Sample records for viscous impeller pump

  1. A parametric study for improving the centrifugal pump impeller for use in viscous fluid pumping

    NASA Astrophysics Data System (ADS)

    Shojaeefard, M. H.; Tahani, M.; Khalkhali, A.; Ehghaghi, M. B.; Fallah, H.; Beglari, M.

    2013-02-01

    Essentially, performance of centrifugal pumps is affected when pumping viscous fluids. In this paper a new idea is proposed to overcome the undesirable effects of viscosity on the pump performance parameters. This idea based on this matter that one specific impeller can be designed, made and installed on the pump for pumping of one fluid with specific viscosity. Therefore a specific pump can be used for pumping of different fluids with different viscosity, by replacement of pump impeller. Replacement of the impeller is more cost effective in comparison to the replacement of the whole of the pump. Passage width and outlet angle of impeller are considered as design variables and the effects of such variables investigated using experimentally validated numerical model. The H-Q, P-Q and ?-Q graphs are extracted experimentally for the improved impeller, which show good improvement in comparison with original impeller.

  2. Cavopulmonary assist for the univentricular Fontan circulation: von Kármán Viscous Impeller Pump (VIP™)

    PubMed Central

    Rodefeld, Mark D; Coats, Brandon; Fisher, Travis; Giridharan, Guruprasad A; Chen, Jun; Brown, John W; Frankel, Steven H

    2010-01-01

    Objectives In a univentricular Fontan circulation, modest augmentation of existing cavopulmonary pressure head (2–5 mmHg) would reduce systemic venous pressure, increase ventricular filling, and thus, substantially improve circulatory status. An ideal means of providing mechanical cavopulmonary support does not exist. We hypothesized that a viscous impeller pump, based on the von Kármán viscous pump principle, is optimal for this role. Methods A 3-dimensional computational model of the total cavopulmonary connection was created. The impeller was represented as a smooth 2-sided conical actuator disk with rotation in the vena caval axis. Flow was modeled under 3 conditions: 1) passive flow with no disc; 2) passive flow with a non-rotating disk, and 3) induced flow with disc rotation (0–5K rpm). Flow patterns and hydraulic performance were examined for each case. Hydraulic performance for a vaned impeller was assessed by measuring pressure rise and induced flow over 0–7K rpm in a laboratory mock loop. Results A nonrotating actuator disc stabilizes cavopulmonary flow, reducing power loss by 88%. Disk rotation (from baseline dynamic flow of 4.4 L/min) resulted in a pressure rise of 0.03 mmHg. A further increase of pressure of 5–20 mmHg and 0–5 L/min flow were obtained with a vaned impeller at 0–7K rpm in a laboratory mock loop. Conclusions A single viscous impeller pump stabilizes and augments cavopulmonary flow in 4 directions, in the desired pressure range, without venous pathway obstruction. It applies to the existing staged protocol as a temporary bridge-to-recovery or –transplant in established univentricular Fontan circulations. It may also enable compressed palliation of single ventricle without need for intermediary surgical staging or use of a systemic-to-pulmonary arterial shunt. PMID:20561640

  3. Performance evaluation of a pediatric viscous impeller pump for Fontan cavopulmonary assist

    PubMed Central

    Giridharan, GA; Koenig, SC; Kennington, J; Sobieski, MA; Chen, J; Frankel, SH; Rodefeld, MD

