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Sample records for high performance centrifugal

  1. 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%.

  2. Calculating High Speed Centrifugal Compressor Performance from Averaged Measurements

    NASA Astrophysics Data System (ADS)

    Lou, Fangyuan; Fleming, Ryan; Key, Nicole L.

    2012-12-01

    To improve the understanding of high performance centrifugal compressors found in modern aircraft engines, the aerodynamics through these machines must be experimentally studied. To accurately capture the complex flow phenomena through these devices, research facilities that can accurately simulate these flows are necessary. One such facility has been recently developed, and it is used in this paper to explore the effects of averaging total pressure and total temperature measurements to calculate compressor performance. Different averaging techniques (including area averaging, mass averaging, and work averaging) have been applied to the data. Results show that there is a negligible difference in both the calculated total pressure ratio and efficiency for the different techniques employed. However, the uncertainty in the performance parameters calculated with the different averaging techniques is significantly different, with area averaging providing the least uncertainty.

  3. Development and Validation of High Performance Unshrouded Centrifugal Impeller

    NASA Technical Reports Server (NTRS)

    Chen, Wei-Chung; Williams, M.; Paris, John K.; Prueger, G. H.; Williams, Robert; Turner, James E. (Technical Monitor)

    2001-01-01

    The feasibility of using a two-stage unshrouded impeller turbopump to replace the current three-stage reusable launch vehicle engine shrouded impeller hydrogen pump has been evaluated from the standpoint of turbopump weight reduction and overall payload improvement. These advantages are a by-product of the higher tip speeds that an unshrouded impeller can sustain. The issues associated with the effect of unshrouded impeller tip clearance on pump efficiency and head have been evaluated with one-dimensional tools and full three-dimensional rotordynamic fluid reaction forces and coefficients have been established through time dependent computational fluid dynamics (CFD) simulation of the whole 360 degree impeller with different rotor eccentricities and whirling ratios. Unlike the shrouded impeller, the unshrouded impeller forces are evaluated as the sum of the pressure forces on the blade and the pressure forces on the hub using the CFD results. The turbopump axial thrust control has been optimized by adjusting the first stage impeller backend wear ring seal diameter and diverting the second stage backend balance piston flow to the proper location. The structural integrity associated with the high tip speed has been checked by analyzing a 3D-Finite Element Model at maximum design conditions (6% higher than the design speed). This impeller was fabricated and tested in the NASA Marshall Space Flight Center water-test rig. The experimental data will be compared with the analytical predictions and presented in another paper. The experimental data provides validation data for the numerical design and analysis methodology. The validated numerical methodology can be used to help design different unshrouded impeller configurations.

  4. SEAL FOR HIGH SPEED CENTRIFUGE

    DOEpatents

    Skarstrom, C.W.

    1957-12-17

    A seal is described for a high speed centrifuge wherein the centrifugal force of rotation acts on the gasket to form a tight seal. The cylindrical rotating bowl of the centrifuge contains a closure member resting on a shoulder in the bowl wall having a lower surface containing bands of gasket material, parallel and adjacent to the cylinder wall. As the centrifuge speed increases, centrifugal force acts on the bands of gasket material forcing them in to a sealing contact against the cylinder wall. This arrangememt forms a simple and effective seal for high speed centrifuges, replacing more costly methods such as welding a closure in place.

  5. Coordinates for a High Performance 4:1 Pressure Ratio Centrifugal Compressor

    NASA Technical Reports Server (NTRS)

    McKain, Ted F.; Holbrook, Greg J.

    1997-01-01

    The objective of this program was to define the aerodynamic design and manufacturing coordinates for an advanced 4:1 pressure ratio, single stage centrifugal compressor at a 10 lbm/sec flow size. The approach taken was to perform an exact scale of an existing DDA compressor originally designed at a flow size of 3.655 lbm/sec.

  6. Preparative separation of major xanthones from mangosteen pericarp using high-performance centrifugal partition chromatography.

    PubMed

    Shan, Yichu; Zhang, Wei

    2010-05-01

    Mangosteen fruit pericarp (MFP) is a rich source of xanthones, which has shown remarkable pharmacological activities. To isolate xanthones, previous methods included labor intensive and time-consuming solid-phase extractions (Sephadex LH20, silica gel) and sequential solvent extraction. In this study, major xanthones (alpha- and gamma-mangostins) in MFP were isolated at high purity in one step utilizing high-performance centrifugal partition chromatography with solvent system composed of petroleum ether, ethyl acetate, methanol and water (10:5:5:1). In one run, 200 mg crude extract of MFP was injected and 55.4 mg alpha-mangostin and 12.4 mg gamma-mangostin were obtained with the purity of 93.6 and 98.4%, respectively. The yields of them were 86.3 and 76.3%, respectively. As alpha- and gamma-mangostins are reported to show potent antioxidant, anti-inflammatory and anticancer activities, this method can be used for the large-scale production of them for future in vitro and in vivo biological studies. PMID:20235130

  7. Aerodynamic Performance of a Compact, High Work-Factor Centrifugal Compressor at the Stage and Subcomponent Level

    NASA Technical Reports Server (NTRS)

    Braunscheidel, Edward P.; Welch, Gerard E.; Skoch, Gary J.; Medic, Gorazd; Sharma, Om P.

    2015-01-01

    The measured aerodynamic performance of a compact, high work-factor, single-stage centrifugal compressor, comprising an impeller, diffuser, 90deg-bend, and exit guide vane is reported. Performance levels are based on steady-state total-pressure and total-temperature rake and angularity-probe data acquired at key machine rating planes during recent testing at NASA Glenn Research Center. Aerodynamic performance at the stage level is reported for operation between 70 to 105 percent of design corrected speed, with subcomponent (impeller, diffuser, and exit-guide-vane) flow field measurements presented and discussed at the 100 percent design-speed condition. Individual component losses from measurements are compared with pre-test CFD predictions on a limited basis.

  8. Aerodynamic Performance of a Compact, High Work-Factor Centrifugal Compressor at the Stage and Subcomponent Level

    NASA Technical Reports Server (NTRS)

    Braunscheidel, Edward P.; Welch, Gerard E.; Skoch, Gary J.; Medic, Gorazd; Sharma, Om P.

    2014-01-01

    The measured aerodynamic performance of a compact, high work-factor, single-stage centrifugal compressor, comprising an impeller, diffuser, 90º-bend, and exit guide vane is reported. Performance levels are based on steady-state total-pressure and total-temperature rake and angularity-probe data acquired at key machine rating planes during recent testing at NASA Glenn Research Center. Aerodynamic performance at the stage level is reported for operation between 70 to 105% of design corrected speed, with subcomponent (impeller, diffuser, and exit-guide-vane) flow field measurements presented and discussed at the 100% design-speed condition. Individual component losses from measurements are compared with pre-test CFD predictions on a limited basis.

  9. Aerodynamic Performance of a Compact, High Work-Factor Centrifugal Compressor at the Stage and Subcomponent Level

    NASA Technical Reports Server (NTRS)

    Braunscheidel, Edward P.; Welch, Gerard E.; Skoch, Gary J.; Medic, Gorazd; Sharma, Om P.

    2014-01-01

    The measured aerodynamic performance of a compact, high work factor, single-stage centrifugal compressor, comprising an impeller, diffuser, 90-bend, and exit guide vane (EGV), is reported. Performance levels are based on steady-state total-pressure and total-temperature rake and angularity-probe data acquired at key machine rating planes during recent testing at NASA Glenn Research Center. Aerodynamic performance at the stage level are reported for operation between 70 to 105 of design corrected speed, with subcomponent (impeller, diffuser, and exitguide-vane) detailed flow field measurements presented and discussed at the 100 design-speed condition. Individual component losses from measurements are compared with pre-test predictions on a limited basis.

  10. 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.

  11. 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.

  12. Proof of concept and performance optimization of high gravity batch-type centrifugal dryer for dewatering fine coal

    SciTech Connect

    Smith, L.B.; Durney, T.

    1991-01-01

    The primary objective of the project was to assemble, analyze and make use of those data that could help to clearly identify, optimize and confirm the technical and economic advantages that the new high gravity centrifugal dryer technology can provide to the coal industry and to end users. Other objectives were: to confirm the feasibility of the dryer for drying coals from a number of different seams; to use the data base for optimizing the dryer's systems, and: to produce projected technical and economic comparisons with thermal dryers as applied to an existing coal processing plant flow sheet. (JL)

  13. 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.

  14. 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

  15. 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.

  16. Effect of high negative incidence on the performance of a centrifugal compressor stage with conventional vaned diffusers

    NASA Astrophysics Data System (ADS)

    Jaatinen, Ahti; Grönman, Aki; Turunen-Saaresti, Teemu; Backman, Jari

    2011-06-01

    Three vaned diffusers, designed to have high negative incidence (-8°) at the design operating point, are studied experimentally. The overall performance (efficiency and pressure ratio) are measured at three rotational speeds, and flow angles before and after the diffuser are measured at the design rotational speed and with three mass flow rates. The results are compared to corresponding results of the original vaneless diffuser design. Attention is paid to the performance at lower mass flows than the design mass flow. The results show that it is possible to improve the performance at mass flows lower than the design mass flow with a vaned diffuser designed with high negative incidence. However, with the vaned diffusers, the compressor still stalls at higher mass flow rates than with the vaneless one. The flow angle distributions after the diffuser are more uniform with the vaned diffusers.

  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

    DOEpatents

    Rushing, F.C.

    1960-09-01

    A vibration damping mechanism for damping vibration forces occurring during the operation of a centrifuge is described. The vibration damping mechanism comprises a plurality of nested spaced cylindrical elements surrounding the rotating shaft of the centrifuge. Some of the elements are held substantially stationary while the others are held with respect to a pair of hearings spaced along the rotating shaft. A fluid is retained about the cylindrical elements.

  19. 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.

  20. Mean streamline aerodynamic performance analysis of centrifugal compressors

    SciTech Connect

    Aungier, R.H.

    1995-07-01

    Aerodynamic performance prediction models for centrifugal compressor impellers are presented. In combination with similar procedures for stationary components, previously published in the open literature, a comprehensive mean streamline performance analysis for centrifugal compressor stages is provided. The accuracy and versatility of the overall analysis is demonstrated for several centrifugal compressor stages of various types, including comparison with intrastage component performance data. Detailed validation of the analysis against experimental data has been accomplished for over a hundred stages, including stage flow coefficients from 0.009 to 0.15 and pressure ratios up to about 3.5. Its application to turbocharger stages includes pressure ratios up to 4.2, but with test uncertainty much greater than for the data used in the detailed validation studies.

  1. Proof of concept and performance optimization of high gravity batch-type centrifugal dryer for dewatering fine coal. Final report, September 20, 1989--September 21, 1991

    SciTech Connect

    Smith, L.B.; Durney, T.

    1991-12-31

    The primary objective of the project was to assemble, analyze and make use of those data that could help to clearly identify, optimize and confirm the technical and economic advantages that the new high gravity centrifugal dryer technology can provide to the coal industry and to end users. Other objectives were: to confirm the feasibility of the dryer for drying coals from a number of different seams; to use the data base for optimizing the dryer`s systems, and: to produce projected technical and economic comparisons with thermal dryers as applied to an existing coal processing plant flow sheet. (JL)

  2. 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.

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

    SciTech Connect

    Rodgers, C.

    1997-07-01

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

  4. Hydrodynamic performance and heat generation by centrifugal pumps.

    PubMed

    Ganushchak, Y; van Marken Lichtenbelt, W; van der Nagel, T; de Jong, D S

    2006-11-01

    For over a century, centrifugal pumps (CP) have been used in various applications, from large industrial pumps to flow pumps for aquariums. However, the use of CP as blood pumps has a rather short history. Consequently, the hydraulic performance data for a blood CP are limited. The aim of our investigation was to study the hydraulic performance and the heat generation of three commercially available CP: Bio-Medicus Bio-Pump BP80 (Medtronic), Rotaflow (Jostra Medizintechnik), and DeltaStream DP2 (MEDOS Medizintechnik AQ). The study was performed using a circuit primed with a water-glycerin mixture with a dynamic viscosity of 0.00272 pa/s. Pressure-flow curves were obtained by a stepwise stagnation of the pump outlet or inlet. The temperature changes were observed using ThermaCAM SC2000 (Flir Systems). The pumps' performance in close to clinical conditions ('operating region') was analysed in this report. The 'operating region' in the case of the BP80 is positioned around the pressure-flow curve at a pump speed of 3000 rpm. In the case of the Rotaflow, the 'operating region' was between the pump pressure-flow curves at a speed of 3000 and 4000 rpm, and the DP2 was found between 7000 and 8000 rpm. The standard deviation of mean pressure through the pump was used to characterise the stability of the pump. In experiments with outlet stagnation, the BP80 demonstrated high negative association between flow and pressure variability (r = -0.68, p < 0.001). In experiments with the DP2, this association was positive (r = 0.68, p < 0.001). All pumps demonstrated significantly higher variability of pressure in experiments with inlet stagnation in comparison to the experiments with outlet stagnation. The rise of relative temperature in the inlet of a pump was closely related to the flow rate. The heating of fluid was more pronounced in the 'zero-flow' mode, especially in experiments with inlet stagnation. In summary, (1) the 'zero-flow' regime, which is described in the manuals

  5. 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 κ-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.

  6. Axial and centrifugal pump meanline performance analysis

    NASA Technical Reports Server (NTRS)

    Veres, Joseph P.

    1994-01-01

    A meanline pump flow modeling method has been developed to provide a fast capability for modeling pumps of cryogenic rocket engines. Based on this method, a meanline pump flow code (PUMPA) has been written that can predict the performance of pumps at off-design operating conditions, given the loss of the diffusion system at the design point. The design point rotor efficiency is obtained from empirically derived correlations of loss to rotor specific speed. The rapid input setup and computer run time for the meanline pump flow code makes it an effective analysis and conceptual design tool. The map generation capabilities of the PUMPA code provide the information needed for interfacing with a rocket engine system modeling code.

  7. Simulation of centrifugal compressor transient performance for process plant applications

    SciTech Connect

    MacDougal, I.; Elder, R.L.

    1983-01-01

    The development of a theoretical model capable of simulating centrifugal compressor transient performance (including compressor surge) is detailed. Simulation results from a Fortran computer program are compared with measured compressor transient data. Good simulation of compressor transients between stable operating points, and compressor presurge flow oscillations has been obtained. General application criteria are presented for the geometric distribution of model elements within a compressor system. Model applications and future work are outlined.

  8. Numerical study of a high-speed miniature centrifugal compressor

    NASA Astrophysics Data System (ADS)

    Li, Xiaoyi

    A miniature centrifugal compressor is a key component of reverse Brayton cycle cryogenic cooling system. The system is commonly used to generate a low cryogenic temperature environment for electronics to increase their efficiency, or generate, store and transport cryogenic liquids, such as liquid hydrogen and oxygen, where space limit is also an issue. Because of space limitation, the compressor is composed of a radial IGV, a radial impeller and an axial-direction diffuser (which reduces the radial size because of smaller diameter). As a result of reduction in size, rotating speed of the impeller is as high as 313,000 rpm, and Helium is used as the working fluid, in order to obtain the required static pressure ratio/rise. Two main characteristics of the compressor---miniature and high-speed, make it distinct from conventional compressors. Higher compressor efficiency is required to obtain a higher COP (coefficient of performance) system. Even though miniature centrifugal compressors start to draw researchers' attention in recent years, understanding of the performance and loss mechanism is still lacking. Since current experimental techniques are not advanced enough to capture details of flow at miniature scale, numerical methods dominate miniature turbomachinery study. This work numerically studied a high speed miniature centrifugal compressor with commercial CFD code. The overall performance of the compressor was predicted with consideration of interaction between blade rows by using sliding mesh model. The law of similarity of turbomachinery was validated for small scale machines. It was found that the specific ratio effect needs to be considered when similarity law is applied. But Reynolds number effect can be neglected. The loss mechanism of each component was analyzed. Loss due to turning bend was significant in each component. Tip leakage loss of small scale turbomachines has more impact on the impeller performance than that of large scale ones. Because the

  9. 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

  10. Performance characteristics of the Cooper PC-9 centrifugal compressor

    SciTech Connect

    Foster, R.E.; Neely, R.F.

    1988-06-30

    Mathematical performance modeling of the PC-9 centrifugal compressor has been completed. Performance characteristics curves have never been obtained for them in test loops with the same degree of accuracy as for the uprated axial compressors and, consequently, computer modeling of the top cascade and purge cascades has been very difficult and of limited value. This compressor modeling work has been carried out in an attempt to generate data which would more accurately define the compressor's performance and would permit more accurate cascade modeling. A computer code, COMPAL, was used to mathematically model the PC-9 performance with variations in gas composition, flow ratios, pressure ratios, speed and temperature. The results of this effort, in the form of graphs, with information about the compressor and the code, are the subject of this report. Compressor characteristic curves are featured. 13 figs.

  11. Effects of Impeller-Diffuser Interaction on Centrifugal Compressor Performance

    NASA Technical Reports Server (NTRS)

    Tan, Choon S.

    2003-01-01

    This research program focuses on characterizing the effect of impeller-diffuser interactions in a centrifugal compressor stage on its performance using unsteady threedimensional Reynolds-averaged Navier-Stokes simulations. The computed results show that the interaction between the downstream diffuser pressure field and the impeller tip clearance flow can account for performance changes in the impeller. The magnitude of performance change due to this interaction was examined for an impeller with varying tip clearance followed by a vaned or vaneless diffuser. The impact of unsteady impeller-diffuser interaction, primarily through the impeller tip clearance flow, is reflected through a time-averaged change in impeller loss, blockage and slip. The results show that there exists a tip clearance where the beneficial effect of the impeller-diffuser interaction on the impeller performance is at a maximum. A flow feature that consists of tip flow back leakage was shown to occur at design speed for the centrifugal compressor stage. This flow phenomenon is described as tip flow that originates in one passage, flows downstream of the impeller trailing edge and then returns to upstream of the impeller trailing edge of a neighboring passage. Such a flow feature is a source of loss in the impeller. A hypothesis is put forth to show that changing the diffuser vane count and changing impeller-diffuser gap has an analogous effect on the impeller performance. The centrifugal compressor stage was analyzed using diffusers of different vane counts, producing an impeller performance trend similar to that when the impeller-diffuser gap was varied, thus supporting the hypothesis made. This has the implication that the effect impeller performance associated with changing the impeller-diffuser gap and changing diffuser vane count can be described by the non-dimensional ratio of impeller-diffuser gap to diffuser vane pitch. A procedure is proposed and developed for isolating impeller passage

  12. CENTRIFUGE APPARATUS

    DOEpatents

    Skarstrom, C.; Urey, H.C.; Cohen, K.

    1960-08-01

    A high-speed centrifuge for the separation of gaseous isotopes is designed comprising a centrifugal pump mounted on the outlet of a centrifuge bowl and arranged to pump the heavy and light fractions out of the centrifuge bowl in two separate streams.

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

    SciTech Connect

    Gui, F.; Reinarts, T.R.; Scaringe, R.P.; Gottschlich, J.M.

    1995-12-31

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

  14. Cavitation Performance of a Centrifugal Pump with Water and Mercury

    NASA Technical Reports Server (NTRS)

    Hammitt, F. G.; Barton, R. K.; Cramer, V. F.; Robinson, M. J.

    1961-01-01

    The cavitation performance of a given centrifugal pump with water (hot and cold) and mercury is compared. It is found that there are significant scale effects with all fluids tested, with the Thoma cavitation parameter decreasing in all cases for increased pump speed or fluid Reynolds' number. The data for a fixed flow coefficient fall into a single curve when plotted against pump speed (or fluid velocity), rather than against Reynolds' number. Conversely, the Thoma parameter for a given Reynolds' number is approximately twice as large for mercury as for water. The direction of this variation is as predicted from consideration of the cavitation thermodynamic parameters which vary by a factor of 10(exp 7) between these fluids. No difference in cavitation performance between hot and cold water (approximately 160 F and 80 F) was observed, However, the thermodynamic parameters vary only by a factor of 5.

  15. 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.

  16. 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.

  17. Excessive centrifugal fields damage high density lipoprotein[S

    PubMed Central

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

    2015-01-01

    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

  18. A wireless high-speed data acquisition system for geotechnical centrifuge model testing

    NASA Astrophysics Data System (ADS)

    Gaudin, C.; White, D. J.; Boylan, N.; Breen, J.; Brown, T.; DeCatania, S.; Hortin, P.

    2009-09-01

    This paper describes a novel high-speed wireless data acquisition system (WDAS) developed at the University of Western Australia for operation onboard a geotechnical centrifuge, in an enhanced gravitational field of up to 300 times Earth's gravity. The WDAS system consists of up to eight separate miniature units distributed around the circumference of a 0.8 m diameter drum centrifuge, communicating with the control room via wireless Ethernet. Each unit is capable of powering and monitoring eight instrument channels at a sampling rate of up to 1 MHz at 16-bit resolution. The data are stored within the logging unit in solid-state memory, but may also be streamed in real-time at low frequency (up to 10 Hz) to the centrifuge control room, via wireless transmission. The high-speed logging runs continuously within a circular memory (buffer), allowing for storage of a pre-trigger segment of data prior to an event. To suit typical geotechnical modelling applications, the system can record low-speed data continuously, until a burst of high-speed acquisition is triggered when an experimental event occurs, after which the system reverts back to low-speed acquisition to monitor the aftermath of the event. Unlike PC-based data acquisition solutions, this system performs the full sequence of amplification, conditioning, digitization and storage on a single circuit board via an independent micro-controller allocated to each pair of instrumented channels. This arrangement is efficient, compact and physically robust to suit the centrifuge environment. This paper details the design specification of the WDAS along with the software interface developed to control the units. Results from a centrifuge test of a submarine landslide are used to illustrate the performance of the new WDAS.

  19. Multi-objective optimization design and experimental investigation of centrifugal fan performance

    NASA Astrophysics Data System (ADS)

    Zhang, Lei; Wang, Songling; Hu, Chenxing; Zhang, Qian

    2013-11-01

    Current studies of fan performance optimization mainly focus on two aspects: one is to improve the blade profile, and another is only to consider the influence of single impeller structural parameter on fan performance. However, there are few studies on the comprehensive effect of the key parameters such as blade number, exit stagger angle of blade and the impeller outlet width on the fan performance. The G4-73 backward centrifugal fan widely used in power plants is selected as the research object. Based on orthogonal design and BP neural network, a model for predicting the centrifugal fan performance parameters is established, and the maximum relative errors of the total pressure and efficiency are 0.974% and 0.333%, respectively. Multi-objective optimization of total pressure and efficiency of the fan is conducted with genetic algorithm, and the optimum combination of impeller structural parameters is proposed. The optimized parameters of blade number, exit stagger angle of blade and the impeller outlet width are seperately 14, 43.9°, and 21 cm. The experiments on centrifugal fan performance and noise are conducted before and after the installation of the new impeller. The experimental results show that with the new impeller, the total pressure of fan increases significantly in total range of the flow rate, and the fan efficiency is improved when the relative flow is above 75%, also the high efficiency area is broadened. Additionally, in 65% -100% relative flow, the fan noise is reduced. Under the design operating condition, total pressure and efficiency of the fan are improved by 6.91% and 0.5%, respectively. This research sheds light on the considering of comprehensive effect of impeller structrual parameters on fan performance, and a new impeller can be designed to satisfy the engineering demand such as energy-saving, noise reduction or solving air pressure insufficiency for power plants.

  20. Modified fabrication techniques lead to improved centrifugal blood pump performance.

    PubMed

    Pacella, J J; Goldstein, A H; Magovern, G J; Clark, R F

    1994-01-01

    The authors are developing an implantable centrifugal blood pump for short- and medium-term (1-6 months) left ventricular assist. They hypothesized that the application of result dependent modifications to this pump would lead to overall improved performance in long-term implantation studies. Essential requirements for pump operation, such as durability and resistance to clot formation, have been achieved through specialized fabrication techniques. The antithrombogenic character of the pump has been improved through coating at the cannula-housing interfaces and the baffle seal, and through changing the impeller blade material from polysulfone to pyrolytic carbon. The electronic components of the pump have been sealed for implantable use through specialized processes of dipping and potting, and the surfaces of the internal pump components have been treated to increase durability. The device has demonstrated efficacy in five chronic sheep implantation studies of 14, 10, 28, 35, and 154 day duration. Post mortem findings from the 14 day experiment showed stable fibrin entangled around the impeller shaft and blades. After pump modification, autopsy findings of the 10 day study showed no evidence of clot. Additionally, the results of the 28 day experiment showed only a small (2.0 mm) ring of fibrin at the shaft-seal interface. In the 35 and 154 day experiments, redesign of the stators have resulted in improved motor corrosion resistance. The 35 day study showed a small, 0.5 mm wide fibrin deposit at the lip seal, but no motor failure. In the 154 day experiment, the motor failed because of stator fluid corrosion, while the explanted pump was devoid of thrombus. Based on these findings, the authors believe that these pump refinements have contributed significantly to improvements in durability and resistance to clot formation. PMID:8555619

  1. Centrifugal fans: Similarity, scaling laws, and fan performance

    NASA Astrophysics Data System (ADS)

    Sardar, Asad Mohammad

    Centrifugal fans are rotodynamic machines used for moving air continuously against moderate pressures through ventilation and air conditioning systems. There are five major topics presented in this thesis: (1) analysis of the fan scaling laws and consequences of dynamic similarity on modelling; (2) detailed flow visualization studies (in water) covering the flow path starting at the fan blade exit to the evaporator core of an actual HVAC fan scroll-diffuser module; (3) mean velocity and turbulence intensity measurements (flow field studies) at the inlet and outlet of large scale blower; (4) fan installation effects on overall fan performance and evaluation of fan testing methods; (5) two point coherence and spectral measurements conducted on an actual HVAC fan module for flow structure identification of possible aeroacoustic noise sources. A major objective of the study was to identity flow structures within the HVAC module that are responsible for noise and in particular "rumble noise" generation. Possible mechanisms for the generation of flow induced noise in the automotive HVAC fan module are also investigated. It is demonstrated that different modes of HVAC operation represent very different internal flow characteristics. This has implications on both fan HVAC airflow performance and noise characteristics. It is demonstrated from principles of complete dynamic similarity that fan scaling laws require that Reynolds, number matching is a necessary condition for developing scale model fans or fan test facilities. The physical basis for the fan scaling laws derived was established from both pure dimensional analysis and also from the fundamental equations of fluid motion. Fan performance was measured in a three times scale model (large scale blower) in air of an actual forward curved automotive HVAC blower. Different fan testing methods (based on AMCA fan test codes) were compared on the basis of static pressure measurements. Also, the flow through an actual HVAC

  2. 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.

