WorldWideScience

Sample records for pump flow conditions

  1. Optimal design of multi-conditions for axial flow pump

    Science.gov (United States)

    Shi, L. J.; Tang, F. P.; Liu, C.; Xie, R. S.; Zhang, W. P.

    2016-11-01

    Passage components of the pump device will have a negative flow state when axial pump run off the design condition. Combined with model tests of axial flow pump, this paper use numerical simulation and numerical optimization techniques, and change geometric design parameters of the impeller to optimal design of multi conditions for Axial Flow Pump, in order to improve the efficiency of non-design conditions, broad the high efficient district and reduce operating cost. The results show that, efficiency curve of optimized significantly wider than the initial one without optimization. The efficiency of low flow working point increased by about 2.6%, the designed working point increased by about 0.5%, and the high flow working point increased the most, about 7.4%. The change range of head is small, so all working point can meet the operational requirements. That will greatly reduce operating costs and shorten the period of optimal design. This paper adopted the CFD simulation as the subject analysis, combined with experiment study, instead of artificial way of optimization design with experience, which proves the reliability and efficiency of the optimization design of multi-operation conditions of axial-flow pump device.

  2. Unsteady Flow Analysis of Pump Mode Small Discharge Condition for a Francis Pump-turbine

    Science.gov (United States)

    Xiaoran, ZHAO; Yexiang, XIAO; Jincai, XU; Wei, XU; Jianbo, SUN; Zhengwei, WANG; Yangyang, YAO

    2016-11-01

    Unsteady flow phenomena, including vortex flow at runner inlet, helical backflow in the draft tube and numerous vortexes inside the guide vanes, can occur in pump-turbines under off design conditions at pump mode and can impact normal operation of pump-turbines. All of these phenomena cause serious pressure pulsation, which is quite different from cases in normal pump mode. There is also a difference of pressure pulsation frequency and amplitude in different place through the runner. This paper builds a whole flow passage of a model pump-turbine, simulates flow characteristics in runner by CFD technology, analyses pressure pulsation in the runner and explores the origin and mechanism of pressure pulsations. The SST-CC turbulence model is adopted to perform unsteady simulations of the pump-turbine under 0.46Q BEP small discharge condition at pump mode. Unsteady flow structures are proceeded combined with hydraulic loss and pressure amplitude spectra. The results indicates that there is complicated disordered flow inside the runner under 0.46Q BEP small discharge condition at pump mode, shows the amplitude and frequency characteristic of pressure pulsations through runner flow passage.

  3. Differences in displayed pump flow compared to measured flow under varying conditions during simulated cardiopulmonary bypass.

    LENUS (Irish Health Repository)

    Hargrove, M

    2008-07-01

    Errors in blood flow delivery due to shunting have been reported to reduce flow by, potentially, up to 40-83% during cardiopulmonary bypass. The standard roller-pump measures revolutions per minute and a calibration factor for different tubing sizes calculates and displays flow accordingly. We compared displayed roller-pump flow with ultrasonically measured flow to ascertain if measured flow correlated with the heart-lung pump flow reading. Comparison of flows was measured under varying conditions of pump run duration, temperature, viscosity, varying arterial\\/venous loops, occlusiveness, outlet pressure, use of silicone or polyvinyl chloride (PVC) in the roller race, different tubing diameters, and use of a venous vacuum-drainage device.

  4. Fluid dynamic characterization of operating conditions for continuous flow blood pumps.

    Science.gov (United States)

    Wu, Z J; Antaki, J F; Burgreen, G W; Butler, K C; Thomas, D C; Griffith, B P

    1999-01-01

    As continuous flow pumps become more prominent as long-term ventricular assist devices, the wide range of conditions under which they must be operated has become evident. Designed to operate at a single, best-efficiency, operating point, continuous flow pumps are required to perform at off-design conditions quite frequently. The present study investigated the internal fluid dynamics within two representative rotary fluid pumps to characterize the quality of the flow field over a full range of operating conditions. A Nimbus/UoP axial flow blood pump and a small centrifugal pump were used as the study models. Full field visualization of flow features in the two pumps was conducted using a laser based fluorescent particle imaging technique. Experiments were performed under steady flow conditions. Flow patterns at inlet and outlet sections were visualized over a series of operating points. Flow features specific to each pump design were observed to exist under all operating conditions. At off-design conditions, an annular region of reverse flow was commonly observed within the inlet of the axial pump, while a small annulus of backflow in the inlet duct and a strong disturbed flow at the outlet tongue were observed for the centrifugal pump. These observations were correlated to a critical nondimensional flow coefficient. The creation of a "map" of flow behavior provides an additional, important criterion for determining favorable operating speed for rotary blood pumps. Many unfavorable flow features may be avoided by maintaining the flow coefficient above a characteristic critical coefficient for a particular pump, whereas the intrinsic deleterious flow features can only be minimized by design improvement. Broadening the operating range by raising the band between the critical flow coefficient and the designed flow coefficient, is also a worthy goal for design improvement.

  5. The performance of a cryogenic pump for the two-phase flow condition

    OpenAIRE

    YAMADA, HITOSHI; WATANABE, Mitsuo; Hasegawa, Satoshi; Kamijo, Kenjiro; 山田, 仁; 渡辺, 光男; 長谷川, 敏; 上條, 謙二郎

    1985-01-01

    An experimental investigation was carried out in order to obtain the performance characteristics of a cryogenic pump under a two-phase flow condition. The experiment used an oxygen pump with an inducer and liquid nitrogen as the test fluid. The vapor volumetric fraction at the pump inlet was calculated with an assumption of a constant enthalpy process across an orifice which was used to generate the two-phase flow at the pump inlet. The results showed that the pump head rise did hardly decrea...

  6. Study on Performance and Internal Flow Condition of Mini Turbo-Pump

    Science.gov (United States)

    Shigemitsu, Toru; Fukutomi, Junichiro; Nasada, Ryoichi

    2010-06-01

    Mini turbo-pumps which have a diameter smaller than 100mm are utilized in many fields; automobile radiator pump, artificial heart pump, cooling pump for electric devices, washing machine pump and so on. And the needs for the mini turbo-pumps would become larger with the increase of the application of it for electrical machines. It is desirable that the mini turbo-pump design is as simple as possible due to the limitation of the precision for manufacture. But the design method for the mini turbo-pump is not established because the internal flow condition for these small-sized fluid machineries is not clarified and conventional theory is not conductive for small-sized pumps because of the low Reynolds number and the size effects. Therefore, we started the research of the mini turbo-pump for the purpose of development of high performance mini turbo-pump with simple structure. As a first step of this research, mini turbo-pump with the 46mm rotor diameter was designed based on the conventional design method in order to clarify the problems for the application of conventional method for mini turbo-pump in details. The three dimensional steady numerical flow analysis was conducted with the commercial code (Fluent6.3). The numerical flow analysis was also performed under the condition with and without a tip clearance because the tip clearance influence on the performance and internal flow condition is extremely large for mini turbo-pumps. It was clarified from the numerical results that head of the mini turbo-pump at the designed point without the tip clearance satisfied the designed value head H = 1.2m and the efficiency is about η = 60% which is acceptable value for the centrifugal pump. On the other hand, head and efficiency decreased drastically with the increase of the tip clearance. The flow condition near the tip region was influenced by the leakage flow from the blade tip. And it is observed by the results of the total pressure distributions that the total

  7. Numerical Flow Simulation in a Centrifugal Pump at Design and Off-Design Conditions

    Directory of Open Access Journals (Sweden)

    K. W. Cheah

    2007-01-01

    Full Text Available The current investigation is aimed to simulate the complex internal flow in a centrifugal pump impeller with six twisted blades by using a three-dimensional Navier-Stokes code with a standard k-ε two-equation turbulence model. Different flow rates were specified at inlet boundary to predict the characteristics of the pump. A detailed analysis of the results at design load, Qdesign, and off-design conditions, Q = 0.43 Qdesign and Q = 1.45 Qdesign, is presented. From the numerical simulation, it shows that the impeller passage flow at design point is quite smooth and follows the curvature of the blade. However, flow separation is observed at the leading edge due to nontangential inflow condition. The flow pattern changed significantly inside the volute as well, with double vortical flow structures formed at cutwater and slowly evolved into a single vortical structure at the volute diffuser. For the pressure distribution, the pressure increases gradually along streamwise direction in the impeller passages. When the centrifugal pump is operating under off-design flow rate condition, unsteady flow developed in the impeller passage and the volute casing.

  8. The effect of blade outlet angle on performance and internal flow condition of mini turbo-pump

    Science.gov (United States)

    Shigemitsu, T.; Fukutomi, J.; Nasada, R.; Kaji, K.

    2011-03-01

    Mini turbo-pumps having a diameter smaller than 100mm are employed in many fields; automobile radiator pump, ventricular assist pump, cooling pump for electric devices, washing machine pump and so on. Further, the needs for mini turbo-pumps would become larger with the increase of the application of it for electrical machines. It is desirable that the mini turbo-pump design is as simple as possible due to restriction to make precise manufactures. But the design method for the mini turbo-pump is not established because the internal flow condition for these small-sized fluid machineries is not clarified and conventional theory is not conductive for small-sized pumps. Three types of rotors with different outlet angles are prepared for an experiment and a numerical analysis. The performance tests are conducted with these rotors in order to investigate the effect of the blade outlet angle on performance and internal flow condition of mini turbo-pumps. It is clarified from the experimental results that head of the mini turbo-pump increases and maximum efficiency flow rate shifts to larger flow rate according to the increase of the blade outlet angle, however the maximum efficiency decreases with the increase of it. In the present paper, the performance of the mini turbo-pump is shown and the internal flow conditions are clarified with the results of the experiment and the numerical flow analysis. Furthermore, the effects of the blade outlet angle on the performance are investigated and high performance design with simple structure for the mini turbo-pump would be considered.

  9. High-speed flow visualization in a pump-turbine under off-design operating conditions

    Energy Technology Data Exchange (ETDEWEB)

    Hasmatuchi, V; Roth, S; Botero, F; Avellan, F; Farhat, M, E-mail: vlad.hasmatuchi@epfl.c [Laboratory for Hydraulic Machines, Ecole Polytechnique Federale de Lausanne Av. de Cour 33bis, Lausanne, CH-1007 (Switzerland)

    2010-08-15

    The flow hydrodynamics in a low specific speed radial pump-turbine reduced scale model is experimentally investigated under off-design operating conditions in generating mode. Wall pressure measurements, in the stator, synchronized with high-speed flow visualizations in the vaneless space between the impeller and the guide vanes using air bubbles injection are performed. When starting from the best efficiency point and increasing the runner speed, a significant increase of the pressure fluctuations is observed mainly in channels between wicket gates. The spectral analysis shows a rise of one stall cell, rotating with about 70% of the impeller frequency, at runaway, which further increases as the zero discharge condition is approached. Then a specific image processing technique is detailed and applied to create a synthetic instantaneous view of the flow pattern on the entire guide vanes circumference for an operating point in turbine-brake mode, where backflow and vortices accompany the stall passage.

  10. Numerical analysis of head degrade law under cavitation condition of contra-rotating axial flow waterjet pump

    Science.gov (United States)

    Huang, D.; Pan, Z. Y.

    2015-01-01

    In order to study the flow-head characteristic curve, the SST turbulence model, homogeneous multiphase model and Rayleigh-Plesset equation were applied to simulate the cavitation characteristics in contra-rotating axial flow waterjet pump under different conditions based on ANSYS CFX software. The distribution of cavity, pressure coefficient of the blade at the design point under different cavitation conditions were obtained. The analysis results of flow field show that the vapour volume distribution on the impeller indicates that the vapour first appears at the leading edge of blade and then extends to the outlet of impeller with the reduction of Net Positive Suction Head Allowance (NPSHA). The present study illustrates that the main reason for the decline of the pump performance is the development of cavitation, and the simulation can truly reflect the cavitation performance of the contra-rotating axial flow waterjet pump.

  11. Flow patterns and boundary conditions for inlet and outlet conduits of large pump system with low head

    Institute of Scientific and Technical Information of China (English)

    徐磊; 陆伟刚; 陆林广; 董雷; 王兆飞

    2014-01-01

    The flow patterns in the inlet and outlet conduits have a decisive effect on the safe, stable, and highly efficient operation of the pump in a large pumping station with low head. The numerical simulation of three-dimensional (3D) turbulence flow in conduits is an important method to study the hydraulic performance and conduct an optimum hydraulic design for the conduits. With the analyses of the flow patterns in the inlet and outlet conduits, the boundary conditions of the numerical simulation for them can be determined. The main obtained conclusions are as follows: (i) Under normal operation conditions, there is essentially no pre-swirl flow at the impeller chamber inlet of an axial-flow pump system, based on which the boundary condition at the inlet conduit may be defined. (ii) The circulation at the guide vane outlet of an axial-flow pump system has a great effect on the hydraulic performance of the outlet conduit, and there is optimum circulation for the performance. Therefore, it is strongly suggested to design the guide vane according to the optimum circulation. (iii) The residual circulation at the guide vane outlet needs to be considered for the inlet boundary condition of the outlet conduit, and the value of the circulation may be measured in a specially designed test model.

  12. Numerical prediction of 3-D periodic flow unsteadiness in a centrifugal pump under part-load condition

    Institute of Scientific and Technical Information of China (English)

    裴吉; 袁寿其; 李晓俊; 袁建平

    2014-01-01

    Numerical simulation and 3-D periodic flow unsteadiness analysis for a centrifugal pump with volute are carried out in whole flow passage, including the impeller with twisted blades, the volute and the side chamber channels under a part-load condition. The pressure fluctuation intensity coefficient (PFIC) based on the standard deviation method, the time-averaged velocity unsteadi-ness intensity coefficient (VUIC) and the time-averaged turbulence intensity coefficient (TIC) are defined by averaging the results at each grid node for an entire impeller revolution period. Therefore, the strength distributions of the periodic flow unsteadiness based on the unsteady Reynolds-averaged Navier-Stokes (URANS) equations can be analyzed directly and in detail. It is shown that under the des.0.6Q condition, the pressure fluctuation intensity is larger near the blade pressure side than near the suction side, and a high fluctuation intensity can be observed at the beginning section of the spiral of the volute. The flow velocity unsteadiness intensity is larger near the blade suction side than near the pressure side. A strong turbulence intensity can be found near the blade suction side, the impeller shroud side as well as in the side chamber. The leakage flow has a significant effect on the inflow of the impeller, and can increase both the flow velocity unsteadiness intensity and the turbulence intensity near the wall. The accumulative flow unstea-diness results of an impeller revolution can be an important aspect to be considered in the centrifugal pump optimum design for ob-taining a more stable inner flow of the pump and reducing the flow-induced vibration and noise in certain components.

  13. Operating pumps on minimum flow

    Energy Technology Data Exchange (ETDEWEB)

    Casada, D.A. [Oak Ridge National Lab., TN (United States); Li, Y.C. [Nuclear Regulatory Commission, Washington, DC (United States)

    1992-06-01

    The Nuclear Regulatory Commission (NRC) staff issued Information Notice (IN) 87-59 to alert all licensees to two miniflow design concerns identified by Westinghouse. The first potential problem discussed in this IN involves parallel pump operation. If the head/capacity curve of one of the parallel pumps is greater than the other, the weaker pump may be dead-headed when the pumps are operating at low-flow conditions. The other problem related to potential pump damage as a result of hydraulic instability during low-flow operation. In NRC Bulletin 88-04, dated May 5, 1988, the staff requested all licensees to investigate and correct, as applicable, the two miniflow design concerns. The staff also developed a Temporary Instruction, Tl 2515/105, dated January 29, 1990 to inspect for the adequacy of licensee response and follow-up actions to NRC Bulletin 88-04. Oak Ridge National Laboratory has reviewed utility responses to Bulletin 88-04 under auspices of the NRC`s Nuclear Plant Aging Research Program, and participated in several NRC inspections. Examples of actions that have been taken, an assessment of the overall industry response, and resultant conclusions and recommendations are presented.

  14. Operating pumps on minimum flow

    Energy Technology Data Exchange (ETDEWEB)

    Casada, D.A. (Oak Ridge National Lab., TN (United States)); Li, Y.C. (Nuclear Regulatory Commission, Washington, DC (United States))

    1992-01-01

    The Nuclear Regulatory Commission (NRC) staff issued Information Notice (IN) 87-59 to alert all licensees to two miniflow design concerns identified by Westinghouse. The first potential problem discussed in this IN involves parallel pump operation. If the head/capacity curve of one of the parallel pumps is greater than the other, the weaker pump may be dead-headed when the pumps are operating at low-flow conditions. The other problem related to potential pump damage as a result of hydraulic instability during low-flow operation. In NRC Bulletin 88-04, dated May 5, 1988, the staff requested all licensees to investigate and correct, as applicable, the two miniflow design concerns. The staff also developed a Temporary Instruction, Tl 2515/105, dated January 29, 1990 to inspect for the adequacy of licensee response and follow-up actions to NRC Bulletin 88-04. Oak Ridge National Laboratory has reviewed utility responses to Bulletin 88-04 under auspices of the NRC's Nuclear Plant Aging Research Program, and participated in several NRC inspections. Examples of actions that have been taken, an assessment of the overall industry response, and resultant conclusions and recommendations are presented.

  15. Magnetic heat pump flow director

    Science.gov (United States)

    Howard, Frank S. (Inventor)

    1995-01-01

    A fluid flow director is disclosed. The director comprises a handle body and combed-teeth extending from one side of the body. The body can be formed of a clear plastic such as acrylic. The director can be used with heat exchangers such as a magnetic heat pump and can minimize the undesired mixing of fluid flows. The types of heat exchangers can encompass both heat pumps and refrigerators. The director can adjust the fluid flow of liquid or gas along desired flow directions. A method of applying the flow director within a magnetic heat pump application is also disclosed where the comb-teeth portions of the director are inserted into the fluid flow paths of the heat pump.

  16. A multiple disk centrifugal pump as a blood flow device.

    Science.gov (United States)

    Miller, G E; Etter, B D; Dorsi, J M

    1990-02-01

    A multiple disk, shear force, valveless centrifugal pump was studied to determine its suitability as a blood flow device. A pulsatile version of the Tesla viscous flow turbine was designed by modifying the original steady flow pump concept to produce physiological pressures and flows with the aid of controlling circuitry. Pressures and flows from this pump were compared to a Harvard Apparatus pulsatile piston pump. Both pumps were connected to an artificial circulatory system. Frequency and systolic duration were varied over a range of physiological conditions for both pumps. The results indicated that the Tesla pump, operating in a pulsatile mode, is capable of producing physiologic pressures and flows similar to the Harvard pump and other pulsatile blood pumps.

  17. Unintended Insulin Pump Delivery in Hyperbaric Conditions.

    Science.gov (United States)

    Bertuzzi, Federico; Pintaudi, Basilio; Bonomo, Matteo; Garuti, Fabio

    2017-04-01

    Unintended pump insulin delivery was reported to occur as a consequence of decreased atmospheric pressure, probably mediated by air bubble formation and the expansion of existing bubbles. This observation has been used to explain some hypoglycemic episodes occurring in patients on insulin pump treatment in between 1 and 1 h 45 min after the flight takeoff. New models of insulin pumps have been introduced in the market, most of them are waterproof certified. It is not clear if in these new pumps the influence of atmospheric pressure changes on the insulin delivery is still present. Moreover, there are no evidences related to the insulin pump operations in hyperbaric conditions, like as during diving activities. Our aim is therefore to verify the eventual variation of insulin pump delivery determined by atmospheric pressure changes in hyperbaric conditions. Three new models of insulin pumps were tested in hyperbaric conditions at a flow rate of 2 U/h. Atmospheric pressure variation affected pump insulin release. An increase in the atmospheric pressure from 1 to 1.3 atmosphere (ATA) induced a decrease of pump basal insulin release (about -0.2 U/10 min); conversely, when the atmospheric pressure returned from 1.3 to 1 ATA, an unintended insulin delivery was observed (about +0.3 U/10 min). This phenomenon appeared to be independent of the insulin pump rate and dependent on the presence of air bubbles within the insulin tube setting and cartridge. Unintended insulin delivery driven by atmospheric pressure changes in hyperbaric conditions occurred in the new insulin pumps available. Patients should pay attention to possible variation of insulin rate during the flight or during diving activities.

  18. Flow Characteristics of the PHTS Mechanical Pump in PGSFR

    Energy Technology Data Exchange (ETDEWEB)

    Yoon, Jung; Lee, Tae-Hoo [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of); Park, Hwi-Seob [CD-adapco, Seoul (Korea, Republic of)

    2014-10-15

    The PHTS (Primary Heat Transfer System) mechanical pump is one of the most important parts in the PGSFR. The objective of the PHTS pump is to circulate a sodium coolant to transfer the heat generated in the core to the IHTS (Intermediate Heat Transfer System). Therefore, it is important to verify the performance of the PHTS pump under various flow conditions. The flow inside the pump is a very complex multi-dimensional phenomenon that depends on the rotation speed of the pump, and the geometry of the impeller and diffuser. In particular, the pump performance and flow characteristics can be evaluated using a homologous curve represented by normalized variables of the head and torque. Using a homologous curve obtained by a real pump or model pump reduced by the same specific speed is reasonable, but the detailed design procedure about the prototype PHTS pump has not been completed at this point. In this study, the flow characteristics and homologous curve of the PHTS pump are evaluated by CFD. The flow characteristic of the PHTS pump is evaluated by the CFD. The head and torque are calculated at several flow rates and rotation speeds, and these values are substituted with normalized pump parameters. Also, the homologous head and torque curve is plotted using normalized pump parameters. This curve is used as the input of the safety analysis.

  19. Study on Driving Performance of the Axial-Flow Blood Pump under the Condition of Large Gap

    Directory of Open Access Journals (Sweden)

    Yan Xu

    2017-01-01

    Full Text Available The paper demonstrates an improvement of the simulation and computational methods for research on the system magnetic field and driving performance of the large gap magnetic drive system, which is used to drive the axial flow blood pump. The operational principle and structure of large gap magnetic drive system are narrated. Ansoft is adopted to simulate a three-dimensional driving torque to improve accuracy of computation. Experiments and theoretical study show that the use of Z10-T25 oriented silicon steel sheets as the electromagnetic core material can remarkably improve the system driving performance as well as optimize the volume and weight of the electromagnets. So the electromagnet made with oriented silicon steel sheets is conducive to improving the driving performance.

  20. Study and development of an air conditioning system operating on a magnetic heat pump cycle (design and testing of flow directors)

    Science.gov (United States)

    Wang, Pao-Lien

    1992-01-01

    This report describes the fabrication, design of flow director, fluid flow direction analysis and testing of flow director of a magnetic heat pump. The objectives of the project are: (1) to fabricate a demonstration magnetic heat pump prototype with flow directors installed; and (2) analysis and testing of flow director and to make sure working fluid loops flow through correct directions with minor mixing. The prototype was fabricated and tested at the Development Testing Laboratory of Kennedy Space Center. The magnetic heat pump uses rear earth metal plates rotate in and out of a magnetic field in a clear plastic housing with water flowing through the rotor plates to provide temperature lift. Obtaining the proper water flow direction has been a problem. Flow directors were installed as flow barriers between separating point of two parallel loops. Function of flow directors were proven to be excellent both analytically and experimentally.

  1. Magnetic Heat Pump Containing Flow Diverters

    Science.gov (United States)

    Howard, Frank S.

    1995-01-01

    Proposed magnetic heat pump contains flow diverters for suppression of undesired flows. If left unchecked, undesired flows mix substantial amounts of partially heated and partially cooled portions of working fluid, effectively causing leakage of heat from heated side to cooled side. By reducing leakage of heat, flow diverters increase energy efficiency of magnetic heat pump, potentially offering efficiency greater than compressor-driven refrigerator.

  2. Magnetic Heat Pump Containing Flow Diverters

    Science.gov (United States)

    Howard, Frank S.

    1995-01-01

    Proposed magnetic heat pump contains flow diverters for suppression of undesired flows. If left unchecked, undesired flows mix substantial amounts of partially heated and partially cooled portions of working fluid, effectively causing leakage of heat from heated side to cooled side. By reducing leakage of heat, flow diverters increase energy efficiency of magnetic heat pump, potentially offering efficiency greater than compressor-driven refrigerator.

  3. Optimization design and effect analysis of multi-operation conditions of axial-flow pump device%轴流泵多工况优化设计及效果分析

    Institute of Scientific and Technical Information of China (English)

    石丽建; 汤方平; 刘超; 谢荣盛; 谢传流; 孙丹丹

    2016-01-01

    The flow units of pump device will produce a bad flow regime when the axial-flow pump runs under off-design condition. The paper uses the numerical simulation and numerical optimization techniques, changes the geometric design parameters of axial-flow impeller, and carries out the optimization design of multi-operation conditions of axial-flow pump device. The optimization design based on pump device experiment analysis aims to improve the efficiency of operation under off-design conditions, broaden the scope of the efficiency of pump device, and reduce the operating cost of pump station. Firstly, this paper performs the parametric modeling of axial-flow impeller, and uses fewer design parameters to control the shape of pump blades by FORTRAN. According to the design condition to design an axial-flow impeller with high efficiency, and design the guide vane based on the design condition and the impeller. Use the impeller, the guide vane, and the standard inlet and outlet pipe to calculate the hydraulic performance of axial-flow pump device. Then do the experiment of the pump device to verify the accuracy and reliability of the numerical simulation of the pump device. Lastly, this paper carries out the optimization design of multi-operation conditions of axial-flow pump device. The design flow is 360 L/s, the small flow is 300 L/s and the large flow is 420 L/s, and the 3 flow conditions is chosen as the multi-operation conditions. Change the design parameters of axial-flow impeller, select the weighted average efficiency of pump device as the optimization object and the head of each condition as the constraint, and carry out the optimization design of multi-operation conditions of axial-flow pump device. For each design parameter, every change corresponds to a complete numerical simulation of pump device. Last but not least, this article does the internal flow field analysis of pump before and after optimization. The analysis mainly includes the streamline comparison

  4. Numerical analysis of cavitation within slanted axial-flow pump

    Institute of Scientific and Technical Information of China (English)

    张睿; 陈红勋

    2013-01-01

    In this paper, the cavitating flow within a slanted axial-flow pump is numerically researched. The hydraulic and cavitation performance of the slanted axial-flow pump under different operation conditions are estimated. Compared with the experimental hydraulic performance curves, the numerical results show that the filter-based model is better than the standard k-e model to predict the parameters of hydraulic performance. In cavitation simulation, compared with the experimental results, the proposed numerical method has good predicting ability. Under different cavitation conditions, the internal cavitating flow fields within slanted axial-flow pump are investigated. Compared with flow visualization results, the major internal flow features can be effectively grasped. In order to explore the origin of the cavitation performance breakdown, the Boundary Vorticity Flux (BVF) is introduced to diagnose the cavitating flow fields. The analysis results indicate that the cavitation performance drop is relevant to the instability of cavitating flow on the blade suction surface.

  5. Numerical and Experimental Study of Pump Sump Flows

    Directory of Open Access Journals (Sweden)

    Wei-Liang Chuang

    2014-01-01

    Full Text Available The present study analyzes pump sump flows with various discharges and gate submergence. Investigations using a three-dimensional large eddy simulation model and an acoustic Doppler velocimeter are performed. Flow patterns and velocity profiles in the approaching flow are shown to describe the flow features caused by various discharges and gate submergence. The variation of a large-scale spanwise vortex behind a sluice gate is examined and discussed. The suction effect on approaching flow near the pipe column is examined using numerical modeling. To gain more understanding of the vortices variation, a comparison between time-averaged and instantaneous flow patterns is numerically conducted. Additionally, swirl angle, a widely used index for evaluating pump efficiency, is experimentally and numerically examined under various flow conditions. The results indicate that the pump becomes less efficient with increasing discharge and gate submergence. The fluctuation of the free surface over the pump sump is also discussed.

  6. Analysis of vertical flow during ambient and pumped conditions in four monitoring wells at the Pantex Plant, Carson County, Texas, July-September 2008

    Science.gov (United States)

    Stanton, Gregory P.; Thomas, Jonathan V.; Stoval, Jeffery

    2009-01-01

    The Pantex Plant is a U.S. Department of Energy/National Nuclear Security Administration (USDOE/NNSA)-owned, contractor-operated facility managed by Babcock & Wilcox Technical Services Pantex, LLC (B&W Pantex) in Carson County, Texas, approximately 17 miles northeast of Amarillo. The U.S. Geological Survey, in cooperation with B&W Pantex through the USDOE/NNSA, made a series of flowmeter measurements and collected other borehole geophysical logs during July–September 2008 to analyze vertical flow in screened intervals of four selected monitoring wells (PTX01–1012, PTX06–1044, PTX06–1056, and PTX06–1068) at the Pantex Plant. Hydraulic properties (transmissivity values) of the section of High Plains (Ogallala) aquifer penetrated by the wells also were computed. Geophysical data were collected under ambient and pumped flow conditions in the four monitoring wells. Unusually large drawdowns occurred at two monitoring wells (PTX06–1044 and PTX06–1056) while the wells were pumped at relatively low rates. A decision was made to redevelop those wells, and logs were run again after redevelopment in the two monitoring wells.

  7. The influence of the flow rate on periodic flow unsteadiness behaviors in a sewage centrifugal pump

    Institute of Scientific and Technical Information of China (English)

    裴吉; 袁寿其; 袁建平; 王文杰

    2013-01-01

    To design a single-blade pump with a good performance in a wide operational range and to increase the pump reliability in the multi-conditional hydraulic design process, an understanding of the unsteady flow behaviors as related with the flow rate is very important. However, the traditional design often considers only a single design condition, and the unsteady flow behaviors have not been well studied for single-blade pumps under different conditions. A comparison analysis of the flow unsteadiness behaviors at di-fferent flow rates within the whole flow passage of the pump is carried out in this paper by solving the three-dimensional unsteady Reynolds-averaged Navier-Stokes equations with the Shear Stress Transport (SST) turbulence model. A definition of the unsteadi-ness in the pump is made and applied to analyze the unsteady intensity distributions, and the flow rate effect on the complex unsteady flow in the pump is studied quantitatively while the flow mechanism is also analyzed. The CFD results are validated by experimental data collected at the laboratory. It is shown that a significant flow rate effect on the time-averaged unsteadiness and the turbulence in-tensity distribution can be observed in both rotor and stator domains including the side chamber. The findings would be useful to re-duce the flow unsteadiness and to increase the pump reliability under multi-conditions.

  8. Flow Analysis of the Cleveland Clinic Centrifugal Pump

    Science.gov (United States)

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

    1997-01-01

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

  9. RESEARCH ON TURBULENT FLOW WITHIN THE VORTEX PUMP

    Institute of Scientific and Technical Information of China (English)

    CHEN Hong-xun

    2004-01-01

    Based on the standard k-ε turbulence model and the RANS equations, the finite volume method and the SIMPLE algorithm were adopted to carry out the three-dimensional viscous numerical simulation of the internal flow within a vortex pump in double reference frames. According to the results of numerical simulation, the internal flow in the vortex pump was analyzed, and the calculated results of blade surface pressure of the impeller were compared with experimental results. The maximum relative error is 6.6% between calculated value and experimental value of the pump head under operation conditions.

  10. Simulation of three-demensional unsteady flow in hydraulic pumps

    NARCIS (Netherlands)

    Esch, van Bartholomeus Petrus Maria

    1997-01-01

    In this thesis it is shown that the flow in hydraulic pumps of the radial and mixedflow type, operating at conditions not too far from design point, can be considered as an incompressible potential flow, where the influence of viscosity is restricted to thin boundary layers, wakes and mixing areas.

  11. Design and Simulation of Axial Flow Maglev Blood Pump

    Directory of Open Access Journals (Sweden)

    Huachun Wu

    2011-03-01

    Full Text Available The axial flow maglev blood pump (AFMBP has become a global research focus and emphasis for artificial ventricular assist device, which has no mechanical contact, mechanical friction, compact structure and light weight, can effectively solve thrombus and hemolysis. Magnetic suspension and impeller is two of the important parts in the axial flow maglev blood pump, and their structure largely determines the blood pump performance. The research adopts electromagnetic and fluid finite element analysis, and puts forward a method to design the magnetic suspension and impeller of axial flow blood pump, which tacks into account the small volume of axial blood pump. The magnetic bearing’s characteristics are evaluated by electromagnetic finite element analysis. The Blades have been designed by calculating aerofoil bone line, and make simulation analysis for different thicken ways of blade by Fluent software, and make a conclusion that the blade thickened with certain rules has better characteristics in the same conditions. The results will provide some guidance for design of axial flow maglev blood pump, and establish theoretical basis for application of the implantable artificial heart pump.

  12. TESTING THE INTERACTION OF HEART LEFT VENTRICLE AND CONTINUOUS-FLOW PUMP ON A MOCK CIRCULATION MODEL UNDER NORMAL AND PATHOLOGICAL CONDITIONS

    Directory of Open Access Journals (Sweden)

    G. P. Itkin

    2015-01-01

    Full Text Available Introduction. The preliminary study of new developed pumps for circulatory support on the hydrodynamic circulation model is an important step in the process of their designing. Hydrodynamic circulation models that can closely imitate cardio – vascular system are important to defi ne the range of effective functioning of the pumps under normal and heart disease conditions which is of great importance for defi ning the mode of these pumps in real clinical conditions.The aim of study is to create a new hydrodynamic circulation model of the systemic circulation to study the processes of interaction of heart left ventricle and continuous – fl ow pumps.Materials and methods. The main components of the mock circulation model (arterial and venous blocks are designed as closed reservoirs with an air bag providing the necessary elasticity value of these reservoirs. The heart left ventricle was simulated with an artifi cial heart ventricle with a pneumatic drive Sinus-IS which allows to change its options in a wide range. As a test pump we used the fi rst native implantable axial pump VISH – 1. In the course of research we made the registration and recording of the basic hemodynamic parameters (pressure, fl ow with a multichannel module Pumpax for the measurement of pressure parameters.Results. The designed circulation model allows to adequately reproduce the main hemodynamic parameters of the circulatory system in normal (arterial pressure – 110/77 mmHg, left atrium pressure – 7 mmHg and cardiac output – 4.2 l/min and heart failure conditions (arterial pressure – 79/53 mmHg, left atrium pressure – 15 mmHg and cardiac output – 3.1 l/min. On the circulation model the interaction of heart left ventricle and continuous-fl ow pump in heart failure simulation was studied. The dynamics of the main circulation fi gures is shown under conditions of changing of the pump rotor speed. Meanwhile, the conditions of the closing of

  13. Numerical Calculation on the Cavitation Performance of Axial Flow Pump in Multi-operating Conditions%轴流泵多工况空化特性数值计算

    Institute of Scientific and Technical Information of China (English)

    许威; 黄其柏

    2013-01-01

    The whole flow passage in an axial flow pump in different inlet velocity conditions including rated condition and off rating condition were simulated by using the computational fluid dynamics (CFD) approach based on full cavitation model. The external characteristics of the axial flow pump,pressure and vapor volume fraction distribution in different inlet flow conditions were obtained, and the cavitation performance in different conditions were analyzed. The results showed that in rated condition the pump head-flow could be well predicted by CFD simulation with an inaccuracy within 3%. While in the off rating conditions, the cavitation region and degree of cavitation were obtained. In the cavitation condition, the pressure on impeller blade surfaces decreased,and the work by the blade decreased, which results in change of the pump head and power characteristics. The vapor volume fraction distribution has similar pattern on different impeller passages but showing a certain degree of asymmetry, which is one of the factors that result in unstable operation of the axial flow pump in the cavitation condition.%基于完全空化模型,应用计算流体动力学(CFD)技术,计算了轴流泵在不同进口流量条件下的全流道流场.研究了不同进口流量条件下,轴流泵的外特性变化,叶片上的压力及空泡体积组分分布,对不同工况下的内部流场空化特性进行了分析.计算结果表明,额定流量工况下,轴流泵扬程的CFD计算值准确,与理论值误差在3%以内;非额定流量工况下,CFD计算可以得到空化发生区域及空化程度.空化发生时,叶轮叶片表面的压力下降,叶片对流体做功减少,引起水泵效率下降.各流道叶片上的空泡体积组分分布相似,但呈现出一定的非对称性,这种非对称性是造成轴流泵在空化发生时运行不稳定的因素之一.

  14. Self Calibrating Flow Estimation in Waste Water Pumping Stations

    DEFF Research Database (Denmark)

    Kallesøe, Carsten Skovmose; Knudsen, Torben

    2016-01-01

    Knowledge about where waste water is flowing in waste water networks is essential to optimize the operation of the network pumping stations. However, installation of flow sensors is expensive and requires regular maintenance. This paper proposes an alternative approach where the pumps and the waste...... water pit are used for estimating both the inflow and the pump flow of the pumping station. Due to the nature of waste water, the waste water pumps are heavily affected by wear and tear. To compensate for the wear of the pumps, the pump parameters, used for the flow estimation, are automatically...

  15. Numerical Investigation of the Performance of an Axial-Flow Pump with Tandem Blades

    Institute of Scientific and Technical Information of China (English)

    YU Zhi-yi; LIU Shu-yan; WANG Guo-yu

    2007-01-01

    The performance characteristics of an axial-flow pump with tandem blades are studied based on the numerical computations. The arrangement of the pump impellers is established through the analysis of velocity triangles. With the commercial computational fluid dynamics (CFD) software NUMECA, the turbulent flow in the tandem axial-flow pump is simulated in various flow conditions. The detail flow structure in the leading edge region of the rear impeller is described, and the i nfluence of the deflection angle of the rear blade on the head performance is studied. According to the simulation, the performance comparison is made between the tandem axial-flow pump and the conventional two-stage axial-flow pump with a uniform impeller size. Results of the study indicate that the tandem axial-flow pump can work in a wider range with high efficiency.

  16. Experimental analysis of the flow pattern of a pump turbine model in pump mode

    Science.gov (United States)

    Guggenberger, Mark; Senn, Florian; Jaberg, Helmut; Gehrer, Arno; Sallaberger, Manfred; Widmer, Christian

    2016-11-01

    Reversible pump turbines are the only means to store primary energy in an highly efficient way. Within a short time their operation can be switched between the different operational regimes thus enhancing the stabilization of the electric grid. These qualities in combination with the operation even at off-design conditions offer a high flexibility to the energy market. However, pump turbines pass through operational regimes where their behaviour becomes unstable. One of these effects occurs when the flowrate is decreased continuously down to a minimum. This point is the physical limitation of the pump operation and is very difficult to predict properly by numerical design without a model test. The purpose of the present study is to identify the fluid mechanical phenomena leading to the occurrence of instabilities of pump turbines in pump mode. A reduced scale model of a ANDRITZ pump turbine was installed on a 4-quadrant test rig for the experimental investigation of unstable conditions in pump mode. The performed measurements are based on the IEC60193-standard. Characteristic measurements at a single guide vane opening were carried out to get a detailed insight into the instabilities in pump mode. The interaction between runner and guide vane was analysed by Particle Image Velocimetry. Furthermore, high-speed visualizations of the suction side part load flow and the suction recirculation were performed. Like never before the flow pattern in the draft tube cone became visible with the help of a high-speed camera by intentionally caused cavitation effects which allow a qualitative view on the flow pattern in the draft tube cone. Suction recirculation is observed in form of single vortices separating from each runner blade and stretching into the draft tube against the main flow direction. To find an explanation for the flow phenomena responsible for the appearance of the unstable head curve also characteristic velocity distributions on the pressure side were combined

  17. High-efficiency design of a mixed-flow pump

    Institute of Scientific and Technical Information of China (English)

    KIM; Jin-Hyuk; AHN; Hyung-Jin; KIM; Kwang-Yong

    2010-01-01

    High-efficiency design of a mixed-flow pump has been carried out based on numerical analysis of a three-dimensional viscous flow.For analysis,the Reynolds-averaged Navier-Stokes equations with a shear stress transport turbulence model were discretized by finite-volume approximations.Structured grid system was constructed in the computational domain,which has O-type grids near the blade surfaces and H/J-type grids in other regions.The numerical results were validated with experimental data for the heads and hydraulic efficiencies at different flow coefficients.The hydraulic efficiency at the design flow coefficient was evaluated with variation of the geometric variables,i.e.,the area of the discharge and length of the vane in the diffuser.The result has shown that the hydraulic efficiency of a mixed-flow pump at the design condition is improved by the modification of the geometry.

  18. The Stability Conditions of the Pump Structure Vibration

    Directory of Open Access Journals (Sweden)

    Nassir Hassan Abdul Hussain Al Hariri

    2012-01-01

    Full Text Available The general approach of this research is to assume that the small nonlinearity can be separated from the linear part of the equation of motion. The effect of the dynamic fluid force on the pump structure system is considered vibrates at its natural frequency but the amplitude is determined by the initial conditions. If the motion of the system tends to increase the energy of the pump structure system, the vibration amplitude will increase and the pump structure system is considered to be unstable. A suitable MATLAB program was used to predict the stability conditions of the pump structure vibration. The present research focuses on fluid pump problems, namely, the role played by damping coefficient C, damping factor D and angular speed ? (termed the ratio ( and the determining stability of a centrifugal pump structure. The data demonstrate substantial rotor dynamic effects, a destabilizing chart appears to be inversely proportional to the D, C, and ?, and resonance changes significantly with flow rate.

  19. Using the motor to monitor pump conditions

    Energy Technology Data Exchange (ETDEWEB)

    Casada, D. [Oak Ridge National Lab., TN (United States)

    1996-12-01

    When the load of a mechanical device being driven by a motor changes, whether in response to changes in the overall process or changes in the performance of the driven device, the motor inherently responds. For induction motors, the current amplitude and phase angle change as the shaft load changes. By examining the details of these changes in amplitude and phase, load fluctuations of the driven device can be observed. The usefulness of the motor as a transducer to improve the understanding of devices with high torque fluctuations, such as positive displacement compressors and motor-operated valves, has been recognized and demonstrated for a number of years. On such devices as these, the spectrum of the motor current amplitude, phase, or power normally has certain characteristic peaks associated with various load components, such as the piston stroke or gear tooth meshing frequencies. Comparison and trending of the amplitudes of these peaks has been shown to provide some indication of their mechanical condition. For most centrifugal pumps, the load fluctuations are normally low in torque amplitude, and as a result, the motor experiences a correspondingly lower level of load fluctuation. However, both laboratory and field test data have demonstrated that the motor does provide insight into some important pump performance conditions, such as hydraulic stability and pump-to-motor alignment. Comparisons of other dynamic signals, such as vibration and pressure pulsation, to motor data for centrifugal pumps are provided. The effects of inadequate suction head, misalignment, mechanical and hydraulic unbalance on these signals are presented.

  20. Through flow analysis of pumps and fans

    Science.gov (United States)

    Neal, A. N.

    1980-08-01

    Incompressible through flow calculations in axial, mixed and centrifugal flow pumps and fans are described. An iterative scheme is used. A simple blade to blade model is applied on the surfaces of revolution defined by the meridional streamlines. This defines the fluid properties and the mean stream surface (S2 surface) for the next meridional solution. A computer program is available allowing the method to be applied for design purposes. APL is used for input and output and FORTRAN IV for computation. A typical calculation requires 30 sec of Univac 1100 time.

  1. Self Calibrating Flow Estimation in Waste Water Pumping Stations

    DEFF Research Database (Denmark)

    Kallesøe, Carsten Skovmose; Knudsen, Torben

    2016-01-01

    Knowledge about where waste water is flowing in waste water networks is essential to optimize the operation of the network pumping stations. However, installation of flow sensors is expensive and requires regular maintenance. This paper proposes an alternative approach where the pumps and the waste...... water pit are used for estimating both the inflow and the pump flow of the pumping station. Due to the nature of waste water, the waste water pumps are heavily affected by wear and tear. To compensate for the wear of the pumps, the pump parameters, used for the flow estimation, are automatically...... calibrated. This calibration is done based on data batches stored at each pump cycle, hence makes the approach a self calibrating system. The approach is tested on a pumping station operating in a real waste water network....

  2. Characterization of Pump Flow at the Grand Coulee Pumping Station for Fish Passage, 2004

    Energy Technology Data Exchange (ETDEWEB)

    Carlson, Thomas J.; Duncan, Joanne P.; Johnson, Robert L.

    2005-03-31

    This report describes a study conducted by PNNL for the Bonneville Power Administration to characterized the conditions fish experience when entrained in pump flow at the Grand Coulee Dam. PNNL used the Sensor Fish to measure the acceleration and pressure conditions that might be experienced by fish who are pulled through the pumps and turbines at Grand Coulee Dam's pump generation station and transported up into the feeder canal leading to Banks Lake. The probability that fish would be struck by the pump generating plant's new 9-bladed turbines was also calculated using Monte Carlo simulations. Our measurements showed relatively low turbulence except in the immediate vicinity of the runner environment. The highest pressure experienced by the Sensor Fish was estimated at 157 psi (the pressure gauge saturated at 155 psi). The probability of strike was also calculated, based on the average length of hatchery-reared juvenile kokanee (land-locked sockeye). Strike probabilities ranged from 0.755 for 2.36-inch fish to 0.3890 for 11.8-inch fish. The probability of strike estimates indicate that the majority (77%) of kokanne would be carried through the pump without being struck and most likely without injury resulting from pressure and turbulence exposure. Of the 23% that might be struck it is expected that 60% would arrive in Banks Lake without visible external injuries. Thus more than 90% of entrained fish would be expected to arrive in Banks Lake without injury.

  3. Pipe flow of pumping wet shotcrete based on lubrication layer

    National Research Council Canada - National Science Library

    Chen, Lianjun; Liu, Guoming; Cheng, Weimin; Pan, Gang

    2016-01-01

    .... The paper studied the pipe flow law of wet shotcrete based on lubrication layer by build the experimental pumping circuit of wet shotcrete that can carry out a number of full-scale pumping tests...

  4. Performance prediction and flow analysis in the vaned distributor of a pump turbine under low flow rate in pump mode

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    The main goal of this work is to investigate the possible different flow patterns existing in pump turbine under off-design conditions in pump mode. Numerical simulations by solving the Navier-Stokes equation, coupled with the "SST k-ω" turbulence model, were carried out. Flow characteristics were assumed to be stalled in the appropriate region of ?ow rate levels of Q/QD=0.15–0.61. The simulation result was compared with experimental data and they showed good agreement. Consequently, velocity fields in three axial locations in stay vanes and guide vanes were analysed in details. It was shown that "jet-wake" flow pattern exists near the band, which changes little in the whole shape with flow rate increasing; to the middle location of vanes, reverse flow begins to appear on the interface between the runner and guide vanes, which will disappear gradually as the flow rate increases; massive reverse flow is captured near the crown, whose intensity will be weakened as the flow rate increases. Ultimately, it was found that the special head-flow profile can be ascribed to the special hydraulic loss characteristics of the stay vanes and guide vanes.

  5. PIV Experimental Investigation on the Flow in a Model of Closed Pump Sump

    Institute of Scientific and Technical Information of China (English)

    MANSA Kante; ZHANG Botao(张波涛); LI Xiaoming(李小明); LI Yong(李永); WU Yulin(吴玉林)

    2003-01-01

    Vortices in the flow of a pump sump present an important problem in pump station operation. In the present study, the flow patterns in two model pump sumps with specially designed structures are analyzed using the particle image velocimetry (PIV) technique. The data is analyzed to reveal a number of parameters including the internal flow field with velocity distribution, the streamline distribution, and the turbulent kinetic energy. The analysis certifies that a modified pump with added T-type baffle below the sump exhibits good performance for realistic working conditions.

  6. Investigation on Flow-Induced Noise due to Backflow in Low Specific Speed Centrifugal Pumps

    Directory of Open Access Journals (Sweden)

    Qiaorui Si

    2013-01-01

    Full Text Available Flow-induced noise causes disturbances during the operation of centrifugal pumps and also affects their performance. The pumps often work at off-design conditions, mainly at part-load conditions, because of frequent changes in the pump device system. Consequently numerous unstable phenomena occur. In low specific speed centrifugal pumps the main disturbance is the inlet backflow, which is considered as one of the most important factors of flow-induced noise and vibration. In this study, a test rig of the flow-induced noise and vibration of the centrifugal pump was built to collect signals under various operating conditions. The three-dimensional unsteady flow of centrifugal pumps was calculated based on the Reynolds-averaged equations that resemble the shear stress transport (SST k-ω turbulence model. The results show that the blade passing frequency and shaft frequency are dominant in the spectrum of flow-induced noise, whereas the shaft component, amplitude value at shaft frequency, and peak frequencies around the shaft increase with decreasing flow. Through flow field analysis, the inlet backflow of the impeller occurs under 0.7 times the design flow. The pressure pulsation spectrum with backflow conditions validates the flow-induced noise findings. The velocity characteristics of the backflow zone at the inlet pipe were analyzed, and the dynamic characteristics of the backflow eddy during one impeller rotating period were simultaneously obtained by employing the backflow conditions. A flow visualization experiment was performed to confirm the numerical calculations.

  7. Unstable Head-Flow Characteristic Generation Mechanism of a Low Specific Speed Mixed Flow Pump

    Institute of Scientific and Technical Information of China (English)

    Masahiro MIYABE; Hideaki MAEDA; Isamu UMEKI; Yoshinori JITTANI

    2006-01-01

    This paper treats the flow instabilities in a mixed flow pump with a vaned diffuser. Test pump has a positive slope of a head-flow performance curve at 65% flow rate of BEP (Best Efficiency Point) because of a rotating stall.Dynamic Particle Image Velocimetry (PIV) and pressure fluctuation measurements are used for investigating the propagation mechanism of a rotating stall. It was found that unstable performance was caused by periodical large scale abrupt backflow generated from the vaned diffuser to the outlet of impeller. Further, the relation between the static pressure at the inlet of diffuser vane and the internal flow condition was clarified. From these experimental results, in order to improve the positive slope of a head-flow performance curve, to suppress the growth of strong vortex toward the inlet of diffuser vane was proved to be a key point.

  8. Flow Separation and Turbulence in Jet Pumps for Thermoacoustic Applications

    NARCIS (Netherlands)

    Oosterhuis, Joris P.; Verbeek, Anton A.; Bühler, Simon; Wilcox, Douglas; Meer, van der Theo H.

    2016-01-01

    The effect of flow separation and turbulence on the performance of a jet pump in oscillatory flows is investigated. A jet pump is a static device whose shape induces asymmetric hydrodynamic end effects when placed in an oscillatory flow. This will result in a time-averaged pressure drop which can be

  9. Condition monitoring of rotary blood pumps.

    Science.gov (United States)

    Jammu, V B; Malanoski, S; Walter, T; Smith, W

    1997-01-01

    Long-term, trouble-free operation of ventricular assist devices (VADs) is critical to the patient. A catastrophic failure of the VAD could cost the patient's life, thus defeating the purpose of the device. The targeted 90% 5 year reliability also implies that the average device life would exceed the 5 year limit. Time based explantation of the device after the fifth year will replace many devices with significant additional life, subject the patient to unnecessary surgical risk, and increase costs. To preclude the need for time based replacements and prevent catastrophic failures, a condition monitor is proposed in this article for early detection of faults in VADs. To develop this monitor, the effectiveness of various sensing and monitoring methods for determining the VAD condition is investigated. A Hemadyne pump was instrumented with a set of eight sensors, and a series of experiments were performed to record and analyze signals from the normal and abnormal pumps with five different faults. Statistical, spectral, envelope, and ensemble averaging analyses were performed to characterize changes in sensor signals due to faults. Experimental results indicate that statistical and frequency information from the acceleration and dynamic pressure signals can clearly detect and identify various VAD faults.

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

    Science.gov (United States)

    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

  11. 半开式离心泵变工况叶顶间隙的流动特性%Flow characteristics of blade tip clearance in semi-open centrifugal pump in variable condition

    Institute of Scientific and Technical Information of China (English)

    贾晓奇; 聂小林; 涂必成; 崔宝玲

    2015-01-01

    The centrifugal pumps with semi-open impellers have been widely applied in petrol chemical industry, aerospace industry, power energy, etc. The tip clearance flow is a very complex turbulent flow in which the vortex, secondary flow, and recirculation flow are existent simultaneously, and it plays an important role for internal flow characteristics and external performances. In recent years, lots of numerical and experimental studies have been carried out to investigate the tip clearance flow and improve the performance of the semi-open impeller centrifugal pump. In this paper, numerical simulation and performance test are carried out on the centrifugal pump with a semi-open impeller. Influences of tip clearance on performance and the details of flow in tip clearance layer are studied at four different flow rate conditions. In the numerical simulation, the PRO/E software is used to generate computational geometries. The compatible preprocessor, GAMBIT is used to generate meshes. The commercial CFD software Fluent 6.3 is used to solve the N–S equations. The SIMPLEC algorithm is used to couple pressure and velocity. Second order upwind discretizations have been used for convection terms and the central difference schemes are used for diffusion terms. Three-dimensional viscous incompressible flow field simulations have been performed using multiple reference frame coordinates. The impeller and inducer region is taken as a rotating reference frame with a constant angular speed of 1 450 r/min, and the other surfaces are defined as stationary reference frame. And the boundary conditions are velocity condition at inlet and outflow at outlet of the pump. Also, no-slip wall conditions have been used for the rest surfaces of the pump. Also, the experimental studies are carried out on the tested centrifugal pump with tip clearances of 1.0 mm, and the results are compared with the numerical calculations. Seal gaskets are used to adjust the tip clearance. Tungsten wires (the

  12. Experimental Investigation and Passive Flow Control of a Cavitating Centrifugal Pump

    Directory of Open Access Journals (Sweden)

    Spyridon D. Kyparissis

    2012-01-01

    Full Text Available Passive flow control techniques are used to improve the flow field and efficiency of centrifugal pumps and turbomachines, in general. An important phenomenon that mechanical engineers have to take into account is cavitation. It leads to the decrease of the pump performance and total head. In the present experimental study, a centrifugal pump is investigated in cavitating conditions. A passive flow control is realized using three different blade leading edge angles in order to reduce the cavitation development and enhance the pump performance. The experiments are carried out in a pump test rig specially designed and constructed, along with the impellers. The head drop and total efficiency curves are presented in order to examine the effect of the blade leading edge angle on the cavitation and pump performance. Finally, the vapour distribution along with the blades is illustrated for the tested blade leading edge angles.

  13. Effects of structural parameters and rigidity of driving diaphragm on flow characteristics of micro valveless pump

    Institute of Scientific and Technical Information of China (English)

    谢海波; 傅新; 杨华勇

    2003-01-01

    The structure and operating principle of micro valveless pump were investigated theoretically and experimentally. The mathematical model of pressure and flow rate within the micro nozzle/diffuser was established to analyze the effects of nozzle/diffuser parameters on the output flow rate of the micro valveless pump.The experiments were carried out with different structural parameters, driving frequencies, vibration amplitudes and stiffness of the driving diaphragms. Effects of the structural parameters and driving conditions on the operation performance of the pump are discussed in detail. The work provides useful reference for structure optimization selection of the driving diaphragm of micro valveless pump.

  14. Effects of structural parameters and rigidity of driving diaphragm on flow characteristics of micro valveless pump

    Institute of Scientific and Technical Information of China (English)

    谢海波; 傅新; 杨华勇

    2003-01-01

    The structure and operating principle of micro valveless pump were investigated theoretically and experimentally. The mathematical model of pressure and flow rate within the micro nozzle/diffuser was established to analyze the effects of nozzle/diffuser parameters on the output flow rate of the micro valveless pump. The experiments were carried out with different structural parameters, driving frequencies, vibration amplitudes and stiffness of the driving diaphragms. Effects of the structural parameters and driving conditions on the operation performance of the pump are discussed in detail. The work provides useful reference for structure optimization selection of the driving diaphragm of micro valveless pump.

  15. 3-D PIV Test of Inner Flow in a Double-blade Pump under Zero Flow Rate Condition%零流量工况下双叶片泵内部流场三维PIV测量

    Institute of Scientific and Technical Information of China (English)

    王凯; 刘厚林; 袁寿其; 谈明高; 杨东升

    2011-01-01

    Inner flow in a double-blade pump impeller, whose specific speed is 111, was measured under zero flow rate condition by using 3-D PIV test technology. In order to ensure the accuracy of 3-D PIV test, the external trigger synchronization system which was made with fiber optic and equivalent calibration method was applied. In Visual C+ + 2005 platform, according to the velocity triangle, 3-D PIV velocity synthetic procedure was compiled to obtain the relative velocity synthesized by the absolute velocity and the circular velocity. The results showed that volute tongue had greater impact on the absolute velocity field within the impeller. There were vortices regions at three measurement surfaces within impeller, but the sizes and locations of vortices were different. Moreover, there was a low velocity region at the volute diffuser, the absolute velocity values in the region were less than 0. 62 m/s, and there were vortices at the volute diffuser. The axial velocities values of impeller passage, volute diffuser and region near volute tongue were different at three measurement planes.%采用三维PIV测试技术对一比转数为111的双叶片泵零流量工况下的内部流动进行了测量.采用基于光纤制作的外触发同步系统和等效标定方法等关键技术来保证三维PIV测试精度.在Visual C++2005平台下,根据速度三角形,编写了三维PIV速度合成程序,将测量的绝对速度与圆周速度合成得到相对速度.结果表明:隔舌对叶轮内绝对速度场影响较大;叶轮流道内3个测量平面上都存在较大范围的漩涡区,但漩涡的大小、位置有所不同;蜗壳扩散段存在低速区域,该区域的绝对速度小于0.62 m/s,且存在漩涡现象;3个测量平面上,叶轮流道内、蜗壳扩散段及隔舌附近区域的轴向速度各不相同.

  16. A study on diagnostic techniques of pump operating condition

    Energy Technology Data Exchange (ETDEWEB)

    Cho, Du Eon; Park, Jong Ho; Song, Gyu Jo; Shin, Pil Kwon; Lee, Nam Gil; Shin, Wan Sun; Kang, Hyeon Taek; Lee, Taek Sang [Chungnam National Univ., Taejon (Korea, Republic of)

    1998-03-15

    The scope and contents investigate and reviewed are as follows : establishment of study plan and references survey, review of related problems and inservice test standards of safety injection pump in use nuclear power plant, review of the study results in laboratory, the theoretical investigation of temperature rise according to mini-flow rate of pump, mini-flow rate working characteristics of high and low pressure injection pumps at nuclear power plants, setup of testing equipment for measuring ampere, discharge pressure and vibration, selection and behaviors analysis of major parameters concerning pump degradation.

  17. Minimal sensor count approach to fuzzy logic rotary blood pump flow control.

    Science.gov (United States)

    Casas, Fernando; Ahmed, Nisar; Reeves, Andrew

    2007-01-01

    A rotary blood pump fuzzy logic flow controller without flow sensors was developed and tested in vitro. The controller, implemented in LabView, was set to maintain a flow set point in the presence of external pressure disturbances. Flow was estimated as a function of measured pump's delta P and speed, using a steady-state, nonlinear approximation. The fuzzy controller used the pump's flow estimate and delta P as feedback variables. The defuzzified control output manipulated the pump speed. Membership functions included flow error, delta P, and pump speed. Experimental runs in a mock loop (water/glycerin 3.5 cPs, 37 degrees C), using the estimated flow, were compared with those using a Transonic flow meter for nine conditions of flow and delta P (4 to 6 L/min, 150 to 350 mm Hg). Pressure disturbances generated by a servo pinch valve ranged from +/-23 to +/-47 mm Hg. Results indicated that the fuzzy controller ably regulated the flow set point to within +/-10% of the baseline even under large swings in pressure. There was no difference in controller performance between the ultrasonic flow measurement and the estimated flow calculation scenarios. These tests demonstrated that the fuzzy controller is capable of rejecting disturbances and regulating flow to acceptable limits while using a flow estimate.

  18. Development of a miniature intraventricular axial flow blood pump.

    Science.gov (United States)

    Yamazaki, K; Umezu, M; Koyanagi, H; Outa, E; Ogino, S; Otake, Y; Shiozaki, H; Fujimoto, T; Tagusari, O; Kitamura, M

    1993-01-01

    A new intraventricular axial flow blood pump has been designed and developed as a totally implantable left ventricular assist device (LVAD). This pump consists of an impeller combined with a guide-vane, a tube housing, and a DC motor. The pump is introduced into the LV cavity through the LV apex, and the outlet cannula is passed antegrade across the aortic valve. Blood is withdrawn from the LV through the inlet ports at the pump base, and discharged to the ascending aorta. Our newly developed axial flow pump system has the following advantages: 1) it is a simple and compact system, 2) minimal blood stasis both in the device and the LV cavity, 3) minimal blood contacting surface of the pump, 4) easy accessibility with a less invasive surgical procedure, and 5) low cost. A pump flow > 5 L/min was obtained against 100 mmHg differential pressure in the mock circulatory system. The pump could produce a passive pulsatile flow effect with a beating heart more efficiently than other non-pulsatile pumps because of minimal pressure drop and inertia along the bypass tract. Anatomic fit studies using dissected hearts of dilated cardiomyopathy (DCM) cadavers showed that this pump could smoothly pass through the aortic valve without any interference with mitral valve function. Recently, a dynamic pressure groove bearing and a miniature lip seal have been developed. The dynamic pressure groove bearing has a simple structure and acts as a pressure resistant sealing mechanism.(ABSTRACT TRUNCATED AT 250 WORDS)

  19. Development and numerical analysis of low specific speed mixed-flow pump

    Science.gov (United States)

    Li, H. F.; Huo, Y. W.; Pan, Z. B.; Zhou, W. C.; He, M. H.

    2012-11-01

    With the development of the city, the market of the mixed flow pump with large flux and high head is prospect. The KSB Shanghai Pump Co., LTD decided to develop low speed specific speed mixed flow pump to meet the market requirements. Based on the centrifugal pump and axial flow pump model, aiming at the characteristics of large flux and high head, a new type of guide vane mixed flow pump was designed. The computational fluid dynamics method was adopted to analyze the internal flow of the new type model and predict its performances. The time-averaged Navier-Stokes equations were closed by SST k-ω turbulent model to adapt internal flow of guide vane with larger curvatures. The multi-reference frame(MRF) method was used to deal with the coupling of rotating impeller and static guide vane, and the SIMPLEC method was adopted to achieve the coupling solution of velocity and pressure. The computational results shows that there is great flow impact on the head of vanes at different working conditions, and there is great flow separation at the tailing of the guide vanes at different working conditions, and all will affect the performance of pump. Based on the computational results, optimizations were carried out to decrease the impact on the head of vanes and flow separation at the tailing of the guide vanes. The optimized model was simulated and its performance was predicted. The computational results show that the impact on the head of vanes and the separation at the tailing of the guide vanes disappeared. The high efficiency of the optimized pump is wide, and it fit the original design destination. The newly designed mixed flow pump is now in modeling and its experimental performance will be getting soon.

  20. Statistical characteristics of suction pressure signals for a centrifugal pump under cavitating conditions

    Science.gov (United States)

    Li, Xiaojun; Yu, Benxu; Ji, Yucheng; Lu, Jiaxin; Yuan, Shouqi

    2017-02-01

    Centrifugal pumps are often used in operating conditions where they can be susceptible to premature failure. The cavitation phenomenon is a common fault in centrifugal pumps and is associated with undesired effects. Among the numerous cavitation detection methods, the measurement of suction pressure fluctuation is one of the most used methods to detect or diagnose the degree of cavitation in a centrifugal pump. In this paper, a closed loop was established to investigate the pump cavitation phenomenon, the statistical parameters for PDF (Probability Density Function), Variance and RMS (Root Mean Square) were used to analyze the relationship between the cavitation performance and the suction pressure signals during the development of cavitation. It is found that the statistical parameters used in this research are able to capture critical cavitation condition and cavitation breakdown condition, whereas difficult for the detection of incipient cavitation in the pump. At part-load conditions, the pressure fluctuations at the impeller inlet show more complexity than the best efficiency point (BEP). Amplitude of PDF values of suction pressure increased steeply when the flow rate dropped to 40 m3/h (the design flow rate was 60 m3/h). One possible reason is that the flow structure in the impeller channel promotes an increase of the cavitation intensity when the flow rate is reduced to a certain degree. This shows that it is necessary to find the relationship between the cavitation instabilities and flow instabilities when centrifugal pumps operate under part-load flow rates.

  1. Experimental and numerical analysis of unsteady behaviour of high efficiency mixed-flow pump

    Directory of Open Access Journals (Sweden)

    Sedlář Milan

    2014-03-01

    Full Text Available This work deals with the experimental and numerical investigation of cavitating and noncavitating flow inside a mixed-flow pump and its influence on performance curves of this pump. The experimental research has been carried out in the closed horizontal loop with the main tank capacity of 35 m3. The loop is equipped with both the compressor and the vacuum pump capable of creating different pressure levels while maintaining constant volume flow rate. Pump investigated in this project has been equipped with transparent windows, which enabled the visualization of flow and cavitation phenomena for a wide range of flow conditions. A comprehensive CFD analysis of tested pump has been done both in the cavitating and noncavitating regimes. The ANSYS CFX commercial CFD package has been used to solve URANS equations together with the Rayleigh-Plesset model and the SST-SAS turbulence model. Both the experimental research and the CFD analysis have provided a good illustration of the flow structures inside the pump and their dynamics for a wide range of flow rates and NPSH values. Flow and cavitation instabilities have been detected at suboptimal flow rates which correspond to increased values of noise and vibrations. The calculated results agree well with the measurements.

  2. Experimental and numerical analysis of unsteady behaviour of high efficiency mixed-flow pump

    Science.gov (United States)

    Sedlář, Milan; Komárek, Martin; Vyroubal, Michal; Doubrava, Vít; Varchola, Michal; Hlbočan, Peter

    2014-03-01

    This work deals with the experimental and numerical investigation of cavitating and noncavitating flow inside a mixed-flow pump and its influence on performance curves of this pump. The experimental research has been carried out in the closed horizontal loop with the main tank capacity of 35 m3. The loop is equipped with both the compressor and the vacuum pump capable of creating different pressure levels while maintaining constant volume flow rate. Pump investigated in this project has been equipped with transparent windows, which enabled the visualization of flow and cavitation phenomena for a wide range of flow conditions. A comprehensive CFD analysis of tested pump has been done both in the cavitating and noncavitating regimes. The ANSYS CFX commercial CFD package has been used to solve URANS equations together with the Rayleigh-Plesset model and the SST-SAS turbulence model. Both the experimental research and the CFD analysis have provided a good illustration of the flow structures inside the pump and their dynamics for a wide range of flow rates and NPSH values. Flow and cavitation instabilities have been detected at suboptimal flow rates which correspond to increased values of noise and vibrations. The calculated results agree well with the measurements.

  3. Centrifugal pumps

    CERN Document Server

    Anderson, HH

    1981-01-01

    Centrifugal Pumps describes the whole range of the centrifugal pump (mixed flow and axial flow pumps are dealt with more briefly), with emphasis on the development of the boiler feed pump. Organized into 46 chapters, this book discusses the general hydrodynamic principles, performance, dimensions, type number, flow, and efficiency of centrifugal pumps. This text also explains the pumps performance; entry conditions and cavitation; speed and dimensions for a given duty; and losses. Some chapters further describe centrifugal pump mechanical design, installation, monitoring, and maintenance. The

  4. Investigation of the correlation between noise and vibration characteristics and unsteady flow in a circulator pump

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Denghao; Ren, Yun; Mou, Jiegang; Gu, Yunqing [Zhejiang University of Technology, Hangzhou (China)

    2017-05-15

    Circulator pumps have wide engineering applications but the acoustics, vibration and unsteady flow structures of the circulator pump are still not fully understood. We investigated the noise and vibration characteristics and unsteady flow structures in a circulator pump at different flow rates. Three-dimensional, unsteady RANS equations were solved on high-quality structured meshes with SST k-ω turbulence model numerically. Measurements were made in a semi-anechoic chamber to get an overview of noise and vibration level of a pump at different flow rates. The 1/3 octave-band filter technique was applied to obtain the explicit frequency spectra of sound, pressure fluctuations and vibration signals and their principal frequencies were identified successfully. The air-borne noise level of the designed condition is lower than that of the off-design conditions, and the highest sound pressure level is found at part-load condition. The acoustic emission from the pump is mainly caused by unsteady flow structures and pressure fluctuations. In addition, both the link between air- borne noise and pressure fluctuation, and the correlation between vibration and unsteady hydrodynamic forces, were quantitatively examined and verified. This work offers good data to understand noise and vibration characteristics of circulator pumps and the relationships among the noise, vibration and unsteady flow structures.