    2012-01-01

    Purpose The anatomic and physiologic constraints for pediatric cavopulmonary assist differ markedly from adult Fontan circulations due to smaller vessel sizes and risk of elevated pulmonary resistance. In this study, hemodynamic and hemolysis performance capability of a catheter-based viscous impeller pump (VIP) to power the Fontan circulation is assessed at a pediatric scale (~15 kg) and performance range (0-30 mmHg). Methods Computer simulation and mock circulation studies were conducted to assess the hydraulic performance, acute hemodynamic response to different levels VIP support, and the potential for vena cavae collapse. Computational fluid dynamics (CFD) simulations were used to estimate VIP hydraulic performance, shear rates, and potential for hemolysis. Hemolysis was quantified in a mock loop with fresh bovine blood. Results A VIP augmented 4-way total cavopulmonary connection flow at pediatric scales and restored systemic pressures and flows to biventricular values, without causing flow obstruction or suction. VIP generated flows up to 4.1 L/min and pressure heads of up to 38 mmHg at 11,000 rpm. Maximal shear rate was 160 Pa, predicting low hemolysis risk. Observed hemolysis was low with plasma free hemoglobin of 11.4 mg/dL/hr. Conclusions A VIP will augment Fontan cavopulmonary flow in the proper pressure and flow ranges, with low hemolysis risk under more stringent pediatric scale and physiology compared to adult scale. This technology may be developed to simultaneously reduce systemic venous pressure and improve cardiac output after stage-2 or -3 Fontan repair. It may serve to compress surgical staging, lessening the pathophysiologic burden of repair. PMID:22421403

  4. Rotordynamic forces on centrifugal pump impellers

    NASA Technical Reports Server (NTRS)

    Franz, R.; Arndt, N.; Caughey, T. K.; Brennen, C. E.; Acosta, A. J.

    1987-01-01

    The asymmetric flow around an impeller in a volute exerts a force upon the impeller. To study the rotordynamic force on an impeller which is vibrating around its machine axis of rotation, the impeller, mounted on a dynamometer, is made to whirl in a circular orbit within the volute. The measured force is expressed as the sum of a steady radial force and an unsteady force due to the eccentric motion of the impeller. These forces were measured in separate tests on a centrifugal pump with radically increased shroud clearance, a two-dimensional impeller, and an impeller with an inducer, the impeller of the HPOTP (High Pressure Oxygen Turbopump) of the SSME (Space Shuttle Main Engine). In each case, a destabilizing force was observed over a region of positive whirl.

  5. Trim or Replace Impellers on Oversized Pumps

    SciTech Connect

    Not Available

    2006-09-01

    One in a series of tip sheets to help manufacturers optimize their industrial pumping systems. As a result of conservative engineering practices, pumps are often substantially larger than they need to be for an industrial plant's process requirements. Centrifugal pumps can often be oversized because of ''rounding up'', trying to accommodate gradual increases in pipe surface roughness and flow resistance over time, or anticipating future plant capacity expansions. In addition, the plant's pumping requirements might not have been clearly defined during the design phase. Because of this conservative approach, pumps can have operating points completely different from their design points. The pump head is often less than expected, while the flow rate is greater. This can cause cavitation and waste energy as the flow rate typically must be regulated with bypass or throttle control. Oversized and throttled pumps that produce excess pressure are excellent candidates for impeller replacement or ''trimming'', to save energy and reduce costs. Trimming involves machining the impeller to reduce its diameter. Trimming should be limited to about 75% of a pump's maximum impeller diameter, because excessive trimming can result in a mismatched impeller and casing. As the impeller diameter decreases, added clearance between the impeller and the fixed pump casing increases internal flow recirculation, causes head loss, and lowers pumping efficiency. For manufacturing standardization purposes, pump casings and shafts are designed to accommodate impellers in a range of sizes. Many pump manufacturers provide pump performance curves that indicate how various models will perform with different impeller diameters or trims. The impeller should not be trimmed any smaller than the minimum diameter shown on the curve. Net positive suction head requirements (NPSHR) usually decrease at lower flow rates and can increase at the higher end of the pump head curve. The NPSHR at a given flow rate will normally be greater with a smaller impeller, but engineers should consult with the pump manufacturer to determine variations in NPSHR before trimming the impeller. Manufacturers can often provide trim correction charts based on historical test data.