  3. 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.

  4. 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

  5. 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.

  6. Hydraulic Performance and Mass Transfer Efficiency of Engineering Scale Centrifugal Contactors

    SciTech Connect

    David Meikrantz; Troy Garn; Nick Mann; Jack Law; Terry Todd

    2007-09-01

    Annular centrifugal contactors (ACCs) are being evaluated for process-scale solvent extraction operations in support of Advanced Fuel Cycle Initiative (AFCI) separations goals. Process-scale annular centrifugal contactors have the potential for high stage efficiency if properly employed and optimized for the application. Hydraulic performance issues related to flow instability and classical flooding are likely unimportant, especially for units with high throughputs. However, annular mixing increases rapidly with increasing rotor diameter while maintaining a fixed g force at the rotor wall. In addition, for engineering/process-scale contactors, elevated rotor speeds and/or throughput rates, can lead to organic phase foaming at the rotor discharge collector area. Foam buildup in the upper rotor head area can aspirate additional vapor from the contactor housing resulting in a complete loss of separation equilibrium. Variable speed drives are thus desirable to optimize and balance the operating parameters to help ensure acceptable performance. Proper venting of larger contactors is required to balance pressures across individual stages and prevent vapor lock due to foam aspiration.

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

    NASA Astrophysics Data System (ADS)

    Gallier, Kirk

    The most common and costly unexpected post-development gas turbine engine reliability issue is blade failure due to High Cycle Fatigue (HCF). HCF in centrifugal compressors is a coupled nonlinear fluid-structure problem for which understanding of the phenomenological root causes is incomplete. The complex physics of this problem provides significant challenges for Computational Fluid Dynamics (CFD) techniques. Furthermore, the available literature fails to address the flow field associated with the diffuser potential field, a primary cause of forced impeller vibration. Because of the serious nature of HCF, the inadequacy of current design approaches to predict HCF, and the fundamental lack of benchmark experiments to advance the design practices, there exists a need to build a database of information specific to the nature of the diffuser generated forcing function as a foundation for understanding flow induced blade vibratory failure. The specific aim of this research is to address the fundamental nature of the unsteady aerodynamic interaction phenomena inherent in high-speed centrifugal compressors wherein the impeller exit flow field is dynamically modulated by the vaned diffuser potential field or shock structure. The understanding of this unsteady aerodynamic interaction is fundamental to characterizing the impeller forcing function. Unsteady static pressure measurement at several radial and circumferential locations in the vaneless space offer a depiction of pressure field radial decay, circumferential variation and temporal fluctuation. These pressure measurements are coupled with high density, full field measurement of the velocity field within the diffuser vaneless space at multiple spanwise positions. The velocity field and unsteady pressure field are shown to be intimately linked. A strong momentum gradient exiting the impeller is shown to extend well across the vaneless space and interact with the diffuser vane leading edge. The deterministic unsteady

  8. 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.

  9. A high acceleration programmable centrifuge used in purification of myocardial and skeletal muscle myosins.

    PubMed

    Wikman-Coffelt, J; Coffelt, R J

    1981-02-01

    Protein purification can be improved by using high acceleration - deceleraton centrifugation. This study describes a high acceleration programmable centrifuge which reaches 5,000 x g in 3 sec and brakes from 5,000 to 0 x g in 4.3 sec. This study further describes the use of this centrifuge in myosin purification and thus demonstrates that protein purification can be improved by separating particles with a high acceleration - deceleration centrifuge for the following reasons: (1) biological and chemical equilibria are immediately terminated, (2) proteolysis is reduced, (3) working time is decreased, and (4) the native state of labile proteins are better preserved. Rapid acceleration and deceleration is advantageous in reducing centrifugation time for separation of particles because it decreases diffusion time of particles and non-desirable interactions. PMID:6452672

  10. Cavitation performance and flow characteristic in a centrifugal pump with inlet guide vanes

    NASA Astrophysics Data System (ADS)

    Tan, L.; Zha, L.; Cao, S. L.; Wang, Y. C.; Gui, S. B.

    2015-01-01

    The influence of prewhirl regulation by inlet guide vanes (IGVs) on cavitation performance and flow characteristic in a centrifugal pump is investigated. At the impeller inlet, the streamlines are regulated by the IGVs, and the axial velocity distribution is also influenced by the IGVs. Due to the total pressure loss on the IGVs, the cavitation performance of the centrifugal pump degrades. The cavitation area in impeller with IGVs is larger than one without IGVs. The specify values of total pressure loss between the suction pipe inlet and impeller inlet for three cavitation conditions show that the IGVs will generate additional pressure loss, which is related to the IGVs angles and cavitation conditions.

  11. A scale-down mimic for mapping the process performance of centrifugation, depth and sterile filtration.

    PubMed

    Joseph, Adrian; Kenty, Brian; Mollet, Michael; Hwang, Kenneth; Rose, Steven; Goldrick, Stephen; Bender, Jean; Farid, Suzanne S; Titchener-Hooker, Nigel

    2016-09-01

    In the production of biopharmaceuticals disk-stack centrifugation is widely used as a harvest step for the removal of cells and cellular debris. Depth filters followed by sterile filters are often then employed to remove residual solids remaining in the centrate. Process development of centrifugation is usually conducted at pilot-scale so as to mimic the commercial scale equipment but this method requires large quantities of cell culture and significant levels of effort for successful characterization. A scale-down approach based upon the use of a shear device and a bench-top centrifuge has been extended in this work towards a preparative methodology that successfully predicts the performance of the continuous centrifuge and polishing filters. The use of this methodology allows the effects of cell culture conditions and large-scale centrifugal process parameters on subsequent filtration performance to be assessed at an early stage of process development where material availability is limited. Biotechnol. Bioeng. 2016;113: 1934-1941. © 2016 The Authors. Biotechnology and Bioengineering Published by Wiley Periodicals, Inc. PMID:26927621

  12. A scale‐down mimic for mapping the process performance of centrifugation, depth and sterile filtration

    PubMed Central

    Joseph, Adrian; Kenty, Brian; Mollet, Michael; Hwang, Kenneth; Rose, Steven; Goldrick, Stephen; Bender, Jean; Farid, Suzanne S.

    2016-01-01

    ABSTRACT In the production of biopharmaceuticals disk‐stack centrifugation is widely used as a harvest step for the removal of cells and cellular debris. Depth filters followed by sterile filters are often then employed to remove residual solids remaining in the centrate. Process development of centrifugation is usually conducted at pilot‐scale so as to mimic the commercial scale equipment but this method requires large quantities of cell culture and significant levels of effort for successful characterization. A scale‐down approach based upon the use of a shear device and a bench‐top centrifuge has been extended in this work towards a preparative methodology that successfully predicts the performance of the continuous centrifuge and polishing filters. The use of this methodology allows the effects of cell culture conditions and large‐scale centrifugal process parameters on subsequent filtration performance to be assessed at an early stage of process development where material availability is limited. Biotechnol. Bioeng. 2016;113: 1934–1941. © 2016 The Authors. Biotechnology and Bioengineering Published by Wiley Periodicals, Inc. PMID:26927621

  13. High Performance Liquid Chromatography

    NASA Astrophysics Data System (ADS)

    Talcott, Stephen

    High performance liquid chromatography (HPLC) has many applications in food chemistry. Food components that have been analyzed with HPLC include organic acids, vitamins, amino acids, sugars, nitrosamines, certain pesticides, metabolites, fatty acids, aflatoxins, pigments, and certain food additives. Unlike gas chromatography, it is not necessary for the compound being analyzed to be volatile. It is necessary, however, for the compounds to have some solubility in the mobile phase. It is important that the solubilized samples for injection be free from all particulate matter, so centrifugation and filtration are common procedures. Also, solid-phase extraction is used commonly in sample preparation to remove interfering compounds from the sample matrix prior to HPLC analysis.

  14. Novel Designs for Centrifugal Countercurrent chromatography: V. Comparative Studies on Performance of Various Column Configurations.

    PubMed

    Yang, Yi; Gu, Dongyu; Aisa, Haji Akber; Ito, Yoichiro

    2010-01-01

    The conventional toroidal coil in centrifugal countercurrent chromatography has a low level of stationary phase retention, since a half of each helical turn is entirely occupied by the mobile phase. In order to cope with this problem, several new column designs including zigzag, saw-tooth and figure-8 patterns have been introduced and their performance was compared in terms of retention of the stationary phase (Sf), peak resolution (Rs), theoretical plate number (N) and column pressures. Overall results of experiments indicate that the figure-8 column yields the highest Rs when the lower phase is used as the mobile phase. Since the column pressure of all these new columns are much lower than that in the traditional toroidal coil column, the separation efficiency can be improved using a long separation column without a risk of column damage by high back pressure. PMID:21057664

  15. Centrifugally activated bearing for high-speed rotating machinery

    DOEpatents

    Post, Richard F.

    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. 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.

  17. Performance analysis on solid-liquid mixed flow in a centrifugal pump

    NASA Astrophysics Data System (ADS)

    Ning, C.; Wang, Y.

    2016-05-01

    In order to study the solid-liquid mixed flow hydraulic characteristics of centrifugal pump, the Pro/E software was used for three-dimensional modeling of centrifugal pump chamber. By using the computational fluid dynamics software CFX, the numerical simulation calculation of solid-liquid two-phase flow within whole flow passage of centrifugal pump was conducted. Aim at different particle diameters, the Reynolds-averaged N-S equations with the RNG k-Ɛ turbulence model and SIMPLEC algorithm were used to simulate the two-phase flow respectively on the condition of different volume fraction. The influence of internal flow characteristic on pump performance was analyzed. On the conditions of different particle diameter and different volume fraction, the turbulence kinetic energy and particle concentration are analyzed. It can be found that the erosion velocity ratio on the flow channel wall increases along with the increasing of the volume fraction

  18. High-solids centrifuge is a boon and a curse for managing anaerobically digested biosolids.

    PubMed

    Murthy, S; Higgins, M; Chen, Y C; Peot, C; Toffey, W

    2006-01-01

    High-solids centrifugation can reduce the cost of managing or disposing of anaerobically digested biosolids. High-solids centrifuges can increase relative cake solids by as much as 5% DS compared with other dewatering devices, such as belt filter presses, with a resulting 15-20% reduction in overall mass of hauled biosolids. Cost reductions can be similar (15-20%) or more, depending on the type of disposal or management involved. For example, the additional removal of water from the cake increases the energy content in the biosolids, thereby facilitating incineration or heat drying processes. For land application, the benefits are more mixed. As explained in this paper, increases in biosolids odours associated with high-solids centrifuges may increase digestion requirements and may compel producers to transport biosolids to more remote, distant sites, potentially increasing transportation costs. High-solids centrifuges shear anaerobically digested biosolids. The shear results in a net increase in labile protein, an odour precursor. Additionally, high-solids centrifugation also results in the inhibition of methanogenesis, a major mechanism for degradation of organosulphur odours. Therefore, the risks and benefits should both be weighed when considering high-solids centrifuges for land application of anaerobically digested biosolids. PMID:16605038

  19. Axial length influence on the performance of centrifugal impellers

    NASA Astrophysics Data System (ADS)

    Al-Zubaidy, S. N. J.

    1992-12-01

    This article describes a general direct-design method for radial flow impellers (based on a prescribed relative velocity schedule). The design procedure has been used as a systematic means of studying the effects of impeller length along its axis of rotation on performance. This was achieved by analyzing a group of impellers with the same performance requirements, inlet and exit geometry, and meridional profile, but different in the blade-angle distributions. The axial length of each impeller was varied systematically in order to assess its impact on the efficiency. The results have shown that for impellers capable of delivering 1 kg of air/s and having a total-to-total pressure ratio of 6:1, there is a specific region of axial length band where the highest efficiency for all designs were calculated and found to vary between 37-49 mm (the measured axial length does not include the disk thickness).

  20. Numerical identification of blade exit angle effect on the performance for a multistage centrifugal pump impeller

    NASA Astrophysics Data System (ADS)

    Babayigit, Osman; Kocaaslan, Osman; Hilmi Aksoy, Muharrem; Melih Guleren, Kursad; Ozgoren, Muammer

    2015-05-01

    Nowadays, single and multistage centrifugal pumps are widely used in industrial and mining enterprises. One of the most important components of a centrifugal pump is the impeller. The performance characteristics are related to the pump comprising the head and the overall efficiency rely a great deal on the impeller geometry. In this work, effects of blade exit angle change on hydraulic efficiency of a multi stage pump impeller are investigated via Ansys-Fluent computational fluid dynamics software for constant width impeller entrance and exit gates, blade numbers and blade thickness. Firstly, the flow volume of a centrifugal pump impeller is generated and then mesh structure is formed for the full impeller flow volume. Secondly, rotational periodic flow model are adopted in order to examine the effect of periodic flow assumption on the performance predictions. Corresponding to the available experimental data, inlet mass flow rate, outlet static pressure and rotation of impeller are taken as 0.02m3s-1, 450 kPa and 2950 rpm, respectively for the water fluid. No slip boundary condition is exposed to all solid of surface in the flow volume. The continuity and Navier-Stokes equations with the k-ɛ turbulence model and the standard wall functions are used. During the study, numerical analyses are conducted for the blade exit angle values of 18°, 20°, 25°, 30° and 35°. In consequence of the performed analyses, it is determined that hydraulic efficiency of the pump impeller value is changed between 81.0-84.6%. The most convenient blade exit angle that yields 84.6% hydraulic efficiency at is 18°. The obtained results show that the blade exit angle range has an impact on the centrifugal pump performance describing the pump head and the hydraulic efficiency.

  1. Cost/performance comparison between pulse columns and centrifugal contactors designed to process Clinch River Breeder Reactor fuel

    SciTech Connect

    Ciucci, J.A. Jr.

    1983-12-01

    A comparison between pulse columns and centrifugal contactors was made to determine which type of equipment was more advantageous for use in the primary decontamination cycle of a remotely operated fuel reprocessing plant. Clinch River Breeder Reactor (CRBR) fuel was chosen as the fuel to be processed in the proposed 1 metric tonne/day reprocessing facility. The pulse columns and centrifugal contactors were compared on a performance and total cost basis. From this comparison, either the pulse columns or the centrifugal contactors will be recommended for use in a fuel reprocessing plant built to reprocess CRBR fuel. The reliability, solvent exposure to radiation, required time to reach steady state, and the total costs were the primary areas of concern for the comparison. The pulse column units were determined to be more reliable than the centrifugal contactors. When a centrifugal contactor motor fails, it can be remotely changed in less than one eight hour shift. Pulse columns expose the solvent to approximately five times as much radiation dose as the centrifugal contactor units; however, the proposed solvent recovery system adequately cleans the solvent for either case. The time required for pulse columns to reach steady state is many times longer than the time required for centrifugal contactors to reach steady state. The cost comparison between the two types of contacting equipment resulted in centrifugal contactors costing 85% of the total cost of pulse columns when the contactors were stacked on three levels in the module. If the centrifugal contactors were all positioned on the top level of a module with the unoccupied volume in the module occupied by other equipment, the centrifugal contactors cost is 66% of the total cost of pulse columns. Based on these results, centrifugal contactors are recommended for use in a remotely operated reprocessing plant built to reprocess CRBR fuel.

  2. High separative power vacuum arc centrifuge (HSP-VAC)

    SciTech Connect

    Qi, Niansheng; Krishnan, M.

    1997-12-01

    The reliability of supply of stable isotopes needed in medicine and science has been a problem for decades. Among the many sources of enriched stable isotopes are the Calutrons at Oak Ridge National Laboratory, ICONS of Cambridge Isotopes Limited, and reactors such as at Atomic Energy of Canada Ltd. and elsewhere. Alameda Applied Sciences Corporation (AASC) staff have spearheaded the development of a new type of isotope separator, dubbed the Vacuum Arc Centrifuge (VAC). This effort dates to the 1980s under National Science Foundation sponsorship at Yale, the early 1990s under a U.S. Department of Energy grant, and more recently, under AASC internal funding. The VAC consists of a vacuum arc discharge between a metal cathode (containing the substances to be separated) and a mesh anode across a small gap.

  3. Effect of double air injection on performance characteristics of centrifugal compressor

    NASA Astrophysics Data System (ADS)

    Hirano, Toshiyuki; Takano, Mizuki; Tsujita, Hoshio

    2015-02-01

    In the operation of a centrifugal compressor of turbocharger, instability phenomena such as rotating stall and surge are induced at a lower flow rate close to the maximum pressure ratio. In this study, for the suppression of surge phenomenon resulting in the extension of the stable operating range of centrifugal compressor to lower flow rate, the compressed air at the compressor exit was re-circulated and injected into the impeller inlet by using the double injection nozzle system. The experiments were performed to find out the optimum circumferential position of the second nozzle relative to the fixed first one and the optimum inner diameter of the injection nozzles, which are able to most effectively reduce the flow rate of surge inception. Moreover, in order to examine the universality of these optimum values, the experiments were carried out for two types of compressors.

  4. Hydraulic performance of a low specific speed centrifugal pump with Spanwise-Slotted Blades

    NASA Astrophysics Data System (ADS)

    Ye, D. X.; Li, H.; Wang, Y.

    2013-12-01

    The hydraulic efficiency of a low specific speed centrifugal pump is low because of the long and narrow meridian flow passage, and the severe disk friction. Spanwise slotted blade flow control technology has been applied to the low specific speed centrifugal pump. This paper concluded that spanwise slotted blades can improve the pump performance in both experiments and simulations. In order to study the influence to the impeller and volute by spanwise slotted blade, impeller efficiency and volute efficiency were defined. The minimum volute efficiency and the maximum pump efficiency appear at the same time in the design flow condition in the unsteady simulation. The mechanism of spanwise slotted blade flow control technology should be researched furthermore.

  5. Numerical performance evaluation of design modifications on a centrifugal pump impeller running in reverse mode

    NASA Astrophysics Data System (ADS)

    Kassanos, Ioannis; Chrysovergis, Marios; Anagnostopoulos, John; Papantonis, Dimitris; Charalampopoulos, George

    2016-06-01

    In this paper the effect of impeller design variations on the performance of a centrifugal pump running as turbine is presented. Numerical simulations were performed after introducing various modifications in the design for various operating conditions. Specifically, the effects of the inlet edge shape, the meridional channel width, the number of blades and the addition of splitter blades on impeller performance was investigated. The results showed that, an increase in efficiency can be achieved by increasing the number of blades and by introducing splitter blades.

  6. Effect of a curved duct upstream on performance of small centrifugal compressors for automobile turbochargers

    NASA Astrophysics Data System (ADS)

    Kikuchi, Shigeta; Yamasaki, Nobuhiko; Yamagata, Akihiro

    2013-02-01

    Since the automobile turbochargers are installed in an engine compartment with limited space, the ducts upstream of the turbocharger compressor may be curved in a complex manner. In the present paper, the effect of a curved duct upstream on performance of small centrifugal compressors for automobile turbochargers is discussed. The computational fluid dynamics (CFD) analysis of a turbocharger compressor validated for the compressor model with the straight pipe applied to the compressor with the curved pipe are executed, and the deterioration of the performance for the curved pipe is confirmed. It is also found that the deterioration of compressor performance is caused by the interaction of the secondary flow and the impeller.

  7. Physiological Effects of Acceleration Observed During a Centrifuge Study of Pilot Performance

    NASA Technical Reports Server (NTRS)

    Smedal, Harald A.; Creer, Brent Y.; Wingrove, Rodney C.

    1960-01-01

    An investigation was conducted by the National Aeronautics and Space Administration, Ames Research Center, and the Naval Air Development Center, Aviation Medical Acceleration Laboratory, to study the effects of acceleration on pilot performance and to obtain some meaningful data for use in establishing tolerance to acceleration levels. The flight simulator used in the study was the Johnsville centrifuge operated as a closed loop system. The pilot was required to perform a control task in various sustained acceleration fields typical of those that Might be encountered by a pilot flying an entry vehicle in which he is seated in a forward-facing position. A special restraint system was developed and designed to increase the pilot's tolerance to these accelerations. The results of this study demonstrated that a well-trained subject, such as a test pilot, can adequately carry out a control task during moderately high accelerations for prolonged periods of time. The maximum levels of acceleration tolerated were approximately 6 times that of gravity for approximately 6 minutes, and varied slightly with the acceleration direction. The tolerance runs were in each case terminated by the subject. In all but two instances, the cause was extreme fatigue. On two occasions the subject terminated the run when he "grayed out." Although there were subjective and objective findings involving the visual and cardiovascular systems, the respiratory system yielded the more critical limiting factors. It would appear that these limiting factors were less severe during the "eyeballs-out" accelerations when compared with the "eyeballs-in" accelerations. These findings are explained on the basis of the influence that the inertial forces of acceleration have on the mechanics of respiration. A condensed version of this report was presented at the Annual Meeting of the Aerospace Medical Association, Miami Beach, May 5-11, 1960, in a paper entitled "Ability of Pilots to Perform a Control Task in

  8. Performance of a small centrifugal pump in He I and He II

    NASA Technical Reports Server (NTRS)

    Ludtke, P. R.; Daney, D. E.; Steward, W. G.

    1988-01-01

    The performance characteristics of a small centrifugal pump in He I and He II are determined over the temperature range of 1.6 to 4.2 K. The single-stage pump is powered by a close-coupled cryogenic induction motor. In the absence of cavitation, pump performance (head and capacity) was found to be identical for He I and He II. Developed heads up to 16 m and capacities of up to 900 liters/hr are obtained at 7000 rpm. A three-blade screw inducer was shown to require much less suction head than a six-blade propeller inducer.

  9. Centrifugal acceleration at high altitudes above the polar cap: A Monte Carlo simulation

    NASA Astrophysics Data System (ADS)

    Abudayyeh, H. A.; Barghouthi, I. A.; Slapak, R.; Nilsson, H.

    2015-08-01

    A Monte Carlo simulation was used to study the outflow of O+ and H+ ions along three flight trajectories above the polar cap up to altitudes of about 15 RE. Barghouthi (2008) developed a model on the basis of altitude and velocity-dependent wave-particle interactions and a radial geomagnetic field which includes the effects of ambipolar electric field and gravitational and mirror forces. In the present work we improve this model to include the effect of the centrifugal force, with the use of relevant boundary conditions. In addition, the magnetic field and flight trajectories, namely, the central polar cap (CPC), nightside polar cap (NPC), and cusp, were calculated using the Tsyganenko T96 model. To simulate wave-particle interactions, the perpendicular velocity diffusion coefficients for O+ ions in each region were determined such that the simulation results fit the observations. For H+ ions, a constant perpendicular velocity diffusion coefficient was assumed for all altitudes in all regions as recommended by Nilsson et al. (2013). The effect of centrifugal acceleration was simulated by considering three values for the ionospheric electric field: 0 (no centrifugal acceleration), 50, and 100 mV/m. It was found that the centrifugal acceleration increases the parallel bulk velocity and decreases the parallel and perpendicular temperatures of both ion species at altitudes above about 4 RE. Centrifugal acceleration also increases the temperature anisotropy at high altitudes. At a given altitude, centrifugal acceleration decreases the density of H+ ions while it increases the density of O+ ions. This implies that with higher centrifugal acceleration more O+ ions overcome the potential barrier. It was also found that aside from two exceptions centrifugal acceleration has the same effect on the velocities of both ions. This implies that the centrifugal acceleration is universal for all particles. The parallel bulk velocities at a given value of ionospheric electric field

  10. Dense and Homogeneous Compaction of Fine Ceramic and Metallic Powders: High-Speed Centrifugal Compaction Process

    NASA Astrophysics Data System (ADS)

    Suzuki, Hiroyuki Y.

    2008-02-01

    High-Speed Centrifugal Compaction Process (HCP) is a variation of colloidal compacting method, in which the powders sediment under huge centrifugal force. Compacting mechanism of HCP differs from conventional colloidal process such as slip casting. The unique compacting mechanism of HCP leads to a number of characteristics such as a higher compacting speed, wide applicability for net shape formation, flawless microstructure of the green compacts, etc. However, HCP also has several deteriorative characteristics that must be overcome to fully realize this process' full potential.

  11. Dense and Homogeneous Compaction of Fine Ceramic and Metallic Powders: High-Speed Centrifugal Compaction Process

    SciTech Connect

    Suzuki, Hiroyuki Y.

    2008-02-15

    High-Speed Centrifugal Compaction Process (HCP) is a variation of colloidal compacting method, in which the powders sediment under huge centrifugal force. Compacting mechanism of HCP differs from conventional colloidal process such as slip casting. The unique compacting mechanism of HCP leads to a number of characteristics such as a higher compacting speed, wide applicability for net shape formation, flawless microstructure of the green compacts, etc. However, HCP also has several deteriorative characteristics that must be overcome to fully realize this process' full potential.

  12. Highly Efficient and Scalable Separation of Semiconducting Carbon Nanotubes via Weak Field Centrifugation.

    PubMed

    Reis, Wieland G; Weitz, R Thomas; Kettner, Michel; Kraus, Alexander; Schwab, Matthias Georg; Tomović, Željko; Krupke, Ralph; Mikhael, Jules

    2016-01-01

    The identification of scalable processes that transfer random mixtures of single-walled carbon nanotubes (SWCNTs) into fractions featuring a high content of semiconducting species is crucial for future application of SWCNTs in high-performance electronics. Herein we demonstrate a highly efficient and simple separation method that relies on selective interactions between tailor-made amphiphilic polymers and semiconducting SWCNTs in the presence of low viscosity separation media. High purity individualized semiconducting SWCNTs or even self-organized semiconducting sheets are separated from an as-produced SWCNT dispersion via a single weak field centrifugation run. Absorption and Raman spectroscopy are applied to verify the high purity of the obtained SWCNTs. Furthermore SWCNT - network field-effect transistors were fabricated, which exhibit high ON/OFF ratios (10(5)) and field-effect mobilities (17 cm(2)/Vs). In addition to demonstrating the feasibility of high purity separation by a novel low complexity process, our method can be readily transferred to large scale production. PMID:27188435

  13. Highly Efficient and Scalable Separation of Semiconducting Carbon Nanotubes via Weak Field Centrifugation

    NASA Astrophysics Data System (ADS)

    Reis, Wieland G.; Weitz, R. Thomas; Kettner, Michel; Kraus, Alexander; Schwab, Matthias Georg; Tomović, Željko; Krupke, Ralph; Mikhael, Jules

    2016-05-01

    The identification of scalable processes that transfer random mixtures of single-walled carbon nanotubes (SWCNTs) into fractions featuring a high content of semiconducting species is crucial for future application of SWCNTs in high-performance electronics. Herein we demonstrate a highly efficient and simple separation method that relies on selective interactions between tailor-made amphiphilic polymers and semiconducting SWCNTs in the presence of low viscosity separation media. High purity individualized semiconducting SWCNTs or even self-organized semiconducting sheets are separated from an as-produced SWCNT dispersion via a single weak field centrifugation run. Absorption and Raman spectroscopy are applied to verify the high purity of the obtained SWCNTs. Furthermore SWCNT - network field-effect transistors were fabricated, which exhibit high ON/OFF ratios (105) and field-effect mobilities (17 cm2/Vs). In addition to demonstrating the feasibility of high purity separation by a novel low complexity process, our method can be readily transferred to large scale production.