  5. Numerical Flow Analysis of a Hydraulic Gear Pump

    Science.gov (United States)

    Panta, Yogendra M.; Kim, Hyun W.; Pierson, Hazel M.

    2007-11-01

    The pressure that exists at the outlet port of a gear pump is a result of system load that was created by a resistance to the fluid flow. However, the flow pattern created inside an external gear pump by the motion of two oppositely rotating gears is deceptively complex, despite the simple geometry of the gear pump. The flow cannot be analyzed, based on a steady-state assumption that is usually employed to analyze turbo-machinery although the flow is essentially steady. Only the time-dependent, transient analysis with moving dynamic meshing technique can predict the motion of the fluid flow against the very high adverse pressure distribution. Although the complexity of analysis is inherent in all positive displacement pumps, gear pumps pose an exceptional challenge in modeling due to the fact that there are two rotating components that are housed within a stationary casing and the gears must be in contact with each other all the time. Fluent, commercially available computational fluid dynamics (CFD) software was used to analyze the flow of the gear pump. The investigation done by CFD produced significant information on flow patterns, velocity and pressure fields, and flow rates.

  6. Validation of an axial flow blood pump: computational fluid dynamics results using particle image velocimetry.

    Science.gov (United States)

    Su, Boyang; Chua, Leok Poh; Wang, Xikun

    2012-04-01

    A magnetically suspended axial flow blood pump is studied experimentally in this article. The pump casing enclosed a three-blade straightener, a two-blade impeller shrouded by a permanent magnet-embedded cylinder, and a three-blade diffuser. The internal flow fields were simulated earlier using computational fluid dynamics (CFD), and the pump characteristic curves were determined. The simulation results showed that the internal flow field was basically streamlined, except the diffuser region. Particle image velocimetry (PIV) measurement of the 1:1 pump model was conducted to validate the CFD result. In order to ensure the optical access, an acrylic prototype was fabricated with the impeller driven by a servomotor instead, as the magnet is opaque. In addition to the transparent model, the blood analog fluid with the refractive index close to that of acrylic was used to avoid refraction. According to the CFD results, the axial flow blood pump could generate adequate pressure head at the rotating speed of 9500rpm and flow rate of 5L/min, and the same flow condition was applied during the PIV measurement. Through the comparisons, it was found that the experimental results were close to those obtained by CFD and had thus validated the CFD model, which could complement the limitation of the measurement in assessing the more detailed flow fields of the axial flow pump.

  7. Computer-controlled positive displacement pump for physiological flow simulation.

    Science.gov (United States)

    Holdsworth, D W; Rickey, D W; Drangova, M; Miller, D J; Fenster, A

    1991-11-01

    A computer-controlled pump for use both in the study of vascular haemodynamics and in the calibration of clinical devices which measure blood flow is designed. The novel design of this pump incorporates two rack-mounted pistons, driven into opposing cylinders by a micro-stepping motor. This approach allows the production of nearly uninterrupted steady flow, as well as a variety of pulsatile waveforms, including waveforms with reverse flow. The capabilities of this pump to produce steady flow from 0.1 to 60 ml s-1, as well as sinusoidal flow and physiological flow, such as that found in the common femoral and common carotid arteries are demonstrated. Cycle-to-cycle reproducibility is very good, with an average variation of 0.1 ml s-1 over thousands of cycles.

  8. NUMERICAL SIMULATION OF 3-D TURBULENT FLOW IN THE MULTI- INTAKES SUMP OF THE PUMP STATION

    Institute of Scientific and Technical Information of China (English)

    CHEN Hong-xun; GUO Jia-hong

    2007-01-01

    In this article, a numerical model for three-dimensional turbulent flow in the sump of the pump station was presented. A reasonable boundary condition for the flow in the sump with several water intakes at different flow rates was proposed. The finite volume method was employed to solve the governing equations with the body fitted grid generated by the multi-block grid technique. By using the Fluent software, the fluid flow in a model sump of the pump station was calculated. Compared with the experimental result, the numerical result of the example is fairly good.

  9. Hydrodynamic Analysis of the Flow in an Axial Rotor and Impeller for Large Storage Pump

    Science.gov (United States)

    Bosioc, A. I.; Muntean, S.; Draghici, I.; Anton, L. E.

    2016-11-01

    In hydropower systems among hydropower plants there are integrated pumping stations (PS). In order to ensure higher flow rate, the pumps have constructive differences besides regular. Consequently, the complex shape of the suction-elbow with symmetric inlet generates an unsteady flow which is ingested by impeller. These phenomena's also generate stronger unsteady flow conditions, such as stall, wakes, turbulence and pressure fluctuations, which affect the overall mechanical behaviour of the pump with vibration, noise and radial and axial forces on the rotor. Alternatively, an axial rotor can be installed in front of the impeller. In this case, the flow non-uniformity will be decreased and the static pressure will be increased at the impeller inlet. Consequently, the efficiency behaviour practically remains unchanged while the cavitational behaviour is improved. From the assembly between axial rotor and centrifugal impeller, the axial rotor usually works in cavitation and is often replaced. The paper investigates experimentally and numerically the comparison between pump impeller without and with axial rotor hydrodynamics taking into account the flow given by the symmetrical suction elbow. Full three-dimensional turbulent numerical investigation of the symmetrical suction elbow, with axial rotor and without, pump impeller and volute are performed. The hydrodynamic analysis confirms that once the axial rotor is mounted in front of the pump impeller increase the static pressure and the incidence angle is improved at the inlet of the pump impeller.

  10. The helical flow pump with a hydrodynamic levitation impeller.

    Science.gov (United States)

    Abe, Yusuke; Ishii, Kohei; Isoyama, Takashi; Saito, Itsuro; Inoue, Yusuke; Ono, Toshiya; Nakagawa, Hidemoto; Nakano, Emiko; Fukazawa, Kyoko; Ishihara, Kazuhiko; Fukunaga, Kazuyoshi; Ono, Minoru; Imachi, Kou

    2012-12-01

    The helical flow pump (HFP) is a novel rotary blood pump invented for developing a total artificial heart (TAH). The HFP with a hydrodynamic levitation impeller, which consists of a multi-vane impeller involving rotor magnets, stator coils at the core position, and double helical-volute pump housing, was developed. Between the stator and impeller, a hydrodynamic bearing is formed. Since the helical volutes are formed at both sides of the impeller, blood flows with a helical flow pattern inside the pump. The developed HFP showed maximum output of 19 l/min against 100 mmHg of pressure head and 11 % maximum efficiency. The profile of the H-Q (pressure head vs. flow) curve was similar to that of the undulation pump. Hydrodynamic levitation of the impeller was possible with higher than 1,000 rpm rotation speed. The normalized index of the hemolysis ratio of the HFP to centrifugal pump (BPX-80) was from 2.61 to 8.07 depending on the design of the bearing. The HFP was implanted in two goats with a left ventricular bypass method. After surgery, hemolysis occurred in both goats. The hemolysis ceased on postoperative days 14 and 9, respectively. In the first experiment, no thrombus was found in the pump after 203 days of pumping. In the second experiment, a white thrombus was found in the pump after 23 days of pumping. While further research and development are necessary, we are expecting to develop an excellent TAH with the HFP.

  11. Functioning conditions of the Casale pumping station in Mantova, Italy

    Directory of Open Access Journals (Sweden)

    C. Capponi

    2014-03-01

    Full Text Available This paper aims to analyze data provided by TeaAcque for Casale pumping station in Mantova, Italy. A~model based on the affinity laws is used to simulate the behavior of the Casale pumping station where variable speed pumps (VSPs are installed. Quadratic and cubic polynomial curves are used to fit the pump data given by the affinity laws. Such curves can be used to predict the efficiency when the functioning conditions change. The relationship between the variation in the rotation speed and the efficiency is also derived.

  12. Performance analysis of axial flow pump on gap changing between impeller and guide vane

    Science.gov (United States)

    Wang, W. J.; Liang, Q. H.; Wang, Y.; Yang, Y.; Yin, G.; Shi, X. X.

    2013-12-01

    In order to study the influence on gap changing of the static and dynamic components in axial flow pump, the axial flow pump model (TJ04-ZL-06) that used in the eastern of south-to-north water diversion project was selected. Steady turbulence field with different gaps was simulated by standard κ-ε turbulence model and double-time stepping methods. Information on the pressure distribution and velocity distribution of impeller surfaces were obtained. Then, calculated results were compared with the test results and analyzed. The results show that the performance of pump is not sensitive with the axial gap width under design conditions and the large flow rate condition. With increasing gap width, it will be improved in low flow rate condition. The attack angle of impeller inlet in small flow rate condition become small and the flow separation phenomenon can be observed in this condition. The axial velocity distribution of impeller outlet is nonlinear and to increase the axial gap is to improve the flow pattern near the hub effectively. The trend of calculating results is identical with test. It will play a guiding role to the axial pump operation and design in south-to-north water diversion project.

  13. A numerical investigation on the vortex formation and flow separation of the oscillatory flow in jet pumps

    CERN Document Server

    Oosterhuis, Joris P; Wilcox, Douglas; van der Meer, Theo

    2015-01-01

    A two-dimensional computational fluid dynamics model is used to predict the oscillatory flow through a tapered cylindrical tube section (jet pump) placed in a larger outer tube. Due to the shape of the jet pump, there will exist an asymmetry in the hydrodynamic end effects which will cause a time-averaged pressure drop to occur that can be used to cancel Gedeon streaming in a closed-loop thermoacoustic device. The performance of two jet pump geometries with different taper angles is investigated. A specific time-domain impedance boundary condition is implemented in order to simulate traveling acoustic wave conditions. It is shown that by scaling the acoustic displacement amplitude to the jet pump dimensions, similar minor losses are observed independent of the jet pump geometry. Four different flow regimes are distinguished and the observed flow phenomena are related to the jet pump performance. The simulated jet pump performance is compared to an existing quasi-steady approximation which is shown to only be ...

  14. Applicability of sewage heat pump air-conditioning system

    Institute of Scientific and Technical Information of China (English)

    陈金华; 刘猛; 刘勇; 靳鸣; 陈洁

    2009-01-01

    A sewage heat pump system and its application based on a project in Chongqing,China,were discussed. Based on the sewage conditions,a feasibility analysis of the sewage heat pump air conditioning system was conducted. The theoretical and quantitative calculations indicate that sewage flux in the city sewage main pipe in the project can satisfy heat exchange requirements,and taking water from the pipes has relatively small influence on the pipe net in summer and winter. The sewage heat pump air-conditioning system can save 21.5% operating cost in one year,which is energy efficient and environmentally friendly.

  15. Experimental investigations on a common centrifugal pump operating under gas entrainment conditions

    Energy Technology Data Exchange (ETDEWEB)

    Schäfer, Thomas, E-mail: thomas.schaefer@hzdr.de [Helmholtz-Zentrum Dresden-Rossendorf, Institute of Fluid Dynamics (Germany); Neumann, Martin [Technische Universität Dresden, AREVA Endowed Chair of Imaging Techniques in Energy and Process Engineering (Germany); Bieberle, André [Helmholtz-Zentrum Dresden-Rossendorf, Institute of Fluid Dynamics (Germany); Hampel, Uwe [Helmholtz-Zentrum Dresden-Rossendorf, Institute of Fluid Dynamics (Germany); Technische Universität Dresden, AREVA Endowed Chair of Imaging Techniques in Energy and Process Engineering (Germany)

    2017-05-15

    Highlights: • The pump performance has been evaluated for several gas entrainment conditions. • The gas entraining flow regime has a large impact on the pump performance. • High-resolution gamma-ray computed tomography (HireCT) has been applied. • Gas holdup inside the operating impeller has been visualized and quantified. • Gas holdup profiles along selected streamlines have been calculated. - Abstract: This paper presents an experimental study on the effects of additional gas entrainment in centrifugal pumps designed for conveying liquid phases only. The pump performance has been evaluated for several gas entrainment conditions, and for various operational settings of the pump, such as its alignment and the rotational speed of the impeller. As a main performance indicator the impact of entrained gas on the hydraulic power of the pump has been analyzed using experimental data. Additionally, high-resolution gamma-ray computed tomography (HireCT) operated in time-averaged rotation-synchronized scanning mode has been applied to quantify local phase fraction distributions inside the rapidly rotating pump impeller. Based on these quantitative tomographic measurements, gas holdup profiles along selected streamlines have been calculated and gas accumulation areas inside the impeller chambers have been visualized. Thus, various internally accumulated gas holdup patterns have been identified and, eventually, associated with characteristic pump performance behaviors. Moreover, the tomographic measuring method allowed an enhanced gas holdup analysis in specified pump compartments. As a result, the related specific gas and liquid phase holdup profiles have been evaluated.

  16. Evaluation of pumping induced flow in observation wells during aquifer testing.

    Science.gov (United States)

    Székely, Ferenc

    2013-01-01

    The vertical variation of drawdown around pumping wells generates an induced flow in the observation wells. A set of governing equations is presented to couple the drawdown variation and the vertical flux distribution in observation wells. A numerical example is performed to justify the governing equations and to verify the solution methods used by the simulation software WT. The example analyzes the effect of skin loss, wellbore storage, and vertical segmentation on the drawdown and induced flow in observation well during pumping. The evaluation of the Fairborn pumping test involves a vertically homogeneous and anisotropic water table aquifer, uniform well-face drawdown conditions in the pumping well and simulation of the drawdown evolution in the observation well with and without the effect of induced flow. The computer calibrations resulted in small differences between the measured and simulated drawdown curves.

  17. Noninvasive miniaturized mass-flow meter using a curved cannula for implantable axial flow blood pump.

    Science.gov (United States)

    Kosaka, Ryo; Nishida, Masahiro; Maruyama, Osamu; Yamane, Takashi

    2011-01-01

    Blood flow should be measured to monitor conditions of patients with implantable artificial hearts continuously and noninvasively. We have developed a noninvasive miniaturized mass-flow meter using a curved cannula for an axial flow blood pump. The mass-flow meter utilized centrifugal force generated by the mass-flow rate in the curved cannula. Two strain gauges served as sensors. Based on the numerical analysis, the first gauge, attached to the curved area, measured static pressure and centrifugal force, and the second, attached to the straight area, measured static pressure for static pressure compensation. The mass-flow rate was determined by the differences in output from the two gauges. To compensate for the inertia force under the pulsatile flow, a 0.75-Hz low-pass filter was added to the electrical circuit. In the evaluation tests, numerical analysis and an actual measurement test using bovine blood were performed to evaluate the measurement performances. As a result, in the numerical analysis, the relationship between the differential pressure caused by centrifugal force and the flow rate was verified. In the actual measurement test, measurement error was less than ± 0.5 L/min, and the time delay was 0.12 s. We confirmed that the developed mass-flow meter was able to measure mass-flow rate continuously and noninvasively.

  18. Numerical Analysis of Rotating Pumping Flows in Inter-Coil Rotor Cavities and Short Cooling Grooves of a Generator

    Directory of Open Access Journals (Sweden)

    Wei Tong

    2001-01-01

    Full Text Available An important characteristic of wall rotating-driven flows is the tendency of fluid with high angular momentum to be flung radially outward. For a generator, the rotor rotating-driven flow, usually referred to as the rotating pumping flow, plays an important role in rotor winding cooling. In this study, three-dimensional numerical analyzes are presented for turbulent pumping flow in the inter-coil rotor cavity and short cooling grooves of a generator. Calculations of the flow field and the mass flux distribution through the grooves were carried out in a sequence of four related cases Under an isothermal condition: (a pumping flow, which is the self-generated flow resulted from the rotor pumping action; (b mixing flow, which is the combination of the ventilating flow and pumping flow, under a constant density condition; (c mixing flow, with density modeled by the ideal gas law; and (d mixing flow, with different pressure differentials applied on the system. The comparisons of the results from these cases can provide useful information regarding the impacts of the ventilating flow, gas density, and system pressure differential on the mass flux distribution in the short cooling grooves. Results show that the pumping effect is strong enough to generate the cooling flow for rotor winding cooling. Therefore, for small- or mid-size generators ventilation fans may be eliminated. It also suggests that increasing the chimney dimension can improve the distribution uniformity of mass flux through the cooling grooves.

  19. Flow in air conditioned rooms

    DEFF Research Database (Denmark)

    Nielsen, Peter V.

    1974-01-01

    Flow in air conditioned r ooms is examined by means of model experiments . The different gearnetries giving unsteady, steady three- dimensional and steady twodimensional flow are determined . Velacity profiles and temperature profiles are measured in some of the geometries. A numerical solution...... of the flow equations is demonstrated and the flow in air conditioned rooms in case of steady two dimensional flow is predi cted. Compari son with measured results is shown i n the case of small Archimedes numbers, and predictions are shown at high Archimedes numbers. A numerical prediction of f low and heat...

  20. Increase of economy of torque flow pump with high specific speed

    Science.gov (United States)

    Gusak, A. G.; Krishtop, I. V.; German, V. F.; Baga, V. N.

    2017-08-01

    Torque flow pumps are widely spread types of energy machines, which are used in majority of modern branches of industry for pumping of dirty media. The main task of researchers of torque flow pumps is increase of such pumps effectiveness for higher feed. Hydraulic losses for torque flow pumps are caused by working process of such pumps and are inevitable. Decrease of losses can be obtained by means of optimization of hydraulic flow part geometry. Modern approach to design of pump outlet introduces new constructive solutions which can increase economy of torque flow pumps. The aim of this research is increase of economy of torque flow pumps by means of application of spatial outlet and investigation of its geometry on pump characteristics. Analytical and numerical methods of liquid flow research for hydraulic flow part of torque flow pump were used in this paper. Moreover, influence of hydraulic flow part geometry of different designs of “Turo” type torque flow pumps outlets on pump characteristics was investigated. Numerical research enabled to study process of energy transfer of torque flow pump and evaluate influence of geometrical dimensions of spatial spiral outlet on its characteristics. Besides numerical research confirmed introduced regularity of peripheral velocity distribution in outlet. Velocity moment distribution in outlet was obtained during implementation of numerical research. Implemented bench tests of torque flow pump prototypes enabled to obtain real characteristics of pump and confirm effectiveness of spatial geometry of outlet application for such pump.

  1. Cavitation and two-phase flow characteristics of SRPR (Savannah River Plant Reactor) pump. Final report

    Energy Technology Data Exchange (ETDEWEB)

    1991-07-01

    The possible head degradation of the SRPR pumps may be attributable to two independent phenomena, one due to the inception of cavitation and the other due to the two-phase flow phenomena. The head degradation due to the appearance of cavitation on the pump blade is hardly likely in the conventional pressurized water reactor (PWR) since the coolant circulating line is highly pressurized so that the cavitation is difficult to occur even at LOCA (loss of coolant accident) conditions. On the other hand, the suction pressure of SRPR pump is order-of-magnitude smaller than that of PWR so that the cavitation phenomena, may prevail, should LOCA occur, depending on the extent of LOCA condition. In this study, therefore, both cavitation phenomena and two-phase flow phenomena were investigated for the SRPR pump by using various analytical tools and the numerical results are presented herein.

  2. 3-dimensional Simulation of an Air-lift Pump from Bubbly to Slug Flow

    Energy Technology Data Exchange (ETDEWEB)

    Jo, Hongrae; Jo, Daeseong [Kyungpook National Univ, Daegu (Korea, Republic of)

    2015-10-15

    The air-lift pump has been used in various applications with its merit that it can pump up without any moving parts. E.g. coffee percolator, petroleum industry, suction dredge, OTEC i.e. ocean thermal energy conversion and so on. By the merit, it has high durability for high temperature water or vapor, and fluid-solid mixture like waste water, muddy water and crude, which cause problems when it's pumped up with general pumps. In this regard, the air-lift pump has been one of the most desirable technology. A typical air-lift pump configuration is illustrated in Figure 01. The principle of this pump is very simple. When air is injected from the injector at bottom of a submerged tube, i.e., air bubbles are suspended in the liquid, the average density of the mixture in the tube is less than that of the surrounding fluid in the reservoir. Then hydrostatic pressure over the length of the tube is decreased. This buoyancy force causes a pumping action. The comparison of the simulated results, experimental result, and theoretical result is been able by data shown as Figure 04. They have similar trends but they also have a little differences because there are some limits of simulating the flow regimes. At the different flow condition, different coefficients for friction factor or pressure drop should be used, but this simulation uses a laminar condition and the theoretical equations are valid only for slug regime where the air flow rate is lower than the other regimes. From these causes, the differences has arisen, and difference comes bigger as the air flow rate increases, i.e., becoming annular flow regime or churn flow regime.

  3. 微极流体蠕动泵经由滑移边界管道输送的Stokes流动%Study on Stokes Flow of Micro-Polar Fluids by Peristaltic Pumping Through a Tube With Slip Boundary Condition

    Institute of Scientific and Technical Information of China (English)

    D·特里帕蒂; M·K·乔伯; P·K·古泊塔; 吴承平

    2011-01-01

    The Stokes flow of micro-polar fluids by peristaltic pumping through the cylindrical tube under the effect of slip boundary condition was studied. The motion of wall was governed by the sinusoidal wave equation. Analytical and numerical solutions for axial velocity, micro-polar vector, stream function, pressure gradient, friction force and mechanical efficiency were obtained by using the lubrication theory. The impacts of emerging parameters such as coupling number, micro-polar parameter and slip parameter on pumping characteristic, friction force and trapping phenomena were depicted graphically. Numerical computation infers that more pressure requires for peristaltic pumping when coupling number is large while opposite behavior is found for micro-polar parameter and the slip parameter. The size of trapped bolus reduces with coupling number and micro-polar parameter whereas it blows up with slip parameter.%计及管道边界条件滑移的影响,研究微极流体蠕动泵,经由圆柱形管道输运的Stokes流动.壁面运动的控制方程为正弦波方程.使用润滑理论,得到了轴向速度、微转动向量、流函数、压力梯度、摩擦力和机械效率的解析数值解.用图形表示出构成参数,如像耦合参数、微极参数和表征蠕流泵特性的滑移参数、摩擦力和俘获现象的影响.数值计算表明,当耦合参数较大时,需要蠕动泵的压力更大,而微极参数和滑移参数正相反.俘获团块的大小随耦合参数和微极参数的减小而缩小,而随滑移参数的增大而缩小.

  4. Axial and centrifugal continuous-flow rotary pumps: a translation from pump mechanics to clinical practice.

    Science.gov (United States)

    Moazami, Nader; Fukamachi, Kiyotaka; Kobayashi, Mariko; Smedira, Nicholas G; Hoercher, Katherine J; Massiello, Alex; Lee, Sangjin; Horvath, David J; Starling, Randall C

    2013-01-01

    The recent success of continuous-flow circulatory support devices has led to the growing acceptance of these devices as a viable therapeutic option for end-stage heart failure patients who are not responsive to current pharmacologic and electrophysiologic therapies. This article defines and clarifies the major classification of these pumps as axial or centrifugal continuous-flow devices by discussing the difference in their inherent mechanics and describing how these features translate clinically to pump selection and patient management issues. Axial vs centrifugal pump and bearing design, theory of operation, hydrodynamic performance, and current vs flow relationships are discussed. A review of axial vs centrifugal physiology, pre-load and after-load sensitivity, flow pulsatility, and issues related to automatic physiologic control and suction prevention algorithms is offered. Reliability and biocompatibility of the two types of pumps are reviewed from the perspectives of mechanical wear, implant life, hemolysis, and pump deposition. Finally, a glimpse into the future of continuous-flow technologies is presented.

  5. Flow Structure Around the Intake of a Vertical Pump

    Institute of Scientific and Technical Information of China (English)

    Akihiro WADA

    2006-01-01

    The flow structure around the intake of a vertical pump is investigated experimentally and numerically in order to obtain a guideline in designing the optimum shape of the intake of vertical pumps, in which their installation area is demanded to be minimum without losing the high performance. We concentrate our attention on the expansion ratio of the intake as a representative characteristic of the shape of the pumps and investigate the effect of the expansion ratio on pump performance. It is concluded that the optimum expansion ratio ranges in 1.1~1.2 if we take into consideration that the area needed for the installation of the pump should be minimum.

  6. Investigation of the Flow Field and Performances of a Centrifugal Pump at Part Load

    Science.gov (United States)

    Prunières, R.; Inoue, Y.; Nagahara, T.

    2016-11-01

    Centrifugal pump performance curve instability, characterized by a local dent at part load, can be the consequence of flow instabilities in rotating or stationary parts. Such flow instabilities often result in abnormal operating conditions which can damage both the pump and the system. In order for the pump to have reliable operation over a wide flow rate range, it is necessary to achieve a design free of instability. The present paper focuses on performance curve instability of a centrifugal pump of mid specific speed (ωs = 0.65) for which instability was observed at part load during tests. The geometry used for this research consist of the first stage of a multi-stage centrifugal pump and is composed of a suction bend, a closed-type impeller, a vaned diffuser and return guide vanes. In order to analyse the instability phenomenon, PIV and CFD analysis were performed. Both methods qualitatively agree relatively well. It appears that the main difference before and after head drop is an increase of reverse flow rate at the diffuser passage inlet on the hub side. This reverse flow decreases the flow passing area at the diffuser passage inlet, disallowing effective flow deceleration and impairing static pressure recovery.

  7. Optimization of Meridional Flow Channel Design of Pump Impeller

    OpenAIRE

    Miyauchi Sunao; Horiguchi Hironori; Fukutomi Jun-ichirou; Takahashi Akihiro

    2004-01-01

    The meridional flow channel design of a pump impeller affects its performance. However, since so many design parameters exist, a new design method is proposed in which a meridional and blade-to-blade flow channel is designed by the parallel use of the circulation distribution provided by the designer. Thus, an optimization method was used to design an axis-symmetrical meridional flow channel from the circulation distribution. In addition, the inverse design method proposed by Zangeneh et al. ...

  8. Analysis of the performances of an axial flow tandem pump based on CFD computations

    Science.gov (United States)

    Zhao, Y.; Bai, Z. Y.; Zhang, M. D.; Wang, G. Y.

    2012-11-01

    Tandem pump, compared with multistage pump, goes without guide vanes between impellers. Significant reduction of the axial geometry scale, resulting from lack of guide vanes, makes great sense to high-speed propulsion. Direct interactions between front and rear impellers may lead to special flows, which are different from those in a multistage pump. There are few studies of these differences. In this article, CFD computations of flows in an axial flow tandem pump are conducted to predict the performances. FBM turbulence model, which is introduced to commercial software, is used for the simulations. Circulation coefficient is defined to help analyze energy characteristics. The results demonstrate that power of the tandem pump increases slowly as discharge is getting larger. The tandem pump has better adaptability under large discharge conditions. The head of the rear impeller is not sensitive to discharge's change, which results from that the front impeller weakens the influence of discharge's change on the rear impeller, so pump's energy characteristics may be improved.

  9. Condition monitoring, diagnostic and controlling tool for boiler feed pump

    Energy Technology Data Exchange (ETDEWEB)

    Ahmed, Sohail [Siemens AG, Muelheim (Germany). Energy Sector; Leithner, Reinhard; Kosyna, Guenter [TU Braunschweig (Germany)

    2010-07-01

    The boiler feed pump is an important component of a thermal power generation cycle and demands high safety and unquestionable availability for flexible power plant operation. In this research paper, the methodology of a general purpose condition monitoring, diagnostic and controlling tool is presented, which can address the challenges of operational safety and availability as well as optimal operation of a boiler feed pump. This tool not only effectively records the life time consumption of both casings and rotors and monitors the small gaps between casings and rotors but also suggests appropriate actions in order to ensure that the pump operates within the allowable design limits. (orig.)

  10. Investigation of the 4-Quadrant behaviour of a mixed flow diffuser pump with CFD-methods and test rig evaluation

    Science.gov (United States)

    Höller, S.; Benigni, H.; Jaberg, H.

    2016-11-01

    The complete pump characteristics including its 4-quadrant behaviour are of essential interest for off-design operations such as a pump trip. At this exceptional load case the pump enters the dissipation mode and moves further into the turbine mode while the direction of rotation and the flow direction will change. The time-consuming and expensive experimental investigation of the 4-quadrant behaviour requires a specific test rig, allowing the flow direction as well as the rotational direction of the investigated pump to be reverted. By measuring the pump performance (head and efficiency) at variable positive and negative discharge and rotation the complete pump characteristics are evaluated. Nowadays CFD- analysis allows for the reliable prediction of the hydraulic performance of a pump near the design point. However, abnormal operating conditions lead to complex and unsteady flow phenomena inside the pump. Besides steady-state calculations in the normal operating conditions quite comprehensive transient CFD-investigations are required to simulate the whole pump characteristics accurately. The present study focuses on the comparison of the results obtained on the test rig and by numerical methods and shows a remarkably good agreement between them. It can be shown that it is possible to reliably simulate the 4-quadrant behaviour of a mixed flow diffuser pump based on CFD-methods. Furthermore an exemplary waterhammer calculation shows the successful application of the numerically calculated 4- quadrant behaviour.

  11. RESEARCH OF INNER FLOW IN A DOUBLE BLADES PUMP BASED ON OPENFOAM

    Institute of Scientific and Technical Information of China (English)

    LIU Hou-lin; REN Yun; WANG Kai; WU Deng-hao; RU Wei-min; TAN Ming-gao

    2012-01-01

    The inner flow analysis of centrifugal pumps has gradually become an important issue for the hydraulic design and performance improvement.Nowadays,CFD simulation toolbox of pump inner flow mainly contains commercial tools and open source tools.There are some detects for commercial CFD software for the numerical simulation of 3-D turbulent internal flow in pump,especially in capturing the flow characteristics under the off-design operating conditions.Additionally,it is difficult for researchers to do further investigation because of the undeclared source.Therefore,an open source software like Open Field Operation and Manipulation (OpenFOAM) is increasingly popular with researchers from all over the world.In this paper,a new computational study was implemented based on the original solver and was used to directly simulate the steady-state inner flow in a double blades pump,with the specific speed is 111.In order to disclose the characteristics deeply,three research schemes were conducted.The ratios (Q/Qd) of the flow rate are 0.8,1.0 and 1.2,respectively.The simulation results were verified with the Particle Imaging Velocimetry (PIV) experimental results,and the numerical calculation results agree well with the experimental data.Meanwhile,the phenomena of flow separation under the off-design operating conditions are well captured by OpenFOAM.The results indicate that OpenFOAM possesses obvious strong predominance in computing the internal flow field of pump.The analysis results can also be used as the basis for the further research and the improvement of centrifugal pump.

  12. Effect of suction pipe leaning angle and water level on the internal flow of pump sump

    Science.gov (United States)

    Chen, Z.-M.; Lee, Y.-B.; Kim, K.-Y.; Park, S.-H.; Choi, Y.-D.

    2016-11-01

    The pump sump, which connects forebay and intake of pump station, supplies good flow condition for the intake of the pump. If suction sumps are improperly shaped or sized, air entraining vortices or submerged vortices may develop. This may greatly affect pump operation if vortices grow to an appreciable extent. Moreover, the noise and vibration of the pump can be increased by the remaining of vortices in the pump flow passage. Therefore, the vortices in the pump flow passage have to be reduced for a good performance of pump sump station. In this study, the effect of suction pipe leaning angle on the pump sump internal flow with different water level has been investigated by CFD analysis. Moreover, an elbow type pipe was also investigated. There are 3 leaning angles with 0°, 45° and 90° for the suction pipe. The suction pipe inlet centre is kept same for all the cases. In addition, the three different water levels of H/D=1.85, 1.54, and 1.31, is applied to different suction pipe types. The result shows that the amount of air sucked into the suction pipe increases with increasing the suction pipe leaning angle. Especially for the horizontal suction pipe, there is maximum air sucked into the suction pipe. However, there is certain effect of the elbow type bell mouth installation in the horizontal suction pipe on suppressing the amount of air sucked into the pipe. Moreover, vertical suction pipe plays an effective role on reducing the free surface vortex intake area.

  13. Noninvasive pulsatile flow estimation for an implantable rotary blood pump.

    Science.gov (United States)

    Karantonis, Dean M; Cloherty, Shaun L; Mason, David G; Ayre, Peter J; Lovell, Nigel H

    2007-01-01

    A noninvasive approach to the task of pulsatile flow estimation in an implantable rotary blood pump (iRBP) has been proposed. Employing six fluid solutions representing a range of viscosities equivalent to 20-50% blood hematocrit (HCT), pulsatile flow data was acquired from an in vitro mock circulatory loop. The entire operating range of the pump was examined, including flows from -2 to 12 L/min. Taking the pump feedback signals of speed and power, together with the HCT level, as input parameters, several flow estimate models were developed via system identification methods. Three autoregressive with exogenous input (ARX) model structures were evaluated: structures I and II used the input parameters directly; structure II incorporated additional terms for HCT; and the third structure employed as input a non-pulsatile flow estimate equation. Optimal model orders were determined, and the associated models yielded minimum mean flow errors of 5.49% and 0.258 L/min for structure II, and 5.77% and 0.270 L/min for structure III, when validated on unseen data. The models developed in this study present a practical method of accurately estimating iRBP flow in a pulsatile environment.

  14. Internal flow numerical simulation of double-suction centrifugal pump using DES model

    Science.gov (United States)

    Zhou, P. J.; Wang, F. J.; Yang, M.

    2012-11-01

    It is a challenging task for the flow simulation for a double-suction centrifugal pump, because the wall effects are strong in this type of pumps. Detached-eddy simulation (DES), referred as a hybrid RANS-LES approach, has emerged recently as a potential compromise between RANS based turbulence models and Large Eddy Simulation. In this approach, the unsteady RANS model is employed in the boundary layer, while the LES treatment is applied to the separated region. In this paper, S-A DES method and SST k-ω DES method are applied to the numerical simulation for the 3D flow in whole passage of a double-suction centrifugal pump. The unsteady flow field including velocity and pressure distributions is obtained. The head and efficiency of the pump are predicted and compared with experimental results. According to the calculated results, S-A DES model is easy to control the partition of the simulation when using near wall grid with 30 suction centrifugal pump. S-A DES method can capture more flow phenomenon than SST k - ω DES method. In addition, it can accurately predict the power performance under different flow conditions, and can reflect pressure fluctuation characteristics.

  15. Study of flow instability in off design operation of a multistage centrifugal pump

    Energy Technology Data Exchange (ETDEWEB)

    Shibata, Akiha; Maeda, Manabu; Kamei, Shun; Hazama, Ryota; Sano, Takeshi; Iino, Masamichi [Mitsubishi Heavy Industries, Ltd., Tokyo (Japan); Hiramatsu, Hideto; Komaki, Shutaro; Miyagawa, Kazuyoshi [Waseda University, Okubo (Japan)

    2016-02-15

    In recent years, attempts have been made to make multistage centrifugal pumps smaller in size and more efficient. However, such designs are known to cause positive-slope phenomena in the Q-H curve, especially under low-flow conditions. These phenomena, which have thus far been studied experimentally and numerically, stem from flow instability in the pump. However, their mechanisms have not yet been clarified because it depends on various parameters. In this study, we focused on diffuser rotating stall, observed in positive Q-H characteristics. This study elucidates the mechanism of positive-slope generation through experimental results and two-dimensional numerical analysis.

  16. Quantitative Analysis of Groundwater Flow near a Partially Penetrating River under Riverside Pumping

    Institute of Scientific and Technical Information of China (English)

    WANG Bingchen; ZHENG Xilai; QIAN Hui; LIN Guoqing; XU Qiant

    2004-01-01

    According to practical geological and hydrogeological conditions of riverside water-supply well fields in northwestern China, an ideal hydrogeological model has been generalized and a three-dimensional mathematical model has been set up. A finite difference method was applied to simulating groundwater flow near a partially penetrating river under riverside pumping, and to analyzing the effects of river width, partial penetration and permeability of riverbed sediments on groundwater recharges. Results show that riverside pumping may cause groundwater to flow beneath the partially penetrating river, and that river width, penetration and riverbed permeability obviously influence flows from the partially penetrating river and constant-head boundaries. However, the pumping output is mainly from the partially penetrating river.

  17. PUMPS

    Science.gov (United States)

    Thornton, J.D.

    1959-03-24

    A pump is described for conveving liquids, particure it is not advisable he apparatus. The to be submerged in the liquid to be pumped, a conduit extending from the high-velocity nozzle of the injector,and means for applying a pulsating prcesure to the surface of the liquid in the conduit, whereby the surface oscillates between positions in the conduit. During the positive half- cycle of an applied pulse liquid is forced through the high velocity nozzle or jet of the injector and operates in the manner of the well known water injector and pumps liquid from the main intake to the outlet of the injector. During the negative half-cycle of the pulse liquid flows in reverse through the jet but no reverse pumping action takes place.

  18. Characterization and reduction of flow separation in jet pumps for laminar oscillatory flows

    CERN Document Server

    Timmer, Michael A G; Bühler, Simon; Wilcox, Douglas; van der Meer, Theo H

    2016-01-01

    A computational fluid dynamics model is used to predict the oscillatory flow through tapered cylindrical tube sections (jet pumps). The asymmetric shape of jet pumps results in a time-averaged pressure drop that can be used to suppress Gedeon streaming in closed-loop thermoacoustic devices. However, previous work has shown that flow separation in the diverging flow direction counteracts the time-averaged pressure drop. In this work, the characteristics of flow separation in jet pumps are identified and coupled with the observed jet pump performance. Furthermore, it is shown that the onset of flow separation can be shifted to larger displacement amplitudes by designs that have a smoother transition between the small opening and the tapered surface of the jet pump. These design alterations also reduce the duration of separated flow, resulting in more effective and robust jet pumps. To make the proposed jet pump designs more compact without reducing their performance, the minimum big opening radius that can be i...

  19. Condition monitoring of pump-turbines

    OpenAIRE

    Valero Ferrando, M.del Carmen; Egusquiza Estévez, Eduard

    2014-01-01

    At present, new renewables like wind, solar and marine energy are having a strong development. The generation of energy by renewables has the disadvantage that it depends on atmospheric conditions. It means that they can generate energy at any moment independently if this energy is required or not by the consumers. For the stability of the electrical grid, supply and demand of energy has to be matched. The surplus of energy produced when consumption is low has to be stored and del...

  20. Water Flow Testing and Unsteady Pressure Analysis of a Two-Bladed Liquid Oxidizer Pump Inducer

    Science.gov (United States)

    Schwarz, Jordan B.; Mulder, Andrew; Zoladz, Thomas

    2011-01-01

    The unsteady fluid dynamic performance of a cavitating two-bladed oxidizer turbopump inducer was characterized through sub-scale water flow testing. While testing a novel inlet duct design that included a cavitation suppression groove, unusual high-frequency pressure oscillations were observed. With potential implications for inducer blade loads, these high-frequency components were analyzed extensively in order to understand their origins and impacts to blade loading. Water flow testing provides a technique to determine pump performance without the costs and hazards associated with handling cryogenic propellants. Water has a similar density and Reynolds number to liquid oxygen. In a 70%-scale water flow test, the inducer-only pump performance was evaluated. Over a range of flow rates, the pump inlet pressure was gradually reduced, causing the flow to cavitate near the pump inducer. A nominal, smooth inducer inlet was tested, followed by an inlet duct with a circumferential groove designed to suppress cavitation. A subsequent 52%-scale water flow test in another facility evaluated the combined inducer-impeller pump performance. With the nominal inlet design, the inducer showed traditional cavitation and surge characteristics. Significant bearing loads were created by large side loads on the inducer during synchronous cavitation. The grooved inlet successfully mitigated these loads by greatly reducing synchronous cavitation, however high-frequency pressure oscillations were observed over a range of frequencies. Analytical signal processing techniques showed these oscillations to be created by a rotating, multi-celled train of pressure pulses, and subsequent CFD analysis suggested that such pulses could be created by the interaction of rotating inducer blades with fluid trapped in a cavitation suppression groove. Despite their relatively low amplitude, these high-frequency pressure oscillations posed a design concern due to their sensitivity to flow conditions and

  1. Numerical investigation of cavitation-vortex interaction in a mixed-flow water jet pump

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Renfang; Lou, Xianwu [Tsinghua University, Beijing (China); Ji, Bin [Wuhan University, Hubei (China); Zhai, Zhihong; Zhou, Jiajian [Marine Design and Research Institute of China, Shanghai (China)

    2015-09-15

    Turbulent cavitating flows in a mixed-flow waterjet pump were numerically investigated using the k-w SST turbulence model and the mass transfer cavitation model based on the Rayleigh-Plesset equation to provide a comprehensive understanding of the cavitation-vortex interaction mechanism. The predicted hydraulic performance, as well as the cavitation performance, exhibits a reasonable agreement with the experimental results. The vorticity distributions under three operation conditions were illustrated together. Based on the illustration, cavitation development enhances vorticity production and flow unsteadiness in a mixed-flow waterjet pump. Vortices are basically located at the cavity interface, particularly at the downstream interface, during cavitation. Further analyses using the relative vorticity transport equation in cavitating turbulent flows indicate that vortex dilation and baroclinic torque exhibit a steep jump as cavitation occurs. In addition, vortex stretching contributes mainly to large-scale vortex generation.

  2. Unsteady fluid flow in smart material actuated fluid pumps

    Science.gov (United States)

    John, Shaju; Cadou, Christopher

    2005-05-01

    Smart materials' ability to deliver large block forces in a small package while operating at high frequencies makes them extremely attractive for converting electrical to mechanical power. This has led to the development of hybrid actuators consisting of co-located smart material actuated pumps and hydraulic cylinders that are connected by a set of fast-acting valves. The overall success of the hybrid concept hinges on the effectiveness of the coupling between the smart material and the fluid. This, in turn, is strongly dependent on the resistance to fluid flow in the device. This paper presents results from three-dimensional unsteady simulations of fluid flow in the pumping chamber of a prototype hybrid actuator powered by a piezo-electric stack. The results show that the forces associated with moving the fluid into and out of the pumping chamber already exceed 10% of the piezo stack blocked force at relatively low frequencies ~120 Hz and approach 40% of the blocked force at 800 Hz. This reduces the amplitude of the piston motion in such a way that the volume flow rate remains approximately constant above operating frequencies of 500 Hz while the efficiency of the pump decreases rapidly.

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

    Science.gov (United States)

    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.

  4. Dynamic Characteristics of Rotating Stall in Mixed Flow Pump

    Directory of Open Access Journals (Sweden)

    Xiaojun Li

    2013-01-01

    Full Text Available Rotating stall, a phenomenon that causes flow instabilities and pressure hysteresis by propagating at some fraction of the impeller rotational speed, can occur in centrifugal impellers, mixed impellers, radial diffusers, or axial diffusers. Despite considerable efforts devoted to the study of rotating stall in pumps, the mechanics of this phenomenon are not sufficiently understood. The propagation mechanism and onset of rotating stall are not only affected by inlet flow but also by outlet flow as well as the pressure gradient in the flow passage. As such, the complexity of these concepts is not covered by the classical explanation. To bridge this research gap, the current study investigated prerotation generated at the upstream of the impeller, leakage flow at the tip clearance between the casing and the impeller, and strong reserve flow at the inlet of the diffuser. Understanding these areas will clarify the origin of the positive slope of the head-flow performance curve for a mixed flow pump. Nonuniform pressure distribution and adverse pressure gradient were also introduced to evaluate the onset and development of rotating stall within the diffuser.

  5. Quasi-three dimensional hydraulic design and performance calculation of high specific speed mixed-flow pump

    Science.gov (United States)

    Su, M.; Zhang, Y. X.; Zhang, J. Y.; Hou, H. C.

    2016-05-01

    According to the basic parameters of 211-80 high specific speed mixed-flow pump, based on the quasi-three dimensional flow theory, the hydraulic design of impeller and its matching spaced guide vanes for high specific speed mixed flow pump was completed, in which the iterative calculation of S 1, S 2 stream surfaces was employed to obtain meridional flow fields and the point-by-point integration method was employed to draw blade camber lines. Blades are thickened as well as blade leading edges are smoothed in the conformal mapping surface. Subsequently the internal fields of the whole flow passage of the designed pump were simulated by using RANS equations with RNG k-ε two-equation turbulent model. The results show that, compared with the 211-80 model, the hydraulic efficiency of the designed pump at the optimal flow rate increases 9.1%. The hydraulic efficiency of designed pump in low flow rate condition (78% designed flow rate) increases 6.46%. The hydraulic efficiency in high flow rate areas increases obviously and there is no bad phenomenon of suddenly decrease of hydraulic efficiency in model pump. From the distributions of velocity and pressure fields, it can be seen that the flow in impeller is uniform and the increase of pressure is gentle. There are no obvious impact phenomenon on impeller inlet and obvious wake shedding vortex phenomenon from impeller outlet to guide vanes inlet.

  6. The high Reynolds number flow through an axial-flow pump

    Science.gov (United States)

    Zierke, W. C.; Straka, W. A.; Taylor, P. D.

    1993-11-01

    The high Reynolds number pump (HIREP) facility at ARL Penn State has been used to perform a low-speed, large-scale experiment of the incompressible flow of water through a two-blade-row turbomachine. HIREP can involve blade chord Reynolds numbers as high as 6,000,000 and can accommodate a variety of instrumentation in both a stationary and a rotating frame of reference. The objectives of this experiment were as follows: to provide a database for comparison with three-dimensional, viscous (turbulent) flow computations; to evaluate the engineering models; and to improve our physical understanding of many of the phenomena involved in this complex flow field. The experimental results include a large quantity of data acquired throughout HIREP. A five-hole probe survey of the inlet flow 37.0 percent chord upstream of the inlet guide vane (IGV) leading edge is sufficient to give information for the inflow boundary conditions, while some static-pressure information is available to help establish an outflow boundary condition.

  7. NUMERICAL INVESTIGATION OF FLOW PATTERNS IN DIFFERENT PUMP INTAKE SYSTEMS

    Institute of Scientific and Technical Information of China (English)

    ZHAN Jie-min; WANG Ben-cheng; YU Ling-hui; LI Yok-sheung; TANG Ling

    2012-01-01

    A 3-D numerical model for pump intake is established based on the Navier-Stokes equations with the RNG k-εturbulence model and the VOF method to simulate the free surface.The applicability of the proposed model is validated by a test case of non-symmetric pump-intake bay.The predicted locations,structures and shapes of all vortices are in good agreement with those observed in experiments,though with some differences in vorticity strengths.The flow pattern and the efficiency of five types of pump intake systems are studied.The discharge and the velocity uniformity of the intake system are used as indices to evaluate its performance.

  8. Cavitation study of a pump-turbine at turbine mode with critical cavitation coefficient condition

    Science.gov (United States)

    Wang, J.; Yang, D.; Xu, J. W.; Liu, J. T.; Jiao, L.

    2016-05-01

    To study the cavitation phenomenon of a pump-turbine at turbine mode when it ran at the critical cavitation coefficient condition, a high-head model pump-turbine was disperse using hexahedron grid. Three dimensional, steady cavitating flow was numerically studied using SST k-ω model. It is confirmed that ZGB cavitation model and SST k-ω model are useful ways to study the two-phase cavitation flow in pump-turbine. Mass flow inlet and pressure outlet were specified at the casing inlet and draft tube outlet, respectively. The static pressure was set according to the cavitation coefficient. The steady cavitating flows at critical cavitation coefficient condition were analysed. The cavitation area in the runner was investigated. It was found that the pressure of the suction on the blade surface was decreasing gradually with the decrease of the cavitation coefficient. In addition, the vortex flow in the draft tube was observed at the critical cavitation coefficient. It was found that the vortex flow appeared at the center of the draft tube inlet with the decreasing of the cavitation coefficient. Compared with the experimental data, the simulation results show reasonable agreement with the experimental data.

  9. CFD Numerical Simulation of the Complex Turbulent Flow Field in an Axial-Flow Water Pump

    Directory of Open Access Journals (Sweden)

    Wan-You Li

    2014-09-01

    Full Text Available Further optimal design of an axial-flow water pump calls for a thorough recognition of the characteristics of the complex turbulent flow field in the pump, which is however extremely difficult to be measured using the up-to-date experimental techniques. In this study, a numerical simulation procedure based on computational fluid dynamics (CFD was elaborated in order to obtain the fully three-dimensional unsteady turbulent flow field in an axial-flow water pump. The shear stress transport (SST k-ω model was employed in the CFD calculation to study the unsteady internal flow of the axial-flow pump. Upon the numerical simulation results, the characteristics of the velocity field and pressure field inside the impeller region were discussed in detail. The established model procedure in this study may provide guidance to the numerical simulations of turbomachines during the design phase or the investigation of flow and pressure field characteristics and performance. The presented information can be of reference value in further optimal design of the axial-flow pump.

  10. Reactor coolant pump shaft seal behavior during blackout conditions

    Energy Technology Data Exchange (ETDEWEB)

    Mings, W.J.

    1985-01-01

    The United States Nuclear Regulatory Commission has classified the problem of reactor coolant pump seal failures as an unresolved safety issue. This decision was made in large part due to experimental results obtained from a research program developed to study shaft seal performance during station blackout and reported in this paper. Testing and analysis indicated a potential for pump seal failure under postulated blackout conditions leading to a loss of primary coolant with a concomitant danger of core uncovery. The work to date has not answered all the concerns regarding shaft seal failure but it has helped scope the problem and focus future research needed to completely resolve this issue.

  11. Conditioning geostatistical simulations of a bedrock fluvial aquifer using single well pumping tests

    Science.gov (United States)

    Niazi, A.; Bentley, L. R.; Hayashi, M.

    2015-12-01

    Geostatistical simulation is a powerful tool to explore the uncertainty associated with heterogeneity in groundwater and reservoir studies. Nonetheless, conditioning simulations merely with lithological information does not utilize all of the available information and so some workers additionally condition simulations with flow data. In this study, we introduce an approach to condition geostatistical simulations of the Paskapoo Formation, which is a paleo-fluvial system consisting of sandstone channels embedded in mudstone. The conditioning data consist of two-hour single well pumping tests extracted from the public water well database in Alberta, Canada. In this approach, lithologic models of an entire watershed are simulated and conditioned with hard lithological data using transition probability geostatistics (TPROGS). Then, a segment of the simulation around a pumping well was used to populate a flow model (FEFLOW) with either sand or mudstone. The values of the hydraulic conductivity and specific storage of sand and mudstone were then adjusted to minimize the difference between simulated and actual pumping test data using the parameter estimation program PEST. If the simulated data do not adequately match the measured data, the lithologic model is updated by locally deforming the lithology distribution using the probability perturbation method (PPM) and the model parameters are again updated with PEST. This procedure is repeated until the simulated and measured data agree within a pre-determined tolerance. The procedure is repeated for each pumping well that has pumping test data. The method constrains the lithological simulations and provides estimates of hydraulic conductivity and specific storage that are consistent with the pumping test data. Eventually, the simulations will be combined in watershed scale groundwater models.

  12. Off-pump replacement of the INCOR implantable axial-flow pump.

    Science.gov (United States)

    Nakashima, Kuniki; Kirsch, Matthias E W; Vermes, Emmanuelle; Rosanval, Odile; Loisance, Daniel

    2009-02-01

    Owing to the actual increase of mechanical circulatory support durations, total or partial replacement of ventricular assist devices (VADs) will most certainly have to be performed with increasing frequency. Herein we report the case of a patient in whom an INCOR (Berlin Heart AG, Berlin) implantable axial-flow pump was replaced without the use of cardiopulmonary bypass (CPB), underscoring some of the unique features provided by this system.

  13. Experimental study of flow field in interference area between impeller and guide vane of axial flow pump

    Institute of Scientific and Technical Information of China (English)

    张华; 施卫东; 陈斌; 曹卫东; 张启华

    2014-01-01

    Axial flow pump is a kind of typical pumps with rotor-stator interaction, thus the measurement of the flow field between impeller and guide vane would facilitate the study of the internal rotor-stator interaction mechanism. Through a structural modifi-cation of a traditional axial flow pump, the requirements of particle image velocimetry (PIV) measurement are met. Under the condition of opt.0.8Q , the axial vortex is identified between impeller hub and guide vane hub, which is developed into the main flow and to affect the movement when the relative positions of impeller and guide vane at different flow rates are the same. Besides, the development and the dissipation of the tip leakage and the passage vortex in impeller passages are mainly responsible for the difference of the flow field close to the outer rim. As the flow rate decreases, the distribution of the meridional velocities at the impeller outlet becomes more non-uniform and the radial velocity component keeps increasing. The PIV measurement results under the condition of opt.1.0Q indicate that the flow separation and the trailing vortex at the trailing edge of a blade are likely to result in a velocity sudden change in this area, which would dramatically destroy the continuity of the flow field. Moreover, the radial direction of the flow between impeller and guide vane on the measurement plane does not always point from hub to rim. For a certain position, the direction is just from rim to hub, as is affected by the location of the intersection line of the shooting section and the impeller blade on the impeller as well as the angle between the intersection line and the rotating shaft.

  14. MHD interaction in an Electromagnetic Pump for high flow rate loop of ASTRID Sodium Fast Reactor secondary circuit, behavior

    OpenAIRE

    Letout, S; Duterrail, Y; Fautrelle, Y; Medina, M. , il.; Rey, F.; Laffont, G.

    2015-01-01

    International audience; The present paper deals with the analysis of the behaviour of a very large Annular Linear Induction Pumps (ALIP) for liquid sodium. This pump is able to provide high flow rates (more than 7,000 m3/h with a pressure discharge of about 3.7 bar). Dimensions of pumping channel under the active part are of an average diameter of 966 mm and a length of 4,500 mm. The global and local stability of the pump are analyzed. It is found that in the nominal conditions, stable operat...

  15. Pipe flow of pumping wet shotcrete based on lubrication layer.

    Science.gov (United States)

    Chen, Lianjun; Liu, Guoming; Cheng, Weimin; Pan, Gang

    2016-01-01

    Wet shotcrete can reduce dust and improve supporting strength, however, safe and efficient pipage is a key technical part of wet shotcrete process. The paper studied the pipe flow law of wet shotcrete based on lubrication layer by build the experimental pumping circuit of wet shotcrete that can carry out a number of full-scale pumping tests. The experimental results show there was a linear relationship between pressure loss and flow rate. Combined with the Buckingham rheological equation, the computing equations of the yield shear stress and plastic viscosity were deduced through linear regression. A simple analytical method allowing for a rough estimation of the pumping pressure was proposed and used when considering the lubrication layer of wet shotcrete in pipes. In addition, two kinds of particulate distributive models were established along the time axial to analyze the formation of lubrication layer which is related with particles migration. By computational fluid dynamics simulation, the lubrication layer thickness of different mix proportions was estimated. A new method for measuring the thickness of lubrication layer was proposed to verify it by binarization processing. Finally, according to the comparative analysis of experiments, simulation and computed value, it can be seen that the lubrication layer plays a key role in the process of wet shotcrete flow and with the increase of lubrication layer thickness pipe pressure declines gradually.

  16. Output speed and flow of double-acting double-stator multi-pumps and multi-motors

    Institute of Scientific and Technical Information of China (English)

    De-sheng WEN; Zhi-li WANG; Jun GAO; Yong ZHANG; Shi-jun LV; Tetsuhiro TSUKIJI

    2011-01-01

    The primary focus of this study was to investigate a series of novel motors and pumps, based on a new type of structure called double-stator. The double-stator structure can be used as pump or motor just based on the application requirements. A certain amount of pumps or motors can be formed in one shell, and these sub-pumps or sub-motors can work alone or be combined without influence on each other. So this kind of double-stator pump (motor) is called a multi-pump (multi-motor). Through the analysis of multifarious connection modes of the double-acting double-stator multi-pumps and multi-motors, the mathematical expressions of the output flow rate and the rotational speed are acquired. The results indicate that a quantity of different flow rates can be provided by one fixed-displacement multi-pump under the condition of unalterable driven speed by electromotor. Likewise,when supplied by settled input flow, without complex variable mechanism, the functions of double-speed, multiple-speed, and even differential connection can be obtained by employing the use of a double-stator multi-motor. The novel hydraulic transmission is made of such a double-stator multi-pump and multi-motor, and has broad application prospects.

  17. Numerical investigation on vibration and noise induced by unsteady flow in an axial-flow pump

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Eryun; Ma, Zui Ling; Yang, Ai Ling; Nan, Guo Fang [School of Energy and Power Engineering, University of Shanghai for Science and Technology, Shanghai (China); Zhao, Gai Ping [School of Medical Instruments and Food Engineering, University of Shanghai for Science and Technology, Shanghai (China); Li, Guo Ping [Shanghai Marine Equipment Research Institute, Shanghai (China)

    2016-12-15

    Full-scale structural vibration and noise induced by flow in an axial-flow pump was simulated by a hybrid numerical method. An unsteady flow field was solved by a large eddy simulation-based computational fluid dynamics commercial code, Fluent. An experimental validation on pressure fluctuations was performed to impose an appropriate vibration exciting source. The consistency between the computed results and experimental tests were interesting. The modes of the axial-flow pump were computed by the finite element method. After that, the pump vibration and sound field were solved using a coupled vibro-acoustic model. The numerical results indicated that the the blade-passing frequency was the dominant frequency of the vibration acceleration of the pump. This result was consistent with frequency spectral characteristics of unsteady pressure fluctuation. Finally, comparisons of the vibration acceleration between the computed results and the experimental test were conducted. These comparisons validated the computed results. This study shows that using the hybrid numerical method to evaluate the flow-induced vibration and noise generated in an axial-flow pump is feasible.

  18. Numerical simulation on rectifying flow in intake system of a pumping station connected with headrace pipe

    Science.gov (United States)

    Zi, D.; Wang, F. J.; Yao, Z. F.; Xiao, R. F.; Chen, X.; He, C. L.

    2016-11-01

    Pipes are usually adopted in those conditions for which the pump house is far from water source. As for fore-bay, flow of headrace pipe can be considered as jet-flow. Jet-flow has a high velocity, and creates large pressure gradient between jet-flow and near wall flow, which contributes to large scale circulation. In that circumstance, a single rectification measure cannot effectively improve the flow pattern of intake flow field. For large scale pumping station, there is enough space to arrange complex anti-vortex devices. Thus, a new type of combined diversion piers composed of double-I type pier, three-I type pier and cross anti-vortex baffle was proposed. In order to investigate the influences of combined division piers on flow pattern, four cases with different geometry and location parameters are designed. The results of numerical simulation and site tests show that the combined diversion piers could effectively improve the intake flow field of pumping station with headrace pipe. As for pumping station with headrace pipe, the distance between inlet section of fore-bay and leading edge of double-I type diversion pier should be 0.25L-0.53L (where L is the length of fore-bay). The distance between inlet section of fore-bay and trailing edge of double-I type diversion pier should be 0.5L-0.73L. The total length of double-I type pier should be 0.2L-0.25L.

  19. Particle Flows in Pumped DIII-D Discharges

    Energy Technology Data Exchange (ETDEWEB)

    Porter, G.D.; Rognlien, T.D.; Rensink, M.E.; Wolf, N.; West, W.P.

    2000-05-17

    The dynamics of particle flows in the DIII-D tokamak for two divertor configurations is considered. Fuel and intrinsic carbon impurity flows are analyzed using experimental data and 2D fluid plasma simulations. The flows in puff and pump experiments done in an open and a closed divertor geometry are described. It is shown that the flow of fuel particles is sensitive to divertor geometry. The pumping efficiency of the DIII-D cryopumps is a factor of 2 higher in a closed geometry than an open. The core refueling rate of an open divertor is a factor of 2 higher than that of a closed divertor. In contrast, the flow of impurity carbon particles is insensitive to divertor geometry. Both the core carbon content and the fraction of the carbon source which penetrates to the core is unchanged between an open and closed divertor. In addition, the core impurity content is found to be insensitive to the amplitude of gas puffing in the simulations.

  20. Quasi-steady state conditions in heterogeneous aquifers during pumping tests

    Science.gov (United States)

    Zha, Yuanyuan; Yeh, Tian-Chyi J.; Shi, Liangsheng; Huang, Shao-Yang; Wang, Wenke; Wen, Jet-Chau

    2017-08-01

    Classical Thiem's well hydraulic theory, other aquifer test analyses, and flow modeling efforts often assume the existence of ;quasi-steady; state conditions. That is, while drawdowns due to pumping continue to grow, the hydraulic gradient in the vicinity of the pumping well does not change significantly. These conditions have built upon two-dimensional and equivalent homogeneous conceptual models, but few field data have been available to affirm the existence of these conditions. Moreover, effects of heterogeneity and three-dimensional flow on this quasi-steady state concept have not been thoroughly investigated and discussed before. In this study, we first present a quantitative definition of quasi-steady state (or steady-shape conditions) and steady state conditions based on the analytical solution of two- or three-dimensional flow induced by pumping in unbounded, homogeneous aquifers. Afterward, we use a stochastic analysis to investigate the influence of heterogeneity on the quasi-steady state concept in heterogeneous aquifers. The results of the analysis indicate that the time to reach an approximate quasi-steady state in a heterogeneous aquifer could be quite different from that estimated based on a homogeneous model. We find that heterogeneity of aquifer properties, especially hydraulic conductivity, impedes the development of the quasi-steady state condition before the flow reaching steady state. Finally, 280 drawdown-time data from the hydraulic tomographic survey conducted at a field site corroborate our finding that the quasi-steady state condition likely would not take place in heterogeneous aquifers unless pumping tests last a long period. Research significance (1) Approximate quasi-steady and steady state conditions are defined for two- or three-dimensional flow induced by pumping in unbounded, equivalent homogeneous aquifers. (2) Analysis demonstrates effects of boundary condition, well screen interval, and heterogeneity of parameters on the

  1. Development of an implantable oxygenator with cross-flow pump.

    Science.gov (United States)

    Asakawa, Yuichi; Funakubo, Akio; Fukunaga, Kazuyoshi; Taga, Ichiro; Higami, Tetsuya; Kawamura, Tsuyoshi; Fukui, Yasuhiro

    2006-01-01

    Thrombogenicity, a problem with long-term artificial lungs, is caused by blood-biomaterial interactions and is made worse by nonuniform flow, which also causes decreased gas exchange. To overcome these obstacles, we changed the inlet and added a uniform flow pump to our previous oxygenator design. Conventional membrane oxygenators have a (1/2)-inch port for the inlet of blood. These port structures make it difficult for the blood to flow uniformly in the oxygenator. In addition, the complex blood flow patterns that occur in the oxygenator, including turbulence and stagnation, lead to thrombogenicity. A cross-flow pump (CFP) can result in uniform blood flow to the inlet side of an oxygenator. In this study, we evaluated the usefulness of an integrated oxygenator with a fiber bundle porosity of 0.6 and a membrane surface area of 1.3 m2. The inlet part of the oxygenator is improved and better fits the outlet of the CFP. Each of the three models of the improved oxygenator has a different inlet taper angle. The computational fluid dynamics analysis showed that, compared with the original design, uniform flow of the integrated oxygenator improved by 88.8% at the hollow fiber membrane. With the integrated oxygenator, O2 transfer increased by an average of 20.8%, and CO2 transfer increased by an average of 35.5%. The results of our experiments suggest that the CFP, which produces a wide, uniform flow to the oxygenator, is effective in attaining high gas exchange performance.

  2. Large-Eddy-Simulation-based analysis of complex flow structures within the volute of a vaneless centrifugal pump

    Indian Academy of Sciences (India)

    TAIMOOR ASIM; RAKESH MISHRA

    2017-04-01

    Centrifugal pumps are very common in many fluid handling industrial applications, such as petrochemicals, oil and gas, etc. Although the design practices for centrifugal pumps are well established, efforts are directed towards optimising such systems for better operational efficiencies. In order to optimally design centrifugal pumps, it is beneficial to first understand the complex flow phenomena within different sections of the pump for a variety of operating conditions. This is normally achieved through the use of modern techniques,such as Computational Fluid Dynamics (CFD), where the flow within centrifugal pumps can be numerically modelled and important flow features can be analysed for better understanding of interactions amongst different process variables. CFD offers different turbulence modelling techniques with an aim to predict realistic flow approximations. Large Eddy Simulation (LES) offers a more accurate solution to this, in which the larger eddies are resolved while smaller eddies are modelled; hence predictions using LES are more realistic. Further, in turbulence modelling within centrifugal pumps, it is also important to model the complete interaction amongst different variables rather than a simplistic single blade passage flow analysis. In the present work, the complex blade–tongue interactions and their consequent effects on the pressure fluctuations within the volute have been evaluated. It is seen that the secondary flow features in the near-tongue regions due to blade interactions with the tongue affect the flow characteristics within the volute considerably.

  3. Flow in a Low Specific Speed Centrifugal Pump Using PIV

    Directory of Open Access Journals (Sweden)

    Cui Dai

    2013-01-01

    Full Text Available The interflow plays important roles in centrifugal pump design. In order to study the effect of rotation and z-axis on internal flow, two-dimensional particle image velocimetry (PIV measurements have been performed to measure the steady velocity field on three planes in all impeller passages of a low specific-speed centrifugal pump. The results show that the relative velocity flows in blade passages are obviously different in terms of the positions of the blade relative to the tongue. The interaction between the impeller and tongue changes the occurrence and development of low velocity region with time. From shroud to hub, the relative velocity gradually increases, and the minimum value moves toward the suction surface. On the midplane, the magnitude increases with increased flow rate from pressure surface to suction surface, while at the shroud and hub, the measured velocity first increases with decreased flow rate from the blade pressure surface to nearly ζ = 0.5 to 0.6.

  4. Experimental investigation and numerical analysis of unsteady attached sheet-cavitating flows in a centrifugal pump

    Institute of Scientific and Technical Information of China (English)

    LIU Hou-lin; LIU Dong-xi; WANG Yong; WU Xian-fang; WANG Jian; DU Hui

    2013-01-01

    This paper studies the attached sheet cavitation in centrifugal pumps.A pump casted from Perspex is used as the test subject.The cavitation bubbles were observed in the entrance of the impeller and the drops of the head coefficients were measured under different operating conditions.A Filter-Based Model (FBM),derived from the RNG k-ε model,and a modified Zwart model are adopted in the numerical predictions of the unsteady cavitating flows in the pump.The simulations are carried out and the results are compared with experimental results for 3 different flow coefficients,from 0.077 to 0.114.Under four operating conditions,qualitative comparisons are made between experimental and numerical cavitation patterns,as visualized by a high-speed camera and described as isosurfaces of the vapour volume fraction αv =0.1.It is shown that the simulation can truly represent the development of the attached sheet cavitation in the impeller.At the same time,the curves for the drops of the head coefficients obtained from experiments and calculations are also quantitatively compared,which shows that the decline of the head coefficients at every flow coefficient is correctly captured,and the prediction accuracy is high.In addition,the detailed analysis is made on the vapour volume fraction contours on the plane of span is 0.5 and the loading distributions around the blade section at the midspan.It is shown that the FBM model and the modified Zwart model are effective for the numerical simulation of the cavitating flow in centrifugal pumps.The analysis results can also be used as the basis for the further research of the attached sheet cavitation and the improvement of centrifugal pumps.

