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Sample records for gas centrifuge theory

  1. 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.

  2. Centrifugal Gas Compression Cycle

    NASA Astrophysics Data System (ADS)

    Fultun, Roy

    2002-11-01

    A centrifuged gas of kinetic, elastic hard spheres compresses isothermally and without flow of heat in a process that reverses free expansion. This theorem follows from stated assumptions via a collection of thought experiments, theorems and other supporting results, and it excludes application of the reversible mechanical adiabatic power law in this context. The existence of an isothermal adiabatic centrifugal compression process makes a three-process cycle possible using a fixed sample of the working gas. The three processes are: adiabatic mechanical expansion and cooling against a piston, isothermal adiabatic centrifugal compression back to the original volume, and isochoric temperature rise back to the original temperature due to an influx of heat. This cycle forms the basis for a Thomson perpetuum mobile that induces a loop of energy flow in an isolated system consisting of a heat bath connectable by a thermal path to the working gas, a mechanical extractor of the gas's internal energy, and a device that uses that mechanical energy and dissipates it as heat back into the heat bath. We present a simple experimental procedure to test the assertion that adiabatic centrifugal compression is isothermal. An energy budget for the cycle provides a criterion for breakeven in the conversion of heat to mechanical energy.

  3. 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.

  4. Laser and gas centrifuge enrichment

    SciTech Connect

    Heinonen, Olli

    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.

  5. Gas dynamics in strong centrifugal fields

    SciTech Connect

    Bogovalov, S.V.; Kislov, V.A.; Tronin, I.V.

    2015-03-10

    Dynamics of waves generated by scopes in gas centrifuges (GC) for isotope separation is considered. The centrifugal acceleration in the GC reaches values of the order of 106g. The centrifugal and Coriolis forces modify essentially the conventional sound waves. Three families of the waves with different polarisation and dispersion exist in these conditions. Dynamics of the flow in the model GC Iguasu is investigated numerically. Comparison of the results of the numerical modelling of the wave dynamics with the analytical predictions is performed. New phenomena of the resonances in the GC is found. The resonances occur for the waves polarized along the rotational axis having the smallest dumping due to the viscosity.

  6. Waves in strong centrifugal fields: dissipationless gas

    NASA Astrophysics Data System (ADS)

    Bogovalov, S. V.; Kislov, V. A.; Tronin, I. V.

    2015-04-01

    Linear waves are investigated in a rotating gas under the condition of strong centrifugal acceleration of the order 106 g realized in gas centrifuges for separation of uranium isotopes. Sound waves split into three families of the waves under these conditions. Dispersion equations are obtained. The characteristics of the waves strongly differ from the conventional sound waves on polarization, velocity of propagation and distribution of energy of the waves in space for two families having frequencies above and below the frequency of the conventional sound waves. The energy of these waves is localized in rarefied region of the gas. The waves of the third family were not specified before. They propagate exactly along the rotational axis with the conventional sound velocity. These waves are polarized only along the rotational axis. Radial and azimuthal motions are not excited. Energy of the waves is concentrated near the wall of the rotor where the density of the gas is largest.

  7. 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)

  8. 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.

  9. 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.

    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.

  10. 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.

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

    SciTech Connect

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

    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.

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

    SciTech Connect

    Boyer, Brian David; Erpenbeck, Heather H; Miller, Karen A; Swinhoe, Martyn T; Ianakiev, Kiril; Marlow, Johnna B

    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.

  13. 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

    ,” (Shaeffer 2013). MEMS have been used both in the field and the laboratory by geotechnical engineers. In brief, examples include: measuring wave propagation with custom packaged MEMS accelerometer chips and/or circuits (Hoffman et al. 2006... , in brief, examples include: evaluation of MEMS accelerometers in dynamic centrifuge testing (Stringer et al. 2010), seismic evaluation of pile reinforced slopes (Al-Defae and Knappett 2014), and measurement of pile rotation (Lau et al. 2014). However...

  14. Application of energy gradient theory in flow instability in a centrifugal pump

    NASA Astrophysics Data System (ADS)

    Dou, H. S.; Jiang, W.

    2013-12-01

    The flow instability in a centrifugal pump is studied using the energy gradient theory. Since the Re is high, the base flow is assumed to be turbulent. The distribution of the energy gradient function K at various flow rates is obtained from numerical simulations. According to the energy gradient method, the area with larger value of K is the place to cause instability and to be of high turbulence intensity. The results show that instability is easier to be excited in the area of impeller outlet and volute tongue. In order to improve the stability of centrifugal pumps working under low flow rate condition, carefulness must be taken in these two key areas.

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

    SciTech Connect

    Dongjun Jiang; Shi Zeng

    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. Development Of A Centrifugal Hydrogen Pipeline Gas Compressor

    SciTech Connect

    Di Bella, Francis A.

    2015-04-16

    Concepts NREC (CN) has completed a Department of Energy (DOE) sponsored project to analyze, design, and fabricate a pipeline capacity hydrogen compressor. The pipeline compressor is a critical component in the DOE strategy to provide sufficient quantities of hydrogen to support the expected shift in transportation fuels from liquid and natural gas to hydrogen. The hydrogen would be generated by renewable energy (solar, wind, and perhaps even tidal or ocean), and would be electrolyzed from water. The hydrogen would then be transported to the population centers in the U.S., where fuel-cell vehicles are expected to become popular and necessary to relieve dependency on fossil fuels. The specifications for the required pipeline hydrogen compressor indicates a need for a small package that is efficient, less costly, and more reliable than what is available in the form of a multi-cylinder, reciprocating (positive displacement) compressor for compressing hydrogen in the gas industry.

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

    SciTech Connect

    Swindle, D.W.

    1990-03-01

    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 plants. This effort, known as the Hexapartite Safeguards Project (HSP), led to the first international concensus on techniques and requirements for effective verification of the absence of weapons-grade nuclear materials production. Since that agreement, research and development has continued on the radiation detection technology-based technique that technically confirms the HSP goal is achievable. However, the realities of achieving the HSP goal of effective technical verification have not yet been fully attained. Issues such as design and operating conditions unique to each gas centrifuge plant, concern about the potential for sensitive technology disclosures, and on-site support requirements have hindered full implementation and operator support of the HSP agreement. In future arms control treaties that may limit or monitor fissile material production, the negotiators must recognize and account for the realities and practicalities in verifying the absence of HEU production. This paper will describe the experiences and realities of trying to achieve the goal of developing and implementing an effective approach for verifying the absence of HEU production. 3 figs.

  18. 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.

  19. Microcomputer-based instrument for the detection and analysis of precession motion in a gas centrifuge machine. Revision 1

    SciTech Connect

    Paulus, S.S.

    1986-03-01

    The Centrifuge Procession Analyzer (CPA) is a microcomputer-based instrument which detects precession motion in a gas centrifuge machine and calculates the amplitude and frequency of precession. The CPA consists of a printed circuit board which contains signal-conditioning circuitry and a 24-bit counter and an INTEL iSBC 80/24 single/board computer. Pression motion is detected by monitoring a signal generated by a variable reluctance pick-up coil in the top of the centrifuge machine. This signal is called a Fidler signal. The initial Fidler signal triggers a counter which is clocked by a high-precision, 20.000000-MHz, temperature-controlled, crystal oscillator. The contents of the counter are read by the computer and the counter reset after every ten Fidler signals. The speed of the centrifuge machine and the amplitude and frequency of precession are calculated and the results are displayed on a liquid crystal display on the front panel of the CPA. The report contains results from data generated by a Fidler signal simulator and data taken when the centrifuge was operated under three test conditions: (1) nitrogen gas during drive-up, steady state, and drive-down; (2) xenon gas during slip test, steady state, and the addition of gas; and (3) no gas during steady state. The qualitative results were consistent with experience with centrifuge machines using UF/sub 6/ in that the amplitude of precession increased and the frequency of precession decreased during drive-up, drive-down and the slip check. The magnitude of the amplitude and frequency of precession were proportional to the molecular weight of the gases in steady state.

  20. Microcomputer-based instrument for the detection and analysis of precession motion in a gas centrifuge machine

    SciTech Connect

    Paulus, S.S.

    1986-03-01

    The Centrifuge Precession Analyzer (CPA) is a microcomputer-based instrument which detects precession motion in a gas centrifuge machine and calculates the amplitude and frequency of precession. The CPA consists of a printed circuit board which contains signal-conditioning circuitry and a 24-bit counter and an INTEL iSBC 80-/24 single-board computer. Precession motion is detected by monitoring a signal generated by a variable reluctance pick-up coil in the top of the centrifuge machine. This signal is called a Fidler signal. The initial Fidler signal triggers a counter which is clocked by a high-precision, 20.000000-MHz, temperature-controlled, crystal oscillator. The contents of the counter are read by the computer, and the counter reset after every ten Fidler signals. The speed of the centrifuge machine and the amplitude and frequency of precession are calculated, and the results are displayed on a liquid crystal display on the front panel of the CPA. The thesis contains results from data generated by a Fidler signal simulator and data taken when the centrifuge was operated under three test conditions: (1) nitrogen gas during drive-up, steady state, and drive-down, (2) xenon gas during slip test, steady state, and the addition of gas, and (3) no gas during steady state. The qualitative results were consistent with experience with centrifuge machines UF/sub 6/ in that the amplitude of precession increased and the frequency of precession decreased during drive-up, drive-down and the slip check. The magnitude of the amplitude and frequency of precession were proportional to the molecular weight of the gases in steady state.

  1. 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.

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

    SciTech Connect

    Garner, James R; Whitaker, J Michael

    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.

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

    SciTech Connect

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

    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.

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

    SciTech Connect

    Boyer, Brian David; Erpenbeck, Heather H; Miller, Karen A; Ianakiev, Kiril D; Reimold, Benjamin A; Ward, Steven L; Howell, John

    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.

  5. 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.

  6. 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

    ... and having a specific modulus of 3.18 × 106 m or greater and a specific ultimate tensile strength of 7... weight in N/m 3 when measured at a temperature of 23±20C and a relative humidity of 50±5%. “Specific... gas centrifuge normally consists of a thin-walled cylinder(s) of between 75mm (3 ins.) and 400 mm...

  7. 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

    ... and having a specific modulus of 3.18 × 106 m or greater and a specific ultimate tensile strength of 7... weight in N/m 3 when measured at a temperature of 23±20C and a relative humidity of 50±5%. “Specific... gas centrifuge normally consists of a thin-walled cylinder(s) of between 75mm (3 ins.) and 400 mm...

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

    SciTech Connect

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

    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.

  9. 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.

  10. 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.

  11. Corrosion evaluation of cooling-water treatments for gas centrifuge facilities

    SciTech Connect

    Schmidt, C. R.; Meredith, P. F.

    1980-11-24

    The corrosion resistance of six different types of weighted metal coupons was evaluated at 29/sup 0/C (84/sup 0/F) in flowing water containing nitrite-borate-silicate corrosion inhibitors. The question for evaluation was whether it would be more advantageous: (1) to drain the treated cooling water from the centrifuge machine and to expose them to moisture-laden air over an assumed shop downtime and repair perid of 1 month; or (2) to let the treated cooling water remain stagnant in the machines during this downtime. The moisture-laden-air exposure was more detrimental.

  12. Validation of high-resolution gamma-ray computed tomography for quantitative gas holdup measurements in centrifugal pumps

    NASA Astrophysics Data System (ADS)

    Bieberle, André; Schäfer, Thomas; Neumann, Martin; Hampel, Uwe

    2015-09-01

    In this article, the capability of high-resolution gamma-ray computed tomography (HireCT) for quantitative gas-liquid phase distribution measurements in commercially available industrial pumps is experimentally investigated. The object of interest thereby operates under two-phase flow conditions. HireCT System comprises a collimated 137Cs isotopic source, a radiation detector arc with a multi-channel signal processing unit, and a rotary unit enabling CT scans of objects with diameters of up to 700?mm. The accuracy of gas holdup measurements was validated on a sophisticated modular test mockup replicating defined gas-liquid distributions, which are expected in impeller chambers of industrial centrifugal pumps under two-phase operation. Stationary as well as rotation-synchronized CT scanning techniques have been analyzed, which are both used to obtain sharply resolved gas phase distributions in rotating structures as well as non-rotating zones. A measuring accuracy of better than 1% absolute for variously distributed static gas holdups in the rotating frame has been verified with the modular test mockup using HireCT.

  13. Centrifugal bubble O{sub 2} ({sup 1{Delta}}) gas generator with a total pressure of 100 Torr

    SciTech Connect

    Zagidulin, M V; Nikolaev, V D; Svistun, M I; Khvatov, N A

    2008-08-31

    A centrifugal bubbling singlet-oxygen gas generator is developed in which chlorine with helium are injected into the rotating layer of the alkali solution of hydrogen peroxide through cylindrical nozzles directed at an angle of 30{sup 0} to the bubbler surface. The concentrations of water vapour and O{sub 2} ({sup 1{Delta}}) and the gas temperature were determined by using the multichannel recording of the emission bands of oxygen at 634, 703, 762 and 1268 nm. For the chlorine and helium flow rates of 60 and 90 mmol s{sup -1}, respectively, the specific chlorine load of 3.2 mmol cm{sup -2}, a total pressure of 100 Torr in the working region of the gas generator and the oxygen partial pressure of 36 Torr, the chlorine utilisation was 90% and the content of O{sub 2} ({sup 1{Delta}}) was {approx}60%. For the ratio of the flow rates of chlorine and the alkali solution of hydrogen peroxide equal to 1 mol L{sup -1}, the water vapour content was {approx}25%. The chemical efficiency of the oxygen-iodine laser with this gas generator achieved 23% for the specific power of 12.7 W cm per 1 cm{sup 3} s{sup -1} per pass of the solution through the gas generator. (laser applications and other topics in quantum electronics)

  14. 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.

  15. 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.

  16. Theory of finite disturbances in a centrifugal compression system with a vaneless radial diffuser

    NASA Technical Reports Server (NTRS)

    Moore, F. K.

    1990-01-01

    A previous small perturbation analysis of circumferential waves in circumferential compression systems, assuming inviscid flow, is shown to be consistent with observations that narrow diffusers are more stable than wide ones, when boundary layer displacement effect is included. The Moore-Greitzer analysis for finite strength transients containing both surge and rotating stall in axial machines is adapted for a centrifugal compression system. Under certain assumptions, and except for a new second order swirl, the diffuser velocity field, including resonant singularities, can be carried over from the previous inviscid linear analysis. Nonlinear transient equations are derived and applied in a simple example to show that throttling through a resonant value of flow coefficient must occur in a sudden surge-like drop, accompanied by a transient rotating wave. This inner solution is superseded by an outer surge response on a longer time scale. Surge may occur purely as result of circumferential wave resonance. Numerical results are shown for various parametric choices relating to throttle schedule and the characteristic slope. A number of circumferential modes considered simultaneously is briefly discussed.

  17. Centrifugal main fuel pump

    SciTech Connect

    Cole, E.F.

    1986-08-26

    For a gas turbine power plant having a fuel supply and a fuel metering valve and variable geometry for the power plant including servo actuating mechanisms for the fuel metering valve and variable geometry, a fuel pumping system, is described to supply pressurized fuel for the servo actuating mechanisms and for the engine working fluid medium. The pumping system includes a centrifugal pump solely supplying the fuel to the fuel metering valve to be delivered to the power plant for its working fluid medium, a positive displacement pump in parallel with the centrifugal pump and solely to supply pressurized fuel to the servo actuating mechanisms for the fuel metering valve and for the variable geometry, and a boost pump means disposed in serial relationship with the positive displacement pump and the centrifugal pump for augmenting the pressure supplied by the positive displacement pump and the centrifugal pump during predetermined operating conditions of the power plant. The combined boost pump and centrifugal pump capability is sufficient to satisfy the vapor to liquid ratio requirements of the power during its entire operating envelope.

  18. Centrifugal gas-phase transition magnetophoresis (GTM)--a generic method for automation of magnetic bead based assays on the centrifugal microfluidic platform and application to DNA purification.

    PubMed

    Strohmeier, Oliver; Emperle, Alexander; Roth, Günter; Mark, Daniel; Zengerle, Roland; von Stetten, Felix

    2013-01-01

    Transportation of magnetic beads between different reagents plays a crucial role in many biological assays e.g. for purification of biomolecules or cells where the beads act as a mobile solid support. Therefore, usually a complex set-up either for fluidic processing or for manipulation of magnetic beads is required. To circumvent these drawbacks, we present a facile and automated method for the transportation of magnetic beads between multiple microfluidic chambers on a centrifugal microfluidic cartridge "LabDisk". The method excels by requiring only one stack of stationary permanent magnets, a specific microfluidic layout without actively controlled valves and a predefined frequency protocol for rotation of the LabDisk. Magnetic beads were transported through three fluidically separated chambers with a yield of 82.6% ± 3.6%. Bead based DNA purification from a dilution series of a Listeria innocua lysate and from a lambda phage DNA standard was demonstrated where the three chambers were used for binding, washing and elution of DNA. Recovery of L. innocua DNA was up to 68% ± 24% and for lambda phage DNA 43% ± 10% compared to manual reference purification in test tubes. Complete purification was conducted automatically within 12.5 min. Since all reagents can be preloaded onto the LabDisk prior to purification, no further hands-on steps are required during processing. Due to its modular and generic character, the presented method could also be adapted to other magnetic bead based assays e.g. to immunoassays or protein affinity purification, solely requiring the adjustment of number and volumes of the fluidic chambers. PMID:23142800

  19. Fluid-structure interaction analysis and lifetime estimation of a natural gas pipeline centrifugal compressor under near-choke and near-surge conditions

    NASA Astrophysics Data System (ADS)

    Ju, Yaping; Liu, Hui; Yao, Ziyun; Xing, Peng; Zhang, Chuhua

    2015-10-01

    Up to present, there have been no studies concerning the application of fluid-structure interaction (FSI) analysis to the lifetime estimation of multi-stage centrifugal compressors under dangerous unsteady aerodynamic excitations. In this paper, computational fluid dynamics (CFD) simulations of a three-stage natural gas pipeline centrifugal compressor are performed under near-choke and near-surge conditions, and the unsteady aerodynamic pressure acting on impeller blades are obtained. Then computational structural dynamics (CSD) analysis is conducted through a one-way coupling FSI model to predict alternating stresses in impeller blades. Finally, the compressor lifetime is estimated using the nominal stress approach. The FSI results show that the impellers of latter stages suffer larger fluctuation stresses but smaller mean stresses than those at preceding stages under near-choke and near-surge conditions. The most dangerous position in the compressor is found to be located near the leading edge of the last-stage impeller blade. Compressor lifetime estimation shows that the investigated compressor can run up to 102.7 h under the near-choke condition and 200.2 h under the near-surge condition. This study is expected to provide a scientific guidance for the operation safety of natural gas pipeline centrifugal compressors.

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

    SciTech Connect

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

    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.

  1. Energy Savings for Centrifugal Compressors 

    E-print Network

    Fisher, D.

    2011-01-01

    by changing to a close clearance abradable seal material. ANTI-FOULANT COATING ?Fouling is a common problem in centrifugal compressors for certain processes. Fouling refers to the buildup of solids, often called foulant (see Fig. 9), usually... Centrifugal Compressor Depending on the service, fouling substances may come from outside the machine or be generated internally. For example, in ethylene cracked gas compression, fouling results from the polymerization reactions intrinsic...

  2. Centrifugal pyrocontactor

    DOEpatents

    Chow, Lorac S. (Willowbrook, IL); Leonard, Ralph A. (River Forest, IL)

    1993-01-01

    A method 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.

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. Centrifuges Replacement Study Proposal

    E-print Network

    Iqbal, Muhammad

    2005-12-16

    Primarily this paper was written to provide a general understanding of centrifuging phenomenon, invention and brief historical developments of centrifuges and their application in industrial world. Part of this paper is specifically dedicated to a...

  8. Gas bearings. [fluid lubrication theory of sliding contact surfaces

    NASA Technical Reports Server (NTRS)

    Pan, C. H. T.

    1980-01-01

    The present work deals with the fundamentals of gas lubrication theory, which forms the foundation of all analytical design tools for gas bearings. Most of the hard lessons learned in the past are outlined with reference to dry contact, debris ingestion, sliding speed, and chemical stability of lubricant. The mathematical theory of gas lubrication is described for scaling rules in thin-film viscous flow, momentum conservation, mass conservation, energy conservation, isothermal gas bearing theory, coupling effects, and global bearing characteristics. Particular attention is given to the governing differential equations for common bearing configurations. Also discussed are representative solutions of self-acting gas bearings, externally pressurized bearings, and time-dependent effects.

  9. 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.

  10. Theories and Conflict: The Origins of Natural Gas. Instructional Materials.

    ERIC Educational Resources Information Center

    Anderson, Susan

    This unit explores a recent and controversial theory of the origin of much of the Earth's natural gas and oil. The materials provided will give students the opportunity to: (1) gain an understanding of science and what is involved in the acceptance or rejection of theories; (2) learn about fossil fuels, especially natural gas; (3) learn the…

  11. 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...

  12. Centrifugal pump failures.

    PubMed

    Kolff, J; Ankney, R N; Wurzel, D; Devineni, R

    1996-09-01

    Centrifugal pumps will not pass gross quantities of gaseous emboli due to the nonocclusive nature of the pump. However, retrograde flow can occur under circumstances that include: product malfunctions, low flows, and human errors. Negative pressure created by falling arterial perfusate can draw air into the cannula. Food and Drug Administration (FDA) records about centrifugal pump malfunctions were obtained. Out of 350,000 cases completed with centrifugal pumps over a 23 month period, the FDA received reports of 68 malfunctions, 22 electrical burning smells, and three speed surges, yielding a failure rate of 1 in 3,763 cases. FDA records revealed five death reports and three serious injury reports. A survey was sent to 2,424 Society of Thoracic Surgeons' members to obtain more information; 285 who use centrifugal pumps responded. Sixty surgeons (21%) reported 108 malfunctions, including 46 complete pump failures. Fifty-one of 243 surgeons (21%) who use centrifugal pumps for bypass reported that perfusionists have forgotten to clamp the pump line, resulting in backflow. We conclude centrifugal pumps are generally safe, but malfunctions, low flows, and human errors can lead to retrograde flow and occasionally air embolization. There are valves that can be added to the bypass circuitry to prevent this risk. PMID:10163498

  13. 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.; Garrard, D.

    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.

  14. 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; Swinhoe, Martyn T; Moran, Bruce W; Lebrun, Alain

    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.

  15. Energy recuperation centrifuge

    SciTech Connect

    Schlegel, R. F.; Bourassin, R. P.; Laparetre, M. A.

    1985-04-02

    Centrifuge comprising two drums having coaxial horizontal axes. The inner drum carries a set of dishes and, on the periphery, a scraper screw. A sludge chamber is provided at one end of the outer drum and, by way of passages adapted to be closed by a discharge device, is in communication with the outside. The centrifuge is provided with a double energy recuperation device comprising a centripetal wheel and a ring of ejectors fastened to the inner drum, together with blading fixed opposite the ejectors. The ejectors are so directed that the absolute speed of the fluid leaving the centrifuge is low. The discharge device comprises an overflow continuously fed in order to hold, by pressure, a movable plate in the closed position in front of the passages.

  16. 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.

  17. 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.

  18. Centrifugal pump design

    SciTech Connect

    Hickman, R.S.

    1986-06-01

    This report describes the program which permits the design of a centrifugal pump for use with water. The user enters the main design characteristics required and the program carries out the design. The program varies the number of impeller blades in order to optimize the net hydraulic efficiency of the pump. (FI)

  19. 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.

  20. Predicting Droplet Formation on Centrifugal Microfluidic Platforms

    NASA Astrophysics Data System (ADS)

    Moebius, Jacob Alfred

    Centrifugal microfluidics is a widely known research tool for biological sample and water quality analysis. Currently, the standard equipment used for such diagnostic applications include slow, bulky machines controlled by multiple operators. These machines can be condensed into a smaller, faster benchtop sample-to-answer system. Sample processing is an important step taken to extract, isolate, and convert biological factors, such as nucleic acids or proteins, from a raw sample to an analyzable solution. Volume definition is one such step. The focus of this thesis is the development of a model predicting monodispersed droplet formation and the application of droplets as a technique for volume definition. First, a background of droplet microfluidic platforms is presented, along with current biological analysis technologies and the advantages of integrating such technologies onto microfluidic platforms. Second, background and theories of centrifugal microfluidics is given, followed by theories relevant to droplet emulsions. Third, fabrication techniques for centrifugal microfluidic designs are discussed. Finally, the development of a model for predicting droplet formation on the centrifugal microfluidic platform are presented for the rest of the thesis. Predicting droplet formation analytically based on the volumetric flow rates of the continuous and dispersed phases, the ratios of these two flow rates, and the interfacial tension between the continuous and dispersed phases presented many challenges, which will be discussed in this work. Experimental validation was completed using continuous phase solutions of different interfacial tensions. To conclude, prospective applications are discussed with expected challenges.

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

    NASA Astrophysics Data System (ADS)

    Phillips, Scott; Dain, Yefim; Lueptow, Richard M.

    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 the theory for vibrational relaxation of gas molecules. The concept for a gas composition sensor is demonstrated theoretically for nitrogen-methane-water and hydrogen-oxygen-water mixtures. For a three-component gas mixture, the measured sound speed and acoustic attenuation each define separate lines in the composition plane of two of the gases. The intersection of the two lines defines the gas composition. It should also be possible to use the concept for mixtures of more than three components, if the nature of the gas composition is known to some extent.

  2. 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.

  3. Centrifugally decoupling touchdown bearings

    SciTech Connect

    Post, Richard F

    2014-06-24

    Centrifugally decoupling mechanical bearing systems provide thin tensioned metallic ribbons contained in a support structure. This assembly rotates around a stationary shaft being centered at low speeds by the action of the metal ribbons. Tension springs are connected on one end to the ribbons and on the other end to the support structure. The ribbons pass through slots in the inner ring of the support structure. The spring preloading thus insures contact (or near-contact) between the ribbons and the shaft at rotation speeds below the transition speed. Above this speed, however, the centrifugal force on the ribbons produces a tensile force on them that exceeds the spring tensile force so that the ribbons curve outward, effectively decoupling them from mechanical contact with the shaft. They still remain, however, in position to act as a touchdown bearing in case of abnormally high transverse accelerations.

  4. Centrifugal unbalance detection system

    DOEpatents

    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.

  5. Centrifugal effects in Skyrmeons

    SciTech Connect

    Braaten, E.

    1984-01-01

    We give a qualitative discussion of centrifugal effects in the Skyrme model and methods for treating these effects. We show that there may be states in the spectrum which would not appear in a semiclassical expansion about the static soliton solution. We consider semiclassical expansions about static solutions and about uniformly-rotating solutions, and discuss the validity and limitations of both approaches. 11 references.

  6. LMR (liquid metal reactor) centrifugal pump coastdowns

    SciTech Connect

    Dunn, F.E.; Malloy, D.J.

    1987-01-01

    A centrifugal pump model which describes the interrelationships of the pump discharge flowrate, pump speed, shaft torque and dynamic head has been implemented based upon existing models. Specifically, the pump model is based upon the dimensionless-homologous pump theory of Wylie and Streeter. Given data from a representative pump, homologous theory allows one to predict the transient characteristics of similarly sized pumps. This homologous pump model has been implemented into both the one-dimensional SASSYS-1 systems analysis code and the three-dimensional COMMIX-1A code. Comparisons have been made both against other pump models (CRBR) and actual pump coastdown data (EBR-II and FFTF). Agreement with this homologous pump model has been excellent. Additionally, these comparisons indicate the validity of applying the medium size pump data of Wylie and Streeter to a range of typical LMR centrifugal pumps.

  7. 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.

  8. 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.

  9. 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.; Hawkins Erpenbeck, Heather; Boyer, Brian D.

    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.

  10. 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. __________________________________________________

  11. 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.

  12. 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.; Garrard, D.

    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.

  13. 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 to Use Centricon Centrifugal Filter Devices ...... 5 Device Storage

  14. 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.

  15. 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).

  16. National geotechnical centrifuge

    NASA Technical Reports Server (NTRS)

    Hallam, J. A.; Kunz, N.; Vallotton, W. C.

    1982-01-01

    A high G-ton centrifuge, able to take a 2700 kg (6000 lb) payload up to 300 G, is described. The stability of dams and embankments, the bearing capacity of soil foundations, and the dynamic behavior of foundations due to vibration of machinery are examples of applications. A power rating of 6,000 kW (9,000 hp) was established for the motor. An acceptable maximum speed of 70 rpm was determined. A speed increase with a ratio of 1:3 is discussed. The isolated tension straps, the anti-spreader bar and the flexwall bucket, and safety precautions are also discussed.

  17. Performance analysis of mini centrifugal pump with splitter blades

    NASA Astrophysics Data System (ADS)

    Shigemitsu, T.; Fukutomi, J.; Wada, T.; Shinohara, H.

    2013-12-01

    Design method for a mini centrifugal pump is not established because the internal flow condition for these small-sized fluid machines is not clarified and conventional theory is not suitable for small-sized pumps. Then, a semi-open impeller for the mini centrifugal pump with 55mm impeller diameter is adopted in this research to take simplicity and maintenance into consideration. Splitter blades are adopted in this research to improve the performance and internal flow condition of mini centrifugal pump having large blade outlet angle. The performance tests are conducted with these rotors in order to investigate the effect of the splitter blades on the performance and internal flow condition of the mini centrifugal pump. A three dimensional steady numerical flow analysis is conducted to analyze rotor, volute efficiency and loss caused by a vortex. It is clarified from the experimental results that the performance of the mini centrifugal pump is improved by the effect of the splitter blades. Flow condition at outlet of the rotor becomes uniform and back flow regions are suppressed in the case with the splitter blades. Further, the volute efficiency increases and the vortex loss decreases. In the present paper, the performance of the mini centrifugal pump is shown and the flow condition is clarified with the results of the experiment and the numerical flow analysis. Furthermore, the performance analyses of the mini centrifugal pumps with and without the splitter blades are conducted.

  18. Centrifuge treatment of coal tar

    SciTech Connect

    L.A. Kazak; V.Z. Kaidalov; L.F. Syrova; O.S. Miroshnichenko; A.S. Minakov

    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.

  19. 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.

  20. Advances in electron kinetics and theory of gas discharges

    SciTech Connect

    Kolobov, Vladimir I.; The University of Alabama in Huntsville, Huntsville, Alabama 35899

    2013-10-15

    “Electrons, like people, are fertile and infertile: high-energy electrons are fertile and able to reproduce.”—Lev TsendinModern physics of gas discharges increasingly uses physical kinetics for analysis of non-equilibrium plasmas. The description of underlying physics at the kinetic level appears to be important for plasma applications in modern technologies. In this paper, we attempt to grasp the legacy of Professor Lev Tsendin, who advocated the use of the kinetic approach for understanding fundamental problems of gas discharges. We outline the fundamentals of electron kinetics in low-temperature plasmas, describe elements of the modern kinetic theory of gas discharges, and show examples of the theoretical approach to gas discharge problems used by Lev Tsendin. Important connections between electron kinetics in gas discharges and semiconductors are also discussed. Using several examples, we illustrate how Tsendin's ideas and methods are currently being developed for the implementation of next generation computational tools for adaptive kinetic-fluid simulations of gas discharges used in modern technologies.

  1. 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.

  2. 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.

  3. Centrifugal pump impeller

    SciTech Connect

    Lovisetto, P.

    1988-01-19

    An impeller for a centrifugal pump is described comprising: a rotatable impeller shaft; circumferentially spaced vanes mounted for rotation with the impeller shaft, the vanes extending outwardly relative to the impeller shaft and each including first and second axially-spaced edges; first and second axially-spaced cover members for vanes, the cover members being mounted for rotation with the impeller shaft and extending outwardly relative to the axial direction of the impeller shaft, the first cover member being disposed adjacent to the first edges of the vanes and the second cover member being disposed adjacent to the second edges of the vanes so as to provide an impeller chamber between the first and second cover members which is divided into subchambers by the vanes. One of the first and second cover members has a centrally disposed inlet opening therethrough for admitting fluid into the impeller chamber to then be conducted outwardly upon rotation of the impeller shaft; and the fist cover member being so constructed and mounted relative to the vanes that a portion thereof is free to flex axially away from respective portions of the first edges of the vanes in response to fluid pressure pulsations within the impeller chamber to temporarily increase the distance between the portion of the first cover and the respective portions of the first edges of the vanes.

  4. 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

    ... 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... holder of materials licenses SNM-7003 and SNM-2011 for the American Centrifuge Lead Cascade...

  5. Sandia National Laboratories 8. 8 metre (29-foot) and 10. 7-metre (35-foot) centrifuge facilities

    SciTech Connect

    Adams, P.H.; Ault, R.L.; Fulton, D.L.

    1980-05-01

    This report outlines the capabilities and limitations of the two centrifuges and gives other details which must be considered in preparing test specifications and designing fixtures, gives the theory and terminology of centrifuge testing, and describes the layout, operating principles, support functions, and reference material for each facility.

  6. 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.

  7. 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.

  8. Chem. Educator 2003, 8, 237237 237 An Alternative Derivation of Gas Pressure Using the Kinetic Theory

    E-print Network

    Rioux, Frank

    : The kinetic theory is used to derive the pressure of an ideal gas assuming that the gas occupies a spherical container of diameter D. General chemistry and physical chemistry texts that use the kinetic theory of the container as postulated by the kinetic theory. Consider a molecule labeled i of mass m and velocity vi

  9. On the characteristics of centrifugal-reciprocating machines. [cryogenic coolers

    NASA Technical Reports Server (NTRS)

    Higa, W. H.

    1980-01-01

    A method of compressing helium gas for cryogenic coolers is presented which uses centrifugal force to reduce the forces on the connecting rod and crankshaft in the usual reciprocating compressor. This is achieved by rotating the piston-cylinder assembly at a speed sufficient for the centrifugal force on the piston to overcome the compressional force due to the working fluid. The rotating assembly is dynamically braked in order to recharge the working space with fluid. The intake stroke consists of decelerating the rotating piston-cylinder assembly and the exhaust stroke consists of accelerating the assembly.

  10. An Attack on Centrifugal Costs 

    E-print Network

    Murray, P. F.

    1985-01-01

    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 Chocolate Bayou is using... discussed involve the addition of a variable speed turbine drive, the removal of ex cess system pressure drop, motor speed changes and variable drive units, and the matching of pumps to systems. INTRODUCTION The Monsanto Chocolate Bayou plant, a...

  11. 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.

  12. 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.

  13. lambda Phi^4 Theory From a Particle-Gas Viewpoint

    E-print Network

    M. Consoli; P. M. Stevenson

    1997-11-24

    We discuss the physics of the 3+1 dimensional lambda Phi^4 quantum field theory in terms of the statistical mechanics of a gas of particles (`atoms') that interact via a -1/r^3-plus-hard-core potential. The hard-core potential, delta^(3)(r), arises from the bare vertex diagram, while the attractive, long-range -1/r^3 potential is due to exchange of a particle pair via the t,u-channel "fish" diagram. (Higher-order diagrams preserve this form of the interparticle potential.) For sufficiently small atom mass, the lowest-energy state is not the `empty' state with no atoms, but a state with a non-zero density of spontaneously created atoms, Bose-condensed in the zero-momentum mode. This corresponds to the spontaneous-symmetry-breaking phase transition, and the `phonon' excitations of the Bose condensate correspond to Higgs particles. The important point is that the phase transition happens while the atom's physical mass m is still positive: it does not wait until m^2 passes through zero and becomes negative, contrary to the assumption of a second-order transition, on which renormalization-group-improved perturbation theory is based.

  14. A Kinetic Theory of a Weakly Interacting Bosonic Gas

    NASA Astrophysics Data System (ADS)

    Walser, R.; Williams, J.; Cooper, J.; Holland, M.

    1998-05-01

    Kinetic theories of cold quantum gases have gained renewed interest after Bose-Einstein condensation has been achieved in 1995 with externally trapped, dilute alkali gases (E. Cornell and C. Wieman). While such systems have been studied theoretically in the 1950-60's extensively, they where mainly considered as precursor theories for strongly interacting systems, such as liquid helium. Thus, most of the available results are focused on spatially homogeneous systems in contact with thermal reservoirs. However, the spatial inhomogeneity which results from the confinement of the atom cloud, as well as the isolation from external influences are essential ingredients of present day's experiments. We will present a kinetic description of a weakly interacting, trapped and condensed gas within a micro canonical ensemble. Based on a set of master variables, i.e. mean fields < hat?x > and (normal) single particle densities < (hat?^_x-< hat?^x >) (hat?_y-< hat?y >)>, we will establish a set of self-consistent kinetic equations. We will present numerical results and discuss various aspects.

  15. 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.

  16. 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.

  17. 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.

  18. Contributions to the Theory of Gas --> Liquid Condensation.

    NASA Astrophysics Data System (ADS)

    Mohanty, Udayan

    The cluster expansion of the classical and the quantum canonical partition function is shown to be related to the Bell polynomials. This observation enables one to derive a recursion relation for the partition function. The recursion relation renders the numerical evaluation of thermodynamic quantities tractable. The mathematical structure of the partition function for volume independent cluster integrals (b(,l)(T)) is shown to be connected to the Umbral algebra recently developed by Rota. This algebra is used to rederive Mayer's "first theorem". For temperatures below the critical temperature, it is shown that Lennard Jones and square well fluid do not condense in the chain approximation on b(,l)(T). They are capable of displaying a gas (--->) liquid transition, however, when higher order corrections to the connected cluster integrals, like chain branching, are taken into account. The key result is the appearance of a bi-modal cluster size distribution signalling the explosive growth of microscopic molecular clusters to produce clusters of macroscopic size. A horizontal scaling of the liquid peak, as contrasted with the vertical scaling of the gas peak, clearly shows that the liquid clusters are macroscopic in macroscopic systems. A hypothesis is put forward that formation of a macroscopic array of connected rings would be signalled by the appearance of a second peak in an ensemble of average star size distribution. A physical cluster theory of vapor condensation is developed which removes the unphysical nature of the Mayer's cluster. The Week-Chandler-Andersen potential separation idea in the perturbation theory of liquids is exploited to redefine the physical clusters while retaining the exact form of Mayer's equations. The mathematical and physical cluster size distributions are calculated and compared at various temperatures and densities in the tree approximation. The crucial roles played by Mayer's monomers and dimers are pointed out. Tentative calculations reveal that the formalism developed is simple, computationally tractable and suited for an equilibrium theory of liquids. The relationship between the condensation point in the sense of Mayer and the percolation point (for fluids) which is the point where an infinite physical cluster begins to appear in the system is investigated in the ring approximation on b(,l)(T,V). The exact volume dependent b(,l)(T,V) of an ideal Bose gas is calculated under Neumann and Dirichlet boundary conditions. This set of b(,l)(T,V) is used with the above formalism to study Bose-Einstein condensation in finite systems in the canonical ensemble. A new criteria for Bose-Einstein condensation in finite systems of IBG is proposed and investigated. In the presence of an external field, the ideal Bose gas shows a bimodality in the mean cluster size distribution in the canonical ensemble. This explicit demonstration of a bimodal cluster size distribution in quantum systems is the theoretical counterpart (for finite systems) of the oft assumed phase transition and concomitant separation of particles in coordinate space.

  19. 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.

  20. High efficiency centrifugal pump

    SciTech Connect

    Nasvytis, P.J.; Jahrstorfer, G.W.