  14. Highly Efficient and Scalable Separation of Semiconducting Carbon Nanotubes via Weak Field Centrifugation

    PubMed Central

    Reis, Wieland G.; Weitz, R. Thomas; Kettner, Michel; Kraus, Alexander; Schwab, Matthias Georg; Tomović, Željko; Krupke, Ralph; Mikhael, Jules

    2016-01-01

    The identification of scalable processes that transfer random mixtures of single-walled carbon nanotubes (SWCNTs) into fractions featuring a high content of semiconducting species is crucial for future application of SWCNTs in high-performance electronics. Herein we demonstrate a highly efficient and simple separation method that relies on selective interactions between tailor-made amphiphilic polymers and semiconducting SWCNTs in the presence of low viscosity separation media. High purity individualized semiconducting SWCNTs or even self-organized semiconducting sheets are separated from an as-produced SWCNT dispersion via a single weak field centrifugation run. Absorption and Raman spectroscopy are applied to verify the high purity of the obtained SWCNTs. Furthermore SWCNT - network field-effect transistors were fabricated, which exhibit high ON/OFF ratios (105) and field-effect mobilities (17 cm2/Vs). In addition to demonstrating the feasibility of high purity separation by a novel low complexity process, our method can be readily transferred to large scale production. PMID:27188435

  15. Performance improvement of a centrifugal compressor stage by using different vaned diffusers

    NASA Astrophysics Data System (ADS)

    Zhang, Y. C.; Kong, X. Z.; Li, F.; Sun, W.; Chen, Q. G.

    2013-12-01

    The vaneless diffuser (VLD) is usually adopted in the traditional design of the multi-stage centrifugal compressor because of the stage's match problem. The drawback of the stage with vaneless diffusers is low efficiency. In order to increase the efficiency and at the same time, induce no significant decline in the operating range of the stage, three different types of vaned diffusers are designed and numerically investigated: the traditional vaned diffuser (TVD), the low-solidity cascade diffuser (LSD) and the partial-height vane diffuser (PVD). These three types of vaned diffusers have different influences on the performance of the centrifugal compressor. In the present investigation, the first part investigates the performance of a centrifugal compressor stage with three different vaned diffusers. The second part studies the influences of the height and the position of partial height vanes on the stage performance, and discusses the matching problem between the PVD and the downstream return channel. The stage investigated in this paper includes the impeller, the diffuser, the bend and the return channel. In the process of numerical investigation, the flow is assumed to be steady, and this process includes calculation and simulation. The calculation of 3-D turbulent flow in the stage uses the commercial CFD code NUMECA together with the Spalart-Allmaras turbulence model. The simulation of the computational region includes the impeller passages, the diffuser passages and return channel passages. The structure and surrounding region are assumed to have a perfect cyclic symmetry, so the single channel model and periodic boundary condition are applied at the middle of the passage, that is to reduce the calculation region to only one region. The investigation showed that the low-solidity cascade diffuser would be a better choice as a middle course for the first stage of the multistage centrifugal compressor. Besides, the influences of the height and the position of

  16. Numerical prediction and performance experiment in a deep-well centrifugal pump with different impeller outlet width

    NASA Astrophysics Data System (ADS)

    Shi, Weidong; Zhou, Ling; Lu, Weigang; Pei, Bing; Lang, Tao

    2013-01-01

    The existing research of the deep-well centrifugal pump mainly focuses on reduce the manufacturing cost and improve the pump performance, and how to combine above two aspects together is the most difficult and important topic. In this study, the performances of the deep-well centrifugal pump with four different impeller outlet widths are studied by the numerical, theoretical and experimental methods in this paper. Two stages deep-well centrifugal pump equipped with different impellers are simulated employing the commercial CFD software to solve the Navier-Stokes equations for three-dimensional incompressible steady flow. The sensitivity analyses of the grid size and turbulence model have been performed to improve numerical accuracy. The flow field distributions are acquired and compared under the design operating conditions, including the static pressure, turbulence kinetic energy and velocity. The prototype is manufactured and tested to certify the numerical predicted performance. The numerical results of pump performance are higher than the test results, but their change trends have an acceptable agreement with each other. The performance results indicted that the oversize impeller outlet width leads to poor pump performances and increasing shaft power. Changing the performance of deep-well centrifugal pump by alter impeller outlet width is practicable and convenient, which is worth popularizing in the engineering application. The proposed research enhances the theoretical basis of pump design to improve the performance and reduce the manufacturing cost of deep-well centrifugal pump.

  17. Performance Improvement of a Return Channel in a Multistage Centrifugal Compressor Using Multiobjective Optimization.

    PubMed

    Nishida, Yoshifumi; Kobayashi, Hiromi; Nishida, Hideo; Sugimura, Kazuyuki

    2013-05-01

    The effect of the design parameters of a return channel on the performance of a multistage centrifugal compressor was numerically investigated, and the shape of the return channel was optimized using a multiobjective optimization method based on a genetic algorithm to improve the performance of the centrifugal compressor. The results of sensitivity analysis using Latin hypercube sampling suggested that the inlet-to-outlet area ratio of the return vane affected the total pressure loss in the return channel, and that the inlet-to-outlet radius ratio of the return vane affected the outlet flow angle from the return vane. Moreover, this analysis suggested that the number of return vanes affected both the loss and the flow angle at the outlet. As a result of optimization, the number of return vane was increased from 14 to 22 and the area ratio was decreased from 0.71 to 0.66. The radius ratio was also decreased from 2.1 to 2.0. Performance tests on a centrifugal compressor with two return channels (the original design and optimized design) were carried out using two-stage test apparatus. The measured flow distribution exhibited a swirl flow in the center region and a reversed swirl flow near the hub and shroud sides. The exit flow of the optimized design was more uniform than that of the original design. For the optimized design, the overall two-stage efficiency and pressure coefficient were increased by 0.7% and 1.5%, respectively. Moreover, the second-stage efficiency and pressure coefficient were respectively increased by 1.0% and 3.2%. It is considered that the increase in the second-stage efficiency was caused by the increased uniformity of the flow, and the rise in the pressure coefficient was caused by a decrease in the residual swirl flow. It was thus concluded from the numerical and experimental results that the optimized return channel improved the performance of the multistage centrifugal compressor. PMID:24891759

  18. Influence of blade outlet angle on performance of low-specific-speed centrifugal pump

    NASA Astrophysics Data System (ADS)

    Cui, Baoling; Wang, Canfei; Zhu, Zuchao; Jin, Yingzi

    2013-04-01

    In order to analyze the influence of blade outlet angle on inner flow field and performance of low-specific-speed centrifugal pump, the flow field in the pump with different blade outlet angles 32.5° and 39° was numerically calculated. The external performance experiment was also carried out on the pump. Based on SIMPLEC algorithm, time-average N-S equation and the rectified k-ɛ turbulent model were adopted during the process of computation. The distributions of velocity and pressure in pumps with different blade outlet angles were obtained by calculation. The numerical results show that backflow areas exist in the two impellers, while the inner flow has a little improvement in the impeller with larger blade outlet angle. Blade outlet angle has a certain influence on the static pressure near the long-blade leading edge and tongue, but it has little influence on the distribution of static pressure in the passages of impeller. The experiment results show that the low-specific-speed centrifugal pump with larger blade outlet angle has better hydraulic performance.

  19. The influence of blade profile and slots on the performance of a centrifugal impeller

    NASA Astrophysics Data System (ADS)

    Fowler, H. S.

    1980-01-01

    As part of the program of studies on centrifugal impellers, the problem of instability at low flows was investigated. The major cause was found to be flow detachment from the impeller vanes. Slotted blades were found to be the most effective means of delaying this detachment, and extending the working range of the blower. Low speed studies were confirmed by a test program on a high speed machine, where it was demonstrated that the improved flow range was accompanied by a general increase of efficiency. The design and placement of the slots is discussed.

  20. Effects of measuring positions on the measured aerodynamic performance of a centrifugal compressor

    NASA Astrophysics Data System (ADS)

    Ma, Hongwei; Zhang, Jun

    2010-04-01

    This paper performs a numerical simulation of three-dimensional flow field in a centrifugal compressor with long inlet and outlet pipes using CFX software. By arranging virtual probes at different positions in both inlet and outlet planes, the aerodynamic performance of the centrifugal compressor is measured and compared with each other. Then effects of measuring positions on measurement results are discussed. The results show that it will generate notable measuring errors of the pressure ratio and efficiency if the inlet total pressure is measured using a single-point probe. The inlet total pressure data can be accurate when they are measured using a 3-point rake. The outlet total pressure and total temperature data can not be accurate if they are respectively measured at one circumferential position even using a multi-point rake. Increasing tangential measuring positions at the outlet is effective to improve the test accuracy. When the outlet total pressure and total temperature are respectively measured at 3 tangential positions, the data can be almost accurate.

  1. Effect of discharge duct geometry on centrifugal fan performance and noise emission

    NASA Astrophysics Data System (ADS)

    Nelson, David A.; Butrymowicz, William; Thomas, Christopher

    2005-09-01

    Non-ideal inlet and discharge duct geometries can cause significant changes to both the aerodynamic performance (``fan curve'') and specific sound power emission of a fan. A proper understanding of actual installed performance, as well as a good estimate of the system backpressure curve, is critical to achieving flow and acoustic goals as well as other criteria such as power consumption, mass and volume. To this end a battery of ISO 10302 tests was performed on a blower assembly which supports the Advanced Animal Habitat, being developed by ORBITEC for deployment on the International Space Station. The blower assembly consists of (4) identical centrifugal fans that, amongst themselves and across two prototypes, incorporated several discharge geometries. The inlet geometries were identical in all cases. Thus by comparing the dimensionless pressure-flow and noise emission characteristics across the cases, significant insight into the nature and potential magnitude of these effects is gained.

  2. Design optimization of flow channel and performance analysis for a new-type centrifugal blood pump

    NASA Astrophysics Data System (ADS)

    Ji, J. J.; Luo, X. W.; Y Wu, Q.

    2013-12-01

    In this paper, a new-type centrifugal blood pump, whose impeller is suspended inside a pump chamber with hydraulic bearings, is presented. In order to improve the hydraulic performance of the pump, an internal flow simulation is conducted to compare the effects of different geometrical parameters of pump flow passage. Based on the numerical results, the pumps can satisfy the operation parameters and be free of hemolysis. It is noted that for the pump with a column-type supporter at its inlet, the pump head and hydraulic efficiency decreases compared to the pump with a step-type support structure. The performance drop is caused by the disturbed flow upstream impeller inlet. Further, the unfavorable flow features such as reverse flow and low velocity in the pump may increases the possibility of thrombus. It is also confirmed that the casing shape can little influence pump performance. Those results are helpful for design optimization in blood pump development.

  3. Centrifugal Compressors

    SciTech Connect

    Hastbacka, Mildred; Dieckmann, John; Bouza, Antonio

    2013-02-06

    The article discusses small high speed centrifugal compressors. This topic was covered in a previous ASHRAE Journal column (2003). This article reviews another configuration which has become an established product. The operation, energy savings and market potential of this offering are addressed as well.

  4. Optical Flow-Field Techniques Used for Measurements in High-Speed Centrifugal Compressors

    NASA Technical Reports Server (NTRS)

    Skoch, Gary J.

    1999-01-01

    The overall performance of a centrifugal compressor depends on the performance of the impeller and diffuser as well as on the interactions occurring between these components. Accurate measurements of the flow fields in each component are needed to develop computational models that can be used in compressor design codes. These measurements must be made simultaneously over an area that covers both components so that researchers can understand the interactions occurring between the two components. Optical measurement techniques are being used at the NASA Lewis Research Center to measure the velocity fields present in both the impeller and diffuser of a 4:1 pressure ratio centrifugal compressor operating at several conditions ranging from design flow to surge. Laser Doppler Velocimetry (LDV) was used to measure the intrablade flows present in the impeller, and the results were compared with analyses obtained from two three-dimensional viscous codes. The development of a region of low throughflow velocity fluid within this high-speed impeller was examined and compared with a similar region first observed in a large low-speed centrifugal impeller at Lewis. Particle Image Velocimetry (PIV) is a relatively new technique that has been applied to measuring the diffuser flow fields. PIV can collect data rapidly in the diffuser while avoiding the light-reflection problems that are often encountered when LDV is used. The Particle Image Velocimeter employs a sheet of pulsed laser light that is introduced into the diffuser in a quasi-radial direction through an optical probe inserted near the diffuser discharge. The light sheet is positioned such that its centerline is parallel to the hub and shroud surfaces and such that it is parallel to the diffuser vane, thereby avoiding reflections from the solid surfaces. Seed particles small enough to follow the diffuser flow are introduced into the compressor at an upstream location. A high-speed charge-coupled discharge (CCD) camera is

  5. Performance Investigations of a Large Centrifugal Compressor from an Experimental Turbojet Engine

    NASA Technical Reports Server (NTRS)

    Ginsburg, Ambrose; Creagh, John W. R.; Ritter, William K.

    1948-01-01

    An investigation was conducted on a large centrifugal compressor from an experimental turbojet engine to determine the performance of the compressor and to obtain fundamental information on the aerodynamic problems associated with large centrifugal-type compressors. The results of the research conducted on the compressor indicated that the compressor would not meet the desired engine-design air-flow requirements (78 lb/sec) because of an air-flow restriction in the vaned collector (diffuser). Revision of the vaned collector resulted in an increased air-flow capacity over the speed range and showed improved matching of the impeller and diffuser components. At maximum flow, the original compressor utilized approximately 90 percent of the available geometric throat area at the vaned-collector inlet and the revised compressor utilized approximately 94 percent, regardless of impeller speed. The ratio of the maximum weight flows of the revised and original compressors were less than the ratio of effective critical throat areas of the two compressors because of the large pressure losses in the impeller near the impeller inelt and the difference increased with an increase in impeller speed. In order to further increase the pressure ratio and maximum weight flow of the compressor, the impeller must be modified to eliminate the pressure losses therein.

  6. A prediction of 3-D viscous flow and performance of the NASA low-speed centrifugal compressor

    NASA Technical Reports Server (NTRS)

    Moore, John; Moore, Joan G.

    1989-01-01

    A prediction of the 3-D turbulent flow in the NASA Low-Speed Centrifugal Compressor Impeller has been made. The calculation was made for the compressor design conditions with the specified uniform tip clearance gap. The predicted performance is significantly worse than that predicted in the NASA design study. This is explained by the high tip leakage flow in the present calculation and by the different model adopted for tip leakage flow mixing. The calculation gives an accumulation for high losses in the shroud/pressure-side quadrant near the exit of the impeller. It also predicts a region of meridional backflow near the shroud wall. Both of these flow features should be extensive enough in the NASA impeller to allow detailed flow measurements, leading to improved flow modelling. Recommendations are made for future flow studies in the NASA impeller.

  7. A prediction of 3-D viscous flow and performance of the NASA Low-Speed Centrifugal Compressor

    NASA Technical Reports Server (NTRS)

    Moore, John; Moore, Joan G.

    1990-01-01

    A prediction of the three-dimensional turbulent flow in the NASA Low-Speed Centrifugal Compressor Impeller has been made. The calculation was made for the compressor design conditions with the specified uniform tip clearance gap. The predicted performance is significantly worse than that predicted in the NASA design study. This is explained by the high tip leakage flow in the present calculation and by the different model adopted for tip leakage flow mixing. The calculation gives an accumulation of high losses in the shroud/pressure-side quadrant near the exit of the impeller. It also predicts a region of meridional backflow near the shroud wall. Both of these flow features should be extensive enough in the NASA impeller to allow detailed flow measurements, leading to improved flow modeling. Recommendations are made for future flow studies in the NASA impeller.

  8. An Investigation of Surge in a High-Speed Centrifugal Compressor Using Digital PIV

    NASA Technical Reports Server (NTRS)

    Wernet, Mark P.; Bright, Michelle M.; Skoch, Gary J.

    2002-01-01

    Compressor stall is a catastrophic breakdown of the flow in a compressor, which can lead to a loss of engine power, large pressure transients in the inlet/nacelle and engine flameout. The implementation of active or passive strategies for controlling rotating stall and surge can significantly extend the stable operating range of a compressor without substantially sacrificing performance. It is crucial to identify the dynamic changes occurring in the flow field prior to rotating stall and surge in order to successfully control these events. Generally, pressure transducer measurements are made to capture the transient response of a compressor prior to rotating stall. In this investigation, Digital Particle Imaging Velocimetry (DPIV) is used in conjunction with dynamic pressure transducers to simultaneously capture transient velocity and pressure measurements in the non-stationary flow field during compressor surge. DPIV is an instantaneous, planar measurement technique which is ideally suited for studying transient flow phenomena in high speed turbomachinery and has been used previously to successfully map the stable operating point flow field in the diffuser of a high speed centrifugal compressor. Through the acquisition of both DPIV images and transient pressure data, the time evolution of the unsteady flow during surge is revealed.

  9. Evaluation of the performance of protein separation in figure-8 centrifugal counter-current chromatography

    PubMed Central

    Yang, Yi; Gu, Dongyu; Aisa, Haji Akber; Ito, Yoichiro

    2011-01-01

    The performance of protein separation using the figure-8 column configuration in centrifugal counter-current chromatography was investigated under various flow rates and revolution speeds. The separation was performed with a two-phase solvent system composed of polyethylene glycol 1000/potassium phosphate each at 12.5% (w/w) in water and with lysozyme and myoglobin as test samples. In order to improve tracing of the elution curve, a hollow fiber membrane dialyzer was inserted at the inlet of the UV detector. The results showed that the retention of stationary phase (Sf) and resolution (Rs) increased with decreased flow rate and increased revolution speed. The highest Rs of approximately 1 was obtained at a flow rate of 0.01 mL/min under a revolution speed of 1200 rpm with a 3.4 ml capacity column. PMID:22100551

  10. Centrifuge Study of Pilot Tolerance to Acceleration and the Effects of Acceleration on Pilot Performance

    NASA Technical Reports Server (NTRS)

    Creer, Brent Y.; Smedal, Harald A.; Wingrove, Rodney C.

    1960-01-01

    A research program the general objective of which was to measure the effects of various sustained accelerations on the control performance of pilots, was carried out on the Aviation Medical Acceleration Laboratory centrifuge, U.S. Naval Air Development Center, Johnsville, PA. The experimental setup consisted of a flight simulator with the centrifuge in the control loop. The pilot performed his control tasks while being subjected to acceleration fields such as might be encountered by a forward-facing pilot flying an atmosphere entry vehicle. The study was divided into three phases. In one phase of the program, the pilots were subjected to a variety of sustained linear acceleration forces while controlling vehicles with several different sets of longitudinal dynamics. Here, a randomly moving target was displayed to the pilot on a cathode-ray tube. For each combination of acceleration field and vehicle dynamics, pilot tracking accuracy was measured and pilot opinion of the stability and control characteristics was recorded. Thus, information was obtained on the combined effects of complexity of control task and magnitude and direction of acceleration forces on pilot performance. These tests showed that the pilot's tracking performance deteriorated markedly at accelerations greater than about 4g when controlling a lightly damped vehicle. The tentative conclusion was also reached that regardless of the airframe dynamics involved, the pilot feels that in order to have the same level of control over the vehicle, an increase in the vehicle dynamic stability was required with increases in the magnitudes of the acceleration impressed upon the pilot. In another phase, boundaries of human tolerance of acceleration were established for acceleration fields such as might be encountered by a pilot flying an orbital vehicle. A special pilot restraint system was developed to increase human tolerance to longitudinal decelerations. The results of the tests showed that human tolerance

  11. Testing of a centrifugal blood pump with a high efficiency hybrid magnetic bearing.

    PubMed

    Locke, Dennis H; Swanson, Erik S; Walton, James F; Willis, John P; Heshmat, Hooshang

    2003-01-01

    The purpose of this article is to present test results for a second generation, high efficiency, nonpulsatile centrifugal blood pump that is being developed for use as a left ventricular assist device (LVAD). The LVAD pump uses a hybrid passive-active magnetic bearing support system that exhibits extremely low power loss, low vibration, and high reliability under transient conditions and varying pump orientations. A unique feature of the second generation design configuration is the very simple and direct flow path for both main and washing blood flows. The pump was tested in both vertical and horizontal orientations using a standard flow loop to demonstrate the performance and durability of the second generation LVAD. Steady state and transient orientation pump operating characteristics including pressure, flow, speed, temperatures, vibration, and rotor orientation were measured. During the tests, pump performance was mapped at several operating conditions including points above and below the nominal design of 5 L/min at 100 mm Hg pressure rise. Flow rates from 2 to 7 L/min and pressure rises from 50 to 150 mm Hg were measured. Pump speeds were varied during these tests from 2,500 to 3,500 rpm. The nominal design flow of 5 L/min at 100 mm Hg pressure rise was successfully achieved at the design speed of 3,000 rpm. After LVAD performance testing, both 28 day continuous duty and 5 day transient orientation durability tests were completed without incident. A hydrodynamic backup bearing design feasibility study was also conducted. Results from this design study indicate that an integral hydrodynamic backup bearing may be readily incorporated into the second generation LVAD and other magnetically levitated pump rotors. PMID:14655745

  12. An Investigation of Surge in a High-Speed Centrifugal Compressor Using Digital PIV

    NASA Technical Reports Server (NTRS)

    Wernet, Mark P.; Bright, Michelle M.; Skoch, Gary J.

    2001-01-01

    Compressor stall is a catastrophic breakdown of the flow in a compressor, which con lead to a loss of engine power, large pressure transients in the inlet/nacelle, and engine flameout. The implementation of active or passive strategies for controlling rotating stall and surge can significantly extend the stable operating range of a compressor without substantially sacrificing performance. It is crucial to identify the dynamic changes occurring in the flow field prior to rotating stall and surge in order to control these events successfully. Generally, pressure transducer measurements are made to capture the transient response of a compressor prior to rotating stall. In this investigation, Digital Particle Imaging Velocimetry (DPIV) is used in conjunction with dynamic pressure transducers to capture transient velocity and pressure measurements simultaneously in the nonstationary flow field during compressor surge. DPIV is an instantaneous, planar measurement technique that is ideally suited for studying transient flow phenomena in highspeed turbomachinery and has been used previously to map the stable operating point flow field in the diffuser of a high-speed centrifugal compressor. Through the acquisition of both DPIV images and transient pressure data, the time evolution of the unsteady flow during surge is revealed.

  13. Effects of inlet flow field conditions on the performance of centrifugal compressor diffusers: Part 1 -- Discrete-passage diffuser

    SciTech Connect

    Filipenco, V.G.; Deniz, S.; Johnston, J.M.; Greitzer, E.M.; Cumpsty, N.A.

    2000-01-01

    This is Part 1 of a two-part paper considering the performance of radial diffusers for use in a high-performance centrifugal compressor. Part 1 reports on discrete-passage diffusers, while Part 2 describes a test of a straight-channel diffuser designed for equivalent duty. Two builds of discrete-passage diffuser were tested, with 30 and 38 separate passages. Both the 30 and 38 passage diffusers investigated showed comparable range of unstalled operation and similar level of overall diffuser pressure recovery. The paper concentrates on the influence of inlet flow conditions on the pressure recovery and operating range of radial diffusers for centrifugal compressor stages. The flow conditions examined include diffuser inlet Mach number, flow angle, blockage, and axial flow nonuniformity. The investigation was carried out in a specially built test facility, designed to provide a controlled inlet flow field to the test diffusers. The facility can provide a wide range of diffuser inlet velocity profile distortion and skew with Mach numbers up to unity and flow angles of 63 to 75 deg from the radical direction. The consequences of different averaging methods for the inlet total pressure distributions, which are needed in the definition of diffuser pressure recovery coefficient for nonuniform diffuser inlet conditions, were also assessed. The overall diffuser pressure recovery coefficient, based on suitably averaged inlet total pressure, was found to correlate well with the momentum-averaged flow angle into the diffuser. It is shown that the generally accepted sensitivity of diffuser pressure recovery performance to inlet flow distortion and boundary layer blockage can be largely attributed to inappropriate quantification of the average dynamic pressure at diffuser inlet. Use of an inlet dynamic pressure based on availability or mass-averaging in combination with definition of inlet flow angle based on mass average of the radial and tangential velocity at diffuser inlet

  14. REMOVAL OF SOLIDS FROM HIGHLY ENRICHED URANIUM SOLUTIONS USING THE H-CANYON CENTRIFUGE

    SciTech Connect

    Rudisill, T; Fernando Fondeur, F

    2009-01-15

    Prior to the dissolution of Pu-containing materials in HB-Line, highly enriched uranium (HEU) solutions stored in Tanks 11.1 and 12.2 of H-Canyon must be transferred to provide storage space. The proposed plan is to centrifuge the solutions to remove solids which may present downstream criticality concerns or cause operational problems with the 1st Cycle solvent extraction due to the formation of stable emulsions. An evaluation of the efficiency of the H-Canyon centrifuge concluded that a sufficient amount (> 90%) of the solids in the Tank 11.1 and 12.2 solutions will be removed to prevent any problems. We based this conclusion on the particle size distribution of the solids isolated from samples of the solutions and the calculation of particle settling times in the centrifuge. The particle size distributions were calculated from images generated by scanning electron microscopy (SEM). The mean particle diameters for the distributions were 1-3 {micro}m. A significant fraction (30-50%) of the particles had diameters which were < 1 {micro}m; however, the mass of these solids is insignificant (< 1% of the total solids mass) when compared to particles with larger diameters. It is also probable that the number of submicron particles was overestimated by the software used to generate the particle distribution due to the morphology of the filter paper used to isolate the solids. The settling times calculated for the H-Canyon centrifuge showed that particles with diameters less than 1 to 0.5 {micro}m will not have sufficient time to settle. For this reason, we recommend the use of a gelatin strike to coagulate the submicron particles and facilitate their removal from the solution; although we have no experimental basis to estimate the level of improvement. Incomplete removal of particles with diameters < 1 {micro}m should not cause problems during purification of the HEU in the 1st Cycle solvent extraction. Particles with diameters > 1 {micro}m account for > 99% of the

  15. The change of the inlet geometry of a centrifugal compressor stage and its influence on the compressor performance

    NASA Astrophysics Data System (ADS)

    Wang, Leilei; Yang, Ce; Zhao, Ben; Lao, Dazhong; Ma, Chaochen; Li, Du

    2013-06-01

    The impact on the compressor performance is important for designing the inlet pipe of the centrifugal compressor of a vehicle turbocharger with different inlet pipes. First, an experiment was performed to determine the compressor performance from three cases: a straight inlet pipe, a long bent inlet pipe and a short bent inlet pipe. Next, dynamic sensors were installed in key positions to collect the sign of the unsteady pressure of the centrifugal compressor. Combined with the results of numerical simulations, the total pressure distortion in the pipes, the pressure distributions on the blades and the pressure variability in the diffuser are studied in detail. The results can be summarized as follows: a bent pipe results in an inlet distortion to the compressor, which leads to performance degradation, and the effect is more apparent as the mass flow rate increases. The distortion induced by the bent inlet is not only influenced by the distance between the outlet of the bent section and the leading edge of the impeller but also by the impeller rotation. The flow fields in the centrifugal impeller and the diffuser are influenced by a coupling effect produced by the upstream inlet distortion and the downstream blocking effect from the volute tongue. If the inlet geometry is changed, the distributions and the fluctuation intensities of the static pressure on the main blade surface of the centrifugal impeller and in the diffuser are changed accordingly.

