Sample records for gas centrifuge theory

  1. THE THEORY OF URANIUM ENRICHMENT BY THE GAS CENTRIFUGE

    SciTech Connect

    Olander, Donald R.

    1981-03-01

    Onsager's analysis of the hydrodynamics of fluid circulation in the boundary layer on the rotor wall of a gas centrifuge is reviewed. The description of the flow in the boundary layers on the top and bottom end caps due to Carrier and Maslen is summarized. The method developed by Wood and Morton of coupling the flow models in the rotor wall and end cap boundary layers to complete the hydrodynamic analysis of the centrifuge is presented. Mechanical and thermal methods of driving the internal gas circulation are described. The isotope enrichment which results from the superposition of the elementary separation effect due to the centrifugal field in the gas and its internal circulation is analyzed by the Onsager-Cohen theory. The performance function representing the optimized separative power of a centrifuge as a function of throughput and cut is calculated for several simplified internal flow models. The use of asymmetric ideal cascades to exploit the distinctive features of centrifuge performance functions is illustrated.

  2. Valve for gas centrifuges

    DOEpatents

    Hahs, C.A.; Rurbage, C.H.

    1982-03-17

    The invention is pneumatically operated valve assembly for simulatenously (1) closing gas-transfer lines connected to a gas centrifuge or the like and (2) establishing a recycle path between two on the lines so closed. The value assembly is especially designed to be compact, fast-acting, reliable, and comparatively inexpensive. It provides large reductions in capital costs for gas-centrifuge cascades.

  3. Valve for gas centrifuges

    DOEpatents

    Hahs, Charles A. (Oak Ridge, TN); Burbage, Charles H. (Oak Ridge, TN)

    1984-01-01

    The invention is a pneumatically operated valve assembly for simultaneously (1) closing gas-transfer lines connected to a gas centrifuge or the like and (2) establishing a recycle path between two of the lines so closed. The valve assembly is especially designed to be compact, fast-acting, reliable, and comparatively inexpensive. It provides large reductions in capital costs for gas-centrifuge cascades.

  4. Gas Centrifuges and Nuclear Proliferation

    SciTech Connect

    Albright, David

    2004-09-15

    Gas centrifuges have been an ideal enrichment method for a wide variety of countries. Many countries have built gas centrifuges to make enriched uranium for peaceful nuclear purposes. Other countries have secretly sought centrifuges to make highly enriched uranium for nuclear weapons. In more recent times, several countries have secretly sought or built gas centrifuges in regions of tension. The main countries that have been of interest in the last two decades have been Pakistan, Iraq, Iran, and North Korea. Currently, most attention is focused on Iran, Pakistan, and North Korea. These states did not have the indigenous abilities to make gas centrifuges, focusing instead on illicit and questionable foreign procurement. The presentation covered the following main sections: Spread of centrifuges through illicit procurement; Role of export controls in stopping proliferation; Increasing the transparency of gas centrifuge programs in non-nuclear weapon states; and, Verified dismantlement of gas centrifuge programs. Gas centrifuges are important providers of low enriched uranium for civil nuclear power reactors. They also pose special nuclear proliferation risks. We all have special responsibilities to prevent the spread of gas centrifuges into regions of tension and to mitigate the consequences of their spread into the Middle East, South Asia, and North Asia.

  5. Laser and gas centrifuge enrichment

    NASA Astrophysics Data System (ADS)

    Heinonen, Olli

    2014-05-01

    Principles of uranium isotope enrichment using various laser and gas centrifuge techniques are briefly discussed. Examples on production of high enriched uranium are given. Concerns regarding the possibility of using low end technologies to produce weapons grade uranium are explained. Based on current assessments commercial enrichment services are able to cover the global needs of enriched uranium in the foreseeable future.

  6. Laser and gas centrifuge enrichment

    SciTech Connect

    Heinonen, Olli [Senior Fellow, Belfer Center for Science and International Affairs, Harvard Kennedy School, Cambridge, Massachusetts (United States)

    2014-05-09

    Principles of uranium isotope enrichment using various laser and gas centrifuge techniques are briefly discussed. Examples on production of high enriched uranium are given. Concerns regarding the possibility of using low end technologies to produce weapons grade uranium are explained. Based on current assessments commercial enrichment services are able to cover the global needs of enriched uranium in the foreseeable future.

  7. Modern gas centrifuge and rarefied-gas dynamics

    NASA Astrophysics Data System (ADS)

    Lowry, R. A.; Halle, E. V.; Wood, H. G., III

    1981-03-01

    The modern gas centrifuge appears to be the preferred method for the enrichment of the isotopes of uranium on a commercial scale. Centrifuge problems involving rarefield gas dynamics considerations are discussed.

  8. Separation of gas mixtures by centrifugation

    NASA Technical Reports Server (NTRS)

    Park, C.; Love, W. L.

    1972-01-01

    Magnetohydrodynamic (MHD) centrifuge utilizing electric currents and magnetic fields produces a magnetic force which develops supersonic rotational velocities in gas mixtures. Device is superior to ordinary centrifuges because rotation of gas mixture is produced by MHD force rather than mechanical means.

  9. Centrifugal device separates liquid from gas

    NASA Technical Reports Server (NTRS)

    Handlewich, R. M.; Stroup, K. E.

    1965-01-01

    Liquid-to-gas ratio is reduced from maximum efficiency of jet engine fuel by a centrifugal separator. The amount of liquid removed from the fuel is controlled by the separator-screen mesh size and its rotational speed.

  10. Enrichment of chromium isotopes by gas centrifugation

    NASA Astrophysics Data System (ADS)

    Szady, A. J.

    1989-10-01

    Recently, chromium isotopes have been enriched using gas centrifuges that were developed by the United States Department of Energy for the purpose of enriching uranium in the fissionable isotope 235U. The process gas employed was chromyl-fluoride. The enrichment was carried out using a single gas centrifuge that was set up to emphasize the enrichment of the light isotope 50Cr, which has a natural abundance of 4.35%. The highest enrichment tested to date is 21.4%. Higher values are possible with additional repasses. The heavy isotope 54Cr can be enriched instead of the 50Cr with an adjustment to the machine flows. Currently, work is under way to refine the cost projections associated with feed production and conversion back to an oxide and to optimize the centrifuge separative performance.

  11. Separative power of an optimised concurrent gas centrifuge

    E-print Network

    Bogovalov, S V

    2015-01-01

    The problem of separation of uranium isotopes in a concurrent gas centrifuge is solved analytically. Separative power of the optimized concurrent gas centrifuges equals to $\\delta U=12.7(V/700~{\\rm m/s})^2 (300 ~{\\rm K}/T)L, ~{\\rm kg ~SWU/yr}$, where $L$ and $V$ are the length and linear velocity of the rotor of the gas centrifuge, $T$ is the temperature. This formula well agrees with an empirical separative power of counter current gas centrifuges. The optimal value of the separative power is not unique on the plane $(p_w,v_z)$, where $p_w$ is pressure at the wall of the rotor and $v_z$ is axial velocity of the gas. This value is constant on a line defined by the equation $p_wv_z=constant$. Equations defining the mass flux and the electric power necessary to support the rotation of the gas centrifuge are obtained.

  12. Computation of flow and diffusion process in gas centrifuges

    NASA Astrophysics Data System (ADS)

    Merten, Alfons

    Numerical solutions of rotational symmetric behavior equations of flow and diffusion process in high speed gas centrifuges are presented. Numerical methods concern discretization of field equations, approximation of boundary conditions, consistency, and stability of differential equations. Time dependent rotational flows are examined for low, medium, and high Reynolds numbers. Application for flow and diffusion computation in gas centrifuges is developed.

  13. The American Gas Centrifuge Past, Present, and Future

    SciTech Connect

    Waters, Dean

    2004-09-15

    The art of gas centrifugation was born in 1935 at the University of Virginia when Dr. Jesse Beams demonstrated experimentally the separation of chlorine isotopes using an ultra-high speed centrifuge. Dr. Beam’s experiment initiated work that created a rich history of scientific and engineering accomplishment in the United States in the art of isotope separation and even large scale biological separation by centrifugation. The early history of the gas centrifuge development was captured in a lecture and documented by Dr. Jesse Beams in 1975. Much of Dr. Beams lecture material is used in this paper up to the year 1960. Following work by Dr. Gernot Zippe at the University of Virginia between 1958 and 1960, the US government embarked on a centrifuge development program that ultimately led to the start of construction of the Gas Centrifuge Enrichment Plant in Piketon Ohio in the late 1970’s. The government program was abandoned in 1985 after investing in the construction of two of six planned process buildings, a complete supply chain for process and centrifuge parts, and the successful manufacture and brief operation of an initial complement of production machines that would have met 15 percent of the planned capacity of the constructed process buildings. A declining market for enriched uranium, a glut of uranium enrichment capacity worldwide, and the promise of a new laser based separation process factored in the decision to stop the government program. By the late 1990’s it had become evident that gas centrifugation held the best promise to produce enriched uranium at low cost. In1999, the United States Enrichment Corporation undertook an initiative to revive the best of the American centrifuge technology that had been abandoned fourteen years earlier. This is an exciting story and one that when complete will enable the United States to maintain its domestic supply and to be highly competitive in the world market for this important energy commodity. (auth)

  14. The effect of gas fraction on centrifugal pump

    NASA Astrophysics Data System (ADS)

    Zhu, Z. T.; Wang, Y.; Zhao, L. F.; Ning, C.; Xie, S. F.; Liu, Z. C.

    2015-01-01

    In order to study the multiphase flow field in M125 centrifugal pump, three-dimensional modeling was used for internal flow through three-dimensional software Pro/E. Then based on SST turbulence model combining with Rayleigh-Plesset cavitation model, and structured grid to simulate the hydraulic characteristics of volute and impeller within different gas conditions. The velocity, pressure and gas volume fraction distributions of the interior flow field of volute and impeller were obtained and analyzed, which revealed the effect of gas fractions on the flow characteristic of the centrifugal pump.

  15. Review of the gas centrifuge until 1962. Part I: Principles of separation physics

    NASA Astrophysics Data System (ADS)

    Whitley, Stanley

    1984-01-01

    There are two sets of principles involved in the development of the gas centrifuge, the internal separation physics and the external means of spinning a rotor at very high speeds. Only the first aspect is discussed in this part of the review. First, the industrial requirement for the separation of the uranium isotopes is defined so that the separation history can be put in a modern perspective. The history of separation physics itself is then traced back to the theory of centrifugal force by Huygens and the equivalence of this force to that of gravity. The barometric equation giving the variation of atmospheric pressure with height and the law of partial pressures can then be adapted to the centrifuge to give the steady-state theory of separation. This work was completed in the last century but was not confirmed in its application to isotope separation until 1936. The detailed separation physics for non-steady-state conditions required for a production centrifuge was developed during the American wartime Manhattan Project. During this work the theory giving the maximum output of a centrifuge was developed by Dirac, and soon afterwards Cohen and Kaplan showed that the best method of operation for a production centrifuge is in a countercurrent mode of operation. This method gives a large separation factor at relatively small flow rates through the rotor. The theory of how to set up an internal countercurrent was given by Martin during an equivalent wartime German project, and refinements to the theory, showing how the countercurrent persists along a centrifuge rotor, was given by Dirac and Steenbeck, the latter during a postwar Russian project. This theory was extended by Parker, Ging, and Mayo of the University of Virginia, whose work was completed by 1962, the limit of this review.

  16. Direct Monte-Carlo simulations in a gas centrifuge

    NASA Astrophysics Data System (ADS)

    Roblin, Philippe; Doneddu, Frédéric

    2001-08-01

    The study is related to the centrifugation process for isotope separation. In a gas centrifuge, the major part of the rotating gas is modeled by fluid equations with this gas flow described by suitable Navier-Stokes. Nevertheless, a kinetic description of the gas is necessary for the feed gas expansion from the central pipe, and for the residual gas contained in the casing in which the cylinder rotates. For these rarefied regimes, we use Direct Monte-Carlo Simulations. In the first case, the simulations provide more realistic boundary conditions for fluid flow calculations. In the second case, we use DSMC to determine the mechanical power of the rotating cylinder and the heat flux dissipated on this cylinder and the fixed cylinder of the casing.

  17. Study of isotope separation of some chemical elements in a gas centrifuge

    NASA Astrophysics Data System (ADS)

    Aisen, E. M.; Borisevich, V. D.; Levin, E. V.; Popov, G. E.; Tikhomirov, A. V.; Yupatov, S. V.

    1996-02-01

    The procedure of the numerical technique adjustment on the selected type of the gas centrifuge is considered. A satisfactory agreement is shown between theoretical and experimental results for enrichment of sulfur or tellurium isotopes in a single gas centrifuge.

  18. Gas Centrifuge Enrichment Plant Safeguards System Modeling

    SciTech Connect

    Elayat, H A; O'Connell, W J; Boyer, B D

    2006-06-05

    The U.S. Department of Energy (DOE) is interested in developing tools and methods for potential U.S. use in designing and evaluating safeguards systems used in enrichment facilities. This research focuses on analyzing the effectiveness of the safeguards in protecting against the range of safeguards concerns for enrichment plants, including diversion of attractive material and unauthorized modes of use. We developed an Extend simulation model for a generic medium-sized centrifuge enrichment plant. We modeled the material flow in normal operation, plant operational upset modes, and selected diversion scenarios, for selected safeguards systems. Simulation modeling is used to analyze both authorized and unauthorized use of a plant and the flow of safeguards information. Simulation tracks the movement of materials and isotopes, identifies the signatures of unauthorized use, tracks the flow and compilation of safeguards data, and evaluates the effectiveness of the safeguards system in detecting misuse signatures. The simulation model developed could be of use to the International Atomic Energy Agency IAEA, enabling the IAEA to observe and draw conclusions that uranium enrichment facilities are being used only within authorized limits for peaceful uses of nuclear energy. It will evaluate improved approaches to nonproliferation concerns, facilitating deployment of enhanced and cost-effective safeguards systems for an important part of the nuclear power fuel cycle.

  19. Practical computation of multidimensional thermal flows in a gas centrifuge

    NASA Astrophysics Data System (ADS)

    Berger, M. H.

    1982-12-01

    A finite element theory for Onsager's two dimensional equation which approximates the steady, viscous, gas motion in a high speed centrifuge was derived. A new high order tensor product element is proposed to make the computations easy. The method of weighted residuals is used to construct the stiffness matrix, associated boundary integrals, and load vectors. It is shown that Ekman suction conditions along horizontal surfaces are natural boundary conditions of the weak approximation. A class of pure boundary value problems are solved for the field variables of interest. The effect of Ekman suction on the flow by computing with and without suction was evaluated. The case of pure two dimensional flow where the azimuthal velocity perturbation is presumed to vanish is evaluated. The effect of this simplifying assumption on the end to end temperature difference necessary for a given circulation is discussed. It is shown that the streamfunction must be graphed in physical coordinates for the isolines to be streamlines. Only in this form do the velocity vectors lie tangent to the contours and the radial velocity is redefined for graphical purposes.

  20. Modeling of UF6 enrichment with gas centrifuges for nuclear safeguards activities

    NASA Astrophysics Data System (ADS)

    Mercurio, G.; Peerani, P.; Richir, P.; Janssens, W.; Eklund, G.

    2012-09-01

    The physical modeling of uranium isotopes (235U, 238U) separation process by centrifugation of is a key aspect for predicting the nuclear fuel enrichment plant performances under surveillance by the Nuclear Safeguards Authorities. In this paper are illustrated some aspects of the modeling of fast centrifuges for UF6 gas enrichment and of a typical cascade enrichment plant with the Theoretical Centrifuge and Cascade Simulator (TCCS). The background theory for reproducing the flow field characteristics of a centrifuge is derived from the work of Cohen [1] where the separation parameters are calculated using the solution of a differential enrichment equation. In our case we chose to solve the hydrodynamic equations for the motion of a compressible fluid in a centrifugal field using the Berman - Olander vertical velocity radial distribution [2] and the solution was obtained using the Matlab software tool [3]. The importance of a correct estimation of the centrifuge separation parameters at different flow regimes, lies in the possibility to estimate in a reliable way the U enrichment plant performances, once the separation external parameters are set (feed flow rate and feed, product and tails assays)[4]. Using the separation parameters of a single centrifuge allow to determine the performances of an entire cascade and, for this purpose; the software Simulink [3] was used. The outputs of the calculation are the concentrations (assays) and the flow rates of the enriched (product) and depleted (tails) gas mixture. These models represent a valid additional tool, in order to verify the compliance of the U enrichment plant operator declarations with the "on site" inspectors' measurements.

  1. Modeling of UF{sub 6} enrichment with gas centrifuges for nuclear safeguards activities

    SciTech Connect

    Mercurio, G.; Peerani, P.; Richir, P.; Janssens, W.; Eklund, G. [European Commission, Joint Research Centre, Institute for Transuranium Elements Via Fermi, 2749-TP181,20127 Ispra (Italy)

    2012-09-26

    The physical modeling of uranium isotopes ({sup 235}U, {sup 238}U) separation process by centrifugation of is a key aspect for predicting the nuclear fuel enrichment plant performances under surveillance by the Nuclear Safeguards Authorities. In this paper are illustrated some aspects of the modeling of fast centrifuges for UF{sub 6} gas enrichment and of a typical cascade enrichment plant with the Theoretical Centrifuge and Cascade Simulator (TCCS). The background theory for reproducing the flow field characteristics of a centrifuge is derived from the work of Cohen where the separation parameters are calculated using the solution of a differential enrichment equation. In our case we chose to solve the hydrodynamic equations for the motion of a compressible fluid in a centrifugal field using the Berman - Olander vertical velocity radial distribution and the solution was obtained using the Matlab software tool. The importance of a correct estimation of the centrifuge separation parameters at different flow regimes, lies in the possibility to estimate in a reliable way the U enrichment plant performances, once the separation external parameters are set (feed flow rate and feed, product and tails assays). Using the separation parameters of a single centrifuge allow to determine the performances of an entire cascade and, for this purpose; the software Simulink was used. The outputs of the calculation are the concentrations (assays) and the flow rates of the enriched (product) and depleted (tails) gas mixture. These models represent a valid additional tool, in order to verify the compliance of the U enrichment plant operator declarations with the 'on site' inspectors' measurements.

  2. Design and operation of the world's highest pressure gas injection centrifugal compressors

    Microsoft Academic Search

    C. H. Jr. Geary; L. P. Damratowski; C. Seyer

    1976-01-01

    This study discusses the design features and operational case histories of high pressure, centrifugal gas-injection compressors. These compressors are currently being operated in the Phillips Group-Ekofisk, North Sea Project. High density gas compression can involve a problem called subsynchronous rotor whirl in centrifugal compressors. The methods of attacking and solving this problem are discussed. It is concluded that centrifugal compressors

  3. Numerical simulation of the countercurrent flow in a gas centrifuge

    NASA Astrophysics Data System (ADS)

    Cloutman, L. D.; Gentry, R. A.

    1983-03-01

    A finite difference method for the numerical simulation of the axisymmetric countercurrent flow in a gas centrifuge is presented. A time-marching technique is used to relay an arbitrary initial condition to the desired steady-state solution. All boundary layers can be resolved, and nonlinear effects may be included. Numerical examples are presented. It is concluded that this technique is capable of predicting accurately the performance of a wide variety of machines under all operating conditions of interest.

  4. Numerical simulation of the countercurrent flow in a gas centrifuge

    NASA Astrophysics Data System (ADS)

    Cloutman, L. D.; Gentry, R. A.

    A finite difference method is presented for the numerical simulation of the axisymmetric countercurrent flows in gas centrifuge. A time marching technique is used to relax an arbitrary initial condition to the desired steady state solution. All boundary layers may be resolved. It is concluded that this technique is capable of accurately predicting the performance of a wide variety of machines under all operating conditions of interest.

  5. Parallel centrifugal gas compressors can be controlled more effectively

    SciTech Connect

    Staroselsky, N.; Ladin, L.

    1986-11-03

    Energy efficiency of parallel, centrifugal gas compressors can be improved by controlling the compressors to unload simultaneously to their surge limits. Simultaneous unloading to the surge limits can also allow more precise pressure control, provide better compressor protection, and allow simpler automated control systems. Specific power consumption is also offered as an improved definition of energy efficiency. Because polytropic efficiency, the most common efficiency measure, defines only the energy efficiency to compress a gas between the inlet port and the discharge port of a compressor, it does not account for the efficiency of gas delivery to the user. Specific power consumption includes energy costs that must be paid for but which are not accounted for by polytropic efficiency. This first of two articles discusses the concept of simultaneous loading and unloading of centrifugal compressors and compares the method with other control strategies. The concept of specific power consumption is also defined. The conclusion describes an algorithm for simultaneous loading and unloading to the surge limit. The efficiency and reliability of centrifugal compressors can be severely limited by the control system. Less-than-effective controls, rather than mechanical design, is often the cause of lost efficiency, shutdowns, and damage.

  6. Aerodynamically induced radial forces in a centrifugal gas compressor. Part 1: Experimental measurement

    Microsoft Academic Search

    J. J. Moore; M. B. Flathers

    1998-01-01

    Net radial loading arising from asymmetric pressure fields in the volutes of centrifugal pumps during off-design operation is well known and has been studied extensively. In order to achieve a marked improvement in overall efficiency in centrifugal gas compressors, vaneless volute diffusers are matched to specific impellers to yield improved performance over a wide application envelope. As observed in centrifugal

  7. Remarks on the axial flow taper in a countercurrent gas centrifuge

    NASA Astrophysics Data System (ADS)

    Vonhalle, E.

    1983-06-01

    The effect of an axially varying countercurrent circulation rate in a gas centrifuge on the efficiency factors, e/sub I/ (the ideality efficiency) and e/sub C/ (the circulation efficiency), was investigated. The optimum value of the centrifuge parameter, m, which is a measure of the countercurrent circulation rate, is determined as a function of axial position in the centrifuge. Corresponding values of the centrifuge efficiency are presented.

  8. Separation of carbon dioxide and methane in continuous countercurrent gas centrifuges

    Microsoft Academic Search

    Ralph van Wissen; Michael Golombok; J. J. H. Brouwers

    2005-01-01

    The goal of this study is to determine the order of magnitude of the maximum achievable separation for decontaminating a natural gas well using a gas centrifuge. Previously established analytical approximations are not applicable for natural gas decontamination. Numerical simulations based on the batch case show that although the separative strength of the centrifuge is quite good, its throughput is

  9. 10 CFR Appendix B to Part 110 - Illustrative List of Gas Centrifuge Enrichment Plant Components Under NRC's Export Licensing...

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ...2014-01-01 false Illustrative List of Gas Centrifuge Enrichment Plant Components Under NRC's...Part 110—Illustrative List of Gas Centrifuge Enrichment Plant Components Under NRC's...especially designed or prepared for use in gas centrifuges. Note: The gas...

  10. 10 CFR Appendix B to Part 110 - Illustrative List of Gas Centrifuge Enrichment Plant Components Under NRC's Export Licensing...

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ...2013-01-01 false Illustrative List of Gas Centrifuge Enrichment Plant Components Under NRC's...Part 110—Illustrative List of Gas Centrifuge Enrichment Plant Components Under NRC's...especially designed or prepared for use in gas centrifuges. Note: The gas...

  11. 10 CFR Appendix B to Part 110 - Illustrative List of Gas Centrifuge Enrichment Plant Components Under NRC's Export Licensing...

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ...2011-01-01 false Illustrative List of Gas Centrifuge Enrichment Plant Components Under NRC's...Part 110—Illustrative List of Gas Centrifuge Enrichment Plant Components Under NRC's...especially designed or prepared for use in gas centrifuges. Note: The gas...

  12. 10 CFR Appendix B to Part 110 - Illustrative List of Gas Centrifuge Enrichment Plant Components Under NRC's Export Licensing...

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ...2010-01-01 false Illustrative List of Gas Centrifuge Enrichment Plant Components Under NRC's...Part 110—Illustrative List of Gas Centrifuge Enrichment Plant Components Under NRC's...especially designed or prepared for use in gas centrifuges. Note: The gas...

  13. 10 CFR Appendix B to Part 110 - Illustrative List of Gas Centrifuge Enrichment Plant Components Under NRC's Export Licensing...

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ...2012-01-01 false Illustrative List of Gas Centrifuge Enrichment Plant Components Under NRC's...Part 110—Illustrative List of Gas Centrifuge Enrichment Plant Components Under NRC's...especially designed or prepared for use in gas centrifuges. Note: The gas...

  14. New generation enrichment monitoring technology for gas centrifuge enrichment plants

    SciTech Connect

    Ianakiev, Kiril D [Los Alamos National Laboratory; Alexandrov, Boian S. [Los Alamos National Laboratory; Boyer, Brian D. [Los Alamos National Laboratory; Hill, Thomas R. [Los Alamos National Laboratory; Macarthur, Duncan W. [Los Alamos National Laboratory; Marks, Thomas [Los Alamos National Laboratory; Moss, Calvin E. [Los Alamos National Laboratory; Sheppard, Gregory A. [Los Alamos National Laboratory; Swinhoe, Martyn T. [Los Alamos National Laboratory

    2008-06-13

    The continuous enrichment monitor, developed and fielded in the 1990s by the International Atomic Energy Agency, provided a go-no-go capability to distinguish between UF{sub 6} containing low enriched (approximately 4% {sup 235}U) and highly enriched (above 20% {sup 235}U) uranium. This instrument used the 22-keV line from a {sup 109}Cd source as a transmission source to achieve a high sensitivity to the UF{sub 6} gas absorption. The 1.27-yr half-life required that the source be periodically replaced and the instrument recalibrated. The instrument's functionality and accuracy were limited by the fact that measured gas density and gas pressure were treated as confidential facility information. The modern safeguarding of a gas centrifuge enrichment plant producing low-enriched UF{sub 6} product aims toward a more quantitative flow and enrichment monitoring concept that sets new standards for accuracy stability, and confidence. An instrument must be accurate enough to detect the diversion of a significant quantity of material, have virtually zero false alarms, and protect the operator's proprietary process information. We discuss a new concept for advanced gas enrichment assay measurement technology. This design concept eliminates the need for the periodic replacement of a radioactive source as well as the need for maintenance by experts. Some initial experimental results will be presented.

  15. Centrifugal compression of soft particle packings: Theory and experiment K. N. Nordstrom,1

    E-print Network

    Gollub, Jerry P.

    Centrifugal compression of soft particle packings: Theory and experiment K. N. Nordstrom,1 E to centrifugal compression, for arbitrary constitutive relation between stress and strain. Example solutions by centrifugal compression, and we illustrate our method with experiments on 1 m diam- eter NIPA microgel beads

  16. Simulation of countercurrent flow in a gas centrifuge

    NASA Astrophysics Data System (ADS)

    Greenspan, H. P.

    1982-04-01

    Certain effects of geometry and configuration on the circulation patterns in a gas centrifuge can be readily explored and tested in a liquid simulator. Since the most interesting situations involve countercurrent flows, the simulator must be one in which such motion is both easy to produce and accessible for experimentation. An apparatus that seems to meet these requirements is a partially filled rotating cylinder, which has one endplate that rotates with a slightly different angular velocity. The device, shown schematically can be modified to produce source-sink or mass driven flows as well. The rotation rates, fluid volume fraction (i.e., the thickness of the fluid layer) and the fluid rheology are the main control factors to be set in any experiment.

  17. Systems approach used in the Gas Centrifuge Enrichment Plant

    SciTech Connect

    Rooks, W.A. Jr.

    1982-01-01

    A requirement exists for effective and efficient transfer of technical knowledge from the design engineering team to the production work force. Performance-Based Training (PBT) is a systematic approach to the design, development, and implementation of technical training. This approach has been successfully used by the US Armed Forces, industry, and other organizations. The advantages of the PBT approach are: cost-effectiveness (lowest life-cycle training cost), learning effectiveness, reduced implementation time, and ease of administration. The PBT process comprises five distinctive and rigorous phases: Analysis of Job Performance, Design of Instructional Strategy, Development of Training Materials and Instructional Media, Validation of Materials and Media, and Implementation of the Instructional Program. Examples from the Gas Centrifuge Enrichment Plant (GCEP) are used to illustrate the application of PBT.

  18. Computing experiments for study of cadmium isotope separation by gas centrifuges

    NASA Astrophysics Data System (ADS)

    Aisen, E. M.; Borisevich, V. D.; Potapov, D. V.; Rudnev, A. I.; Sulaberidze, G. A.; Tikhomirov, A. V.

    The basic regularities for enrichment of the 116Cd isotope in the form of cadmium dimethyl in a single gas centrifuge and a square cascade of gas centrifuges have been studied by means of numerical simulation techniques. In these computing experiments it has been found the influence of a loss of the process gas due to its partial decomposition to enrichment of the desired isotope.

  19. Analysis of gas centrifuge cascade for separation of multicomponent isotopes and optimal feed position

    SciTech Connect

    Chuntong Ying; Hongjiang Wu; Mingsheng Zhou; Yuguang Nie; Guangjun Liu [Tsinghua Univ., Beijing (China)

    1997-10-01

    Analysis of the concentration distribution in a gas centrifuge cascade for separation of multicomponent isotope mixtures is different from that in a cascade for separation of two-component mixtures. This paper presents the governing equations for a multicomponent isotope separation cascade. Numerically predicted separation factors for the gas centrifuge cascade agree well with the experimental data. A theoretical optimal feed position is derived for a short square cascade for a two-component mixture in a close-separation case. The optimal feed position for a gas centrifuge cascade for separation of multicomponent mixture is discussed.

  20. Development and field test results of an efficient downhole centrifugal gas separator

    SciTech Connect

    Kobylinski, L.S.; Brienen; Taylor, F.T.

    1983-03-01

    Performance degradation of a centrifugal pump due to ingested free gas is well understood. High GOR wells typically have a very high free gas to liquid ratio at the pump intake making the efficiency of the downhole gas separator crucially important in preventing free gas from entering the pump and hence producing the well successfully. This paper describes the design, development and laboratory testing of a new rotary gas separator which is currently being installed in high GOR wells. Laboratory tests were conducted using air in water at low intake pressures. Free gas and liquid separation theory is briefly reviewed to show that test conditions in many respects represent a worst case downhole condition from which valid predictions of downhole performance can be made. Actual oil and gas production rate data from several oil wells showing before and after performance of the rotary design and conventional reverse flow designs are also presented. An average improvement in production of 95% was observed. Comparisons of free gas separation efficiency at pump intake conditions of pressure, temperature and viscosity are also made.

  1. New Measures to Safeguard Gas Centrifuge Enrichment Plants

    SciTech Connect

    Whitaker, Jr., James [ORNL; Garner, James R [ORNL; Whitaker, Michael [ORNL; Lockwood, Dunbar [U.S. Department of Energy, NNSA; Gilligan, Kimberly V [ORNL; Younkin, James R [ORNL; Hooper, David A [ORNL; Henkel, James J [ORNL; Krichinsky, Alan M [ORNL

    2011-01-01

    As Gas Centrifuge Enrichment Plants (GCEPs) increase in separative work unit (SWU) capacity, the current International Atomic Energy Agency (IAEA) model safeguards approach needs to be strengthened. New measures to increase the effectiveness of the safeguards approach are being investigated that will be mutually beneficial to the facility operators and the IAEA. One of the key concepts being studied for application at future GCEPs is embracing joint use equipment for process monitoring of load cells at feed and withdrawal (F/W) stations. A mock F/W system was built at Oak Ridge National Laboratory (ORNL) to generate and collect F/W data from an analogous system. The ORNL system has been used to collect data representing several realistic normal process and off-normal (including diversion) scenarios. Emphasis is placed on the novelty of the analysis of data from the sensors as well as the ability to build information out of raw data, which facilitates a more effective and efficient verification process. This paper will provide a progress report on recent accomplishments and next steps.

  2. Numerical study of the effects of curvature on the fluid dynamics of gas centrifuges

    NASA Astrophysics Data System (ADS)

    Jordan, J. A.; Gunzburger, M. D.; Wood, H. G., III

    1983-06-01

    A finite element method for the approximate solution of the flow in rapidly rotating gas centrifuges is presented. The Onsager model, as amended by Maslen, is used to derive the model equations to be discretized. The pancake effects are not assumed in the model. The hydrodynamics of a gas centrifuge, numerical examples done with and without these curvature terms are presented. Two flow models are used, one for flow driven by a linear temperature gradient along the wall and the other for flow driven by axial mass fluxes through the end caps of the centrifuge.

  3. Defining the needs for gas centrifuge enrichment plants advanced safeguards

    SciTech Connect

    Boyer, Brian David [Los Alamos National Laboratory; Erpenbeck, Heather H [Los Alamos National Laboratory; Miller, Karen A [Los Alamos National Laboratory; Swinhoe, Martyn T [Los Alamos National Laboratory; Ianakiev, Kiril [Los Alamos National Laboratory; Marlow, Johnna B [Los Alamos National Laboratory

    2010-04-05

    Current safeguards approaches used by the International Atomic Energy Agency (IAEA) at gas centrifuge enrichment plants (GCEPs) need enhancement in order to verify declared low-enriched (LEU) production, detect undeclared LEU production and detect highly enriched uranium (HEU) production with adequate detection probability using nondestructive assay (NDA) techniques. At present inspectors use attended systems, systems needing the presence of an inspector for operation, during inspections to verify the mass and {sup 235}U enrichment of declared UF{sub 6} containers used in the process of enrichment at GCEPs. In verifying declared LEU production, the inspectors also take samples for off-site destructive assay (DA) which provide accurate data, with 0.1% to 0.5% measurement uncertainty, on the enrichment of the UF{sub 6} feed, tails, and product. However, taking samples of UF{sub 6} for off-site analysis is a much more labor and resource intensive exercise for the operator and inspector. Furthermore, the operator must ship the samples off-site to the IAEA laboratory which delays the timeliness of results and interruptions to the continuity of knowledge (CofK) of the samples during their storage and transit. This paper contains an analysis of possible improvements in unattended and attended NDA systems such as process monitoring and possible on-site analysis of DA samples that could reduce the uncertainty of the inspector's measurements and provide more effective and efficient IAEA GCEPs safeguards. We also introduce examples advanced safeguards systems that could be assembled for unattended operation.

  4. The effect of source-sink geometry on enrichment in a gas centrifuge

    NASA Astrophysics Data System (ADS)

    Conlisk, A. T.

    1983-10-01

    Solutions to the mass transfer problem in a gas centrifuge are examined as a function of source-sink geometry. The model centrifuge consists of a pair of concentric circular cylinders bounded on the top and bottom by horizontal end plates; the apparatus rotates rapidly about the axis of the cylinders. During steady operation, a binary gas mixture containing species A and B is injected into the container through small axisymmetric slots located on the sidewalls. Solutions for the concentration field within the centrifuge are obtained for mechanically or thermally driven centrifuges; maximum values of the separation factor based on product and feed mass fractions are predicted as a function of feed, product, and waste port locations. Both moderate and strongly forced flows in the container are considered.

  5. Numerical simulation of bellows effect on flow and separation of uranium isotopes in a supercritical gas centrifuge

    NASA Astrophysics Data System (ADS)

    Borisevich, V. D.; Morozov, O. E.; Godisov, O. N.

    2000-12-01

    Numerical solving of the Navier-Stokes and convection-diffusion equations by the finite difference technique has been applied to study the influence of bellows on the flow and separation of uranium isotopes in a single supercritical gas centrifuge. Dependence of the separative power of a gas centrifuge on geometric parameters and position of a bellows on a rotor wall as well as the effect of scoop drag and feed flow on isotope separation in a gas centrifuge with a bellows have been obtained in computing experiments. It was demonstrated that increase of the separative power with increase of the gas centrifuge length is less considerable than predicted by the Dirac's law.

  6. On the enrichment of low-abundant isotopes of light chemical elements by gas centrifuges

    NASA Astrophysics Data System (ADS)

    Borisevich, V. D.; Morozov, O. E.; Zaozerskiy, Yu. P.; Shmelev, G. M.; Shipilov, Yu. D.

    2000-08-01

    A brief review of the main areas for the application of the isotopes 15N and 13C is made. Separation of the nitrogen isotopes in a single gas centrifuge in the form of pure nitrogen, ammonia, and trifluoride of nitrogen as well as the carbon isotopes in the form of carbon dioxide has been studied by means of numerical simulation. The parameters of the centrifugal machine investigated were close to the parameters of the Iguassu machine. The dependence of the efficiency criterion versus the basic parameters of the separation process has been explored in the computational experiments. Comparisons of the calculated results with the experimental data have shown good agreement. The results obtained have demonstrated the possibility of using gas centrifuge technology to enrich successfully the low-abundant isotopes of light chemical elements.

  7. Application of systems engineering techniques (reliability, availability, maintainability, and dollars) to the Gas Centrifuge Enrichment Plant

    Microsoft Academic Search

    J. G. Boylan; R. C. DeLozier

    1982-01-01

    The systems engineering function for the Gas Centrifuge Enrichment Plant (GCEP) covers system requirements definition, analyses, verification, technical reviews, and other system efforts necessary to assure good balance of performance, safety, cost, and scheduling. The systems engineering function will support the design, installation, start-up, and operational phases of GCEP. The principal objectives of the systems engineering function are to: assure

  8. Low loss liquid helium transfer system, using a high performance centrifugal pump and cold gas exchange

    Microsoft Academic Search

    H. Berndt; R. Doll; U. Jahn; W. Wiedemann

    1988-01-01

    A liquid-He transfer system with overall transfer losses of less than 2 percent is proposed. In comparison with a conventional transfer system, the design achieves energy and running time savings for He-liquefaction of up to 30 percent. The system consists of a reliable completely magnetic suspended centrifugal pump, submerged in the liquid, and a double transfer line allowing cold gas

  9. Enrichment of tellurium isotopes for pure 123I production using gas ultra-centrifuges

    NASA Astrophysics Data System (ADS)

    Suvorov, I. A.; Tcheltsov, A. N.

    1993-09-01

    Enrichment of 123Te has been carried out in a laboratory-type rectangular cascade of gas centrifuges where the separation of gaseous TeF 6 took place. As a result extremely highly enriched 123Te was produced in gram quantities.

  10. Numerical methods for solving some fluid mechanics problems met in a strongly rotating gas centrifuge

    NASA Astrophysics Data System (ADS)

    La Hargue, Jp.; Baramayer, Soub

    The communication is presented in the form of a computer-animation movie, made from the output data of three numerical models. These models have been built to investigate in a gas centrifuge respectively the flow, the species separation and the optimization of the flow field. The figures heredown have been extracted from the movie.

  11. Laser-Based Data Acquisition In Gas Centrifuge Environments Using Optical Fibers

    NASA Astrophysics Data System (ADS)

    Cates, M. R.; Allison, S. W.; Marshall, B.; Davies, T. J.; Franks, L. A.; Nelson, M. A.; Noel, B. W.

    1984-10-01

    The operating environment of gas centrifuges poses three basic experimental problems: rotating reference frame, corrosive effects of UF6 gas, and vacuum coupling. Diagnostic experiments in this environment effectively use fiber optics as laser transport systems and data extraction channels. Access to the interior of rotating centrifuges is only from a central nonrotating column assembly. Optical paths are often long and difficult to measure in static conditions with precision necessary in operating conditions. Residual traces of HF gas, from UF6, damage exposed optical components over time. Diagnostic measurements requiring pulsed laser sources and analysis of fluorescence emissions, both from UF6 gas and from temperature-sensitive phosphor are described, with emphasis on optical fiber components and experimental design configurations. The studies were done at Oak Ridge Gaseous Diffusion Plant through the Centrifuge Physics Department of the Centrifuge Division. The advantages of fiber optics methods include: optical path flexibility, small and adaptable size of components, utility in connection with moveable assemblies, and relative ease of vacuum isolation.

  12. Realities of verifying the absence of highly enriched uranium (HEU) in gas centrifuge enrichment plants

    Microsoft Academic Search

    1990-01-01

    Over a two and one-half year period beginning in 1981, representatives of six countries (United States, United Kingdom, Federal Republic of Germany, Australia, The Netherlands, and Japan) and the inspectorate organizations of the International Atomic Energy Agency and EURATOM developed and agreed to a technically sound approach for verifying the absence of highly enriched uranium (HEU) in gas centrifuge enrichment

  13. Numerical simulation of countercurrent flow and diffusion processes in a separating gas centrifuge

    NASA Astrophysics Data System (ADS)

    Kozlov, S. A.; Eriklintsev, I. V.

    2013-07-01

    We present a linear model for the numerical simulation of antisymmetric countercurrent flow in a gas centrifuge which has high computation speeds. A model describing the mechanics and thermodynamics of a gas is proposed with an equation for the concentration of separated components. Numerical examples are presented. We conclude that this technique is capable of accurately predicting the performance of a wide variety of machines under all operating conditions of interest.

  14. Experience in full-load testing of natural gas centrifugal compressors for rotordynamics improvements

    Microsoft Academic Search

    A. Gelin; J.-M. Pugnet; D. Bolusset; P. Friez

    1997-01-01

    During full-load shop tests under natural gas, two multistage centrifugal compressors exhibited subsynchronous vibrations. Both of them are low-flow, high-pressure, high rotational speed compressors, and are fitted with tilting and bearings and dry gas seals. A rotating stall problem was first eliminated by a modification of the diffuser geometry. Then, aerodynamic excitations caused the rotors to operate at their stability

  15. CFD Simulation of 3D Flow field in a Gas Centrifuge

    SciTech Connect

    Dongjun Jiang; Shi Zeng [Tsinghua University, Beijing, 100084 (China)

    2006-07-01

    A CFD method was used to study the whole flow field in a gas centrifuge. In this paper, the VSM (Vector Splitting Method) of the FVM (Finite Volume Method) was used to solve the 3D Navier-Stokes equations. An implicit second-order upwind scheme was adopted. The numerical simulation was successfully performed on a parallel cluster computer and a convergence result was obtained. The simulation shows that: in the withdrawal chamber, a strong detached shock wave is formed in front of the scoop; as the radial position increases, the shock becomes stronger and the distance to scoop front surface is smaller. An oblique shock forms in the clearance between the scoop and the centrifuge wall; behind the shock-wave, the radially-inward motion of gas is induced because of the imbalance of the pressure gradient and the centrifugal force. In the separation chamber, a countercurrent is introduced. This indicates that CFD method can be used to study the complex three-dimensional flow field of gas centrifuges. (authors)

  16. Aerosol characterization with centrifugal aerosol spectrometers: Theory and experiment

    SciTech Connect

    Johnson, D.L.; Martonen, T.B.

    1989-01-01

    A general mathematical model describing the motion of particles in aerosol centrifuges has been developed. It has been validated by comparisons of theoretically predicted calibration sites with experimental data from tests sizing aerosols in instruments of three different spiral duct configurations. By accurately simulating factors which influence centrifuge performance, the model enhances the versatility of existing instruments and promotes CAD (computer aided design) and CAM (computer aided manufacture) of new units. The model will permit more accurate aerodynamic classifications of airborne particles. Therefore, more precise determinations of deposition sites of inhaled aerosols within the lung will be possible, since such locations are primarily functions on the dynamic characteristics of motion. U.S. EPA risk assessment protocols of pollutant aerosols will thereby be improved.

  17. Theory on Measuring Orientation with MEMS Accelerometers in a Centrifuge

    E-print Network

    Beemer, Ryan D.; Murali, Madhuri; Biscontin, Giovanna; Aubeny, Charles

    2015-03-21

    fundamental part of the Internet of Things, a driving force behind Big Data, and the reason personal monitoring devices award us for using the stairs. MEMS sensors are even now becoming an essential tool for civil and geotechnical Page 1 engineers. A quick... there are a number of items to Page 8 consider: MEMS accelerometers can be used to measure vibrations and orientation, centrifuge gravity varies relative to the model coordinate, translation or rotation at large eccentricities can impact measurements, cross...

  18. Specialized centrifugal compressors for natural gas injection at 9200 psig

    Microsoft Academic Search

    1973-01-01

    A schematic drawing of the Ekofisk Phillips Norway Group plant shows the various steps to gas reinjection. The first commercial crude oil is being produced from this newly discovered giant North Sea oil field. During the second half of 1973, a complete gas separation plant and a reinjection plant will be placed in operation making it possible to recover all

  19. Verification of software codes for simulation of unsteady flows in a gas centrifuge

    NASA Astrophysics Data System (ADS)

    Abramov, V. A.; Bogovalov, S. V.; Borisevich, V. D.; Borman, V. D.; Kislov, V. A.; Tronin, I. V.; Tronin, V. N.; Yupatov, S. V.

    2013-06-01

    A simple semi-analytical solution is proposed for the problem of an unsteady gas flow in a gas centrifuge. The circulation in the centrifuge is driven by a source/sink of energy and by an external force (deceleration/acceleration of the gas rotation) acting on the gas at a given frequency. In the semi-analytical solution, the rotor is infinite, while the given forces vary harmonically with a given wave-length along the axial coordinate. As a result, the unsteady flow problem is reduced to a system of ordinary differential equations, which can be quickly solved to any prescribed accuracy. This problem is proposed for verifying numerical codes designed for the simulation of unsteady processes in gas centrifuges. A similar unsteady problem is solved numerically, in which case the cylinder is finite with the rotor length equal to the wavelength of the external force along the axis of rotation. The periodicity of the solution is set at end faces of the cylinder. As an example, the semi-analytical solution is compared with the numerical one obtained with these boundary conditions. The comparison confirms that the problem formulations are equivalent in both cases.

  20. Centrifugal compression of soft particle packings - theory and experiment

    E-print Network

    K. N. Nordstrom; E. Verneuil; W. G. Ellenbroek; T. C. Lubensky; J. P. Gollub; D. J. Durian

    2010-09-15

    An exact method is developed for computing the height of an elastic medium subjected to centrifugal compression, for arbitrary constitutive relation between stress and strain. Example solutions are obtained for power-law media and for cases where the stress diverges at a critical strain -- for example as required by packings composed of deformable but incompressible particles. Experimental data are presented for the centrifugal compression of thermo-responsive N-isopropylacrylamide (NIPA) microgel beads in water. For small radial acceleration, the results are consistent with Hertzian elasticity, and are analyzed in terms of the Young elastic modulus of the bead material. For large radial acceleration, the sample compression asymptotes to a value corresponding to a space-filling particle volume fraction of unity. Therefore we conclude that the gel beads are incompressible, and deform without deswelling. In addition, we find that the Young elastic modulus of the particulate gel material scales with cross-link density raised to the power 3.3+-0.8, somewhat larger than the Flory expectation.

  1. Design and prototyping of micro centrifugal compressor for ultra micro gas turbine

    Microsoft Academic Search

    Shimpei Mizuki; Toshiyuki Hirano; Yoshiyuki Koizumi; Gaku Minorikawa; Hoshio Tsujita; Mitsuo Iwahara; Ronglei Gu; Yutaka Ohta; Eisuke Outa

    2005-01-01

    In order to establish the design methodology of an ultra micro centrifugal compressor, which is the most important component\\u000a of an ultra micro gas turbine unit, a 10 times size of the final target compressor (impeller outer diameter 40 mm, corrected\\u000a rotational speed 220,000 r\\/min) was designed. The problems to be solved for downsizing were examined and a 2-dimensional impeller

  2. Review of the gas centrifuge until 1962. Part II: Principles of high-speed rotation

    NASA Astrophysics Data System (ADS)

    Whitley, Stanley

    1984-01-01

    The principles of the separation physics of the gas centrifuge were described in Part I of this review. In this second section the principles involved in spinning the rotors of these centrifuges are described. Three types of rotor can be identified, depending on the ratio of length to diameter. If the rotor is very short, length-diameter ratio less than one, it is gyroscopically stable and easy to spin. If the length-diameter ratio is in the region of 4 or 5, the rotor behaves as a rigid body and is relatively easy to accelerate to speed; however, it has a tendency at full speed to exhibit gyroscopic precessions. Finally, if the length-diameter ratio is very large, the rotor becomes easy to stabilize gyroscopically, but it is difficult to get it to speed because long rotors are very flexible and have resonant frequencies of flexure lower than the operating speed. The problems of these three types of centrifuge (the rotor dynamics, the bearings used to support the rotor, and the stress analysis of the rotating components) were investigated in the last century as part of classical mechanics because of the emergence of steam turbines during the latter part of the industrial revolution. These early principles are briefly reviewed, with particular reference to the work of De Laval, who invented the principle of self-balancing, Reynolds and Evershed, who developed hydrodynamic and magnetic bearing, respectively, and Chree, who did the most extensive early work on the stress analysis of tubes and discs. The work is described as it applies to the centrifuges developed in America and Germany during the war and in the Soviet Union after the war. The work of Beams in America is described in most detail, since he and his colleagues developed all three types of centrifuge during the Manhattan Project. The other work described is that of Groth and Beyerle, who developed subcritical machines in Germany during the war, and of Steenbeck and Zippe, who helped to develop both subcritical and supercritical centrifuges in the Soviet Union after the war. Little of this latter work has been published, but Zippe redeveloped the subcritical machine at the University of Virginia. The description of this machine concludes the present review.

  3. Aerodynamically induced radial forces in a centrifugal gas compressor. Part 1: Experimental measurement

    SciTech Connect

    Moore, J.J.; Flathers, M.B. [Solar Turbines Inc., San Diego, CA (United States)

    1998-04-01

    Net radial loading arising from asymmetric pressure fields in the volutes of centrifugal pumps during off-design operation is well known and has been studied extensively. In order to achieve a marked improvement in overall efficiency in centrifugal gas compressors, vaneless volute diffusers are matched to specific impellers to yield improved performance over a wide application envelope. As observed in centrifugal pumps, nonuniform pressure distributions that develop during operation above and below the design flow create static radial loads on the rotor. In order to characterize these radial forces, a novel experimental measurement and post-processing technique is employed that yields both the magnitude and direction of the load by measuring the shaft centerline locus in the tilt-pad bearings. The method is applicable to any turbomachinery operating on fluid film radial bearings equipped with proximity probes. The forces are found to be a maximum near surge and increase with higher pressures and speeds. The results are nondimensionalized, allowing the radial loading for different operating conditions to be predicted.

  4. Separative power of plasma centrifuges

    NASA Astrophysics Data System (ADS)

    Simpson, S. W.

