic U-PABF. When the hydraulic retention time (HRT) was 5.2h, the ceramic U-PABF achieved a good performance and the NH4(+)-N, total nitrogen (TN), and COD removal efficiency reached 99.08±8.79%, 72.83±0.68%, and 89.38±1.04%, respectively. The analysis of NH4(+)-N, NO3(-)-N, NO2(-)-N, and TN at different depths revealed the simultaneous existence of nitrification-denitrification, and anaerobic ammonium oxidation (anammox) in ceramic U-PABF. Illumina pyrosequencing confirmed the existence of Planctomycetes, which are responsible for anammox. The results indicated that the nitrification-denitrification and anammox all contributed to the high removal of NH4(+)-N, TN, and COD in the U-PABF.

  9. Protection of biomass from snail overgrazing in a trickling filter using sponge media as a biomass carrier: down-flow hanging sponge system.

    PubMed

    Onodera, Takashi; Syutsubo, Kazuaki; Yoochatchaval, Wilasinee; Sumino, Haruhiko; Mizuochi, Motoyuki; Harada, Hideki

    2015-01-01

    This study investigated down-flow hanging sponge (DHS) technology as a promising trickling filter (TF) using sponge media as a biomass carrier with an emphasis on protection of the biomass against macrofauna overgrazing. A pilot-scale DHS reactor fed with low-strength municipal sewage was operated under ambient temperature conditions for 1 year at a sewage treatment plant in Bangkok, Thailand. The results showed that snails (macrofauna) were present on the surface of the sponge media, but could not enter into it, because the sponge media with smaller pores physically protected the biomass from the snails. As a result, the sponge media maintained a dense biomass, with an average value of 22.3 gVSS/L sponge (58.1 gTSS/L sponge) on day 370. The snails could graze biomass on the surface of the sponge media. The DHS reactor process performance was also successful. The DHS reactor requires neither chemical treatments nor specific operations such as flooding for snail control. Overall, the results of this study indicate that the DHS reactor is able to protect biomass from snail overgrazing.

  10. Protection of biomass from snail overgrazing in a trickling filter using sponge media as a biomass carrier: down-flow hanging sponge system.

    PubMed

    Onodera, Takashi; Syutsubo, Kazuaki; Yoochatchaval, Wilasinee; Sumino, Haruhiko; Mizuochi, Motoyuki; Harada, Hideki

    2015-01-01

    This study investigated down-flow hanging sponge (DHS) technology as a promising trickling filter (TF) using sponge media as a biomass carrier with an emphasis on protection of the biomass against macrofauna overgrazing. A pilot-scale DHS reactor fed with low-strength municipal sewage was operated under ambient temperature conditions for 1 year at a sewage treatment plant in Bangkok, Thailand. The results showed that snails (macrofauna) were present on the surface of the sponge media, but could not enter into it, because the sponge media with smaller pores physically protected the biomass from the snails. As a result, the sponge media maintained a dense biomass, with an average value of 22.3 gVSS/L sponge (58.1 gTSS/L sponge) on day 370. The snails could graze biomass on the surface of the sponge media. The DHS reactor process performance was also successful. The DHS reactor requires neither chemical treatments nor specific operations such as flooding for snail control. Overall, the results of this study indicate that the DHS reactor is able to protect biomass from snail overgrazing. PMID:25746642

  11. A microchip filter device incorporating slit arrays and 3-D flow for detection of circulating tumor cells using CAV1-EpCAM conjugated microbeads.