  5. Development of a continuous-flow fluidic pump

    Energy Technology Data Exchange (ETDEWEB)

    Robinson, S.M.

    1985-08-01

    A study was made of a fluidic pump which utilizes gas pistons, a venturi-like reverse-flow-diverter, and a planar Y-type flow junction to produce a continuous flow of liquid from a system containing no moving parts. The study included an evaluation of the system performance and of methods for controlling the stability of the fluidic system. A mathematical model of the system was developed for steady-state operation using accepted theories of fluid mechanics. Although more elaborate models are needed for detailed design and optimization of specific systems, the model determined some of the main factors controlling the system performance and will be used in the development of more accurate models. 49 refs., 39 figs., 9 tabs.

  6. Low flow's fluctuation characteristics in pump-turbine's pump mode%水泵水轮机泵工况小流量波动特性

    Institute of Scientific and Technical Information of China (English)

    王乐勤; 刘锦涛; 张乐福; 覃大清; 焦磊

    2011-01-01

    为了研究水泵在水轮机泵工况小流量下的流场特性,对某电站水泵水轮机进行建模.采用SIMPLEC算法和剪切压力传输模型(SST k-w)模拟泵工况的流场特性,分析当泵工况活动导叶处于设计开度时在小流量下转轮、导叶的流场,结合实验对水泵水轮机的性能进行对比计算.结果显示,在导叶设计开度下当体积流量为设计流量的15%~53%时扬程曲线有小幅度波动;流量越小在导叶间的类似射流现象越明显,随着流量降低涡结构逐渐增多并且尺度逐渐变大,以至于充满整个活动导叶与固定导叶之间的流域;导叶的存在是小流量下扬程小幅度波动的主要原因.以上结论均可为水泵水轮机的优化设计提供依据.%One power plant's pump-turbine was modeled in order to analyze the field characteristic with low flow conditions in pump mode of pump-turbine. The flow characteristic in pump mode was simulated by SIMPLEC algorithm and shear stress transmission (SST) k-w mode. The flow of runner and vanes was analyzed when pump mode was at the condition of that guide vanes were in designed opening and low flow. The performance of pump-turbine was analyzed combined with experimental results. Results show that the head line is in the small amplitude fluctuations when the flow is 15% - 53% of designed flow and vanes are in designed opening. The phenomenon like a jet between vanes is more obvious when lower flow. The number of vortex is gradually increasing with lower flow , and its scale becomes larger so that the field between stay vanes and guide vanes are filled with vortex. It is the vanes that make the head of pump-turbine fluctuate in small amplitude when the flow is low. Those results can be used to guide the pump-turbine's optimal design.

  7. Performance Test and Flow Measurement of Contra-Rotating Axial Flow Pump

    Institute of Scientific and Technical Information of China (English)

    Akinori Furukawa; Toru Shigemitsu; Satoshi Watanabe

    2007-01-01

    An application of contra-rotating rotors has been proposed against a demand for developing higher specific speed axial flow pump. In the present paper, the advantage and disadvantage of using contra-rotating rotors are described in comparison with conventional type of rotor-stator, based on theoretical and experimental investigations. The advantages are as follows: (1) The pump is inherently designed as smaller sized and at lower rotational speed. (2) A stable head-characteristic curve for flow rate with negative slope appears. (3)As the rear rotor rotational speed is varied as independent control of front rotor, the wider range of high performance operation is obtained by rear rotor speed control in addition to front rotor speed control. The disadvantages are as follows: (1) The structure of double shaft system becomes complex. (2) The pump performance is inferior at over flow rate as the rear rotor loading is weakened. (3) The blade rows interaction from rear rotor to front rotor more strongly appears. Then the rear rotor design is a key to achieve higher pump performance. Some methods to overcome these disadvantages will be discussed in more details toward wider usage of contra-rotating axial flow pump in various industrial fields.

  8. Numerical Analysis of Flow Phenomena in a Residual Heat Removal Pump

    Directory of Open Access Journals (Sweden)

    Jianping Yuan

    2015-02-01

    Full Text Available The hydraulic performances as well as the cavitation phenomena in a scaled residual heat removal pump were investigated by experimental and numerical methods, respectively. In particular, a 3D numerical model of cavitation was adopted to simulate the internal cavitating flow through the model pump. The hydraulic performances of the model pump predicted by numerical simulations were in good agreement with the corresponding experimental data. The main generation and evolution of attached cavitation throughout the blade channels at different cavitating conditions have been investigated using the vapor fraction ISO surface and in-plane velocity vectors. Results show that the low static pressure at the impeller inlet is the main reason for leading edge cavitation by correlation analysis of static pressure on the midspan of impeller. Cavitation proved to occur over a wide range of flow rates, producing a characteristic creeping shape of the head-drop curve and developing in the form of nonaxisymmetric cavities at design flow rate. Moreover, the occurrence of these cavities, attached to the suction surface of blades, was found to depend on the NPSHA value. Numerical and experimental results in this paper can provide better understanding of the origin of leading edge cavitation in residual heat removal pumps.

  9. Large-Eddy Simulation of Unsteady Flow in a Mixed-Flow Pump

    Directory of Open Access Journals (Sweden)

    Chisachi Kato

    2003-01-01

    Full Text Available This article describes the large-eddy simulation (LES of the internal flows of a high–specific-speed, mixed-flow pump at low flow-rate ratios over which measured head-flow characteristics exhibit weak instability. In order to deal with a moving boundary interface in the flow field, a form of the finite-element method in which overset grids are applied from multiple dynamic frames of reference has been developed. The method is implemented as a parallel program by applying a domain-decomposition programming model.

  10. Research on the induction motor current signature for centrifugal pump at cavitation condition

    Directory of Open Access Journals (Sweden)

    Yin Luo

    2015-11-01

    Full Text Available Cavitation is a major undesirable phenomenon for centrifugal pump because it can cause hydraulic performance deterioration, pump damage by pitting and material erosion, and structural vibration and noise. Cavitation can appear within the entire range of the operating conditions; therefore, it must be prevented by all means. Sensorless monitoring technology based on motor current signature analysis is non-intrusive and economic for monitoring motor-driven equipment. Thus, this technology is suitable for centrifugal pump systems. The motor current signature for centrifugal pump load at the cavitation condition is the basis of this technology. However, systematic research is lacking on sensorless monitoring technology based on motor current signature. As a result, the tentative exploration for motor current signature at cavitation load was conducted in this study. The results show that the stator current is still a sinusoidal alternating current strictly to the law of sine. Moreover, the root mean square of the current fluctuates because of different flow regimes in the cavitation progress and decreases because vapor density is smaller than water density when cavitation is fully formed. For the stator current spectrum, the noise level, noise distribution, rotation speed, and vane pass frequency components show features in the cavitation process. These indicator indexes change according to the stage of cavitation development. Thus, the motor current signature analysis is found to be a feasible and cost-effective method for the stages of cavitation condition.

  11. Research on Three-Dimensional Unsteady Turbulent Flow in Multistage Centrifugal Pump and Performance Prediction Based on CFD

    Directory of Open Access Journals (Sweden)

    Zhi-jian Wang

    2013-01-01

    Full Text Available The three-dimensional flow physical model of any stage of the 20BZ4 multistage centrifugal pump is built which includes inlet region, impeller flow region, guide-vane flow region and exit region. The three-dimensional unsteady turbulent flow numerical model is created based on Navier-Stoke solver and standard k-ε turbulent equations. The method of multireference frame (MRF and SIMPLE algorithm are used to simulate the flow in multistage centrifugal pump based on FLUENT software. The distributions of relative velocity, absolute velocity, static pressure, and total pressure in guide vanes and impellers under design condition are analyzed. The simulation results show that the flow in impeller is mostly uniform, without eddy, backflow, and separation flow, and jet-wake phenomenon appears only along individual blades. There is secondary flow at blade end and exit of guide vane. Due to the different blade numbers of guide vane and impeller, the total pressure distribution is asymmetric. This paper also simulates the flow under different working conditions to predict the hydraulic performances of centrifugal pump and external characteristics including flow-lift, flow-shaft power, and flow-efficiency are attained. The simulation results are compared with the experimental results, and because of the mechanical losses and volume loss ignored, there is a little difference between them.

  12. Viscosity-adjusted estimation of pressure head and pump flow with quasi-pulsatile modulation of rotary blood pump for a total artificial heart.

    Science.gov (United States)

    Yurimoto, Terumi; Hara, Shintaro; Isoyama, Takashi; Saito, Itsuro; Ono, Toshiya; Abe, Yusuke

    2016-09-01

    Estimation of pressure and flow has been an important subject for developing implantable artificial hearts. To realize real-time viscosity-adjusted estimation of pressure head and pump flow for a total artificial heart, we propose the table estimation method with quasi-pulsatile modulation of rotary blood pump in which systolic high flow and diastolic low flow phased are generated. The table estimation method utilizes three kinds of tables: viscosity, pressure and flow tables. Viscosity is estimated from the characteristic that differential value in motor speed between systolic and diastolic phases varies depending on viscosity. Potential of this estimation method was investigated using mock circulation system. Glycerin solution diluted with salty water was used to adjust viscosity of fluid. In verification of this method using continuous flow data, fairly good estimation could be possible when differential pulse width modulation (PWM) value of the motor between systolic and diastolic phases was high. In estimation under quasi-pulsatile condition, inertia correction was provided and fairly good estimation was possible when the differential PWM value was high, which was not different from the verification results using continuous flow data. In the experiment of real-time estimation applying moving average method to the estimated viscosity, fair estimation could be possible when the differential PWM value was high, showing that real-time viscosity-adjusted estimation of pressure head and pump flow would be possible with this novel estimation method when the differential PWM value would be set high.

  13. Improvement of the Efficiency of the Axial-Flow Pump at Part Loads due to Installing Outlet Guide Vanes Mechanism

    OpenAIRE

    Fan Yang; Hao-ru Zhao; Chao Liu

    2016-01-01

    In order to investigate the influence of adjustable outlet guide vane on the hydraulic performance of axial-flow pump at part loads, the axial-flow pump with 7 different outlet guide vane adjustable angles was simulated based on the RNG k-ε turbulent model and Reynolds time-averaged equations. The Vector graphs of airfoil flow were analyzed in the different operating conditions for different adjustable angles of guide vane. BP-ANN prediction model was established about the effect of adjustabl...

  14. Water pumping and analysis of flow in burrowing zoobenthos - a short overview

    DEFF Research Database (Denmark)

    Riisgård, Hans Ulrik; Larsen, Poul Scheel

    2005-01-01

    Burrowing animals maintain contact with the water above the sediment by pumping water through a tube system and therefore measurements of water pumping rate of burrowing animals is of crucial importance for the study of many processes both within and above the sea floor. This review deals...... with the measuring of water pumping and the analysis of flow generated by burrowing deposit- and filter-feeding zoobenthos in order to determine the type of pump and mechanisms involved, flow rate, pump pressure, and pumping power. The practical use of fluid mechanical principles is examined, and it is stressed...... that not only the pump pressure that a burrowing animal can apply is of interest for assessing the energy cost of pumping, but also the distribution of excess pressure along its burrow is of importance for assessing the seepage flow of oxygen-rich water into the sediment surrounding the burrow because...

  15. THREE-DIMENSIONAL COUPLED IMPELLER-VOLUTE SIMULATION OF FLOW IN CENTRIFUGAL PUMP AND PERFORMANCE PREDICTION

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    A three-dimensional turbulent flow through an entire centrifugal pump is simulated using k-ε turbulence model modified by rotation and curvature, SIMPLEC method and body-fitted coordinate. The velocity and pressure fields are obtained for the pump under various working conditions, which is used to predict the head and hydraulic efficiency of the pump, and the results correspond well with the measured values. The calculation results indicate that the pressure is higher on the pressure side than that on the suction side of the blade; The relative velocity on the suction side gradually decreases from the impeller inlet to the outlet, while increases on the pressure side, it finally results in the lower relative velocity on the suction side and the higher one on the pressure side at the impeller outlet; The impeller flow field is asymmetric, i.e. the velocity and pressure fields are totally different among all channels in the impeller; In the volute, the static pressure gradually increases with the flow route, and a large pressure gratitude occurs in the tongue; Secondary flow exists in the rear part of the spiral.

  16. Three-Dimensional Viscous Numerical Simulation of Tip Clearance Flow in Axial-Flow Pump

    Institute of Scientific and Technical Information of China (English)

    Changming Yang; Cichang Chen; Jinnuo Wang; Quankai Ji

    2003-01-01

    The blade tip clearance flow in axial-flow pump is simulated based on three-dimensional N-S equations, RNG k-ε turbulence model, and SIMPLEC algorithm. It shows that numerical results agree well with experiment data measured by 5-hole probe through validation. Flow fields at the blade tip and velocity distribution at the exit of rotor are analyzed in detail. The numerical results show that the increase in tip clearance reduces hydro-head, especially at small flow rate. Experiment equipment is also introduced.

  17. Numerical Calculation of the Three-Dimensional Swirling Flow Inside the Centrifugal Pump Volutes

    Directory of Open Access Journals (Sweden)

    E. Cezmi Nursen

    2003-01-01

    Full Text Available The flow inside the volute of a centrifugal pump is threedimensional and, depending upon the position of the inlet relative to the cross-section center line, a single or double swirling flow occurs. The purpose of this study was the calculation of the three-dimensional swirling flow inside the centrifugal pump volute.

  18. THEORETICAL FLOW MODEL THROUGH A CENTRIFUGAL PUMP USED FOR WATER SUPPLY IN AGRICULTURE IRRIGATION

    Directory of Open Access Journals (Sweden)

    SCHEAUA Fanel Dorel

    2017-05-01

    motion of the rotor. A theoretical model for calculating the flow of the working fluid through the interior of a centrifugal pump model is presented in this paper as well as the numerical analysis on the virtual model performed with the ANSYS CFX software in order to highlight the flow parameters and flow path-lines that are formed during centrifugal pump operation.

  19. Quality evaluation of energy consumed in flow regulation method by speed variation in centrifugal pumps

    Science.gov (United States)

    Morales, S.; Culman, M.; Acevedo, C.; Rey, C.

    2014-06-01

    Nowadays, energy efficiency and the Electric Power Quality are two inseparable issues in the evaluation of three-phase induction motors, framed within the program of Rational and Efficient Use of Energy (RUE).The use of efficient energy saving devices has been increasing significantly in RUE programs, for example the use of variable frequency drives (VFD) in pumping systems.The overall objective of the project was to evaluate the impact on power quality and energy efficiency in a centrifugal pump driven by an induction three-phase motor, using the flow control method of speed variation by VFD. The fundamental purpose was to test the opinions continuously heard about the use of flow control methods in centrifugal pumps, analyzing the advantages and disadvantages that have been formulated deliberately in order to offer support to the industry in taking correct decisions. The VFD changes the speed of the motor-pump system increasing efficiency compared to the classical methods of regulation. However, the VFD originates conditions that degrade the quality of the electric power supplied to the system and therefore its efficiency, due to the nonlinearity and presence of harmonic currents. It was possible to analyze the power quality, ensuring that the information that comes to the industry is generally biased.

  20. An investigational study of minimum rotational pump speed to avoid retrograde flow in three centrifugal blood pumps in a pediatric extracorporeal life support model.

    Science.gov (United States)

    Clark, Joseph B; Guan, Yulong; McCoach, Robert; Kunselman, Allen R; Myers, John L; Undar, Akif

    2011-05-01

    During extracorporeal life support with centrifugal blood pumps, retrograde pump flow may occur when the pump revolutions decrease below a critical value determined by the circuit resistance and the characteristics of the pump. We created a laboratory model to evaluate the occurrence of retrograde flow in each of three centrifugal blood pumps: the Rotaflow, the CentriMag, and the Bio-Medicus BP-50. At simulated patient pressures of 60, 80, and 100 mmHg, each pump was evaluated at speeds from 1000 to 2200 rpm and flow rates were measured. Retrograde flow occurred at low revolution speeds in all three centrifugal pumps. The Bio-Medicus pump was the least likely to demonstrate retrograde flow at low speeds, followed by the Rotaflow pump. The CentriMag pump showed the earliest transition to retrograde flow, as well as the highest degree of retrograde flow. At every pump speed evaluated, the Bio-Medicus pump delivered the highest antegrade flow and the CentriMag pump delivered the least.

  1. Investigation of Flow Inside an Axial-Flow Pump of GV - IMP Type

    CERN Document Server

    Yevtushenko, A A; Fedotova, N A; Schelyaev, A Y; Konshin, V N; Yevtushenko, Anatoliy A.; Kochevsky, Alexey N.; Fedotova, Natalya A.; Schelyaev, Alexander Y.; Konshin, Vladimir N.

    2004-01-01

    The article describes research of fluid flow inside an axial-flow pump that includes guide vanes, impeller and discharge diffuser. Three impellers with different hub ratio were researched. The article presents the performance curves and velocity distributions behind each of the impeller obtained by computational and experimental ways at six different capacities. The velocity distributions behind the detached guide vanes of different hub ratio are also presented. The computational results were obtained using the software tools CFX-BladeGenPlus and CFX-TASCflow. The experimental performance curves were obtained using the standard procedure. The experimental velocity distributions were obtained by probing of the flow. Good correspondence of results, both for performance curves and velocity distributions, was obtained for most of the considered cases. As it was demonstrated, the performance curves of the pump depend essentially on the impeller hub ratio. Velocity distributions behind the impeller depend strongly ...

  2. Investigation on transient flow of a centrifugal charging pump in the process of high pressure safety injection

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Fan, E-mail: zhangfan4060@gmail.com; Yuan, Shouqi; Fu, Qiang; Tao, Yi

    2015-11-15

    Highlights: • The transient flow characteristics of the charging pump with the first stage impeller in the HPSI process have been investigated numerically by CFD. • The hydraulic performance of the charging pump during the HPSI are discussed, andthe absolute errors between the simulated and measured results are analyzed in the paper. • Pressure fluctuation in the impeller and flow pattern in the impeller were studied in the HPSI process. It is influenced little at the beginning of the HPSI process while fluctuates strongly in the end of the HPSI process. - Abstract: In order to investigate the transient flow characteristics of the centrifugal charging pump during the transient transition process of high pressure safety injection (HPSI) from Q = 148 m{sup 3}/h to Q = 160 m{sup 3}/h, numerical simulation and experiment are implemented in this study. The transient flow rate, which is the most important factor, is obtained from the experiment and works as the boundary condition to accurately accomplish the numerical simulation in the transient process. Internal characteristics under the variable operating conditions are analyzed through the transient simulation. The results shows that the absolute error between the simulated and measured heads is less than 2.26% and the absolute error between the simulated and measured efficiency is less than 2.04%. Pressure fluctuation in the impeller is less influenced by variable flow rate in the HPSI process, while flow pattern in the impeller is getting better and better with the flow rate increasing. As flow rate increases, fluid blocks on the tongue of the volute and it strikes in this area at large flow rate. Correspondingly, the pressure fluctuation is intense and vortex occurs gradually during this period, which obviously lowers the efficiency of the pump. The contents of the current work can provide references for the design optimization and fluid control of the pump used in the transient process of variable operating

  3. Improvement of the Efficiency of the Axial-Flow Pump at Part Loads due to Installing Outlet Guide Vanes Mechanism

    Directory of Open Access Journals (Sweden)

    Fan Yang

    2016-01-01

    Full Text Available In order to investigate the influence of adjustable outlet guide vane on the hydraulic performance of axial-flow pump at part loads, the axial-flow pump with 7 different outlet guide vane adjustable angles was simulated based on the RNG k-ε turbulent model and Reynolds time-averaged equations. The Vector graphs of airfoil flow were analyzed in the different operating conditions for different adjustable angles of guide vane. BP-ANN prediction model was established about the effect of adjustable outlet guide vane on the hydraulic performance of axial-flow pump based on the numerical results. The effectiveness of prediction model was verified by theoretical analysis and numerical simulation. The results show that, with the adjustable angle of guide vane increasing along clockwise, the high efficiency area moves to the large flow rate direction; otherwise, that moves to the small flow rate direction. The internal flow field of guide vane is improved by adjusting angle, and the flow separation of tail and guide vane inlet ledge are decreased or eliminated, so that the hydraulic efficiency of pumping system will be improved. The prediction accuracy of BP-ANN model is 1%, which can meet the requirement of practical engineering.

  4. Megacity pumping and preferential flow threaten groundwater quality

    Science.gov (United States)

    Khan, Mahfuzur R.; Koneshloo, Mohammad; Knappett, Peter S. K.; Ahmed, Kazi M.; Bostick, Benjamin C.; Mailloux, Brian J.; Mozumder, Rajib H.; Zahid, Anwar; Harvey, Charles F.; van Geen, Alexander; Michael, Holly A.

    2016-09-01

    Many of the world's megacities depend on groundwater from geologically complex aquifers that are over-exploited and threatened by contamination. Here, using the example of Dhaka, Bangladesh, we illustrate how interactions between aquifer heterogeneity and groundwater exploitation jeopardize groundwater resources regionally. Groundwater pumping in Dhaka has caused large-scale drawdown that extends into outlying areas where arsenic-contaminated shallow groundwater is pervasive and has potential to migrate downward. We evaluate the vulnerability of deep, low-arsenic groundwater with groundwater models that incorporate geostatistical simulations of aquifer heterogeneity. Simulations show that preferential flow through stratigraphy typical of fluvio-deltaic aquifers could contaminate deep (>150 m) groundwater within a decade, nearly a century faster than predicted through homogeneous models calibrated to the same data. The most critical fast flowpaths cannot be predicted by simplified models or identified by standard measurements. Such complex vulnerability beyond city limits could become a limiting factor for megacity groundwater supplies in aquifers worldwide.

  5. Parameter estimation and actuator characteristics of hybrid magnetic bearings for axial flow blood pump applications.

    Science.gov (United States)

    Lim, Tau Meng; Cheng, Shanbao; Chua, Leok Poh

    2009-07-01

    Axial flow blood pumps are generally smaller as compared to centrifugal pumps. This is very beneficial because they can provide better anatomical fit in the chest cavity, as well as lower the risk of infection. This article discusses the design, levitated responses, and parameter estimation of the dynamic characteristics of a compact hybrid magnetic bearing (HMB) system for axial flow blood pump applications. The rotor/impeller of the pump is driven by a three-phase permanent magnet brushless and sensorless motor. It is levitated by two HMBs at both ends in five degree of freedom with proportional-integral-derivative controllers, among which four radial directions are actively controlled and one axial direction is passively controlled. The frequency domain parameter estimation technique with statistical analysis is adopted to validate the stiffness and damping coefficients of the HMB system. A specially designed test rig facilitated the estimation of the bearing's coefficients in air-in both the radial and axial directions. Experimental estimation showed that the dynamic characteristics of the HMB system are dominated by the frequency-dependent stiffness coefficients. By injecting a multifrequency excitation force signal onto the rotor through the HMBs, it is noticed in the experimental results the maximum displacement linear operating range is 20% of the static eccentricity with respect to the rotor and stator gap clearance. The actuator gain was also successfully calibrated and may potentially extend the parameter estimation technique developed in the study of identification and monitoring of the pump's dynamic properties under normal operating conditions with fluid.

  6. Production of Hyperpolarized 129Xe Gas Without Nitrogen by Optical Pumping at 133Cs D2 line in Flow System

    Institute of Scientific and Technical Information of China (English)

    ZHOU Xin; SUN Xian-Ping; LUO Jun; ZENG Xi-Zhi; LIU Mai-Li; ZHAN Ming-Sheng

    2004-01-01

    @@ We report production of hyperpolarized 129Xe gas via spin-exchange with optically pumped Cs atoms at the D2 line, achieved at low magnetic field in a flow system and in the absence of nitrogen gas. The nuclear spin polarization of hyperpolarized 129Xe gas is enhanced by a factor of 10000 compared to that without optical pumping under the same condition, which corresponds to polarization of about 2.66%. Due to the high spin polarization, the radiation damping of hyperpolarized 129Xe gas has also been observed in the flow system.

  7. Operation control of fluids pumping in curved pipes during annular flow: a numerical evaluation

    Directory of Open Access Journals (Sweden)

    T Andrade

    2016-10-01

    Full Text Available To generate projects which provide significant volume recovery from heavy oils reservoirs and improve existing projects, is important to develop new production and transport technologies, especially in the scenario of offshore fields. The core-flow technique is one of new technologies used in heavy oil transportation. This core-flow pattern is characterized by a water pellicle that is formed close or adjacent to the inner wall of the pipe, functioning as a lubricant. The oil flows in the center of the pipe causing a reduction in longitudinal pressure drop. In this sense, this work presents a numerical study of heavy oil annular flow (core-flow assisted by computational tool ANSYS CFX® Release 12.0. It was used a three-dimensional, transient and isothermal mathematical model considered by the mixture and turbulence - models to address the water-heavy oil two-phase flow, assuming laminar flow for oil phase and turbulent flow for water phase. Results of the pressure, velocity and volume fraction distributions of the phases and the pressure drop for different operation conditions are presented and evaluated. It was observed that the oil core flowing eccentrically in the pipe and stops of the water flux considerably increases the pressure drop in the pipe after the restart of the pump.

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

    CERN Document Server

    Kochevsky, A N

    2005-01-01

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

  9. Investigations of hydraulic operating conditions of air lift pump with three types of air-water mixers

    Directory of Open Access Journals (Sweden)

    Kalenik Marek

    2015-03-01

    Full Text Available Investigations of hydraulic operating conditions of air lift pump with three types of air-water mixers. The paper presents the analysis of results of the investigations concerning the influence of various constructive solutions of the air-water mixers on hydraulic operating conditions of the air lift pump. The scope of the investigations encompassed the determination of characteristics of delivery head and delivery rate for three types of air-water mixers applied in the constructed air lift pump. Using the obtained results, the efficiency of the three types of air-water mixers applied in this air lift pump was determined. The analysis was carried out and there was checked whether the improved analytical Stenning-Martin model can be used to design air lift pumps with the air-water mixers of these types. The highest capacity in the water transport was reached by the air lift pump with the 1st type air-water mixer, the lowest one – with the 3rd type air-water mixer. The water flow in the air lift pump increases along with the rise in the air flow. The lower are the hydraulic losses generated during flow of the air flux by the air-water mixer, the higher is the air lift pump capacity. Along with the rise in the water delivery head, the capacity of the air lift pump decreases. The highest efficiency is reached by the air lift pump with the 1st type air-water mixer, the lowest – with the 3st type air-water mixer. The efficiency of the air lift pump for the three investigated types of air-water mixers decreases along with the rise in air flow rate and water delivery head. The values of submergence ratio (h/L of the delivery pipe, calculated with the use of the improved analytical Stenning-Martin model, coincide quite well with the values of h/L determined from the measurements.

  10. PIV Investigations of the Flow Field in the Volute of a Rotary Blood Pump

    Science.gov (United States)

    Sankovic, John M.; Kadambi, Jaikrishnan R.; Smith, William A.; Wernet, Mark P.

    2004-01-01

    A full-size acrylic model of a rotary blood pump was developed in order to utilize Particle Image Velocimetry (PIV) to make measurements of the fluid velocities and turbulent stresses throughout the device. The development of an understanding of the hemodynamics within the blood pump is critical to the development and validation of computational models. A blood analog solution, consisting of sodium iodide solution and glycerin, was developed to match physiological kinematic viscosity. The refractive indices of the fluid, the pump casing, and the impeller were matched to facilitate the use of PIV to make velocity measurements. Velocity measurements made in the volute exit/diffuser region are presented for pumps speeds of 3000-3850 rpm. At each speed data were obtained at a physiological pressure of 12 kPa and at a maximum flow condition. Four hundred data pairs were used for each resultant mean velocity vector value, representing greater than an order of magnitude more data pairs than reported previously in the literature on similar devices and resulting in velocity uncertainty levels of approximately 22.9%.

  11. An evaluation of a hubless inducer and a full flow hydraulic turbine driven inducer boost pump

    Science.gov (United States)

    Lindley, B. K.; Martinson, A. R.

    1971-01-01

    The purpose of the study was to compare the performance of several configurations of hubless inducers with a hydrodynamically similar conventional inducer and to demonstrate the performance of a full flow hydraulic turbine driven inducer boost pump using these inducers. A boost pump of this type consists of an inducer connected to a hydraulic turbine with a high speed rotor located in between. All the flow passes through the inducer, rotor, and hydraulic turbine, then into the main pump. The rotor, which is attached to the main pump shaft, provides the input power to drive the hydraulic turbine which, in turn, drives the inducer. The inducer, rotating at a lower speed, develops the necessary head to prevent rotor cavitation. The rotor speed is consistent with present main engine liquid hydrogen pump designs and the overall boost pump head rise is sufficient to provide adequate main pump suction head. This system would have the potential for operating at lower liquid hydrogen tank pressures.

  12. Mixing Under Transcritical Flow Conditions

    Science.gov (United States)

    2011-03-01

    Raynal et al. [3] studied variable-density jets using hot - wire anemometry . They used their power spectral results to find that flow stability was not...affected by the presence of the hot - wire one jet diameter downstream the exit of the flow at several density ratios. They did find that as the probe...of the spectral level, which reflects the spatial amplification of the perturbations as the hot - wire was moved downstream. The power spectra also

  13. Flow dynamical behavior and performance of a micro viscous pump with unequal inlet and outlet areas

    Directory of Open Access Journals (Sweden)

    Chenhui Hu

    2016-01-01

    Full Text Available The micro viscous pump is an important type of fluidic device. Optimizing the working performance of the pump is crucial for its wider application. A micro viscous pump design with unequal inlet and outlet areas is proposed in this paper. The flow field of the viscous pump is investigated using 2D laminar simulations. The mass flow rate and driving power are studied with different opening angles. The effects of the Reynolds number and the pressure load on the working performance are discussed in detail. Flow structures and vortex evolution are analyzed. With larger inlet and outlet areas, a higher mass flow rate is obtained and less driving power is achieved. A high pressure load results in a reduction in mass flow rate and an increase in driving power. Pumps with large opening angles are more susceptive to the Reynolds number and the pressure load. The adverse impact of the pressure load can be reduced by increasing the rotor speed. The vortex structure is affected by the geometric and operating parameters in the flow field. The flow dynamical behavior of the viscous pump exerts significant influence on its pumping ability. The present work gives rise to performance improvements for the micro viscous pump.

  14. Numerical simulation and analysis of solid-liquid two-phase three-dimensional unsteady flow in centrifugal slurry pump

    Institute of Scientific and Technical Information of China (English)

    吴波; 汪西力; 徐海良

    2015-01-01

    Based on RNGk-ε turbulence model and sliding grid technique, solid−liquid two-phase three-dimensional (3-D) unsteady turbulence of full passage in slurry pump was simulated by means of Fluent software. The effects of unsteady flow characteristics on solid−liquid two-phase flow and pump performance were researched under design condition. The results show that clocking effect has a significant influence on the flow in pump, and the fluctuation of flow velocity and pressure is obvious, particularly near the volute tongue, at the position of small sections of volute and within diffuser. Clocking effect has a more influence on liquid-phase than on solid-phase, and the wake-jet structure of relative velocity of solid-phase is less obvious than liquid-phase near the volute tongue and the impeller passage outlet. The fluctuation of relative velocity of solid-phase flow is 7.6% smaller than liquid-phase flow at the impeller outlet on circular path. Head and radial forces of the impeller are 8.1% and 85.7% of fluctuation, respectively. The results provide a theoretical basis for further research for turbulence, improving efficient, reducing the hydraulic losses and wear. Finally, field tests were carried out to verify the operation and wear of slurry pump.

  15. Noninvasive average flow estimation for an implantable rotary blood pump: a new algorithm incorporating the role of blood viscosity.

    Science.gov (United States)

    Malagutti, Nicolò; Karantonis, Dean M; Cloherty, Shaun L; Ayre, Peter J; Mason, David G; Salamonsen, Robert F; Lovell, Nigel H

    2007-01-01

    The effect of blood hematocrit (HCT) on a noninvasive flow estimation algorithm was examined in a centrifugal implantable rotary blood pump (iRBP) used for ventricular assistance. An average flow estimator, based on three parameters, input electrical power, pump speed, and HCT, was developed. Data were collected in a mock loop under steady flow conditions for a variety of pump operating points and for various HCT levels. Analysis was performed using three-dimensional polynomial surfaces to fit the collected data for each different HCT level. The polynomial coefficients of the surfaces were then analyzed as a function of HCT. Linear correlations between estimated and measured pump flow over a flow range from 1.0 to 7.5 L/min resulted in a slope of 1.024 L/min (R2=0.9805). Early patient data tested against the estimator have shown promising consistency, suggesting that consideration of HCT can improve the accuracy of existing flow estimation algorithms.

  16. Magnetohydrodynamic pump with a system for promoting flow of fluid in one direction

    Science.gov (United States)

    Lemoff, Asuncion V.; Lee, Abraham P.

    2010-07-13

    A magnetohydrodynamic pump for pumping a fluid. The pump includes a microfluidic channel for channeling the fluid, a MHD electrode/magnet system operatively connected to the microfluidic channel, and a system for promoting flow of the fluid in one direction in the microfluidic channel. The pump has uses in the medical and biotechnology industries for blood-cell-separation equipment, biochemical assays, chemical synthesis, genetic analysis, drug screening, an array of antigen-antibody reactions, combinatorial chemistry, drug testing, medical and biological diagnostics, and combinatorial chemistry. The pump also has uses in electrochromatography, surface micromachining, laser ablation, inkjet printers, and mechanical micromilling.

  17. Desarrollo de un prototipo de bomba de flujo pulsátil para caracterizar las condiciones hidrodinámicas en un ambiente de circulación extracorpórea Development of a prototype of pulsatile flow pump for characterizing the hydrodinamic conditions in an extracorporeal circulation setting

    Directory of Open Access Journals (Sweden)

    John Bustamante O

    2007-02-01

    Full Text Available Es difícil generar con bombas convencionales las condiciones de flujo del sistema cardiovascular, con las cuales se emulen condiciones hemodinámicas para evaluar diferentes dispositivos interpuestos a la corriente sanguínea. Para resolver este inconveniente, se desarrolló un sistema automatizado de bombeo de flujo pulsátil, conformado por un controlador difuso que captura datos de los instrumentos de monitoreo de variables hidrodinámicas a través de una interfaz de adquisición, y aplica señales de control a una bomba de flujo pulsátil. Este sistema permite hacer pruebas hidromecánicas que brindan elementos para interpretar la influencia de las variables que intervienen en el flujo pulsante y simular condiciones hemodinámicas en un ambiente de circulación extracorpórea. Mediante técnicas de diseño asistido por computador, se construyó una bomba de diafragma accionada neumáticamente. El controlador se desarrolló mediante la técnica de Fuzzi Control®, el cual regula el pulso y el flujo de acuerdo con parámetros y datos capturados con la interfaz de adquisición. Las pruebas del prototipo se realizaron en un laboratorio de fluidos variando frecuencia, resistencia hidráulica, viscosidad y presión de pulso, imitando las condiciones hemodinámicas de un adulto y usando como fluido de trabajo una solución acuosa con 5 cPo a 370C, para simular la viscosidad sanguínea a temperatura corporal. La reproducción de una bomba que sirve para analizar el efecto de las variables en el flujo pulsante, puede usarse en el estudio de diferentes dispositivos intravasculares y ayudar a refinar aspectos técnicos y funcionales en el estudio preliminar de máquinas de circulación extracorpórea.With conventional pumps, it is difficult to generate the cardiovascular system conditions that may emulate hemodynamic conditions for evaluating different devices interposed to the blood flow. In order to resolve this inconvenient, an automated pulsatile

  18. A miniature intraventricular axial flow blood pump that is introduced through the left ventricular apex.

    Science.gov (United States)

    Yamazaki, K; Umezu, M; Koyanagi, H; Kitamura, M; Eishi, K; Kawai, A; Tagusari, O; Niinami, H; Akimoto, T; Nojiri, C

    1992-01-01

    A new intraventricular axial flow blood pump has been designed and developed as an implantable left ventricular assist device (LVAD). The pump consists of a tube housing (10 cm in length and 14 mm in diameter), a three-vane impeller combined with a guide vane, and a DC motor. This pump is introduced into the LV cavity through the LV apex, and the outlet cannula is passed antegrade across the aortic valve. Blood is withdrawn from the LV through the inlet ports at the pump base, and discharged into the ascending aorta. A pump flow of > 8 L/min was obtained against 90 mmHg differential pressure in the mock circulatory system. In an acute dog model, this pump could produce a sufficient output of 200 ml/kg/min. In addition, the pump flow profile demonstrated a pulsatile pattern, although the rotation speed was fixed. This is mainly due to the changes in flow rate during a cardiac cycle--that is, during systole, the flow rate increases to the maximum, while the differential pressure between the LV and the aorta decreases to the minimum. Thus, this simple and compact axial flow blood pump can be a potential LVAD, with prompt accessibility and need for less invasive surgical procedures.

  19. Flow Pattern Analysis and Performance Improvement of Regenerative Flow Pump Using Blade Geometry Modification

    Directory of Open Access Journals (Sweden)

    J. Nejadrajabali

    2016-01-01

    Full Text Available Regenerative pump is a low specific speed and rotor-dynamic turbomachine capable of developing high heads at low flow rates. In this paper, a numerical study has been carried out in order to investigate the effect of blade angle on the performance of a regenerative pump. Two groups of impellers were employed. The first type has symmetric angle blades with identical inlet/outlet angles of ±10°, ±30°, and ±50° and the second group has nonsymmetric angle blades in which the inlet angle was set to 0° and six different angles of ±10°, ±30°, and ±50° were designed for the outlet of the blades. A total of 12 impellers, as well as primary radial blades impeller, were investigated in this study. The results showed that all forward blades have higher head coefficients than radial blades impeller at design flow coefficient. It was found that regenerative pumps with symmetric angle forward blades have better performance than other types. Also, it is worth mentioning that the highest head coefficient and efficiency occur at angle +10<β<+30 of symmetric angle blades. It was found that the maximum efficiency occurs at angle of +15.5° by curve fitting to the data obtained from numerical simulations for symmetric angle forward blades.

  20. FEATURES OF LONG-TERM MECHANICAL CIRCULATORY SUPPORT WITH CONTINUOUS-FLOW PUMP

    Directory of Open Access Journals (Sweden)

    G. P. Itkin

    2012-01-01

    Full Text Available In a review of the comparative analysis of methods and tools for long-term mechanical circulatory support with continuous flow and pulsatile flow implantable pumps. Particular attention is paid to the choice of the optimal modes of the operation of pumps based on the physical principles of the interaction between a the steady flow of blood to the pulsatile mechanics of the heart chambers. 

  1. A Variable Refrigerant Flow Heat Pump Computer Model in EnergyPlus

    Energy Technology Data Exchange (ETDEWEB)

    Raustad, Richard A. [Florida Solar Energy Center

    2013-01-01

    This paper provides an overview of the variable refrigerant flow heat pump computer model included with the Department of Energy's EnergyPlusTM whole-building energy simulation software. The mathematical model for a variable refrigerant flow heat pump operating in cooling or heating mode, and a detailed model for the variable refrigerant flow direct-expansion (DX) cooling coil are described in detail.

  2. The Combination of Micro Diaphragm Pumps and Flow Sensors for Single Stroke Based Liquid Flow Control.

    Science.gov (United States)

    Jenke, Christoph; Pallejà Rubio, Jaume; Kibler, Sebastian; Häfner, Johannes; Richter, Martin; Kutter, Christoph

    2017-04-03

    With the combination of micropumps and flow sensors, highly accurate and secure closed-loop controlled micro dosing systems for liquids are possible. Implementing a single stroke based control mode with piezoelectrically driven micro diaphragm pumps can provide a solution for dosing of volumes down to nanoliters or variable average flow rates in the range of nL/min to μL/min. However, sensor technologies feature a yet undetermined accuracy for measuring highly pulsatile micropump flow. Two miniaturizable in-line sensor types providing electrical readout-differential pressure based flow sensors and thermal calorimetric flow sensors-are evaluated for their suitability of combining them with mircopumps. Single stroke based calibration of the sensors was carried out with a new method, comparing displacement volumes and sensor flow volumes. Limitations of accuracy and performance for single stroke based flow control are described. Results showed that besides particle robustness of sensors, controlling resistive and capacitive damping are key aspects for setting up reproducible and reliable liquid dosing systems. Depending on the required average flow or defined volume, dosing systems with an accuracy of better than 5% for the differential pressure based sensor and better than 6.5% for the thermal calorimeter were achieved.

  3. Review of Operational Challenges and Changing Conditions associated with Offshore Submerged Vertical Pumping Station

    Science.gov (United States)

    Samsudin, M. L.; Munisamy, K. M.; Thangaraju, S. K.

    2015-09-01

    Cooling water system is one of the essential auxiliary systems for a power generating plant. The decision to have an offshore pumping station, instead of onshore station, may have been driven by the scarcity in land area or for direct water supply access. However, the design has several disadvantages such as tendency for sediment intakes, limited condition monitoring activities and inaccessible sump for maintenance and modification. The paper reviews and lists several potential operational challenges and difficulties experienced with the offshore station. The influences of changing conditions such as varying seawater tide level, clogged intake screen, intake sedimentation issues and marine fouling on the sump walls and structures, are discussed and mitigating solutions are identified. While it is impractical to conduct physical model test for studying flow pattern, the CFD method can be an attractive assessment tools. In addition to this, a review of plant operating parameters can assist in identifying flow anomalies to anticipate potential deterioration. Finally the difficulty in incorporating the solutions to vortex and sediment problems within the sump is highlighted with preference for those which can be managed by limited access or those which are moveable with the vertical pump.

  4. Multi-Phase Flow and Heat Transfer of a Micro-Pump Thermally Driven by a Multi-Output Pulse Laser

    Institute of Scientific and Technical Information of China (English)

    HUAI Xiu-Lan; TANG Zhi-Wei; WANG Guo-Xiang; WANG Wei-Wei

    2005-01-01

    @@ We present an experimental study of multi-phase flow and heat transfer in a micro-tube induced by a multi-output pulse laser. Extensive flow and heat transfer measurements and visualization experiments have been carried out to characterize the micro-pump behaviour under various conditions. The experiments reveal extremely unsteady and complex flow patterns in the micro tube with the flow closely related with generation and collapse of bubbles.It is found that the flow rates are controlled by the heating and condensation conditions within the tube. The laser pulse duration, pulse interval and output-power as well as the tube diameter all show a strong influence on the flow rate of the micro-pump. This study provides a basis for the design of thermally-driven micro-pump induced by a pulsed laser beam.

  5. Numerical simulation on internal flow characteristics in the discharge chamber of an afterburning fuel pump under off-design conditions%加力燃油泵压出室非设计工况内流特征数值模拟

    Institute of Scientific and Technical Information of China (English)

    薛梅新; 吴迪; 朴英

    2012-01-01

    The unsteady flow in an afterburning oil pump on a certain type of aero-engine was simulated for the uneommon cavitation damage problem near its casing tongue, with arbitrary sliding mesh technology. The discharge chamber internal flow characteristics at off-design conditions were investigated to find out possible conditions causing the casing tongue cavitation. The results showed that. under large flow-rate condition, there are two separated vortices of different sizes located in the cone-shaped tube passage, while the fuel flowed past the casing wall without obvious separation in the annular chamber, which hardly trigger cavitation under small flow-rate condition, the two separated vortices extend to take up most part of the cone-shaped passage, incoming flow of the diffuser is choke up with a part of the fuel blocked at right side flowing back to the annular chamber around the tongue. As a result, serious flow separation is raised with a high pressure decrease, which is expected to generate cavitation and following damage on the casing tongue.%针对某型航空发动机加力燃油泵隔舌空蚀破坏,采用滑移网格技术模拟泵内非定常流场,揭示了压出室在典型非设计工况下的内流特征,研究了隔舌处的空化机理.计算结果表明:大流量工况,扩散管锥形段存在大小两个分离涡,而环形腔室隔舌段燃油以相切方式流经隔舌壁面,无明显流动分离,不会发生空化;而小流量工况,扩散管锥形段内两分离涡扩展到大部分区域,右半侧部分阻滞燃油在反向流向涡作用下,绕流隔舌上部,在隔舌下游形成了明显分离涡,导致隔舌壁面静压急剧降低,进而引发空化,产生空蚀破坏.

  6. NUMERICAL SIMULATION FOR INCOMPRESSIBLE TURBULENT FLOW IN THE IMPELLER OF SEWAGE PUMP

    Institute of Scientific and Technical Information of China (English)

    Yang Minguan; Guo Xiaomei; Wang Chunlin; Jia Weidong; Yuan Chunyuan

    2004-01-01

    The 3-D turbulent flow in the impeller of sewage pump is simulated.The time-averaged N-S equations and the k-ε turbulent model is modified.The calculation is carried out in body-fitted coordinated grid by applying SIMPLE-C algorithm.The calculated velocity, pressure distributions of the turbulent flow in the sewage pump are obtained for the first time, which will be helpful for the optimal design and performance prediction of sewage pumps on the basis of flow field simulation.

  7. Influence of tip clearance on pressure fluctuations in an axial flow pump

    Energy Technology Data Exchange (ETDEWEB)

    Feng, Jianjun; Luo, Xingqi; Guo, Pengcheng; Wu, Guangkuan [Xi' an University, Xi' an (China)

    2016-04-15

    Rotor-stator interaction in axial pumps can produce pressure fluctuations and further vibrations even damage to the pump system in some extreme case. In this paper, the influence of tip clearance on pressure fluctuations in an axial flow water pump has been investigated by numerical method. Three-dimensional unsteady flow in the axial flow water pump has been simulated with different tip clearances between the impeller blade tip and the casing wall. In addition to monitoring pressure fluctuations at some typical points, a new method based on pressure statistics was proposed to determine pressure fluctuations at all grid nodes inside the whole pump. The comparison shows that the existence of impeller tip clearance magnifies the pressure fluctuations in the impeller region, from the hub to shroud. However, the effect on pressure fluctuation in the diffuser region is not evident. Furthermore, the tip clearance vortex has also been examined under different tip clearances.

  8. [Research on flow characteristics in a non-blade centrifugal blood pump based on CFD technology].

    Science.gov (United States)

    Cheng, Yunzhang; Luo, Binhai; Wu, Wenquan; Jiang, Lei

    2010-10-01

    The problem of thrombus and hemolysis in blood pump has always been an important topic to study in the development of the blood pump. Numbers of research results show that it is the complicated flow and the high shear stress of the mechanical movement that result in the thrombus and hemolysis. In this study, with the cooperation of Shanghai Children's Medical Center, we have used computational fluid dynamics (CFD) commercial software FLUENT to compute and analyze the flow characteristics in a non-blade centrifugal blood pump. The results figure out that this pump has a reasonable flow distribution and the shear stress distribution is under the critical broken state of red blood cell; meanwhile, there is less thrombus and hemolysis in this pump. So it is in the foreground for clinical use.

  9. Assessment of turbulence models for pulsatile flow inside a heart pump.

    Science.gov (United States)

    Al-Azawy, Mohammed G; Turan, A; Revell, A

    2016-02-01

    Computational fluid dynamics (CFD) is applied to study the unsteady flow inside a pulsatile pump left ventricular assist device, in order to assess the sensitivity to a range of commonly used turbulence models. Levels of strain and wall shear stress are directly relevant to the evaluation of risk from haemolysis and thrombosis, and thus understanding the sensitivity to these turbulence models is important in the assessment of uncertainty in CFD predictions. The study focuses on a positive displacement or pulsatile pump, and the CFD model includes valves and moving pusher plate. An unstructured dynamic layering method was employed to capture this cyclic motion, and valves were simulated in their fully open position to mimic the natural scenario, with in/outflow triggered at control planes away from the valves. Six turbulence models have been used, comprising three relevant to the low Reynolds number nature of this flow and three more intended to investigate different transport effects. In the first group, we consider the shear stress transport (SST) [Formula: see text] model in both its standard and transition-sensitive forms, and the 'laminar' model in which no turbulence model is used. In the second group, we compare the one equation Spalart-Almaras model, the standard two equation [Formula: see text] and the full Reynolds stress model (RSM). Following evaluation of spatial and temporal resolution requirements, results are compared with available experimental data. The model was operated at a systolic duration of 40% of the pumping cycle and a pumping rate of 86 BPM (beats per minute). Contrary to reasonable preconception, the 'transition' model, calibrated to incorporate additional physical modelling specifically for these flow conditions, was not noticeably superior to the standard form of the model. Indeed, observations of turbulent viscosity ratio reveal that the transition model initiates a premature increase of turbulence in this flow, when compared with

  10. Expert system for the diagnosis of the condition and performance of centrifugal pumps

    Energy Technology Data Exchange (ETDEWEB)

    Jantunen, E.; Vaehae-Pietilae, K.; Pesonen, K. [Technical Research Centre of Finland, Manufacturing Technology, Espoo (Finland)

    1997-12-31

    A brief description of the results of a study concerning the maintenance and downtime costs in Finnish pumping is given. The leakage of seals was found to be the fault that causes the highest downtime and maintenance costs. A small laboratory arrangement has been used to test the effectiveness of various condition monitoring methods. This information has been used in the development of a diagnostic expert system called CEPDIA, which can be used for diagnosing the condition of a pump and its components. The diagnosis is based on measuring results obtained from sensors and on information about maintenance actions carried out with the pump and its components. The principles of the CEPDIA expert system are described. A database is included in the system for handling and saving the measurement results, technical information on the pumps and maintenance actions carried out with the pumps. The diagnosis can also be based on vibration signature analysis, which is quite effective in determining which fault is the actual cause of malfunction of the pump or its components. CEPDIA can also be used to calculate of the efficiency of the electrical motor and the pump. CEPDIA has been tested in the diagnosis of 63 pumps. The average efficiency in pumping was less than 40 %, and more than 10 % of the pumps were pumping with less than 10 % efficiency. (orig.) 11 refs.

  11. Influence of Tip Clearance on Pressure Fluctuation in Low Specific Speed Mixed-Flow Pump Passage

    Directory of Open Access Journals (Sweden)

    Wenwu Zhang

    2017-01-01

    Full Text Available To explore the influence of tip clearance on pressure fluctuation in a low specific speed mixed-flow pump, tip clearances δ of 0.25 mm, 0.75 mm and 1.00 mm, along with no tip clearance, were selected. The reliability of the simulation was verified by comparison with the experimental data of external characteristics and fluctuation in the guide vane passage. Through ANSYS-CFX, MATLAB code and fast Fourier transform (FFT algorithm, pressure fluctuation characteristics in this pump were obtained. The results show that pressure fluctuation exists in all conditions due to the rotor-stator interaction. Under the no tip clearance and tip clearance conditions, the maximum fluctuation value was located near the guide inlet and impeller outlet, respectively. Clearance leakage had less influence on pressure fluctuation at the impeller inlet and central regions within a certain range of the clearance; beyond this range, fluctuations in the whole flow passage increased significantly, while the clearance variation had less effect on fluctuation in the guide vane. When the tip clearance value was 1.00 mm, pressure fluctuation of the shroud at the impeller inlet section suddenly increases, which was closely related to the obvious leakage vortexes and a larger low pressure area.

  12. FLOW DIRECTION OF PIEZOELEC-TRIC PUMP WITH NOZZLE/DIFFUSER-ELEMENTS

    Institute of Scientific and Technical Information of China (English)

    Zhang Jianhui; Xia Qixiao; Hong Zhen; Onuki Akiyoshi

    2004-01-01

    The piezoelectric pump with nozzle/diffuser-elements, which oscillating form differing from regular volumetric reciprocating or rotating pumps because there are nozzle/diffuser-elements substituted for regular valves, is a new type pump whose actuator is a piezoelectric ceramal part with verse piezoelectric effect.In recent year, piezoelectric pump is paid increasing attention to because it is an ideal candidate in application in such area as medical health, mechanical tools and micro-mechanism.The fundamental research on it, however, is still not made through.Focuses on the phenomenon of different directions of flow among Germany pump, Chinese pump and Swiss pump, which are all fitted with nozzle/diffuser-elements, and analyzes the cone angle of nozzle/diffuser-elements based on the flow equation of valve-less piezoelectric pump with nozzle/diffuser-elements.As a result, the concepts of diffuser loss coefficient and loss coefficient are introduced to explain these phenomena, from which a discussion is given on the optimization of the cone angle of nozzle/diffuser-element aiming at the maximum of pump flow.

  13. Passive magnetic bearing in the 3rd generation miniature axial flow pump-the valvo pump 2.

    Science.gov (United States)

    Okamoto, Eiji; Ishida, Yuya; Yano, Tetsuya; Mitamura, Yoshinori

    2015-06-01

    The new miniature axial flow pump (valvo pump 2) that is installed at the base of the ascending aorta consists of a six-phase stator, an impeller in which four neodymium magnets are incorporated, and passive magnetic bearings that suspend the impeller for axial levitation. The impeller is sustained by hydrodynamic force between the blade tip of the impeller and the inner housing of the stator. The passive magnetic bearing consists of a ring neodymium magnet and a columnar neodymium magnet. The ring neodymium magnet is set in the stationary side and the columnar neodymium magnet is incorporated in the impeller shaft. Both neodymium magnets are coaxially mounted, and the anterior and posterior passive magnetic bearings suspend the impeller by repulsion force against the hydrodynamic force that acts to move the impeller in the inflow port direction. The passive magnetic bearing was evaluated by a tensile test, and the levitation force of 8.5 N and stiffness of 2.45 N/mm was obtained. Performance of the axial flow pump was evaluated by an in vitro experiment. The passive magnetic bearing showed sufficient levitation capacity to suspend the impeller in an axial direction. In conclusion, the passive magnetic bearing is promising to be one of levitation technology for the third-generation axial flow blood pump.

  14. Water pumping and analysis of flow in burrowing zoobenthos - a short overview

    DEFF Research Database (Denmark)

    Riisgård, H. U.; Larsen, Poul Scheel

    2002-01-01

    Measurement of water pumping rates of burrowing animals is of crucial importance for the study of many processes both within and above the sea floor. This short review deals with water pumping and analysis of flow, including available techniques and bio-fluid mechanical theory, in burrowing deposit...

  15. 3-D Viscous Flow Analysis of a Mixed Flow Pump Impeller

    Directory of Open Access Journals (Sweden)

    Steven M. Miner

    2001-01-01

    Full Text Available This paper presents the results of a study using a coarse grid to analyze the flow in the impeller of a mixed flow pump. A commercial computational fluid dynamics code (FLOTRAN is used to solve the 3-D Reynolds Averaged Navier Stokes equations in a rotating cylindrical coordinate system. The standard k-ε turbulence model is used. The mesh for this study uses 26,000 nodes and the model is run on a SPARCstation 20. This is in contrast to typical analyses using in excess of 100,000 nodes that are run on a super computer platform. The smaller mesh size has advantages in the design environment. Stage design parameters are, rotational speed 1185 rpm, flow coefficient φ=0.116, head coefficient ψ=0.094, and specific speed 2.01 (5475 US. Results for the model include circumferentially averaged results at the leading and trailing edges of the impeller, and analysis of the flow field within the impeller passage. Circumferentially averaged results include axial and tangential velocities, static pressure, and total pressure. Within the impeller passage the static pressure and velocity results are presented on surfaces from the leading edge to the trailing edge, the hub to the shroud, and the pressure surface to the suction surface. Results of this study are consistent with the expected flow characteristics of mixed flow impellers, indicating that small CFD models can be used to evaluate impeller performance in the design environment.

  16. Characteristic analysis on the pressure fluctuation in the impeller of a low specific speed mixed flow pump

    Science.gov (United States)

    Zhang, W. W.; Yu, Z. Y.; Zhu, B. S.

    2016-05-01

    To explore the pressure fluctuation characteristics of a low speed specific speed mixed flow pump caused by rotor-stator interaction, the unsteady flow was simulated with CFX for the whole flow passage of a mixed flow pump with a specific speed of 148.8. The structured mesh of the computation domain was generated with ICEM CFD and TurboGrid, and mesh-independent analysis was done in the design condition. Through the comparison with the experiment data, the reliability of the simulation was verified. In different locations of the impeller passage, monitoring points were set. With Fast Fourier Transform (FFT), the characteristic analysis on the pressure fluctuation in the impeller passage was done for three flow rate conditions (0.75Qd, Qd, 1.25Qd). The results show that the pressure fluctuation amplitude increases from the inlet to the outlet. And the maximum values in different flow rates exist near the hub of the outlet; The pressure fluctuation is small in the design condition, but the largest in the small flow rate condition, accompanied by the secondary dominant frequencies with large amplitudes; In the small flow rate condition and design condition, the dominant frequency varies from the inlet to the outlet because the combine action of the impeller and guide vane; while in the large flow rate condition, the pressure fluctuation in the whole impeller passage is affected significantly by the guide vane, and the domain frequency is 8 times the rotational frequency of impeller. In addition, the change of pressure fluctuation from the pressure surface to the suction surface in the off-design conditions is investigated, and the results demonstrates that the intensity of the pressure fluctuation in the impeller passage is closely related with the impeller as well as the distribution of the vorticity and the pressure.

  17. Gas-lift pumps for flowing and purifying molten silicon

    Energy Technology Data Exchange (ETDEWEB)

    Kellerman, Peter L.; Carlson, Frederick

    2016-02-23

    The embodiments herein relate to a sheet production apparatus. A vessel is configured to hold a melt of a material and a cooling plate is disposed proximate the melt. This cooling plate configured to form a sheet of the material on the melt. A pump is used. In one instance, this pump includes a gas source and a conduit in fluid communication with the gas source. In another instance, this pump injects a gas into a melt. The gas can raise the melt or provide momentum to the melt.

  18. CFD SIMULATION OF 3D FLOW IN LARGE-BORE AXIAL-FLOW PUMP WITH HALF-ELBOW SUCTION SUMP

    Institute of Scientific and Technical Information of China (English)

    WANG Fu-jun; LI Yao-jun; CONG Guo-hui; WANG Wen-e; WANG Hai-song

    2006-01-01

    Numerical simulations of 3D turbulent flow in a large-bore axial-flow pump coupled with half-elbow suction sump were performed by using CFD approach. The numerical model and velocity and pressure distributions in entire flow passage were presented. The obvious backflow in half-elbow suction sump and strong flow nonuniformity at suction sump outlet were observed, whereas these phenomena were not observed in existing studies performed for a separate suction sump by either experimental or numerical approach. This result indicates that the interaction between half-elbow suction sump and impeller has significant effect on the flow distribution in the pump passage. The change of pump efficiency caused by the interaction was discussed.

  19. NaK flow control by electromagnetic pump of the SNAP-10A space nuclear reactor

    Energy Technology Data Exchange (ETDEWEB)

    Borges, Eduardo M.; Braz Filho, Francisco A.; Guimaraes, Lamartine N.F., E-mail: eduardo@ieav.cta.br, E-mail: fbraz@ieav.cta.br, E-mail: guimarae@ieav.cta.br [Instituto de Estudos Avancados (IEAv/DCTA), Sao Jose dos Campos, SP (Brazil)

    2013-07-01

    In the Institute for Advanced Studies (IEAv), were developed, successfully, the first two direct current electromagnetic pumps (DC EM pumps) of Brazil. The first was built with C-type magnet and coils; and the second, with Samarium-Cobalt permanent magnets, for magnetic field generation. Both were tested and performed quite satisfactory. The electromagnetic pump uses the Faraday principle, in which the interaction of the magnetic field and electric current generates the magneto-motive force, which produces the circulation of the fluid. This type of equipment may be used for controlling the liquid metal flow in nuclear space fast reactors. This paper shows the computer programs developed for design and evaluation of DC EM and electromagnetic thermoelectric (EMTE) pumps, the DC EM pump of Samarium-Cobalt magnets data to Mercury loop flow control, the EMTE pump of SNAP space nuclear reactor. It also compares the theoretical results to experimental data of NaK primary loop flow control by electromagnetic thermoelectric pump of the SNAP-10A space nuclear reactor, with satisfactory results, confirming the viability of the electromagnetic pumps evaluation scheme. (author)

  20. The flow field in a centrifugal pump with a large tongue gap and back blades

    Energy Technology Data Exchange (ETDEWEB)

    Cai, Jian Cheng [Zhejiang Normal University, Jinhua (China); Pan, Jie; Guzzomi, Andrew [The University of Western Australia, Crawley (Australia)

    2014-11-15

    In this paper, the unsteady 3-D turbulent flow fields in an end-suction centrifugal pump with a vaneless volute are studied numerically at three different rotation speeds. The unshrouded impeller of the pump, as a reduced diameter version of the original full-size impeller, has five backswept blades and five pump-out blades. The results show that the flow rate and pressure vary with the rotational speed according to the similarity law, and the normalized internal flow fields at all speeds are very similar. Due to the reduced impeller diameter, the pump efficiency is relatively low. Flows discharged from the front and back blade passages interfere with each other and swirling motion exists in the volute. The pressure fluctuations on the casing wall near the impeller outlet are extracted, and their spectra show that the component at the blade passing frequency was prominent. This study sheds some light on the characteristics of the internal unsteady flow of a centrifugal pump at different rotational speeds, and forms a basis for future study of flow induced pump vibration and noise.

  1. Variable flow controls of closed system pumps for energy savings in maritime power systems

    DEFF Research Database (Denmark)

    Su, Chun-Lien; Liao, Chi-Hsiang; Chou, Tso-Chu

    2016-01-01

    Pumps are extensively used in maritime industries as marine vessels utilize a wide range of pumps and pumping techniques to transfer and distribute all types of air and fluids. The electrical energy consumed by the various motors accounts for about 70% of a vessel’s total power consumption...... pumps on marine vessels. The existing problem of traditional control methods for closed system pumps is analyzed and a mathematical model for variable flow controls with the appropriate control settings is derived. The performance of the proposed method is demonstrated and verified through experimental...... and field tests of a practical auxiliary boiler feed water management system on a commercial vessel. It is proved that the proposed method can maintain constant water pressure for closed system pumps and provide an efficient way to measure energy savings and maintenance benefits. The results serve...

  2. Body position and activity, but not heart rate, affect pump flows in patients with continuous-flow left ventricular assist devices.

    Science.gov (United States)

    Muthiah, Kavitha; Gupta, Sunil; Otton, James; Robson, Desiree; Walker, Robyn; Tay, Andre; Macdonald, Peter; Keogh, Anne; Kotlyar, Eugene; Granger, Emily; Dhital, Kumud; Spratt, Phillip; Jansz, Paul; Hayward, Christopher S

    2014-08-01

    The aim of this study was to determine the contribution of pre-load and heart rate to pump flow in patients implanted with continuous-flow left ventricular assist devices (cfLVADs). Although it is known that cfLVAD pump flow increases with exercise, it is unclear if this increment is driven by increased heart rate, augmented intrinsic ventricular contraction, or enhanced venous return. Two studies were performed in patients implanted with the HeartWare HVAD. In 11 patients, paced heart rate was increased to approximately 40 beats/min above baseline and then down to approximately 30 beats/min below baseline pacing rate (in pacemaker-dependent patients). Ten patients underwent tilt-table testing at 30°, 60°, and 80° passive head-up tilt for 3 min and then for a further 3 min after ankle flexion exercise. This regimen was repeated at 20° passive head-down tilt. Pump parameters, noninvasive hemodynamics, and 2-dimensional echocardiographic measures were recorded. Heart rate alteration by pacing did not affect LVAD flows or LV dimensions. LVAD pump flow decreased from baseline 4.9 ± 0.6 l/min to approximately 4.5 ± 0.5 l/min at each level of head-up tilt (p heart rate, but they change significantly with body position and passive filling. Previously demonstrated exercise-induced changes in pump flows may be related to altered loading conditions, rather than changes in heart rate. Copyright © 2014 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.

  3. A new computational fluid dynamics method for in-depth investigation of flow dynamics in roller pump systems.

    Science.gov (United States)

    Zhou, Xiaoming; Liang, Xin M; Zhao, Gang; Su, Youchao; Wang, Yang

    2014-07-01

    Roller pumps are commonly used in circulatory assist devices to deliver blood, but the inherent high mechanical stresses (especially wall shear stress) may cause considerable damage to cells. Conventional experimental approaches to evaluate and reduce device-induced cell damage require considerable effort and resources. In this work, we describe the use of a new computational fluid dynamics method to more effectively study roller pump systems. A generalized parametric model for the fluid field in a typical roller pump system is presented first, and analytical formulations of the moving boundary are then derived. Based on the model and formulations, the dynamic geometry and mesh of the fluid field can be updated automatically according to the time-dependent roller positions. The described method successfully simulated the pulsing flow generated by the pump, offering a convenient way to visualize the inherent flow pattern and to assess shear-induced cell damage. Moreover, the highly reconfigurable model and the semiautomated simulation process extend the usefulness of the presented method to a wider range of applications. Comparison studies were conducted, and valuable indications about the detailed effects of structural parameters and operational conditions on the produced wall shear stress were obtained. Given the good consistency between the simulated results and the existing experimental data, the presented method displays promising potential to more effectively guide the development of improved roller pump systems which produce less mechanical damage to cells.

  4. Chief Joseph Kokanee Enhancement Project; Characterization of Pump Flow at the Grand Coulee Dam Pumping Station for Fish Passage, 2004-2005 Final Report.

    Energy Technology Data Exchange (ETDEWEB)

    Carlson, T.; Duncan, J.; Johnson, R.

    2005-03-01

    This report describes a study conducted by Pacific Northwest National Laboratory (PNNL) for the Bonneville Power Administration to characterize the conditions fish experience when entrained in pump flow at the Grand Coulee Dam. PNNL conducted field studies at Grand Coulee Dam in 2004 using the Sensor Fish to measure the acceleration and pressure conditions that might be experienced by fish that pass through pumps at Grand Coulee Dam's Pump-Generating Plant and are transported up into the feeder canal leading to Banks Lake. The probability that fish would be struck by the Pump-Generating Plant's new nine-bladed turbines was also estimated. Our measurements showed relatively low turbulence except in the immediate vicinity of the runner environment. The lowest and highest pressures experienced by the Sensor Fish were 6.4 and 155 psi (the pressure gauge saturated at 155 psi). The probability of strike was also calculated, based on the average length of hatchery-reared juvenile kokanee (land-locked sockeye). Strike probabilities ranged from 0.0755 for 2.36-inch fish to 0.3890 for 11.8-inch fish. The probability of strike estimates indicate that the majority (77%) of recently released hatchery kokanee would be carried through the test pump without being struck and most likely with low risk of injury resulting from pressure and turbulence exposure. Of the 23% that might be struck it is expected that 60% would arrive in Banks Lake without visible external injuries. Thus more than 90% of entrained fish could be expected to arrive in Banks Lake without significant injury, assuming that no kokanee were injured or killed by pressure exposure during passage.

  5. Flows in networks under fuzzy conditions

    CERN Document Server

    Bozhenyuk, Alexander Vitalievich; Kacprzyk, Janusz; Rozenberg, Igor Naymovich

    2017-01-01

    This book offers a comprehensive introduction to fuzzy methods for solving flow tasks in both transportation and networks. It analyzes the problems of minimum cost and maximum flow finding with fuzzy nonzero lower flow bounds, and describes solutions to minimum cost flow finding in a network with fuzzy arc capacities and transmission costs. After a concise introduction to flow theory and tasks, the book analyzes two important problems. The first is related to determining the maximum volume for cargo transportation in the presence of uncertain network parameters, such as environmental changes, measurement errors and repair work on the roads. These parameters are represented here as fuzzy triangular, trapezoidal numbers and intervals. The second problem concerns static and dynamic flow finding in networks under fuzzy conditions, and an effective method that takes into account the network’s transit parameters is presented here. All in all, the book provides readers with a practical reference guide to state-of-...