  6. High Head Unshrouded Impeller Pump Stage Technology

    NASA Technical Reports Server (NTRS)

    Williams, Robert W.; Skelley, Stephen E.; Stewart, Eric T.; Droege, Alan R.; Prueger, George H.; Chen, Wei-Chung; Williams, Morgan; Turner, James E. (Technical Monitor)

    2000-01-01

    A team of engineers at NASA/MSFC and Boeing, Rocketdyne division, are developing unshrouded impeller technologies that will increase payload and decrease cost of future reusable launch vehicles. Using the latest analytical techniques and experimental data, a two-stage unshrouded fuel pump is being designed that will meet the performance requirements of a three-stage shrouded pump. Benefits of the new pump include lower manufacturing costs, reduced weight, and increased payload to orbit.

  7. Some unsteady fluid forces on pump impellers

    NASA Technical Reports Server (NTRS)

    Miskovish, R. S.; Brennen, C. E.

    1992-01-01

    Special analyses of all the forces and moments acting on a typical centrifugal pump impeller/volute combination are presented. These exhibit shaft frequencies, blade passing frequencies, and beat frequencies associated with a whirl motion imposed on the shaft in order to measure rotordynamic forces. Among other features the unsteady thrust was found to contain a surprisingly large blade passing harmonic. While previous studies have explored the magnitudes of the steady fluid-induced radial forces and the fluid-induced rotordynamic forces for this typical centrifugal pump impeller/volute combination, this paper presents information on the steady bending moments and rotordynamic moments due to the fluid flow. These imply certain axial locations for the lines of action of the radial and rotordynamic forces. Data on the lines of action are presented and allow inferences on the sources of the forces.

  8. Viscous flow prediction within a centrifugal impeller 

    E-print Network

    Wohlschlegel, David Hale

    1976-01-01

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

  9. Rotordynamic characteristics of a shrouded pump impeller

    E-print Network

    Abou-El-Kheir, Magdy Sobhy

    1991-01-01

    May 1991 Major Subject: Mechanical Engineering ROTORDYNAMIC CHARACTERISTICS OF A SHROUDED PUMP IMPELLER A Thesis by MAGDY SOBHY ABOU-EL-KHEIR Approved as to style and content by: ~i' g gwAcmwe. Erian Baskharone (Chair of Committee... finite element for the three ? dimensional domain discretization Distortion of the finite elements as a result of the rotor eccentricity 21 23 30 10. 12. Secondary/primary flow interaction at a reduced Reynolds number of 1. 88 x 10 Vector plot...

  10. Evaluation of floating impeller phenomena in a Gyro centrifugal pump.

    PubMed

    Nishimura, Ikuya; Ichikawa, S; Mikami, M; Ishitoya, H; Motomura, T; Kawamura, M; Linneweber, J; Glueck, J; Shinohara, T; Nosé, Y

    2013-01-01

    The Gyro centrifugal pump developed as a totally implantable artificial heart was designed with a free impeller, in which the rotational shaft (male bearing) of the impeller was completely separated from the female bearing. For this type of pump, it is very important to keep the proper magnet balance (impeller-magnet and actuator-magnet) in order to prevent thrombus formation and/or bearing wear. When the magnet balance is not proper, the impeller is jerked down into the bottom bearing. On the other hand, if magnet balance is proper, the impeller lifted off the bottom of the pump housing within a certain range of pumping conditions. In this study, this floating phenomenon was investigated in detail. The floating phenomenon was proved by observation of the impeller behavior using a transparent acrylic pump. The impeller floating phenomenon was mapped on a pump performance curve. The impeller floating phenomenon is affected by the magnet-magnet coupling distance and rotational speed of the impeller. In order to keep the proper magnet balance and to maintain the impeller floating phenomenon at the driving condition of right and left pump, the magnet-magnet coupling distance was altered by a spacer which was installed between the pump and actuator. It became clear that the same pump could handle different conditions (right and left ventricular assist), by just changing the thickness of the spacer. When magnet balance is proper, the floating impeller phenomenon occurs automatically in response to the impeller rev. It is called "the dynamic RPM suspension". PMID:23442236

  11. Origins of hydrodynamic forces on centrifugal pump impellers

    NASA Technical Reports Server (NTRS)

    Adkins, Douglas R.; Brennen, Christopher E.