    1983-10-11

    A high speed fuel pump for a gas turnbine engine has a positively-driven shroud positioned between a main impeller and the wall of a pumping cavity to reduce impeller drag. The shroud is formed by a first disc having a boost impeller connected to its central hub portion and a second disc having a gear carried by its central hub portion. The main drive shaft assembly to which the main impeller is connected, carries a gear which meshes with gear mounted upon a shaft. The shaft also carries a gear which meshes with the gear. The gears are sized so that the shroud is driven at one-half the speed of the main impeller in order to maximize impeller drag reduction and enhance pumping capability when severe inlet conditions are present at the pump inlet.

  1. $\\lambda \\Phi^4$ Theory From a Particle-Gas Viewpoint

    E-print Network

    Consoli, M

    1997-01-01

    We discuss the physics of the 3+1 dimensional lambda Phi^4 quantum field theory in terms of the statistical mechanics of a gas of particles (`atoms') that interact via a -1/r^3-plus-hard-core potential. The hard-core potential, delta^(3)(r), arises from the bare vertex diagram, while the attractive, long-range -1/r^3 potential is due to exchange of a particle pair via the t,u-channel "fish" diagram. (Higher-order diagrams preserve this form of the interparticle potential.) For sufficiently small atom mass, the lowest-energy state is not the `empty' state with no atoms, but a state with a non-zero density of spontaneously created atoms, Bose-condensed in the zero-momentum mode. This corresponds to the spontaneous-symmetry-breaking phase transition, and the `phonon' excitations of the Bose condensate correspond to Higgs particles. The important point is that the phase transition happens while the atom's physical mass m is still positive: it does not wait until m^2 passes through zero and becomes negative, contr...

  2. Axial Segregation in a Cylindrical Centrifuge

    NASA Astrophysics Data System (ADS)

    Lee, Jonghoon; Ladd, Anthony J.

    2002-08-01

    We propose a theory for axial segregation of suspensions of non-neutrally buoyant particles in a rotating cylinder. The cylinder is oriented in the horizontal plane, so that any axial forces must arise from interparticle interactions. We show that the hydrodynamic interaction between pairs of particles produces a relative motion in the axial direction, independent of the gravitational force. If the particles are denser than the suspending fluid, differential centrifuging between particles at different radial positions leads to an at­tractive interaction, inducing a rapid growth of axial density perturbations. We suggest that this mecha­nism can explain the origin of band formation in rotating suspensions of non-neutrally buoyant particles.

  3. Axial segregation in a cylindrical centrifuge.

    PubMed

    Lee, Jonghoon; Ladd, Anthony J C

    2002-09-01

    We propose a theory for axial segregation of suspensions of non-neutrally buoyant particles in a rotating cylinder. The cylinder is oriented in the horizontal plane, so that any axial forces must arise from interparticle interactions. We show that the hydrodynamic interaction between pairs of particles produces a relative motion in the axial direction, independent of the gravitational force. If the particles are denser than the suspending fluid, differential centrifuging between particles at different radial positions leads to an at-tractive interaction, inducing a rapid growth of axial density perturbations. We suggest that this mecha-nism can explain the origin of band formation in rotating suspensions of non-neutrally buoyant particles. PMID:12225195

  4. Gas Bubbles and Gas Pancakes at Liquid/Solid Interface: A Continuum Theory Incorporated with Molecular Interactions

    E-print Network

    Zhaoxia Li; Xuehua Zhang; Lijuan Zhang; Xiaocheng Zeng; Jun Hu; Haiping Fang

    2007-10-27

    The states of gas accumulated at the liquid-solid interface are analyzed based on the continuum theory where the Hamaker constant is used to describe the long-range interaction at the microscopic scale. The Hamaker constant is always negative, whereas the gas spreading coefficient can be either sign. Despite the complexity of gas, including that the density profile may not be uniform due to absorption on both solid and liquid surfaces, we predict three possible gas states at the liquid-solid interface, i.e. complete wetting, partial wetting and pseudopartial wetting. These possible gas states correspond respectively to a gas pancake (or film) surrounded by a wet solid, a gas bubble with a finite contact angle, and a gas bubble(s) coexisting with a gas pancake. Typical thickness of the gas pancakes is at the nanoscale within the force range of the long-range interaction, whereas the radius of the gas bubbles can be large. The state of gas bubble(s) coexisting with a gas film is predicted theoretically for the first time. Our theoretical results can contribute to the development of a unified picture of gas nucleation at the liquid-solid interface.

  5. When to maintain centrifugal pumps

    SciTech Connect

    Karassik, I.J.

    1993-04-01

    Centrifugal pumps comprise critical maintenance equipment. The rationale of when to maintain them relates to a spreading tendency to contain costs in the face of tight money. Plant managers are thus entitled to a thorough analysis of whether reduced expenditures truly lower costs or actually hinder maintenance and increase costs. Absence of such an analysis hides the fact that proper and timely maintenance has a double effect: it not only reduces power consumption but also extends equipment life, and thus reduces the frequency of labor and material expenditures for scheduled or crisis maintenance. Centrifugal pump maintenance can demonstrate well the validity of this observation. The paper discusses: restoring internal clearances; real cost of renewing clearances; and monitoring clearances and pump performance.

  6. An Alternative Derivation of Gas Pressure Using the Kinetic Theory Frank Rioux

    E-print Network

    Rioux, Frank

    An Alternative Derivation of Gas Pressure Using the Kinetic Theory Frank Rioux Department container of diameter D. General chemistry and physical chemistry texts that use the kinetic theory and the surface of the container as postulated by the kinetic theory. Consider a molecule labeled i of mass m

  7. Twinning of amphibian embryos by centrifugation

    NASA Technical Reports Server (NTRS)

    Black, S. D.

    1984-01-01

    In the frog Xenopus laevis, the dorsal structures of the embryonic body axis normally derive from the side of the egg opposite the side of sperm entry. However, if the uncleaved egg is inclined at lg or centrifuged in an inclined position, this topographic relationship is overridden: the egg makes its dorsal axial structures according to its orientation in the gravitational/centrifugal field, irrespective of the position of sperm entry. Certain conditions of centrifugation cause eggs to develop into conjoined twins with two sets of axial structures. A detailed analysis of twinning provided some insight into experimental axis orientation. First, as with single-axis embryos, both axes in twins are oriented according to the direction of centrifugation. One axis forms at the centripetal side of the egg and the other forms at the centrifugal side, even when the side of sperm entry is normal to the centrifugal force vector. Second, if eggs are centrifuged to give twins, but are inclined at lg to prevent post-centrifugation endoplasmic redistributions, only single-axis embryos develop. Thus, a second redistribution is required for high-frequency secondary axis formation. This can be accomplished by lg (as in the single centrifugations) or by a second centrifugation directed along the egg's animal-vegetal axis.

  8. A Nucleation Theory for Gas-Supersaturated Liquids that Accounts for Gas Diffusion

    NASA Astrophysics Data System (ADS)

    Brereton, G. J.; Liu, X.

    2001-11-01

    Classical nucleation theory relates the rate at which embryo bubbles are formed to the reversible work required to grow a bubble of critical radius rc from random molecular activity, in the form: J ? exp-4?? r_c^2/(3kT). By setting J to a constant, this rate equation can be inverted to determine the conditions for rc under which nucleation takes place. In the case of liquids supersaturated with dissimilar gases, classical nucleation theory indicates almost no dependence on the species of dissolved gas whereas experiments indicate order-of-magnitude changes in conditions for nucleation. By modifying the nucleation rate equation to relate the formation of embryo bubbles of critical size to sufficiently energetic molecular activity for: i) carrying out the reversible work 4?? r_c^2/3; and ii) overcoming diffusive effects, which act to redissolve sub-critical-size bubbles; in the form: J?exp(-W_rev-Q_diff) /(kT) ; agreement with experiments is recovered.

  9. Preliminary study of a centrifugal-flow singlet oxygen generator

    SciTech Connect

    Shi, W; Deng, L; Yang, H; Sha, G; Zhang, C

    2008-02-28

    By using the concept of a high-pressure, gravity-independent singlet oxygen generator (SOG) proposed by Emanuel and based on the principle that a rotating fluid is capable of producing an enormous centrifugal force, a novel-type centrifugal-flow singlet oxygen generator (CFSOG) was designed and constructed. In this device, O{sub 2}({sup 1}{delta}) was generated in the reaction of gaseous Cl{sub 2} with a rotating basic hydrogen peroxide (BHP) liquid flow and then was removed from the BHP liquid phase by the centrifugal force. Meanwhile, the microdroplets formed during the Cl{sub 2}+BHP reaction were removed from the O{sub 2}({sup 1}{delta}) gas flow by the centrifugal force produced by the high-speed flow along an arc-shaped channel. Preliminary investigations showed that, because the specific reactive surface area of this SOG was noticeably larger than that of the jet-SOG normally used in current chemical oxygen-iodine lasers (COILs), the O{sub 2}({sup 1}{delta}) yield of {approx}60%, the O{sub 2}({sup 1}{delta}) partial pressure as high as 31 Torr, and chlorine utilisation higher than 96% were realised. Moreover, steady operation was obtained. (laser components)

  10. Coral reef formation theory may apply to oil, gas exploration

    SciTech Connect

    Not Available

    1990-12-10

    This paper reports a coral reef formation theory that has implications for hydrocarbon exploration. The theory states that many coral reefs and carbonate buildups from at and are dependent upon nutrient rich fluids seeping through the seabed.

  11. Theory of a Quodon Gas with Application to Precipitation Kinetics in Solids Under Irradiation

    NASA Astrophysics Data System (ADS)

    Dubinko, V.; Shapovalov, R.

    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 as high as the density of phonon gas. The quodon gas may be a powerful driver of the chemical reaction rates under irradiation, the strength of which exponentially increases with irradiation flux and may be comparable with strength of the phonon gas that exponentially increases with temperature. 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.

  12. 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

  13. 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.

  14. 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

    ... Register on November 17, 2010 (75 FR 70300), including a notice of opportunity to request a hearing, or to... USEC Inc. (American Centrifuge Lead Cascade Facility and American Centrifuge Plant); Order Approving... licenses numbers SNM- 7003 and SNM-2011 for the American Centrifuge Lead Cascade Facility (Lead...

  15. 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.

  16. 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.

  17. Two-phase flow centrifugal pump performance

    NASA Astrophysics Data System (ADS)

    Chisely, Eugene Andras

    The performance of centrifugal pumps subjected to a liquid-gas-mixture flow is a significant concern to manufacturers and to some users such as Chemical, Nuclear Power Plants, and Gas-Oil Industries. Particularly in the nuclear power industry, the prediction of performance degradation under the two-phase flow conditions occurring in a Loss of Coolant Accident (LOCA) is a significant part of the overall analysis of that accident. In this experimental work, the pressure distribution was measured in a rotating, partially shrouded, open, radial impeller and volute under a wide range of air-water two-phase flow conditions. To obtain these pressure measurements, small-diameter pressure-tap holes were drilled through the casing of the radial pump. High speed photography was used to determine the flow regime of the air-water mixture through the vane and in the volute. An analytical model was developed to predict the radial pump single- and two-phase flow pressure distribution. This distribution was compared with the test data for different suction void fractions. The physical mechanism responsible for pump performance degradation was also investigated.

  18. 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.

  19. 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, spin 70 mL of buffer solution or Milli-Q® water through filter for 5 minutes. To remove all water

  20. 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 modeling techniques in solving geotechnical engineering problems. By comparing the behavior of a soil, Japan in 1996. He worked as a consulting engineer in geotechnical engineering for 12 years in Japan

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. Rotor for centrifugal fast analyzers

    SciTech Connect

    Lee, Norman E.

    1985-01-01

    The invention is an improved photometric analyzer of the rotary cuvette type, the analyzer incorporating a multicuvette rotor of novel design. The rotor (a) is leaktight, (b) permits operation in the 90.degree. and 180.degree. excitation modes, (c) is compatible with extensively used Centrifugal Fast Analyzers, and (d) can be used thousands of times. The rotor includes an assembly comprising a top plate, a bottom plate, and a central plate, the rim of the central plate being formed with circumferentially spaced indentations. A UV-transmitting ring is sealably affixed to the indented rim to define with the indentations an array of cuvettes. The ring serves both as a sealing means and an end window for the cuvettes.

  6. Rotor for centrifugal fast analyzers

    SciTech Connect

    Lee, N. E.

    1985-04-09

    The invention is an improved photometric analyzer of the rotary cuvette type, the analyzer incorporating a multicuvette rotor of novel design. The rotor (a) is leaktight, (b) permits operation in the 90/sup 0/ and 180/sup 0/ excitation modes, (c) is compatible with extensively used Centrifugal Fast Analyzers, and (d) can be used thousands of times. The rotor includes an assembly comprising a top plate, a bottom plate, and a central plate, the rim of the central plate being formed with circumferentially spaced indentations. A UV-transmitting ring is sealably affixed to the indented rim to define with the indentations an array of cuvettes. The ring serves both as a sealing means and an end window for the cuvettes.

  7. Rotor for centrifugal fast analyzers

    SciTech Connect

    Lee, N.E.

    1984-01-01

    The invention is an improved photometric analyzer of the rotary cuvette type, the analyzer incorporating a multicuvette rotor of novel design. The rotor (a) is leaktight, (b) permits operation in the 90/sup 0/ and 180/sup 0/ excitation modes, (c) is compatible with extensively used Centrifugal Fast Analyzers, and (d) can be used thousands of times. The rotor includes an assembly comprising a top plate, a bottom plate, and a central plate, the rim of the central plate being formed with circumferentially spaced indentations. A uv-transmitting ring is sealably affixed to the indented rim to define with the indentations an array of cuvettes. The ring serves both as a sealing means and an end window for the cuvettes.

  8. 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.

  9. 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

  10. 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.

  11. The Kinetic Molecular Theory of Gases A gas consists of a collection of molecules in continuous random motion with

    E-print Network

    Rioux, Frank

    The Kinetic Molecular Theory of Gases A gas consists of a collection of molecules in continuous of the gas molecules and to calculate the bulk properties of the gas. The basic features of the kinetic molecular theory (KMT) are illustrated in the figure below. Pointlike molecules · · · , and speed

  12. Performance and internal flow condition of mini centrifugal pump with splitter blades

    NASA Astrophysics Data System (ADS)

    Shigemitsu, T.; Fukutomi, J.; Kaji, K.; Wada, T.

    2012-11-01

    Mini centrifugal pumps having a diameter smaller than 100mm are employed in many fields. But the design method for the mini centrifugal pump is not established because the internal flow condition for these small-sized fluid machines is not clarified and conventional theory is not suitable for small-sized pumps. Therefore, mini centrifugal pumps with simple structure were investigated by this research. Splitter blades were adopted in this research to improve the performance and the internal flow condition of mini centrifugal pump which had large blade outlet angle. The original impeller without the splitter blades and the impeller with the splitter blades were prepared for an experiment. The performance tests are conducted with these rotors in order to investigate the effect of the splitter blades on performance and internal flow condition of mini centrifugal pump. On the other hand, a three dimensional steady numerical flow analysis is conducted with the commercial code (ANSYS-CFX) to investigate the internal flow condition in detail. It is clarified from the experimental results that the performance of the mini centrifugal pump is improved by the effect of the splitter blades. The blade-to-blade low velocity regions are suppressed in the case with the splitter blades and the total pressure loss regions are decreased. The effects of the splitter blades on the performance and the internal flow condition are discussed in this paper.

  13. 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.

  14. 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 ...

  15. 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, ...

  16. 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 ...

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  1. Applications of radiative perturbation theory to changes in absorbing gas

    NASA Astrophysics Data System (ADS)

    Box, M. A.; Loughlin, P. E.; Samaras, M.; Trautmann, T.

    1997-02-01

    The perturbation formulations presented in papers published by Box et al. have been investigated for homogeneous and real atmospheres by perturbing the optical thickness of an absorbing gas, with the emphasis in this paper on ozone changes. Both exponential and linear perturbation formulations were investigated for a model with plane parallel geometry and different solar zenith angles. The results for the exponential perturbation predictions for net surface fluxes were very good in all cases where the solar zenith angle was less than 60°. However, where the solar zenith angle was increased past 60°, the range of validity of the perturbation models was clearly reduced. Applications to action spectrum integrals are presented which show that the approach is able to provide good results for zenith angles up to 60°, with accuracy past this angle being better than for nonintegrated effects.

  2. Flows and particles with centrifugal (centripetal) and Coriolis' velocities and accelerations. Hubble's law in spaces with affine connections and metrics

    E-print Network

    Sawa Manoff

    2003-02-04

    The notions of centrifugal (centripetal) and Coriols' velocities and accelerations are introduced and considered in spaces with affine connections and metrics as velocities and accelerations of flows of mass elements (particles) moving in space-time. It is shown that these types of velocities and accelerations are generated by the relative motions between the mass elements. They are closely related to the kinematic characteristics of the relative velocity and the relative acceleration. The null (isotropic) vector fields are considered and their relations with the centrifugal (centripetal) velocity are established. The centrifugal (centripetal) velocity is found to be in connection with the Hubble law and the generalized Doppler effect in spaces with affine connections and metrics. The centrifugal (centripetal) acceleration could be interpreted as gravitational acceleration as it has been done in the Einstein theory of gravitation. This fact could be used as a basis for working out of new gravitational theories in spaces with affine connections and metrics.

  3. Theory of inert gas-condensing vapor thermoacoustics: transport equations.

    PubMed

    Slaton, William V; Raspet, Richard; Hickey, Craig J; Hiller, Robert A

    2002-10-01

    The preceding paper [J. Acoust. Soc. Am. 112, 1414-1422 (2002)] derives the propagation equation for sound in an inert gas-condensing vapor mixture in a wet-walled pore with an imposed temperature gradient. In this paper the mass, enthalpy, heat, and work transport equations necessary to describe the steady-state operation of a wet-walled thermoacoustic refrigerator are derived and presented in a form suitable for numerical evaluation. The requirement that the refrigerator operate in the steady state imposes zero mass flux for each species through a cross section. This in turn leads to the evaluation of the mass flux of vapor in the system. The vapor transport and heat transport are shown to work in parallel to produce additional cooling power in the wet refrigerator. An idealized calculation of the coefficient of performance (COP) of a wet-walled thermoacoustic refrigerator is derived and evaluated for a refrigeration system. The results of this calculation indicate that the wet-walled system can improve the performance of thermoacoustic refrigerators. Several experimental and practical questions and problems that must be addressed before a practical device can be designed and tested are described. PMID:12398450

  4. 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.

  5. "Centrifugal Forces," Spring, 2015 Centrifugal Forces: Reading Russia's Regional Identities and Initiatives

    E-print Network

    Huang, Wei

    "Centrifugal Forces," Spring, 2015 Centrifugal Forces: Reading Russia's Regional Identities, Virginia March 26-28, 2015 Call for Papers Contemporary Russia has been described as a "country of broken million people) remain unheard and underestimated. At first glance, Russia's regions often appear to mimic

  6. 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

    ...American Centrifuge Plant; Notice of Receipt of...Comments and Request a Hearing AGENCY: Nuclear Regulatory...opportunity to request a hearing and provide written comments...DATES: A request for a hearing must be filed by December...the American Centrifuge Plant, respectively, is...

  7. Theory of attosecond time delay in double photoionization of noble gas atoms J. M. Dahlstrom

    E-print Network

    Kheifets, Anatoli

    Theory of attosecond time delay in double photoionization of noble gas atoms J. M. Dahlstr¨om and E ACT 0200, Australia (Dated: June 4, 2013) We present a theoretical interpretation of attosecond time of the increasingly fast primary photoelec- tron [5]. Recently, with the advent of attosecond science, ex- perimental

  8. Fundamental equations of a mixture of gas and small spherical solid particles from simple kinetic theory.

    NASA Technical Reports Server (NTRS)

    Pai, S. I.

    1973-01-01

    The fundamental equations of a mixture of a gas and pseudofluid of small spherical solid particles are derived from the Boltzmann equation of two-fluid theory. The distribution function of the gas molecules is defined in the same manner as in the ordinary kinetic theory of gases, but the distribution function for the solid particles is different from that of the gas molecules, because it is necessary to take into account the different size and physical properties of solid particles. In the proposed simple kinetic theory, two additional parameters are introduced: one is the radius of the spheres and the other is the instantaneous temperature of the solid particles in the distribution of the solid particles. The Boltzmann equation for each species of the mixture is formally written, and the transfer equations of these Boltzmann equations are derived and compared to the well-known fundamental equations of the mixture of a gas and small solid particles from continuum theory. The equations obtained reveal some insight into various terms in the fundamental equations. For instance, the partial pressure of the pseudofluid of solid particles is not negligible if the volume fraction of solid particles is not negligible as in the case of lunar ash flow.

  9. 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.

  10. Internally-cooled centrifugal compressor with cooling jacket formed in the diaphragm

    DOEpatents

    Moore, James J.; Lerche, Andrew H.; Moreland, Brian S.

    2014-08-26

    An internally-cooled centrifugal compressor having a shaped casing and a diaphragm disposed within the shaped casing having a gas side and a coolant side so that heat from a gas flowing though the gas side is extracted via the coolant side. An impeller disposed within the diaphragm has a stage inlet on one side and a stage outlet for delivering a pressurized gas to a downstream connection. The coolant side of the diaphragm includes at least one passageway for directing a coolant in a substantially counter-flow direction from the flow of gas through the gas side.

  11. Comparison between theory and experiment for universal thermodynamics of a homogeneous, strongly correlated Fermi gas

    SciTech Connect

    Hu Hui; Liu Xiaji; Drummond, Peter D.

    2011-06-15

    We compare the theoretical predictions for universal thermodynamics of a homogeneous, strongly correlated Fermi gas with the latest experimental measurements reported by the ENS group [S. Nascimbene et al., Nature (London) 463, 1057 (2010)] and the Tokyo group [M. Horikoshi et al., Science 327, 442 (2010)]. The theoretical results are obtained using two diagrammatic theories, together with a virial expansion theory combined with a Pade approximation. We find good agreement between theory and experiment. In particular, the virial expansion, using a Pade approximation up to third order, describes the experimental results extremely well down to the superfluid transition temperature, T{sub c{approx}}0.16T{sub F}, where T{sub F} is the Fermi temperature. The comparison in this work complements our previous comparative study on the universal thermodynamics of a strongly correlated but trapped Fermi gas. The comparison also raises interesting issues about the unitary entropy and the applicability of the Pade approximation.

  12. Conductometric study of erythrocytes during centrifugation. II. Erythrocyte deformability.

    PubMed

    Pribush, A; Meyerstein, D; Meyerstein, N

    1995-05-17

    Erythrocyte deformability was studied by continuous reading of sediment conductance during centrifugation. The decrease in sediment conductivity during centrifugation reflects erythrocyte deformation in the pellet. The degree of erythrocyte deformation depends on the duration of centrifugation and the magnitude of centripetal acceleration. When constant centrifugal force is applied over an extended period of time, a gradual decrease in pellet conductivity occurs. Stepwise enhancement of centripetal acceleration during centrifugation induces a rapid increase in erythrocyte deformation. After centrifugation, the relaxation of erythrocyte deformation is observed. However, the relaxation and the recovery of cell shape are incomplete. The difference in compressibility of previously centrifuged and noncentrifuged cells demonstrates that centrifugation causes irreversible alteration in erythrocyte deformability. The results show that the time-dependent resistance of erythrocyte sediment during centrifugation may serve as a useful index for the kinetics of erythrocyte deformation. PMID:7766698

  13. Capabilities of Numerical Simulation of Multiphase Flows in Centrifugal Pumps using Modern CFD Software

    E-print Network

    Kochevsky, A N

    2005-01-01

    The paper describes capabilities of numerical simulation of liquid flows with solid and/or gas admixtures in centrifugal pumps using modern commercial CFD software packages, with the purpose to predict performance curves of the pumps treating such media. In particular, the approaches and multiphase flow models available in the package CFX-5 are described; their advantages and disadvantages are analyzed.

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

    SciTech Connect

    Wahlberg, C.

    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.

  15. Unsteady internal flow conditions of mini-centrifugal pump with splitter blades

    NASA Astrophysics Data System (ADS)

    Shigemitsu, T.; Fukutomi, J.; Kaji, K.; Wada, T.

    2013-02-01

    Mini centrifugal pumps having a diameter smaller than 100mm are employed in many fields. But the design method for the mini centrifugal pump is not established because the internal flow condition for these small-sized fluid machines is not clarified and conventional theory is not suitable for small-sized pumps. Therefore, mini centrifugal pumps with simple structure were investigated by this research. Splitter blades were adopted in this research to improve the performance and the internal flow condition of mini centrifugal pump which had large blade outlet angle. The original impeller without the splitter blades and the impeller with the splitter blades were prepared for experiment. The performance tests are conducted with these rotors in order to investigate the effect of the splitter blades on performance and internal flow condition of mini centrifugal pump. On the other hand, a three dimensional unsteady numerical flow analysis was conducted to investigate the change of the internal flow according to the rotor rotation. It is clarified from the experimental results that the performance of the mini centrifugal pump is improved by the splitter blades. The blade-to-blade low velocity region was suppressed in the case with the splitter blades. In addition to that, the unsteady flows near the volute casing tongue were suppressed due to the splitter blades. In the present paper, the performance of the mini centrifugal pump is shown and the unsteady flow condition is clarified with the results of the numerical flow analysis. Furthermore, the effects of the splitter blades on the performance and the unsteady internal flow condition are investigated.

  16. Elementary gas kinetic theory. Today we will give kinetic theory definitions to main macroscopic

    E-print Network

    Alexeenko, Alina

    . #12;8 Avogadro's Law Number of molecules in a volume of gas is a quantity of particles in a given of C12 =6.022x1023 atoms. NA =6.022x1023 ­ Avogadro number. The volume V0 occupied by a mole of ideal normal to dS for molecules with velocity = where nv ­ number density of molecules with velocity

  17. Mechanisms of flow through compressible porous beds in sedimentation, centrifugation, deliquoring, and ceramic processing

    SciTech Connect

    1996-01-25

    The major topics covered in the investigation include: centrifugation; cake filtration; sedimentation and thickening; capillary suction operations; ceramics, slip casting; optimization studies; and wastewater. The research program was aimed at the specific areas of solid/liquid separation including sedimentation, thickening, cake filtration, centrifugation, expression, washing, deep-bed filtration, screening, and membrane separation. Unification of the theoretical approaches to the various solid/liquid separation operations was the principle objective of the research. Exploring new aspects of basic separation mechanisms, verification of theory with experiment, development of laboratory procedures for obtaining data for design, optimizing operational methods, and transferring the results to industry were part of the program.

  18. 26. RW Meyer Sugar Mill: 18761889. Centrifugals, 1879, 1881. Manufacturer, ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    26. RW Meyer Sugar Mill: 1876-1889. Centrifugals, 1879, 1881. Manufacturer, unknown. Supplied by Honolulu Ironworks, Honolulu, Hawaii, 1879, 1881. View: Historical view, 1934, from T. T. Waterman collection, Hawaiian Sugar Planters' Association. Once the molasses was separated from the sugar crystals it flowed through the spouts in the base of the centrifugals. The centrifugals' pulleys can be seen underneath the centrifugal. The centrifugal on the right has been reinforced with seven metal bands. The handles for the clutch mechanism are located above the centrifugal. - R. W. Meyer Sugar Mill, State Route 47, Kualapuu, Maui County, HI

  19. Preventing cavitation in high energy centrifugal pumps

    SciTech Connect

    Garbers, A.W.F.; Wasfi, A.K. Ltd. )

    1990-07-01

    Large-eye impellers for high energy centrifugal pumps were developed to meet the specification of reduced NPSH{sub r} at rated flow conditions. Unfortunately, this improved NPSH performance was not without adverse tradeoffs because an abnormal increase in noise, vibration and cavitation erosion were experienced at low flows. Centrifugal pumps are often used under widely varying and adverse conditions, and in the case of high energy and large-eye impeller pumps, these conditions should be evaluated very carefully. At petrochemical complexes in Secunda in the Republic of South Africa, a centrifugal pump application for lean carbonate solution experienced frequent failures. An investigation and literature survey indicated the cause was low flow cavitation. The purpose of this article is but to give design guidelines as obtained from literature and experience.

  20. 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.

  1. 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.

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

    SciTech Connect

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

    2015-04-21

    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.

  3. 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.

  4. 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.

  5. 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.

  6. Detection methods for centrifugal microfluidic platforms.

    PubMed

    Burger, Robert; Amato, Letizia; Boisen, Anja

    2016-02-15

    Centrifugal microfluidics has attracted much interest from academia as well as industry, since it potentially offers solutions for affordable, user-friendly and portable biosensing. A wide range of so-called fluidic unit operations, e.g. mixing, metering, liquid routing, and particle separation, have been developed and allow automation and integration of complex assay protocols in lab-on-a-disc systems. Besides liquid handling, the detection strategy for reading out the assay is crucial for developing a fully integrated system. In this review, we focus on biosensors and readout methods for the centrifugal microfluidics platform and cover optical as well as mechanical and electrical detection principles. PMID:26166363

  7. System analysis of plasma centrifuges and sputtering

    NASA Technical Reports Server (NTRS)

    Hong, S. H.

    1978-01-01

    System analyses of cylindrical plasma centrifuges are presented, for which the velocity field and electromagnetic fields are calculated. The effects of different electrode geometrics, induced magnetic fields, Hall-effect, and secondary flows are discussed. It is shown that speeds of 10000 m/sec can be achieved in plasma centrifuges, and that an efficient separation of U238 and U235 in uranium plasmas is feasible. The external boundary-value problem for the deposition of sputtering products is reduced to a Fredholm integral equation, which is solved analytically by means of the method of successive approximations.

  8. Wave-Driven Rotation In Centrifugal Mirrors

    SciTech Connect

    Abraham J. Fetterman and Nathaniel J. Fisch

    2011-03-28

    Centrifugal mirrors use supersonic rotation to provide axial confinement and enhanced stability. Usually the rotation is produced using electrodes, but these electrodes have limited the rotation to the Alfven critical ionization velocity, which is too slow to be useful for fusion. Instead, the rotation could be produced using radio frequency waves. A fixed azimuthal ripple is a simple and efficient wave that could produce rotation by harnessing alpha particle energy. This is an extension of the alpha channeling effect. The alpha particle power and efficiency in a simulated devices is sufficient to produce rotation without external energy input. By eliminating the need for electrodes, this opens new opportunities for centrifugal traps.

  9. 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.

  10. 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

  11. Centrifugally cast bimetallic pipe for offshore corrosion resistant pipelines

    SciTech Connect

    Yoshitake, A.; Torigoe, T.

    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.

  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. [Aquatic animals and use of centrifuge in space experiments].

    PubMed

    Ijiri, K

    2001-10-01

    There are some experiments which do not need a centrifuge apparatus in space, however, for other space experiments the use of centrifuge is indispensable as the control. The characteristics of these two types of space experiments are explained. Generally, the more quantitatively the phenomenon is analyzed, the greater the need of centrifuge apparatus becomes. The centrifuge in space can realize various gravity values ranging from 0 to 1 G, and this will extend the present biology to a more universal biology. PMID:11997593

  15. Theory of light and atom scattering in the Bose-Einstein condensate of a dilute gas

    SciTech Connect

    Avetisyan, Ya. A.; Trifonov, E. D.

    2006-11-15

    A semiclassical theory of superradiant light scattering from a Bose-Einstein condensate of a dilute gas is developed without recourse to the mean field approximation. The dynamics and spectrum of superradiant field, as well as the kinetics of formation of coherent atomic states with various translational momenta are calculated. The results are qualitatively consistent with experimental data for atoms scattered in the backward direction relative to that of the exciting laser beam propagation.

  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. 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…

  18. 21 CFR 864.5350 - Microsedimentation centrifuge.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Microsedimentation centrifuge. 864.5350 Section 864.5350 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES HEMATOLOGY AND PATHOLOGY DEVICES Automated and Semi-Automated Hematology...

  19. 21 CFR 864.5350 - Microsedimentation centrifuge.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Microsedimentation centrifuge. 864.5350 Section 864.5350 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES HEMATOLOGY AND PATHOLOGY DEVICES Automated and Semi-Automated Hematology...

  20. 21 CFR 864.5350 - Microsedimentation centrifuge.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Microsedimentation centrifuge. 864.5350 Section 864.5350 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES HEMATOLOGY AND PATHOLOGY DEVICES Automated and Semi-Automated Hematology...

  1. 21 CFR 864.5350 - Microsedimentation centrifuge.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Microsedimentation centrifuge. 864.5350 Section 864.5350 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES HEMATOLOGY AND PATHOLOGY DEVICES Automated and Semi-Automated Hematology...

  2. Centrifugal length separation of carbon nanotubes.

    PubMed

    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 approximately 2 microm 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-near-infrared 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. PMID:19053631

  3. 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.

  4. 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.

  5. 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.

  6. The Maryland Centrifugal Experiment (MCX) : Progress and Plans

    NASA Astrophysics Data System (ADS)

    Ellis, Richard; Case, Andrew; Gupta, Deepak; Hassam, Adil; Lunsford, Robert; Messer, Sarah

    2002-11-01

    The purpose of MCX is to study centrifugal confinement of plasmas and velocity shear stabilization of MHD interchange instabilities. The magnetic geometry is that of a solenoid with axisymmetric mirror end fields. Biasing of an inner core relative to the outer wall produces a radial electric field which will drive supersonic ExB azimuthal rotation and the resulting centrifugal force will contain plasma to the solenoidal portion. Major construction of the MCX facility has been completed and initial plasma discharges have been run. The solenoidal field in MCX has a maximum strength of 0.5 T, the mirror fields a maximum of 1.8 T; the mirror ratio is variable from 3-10. The vacuum vessel is 55 cm diameter at midplane with an overall axial length of 410 cm. A 10 KV, 80 KJ capacitor bank has been constructed as the power source, with upgrade capability to 18 KV and 1.0 MJ. Tests of a prototype core and insulator system at high voltage were completed and modifications are underway as well as development of differential pumping and gas puffing to control discharge formation. Glow discharge, plasma gun, and ECH (10GHZ) preionization sources are also being developed. Full operational capability of these systems and regular plasma operations are expected this upcoming year. Progress on MCX and future plans will be detailed.

  7. 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.

  8. High Technology Centrifugal Compressor for Commercial Air Conditioning Systems

    SciTech Connect

    Ruckes, John

    2006-04-15

    R&D Dynamics, Bloomfield, CT in partnership with the State of Connecticut has been developing a high technology, oil-free, energy-efficient centrifugal compressor called CENVA for commercial air conditioning systems under a program funded by the US Department of Energy. The CENVA compressor applies the foil bearing technology used in all modern aircraft, civil and military, air conditioning systems. The CENVA compressor will enhance the efficiency of water and air cooled chillers, packaged roof top units, and other air conditioning systems by providing an 18% reduction in energy consumption in the unit capacity range of 25 to 350 tons of refrigeration The technical approach for CENVA involved the design and development of a high-speed, oil-free foil gas bearing-supported two-stage centrifugal compressor, CENVA encompassed the following high technologies, which are not currently utilized in commercial air conditioning systems: Foil gas bearings operating in HFC-134a; Efficient centrifugal impellers and diffusers; High speed motors and drives; and System integration of above technologies. Extensive design, development and testing efforts were carried out. Significant accomplishments achieved under this program are: (1) A total of 26 builds and over 200 tests were successfully completed with successively improved designs; (2) Use of foil gas bearings in refrigerant R134a was successfully proven; (3) A high speed, high power permanent magnet motor was developed; (4) An encoder was used for signal feedback between motor and controller. Due to temperature limitations of the encoder, the compressor could not operate at higher speed and in turn at higher pressure. In order to alleviate this problem a unique sensorless controller was developed; (5) This controller has successfully been tested as stand alone; however, it has not yet been integrated and tested as a system; (6) The compressor successfully operated at water cooled condensing temperatures Due to temperature limitations of the encoder, it could not be operated at air cooled condensing temperatures. (7) The two-stage impellers/diffusers worked well separately but combined did not match well.

  9. 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.

  10. Review on stress corrosion and corrosion fatigue failure of centrifugal compressor impeller

    NASA Astrophysics Data System (ADS)

    Sun, Jiao; Chen, Songying; Qu, Yanpeng; Li, Jianfeng

    2015-03-01

    Corrosion failure, especially stress corrosion cracking and corrosion fatigue, is the main cause of centrifugal compressor impeller failure. And it is concealed and destructive. This paper summarizes the main theories of stress corrosion cracking and corrosion fatigue and its latest developments, and it also points out that existing stress corrosion cracking theories can be reduced to the anodic dissolution (AD), the hydrogen-induced cracking (HIC), and the combined AD and HIC mechanisms. The corrosion behavior and the mechanism of corrosion fatigue in the crack propagation stage are similar to stress corrosion cracking. The effects of stress ratio, loading frequency, and corrosive medium on the corrosion fatigue crack propagation rate are analyzed and summarized. The corrosion behavior and the mechanism of stress corrosion cracking and corrosion fatigue in corrosive environments, which contain sulfide, chlorides, and carbonate, are analyzed. The working environments of the centrifugal compressor impeller show the behavior and the mechanism of stress corrosion cracking and corrosion fatigue in different corrosive environments. The current research methods for centrifugal compressor impeller corrosion failure are analyzed. Physical analysis, numerical simulation, and the fluid-structure interaction method play an increasingly important role in the research on impeller deformation and stress distribution caused by the joint action of aerodynamic load and centrifugal load.

  11. Radial loads and axial thrusts on centrifugal pumps

    SciTech Connect

    Not Available

    1986-01-01

    The proceedings of a seminar organised by the Power Industries Division of the IMechE are presented in this text. Complete contents: Review of parameters influencing hydraulic forces on centrifugal impellers; The effect of fluid forces at various operation conditions on the vibrations of vertical turbine pumps; A review of the pump rotor axial equilibrium problem - some case studies; Dynamic hydraulic loading on a centrifugal pump impeller; Experimental research on axial thrust loads of double suction centrifugal pumps; A comparison of pressure distribution and radial loads on centrifugal pumps; A theoretical and experimental investigation of axial thrusts within a multi-stage centrifugal pump.

  12. 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.

  13. Vibration analysis of large centrifugal pump rotors

    NASA Astrophysics Data System (ADS)

    Y Zhao, W.; Ge, J. G.; Ma, D.; Li, C. M.; Bao, S. B.

    2013-12-01

    Through the critical speed of centrifugal pumps, internal flow field and the force of the impeller, we analyze centrifugal pump vibration. Using finite element analysis software ANSYS to calculate the natural frequency of the rotor system and the critical speed; with the help of the Fluent software to simulate pump internal flow field, we conclude that speed increase will not cause intense vibration of the fluid in the pump. Using unsteady numerical simulation we discovered that in an impeller suffering transient radial force cyclical change periodically, as well as the frequency size determined by the product of the impeller speed and number of blades, resonance phenomena should make impeller to transient radial force frequency. If wanting to avoid pump resonance when it is running away, the transient radial force frequency should avoid the frequency range which can cause resonance.

  14. A vibration model for centrifugal contactors

    SciTech Connect

    Leonard, R.A.; Wasserman, M.O.; Wygmans, D.G.

    1992-11-01

    Using the transfer matrix method, we created the Excel worksheet ``Beam`` for analyzing vibrations in centrifugal contactors. With this worksheet, a user can calculate the first natural frequency of the motor/rotor system for a centrifugal contactor. We determined a typical value for the bearing stiffness (k{sub B}) of a motor after measuring the k{sub B} value for three different motors. The k{sub B} value is an important parameter in this model, but it is not normally available for motors. The assumptions that we made in creating the Beam worksheet were verified by comparing the calculated results with those from a VAX computer program, BEAM IV. The Beam worksheet was applied to several contactor designs for which we have experimental data and found to work well.

  15. 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.