  16. Numerical investigation of the effects of splitter blades on the cavitation performance of a centrifugal pump

    NASA Astrophysics Data System (ADS)

    Zhang, Y. L.; Yuan, S. Q.; Zhang, J. F.; Feng, Y. N.; Lu, J. X.

    2014-03-01

    For the centrifugal pump, additional splitter blades are sometimes necessary in order to improve the head and efficiency. On the other hand, the additional splitter blades will have effect on the cavitation performance due to the changes at the impeller inlet channel. In order to investigate this influence, three impeller schemes were proposed based on a model pump IS50-32-160, one without splitter blades and another two with splitter blades of different inlet diameters. Numerical simulations were carried out to investigate the characteristics of internal flow and the pump cavitation performances at different NPSHA with the CFD technique. The results show that the additional splitter blades will have some positive effect on the pump cavitation performance if the inlet diameter of the splitter blade is properly selected. The reason behind such improvement is that it helps to avoid the flow blocking at the impeller inlet and the vortex cavitation inside the blade passages effectively. For the pump model under our investigation, the cavitation performance reaches its best when the inlet diameter of the splitter blade is 0.725D2.

  17. Effect of diffuser vane shape on the performance of a centrifugal compressor stage

    NASA Astrophysics Data System (ADS)

    Reddy, T. Ch Siva; Ramana Murty, G. V.; Prasad, M. V. S. S. S. M.

    2014-04-01

    The present paper reports the results of experimental investigations on the effect of diffuser vane shape on the performance of a centrifugal compressor stage. These studies were conducted on the chosen stage having a backward curved impeller of 500 mm tip diameter and 24.5 mm width and its design flow coefficient is ϕd=0.0535. Three different low solidity diffuser vane shapes namely uncambered aerofoil, constant thickness flat plate and circular arc cambered constant thickness plate were chosen as the variants for diffuser vane shape and all the three shapes have the same thickness to chord ratio (t/c=0.1). Flow coefficient, polytropic efficiency, total head coefficient, power coefficient and static pressure recovery coefficient were chosen as the parameters for evaluating the effect of diffuser vane shape on the stage performance. The results show that there is reasonable improvement in stage efficiency and total head coefficient with the use of the chosen diffuser vane shapes as compared to conventional vaneless diffuser. It is also noticed that the aero foil shaped LSD has shown better performance when compared to flat plate and circular arc profiles. The aerofoil vane shape of the diffuser blade is seen to be tolerant over a considerable range of incidence.

  18. A compact disk-like centrifugal microfluidic system for high-throughput nanoliter-scale protein crystallization screening.

    PubMed

    Li, Gang; Chen, Qiang; Li, Junjun; Hu, Xiaojian; Zhao, Jianlong

    2010-06-01

    A centrifuge-based microfluidic system has been developed that enables automated high-throughput and low-volume protein crystallizations. In this system, protein solution was automatically and accurately metered and dispensed into nanoliter-sized multiple reaction chambers, and it was mixed with various types of precipitants using a combination of capillary effect and centrifugal force. It has the advantages of simple fabrication, easy operation, and extremely low waste. To demonstrate the feasibility of this system, we constructed a chip containing 24 units and used it to perform lysozyme and cyan fluorescent protein (CyPet) crystallization trials. The results demonstrate that high-quality crystals can be grown and harvested from such a nanoliter-volume microfluidic system. Compared to other microfluidic technologies for protein crystallization, this microfluidic system allows zero waste, simple structure and convenient operation, which suggests that our microfluidic disk can be applied not only to protein crystallization, but also to the miniaturization of various biochemical reactions requiring precise nanoscale control. PMID:20459060

  19. Stability analysis and testing of a train of centrifugal compressors for high pressure gas injection

    SciTech Connect

    Memmott, E.A.

    1999-07-01

    This paper describes the rotor dynamic stability analysis and the PTC-10 Class 1 test of a three body centrifugal compressor train for high pressure natural gas injection services. This train had a full load full pressure string test on hydrocarbon gases to a final discharge pressure of 500 BAR (7250 PSIA). Each compressor is of the back to back configuration, and is equipped with tilting pad seals, damper bearings, and a honeycomb labyrinth at the division wall with shunt holes. The driver is a gas turbine.

  20. Design analysis and performance assessment of hybrid magnetic bearings for a rotary centrifugal blood pump.

    PubMed

    Ren, Zhaohui; Jahanmir, Said; Heshmat, Hooshang; Hunsberger, Andrew Z; Walton, James F

    2009-01-01

    A hybrid magnetic bearing system was designed for a rotary centrifugal blood pump being developed to provide long-term circulatory support for heart failure patients. This design consists of two compact bearings to suspend the rotor in five degrees-of-freedom with single axis active control. Permanent magnets are used to provide passive radial support and electromagnets to maintain axial stability of the rotor. Characteristics of the passive radial and active thrust magnetic bearing system were evaluated by the electromagnetic finite element analysis. A proportional-integral-derivative controller with force balance algorithm was implemented for closed loop control of the magnetic thrust bearing. The control position is continuously adjusted based on the electrical energy in the bearing coils, and thus passive magnetic forces carry static thrust loads to minimize the bearing current. Performance of the magnetic bearing system with associated control algorithm was evaluated at different operating conditions. The bearing current was significantly reduced with the force balance control method and the power consumption was below 0.5 W under various thrust loads. The bearing parameters predicted by the analysis were validated by the experimental data. PMID:19381082

  1. Centrifugal and Axial Pump Design and Off-Design Performance Prediction

    NASA Technical Reports Server (NTRS)

    Veres, Joseph P.

    1995-01-01

    A meanline pump-flow modeling method has been developed to provide a fast capability for modeling pumps of cryogenic rocket engines. Based on this method, a meanline pump-flow code PUMPA was written that can predict the performance of pumps at off-design operating conditions, given the loss of the diffusion system at the design point. The design-point rotor efficiency and slip factors are obtained from empirical correlations to rotor-specific speed and geometry. The pump code can model axial, inducer, mixed-flow, and centrifugal pumps and can model multistage pumps in series. The rapid input setup and computer run time for this meanline pump flow code make it an effective analysis and conceptual design tool. The map-generation capabilities of the code provide the information needed for interfacing with a rocket engine system modeling code. The off-design and multistage modeling capabilities of PUMPA permit the user to do parametric design space exploration of candidate pump configurations and to provide head-flow maps for engine system evaluation.

  2. Numerical simulation and performance prediction in multi-stage submersible centrifugal pump

    NASA Astrophysics Data System (ADS)

    Wang, W. J.; Li, G. D.; Wang, Y.; Cui, Y. R.; Yin, G.; Peng, S.

    2013-12-01

    In order to study the inner flow field of multi-stage submersible centrifugal pump, the model named QD3-60/4-1.1 was selected. Steady turbulence characteristics of impellers, diffusers and return channel were calculated by Fluent software, the SIMPLEC algorithm and RNG κ-ε turbulence model with sliding mesh technology. Then, the distributions of pressure, velocity and Turbulence kinetic energy was obtained and the distributions of velocity field of a channel were analysed. The results show that the static pressure in impeller is increasing with the increasing of radius. The circumferential component of relative velocity is in the opposite direction of impeller rotating. At the same radius, the component value of pressure surface is larger than suction surface. With the increasing of flow rate, absolute velocity and relative velocity flow angle are becoming small, in opposite of the relative velocity and absolute velocity flow angle. The high turbulent zone of impeller is located in the gap of impellers and diffusers. Flow similarity and structure similarity of the multi-stage submersible pump are confirmed.

  3. Disposable magnetically levitated centrifugal blood pump: design and in vitro performance.

    PubMed

    Hoshi, Hideo; Asama, Junichi; Shinshi, Tadahiko; Ohuchi, Katsuhiro; Nakamura, Makoto; Mizuno, Tomohiro; Arai, Hirokuni; Shimokohbe, Akira; Takatani, Setsuo

    2005-07-01

    A magnetically levitated (MagLev) centrifugal blood pump (CBP) with a disposable pump head has been designed to realize a safe, easy-to-handle, reliable, and low-cost extracorporeal blood pump system. It consisted of a radial magnetic-coupled driver with a magnetic bearing having a two-degree freedom control and a disposable pump head unit with a priming volume of 24 mL. The easy on-off disposable pump head unit was made into a three-piece system consisting of the top and bottom housings, and the impeller-rotor assembly. The size and weight of the disposable pump unit were 75 mm x 45 mm and 100 g, respectively. Because the structure of the pump head unit is easily attachable and removable, the gap between the electromagnets of the stator and the target material in the rotor increased to 1.8 mm in comparison to the original integrated bearing system of 1.0 mm. The pump performance, power requirements, and controllability of the magnetic bearing revealed that from 1400 to 2400 rpm, the pump performance remained fairly unchanged. The amplitudes of the X- and Y-axis rotor oscillation increased to +/- 24 microm. The axial displacement of the rotor, 0.4 mm, toward the top housing was also observed at the pump rpm between 1400 and 2400. The axial and rotational stiffness of the bearing were 15.9 N/mm and 4.4 Nm/rad, respectively. The MagLev power was within 0.7 Watts. This study demonstrated the feasibility of a disposable, magnetically suspended CBP as the safe, reliable, easy-to-handle, low-cost extracorporeal circulation support device. PMID:15982279

  4. 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.

  5. Evaluation of a New Remote Handling Design for High Throughput Annular Centrifugal Contactors

    SciTech Connect

    David H. Meikrantz; Troy G. Garn; Jack D. Law; Lawrence L. Macaluso

    2009-09-01

    Advanced designs of nuclear fuel recycling plants are expected to include more ambitious goals for aqueous based separations including; higher separations efficiency, high-level waste minimization, and a greater focus on continuous processes to minimize cost and footprint. Therefore, Annular Centrifugal Contactors (ACCs) are destined to play a more important role for such future processing schemes. Previous efforts defined and characterized the performance of commercial 5 cm and 12.5 cm single-stage ACCs in a “cold” environment. The next logical step, the design and evaluation of remote capable pilot scale ACCs in a “hot” or radioactive environment was reported earlier. This report includes the development of remote designs for ACCs that can process the large throughput rates needed in future nuclear fuel recycling plants. Novel designs were developed for the remote interconnection of contactor units, clean-in-place and drain connections, and a new solids removal collection chamber. A three stage, 12.5 cm diameter rotor module has been constructed and evaluated for operational function and remote handling in highly radioactive environments. This design is scalable to commercial CINC ACC models from V-05 to V-20 with total throughput rates ranging from 20 to 650 liters per minute. The V-05R three stage prototype was manufactured by the commercial vendor for ACCs in the U.S., CINC mfg. It employs three standard V-05 clean-in-place (CIP) units modified for remote service and replacement via new methods of connection for solution inlets, outlets, drain and CIP. Hydraulic testing and functional checks were successfully conducted and then the prototype was evaluated for remote handling and maintenance suitability. Removal and replacement of the center position V-05R ACC unit in the three stage prototype was demonstrated using an overhead rail mounted PaR manipulator. This evaluation confirmed the efficacy of this innovative design for interconnecting and cleaning

  6. Performance, Performance System, and High Performance System

    ERIC Educational Resources Information Center

    Jang, Hwan Young

    2009-01-01

    This article proposes needed transitions in the field of human performance technology. The following three transitions are discussed: transitioning from training to performance, transitioning from performance to performance system, and transitioning from learning organization to high performance system. A proposed framework that comprises…

  7. Bearing gap adjustment for improvement of levitation performance in a hydrodynamically levitated centrifugal blood pump.

    PubMed

    Kosaka, Ryo; Yoshida, Fumihiko; Nishida, Masahiro; Maruyama, Osamu; Kawaguchi, Yasuo; Yamane, Takashi

    2015-01-01

    The purpose of the present study is to investigate a bearing gap adjustment for improvement of levitation performance in a hydrodynamically levitated centrifugal blood pump to realize a blood pump with a low hemolysis level. The impeller levitates axially by balancing a gravitational force, buoyancy, a magnetic force, and hydrodynamic forces on the top and bottom sides of the impeller. To adjust the levitation position of the impeller, the balance of acting forces on the impeller was adjusted by changing the shroud area on the bottom impeller. Three pumps having various shroud area were prepared as tested models: 817 mm(2) (HH-S), 875 mm(2) (HH-M) and 931 mm(2) (HH-L). First, for evaluating the bearing gap adjustment, the bearing gap was estimated by calculating a balancing position of the acting forces on the impeller. We actually measured the gravitational force, buoyancy and the magnetic force, and numerically analyzed hydrodynamic forces on the top and bottom sides of the impeller. Second, to verify accuracy of the estimated bearing gap, the measurement test of the bearing gap was performed. Finally, an in-vitro hemolysis test was performed to evaluate a hemolysis level of the pump. As a result, bottom bearing gaps were estimated as 40 μm (HH-S), 60 μm (HH-M) and 238 μm (HH-L). In the measurement test, bottom bearing gaps were measured as 63 μm (HH-S), 219 μm (HH-M), and 231 μm (HH-L). The estimated bearing gaps had positively correlated with the measured bearing gaps in relation to the shroud area on the impeller. In the hemolysis test, hemolysis level in every model was almost equivalent to that of BPX-80, when the bearing gap was adjusted greater than 60 μm. We could adjust the bearing gap by changing the shroud area on the impeller for improvement of levitation performance to realize a blood pump with a low hemolysis level. PMID:26736996

  8. Stability Improvement of High-Pressure-Ratio Turbocharger Centrifugal Compressor by Asymmetric Flow Control-Part I: Non-Axisymmetrical Flow in Centrifugal Compressor.

    PubMed

    Yang, Mingyang; Zheng, Xinqian; Zhang, Yangjun; Bamba, Takahiro; Tamaki, Hideaki; Huenteler, Joern; Li, Zhigang

    2013-03-01

    This is Part I of a two-part paper documenting the development of a novel asymmetric flow control method to improve the stability of a high-pressure-ratio turbocharger centrifugal compressor. Part I focuses on the nonaxisymmetrical flow in a centrifugal compressor induced by the nonaxisymmetrical geometry of the volute while Part II describes the development of an asymmetric flow control method to avoid the stall on the basis of the characteristic of nonaxisymmetrical flow. To understand the asymmetries, experimental measurements and corresponding numerical simulation were carried out. The static pressure was measured by probes at different circumferential and stream-wise positions to gain insights about the asymmetries. The experimental results show that there is an evident nonaxisymmetrical flow pattern throughout the compressor due to the asymmetric geometry of the overhung volute. The static pressure field in the diffuser is distorted at approximately 90 deg in the rotational direction of the volute tongue throughout the diffuser. The magnitude of this distortion slightly varies with the rotational speed. The magnitude of the static pressure distortion in the impeller is a function of the rotational speed. There is a significant phase shift between the static pressure distributions at the leading edge of the splitter blades and the impeller outlet. The numerical steady state simulation neglects the aforementioned unsteady effects found in the experiments and cannot predict the phase shift, however, a detailed asymmetric flow field structure is obviously obtained. PMID:24891757

  9. Digital PIV Measurements in the Diffuser of a High Speed Centrifugal Compressor

    NASA Technical Reports Server (NTRS)

    Wernet, Mark P.

    1998-01-01

    Particle Imaging Velocimetry (PIV) is a powerful measurement technique which can be used as an alternative or complementary approach to Laser Doppler Velocimetry (LDV) in a wide range of research applications. PIV data are measured simultaneously at multiple points in space, which enables the investigation of the non-stationary spatial structures typically encountered in turbomachinery. Obtaining ample optical access, sufficiently high seed particle concentrations and accurate synchronization of image acquisition relative to impeller position are the most formidable tasks in the successful implementation of PIV in turbomachinery. Preliminary results from the successful application of the standard 2-D digital PIV technique in the diffuser of a high speed centrifugal compressor are presented. Instantaneous flow. measurements were also obtained during compressor surge.

  10. Effect of self recirculation casing treatment on the performance of a turbocharger centrifugal compressor

    NASA Astrophysics Data System (ADS)

    Gancedo, Matthieu

    Increase in emission regulations in the transport industry brings the need to have more efficient engines. A path followed by the automobile industry is to downsize the size of the internal combustion engine and increase the air density at the intake to keep the engine power when needed. Typically a centrifugal compressor is used to force the air into the engine, it can be powered from the engine shaft (superchargers) or extracting energy contained into the hot exhaust gases with a turbine (turbochargers). The flow range of the compressor needs to match the one of the engine. However compressors mass flow operating range is limited by choke on the high end and surge on the low end. In order to extend the operation at low mass flow rates, the use of passive devices for turbocharger centrifugal compressors was explored since the late 80's. Hence, casing treatments including flow recirculation from the inducer part of the compressor have been shown to move the surge limit to lower flows. Yet, the working mechanisms are still not well understood and thus, to optimize the design of this by-pass system, it is necessary to determine the nature of the changes induced by the device both on the dynamic stability of the pressure delivery and on the flow at the inlet. The compressor studied here features a self-recirculating casing treatment at the inlet. The recirculation passage could be blocked to carry a direct comparison between the cases with and without the flow feature. To grasp the effect on compressor stability, pressure measurements were taken in the different constituting elements of the compressor. The study of the mean pressure variations across the operating map showed that the tongue region is a limiting element. Dynamic pressure measurements revealed that the instabilities generated near the inducer when the recirculation is blocked increase the overall instability levels at the compressor outlet and propagating pressure waves starting at the tongue occurred

  11. Lubrication free centrifugal compressor. Technical report

    SciTech Connect

    Gottschlich, J.M.; Scaringe, R.P.; Gui, F.

    1994-04-22

    This paper describes an effort to demonstrate the benefits of an innovative, lightweight, lubrication free centrifugal compressor that allows the use of environmentally sale alternate refrigerants with improved system efficiencies over current state-of-the-art technology. This effort couples the recently developed 3-D high efficiency centrifugal compressor and fabrication technologies with magnetic bearing technology and will then prove the performance, life and reliability of the compressor.

  12. In-Situ Observation of Horizontal Centrifugal Casting using a High-Speed Camera

    NASA Astrophysics Data System (ADS)

    Esaka, Hisao; Kawai, Kohsuke; Kaneko, Hiroshi; Shinozuka, Kei

    2012-07-01

    In order to understand the solidification process of horizontal centrifugal casting, experimental equipment for in-situ observation using transparent organic substance has been constructed. Succinonitrile-1 mass% water alloy was filled in the round glass cell and the glass cell was completely sealed. To observe the movement of equiaxed grains more clearly and to understand the effect of movement of free surface, a high-speed camera has been installed on the equipment. The most advantageous point of this equipment is that the camera rotates with mold, so that one can observe the same location of the glass cell. Because the recording rate could be increased up to 250 frames per second, the quality of movie was dramatically modified and this made easier and more precise to pursue the certain equiaxed grain. The amplitude of oscillation of equiaxed grain ( = At) decreased as the solidification proceeded.

  13. Simultaneous dewatering and reconstitution in a high-gravity solid-bowl centrifuge

    SciTech Connect

    Wen, W.W.; Gray, M.L.; Killmeyer, R.P.; Finseth, D.H.

    1994-12-31

    The Pittsburgh Energy Technology Center has developed a dewatering and reconstitution process in which bitumen emulsion is added to a fine clean coal slurry ahead of the dewatering device. The process simultaneously improves dewatering efficiency and reduces dustiness of the fine coal product during subsequent handling. This paper describes the test results from dewatering and reconstitution of fine coal in a 500 lb. per hour continuous bench scale high-gravity solid-bowl centrifuge in PETC`s Coal Preparation Process Research Facility. Test results will be evaluated in terms of type and dosage of emulsion, product moisture and strength, and product handling and dust reduction efficiency. A preliminary cost analysis will also be included.

  14. 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.

  15. Subsynchronous vibrations in a high pressure centrifugal compressor: A case history

    NASA Technical Reports Server (NTRS)

    Evans, B. F.; Smalley, A. J.

    1984-01-01

    Two distinct aerodynamically excited vibrations in a high pressure low flow centrifugal compressor are documented. A measured vibration near 21% of running speed was identified as a nonresonant forced vibration which results from rotating stall in the diffuser; a measured vibration near 50% of running speed was identified as a self excited vibration sustained by cross coupling forces acting at the compressor wheels. The dependence of these characteristics on speed, discharge pressure, and changes in bearing design are shown. The exciting mechanisms of diffuser stall and aerodynamic cross coupling are evidenced. It is shown how the rotor characteristics are expected to change as a result of modifications. The operation of the compressor after the modifications is described.

  16. Fluid Flow through a High Cell Density Fluidized-Bed during Centrifugal Bioreactor Culture

    PubMed Central

    Detzel, Christopher J.; Van Wie, Bernard J.; Ivory, Cornelius F.

    2010-01-01

    An increasing demand for products such as tissues, proteins, and antibodies from mammalian cell suspension cultures is driving interest in increasing production through high-cell density bioreactors. The centrifugal bioreactor (CCBR) retains cells by balancing settling forces with surface drag forces due to medium throughput and is capable of maintaining cell densities above 108 cells/mL. This article builds on a previous study where the fluid mechanics of an empty CCBR were investigated showing fluid flow is nonuniform and dominated by Coriolis forces, raising concerns about nutrient and cell distribution. In this article, we demonstrate that the previously reported Coriolis forces are still present in the CCBR, but masked by the presence of cells. Experimental dye injection observations during culture of 15 μm hybridoma cells show a continual uniform darkening of the cell bed, indicating the region of the reactor containing cells is well mixed. Simulation results also indicate the cell bed is well mixed during culture of mammalian cells ranging in size from 10 to 20 μm. However, simulations also allow for a slight concentration gradient to be identified and attributed to Coriolis forces. Experimental results show cell density increases from 0.16 to 0.26 when centrifugal force is doubled by increasing RPM from 650 to 920 at a constant inlet velocity of 6.5 cm/s; an effect also observed in the simulation. Results presented in this article indicate cells maintained in the CCBR behave as a high-density fluidized bed of cells providing a homogeneous environment to ensure optimal growth conditions. PMID:20205172

  17. Subjective stress factors in centrifuge training for military aircrews.

    PubMed

    Lin, Pei-Chun; Wang, Jenhung; Li, Shih-Chin

    2012-07-01

    This study investigates stress-influence factors perceived by military aircrews undergoing centrifuge training, which lowers the incidence of G-induced loss of consciousness (G-LOC) for the crews of high-performance combat aircrafts. We used questionnaires to assess the subjective stress-influence factors of crews undergoing centrifuge training. Professionals in aviation physiology identified attributes measuring the perceived stress induced by centrifuge training, which were segmented into three constructs by factor analysis, theory lecture, centrifuge equipment, and physical fitness. Considerable interpenetration was discernible between these factors and military rank, age, length of service, flight hours accrued, and type of aircraft piloted. Identifying and quantifying the perceived stressors experienced in human-use centrifuge training enables aviators, astronauts, and air forces of the world to determine which constructs perceptibly increase or alleviate the perceived stress undergone by trainees when partaking in centrifuge training. PMID:22036449

  18. CENTRIFUGAL SEPARATORS

    DOEpatents

    Skarstrom, C.

    1959-03-10

    A centrifugal separator is described for separating gaseous mixtures where the temperature gradients both longitudinally and radially of the centrifuge may be controlled effectively to produce a maximum separation of the process gases flowing through. Tbe invention provides for the balancing of increases and decreases in temperature in various zones of the centrifuge chamber as the result of compression and expansions respectively, of process gases and may be employed effectively both to neutralize harmful temperature gradients and to utilize beneficial temperaturc gradients within the centrifuge.

  19. Effect of inducer inlet and diffuser throat areas on performance of a low pressure ratio sweptback centrifugal compressor

    NASA Technical Reports Server (NTRS)

    Klassen, H. A.

    1975-01-01

    A low-pressure-ratio centrifugal compressor was tested with nine combinations of three diffuser throat areas and three impeller inducer inlet areas which were 75, 100, and 125 percent of design values. For a given inducer inlet area, increases in diffuser area within the range investigated resulted in increased mass flow and higher peak efficiency. Changes in both diffuser and inducer areas indicated that efficiencies within one point of the maximum efficiency were obtained over a compressor specific speed range of 27 percent. The performance was analyzed of an assumed two-spool open-cycle engine using the 75 percent area inducer with a variable area diffuser.