  6. NUMERICAL SIMULATION OF THE FLOW IN THE CENTRIFUGAL PUMP WITHIN VANE AND VANELESS DIFFUSER

    Directory of Open Access Journals (Sweden)

    K. Melih GÜLEREN

    2004-03-01

    Full Text Available In this study, the flow in a 5-bladed centrifugal pump within vaned and vaneless diffuser is analyzed numerically. The method contains of assumption as steady, incompressible and viscous flow solved according to 2-D Navier-Stokes equations relating finite volume technique. The pump used in this study runs at 890 rpm, its impeller diameter is approximately 20 cm and it has back-swept blade geometry. The jet-wake flow structures within the impeller and diffuser passages are investigated elaborately and in addition to this, the effects of vaned and vaneless diffuser of the pump are analyzed. The results are shown as velocity vectors, pressure and turbulent kinetic energy distributions in centrifugal pump, beside the performance curves. Moreover, the results are compared with available experimental data which is seen good agreement.

  7. Geohydrology of the Central Oahu, Hawaii, Ground-Water Flow System and Numerical Simulation of the Effects of Additional Pumping

    Science.gov (United States)

    Oki, Delwyn S.

    1998-01-01

    A two-dimensional, finite-difference, ground-water flow model was developed for the central Oahu flow system, which is the largest and most productive ground-water flow system on the island. The model is based on the computer code SHARP which simulates both freshwater and saltwater flow. The ground-water model was developed using average pumping and recharge conditions during the 1950's, which was considered to be a steady-state period. For 1950's conditions, model results indicate that 62 percent (90.1 million gallons per day) of the discharge from the Schofield ground-water area flows southward and the remaining 38 percent (55.2 million gallons per day) of the discharge from Schofield flows northward. Although the contribution of recharge from infiltration of rainfall and irrigation water directly on top of the southern and northern Schofield ground-water dams was included in the model, the distribution of natural discharge from the Schofield ground-water area was estimated exclusive of the recharge on top of the dams. The model was used to investigate the long-term effects of pumping under future land-use conditions. Future recharge was conservatively estimated by assuming no recharge associated with agricultural activities. Future pumpage used in the model was based on the 1995-allocated rates. Model results indicate that the long-term effect of pumping at the 1995-allocated rates will be a reduction of water levels from present (1995) conditions in all ground-water areas of the central Oahu flow system. In the Schofield ground-water area, model results indicate that water levels could decline about 30 feet from the 1995 water-level altitude of about 275 feet. In the remaining ground-water areas of the central Oahu flow system, water levels may decline from less than 1 foot to as much as 12 feet relative to 1995 water levels. Model results indicate that the bottoms of several existing deep wells in northern and southern Oahu extend below the model

  8. Temperature and Humidity Independent Control Research on Ground Source Heat Pump Air Conditioning System

    Science.gov (United States)

    Chen, G.; Wang, L. L.

    Taking green demonstration center building air conditioning system as an example, this paper presents the temperature and humidity independent control system combined with ground source heat pump system, emphasis on the design of dry terminal device system, fresh air system and ground source heat pump system.

  9. Simulation of the effects of seasonally varying pumping on intraborehole flow and the vulnerability of public-supply wells to contamination.

    Science.gov (United States)

    Yager, Richard M; Heywood, Charles E

    2014-09-01

    Public-supply wells with long screens in alluvial aquifers can produce waters of differing quality from different depths. Seasonal changes in quality are linked to seasonal changes in pumping rates that influence the distribution of flow into the well screens under pumping conditions and the magnitude and direction of intraborehole flow within the wells under ambient conditions. Groundwater flow and transport simulations with MODFLOW and MT3DMS were developed to quantify the effects of changes in average seasonal pumping rates on intraborehole flow and water quality at two long-screened, public-supply wells, in Albuquerque, New Mexico and Modesto, California, where widespread pumping has altered groundwater flow patterns. Simulation results indicate that both wells produce water requiring additional treatment to maintain potable quality in winter when groundwater withdrawals are reduced because less water is derived from parts of the aquifer that contain water requiring less treatment. Simulation results indicate that the water quality at both wells could be improved by increasing average winter-pumping rates to induce more lateral flow from parts of the aquifer that contain better quality water. Arsenic-bearing water produced by the Albuquerque well could be reduced from 55% to 45% by doubling average winter-pumping rate, while nitrate- and uranium-bearing water produced by the Modesto well could be reduced from 95% to 65% by nearly tripling the average winter-pumping rate. Higher average winter-pumping rates would also reduce the volume of intraborehole flow within both wells and prevent the exchange of poor quality water between shallow and deep parts of both aquifers.

  10. Cooperative Suction by Vertical Capillary Array Pump for Controlling Flow Profiles of Microfluidic Sensor Chips

    Directory of Open Access Journals (Sweden)

    Emi Tamechika

    2012-10-01

    Full Text Available A passive pump consisting of integrated vertical capillaries has been developed for a microfluidic chip as an useful component with an excellent flow volume and flow rate. A fluidic chip built into a passive pump was used by connecting the bottoms of all the capillaries to a top surface consisting of a thin layer channel in the microfluidic chip where the thin layer channel depth was smaller than the capillary radius. As a result the vertical capillaries drew fluid cooperatively rather than independently, thus exerting the maximum suction efficiency at every instance. This meant that a flow rate was realized that exhibited little variation and without any external power or operation. A microfluidic chip built into this passive pump had the ability to achieve a quasi-steady rather than a rapidly decreasing flow rate, which is a universal flow characteristic in an ordinary capillary.

  11. Comparison of Modified Chandler, Roller Pump, and Ball Valve Circulation Models for In Vitro Testing in High Blood Flow Conditions: Application in Thrombogenicity Testing of Different Materials for Vascular Applications

    Directory of Open Access Journals (Sweden)

    Wim van Oeveren

    2012-01-01

    We concluded that the Hemobile minimally affects blood and could be adjusted to high blood flows, simulating arterial shear stress. The Hemobile was used to measure hemocompatibility of graft material and showed Dyneema Purity UHMWPE fiber in many ways more hemocompatible than ePTFE and PET.

  12. Hemolysis research of implantable axial flow pump for two -step heart transplantation in children

    Directory of Open Access Journals (Sweden)

    O. Yu. Dmitrieva

    2017-01-01

    Full Text Available Introduction. One of the main indicators characterizing mechanical circulatory support devices (artificial valve, implantable pumps, etc. is trauma of blood cells. Therefore, while developing new pumps, one of the key studies in vitro is to evaluate blood hemolysis. For an objective hemolysis analysis of pump it is required to create a standardized methodology of hemolysis studies. The object of the study in this paper is implantable axial pump DON for two-step heart transplantation in children.The aim of study is to develop a standardized methodology of hemolysis studies of blood pumps and to conduct research of pediatric axial pump DON.Materials and methods. To conduct hemolysis research we created a mock circulatory system consisting of a reservoir placed in water bath maintaining a constant working fluid (blood temperature, hydrodynamic resistance, connecting tubes, ports for blood sampling and pressure and flow measurement systems, and research pump. Test method is to estimate levels of free hemoglobin pHb obtained by blood samples during pump working in operating mode (for pediatric pump: blood flow 2.5 l/min, pressure difference 80 mmHg. Using the data obtained the standardized indices of hemolysis NIH and MIH are calculated based on pHb values, hematocrit, total hemoglobin, blood flow and working pump time.Results. We developed and realized a standardized methodology of hemolysis research by which we evaluated hemolysis of pediatric axial pump. The results of hemolysis tests allowed us to optimize the design of DON. Obtained values of hemolysis of the latest version of pediatric pump DON-3 have shown that they do conform to the requirements of minimum blood injury and it allows us to proceed to the next step of pediatric pump research – animal experiments.Conclusion. Developed methods and evaluation tools of hemolysis allow us to provide objective information on one of the most important indicators of developing

  13. 轴流式血泵流场CFD仿真%Flow field CFD analysis of axial flow blood pump

    Institute of Scientific and Technical Information of China (English)

    谢雄; 谭建平

    2014-01-01

    In the development of axial flow blood pump,the arterial partial flow field may produce an area with very low flow shear rate,so it is necessary to consider the non-Newtonian charac-teristics of blood fluid.In this paper,a model of axial flow blood pump was established,and flow and rotate-speed’s impacts on the inlet and outlet of the flow field in the blood pump were ana-lyzed through Computational Fluid Dynamics (CFD)simulation,as wel as the influence of the guide vane on the flow field.By the pump water experiment of the designed blood pump,its out-put flow and pressure were measured;the results show that the designed blood pump is consist-ent on the law with the simulation.%在轴流式血泵的研发过程中,动脉局部流场中可能产生流动剪切率非常低的区域,因此有必要考虑血液的非牛顿特性。建立了轴流式血泵模型,通过CFD仿真分析得到血泵转速和流量的变化对血泵出入口压力分布和速度分布的影响,并采用水和甘油(2∶1)的混合流体替代血液,对设计的血泵进行驱动实验,测量了轴流式血泵输出流量和压力参数。结果表明:所设计的血泵在规律上和仿真是相符的。

  14. Computational fluid dynamics of gap flow in a biocentrifugal blood pump.

    Science.gov (United States)

    Chua, Leok Poh; Song, Guoliang; Yu, Simon Ching Man; Lim, Tau Meng

    2005-08-01

    The centrifugal blood pump with a magnetically suspended impeller has shown its superiority as compared to other artificial heart pumps. However, there is still insufficient understanding of fluid mechanics related issues in the clearance gap. The design nature of the pump requires sufficient washout in the clearance between the impeller and the stationary pump housing inner surface. In this study, numerical simulations were carried out to investigate the flow fields in the gap of the Kyoto-NTN centrifugal blood pump. The flow patterns in the gap region of the blood pump were presented and regions of high and low velocity were identified. It was found that the radial velocity of the blood in the gap was closely related to the pressure distribution at the exit of the impeller, both the highest pressure gradient and the highest radial velocity in the gap occurred at an angular position of 170 degrees . The mass flow rate in the gap was estimated to be 25.2% of the pump outflow, which is close to the measurement results of a five times enlarged test pump. The wall shear stresses on the gap surface were found to be over 21 Pa and below 300 Pa, which is correspondingly higher than the threshold of thrombi formation and is lower than the shearing threshold of red blood cells. Comparison of the 1 : 1 simulation model with the measurement results on a five times enlarged test pump indicates that there are some differences in the resulting radial velocity distributions in the gap and thus the washout mechanism. Two symmetrical high washout regions at both the cutwater and splitter plate were observed in the simulation instead of a single washout region at the splitter plate found in the experimental study. This may be due to the scaling effect of the enlarged test pump; also the medium used in the experiment is different from the simulation.

  15. Interaction of impeller and guide vane in a series-designed axial-flow pump

    Science.gov (United States)

    Kim, S.; Choi, Y. S.; Lee, K. Y.; Kim, J. H.

    2012-11-01

    In this paper, the interaction of the impeller and guide vane in a series-designed axial-flow pump was examined through the implementation of a commercial CFD code. The impeller series design refers to the general design procedure of the base impeller shape which must satisfy the various flow rate and head requirements by changing the impeller setting angle and number of blades of the base impeller. An arc type meridional shape was used to keep the meridional shape of the hub and shroud with various impeller setting angles. The blade angle and the thickness distribution of the impeller were designed as an NACA airfoil type. In the design of the guide vane, it was necessary to consider the outlet flow condition of the impeller with the given setting angle. The meridional shape of the guide vane were designed taking into consideration the setting angle of the impeller, and the blade angle distribution of the guide vane was determined with a traditional design method using vane plane development. In order to achieve the optimum impeller design and guide vane, three-dimensional computational fluid dynamics and the DOE method were applied. The interaction between the impeller and guide vane with different combination set of impeller setting angles and number of impeller blades was addressed by analyzing the flow field of the computational results.

  16. Numerical simulation of dynamic flow characteristics in a centrifugal water pump with three-vaned diffuser

    Directory of Open Access Journals (Sweden)

    Zhi-Jun Shuai

    2015-08-01

    Full Text Available The complex three-dimensional turbulent flow field in a centrifugal water pump with three asymmetrical diffusers was numerically simulated. The characteristics of pressure and force fluctuations inside the model pump were investigated. Fast Fourier transformation was performed to obtain the spectra of pressure and force fluctuations. It indicates that the dominant frequency of pressure fluctuations is the blade passing frequency in all the sub-domains inside the pump and the first blade passing frequency energy (first order of blade passing frequency is the most significant. The dominant frequency of pressure fluctuations at the location of diffuser outlet is featured by low frequency (less than 1 Hz, which may be due to the locally generated eddy structures. Besides, the dominant frequency force fluctuations on the impeller blades are also the blade passing frequency. The existence of the three asymmetrical diffusers has damping effect on the pressure fluctuation amplitude and energy amplitude of pressure fluctuations in the diffuser domain dramatically, which indicates that the diffusers can effectively control the hydraulically excited vibration in the pump. Besides, the prediction of the dominant frequency of pressure fluctuations inside the pump can help to utilize the pump effectively and to extend the pump life. The main findings of this work can provide prediction of the pump performance and information for further optimal design of centrifugal pumps as well.

  17. Influence of blade thickness on transient flow characteristics of centrifugal slurry pump with semi-open impeller

    Science.gov (United States)

    Tao, Yi; Yuan, Shouqi; Liu, Jianrui; Zhang, Fan; Tao, Jianping

    2016-10-01

    As the critical component, the impellers of the slurry pumps usually have blades of a large thickness. The increasing excretion coefficient of the blades affects the flow in the impeller resulting in a relatively higher hydraulic loss, which is rarely reported. In order to investigate the influence of blade thickness on the transient flow characteristics of a centrifugal slurry pump with a semi-open impeller, transient numerical simulations were carried out on six impellers, of which the meridional blade thickness from the leading edge to trailing edge varied from 5-10 mm, 5-15 mm, 5-20 mm, 10-10 mm, 10-15 mm, and 10-20 mm, respectively. Then, two of the six impellers, namely cases 4 and 6, were manufactured and experimentally tested for hydraulic performance to verify the simulation results. Results of these tests agreed reasonably well with those of the numerical simulation. The results demonstrate that when blade thickness increases, pressure fluctuations at the outlet of the impeller become severe. Moreover, the standard deviation of the relative velocity in the middle portion of the suction sides of the blades decreases and that at the outlet of the impeller increases. Thus, the amplitude of the impeller head pulsation for each case increases. Meanwhile, the distribution of the time-averaged relative flow angle becomes less uniform and decreases at the outlet of the impeller. Hence, as the impeller blade thickness increases, the pump head drops rapidly and the maximum efficiency point is offset to a lower flow rate condition. As the thickness of blade trailing edge increases by 10 mm, the head of the pump drops by approximately 5 m, which is approximately 10 % of the original pump head. Futhermore, it is for the first time that the time-averaged relative flow angle is being considered for the analysis of transient flow in centrifugal pump. The presented work could be a useful guideline in engineering practice when designing a centrifugal slurry pump with thick

  18. Hydrodynamic Analysis of the Flow Field Induced by a Symmetrical Suction Elbow at the Pump Inlet

    Science.gov (United States)

    Muntean, S.; Bosioc, A. I.; Drăghici, I.; Anton, L. E.

    2016-11-01

    The paper investigates the hydrodynamic field generated by the symmetrical suction elbow at the pump impeller inlet. The full three-dimensional turbulent numerical investigation of the flow in the symmetrical suction elbow is performed using FLUENT then the flow non-uniformity generated by it is numerically computed. The numerical results on the annular cross section are qualitatively and quantitatively validated against LDV data. A good agreement between numerical results and experimental data is obtained on this cross section located downstream to the suction elbow and upstream to the pump impeller. The hydrodynamic flow structure with four vortices is identified plotting the vorticity field. The largest values of the vorticity magnitude are identified in the center of both vortices located behind the shaft. The vortex core location is plotted on four annular cross sections located along to the cylindrical part between the suction elbow and the pump inlet. Also, the three-dimensional distribution of the vortex core filaments is visualized and extracted. The shapes of vortex core filaments located behind the pump shaft agree well with its visualization performed on the test rig. As a result, the three-dimensional complex geometry of the suction elbow and the pump shaft are identified as the main sources of the flow non-uniformity at the pump inlet.

  19. The simulation of multiphase flow field in implantable blood pump and analysis of hemolytic capability

    Institute of Scientific and Technical Information of China (English)

    LI Tie-yan; YE Liang; HONG Fang-wen; LIU Deng-cheng; FAN Hui-min; LIU Zhong-min

    2013-01-01

    The numerical simulation of the axial flow impeller blood pump NIVADIII is carried out by using a CFD multiphase flow model.The hydrodynamic performance of the pump and the flow field in the pump are analyzed,and the shear stress distribution is obtained.A hemolytic prediction model based on the shear stress is built based on the calculation results,and it can be used for quantitative predictions of the hemolytic behavior of a blood pump.Hemolysis tests in vitro were performed 6 times with fresh bovine blood.At each time,the flow of the pump NIVADIII is 5 L/min and the outflow tract pressure is 100 mmHg.According to the tests,the plasma free hemoglobin (FHB) content and the hematocrit (HCT) are measured after 0 s,0.5 s,1 s,1.5 s,...4 s.At the end of each experiment Normal Index of Hemolysis (NIH) of NIVADIII is calculated.The average of NIH is 0.0055 g/100L,almost identical with that obtained from the hemolytic prediction model.This method can be applied in the selection stage of a blood pump.

  20. Numerical simulation on the "S" characteristics and pressure fluctuation of reduced pump-turbine at start-up condition

    Science.gov (United States)

    Liu, D. M.; Zheng, J. S.; Wen, G. Z.; Zhao, Y. Z.; Shi, Q. H.

    2012-11-01

    The performance of a reversible pump turbine with S-shaped characteristics is of great importance to the transition processes such as start-up and load rejection. In order to improve the "S" characteristics of reduced pump-turbine, several MGV (misaligned guide vane) schemes are calculated. The SST (shear stress turbulence) model is added to the N-S (Navier-strokes) governing equation. In order to predict the S-shaped curve accurately and develop a reliable tool for design improvement, the "S" characteristic is investigated in a whole pump-turbine including spiral casing, stay vanes, guide vanes, runner and draft tube. To validate the scheme reasonable, the mesh independent is tested. Comparison of unit discharge and unit speed performance showed that good correspondence is obtained between experimental data and calculated results. The "S shape" of reduced pump-turbine is eliminated with MGV schemes. Based on this, internal flow analysis is carried out adopting six typical MGV schemes at the same working condition. Through the calculation, we find that, first the pressure fluctuation is different between the guide vane and runner among the five MGV schemes, second the pressure fluctuation amplitude of MGV schemes D (4*35° and 16*6° average installed) is smallest, third the main frequency is the blade passing frequency and guide vane passing frequency at vane-less space and head cover, respectively. The conclusion is the "S shape" of pump-turbine can be improved with the average installed scheme.

  1. Chemiluminometric determination of captopril in a multi-pumping flow system.

    Science.gov (United States)

    Rodrigues, S Sofia M; Santos, João L M

    2012-07-15

    In this work, a simple, versatile and fully automated analytical methodology for the chemiluminometric determination of captopril - an angiotensin II-converting-enzyme (ACE) inhibitor - in pharmaceutical formulations, is proposed. The developed methodology was based on the enhancement by captopril of the chemiluminescence emission of tris(2,2'-bipyridyl)ruthenium(II). In sulphuric acid medium tris(2,2'-bipyridyl)ruthenium(II) was oxidized by cerium(IV) and converted into a reactive oxidant specie [Ru(bpy)(3)](3+), which was subsequently reduced with captopril in order to yield a significant enhancement of the original chemiluminescence emission that was directly related to captopril concentration. The analytical process was implemented by resorting to an automated multi-pumping flow system (MPFS) that enabled the establishment of multiple reaction interfaces, which, in combination with the created pulsed flowing stream assured a fast and reproducible sample/reagent mixing and reaction development essential to guarantee the generation and subsequent measurement of the short-lived species involved in the chemiluminescent process. The developed system employed three solenoid micro-pumps as the only flow manifold active components. These assured the insertion, propelling and commuting of all solutions. The automatic actuation of the solenoid micro-pumps provided an easily programmed, operated and controlled analytical flow system, exhibiting high versatility, efficiency and compactness at a low cost. Under the optimized experimental conditions, the proposed method allowed the determination of captopril for concentrations between 2×10(-3) and 1.5×10(-1)mmolL(-1) (r=0.9996, n=6) and a sampling frequency of about 58 determinations per hour, producing 620μL of waste per determination. The results obtained for pharmaceutical formulations were statistically comparable to those provided by the reference procedure with a relative deviation between -2.32 and 1.39%. The

  2. Numerical analysis on the cavitation and unsteady flow in a scroll hydraulic pump

    Science.gov (United States)

    Sun, S. H.; Guo, P. C.; Huang, Y.; Zuo, J. L.; Luo, X. Q.

    2016-05-01

    This paper presents numerical analysis of unsteady flow in a scroll hydraulic pump to discover its flow mechanism. The dynamic mesh model has to be used to simulate the flow field unsteadily. The unsteady flow patterns and pressure distributions in the suction, squeezing and discharge chamber are analysed. The suction process continues until the crank angle reaches the 320 degree. Then the pressure in the chamber rises instantaneously, and the fluid begins to flow out from the chamber. Because of the high pressure difference at the clearance, the jet flow and the vortex appear, and the large flow losses generates with them. In addition, the velocity and static pressure distribution in the two symmetry crescent suction chamber is different remarkably. One reason is that the location of suction port cannot be set symmetrically for the simplification of the pump structure. Another reason for that is the fluid is impelled by different part of the orbiting scroll. The asymmetric pressure distribution will result in the extra force on the scroll. The cavitation generates at the negative pressure region. Therefore, the unsteady simulation shows some important phenomena. The structure of the scroll pump need to be optimized to reduce the maximum pressure, weaken the jet flow, vortex and the uneven pressure distribution to ensure the pump working safely and efficiently.

  3. Finite element calculations and experimental verification of the unsteady potential flow in a centrifugal volute pump

    NARCIS (Netherlands)

    Badie, R.; Jonker, J.B.; Braembussche, van den R.A.

    1994-01-01

    In this paper we present a finite-element-based methode for the calculation of the unsteady potential flow in rotor/stator configurations. A numerical algorithm was developed to calculate the two-dimensional flow through a centrifugal volute pump, taking into account the width variation of the volut

  4. Flow to partially penetrating wells in unconfined heterogeneous aquifers: Mean head and interpretation of pumping tests

    Science.gov (United States)

    Dagan, G.; Lessoff, S. C.

    2011-06-01

    A partially penetrating well of length Lw and radius Rw starts to pump at constant discharge Qw at t = 0 from an unconfined aquifer of thickness D. The aquifer is of random and stationary conductivity characterized by KG (geometric mean), σY2 (log conductivity variance), and I and Iv (the horizontal and vertical integral scales). The flow problem is solved under a few simplifying assumptions commonly adopted in the literature for homogeneous media: Rw/Lw ≪ 1, linearization of the free surface condition, and constant drainable porosity n. Additionally, it is assumed that Rw/I and the associated water table equation. The main result of the analysis is that the flow domain can be divided into three zones for : (1) the neighborhood of the well R ≪ I, where = (Qw/LwKA)h0(R, z, tKefuv/nD), with h0 being the zero-order solution pertaining to a homogeneous and isotropic aquifer, KA being the conductivity arithmetic mean, and Kefuv being the effective vertical conductivity in mean uniform flow, (2) an exterior zone R ⪆ I in which ?H? = (Qw/LwKefuh)h0(R?, z, tKefuv/nD), with Kefuh being the horizontal effective conductivity, and (3) an intermediate zone in which the solution requires a few numerical quadratures, not carried out here. The application to pumping tests reveals that identification of the aquifer parameters for homogeneous and anisotropic aquifers by commonly used methods can be applied for the drawdown measured in an observation well of length Low?Iv (to ensure exchange of space and ensemble head averages) in the second zone in order to identify Kefuh, Kefuv, and n. In contrast, the use of the drawdown in the well (first zone) leads to an overestimation of Kefuh by the factor KA/Kefuh.

  5. Effects of upstream dams versus groundwater pumping on stream temperature under varying climate conditions

    National Research Council Canada - National Science Library

    John C. Risley; Jim Constantz; Hedeff Essaid; Stewart Rounds

    2010-01-01

      The relative impact of a large upstream dam versus in-reach groundwater pumping on stream temperatures was analyzed for humid, semiarid, and arid conditions with long dry seasons to represent typical...

  6. Numerical study of unsteady flows with cavitation in a high-speed micro centrifugal pump

    Science.gov (United States)

    Li, Yeqiang; Yuan, Shiwei; Lai, Huanxin

    2017-02-01

    The unsteady flows caused by the interaction between the impeller and the volute in a high-speed micro centrifugal pump are numerically studied. The internal flows of both with and without cavitations are analyzed using the CFX. The characteristics of unsteady pressure on the blade surfaces and the symmetric plane of the volute are presented and compared. The results show that the amplitudes of pressure fluctuations of critical cavitation on the blade pressure surface (PS) are bigger as compared with those at the non-cavitation condition, but on the suction surface (SS), the situation is on the contrary. When cavitation occurs, reduction of load in the impeller is a result. In the present study, such reduction of load is observed mainly on the first half of the blades. Pressure fluctuations at five monitoring points, denoted by WK1 to WK5 in the volute, are also analyzed. No matter at the critical cavitation or at the non-cavitation conditions, the monitored pressure fluctuations are at the same frequencies, which equal to the blade passing frequency (BPF) and its multiples. However, the amplitudes of the fluctuations at critical cavitation condition are considerably stronger, as compared with those for without cavitation.

  7. Design and optimization of a large flow rate booster pump in SWRO energy recovery system

    Science.gov (United States)

    Lai, Z. N.; Wu, P.; Wu, D. Z.; Wang, L. Q.

    2013-12-01

    Seawater reverse osmosis (SWRO) is a high energy-consumption industry, so energy efficiency is an important issue. Energy recovery systems, which contain a pressure exchanger and a booster pump, are widely used in SWRO plants. As a key part of energy recovery system, the difficulty of designing booster pumps lies in high inlet pressure, high medium causticity and large flow rate. High inlet pressure adds difficulties to seal design, and large flow rate and high efficiency requirement bring high demand for hydraulic design. In this paper, a 625 m3/h booster pump is designed and optimized according to the CFD (Computational Fluid Dynamics) simulation results. The impeller and volute is well designed, a new type of high pressure mechanical seal is applied and axial force is well balanced. After optimization based on blade redesign, the efficiency of the pump was improved. The best efficiency reaches more than 85% at design point according to the CFD simulation result.

  8. Investigation of Flow Through Centrifugal Pump Impellers Using Computational Fluid Dynamics

    Directory of Open Access Journals (Sweden)

    Weidong Zhou

    2003-01-01

    Full Text Available With the aid of computational fluid dynamics, the complex internal flows in water pump impellers can be well predicted, thus facilitating the design of pumps. This article describes the three-dimensional simulation of internal flow in three different types of centrifugal pumps (one pump has four straight blades and the other two have six twisted blades. A commercial three-dimensional Navier-Stokes code called CFX, with a standard k–ε two-equation turbulence model was used to simulate the problem under examination. In the calculation, the finite-volume method and an unstructured grid system were used for the solution procedure of the discretized governing equations for this problem.

  9. Modeling of static and flowing-gas diode pumped alkali lasers

    Science.gov (United States)

    Barmashenko, Boris D.; Auslender, Ilya; Yacoby, Eyal; Waichman, Karol; Sadot, Oren; Rosenwaks, Salman

    2016-03-01

    Modeling of static and flowing-gas subsonic, transonic and supersonic Cs and K Ti:Sapphire and diode pumped alkali lasers (DPALs) is reported. A simple optical model applied to the static K and Cs lasers shows good agreement between the calculated and measured dependence of the laser power on the incident pump power. The model reproduces the observed threshold pump power in K DPAL which is much higher than that predicted by standard models of the DPAL. Scaling up flowing-gas DPALs to megawatt class power is studied using accurate three-dimensional computational fluid dynamics model, taking into account the effects of temperature rise and losses of alkali atoms due to ionization. Both the maximum achievable power and laser beam quality are estimated for Cs and K lasers. The performance of subsonic and, in particular, supersonic DPALs is compared with that of transonic, where supersonic nozzle and diffuser are spared and high power mechanical pump (needed for recovery of the gas total pressure which strongly drops in the diffuser), is not required for continuous closed cycle operation. For pumping by beams of the same rectangular cross section, comparison between end-pumping and transverse-pumping shows that the output power is not affected by the pump geometry, however, the intensity of the output laser beam in the case of transverse-pumped DPALs is strongly non-uniform in the laser beam cross section resulting in higher brightness and better beam quality in the far field for the end-pumping geometry where the intensity of the output beam is uniform.

  10. Numerical Simulation of 3D Solid-Liquid Turbulent Flow in a Low Specific Speed Centrifugal Pump: Flow Field Analysis

    Directory of Open Access Journals (Sweden)

    Baocheng Shi

    2014-06-01

    Full Text Available For numerically simulating 3D solid-liquid turbulent flow in low specific speed centrifugal pumps, the iteration convergence problem caused by complex internal structure and high rotational speed of pump is always a problem for numeral simulation researchers. To solve this problem, the combination of three measures of dynamic underrelaxation factor adjustment, step method, and rotational velocity control means according to residual curves trends of operating parameters was used to improve the numerical convergence. Numeral simulation of 3D turbulent flow in a low specific speed solid-liquid centrifugal pump was performed, and the results showed that the improved solution strategy is greatly helpful to the numerical convergence. Moreover, the 3D turbulent flow fields in pumps have been simulated for the bottom ash-particles with the volume fraction of 10%, 20%, and 30% at the same particle diameter of 0.1 mm. The two-phase calculation results are compared with those of single-phase clean water flow. The calculated results gave the main region of the abrasion of the impeller and volute casing and improve the hydraulic design of the impeller in order to decrease the abrasion and increase the service life of the pump.

  11. Continuum model for Couette-Poiseuille flow in a drag molecular pump

    CERN Document Server

    Skovorodko, P A

    2004-01-01

    A continuum one-dimensional model of the plane Couette-Poiseuille flow is developed to describe the pressure distribution in a drag stage of molecular pump of either the Gaede or Holweck type. In spite of its simplicity and approximate nature the model provides a good qualitative representation of the drag pump operation in the whole range of the regimes from the continuum to free molecular ones.

  12. Suppression of Performance Curve Instability of an Axial-Flow Pump by Using a Double-Inlet-Nozzle

    Directory of Open Access Journals (Sweden)

    P. Pérez Flores

    2008-01-01

    Full Text Available It has been shown that the sudden decrease of pump head in an axial flow pump caused by stall can be overcome by means of casing treatment. Flat axial grooves in front of the impeller break the swirl of the near-casing backflow. The disadvantage of this method is strong cavitation at the inlet of the grooves for flow rates below the stall point. In this paper another improved method to stabilize the performance curve will be presented, using a double-inlet-nozzle. At the onset of stall the initial near-casing backflow with its high swirl is lead off into the gap between both nozzles. At design conditions this double-inlet-nozzle is working as an injector, supporting the near-casing-inflow. The function of the double-inlet-nozzle is demonstrated by PIV-measurements.

  13. Noninvasive average flow and differential pressure estimation for an implantable rotary blood pump using dimensional analysis.

    Science.gov (United States)

    Lim, Einly; Karantonis, Dean M; Reizes, John A; Cloherty, Shaun L; Mason, David G; Lovell, Nigel H

    2008-08-01

    Accurate noninvasive average flow and differential pressure estimation of implantable rotary blood pumps (IRBPs) is an important practical element for their physiological control. While most attempts at developing flow and differential pressure estimate models have involved purely empirical techniques, dimensional analysis utilizes theoretical principles of fluid mechanics that provides valuable insights into parameter relationships. Based on data obtained from a steady flow mock loop under a wide range of pump operating points and fluid viscosities, flow and differential pressure estimate models were thus obtained using dimensional analysis. The algorithm was then validated using data from two other VentrAssist IRBPs. Linear correlations between estimated and measured pump flow over a flow range of 0.5 to 8.0 L/min resulted in a slope of 0.98 ( R(2) = 0.9848). The average flow error was 0.20 +/- 0.14 L/min (mean +/- standard deviation) and the average percentage error was 5.79%. Similarly, linear correlations between estimated and measured pump differential pressure resulted in a slope of 1.027 ( R(2) = 0.997) over a pressure range of 60 to 180 mmHg. The average differential pressure error was 1.84 +/- 1.54 mmHg and the average percentage error was 1.51%.

  14. Rotordynamic forces generated by discharge-to-suction leakage flows in centrifugal pumps

    Institute of Scientific and Technical Information of China (English)

    LIU Quan-zhong; WANG Hong-jie; LIU Zhan-sheng

    2009-01-01

    In order to investigate the flow-induced vibration in the shroud passage of centrifugal pump and pre-dict rotordynamic forces of centrifugal pump rotor system,an analysis of rotordynamic forces arising from shrou-ded centnlugal pump is presented.CFD techniques were utilized to analyze the full three-dimensional viscous,primary/secondary flow field in a centrifugal pump impeller to determine rotordynamic forces. Multiple quasi-steady solutions of an eccentric three-dimensional model at different whirl frequency ratios yielded the rotordy-namic forces. The skew-symmetric stiffness,damping,and mass matrices were obtained by second-order least-squares analysis.Simulation of the coupled primary/secondary flow field was conducted,and the complex flow characteristcs.in the flow field of a shroud passage were achieved including the mean velocity and pressure,as well as the eddy in a large scale of flow field due to viscosity.The rotordynamic force coefficients were calculat-ed,and the results were in good agreement with those of experiment except for the direct inertial coefficient without the consideration of whirling forces from the impeller primary flow passage.

  15. EFFECTS OF SPLITTER BLADES ON THE LAW OF INNER FLOW WITHIN CENTRIFUGAL PUMP IMPELLER

    Institute of Scientific and Technical Information of China (English)

    YUAN Shouqi; ZHANG Jinfeng; YUAN Jianping; HE Youshi; FU Yuedeng

    2007-01-01

    Analysis on the inner flow field of a centrifugal pump impeller with splitter blades is carried out by numerical simulation. Based on this analysis, the principle of increasing pump head and efficiency are discussed. New results are obtained from the analysis of turbulence kinetic energy and relative velocity distribution: Firstly, unreasonable length or deviation design of the splitter blades may cause great turbulent fluctuation in impeller channel, which has a great effect on the stability of impeller outlet flow; Secondly, it is found that the occurrence of flow separation can be decreased or delayed with splitter blades from the analysis of blade loading; Thirdly, the effect of splitter blades on reforming the structure of "jet-wake" is explained from the relative velocity distribution at different flow cross-sections, which shows the flow process in the impeller. The inner flow analysis verifies the results of performance tests results and the PIV test.

  16. Pump-and-treat optimization using analytic element method flow models

    Science.gov (United States)

    Matott, L. Shawn; Rabideau, Alan J.; Craig, James R.

    2006-05-01

    Plume containment using pump-and-treat (PAT) technology continues to be a popular remediation technique for sites with extensive groundwater contamination. As such, optimization of PAT systems, where cost is minimized subject to various remediation constraints, is the focus of an important and growing body of research. While previous pump-and-treat optimization (PATO) studies have used discretized (finite element or finite difference) flow models, the present study examines the use of analytic element method (AEM) flow models. In a series of numerical experiments, two PATO problems adapted from the literature are optimized using a multi-algorithmic optimization software package coupled with an AEM flow model. The experiments apply several different optimization algorithms and explore the use of various pump-and-treat cost and constraint formulations. The results demonstrate that AEM models can be used to optimize the number, locations and pumping rates of wells in a pump-and-treat containment system. Furthermore, the results illustrate that a total outflux constraint placed along the plume boundary can be used to enforce plume containment. Such constraints are shown to be efficient and reliable alternatives to conventional particle tracking and gradient control techniques. Finally, the particle swarm optimization (PSO) technique is identified as an effective algorithm for solving pump-and-treat optimization problems. A parallel version of the PSO algorithm is shown to have linear speedup, suggesting that the algorithm is suitable for application to problems that are computationally demanding and involve large numbers of wells.

  17. Optimal main pulse angle for different preplasma conditions in transient collisionally pumped x-ray lasers.

    Science.gov (United States)

    Ursescu, Daniel; Zielbauer, Bernhard; Kuehl, Thomas; Neumayer, Paul; Pert, Geoff

    2007-04-01

    The effects of the incidence angle of the main pump (MP) pulse in non-normal pumping geometry and the influence of the MP duration are investigated experimentally and theoretically for a transient collisionally pumped (TCE) x-ray laser in Ni-like Zr at 45 degrees and 72 degrees incidence angle on the target. The way they transfer to the x-ray laser output depends on the preplasma conditions, most notably on the average ionization distribution at the arrival of the MP. Moreover, contrary to previous grazing incidence pumping results, it is found that the shortest attainable MP maximizes the output. Modeling of the experimental results is performed with EHYBRID code. The results are important for scaling high repetition-rate non-normal incidence pumped lasers to sub- 10nm wavelengths.

  18. Flow ripple reduction of an axial piston pump by a combination of cross-angle and pressure relief grooves: Analysis and optimization

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Bing; Ye, Shaogan; Zhang, Junhui; Zhang, Chunfeng [Zhejiang University, Hangzhou (China)

    2016-06-15

    This paper investigates the potential of flow ripple reduction of an axial piston pump by a combination of cross-angle and pressure relief grooves. A dynamic model is developed to analyze the pumping dynamics of the pump and validated by experimental results. The effects of cross-angle on the flow ripples in the outlet and inlet ports, and the piston chamber pressure are investigated. The effects of pressure relief grooves on the optimal solutions obtained by a multi-objective optimization method are identified. A sensitivity analysis is performed to investigate the sensitivity of cross-angle to different working conditions. The results reveal that the flow ripples from the optimal solutions are smaller using the cross-angle and pressure relief grooves than those using the cross-angle and ordinary precompression and decompression angles and the cross-angle can be smaller. In addition, when the optimal design is used, the outlet flow ripples sensitivity can be reduced significantly.

  19. Refrigerant Control Strategies for Residential Air-Conditioning and Heat-Pump System

    Institute of Scientific and Technical Information of China (English)

    SU Shun-yu; ZHANG Chun-zhi; CHEN Jian

    2009-01-01

    This paper simulated the optimal refrigerant charge inventory of a refrigeration system in air-con-ditioning operation and heat-pump operation respectively,and studied the refrigerant control strategies in this system.The void fraction in two-phase fluid region was calculated by Harms model.And based on distributed parameter model and Harms model,the refrigerant charge inventory in condenser and evaporator were calculated and analyzed in air-conditioning conditions and heat-pump conditions,respectively.The calculating results of dif-ferent refrigerant mass between refrigeration and heating conditions indicate that the optimal refrigerant charge inventory in heat-pump conditions is lower than that in air-eonditioning conditions.To avoid the decrease of COP due to the surplus refrigerant in heating conditions,we introduced the liquid reservoir control method and associate capillary control method.Both of them could increase the heating capacity of the air-source heat pump-The difference of optimal refrigerant charge inventory in air-conditioning and heat-pump system can be controlled by the liquid reservoir or the associate capillary.

  20. NUMERICAL SIMULATION OF FLOW OF PULP FIBER SUSPENSIONS IN STOCK PUMP WITH SEMI-OPEN IMPELLER

    Institute of Scientific and Technical Information of China (English)

    Li Hong; Yuan Shouqi; Liu Weiwei

    2005-01-01

    The flow of pulp fiber suspensions with a consistency below 5% through a pump falls into the turbulent region. The 2-phase 3D turbulent flow of the mixture is simulated in the hydraulic components composed by suction chamber, front board, semi-impeller and volute casing for the first time.The pseudo-fluid model and the k-ε turbulent model are modified. Phase coupled SIMPLE algorithm is applied to make pressure-velocity correction equation. Based on the results of the numerical simulation, the distribution of velocity, pressure and density of liquid and particle phase are compared and analyzed. The flow analysis in the tip between front board and impeller is emphasized, which reflects the advantage of semi-open impeller when it transports.2-phase medium. This calculation result will be helpful for the design of pump impeller and the establishment of design method of centrifugal stock pump.

  1. NUMERICAL INVESTIGATION OF PERFORMANCE OF AN AXIAL-FLOW PUMP WITH INDUCER

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The interaction of flow through the inducer and impeller of an axial-flow pump equipped with an inducer has significant effect on its performance. This article presents a recent numerical investigation on this topic. The studied pump has an inducer with 3 blades mounted on a conical hub and a 6-blade impeller. The blade angle of the impeller is adjustable to generate different relative circumferential angles between the inducer blade trailing edge and the impeller blade leading edge. A computational fluid dynamics code was used to investigate the flow characteristics and performance of the axial-flow pump. For turbulence closure, the RNG k-ε model was applied with an unstructured grid system. The rotor-stator interaction was treated with a Multiple Reference Frame (MRF) strategy. Computations were performed in different cases: 7 different relative circumferential angles (△θ) between the inducer blade trailing edge and the impeller blade leading edge, and 3 different axial gaps (G) between the inducer and the impeller. The variation of the hydraulic loss in the rotator was obtained by changing △θ. The numerical results show that the pressure generated is minimum in the case of (G=%3D), which indicates that the interference between inducer and impeller is strong if the axial gap is small. The pump performances were predicted and compared to the experimental measurements. Recommendations for future modifications and improvements to the pump design were also given.

  2. Test investigation on hydraulic losses in the discharge passage of an axial-flow pump

    Institute of Scientific and Technical Information of China (English)

    QIU Baoyun; CAO Haihong; JIANG Wei; GAO Zhaohui; WANG Fei

    2007-01-01

    In a discharge passage with a guide blade dis- charge circulation and secondary flow because of bend pipe, the flow in a 1-channel discharge passage of an axial flow pump is a complicated spiral flow. For a 2-channel passage, the discharge in the left channel is bigger than that in the fight, and the passage hydraulic losses are abnormal. In this study, the section current energy of the passage is accurately mea- sured and determined with a 5-hole probe. The hydraulic loss characteristics are determined and analyzed. The methods deducing the hydraulic losses are investigated. The results indicate that the passage hydraulic losses are not proportional to the flow discharge. Compared with a circular pipe, the hydraulic losses of a divergent discharge passage are smaller and the pump assembly efficiency is 10%-30% higher. As for the 1-channel passage, the axial-flow pump outlet circulation is usually too big; the passage hydraulic losses are also big, but a small circulation can slightly reduce hydraulic losses. As for the 2-channel passage, discharges in the two channels are not equal and the hydraulic losses increase. The outlet guide blade with a small discharge circulation or without circulation could reduce discharge passage hydraulic losses and increase pump assembly efficiency by 6%-11%.

  3. Highly stable superhydrophobic surfaces under flow conditions

    Science.gov (United States)

    Lee, Moonchan; Yim, Changyong; Jeon, Sangmin

    2015-01-01

    We synthesized hydrophobic anodic aluminum oxide nanostructures with pore diameters of 35, 50, 65, and 80 nm directly on quartz crystal microresonators, and the stability of the resulting superhydrophobicity was investigated under flow conditions by measuring changes in the resonance frequency and dissipation factor. When the quartz substrates were immersed in water, their hydrophobic surfaces did not wet due to the presence of an air interlayer. The air interlayer was gradually replaced by water over time, which caused decreases in the resonance frequency (i.e., increases in mass) and increases in the dissipation factor (i.e., increases in viscous damping). Although the water contact angles of the nanostructures increased with increasing pore size, the stability of their superhydrophobicity increased with decreasing pore size under both static conditions (without flow) and dynamic conditions (with flow); this increase can be attributed to an increase in the solid surface area that interacts with the air layer above the nanopores as the pore size decreases. Further, the effects of increasing the flow rate on the stability of the superhydrophobicity were quantitatively determined.

  4. 3D CFD modeling of flowing-gas DPALs with different pumping geometries and various flow velocities

    Science.gov (United States)

    Yacoby, Eyal; Waichman, Karol; Sadot, Oren; Barmashenko, Boris D.; Rosenwaks, Salman

    2017-01-01

    Scaling-up flowing-gas diode pumped alkali lasers (DPALs) to megawatt class power is studied using accurate three-dimensional computational fluid dynamics model, taking into account the effects of temperature rise and losses of alkali atoms due to ionization. Both the maximum achievable power and laser beam quality are estimated for Cs and K lasers. We examined the influence of the flow velocity and Mach number M on the maximum achievable power of subsonic and supersonic lasers. For Cs DPAL devices with M = 0.2 - 3 the output power increases with increasing M by only 20%, implying that supersonic operation mode has only small advantage over subsonic. In contrast, the power achievable in K DPALs strongly depends on M. The output power increases by 100% when M increases from 0.2 to 4, showing a considerable advantage of supersonic device over subsonic. The reason for the increase of the power with M in both Cs and K DPALs is the decrease of the temperature due to the gas expansion in the flow system. However, the power increase for K lasers is much larger than for the Cs devices mainly due to the much smaller fine-structure splitting of the 2P states ( 58 cm-1 for K and 554 cm-1 for Cs), which results in a much stronger effect of the temperature decrease in K DPALs. For pumping by beams of the same rectangular cross section, comparison between end-pumping and transverse-pumping shows that the output power is not affected by the pump geometry. However, the intensity of the output laser beam in the case of transverse-pumped DPALs is strongly non-uniform in the laser beam cross section resulting in higher brightness and better beam quality in the far field for the end-pumping geometry where the intensity of the output beam is uniform.

  5. Theoretical investigation on exciplex pumped alkali vapor lasers with sonic-level gas flow

    Science.gov (United States)

    Xu, Xingqi; Shen, Binglin; Huang, Jinghua; Xia, Chunsheng; Pan, Bailiang

    2017-07-01

    Considering the effects of higher excited and ion energy states and utilizing the methodology in the fluid mechanics, a modified model of exciplex pumped alkali vapor lasers with sonic-level flowing gas is established. A comparison of output characters between subsonic flow and supersonic flow is made. In this model, higher excited and ion energy states are included as well, which modifies the analysis of the kinetic process and introduces larger heat loading in an operating CW exciplex-pumped alkali vapor laser. The results of our calculations predict that subsonic flow has an advantage over supersonic flow under the same fluid parameters, and stimulated emission in the supersonic flow would be quenched while the pump power reaching a threshold value of the fluid choking effect. However, by eliminating the influence of fluid characters, better thermal management and higher optical conversion efficiency can be obtained in supersonic flow. In addition, we make use of the "nozzle-diffuser" to build up the closed-circle flowing experimental device and gather some useful simulated results.

  6. Hydraulic testing of intravascular axial flow blood pump designs with a protective cage of filaments for mechanical cavopulmonary assist.

    Science.gov (United States)

    Kapadia, Jugal Y; Pierce, Kathryn C; Poupore, Amy K; Throckmorton, Amy L

    2010-01-01

    To provide hemodynamic support to patients with a failing single ventricle, we are developing a percutaneously inserted, magnetically levitated axial flow blood pump designed to augment pressure in the cavopulmonary circulation. The device is designed to serve as a bridge-to-transplant, bridge-to-recovery, bridge-to-hemodynamic stability, or bridge-to-surgical reconstruction. This study evaluated the hydraulic performance of three blood pump prototypes (a four-bladed impeller, a three-bladed impeller, and a three-bladed impeller with a four-bladed diffuser) whose designs evolved from previous design optimization phases. Each prototype included the same geometric protective cage of filaments, which stabilize the rotor within the housing and protect the housing wall from the rotating blades. All prototypes delivered pressure rises over a range of flow rates and rotational speeds that would be sufficient to augment hemodynamic conditions in the cavopulmonary circulation. The four-bladed impeller outperformed the two remaining prototypes by >40%; this design was able to generate a pressure rise of 4-28 mm Hg for flow rates of 0.5-10 L/min at rotational speeds of 4,000-7,000 RPM. Successful development of this blood pump will provide clinicians with a feasible therapeutic option for mechanically supporting the failing Fontan.

  7. Simulation model of a variable-speed pumped-storage power plant in unstable operating conditions in pumping mode

    Science.gov (United States)

    Martínez-Lucas, G.; Pérez-Díaz, J. I.; Sarasúa, J. I.; Cavazzini, G.; Pavesi, G.; Ardizzon, G.

    2017-04-01

    This paper presents a dynamic simulation model of a laboratory-scale pumped-storage power plant (PSPP) operating in pumping mode with variable speed. The model considers the dynamic behavior of the conduits by means of an elastic water column approach, and synthetically generates both pressure and torque pulsations that reproduce the operation of the hydraulic machine in its instability region. The pressure and torque pulsations are generated each from a different set of sinusoidal functions. These functions were calibrated from the results of a CFD model, which was in turn validated from experimental data. Simulation model results match the numerical results of the CFD model with reasonable accuracy. The pump-turbine model (the functions used to generate pressure and torque pulsations inclusive) was up-scaled by hydraulic similarity according to the design parameters of a real PSPP and included in a dynamic simulation model of the said PSPP. Preliminary conclusions on the impact of unstable operation conditions on the penstock fatigue were obtained by means of a Monte Carlo simulation-based fatigue analysis.

  8. Effect of intra-aortic balloon pump on coronary blood flow during different balloon cycles support: A computer study.

    Science.gov (United States)

    Aye, Thin Pa Pa; Htet, Zwe Lin; Singhavilai, Thamvarit; Naiyanetr, Phornphop

    2015-01-01

    Intra-aortic balloon pump (IABP) has been used in clinical treatment as a mechanical circulatory support device for patients with heart failure. A computer model is used to study the effect on coronary blood flow (CBF) with different balloon cycles under both normal and pathological conditions. The model of cardiovascular and IABP is developed by using MATLAB SIMULINK. The effect on coronary blood flow has been studied under both normal and pathological conditions using different balloon cycles (balloon off; 1:4; 1:2; 1:1). A pathological heart is implemented by reducing the left ventricular contractility. The result of this study shows that the rate of balloon cycles is related to the level of coronary blood flow.

  9. Investigation on magnesium degradation under flow versus static conditions using a novel impedance-driven flow apparatus

    Institute of Scientific and Technical Information of China (English)

    Elbert David Mai; Huinan Liu

    2014-01-01

    This article reports a novel impedance-driven flow apparatus and its applicability for studying magnesium degradation under flow versus static conditions. Magnesium has potential to be an effective biomaterial for use inside the human body due to its biodegradability and biocompatibility. Magnesium undergoes degradation reactions in aqueous solutions such as body fluids, leading to mass loss and pH increase of the surrounding fluid. To compare the degradation process of magnesium under flow versus static conditions, a novel flow apparatus consisting of an impedance pump and a flow chamber was designed and constructed. In addition to low-cost, this apparatus is flexible to be sterilized and assembled, and is small enough for use inside an incubator, making it appealing for measuring and comparing magnesium degradation in vitro under flow versus static conditions. The average flow rate in this flow apparatus was 2.8 ml/s, mimicking the flow rate (2.6 ml/s) in coronary artery. In a simulated body fluid (SBF), magnesium samples lost their mass at a much faster rate under the flow condition than that under the static condition. Starting with a pH of 7.4, the SBF showed a pH increase to 8.5 under the flow condition within 96 h due to the degradation of magnesium, greater than the pH increase under the static condition. The results of this study demonstrated the effects of fluid flow on magnesium degradation using the impedance-driven flow apparatus, providing useful design guidelines for magnesium-based implants that may be exposed to body fluid flow.

  10. Air Ejector Pumping Enhancement Through Pulsing Primary Flow

    Science.gov (United States)

    2005-12-01

    CFD ) analysis show that pulsing the primary jet flow, an active metho of flow control, improved ejector performance. The physics of this improvement...without an entrance shape was found to be still reasonably efficient. Both experiments and Computer Fluid Dynamics( CFD ) analysis show that pulsing the...other shapes. A tube without an entrance shape was found to be still reasonably efficient. Both experiments and Computer Fluid Dynamics( CFD ) analysis

  11. Stationary flow conditions in pulsed supersonic beams.

    Science.gov (United States)

    Christen, Wolfgang

    2013-10-21

    We describe a generally applicable method for the experimental determination of stationary flow conditions in pulsed supersonic beams, utilizing time-resolved electron induced fluorescence measurements of high pressure jet expansions of helium. The detection of ultraviolet photons from electronically excited helium emitted very close to the nozzle exit images the valve opening behavior-with the decided advantage that a photon signal is not affected by beam-skimmer and beam-residual gas interactions; it thus allows to conclusively determine those operation parameters of a pulsed valve that yield complete opening. The studies reveal that a "flat-top" signal, indicating constant density and commonly considered as experimental criterion for continuous flow, is insufficient. Moreover, translational temperature and mean terminal flow velocity turn out to be significantly more sensitive in testing for the equivalent behavior of a continuous nozzle source. Based on the widely distributed Even-Lavie valve we demonstrate that, in principle, it is possible to achieve quasi-continuous flow conditions even with fast-acting valves; however, the two prerequisites are a minimum pulse duration that is much longer than standard practice and previous estimates, and a suitable tagging of the appropriate beam segment.

  12. A new method of providing pulsatile flow in a centrifugal pump: assessment of pulsatility using a mock circulatory system.

    Science.gov (United States)

    Herreros, Jesús; Berjano, Enrique J; Sales-Nebot, Laura; Más, Pedro; Calvo, Irene; Mastrobuoni, Stefano; Mercé, Salvador

    2008-06-01

    Previous studies have demonstrated the potential advantages of pulsatile flow as compared with continuous flow. However, to date, physiologic pumps have been technically complex and their application has therefore remained in the experimental field. We have developed a new type of centrifugal pump, which can provide pulsatile as well as continuous flow. The inner wall of a centrifugal pump is pulsed by means of a flexible membrane, which can be accurately controlled by means of either a hydraulic or pneumatic driver. The aim of this study was to assess the hydraulic behavior of the new pump in terms of surplus hemodynamic energy (SHE). We conducted experiments using a mock circulatory system including a membrane oxygenator. No differences were found in the pressure-flow characteristics between the new pump and a conventional centrifugal pump, suggesting that the inclusion of the flexible membrane does not alter hydraulic performance. The value of SHE rose when systolic volume was increased. However, SHE dropped when the percentage of ejection time was reduced and also when the continuous flow (programmed by the centrifugal console) increased. Mean flow matched well with the continuous flow set by the centrifugal console, that is, the pulsatile component of the flow was exclusively controlled by the pulsatile console, and was therefore independent of the continuous flow programmed by the centrifugal console. The pulsatility of the new pump was approximately 25% of that created with a truly pulsatile pump.

  13. Effect of reference conditions on flow rate, modifier fraction and retention in supercritical fluid chromatography.

    Science.gov (United States)

    De Pauw, Ruben; Shoykhet Choikhet, Konstantin; Desmet, Gert; Broeckhoven, Ken

    2016-08-12

    When using compressible mobile phases such as fluidic CO2, the density, the volumetric flow rates and volumetric fractions are pressure dependent. The pressure and temperature definition of these volumetric parameters (referred to as the reference conditions) may alter between systems, manufacturers and operating conditions. A supercritical fluid chromatography system was modified to operate in two modes with different definition of the eluent delivery parameters, referred to as fixed and variable mode. For the variable mode, the volumetric parameters are defined with reference to the pump operating pressure and actual pump head temperature. These conditions may vary when, e.g. changing the column length, permeability, flow rate, etc. and are thus variable reference conditions. For the fixed mode, the reference conditions were set at 150bar and 30°C, resulting in a mass flow rate and mass fraction of modifier definition which is independent of the operation conditions. For the variable mode, the mass flow rate of carbon dioxide increases with system pump operating pressure, decreasing the fraction of modifier. Comparing the void times and retention factor shows that the deviation between the two modes is almost independent of modifier percentage, but depends on the operating pressure. Recalculating the set volumetric fraction of modifier to the mass fraction results in the same retention behaviour for both modes. This shows that retention in SFC can be best modelled using the mass fraction of modifier. The fixed mode also simplifies method scaling as it only requires matching average column pressure.

  14. A Laminar Flow-Based Microfluidic Tesla Pump via Lithography Enabled 3D Printing.

    Science.gov (United States)

    Habhab, Mohammed-Baker; Ismail, Tania; Lo, Joe Fujiou

    2016-11-23

    Tesla turbine and its applications in power generation and fluid flow were demonstrated by Nicholas Tesla in 1913. However, its real-world implementations were limited by the difficulty to maintain laminar flow between rotor disks, transient efficiencies during rotor acceleration, and the lack of other applications that fully utilize the continuous flow outputs. All of the aforementioned limits of Tesla turbines can be addressed by scaling to the microfluidic flow regime. Demonstrated here is a microscale Tesla pump designed and fabricated using a Digital Light Processing (DLP) based 3D printer with 43 µm lateral and 30 µm thickness resolutions. The miniaturized pump is characterized by low Reynolds number of 1000 and a flow rate of up to 12.6 mL/min at 1200 rpm, unloaded. It is capable of driving a mixer network to generate microfluidic gradient. The continuous, laminar flow from Tesla turbines is well-suited to the needs of flow-sensitive microfluidics, where the integrated pump will enable numerous compact lab-on-a-chip applications.

  15. A Laminar Flow-Based Microfluidic Tesla Pump via Lithography Enabled 3D Printing

    Directory of Open Access Journals (Sweden)

    Mohammed-Baker Habhab

    2016-11-01

    Full Text Available Tesla turbine and its applications in power generation and fluid flow were demonstrated by Nicholas Tesla in 1913. However, its real-world implementations were limited by the difficulty to maintain laminar flow between rotor disks, transient efficiencies during rotor acceleration, and the lack of other applications that fully utilize the continuous flow outputs. All of the aforementioned limits of Tesla turbines can be addressed by scaling to the microfluidic flow regime. Demonstrated here is a microscale Tesla pump designed and fabricated using a Digital Light Processing (DLP based 3D printer with 43 µm lateral and 30 µm thickness resolutions. The miniaturized pump is characterized by low Reynolds number of 1000 and a flow rate of up to 12.6 mL/min at 1200 rpm, unloaded. It is capable of driving a mixer network to generate microfluidic gradient. The continuous, laminar flow from Tesla turbines is well-suited to the needs of flow-sensitive microfluidics, where the integrated pump will enable numerous compact lab-on-a-chip applications.

  16. A Laminar Flow-Based Microfluidic Tesla Pump via Lithography Enabled 3D Printing

    Science.gov (United States)

    Habhab, Mohammed-Baker; Ismail, Tania; Lo, Joe Fujiou

    2016-01-01

    Tesla turbine and its applications in power generation and fluid flow were demonstrated by Nicholas Tesla in 1913. However, its real-world implementations were limited by the difficulty to maintain laminar flow between rotor disks, transient efficiencies during rotor acceleration, and the lack of other applications that fully utilize the continuous flow outputs. All of the aforementioned limits of Tesla turbines can be addressed by scaling to the microfluidic flow regime. Demonstrated here is a microscale Tesla pump designed and fabricated using a Digital Light Processing (DLP) based 3D printer with 43 µm lateral and 30 µm thickness resolutions. The miniaturized pump is characterized by low Reynolds number of 1000 and a flow rate of up to 12.6 mL/min at 1200 rpm, unloaded. It is capable of driving a mixer network to generate microfluidic gradient. The continuous, laminar flow from Tesla turbines is well-suited to the needs of flow-sensitive microfluidics, where the integrated pump will enable numerous compact lab-on-a-chip applications. PMID:27886051

  17. Water Flow Performance of a Superscale Model of the Fastrac Liquid Oxygen Pump

    Science.gov (United States)

    Skelley, Stephen; Zoladz, Thomas

    2001-01-01

    As part of the National Aeronautics and Space Administration's ongoing effort to lower the cost of access to space, the Marshall Space Flight Center has developed a rocket engine with 60,000 pounds of thrust for use on the Reusable Launch Vehicle technology demonstrator slated for launch in 2000. This gas generator cycle engine, known as the Fastrac engine, uses liquid oxygen and RP-1 for propellants and includes single stage liquid oxygen and RP-1 pumps and a single stage supersonic turbine on a common shaft. The turbopump design effort included the first use and application of new suction capability prediction codes and three-dimensional blade generation codes in an attempt to reduce the turbomachinery design and certification costs typically associated with rocket engine development. To verify the pump's predicted cavitation performance, a water flow test of a superscale model of the Fastrac liquid oxygen pump was conducted to experimentally evaluate the liquid oxygen pump's performance at and around the design point. The water flow test article replicated the flow path of the Fastrac liquid oxygen pump in a 1.582x scale model, including scaled seal clearances for correct leakage flow at a model operating speed of 5000 revolutions per minute. Flow entered the 3-blade axial-flow inducer, transitioned to a shrouded, 6- blade radial impeller, and discharged into a vaneless radial diffuser and collection volute. The test article included approximately 50 total and static pressure measurement locations as well as flush-mounted, high frequency pressure transducers for complete mapping of the pressure environment. The primary objectives of the water flow test were to measure the steady-state and dynamic pressure environment of the liquid oxygen pump versus flow coefficient, suction specific speed, and back face leakage flow rate. Initial results showed acceptable correlation between the predicted and experimentally measured pump head rise at low suction specific speeds

  18. THE FIRST DOMESTIC IMPLANTABLE AXIAL FLOW PUMP: RESULTS OF EXPERIMENTAL STUDIES IN CALVES

    Directory of Open Access Journals (Sweden)

    G. P. Itkin

    2013-01-01

    Full Text Available Aim of our experimental study was evaluation of the first domestic implantable axial pump as a left ventricle assist device in calves. Materials and methods. 18 calves 90–120 days of age, weighing 95 ± 5 kg were exposed to implantation of an axial pump under the scheme «left ventricular – aorta» in paracorporeal and implantable in chest cavity versions. Two models of the pump were tested. Model 1 is a pump with cylindrical bearings and elongated straightener, model 2 had ball bearings and modified design of impeller and straightener. Results. In the first series (n = 12 the pump model 1 was tested. The duration of experiments was 4,9 ± 5,3 days, maximal duration was 16 days. The experiments were finalized due to intraoperation cardiac fibrillation (n = 3, uncrop- ped acute bleeding (n = 3, lowering of blood flow through the pump of 60 ± 15% (n = 6 because of thrombo- sis of the pump (n = 5 and outlet line (n = 1, in 3 cases of 5, combined with mechanical wear of bearings. In the second series (n = 6 the pump model 2 was tested. In 4 experiments of 6 the duration was 74,5 ± 29 days. One experiment was finalized due to intraoperation cardiac fibrillation. Another one experiment was finalized on 8 day as planned. In 5 experiments there was absence of either thrombosis or mechanical wear of bearings. Morphological and histological examination of the kidneys, liver and lungs in the 5 experiments of second series did not reveal the presence of zones of ischemia or thromboembolia. Conclusion. The results of the second series can be treaded as preclinical testing of the first domestic implantable axial pump as a left ventricle assist device in calves. 

  19. Gas flow through the clearances of screw spindle vacuum pumps; Gasspaltstroemungen in Schraubenspindel-Vakuumpumpen

    Energy Technology Data Exchange (ETDEWEB)

    Kauder, K.; Wenderott, D. [Dortmund Univ. (Germany). FG Fluidenergiemaschinen

    1998-12-31

    The documentation `Schraubenmaschinen` deals with the subject `screw spindle vacuum pump` for the first time. Therefore, this paper presents the type of maschine `screw spindle vacuum pump`, fixes its limits to the better known screw type compressor and finally classifies it in the crossover of vacuum-technology, characteristic geometry and the numerical simulation. The suggested reflections to choose a proper model of flow are based on the geometry of the screw spindle vacuum pump and fundamentals concerning the vacuum-technology and the state of flow. (orig.) [Deutsch] Die Schriftenreihe `Schraubenmaschinen` behandelt erstmals das Thema `Schraubenspindel-Vakuumpumpe`. Aus diesem Grund stellt der vorliegende Beitrag den Maschinentyp Schraubenspindel-Vakuumpumpe vor, grenzt ihn zur bekannteren Schraubenmaschine ab und ordnet ihn in der Schnittmenge aus Vakuumtechnik, charakteristischer Maschinengeometrie und der Simulation ein. Auf den vakuumtechnischen und stroemungstechnischen Grundlagen sowie geometrischen Betrachtungen basieren die genannten Ueberlegungen zur Auswahl geeigneter Stroemungsmodelle. (orig.)

  20. Clinical evaluation of pulsatile flow mode of Terumo Capiox centrifugal pump.

    Science.gov (United States)

    Nishida, H; Uesugi, H; Nishinaka, T; Uwabe, K; Aomi, S; Endo, M; Koyanagi, H; Oshiyama, H; Nogawa, A; Akutsu, T

    1997-07-01

    The Terumo Capiox centrifugal pump system possesses an automatic priming function in which the motor repeatedly stops and runs intermittently to eliminate air bubbles in the circuit through the micropores of the hollow-fiber membrane oxygenator. By modifying this mechanism, we have developed a pulsatile flow mode. In this mode, maximum and minimum pump rotational speeds can be independently set every 20 rpm in the range of 0 to 3,000 rpm. The duration of the pump run at maximum and minimum speeds can also be independently set every 0.1 s in the range of 0.2 to 15 s. In a clinical trial, after obtaining the desired flow rate, 2.4 L/min/m2 in nonpulsatile flow mode, a pulsatile flow mode of 60 cycles/min (with 1 cycle being maximum speed for 0.4 s and minimum speed for 0.6 s) was obtained by adding and subtracting 500 rpm to and from the rotational speed in nonpulsatile flow mode. Pulse pressures in the femoral artery and in the circuit just proximal to the perfusion cannula (6.5 mm Sarns high flow cannula with metal tip) were measured in 5 patients who underwent pulsatile cardiopulmonary bypass (CPB) for a coronary artery bypass graft (CABG), and compared to pulse pressures obtained by intraaortic balloon pumping (IABP) in 3 patients and by the pulsatile mode of the 3M Delphin pump in 3 patients. The platelet count, free hemoglobin, and beta-thromboglobulin (beta-TG) were measured and compared with measurements from another 5 patients who underwent nonpulsatile CPB. Although the pulse pressure measured in the circuit was 180 mm Hg on average, the pressure in the femoral artery was only 15 to 40 mm Hg with a mean of 20 mm Hg. In the same patients, 60 to 80 mm Hg pulse pressure was obtained with IABP. The pulse pressure obtained with the Delphin pump was not more than that obtained with the Terumo pump. There were no significant differences in percents of preoperative levels of platelet counts (pulsatile, 87.6 +/- 15.8% and nonpulsatile, 72.4 +/- 40.6%), free

  1. Investigation into Transient Flow in a Centrifugal Pump with Wear Ring Clearance Variation

    Directory of Open Access Journals (Sweden)

    Houlin Liu

    2014-04-01

    Full Text Available The leakage flow paths in the sidewall gaps of centrifugal pumps are of significant importance for numbers of effects. The paper is concerned with the transient flow in the leakage flow paths with wear ring clearance variation. For this purpose, numerical simulations of the whole pump were carried out. The grid dependence and yplus check were performed first. Additionally, experimental data of performance characteristic and pressure fluctuation inside the sidewall gap was used to validate the numerical results. The transient velocity fields inside the sidewall gaps during one blade passage period were simulated. And the leakage through the wear ring gap was obtained for all operating points investigated. To have a better idea of attenuation and propagation of pressure inside the sidewall gap, the unsteady pressure distributions in the gap were calculated. Additionally, the surfaces of the impeller were divided into four parts. The fluid force on each part was expressed as a percentage of the total radial force. Through comparing the flow fields, the pressure distributions, and the radial force between the pumps with different wear ring clearances, the effects of the wear ring clearance were discussed in detail. The results can be used to guide the optimum design of the pump sidewall gaps.