  16. Rigorous buoyancy driven bubble mixing for centrifugal microfluidics.

    PubMed

    Burger, S; Schulz, M; von Stetten, F; Zengerle, R; Paust, N

    2016-01-01

    We present batch-mode mixing for centrifugal microfluidics operated at fixed rotational frequency. Gas is generated by the disk integrated decomposition of hydrogen peroxide (H2O2) to liquid water (H2O) and gaseous oxygen (O2) and inserted into a mixing chamber. There, bubbles are formed that ascent through the liquid in the artificial gravity field and lead to drag flow. Additionaly, strong buoyancy causes deformation and rupture of the gas bubbles and induces strong mixing flows in the liquids. Buoyancy driven bubble mixing is quantitatively compared to shake mode mixing, mixing by reciprocation and vortex mixing. To determine mixing efficiencies in a meaningful way, the different mixers are employed for mixing of a lysis reagent and human whole blood. Subsequently, DNA is extracted from the lysate and the amount of DNA recovered is taken as a measure for mixing efficiency. Relative to standard vortex mixing, DNA extraction based on buoyancy driven bubble mixing resulted in yields of 92 ± 8% (100 s mixing time) and 100 ± 8% (600 s) at 130g centrifugal acceleration. Shake mode mixing yields 96 ± 11% and is thus equal to buoyancy driven bubble mixing. An advantage of buoyancy driven bubble mixing is that it can be operated at fixed rotational frequency, however. The additional costs of implementing buoyancy driven bubble mixing are low since both the activation liquid and the catalyst are very low cost and no external means are required in the processing device. Furthermore, buoyancy driven bubble mixing can easily be integrated in a monolithic manner and is compatible to scalable manufacturing technologies such as injection moulding or thermoforming. We consider buoyancy driven bubble mixing an excellent alternative to shake mode mixing, in particular if the processing device is not capable of providing fast changes of rotational frequency or if the low average rotational frequency is challenging for the other integrated fluidic operations. PMID:26607320

  17. Operating and maintenance guidelines for screenbowl centrifuges

    SciTech Connect

    Jahnig, W.S.R.; Bratton, R.; Luttrell, G.

    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.

  18. Potential flow through centrifugal pumps and turbines

    NASA Technical Reports Server (NTRS)

    Sorensen, E

    1941-01-01

    The methods of conformal transformation up to the present have been applied to the potential flows in the rotation of solid bodies only to a limited extent. This report deals with aspects of centrifugal pumps and turbines such as: the complex potential for rotation, potential for the flow due to the blade rotation, velocities at the blade tip, comparison with "infinite number of blades," and a variable number of blades.

  19. 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.

  20. Operating comparison of absorption and centrifugal chillers

    SciTech Connect

    Tozer, R.M. South Bank Univ., London )

    1994-10-01

    Previous papers have dealt with the comparisons of absorption and centrifugal chillers and indicated the benefits of using absorption machines. Also, the ideal thermodynamic performances and limitations of absorption cycles have been derived. Nevertheless, the need to update this recent work is necessary for several reasons: utility company tariffs are under continuous review; large, double stage, direct-fired absorption chillers are being introduced into the market; and the CFCs are being phased out. The introduction of direct-fired absorption chillers into the United Kingdom (UK) market indicates that maintenance costs are cheaper than expected. The CFC issue has obliged the market to use alternative refrigerants for centrifugal chillers. For this study, centrifugal chillers using R-134a were considered instead of other refrigerants because of the present market trend, although the use of this refrigerant increases the costs of these types of chillers. A comparative study using R-123 could be considered, but is outside the scope of this present work. In addition, payback periods were calculated in this study for both low voltage and high voltage applications, for when low voltage or high voltage electricity is supplied to the building. The client has the option of installing high voltage substations and switchgear in the building to benefit from lower tariffs from the electric utility companies.

  1. Compact, Automated Centrifugal Slide-Staining System

    NASA Technical Reports Server (NTRS)

    Feeback, Daniel L.; Clarke, Mark S. F.

    2004-01-01

    The Directional Acceleration Vector-Driven Displacement of Fluids (DAVD-DOF) system, under development at the time of reporting the information for this article, would be a relatively compact, automated, centrifugally actuated system for staining blood smears and other microbiological samples on glass microscope slides in either a microgravitational or a normal Earth gravitational environment. The DAVD-DOF concept is a successor to the centrifuge-operated slide stainer (COSS) concept, which was reported in Slide-Staining System for Microgravity or Gravity (MSC-22949), NASA Tech Briefs, Vol. 25, No. 1 (January, 2001), page 64. The COSS includes reservoirs and a staining chamber that contains a microscope slide to which a biological sample is affixed. The staining chamber is sequentially filled with and drained of staining and related liquids from the reservoirs by use of a weighted plunger to force liquid from one reservoir to another at a constant level of hypergravity maintained in a standard swing-bucket centrifuge. In the DAVD-DOF system, a staining chamber containing a sample would also be sequentially filled and emptied, but with important differences. Instead of a simple microscope slide, one would use a special microscope slide on which would be fabricated a network of very small reservoirs and narrow channels connected to a staining chamber (see figure). Unlike in the COSS, displacement of liquid would be effected by use of the weight of the liquid itself, rather than the weight of a plunger.

  2. 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

  3. Avoid self-priming centrifugal pump

    SciTech Connect

    Reeves, G.G.

    1987-01-01

    The self-priming horizontal centrifugal pump becomes known to its operator either as a good pump or a bad pump. The latter is usually replaced by another type of pump, even though a properly specified self-priming centrifugal pump might have been a good choice. Use of the guidelines described in this article are intended to help in the purchase and installation of a good pump. Self-priming centrifugal pumps are used for removing liquids from below grade sumps or pits that may also contain solids, fibers and/or muck. Alternate pumps for this service include submersible pumps, vertical turbine pumps and positive displacement pumps. These alternate pumps do not pass solid particles as large as self-priming pumps do without damage. Positive displacement pumps are not normally cost-effective when pumping liquid at rates in excess of 500 gallons per minute in low-head applications. Vertical and submersible pumps must be removed when cleaning of the pump is required. Self-priming pumps are easily cleaned by opening the access plates without moving the pump; and they cost less than the other types.

  4. 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.

  5. 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.

  6. 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

  7. 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

  8. 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

  9. Theory versus experiment for the rotordynamic coefficients of labyrinth gas seals. II - A comparison to experiment

    NASA Technical Reports Server (NTRS)

    Childs, D. W.; Scharrer, J. K.

    1987-01-01

    An experimental test facility is used to measure the leakage and rotordynamic coefficients of teeth-on-rotor and teeth-on-stator labyrinth gas seals. The test results are presented along with the theoretically predicted values for the two seal configurations at three different radial clearances and shaft speeds to 16,000 cpm. The test results show that the theory accurately predicts the cross-coupled stiffness for both seal configurations and shows improvement in the prediction of the direct damping for the teeth-on-rotor seal. The theory fails to predict a decrease in the direct damping coefficient for an increase in the radial clearance for the teeth-on-stator seal.

  10. 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.

  11. Equilibrium gas-liquid-solid contact angle from density-functional theory

    E-print Network

    Pereira, Antonio

    2010-01-01

    We investigate the equilibrium of a fluid in contact with a solid boundary through a density-functional theory. Depending on the conditions, the fluid can be in one phase, gas or liquid, or two phases, while the wall induces an external field acting on the fluid particles. We first examine the case of a liquid film in contact with the wall. We construct bifurcation diagrams for the film thickness as a function of the chemical potential. At a specific value of the chemical potential, two equally stable films, a thin one and a thick one, can coexist. As saturation is approached, the thickness of the thick film tends to infinity. This allows the construction of a liquid-gas interface that forms a well defined contact angle with the wall.

  12. Centrifugal (centripetal) and Coriolis velocities and accelerations in spaces with affine connections and metrics as models of space-time

    E-print Network

    Sawa Manoff

    2003-09-09

    The notions of centrifugal (centripetal) and Coriolis velocities and accelerations are introduced and considered in spaces with affine connections and metrics used as models of space or of space-time. It is shown that these types of velocities and accelerations are generated by the relative motions between mass elements in a continuous media or of particles. The velocities and accelerations are closely related to the kinematic characteristics of the relative velocity and of the relative acceleration. The relation between the centrifugal (centripetal) velocity and the Hubble law is found. The centrifugal (centripetal) acceleration could be interpreted as gravitational acceleration as it has been done in the Einstein theory of gravitation. This fact could be used as a basis for working out of new gravitational theories in spaces with affine connections and metrics.

  13. Centrifugal (centripetal) and Coriolis velocities and accelerations in spaces with affine connections and metrics as models of space-time

    E-print Network

    Manoff, S

    2003-01-01

    The notions of centrifugal (centripetal) and Coriolis velocities and accelerations are introduced and considered in spaces with affine connections and metrics used as models of space or of space-time. It is shown that these types of velocities and accelerations are generated by the relative motions between mass elements in a continuous media or of particles. The velocities and accelerations are closely related to the kinematic characteristics of the relative velocity and of the relative acceleration. The relation between the centrifugal (centripetal) velocity and the Hubble law is found. The centrifugal (centripetal) acceleration could be interpreted as gravitational acceleration as it has been done in the Einstein theory of gravitation. This fact could be used as a basis for working out of new gravitational theories in spaces with affine connections and metrics.

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

    SciTech Connect

    Yasseri, S.; Rahnema, F.

    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)

  15. Developments in Stochastic Coupled Cluster Theory: The initiator approximation and application to the Uniform Electron Gas

    E-print Network

    Spencer, James S

    2015-01-01

    We describe further details of the Stochastic Coupled Cluster method and a diagnostic of such calculations, the shoulder height, akin to the plateau found in Full Configuration Interaction Quantum Monte Carlo. We describe an initiator modification to Stochastic Coupled Cluster Theory and show that initiator calculations can be extrapolated to the unbiased limit. We apply this method to the 3D 14-electron uniform electron gas and present complete basis set limit values of the CCSD and previously unattainable CCSDT correlation energies for up to rs = 2, showing a requirement to include triple excitations to accurately calculate energies at high densities.

  16. Bacterial Cell Surface Damage Due to Centrifugal Compaction

    PubMed Central

    Peterson, Brandon W.; van der Mei, Henny C.; Busscher, Henk J.

    2012-01-01

    Centrifugal damage has been known to alter bacterial cell surface properties and interior structures, including DNA. Very few studies exist on bacterial damage caused by centrifugation because of the difficulty in relating centrifugation speed and container geometry to the damage caused. Here, we provide a simple, versatile method of analysis for describing the compaction of bacteria during centrifugation based on a proposed centrifugation coefficient, C. Values of C can be related to different bacterial cell surface properties. Changing the geometry of the centrifugation container or centrifugation speeds changed the value of C significantly. Initial deposition rates of Staphylococcus aureus ATCC 12600 to a glass surface decayed exponentially from 4,217 to 1,478 cm?2 s?1 with increasing C, while the proportion of staphylococci with a zeta potential of around ?15 mV decreased from 97 to 58%. These surface-sensitive parameters were used independently to derive a critical centrifugation coefficient (0.040), above which centrifugation was considered to impact the outcome of surface-sensitive experiments due to cell surface damage. The critical centrifugation coefficient could successfully predict staphylococcal cell surface damage, i.e., a significant change in initial deposition rate or zeta potential distribution, in 84% of all cases included here, whereas the centrifugation speed could predict damage in only 58% of all cases. Moreover, controlling the centrifugation coefficient within narrow limits over a series of experiments yielded 43% smaller standard deviations in initial staphylococcal deposition rates than with centrifugation at fixed speeds for replicate experiments. PMID:22038609

  17. Flows and particles with centrifugal (centripetal) and Coriolis' accelerations in spaces with affine connections and metrics

    E-print Network

    Manoff, S

    2002-01-01

    The notions of centrifugal (centripetal) and Coriols' velocities and accelerations are introduced and considered in spaces with affine connections and metrics as velocities and accelerations of flows of mass elements (particles) moving in space-time. It is shown that these types of velocities and accelerations are generated by the relative motions between the mass elements. They are closely related to the kinematic characteristics of the relative velocity and the relative acceleration. The centrifugal (centripetal) acceleration could be interpreted as gravitational acceleration as it has been done in the Einstein theory of gravitation. This fact could be used as a basis for working out of new gravitational theories in spaces with affine connections and metrics.

  18. 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.

  19. Ultra scaledown to predict filtering centrifugation of secreted antibody fragments from fungal broth.

    PubMed

    Boulding, N; Yim, S S S; Keshavarz-Moore, E; Ayazi Shamlou, P; Berry, M

    2002-08-20

    Extracellularly expressed anti-hen egg lysozyme single-chain antibody fragments (scFv) produced by Aspergillus awamori were recovered using filtering centrifugation. Two filtering centrifuges with 0.5- and 30-L capacities were used to represent laboratory- and pilot-scale equipment, respectively. Critical regime analysis using the computational fluid dynamics (CFD) technique provided information about the local energy dissipation rates in both units. Experimental data indicated loss of scFv activity for energy dissipation rates above about 2.0 x 10(4) W kg(-1). This loss of activity increased in the presence of gas-liquid interfaces during filtering centrifugation. An ultra scaledown filtering centrifuge with a maximum working volume of 35 mL was designed to mimic the operating conditions identified by the critical regime analysis for the laboratory- and pilot-plant-scale units. The recovered scFv activity levels and the separation performance of the three units were comparable when operated at equal maximum energy dissipation rates. PMID:12115401

  20. Effect of fluid forces on rotor stability of centrifugal compressors and pumps

    NASA Technical Reports Server (NTRS)

    Colding-Jorgensen, J.

    1980-01-01

    A simple two dimensional model for calculating the rotordynamic effects of the impeller force in centrifugal compressors and pumps is presented. It is based on potential flow theory with singularities. Equivalent stiffness and damping coefficients are calculated for a machine with a vaneless volute formed as a logarithmic spiral. It is shown that for certain operating conditions, the impeller force has a destablizing effect on the rotor.

  1. 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.

    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.

  2. A Continuum Description of Rarefied Gas Dynamics (I)--- Derivation From Kinetic Theory

    E-print Network

    Xinzhong Chen; Hongling Rao; Edward A. Spiegel

    2001-05-20

    We describe an asymptotic procedure for deriving continuum equations from the kinetic theory of a simple gas. As in the works of Hilbert, of Chapman and of Enskog, we expand in the mean flight time of the constituent particles of the gas, but we do not adopt the Chapman-Enskog device of simplifying the formulae at each order by using results from previous orders. In this way, we are able to derive a new set of fluid dynamical equations from kinetic theory, as we illustrate here for the relaxation model for monatomic gases. We obtain a stress tensor that contains a dynamical pressure term (or bulk viscosity) that is process-dependent and our heat current depends on the gradients of both temperature and density. On account of these features, the equations apply to a greater range of Knudsen number (the ratio of mean free path to macroscopic scale) than do the Navier-Stokes equations, as we see in the accompanying paper. In the limit of vanishing Knudsen number, our equations reduce to the usual Navier-Stokes equations with no bulk viscosity.

  3. Oil-free centrifugal hydrogen compression technology demonstration

    SciTech Connect

    Heshmat, Hooshang

    2014-05-31

    One of the key elements in realizing a mature market for hydrogen vehicles is the deployment of a safe and efficient hydrogen production and delivery infrastructure on a scale that can compete economically with current fuels. The challenge, however, is that hydrogen, being the lightest and smallest of gases with a lower viscosity and density than natural gas, readily migrates through small spaces and is difficult to compresses efficiently. While efficient and cost effective compression technology is crucial to effective pipeline delivery of hydrogen, the compression methods used currently rely on oil lubricated positive displacement (PD) machines. PD compression technology is very costly, has poor reliability and durability, especially for components subjected to wear (e.g., valves, rider bands and piston rings) and contaminates hydrogen with lubricating fluid. Even so called “oil-free” machines use oil lubricants that migrate into and contaminate the gas path. Due to the poor reliability of PD compressors, current hydrogen producers often install duplicate units in order to maintain on-line times of 98-99%. Such machine redundancy adds substantially to system capital costs. As such, DOE deemed that low capital cost, reliable, efficient and oil-free advanced compressor technologies are needed. MiTi’s solution is a completely oil-free, multi-stage, high-speed, centrifugal compressor designed for flow capacity of 500,000 kg/day with a discharge pressure of 1200 psig. The design employs oil-free compliant foil bearings and seals to allow for very high operating speeds, totally contamination free operation, long life and reliability. This design meets the DOE’s performance targets and achieves an extremely aggressive, specific power metric of 0.48 kW-hr/kg and provides significant improvements in reliability/durability, energy efficiency, sealing and freedom from contamination. The multi-stage compressor system concept has been validated through full scale performance testing of a single stage with helium similitude gas at full speed in accordance with ASME PTC-10. The experimental results indicated that aerodynamic performance, with respect to compressor discharge pressure, flow, power and efficiency exceeded theoretical prediction. Dynamic testing of a simulated multistage centrifugal compressor was also completed under a parallel program to validate the integrity and viability of the system concept. The results give strong confidence in the feasibility of the multi-stage design for use in hydrogen gas transportation and delivery from production locations to point of use.

  4. 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.

  5. 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.

  6. Exercise protocols during short-radius centrifugation for artificial gravity

    E-print Network

    Edmonds, Jessica Leigh

    2008-01-01

    Long-duration spaceflight results in severe physiological deconditioning, threatening the success of interplanetary travel. Exercise combined with artificial gravity provided by centrifugation may be the comprehensive ...

  7. 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 ...

  8. Lube oil centrifuge saves Odeco $360,000/year

    SciTech Connect

    Closs, D.E.

    1983-05-01

    Purifying centrifuges were installed in the offshore drilling operation diesel engines of the Odeco Co. of New Orleans. The centrifuges extend filter life fourfold, eliminate the need to change oil at all, and defer the need for costly overhauls indefinitely. The Alfa-Laval built centrifuges were placed on 23 mobile rigs that Odeco has working in the Gulf of Mexico, and they paid for their cost twice over during the first year of operation. Originally, a lubricant centrifuge was tested aboard the Ocean Tempest. The results were so remarkable that similar installations were placed on all other vessels in the domestic drilling division.

  9. Development of a 3D circular microfluidic centrifuge for the separation of mixed particles by using their different centrifuge times

    NASA Astrophysics Data System (ADS)

    Jeon, H. J.; Kim, D. I.; Kim, M. J.; Nguyen, X. D.; Park, D. H.; Go, J. S.

    2015-11-01

    This paper presents a circular microfluidic centrifuge with two inlets and two outlets to separate mixed microparticles with a specially designed sample injection hole. To separate the mixed particles, it uses a rotational flow, generated in a chamber by counter primary flows in the microchannels. The shape and sizes of the circular microfluidic centrifuge have been designed through numerical evaluation to have a large relative centrifugal force. The difference of centrifuge times of the mixed particles of 1 ?m and 6 ?m was determined to be 8.2 s at an inlet Reynolds number of 500 and a sample Reynolds number of 20. In the experiment, this was measured to be about 10 s. From the separation of the two polymer particles analogous to the representative sizes of platelets and red blood cells, the circular microfluidic centrifuge shows a potential to separate human blood cells size-selectively by using the difference of centrifuge times.

  10. 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.

  11. Far-from-equilibrium gas kinetic theory: Reactive systems and sound propagation

    NASA Astrophysics Data System (ADS)

    Napier, Duncan George

    There exist many physical situations that involve large departures from thermodynamic equilibrium. These systems may be spatially nonuniform and/or time dependent. Traditional kinetic theory involves a perturbation type of approach that implies small departures from equilibrium. The present thesis is devoted to the development of theoretical methods valid for systems far removed from equilibrium. The techniques are applied to a study of the departure from equilibrium in reactive systems, and for the propagation of acoustic waves in gases. The rates of gas phase reactions can be calculated from averages of the appropriate reactive cross sections over the distribution of velocities of the reacting species. Reactive processes, especially for reactions with activation energy, tend to remove translationally energetic species and the velocity distribution is perturbed from a Maxwellian. The extent of the departure from a Maxwellian can be estimated from solutions of the Boltzmann equation. If there is a good separation of elastic and reactive time scales, steady solutions of the Boltzmann equation can be obtained with a procedure analogous to the Chapman-Enskog (CE) method. Nonequilibrium effects for model reactive systems with and without reverse reactions and in the presence and absence of products are studied. The range of validity of the CE method is studied by comparing results from a CE method and an explicitly time-dependent solution method. The CE approach assumes a weak perturbation and is referred to as a Weak Non-Equilibrium (WNE) approach. A Strong Non-Equilibrium (SNE) approach that treats the distribution functions of each of the components as Maxwellians at different temperatures is applied to strongly perturbed systems in which the reaction causes the temperatures of each species to differ from the system temperature. A third approach is a modification of the SNE approach and is referred to as Modified Strong Non-Equilibrium (MSNE). All three methods are compared with the results of an explicitly time-dependent solution. The CE method was found to be valid only when the ratio of elastic to reactive collision frequencies is greater than 105. The propagation of acoustic waves through a gas perturbs the velocity distribution function of the gas. In a collision-dominated gas, the velocity distribution function can be approximated by a Maxwellian and the phase velocity and attenuation of the sound wave can be determined from a dispersion relation derived from the Navier-Stokes equations of fluid dynamics. In the rarefied region, hydrodynamics is no longer valid and kinetic theory methods must be used. The method of solution of the Boltzmann equation by Wang-Chang and Uhlenbeck (WCU) fails to describe the behaviour of sound waves as the frequency of oscillation approaches that of the interparticle collisions in the gas. A generalized Boltzmann equation (GBE) introduced by Alexeev is applied to the sound problem and the results are compared with those of the WCU method and experiment. The kinetic theory description for sound propagation in a simple gas introduced by Sirovich and Thurber (ST) is applied to binary mixtures of gases and the results compared with those of experiment. It is shown that the ST method provides better agreement with experiment than the WCU method. The results with the GBE do not converge.

  12. 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.

  13. 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.

  14. Centrifugally Stimulated Exospheric Ion Escape at Mercury

    NASA Technical Reports Server (NTRS)

    Delcourt, Dominique; Seki, K.; Terada, N.; Moore, Thomas E.

    2012-01-01

    We investigate the transport of ions in the low-altitude magnetosphere magnetosphere of Mercury. We show that, because of small spatial scales, the centrifugal effect due to curvature of the E B drift paths can lead to significant particle energization in the parallel direction. We demonstrate that because of this effect, ions with initial speed smaller than the escape speed such as those produced via thermal desorption can overcome gravity and escape into the magnetosphere. The escape route of this low-energy exosphere originating material is largely controlled by the magnetospheric convection rate. This escape route spreads over a narrower range of altitudes when the convection rate increases. Bulk transport of low-energy planetary material thus occurs within a limited region of space once moderate magnetospheric convection is established. These results suggest that, via release of material otherwise gravitationally trapped, the E B related centrifugal acceleration is an important mechanism for the net supply of plasma to the magnetosphere of Mercury.

  15. Development of an implantable centrifugal blood pump.

    PubMed

    Goldstein, A H; Pacella, J J; Trumble, D R; Clark, R E

    1992-01-01

    The efficacy of centrifugal pumps for short-term (0-30 days) ventricular support has been widely reported and favorably compared with pulsatile systems. A small, durable, implantable centrifugal blood pump is being developed for medium-term use (up to 6 months). The pump is based on the Medtronic Hemadyne system that has existed in multiple forms over the past 30 years. The pump is approximately the size of a tennis ball, weighs 240 g, and is comprised of a 2.5 cm plastic impeller driven by a radially coupled brushless DC motor. In vitro hydraulic performance was recorded over a wide range of flow conditions on a mock circulatory loop. The pump generated 7 L/min flow against an afterload of 100 mmHg pressure, with a maximum power draw of 10.4 watts. Pulsatile flow was preserved when placed in conjunction with a simulated left ventricle. In vivo testing was performed in 10 healthy sheep for 10-292 hr. Heparin was used to facilitate cannulation, and no anticoagulation was administered after pump implantation. Blood chemistries reflecting hematologic, pulmonary, renal, and hepatic functions were recorded and demonstrated no adverse effects with normal pump operation. Complications were related to kinking of blood conduits and thrombus formation within the cannulae. These results are encouraging and warrant further studies to prove feasibility of this pump as a medium-term implantable ventricular assist device. PMID:1457882

  16. Centrifugal acceleration of the polar wind

    NASA Technical Reports Server (NTRS)

    Horwitz, J. L.; Ho, C. W.; Scarbro, H. D.; Wilson, G. R.; Moore, T. E.

    1994-01-01

    The effect of parallel ion acceleration associated with convection was first applied to energization of test particle polar ions by Cladis (1986). However, this effect is typically neglected in 'self-consistent' models of polar plasma outflow, apart from the fluid simulation by Swift (1990). Here we include approximations for this acceleration, which we broadly characterize as centrifugal in nature, in our time-dependent, semikinetic model of polar plasma outflow and describe the effects on the bulk parameter profiles and distribution functions of H+ and O+. For meridional convection across the pole the approximate parallel force along a polar magnetic field line may be written as F(sub cent, pole) = 1.5m(E(sub i))/B(sub i))squared (r(squared)/r(sup 3)(sub i)) where m is ion mass, r is geometric distance; and E(sub i), B(sub i) and r(sub i) refer to the electric and magnetic field magnitudes and geocentric distance at the ionosphere, respectively. For purely longitudinal convection along a constant L shell the parallel force is F(cent. long) = F(sub cent, pole)(1 - (r/(r(sub i)L))(sup 3/2)/(1 - 3r/(4 r(sub i)L))(sup 5/2). For high latitudes the difference between these two cases is relatively unimportant below approximately 5 R(sub E). We find that the steady state O+ bulk velocities and parallel temperatures strongly increase and decrease, respectively, with convection strength. In particular, the bulk velocities increase from near 0 km/s at 4000 km altitude to approximately 10 km/s at 5 R(sub E) geocentric distance for 50-mV/m ionospheric convection electric field. However, the centrifugal effect on the steady O+ density profiles depends on the exobase ion and electron temperatures: for low-base temperatures (T(sub i) = T(sub e) = 3000 K) the O+ density at high altitudes increases greatly with convection, while for higher base temperatures (T(sub i) = 5000 K, T(sub e) = 9000 K), the high-altitude O+ density decreases somewhat as convection is enhanced. The centrifugal force further has a pronounced effect on the escaping O+ flux, especially for cool exobase conditions; as referenced to the 4000-km altitude, the steady state O+ flux increases from 10(exp 5) ions/sq cm/s when the ionospheric convection field E(sub i) = 0 mV/m to approximately 10(exp 7) ions/sq cm/s when E(sub i) = 100 mV/m. The centrifugal effect also decreases the time scale for approach to steady-state. For example, in the plasma expansion for T(sub i) = T(sub e) = 3000 K, the O+ density at 7 R(sub E) reaches only 10(exp -7) of it final value approximately 1.5 hours after expansion onset for E(sub i) = 0. For meridional convection driven by E(sub i) = 50 mV/m, the density at the same time after initial injection is 30-50% of its asymptotic level. The centrifugal acceleration described here is a possible explanation for the large (up to approximately 10 km/s or more) o+ outflow velocities observed in the midlatitude polar magnetosphere with the Dynamics Explorer 1 and Akebono spacecraft.

  17. Gas-phase reactions of pd with acetone: A theoretical investigation using density functional theory

    NASA Astrophysics Data System (ADS)

    Dai, Guo-Liang; Wang, Chuan-Feng

    2012-12-01

    The gas-phase reaction of palladium atom with acetone is investigated using density functional theory. Geometries and energies of the reactants, intermediates, and products involved are calculated. Both ground and excited state potential energy surfaces are investigated in detail. The present results show that the title reaction start with the formation of an ?2-CH3COCH3-metal complex, followed by C-O, C-H, and C-C activation. These reactions can lead to four different products (PdO + C3H6, PdCH2COCH3 + H, PdCH2 + CH3CHO, and PdCOCH2 + CH4). The present results may be helpful in understanding the mechanism of the title reaction and further experimental investigation of the reaction.

  18. Kinetic theory analysis of rarefied gas flow through finite length slots

    NASA Technical Reports Server (NTRS)

    Raghuraman, P.; Willis, D. R.

    1977-01-01

    A kinetic-theory analysis is made of the flow of a rarefied monatomic gas through a two-dimensional slot connecting two reservoirs. Numerical solutions are obtained by the moment and discrete-ordinate methods. The former method portrays the transition-regime characteristics well but has limitations in the free-molecule regime. The latter method gives accurate results in the free-molecule and slip regimes and bolsters confidence in the accuracy of the transition-regime results. The numerical solution for the mass flux through the slot agrees well with an approximate analytical solution of the moment equations for length-to-width ratios from 6 to 0.5, pressure ratios from 0.8 to 0.1, and Knudsen numbers from 5 to 0.5.

  19. 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.

  20. 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.

  1. Spectral Functions of the Uniform Electron Gas via Coupled-Cluster Theory and Comparison to the $GW$ and Related Approximations

    E-print Network

    McClain, James; Watson, Thomas; Matthews, Devin A; Ronca, Enrico; Louie, Steven G; Berkelbach, Timothy C; Chan, Garnet Kin-Lic

    2015-01-01

    We use, for the first time, ab initio coupled-cluster theory to compute the spectral function of the uniform electron gas at a Wigner-Seitz radius of $r_\\mathrm{s}=4$. The coupled-cluster approximations we employ go significantly beyond the diagrammatic content of state-of-the-art $GW$ theory. We compare our calculations extensively to $GW$ and $GW$-plus-cumulant theory, illustrating the strengths and weaknesses of these methods in capturing the quasiparticle and satellite features of the electron gas. Our accurate calculations further allow us to address the long-standing debate over the occupied bandwidth of metallic sodium. Our findings indicate that the future application of coupled-cluster theory to condensed phase material spectra is highly promising.

  2. Experimental studies on the optimization design of a low specific speed centrifugal pump

    NASA Astrophysics Data System (ADS)

    Zhang, J. F.; Yuan, Y.; Yuan, S. Q.; Lu, W. G.; Yuan, J. P.

    2012-11-01

    Start your abstract here... For a low specific speed centrifugal pump with the requirement of high efficiency of 68% and non-overload power characteristics, series experimental studies, by matching 9 volutes with 19 impellers were done. By combining the former research results about the splitters and the non-overload theory in centrifugal pump, the theoretical conditions to achieve the property of non-overload in a centrifugal pump with splitters was analyzed, and formulas to estimate the maximum shaft power and its position are derived. Based on the requirement of high efficiency and non-overload, blade outlet angle ?2, blade outlet width b2, volute throat area Ft and the inlet diameter of splitters Di were chosen with three levels to design a normal L9 (34) orthogonal test scheme. Meanwhile, the optimized design scheme was determined, and corresponding test was done also, it demonstrates that the experiment purpose was reached, the design method to combine the splitters and non-overload theory is reasonable, which can get the property of high efficiency and non-overload.

  3. 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.

  4. 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

    ...for Subzone Status (Centrifugal and Submersible Pumps); Auburn, NY Pursuant...special-purpose subzone at the centrifugal and submersible pump manufacturing and warehousing...the manufacturing of centrifugal and submersible pumps and related...

  5. 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

  6. Coil planet centrifugation as a means for small particle separation

    NASA Technical Reports Server (NTRS)

    Herrmann, F. T.

    1983-01-01

    The coil planet centrifuge uses a centrifugal force field to provide separation of particles based on differences in sedimentation rates by flow through a rotating coiled tube. Three main separations are considered: (1) single phase fresh sheep and human erythrocytes, (2) single phase fixed heep and human erythrocytes, and (3) electrophoretically enhanced single phase fresh sheep and human erythrocytes.

  7. 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; laboratory tests; piles; sands. INTRODUCTION Centrifuges have been widely adopted in modelling geotechnical on both the random and the consistent variations which have been observed with CPTs in sand when identical

  8. Visualizing Unsteady Vortical Behavior of a Centrifugal Pump Mathias Otto

    E-print Network

    Visualizing Unsteady Vortical Behavior of a Centrifugal Pump Mathias Otto University of Magdeburg. The given data represents a high resolution simulation of a centrifugal pump used to transport liquids pump as a part of the IEEE Visualization Contest 2011. The given data set represents a high resolution

  9. Radial oscillation of a gas bubble in a fluid as a problem in canonical perturbation theory

    NASA Astrophysics Data System (ADS)

    Stephens, James

    2005-11-01

    The oscillation of a gas bubble is in a fluid is of interest in many areas of physics and technology. Lord Rayleigh treated the pressure developed in the collapse of cavitation bubbles and developed an expression for the collapse period. Minnaert developed a harmonic oscillator approximation to bubble oscillation in his study of the sound produced by running water. Oscillating bubbles are important to oceanographers studying the sound spectrum produced by water waves, geophysicists employing air guns as acoustic probes, mechanical engineers concerned with erosion of turbine blades, and military engineers concerned with the acoustic signatures developed by the propeller screws of ships and submarines. For the oceanographer, Minnaert's approximation is useful, for the latter two examples, Lord Rayleigh's analysis is appropriate. On the one hand, a bubble can be treated as a harmonic oscillator in the small amplitude regime, whereas even in the relatively moderate pressure regime characteristic of air guns the oscillation is strongly nonlinear and amplitude dependent. Is it possible to develop an analytic approximation that affords insight into the behavior of a bubble beyond the harmonic approximation of Minnaert? In this spirit, the free radial oscillation of a gas bubble in a fluid is treated as a problem in canonical perturbation theory. Several orders of the expansion are determined in order to explore the dependence of the oscillation frequency with bubble amplitude. The expansion to second order is inverted to express the time dependence of the oscillation.

  10. Density functional theory of gas-liquid phase separation in dilute binary mixtures

    E-print Network

    Ryuichi Okamoto; Akira Onuki

    2015-12-29

    We examine statics and dynamics of phase-separated states of dilute binary mixtures using density functional theory. In our systems, the difference in the salvation chemical potential $\\Delta\\mu_s$ between liquid and gas is considerably larger than the thermal energy $k_BT$ for each solute particle and the attractive interaction among the solute particles is weaker than that among the solvent particles. In these conditions, the saturated vapor pressure increases by an amount equal to the solute density in liquid multiplied by the large factor $k_BT \\exp(\\Delta\\mu_s/k_BT)$. As a result, phase separation is induced at low solute densities in liquid and the new phase remains in gaseous states, while the liquid pressure is outside the coexistence curve of the solvent. This explains the widely observed formation of stable nanobubbles in ambient water with a dissolved gas. We calculate the density and stress profiles across planar and spherical interfaces, where the surface tension decreases with increasing the interfacial solute adsorption. We realize stable solute-rich bubbles with radius about 30 nm, which minimize the free energy functional. We then study dynamics around such a bubble after a decompression of the surrounding liquid, where the bubble undergoes a damped oscillation. In addition, we present some exact and approximate expressions for the surface tension and the interfacial stress tensor.

  11. Lattice model theory of the equation of state covering the gas, liquid, and solid phases

    NASA Technical Reports Server (NTRS)

    Bonavito, N. L.; Tanaka, T.; Chan, E. M.; Horiguchi, T.; Foreman, J. C.

    1975-01-01

    The three stable states of matter and the corresponding phase transitions were obtained with a single model. Patterned after Lennard-Jones and Devonshires's theory, a simple cubic lattice model containing two fcc sublattices (alpha and beta) is adopted. The interatomic potential is taken to be the Lennard-Jones (6-12) potential. Employing the cluster variation method, the Weiss and the pair approximations on the lattice gas failed to give the correct phase diagrams. Hybrid approximations were devised to describe the lattice term in the free energy. A lattice vibration term corresponding to a free volume correction is included semi-phenomenologically. The combinations of the lattice part and the free volume part yield the three states and the proper phase diagrams. To determine the coexistence regions, the equalities of the pressure and Gibbs free energy per molecule of the coexisting phases were utilized. The ordered branch of the free energy gives rise to the solid phase while the disordered branch yields the gas and liquid phases. It is observed that the triple point and the critical point quantities, the phase diagrams and the coexistence regions plotted are in good agreement with the experimental values and graphs for argon.

  12. High Efficiency Centrifugal Compressor for Rotorcraft Applications

    NASA Technical Reports Server (NTRS)

    Medic, Gorazd; Sharma, Om P.; Jongwook, Joo; Hardin, Larry W.; McCormick, Duane C.; Cousins, William T.; Lurie, Elizabeth A.; Shabbir, Aamir; Holley, Brian M.; Van Slooten, Paul R.

    2014-01-01

    The report "High Efficiency Centrifugal Compressor for Rotorcraft Applications" documents the work conducted at UTRC under the NRA Contract NNC08CB03C, with cost share 2/3 NASA, and 1/3 UTRC, that has been extended to 4.5 years. The purpose of this effort was to identify key technical barriers to advancing the state-of-the-art of small centrifugal compressor stages; to delineate the measurements required to provide insight into the flow physics of the technical barriers; to design, fabricate, install, and test a state-of-the-art research compressor that is representative of the rear stage of an axial-centrifugal aero-engine; and to acquire detailed aerodynamic performance and research quality data to clarify flow physics and to establish detailed data sets for future application. The design activity centered on meeting the goal set outlined in the NASA solicitation-the design target was to increase efficiency at higher work factor, while also reducing the maximum diameter of the stage. To fit within the existing Small Engine Components Test Facility at NASA Glenn Research Center (GRC) and to facilitate component re-use, certain key design parameters were fixed by UTRC, including impeller tip diameter, impeller rotational speed, and impeller inlet hub and shroud radii. This report describes the design effort of the High Efficiency Centrifugal Compressor stage (HECC) and delineation of measurements, fabrication of the compressor, and the initial tests that were performed. A new High-Efficiency Centrifugal Compressor stage with a very challenging reduction in radius ratio was successfully designed, fabricated and installed at GRC. The testing was successful, with no mechanical problems and the running clearances were achieved without impeller rubs. Overall, measured pressure ratio of 4.68, work factor of 0.81, and at design exit corrected flow rate of 3 lbm/s met the target requirements. Polytropic efficiency of 85.5 percent and stall margin of 7.5 percent were measured at design flow rate and speed. The measured efficiency and stall margin were lower than pre-test CFD predictions by 2.4 percentage points (pt) and 4.5 pt, respectively. Initial impressions from the experimental data indicated that the loss in the efficiency and stall margin can be attributed to a design shortfall in the impeller. However, detailed investigation of experimental data and post-test CFD simulations of higher fidelity than pre-test CFD, and in particular the unsteady CFD simulations and the assessment with a wider range of turbulence models, have indicated that the loss in efficiency is most likely due to the impact of unfavorable unsteady impeller/diffuser interactions induced by diffuser vanes, an impeller/diffuser corrected flow-rate mismatch (and associated incidence levels), and, potentially, flow separation in the radial-to-axial bend. An experimental program with a vaneless diffuser is recommended to evaluate this observation. A subsequent redesign of the diffuser (and the radial-to-axial bend) is also recommended. The diffuser needs to be redesigned to eliminate the mismatching of the impeller and the diffuser, targeting a slightly higher flow capacity. Furthermore, diffuser vanes need to be adjusted to align the incidence angles, to optimize the splitter vane location (both radially and circumferentially), and to minimize the unsteady interactions with the impeller. The radial-to-axial bend needs to be redesigned to eliminate, or at least minimize, the flow separation at the inner wall, and its impact on the flow in the diffuser upstream. Lessons were also learned in terms of CFD methodology and the importance of unsteady CFD simulations for centrifugal compressors was highlighted. Inconsistencies in the implementation of a widely used two-equation turbulence model were identified and corrections are recommended. It was also observed that unsteady simulations for centrifugal compressors require significantly longer integration times than what is current practice in industry.