    1987-01-01

    Hydrodynamic interactions that occur between a centrifugal pump impeller and volute are experimentally and theoretically investigated. The theoretical analysis considers the inability of the blades to perfectly guide the flow through the impeller, and also includes a quasi-one dimensional treatment of the flow in the volute. The disturbance at the impeller discharge and the resulting forces are determined by the theoretical model. The model is then extended to obtain the hydrodynamic force perturbations that are caused by the impeller whirling eccentrically in the volute. Under many operating conditions, these force perturbations were found to be destablizing. Comparisons are made between the theoretical model and the experimental measurements of pressure distributions and radial forces on the impeller. The theoretical model yields fairly accurate predictions of the radial forces caused by the flow through the impeller. However, it was found that the pressure acting on the front shroud of the impeller has a substantial effect on the destablizing hydrodynamic forces.

  12. Numerical simulation of flow in centrifugal pump with complex impeller

    NASA Astrophysics Data System (ADS)

    Cui, Bao-ling; Lin, Yong-gang; Jin, Ying-zi

    2011-03-01

    Based on the Navier-Stokes equations and the Spalart-Allmaras turbulence model, three dimensional turbulent flow fields in centrifugal pump with long-mid-short blade complex impeller are calculated and analyzed numerically. The relative velocity and pressure distributions in the flowpart are obtained. It is found that the flow in the passage of the complex impeller is unsymmetrical due to the joint action between volute and impeller. The back-flow region is at inlet of long-blade suction side, near middle part of long-blade pressure side and outlet of short-blade suction side. The flow near volute throat is affected greatly by volute. The relative velocity is large and it is easy to bring back flow at outlet of the complex impeller near volute throat. The static and total pressure rise uniformly from inlet to outlet in the impeller. At impeller outlet, the pressure periodically decreases from pressure side to suction side, and then the static pressure sharply rise near the throat. The experimental results show that the back flow in the impeller has an important influence on the performance of pump.

  13. Viscous pumping inspired by flexible propulsion.

    PubMed

    Arco, Roger M; Vélez-Cordero, J Rodrigo; Lauga, Eric; Zenit, Roberto

    2014-09-01

    Fluid-suspended microorganisms have evolved different swimming and feeding strategies in order to cope with an environment dominated by viscous effects. For instance, ciliated organisms rely on the collective motion of flexible appendages to move and feed. By performing a non-reciprocal motion, flexible filaments can produce a net propulsive force, or pump fluid, in the absence of inertia. Inspired by such a fundamental concept, we propose a strategy to produce macroscopic pumping and mixing in creeping flow. We measured experimentally the net motion of a Newtonian viscous fluid induced by the reciprocal motion of a flapper. When the flapper is rigid no net motion is induced. In contrast, when the flapper is made of a flexible material, a net fluid pumping is measured. We quantify the effectiveness of this pumping strategy and show that optimal pumping is achieved when the length of the flapper is on the same order as the elasto-hydrodynamic penetration length. We finally discuss the possible applications of flexible impellers in mixing operations at low Reynolds numbers. PMID:24667497

  14. Cavitating flow investigation inside centrifugal impellers for a condensate pump

    NASA Astrophysics Data System (ADS)

    Wei, W.; Luo, X. W.; Ji, B.; Zhuang, B. T.; Xu, H. Y.

    2012-11-01

    In order to investigate the effect of blade inlet angle on centrifugal pump cavitation performance, numerical simulation of cavitating turbulent flow is conducted for a condensate pump with different impellers based on SST k-? turbulence model and a mixture cavitation model. The results indicate that for a condensate pump having meridional section with larger area at blade leading edge compared with conventional pumps, the reverse flows inside the blade-to-blade channels are not negligible. It is noted that large incidence at blade leading edge is helpful to improve the cavitation performance for the pump. The possible reason may be the growth of cavities inside the impeller has less influence on the flow in the channel between two neighboring blades. Further, uniform incidence angle along the blade leading edge is preferable for the improvement of cavitation performance.