    1981-10-01

    A three-fluid model of rotating plasmas is used to predict the efficiency of plasma centrifuges. It is found that partially ionized plasma centrifuges of the type investigated cannot match the separative power of gas centrifuges for uranium enrichment.

  5. Low loss liquid helium transfer system, using a high performance centrifugal pump and cold gas exchange

    NASA Astrophysics Data System (ADS)

    Berndt, H.; Doll, R.; Jahn, U.; Wiedemann, W.

    A liquid-He transfer system with overall transfer losses of less than 2 percent is proposed. In comparison with a conventional transfer system, the design achieves energy and running time savings for He-liquefaction of up to 30 percent. The system consists of a reliable completely magnetic suspended centrifugal pump, submerged in the liquid, and a double transfer line allowing cold gas exchange between the transport vessel and the storage tank. The high-reliability maintenance-free operation, high total performance, and pure one-phase liquid flow make the present design suitable for transferring liquid He II in space applications.

  6. A finite volume scheme for calculating the interior flow in a gas centrifuge

    NASA Astrophysics Data System (ADS)

    Kirkpatrick, J. R.

    1986-12-01

    A numerical algorithm which is designed to calculate the flow patterns in a gas centrifuge is presented. The nodal equations are derived using finite volume concepts, thus ensuring rigorous conservation of mass, momentum, and energy for the computational cells and for the entire rotor. The method for solving the systems of nodal equations is designed to produce a steady-state solution using a mixture of time-dependent and time-independent equations. Streamlines for a sample configuration are shown. Comparison with results published by other authors shows good agreement.

  7. Raising gas-dynamic stability margin of axial and centrifugal compressor stages by means of vaned diffuser boundary layer control

    Microsoft Academic Search

    Ivan Lastivka

    2011-01-01

    Generalised research results that consider the upgradability of axial and centrifugal gas turbine engine compressors by means of gas-dynamic boundary layer control on bladed disks are demonstrated. Active and passive methods are used. Comparative analysis of the results has been carried out. The analysis is purposed to determine the influence of the flow circulation around the aerofoils on the performance

  8. RADIO FREQUENCY IDENTIFICATION DEVICES: EFFECTIVENESS IN IMPROVING SAFEGUARDS AT GAS-CENTRIFUGE URANIUM-ENRICHMENT PLANTS.

    SciTech Connect

    JOE,J.

    2007-07-08

    Recent advances in radio frequency identification devices (RFIDs) have engendered a growing interest among international safeguards experts. Potentially, RFIDs could reduce inspection work, viz. the number of inspections, number of samples, and duration of the visits, and thus improve the efficiency and effectiveness of international safeguards. This study systematically examined the applications of RFIDs for IAEA safeguards at large gas-centrifuge enrichment plants (GCEPs). These analyses are expected to help identify the requirements and desirable properties for RFIDs, to provide insights into which vulnerabilities matter most, and help formulate the required assurance tests. This work, specifically assesses the application of RFIDs for the ''Option 4'' safeguards approach, proposed by Bruce Moran, U. S. Nuclear Regulatory Commission (NRC), for large gas-centrifuge uranium-enrichment plants. The features of ''Option 4'' safeguards include placing RFIDs on all feed, product and tails (F/P/T) cylinders, along with WID readers in all FP/T stations and accountability scales. Other features of Moran's ''Option 4'' are Mailbox declarations, monitoring of load-cell-based weighing systems at the F/P/T stations and accountability scales, and continuous enrichment monitors. Relevant diversion paths were explored to evaluate how RFIDs improve the efficiency and effectiveness of safeguards. Additionally, the analysis addresses the use of RFIDs in conjunction with video monitoring and neutron detectors in a perimeter-monitoring approach to show that RFIDs can help to detect unidentified cylinders.

  9. Design and prototyping of micro centrifugal compressor for ultra micro gas turbine

    NASA Astrophysics Data System (ADS)

    Mizuki, Shimpei; Hirano, Toshiyuki; Koizumi, Yoshiyuki; Minorikawa, Gaku; Tsujita, Hoshio; Iwahara, Mitsuo; Gu, Ronglei; Ohta, Yutaka; Outa, Eisuke

    2005-12-01

    In order to establish the design methodology of an ultra micro centrifugal compressor, which is the most important component of an ultra micro gas turbine unit, a 10 times size of the final target compressor (impeller outer diameter 40 mm, corrected rotational speed 220,000 r/min) was designed. The problems to be solved for downsizing were examined and a 2-dimensional impeller was chosen as the first model due to its productivity. The conventional 1D prediction method and CFD were used. The prototyped compressor was tested by using cold air at the reduced speed of 110,000 r/min. Following to the 10 times model, a 5 times size of the final target model having fully 3-dimensional shape (impeller outer diameter 20mm, corrected rotational speed 500,000 r/min) was designed and tested by using hot gas at the reduced speed of 250,000 r/min.

  10. Boundary layers in centrifugal compressors. [application of boundary layer theory to compressor design

    NASA Technical Reports Server (NTRS)

    Dean, R. C., Jr.

    1974-01-01

    The utility of boundary-layer theory in the design of centrifugal compressors is demonstrated. Boundary-layer development in the diffuser entry region is shown to be important to stage efficiency. The result of an earnest attempt to analyze this boundary layer with the best tools available is displayed. Acceptable prediction accuracy was not achieved. The inaccuracy of boundary-layer analysis in this case would result in stage efficiency prediction as much as four points low. Fluid dynamic reasons for analysis failure are discussed with support from flow data. Empirical correlations used today to circumnavigate the weakness of the theory are illustrated.

  11. Calculation of UF sub 6 gas density, temperature, pressure, and Mach number changes across a normal shock in a gas-centrifuge environment

    NASA Astrophysics Data System (ADS)

    Gentry, R. A.

    1983-03-01

    The nonlinear Rankine-Hugoniot equations are solved to obtain changes in UF6 gas density, temperature, pressure, and Mach number across a normal shock in a gas centrifuge environment. Effects of the nonlinear temperature variation of the enthalpy and specific heats of UF6 are included to insure that realistic predictions of gas temperature and pressure are obtained. Tables of values of gas density, temperature, pressure, and Mach number describing conditions behind a normal shock are presented as functions of the upstream Mach number and the upstream gas temperature. Values of the gas stagnation temperature and stagnation pressure are also included. The tables give tabular results corresponding to centrifuge wall speeds ranging from 350 m/s to 1100 m/s.

  12. A Finite-Difference Numerical Method for Onsager's Pancake Approximation for Fluid Flow in a Gas Centrifuge

    SciTech Connect

    de Stadler, M; Chand, K

    2007-11-12

    Gas centrifuges exhibit very complex flows. Within the centrifuge there is a rarefied region, a transition region, and a region with an extreme density gradient. The flow moves at hypersonic speeds and shock waves are present. However, the flow is subsonic in the axisymmetric plane. The analysis may be simplified by treating the flow as a perturbation of wheel flow. Wheel flow implies that the fluid is moving as a solid body. With the very large pressure gradient, the majority of the fluid is located very close to the rotor wall and moves at an azimuthal velocity proportional to its distance from the rotor wall; there is no slipping in the azimuthal plane. The fluid can be modeled as incompressible and subsonic in the axisymmetric plane. By treating the centrifuge as long, end effects can be appropriately modeled without performing a detailed boundary layer analysis. Onsager's pancake approximation is used to construct a simulation to model fluid flow in a gas centrifuge. The governing 6th order partial differential equation is broken down into an equivalent coupled system of three equations and then solved numerically. In addition to a discussion on the baseline solution, known problems and future work possibilities are presented.

  13. Aerodynamically induced radial forces in a centrifugal gas compressor: Part 2 -- Computational investigation

    SciTech Connect

    Flathers, M.B.; Bache, G.E.

    1999-10-01

    Radial loads and direction of a centrifugal gas compressor containing a high specific speed mixed flow impeller and a single tongue volute were determined both experimentally and computationally at both design and off-design conditions. The experimental methodology was developed in conjunction with a traditional ASME PTC-10 closed-loop test to determine radial load and direction. The experimental study is detailed in Part 1 of this paper (Moore and Flathers, 1998). The computational method employs a commercially available, fully three-dimensional viscous code to analyze the impeller and the volute interaction. An uncoupled scheme was initially used where the impeller and volute were analyzed as separate models using a common vaneless diffuser geometry. The two calculations were then repeated until the boundary conditions at a chosen location in the common vaneless diffuser were nearly the same. Subsequently, a coupled scheme was used where the entire stage geometry was analyzed in one calculation, thus eliminating the need for manual iteration of the two independent calculations. In addition to radial load and direction information, this computational procedure also provided aerodynamic stage performance. The effect of impeller front face and rear face cavities was also quantified. The paper will discuss computational procedures, including grid generation and boundary conditions, as well as comparisons of the various computational schemes to experiment. The results of this study will show the limitations and benefits of Computational Fluid Dynamics (CFD) for determination of radial load, direction, and aerodynamic stage performance.

  14. A Monte Carlo Analysis of Gas Centrifuge Enrichment Plant Process Load Cell Data

    SciTech Connect

    Garner, James R [ORNL; Whitaker, J Michael [ORNL

    2013-01-01

    As uranium enrichment plants increase in number, capacity, and types of separative technology deployed (e.g., gas centrifuge, laser, etc.), more automated safeguards measures are needed to enable the IAEA to maintain safeguards effectiveness in a fiscally constrained environment. Monitoring load cell data can significantly increase the IAEA s ability to efficiently achieve the fundamental safeguards objective of confirming operations as declared (i.e., no undeclared activities), but care must be taken to fully protect the operator s proprietary and classified information related to operations. Staff at ORNL, LANL, JRC/ISPRA, and University of Glasgow are investigating monitoring the process load cells at feed and withdrawal (F/W) stations to improve international safeguards at enrichment plants. A key question that must be resolved is what is the necessary frequency of recording data from the process F/W stations? Several studies have analyzed data collected at a fixed frequency. This paper contributes to load cell process monitoring research by presenting an analysis of Monte Carlo simulations to determine the expected errors caused by low frequency sampling and its impact on material balance calculations.

  15. Analysis of the effectiveness of gas centrifuge enrichment plants advanced safeguards

    SciTech Connect

    Boyer, Brian David [Los Alamos National Laboratory; Erpenbeck, Heather H [Los Alamos National Laboratory; Miller, Karen A [Los Alamos National Laboratory; Swinjoe, Martyn T [Los Alamos National Laboratory; Ianakiev, Kiril D [Los Alamos National Laboratory; Marlow, Johnna B [Los Alamos National Laboratory

    2010-01-01

    Current safeguards approaches used by the International Atomic Energy Agency (IAEA) at gas centrifuge enrichment plants (GCEPs) need enhancement in order to verify declared low-enriched uranium (LEU) production, detect undeclared LEU production and detect highly enriched uranium (HEU) production with adequate detection probability using non destructive assay (NDA) techniques. At present inspectors use attended systems, systems needing the presence of an inspector for operation, during inspections to verify the mass and 235U enrichment of declared UF6 containers used in the process of enrichment at GCEPs. This paper contains an analysis of possible improvements in unattended and attended NDA systems including process monitoring and possible on-site destructive assay (DA) of samples that could reduce the uncertainty of the inspector's measurements. These improvements could reduce the difference between the operator's and inspector's measurements providing more effective and efficient IAEA GCEPs safeguards. We also explore how a few advanced safeguards systems could be assembled for unattended operation. The analysis will focus on how unannounced inspections (UIs), and the concept of information-driven inspections (IDS) can affect probability of detection of the diversion of nuclear materials when coupled to new GCEPs safeguards regimes augmented with unattended systems.

  16. Gas centrifuge enrichment plants inspection frequency and remote monitoring issues for advanced safeguards implementation

    SciTech Connect

    Boyer, Brian David [Los Alamos National Laboratory; Erpenbeck, Heather H [Los Alamos National Laboratory; Miller, Karen A [Los Alamos National Laboratory; Ianakiev, Kiril D [Los Alamos National Laboratory; Reimold, Benjamin A [Los Alamos National Laboratory; Ward, Steven L [Los Alamos National Laboratory; Howell, John [GLASGOW UNIV.

    2010-09-13

    Current safeguards approaches used by the IAEA at gas centrifuge enrichment plants (GCEPs) need enhancement in order to verify declared low enriched uranium (LEU) production, detect undeclared LEU production and detect high enriched uranium (BEU) production with adequate probability using non destructive assay (NDA) techniques. At present inspectors use attended systems, systems needing the presence of an inspector for operation, during inspections to verify the mass and {sup 235}U enrichment of declared cylinders of uranium hexafluoride that are used in the process of enrichment at GCEPs. This paper contains an analysis of how possible improvements in unattended and attended NDA systems including process monitoring and possible on-site destructive analysis (DA) of samples could reduce the uncertainty of the inspector's measurements providing more effective and efficient IAEA GCEPs safeguards. We have also studied a few advanced safeguards systems that could be assembled for unattended operation and the level of performance needed from these systems to provide more effective safeguards. The analysis also considers how short notice random inspections, unannounced inspections (UIs), and the concept of information-driven inspections can affect probability of detection of the diversion of nuclear material when coupled to new GCEPs safeguards regimes augmented with unattended systems. We also explore the effects of system failures and operator tampering on meeting safeguards goals for quantity and timeliness and the measures needed to recover from such failures and anomalies.

  17. In-Born Radio Frequency Identification Devices for Safeguards Use at Gas-Centrifuge Enrichment Plants

    SciTech Connect

    Ward,R.; Rosenthal,M.

    2009-07-12

    Global expansion of nuclear power has made the need for improved safeguards measures at Gas Centrifuge Enrichment Plants (GCEPs) imperative. One technology under consideration for safeguards applications is Radio Frequency Identification Devices (RFIDs). RFIDs have the potential to increase IAEA inspector"s efficiency and effectiveness either by reducing the number of inspection visits necessary or by reducing inspection effort at those visits. This study assesses the use of RFIDs as an integral component of the "Option 4" safeguards approach developed by Bruce Moran, U.S. Nuclear Regulatory Commission (NRC), for a model GCEP [1]. A previous analysis of RFIDs was conducted by Jae Jo, Brookhaven National Laboratory (BNL), which evaluated the effectiveness of an RFID tag applied by the facility operator [2]. This paper presents a similar evaluation carried out in the framework of Jo’s paper, but it is predicated on the assumption that the RFID tag is applied by the manufacturer at the birth of the cylinder, rather than by the operator. Relevant diversion scenarios are examined to determine if RFIDs increase the effectiveness and/ or efficiency of safeguards in these scenarios. Conclusions on the benefits offered to inspectors by using in-born RFID tagging are presented.

  18. A Robust Infrastructure Design for Gas Centrifuge Enrichment Plant Unattended Online Enrichment Monitoring

    SciTech Connect

    Younkin, James R [ORNL; Rowe, Nathan C [ORNL; Garner, James R [ORNL

    2012-01-01

    An online enrichment monitor (OLEM) is being developed to continuously measure the relative isotopic composition of UF6 in the unit header pipes of a gas centrifuge enrichment plant (GCEP). From a safeguards perspective, OLEM will provide early detection of a facility being misused for production of highly enriched uranium. OLEM may also reduce the number of samples collected for destructive assay and if coupled with load cell monitoring can provide isotope mass balance verification. The OLEM design includes power and network connections for continuous monitoring of the UF6 enrichment and state of health of the instrument. Monitoring the enrichment on all header pipes at a typical GCEP could require OLEM detectors on each of the product, tails, and feed header pipes. If there are eight process units, up to 24 detectors may be required at a modern GCEP. Distant locations, harsh industrial environments, and safeguards continuity of knowledge requirements all place certain demands on the network robustness and power reliability. This paper describes the infrastructure and architecture of an OLEM system based on OLEM collection nodes on the unit header pipes and power and network support nodes for groupings of the collection nodes. A redundant, self-healing communications network, distributed backup power, and a secure communications methodology. Two candidate technologies being considered for secure communications are the Object Linking and Embedding for Process Control Unified Architecture cross-platform, service-oriented architecture model for process control communications and the emerging IAEA Real-time And INtegrated STream-Oriented Remote Monitoring (RAINSTORM) framework to provide the common secure communication infrastructure for remote, unattended monitoring systems. The proposed infrastructure design offers modular, commercial components, plug-and-play extensibility for GCEP deployments, and is intended to meet the guidelines and requirements for unattended and remotely monitored safeguards systems.

  19. Centrifugal pump fuel system

    Microsoft Academic Search

    M. E. McGlone; L. J. Larkins; R. O. Johnson; K. A. Moeller

    1993-01-01

    A centrifugal pump fuel system for an engine driven fuel pump for an aircraft gas turbine engine is described comprising: a centrifugal pump having at constant speed rising head\\/flow characteristic at low flows; a plumbing system receiving flow from the pump, and having at least one control valve located down stream of and defining a discrete volume of the plumbing

  20. Centrifuge blotting.

    PubMed

    Paul, Jinny

    2015-01-01

    Centrifuge blotting is an efficient and convenient method for elution and transfer of proteins from a polyacrylamide gel onto a polyvinylidene difluoride (PVDF) membrane by centrifugation. PMID:26044021

  1. Gas-liquid Two Phase Flow Modelling of Incompressible Fluid and Experimental Validation Studies in Vertical Centrifugal Casting

    NASA Astrophysics Data System (ADS)

    Zhou, J. X.; Shen, X.; Yin, Y. J.; Guo, Z.; Wang, H.

    2015-06-01

    In this paper, Gas-liquid two phase flow mathematic models of incompressible fluid were proposed to explore the feature of fluid under certain centrifugal force in vertical centrifugal casting (VCC). Modified projection-level-set method was introduced to solve the mathematic models. To validate the simulation results, two methods were used in this study. In the first method, the simulation result of basic VCC flow process was compared with its analytic solution. The relationship between the numerical solution and deterministic analytic solution was presented to verify the correctness of numerical algorithms. In the second method, systematic water simulation experiments were developed. In this initial experiment, special experimental vertical centrifugal device and casting shapes were designed to describe typical mold-filling processes in VCC. High speed camera system and data collection devices were used to capture flow shape during the mold-filling process. Moreover, fluid characteristic at different rotation speed (from 40rpm, 60rpmand 80rpm) was discussed to provide comparative resource for simulation results. As compared with the simulation results, the proposed mathematical models could be proven and the experimental design could help us advance the accuracy of simulation and further studies for VCC.

  2. Splitter-bladed centrifugal compressor impeller designed for automotive gas turbine application. [at the Lewis Research Center

    NASA Technical Reports Server (NTRS)

    Pampreen, R. C.

    1977-01-01

    Mechanical design and fabrication of two splitter-bladed centrifugal compressor impellers were completed for rig testing at NASA Lewis Research Center. These impellers were designed for automotive gas turbine application. The mechanical design was based on NASA specifications for blade-shape and flowpath configurations. The contractor made engineering drawings and performed calculations for mass and center-of-gravity, for stress and vibration analyses, and for shaft critical speed analysis. One impeller was machined to print; the other had a blade height and exit radius of 2.54 mm larger than print dimensions.

  3. Novel approach to the computation of axisymmetric countercurrent patterns in gas centrifuges

    NASA Astrophysics Data System (ADS)

    Cloutman, L. D.

    1980-02-01

    A numerical algorithm based on finite Fourier Chebyshev transforms for solving the total reflux, thermal drive centrifuge problem is presented. The method should be capable of providing steady state solutions with excellent resolution in a few minutes of computer time. The same technique may be easily applied to other problems, including the isotope diffusion equation. A simple diffusion equation is solved to show certain aspects of the numerical method, in particular, its excellent convergence properties.

  4. RESEARCH AND DEVELOPMENT OF AN INTEGRAL SEPARATOR FOR A CENTRIFUGAL GAS PROCESSING FACILITY

    SciTech Connect

    LANCE HAYS

    2007-02-27

    A COMPACT GAS PROCESSING DEVICE WAS INVESTIGATED TO INCREASE GAS PRODUCTION FROM REMOTE, PREVIOUSLY UN-ECONOMIC RESOURCES. THE UNIT WAS TESTED ON AIR AND WATER AND WITH NATURAL GAS AND LIQUID. RESULTS ARE REPORTED WITH RECOMMENDATIONS FOR FUTURE WORK.

  5. The production characteristics of a solution gas-drive reservoir as measured on a centrifugal model 

    E-print Network

    Goodwin, Robert Jennings

    1955-01-01

    and Fluid Mixing Cylinder Physical Characteristics oi' Kerosene-Natural Gas Mixtures 1 and 2 at 110 F Physical Characteristics of Cetus Oil ? Natural Gas Mixtures 3 and 4 at 110o F Pressure-Viscosity Relati. onshi. ps at 110 F for Kerosene- Natural Gas... density (gm/cc) Fluid gl Fluid P2 Fluid. 83 Fluid /t'4 Kerosene Kerosene Cetus oil- Cetus oil?' Nat. gas?~ Nat. gas?~ Nat. gas'~ Nat. gas"+ 1. 29 1. 29 25. 62 25. 62 . 782 . 782 . 902 . 902 Texas Company trade-name ?e' Gas analysis...

  6. Analytical calibration of the two-geometry method for uranium enrichment verification in a gas centrifuge

    NASA Astrophysics Data System (ADS)

    Close, D. A.; Atwater, H. F.

    1990-09-01

    The two-geometry method is an approved technique to verify the uranium enrichment of UF 6 in centrifuge cascade header pipes. Two analytical calculations, Monte Carlo and numerical integration of expressions derived from geometrical arguments, have been applied to determine the detector geometry constants to simplify optimizing the pair of detector collimator geometries. Comparisons are presented for two pairs of collimators: an uncollimated and a collimated geometry; and a parallel collimated and a perpendicular collimated geometry. Both Monte Carlo and numerical integration techniques qualitatively predict the characteristics of this enrichment measurement.

  7. Simulation of the heat exchange between the supersonic flow and the stationary body in a gas centrifuge

    NASA Astrophysics Data System (ADS)

    Zvonarev, K. V.; Seleznev, V. D.; Tokmantsev, V. I.; Abramov, Yu. V.

    2012-11-01

    We have made comparative calculations of the heat exchange in the subpersonic flow of gaseous UF6 around the stationary cylindrical body inside the rotating rotor of the gas centrifuge. It has been revealed that the integral heat flux from the gas to the body calculated with the use of the ANSYS-CFX program complex from the viewpoint of the continuum model is much smaller than the heat flow calculated by the Monte Carlo method of direct statistical simulation. Estimates show that under the conditions being considered the boundary layer on the surface of the body has no time to be formed and has a thickness of the order of the mean free path of the gas molecules and, therefore, the use of the methods of continuum mechanics in this region is incorrect. On the contrary, the method of direct statistical simulation permits taking into account the interaction of gas molecules directly with the surface of the streamline body and obtaining more correct results.

  8. Numerical studies of the isotope distribution in a gas centrifuge using a tapered, double-parabolic axial flow

    NASA Astrophysics Data System (ADS)

    Park, J. E.

    The isotope distribution in a gas centrifuge was solved by the Rome machine. The axial mass flux was specified to be of double parabolic form, with downflow in the region nearest the outer wall and upflow adjacent to the downflow. The magnitude of the upflow was varied axially to produce a tapered crossflow. Parameters for the axial taper were selected and the feed was selected to maximize the separative work. The numerical error due to the finite difference mesh was investigated. Two radial and five axial meshes were used. The separative works calculated using these meshes are presented, allowing an assessment of the error in the numerical technique. The effect of temperature variation on isotopic distribution was studied. Using a fixed double parabolic axial profile, the temperature was varied in a systematic fashion, which induced local changes in the pressure diffusion and the mass diffusion coefficient. The changes led to variations in the predicted values for separative work.

  9. Procedures for the calculation of the separative performance of a countercurrent gas centrifuge

    NASA Astrophysics Data System (ADS)

    Vonhalle, E.

    1981-07-01

    The approximations used in the development of the standard Onsager-Cohen gradient equation produce results which depart from the more detailed solutions presented in one direction in the enriching section and in the other direction in the stripping section and the errors therefore tend to cancel for the machine as a whole. It follows that for a centrifuge in which most of the bowl is used as an enriching section or as a stripping section this cancellation would not occur and some appreciable error would result from the use of the standard Onsager-Cohen gradient equation. A modified Onsager-Cohen gradient equation is therefore recommended in preference to the standard Onsager-Cohen gradient equation. It is shown in the results of calculations that indeed very little effect is observed by neglecting the term in the gradient equation containing the second derivative of the concentration.

  10. Centrifugal extraction of highly enriched tin isotopes and increase of specific activity of the radionuclide 119mSn on the gas centrifuge cascade

    NASA Astrophysics Data System (ADS)

    Suvorov, I. A.; Tcheltsov, A. N.; Sosnin, L. Yu.; Sazikin, A. A.; Rudnev, A. I.

    2002-03-01

    This work contains the results of research on centrifugal enrichment of 118Sn isotope followed by irradiation and, finally, a second centrifugal enrichment to produce high specific activity 119mSn. Non-steady-state separation methods were used for the effective extraction of the radionuclide 119mSn from the irradiated target. As a result of this work, radiation sources based on 119mSn were obtained with a specific activity of 500 mCi/g. This is 100 times greater than the specific activity obtained after irradiation in the reactor alone. In addition, the sources had an previously unattainable radio-purity ratio of 113Sn/ 119mSn of approximately 10 -6.

  11. Centrifugal adsorption system

    NASA Technical Reports Server (NTRS)

    Gonda, Steve R. (Inventor); Tsao, Yow-Min D. (Inventor); Lee, Wenshan (Inventor)

    2006-01-01

    A gas-liquid separator uses a helical passageway to impart a spiral motion to a fluid passing therethrough. The centrifugal force generated by the spiraling motion urges the liquid component of the fluid radially outward which forces the gas component radially inward. The gas component is then separated through a gas-permeable, liquid-impervious membrane and discharged through a central passageway. A filter material captures target substances contained in the fluid.

  12. FEMO, A FLOW AND ENRICHMENT MONITOR FOR VERIFYING COMPLIANCE WITH INTERNATIONAL SAFEGUARDS REQUIREMENTS AT A GAS CENTRIFUGE ENRICHMENT FACILITY

    SciTech Connect

    Gunning, John E [ORNL; Laughter, Mark D [ORNL; March-Leuba, Jose A [ORNL

    2008-01-01

    A number of countries have received construction licenses or are contemplating the construction of large-capacity gas centrifuge enrichment plants (GCEPs). The capability to independently verify nuclear material flows is a key component of international safeguards approaches, and the IAEA does not currently have an approved method to continuously monitor the mass flow of 235U in uranium hexafluoride (UF6) gas streams. Oak Ridge National Laboratory is investigating the development of a flow and enrichment monitor, or FEMO, based on an existing blend-down monitoring system (BDMS). The BDMS was designed to continuously monitor both 235U mass flow and enrichment of UF6 streams at the low pressures similar to those which exists at GCEPs. BDMSs have been installed at three sites-the first unit has operated successfully in an unattended environment for approximately 10 years. To be acceptable to GCEP operators, it is essential that the instrument be installed and maintained without interrupting operations. A means to continuously verify flow as is proposed by FEMO will likely be needed to monitor safeguards at large-capacity plants. This will enable the safeguards effectiveness that currently exists at smaller plants to be maintained at the larger facilities and also has the potential to reduce labor costs associated with inspections at current and future plants. This paper describes the FEMO design requirements, operating capabilities, and development work required before field demonstration.

  13. Centrifugal compressors

    Microsoft Academic Search

    R. L. Elder; C. P. Forster

    1987-01-01

    Design of centrifugal compressors and performance prediction methods are presented. Impeller work equation, impeller velocity triangles, impeller sweepback, overall pressure rise characteristics, surges, and design analysis are treated.

  14. Centrifugal Compressor Aeroelastic Analysis Code

    Microsoft Academic Search

    Theo G. Keith Jr.; Rakesh Srivastava

    2002-01-01

    Centrifugal compressors are very widely used in the turbomachine industry where low mass flow rates are required. Gas turbine engines for tanks, rotorcraft and small jets rely extensively on centrifugal compressors for rugged and compact design. These compressors experience problems related with unsteadiness of flowfields, such as stall flutter, separation at the trailing edge over diffuser guide vanes, tip vortex

  15. Optical-fibre sensor system for monitoring the performance of the gas propellant centrifuge separator of a spacecraft

    NASA Astrophysics Data System (ADS)

    Romo-Medrano, Katya E.; Khotiaintsev, Sergei N.; García-Garduño, Victor

    2004-08-01

    An optical-fibre sensor system is presented for monitoring void fraction distribution in a spacecraft's gas and propellant centrifuge separator. The system could be used at the separator development stage or for monitoring, during ground tests, the elements of the spacecraft propulsion system. Our sensor system employs an array of point optical-fibre refractometric transducers installed in the form of several linear radial arrays on the separator rotating blades. We employed a small-size hemispherical optical detection element as the transducer and we optimized its parameters through numerical ray-tracing. The aim is to minimize the effect of the thin film of liquid that forms on the transducer's surface in this application. The features of this sensor system are: (1) an efficient matrix-type multiplexing scheme, (2) the installation of the main optoelectronic unit of the sensor in a hermetically sealed container inside the separator tank located on the rotating shaft and (3) the spark-proof and explosion-proof design of the sensor circuits and elements. The sensor is simple, reliable, low-cost and is capable of withstanding the factors involved during operation of the propulsion system such as cryogenic temperatures and chemically aggressive liquids. The novel elements and design concepts implemented in this sensor system can also find applications in other sensors for spacecraft propulsion systems and also in a variety of optical-fibre sensors used in scientific research and industry.

  16. Numerical Hydrodynamics from Gas-Kinetic Theory

    Microsoft Academic Search

    Kevin H. Prendergast; Kun Xu

    1993-01-01

    A new high-resolution numerical hydrodynamic scheme is developed from considerations of gas-kinetic theory. This Boltzmann-type scheme uses the particle distribution function, and follows its evolution to evaluate the numerical fluxes. The intrinsic multidimensional property in the evolution stage of gas distribution function distinguishes it from any other high order upwind scheme. From approximate Boltzmann equation, the Navier-Stokes equations can be

  17. Application of Condition-Based Monitoring Techniques for Remote Monitoring of a Simulated Gas Centrifuge Enrichment Plant

    SciTech Connect

    Hooper, David A [ORNL; Henkel, James J [ORNL; Whitaker, Michael [ORNL

    2012-01-01

    This paper presents research into the adaptation of monitoring techniques from maintainability and reliability (M&R) engineering for remote unattended monitoring of gas centrifuge enrichment plants (GCEPs) for international safeguards. Two categories of techniques are discussed: the sequential probability ratio test (SPRT) for diagnostic monitoring, and sequential Monte Carlo (SMC or, more commonly, particle filtering ) for prognostic monitoring. Development and testing of the application of condition-based monitoring (CBM) techniques was performed on the Oak Ridge Mock Feed and Withdrawal (F&W) facility as a proof of principle. CBM techniques have been extensively developed for M&R assessment of physical processes, such as manufacturing and power plants. These techniques are normally used to locate and diagnose the effects of mechanical degradation of equipment to aid in planning of maintenance and repair cycles. In a safeguards environment, however, the goal is not to identify mechanical deterioration, but to detect and diagnose (and potentially predict) attempts to circumvent normal, declared facility operations, such as through protracted diversion of enriched material. The CBM techniques are first explained from the traditional perspective of maintenance and reliability engineering. The adaptation of CBM techniques to inspector monitoring is then discussed, focusing on the unique challenges of decision-based effects rather than equipment degradation effects. These techniques are then applied to the Oak Ridge Mock F&W facility a water-based physical simulation of a material feed and withdrawal process used at enrichment plants that is used to develop and test online monitoring techniques for fully information-driven safeguards of GCEPs. Advantages and limitations of the CBM approach to online monitoring are discussed, as well as the potential challenges of adapting CBM concepts to safeguards applications.

  18. A parametric starting study of an axial-centrifugal gas turbine engine using a one-dimensional dynamic engine model and comparisons to experimental results. Part 1: Model development and facility description

    Microsoft Academic Search

    A. K. Owen; A. Daugherty; D. Garrard; H. C. Reynolds; R. D. Wright

    1999-01-01

    A generic one-dimensional gas turbine engine model, developed at the Arnold Engineering Development Center, has been configured to represent the gas generator of a General Electric axial-centrifugal gas turbine engine in the six kg\\/sec airflow class. The model was calibrated against experimental test results for a variety of initial conditions to insure that the model accurately represented the engine over

  19. A parametric starting study of an axial-centrifugal gas turbine engine using a one-dimensional dynamic engine model and comparisons to experimental results. Part 2: Simulation calibration and trade-off study

    Microsoft Academic Search

    A. K. Owen; A. Daugherty; D. Garrard; H. C. Reynolds; R. D. Wright

    1999-01-01

    A generic one-dimensional gas turbine engine model, developed at the Arnold Engineering Development Center, has been configured to represent the gas generator of a General Electric axial-centrifugal gas turbine engine in the six-kg\\/sec airflow class. The model was calibrated against experimental test results for a variety of initial conditions to insure that the model accurately represented the engine over the

  20. Centrifugal Compressor Aeroelastic Analysis Code

    NASA Astrophysics Data System (ADS)

    Keith, Theo G., Jr.; Srivastava, Rakesh

    2002-01-01

    Centrifugal compressors are very widely used in the turbomachine industry where low mass flow rates are required. Gas turbine engines for tanks, rotorcraft and small jets rely extensively on centrifugal compressors for rugged and compact design. These compressors experience problems related with unsteadiness of flowfields, such as stall flutter, separation at the trailing edge over diffuser guide vanes, tip vortex unsteadiness, etc., leading to rotating stall and surge. Considerable interest exists in small gas turbine engine manufacturers to understand and eventually eliminate the problems related to centrifugal compressors. The geometric complexity of centrifugal compressor blades and the twisting of the blade passages makes the linear methods inapplicable. Advanced computational fluid dynamics (CFD) methods are needed for accurate unsteady aerodynamic and aeroelastic analysis of centrifugal compressors. Most of the current day industrial turbomachines and small aircraft engines are designed with a centrifugal compressor. With such a large customer base and NASA Glenn Research Center being, the lead center for turbomachines, it is important that adequate emphasis be placed on this area as well. Currently, this activity is not supported under any project at NASA Glenn.

  1. Centrifugal pump fuel system

    SciTech Connect

    McGlone, M.E.; Larkins, L.J.; Johnson, R.O.; Moeller, K.A.

    1993-06-22

    A centrifugal pump fuel system for an engine driven fuel pump for an aircraft gas turbine engine is described comprising: a centrifugal pump having at constant speed rising head/flow characteristic at low flows; a plumbing system receiving flow from the pump, and having at least one control valve located down stream of and defining a discrete volume of the plumbing system; a plumbing resonant frequency defined by the discrete volume, the geometry of the plumbing system, and the bulk modulus of the fuel; a pressure difference regulating valve located adjacent to the discharge of the pump, up stream of the vast majority of the discrete volume; and the frequency response of the regulating valve being significantly less than the frequency response of the plumbing system such that the response of the regulating valve is attenuated at the resonant frequency of the plumbing system.

  2. Centrifugal pyrocontactor

    DOEpatents

    Chow, L.S.; Leonard, R.A.

    1993-10-19

    A method is described for mixing and separating immiscible liquid salts and liquid metals in a centrifugal contractor. The method includes introducing the liquids into an annular mixing zone and intensely mixing the liquids using vertical vanes attached to a rotor cooperating with vertical baffles, a horizontal baffle, and bottom vanes attached to the contactor housing. The liquids enter the contactor in the range of 700-800 degrees Celsius. The liquids are separated in the rotor into a dense phase and a light phase which are discharged from the contactor. 6 figures.

  3. Monitoring the enrichment of the UF/sub 6/ in the pipework of a gas centrifuge enrichment plant

    SciTech Connect

    Packer, T.W.; Close, D.A.; Pratt, J.C.

    1987-01-01

    Research in the UK and the US has resulted in the development of a nondestructive assay instrument which can confirm the presence of low enriched uranium, on a rapid Go, No-Go basis, in cascade header pipework in the centrifuge enrichment plant at Capenhurst. The instrument is based on gamma-ray spectrometry and x-ray fluorescence analysis. It allows pipes, 120mm outer diameter, to be inspected in a total measurement time of approximately 30 minutes. This paper describes the techniques developed and includes the results obtained during a demonstration to, and preliminary in-plant measurements by, members of the IAEA and EURATOM Inspectorates at Capenhurst.

  4. Constraints complicate centrifugal compressor depressurization

    SciTech Connect

    Key, B. (Hoover and Keith Inc., Houston, TX (United States)); Colbert, F.L. (Paragon Engineering Services Inc., Houston, TX (United States))

    1993-05-10

    Blowdown of a centrifugal compressor is complicated by process constraints that might require slowing the depressurization rate and by mechanical constraints for which a faster rate might be preferred. The paper describes design constraints such as gas leaks; thrust-bearing overload; system constraints; flare extinguishing; heat levels; and pressure drop.

  5. Centrifuges Biological Safety

    E-print Network

    Pawlowski, Wojtek

    Centrifuges Biological Safety General Biosafety Practices (GBP) Why You Should Care Centrifuges use centrifuges go fast enough to pose dangers. Mechanical hazards can include stress to the rotor metal, fatigue, that lead to accidents involving centrifuges. Hazardous materials can include biologicals and chemicals

  6. Centrifuges MicrocentrifugesMicrocentrifuges

    E-print Network

    Collins, Gary S.

    2.8 #12;Centrifuges TypesTypes MicrocentrifugesMicrocentrifuges Low/high speedLow/high speed,000 2.8 #12;Centrifuges Hazards nn Mechanical failure of machineMechanical failure of machine nn Lab Operator errorOperator error 2.8 #12;Centrifuges ­Safety Tip Always remember to balance the centrifuge

  7. Centrifugal Adsorption Cartridge System

    NASA Technical Reports Server (NTRS)

    Gonda, Steve R.; Tsao, Yow-Min D.; Lee, Wenshan

    2004-01-01

    The centrifugal adsorption cartridge system (CACS) is an apparatus that recovers one or more bioproduct(s) from a dilute aqueous solution or suspension flowing from a bioreactor. The CACS can be used both on Earth in unit gravity and in space in low gravity. The CACS can be connected downstream from the bioreactor; alternatively, it can be connected into a flow loop that includes the bioreactor so that the liquid can be recycled. A centrifugal adsorption cartridge in the CACS (see figure) includes two concentric cylinders with a spiral ramp between them. The volume between the inner and outer cylinders, and between the turns of the spiral ramp is packed with an adsorbent material. The inner cylinder is a sieve tube covered with a gas-permeable, hydrophobic membrane. During operation, the liquid effluent from the bioreactor is introduced at one end of the spiral ramp, which then constrains the liquid to flow along the spiral path through the adsorbent material. The spiral ramp also makes the flow more nearly uniform than it would otherwise be, and it minimizes any channeling other than that of the spiral flow itself. The adsorbent material is formulated to selectively capture the bioproduct(s) of interest. The bioproduct(s) can then be stored in bound form in the cartridge or else eluted from the cartridge. The centrifugal effect of the spiral flow is utilized to remove gas bubbles from the liquid. The centrifugal effect forces the bubbles radially inward, toward and through the membrane of the inner cylinder. The gas-permeable, hydrophobic membrane allows the bubbles to enter the inner cylinder while keeping the liquid out. The bubbles that thus enter the cylinder are vented to the atmosphere. The spacing between the ramps determines rate of flow along the spiral, and thereby affects the air-bubble-removal efficiency. The spacing between the ramps also determines the length of the fluid path through the cartridge adsorbent, and thus affects the bioproduct-capture efficiency of the cartridge. Depending on the application, several cartridges could be connected in a serial or parallel flow arrangement. A parallel arrangement can be used to increase product-capturing and flow capacities while maintaining a low pressure drop. A serial arrangement can be used to obtain high product-capturing capacity; alternatively, series-connected cartridges can be packed with different adsorbents to capture different bioproducts simultaneously.

  8. The Maryland Centrifugal Experiment (MCX) has been built to study the confinement of supersonically-rotating plasmas and velocity shear stabilization of MHD instabilities. Theory

    E-print Network

    Anlage, Steven

    ABSTRACT The Maryland Centrifugal Experiment (MCX) has been built to study the confinement the MCX centrifugal confinement scheme are presented here with the data and analysis from its first nine that this centrifugal confinement scheme provides good stability and confinement at the temperatures and densities under

  9. Gas of wormholes in Euclidean quantum field theory

    E-print Network

    E. P. Savelova

    2012-11-28

    We model the spacetime foam picture by a gas of wormholes in Euclidean field theory. It is shown that at large distances the presence of such a gas leads merely to a renormalization of mass and charge values. We also demonstrate that there exist a class of specific distributions of point-like wormholes which essentially change the ultraviolet behavior of Green functions and lead to finite quantum field theories.

  10. Brane gas cosmology in M theory: Late time behavior

    Microsoft Academic Search

    Richard Easther; Brian R. Greene; Mark G. Jackson; Daniel Kabat

    2003-01-01

    We investigate the late-time behavior of a universe containing a supergravity gas and wrapped 2-branes in the context of M theory compactified on T10. The supergravity gas tends to drive uniform expansion, while the branes impede the expansion of the directions about which they are wrapped. Assuming spatial homogeneity, we study the dynamics both numerically and analytically. At late times

  11. Centrifuging a Sample

    NSDL National Science Digital Library

    The demonstration on this page shows a technique that should not be used by undergraduate chemistry laboratory. This video shows what happens to sample in a centrifuge while the centrifuge is on, and the result of stopping the centrifuge improperly. A narrative is included in this video: The centrifuging process allows the solvent to completely settle out. The jarring caused by hand braking destroys the distinct separation between supernatant and solid.

  12. Weak turbulence theory of enhanced gas ionization by plasma flow

    Microsoft Academic Search

    A. A. Galeev

    1981-01-01

    A quasilinear theory of collisionless energy transfer from a counterstreaming plasma-gas flow to electrons is presented. The critical ionization velocity was reexamined. It is recognized that this phenomenon requires enhanced heating of electrons, via some hypothetical collisionless interaction between plasma species, that can be studied by a well developed weak plasma turbulence theory. Since a plasma cannot interact collisionlessly with

  13. Development of turbine driven centrifugal compressors for non-condensible gas removal at geothermal power plants. Final report

    SciTech Connect

    NONE

    1997-12-16

    Initial field tests have been completed for a Non-Condensible Gas (NCG) turbocompressor for geothermal power plants. It provides alternate technology to steam-jet ejectors and liquid-ring vacuum pumps that are currently used for NCG removal. It incorporates a number of innovative design features to enhance reliability, reduce steam consumption and reduce O&M costs. During initial field tests, the turbocompressor has been on-line for more than 4500 hours as a third stage compressor at The Geysers Unit 11 Power Plant. Test data indicates its overall efficiency is about 25% higher than a liquid-ring vacuum pump, and 250% higher than a steam-jet ejector when operating with compressor inlet pressures of 12.2 in-Hga and flow rates over 20,000 lbm/hr.

  14. On the theory of countercurrent flow in a rotating viscous heat-conducting gas

    NASA Astrophysics Data System (ADS)

    Belotserkovskii, O. M.; Betelin, V. B.; Borisevich, V. D.; Denisenko, V. V.; Eriklintsev, I. V.; Kozlov, S. A.; Konyukhov, A. V.; Oparin, A. M.; Troshkin, O. V.

    2011-02-01

    The countercurrent flow in a gas centrifuge is simulated. Mechanical and thermal methods for its excitation are discussed; thermal restructuring, the thermal control of the velocity field, and a shift in the inversion point are analyzed; and the formation of overtone flows in the rarefaction zone is studied.

  15. USE OF MAILBOX APPROACH, VIDEO SURVEILLANCE, AND SHORT-NOTICE RANDOM INSPECTIONS TO ENHANCE DETECTION OF UNDECLARED LEU PRODUCTION AT GAS CENTRIFUGE ENRICHMENT PLANTS.

    SciTech Connect

    BOYER, B.D.; GORDON, D.M.; JO, J.

    2006-07-16

    Current safeguards approaches used by the IAEA at gas centrifuge enrichment plants (GCEPs) need enhancement in order to detect undeclared LEU production with adequate detection probability. ''Mailbox'' declarations have been used in the last two decades to verify receipts, production, and shipments at some bulk-handling facilities (e.g., fuel-fabrication plants). The operator declares the status of his plant to the IAEA on a daily basis using a secure ''Mailbox'' system such as a secure tamper-resistant computer. The operator agrees to hold receipts and shipments for a specified period of time, along with a specified number of annual inspections, to enable inspector access to a statistically large enough population of UF{sub 6} cylinders and fuel assemblies to achieve the desired detection probability. The inspectors can access the ''Mailbox'' during randomly timed inspections and then verify the operator's declarations for that day. Previously, this type of inspection regime was considered mainly for verifying the material balance at fuel-fabrication, enrichment, and conversion plants. Brookhaven National Laboratory has expanded the ''Mailbox'' concept with short-notice random inspections (SNRIs), coupled with enhanced video surveillance, to include declaration and verification of UF{sub 6} cylinder operational data to detect activities associated with undeclared LEU production at GCEPs. Since the ''Mailbox'' declarations would also include data relevant to material-balance verification, these randomized inspections would replace the scheduled monthly interim inspections for material-balance purposes; in addition, the inspectors could simultaneously perform the required number of Limited-Frequency Unannounced Access (LFUA) inspections used for HEU detection. This approach would provide improved detection capabilities for a wider range of diversion activities with not much more inspection effort than at present.

  16. Boundary layers in centrifugal compressors

    Microsoft Academic Search

    R. C. Dean Jr.

    1974-01-01

    The utility of boundary-layer theory in the design of centrifugal compressors is demonstrated. Boundary-layer development in the diffuser entry region is shown to be important to stage efficiency. The result of an earnest attempt to analyze this boundary layer with the best tools available is displayed. Acceptable prediction accuracy was not achieved. The inaccuracy of boundary-layer analysis in this case

  17. A parametric starting study of an axial-centrifugal gas turbine engine using a one-dimensional dynamic engine model and comparisons to experimental results. Part 2: Simulation calibration and trade-off study

    SciTech Connect

    Owen, A.K.; Daugherty, A. [Army Vehicle Propulsion Directorate, Cleveland, OH (United States); Garrard, D. [Sverdrup Technology, Inc./AEDC Group, Arnold AFB, TN (United States); Reynolds, H.C.; Wright, R.D. [General Electric Corp., Lynn, MA (United States)

    1999-07-01

    A generic one-dimensional gas turbine engine model, developed at the Arnold Engineering Development Center, has been configured to represent the gas generator of a General Electric axial-centrifugal gas turbine engine in the six-kg/sec airflow class. The model was calibrated against experimental test results for a variety of initial conditions to insure that the model accurately represented the engine over the range of test conditions of interest. These conditions included both assisted (with a starter motor) and unassisted (altitude windmill) starts. The model was then exercised to study a variety of engine configuration modifications designed to improve its starting characteristics and thus quantify potential starting improvements for the next generation of gas turbine engines. This paper presents the model calibration results and the results of the trade-off study. A companion paper discusses the model development and describes the test facilities used to obtain the calibration data.

  18. Quantum Theory of a Gas Laser. II

    Microsoft Academic Search

    Charles R. Willis

    1968-01-01

    We generalize the method of deriving a kinetic equation for a gas laser developed in the first paper of this series to include radiation-matter correlations. As a consequence, we are able to show that the first Born approximation with asymptotic conditions which contain radiation-matter correlations is sufficient to explain the nonthermal photon distribution observed in photon-counting experiments. Our derivation includes

  19. Lattice gas hydrodynamics: Theory and simulations

    SciTech Connect

    Hasslacher, B.

    1993-01-01

    The first successful application of a microscopic analogy to create a skeleton cellular automaton and analyze it with statistical mechanical tools, was the work of Frisch, Hasslacher and Pomeau on the Navier-Stokes equation in two and three dimensions. This has become a very large research area with lattice gas models and methods being used for both fundamental investigations into the foundations of statistical mechanics and a large number of diverse applications. This present research was devoted to enlarging the fundamental scope of lattice gas models and proved successful. Since the beginning of this proposal, cellular automata have been constructed for statistical mechanical models, fluids, diffusion and shock systems in fundamental investigations. In applied areas, there are now excellent lattice gas models for complex flows through porous media, chemical reaction and combustion dynamics, multiphase flow systems, and fluid mixtures with natural boundaries. With extended cellular fluid models, one can do problems with arbitrary pairwise potentials. Recently, these have been applied to such problems as non-newtonian or polymeric liquids and a mixture of immiscible fluids passing through fractal or spongelike media in two and three dimensions. This proposal has contributed to and enlarged the scope of this work.

  20. Brane gas cosmology in M-theory: late time behavior

    Microsoft Academic Search

    Richard Easther; Brian R. Greeneab; Mark G. Jackson; Daniel Kabatc

    We investigate the late-time behavior of a universe containing a supergravity gas and wrapped 2-branes in the context of M-theory compactified on T 10. The supergravity gas tends to drive uniform expansion, while the branes impede the expansion of the directions about which they are wrapped. As- suming spatial homogeneity, we study the dynamics both numerically and analytically. At late

  1. Theory of the classical electron gas

    NASA Technical Reports Server (NTRS)

    Guernsey, R. L.

    1978-01-01

    In a previous paper Cohen and Murphy (1969) used the Meeron resummation (1958) of the Mayer diagrams (1950) to calculate the pair correlation for the classical electron gas in thermal equilibrium. They found that successive terms in the expression for the pair correlation were more and more singular for small interparticle spacing, actually dominating the Debye-Hueckel result for sufficiently small distances. This led to apparent divergence in the higher order contributions to the internal energy. The present paper shows that the apparent anomalies in the Cohen-Murphy results can be removed without further resummation by a more careful treatment of the region of small interparticle spacing. It is shown that there is really no anomalous behavior at short range in any order and all integrals in the expression for the internal energy converge.