  13. Centrifugal regulator for control of deployment rates of deployable elements

    NASA Technical Reports Server (NTRS)

    Vermalle, J. C.

    1980-01-01

    The requirements, design, and performance of a centrifugal regulator aimed at limiting deployment rates of deployable elements are discussed. The overall mechanism is comprised of four distinct functional parts in a machined housing: (1) the centrifugal brake device, which checks the payout of a deployment cable; (2) the reducing gear, which produces the spin rate necesary for the braking device; (3) the payout device, which allows the unwinding of the cable; and (4) the locking device, which prevents untimely unwinding. The centrifugal regulator is set into operation by a threshold tension of the cable which unlocks the mechanism and allows unwinding. The pulley of the windout device drives the centrifugal brake with the help of the reducing gear. The centrifugal force pushes aside weights that produce friction of the studs in a cylindrical housing. The mechanism behaved well at qualification temperature and vibrations.

  14. Submersible electrically powered centrifugal and jet pump assembly

    SciTech Connect

    Erickson, J.W.; Petrie, H.L.

    1981-10-13

    A petroleum well has a plurality of centrifugal pump stages, a jet pump stage, and an electrical drive motor. A recirculated portion of the output from high pressure stages of the centrifugal pump provides power fluid for the jet pump, and the jet pump aspirates fluid from lower pressure centrifugal pump stages. The balance of the output of the high pressure stages goes to the surface as production. The output of the jet pump supplies the high pressure stages. A centrifugal cleaner upstream of the power fluid inlet for the jet pump cleans that stream of particulates. The overall flow rate through the centrifugal stages exceeds the production rate of the pump by the amount of power fluid for the jet pump. The jet pump caps the assembly and can be separately removed for servicing and adapting the pump to the flow requirements of the well.

  15. The development of the International Space Station centrifuge.

    PubMed

    Nakano, Tamotsu

    2004-11-01

    Gravitational biology research facility "Centrifuge" is currently under development for the International Space Station. Research in the Complex Organism Biology, indispensable to the progress in Health Science, is only possible in the Centrifuge aboard the station. So, on-orbit 1 G controls for various specimens including small mammals, fish, and higher plants will be rigorously done in the Centrifuge. This facility is also capable of providing "reduced gravity" likely on the Moon or on Mars. Thus, it will play a key role in creating knowledge of space fundamental biology. As part of the offset of NASA's Shuttle launch services for the Japanese Experiment Module, JAXA is developing the Centrifuge Rotor (CR), the Life Sciences Glovebox (LSG) and the Centrifuge Accommodation Module (CAM). Critical Design Review (CDR) of LSG was conducted on July 2004, while the system CDRs of the CAM and CR are scheduled for December 2004 and August 2005, respectively. Their launch schedules are under review. PMID:15858334

  16. Improved blood culture technique based on centrifugation: clinical evaluation.

    PubMed Central

    Dorn, G L; Land, G A; Wilson, G E

    1979-01-01

    A total of 3,335 blood samples from 1,180 patients suspected of having bacteremia were analyzed concurrently by two methods: (i) supplemented peptone broth with sodium polyanethanol sulfonate and a CO2 atmosphere; and (ii) lysis centrifugation at 3,000 X g for 30 min onto a high-density, hydrophobic cushion. The centrifugation technique recovered 80% of the positive cultures as compared with 67% for the broth method. The centrifugation technique showed an apparent increase in the isolation of staphylococcus aureus, Pseudomonas, and yeasts. In almost every instance, the time required for detection of a positive culture was shortest for the centrifugation method. Contamination rates for both systems were comparable (1.4%). Quantitation, offered only by the centrifugation method, proved useful on several occasions in discriminating between an opportunistic infection versus a skin contaminant and in judging efficacy of antimicrobial therapy. Images PMID:379034

  17. Reversible thermo-pneumatic valves on centrifugal microfluidic platforms.

    PubMed

    Aeinehvand, Mohammad Mahdi; Ibrahim, Fatimah; Harun, Sulaiman Wadi; Kazemzadeh, Amin; Rothan, Hussin A; Yusof, Rohana; Madou, Marc

    2015-08-21

    Centrifugal microfluidic systems utilize a conventional spindle motor to automate parallel biochemical assays on a single microfluidic disk. The integration of complex, sequential microfluidic procedures on these platforms relies on robust valving techniques that allow for the precise control and manipulation of fluid flow. The ability of valves to consistently return to their former conditions after each actuation plays a significant role in the real-time manipulation of fluidic operations. In this paper, we introduce an active valving technique that operates based on the deflection of a latex film with the potential for real-time flow manipulation in a wide range of operational spinning speeds. The reversible thermo-pneumatic valve (RTPV) seals or reopens an inlet when a trapped air volume is heated or cooled, respectively. The RTPV is a gas-impermeable valve composed of an air chamber enclosed by a latex membrane and a specially designed liquid transition chamber that enables the efficient usage of the applied thermal energy. Inputting thermo-pneumatic (TP) energy into the air chamber deflects the membrane into the liquid transition chamber against an inlet, sealing it and thus preventing fluid flow. From this point, a centrifugal pressure higher than the induced TP pressure in the air chamber reopens the fluid pathway. The behaviour of this newly introduced reversible valving system on a microfluidic disk is studied experimentally and theoretically over a range of rotational frequencies from 700 RPM to 2500 RPM. Furthermore, adding a physical component (e.g., a hemispherical rubber element) to induce initial flow resistance shifts the operational range of rotational frequencies of the RTPV to more than 6000 RPM. An analytical solution for the cooling of a heated RTPV on a spinning disk is also presented, which highlights the need for the future development of time-programmable RTPVs. Moreover, the reversibility and gas impermeability of the RTPV in the microfluidic networks are validated on a microfluidic disk designed for performing liquid circulation. Finally, an array of RTPVs is integrated into a microfluidic cartridge to enable sequential aliquoting for the conversion of dengue virus RNA to cDNA and the preparation of PCR reaction mixtures. PMID:26158597

  18. A modeling study of a centrifugal compressor

    SciTech Connect

    Popovic, P.; Shapiro, H.N.

    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.

  19. Algorithm for Controlling a Centrifugal Compressor

    NASA Technical Reports Server (NTRS)

    Benedict, Scott M.

    2004-01-01

    An algorithm has been developed for controlling a centrifugal compressor that serves as the prime mover in a heatpump system. Experimental studies have shown that the operating conditions for maximum compressor efficiency are close to the boundary beyond which surge occurs. Compressor surge is a destructive condition in which there are instantaneous reversals of flow associated with a high outlet-to-inlet pressure differential. For a given cooling load, the algorithm sets the compressor speed at the lowest possible value while adjusting the inlet guide vane angle and diffuser vane angle to maximize efficiency, subject to an overriding requirement to prevent surge. The onset of surge is detected via the onset of oscillations of the electric current supplied to the compressor motor, associated with surge-induced oscillations of the torque exerted by and on the compressor rotor. The algorithm can be implemented in any of several computer languages.

  20. 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.

  1. [Hemodynamic analysis of a centrifugal blood pump].

    PubMed

    Wang, Yang; Yang, Ming; Xu, Zihao; Zhuang, Xiaoqi; Li, Qilei; Xu, Liang

    2015-01-01

    This paper built the mathematical model of a centrifugal blood pump, which was designed by ourselves, combined it with that of the human cardiovascular system and simulated the coupling system using Matlab. Then we set up the experiment platform, linked the blood pump to mock human cardiovascular system in case of three-stage heart failure, and measured aortic pressure and flow under different speed. The comparison between experiment results and simulation results not only indicates the coupling model is correct and the blood pump works well, but also shows that with the increase of blood pump speed, the pulsation of aortic pressure and flow will be reduced, this situation will affect the structure and function of blood vessels. PMID:26027287

  2. Cavitation in transiently operating centrifugal pumps

    SciTech Connect

    Lefebvre, P.J.; Barker, W.P.

    1994-12-31

    The effect of transient operation on a centrifugal pump`s cavitation performance was investigated experimentally in the Naval Undersea Warfare Center`s Impeller Test Facility. For low facility pressures where cavitation occurred, its inception and desinence during the transient were determined by acoustic and visualization methods whose results agreed closely with predicted values based on quasi-steady analysis. The minimum facility pressure for cavitation-free operation also correlated well with quasi-steady predictions. Impeller suction performance continuously degraded (i.e., reduced suction pressure) as facility pressure was lowered from the minimum non-cavitating pressure and as the severity of cavitation increased. This degradation was actually a redistribution of pressure across the impeller since the total head rise was unaffected. The appearance of suction pressure degradation can be used as an alternate means of determining the minimum facility pressure for cavitation-free operation.

  3. 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.

  4. 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

  5. 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

  6. Water balance in rats exposed to chronic centrifugation.

    PubMed

    Ortiz, R M; Wade, C E

    2000-07-01

    Changes in gravitational load have been shown to alter renal function, which could potentially affect water balance. Therefore, the present study was conducted to determine the effects of chronic centrifugation on water balance. Eight Sprague-Dawley rats were centrifuged (12 days at 2 G), and eight rats were used as a control group. Water balance over the course of the study was determined by quantifying the percentage (%) of total body water [TBW; (TBW/body mass)] and water flux (water consumption - urine volume). TBW was estimated, by means of deuterium oxide dilution, before the study and after 3 days of centrifugation and by means of desiccation after 12 days of centrifugation. %TBW did not change in the centrifuged rats from initial levels or relative to controls over the course of the study. Differences between the sum of water consumption and sum of urine volume for the 12-day period were the same in both groups. Although an initial period of negative water balance was observed, the lack of a change in %TBW among the three measurement periods or in water flux over the 12 days of centrifugation suggests that water balance is not negatively affected as a result of centrifugation at 2 G. PMID:10904035

  7. Radial oscillation of a gas bubble in a fluid as a problem in canonical perturbation theory

    NASA Astrophysics Data System (ADS)

    Stephens, James

    2006-11-01

    The oscillation of a gas bubble is in a fluid is of interest in many areas of physics and technology. Lord Rayleigh treated the pressure developed in the collapse of cavitation bubbles and developed an expression for the collapse period. Minnaert developed a harmonic oscillator approximation to bubble oscillation in his study of the sound produced by running water. Besides recent interest in bubble oscillation in connection to sonoluminescence, an understanding of oscillating bubbles is of important to oceanographers studying the sound spectrum produced by water waves, geophysicists employing air guns as acoustic probes, mechanical engineers concerned with erosion of turbine blades, and military engineers concerned with the acoustic signatures developed by the propeller screws of ships and submarines. For the oceanographer, Minnaert's approximation is useful, for the latter two examples, Lord Rayleigh's analysis is appropriate. For the case of the airgun, a period of twice Rayleigh's period for the ``total collapse'' of the cavitation bubble is often cited as a good approximation for the period of an air bubble ejected from an air gun port, typically at ˜2000 psi), however for the geophysical example, numerical integration is employed from the outset to determine the dynamics of the bubble and the emitted acoustic energy. On the one hand, a bubble can be treated as a harmonic oscillator in the small amplitude regime, whereas even in the relatively moderate pressure regime characteristic of air guns the oscillation is strongly nonlinear and amplitude dependent. Is it possible to develop an analytic approximation that affords insight into the behavior of a bubble beyond the harmonic approximation of Minnaert? In this spirit, the free radial oscillation of a gas bubble in a fluid is treated as a problem in canonical perturbation theory. Several orders of the expansion are determined in order to explore the dependence of the oscillation frequency with bubble amplitude. The expansion to second order is inverted to express the time dependence of the oscillation.

  8. Centrifugal Casting Features/Metallurgical Characterization of Aluminum Alloys

    SciTech Connect

    Chirita, G.; Soares, D.; Cruz, D.; Silva, F. S.; Stefanescu, I.

    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)

  9. 27. RW Meyer Sugar Mill: 18761889. Centrifugals, 1879, 1881. Manufacturer, ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    27. RW Meyer Sugar Mill: 1876-1889. Centrifugals, 1879, 1881. Manufacturer, Unknown. Supplied by Honolulu Ironworks, Honolulu Hawaii, 1879, 1881. View: Historical view, 1934, from T.T. Waterman collection, Hawaiian Sugar Planters' Association. With the inner basket of the centrifugal revolving at 1200 rpm molasses flew outward from the granulated sugar, through the holes in the brass lining, and into the stationary outer basket. The molasses drained through the spout at the right and into molasses storage pits below the floor. The centrifugals were underdriven with a belt connected to the pulley beneath the basket. - R. W. Meyer Sugar Mill, State Route 47, Kualapuu, Maui County, HI

  10. Centrifugal Size-Separation Sieve for Granular Materials

    NASA Technical Reports Server (NTRS)

    Walton, Otis (Inventor); Dreyer, Christopher (Inventor); Riedel, Edward (Inventor)

    2015-01-01

    A centrifugal sieve and method utilizes centrifugal force in rapidly-rotated cylindrical or conical screens as the primary body force contributing to size segregation. Within the centrifugal acceleration field, vibration and/or shearing flows are induced to facilitate size segregation and eventual separation of the fines from the coarse material. Inside a rotating cylindrical or conical screen, a separately-rotated screw auger blade can be used to transport material along the rotating cylinder or conical wall and to induce shearing in the material.

  11. Ocular counterrolling induced by centrifugation during orbital space flight.

    PubMed

    Moore, S T; Clément, G; Raphan, T; Cohen, B

    2001-04-01

    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. PMID:11355379

  12. 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.

  13. Transition to Centrifugal Particle Motion in Rotating Drums

    E-print Network

    Gerald H. Ristow

    1998-08-04

    The dynamics and the transition to the centrifugal regime are studied analytically and numerically for particles in rotating drum. The importance of the particle-wall friction coefficient is demonstrated by studying first the motion of one non-rotating particle where three different regimes are found in the transition to the centrifugal motion. When a few rotating particles are considered, they behave similarly to one non-rotating particle in the low friction limit. A critical particle number is necessary to reach the centrifugal regime for which an analytic expression is derived in the limit of negligible inter-particle friction.

  14. Increased mitogenic response in lymphocytes from chronically centrifuged mice

    NASA Technical Reports Server (NTRS)

    Mueller, Otfried; Hunzinger, E.; Cogoli, Augusto; Bechler, B.; Lee, J.; Moore, J.; Duke, J.

    1990-01-01

    The effects upon the mitogenic response of splenic lymphocytes when exposing mice to prolonged hypergravity conditions (3.5 G for 1 year) were studied. Cultures of splenic lymphocytes isolated from both centrifuged and control (1 G) animals were stimulated with Concanavalin A and the response measured using both morphological and biochemical means. Lymphocytes obtained from centrifuged mice exhibited much higher activation rates (as measured by the incorporation of H-3 thymidine) and larger cell aggregates consisting of more lymphoblasts and mitotic figures than those observed in non centrifuged control animals. Isolated splenic lymphocytes thus appear to have been conditioned by hypergravity state.

  15. 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.

  16. Centrifugal distortion and the ring puckering vibration in the microwave spectrum of 2,3-dihydrofuran

    NASA Astrophysics Data System (ADS)

    Cervellati, R.; Degli Esposti, A.; Lister, D. G.; Lopez, J. C.; Alonso, J. L.

    1986-10-01

    The microwave spectrum of 2,3-dihydrofuran has been reinvestigated and measurements for the ground and first five excited states of the ring puckering vibration have been extended to higher frequencies and rotational quantum numbers in order to study the vibrational dependence of the rotational and centrifugal distortion constants. The ring puckering potential function derived by Green from the far infrared spectrum does not reproduce the vibrational dependence of the rotational constants well. A slightly different potential function is derived which gives a reasonable fit both to the far infrared spectrum and the rotational constants. This changes the barrier to ring inversion from 1.00 kJ mol -1 to 1.12 kJ mol -1. The vibrational dependence of the centrifugal distortion constants is accounted for satisfactorily by the theory developed by Creswell and Mills. An attempt to reproduce the vibrational dependence of the rotational and centrifugal distortion constants using the ring puckering potential function and a simple model for this vibration has very limited success.

  17. Centrifugal compressor modifications and their effect on high-frequency pipe wall vibration

    SciTech Connect

    Motriuk, R.W.; Harvey, D.P.

    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.

  18. 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.

  19. Sample of CFD optimization of a centrifugal compressor stage

    NASA Astrophysics Data System (ADS)

    Galerkin, Y.; Drozdov, A.

    2015-08-01

    Industrial centrifugal compressor stage is a complicated object for gas dynamic design when the goal is to achieve maximum efficiency. The Authors analyzed results of CFD performance modeling (NUMECA Fine Turbo calculations). Performance prediction in a whole was modest or poor in all known cases. Maximum efficiency prediction was quite satisfactory to the contrary. Flow structure in stator elements was in a good agreement with known data. The intermediate type stage “3D impeller + vaneless diffuser+ return channel” was designed with principles well proven for stages with 2D impellers. CFD calculations of vaneless diffuser candidates demonstrated flow separation in VLD with constant width. The candidate with symmetrically tampered inlet part b3 / b2 = 0,73 appeared to be the best. Flow separation takes place in the crossover with standard configuration. The alternative variant was developed and numerically tested. The obtained experience was formulated as corrected design recommendations. Several candidates of the impeller were compared by maximum efficiency of the stage. The variant with gas dynamic standard principles of blade cascade design appeared to be the best. Quasi - 3D non-viscid calculations were applied to optimize blade velocity diagrams - non-incidence inlet, control of the diffusion factor and of average blade load. “Geometric” principle of blade formation with linear change of blade angles along its length appeared to be less effective. Candidates’ with different geometry parameters were designed by 6th math model version and compared. The candidate with optimal parameters - number of blades, inlet diameter and leading edge meridian position - is 1% more effective than the stage of the initial design.

  20. Isolation and retrieval of circulating tumor cells using centrifugal forces

    E-print Network

    Hou, Han Wei

    Presence and frequency of rare circulating tumor cells (CTCs) in bloodstreams of cancer patients are pivotal to early cancer detection and treatment monitoring. Here, we use a spiral microchannel with inherent centrifugal ...

  1. Impeller loss reduction in multi-stage centrifugal compressors

    E-print Network

    Barile, Kristina (Kristina Marie)

    2015-01-01

    Loss generation features for the first stage impeller in a multistage centrifugal compressor are examined using three-dimensional RANS computations. The calculations were carried out for a baseline configuration and for ...

  2. 16. View northwest of Arctic Chamber Worthington centrifugal compressor and ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    16. View northwest of Arctic Chamber Worthington centrifugal compressor and control panel, in machine area. - Natick Research & Development Laboratories, Climatic Chambers Building, U.S. Army Natick Research, Development & Engineering Center (NRDEC), Natick, Middlesex County, MA

  3. Centrifugally spun starch-based fibers from amylopectin rich starches.

    PubMed

    Li, Xianglong; Chen, Huanhuan; Yang, Bin

    2016-02-10

    Centrifugal spinning and electrospinning have proved to be effective techniques for fabricating micro-to-nanofibers. However, starches of amylopectin content above 65% cannot be fabricated to fiber by electrospinning. This paper is focus on the centrifugal spinnability of amylopectin rich starches. We investigated the amylopectin content of starches by Dual-wavelength colorimetry, studied the rheological properties of starch dopes to determine entanglement concentration (ce) by rotary rheometer. Results indicated that amylopectin rich native corn and potato starches, which with amylopectin content higher than 65%, were suitable for centrifugal spinning to micro-to-nanofibers. Additionally, starch-based fibers were successfully fabricated from the amylose rich corn starch as well. Rheological studies showed that the entanglement concentration (ce) of starch solution was crucial for successful centrifugal spinning. PMID:26686151

  4. 14. CENTRIFUGAL FREQUENCY RELAY IN WAYSIDE CABINET, NEW HAVEN YARD ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    14. CENTRIFUGAL FREQUENCY RELAY IN WAYSIDE CABINET, NEW HAVEN YARD - New York, New Haven & Hartford Railroad, Automatic Signalization System, Long Island Sound shoreline between Stamford & New Haven, Stamford, Fairfield County, CT

  5. 15. FRONT VIEW, DETAIL, CENTRIFUGAL FREQUENCY RELAY IN WAYSIDE CABINET, ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    15. FRONT VIEW, DETAIL, CENTRIFUGAL FREQUENCY RELAY IN WAYSIDE CABINET, NEW HAVEN YARD - New York, New Haven & Hartford Railroad, Automatic Signalization System, Long Island Sound shoreline between Stamford & New Haven, Stamford, Fairfield County, CT

  6. Looking Southeast at Precipitation System, Steam Dryer and Centrifuge in ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Looking Southeast at Precipitation System, Steam Dryer and Centrifuge in Red Room within Recycle Recovery Building - Hematite Fuel Fabrication Facility, Recycle Recovery Building, 3300 State Road P, Festus, Jefferson County, MO

  7. 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

  8. 2. View of centrifugal pump house sitting at edge of ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    2. View of centrifugal pump house sitting at edge of drainage canal, looking E. - Laurel Valley Sugar Plantation, Drainage Plant, 2 Miles South of Thibodaux on State Route 308, Thibodaux, Lafourche Parish, LA

  9. 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

  10. 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 ...

  11. Squat exercise biomechanics during short-radius centrifugation

    E-print Network

    Duda, Kevin R., 1979-

    2007-01-01

    Artificial gravity (AG) created by short-radius centrifugation is a promising countermeasure to the physiological de-conditioning that results from long-duration spaceflight. However, as on Earth, gravity alone does not ...

  12. Forced response predictions in modern centrifugal compressor design

    E-print Network

    Smythe, Caitlin J. (Caitlin Jeanne)

    2005-01-01

    A computational interrogation of the time-averaged and time-unsteady flow fields of two centrifugal compressors of nearly identical design (the enhanced, which encountered aeromechanical difficulty, and production, which ...

  13. 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

  14. 18. View north of Tropic Chamber Worthington centrifugal compressor and ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    18. View north of Tropic Chamber Worthington centrifugal compressor and control panel, in machine area. - Natick Research & Development Laboratories, Climatic Chambers Building, U.S. Army Natick Research, Development & Engineering Center (NRDEC), Natick, Middlesex County, MA

  15. 19. LOWER OIL ROOM DIABLO POWERHOUSE: SHARPLES OIL CENTRIFUGE AND ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    19. LOWER OIL ROOM DIABLO POWERHOUSE: SHARPLES OIL CENTRIFUGE AND OIL TANK, 1989. - Skagit Power Development, Diablo Powerhouse, On Skagit River, 6.1 miles upstream from Newhalem, Newhalem, Whatcom County, WA

  16. Centrifugally-assisted combustion synthesis of functionally-graded materials

    SciTech Connect

    Lai, W.; Munir, Z.A.; McCoy, B.J.; Risbud, S.H.

    1997-02-01

    Functionally graded materials (FGM`s) have been prepared by a variety of techniques, including combustion synthesis, and the use of a centrifugal force in this method of synthesis has been demonstrated previously. However, in the earlier work, a centrifugal force was applied to investigate the changes in the dynamics of self-propagating combustion waves or to deposit coatings on the inside surfaces of pipes. The use of a centrifugal force to investigate the formation of FGM`s has not been reported previously and is the focus of this communication. In this work, the authors have chosen thermite reactions to investigate the feasibility of FGM formation by centrifugally-assisted combustion synthesis.

  17. 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 ...

  18. Multi-parameter control for centrifugal compressor performance optimization

    E-print Network

    Mannai, Sébastien (Sébastien Karim)

    2014-01-01

    The potential performance benefit of actuating inlet guide vane (IGV) angle, variable diffuser vane (VDV) angle and impeller speed to implement a multi-parameter control on a centrifugal compressor system is assessed. The ...

  19. TECHNOLOGY EVALUATION REPORT: RETECH'S PLASMA CENTRIFUGAL FURNACE - VOLUME I

    EPA Science Inventory

    A demonstration of the Retech, Inc. Plasma Centrifugal Furnace (PCF) was conducted under the Superfund Innovative Technology Evaluation (SITE) Program at the Department of Energy's (DOE's) Component Development and Integration Facility in Butte, Montana. The furnace uses heat gen...

  20. 25. RW Meyer Sugar Mill: 18761889. Centrifugals, 1879, 1881. Manufacturer, ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    25. RW Meyer Sugar Mill: 1876-1889. Centrifugals, 1879, 1881. Manufacturer, Unknown. Supplied by Honolulu Iron Works, Honolulu, Hawaii, 1879, 1881. View: After sugar was granulated and cooled it had to be dried and drained, completely separating the sugar crystals from the molasses. Revolving at 1200 rpm the inner basket drove the molasses outward into the stationary outer basket leaving dried sugar behind. The steam engine counter-shaft at the left was belt driven and belts running from the counter-shaft pulleys to the centrifugals' base-pulleys provided the necessary power. Part of the clutch system which moved the belt from a moving to a stationary pulley, thus turning the centrifugals on and off, is seen in Between the counter-shaft and the centrifugals. - R. W. Meyer Sugar Mill, State Route 47, Kualapuu, Maui County, HI

  1. 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. ...

  2. Wave Augmented Diffuser for Centrifugal Compressor

    NASA Technical Reports Server (NTRS)

    Skoch, Gary J. (Inventor); Paxson, Daniel E. (Inventor)

    2001-01-01

    A wave augmented diffuser for a centrifugal compressor surrounds the outlet of an impeller that rotates on a drive shaft having an axis of rotation. The impeller brings flow in in an axial direction and imparts kinetic energy to the flow discharging it in radial and tangential directions. The flow is discharged into a plurality of circumferentially disposed wave chambers. The wave chambers are periodically opened and closed by a rotary valve such that the flow through the diffuser is unsteady. The valve includes a plurality of valve openings that are periodically brought into and out of fluid communication with the wave chambers. When the wave chambers are closed, a reflected compression wave moves upstream towards the diffuser bringing the flow into the wave chamber to rest. This action recovers the kinetic energy from the flow and limits any boundary layer growth. The flow is then discharged in an axial direction through an opening in the valve plate when the valve plate is rotated to an open position. The diffuser thus efficiently raises the static pressure of the fluid and discharges an axially directed flow at a radius that is predominantly below the maximum radius of the diffuser.

  3. High efficiency, variable geometry, centrifugal cryogenic pump

    SciTech Connect

    Forsha, M.D.; Nichols, K.E.; Beale, C.A.

    1994-12-31

    A centrifugal cryogenic pump has been developed which has a basic design that is rugged and reliable with variable speed and variable geometry features that achieve high pump efficiency over a wide range of head-flow conditions. The pump uses a sealless design and rolling element bearings to achieve high reliability and the ruggedness to withstand liquid-vapor slugging. The pump can meet a wide range of variable head, off-design flow requirements and maintain design point efficiency by adjusting the pump speed. The pump also has features that allow the impeller and diffuser blade heights to be adjusted. The adjustable height blades were intended to enhance the pump efficiency when it is operating at constant head, off-design flow rates. For small pumps, the adjustable height blades are not recommended. For larger pumps, they could provide off-design efficiency improvements. This pump was developed for supercritical helium service, but the design is well suited to any cryogenic application where high efficiency is required over a wide range of head-flow conditions.

  4. Flow characteristics of a centrifugal pump

    SciTech Connect

    Liu, C.H.; Vafidis, C.; Whitelaw, J.H. . Dept. of Mechanical Engineering)

    1994-06-01

    Measurements of velocity have been obtained in a centrifugal pump in terms of angle-resolved values in the impeller passages, the volute, the inlet and exit ducts and are presented in absolute and relative frames. The pump comprised a radial flow impeller with four backswept blades and a single volute, and the working liquid had the same refractive index as the transparent casing to facilitate the use of a laser-Doppler velocimeter. The flows in the impeller passages wee found to depart from the curvature of the blade surfaces at off-design conditions with separation from the suction surface and from the shroud. Secondary flows from the suction to pressure surfaces were dominated by the influences of the relative motion between the shroud and impeller surfaces and the tip leakage. Geometric differences of 0.5 mm and one degree in spacing of the four blades caused differences in passage velocity of up to 6 percent at the lowest discharge. The flowrate from each impeller passage varied with volute circumferential position by up to 25 percent at an off-design flowrate. Poor matching of the impeller and volute at off-design conditions caused swirl and separation in the inlet and exit pipes.

  5. Centrifugal governor for internal combustion engines

    SciTech Connect

    Ohkoshi, M.

    1987-04-14

    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 cam pivotable about and relative to a fulcrum shaft thereof and having a cam surface including a cam surface portion determining a fuel increment to be applied at the start of the engine; a sensor lever having one end engaged by the control rack; the sensor lever having another end disposed to engage with the cam surface portion of the torque cam when the engine is in a starting condition, to permit displacement of the control rack into a fuel increasing position for the start of the engine; and a cancelling spring interposed between the torque cam and the tension lever and urging the torque cam with a force dependent upon the angularity of the tension lever to cause pivoting of the torque cam about the fulcrum shaft thereof in a direction of disengaging the sensor lever from the cam surface portion of the torque cam. The improvement is described comprising biasing means for forcibly pivotally displacing, immediately before operation of a starter of the engine, the torque cam in one direction against the urging force of the cancelling spring to a predetermined position.

  6. Centrifugal governor for internal combustion engines

    SciTech Connect

    Ohnishi, M.

    1986-08-12

    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 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 disposed for engagement with the cam surface of the torque cam, the sensor lever being adapted to engage with the cam surface of the torque cam when the engine is in a starting condition, to cause displacement of the control rack into a fuel increasing position for the start of the engine; and spring means interposed between the torque cam and the tension lever and urging the torque cam with a force dependent upon the angularity of the tension lever in a direction of disengaging the sensor lever from the cam surface of the torque cam; the spring means comprising first and second springs, one of the first and second springs being formed of a thermosensitive material having a smaller spring constant at a low temperature below a predetermined value, and a larger spring constant at a temperature above the predetermined value; and the first and second springs of the spring means comprising coiled springs disposed concentrically with each other.

  7. Investigation of Flow in a Centrifugal Pump

    NASA Technical Reports Server (NTRS)

    Fischer, Karl

    1946-01-01

    The investigation of the flow in a centrifugal pump indicated that the flow patterns in frictional fluid are fundamentally different from those in frictionless fluid. In particular, the dead air space adhering to the section side undoubtedly causes a reduction of the theoretically possible delivery head. The velocity distribution over a parallel circle is also subjected to a noticeable change as a result of the incomplete filling of the passages. The relative velocity on the pressure side of the vane, which for passages completely filled with active flow would differ little from zero even at comparatively lower than normal delivery volume, is increased, so that no rapid reverse flow occurs on the pressure side of the vane even for smaller delivery volume. It was established, further, that the flow ceases to be stationary for very small quantities of water. The inflow to the impeller can be regarded as radial for the operating range an question. The velocity triangles at the exit are subjected to a significant alteration in shape ae a result of the increased peripheral velocity, which may be of particular importance in the determination of the guide vane entrance angle.

  8. Centrifugal microfluidic platforms: advanced unit operations and applications.

    PubMed

    Strohmeier, O; Keller, M; Schwemmer, F; Zehnle, S; Mark, D; von Stetten, F; Zengerle, R; Paust, N

    2015-10-01

    Centrifugal microfluidics has evolved into a mature technology. Several major diagnostic companies either have products on the market or are currently evaluating centrifugal microfluidics for product development. The fields of application are widespread and include clinical chemistry, immunodiagnostics and protein analysis, cell handling, molecular diagnostics, as well as food, water, and soil analysis. Nevertheless, new fluidic functions and applications that expand the possibilities of centrifugal microfluidics are being introduced at a high pace. In this review, we first present an up-to-date comprehensive overview of centrifugal microfluidic unit operations. Then, we introduce the term "process chain" to review how these unit operations can be combined for the automation of laboratory workflows. Such aggregation of basic functionalities enables efficient fluidic design at a higher level of integration. Furthermore, we analyze how novel, ground-breaking unit operations may foster the integration of more complex applications. Among these are the storage of pneumatic energy to realize complex switching sequences or to pump liquids radially inward, as well as the complete pre-storage and release of reagents. In this context, centrifugal microfluidics provides major advantages over other microfluidic actuation principles: the pulse-free inertial liquid propulsion provided by centrifugal microfluidics allows for closed fluidic systems that are free of any interfaces to external pumps. Processed volumes are easily scalable from nanoliters to milliliters. Volume forces can be adjusted by rotation and thus, even for very small volumes, surface forces may easily be overcome in the centrifugal gravity field which enables the efficient separation of nanoliter volumes from channels, chambers or sensor matrixes as well as the removal of any disturbing bubbles. In summary, centrifugal microfluidics takes advantage of a comprehensive set of fluidic unit operations such as liquid transport, metering, mixing and valving. The available unit operations cover the entire range of automated liquid handling requirements and enable efficient miniaturization, parallelization, and integration of assays. PMID:26035697

  9. 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.

  10. Investigation of centrifugal pump performance under two-phase flow conditions

    SciTech Connect

    Noghrehkar, G.R.; Kawaji, M.; Chan, A.M.C.; Nakamura, H.; Kukita, Y.

    1995-03-01

    A one-dimensional two-fluid model has been used to study the centrifugal pump head degradation phenomena and to analyze the gas-liquid interaction within the pump impeller under high pressure, steam-water two-phase flow conditions. The analytical model was used to predict the two-phase pump head data for the small-scale and full-scale nuclear reactor pumps and the predictions of the head degradation compared favorably with the test data for different suction void fractions. The physical mechanisms responsible for head degradation were also investigated.

  11. 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.

  12. Theory versus experiment for the rotordynamic coefficients of annular gas seals. II - Constant-clearance and convergent-tapered geometry

    NASA Technical Reports Server (NTRS)

    Nelson, C. C.; Childs, D. W.; Nicks, C.; Elrod, D.

    1985-01-01

    The leakage and rotordynamic coefficients of constant-clearance and convergent-tapered annular gas seals were measured in an experimental test facility. The results are presented along with the theoretically predicted values. Of particular interest is the prediction that optimally tapered seals have significantly larger direct stiffness than straight seals. The experimental results verify this prediction. Generally the theory does quite well, but fails to predict the large increase in direct stiffness when the fluid is pre-rotated.

  13. Theory versus experiment for the rotordynamic coefficients of annular gas seals. Part 2: Constant clearance and convergent-tapered geometry

    NASA Technical Reports Server (NTRS)

    Nelson, C. C.; Childs, D. W.; Nicks, C.; Elrod, D.

    1985-01-01

    The leakage and rotordynamic coefficients of constant-clearance and convergent-tapered annular gas seals were measured in an experimental test facility. The results are presented along with the theoretically predicted values. Of particular interest is the prediction that optimally tapered seals have significantly larger direct siffness than straight seals. The experimental results verify this prediction. Generally the theory does quite well, but fails to predict the large increase in direct stiffness when the fluid is pre-rotated.

  14. Cerebral Hypoperfusion Precedes Nausea During Centrifugation

    NASA Technical Reports Server (NTRS)

    Serrador, Jorge M.; Schlegel, Todd T.; Black, F. Owen; Wood, Scott J.

    2004-01-01

    Nausea and motion sickness are important operational concerns for aviators and astronauts. Understanding underlying mechanisms associated with motion sickness may lead to new treatments. The goal of this work was to determine if cerebral blood flow changes precede the development of nausea in motion sick susceptible subjects. Cerebral flow velocity in the middle cerebral artery (transcranial Doppler), blood pressure (Finapres) and end-tidal CO2 were measured while subjects were rotated on a centrifuge (250 degrees/sec). Following 5 min of rotation, subjects were translated 0.504 m off-center, creating a +lGx centripetal acceleration in the nasal-occipital plane. Ten subjects completed the protocol without symptoms while 5 developed nausea (4 while 6ff-center and 1 while rotating on-center). Prior to nausea, subjects had significant increases in blood pressure (+13plus or minus 3 mmHg, P less than 0.05) and cerebrovascular resistance (+46 plus or minus 17%, P less than 0.05) and decreases in cerebral flow velocity both in the second (-13 plus or minus 4%) and last minute (-22 plus or minus 5%) before symptoms (P less than 0.05). In comparison, controls demonstrated no change in blood pressure or cerebrovascular resistance in the last minute of off-center rotation and only a 7 plus or minus 2% decrease in cerebral flow velocity. All subjects had significant hypocapnia (-3.8 plus or minus 0.4 mmHg, P less than 0.05), however this hypocapnia could not fully explain the cerebral hypoperfusion associated with the development of nausea. These data indicate that reductions in cerebral blood flow precede the development of nausea. Further work is necessary to determine what role cerebral hypoperfusion plays in motion sickness and whether cerebral hypoperfusion can be used to predict the development of nausea in susceptible individuals.

  15. 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

  16. Single stage high pressure centrifugal slurry pump

    DOEpatents

    Meyer, John W. (Palo Alto, CA); Bonin, John H. (Sunnyvale, CA); Daniel, Arnold D. (Alameda, CA)

    1984-03-27

    Apparatus is shown for feeding a slurry to a pressurized housing. An impeller that includes radial passages is mounted in the loose fitting housing. The impeller hub is connected to a drive means and a slurry supply means which extends through the housing. Pressured gas is fed into the housing for substantially enveloping the impeller in a bubble of gas.

  17. Single stage high pressure centrifugal slurry pump

    SciTech Connect

    Meyer, J.W.; Bonin, J.H.; Daniel, A.D.

    1984-03-27

    Apparatus is shown for feeding a slurry to a pressurized housing. An impeller that includes radial passages is mounted in the loose fitting housing. The impeller hub is connected to a drive means and a slurry supply means which extends through the housing. Pressured gas is fed into the housing for substantially enveloping the impeller in a bubble of gas. 9 figs.

  18. Relocation and repair of the National Geotechnical Centrifuge. Final report

    SciTech Connect

    Cheney, J.A.

    1994-10-01

    In January of 1984, the large geotechnical centrifuge located at NASA Ames Research Center, was in the first stages of operational checkout when the main thrust bearing of the large D.C. drive motor failed. After many months of investigation and proposals for repair of the facility, it became evident that it would be far more advantageous to the engineering community to remove those components of the centrifuge that were undamaged to the Davis campus and replace the drive system completely. The large centrifuge had cost over 2 million dollars to build, and it would have been irresponsible to simply scrap it. Recognizing this fact, funds were solicited and received from various sources, and Beam Engineering Inc. was contracted to design and construct the centrifuge at its new location. The University of California contributed a quarter of a million dollars and Tyndall Air Force Base, through Los Alamos National Laboratory, contributed $140,000. There were funds also contributed by LANL, LLNL, US Navy and NSF. The first stage in the phased development of the newly located centrifuge is nearing completion, which prompts the writing of this report. By the time that this report reaches the reader the first runs of the centrifuge will have been completed. The present report describes the present capability of the centrifuge and the plans for upgrading as time goes on. Several pilot studies were carried out. The experiments involved (1) the effects of nearby explosions on buried thin walled containers and (2) the advection and dispersion of toxic waste water through soils.

  19. Active stabilization to prevent surge in centrifugal compression systems

    NASA Technical Reports Server (NTRS)

    Epstein, Alan H.; Greitzer, Edward M.; Simon, Jon S.; Valavani, Lena

    1993-01-01

    This report documents an experimental and analytical study of the active stabilization of surge in a centrifugal engine. The aims of the research were to extend the operating range of a compressor as far as possible and to establish the theoretical framework for the active stabilization of surge from both an aerodynamic stability and a control theoretic perspective. In particular, much attention was paid to understanding the physical limitations of active stabilization and how they are influenced by control system design parameters. Previously developed linear models of actively stabilized compressors were extended to include such nonlinear phenomena as bounded actuation, bandwidth limits, and robustness criteria. This model was then used to systematically quantify the influence of sensor-actuator selection on system performance. Five different actuation schemes were considered along with four different sensors. Sensor-actuator choice was shown to have a profound effect on the performance of the stabilized compressor. The optimum choice was not unique, but rather shown to be a strong function of some of the non-dimensional parameters which characterize the compression system dynamics. Specifically, the utility of the concepts were shown to depend on the system compliance to inertia ratio ('B' parameter) and the local slope of the compressor speedline. In general, the most effective arrangements are ones in which the actuator is most closely coupled to the compressor, such as a close-coupled bleed valve inlet jet, rather than elsewhere in the flow train, such as a fuel flow modulator. The analytical model was used to explore the influence of control system bandwidth on control effectiveness. The relevant reference frequency was shown to be the compression system's Helmholtz frequency rather than the surge frequency. The analysis shows that control bandwidths of three to ten times the Helmholtz frequency are required for larger increases in the compressor flow range. This has important implications for implementation in gas turbine engines since the Helmholtz frequencies can be over 100 Hz, making actuator design extremely challenging.