  20. The Amicon Pro system--a centrifugal device capable of performing all steps in the protein purification workflow.

    PubMed

    Cappione, Amedeo; Mabuchi, Masaharu; Suhrawardy, Saosan; Briggs, David; Nadler, Timothy

    2013-01-01

    raditional protein purification is a long process with many steps utilizing multiple devices, often resulting in protein degradation and loss. The Amicon Pro device streamlines the affinity purification process by providing a single adaptable centrifugation unit capable of performing all steps in the affinity purification process. The device combines affinity-based spin column purification with downstream sample concentration and buffer exchange, eliminating the need for multiple sample transfers, thereby minimizing protein loss. The results presented in this work indicate that purification of His-tagged protein using the Amicon Pro device is faster, easier, and provides better yields than other traditional methods (eg. spin-column and slurry method). PMID:24364216

  1. Feedforward compensation control of rotor imbalance for high-speed magnetically suspended centrifugal compressors using a novel adaptive notch filter

    NASA Astrophysics Data System (ADS)

    Zheng, Shiqiang; Feng, Rui

    2016-03-01

    This paper introduces a feedforward control strategy combined with a novel adaptive notch filter to solve the problem of rotor imbalance in high-speed Magnetically Suspended Centrifugal Compressors (MSCCs). Unbalance vibration force of rotor in MSCC is mainly composed of current stiffness force and displacement stiffness force. In this paper, the mathematical model of the unbalance vibration with the proportional-integral-derivative (PID) control laws is presented. In order to reduce the unbalance vibration, a novel adaptive notch filter is proposed to identify the synchronous frequency displacement of the rotor as a compensation signal to eliminate the current stiffness force. In addition, a feedforward channel from position component to control output is introduced to compensate displacement stiffness force to achieve a better performance. A simplified inverse model of power amplifier is included in the feedforward channel to reject the degrade performance caused by its low-pass characteristic. Simulation and experimental results on a MSCC demonstrate a significant effect on the synchronous vibration suppression of the magnetically suspended rotor at a high speed.

  2. Influence of the Reynolds number on the performance of centrifugal compressors

    NASA Astrophysics Data System (ADS)

    Strub, R. A.; Bonciani, L.; Borer, C. J.; Casey, M. V.; Cole, S. L.

    1987-05-01

    Improved formulas are presented for the correction of the efficiency, the head, and the flow as influenced by the Reynolds number variation between workshop tests and specified conditions, carried out with the same machine. Tests have shown that a sufficiently good correlation between measured and predicted values can be obtained with the proposed formulas. In addition, a proposal is made for the allowable range, taking into account the inherent limitations for accurate testing at low Reynolds numbers. It is recommended that the proposed formulas and allowable range be reviewed by the ASME, the ISO, or any other associations for adoption in revised test codes for centrifugal compressors.

  3. Analysis of the effect of hydrophobic properties of surfaces in the flow part of centrifugal pumps on their operational performance

    NASA Astrophysics Data System (ADS)

    Volkov, A. V.; Parygin, A. G.; Lukin, M. V.; Ryzhenkov, A. V.; Khovanov, G. P.; Naumov, A. V.; Soukal, J.; Pochyly, F.; Fialova, S.

    2015-11-01

    The results of experimental studies focused on evaluating the effect of different conditions of wetting of functional surfaces in flow parts of centrifugal pumps (specifically, impellers) used in heat- and watersupply systems on their operational performance are presented. The conditions of interaction of the pumped medium with the impeller surfaces were altered through hydrophobization of functional surfaces that was implemented using the techniques developed at the Moscow Power Engineering Institute and the Brno University of Technology. It is demonstrated that this hydrophobization produced a considerable positive effect and raised the efficiency of pump units based on centrifugal KM pumps of three different form factors produced by ZAO Pompa (Shchelkovo) and a K centrifugal pump produced by Sigma. The efficiency was increased by 2-6% depending on the pump model. The results of experimental studies of the effect of hydrophobization of the surface of a canonical plate-type domain with a working medium flowing longitudinally along it in a hydrodynamic bed (Moscow Power Engineering Institute) are detailed. Two flat plates with a length of 250 mm and a width of 252 mm were studied. The surfaces of these plates had different roughness values, since one of the plates was polished prior to hydrophobization. Different wetting conditions, which were monitored by measuring the contact angle with a KRUSS MobileDrop goniometer, were established after hydrophobization. The obtained experimental data showed that the surface friction of the modified plate with a higher initial roughness (unpolished plate) was reduced by as much as 23%. This result agrees completely with the Cassie hypothesis.

  4. Study on Internal Flow and External Performance of a Semi-open Impeller Centrifugal Pump with Different Tip Clearances

    NASA Astrophysics Data System (ADS)

    Jia, Xiao-Qi; Cui, Bao-Ling; Zhang, Yu-Liang; Zhu, Zu-Chao

    2015-04-01

    To study the influence of tip clearance on internal flow characteristics and external performance of a prototype centrifugal pump with a semi-open impeller, the unsteady numerical simulation and performance experiments are carried out in this paper. The evolution process of leakage vortex with time t, the flow characteristics and the magnitude of leakage rate in tip clearance are obtained in details. The results indicate that the H-Q curve hump of centrifugal pump shows a weakened trend with the increasing of tip clearance Δc. Meanwhile, the leakage rate ΔQ and the ratio of leakage rate to discharge flow rate (ψ) gradually increase. At the same tip clearance, the leakage rate ΔQ increases, while the ratio of leakage rate to discharge flow rate (ψ) decreases with the increasing of discharge flow rate Q. It is found that higher volumetric loss account for a higher percentage of the total loss at small flow rate condition. There easily exist strong leakage vortexes in the impeller inlet, impeller passage and impeller outlet. The pressure difference between suction side and pressure side makes the fluid pass through the tip clearance layer to form a lower pressure region and leakage vortex.

  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. A compact highly efficient and low hemolytic centrifugal blood pump with a magnetically levitated impeller.

    PubMed

    Asama, Junichi; Shinshi, Tadahiko; Hoshi, Hideo; Takatani, Setsuo; Shimokohbe, Akira

    2006-03-01

    A magnetically levitated (maglev) centrifugal blood pump (CBP), intended for use as a ventricular assist device, needs to be highly durable and reliable for long-term use without any mechanical failure. Furthermore, maglev CBPs should be small enough to be implanted into patients of various size and weight. We have developed a compact maglev CBP employing a two-degree-of-freedom controlled magnetic bearing, with a magnetically suspended impeller directly driven by an internal brushless direct current (DC) motor. The magnetic bearing actively controls the radial motion of the impeller and passively supports axial and angular motions using a permanent magnet embedded in the impeller. The overall dimensions of the maglev CBP are 65 mm in diameter and 40 mm in height. The total power consumption and pump efficiency for pumping 6 L/min against a head pressure of 105 mm Hg were 6.5 W and 21%, respectively. To evaluate the characteristics of the maglev CBP when subjected to a disturbance, excitation of the base, simulating the movement of the patient in various directions, and the sudden interception of the outlet tube connected with the pump in a mock circulatory loop, simulating an unexpected kink and emergent clamp during a heart surgery, were tested by monitoring the five-degree-of-freedom motion of the impeller. Furthermore, the hemolytic characteristics of the maglev CBP were compared with those of the Medtronic Biomedicus BPX-80, which demonstrated the superiority of the maglev CBP. PMID:16480390

  7. Nonlinear free vibrations of centrifugally stiffened uniform beams at high angular velocity

    NASA Astrophysics Data System (ADS)

    Bekhoucha, F.; Rechak, S.; Duigou, L.; Cadou, J. M.

    2016-09-01

    In this paper, we study the bending nonlinear free vibrations of a centrifugally stiffened beam with uniform cross-section and constant angular velocity. The nonlinear intrinsic equations of motion used here are geometrically exact and specific to beams exhibiting large amplitude displacements and rotations associated with small strains. Based on the Timoshenko beam model, these equations are derived from Hamilton's principle, in which the warping is considered. All coupling terms are considered including Coriolis terms. The studied beams are isotropic with clamped-free boundary conditions. By combining the Galerkin method with the harmonic balance method, the equations of motion are converted into a quadratic function treated with a continuation method: the Asymptotic Numerical Method, where the generalized displacement vector is presented as a series expansion. While analysing the effect of the angular velocity, we determine the amplitude versus frequency variations which are plotted as backbone curves. Considering the first lagging and flapping modes, the changes in beam behaviour from hardening to softening are investigated and identified as a function of the angular velocity and the effect of shear. Particular attention is paid to high angular velocities for both Euler-Bernoulli and Timoshenko beams and the natural frequencies so obtained are compared with the results available in the literature.

  8. Effects of volute geometry and impeller orbit on the hydraulic performance of a centrifugal pump

    NASA Technical Reports Server (NTRS)

    Flack, R. D.; Lanes, R. F.

    1983-01-01

    Overall performance data was taken for a Plexiglas water pump with a logarithmic spiral volute and rectangular cross sectioned flow channels. Parametric studies were made in which the center of the impeller was offset from the design center of the volute. The rig was also designed such that the impeller was allowed to synchronously orbit by a fixed amount about any center. The studies indicate that decreasing the tongue clearance decreases the head at low flowrates and increases the head at high flowrates. Also, decreasing the volute area in the first half of the volute and holding the tongue clearance the same, resulted in a decreased head for low flowrates but performance at high flowrates was not affected. Finally, the overall hydraulic performance was not affected by the impeller orbitting about the volute center.

  9. The application and field experience of high strength 12% Cr centrifugally cast pipe for gas gathering system

    SciTech Connect

    Yoshitake, A.; Teraoka, M.; Torigoe, T.; Amako, S.

    1995-10-01

    Centrifugal cast method is one of the processes to provide high quality seamless pipe. The advantages of the process are (1) heavy wall pipe can be manufactured (2) relatively flexible in material selection for manufacturing pipe. For sweet corrosion environment caused by CO{sub 2} where carbon steels can not be used, centrifugally cast 12% Cr martensitic stainless steel pipes and fittings have been developed. One of the key factors of this material applied to pipeline is the weldability, especially high hardness of the welds or its heat affected zone which causes for brittle rupture as well as stress corrosion cracking of the pipeline. Cast 12% Cr pipe which has high strength with low hardness even at the weld joint has been developed. Besides of the development of straight pipe, several types of fittings have been developed. These pipes and fittings have been used for natural gas gathering lines and booster compression lines in sweet corrosion service.

  10. Performance of a low-pressure-ratio centrifugal compressor with four diffuser designs

    NASA Technical Reports Server (NTRS)

    Klassen, H. A.

    1973-01-01

    A low-pressure-ratio centrifugal compressor was tested with four different diffuser configurations. One diffuser had airfoil vanes. Two were pipe diffusers. One pipe diffuser had 7.5 deg cone diffusing passages. The other had trumpet-shaped passages designed for linear static-pressure rise from throat to exit. The fourth configuration had flat vanes with elliptical leading edges similar to those of pipe diffusers. The side walls were contoured to produce a linear pressure rise. Peak compressor efficiencies were 0.82 with the airfoil vane and conical pipe diffusers, 0.80 with the trumpet, and 0.74 with the flat-vane design. Surge margin and useful range were greater for the airfoil-vane diffuser than for the other three.

  11. Centrifuge apparatus

    DOEpatents

    Sartory, Walter K.; Eveleigh, John W.

    1976-01-01

    A method and apparatus for operating a continuous flow blood separation centrifuge are provided. The hematocrit of the entrant whole blood is continuously maintained at an optimum constant value by the addition of plasma to the entrant blood. The hematocrit of the separated red cells is monitored to indicate the degree of separation taking place, thereby providing a basis for regulating the flow through the centrifuge.

  12. Kinetic Simulation of a Centrifugal Bioreactor for High Population Density Hybridoma Culture

    PubMed Central

    Detzel, Christopher J.; Mason, Derek J.; Davis, William C.; Van Wie, Bernard J.

    2009-01-01

    Demand for increasingly complex post-translationally modified proteins, such as monoclonal antibodies (mAbs), necessitates the use of mammalian hosts for production. The focus of this paper is a continuous centrifugal bioreactor (CCBR) capable of increasing volumetric productivity for mAb production through high density hybridoma culture, exceeding 108 cells/mL. At these extreme densities environmental conditions such as substrate and inhibitor concentrations rapidly change, dramatically affecting growth rate. The development of a kinetic model predicting glucose, mAb, lactate, and ammonium concentrations based on dilution rate and cell density is shown in this paper. Additionally, it is found that pH affects both growth rate and viability, and a range of 6.9 to 7.4 is needed to maintain growth rate above 90% of the maximum. Modeling shows that operating an 11.4 mL CCBR inoculated with 2.0 × 107 cells/mL at a dilution rate of 1.3 h−1, results in a predicted growth rate 82% of the maximum value. At the same dilution rate increasing density to 6.0 × 107 cells/mL decreases the predicted growth rate to 60% of the maximum; however, by increasing dilution rate to 6.1 h−1 the growth rate can be increased to 86% of the maximum. Using the kinetic model developed in this research the concentration of glucose, mAb, lactate, and ammonium are all predicted within 13% of experimental results. This model and an understanding of how RPM impacts cell retention serve as valuable tools for maintaining high density CCBR cultures, ensuring maximum growth associated mAb production rates. PMID:19806634

  13. High performance polymer development

    NASA Technical Reports Server (NTRS)

    Hergenrother, Paul M.

    1991-01-01

    The term high performance as applied to polymers is generally associated with polymers that operate at high temperatures. High performance is used to describe polymers that perform at temperatures of 177 C or higher. In addition to temperature, other factors obviously influence the performance of polymers such as thermal cycling, stress level, and environmental effects. Some recent developments at NASA Langley in polyimides, poly(arylene ethers), and acetylenic terminated materials are discussed. The high performance/high temperature polymers discussed are representative of the type of work underway at NASA Langley Research Center. Further improvement in these materials as well as the development of new polymers will provide technology to help meet NASA future needs in high performance/high temperature applications. In addition, because of the combination of properties offered by many of these polymers, they should find use in many other applications.

  14. Computational fluid dynamics analysis of blade tip clearances on hemodynamic performance and blood damage in a centrifugal ventricular assist device.

    PubMed

    Wu, Jingchun; Paden, Bradley E; Borovetz, Harvey S; Antaki, James F

    2010-05-01

    An important challenge facing the design of turbodynamic ventricular assist devices (VADs) intended for long-term support is the optimization of the flow path geometry to maximize hydraulic performance while minimizing shear-stress-induced hemolysis and thrombosis. For unshrouded centrifugal, mixed-flow and axial-flow blood pumps, the complex flow patterns within the blade tip clearance between the lengthwise upper surface of the rotating impeller blades and the stationary pump housing have a dramatic effect on both the hydrodynamic performance and the blood damage production. Detailed computational fluid dynamics (CFD) analyses were performed in this study to investigate such flow behavior in blade tip clearance region for a centrifugal blood pump representing a scaled-up version of a prototype pediatric VAD. Nominal flow conditions were analyzed at a flow rate of 2.5 L/min and rotor speed of 3000 rpm with three blade tip clearances of 50, 100, and 200 microm. CFD simulations predicted a decrease in the averaged tip leakage flow rate and an increase in pump head and axial thrust with decreasing blade tip clearances from 200 to 50 microm. The predicted hemolysis, however, exhibited a unimodal relationship, having a minimum at 100 microm compared to 50 microm and 200 microm. Experimental data corroborate these predictions. Detailed flow patterns observed in this study revealed interesting fluid dynamic features associated with the blade tip clearances, such as the generation and dissipation of tip leakage vortex and its interaction with the primary flow in the blade-blade passages. Quantitative calculations suggested the existence of an optimal blade tip clearance by which hydraulic efficiency can be maximized and hemolysis minimized. PMID:19832736

  15. Computational Fluid Dynamics Analysis of Blade Tip Clearances on Hemodynamic Performance and Blood Damage in a Centrifugal Ventricular Assist Device

    PubMed Central

    Wu, Jingchun; Paden, Bradley E.; Borovetz, Harvey S.; Antaki, James F.

    2011-01-01

    An important challenge facing the design of turbodynamic ventricular assist devices (VADs) intended for long-term support is the optimization of the flow path geometry to maximize hydraulic performance while minimizing shear-stress-induced hemolysis and thrombosis. For unshrouded centrifugal, mixed-flow and axial-flow blood pumps, the complex flow patterns within the blade tip clearance between the lengthwise upper surface of the rotating impeller blades and the stationary pump housing have a dramatic effect on both the hydrodynamic performance and the blood damage production. Detailed computational fluid dynamics (CFD) analyses were performed in this study to investigate such flow behavior in blade tip clearance region for a centrifugal blood pump representing a scaled-up version of a prototype pediatric VAD. Nominal flow conditions were analyzed at a flow rate of 2.5 L/min and rotor speed of 3000 rpm with three blade tip clearances of 50, 100, and 200 μm. CFD simulations predicted a decrease in the averaged tip leakage flow rate and an increase in pump head and axial thrust with decreasing blade tip clearances from 200 to 50 μm. The predicted hemolysis, however, exhibited a unimodal relationship, having a minimum at 100 μm compared to 50 μm and 200 μm. Experimental data corroborate these predictions. Detailed flow patterns observed in this study revealed interesting fluid dynamic features associated with the blade tip clearances, such as the generation and dissipation of tip leakage vortex and its interaction with the primary flow in the blade-blade passages. Quantitative calculations suggested the existence of an optimal blade tip clearance by which hydraulic efficiency can be maximized and hemolysis minimized. PMID:19832736

  16. 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-ε 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.

  17. Computerized rapid high resolution quantitative analysis of plasma lipoproteins based upon single vertical spin centrifugation.

    PubMed

    Cone, J T; Segrest, J P; Chung, B H; Ragland, J B; Sabesin, S M; Glasscock, A

    1982-08-01

    A method has been developed for rapidly quantitating the cholesterol concentration of normal and certain variant lipoproteins in a large number of patients (over 240 in one week). The method employs a microcomputer interfaced to the vertical autoprofiler (VAP) described earlier (Chung et al. 1981. J. Lipid Res. 22: 1003-1014). Software developed to accomplish rapid on-line analysis of the VAP signal uses peak shapes and positions derived from prior VAP analysis of isolated authentic lipoproteins HDL, LDL, and VLDL to quantitate these species in a VAP profile. Variant lipoproteins VHDL (a species with density greater than that of HDL(3)), MDL (a species, most likely Lp(a), with density intermediate between that of HDL and LDL), and IDL are subsequently quantitated by a method combining difference calculations with curve shapes. The procedure has been validated qualitatively by negative stain electron microscopy, gradient gel electrophoresis, strip electrophoresis, chemical analysis of the lipids, radioimmunoassay of the apolipoproteins, and measurement of the density of the peak centers. It has been validated quantitatively by comparison with Lipid Research Clinic methodology for HDL-, LDL-, and VLDL-cholesterol, and for MDL- and IDL-cholesterol by comparison of the amounts of MDL or IDL predicted to be present by the method with that known to be present following standard addition to whole plasma. These validations show that the method is a rapid and accurate technique of lipoprotein analysis suitable for the routine screening of patients for abnormal amounts of normal or variant lipoproteins, as well as for use as a research tool for quantitation of changes in cholesterol content of six or seven different plasma lipoprotein fractions.-Cone, J. T., J. P. Segrest, B. H. Chung, J. B. Ragland, S. M. Sabesin, and A. Glasscock. Computerized rapid high resolution quantitative analysis of plasma lipoproteins based upon single vertical spin centrifugation. PMID:7130860

  18. Protonation-dependent inactivation of Na,K-ATPase by hydrostatic pressure developed at high-speed centrifugation.

    PubMed

    Esmann, M; Fedosova, N U; Maunsbach, A B

    2000-09-29

    Irreversible inactivation of membranous Na,K-ATPase by high-speed centrifugation in dilute aqueous solutions depends markedly on the protonation state of the protein. Pig kidney Na,K-ATPase is irreversibly inactivated at pH 5 but is fully protected at pH 7 and above. Shark rectal gland Na,K-ATPase is irreversibly inactivated at neutral or acidic pH and partially protected at an alkaline pH. The overall Na,K-ATPase activity and the K-dependent pNPPase activity were denatured in parallel. Cryoprotectants such as glycerol or sucrose at concentrations of 25-30% fully protect both enzymes against inactivation. The specific ligands NaCl and KCl protect the Na,K-ATPase activity partially and the pNPPase activity fully at concentrations of 0.2-0.3 M. Electron microscope analysis of the centrifuged Na,K-ATPase membranes revealed that the ultrastructure of the native membranes is preserved upon inactivation. It was also observed that the sarcoplasmic reticulum Ca-ATPase and hog gastric H, K-ATPase are susceptible to inactivation by high-speed centrifugation in a pH-dependent fashion. H,K-ATPase is protected at alkaline pH, whereas Ca-ATPase is protected only in the neutral pH range. PMID:11018676

  19. The effect of prewhirl on the internal aerodynamics and performance of a mixed flow research centrifugal compressor

    NASA Technical Reports Server (NTRS)

    Bryan, William B.; Fleeter, Sanford

    1987-01-01

    The internal three-dimensional steady and time-varying flow through the diffusing elements of a centrifugal impeller were investigated using a moderate scale, subsonic, mixed flow research compressor facility. The characteristics of the test facility which permit the measurement of internal flow conditions throughout the entire research compressor and radial diffuser for various operating conditions are described. Results are presented in the form of graphs and charts to cover a range of mass flow rates with inlet guide vane settings varying from minus 15 degrees to plus 45 degrees. The static pressure distributions in the compressor inlet section and on the impeller and exit diffuser vanes, as well as the overall pressure and temperature rise and mass flow rate, were measured and analyzed at each operating point to determine the overall performance as well as the detailed aerodynamics throughout the compressor.

  20. Performance test results of 80 K centrifugal compressor for helium refrigerator

    SciTech Connect

    Asakura, H.; Kato, D.; Saji, N.; Ohya, H.; Kubota, M.; Kaneko, Y.; Nagai, S.; Toyama, R.

    1994-12-31

    The authors have developed a completely oil-free compressor used for the highly reliable helium refrigeration system for a superconducting generator and carried out performance tests under actual condition. The compressor is designed to achieve a pressure ratio of 8 with only 4 stages by cooling the compressor inlet at 80 K with liquid nitrogen, thus acquiring high reliability of long-term maintenance-free operation together with the use of magnetic bearings for oil-free operation. The compressor at each stage is independently driven by a 25 kW built-in motor at the speed of 100,000 rpm, with the power supplied by a variable frequency inverter. The performance test was carried out at each stage, by incorporating the compressor in the closed loop test equipment using helium gas. It was recognized from the test results that the specified pressure ratio of each stage was achieved at the speed below the rated one of 100,000 rpm. It was found that each stage of the compressor has a flat characteristics of adiabatic efficiency over the wide flow range. The mechanical rotation characteristics at low temperatures was also confirmed to be sufficiently stable.

  1. 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.

  2. Stability Improvement of High-Pressure-Ratio Turbocharger Centrifugal Compressor by Asymmetrical Flow Control-Part II: Nonaxisymmetrical Self-Recirculation Casing Treatment.

    PubMed

    Zheng, Xinqian; Zhang, Yangjun; Yang, Mingyang; Bamba, Takahiro; Tamaki, Hideaki

    2013-03-01

    This is part II of a two-part paper involving the development of an asymmetrical flow control method to widen the operating range of a turbocharger centrifugal compressor with high-pressure ratio. A nonaxisymmetrical self-recirculation casing treatment (SRCT) as an instance of asymmetrical flow control method is presented. Experimental and numerical methods were used to investigate the impact of nonaxisymmetrical SRCT on the surge point of the centrifugal compressor. First, the influence of the geometry of a symmetric SRCT on the compressor performance was studied by means of numerical simulation. The key parameter of the SRCT was found to be the distance from the main blade leading edge to the rear groove (Sr). Next, several arrangements of a nonaxisymmetrical SRCT were designed, based on flow analysis presented in part I. Then, a series of experiments were carried out to analyze the influence of nonaxisymmetrical SRCT on the compressor performance. Results show that the nonaxisymmetrical SRCT has a certain influence on the performance and has a larger potential for stability improvement than the traditional symmetric SRCT. For the investigated SRCT, the surge flow rate of the compressor with the nonaxisymmetrical SRCTs is about 10% lower than that of the compressor with symmetric SRCT. The largest surge margin (smallest surge flow rate) can be obtained when the phase of the largest Sr is coincident with the phase of the minimum static pressure in the vicinity of the leading edge of the splitter blades. PMID:24891758

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

    NASA Astrophysics Data System (ADS)

    Whitley, Stanley

    1984-01-01

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

  4. Investigation of a centrifugal compressor and study of the area ratio and TIP clearance effects on performance

    NASA Astrophysics Data System (ADS)

    Nili-Ahmadabadi, Mahdi; Hajilouy-Benisi, Ali; Durali, Mohammad; Ghadak, Farhad

    2008-12-01

    In this research, the centrifugal compressor of a turbocharger is investigated experimentally and numerically. Performance characteristics of the compressor were obtained experimentally by measurements of rotor speed and flow parameters at the inlet and outlet of the compressor. Three dimensional flow field in the impeller and diffuser was analyzed numerically using a full Navier-Stokes program with SST turbulence model. The performance characteristics of the compressor were obtained numerically, which were then compared with the experimental results. The comparison shows good agreement. Furthermore, the effect of area ratio and tip clearance on the performance parameters and flow field was studied numerically. The impeller area ratio was changed by cutting the impeller exit axial width from an initial value of 4.1 mm to a final value of 5.1 mm, resulting in an area ratio from 0.792 to 0.965. For the rotor with exit axial width of 4.6 mm, performance was investigated for tip clearance of 0.0, 0.5 and 1.0 mm. Results of this simulation at design point showed that the compressor pressure ratio peaked at an area ratio of 0.792 while the efficiency peaked at a higher value of area ratio of 0.878. Also the increment of the tip clearance from 0 to 1 mm resulted in 20 percent efficiency decrease.

  5. High performance systems

    SciTech Connect

    Vigil, M.B.

    1995-03-01

    This document provides a written compilation of the presentations and viewgraphs from the 1994 Conference on High Speed Computing given at the High Speed Computing Conference, {open_quotes}High Performance Systems,{close_quotes} held at Gleneden Beach, Oregon, on April 18 through 21, 1994.

  6. High Performance Polymers

    NASA Technical Reports Server (NTRS)

    Venumbaka, Sreenivasulu R.; Cassidy, Patrick E.

    2003-01-01

    This report summarizes results from research on high performance polymers. The research areas proposed in this report include: 1) Effort to improve the synthesis and to understand and replicate the dielectric behavior of 6HC17-PEK; 2) Continue preparation and evaluation of flexible, low dielectric silicon- and fluorine- containing polymers with improved toughness; and 3) Synthesis and characterization of high performance polymers containing the spirodilactam moiety.

  7. 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.

  8. Centrifugal compressor design for electrically assisted boost

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

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

  9. Evaluation of the Hydraulic Performance and Mass Transfer Efficiency of the CSSX Process with the Optimized Solvent in a Single Stage of 5.5-Cm Diameter Centrifugal Contactor

    SciTech Connect

    Law, J.D.; Tillotson, R.D.; Todd, T.A.