  2. Kinetic Theory and Hydrodynamics for a Low Density Gas

    E-print Network

    James W. Dufty

    2001-09-12

    Many features of real granular fluids under rapid flow are exhibited as well by a system of smooth hard spheres with inelastic collisions. For such a system, it is tempting to apply standard methods of kinetic theory and hydrodynamics to calculate properties of interest. The domain of validity for such methods is a priori uncertain due to the inelasticity, but recent systematic studies continue to support the utility of kinetic theory and hydrodynamics as both qualitative and quantitative descriptions for many physical states. The basis for kinetic theory and hydrodynamic descriptions is discussed briefly for the special case of a low density gas.

  3. On Kinetic Theory Viscosity in a Rotating Gas

    E-print Network

    Takuya Matsuda; Eiji Hayashi

    2004-09-07

    Clarke and Pringle (2004) derived a proper viscosity formula in a rotating gas by applying mean free path theory. We study their argument in detail and show that their result can be derived with a much simpler calculational procedure and physically clearer picture.

  4. Defining the needs for non-destructive assay of UF6 feed, product, and tails at gas centrifuge enrichment plants and possible next steps

    SciTech Connect

    Boyer, Brian D [Los Alamos National Laboratory; Swinhoe, Martyn T [Los Alamos National Laboratory; Moran, Bruce W [IAEA; Lebrun, Alain [IAEA

    2009-01-01

    Current safeguards approaches used by the IAEA at gas centrifuge enrichment plants (GCEPs) need enhancement in order to detect undeclared LEU production with adequate detection probability using non destructive assay (NDA) techniques. At present inspectors use attended systems, systems needing the presence of an inspector for operation, during inspections to verify the mass and {sup 235}U enrichment of UF{sub 6} bulk material used in the process of enrichment at GCEPS. The inspectors also take destructive assay (DA) samples for analysis off-site which provide accurate, on the order of 0.1 % to 0.5% uncertainty, data on the enrichment of the UF{sub 6} feed, tails, and product. However, DA sample taking is a much more labor intensive and resource intensive exercise for the operator and inspector. Furthermore, the operator must ship the samples off-site to the IAEA laboratory which delays the timeliness of the results and contains the possibility of the loss of the continuity of knowledge of the samples during the storage and transit of the material. Use of the IAEA's inspection sampling algorithm shows that while total sample size is fixed by the total population of potential samples and its intrinsic qualities, the split of the samples into NDA or DA samples is determined by the uncertainties in the NDA measurements. Therefore, the larger the uncertainties in the NDA methods, more of the sample taken must be DA samples. Since the DA sampling is arduous and costly, improvements in NDA methods would reduce the number of DA samples needed. Furthermore, if methods of on-site analysis of the samples could be developed that have uncertainties in the 1-2% range, a lot of the problems inherent in DA sampling could be removed. The use of an unattended system that could give an overview of the entire process giving complementary data on the enrichment process as well as accurate measures of enrichment and weights of the UF{sub 6} feed, tails, and product would be a major step in enhancing the ability of NDA beyond present attended systems. The possibility of monitoring the feed, tails, and product header pipes in such a way as to gain safeguards relevant flow and enrichment information without compromising the intellectual property of the operator including proprietary equipment and operational parameters would be a huge step forward. This paper contains an analysis of possible improvements in unattended and attended NDA systems including such process monitoring and possible on-site analysis of DA samples that could reduce the uncertainty of the inspector measurements reducing the difference between the operator's and inspector's measurements providing more effective and efficient IAEA GeEPs safeguards.

  5. Dry seal applications in centrifugal compressors

    Microsoft Academic Search

    Fischbach

    1989-01-01

    Most centrifugal compressors in refineries and petrochemical plants use shaft end seals which are either controlled leakage labyrinths (nontoxic\\/nonhazardous fluids only) or some type of fluid film seals using a liquid, primarily oil, as a barrier fluid. This article discusses the emerging technology of so-called dry seals. These seals use gas as the sealing fluid medium, and control the leakage

  6. Brane gas cosmology in M theory: Late time behavior

    Microsoft Academic Search

    Richard Easther; Brian R. Greene; Mark G. Jackson; Daniel Kabat

    2003-01-01

    We investigate the late-time behavior of a universe containing a supergravity\\u000agas and wrapped 2-branes in the context of M-theory compactified on T^10. The\\u000asupergravity gas tends to drive uniform expansion, while the branes impede the\\u000aexpansion of the directions about which they are wrapped. Assuming spatial\\u000ahomogeneity, we study the dynamics both numerically and analytically. At late\\u000atimes the

  7. DESIGN INFORMATION REPORT: CENTRIFUGES

    EPA Science Inventory

    In the 1960s, manufacturers began to design centrifuges specifically for wastewater sludge applications. In addition, sludge thickening and dewatering processes were improved with the introduction of polyelectrolytes for chemical sludge conditioning. The report contains a brief d...

  8. Flank millable blade design for centrifugal compressors

    Microsoft Academic Search

    Yayun Zhou; J. Schulze; S. Schaffler

    2009-01-01

    A novel design approach for the centrifugal compressor blade is proposed in this paper. It is set up based on the offset theory and line geometry. The designed blade surface is represented as a tool path, which consists of two guide curves. It can be manufactured by flank milling method with a cylindrical cutter. The drive surface is a ruled

  9. Centrifugal casting of metal matrix composites. Ph.D. Thesis

    SciTech Connect

    Berger, R.E.

    1994-01-01

    Metal matrix composites (MMCs) have excellent properties and low material costs, but high manufacturing costs. The primary difficulty in manufacturing MMCs is in forming a tight matrix/reinforcement bond. This dissertation investigates improving the matrix/reinforcement bond through the use of high centrifugal forces. High centrifugal forces promote fiber infiltration (or particle submergence), remove gas voids, and resist particle pushing by the solidification front. Several aluminum matrix MMC samples are formed at up to 2,660 g`s. The project involves: (1) design and construction of a rotating crucible capable of a 690 C, 2,600 g-force environment; (2) a finite differences heat transfer model using an unique technique (spreadsheet iteration) which has application to engineering teaching and simple modeling problems; (3) a bubble buoyancy/surface adhesion analysis to predict maximum surface voids or bubble cling in cast materials; (4) a fluid surface tension effects analysis evaluating particle submergence into a melt, and melt infiltration into a porous media such as a fiber form; (5) creation of samples and direct visual measurement of void sizes in agreement with bubble buoyancy/surface adhesion theory; (6) performance of tests and direct evidence supporting the developed particle submergence/porous media infiltration theories; and (7) creation of samples and direct measurement of material strength under subjection to bending stress. The final conclusion is that use of high centrifugal forces in MMC manufacturing has potential, however it is only useful for large diameter fibers or particles (on the order of 200 micron) and relatively high g-forces (on the order of 2,500 g`s).

  10. Ekman boundary conditions for numerical models of centrifuge flows

    NASA Astrophysics Data System (ADS)

    Park, J. E.; Drake, J. B.

    1984-04-01

    The boundary layers which form on the ends of a gas centrifuge have received a great deal of analytical attention in predicting flows within gas centrifuges. Three basic approaches were taken in estimating the heat transfer and drag at the solid gas interfaces at the ends of a centrifuge. First, the details of the flow may be estimated numerically using finite difference techniques and a very fine grid in the vicinity of the ends. The cost in computer time and memory charges is great and the extensive detail is difficult to utilize effectively. Second, the boundary layers may simply be ignored. With this approach, the size of the finite difference mesh is controlled by other considerations which allow economically attractive simulation of centrifuge flows for many situations. The third effort is to model the boundary layers analytically and couple those models to solutions for the interior flow. Previous efforts to model the the boundary layers are reviewed.

  11. A parametric starting study of an axial-centrifugal gas turbine engine using a one-dimensional dynamic engine model and comparisons to experimental results. Part 1: Model development and facility description

    SciTech Connect

    Owen, A.K.; Daugherty, A. [Army Vehicle Propulsion Directorate, Cleveland, OH (United States); Garrard, D. [Sverdrup Technology, Inc./AEDC Group, Arnold AFB, TN (United States); Reynolds, H.C.; Wright, R.D. [General Electric Corp. Lynn, MA (United States)

    1999-07-01

    A generic one-dimensional gas turbine engine model, developed at the Arnold Engineering Development Center, has been configured to represent the gas generator of a General Electric axial-centrifugal gas turbine engine in the six kg/sec airflow class. The model was calibrated against experimental test results for a variety of initial conditions to insure that the model accurately represented the engine over the range of test conditions of interest. These conditions included both assisted (with a starter motor) and unassisted (altitude windmill) starts. The model was then exercised to study a variety of engine configuration modifications designed to improve its starting characteristics, and, thus, quantify potential starting improvements for the next generation of gas turbine engines. This paper discusses the model development and describes the test facilities used to obtain the calibration data. The test matrix for the ground level testing is also presented. A companion paper presents the model calibration result and the results of the trade-off study.

  12. Brane gas cosmology in M theory: Late time behavior

    NASA Astrophysics Data System (ADS)

    Easther, Richard; Greene, Brian R.; Jackson, Mark G.; Kabat, Daniel

    2003-06-01

    We investigate the late-time behavior of a universe containing a supergravity gas and wrapped 2-branes in the context of M theory compactified on T10. The supergravity gas tends to drive uniform expansion, while the branes impede the expansion of the directions about which they are wrapped. Assuming spatial homogeneity, we study the dynamics both numerically and analytically. At late times the radii obey power laws which are determined by the brane wrapping numbers, leading to interesting hierarchies of scale between the wrapped and unwrapped dimensions. The biggest hierarchy that could evolve from an initial thermal fluctuation produces three large unwrapped dimensions. We also study configurations corresponding to string winding, in which the M2-branes are all wrapped around the (small) 11th dimension, and show that this recovers the scenario discussed by Brandenberger and Vafa.

  13. Attack on centrifugal costs

    SciTech Connect

    Murray, P.F.

    1986-03-01

    The Monsanto Chocolate Bayou plant has had an aggressive and successful energy conservation program. The combined efforts have resulted in a 80% reduction in unit energy consumption compared to 1972. The approach of using system audits to optimize fluid systems was developed. Since most of the fluid movers are centrifugal, the name Centrifugal Savings Task Force was adopted. There are three tools that are particularly valuable in optimizing fluid systems. First, a working level understanding of the Affinity Laws seems a must. In addition, the performance curves for the fluid movers is needed. The last need is accurate system field data. Systems effectively managed at the Chocolate Bayou plant were process air improvement, feed-water pressure reduction, combustion air blower turbine speed control, and cooling tower pressure reduction. Optimization of centrifugal systems is an often-overlooked opportunity for energy savings. The basic guidelines are to move only the fluid needed, and move it at as low a pressure as possible.

  14. Energy Savings for Centrifugal Compressors 

    E-print Network

    Fisher, D.

    2011-01-01

    Current design improvements of both the rotating and stationary aerodynamic components of centrifugal compressors can greatly increase the efficiency of vintage machines. A centrifugal compressor built in the 1970's or 1980's might have an external...

  15. Energy Savings for Centrifugal Compressors

    E-print Network

    Fisher, D.

    2011-01-01

    Current design improvements of both the rotating and stationary aerodynamic components of centrifugal compressors can greatly increase the efficiency of vintage machines. A centrifugal compressor built in the 1970's or 1980's might have an external...

  16. Enhancing Centrifugal Separation With Electrophoresis

    NASA Technical Reports Server (NTRS)

    Herrmann, F. T.

    1986-01-01

    Separation of biological cells by coil-planet centrifuge enhanced by electrophoresis. By itself, coil-planet centrifuge offers relatively gentle method of separating cells under low centrifugal force in physiological medium that keeps cells alive. With addition of voltage gradient to separation column of centrifuge, separation still gentle but faster and more complete. Since separation apparatus contains no rotary seal, probability of leakage, contamination, corrosion, and short circuits reduced.

  17. Next Generation Safeguards Initiative: Analysis of Probability of Detection of Plausible Diversion Scenarios at Gas Centrifuge Enrichment Plants Using Advanced Safeguards

    SciTech Connect

    Hase, Kevin R. [Los Alamos National Laboratory; Hawkins Erpenbeck, Heather [Los Alamos National Laboratory; Boyer, Brian D. [Los Alamos National Laboratory

    2012-07-10

    Over the last decade, efforts by the safeguards community, including inspectorates, governments, operators and owners of centrifuge facilities, have given rise to new possibilities for safeguards approaches in enrichment plants. Many of these efforts have involved development of new instrumentation to measure uranium mass and uranium-235 enrichment and inspection schemes using unannounced and random site inspections. We have chosen select diversion scenarios and put together a reasonable system of safeguards equipment and safeguards approaches and analyzed the effectiveness and efficiency of the proposed safeguards approach by predicting the probability of detection of diversion in the chosen safeguards approaches. We analyzed the effect of redundancy in instrumentation, cross verification of operator instrumentation by inspector instrumentation, and the effects of failures or anomalous readings on verification data. Armed with these esults we were able to quantify the technical cost benefit of the addition of certain instrument suites and show the promise of these new systems.

  18. 1. Theory for Heat Capacity of Ideal Gas I ) KDB correlation equation (HC_CPGEQN)

    E-print Network

    Hong, Deog Ki

    1. Theory for Heat Capacity of Ideal Gas I ) KDB correlation equation (HC_CPGEQN) Polynomial equation is used for Heat capacity of ideal gas. = = 4 0 0 )( i i ip TATC (1) where, T is Kelvin and )( 0 TCp is kJ/kg-mol.K. 2. KDB Routines for Calculation of Ideal Gas Heat Capacity KDB Ideal gas heat

  19. Lattice-gas model in kinetic theory of gas-solid interface processes

    NASA Astrophysics Data System (ADS)

    Tovbin, Yu. K.

    The improvement of the experimental methods for investigating surface processes changes the existing ideas about the role of the different factors of the gas-solid system and the mechanisms of the processes. The recent studies have confirmed the conception of surface processes as the ones taking place in the condensed phases. At the same time, the surface processes generally are described by fairly rough models based on the law of mass action, which is true of the ideal systems. The contradiction is eliminated to a certain degree when a lattice-gas model which takes into account the proper volume of the adspecies and adspecies interaction is used. On this basis it is easy to consider the effect of the local environment on the activation barrier of an elementary process. This enables one to apply it extensively to be the atomic-molecular processes associated with a change in the spatial arrangement of the adspecies and their chemical conversion. The review describes the development of the kinetic theory of the surface processes at the gas-solid interface using on the lattice-gas model and its modern modifications. Applications of the theory to the adsorption-desorption processes and the catalytic reactions are considered. The reaction rates in the condensed phases and the role of the correlation effects of the interacting adspecies and the distribution of the system's components are described. The lattice-gas model helps us explain the empirical principles of the adsorption processes; a variable order of desorption rate; the splitting of the thermodesorption spectra on the homogeneous surfaces; an increase in the sticking coefficient with coverage at its small values; phase transitions in the adlayers and their effect on the adsorption-desorption rate and the diffusion coefficients; a great mutual effect of the adspecies of the different kinds on the rate of the elementary processes; the dependence of the course of a process on the conditions in which the initial surface coverages are formed; multiplicity of the steady states of the reaction systems and the isothermal oscillation conditions of the reaction mode; etc. At present the theory of surface processes enables one to take into account a wide range of the real properties of the gas-solid system: the lateral interaction between the adspecies and their phase transitions, surface inhomogeneity, a limited mobility of the adspecies and the solid body surface atoms, the rearrangement of the subsurface solid region and so on. The joint influence of the factors mentioned above are also taken into account. Theoretical results are compared with the numerical calculations by the Monte Carlo methods.

  20. Centrifuge modelling of capillary rise

    Microsoft Academic Search

    N. Depountis; M. C. R. Davies; C. Harris; S. Burkhart; L. Thorel; A. Rezzoug; D. König; C. Merrifield; W. H. Craig

    2001-01-01

    This paper reports results from centrifuge tests designed to investigate capillary rise in soils subjected to different gravitational fields. The experimental programme is part of the EU-funded NECER project (Network of European Centrifuges for Environmental Geotechnic Research), whose objective is to investigate the appropriateness of geotechnical centrifuge modelling for the investigation of geoenvironmental problems, particularly with reference to partially saturated

  1. 3, 731768, 2006 Centrifuge modeling

    E-print Network

    Paris-Sud XI, Université de

    HESSD 3, 731­768, 2006 Centrifuge modeling of one-step tests H. Nakajima and A. T. Stadler Title are under open-access review for the journal Hydrology and Earth System Sciences Centrifuge modeling of one­768, 2006 Centrifuge modeling of one-step tests H. Nakajima and A. T. Stadler Title Page Abstract

  2. Subsychronous vibration of multistage centrifugal compressors forced by rotating stall

    NASA Technical Reports Server (NTRS)

    Fulton, J. W.

    1987-01-01

    A multistage centrifugal compressor, in natural gas re-injection service on an offshore petroleum production platform, experienced subsynchronous vibrations which caused excessive bearing wear. Field performance testing correlated the subsynchronous amplitude with the discharge flow coefficient, demonstrating the excitation to be aerodynamic. Adding two impellers allowed an increase in the diffuser flow angle (with respect to tangential) to meet the diffuser stability criteria based on factory and field tests correlated using the theory of Senoo (for rotating stall in a vaneless diffuser). This modification eliminated all significant subsynchronous vibrations in field service, thus confirming the correctness of the solution. Other possible sources of aerodynamically induced vibrations were considered, but the judgment that those are unlikely has been confirmed by subsequent experience with other similar compressors.

  3. Optimizing centrifugal pump operation

    Microsoft Academic Search

    Stan Shiels

    2001-01-01

    Centrifugal pump operation is more than switching the pump on and directing the discharge flow to the required delivery point. This holds true even when a control valve is installed in the discharge line for the purpose of flow or level control. A few very essential operating guidelines must be adhered to if early bearing or seal failure, premature erosion

  4. Immunoaffinity centrifugal precipitation chromatography

    Microsoft Academic Search

    Lin Qi; Yoichiro Ito

    2007-01-01

    Purification of proteins based on immunoaffinity has been performed using a solid support coated with antibody against the target proteins. The method requires immobilizing the antibody onto the solid support using protein A or G, and has a risk of adsorptive loss of target proteins onto the solid support. Centrifugal precipitation chromatography has been successfully used to purify enzymes, such

  5. Human Powered Centrifuge

    NASA Technical Reports Server (NTRS)

    Mulenburg, Gerald M. (Inventor); Vernikos, Joan (Inventor)

    1997-01-01

    A human powered centrifuge has independently established turntable angular velocity and human power input. A control system allows excess input power to be stored as electric energy in a battery or dissipated as heat through a resistors. In a mechanical embodiment, the excess power is dissipated in a friction brake.

  6. Design and prototyping of micro centrifugal compressor

    Microsoft Academic Search

    Shimpei Mizuki; Gaku Minorikawa; Toshiyuki Hirano; Yuichiro Asaga; Naoki Yamaguchi; Yutaka Ohta; Eisuke Outa

    2003-01-01

    In order to establish the design methodology of ultra micro centrifugal compressor, which is the most important component\\u000a of ultra micro gas turbine unit, a 10 times of the final target size model was designed, prototyped and tested. The problems\\u000a to be solved for downsizing were examined and 2-dimensional impeller was chosen as the first model due to its productivity.

  7. Unitary Fermi Gas, ? Expansion, and Nonrelativistic Conformal Field Theories

    NASA Astrophysics Data System (ADS)

    Nishida, Yusuke; Son, Dam Thanh

    We review theoretical aspects of unitary Fermi gas (UFG), which has been realized in ultracold atom experiments. We first introduce the ? expansion technique based on a systematic expansion in terms of the dimensionality of space. We apply this technique to compute the thermodynamic quantities, the quasiparticle cum, and the criticl temperature of UFG. We then discuss consequences of the scale and conformal invariance of UFG. We prove a correspondence between primary operators in nonrelativistic conformal field theories and energy eigenstates in a harmonic potential. We use this correspondence to compute energies of fermions at unitarity in a harmonic potential. The scale and conformal invariance together with the general coordinate invariance constrains the properties of UFG. We show the vanishing bulk viscosities of UFG and derive the low-energy effective Lagrangian for the superfluid UFG. Finally we propose other systems exhibiting the nonrelativistic scaling and conformal symmetries that can be in principle realized in ultracold atom experiments.

  8. Hot Gas in Galaxy Clusters: Theory and Simulations

    E-print Network

    Michael L. Norman

    2005-11-16

    We review the theory of the formation of galaxy clusters and discuss their role as cosmological probes. We begin with the standard cosmological framework where we discuss the origin of the CDM matter power spectrum and the growth of density fluctuations in the linear regime. We then summarize the spherical top-hat model for the nonlinear growth of fluctuations from which scaling relations and halo statistics are derived. Numerical methods for simulating gas in galaxy clusters are then overviewed with an emphasis on multiscale hydrodynamic simulations of cluster ensembles. Results of hydrodynamic AMR simulations are described which compare cluster internal and statistical properties as a function of their assumed baryonic processes. Finally, we compare various methods of measuring cluster masses using X-ray and the thermal Sunyaev-Zeldovich effect (SZE). We find that SZE offers great promise for precision measurements in raw samples of high-z clusters.

  9. Centrifugal unbalance detection system

    SciTech Connect

    Cordaro, Joseph V. (Martinez, GA); Reeves, George (Graniteville, SC); Mets, Michael (Aiken, SC)

    2002-01-01

    A system consisting of an accelerometer sensor attached to a centrifuge enclosure for sensing vibrations and outputting a signal in the form of a sine wave with an amplitude and frequency that is passed through a pre-amp to convert it to a voltage signal, a low pass filter for removing extraneous noise, an A/D converter and a processor and algorithm for operating on the signal, whereby the algorithm interprets the amplitude and frequency associated with the signal and once an amplitude threshold has been exceeded the algorithm begins to count cycles during a predetermined time period and if a given number of complete cycles exceeds the frequency threshold during the predetermined time period, the system shuts down the centrifuge.

  10. 77 FR 9273 - USEC Inc. (American Centrifuge Lead Cascade Facility and American Centrifuge Plant); Direct...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-02-16

    ...COMMISSION [NRC-2010-0355] USEC Inc. (American Centrifuge Lead Cascade Facility and American Centrifuge Plant); Direct Transfer of Licenses In the Matter of USEC INC. (American Centrifuge Lead Cascade Facility and American Centrifuge...

  11. Centrifugal Filter Devices Centricon centrifugal filter devices with 10,000 NMWL, 30,000 NMWL,

    E-print Network

    Kirschner, Marc W.

    CENTRICON ® Centrifugal Filter Devices User Guide Centricon centrifugal filter devices with 10-vitro diagnostic use. Centricon centrifugal filter devices with 3,000 NMWL Ultracel YM membranes are for research ................................................... 3 Maximum Centrifugal Force .............................................................. 3 Rotor

  12. The Magnetic Centrifugal Mass Filter

    SciTech Connect

    Abraham J. Fetterman and Nathaniel J. Fisch

    2011-08-04

    Mass filters using rotating plasmas have been considered for separating nuclear waste and spent nuclear fuel. We propose a new mass filter that utilizes centrifugal and magnetic confinement of ions in a way similar to the asymmetric centrifugal trap. This magnetic centrifugal mass filter is shown to be more proliferation resistant than present technology. This filter is collisional and produces well confined output streams, among other advantages. __________________________________________________

  13. Centrifuge impact cratering experiment 5

    NASA Technical Reports Server (NTRS)

    1984-01-01

    Transient crates motions, cratering flow fields, crates dynamics, determining impact conditions from total crater welt, centrifuge quarter-space cratering, and impact cratering mechanics research is documented.

  14. CENTRIFUGAL MEMBRANE FILTRATION

    SciTech Connect

    Daniel J. Stepan; Bradley G. Stevens; Melanie D. Hetland

    1999-10-01

    The overall project consists of several integrated research phases related to the applicability, continued development, demonstration, and commercialization of the SpinTek centrifugal membrane filtration process. Work performed during this reporting period consisted of Phase 2 evaluation of the SpinTek centrifugal membrane filtration technology and Phase 3, Technology Partnering. During Phase 1 testing conducted at the EERC using the SpinTek ST-IIL unit operating on a surrogate tank waste, a solids cake developed on the membrane surface. The solids cake was observed where linear membrane velocities were less than 17.5 ft/s and reduced the unobstructed membrane surface area up to 25%, reducing overall filtration performance. The primary goal of the Phase 2 research effort was to enhance filtration performance through the development and testing of alternative turbulence promoter designs. The turbulence promoters were designed to generate a shear force across the entire membrane surface sufficient to maintain a self-cleaning membrane capability and improve filtration efficiency and long-term performance. Specific Phase 2 research activities included the following: System modifications to accommodate an 11-in.-diameter, two-disk rotating membrane assembly; Development and fabrication of alternative turbulence promoter designs; Testing and evaluation of the existing and alternative turbulence promoters under selected operating conditions using a statistically designed test matrix; and Data reduction and analysis; The objective of Phase 3 research was to demonstrate the effectiveness of SpinTek's centrifugal membrane filtration as a pretreatment to remove suspended solids from a liquid waste upstream of 3M's WWL cartridge technology for the selective removal of technetium (Tc).

  15. Centrifuges Replacement Study Proposal

    E-print Network

    Iqbal, Muhammad

    2005-12-16

    . 6 1.3 Facsimile of Bayer?s nameplate or equipment tag and manufacturer's nameplate. Photocopies preferred, pencil rubbings acceptable. 6 1.4 1.5 1.6 Notes: 1. Data with quotation must be representative, if not exact, to define....9.1.3 Thermal Feed Controller System temperature Meets all requirements 3.9.1.4 Safety Door Lock solenoid (24VDC coil) Meets all requirements 3.9.1.5 Vibration Transducer and cable for termination in centrifuge field junction box. Meets all requirements 3...

  16. 21 CFR 864.5350 - Microsedimentation centrifuge.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ...2011-04-01 false Microsedimentation centrifuge. 864.5350 Section 864.5350... § 864.5350 Microsedimentation centrifuge. (a) Identification. A microsedimentation centrifuge is a device used to sediment red...

  17. 21 CFR 864.5350 - Microsedimentation centrifuge.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ...2010-04-01 false Microsedimentation centrifuge. 864.5350 Section 864.5350... § 864.5350 Microsedimentation centrifuge. (a) Identification. A microsedimentation centrifuge is a device used to sediment red...

  18. Centrifugal shot blast system

    SciTech Connect

    NONE

    1998-02-01

    This report describes a demonstration of Concrete cleaning, Inc., modified centrifugal shot blast technology to remove the paint coating from concrete flooring. This demonstration is part of the Chicago Pile-5 (CP-5) Large-Scale Demonstration Project (LSDP) sponsored by the US Department of Energy (DOE), office of Science and Technology (OST), Deactivation and Decommissioning Focus Area (DDFA). The objective of the LSDP is to select and demonstrate potentially beneficial technologies at the Argonne National Laboratory-East (ANL) CP-5 Research Reactor. The purpose of the LSDP is to demonstrate that using innovative and improved decontamination and decommissioning (D and D) technologies from various sources can result in significant benefits, such as decreased cost and increased health and safety, as compared with baseline D and D technologies. Potential markets exist for the innovative centrifugal shot blast system at the following sites: Fernald Environmental Management Project, Los Alamos, Nevada, Oak Ridge Y-12 and K-25, Paducah, Portsmouth Gaseous Diffusion site, and the Savannah River Site. This information is based on a revision to the OST Linkage Tables dated August 4, 1997.

  19. Central centrifugal cicatricial alopecia.

    PubMed

    Whiting, David A; Olsen, Elise A

    2008-01-01

    A progressive scarring alopecia of the central scalp is commonly seen in young to middle-aged females of African descent. It usually starts at the vertex or mid top of the scalp and gradually spreads centrifugally, hence, the unifying term of central centrifugal cicatricial alopecia. The clinical pattern is suggestive of female pattern alopecia, but a lack of follicular pores indicative of scarring is present. It can progress for years before slowly burning out. The etiology is unknown but genetic factors may be important. It is often associated with a history of traumatic hairstyling involving heat, traction, and chemicals. However, most patients of African descent without this disorder have similar styling habits. Nonetheless, avoidance of physical and chemical trauma to the scalp hair, the use of suitable shampoos and conditioners, and the encouragement of natural hairstyles may be helpful. Any infection should be treated. Topical or intralesional corticosteroids and systemic antibiotics may be useful and topical minoxidil should be tried with the hope of preventing further scarring and encouraging regrowth of recovering follicles. Current research into the etiology of this disorder will help to foster much-needed clinical trials of therapeutic agents. PMID:18715297

  20. Centrifuge treatment of coal tar

    SciTech Connect

    L.A. Kazak; V.Z. Kaidalov; L.F. Syrova; O.S. Miroshnichenko; A.S. Minakov [Giprokoks, the State Institute for the Design of Coke-Industry Enterprises, Kharkov (Ukraine)

    2009-07-15

    New technology is required for the removal of water and heavy fractions from regular coal tar. Centrifuges offer the best option. Purification of coal tar by means of centrifuges at OAO NLMK permits the production of pitch coke or electrode pitch that complies with current standards.

  1. Rat growth during chronic centrifugation

    NASA Technical Reports Server (NTRS)

    Pitts, G. C.; Oyama, J.

    1978-01-01

    Female weanling rats were chronically centrifuged at 4.15 G with controls at terrestrial gravity. Samples were sacrificed for body composition studies at 0, 28, 63, 105 and 308 days of centrifugation. The centrifuged group approached a significantly lower mature body mass than the controls (251 and 318g) but the rate of approach was the same in both groups. Retirement to 1G on the 60th day resulted in complete recovery. Among individual components muscle, bone, skin, CNS, heart, kidneys, body water and body fat were changed in the centrifuged group. However, an analysis of the growth of individual components relative to growth of the total fat-free compartment revealed that only skin (which increased in mass) was responding to centrifugation per se.

  2. Unshrouded Centrifugal Turbopump Impeller

    NASA Technical Reports Server (NTRS)

    Prueger, George; Williams, Morgan; Chen, Wei; Paris, John; Stewart, Eric; Williams, Robert

    1999-01-01

    The ratio of rocket engine thrust to weight is a limiting constraint in placing more payload into orbit at a low cost. A key component of an engine's overall weight is the turbopump weight, Reducing the turbopump weight can result in significant engine weight reduction and hence, increased delivered payload. There are two main types of pumps: centrifugal and axial pumps. These types of pumps can be further sub-divided into those with shrouds and those without shrouds (unshrouded pumps). Centrifugal pumps can achieve the same pump discharge pressure as an axial pump and it requires fewer pump stages and lower pump weight than an axial pump. Also, with unshrouded centrifugal pumps (impeller), the number of stages and weight can be further reduced. However. there are several issues with regard to using an unshrouded impeller: 1) there is a pump performance penalty due to the front open face recirculation flow; 2) there is a potential pump axial thrust problem from the unbalanced front open face and the back shroud face; and, 3) since test data is very linu'ted for this configuration, there is uncertainty in the magnitude and phase of the rotordynamics forces due to the front impeller passage. The purpose of the paper is to discuss the design of an unshrouded impeller and to examine the design's hydrodynamic performance, axial thrust, and rotordynamics performance. The design methodology will also be discussed. This work will help provide some guidelines for unshrouded impeller design. In particular, the paper will discuss the design of three unshrouded impellers - one with 5 full and 5 partial blades (5+5). one with 6+6 blades and one with 8+8 blades. One of these designs will be selected for actual fabrication and flow test. Computational fluid dynamics (CFD) is used to help design and optimize the unshrouded impeller. The relative pump performance penalty is assessed by comparing the CFD results of the unshrouded impeller with the equivalent shrouded impeller for a particular design. Limited unshrouded - versus - shrouded impeller data from the J-2 pump is used to anchor the CFD. Since no detailed impeller blade force data is available, axial thrust and rotordynamic force predictions are based on the CFD model. For the axial thrust, the impeller front flow passage axial force is integrated from the CFD results and compared to the equivalent shrouded impeller axial force. For the rotordynamics forces, the fluid reaction forces are computed from unsteady flow CFD results using a moving boundary method; the rotor- shaft is moved at several whirl-to-speed frequency ratios to extract the rotordynamics coefficients.

  3. Centrifugal mud mixer

    SciTech Connect

    Day, R.W.

    1980-01-22

    An apparatus and method for mixing liquid or drilling mud with solids are disclosed. The apparatus provides first and second concentric housings which are utilized as mixing chambers. An inlet passageway is tangentially connected to the inner housing for feeding a slurry material to be mixed with solids axially fed into the same housing. A discharge port is further provided and connected to an outer housing for tangentially discharging the homogeneous mixture of slurry and solid materials from the outer mixing chamber at high velocities to an elevation above the inlet. The method for mixing includes tangentially feeding the slurry into the mixing chamber, mixing the slurry with solid materials through the use of centrifugal force, shear forces and spill-over from the inner chamber to the outer chamber, and finally tangentially discharging the mixture from the outer chamber.

  4. Centrifuge rotor integrated analysis

    NASA Astrophysics Data System (ADS)

    Ohtomi, Koichi; Kanzawa, Takuya; Hampton, Roy; Kawamoto, Osamu

    2004-09-01

    The Centrifuge Rotor (CR) is a large life science experiment facility which will be installed in the International Space Station (ISS). It will provide artificial gravity of 2g or less by rotating up to 4 science habitats, and it will be the first such machinery to be used in space. To prevent vibration disturbance exchanges between the CR and the ISS, a soft 5 dof vibration isolation mechanism is used which cannot support the CR weight on the ground. Therefore, the CR on-orbit performance must be predicted by integrated analysis which must model all of the equipment including sensors, actuators, flexible structure, gyroscopic effects, and controllers. Here, we introduce the CR mechatronics, a verification procedure, and examples of the application of the integrated analysis which is based on the general-purpose mechanism analysis software ADAMS.

  5. Design and prototyping of micro centrifugal compressor

    NASA Astrophysics Data System (ADS)

    Mizuki, Shimpei; Minorikawa, Gaku; Hirano, Toshiyuki; Asaga, Yuichiro; Yamaguchi, Naoki; Ohta, Yutaka; Outa, Eisuke

    2003-02-01

    In order to establish the design methodology of ultra micro centrifugal compressor, which is the most important component of ultra micro gas turbine unit, a 10 times of the final target size model was designed, prototyped and tested. The problems to be solved for downsizing were examined and 2-dimensional impeller was chosen as the first model due to its productivity. The conventional 1D prediction method, CFD and the inverse design were attempted. The prototyped compressor was driven by using a turbocharger and the performance characteristics were measured.

  6. Immunoaffinity centrifugal precipitation chromatography.

    PubMed

    Qi, Lin; Ito, Yoichiro

    2007-06-01

    Purification of proteins based on immunoaffinity has been performed using a solid support coated with antibody against the target proteins. The method requires immobilizing the antibody onto the solid support using protein A or G, and has a risk of adsorptive loss of target proteins onto the solid support. Centrifugal precipitation chromatography has been successfully used to purify enzymes, such as ketosteroid isomerase and hyaluronidase without the use of solid support. The purpose of this study is to demonstrate that immunoaffinity centrifugal precipitation chromatography is capable of isolating an antigen by exploiting antigen-antibody binding. The separation was initiated by filling both channels with 40% saturated ammonium sulfate (AS) of pH 4-4.5 followed by loading 20 microl of human plasma (National Institutes of Health blood bank) mixed with 2 mg of rabbit anti-HSA (human serum protein) antibody (Sigma). Then, the sample channel was eluted with water at 0.03 ml/min and AS channel with 40% AS solution of pH 4-4.5 at 1 ml/min until all non-binding components were eluted. Then, the releasing reagent (50% AS solution containing 0.5 M glycine and 10% ammonium hydroxide at pH 10) was introduced through the AS channel to release the target protein (HSA). The retained antibody was recovered by eluting the sample channel with water at 1 ml/min. A hollow fiber membrane device at the outlet (MicroKros, Spectrum, New Brunswick, NJ, USA) was provided on-line dialysis of the eluent before fractions were collected, so that the fractions could be analyzed by SDS-PAGE (sodium dodecyl sulfate - polyacrylamide gel electrophoresis) without further dialysis. The current method does not require immobilizing the antibody onto a matrix, which is used by the conventional immunoaffinity chromatography. This method ensures full recovery of the antigen and antibody, and it may be applied to purification of other proteins. PMID:17416378

  7. The Theory of a Free Jet of a Compressible Gas

    NASA Technical Reports Server (NTRS)

    Abramovich, G. N.

    1944-01-01

    In the present report the theory of free turbulence propagation and the boundary layer theory are developed for a plane-parallel free stream of a compressible fluid. In constructing the theory use was made of the turbulence hypothesis by Taylor (transport of vorticity) which gives best agreement with test results for problems involving heat transfer in free jets.

  8. Continuum approach to phonon gas and shape changes of second sound via shock waves theory

    Microsoft Academic Search

    T. Ruggeri; A. Muracchini; L. Seccia

    1994-01-01

    Summary  A continuum approach, based on the principles of modern extended thermodynamics, describing the model of a phonon gas is performed.\\u000a The main difference with the ideal phonon gas theory consists in the presence of athermal inertia. We apply the shock wave theory and discuss the selection rules for physical shocks (theLax conditions and theentropy growth). In this way the existence

  9. Galactic evolution. I - Single-zone models. [encompassing stellar evolution and gas-star dynamic theories

    NASA Technical Reports Server (NTRS)

    Thuan, T. X.; Hart, M. H.; Ostriker, J. P.

    1975-01-01

    The two basic approaches of physical theory required to calculate the evolution of a galactic system are considered, taking into account stellar evolution theory and the dynamics of a gas-star system. Attention is given to intrinsic (stellar) physics, extrinsic (dynamical) physics, and computations concerning the fractionation of an initial mass of gas into stars. The characteristics of a 'standard' model and its variants are discussed along with the results obtained with the aid of these models.

  10. Gas adsorption isotherm equation based on vacancy solution theory

    Microsoft Academic Search

    Solot Suwanayuen; Ronald P. Danner

    1980-01-01

    Pennsylvania State University's new isotherm equation for pure gas adsorption treats the adsorption equilbrium as an osmotic equilibrium between two ''vacancy'' solutions having different compositions. One solution represents the gas phase and the other the adsorbed phase. The vacancy solution is composed of adsorbates and vacancies (imaginary entities defined as the vacuum space that acts as the solvent for the

  11. Theory for a gas composition sensor based on acoustic properties

    Microsoft Academic Search

    Scott Phillips; Yefim Dain; Richard M. Lueptow

    2003-01-01

    Sound travelling through a gas propagates at different speeds and its intensity attenuates to different degrees depending upon the composition of the gas. Theoretically, a real-time gaseous composition sensor could be based on measuring the sound speed and the acoustic attenuation. To this end, the speed of sound was modelled using standard relations, and the acoustic attenuation was modelled using

  12. Experimental characterization of high speed centrifugal compressor aerodynamic forcing functions

    Microsoft Academic Search

    Kirk Gallier

    2005-01-01

    The most common and costly unexpected post-development gas turbine engine reliability issue is blade failure due to High Cycle Fatigue (HCF). HCF in centrifugal compressors is a coupled nonlinear fluid-structure problem for which understanding of the phenomenological root causes is incomplete. The complex physics of this problem provides significant challenges for Computational Fluid Dynamics (CFD) techniques. Furthermore, the available literature

  13. Developments in centrifugal compressor surge control: A technology assessment

    Microsoft Academic Search

    K. K. Botros; J. F. Henderson

    1994-01-01

    There are a number of surge control schemes in current use for centrifugal compressors employed in natural gas transmission systems. Basically, these schemes consist of a set of detection devices that either anticipate surge or detect it at its inception, and a set of control devices that act to prevent surge from occurring. A patent search was conducted in an

  14. TORSIONAL VIBRATION REDUCTION IN INTERNAL COMBUSTION ENGINES USING CENTRIFUGAL PENDULUMS

    Microsoft Academic Search

    Cheng-Tang Lee; Steven W. Shaw

    The goal of the present work is to investigate the performance of tautochronic centrifugal pendulum vibration absorbers (CPVA's) for reducing torsional vibration in internal combustion engines. A mathematical model is first built for the torsional dynamics of an in- line, four-stroke, four-cylinder engine, including the consideration of inertia effects of connecting rods and pistons, gas pressure inside the cylinder chambers,

  15. Thermal creep of a rarefied gas on the basis of non-linear Korteweg-theory

    E-print Network

    Kim, Yong Jung

    Thermal creep of a rarefied gas on the basis of non-linear Korteweg-theory Yong-Jung Kim1, Mingi to the memory of James B. Serrin Abstract. The study of thermal transpiration or more commonly called thermal of ordinary differential equations. Key words. thermal creep, thermal transpiration, rarefied gas, Boltz- mann

  16. Application of Data Fusion Theory in Coal Gas Fire Prediction System

    Microsoft Academic Search

    Xian-Min Ma

    2008-01-01

    In the coal mining production, the fire catastrophe is very dangerous to mining worker life and the whole coal well when the gas explosion is happening. So it is very important to predict fire happening and emit the alarm. In this paper, a novel coal gas fire prediction system is proposed based on multi-sensor data fusion theory. The four different

  17. Centrifugation. Sludge Treatment and Disposal Course #166. Instructor's Guide [and] Student Workbook.

    ERIC Educational Resources Information Center

    Best, Richard A.

    An introductory description of the use of centrifuges in the process of volume reduction is provided in this lesson. Three basic centrifuges, their theory of operation, quality of cake and centrate, and operational control testing are discussed. The lesson includes an instructor's guide and student workbook. The instructor's guide contains a…

  18. An Attack on Centrifugal Costs

    E-print Network

    Murray, P. F.

    AN ATTACK ON CENTRIFUGAL COSTS j P. ~,t~~c1ier Mwra~ I Mons'anto ' Alvin, 'ie~as I ABSTRACT Energy conservation in small and medium horse power industrial centrifugal power users has re ceived very little attention to date. Monsanto... the necessary audit of plant centrifugal systems. Primarily, the task force will review applications of 50 to 1500 HP. This paper will discuss some of the technology that has been used by this task force in several successful innovative conservation...

  19. APPLICATION OF CENTRIFUGE MODELING IN GEOTECHNICAL ENGINEERING

    E-print Network

    Kamat, Vineet R.

    APPLICATION OF CENTRIFUGE MODELING IN GEOTECHNICAL ENGINEERING Dr. Liming Li Manager of Centrifuge, Dec 5, 2012 4:00 PM GG Brown 2355 ABSTRACT: This seminar addresses the application of centrifuge may be obtained by substituting a centrifugal force to form the gravitational field, i.e., placing

  20. Centrifugal dryers keep pace with the market

    SciTech Connect

    Fiscor, S.

    2008-03-15

    New plant design and upgrades create a shift in dewatering strategies. The article describes recent developments. Three major manufacturers supply centrifugal dryers - TEMA, Centrifugal & Mechanical Industries (CMI) and Ludowici. CMI introduced a line of vertical centrifugal dryers. TEMA improved the techniques by developing a horizontal vibratory centrifuge (HVC) which simplified maintenance. 3 figs., 1 photo.

  1. Microwave assisted centrifuge and related methods

    DOEpatents

    Meikrantz, David H. (Idaho Falls, ID) [Idaho Falls, ID

    2010-08-17

    Centrifuge samples may be exposed to microwave energy to heat the samples during centrifugation and to promote separation of the different components or constituents of the samples using a centrifuge device configured for generating microwave energy and directing the microwave energy at a sample located in the centrifuge.

  2. Bubble Eliminator Based on Centrifugal Flow

    NASA Technical Reports Server (NTRS)

    Gonda, Steve R.; Tsao, Yow-Min D.; Lee, Wenshan

    2004-01-01

    The fluid bubble eliminator (FBE) is a device that removes gas bubbles from a flowing liquid. The FBE contains no moving parts and does not require any power input beyond that needed to pump the liquid. In the FBE, the buoyant force for separating the gas from the liquid is provided by a radial pressure gradient associated with a centrifugal flow of the liquid and any entrained bubbles. A device based on a similar principle is described in Centrifugal Adsorption Cartridge System (MSC- 22863), which appears on page 48 of this issue. The FBE was originally intended for use in filtering bubbles out of a liquid flowing relatively slowly in a bioreactor system in microgravity. Versions that operate in normal Earth gravitation at greater flow speeds may also be feasible. The FBE (see figure) is constructed as a cartridge that includes two concentric cylinders with flanges at the ends. The outer cylinder is an impermeable housing; the inner cylinder comprises a gas-permeable, liquid-impermeable membrane covering a perforated inner tube. Multiple spiral disks that collectively constitute a spiral ramp are mounted in the space between the inner and outer cylinders. The liquid enters the FBE through an end flange, flows in the annular space between the cylinders, and leaves through the opposite end flange. The spiral disks channel the liquid into a spiral flow, the circumferential component of which gives rise to the desired centrifugal effect. The resulting radial pressure gradient forces the bubbles radially inward; that is, toward the inner cylinder. At the inner cylinder, the gas-permeable, liquid-impermeable membrane allows the bubbles to enter the perforated inner tube while keeping the liquid in the space between the inner and outer cylinders. The gas thus collected can be vented via an endflange connection to the inner tube. The centripetal acceleration (and thus the radial pressure gradient) is approximately proportional to the square of the flow speed and approximately inversely proportional to an effective radius of the annular space. For a given FBE geometry, one could increase the maximum rate at which gas could be removed by increasing the rate of flow to obtain more centripetal acceleration. In experiments and calculations oriented toward the original microgravitational application, centripetal accelerations between 0.001 and 0.012 g [where g normal Earth gravitation (.9.8 m/s2)] were considered. For operation in normal Earth gravitation, it would likely be necessary to choose the FBE geometry and the rate of flow to obtain centripetal acceleration comparable to or greater than g.

  3. Numerical Navier-Stokes Solutions from Gas Kinetic Theory

    Microsoft Academic Search

    Kun Xu; Kevin H. Prendergast

    1994-01-01

    In order to test the gas-kinetic based hydrodynamic scheme given in paper I (K. H. Prendergast and K. Xu, J. Comput. Phys.109, 53, 1993) as a Navier-Stokes solver, we extend the scheme to two dimensions and exhibit some Navier-Stokes solutions. The scheme is a high-resolution gas kinetic scheme in both space and time. The advective and diffusive fluxes are coupled

  4. Centrifugation during the Manhattan Project

    Microsoft Academic Search

    B. Cameron Reed

    2009-01-01

    Manhattan Engineer District documents from 1942 to early 1944 reveal that consideration of centrifugation as a means of enriching\\u000a uranium-235 during World War II was more extensive than is commonly appreciated. A full-scale prototype centrifuge was fabricated\\u000a and tested at near-production speeds; enrichments at close to levels expected theoretically was demonstrated with pilot-plant\\u000a units; and plans for production plants were

  5. Variable-Speed Instrumented Centrifuges

    NASA Technical Reports Server (NTRS)

    Chapman, David K.; Brown, Allan H.

    1991-01-01

    Report describes conceptual pair of centrifuges, speed of which varied to produce range of artificial gravities in zero-gravity environment. Image and data recording and controlled temperature and gravity provided for 12 experiments. Microprocessor-controlled centrifuges include video cameras to record stop-motion images of experiments. Potential applications include studies of effect of gravity on growth and on production of hormones in corn seedlings, experiments with magnetic flotation to separate cells, and electrophoresis to separate large fragments of deoxyribonucleic acid.

  6. Physiologia Plantarum 140: 311320. 2010 Copyright Physiologia Plantarum 2010, ISSN 0031-9317 What happens when stems are embolized in a centrifuge?

    E-print Network

    Hacke, Uwe

    -9317 What happens when stems are embolized in a centrifuge? Testing the cavitron theory Jing Caia,b, Uwe of stems. The fastest method of measuring VCs is the centrifuge technique and the Cochard cavitron in a centrifuge ought to differ from the pattern during natural dehydration of plants because the profiles

  7. Membrane-based characterization of a gas component--a transient sensor theory.

    PubMed

    Lazik, Detlef

    2014-01-01

    Based on a multi-gas solution-diffusion problem for a dense symmetrical membrane this paper presents a transient theory of a planar, membrane-based sensor cell for measuring gas from both initial conditions: dynamic and thermodynamic equilibrium. Using this theory, the ranges for which previously developed, simpler approaches are valid will be discussed; these approaches are of vital interest for membrane-based gas sensor applications. Finally, a new theoretical approach is introduced to identify varying gas components by arranging sensor cell pairs resulting in a concentration independent gas-specific critical time. Literature data for the N2, O2, Ar, CH4, CO2, H2 and C4H10 diffusion coefficients and solubilities for a polydimethylsiloxane membrane were used to simulate gas specific sensor responses. The results demonstrate the influence of (i) the operational mode; (ii) sensor geometry and (iii) gas matrices (air, Ar) on that critical time. Based on the developed theory the case-specific suitable membrane materials can be determined and both operation and design options for these sensors can be optimized for individual applications. The results of mixing experiments for different gases (O2, CO2) in a gas matrix of air confirmed the theoretical predictions. PMID:24608004

  8. Membrane-Based Characterization of a Gas Component — A Transient Sensor Theory

    PubMed Central

    Lazik, Detlef

    2014-01-01

    Based on a multi-gas solution-diffusion problem for a dense symmetrical membrane this paper presents a transient theory of a planar, membrane-based sensor cell for measuring gas from both initial conditions: dynamic and thermodynamic equilibrium. Using this theory, the ranges for which previously developed, simpler approaches are valid will be discussed; these approaches are of vital interest for membrane-based gas sensor applications. Finally, a new theoretical approach is introduced to identify varying gas components by arranging sensor cell pairs resulting in a concentration independent gas-specific critical time. Literature data for the N2, O2, Ar, CH4, CO2, H2 and C4H10 diffusion coefficients and solubilities for a polydimethylsiloxane membrane were used to simulate gas specific sensor responses. The results demonstrate the influence of (i) the operational mode; (ii) sensor geometry and (iii) gas matrices (air, Ar) on that critical time. Based on the developed theory the case-specific suitable membrane materials can be determined and both operation and design options for these sensors can be optimized for individual applications. The results of mixing experiments for different gases (O2, CO2) in a gas matrix of air confirmed the theoretical predictions. PMID:24608004

  9. THEORY OF A QUODON GAS WITH APPLICATION TO PRECIPITATION KINETICS IN SOLIDS UNDER IRRADIATION

    SciTech Connect

    Dubinko, Volodymyr; Shapovalov, Roman V.