  2. A hydrodynamically suspended, magnetically sealed mechanically noncontact axial flow blood pump: design of a hydrodynamic bearing.

    Science.gov (United States)

    Mitamura, Yoshinori; Kido, Kazuyuki; Yano, Tetsuya; Sakota, Daisuke; Yambe, Tomoyuki; Sekine, Kazumitsu; OKamoto, Eiji

    2007-03-01

    To overcome the drive shaft seal and bearing problem in rotary blood pumps, a hydrodynamic bearing, a magnetic fluid seal, and a brushless direct current (DC) motor were employed in an axial flow pump. This enabled contact-free rotation of the impeller without material wear. The axial flow pump consisted of a brushless DC motor, an impeller, and a guide vane. The motor rotor was directly connected to the impeller by a motor shaft. A hydrodynamic bearing was installed on the motor shaft. The motor and the hydrodynamic bearing were housed in a cylindrical casing and were waterproofed by a magnetic fluid seal, a mechanically noncontact seal. Impeller shaft displacement was measured using a laser sensor. Axial and radial displacements of the shaft were only a few micrometers for motor speed up to 8500 rpm. The shaft did not make contact with the bearing housing. A flow of 5 L/min was obtained at 8000 rpm at a pressure difference of 100 mm Hg. In conclusion, the axial flow blood pump consisting of a hydrodynamic bearing, a magnetic fluid seal, and a brushless DC motor provided contact-free rotation of the impeller without material wear.

  3. Modeling and experiments on differential pumping in linear plasma generators operating at high gas flows

    NARCIS (Netherlands)

    van Eck, H. J. N.; Koppers, W. R.; van Rooij, G. J.; W. J. Goedheer,; Engeln, R.; D.C. Schram,; Cardozo, N. J. L.; Kleyn, A. W.

    2009-01-01

    The direct simulation Monte Carlo (DSMC) method was used to investigate the efficiency of differential pumping in linear plasma generators operating at high gas flows. Skimmers are used to separate the neutrals from the plasma beam, which is guided from the source to the target by a strong axial mag

  4. PIV measurements and CFD computations of secondary flow in a centrifugal pump impeller

    NARCIS (Netherlands)

    Westra, R.W.; Broersma, L.; Andel, van K.; Kruyt, N.P.

    2010-01-01

    Two-dimensional particle image velocimetry measurements and three-dimensional computational fluid dynamics (CFD) analyses have been performed on the steady velocity field inside the shrouded impeller of a low specific-speed centrifugal pump operating with a vaneless diffuser. Flow rates ranging from

  5. Numerical simulation of transient flow performance during different periods in centrifugal pump

    Institute of Scientific and Technical Information of China (English)

    HUANG Si; ZHANG Jie; ZHANG Xuejiao; SU Xianghui

    2016-01-01

    The instantaneous variations of the hydraulic characteristics take place in centrifugal pumps during their start-up,shutdown and other variable speed operations.In this paper,the variable speed method was proposed to simulate the transient internal flow field and the external performance of the pump during starting and stopping periods.The terms of accelerations due to variable speeds in the flow governing equations were analyzed in a multiple reference of frame (MRF).A transient CFD simulation was performed for a typical centrifugal pump by using ANSYS-CFX with the standard k-εturbulence model.The entire simulation process was composed of four stages:start-up,normal run,shutdown and post-shutdown.The function of rotating speed with regard to time was set by CEL language directly into the impeller domain in the pre-processor of the software to conduct variable speed simulation.The varia-tions of the flow field in the centrifugal pump were obtained from the transient simulation.The changing laws of flow rate,head and other performance parameters over time were also analyzed and summarized.

  6. Computational fluid dynamics analysis of a mixed flow pump impeller

    African Journals Online (AJOL)

    ATHARVA

    results of CFD analysis, the velocity and pressure in the outlet of the impeller is predicted. ... The numerical simulation can provide quite accurate information on the fluid ... of the computational domain the mass flow rate, the turbulence intensity, and a reference pressure are specified. .... Averaged velocity distribution.

  7. 3D CFD modeling of subsonic and transonic flowing-gas DPALs with different pumping geometries

    Science.gov (United States)

    Yacoby, Eyal; Sadot, Oren; Barmashenko, Boris D.; Rosenwaks, Salman

    2015-10-01

    Three-dimensional computational fluid dynamics (3D CFD) modeling of subsonic (Mach number M ~ 0.2) and transonic (M ~ 0.9) diode pumped alkali lasers (DPALs), taking into account fluid dynamics and kinetic processes in the lasing medium is reported. The performance of these lasers is compared with that of supersonic (M ~ 2.7 for Cs and M ~ 2.4 for K) DPALs. The motivation for this study stems from the fact that subsonic and transonic DPALs require much simpler hardware than supersonic ones where supersonic nozzle, diffuser and high power mechanical pump (due to a drop in the gas total pressure in the nozzle) are required for continuous closed cycle operation. For Cs DPALs with 5 x 5 cm2 flow cross section pumped by large cross section (5 x 2 cm2) beam the maximum achievable power of supersonic devices is higher than that of the transonic and subsonic devices by only ~ 3% and ~ 10%, respectively. Thus in this case the supersonic operation mode has no substantial advantage over the transonic one. The main processes limiting the power of Cs supersonic DPALs are saturation of the D2 transition and large ~ 60% losses of alkali atoms due to ionization, whereas the influence of gas heating is negligible. For K transonic DPALs both the gas heating and ionization effects are shown to be unimportant. The maximum values of the power are higher than those in Cs transonic laser by ~ 11%. The power achieved in the supersonic and transonic K DPAL is higher than for the subsonic version, with the same resonator and K density at the inlet, by ~ 84% and ~ 27%, respectively, showing a considerable advantaged of the supersonic device over the transonic one. For pumping by rectangular beams of the same (5 x 2 cm2) cross section, comparison between end-pumping - where the laser beam and pump beam both propagate at along the same axis, and transverse-pumping - where they propagate perpendicularly to each other, shows that the output power and optical-to-optical efficiency are not

  8. An HTS flux pump operated by directly driving a superconductor into flux flow region in the E- J curve

    Science.gov (United States)

    Geng, Jianzhao; Coombs, T. A.

    2016-09-01

    High-T c superconducting (HTS) flux pumps are capable of compensating the persistent current decay in HTS magnets without electrical contact. In this paper, following work on a low-T c superconducting self-switching flux pump, we propose a new HTS flux pump by directly driving a high-T c superconductor into the flux flow region in the E- J curve. The flux pump consists of a transformer which has a superconducting secondary winding shorted by an YBCO-coated conductor bridge. A high alternating current with a much higher positive peak value than the negative peak value is induced in the secondary winding. The current always drives the bridge superconductor into the flux flow region only at around its positive peak value, thus resulting in flux pumping. The proposed flux pump is much simpler than existing HTS flux pumps.

  9. Variation analysis of flow rate delivered using a blister pump

    Science.gov (United States)

    Selvakumar, Sivesh; Linares, Rodrigo; Oppenheimer, Aaron; Anthony, Brian

    2012-03-01

    Components for on-chip storage and delivery of liquid reagent are necessary for many commercial applications of lab-on- a-chip technology. One such system uses a 'blister-pack' that is pushed by an actuator. This paper explores the sensitivity of the flow rate produced by a blister-actuator pair to the expected manufacturing variations in its dimensions. A numerical model of the blister-actuator pair is developed and the tool of Variation Simulation Modeling (VSM) is used to determine the robustness of fluid delivery. For a flow-rate requirement of +/- 10%, the number of out-of-spec parts is found to be less than 0.01%. The critical dimensions that need to be controlled to improve robustness are also identified.

  10. Flow Instabilities in Cavitating and Non-Cavitating Pumps

    Science.gov (United States)

    2006-11-01

    stall and surge may occur in non-cavitating turbomachines at flow rates smaller than design. Rotating stall is a local instability at the...turbomachinery which is basically not dependent on the hydraulic system in which the turbomachine is installed. The stalled region rotates faster than impeller...rate and without significant head decrease. So, it is required to confirm the absence of cavitation instabilities, whenever the turbomachine is

  11. Quantification of the secondary flow in a radial coupled centrifugal blood pump based on particle tracking velocimetry.

    Science.gov (United States)

    Watanabe, Nobuo; Masuda, Takaya; Iida, Tomoya; Kataoka, Hiroyuki; Fujimoto, Tetsuo; Takatani, Setsuo

    2005-01-01

    Secondary flow in the centrifugal blood pump helps to enhance the washout effect and to minimize thrombus formation. On the other hand, it has an adverse effect on pump efficiency. Excessive secondary flow may induce hemolytic effects. Understanding the secondary flow is thus important to the design of a compact, efficient, biocompatible blood pump. This study examined the secondary flow in a radial coupled centrifugal blood pump based on a simple particle tracking velocimetry (PTV) technique. A radial magnetically coupled centrifugal blood pump has a bell-shaped narrow clearance between the impeller inner radius and the pump casing. In order to vary the flow levels through the clearance area, clearance widths of 0.25 mm and 0.50 mm and impeller washout holes with diameters of 0 mm, 2.5 mm, and 4 mm were prepared. A high-speed video camera (2000 frames per second) was used to capture the particle images from which radial flow components were derived. The flow in the space behind the impeller was assumed to be laminar and Couette type. The larger the inner clearance or diameter of washout hole, the greater was the secondary flow rate. Without washout holes, the flow behind the impeller resulted in convection. The radial flow through the washout holes of the impeller was conserved in the radial as well as in the axial direction behind the impeller. The increase in the secondary flow reduced the net pump efficiency. Simple PTV was successful in quantifying the flow in the space behind the impeller. The results verified the hypothesis that the flow behind the impeller was theoretically Couette along the circumferential direction. The convection flow observed behind the impeller agreed with the reports of other researchers. Simple PTV was effective in understanding the fluid dynamics to help improve the compact, efficient, and biocompatible centrifugal blood pump for safe clinical applications.

  12. An improved turbulence model for separation flow in a centrifugal pump

    Directory of Open Access Journals (Sweden)

    Yun Ren

    2016-06-01

    Full Text Available For the stable and reliable operation of centrifugal pump, the transient flow must be studied and the separation region should be avoided. Three-dimensional, incompressible, steady, and transient flows in a centrifugal pump at specific speed within 74 were numerically studied using shear stress transport k-ω turbulence model, and an improved explicit algebraic Reynolds stress model–rotation-curvature turbulence model was proposed by considering the effects of rotation and curvature in the impeller passages in this work. Steady and transient computations were conducted to compare with the experiments. The comparison of pump hydraulic performance showed that the explicit algebraic Reynolds stress model–rotation-curvature turbulence model was better than the original model, especially between 0.6QBEP and 1.2QBEP; the improved model could enhance the head prediction of pump by about 1%–7% than that with the original model. Then, the visualization of the vortex evolution was observed to validate the unsteady simulations. Good agreement was investigated between calculations and visualizations. It is indicated that the explicit algebraic Reynolds stress model–rotation-curvature model can successfully capture the separation flow.

  13. PRINCIPLES OF DEVELOPMENT MATHEMATICAL MODEL FOR RESEARCHING OF NONPULSATILE FLOW PUMP AND CARDIAC SYSTEM

    Directory of Open Access Journals (Sweden)

    I. V. Bykov

    2013-01-01

    Full Text Available Aim. The presented research uncovers the using of mathematical modeling methods for cardio-vascular system and axial blood pump interaction analysis under heart failure with combined valve pathology. The research will pro- vide data for automated pump control algorithm synthesis. Materials and methods. Mathematical model is build up by using experiments results from mock cardio-vascular circulation loop and mathematical representation of Newtonian fluid dynamics in pulsing circulation loop. The model implemented in modeling environment Simulink (Matlab. Results. Authors implemented mathematical model which describe cardio-vascular system and left-ven- tricular assistive device interaction for intact conditions. Values of parameters for intact conditions were acquired in the experiments on animals with implanted axial pump, experiments were conducted in FRCTAO. The model was verified by comparison of instantaneous blood flowrate values in experiments and in model. Conclusion. The paper present implemented mathematical model of cardio-vascular system and axial pump interaction for intact conditions, where the pump connected between left ventricle and aorta. In the next part of research authors will use the presented model to evaluate using the biotechnical system in conditions of heart failure and valve pathology. 

  14. Experimental research on pressure fluctuation and vibration in a mixed flow pump

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Kai; Liu, Houlin; Wang, Wenbo [National Research Center of Pumps and Pumping System Engineering and Technology, Jiangsu University, Zhenjiang (China); Zhou, Xiaohua [Gree Electric Appliance Inc. of Zhuhai, Zhuhai (China)

    2016-01-15

    To study the pressure fluctuation and vibration in mixed flow pumps, we chose a mixed flow pump with specific speed of 436.1 to measure. The time domains and frequency domain at each monitoring point on diffuser and outlet elbow were analyzed, as well as the vibration frequency domain characteristics at the impeller outlet and near the motor. The results show that the peak value of pressure fluctuation peak decreased gradually with the increase of flow rate. The pressure fluctuation of each monitoring point had periodicity, and the frequency domain dominated by blade passing frequency and multiple shaft frequency. The vibration frequency of each monitoring point occurred at shaft frequency and its multiple shaft frequency. The dominant frequency and the second frequency were distributed in shaft frequency and double shaft frequency.

  15. Modeling of an Air Conditioning System with Geothermal Heat Pump for a Residential Building

    Directory of Open Access Journals (Sweden)

    Silvia Cocchi

    2013-01-01

    Full Text Available The need to address climate change caused by greenhouse gas emissions attaches great importance to research aimed at using renewable energy. Geothermal energy is an interesting alternative concerning the production of energy for air conditioning of buildings (heating and cooling, through the use of geothermal heat pumps. In this work a model has been developed in order to simulate an air conditioning system with geothermal heat pump. A ground source heat pump (GSHP uses the shallow ground as a source of heat, thus taking advantage of its seasonally moderate temperatures. GSHP must be coupled with geothermal exchangers. The model leads to design optimization of geothermal heat exchangers and to verify the operation of the geothermal plant.

  16. Flow Characteristics at the Pump-Turbine Interface of a Torque Converter at Extreme Speed Ratios

    Directory of Open Access Journals (Sweden)

    A. Habsieger

    2003-01-01

    Full Text Available The average velocity field at the pump–turbine interface in a scaled version of a truck torque converter was studied. Seven different turbine-to-pump rotational-speed ratios were examined, ranging from near stall (0.065 to overspeed (1.050 so as to determine the effect of the speed ratio on the flow field and on the mass flow rate. Laser velocimetry was used to measure the flow velocity through the pump's exit and the turbine's inlet plane. At the pump's exit, as the speed ratio increases, the high velocities move to the pressure-shell corner and then to both the core-suction and the pressureshell corners. Concentrated velocity gradients are largest at the lowest speed ratio, but areas of velocity gradients are largest near the coupling point. Near the coupling point, the flow field is most nonuniform, which yields a highly periodic flow into the turbine inlet. Above the coupling point, the high velocity remains in the pressure-shell corner but separation is seen to develop at the highest speed ratio. At the turbine's inlet, reverse flow is seen at low speed ratios and is an indicator of flow leakage through the core. Velocity gradients are very large at low speed ratios. As the speed ratio increases to the coupling point, the high velocities remain on the shell side. Above the coupling point, the high-velocity flow migrates from the shell side to the core side. The mass flow rate decreases significantly and nonlinearly with the increase of the speed ratio, but for speed ratios greater than 1.000, the negative slope decreases.

  17. Recent developments of axial flow compressors under transonic flow conditions

    Science.gov (United States)

    Srinivas, G.; Raghunandana, K.; Satish Shenoy, B.

    2017-05-01

    The objective of this paper is to give a holistic view of the most advanced technology and procedures that are practiced in the field of turbomachinery design. Compressor flow solver is the turbulence model used in the CFD to solve viscous problems. The popular techniques like Jameson’s rotated difference scheme was used to solve potential flow equation in transonic condition for two dimensional aero foils and later three dimensional wings. The gradient base method is also a popular method especially for compressor blade shape optimization. Various other types of optimization techniques available are Evolutionary algorithms (EAs) and Response surface methodology (RSM). It is observed that in order to improve compressor flow solver and to get agreeable results careful attention need to be paid towards viscous relations, grid resolution, turbulent modeling and artificial viscosity, in CFD. The advanced techniques like Jameson’s rotated difference had most substantial impact on wing design and aero foil. For compressor blade shape optimization, Evolutionary algorithm is quite simple than gradient based technique because it can solve the parameters simultaneously by searching from multiple points in the given design space. Response surface methodology (RSM) is a method basically used to design empirical models of the response that were observed and to study systematically the experimental data. This methodology analyses the correct relationship between expected responses (output) and design variables (input). RSM solves the function systematically in a series of mathematical and statistical processes. For turbomachinery blade optimization recently RSM has been implemented successfully. The well-designed high performance axial flow compressors finds its application in any air-breathing jet engines.

  18. An adjustable flow restrictor for implantable infusion pumps based on porous ceramics.

    Science.gov (United States)

    Jannsen, Holger; Klein, Stephan; Nestler, Bodo

    2015-08-01

    This paper describes an adjustable flow restrictor for use in gas-driven implantable infusion pumps, which is based on the resistance of a flow through a porous ceramic material. The flow inside the walls of a ceramic tube can be adjusted between 270 nl/min and 1260 nl/min by changing the flow path length in the ceramic over a distance of 14 mm. The long-term stability of the flow restrictor has been analyzed. A drift of -8% from the nominal value was observed, which lies within the required tolerance of ±10% after 30 days. The average time needed to change the flow rate is 40 s. In addition, the maximum adjustment time was 110 s, which also lies within the specification.

  19. Fast Water Thermo-pumping Flow Across Nanotube Membranes for Desalination.

    Science.gov (United States)

    Zhao, Kuiwen; Wu, Huiying

    2015-06-10

    Development of high-efficiency and low-cost seawater desalination technologies is critical to meet global water crisis. Here we report a fast water pumping method in which the water molecules in seawater are continuously pumped across nanotube membranes driven by a small temperature difference, opening the possibility of high-throughput small-scale desalination devices driven by low-grade thermal energy. Using molecular dynamics simulations, we show that an equivalent driving pressure of 5.3 MPa is achieved with a temperature difference of only 15 K. The remarkable water pumping ability is attributed to the asymmetric thermal fluctuation of water molecules. With this method, a 10 cm(2) nanotube membrane with 1.5 × 10(13) pores per cm(2) will produce freshwater with a flow rate of 7.77 L/h under a small temperature difference of 15 K.

  20. Extended coherence lifetimes in microcavities under angle-resonant pumping conditions

    DEFF Research Database (Denmark)

    Østergaard, John Erland; Birkedal, Dan; Mizeikis, V.;

    2001-01-01

    processes by the final-state polariton population. Strong enhancements of the scattering processes have been observed as a result of up to several 100 polaritons per final k-state under angle-resonant pumping conditions (Erland et al, 2000; Stevenson et al, 2000). Energy and wave vector are conserved...

  1. Counter-rotating type axial flow pump unit in turbine mode for micro grid system

    Science.gov (United States)

    Kasahara, R.; Takano, G.; Murakami, T.; Kanemoto, T.; Komaki, K.

    2012-11-01

    Traditional type pumped storage system contributes to adjust the electric power unbalance between day and night, in general. This serial research proposes the hybrid power system combined the wind power unit with the pump-turbine unit, to provide the constant output for the grid system, even at the suddenly fluctuating/turbulent wind. In the pumping mode, the pump should operate unsteadily at not only the normal but also the partial discharge. The operation may be unstable in the rising portion of the head characteristics at the lower discharge, and/or bring the cavitation at the low suction head. To simultaneously overcome both weak points, the authors have proposed a superior pump unit that is composed of counter-rotating type impellers and a peculiar motor with double rotational armatures. This paper discusses the operation at the turbine mode of the above unit. It is concluded with the numerical simulations that this type unit can be also operated acceptably at the turbine mode, because the unit works so as to coincide the angular momentum change through the front runners/impellers with that thorough the rear runners/impellers, namely to take the axial flow at not only the inlet but also the outlet without the guide vanes.

  2. Optimal heat rejection pressure in transcritical carbon dioxide air conditioning and heat pump systems

    DEFF Research Database (Denmark)

    Liao, Shengming; Jakobsen, Arne

    1998-01-01

    Due to the urgent need for environmentally benign refrigerants, the use of the natural substance carbon dioxide in refrigeration systems has gained more and more attention. In systems such as automobile air-conditioners and heat pumps, owing to the relatively high heat rejection temperatures......, the cycles using carbon dioxide as refrigerant will have to operate in the transcritical area. In a transcritical carbon dioxide system, there is an optimal heat rejection pressure that gives a maximum COP. In this paper, it is shown that the value of this optimal heat rejection pressure mainly depends...... dioxide air conditioning or heat pump systems and for intelligent controlling such systems....

  3. Optimal heat rejection pressure in transcritical carbon dioxide air conditioning and heat pump systems

    DEFF Research Database (Denmark)

    Liao, Shengming; Jakobsen, Arne

    1998-01-01

    Due to the urgent need for environmentally benign refrigerants, the use of the natural substance carbon dioxide in refrigeration systems has gained more and more attention. In systems such as automobile air-conditioners and heat pumps, owing to the relatively high heat rejection temperatures...... dioxide air conditioning or heat pump systems and for intelligent controlling such systems......., the cycles using carbon dioxide as refrigerant will have to operate in the transcritical area. In a transcritical carbon dioxide system, there is an optimal heat rejection pressure that gives a maximum COP. In this paper, it is shown that the value of this optimal heat rejection pressure mainly depends...

  4. Evaluation of Flow-Induced Dynamic Stress and Vibration of Volute Casing for a Large-Scale Double-Suction Centrifugal Pump

    Directory of Open Access Journals (Sweden)

    Fu-Jun Wang

    2013-01-01

    Full Text Available The transient analysis was carried out to investigate the dynamic stress and vibration of volute casing for a large double-suction centrifugal pump by using the transient fluid-structure interaction theory. The flow pulsations at flow rate ranging from 60% to 100% of the nominal flow rate (Qd were taken as the boundary conditions for FEM analysis of the pump volute casing structure. The results revealed that, for all operating conditions, the maximum stress located at the volute tongue region, whereas the maximum vibration displacement happened close to the shaft hole region. It was also found that the blade passing frequency and its harmonics were dominant in the variations of dynamic stress and vibration displacement. The amplitude of the dominant frequency for the maximum stress detected at 0.6 Qd was 1.14 times that at Qd, lower than the related difference observed for pressure fluctuations (3.23 times. This study provides an effective method to quantify the flow-induced structural dynamic characteristics for a large-scale double-suction pump. It can be used to direct the hydraulic and structural design and stable operation, as well as fatigue life prediction for large-scale pumps.

  5. Analysis and control of flow at suction connection in high-speed centrifugal pump

    Directory of Open Access Journals (Sweden)

    Wen-wu Song

    2016-12-01

    Full Text Available The backflow vortexes at the suction connection in high-speed centrifugal pumps have negative effect on the flow field. Setting an orifice plate in front of the inducer is able to decrease the negative effect caused by backflow vortexes. The traditional plate is able to partially control the backflow vortexes, but a small part of the vortex is still in the inlet and the inducer. Four new types of orifice plates were created, and the control effects on backflow vortexes were analyzed. The ANSYS-CFX software was used to numerically simulate a high-speed centrifugal pump. The variations of streamline and velocity vectors at the suction connection were analyzed. Meanwhile, the effects of these plates on the impeller pressure and the internal flow field of the inducer were analyzed. Numerically, simulation and experimental data analysis methods were used to compare the head and efficiency of the high-speed pumps. The results show that the C-type orifice plate can improve the backflow vortex, reduce the low-pressure area, and improve the hydraulic performance of the high-speed pump.

  6. Determination of optimum working conditions R22 and R404A refrigerant mixtures in heat-pumps using Taguchi method

    Energy Technology Data Exchange (ETDEWEB)

    Comakli, K.; Simsek, F.; Comakli, O.; Sahin, B. [Ataturk University, Mechanical Engineering Department, 25240 Erzurum (Turkey)

    2009-11-15

    In this study, refrigerants R22 and R404A five of their binary mixtures which contain about 0%, 25%, 50%, 75% and 100% mass fractions of R404A were tested. It is investigated experimentally the effects of gas mixture rate, evaporator air inlet temperature (from 24 to 32 C), evaporator air mass flow rate (from 0.58 to 0.74 kg/s), condenser air inlet temperature (from 22 to 34 C) and condenser air mass flow rate (from 0.57 to 0.73 kg/s) on the coefficient of performance (COP) and exergetic efficiency values of vapor compression heat-pump systems. To determine the effect of the chosen parameters on the system and optimum working conditions, an experimental design method suggested by Genichi Taguchi was used. In this study, it was observed that the most effective parameters are found to be the condenser air inlet temperature for COP and exergetic efficiency. (author)

  7. Underground pumped storage hydroelectricity using abandoned works (deep mines or open pits) and the impact on groundwater flow

    Science.gov (United States)

    Pujades, Estanislao; Willems, Thibault; Bodeux, Sarah; Orban, Philippe; Dassargues, Alain

    2016-09-01

    Underground pumped storage hydroelectricity (UPSH) plants using open-pit or deep mines can be used in flat regions to store the excess of electricity produced during low-demand energy periods. It is essential to consider the interaction between UPSH plants and the surrounding geological media. There has been little work on the assessment of associated groundwater flow impacts. The impacts on groundwater flow are determined numerically using a simplified numerical model which is assumed to be representative of open-pit and deep mines. The main impact consists of oscillation of the piezometric head, and its magnitude depends on the characteristics of the aquifer/geological medium, the mine and the pumping and injection intervals. If an average piezometric head is considered, it drops at early times after the start of the UPSH plant activity and then recovers progressively. The most favorable hydrogeological conditions to minimize impacts are evaluated by comparing several scenarios. The impact magnitude will be lower in geological media with low hydraulic diffusivity; however, the parameter that plays the more important role is the volume of water stored in the mine. Its variation modifies considerably the groundwater flow impacts. Finally, the problem is studied analytically and some solutions are proposed to approximate the impacts, allowing a quick screening of favorable locations for future UPSH plants.

  8. Flow characteristics of the raw sewage for the design of sewage-source heat pump systems.

    Science.gov (United States)

    Xu, Ying; Wu, Yuebin; Sun, Qiang

    2014-01-01

    The flow characteristics of raw sewage directly affect the technical and economic performance of sewage-source heat pump systems. The purpose of this research is to characterize the flow characteristics of sewage by experimental means. A sophisticated and flexible experimental apparatus was designed and constructed. Then the flow characteristics of the raw sewage were studied through laboratorial testing and theoretical analyses. Results indicated that raw sewage could be characterized as a power-law fluid with the rheological exponent n being 0.891 and the rheological coefficient k being 0.00175. In addition, the frictional loss factor formula in laminar flow for raw sewage was deduced by theoretical analysis of the power-law fluid. Furthermore, an explicit empirical formula for the frictional loss factor in turbulent flow was obtained through curve fitting of the experimental data. Finally, the equivalent viscosity of the raw sewage is defined in order to calculate the Reynolds number in turbulent flow regions; it was found that sewage had two to three times the viscosity of water at the same temperature. These results contributed to appropriate parameters of fluid properties when designing and operating sewage-source heat pump systems.

  9. Numerical groundwater-flow modeling to evaluate potential effects of pumping and recharge: implications for sustainable groundwater management in the Mahanadi delta region, India

    Science.gov (United States)

    Sahoo, Sasmita; Jha, Madan K.

    2017-07-01

    Process-based groundwater models are useful to understand complex aquifer systems and make predictions about their response to hydrological changes. A conceptual model for evaluating responses to environmental changes is presented, considering the hydrogeologic framework, flow processes, aquifer hydraulic properties, boundary conditions, and sources and sinks of the groundwater system. Based on this conceptual model, a quasi-three-dimensional transient groundwater flow model was designed using MODFLOW to simulate the groundwater system of Mahanadi River delta, eastern India. The model was constructed in the context of an upper unconfined aquifer and lower confined aquifer, separated by an aquitard. Hydraulic heads of 13 shallow wells and 11 deep wells were used to calibrate transient groundwater conditions during 1997-2006, followed by validation (2007-2011). The aquifer and aquitard hydraulic properties were obtained by pumping tests and were calibrated along with the rainfall recharge. The statistical and graphical performance indicators suggested a reasonably good simulation of groundwater flow over the study area. Sensitivity analysis revealed that groundwater level is most sensitive to the hydraulic conductivities of both the aquifers, followed by vertical hydraulic conductivity of the confining layer. The calibrated model was then employed to explore groundwater-flow dynamics in response to changes in pumping and recharge conditions. The simulation results indicate that pumping has a substantial effect on the confined aquifer flow regime as compared to the unconfined aquifer. The results and insights from this study have important implications for other regional groundwater modeling studies, especially in multi-layered aquifer systems.

  10. Liquid metal flow control by DC electromagnetic pumps; Controle de vazao de metais liquidos por bombas eletromagneticas de corrente continua

    Energy Technology Data Exchange (ETDEWEB)

    Borges, Eduardo Madeira; Braz Filho, Francisco Antonio; Guimaraes, Lamartine Nogueira Frutuoso [Instituto de Estudos Avancados (IEAv), Sao Jose dos Campos, SP (Brazil)], e-mail: eduardo@ieav.cta.br, e-mail: fbraz@ieav.cta.br, e-mail: guimarae@ieav.cta.br

    2006-07-01

    The cooling system of high-density thermal power requires fluids of high thermal conductivity, such as liquid metals. Electromagnetic pumps can be used to liquid metal fluid flow control in cooling circuits. The operation of electromagnetic pumps used to flow control is based on Lorentz force. This force can be achieved by magnetic field and electric current interaction, controlled by external independent power supplies. This work presents the electromagnetic pump operational principles, the IEAv development scheme and the BEMC-1 simulation code. The theoretical results of BEMC-1 simulation are compared to electromagnetic pump operation experimental data, validating the BEMC-1 code. This code is used to evaluate the DC electromagnetic pump performance applied to Mercury flow control and others liquid metal such as Sodium, Lead and Bismuth, used in nuclear fast reactors. (author)

  11. Mathematical Modeling of Rotary Blood Pumps in a Pulsatile In Vitro Flow Environment.

    Science.gov (United States)

    Pirbodaghi, Tohid

    2017-01-18

    Nowadays, sacrificing animals to develop medical devices and receive regulatory approval has become more common, which increases ethical concerns. Although in vivo tests are necessary for development and evaluation of new devices, nonetheless, with appropriate in vitro setups and mathematical models, a part of the validation process can be performed using these models to reduce the number of sacrificed animals. The main aim of this study is to present a mathematical model simulating the hydrodynamic function of a rotary blood pump (RBP) in a pulsatile in vitro flow environment. This model relates the pressure head of the RBP to the flow rate, rotational speed, and time derivatives of flow rate and rotational speed. To identify the model parameters, an in vitro setup was constructed consisting of a piston pump, a compliance chamber, a throttle, a buffer reservoir, and the CentriMag RBP. A 40% glycerin-water mixture as a blood analog fluid and deionized water were used in the hydraulic circuit to investigate the effect of viscosity and density of the working fluid on the model parameters. First, model variables were physically measured and digitally acquired. Second, an identification algorithm based on regression analysis was used to derive the model parameters. Third, the completed model was validated with a totally different set of in vitro data. The model is usable for both mathematical simulations of the interaction between the pump and heart and indirect pressure measurement in a clinical context.

  12. Electro-pump Fault Diagnosis of Marine Ship by Vibration Condition Monitoring

    Directory of Open Access Journals (Sweden)

    Payman Salami

    2010-05-01

    Full Text Available The objective of this research is to investigate the correlation between vibration analysis and fault diagnosis. This was achieved by vibration analysis of an electro-pump of marine ship. The vibration analysis was initially run under regular interval during electro-pump life. Some series of tests were then conducted under the operating hours of stone crasher. Vibration data was regularly collected. The overall vibration data produced by vibration analysis was compared with previous data, in order to quantify the effectiveness of the results of vibration condition monitoring technique. Numerical data produced by vibration analysis were compared with vibration spectra in standard condition of healthy machine, in order to quantify the effectiveness of the vibration condition monitoring technique. The results of this paper have given more understanding on the dependent roles of vibration analysis in predicting and diagnosing machine faults.

  13. Flow Components in a NaK Test Loop Designed to Simulate Conditions in a Nuclear Surface Power Reactor

    Science.gov (United States)

    Polzin, Kurt A.; Godfroy, Thomas J.

    2008-01-01

    A test loop using NaK as the working fluid is presently in use to study material compatibility effects on various components that comprise a possible nuclear reactor design for use on the lunar surface. A DC electromagnetic (EM) pump has been designed and implemented as a means of actively controlling the NaK flow rate through the system and an EM flow sensor is employed to monitor the developed flow rate. These components allow for the matching of the flow rate conditions in test loops with those that would be found in a full-scale surface-power reactor. The design and operating characteristics of the EM pump and flow sensor are presented. In the EM pump, current is applied to a set of electrodes to produce a Lorentz body force in the fluid. A measurement of the induced voltage (back-EMF) in the flow sensor provides the means of monitoring flow rate. Both components are compact, employing high magnetic field strength neodymium magnets thermally coupled to a water-cooled housing. A vacuum gap limits the heat transferred from the high temperature NaK tube to the magnets and a magnetically-permeable material completes the magnetic circuit. The pump is designed to produce a pressure rise of 5 psi, and the flow sensor's predicted output is roughly 20 mV at the loop's nominal flow rate of 0.5 GPM.

  14. Application of modified k-ω model to predicting cavitating flow in centrifugal pump

    Directory of Open Access Journals (Sweden)

    Hou-lin LIU

    2013-07-01

    Full Text Available Considering the compressibility of the cavity in the cavitating flow, this paper presents a modified k-ω model for predicting the cavitating flow in a centrifugal pump, in which the modified k-ω model and Schnerr-Sauer cavitation model were combined with ANSYS CFX. To evaluate the modified and standard k-ω models, numerical simulations were performed with these two models, respectively, and the calculation results were compared with the experimental data. Numerical simulations were executed with three different values of the flow coefficient, and the simulation results of the modified k-ω model showed agreement with most of the experimental data. The cavitating flow in the centrifugal pump obtained by the modified k-ω model at the design flow coefficient of 0.102, was analyzed. When the cavitation number decreases, the cavity initially generates on the suction side of the blade near the leading edge and then expands to the outlet of the impeller, and the decrease of the total pressure coefficient mainly occurs upstream of the impeller passage, while the downstream remains almost unaffected by the development of cavitation.

  15. MHD interaction in an Electromagnetic Pump for high flow rate loop of ASTRID Sodium Fast Reactor secondary circuit -performances

    OpenAIRE

    Letout, S; Duterrail, Y; Fautrelle, Y; Medina, M. , il.; Rey, F.; Laffont, G.

    2015-01-01

    International audience; The present paper deals with the analysis of the performances of a very large Annular Linear Induction Pumps (ALIP) for liquid sodium. This pump is able to provide high flow rates (more than 7,000 m3.h-1 with a pressure discharge of about 3.7 bar). Dimensions of pumping channel under the active part are of an average diameter of 966 mm and a length of 4,500 mm. It’s a double sided inductor pump. On the base of an imposed 2D axisymmetric geometry, performances (discharg...

  16. Influence of fluid temperature gradient on the flow within the shaft gap of a PLR pump

    Science.gov (United States)

    Qian, W.; Rosic, B.; Zhang, Q.; Khanal, B.

    2016-03-01

    In nuclear power plants the primary-loop recirculation (PLR) pump circulates the high temperature/high-pressure coolant in order to remove the thermal energy generated within the reactor. The pump is sealed using the cold purge flow in the shaft seal gap between the rotating shaft and stationary casing, where different forms of Taylor-Couette flow instabilities develop. Due to the temperature difference between the hot recirculating water and the cold purge water (of order of 200 °C), the flow instabilities in the gap cause temperature fluctuations, which can lead to shaft or casing thermal fatigue cracks. The present work numerically investigated the influence of temperature difference and rotating speed on the structure and dynamics of the Taylor-Couette flow instabilities. The CFD solver used in this study was extensively validated against the experimental data published in the open literature. Influence of temperature difference on the fluid dynamics of Taylor vortices was investigated in this study. With large temperature difference, the structure of the Taylor vortices is greatly stretched at the interface region between the annulus gap and the lower recirculating cavity. Higher temperature difference and rotating speed induce lower fluctuating frequency and smaller circumferential wave number of Taylor vortices. However, the azimuthal wave speed remains unchanged with all the cases tested. The predicted axial location of the maximum temperature fluctuation on the shaft is in a good agreement with the experimental data, identifying the region potentially affected by the thermal fatigue. The physical understandings of such flow instabilities presented in this paper would be useful for future PLR pump design optimization.

  17. Ground-water system, estimation of aquifer hydraulic properties, and effects of pumping on ground-water flow in Triassic sedimentary rocks in and near Lansdale, Pennsylvania

    Science.gov (United States)

    Senior, Lisa A.; Goode, Daniel J.

    1999-01-01

    areas in three drainages, the Wissahickon, Towamencin, and Neshaminy Creeks.Ground-water flow was simulated for different pumping patterns representing past and current conditions. The three-dimensional numerical flow model (MODFLOW) was automatically calibrated by use of a parameter estimation program (MODFLOWP). Steady-state conditions were assumed for the calibration period of 1996. Model calibration indicates that estimated recharge is 8.2 inches (208 millimeters) and the regional anisotropy ratio for the sedimentary-rock aquifer is about 11 to 1, with permeability greatest along strike. The regional anisotropy is caused by up- and down-dip termination of high-permeability bed-oriented features, which were not explicitly simulated in the regional-scale model. The calibrated flow model was used to compare flow directions and capture zones in Lansdale for conditions corresponding to relatively high pumping rates in 1994 and to lower pumping rates in 1997. Comparison of the 1994 and 1997 simulations indicates that wells pumped at the lower 1997 rates captured less ground water from known sites of contamination than wells pumped at the 1994 rates. Ground-water flow rates away from Lansdale increased as pumpage decreased in 1997.A preliminary evaluation of the relation between ground-water chemistry and conditions favorable for the degradation of chlorinated solvents was based on measurements of dissolved-oxygen concentration and other chemical constituents in water samples from 92 wells. About 18 percent of the samples contained less than or equal to 5 milligrams per liter dissolved oxygen, a concentration that indicates reducing conditions favorable for degradation of chlorinated solvents.

  18. Evaluation of erythrocyte flow at a bearing gap in a hydrodynamically levitated centrifugal blood pump.

    Science.gov (United States)

    Murashige, Tomotaka; Kosaka, Ryo; Sakota, Daisuke; Nishida, Masahiro; Kawaguchi, Yasuo; Yamane, Takashi; Maruyama, Osamu

    2015-01-01

    We have developed a hydrodynamically levitated centrifugal blood pump for extracorporeal circulatory support. In the blood pump, a spiral groove bearing was adopted for a thrust bearing. In the spiral groove bearing, separation of erythrocytes and plasma by plasma skimming has been postulated to occur. However, it is not clarified that plasma skimming occurs in a spiral groove bearing. The purpose of this study is to verify whether plasma skimming occurs in the spiral groove bearing of a hydrodynamically levitated centrifugal blood pump. For evaluation of plasma skimming in the spiral groove bearing, an impeller levitation performance test using a laser focus displacement meter and a microscopic visualization test of erythrocyte flow using a high-speed microscope were conducted. Bovine blood diluted with autologous plasma to adjust hematocrit to 1.0% was used as a working fluid. Hematocrit on the ridge region in the spiral groove bearing was estimated using image analysis. As a result, hematocrits on the ridge region with gaps of 45 μm, 31 μm, and 25 μm were calculated as 1.0%, 0.6%, and 0.3%, respectively. Maximum skimming efficiency in this study was calculated as 70% with a gap of 25 μm. We confirmed that separation of erythrocyte and plasma occurred in the spiral groove bearing with decrease in bearing gap in a hydrodynamically levitated centrifugal blood pump.

  19. Alternative technique for implantation of biventricular support with HeartWare implantable continuous flow pump.

    Science.gov (United States)

    Krabatsch, Thomas; Stepanenko, Alexander; Schweiger, Martin; Kukucka, Marian; Ewert, Peter; Hetzer, Roland; Potapov, Evgenij

    2011-01-01

    In this case report, we describe a modification of the biventricular implantation of the HeartWare HVAD. A 28-year-old man with dilative cardiomyopathy presented with biventricular decompensation. The patient underwent implantation of two HeartWare HVADs for biventricular support. Because of low flow of the right pump (2 L/min), a right ventricular angiogram and repeated transesophageal echocardiography (TEE) were done and showed that the pump was compressing the right ventricle. Operative revision was performed, resulting in removal of the right pump and placement into the right atrium, so that it was located in the right pleural cavity. The HVAD fixation ring on the free wall of the right ventricle was left in place, and the opening was closed with an individually designed titanium plug. The findings of this case are that implantation of the HeartWare HVAD for right ventricular (RV) support may be safely performed in atrial position, with individually designed plugs allowing safe and quick removal of the HeartWare pump. This might be used as a "bail-out" strategy when necessary.

  20. Pump-turbines with constant flow direction; Pumpenturbinen mit gleicher Durchstroemrichtung

    Energy Technology Data Exchange (ETDEWEB)

    Mollenkopf, G. [Zentrale Forschung Engineering, KSB AG, Frankenthal (Germany)

    1997-12-31

    This research project was sponsored by the federal ministry of science and technology BMFT (product owner: New Materials and Chemical Technologies - NMT). Its aim was to develop a novel unit that can work both as a pump and a turbine with a constant flow direction through internal blade adjustment. This specifically high-speed pump-turbine is suited for plants where a liquid in one case needs to be hauled against a rising pressure and where, in another case, there is a pressure drop in the same direction. So far, either a separate pump and turbine each are used which are temporarily stopped, involving corresponding effort, or - almost as a rule - the turbine is dispensed with, so that the energy locked up in the pressure drop goes unused. (orig.) [Deutsch] Die Zielsetzung unseres Forschungsvorhabens, das vom BMFT (Produkttraeger: Neue Materialien und Chemische Technologien - NMT) gefoerdert wird, war die Entwicklung eines neuartigen Aggregats, das durch interne Schaufelverstellung in der Lage ist, sowohl als Pumpe als auch als Turbine mit gleichbleibender Durchstroemrichtung zu arbeiten. Diese spezifisch schnellaeufige Pumpturbine kommt fuer Anlagen in Frage, in denen eine Fluessigkeit im einen Fall gegen einen anstehenden Druck gefoerdert werden muss und im anderen Fall in gleicher Richtung ein Druckgefaelle zur Verfuegung steht. Entweder werden bisher getrennt aufgestellte Pumpen und Turbinen mit zeitweisem Stillstand und entsprechendem Aufwand eingesetzt oder es wird - fast in der Regel - auf die Turbine und damit auf die im Druckgefaelle enthaltene Energie verzichtet. (orig.)

  1. Impact of the postpump resistance on pressure-flow waveform and hemodynamic energy level in a neonatal pulsatile centrifugal pump.

    Science.gov (United States)

    Wang, Shigang; Haines, Nikkole; Richardson, J Scott; Dasse, Kurt A; Undar, Akif

    2009-01-01

    This study tested the impact of different postpump resistances on pulsatile pressure-flow waveforms and hemodynamic energy output in a mock extracorporeal system. The circuit was primed with a 40% glycerin-water mixture, and a PediVAS centrifugal pump was used. The pre- and postpump pressures and flow rates were monitored via a data acquisition system. The postpump resistance was adjusted using a Hoffman clamp at the outlet of the pump. Five different postpump resistances and rotational speeds were tested with nonpulsatile (NP: 5000 RPM) and pulsatile (P: 4000 RPM) modes. No backflow was found when using pulsatile flow. With isoresistance, increased arterial resistances decreased pump flow rates (NP: from 1,912 ml/min to 373 ml/min; P: from 1,485 ml/min to 288 ml/min), increased postpump pressures (NP: from 333 mm Hg to 402 mm Hg; P: from 223 mm Hg to 274 mm Hg), and increased hemodynamic energy output with pulsatile mode. Pump flow rate correlated linearly with rotational speed (RPMs) of the pump, whereas postpump pressures and hemodynamic energy outputs showed curvilinear relationships with RPMs. The maximal pump flow rate also increased from 618 ml/min to 4,293 ml/min with pulsatile mode and from 581 ml/min to 5,665 ml/min with nonpulsatile mode. Results showed that higher postpump resistance reduced the pump flow range, and increased postpump pressure and surplus hemodynamic energy output with pulsatile mode. Higher rotational speeds also generated higher pump flow rates, postpump pressures, and increased pulsatility.

  2. Numerical Investigation of Velocity Flow Field inside an Impeller Air Model of a Centrifugal Pump with Vaned Diffuser Interactions and Comparison with PIV Measurements

    Directory of Open Access Journals (Sweden)

    Abdelmadjid Atif

    2010-01-01

    Full Text Available The paper refers to the analysis of interactions between the impeller and the vaned diffuser on the air model of a radial flow pump. The study deals with a numerical simulation of the flow for a full 360° entire impeller and diffuser. The task is carried out close to design operating conditions and for one particular position of the impeller blade with respect to diffuser frame. Among all the results, it has been decided to mainly focus on the flow pattern at the exit part inside the impeller coming from the diffuser vanes interactions. The results are compared to the available PIV measurements.

  3. A study of pumps for the Hot Dry Rock Geothermal Energy extraction experiment (LTFT (Long Term Flow Test))

    Energy Technology Data Exchange (ETDEWEB)

    Tatro, C.A.

    1986-10-01

    A set of specifications for the hot dry rock (HDR) Phase II circulation pumping system is developed from a review of basic fluid pumping mechanics, a technical history of the HDR Phase I and Phase II pumping systems, a presentation of the results from experiment 2067 (the Initial Closed-Loop Flow Test or ICFT), and consideration of available on-site electrical power limitations at the experiment site. For the Phase II energy extraction experiment (the Long Term Flow Test or LTFT) it is necessary to provide a continuous, low maintenance, and highly efficient pumping capability for a period of twelve months at variable flowrates up to 420 gpm and at surface injection pressures up to 5000 psi. The pumping system must successfully withstand attacks by corrosive and embrittling gases, erosive chemicals and suspended solids, and fluid pressure and temperature fluctuations. In light of presently available pumping hardware and electric power supply limitations, it is recommended that positive displacement multiplex plunger pumps, driven by variable speed control electric motors, be used to provide the necessary continuous surface injection pressures and flowrates for LTFT. The decision of whether to purchase the required circulation pumping hardware or to obtain contractor provided pumping services has not been made.

  4. Effect of warming and flow rate conditions of blood warmers on red blood cell integrity.

    Science.gov (United States)

    Poder, T G; Pruneau, D; Dorval, J; Thibault, L; Fisette, J-F; Bédard, S K; Jacques, A; Beauregard, P

    2016-11-01

    Fluid warmers are routinely used to reduce the risk of hypothermia and cardiac complications associated with the infusion of cold blood products. However, warming blood products could generate haemolysis. This study was undertaken to compare the impact of temperature of blood warmers on the per cent haemolysis of packed red blood cells (RBCs) heated at different flow rates as well as non-flow conditions. Infusion warmers used were calibrated at 41·5°C ± 0·5°C and 37·5°C ± 0·5°C. Cold RBC units stored at 4°C in AS-3 (n = 30), aged 30-39 days old, were divided into half units before being allocated under two different scenarios (i.e. infusion pump or syringe). Blood warmers were effective to warm cold RBCs to 37·5°C or 41·5°C when used in conjunction with an infusion pump at flow rate up to 600 ml/h. However, when the warmed blood was held in a syringe for various periods of time, such as may occur in neonatal transfusions, the final temperature was below the expected requirements with measurement as low as 33·1°C. Increasing the flow with an infusion pump increased haemolysis in RBCs from 0·2% to up to 2·1% at a flow rate of 600 ml/h regardless of the warming device used (P < 0·05). No relevant increase of haemolysis was observed using a syringe. The use of a blood warmer adjusted to 41·5°C is probably the best choice for reducing the risk of hypothermia for the patient without generating haemolysis. However, we should be cautious with the use of an infusion pump for RBC transfusion, particularly at high flow rates. © 2016 International Society of Blood Transfusion.

  5. A Micro-PIV Study of the Pulsed Micro-Flows Driven by an Insulin Pump

    Science.gov (United States)

    Wang, Bing; Demuren, Ayodeji; Gyuricsko, Eric; Hu, Hui

    2009-11-01

    In recent years, there is a surge in the popularity of using insulin pump or continuous subcutaneous insulin infusion therapy, as opposed to multiple daily injections by insulin syringe or an insulin pen. Some case studies have suggested that insulin delivery failure may be caused by precipitation of insulin within the infusion set. Speculation also exists that the flow of insulin through an insulin infusion set may be reduced or inhibited by air bubbles entrained into the micro-sized tubing system since there are chances that air be introduced into the insulin reservoir during the filling process. In the present study, a microscopic Particle Image Velocimtry (micro-PIV) system was used to characterize the transient behavior of the pulsed micro-flows inside the micro-sized tubing system of an insulin infusion set with insulin pump operating in basal mode (i.e., pulsed insulin pumping). The effects of the air bubbles entrained into the micro-sized tubing system on the insulin delivery process were assessed based on the micro-PIV measurements.

  6. A versatile tool to energy efficiency. Pumps in cooling and air-conditioning appliances; Vielseitige Schluessel zur Energieeffizienz. Pumpen in der Kaelte- und Klimatechnik

    Energy Technology Data Exchange (ETDEWEB)

    Anon.

    2012-10-15

    Pumps are ubiquitous in refrigeration systems and air conditioning systems. Pumps are present in large numbers particularly in large buildings with correspondent cooling demand. The used pump technology has a significant impact on the energy consumption and thus also on the efficiency of the entire system. Thus a look at the various pump types and their applications as well as electricity consumption is worthwhile. The pump expert WILO SE (Dortmund, Federal Republic of Germany) explains the basic fundamentals of pump technology.

  7. Application analysis of ground source heat pumps in building space conditioning

    Energy Technology Data Exchange (ETDEWEB)

    Qian, Hua; Wang, Yungang

    2013-07-01

    The adoption of geothermal energy in space conditioning of buildings through utilizing ground source heat pump (GSHP, also known as geothermal heat pump) has increased rapidly during the past several decades. However, the impacts of the GSHP utilization on the efficiency of heat pumps and soil temperature distribution remained unclear and needs further investigation. This paper presents a novel model to calculate the soil temperature distribution and the coefficient of performance (COP) of GSHP. Different scenarios were simulated to quantify the impact of different factors on the GSHP performance, including heat balance, daily running mode, and spacing between boreholes. Our results show that GSHP is suitable for buildings with balanced cooling and heating loads. It can keep soil temperature at a relatively constant level for more than 10 years. Long boreholes, additional space between boreholes, intermittent running mode will improve the performance of GSHP, but large initial investment is required. The improper design will make the COP of GSHP even lower than traditional heat pumps. Professional design and maintenance technologies are greatly needed in order to promote this promising technology in the developing world.

  8. Initial hydrodynamic study on a new intraaortic axial flow pump: Dynamic aortic valve

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Rotary blood pumps have been researched as implantableventricular assist devices for years. To further reduce the complex of implanted axial pumps, the authors proposed a new concept of intraaortic axial pump, termed previously as "dynamic aortic valve (DAV)". Instead of being driven by an intraaortic micro-electric motor, it was powered by a magnetic field from outside of body. To ensure the perfusion of coronary artery, the axial flow pump is to be implanted in the position of aortic valve. It could serve as either a blood pump or a mechanical valve depending on the power input. This research tested the feasibility of the new concept in model study. A column, made from permanent magnet, is jointed to an impeller in a concentric way to form a "rotor-impeller". Supported by a hanging shaft cantilevered in the center of a rigid cage, the rotor-impeller can be turned by the magnetic field in the surrounding space. In the present prototype, the rotor is 8 mm in diameter and 15 mm in length, the impeller has 3 vanes with an outer diameter of 18 mm. The supporting cage is 22 mm in outer diameter and 20 mm in length. When tested, the DAV prototype is inserted into the tube of a mock circuit. The alternative magnetic field is produced by a rotating magnet placed side by side with the rotor-impeller at a distance of 30 mm. Once the alternative magnetic field is presented in the surrounding space, the DAV starts to turn, leading to a pressure difference and liquid flow in the tube. The flow rate or pressure difference is proportioned to rotary speed. At the maximal output of hydraulic power, the flow rate reached 5 L/min against an afterload of 100 mmHg. The maximal pressure difference generated by DAV at a rotation rate of 12600 r/min was 147 mmHg. The preliminary results demonstrated the feasibility of "DAV", further research on this concept is justifiable.

  9. Groundwater Management Policies for Maintaining Stream Flow Given Variable Climatic Conditions

    Science.gov (United States)

    Pohll, G.; Carroll, R. W.; Brozovic, N.

    2012-12-01

    Groundwater is an important resource to agriculture throughout the semi-arid United States, where farmers often supplement surface water diversions with groundwater pumping. Understanding the complex exchange over space and time between rivers and aquifers is important in developing management alternatives that are capable of preserving stream flow for habitat and increasing water deliveries downstream while minimizing lost crop production. Previous integrated hydrologic-economic models have generally assumed superposition of the impacts of groundwater pumping on the hydrologic system for analytical tractability. Although this assumption may be reasonable for some surface water-groundwater systems, in many systems the behavior diverges considerably from the linear assumption. We present analyses using an integrated hydrologic-economic model of surface water-groundwater interaction with nonlinear dynamics, developed for the Mason Valley area in Nevada. The study area has active water conflict between upstream and downstream water users, where groundwater pumping has an important impact on streamflow. The model replicates the movement of water throughout the coupled river and aquifer of the Walker River system and is used to analyze hypothetical tradeoffs between increasing streamflow at the basin outlet and meeting crop water demands for irrigation. The model is run from 1997 to 2006 to capture wet and dry climatic conditions, including a four year drought period in which groundwater pumping accounts for more than 50% of the irrigated water budget. Three alternate groundwater management policies are analyzed to compare economic performance (resulting from reductions in crop area due to reduced groundwater pumping) and hydrologic impact (in terms of increased stream discharge at the basin outlet). First, uniform pumping quotas are the simplest policy to implement and are modeled here as equal reductions in groundwater pumping for each stakeholder at a lumped field

  10. Numerical Investigations of Unsteady Flow in a Centrifugal Pump with a Vaned Diffuser

    Directory of Open Access Journals (Sweden)

    Olivier Petit

    2013-01-01

    Full Text Available Computational fluid dynamics (CFD analyses were made to study the unsteady three-dimensional turbulence in the ERCOFTAC centrifugal pump test case. The simulations were carried out using the OpenFOAM Open Source CFD software. The test case consists of an unshrouded centrifugal impeller with seven blades and a radial vaned diffuser with 12 vanes. A large number of measurements are available in the radial gap between the impeller and the diffuse, making this case ideal for validating numerical methods. Results of steady and unsteady calculations of the flow in the pump are compared with the experimental ones, and four different turbulent models are analyzed. The steady simulation uses the frozen rotor concept, while the unsteady simulation uses a fully resolved sliding grid approach. The comparisons show that the unsteady numerical results accurately predict the unsteadiness of the flow, demonstrating the validity and applicability of that methodology for unsteady incompressible turbomachinery flow computations. The steady approach is less accurate, with an unphysical advection of the impeller wakes, but accurate enough for a crude approximation. The different turbulence models predict the flow at the same level of accuracy, with slightly different results.

  11. Compare Energy Use in Variable Refrigerant Flow Heat Pumps Field Demonstration and Computer Model

    Energy Technology Data Exchange (ETDEWEB)

    Sharma, Chandan; Raustad, Richard

    2013-07-01

    Variable Refrigerant Flow (VRF) heat pumps are often regarded as energy efficient air-conditioning systems which offer electricity savings as well as reduction in peak electric demand while providing improved individual zone setpoint control. One of the key advantages of VRF systems is minimal duct losses which provide significant reduction in energy use and duct space. However, there is limited data available to show their actual performance in the field. Since VRF systems are increasingly gaining market share in the US, it is highly desirable to have more actual field performance data of these systems. An effort was made in this direction to monitor VRF system performance over an extended period of time in a US national lab test facility. Due to increasing demand by the energy modeling community, an empirical model to simulate VRF systems was implemented in the building simulation program EnergyPlus. This paper presents the comparison of energy consumption as measured in the national lab and as predicted by the program. For increased accuracy in the comparison, a customized weather file was created by using measured outdoor temperature and relative humidity at the test facility. Other inputs to the model included building construction, VRF system model based on lab measured performance, occupancy of the building, lighting/plug loads, and thermostat set-points etc. Infiltration model inputs were adjusted in the beginning to tune the computer model and then subsequent field measurements were compared to the simulation results. Differences between the computer model results and actual field measurements are discussed. The computer generated VRF performance closely resembled the field measurements.

  12. Automated low-flow ascites pump for the treatment of cirrhotic patients with refractory ascites

    Science.gov (United States)

    Stirnimann, Guido; Banz, Vanessa; Storni, Federico; De Gottardi, Andrea

    2017-01-01

    Cirrhotic patients with refractory ascites (RA) can be treated with repeated large volume paracentesis (LVP), with the insertion of a transjugular intrahepatic portosystemic shunt (TIPS) or with liver transplantation. However, side effects and complications of these therapeutic options, as well as organ shortage, warrant the development of novel treatments. The automated low-flow ascites pump (alfapump®) is a subcutaneously-implanted novel battery-driven device that pumps ascitic fluid from the peritoneal cavity into the urinary bladder. Ascites can therefore be aspirated in a time- and volume-controlled mode and evacuated by urination. Here we review the currently available data about patient selection, efficacy and safety of the alfapump and provide recommendations for the management of patients treated with this new method. PMID:28203285

  13. Different elution modes and field programming in gravitational field-flow fractionation. III. Field programming by flow-rate gradient generated by a programmable pump.

    Science.gov (United States)

    Plocková, J; Chmelík, J

    2001-05-25

    Gravitational field-flow fractionation (GFFF) utilizes the Earth's gravitational field as an external force that causes the settlement of particles towards the channel accumulation wall. Hydrodynamic lift forces oppose this action by elevating particles away from the channel accumulation wall. These two counteracting forces enable modulation of the resulting force field acting on particles in GFFF. In this work, force-field programming based on modulating the magnitude of hydrodynamic lift forces was implemented via changes of flow-rate, which was accomplished by a programmable pump. Several flow-rate gradients (step gradients, linear gradients, parabolic, and combined gradients) were tested and evaluated as tools for optimization of the separation of a silica gel particle mixture. The influence of increasing amount of sample injected on the peak resolution under flow-rate gradient conditions was also investigated. This is the first time that flow-rate gradients have been implemented for programming of the resulting force field acting on particles in GFFF.

  14. Performance Analysis of Air-to-Water Heat Pump in Latvian Climate Conditions

    Science.gov (United States)

    Kazjonovs, Janis; Sipkevics, Andrejs; Jakovics, Andris; Dancigs, Andris; Bajare, Diana; Dancigs, Leonards

    2014-12-01

    Strategy of the European Union in efficient energy usage demands to have a higher proportion of renewable energy in the energy market. Since heat pumps are considered to be one of the most efficient heating and cooling systems, they will play an important role in the energy consumption reduction in buildings aimed to meet the target of nearly zero energy buildings set out in the EU Directive 2010/31/EU. Unfortunately, the declared heat pump Coefficient of Performance (COP) corresponds to a certain outdoor temperature (+7 °C), therefore different climate conditions, building characteristics and settings result in different COP values during the year. The aim of this research is to investigate the Seasonal Performance factor (SPF) values of air-to-water heat pump which better characterize the effectiveness of heat pump in a longer selected period of time, especially during the winter season, in different types of residential buildings in Latvian climate conditions. Latvia has four pronounced seasons of near-equal length. Winter starts in mid-December and lasts until mid-March. Latvia is characterized by cold, maritime climate (duration of the average heating period being 203 days, the average outdoor air temperature during the heating period being 0.0 °C, the coldest five-day average temperature being -20.7 °C, the average annual air temperature being +6.2 °C, the daily average relative humidity being 79 %). The first part of this research consists of operational air-towater heat pump energy performance monitoring in different residential buildings during the winter season. The second part of the research takes place under natural conditions in an experimental construction stand which is located in an urban environment in Riga, Latvia. The inner area of this test stand, where air-to-water heat pump performance is analyzed, is 9 m2. The ceiling height is 3 m, all external wall constructions (U = 0.16 W/(m2K)) have ventilated facades. To calculate SPF, the

  15. Pulsatile flow and simple flow control method during weaning period in centrifugal pump: toward more expanded usage in open heart surgery.

    Science.gov (United States)

    Nishida, H; Koyanagi, H; Endo, M; Suzuki, S; Oshiyama, H; Nojiri, C; Fukasawa, H; Akutsu, T

    1994-09-01

    To expand the usage of the centrifugal pump (CP) in open heart surgery, we performed two studies. In the first, we evaluated pulsatile flow in the CP. In vitro pump performance of the Terumo Capiox pump (TCP) and the Sarns Delphin pump (SDP) and increase of free hemoglobin (mg/dl) after driving 6 h were investigated using bovine blood. A roller pump (RP) was used as a comparison. Equally effective pulsatile flow was obtained in both CPs. Hemolysis was less severe in TCP (120 mg/dl) than SDP (210 mg/dl) and RP (320 mg/dl). In the second study, we evaluated a simple flow control method. Flow rate was easily controlled with step-wise clamping of 3-pronged tubing (Triple-flow) without changing rotational speed, regardless of afterload. Fluctuation of flow was much less with this method than with the rotational speed change method. The use of pulsatile flow of TCP, with its minimum increase of hemolysis and the easier flow control method during the weaning process, may expand the usage of CP in open heart surgery.

  16. Hydroacoustic simulation of rotor-stator interaction in resonance conditions in Francis pump-turbine

    Energy Technology Data Exchange (ETDEWEB)

    Nicolet, C [Power Vision Engineering sarl, Ch. des Champs-Courbes 1, CH-1024 Ecublens (Switzerland); Ruchonnet, N; Alligne, S; Avellan, F [EPFL Laboratory for Hydraulic Machines, Av. de Cour 33bis, CH-1007 Lausanne (Switzerland); Koutnik, J, E-mail: christophe.nicolet@powervision-eng.c [Voith Hydro Holding GmbH and Co. KG, Alexanderstr. 11, 89522 Heidenheim (Germany)

    2010-08-15

    Combined effect of rotating pressure field related to runner blade and wakes of wicket gates leads to rotor stator interactions, RSI, in Francis pump-turbines. These interactions induce pressures waves propagating in the entire hydraulic machine. Superposition of those pressure waves may result in standing wave in the spiral casing and rotating diametrical mode in the guide vanes and can cause strong pressure fluctuations and vibrations. This paper presents the modeling, simulation and analysis of Rotor-Stator Interaction of a scale model of a Francis pump-turbine and related test rig using a one-dimensional approach. The hydroacoustic modeling of the Francis pump-turbine takes into account the spiral casing, the 20 guide vanes, the 9 rotating runner vanes. The connection between stationary and rotating parts is ensured by a valve network driven according to the unsteady flow distribution between guide vanes and runner vanes. Time domain simulations are performed for 2 different runner rotational speeds in turbine mode. The simulation results are analyzed in frequency domain and highlights hydroacoustic resonance between RSI excitations and the spiral case. Rotating diametrical mode in the vaneless gap and standing wave in the spiral case are identified. The influence of the resonance on phase and amplitude of pressure fluctuations obtained for both the spiral case and the vaneless gap is analyzed. The mode shape and frequencies are confirmed using eigenvalues analysis.

  17. Study of Peak Expiratory Flow Rate as the Assessment of Lung Function in Occupationally Exposed Petrol Pump Workers of Western Maharashtra

    Directory of Open Access Journals (Sweden)

    Patil Smita V

    2016-04-01

    Full Text Available Background: Fast urbanization trends, rapid industrial growth, globalization, and poor environmental conditions at work places have created a lot of healthrelated issues. Aim and Objectives: The aim of this study is to investigate Peak Expiratory Flow Rate (PEFR as the assessment of lung function in occupationally exposed petrol pump workers and also check whether PEFR increases or decreases with duration of exposure. Material and Methods: The study was conducted on 60 male petrol pump workers between age group of 20-40 years who were working as petrol filling attendants for more than one year from western Maharashtra. 50 normal healthy males with same socioeconomic status were chosen as controls to find out the effect of occupational exposure to petroleum product on PEFR as the assessment of lung function tests. Petrol pump workers were divided into three groups based on their duration of exposure i.e. 1- 5 yrs, 6- 10 yrs and more than 11 years. PEFR of petrol pump workers and control was measured by using a Mini Wright peak flow meter which is a portable device for measuring ventilator functions. Comparisons was done using unpaired t-test for 2 groups comparisons and one way ANOVAfor multiple groups of exposures. Results: The PEFR was significantly lower decrease (p=0.001 around petrol pump workers (389.17 as compared to control (534.2. As year of exposure increased mean value of PEFR was significantly decreased from 452.17, 378.00 and 283.64 respectively in petrol pump workers. Conclusion: The results suggested that respiratory functions i.e. PEFR of occupationally exposed petrol pump workers are significantly reduced as compared to controls, also PEFR is significantly reduced with increase in the duration of exposure.

  18. Flow Field Characteristics Analysis of Axial Flow Pump Based on CFD%基于 CFD的轴流泵流场特性分析

    Institute of Scientific and Technical Information of China (English)

    曹婷; 郑源

    2014-01-01

    For more further research on axial-flow pump,learning pump running under different conditions and to further emphasizing the impor-tance of optimal conditions running,combined with a model pump data in South-to-North Water Transfer Project,the model pump were numerically simulated by using CFD software Fluent with multiple reference system coordinates were chosen and based on the S-A turbulence model. Axial flow pump hydraulic performance under different conditions were estimated by calculating,the external characteristic curve were drawn. Compared with the experimental result,they were approximate,showing the simulation’s accuracy. The pressure and velocity distribution of blade and guide vanes were analyzed based on the result of the numerical simulation. Some laws of blade and guide vanes’flow pattern under different conditions were showed,the bland pressure was increased in the radial. The magnitude of relative velocity presented cylindrical surface distribution increased from hub to rim. The pressure of Guide vanes was presented as zonal distribution and water flowed out along the axial finally.%为更深入研究轴流泵,了解不同工况下轴流泵的运行状态,进一步强调最优工况运行的重要性,结合南水北调工程中某泵站模型的数据,采用流体力学软件Fluent,在多重参考坐标系下,选用S-A湍流模型对模型泵进行数值模拟。通过计算,对不同工况下的轴流泵水力性能进行了预估,绘制了轴流泵的特性曲线,与试验值进行比较,吻合较好,说明了数值模拟的准确性。根据数值计算结果,分析了轴流泵叶轮叶片和导叶叶片表面的速度及压力分布,揭示了叶片和导叶表面流态和压力的分布规律:叶片压力径向递增,相对速度由轮毂到轮缘逐渐加快,按圆柱面分布,导叶表面压力呈带状分布,水流最终从导叶出口沿轴向流出。

  19. SHINE Vacuum Pump Test Verification

    Energy Technology Data Exchange (ETDEWEB)

    Morgan, Gregg A; Peters, Brent

    2013-09-30

    Normetex pumps used world-wide for tritium service are no longer available. DOE and other researchers worldwide have spent significant funds characterizing this pump. Identification of alternate pumps is required for performance and compatibility with tritium gas. Many of the pumps that could be used to meet the functional performance requirements (e.g. pressure and flow conditions) of the Normetex pump have features that include the use of polymers or oils and greases that are not directly compatible with tritium service. This study assembles a test system to determine the flow characteristics for candidate alternate pumps. These tests are critical to the movement of tritium through the SHINE Tritium Purification System (TPS). The purpose of the pump testing is two-fold: (1) obtain baseline vacuum pump characteristics for an alternate (i.e. ''Normetex replacement'') pump intended for use in tritium service; and (2) verify that low pressure hydrogen gas can be transported over distances up to 300 feet by the candidate pumps. Flow rates and nominal system pressures have been identified for the SHINE Mo-99 production process Tritium Purification System (TPS). To minimize the line sizes for the transfer of low pressure tritium from the Neutron Driver Accelerator System (NDAS) to the primary processing systems in the TPS, a ''booster'' pump has been located near the accelerator in the design. A series of pump tests were performed at various configurations using hydrogen gas (no tritium) to ensure that this concept is practical and maintains adequate flow rates and required pressures. This report summarizes the results of the tests that have been performed using various pump configurations. The current design of the Tritium Purification System requires the ''booster'' pump to discharge to or to be backed by another vacuum pump. Since Normetex pumps are no longer manufactured, a commercially available Edwards

  20. Stratification and mixing in Lake Elsinore, California: an assessment of axial flow pumps for improving water quality in a shallow eutrophic lake.