  20. Optimizing Natural Gas Networks through Dynamic Manifold Theory and a Decentralized Algorithm: Belgium Case Study

    NASA Astrophysics Data System (ADS)

    Koch, Caleb; Winfrey, Leigh

    2014-10-01

    Natural Gas is a major energy source in Europe, yet political instabilities have the potential to disrupt access and supply. Energy resilience is an increasingly essential construct and begins with transmission network design. This study proposes a new way of thinking about modelling natural gas flow. Rather than relying on classical economic models, this problem is cast into a time-dependent Hamiltonian dynamics discussion. Traditional Natural Gas constraints, including inelastic demand and maximum/minimum pipe flows, are portrayed as energy functions and built into the dynamics of each pipe flow. Doing so allows the constraints to be built into the dynamics of each pipeline. As time progresses in the model, natural gas flow rates find the minimum energy, thus the optimal gas flow rates. The most important result of this study is using dynamical principles to ensure the output of natural gas at demand nodes remains constant, which is important for country to country natural gas transmission. Another important step in this study is building the dynamics of each flow in a decentralized algorithm format. Decentralized regulation has solved congestion problems for internet data flow, traffic flow, epidemiology, and as demonstrated in this study can solve the problem of Natural Gas congestion. A mathematical description is provided for how decentralized regulation leads to globally optimized network flow. Furthermore, the dynamical principles and decentralized algorithm are applied to a case study of the Fluxys Belgium Natural Gas Network.

  1. Centrifugation Effects on Estrous Cycling, Mating Success and Pregnancy Outcome in Rats

    NASA Technical Reports Server (NTRS)

    Ronca, April E.; Rushing, Linda S.; Tou, Janet; Wade, Charles E.; Baer, Lisa A.

    2005-01-01

    We analyzed the effects of 2-g centrifugation on estrous cycling, mating success and pregnancy outcome in rats. Sexually mature female and male rats were assigned to either 2-g centrifuge or non-centrifuge conditions, and to non-breeding or breeding conditions. In non-breeding females, estrous cycles were analyzed by examining vaginal cytology before and for 35 days during centrifugation. Breeding females were time-mated following 7 days of adaptation to centrifugation. Following adaptation to centrifugation, estrous cycle duration over a five-cycle period was similar in centrifuged and non-centrifuged females. Identical numbers of centrifuged and non-centrifuged females conceived, however centrifuged females took four-times longer than controls to achieve conception. Births occurred at the normal gestational length. Pup birth weight and postnatal survival were p<0.05 reduced in centrifuged as compared to non-centrifuged groups. In conclusion, 2-g centrifugation had no effect on estrous cycle length or the probably of becoming pregnant but delayed conception and diminished pregnancy outcome.

  2. [The analytical setting of rotary speed of centrifuge rotor and centrifugation time in chemical, biochemical and microbiological practice].

    PubMed

    Zolotarev, K V

    2012-08-01

    The researchers happen to face with suspensions in their chemical, biochemical and microbiological practice. The suspensions are the disperse systems with solid dispersed phase and liquid dispersion medium and with dispersed phase particle size > 100 nm (10-7 m). Quite often the necessity occurs to separate solid particles from liquid. To use for this purpose the precipitation in gravitation field can make the process to progress too long. In this respect an effective mode is the precipitation in the field of centrifugal forces--the centrifugation. The rotary speed of centrifuge rotor and centrifugation time can be set analytically using regularities of general dynamics and hydrodynamics. To this effect, should be written and transformed the equation of First and Second Newton Laws for suspension particle being in the field of centrifugal forces and forces of resistance of liquid and vessel wall. The force of liquid resistance depends on particle motion condition in liquid. To determine the regimen the Archimedes and Reynolds numerical dimensionless criteria are to be applied. The article demonstrates the results of these transformations as analytical inverse ratio dependence of centrifugation time from rotary speed. The calculation of series of "rate-time" data permits to choose the optimal data pair on the assumption of centrifuge capacity and practical reasonability. The results of calculations are validated by actual experimental data hence the physical mathematical apparatus can be considered as effective one. The setting progress depends both from parameter (Reynolds criterion) and data series calculation. So, the most convenient way to apply this operation is the programming approach. The article proposes to use the program Microsoft Excel and VBA programming language for this purpose. The possibility to download the file from Internet to use it for fast solution is proposed. PMID:23097986

  3. A fuzzy controlled three-phase centrifuge for waste separation

    SciTech Connect

    Parkinson, W.J.; Smith, R.E.; Miller, N.

    1998-02-01

    The three-phase centrifuge technology discussed in this paper was developed by Neal Miller, president of Centech, Inc. The three-phase centrifuge is an excellent device for cleaning up oil field and refinery wastes which are typically composed of hydrocarbons, water, and solids. The technology is unique. It turns the waste into salable oil, reusable water, and landfill-able solids. No secondary waste is produced. The problem is that only the inventor can set up and run the equipment well enough to provide an optimal cleanup. Demand for this device has far exceeded a one man operation. There is now a need for several centrifuges to be operated at different locations at the same time. This has produced a demand for an intelligent control system, one that could replace a highly skilled operator, or at least supplement the skills of a less experienced operator. The control problem is ideally suited to fuzzy logic, since the centrifuge is a highly complicated machine operated entirely by the skill and experience of the operator. A fuzzy control system was designed for and used with the centrifuge.

  4. Development of a Feeder for Uninterrupted Centrifugation Studies

    NASA Technical Reports Server (NTRS)

    Mulenburg, Gerald M.; Vasques, Marilyn F.; Gundo, Daniel P.; Griffith, Jon B.; Wade, Charles E. (Technical Monitor)

    1994-01-01

    A specialized paste diet feeder was developed in support of a hypergravity (2G) centrifuge study. The centrifuge study was to be compared to a previously flown Russian Cosmos spaceflight so experimental parameters of the 14 day spaceflight had to be duplicated. In order to duplicate at hyper G an experiment that took place in weightlessness, all other conditions must be as identical as possible. Stopping the centrifuge to provide maintenance for the animals causes unacceptable changes in experimental research results. Thus the experimental protocol required the delivery of a designated amount of paste diet at regular intervals for a two week period without stopping the centrifuge. A centrifuge and a stationary control cage, each containing 10 laboratory rats, were fitted with feeders that were calibrated to provide 140 plus or minus 2g of paste diet every 6 hours. This paper describes development of the feeder design and results of its operation over the two week experiment. The design philosophy and details of the feeder system are provided with recommendations for future such devices.

  5. Dynamic mean field theory for lattice gas models of fluids confined in porous materials: Higher order theory based on the Bethe-Peierls and path probability method approximations

    SciTech Connect

    Edison, John R.; Monson, Peter A.

    2014-07-14

    Recently we have developed a dynamic mean field theory (DMFT) for lattice gas models of fluids in porous materials [P. A. Monson, J. Chem. Phys. 128(8), 084701 (2008)]. The theory can be used to describe the relaxation processes in the approach to equilibrium or metastable states for fluids in pores and is especially useful for studying system exhibiting adsorption/desorption hysteresis. In this paper we discuss the extension of the theory to higher order by means of the path probability method (PPM) of Kikuchi and co-workers. We show that this leads to a treatment of the dynamics that is consistent with thermodynamics coming from the Bethe-Peierls or Quasi-Chemical approximation for the equilibrium or metastable equilibrium states of the lattice model. We compare the results from the PPM with those from DMFT and from dynamic Monte Carlo simulations. We find that the predictions from PPM are qualitatively similar to those from DMFT but give somewhat improved quantitative accuracy, in part due to the superior treatment of the underlying thermodynamics. This comes at the cost of greater computational expense associated with the larger number of equations that must be solved.

  6. Stationary patterns in centrifugally driven interfacial elastic fingering.

    PubMed

    Carvalho, Gabriel D; Gadêlha, Hermes; Miranda, José A

    2014-12-01

    A vortex sheet formalism is used to search for equilibrium shapes in the centrifugally driven interfacial elastic fingering problem. We study the development of interfacial instabilities when a viscous fluid surrounded by another of smaller density flows in the confined environment of a rotating Hele-Shaw cell. The peculiarity of the situation is associated to the fact that, due to a chemical reaction, the two-fluid boundary becomes an elastic layer. The interplay between centrifugal and elastic forces leads to the formation of a rich variety of stationary shapes. Visually striking equilibrium morphologies are obtained from the numerical solution of a nonlinear differential equation for the interface curvature (the shape equation), determined by a zero vorticity condition. Classification of the various families of shapes is made via two dimensionless parameters: an effective bending rigidity (ratio of elastic to centrifugal effects) and a geometrical radius of gyration. PMID:25615189

  7. Design Optimization of a Centrifugal Fan with Splitter Blades

    NASA Astrophysics Data System (ADS)

    Heo, Man-Woong; Kim, Jin-Hyuk; Kim, Kwang-Yong

    2015-05-01

    Multi-objective optimization of a centrifugal fan with additionally installed splitter blades was performed to simultaneously maximize the efficiency and pressure rise using three-dimensional Reynolds-averaged Navier-Stokes equations and hybrid multi-objective evolutionary algorithm. Two design variables defining the location of splitter, and the height ratio between inlet and outlet of impeller were selected for the optimization. In addition, the aerodynamic characteristics of the centrifugal fan were investigated with the variation of design variables in the design space. Latin hypercube sampling was used to select the training points, and response surface approximation models were constructed as surrogate models of the objective functions. With the optimization, both the efficiency and pressure rise of the centrifugal fan with splitter blades were improved considerably compared to the reference model.

  8. Centrifuge Techniques and Apparatus for Transport Experiments in Porous Media

    SciTech Connect

    Earl D. Mattson; Carl D. Paler; Robert W. Smith; Markus Flury

    2010-06-01

    This paper describes experimental approaches and apparatus that we have developed to study solute and colloid transport in porous media using Idaho National Laboratory's 2-m radius centrifuge. The ex-perimental techniques include water flux scaling with applied acceleration at the top of the column and sub-atmospheric pressure control at the column base, automation of data collection, and remote experimental con-trol over the internet. These apparatus include a constant displacement piston pump, a custom designed liquid fraction collector based on switching valve technology, and modified moisture monitoring equipment. Suc-cessful development of these experimental techniques and equipment is illustrated through application to transport of a conservative tracer through unsaturated sand column, with centrifugal acceleration up to 40 gs. Development of such experimental equipment that can withstand high accelerations enhances the centrifuge technique to conduct highly controlled unsaturated solute/colloid transport experiments and allows in-flight liquid sample collection of the effluent.

  9. Cause of kinematic differences during centrifugal and centripetal saccades.

    PubMed

    Koene, Ansgar R; Erkelens, Casper J

    2002-06-01

    Measurements of eye movements have shown that centrifugal movements (i.e. away from the primary position) have a lower maximum velocity and a longer duration than centripetal movements (i.e. toward the primary position) of the same size. In 1988 Pelisson proposed that these kinematic differences might be caused by differences in the neural command signals, oculomotor mechanics or a combination of the two. By using the result of muscle force measurements that were made in recent years (Orbit 1.8 Gaze mechanics simulation, Eidactics, San Francisco, 1999) we simulated the muscle forces during centrifugal and centripetal saccades. Based on these simulations we show that the cause of the kinematic differences between the centrifugal and centripetal saccades is the non-linear force-velocity relationship (i.e. muscle viscosity) of the muscles. PMID:12127111

  10. Parametric performance evaluation of a hydraulic centrifugal pump

    NASA Astrophysics Data System (ADS)

    Heo, M. W.; Y Kim, K.; Ma, S. B.; Yoo, I. S.; Choi, W. C.; Kim, J. H.; Choi, Y. S.

    2014-03-01

    Parametric study of a hydraulic centrifugal pump with backward curved blades has been performed numerically using three-dimensional Reynolds-averaged Navier-Stokes equations. The shear stress transport turbulence model was used for analysis of turbulence. The finite volume method and an unstructured grid system were used for the numerical solution. The optimal grid system in the computational domain was selected through a grid dependency test. Tested parameters were related to the geometry of the impeller and volute: seven variables defining the hub and shroud contours and the blades angle of impeller, and two variables defining the inlet width and expansion angle of volute. The effects of these parameters on the hydrodynamic performance of the centrifugal pump have been investigated. It was found that the centrifugal water pump with the twisted blades has the enhancing efficiency compared to the straight blades pump.

  11. Centrifugally activated bearing for high-speed rotating machinery

    DOEpatents

    Post, R.F.

    1994-02-15

    A centrifugally activated bearing is disclosed. The bearing includes an annular member that extends laterally and radially from a central axis. A rotating member that rotates about the central axis relative to the annular member is also included. The rotating member has an interior chamber that surrounds the central axis and in which the annular member is suspended. Furthermore, the interior chamber has a concave shape for retaining a lubricant therein while the rotating member is at rest and for retaining a lubricant therein while the rotating member is rotating. The concave shape is such that while the rotating member is rotating a centrifugal force causes a lubricant to be forced away from the central axis to form a cylindrical surface having an axis collinear with the central axis. This centrifugally displaced lubricant provides restoring forces to counteract lateral displacement during operation. 4 figures.

  12. Biohazards Assessment in Large-Scale Zonal Centrifugation

    PubMed Central

    Baldwin, C. L.; Lemp, J. F.; Barbeito, M. S.

    1975-01-01

    A study was conducted to determine the biohazards associated with use of the large-scale zonal centrifuge for purification of moderate risk oncogenic viruses. To safely and conveniently assess the hazard, coliphage T3 was substituted for the virus in a typical processing procedure performed in a National Cancer Institute contract laboratory. Risk of personnel exposure was found to be minimal during optimal operation but definite potential for virus release from a number of centrifuge components during mechanical malfunction was shown by assay of surface, liquid, and air samples collected during the processing. High concentration of phage was detected in the turbine air exhaust and the seal coolant system when faulty seals were employed. The simulant virus was also found on both centrifuge chamber interior and rotor surfaces. Images PMID:1124921

  13. Solvent-free cleaning using a centrifugal cryogenic pellet accelerator

    SciTech Connect

    Haines, J.R.; Fisher, P.W.; Foster, C.A.

    1995-06-01

    An advanced centrifuge that accelerates frozen CO{sub 2} pellets to high speeds for surface cleaning and paint removal is being developed at the Oak Ridge National Laboratory. The centrifuge-based accelerator was designed, fabricated, and tested under a program sponsored by the Warner Robins Air Logistics Center, Robins Air Force Base, Georgia. In comparison to the more conventional compressed air ``sandblast`` pellet accelerators, the centrifugal accelerator system can achieve higher pellet speeds, has precise speed control, and is more than ten times as energy efficient. Furthermore, the use of frozen CO{sub 2} pellets instead of conventional metal, plastic, sand, or other abrasive materials that remain solid at room temperature, minimizes the waste stream. This apparatus has been used to demonstrate cleaning of various surfaces, including removal of paint, oxide coatings, metal coatings, organic coatings, and oil and grease coatings from a variety of surfaces. The design and operation of the apparatus is discussed.

  14. Space Station Centrifuge: A Requirement for Life Science Research

    NASA Technical Reports Server (NTRS)

    Smith, Arthur H.; Fuller, Charles A.; Johnson, Catherine C.; Winget, Charles M.

    1992-01-01

    A centrifuge with the largest diameter that can be accommodated on Space Station Freedom is required to conduct life science research in the microgravity environment of space. (This was one of the findings of a group of life scientists convened at the University of California, Davis, by Ames Research Center.) The centrifuge will be used as a research tool to understand how gravity affects biological processes; to provide an on-orbit one-g control; and to assess the efficacy of using artificial gravity to counteract the deleterious biological effect of space flight. The rationale for the recommendation and examples of using ground-based centrifugation for animal and plant acceleration studies are presented. Included are four appendixes and an extensive bibliography of hypergravity studies.

  15. Centrifugally activated bearing for high-speed rotating machinery

    DOEpatents

    Post, Richard F. (Walnut Creek, CA)

    1994-01-01

    A centrifugally activated bearing is disclosed. The bearing includes an annular member that extends laterally and radially from a central axis. A rotating member that rotates about the central axis relative to the annular member is also included. The rotating member has an interior chamber that surrounds the central axis and in which the annular member is suspended. Furthermore, the interior chamber has a concave shape for retaining a lubricant therein while the rotating member is at rest and for retaining a lubricant therein while the rotating member is rotating. The concave shape is such that while the rotating member is rotating a centrifugal force causes a lubricant to be forced away from the central axis to form a cylindrical surface having an axis collinear with the central axis. This centrifugally displaced lubricant provides restoring forces to counteract lateral displacement during operation.

  16. Passively Shunted Piezoelectric Damping of Centrifugally-Loaded Plates

    NASA Technical Reports Server (NTRS)

    Duffy, Kirsten P.; Provenza, Andrew J.; Trudell, Jeffrey J.; Min, James B.

    2009-01-01

    Researchers at NASA Glenn Research Center have been investigating shunted piezoelectric circuits as potential damping treatments for turbomachinery rotor blades. This effort seeks to determine the effects of centrifugal loading on passively-shunted piezoelectric - damped plates. Passive shunt circuit parameters are optimized for the plate's third bending mode. Tests are performed both non-spinning and in the Dynamic Spin Facility to verify the analysis, and to determine the effectiveness of the damping under centrifugal loading. Results show that a resistive shunt circuit will reduce resonant vibration for this configuration. However, a tuned shunt circuit will be required to achieve the desired damping level. The analysis and testing address several issues with passive shunt circuit implementation in a rotating system, including piezoelectric material integrity under centrifugal loading, shunt circuit implementation, and tip mode damping.

  17. Stationary patterns in centrifugally driven interfacial elastic fingering

    NASA Astrophysics Data System (ADS)

    Carvalho, Gabriel D.; Gadêlha, Hermes; Miranda, José A.

    2014-12-01

    A vortex sheet formalism is used to search for equilibrium shapes in the centrifugally driven interfacial elastic fingering problem. We study the development of interfacial instabilities when a viscous fluid surrounded by another of smaller density flows in the confined environment of a rotating Hele-Shaw cell. The peculiarity of the situation is associated to the fact that, due to a chemical reaction, the two-fluid boundary becomes an elastic layer. The interplay between centrifugal and elastic forces leads to the formation of a rich variety of stationary shapes. Visually striking equilibrium morphologies are obtained from the numerical solution of a nonlinear differential equation for the interface curvature (the shape equation), determined by a zero vorticity condition. Classification of the various families of shapes is made via two dimensionless parameters: an effective bending rigidity (ratio of elastic to centrifugal effects) and a geometrical radius of gyration.

  18. 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; Bi, Hong-Mei; Shi, Ke-Ying

    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.

  19. Secondary Containment Design for a High Speed Centrifuge

    SciTech Connect

    Snyder, K.W.

    1999-03-01

    Secondary containment for high speed rotating machinery, such as a centrifuge, is extremely important for operating personnel safety. Containment techniques can be very costly, ungainly and time consuming to construct. A novel containment concept is introduced which is fabricated out of modular sections of polycarbonate glazed into a Unistrut metal frame. A containment study for a high speed centrifuge is performed which includes the development of parameters for secondary containment design. The Unistrut/polycarbonate shield framing concept is presented including design details and proof testing procedures. The economical fabrication and modularity of the design indicates a usefulness for this shielding system in a wide variety of containment scenarios.

  20. Isolation of Early and Late Endosomes by Density Gradient Centrifugation.

    PubMed

    de Araújo, Mariana E G; Lamberti, Giorgia; Huber, Lukas A

    2015-01-01

    Density gradient centrifugation is a common method for separating intracellular organelles. During centrifugation, organelles float or sediment until they reach their isopycnic position within the gradient. The density of an organelle depends on its content, size, shape, and the lipid:protein ratio. The degree of separation between different organelles will therefore be highly dependent on how different their isopycnic points are in a given buffer. Separation will also depend on the medium used to prepare the gradient, whether it is sucrose (the most common) or an alternative. Here we describe the use of both continuous and discontinuous (step) gradients to isolate endocytic organelles. PMID:26527762

  1. Apparatus and method for centrifugation and robotic manipulation of samples

    NASA Technical Reports Server (NTRS)

    Vellinger, John C. (Inventor); Ormsby, Rachel A. (Inventor); Kennedy, David J. (Inventor); Thomas, Nathan A. (Inventor); Shulthise, Leo A. (Inventor); Kurk, Michael A. (Inventor); Metz, George W. (Inventor)

    2007-01-01

    A device for centrifugation and robotic manipulation of specimen samples, including incubating eggs, and uses thereof are provided. The device may advantageously be used for the incubation of avian, reptilian or any type of vertebrate eggs. The apparatus comprises a mechanism for holding samples individually, rotating them individually, rotating them on a centrifuge collectively, injecting them individually with a fixative or other chemical reagent, and maintaining them at controlled temperature, relative humidity and atmospheric composition. The device is applicable to experiments involving entities other than eggs, such as invertebrate specimens, plants, microorganisms and molecular systems.

  2. High-speed centrifugation induces aggregation of extracellular vesicles

    PubMed Central

    Linares, Romain; Tan, Sisareuth; Gounou, Céline; Arraud, Nicolas; Brisson, Alain R.

    2015-01-01

    Plasma and other body fluids contain cell-derived extracellular vesicles (EVs), which participate in physiopathological processes and have potential biomedical applications. In order to isolate, concentrate and purify EVs, high-speed centrifugation is often used. We show here, using electron microscopy, receptor-specific gold labelling and flow cytometry, that high-speed centrifugation induces the formation of EV aggregates composed of a mixture of EVs of various phenotypes and morphologies. The presence of aggregates made of EVs of different phenotypes may lead to erroneous interpretation concerning the existence of EVs harbouring surface antigens from different cell origins. PMID:26700615

  3. The use of centrifugation to study early Drosophila embryogenesis

    NASA Technical Reports Server (NTRS)

    Abbott, M. K.; Spooner, B. S. (Principal Investigator)

    1993-01-01

    By the end of 10th nuclear cycle, the somatic nuclei of the Drosophila embryo have migrated to the periphery of the egg. Centrifugation of embryos did not result in the displacement of these nuclei, since cytoskeletal elements anchor them to the cortex. But, mild centrifugal forces displace the centrally located, nascent yolk nuclei. If this increased sensitivity to hypergravity occurs before the beginning of nuclear differentiation during cycle 8, when the nascent yolk and somatic nuclei physically separate, then it would mark the earliest functional difference between these two lineages.

  4. 24. RW Meyer Sugar Mill: 18761889. Centrifugal inner basket, 1879. ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    24. RW Meyer Sugar Mill: 1876-1889. Centrifugal inner basket, 1879. Manufacturer, unknown. Supplied by Honolulu Iron Works, Honolulu, Hawaii, 1879. View: After sugar was granulated and cooled it was dried and drained, completely separating the sugar crystals from the molasses, in the centrifugal. Revolving at 1200 rpm the sugar charge was forced outward with the molasses flying through the holes in the brass lining. Dried sugar was left behind in the inner basket and was dug out by hand. - R. W. Meyer Sugar Mill, State Route 47, Kualapuu, Maui County, HI

  5. Analysis of the gas-dynamic performance of a vaned diffuser with given velocity distribution along the vane's surfaces

    NASA Astrophysics Data System (ADS)

    Kalinkevych, M.; Obukhov, O.; Obukhova, O.; Miroshnychenko, A.

    2015-08-01

    Extension of the effective range of vaned diffusers is one of the promising ways to improve the centrifugal compressor's stages which are used in numerous fields of industry. The new method of profiling of the diffuser vanes has been developed using Stratford's results and boundary layer theory by Loytsanskiy. The developed method is based on the solution of the inverse task of gas-dynamic using given velocity distribution along the vane's surface. Comparison of the results of numerical simulations for different diffusers has shown that the performance of the diffuser designed with the resulting velocity distribution are better. Influence of the vane profile, number of the vanes, diffuser outlet diameter and the diffuser width on diffuser characteristics has been investigated. The results of the simulations have been used to formulate recommendations on the design of high-effectiveness vaned diffusers for centrifugal stages of different types.

  6. Reynolds and Favre-averaged rapid distortion theory for compressible, ideal-gas turbulence 

    E-print Network

    Lavin, Tucker Alan

    2007-09-17

    Compressible ideal-gas turbulence subjected to homogeneous shear is investigated at the rapid distortion limit. Specific issues addressed are (i) the interaction between kinetic and internal energies and role of pressure-dilatation; (ii...

  7. An interpretation of the phenol nitration mechanism in the gas phase using G3(MP2)//B3-CEP theory.

    PubMed

    Rocha, Carlos Murilo Romero; Rodrigues, José Augusto Rosário; Moran, Paulo José Samenho; Custodio, Rogério

    2014-12-01

    G3(MP2)//B3-CEP theory was applied to study the mechanism of phenol nitration in the gas phase, as promoted by the electrophile NO2 (+). The results of studying this mechanism at the G3(MP2)//B3-CEP level pointed to the occurrence of a single-electron transfer (SET) from the aromatic ?-system to the nitronium ion prior to ?-complex formation. The formation of an initial ?-complex between the nitronium ion and phenol was not observed. Excellent agreement between the activation barriers predicted by G3(MP2)//B3-CEP and those yielded by other, more accurate, versions of the G3 theory showed that the former is a useful tool for studying reaction mechanisms, as G3(MP2)//B3-CEP is much less computationally expensive than other high-level methods. PMID:25433598

  8. Experimental and Theoretical Study on Circular Disk Particles Suspended in Centrifugal and Non-Centrifugal Force Environments

    SciTech Connect

    Torii, Shuichi; Watanabe, Yoshimi; Tanaka, Satoyuki; Yano, Toshiaki; Iino, Naoko

    2008-02-15

    Theoretical and experimental studies are performed on suspension particle motion in Centrifugal and Non-Centrifugal Force Environment, i.e., in both an axially rotating drum and a stable liquid tank. The particle velocity of circular disks is measured by PTV (Particle Tracking Velocimetry) method and is predicted by BBO (Basset-Boussinesq-Ossen) equation. It is found that (1) as time progresses, one side of the disk in the axially rotating drum is attracted toward the drum wall and its velocity is affected by the rotating speed, (2) when the particle moves in the Stokes' regime, its velocity is linearly increased with the distance from the center of the drum, (3) in contrast, the autorotation of the disk occurs in the non-centrifugal force field, and (4) the corresponding drag coefficient in the low Reynolds number region is in good agreement with the theoretical value of the sphere.

  9. 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.

  10. Dynamic stress analysis of sewage centrifugal pump impeller based on two-way coupling method

    NASA Astrophysics Data System (ADS)

    Pei, Ji; Yuan, Shouqi; Yuan, Jianping

    2014-03-01

    Current research on the operational reliability of centrifugal pumps has mainly focused on hydrodynamic instability. However, the interaction between the fluid and structure has not been sufficiently considered; this interaction can cause vibration and dynamic stress, which can affect the reliability. In this study, the dynamic stresses in a single-blade centrifugal pump impeller are analysed under different operating conditions; the two-way coupling method is used to calculate the fluid-structure interaction. Three-dimensional unsteady Reynolds-averaged Navier-Stokes equations are solved with the SST k-? turbulence model for the fluid in the whole flow passage, while transient structure dynamic analysis is used with the finite element method for the structure side. The dynamic stresses in the rotor system are computed according to the fourth strength theory. The stress results show that the highest stress is near the loose bearing and that the equivalent stress increases with the flow rate because the dynamic stresses are closely related to the pressure load. The stress distributions on the blade pressure side, suction side, leading edge, and trailing edge are each analysed for different flow rates; the highest stress distribution is found on the pressure side. On the blade pressure side, a relatively large stress is found near the trailing edge and hub side. Based on these results, a stress distribution prediction method is proposed for centrifugal pumps, which considers the interaction between the fluid and structure. The method can be used to check the dynamic stress at different flow rates when optimising the pump design to increase the pump reliability.

  11. Cushioned centrifugation of stallion semen: factors impacting equine sperm recovery rate and quality 

    E-print Network

    Waite, Jessica Arlene

    2009-05-15

    Centrifugation of stallion semen is an integral part of the cryopreservation procedure, primarily allowing for the concentration of sperm and removal of seminal plasma. In addition, centrifugation is required for maximizing ...

  12. 21 CFR 862.2140 - Centrifugal chemistry analyzer for clinical use.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 2013-04-01 false Centrifugal chemistry analyzer for clinical use. 862.2140...CONTINUED) MEDICAL DEVICES CLINICAL CHEMISTRY AND CLINICAL TOXICOLOGY DEVICES Clinical...Instruments § 862.2140 Centrifugal chemistry analyzer for clinical use. (a)...

  13. 21 CFR 862.2140 - Centrifugal chemistry analyzer for clinical use.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 2012-04-01 false Centrifugal chemistry analyzer for clinical use. 862.2140...CONTINUED) MEDICAL DEVICES CLINICAL CHEMISTRY AND CLINICAL TOXICOLOGY DEVICES Clinical...Instruments § 862.2140 Centrifugal chemistry analyzer for clinical use. (a)...

  14. 21 CFR 862.2140 - Centrifugal chemistry analyzer for clinical use.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 2014-04-01 false Centrifugal chemistry analyzer for clinical use. 862.2140...CONTINUED) MEDICAL DEVICES CLINICAL CHEMISTRY AND CLINICAL TOXICOLOGY DEVICES Clinical...Instruments § 862.2140 Centrifugal chemistry analyzer for clinical use. (a)...

  15. 21 CFR 864.9275 - Blood bank centrifuge for in vitro diagnostic use.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ...Drugs 8 2010-04-01 2010-04-01 false Blood bank centrifuge for in vitro diagnostic use. 864...DEVICES Products Used In Establishments That Manufacture Blood and Blood Products § 864.9275 Blood bank centrifuge for...

  16. Effects of centrifugation stress on pituitary-gonadal function in male rats

    NASA Technical Reports Server (NTRS)

    Gray, G. D.; Smith, E. R.; Damassa, D. A.; Davidson, J. M.

    1980-01-01

    The effects of centrifugation for various lengths of time on circulating levels of luteinizing hormone (LH) and testosterone in male rats were investigated. In a chronic 52-day experiment, centrifugation at 4.1 G significantly reduced LH and testosterone levels for the entire period. Centrifugation at 2.3 G had less effect inasmuch as LH levels were not significantly decreased and testosterone levels were significantly reduced only during the first few days of centrifugation. In more acute experiments, centrifugation at 4.1 G for 4 h resulted in reduced testosterone levels, whereas centrifugation for 15 min did not significantly alter the hormone levels. These results indicate that centrifugation can decrease circulating LH and testosterone levels if the gravitational force is of sufficient magnitude and is maintained for a period of hours. Chronic centrifugation may also inhibit the acute excitatory response of LH to handling and ether stress.

  17. Scales modified for use on board the human centrifuge in the MIT Man Vehicle Lab

    E-print Network

    Samuelson, Heather Marie

    2006-01-01

    The MIT Man Vehicle Lab (MVL) is currently performing research on the effects of rotational artificial gravity on humans through the use of a short-radius centrifuge. The MVL centrifuge allows subjects to spin in the supine ...

  18. 21 CFR 862.2140 - Centrifugal chemistry analyzer for clinical use.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 2011-04-01 false Centrifugal chemistry analyzer for clinical use. 862.2140...CONTINUED) MEDICAL DEVICES CLINICAL CHEMISTRY AND CLINICAL TOXICOLOGY DEVICES Clinical...Instruments § 862.2140 Centrifugal chemistry analyzer for clinical use. (a)...

  19. Pasteurization of grapefruit juice using a centrifugal ultraviolet light irradiator

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The pharmaceutical industry uses UV irradiators to inactivate viruses in liquids without heat. The penetration depth of UV in some liquids, such as serum plasma, can be short. To overcome this, very thin films may be produced by centrifugal force, small diameter tubing, or other means. Many liquid f...

  20. DEMONSTRATION BULLETIN: THE PLASMA CENTRIFUGAL FURNACE RETECH, INC.

    EPA Science Inventory

    The plasma centrifugal furnace is a thermal technology which uses the heat generated from a plasma torch to decontaminate metal and organic contaminated waste. This is accomplished by melting metal-bearing solids and, in the process, thermally destroying organic contaminants. The...

  1. Regulation of the centrifugal interchange cycle in Saturn's inner magnetosphere

    E-print Network

    Winglee, Robert M.

    Regulation of the centrifugal interchange cycle in Saturn's inner magnetosphere A. Kidder,1 R. M; published 7 February 2009. [1] Multifluid modeling of Saturn's magnetosphere produces the first numerical direction, because of the fact that the magnetic field is too weak to keep the fingers solidly locked

  2. Effect of chronic centrifugation on body composition in the rat.

    NASA Technical Reports Server (NTRS)

    Pitts, G. C.; Bull, L. S.; Oyama, J.

    1972-01-01

    Two groups of adult female rats were chronically centrifuged for 60 days (2.76 G, 4.15 G, controls at 1.00 G). Live weights of centrifugal rats decreased about 20 g (6%) per Delta 1 G above control. This weight loss comprised reductions in both body fat and fat-free body weight (FFBW) as determined by body-composition studies on eight rats per group killed at the end of centrifugation. Of nine components constituting the FFBW, only skeletal muscle, liver, and heart changed significantly in weight. Chemical composition showed reductions (compared with controls) in the fat fraction of most components and increases in the water fraction of liver and gut. Identical measurements were made on the remaining eight rats per group killed 43 days after return to 1 G. Neither centrifuged group had reached the control body-weight level at this time. No statistically significant effect of previous G level was found in any of the body-composition parameters. The possible involvment of physiological regulation was considered.

  3. Prediction of performance of centrifugal pumps during starts under pressure

    NASA Technical Reports Server (NTRS)

    Rostafinski, W.

    1969-01-01

    Method which calculates start-up characteristics of centrifugal pumps reveals a capacity to predict pressure drop characteristics of pumps with vaned diffusers. Calculations are based on pump geometry, design-point flow, speed, and pressure rise, and the pump characteristic within range of approximately ten percent of the design-point flow.

  4. Latex micro-balloon pumping in centrifugal microfluidic platforms.

    PubMed

    Aeinehvand, Mohammad Mahdi; Ibrahim, Fatimah; Harun, Sulaiman Wadi; Al-Faqheri, Wisam; Thio, Tzer Hwai Gilbert; Kazemzadeh, Amin; Madou, Marc

    2014-03-01

    Centrifugal microfluidic platforms have emerged as point-of-care diagnostic tools. However, the unidirectional nature of the centrifugal force limits the available space for multi-step processes on a single microfluidic disc. To overcome this limitation, a passive pneumatic pumping method actuated at high rotational speeds has been previously proposed to pump liquid against the centrifugal force. In this paper, a novel micro-balloon pumping method that relies on elastic energy stored in a latex membrane is introduced. It operates at low rotational speeds and pumps a larger volume of liquid towards the centre of the disc. Two different micro-balloon pumping mechanisms have been designed to study the pump performance at a range of rotational frequencies from 0 to 1500 rpm. The behaviour of the micro-balloon pump on the centrifugal microfluidic platforms has been theoretically analysed and compared with the experimental data. The experimental data show that the developed pumping method dramatically decreases the required rotational speed to pump liquid compared to the previously developed pneumatic pumping methods. It also shows that within a range of rotational speed, a desirable volume of liquid can be stored and pumped by adjusting the size of the micro-balloon. PMID:24441792

  5. Measurements of the rotordynamic shroud forces for centrifugal pumps

    NASA Technical Reports Server (NTRS)

    Guinzburg, A.; Brennen, C. E.; Acosta, A. J.; Caughey, T. K.

    1990-01-01

    An experiment was designed to measure the rotordynamic shroud forces on a centrifugal pump impeller. The measurements were done for various whirl/impeller speed ratios and for different flow rates. A destabilizing tangential force was measured for small positive whirl ratios and this force decreased with increasing flow rate.

  6. Unsteady flow in a viscous oil transporting centrifugal pump

    NASA Astrophysics Data System (ADS)

    Li, Wen-Guang

    2011-12-01

    Acoustic resonances are frequently fatal problems in centrifugal pump operations. Low pressure pulsation of fluid in the blade pass frequency is helpful to prevent from such problems. In addition, for a high quality centrifugal pump, a lower broadband noise level is also on demand. The acoustic resonance and broadband noise are associated with unsteadiness of flow in the pump. Even there exist extensive analyses of unsteady flow in centrifugal pumps by means of CFD so far, the effect of high viscosity of fluid pumped on the unsteadiness of flow feature remains unclear. Thus, the unsteady flow in an experimental centrifugal pump was exploited numerically when it transported the liquids with different viscosities. The velocity profiles at the impeller discharge were validated with the results of LDV measurement for water. The viscosity effect on the fluctuation of flow in the volute was clarified quantitatively. It was shown the increasing viscosity of fluid makes the fluctuation in flow variables less substantial and results into a less noticed tendency of separation of flow from the blade pressure side.

  7. 8. TENTERING GEAR OF EAST BURR STONES; CENTRIFUGAL GOVERNOR MOUNTED ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    8. TENTERING GEAR OF EAST BURR STONES; CENTRIFUGAL GOVERNOR MOUNTED ON STONE SPINDLE; ALSO SEEN IS THE CHUTE FROM THE TUN OF THE BURR STONES; HANGING IN THE BACKGROUND ARE THE MILL SAILS. - Hayground Windmill, Windmill Lane, East Hampton, Suffolk County, NY

  8. SEPARATION OF METALS IN WASTEWATER SLUDGE BY CENTRIFUGAL CLASSIFICATION

    EPA Science Inventory

    Municipal wastewater sludges frequently contain undesirably high concentrations of heavy metals and/or organic pollutants which interfere with beneficial use of sludge on farmland and with some disposal practices such as ocean disposal. Centrifugal classification is a low-cost pr...

  9. Modeling for surge control of centrifugal compresssors: comparison with experiment

    E-print Network

    Gravdahl, Jan Tommy

    approach is used with energy based control design in mind. When e.g. using passivity as a design toolModeling for surge control of centrifugal compresssors: comparison with experiment Jan Tommy as a state in order to perform energy based active surge control. The response of the model is compared

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

    E-print Network

    Haigh, Stuart

    or satellite imaging, comparing photographs from before and after the earthquake and measuring the movementPaper No. : 0317 LATERAL SPREADING DURING CENTRIFUGE MODEL EARTHQUAKES Stuart K. Haigh1 , S of gently-sloping deposits of liquefiable sand is a cause of much damage in earthquakes, reportedly more

  11. 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.

  12. Return to Flying Duties Following Centrifuge or Vibration Exposures

    NASA Technical Reports Server (NTRS)

    Scheuring, Richard A.; Clarke, Jonathan; Jones, Jeffrey A.