    2014-06-17

    Rate theory of the radiation-induced precipitation in solids is modified with account of non-equilibrium fluctuations driven by the “gas” of lattice solitons (a.k.a. “quodons”) produced by irradiation. According to quantitative estimations, a steady-state density of the quodon gas under sufficiently intense irradiation can be comparable to the density of classical phonon gas. The modified rate theory is applied to modelling of copper precipitation in FeCu binary alloys under electron irradiation. In contrast to the classical rate theory, which disagrees strongly with experimental data on all precipitation parameters, the modified rate theory describes quite well both the evolution of precipitates and the matrix concentration of copper measured by different methods.

  10. 76 FR 9613 - USEC Inc. (American Centrifuge Lead Cascade Facility and American Centrifuge Plant); Order...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-02-18

    ...EA-11-013] USEC Inc. (American Centrifuge Lead Cascade Facility and American Centrifuge Plant); Order Approving Direct Transfer...7003 and SNM-2011 for the American Centrifuge Lead Cascade Facility (Lead...

  11. 75 FR 70300 - USEC, Inc.; American Centrifuge Lead Cascade Facility; American Centrifuge Plant; Notice of...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-11-17

    ...NRC-2010-0355] USEC, Inc.; American Centrifuge Lead Cascade Facility; American Centrifuge Plant; Notice of Receipt of a License Transfer...SNM-7003 and SNM-2011, for the American Centrifuge Lead Cascade Facility and the American...

  12. Fluid forces on rotating centrifugal impeller with whirling motion

    NASA Technical Reports Server (NTRS)

    Shoji, H.; Ohashi, H.

    1980-01-01

    Fluid forces on a centrifugal impeller, whose rotating axis whirls with a constant speed, were calculated by using unsteady potential theory. Calculations were performed for various values of whirl speed, number of impeller blades and angle of blades. Specific examples as well as significant results are given.

  13. Density wave theory. [interstellar gas dynamics and galactic shock waves

    NASA Technical Reports Server (NTRS)

    Roberts, W. W., Jr.

    1977-01-01

    The prospect that density waves and galactic shock waves are present on the large scale in disk shaped galaxies has received support in recent years from both theoretical and observational studies. Large-scale galactic shock waves in the interstellar gas are suggested to play an important governing role in star formation, molecule formation, and the degree of development of spiral structure. Through the dynamics of the interstellar gas and the galactic shock-wave phenomenon, a new insight into the physical basis underlying the morphological classification system of galaxies is suggested.

  14. Hyperbolically shaped centrifugal compressor

    NASA Astrophysics Data System (ADS)

    Puzyrewski, Romuald; Flaszy?ski, Pawel

    2003-08-01

    Starting from the classical centrifugal compressor, cone shaped in meridional cross section, two modifications are considered on the basis of results from 2D and 3D flow models. The first modification is the change of the meridional cross section to hyperbolically shaped channel. The second modification, proposed on the basis of 2D axisymmetric solution, concerns the shape of blading. On the strength of this solution the blades are formed as 3D shaped blades, coinciding with the recent tendency in 3D designs. Two aims were considered for the change of meridional compressor shape. The first was to remove the separation zone which appears as the flow turns from axial to radial direction. The second aim is to uniformize the flow at exit of impeller. These two goals were considered within the frame of 2D axisymmetric model. Replacing the cone shaped compressor by a hyperbolically shaped one, the separation at the corner was removed. The disc and shroud shape of the compressor was chosen in the way which satisfies the condition of most uniform flow at the compressor exit. The uniformity of exit flow from the rotor can be considered as the factor which influences the performance of the diffuser following the rotor. In the 2D model a family of stream surfaces of S 1 type is given in order to find S 2 surfaces which may be identified with the midblade surfaces of compressor blading. A computation of 3D type has been performed in order to establish the relations between 2D and 3D models in the calculation of flow parameters. In the presented example the 2D model appears as the inverse model which leads to 3D shape of blading whereas the 3D model has been used for the direct solution. In the presented example the confrontation of two models, 2D and 3D, leads to a better understanding of the application of these models to the design procedure.

  15. Effect of centrifugal force on critical flutter speed on a uniform cantilever beam

    NASA Technical Reports Server (NTRS)

    Mendelson, Alexander

    1948-01-01

    Semirigid flutter theory is used. Calculations are made on airfoils with fundamental bending frequencies up to 2000 radian per second. Centrifugal force can under certain conditions reduce the critical flutter speed.

  16. Investigation of surge behavior in a micro centrifugal compressor

    NASA Astrophysics Data System (ADS)

    Mizuki, Shimpei; Asaga, Yuichiro; Ono, Yushi; Tsujita, Hoshio

    2006-06-01

    This paper reports the experimental and theoretical study of the surge occurred in prototyping an ultra micro centrifugal compressor. As the first step, the 10 times size model of an ultra micro centrifugal compressor having the 40 mm outer diameter was designed and manufactured. The detailed experimental investigations for the transient behavior of surge with several different values of B parameter were carried out. The experimental results during the surge were compared with those obtained by the non-linear lumped parameter theory in order to validate the effectiveness of the theoretical surge model for the micro centrifugal compressor. As a result, the quite different behavior of the surge appeared for the different values of B both in the experiment and in the analysis.

  17. Centrifuge-Based Fluidic Platforms

    NASA Astrophysics Data System (ADS)

    Zoval, Jim; Jia, Guangyao; Kido, Horacio; Kim, Jitae; Kim, Nahui; Madou, Marc

    In this chapter centrifuge-based microfluidic platforms are reviewed and compared with other popular microfluidic propulsion methods. The underlying physical principles of centrifugal pumping in microfluidic systems are presented and the various centrifuge fluidic functions such as valving, decanting, calibration, mixing, metering, heating, sample splitting, and separation are introduced. Those fluidic functions have been combined with analytical measurements techniques such as optical imaging, absorbance and fluorescence spectroscopy and mass spectrometry to make the centrifugal platform a powerful solution for medical and clinical diagnostics and high-throughput screening (HTS) in drug discovery. Applications of a compact disc (CD)-based centrifuge platform analyzed in this review include: two-point calibration of an optode-based ion sensor, an automated immunoassay platform, multiple parallel screening assays and cellular-based assays. The use of modified commercial CD drives for high-resolution optical imaging is discussed as well. From a broader perspective, we compare the technical barriers involved in applying microfluidics for sensing and diagnostic as opposed to applying such techniques to HTS. The latter poses less challenges and explains why HTS products based on a CD fluidic platform are already commercially available, while we might have to wait longer to see commercial CD-based diagnostics.

  18. Sedimentation of a suspension in a centrifugal field.

    PubMed

    Lueptow, R M; Hübler, W

    1991-11-01

    To model centrifugal sedimentation of biological suspensions, the time history of sedimentation of particles in a centrifugal field was considered for two geometries: a tube and a cylindrical container. The Kynch theory for batch gravitational settling in Cartesian coordinates based on mass conservation was extended to include a centrifugal sedimentation force, cylindrical coordinates, and the Hawksley-Vand hindered settling model. The resulting quasi-linear partial differential equation was solved by the method of characteristics. The combination of radial dependence of the sedimentation force and cylindrical geometry in the centrifugal case results in several differences in the time-position history diagram of the sedimentation process compared to the gravitational case. First, instead of a region of uniform concentration equal to the initial concentration, a region of concentration that is continuously decreasing with time results. Second, in the region of particle accumulation, curved constant concentration contours result instead of straight lines. Finally, a secondary shock that is dependent upon the initial concentration and the radius ratio of the rotating vessel appears in the centrifugal case. The time history of the concentration for a particle suspension with an initial concentration typical of blood is presented. PMID:1762447

  19. Performance prediction of centrifugal pumps and compressors; Proceedings of the Twenty-fifth Annual International Gas Turbine Conference and Exhibit and Twenty-second Annual Fluids Engineering Conference, New Orleans, La., March 9-13, 1980

    Microsoft Academic Search

    S. Gopalakrishnan; P. Cooper; C. Grennan; J. Switzer

    1979-01-01

    Comparison of multi-dimensional flow analysis with experimental data is considered. Detailed flow field investigations are presented and combined inviscid flow and loss analysis is discussed. Performance prediction of centrifugal compressors and pumps is analyzed along with prediction of other performance-related phenomena.

  20. Hydrodynamic simulation of gas–solid flow in a riser using kinetic theory of granular flow

    Microsoft Academic Search

    Lu Huilin; Dimitri Gidaspow; Jacques Bouillard; Liu Wentie

    2003-01-01

    The dynamic behavior of gas–solids flow in a 6-m high riser was predicted using a transient two-dimensional (2D) hydrodynamic model based on the kinetic theory of granular flows. Instantaneous and local gas-particle velocity, void fraction and turbulent parameters were obtained. Predicted time-averaged particle concentrations and velocities reflect the classical core-annular flow structure in agreement with experimental measurements, in particular, with

  1. CENTRIFUGAL MEMBRANE FILTRATION

    SciTech Connect

    William A. Greene; Patricia A. Kirk; Richard Hayes; Joshua Riley

    2005-10-28

    SpinTek Membrane Systems, Inc., the developer of a centrifugal membrane filtration technology, has engineered and developed a system for use within the U.S. Department of Energy (DOE) Environmental Management (EM) Program. The technology uses supported microporous membranes rotating at high rpm, under pressure, to separate suspended and colloidal solids from liquid streams, yielding a solids-free permeate stream and a highly concentrated solids stream. This is a crosscutting technology that falls under the Efficient Separations and Processing Crosscutting Program, with potential application to tank wastes, contaminated groundwater, landfill leachate, and secondary liquid waste streams from other remediation processes, including decontamination and decommissioning systems. SpinTek II High Shear Rotary Membrane Filtration System is a unique compact crossflow membrane system that has large, demonstrable advantages in performance and cost compared to currently available systems: (1) High fluid shear prevents membrane fouling even with very high solids content; hazardous and radioactive components can be concentrated to the consistency of a pasty slurry without fouling. (2) Induced turbulence and shear across the membrane increases membrane flux by a factor of ten over existing systems and allows operation on fluids not otherwise treatable. (3) Innovative ceramic membrane and mechanical sealing technology eliminates compatibility problems with aggressive DOE waste streams. (4) System design allows rapid, simple disassembly for inspection or complete decontamination. (5) Produces colloidal- and suspended-solids-free filtrate without the addition of chemicals. The first phase of this project (PRDA maturity stage 5) completed the physical scale-up of the SpinTek unit and verified successful scale-up with surrogate materials. Given successful scale-up and DOE concurrence, the second phase of this project (PRDA maturity stage 6) will provide for the installation and operation of the full-scale two-stage SpinTek unit for treatment of a DOE waste-stream at the Los Alamos National Laboratory. This technology has very broad application across the DOE system. Nineteen DOE technical needs areas (Appendix C) have been identified. Following successful full-scale demonstration for treatment of DOE wastes, this innovative technology will be rapidly deployed on a wide range of waste and process streams throughout the DOE system.

  2. Centrifuges and inertial shear forces.

    PubMed

    van Loon, Jack J W A; Folgering, Erik H T E; Bouten, Carlijn V C; Smit, Theo H

    2004-03-01

    Centrifuges are often used in biological studies for 1 x g control samples in space flight microgravity experiments as well as in ground based research. Using centrifugation as a tool to generate an Earth like acceleration introduces unwanted inertial shear forces to the sample. Depending on the centrifuge and the geometry of the experiment hardware used these shear forces may contribute as much as 99% to the total force acting on the cells or tissues. The inertial shear force artifact should be dealt with for future experiment hardware development for Shuttle and the International Space Station (ISS) as well as for the interpretation of previous spaceflight and on-ground research data. PMID:16145797

  3. Centrifugal microdevices Chip-based analysis systems provide for

    E-print Network

    Rogers, John A.

    Centrifugal microdevices Chip-based analysis systems provide for efficiency gains with respect the potential applications of such instruments. Centrifugation is a well- established sample pre or macromolecules of differing sizes in suspension. Macroscale centrifuges typically generate high centrifugal

  4. The Lifshitz-Kosevich-Shoenberg theory of relativistic electronic gas in neutron stars

    NASA Astrophysics Data System (ADS)

    Wang, Zhaojun; Lü, Guoliang; Zhu, Chunhua

    2014-10-01

    Similar to the de Haas-van Alphen magnetic oscillatory in some normal metals when the Landau quantization is predominant, the magnetic oscillation can also occur in highly degenerate and relativistic electron gas in neutron stars. At large Landau quantum number (Landau quantum number r?2), we generalize the Lifshitz-Kosevich-Shoenberg theory in non-relativistic electron gas to relativistic gas. At small Landau quantum number ( r<2), we expand the grand potential into Fourier series and get similar harmonic oscillatory formula of magnetization. These results indicate that magnetic phase transition similar as Condon transition observed in metals can appear in neutron stars when the differential susceptibility exceeds 1/4 ?.

  5. Centrifugation and the Manhattan Project

    NASA Astrophysics Data System (ADS)

    Reed, Cameron

    2009-04-01

    A study of U. S. Army Manhattan Engineer District documents reveals that consideration of centrifugation as a means of uranium enrichment during World War II was considerably more extensive than is commonly appreciated. By the time the centrifuge project was abandoned in early 1944 a full-scale prototype unit had been fabricated and tested at near-production speeds, enrichments of close to theoretically-expected levels had been demonstrated with pilot-plant units, and plans for production plants had been developed. This paper will review the history of this little-known aspect of the Project and examine the circumstances of how it came to be discontinued.

  6. Centrifugation and the Manhattan Project

    NASA Astrophysics Data System (ADS)

    Reed, Cameron

    2009-05-01

    A study of U. S. Army Manhattan Engineer District documents reveals that consideration of centrifugation as a means of uranium enrichment during World War II was considerably more extensive than is commonly appreciated. By the time the centrifuge project was abandoned in early 1944 a full-scale prototype unit had been fabricated and tested at near-production speeds, enrichments of close to theoretically-expected levels had been demonstrated with pilot-plant units, and plans for production plants had been developed. This paper will review the history of this little-known aspect of the Project and examine the circumstances of how it came to be discontinued.

  7. Gas Dynamics and Kinetics in the Cometary Coma: Theory and Observations

    NASA Technical Reports Server (NTRS)

    Combi, Michael R.; Harris, Walter M.; Smyth, William H.

    2005-01-01

    Our ability to describe the physical state of the expanding coma affects fundamental areas of cometary study both directly and indirectly. In order to convert measured abundances of gas species in the coma to gas production rates, models for the distribution and kinematics of gas species in the coma are required. Conversely, many different types of observations, together with laboratory data and theory, are still required to determine coma model attributes and parameters. Accurate relative and absolute gas production rates and their variations with time and from comet to comet are crucial to our basic understanding of the composition and structure of cometary nuclei and their place in the solar system. We review the gas dynamics and kinetics of cometary comae from both theoretical and observational perspectives, which are important for understanding the wide variety of physical conditions that are encountered.

  8. Centrifugal Filter Devices FOR CONCENTRATION AND PURIFICATION

    E-print Network

    Kirschner, Marc W.

    Centricon® Plus-70 Centrifugal Filter Devices FOR CONCENTRATION AND PURIFICATION OF BIOLOGICAL-70 centrifugal filter is a disposable, single-use device designed for rapid processing of aqueous biological solu- tions in volumes ranging from 15 to 70 mL. It is compatible with swinging-bucket centrifuges

  9. Shape separation of gold nanorods using centrifugation

    E-print Network

    Srinivasarao, Mohan

    Shape separation of gold nanorods using centrifugation Vivek Sharmaa,1 , Kyoungweon Parka,2, and approved January 23, 2009 (received for review January 29, 2008) We demonstrate the use of centrifugation particles to have shape-dependent sedimentation behavior. During centrifugation, nanoparticles undergo

  10. Shallow water model for horizontal centrifugal casting

    Microsoft Academic Search

    J Bohá?ek; A Kharicha; A Ludwig; M Wu

    2012-01-01

    A numerical model was proposed to simulate the solidification process of an outer shell of work roll made by the horizontal centrifugal casting technique. Shallow water model was adopted to solve the 2D average flow dynamics of melt spreading and the average temperature distribution inside the centrifugal casting mould by considering the centrifugal force, Coriolis force, viscous force due to

  11. Quasilinear theory of collisionless electron heating in radio frequency gas discharges

    E-print Network

    Kaganovich, Igor

    Quasilinear theory of collisionless electron heating in radio frequency gas discharges Yu. M. Aliev confinement. Plasma heating by direct current and external high frequency electric fields was also, the effective frequency of electron scatter- ing becomes larger than the usual particle­particle collision

  12. Methane-to-Methanol Conversion by Gas-Phase Transition Metal Oxide Cations: Experiment and Theory

    E-print Network

    Metz, Ricardo B.

    Methane-to-Methanol Conversion by Gas-Phase Transition Metal Oxide Cations: Experiment and Theory-phase transition metal oxide cations can convert methane to methanol. Methane activation by MO+ is discussed-phase transition metal oxides with methane are thus a simple model system for the direct conversion of methane

  13. Quasiclassical Theory of Shubnikov-de Haas Effect in 2D Electron Gas

    Microsoft Academic Search

    B. Laikhtman; E. L. Altshuler

    1994-01-01

    A new approach to the theory of magneto-transport in 2D gas is developed. We make use of Keldysh technique and introduce a modified Green's function which is translationally invariant and gauge invariant. The modification simplifies the calculation of diagrams and allows us to obtain a new helpful addition theorem for the electron wave functions in magnetic field. The modified Green's

  14. Theory of gas hydrates: effect of the approximation of rigid water lattice.

    PubMed

    Pimpalgaonkar, Hrushikesh; Veesam, Shivanand K; Punnathanam, Sudeep N

    2011-08-25

    One of the assumptions of the van der Waals and Platteeuw theory for gas hydrates is that the host water lattice is rigid and not distorted by the presence of guest molecules. In this work, we study the effect of this approximation on the triple-point lines of the gas hydrates. We calculate the triple-point lines of methane and ethane hydrates via Monte Carlo molecular simulations and compare the simulation results with the predictions of van der Waals and Platteeuw theory. Our study shows that even if the exact intermolecular potential between the guest molecules and water is known, the dissociation temperatures predicted by the theory are significantly higher. This has serious implications to the modeling of gas hydrate thermodynamics, and in spite of the several impressive efforts made toward obtaining an accurate description of intermolecular interactions in gas hydrates, the theory will suffer from the problem of robustness if the issue of movement of water molecules is not adequately addressed. PMID:21728316

  15. Post-evaluation of Power Plant Flue Gas Desulfurization Project Based on Theory of Value Management

    Microsoft Academic Search

    Yun-na Wu; Ying-ying Huang; Zhi-jun Huang

    2009-01-01

    With the rapid development of the Thermal Power Plant Flue Gas Desulfurization (FGD) industry, Desulfurization Project has a wide developing prospect in the present market. However, the levels of Desulfurization enterprises mix and owners are unfamiliar with the desulfurization project, which increase the investment and cannot reach the expected desulfurization effect. Applying the theory of value management in post-evaluation of

  16. Centrifugal pumps for rocket engines

    NASA Technical Reports Server (NTRS)

    Campbell, W. E.; Farquhar, J.

    1974-01-01

    The use of centrifugal pumps for rocket engines is described in terms of general requirements of operational and planned systems. Hydrodynamic and mechanical design considerations and techniques and test procedures are summarized. Some of the pump development experiences, in terms of both problems and solutions, are highlighted.

  17. Preliminary design of centrifugal compressors

    SciTech Connect

    Kocak, S. [Selcuk Univ., Konya (Turkey). Dept. of Mechanical Engineering

    1996-11-01

    Preliminary design calculations are analyzed for a centrifugal compressor, after choosing as the type of the turbomachine from the curves given by Balje (1981). In impeller calculations, the effect of slip factor on exit conditions, the inducer geometry and the effect of choked flow on relative Mach number are investigated. In discharge calculation vaned diffusers are compared with vaneless diffusers.

  18. Life Sciences Centrifuge Facility review

    NASA Technical Reports Server (NTRS)

    Young, Laurence R.

    1994-01-01

    The Centrifuge Facility Project at ARC was reviewed by a code U team to determine appropriateness adequacy for the ISSA. This report represents the findings of one consultant to this team and concentrates on scientific and technical risks. This report supports continuation of the project to the next phase of development.

  19. Life Sciences Centrifuge Facility assessment

    NASA Technical Reports Server (NTRS)

    Benson, Robert H.

    1994-01-01

    This report provides an assessment of the status of the Centrifuge Facility being developed by ARC for flight on the International Space Station Alpha. The assessment includes technical status, schedules, budgets, project management, performance of facility relative to science requirements, and identifies risks and issues that need to be considered in future development activities.

  20. Colloid centrifugation of boar semen.

    PubMed

    Morrell, J M; Wallgren, M

    2011-09-01

    Colloid centrifugation of boar semen has been reported sporadically for at least the last two decades, beginning with density gradient centrifugation (DGC) and progressing more recently to single layer centrifugation (SLC). Single layer centrifugation through a species-specific colloid has been shown to be effective in selecting the best spermatozoa (spermatozoa with good motility and normal morphology) from boar sperm samples. The method is easier to use and less time-consuming than DGC and has been scaled-up to allow whole ejaculates from other species, e.g. stallions, to be processed in a practical manner. The SLC technique is described, and various scale-up versions are presented. The potential applications for SLC in boar semen preservation are as follows: to improve sperm quality in artificial insemination (AI) doses for 'problem' boars; to increase the shelf-life of normal stored sperm samples, either by processing the fresh semen before preparing AI doses or by processing the stored semen dose to extract the best spermatozoa; to remove pathogens (viruses, bacteria), thus improving biosecurity of semen doses and potentially reducing the use of antibiotics; to improve cryosurvival by removing dead and dying spermatozoa prior to cryopreservation; to select spermatozoa for in vitro fertilization. These applications are discussed and practical examples are provided. Finally, a few thoughts about the economic value of the technique to the boar semen industry are presented. PMID:21884271

  1. Prototyping of ultra micro centrifugal compressor-influence of meridional configuration

    Microsoft Academic Search

    Toshiyuki Hirano; Tadataka Muto; Hoshio Tsujita

    2011-01-01

    In order to investigate the design method for a micro centrifugal compressor, which is the most important component of an\\u000a ultra micro gas turbine, two types of centrifugal impeller with 2-dimensional blade were designed, manufactured and tested.\\u000a These impellers have different shapes of hub on the meridional plane with each other. Moreover, these types of impeller were\\u000a made for the

  2. Biot-Gassmann theory for velocities of gas hydrate-bearing sediments

    USGS Publications Warehouse

    Lee, M.W.

    2002-01-01

    Elevated elastic velocities are a distinct physical property of gas hydrate-bearing sediments. A number of velocity models and equations (e.g., pore-filling model, cementation model, effective medium theories, weighted equations, and time-average equations) have been used to describe this effect. In particular, the weighted equation and effective medium theory predict reasonably well the elastic properties of unconsolidated gas hydrate-bearing sediments. A weakness of the weighted equation is its use of the empirical relationship of the time-average equation as one element of the equation. One drawback of the effective medium theory is its prediction of unreasonably higher shear-wave velocity at high porosities, so that the predicted velocity ratio does not agree well with the observed velocity ratio. To overcome these weaknesses, a method is proposed, based on Biot-Gassmann theories and assuming the formation velocity ratio (shear to compressional velocity) of an unconsolidated sediment is related to the velocity ratio of the matrix material of the formation and its porosity. Using the Biot coefficient calculated from either the weighted equation or from the effective medium theory, the proposed method accurately predicts the elastic properties of unconsolidated sediments with or without gas hydrate concentration. This method was applied to the observed velocities at the Mallik 2L-39 well, Mackenzie Delta, Canada.

  3. Moderately dense gas quantum kinetic theory: Aspects of pair correlations R. F. Snider and G. W. Wei

    E-print Network

    Wei, Guo-Wei

    their decay via interactions with other particles in the gas. The molecular description is given of such a gasModerately dense gas quantum kinetic theory: Aspects of pair correlations R. F. Snider and G. W. Wei Department of Chemistry, University of British Columbia, Vancouver V6T 1Z1, Canada J. G. Muga

  4. Centrifugal separator devices, systems and related methods

    DOEpatents

    Meikrantz, David H. (Idaho Falls, ID); Law, Jack D. (Pocatello, ID); Garn, Troy G. (Idaho Falls, ID); Todd, Terry A. (Aberdeen, ID); Macaluso, Lawrence L. (Carson City, NV)

    2012-03-20

    Centrifugal separator devices, systems and related methods are described. More particularly, fluid transfer connections for a centrifugal separator system having support assemblies with a movable member coupled to a connection tube and coupled to a fixed member, such that the movable member is constrained to movement along a fixed path relative to the fixed member are described. Also, centrifugal separator systems including such fluid transfer connections are described. Additionally, methods of installing, removing and/or replacing centrifugal separators from centrifugal separator systems are described.

  5. Liquid/Gas Vortex Separator

    NASA Technical Reports Server (NTRS)

    Morris, B. G.

    1986-01-01

    Liquid/gas separator vents gas from tank of liquid that contains gas randomly distributed in bubbles. Centrifugal force separates liquid and gas, forcing liquid out of vortex tube through venturi tube. Gas vented through exhaust port. When liquid detected in vent tube, exhaust port closed, and liquid/gas mixture in vent tube drawn back into tank through venturi.

  6. Photoionization of Benzophenone in the Gas Phase: Theory and Experiment.

    PubMed

    Khemiri, Noura; Messaoudi, Sabri; Abderrabba, Manef; Spighi, Gloria; Gaveau, Marc-André; Briant, Marc; Soep, Benoît; Mestdagh, Jean-Michel; Hochlaf, Majdi; Poisson, Lionel

    2015-06-11

    We report on the single photoionization of jet-cooled benzophenone using a tunable source of VUV synchrotron radiation coupled with a photoion/photoelectron coincidence acquisition device. The assignment and the interpretation of the spectra are based on a characterization by ab initio and density functional theory calculations of the geometry and of the electronic states of the cation. The absence of structures in the slow photoelectron spectrum is explained by a congestion of the spectrum due to the dense vibrational progressions of the very low frequency torsional mode in the cation either in pure form or in combination bands. Also a high density of electronic states has been found in the cation. Presently, we estimate the experimental adiabatic and vertical ionization energy of benzophenone at 8.80 ± 0.01 and 8.878 ± 0.005 eV, respectively. The ionization energy as well as the energies of the excited states are compared to the calculated ones. PMID:25866992

  7. Application of Watson's centrifugal distortion theory to water and light asymmetric tops. General methods. Analysis of the ground state and the nu2 state of D2O16

    Microsoft Academic Search

    Guy Steenbeckeliers; Jean Bellet

    1973-01-01

    Watson's reduced Hamiltonian proved adapted for treating the rotation of light molecules which show very large effects of centrifugal distortion. In order to determine which terms are required and which are negligible (choice of an effective model), we have studied the order of magnitude of the terms from a theoretical point of view. This order depends on the coefficient and

  8. The Detection Rate of Molecular Gas in Elliptical Galaxies: Constraints on Galaxy Formation Theories

    E-print Network

    Yutaka Fujita; Masahiro Nagashima; Naoteru Gouda

    2000-05-15

    In order to constrain parameters in galaxy formation theories, especially those for a star formation process, we investigate cold gas in elliptical galaxies. We calculate the detection rate of cold gas in them using a semi-analytic model of galaxy formation and compare it with observations. We show that the model with a long star formation time-scale (~20 Gyr) is inconsistent with observations. Thus, some mechanisms of reducing the mass of interstellar medium, such as the consumption of molecular gas by star formation and/or reheating from supernovae, are certainly effective in galaxies. Our model predicts that star formation induced when galaxies in a halo collide each other reduces the cold gas left until the present. However, we find that the reduction through random collisions of satellite (non-central) galaxies in mean free time-scale in a halo is not required to explain the observations. This may imply that the collisions and mergers between satellite galaxies do not occur so often in clusters or that they do not stimulate the star formation activity as much as the simple collision model we adopted. For cD galaxies, the predicted detection rate of cold gas is consistent with observations as long as the transformation of hot gas into cold gas is prevented in halos whose circular velocities are larger than 500 km s^-1. Moreover, we find that the cold gas brought into cDs through captures of gas-rich galaxies is little. We also show that the fraction of galaxies with observable cold gas should be small for cluster ellipticals in comparison with that for field ellipticals.

  9. The Function of Gas Vesicles in Halophilic Archaeaand Bacteria: Theories and Experimental Evidence

    PubMed Central

    Oren, Aharon

    2012-01-01

    A few extremely halophilic Archaea (Halobacterium salinarum, Haloquadratum walsbyi, Haloferax mediterranei, Halorubrum vacuolatum, Halogeometricum borinquense, Haloplanus spp.) possess gas vesicles that bestow buoyancy on the cells. Gas vesicles are also produced by the anaerobic endospore-forming halophilic Bacteria Sporohalobacter lortetii and Orenia sivashensis. We have extensive information on the properties of gas vesicles in Hbt. salinarum and Hfx. mediterranei and the regulation of their formation. Different functions were suggested for gas vesicle synthesis: buoying cells towards oxygen-rich surface layers in hypersaline water bodies to prevent oxygen limitation, reaching higher light intensities for the light-driven proton pump bacteriorhodopsin, positioning the cells optimally for light absorption, light shielding, reducing the cytoplasmic volume leading to a higher surface-area-to-volume ratio (for the Archaea) and dispersal of endospores (for the anaerobic spore-forming Bacteria). Except for Hqr. walsbyi which abounds in saltern crystallizer brines, gas-vacuolate halophiles are not among the dominant life forms in hypersaline environments. There only has been little research on gas vesicles in natural communities of halophilic microorganisms, and the few existing studies failed to provide clear evidence for their possible function. This paper summarizes the current status of the different theories why gas vesicles may provide a selective advantage to some halophilic microorganisms. PMID:25371329

  10. Molecular density functional theory for water with liquid-gas coexistence and correct pressure

    NASA Astrophysics Data System (ADS)

    Jeanmairet, Guillaume; Levesque, Maximilien; Sergiievskyi, Volodymyr; Borgis, Daniel

    2015-04-01

    The solvation of hydrophobic solutes in water is special because liquid and gas are almost at coexistence. In the common hypernetted chain approximation to integral equations, or equivalently in the homogenous reference fluid of molecular density functional theory, coexistence is not taken into account. Hydration structures and energies of nanometer-scale hydrophobic solutes are thus incorrect. In this article, we propose a bridge functional that corrects this thermodynamic inconsistency by introducing a metastable gas phase for the homogeneous solvent. We show how this can be done by a third order expansion of the functional around the bulk liquid density that imposes the right pressure and the correct second order derivatives. Although this theory is not limited to water, we apply it to study hydrophobic solvation in water at room temperature and pressure and compare the results to all-atom simulations. The solvation free energy of small molecular solutes like n-alkanes and hard sphere solutes whose radii range from angstroms to nanometers is now in quantitative agreement with reference all atom simulations. The macroscopic liquid-gas surface tension predicted by the theory is comparable to experiments. This theory gives an alternative to the empirical hard sphere bridge correction used so far by several authors.

  11. Unstable flow in centrifugal fans

    SciTech Connect

    Chen, P. [Nanyang Technological Univ., Singapore (Singapore). School of Mechanical and Production Engineering; Soundra-Nayagam, M. [Loughborough Univ. of Technology (United Kingdom). Dept. of Electrical and Electronics Engineering; Bolton, A.N. [National Engineering Lab., Glasgow (United Kingdom). Flow Center; Simpson, H.C. [Univ. of Strathclyde, Glasgow (United Kingdom). Dept. of Mechanical and Processing Engineering

    1996-03-01

    Rotating stall and the inlet vortex in centrifugal fans with inlet vane control has been studied. The advances in stall research in aero-engine compressors are discussed. The present study shows that stall in centrifugal fans can be quite different from that in axial compressors, in that stall can occur in a progressive and intermittent fashion. The study also shows that a discontinuity in the fan characteristic is not necessarily accompanied by rotating stall, unlike the axial machines. Experimental results indicate that the positive prewhirl created by inlet vanes tends to delay the occurrence of stall. Also, dorsal fin devices that are used to control the inlet vortex do not seem to affect the stall point unfavorably. The inlet vortex frequency was found to invariably exhibit a linear relation with the flow rate even when dorsal fins were used. This offers a practical method to distinguish between the inlet vortex and rotating stall.

  12. Sine-Gordon mean field theory of a Coulomb gas Alexandre Diehl, Marcia C. Barbosa, and Yan Levin

    E-print Network

    Levin, Yan

    Sine-Gordon mean field theory of a Coulomb gas Alexandre Diehl, Marcia C. Barbosa, and Yan Levin, Rio Grande do Sul, Brazil Received 6 November 1996 Sine-Gordon field theory is used to investigate potential, the sine-Gordon theory predicts the phase diagram topologically identical to the Monte Carlo

  13. Deburring by centrifugal barrel tumbling

    Microsoft Academic Search

    Gillespie

    1976-01-01

    The reliability of small precision mechanisms greatly depends upon the production of burr-free, sharp-edged parts. Centrifugal barrel finishing (Harperizing) is one of the few processes capable of producing these conditions. Burrs less than 0.001-in. thick by 0.001-in. high (25.4 x 25.4 ..mu..m) can be removed from 303 Se stainless steel, 1018 steel, and 6061-T6 aluminum with dimensional changes in the

  14. Sound generation in centrifugal compressors

    Microsoft Academic Search

    Till Raitor; Wolfgang Neise

    2008-01-01

    An experimental study is described to explore the dominant sound generation mechanisms of the spectral components governing the overall noise level of centrifugal compressors. At the design speed with supersonic flow conditions in the rotor blade channels, blade tone noise and buzz-saw noise are the main contributors. On the inlet, rotor-alone noise is the main source while rotor–stator interaction noise

  15. Quantum scattering theory of rotational relaxation and spectral line shapes in H2He gas mixtures

    Microsoft Academic Search

    Richard Shafer; Roy G. Gordon

    1973-01-01

    A systematic study is presented of the rotational relaxation and spectral line shape properties of dilute gas mixtures of H2 in He, in an effort to determine the radial and angular dependence of the H2&sngbnd;He intermolecular potential. The quantum mechanical theory of relaxation in gases is reviewed, and we express the results in terms of a matrix of cross sections

  16. Role of Chameleon Field in presence of Variable Modified Chaplygin gas in Brans-Dicke Theory

    E-print Network

    Shuvendu Chakraborty; Ujjal Debnath

    2011-08-23

    In this work, we have considered FRW model of the universe for Brans-Dicke (BD) theory with BD scalar field as a Chameleon field. First we have transformed the field equations and conservation equation from Jordan's frame to Einstein's frame. We have shown in presence of variable modified Chaplygin gas, the potential function $V$ and another analytic function $f$ always increase with respect to BD-Chameleon scalar field $\\phi$.

  17. Radial distributions of arm-gas offsets as an observational test of spiral theories

    NASA Astrophysics Data System (ADS)

    Baba, Junichi; Morokuma-Matsui, Kana; Egusa, Fumi

    2015-06-01

    Theories of stellar spiral arms in disk galaxies can be grouped into two classes based on the longevity of a spiral arm. Although the quasi-stationary density wave theory supposes that spirals are rigidly rotating, long-lived patterns, the dynamic spiral theory predicts that spirals are differentially rotating, transient, recurrent patterns. In order to distinguish between the two spiral models from observations, we performed hydrodynamic simulations with steady and dynamic spiral models. Hydrodynamic simulations in steady spiral models demonstrated that the dust lane locations relative to the stellar spiral arms (hereafter, arm-gas offsets) depend on radius, regardless of the strength and pitch angle of the spiral and the model of the interstellar medium. In contrast, we found that the dynamic spiral models show no systematic radial dependence of the arm-gas offsets. The arm-gas offset radial profile method, together with the other test methods, will help us to distinguish between the two spiral models in observed spiral galaxies.

  18. Modeling gas displacement kinetics in coal with Maxwell-Stefan diffusion theory

    SciTech Connect

    Wei, X.R.; Wang, G.X.; Massarotto, P.; Rudolph, V.; Golding, S.D. [University of Queensland, Brisbane, Qld. (Australia). Division of Chemical Engineering

    2007-12-15

    The kinetics of binary gas counter-diffusion and Darcy flow in a large coal sample were modeled, and the results compared with data from experimental laboratory investigations. The study aimed for a better understanding of the CO{sub 2}-sequestration enhanced coalbed methane (ECBM) recovery process. The transport model used was based on the bidisperse diffusion mechanism and Maxwell-Stefan (MS) diffusion theory. This provides an alternative approach to simulate multicomponent gas diffusion and flow in bulk coals. A series of high-stress core flush tests were performed on a large coal sample sourced from a Bowen Basin coal mine in Queensland, Australia to investigate the kinetics of one gas displacing another. These experimental results were used to derive gas diffusivities, and to examine the predictive capability of the diffusion model. The simulations show good agreements with the displacement experiments revealing that MS diffusion theory is superior for describing diffusion of mixed gases in coals compared with the constant Fick diffusivity model. The optimized effective micropore and macropore diffusivities are comparable with experimental measurements achieved by other researchers.

  19. CFD simulation of centrifugal cells washers.

    PubMed

    Kellet, Beth E; Binbing, Han; Dandy, David S; Wickramasinghe, S Ranil

    2004-01-01

    The feasibility of using computational fluid dynamics to guide the design of better centrifuges for processing shed blood is explored here. The velocity field and the rate of protein removal from the shed blood have been studied. The results indicate that computational fluid dynamics could help screen preliminary centrifuge bowl designs thus reducing the number of initial experimental tests required when developing new centrifuge bowls. Though the focus of this work is on washing shed blood the methods developed here are applicable to the design of centrifuge bowls for other blood processing applications. PMID:15133962

  20. Centrifugal separators and related devices and methods

    DOEpatents

    Meikrantz, David H. (Idaho Falls, ID); Law, Jack D. (Pocatello, ID); Garn, Troy G. (Idaho Falls, ID); Macaluso, Lawrence L. (Carson City, NV); Todd, Terry A. (Aberdeen, ID)

    2012-03-06

    Centrifugal separators and related methods and devices are described. More particularly, centrifugal separators comprising a first fluid supply fitting configured to deliver fluid into a longitudinal fluid passage of a rotor shaft and a second fluid supply fitting sized and configured to sealingly couple with the first fluid supply fitting are described. Also, centrifugal separator systems comprising a manifold having a drain fitting and a cleaning fluid supply fitting are described, wherein the manifold is coupled to a movable member of a support assembly. Additionally, methods of cleaning centrifugal separators are described.

  1. Open-cycle centrifugal vapor-compression heat pump. Annual report, March 1983-February 1984

    SciTech Connect

    Iles, T.L.; Burgmeier, L.R.; Stanko, J.E.

    1984-04-01

    The objectives of this program are: (1) to develop an open-cycle high-lift centrifugal steam compressor system that can be efficiently retrofitted to existing multi-effect and high-temperature differential evaporators while maintaining the cost benefits of a single-stage centrifugal compressor and (2) to demonstrate the energy saving and cost benefits of driving the compressor with a natural-gas-fueled gas turbine engine. The turbine exhaust will be used for final drying of the product that was evaporated. This report describes the design and fabrication of the system and the test activities through February 1984.

  2. Open-cycle centrifugal vapor-compression heat pump. Annual report, March 1984-February 1985

    SciTech Connect

    Iles, T.L.; Burgmeier, L.R.; Liu, A.Y.

    1985-04-01

    The objectives of the program are to (1) develop an open-cycle high-lift centrifugal steam compressor system that can be efficiently retrofitted to existing multi-effect and high-temperature differential evaporators while maintaining the cost benefits of a single-stage centrifugal compressor and (2) demonstrate the energy saving and cost benefits of driving the compressor with a natural-gas-fueled gas turbine engine. The turbine exhaust will be used for final drying of the product that was evaporated. This report describes the design and fabrication of the system and the test activities through February 1985.

  3. Centrifugal quantum states of neutrons

    E-print Network

    V. V. Nesvizhevsky; A. K. Petukhov; K. V. Protasov; A. Yu. Voronin

    2008-06-24

    We propose a method for observation of the quasi-stationary states of neutrons, localized near the curved mirror surface. The bounding effective well is formed by the centrifugal potential and the mirror Fermi-potential. This phenomenon is an example of an exactly solvable "quantum bouncer" problem that could be studied experimentally. It could provide a promising tool for studying fundamental neutron-matter interactions, as well as quantum neutron optics and surface physics effects. We develop formalism, which describes quantitatively the neutron motion near the mirror surface. The effects of mirror roughness are taken into account.

  4. Density and Buoyancy with Centrifugation

    NSDL National Science Digital Library

    In this activity, by the Concord Consortium's Molecular Literacy project, students "have an opportunity to explore the relationship between atomic mass, volume, and density, and relate these to the technique of centrifugation." The activity itself is a java-based interactive resource built upon the free, open source Molecular Workbench software. In the activity, students are allowed to explore at their own pace in a digital environment of demonstrations and simulations which allow them to print reports of data captured. In addition, visitors will find an overview and list of objectives, a test and rubric, a supplementary classroom activity, and central concepts.

  5. Stress analysis of bolted joints under centrifugal force

    NASA Astrophysics Data System (ADS)

    Imura, Makoto; Iizuka, Motonobu; Nakae, Shigeki; Mori, Takeshi; Koyama, Takayuki

    2014-06-01

    Our objective is to develop a long-life rotary machine for synchronous generators and motors. To do this, it is necessary to design a high-strength bolted joint, which is responsible for fixing a salient pole on a rotor shaft. While the rotary machine is in operation, not only centrifugal force but also moment are loaded on a bolted joint, because a point of load is eccentric to a centre of a bolt. We tried to apply the theory proposed in VDI2230-Blatt1 to evaluate the bolted joint under eccentric force, estimate limited centrifugal force, which is the cause of partial separation between the pole and the rotor shaft, and then evaluate additional tension of a bolt after the partial separation has occurred. We analyzed the bolted joint by FEM, and defined load introduction factor in that case. Additionally, we investigated the effect of the variation of bolt preload on the partial separation. We did a full scale experiment with a prototype rotor to reveal the variation of bolt preload against tightening torque. After that, we verified limited centrifugal force and the strength of the bolted joint by the VDI2230-Blatt1 theory and FEM considering the variation of bolt preload. Finally, we could design a high-strength bolted joint verified by the theoretical study and FEM analysis.

  6. Influence of the positive prewhirl on the performance of centrifugal pumps with different airfoils

    NASA Astrophysics Data System (ADS)

    Zhou, C. M.; Wang, H. M.; Huang, X.; Lin, H.

    2012-11-01

    According to the basic theory of turbomachinery design and inlet guide vanes prewhirl regulation, two different airfoils inlet guide vanes of prewhirl regulation device were designed, the influence of the positive prewhirl to the performance of centrifugal pump were studied based on different airfoils. The results show that, for a single-suction centrifugal pump: Gottingen bowed blade-type inlet guide vane adjustment effect is better than straight blade-type inlet guide; appropriate design of positive prewhirl can elevate the efficiency of centrifugal pumps. Compared with no vane conditions, the efficiency of centrifugal pump with prewhirl vanes has been greatly improved and the power consumption has been reduced significantly, while has little influence on the head.

  7. Centrifuge Modelling of the Performance of Liquefaction Mitigation Measures for

    E-print Network

    Centrifuge Modelling of the Performance of Liquefaction Mitigation Measures for Shallow Foundations Centrifuge Stored Angular Momentum Actuator Equivalent Shear Beam Container Automatic Sand Pourer Hostun Sand Methylcellulose 3 #12;Experimental Techniques and Materials 10 m Turner Beam Centrifuge Stored

  8. Light weight gas turbine engine fuel pumping technology

    SciTech Connect

    Kassel, J.M.; Birdsall, J.

    1989-01-01

    The paper discusses the use of a single high speed centrifugal fuel pump as the only pump in a gas turbine engine fuel system. The characteristics and requirements of the high speed centrifugal fuel pump system are compared with a more traditional fuel pump system. The application of composite technology to the high speed centrifugal pump concept is also reviewed.

  9. The Energetics of Centrifugal Instability

    NASA Astrophysics Data System (ADS)

    Dewar, W. K.; Jiao, Y.

    2014-12-01

    A recent study has argued that the California Undercurrent, and poleward eastern boundary currents in general, generate mixing events through centrifugal instability (CI). Conditions favorable for CI are created by the strong horizontal shears developed in turbulent bottom layers of currents flowing in the direction of topographic waves. At points of abrupt topographic change, like promontories and capes, the coastal current separates from the boundary and injects gravitationally stable but dynamically unstable flow into the interior. The resulting finite amplitude development of the instability involves overturnings and diabatic mixing. The purpose of this study is to examine the energetics of CI in order to characterize it as has been done for other instabilities and develop a framework in which to estimate its regional and global impacts. We argue that CI is roughly twice as efficient at mixing as is Kelvin-Helmholtz instability, and that roughly 10% of the initial energy in a CUC-like current is lost to either local mixing or the generation of unbalanced flows. The latter probably leads to non-local mixing. Thus centrifugal instability is an effective process by which energy is lost from the balanced flow and spent in mixing neighboring water masses. We argue the importance of the mixing is regional in nature, but of less importance to the global budgets given its regional specificity.

  10. Centrifuge modelling of granular flows

    NASA Astrophysics Data System (ADS)

    Cabrera, Miguel Angel; Wu, Wei

    2015-04-01

    A common characteristic of mass flows like debris flows, rock avalanches and mudflows is that gravity is their main driving force. Gravity defines the intensity and duration of the main interactions between particles and their surrounding media (particle-particle, particle-fluid, fluid-fluid). At the same time, gravity delimits the occurrence of phase separation, inverse segregation, and mass consolidation, among other phenomena. Therefore, in the understanding of the flow physics it is important to account for the scaling of gravity in scaled models. In this research, a centrifuge model is developed to model free surface granular flows down an incline at controlled gravity conditions. Gravity is controlled by the action of an induced inertial acceleration field resulting from the rotation of the model in a geotechnical centrifuge. The characteristics of the induced inertial acceleration field during flow are discussed and validated via experimental data. Flow heights, velocity fields, basal pressure and impact forces are measured for a range of channel inclinations and gravity conditions. Preliminary results enlighten the flow characteristics at variable gravity conditions and open a discussion on the simulation of large scale processes at a laboratory scale. Further analysis on the flow physics brings valuable information for the validation of granular flows rheology.

  11. Solid deuterium centrifuge pellet injector

    SciTech Connect

    Foster, C.A.

    1982-01-01

    Pellet injectors are needed to fuel long pulse tokamak plasmas and other magnetic confinement devices. For this purpose, an apparatus has been developed that forms 1.3-mm-diam pellets of frozen deuterium at a rate of 40 pellets per second and accelerates them to a speed of 1 km/s. Pellets are formed by extruding a billet of solidified deuterium through a 1.3-mm-diam nozzle at a speed of 5 cm/s. The extruding deuterium is chopped with a razor knife, forming 1.3-mm right circular cylinders of solid deuterium. The pellets are accelerated by synchronously injecting them into a high speed rotating arbor containing a guide track, which carries them from a point near the center of rotation to the periphery. The pellets leave the wheel after 150/sup 0/ of rotation at double the tip speed. The centrifuge is formed in the shape of a centrifugal catenary and is constructed of high strength KEVLAR/epoxy composite. This arbon has been spin-tested to a tip speed of 1 km/s.

  12. Solid deuterium centrifuge pellet injector

    SciTech Connect

    Foster, C.A.

    1983-04-01

    Pellet injectors are needed to fuel long pulse tokamak plasmas and other magnetic confinement devices. For this purpose, an apparatus has been developed that forms 1.3-mm-diam pellets of frozen deuterium at a rate of 40 pellets per second and accelerates them to a speed of 1 km/s. Pellets are formed by extruding a billet of solidified deuterium through a 1.3-mm-diam nozzle at a speed of 5 cm/s. The extruding deuterium is chopped with a razor knife, forming 1.3-mm right circular cylinders of solid deuterium. The pellets are accelerated by synchronously injecting them into a high speed rotating arbor containing a guide track, which carries them from a point near the center of rotation to the periphery. The pellets leave the wheel after 150/sup 0/ of rotation at double the tip speed. The centrifuge is formed in the shape of a centrifugal catenary and is constructed of high strength Kevlar/epoxy composite. This arbor has been spin-tested to a tip speed of 1 km/s.

  13. Gas production in the Barnett Shale obeys a simple scaling theory.

    PubMed

    Patzek, Tad W; Male, Frank; Marder, Michael

    2013-12-01

    Natural gas from tight shale formations will provide the United States with a major source of energy over the next several decades. Estimates of gas production from these formations have mainly relied on formulas designed for wells with a different geometry. We consider the simplest model of gas production consistent with the basic physics and geometry of the extraction process. In principle, solutions of the model depend upon many parameters, but in practice and within a given gas field, all but two can be fixed at typical values, leading to a nonlinear diffusion problem we solve exactly with a scaling curve. The scaling curve production rate declines as 1 over the square root of time early on, and it later declines exponentially. This simple model provides a surprisingly accurate description of gas extraction from 8,294 wells in the United States' oldest shale play, the Barnett Shale. There is good agreement with the scaling theory for 2,057 horizontal wells in which production started to decline exponentially in less than 10 y. The remaining 6,237 horizontal wells in our analysis are too young for us to predict when exponential decline will set in, but the model can nevertheless be used to establish lower and upper bounds on well lifetime. Finally, we obtain upper and lower bounds on the gas that will be produced by the wells in our sample, individually and in total. The estimated ultimate recovery from our sample of 8,294 wells is between 10 and 20 trillion standard cubic feet. PMID:24248376

  14. Gas production in the Barnett Shale obeys a simple scaling theory

    PubMed Central

    Patzek, Tad W.; Male, Frank; Marder, Michael

    2013-01-01

    Natural gas from tight shale formations will provide the United States with a major source of energy over the next several decades. Estimates of gas production from these formations have mainly relied on formulas designed for wells with a different geometry. We consider the simplest model of gas production consistent with the basic physics and geometry of the extraction process. In principle, solutions of the model depend upon many parameters, but in practice and within a given gas field, all but two can be fixed at typical values, leading to a nonlinear diffusion problem we solve exactly with a scaling curve. The scaling curve production rate declines as 1 over the square root of time early on, and it later declines exponentially. This simple model provides a surprisingly accurate description of gas extraction from 8,294 wells in the United States’ oldest shale play, the Barnett Shale. There is good agreement with the scaling theory for 2,057 horizontal wells in which production started to decline exponentially in less than 10 y. The remaining 6,237 horizontal wells in our analysis are too young for us to predict when exponential decline will set in, but the model can nevertheless be used to establish lower and upper bounds on well lifetime. Finally, we obtain upper and lower bounds on the gas that will be produced by the wells in our sample, individually and in total. The estimated ultimate recovery from our sample of 8,294 wells is between 10 and 20 trillion standard cubic feet. PMID:24248376

  15. Centrifuging additive-containing motor oils

    Microsoft Academic Search

    A. V. Nepogod'ev; V. I. Vorozhikhina; L. S. Ryazanov

    1968-01-01

    1.Centrifugal filters installed on diesel engines do not remove from fresh oils any soluble additives that have been added to the oils.2.The sediment formation that occurs during standing or centrifuging of oils containing certain additives is a consequence of inadequate treatment of these additives to remove foreign contaminants during manufacture.