    PubMed

    Kim, Yeon Jeong; Koo, Gi-Bang; Lee, June-Young; Moon, Hui-Sung; Kim, Dong-Gun; Lee, Da-Gyum; Lee, Ju-Yeon; Oh, Jin Ho; Park, Jong-Myeon; Kim, Minseok S; Woo, Hyun Goo; Kim, Seung-Il; Kang, Pilsung; Choi, Wonshik; Sim, Tae Seok; Park, Woong-Yang; Lee, Jeong-Gun; Kim, You-Sun

    2014-08-01

    Circulating tumor cells (CTCs) are rare cells and the presence of these cells may indicate a poor prognosis and a high potential for metastasis. Despite highly promising clinical applications, CTCs have not been investigated thoroughly, due to many technical limitations faced in their isolation and identification. Current CTC detection techniques mostly take the epithelial marker epithelial cell adhesion molecule (EpCAM), however, accumulating evidence suggests that CTCs show heterogeneous EpCAM expression due to the epithelial-to-mesenchymal transition (EMT). In this study, we report that a microchip filter device incorporating slit arrays and 3-dimensional flow that can separate heterogeneous population of cells with marker for CTCs. To select target we cultured breast cancer cells under prolonged mammosphere culture conditions which induced EMT phenotype. Under these conditions, cells show upregulation of caveolin1 (CAV1) but down-regulation of EpCAM expression. The proposed device which contains CAV1-EpCAM conjugated bead has several tens of times increased throughput. More importantly, this platform enables the enhanced capture yield from metastatic breast cancer patients and obtained cells that expressed various EMT markers. Further understanding of these EMT-related phenotypes will lead to improved detection techniques and may provide an opportunity to develop therapeutic strategies for effective treatment and prevention of cancer metastasis.

  12. Filtering apparatus

    DOEpatents

    Haldipur, G.B.; Dilmore, W.J.

    1992-09-01

    A vertical vessel is described having a lower inlet and an upper outlet enclosure separated by a main horizontal tube sheet. The inlet enclosure receives the flue gas from a boiler of a power system and the outlet enclosure supplies cleaned gas to the turbines. The inlet enclosure contains a plurality of particulate-removing clusters, each having a plurality of filter units. Each filter unit includes a filter clean-gas chamber defined by a plate and a perforated auxiliary tube sheet with filter tubes suspended from each tube sheet and a tube connected to each chamber for passing cleaned gas to the outlet enclosure. The clusters are suspended from the main tube sheet with their filter units extending vertically and the filter tubes passing through the tube sheet and opening in the outlet enclosure. The flue gas is circulated about the outside surfaces of the filter tubes and the particulate is absorbed in the pores of the filter tubes. Pulses to clean the filter tubes are passed through their inner holes through tubes free of bends which are aligned with the tubes that pass the clean gas. 18 figs.

  13. Filtering apparatus

    DOEpatents

    Haldipur, Gaurang B.; Dilmore, William J.

    1992-01-01

    A vertical vessel having a lower inlet and an upper outlet enclosure separated by a main horizontal tube sheet. The inlet enclosure receives the flue gas from a boiler of a power system and the outlet enclosure supplies cleaned gas to the turbines. The inlet enclosure contains a plurality of particulate-removing clusters, each having a plurality of filter units. Each filter unit includes a filter clean-gas chamber defined by a plate and a perforated auxiliary tube sheet with filter tubes suspended from each tube sheet and a tube connected to each chamber for passing cleaned gas to the outlet enclosure. The clusters are suspended from the main tube sheet with their filter units extending vertically and the filter tubes passing through the tube sheet and opening in the outlet enclosure. The flue gas is circulated about the outside surfaces of the filter tubes and the particulate is absorbed in the pores of the filter tubes. Pulses to clean the filter tubes are passed through their inner holes through tubes free of bends which are aligned with the tubes that pass the clean gas.

  14. In-service filter testing

    SciTech Connect

    Terada, K.; Woodard, R.W.; Jensen, R.T.

    1985-04-29

    This report contains the observations, test results, and conclusions of three separate in-service tests beginning in November 1979 and concluding in September 1983. The in-service tests described in this report produced encouraging results on filters constructed with fiberglass medium containing 5% Nomex and separators of aluminum foil coated with a thin film of vinyl-epoxy polymer. Filters containing medium with Kevlar fiber additives demonstrated they merited further evaluation. Other types of filters tested include separatorless filters (Flanders SuperFlow) and one filter with fiberglass separators. Asbestos-containing filters were used for comparison until their supply was exhausted. All filters tested were judged to have performed satisfactorily under the test conditions.