    2009-01-01

    Introduction: In an effort to determine the human performance limits for vibration in spacecraft being developed by NASA, astronauts were evaluated during a simulated launch profile in a centrifuge/vibration environment and separate vibration-only simulation. Current USAF and Army standards for return to flight following centrifuge exposures require 12-24 hours to pass before a crewmember may return to flying duties. There are no standards on vibration exposures and return to flying duties. Based on direct observation and provocative neurological testing of the astronauts, a new standard for return to flying duties following centrifuge and/or vibration exposures was established. Methods: 13 astronaut participants were exposed to simulated launch profiles in a + 3.5 Gx bias centrifuge/vibration environment and separately on a vibration table at the NASA-Ames Research Center. Each subject had complete neurological evaluations pre- and post-exposure for the centrifuge/vibration runs with the NASA neurological function rating scale (NFRS). Subjects who participated in the vibration-only exposures had video oculography performed with provocative maneuvers in addition to the NFRS. NFRS evaluations occurred immediately following each exposure and at 1 hour post-run. Astronauts who remained symptomatic at 1 hour had repeat NFRS performed at 1 hour intervals until the crewmember was asymptomatic. Results: Astronauts in the centrifuge/vibration study averaged a 3-5 point increase in NFRS scores immediately following exposure but returned to baseline 3 hours post-run. Subjects exposed to the vibration-only simulation had a 1-3 point increase following exposure and returned to baseline within 1-2 hours. Pre- and post- vibration exposure video oculography did not reveal any persistent ocular findings with provocative testing 1 hour post-exposure. Discussion: Based on direct observations and objective measurement of neurological function in astronauts following simulated launch profiles, asymptomatic individuals are allowed to return to flying duties within 3 hours following centrifuge/vibration and 2 hours after vibration-only exposures.

  13. 40 CFR Appendix - Alternative Organic HAP Emissions Limits for Open Molding, Centrifugal Casting, and SMC...

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ...system that moves heated air through the mold 27 lb/ton. 8. Centrifugal casting...system that moves heated air through the mold 21 lb/ton. 7. Centrifugal casting...system that moves ambient air through the mold 2 lb/ton. 8. Centrifugal...

  14. 40 CFR Appendix - Alternative Organic HAP Emissions Limits for Open Molding, Centrifugal Casting, and SMC...

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ...system that moves heated air through the mold 27 lb/ton. 8. Centrifugal casting...system that moves heated air through the mold 21 lb/ton. 7. Centrifugal casting...system that moves ambient air through the mold 2 lb/ton. 8. Centrifugal...

  15. 40 CFR Appendix - Alternative Organic HAP Emissions Limits for Open Molding, Centrifugal Casting, and SMC...

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ...system that moves heated air through the mold 27 lb/ton. 8. Centrifugal casting...system that moves heated air through the mold 21 lb/ton. 7. Centrifugal casting...system that moves ambient air through the mold 2 lb/ton. 8. Centrifugal...

  16. 21 CFR 864.9285 - Automated cell-washing centrifuge for immuno-hematology.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Automated cell-washing centrifuge for immuno... Establishments That Manufacture Blood and Blood Products § 864.9285 Automated cell-washing centrifuge for immuno-hematology. (a) Identification. An automated cell-washing centrifuge for immuno-hematology is a device...

  17. 21 CFR 864.9285 - Automated cell-washing centrifuge for immuno-hematology.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Automated cell-washing centrifuge for immuno... Establishments That Manufacture Blood and Blood Products § 864.9285 Automated cell-washing centrifuge for immuno-hematology. (a) Identification. An automated cell-washing centrifuge for immuno-hematology is a device...

  18. 21 CFR 864.9285 - Automated cell-washing centrifuge for immuno-hematology.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Automated cell-washing centrifuge for immuno... Establishments That Manufacture Blood and Blood Products § 864.9285 Automated cell-washing centrifuge for immuno-hematology. (a) Identification. An automated cell-washing centrifuge for immuno-hematology is a device...

  19. 21 CFR 864.9285 - Automated cell-washing centrifuge for immuno-hematology.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Automated cell-washing centrifuge for immuno... Establishments That Manufacture Blood and Blood Products § 864.9285 Automated cell-washing centrifuge for immuno-hematology. (a) Identification. An automated cell-washing centrifuge for immuno-hematology is a device...

  20. 21 CFR 864.9285 - Automated cell-washing centrifuge for immuno-hematology.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Automated cell-washing centrifuge for immuno... Establishments That Manufacture Blood and Blood Products § 864.9285 Automated cell-washing centrifuge for immuno-hematology. (a) Identification. An automated cell-washing centrifuge for immuno-hematology is a device...

  1. Numerical modeling and experimental validation of uniform microchamber filling in centrifugal microfluidics

    E-print Network

    Banerjee, Debjyoti

    )-like centrifugal microfluidic platform holds many advantages due to its unique pumping and valving mechanisms.15­17 Centrifugal pumping is dependent in part on rotation frequency and radial distance from the CD centerNumerical modeling and experimental validation of uniform microchamber filling in centrifugal

  2. IEEE Visualization Contest 2011 Visualizing Unsteady Vortical Behavior of a Centrifugal Pump

    E-print Network

    IEEE Visualization Contest 2011 Visualizing Unsteady Vortical Behavior of a Centrifugal Pump number 226042. em eg We present our results analyzing a centrifugal pump as a part of the IEEE Visualization Contest 2011. The given data set represents a high resolution simulation of a centrifugal pump

  3. 21 CFR 864.9275 - Blood bank centrifuge for in vitro diagnostic use.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Blood bank centrifuge for in vitro diagnostic use... Manufacture Blood and Blood Products § 864.9275 Blood bank centrifuge for in vitro diagnostic use. (a) Identification. A blood bank centrifuge for in vitro diagnostic use is a device used only to separate blood...

  4. 21 CFR 864.9275 - Blood bank centrifuge for in vitro diagnostic use.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Blood bank centrifuge for in vitro diagnostic use... Manufacture Blood and Blood Products § 864.9275 Blood bank centrifuge for in vitro diagnostic use. (a) Identification. A blood bank centrifuge for in vitro diagnostic use is a device used only to separate blood...

  5. 21 CFR 864.9275 - Blood bank centrifuge for in vitro diagnostic use.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Blood bank centrifuge for in vitro diagnostic use... Manufacture Blood and Blood Products § 864.9275 Blood bank centrifuge for in vitro diagnostic use. (a) Identification. A blood bank centrifuge for in vitro diagnostic use is a device used only to separate blood...

  6. 21 CFR 864.9275 - Blood bank centrifuge for in vitro diagnostic use.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Blood bank centrifuge for in vitro diagnostic use... Manufacture Blood and Blood Products § 864.9275 Blood bank centrifuge for in vitro diagnostic use. (a) Identification. A blood bank centrifuge for in vitro diagnostic use is a device used only to separate blood...

  7. 21 CFR 864.9275 - Blood bank centrifuge for in vitro diagnostic use.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Blood bank centrifuge for in vitro diagnostic use... Manufacture Blood and Blood Products § 864.9275 Blood bank centrifuge for in vitro diagnostic use. (a) Identification. A blood bank centrifuge for in vitro diagnostic use is a device used only to separate blood...

  8. Performance and Dynamic Stability of General-Path Centrifugal Pendulum Vibration

    E-print Network

    Shaw, Steven W.

    Performance and Dynamic Stability of General-Path Centrifugal Pendulum Vibration Absorbers A. S 48824, USA RUNNING HEADLINE: GENERAL PATH CPVAS. #12;Abstract Centrifugal pendulum vibration absorbers of multiple, identical centrifugal pendulum vibration absorbers that have general paths. The study is carried

  9. 21 CFR 864.9285 - Automated cell-washing centrifuge for immuno-hematology.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ...2013-04-01 2013-04-01 false Automated cell-washing centrifuge for immuno-hematology...Blood Products § 864.9285 Automated cell-washing centrifuge for immuno-hematology. (a) Identification. An automated cell-washing centrifuge for...

  10. 21 CFR 864.9285 - Automated cell-washing centrifuge for immuno-hematology.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ...2012-04-01 2012-04-01 false Automated cell-washing centrifuge for immuno-hematology...Blood Products § 864.9285 Automated cell-washing centrifuge for immuno-hematology. (a) Identification. An automated cell-washing centrifuge for...

  11. 21 CFR 864.9285 - Automated cell-washing centrifuge for immuno-hematology.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ...2010-04-01 2010-04-01 false Automated cell-washing centrifuge for immuno-hematology...Blood Products § 864.9285 Automated cell-washing centrifuge for immuno-hematology. (a) Identification. An automated cell-washing centrifuge for...

  12. 21 CFR 864.9285 - Automated cell-washing centrifuge for immuno-hematology.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ...2014-04-01 2014-04-01 false Automated cell-washing centrifuge for immuno-hematology...Blood Products § 864.9285 Automated cell-washing centrifuge for immuno-hematology. (a) Identification. An automated cell-washing centrifuge for...

  13. 21 CFR 864.9285 - Automated cell-washing centrifuge for immuno-hematology.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ...2011-04-01 2011-04-01 false Automated cell-washing centrifuge for immuno-hematology...Blood Products § 864.9285 Automated cell-washing centrifuge for immuno-hematology. (a) Identification. An automated cell-washing centrifuge for...

  14. Using game theory approach to interpret stable policies for Iran's oil and gas common resources conflicts with Iraq and Qatar

    NASA Astrophysics Data System (ADS)

    Esmaeili, Maryam; Bahrini, Aram; Shayanrad, Sepideh

    2015-08-01

    Oil and gas as the non-renewable resources are considered very valuable for the countries with petroleum economics. These resources are not only diffused equally around the world, but also they are common in some places which their neighbors often come into conflicts. Consequently, it is vital for those countries to manage their resource utilization. Lately, game theory was applied in conflict resolution of common resources, such as water, which is a proof of its efficacy and capability. This paper models the conflicts between Iran and its neighbors namely Qatar and Iraq between their oil and gas common resources using game theory approach. In other words, the future of these countries will be introduced and analyzed by some well-known 2 × 2 games to achieve a better perspective of their conflicts. Because of information inadequacy of the players, in addition to Nash Stability, various solution concepts are used based on the foresight, disimprovements, and knowledge of preferences. The results of mathematical models show how the countries could take a reasonable strategy to exploit their common resources.

  15. Centrifuge impact cratering experiments: Scaling laws for non-porous targets

    NASA Technical Reports Server (NTRS)

    Schmidt, Robert M.

    1987-01-01

    A geotechnical centrifuge was used to investigate large body impacts onto planetary surfaces. At elevated gravity, it is possible to match various dimensionless similarity parameters which were shown to govern large scale impacts. Observations of crater growth and target flow fields have provided detailed and critical tests of a complete and unified scaling theory for impact cratering. Scaling estimates were determined for nonporous targets. Scaling estimates for large scale cratering in rock proposed previously by others have assumed that the crater radius is proportional to powers of the impactor energy and gravity, with no additional dependence on impact velocity. The size scaling laws determined from ongoing centrifuge experiments differ from earlier ones in three respects. First, a distinct dependence of impact velocity is recognized, even for constant impactor energy. Second, the present energy exponent for low porosity targets, like competent rock, is lower than earlier estimates. Third, the gravity exponent is recognized here as being related to both the energy and the velocity exponents.

  16. Centrifugal compressor surge detecting method based on wavelet analysis of unsteady pressure fluctuations in typical stages

    NASA Astrophysics Data System (ADS)

    Izmaylov, R.; Lebedev, A.

    2015-08-01

    Centrifugal compressors are complex energy equipment. Automotive control and protection system should meet the requirements: of operation reliability and durability. In turbocompressors there are at least two dangerous areas: surge and rotating stall. Antisurge protecting systems usually use parametric or feature methods. As a rule industrial system are parametric. The main disadvantages of anti-surge parametric systems are difficulties in mass flow measurements in natural gas pipeline compressor. The principal idea of feature method is based on the experimental fact: as a rule just before the onset of surge rotating or precursor stall established in compressor. In this case the problem consists in detecting of unsteady pressure or velocity fluctuations characteristic signals. Wavelet analysis is the best method for detecting onset of rotating stall in spite of high level of spurious signals (rotating wakes, turbulence, etc.). This method is compatible with state of the art DSP systems of industrial control. Examples of wavelet analysis application for detecting onset of rotating stall in typical stages centrifugal compressor are presented. Experimental investigations include unsteady pressure measurement and sophisticated data acquisition system. Wavelet transforms used biorthogonal wavelets in Mathlab systems.

  17. Screen bowl centrifuge: a high-efficiency particle size separator

    SciTech Connect

    Mohanty, M.K.; Zhang, B.; Khanna, N.; Palit, A.; Dube, B.

    2008-05-15

    Over the years, screen bowl centrifuges have been widely used for dewatering fine coal in coal preparation plants in the United States and elsewhere. It is generally recognized in the engineering and scientific communities that screen bowl centrifuges provide some degree of particle size separation while dewatering fine coal in a common application. However, the extent of differential partitioning of coarse and fine particles achievable by a screen bowl centrifuge has not been systematically studied in the past. The present investigation was aimed at conducting a parametric study using a statistically designed experimental program to better understand and optimize the size classification performance of a screen bowl centrifuge. A continuously operating screen bowl centrifuge having a bowl diameter of 0.5 m was used for this study at the Illinois Coal Development Park. Three key operating parameters, i.e., feed flow rate, feed solid content and pool depth, were varied to conduct a total of 17 experiments using a three-level factorial test matrix. Some of the best size separation performances achieved in this study may be described as having an imperfection value of 0.13 at an effective separation size (d(50c)) of 38 mu m and an imperfection value of 0.27 at an effective separation size (d(50c)) of 2.8 mu m. Due to an effective separation of ultrafine high ash materials, the ash content of the screen bowl feed was reduced from 22.3% to a minimum of 8.84% with a combustible recovery of 84.1% and an ash rejection of 71.6%. A higher combustible recovery of 92.1% was achieved at a product ash content of 12.5% with a d(50c) of 2.8 mu m and imperfection of 0.27.

  18. Thermal Creep of a Rarefied Gas on the Basis of Non-linear Korteweg-Theory

    NASA Astrophysics Data System (ADS)

    Kim, Yong-Jung; Lee, Min-Gi; Slemrod, Marshall

    2015-02-01

    The study of thermal transpiration, more commonly called thermal creep, is accomplished by use of Korteweg's theory of capillarity. Incorporation of this theory into the balance laws of continuum mechanics allows resolution of boundary value problems via solutions to systems of ordinary differential equations. The problem was originally considered by Maxwell in his classic 1879 paper M axwell (Phil Trans Roy Soc (London) 170:231-256, 1879). In that paper Maxwell derived what is now called the Burnett higher order contribution to the Cauchy stress, but was not able to solve his newly derived system of partial differential equations. In this paper the authors note that a more appropriate higher order contribution to the Cauchy stress follows from Korteweg's 1901 theory K orteweg (Arch Neerl Sci Exactes Nat Ser II 6:1-24, 1901). The appropriateness of Korteweg's theory is based on the exact summation of the Chapman-Enskog expansion given by Gorban and Karlin. The resulting balance laws are solved exactly, qualitatively, and numerically and the results are qualitatively similar to the numerical and exact results given by Aoki et al., Loyalka et al., and Struchtrup et al.

  19. THEORY OF THREE-PHASE FLOW APPLIED TO WATER-ALTERNATING-GAS ENHANCED OIL RECOVERY

    E-print Network

    the geometry of rarefaction curves and Hugoniot curves as well as the classi#12;cation of shock waves according on alternate injection of water and gas (WAG). The nonclassical \\transitional" shock wave generated in the ow in a rock core sample. We show that, in addition to classical shock and rarefaction waves, there occur two

  20. 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...

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

    E-print Network

    Mireles, Thomas Joseph

    1995-01-01

    results in a non-linear partial differential equation (i.e., pressuredependent coefficients in the differential equation). Our objective is to develop a se@-analytical solution specific to the case of compressible gas flow that will eliminate the use...

  2. 76 FR 41235 - Tres Palacios Gas Storage LLC; Notice of Application

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-07-13

    ...pursuant to section 7 of the Natural Gas Act (NGA) and part 157 the Commission's...single electric- driven centrifugal compressor for five not-yet-installed certificated 4,800hp gas-fired compressors and to construct associated...

  3. Dynamic density functional theory with hydrodynamic interactions: Theoretical development and application in the study of phase separation in gas-liquid systems

    SciTech Connect

    Kikkinides, E. S.; Monson, P. A.

    2015-03-07

    Building on recent developments in dynamic density functional theory, we have developed a version of the theory that includes hydrodynamic interactions. This is achieved by combining the continuity and momentum equations eliminating velocity fields, so the resulting model equation contains only terms related to the fluid density and its time and spatial derivatives. The new model satisfies simultaneously continuity and momentum equations under the assumptions of constant dynamic or kinematic viscosity and small velocities and/or density gradients. We present applications of the theory to spinodal decomposition of subcritical temperatures for one-dimensional and three-dimensional density perturbations for both a van der Waals fluid and for a lattice gas model in mean field theory. In the latter case, the theory provides a hydrodynamic extension to the recently studied dynamic mean field theory. We find that the theory correctly describes the transition from diffusive phase separation at short times to hydrodynamic behaviour at long times.

  4. Modeling panel detection frequencies by queuing system theory: an application in gas chromatography olfactometry.

    PubMed

    Bult, Johannes H F; van Putten, Bram; Schifferstein, Hendrik N J; Roozen, Jacques P; Voragen, Alphons G J; Kroeze, Jan H A

    2004-10-01

    In continuous vigilance tasks, the number of coincident panel responses to stimuli provides an index of stimulus detectability. To determine whether this number is due to chance, panel noise levels have been approximated by the maximum coincidence level obtained in stimulus-free conditions. This study proposes an alternative method by which to assess noise levels, derived from queuing system theory (QST). Instead of critical coincidence levels, QST modeling estimates the duration of coinciding responses in the absence of stimuli. The proposed method has the advantage over previous approaches that it yields more reliable noise estimates and allows for statistical testing. The method was applied in an olfactory detection experiment using 16 panelists in stimulus-present and stimulus-free conditions. We propose that QST may be used as an alternative to signal detection theory for analyzing data from continuous vigilance tasks. PMID:15751471

  5. Rayleigh-Taylor Instability within Sediment Layers Due to Gas Retention: Preliminary Theory and Experiments

    SciTech Connect

    Gauglitz, Phillip A.; Wells, Beric E.; Buchmiller, William C.; Rassat, Scot D.

    2013-03-21

    In Hanford underground waste storage tanks, a typical waste configuration is settled beds of waste particles beneath liquid layers. The settled beds are typically composed of layers, and these layers can have different physical and chemical properties. One postulated configuration within the settled bed is a less-dense layer beneath a more-dense layer. The different densities can be a result of different gas retention in the layers or different degrees of settling and compaction in the layers. This configuration can experience a Rayleigh-Taylor (RT) instability where the less dense lower layer rises into the upper layer. Previous studies of gas retention and release have not considered potential buoyant motion within a settle bed of solids. The purpose of this report is to provide a review of RT instabilities, discuss predictions of RT behavior for sediment layers, and summarize preliminary experimental observations of RT instabilities in simulant experiments.

  6. Lyapunov Exponents from Kinetic Theory for a Dilute, Field-driven Lorentz Gas

    E-print Network

    H. van Beijeren; J. R. Dorfman; E. G. D. Cohen; H. A. Posch; Ch. Dellago

    1996-06-14

    Positive and negative Lyapunov exponents for a dilute, random, two-dimensional Lorentz gas in an applied field, $\\vec{E}$, in a steady state at constant energy are computed to order $E^{2}$. The results are: $\\lambda_{\\pm}=\\lambda_{\\pm}^{0}-a_{\\pm}(qE/mv)^{2}t_{0}$ where $\\lambda_{\\pm}^{0}$ are the exponents for the field-free Lorentz gas, $a_{+}=11/48, a_{-}=7/48$, $t_{0}$ is the mean free time between collisions, $q$ is the charge, $m$ the mass and $v$ is the speed of the particle. The calculation is based on an extended Boltzmann equation in which a radius of curvature, characterizing the separation of two nearby trajectories, is one of the variables in the distribution function. The analytical results are in excellent agreement with computer simulations. These simulations provide additional evidence for logarithmic terms in the density expansion of the diffusion coefficient.

  7. Ocular Counter-Rolling During Centrifugation and Static Tilt

    NASA Technical Reports Server (NTRS)

    Cohen, Bernard; Clement, Gilles; Moore, Steven; Curthoys, Ian; Dai, Mingjia; Koizuka, Izumi; Kubo, Takeshi; Raphan, Theodore

    2003-01-01

    Activation of the gravity sensors in the inner ear-the otoliths-generates reflexes that act to maintain posture and gaze. Ocular counter-rolling (OCR) is an example of such a reflex. When the head is tilted to the side, the eyes rotate around the line of sight in the opposite direction (i.e., counter-rolling). While turning comers, undergoing centrifugation, or making side-to-side tilting head movements, the OCR reflex orients the eyes towards the sum of the accelerations from body movements and gravity. Deconditioning of otolith-mediated reflexes following adaptation to microgravity has been proposed as the basis of many of the postural, locomotor, and gaze control problems experienced by returning astronauts. Evidence suggests that OCR is reduced postflight in about 75% of astronauts tested; but the data are sparse, primarily due to difficulties in recording rotational eye movements. During the Neurolab mission, a short-arm human centrifuge was flown that generated sustained sideways accelerations of 0.5-G and one-G to the head and upper body. This produces OCR; and so for the first time, the responses to sustained centrifugation could be studied without the influence of Earth's gravity on the results. This allowed us to determine the relative importance of sideways and vertical acceleration in the generation of OCR. This also provided the first test of the effects of exposure to artificial gravity in space on postflight otolith-ocular reflexes. There was little difference between the responses to centrifugation in microgravity and on Earth. In both conditions, the induced OCR was roughly proportional to the applied acceleration, with the OCR magnitude during 0.5-G centrifugation approximately 60% of that generated during one-G centrifugation. The overall mean OCR from the four payload crewmembers in response to one-G of sideways acceleration was 5.7 plus or minus 1.1 degree (mean and SD) on Earth. Inflight one-G centrifugation generated 5.7 plus or minus 1.1 degree of OCR, which was a small but significant decrease in OCR magnitude. The postflight OCR was 5.9 plus or minus 1.4 degree, which was not significantly different from preflight values. During both 0.5-G and one-G centrifugation in microgravity, where the head vertical gravitational component was absent, the OCR magnitude was not significantly different from that produced by an equivalent acceleration during static tilt on Earth. This suggests that the larger OCR magnitude observed during centrifugation on Earth was due to the larger body vertical linear acceleration component, which may have activated either the otoliths or the body tilt receptors. In contrast to previous studies, there was no decrease in OCR gain postflight. Our findings raise the possibility that inflight exposure to artificial gravity, in the form of intermittent one-G and 0.5-G centripetal acceleration, may have been a countermeasure to deconditioning of otolith-based orientation reflexes.

  8. A covariant Fokker-Planck equation for a simple gas from relativistic kinetic theory

    SciTech Connect

    Chacon-Acosta, Guillermo; Dagdug, Leonardo; Morales-Tecotl, Hugo A.

    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.

  9. 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.

  10. NASA low-speed centrifugal compressor for 3-D viscous code assessment and fundamental flow physics research

    NASA Technical Reports Server (NTRS)

    Hathaway, M. D.; Wood, J. R.; Wasserbauer, C. A.

    1991-01-01

    A low speed centrifugal compressor facility recently built by the NASA Lewis Research Center is described. The purpose of this facility is to obtain detailed flow field measurements for computational fluid dynamic code assessment and flow physics modeling in support of Army and NASA efforts to advance small gas turbine engine technology. The facility is heavily instrumented with pressure and temperature probes, both in the stationary and rotating frames of reference, and has provisions for flow visualization and laser velocimetry. The facility will accommodate rotational speeds to 2400 rpm and is rated at pressures to 1.25 atm. The initial compressor stage being tested is geometrically and dynamically representative of modern high-performance centrifugal compressor stages with the exception of Mach number levels. Preliminary experimental investigations of inlet and exit flow uniformly and measurement repeatability are presented. These results demonstrate the high quality of the data which may be expected from this facility. The significance of synergism between computational fluid dynamic analysis and experimentation throughout the development of the low speed centrifugal compressor facility is demonstrated.

  11. Theory of electrocaloric effect in a shape-changing container: gas in a nanotube.

    PubMed

    Shklyaev, Oleg E; Mockensturm, Eric; Cole, Milton W; Crespi, Vincent H

    2014-12-31

    Driven by applied voltage or Ohmic heating, bistable nanotubes filled with gas can transform between expanded and collapsed configurations and by doing so convert energy between mechanical, electrical, and thermal forms. The electrocaloric response, a reversible change of temperature in response to applied voltage, combines the advantages of a working fluid with the lack of internal interfaces characteristic of robust solid-state thermoelectric devices. Such devices could be constructed from any conductive two-dimensional atomically thin material wrapped into an appropriate geometry. PMID:25615351

  12. A complete theory for the magnetism of an ideal gas of electrons

    SciTech Connect

    Biswas, Shyamal; Jana, Debnarayan; Sen, Swati

    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.

  13. Kinetic theory analysis of rarefied gas flow through finite length slots

    NASA Technical Reports Server (NTRS)

    Raghuraman, P.

    1972-01-01

    An analytic study is made of the flow a rarefied monatomic gas through a two dimensional slot. The parameters of the problem are the ratios of downstream to upstream pressures, the Knudsen number at the high pressure end (based on slot half width) and the length to slot half width ratio. A moment method of solution is used by assuming a discontinuous distribution function consisting of four Maxwellians split equally in angular space. Numerical solutions are obtained for the resulting equations. The characteristics of the transition regime are portrayed. The solutions in the free molecule limit are systematically lower than the results obtained in that limit by more accurate numerical methods.

  14. Field Theory of Anisotropic Quantum Hall Gas: Metrology and a Novel Quantum Hall Regime

    E-print Network

    K. Ishikawa; T. Aoyama; Y. Ishizuka; N. Maeda

    2003-09-06

    The von Neumann lattice representation is a convenient representation for studying several intriguing physics of quantum Hall systems. In this formalism, electrons are mapped to lattice fermions. A topological invariant expression of the Hall conductance is derived and is used for the proof of the integer quantum Hall effect in the realistic situation. Anisotropic quantum Hall gas is investigated based on the Hartree-Fock approximation in the same formalism. Thermodynamic properties, transport properties, and unusual response under external modulations are found. Implications for the integer quantum Hall effect in the finite systems are also studied and a new quantum Hall regime with non-zero longitudinal resistance is shown to exist.

  15. Kinetic theory model for the flow of a simple gas from a two-dimensional nozzle

    NASA Technical Reports Server (NTRS)

    Riley, B. R.; Scheller, K. W.

    1989-01-01

    A system of nonlinear integral equations equivalent to the Krook kinetic equation for the steady state is the mathematical basis used to develop a computer code to model the flowfields for low-thrust two-dimensional nozzles. The method of characteristics was used to solve numerically by an iteration process the approximated Boltzmann equation for the number density, temperature, and velocity profiles of a simple gas as it exhausts into a vacuum. Results predict backscatter and show the effect of the inside wall boundary layer on the flowfields external to the nozzle.

  16. 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.

  17. [Magnetic field numerical calculation and analysis for magnetic coupling of centrifugal blood pump for extracorporeal circulation].

    PubMed

    Hu, Zhaoyan; Lu, Lijun; Zhang, Tianyi; Chen, Zhenglong; Zhang, Tao

    2013-12-01

    This paper mainly studies the driving system of centrifugal blood pump for extracorporeal circulation, with the core being disc magnetic coupling. Structure parameters of disc magnetic coupling are related to the ability of transferring magnetic torque. Therefore, it is necessary to carry out disc magnetic coupling permanent magnet pole number (n), air gap length (L(g)), permanent magnet thickness (L(m)), permanent magnet body inside diameter (R(i)) and outside diameter (R(o)), etc. thoroughly. This paper adopts the three-dimensional static magnetic field edge element method of Ansys for numerical calculation, and analyses the relations of magnetic coupling each parameter to transmission magnetic torque. It provides a good theory basis and calculation method for further optimization of the disc magnetic coupling. PMID:24645605

  18. Numerical simulation and uncertainty estimation in a deep-well centrifugal pump

    NASA Astrophysics Data System (ADS)

    Bai, L.; Shi, W. D.; Zhou, L.; Lu, W. G.

    2013-12-01

    One stage deep-well centrifugal pump section is investigated numerically in this study. Three-dimensional steady Reynolds-Averaged Navier-Stokes (RANS) equations are solved on high-quality fine structured grids in conjunction with the shear stress transport (SST) k-? turbulence model by employing the CFD (computational fluid dynamics) software ANSYS-Fluent 13.0. A detailed grid sensitivity analysis was carried out to analyse the influence of grid elements number. The discretization errors were calculated specifically through the Richardson extrapolation theory. The uncertainty of fine gird for the simulation in this paper was estimated as 1.23%. The prototype experimental test results were acquired and compared with the data predicted from the numerical simulation, which showed that there is a good agreement between two methods.

  19. Annular Seals of High Energy Centrifugal Pumps: Presentation of Full Scale Measurement

    NASA Technical Reports Server (NTRS)

    Florjancic, S.; Stuerchler, R.; Mccloskey, T.

    1991-01-01

    Prediction of rotordynamic behavior for high energy concentration centrifugal pumps is a challenging task which still imposes considerable difficulties. While the mechanical modeling of the rotor is solved most satisfactorily by finite element techniques, accurate boundary conditions for arbitrary operating conditions are known for journal bearings only. Little information is available on the reactive forces of annular seals, such as neck ring and interstage seals and balance pistons, and on the impeller interaction forces. The present focus is to establish reliable boundary conditions at annular seals. For this purpose, a full scale test machine was set up and smooth and serrated seal configurations measured. Dimensionless coefficients are presented and compared with a state of the art theory.

  20. Design optimization of a centrifugal pump impeller and volute using computational fluid dynamics

    NASA Astrophysics Data System (ADS)

    Kim, J. H.; Oh, K. T.; Pyun, K. B.; Kim, C. K.; Choi, Y. S.; Yoon, J. Y.

    2012-11-01

    In this study, optimization of the impeller and design of volute were carried out in order to improve the performance of a centrifugal pump. Design parameters from vane plane development for impeller design were selected and effect of the design parameters on the performance of the pump was analyzed using CFD and Response Surface Method to optimized impeller. This study also proposed the optimization geometry of pump impeller for performance improvement through the results from numerical analysis that was obtained optimum design pump; efficiency 98.2% and head 64.5m. In addition, the pump design method was suggested by designing volute which was suitable for the optimized impeller through volute design where Stepanoff theory was applied and numerical analysis.

  1. The optimization of low specific speed centrifugal pump based on incomplete sensitivities

    NASA Astrophysics Data System (ADS)

    Zhang, R. H.; Zheng, K.; Yao, L. H.; Shi, F. X.

    2012-11-01

    In this research, the optimization method for low specific speed centrifugal pump impeller based on incomplete sensitivities was proposed. The main feature of the algorithm is that it avoids solving the flow field repeatedly in one optimization cycle in finite difference method and it avoids solving the adjoint equation in adjoint method. The blade meridional plan is considered as constant, and the blade camber line was parameterize by Taylor function. The coefficients in the Taylor function were taken as the control variable. The moment acting on the blade was considered as the objective function. With the incomplete sensitivities we can get the gradient of the objective function with respect to the control variable easily, and the blade shape can be renewed according to the inverse direction of the gradient. We will find the optimum design when the objective function is minimized. The computational cost is greatly reduced. The calculation cases show that the proposed theory and method is rotational.

  2. 'Coriolis resonance' within a rotating duct. [flow induced vibrations in centrifugal compressors

    NASA Technical Reports Server (NTRS)

    Kurosaka, M.; Caruthers, J. E.

    1982-01-01

    An investigation of the unsteady disturbances of a fixed frequency within a radial duct rotating at a set speed is presented. The flow is assumed to be compressible, inviscid, and of a fluid which is a perfect gas. Equations are developed for the steady and the unsteady parts of the flow in cylindrical coordinates. The unsteady disturbances are expressed by Fourier decomposition in angular position, distance into the duct, and in time. It is found that a resonance is possible when the frequency of flow disturbances is twice the shaft-rotation frequency, considering only the radial and tangential disturbances and not the radial and circumferential disturbances. The particular point at which the resonance occurs indicates the occurrence is due to the Coriolis force, which is only present in the radial and tangential directions. It is noted that the Coriolis force can only be present in open-ended ducts, such as those found in centrifugal compressors.

  3. Centrifugally driven winds from protostellar disks. I - Wind model and thermal structure

    NASA Technical Reports Server (NTRS)

    Safier, Pedro N.

    1993-01-01

    The thermal structure of a wind that is centrifugally driven from the surface of a protostellar disk is studied. A generalized version of the Blandford and Payne self-similar wind model is introduced, and the temperature and ionization distributions in the outflow are investigated. For the evolution of atomic winds, the heat equation and the rate equations that describe the ionization and excitation state of hydrogen are solved self-consistently. Ambipolar diffusion is found to be a robust mechanism for heating the gas. In the more powerful outflows, molecular hydrogen is collisionally dissociated close to the disk surface, and hydrogen is mainly atomic within a few astronomical units from the central source. It is also demonstrated that these outflows have enough momentum to lift dust grains from the disk surface.

  4. Production of Biodiesel at Kinetic Limit Achieved in a Centrifugal Reactor/Separator

    SciTech Connect

    McFarlane, Joanna; Tsouris, Costas; Birdwell Jr, Joseph F; Lee, Denise L; Jennings, Hal L; Pahmer Boitrago, Amy M; Terpstra, Sarah M

    2010-01-01

    The kinetics of the transesterification of soybean oil has been investigated in a centrifugal reactor at temperatures from 45 to 80 C and pressures up to 2.6 bar using gas chromatography flame ionization detection (GC-FID) and infrared (IR) spectroscopy. The yields of product methyl esters were quantified using IR, proton Nuclear Magnetic Resonance (H1NMR), and viscosity measurements and were found to achieve 90% of the yield in 2 min; however, to meet ASTM specifications with one pass through the reactor, a 15 min residence time was needed. Performance was improved by sequential reactions, allowing separation of by-product glycerine and injection of additional small aliquots of methanol. The kinetics was modeled using a three-step mechanism of reversible reactions, which was used to predict performance at commercial scale. The mechanism correctly predicted the exponential decline in reaction rate as the concentration of the products allowed significant reverse reactions to occur.

  5. Improved Monodispersity of Plasmonic Nanoantennas via Centrifugal Processing

    SciTech Connect

    Tyler, Timothy P.; Henry, A.I.; Van Duyne, Richard P.; Hersam, Mark C.

    2011-02-03

    Noble metal nanoparticle clusters underlie a variety of plasmonic devices and measurements including surface-enhanced Raman spectroscopy (SERS). Because of the strong dependence of plasmonic properties on nanoparticle cluster aggregation state, the elimination of non-SERS-active structures and the refinement of the nanoparticle cluster population are critical to realizing uniform and reproducible structures for plasmonic nanoantenna applications such as SERS-based sensors. In this Letter, we report a centrifugal sorting technique for gold core/silica shell nanoparticles that host SERS reporter molecules at the gold/silica interface. The relatively massive nanoparticle clusters are sorted by sedimentation coefficient via centrifugation in a high-viscosity density gradient medium, iodixanol, which yields solutions that contain a preponderance of one aggregation state and a diminished monomer population, as determined by transmission electron microscopy, extinction spectroscopy, and SERS. A quantitative analysis of the nanoparticle sedimentation coefficients is presented, thus allowing this approach to be predictably generalized to other nanoparticle systems.

  6. Centrifuge modeling and analysis of concrete gravity dams. Final report

    SciTech Connect

    1995-11-01

    This report contains general background information on centrifuge experimentation and linear elastic fracture mechanics pertaining to concrete gravity dam models, and explains in detail the experimental methodology and procedures developed for testing concrete gravity dam models in centrifuges. An important detail in the experimental procedure is that the models are loaded upstream with water and, at fracture, have water uplift pressure within any cracks. Finally, test results and comparisons to analytical/numerical models on two types of dam specimens, that is monolithic concrete dam models and rock foundation/concrete dam models, are reported. The experimental results show good agreement with the numerical finite element analysis predictions, in terms of strains and crest displacements versus upstream water levels. Also, the monolithic concrete specimen`s crack trajectories illustrate curvilinear orientation, qualitatively verifying theoretical predictions.

  7. Pressure, centrifugal, and electrically assisted dewatering of coal

    SciTech Connect

    Bainbridge, N.W.; Johnston, B.K.; Lockhart, N.C.

    1995-10-01

    CSIRO and its collaborators have developed a major R and D project on dewatering of coal. This involves sub-projects on (1) the fundamentals of coal-water associations; (2) reducing the variability of product moisture levels from small coal centrifuges; (3) process mechanisms and optimization for fine coal dewatering; (4) pilot scale testing, engineering development and innovation. Results from each of these sub-projects are presented, and the pilot facility incorporating a vacuum filter, belt press, membrane press, hyperbaric filters and centrifuges, is discussed. The vacuum filter and membrane press can be configured for electric-field assisted dewatering, which provides substantial enhancements in the rate and degree of dewatering for fine coal, coal tailings, and other suspensions.

  8. Centrifugal Field-Induced Colloidal Assembly: From Chaos to Order.

    PubMed

    Chen, Mengdi; Cölfen, Helmut; Polarz, Sebastian

    2015-07-28

    Given a certain binary phase, its crystal structure can usually be rationalized by thermodynamics and packing rules. However, there is still no fundamental understanding of how metastable solids form and how this is influenced by kinetic factors. Furthermore, the very early stages of crystallization remain vague. We present an experimental study using a binary mixture of colloidal particles as a model. Particle assembly is provoked by centrifugation, and the degree of separation can be adjusted precisely. Between the scenarios of random mixture (glassy state) and complete phase separation, conditions could be realized to facilitate the occurrence of various periodic structures in a single experiment. Some of these structures can only be explained by a dynamic, nonequilibrium and dissipative state. Eventually, the formation of certain metastable lattices can be interpreted as an emergent, systemic phenomenon. Thus, centrifugation can be used for studying the chaos-order transition in complex particle systems. PMID:26165700

  9. Hemocompatibility of a hydrodynamic levitation centrifugal blood pump.

    PubMed

    Yamane, Takashi; Maruyama, Osamu; Nishida, Masahiro; Kosaka, Ryo; Sugiyama, Daisuke; Miyamoto, Yusuke; Kawamura, Hiroshi; Kato, Takahisa; Sano, Takeshi; Okubo, Takeshi; Sankai, Yoshiyuki; Shigeta, Osamu; Tsutsui, Tatsuo

    2007-01-01

    A noncontact type centrifugal pump without any complicated control or sensing modules has been developed as a long-term implantable artificial heart. Centrifugal pumps with impellers levitated by original hydrodynamic bearings were designed and have been modified through numerical analyses and in vitro tests. The hemolysis level was reduced by changing the pressure distribution around the impeller and subsequently expanding the bearing gap. Thrombus formation in the bearing was examined with in vitro thrombogenesis tests and was reduced by changing the groove shapes to increase the bearing-gap flow to 3% of the external flow. Unnecessary vortices around the vanes were also eliminated by changing the number of vanes from four to six. PMID:17574508

  10. Centrifugal pump performance drop due to leading edge cavitation

    NASA Astrophysics Data System (ADS)

    Li, X. J.; Pan, Z. Y.; Zhang, D. Q.; Yuan, S. Q.