  16. Centrifugal pumps for the practicing engineer

    Microsoft Academic Search

    Benaroya

    1978-01-01

    This book, intended for engineering students and practicing engineers, dwells exclusively on the fundamentals required for the efficient design of systems applying centrifugal pumps. The reader is guided, step by step, through all the required fundamentals needed for the sound and efficient design of pumping systems employing centrifugal pumps. Examples accompany each group of introduced and developed concepts and formulae;

  17. Astronaut Gordon Cooper in centrifuge for tests

    NASA Technical Reports Server (NTRS)

    1963-01-01

    Astronaut L. Gordon Cooper, prime pilot for the Mercury-Atlas 9 mission, is strapped into the gondola while undergoing tests in the centrifuge at the Naval Air Development Center, Johnsville, Pennsylvania. The centrifuge is used to investigate by simulation the pilot's capability to control the vehicle during the actual flight in its booster and reentry profile.

  18. The Development of a Centrifugal Compressor Impeller

    Microsoft Academic Search

    C. Xu; R. S. Amano

    2009-01-01

    An impeller is one of the key components of industrial centrifugal compressors and turbochargers. Aerodynamic and structure designs of the impeller are critical to the success of the whole compressor stages. The requirements for efficiency and operating range of industrial centrifugal compressors and turbochargers have been increased dramatically compared with the situation in the past. The efficiency of a newly

  19. The Initial Design of a Centrifugal Compressor

    Microsoft Academic Search

    E. SWAIN

    1992-01-01

    Centrifugal compressors are used in many different applications in a wide variety of industries. Although there are a number of centrifugal compressor variants a particular type has been chosen upon which to concentrate. This is a single-state machine without inlet guide vanes and with a shroudless backswept impeller, a vaned diffuser and a volute collector. The focus of this article

  20. A method of centrifugal compressor performance prediction

    Microsoft Academic Search

    M. V. Herbert

    1979-01-01

    Predictions of compressor performance are often wanted for tentative designs where the detailed geometry of blade shapes and flow passages is not completely specified. A method of performance prediction for centrifugal compressors has been developed which requires knowledge of only overall dimensions and blade angles. This method can be applied to any centrifugal compressor with radial outflow (i.e. with no

  1. Centrifugal deformations of the gravitational kink

    E-print Network

    Paolo Maraner; Jiannis K. Pachos

    2008-11-29

    The Kaluza-Klein reduction of 4d conformally flat spacetimes is reconsidered. The corresponding 3d equations are shown to be equivalent to 2d gravitational kink equations augmented by a centrifugal term. For space-like gauge fields and non-trivial values of the centrifugal term the gravitational kink solutions describe a spacetime that is divided in two disconnected regions.

  2. Centrifugally driven diffusion of Iogenic plasma

    Microsoft Academic Search

    G. L. Siscoe; Danny Summers

    1981-01-01

    The plasma distribution around Io as measured by Voyager 1 displays an asymmetric discontinuity at Io's orbit that has been suggested to be the signature of centrifugally driven interchange diffusion fed by plasma derived from Io. This hypothesis is explored further and found to be valid. The particular form for the diffusion coefficient appropriate to centrifugally driven turbulence is derived.

  3. Centrifugal enhancement of retroviral mediated gene transfer

    Microsoft Academic Search

    Alfred B. Bahnsonz; James T. Dunigan; Bora E. Baysal; Trina Mohney; R. Wayne Atchison; Maya T. Nimgaonkar; Edward D. Ball; John A. Barranger

    1995-01-01

    Centrifugation has been used for many years to enhance infection of cultured cells with a variety of different types of viruses, but it has only recently been demonstrated to be effective for retroviruses (Ho et al. (1993) J. Leukocyte Biol. 53, 208–212; Kotani et al. (1994) Hum. Gene Ther. 5, 19–28). Centrifugation was investigated as a means of increasing the

  4. Submarine landslide flows simulation through centrifuge modelling

    E-print Network

    Gue, Chang Shin

    2012-05-08

    SUBMARINE LANDSLIDE FLOWS SIMULATION THROUGH CENTRIFUGE MODELLING by Chang Shin GUE A dissertation submitted for the degree of Doctor of Philosophy at the University of Cambridge Churchill College January... “Continuous effort – not strength or intelligence – is the key to unlocking our potential” - Winston Churchill ABSTRACT SUBMARINE LANDSLIDE FLOWS SIMULATION THROUGH CENTRIFUGE MODELLING Chang Shin GUE Landslides occur both onshore...

  5. Apparatus for centrifugal separation of coal particles

    DOEpatents

    Dickie, William (New Eagle, PA); Cavallaro, Joseph A. (Mt. Keesport, PA); Killmeyer, Richard P. (Pleasant Hills, PA)

    1991-01-01

    A gravimetric cell for centrifugal separation of fine coal by density has a cylindrical body and a butterfly valve or other apparatus for selectively sealing the body radially across the approximate center of the cylinder. A removable top is provided which seals the cylinder in the centrifuge and in unvented areas.

  6. Apparatus for centrifugal separation of coal particles

    SciTech Connect

    Dickie, W.; Cavallaro, J.A.; Killmeyer, R.P.

    1988-08-30

    A gravimetric cell was designed for the centrifugal separation of coal. It has a cylindrical body and a butterfly valve or other apparatus for selectively sealing the body radially across the approximate center of the cylinder. A removable top is provided which seals the cylinder in the centrifuge and in unvented areas. 2 figs.

  7. Apparatus for centrifugal separation of coal particles

    SciTech Connect

    Dickie, W.; Cavallaro, J.A.; Killmeyer, R.P.

    1991-04-16

    This patent describes a gravimetric cell for centrifugal separation of fine coal by density which has a cylindrical body and a butterfly valve or other apparatus for selectively sealing the body radially across the approximate center of the cylinder. A removable top is provided which seals the cylinder in the centrifuge and in unvented areas.

  8. 76 FR 50767 - In the Matter of USEC Inc., American Centrifuge Lead Cascade Facility, and American Centrifuge...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-08-16

    ...In the Matter of USEC Inc., American Centrifuge Lead Cascade Facility, and American Centrifuge Plant; Order Extending the Date by Which...SNM-7003 and SNM-2011 for the American Centrifuge Lead Cascade Facility (Lead...

  9. The Detection Rate of Molecular Gas in Elliptical Galaxies Constraints on Galaxy Formation Theories

    E-print Network

    Fujita, Y; Gouda, N; Fujita, Yutaka; Nagashima, Masahiro; Gouda, Naoteru

    2000-01-01

    In order to constrain parameters in galaxy formation theories, especially those for a star formation process, we investigate cold gas in elliptical galaxies. We calculate the detection rate of cold gas in them using a semi-analytic model of galaxy formation and compare it with observations. We show that the model with a long star formation time-scale (~20 Gyr) is inconsistent with observations. Thus, some mechanisms of reducing the mass of interstellar medium, such as the consumption of molecular gas by star formation and/or reheating from supernovae, are certainly effective in galaxies. Our model predicts that star formation induced when galaxies in a halo collide each other reduces the cold gas left until the present. However, we find that the reduction through random collisions of satellite (non-central) galaxies in mean free time-scale in a halo is not required to explain the observations. This may imply that the collisions and mergers between satellite galaxies do not occur so often in clusters or that t...

  10. ACCOUNTING CHOICE AND A THEORY OF CRISIS: THE CASES OF POST-PRIVATIZATION BRITISH TELECOM AND BRITISH GAS

    Microsoft Academic Search

    ANTHONY G. PUXTY

    1997-01-01

    In examining the accounting choices of two UK utilities, it is argued that positive accounting theory is devoid of explanatory power. In its place the paper proposes a neo-Marxist theory of crisis management, largely based on the work of Habermas. It analyses the financial statements of British Telecom and British Gas, and shows how their accounting choices may be more

  11. Gas-Kinetic Theory Based Flux Splitting Method for Ideal Magnetohydrodynamics

    NASA Technical Reports Server (NTRS)

    Xu, Kun

    1998-01-01

    A gas-kinetic solver is developed for the ideal magnetohydrodynamics (MHD) equations. The new scheme is based on the direct splitting of the flux function of the MHD equations with the inclusion of "particle" collisions in the transport process. Consequently, the artificial dissipation in the new scheme is much reduced in comparison with the MHD Flux Vector Splitting Scheme. At the same time, the new scheme is compared with the well-developed Roe-type MHD solver. It is concluded that the kinetic MHD scheme is more robust and efficient than the Roe- type method, and the accuracy is competitive. In this paper the general principle of splitting the macroscopic flux function based on the gas-kinetic theory is presented. The flux construction strategy may shed some light on the possible modification of AUSM- and CUSP-type schemes for the compressible Euler equations, as well as to the development of new schemes for a non-strictly hyperbolic system.

  12. Application of subgroup decomposition in diffusion theory to gas cooled thermal reactor problem

    SciTech Connect

    Yasseri, S.; Rahnema, F. [Nuclear and Radiological Engineering and Medical Physics Program, George W. Woodruff School, Georgia Institute of Technology, Atlanta, GA 30332-0405 (United States)

    2013-07-01

    In this paper, the accuracy and computational efficiency of the subgroup decomposition (SGD) method in diffusion theory is assessed in a ID benchmark problem characteristic of gas cooled thermal systems. This method can be viewed as a significant improvement in accuracy of standard coarse-group calculations used for VHTR whole core analysis in which core environmental effect and energy angle coupling are pronounced. It is shown that a 2-group SGD calculation reproduces fine-group (47) results with 1.5 to 6 times faster computational speed depending on the stabilizing schemes while it is as efficient as single standard 6-group diffusion calculation. (authors)

  13. Premixed and diffusion flames in a centrifuge

    SciTech Connect

    Durox, D.; Yuan, T.; Baillot, F. [Laboratoire d`Aerothermique du CNRS, Meudon (France)] [Laboratoire d`Aerothermique du CNRS, Meudon (France); Most, J.M. [Universite de Poitiers, Mignaloux-Beauvoir (France)] [Universite de Poitiers, Mignaloux-Beauvoir (France)

    1995-09-01

    Combustion experiments conducted in a centrifuge are rare, and the authors present results obtained during different tests campaigns. For premixed flames or for diffusion flames, two cases are distinguished--in one, small flames are steady, and in the other, tall flames may be sensitive to a natural instability created by buoyancy in burned gases. The results show that for premixed stationary flames, the flame shape is almost insensitive to buoyancy, except for a very light modification of the streamlines in burned and fresh gases due to the hydrodynamic effects. The physicochemistry of the flame front is not modified in the range of gravity levels studied (between 1g{sub 0} and 10 g{sub 0}). On the other hand, the morphology of stationary diffusion flames is strongly changed. Both flame height and surface area are reduced as gravity increases. A correlation with a theoretical model gives good agreement. Both diffusion and premixed flames oscillate vertically, at low frequency (of the order of about 10 Hz), if the flame height is sufficiently tall. This mechanism is created in the burned gas layer surrounding the flame, where buoyancy exerts an influence. The results show that the frequency increases with gravity intensity. The last part of the paper is devoted to the evaluation of the flow deflection in the burnt gases under the action of Coriolis force.

  14. Trace gas exchange and the validity of similarity theory in the roughness sublayer above forests

    NASA Astrophysics Data System (ADS)

    Simpson, Isobel Jane

    1997-11-01

    This thesis is an investigation of (1) methane (CH4) and nitrous oxide (N2O) exchange above a boreal aspen (Populus tremuloides) stand near Prince Albert, Saskatchewan, and (2) the similarity theory upon which the flux measurements were based. Although CH4 and N2O play significant roles in the atmosphere, estimates of their global source and sink strengths are only poorly constrained. Boreal ecosystems are a priority trace gas research area, and the CH4 and N2O exchanges were measured as part of the Boreal Ecosystem-Atmosphere Study (BOREAS). The fluxes were determined micrometeorologically using laser-based Trace Gas Analysis Systems (TGAS). Between April and September, 1994, a mean net CH4 emission of 15.7 ± 2.8 ng m-2 s-1 was measured from a tower above the aspen stand. The CH4 emissions peaked in late summer, and the CH4 flux and soil temperature correlated with r2 = 0.70. In contrast, CH4 uptake was recorded near the tower base. Overall, it appears that CH4 emissions from anoxic patches located throughout the above-canopy footprint overwhelmed uptake from drier areas to yield a net emission of CH4. The mean N2O emission of 1.4 ± 0.7 ng m-2 s-1 was attributable to low soil nitrate (NO3/sp-) and ammonium (NH4+) availability. The small CH4 and N2O fluxes required that they be determined using a flux-gradient approach based upon similarity theory. However, similarity theory has been reported to severely underestimate scalar fluxes in the roughness sublayer above forests. Accordingly, the validity of similarity theory was investigated above a mixed deciduous forest at Camp Borden, Ontario, between July and October 1995. The TGAS used in the research enabled a higher resolution measurement than has been previously possible in similarity theory investigations. Between 1.9 and 2.2 canopy heights (hc), the mean enhancement factor (the ratio of independent fluxes to similarity theory values) was 1.15 ± 0.07. Closer to the canopy (1.2 to 1.4 hc), mean enhancement factors of 1.61 ± 0.10 and 1.82 ± 0.11 were measured, before and after leaf senescence, respectively. Overall, it appears that similarity theory can be used within the roughness sublayer of forests with a greater confidence than previously has been believed.

  15. Sound generation in centrifugal compressors

    NASA Astrophysics Data System (ADS)

    Raitor, Till; Neise, Wolfgang

    2008-07-01

    An experimental study is described to explore the dominant sound generation mechanisms of the spectral components governing the overall noise level of centrifugal compressors. At the design speed with supersonic flow conditions in the rotor blade channels, blade tone noise and buzz-saw noise are the main contributors. On the inlet, rotor-alone noise is the main source while rotor-stator interaction noise dominates on the outlet side in case of vaned outlet diffusers. Over a large range of rotor speeds with subsonic flow conditions, radial compressor noise is dominated by tip clearance noise which is produced by the secondary flow through the gap between rotor blade tips and the casing wall which in turn gives rise to the rotating instability phenomena observed earlier in axial-flow machines.

  16. Centrifuges in gravitational physiology research

    NASA Technical Reports Server (NTRS)

    Ballard, Rodney W.; Davies, Phil; Fuller, Charles A.

    1993-01-01

    Data from space flight and ground based experiments have clearly demonstrated the importance of Earth gravity for normal physiological function in man and animals. Gravitational Physiology is concerned with the role and influence of gravity on physiological systems. Research in this field examines how we perceive and respond to gravity and the mechanisms underlying these responses. Inherent in our search for answers to these questions is the ability to alter gravity, which is not physically possible without leaving Earth. However, useful experimental paradigms have been to modify the perceived force of gravity by changing either the orientation of subjects to the gravity vector (i.e., postural changes) or by applying inertial forces to augment the magnitude of the gravity vector. The later technique has commonly been used by applying centripetal force via centrifugation.

  17. On reversal of centrifugal acceleration in special relativity

    E-print Network

    Maxim Lyutikov

    2009-03-05

    The basic principles of General Theory of Relativity historically have been tested in gedanken experiments in rotating frame of references. One of the key issues, which still evokes a lot of controversy, is the centrifugal acceleration. Machabeli & Rogava (1994) argued that centrifugal acceleration reverse direction for particles moving radially with relativistic velocities within a "bead on a wire" approximation. We show that this result is frame-dependent and reflects a special relativistic dilution of time (as correctly argued by de Felice (1995)) and is analogous to freezing of motion on the black hole horizon as seen by a remote observer. It is a reversal of coordinate acceleration; there is no such effect as measured by a defined set of observers, e.g., proper and/or comoving. Frame-independent velocity of a "bead" with respect to stationary rotating observers increases and formally reaches the speed of light on the light cylinder. In general relativity, centrifugal force does reverse its direction at photon circular orbit, r=3M in Schwarzschild metric, as argued by Abramowicz (1990).

  18. Centrifuge workers study. Phase II, completion report

    SciTech Connect

    Wooten, H.D.

    1994-09-01

    Phase II of the Centrifuge Workers Study was a follow-up to the Phase I efforts. The Phase I results had indicated a higher risk than expected among centrifuge workers for developing bladder cancer when compared with the risk in the general population for developing this same type of cancer. However, no specific agent could be identified as the causative agent for these bladder cancers. As the Phase II Report states, Phase I had been limited to workers who had the greatest potential for exposure to substances used in the centrifuge process. Phase II was designed to expand the survey to evaluate the health of all employees who had ever worked in Centrifuge Program Departments 1330-1339 but who had not been interviewed in Phase I. Employees in analytical laboratories and maintenance departments who provided support services for the Centrifuge Program were also included in Phase II. In December 1989, the Oak Ridge Associated Universities (ORAU), now known as Oak Ridge Institute for Science and Education (ORISE), was contracted to conduct a follow-up study (Phase II). Phase H of the Centrifuge Workers Study expanded the survey to include all former centrifuge workers who were not included in Phase I. ORISE was chosen because they had performed the Phase I tasks and summarized the corresponding survey data therefrom.

  19. Transport coefficients and resonances for a meson gas in Chiral Perturbation Theory

    E-print Network

    D. Fernandez-Fraile; A. Gomez Nicola

    2009-02-27

    We present recent results on a systematic method to calculate transport coefficients for a meson gas (in particular, we analyze a pion gas) at low temperatures in the context of Chiral Perturbation Theory (ChPT). Our method is based on the study of Feynman diagrams taking into account collisions in the plasma by means of the non-zero particle width. This implies a modification of the standard ChPT power counting scheme. We discuss the importance of unitarity, which allows for an accurate high energy description of scattering amplitudes, generating dynamically the $\\rho (770)$ and $f_0(600)$ mesons. Our results are compatible with analyses of kinetic theory, both in the non-relativistic very low-$T$ regime and near the transition. We show the behavior with temperature of the electrical and thermal conductivities as well as of the shear and bulk viscosities. We obtain that bulk viscosity is negligible against shear viscosity, except near the chiral phase transition where the conformal anomaly might induce larger bulk effects. Different asymptotic limits for transport coefficients, large-$N_c$ scaling and some applications to heavy-ion collisions are studied.

  20. Centrifuge polarizing microscope. II. Sample biological applications.

    PubMed

    Inoué, S; Goda, M; Knudson, R A

    2001-03-01

    The rationale, design and general performance of the CPM (centrifuge polarizing microscope) were described in Part I of this study (Inoué et al. J. Microsc. 201 (2001) 341-356. In this second part, we describe observations on several biological samples that we have explored over the past two years using the CPM. As described in the first part of the study, although the CPM was basically designed as a high-extinction centrifuge polarizing microscope, it also allows observations of the specimen exposed to high centrifugal fields up to 10 500 x g (earth's gravitational acceleration) in fluorescence (532-nm excitation) and in DIC (differential interference or Nomarski contrast). PMID:11240851

  1. Modeling of Centrifugal Force Field and the Effect on Filling and Solidification in Centrifugal Casting

    NASA Astrophysics Data System (ADS)

    Sheng, Wenbin; Ma, Chunxue; Gu, Wanli

    2011-06-01

    Based on the steady flow in a tube, a mathematical model has been established for the consideration of centrifuging force field by combining the equations of continuity, conservation of momentum and general energy. Effects of centrifugal field on the filling and solidification are modeled by two accessional terms: centrifugal force and Chorios force. In addition, the transfer of heat by convection is considered to achieve a coupling calculation of velocity field and temperature field. The solution of pressure item is avoided by introducing the stream function ?(x,y) and the eddy function ?(x,y). Corresponding difference formats for the simultaneous equations of centrifugal filling, the accessional terms and the solidifying latent heat have been established by the finite difference technique. Furthermore, the centrifugal filling and solidification processes in a horizontal tube are summarized to interpret the mechanism by which internal defects are formed in centrifugal castings.

  2. Paper No. : 0317 LATERAL SPREADING DURING CENTRIFUGE MODEL

    E-print Network

    Haigh, Stuart

    Paper No. : 0317 LATERAL SPREADING DURING CENTRIFUGE MODEL EARTHQUAKES Stuart K. Haigh1 , S sand marker lines within centrifuge models. A series of dynamic centrifuge model tests have been these free boundaries from previous earthquakes. Dynamic centrifuge modelling was carried out using sloping

  3. Effect of critical ionization rate in a plasma centrifuge

    NASA Astrophysics Data System (ADS)

    Korobtsev, S. V.; Medvedev, D. D.; Rakhimbabaev, Ia. R.; Rusanov, V. D.

    1989-12-01

    Experimental results are presented on effects manifested when the magnetic field in a plasma centrifuge approaches the critical value Bc, below which the proportionality between voltage on the discharge gap and the magnetic field strength breaks down. The value of Bc obtained significantly exceeds the limit values predicted by Brenning's (1985) theory. An increase in the critical rate was observed in the near-anode layer, whose thickness decreases with increasing magnetic field. A correlation between electron temperature and the presence of the critical-rate phenomenon was found.

  4. Application of Centrifugal Elutriation for aqueous suspension 

    E-print Network

    Ayers, Jeffrey Thomas

    1993-01-01

    Centrifugal Elutriation, a counter-flow separation method commonly used in the medical field to fractionate cells, was applied in the dynamic sorption and desorption studies for pentachlorophenol (PCP) associated with biotic (Chlorella pyrenoidosa...

  5. Centrifuge advances using HTS magnetic bearings

    NASA Astrophysics Data System (ADS)

    Werfel, F. N.; Flögel-Delor, U.; Rothfeld, R.; Wippich, D.; Riedel, T.

    2001-05-01

    Passive magnetic bearings are of increasing technical interest. We performed experiments with centrifugal rotors to analyze gyroscopic forces in terms imbalance, rotor elasticity and damping. Centrifuge rotors need to be operated soft and stable without whirling the sediments. In order to evaluate optimal parameters critical and resonance behaviors are investigated. Eccentricities up 2 mm are safely passed by accelerating test wheels. In a simple model we describe the effect of passing critical rotational speeds. Measurements of bearing properties and wheel performance are presented. We have constructed a first prototype centrifuge designed with a HTS double bearing which operates a titanium rotor safely up to 30 000 rpm. A 15 W Stirling cooler serves cryogenics of the YBCO stators. From the experiments design guidelines for centrifugal applications with HTS bearings are given.

  6. Microfluidic Centrifuge based on a Counterflow Configuration

    NASA Astrophysics Data System (ADS)

    Pertaya-Braun, Natalya; Baier, Tobias; Hardt, Steffen

    2011-03-01

    For many recent biotechnological applications it is of prime importance to be able to concentrate or separate small sample amounts. Developing a centrifugation technology that is compatible with lab-on-chip platforms will help reaching this goal and will allow integrating sample preparation with downstream analysis. Here we present a microfluidic centrifuge, designed without moving parts and relying on a vortex formed between two counterflowing liquid streams. The centrifuge is driven by streams with a speed of 1 - 5 m/s, and the acceleration applied to samples is 200 - 2000 g, depending on the size of the vortex, thus showing that such devices reach the same centrifugation power as commercially available ones. The liquid flow in the microcentrifuge chamber is visualized using fluorescent particles, and the ability for size dependent separation is clearly demonstrated.

  7. Improved return passages for multistage centrifugal compressors

    E-print Network

    Glass, Benjamin W., S.M. Massachusetts Institute of Technology

    2010-01-01

    This thesis presents a design concept for return passages in multistage centrifugal compressors. Flow in a baseline return passage is analyzed to identify loss sources that have substantial potential for reduction. For the ...

  8. A methodology for centrifugal compressor stability prediction

    E-print Network

    Benneke, Björn

    2009-01-01

    The stable operation of centrifugal compressors is limited by well-known phenomena, rotating stall and surge. Although the manifestation of the full scale instabilities is similar to the ones observed in axial machines, ...

  9. 21 CFR 864.5350 - Microsedimentation centrifuge.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES HEMATOLOGY AND PATHOLOGY DEVICES Automated and Semi-Automated Hematology Devices § 864.5350 Microsedimentation centrifuge. (a)...

  10. 21 CFR 864.5350 - Microsedimentation centrifuge.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES HEMATOLOGY AND PATHOLOGY DEVICES Automated and Semi-Automated Hematology Devices § 864.5350 Microsedimentation centrifuge. (a)...

  11. 21 CFR 864.5350 - Microsedimentation centrifuge.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES HEMATOLOGY AND PATHOLOGY DEVICES Automated and Semi-Automated Hematology Devices § 864.5350 Microsedimentation centrifuge. (a)...

  12. Design and experimental study of high-speed low-flow-rate centrifugal compressors

    SciTech Connect

    Gui, F.; Reinarts, T.R.; Scaringe, R.P. [Mainstream Engineering Corp., Rockledge, FL (United States); Gottschlich, J.M. [Air Force Wright Lab., Wright Patterson AFB, OH (United States)

    1995-12-31

    This paper describes a design and experimental effort to develop small centrifugal compressors for aircraft air cycle cooling systems and small vapor compression refrigeration systems (20--100 tons). Efficiency improvements at 25% are desired over current designs. Although centrifugal compressors possess excellent performance at high flow rates, low-flow-rate compressors do not have acceptable performance when designed using current approaches. The new compressors must be designed to operate at a high rotating speed to retain efficiency. The emergence of the magnetic bearing provides the possibility of developing such compressors that run at speeds several times higher than current dominating speeds. Several low-flow-rate centrifugal compressors, featured with three-dimensional blades, have been designed, manufactured and tested in this study. An experimental investigation of compressor flow characteristics and efficiency has been conducted to explore a theory for mini-centrifugal compressors. The effects of the overall impeller configuration, number of blades, and the rotational speed on compressor flow curve and efficiency have been studied. Efficiencies as high as 84% were obtained. The experimental results indicate that the current theory can still be used as a guide, but further development for the design of mini-centrifugal compressors is required.

  13. Centrifuge Safety A laboratory centrifuge can be an important tool in the university lab. It can also be a dangerous

    E-print Network

    de Lijser, Peter

    Centrifuge Safety A laboratory centrifuge can be an important tool in the university lab. It can with centrifugation stem from one of two sources: mechanical conditions, and processing hazardous materials for certain maximum speeds: KNOW THEM! · Always put on the lid and secure it. · Never open a centrifuge until

  14. Centrifuge Use There are a few important guidelines for operating a centrifuge, even a small one. Following them can

    E-print Network

    Kay, Mark A.

    Centrifuge Use There are a few important guidelines for operating a centrifuge, even a small one. Following them can prevent damage to the centrifuge and possible serious injury to you and others. Use 1. The work surface must be level and firm. Do not use the centrifuge on an uneven or slanted work surface. 2

  15. Centrifugation in water Drying in a 37 degree Celsius

    E-print Network

    Paris-Sud XI, Université de

    1 Centrifugation in water Drying in a 37 degree Celsius After some days the different phases were) CENTRIFUGATION CENTRIFUGATION 3 days in 40ml of water Then 20 ml of Butanol CENTRIFUGATION 3 days in 40 ml of 0.1 M Na OH Water. Then 20 ml of Butanol CENTRIFUGATION 3 days in 40 ml of HCL Water pH 5-6 Then 20 ml

  16. Centrifugal separation of antiprotons and electrons.

    PubMed

    Gabrielse, G; Kolthammer, W S; McConnell, R; Richerme, P; Wrubel, J; Kalra, R; Novitski, E; Grzonka, D; Oelert, W; Sefzick, T; Zielinski, M; Borbely, J S; Fitzakerley, D; George, M C; Hessels, E A; Storry, C H; Weel, M; Müllers, A; Walz, J; Speck, A

    2010-11-19

    Centrifugal separation of antiprotons and electrons is observed, the first such demonstration with particles that cannot be laser cooled or optically imaged. The spatial separation takes place during the electron cooling of trapped antiprotons, the only method available to produce cryogenic antiprotons for precision tests of fundamental symmetries and for cold antihydrogen studies. The centrifugal separation suggests a new approach for isolating low energy antiprotons and for producing a controlled mixture of antiprotons and electrons. PMID:21231298

  17. Improving the efficiency of centrifugal fans 

    E-print Network

    Wolfe, Clifford Kent

    1976-01-01

    IMPROVING THE EFFICIENCY OF CENTRIFUGAL FANS A Thesis by CLIFFORD KENT WOLFE Submitted to the Graduate College of Texas ARM University in partial fulfillment of the requirement for the degree of MASTER OF SCIENCE December 1976 Major... Subject: Mechanical Engineering IMPROVING THE EFFICIENCY OF CENTRIFUGAL FANS A. Thesis by CLIFFORD KENT WOLFE Approved as to sty1e and content by: : (Chairman of Committee / Head of Department +Me e Member December 1976 )&3&~ ABSTRACT...

  18. Improving the efficiency of centrifugal fans

    E-print Network

    Wolfe, Clifford Kent

    1976-01-01

    IMPROVING THE EFFICIENCY OF CENTRIFUGAL FANS A Thesis by CLIFFORD KENT WOLFE Submitted to the Graduate College of Texas ARM University in partial fulfillment of the requirement for the degree of MASTER OF SCIENCE December 1976 Major... Subject: Mechanical Engineering IMPROVING THE EFFICIENCY OF CENTRIFUGAL FANS A. Thesis by CLIFFORD KENT WOLFE Approved as to sty1e and content by: : (Chairman of Committee / Head of Department +Me e Member December 1976 )&3&~ ABSTRACT...

  19. Viscous flow prediction within a centrifugal impeller 

    E-print Network

    Wohlschlegel, David Hale

    1976-01-01

    of impeller u kinematic viscosity S~b' t meridional component radial component component in direction of boundary layer component perpendicular to boundary layer axial component free stream value CHAPTER I INTRODUCTION The centrifugal compressor... Journal. and the locations of rapid velocity changes, which indicate a boundary layer separation, may be found. The flow within a centrifugal compressor is extremely difficult to predict since it has curvature from the axial to the radial direction...

  20. Renal Response to Chronic Centrifugation in Rats

    NASA Technical Reports Server (NTRS)

    Ortiz, Rudy M.; Wang, T. J.; Corbin, B. J.; Wade, C. E.; Hargens, Alan R. (Technical Monitor)

    1996-01-01

    Previously reported effects of chronic centrifugation on renal function in mammals are contradictory. The present study was conducted as an effort to provide a comprehensive analysis of renal response to chronic centrifugation (12 days at +2 Gz). Sixteen male Sprague-Dawley rats (210-230 g) were used: eight centrifuged (EC) and eight off centrifuge controls (OCC). During centrifugation EC had lower body weight and food consumption. EC showed a decrease (72%) in water intake for the first two days (T1 and T2) followed by significant increases from T4-T6. EC urine output increased two-fold over the first four days, returning to baseline by T9. EC urea excretion was elevated on T3 through T5. Creatinine, Na(+), K(+), and osmolar excretion were lower than OCC over the last four days of the study. Assuming constant plasma osmolarity and creatinine levels, EC free water clearance (C(sub H2O)) was elevated significantly on T4 when the peak urine output was exhibited. EC also had a greater C(sub H2O) over the last four days, associated with a significantly lower osmolar clearance and GFR. The initial diuresis exhibited during centrifugation can be attributed to a reduced water resorption and increased urea excretion. This diuresis was mediated independent of changes in GFR over the first eight days. However, differences in excretion seen after eight days of centrifugation are probably GFR mediated which would imply animals established a new homeostatic setpoint by that time. Centrifugation elicites an acute alteration in fluid homeostasis followed by adaptation within a week.

  1. Combination Of Investment And Centrifugal Casting

    NASA Technical Reports Server (NTRS)

    Creeger, Gordon A.

    1994-01-01

    Modifications, including incorporation of centrifugal casting, made in investment-casting process reducing scrap rate. Used to make first- and second-stage high-pressure-fuel-turbopump nozzles, containing vanes with thin trailing edges and other thin sections. Investment mold spun for short time while being filled, and stopped before solidification occurs. Centrifugal force drives molten metal into thin trailing edges, ensuring they are filled. With improved filling, preheat and pour temperatures reduced and solidification hastened so less hot tearing.

  2. Isolation of symbiotic dinoflagellates by centrifugal elutriation

    SciTech Connect

    Bird, A.E.; Quinn, R.J.

    1986-01-01

    Centrifugal elutriation, a method combining centripetal liquid flow with centrifugal force, has been used to isolate symbiotic dinoflagellates from a cnidarian host. The elutriated cells were shown to be viable by photosynthetic incorporation of /sup 14/CO/sub 2/ and low release of photosynthetic products into the incubation medium. The level of contamination by clinging debris was low and by host solids was negligible.

  3. Gas Clouds in Whirlpool Galaxy Yield Important Clues Supporting Theory on Spiral Arms

    NASA Astrophysics Data System (ADS)

    2004-06-01

    Astronomers studying gas clouds in the famous Whirlpool Galaxy have found important clues supporting a theory that seeks to explain how the spectacular spiral arms of galaxies can persist for billions of years. The astronomers applied techniques used to study similar gas clouds in our own Milky Way to those in the spiral arms of a neighbor galaxy for the first time, and their results bolster a theory first proposed in 1964. M51 The spiral galaxy M51: Left, as seen with the Hubble Space Telescope; Right, radio image showing location of Carbon Monoxide gas. CREDIT: STScI, OVRO, IRAM (Click on image for larger version) Image Files Optical and Radio (CO) Views (above image) HST Optical Image with CO Contours Overlaid Radio/Optical Composite Image of M51 VLA/Effelsberg Radio Image of M51, With Panel Showing Magnetic Field Lines The Whirlpool Galaxy, about 31 million light-years distant, is a beautiful spiral in the constellation Canes Venatici. Also known as M51, it is seen nearly face-on from Earth and is familiar to amateur astronomers and has been featured in countless posters, books and magazine articles. "This galaxy made a great target for our study of spiral arms and how star formation works along them," said Eva Schinnerer, of the National Radio Astronomy Observatory in Socorro, NM. "It was ideal for us because it's one of the closest face-on spirals in the sky," she added. Schinnerer worked with Axel Weiss of the Institute for Millimeter Radio Astronomy (IRAM) in Spain, Susanne Aalto of the Onsala Space Observatory in Sweden, and Nick Scoville of Caltech. The astronomers presented their findings to the American Astronomical Society's meeting in Denver, Colorado. The scientists analyzed radio emission from Carbon Monoxide (CO) molecules in giant gas clouds along M51's spiral arms. Using telescopes at Caltech's Owens Valley Radio Observatory and the 30-meter radio telescope of IRAM, they were able to determine the temperatures and amounts of turbulence within the clouds. Their results provide strong support for a theory that "density waves" explain how spiral arms can persist in a galaxy without winding themselves so tightly that, in effect, they disappear. The density-wave theory, proposed by Frank Shu and C.C. Lin in 1964, says that a galaxy's spiral pattern is a wave of higher density, or compression, that revolves around the galaxy at a speed different from that of the galaxy's gas and stars. Schinnerer and her colleagues studied a region in one of M51's spiral arms that presumably has just overtaken and passed through the density wave. Their data indicate that gas on the trailing edge of the spiral arm, which has most recently passed through the density wave, is both warmer and more turbulent than gas in the forward edge of the arm, which would have passed through the density wave longer ago. "This is what we would expect from the density-wave theory," Schinnerer said. "The gas that passed through the density wave earlier has had time to cool and lose the turbulence caused by the passage," she added. "Our results show, for the first time, how the density wave operates on a cloud-cloud scale, and how it promotes and prevents star formation in spiral arms," Aalto said. The next step, the scientists say, is to look at other spiral galaxies to see if a similar pattern is present. That will have to wait, Schinnerer said, because the radio emission from CO molecules that provides the information on temperature and turbulence is very faint. "When the Atacama Large Millimeter Array (ALMA) comes on line, it will have the ability to extend this type of study to other galaxies. We look forward to using ALMA to test the density-wave model more thoroughly," Schinnerer said. ALMA is a millimeter-wave observatory that will use 64, 12-meter-diameter dish antennas on the Atacama Desert of northern Chile. Now under construction, ALMA will provide astronomers with an unprecedented capability to study the Universe at millimeter wavelengths. The Whirlpool Galaxy was

  4. Gas and solute diffusion in partially saturated porous media: Percolation theory and Effective Medium Approximation compared with lattice Boltzmann simulations

    NASA Astrophysics Data System (ADS)

    Ghanbarian, Behzad; Daigle, Hugh; Hunt, Allen G.; Ewing, Robert P.; Sahimi, Muhammad

    2015-01-01

    Understanding and accurate prediction of gas or liquid phase (solute) diffusion are essential to accurate prediction of contaminant transport in partially saturated porous media. In this study, we propose analytical equations, using concepts from percolation theory and the Effective Medium Approximation (EMA) to model the saturation dependence of both gas and solute diffusion in porous media. The predictions of our theoretical approach agree well with the results of nine lattice Boltzmann simulations. We find that the universal quadratic scaling predicted by percolation theory, combined with the universal linear scaling predicted by the EMA, describes diffusion in porous media with both relatively broad and extremely narrow pore size distributions.

  5. Extended Chaplygin gas as a unified fluid of dark components in varying gravitational constant theory

    NASA Astrophysics Data System (ADS)

    Lu, Jianbo; Xu, Lixin; Tan, Hongyan; Gao, Shanshan

    2014-03-01

    Varying gravitational constant G(t) (VG) cosmology is studied in this paper, where the modified Friedmann equation and the modified energy conservation equation are given with respect to the constant-G theory. Considering the extended Chaplygin gas (ECG) as background fluid (or thinking that ECG fluid is induced by the variation of G), the unified model of dark matter and dark energy is obtained in VG theory. The parameter spaces are investigated in the VG-ECG model by using the recent cosmic data. Constraint results show ? =-G/.HG =-0.003-0.020-0.055+0.021+0.034 for the VG-GCG unified model and ?=-0.027-0.032-0.066+0.032+0.059 for the VG-MCG unified model. Equivalently, they correspond to the limits on the current variation of Newton's gravitational constant at 95.4% confidence level |G/.G|today?4.1×10-12 yr-1 and |G/.G|today?6.6×10-12 yr-1. And for z ?3.5, bounds on the variation of G/.G in the VG-ECG unified model are in accordance with the experiment explorations of varying G. In addition, in VG theory the used observational data point still cannot distinguish the VG-GCG and VG-MCG unified model from the most popular ?CDM cosmology. Furthermore, to see the effects of varying G and physical properties for VG-ECG fluid, we discuss the evolutionary behaviors of cosmological quantities in VG theory, such as G/.G, G./.G and equation of state w, etc. For ? <0 a quintom scenario crossing over w=-1 can be realized in the VG-GCG model.

  6. Two-Stage Centrifugal Fan

    NASA Technical Reports Server (NTRS)

    Converse, David

    2011-01-01

    Fan designs are often constrained by envelope, rotational speed, weight, and power. Aerodynamic performance and motor electrical performance are heavily influenced by rotational speed. The fan used in this work is at a practical limit for rotational speed due to motor performance characteristics, and there is no more space available in the packaging for a larger fan. The pressure rise requirements keep growing. The way to ordinarily accommodate a higher DP is to spin faster or grow the fan rotor diameter. The invention is to put two radially oriented stages on a single disk. Flow enters the first stage from the center; energy is imparted to the flow in the first stage blades, the flow is redirected some amount opposite to the direction of rotation in the fixed stators, and more energy is imparted to the flow in the second- stage blades. Without increasing either rotational speed or disk diameter, it is believed that as much as 50 percent more DP can be achieved with this design than with an ordinary, single-stage centrifugal design. This invention is useful primarily for fans having relatively low flow rates with relatively high pressure rise requirements.

  7. Second-order fluid dynamics for the unitary Fermi gas from kinetic theory

    NASA Astrophysics Data System (ADS)

    Schäfer, Thomas

    2014-10-01

    We compute second-order transport coefficients of the dilute Fermi gas at unitarity. The calculation is based on kinetic theory and the Boltzmann equation at second order in the Knudsen expansion. The second-order transport coefficients describe the shear stress relaxation time, nonlinear terms in the strain-stress relation, and nonlinear couplings between vorticity and strain. An exact calculation in the dilute limit gives ?R=? /P , where ?R is the shear stress relaxation time, ? is the shear viscosity, and P is pressure. This relation is identical to the result obtained using the Bhatnagar-Gross-Krook approximation to the collision term, but other transport coefficients are sensitive to the exact collision integral.

  8. Prototyping of ultra micro centrifugal compressor-influence of meridional configuration

    NASA Astrophysics Data System (ADS)

    Hirano, Toshiyuki; Muto, Tadataka; Tsujita, Hoshio

    2011-08-01

    In order to investigate the design method for a micro centrifugal compressor, which is the most important component of an ultra micro gas turbine, two types of centrifugal impeller with 2-dimensional blade were designed, manufactured and tested. These impellers have different shapes of hub on the meridional plane with each other. Moreover, these types of impeller were made for the 5 times and the 6 times size of the final target centrifugal impeller with the outer diameter of 4mm in order to assess the similitude for the impellers. The comparison among the performance characteristics of the impellers revealed the influence of the meridional configuration on the performance and the similitude of the compressors.

  9. Deformation of antisymmetric laminate under centrifugal force and\\/or thermal load

    Microsoft Academic Search

    Fenghua Zhou; Akinori Ogawa; Ryosaku Hashimoto

    2001-01-01

    A smart blade conception has been proposed by the authors. With stretching–twisting coupling effect, the blade is twisted by centrifugal load or ambient temperature change. In this paper, the blade, simplified as a cantilevered antisymmetric laminate, is investigated by classic plate theory. An analytical scheme based on Rayleigh–Ritz (RR) method is proposed to calculate plate's deformation behavior. RR's analytical results

  10. Weak rotating flow disturbances in a centrifugal compressor with a vaneless diffuser

    Microsoft Academic Search

    F. K. Moore

    1988-01-01

    A theory is presented to predict the occurrence of weak rotating waves in a centrifugal compression system with a vaneless diffuser. As in a previous study of axial systems, an undisturbed performance characteristic is assumed known. Following an inviscid analysis of the diffuser flow, conditions for a neutral rotating disturbance are found. The solution is shown to have two branches;

  11. Importance of centrifugal effects for the internal kink mode stability in toroidally rotating tokamak plasmas

    SciTech Connect

    Wahlberg, C. [Department of Physics and Astronomy, EURATOM/VR Fusion Association, Uppsala University, P.O. Box 516, SE-751 20 Uppsala (Sweden); Chapman, I. T. [EURATOM/CCFE Fusion Association, Culham Science Centre, Abingdon, Oxfordshire OX14 3DB (United Kingdom); Graves, J. P. [Centre de Recherches en Physique des Plasmas, Association EURATOM-Confederation Suisse, EPFL, 1015 Lausanne (Switzerland)

    2009-11-15

    Analytical theory and two different magnetohydrodynamical stability codes are used in a study of the effects of toroidal plasma rotation on the stability of the ideal, internal kink mode in tokamaks. The focus of the paper is on the role that the centrifugal effects on the plasma equilibrium play for the stability of this mode, and results from one code where centrifugal effects are self-consistently included (CASTOR-FLOW) [E. Strumberger et al., Nucl. Fusion 45, 1156 (2005)] are compared with the results from another code where such effects are not taken into account (MISHKA-F) [I. T. Chapman et al., Phys. Plasmas 13, 062511 (2006)]. It is found that, even at rather modest flow speeds, the centrifugal effects are very important for the stability of the internal kink mode. While the results from the two codes can be quite similar for certain profiles in the plasma, completely opposite results are obtained for other profiles. A very good agreement between analytical theory and the numerical results are, both for inconsistent and consistent equilibria, found for plasmas with large aspect ratio. From the analytical theory, the distinctly different stability properties of equilibria with and without centrifugal effects included can be traced to the stabilizing effect of the geodesic acoustic mode (GAM) induced by the plasma rotation. This GAM exists solely as a consequence of the nonuniform plasma density and pressure created by the centrifugal force on the flux surfaces, and a stabilizing coupling of the internal kink instability to this mode cannot therefore take place if the centrifugal effects are not included in the equilibrium. In addition to the GAM stabilization, the effects of the radial profiles of the plasma density and rotation velocity are also found to be significant, and the importance of these effects increases with decreasing aspect ratio.

  12. Boundary-driven nonequilibrium gas flow in a grooved channel via kinetic theory

    NASA Astrophysics Data System (ADS)

    Naris, Steryios; Valougeorgis, Dimitris

    2007-06-01

    The nonequilibrium flow of a gas in a two-dimensional grooved channel, due to the motion of the wall of the channel, is investigated based on kinetic theory. The presence of the rectangular grooves that are placed periodically on the stationary wall results in a two-dimensional flow pattern. The problem is modeled by the linearized Bhatnagar-Gross-Krook (BGK) and S-model kinetic equations, which are solved for the corresponding perturbed distribution functions by the discrete velocity method. Maxwell diffuse type reflecting boundary conditions are used to model the gas-surface interaction, while periodic boundary conditions are imposed at the inlet and outlet of the channel. The computed macroscopic quantities of practical interest include velocity profiles, contours of pressure, density, and temperature, as well as the flow rate and the heat flux through the channel and the drag coefficient along the moving boundary. The results are valid in the whole range of the Knudsen number, from the free molecular regime through the transition and slip regimes up to the hydrodynamic limit, for various values of the depth and the width of the groove and the periodic length of the channel. A comparison between the BGK and S-model results is performed. Several interesting flow patterns and characteristics are examined in terms of the geometrical parameters of the flow configuration, including an unexpected behavior of the velocity profile across the channel at large Knudsen numbers.

  13. Investigation of the Aerodynamic Drag of an Eight-Channel Centrifugal Filter

    NASA Astrophysics Data System (ADS)

    Serebryanskii, D. A.; Semenyuk, N. S.; Plashikhin, S. V.

    2015-03-01

    The aerodynamic characteristics and the structure of vortices of the central region of the channel system of an eight-channel centrifugal filter have been investigated. An overview of the foreign and home literature on the filtration of solid particles in the gas flow in centrifugal apparatuses is given [1, 2]. We present the design and the principle of operation of the eight-channel centrifugal filter based on a system of curvilinear channels with equal turn angles and equal cross-sectional areas connected in series. We have performed numerical calculations of the dependence of the aerodynamic drag of the centrifugal filter on the rate of fl ow obtained by three different methods: analytical calculation, experiments on the laboratory facility, and with the help of modern means of computer modeling. Computational modeling of the flow was carried out by solving Reynolds (RANS, Reynolds-averaged Navier-Stokes) equations by the SFD method with the use of a k-? model of turbulence for three modes of operation of the apparatus. The results of computer modeling permitted visualizing the vortex structure of the central region of the separation chamber in the form of 3D graphs. The obtained results have been confirmed experimentally on a laboratory model of the centrifugal filter of capacity up to 200 m3/h of purified air.

  14. Kinetic theory for a mobile impurity in a degenerate Tonks-Girardeau gas.

    PubMed

    Gamayun, O; Lychkovskiy, O; Cheianov, V

    2014-09-01

    A kinetic theory describing the motion of an impurity particle in a degenerate Tonks-Girardeau gas is presented. The theory is based on the one-dimensional Boltzmann equation. An iterative procedure for solving this equation is proposed, leading to the exact solution in a number of special cases and to an approximate solution with the explicitly specified precision in a general case. Previously we reported that the impurity reaches a nonthermal steady state, characterized by an impurity momentum p(?) depending on its initial momentum p(0) [E. Burovski, V. Cheianov, O. Gamayun, and O. Lychkovskiy, Phys. Rev. A 89, 041601(R) (2014)]. In the present paper the detailed derivation of p(?)(p(0)) is provided. We also study the motion of an impurity under the action of a constant force F. It is demonstrated that if the impurity is heavier than the host particles, m(i)>m(h), damped oscillations of the impurity momentum develop, while in the opposite case, m(i)

  15. Centrifugal separation and equilibration dynamics in an electron-antiproton plasma.

    PubMed

    Andresen, G B; Ashkezari, M D; Baquero-Ruiz, M; Bertsche, W; Bowe, P D; Butler, E; Cesar, C L; Chapman, S; Charlton, M; Deller, A; Eriksson, S; Fajans, J; Friesen, T; Fujiwara, M C; Gill, D R; Gutierrez, A; Hangst, J S; Hardy, W N; Hayden, M E; Humphries, A J; Hydomako, R; Jonsell, S; Madsen, N; Menary, S; Nolan, P; Olin, A; Povilus, A; Pusa, P; Robicheaux, F; Sarid, E; Silveira, D M; So, C; Storey, J W; Thompson, R I; van der Werf, D P; Wurtele, J S; Yamazaki, Y

    2011-04-01

    Charges in cold, multiple-species, non-neutral plasmas separate radially by mass, forming centrifugally separated states. Here, we report the first detailed measurements of such states in an electron-antiproton plasma, and the first observations of the separation dynamics in any centrifugally separated system. While the observed equilibrium states are expected and in agreement with theory, the equilibration time is approximately constant over a wide range of parameters, a surprising and as yet unexplained result. Electron-antiproton plasmas play a crucial role in antihydrogen trapping experiments. PMID:21561196

  16. Centrifugal separation and equilibration dynamics in an electron-antiproton plasma

    E-print Network

    Andresen, G B; Baquero-Ruiz, Marcelo; Bertsche, William; Bowe, Paul D; Butler, Eoin; Cesar, Claudio L; Chapman, Steven; Charlton, Michael; Deller, A; Eriksson, S; Fajans, Joel; Friesen, Tim; Fujiwara, Makoto C; Gill, David R; Gutierrez, A; Hangst, Jeffrey S; Hardy, Walter N; Hayden, Michael E; Humphries, Andrew J; Hydomako, Richard; Jonsell, Svante; Madsen, Niels; Menary, Scott; Nolan, Paul; Olin, Art; Povilus, Alexander; Pusa, Petteri; Robicheaux, Francis; Sarid, Eli; Silveira, Daniel M; So, Chukman; Storey, James W; Thompson, Robert I; van der Werf, Dirk P; Wurtele, Jonathan S; Yamazaki, Yasunori

    2011-01-01

    Charges in cold, multiple-species, non-neutral plasmas separate radially by mass, forming centrifugally-separated states. Here, we report the first detailed measurements of such states in an electron-antiproton plasma, and the first observations of the separation dynamics in any centrifugally-separated system. While the observed equilibrium states are expected and in agreement with theory, the equilibration time is approximately constant over a wide range of parameters, a surprising and as yet unexplained result. Electron-antiproton plasmas play a crucial role in antihydrogen trapping experiments.