  15. Comparison of simple, small, full-scale sewage treatment systems in Brazil: UASB-maturation ponds-coarse filter; UASB-horizontal subsurface-flow wetland; vertical-flow wetland (first stage of French system).

    PubMed

    von Sperling, M

    2015-01-01

    This paper presents a comparison between three simple sewage treatment lines involving natural processes: (a) upflow anaerobic sludge blanket (UASB) reactor-three maturation ponds in series-coarse rock filter; (b) UASB reactor-horizontal subsurface-flow constructed wetland; and (c) vertical-flow constructed wetlands treating raw sewage (first stage of the French system). The evaluation was based on several years of practical experience with three small full-scale plants receiving the same influent wastewater (population equivalents of 220, 60 and 100 inhabitants) in the city of Belo Horizonte, Brazil. The comparison included interpretation of concentrations and removal efficiencies based on monitoring data (organic matter, solids, nitrogen, phosphorus, coliforms and helminth eggs), together with an evaluation of practical aspects, such as land and volume requirements, sludge production and handling, plant management, clogging and others. Based on an integrated evaluation of all aspects involved, it is worth emphasizing that each system has its own specificities, and no generalization can be made on the best option. The overall conclusion is that the three lines are suitable for sewage treatment in small communities in warm-climate regions.

  16. Comparison of simple, small, full-scale sewage treatment systems in Brazil: UASB-maturation ponds-coarse filter; UASB-horizontal subsurface-flow wetland; vertical-flow wetland (first stage of French system).

    PubMed

    von Sperling, M

    2015-01-01

    This paper presents a comparison between three simple sewage treatment lines involving natural processes: (a) upflow anaerobic sludge blanket (UASB) reactor-three maturation ponds in series-coarse rock filter; (b) UASB reactor-horizontal subsurface-flow constructed wetland; and (c) vertical-flow constructed wetlands treating raw sewage (first stage of the French system). The evaluation was based on several years of practical experience with three small full-scale plants receiving the same influent wastewater (population equivalents of 220, 60 and 100 inhabitants) in the city of Belo Horizonte, Brazil. The comparison included interpretation of concentrations and removal efficiencies based on monitoring data (organic matter, solids, nitrogen, phosphorus, coliforms and helminth eggs), together with an evaluation of practical aspects, such as land and volume requirements, sludge production and handling, plant management, clogging and others. Based on an integrated evaluation of all aspects involved, it is worth emphasizing that each system has its own specificities, and no generalization can be made on the best option. The overall conclusion is that the three lines are suitable for sewage treatment in small communities in warm-climate regions. PMID:25714630

  17. Cross-type optical separation of elastic oblate capsules in a uniform flow

    SciTech Connect

    Chang, Cheong Bong; Sung, Hyung Jin; Huang, Wei-Xi

    2015-01-21

    The dynamic behavior of an elastic capsule with an initially oblate spheroidal shape during cross-type optical separation was numerically investigated. The penalty immersed boundary method was adopted for the fluid-membrane interaction, and the optical force calculation was conducted by using the ray optics method including the ray-surface intersection algorithm. The oblate elastic capsule of b/a = 0.5 with different surface Young's moduli and different initial inclination angles was considered. The oblate capsule with higher surface Young's moduli was less deformed, and was more migrated for each initial inclination angle. Unlike the oblate rigid particle, the initially inclined capsules with moderate inclination angles were similarly migrated since the oblate elastic capsule was deformed during rotation near the laser beam axis. The oblate capsules can be separated according to the surface Young's modulus, except for nearly non-inclined capsules. As the fluid velocity decreased, the migration distance increased. The maximum deformation parameter was insensitive to the fluid velocity. Furthermore, a new dimensionless number (S{sub ec}) was introduced to predict the migration distance of the oblate elastic capsule.