    2002-09-19

    The Caustic-Side Solvent Extraction (CSSX) process has been selected for the separation of cesium from Savannah River Site high-level waste. The solvent composition used in the CSSX process was recently optimized so that the solvent is no longer supersaturated with respect to the calixarene crown ether extractant. Hydraulic performance and mass transfer efficiency testing of a single stage of 5.5-cm ORNL-designed centrifugal contactor has been performed for the CSSX process with the optimized solvent. Maximum throughputs of the 5.5-cm centrifugal contactor, as a function of contactor rotor speed, have been measured for the extraction, scrub, strip, and wash sections of the CSSX flowsheet at the baseline organic/aqueous flow ratios (O/A) of the process, as well as at O/A's 20% higher and 20% lower than the baseline. Maximum throughputs are comparable to the design throughput of the contactor, as well as with throughputs obtained previously in a 5-cm centrifugal contactor with the non-optimized CSSX solvent formulation. The 20% variation in O/A had minimal effect on contactor throughput. Additionally, mass transfer efficiencies have been determined for the extraction and strip sections of the flowsheet. Efficiencies were lower than the process goal of greater than or equal to 80%, ranging from 72 to 75% for the extraction section and from 36 to 60% in the strip section. Increasing the mixing intensity and/or the solution level in the mixing zone of the centrifugal contactor (residence time) could potentially increase efficiencies. Several methods are available to accomplish this including (1) increasing the size of the opening in the bottom of the rotor, resulting in a contactor which is partially pumping instead of fully pumping, (2) decreasing the number of vanes in the contactor, (3) increasing the vane height, or (4) adding vanes on the rotor and baffles on the housing of the contactor. The low efficiency results obtained stress the importance of proper design of

  10. Computational and experimental study of pinch on the performance of a vaneless diffuser in a centrifugal compressor

    NASA Astrophysics Data System (ADS)

    Turunen-Saaresti, T.; Reunanen, A.; Larjola, J.

    2006-12-01

    This study focuses on the vaneless diffuser of a centrifugal compressor. The examined stage consists of an unshrouded impeller, a parallel wall vaneless diffuser and a volute. The walls of the diffuser were movable allowing different pinch configurations to be investigated. The baseline geometry had no pinch i.e. the height of the diffuser was equal to the height of the impeller flow channel plus the axial running clearance. The work consists of both numerical and experimental parts. Quasi-steady, turbulent, fully 3D numerical simulations were conducted. The inlet cone, rotor and diffuser were modelled. Six different configurations were studied. The height of the pinch was altered and the pinch made to different walls was tested. Two of the numerically studied cases were also experimentally investigated. The overall performance of the compressor, the circumferential static and total pressure and the spanwise total pressure distribution before and after the diffuser were measured. The numerical and experimental studies showed that the pinch improved the efficiency of the compressor.

  11. High performance polymeric foams

    SciTech Connect

    Gargiulo, M.; Sorrentino, L.; Iannace, S.

    2008-08-28

    The aim of this work was to investigate the foamability of high-performance polymers (polyethersulfone, polyphenylsulfone, polyetherimide and polyethylenenaphtalate). Two different methods have been used to prepare the foam samples: high temperature expansion and two-stage batch process. The effects of processing parameters (saturation time and pressure, foaming temperature) on the densities and microcellular structures of these foams were analyzed by using scanning electron microscopy.

  12. Performance of two 10-lb/sec centrifugal compressors with different blade and shroud thicknesses operating over a range of Reynolds numbers

    NASA Technical Reports Server (NTRS)

    Skoch, Gary J.; Moore, Royce D.

    1987-01-01

    Centrifugal compressors often cannot be directly scaled to very small flow sizes because of structural and manufacturing limitations. The inability to directly scale all design parameters leads to a performance loss other than that which can be associated with the lower Reynolds number. A 10-lb/sec centrifugal compressor was scaled down to 2-lb/sec where adjustments to blade and shroud thickness and fillet radii were required. The modified 2-lb/sec compressor was then directly scaled back up to 10 lb/sec so that the effect of the modifications could be determined. The performance of the two 10-lb/sec compressors is compared over a range of speed and mass flow. The effect of variations in Reynolds number, impeller tip clearance, and shroud thickness on compressor performance is also presented.

  13. Lightweight Shield for Centrifuge

    NASA Technical Reports Server (NTRS)

    Luper, C.

    1982-01-01

    Centrifuge bowl composed of laminated aluminum offers required combination of high strength at reduced weight. Around outside wall of bowl core of 1/16 inch thick spun aluminum are wrapped two layers of aluminum, each also one-sixteenth inch thick. Layered structure prevents cracks from propagating through wall.

  14. High performance parallel architectures

    SciTech Connect

    Anderson, R.E. )

    1989-09-01

    In this paper the author describes current high performance parallel computer architectures. A taxonomy is presented to show computer architecture from the user programmer's point-of-view. The effects of the taxonomy upon the programming model are described. Some current architectures are described with respect to the taxonomy. Finally, some predictions about future systems are presented. 5 refs., 1 fig.

  15. High-Performance Happy

    ERIC Educational Resources Information Center

    O'Hanlon, Charlene

    2007-01-01

    Traditionally, the high-performance computing (HPC) systems used to conduct research at universities have amounted to silos of technology scattered across the campus and falling under the purview of the researchers themselves. This article reports that a growing number of universities are now taking over the management of those systems and…

  16. Development testing of a magnetic bearing centrifugal chiller

    SciTech Connect

    Benedict, S.M.; Cole, G.S.; Gottschlich, J.

    1998-07-01

    Mainstream Engineering Corporation is developing a lubrication-free centrifugal compressor for high efficiency chiller applications which relies on magnetic bearing technology to support the rotor. This paper presents experimental results of a test program to evaluate the mechanical, thermodynamic, and aerodynamic performance of a high speed, single stage, direct drive centrifugal compressor for chiller applications. The focus is on low capacity centrifugal compressors. The authors present measurements of the compressor efficiency over a wide range of compressor speeds and inlet refrigerant superheat. Measurements show that isentropic efficiencies in excess of 0.80 are attainable over a wide range of operating conditions. This paper also describes a 110 ton chiller which utilizes two such magnetic bearing centrifugal compressors, with HFC-227ea refrigerant, and a user-friendly control system.

  17. High Performance, Dependable Multiprocessor

    NASA Technical Reports Server (NTRS)

    Ramos, Jeremy; Samson, John R.; Troxel, Ian; Subramaniyan, Rajagopal; Jacobs, Adam; Greco, James; Cieslewski, Grzegorz; Curreri, John; Fischer, Michael; Grobelny, Eric; George, Alan; Aggarwal, Vikas; Patel, Minesh; Some, Raphael

    2006-01-01

    With the ever increasing demand for higher bandwidth and processing capacity of today's space exploration, space science, and defense missions, the ability to efficiently apply commercial-off-the-shelf (COTS) processors for on-board computing is now a critical need. In response to this need, NASA's New Millennium Program office has commissioned the development of Dependable Multiprocessor (DM) technology for use in payload and robotic missions. The Dependable Multiprocessor technology is a COTS-based, power efficient, high performance, highly dependable, fault tolerant cluster computer. To date, Honeywell has successfully demonstrated a TRL4 prototype of the Dependable Multiprocessor [I], and is now working on the development of a TRLS prototype. For the present effort Honeywell has teamed up with the University of Florida's High-performance Computing and Simulation (HCS) Lab, and together the team has demonstrated major elements of the Dependable Multiprocessor TRLS system.

  18. High performance steam development

    SciTech Connect

    Duffy, T.; Schneider, P.

    1995-12-31

    DOE has launched a program to make a step change in power plant to 1500 F steam, since the highest possible performance gains can be achieved in a 1500 F steam system when using a topping turbine in a back pressure steam turbine for cogeneration. A 500-hour proof-of-concept steam generator test module was designed, fabricated, and successfully tested. It has four once-through steam generator circuits. The complete HPSS (high performance steam system) was tested above 1500 F and 1500 psig for over 102 hours at full power.

  19. Effects of inlet flow field conditions on the performance of centrifugal compressor diffusers: Part 2 -- Straight-channel diffuser

    SciTech Connect

    Deniz, S.; Greitzer, E.M.; Cumpsty, N.A.

    2000-01-01

    This is Part 2 of an examination of the influence of inlet flow conditions on the performance and operating range of centrifugal compressor vaned diffusers. The paper describes tests of a straight-channel type diffuser, sometimes called a wedge-vane diffuser, and compares the results with those from the discrete-passage diffusers described in Part 1. Effects of diffuser inlet Mach number, flow angle, blockage, and axial flow nonuniformity on diffuser pressure recovery and operating range are addressed. The straight-channel diffuser investigated has 30 vanes and was designed for the same aerodynamic duty as the discrete-passage diffuser described in Part 1. The ranges of the overall pressure recovery coefficients were 0.50--0.78 for the straight-channel diffuser and 0.50--0.70 for the discrete-passage diffuser, except when the diffuser was choked. In other words, the maximum pressure recovery of the straight-channel diffuser was found to be roughly 10% higher than that of the discrete-passage diffuser investigated. The two types of diffuser showed similar behavior regarding the dependence of pressure recovery on diffuser inlet flow angle and the insensitivity of the performance to inlet flow field axial distortion and Mach number. The operating range of the straight-channel diffuser, as for the discrete-passage diffusers, was limited by the onset of rotating stall at a fixed momentum-averaged flow angle into the diffuser, which was for the straight-channel diffuser, {alpha}{sub crit} = 70 {+-} 0.5 deg. The background, nomenclature, and description of the facility and method are all given in Part 1.

  20. 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.

  1. Centrifugal pyrocontactor

    DOEpatents

    Chow, Lorac S.; Leonard, Ralph A.

    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.

  2. 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.

  3. High Performance FORTRAN

    NASA Technical Reports Server (NTRS)

    Mehrotra, Piyush

    1994-01-01

    High performance FORTRAN is a set of extensions for FORTRAN 90 designed to allow specification of data parallel algorithms. The programmer annotates the program with distribution directives to specify the desired layout of data. The underlying programming model provides a global name space and a single thread of control. Explicitly parallel constructs allow the expression of fairly controlled forms of parallelism in particular data parallelism. Thus the code is specified in a high level portable manner with no explicit tasking or communication statements. The goal is to allow architecture specific compilers to generate efficient code for a wide variety of architectures including SIMD, MIMD shared and distributed memory machines.

  4. High Performance Window Retrofit

    SciTech Connect

    Shrestha, Som S; Hun, Diana E; Desjarlais, Andre Omer

    2013-12-01

    The US Department of Energy (DOE) Office of Energy Efficiency and Renewable Energy (EERE) and Traco partnered to develop high-performance windows for commercial building that are cost-effective. The main performance requirement for these windows was that they needed to have an R-value of at least 5 ft2 F h/Btu. This project seeks to quantify the potential energy savings from installing these windows in commercial buildings that are at least 20 years old. To this end, we are conducting evaluations at a two-story test facility that is representative of a commercial building from the 1980s, and are gathering measurements on the performance of its windows before and after double-pane, clear-glazed units are upgraded with R5 windows. Additionally, we will use these data to calibrate EnergyPlus models that we will allow us to extrapolate results to other climates. Findings from this project will provide empirical data on the benefits from high-performance windows, which will help promote their adoption in new and existing commercial buildings. This report describes the experimental setup, and includes some of the field and simulation results.

  5. The Effects of Austenitizing Conditions on the Microstructure and Wear Resistance of a Centrifugally Cast High-Speed Steel Roll

    NASA Astrophysics Data System (ADS)

    Kang, Minwoo; Lee, Young-Kook

    2016-04-01

    The influences of austenitizing conditions on the microstructure and wear resistance of a centrifugally cast high-speed steel roll were investigated through thermodynamic calculation, microstructural analysis, and high-temperature wear tests. When the austenitizing temperature was between 1323 K and 1423 K (1050 °C and 1150 °C), coarse eutectic M2C plates were decomposed into a mixture of MC and M6C particles. However, at 1473 K (1200 °C), the M2C plates were first replaced by both new austenite grains and MC particles without M6C particles, and then remaining M2C particles were dissolved during the growth of MC particles. The wear resistance of the HSS roll was improved with increasing austenitizing temperature up to 1473 K (1200 °C) because the coarse eutectic M2C plates, which are vulnerable to crack propagation, changed to disconnected hard M6C and MC particles.

  6. The Effects of Austenitizing Conditions on the Microstructure and Wear Resistance of a Centrifugally Cast High-Speed Steel Roll

    NASA Astrophysics Data System (ADS)

    Kang, Minwoo; Lee, Young-Kook

    2016-07-01

    The influences of austenitizing conditions on the microstructure and wear resistance of a centrifugally cast high-speed steel roll were investigated through thermodynamic calculation, microstructural analysis, and high-temperature wear tests. When the austenitizing temperature was between 1323 K and 1423 K (1050 °C and 1150 °C), coarse eutectic M2C plates were decomposed into a mixture of MC and M6C particles. However, at 1473 K (1200 °C), the M2C plates were first replaced by both new austenite grains and MC particles without M6C particles, and then remaining M2C particles were dissolved during the growth of MC particles. The wear resistance of the HSS roll was improved with increasing austenitizing temperature up to 1473 K (1200 °C) because the coarse eutectic M2C plates, which are vulnerable to crack propagation, changed to disconnected hard M6C and MC particles.

  7. An experimental and analytical investigation into the performance of centrifugal pumps operating with air-water mixtures

    NASA Astrophysics Data System (ADS)

    Sterrett, John Douglas

    1994-01-01

    An investigation was made into the performance of centrifugal pumps when two-phase non-condensable mixtures of gas and liquid are flowing. This problem is encountered during loss-of-coolant accidents in nuclear reactor systems and in the pumping of oil where natural gas may be present in the mixture. Analytical and experimental techniques were used to address the issues of scaling between a model and a prototype pump and the validity of the single-phase pump affinity laws when two-phase flows are present. The results from this effort have also provided insight into the physical phenomena which cause the degradation in pump performance. An analytical model for the motion of a single bubble through a pump impeller is provided. The results from this fundamental problem show that the Coriolis and buoyancy forces are important in describing the kinematics of a gas phase. These results show that dynamic similitude is not preserved between a model and prototype impeller when the standard single-phase pump scaling relationships are used. The motion of a single bubble is also shown to be influenced by the magnitude of the pump suction pressure. The results from an extensive series of air-water two phase pump tests are provided. A 1/4 scale pump, modeled after the Savannah River Site K-reactor pumps, was tested over a wide range of pump speeds, flow rates, and suction pressures. These results indicate that the single-phase pump affinity laws are not applicable to two-phase pump flows and that the magnitude of the pump suction pressure is an important quantity in determining the pump performance. A second analytical model is developed for two-phase flow through a pump impeller. The results from this one-dimensional, two-fluid, non-homogeneous streamline model show good agreement with the experimental data. The model results support the experimental data in showing that the single-phase pump affinity relationships are not valid for two-phase pump flows and that dynamic

  8. High Performance Buildings Database

    DOE Data Explorer

    The High Performance Buildings Database is a shared resource for the building industry, a unique central repository of in-depth information and data on high-performance, green building projects across the United States and abroad. The database includes information on the energy use, environmental performance, design process, finances, and other aspects of each project. Members of the design and construction teams are listed, as are sources for additional information. In total, up to twelve screens of detailed information are provided for each project profile. Projects range in size from small single-family homes or tenant fit-outs within buildings to large commercial and institutional buildings and even entire campuses. The database is a data repository as well. A series of Web-based data-entry templates allows anyone to enter information about a building project into the database. Once a project has been submitted, each of the partner organizations can review the entry and choose whether or not to publish that particular project on its own Web site.

  9. Waves in Strong Centrifugal Field

    NASA Astrophysics Data System (ADS)

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

    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 polarization 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 modeling 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.

  10. High Performance Work Practices and Firm Performance.

    ERIC Educational Resources Information Center

    Department of Labor, Washington, DC. Office of the American Workplace.

    A literature survey established that a substantial amount of research has been conducted on the relationship between productivity and the following specific high performance work practices: employee involvement in decision making, compensation linked to firm or worker performance, and training. According to these studies, high performance work…

  11. High performance sapphire windows

    NASA Technical Reports Server (NTRS)

    Bates, Stephen C.; Liou, Larry

    1993-01-01

    High-quality, wide-aperture optical access is usually required for the advanced laser diagnostics that can now make a wide variety of non-intrusive measurements of combustion processes. Specially processed and mounted sapphire windows are proposed to provide this optical access to extreme environment. Through surface treatments and proper thermal stress design, single crystal sapphire can be a mechanically equivalent replacement for high strength steel. A prototype sapphire window and mounting system have been developed in a successful NASA SBIR Phase 1 project. A large and reliable increase in sapphire design strength (as much as 10x) has been achieved, and the initial specifications necessary for these gains have been defined. Failure testing of small windows has conclusively demonstrated the increased sapphire strength, indicating that a nearly flawless surface polish is the primary cause of strengthening, while an unusual mounting arrangement also significantly contributes to a larger effective strength. Phase 2 work will complete specification and demonstration of these windows, and will fabricate a set for use at NASA. The enhanced capabilities of these high performance sapphire windows will lead to many diagnostic capabilities not previously possible, as well as new applications for sapphire.

  12. Microfluidic size separation of cells and particles using a swinging bucket centrifuge.

    PubMed

    Yeo, Joo Chuan; Wang, Zhiping; Lim, Chwee Teck

    2015-09-01

    Biomolecular separation is crucial for downstream analysis. Separation technique mainly relies on centrifugal sedimentation. However, minuscule sample volume separation and extraction is difficult with conventional centrifuge. Furthermore, conventional centrifuge requires density gradient centrifugation which is laborious and time-consuming. To overcome this challenge, we present a novel size-selective bioparticles separation microfluidic chip on a swinging bucket minifuge. Size separation is achieved using passive pressure driven centrifugal fluid flows coupled with centrifugal force acting on the particles within the microfluidic chip. By adopting centrifugal microfluidics on a swinging bucket rotor, we achieved over 95% efficiency in separating mixed 20 μm and 2 μm colloidal dispersions from its liquid medium. Furthermore, by manipulating the hydrodynamic resistance, we performed size separation of mixed microbeads, achieving size efficiency of up to 90%. To further validate our device utility, we loaded spiked whole blood with MCF-7 cells into our microfluidic device and subjected it to centrifugal force for a mere duration of 10 s, thereby achieving a separation efficiency of over 75%. Overall, our centrifugal microfluidic device enables extremely rapid and label-free enrichment of different sized cells and particles with high efficiency. PMID:26487900

  13. Large-scale and highly efficient synthesis of micro- and nano-fibers with controlled fiber morphology by centrifugal jet spinning for tissue regeneration

    NASA Astrophysics Data System (ADS)

    Ren, Liyun; Pandit, Vaibhav; Elkin, Joshua; Denman, Tyler; Cooper, James A.; Kotha, Shiva P.

    2013-02-01

    PLLA fibrous tissue scaffolds with controlled fiber nanoscale surface roughness are fabricated with a novel centrifugal jet spinning process. The centrifugal jet spinning technique is a highly efficient synthesis method for micron- to nano-sized fibers with a production rate up to 0.5 g min-1. During the centrifugal jet spinning process, a polymer solution jet is stretched by the centrifugal force of a rotating chamber. By engineering the rheological properties of the polymer solution, solvent evaporation rate and centrifugal force that are applied on the solution jet, polyvinylpyrrolidone (PVP) and poly(l-lactic acid) (PLLA) composite fibers with various diameters are fabricated. Viscosity measurements of polymer solutions allowed us to determine critical polymer chain entanglement limits that allow the generation of continuous fiber as opposed to beads or beaded fibers. Above a critical concentration at which polymer chains are partially or fully entangled, lower polymer concentrations and higher centrifugal forces resulted in thinner fibers. Etching of PVP from the PLLA-PVP composite fibers doped with increasing PVP concentrations yielded PLLA fibers with increasing nano-scale surface roughness and porosity, which increased the fiber hydrophilicity dramatically. Scanning electron micrographs of the etched composite fibers suggest that PVP and PLLA were co-contiguously phase separated within the composite fibers during spinning and nano-scale roughness features were created after the partial etching of PVP. To study the tissue regeneration efficacy of the engineered PLLA fiber matrix, human dermal fibroblasts are used to simulate partial skin graft. Fibers with increased PLLA surface roughness and porosity demonstrated a trend towards higher cell attachment and proliferation.PLLA fibrous tissue scaffolds with controlled fiber nanoscale surface roughness are fabricated with a novel centrifugal jet spinning process. The centrifugal jet spinning technique is a

  14. Preclinical study of a novel hydrodynamically levitated centrifugal pump for long-term cardiopulmonary support : In vivo performance during percutaneous cardiopulmonary support.

    PubMed

    Tsukiya, Tomonori; Mizuno, Toshihide; Takewa, Yoshiaki; Tatsumi, Eisuke; Taenaka, Yoshiyuki

    2015-12-01

    An extracorporeal centrifugal blood pump with a hydrodynamically levitated impeller was developed for use in a durable extracorporeal membrane oxygenation (ECMO) system. The present study examined the biocompatibility of the blood pump during long-term use by conducting a series of 30-day chronic animal experiments. The ECMO system was used to produce a percutaneous venoarterial bypass between the venae cavae and carotid artery in adult goats. No anticoagulation or antiplatelet therapy was administered during the experiments. Three out of four animals survived for the scheduled 30-day period, and the blood pumps and membrane oxygenators both exhibited sufficient hydrodynamic performance and good antithrombogenicity, while one animal died of massive bleeding from the outflow cannulation site. The animals' plasma free hemoglobin had returned to within the normal range by 1 week after the surgical intervention, and their hemodynamic and biochemistry parameters remained within their normal ranges throughout the experiment. The explanted centrifugal blood pumps did not display any trace of thrombus formation. Based on the biocompatibility demonstrated in this study, the examined centrifugal blood pump, which includes a hydrodynamically levitated impeller, is suitable for use in durable ECMO systems. PMID:25975380

  15. Scale-down characterization of post-centrifuge flocculation processes for high-throughput process development

    PubMed Central

    Espuny Garcia del Real, Georgina; Davies, Jim; Bracewell, Daniel G

    2014-01-01

    Abctract Flocculation unit operations are being revisited as a strategy to ease the burden posed on clarification and purification operations by the increasingly high cell density cultures used in the biopharmaceutical industry. The purpose of this study was to determine the key process parameters impacting flocculation scale-up and use this understanding to develop an automated ultra-scale down (USD) method for the rapid characterization of flocculation at the microliter scale. The conditions under which flocculation performance of a non-geometrically similar vessel three orders of magnitude larger can be mimicked by the USD platform are reported. Saccharomyces cerevisiae clarified homogenate was flocculated with poly(ethyleneimine) (PEI) to remove the residual solids remaining in the centrate. Flocculant addition time modulated flocculation performance depending on the predominant mixing time scale (i.e. macro-, meso- or micromixing). Particle growth and breakage was mimicked at the two flocculation scales by the average turbulent energy dissipation (εavg) and impeller tip speed (vtip) scale-up bases. The results obtained were used to develop an USD method. The USD method proposed uses constant εavg as the scale-up basis under a micromixing controlled regime. These conditions mimicked the STR flocculation performance within a ±5% error margin. Operation in the mesomixing regime led to particle size deviations between the flocculation scales of ≤50 %. These results, in addition to the microscopic observations made, demonstrate the USD system presented in this work can produce process-relevant flocculated material at the microliter scale under the correct operating conditions. PMID:24942244

  16. Measuring the performance of a variable-speed drive retrofit on a fixed-speed centrifugal chiller

    SciTech Connect

    Lenarduzzi, F.J.; Yap, S.S.

    1998-12-31

    Variable-speed drives (VSD) offer many advantages in a heating, ventilating, and air-conditioning (HVAC) system. However, they are seldom used with centrifugal chiller systems. One of the reasons for the low number of VSDs in chiller systems is unfamiliarity with these systems. This research project was initiated to establish a base of accurate and detailed information for building owners and HVAC consultants to realize the benefits of VSDs. A 200 hp variable-speed drive was retrofitted to a 615 kW (175 ton) centrifugal chiller and monitored for one cooling season. Results show that VSD retrofits do work in HVAC centrifugal chillers. The VSD operated without problems during the test period and successfully met the air-conditioning requirements of the building. Energy savings are estimated to be approximately 41% at this particular site. The power quality effects also were studied and do not appear to be a concern. The total harmonic distortion is less than 2.5%.

  17. High Performance Work Systems and Firm Performance.

    ERIC Educational Resources Information Center

    Kling, Jeffrey

    1995-01-01

    A review of 17 studies of high-performance work systems concludes that benefits of employee involvement, skill training, and other high-performance work practices tend to be greater when new methods are adopted as part of a consistent whole. (Author)

  18. High Performance Network Monitoring

    SciTech Connect

    Martinez, Jesse E

    2012-08-10

    Network Monitoring requires a substantial use of data and error analysis to overcome issues with clusters. Zenoss and Splunk help to monitor system log messages that are reporting issues about the clusters to monitoring services. Infiniband infrastructure on a number of clusters upgraded to ibmon2. ibmon2 requires different filters to report errors to system administrators. Focus for this summer is to: (1) Implement ibmon2 filters on monitoring boxes to report system errors to system administrators using Zenoss and Splunk; (2) Modify and improve scripts for monitoring and administrative usage; (3) Learn more about networks including services and maintenance for high performance computing systems; and (4) Gain a life experience working with professionals under real world situations. Filters were created to account for clusters running ibmon2 v1.0.0-1 10 Filters currently implemented for ibmon2 using Python. Filters look for threshold of port counters. Over certain counts, filters report errors to on-call system administrators and modifies grid to show local host with issue.

  19. Centrifugally decoupling touchdown bearings

    DOEpatents

    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.