    2012-11-01

    This paper deals with the leading edge cavitation of the impeller of a single stage centrifugal pump. A centrifugal pump with and without inducer is investigated by numerical simulation. The simulation results of the pump with inducer were compared with experimental data under cavitating and non-cavitating situation. An acceptable agreement has been obtained for the overall performance. Cavitation phenomena are found in varied area near the impeller inlet at the condition in the impeller flow passage and induce unexpected head drop and blade load for the pump without inducer. Violent excitement of cavitation appears at conditions of low partial flow rate and low inlet pressure. As to that with inducer, through obvious cavitation occurs in the inducer passage, no violent cavitation is found in the impeller passage. The overall performance curves are also different between the two conditions.

  11. Experiment of a centrifugal pump during changing speed operation

    NASA Astrophysics Data System (ADS)

    Yuan, H. J.; Shao, J.; Wu, Y. L.; Liu, S. H.

    2012-11-01

    In this paper, a method of changing rotational speed of impeller periodically as the pulsatile working condition is developed to realize pulse outputs both of flow discharge and of head for a centrifugal pump through experiment. The performance of the centrifugal pump under pulsatile working operation condition is measured which indicates this model pump could produce desired pulse flow under such condition. Flow patterns at four testing points under pulsatile conditions are obtained by means of the particle image velocimetry (PIV) technology both with laser induced fluorescence (LIF) particles and refractive index matched (RIM) fluid. Results of PIV measurement show the distributions of velocity, streamlines, and the principal Reynolds normal stress (PRNS). Under the design flow rate condition, the relative velocity in the blade channel distributes smoothly and decreases from inlet to exit. And at the impeller exit, the relative velocity is lower close to suction side than that near pressure side of blade in most of blade channels.

  12. Core temperature of tailless rats exposed to centrifugation

    NASA Technical Reports Server (NTRS)

    Monson, C. B.; Oyama, J.

    1984-01-01

    The role of the tail in the altered thermoregulation of rats during acute exposure to hypergravity was investigated, using groups of rats of two ages: 55 days (young) and 138 days (old). Rectal and foot temperature changes were measured in intact and tailless rats subjected to 1 h centrifugation of 2.8 G, with preceding (1 h) and following (1-3 h) 1 G periods. At 22 C, the loss of body heat from the tail per se does not measurably contribute to the hypothermia induced by hypergravity. However, the heat loss from the feet was greater in the tailless rats than in the intact rats from the young group of animals, although there was no significant difference between the tailless and intact rats in the old animal group. It is concluded that the inhibition of heat production is a significant factor in the hypothermia of centrifuged tailless rats, as it has been previously shown to be in the intact animals.

  13. Predicting tonal noise from a high rotational speed centrifugal fan

    NASA Astrophysics Data System (ADS)

    Khelladi, S.; Kouidri, S.; Bakir, F.; Rey, R.

    2008-06-01

    Prediction of noise generated by centrifugal fans is much more complex than prediction noise generated by axial fans. A complete, aerodynamic and aeroacoustic, investigation of the tonal noise of a high rotational speed centrifugal fan is proposed in this paper. The studied fan is made up of an impeller, a diffuser and a return channel. The purpose of this work is to understand the nature of noise generated within this type of machine. An aeroacoustic model based on the Ffowcs Williams and Hawkings equation is used to predict dipole and monopole tonal noises in the frequency domain. Showing the importance of the monopole source in this kind of fans constitutes the main contribution in these research tasks. A numerical simulation of the fluid flow validated by experiments, enables to obtain the fluctuating forces and normal velocity on the impeller and diffuser blades needed for the aeroacoustic computation.

  14. Probing biomechanical properties with a centrifugal force quartz crystal microbalance

    NASA Astrophysics Data System (ADS)

    Webster, Aaron; Vollmer, Frank; Sato, Yuki

    2014-10-01

    Application of force on biomolecules has been instrumental in understanding biofunctional behaviour from single molecules to complex collections of cells. Current approaches, for example, those based on atomic force microscopy or magnetic or optical tweezers, are powerful but limited in their applicability as integrated biosensors. Here we describe a new force-based biosensing technique based on the quartz crystal microbalance. By applying centrifugal forces to a sample, we show it is possible to repeatedly and non-destructively interrogate its mechanical properties in situ and in real time. We employ this platform for the studies of micron-sized particles, viscoelastic monolayers of DNA and particles tethered to the quartz crystal microbalance surface by DNA. Our results indicate that, for certain types of samples on quartz crystal balances, application of centrifugal force both enhances sensitivity and reveals additional mechanical and viscoelastic properties.

  15. Optimization of centrifugal pump cavitation performance based on CFD

    NASA Astrophysics Data System (ADS)

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

    2015-01-01

    In order to further improve the cavitation performance of a centrifugal pump, slots on impeller blade near inlet were studied and six groups of hydraulic model were designed. Base on cavitating flow feature inside a centrifugal pump, bubble growth and implosion are calculated from the Rayleigh-Plesset equation which describes the dynamic behavior of spherical bubble and RNG ?-epsilon model was employed to simulate and analyze the internal two-phase flow of the model pump under the same conditions. The simulation results show that slots on blade near inlet could improve the cavitation performance and cavitation performance improvement of the second group was more obvious. Under the same conditions, the pressure on the back of blade near inlet was higher than the pressure on the back of unmodified blade near inlet, and energy distribution in the flow channel between the two blades was more uniform with a small change of head.

  16. Reverse-Tangent Injection in a Centrifugal Compressor

    NASA Technical Reports Server (NTRS)

    Skoch, Gary J.

    2007-01-01

    Injection of working fluid into a centrifugal compressor in the reverse tangent direction has been invented as a way of preventing flow instabilities (stall and surge) or restoring stability when stall or surge has already commenced. The invention applies, in particular, to a centrifugal compressor, the diffuser of which contains vanes that divide the flow into channels oriented partly radially and partly tangentially. In reverse-tangent injection, a stream or jet of the working fluid (the fluid that is compressed) is injected into the vaneless annular region between the blades of the impeller and the vanes of the diffuser. As used here, "reverse" signifies that the injected flow opposes (and thereby reduces) the tangential component of the velocity of the impeller discharge. At the same time, the injected jet acts to increase the radial component of the velocity of the impeller discharge.

  17. On Disintegreation of Cometary Nuclei and Asteroids by Centrifugal Forces

    NASA Astrophysics Data System (ADS)

    Ksanfomality, Leonid V.

    2015-08-01

    Because rotation of celestial bodies creates centrifugal forces, it was conjectured that the dumbbell waist of some asteroids and cometary nuclei resulted from the action of these forces, and that the waist undergoes slow but continuous elongation, which should end in breaking the asteroid or cometary nucleus into fragments.The talk focuses on the destruction of asteroids and cometary nuclei, and specifically on the dynamic evolution of the nucleus of comet 103P/Hartley-2 and Itokawa asteroid. The results of the calculation show that the centrifugal force increases stronger than gravity in a narrower part of the nucleus, and the Hartley-2 nucleus is indeed in a state of approaching disintegration into two parts. The nucleus of comet Hartley-2 is a spectacular example of a celestial body in the process of observable destruction. In the case of no external disturbances, the two components of the celestial body will separate to a distance of less than 1 km. Asteroid Itokawa has an irregular shape, which makes it more difficult to approximate it with simple geometric shapes. Its length is so small that this asteroid could be displayed, for example, in Red Square in Moscow. The average density of Itokawa is 3 times the 103P/Hartley-2 density. The waist area resembles the waist of comet Hartley-2; seen in the middle of the asteroid. It was of interest to calculate stresses as in the case of cometary nuclei and to check to what extent the asteroid is stable with respect to centrifugal forces, especially because its rotation period is less by a factor of 1.5, while centrifugal forces under the same conditions are greater by a factor of 2.2.

  18. Body Weight Gain during Altered Gravity: Spaceflight, Centrifugation and Transitions

    NASA Technical Reports Server (NTRS)

    Wade, Charles E.; Harper, J. S.; Daunton, N. G.; Corcoran, M. L.; Morey-Holton, E.; Hargens, Alan R. (Technical Monitor)

    1995-01-01

    Gravity is a force that influences all living systems, and is often disregarded in the study of environment on growth and development. To assess the effect of gravity exposure on growth, immature rats (130-200 g) were evaluated during chronic altered gravity exposure and during transition between gravity fields. The effects of 14 days of spaceflight on body weight gain were evaluated (n=12) and compared to controls. Spaceflight did not affect weight gain. In 6 rats, the transition from spaceflight to 1 G showed a significant (p less than 0.05) post flight weight loss over 48 hr of 13 g compared to controls. Over subsequent days this loss was compensated for with no difference noted after 5 days. Exposure to hypergravity, 2 G for 16 days, was evaluated in groups of n=6 (Control; On Center Control (OCC); Centrifuged). With centrifugation or OCC there was a reduction in body weight within 24 hr. The OCC regained control weights within 13 days. The weight difference, 26 +/- 1 g, persisted with 2 G with no subsequent difference in weight gain over days 3-16 compared to controls; 3.7 +/- 0.1 versus 3.9 +/- 0.1 g/day respectively. Transition from centrifugation to 1 G resulted in a weight increase within 48 hours. Over 16 days the rate of gain was increased 3.1 +/- 0.1 g/day for centrifuge compared to 2.1 +/- 0.1 g/day for controls between Day 3 to 16. However, differences from control were still noted on Day 16. Transition from one gravity field to another causes acute changes in body weight. Transition to microgravity or 1 G, following the acute changes, results in adjustments to attain a normal weight. In hypergravity the acute reduction in body weight persist, but weight gain is normal. Transitioning from hypergravity to 1G results in an increased weight gain to compensate for the persistent reduction during exposure.

  19. Impeller for a moderate-flow centrifugal pump

    SciTech Connect

    Ryazanov, S.D.

    1985-07-01

    The author explains the problems in design that cause the inefficiency of conventional low-discharge centrifugal pumps. He then describes the design and operation of an impeller with improved energy characteristics. He concludes that the new design, intermediate between an impeller with cylindrical channels and the conventional impellers with straight vanes, makes it possible to expand the recommended adjustment range of the pump's delivery and to increase the pressure and efficiency by approximately 9%.

  20. At 1050 Gallery, Block 12, two centrifugal pumps, Buffalo Pumps, ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    At 1050 Gallery, Block 12, two centrifugal pumps, Buffalo Pumps, Buffalo, NY, driven by Allis Chalmers motors (size 3 HSO, head 230, 120 cpm, 1750, rpm, Impulse dia. 15) installed in the 1960s and used for water-cooling system for 230-kv cable; the cables have been removed and the pumps are not currently used. - Columbia Basin Project, Grand Coulee Dam & Franklin D. Roosevelt Lake, Across Columbia River, Southeast of Town of Grand Coulee, Grand Coulee, Grant County, WA

  1. Liquid rocket engine centrifugal flow turbopumps. [design criteria

    NASA Technical Reports Server (NTRS)

    1973-01-01

    Design criteria and recommended practices are discussed for the following configurations selected from the design sequence of a liquid rocket engine centrifugal flow turbopump: (1) pump performance including speed, efficiency, and flow range; (2) impeller; (3) housing; and (4) thrust balance system. Hydrodynamic, structural, and mechanical problems are addressed for the achievement of required pump performance within the constraints imposed by the engine/turbopump system. Materials and fabrication specifications are also discussed.

  2. Stability of centrifugal convection in a rotating pipe

    NASA Astrophysics Data System (ADS)

    Herrada, Miguel; Shtern, Vladimir

    2015-06-01

    This numerical study reveals that the thermal convection, induced by the axial gradient of temperature in a rotating pipe, suffers from the shear-layer instability if the Prandtl number, Pr, is small. As Pr increases, this instability is suppressed by the stable density stratification in the field of centrifugal force. In an annular pipe, the thermal instability develops for large Pr if a temperature of walls is prescribed. For a narrow annulus, these features agree with the known results for a planar flow driven by gravity and a horizontal gradient of temperature. It is shown here that the thermal instability does not develop if the walls are adiabatic. The centrifugal and Marangoni convection of a liquid, partially filling the pipe, also suffers from the shear-layer instability for small Pr and has no thermal instability. These features agree with the experiments for the planar flow performed by Kirdyashkin. The obtained results are of fundamental interest and can be relevant for the development of centrifugal heat exchangers.

  3. Human ocular counterrolling during roll-tilt and centrifugation.

    PubMed

    MacDougall, H G; Curthoys, I S; Betts, G A; Burgess, A M; Halmagyi, G M

    1999-05-28

    To test a hypothesis about how otoliths resolve roll-tilts from translations, we measured human ocular torsion position [ocular counterrolling (OCR)] to maintained linear acceleration stimuli. All subjects (n = 8) were tested in two conditions where the same magnitude of shear along an interaural axis was generated in one of two ways: either by roll-tilt on a tilt-chair in a 1-g environment, or by centripetal linear acceleration during constant velocity rotation 1 m from the axis of rotation on a fixed-chair human centrifuge. The interaural shear to the otoliths was the same for these two conditions, but the dorsoventral shear was different and for all eight subjects the OCR on the centrifuge was significantly greater than the torsion on the tilt-chair, although the resultant angle was in fact smaller on the centrifuge than on the tilt-chair. The results confirm that dorsoventral shear is important for determining OCR. The otoliths may resolve potential stimulus ambiguities between tilts and translations by virtue of the different patterns of interaural and dorsoventral shear that these stimuli generate. PMID:10372070

  4. IR photodissociation spectroscopy and theory of Au+(CO)n complexes: nonclassical carbonyls in the gas phase.

    PubMed

    Velasquez, J; Njegic, B; Gordon, M S; Duncan, M A

    2008-03-01

    Au+(CO)n complexes are produced in the gas phase via pulsed laser vaporization, expanded in a supersonic jet, and detected with a reflectron time-of-flight mass spectrometer. Complexes up to n = 12 are observed, with mass channels corresponding to the n = 2 and n = 4 showing enhanced intensity. To investigate coordination and structure, individual complexes are mass-selected and probed with infrared photodissociation spectroscopy. Spectra in the carbonyl stretching region are measured for the n = 3-7 species, but no photodissociation is observed for n = 1, 2 due to the strong metal cation-ligand binding. The carbonyl stretch in these systems is blue-shifted 50-100 cm-1 with respect to the free CO vibration (2143 cm-1), providing evidence that these species are so-called "nonclassical" metal carbonyls. Theory at the MP2 and CCSD(T) levels provides structures for these complexes and predicted spectra to compare to the experiment. Excellent agreement is obtained between experiment and theory, establishing that the n = 3 complex is trigonal planar and the n = 4 complex is tetrahedral. PMID:18266347

  5. Application of Momentum Transfer Theory for Ion and Electron Transport in Pure Gases and in Gas Mixtures

    SciTech Connect

    Jovanovic, 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 strengths 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.

  6. Structural exploration and Förster theory modeling for the interpretation of gas-phase FRET measurements: Chromophore-grafted amyloid-? peptides.

    PubMed

    Kulesza, Alexander; Daly, Steven; MacAleese, Luke; Antoine, Rodolphe; Dugourd, Philippe

    2015-07-14

    The distance-dependence of excitation energy transfer, e.g., being described by Förster theory (Förster resonance energy transfer (FRET)), allows the use of optical techniques for the direct observation of structural properties. Recently, this technique has been successfully applied in the gas phase. The detailed interpretation of the experimental FRET results, however, relies on the comparison with structural modeling. We therefore present a complete first-principles modeling approach that explores the gas-phase structure of chromophore-grafted peptides and achieves accurate predictions of FRET efficiencies. We apply the approach to amyloid-? 12-28 fragments, known to be involved in amyloid plaque formation connected to Alzheimer's disease. We sample structures of the peptides that are grafted with 5-carboxyrhodamine 575 (Rh575) and QSY-7 chromophores by means of replica-exchange molecular dynamics simulations upon an Amber-type forcefield parametrization as a function of the charge state. The generated ensembles provide chromophore-distance and -orientation distributions which are used with the spectral parameters of the Rh575/QSY-7 chromophores to model FRET-efficiencies for the systems. The theoretical values agree with the experimental average "action"-FRET efficiencies and motivate to use the herein reported parametrization, sampling, and FRET-modeling technique in future studies on the structural properties and aggregation-behavior of related systems. PMID:26178129

  7. Structural exploration and Förster theory modeling for the interpretation of gas-phase FRET measurements: Chromophore-grafted amyloid-? peptides

    NASA Astrophysics Data System (ADS)

    Kulesza, Alexander; Daly, Steven; MacAleese, Luke; Antoine, Rodolphe; Dugourd, Philippe

    2015-07-01

    The distance-dependence of excitation energy transfer, e.g., being described by Förster theory (Förster resonance energy transfer (FRET)), allows the use of optical techniques for the direct observation of structural properties. Recently, this technique has been successfully applied in the gas phase. The detailed interpretation of the experimental FRET results, however, relies on the comparison with structural modeling. We therefore present a complete first-principles modeling approach that explores the gas-phase structure of chromophore-grafted peptides and achieves accurate predictions of FRET efficiencies. We apply the approach to amyloid-? 12-28 fragments, known to be involved in amyloid plaque formation connected to Alzheimer's disease. We sample structures of the peptides that are grafted with 5-carboxyrhodamine 575 (Rh575) and QSY-7 chromophores by means of replica-exchange molecular dynamics simulations upon an Amber-type forcefield parametrization as a function of the charge state. The generated ensembles provide chromophore-distance and -orientation distributions which are used with the spectral parameters of the Rh575/QSY-7 chromophores to model FRET-efficiencies for the systems. The theoretical values agree with the experimental average "action"-FRET efficiencies and motivate to use the herein reported parametrization, sampling, and FRET-modeling technique in future studies on the structural properties and aggregation-behavior of related systems.

  8. Substitution effect on thermochemical properties of gas-phase tirapazamine by density functional theory

    NASA Astrophysics Data System (ADS)

    Ahmadinejad, Neda; Tari, Mostafa Talebi

    2015-11-01

    In this study, quantum chemical calculations using density functional theory (DFT) method B3LYP/6-311++G( d, p) was carried out to investigate the halogen groups substituent effect on the structure and thermochemical parameters of tirapazamine analogues such as 3-amino-1,2,4-benzotriazine-1-oxide and 3-amino-1,2,4-benzotriazine. It has been found that halogen (35Cl and 81Br) groups substituent leaded to different structural stabilities. The tirapazamine with chloro substituents has been referred to the most stable tirapazamine analogues based on the minimum energy of investigated compounds. In this study, the calculated values have been compared at different temperatures. The present calculation data were found to be a logical way in predicting the relative stability of tirapazamine analogues.

  9. Theory of charge transport in two-dimensional electron gas/noncentrosymmetric superconductor junction

    NASA Astrophysics Data System (ADS)

    Bai, Chunxu; Wang, Juntao; Jia, Shuanwen; Yang, Yanling

    2010-07-01

    Based on the extended Blonder-Tinkham-Klapwijk (BTK) approach, we have investigated the charge transport in two-dimensional electron gas/noncentrosymmetric superconductor (2DEG/NCS) junction. The effects of the Rashba spin-orbit coupling (RSOC) and the interface barrier on the conductance are taken into account. It is found that there is a peak of the conductance with the Rashba strength ? in 2DEG for the nonzero Rashba strength ? in NCS. The peak feature of the conductance can be tuned largely by the interface barrier. These phenomena are essentially different from those found in FM/NCS tunneling junctions where the zero bias conductance is suppressed by ?, independent of the barrier strength.

  10. Comment on "Kinetic theory for a mobile impurity in a degenerate Tonks-Girardeau gas"

    NASA Astrophysics Data System (ADS)

    Schecter, Michael; Gangardt, Dimitri M.; Kamenev, Alex

    2015-07-01

    In a recent paper Gamayun et al. [O. Gamayun, O. Lychkovskiy, and V. Cheianov, Phys. Rev. E 90, 032132 (2014), 10.1103/PhysRevE.90.032132] studied the dynamics of a mobile impurity weakly coupled to a one-dimensional Tonks-Girardeau gas of strongly interacting bosons. Employing the Boltzmann equation approach, they, in particular, arrived at the following conclusions: (i) a light impurity, being accelerated by a constant force F , does not exhibit Bloch oscillations, which were predicted and studied by Gangardt and co-workers [D. M. Gangardt and A. Kamenev, Phys. Rev. Lett. 102, 070402 (2009), 10.1103/PhysRevLett.102.070402; M. Schecter, D. M. Gangardt, and A. Kamanev, Ann. Phys. (N.Y.) 327, 639 (2012), 10.1016/j.aop.2011.10.001]; (ii) a heavy impurity does undergo Bloch oscillations, accompanied by a drift with the velocity vD??{F } . In this Comment we argue that result (i) is an artifact of the classical Boltzmann approximation. The latter misses the formation of the quasibound state between the impurity and a hole. Its dispersion relation Eb(P ,? ) is a smooth periodic function of momentum P with the period 2 kF=2 ? ? ? , where ? is a density of the host gas. Being accelerated by a small force, such a bound-state exhibits Bloch oscillations superimposed with the drift velocity vD=? F . The mobility ? may be expressed exactly [M. Schecter et al., Ann. Phys. (N.Y.) 327, 639 (2012), 10.1016/j.aop.2011.10.001] in terms of Eb(P ,? ) . Result (ii), while not valid at exponentially small forces, indeed reflects an interesting intermediate-force behavior.

  11. Comparative Analysis between Grundfos CRE 15-3 Variable Speed Centrifugal Pumps and a Worthington D-824 Constant Speed Centrifugal Pump in a KU Steam Power Plant Application

    E-print Network

    Schmidt, Fabian Philip

    2014-05-31

    This document presents a comparative analysis between the use of a Grundfos CRE 15-3 variable speed centrifugal pump and a Worthington D-824 constant speed centrifugal pump in a steam power plant application. This was performed since, in many...

  12. Centrifuge polarizing microscope. I. Rationale, design and instrument performance.

    PubMed

    Inoué, S; Knudson, R A; Goda, M; Suzuki, K; Nagano, C; Okada, N; Takahashi, H; Ichie, K; Iida, M; Yamanaka, K

    2001-03-01

    We first describe early uses of the centrifuge for deciphering physical properties and molecular organization within living cells, as well as the development and use of centrifuge microscopes for such studies. The rationale for developing a centrifuge microscope that allows high-extinction polarized light microscopy to observe dynamic fine structures in living cells is next discussed. We then describe a centrifuge polarizing microscope (CPM) that we developed for observing fine structural changes in living cells which are being exposed to up to approximately 11 500 times earth's gravitational field (g). With the specimen housed in a rotor supported on an air spindle motor, and imaged through an external microscope illuminated by a precisely synchronized flash of less than 10 ns duration from a Nd:YAG laser, the image of the spinning object remains steady up to the maximum speed of 11 700 rev min-1, or up to approximately 11 500 x g. The image is captured, at up to 25 frames s-1, by an interference-fringe-free CCD camera that is synchronized to the centrifuge rotor. At all speeds (in 100 rev min-1 increments), the image is resolved to better than 1 microm, while birefringence of the specimen, housed in a specially designed specimen chamber that suffers low-stress birefringence and prevents leakage of the physiological solutions, is detected with a retardance sensitivity of better than 1 nm. Differential interference contrast and fluorescence images (532 nm excitation) of the spinning specimen can also be generated with the CPM. The second part of this study (Inoué et al., J. Microsc. 201 (2001) 357-367, describes several biological applications of the CPM that we have explored. Individual live cells, such as oocytes and blood cells, are supported on a sucrose or Percoll density gradient while other cells, such as cultured fibroblasts and Dictyostelium amoebae, are observed crawling on glass surfaces. Observations of these cells exposed to the high G fields (centripetal acceleration/g) in the CPM are yielding many new results that lead to intriguing questions regarding the organization and function of fine structures in living cells and related quasi-fluid systems. PMID:11240850

  13. Water Drainage from Unsaturated Soils in a Centrifuge Permeameter

    NASA Astrophysics Data System (ADS)

    Ornelas, G.; McCartney, J.; Zhang, M.

    2013-12-01

    This study involves an analysis of water drainage from an initially saturated silt layer in a centrifuge permeameter to evaluate the hydraulic properties of the soil layer in unsaturated conditions up to the point where the water phase becomes discontinuous. These properties include the soil water retention curve (SWRC) and the hydraulic conductivity function (HCF). The hydraulic properties of unsaturated silt are used in soil-atmosphere interaction models that take into account the role of infiltration and evaporation of water from soils due to atmospheric interaction. These models are often applied in slope stability analyses, landfill cover design, aquifer recharge analyses, and agricultural engineering. The hydraulic properties are also relevant to recent research concerning geothermal heating and cooling, as they can be used to assess the insulating effects of soil around underground heat exchangers. This study employs a high-speed geotechnical centrifuge to increase the self-weight of a compacted silt specimen atop a filter plate. Under a centrifuge acceleration of N times earth's gravity, the concept of geometric similitude indicates that the water flow process in a small-scale soil layer will be similar to those in a soil layer in the field that is N times thicker. The centrifuge acceleration also results in an increase in the hydraulic gradient across the silt specimen, which causes water to flow out of the pores following Darcy's law. The drainage test was performed until the rate of liquid water flow out of the soil layer slowed to a negligible level, which corresponds to the transition point at which further water flow can only occur due to water vapor diffusion following Fick's law. The data from the drainage test in the centrifuge were used to determine the SWRC and HCF at different depths in the silt specimen, which compared well with similar properties defined using other laboratory tests. The transition point at which liquid water flow stopped (and Darcy's law is no longer valid) was at a relatively high degree of saturation of 0.8. This finding is important as many water flow analyses in the literature assume that Darcy's law is valid over a much wider range of degrees of saturation, an error that potentially may lead to overestimates of water flow in unsaturated soil layers.

  14. 75 FR 61461 - Central New York Oil and Gas Company, LLC; Notice of Availability of the Environmental Assessment...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-10-05

    ...electric-driven 15,300-hp centrifugal compressor; Two 30-inch-diameter natural gas pipelines, each about 820 feet long, connecting the NS2 Compressor Station with Tennessee Gas Pipeline Company's (TGP)...

  15. The NATA code: Theory and analysis, volume 1. [user manuals (computer programming) - gas dynamics, wind tunnels

    NASA Technical Reports Server (NTRS)

    Bade, W. L.; Yos, J. M.

    1975-01-01

    A computer program for calculating quasi-one-dimensional gas flow in axisymmetric and two-dimensional nozzles and rectangular channels is presented. Flow is assumed to start from a state of thermochemical equilibrium at a high temperature in an upstream reservoir. The program provides solutions based on frozen chemistry, chemical equilibrium, and nonequilibrium flow with finite reaction rates. Electronic nonequilibrium effects can be included using a two-temperature model. An approximate laminar boundary layer calculation is given for the shear and heat flux on the nozzle wall. Boundary layer displacement effects on the inviscid flow are considered also. Chemical equilibrium and transport property calculations are provided by subroutines. The code contains precoded thermochemical, chemical kinetic, and transport cross section data for high-temperature air, CO2-N2-Ar mixtures, helium, and argon. It provides calculations of the stagnation conditions on axisymmetric or two-dimensional models, and of the conditions on the flat surface of a blunt wedge. The primary purpose of the code is to describe the flow conditions and test conditions in electric arc heated wind tunnels.

  16. Kinetic theory of cavity cooling and self-organisation of a cold gas

    E-print Network

    Wolfgang Niedenzu; Tobias Grießer; Helmut Ritsch

    2011-11-04

    We study spatial self-organisation and dynamical phase-space compression of a dilute cold gas of laser-illuminated polarisable particles in an optical resonator. Deriving a non-linear Fokker--Planck equation for the particles' phase-space density allows us to treat arbitrarily large ensembles in the far-detuning limit and explicitly calculate friction forces, momentum diffusion and steady-state temperatures. In addition, we calculate the self-organisation threshold in a self-consistent analytic form. For a homogeneous ensemble below threshold the cooling rate for fixed laser power is largely independent of the particle number. Cooling leads to a $q$-Gaussian velocity distribution with a steady-state temperature determined by the cavity linewidth. Numerical simulations using large ensembles of particles confirm the analytical threshold condition for the appearance of an ordered state, where the particles are trapped in a periodic pattern and can be cooled to temperatures close to a single vibrational excitation.

  17. 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 or are taking CHEM 203 or CHEM 204. Note: Chemistry Honours and Majors must take CHEM 223 and CHEM 253 edition (Pearson Education, Inc., 2013). J.R. Barrante, Applied Mathematics for Physical Chemistry, 3rd

  18. Research on energy conversion mechanism of a screw centrifugal pump under the water

    NASA Astrophysics Data System (ADS)

    Quan, H.; Li, R. N.; Su, Q. M.; Han, W.; Cheng, X. R.; Shen, Z. J.

    2013-12-01

    In order to research screw centrifugal pump impeller power capability and energy conversion mechanism, we used Navier-Stokes equation and standard k-? equation turbulence model on the basis of the Euler equations to carry out screw centrifugal pump internal flow numerical simulation. This was explored by simulating specific design conditions; the medium is water, variation of speed and pressure of flow filed under the action of the impeller, and the screw centrifugal impeller shroud line and wheel line segment take monitoring sites. The monitoring points are between dynamic head and static head change to analyze the energy conversion capability along the impeller corners of screw centrifugal pump. The results show that the energy of fluid of the screw centrifugal pump is provided by spiral segment, the spiral segment in front of the impeller has played a multi-level role, it has significant reference value to research the energy conversion mechanism of screw centrifugal pump under solid-liquid two phase.

  19. A human-powered, small radius centrifuge for space application: a design study.

    PubMed

    Meeker, L J; Isdahl, W M; Helduser, J W

    1996-01-01

    The necessity of preventing physiologic deconditioning of astronauts exposed to long duration space flights is well known. A method under consideration to prevent this deconditioning is the use of periodic exposure to artificial gravity which could be provided by a centrifuge. This paper presents a design study for a human-powered centrifuge which could be used aboard the NASA Space Shuttle with analyses which quantify many of the forces produced. Consideration is given to managing reaction forces to changes in centrifuge angular velocity, centrifuge imbalance effects, the effects of gyroscopic moment on spacecraft orientation changes, and torque and power requirements as a function of centrifuge performance parameters. A design concept for a "human powered" centrifuge which could provide both exercise and artificial gravity exposure is also considered. PMID:11539367

  20. Influence of blade angle distribution along leading edge on cavitation performance of a centrifugal pump

    NASA Astrophysics Data System (ADS)

    Xu, Y.; Tan, L.; Cao, S. L.; Wang, Y. C.; Meng, G.; Qu, W. S.

    2015-01-01

    The influence of blade angle distribution along leading edge on cavitation performance of centrifugal pumps is analysed in the present paper. Three sets of blade angle distribution along leading edge for three blade inlet angles are chosen to design nine centrifugal pump impellers. The RNG k-epsilon turbulence model and the Zwart-Gerber-Belamri cavitation model are employed to simulate the cavitation flows in centrifugal pumps with different impellers and the same volute. The numerical results are compared with the experimental data, and the comparison proves that the numerical simulation can accurately predict the cavitation performance of centrifugal pumps. On the basis of the numerical simulations, the pump head variations with pump inlet pressure, and the flow details in centrifugal pump are revealed to demonstrate the influence of blade angle distribution along leading edge on cavitation performances of centrifugal pumps.

  1. A Centrifuge-Based Technique for Dry Extraction of Air for Ice Core Studies of Carbon Dioxide.

    NASA Astrophysics Data System (ADS)

    Grachev, A. M.; Brook, E. J.

    2008-12-01

    High resolution CO2 data from the Law Dome ice core document an abrupt ~10 ppm drop in CO2 at about 1600 AD (MacFarling Meure et al., Geophys. Res Lett., v. 33, L14810), which has been attributed to changes in human activities. CO2 measurements in ice cores are difficult, however, making verification of this feature an important task. We are undertaking a high-resolution study of CO2 between 1400 and 1800 AD in the WAIS Divide (Antarctica) ice core with a new dry extraction technique. The need for a dry extraction technique as opposed to a melt-refreeze technique in studies of CO2 from ice cores arises because of the well-documented artifacts in CO2 imposed by the presence of liquid water. Three dry-extraction methods have been employed by previous workers to measure CO2: needle-crushing method, ball-bearings method, and cheese-grater method (B. Stauffer, in: Encyclopedia of Quaternary Science, p. 1181, Elsevier 2007). Each has limitations, and we propose a simpler dry extraction technique, based on a large-capacity refrigerated centrifuge (the "centrifuge technique"), which eliminates the need to employ cryogenic temperatures to collect extracted gas and is more compatible with high sample throughput. The technique is now being tested on ~25-gram WAIS Divide samples in conjunction with CO2 measurements with a gas chromatograph. The technique employs a Beckman J- 6B centrifuge, in which evacuated stainless steel flask is placed: the flask has a weight inside positioned directly over a tall-standing piece of ice whose cross-section is small compared to that of the flask. Upon acceleration to 3000 rpm the weight moves down and presses the ice sample into a thin tablet covering flask's bottom, yielding the air extraction efficiency of ~80%. Preliminary tests suggest that precision and accuracy can be achieved at the level of ~1 ppm once the system is fine-tuned.

  2. 40 CFR Appendix - Alternative Organic HAP Emissions Limits for Open Molding, Centrifugal Casting, and SMC...

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... casting—CR/HS 3,4 A vent system that moves heated air through the mold 27 lb/ton. 8. Centrifugal casting—non-CR/HS 3,4 A vent system that moves heated air through the mold 21 lb/ton. 7. Centrifugal casting—CR/HS 3,4 A vent system that moves ambient air through the mold 2 lb/ton. 8. Centrifugal...

  3. 40 CFR Appendix - Alternative Organic HAP Emissions Limits for Open Molding, Centrifugal Casting, and SMC...

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... casting—CR/HS 3,4 A vent system that moves heated air through the mold 27 lb/ton. 8. Centrifugal casting—non-CR/HS 3,4 A vent system that moves heated air through the mold 21 lb/ton. 7. Centrifugal casting—CR/HS 3,4 A vent system that moves ambient air through the mold 2 lb/ton. 8. Centrifugal...

  4. 40 CFR Appendix - Alternative Organic HAP Emissions Limits for Open Molding, Centrifugal Casting, and SMC...

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... casting—CR/HS 3,4 A vent system that moves heated air through the mold 27 lb/ton. 8. Centrifugal casting—non-CR/HS 3,4 A vent system that moves heated air through the mold 21 lb/ton. 7. Centrifugal casting—CR/HS 3,4 A vent system that moves ambient air through the mold 2 lb/ton. 8. Centrifugal...

  5. On the inverse problem of blade design for centrifugal pumps and fans

    NASA Astrophysics Data System (ADS)

    Kruyt, N. P.; Westra, R. W.

    2014-06-01

    The inverse problem of blade design for centrifugal pumps and fans has been studied. The solution to this problem provides the geometry of rotor blades that realize specified performance characteristics, together with the corresponding flow field. Here a three-dimensional solution method is described in which the so-called meridional geometry is fixed and the distribution of the azimuthal angle at the three-dimensional blade surface is determined for blades of infinitesimal thickness. The developed formulation is based on potential-flow theory. Besides the blade impermeability condition at the pressure and suction side of the blades, an additional boundary condition at the blade surface is required in order to fix the unknown blade geometry. For this purpose the mean-swirl distribution is employed. The iterative numerical method is based on a three-dimensional finite element method approach in which the flow equations are solved on the domain determined by the latest estimate of the blade geometry, with the mean-swirl distribution boundary condition at the blade surface being enforced. The blade impermeability boundary condition is then used to find an improved estimate of the blade geometry. The robustness of the method is increased by specific techniques, such as spanwise-coupled solution of the discretized impermeability condition and the use of under-relaxation in adjusting the estimates of the blade geometry. Various examples are shown that demonstrate the effectiveness and robustness of the method in finding a solution for the blade geometry of different types of centrifugal pumps and fans. The influence of the employed mean-swirl distribution on the performance characteristics is also investigated.

  6. Centrifuge facility conceptual system study. Volume 2: Facility systems and study summary

    NASA Technical Reports Server (NTRS)

    Synnestvedt, Robert (editor); Blair, Patricia; Cartledge, Alan; Garces-Porcile, Jorge; Garin, Vladimir; Guerrero, Mike; Haddeland, Peter; Horkachuck, Mike; Kuebler, Ulrich; Nguyen, Frank

    1991-01-01

    The Centrifuge Facility is a major element of the biological research facility for the implementation of NASA's Life Science Research Program on Space Station Freedom using nonhuman species (small primates, rodents, plants, insects, cell tissues, etc.). The Centrifuge Facility consists of a variable gravity Centrifuge to provide artificial gravity up to 2 earth G's' a Holding System to maintain specimens at microgravity levels, a Glovebox, and a Service Unit for servicing specimen chambers. The following subject areas are covered: (1) Holding System; (2) Centrifuge System; (3) Glovebox System; (4) Service System; and (5) system study summary.

  7. Alloy 20 centrifugal pumps corrosion-free with sulfuric acid

    SciTech Connect

    Miller, R.; Ormond, D.L.

    1986-09-01

    General Battery Corporation manufactures an extensive line of lead-acid batteries for trucks, automobiles, motorcycles, electric-powered vehicles and lighting systems in eight eastern, mid-western and west coast plants. The plant in Hamburg, PA, which produces the most diversified line of batteries, was storing 66/sup 0/ Baume sulfuric acid in tanks located 30' overhead. The concentrated acid flows by gravity to four cutting tanks for dilution with pure water to reduce the specific gravity (sp gr). The dilute 1.100-1.400 sp gr sulfuric acid was being transferred from the cutting tanks to production lines, or to recycle storage tanks, by three centrifugal pumps. The three pumps required frequent, costly maintenance or replacement, usually because of corroded casings and impellers. A fourth pump was kept as a reserve unit to replace one that failed. A more reliable pump was badly needed, especially since future plant expansions and changes in the acid handling system would require additional pumps. Centrifugal pumps from various vendors were investigated for corrosion resistance, performance and projected maintenance requirements. An ANSI standard dimension process pump with rugged casing and impeller of corrosion resistant alloy 20 was elected for the acid-test, replacing one of the three pumps in dilute acid distribution service. The nine alloy 29, ANSI standard centrifugal pumps significantly reduced acid transfer costs by eliminating the need to replace corroded components. The same pump is being considered for acid service in other General Battery plants as a result of the reliable performance and minimal maintenance requirements.

  8. Design considerations of volute geometry of a centrifugal blood pump.

    PubMed

    Chan, Weng Kong; Wong, Yew Wah; Hu, Wei

    2005-12-01

    This article compares two different design techniques that are conventionally used in the design of volutes for centrifugal pumps. The imbalanced forces due to the geometry of the volute need to be taken into consideration especially in centrifugal blood pumps with magnetically suspended impeller. A reduction of these forces can reduce the instability of the impeller motion as well as the power needed to counteract its influence. Volutes using the constant angular momentum (CAM) and the constant mean velocity (CMV) methods were developed and modeled numerically. The computational results on the effect of volute geometry on the performance of a centrifugal blood pump impeller for six different volutes are presented here. For volutes designed using the CAM method, model B (volute expansion angle of 3 degrees ) had the lowest radial force of 0.26 N while the pressure head generated was 12,900 Pa. For volutes designed using the CMV method, model F (1.6 m/s) had the lowest imbalanced force of 0.45 N. However, the pressure developed by this pump was also one of the lowest at 10,652 Pa. Furthermore, when the peak scalar stresses and the mean exposure time of particles for all designs were determined using Lagrangian particle tracking method, it was observed that in general, the peak scalar stresses in CAM designed volutes are lower than those designed using CMV method. The mean exposure time of particles in the pump ranged from 400 to 500 ms. The simulation results showed that the volute designed using CAM method was superior to that of a CMV volute in terms of the magnitude of the radial force and the peak scalar stresses for the same pressure head generated. Results show that the design of volutes for blood pumps should go beyond conventional empirical methods to obtain optimal results. PMID:16305649

  9. Aneutronic fusion on the base of asymmetrical centrifugal trap

    NASA Astrophysics Data System (ADS)

    Volosov, V. I.