  18. On the effects of improved cross-section representation in one-dimensional flow routing models applied to ephemeral rivers

    NASA Astrophysics Data System (ADS)

    Hutton, Christopher J.; Brazier, Richard E.; Nicholas, Andrew P.; Nearing, Mark

    2012-04-01

    Flash floods are an important component of the semiarid hydrological cycle, and provide the potential for groundwater recharge as well as posing a dangerous natural hazard. A number of catchment models have been applied to flash flood prediction; however, in general they perform poorly. This study has investigated whether the incorporation of light detection and ranging (lidar) derived data into the structure of a 1-D flow routing model can improve the prediction of flash floods in ephemeral channels. Two versions of this model, one based on an existing trapezoidal representation of cross-section morphology (K-Tr), and one that uses lidar data (K-Li) were applied to 5 discrete runoff events measured at two locations on the main channel of The Walnut Gulch Experimental Watershed, United States. In general, K-Li showed improved performance in comparison to K-Tr, both when each model was calibrated to individual events and during an evaluation phase when the models (and parameter sets) were applied across events. Sensitivity analysis identified that the K-Li model also had more consistency in behavioral parameter sets across runoff events. In contrast, parameter interaction within K-Tr resulted in poorly constrained behavioral parameter sets across the multidimensional parameter space. These results, revealed with a modeling focus on the structure of a particular element of a distributed catchment model, suggest that lidar derived cross-section morphology can lead to improved, and more robust flash flood prediction.

  19. The ground vortex flow field associated with a jet in a cross flow impinging on a ground plane for uniform and annular turbulent axisymmetric jets. M.S. Thesis

    NASA Technical Reports Server (NTRS)

    Cavage, William M.; Kuhlman, John M.

    1993-01-01

    An experimental study was conducted of the impingement of a single circular jet on a ground plane in a cross flow. This geometry is a simplified model of the interaction of propulsive jet exhaust from a V/STOL aircraft with the ground in forward flight. Jets were oriented normal to the cross flow and ground plane. Jet size, cross flow-to-jet velocity ratio, ground plane-to-jet board spacing, and jet exit turbulence level and mean velocity profile shape were all varied to determine their effects on the size of the ground vortex interaction region which forms on the ground plane, using smoke injection into the jet. Three component laser Doppler velocimeter measurements were made with a commercial three color system for the case of a uniform jet with exit spacing equal to 5.5 diameters and cross flow-to-jet velocity ratio equal to 0.11. The flow visualization data compared well for equivalent runs of the same nondimensional jet exit spacing and the same velocity ratio for different diameter nozzles, except at very low velocity ratios and for the larger nozzle, where tunnel blockage became significant. Variation of observed ground vortex size with cross flow-to-jet velocity ratio was consistent with previous studies. Observed effects of jet size and ground plane-to-jet board spacing were relatively small. Jet exit turbulence level effects were also small. However, an annular jet with a low velocity central core was found to have a significantly smaller ground vortex than an equivalent uniform jet at the same values of cross flow-to-jet velocity ratio and jet exit-to-ground plane spacing. This may suggest a means of altering ground vortex behavior somewhat, and points out the importance of proper simulation of jet exit velocity conditions. LV data indicated unsteady turbulence levels in the ground vortex in excess of 70 percent.

  20. Velocity field of a round jet in a cross flow for various jet injection angles and velocity ratios. [Langley V/STOL tunnel

    NASA Technical Reports Server (NTRS)

    Fearn, R. L.; Weston, R. P.

    1979-01-01

    A subsonic round jet injected from a flat plate into a subsonic crosswind of the same temperature was investigated. Velocity and pressure measurements in planes perpendicular to the path of the jet were made for nominal jet injection angles of 45 deg, 60 deg, 75 deg, 90 deg, and 105 deg and for jet/cross flow velocity ratios of four and eight. The velocity measurements were obtained to infer the properties of the vortex pair associated with a jet in a cross flow. Jet centerline and vortex trajectories were determined and fit with an empirical equation that includes the effects of jet injection angle, jet core length, and jet/cross flow velocity ratios.