  20. Effects of Alloying Elements on Microstructure, Hardness, Wear Resistance, and Surface Roughness of Centrifugally Cast High-Speed Steel Rolls

    NASA Astrophysics Data System (ADS)

    Ha, Dae Jin; Sung, Hyo Kyung; Park, Joon Wook; Lee, Sunghak

    2009-11-01

    A study was made of the effects of carbon, tungsten, molybdenum, and vanadium on the wear resistance and surface roughness of five high-speed steel (HSS) rolls manufactured by the centrifugal casting method. High-temperature wear tests were conducted on these rolls to experimentally simulate the wear process during hot rolling. The HSS rolls contained a large amount (up to 25 vol pct) of carbides, such as MC, M2C, and M7C3 carbides formed in the tempered martensite matrix. The matrix consisted mainly of tempered lath martensite when the carbon content in the matrix was small, and contained a considerable amount of tempered plate martensite when the carbon content increased. The high-temperature wear test results indicated that the wear resistance and surface roughness of the rolls were enhanced when the amount of hard MC carbides formed inside solidification cells increased and their distribution was homogeneous. The best wear resistance and surface roughness were obtained from a roll in which a large amount of MC carbides were homogeneously distributed in the tempered lath martensite matrix. The appropriate contents of the carbon equivalent, tungsten equivalent, and vanadium were 2.0 to 2.3, 9 to 10, and 5 to 6 pct, respectively.

  1. Optimum design for LRE centrifugal pumps

    NASA Astrophysics Data System (ADS)

    Zhu, Zuchao; Zhang, Guoqian; Sun, Jiren

    1995-05-01

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

  2. Centrifugal membrane filtration -- Task 9

    SciTech Connect

    1996-08-01

    The Energy and Environmental Research Center (EERC) has teamed with SpinTek Membrane Systems, Inc., the developer of a centrifugal membrane filtration technology, to demonstrate applications for the SpinTek technology within the US 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. Membrane-screening tests were performed with the SpinTek STC-X4 static test cell filtration unit, using five ceramic membranes with different pore size and composition. Based on permeate flux, a 0.25-{micro}m TiO{sub 2}/Al{sub 2}O{sub 3} membrane was selected for detailed performance evaluation using the SpinTek ST-IIL centrifugal membrane filtration unit with a surrogate tank waste solution. An extended test run of 100 hr performed on a surrogate tank waste solution showed some deterioration in filtration performance, based on flux, apparently due to the buildup of solids near the inner portion of the membrane where relative membrane velocities were low. Continued testing of the system will focus on modifications to the shear pattern across the entire membrane surface to affect improved long-term performance.

  3. Experimental performance of a 13.65-centimeter-tip-diameter tandem-bladed sweptback centrifugal compressor designed for a pressure ratio of 6

    NASA Technical Reports Server (NTRS)

    Klassen, H. A.; Wood, J. R.; Schumann, L. F.

    1977-01-01

    A 13.65 cm tip diameter backswept centrifugal impeller having a tandem inducer and a design mass flow rate of 0.907 kg/sec was experimentally investigated to establish stage and impeller characteristics. Tests were conducted with both a cascade diffuser and a vaneless diffuser. A pressure ratio of 5.9 was obtained near surge for the smallest clearance tested. Flow range at design speed was 6.3 percent for the smallest clearance test. Impeller exit to shroud axial clearance at design speed was varied to determine the effect on stage and impeller performance.

  4. Centrifuge Facility for the International Space Station Alpha

    NASA Technical Reports Server (NTRS)

    Johnson, Catherine C.; Hargens, Alan R.

    1994-01-01

    The Centrifuge Facility planned for the International Space Station Alpha has under-one considerable redesign over the past year, primarily because the Station is now viewed as a 10 year mission rather than a 30 year mission and because of the need to simply the design to meet budget constraints and a 2000 launch date. The basic elements of the Centrifuge Facility remain the same, i.e., a 2.5 m diameter centrifuge, a micro-g holding unit, plant and animal habitats, a glovebox and a service unit. The centrifuge will still provide the full range of artificial gravity from 0.01 a to 2 - as originally planned; however, the extractor to permit withdrawal of habitats from the centrifuge without stopping the centrifuge has been eliminated. The specimen habitats have also been simplified and are derived from other NASA programs. The Plant Research Unit being developed by the Gravitational Biology Facility will be used to house plants in the Centrifuge Facility. Although not as ambitious as the Centrifuge Facility plant habitat, it will provide much better environmental control and lighting than the current Shuttle based Plant Growth Facility. Similarly, rodents will be housed in the Advanced Animal Habitat being developed for the Shuttle program. The Centrifuge Facility and ISSA will provide the opportunity to perform repeatable, high quality science. The long duration increments available on the Station will permit multigeneration studies on both plants and animals which have not previously been possible. The Centrifuge Facility will accommodate sufficient number of specimens to permit statistically significant sampling of specimens to investigate the time course of adaptation to altered gravity environments. The centrifuge will for the first time permit investigators to use gravity itself as a tool to investigate fundamental processes, to investigate the intensity and duration of gravity to maintain normal structure and function, to separate the effects of micro-g from

  5. Demonstration of the SREX process for the removal of {sup 90}Sr from actual highly radioactive solutions in centrifugal contactors

    SciTech Connect

    Law, J.D.; Wood, D.J.; Todd, T.A.; Olson, L.G.

    1997-10-01

    The SREX process is being evaluated at the Idaho Chemical Processing Plant (ICPP) for the separation of {sup 90}Sr from acidic radioactive wastes stored at the ICPP. These efforts have culminated in a recent demonstration of the SREX process with actual tank waste. This demonstration was performed using 24 stages of 2-cm diameter centrifugal contactors installed in a shielded hot cell at the ICPP Remote Analytical Laboratory. An overall removal efficiency of 99.995% was obtained for {sup 90}Sr. As a result, the activity of {sup 90}Sr was reduced from 201 Ci/m{sup 3} in the feed solution of 0.0089 Ci/m{sup 3} in the aqueous raffinate, which is below the U.S. NRC Class A LLW limit of 0.04 Ci/m{sup 3} for {sup 90}Sr. Lead was extracted by the SREX solvent and successfully partitioned from the {sup 90}Sr using an ammonium citrate strip solution. Additionally, 94% of the total alpha activity, 1.9% of the {sup 241}Am, 99.94% of the {sup 238}Pu, 99.97% of the {sup 239}Pu, 36.4% of the K, 64% of the Ba, and >83% of the Zr were extracted by the SREX solvent. Cs, B, Cd, Ca, Cr, Fe, Mn, Ni, and Na were essentially inextractable. 10 refs., 2 figs., 3 tabs.

  6. Commoditization of High Performance Storage

    SciTech Connect

    Studham, Scott S.

    2004-04-01

    The commoditization of high performance computers started in the late 80s with the attack of the killer micros. Previously, high performance computers were exotic vector systems that could only be afforded by an illustrious few. Now everyone has a supercomputer composed of clusters of commodity processors. A similar commoditization of high performance storage has begun. Commodity disks are being used for high performance storage, enabling a paradigm change in storage and significantly changing the price point of high volume storage.

  7. Oscillatory counter-centrifugation

    NASA Astrophysics Data System (ADS)

    Xu, Shujing; Nadim, Ali

    2016-02-01

    In ordinary centrifugation, a suspended particle that is heavier than the displaced fluid migrates away from the rotation axis when the fluid-filled container rotates steadily about that axis. In contrast a particle that is lighter than the displaced fluid (e.g., a bubble) migrates toward the rotation axis in a centrifuge. In this paper, we show theoretically that if a fluid-filled container rotates in an oscillatory manner as a rigid body about an axis, at high enough oscillation frequencies, the sense of migration of suspended particles is reversed. That is, in that case particles denser than the fluid migrate inward, while those that are lighter than the fluid move outward. We term this unusual phenomenon "Oscillatory Counter-Centrifugation" or OCC, for short. Through application of the method of averaging to the equations of motion, we derive a simple criterion to predict the occurrence of OCC. The analysis also reveals that the time-average of the Coriolis force in the radial direction is the term that is responsible for this effect. In addition, we analyze the effects of the Basset history force and the Rubinow-Keller lift force on particle trajectories and find that OCC persists even when these forces are active. The phenomenon awaits experimental verification.

  8. Performance of 4600-pound-thrust centrifugal-flow-type turbojet engine with water-alcohol injection at inlet

    NASA Technical Reports Server (NTRS)

    Glasser, Philip W

    1950-01-01

    An experimental investigation of the effects of injecting a water-alcohol mixture of 2:1 at the compressor inlet of a centrifugal-flow type turbojet engine was conducted in an altitude test chamber at static sea-level conditions and at an altitude of 20,000 feet with a flight Mach number of 0.78 with an engine operating at rated speed. The net thrust was augmented by 0.16 for both flight conditions with a ratio of injected liquid to air flow of 0.05. Further increases in the liquid-air ratio did not give comparable increases in thrust.

  9. High Performance Computing Today

    SciTech Connect

    Dongarra, Jack; Meuer,Hans; Simon,Horst D.; Strohmaier,Erich

    2000-04-01

    In last 50 years, the field of scientific computing has seen a rapid change of vendors, architectures, technologies and the usage of systems. Despite all these changes the evolution of performance on a large scale however seems to be a very steady and continuous process. Moore's Law is often cited in this context. If the authors plot the peak performance of various computers of the last 5 decades in Figure 1 that could have been called the supercomputers of their time they indeed see how well this law holds for almost the complete lifespan of modern computing. On average they see an increase in performance of two magnitudes of order every decade.

  10. A mock circulatory system to assess the performance of continuous-flow left ventricular assist devices (LVADs): does axial flow unload better than centrifugal LVAD?

    PubMed

    Sénage, Thomas; Février, Dorothée; Michel, Magali; Pichot, Emmanuel; Duveau, Daniel; Tsui, Steven; Trochu, Jean Noel; Roussel, Jean Christian

    2014-01-01

    Hemodynamic performances comparisons between different types of left ventricular assist devices (LVADs) remain difficult in a clinical context. The aim of this study was to create an experimental model to assess and compare two types of LVAD under hemodynamic conditions that simulated physical effort and pulmonary hypertension. An experimental mock circulatory system was created to simulate the systemic and pulmonary circulations and consisted of pulsatile left and right cardiac simulators (cardiowest pump), air/water tanks to model compliances, and tubes to model the venous and arterial resistances. Two types of continuous-flow ventricular assist devices were connected to this pulsated model: an axial flow pump, Heartmate II (HTM II), and a centrifugal pump, VentrAssist (VTA). The hemodynamic conditions at rest and during exercise were replicated. Mean aortic pressures were not significantly different at rest and during effort but mean flow under maximum pump speed was higher with HTM II (13 L vs. 10 L, p = 0.02). Left atrial pressure was lower at rest and during effort for the HTM II (11 mm Hg vs. 3 mm Hg, p = 0.02 and 9 mm Hg vs. 2 mm Hg, p = 0.008) than with the VTA, but with greater risk of left-ventricle suck-down for the axial flow. Power consumption for a similar flow was lower with the VTA during rest (4.7 W vs. 6.9 W, p = 0.002) and during effort (4.3 W vs. 6.6 W, p = 0.008). In case of high pulmonary vascular resistance with preserved right ventricular function, lower right ventricular pressure was obtained with HTM II (21 mm Hg vs. 28 mm Hg, p = 0.03). Observed results are in favor of a better discharge of the left and right cavities with the HTM II compared to the VTA yet with a higher risk of left cavity collapse occurrence. PMID:24577368

  11. A Mock Circulatory System to Assess the Performance of Continuous-Flow Left Ventricular Assist Devices (LVADs): Does Axial Flow Unload Better Than Centrifugal LVAD?

    PubMed Central

    2014-01-01

    Hemodynamic performances comparisons between different types of left ventricular assist devices (LVADs) remain difficult in a clinical context. The aim of this study was to create an experimental model to assess and compare two types of LVAD under hemodynamic conditions that simulated physical effort and pulmonary hypertension. An experimental mock circulatory system was created to simulate the systemic and pulmonary circulations and consisted of pulsatile left and right cardiac simulators (cardiowest pump), air/water tanks to model compliances, and tubes to model the venous and arterial resistances. Two types of continuous-flow ventricular assist devices were connected to this pulsated model: an axial flow pump, Heartmate II (HTM II), and a centrifugal pump, VentrAssist (VTA). The hemodynamic conditions at rest and during exercise were replicated. Mean aortic pressures were not significantly different at rest and during effort but mean flow under maximum pump speed was higher with HTM II (13 L vs. 10 L, p = 0.02). Left atrial pressure was lower at rest and during effort for the HTM II (11 mm Hg vs. 3 mm Hg, p = 0.02 and 9 mm Hg vs. 2 mm Hg, p = 0.008) than with the VTA, but with greater risk of left-ventricle suck-down for the axial flow. Power consumption for a similar flow was lower with the VTA during rest (4.7 W vs. 6.9 W, p = 0.002) and during effort (4.3 W vs. 6.6 W, p = 0.008). In case of high pulmonary vascular resistance with preserved right ventricular function, lower right ventricular pressure was obtained with HTM II (21 mm Hg vs. 28 mm Hg, p = 0.03). Observed results are in favor of a better discharge of the left and right cavities with the HTM II compared to the VTA yet with a higher risk of left cavity collapse occurrence. PMID:24577368

  12. 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).

  13. 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.

  14. Multiplexed single-molecule force spectroscopy using a centrifuge

    PubMed Central

    Yang, Darren; Ward, Andrew; Halvorsen, Ken; Wong, Wesley P.

    2016-01-01

    We present a miniature centrifuge force microscope (CFM) that repurposes a benchtop centrifuge for high-throughput single-molecule experiments with high-resolution particle tracking, a large force range, temperature control and simple push-button operation. Incorporating DNA nanoswitches to enable repeated interrogation by force of single molecular pairs, we demonstrate increased throughput, reliability and the ability to characterize population heterogeneity. We perform spatiotemporally multiplexed experiments to collect 1,863 bond rupture statistics from 538 traceable molecular pairs in a single experiment, and show that 2 populations of DNA zippers can be distinguished using per-molecule statistics to reduce noise. PMID:26984516

  15. Multiplexed single-molecule force spectroscopy using a centrifuge

    NASA Astrophysics Data System (ADS)

    Yang, Darren; Ward, Andrew; Halvorsen, Ken; Wong, Wesley P.

    2016-03-01

    We present a miniature centrifuge force microscope (CFM) that repurposes a benchtop centrifuge for high-throughput single-molecule experiments with high-resolution particle tracking, a large force range, temperature control and simple push-button operation. Incorporating DNA nanoswitches to enable repeated interrogation by force of single molecular pairs, we demonstrate increased throughput, reliability and the ability to characterize population heterogeneity. We perform spatiotemporally multiplexed experiments to collect 1,863 bond rupture statistics from 538 traceable molecular pairs in a single experiment, and show that 2 populations of DNA zippers can be distinguished using per-molecule statistics to reduce noise.

  16. Multiplexed single-molecule force spectroscopy using a centrifuge.

    PubMed

    Yang, Darren; Ward, Andrew; Halvorsen, Ken; Wong, Wesley P

    2016-01-01

    We present a miniature centrifuge force microscope (CFM) that repurposes a benchtop centrifuge for high-throughput single-molecule experiments with high-resolution particle tracking, a large force range, temperature control and simple push-button operation. Incorporating DNA nanoswitches to enable repeated interrogation by force of single molecular pairs, we demonstrate increased throughput, reliability and the ability to characterize population heterogeneity. We perform spatiotemporally multiplexed experiments to collect 1,863 bond rupture statistics from 538 traceable molecular pairs in a single experiment, and show that 2 populations of DNA zippers can be distinguished using per-molecule statistics to reduce noise. PMID:26984516

  17. 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.

  18. Application of annular centrifugal contactors in the hot test of the improved total partitioning process for high level liquid waste.

    PubMed

    Duan, Wuhua; Chen, Jing; Wang, Jianchen; Wang, Shuwei; Feng, Xiaogui; Wang, Xinghai; Li, Shaowei; Xu, Chao

    2014-08-15

    High level liquid waste (HLLW) produced from the reprocessing of the spent nuclear fuel still contains moderate amounts of uranium, transuranium (TRU) actinides, (90)Sr, (137)Cs, etc., and thus constitutes a permanent hazard to the environment. The partitioning and transmutation (P&T) strategy has increasingly attracted interest for the safe treatment and disposal of HLLW, in which the partitioning of HLLW is one of the critical technical issues. An improved total partitioning process, including a TRPO (tri-alkylphosphine oxide) process for the removal of actinides, a CESE (crown ether strontium extraction) process for the removal of Sr, and a CECE (calixcrown ether cesium extraction) process for the removal of Cs, has been developed to treat Chinese HLLW. A 160-hour hot test of the improved total partitioning process was carried out using 72-stage 10-mm-dia annular centrifugal contactors (ACCs) and genuine HLLW. The hot test results showed that the average DFs of total α activity, Sr and Cs were 3.57 × 10(3), 2.25 × 10(4) and 1.68 × 10(4) after the hot test reached equilibrium, respectively. During the hot test, 72-stage 10-mm-dia ACCs worked stable, continuously with no stage failing or interruption of the operation. PMID:25016455

  19. Isolation of α-Amylase Inhibitors from Kadsura longipedunculata Using a High-Speed Counter-Current Chromatography Target Guided by Centrifugal Ultrafiltration with LC-MS.

    PubMed

    Cen, Yin; Xiao, Aiping; Chen, Xiaoqing; Liu, Liangliang

    2016-01-01

    In this study, a high-speed counter-current chromatography (HSCCC) separation method target guided by centrifugal ultrafiltration with high-performance liquid chromatography-mass spectrometry (CU-LC-MS) was proposed. This method was used to analyze α-amylase inhibitors from Kadsura longipedunculata extract. According to previous screening with CU-LC-MS, two screened potential α-amylase inhibitors was successfully isolated from Kadsura longipedunculata extract using HSCCC under the optimized experimental conditions. The isolated two target compounds (with purities of 92.3% and 94.6%) were, respectively, identified as quercetin-3-O-rhamnoside (1) and protocatechuic acid (2) based on the MS, UV, and ¹H-NMR spectrometry data. To verify the inhibition of screened compounds, the inhibitory activities of quercetin-3-O-rhamnoside (1) and protocatechuic acid (2) on α-amylase were tested, and it demonstrated that the experimental IC50 values of quercetin-3-O-rhamnoside (1) and protocatechuic acid (2) were 28.8 and 12.5 μmol/L. These results proved that the hyphenated technique using CU-LC-MS and HSCCC was a rapid, competent, and reproductive method to screen and separate potential active compounds, like enzyme inhibitors from the extract of herbal medicines. PMID:27617987

  20. High Voltage TAL Performance

    NASA Technical Reports Server (NTRS)

    Jacobson, David T.; Jankovsky, Robert S.; Rawlin, Vincent K.; Manzella, David H.

    2001-01-01

    The performance of a two-stage, anode layer Hall thruster was evaluated. Experiments were conducted in single and two-stage configurations. In single-stage configuration, the thruster was operated with discharge voltages ranging from 300 to 1700 V. Discharge specific impulses ranged from 1630 to 4140 sec. Thruster investigations were conducted with input power ranging from 1 to 8.7 kW, corresponding to power throttling of nearly 9: 1. An extensive two-stage performance map was generated. Data taken with total voltage (sum of discharge and accelerating voltage) constant revealed a decrease in thruster efficiency as the discharge voltage was increased. Anode specific impulse values were comparable in the single and two-stage configurations showing no strong advantage for two-stage operation.

  1. High Performance Arcjet Engines

    NASA Technical Reports Server (NTRS)

    Kennel, Elliot B.; Ivanov, Alexey Nikolayevich; Nikolayev, Yuri Vyacheslavovich

    1994-01-01

    This effort sought to exploit advanced single crystal tungsten-tantalum alloy material for fabrication of a high strength, high temperature arcjet anode. The use of this material is expected to result in improved strength, temperature resistance, and lifetime compared to state of the art polycrystalline alloys. In addition, the use of high electrical and thermal conductivity carbon-carbon composites was considered, and is believed to be a feasible approach. Highly conductive carbon-carbon composite anode capability represents enabling technology for rotating-arc designs derived from the Russian Scientific Research Institute of Thermal Processes (NIITP) because of high heat fluxes at the anode surface. However, for US designs the anode heat flux is much smaller, and thus the benefits are not as great as in the case of NIITP-derived designs. Still, it does appear that the tensile properties of carbon-carbon can be even better than those of single crystal tungsten alloys, especially when nearly-single-crystal fibers such as vapor grown carbon fiber (VGCF) are used. Composites fabricated from such materials must be coated with a refractory carbide coating in order to ensure compatibility with high temperature hydrogen. Fabrication of tungsten alloy single crystals in the sizes required for fabrication of an arcjet anode has been shown to be feasible. Test data indicate that the material can be expected to be at least the equal of W-Re-HfC polycrystalline alloy in terms of its tensile properties, and possibly superior. We are also informed by our colleagues at Scientific Production Association Luch (NP0 Luch) that it is possible to use Russian technology to fabricate polycrystalline W-Re-HfC or other high strength alloys if desired. This is important because existing engines must rely on previously accumulated stocks of these materials, and a fabrication capability for future requirements is not assured.

  2. Centrifugal reciprocating compressor

    NASA Technical Reports Server (NTRS)

    High, W. H.

    1980-01-01

    Efficient compressor uses centrifugal force to compress gas. System incorporates two coupled dc motors, each driving separate centrifugal reciprocating-compressor assembly. Motors are synchronized to accelerate and decelerate alternately.

  3. Analysis and identification of subsynchronous vibration for a high pressure parallel flow centrifugal compressor

    NASA Technical Reports Server (NTRS)

    Kirk, R. G.; Nicholas, J. C.; Donald, G. H.; Murphy, R. C.

    1980-01-01

    The summary of a complete analytical design evaluation of an existing parallel flow compressor is presented and a field vibration problem that manifested itself as a subsynchronous vibration that tracked at approximately 2/3 of compressor speed is reviewed. The comparison of predicted and observed peak response speeds, frequency spectrum content, and the performance of the bearing-seal systems are presented as the events of the field problem are reviewed. Conclusions and recommendations are made as to the degree of accuracy of the analytical techniques used to evaluate the compressor design.

  4. High performance cyclone development

    SciTech Connect

    Giles, W.B.

    1981-01-01

    The results of cold flow experiments at atmospheric conditions of an air-shielded 18 in-dia electrocyclone with a central cusped electrode are reported using fine test dusts of both flyash and nickel powder. These results are found to confirm expectations of enhanced performance, similar to earlier work on a 12 in-dia model. An analysis of the combined inertial-electrostatic force field is also presented which identifies general design goals and scaling laws. From this, it is found that electrostatic enhancement will be particularly beneficial for fine dusts in large cyclones. Recommendations for further improvement in cyclone collection efficiency are proposed.

  5. START High Performance Discharges

    NASA Astrophysics Data System (ADS)

    Gates, D. A.

    1997-11-01

    Improvements to START (Small Tight Aspect Ratio Tokamak), the first spherical tokamak in the world to achieve high plasma temperature with both a significant pulse length and confinement time, have been ongoing since 1991. Recent modifications include: expansion of the existing capacitor banks allowing plasma currents as high as 300kA, an increase in the available neutral beam heating power ( ~ 500kW), and improvements to the vacuum system. These improvements have led to the achievement of the world record plasma β (≡ 2μ_0 /B^2) of ~ 30% in a tokamak. The normalised β ( βN ≡ β aB/I_p) reached 4.5 with q_95 = 2.3. Properties of the reconstructed equilibrium will be discussed in detail. The theoretical limit to β is higher in a spherical tokamak than in a conventional machine, due to the higher values of normalised current (IN ≡ I_p/aB) achievable at low aspect ratio. The record β was achieved with IN ~ 8 while conventional tokamaks are limited to IN ~ 3, or less. Calculations of the ideal MHD stability of the record discharge indicate high β low-n kink modes are stable, but that the entire profile is at or near marginal stability for high-n ballooning modes. The phenomenology of the events leading up to the plasma termination is discussed. An important aspect of the START program is to explore the physics of neutral beam absorption at low aspect ratio. A passive neutral particle analyser has been used to study the temporal and spatial dependence of the fast hydrogen beam ions. These measurements have been used in conjunction with a single particle orbit code to estimate the fast ion losses due to collisions with slow neutrals from the plasma edge. Numerical analysis of neutral beam power deposition profiles are compared with the data from an instrumented beam stop. The global energy confinement time τE in beam heated discharges on START is similar to that obtained in Ohmic discharges, even though the input power has roughly doubled over the Ohmic case

  6. CENTRIFUGE END CAP

    DOEpatents

    Beams, J.W.; Snoddy, L.B.

    1960-08-01

    An end cap for ultra-gas centrifuges is designed to impart or remove angular momentum to or from the gas and to bring the entering gas to the temperature of the gas inside the centrifuge. The end cap is provided with slots or fins for adjusting the temperature and the angular momentum of the entering gas to the temperature and momentum of the gas in the centrifuge and is constructed to introduce both the inner and the peripheral stream into the centrifuge.

  7. Tough high performance composite matrix

    NASA Technical Reports Server (NTRS)

    Pater, Ruth H. (Inventor); Johnston, Norman J. (Inventor)

    1994-01-01

    This invention is a semi-interpentrating polymer network which includes a high performance thermosetting polyimide having a nadic end group acting as a crosslinking site and a high performance linear thermoplastic polyimide. Provided is an improved high temperature matrix resin which is capable of performing in the 200 to 300 C range. This resin has significantly improved toughness and microcracking resistance, excellent processability, mechanical performance, and moisture and solvent resistances.

  8. A computational study of the effects of inlet guide vanes on the performance of a centrifugal blood pump.

    PubMed

    Chan, W K; Wong, Y W; Yu, S C M; Chua, L P

    2002-06-01

    This article presents computational studies on the effects of inlet guide vanes (IGVs) on the flow pattern and shear stress in a centrifugal blood pump. The effect of IGVs is to introduce a pre-swirl to fluid particles entering the impeller with the intention that the fluid particles will travel along the blade profile. Currently, most commercial centrifugal blood pumps employ straight radial impeller blades that are not hydrodynamically ideal for a good flow pattern within the blade passage. Flow separation and formation of vortices within the blade passage are believed to increase the degree of hemolysis and thrombosis. These are causes for blood clotting that will lead to malfunctioning of ventricular assist devices. Four IGVs of different geometrical profiles have been numerically investigated using a commercial software program CFX-Tascflow. The pump is operated at 2,000 rpm, and the results revealed that the relative flow patterns in the blade passage have been dramatically altered. The size of the vortices was reduced, and the pressure contours indicated a gradual rise from the impeller leading edge to the trailing edge. However, inclusion of IGV causes a drop in the pressure head generated. Higher frictional losses are incurred as fluid particles passed through the IGV. In addition, the IGV modifies the inlet velocity triangles, and this also contributes to a drop in the pressure head generated that is consistent with Euler's pump theory. The change in the flow patterns and the gradual variation of the pressure contours have led to lower shear stress within the blade passages as compared to the case without IGVs. PMID:12072110

  9. Collaborative flowsheet development studies using cobalt dicarbollide and phosphine oxide for the partitioning of radionuclides from Idaho Chemical Processing Plant high-activity liquid waste with centrifugal contactors

    SciTech Connect

    Law, J.D.; Herbst, R.S.; Todd, T.A.