  17. Centrifugal separation and equilibration dynamics in an electron-antiproton plasma

    E-print Network

    G. B. Andresen; M. D. Ashkezari; M. Baquero-Ruiz; W. Bertsche; P. D. Bowe; E. Butler; C. L. Cesar; S. Chapman; M. Charlton; A. Deller; S. Eriksson; J. Fajans; T. Friesen; M. C. Fujiwara; D. R. Gill; A. Gutierrez; J. S. Hangst; W. N. Hardy; M. E. Hayden; A. J. Humphries; R. Hydomako; S. Jonsell; N. Madsen; S. Menary; P. Nolan; A. Olin; A. Povilus; P. Pusa; F. Robicheaux; E. Sarid; D. M. Silveira; C. So; J. W. Storey; R. I. Thompson; D. P. van der Werf; J. S. Wurtele; Y. Yamazaki

    2011-04-26

    Charges in cold, multiple-species, non-neutral plasmas separate radially by mass, forming centrifugally-separated states. Here, we report the first detailed measurements of such states in an electron-antiproton plasma, and the first observations of the separation dynamics in any centrifugally-separated system. While the observed equilibrium states are expected and in agreement with theory, the equilibration time is approximately constant over a wide range of parameters, a surprising and as yet unexplained result. Electron-antiproton plasmas play a crucial role in antihydrogen trapping experiments.

  18. Centrifugally cast bimetallic pipe for offshore corrosion resistant pipelines

    SciTech Connect

    Yoshitake, A.; Torigoe, T. [Kubota Corp., Hirakata (Japan)

    1994-12-31

    Centrifugally cast bimetallic pipes and fittings have been developed for the use of offshore oil and gas production. The metallurgical properties, mechanical properties, and corrosion properties of centrifugal a cast bimetallic pipe with outside metal of API 5L X52 to X65 internally clad with alloy 825 and 625 are discussed. First, molten steel for outer pipe is introduced into a rotating metallic mold. During the solidification of the outer pipe (carbon steel), the temperature of the pipe inside is monitored. After the solidification of the outer pipe, and when a certain temperature is reached, then a corrosion resistant alloy such as Alloy 825 or 625 for inside layer is poured. By controlling the casting conditions and selecting suitable flux, sound metallurgical bonded bimetallic pipe is produced with a minimum mixing layer at the interface also keeping a homogeneous outside wall thickness along the pipe length. The weld joints of the pipe are also evaluated from the view points of weldability, mechanical strength, fracture toughness, and corrosion resistance properties. The welding method applied was basically TIG welding (GTAW). COD tests at {minus}10 C are applied to the welds to investigate fracture toughness of the weld joints. Huey test according to ASTM A262C is carried out on the root of the welds as the corrosion test. As a result, the weld joint using filler wire of alloy625 from root to cover pass has proved a very reliable method from the point of view of mechanical and corrosion resistance properties. These centrifugally cast bimetallic pipes and fittings have been widely used for riser pipes, template process lines, top side and subsea manifolds, and flow bends for christmas trees in the North Sea.

  19. Enhanced infectivity of bluetongue virus in cell culture by centrifugation.

    PubMed Central

    Sundin, D R; Mecham, J O

    1989-01-01

    The effects of centrifugation of the infection of cell culture with bluetongue virus (BTV) were investigated. Baby hamster kidney cells were infected with BTV with or without centrifugation. Viral antigen was detected by immunofluorescence at 24 h in both centrifuged and noncentrifuged cultures. However, after 24 h of infection, the production of PFU in centrifuged cell cultures was 10- to 20-fold greater than that seen in cultures not centrifuged. In addition, centrifugation enhanced the direct detection of PFU from blood samples collected from a sheep experimentally infected with BTV. Images PMID:2549092

  20. Stop-motion illuminator for centrifuges

    NASA Astrophysics Data System (ADS)

    Moroz, Pavel E.

    1999-11-01

    The majority of laboratory centrifuges have no provisions for observation of the process of sedimentation and fractionation which goes on in the test tube in the darkness of a "black box." Some centrifuges have a transparent cover or a magnifier in the cover to watch a blurred picture of the layers in the moving test tube which provides little information. The stop-motion effect with the test tube can a priori be based on either mechanical or electronic stroboscopy. To implement the mechanical stroboscopy, a standard microscope illuminator with a diaphragm is attached to the wall of the centrifuge. Through a hole in the wall the illuminator projects a cone of light with the diameter 0.1 mm at the top of the cone. The cone intersects with a 0.1 mm hole in the test-tube holder. The test tube is illuminated at the moment of intersection. Its content is observed through a magnifier on the cover of the centrifuge. The holder has a cut-out window to see the test tube. The flash at the hole-beam intersection is 0.5 ?s, which is many times shorter than the duration of a xenon-tube stroboscopic flash (10-20 ?s). This is the main reason why industrial stroboscopes cannot be used for stop-motion illumination in a centrifuge.

  1. Liquid centrifugation for nuclear waste partitioning

    SciTech Connect

    Bowman, C.D.

    1992-03-11

    The performance of liquid centrifugation for nuclear waste partitioning is examined for the Accelerator Transmutation of Waste Program currently under study at the Los Alamos National Laboratory. Centrifugation might have application for the separation of the LiF-BeF{sub 2} salt from heavier radioactive materials fission product and actinides in the separation of fission product from actinides, in the isotope separation of fission-product cesium before transmutation of the {sup 137}Cs and {sup 135}Cs, and in the removal of spallation product from the liquid lead target. It is found that useful chemical separations should be possible using existing materials for the centrifuge construction for all four cases with the actinide fraction in fission product perhaps as low as 1 part in 10{sup 7} and the fraction of {sup 137}CS in {sup 133}Cs being as low as a few parts in 10{sup 5}. A centrifuge cascade has the advantage that it can be assembled and operated as a completely closed system without a waste stream except that associated with maintenance or replacement of centrifuge components.

  2. Possible segregation caused by centrifugal titanium casting.

    PubMed

    Watanabe, K; Okawa, S; Kanatani, M; Nakano, S; Miyakawa, O; Kobayashi, M

    1996-12-01

    The possibility of the segregation under solidification process using a centrifugal casting machine was investigated using an electron probe microanalyzer with elemental distribution map, line analysis and quantitative analysis. When a very small quantity of platinum was added to local molten titanium during the casting process, macroscopic segregation was observed under conditions of density difference of 0.1 g/cm3 at the most, confirming that the centrifugal force of the casting machine is extremely strong. When a Ti-6Al-4V alloy was cast, however, no macroscopic segregation was observed. The centrifugal force of the casting machine examined in the present study hardly results in the body-force segregation in this titanium alloy. PMID:9550020

  3. Centrifugal compressor design for electrically assisted boost

    NASA Astrophysics Data System (ADS)

    Y Yang, M.; Martinez-Botas, R. F.; Zhuge, W. L.; Qureshi, U.; Richards, B.

    2013-12-01

    Electrically assisted boost is a prominent method to solve the issues of transient lag in turbocharger and remains an optimized operation condition for a compressor due to decoupling from turbine. Usually a centrifugal compressor for gasoline engine boosting is operated at high rotational speed which is beyond the ability of an electric motor in market. In this paper a centrifugal compressor with rotational speed as 120k RPM and pressure ratio as 2.0 is specially developed for electrically assisted boost. A centrifugal compressor including the impeller, vaneless diffuser and the volute is designed by meanline method followed by 3D detailed design. Then CFD method is employed to predict as well as analyse the performance of the design compressor. The results show that the pressure ratio and efficiency at design point is 2.07 and 78% specifically.

  4. The geotechnical centrifuge in offshore engineering

    SciTech Connect

    Murff, J.D.

    1996-12-31

    One of the greatest needs in offshore geotechnical engineering is for large scale test measurements on which to calibrate design procedures. The geotechnical centrifuge offers at least a partial remedy. Because it allows one to properly simulate stresses, it is a legitimate, relatively inexpensive option to full scale field testing. As such it is a valuable technique and can be an excellent complement to laboratory tests, 1-g model tests and numerical analyses. However, it has not been widely used by industry even though the capability has existed for almost thirty years. This paper argues that this technology should gain acceptance beyond the research community. The paper presents an overview of centrifuge principles, philosophies of use, and limitations of the technique. For illustration, several actual applications of centrifuge testing for complex offshore problems are described. Results are shown to provide important insights into prototype behavior and to agree well with full scale measurements where these are available.

  5. Effects of chronic centrifugation on mice

    NASA Technical Reports Server (NTRS)

    Janer, L.; Duke, J.

    1984-01-01

    Previous studies have shown that exposure to excess gravity in vitro alters the developmental sequence in embryonic mouse limbs and palates (Duke, Janer and Campbell, 1984; Duke, 1983). The effects of excess gravity on in vivo mammalian development was investigated using a small animal centrifuge. Four-week old female mice exposed to excess gravities of 1.8-3.5 G for eight weeks weighed significantly less than controls. Mice were mated after five weeks of adaptation to excess G, and sacrificed either at gestational day 12 or 18. There were fewer pregnancies in the centrifuged group (4/36) than in controls (9/31), and crown rump lengths (CRL) of embryos developing in the centrifuge were less than CRLs of 1-G embryos. These results show that although immersed in amniotic fluid, embryos are responsive to Delta-G.

  6. Effects of Centrifuge Diameter and Operation on Rodent Adaptation to Chronic Centrifugation

    NASA Technical Reports Server (NTRS)

    Fuller, Charles A.

    1997-01-01

    This study examined the responses of rats to centrifugation in a constant acceleration field (1.5 G). Centrifuge diameter (1.8m, 2.5m or 6.0m) and schedule of operation (Daily or weekly stop) varied between groups. Body mass, food consumption, water consumption and neurovestibular function were measured weekly. Body temperature and activity were continuously monitored using telemetry. A subset of subjects were videotaped (50 minutes per day) to allow for movement analysis. Exposure to a hyperdynamic field of this magnitude did cause the expected depression in the physiological variables monitored. Recovery was accomplished within a relatively rapid time frame; all variables returned to precentrifugation levels. In general, the magnitudes of the changes and the rate of recovery were similar at different centrifuge diameters and stopping frequency. There were cases, however, in which the magnitude of the response and/or the rate of recovery to a new steady-state were altered as a result of centrifuge diameter. In summary, these results indicate that stopping frequency has little, if any, effect on adaptation to chronic centrifugation. However, the angular velocity (omega), and therefore centrifuge diameter is an important consideration in the adaptation of an organism to chronic centrifugation.

  7. Effects of Centrifuge Diameter and Operation on Rodent Adaptation to Chronic Centrifugation

    NASA Technical Reports Server (NTRS)

    Fuller, Charles A.

    1992-01-01

    This study examined the responses of rats to centrifugation in a constant acceleration field (1.5 G). Centrifuge diameter (1.8m, 2.5m or 6.0m) and schedule of operation (Daily or weekly stop) varied between groups. Body mass, food consumption, water consumption and neurovestibular function were measured weekly. Body temperature and activity were continuously monitored using telemetry. A subset of subjects were videotaped (50 minutes per day) to allow for movement analysis. Exposure to a hyperdynamic field of this magnitude did cause the expected depression in the physiological variables monitored. Recovery was accomplished within a relatively rapid time frame; all variables returned to precentrifugation levels. In general, the magnitudes of the changes and the rate of recovery were similar at different centrifuge diameters and stopping frequency. There were cases, however, in which the magnitude of the response and/or the rate of recovery to a new steady-state were altered as a result of centrifuge diameter. In summary, these results indicate that stopping frequency has little, if any, effect on adaptation to chronic centrifugation. However, the angular velocity (omega), and therefore centrifuge diameter is an important consideration in the adaptation of an organism to chronic centrifugation.

  8. Experiment and Theory for the Thickness Effect of Nano Metal Oxide Gas Sensing Thin Film The Thickness Effect and Mesoscopic Theory of Conductance Activity Energy

    Microsoft Academic Search

    Xing Jianping; Yuan Qinghua; Li Donghua; Lu Honglang; Qiu Nanwan

    2006-01-01

    The characteristics of conductance activity energy of SnO2 thin film varies with film thickness l and grain size r0 are given by experiment results. The cross-section current formula of porous materials and the conductance formula of gas sensing thin film with adsorbed oxygen negative ion are given. The mesoscopic theory of nano-thin film conductance activity energy was proposed, and using

  9. The effect of centrifuging bone cement.

    PubMed

    Davies, J P; Jasty, M; O'Connor, D O; Burke, D W; Harrigan, T P; Harris, W H

    1989-01-01

    We have tested the porosity and fatigue life of five commonly used bone cements: Simplex P, LVC, Zimmer regular, CMW and Palacos R. Tests were conducted with and without centrifugation and with the monomer at room temperature and, except for LVC, at 0 degrees C. We found that the fatigue life of different specimens varied by a factor of nearly 100. It did not depend on porosity alone, but was more influenced by the basic composition of the cement. Simplex P when mixed with monomer at 0 degrees C and centrifuged for 60 seconds had the highest fatigue life and was still sufficiently liquid to use easily. PMID:2915001

  10. Sperm cleanup and centrifugation processing for cryopreservation.

    PubMed

    Sieme, Harald; Oldenhof, Harriëtte

    2015-01-01

    Fertility rates with artificial insemination are highest with good-quality sperm samples. Therefore, nonviable sperm, cellular debris, and seminal plasma are preferably removed from semen samples prior to use or for preservation. Such compounds are sources where reactive oxygen species are generated during storage or upon cryopreservation, impairing sperm function. In this chapter we describe methods to remove seminal plasma and cellular debris from sperm samples, and for selecting morphologically normal motile sperm. The methods that are described here include: ordinary centrifugation, sperm swim-up, glass wool and Sephadex filtration/adherence, and single-layer as well as discontinuous two-layer iodixanol density gradient centrifugation. PMID:25428016

  11. Vacuum chamber-free centrifuge with magnetic bearings

    NASA Astrophysics Data System (ADS)

    Park, Cheol Hoon; Kim, Soohyun; Kim, Kyung-Soo

    2013-09-01

    Centrifuges are devices that separate particles of different densities and sizes through the application of a centrifugal force. If a centrifuge could be operated under atmospheric conditions, all vacuum-related components such as the vacuum chamber, vacuum pump, diffusion pump, and sealing could be removed from a conventional centrifuge system. The design and manufacturing procedure for centrifuges could then be greatly simplified to facilitate the production of lightweight centrifuge systems of smaller volume. Furthermore, the maintenance costs incurred owing to wear and tear due to conventional ball bearings would be eliminated. In this study, we describe a novel vacuum chamber-free centrifuge supported by magnetic bearings. We demonstrate the feasibility of the vacuum chamber-free centrifuge by presenting experimental results that verify its high-speed support capability and motoring power capacity.

  12. Development of a body force model for centrifugal compressors

    E-print Network

    Kottapalli, Anjaney Pramod

    2013-01-01

    This project is focused on modeling the internal ow in centrifugal compressors for the purpose of assessing the onset of rotating stall and surge. The current methods to determine centrifugal compressor stability limits ...

  13. A parametric study of vestibular stimulation during centrifugation

    E-print Network

    Pouly, Jeremie M

    2006-01-01

    Artificial Gravity (AG) provided by short-radius centrifugation is a promising countermeasure to the health problems associated with long duration human spaceflight. Head-turns performed during centrifugation, however, ...

  14. Hydration of gas-phase ytterbium ion complexes studied by experiment and theory

    SciTech Connect

    Rutkowski, Philip X; Michelini, Maria C.; Bray, Travis H.; Russo, Nino; Marcalo, Joaquim; Gibson, John K.

    2011-02-11

    Hydration of ytterbium (III) halide/hydroxide ions produced by electrospray ionization was studied in a quadrupole ion trap mass spectrometer and by density functional theory (DFT). Gas-phase YbX{sub 2}{sup +} and YbX(OH){sup +} (X = OH, Cl, Br, or I) were found to coordinate from one to four water molecules, depending on the ion residence time in the trap. From the time dependence of the hydration steps, relative reaction rates were obtained. It was determined that the second hydration was faster than both the first and third hydrations, and the fourth hydration was the slowest; this ordering reflects a combination of insufficient degrees of freedom for cooling the hot monohydrate ion and decreasing binding energies with increasing hydration number. Hydration energetics and hydrate structures were computed using two approaches of DFT. The relativistic scalar ZORA approach was used with the PBE functional and all-electron TZ2P basis sets; the B3LYP functional was used with the Stuttgart relativistic small-core ANO/ECP basis sets. The parallel experimental and computational results illuminate fundamental aspects of hydration of f-element ion complexes. The experimental observations - kinetics and extent of hydration - are discussed in relationship to the computed structures and energetics of the hydrates. The absence of pentahydrates is in accord with the DFT results, which indicate that the lowest energy structures have the fifth water molecule in the second shell.

  15. LES MOLCULES DANS UN CHAMP CENTRIFUGE INTENSE; par T. SVEDBERG.

    E-print Network

    Paris-Sud XI, Université de

    LES MOLÉCULES DANS UN CHAMP CENTRIFUGE INTENSE; par T. SVEDBERG. Université d'Upsala (Suède). Sommaire. 2014 De l'étude du comportement des molécules dans des champs centrifuges intenses on peut tirer exposée. L'auteur décrit la réalisation des champs centrifuges allant jusqu'à 200 000 fois la pesanteur

  16. THE IMPACT OF UNCERTAIN CENTRIFUGE CAPILLARY PRESSURE ON RESERVOIR SIMULATION

    E-print Network

    Sambridge, Malcolm

    THE IMPACT OF UNCERTAIN CENTRIFUGE CAPILLARY PRESSURE ON RESERVOIR SIMULATION SAM SUBBEY, MIKE estimation of hydrocarbon reserves. The centrifuge procedure provides laboratory data, which can be inverted are uncertain. This paper shows how the uncertainty in centrifuge capillary pressure can be quantified. It also

  17. Drive torque actuation in active surge control of centrifugal compressors

    E-print Network

    Gravdahl, Jan Tommy

    Drive torque actuation in active surge control of centrifugal compressors Jan Tommy Gravdahl , Olav to active surge control is presented for a centrifugal compressor driven by an electrical motor. The main speed Compressor performance control Figure 1: The compression system consists of a centrifugal

  18. Testing of Expansive Clays in a Centrifuge Permeameter

    E-print Network

    Zornberg, Jorge G.

    Testing of Expansive Clays in a Centrifuge Permeameter M. D. Plaisted & J. G. Zornberg with the objective of characterizing the swelling of highly plastic clays using a centrifuge permeameter. The new. This study, conducted using a comparatively simple, non- instrumented centrifuge device complements ongo- ing

  19. Impact recording system to characterise centrifugal S. Villette1

    E-print Network

    Paris-Sud XI, Université de

    1 Impact recording system to characterise centrifugal spreading S. Villette1 ; E. Piron2 ; R of fertiliser centrifugal spreaders. The method consists in recording granule impacts on a cylindrical vertical of fertiliser granules and paves the way to design simple test and diagnostic tools. Keywords Centrifugal

  20. TECHNICAL NOTE Centrifuge cone penetration tests in sand

    E-print Network

    Bolton, Malcolm

    TECHNICAL NOTE Centrifuge cone penetration tests in sand M. D. BOLTON,Ã M. W. GUI,Ã J. GARNIER,{ J. F. CORTE,{ G. BAGGE,{ J. LAUE} and R. RENZIk KEYWORDS: centrifuge modelling; in-situ testing; laboratory tests; piles; sands. INTRODUCTION Centrifuges have been widely adopted in modelling geotechnical

  1. 150 g-ton Capacity Centrifuge Renssealer Polytechnic Institute

    E-print Network

    Salama, Khaled

    NEES@RPI 150 g-ton Capacity Centrifuge Renssealer Polytechnic Institute Department of Civil Institute (NEES@RPI) specializes in geotechnical engineering using the geotechnical centrifuge in 1989, the facility consists of : · A 150 g-ton geotechnical centrifuge · A one and two-dimensional in

  2. COMPARISON OF FATIGUE BEHAVIOR FOR CENTRIFUGALLY CAST AND

    E-print Network

    Beckermann, Christoph

    COMPARISON OF FATIGUE BEHAVIOR FOR CENTRIFUGALLY CAST AND KEEL BLOCK CAST STEEL J.J. Gradman1 , R The objective of this research was to determine if location through the wall thickness of centrifugal castings affects fatigue properties and to compare fatigue and monotonic tensile properties of centrifugal castings

  3. Centrifugal Filter Devices for the Concentration and Purification of

    E-print Network

    Lebendiker, Mario

    Centrifugal Filter Devices for the Concentration and Purification of Biological Samples  Amicon Ultra Ready for an evolution? ® #12;The next stage in centrifugal filter devices. The introduction of Amicon Ultra sets a new standard for centrifugal filter devices. This high performance ultrafiltration

  4. Centrifuge: Integrated Lease Management and Partitioning for Cloud Services

    E-print Network

    Hunt, Galen

    Centrifuge: Integrated Lease Management and Partitioning for Cloud Services Atul Adya , John datacenter lease managers. This paper presents Centrifuge, a datacenter lease manager that solves this problem by integrating parti- tioning and lease management. Centrifuge consists of a set of libraries

  5. Hydraulic design, numerical simulation and BVF diagnosis of high efficiency centrifugal pump

    NASA Astrophysics Data System (ADS)

    Zhang, Y. X.; Chen, L.; Zhou, X.; Jiangand, C. W.; Su, M.

    2012-11-01

    Under the Two-dimensional Flow Theory and the Velocity Coefficient Theory, a centrifugal-pump impeller has been designed, based on the parameters of IS150-125-250 centrifugal pump. And self-compiled programs have been used to complete the hydraulic design of the whole flow passage of centrifugal pump. The space bending and twisting characteristics of the design blade are more obvious. Then, numerical simulation is applied to the inner flow field of the two pumps using RANS (Reynolds Averaged N-S) Equation with a standard k-? two-equation turbulence model. The compare of the numerical simulation data of two centrifugal pumps, getting from 13 working points including design condition, shows that, the design pump has higher head and efficiency in the range of lower flow rate. Based on the numerical results of the inner flow of the design pump and model pump, the boundary vorticity flux (BVF) diagnostics has been used to analyze the BVF distribution of suction surface and pressure surface of two pumps. The result shows that, the BVF distribution of the design pump is more uniform and smooth, with smaller peak value.

  6. Centrifugal governor for internal combustion engines

    Microsoft Academic Search

    Ohnishi

    1986-01-01

    A centrifugal governor is described for use with an internal combustion engine, comprising: a control rack for regulating the quantity of fuel to be supplied to the engine; flyweights radially displaceable in response to the rotational speed of the engine; a tension lever pivotable about a stationary fulcrum in response to the radial displacement of the flyweights; a torque cam

  7. Simulation of Particle Damping under Centrifugal Loads

    Microsoft Academic Search

    Riaz A. Bhatti; Wang Yanrong

    2009-01-01

    Particle damping is a technique to reduce the structural vibrations by means of placing small metallic particles inside a cavity that is attached to the structure at location of high vibration amplitudes. In this paper, we have presented an analytical model to simulate the particle damping of two dimensional transient vibrations in structure operating under high centrifugal loads. The simulation

  8. Centrifugal governor for internal combustion engines

    Microsoft Academic Search

    Ohkoshi

    1987-01-01

    This patent describes a centrifugal governor for use with an internal combustion engine, comprising: a control rack for regulating the quantity of fuel to be supplied to the engine; flyweights radially displaceable in response to the rotational speed of the engine; a tension lever pivotable through an angle dependent upon the amount of radial displacement of the flyweights; a torque

  9. Centrifugal governor for internal combustion engines

    Microsoft Academic Search

    Ohnishi

    1986-01-01

    A centrifugal governor is described for use with an internal combustion engine which consists of: a control rack for regulating the quantity of fuel to be supplied to the engine; flyweights radially displaceable in response to the rotational speed of the engine; a tension lever pivotable through an angle dependent upon the amount of radial displacement of the flyweights; an

  10. Pressure distribution in centrifugal dental casting.

    PubMed

    Nielsen, J P

    1978-02-01

    Equations are developed for liquid metal pressure in centrifugal dental casting, given the instantaneous rotational velocity, density, and certain dimensions of the casting machine and casting pattern. A "reference parabola" is introduced making the fluid pressure concept more understandable. A specially designed specimen demonstrates experimentally the reference parabola at freezing. PMID:355283

  11. Evaluation of an improved centrifugal casting machine.

    PubMed

    Donovan, T E; White, L E

    1985-05-01

    A Type III gold alloy, a silver-palladium alloy, and a base metal alloy were cast in two different centrifugal casting machines. With the number of complete cast mesh squares as an indicator of castability, the Airspin casting machine produced superior castings with all three alloys. The base metal alloy produced the greatest number of complete squares with both casting machines. PMID:3889295

  12. Flow Pattern Characterization for a Centrifugal Impeller

    NASA Astrophysics Data System (ADS)

    Benavides, Efrén M.

    2014-08-01

    This paper proposes a model for characterizing the flow pattern of a centrifugal impeller attending to the severity of the reverse flow. The model assumes 1) a definition of an escaping particle as the one that flows in every operational point from the trailing edge towards the leading edge of the impeller blades, and 2) a characterization of flow where an operational point is said to have a theoretical flow pattern if it is not possible to establish a fully-reversed escaping particle on it. Therefore, the first part of the article is focused on defining an escaping particle for a centrifugal compressor. The model locates over the map of a centrifugal impeller the line that splits the map in two regions: the region on the right hand side, where a theoretical flow pattern can exist, and the region on the left, where a theoretical flow pattern cannot exist. Therefore, the locus of this line marks a frontier where the expected performance of the impeller cannot be sustained as high as expected. The second part of the article uses a high-performance commercial centrifugal impeller wheel for contrasting the model. A qualitative characterization of the surge line, conclusions and discussions are presented.

  13. Differential white cell count by centrifugal microfluidics.

    SciTech Connect

    Sommer, Gregory Jon; Tentori, Augusto M.; Schaff, Ulrich Y.

    2010-07-01

    We present a method for counting white blood cells that is uniquely compatible with centrifugation based microfluidics. Blood is deposited on top of one or more layers of density media within a microfluidic disk. Spinning the disk causes the cell populations within whole blood to settle through the media, reaching an equilibrium based on the density of each cell type. Separation and fluorescence measurement of cell types stained with a DNA dye is demonstrated using this technique. The integrated signal from bands of fluorescent microspheres is shown to be proportional to their initial concentration in suspension. Among the current generation of medical diagnostics are devices based on the principle of centrifuging a CD sized disk functionalized with microfluidics. These portable 'lab on a disk' devices are capable of conducting multiple assays directly from a blood sample, embodied by platforms developed by Gyros, Samsung, and Abaxis. [1,2] However, no centrifugal platform to date includes a differential white blood cell count, which is an important metric complimentary to diagnostic assays. Measuring the differential white blood cell count (the relative fraction of granulocytes, lymphocytes, and monocytes) is a standard medical diagnostic technique useful for identifying sepsis, leukemia, AIDS, radiation exposure, and a host of other conditions that affect the immune system. Several methods exist for measuring the relative white blood cell count including flow cytometry, electrical impedance, and visual identification from a stained drop of blood under a microscope. However, none of these methods is easily incorporated into a centrifugal microfluidic diagnostic platform.

  14. Centrifugal Length Separation of Carbon Nanotubes

    SciTech Connect

    Fagan, Jeffrey A.; Becker, Matthew L.; Chun, Jaehun; Nie, Pingting; Bauer, Barry J.; Simpson, Jeffrey R.; Hight-Walker, Angela; Hobbie, Erik K.

    2008-12-16

    Separation of single-wall carbon nanotubes (SWCNTs) by length via centrifugation in a high density medium, and the characterization of both the separated fractions and the centrifugation process are presented. Significant quantities of the separated SWCNTs ranging in average length from < 50 nm to ?2 ?m were produced, with the distribution width being coupled to the rate of the separation. Less rapid separation is shown to produce narrower distributions; these length fractions, produced using sodium deoxycholate dispersed SWCNTs, were characterized by UV-visible-nearinfrared absorption and fluorescence spectroscopy, dynamic light scattering, Raman scattering, and atomic force microscopy. Several parameters of the separation were additionally explored: SWCNT concentration, added salt concentration, liquid density, rotor speed, surfactant concentration, and the processing temperature. The centrifugation technique is shown to support 10 mg per day scale processing and is applicable to all of the major SWCNT production methods. The cost per unit of the centrifugation-based separation is also demonstrated to be significantly less than size exclusion chromatography-based separations.

  15. Positive feedback stabilization of centrifugal compressor surge

    Microsoft Academic Search

    Frank Willems; W. P. M. H. Heemels; Bram de Jager; Anton A. Stoorvogel

    2002-01-01

    Abstract Stable operation of axial and centrifugal compressors is limited towards low mass 1ows due to the occurrence of surge. The stable operating region can be enlarged by active control. In this study, we use a control valve which is fully closed in the desired operating point and only opens to stabilize the system around this point. As a result,

  16. Nonlinear Sensitive Control of Centrifugal Compressor

    Microsoft Academic Search

    F. Laaouad; M. Bouguerra; A. Hafaifa; A. Iratni

    2007-01-01

    In this work, we treat the problems related to chemical and petrochemical plants of a certain complex process taking the centrifugal compressor as an example, a system being very complex by its physical structure as well as its behaviour (surge phenomenon). We propose to study the application possibilities of the recent control approaches to the compressor behaviour, and consequently evaluate

  17. INTRACELLULAR CENTRIFUGAL SEPARATION OF ORGANELLES IN PHYCOMYCES

    PubMed Central

    Zalokar, Marko

    1969-01-01

    Live sporangiophores of Phycomyces blakesleeanus were centrifuged at 35,000 rpm. The cell contents sedimented into distinct layers, and each layer was studied with an electron microscope and with cytochemical methods. The following layers were found (their volumes and their densities are shown in Fig. 3): 1. polyphosphates; 2. polyphosphates and protein crystals; 3. glycogen; 4. yellow layer with ferritin; 5. ribosomes; 6. protein crystals; 7. mitochondria; 8. mitochondria and fibrils; 9. nuclei; 10. endoplasmic reticulum; 11. vesicles, membranes, and reticulum; 12. vacuole; 13. lipoproteins, membranes; 14. fat droplet. The densities of the various layers were determined by the injection of droplets of inert oils of known density into the sporangiosphores before centrifugation. Sedimented cell organelles could be isolated. Centrifuged nuclei of a lycopene-producing mutant were injected into the intact sporangiophore of an albino host where they induced color formation. The ensuing spores, when plated, gave a mixture of white and colored colonies. It was concluded that cell organelles, sedimented by centrifugation of living sporangiophores, remain alive and can be used for biochemical studies. Microspectrophotometric examination of the layers indicated the presence of cytochromes and flavines in the mitochondria and of cytochromes in the nuclei. No pigments corresponding to the action spectrum for the light growth response were found. PMID:5783870

  18. Centrifuge in space fluid flow visualization experiment

    NASA Technical Reports Server (NTRS)

    Arnold, William A.; Wilcox, William R.; Regel, Liya L.; Dunbar, Bonnie J.

    1993-01-01

    A prototype flow visualization system is constructed to examine buoyancy driven flows during centrifugation in space. An axial density gradient is formed by imposing a thermal gradient between the two ends of the test cell. Numerical computations for this geometry showed that the Prandtl number plays a limited part in determining the flow.

  19. Extracting hydrocarbons from water using a centrifuge

    NASA Astrophysics Data System (ADS)

    Ryabov, A. Yu.; Ilyina, A. A.; Chuikin, A. V.; Velikov, A. A.

    2014-09-01

    An original method for the solid-phase microextraction of hydrocarbons from water using a centrifuge is proposed. Comparative results from the chromatographic elution of substances after liquid-phase and solid-phase microextraction are presented. The percentage of the extraction of substances from aqueous solutions and the minimum detection limit for aromatic and aliphatic compounds are calculated.

  20. Family assessment: Centripetal and centrifugal family systems

    Microsoft Academic Search

    Martha Kelsey-smith; W. Robert Beavers M. D

    1981-01-01

    A consideration of interactional style is useful to both researchers and clinicians interested in family assessment. This paper offers data and process evaluation scales designed to determine family interactional style, conceptualized as a continuum ranging from centripetal (CP) to centrifugal (CF), and containing at the midpoint a mixed area in which facets of both the CP and the CF styles

  1. Centrifugal Pump Experiment for Chemical Engineering Undergraduates

    ERIC Educational Resources Information Center

    Vanderslice, Nicholas; Oberto, Richard; Marrero, Thomas R.

    2012-01-01

    The purpose of this paper is to describe a Centrifugal Pump Experiment that provided an experiential learning experience to chemical engineering undergraduates at the University of Missouri in the spring of 2010 in the Unit Operations Laboratory course. Lab equipment was used by senior students with computer-based data and control technology. In…

  2. Development of a high-specific-speed centrifugal compressor

    SciTech Connect

    Rodgers, C.

    1997-07-01

    This paper describes the development of a subscale single-stage centrifugal compressor with a dimensionless specific speed (Ns) of 1.8, originally designed for full-size application as a high volume flow, low pressure ratio, gas booster compressor. The specific stage is noteworthy in that it provides a benchmark representing the performance potential of very high-specific-speed compressors, of which limited information is found in the open literature. Stage and component test performance characteristics are presented together with traverse results at the impeller exit. Traverse test results were compared with recent CFD computational predictions for an exploratory analytical calibration of a very high-specific-speed impeller geometry. The tested subscale (0.583) compressor essentially satisfied design performance expectations with an overall stage efficiency of 74% including, excessive exit casing losses. It was estimated that stage efficiency could be increased to 81% with exit casing losses halved.

  3. Aerodynamic performance of centrifugal compressors

    SciTech Connect

    Sayyed, S.

    1981-12-01

    Saving money with an efficient pipeline system design depends on accurately predicting compressor performance and ensuring that it meets the manufacturer's guaranteed levels. When shop testing with the actual gas is impractical, an aerodynamic test can ascertain compressor efficiency, but the accuracy and consistency of data acquisition in such tests is critical. Low test-pressure levels necessitate accounting for the effects of Reynolds number and heat transfer. Moreover, the compressor user and manufacturer must agree on the magnitude of the corrections to be applied to the test data.

  4. A systematic study of rare gas atoms encapsulated in small fullerenes using dispersion corrected density functional theory.

    PubMed

    Sure, Rebecca; Tonner, Ralf; Schwerdtfeger, Peter

    2015-01-15

    The most stable fullerene structures from C20 to C60 are chosen to study the energetics and geometrical consequences of encapsulating the rare gas elements He, Ne, or Ar inside the fullerene cage using dispersion corrected density functional theory. An exponential increase in stability is found with increasing number of carbon atoms. A similar exponential law is found for the volume expansion of the cage due to rare gas encapsulation with decreasing number of carbon atoms. We show that dispersion interactions become important with increasing size of the fullerene cage, where Van der Waals forces between the rare gas atom and the fullerene cage start to dominate over repulsive interactions. The smallest fullerenes where encapsulation of a rare gas element is energetically still favorable are He@C48, Ne@C52, and Ar@C58. While dispersion interactions follow the trend Ar?>?Ne?>?He inside C60 due to the trend in the rare gas dipole polarizabilities, repulsive forces become soon dominant with smaller cage size and we have a complete reversal for the energetics of rare gas encapsulation at C50. PMID:25503487

  5. Adsorption of SF6 decomposed gas on anatase (101) and (001) surfaces with oxygen defect: A density functional theory study

    PubMed Central

    Zhang, Xiaoxing; Chen, Qinchuan; Tang, Ju; Hu, Weihua; Zhang, Jinbin

    2014-01-01

    The detection of partial discharge by analyzing the components of SF6 gas in gas-insulated switchgears is important to the diagnosis and assessment of the operational state of power equipment. A gas sensor based on anatase TiO2 is used to detect decomposed gases in SF6. In this paper, first-principle density functional theory calculations are adopted to analyze the adsorption of SO2, SOF2, and SO2F2, the primary decomposition by-products of SF6 under partial discharge, on anatase (101) and (001) surfaces. Simulation results show that the perfect anatase (001) surface has a stronger interaction with the three gases than that of anatase (101), and both surfaces are more sensitive and selective to SO2 than to SOF2 and SO2F2. The selection of a defect surface to SO2, SOF2, and SO2F2 differs from that of a perfect surface. This theoretical result is corroborated by the sensing experiment using a TiO2 nanotube array (TNTA) gas sensor. The calculated values are analyzed to explain the results of the Pt-doped TNTA gas sensor sensing experiment. The results imply that the deposited Pt nanoparticles on the surface increase the active sites of the surface and the gas molecules may decompose upon adsorption on the active sites. PMID:24755845

  6. Gas

    MedlinePLUS

    ... and pain in the belly—especially after a big meal. Foods that can cause gas Some people naturally produce ... your stomach or throw up . Your breasts are big and sore . The area around your nipples gets darker. You crave certain foods. Or you really dislike certain foods. You feel ...

  7. Stresa, Italy, 26-28 April 2006 A SILICON-BASED MICRO GAS TURBINE ENGINE FOR POWER GENERATION

    E-print Network

    Paris-Sud XI, Université de

    gas turbine engine consists of a micro combustor, a turbine and a centrifugal compressor and turbine consist of centrifugal blades with two-dimensional profiles. Centrifugal Compressor Combustor. Comprehensive simulation has been implemented to optimal the component design. We have successfully demonstrated

  8. Mechanisms of Sensorimotor Adaptation to Centrifugation

    NASA Technical Reports Server (NTRS)

    Paloski, W. H.; Wood, S. J.; Kaufman, G. D.

    1999-01-01

    We postulate that centripetal acceleration induced by centrifugation can be used as an inflight sensorimotor countermeasure to retain and/or promote appropriate crewmember responses to sustained changes in gravito-inertial force conditions. Active voluntary motion is required to promote vestibular system conditioning, and both visual and graviceptor sensory feedback are critical for evaluating internal representations of spatial orientation. The goal of our investigation is to use centrifugation to develop an analog to the conflicting visual/gravito-inertial force environment experienced during space flight, and to use voluntary head movements during centrifugation to study mechanisms of adaptation to altered gravity environments. We address the following two hypotheses: (1) Discordant canal-otolith feedback during head movements in a hypergravity tilted environment will cause a reorganization of the spatial processing required for multisensory integration and motor control, resulting in decreased postural stability upon return to normal gravity environment. (2) Adaptation to this "gravito-inertial tilt distortion" will result in a negative after-effect, and readaptation will be expressed by return of postural stability to baseline conditions. During the third year of our grant we concentrated on examining changes in balance control following 90-180 min of centrifugation at 1.4 9. We also began a control study in which we exposed subjects to 90 min of sustained roll tilt in a static (non-rotating) chair. This allowed us to examine adaptation to roll tilt without the hypergravity induced by centrifugation. To these ends, we addressed the question: Is gravity an internal calibration reference for postural control? The remainder of this report is limited to presenting preliminary findings from this study.

  9. Effects of vaned diffuser pressure recovery on centrifugal compressor stage performance

    E-print Network

    Eason, Robyn Monique

    1985-01-01

    of vened diffuser static pressure recovery on centrifugal ccxn- pressor stage performance are presented. A single-stage radial canpres- sor experiencing actual operating conditions in a Ford regenerative gas turbine engine was utilized... in the experixental investigation. different vaned diffusers were tested (with the same impeller). The analytical investigation consisted of employing Herbert's semi empirical prediction code. Results indicate a weak correlation exists between diffuser static...

  10. Density functional theory of a trapped Bose gas with tunable scattering length: From weak-coupling to unitarity

    NASA Astrophysics Data System (ADS)

    Rossi, M.; Ancilotto, F.; Salasnich, L.; Toigo, F.

    2015-04-01

    We study an interacting Bose gas at T = 0 under isotropic harmonic confinement within Density Functional Theory in the Local Density approximation. The energy density functional, which spans the whole range of positive scattering lengths up to the unitary regime (infinite scattering length), is obtained by fitting the recently calculated Monte Carlo bulk equation of state [Phys. Rev. A 89, 041602(R) (2014)]. We compare the density profiles of the trapped gas with those obtained by MC calculations. We solve the time-dependent Density Functional equation to study the effect of increasing values of the interaction strength on the frequencies of monopole and quadrupole oscillations of the trapped gas. We find that the monopole breathing mode shows a non-monotonous behavior as a function of the scattering length. We also consider the damping effect of three-body losses on such modes.

  11. Quasiclassical Theory of Shubnikov-de Haas Effect in 2D Electron Gas

    NASA Astrophysics Data System (ADS)

    Laikhtman, B.; Altshuler, E. L.

    1994-06-01

    A new approach to the theory of magneto-transport in 2D gas is developed. We make use of Keldysh technique and introduce a modified Green?s function which is translationally invariant and gauge invariant. The modification simplifies the calculation of diagrams and allows us to obtain a new helpful addition theorem for the electron wave functions in magnetic field. The modified Green?s function is very convenient to follow the transition between quantum magnetic transport and transport in zero magnetic field. For the calculation of conductivity we use the self-consistent Born approximation (SCBA). We carefully check its validity and figure out the physical meaning of the corresponding conditions. All specific calculations are made for the case when the separation between Landau levels, ??, is much smaller than the Fermi energy, without limiting the magnitude of ?? relative to the width of the levels (induced by scattering), ?. For the first time the case of a long-range scattering potential is carefully studied. We study magneto-oscillation effects with the help of an evolution equation for the Green?s function. In this equation two relaxation times, the single particle relaxation time and the transport relaxation time, naturally come about. Analytical results for the conductivity tensor are obtained for both the Shubnikov-de Haas effect, when ?? ? ?, and the quantum Hall regime, ?? ? ?. In the latter the temperature dependence of the conductivity depends on the relation between the temperature, ??, and ?. Although SCBA does not describe localization, it, however, allows one to separate the Shubnikov-de Haas effect from the quantum Hall effect.

  12. Partition functions of superconformal Chern-Simons theories from Fermi gas approach

    NASA Astrophysics Data System (ADS)

    Moriyama, Sanefumi; Nosaka, Tomoki

    2014-11-01

    We study the partition function of three-dimensional superconformal Chern-Simons theories of the circular quiver type, which are natural generalizations of the ABJM theory, the worldvolume theory of M2-branes. In the ABJM case, it was known that the perturbative part of the partition function sums up to the Airy function as Z( N) = e A C -1/3Ai[ C -1/3( N - B)] with coefficients C, B and A and that for the non-perturbative part the divergences coming from the coefficients of worldsheet instantons and membrane instantons cancel among themselves. We find that many of the interesting properties in the ABJM theory are extended to the general superconformal Chern-Simons theories. Especially, we find an explicit expression of B for general theories, a conjectural form of A for a special class of theories, and cancellation in the non-perturbative coefficients for the simplest theory next to the ABJM theory.

  13. Visible excimer bands of the K-noble-gas and Na-noble-gas molecules: Comparison of experiment with theory

    Microsoft Academic Search

    A. C. Tam; T. Yabuzaki; S. M. Curry; W. Happer

    1978-01-01

    The visible emission bands from K(5S)Xe, K(5S)Kr, Na(4S)Xe, and Na(4S)Kr excimers have been observed experimentally, the potassium excimers being produced by a violet Kr+ laser excitation and the sodium excimers by a discharge. These observed profiles are compared with calculated profiles based on Gallagher's quasistatic theory and Pascale's molecular potentials and oscillator strengths. Qualitative conclusions are drawn concerning the shapes

  14. Axial inlet conversion to a centrifugal compressor with magnetic bearings

    SciTech Connect

    Novecosky, T. (NOVA Corp., Edmonton, Alberta (Canada))

    1994-01-01

    NOVA's Alberta Gas Transmission Division transports natural gas via pipeline throughout the province of Alberta, Canada, exporting it to eastern Canada, US, and British Columbia. There is a continuing effort to operate the facilities and pipeline at the highest possible efficiency. One area being addressed to improve efficiency is compression of the gas. By improving compressor efficiency, fuel consumption and hence operating costs can be reduced. One method of improving compressor efficiency is by converting the compressor to an axial inlet configuration, a conversion that has been carried out more frequently in the past years. Concurrently, conventional hydrodynamic bearings have been replaced with magnetic bearings on many centrifugal compressors. This paper discusses the design and installation for converting a radial overhung unit to an axial inlet configuration, having both magnetic bearings and a thrust reducer. The thrust reducer is required to reduce axial compressor shaft loads, to a level that allows the practical installation of magnetic bearings within the space limitations of the compressor (Bear and Gibson, 1992).

  15. The influence of quantum field fluctuations on chaotic dynamics of Yang-Mills system II. The role of the centrifugal term

    E-print Network

    V. I. Kuvshinov; A. V. Kuzmin; V. A. Piatrou

    2005-11-27

    We have considered SU(2)xU(1) gauge field theory describing electroweak interactions. We have demonstrated that centrifugal term in model Hamiltonian increases the region of regular dynamics of Yang-Mills and Higgs fields system at low densities of energy. Also we have found analytically the approximate relation for critical density of energy of the order to chaos transition on centrifugal constant. It is necessary to note that mentioned increase of the region of regular dynamics has linear dependance on the value of the centrifugal constant.

  16. A mechanics approach for wet gas flow metering, theory and application to flow loop tests

    Microsoft Academic Search

    Cadalen Sébastien; Lance Michel

    2011-01-01

    New technology combined to the rise of the barrel price make wet gas flow metering of primary importance. A Venturi and a multienergy gamma ray hold-up meter provide capital information to estimate gas and liquid flow rates with the required metering accuracy. Starting from Navier–Stokes’ equations, the two-phase flow is modeled with a three 1D equations system for gas, liquid

  17. Miniature Gas-Circulating Machine

    NASA Technical Reports Server (NTRS)

    Swift, Walter L.; Valenzuela, Javier A.; Sixsmith, Herbert; Nutt, William E.

    1993-01-01

    Proposed gas-circulating machine consists essentially of centrifugal pump driven by induction motor. Noncontact bearings suppress wear and contamination. Used to circulate helium (or possibly hydrogen or another gas) in regeneration sorption-compressor refrigeration system aboard spacecraft. Also proves useful in terrestrial applications in which long life, reliability, and low contamination essential.

  18. Spaceborne centrifugal relays for spacecraft propulsion

    NASA Technical Reports Server (NTRS)

    Ouzidane, Malika

    1991-01-01

    Acceleration using centrifugal relays is a recently discovered method for the acceleration of spaceborne payloads to high velocity at high thrust. Centrifugal relays are moving rotors which progressively accelerate reaction mass to higher velocities. One important engineering problem consists of accurately tracking the position of the projectiles and rotors and guiding each projectile exactly onto the appropriate guide tracks on each rotor. The topics of this research are the system kinematics and dynamics and the computerized guidance system which will allow the projectile to approach each rotor with exact timing with respect to the rotor rotation period and with very small errors in lateral positions. Kinematics studies include analysis of rotor and projectile positions versus time and projectile/rotor interactions. Guidance studies include a detailed description of the tracking mechanism (interrupt of optical beams) and the aiming mechanism (electromagnetic focusing) including the design of electromagnetic deflection coils and the switching circuitry.

  19. Optimum design for LRE centrifugal pumps

    NASA Astrophysics Data System (ADS)

    Zhu, Zuchao; Zhang, Guoqian; Sun, Jiren

    1995-05-01

    We set up a mathematical model to predict low specific speed liquid rocket engine (LRE) centrifugal pump unit performance. Using the model in question, performance predictions were carried out for 10 types of LRE centrifugal pumps. Relative errors between experimental values and predicted values associated with efficiency and lift were all within 4%. Using the model in question, design optimization with efficiency as the target function was carried out on AM-7H and O pumps as well as AM-1R pumps and AM-50 pumps. Results clearly show that, with a presupposition of surety systems possessing high vapor corrosion characteristics, the efficiencies of these four types of pumps can be respectively raised 6.5%, 5.22%, 5.2%, and 4.41%.

  20. High stability design for new centrifugal compressor

    NASA Technical Reports Server (NTRS)

    Kanki, H.; Katayama, K.; Morii, S.; Mouri, Y.; Umemura, S.; Ozawa, U.; Oda, T.

    1989-01-01

    It is essential that high-performance centrifugal compressors be free of subsynchronous vibrations. A new high-performance centrifugal compressor has been developed by applying the latest rotordynamics knowledge and design techniques: (1) To improve the system damping, a specially designed oil film seal was developed. This seal attained a damping ratio three times that of the conventional design. The oil film seal contains a special damper ring in the seal cartridge. (2) To reduce the destabilizing effect of the labyrinth seal, a special swirl canceler (anti-swirl nozzle) was applied to the balance piston seal. (3) To confirm the system damping margin, the dynamic simulation rotor model test and the full load test applied the vibration exciting test in actual load conditions.