  15. Laser velocimetry study of the flow field in a centrifugal pump with a shrouded impeller 

    E-print Network

    Moran, Michael Kevin

    1994-01-01

    to the pump Power loss calculated from the leakage flow Hydraulic power of the water Stagnation pressure Flow rate through the pump Leakage flow rate Nondimensional flow coefficient Radius of the impeller Radial distance from the impeller eye Beam... fluctuations parallel to the flow Absolute velocity Radial component of the absolute velocity Average radial velocity Radial velocity at the impeller discharge Tangential component of the absolute velocity V~. . z v Tangential velocity at the impeller...

  16. Research on performance of centrifugal pump with different-type open impeller

    NASA Astrophysics Data System (ADS)

    Cui, Baoling; Chen, Desheng; Wang, Canfei; Zhu, Zuchao; Jin, Yingzi; Jin, Yuzhen

    2013-12-01

    To investigate the influence of impeller type on the performance and inner flow of centrifugal pump, the numerical simulation and experimental research were carried out on the same centrifugal pump with straight-blade and curved-blade open impeller. Based on SIMPLEC algorithm, time-averaged N-S equation and the standard k-? turbulence model, the numerical results are obtained. The pressure distribution in the different type impellers is uniform, while the low pressure area in straight-blade inlet is larger. The vortexes in the passage of impeller exist in both cases. Relative to curved-blade impeller, there are larger vortexes in most of the flow passages except the passage near the tongue in straight-blade impeller. Also some small backflow regions are found at the blade inlet of two impellers. The characteristic curves achieved by numerical simulation basically agree with those by experiment, and straight-blade open impeller centrifugal pump has a better hydraulic performance.

  17. Inviscid-viscous interaction method for three-dimensional inverse design of centrifugal impellers

    Microsoft Academic Search

    M. Zangeneh

    1994-01-01

    A three-dimensional design method for the design of the blade geometry of centrifugal compressor impellers is presented. In this method the blade shape is computed for a specified circulation distribution, normal (or tangential) thickness distribution, and meridional geometry. As the blade shapes are computed by using an inviscid slip (or flow tangency) condition, the viscous effects are introduced indirectly by

  18. Pulsatile blood flow from impeller pump: a dream has come true.

    PubMed

    Qian, K X

    1994-10-01

    For decades many investigations have been made on producing a pulsatile blood flow with an impeller pump. It has been foiled because of excessive hemolysis. Other investigators foretold that a pulsatile centrifugal pump is impossible in the near future, without increasing the complexity of the system remarkably. The author has presevered in this study and made progress steadily. An axial pulsatile impeller pump with constant-rotating speed was developed, in which the impeller reciprocates along its axis while rotates. Meanwhile, a pulsatile implantable impeller centrifugal pump is now in animal surviving experimental stage. The pulsatility of the blood flow is achieved by changing the rotating speed of the impeller periodically, via introducing a square wave form voltage into the motor coil. The hemodynamic and physiological superiorities to both nonpulsatile impeller pump and diaphragm pump were demonstrated. The hematological and biochemical data indicated low hemolysis and thrombogenesis, low renal and heptic dysfunction. Furthermore, a pulsatile implantable impeller total heart has completed its acute biventricular assist animal experiments. This is an almost unique total heart at the present, it is driven by a single motor, the left and right pumps eject the blood simultaneously, and the volume equilibrium of both pumps is achieved naturally. The dream of producing a pulsatile blood flow with an impeller pump has come true. Doubtlessly, an impeller heart with simplicity, pulsatility, implantability, compatibility and reliability, will be a viable alternative to diaphragm heart, really. PMID:7782998

  19. Inviscid-viscous interaction method for three-dimensional inverse design of centrifugal impellers

    NASA Astrophysics Data System (ADS)

    Zangeneh, M.