    Science.gov (United States)

    Lawson, Rebecca; Anderson, Michael A

    2007-11-01

    A 3-year study was conducted to quantify the effectiveness of a destratification system on weakening thermal stratification and increasing dissolved oxygen (DO) levels in Lake Elsinore, California. Biweekly measurements of temperature, DO, and other parameters were made at 14 sites across the lake beginning in July 2003. A destratification system consisting of 20 axial flow pumps fitted with 3 HP electric motors and 1.8m diameter impellers mounted 2m below the water surface was installed in the spring of 2004 and made fully operational in July 2004. An unusually wet winter of 2005 raised the summer mean depth from 3.0m in 2004 to 6.7 m in 2005. This study thus allowed us to quantify the influence of axial flow pump operation on water column properties under shallow water conditions (i.e., before and after axial flow pump installation), and also to compare the effectiveness of the destratification system at two strongly different lake levels. Transparencies increased substantially after the winter storms in 2005 and thermal stability was shown to be strongly dependent upon lake level. Stratification and a large area of anoxic sediments persisted despite pump operation in the summers of 2004 and 2005. Acoustic Doppler current profiler (ADCP) measurements showed that mixing energy was not being efficiently transmitted laterally into the water column.

  1. Groundwater flow to a pumping well in a sloping fault zone unconfined aquifer

    Science.gov (United States)

    Huang, Ching-Sheng; Yang, Shaw-Yang; Yeh, Hund-Der

    2014-05-01

    This study develops a mathematical model for simulating the hydraulic head distribution in response to pumping in a sloping fault zone aquifer under a water table boundary condition. A two-dimensional equation with a sink term representing the pumping is used for describing the head distribution in the aquifer. In addition, a first-order free surface equation is adopted to represent the change in water table at the outcrop. The analytical solution of the model, derived by the Laplace and finite Fourier cosine transforms, is expressed in terms of a double series. A finite difference solution within a deformable grid framework is developed to assess the solution obtained by specifying the free surface equation at the outcrop. Based on the analytical solution, we have found that the model's prediction tends to overestimate drawdown in a late pumping period. The temporal head distribution is independent of the aquifer slope if the water table change is small, and exhibits a double-humped shape due to the effect of the free surface. The temporal drawdown predicted from the analytical solution is further compared with those measured from a pumping test conducted in northern Portugal.

  2. Behavior of primary coolant pump shaft seals during station blackout conditions

    Energy Technology Data Exchange (ETDEWEB)

    Hill, R.C.; Rhodes, D.B.

    1986-09-12

    An assessment is made of the ability of typical Reactor Coolant Pump (RCP) Shaft Seals to withstand the conditions predicted for a station blackout (loss of all alternating current power) at a nuclear power station. Several factors are identified that are key to seal stability including inlet fluid conditions, pressure downstream of the seal, and geometrical details of the seal rings. Limits for stable seal operation are determined for various combinations of these factors, and the conclusion is drawn that some RPC seals would be near the threshold of instability during a station blackout. If the threshold were exceeded, significant leakage of coolant from the primary coolant system could be expected.

  3. Heat pump air conditioning system for pure electric vehicle at ultra-low temperature

    Directory of Open Access Journals (Sweden)

    Li Hai-Jun

    2014-01-01

    Full Text Available When the ordinary heat pump air conditioning system of a pure electric vehicle runs at ultra-low temperature, the discharge temperature of compressor will be too high and the heating capacity of the system will decay seriously, it will lead to inactivity of the heating system. In order to solve this problem, a modification is put forward, and an experiment is also designed. The experimental results show that in the same conditions, this new heating system increases more than 20% of the heating capacity; when the outside environment temperature is negative 20 degrees, the discharge temperature of compressor is below 60 degrees.

  4. Clinical effectiveness of centrifugal pump to produce pulsatile flow during cardiopulmonary bypass in patients undergoing cardiac surgery.

    Science.gov (United States)

    Gu, Y John; van Oeveren, Willem; Mungroop, Hubert E; Epema, Anne H; den Hamer, Inez J; Keizer, Jorrit J; Leuvenink, Ron P; Mariani, Massimo A; Rakhorst, Gerhard

    2011-02-01

    Although the centrifugal pump has been widely used as a nonpulsatile pump for cardiopulmonary bypass (CPB), little is known about its performance as a pulsatile pump for CPB, especially on its efficacy in producing hemodynamic energy and its clinical effectiveness. We performed a study to evaluate whether the Rotaflow centrifugal pump produces effective pulsatile flow during CPB and whether the pulsatile flow in this setting is clinically effective in adult patients undergoing cardiac surgery. Thirty-two patients undergoing CPB for elective coronary artery bypass grafting were randomly allocated to a pulsatile perfusion group (n = 16) or a nonpulsatile perfusion group (n = 16). All patients were perfused with the Rotaflow centrifugal pump. In the pulsatile group, the centrifugal pump was adjusted to the pulsatile mode (60 cycles/min) during aortic cross-clamping, whereas in the nonpulsatile group, the pump was kept in its nonpulsatile mode during the same period of time. Compared with the nonpulsatile group, the pulsatile group had a higher pulse pressure (P centrifugal pump is associated with a small gain of EEP and SHE, which does not seem to be clinically effective in adult cardiac surgical patients.

  5. The High Reynolds Number Flow Through an Axial-Flow Pump

    Science.gov (United States)

    1993-11-01

    velocity field. After some initial computations of the flow field using a viscous form of the code of Adamczyk, Mulac, and Celestina [1986] at a low Mach...Simulating Flows in Multistage Turbomachinery," ASME Paper 85-GT-220, 1985. Adamczyk, J. J., Mulac, R. A., and Celestina , M. L., "A Model for Closing the

  6. Detection of pump degradation

    Energy Technology Data Exchange (ETDEWEB)

    Casada, D. [Oak Ridge National Lab., TN (United States)

    1995-04-01

    There are a variety of stressors that can affect the operation of centrifugal pumps. Although these general stressors are active in essentially all centrifugal pumps, the stressor level and the extent of wear and degradation can vary greatly. Parameters that affect the extent of stressor activity are manifold. In order to assure the long-term operational readiness of a pump, it is important to both understand the nature and magnitude of the specific degradation mechanisms and to monitor the performance of the pump. The most commonly applied method of monitoring the condition of not only pumps, but rotating machinery in general, is vibration analysis. Periodic or continuous special vibration analysis is a cornerstone of most pump monitoring programs. In the nuclear industry, non-spectral vibration monitoring of safety-related pumps is performed in accordance with the ASME code. Pump head and flow rate are also monitored, per code requirements. Although vibration analysis has dominated the condition monitoring field for many years, there are other measures that have been historically used to help understand pump condition; advances in historically applied technologies and developing technologies offer improved monitoring capabilities. The capabilities of several technologies (including vibration analysis, dynamic pressure analysis, and motor power analysis) to detect the presence and magnitude of both stressors and resultant degradation are discussed.

  7. Study and Development of an Air Conditioning System Operating on a Magnetic Heat Pump Cycle

    Science.gov (United States)

    Wang, Pao-Lien

    1991-01-01

    This report describes the design of a laboratory scale demonstration prototype of an air conditioning system operating on a magnetic heat pump cycle. Design parameters were selected through studies performed by a Kennedy Space Center (KSC) System Simulation Computer Model. The heat pump consists of a rotor turning through four magnetic fields that are created by permanent magnets. Gadolinium was selected as the working material for this demonstration prototype. The rotor was designed to be constructed of flat parallel disks of gadolinium with very little space in between. The rotor rotates in an aluminum housing. The laboratory scale demonstration prototype is designed to provide a theoretical Carnot Cycle efficiency of 62 percent and a Coefficient of Performance of 16.55.

  8. Effects of Large Dam Removal and Groundwater Pumping on Stream Temperature under Humid, Semiarid, and Arid Conditions

    Science.gov (United States)

    Risley, J. C.; Constantz, J. E.; Essaid, H.; Rounds, S. A.

    2010-12-01

    The effects of large upstream dam removal and in-reach groundwater pumping on streamflows and stream temperature was analyzed for humid, semiarid, and arid conditions with long dry seasons representing typical climate conditions where large dams are present, such as the western US or eastern Australia. A MODFLOW-2000 model, with options for stream-aquifer interaction and grid-block rewetting, was constructed to simulate monthly streamflows for 12 watershed scenarios described below. For each scenario, streamflow output became input into a stream temperature simulation model. Stream temperatures were simulated using the CE-QUAL-W2 water quality model over a 110 km model grid, with the presence and removal of a dam at the top of the reach and pumping in the lower 60 km of the reach. Measured meteorological data from three locations in Oregon and California representing the three meterologic conditions were used as model input to simulate the impact of varying climate conditions on streamflows and stream temperature. For each climate condition, four hypothetical watershed scenarios were modeled: (1) natural (no dam or pumping), (2) large upstream dam present, (3) dam with in-reach pumping, and (4) no dam with pumping continued, resulting in 12 cases. Dam removal, in the presence or absence of pumping, created significant changes in streamflow characteristics, resulting in significant changes in stream temperature throughout the year for all three climate conditions. From March to August, the presence of a dam caused monthly mean stream temperatures to decrease on average by approximately 3.0°C, 2.5°C, and 2.0°C for the humid, semiarid, and arid conditions, respectively; however, stream temperatures generally increased from September to February. Pumping caused stream temperatures to warm in summer and cool in winter by generally less than 0.5°C. Though dam removal led to greater changes in stream temperature than pumping, ephemeral conditions were increased both

  9. Direct detection of red blood cell fragments: a new flow cytometric method to evaluate hemolysis in blood pumps.

    Science.gov (United States)

    Linneweber, J; Chow, T W; Takano, T; Maeda, T; Nonaka, K; Schulte-Eistrup, S; Kawahito, S; Elert, O; Moake, J L; Nosé, Y

    2001-01-01

    Pump induced hemolysis is presently evaluated by measuring plasma free hemoglobin (fHb). However, this method has disadvantages because quantification of fHb depends on hematocrit (HCT) and hemoglobin (Hb) levels. The aim of this work was to devise a hemoglobin independent method, capable of quantifying cell trauma directly by measuring the number of red blood cell (RBC) fragments. Whole blood flow cytometry was used to quantify circulating RBC fragments derived from a roller pump (Sarns, Inc. Model 2 M 6,002) and a centrifugal pump (Gyro C1E3, Kyocera Corp.). The pumps were tested in a mock circuit for 2 hr (5 L/min flow against 100 mm Hg pressure head). Red blood cell fragments were quantified by a phycoerythrin (PE) labeled glycophorin A antibody specific for erythrocytes. Red blood cell fragments were smaller than the intact RBC population and overlapped in size with the platelet population (based on forward- and side-light scattering measurements). For the roller pump, the values for RBC fragments increased from 1,090 +/- 260/microl at 0 min to 14,880 +/- 5,900/microl after 120 min. In contrast, using the centrifugal pump, there was little increase in RBC fragments (from 730 +/- 270/microl at 0 min to 1,400 +/- 840/microl after 120 min). Flow cytometry can be used for the rapid, sensitive, hemoglobin independent evaluation of pump induced RBC trauma.

  10. Numerical Simulation of Cavitation in a Centrifugal Pump at Low Flow Rate

    Institute of Scientific and Technical Information of China (English)

    TAN Lei; CAO Shu-Liang; WANG Yu-Ming; ZHU Bao-Shan

    2012-01-01

    Based on the full cavitation model which adopts homogeneous flow supposition and considering the compressibility effect on cavitation flow to modify the re-normalization group k-e turbulence model by the density function,a computational model is developed to simulate cavitation flow of a centrifugal pump at low flow rate.The NavierStokes equation is solved with the SIMPLEC algorithm.The calculated curves of net positive suction head available (NPSHa) HNPSHa agree well with the experimental data.The critical point of cavitation in centrifugal pump can be predicted precisely,and the NPSH critical values derived from simulation are consistent with the experimental data.Thus the veracity and reliability of this computational model are verified.Based on the result of numerical simulation,the distribution of vapor volume fraction in the impeller and pressure at the impeller inlet are analyzed.Cavities first appear on the suction side of the blade head near the front shroud.A large number of cavities block the impeller channels,which leads to the sudden drop of head at the cavitation critical point.With the reduction of NPSHa,the distribution of pressure at the impeller inlet is more uniform.%Based on the full cavitation model which adopts homogeneous Sow supposition and considering the compressibility effect on cavitation Row to modify the re-normalization group κ-ε turbulence model by the density function, a computational model is developed to simulate cavitation Bow of a centrifugal pump at low Bow rate. The Navier-Stokes equation is solved with the SIMPLEC algorithm. The calculated curves of net positive suction head available (NPSHa) Hnpshs agree well with the experimental data. The critical point of cavitation in centrifugal pump can be predicted precisely, and the NPSH critical values derived from simulation are consistent with the experimental data. Thus the veracity and reliability of this computational model are veriBed. Based on the result of numerical

  11. Global design optimization for an axial-flow tandem pump based on surrogate method

    Science.gov (United States)

    Li, D. H.; Zhao, Y.; Y Wang, G.

    2013-12-01

    Tandem pump, compared with multistage pump, goes without guide vanes between impellers. Better cavitation performance and significant reduction of the axial geometry scale is important for high-speed propulsion. This study presents a global design optimization method based on surrogated method for an axial-flow tandem pump to enhance trade-off performances: energy and cavitation performances. At the same time, interactions between impellers and impacts on the performances are analyzed. Fixed angle of blades in impellers and phase angle are performed as design variables. Efficiency and minimum average pressure coefficient (MAPC) on axial sectional surface in front impeller are the objective function, which can represent energy and cavitation performances well. Different surrogate models are constructed, and Global Sensitivity Analysis and Pareto Front method are used. The results show that, 1) Influence from phase angle on performances can be neglected compared with other two design variables, 2) Impact ratio of fixed angle of blades in two impellers on efficiency are the same as their designed loading distributions, which is 4:6, 3) The optimization results can enhance the trade-off performances well: efficiency is improved by 0.6%, and the MAPC is improved by 4.5%.

  12. Flux Vector Splitting Schemes for Water Hammer Flows in Pumping Supply Systems with Air Vessels

    Institute of Scientific and Technical Information of China (English)

    Qiang Sun; Yuebin Wu; Ying Xu; Tae Uk Jang

    2015-01-01

    To solve water hammer problems in pipeline systems, many numerical simulation approaches have been developed. This paper improves a flux vector splitting ( FVS) scheme whose grid is the same as the fixed⁃grid MOC scheme. The proposed FVS scheme is used to analyze water hammer problems caused by a pump abrupt shutdown in a pumping system with an air vessel. This paper also proposes a pump⁃valve⁃vessel model combining a pump⁃valve model with an air vessel model. The results show that the data obtained by the FVS scheme are similar to the ones obtained by the fixed⁃grid method of characteristics ( MOC ) . And the results using the pump⁃valve⁃vessel model are almost the same as the ones using both the pump⁃valve model and the air vessel model. Therefore, it is effective that the proposed FVS scheme is used to solve water hammer problems and the pump⁃valve⁃vessel model replaces both the pump⁃valve model and the air vessel model to simulate water hammer flows in the pumping system with the air vessel.

  13. Computational Study of the Noise Radiation in a Centrifugal Pump When Flow Rate Changes

    Directory of Open Access Journals (Sweden)

    Ming Gao

    2017-02-01

    Full Text Available Noise radiation is of importance for the performance of centrifugal pumps. Aiming at exploring noise radiation patterns of a typical centrifugal pump at different flow rates, a three-dimensional unsteady hydro/aero acoustic model with large eddy simulation (LES closure is developed. Specifically, the Ffowcs Williams-Hawkings model (FW-H is employed to predict noise generation by the impeller and volute. The simulated flow fields reveal that the interactions of the blades with the volute induce root mean square (RMS pressure and further lead to noise radiation. Moreover, it is found that the profiles of total sound pressure level (TSPL regarding the directivity field for the impeller-generated noise demonstrate a typical dipole characteristic behavior, whereas strictly the volute-generated noise exhibits an apparently asymmetric behavior. Additionally, the design operation (Here, 1 Q represents the design operation generates the lowest TSPL vis-a-vis the off-design operations for all the flow rates studied. In general, as the flow rates decrease from 1 Q to 0.25 Q, TSPL initially increases significantly before 0.75 Q and then levels off afterwards. A similar trend appears for cases having the larger flow rates (1–1.25 Q. The TSPL deviates with the radiation directivity and the maximum is about 50%. It is also found that TSPL by the volute and the blades can reach ~87 dB and ~70 dB at most, respectively. The study may offer a priori guidance for the experimental set up and the actual design layout.

  14. Centrifugal pumps

    CERN Document Server

    Gülich, Johann Friedrich

    2014-01-01

    This book gives an unparalleled, up-to-date, in-depth treatment of all kinds of flow phenomena encountered in centrifugal pumps including the complex interactions of fluid flow with vibrations and wear of materials. The scope includes all aspects of hydraulic design, 3D-flow phenomena and partload operation, cavitation, numerical flow calculations, hydraulic forces, pressure pulsations, noise, pump vibrations (notably bearing housing vibration diagnostics and remedies), pipe vibrations, pump characteristics and pump operation, design of intake structures, the effects of highly viscous flows, pumping of gas-liquid mixtures, hydraulic transport of solids, fatigue damage to impellers or diffusers, material selection under the aspects of fatigue, corrosion, erosion-corrosion or hydro-abrasive wear, pump selection, and hydraulic quality criteria. As a novelty, the 3rd ed. brings a fully analytical design method for radial impellers, which eliminates the arbitrary choices inherent to former design procedures. The d...

  15. Development of a Mechatronic Syringe Pump to Control Fluid Flow in a Microfluidic Device Based on Polyimide Film

    Science.gov (United States)

    Sek Tee, Kian; Sharil Saripan, Muhammad; Yap, Hiung Yin; Fhong Soon, Chin

    2017-08-01

    With the advancement in microfluidic technology, fluid flow control for syringe pump is always essential. In this paper, a mechatronic syringe pump will be developed and customized to control the fluid flow in a poly-dimethylsiloxane (PDMS) microfluidic device based on a polyimide laminating film. The syringe pump is designed to drive fluid with flow rates of 100 and 1000 μl/min which intended to drive continuous fluid in a polyimide based microfluidic device. The electronic system consists of an Arduino microcontroller board and a uni-polar stepper motor. In the system, the uni-polar stepper motor was coupled to a linear slider attached to the plunger of a syringe pump. As the motor rotates, the plunger pumps the liquid out of the syringe. The accuracy of the fluid flow rate was determined by adjusting the number of micro-step/revolution to drive the stepper motor to infuse fluid into the microfluidic device. With the precise control of the electronic system, the syringe pump could accurately inject fluid volume at 100 and 1000 μl/min into a microfluidic device.

  16. Numerical simulation of seepage flow field in groundwater source heat pump system and its influence on temperature field

    Institute of Scientific and Technical Information of China (English)

    Jihua HU; Yanjun ZHANG; Danyan DU; Gang WU; Ziwang YU; Chen WANG; Fuquan NI

    2008-01-01

    Energy utilization in the aquifers is a new technology closely related to development of heat pump technique. It is significant for the flow distribution to be predicted in the aquifer surrounding the Groundwater Source Heat Pump System (GSHPS). The authors presented a new concept of "flow transfixion" by analyzing general features of aquifers, and then discussed interaction of the flow transfixion with the heat transfixion, which has practical significance to projects. A numerical model of groundwater flow was established based on the basic tenets of water-heat transferring in the aquifer. On this basis the flow field and the temperature field of GSHPS for a site in Shenyang City were numerically simulated. The basis of the flow transfixion was obtained; it was discussed for the influence of the flow transfixion on the heat transfixion. To a certain extent, the study offers some reference for the projects' design of GSHP in the studied area.

  17. Effects of the pulsatile flow settings on pulsatile waveforms and hemodynamic energy in a PediVAS centrifugal pump.

    Science.gov (United States)

    Wang, Shigang; Rider, Alan R; Kunselman, Allen R; Richardson, J Scott; Dasse, Kurt A; Undar, Akif

    2009-01-01

    The objective of this study was to test different pulsatile flow settings of the PediVAS centrifugal pump to seek an optimum setting for pulsatile flow to achieve better pulsatile energy and minimal backflow. The PediVAS centrifugal pump and the conventional pediatric clinical circuit, including a pediatric membrane oxygenator, arterial filter, arterial cannula, and 1/4 in circuit tubing were used. The circuit was primed with 40% glycerin water mixture. Postcannula pressure was maintained at 40 mm Hg by a Hoffman clamp. The experiment was conducted at 800 ml/min of pump flow with a modified pulsatile flow setting at room temperature. Pump flow and pressure readings at preoxygenator and precannula sites were simultaneously recorded by a data acquisition system. The results showed that backflows appeared at flow rates of 200-800 ml/min (200 ml/min increments) with the default pulsatile flow setting and only at 200 ml/min with the modified pulsatile flow setting. With an increased rotational speed difference ratio and a decreased pulsatile width, the pulsatility increased in terms of surplus hemodynamic energy and total hemodynamic energy at preoxygenator and precannula sites. Backflows seemed at preoxygenator and precannula sites at a 70% of rotational speed difference ratio. The modified pulsatile flow setting was better than the default pulsatile flow setting in respect to pulsatile energy and backflow. The pulsatile width and the rotational speed difference ratio significantly affected pulsatility. The parameter of the rotational speed difference ratio can automatically increase pulsatility with increased rotational speeds. Further studies will be conducted to optimize the pulsatile flow setting of the centrifugal pump.

  18. A NUMERICAL SIMULATION OF 3-D INNER FLOW IN UP-STREAM PUMPING MECHANICAL SEAL

    Institute of Scientific and Technical Information of China (English)

    ZHANG Jin-feng; YUAN Shou-qi; FU Yong-hong; FANG Yu-jian

    2006-01-01

    Numerical simulation of 3-D inner flow between Up-stream Pumping Mechanical Face Seals (UPMFS) faces was initially done by CFD software, which made the flow visualization come true.Simulation results directly discover the action of hydrodynamic lubrication, and by comparison with that of Conventional Mechanic Face Seals (CMFS), the advantage over bigger bearing capability, less friction and much less leakage are explained clearly.Otherwise there are also some different ideas and results from precedent analysis and computational research results: dynamic and static pressure profiles can be obtained respectively instead of the analytic total pressure distribution only, pressure distribution is nonlinear, while always be solved as linear, lower pressure is observed at the area of inner diameter caused by the grooves, but its possible cavitations effects to the performance of UPMFS still need further study.

  19. Carbon-ammonia pairs for adsorption refrigeration applications: ice making, air conditioning and heat pumping

    Energy Technology Data Exchange (ETDEWEB)

    Tamainot-Telto, Z.; Metcalf, S.J.; Critoph, R.E.; Zhong, Y.; Thorpe, R. [School of Engineering, University of Warwick, Gibbet Hall Road, Coventry CV4 7AL (United Kingdom)

    2009-09-15

    A thermodynamic cycle model is used to select an optimum adsorbent-refrigerant pair in respect of a chosen figure of merit that could be the cooling production (MJ m{sup -3}), the heating production (MJ m{sup -3}) or the coefficient of performance (COP). This model is based mainly on the adsorption equilibrium equations of the adsorbent-refrigerant pair and heat flows. The simulation results of 26 various activated carbon-ammonia pairs for three cycles (single bed, two-bed and infinite number of beds) are presented at typical conditions for ice making, air conditioning and heat pumping applications. The driving temperature varies from 80 C to 200 C. The carbon absorbents investigated are mainly coconut shell and coal based types in multiple forms: monolithic, granular, compacted granular, fibre, compacted fibre, cloth, compacted cloth and powder. Considering a two-bed cycle, the best thermal performances based on power density are obtained with the monolithic carbon KOH-AC, with a driving temperature of 100 C; the cooling production is about 66 MJ m{sup -3} (COP = 0.45) and 151 MJ m{sup -3} (COP = 0.61) for ice making and air conditioning respectively; the heating production is about 236 MJ m{sup -3} (COP = 1.50). (author) [French] Un modele du cycle thermodynamique est utilise pour selectionner le meilleur couple adsorbant-ammoniac sur la base de la production frigorifique (MJ m{sup -3}), la production de chaleur (MJ m{sup -3}) ou bien le coefficient de performance (COP). Ce modele est essentiellement base sur les equations d'etat de l'adsorption (adsorbant-ammoniac). Les resultats de simulation de 26 differents couples charbon actif-ammoniac sont presentes pour des conditions typiques de fabrication de la glace, de climatisation et de pompe a chaleur. La temperature de generation varie de 80 C a 200 C. Les simulations sont effectuees pour trois types de cycle: lit unique, deux-lits et un nombre infini de lits. Les charbons actifs etudies sont

  20. Limiting pumping from the Edwards Aquifer: An economic investigation of proposals, water markets, and spring flow guarantees

    Science.gov (United States)

    McCarl, Bruce A.; Dillon, Carl R.; Keplinger, Keith O.; Williams, R. Lynn

    1999-04-01

    The Edwards Aquifer, near San Antonio, Texas, is an important water source for both pumping and spring flow, which in turn provides water for recreation and habitat for several endangered species. A management authority is charged with aquifer management and is mandated to reduce pumping, facilitate water markets, protect agricultural rights, and protect the species habitat. This paper examines the economic dimensions of authority duties. A combined hydrologic-economic model is used in the investigation. The results indicate that proposed pumping limits are shown to have large consequences for agricultural usage and to decrease the welfare of current aquifer pumping users. However, the spring flow habitat is found to be protected, and the gains from that protection would have to exceed pumping user losses in order for the protection measures to increase regional economic welfare. Agricultural guarantees are shown to cause use value differences, indicating the opportunity for emergence of an active water market. Fixed quantity pumping limits are found to be an expensive way of insuring adequate spring flow.

  1. Simulating of single phase flow in typical centrifugal pumps oil industry; Simulacao do escoamento monofasico em bombas centrifugas tipicas da industria do petroleo

    Energy Technology Data Exchange (ETDEWEB)

    Andrade, Ana Carla Costa; Silva, Aldrey Luis Morais da; Maitelli, Carla Wilza Souza de Paula [Universidade Federal do Rio Grande do Norte (UFRN), RN (Brazil)

    2012-07-01

    With the various techniques applied in production processes and oil exploration, has been using the artificial lift equipment with the aim of promoting an increase in flow in oil wells and gas. Choosing the most appropriate method of elevation depends on certain factors, among them the initial costs of installation, maintenance and conditions in the producing field, resulting in a more precise analysis of the project. Although there are other methods that represent a low cost and easy maintenance, the BCS method (Electrical Submersible Pumping), appears to be quite effective when it is intended to pump more flow of liquids from both terrestrial and marine environments, in conditions adverse temperature, presence of free gas in the mixture and viscous fluids. This method is based in most cases where the vessel pressure was low, and the fluid does not reach the surface without intervention of an artificial means which can lift them. Similar happens at the end of productive life of a resurgence for the well, or even when the flow of it is far below what is expected to produce, requiring a complement of natural energy through artificial lift. By definition, the BCS is a method of artificial lift in which a subsurface electric motor turns electrical energy into mechanical centrifugal pump and a multistage overlapping converts mechanical energy into kinetic energy of the engine bringing the fluid surface. In this study we performed computer simulations using a commercial program ANSYS #Registered Sign# CFX #Registered Sign# dimensions previously obtained by the 3D geometry in CAD format, with the objective of evaluating the single-phase flow inside typical centrifugal pump submerged in the oil industry. The variable measured was the height of elevation and drilling fluids are oil and water.(author)

  2. Modeling radial flow ion exchange performance for condensate polisher conditions

    Energy Technology Data Exchange (ETDEWEB)

    Shallcross, D. [University of Melbourne, Melbourne, VIC (Australia). Department of Chemical Engineering; Renouf, P.

    2001-11-01

    A theoretical model is developed which simulates ion exchange performance within an annular resin bed. Flow within the mixed ion exchange bed is diverging, with the solution flowing outwards away from the bed's axis. The model is used to simulate performance of a mixed annular bed operating under condensate polisher conditions. The simulation predictions are used to develop design envelope curves for practical radial flow beds and to estimate potential cost savings flowing from less expensive polisher vessels. (orig.)

  3. An in vivo model of in situ implantation using pulmonary valved conduit in large animals under off-pump condition

    Institute of Scientific and Technical Information of China (English)

    WU Hao; XU Zhi-wei; LIU Xian-min; GONG Da; WAN Ju-yi; XU Xiu-fang; ZHOU Zi-fan

    2013-01-01

    Background The application of pulmonary valved conduit to reconstruct the continuity between right ventricles and pulmonary artery is one of the major surgeries.This study aimed to establish an in vivo model of in situ implantation using pulmonary valved conduit in large animals under off-pump condition to validate the long-term effects of artificial pulmonary valved conduit.Methods Domesticate juvenile male sheep and tissue-engineered poorine pulmonary valved conduit were used for the experiment:30 sheep,weighing (15±3) kg (range 13 to 17 kg) were randomly divided into two groups which were all operated under general anesthesia by off-pump surgery (group 1) and left thoracotomy (group 2).Two different off-pump surgical methods were used to perform cannulation in sheep pulmonary artery to replace part of sheep pulmonary artery with pulmonary valved conduit which will work together with sheep pulmonary artery and valves.During the experiments,animal survival,complication rates,operating time and blood loss were recorded to compare the results between groups and to establish a surgical method with minimal invasion,simplicity,safety,and high success rates.Results In group 1,a total of 15 cases of surgeries were performed,in which two sheep died; the operative mortality was 13.3% (2/15).In group 2,a total of 15 cases of surgeries were performed,and the surgical mortality rate was 0 (0/15).The operation time and blood loss in group 2 was significantly better than that in group 1.The postoperative echocardiograms showed that,after the surgeries by these two methods,the blood flows were normal,and the valves can open and close freely.Autopsy after 6 months showed that the inner wall and the valves of pulmonary valved conduit were smooth with no thrombus formation.Conclusion These two off-pump methods are feasible and safe with fewer traumas; but the second method is better and particularly suitable for the establishment of a juvenile animal model.

  4. Initial hydrodynamic study on a new intraaortic axial flow pump: Dynamic aortic valve

    Institute of Scientific and Technical Information of China (English)

    LI; Guorong

    2001-01-01

    pump: the valvo-pump, in Heart Replacement: Artificial Heart (eds. Akutsu, T., Koyanagi, H.), 4, Tokyo: Springer-Verlag, 1993, 267-272.[13] Mitamura,Y., Nakamura,H., Okamoto,E.et al., Development of the valvo-pump:an axial flow pump implanted at the heart valve position,Artif.Organs,1999,23:566/

  5. Stream Temperature Spatial and Temporal Response to Large Dam Removal and Groundwater Pumping under Varying Climate Conditions

    Science.gov (United States)

    Risley, J. C.; Constantz, J. E.; Essaid, H.; Rounds, S. A.

    2016-12-01

    We simulated the effects of large upstream dam removal and in-reach groundwater pumping on stream temperature spatial and temporal patterns in a hypothetical river basin under varying climate conditions. A MODFLOW-2000 model, with options for stream-aquifer interaction and grid-block rewetting, was constructed to simulate monthly streamflows for 12 watershed scenarios described below. For each scenario, streamflow output became input into a stream temperature simulation model. Stream temperatures were simulated using the CE-QUAL-W2 water quality model over a 110 km model grid, with the presence and removal of a dam at the top of the reach and pumping in the lower 60 km of the reach. Measured meteorological data from three locations in Oregon and California representing the three meteorological conditions were used as model input to simulate the impact of varying climate conditions on streamflows and stream temperature. For each climate condition, four hypothetical watershed scenarios were modeled: (1) natural (no dam or pumping), (2) large upstream dam present, (3) dam with in-reach pumping, and (4) no dam with pumping continued, resulting in 12 cases. If a transition from a humid to more arid environment occurs under future climate change, the simulations showed that decreased streamflow, increased solar radiation, and increased air temperatures would result in overall increased stream temperatures as expected. From March to August, the presence of a dam caused monthly mean stream temperatures to decrease on average by approximately 3.0°C, 2.5°C, and 2.0°C for the humid, semiarid, and arid conditions, respectively; however, stream temperatures generally increased from September to February. Pumping caused stream temperatures to warm in summer and cool in winter by generally less than 0.5°C. Though dam removal led to greater changes in stream temperature than pumping, ephemeral conditions were increased both temporally and spatially by pumping.

  6. Transient two-phase performance of LOFT reactor coolant pumps

    Energy Technology Data Exchange (ETDEWEB)

    Chen, T.H.; Modro, S.M.

    1983-01-01

    Performance characteristics of Loss-of-Fluid Test (LOFT) reactor coolant pumps under transient two-phase flow conditions were obtained based on the analysis of two large and small break loss-of-coolant experiments conducted at the LOFT facility. Emphasis is placed on the evaluation of the transient two-phase flow effects on the LOFT reactor coolant pump performance during the first quadrant operation. The measured pump characteristics are presented as functions of pump void fraction which was determined based on the measured density. The calculated pump characteristics such as pump head, torque (or hydraulic torque), and efficiency are also determined as functions of pump void fractions. The importance of accurate modeling of the reactor coolant pump performance under two-phase conditions is addressed. The analytical pump model, currently used in most reactor analysis codes to predict transient two-phase pump behavior, is assessed.

  7. Experimental Study on Series Operation of Sliding Vane Pump and Centrifugal Pump

    Directory of Open Access Journals (Sweden)

    Tao Li

    2013-01-01

    Full Text Available A platform for sliding vane pump and centrifugal pump tests is installed to study the series operation of them under different characteristics of pipeline. Firstly, the sliding vane pump and the centrifugal pump work independently, and the performance is recorded. Then, the two types of pumps are combined together, with the sliding vane pump acting as the feeding pump. Comparison is made between the performance of the independently working pump and the performance of series operation pump. Results show that the system flow rate is determined by the sliding vane pump. In order to ensure the stability of the series operation pumping system, the energy consumption required by the pipeline under the system flow should be greater than the pressure energy centrifugal pump can generate. Otherwise, the centrifugal pump can not operate stably, with reflux, swirl, gas-liquid two-phase flow in the runner and strong vibration and noise. The sliding vane pump can be in serial operation with the centrifugal pump under limited conditions.

  8. Numerical modelling of groundwater flow to understand the impacts of pumping on arsenic migration in the aquifer of North Bengal Plain

    Science.gov (United States)

    Sikdar, P. K.; Chakraborty, Surajit

    2017-03-01

    In this paper, numerical simulations of regional-scale groundwater flow of North Bengal Plain have been carried out with special emphasis on the arsenic (As)-rich alluvium filled gap between the Rajmahal hills on the west and the Garo hills on the east. The proposed concern of this modelling arose from development that has led to large water table declines in the urban area of English Bazar block, Malda district, West Bengal and possible transport of As in the near future from the adjacent As-polluted aquifer. Groundwater occurs under unconfined condition in a thick zone of saturation within the Quaternary alluvial sediments. Modelling indicates that current pumping has significantly changed the groundwater flowpaths from pre-development condition. At the present pumping rate, the pumping wells of the urban area may remain uncontaminated till the next 25 yrs, considering only pure advection of water but some water from the As-polluted zone may enter wells by 50 yrs. But geochemical and other processes such as adsorption, precipitation, redox reaction and microbial activity may significantly retard the predicted rate by advective transport. In the rural areas, majority of the water pumped from the aquifer is for irrigation, which is continuously re-applied on the surface. The near-vertical nature of the flowpaths indicates that, where As is present or released at shallow depths, it will continue to occur in pumping wells. Modelling also indicates that placing all the pumping wells at depths below 100 m may not provide As-free water permanently.

  9. Numerical modelling of groundwater flow to understand the impacts of pumping on arsenic migration in the aquifer of North Bengal Plain

    Indian Academy of Sciences (India)

    P K Sikdar; Surajit Chakraborty

    2017-03-01

    In this paper, numerical simulations of regional-scale groundwater flow of North Bengal Plain have been carried out with special emphasis on the arsenic (As)-rich alluvium filled gap between the Rajmahal hills on the west and the Garo hills on the east. The proposed concern of this modelling arose from development that has led to large water table declines in the urban area of English Bazar block, Malda district, West Bengal and possible transport of As in the near future from the adjacent As-polluted aquifer. Groundwater occurs under unconfined condition in a thick zone of saturation within the Quaternaryalluvial sediments. Modelling indicates that current pumping has significantly changed the groundwater flowpaths from pre-development condition. At the present pumping rate, the pumping wells of the urban area may remain uncontaminated till the next 25 yrs, considering only pure advection of water but some water from the As-polluted zone may enter wells by 50 yrs. But geochemical and other processes such as adsorption, precipitation, redox reaction and microbial activity may significantly retard the predicted rate by advective transport. In the rural areas, majority of the water pumped from the aquifer is forirrigation, which is continuously re-applied on the surface. The near-vertical nature of the flowpaths indicates that, where As is present or released at shallow depths, it will continue to occur in pumping wells. Modelling also indicates that placing all the pumping wells at depths below 100 m may not provideAs-free water permanently.

  10. Research and Development on Heat Pumps for Space Conditioning Applications: Proceedings of the DOE/ORNL Heat Pump Conference

    Science.gov (United States)

    Jacobs, V. A.; Powell, R. H., Jr.

    1985-08-01

    This conference was planned to provide information on current activities in the US Department of Energy (DOE) and Oak Ridge National Laboratory (ORNL) Building Equipment Research (BER) Program. It was primarily for the benefit of HVAC equipment manufacturers and other interested parties, including utilities, independent research and development organizations, universities, other government groups, and research funding and management organizations. The technical presentations were grouped into two principal subject areas: electric systems and thermally activated systems. Electric-system topics included field performance studies, laboratory experiments on cycling performance, analytical estimates of the benefits of variable capacity and zone control, nonazeotropic refrigerant mixtures, ground-coupled systems, and an analysis of Stirling-cycle heat pumps. In the area of thermally activated heat pumps, presentations centered on the development of absorption systems, Stirling-engine-driven systems, and a linear, free-piston IC-engine compressor. Separate abstracts have been prepared for 27 presentations for inclusion in the Energy Data Base.

  11. Comparative study of graft flow between on-pump and off-pump coronary bypass surgery for patients with multivessel coronary artery disease

    Institute of Scientific and Technical Information of China (English)

    Xin Chen; Ming Xu; Zhibing Qiu; Yinshuo Jiang; Liming Wang; Liqiong Xiao

    2006-01-01

    Objective: To Comparatively study grafts flow between on-pump and off-pump coronary bypass surgery for patients with triple coronary artery disease. Methods: The grafts flow was studied in 100 patients of OPCAB and compared with100 cases of CCABG by means of Medi-Stim Butterfly Flowmeter measurement intraoperatively. Results: The mean number of the distal anastomosis was 3.78+ 1.11 in CCABG group, and 3.83 + 0.93 in OPCAB group. The index of completeness of revascularization in CCABG group was 1.01 + 0.08, and 1.10+ 0.09 in OPCAB group. The flow of grafts was satisfied in all patients. The PI values were all under 5. There was no significant difference in the mean graft flow and PI value between two groups.Conclusion: OPCAB can provide the same grafts flow and similar completeness of revascularization when compared with CCABG which indicates the similar anastomosis quality of grafts in OPCAB and CCABG groups.

  12. Blood warming, pump heating and haemolysis in low-flow extracorporeal life support; an in vitro study using freshly donated human blood.

    Science.gov (United States)

    Kusters, R W J; Simons, A P; Lancé, M D; Ganushchak, Y M; Bekers, O; Weerwind, P W

    2017-01-01

    Low-flow extracorporeal life support can be used for cardiopulmonary support of paediatric and neonatal patients and is also emerging as a therapy for patients suffering from exacerbation of chronic obstructive pulmonary disease. However, pump heating and haemolysis have proven to negatively affect the system and outcome. This in vitro study aimed at gaining insight into blood warming, pump heating and haemolysis related to the performance of a new low-flow centrifugal pump. Pump performance in the 400-1,500 ml/min flow range was modulated using small-sized dual-lumen catheters and freshly donated human blood. Measurements included plasma free haemoglobin, blood temperature, pump speed, pump pressure, blood flow and thermographic imaging. Blood warming (ΔTmax=0.5°C) had no relationship with pump performance or haemolysis (R(2)max=0.05). Pump performance-related parameters revealed no relevant relationships with haemolysis (R(2)max=0.36). Thermography showed no relevant heat zones in the pump (Tmax=36°C). Concerning blood warming, pump heating and haemolysis, we deem the centrifugal pump applicable for low-flow extracorporeal circulation.

  13. Free surface flows under compensated gravity conditions

    CERN Document Server

    Dreyer, Miachel E

    2007-01-01

    This book considers the behavior of fluids in a low-gravity environment with special emphasis on application in PMD (propellant management device) systems . In the compensated gravity environment of a spacecraft, the hydrostatic pressure decreases to very low values depending on the residual acceleration, and surface tension forces become dominant. Consequently, surface tension can be used to transport and position liquids if the residual acceleration and the resulting hydrostatic pressure are small compared to the capillary pressure. One prominent application is the use of PMDs in surface-tension satellite tanks. PMDs must ensure that the tank outlet is covered with liquid whenever outflow is demanded. Furthermore, PMDs are used to ensure expulsion and refilling of tanks for liquids and gases for life support, reactants, and experiment supplies. Since most of the PMD designs are not testable on ground and thus rely on analytical or numerical concepts, this book treats three different flow problems with analy...

  14. Effects of Boundary Conditions on Single-File Pedestrian Flow

    CERN Document Server

    Zhang, Jun; Seyfried, Armin

    2015-01-01

    In this paper we investigate effects of boundary conditions on one dimensional pedestrian flow which involves purely longitudinal interactions. Qualitatively, stop-and-go waves are observed under closed boundary condition and dissolve when the boundary is open. To get more detailed information the fundamental diagrams of the open and closed systems are compared using Voronoi-based measurement method. Higher maximal specific flow is observed from the pedestrian movement at open boundary condition.

  15. Non-invasive estimation of pulsatile flow and differential pressure in an implantable rotary blood pump for heart failure patients.

    Science.gov (United States)

    AlOmari, A H; Savkin, A V; Karantonis, D M; Lim, E; Lovell, N H

    2009-04-01

    We propose dynamical models for pulsatile flow and head estimation in an implantable rotary blood pump. Pulsatile flow and head data were obtained using a circulatory mock loop where fluid solutions with different values of viscosities were used as a blood analogue with varying haematocrit (HCT). Noninvasive measurements of power and pump speed were used with HCT values as inputs to the flow model while the estimated flow was used with the speed as inputs to a head estimation model. Linear regression analysis between estimated and measured flows obtained from a mock loop resulted in a highly significant correlation (R2=0.982) and a mean absolute error (e) of 0.323 L min(-1), while for head, R2=0.933 and e=7.682 mmHg were obtained. R2=0.849 and e=0.584 L min(-1) were obtained when the same model derived in the mock loop was used for flow estimation in ex vivo porcine data (N=6). Furthermore, in the steady state, the solution of the presented flow model can be described by a previously designed and verified static model. The models developed herein will play a vital role in developing a robust control system of the pump flow coping with changing physiological demands.

  16. Photoplethysmography for an independent measure of pulsatile pressure under controlled flow conditions.

    Science.gov (United States)

    Njoum, Haneen; Kyriacou, Panayiotis A

    2017-02-01

    Noninvasive continuous blood pressure measurements are desirable for patients and clinicians. This work proposes and validates a method for transmural pressure measurement using photoplethysmography (PPG) in an in vitro setup that allows control of pressure and flow conditions. The optimum pulsatile volume measure is obtained by comparing parameters extracted from the photoplethysmographic signal (AC amplitude, normalized pulse volume (NPV) and adjusted pulse volume (APV)). Pulsatile volume can then provide pressure measurements using the exponential pressure-volume (P-V) relationship and validated using the gold standard catheter pressure measurement. Pressure, red (R) and infrared (IR) PPG signals were recorded continuously in two arterial models with different cross-sectional areas (Model 1 and Model 2) utilising a pulsatile pump. Flow rates were controlled by varying pumping frequencies at low and high stroke volumes. The optimum method for estimation of the pulsatile volume is through APV, which had a highly significant correlation (r (2)  =  0.99, p  blood pressure measurement at different flow conditions.

  17. Optimization of an axial flow heart pump with active and passive magnetic bearings.

    Science.gov (United States)

    Glauser, Matthias; Jiang, Wei; Li, Guoxin; Lin, Zongli; Allaire, Paul E; Olson, Don

    2006-05-01

    Optimization of a magnetically suspended left ventricular assist device (LVAD) is crucial. We desire a totally implantable, long-life LVAD that delivers the necessary flow rate, pressure rise, and blood compatibility. By using a novel combination of passive and active magnetic bearings (AMBs), we have developed an axial flow LVAD prototype, the LEV-VAD, which provides an unobstructed blood flow path, preventing stagnation regions for the blood. Our current effort is focused on the optimization of the magnetic suspension system to allow for control of the AMB, minimizing its size and power consumption. The properties of the passive magnetic bearings and AMBs serve as parameter space, over which a cost function is minimized, subject to constraints such as suspension stability and sufficient disturbance rejection capabilities. The design process is expected to lead to the construction of a small prototype pump along with the necessary robust controller for the AMB. Sensitivity of the LVAD performance with respect to various design parameters is examined in-depth and an optimized, more compact LVAD prototype is designed.

  18. A unified slip boundary condition for flow over a surface

    CERN Document Server

    Thalakkottor, Joseph John

    2015-01-01

    Interface between two phases of matter are ubiquitous in nature and technology. Determining the correct velocity condition at an interface is essential for understanding and designing of flows over a surface. We demonstrate that both the widely used no-slip and the Navier and Maxwell slip boundary conditions do not capture the complete physics associated with complex problems, such as spreading of liquids or corner flows. Hence, we present a unified boundary condition that is applicable to a wide-range of flow problems.

  19. Theoretical study of flow ripple for an aviation axial-piston pump with damping holes in the valve plate

    Institute of Scientific and Technical Information of China (English)

    Guan Changbin; Jiao Zongxia; He Shouzhan

    2014-01-01

    Based on the structure of a certain type of aviation axial-piston pump’s valve plate which adopts a pre-pressurization fluid path (consisting a damping hole, a buffer chamber, and an orifice) to reduce flow ripple, a single-piston model of the aviation axial-piston pump is presented. This sin-gle-piston model comprehensively considers fluid compressibility, orifice restriction effect, fluid resistance in the capillary tube, and the leakage flow. Besides, the instantaneous discharge areas used in the single-piston model have been calculated in detail. Based on the single-piston model, a multi-piston pump model has been established according to the simple hydraulic circuit. The sin-gle-and multi-piston pump models have been realized by the S-function in Matlab/Simulink. The developed multi-piston pump model has been validated by being compared with the numerical result by computational fluid dynamic (CFD). The effects of the pre-pressurization fluid path on the flow ripple and the instantaneous pressure in the piston chamber have been studied and opti-mized design recommendations for the aviation axial-piston pump have been given out.

  20. Pump Coupling & Motor bearing damage detection using Condition Monitoring at DTPS

    Science.gov (United States)

    Bari, H. M.; Deshpande, A. A.; Jalkote, P. S.; Patil, S. S.

    2012-05-01

    This paper shares a success story out of the implementation of Co-ordinated Condition Monitoring techniques at DTPS, wherein imminent Mis-alignment of HT auxiliary BFP - 1B and Motor bearing failure of ID FAN - 1B was diagnosed. On 30/12/2010, Booster Pump DE horizontal reading increased from 4.8 to 5.1 and then upto 5.9 mm/sec. It was suspected that Booster pump was mis-aligned with Motor. To confirm misalignment, Phase Analysis was also done which showed that Coupling phase difference was 180 Degrees. Vibration & Phase Analysis helped in diagnosing the exact root cause of abnormity in advance, saving plant from huge losses which could have caused total cost of £ 104,071. On 06/01/2011, ID fan 1B Motor NDE & DE horizontal vibration readings deviated from 0.5 to 0.8 and 0.6 to 0.8 mm/sec (RMS) respectively. Noise level increased from 99.1 to 101.9 db. It was suspected that Motor bearings had loosened over the shaft. Meanwhile, after opening of Motor, Inner race of NDE side was found cracked and loosened over the shaft. Vibration Analysis & Noise Monitoring helped in diagnosing the exact root cause of abnormity in advance, saving plant from huge losses which could have caused total cost of £ 308,857.

  1. Simple computer program to model 3-dimensional underground heat flow with realistic boundary conditions

    Science.gov (United States)

    Metz, P. D.

    A FORTRAN computer program called GROCS (GRound Coupled Systems) has been developed to study 3-dimensional underground heat flow. Features include the use of up to 30 finite elements or blocks of Earth which interact via finite difference heat flow equations and a subprogram which sets realistic time and depth dependent boundary conditions. No explicit consideration of mositure movement or freezing is given. GROCS has been used to model the thermal behavior of buried solar heat storage tanks (with and without insulation) and serpentine pipe fields for solar heat pump space conditioning systems. The program is available independently or in a form compatible with specially written TRNSYS component TYPE subroutines. The approach taken in the design of GROCS, the mathematics contained and the program architecture, are described. Then, the operation of the stand-alone version is explained. Finally, the validity of GROCS is discussed.

  2. The Uncertainty of Mass Discharge Measurements Using Pumping Methods Under Simplified Conditions

    Science.gov (United States)

    Mass discharge measurements at contaminated sites have been used to assist with site management decisions, and can be divided into two broad categories: point-scale measurement techniques and pumping methods. Pumping methods can be sub-divided based on the pumping procedures use...

  3. Improving the monitoring of quantitative conditions of peacetime fuel stocks at pumping stations

    Directory of Open Access Journals (Sweden)

    Slaviša M. Ilić

    2011-04-01

    human resources. Optimization of quantitative monitoring of peacetime supplies of fuel at gas stations should aim at reducing the impact of the human factor, introducing automated quantitative monitoring of fuel condition with modern equipment for handling as well as applying technology for fast reading and dissemination of information and reports. Civilian pumping stations have been modernized gradually with new digital pump machines, systems for automated production and automated systems for measuring the fuel level in buried tanks. The objectives and criteria of the optimization of model monitoring In order to solve the problem of multi-criteria nature, the methods of operational research have been applied and the formalization of problem solving has been carried out. Models have been identified, criteria and subcriteria have been defined as well as respective criteria values, sub-criteria and weight coefficients for chosen variants in order to rank the alternatives - models. On the basis of the defined objectives and optimization approaches, the task of optimization to be solved is to choose one optimal model of monitoring the quantitative condition of peacetime stocks of fuels at gas stations, out of three variations or alternative models. Application of expert assessment and methods of analytical hierarchy process The problem was solved first 'manually', by using MS Excell, and after that by using the Expert Choice software package. The Expert Choice software package is based on the application of the method of analytical hierarchy process and combines the benefits that this method offers with the speed and visibility of computerized calculations and their result display. The purpose of the AHP method is to rank alternative decisions by their importance and to select the most acceptable alternative on the basis of a defined set of criteria and alternatives. The problem of determining the weight of criteria has been determined by applying the method of expert

  4. Energy Performance and Radial Force of a Mixed-Flow Pump with Symmetrical and Unsymmetrical Tip Clearances

    Directory of Open Access Journals (Sweden)

    Yue Hao

    2017-01-01

    Full Text Available The energy performance and radial force of a mixed flow pump with symmetrical and unsymmetrical tip clearance are investigated in this paper. As the tip clearance increases, the pump head and efficiency both decrease. The center of the radial force on the principal axis is located at the coordinate origin when the tip clearance is symmetrical, and moves to the third quadrant when the tip clearance is unsymmetrical. Analysis results show that the total radial force on the principal axis is closely related to the fluctuation of mass flow rate in each single flow channel. Unsteady simulations show that the dominant frequencies of radial force on the hub and blade correspond to the blade number, vane number, or double blade number because of the rotor stator interaction. The radial force on the blade pressure side decreases with the tip clearance increase because of leakage flow. The unsymmetrical tip clearances in an impeller induce uneven leakage flow rate and then result in unsymmetrical work ability of each blade and flow pattern in each channel. Thus, the energy performance decreases and the total radial force increases for a mixed flow pump with unsymmetrical tip clearance.

  5. Development of unconfined conditions in multi-aquifer flow systems: a case study in the Rajshahi Barind, Bangladesh

    Science.gov (United States)

    Rushton, K. R.; Zaman, M. Asaduz

    2016-08-01

    Identifying flow processes in multi-aquifer flow systems is a considerable challenge, especially if substantial abstraction occurs. The Rajshahi Barind groundwater flow system in Bangladesh provides an example of the manner in which flow processes can change with time. At some locations there has been a decrease with time in groundwater heads and also in the magnitude of the seasonal fluctuations. This report describes the important stages in a detailed field and modelling study at a specific location in this groundwater flow system. To understand more about the changing conditions, piezometers were constructed in 2015 at different depths but the same location; water levels in these piezometers indicate the formation of an additional water table. Conceptual models are described which show how conditions have changed between the years 2000 and 2015. Following the formation of the additional water table, the aquifer system is conceptualised as two units. A pumping test is described with data collected during both the pumping and recovery phases. Pumping test data for the Lower Unit are analysed using a computational model with estimates of the aquifer parameters; the model also provided estimates of the quantity of water moving from the ground surface, through the Upper Unit, to provide an input to the Lower Unit. The reasons for the substantial changes in the groundwater heads are identified; monitoring of the recently formed additional water table provides a means of testing whether over-abstraction is occurring.

  6. A modal approach for vibration analysis and condition monitoring of a centrifugal pump

    Directory of Open Access Journals (Sweden)

    Ramana Podugu

    2011-08-01

    Full Text Available The modal analysis of the centrifugal pump and its assembly is performed using FEM technology. The mathematical model and FEA model are built for the original centrifugal casing and simulation is made to find the pump natural frequencies. The first ten natural frequencies were compared to pump operating speed and their multiples up to pump vane passing frequency as per HIS (Hydraulic Institute Standards -9.6.4-2000 guidelines. In the original design, the first natural frequency in vertical direction of the pump is found to be thecause for resonance at the first multiple speed of the pump. The first natural frequency of the original model was found to be 63.25 Hz which is very close to 62.5 Hz of the pump operating speed by a margin of 1.2%. As per HIS clause 9.6.4.4, the first natural frequency should be 10% above or below the pump operating speed. Finally, the model was modified by stiffening the pump pedestals and again FEA analysis was carried out to find the natural frequencies. As a result of modification in design, the first natural frequency was increased to 74.31Hz which is above 10% the pump operating speed i.e., 62.5 Hz. Hence, the results of the modified design aresatisfied with HIS clause. The results also show that the higher the stiffness of the pump, higher the natural frequency is.

  7. Simulation of the flow obstruction of a jet pump in a BWR reactor with the code RELAP/SCDAPSIM; Simulacion de la obstruccion de flujo de una bomba jet en un reactor BWR con el codigo RELAP/SCDAPSIM

    Energy Technology Data Exchange (ETDEWEB)

    Cardenas V, J.; Filio L, C., E-mail: jaime.cardenas@cnsns.gob.mx [Comision Nacional de Seguridad Nuclear y Salvaguardias, Dr. Jose M. Barragan 779, Col. Narvarte, 03020 Ciudad de Mexico (Mexico)

    2016-09-15

    This work simulates the flow obstruction of a jet pump in one of the recirculation loops of a nuclear power plant with a reactor of type BWR at 100% of operating power, in order to analyze the behavior of the total flow of the refrigerant passing through the reactor core, the total flow in each recirculation loop of the reactor, together with the 10 jet pumps of each loop. The behavior of the power and the reactivity insertion due to the change of the refrigerant flow pattern is also analyzed. The simulation was carried out using the RELAP/SCDAPSIM version 3.5 code, using a reactor model with 10 jet pumps in each recirculation loop and a core consisting of 6 radial zones and 25 axial zones. The scenario postulates the flow obstruction in a jet pump in a recirculation loop A when the reactor operates at 100% rated power, causing a change in the total flow of refrigerant in the reactor core, leading to a decrease in power. Once the reactor conditions are established to its new power, the operator tries to recover the nominal power using the flow control valve of the recirculation loop A, opening stepwise as a strategy to safely recover the reactor power. In this analysis is assumed that the intention of the nuclear plant operator is to maintain the operation of the reactor during the established cycle. (Author)

  8. The sponge pump: the role of current induced flow in the design of the sponge body plan.

    Directory of Open Access Journals (Sweden)

    Sally P Leys

    Full Text Available Sponges are suspension feeders that use flagellated collar-cells (choanocytes to actively filter a volume of water equivalent to many times their body volume each hour. Flow through sponges is thought to be enhanced by ambient current, which induces a pressure gradient across the sponge wall, but the underlying mechanism is still unknown. Studies of sponge filtration have estimated the energetic cost of pumping to be 0.75 with the ambient current velocity. During short bursts of high ambient current the sponges filtered two-thirds of the total volume of water they processed daily. Our model indicates that the head loss across the sponge collar filter is 10 times higher than previously estimated. The difference is due to the resistance created by a fine protein mesh that lines the collar, which demosponges also have, but was so far overlooked. Applying our model to the in situ measurements indicates that even modest pumping rates require an energetic expenditure of at least 28% of the total in situ respiration. We suggest that due to the high cost of pumping, current-induced flow is highly beneficial but may occur only in thin walled sponges living in high flow environments. Our results call for a new look at the mechanisms underlying current-induced flow and for reevaluation of the cost of biological pumping and its evolutionary role, especially in sponges.

  9. A quantitative visualization study of flow in a scaled-up model of a centrifugal blood pump.

    Science.gov (United States)

    Ikeda, T; Yamane, T; Orita, T; Tateishi, T

    1996-02-01

    A quantitative flow visualization study of a scaled-up model of a centrifugal blood pump was performed. Since the size of the scaled-up model was three times as large as the original pump under development, and the kinematic viscosity of the saline solution used as the working fluid was approximately one-third that of the blood, we obtained a similar flow at one twenty-seventh the angular velocity of the original pump. The flow was visualized by seeding the saline solution with neutrally buoyant particles and by illuminating the model with a laser light sheet. Since the gap flow behind the impeller is important for thrombus formation, it was recorded by a high-speed video camera, and the velocity field was evaluated automatically by particle tracking velocimetry. It was shown that in the gap behind the impeller there existed a region where the velocity profile was almost flat which can be called a core region. The results indicated the effectiveness of the present visualization technique for centrifugal blood pumps.

  10. Evaluation of near-wall solution approaches for large-eddy simulations of flow in a centrifugal pump impeller

    Directory of Open Access Journals (Sweden)

    Zhi-Feng Yao

    2016-01-01

    Full Text Available The turbulent flow in a centrifugal pump impeller is bounded by complex surfaces, including blades, a hub and a shroud. The primary challenge of the flow simulation arises from the generation of a boundary layer between the surface of the impeller and the moving fluid. The principal objective is to evaluate the near-wall solution approaches that are typically used to deal with the flow in the boundary layer for the large-eddy simulation (LES of a centrifugal pump impeller. Three near-wall solution approaches –the wall-function approach, the wall-resolved approach and the hybrid Reynolds averaged Navier–Stoke (RANS and LES approach – are tested. The simulation results are compared with experimental results conducted through particle imaging velocimetry (PIV and laser Doppler velocimetry (LDV. It is found that the wall-function approach is more sparing of computational resources, while the other two approaches have the important advantage of providing highly accurate boundary layer flow prediction. The hybrid RANS/LES approach is suitable for predicting steady-flow features, such as time-averaged velocities and hydraulic losses. Despite the fact that the wall-resolved approach is expensive in terms of computing resources, it exhibits a strong ability to capture a small-scale vortex and predict instantaneous velocity in the near-wall region in the impeller. The wall-resolved approach is thus recommended for the transient simulation of flows in centrifugal pump impellers.

  11. Flow separation in rocket nozzles under high altitude condition

    Science.gov (United States)

    Stark, R.; Génin, C.

    2017-01-01

    The knowledge of flow separation in rocket nozzles is crucial for rocket engine design and optimum performance. Typically, flow separation is studied under sea-level conditions. However, this disregards the change of the ambient density during ascent of a launcher. The ambient flow properties are an important factor concerning the design of altitude-adaptive rocket nozzles like the dual bell nozzle. For this reason an experimental study was carried out to study the influence of the ambient density on flow separation within conventional nozzles.

  12. Parametric study of fluid flow and heat transfer over louvered fins of air heat pump evaporator

    Science.gov (United States)

    Muszyński, Tomasz; Kozieł, Sławomir Marcin

    2016-09-01

    Two-dimensional numerical investigations of the fluid flow and heat transfer have been carried out for the laminar flow of the louvered fin-plate heat exchanger, designed to work as an air-source heat pump evaporator. The transferred heat and the pressure drop predicted by simulation have been compared with the corresponding experimental data taken from the literature. Two dimensional analyses of the louvered fins with varying geometry have been conducted. Simulations have been performed for different geometries with varying louver pitch, louver angle and different louver blade number. Constant inlet air temperature and varying velocity ranging from 2 to 8 m/s was assumed in the numerical experiments. The air-side performance is evaluated by calculating the temperature and the pressure drop ratio. Efficiency curves are obtained that can be used to select optimum louver geometry for the selected inlet parameters. A total of 363 different cases of various fin geometry for 7 different air velocities were investigated. The maximum heat transfer improvement interpreted in terms of the maximum efficiency has been obtained for the louver angle of 16 ° and the louver pitch of 1.35 mm. The presented results indicate that varying louver geometry might be a convenient way of enhancing performance of heat exchangers.

  13. Gas liquid flow at microgravity conditions - Flow patterns and their transitions

    Science.gov (United States)

    Dukler, A. E.; Fabre, J. A.; Mcquillen, J. B.; Vernon, R.

    1987-01-01

    The prediction of flow patterns during gas-liquid flow in conduits is central to the modern approach for modeling two phase flow and heat transfer. The mechanisms of transition are reasonably well understood for flow in pipes on earth where it has been shown that body forces largely control the behavior observed. This work explores the patterns which exist under conditions of microgravity when these body forces are suppressed. Data are presented which were obtained for air-water flow in tubes during drop tower experiments and Learjet trajectories. Preliminary models to explain the observed flow pattern map are evolved.

  14. Theoretical analysis of inertially irrotational and soleniodal flow in two-demensional radial flow pump and turbine impellers with equiangular blades

    NARCIS (Netherlands)

    Visser, F.C.; Brouwers, J.J.H.; Badie, R.

    1994-01-01

    Using the theory of functions of a complex variable, in particular the method of conformal mapping, the irrotational and solenoidal flow in two-dimensional radialflow pump and turbine impellers fitted with equiangular blades is analysed. Exact solutions are given for the fluid velocity along straigh

  15. The spiral groove bearing as a mechanism for enhancing the secondary flow in a centrifugal rotary blood pump.

    Science.gov (United States)

    Amaral, Felipe; Gross-Hardt, Sascha; Timms, Daniel; Egger, Christina; Steinseifer, Ulrich; Schmitz-Rode, Thomas

    2013-10-01

    The rapid evolution of rotary blood pump (RBP) technology in the last few decades was shaped by devices with increased durability, frequently employing magnetic or hydrodynamic suspension techniques. However, the potential for low flow in small gaps between the rotor and pump casing is still a problem for hemocompatibility. In this study, a spiral groove hydrodynamic bearing (SGB) is applied with two distinct objectives: first, as a mechanism to enhance the washout in the secondary flow path of a centrifugal RBP, lowering the exposure to high shear stresses and avoiding thrombus formation; and second, as a way to allow smaller gaps without compromising the washout, enhancing the overall pump efficiency. Computational fluid dynamics was applied and verified via bench-top experiments. An optimization of selected geometric parameters (groove angle, width and depth) focusing on the washout in the gap rather than generating suspension force was conducted. An optimized SGB geometry reduced the residence time of the cells in the gap from 31 to 27 ms, an improvement of 14% compared with the baseline geometry of 200 μm without grooves. When optimizing for pump performance, a 15% smaller gap yielded a slightly better rate of fluid exchange compared with the baseline, followed by a 22% reduction in the volumetric loss from the primary pathway. Finally, an improved washout can be achieved in a pulsatile environment due to the SGB ability to pump inwardly, even in the absence of a pressure head.

  16. Operating characteristics of isocaloric fountain-effect pumps

    Science.gov (United States)

    Kittel, Peter

    1988-01-01

    The governing equations of thermomechanical (fountain-effect) pumps are usually given for pumps operating at a constant temperature difference. These are the thermomechanical and mechanocaloric effects in which the pressure head and mass flow are independent of each other. Here, these equations are recast for a pump operating at a constant heat input (isocaloric). This form more closely represents how such pumps are likely to be used. Under these conditions, the pressure head and mass flow are shown to be related. For ideal pumps, the head and flow are related by a universal curve. For real pumps (those that have normal fluid leakage), a family of curves is developed. These curves approach the curve for an ideal pump at high flow rates. The isocaloric equations are also extended to multistage pumps.

  17. Investigations of unsteady flow in the draft tube of the pump- turbine model using laser Doppler anemometry

    Science.gov (United States)

    Kaznacheev, A.; Kuznetsov, I.

    2014-03-01

    The measurements and video observation of unsteady flow in the draft tube cone of the pump-turbine model were conducted in the Laboratory of Water Turbines, property of OJSC "Power machines" - "LMZ". The prototype head was about 250 m. The experiments were performed for the turbine mode of operation. Measurements were taken for the unit speed value n11 corresponding to rated head in the generating mode of operation, for a wide range of guide vanes openings at loads ranging from partial to maximum value. The researches of the velocity field in function of the Thoma number were carried out in some operating conditions. The mean values and RMS deviations of the velocity components were the results of laser measurements. The curves of the intensity of the vortex versus the guide vane opening and the Thoma number were plotted. The energy velocity spectra were presented for the points at which the most pronounced frequency precession of the helical axial vortex was observed. Video recording and laser Doppler anemometry were made in the operating conditions of the developed cavitation. Based on the results of video observations and energy spectra obtained via LDA, vortex frequencies were determined i.e. the frequencies of the vortex precession under the runner in the draft tube cone.