  1. Hydraulic design and performance analysis of low specific speed centrifugal pump

    NASA Astrophysics Data System (ADS)

    Zhou, X.; Zhang, Y. X.; Ji, Z. L.; Chen, L.

    2012-11-01

    Since low specific speed centrifugal pump with long narrow flow divergent channels has positive slope of head-capacity characteristic curve, low flow rate instability and high flow rate power overload, special events about its hydraulic design are still under study. This paper demonstrates a method for hydraulic design of low specific speed centrifugal pump complex impeller (with splitter blades) which is based on 2D flow theory. In this method, obtain the basic geometry parameters by empirical correlation, adjust impeller profile according to given flow cross section area distribution and wrapping angles distribution, relate the position of splitter blades to slip factor. Based on this method, low specific speed centrifugal pump impellers have been designed using the same design parameters (Head, Capacity, Rotation Speed, etc) with different factors. And 3D turbulent flow fields in design pumps have been solved by using RANS equations with RNG k-epsilon turbulence model. The investigation to the effects of different splitter blades on velocity distributions and pressure distributions along the flow channels and hydraulic performance of centrifugal pumps are presented. The result shows that properly placed splitter blades by choosing suitable design factors will improve the flow in the pump and enhance the hydraulic performance of it.

  2. Centrifugal and gravity driven convection in rotating porous media -- An analogy with the inclined porous layer

    SciTech Connect

    Govender, S.; Vadasz, P. [Univ. of Durban-Westville, Durban (South Africa). Dept. of Mechanical Engineering

    1995-12-31

    An analogy is shown to exist between free convection in a rotating porous layer subject to both gravity and centrifugal forces, and natural convection in an inclined porous layer subject only to gravity. An analytical three-dimensional solution to the convection problem in a vertical porous layer located far away from the center of rotation and subject to gravitational and centrifugal forces is presented. Resolving the gravity related Rayleigh number for the inclined porous layer into horizontal and vertical components and considering the rotating porous layer in a vertical orientation, the analogy between the two cases is derived. A transition point beyond which no real solutions exist for the critical value of the centrifugal Rayleigh number was evaluated. This transition is shown to be similar to the transition found for the angle of inclination in the inclined porous layer. The marginal stability criterion is established in terms of the critical centrifugal Rayleigh number and a critical wave number. The linear stability theory is used to establish the conditions necessary for different types of convection patterns to exist, while a three-dimensional spectral method is used to predict theoretically the convective flow structure. A heat pipe is used for illustration.

  3. Windmilling characteristics of centrifugal-flow turbojets

    Microsoft Academic Search

    Yoo Il Su; Song Seung Jin; Lim Jin Shik

    2004-01-01

    A new nondimensional method for predicting the windmilling performance of centrifugal flow turbojet engines in flight has\\u000a been developed. The method incorporates loss correlations to estimate the performance of major engine components. Given basic\\u000a engine geometry, flight Mach number, and ambient conditions, this method predicts transient and steady-state windmilling performance.\\u000a Thus, this method can be used during the preliminary design

  4. Operating and maintenance guidelines for screenbowl centrifuges

    SciTech Connect

    Jahnig, W.S.R.; Bratton, R.; Luttrell, G. [Decanter Machine, Johnson City, TN (United States)

    2009-01-15

    Plant dewatering circuits equipped with screenbowl centrifuges need to be well designed, properly operated, and adequately maintained to maximize the dewatering performance. The most important 'feed variables' are particle size, dry solids feed rate and slurry flow rate. The most important 'machine variables' include pool depth, rotational speed and gearbox ratio. The article discusses the effect of these parameters and offers some maintenance guidelines. The article was adapted from a paper presented at CoalPrep 2008. 6 refs., 2 figs., 2 tabs.

  5. CENTRIFUGAL VIBRATION TEST OF RC PILE FOUNDATION

    NASA Astrophysics Data System (ADS)

    Higuchi, Shunichi; Tsutsumiuchi, Takahiro; Otsuka, Rinna; Ito, Koji; Ejiri, Joji

    It is necessary that nonlinear responses of structures are clarified by soil-structure interaction analysis for the purpose of evaluating the seismic performances of underground structure or foundation structure. In this research, centrifuge shake table tests of reinforced concrete pile foundation installed in the liquefied ground were conducted. Then, finite element analyses for the tests were conducted to confirm an applicability of the analytical method by comparing the experimental results and analytical results.

  6. Centrifugal shot blasting. Innovative technology summary report

    SciTech Connect

    Not Available

    1999-07-01

    At the US Department of Energy (DOE) Fernald Environmental Management Project (FEMP), the Facilities Closure and Demolition Projects Integrated Remedial Design/Remedial Action (RD/RA) work plan calls for the removal of one inch (1 in) depth of concrete surface in areas where contamination with technetium-99 has been identified. This report describes a comparative demonstration between two concrete removal technologies: an innovative system using Centrifugal Shot Blasting (CSB) and a modified baseline technology called a rotary drum planer.

  7. Free of centrifugal acceleration spacetime - Geodesics

    E-print Network

    Hristu Culetu

    2013-04-27

    A static spacetime with no centrifugal repulsion, previously studied by Dadhich, is investigate in this paper. The source of curvature is considered to be an anisotropic fluid with $\\rho = -p_{r}$ and constant angular pressures. The positive parameter from the line-element is interpreted as the invariant acceleration of a static observer. We found that the Tolman-Komar gravitational energy is finite everywhere. The timelike and null geodesics of the spacetime are examined.

  8. Wave-driven Countercurrent Plasma Centrifuge

    SciTech Connect

    A.J. Fetterman and N.J. Fisch

    2009-03-20

    A method for driving rotation and a countercurrent flow in a fully ionized plasma centrifuge is described. The rotation is produced by radiofrequency waves near the cyclotron resonance. The wave energy is transferred into potential energy in a manner similar to the ? channeling effect. The countercurrent flow may also be driven by radiofrequency waves. By driving both the rotation and the flow pattern using waves instead of electrodes, physical and engineering issues may be avoided.

  9. Ni(NiO)/single-walled carbon nanotubes composite: Synthesis of electro-deposition, gas sensing property for NO gas and density functional theory calculation

    SciTech Connect

    Li, Li; Zhang, Guo; Chen, Lei [Key Laboratory of Chemical Engineering Process and Technology for High-efficiency Conversion, College of Heilongjiang Province, Heilongjiang University, Harbin 150080 (China)] [Key Laboratory of Chemical Engineering Process and Technology for High-efficiency Conversion, College of Heilongjiang Province, Heilongjiang University, Harbin 150080 (China); Bi, Hong-Mei [Key Laboratory of Functional Inorganic Material Chemistry, Ministry of Education, School of Chemistry and Materials Science, Heilongjiang University, Harbin 150080 (China)] [Key Laboratory of Functional Inorganic Material Chemistry, Ministry of Education, School of Chemistry and Materials Science, Heilongjiang University, Harbin 150080 (China); Shi, Ke-Ying, E-mail: shikeying2008@yahoo.cn [Key Laboratory of Functional Inorganic Material Chemistry, Ministry of Education, School of Chemistry and Materials Science, Heilongjiang University, Harbin 150080 (China)] [Key Laboratory of Functional Inorganic Material Chemistry, Ministry of Education, School of Chemistry and Materials Science, Heilongjiang University, Harbin 150080 (China)

    2013-02-15

    Graphical abstract: The Ni(NiO)/semiconducting single-walled carbon nanotubes composite collected from the cathode after electro-deposition shows a high sensitivity to low-concentration NO gas at room temperature (18 °C). Display Omitted Highlights: ? Ni(NiO) nanoparticles were deposited on semiconducting SWCNTs by electro-deposition. ? Ni(NiO)/semiconducting SWCNTs film shows a high sensitivity to NO gas at 18 °C. ?Theoretical calculation reveals electron transfer from SWCNTs to NO via Ni. -- Abstract: Single-walled carbon nanotubes which contains metallic SWCNTs (m-SWCNTs) and semiconducting SWCNTs (s-SWCNTs) have been obtained under electric arc discharge. Their separation can be effectively achieved by the electro-deposition method. The Ni(NiO)/s-SWCNTs composite was found on cathode where Ni was partially oxidized to NiO at ambient condition with Ni(NiO) nanoparticles deposited uniformly on the bundles of SWCNTs. These results were confirmed by Raman spectra, transmission electron microscopy (TEM), scanning electron microscopy (SEM), UV–vis–NIR and TG characterizations. Furthermore, investigation of the gas sensing property of Ni(NiO)/s-SWCNTs composite film to NO gas at 18 °C demonstrated the sensitivity was approximately 5% at the concentration of 97 ppb. Moreover, density functional theory (DFT) calculations were performed to explore the sensing mechanism which suggested the adsorption of NO molecules onto the composite through N–Ni interaction as well as the proposition of electron transfer mechanisms from SWCNTs to NO via the Ni medium.

  10. Behavior of capillary valves in centrifugal microfluidic devices prepared by three-dimensional printing

    Microsoft Academic Search

    Jessica L. Moore; Austin McCuiston; Isaac Mittendorf; Rudy Ottway; R. Daniel Johnson

    2011-01-01

    This paper details the behavior of capillary valves in centrifugal microfluidic devices prepared by three-dimensional (3D),\\u000a or solid-object, printing. Microfluidic structures containing valve channels with different widths, heights, and radial distances\\u000a from the center of rotation were studied and compared with extant capillary valve theories. Due to the printing process, the\\u000a produced valve channels possessed a ridged or “scalloped” pattern.

  11. Ion Fractionation at the Surface of Aqueous Inorganic Salt Solutions by Means of a `Film Centrifuge'

    Microsoft Academic Search

    P. H. Koske; H. Martin

    1972-01-01

    The predictions of Gibbs's lawnd the electrolyte theory about the (negative) adsorption of salts on the surface of aqueous salt solutions are compared with the results of an analysis of very thin surface films skimmed by means of a 'film centrifuge' from a solution containing two different salts. The separation effects observed on the salt mixtures CsC1\\/NaC1, BaCl\\/ NaC1, BaCl\\/CsC1,

  12. Confinement of Plasma along Shaped Open Magnetic Fields from the Centrifugal Force of Supersonic Plasma Rotation

    SciTech Connect

    Teodorescu, C.; Young, W. C.; Swan, G. W. S.; Ellis, R. F.; Hassam, A. B.; Romero-Talamas, C. A. [University of Maryland, College Park, Maryland 20742 (United States)

    2010-08-20

    Interferometric density measurements in plasmas rotating in shaped, open magnetic fields demonstrate strong confinement of plasma parallel to the magnetic field, with density drops of more than a factor of 10. Taken together with spectroscopic measurements of supersonic ExB rotation of sonic Mach 2, these measurements are in agreement with ideal MHD theory which predicts large parallel pressure drops balanced by centrifugal forces in supersonically rotating plasmas.

  13. Shallow water model for horizontal centrifugal casting

    NASA Astrophysics Data System (ADS)

    Bohá?ek, J.; Kharicha, A.; Ludwig, A.; Wu, M.

    2012-07-01

    A numerical model was proposed to simulate the solidification process of an outer shell of work roll made by the horizontal centrifugal casting technique. Shallow water model was adopted to solve the 2D average flow dynamics of melt spreading and the average temperature distribution inside the centrifugal casting mould by considering the centrifugal force, Coriolis force, viscous force due to zero velocity on the mould wall, gravity, and energy transport by the flow. Additionally, a 1D sub-model was implemented to consider the heat transfer in the radial direction from the solidifying shell to the mould. The solidification front was tracked by fulfilling the Stefan condition. Radiative and convective heat losses were included from both, the free liquid surface and the outer wall of the mould. Several cases were simulated with the following assumed initial conditions: constant height of the liquid metal (10, 20, and 30 mm), uniform temperature of the free liquid surface (1755 K). The simulation results have shown that while the solidification front remained rather flat, the free surface was disturbed by waves. The amplitude of waves increased with the liquid height. Free surface waves diminished as the solidification proceeded.

  14. Femoral development in chronically centrifuged rats

    NASA Technical Reports Server (NTRS)

    Smith, S. D.

    1977-01-01

    Groups of 30-d-old male and female rats were centrifuged at 2.00 G (RE, Rotation Experimental), 1.05 G (RC, Rotation Control) or exposed to the noise and wind of the centrifuge at 1.00 G (EC, Earth Control) for periods of 1, 2, 4, 8, and 16 weeks. Measurements of their femurs indicated that exposure to centrifugation a) decreased femoral length in RE animals, b) increased femoral length in RC animals, c) reduced femoral diameter in RE and RC animals, d) increased L/D ratios in RC animals, e) decreased L/D ratios in RE animals, f) increased femur length/body weight in RE animals, g) decreased cortical thickness (CT) in RE animals, h) increased relative CT in RE animals, and decreased it in RC animals, i) accelerated ossification in RC femoral heads, j) thinned and distorted RE epiphyseal plates, and k) thickened condylar cartilage in RE females. The effects tended to be strongly sexually dimorphic, with females more severely affected by the stress than males.

  15. Stable isotope enrichment using a plasma centrifuge

    NASA Astrophysics Data System (ADS)

    Krishnan, Mahadevan; Bures, Brian; Madden, Robert

    2012-10-01

    A primary goal of the Department of Energy's Isotope Development and Production for Research and Applications Program (Isotope Program) within the Office of Nuclear Physics (NP) is to produce isotopes that are in short supply in the U.S. and of which there exists no or insufficient domestic commercial production capability. A vacuum arc plasma centrifuge is a rigid rotor column of metal plasma in which centrifugal forces re-distribute ions radially according to their mass/charge ratio. Early work demonstrated rotation at 2 million rpm and separation of various stable isotopes. The spinning plasma column had a Gaussian flux profile, peaked on the rigid rotor axis. This work adopts a more efficient approach, with the plasma created as a hollow column, wherein the flux is concentrated at larger radii where the centrifugal action is highest. By tailoring the vacuum arc discharge geometry, the rotation rate can also be increased to ˜10 million rpm. Data from Cu, Al and other metal plasmas will be presented and discussed in light of enriched stable isotopes needed for research and medicine.

  16. The Application of Centrifuges 'Reduced Gravity' Research.

    NASA Astrophysics Data System (ADS)

    van Loon, Jack J. W. A.

    It is shown that life has emerged on Earth somewhere in the early Archaean (3800-2500 million years ago). Since then life has evolved from single cell into to multicellular complex organism under unit gravity conditions. Little is known about how life would have been evolved under different gravity conditions. In light of the current quests for Earth-like planets by astronomers; what life forms could be expected on planets with different gravity fields? Also the human endeavors in spaceflight (microgravity) and exploration programs (Moon, Mars) it is interesting and might be even vital to know and understand how gravity acts upon the human body in long duration space flights. Hyper-gravity, any acceleration acceding 9.81 ms-2, can relatively easily be generated on Earth using centrifuges. Long duration hypo-gravity (¡9.81 ms-2) is more cumbersome. For real microgravity we need free falling satellites such as ISS. For simulation on ground one can use clinostats, random positioning machines or levitating magnets. But could centrifuges also be applied to study a reduced gravity environment? What I would explore in this paper are the possibilities how centrifuges could be applied to study the effects of a 'reduced gravity environment' in, especially, life sciences studies.

  17. Research opportunities with the Centrifuge Facility

    NASA Technical Reports Server (NTRS)

    Funk, Glenn A.

    1992-01-01

    The Centrifuge Facility on Space Station Freedom will consist of a 2.5-meter diameter Centrifuge accommodating two concentric rings of habitats and providing variable g-forces between 0.01 g and 2.0 g; modular habitats providing housing and lifesupport for rats, mice, and plants; a habitat holding system providing power, water, airflow and other utilities to several modular habitats; and a life sciences glovebox, an isolated work volume accommodating simultaneous operations by at least two scientists and providing lighting, airflow, video and data access, and other experiment support functions. The centrifuge facility will enable long-duration animal and plant microgravity research not previously possible in the NASA flight research program. It will offer unprecedented opportunities for use of on-board 1-g control populations and statistically significant numbers of specimens. On orbit 1-g controls will allow separation of the effects of microgravity from other environmental factors. Its selectable-g and simultaneous multiple-g capabilities will enable studies of gravitational thresholds, the use of artificial gravity as a countermeasure to the effects of microgravity, and ready simulation of Lunar and Martian gravities.

  18. Excessive centrifugal fields damage high density lipoprotein.

    PubMed

    Munroe, William H; Phillips, Martin L; Schumaker, Verne N

    2015-06-01

    HDL is typically isolated ultracentrifugally at 40,000 rpm or greater, however, such high centrifugal forces are responsible for altering the recovered HDL particle. We demonstrate that this damage to HDL begins at approximately 30,000 rpm and the magnitude of loss increases in a rotor speed-dependent manner. The HDL is affected by elevated ultracentrifugal fields resulting in a lower particle density due to the shedding of associated proteins. To circumvent the alteration of the recovered HDL, we utilize a KBr-containing density gradient and a lowered rotor speed of 15,000 rpm to separate the lipoproteins using a single 96 h centrifugation step. This recovers the HDL at two density ranges; the bulk of the material has a density of about 1.115 g/ml, while lessor amounts of material are recovered at >1.2 g/ml. Thus, demonstrating the isolation of intact HDL is possible utilizing lower centrifuge rotor speeds. PMID:25910941

  19. In-vivo Centrifugation of Drosophila Embryos

    PubMed Central

    Tran, Susan L.; Welte, Michael A.

    2010-01-01

    A major strategy for purifying and isolating different types of intracellular organelles is to separate them from each other based on differences in buoyant density. However, when cells are disrupted prior to centrifugation, proteins and organelles in this non-native environment often inappropriately stick to each other. Here we describe a method to separate organelles by density in intact, living Drosophila embryos. Early embryos before cellularization are harvested from population cages, and their outer egg shells are removed by treatment with 50% bleach. Embryos are then transferred to a small agar plate and inserted, posterior end first, into small vertical holes in the agar. The plates containing embedded embryos are centrifuged for 30 min at 3000g. The agar supports the embryos and keeps them in a defined orientation. Afterwards, the embryos are dug out of the agar with a blunt needle. Centrifugation separates major organelles into distinct layers, a stratification easily visible by bright-field microscopy. A number of fluorescent markers are available to confirm successful stratification in living embryos. Proteins associated with certain organelles will be enriched in a particular layer, demonstrating colocalization. Individual layers can be recovered for biochemical analysis or transplantation into donor eggs. This technique is applicable for organelle separation in other large cells, including the eggs and oocytes of diverse species. PMID:20613707

  20. Hydrodynamic modeling of dense gas-fluidised beds using the kinetic theory of granular flow: effect of coefficient of restitution on bed dynamics

    Microsoft Academic Search

    M. J. V. Goldschmidt; J. A. M. Kuipers; Swaaij van W. P. M

    2000-01-01

    A two-dimensional multi-fluid Eulerian CFD model with closure laws according to the kinetic theory of granular flow has been applied to study the influence of the coefficient of restitution on the hydrodynamics of dense gas-fluidised beds. It is demonstrated that hydrodynamics of dense gas-fluidised beds (i.e. gas bubbles behaviour) strongly depend on the amount of energy dissipated in particle-particle encounters.

  1. Hydrodynamic modelling of dense gas-fluidised beds using the kinetic theory of granular flow: effect of coefficient of restitution on bed dynamics

    Microsoft Academic Search

    M. J. V. Goldschmidt; J. A. M. Kuipers; W. P. M. van Swaaij

    2001-01-01

    A two-dimensional multi-fluid Eulerian CFD model with closure laws according to the kinetic theory of granular flow has been applied to study the influence of the coefficient of restitution on the hydrodynamics of dense gas-fluidised beds. It is demonstrated that hydrodynamics of dense gas-fluidised beds (i.e. gas bubbles behaviour) strongly depend on the amount of energy dissipated in particle–particle encounters.

  2. Characterization of centrifugally-loaded flame migration for ultra-compact combustors

    NASA Astrophysics Data System (ADS)

    LeBay, Kenneth D.

    The Air Force Research Laboratory (AFRL) has designed a centrifugally-loaded Ultra-Compact Combustor (UCC) showing viable merit for reducing gas turbine combustor length by as much as 66%. The overarching goal of this research was to characterize the migration of centrifugally-loaded flames in a sectional model of the UCC to enable scaling of the design from 15 cm to the 50--75 cm diameter of most engines. Two-line Planar Laser-Induced Fluorescence thermometry (PLIF) of OH, time-resolved Particle Image Velocimetry (PIV), and high-speed video data were collected. Using a sectional UCC model, the flame migration angle was determined to be a function of the UCC/core velocity ratio (VR) while both the VR and the centrifugal or "g-load" affected the migration quantity. Higher g-loads and lower VRs yielding higher migration but lower VRs had lower core flow temperatures due to higher core air mass flow. A comparison of the straight and curved UCC sections showed the centrifugal load increased the flame migration but increased unsteadiness. The flame migration into the core was estimated using pressure and temperature measurements upstream, and PIV measurements downstream of the core flow interface with constant density and velocity profile assumptions. The flame migration quantity was used to estimate the core flow temperature which was in relatively good agreement with the measured PLIF values. The migration quantity scaled relatively linearly with the UCC tangential velocity, which corresponds to the g-load value, with the slope determined by the VR. A simple analytical model resulted for the dependence of the migration quantity on the tangential velocity and VR. The quantitative relationships determined in this research provided a detailed description of the migration of centrifugally-loaded flames in a sectional UCC.

  3. Erosion in radial inflow turbines. Volume 2: Balance of centrifugal and radial drag forces on erosive particles

    NASA Technical Reports Server (NTRS)

    Clevenger, W. B., Jr.; Tabakoff, W.

    1974-01-01

    The particle motion in two-dimensional free and forced inward flowing vortices is considered. A particle in such a flow field experiences a balance between the aerodynamic drag forces that tend to drive erosive particles toward the axis, and centrifugal forces that prevent these particles from traveling toward the axis. Results predict that certain sizes of particles will achieve a stable orbit about the turbine axis in the inward flowing free vortex. In this condition, the radial drag force is equal to the centrifugal force. The sizes of particles that will achieve a stable orbit is shown to be related to the gas flow velocity diagram at a particular radius. A second analysis yields a description of particle sizes that will experience a centrifugal force that is greater than the radial component of the aerodynamic drag force for a more general type of particle motion.

  4. Numerical analysis of flow in ultra micro centrifugal compressor -influence of meridional configuration

    NASA Astrophysics Data System (ADS)

    Kaneko, Masanao; Tsujita, Hoshio; Hirano, Toshiyuki

    2013-04-01

    A single stage ultra micro centrifugal compressor constituting ultra micro gas turbine is required to operate at high rotational speed in order to achieve the pressure ratio which establishes the gas turbine cycle. As a consequence, the aerodynamic losses can be increased by the interaction of a shock wave with the boundary layer on the blade surface. Moreover, the centrifugal force which exceeds the allowable stress of the impeller material can act on the root of blades. On the other hand, the restrictions of processing technology for the downsizing of impeller not only relatively enlarge the size of tip clearance but also make it difficult to shape the impeller with the three-dimensional blade. Therefore, it is important to establish the design technology for the impeller with the two-dimensional blade which possesses the sufficient aerodynamic performance and enough strength to bear the centrifugal force caused by the high rotational speed. In this study, the flow in two types of impeller with the two-dimensional blade which have different meridional configuration was analyzed numerically. The computed results clarified the influence of the meridional configuration on the loss generations in the impeller passage.

  5. Application of convolution theory for solving non-linear flow problems: gas flow systems 

    E-print Network

    Mireles, Thomas Joseph

    1995-01-01

    of the gas differential equation. This solution is "semi-analytical" because although the approach is rigorous, we evaluate the non-linear term based on the average reservoir pressure predicted from material balance....

  6. Working on new gas turbine cycle for heat pump drive

    E-print Network

    Oak Ridge National Laboratory

    pump centrifugal compressor through a magnetic coupling. As described by AiResearch's program manager in which the conventional re- ciprocating compressor has been replaced with a high speed centrifugal one DO NOT 16 0 REMOVE 16 Small recuperated gas turbine engine, design rated at 13 hp and 27% efficiency

  7. Average charge states of heavy and superheavy ions passing through a rarified gas: Theory and experiment

    NASA Astrophysics Data System (ADS)

    Khuyagbaatar, J.; Shevelko, V. P.; Borschevsky, A.; Düllmann, Ch. E.; Tolstikhina, I. Yu.; Yakushev, A.

    2013-10-01

    The average charge states q¯ of heavy and superheavy ions (atomic numbers Z=80-114) passing through He gas are studied experimentally and theoretically. Experimental data were measured at the gas-filled recoil separator, i.e., the TransActinide Separator and Chemistry Apparatus (TASCA) at GSI Darmstadt, for ion energies of a few hundred keV/u at gas pressures of 0.2 to 2.0 mbar. An attempt is made to describe experimental q¯ values by means of atomic calculations of the binding energies and electron-loss and electron-capture cross sections. The influence of the gas-density effect is included in the calculations. The calculated q¯ reproduce the experimental values for elements with Z=80-114 within 20%. A comparison with different semiempirical models is presented as well, including a local fit of high accuracy, which is often used in superheavy-element experiments to estimate the average charge states of heavy ions, e.g., at the gas-filled recoil separator TASCA. The q¯ values for elements with Z=115, 117, 119, and 120 at He-gas pressure of 0.8 mbar are predicted.

  8. Three-dimensional flow visualization in a centrifugal compressor 

    E-print Network

    Trevillion, William Lee

    1976-01-01

    . Meherwan P. Boyce The flow in a centrifugal compressor is an extremely complex three-dimensional phenomenon about which little is understood. This lack of understanding is a serious handicap in the design of centrifugal compressors... Page Comparision of theoretical predictions and experimental results of Senoo, et al ( 12 ) Laminar flow control device for a centrifugal compressor Design profile of hub, blades, and shroud Blade mounting system 13 5A 5B Top view of assembled...

  9. Investigation of flow in centrifugal impeller with tandem inducer 

    E-print Network

    Nishida, Akira

    1976-01-01

    resulted in significantly increased interest in flow problems related to centrifugal compressors. This is because a centrifugal compressor has a reasonably high efficiency, and can be compactly designed for a high pressure ratio per stage, also a... turbine among the elements. A one percent gain in compressor efficiency leads to approximately a three percent reduction in fuel consumption. It is necessary for' designers to understand the flow mechanism in a centrifugal impeller to obtain high...

  10. Effects of centrifugation on gonadal and adrenocortical steroids in rats

    NASA Technical Reports Server (NTRS)

    Kakihana, R.; Butte, J. C.

    1980-01-01

    Many endocrine systems are sensitive to external changes in the environment. Both the pituitary adrenal and pituitary gonadal systems are affected by stress including centrifugation stress. The effect of centrifugation on the pituitary gonadal and pituitary adrenocortical systems was examined by measuring the gonadal and adrenal steroids in the plasma and brain following different duration and intensity of centrifugation stress in rats. Two studies were completed and the results are presented. The second study was carried out to describe the developmental changes of brain, plasma and testicular testosterone and dihydrotestosterone in Sprague Dawley rats so that the effect of centrifugation stress on the pituitary gonadal syatem could be better evaluated in future studies.

  11. Autobalancing and FDIR for a space-based centrifuge prototype

    NASA Technical Reports Server (NTRS)

    Wilson, Edward; Mah, Robert W.

    2005-01-01

    This report summarizes centrifuge-related work performed at the Smart Systems Research Laboratory at NASA Ames Research Center's Computational Sciences Division from 1995 through 2003. The goal is to develop an automated system that will sense an imbalance (both static and dynamic3) in a centrifuge and issue control commands to drive counterweights to eliminate the effects of the imbalance. This autobalancing development began when the ISS centrifuge design was not yet finalized, and was designed to work with the SSRL Centrifuge laboratory prototype, constructed in 1993-1995. Significant differences between that prototype and the current International Space Station (ISS) Centrifuge design are that: the spin axis for the SSRL Centrifuge prototype can translate freely in x and y, but not wobble, whereas the ISS centrifuge spin axis has 3 translational and two rotational degrees of freedom, supported by a vibration 34. The imbalance sensors are strained gauges both in the rotor and the stator, measuring the imbalance forces, whereas the ISS centrifuge uses eddy current displacement sensors to measure the displacements resulting from imbalance. High fidelity autobalancing and FDIR systems (for both counterweights and strain gauges) are developed and tested in MATLAB simulation, for the SSRL Centrifuge configuration. Hardware implementation of the autobalancing technology was begun in 1996, but was terminated due to lack of funding. The project lay dormant until 2001-2002 when the FDIR capability was added.

  12. Incremental adaptation to yaw head movements during 30 RPM centrifugation

    E-print Network

    Elias, Paul Z. (Paul Ziad)

    2006-01-01

    Artificial Gravity (AG) provided by short-radius centrifugation is a promising countermeasure against the harmful physiological effects of prolonged weightlessness. However, the vestibular stimulus associated with making ...

  13. Cytoplasmic streaming in internodal cells of Nitella under centrifugal acceleration: a study done with a newly constructed centrifuge microscope

    Microsoft Academic Search

    E. Kamitsubo; Y. Ohashi; M. Kikuyama

    1989-01-01

    Summary We constructed a new centrifuge microscope of the stroboscopic type, with which the cytoplasmic streaming inNitella internodal cells under centrifugal acceleration was studied. Under moderate centrifugal acceleration (ca. 50–100×g), the direction of cytoplasmic streaming in an internodal cell ofNitella is parallel to the direction of the subcortical fibrils. The speed of endoplasm flowing contiguous to the subcortical fibrils is

  14. Effects of Prolonged Centrifugation on Orthostasis

    NASA Technical Reports Server (NTRS)

    Cohen, Malcolm M..; Hargens, A. R.; Yates, B. J.; Bowley, Susan M. (Technical Monitor)

    2000-01-01

    A feasibility study conducted on the Ames 20-G Human Centrifuge examined how well humans can maintain orthostatic tolerance during and after prolonged exposures to hypergravity. Three adult males lived for periods of 22 hours in the centrifuge while it was at rest (1.00 G), and while it rotated at 9.38 RPM to provide 1.25 G-total at the mean radius of 7.62 m. Two participants also experienced 22-hour habitation sessions at 11.46 RPM, which provided 1.50 G-total. Both before and after each habitation session, the participants were given gradual onset rate (GOR) acceleration profiles at 0.067 G/sec to determine their Gz tolerance. In addition, cardiovascular responses were compared while subjects were supine, siting, and standing at various times during the habitation (stand test), and cardiovascular responsiveness was determined using a lower body negative pressure tilt table (LBNPTT) at the beginning of the experiment and after each session. Post-Pre changes in G tolerance were -0.33 (mean) +/- 0.11 (std. error) Gz for habitation at 1.00 G, -0.02 +/- 0.12 Gz for habitation at 1.25 G, and +0.41 +/- 0.13 Gz for habitation at 1.50 G. Performance on the stand test generally improved with duration of habitation in hypergravity. Our results suggest that habitation in a confined chamber at 1.00 G reduces G tolerance and leads to lowered LBNPTT tolerance. Exposure to increased G in the centrifuge leads to enhanced performance on the stand test, and to increased GOR acceleration tolerance, but only when fluid balance is maintained; when motion sickness and negative fluid balance were observed, G tolerance was reduced. The data indicate that enhanced G tolerance can result from prolonged exposure to hypergravity, but that these changes are complex and depend on multiple underlying physiological processes.

  15. Centrifuge Modeling of Rainfall Induced Slope Failure

    NASA Astrophysics Data System (ADS)

    Ling, H.; Wu, M.

    2006-12-01

    Rainfall induces slope failure and debris flow which are considered as one of the major natural disasters. The scope of such failure is very large and it cannot be studied easily in the laboratory. Traditionally, small scale model tests are used to study such problem. Knowing that the behavior of soil is affected by the stress level, centrifuge modeling technique has been used to simulate more realistically full scale earth structures. In this study, two series of tests were conducted on slopes under the centrifugal field with and without the presence of rainfall. The soil used was a mixture of sand and 15 percent fines. The slopes of angle 60 degrees were prepared at optimum water content in order to achieve the maximum density. In the first series of tests, three different slope heights of 10 cm, 15 cm and 20 cm were used. The gravity was increased gradually until slope failure in order to obtain the prototype failure height. The slope model was cut after the test in order to obtain the configuration of failure surface. It was found that the slope geometry normalized by the height at failure provided unique results. Knowing the slope height or gravity at failure, the second series of tests with rainfall were conducted slightly below the critical height. That is, after attaining the desired gravity, the rainfall was induced in the centrifuge. Special nozzles were used and calibrated against different levels of gravity in order to obtain desired rainfall intensity. Five different rainfall intensities were used on the 15-cm slopes at 80g and 60g, which corresponded to 12 m and 9 m slope height, respectively. The duration until failure for different rainfall intensities was obtained. Similar to the first series of tests, the slope model was cut and investigated after the test. The results showed that the failure surface was not significantly affected by the rainfall. That is, the excess pore pressure induced by rainfall generated slope failure. The prediction curves of rainfall intensity versus duration were obtained from the test results. Such curves are extremely useful for disaster management. This study indicated feasibilities of using centrifuge modeling technique in simulating rainfall induced slope failure. The results obtained may also be used for validating numerical tools.

  16. Power transmission mechanism equipped with fluid and centrifugal clutch

    SciTech Connect

    Tamura, K.; Takeshita, S.; Fukunaga, T.

    1986-12-30

    This patent describes a power transmission mechanism equipped with a fluid coupling, an input shaft thereof interconnected to a power source being interconnected through the fluid coupling to an output shaft, and the output shaft being interconnected to a forward-rearward changeover mechanism including a speed changer. It is characterized in that the fluid coupling includes a shell, an impeller in the shell and a centrifugal clutch means in the shell for engaging the impeller and for driving the impeller when the shell is rotated by the input shaft at a speed above idle speed and for disengaging the impeller and the driving of the impeller when the shell is rotated by the input shaft at the idle speed. A turbine is included in the shell for standing idle in the shell when the centrifugal clutch means is disengaged and for drive by the impeller when the centrifugal clutch means is engaged and for driving the output shaft. The centrifugal clutch means comprises a support member fixed to the shell, a centrifugal shoe mounted on the support member for radial movement outwardly of the support member by centrifugal force and radial movement inwardly toward the support member. It also comprises spring means for moving the shoe inwardly toward the support member when the shell is rotated at idle speed, a cylindrical casing fixed to the impeller radially outward from the shoe and having an engaging surface for engagement by the centrifugal shoe when the shell is rotated at a speed above idle speed and the centrifugal shoe is moved radially outward by centrifugal force. The forward-rearward changeover mechanism, including the speed changer, is driven by the turbine when the centrifugal clutch means is engaged with the engaging surface and standing idle when the centrifugal clutch means is disengaged from the engaging surface and the turbine is standing idle.

  17. 77 FR 65360 - Grant of Authority for Subzone Status (Centrifugal and Submersible Pumps); Auburn, NY

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-10-26

    ...Subzone Status (Centrifugal and Submersible Pumps); Auburn, NY Pursuant to its authority...subzone at the centrifugal and submersible pump manufacturing and warehousing facilities...manufacturing of centrifugal and submersible pumps and related controllers at the Xylem...

  18. 21 CFR 864.9275 - Blood bank centrifuge for in vitro diagnostic use.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ...false Blood bank centrifuge for in vitro diagnostic use. 864.9275 Section...9275 Blood bank centrifuge for in vitro diagnostic use. (a) Identification. A blood bank centrifuge for in vitro diagnostic use is a device used...

  19. Settling velocities of particulate systems: 14. Unified model of sedimentation, centrifugation

    E-print Network

    Bürger, Raimund

    Settling velocities of particulate systems: 14. Unified model of sedimentation, centrifugation­liquid separation of flocculated suspensions including sedimentation- thickening, centrifugation and filtration. After identifying the variables and equations for each of the operations, thickening, centrifugation

  20. 21 CFR 864.9275 - Blood bank centrifuge for in vitro diagnostic use.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ...2013-04-01 false Blood bank centrifuge for in vitro diagnostic use...Products § 864.9275 Blood bank centrifuge for in vitro diagnostic use. (a) Identification. A blood bank centrifuge for in vitro diagnostic use...

  1. Centrifugal devices can replace traditional separation techniques such as column chromatography, preparative

    E-print Network

    Lebendiker, Mario

    Centrifugal devices can replace traditional separation techniques such as column chromatography, preparative electrophoresis, alcohol or salt precipitation, dialysis, and gradient centrifugation when. Centrifugal Devices for Ultrafiltration & Microfiltration Nanosep®, MicrosepTM, Macrosep®, and Jumbosep

  2. Centrifuge Permeameter for Unsaturated Soils. II: Measurement of the Hydraulic Characteristics

    E-print Network

    Zornberg, Jorge G.

    Centrifuge Permeameter for Unsaturated Soils. II: Measurement of the Hydraulic Characteristics and hydraulic conductivity function K function , determined using a new centrifuge permeameter developed hydraulic characteristics of the compacted clay. The SWRCs and K functions defined using the centrifuge

  3. Centrifugal force induced by relativistically rotating spheroids and cylinders

    E-print Network

    Joseph Katz; Donald Lynden-Bell; Jiri Bicak

    2011-02-25

    Starting from the gravitational potential of a Newtonian spheroidal shell we discuss electrically charged rotating prolate spheroidal shells in the Maxwell theory. In particular we consider two confocal charged shells which rotate oppositely in such a way that there is no magnetic field outside the outer shell. In the Einstein theory we solve the Ernst equations in the region where the long prolate spheroids are almost cylindrical; in equatorial regions the exact Lewis "rotating cylindrical" solution is so derived by a limiting procedure from a spatially bound system. In the second part we analyze two cylindrical shells rotating in opposite directions in such a way that the static Levi-Civita metric is produced outside and no angular momentum flux escapes to infinity. The rotation of the local inertial frames in flat space inside the inner cylinder is thus exhibited without any approximation or interpretational difficulties within this model. A test particle within the inner cylinder kept at rest with respect to axes that do not rotate as seen from infinity experiences a centrifugal force. Although the spacetime there is Minkowskian out to the inner cylinder nevertheless that space has been induced to rotate, so relative to the local inertial frame the particle is traversing a circular orbit.

  4. DIFFUSION THEORY IMPROVES CHAMBER-BASED MEASUREMENTS OF TRACE GAS EMISSIONS

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Chambers temporarily sealed to the soil surface are an important and for many purposes the only means of measuring trace gas emissions to the atmosphere. However, past interpretations of chamber data systematically underestimated actual emission rates in most applications because they ignored or poo...

  5. High speed active gas\\/odor sensing system using adaptive control theory

    Microsoft Academic Search

    T. Nakamoto; N. Okazaki; T. Mornzumi

    1997-01-01

    An active gas\\/odor sensing system using an internal blender was previously proposed to measure the mixture composition of an aroma. In the system, the mixture composition of the blender outlet was repeatedly adjusted using an optimization algorithm to match the sensor array output pattern of blended vapor to that of a test vapor. The system is highly flexible and can

  6. Centrifugation of coal-derived liquids

    SciTech Connect

    Weintraub, Murray; Weiss, Milton L.; Akhtar, Sayeed

    1980-06-01

    The application of the continuous solid bowl centrifuge to the removal of solids from coal liquefaction products was investigated. The centrifuge removed from 23 to 88% of the input ash from 8 to 73% of the input organic benzene insolubles while flow rates, viscosities, and dam heights were varied. Viscosity ..mu.., effluent liquid rate Q/sub e/, and Ambler's geometric parameter ..sigma.. were graphically correlated with attained separations. The separation was relatively insensitive to the variables, as a 50-fold increase in Q/sub e//..sigma.. corresponded to a decrease in ash removal only from 84% to 60% and to a decrease in organic solids removal only from 77% to 22%. Organic solids removal was poorer and more erratic than ash removal because of the lesser density differences and greater size variability of the organics. Ancillary studies demonstrated that coal liquefaction products may behave as a Bingham Plastic fluid, and that this results in an absolute limit on the attainable solids separation. Additional studies showed that little difference in density may exist between the organic solids and liquids, and that effects of aging may threaten the validity of viscosity measurements.

  7. Experimental Investigation of Centrifugal Compressor Stabilization Techniques

    NASA Technical Reports Server (NTRS)

    Skoch, Gary J.

    2003-01-01

    Results from a series of experiments to investigate techniques for extending the stable flow range of a centrifugal compressor are reported. The research was conducted in a high-speed centrifugal compressor at the NASA Glenn Research Center. The stabilizing effect of steadily flowing air-streams injected into the vaneless region of a vane-island diffuser through the shroud surface is described. Parametric variations of injection angle, injection flow rate, number of injectors, injector spacing, and injection versus bleed were investigated for a range of impeller speeds and tip clearances. Both the compressor discharge and an external source were used for the injection air supply. The stabilizing effect of flow obstructions created by tubes that were inserted into the diffuser vaneless space through the shroud was also investigated. Tube immersion into the vaneless space was varied in the flow obstruction experiments. Results from testing done at impeller design speed and tip clearance are presented. Surge margin improved by 1.7 points using injection air that was supplied from within the compressor. Externally supplied injection air was used to return the compressor to stable operation after being throttled into surge. The tubes, which were capped to prevent mass flux, provided 9.3 points of additional surge margin over the baseline surge margin of 11.7 points.

  8. Wave Augmented Diffusers for Centrifugal Compressors

    NASA Technical Reports Server (NTRS)

    Paxson, Daniel E.; Skoch, Gary J.

    1998-01-01

    A conceptual device is introduced which would utilize unsteady wave motion to slow and turn flows in the diffuser section of a centrifugal compressor. The envisioned device would substantially reduce the size of conventional centrifugal diffusers by eliminating the relatively large ninety degree bend needed to turn the flow from the radial/tangential to the axial direction. The bend would be replaced by a wall and the flow would instead exit through a series of rotating ports located on a disk, adjacent to the diffuser hub, and fixed to the impeller shaft. The ports would generate both expansion and compression waves which would rapidly transition from the hub/shroud (axial) direction to the radial/tangential direction. The waves would in turn induce radial/tangential and axial flow. This paper presents a detailed description of the device. Simplified cycle analysis and performance results are presented which were obtained using a time accurate, quasi-one-dimensional CFD code with models for turning, port flow conditions, and losses due to wall shear stress. The results indicate that a periodic wave system can be established which yields diffuser performance comparable to a conventional diffuser. Discussion concerning feasibility, accuracy, and integration follow.

  9. Overview of the Maryland Centrifugal Experiment

    NASA Astrophysics Data System (ADS)

    Ellis, Richard; Choi, Seungho; Clary, Ryan; Elton, Raymond; Hassam, Adil; Talamas, Carlos; Teodorescu, Catalin; Uzun-Kaymak, Ilker; Messer, Sarah; Case, Andrew; Witherspoon, Douglas

    2008-11-01

    Recent results on MCX include : a) further measurements of ion rotational velocity profiles demonstrate shear in the rotation that exceeds the critical value for shear stabilization; b) a new insulator has eliminated the transition from high-rotation mode to low rotation mode; c) a study of the scaling of maximum rotational velocity shows that it is clearly limited from above by the Alfven velocity - the CIV limit is under study; d) magnetic probe measurements show that B fluctuations are dominated by a spectrum of low m number modes, indicating all high m modes are stabilized by velocity shear ; e) diamagnetic loop measurements at a variety of axial locations, and corresponding MHD analysis, are consistent with centrifugal confinement; f ) a new plasma injection gun has been installed and tested on MCX; injection experiments will be reported; g) a new 16 chord Halpha array has been implemented and an off center IR interferometer is almost complete for confirming centrifugal confinement. Upgrade plans will also be discussed.

  10. Fundamentals and application of centrifugal pumps for the practicing engineer

    Microsoft Academic Search

    Benaroya

    1978-01-01

    A reference work on the application of centrifugal pumps to pipelining, refining, or oil production and gathering systems is presented. The contents include: pressure loss due to friction; energy loss; compound pipes in series; compound pipes in parallel; energy required to transfer liquids; the centrifugal pump; characteristic pump curves; evaluation of manufacturers' pump performance characteristics; variation of pump curves; operating

  11. CENTRIPETAL ACCELERATION AND CENTRIFUGAL FORCE IN GENERAL RELATIVITY

    E-print Network

    Jantzen, Robert T.

    1 CENTRIPETAL ACCELERATION AND CENTRIFUGAL FORCE IN GENERAL RELATIVITY D. BINI Istituto per mechanics non-inertial observers studying accelerated test particle motion experience a centripetal acceleration which, once interpreted as a centrifugal force acting on the particle, allows writing the particle

  12. Modelling of horizontal centrifugal casting of work roll

    Microsoft Academic Search

    Zhian Xu; Nannan Song; Rob Val Tol; Yikun Luan; Dianzhong Li

    2012-01-01

    A numerical model to simulate horizontal centrifugal roll castings is presented in this paper. In order to simulate the flow fluid and solidification of horizontal centrifugal roll casting correctly, the model uses a body fitted mesh technique to represent the geometry. This new method maps a plate layer mesh to a circular mesh. The smooth body fitted mesh method gives

  13. Effects of centrifugal drift on hurricane structure and intensity

    Microsoft Academic Search

    G. J. Tripoli; T. Hashino; W. Lewis

    2009-01-01

    High (1km) resolution simulations of the 2005 hurricane Wilma were conducted using the UW-NMS which models the effect of horizontal precipitation drift due to centrifugal force. The extremely tight nature of Wilma's vortex suggests that there should be a measurable horizontal drift of precipitation, comparable to the vertical motion, that is due to centrifugal terminal velocity. These effects would likely

  14. A centrifugal pump concept designed for multiple use in space

    Microsoft Academic Search

    E. Wunderlich; H. G. Wulz

    1993-01-01

    A centrifugal pump concept was elaborated for a multiple application in future spacecrafts. Based on this concept a prototype of a small centrifugal pump was manufactured and comprehensively tested. The model pump has been approved in different test series with the fluids liquid ammonia and demineralized water. The design of the model pump was driven by strict requirements of COLUMBUS,

  15. AN AERODYNAMIC-THERMODYNAMIC STUDY OF CENTRIFUGAL COMPRESSORS

    Microsoft Academic Search

    1962-01-01

    A procedure is presented for the aerodynamic and thermodynamic design of ; centrifugal compressors. Design equations are derived from basic laws of ; thermodynamics and fluid flow where possible. The experimental data and much of ; the mathematical treatment comes from the extensive literature on centrifugal ; compressors. An attempt has been made to assemble the bits of information which

  16. Development of a Low Flow Coefficient Single Stage Centrifugal Compressor

    Microsoft Academic Search

    C. Xu; R. S. Amano

    2009-01-01

    A low flow coefficient unshrouded centrifugal compressor would give up clearance in relation to the span of the blades, because centrifugal compressors produce a sufficiently large pressure rise in fewer stages. This problem is more acute for a low flow high-pressure ratio impeller. The large tip clearance would cause flow separations, and as a result it would drop both the

  17. Modeling for surge control of centrifugal compresssors: comparison with experiment

    E-print Network

    Gravdahl, Jan Tommy

    con- trol design, of a centrifugal compression system is vali- dated. Compressor surge is an unwanted to an actuator, and the unstable area of the compressor map can be stabilized. In designing the active surge to centrifugal compressors. Since compressors are vari- able speed machines, and surge is commonly encoun- tered

  18. Operation of Centrifugal Compressor as Annular Array of Blading

    Microsoft Academic Search

    G. A. Bykov; O. G. Bykova

    2005-01-01

    We demonstrate that the polytropic efficiency of modern centrifugal compressors can be raised to the level reached by axial-flow\\u000a compressors. We consider systems of circulation flows around the impeller, the flows past the blading of axial and centrifugal\\u000a compressors. And we make recommendations for the compressor blade design.

  19. BOND OF PRESTRESSING STRAND IN CENTRIFUGALLY CAST CONCRETE

    Microsoft Academic Search

    Ian E. Hosch; Fouad H. Fouad; Ronald Albanese

    Centrifugally cast concrete (aka, spun concrete) is a process of concrete placement that involves significant compaction and consolidations during the spinning process. The process is applied in the manufacture of specialized precast products such as pipe, poles, and piles. This study concentrates on bond characteristics of prestressing steel in centrifugally cast prestressed concrete. The prestressing strands are anchored before transferring

  20. Synaptic Connections of the Centrifugal Fibers in the Pigeon Retina

    Microsoft Academic Search

    H. R. Maturana; S. Frenk

    1965-01-01

    The centrifugal fibers in the pigeon retina end in the inner nuclear layer and form two kinds of terminals, convergent and divergent. In the inner nuclear layer the fibers synapse with amacrine and displaced ganglion cells. Because of their great number and their even distribution these fibers appear to constitute a system for the localized centrifugal control of the retinal

  1. Blending silica bodies in centrifugal runner mills, “model 115”

    Microsoft Academic Search

    I. T. Gubko; I. D. Sizov; M. I. Kostomarov; E. V. Khitro

    1963-01-01

    Conclusions The output of “model 115” centrifugal runner mills for mixing dinas bodies is 1.7 times higher than that of runner mills with heavy rollers. Goods pressed from bodies prepared in centrifugal runner mills are no different in quality from those pressed from bodies made in runner mills with heavy rollers. The difference in output of acceptable product is slight.

  2. Centrifugal Barrel Finishing Of Turbine-Blade "Fir Trees"

    NASA Technical Reports Server (NTRS)

    Mandel, Johnny L.

    1990-01-01

    Modified centrifugal barrel-finishing machine imparts desired residual compressive stresses to "fir trees" of turbine blades. Centrifugal forces generate compressive stresses, which are transmitted to turbine blades through abrasive slurries in which suspended. Eliminates need for shot peening, rounding of edges and burrs caused by shot peening and, consequently, need for mass finishing operations to remove burrs. Improves surface finish of "fir trees".