    1996-12-31

    Two solvent extraction technologies under development in Russia for the partitioning of radionuclides from radioactive wastes were tested at the Idaho Chemical Processing Plant (ICPP) with simulated high-activity liquid waste (HAW) on a continuous basis using 24 stages of 2-cm diameter centrifugal contactors. Two flowsheet tests were conducted with chlorinated cobalt dicarbollide (ChCoDiC) to evaluate the separation of cesium and strontium from ICPP HAW. Also, a flowsheet test was performed with a derivative of phosphine oxide (POR) to evaluate the separation of actinides, rare earths, and technetium from ICPP HAW. All experiments utilized a non-radioactive HAW simulant prepared to emulate the macro (or matrix) constituents of actual ICPP HAW at their average tank composition. The behavior of the species of interest was monitored using the stable forms of Sr and Cs, europium as a surrogate for americium, and rhenium as a surrogate for technetium. Removal efficiencies and distribution coefficients were determined for each flowsheet at steady-state conditions. Results of this testing indicate the POR and ChCoDiC processes can be used to effectively treat ICPP HAW. This series of tests is a continuation of ongoing efforts to evaluate the applicability of these Russian developed technologies to U.S. nuclear wastes under the auspices of a joint program between the U.S. Department of Energy and the Russian Ministry of Atomic Energy.

  10. High Voltage SPT Performance

    NASA Technical Reports Server (NTRS)

    Manzella, David; Jacobson, David; Jankovsky, Robert

    2001-01-01

    A 2.3 kW stationary plasma thruster designed to operate at high voltage was tested at discharge voltages between 300 and 1250 V. Discharge specific impulses between 1600 and 3700 sec were demonstrated with thrust between 40 and 145 mN. Test data indicated that discharge voltage can be optimized for maximum discharge efficiency. The optimum discharge voltage was between 500 and 700 V for the various anode mass flow rates considered. The effect of operating voltage on optimal magnet field strength was investigated. The effect of cathode flow rate on thruster efficiency was considered for an 800 V discharge.

  11. High performance steam development

    SciTech Connect

    Duffy, T.; Schneider, P.

    1995-10-01

    Over 30 years ago U.S. industry introduced the world`s highest temperature (1200{degrees}F at 5000 psig) and most efficient power plant, the Eddystone coal-burning steam plant. The highest alloy material used in the plant was 316 stainless steel. Problems during the first few years of operation caused a reduction in operating temperature to 1100{degrees}F which has generally become the highest temperature used in plants around the world. Leadership in high temperature steam has moved to Japan and Europe over the last 30 years.

  12. Rotating and positive-displacement pumps for low-thrust rocket engines. Volume 1: Pump Evaluation and design. [of centrifugal pumps

    NASA Technical Reports Server (NTRS)

    Macgregor, C.; Csomor, A.

    1974-01-01

    Rotating and positive displacement pumps of various types were studied for pumping liquid fluorine for low-thrust, high-performance rocket engines. Included in the analysis were: centrifugal, pitot, Barske, Tesla, drag, gear, vane, axial piston, radial piston, diaphragm, and helirotor pump concepts. The centrifugal pump and the gear pump were selected and these were carried through detailed design and fabrication. Mechanical difficulties were encountered with the gear pump during the preliminary tests in Freon-12. Further testing and development was therefore limited to the centrifugal pump. Tests on the centrifugal pump were conducted in Freon-12 to determine the hydrodynamic performance and in liquid fluorine to demonstrate chemical compatibility.

  13. 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.

  14. Centrifugal inertia effects in two-phase face seal films

    NASA Technical Reports Server (NTRS)

    Basu, P.; Hughes, W. F.; Beeler, R. M.

    1987-01-01

    A simplified, semianalytical model has been developed to analyze the effect of centrifugal inertia in two-phase face seals. The model is based on the assumption of isothermal flow through the seal, but at an elevated temperature, and takes into account heat transfer and boiling. Using this model, seal performance curves are obtained with water as the working fluid. It is shown that the centrifugal inertia of the fluid reduces the load-carrying capacity dramatically at high speeds and that operational instability exists under certain conditions. While an all-liquid seal may be starved at speeds higher than a 'critical' value, leakage always occurs under boiling conditions.

  15. High performance alloy electroforming

    NASA Technical Reports Server (NTRS)

    Malone, G. A.; Winkelman, D. M.

    1989-01-01

    Electroformed copper and nickel are used in structural applications for advanced propellant combustion chambers. An improved process has been developed by Bell Aerospace Textron, Inc. wherein electroformed nickel-manganese alloy has demonstrated superior mechanical and thermal stability when compared to previously reported deposits from known nickel plating processes. Solution chemistry and parametric operating procedures are now established and material property data is established for deposition of thick, large complex shapes such as the Space Shuttle Main Engine. The critical operating variables are those governing the ratio of codeposited nickel and manganese. The deposition uniformity which in turn affects the manganese concentration distribution is affected by solution resistance and geometric effects as well as solution agitation. The manganese concentration in the deposit must be between 2000 and 3000 ppm for optimum physical properties to be realized. The study also includes data regarding deposition procedures for achieving excellent bond strength at an interface with copper, nickel-manganese or INCONEL 718. Applications for this electroformed material include fabrication of complex or re-entry shapes which would be difficult or impossible to form from high strength alloys such as INCONEL 718.

  16. High Poverty, High Performing Schools. IDRA Focus.

    ERIC Educational Resources Information Center

    IDRA Newsletter, 1997

    1997-01-01

    This theme issue includes four articles on high performance by poor Texas schools. In "Principal of National Blue Ribbon School Says High Poverty Schools Can Excel" (interview with Robert Zarate by Christie L. Goodman), the principal of Mary Hull Elementary School (San Antonio, Texas) describes how the high-poverty, high-minority school…

  17. Rhie-Chow interpolation in strong centrifugal fields

    NASA Astrophysics Data System (ADS)

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

    2015-10-01

    Rhie-Chow interpolation formulas are derived from the Navier-Stokes and continuity equations. These formulas are generalized to gas dynamics in strong centrifugal fields (as high as 106 g) occurring in gas centrifuges.

  18. 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

  19. High Performance Fortran: An overview

    SciTech Connect

    Zosel, M.E.

    1992-12-23

    The purpose of this paper is to give an overview of the work of the High Performance Fortran Forum (HPFF). This group of industry, academic, and user representatives has been meeting to define a set of extensions for Fortran dedicated to the special problems posed by a very high performance computers, especially the new generation of parallel computers. The paper describes the HPFF effort and its goals and gives a brief description of the functionality of High Performance Fortran (HPF).

  20. Design Method for Single-Blade Centrifugal Pump Impeller

    NASA Astrophysics Data System (ADS)

    Nishi, Yasuyuki; Fujiwara, Ryota; Fukutomi, Junichiro

    The sewage pumps are demanded a high pump efficiency and a performance in passing foreign bodies. Therefore, the impeller used by these usages requires the large passed particle size (minimum particle size in the pump). However, because conventional design method of pump impeller results in small impeller exit width, it is difficult to be applied to the design of single-blade centrifugal pump impeller which is used as a sewage pump. This paper proposes a design method for single-blade centrifugal pump impeller. As a result, the head curve of the impeller designed by the proposed design method satisfied design specifications, and pump efficiency was over 62% more than conventional single-blade centrifugal pump impeller. By comparing design values with CFD analysis values, the suction velocity ratio of the design parameter agreed well with each other, but the relative velocity ratio did not agree due to the influence of the backflow of the impeller entrance.

  1. 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.

  2. Recent ORNL experience in site performance prediction: the Gas Centrifuge Enrichment Plant and the Oak Ridge Central Waste Disposal Facility

    SciTech Connect

    Pin, F.G.

    1985-01-01

    The suitability of the Portsmouth Gas Centrifuge Enrichment Plant Landfill and the Oak Ridge, Tennessee, Central Waste Disposal Facility for disposal of low-level radioactive waste was evaluated using pathways analyses. For these evaluations, a conservative approach was selected; that is, conservatism was built into the analyses when assumptions concerning future events had to be made or when uncertainties concerning site or waste characteristics existed. Data from comprehensive laboratory and field investigations were used in developing the conceptual and numerical models that served as the basis for the numerical simulations of the long-term transport of contamination to man. However, the analyses relied on conservative scenarios to describe the generation and migration of contamination and the potential human exposure to the waste. Maximum potential doses to man were calculated and compared to the appropriate standards. Even under this conservative framework, the sites were found to provide adequate buffer to persons outside the DOE reservations and conclusions concerning site capacity and site acceptability were drawn. Our experience through these studies has shown that in reaching conclusions in such studies, some consideration must be given to the uncertainties and conservatisms involved in the analyses. Analytical methods to quantitatively assess the probability of future events to occur and to quantitatively determine the sensitivity of the results to data uncertainty may prove useful in relaxing some of the conservatism built into the analyses. The applicability of such methods to pathways analyses is briefly discussed.

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

    NASA Astrophysics Data System (ADS)

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

    2004-08-01

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

  4. Effect of area ratio on the performance of a 5.5:1 pressure ratio centrifugal impeller

    NASA Technical Reports Server (NTRS)

    Schumann, L. F.; Clark, D. A.; Wood, J. R.

    1986-01-01

    A centrifugal impeller which was initially designed for a pressure ratio of approximately 5.5 and a mass flow rate of 0.959 kg/sec was tested with a vaneless diffuser for a range of design point impeller area ratios from 2.322 to 2.945. The impeller area ratio was changed by successively cutting back the impeller exit axial width from an initial value of 7.57 mm to a final value of 5.97 mm. In all, four separate area ratios were tested. For each area ratio a series of impeller exit axial clearances was also tested. Test results are based on impeller exit surveys of total pressure, total temperature, and flow angle at a radius 1.115 times the impeller exit radius. Results of the tests at design speed, peak efficiency, and an exit tip clearance of 8 percent of exit blade height show that the impeller equivalent pressure recovery coefficient peaked at a design point area ratio of approximately 2.748 while the impeller aerodynamic efficiency peaked at a lower value of area ratio of approximately 2.55. The variation of impeller efficiency with clearance showed expected trends with a loss of approximately 0.4 points in impeller efficiency for each percent increase in exit axial tip clearance for all impellers tested.

  5. 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

  6. High Performance Thin Layer Chromatography.

    ERIC Educational Resources Information Center

    Costanzo, Samuel J.

    1984-01-01

    Clarifies where in the scheme of modern chromatography high performance thin layer chromatography (TLC) fits and why in some situations it is a viable alternative to gas and high performance liquid chromatography. New TLC plates, sample applications, plate development, and instrumental techniques are considered. (JN)

  7. 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

  8. 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.

  9. Laser and gas centrifuge enrichment

    NASA Astrophysics Data System (ADS)

    Heinonen, Olli

    2014-05-01

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

  10. High Performance Networks for High Impact Science

    SciTech Connect

    Scott, Mary A.; Bair, Raymond A.

    2003-02-13

    This workshop was the first major activity in developing a strategic plan for high-performance networking in the Office of Science. Held August 13 through 15, 2002, it brought together a selection of end users, especially representing the emerging, high-visibility initiatives, and network visionaries to identify opportunities and begin defining the path forward.

  11. Assessment of Hydraulic Performance and Biocompatibility of a MagLev Centrifugal Pump System Designed for Pediatric Cardiac or Cardiopulmonary Support

    PubMed Central

    Dasse, Kurt A.; Gellman, Barry; Kameneva, Marina V.; Woolley, Joshua R.; Johnson, Carl A.; Gempp, Thomas; Marks, John D.; Kent, Stella; Koert, Andrew; Richardson, J. Scott; Franklin, Steve; Snyder, Trevor A.; Wearden, Peter; Wagner, William R.; Gilbert, Richard J.; Borovetz, Harvey S.

    2011-01-01

    The treatment of children with life-threatening cardiac and cardiopulmonary failure is a large and underappreciated public health concern. We have previously shown that the CentriMag is a magnetically levitated centrifugal pump system, having the utility for treating adults and large children (1,500 utilized worldwide). We present here the Pedi-VAS, a pump system whose design was modified from the CentriMag to meet the physiological requirements of young pediatric and neonatal patients. The PediVAS is comprised of a single-use centrifugal blood pump, reusable motor, and console, and is suitable for right ventricular assist device (RVAD), left ventricular assist device (LVAD), biventricular assist device (BVAD), or extracorporeal membrane oxygenator (ECMO) applications. It is designed to operate without bearings, seals and valves, and without regions of blood stasis, friction, or wear. The PediVAS pump is compatible with the CentriMag hardware, although the priming volume was reduced from 31 to 14 ml, and the port size reduced from 3/8 to ¼ in. For the expected range of pediatric flow (0.3–3.0 L/min), the PediVAS exhibited superior hydraulic efficiency compared with the CentriMag. The PediVAS was evaluated in 14 pediatric animals for up to 30 days, demonstrating acceptable hydraulic function and hemocompatibility. The current results substantiate the performance and biocompatibility of the PediVAS cardiac assist system and are likely to support initiation of a US clinical trial in the future. PMID:18043164

  12. Assessment of hydraulic performance and biocompatibility of a MagLev centrifugal pump system designed for pediatric cardiac or cardiopulmonary support.

    PubMed

    Dasse, Kurt A; Gellman, Barry; Kameneva, Marina V; Woolley, Joshua R; Johnson, Carl A; Gempp, Thomas; Marks, John D; Kent, Stella; Koert, Andrew; Richardson, J Scott; Franklin, Steve; Snyder, Trevor A; Wearden, Peter; Wagner, William R; Gilbert, Richard J; Borovetz, Harvey S

    2007-01-01

    The treatment of children with life-threatening cardiac and cardiopulmonary failure is a large and underappreciated public health concern. We have previously shown that the CentriMag is a magnetically levitated centrifugal pump system, having the utility for treating adults and large children (1,500 utilized worldwide). We present here the PediVAS, a pump system whose design was modified from the CentriMag to meet the physiological requirements of young pediatric and neonatal patients. The PediVAS is comprised of a single-use centrifugal blood pump, reusable motor, and console, and is suitable for right ventricular assist device (RVAD), left ventricular assist device (LVAD), biventricular assist device (BVAD), or extracorporeal membrane oxygenator (ECMO) applications. It is designed to operate without bearings, seals and valves, and without regions of blood stasis, friction, or wear. The PediVAS pump is compatible with the CentriMag hardware, although the priming volume was reduced from 31 to 14 ml, and the port size reduced from 3/8 to (1/4) in. For the expected range of pediatric flow (0.3-3.0 L/min), the PediVAS exhibited superior hydraulic efficiency compared with the CentriMag. The PediVAS was evaluated in 14 pediatric animals for up to 30 days, demonstrating acceptable hydraulic function and hemocompatibility. The current results substantiate the performance and biocompatibility of the PediVAS cardiac assist system and are likely to support initiation of a US clinical trial in the future. PMID:18043164

  13. Different Ways to On-Line Hyphenate Centrifugal Partition Chromatography and Mass Spectrometry: Application to Prenylated Xanthones from Garcinia mangostana.

    PubMed

    Destandau, Emilie; Michel, Thomas; Toribio, Alix; Elfakir, Claire

    2015-11-01

    Centrifugal partition chromatography is a liquid-liquid separation method well adapted for the fractionation or purification of natural compounds from plant extracts. However, following the preparative isolation, the fractions collected must be analysed by high-performance thin-layer chromatography or high-performance liquid chromatography to evaluate their composition and/or their purity. These additional steps are time-consuming and increase the risk of compound degradation. In order to get an instantaneous analysis of fraction content with structural information on the phytochemicals eluted, it is possible to hyphenate on-line centrifugal partition chromatography with mass spectrometry. Depending on the complexity of the extract, two different kinds of centrifugal partition chromatography-mass spectrometry coupling can be performed: centrifugal partition chromatography-mass spectrometry or centrifugal partition chromatography-high-performance liquid chromatography-mass spectrometry coupling. In the first case, one part of the centrifugal partition chromatography effluent is directly introduced in the mass spectrometry ionisation source to identify the eluted compounds, while in the second case, it is directed to a high-performance liquid chromatography-mass spectrometry system where compounds are first separated thanks to high-performance liquid chromatography and then identified using mass spectrometry. PMID:25615274

  14. Vacuum chamber-free centrifuge with magnetic bearings

    NASA Astrophysics Data System (ADS)

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

    2013-09-01

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

  15. Centrifuge rotor integrated analysis

    NASA Astrophysics Data System (ADS)

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

    2004-09-01

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

  16. MOCVD Growth of High-Quality and Density-Tunable GaAs Nanowires on ITO Catalyzed by Au Nanoparticles Deposited by Centrifugation.

    PubMed

    Wu, Dan; Tang, Xiaohong; Yoon, Ho Sup; Wang, Kai; Olivier, Aurelien; Li, Xianqiang

    2015-12-01

    High-quality and density-tunable GaAs nanowires (NWs) are directly grown on indium tin oxide (ITO) using Au nanoparticles (NPs) as catalysts by metal organic chemical vapor deposition (MOCVD). Au catalysts were deposited on ITO glass substrate using a centrifugal method. Compared with the droplet-only method, high-area density Au NPs were uniformly distributed on ITO. Tunable area density was realized through variation of the centrifugation time, and the highest area densities were obtained as high as 490 and 120 NP/μm(2) for 10- and 20-nm diameters of Au NPs, respectively. Based on the vapor-liquid-solid growth mechanism, the growth rates of GaAs NWs at 430 °C were 18.2 and 21.5 nm/s for the highest area density obtained of 10- and 20-nm Au NP-catalyzed NWs. The growth rate of the GaAs NWs was reduced with the increase of the NW density due to the competition of precursor materials. High crystal quality of the NWs was also obtained with no observable planar defects. 10-nm Au NP-induced NWs exhibit wurtzite structure whereas zinc-blende is observed for 20-nm NW samples. Controllable density and high crystal quality of the GaAs NWs on ITO demonstrate their potential application in hybrid a solar cell. PMID:26487507

  17. High performance flexible heat pipes

    NASA Technical Reports Server (NTRS)

    Shaubach, R. M.; Gernert, N. J.

    1985-01-01

    A Phase I SBIR NASA program for developing and demonstrating high-performance flexible heat pipes for use in the thermal management of spacecraft is examined. The program combines several technologies such as flexible screen arteries and high-performance circumferential distribution wicks within an envelope which is flexible in the adiabatic heat transport zone. The first six months of work during which the Phase I contract goal were met, are described. Consideration is given to the heat-pipe performance requirements. A preliminary evaluation shows that the power requirement for Phase II of the program is 30.5 kilowatt meters at an operating temperature from 0 to 100 C.

  18. 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.

  19. Studies on estimating the performance of impellers with cut-down of the blade edge of the centrifugal pump by the surface singularity method

    NASA Astrophysics Data System (ADS)

    Furukawa, Akinori; Cheng, Ci-Chang; Takamatsu, Yasuo

    1990-08-01

    Pump performance depends on the outlet flow of the impeller. A method of surface singularities for core flow in the centrifugal impeller, combined with an integral method for a boundary layer, would explain the mechanism of the performance change caused by cutting the outlet edge of the impeller blades down. This method is applied to flows in the impellers with various cut-downs of the blade edge, and then the calculated results are compared with the experimental ones. Both results are shown to be quantitatively in good agreement. On the influence of cutting the blade edge on the outlet flow, it is indicated that the cut of the pressure surface results in the decrease of relative flow angle with the decrease of radial velocity in the core flow, while that of the suction surface results only in a decrease in radial velocity. The change in the flow separation region due to the cut on the suction surface, however, contributes to the deterioration of pump performance.

  20. High performance dielectric materials development

    NASA Technical Reports Server (NTRS)

    Piche, Joe; Kirchner, Ted; Jayaraj, K.

    1994-01-01

    The mission of polymer composites materials technology is to develop materials and processing technology to meet DoD and commercial needs. The following are outlined in this presentation: high performance capacitors, high temperature aerospace insulation, rationale for choosing Foster-Miller (the reporting industry), the approach to the development and evaluation of high temperature insulation materials, and the requirements/evaluation parameters. Supporting tables and diagrams are included.

  1. Interrogation of fibre Bragg gratings through a fibre optic rotary joint on a geotechnical centrifuge

    NASA Astrophysics Data System (ADS)

    Correia, Ricardo; James, Stephen W.; Marshall, Alec; Heron, Charles; Korposh, Sergiy

    2016-05-01

    The monitoring of an array of fibre Bragg gratings (FBGs) strain sensors was performed through a single channel, single mode fibre optic rotary joint (FORJ) mounted on a geotechnical centrifuge. The array of three FBGs was attached to an aluminum plate that was anchored at the ends and placed on the model platform of the centrifuge. Acceleration forces of up to 50g were applied and the reflection signal of the monitored FBGs recorded dynamically using a 2.5kHz FBG interrogator placed outside the centrifuge. The use of a FORJ allowed the monitoring of the FBGs without submitting the FBG interrogator to the high g-forces experienced in the centrifuge.

  2. METHOD OF CENTRIFUGE OPERATION

    DOEpatents

    Cohen, K.

    1960-05-10

    A method of isotope separation is described in which two streams are flowed axially of, and countercurrently through, a cylindrical centrifuge bowl. Under the influence of a centrifugal field, the light fraction is concentrated in a stream flowing through the central portion of the bowl, whereas the heavy fraction is concentrated in a stream at the periphery thereof.

  3. 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.

  4. 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.

  5. Concept designs of nonrotating-type centrifugal blood pump and basic study on output characteristics of the oscillating disk-type centrifugal pump.

    PubMed

    Kabei, N; Tuichiya, K; Sakurai, Y

    1994-09-01

    When designing a turbo-type blood pump as an artificial heart, the gap between a rotating shaft and a pump housing should be perfectly sealed to prevent any leakage or contamination through a seal. In addition, blood coagulation in a blood chamber must be avoided. To overcome these problems, we proposed five different nonrotating-type turbo pumps: a caudal-fin-type axial-flow pump, a caudal-fin-type centrifugal pump, a nutating-column-type centrifugal pump, a nutating-collapsible-tube-type centrifugal pump, and an oscillating-disk-type centrifugal pump. We selected and developed the oscillating-disk-type centrifugal pump that consists of a disk, a driving rod, a seal, an oscillation mechanism, and a pump housing. The disk is mounted on the end of the rod, which is connected to a high-speed DC motor through an oscillation mechanism. The rod and the disk do not rotate, but they oscillate in the pump housing. This movement of the disk generates forward fluid flow around the axis (i.e., the rotational fluid flow). Centrifugal force due to fluid rotation supports the pressure difference between the outlet and the inlet. The diameter of the disk is 39 mm, the maximum inner diameter of the pump housing is 40 mm, and the volume of the blood chamber for 25 degrees' oscillation is 16.9 ml. The performance of the pump was tested in a mock circulatory system.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:7998882

  6. INL High Performance Building Strategy

    SciTech Connect

    Jennifer D. Morton

    2010-02-01

    High performance buildings, also known as sustainable buildings and green buildings, are resource efficient structures that minimize the impact on the environment by using less energy and water, reduce solid waste and pollutants, and limit the depletion of natural resources while also providing a thermally and visually comfortable working environment that increases productivity for building occupants. As Idaho National Laboratory (INL) becomes the nation’s premier nuclear energy research laboratory, the physical infrastructure will be established to help accomplish this mission. This infrastructure, particularly the buildings, should incorporate high performance sustainable design features in order to be environmentally responsible and reflect an image of progressiveness and innovation to the public and prospective employees. Additionally, INL is a large consumer of energy that contributes to both carbon emissions and resource inefficiency. In the current climate of rising energy prices and political pressure for carbon reduction, this guide will help new construction project teams to design facilities that are sustainable and reduce energy costs, thereby reducing carbon emissions. With these concerns in mind, the recommendations described in the INL High Performance Building Strategy (previously called the INL Green Building Strategy) are intended to form the INL foundation for high performance building standards. This revised strategy incorporates the latest federal and DOE orders (Executive Order [EO] 13514, “Federal Leadership in Environmental, Energy, and Economic Performance” [2009], EO 13423, “Strengthening Federal Environmental, Energy, and Transportation Management” [2007], and DOE Order 430.2B, “Departmental Energy, Renewable Energy, and Transportation Management” [2008]), the latest guidelines, trends, and observations in high performance building construction, and the latest changes to the Leadership in Energy and Environmental Design

  7. High Performance Photovoltaic Project Overview

    SciTech Connect

    Symko-Davies, M.; McConnell, R.

    2005-01-01

    The High-Performance Photovoltaic (HiPerf PV) Project was initiated by the U.S. Department of Energy to substantially increase the viability of photovoltaics (PV) for cost-competitive applications so that PV can contribute significantly to our energy supply and environment in the 21st century. To accomplish this, the National Center for Photovoltaics (NCPV) directs in-house and subcontracted research in high-performance polycrystalline thin-film and multijunction concentrator devices. In this paper, we describe the recent research accomplishments in the in-house directed efforts and the research efforts under way in the subcontracted area.

  8. High-Performance Thermoelectric Semiconductors

    NASA Technical Reports Server (NTRS)

    Fleurial, Jean-Pierre; Caillat, Thierry; Borshchevsky, Alexander

    1994-01-01

    Figures of merit almost double current state-of-art thermoelectric materials. IrSb3 is semiconductor found to exhibit exceptional thermoelectric properties. CoSb3 and RhSb3 have same skutterudite crystallographic structure as IrSb3, and exhibit exceptional transport properties expected to contribute to high thermoelectric performance. These three compounds form solid solutions. Combination of properties offers potential for development of new high-performance thermoelectric materials for more efficient thermoelectric power generators, coolers, and detectors.

  9. High-performance membrane chromatography.

    PubMed

    Belenkii, B G; Malt'sev, V G

    1995-02-01

    In gradient chromatography for proteins migrating along the chromatographic column, the critical distance X0 has been shown to exist at which the separation of zones is at a maximum and band spreading is at a minimum. With steep gradients and small elution velocity, the column length may be reduced to the level of membrane thickness--about one millimeter. The peculiarities of this novel separation method for proteins, high-performance membrane chromatography (HPMC), are discussed and stepwise elution is shown to be especially effective. HPMC combines the advantages of membrane technology and high-performance liquid chromatography, and avoids their drawbacks. PMID:7727132

  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.