  18. Experimental Setup for Determining Ammonia-Salt Adsorption and Desorption Behavior Under Typical Heat Pump Conditions. Experimental Results

    Energy Technology Data Exchange (ETDEWEB)

    Van der Pal, M.; De Boer, R.; Veldhuis, J.B.J. [ECN Biomass and Energy Efficiency, Petten (Netherlands)

    2013-09-15

    For the aim of obtaining a better understanding of the performance of a salt-ammonia sorption reactor/heat exchanger a new test-rig was developed. This test-rig enables the measurement of the performance in adsorption and desorption mode of different sorption reactor designs. It measures the speed of uptake and release of ammonia gas of various salt-ammonia reactions under well-controlled and well-monitored process conditions, similar to the heat pump conditions. The test-rig measures the ammonia uptake and release under controlled pressure and temperature conditions. Temperatures of the salt reactor can be varied from ambient temperature up to 200{sup o}C and the ammonia pressure can be varied between 0.02 to 2 MPa. These conditions can be set independently and repeated at regular time-intervals. Besides NH3-mass-flow meters, pressure and temperature sensors, the setup also contains an endoscope to observe any macroscopic structural changes in the material during uptake and release of ammonia. Measurements so far have shown a liquid phase of LiCl.3NH3 at pressures of 0.5 MPa and temperatures exceeding 90{sup o}C. Voilent foaming is observed at 120{sup o}C resulting in salt losses. A correlation was determined between the reaction rate of MgCl{sub 2}(2-6)NH3 and the relative pressure gradient yielding a reaction time of about 1500 seconds for a relative pressure difference of 1. Multiple sorption cycles of the CaCl{sub 2}(2-4)NH3 reaction, showed a reduced activity from 85% of the theoretical maximum sorbed mass at the first sorption cycle, to 15% after 300+ cycles.

  19. An Integrated Approach on Groundwater Flow and Heat/Solute Transport for Sustainable Groundwater Source Heat Pump (GWHP) System Operation

    Science.gov (United States)

    Park, D. K.; Bae, G. O.; Joun, W.; Park, B. H.; Park, J.; Park, I.; Lee, K. K.

    2015-12-01

    The GWHP system uses a stable temperature of groundwater for cooling and heating in buildings and thus has been known as one of the most energy-saving and cost-efficient renewable energy techniques. A GWHP facility was installed at an island located at the confluence of North Han and South Han rivers, Korea. Because of well-developed alluvium, the aquifer is suitable for application of this system, extracting and injecting a large amount of groundwater. However, the numerical experiments under various operational conditions showed that it could be vulnerable to thermal interference due to the highly permeable gravel layer, as a preferential path of thermal plume migration, and limited space for well installation. Thus, regional groundwater flow must be an important factor of consideration for the efficient operation under these conditions but was found to be not simple in this site. While the groundwater level in this site totally depends on the river stage control of Paldang dam, the direction and velocity of the regional groundwater flow, observed using the colloidal borescope, have been changed hour by hour with the combined flows of both the rivers. During the pumping and injection tests, the water discharges in Cheongpyeong dam affected their respective results. Moreover, the measured NO3-N concentrations might imply the effect of agricultural activities around the facility on the groundwater quality along the regional flow. It is obvious that the extraction and injection of groundwater during the facility operation will affect the fate of the agricultural contaminants. Particularly, the gravel layer must also be a main path for contaminant migration. The simulations for contaminant transport during the facility operation showed that the operation strategy for only thermal efficiency could be unsafe and unstable in respect of groundwater quality. All these results concluded that the integrated approach on groundwater flow and heat/solute transport is necessary

  20. On the aquitard-aquifer interface flow and the drawdown sensitivity with a partially penetrating pumping well in an anisotropic leaky confined aquifer

    Science.gov (United States)

    Feng, Qinggao; Zhan, Hongbin

    2015-02-01

    A mathematical model for describing groundwater flow to a partially penetrating pumping well of a finite diameter in an anisotropic leaky confined aquifer is developed. The model accounts for the jointed effects of aquitard storage, aquifer anisotropy, and wellbore storage by treating the aquitard leakage as a boundary condition at the aquitard-aquifer interface rather than a volumetric source/sink term in the governing equation, which has never developed before. A new semi-analytical solution for the model is obtained by the Laplace transform in conjunction with separation of variables. Specific attention was paid on the flow across the aquitard-aquifer interface, which is of concern if aquitard and aquifer have different pore water chemistry. Moreover, Laplace-domain and steady-state solutions are obtained to calculate the rate and volume of (total) leakage through the aquitard-aquifer interface due to pump in a partially penetrating well, which is also useful for engineers to manager water resources. The sensitivity analyses for the drawdown illustrate that the drawdown is most sensitive to the well partial penetration. It is apparently sensitive to the aquifer anisotropic ratio over the entire time of pumping. It is moderately sensitive to the aquitard/aquifer specific storage ratio at the intermediate times only. It is moderately sensitive to the aquitard/aquifer vertical hydraulic conductivity ratio and the aquitard/aquifer thickness ratio with the identical influence at late times.

  1. Internal Flow Characteristics of a Centrifugal Pump with Very Low Specific Speed

    OpenAIRE

    Choi, Young-Do; Kurokawa, Junichi; Matsui, Jun; Imamura, Hiroshi

    2002-01-01

    In the very low specific-speed range (Ns < 100[m,m3/min, rpm]), the efficiency of turbo-pump designed by conventional method becomes remarkably low. Therefore, positive-displacement pumps have long been used widely. However, the positive-displacement pumps have problems such as noise, vibration and need high manufacturing precision. Recently, since the turbo-pumps are becoming higher in rotational speed and smaller in size, there are lots of expectation of developing new turbo-pump with high ...

  2. A multi-phase ferrofluid flow model with equation of state for thermomagnetic pumping and heat transfer

    CERN Document Server

    Aursand, Eskil; Lervåg, Karl Yngve; Lund, Halvor

    2016-01-01

    A one-dimensional multi-phase flow model for thermomagnetically pumped ferrofluid with heat transfer is proposed. The thermodynamic model is a combination of a simplified particle model and thermodynamic equations of state for the base fluid. The magnetization model is based on statistical mechanics, taking into account non-uniform particle size distributions. An implementation of the proposed model is validated against experiments from the literature, and found to give good predictions for the thermomagnetic pumping performance. However, the results reveal a very large sensitivity to uncertainties in heat transfer coefficient predictions.

  3. Transient Flows in a Pipe System with Pump Shut-Down and the Simultaneous Closing of a Spherical Valve

    Science.gov (United States)

    Zhang, Zh.

    2016-11-01

    Because of the limited value of the wave propagation speed in water the propagation of a pressure surge in transient flows can be tracked in the time series. This enables both the pressure head and the flow velocity in pipe flows to be determined as a function of both the coordinate along the pipe and the time. The propagation of the pressure surge includes both wave transmission and reflection. The latter occurs where the flow section is changed. The wave tracking method has been demonstrated as highly accurate and subsequently was applied to much more complex hydraulic systems, in which the pump is shut off and the spherical valve is simultaneously progressively closed. A combined four-quadrant characteristic of the pump and a spherical valve has been worked out, with which the computational procedure for the transient flow in the complex system could be significantly simplified. It has been demonstrated that not only the pressure surge in the hydraulic system but also the rotational speed of the pump could be satisfactorily computed. The computational algorithm has been demonstrated as quite simple, so that all calculations could be performed simply by means of the Microsoft Excel module.

  4. Micro Flow Cytometer Chip Integrated with Micro-Pumps/Micro-Valves for Multi-Wavelength Cell Counting and Sorting

    Science.gov (United States)

    Chang, Chen-Min; Hsiung, Suz-Kai; Lee, Gwo-Bin

    2007-05-01

    Flow cytometry is a popular technique for counting and sorting of individual cells. This study presents a new chip-based flow cytometer capable of cell injection, counting and switching in an automatic format. The new microfluidic system is also capable of multi-wavelength detection of fluorescence-labeled cells by integrating multiple buried optical fibers within the chip. Instead of using large-scale syringe pumps, this study integrates micro-pumps and micro-valves to automate the entire cell injection and sorting process. By using pneumatic serpentine-shape (S-shape) micro-pumps to drive sample and sheath flows, the developed chip can generate hydrodynamic focusing to allow cells to pass detection regions in sequence. Two pairs of optical fibers are buried and aligned with the microchannels, which can transmit laser light sources with different wavelengths and can collect induced fluorescence signals. The cells labeled with different fluorescent dyes can be excited by the corresponding light source at different wavelengths. The fluorescence signals are then collected by avalanche photodiode (APD) sensors. Finally, a flow switching device composed of three pneumatic micro-valves is used for cell sorting function. Experimental data show that the developed flow cytometer can distinguish specific cells with different dye-labeling from mixed cell samples in one single process. The target cell samples can be also switched into appropriate outlet channels utilizing the proposed microvalve device. The developed microfluidic system is promising for miniature cell-based biomedical applications.

  5. Pump-flow-probe x-ray absorption spectroscopy as a tool for studying aintermediate states of photocatalytic systems

    DEFF Research Database (Denmark)

    Smolentsev, Grigory; Guda, Alexander; Zhang, Xiaoyi

    2013-01-01

    A new setup for pump-flow-probe X-ray absorption spectroscopy has been implemented at the SuperXAS beamline of the Swiss Light Source. It allows recording X-ray absorption spectra with a time resolution of tens of microseconds and high detection efficiency for samples with sub-millimolar concentr......A new setup for pump-flow-probe X-ray absorption spectroscopy has been implemented at the SuperXAS beamline of the Swiss Light Source. It allows recording X-ray absorption spectra with a time resolution of tens of microseconds and high detection efficiency for samples with sub......-millimolar concentrations. A continuous wave laser is used for the photoexcitation, with the distance between laser and X-ray beams and velocity of liquid flow determining the time delay, while the focusing of both beams and the flow speed profile define the time resolution. This method is compared with the alternative...... measurement technique that utilizes a 1 kHz repetition rate laser and multiple X-ray probe pulses. Such an experiment was performed at beamline 11ID-D of the Advanced Photon Source. Advantages, limitations, and potential for improvement of the pump-flow-probe setup are discussed by analyzing the photon...

  6. EFFECT OF THE CRITICAL IRRADIANCE ON PHOTOVOLTAIC WATER PUMP DISCHARGE UNDER EGYPTIAN CONDITIONS

    Directory of Open Access Journals (Sweden)

    Mamdouh Abbas HELMY

    2015-04-01

    Full Text Available The present investigation aimed to study the effect of critical irradiance due to changing tilt angle of PV panel and tracking sun on submersible pump discharge. The authors used solar tracker and suitable tilt angle for the panel to increase the time interval during which the water pump operates. For the same irradiance collected by the PV, all systems pump the same amount of water, although they occur at different periods of the day. The pump itself 'does not know whether the electric power comes from any processes, as long as it has the same intensity.

  7. Simultaneous effects of Hall and convective conditions on peristaltic flow of couple-stress fluid in an inclined asymmetric channel

    Indian Academy of Sciences (India)

    T Hayat; Maryam Iqbal; Humaira Yasmin; Fuad E Alsaadi; Huijun Gao

    2015-07-01

    A mathematical model is developed to analyse the peristaltic flow of couple-stress fluid in an inclined asymmetric channel with convective conditions. Soret and Dufour and Hall effects are taken into account. Analysis has been carried out in a wave frame of reference. Expressions for velocity, pressure gradient, temperature and concentration are constructed. Pumping and trapping phenomena are examined. Impact of sundry parameters on the velocity, temperature and concentration is discussed.

  8. 轴流泵水力模型内部流场数值模拟%Numerical simulation of internal flow field in hydraulic model of axial-flow pump

    Institute of Scientific and Technical Information of China (English)

    齐学义; 汪玮华; 郝连松

    2012-01-01

    Based on the Reynolds time-averaged Navier-Stokes equations with turbulence mode, by using SIMPLEC algorithm to make pressure-velocity coupling, and by using the implicit different format with second-order accuracy, the stationary 3-D turbulent flow in axial-flow pump was numerically simulated and the velocity vectors, static pressure contours, and other flow informations were obtained. The simulation result showed that the flow field distribution and flow form were better in general in design condition, but a local low pressure area occurred at the inlet of impeller blade back near the wheel rim and the load on the outer wall of guide vane was large, indicating that it would be necessary to improve the axial-flow pump model and pump performance.%基于Reynolds时均N-S方程,采用标准k-ε湍流模型,压力、速度耦合使用SIMPLEC算法,离散采用具有二阶精度的隐式格式差分,对轴流泵过流部件内部流场进行三维定常湍流数值模拟,得到泵内流动的速度和压力矢量分布图,以及其他一些流动的信息.数值模拟结果表明,设计工况下的流场分布和流态总体较好,但叶轮叶片背面进口靠近轮缘处出现局部低压,导叶外壁区域负荷大,说明该轴流泵水力模型还有进一步改进和对其性能进一步提高的必要.

  9. Gas Engine-Driven Heat Pump Chiller for Air-Conditioning and Hot Water Supply Systems

    Science.gov (United States)

    Fujita, Toshihiko; Mita, Nobuhiro; Moriyama, Tadashi; Hoshino, Norimasa; Kimura, Yoshihisa

    In Part 1 of this study, the performance characteristics of a 457kW gas engine-driven heat pump (GHP) chiller have been obtained from a simulation model analysis for both cooling and heating modes and it has been found that the part-load characteristics of the GHP chiller are fairly well. On the back of Part 1, a computer simulation program has been developed for the evaluation of GHP chiller systems to compare with the other types of heat source systems for air-conditioning and hot water supply applications. The simulation program can be used to estimate annual energy consumption, annual CO2 emission, etc. of the systems with the data of monthly and hourly thermal loads on various buildings, outdoor air conditions, and characteristics of various components comprising the systems. By applying this to some cases of medium-scale hotel, office, shop, and hospital buildings, it has been found that the GHP chiller systems have advantages particularly in the cases of hotels and hospitals where a lot of hot water demand exists. It has also been found that the combination of a GHP chiller and a direct-fired absorption water chiller boiler (hot and chilled water generator) appears promising.

  10. Verification of the karst flow model under laboratory controlled conditions

    Science.gov (United States)

    Gotovac, Hrvoje; Andric, Ivo; Malenica, Luka; Srzic, Veljko

    2016-04-01

    Karst aquifers are very important groundwater resources around the world as well as in coastal part of Croatia. They consist of extremely complex structure defining by slow and laminar porous medium and small fissures and usually fast turbulent conduits/karst channels. Except simple lumped hydrological models that ignore high karst heterogeneity, full hydraulic (distributive) models have been developed exclusively by conventional finite element and finite volume elements considering complete karst heterogeneity structure that improves our understanding of complex processes in karst. Groundwater flow modeling in complex karst aquifers are faced by many difficulties such as a lack of heterogeneity knowledge (especially conduits), resolution of different spatial/temporal scales, connectivity between matrix and conduits, setting of appropriate boundary conditions and many others. Particular problem of karst flow modeling is verification of distributive models under real aquifer conditions due to lack of above-mentioned information. Therefore, we will show here possibility to verify karst flow models under the laboratory controlled conditions. Special 3-D karst flow model (5.6*2.6*2 m) consists of concrete construction, rainfall platform, 74 piezometers, 2 reservoirs and other supply equipment. Model is filled by fine sand (3-D porous matrix) and drainage plastic pipes (1-D conduits). This model enables knowledge of full heterogeneity structure including position of different sand layers as well as conduits location and geometry. Moreover, we know geometry of conduits perforation that enable analysis of interaction between matrix and conduits. In addition, pressure and precipitation distribution and discharge flow rates from both phases can be measured very accurately. These possibilities are not present in real sites what this model makes much more useful for karst flow modeling. Many experiments were performed under different controlled conditions such as different

  11. Investigation on the influence of leakage clearance on the flow field and performance of scroll hydraulic pump

    Science.gov (United States)

    Sun, Shuaihui; Huang, Yi; Guo, Pengcheng; Zuo, Juanli; Luo, Xingqi

    2016-11-01

    In the present paper, the computer fluid dynamics(CFD) with dynamic mesh model had been applied in scroll hydraulic pump to obtain its flow field at different leakage clearance. The fluid force on the orbiting scroll, the mass flow rate and the hydraulic efficiency at different leakage clearance were calculated based on the flow field data. The results indicated that when the leakage clearance increased from 0.5mm to 1.5mm, the average pressure, maximum of pressure fluctuation, leakage jet flow velocity, shaft power, cavitation degree decreased and the leakage flow rate increased. If the leakage clearance was 2.0mm, the high pressure discharge fluid flowed through the clearance and led to the increase of the average pressure and fluid force. When the leakage clearance is 1.0mm, the average pressure is far lower than that at the 0.5mm clearance, and the hydraulic efficiency is the highest.

  12. Effect of pumping chamber on performance of non-overload centrifugal pump

    Institute of Scientific and Technical Information of China (English)

    谷云庆; 吴登昊; 牟介刚; 蒋兰芳; 代东顺; 施瀚昱; 郑水华

    2015-01-01

    In order to specify the characteristics of un-overloaded centrifugal pumps, the IH100-65-200 pump was chosen as the model pump. Different calculation models for centrifugal pumps were established under different pumping chamber sectional parameters. In the numerical simulation of the centrifugal pumps flow field, the shaft power, head, efficiency, and the changes of the internal flow field under different sectional areas and sectional shapes were studied with the RNGk−εturbulence model, and the influence of the pumping chamber section characteristics of the non-overloaded centrifugal pumps were analyzed. The results show that sectional areas have a significant impact on the non-overload characteristics of centrifugal pumps. The shaft power and head of centrifugal pump are increasing with a lager sectional area, by which the gradient of head curves decreases. The efficiency is improved under a large flow rate condition, but the head and the efficiency are reduced at a small flow rate. It is also observed that the sectional shapes have less influence on the shaft power, the hydraulic performance and flow field characteristics of a centrifugal pump.

  13. Mitigation potential of horizontal ground coupled heat pumps for current and future climatic conditions: UK environmental modelling and monitoring studies

    Science.gov (United States)

    García González, Raquel; Verhoef, Anne; Vidale, Pier Luigi; Gan, Guohui; Wu, Yupeng; Hughes, Andrew; Mansour, Majdi; Blyth, Eleanor; Finch, Jon; Main, Bruce

    2010-05-01

    An increased uptake of alternative low or non-CO2 emitting energy sources is one of the key priorities for policy makers to mitigate the effects of environmental change. Relatively little work has been undertaken on the mitigation potential of Ground Coupled Heat Pumps (GCHPs) despite the fact that a GCHP could significantly reduce CO2 emissions from heating systems. It is predicted that under climate change the most probable scenario is for UK temperatures to increase and for winter rainfall to become more abundant; the latter is likely to cause a general rise in groundwater levels. Summer rainfall may reduce considerably, while vegetation type and density may change. Furthermore, recent studies underline the likelihood of an increase in the number of heat waves. Under such a scenario, GCHPs will increasingly be used for cooling as well as heating. These factors will affect long-term performance of horizontal GCHP systems and hence their economic viability and mitigation potential during their life span ( 50 years). The seasonal temperature differences encountered in soil are harnessed by GCHPs to provide heating in the winter and cooling in the summer. The performance of a GCHP system will depend on technical factors (heat exchanger (HE) type, length, depth, and spacing of pipes), but also it will be determined to a large extent by interactions between the below-ground parts of the system and the environment (atmospheric conditions, vegetation and soil characteristics). Depending on the balance between extraction and rejection of heat from and to the ground, the soil temperature in the neighbourhood of the HE may fall or rise. The GROMIT project (GROund coupled heat pumps MITigation potential), funded by the Natural Environment Research Council (UK), is a multi-disciplinary research project, in collaboration with EarthEnergy Ltd., which aims to quantify the CO2 mitigation potential of horizontal GCHPs. It considers changing environmental conditions and combines

  14. Empirical Platform Data Analysis to Investigate how Heat Pumps Operate in Real-Life Conditions

    DEFF Research Database (Denmark)

    Carmo, Carolina; Elmegaard, Brian; Nielsen, M. P.

    2015-01-01

    Heat pumps have been widely acknowledged, by academia and industry, as highly efficient thermal energy technologies, for space heating and domestic hot water production. However, there is a lack of information about real performance in residential single family houses with active participation...... the suitability of heat pumps to support fossil-fuel free energy systems....

  15. 混流泵水动力噪声的数值预报方法%Numerical predicting method for hydroacoustics of mixed-flow pump

    Institute of Scientific and Technical Information of China (English)

    付建; 王永生; 靳栓宝

    2016-01-01

    In order to predict the hydroacoustics of mixed-flow pump accurately, the flow noise of stationary wall was calculated based on boundary element method (BEM) and the noise of rotating source was calculated based on point source model. The numerical result is well in agreement with the data from experiment or reference. After that the fluctuation pressure distribution of a mixed-flow pump was simulated using large eddy simulation (LES), and then the hydroacoustics of stationary component and rotating component of pump were analyzed on the condition that the pump noise was equal to the sum of two components noise. The results show that the biggest fluctuation pressure of stationary component is located in the blade-stator interaction area and the peak value of noise caused by stationary part is in BPF and stator passing frequency and their harmonics. The noise in mixed-flow pump inlet is mainly caused by impeller. The contribution of stationary component can be neglected.%为了准确预报分析混流泵的水动力噪声,首先结合边界元法和点源模型理论完成静止壁面流噪声和任意边界条件下旋转声源噪声的数值计算与结果校验;然后以某混流泵为对象利用大涡模拟方法得到泵固体壁面脉动压力分布,在此基础上分别计算混流泵静止部件和旋转部件的水动力噪声,最后对二者声场进行叠加即得到了混流泵总声场。研究结果表明:混流泵静止壁面脉动压力幅值最强位置在叶轮与导叶的相互作用区域;静止部件对应的噪声峰值频率主要在叶频、导叶通过频率以及二者的谐频处;在混流泵进口截面叶轮引起的噪声占主要成分,静止部件的贡献可以忽略。

  16. Groundwater flow modelling under ice sheet conditions. Scoping calculations

    Energy Technology Data Exchange (ETDEWEB)

    Jaquet, O.; Namar, R. (In2Earth Modelling Ltd (Switzerland)); Jansson, P. (Dept. of Physical Geography and Quaternary Geology, Stockholm Univ., Stockholm (Sweden))

    2010-10-15

    The potential impact of long-term climate changes has to be evaluated with respect to repository performance and safety. In particular, glacial periods of advancing and retreating ice sheet and prolonged permafrost conditions are likely to occur over the repository site. The growth and decay of ice sheets and the associated distribution of permafrost will affect the groundwater flow field and its composition. As large changes may take place, the understanding of groundwater flow patterns in connection to glaciations is an important issue for the geological disposal at long term. During a glacial period, the performance of the repository could be weakened by some of the following conditions and associated processes: - Maximum pressure at repository depth (canister failure). - Maximum permafrost depth (canister failure, buffer function). - Concentration of groundwater oxygen (canister corrosion). - Groundwater salinity (buffer stability). - Glacially induced earthquakes (canister failure). Therefore, the GAP project aims at understanding key hydrogeological issues as well as answering specific questions: - Regional groundwater flow system under ice sheet conditions. - Flow and infiltration conditions at the ice sheet bed. - Penetration depth of glacial meltwater into the bedrock. - Water chemical composition at repository depth in presence of glacial effects. - Role of the taliks, located in front of the ice sheet, likely to act as potential discharge zones of deep groundwater flow. - Influence of permafrost distribution on the groundwater flow system in relation to build-up and thawing periods. - Consequences of glacially induced earthquakes on the groundwater flow system. Some answers will be provided by the field data and investigations; the integration of the information and the dynamic characterisation of the key processes will be obtained using numerical modelling. Since most of the data are not yet available, some scoping calculations are performed using the

  17. STOCHASTIC ANALYSIS OF GROUNDWATER FLOW SUBJECT TO RANDOM BOUNDARY CONDITIONS

    Institute of Scientific and Technical Information of China (English)

    SHI Liang-sheng; YANG Jin-zhong; CAI Shu-ying; LIN Lin

    2008-01-01

    A stochastic model was developed to simulate the flow in heterogeneous media subject to random boundary conditions.Approximate partial differential equations were derived based on the Karhunen-Loeve (KL) expansion and perturbation expansion. The effect of random boundary conditions on the two-dimensional flow was examined. It is shown that the proposed stochastic model is efficient to include the random boundary conditions. The random boundaries lead to the increase of head variance and velocity variance. The influence of the random boundary conditions on head uncertainty is exerted over the whole simulated region, while the randomness of the boundary conditions leads to the increase of the velocity variance in the vicinity of boundaries.

  18. A study of unsteady physiological magneto-fluid flow and heat transfer through a finite length channel by peristaltic pumping.

    Science.gov (United States)

    Tripathi, Dharmendra; Bég, O Anwar

    2012-08-01

    Magnetohydrodynamic peristaltic flows arise in controlled magnetic drug targeting, hybrid haemodynamic pumps and biomagnetic phenomena interacting with the human digestive system. Motivated by the objective of improving an understanding of the complex fluid dynamics in such flows, we consider in the present article the transient magneto-fluid flow and heat transfer through a finite length channel by peristaltic pumping. Reynolds number is small enough and the wavelength to diameter ratio is large enough to negate inertial effects. Analytical solutions for temperature field, axial velocity, transverse velocity, pressure gradient, local wall shear stress, volume flowrate and averaged volume flowrate are obtained. The effects of the transverse magnetic field, Grashof number and thermal conductivity on the flow patterns induced by peristaltic waves (sinusoidal propagation along the length of channel) are studied using graphical plots. The present study identifies that greater pressure is required to propel the magneto-fluid by peristaltic pumping in comparison to a non-conducting Newtonian fluid, whereas, a lower pressure is required if heat transfer is effective. The analytical solutions further provide an important benchmark for future numerical simulations.

  19. Impact of Ducting on Heat Pump Water Heater Space Conditioning Energy Use and Comfort

    Energy Technology Data Exchange (ETDEWEB)

    Widder, Sarah H.; Petersen, Joseph M.; Parker, Graham B.; Baechler, Michael C.

    2014-07-21

    Increasing penetration of heat pump water heaters (HPWHs) in the residential sector will offer an important opportunity for energy savings, with a theoretical energy savings of up to 63% per water heater and up to 11% of residential energy use (EIA 2009). However, significant barriers must be overcome before this technology will reach widespread adoption in the Pacific Northwest region and nationwide. One significant barrier noted by the Northwest Energy Efficiency Alliance (NEEA) is the possible interaction with the homes’ space conditioning system for units installed in conditioned spaces. Such complex interactions may decrease the magnitude of whole-house savings available from HPWH installed in the conditioned space in cold climates and could lead to comfort concerns (Larson et al. 2011; Kresta 2012). Modeling studies indicate that the installation location of HPWHs can significantly impact their performance and the resultant whole-house energy savings (Larson et al. 2012; Maguire et al. 2013). However, field data are not currently available to validate these results. This field evaluation of two GE GeoSpring HPWHs in the PNNL Lab Homes is designed to measure the performance and impact on the Lab Home HVAC system of a GE GeoSpring HPWH configured with exhaust ducting compared to an unducted GeoSpring HPWH during heating and cooling season periods; and measure the performance and impact on the Lab Home HVAC system of the GeoSpring HPWH with both supply and exhaust air ducting as compared to an unducted GeoSpring HPWH during heating and cooling season periods. Important metrics evaluated in these experiments include water heater energy use, HVAC energy use, whole house energy use, interior temperatures (as a proxy for thermal comfort), and cost impacts. This technical report presents results from the PNNL Lab Homes experiment.

  20. Stem sap flow in plants under low gravity conditions

    Science.gov (United States)

    Tokuda, Ayako; Hirai, Hiroaki; Kitaya, Yoshiaki

    2016-07-01

    A study was conducted to obtain a fundamental knowledge for plant functions in bio-regenerative life support systems in space. Stem sap flow in plants is important indicators for water transport from roots to atmosphere through leaves. In this study, stem sap flow in sweetpotato was assessed at gravity levels from 0.01 to 2 g for about 20 seconds each during parabolic airplane flights. Stem sap flow was monitored with a heat balance method in which heat generated with a tiny heater installed in the stem was transferred upstream and downstream by conduction and upstream by convection with the sap flow through xylems of the vascular tissue. Thermal images of stem surfaces near heated points were captured using infrared thermography and the internal heat convection corresponding to the sap flow was analyzed. In results, the sap flow in stems was suppressed more at lower gravity levels without forced air circulation. No suppression of the stem sap flow was observed with forced air circulation. Suppressed sap flow in stems would be caused by suppression of transpiration in leaves and would cause restriction of water and nutrient uptake in roots. The forced air movement is essential to culture healthy plants at a high growth rate under low gravity conditions in space.

  1. Numerical Research about Influence of Blade Outlet Angle on Flow-Induced Noise and Vibration for Centrifugal Pump

    Directory of Open Access Journals (Sweden)

    Ailing Yang

    2014-03-01

    Full Text Available A hybrid numerical method was used to calculate the flow-induced noise and vibration of the centrifugal pump in the paper. The unsteady flows inside the centrifugal pumps with different blade outlet angles were simulated firstly. The unsteady pressure on the inner surface of the volute and the unsteady force applied on the impeller were analyzed. Then the vibration of the volute and sound field were calculated based on an acoustic-vibro-coupling method. The results show that the pump head has increased 7% while the hydraulic efficiency decreased 11.75% as blade outlet angles increased from 18° to 39°. The amplitude of pressure fluctuation at the first blade passing frequency has decreased but increased at the second-order blade passing frequency as the angle growing. The total fluctuation power near volute tongue goes up about 12% every 3° increment of blade outlet angle. The results also show that vibrating-velocity of the volute at second-order blade passing frequency is much higher than at other frequencies, and the velocity increases rapidly as blade outlet angle varies from 18° to 39°. At the same time, the sound pressure level outside the pump has increased about 8.6 dB when the angle increased from 18° to 39°.

  2. Flux change in viscous laminar flow under oscillating boundary condition

    Science.gov (United States)

    Ueda, R.; Mikada, H.; Goto, T.; Takekawa, J.

    2012-12-01

    The behavior of interstitial fluid is one of major interest in earth sciences in terms of the exploitation of water resources, the initiation of earthquakes, enhanced oil recovery (EOR), etc. Seismic waves are often known to increase the flux of interstitial fluid but the relationship between the flux and propagating seismic waves have not been well investigated in the past, although seismic stimulation has been applied in the oil industry for enhanced oil recovery (EOR). Many observations indicated that seismic waves could stimulate the oil production due to lowering of apparent viscosity coefficient, to the coalescence and/or the dispersion of droplets of a phase in multiphase fluids. However, the detailed mechanism of seismic stimulation has not been fully understood, either. In this study, We attempt to understand the mechanism of the flux change in viscous laminar flow under oscillating boundary condition for the simulation of interstitial flow. Here, we analyze a monophase flow in a pore throat. We first assume a Hagen-Poiseuille flow of incompressible fluid through a pore-throat in a porous medium. We adopt the Lattice Boltzmann method (LBM) in which the motion of fluid is simulated through the variation of velocity distribution function representing the distribution of discrete particle velocities. We use an improved incompressible LBKG model (d2q9i) proposed in Zou et. al. (1995) to accurately accommodate the boundary conditions of pressure and velocity in the Hagen-Poiseuille flow. We also use an half-way bounce back boundary condition as the velocity boundary condition. Also, we assume a uniform pressure (density) difference between inlet and outlet flow, and the density difference could initiate the flow in our simulation. The oscillating boundary condition is given by the body force acting on fluid particles. In this simulation, we found that the flux change is negligible under small amplitude of oscillation in both horizontal and vertical directions

  3. Central and peripheral blood flow during exercise with a continuous-flow left ventricular assist device: constant versus increasing pump speed: a pilot study

    DEFF Research Database (Denmark)

    Brassard, Patrice; Jensen, Annette S; Nordsborg, Nikolai

    2011-01-01

    with work rate would increase organ blood flow. Methods and Results- Invasively determined CO and leg blood flow and Doppler-determined cerebral perfusion were measured during 2 incremental cycle exercise tests on the same day in 8 patients provided with a HeartMate II LVAD. In random order, patients......Background- End-stage heart failure is associated with impaired cardiac output (CO) and organ blood flow. We determined whether CO and peripheral perfusion are maintained during exercise in patients with an axial-flow left ventricular assist device (LVAD) and whether an increase in LVAD pump speed...... exercised both with a constant (˜9775 rpm) and with an increasing pump speed (+400 rpm per exercise stage). At 60 W, the elevation in CO was more pronounced with increased pump speed (8.7±0.6 versus 8.1±1.1 L · min(-1); mean±SD; P=0.05), but at maximal exercise increases in CO (from 7.0±0.9 to 13.6±2.5 L...

  4. Flow Field Characterization Inside an Arteriovenous Graft-to-Vein Anastomosis Under Pulsatile Flow Conditions

    Science.gov (United States)

    2007-11-02

    1 FLOW FIELD CHARACTERIZATION INSIDE AN ARTERIOVENOUS GRAFT- TO-VEIN ANASTOMOSIS UNDER PULSATILE FLOW CONDITIONS Nurullah Arslan1, Francis Loth2...the relationship between the distribution of turbulence intensity and the localization of stenoses inside the venous anastomosis of arteriovenous (A...found to be greatest downstream of the anastomosis . KEYWORDS: Arteriovenous graft, dialysis, turbulence, stenosis I. INTRODUCTION

  5. Distributions and activities of ammonia oxidizing bacteria and polyphosphate accumulating organisms in a pumped-flow biofilm reactor.

    Science.gov (United States)

    Wu, Guangxue; Nielsen, Michael; Sorensen, Ketil; Zhan, Xinmin; Rodgers, Michael

    2009-10-01

    The spatial distributions and activities of ammonia oxidizing bacteria (AOB) and polyphosphate accumulating organisms (PAOs) were investigated for a novel laboratory-scale sequencing batch pumped-flow biofilm reactor (PFBR) system that was operated for carbon, nitrogen and phosphorus removal. The PFBR comprised of two 16.5l tanks (Reactors 1 and 2), each with a biofilm module of 2m(2) surface area. To facilitate the growth of AOB and PAOs in the reactor biofilms, the influent wastewater was held in Reactor 1 under stagnant un-aerated conditions for 6 h after feeding, and was then pumped over and back between Reactors 1 and 2 for 12 h, creating aerobic conditions in the two reactors during this period; as a consequence, the biofilm in Reactor 2 was in an aerobic environment for almost all the 18.2 h operating cycle. A combination of micro-sensor measurements, molecular techniques, batch experiments and reactor studies were carried out to analyse the performance of the PFBR system. After 100 days operation at a filtered chemical oxygen demand (COD(f)) loading rate of 3.46 g/m(2) per day, the removal efficiencies were 95% COD(f), 87% TN(f) and 74% TP(f). While the PFBR microbial community structure and function were found to be highly diversified with substantial AOB and PAO populations, about 70% of the phosphorus release potential and almost 100% of the nitrification potential were located in Reactors 1 and 2, respectively. Co-enrichment of AOB and PAOs was realized in the Reactor 2 biofilm, where molecular analyses revealed unexpected microbial distributions at micro-scale, with population peaks of AOB in a 100-250 microm deep sub-surface zone and of PAOs in the 0-150 microm surface zone. The micro-distribution of AOB coincided with the position of the nitrification peak identified during micro-sensor analyses. The study demonstrates that enrichment of PAOs can be realized in a constant or near constant aerobic biofilm environment. Furthermore, the findings suggest

  6. Numerical Investigation on Hydrodynamic Characteristics of a Centrifugal Pump with a Double Volute at Off-Design Conditions

    Science.gov (United States)

    Shim, H. S.; Kim, K. Y.

    2016-11-01

    Severe radial thrust under off-design operating conditions can be harmful factor for centrifugal pumps. In the present work, effects of geometry of a double volute casing on the hydrodynamic performance of a centrifugal pump have been investigated focusing on off-design conditions. Three-dimensional steady Reynolds-averaged Navier-Stokes analysis was carried out by using shear stress transport turbulence model. Numerical results for the hydrodynamic performance of the centrifugal pump were validated compared with experimental data. The hydraulic efficiency and radial thrust coefficient were used as performance parameters to evaluate the hydrodynamic characteristics of the centrifugal pump. The cross-sectional area ratio of the volute casing, the expansion coefficient of the rib structure, distance between the rib starting point and volute entrance, and radius of the volute entrance, were selected as geometric parameters. The results of parametric study show that performance parameters are significantly affected by both the geometric variables and operating conditions. Some configurations of the double volute casing showed outstanding performance in terms of the efficiency and radial thrust coefficient.

  7. Effects of blade thickness on performance of axial flow pump and analysis of internal flow field%叶片厚度对轴流泵性能影响及内部流场分析

    Institute of Scientific and Technical Information of China (English)

    沙毅; 侯丽艳

    2012-01-01

    In order to investigate the variable-thickness performance of blade in a axial flow pump, a QY90-4.4-1.5 submersible axial flow pump with specific speed 550 and rotate velocity 2900 r/min, especially its particular impeller and guide vane has been designed on the basis of arc method and streamline method. Based on experiments with increasing in leaf thickness, the reason about the difference among curves of qv-H, qv-P, qv-tj were studied. The three-dimensional internal flow with effect of impeller blade thickness within axial flow has been numerically simulated by CFD, both the relative velocity distribution on the optimal condition and static pressure distribution on the different condition of blade surface were obtained. It can be revealed that pump performance with thin blade was improved, but the anti-cavitation was reduced. It also can be showed that the situations of flow separation, backflow and secondary flow were more serious for the thick blades, which were the main reasons for the low efficiency of pump.%为研究叶片厚度对轴流泵性能影响及其内部流场变化规律,该文采用圆弧法和流线法进行比转速550、转速2 900 r/min的QY90-4.4-1.5型潜水轴流泵水力模型设计,完成产品开发及样机型式试验.通过加厚叶轮叶片进行对比试验,阐明泵流量—扬程、流量—轴功率和流量—效率曲线产生差别的原因.采用计算流体动力学(CFD)方法进行叶片厚度对流场影响的数值计算,得到最优工况叶片表面相对速度分布和不同工况叶片表面静压分布.经过分析,阐明薄叶片总体性能优于厚叶片,但抗汽蚀性能可能劣于厚叶片.厚叶片翼型脱流、叶片进出口出现回流及二次流情况更为严重,水力损失较大,是泵效率等性能参数偏低的主要原因.

  8. Experimental studies of pedestrian flows under different boundary conditions

    CERN Document Server

    Zhang, Jun

    2015-01-01

    In this article the dynamics of pedestrian streams in four different scenarios are compared empirically to investigate the influence of boundary conditions on it. The Voronoi method, which allows high resolution and small fluctuations of measured density in time and space, is used to analyze the experiments. It is found that pedestrian movement in systems with different boundary conditions (open, periodic boundary conditions and outflow restrained) presents various characteristics especially when the density is larger than 2 m-2. In open corridor systems the specific flow increases continuously with increasing density till 4 m-2. The specific flow keeps constant in systems with restrained outflow, whereas it decreases from 1 (m.s)-1 to zero in system with closed periodical condition.

  9. Eddy Current Minimizing Flow Plug for Use in Flow Conditioning and Flow Metering

    Science.gov (United States)

    England, John Dwight (Inventor); Kelley, Anthony R. (Inventor)

    2015-01-01

    An eddy-current-minimizing flow plug has open flow channels formed between the plug's inlet and outlet. Each open flow channel includes (i) a first portion that originates at the inlet face and converges to a location within the plug that is downstream of the inlet, and (ii) a second portion that originates within the plug and diverges to the outlet. The diverging second portion is approximately twice the length of the converging first portion. The plug is devoid of planar surface regions at its inlet and outlet, and in fluid flow planes of the plug that are perpendicular to the given direction of a fluid flowing therethrough.

  10. A Magnetically Coupled Cryogenic Pump

    Science.gov (United States)

    Hatfield, Walter; Jumper, Kevin

    2011-01-01

    Historically, cryogenic pumps used for propellant loading at Kennedy Space Center (KSC) and other NASA Centers have a bellows mechanical seal and oil bath ball bearings, both of which can be problematic and require high maintenance. Because of the extremely low temperatures, the mechanical seals are made of special materials and design, have wearing surfaces, are subject to improper installation, and commonly are a potential leak path. The ball bearings are non-precision bearings [ABEC-1 (Annular Bearing Engineering Council)] and are lubricated using LOX compatible oil. This oil is compatible with the propellant to prevent explosions, but does not have good lubricating properties. Due to the poor lubricity, it has been a goal of the KSC cryogenics community for the last 15 years to develop a magnetically coupled pump, which would eliminate these two potential issues. A number of projects have been attempted, but none of the pumps was a success. An off-the-shelf magnetically coupled pump (typically used with corrosive fluids) was procured that has been used for hypergolic service at KSC. The KSC Cryogenics Test Lab (CTL) operated the pump in cryogenic LN2 as received to determine a baseline for modifications required. The pump bushing, bearings, and thrust rings failed, and the pump would not flow liquid (this is a typical failure mode that was experienced in the previous attempts). Using the knowledge gained over the years designing and building cryogenic pumps, the CTL determined alternative materials that would be suitable for use under the pump design conditions. The CTL procured alternative materials for the bearings (bronze, aluminum bronze, and glass filled PTFE) and machined new bearing bushings, sleeves, and thrust rings. The designed clearances among the bushings, sleeves, thrust rings, case, and case cover were altered once again using experience gained from previous cryogenic pump rebuilds and designs. The alternative material parts were assembled into

  11. HeartWare third-generation implantable continuous flow pump as biventricular support: mid-term follow-up.

    Science.gov (United States)

    Loforte, Antonio; Monica, Paola Lilla Della; Montalto, Andrea; Musumeci, Francesco

    2011-03-01

    A long-term mechanical biventricular support by HeartWare HVAS third-generation continuous flow pump (HeartWare, Inc, Miramar, FL, USA) was implanted in a Korean patient with a small chest size for treatment of a refractory end-stage heart failure due to an idiopathic dilative cardiomyopathy. We report our experience with a single patient and the early mid-term follow-up results with such a mechanical ventricular support.

  12. Critical conditions of bed sediment entrainment due to debris flow

    Directory of Open Access Journals (Sweden)

    M. Papa

    2004-01-01

    Full Text Available The present study describes entrainment characteristics of bed material into debris flow, based on flume tests, numerical and dimensional analyses. Flume tests are conducted to investigate influences of bed sediment size on erosion rate by supplying debris flows having unsaturated sediment concentration over erodible beds. Experimental results show that the erosion rate decreases monotonically with increase of sediment size, although erosion rate changes with sediment concentration of debris flow body. In order to evaluate critical condition of bed sediment entrainment, a length scale which measures an effective bed shear stress is introduced. The effective bed shear stress is defined as total shear stress minus yield stress on the bed surface. The results show that critical entrainment conditions can be evaluated well in terms of Shields curve using the effective bed shear stress instead of a usual bed shear stress.

  13. A Boundary Condition for Simulation of Flow Over Porous Surfaces

    Science.gov (United States)

    Frink, Neal T.; Bonhaus, Daryl L.; Vatsa, Veer N.; Bauer, Steven X. S.; Tinetti, Ana F.

    2001-01-01

    A new boundary condition is presented.for simulating the flow over passively porous surfaces. The model builds on the prior work of R.H. Bush to eliminate the need for constructing grid within an underlying plenum, thereby simplifying the numerical modeling of passively porous flow control systems and reducing computation cost. Code experts.for two structured-grid.flow solvers, TLNS3D and CFL3D. and one unstructured solver, USM3Dns, collaborated with an experimental porosity expert to develop the model and implement it into their respective codes. Results presented,for the three codes on a slender forebody with circumferential porosity and a wing with leading-edge porosity demonstrate a good agreement with experimental data and a remarkable ability to predict the aggregate aerodynamic effects of surface porosity with a simple boundary condition.

  14. Pumping machinery theory and practice

    CERN Document Server

    Badr, Hassan M

    2014-01-01

    Pumping Machinery Theory and Practice comprehensively covers the theoretical foundation and applications of pumping machinery. Key features: Covers characteristics of centrifugal pumps, axial flow pumps and displacement pumpsConsiders pumping machinery performance and operational-type problemsCovers advanced topics in pumping machinery including multiphase flow principles, and two and three-phase flow pumping systemsCovers different methods of flow rate control and relevance to machine efficiency and energy consumptionCovers different methods of flow rate control and relevance to machine effi

  15. Heat Flow for the Minimal Surface with Plateau Boundary Condition

    Institute of Scientific and Technical Information of China (English)

    Kung Ching CHANG; Jia Quan LIU

    2003-01-01

    The heat flow for the minimal surface under Plateau boundary condition is defined to be aparabolic variational inequality, and then the existence, uniqueness, regularity, continuous dependenceon the initial data and the asymptotics are studied. It is applied as a deformation of the level sets inthe critical point theory.

  16. 叶片包角对离心泵流动诱导振动噪声的影响%Effects of vane wrap angle on flow induced vibration and noise of centrifugal pumps

    Institute of Scientific and Technical Information of China (English)

    王勇; 刘厚林; 刘东喜; 王健; 吴贤芳

    2013-01-01

    In order to better understand the effects of vane wrap angle on flow induced vibration and noise of centrifugal pumps, a single grade end suction centrifugal pump is chosen as research object. The vane wrap angle was varied from 115°to 110°, 120°and 125°, while the volute and other geometric parameters were kept constant. The vibration and noise signal of the model pump were acquired via PXI-4472B dynamic data acquisition system developed by NI Company in United States and measured respectively by the 4 acceleration transducers MA352A60 made in the PBC Company in USA with a range of 5-70 kHz, and one hydrophone with a range of 50-70 kHz and a received sound pressure sensitivity of -204 dB. The hydrophone measure point was located in pump outlet pipe and the 4 acceleration transducers were placed on the suction flange a1, discharge flange a2, the pump casing a3 and the pump foot a4 respectively. Based on the pump testing system and the virtual instrument data acquisition system, the pump flow-induced vibration and noise testing system was established, which realized the synchronous collection of the pump characteristics and the vibration and noise signal. In addition, the system improved testing accuracy. On the centrifugal pump closed experimental rig, the performance characteristics (flow-head curves and flow-efficiency curves), the flow-induced vibration and noise signals of model pump with different vane wrap angle in the full flow range were measured and analyzed. Experimental results show that there was an optimal value of vane wrap angle for pump to obtain maximum efficiency under design condition, because the unsteady flow (take-off flow and vortex) decreased with the increase of vane wrap angle, but the blade length growth, friction loss increased. 115°was found as the optimal vane wrap angle for the model pump in this investigation. The vibration intensity of model pump with different vane wrap angle at four measurement points was nearly unchanged or

  17. 基于CFD的轴流泵空化特性预测%Prediction of cavitation performance of axial-flow pump based on CFD

    Institute of Scientific and Technical Information of China (English)

    杨正军; 王福军; 刘竹青; 张志民

    2011-01-01

    基于空泡动力学和汽液两相流理论,应用计算流体动力学(CFD)技术模拟了轴流泵在不同进口压力条件下(包含轴流泵中未发生空化和发生剧烈空化的多种情况)的流场,研究了随着空化发生、发展速度场及压力场变化过程,并对轴流泵能量特性、空化性能进行了预测.结果表明,在非空化条件下,CFD计算可较准确地预测水泵扬程等能量特性,预测值与试验值相差在2%以内;在空化条件下,CFD计算成功地捕获到了空化发生、发展过程;流场中空化发生直接影'响叶轮叶片上的压力分布,进而影响水泵的扬程、轴功率等外特性;在发生空化条件下,导叶背面进水边靠近轮缘位置也会出现空化现象;在叶轮各个通道内空化区域分布相似,轴对称性明显,而导叶体内各个通道的空化区域分布差异大,呈明显的非轴对称分布,该非轴对称性的空化区域也是空化造成轴流泵不稳定运行的一个因素.%The flow field in an axial-flow pump at different inlet pressure conditions including cavitating and non-cavitating conditions was simulated by using the computational fluid dynamics (CFD) approach based on theory of bubble dynamics and steam-liquid two-phase flow. The velocity field and pressure distribution were analysed during cavitation progress and the pump characteristics were predicted. The results show that under the non-cavitating condition, the pump head-flow relationship is well predicted with an inaccuracy within 2%. While under the cavitating condition, the cavitation occurring and developing processes are captured successfully by CFD simulation. The cavitation directly affects the pressure distribution on impeller blade surfaces, and also results in change of the pump head and power characteristics. Under the cavitation condition, the cavitation area can be found at the leading edge of the guide vane suction sides. Similarity of the cavitation distribution are

  18. Effects of changes in pumping on regional groundwater-flow paths, 2005 and 2010, and areas contributing recharge to discharging wells, 1990–2010, in the vicinity of North Penn Area 7 Superfund site, Montgomery County, Pennsylvania

    Science.gov (United States)

    Senior, Lisa A.; Goode, Daniel J.

    2017-06-06

    A previously developed regional groundwater flow model was used to simulate the effects of changes in pumping rates on groundwater-flow paths and extent of recharge discharging to wells for a contaminated fractured bedrock aquifer in southeastern Pennsylvania. Groundwater in the vicinity of the North Penn Area 7 Superfund site, Montgomery County, Pennsylvania, was found to be contaminated with organic compounds, such as trichloroethylene (TCE), in 1979. At the time contamination was discovered, groundwater from the underlying fractured bedrock (shale) aquifer was the main source of supply for public drinking water and industrial use. As part of technical support to the U.S. Environmental Protection Agency (EPA) during the Remedial Investigation of the North Penn Area 7 Superfund site from 2000 to 2005, the U.S. Geological Survey (USGS) developed a model of regional groundwater flow to describe changes in groundwater flow and contaminant directions as a result of changes in pumping. Subsequently, large decreases in TCE concentrations (as much as 400 micrograms per liter) were measured in groundwater samples collected by the EPA from selected wells in 2010 compared to 2005‒06 concentrations.To provide insight on the fate of potentially contaminated groundwater during the period of generally decreasing pumping rates from 1990 to 2010, steady-state simulations were run using the previously developed groundwater-flow model for two conditions prior to extensive remediation, 1990 and 2000, two conditions subsequent to some remediation 2005 and 2010, and a No Pumping case, representing pre-development or cessation of pumping conditions. The model was used to (1) quantify the amount of recharge, including potentially contaminated recharge from sources near the land surface, that discharged to wells or streams and (2) delineate the areas contributing recharge that discharged to wells or streams for the five conditions.In all simulations, groundwater divides differed from

  19. Experimental study of choking flow of water at supercritical conditions

    Science.gov (United States)

    Muftuoglu, Altan

    Future nuclear reactors will operate at a coolant pressure close to 25 MPa and at outlet temperatures ranging from 500°C to 625°C. As a result, the outlet flow enthalpy in future Supercritical Water-Cooled Reactors (SCWR) will be much higher than those of actual ones which can increase overall nuclear plant efficiencies up to 48%. However, under such flow conditions, the thermal-hydraulic behavior of supercritical water is not fully known, e.g., pressure drop, forced convection and heat transfer deterioration, critical and blowdown flow rate, etc. Up to now, only a very limited number of studies have been performed under supercritical conditions. Moreover, these studies are conducted at conditions that are not representative of future SCWRs. In addition, existing choked flow data have been collected from experiments at atmospheric discharge pressure conditions and in most cases by using working fluids different than water which constrain researchers to analyze the data correctly. In particular, the knowledge of critical (choked) discharge of supercritical fluids is mandatory to perform nuclear reactor safety analyses and to design key mechanical components (e.g., control and safety relief valves, etc.). Hence, an experimental supercritical water facility has been built at Ecole Polytechnique de Montreal which allows researchers to perform choking flow experiments under supercritical conditions. The facility can also be used to carry out heat transfer and pressure drop experiments under supercritical conditions. In this thesis, we present the results obtained at this facility using a test section that contains a 1 mm inside diameter, 3.17 mm long orifice plate with sharp edges. Thus, 545 choking flow of water data points are obtained under supercritical conditions for flow pressures ranging from 22.1 MPa to 32.1 MPa, flow temperatures ranging from 50°C to 502°C and for discharge pressures from 0.1 MPa to 3.6 MPa. Obtained data are compared with the data given in

  20. Impacts of Snowy Weather Conditions on Expressway Traffic Flow Characteristics

    Directory of Open Access Journals (Sweden)

    Jiancheng Weng

    2013-01-01

    Full Text Available Snowy weather will significantly degrade expressway operations, reduce service levels, and increase driving difficulty. Furthermore, the impact of snow varies in different types of roads, diverse cities, and snow densities due to different driving behavior. Traffic flow parameters are essential to decide what should be appropriate for weather-related traffic management and control strategies. This paper takes Beijing as a case study and analyzes traffic flow data collected by detectors in expressways. By comparing the performance of traffic flow under normal and snowy weather conditions, this paper quantitatively describes the impact of adverse weather on expressway volume and average speeds. Results indicate that average speeds on the Beijing expressway under heavy snow conditions decrease by 10–20 km/h when compared to those under normal weather conditions, the vehicle headway generally increases by 2–4 seconds, and the road capacity drops by about 33%. This paper also develops a specific expressway traffic parameter reduction model which proposes reduction coefficients of expressway volumes and speeds under various snow density conditions in Beijing. The conclusions paper provide effective foundational parameters for urban expressway controls and traffic management under snow conditions.

  1. Measurement of the gas-flow reduction factor of the KATRIN DPS2-F differential pumping section

    CERN Document Server

    Lukic, S; Bornschein, L; Drexlin, G; Kosmider, A; Schloesser, K; Windberger, A

    2011-01-01

    We determined the gas-flow reduction factor of the second forward Differential Pumping Section (DPS2-F) for the KATRIN experiment using a dedicated vacuum-measurement setup and by detailed molecular-flow simulation of the DPS2-F beam tube and of the measurement apparatus. In the measurement, non-radioactive test gases deuterium, helium, neon, argon and krypton were used, the input gas flow was provided by a commercial mass-flow controller, and the output flow was measured using a residual gas analyzer, in order to distinguish it from the outgassing background. The measured reduction factor with the empty beam tube at room temperature for gases with mass 4 is 1.8(4)E4, which is in excellent agreement with the simulated value of 1.6E4. The simulated reduction factor for tritium, based on the interpolated value for the turbo-molecular pump capture factor is 2.5E4. The difference with respect to the design value of 1E5 is due to the odifications in the beam tube geometry since the initial design, and can be partl...

  2. Fluid dynamics in airway bifurcations: III. Localized flow conditions.

    Science.gov (United States)

    Martonen, T B; Guan, X; Schreck, R M

    2001-04-01

    Localized flow conditions (e.g., backflows) in transition regions between parent and daughter airways of bifurcations were investigated using a computational fluid dynamics software code (FIDAP) with a Cray T90 supercomputer. The configurations of the bifurcations were based on Schreck s (1972) laboratory models. The flow intensities and spatial regions of reversed motion were simulated for different conditions. The effects of inlet velocity profiles, Reynolds numbers, and dimensions and orientations of airways were addressed. The computational results showed that backflow was increased for parabolic inlet conditions, larger Reynolds numbers, and larger daughter-to-parent diameter ratios. This article is the third in a systematic series addressed in this issue; the first addressed primary velocity patterns and the second discussed secondary currents.

  3. Characteristics of Gas Flow within a Micro Diffuser/Nozzle Pump

    Institute of Scientific and Technical Information of China (English)

    LI Xiu-Han; YU Xiao-Mei; ZHANG Da-Cheng; CUI Hai-Hang; LI Ting; WANG Ying; WANG Yang-Yuan

    2006-01-01

    @@ The gas flow characteristics for various shapes of micro diffuser/nozzles have been experimentally investigated.The micro diffuser/nozzles with the lengths of 70μm, 90μm, 125μm and the taper angles of 7°, 10°, 14° are designed and fabricated based on silicon micromachining technology for optimizing and comparing. The flat-wall diffuser/nozzle is 40 μm× 5μm in depth and width. An experimental setup is designed to measure the gas flow rates under controlled temperature and pressure condition. Optimized values for the taper angle and the length of the diffuser/nozzle are experimentally obtained.

  4. Flow reversal at low voltage and low frequency in a microfabricated ac electrokinetic pump

    DEFF Research Database (Denmark)

    Gregersen, Misha Marie; Olesen, Laurits Højgaard; Brask, Anders

    2007-01-01

    Microfluidic chips have been fabricated in Pyrex glass to study electrokinetic pumping generated by a low-voltage ac bias applied to an in-channel asymmetric metallic electrode array. A measurement procedure has been established and followed carefully resulting in a high degree of reproducibility...... of the measurements over several days. A large coverage fraction of the electrode array in the microfluidic channels has led to an increased sensitivity allowing for pumping measurements at low bias voltages. Depending on the ionic concentration a hitherto unobserved reversal of the pumping direction has been...

  5. Valveless pumping mechanics of the embryonic heart during cardiac looping: Pressure and flow through micro-PIV.

    Science.gov (United States)

    Bark, D L; Johnson, B; Garrity, D; Dasi, L P

    2017-01-04

    Cardiovascular development is influenced by the flow-induced stress environment originating from cardiac biomechanics. To characterize the stress environment, it is necessary to quantify flow and pressure. Here, we quantify the flow field in a developing zebrafish heart during the looping stage through micro-particle imaging velocimetry and by analyzing spatiotemporal plots. We further build upon previous methods to noninvasively quantify the pressure field at a low Reynolds number using flow field data for the first time, while also comparing the impact of viscosity models. Through this method, we show that the atrium builds up pressure to ~0.25mmHg relative to the ventricle during atrial systole and that atrial expansion creates a pressure difference of ~0.15mmHg across the atrium, resulting in efficient cardiac pumping. With these techniques, it is possible to noninvasively fully characterize hemodynamics during heart development.

  6. Stokes Flow with Slip and Kuwabara Boundary Conditions

    Indian Academy of Sciences (India)

    Sunil Datta; Satya Deo

    2002-08-01

    The forces experienced by randomly and homogeneously distributed parallel circular cylinder or spheres in uniform viscous flow are investigated with slip boundary condition under Stokes approximation using particle-in-cell model technique and the result compared with the no-slip case. The corresponding problem of streaming flow past spheroidal particles departing but little in shape from a sphere is also investigated. The explicit expression for the stream function is obtained to the first order in the small parameter characterizing the deformation. As a particular case of this we considered an oblate spheroid and evaluate the drag on it.

  7. Analysis on flow field of the valveless piezoelectric pump with two inlets and one outlet and a rotating unsymmetrical slopes element

    Science.gov (United States)

    Xia, Qixiao; Zhang, Jianhui; Lei, Hong; Cheng, Wei

    2012-05-01

    Typically, liquid pump and liquids mixer are two separate devices. The invention of piezoelectric pump makes it possible to integrate the two devices. Hower, the existing piezoelectric mixing-pumps are larger because the need the space outside the chamber, and another shortcome of them is that they cannot adjust the mixing ratio of two liquids. In this paper, a new piezoelectric pump being capable of integrating mixer and pump is presented, based on the theory of the piezoelectric pump with the unsymmetrical slopes element (USE). Besides the features of two inlets and one outlet, the piezoelectric pump has a rotatable unsymmetrical slopes element(RUSE). When the pump works, two fluids flow into the inlet channels respectively. Then the RUSE controls the ratio of the two flows by adjusting the flow resistances of the two inlet channels. The fluids form a net flow due to the USE principle, while they are mixed into a homogeneous solution due to strong turbulence flow field and complex vortices generated by RUSE in the chamber. And then the solution flows through the outlet. Firstly, the theoretical analysis on this pump is performed. Meanwhile, the flow field in the chamber is calculated and simulated. And then, the relationship between the flows of the two channels and the rotating angle of the RUSE is set up and analyzed. Finally, experiment with the proposed pump is carried out to verify the numerical results. A RUSE with 20° slope angle is used in the experiment. Four sets of data are tested with the RUSE at the rotating angles of 0°, 6°, 11°, and 16°, respectively, corresponding to the numerical models. The experimental results show that the empirical data and the theoretical data share the same trend. The maximum error between the theoretical flow and the experimental flow is 11.14%, and the maximum error between the theoretical flow ratio of the two inlets and the experimental one is 2.5%. The experiment verified the theoretical analysis. The proposed

  8. Finite time exergoeconomic performance optimization for an irreversible universal steady flow variable-temperature heat reservoir heat pump cycle model

    Directory of Open Access Journals (Sweden)

    Huijun Feng, Lingen Chen, Fengrui Sun

    2010-11-01

    Full Text Available An irreversible universal steady flow heat pump cycle model with variable-temperature heat reservoirs and the losses of heat-resistance and internal irreversibility is established by using the theory of finite time thermodynamics. The universal heat pump cycle model consists of two heat-absorbing branches, two heat-releasing branches and two adiabatic branches. Expressions of heating load, coefficient of performance (COP and profit rate of the universal heat pump cycle model are derived, respectively. By means of numerical calculations, heat conductance distributions between hot- and cold-side heat exchangers are optimized by taking the maximum profit rate as objective. There exist an optimal heat conductance distribution and an optimal thermal capacity rate matching between the working fluid and heat reservoirs which lead to a double maximum profit rate. The effects of internal irreversibility, total heat exchanger inventory, thermal capacity rate of the working fluid and heat capacity ratio of the heat reservoirs on the optimal finite time exergoeconomic performance of the cycle are discussed in detail. The results obtained herein include the optimal finite time exergoeconomic performances of endoreversible and irreversible, constant- and variable-temperature heat reservoir Brayton, Otto, Diesel, Atkinson, Dual, Miller and Carnot heat pump cycles.

  9. Results of Investigations of Failures of Geothermal Direct Use Well Pumps

    Energy Technology Data Exchange (ETDEWEB)

    Culver, G.

    1994-12-01

    Failures of 13 geothermal direct-use well pumps were investigated and information obtained about an additional 5 pumps that have been in service up to 23 years, but have not failed. Pumps with extra long lateral and variable-speed drives had the highest correlation with reduced time in service. There appears to be at least circumstantial evidence that recirculation may be a cause of reduced pump life. If recirculation is a cause of pump failures, pump specifiers will need to be more aware of minimum flow conditions as well as maximum flow conditions when specifying pumps. Over-sizing pumps and the tendency to specify pumps with high flow and low Net Positive Suction Head (NPSH) could lead to increased problems with recirculation.

  10. Results of investigations of failures of geothermal direct-use well pumps

    Energy Technology Data Exchange (ETDEWEB)

    Culver, G.

    1994-12-01

    Failures of 13 geothermal direct-use well pumps were investigated and information obtained about an additional 5 pumps that have been in service up to 23 years, but have not failed. Pumps with extra long lateral and variable-speed drives had the highest correlation with reduced time in service. There appears to be at least circumstantial evidence that recirculation may be a cause of reduced pump life. If recirculation is a cause of pump failures, pump specifiers will need to be more aware of minimum flow conditions as well as maximum flow conditions when specifying pumps. Over-sizing pumps and the tendency to specify pumps with high flow and low Net Positive Suction Head (NPSH) could lead to increased problems with recirculation.

  11. Numerical simulation on cavitating characteristic in impeller of axial-flow pump%轴流泵叶轮区域空化特性数值模拟

    Institute of Scientific and Technical Information of China (English)

    施卫东; 李通通; 张德胜; 王国涛; 周岭

    2012-01-01

    In order to study the internal cavitation characteristic of axial flow pump, the steady turbulent flow field of an axial flow pump(ns=1033) at different conditions was simulated by using standard K-Ε turbulence model, RNG K-Ε turbulence model, K-Ω turbulence model, SST K-Ω turbulence model and homogeneous multiphase model based on ANSYS CFX software. The numerical results were compared with the experiment values to verify the adaptability of the different turbulent models and multiphase model, and to study the cavitation characteristics of the impeller region. The results showed that the K-E turbulence model has better accuracy than the other three turbulent models in simulation, predictive errors of critical NPSHc is 6.32%,which can reflect the internal cavitation characteristic of the axial flow pump well. With the decrease of the NPSH, along the flow direction, vapor first occurred on the leading edge of the blade close to the tip, and then developed to the middle area of the blades until to the whole passage. On the critical cavitation condition, the vapor area of the middle side along the radical direction of the blade is large. When the cavitation is serious, the streamline at the back of the blade's suction side is disorder and generate the vortex micro group, which will flow from the hub to the shroud of the impeller, cause the distribution of axial flow velocity at the outlet of the impeller inhomogeneous, and increase the disturbulence of the flow field in impeller region. These phenomena reveal the cavitation characteristics of the axial-flow pump.%为了研究轴流泵内部叶轮区域空化特性,该文基于ANSYS CFX软件,分别应用Standardκ-ε,RNG κ-ε,κ-ω和SSTκ-ω湍流模型、均质多相流模型,对比转数ns=1033轴流泵在不同工况下进行全流道数值计算,将模拟值与试验结果进行对比分析,验证不同湍流模型及多相流模型的适应性并探究叶轮区域的空化特性.结果表明:在设计工

  12. Stalled-Flow and Head-Loss Model for Diffuser Pumps

    Science.gov (United States)

    Meng, S. Y.

    1984-01-01

    Modeling procedure approximates inlet transition zone (blade leading edge to blade throat) of diffuser pump as two-dimensional cascade, properties of which are well known. Model applied to stators as well as rotors. Procedure much faster than previous methods.

  13. Stalled-Flow and Head-Loss Model for Diffuser Pumps

    Science.gov (United States)

    Meng, S. Y.

    1984-01-01

    Modeling procedure approximates inlet transition zone (blade leading edge to blade throat) of diffuser pump as two-dimensional cascade, properties of which are well known. Model applied to stators as well as rotors. Procedure much faster than previous methods.

  14. 叶片泵/轴向柱塞泵的压力与流量性能测试%Pressure-flow Test Experiment of Vane Pump and Axial Piston Pump

    Institute of Scientific and Technical Information of China (English)

    张志森

    2015-01-01

    Pressure⁃flow test experiments for vane pump and axial piston pump on the hydraulic experiment platform were made. The equations for flow rate, volumetric efficiency and overall efficiency of hydraulic pump were built. The flow rate data of the throttle valve when hydraulic pump in different outlet pressure were collected, the pressure⁃flow characteristic curves were drawn by using MATLAB software, and contrastive analysis to pressure⁃flow characteristic of two kinds of pump was made.%对液压实验平台液压泵站上的叶片泵/轴向柱塞泵进行压力-流量测试实验,建立液压泵的流量、容积效率及总效率方程,采集液压泵在不同出口压力下通过其节流阀的流量大小,并应用MATLAB软件绘制出压力-流量特性曲线,对比分析两种液压泵在实验测试过程中,其压力-流量特性变化情况。

  15. Estimation of overland flow metrics at semiarid condition: Patagonian Monte

    Directory of Open Access Journals (Sweden)

    M. J. Rossi

    2012-05-01

    Full Text Available Water infiltration and overland flow (WIOF processes are relevant in considering water partition among plant life forms, the sustainability of vegetation and the design of sustainable hydrological management. WIOF processes in arid and semiarid regions present regional characteristic trends imposed by the prevailing physical conditions of the upper soil as evolved under water-limited climate. A set of plot-scale field experiments at the semi-arid Patagonian Monte (Argentina was performed in order to estimate infiltration-overland descriptive flow parameters. The micro-relief of undisturbed field plots at z-scale <1 mm was characterized through close-range stereo-photogrammetry and geo-statistical modelling. The overland flow areas produced by experimental runoff events were video-recorded and the runoff speed was measured with ortho-image processing software. Antecedent and post-inflow moisture were measured, and texture, bulk density and physical properties of the soil at the upper vadose zone were estimated. Field data were used to calibrate a physically-based, time explicit model of water balance in the upper soil and overland flows with a modified Green-Ampt (infiltration and Chezy's (overland flow algorithms. Modelling results satisfy validation criteria based on the observed overland flow areas, runoff-speed, water mass balance of the upper vadose zone, infiltration depth, slope along runoff-plume direction, and depression storage intensity. The experimental procedure presented supplies plot-scale estimates of overland flow and infiltration intensities at various intensities of water input which can be incorporated in larger-scale hydrological grid-models of arid regions. Findings were: (1 Overland flow velocities as well as infiltration-overland flow mass balances are consistently modelled by considering variable infiltration rates corresponding to depression storage and/or non-ponded areas. (2 The statistical relations presented

  16. SAP FLOW RESPONSE OF CHERRY TREES TO WEATHER CONDITION

    Directory of Open Access Journals (Sweden)

    Á. JUHÁSZ

    2011-03-01

    Full Text Available Sap flow response of cherry trees to weather condition. Themain goal of our study is to measure water-demand of cherry trees budded ontodifferent rootstocks by sapflow equipment and to study the sap flow response to themeteorological factors. The investigations are carried out in Soroksár in Hungary at‘Rita’ sweet cherry orchard. The pattern of sapflow was analyzed in relation ofsolar radiation, vapour pressure deficit and air temperature. Between solar radiationand sap flow was found a parabolic relation, daily pattern of sapflow is in closerelation (cubic also to vapour pressure deficit. No significant relationship existedbetween sapflow and air temperature. The sapflow performance of sweet cherrytrees on different rootstocks showed typical daily characters.