  3. Creating porous tubes by centrifugal forces for soft tissue application

    Microsoft Academic Search

    Paul D. Dalton; Molly S. Shoichet

    2001-01-01

    Chemically crosslinked poly(2-hydroxyethyl methacrylate) (PHEMA) tubes were synthesized by applying centrifugal forces to propagating polymer chains in solution. Initiated monomer solutions, with a composition typical for PHEMA sponges, were placed into a cylindrical mold that was rotated about its long axis. As polymerization proceeded, phase separated PHEMA formed a sediment at the periphery under centrifugal action. The solvent remained in

  4. Novel Kinetic Theory of the Classical Isotropic Oscillator Gas, the Flexible Shell Model

    NASA Astrophysics Data System (ADS)

    Schruben, Dale

    2013-12-01

    Ever since Chapman and Enskog first used the hard sphere model to evaluate the collision integral in the Boltzmann equation, more sophisticated models for molecular encounters have been sought. Rotation of molecules in kinetic theory has been pursued with a number of models, such as the spherocylinder or loaded sphere, to account for that aspect. As these efforts continued, more workers started to incorporate quantum mechanics methods in pursuit of solutions to the Boltzmann equation. Progress there with both rotational and vibrational features of molecules has been attained. Until now though, there has been no classical vibration model for molecules in kinetic theory. Far from standard kinetic theory, here a simple classical mechanics isotropic oscillator is combined, through a flexible shell, with the hard sphere model in a full Chapman Enskog procedure. The intent here has been to introduce the model, so items like translational-vibrational coupling have not been included. Still, the results compliment literature.

  5. Effect of science laboratory centrifuge of space station environment

    NASA Technical Reports Server (NTRS)

    Searby, Nancy

    1990-01-01

    It is argued that it is essential to have a centrifuge operating during manned space station operations. Background information and a rationale for the research centrifuge are given. It is argued that we must provide a controlled acceleration environment for comparison with microgravity studies. The lack of control groups in previous studies throws into question whether the obseved effects were the result of microgravity or not. The centrifuge could be used to provide a 1-g environment to supply specimens free of launch effects for long-term studies. With the centrifuge, the specimens could be immediately transferred to microgravity without undergoing gradual acclimation. Also, the effects of artificial gravity on humans could be investigated. It is also argued that the presence of the centrifuge on the space station will not cause undo vibrations or other disturbing effects.

  6. Modeling centrifugal cell washers using computational fluid dynamics.

    PubMed

    Kellet, Beth E; Han, Binbing; Dandy, David S; Wickramasinghe, S Ranil

    2004-11-01

    Reinfusion of shed blood during surgery could avoid the need for blood transfusions. Prior to reinfusion of the red blood cells, the shed blood must be washed in order to remove leukocytes, platelets, and other contaminants. Further, the hematocrit of the washed blood must be increased. The feasibility of using computational fluid dynamics (CFD) to guide the design of better centrifuges for processing shed blood is explored here. The velocity field within a centrifuge bowl and the rate of protein removal from the shed blood has been studied. The results obtained indicate that CFD could help screen preliminary centrifuge bowl designs, thus reducing the number of initial experimental tests required when developing new centrifuge bowls. Although the focus of this work is on washing shed blood, the methods developed here are applicable to the design of centrifuge bowls for other blood-processing applications. PMID:15504118

  7. A renormalized Gross Pitaevskii theory and vortices in a strongly interacting Bose gas

    NASA Astrophysics Data System (ADS)

    Moseley, Ch; Ziegler, K.

    2007-02-01

    We consider a strongly interacting Bose-Einstein condensate in a spherical harmonic trap. The system is treated by applying a slave-boson representation for hardcore bosons. A renormalized Gross-Pitaevskii theory is derived for the condensate wavefunction that describes the dilute regime (like the conventional Gross-Pitaevskii theory) as well as the dense regime. We calculate the condensate density of a rotating condensate for both the vortex-free condensate and the condensate with a single vortex and determine the critical angular velocity for the formation of a stable vortex in a rotating trap.

  8. Centrifugal compressor modifications and their effect on high-frequency pipe wall vibration

    SciTech Connect

    Motriuk, R.W.; Harvey, D.P. [Nova Gas Transmission Ltd., Calgary, Alberta (Canada)

    1998-08-01

    High-frequency pulsation generated by centrifugal compressors, with pressure wave-lengths much smaller than the attached pipe diameter, can cause fatigue failures of the compressor internals, impair compressor performance, and damage the attached compressor piping. There are numerous sources producing pulsation in centrifugal compressors. Some of them are discussed in literature at large (Japikse, 1995; Niese, 1976). NGTL has experienced extreme high-frequency discharge pulsation and pipe wall vibration on many of its radial inlet high-flow centrifugal gas compressor facilities. These pulsations led to several piping attachment failures and compressor internal component failures while the compressor operated within the design envelope. This paper considers several pulsation conditions at an NGTL compression facility which resulted in unacceptable piping vibration. Significant vibration attenuation was achieved by modifying the compressor (pulsation source) through removal of the diffuser vanes and partial removal of the inlet guide vanes (IGV). Direct comparison of the changes in vibration, pulsation, and performance are made for each of the modifications. The vibration problem, probable causes, options available to address the problem, and the results of implementation are reviewed. The effects of diffuser vane removal on discharge pipe wall vibration as well as changes in compressor performance are described.

  9. A covariant Fokker-Planck equation for a simple gas from relativistic kinetic theory

    SciTech Connect

    Chacon-Acosta, Guillermo; Dagdug, Leonardo; Morales-Tecotl, Hugo A. [Departamento de Fisica, Universidad Autonoma Metropolitana-Iztapalapa, Mexico D. F. 09340 (Mexico)

    2010-12-14

    A manifestly covariant Fokker-Planck differential equation is derived for the case of a relativistic simple gas by taking a small momentum transfer approximation within the collision integral of the relativistic Boltzmann equation. We follow closely previous work, with the main difference that we keep manifest covariance at every stage of the analysis. In addition, we use the covariant Juettner distribution function to find a relativistic generalization of the Einstein's fluctuation-dissipation relation.

  10. Theory of nuclear pumped noble gas lasers and comparison with experiment

    Microsoft Academic Search

    J. E. Deese; H. A. Hassan

    1979-01-01

    A general model is proposed for the analysis of nuclear pumped noble gas lasers. Results obtained with this model are used to study (He-3)-Xe systems pumped by the He-3(n,p)H-3 reaction. The calculated small signal gain coefficient and power output are in good agreement with available experiment. It is concluded that both direct excitation and recombination play an important part in

  11. Photoabsorption to Stark Rydberg States of Heavy Noble Gas Atoms: Testing Limits of Closed Orbit Theory

    Microsoft Academic Search

    Heric Flores-Rueda; Matthew L. Keeler; David Wright; Thomas J. Morgan

    2003-01-01

    The selective dramatic effects of a dc electric field on the photoabsorption spectrum of Rydberg states and the associated recurrence strengths and closed orbits are studied in heavy noble gas atoms. Using collinear atom-laser beam spectroscopy, complex scaled-energy photoabsorption spectra are mapped experimentally in high resolution for pi and sigma transitions from the ns[3\\/2] and ns[1\\/2] metastable states, formed by

  12. Lattice gas hydrodynamics: Theory and simulations. Final report, [February 1, 1989--March 31, 1991

    SciTech Connect

    Hasslacher, B.

    1993-05-01

    The first successful application of a microscopic analogy to create a skeleton cellular automaton and analyze it with statistical mechanical tools, was the work of Frisch, Hasslacher and Pomeau on the Navier-Stokes equation in two and three dimensions. This has become a very large research area with lattice gas models and methods being used for both fundamental investigations into the foundations of statistical mechanics and a large number of diverse applications. This present research was devoted to enlarging the fundamental scope of lattice gas models and proved successful. Since the beginning of this proposal, cellular automata have been constructed for statistical mechanical models, fluids, diffusion and shock systems in fundamental investigations. In applied areas, there are now excellent lattice gas models for complex flows through porous media, chemical reaction and combustion dynamics, multiphase flow systems, and fluid mixtures with natural boundaries. With extended cellular fluid models, one can do problems with arbitrary pairwise potentials. Recently, these have been applied to such problems as non-newtonian or polymeric liquids and a mixture of immiscible fluids passing through fractal or spongelike media in two and three dimensions. This proposal has contributed to and enlarged the scope of this work.

  13. Separation Control in a Centrifugal Bend Using Plasma Actuators

    NASA Astrophysics Data System (ADS)

    Arthur, Michael; Corke, Thomas

    2011-11-01

    An experiment and CFD simulation are presented to examine the use of plasma actuators to control flow separation in a 2-D channel with a 135° inside-bend that is intended to represent a centrifugal bend in a gas turbine engine. The design inlet conditions are P = 330 psia., T =1100° F, and M = 0 . 24 . For these conditions, the flow separates on the inside radius of the bend. A CFD simulation was used to determine the location of the flow separation, and the conditions (location and voltage) of a plasma actuator that was needed to keep the flow attached. The plasma actuator body force model used in the simulation was updated to include the effect of high-pressure operation. An experiment was used to validate the simulation and to further investigate the effect of inlet pressure and Mach number on the flow separation control. This involved a transient high-pressure blow-down facility. The flow field is documented using an array of static pressure taps in the channel outside-radius side wall, and a rake of total pressure probes at the exit of the bend. The results as well as the pressure effect on the plasma actuators are presented.

  14. Developments in centrifugal compressor surge control: A technology assessment

    NASA Astrophysics Data System (ADS)

    Botros, K. K.; Henderson, J. F.

    1994-04-01

    There are a number of surge control schemes in current use for centrifugal compressors employed in natural gas transmission systems. Basically, these schemes consist of a set of detection devices that either anticipate surge or detect it at its inception, and a set of control devices that act to prevent surge from occurring. A patent search was conducted in an attempt to assess the level and direction of technology development over the last 20 years and to define the focus for future R&D activities. In addition, the paper presents the current state of technology in three areas: surge control, surge detection, and surge suppression. Patent data obtained from on-line databases showed that most of the emphasis has been on surge control rather than on detection and control and that the current trend in surge control will likely continue toward incremental improvement of a basic or conventional surge control strategy. Various surge suppression techniques can be grouped in two categories: (i) those that are focused on better compressor interior design, and (ii) others that attempt to suppress surge by external and operational means.

  15. Developments in a centrifugal compressor surge control -- a technology assessment

    SciTech Connect

    Botros, K.K.; Henderson, J.F. (NOVACOR Research Technology Corp., Calgary, Alberta (Canada))

    1994-04-01

    There are a number of surge control schemes in current use for centrifugal compressors employed in natural gas transmission systems. Basically, these schemes consist of a set of detection devices that either anticipate surge or detect it at its inception, and a set of control devices that act to prevent surge from occurring. A patent search was conducted in an attempt to assess the level and direction of technology development over the last 20 years and to define the focus for future R D activities. In addition, the paper presents the current state of technology in three areas: surge control, surge detection, and surge suppression. Patent data obtained from on-line databases showed that most of the emphasis has been on surge control rather than on detection and control and that the current trend in surge control will likely continue toward incremental improvement of a basic or conventional surge control strategy. Various surge suppression techniques can be grouped in two categories: (1) those that are focused on better compressor interior design, and (2) others that attempt to suppress surge by external and operational means.

  16. Application of centrifugal compressors to pressure decline

    Microsoft Academic Search

    Hammel; A. J. Jr

    1973-01-01

    A partial map is shown of the U.S. pressure decline fields. These include the San Juan pressure decline, the Lea County pressure decline, and Delaware Basin pressure decline. The depletion of gas reserves now being talked about so frequently actually starts as soon as gas is removed from a reservoir. The usual means of coping with the depletion of gas

  17. Rotordynamic forces on centrifugal pump impellers

    NASA Technical Reports Server (NTRS)

    Franz, R.; Arndt, N.; Caughey, T. K.; Brennen, C. E.; Acosta, A. J.

    1987-01-01

    The asymmetric flow around an impeller in a volute exerts a force upon the impeller. To study the rotordynamic force on an impeller which is vibrating around its machine axis of rotation, the impeller, mounted on a dynamometer, is made to whirl in a circular orbit within the volute. The measured force is expressed as the sum of a steady radial force and an unsteady force due to the eccentric motion of the impeller. These forces were measured in separate tests on a centrifugal pump with radically increased shroud clearance, a two-dimensional impeller, and an impeller with an inducer, the impeller of the HPOTP (High Pressure Oxygen Turbopump) of the SSME (Space Shuttle Main Engine). In each case, a destabilizing force was observed over a region of positive whirl.

  18. Numerical simulation of centrifugal casting of pipes

    NASA Astrophysics Data System (ADS)

    Kaschnitz, E.

    2012-07-01

    A numerical simulation model for the horizontal centrifugal pipe casting process was developed with the commercial simulation package Flow3D. It considers - additionally to mass, energy and momentum conservation equations and free surface tracking - the fast radial and slower horizontal movement of the mold. The iron inflow is not steady state but time dependent. Of special importance is the friction between the liquid and the mold in connection with the viscosity and turbulence of the iron. Experiments with the mold at controlled revolution speeds were carried out using a high-speed camera. From these experiments friction coefficients for the description of the interaction between mold and melt were obtained. With the simulation model, the influence of typical process parameters (e.g. melts inflow, mold movement, melt temperature, cooling media) on the wall thickness of the pipes can be studied. The comparison to results of pipes from production shows a good agreement between simulation and reality.

  19. Recent advances in centrifugal contactors design

    SciTech Connect

    Leonard, R.A.

    1987-10-01

    Advances in thedesign of the Argonne centrifugal contactor for solvent extaction are being realized as these contactors are built, tested, and used to implement the TRUEX process for the cleanup of nuclear waste liquids. These advances include (1) using off-the-shelf, face-mounted motors, (2) modifying the contractor so that relatively volatile solvents can be used, (3) adding a high-level liquid detector that can be used to alert the plant operator of process upsets, (4) providing secondary feed ports, (5) optimizing support frame design, (6) maintaining a linear design with external interstage lines so the stages can be allocated as needed for extraction, scrub, strip, and solvent cleanup operations, and (7) developing features that facilitate contractor operation in remote facilities. 11 refs., 8 figs.

  20. A modeling study of a centrifugal compressor

    SciTech Connect

    Popovic, P.; Shapiro, H.N. [Iowa State Univ., Ames, IA (United States). Dept. of Mechanical Engineering

    1998-12-31

    A centrifugal compressor, which is part of a chlorofluorocarbon R-114 chiller installation, was investigated, operating with a new refrigerant, hydrofluorocarbon R-236ea, a proposed alternative to R-114. A large set of R-236ea operating data, as well as a limited amount of R-114 data, were available for this study. A relatively simple analytical compressor model was developed to describe compressor performance. The model was built upon a thorough literature search, experimental data, and some compressor design parameters. Two original empirical relations were developed, providing a new approach to the compressor modeling. The model was developed in a format that would permit it to be easily incorporated into a complete chiller simulation. The model was found to improve somewhat on the quantitative and physical aspects of a compressor model of the same format found in the literature. It was found that the compressor model is specific to the particular refrigerant.

  1. Asynchronous vibration problem of centrifugal compressor

    NASA Technical Reports Server (NTRS)

    Fujikawa, T.; Ishiguro, N.; Ito, M.

    1980-01-01

    An unstable asynchronous vibration problem in a high pressure centrifugal compressor and the remedial actions against it are described. Asynchronous vibration of the compressor took place when the discharge pressure (Pd) was increased, after the rotor was already at full speed. The typical spectral data of the shaft vibration indicate that as the pressure Pd increases, pre-unstable vibration appears and becomes larger, and large unstable asynchronous vibration occurs suddenly (Pd = 5.49MPa). A computer program was used which calculated the logarithmic decrement and the damped natural frequency of the rotor bearing systems. The analysis of the log-decrement is concluded to be effective in preventing unstable vibration in both the design stage and remedial actions.

  2. Centrifugal governor for internal combustion engines

    SciTech Connect

    Ohnishi, M.

    1986-09-23

    A centrifugal governor is described for use with an internal combustion engine which consists of: a control rack for regulating the quantity of fuel to be supplied to the engine; flyweights radially displaceable in response to the rotational speed of the engine; a tension lever pivotable through an angle dependent upon the amount of radial displacement of the flyweights; an idling spring for urging the tension lever against radially outward displacement of the flyweights; a torque cam having a cam surface determining a fuel increment to be applied at the start of the engine; a sensor lever having one end engaged by the control rack, and another end adapted to engage with the cam surface of the torque cam; a cancelling spring interposed between the torque cam and the tension lever; a control lever; a floating lever interlocking with the control lever; and spring force adjusting means arranged at one end of the idling spring.

  3. Centrifuge impact cratering experiments: Scaling laws for non-porous targets

    NASA Technical Reports Server (NTRS)

    Schmidt, Robert M.

    1987-01-01

    This research is a continuation of an ongoing program whose objective is to perform experiments and to develop scaling relationships for large body impacts onto planetary surfaces. The development of the centrifuge technique has been pioneered by the present investigator and is used to provide experimental data for actual target materials of interest. With both powder and gas guns mounted on a rotor arm, it is possible to match various dimensionless similarity parameters, which have been shown to govern the behavior of large scale impacts. Current work is directed toward the determination of scaling estimates for nonporous targets. The results are presented in summary form.

  4. Experimental characterization of high speed centrifugal compressor aerodynamic forcing functions

    NASA Astrophysics Data System (ADS)

    Gallier, Kirk

    The most common and costly unexpected post-development gas turbine engine reliability issue is blade failure due to High Cycle Fatigue (HCF). HCF in centrifugal compressors is a coupled nonlinear fluid-structure problem for which understanding of the phenomenological root causes is incomplete. The complex physics of this problem provides significant challenges for Computational Fluid Dynamics (CFD) techniques. Furthermore, the available literature fails to address the flow field associated with the diffuser potential field, a primary cause of forced impeller vibration. Because of the serious nature of HCF, the inadequacy of current design approaches to predict HCF, and the fundamental lack of benchmark experiments to advance the design practices, there exists a need to build a database of information specific to the nature of the diffuser generated forcing function as a foundation for understanding flow induced blade vibratory failure. The specific aim of this research is to address the fundamental nature of the unsteady aerodynamic interaction phenomena inherent in high-speed centrifugal compressors wherein the impeller exit flow field is dynamically modulated by the vaned diffuser potential field or shock structure. The understanding of this unsteady aerodynamic interaction is fundamental to characterizing the impeller forcing function. Unsteady static pressure measurement at several radial and circumferential locations in the vaneless space offer a depiction of pressure field radial decay, circumferential variation and temporal fluctuation. These pressure measurements are coupled with high density, full field measurement of the velocity field within the diffuser vaneless space at multiple spanwise positions. The velocity field and unsteady pressure field are shown to be intimately linked. A strong momentum gradient exiting the impeller is shown to extend well across the vaneless space and interact with the diffuser vane leading edge. The deterministic unsteady pressure field is found to be dominated by the blade-vane interaction. HCF concerns are illuminated by persistent pressure waves extending radially across the vaneless space and impacting the impeller pressure surface. Finally, the average impeller exit flow field is found to present a highly unsteady velocity field to the downstream vane row, challenging the common design assumption of a rapid mixing model for diffuser design.

  5. A complete theory for the magnetism of an ideal gas of electrons

    SciTech Connect

    Biswas, Shyamal; Jana, Debnarayan [Department of Physics, University of Calcutta, 92 APC Road, Kolkata 700009 (India)] [Department of Physics, University of Calcutta, 92 APC Road, Kolkata 700009 (India); Sen, Swati [Department of Physical Sciences, Indian Institute of Science Education and Research-Kolkata, Mohanpur 741252 (India)] [Department of Physical Sciences, Indian Institute of Science Education and Research-Kolkata, Mohanpur 741252 (India)

    2013-05-15

    We have explored Pauli paramagnetism, Landau diamagnetism, and de Haas-van Alphen effect in a single framework, and unified these three effects for all temperatures as well as for all strengths of magnetic field. Our result goes beyond Pauli-Landau result on the magnetism of the 3-D ideal gas of electrons, and is able to describe crossover of the de Haas-van Alphen oscillation to the saturation of magnetization. We also have obtained a novel asymptotic series expansion for the low temperature properties of the system.

  6. Coupled-cluster theory of a gas of strongly-interacting electrons in the dilute limit

    SciTech Connect

    Mihaila, Bodgan [Los Alamos National Laboratory; Cardenas, Andres L [Los Alamos National Laboratory

    2008-01-01

    We study the ground-state properties of a dilute gas of strongly-interacting fermions in the framework of the coupled-cluster expansion (CCE). We demonstrate that properties such as universality, opening of a gap in the excitation spectrum and applicability of s-wave approximations appear naturally in the CCE approach. In the zero-density limit, we show that the ground-state energy density depends on only one parameter which in turn may depend at most on the spatial dimensionality of the system.

  7. A Unified Theory of Non-Ideal Gas Lattice Boltzmann Models

    NASA Technical Reports Server (NTRS)

    Luo, Li-Shi

    1998-01-01

    A non-ideal gas lattice Boltzmann model is directly derived, in an a priori fashion, from the Enskog equation for dense gases. The model is rigorously obtained by a systematic procedure to discretize the Enskog equation (in the presence of an external force) in both phase space and time. The lattice Boltzmann model derived here is thermodynamically consistent and is free of the defects which exist in previous lattice Boltzmann models for non-ideal gases. The existing lattice Boltzmann models for non-ideal gases are analyzed and compared with the model derived here.

  8. Density Functional Theory and Reaction Kinetics Studies of the Water–Gas Shift Reaction on Pt–Re Catalysts

    SciTech Connect

    Carrasquillo-Flores, Ronald; Gallo, Jean Marcel R.; Hahn, Konstanze; Dumesic, James A.; Mavrikakis, Manos

    2013-12-01

    Periodic, self-consistent density functional theory calculations (DFT-GGA-PW91) on Pt(111) and Pt3Re(111) surfaces, reaction kinetics measurements, and microkinetic modeling are employed to study the mechanism of the water–gas shift (WGS) reaction over Pt and Pt–Re catalysts. The values of the reaction rates and reaction orders predicted by the model are in agreement with the ones experimentally determined; the calculated apparent activation energies are matched to within 6% of the experimental values. The primary reaction pathway is predicted to take place through adsorbed carboxyl (COOH) species, whereas formate (HCOO) is predicted to be a spectator species. We conclude that the clean Pt(111) is a good representation of the active site for the WGS reaction on Pt catalysts, whereas the active sites on the Pt–Re alloy catalyst likely contain partially oxidized metal ensembles.

  9. Monte-Carlo analysis of rarefied-gas diffusion including variance reduction using the theory of Markov random walks

    NASA Technical Reports Server (NTRS)

    Perlmutter, M.

    1973-01-01

    Molecular diffusion through a rarefied gas is analyzed by using the theory of Markov random walks. The Markov walk is simulated on the computer by using random numbers to find the new states from the appropriate transition probabilities. As the sample molecule during its random walk passes a scoring position, which is a location at which the macroscopic diffusing flow variables such as molecular flux and molecular density are desired, an appropriate payoff is scored. The payoff is a function of the sample molecule velocity. For example, in obtaining the molecular flux across a scoring position, the random walk payoff is the net number of times the scoring position has been crossed in the positive direction. Similarly, when the molecular density is required, the payoff is the sum of the inverse velocity of the sample molecule passing the scoring position. The macroscopic diffusing flow variables are then found from the expected payoff of the random walks.

  10. Reciprocating flow-based centrifugal microfluidics mixer

    NASA Astrophysics Data System (ADS)

    Noroozi, Zahra; Kido, Horacio; Micic, Miodrag; Pan, Hansheng; Bartolome, Christian; Princevac, Marko; Zoval, Jim; Madou, Marc

    2009-07-01

    Proper mixing of reagents is of paramount importance for an efficient chemical reaction. While on a large scale there are many good solutions for quantitative mixing of reagents, as of today, efficient and inexpensive fluid mixing in the nanoliter and microliter volume range is still a challenge. Complete, i.e., quantitative mixing is of special importance in any small-scale analytical application because the scarcity of analytes and the low volume of the reagents demand efficient utilization of all available reaction components. In this paper we demonstrate the design and fabrication of a novel centrifugal force-based unit for fast mixing of fluids in the nanoliter to microliter volume range. The device consists of a number of chambers (including two loading chambers, one pressure chamber, and one mixing chamber) that are connected through a network of microchannels, and is made by bonding a slab of polydimethylsiloxane (PDMS) to a glass slide. The PDMS slab was cast using a SU-8 master mold fabricated by a two-level photolithography process. This microfluidic mixer exploits centrifugal force and pneumatic pressure to reciprocate the flow of fluid samples in order to minimize the amount of sample and the time of mixing. The process of mixing was monitored by utilizing the planar laser induced fluorescence (PLIF) technique. A time series of high resolution images of the mixing chamber were analyzed for the spatial distribution of light intensities as the two fluids (suspension of red fluorescent particles and water) mixed. Histograms of the fluorescent emissions within the mixing chamber during different stages of the mixing process were created to quantify the level of mixing of the mixing fluids. The results suggest that quantitative mixing was achieved in less than 3 min. This device can be employed as a stand alone mixing unit or may be integrated into a disk-based microfluidic system where, in addition to mixing, several other sample preparation steps may be included.

  11. Multiphase flow modeling in centrifugal partition chromatography.

    PubMed

    Adelmann, S; Schwienheer, C; Schembecker, G

    2011-09-01

    The separation efficiency in Centrifugal Partition Chromatography (CPC) depends on selection of a suitable biphasic solvent system (distribution ratio, selectivity factor, sample solubility) and is influenced by hydrodynamics in the chambers. Especially the stationary phase retention, the interfacial area for mass transfer and the flow pattern (backmixing) are important parameters. Their relationship with physical properties, operating parameters and chamber geometry is not completely understood and predictions are hardly possible. Experimental flow visualization is expensive and two-dimensional only. Therefore we simulated the flow pattern using a volume-of-fluid (VOF) method, which was implemented in OpenFOAM®. For the three-dimensional simulation of a rotating FCPC®-chamber, gravitational centrifugal and Coriolis forces were added to the conservation equation. For experimental validation the flow pattern of different solvent systems was visualized with an optical measurement system. The amount of mobile phase in a chamber was calculated from gray scale values of videos recorded by an image processing routine in ImageJ®. To visualize the flow of the stationary phase polyethylene particles were used to perform a qualitative particle image velocimetry (PIV) analysis. We found a good agreement between flow patterns and velocity profiles of experiments and simulations. By using the model we found that increasing the chamber depth leads to higher specific interfacial area. Additionally a circular flow in the stationary phase was identified that lowers the interfacial area because it pushes the jet of mobile phase to the chamber wall. The Coriolis force alone gives the impulse for this behavior. As a result the model is easier to handle than experiments and allows 3D prediction of hydrodynamics in the chamber. Additionally it can be used for optimizing geometry and operating parameters for given physical properties of solvent systems. PMID:21324465

  12. Dynamic mean field theory for lattice gas models of fluid mixtures confined in mesoporous materials.

    PubMed

    Edison, J R; Monson, P A

    2013-11-12

    We present the extension of dynamic mean field theory (DMFT) for fluids in porous materials (Monson, P. A. J. Chem. Phys. 2008, 128, 084701) to the case of mixtures. The theory can be used to describe the relaxation processes in the approach to equilibrium or metastable equilibrium states for fluids in pores after a change in the bulk pressure or composition. It is especially useful for studying systems where there are capillary condensation or evaporation transitions. Nucleation processes associated with these transitions are emergent features of the theory and can be visualized via the time dependence of the density distribution and composition distribution in the system. For mixtures an important component of the dynamics is relaxation of the composition distribution in the system, especially in the neighborhood of vapor-liquid interfaces. We consider two different types of mixtures, modeling hydrocarbon adsorption in carbon-like slit pores. We first present results on bulk phase equilibria of the mixtures and then the equilibrium (stable/metastable) behavior of these mixtures in a finite slit pore and an inkbottle pore. We then use DMFT to describe the evolution of the density and composition in the pore in the approach to equilibrium after changing the state of the bulk fluid via composition or pressure changes. PMID:24102541

  13. Plasma Centrifuge Heat Engine - a Route to Non-thermal p- 11 B Fusion

    NASA Astrophysics Data System (ADS)

    Barnes, D. C.

    2007-06-01

    An invention [US Patent and Trademark Office App. Nos. 60/596567 (2005) and 60/766791 (2006)] combines centrifugal and dipole confinement, with recent oscillating plasma theory. The plasma undergoes compression/expansion (C/E), parallel to B by centrifugal force and perpendicular to B by B variation, providing a thermal cycle which recovers most (>95%) of heating as mechanical energy. This gives a "Q-amplifier" for beam-target systems. Centrifugally confined Boron plasma undergoes C/E by slow, cross-B interchange activity. Parallel and perpendicular C/E are matched by the rotation profile which arises naturally. Hot plasma is heated and cold plasma is cooled. Beam-target fusion reactions occur in the hot plasma region and expansion returns most of the heat energy as rotation energy. Rotation energy, in turn, produces waves which drive protons to an energy near the fusion peak cross section. A possible machine, including the arrangement of magnets and HV, is described.

  14. On using eco-physiological, micrometeorological and biogeochemical theory to evaluate carbon dioxide, water vapor and trace gas fluxes over vegetation: a perspective

    Microsoft Academic Search

    Dennis Baldocchi; Tilden Meyers

    1998-01-01

    How eco-physiological, biogeochemical and micrometeorological theory can be used to compute biosphere–atmosphere, trace gas exchange rates is discussed within the framework of a process model. The accuracy of the theory is tested by comparing computations of mass and energy flux densities (water vapor, sensible heat, CO2 and ozone) against eddy covariance measurements over five distinct canopies (wheat, potato and soybean

  15. Tropic responses of Phycomyces sporangiophores to gravitational and centrifugal stimuli.

    PubMed

    DENNISON, D S

    1961-09-01

    A low-speed centrifuge was used to study the tropic responses of Phycomyces sporangiophores in darkness to the stimulus of combined gravitational and centrifugal forces. If this stimulus is constant the response is a relatively slow tropic reaction, which persists for up to 12 hours. The response is accelerated by increasing the magnitude of the gravitational-centrifugal force. A wholly different tropic response, the transient response, is elicited by an abrupt change in the gravitational-centrifugal stimulus. The transient response has a duration of only about 6 min. but is characterized by a high bending speed (about 5 degrees /min.). An analysis of the distribution of the transient response along the growing zone shows that the active phase of the response has a distribution similar to that of the light sensitivity for the light-growth and phototropic responses. Experiments in which sporangiophores are centrifuged in an inert dense fluid indicate that the sensory mechanism of the transient response is closely related to the physical deformation of the growing zone caused by the action of the gravitational-centrifugal force on the sporangiophore as a whole. However, the response to a steady gravitational-centrifugal force is most likely not connected with this deformation, but is probably triggered by the shifting of regions or particles of differing density relative to one another inside the cell. PMID:13721903

  16. Tropic Responses of Phycomyces Sporangiophores to Gravitational and Centrifugal Stimuli

    PubMed Central

    Dennison, David S.

    1961-01-01

    A low-speed centrifuge was used to study the tropic responses of Phycomyces sporangiophores in darkness to the stimulus of combined gravitational and centrifugal forces. If this stimulus is constant the response is a relatively slow tropic reaction, which persists for up to 12 hours. The response is accelerated by increasing the magnitude of the gravitational-centrifugal force. A wholly different tropic response, the transient response, is elicited by an abrupt change in the gravitational-centrifugal stimulus. The transient response has a duration of only about 6 min. but is characterized by a high bending speed (about 5°/min.). An analysis of the distribution of the transient response along the growing zone shows that the active phase of the response has a distribution similar to that of the light sensitivity for the light-growth and phototropic responses. Experiments in which sporangiophores are centrifuged in an inert dense fluid indicate that the sensory mechanism of the transient response is closely related to the physical deformation of the growing zone caused by the action of the gravitational-centrifugal force on the sporangiophore as a whole. However, the response to a steady gravitational-centrifugal force is most likely not connected with this deformation, but is probably triggered by the shifting of regions or particles of differing density relative to one another inside the cell. PMID:13721903

  17. Centrifugal Casting Features/Metallurgical Characterization of Aluminum Alloys

    NASA Astrophysics Data System (ADS)

    Chirita, G.; Stefanescu, I.; Soares, D.; Cruz, D.; Silva, F. S.

    2008-02-01

    This paper deals with the study of centrifugal effects on aluminium castings under high G values. Most of the studies in this domain (FGMs obtained by centrifugal casting) deal with functionally graded composites reinforced with a solid phase such as silicon particles or others. However, in this study it will be shown that unreinforced aluminium alloys may be significantly influenced by the centrifugal effect and that functionally graded castings are also obtained. It has been observed that the centrifugal effect may increase in some alloys, depending on the relative position in the castings, the rupture strength by approx. 50%, and rupture strain by about 300%, as compared to the gravity casting technique. The Young's modulus may also increase by about 20%. It has also been reported that in vertical centrifugal castings there are mainly three aspects that affect the components thus obtained, namely: fluid dynamics; vibration (inherent to the system); and centrifugal force. These features have a different effect on the castings depending on the aluminium alloy. In this paper, an analysis of the most important effects of the centrifugal casting process on metallurgical features is conducted. A solidification characterization at several points along the mould will be made in order to have an accurate idea of both the fluid dynamics inside the mould during the casting and the solidification behavior in different parts of the component. These two analyses will be related to the metallurgical properties (phase distribution; SDAS; eutectic silicon content and shape, pores density and shape) along the component and mainly along the direction of the centrifugal pressure. A comparison between castings obtained by both centrifugal casting technique and gravity casting technique is made for reference (gravity casting).

  18. Centrifugal Casting Features/Metallurgical Characterization of Aluminum Alloys

    SciTech Connect

    Chirita, G.; Soares, D.; Cruz, D.; Silva, F. S. [Mechanical Engineering Department, School of Engineering, Minho University (Portugal); Stefanescu, I. [Faculty of Mechanical Engineering, Dunarea de Jos University Galati (Romania)

    2008-02-15

    This paper deals with the study of centrifugal effects on aluminium castings under high G values. Most of the studies in this domain (FGMs obtained by centrifugal casting) deal with functionally graded composites reinforced with a solid phase such as silicon particles or others. However, in this study it will be shown that unreinforced aluminium alloys may be significantly influenced by the centrifugal effect and that functionally graded castings are also obtained. It has been observed that the centrifugal effect may increase in some alloys, depending on the relative position in the castings, the rupture strength by approx. 50%, and rupture strain by about 300%, as compared to the gravity casting technique. The Young's modulus may also increase by about 20%. It has also been reported that in vertical centrifugal castings there are mainly three aspects that affect the components thus obtained, namely: fluid dynamics; vibration (inherent to the system); and centrifugal force. These features have a different effect on the castings depending on the aluminium alloy. In this paper, an analysis of the most important effects of the centrifugal casting process on metallurgical features is conducted. A solidification characterization at several points along the mould will be made in order to have an accurate idea of both the fluid dynamics inside the mould during the casting and the solidification behavior in different parts of the component. These two analyses will be related to the metallurgical properties (phase distribution; SDAS; eutectic silicon content and shape, pores density and shape) along the component and mainly along the direction of the centrifugal pressure. A comparison between castings obtained by both centrifugal casting technique and gravity casting technique is made for reference (gravity casting)

  19. Effects of centrifugal drift on hurricane structure and intensity

    NASA Astrophysics Data System (ADS)

    Tripoli, G. J.; Hashino, T.; Lewis, W.

    2009-04-01

    High (1km) resolution simulations of the 2005 hurricane Wilma were conducted using the UW-NMS which models the effect of horizontal precipitation drift due to centrifugal force. The extremely tight nature of Wilma's vortex suggests that there should be a measurable horizontal drift of precipitation, comparable to the vertical motion, that is due to centrifugal terminal velocity. These effects would likely unload the updraft in the central core of the storm. Explicit calculations of this effect will be presented at the oral presentation and implications of centrifugal horizontal drift to the general 3D structure of a tropical cyclone will be discussed.

  20. Ocular counterrolling induced by centrifugation during orbital space flight

    NASA Technical Reports Server (NTRS)

    Moore, S. T.; Clement, G.; Raphan, T.; Cohen, B.

    2001-01-01

    During the 1998 Neurolab mission (STS-90), four astronauts were exposed to interaural centripetal accelerations (Gy centrifugation) of 0.5 g and 1 g during rotation on a centrifuge, both on Earth and during orbital space flight. Subjects were oriented either left-ear out or right-ear out, facing or back to motion. Binocular eye movements were measured in three dimensions using a video technique. On Earth, tangential centrifugation that produces 1 g of interaural linear acceleration combines with gravity to tilt the gravitoinertial acceleration (GIA) vector 45 degrees in the roll plane relative to the head vertical, generating a summed vector of 1.4 g. Before flight, this elicited mean ocular counterrolling (OCR) of 5.7 degrees. Due to the relative absence of gravity during flight, there was no linear acceleration along the dorsoventral axis of the head. As a result, during in-flight centrifugation, gravitoinertial acceleration was strictly aligned with the centripetal acceleration along the interaural axis. There was a small but significant decrease (mean 10%) in the magnitude of OCR in space (5.1 degrees). The magnitude of OCR during postflight 1 g centrifugation was not significantly different from preflight OCR (5.9 degrees). Findings were similar for 0.5 g centrifugation, but the OCR magnitude was approximately 60% of that induced by centrifugation at 1 g. OCR during pre- and postflight static tilt was not significantly different and was always less than OCR elicited by centrifugation of Earth for an equivalent interaural linear acceleration. In contrast, there was no difference between the OCR generated by in-flight centrifugation and by static tilt on Earth at equivalent interaural linear accelerations. These data support the following conclusions: (1) OCR is generated predominantly in response to interaural linear acceleration; (2) the increased OCR during centrifugation on Earth is a response to the head dorsoventral 1 g linear acceleration component, which was absent in microgravity. The dorsoventral linear acceleration could have activated either the otoliths or body-tilt receptors that responded to the larger GIA magnitude (1.4 g), to generate the increased OCR during centrifugation on Earth. A striking finding was that magnitude of OCR was maintained throughout and after flight. This is in contrast to most previous postflight OCR studies, which have generally registered decreases in OCR. We postulate that intermittent exposure to artificial gravity, in the form of the centripetal acceleration experienced during centrifugation, acted as a countermeasure to deconditioning of this otolith-ocular orienting reflex during the 16-day mission.

  1. Efficiency calculation and the vortex characteristics research of centrifugal pump

    NASA Astrophysics Data System (ADS)

    Ge, X. F.; Gao, Z. X.; Zheng, Y.; Shen, M. H.

    2012-11-01

    Efficiency is an important performance indicator of the centrifugal pump, this paper establish three-dimensional model of one high head centrifugal pump in domestic with CFD software, though changing the operating conditions, statistics the calculation efficiency and energy loss under different operating conditions, compare the impact to efficiency and head calculation with steady and unsteady calculation methods, and research the affect when runner in different locations in the centrifugal pump, given and analysis the reasons of the flow field and pressure distribution of runner in different steps.

  2. Research on 3-D discharge flow in a centrifugal impeller

    NASA Astrophysics Data System (ADS)

    Xi, Guang; Wang, Shangjin

    1993-01-01

    A method for calculating 3D discharge flow in a centrifugal impeller is developed by means of solving the incompressible steady time-averaged N-S equations, the continuity equation, and the k-epsilon turbulence model equation. This method is accomplished with calculation grids generated by an algebraic transformation, and thus it can be easily applied to the design analysis of centrifugal impellers. The discharge flow of a three-dimensional shrouded centrifugal compressor impeller was measured for assessing the validity of the present calculation procedure. The comparison between the experimental data and the calculation results shows that the present method can predict the mean velocities.

  3. Adjustable Speed Drives as Applied to Centrifugal Pumps 

    E-print Network

    Jarc, D. A.; Robechek, J. D.; Connors, D. P.

    1982-01-01

    ADJUSTABLE SPEED DRIVES AS APPLIED TO CENTRIFUGAL PUMPS Dennis P. Connors, John D. Robechek, and Dennis A. Jarc Reliance Electric Company Cleveland, Ohio 100 100 100 8080 80 6060 60 0: W ~ 40 0: w 40 40 0 c.. ::::> en I- en... i= 6 ~ 5 ~ 4 o oJ 3 ~ 2 ~ 1 ?I I. I *- 0 10 20 30 40 50 60 70 80 90 100 % flOW FIGURE 3 Typical Centrifugal Pump Duty Cycle LrJ Pump Curve a: iil A w '" a: l>. a: o o Centrifugal Pump Curve...

  4. Application of Momentum Transfer Theory for Ion and Electron Transport in Pure Gases and in Gas Mixtures

    NASA Astrophysics Data System (ADS)

    Jovanovi?, J. V.; Vrhovac, S. B.

    2004-12-01

    In this paper we have presented two applications of Momentum Transfer Theory (MTT), which were both aimed at obtaining reliable data for modeling of non-equilibrium plasma. Transport properties of ion swarms in presence of Resonant Charge Transfer (RCT) collisions are studied using Momentum Transfer Theory (MTT). Using the developed MTT we tested a previously available anisotropic set of cross-sections for Ar++Ar collisions bay making the comparisons with the available data for the transverse diffusion coefficient. We also developed an anisotropic set of Ne++Ne integral cross-sections based on the available data for mobility, longitudinal and transverse diffusion. Anisotropic sets of cross-sections are needed for Monte Carlo simulations of ion transport and plasma models. Application of Blanc's Law for drift velocities of electrons and ions in gas mixtures at arbitrary reduced electric field strenghts E/n0 was studied theoretically and by numerical examples. Corrections for Blanc's Law that include effects of inelastic collisions were derived. In addition we have derived the common mean energy procedure that was proposed by Chiflikian in a general case both for ions and electrons. Both corrected common E/n0 and common mean energy procedures provide excellent results even for electrons at moderate E/n0 where application of Blanc's Law was regarded as impossible. In mixtures of two gases that have negative differential conductivity (NDC) even when neither of the two pure gases show NDC the Blanc's Law procedure was able to give excellent predictions.

  5. Some theories of dissolved gas release from Tank 241-SY-101

    SciTech Connect

    Allemann, R.T.

    1994-09-01

    This report explains the ammonia release data to an order of magnitude agreement by the combination of three mechanisms of release: (1) bubble transport, (2) permeation/diffusion through the upper layers of the waste, and (3) diffusion/evaporation from freshly exposed liquid surfaces. Bounded by these mechanisms, there is low danger of extremely high ammonia concentrations in the off gas. This condition would occur through some (unlikely) continuous replenishing of fresh liquid on the surface. This would not occur unless there were continuous energetic rollovers, which seem very unlikely given historical evidence, or by energetic mixing of the waste with more power than provided by the current mixing pump. Nitrous oxide is of low solubility in the waste and behaves similarly to hydrogen.

  6. Resolving rainbows with superimposed diffraction oscillations in NO + rare gas scattering: experiment and theory

    NASA Astrophysics Data System (ADS)

    Onvlee, Jolijn; Vogels, Sjoerd N.; van der Avoird, Ad; Groenenboom, Gerrit C.; van de Meerakker, Sebastiaan Y. T.

    2015-05-01

    A Stark decelerator is used in combination with velocity map imaging to study collisions of NO radicals with rare gas atoms in a counterpropagating crossed beam geometry. This powerful combination of techniques results in scattering images with extremely high resolution, in which rotational and L-type rainbows with superimposed quantum mechanical diffraction oscillations are visible. The experimental data are in excellent agreement with quantum mechanical scattering calculations. Furthermore, hard-shell models and a partial wave analysis are used to clarify the origin of the various structures that are visible. A specific feature is found for NO molecules colliding with Ar atoms that is extremely sensitive to the precise shape of the potential energy surface. Its origin is explained in terms of interfering partial waves with very high angular momentum, corresponding to trajectories with large impact parameters.

  7. Characterization of flow intensity in continuous centrifuges for the development of laboratory mimics

    Microsoft Academic Search

    M Boychyn; S. S. S Yim; P Ayazi Shamlou; M Bulmer; J More; M Hoare

    2001-01-01

    Predicting the recovery of “delicate” biological materials by centrifugation using laboratory centrifuges has been a major challenge to biochemical engineers partly because of the difficulty in accurately quantifying the shear stresses in continuous-flow industrial centrifuges and partly because the clarification and dewatering conditions in the laboratory units do not represent those occurring in industrial centrifuges. In this paper, the flow

  8. The magnetic centrifugal mass filter Abraham J. Fetterman and Nathaniel J. Fisch

    E-print Network

    The magnetic centrifugal mass filter Abraham J. Fetterman and Nathaniel J. Fisch Department centrifugal and magnetic confinement of ions in a way similar to the asymmetric centrifugal trap. This magnetic centrifugal mass filter is shown to be more proliferation resistant than present technology

  9. THE SEPARATION OF CRAB MEAT FROM SHELL & TENDON BY A CENTRIFUGAL PROCESS

    E-print Network

    THE SEPARATION OF CRAB MEAT FROM SHELL & TENDON BY A CENTRIFUGAL PROCESS Wayne I. Tretsven of centrifugal force tothe problem. Trials with an industrial, solid -bowl centrifuge indicated that a machine of this type had great potential for the separation of meat from shell. The centrifuge, a Bird Machine Co

  10. Semiclassical theory of alignment effects in near-resonant energy-transfer collisions of rare-gas atoms with aligned Rydberg atoms

    E-print Network

    Morrison, Michael A.

    Semiclassical theory of alignment effects in near-resonant energy-transfer collisions of rare-gas atoms with aligned Rydberg atoms Eric G. Layton Joint Institute for Laboratory Astrophysics, University experiments E. M. Spain et al., J. Chem. Phys 102, 24 1995 discovered alignment effects in cross sections

  11. CHEMISTRY 223: Introductory Physical Chemistry I. Kinetics 1: Gas laws, kinetic theory of collisions. Thermodynamics: Zeroth law of thermodynamics. First law of thermodynamics, heat capacity,

    E-print Network

    Ronis, David M.

    CHEMISTRY 223: Introductory Physical Chemistry I. Kinetics 1: Gas laws, kinetic theory edition (Pearson Education, Inc., 2013). J.R. Barrante, Applied Mathematics for Physical Chemistry, 3rd edition (Pearson Education, Inc., 2004). Supplementary Texts 1. G. W. Castellan, Physical Chemistry 3rd

  12. Investigation of the jet-wake flow of a highly loaded centrifugal compressor impeller

    NASA Technical Reports Server (NTRS)

    Eckardt, D.

    1978-01-01

    Investigations, aimed at developing a better understanding of the complex flow field in high performance centrifugal compressors were performed. Newly developed measuring techniques for unsteady static and total pressures as well as flow directions, and a digital data analysis system for fluctuating signals were thoroughly tested. The loss-affected mixing process of the distorted impeller discharge flow was investigated in detail, in the absolute and relative system, at impeller tip speeds up to 380 m/s. A theoretical analysis proved good coincidence of the test results with the DEAN-SENOO theory, which was extended to compressible flows.

  13. 3. Interior view of centrifugal pump house showing pumps and ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    3. Interior view of centrifugal pump house showing pumps and engines, looking W. - Laurel Valley Sugar Plantation, Drainage Plant, 2 Miles South of Thibodaux on State Route 308, Thibodaux, Lafourche Parish, LA

  14. Manufacture of hollow ingots using centrifugal casting machines

    NASA Astrophysics Data System (ADS)

    Pomeshchikov, A. G.; Greneva, T. S.; Baidachenko, V. I.; Berezin, V. I.

    2010-12-01

    Centrifugal machines are proposed for the foundry created at the Almalyk Mining and Smelting Factory in order to produce hollow ingots of a liquid metal made by remelting of consumable electrodes in a refractory accumulating crucible.

  15. 8. FLOOR 1: TENTERING GEAR FOR SOUTH STONES, CENTRIFUGAL GOVERNOR ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    8. FLOOR 1: TENTERING GEAR FOR SOUTH STONES, CENTRIFUGAL GOVERNOR MOUNTED ON STONE SPINDLE, VERY SHORT STEELYARD - Windmill at Water Mill, Montauk Highway & Halsey Lane, Water Mill, Suffolk County, NY

  16. Characterization of unsteady flow processes in a centrifugal compressor stage

    E-print Network

    Gould, Kenneth A. (Kenneth Arthur)

    2006-01-01

    Numerical experiments have been implemented to characterize the unsteady loading on the rotating impeller blades in a modem centrifugal compressor. These consist of unsteady Reynolds-averaged Navier Stokes simulations of ...

  17. 23. TEMPORARY CENTRIFUGAL PUMP. NOTE CHAPMAN HYDRAULICOPERATED VALVE FOR LATER ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    23. TEMPORARY CENTRIFUGAL PUMP. NOTE CHAPMAN HYDRAULIC-OPERATED VALVE FOR LATER CONNECTION OF ENGINE PUMP ENG TO DISCHARGE HEADER. - Lakeview Pumping Station, Clarendon & Montrose Avenues, Chicago, Cook County, IL

  18. Cross plane transfer of vestibular adaptation to human centrifugation

    E-print Network

    Garrick-Bethell, Ian, 1980-

    2004-01-01

    Human short-radius centrifugation (SRC) is being investigated as a volume-efficient means of delivering intermittent doses of "artificial gravity" to counter the deleterious effects of long exposures to weightlessness. ...

  19. Ballistic to centrifuging flow of granular materials in rotating tumblers

    NASA Astrophysics Data System (ADS)

    Lueptow, Richard M.; Juarez, Gabriel; Chen, Pengfei; Ottino, Julio M.

    2009-11-01

    The critical rotation speed for centrifuging of granular materials in horizontal rotating tumblers, determined by the Froude number, was studied experimentally and computationally as a function of the particle diameter, tumbler fill fraction, interstitial fluid, and tumbler length. Particle size does not affect the critical speed for centrifugation provided that the fill fraction is below 50%. The actual critical speed is typically 1.4 times the theoretical speed for centrifugation. Above 50% fill, the critical speed increases with particle size. Simulations indicate that even for the centrifuging condition there is relative motion of particles due to gravity, especially near the free surface. The presence of an interstitial fluid alters the critical speed due to buoyancy.

  20. Return channel loss reduction in multi-stage centrifugal compressors

    E-print Network

    Aubry, Anne-Raphaëlle

    2012-01-01

    This thesis presents concepts for improving the performance of return channels in multi-stage centrifugal compressors. Geometries have been developed to reduce both separation and viscous losses. A number of different ...