    2006-08-01

    A physical design of a device that can be a base for a direct-conversion nuclear electric power station is considered. The project considers the aneutronic reaction P-11B in the asymmetric centrifugal trap. Kinetic energy of nuclear particles (alpha particles) is converted into electrical energy inside this device; no thermal cycle is used. Heating and recuperation of energy of protons and boron ions take place in the plasma space. The presented scheme differs significantly from the conventional thermonuclear fusion. 'Fast' protons, which are the main energy component of plasma, have an almost monoenergetic spectrum. This makes it possible to realize the 'resonance' fusion.

  10. Oxygen consumption measurements during continual centrifugation of mice.

    NASA Technical Reports Server (NTRS)

    Fethke, W.; Cook, K. M.; Porter, S. M.; Wunder, C. C.

    1973-01-01

    A simple method is described for measurement of metabolism of conscious, unrestrained animals, during chronic centrifugation or other conditions of isolation (23.75 hr/day) from the investigators in an essentially normal atmospheric environment for as long as seven days. This involves telemetry of pressure changes in a metabolic chamber. At 7 G's, increased O2 intake lasting two to seven days and a decreased excursion of the day-night difference were measured for male white mice with less effect or even an opposite effect at lower fields. Base-line measurements of metabolic rate per mouse are less affected by animal size than expected from the surface area law.

  11. Analyses of hydrodynamic radial forces on centrifugal pump impellers

    NASA Technical Reports Server (NTRS)

    Adkins, D. R.; Brennen, C. E.

    1988-01-01

    An experimental and theoretical study of the hydrodynamic interactions occurring between a centrifugal pump impeller and a volute is presented. The theoretical analysis provides a quasi-one-dimensional treatment of the flow in the volute, and it is extended to include the hydrodynamic force perturbations caused by the impeller whirling eccentrically in the volute. It is noted that these perturbations are often destabilizing. The theoretical models were found to accurately predict the radial forces caused by the flow through the impeller. The pressure acting on the front shroud of the impeller is shown to have a significant effect on the destabilizing hydrodyamic forces.

  12. Pumping stage for multi-stage centrifugal pump

    SciTech Connect

    Erickson, J.W.

    1981-07-14

    An improved diffusion bowl and pumping vanes of a centrifugal pump stage are employed in axially stacked, multi-stage pumps for use in oil wells. The wall thickness of the annular casing portion of the diffusion bowl element is reduced to a minimum consistent with the axial loading on the pump stage and the impeller vanes are radially extended to terminate closely adjacent the minimum wall thickness portion of the casing, thereby significantly increasing the pumping pressure developed by the stage without reducing the efficiency of the stage.

  13. Effect of Centrifugal Transverse Wakefield for Microbunch in Bend

    SciTech Connect

    Stupakov, G.V.; /SLAC

    2006-03-22

    We calculate centrifugal force for a short bunch in vacuum moving in a circular orbit and estimate the emittance growth of the beam in a bend due to this force. Many of the basic features of the coherent synchrotron radiation (CSR) of short bunches and its effect on beam dynamics in accelerators are now well established. The effect is usually described in terms of the longitudinal force, or wakefield, that causes the energy loss in the beam, and also redistributes the energy between the particles by accelerating the head and decelerating the tail of the bunch. Coherent radiation becomes most important for short bunches and high currents. More subtle features of CSR such as transition effect due to the entrance to and exit from the bend, CSR force in the undulator, and shielding due to the close metallic boundaries have been also studied. Much less is known about the transverse force in a short bunch moving on a circular orbit. The problem has been treated in several papers beginning from R. Talman's work, who pointed out that the centrifugal force of a rotating bunch can result in a noticeable tune shift of betatron oscillations. Later, an important correction to the Talman paper has been added, where it was shown that due to the energy variation in the bunch, the effect of the transverse force proportional to R{sup -1} is canceled, and the residual effect is of the order of R{sup -2}, that is much smaller than originally predicted. Recently, however, Derbenev and Shiltsev found the centrifugal force of the order of R{sup -1} that differs from Talman's result by a logarithmic factor only. Taking into account the existing controversy in the literature, in this paper, we consider the transverse force in a bunch based on simple physical arguments, starting from a dc beam. We will derive the centrifugal force for a relativistic coasting beam in vacuum, and then generalize the result for a short bunch, and estimate its effect on the emittance growth in a bend. Throughout this paper we assume ultrarelativistic beam, v = c, moving on a circular orbit of radius R.

  14. Centrifuge-operated specimen staining method and apparatus

    NASA Technical Reports Server (NTRS)

    Clarke, Mark S. F. (Inventor); Feeback, Daniel L. (Inventor)

    1999-01-01

    A method of staining preselected, mounted specimens of either biological or nonbiological material enclosed within a staining chamber where the liquid staining reagents are applied and removed from the staining chamber using hypergravity as the propelling force. In the preferred embodiment, a spacecraft-operated centrifuge and method of diagnosing biological specimens while in orbit, characterized by hermetically sealing a shell assembly. The assembly contains slide stain apparatus with computer control therefor, the operative effect of which is to overcome microgravity, for example on board an International Space Station.

  15. Gender Differences in Cardiovascular Tolerance to Short Arm Centrifugation

    NASA Technical Reports Server (NTRS)

    Fong, Kevin J.; Arya, Maneesh; Paloski, William H.

    2007-01-01

    In preparation for the NASA Artificial Gravity (AG) pilot study, the tolerability of the proposed AG parameters was tested in 11 ambulatory human subjects (6m, 5w) by exposing each to a short arm centrifuge trial. Subjects were oriented in the supine position (but inclined 6deg head down) on one arm of the centrifuge, and the rotation rate (30.6-33.4 rpm) and radial position of the feet were set to produce 2.5G of equivalent gravitational load at the force plate directly beneath the feet, 1G at the level of the mediastinum, and approximately 0.55G at the labyrinth. Amongst the 6 men participating in this preliminary study, 5 completed at least 60 minutes of the trial successfully with no adverse sequelae. However, amongst the female cohort the test was stopped by the medical monitor before 60 min in all but one case, with pre-syncope listed as the reason for termination in all cases. Mean time before abort of the centrifuge run amongst the women was 33.2 +/- 20.97 min. It is known that women have a greater predisposition to syncope during orthostatic stress, under normal tilt table conditions, during LBNP, and following space flight. The reasons for this difference are the subject of some debate, but anthropometric factors, the vasoactive effects of sex hormones, gender differences in susceptibility to motion sickness, catecholamine levels, ability to augment total peripheral resistance in response to orthostatic stress, and structural differences in cardiac anatomy and physiology have all been suggested. This finding led to the exclusion of women from the AG pilot study. Clearly if AG is to be employed as a multi-system countermeasure it must provide physiological protection at rotation rates within the tolerance limits of all potential astronauts. Further investigation of the responses of women to centrifugation will be necessary to determine how to adjust AG parameters for tolerance by female subjects before a more detailed investigation of the appropriate dose in terms of G load, rotation rate, exposure duration and frequency can be performed.

  16. Centrifugal acceleration of ions in the polar magnetosphere

    NASA Technical Reports Server (NTRS)

    Swinney, Kenneth R.; Horwitz, James L.; Delcourt, D.

    1987-01-01

    The transport of ionospheric ions originating near the dayside cusp into the magnetotail is parametrically studied using a 3-D model of ion trajectories. It is shown that the centrifugal term in the guiding center parallel force equation dominates the parallel motion after about 4 Re geocentric distance. The dependence of the equatorial crossing distance on initial latitude, energy and convection electric field is presented for ions originating on the dayside ionosphere in the noon-midnight plane. It is also found that up to altitudes of about 5 Re, the motion is similar to that of a bead on a rotating rod, for which a simple analytical solution exists.

  17. Centrifuge modeling of rocking-isolated inelastic RC bridge piers

    PubMed Central

    Loli, Marianna; Knappett, Jonathan A; Brown, Michael J; Anastasopoulos, Ioannis; Gazetas, George

    2014-01-01

    Experimental proof is provided of an unconventional seismic design concept, which is based on deliberately underdesigning shallow foundations to promote intense rocking oscillations and thereby to dramatically improve the seismic resilience of structures. Termed rocking isolation, this new seismic design philosophy is investigated through a series of dynamic centrifuge experiments on properly scaled models of a modern reinforced concrete (RC) bridge pier. The experimental method reproduces the nonlinear and inelastic response of both the soil-footing interface and the structure. To this end, a novel scale model RC (1:50 scale) that simulates reasonably well the elastic response and the failure of prototype RC elements is utilized, along with realistic representation of the soil behavior in a geotechnical centrifuge. A variety of seismic ground motions are considered as excitations. They result in consistent demonstrably beneficial performance of the rocking-isolated pier in comparison with the one designed conventionally. Seismic demand is reduced in terms of both inertial load and deck drift. Furthermore, foundation uplifting has a self-centering potential, whereas soil yielding is shown to provide a particularly effective energy dissipation mechanism, exhibiting significant resistance to cumulative damage. Thanks to such mechanisms, the rocking pier survived, with no signs of structural distress, a deleterious sequence of seismic motions that caused collapse of the conventionally designed pier. © 2014 The Authors Earthquake Engineering & Structural Dynamics Published by John Wiley & Sons Ltd. PMID:26300573

  18. Effect of Speed (Centrifugal Load) on Gear Crack Propagation Direction

    NASA Technical Reports Server (NTRS)

    Lewicki, David G.

    2001-01-01

    The effect of rotational speed (centrifugal force) on gear crack propagation direction was explored. Gears were analyzed using finite element analysis and linear elastic fracture mechanics. The analysis was validated with crack propagation experiments performed in a spur gear fatigue rig. The effects of speed, rim thickness, and initial crack location on gear crack propagation direction were investigated. Crack paths from the finite element method correlated well with those deduced from gear experiments. For the test gear with a backup ratio (rim thickness divided by tooth height) of nib = 0.5, cracks initiating in the tooth fillet propagated to rim fractures when run at a speed of 10,000 rpm and became tooth fractures for speeds slower than 10,000 rpm for both the experiments and anal sis. From additional analysis, speed had little effect on crack propagation direction except when initial crack locations were near the tooth/rim fracture transition point for a given backup ratio. When at that point, higher speeds tended to promote rim fracture while lower speeds (or neglecting centrifugal force) produced tooth fractures.

  19. Methodology for optimally sized centrifugal partition chromatography columns.

    PubMed

    Chollet, Sébastien; Marchal, Luc; Jérémy Meucci; Renault, Jean-Hugues; Legrand, Jack; Foucault, Alain

    2015-04-01

    Centrifugal Partition Chromatography (CPC) is a separation process based on the partitioning of solutes between two partially miscible liquid phases. There is no solid support for the stationary phase. The centrifugal acceleration is responsible for both stationary phase retention and mobile phase dispersion. CPC is thus a process based on liquid-liquid mass transfer. The separation efficiency is mainly influenced by the hydrodynamics of the phases in each cell of the column. Thanks to a visualization system, called "Visual CPC", it was observed that the mobile phase can flow through the stationary phase as a sheet, or a spray. Hydrodynamics, which directly governs the instrument efficiency, is directly affected during scale changes, and non-linear phenomena prevent the successful achievement of mastered geometrical scale changes. In this work, a methodology for CPC column sizing is proposed, based on the characterization of the efficiency of advanced cell shapes, taking into account the hydrodynamics. Knowledge about relationship between stationary phase volume, cell efficiency and separation resolution in CPC allowed calculating the optimum cell number for laboratory and industrial scale CPC application. The methodology is highlighted with results on five different geometries from 25 to 5000 mL, for two applications: the separation of alkylbenzene by partitioning with heptane/methanol/water biphasic system; and the separation of peptides by partitioning with n-butanol/acetic acid/water (4/1/5) biphasic system. With this approach, it is possible to predict the optimal CPC column length leading to highest productivity. PMID:25744547

  20. Extraction of phenol in wastewater with annular centrifugal contactors.

    PubMed

    Xu, Jin-Quan; Duan, Wu-Hua; Zhou, Xiu-Zhu; Zhou, Jia-Zhen

    2006-04-17

    Solvent extraction is an effective way to treat and recover the phenolic compounds from the high content phenolic wastewater at present. The experimental study on treating the wastewater containing phenol has been carried out with QH-1extractant (the amine mixture) and annular centrifugal contactors. The distribution ratio of phenol was 108.6 for QH-1-phenol system. The mass-transfer process of phenol for the system was mainly controlled by diffusion. When the flow ratio (aqueous/organic) was changed from 1/1 to 4/1, the rotor speed was changed from 2500 to 4000 r/min, and the total flow of two phases was changed from 20 to 70 mL/min, the mass-transfer efficiency E of the single-stage centrifugal contactor was more than 95%. When the flow ratio was changed from 4.4/1 to 4.9/1, the rotor speed was 3000 r/min, and the total flow of two phases was changed from 43.0 to 47.0 mL/min, the extraction rate rho of the three-stage cascade was more than 99%. When 15% NaOH was used for stripping of phenol in QH-1, the stripping efficiency of the three-stage cascade was also more than 99% under the experimental conditions. PMID:16225989

  1. Pretreatment of industrial wastewater containing phthalate esters by centrifugation

    SciTech Connect

    Petrosky, C.J.; Vidic, R.D.

    1996-11-01

    In this study, a full-scale commercial centrifuge was used to treat, on a continuous basis, the entire wastewater stream generated by a chemical manufacturing facility which produces a variety of phthalate, adipate, maleate, and trimellitate esters. The wastewater from this facility is comprised of process water, equipment was water, and rain water runoff containing varying concentrations of bis(2-ethylhexyl) phthalate (BEHP), di-n-octyl phthalate (DNOP), and di-n-butyl phthalate (DNBP) esters in addition to mono-ester salts and alcohols. The wastewater is discharged to the local Publicly Owned Treatment Works (POTW) under pretreatment regulations which specify an effluent limitation of 5.0 mg/L on the total toxic organic (TTO) concentration which can be placed on the combined BEHP, DNOP, and DNBP ester concentration. Various esters and long chain alcohols present in the wastewater have very low water solubilities and are considered immiscible. They form a dispersed phase in the wastewater that has a specific gravity in the range of 0.88 to 0.93. Separation of the dispersed phase containing the regulated esters from the heavier water phase to consistently below 5.0 mg/L poses a challenge due to the stability of this colloidal suspension. The objective of this study was to evaluate the effectiveness of centrifugation in meeting the 5.0 mg/L effluent limit on the total BEHP, DNOP, and DNBP ester concentration.

  2. Flow Analysis of the Cleveland Clinic Centrifugal Pump

    NASA Technical Reports Server (NTRS)

    Veres, Joseph P.; Golding, Leonard A. R.; Smith, William A.; Horvath, David; Medvedev, Alexander

    1997-01-01

    An implantable ventricular assist rotordynamic blood pump is being developed by the Cleveland Clinic Foundation in cooperation with the NASA Lewis Research Center. At the nominal design condition, the pump provides blood flow at the rate of 5 liters per minute at a pressure rise of 100 mm of mercury and a rotative speed of 3000 RPM. Bench testing of the centrifugal pump in a water/glycerin mixture has provided flow and pressure data at several rotative speeds. A one-dimensional empirical based pump flow analysis computer code developed at NASA Lewis Research Center has been used in the design process to simulate the flow in the primary centrifugal pump stage. The computer model was used to size key impeller and volute geometric parameters that influence pressure rise and flow. Input requirements to the computer model include a simple representation of the pump geometry. The model estimates the flow conditions at the design and at off-design operating conditions at the impeller leading and trailing edges and the volute inlet and exit. The output from the computer model is compared to flow and pressure data obtained from bench testing.

  3. Use minimum flow data to prolong centrifugal pump life

    SciTech Connect

    Reynolds, J.A.

    1996-03-01

    Environmental and safety concerns and, in the US, the consequences of failing of meet EPA regulations are intensifying efforts to improve the reliability of pumping equipment. A critical step toward achieving this goal is eliminating cavitation, and the resulting impeller and shaft vibrations, which, ultimately, cause seal and bearing failure. In centrifugal pumps, cavitation results when they run at very low flow rates, as can happen during unplanned upsets or interruptions. This particularly true since many centrifugal pumps are now controlled by automatic valves in their discharge lines. The problem can be prevented by providing a small bypass line to the pump`s suction source, to control temperature rise in the pump. Usually, the minimum flow is so low that the bypass loop can be kept open without detracting from the pump`s efficiency. It needn`t require a flow control valve or any special instrumentation, but will let the pump run at a comfortable flow, even with the control valve closed. This paper describes a method to determine minimum thermal flow to prevent cavitation.

  4. Numerical Study of Unsteady Flow in Centrifugal Cold Compressor

    NASA Astrophysics Data System (ADS)

    Zhang, Ning; Zhang, Peng; Wu, Jihao; Li, Qing

    In helium refrigeration system, high-speed centrifugal cold compressor is utilized to pumped gaseous helium from saturated liquid helium tank at low temperature and low pressure for producing superfluid helium or sub-cooled helium. Stall and surge are common unsteady flow phenomena in centrifugal cold compressors which severely limit operation range and impact efficiency reliability. In order to obtain the installed range of cold compressor, unsteady flow in the case of low mass flow or high pressure ratio is investigated by the CFD. From the results of the numerical analysis, it can be deduced that the pressure ratio increases with the decrease in reduced mass flow. With the decrease of the reduced mass flow, backflow and vortex are intensified near the shroud of impeller. The unsteady flow will not only increase the flow loss, but also damage the compressor. It provided a numerical foundation of analyzing the effect of unsteady flow field and reducing the flow loss, and it is helpful for the further study and able to instruct the designing.

  5. Design Attributes and Scale Up Testing of Annular Centrifugal Contactors

    SciTech Connect

    David H. Meikrantz; Jack D. Law

    2005-04-01

    Annular centrifugal contactors are being used for rapid yet efficient liquid- liquid processing in numerous industrial and government applications. Commercialization of this technology began eleven years ago and now units with throughputs ranging from 0.25 to 700 liters per minute are readily available. Separation, washing, and extraction processes all benefit from the use of this relatively new commercial tool. Processing advantages of this technology include: low in-process volume per stage, rapid mixing and separation in a single unit, connection-in-series for multi-stage use, and a wide operating range of input flow rates and phase ratios without adjustment. Recent design enhancements have been added to simplify maintenance, improve inspection ability, and provide increased reliability. Cartridge-style bearing and mechanical rotary seal assemblies that can include liquid-leak sensors are employed to enhance remote operations, minimize maintenance downtime, prevent equipment damage, and extend service life. Clean-in-place capability eliminates the need for disassembly, facilitates the use of contactors for feed clarification, and can be automated for continuous operation. In nuclear fuel cycle studies, aqueous based separations are being developed that efficiently partition uranium, actinides, and fission products via liquid-liquid solvent extraction. Thus, annular centrifugal contactors are destined to play a significant role in the design of such new processes. Laboratory scale studies using mini-contactors have demonstrated feasibility for many such separation processes but validation at an engineering scale is needed to support actual process design.

  6. Magnetically suspended centrifugal blood pump with a radial magnetic driver.

    PubMed

    Hoshi, Hideo; Katakoa, Kiroyuki; Ohuchi, Katsuhiro; Asama, Jun-ichi; Shinshi, Tadahiko; Shimokohbe, Akira; Takatani, Setsuo

    2005-01-01

    A new magnetic bearing has been designed to achieve a low electronic power requirement and high stiffness. The magnetic bearing consists of 1) radial passive forces between the permanent magnet ring mounted inside the impeller rotor and the electromagnet core materials in the pump casing and 2) radial active forces generated by the electromagnets using the two gap sensor signals. The magnetic bearing was assembled into a centrifugal rotary blood pump (CRBP) driven with a radial, magnetic coupled driver. The impeller vane shape was designed based upon the computational fluid dynamic simulation. The diameter and height of the CRBP were 75 mm and 50 mm, respectively. The magnetic bearing system required the power of 1.0-1.4 W. The radial impeller movement was controlled to within +/- 10 microm. High stiffness in the noncontrolled axes, Z, phi, and theta, was obtained by the passive magnetic forces. The pump flow of 5 L/min against 100 mm Hg head pressure was obtained at 1,800 rpm with the electrical to hydraulic efficiency being greater than 15%. The Normalized Index of Hemolysis (NIH) of the magnetic bearing CRBP was one fifth of the BioPump BP-80 and one half of the NIKKISO HPM-15 after 4 hours. The newly designed magnetic bearing with two degrees of freedom control in combination with optimized impeller vane was successful in achieving an excellent hemolytic performance in comparison with the clinical centrifugal blood pumps. PMID:15745136

  7. Prediction of leakage flow in a shrouded centrifugal blood pump.

    PubMed

    Teo, Ji-Bin; Chan, Weng-Kong; Wong, Yew-Wah

    2010-09-01

    This article proposes a phenomenological model to predict the leakage flow in the clearance gap of shrouded centrifugal blood pumps. A good washout in the gap clearance between the rotating impeller surfaces and volute casing is essential to avoid thrombosis. However, excessive leakage flow will result in higher fluid shear stress that may lead to hemolysis. Computational fluid dynamics (CFD) analysis was performed to investigate the leakage flow in a miniaturized shrouded centrifugal blood pump operating at a speed of 2000 rpm. Based on an analytical model derived earlier, a phenomenological model is proposed to predict the leakage flow. The leakage flow rate is found to be proportional to h(?) , where h is the gap size and the exponent ? ranges from 2.955 to 3.15 for corresponding gap sizes of 0.2-0.5 mm. In addition, it is observed that ? is a linear function of the gap size h. The exponent ? compensates for the variation of pressure difference along the circumferential direction as well as inertia effects that are dominant for larger gap clearances. The proposed model displays good agreement with computational results. The CFD analysis also showed that for larger gap sizes, the total leakage flow rate is of the same order of magnitude as the operating flow rate, thus suggesting low volumetric efficiency. PMID:20883397

  8. Concrete Cleaning, Inc. centrifugal shot blaster: Baseline report; Greenbook (chapter)

    SciTech Connect

    1997-07-31

    The centrifugal shot blaster technology was tested and is being evaluated at Florida International University (FIU) as a baseline technology. In conjunction with FIU`s evaluation of efficiency and cost, this report covers the evaluation conducted for safety and health issues. It is a commercially available technology and has been used for various projects at locations throughout the country. The centrifugal shot blaster is an electronically operated shot blast machine that has been modified to remove layers of concrete to varying depths. A hardened steel shot propelled at a high rate of speed abrades the surface of the concrete. The depth of material removed is determined by the rate of speed the machine is traveling and the volume of shot being fired into the blast chamber. The steel shot is recycled and used over until it is pulverized into dust, which ends up in the waste container with the concrete being removed. Debris is continually vacuumed by a large dust collection system attached to the shot blaster. The safety and health evaluation during the human factors assessment focused on two main areas: noise and dust.

  9. Concrete Cleaning, Inc. centrifugal shot blaster: Baseline report

    SciTech Connect

    1997-07-31

    The centrifugal shot blaster technology was tested and is being evaluated at Florida International University (FIU) as a baseline technology. In conjunction with FIU`s evaluation of efficiency and cost, this report covers the evaluation conducted for safety and health issues. It is a commercially available technology and has been used for various projects at locations throughout the country. The centrifugal shot blaster is an electronically operated shot blast machine that has been modified to remove layers of concrete to varying depths. A hardened steel shot propelled at a high rate of speed abrades the surface of the concrete. The depth of material removed is determined by the rate of speed the machine is traveling and the volume of shot being fired into the blast chamber. The steel shot is recycled and used over until it is pulverized into dust, which ends up in the waste container with the concrete being removed. Debris is continually vacuumed by a large dust collection system attached to the shot blaster. The safety and health evaluation during the human factors assessment focused on two main areas: noise and dust.

  10. Centrifuge study of DNAPL transport in granular media

    SciTech Connect

    Pantazidou, M.; Abu-Hassanein, Z.S.; Riemer, M.F.

    2000-02-01

    The migration potential of dense nonaqueous phase liquids (DNAPLs) in saturated soil was investigated experimentally using the elevated acceleration field of the geotechnical centrifuge. The transport of the DNAPL was monitored with a video camera in flight, through the transparent wall of the sample box. By using measurements of the velocity of the DNAPL front from models corresponding to the same prototype and applying the technique of modeling of models, the stable infiltration of a low density, high viscosity DNAPL in saturated homogeneous media was shown to scale properly in the centrifuge. The visual observations confirmed the correlations between the DNAPL physicochemical properties and transport patterns, which have important consequences for the characterization of DNAPL-contaminated sites. Infiltrating DNAPLs of high density and low viscosity displace water in an unstable manner and create extensive contaminated areas characterized by non-uniform DNAPL distributions. In contrast, the displacement of water by DNAPLs of low density and high viscosity is stable and efficient, and hence, results in smaller contaminated areas of high DNAPL saturation. Numerical simulations yielded predictions and sensitivity analysis results that agreed well with these experimental observations.

  11. Analysis and optimization of aerodynamic noise in a centrifugal compressor

    NASA Astrophysics Data System (ADS)

    Sun, Hyosung; Shin, Hyungki; Lee, Soogab

    2006-02-01

    The numerical methods for the performance analysis and the noise prediction of the centrifugal compressor impeller are developed, which are coupled with the optimization design methodology consisting of response surface method, statistical approach, and genetic algorithm. Navier-Stokes equations with the two-equation ( k- ?) turbulence model are applied to calculate impeller aerodynamic characteristics, and Ffowcs Williams-Hawkings formulation and boundary element method are used to predict the impeller aerodynamic noise on the basis of impeller flow field results. The computational codes are verified through the comparison of measured data. The quadratic response surface model with D-optimal three-level factorial experimental design points is constructed to optimize the impeller geometry for the advanced centrifugal compressor, and it is shown that the quadratic model exhibits a reasonable fitting quality resulting in the impeller blade design with the high performance and the low far-field noise level. The influences of selected design variables and their mutual interactions as well as the effects of various objective functions and constraints on the impeller performance and the impeller noise are also examined as a result of the optimization process.

  12. Artificial gravity: head movements during short-radius centrifugation

    NASA Technical Reports Server (NTRS)

    Young, L. R.; Hecht, H.; Lyne, L. E.; Sienko, K. H.; Cheung, C. C.; Kavelaars, J.

    2001-01-01

    Short-radius centrifugation is a potential countermeasure to long-term weightlessness. Unfortunately, head movements in a rotating environment induce serious discomfort, non-compensatory vestibulo-ocular reflexes, and subjective illusions of body tilt. In two experiments we investigated the effects of pitch and yaw head movements in participants placed supine on a rotating bed with their head at the center of rotation, feet at the rim. The vast majority of participants experienced motion sickness, inappropriate vertical nystagmus and illusory tilt and roll as predicted by a semicircular canal model. However, a small but significant number of the 28 participants experienced tilt in the predicted plane but in the opposite direction. Heart rate was elevated following one-second duration head turns. Significant adaptation occurred following a series of head turns in the light. Vertical nystagmus, motion sickness and illusory tilt all decreased with adaptation. Consequences for artificial gravity produced by short-radius centrifuges as a countermeasure are discussed. Grant numbers: NCC 9-58. c 2001. Elsevier Science Ltd. All rights reserved.

  13. Analysis of cavitation behaviour in a centrifugal pump

    NASA Astrophysics Data System (ADS)

    He, M.; Fu, L. P.; Zhou, L. J.; Guo, Q.; Wang, Z. W.

    2012-11-01

    Cavitation is a well-known problem in centrifugal pumps, causing serious damage and substantial head losses. However, the reason for the sudden head drop in cavitation curves is not fully understood. In this paper, the transient three-dimensional cavitating flow field in a centrifugal pump was calculated using RNG k-? turbulence model and Rayleigh Plesset cavitation model. The NPSH-H curve and the cavitation development in the whole passage were predicted. The blade loading and energy transfer are analyzed for various cavitation conditions. The results show that the existing of the cavities changes the load distribution on blades. With the decrease of NPSH the loads on blades tend to increases in the rear part but decreases in the front part. If NPSH is not so low, sometimes the overall torque may increase slightly, thus the head may also increase slightly. But if the NPSH become low and reach a threshold value, the overall torque will also decrease. At the same time, the energy dissipation in the vortices increases greatly because of the growth of the cavities. These two reasons make the head drop rapidly.

  14. Experiments on Plasma Injection into a Centrifugally Confined System

    NASA Astrophysics Data System (ADS)

    Messer, S.; Bomgardner, R.; Brockington, S.; Case, A.; Witherspoon, F. D.; Uzun-Kaymak, I.; Elton, R.; Young, W.; Teodorescu, C.; Morales, C. H.; Ellis, R. F.

    2009-11-01

    We describe the cross-field injection of plasma into a centrifugally-confined system. Two different types of plasma railgun have been installed on the Maryland Centrifugal Experiment (MCX) in an attempt to drive that plasma's rotation. The initial gun was a coaxial device designed to mitigate the blowby instability. The second one was a MiniRailgun with a rectangular bore oriented so that the MCX magnetic field augments the railgun's internal magnetic field. Tests at HyperV indicate this MiniRailgun reaches much higher densities than the original gun, although muzzle velocity is slightly reduced. We discuss the impact of these guns on MCX for various conditions. Initial results show that even for a 2 kG field, firing the MiniRailgun modifies oscillations of the MCX diamagnetic loops and can impact the core current and voltage. The gun also has a noticeable impact on MCX microwave emissions. These observations suggest plasma enters the MCX system. We also compare diagnostic data collected separately from MCX for these and other guns, focussing primarily on magnetic measurements.

  15. The performance of a centrifugal compressor with high inlet prewhirl

    SciTech Connect

    Whitfield, A.; Abdullah, A.H.

    1998-07-01

    The performance requirements of centrifugal compressors usually include a broad operating range between surge and choke. This becomes increasingly difficult to achieve as increased pressure ratio is demanded. In order to suppress the tendency to surge and extend the operating range at low flow rates, inlet swirl is often considered through the application of inlet guide vanes. To generate high inlet swirl angles efficiently, an inlet volute has been applied as the swirl generator, and a variable geometry design developed in order to provide zero swirl. The variable geometry approach can be applied to increase the swirl progressively or to switch rapidly from zero swirl to maximum swirl. The variable geometry volute and the swirl conditions generated are described. The performance of a small centrifugal compressor is presented for a wide range of inlet swirl angles. In addition to the basic performance characteristics of the compressor, the onsets of flow reversals at impeller inlet are presented, together with the development of pressure pulsations, in the inlet and discharge ducts, through to full surge. The flow rate at which surge occurred was shown, by the shift of the peak pressure condition and by the measurement of the pressure pulsations, to be reduced by over 40%.

  16. Cardio-postural interactions and short-arm centrifugation.

    NASA Astrophysics Data System (ADS)

    Blaber, Andrew; Goswami, Nandu; Xu, Da; Laurin, Alexendre

    INTRODUCTION: We are interested in mechanisms associated with orthostatic tolerance. In previous studies we have shown that postural muscles in the calf contribute to both posture and blood pressure regulation during orthostatic stress. In this study we investigated the relationship between cardiovascular and postural muscle control before, during and after short arm human centrifuge (SAHC) up to 2.2 G. METHODS: Eleven healthy young subjects (6 m, 5 f), with no history of cardiovascular disease, falls or orthostatic hypotension, participated. All were familiarized with the SAHC with 10 minutes at 1-G at the feet. Each subject was instrumented in the supine position on the SAHC for beat-to-beat ECG and blood pressure (Portapres derived SBP). Bilateral lower leg EMG was collected from four leg postural muscles: tibialis anterior, medial gastrocnemius, lateral gastrocnemius, and medial soleus. Transdermal differential recording of signals was performed using an 8-channel EMG system, (Myosystem 1200, Noraxon Inc., Arizona, USA). Postural sway data of the body COP was computed from the force and moment data collected with a force platform (Accusway, AMTI, MA, USA). Before and after SAHC, the subject stood on a force platform with their gaze fixed on a point at eye level, closed their eyes and stood quietly for 5 min. A final stand was conducted 30 min after centrifugation with supine rest in between. During clockwise centrifugation (10-min 1g and 10-min 2.2g at the foot) the subjects’ head was hooded and in the dark. The subject’s body was restrained into the rotation arm with a parachute harness and given additional body support with a foot-plate. ECG, EMG and BP data were collected throughout and centre of pressure trajectory (COP) collected during the stand test. Subjects were requested to relax and not to voluntarily contract the leg muscles; however, they were not to suppress contractions as they occurred involuntarily or by reflex. A Continuous Wavelet Transform was applied to decompose the representative signals on a time-scale basis in a frequency region of [0.01 - 0.1] Hz. Their linear coupling was quantified through a coherence metric and the synchrony was characterised via the phase information to determine regions where pairs of signals were in phase lock and thereby inferring an interaction or coupling. From these data we investigate the percent time in each of two coupled interactions: EMG-SBP and COP-SBP. RESULTS: The time percentages from EMG-SBP was 6.2% (baseline), 8.1% (pre-stand), 7.7% (1g), 13.6% (2g), 10.8% (post-stand), and 8.2 (recovery-stand).ANOVA comparison (EMG-SBP) among baseline supine (6.2%), 1g (7.7%), and 2g (13.6%) yielded a p value of 0.04. Student-Newman-Keuls post hoc test showed that 2g is significantly higher than supine1 (p=0.04) and marginal significant difference between 1g and 2g (p=0.052). There was no effect of centrifugation on stand EMG-SBP, but COP-SBP was marginally increased in the recovery stand (pre-stand: 10.5%; post-stand 8.9%; recovery-stand 15.7%, p=0.20). CONCLUSION: These data indicated the activation of cardio-postural control system throughout stand and supine centrifugation, with elevation of the recruitment of muscle pump at 2g.

  17. Compaction of Chromite Cumulates applying a Centrifuging Piston-Cylinder

    NASA Astrophysics Data System (ADS)

    Manoochehri, S.; Schmidt, M. W.

    2012-12-01

    Stratiform accumulations of chromite cumulates, such as the UG2 chromitite layer in the Bushveld Complex, is a common feature in most of the large layered mafic intrusions. The time scales and mechanics of gravitationally driven crystal settling and compaction and the feasibility of these processes for the formation of such cumulate layers is investigated through a series of high temperature (1280-1300 °C) centrifuge-assisted experiments at 100-2000 g, 0.4-0.6 GPa. A mixture of natural chromite, with defined grain sizes (means of 5 ?m, 13 ?m, and 52 ?m), and a melt with a composition thought to represent the parental magma of the Bushveld Complex, was first chemically and texturally equilibrated at static conditions and then centrifuged. Centrifugation leads to a single cumulate layer formed at the gravitational bottom of the capsule. This layer was analysed for porosity, mean grain size, size distribution and also travelling distance of chromite crystals. The experimentally observed mechanical settling velocity of chromite grains in a suspension with ~ 24 vol% crystals is calculated to be about half (~ 0.53) of the Stokes settling velocity, consistent with a sedimentation exponent n of 2.35±0.3. The settling leads to a porosity of about 52 % in the chromite layer. Formation times of chromite orthocumulates with initial crystal content in the melt of 1 % and grain sizes of 2 mm are thus around 0.6 m/day. To achieve more compacted chromite piles, centrifugation times and acceleration were increased. Within each experiment the crystal content of the cumulate layer increases downward almost linearly at least in the lower 2/3 of the cumulate pile. Although porosity in the lowermost segment of the chromite layer decreases with increasing effective stress integrated over time, the absolute decrease is smaller than for experiments with olivine (from a previous study). Formation times of a ½ meter single chromite layer with 70 vol% chromite, is calculated to be around 20 years whereas this value is around 0.4 years for olivine cumulates. When considering a natural outcrop of a layered intrusion with multiple layers of about 50 meters height, adcumulate formation time decreases to a few months. With increasing the effective stress integrated over time, applied during centrifugation, crystal size distribution histograms move slightly toward larger grain sizes, but looking at mean grain sizes, a narrow range of changes can be observed. Classic crystal size distribution profiles corrected for real 3D sizes (CSDCorrectin program) of the chromite grains in different experiments illustrate a collection of parallel log-linear trends at larger grain sizes with a very slight overturn at small grain sizes. This is in close agreement with the idealized CSD plots of adcumulus growth.

  18. Effects of Space Flight, Clinorotation, and Centrifugation on the Growth and Metabolism of Escherichia Coli

    NASA Technical Reports Server (NTRS)

    Brown, Robert B.

    1999-01-01

    Previous experiments have shown that space flight stimulates bacterial growth and metabolism. An explanation for these results is proposed, which may eventually lead to improved terrestrial pharmaceutical production efficiency. It is hypothesized that inertial acceleration affects bacterial growth and metabolism by altering the transport phenomena in the cells external fluid environment. It is believed that this occurs indirectly through changes in the sedimentation rate acting on the bacteria and buoyancy-driven convection acting on their excreted by-products. Experiments over a broad range of accelerations consistently supported this theory. Experiments at I g indicated that higher concentrations of excreted by products surrounding bacterial cells result in a shorter lag phase. Nineteen additional experiments simulated 0 g and 0.5 g using a clinostat, and achieved 50 g, 180 g, and 400 g using a centrifuge. These experiments showed that final cell density is inversely related to the level of acceleration. The experiments also consistently showed that acceleration affects the length of the lag phase in a non-monotonic, yet predictable, manner. Additional data indicated that E. coli metabolize glucose less efficiently at hypergravity, and more efficiently at hypogravity. A space-flight experiment was also performed. Samples on orbit had a statistically significant higher final cell density and more efficient metabolism than did ground controls. These results. which were similar to simulations of 0 g using a clinostat, support the theory that gravity only affects bacterial growth and metabolism indirectly, through changes in the bacteria's fluid environment.

  19. Centrifugal accelerator, system and method for removing unwanted layers from a surface

    DOEpatents

    Foster, Christopher A. (Clinton, TN); Fisher, Paul W. (Heiskell, TN)

    1995-01-01

    A cryoblasting process having a centrifugal accelerator for accelerating frozen pellets of argon or carbon dioxide toward a target area utilizes an accelerator throw wheel designed to induce, during operation, the creation of a low-friction gas bearing within internal passages of the wheel which would otherwise retard acceleration of the pellets as they move through the passages. An associated system and method for removing paint from a surface with cryoblasting techniques involves the treating, such as a preheating, of the painted surface to soften the paint prior to the impacting of frozen pellets thereagainst to increase the rate of paint removal. A system and method for producing large quantities of frozen pellets from a liquid material, such as liquid argon or carbon dioxide, for use in a cryoblasting process utilizes a chamber into which the liquid material is introduced in the form of a jet which disintegrates into droplets. A non-condensible gas, such as inert helium or air, is injected into the chamber at a controlled rate so that the droplets freeze into bodies of relatively high density.

  20. Quantum Kinetic Theory I: A Quantum Kinetic Master Equation for Condensation of a weakly interacting Bose gas without a trapping potential

    E-print Network

    C. W. Gardiner; P. Zoller

    1996-11-25

    A Quantum Kinetic Master Equation (QKME) for bosonic atoms is formulated. It is a quantum stochastic equation for the kinetics of a dilute quantum Bose gas, and describes the behavior and formation of Bose condensation. The key assumption in deriving the QKME is a Markov approximation for the atomic collision terms. In the present paper the basic structure of the theory is developed, and approximations are stated and justified to delineate the region of validity of the theory. Limiting cases of the QKME include the Quantum Boltzmann master equation and the Uehling-Uhlenbeck equation, as well as an equation analogous to the Gross-Pitaevskii equation.