  17. LOW FLOW PULSE PROPERTY OF HELICAL GEAR PUMP%斜齿齿轮泵小脉动输出特性

    Institute of Scientific and Technical Information of China (English)

    周骥平; 姜铭; 李益民; 殷金祥; 姚如一

    2000-01-01

    The relationship of the helical gear pump flow puls e with screw angle, tooth broad and other parameters is analyzed and the conclus ion that under the same main parameters the flow pulse of helical gear pump is lower than that of spur gear pump is achieved.%分析了斜齿齿轮泵的流量脉动与螺旋角β、齿宽b等参数的 关系,得出主要参数相同的斜齿齿轮泵的流量脉动小于直齿齿轮泵的结论。

  18. Optimization analysis of high temperature heat pump coupling to desiccant wheel air conditioning system

    DEFF Research Database (Denmark)

    Sheng, Ying; Zhang, Yufeng; Fang, Lei

    2014-01-01

    The high temperature heat pump and desiccant wheel (HTHP&DW) system can make full use of heat released from the condenser of heat pump for DW regeneration without additional heat. In this study, DW operation in the HTHP&DW system was investigated experimentally, and the optimization analysis....... Compared to the isosteric heat, heat accumulation in the desiccant and matrix material and heat leakage from regeneration side to process side have greater influence on the adiabatic effectiveness. Higher regeneration temperature leads to lower adiabatic effectiveness that increases more cooling load...

  19. Empirical Platform Data Analysis to Investigate how Heat Pumps Operate in Real-Life Conditions

    DEFF Research Database (Denmark)

    Carmo, Carolina; Elmegaard, Brian; Nielsen, Mads Pagh

    2015-01-01

    Heat pumps have been widely acknowledged, by academia and industry, as highly efficient thermal energy technologies, for space heating and domestic hot water production. However, there is a lack of information about real performance in residential single family houses with active participation...... heat pump configurations are considered depending on source (ground or air) and sink (radiators, floor heating and/or combined systems). This unique study intends to point out the benefits and limitations of such technologies in terms of energy efficiency and comfort delivery, as well as investigating...

  20. A Conductivity Relationship for Steady-state Unsaturated Flow Processes under Optimal Flow Conditions

    Energy Technology Data Exchange (ETDEWEB)

    Liu, H. H.

    2010-09-15

    Optimality principles have been used for investigating physical processes in different areas. This work attempts to apply an optimal principle (that water flow resistance is minimized on global scale) to steady-state unsaturated flow processes. Based on the calculus of variations, we show that under optimal conditions, hydraulic conductivity for steady-state unsaturated flow is proportional to a power function of the magnitude of water flux. This relationship is consistent with an intuitive expectation that for an optimal water flow system, locations where relatively large water fluxes occur should correspond to relatively small resistance (or large conductance). Similar results were also obtained for hydraulic structures in river basins and tree leaves, as reported in other studies. Consistence of this theoretical result with observed fingering-flow behavior in unsaturated soils and an existing model is also demonstrated.

  1. Simulations of a Liquid Hydrogen Inducer at Low-Flow Off-Design Flow Conditions

    Science.gov (United States)

    Hosangadi, A.; Ahuja, V.; Ungewitter, R. J.

    2005-01-01

    The ability to accurately model details of inlet back flow for inducers operating a t low-flow, off-design conditions is evaluated. A sub-scale version of a three-bladed liquid hydrogen inducer tested in water with detailed velocity and pressure measurements is used as a numerical test bed. Under low-flow, off-design conditions the length of the separation zone as well as the swirl velocity magnitude was under predicted with a standard k-E model. When the turbulent viscosity coefficient was reduced good comparison was obtained a t all the flow conditions examined with both the magnitude and shape of the profile matching well with the experimental data taken half a diameter upstream of the leading edge. The velocity profiles and incidence angles a t the leading edge itself were less sensitive to the back flow length predictions indicating that single-phase performance predictions may be well predicted even if the details of flow separation modeled are incorrect. However, for cavitating flow situations the prediction of the correct swirl in the back flow and the pressure depression in the core becomes critical since it leads to vapor formation. The simulations have been performed using the CRUNCH CFD(Registered Trademark) code that has a generalized multi-element unstructured framework and a n advanced multi-phase formulation for cryogenic fluids. The framework has been validated rigorously for predictions of temperature and pressure depression in cryogenic fluid cavities and has also been shown to predict the cavitation breakdown point for inducers a t design conditions.

  2. Commercialization of air conditioning heat pump/water heater. Final technical report, Volume 2: Appendix A through E

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1996-01-30

    This is the final technical report on a commercialization project for an air conditioning heat pump water heater. The objective of the project was to produce a saleable system which would be economically competitive with natural gas and cost effective with regard to initial cost versus annual operating costs. The development and commercialization of the system is described. Compiled data included in numerous figures, tables and graphs.

  3. Ferroelectric Pump

    Science.gov (United States)

    Jalink, Antony, Jr. (Inventor); Hellbaum, Richard F. (Inventor); Rohrbach, Wayne W. (Inventor)

    2000-01-01

    A ferroelectric pump has one or more variable volume pumping chambers internal to a housing. Each chamber has at least one wall comprising a dome shaped internally prestressed ferroelectric actuator having a curvature and a dome height that varies with an electric voltage applied between an inside and outside surface of the actuator. A pumped medium flows into and out of each pumping chamber in response to displacement of the ferroelectric actuator. The ferroelectric actuator is mounted within each wall and isolates each ferroelectric actuator from the pumped medium, supplies a path for voltage to be applied to each ferroelectric actuator, and provides for positive containment of each ferroelectric actuator while allowing displacement of the entirety of each ferroelectric actuator in response to the applied voltage.

  4. Technical Subtopic 2.1: Modeling Variable Refrigerant Flow Heat Pump and Heat Recovery Equipment in EnergyPlus

    Energy Technology Data Exchange (ETDEWEB)

    Raustad, Richard; Nigusse, Bereket; Domitrovic, Ron

    2013-09-30

    The University of Central Florida/Florida Solar Energy Center, in cooperation with the Electric Power Research Institute and several variable-refrigerant-flow heat pump (VRF HP) manufacturers, provided a detailed computer model for a VRF HP system in the United States Department of Energy's (U.S. DOE) EnergyPlus? building energy simulation tool. Detailed laboratory testing and field demonstrations were performed to measure equipment performance and compare this performance to both the manufacturer's data and that predicted by the use of this new model through computer simulation. The project goal was to investigate the complex interactions of VRF HP systems from an HVAC system perspective, and explore the operational characteristics of this HVAC system type within a laboratory and real world building environment. Detailed laboratory testing of this advanced HVAC system provided invaluable performance information which does not currently exist in the form required for proper analysis and modeling. This information will also be useful for developing and/or supporting test standards for VRF HP systems. Field testing VRF HP systems also provided performance and operational information pertaining to installation, system configuration, and operational controls. Information collected from both laboratory and field tests were then used to create and validate the VRF HP system computer model which, in turn, provides architects, engineers, and building owners the confidence necessary to accurately and reliably perform building energy simulations. This new VRF HP model is available in the current public release version of DOE?s EnergyPlus software and can be used to investigate building energy use in both new and existing building stock. The general laboratory testing did not use the AHRI Standard 1230 test procedure and instead used an approach designed to measure the field installed full-load operating performance. This projects test methodology used the air

  5. Computational Cavitation Flows at Inception and Light Stages on an Axial-Flow Pump Blade and in a Cage-Guided Control Valve

    Institute of Scientific and Technical Information of China (English)

    Sumio SAITO; Masahiro SHIBATA; Hideo FUKAE; Eisuke OUTA

    2007-01-01

    Cavitation flows induced around an axial-flow pump blade and inside a high pressure cage-type valve are simulated by a two-dimensional unsteady Navier-Stokes analysis with the simplest treatment of bubble dynamics. The fluid is assumed as a continuum of homogeneous dispersed mixture of water and vapor nuclei. The analysis is aimed to capture transient stages with high amplitude pressure change during the birth and collapse of the bubble especially at the stage of cavitation inception. By the pump blade analysis, in which the field pressure is moderate,cavitation number of the inception and locations of developed cavitation are found to agree with experimental results in a wide flow range between high incidence and negative incidence. In the valve flow analysis, in which the water pressure of 5MPa is reduced to 2MPa, pressure change responding to the bubble collapse between the vapor pressure lower than 1 KPa and the extreme pressure of higher than 104 KPa is captured through a stable computation. Location of the inception bubble and pressure force to the valve plug is found agree well with the respective experimental features.

  6. Dynamics of AHL mediated quorum sensing under flow and non-flow conditions

    Science.gov (United States)

    Meyer, Andrea; Megerle, Judith A.; Kuttler, Christina; Müller, Johannes; Aguilar, Claudio; Eberl, Leo; Hense, Burkhard A.; Rädler, Joachim O.

    2012-04-01

    Quorum sensing (QS) describes the capability of microbes to communicate with each other by the aid of small molecules. Here we investigate the dynamics of QS-regulated gene expression induced by acylhomoserine lactones (AHLs) in Pseudomonas putida IsoF containing a green fluorescent protein-based AHL reporter. The fluorescence time course of individual colonies is monitored following the external addition of a defined AHL concentration to cells which had previously reached the QS-inactive state in AHL-free medium. Using a microfluidic setup the experiment is performed both under flow and non-flow conditions. We find that without supplying external AHL gene expression is induced without flow while flow suppresses the induction. Both without and with flow, at a low AHL concentration the fluorescence onset is significantly delayed while fluorescence starts to increase directly upon the addition of AHL at a high concentration. The differences between no flow and flow can be accounted for using a two-compartment model. This indicates AHL accumulation in a volume which is not affected by the flow. The experiments furthermore show significant cell-to-cell and colony-to-colony variability which is discussed in the context of a compartmentalized QS mechanism.

  7. Multi-point optimization on the diffuser of an axial flow pump

    Science.gov (United States)

    Yan, P.; Chen, T.; Wu, D. Z.; Wang, L. Q.

    2013-12-01

    For many pump applications, it is necessary to satisfy the performance requirements in more than one operating point. The conventional single-point design method which would cause a sharp decrease in the off-design point cannot fully meet such requirement. In this paper, an approach of the pump diffuser optimization is used to satisfy the performance in two points simultaneously. The three coefficient of the quadratic polynomial which is used to control the three inlet blade angles corresponding to the hub, shroud and the stream surface between (span wise=0.5) are selected as design parameters. Head, efficiency and power of the pump in the two selected point are selected as objective functions. The objective functions in the two selected points are in relations of trade-off. Design of experiments (DOE), steady CFD simulation, response surface method (RSM), Neighborhood Cultivation Genetic Algorisms (NCGA) are used to solve this problem. The DOE theory is applied to reduce the number of tests, three-dimensional simulations are performed to predict the pump performance, the RSM (response surface method) is used to correlate the pump performance to the intermediate variable, NCGA is used to search the pareto solutions along the response surface. The multipoint design optimization method is proved effective in searching the pareto solutions to satisfy the given requirements.

  8. Numerical Investigation on the Influence of Nozzle Lip Thickness on the Flow Field and Performance of an Annular Jet Pump

    Institute of Scientific and Technical Information of China (English)

    LongZhou Xiao; XinPing Long; XueLong Yang

    2014-01-01

    The performance of an annular jet pump ( AJP ) is determined by its area ratio A ( ratio of cross sectional area of throat and annular nozzle) and flow rate ratio q ( ratio of primary and secondary flow rate, Qs/Qj ) , while the nozzle lip thickness is neglected in the present studies. This paper presents a study on the effect of the thickness on the flow field and performance of an AJP with A = 1�75. With the increasing flow rate ratio and nozzle lip thickness, a small vortex forms at the nozzle lip and keeps on growing. However, as the flow rate ratio or nozzle lip thickness is extremely low, the vortex at the lip vanishes thoroughly. Moreover, the recirculation width varies conversely with the nozzle lip thickness when the flow rate ratio q≤0�13. While the deviation of the recirculation width with different nozzle lip thickness is negligible with q≥0�13. Additionally the existence of nozzle lip hinders the momentum exchange between the primary and secondary flow and leads to a mutation of velocity gradient near the nozzle exit, which shift the recirculation downstream. Finally, based on the numerical results of the streamwise and spanwise vortex distributions in the suction chamber, the characteristics of the mixing process and the main factors accounting for the AJP performance are clarified.

  9. Water Pump Development for the EVA PLSS

    Science.gov (United States)

    Schuller, Michael; Kurwitz, Cable; Goldman, Jeff; Morris, Kim; Trevino, Luis

    2009-01-01

    This paper describes the effort by the Texas Engineering Experiment Station (TEES) and Honeywell for NASA to design, fabricate, and test a preflight prototype pump for use in the Extravehicular activity (EVA) portable life support subsystem (PLSS). Major design decisions were driven by the need to reduce the pump s mass, power, and volume compared to the existing PLSS pump. In addition, the pump will accommodate a much wider range of abnormal conditions than the existing pump, including vapor/gas bubbles and increased pressure drop when employed to cool two suits simultaneously. A positive displacement, external gear type pump was selected because it offers the most compact and highest efficiency solution over the required range of flow rates and pressure drops. An additional benefit of selecting a gear pump design is that it is self priming and capable of ingesting noncondensable gas without becoming "air locked." The chosen pump design consists of a 28 V DC, brushless, sealless, permanent magnet motor driven, external gear pump that utilizes a Honeywell development that eliminates the need for magnetic coupling. Although the planned flight unit will use a sensorless motor with custom designed controller, the preflight prototype to be provided for this project incorporates Hall effect sensors, allowing an interface with a readily available commercial motor controller. This design approach reduced the cost of this project and gives NASA more flexibility in future PLSS laboratory testing. The pump design was based on existing Honeywell designs, but incorporated features specifically for the PLSS application, including all of the key features of the flight pump. Testing at TEES will simulate the vacuum environment in which the flight pump will operate. Testing will verify that the pump meets design requirements for range of flow rates, pressure rise, power consumption, working fluid temperature, operating time, and restart capability. Pump testing is currently

  10. Hydrometeorological threshold conditions for debris flow initiation in Norway

    Directory of Open Access Journals (Sweden)

    N. K. Meyer

    2012-10-01

    Full Text Available Debris flows, triggered by extreme precipitation events and rapid snow melt, cause considerable damage to the Norwegian infrastructure every year. To define intensity-duration (ID thresholds for debris flow initiation critical water supply conditions arising from intensive rainfall or snow melt were assessed on the basis of daily hydro-meteorological information for 502 documented debris flow events. Two threshold types were computed: one based on absolute ID relationships and one using ID relationships normalized by the local precipitation day normal (PDN. For each threshold type, minimum, medium and maximum threshold values were defined by fitting power law curves along the 10th, 50th and 90th percentiles of the data population. Depending on the duration of the event, the absolute threshold intensities needed for debris flow initiation vary between 15 and 107 mm day−1. Since the PDN changes locally, the normalized thresholds show spatial variations. Depending on location, duration and threshold level, the normalized threshold intensities vary between 6 and 250 mm day−1. The thresholds obtained were used for a frequency analysis of over-threshold events giving an estimation of the exceedance probability and thus potential for debris flow events in different parts of Norway. The absolute thresholds are most often exceeded along the west coast, while the normalized thresholds are most frequently exceeded on the west-facing slopes of the Norwegian mountain ranges. The minimum thresholds derived in this study are in the range of other thresholds obtained for regions with a climate comparable to Norway. Statistics reveal that the normalized threshold is more reliable than the absolute threshold as the former shows no spatial clustering of debris flows related to water supply events captured by the threshold.

  11. Experimental study of swirl flow patterns in Gas Conditioning Tower at various entry conditions

    DEFF Research Database (Denmark)

    Jinov, Andrei A.; Larsen, Poul Scheel

    1999-01-01

    In a gas conditioning tower hot flue gas with relatively high dust loads is cooled by injecting water spray near the top. For satisfactory operation wet particles should be kept off walls and all water should have evaporated to yield a uniformly cooled flow before it reaches the bottom of the tower...

  12. Relaxed damage threshold intensity conditions and nonlinear increase in the conversion efficiency of an optical parametric oscillator using a bi-directional pump geometry.

    Science.gov (United States)

    Norris, G; McConnell, G

    2010-03-01

    A novel bi-directional pump geometry that nonlinearly increases the nonlinear optical conversion efficiency of a synchronously pumped optical parametric oscillator (OPO) is reported. This bi-directional pumping method synchronizes the circulating signal pulse with two counter-propagating pump pulses within a linear OPO resonator. Through this pump scheme, an increase in nonlinear optical conversion efficiency of 22% was achieved at the signal wavelength, corresponding to a 95% overall increase in average power. Given an almost unchanged measured pulse duration of 260 fs under optimal performance conditions, this related to a signal wavelength peak power output of 18.8 kW, compared with 10 kW using the traditional single-pass geometry. In this study, a total effective peak intensity pump-field of 7.11 GW/cm(2) (corresponding to 3.55 GW/cm(2) from each pump beam) was applied to a 3 mm long periodically poled lithium niobate crystal, which had a damage threshold intensity of 4 GW/cm(2), without impairing crystal integrity. We therefore prove the application of this novel pump geometry provides opportunities for power-scaling of synchronously pumped OPO systems together with enhanced nonlinear conversion efficiency through relaxed damage threshold intensity conditions.

  13. The Flow Of Granular Matter Under Reduced-Gravity Conditions

    CERN Document Server

    Hofmeister, Paul Gerke; Heißelmann, Daniel

    2009-01-01

    To gain a better understanding of the surfaces of planets and small bodies in the solar system, the flow behavior of granular material for various gravity levels is of utmost interest. We performed a set of reduced-gravity measurements to analyze the flow behavior of granular matter with a quasi-2D hourglass under coarse-vacuum conditions and with a tilting avalanche box. We used the Bremen drop tower and a small centrifuge to achieve residual-gravity levels between 0.01 g and 0.3 g. Both experiments were carried out with basalt and glass grains as well as with two kinds of ordinary sand. For the hourglass experiments, the volume flow through the orifice, the repose and friction angles, and the flow behavior of the particles close to the surface were determined. In the avalanche-box experiment, we measured the duration of the avalanche, the maximum slope angle as well as the width of the avalanche as a function of the gravity level.

  14. Laminar flow of an electrically conducting liquid through the channel of a cylindrical linear induction pump

    Energy Technology Data Exchange (ETDEWEB)

    Kapusta, A.B.; Shamota, V.P.

    1979-04-01

    Laminar flow of an electrically conducting viscous incompressible fluid through the gap between two nonconducting, thin, and infinitely long coaxial cylinders is considered. The inner cylinder is filled with a ferromagnetic medium and the surface of the outer cylinder carries a distributed electric load of a uniform current density. The traveling external magnetic field in this problem is replaced with the uniform magnetic field of a long ring magnet moving parallel to the axis of the cylinders at a certain velocity. The continuity equation for the magnetic field reduces the system of second-degree differential MHD equations to a simpler form, with the Hartmann number and the magnetic Reynolds number as well as the N/sub Eu/(Euler).N/sub Re/(Reynolds) complex as the only parameters. The velocity distribution is found on the basis of the appropriate boundary conditions, for N/sub Ha/ = 2 and N/sub Ha/ is not equal to 2, respectively, and subsequently also the distribution of magnetic induction. The solution is exact and simply arrived at, applicable to any value of the Hartmann number or of other parameters. Numerical calculations indicate that large positive pressure gradients result in a high flow intensity at the outer wall, because the density of electromagnetic forces decreases along the radius. 1 reference, 3 figures.

  15. Exercise hemodynamics during extended continuous flow left ventricular assist device support: the response of systemic cardiovascular parameters and pump performance.

    Science.gov (United States)

    Martina, Jerson; de Jonge, Nicolaas; Rutten, Marcel; Kirkels, J Hans; Klöpping, Corinne; Rodermans, Ben; Sukkel, Eveline; Hulstein, Nelienke; Mol, Bas; Lahpor, Jaap

    2013-09-01

    Patients on continuous flow left ventricular assist devices (cf-LVADs) are able to return to an active lifestyle and perform all sorts of physical activities. This study aims to evaluate exercise hemodynamics in patients with a HeartMate II cf-LVAD (HM II). Thirty (30) patients underwent a bicycle exercise test. Along with exercise capacity, systemic cardiovascular responses and pump performance were evaluated at 6 and 12 months after HM II implantation. From rest to maximum exercise, heart rate increased from 87 ± 14 to 140 ± 32 beats/minute (bpm) (P<0.01), while systolic arterial blood pressure increased from 93 ± 12 to 116 ± 21 mm Hg (P<0.01). Total cardiac output (TCO) increased from 4.1 ± 1.1 to 8.5 ± 2.8 L/min (P<0.01) while pump flow increased less, from 5.1 ± 0.7 to 6.4 ± 0.6 L/min (P<0.01). Systemic vascular resistance (SVR) decreased from 1776 ± 750 to 1013 ± 83 dynes.s/cm(5) (P<0.001) and showed the strongest correlation with TCO (r= -0.72; P<0.01). Exercise capacity was affected by older age, while blood pressure increased significantly in men compared with women. Exercise capacity remained consistent at 6 and 12 months after HM II implantation, 51% ± 13% and 52% ± 13% of predicted VO2 max for normal subjects corrected for age and gender. In conclusion, pump flow of the HM II may contribute partially to TCO during exercise, while SVR was the strongest determinant of TCO.

  16. Hydraulic development of high specific-speed pump-turbines by means of an inverse design method, numerical flow-simulation (CFD) and model testing

    Science.gov (United States)

    Kerschberger, P.; Gehrer, A.

    2010-08-01

    In recent years an increased interest in pump-turbines has been recognized in the market. The rapid availability of pumped storage schemes and the benefits to the power system by peak lopping, providing reserve and rapid response for frequency control are becoming of growing advantage. In that context it is requested to develop pump-turbines that reliably stand dynamic operation modes, fast changes of the discharge rate by adjusting the variable diffuser vanes as well as fast changes from pump to turbine operation. Within the present study various flow patterns linked to the operation of a pump-turbine system are discussed. In that context pump and turbine mode are presented separately and different load cases at both operation modes are shown. In order to achieve modern, competitive pump-turbine designs it is further explained which design challenges should be considered during the geometry definition of a pump-turbine impeller. Within the present study a runner-blade profile for a low head pump-turbine has been developed. For the initial hydraulic runner-blade design, an inverse design method has been applied. Within this design procedure, a first blade geometry is generated by imposing the pressure loading-distribution and by means of an inverse 3D potential-flow-solution. The hydraulic behavior of both, pump-mode and turbine-mode is then evaluated by solving the full 3D Navier-Stokes equations in combination with a robust turbulence model. Based on this initial design the blade profile has been further optimized and redesigned considering various hydraulic pump-turbine requirements. Finally, the progress in hydraulic design is demonstrated by model test results which show a significant improvement in hydraulic performance compared to an existing reference design.

  17. Hydraulic development of high specific-speed pump-turbines by means of an inverse design method, numerical flow-simulation (CFD) and model testing

    Energy Technology Data Exchange (ETDEWEB)

    Kerschberger, P; Gehrer, A, E-mail: peter.kerschberger@andritz.co [Andritz Hydro Graz A-8045 Graz, Reichsstrasse 68B (Austria)

    2010-08-15

    In recent years an increased interest in pump-turbines has been recognized in the market. The rapid availability of pumped storage schemes and the benefits to the power system by peak lopping, providing reserve and rapid response for frequency control are becoming of growing advantage. In that context it is requested to develop pump-turbines that reliably stand dynamic operation modes, fast changes of the discharge rate by adjusting the variable diffuser vanes as well as fast changes from pump to turbine operation. Within the present study various flow patterns linked to the operation of a pump-turbine system are discussed. In that context pump and turbine mode are presented separately and different load cases at both operation modes are shown. In order to achieve modern, competitive pump-turbine designs it is further explained which design challenges should be considered during the geometry definition of a pump-turbine impeller. Within the present study a runner-blade profile for a low head pump-turbine has been developed. For the initial hydraulic runner-blade design, an inverse design method has been applied. Within this design procedure, a first blade geometry is generated by imposing the pressure loading-distribution and by means of an inverse 3D potential-flow-solution. The hydraulic behavior of both, pump-mode and turbine-mode is then evaluated by solving the full 3D Navier-Stokes equations in combination with a robust turbulence model. Based on this initial design the blade profile has been further optimized and redesigned considering various hydraulic pump-turbine requirements. Finally, the progress in hydraulic design is demonstrated by model test results which show a significant improvement in hydraulic performance compared to an existing reference design.

  18. Intelligent pump drives. Simulation, condition monitoring, fault diagnosis and energy efficiency; Intelligente Pumpenantriebe. Simulation, Condition Monitoring, Fehlerdiagnose und Energieeffizienz

    Energy Technology Data Exchange (ETDEWEB)

    Kleinmann, Stefan [Allweiler AG, Radolfzell (Germany); Leonardo, Domenico; Koller-Hodac, Agathe [Hochschule fuer Technik Rapperswil (Switzerland)

    2011-07-01

    The authors of the contribution under consideration report on an implementation of a simulation environment and a fault diagnostic system for an oil burner application. Using a modification of the application hardware, an additional increase in efficiency in an advanced control of pump drives is achieved. The properties of the combustion process are not affected adversely. All changes to the system can be investigated in simulations for feasibility and impact. Using the simulation model, a diagnostic system is brought up enabling a remote monitoring for example.

  19. Custom Unit Pump Development for the EVA PLSS

    Science.gov (United States)

    Schuller, Michael; Kurwitz, Cable; Little, Frank; Oinuma, Ryoji; Larsen, Ben; Goldman, Jeff; Reinis, Filip; Trevino, Luis

    2010-01-01

    This paper describes the effort by the Texas Engineering Experiment Station (TEES) and Honeywell for NASA to design and test a pre-flight prototype pump for use in the Extra-vehicular activity (EVA) portable life support subsystem (PLSS). Major design decisions were driven by the need to reduce the pump s mass, power, and volume compared to the existing PLSS pump. In addition, the pump must accommodate a much wider range of abnormal conditions than the existing pump, including vapor/gas bubbles and increased pressure drop when employed to cool two suits simultaneously. A positive displacement, external gear type pump was selected because it offers the most compact and highest efficiency solution over the required range of flow rates and pressure drops. An additional benefit of selecting a gear pump design is that it is self priming and capable of ingesting non-condensable gas without becoming air locked. The chosen pump design consists of a 28 V DC, brushless, seal-less, permanent magnet motor driven, external gear pump that utilizes a Honeywell development that eliminates the need for magnetic coupling. The pump design was based on existing Honeywell designs, but incorporated features specifically for the PLSS application, including all of the key features of the flight pump. Testing at TEES verified that the pump meets the design requirements for range of flow rates, pressure drop, power consumption, working fluid temperature, operating time, gas ingestion, and restart capability under both ambient and vacuum conditions. The pump operated at 40 to 240 lbm/hr flow rate, 35 to 100 oF pump temperature, and 5 to 10 psid pressure rise. Power consumption of the pump controller at the nominal operating point in both ambient and vacuum conditions was 9.5 W, which was less than the 12 W predicted. Gas ingestion capabilities were tested by injecting 100 cc of air into the fluid line; the pump operated normally throughout this test.

  20. Performance tests of air source heat pumps under frosting conditions. Quality of results

    Science.gov (United States)

    Fahlen, P.

    This report focuses on the analysis of uncertainties in research regarding air-source heat pumps. The principles recommended by the Western European Calibration Conference (WECC) are applied and the generated information is condensed in the form of uncertainty budgets. The ensuring discussion, and the Measurement Assurance Program that was applied during the research work are also relevant to general testing of cooling coils, e.g. for air source heat pumps. The general conclusion of the analysis is that the method of determining frost mass by continuous weighing and frost density by inference from pressure drop considerations, which is presented in the report, has the potential to produce results with an accuracy on a par with the best previously used techniques to investigate frosting and defrosting phenomena. Furthermore, the methodology has the distinct advantage of yielding online measuring possibilities and being much less time consuming than traditional techniques.

  1. Continuous Pump Assisted Conditional Synthesis of Nonclassical States in a Dispersive Cavity QED

    Institute of Scientific and Technical Information of China (English)

    GUOJian-Hong

    2003-01-01

    The interaction of N identical atoms with both a quantized cavity field and an external classical pumping field with the fields being degenerate in frequency, is studied in the regime where the atoms and fields are highly detuned. This dispersive interaction can be used to generate coherent states for the cavity field. By preparing the injected atoms in a superposition of the bare atomic states, various types of Schroedinger-cat-like states may be generated.

  2. Pulsatile flow during cardiopulmonary bypass. Evaluation of a new pulsatile pump.

    Science.gov (United States)

    Waaben, J; Andersen, K; Husum, B

    1985-01-01

    Pulsatile cardiopulmonary bypass (CPB) has been suggested to be superior to nonpulsatile CPB. This report concerns a newly developed pulsatile pump for clinical use. It is designed as a positive displacement pump, with blood allowed to collect in a valved cavity from which it is ejected by the reciprocating action of a piston. Using a uniform procedure of anaesthesia and surgery, 14 pigs were subjected to CPB at 37 degrees C for 3 hours. The pulsatile pump was used in seven pigs and a conventional roller pump in the other seven. The wave-form of the pulse during pulsatile CPB was similar to that recorded in the pigs before bypass. The values for rate of pressure change with respect to time (dp/dt) obtained in the aorta were close to the pre-CPB values. No difference was found between the two groups with respect to platelet count or haemolysis. The investigated pulsatile device appeared to be reliable and easy to handle, and the pulsation it produced closely resembled the physiologic pulse-wave form.

  3. Flow regimes and mechanistic modeling of critical heat flux under subcooled flow boiling conditions

    Science.gov (United States)

    Le Corre, Jean-Marie

    Thermal performance of heat flux controlled boiling heat exchangers are usually limited by the Critical Heat Flux (CHF) above which the heat transfer degrades quickly, possibly leading to heater overheating and destruction. In an effort to better understand the phenomena, a literature review of CHF experimental visualizations under subcooled flow boiling conditions was performed and systematically analyzed. Three major types of CHF flow regimes were identified (bubbly, vapor clot and slug flow regime) and a CHF flow regime map was developed, based on a dimensional analysis of the phenomena and available data. It was found that for similar geometric characteristics and pressure, a Weber number (We)/thermodynamic quality (x) map can be used to predict the CHF flow regime. Based on the experimental observations and the review of the available CHF mechanistic models under subcooled flow boiling conditions, hypothetical CHF mechanisms were selected for each CHF flow regime, all based on a concept of wall dry spot overheating, rewetting prevention and subsequent dry spot spreading. It is postulated that a high local wall superheat occurs locally in a dry area of the heated wall, due to a cyclical event inherent to the considered CHF two-phase flow regime, preventing rewetting (Leidenfrost effect). The selected modeling concept has the potential to span the CHF conditions from highly subcooled bubbly flow to early stage of annular flow. A numerical model using a two-dimensional transient thermal analysis of the heater undergoing nucleation was developed to mechanistically predict CHF in the case of a bubbly flow regime. In this type of CHF two-phase flow regime, the high local wall superheat occurs underneath a nucleating bubble at the time of bubble departure. The model simulates the spatial and temporal heater temperature variations during nucleation at the wall, accounting for the stochastic nature of the boiling phenomena. The model has also the potential to evaluate

  4. AIR FLOW AND ENVIRONMENTAL WIND VISUALIZATION USING A CW DIODE PUMPED FREQUENCY DOUBLED Nd:YAG Laser

    Directory of Open Access Journals (Sweden)

    Mircea UDREA

    2009-09-01

    Full Text Available Preliminary results obtained in developing a visualisation technique for non-invasive analysis of air flow inside INCAS subsonic wind tunnel and its appendages are presented. The visualisation technique is based on using a green light sheet generated by a continuous wave (cw longitudinally diode pumped and frequency doubled Nd:YAG laser. The output laser beam is expanded on one direction and collimated on rectangular direction. The system is tailored to the requirements of qualitative analysis and vortex tracking requirements inside the INCAS 2.5m x 2.0m subsonic wind tunnel test section, for measurements performed on aircraft models. Also the developed laser techniques is used for non-invasive air flow field analysis into environmental facilities settling room (air flow calming area. Quantitative analysis is enabled using special image processing tools upon movies and pictures obtained during the experiments. The basic experimental layout in the wind tunnel takes advantage of information obtained from the investigation of various aircraft models using the developed visualisation technique. These results are further developed using a Particle Imaging Velocimetry (PIV experimental technique.The focus is on visualisation techniques to be used for wind flow characterization at different altitudes in indus-trial and civil buildings areas using a light sheet generated by a Nd:YAG cw pumped and doubled laser at 532 nm wave-length. The results are important for prevention of biological/chemical disasters such as spreading of extremely toxic pol-lutants due to wind. Numerical simulations of wind flow and experimental visualisation results are compared. A good agreement between these results is observed.

  5. Characteristics of Flow in Large Vertical Axial Flow Pumping System%大型立式轴流泵装置流道内部流动特性分析

    Institute of Scientific and Technical Information of China (English)

    杨帆; 刘超; 汤方平; 周济人

    2011-01-01

    基于三维不可压缩流体的雷诺平均N-S方程和RNGk-ε湍流模型,采用CFX软件计算了额定转速下180~340 L/s流量范围内6个工况点的立式轴流泵装置内部流动,分析了进水流道和出水流道的流动特性,重点研究进口流动细部结构,同时预测了泵装置的水力性能.计算结果表明:叶轮旋转对进水流道出口轴向流速分布和切向流速分布的影响较小.导叶出口环量对出水流道的流场影响较大,导致隔墩两侧流量分配不均,大流量时隔墩两侧水流流态比较平顺,而小流量时隔墩右侧流道内出现螺旋状水流,两侧水流严重不均衡.通过计算预测了泵装嚣水力性能,并与泵装置模型性能试验结果进行了对比,表明最优工况时数值模拟与试验结果吻合较理想,可以满足工程实际的需要.%The internal flow field in a vertical axial flow pumping system was simulated by CFX software using the Reynolds averaged N - S equations and RNG k - s turbulence model. Focusing on details of the inlet flow field, the flow characteristics in the inlet and outlet passages of pumping system were analyzed based on the calculation of different operating conditions with the flow rates range 180 ~ 340 L/s at the rated rotating speed. The results show that rotating of impeller has effects on the distribution of axial and tangential velocity components at the pump inlet, but the numerical values are relatively small. Outlet circulation of guide vane has great influence on flow pattern in the outlet passage. The flow distribution for both sides of the dividing pier is not symmetric, especially for small flow rate condition, the helical flow occurs at the right side of dividing pier. A good agreement is achieved in the performances of the pumping system between the predicted data and experimental data at the best efficiency point, which can meet the requirement of practical application.

  6. Physical Model Study: Rill Erosion Morphology and Flow Conditions

    Science.gov (United States)

    Strohmeier, S.; Klik, A.; Nouwakpo, S. K.

    2012-04-01

    Using common catchment size erosion model software either lack of knowledge or lack in process ability of watershed characteristics leads to increasing simplifications in model assumptions. Referring to open channel hydraulics, erosion model equations are prevalently based on stepwise uniform flow condition requirements. Approaching balance of gravitational and frictional resistance forces, channel roughness is fundamental model input. The fusion of simplified model assumptions and the use of lumped roughness determination cause ambivalence in model calibration. By means of a physical model experiment at the National Soil Erosion Laboratory (NSERL), West Lafayette, USA, channel roughness was itemized into skin friction and channel shape friction due to rill morphology. Particularly the Manning-Strickler equation was analyzed concerning the applicability of constant and holistic factors describing boundary friction impacts. The insufficiency in using the Manning-Strickler equation for non-uniform flow conditions is widely advised, whereas lack in predictability in rill erosion development inhibits proper model adoptions. The aim of the present study is to determine the impact of channel morphology on roughness assessment in rill erosion scale. Therefore a 1.9 meter long, 0.6 meter wide and 0.3 meter deep flume with an inclination of 10 % was filled with a loamy soil representing a section of a hill slope. The soil was prepared and saturated by simulated rainfall before each model run. A single erosion channel was enforced to develop by means of steady state runoff. Two different erosion channel types were initiated and observed: I.) a Straight Constrained Rill (SCR) shape by concentration of the runoff into a prepared straight initial rill and II.) a Free Developing Rill (FDR) by back-cut erosion through the plain soil body. Discharge of the outflow was measured in 5 minute interval and outflow sediment concentration was measured every minute. A top view stereo

  7. Research of the Internal Micro-Flow Pump in Slanting Shaft Plunger Pump%斜轴式柱塞泵内部微流量泵的研究

    Institute of Scientific and Technical Information of China (English)

    赵铁军

    2014-01-01

    通过对斜轴式柱塞泵的结构的研究,阐述了斜轴式柱塞泵内部微流量泵存在的必要和理论依据,分析了微流量泵排出的油液对斜轴式柱塞泵主轴轴承进行冷却的机理,并推道出热平衡计算方程,导出了其排量计算公式。%By research the structure of the Slanting Shaft Plunger Pump,the paper puts forward the theory of the micro-flow pump in the Slanting Shaft Plunger Pump and points out the expression to calculate the displacement of the micro-flow pump;Analyzing the process which the fluid piped out by the micro-flow pump cools the main shaft bearings,derives the formula of heat exchange.

  8. Boundary conditions for soft glassy flows: slippage and surface fluidization.

    Science.gov (United States)

    Mansard, Vincent; Bocquet, Lydéric; Colin, Annie

    2014-09-28

    We explore the question of surface boundary conditions for the flow of a dense emulsion. We make use of microlithographic tools to create surfaces with well controlled roughness patterns and measure using dynamic confocal microscopy both the slip velocity and the shear rate close to the wall, which we relate to the notion of surface fluidization. Both slippage and wall fluidization depend non-monotonously on the roughness. We interpret this behavior within a simple model in terms of the building of a stratified layer and the activation of plastic events by the surface roughness.

  9. Stretched flow of Carreau nanofluid with convective boundary condition

    Indian Academy of Sciences (India)

    T Hayat; M Waqas; S A Shehzad; A Alsaedi

    2016-01-01

    The steady laminar boundary layer flow of Carreau nanofluid over a stretching sheet is investigated. Effects of Brownian motion and thermophoresis are present. Heat transfer is characterized using convective boundary condition at the sheet. The governing partial differential equations are reduced into a set of nonlinear ordinary differential equations through suitable transformations. Results of velocity, temperature and concentration fields are computed via homotopic procedure. Numerical values of skin-friction coefficient, local Nusselt and Sherwood numbers are computed and discussed. A comparative study with existing solutions in a limiting sense is made.

  10. Quantifying Systemic Efficiency using Exergy and Energy Analysis for Ground Source Heat Pumps: Domestic Space Conditioning and Water Heating Applications.

    Energy Technology Data Exchange (ETDEWEB)

    Ally, Moonis Raza [ORNL; Baxter, Van D [ORNL; Gehl, Anthony C [ORNL; Munk, Jeffrey D [ORNL

    2017-01-01

    Although air temperatures over land surfaces show wide seasonal and daily variations, the ground, approximately 10 meters below the earth s surface, remains relatively stable in temperature thereby serving as an energy source or sink. Ground source heat pumps can heat, cool, and supply homes with hot water efficiently by utilizing the earth s renewable and essentially inexhaustible energy resources, saving fossil fuels, reducing greenhouse gas emissions, and lowering the environmental footprint. In this paper, evidence is shown that ground source heat pumps can provide up to 79%-87% of domestic hot water energy needs, and up to 77% of space heating needs with the ground s thermal energy resources. The case refers to a 12-month study conducted at a 253 m2 research house located in Oak Ridge, Tennessee, 36.01 N 84.26 W in a mixed-humid climate with HDD of 2218 C-days and CDD of 723 C-days under simulated occupancy conditions. A single 94.5m vertical bore interfaced the heat pump with the ground. The research shows that this technology is capable of achieving US DOE targets of 25 % and 35% energy savings in HVAC, and in water heating, respectively by 2030. It is also a viable technology to meet greenhouse gas target emissions under the IECC 2012 Standard, as well as the European Union (EU) 2020 targets of using renewable energy resources. The paper quantifies systemic efficiencies using Exergy analysis of the major components, clearly pointing areas for further improvement.

  11. Modelling of transit-time ultrasonic flow meters under multi-phase flow conditions

    DEFF Research Database (Denmark)

    Simurda, Matej; Duggen, Lars; Lassen, Benny

    2016-01-01

    A pseudospectral model for transit time ultrasonic flowmeters under multiphase flow conditions is presented. The method solves first order stress-velocity equations of elastodynamics, with acoustic media being modelled by setting shear modulus to zero. Additional terms to account for the effect...... of the background flow are included. Spatial derivatives are calculated by a Fourier collocation scheme allowing the use of the Fast Fourier transform. The method is compared against analytical solutions and experimental measurements. Additionally, a study of clamp-on and in-line ultrasonic flowmeters operating...

  12. Revisiting Johnson and Jackson boundary conditions for granular flows

    Energy Technology Data Exchange (ETDEWEB)

    Li, Tingwen; Benyahia, Sofiane

    2012-07-01

    In this article, we revisit Johnson and Jackson boundary conditions for granular flows. The oblique collision between a particle and a flat wall is analyzed by adopting the classic rigid-body theory and a more realistic semianalytical model. Based on the kinetic granular theory, the input parameter for the partial-slip boundary conditions, specularity coefficient, which is not measurable in experiments, is then interpreted as a function of the particle-wall restitution coefficient, the frictional coefficient, and the normalized slip velocity at the wall. An analytical expression for the specularity coefficient is suggested for a flat, frictional surface with a low frictional coefficient. The procedure for determining the specularity coefficient for a more general problem is outlined, and a working approximation is provided.

  13. Bridge Pressure Flow Scour at Clear Water Threshold Condition

    Institute of Scientific and Technical Information of China (English)

    GUO Junke; KERENYI Kornel; PAGAN-ORTIZ Jorge E; FLORA Kevin

    2009-01-01

    Bridge pressure flow scour at clear water threshold condition is studied theoretically and experimentally. The flume experiments reveal that the measured scour profiles under a bridge are more or less 2-dimensional; all the measured scour profiles can be described by two similarity equations, where the horizontal distance is scaled by the deck width while the local scour by the maximum scour depth; the maximum scour position is located just under the bridge about 15% deck width from the downstream deck edge; the scour begins at about one deck width upstream the bridge while the deposition occurs at about 2.5 deck widths downstream the bridge; and the maximum scour depth decreases with increas-ing sediment size, but increases with deck inundation. The theoretical analysis shows that: bridge scour can be divided into three cases, i.e. downstream unsubmerged, partially submerged, and totally submerged. For downstream unsubmerged flows, the maximum bridge scour depth is an open-channel problem where the conventional methods in terms of critical velocity or bed shear stress can be applied; for partially and totally submerged flows, the equilibrium maximum scour depth can be described by a scour and an inundation similarity number, which has been confirmed by experiments with two decks and two sediment sizes. For application, a design and field evaluation procedure with examples is presented, including the maximum scour depth and scour profile.

  14. PLATELET ADHESION TO POLYURETHANE UREA UNDER PULSATILE FLOW CONDITIONS

    Science.gov (United States)

    Navitsky, Michael A.; Taylor, Joshua O.; Smith, Alexander B.; Slattery, Margaret J.; Deutsch, Steven; Siedlecki, Christopher A.; Manning, Keefe B.

    2014-01-01

    Platelet adhesion to a polyurethane urea surface is a precursor to thrombus formation within blood-contacting cardiovascular devices, and platelets have been found to adhere strongly to polyurethane surfaces below a shear rate of approximately 500 s−1. The aim of the current work is to determine platelet adhesion properties to the polyurethane urea surface as a function of time varying shear exposure. A rotating disk system is used to study the influence of steady and pulsatile flow conditions (e.g. cardiac inflow and sawtooth waveforms) for platelet adhesion to the biomaterial surface. All experiments retain the same root mean square angular rotation velocity (29.63 rad/s) and waveform period. The disk is rotated in platelet rich bovine plasma for two hours with adhesion quantified by confocal microscopy measurements of immunofluorescently labeled bovine platelets. Platelet adhesion under pulsating flow is found to exponentially decay with increasing shear rate. Adhesion levels are found to depend upon peak platelet flux and shear rate regardless of rotational waveform. In combination with flow measurements, these results may be useful for predicting regions susceptible to thrombus formation within ventricular assist devices. PMID:24721222

  15. Platelet adhesion to polyurethane urea under pulsatile flow conditions.

    Science.gov (United States)

    Navitsky, Michael A; Taylor, Joshua O; Smith, Alexander B; Slattery, Margaret J; Deutsch, Steven; Siedlecki, Christopher A; Manning, Keefe B

    2014-12-01

    Platelet adhesion to a polyurethane urea surface is a precursor to thrombus formation within blood-contacting cardiovascular devices, and platelets have been found to adhere strongly to polyurethane surfaces below a shear rate of approximately 500 s(-1). The aim of the current work is to determine the properties of platelet adhesion to the polyurethane urea surface as a function of time-varying shear exposure. A rotating disk system was used to study the influence of steady and pulsatile flow conditions (e.g., cardiac inflow and sawtooth waveforms) for platelet adhesion to the biomaterial surface. All experiments were conducted with the same root mean square angular rotation velocity (29.63 rad/s) and waveform period. The disk was rotated in platelet-rich bovine plasma for 2 h, with adhesion quantified by confocal microscopy measurements of immunofluorescently labeled bovine platelets. Platelet adhesion under pulsating flow was found to decay exponentially with increasing shear rate. Adhesion levels were found to depend upon peak platelet flux and shear rate, regardless of rotational waveform. In combination with flow measurements, these results may be useful for predicting regions susceptible to thrombus formation within ventricular assist devices.

  16. In-line pressure within a HOTLINE® Fluid Warmer, under various flow conditions.

    Science.gov (United States)

    Higashi, Midoriko; Yamaura, Ken; Matsubara, Yukie; Fukudome, Takuya; Hoka, Sumio

    2015-04-01

    Roller pump infusion devices are widely used for rapid infusion, and may be combined with separate warming devices. There may be instances however, where the pressures generated by the roller pump may not be compatible with the warming device. We assessed a commonly used roller pump in combination with a HOTLINE® Fluid Warmer, and found that it could generate pressures exceeding the HOTLINE® manufacturers specifications. This was of concern because the HOTLINE® manufacturer guideline states that not for use with pressure devices generating over 300 mmHg. Pressure greater than 300 mmHg may compromise the integrity of the HOTLINE® Fluid Warming Set. The aim of this study was to compare in-line pressure within a HOTLINE® Fluid Warmer at different infusion rates of a roller pump using various sizes of intravenous cannulae. The rapid infusion system comprised a 500 mL-normal saline bag, roller pump type infusion device, HOTLINE® Fluid Warmer (blood and fluid warmer system), and six different sizes of intravenous cannulae. In-line pressure was measured proximal to the HOTLINE® (pre-warmer) and proximal to the cannula (post-warmer), at flow rate of 50-160 mL/min. The in-line pressures increased significantly with increasing flow rate. The pre-warmer pressures exceeded 300 mmHg when the flow rate was ≥120 mL/min with 20-gauge, 48 mm length cannula, 130 with 20-gauge, 25 mm cannula, and 160 mL/min with 18-gauge, 48 mm cannula. However, they were HOTLINE® could exceed 300 mmHg, depending on the flow rate and size and length of cannula. It is important to pay attention to the size and length of cannulae and flow rate to keep the maximum in-line pressure<300 mmHg when a roller pump type infusion device is used.

  17. Heat Transfer with Flow and Phase Change in an Evaporator of Miniature Flat Plate Capillary Pumped Loop

    Institute of Scientific and Technical Information of China (English)

    Zhongmin WAN; Wei LIU; Zhaoqing ZHENG; A. Nakayama

    2007-01-01

    An overall two-dimensional numerical model of the miniature flat plate capillary pumped loop (CPL) evaporator is developed to describe the liquid and vapor flow, heat transfer and phase change in the porous wick structure,liquid flow and heat transfer in the compensation cavity and heat transfer in the vapor grooves and metallic wall.The entire evaporator is solved with SIMPLE algorithm as a conjugate problem. The effect of heat conduction of metallic side wall on the performance of miniature flat plate CPL evaporator is analyzed, and side wall effect heat transfer limit is introduced to estimate the performance of evaporator. The shape and location of vapor-liquid interface inside the wick are calculated and the influences of applied heat flux, liquid subcooling, wick material and metallic wall material on the evaporator performance are investigated in detail. The numerical results obtained are useful for the miniature flat plate evaporator performance optimization and design of CPL.

  18. Energy Savings Potential for Pumping Water in District Heating Stations

    Directory of Open Access Journals (Sweden)

    Ioan Sarbu

    2015-05-01

    Full Text Available In district heating stations, the heat carrier is circulated between the energy source and consumers by a pumping system. Fluid handling systems, such as pumping systems, are responsible for a significant portion of the total electrical energy use. Significant opportunities exist to reduce pumping energy through smart design, retrofitting, and operating practices. Most existing systems requiring flow control make use of bypass lines, throttling valves or pump speed adjustments. The most efficient of these options is pump speed control. One of the issues in using variable-speed pumping systems, however, is the total efficiency of the electric motor/pump arrangement under a given operating condition. This paper provides a comprehensive discussion about pump control in heating stations and analyzes the energy efficiency of flow control methods. Specific attention is also given to the selection of motor types, sizing and pump duty cycle. A comparative energy analysis is performed on the hot water discharge adjustment using throttling control valves and variable-speed drives in a district heating station constructed in Romania. To correlate the pumped flow rate with the heat demand and to ensure the necessary pressure using minimum energy, an automatic system has been designed. The performances of these control methods are evaluated in two practical applications. The results show that approximately 20%–50% of total pumping energy could be saved by using the optimal control method with variable-speed pumps. Additionally, some modernization solutions to reduce the environmental impact of heating stations are described.

  19. Performance enhancement of a pump impeller using optimal design method

    Science.gov (United States)

    Jeon, Seok-Yun; Kim, Chul-Kyu; Lee, Sang-Moon; Yoon, Joon-Yong; Jang, Choon-Man

    2017-04-01

    This paper presents the performance evaluation of a regenerative pump to increase its efficiency using optimal design method. Two design parameters which define the shape of the pump impeller, are introduced and analyzed. Pump performance is evaluated by numerical simulation and design of experiments(DOE). To analyze three-dimensional flow field in the pump, general analysis code, CFX, is used in the present work. Shear stress turbulence model is employed to estimate the eddy viscosity. Experimental apparatus with an open-loop facility is set up for measuring the pump performance. Pump performance, efficiency and pressure, obtained from numerical simulation are validated by comparison with the results of experiments. Throughout the shape optimization of the pump impeller at the operating flow condition, the pump efficiency is successfully increased by 3 percent compared to the reference pump. It is noted that the pressure increase of the optimum pump is mainly caused by higher momentum force generated inside blade passage due to the optimal blade shape. Comparisons of pump internal flow on the reference and optimum pump are also investigated and discussed in detail.

  20. A Methodology for the Optimization of Flow Rate Injection to Looped Water Distribution Networks through Multiple Pumping Stations

    Directory of Open Access Journals (Sweden)

    Christian León-Celi

    2016-12-01

    Full Text Available The optimal function of a water distribution network is reached when the consumer demands are satisfied using the lowest quantity of energy, maintaining the minimal pressure required at the same time. One way to achieve this is through optimization of flow rate injection based on the use of the setpoint curve concept. In order to obtain that, a methodology is proposed. It allows for the assessment of the flow rate and pressure head that each pumping station has to provide for the proper functioning of the network while the minimum power consumption is kept. The methodology can be addressed in two ways: the discrete method and the continuous method. In the first method, a finite set of combinations is evaluated between pumping stations. In the continuous method, the search for the optimal solution is performed using optimization algorithms. In this paper, Hooke–Jeeves and Nelder–Mead algorithms are used. Both the hydraulics and the objective function used by the optimization are solved through EPANET and its Toolkit. Two case studies are evaluated, and the results of the application of the different methods are discussed.

  1. Elliptic Flow from Nonequilibrium Color Glass Condensate Initial Conditions

    CERN Document Server

    Ruggieri, M; Plumari, S; Greco, V

    2013-01-01

    A current goal of relativistic heavy ion collisions experiments is the search for a Color Glass Condensate as the limiting state of QCD matter at very high density. In viscous hydrodynamics simulations, a standard Glauber initial condition leads to estimate $4\\pi \\eta/s \\sim 1$, while a Color Glass Condensate modeling leads to at least a factor of 2 larger $\\eta/s$. Within a kinetic theory approach based on a relativistic Boltzmann-like transport simulation, we point out that the out-of-equilibrium initial distribution proper of a Color Glass Condensate reduces the efficiency in building-up the elliptic flow. Our main result at RHIC energy is that the available data on $v_2$ are in agreement with a $4\\pi \\eta/s \\sim 1$ also for Color Glass Condensate initial conditions, opening the possibility to describe self-consistently also higher order flow, otherwise significantly underestimated, and to pursue further the search for signatures of the Color Glass Condensate.

  2. Impeller radial force evolution in a large double-suction centrifugal pump during startup at the shut-off condition

    Energy Technology Data Exchange (ETDEWEB)

    Zou, Zhichao [College of Water Resources and Civil Engineering, China Agricultural University, Beijing 100083 (China); Wang, Fujun, E-mail: wangfj@cau.edu.cn [College of Water Resources and Civil Engineering, China Agricultural University, Beijing 100083 (China); Beijing Engineering Research Center of Safety and Energy Saving Technology for Water Supply Network System, China Agricultural University, Beijing 100083 (China); Yao, Zhifeng [College of Water Resources and Civil Engineering, China Agricultural University, Beijing 100083 (China); Beijing Engineering Research Center of Safety and Energy Saving Technology for Water Supply Network System, China Agricultural University, Beijing 100083 (China); Tao, Ran [College of Water Resources and Civil Engineering, China Agricultural University, Beijing 100083 (China); Xiao, Ruofu [College of Water Resources and Civil Engineering, China Agricultural University, Beijing 100083 (China); Beijing Engineering Research Center of Safety and Energy Saving Technology for Water Supply Network System, China Agricultural University, Beijing 100083 (China); Li, Huaicheng [Shanghai Liancheng (Group) Co., Ltd., Shanghai 201812 (China)

    2016-12-15

    Highlights: • Conclude the characteristics of transient radial force in the startup process for a large double-suction centrifugal pump. • The overall direction of the radial force during startup process is also confirmed. • A formula used to calculate the transient radial force during startup process is proposed. • A relationship between radial force variation and axial vortex development in blade channel during the startup process is established. The mechanism of the radial force evolution is revealed. - Abstract: Double-suction centrifugal pumps play an important role in the main feedwater systems of nuclear power plant. The impeller radial force in a centrifugal pump varies dramatically during startup at the shut-off condition. In this study, the startup process of a large double-suction centrifugal pump is investigated using CFD. During testing, the impeller speed is accelerated from zero to its rated speed in 1.0 s (marked as t{sub 0}) and is then maintained at the rated speed. The results show that the radial force increase lags behind the impeller speed increase. At 0–0.4t{sub 0}, the radial force is small (approaching zero). At 0.4–1.4t{sub 0}, the radial force increases rapidly. After 1.4t{sub 0}, the average radial force stabilizes and reaches its maximum value of 55,619 N. The observed maximum radial force value during startup is approximately nine times as high as the radial force under rated condition. During startup, the overall radial force direction is proximate to the radial line located 25° from the volute tongue along circumferential direction. A transient radial force formula is proposed to evaluate the changes in radial force during startup. The streamline distribution in impeller passages and the impeller outlet pressure profile varying over time are produced. The relationship between radial force evolution and the varying axial-to-spiral vortex structure is analyzed. The radial force change mechanism is revealed. This research

  3. Temperature distribution of air source heat pump barn with different air flow

    Science.gov (United States)

    He, X.; Li, J. C.; Zhao, G. Q.

    2016-08-01

    There are two type of airflow form in tobacco barn, one is air rising, the other is air falling. They are different in the structure layout and working principle, which affect the tobacco barn in the distribution of temperature field and velocity distribution. In order to compare the temperature and air distribution of the two, thereby obtain a tobacco barn whose temperature field and velocity distribution are more uniform. Taking the air source heat pump tobacco barn as the investigated subject and establishing relevant mathematical model, the thermodynamics of the two type of curing barn was analysed and compared based on Fluent. Provide a reasonable evidence for chamber arrangement and selection of outlet for air source heat pump tobacco barn.

  4. The Use of Centrifugal Flow Pumps in a Model of Experimental Right Heart Failure

    Science.gov (United States)

    1988-12-01

    clinical situations such as right ventricular in- farction, pulmonary hypertension , and pulmonary embolism. O"" 147 E0ION OF I NOV 6S IS OBSOLETE SD C...study was to an- pulmonary hypertension , and pulmonary em- swer three questions: Can ischemic right bolism. - ventricular failure be induced...proximal 4 pulmonar . a rtc r., S3 AL B2 gation baseline values were reached for the 2 84 values outlined earlier. The pump was then turned off and the

  5. Energy conservation by application of a volume-flow-dependent linear speed control for pumps and blowers. Energiebesparing met volumestroomafhankelijke toerenregeling voor pompen en ventilatoren

    Energy Technology Data Exchange (ETDEWEB)

    Slagt, G. (Nederlands Omroepproduktie Bedrijf NV, Hilversum (Netherlands))

    1990-06-01

    The Energie-Einspar-Technik uses a sensor to measure flow rates. A coupled microprocessor is used to control the thyristor power control unit or the frequency transformer of an electromotor. Two pumps, driven by 22 kW-electromotors and used for coldwater transport in buildings, are compared in order to test this system. The thyristor power control unit of one of the electromotors was replaced by a frequency transformer controlled by the microprocessor. Energy conservation for the latter electromotor has been 35% during the test period (15 days for each pump; the pumps can replace one another). Measured electric power consumption data are presented. 1 ill., 1 tab.

  6. BASIC FLOW PATTERNS AND OPTIMUM HYDRAULIC DESIGN OF A SUCTION BOX OF PUMPING STATION

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    A numerical method based on 3-D turbulence flow was applied to simulate the flow pattern in suction boxes of six different types.In light of the computational results, the basic flow patterns in the boxes were revealed and a theoretical method to optimize hydraulically design of the suction box is developed.The box geometrical parameters, which influence the flow pattern in the box, could be optimized.The optimum criteria for the hydraulic design of the suction boxes of six types established, respectively.Furthermore, a summarization is given here based on the classification of the basic flow patterns in order to systematically understand the hydraulic design of suction boxes.

  7. Numerical Calculation of Secondary Flow in Pump Volute and Circular Casings using 3D Viscous Flow Techniques

    Directory of Open Access Journals (Sweden)

    K. Majidi

    2000-01-01

    Full Text Available The flow field in volute and circular casings interacting with a centrifugal impeller is obtained by numerical analysis. In the present study, effects of the volute and circular casings on the flow pattern have been investigated by successively combining a volute casing and a circular casing with a single centrifugal impeller. The numerical calculations are carried out with a multiple frame of reference to predict the flow field inside the entire impeller and casings. The impeller flow field is solved in a rotating frame and the flow field in the casings in a stationary frame. The static pressure and velocity in the casing and impeller, and the static pressures and secondary velocity vectors at several cross-sectional planes of the casings are calculated. The calculations show that the curvature of the casings creates pressure gradients that cause vortices at cross-sectional planes of the casings.

  8. An analytical model for flow induced by a constant-head pumping in a leaky unconfined aquifer system with considering unsaturated flow

    Science.gov (United States)

    Lin, Ye-Chen; Li, Ming-Hsu; Yeh, Hund-Der

    2017-09-01

    A new mathematical model is developed to describe the flow in response to a constant-head pumping (or constant-head test, CHT) in a leaky unconfined aquifer system of infinite lateral extent with considering unsaturated flow. The model consists of an unsaturated zone on the top, an unconfined aquifer in the middle, and a second aquifer (aquitard) at the bottom. The unsaturated flow is described by Richard's equation, and the flows in unconfined aquifer and second layer are governed by the groundwater flow equation. The well partially penetrates the unconfined aquifer with a constant head in the well due to CHT. The governing equations of the model are linearized by the perturbation method and Gardner's exponential model is adopted to describe the soil retention curves. The solution of the model for drawdown distribution is obtained by applying the methods of Laplace transform and Weber transform. Then the solution for the wellbore flowrate is derived from the drawdown solution with Darcy's law. The issue of the equivalence of normalized drawdown predicted by the present solution for constant-head pumping and Tartakovsky and Neuman's (2007) solution for constant-rate pumping is discussed. On the basis of the wellbore flowrate solution, the results of the sensitivity analysis indicate that the wellbore flowrate is very sensitive to the changes in the radial hydraulic conductivity and the thickness of the saturated zone. Moreover, the results predicted from the present wellbore flowrate solution indicate that this new solution can reduce to Chang's et al. (2010a) solution for homogenous aquifers when the dimensionless unsaturated exponent approaches 100. The unsaturated zone can be considered as infinite extent in the vertical direction if the thickness ratio of the unsaturated zone to the unconfined aquifer is equal to or greater than one. As for the leakage effect, it can be ignored when the vertical hydraulic conductivity ratio (i.e., the vertical hydraulic

  9. 低扬程大流量泵装置马鞍区的流动特性%Flow characteristics of low-lift and large flow rate pump installation in saddle zone

    Institute of Scientific and Technical Information of China (English)

    郑源; 茅媛婷; 周大庆; 张单

    2011-01-01

    运用数值模拟与模型试验相结合的方法,采用计算流体动力学软件Fluent,在双参考坐标系下,利用有限体积法对雷诺时均Navier-Stokes方程进行数值离散,选用标准k-ε湍流模型,SIMPLEC方法求解,对轴流泵模型装置20%~130%额定流量工况点的外特性进行了数值模拟,并将计算结果与模型试验结果进行对比.通过对设计工况和小流量马鞍区工况下CFD流态图样的对比分析,对马鞍区的流动特性进行了研究.结果表明:在50%~65%设计流量区域存在轴流泵的运行不稳定马鞍区;小流量工况下泵室内转轮进出口均存在大范围的回流和旋涡,激烈的能量交换是轴流泵出现不稳定区、装置无法稳定运行的主要原因;数值模拟与模型试验结果吻合较好,整体误差不超过5%,由此证明了数值模拟的有效性和准确性.%Numerical and experimental methods were applied to investigate the axial pump flow characteristics in the saddle zone. The standard k-e turbulence model and SIMPLEC algorithm were chosen in computation fluid dynamics software Fluent, the Reynolds-averaged Navier-Stokes equation was dispersed by the finite volume method, and external characteristics of axial pump model were numerical simulated in a test facility from 20% to 130% of designed flow rate. The results between numerical calculation and model experiment were compared. Flow characteristics in saddle zone were studied by comparing flow patterns between designed condition and small flow rate condition. The results show that unsteady operation saddle zone exists between 50% of designed flow rate and 65% of designed flow rate. Large range recirculation and vortex exist at the inlet and outlet of the impeller under small flow rate condition. Intensive power-exchange is the main cause of the pump unstable operation. The results of three dimensions CFD simulation and test results agree well near the best efficiency point, and

  10. Estimation of Filling and Afterload Conditions by Pump Intrinsic Parameters in a Pulsatile Total Artificial Heart.

    Science.gov (United States)

    Cuenca-Navalon, Elena; Laumen, Marco; Finocchiaro, Thomas; Steinseifer, Ulrich

    2016-07-01

    A physiological control algorithm is being developed to ensure an optimal physiological interaction between the ReinHeart total artificial heart (TAH) and the circulatory system. A key factor for that is the long-term, accurate determination of the hemodynamic state of the cardiovascular system. This study presents a method to determine estimation models for predicting hemodynamic parameters (pump chamber filling and afterload) from both left and right cardiovascular circulations. The estimation models are based on linear regression models that correlate filling and afterload values with pump intrinsic parameters derived from measured values of motor current and piston position. Predictions for filling lie in average within 5% from actual values, predictions for systemic afterload (AoPmean , AoPsys ) and mean pulmonary afterload (PAPmean ) lie in average within 9% from actual values. Predictions for systolic pulmonary afterload (PAPsys ) present an average deviation of 14%. The estimation models show satisfactory prediction and confidence intervals and are thus suitable to estimate hemodynamic parameters. This method and derived estimation models are a valuable alternative to implanted sensors and are an essential step for the development of a physiological control algorithm for a fully implantable TAH.

  11. Oxygenation to Bovine Blood in Artificial Heart and Lung Using Vibrating Flow Pump: Experiment and Numerical Analysis Based on Non-Newtonian Model

    Science.gov (United States)

    Shintaku, Hirofumi; Yonemura, Tsubasa; Tsuru, Kazuaki; Isoyama, Takashi; Yambe, Tomoyuki; Kawano, Satoyuki

    In this study, we construct an experimental apparatus for a prototype artificial heart and lung (AHL) by installing hollow fibers into the cylindrical tube of the vibrating flow pump (VFP). The oxygenation characteristics are investigated both by experiments using bovine blood and by numerical analyses based on the computational fluid dynamics. The analyses are carried out at the Reynolds numbers Re ranged from O(1) to O(103), which are determined based on the experimental conditions. The blood flow and the diffusion of oxygen gas are analyzed based on the Newtonian/non-Newtonian, unsteady, incompressible and axisymmetric Navier-Stokes equations, and the advection-diffusion equation. The results show that the oxygenation rate increases in proportion to Re1/3, where the phenomenon corresponds to the decreasing thickness of the concentration boundary layer with Re. Although the effects of the vibrating flow and the rheology of the blood are clearly appeared on the velocity field, their effects on the gas exchange are relatively small at the ranges of prescribed Reynolds numbers. Furthermore, the numerical results in terms of the oxygenation rate are compared with the experimental ones. The basic design data of VFP were accumulated for the development of AHL in the clinical applications.