    1994-04-01

    A three-dimensional design method for the design of the blade geometry of centrifugal compressor impellers is presented. In this method the blade shape is computed for a specified circulation distribution, normal (or tangential) thickness distribution, and meridional geometry. As the blade shapes are computed by using an inviscid slip (or flow tangency) condition, the viscous effects are introduced indirectly by using a viscous/inviscid procedure. The three-dimensional Navier-Stokes solver developed by Dawes is used as the viscous method. Two different approaches are described for incorporating the viscous effects into the inviscid design method. One method is based on the introduction of an aerodynamic blockage distribution throughout the meridional geometry, while in the other approach a vorticity term directly related to the entropy gradients in the machine is introduced. The method is applied to redesign the blade geometry of Eckardt's 30 deg backswept impeller as well as a generic high pressure ratio (transonic) impeller. The results indicate that the entropy gradient approach can fairly accurately represent the viscous effects in the machine.

  20. Impeller behavior and displacement of the VentrAssist implantable rotary blood pump.

    PubMed

    Chung, Michael K H; Zhang, Nong; Tansley, Geoff D; Woodard, John C

    2004-03-01

    The VentrAssist implantable rotary blood pump, intended for long-term ventricular assist, is under development and is currently being tested for its rotor-dynamic stability. The pump is of the centrifugal type and consists of a shaftless impeller, also acting as the rotor of the brushless DC motor. The impeller remains passively suspended in the pump cavity by hydrodynamic forces, resulting from the small clearances between the impeller outside surfaces and the pump cavity. In the older version of the pump tested, these small clearances range from approximately 50 microm to 230 microm; the displacement of the impeller relative to the pump cavity is unknown in use. This article presents two experiments: the first measured displacement of the impeller using eddy-current proximity sensors and laser proximity sensors. The second experiment used Hall-effect proximity sensors to measure the displacement of the impeller relative to the pump cavity. All transducers were calibrated prior to commencement of the experiments. Voltage output from the transducers was converted into impeller movement in five degrees of freedom (x, y, z, theta(x), and theta(y)). The sixth degree of freedom, the rotation about the impeller axis (theta(z)), was determined by the commutation performed by the motor controller. The impeller displacement was found to be within the acceptable range of 8 micro m to 222 microm, avoiding blood damage and contact between the impeller and cavity walls. Thus the impeller was hydrodynamically suspended within the pump cavity and results were typical of centrifugal pump behavior. This research will be the basis for further investigation into the stiffness and damping coefficient of the pump's hydrodynamic bearing. PMID:15046628

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

    NASA Astrophysics Data System (ADS)

    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.

  2. Evaluation of subgrid-scale models in large-eddy simulations of turbulent flow in a centrifugal pump impeller

    NASA Astrophysics Data System (ADS)

    Yang, Zhengjun; Wang, Fujun; Zhou, Peijian

    2012-09-01

    The current research of large eddy simulation (LES) of turbulent flow in pumps mainly concentrates in applying conventional subgrid-scale (SGS) model to simulate turbulent flow, which aims at obtaining the flow field in pump. The selection of SGS model is usually not considered seriously, so the accuracy and efficiency of the simulation cannot be ensured. Three SGS models including Smagorinsky-Lilly model, dynamic Smagorinsky model and dynamic mixed model are comparably studied by using the commercial CFD code Fluent combined with its user define function. The simulations are performed for the turbulent flow in a centrifugal pump impeller. The simulation results indicate that the mean flows predicted by the three SGS models agree well with the experimental data obtained from the test that detailed measurements of the flow inside the rotating passages of a six-bladed shrouded centrifugal pump impeller performed using particle image velocimetry (PIV) and laser Doppler velocimetry (LDV). The comparable results show that dynamic mixed model gives the most accurate results for mean flow in the centrifugal pump impeller. The SGS stress of dynamic mixed model is decompose into the scale similar part and the eddy viscous part. The scale similar part of SGS stress plays a significant role in high curvature regions, such as the leading edge and training edge of pump blade. It is also found that the dynamic mixed model is more adaptive to compute turbulence in the pump impeller. The research results presented is useful to improve the computational accuracy and efficiency of LES for centrifugal pumps, and provide important reference for carrying out simulation in similar fluid machineries.

  3. Design Optimization of Mixed-flow Pump Impellers and Diffusers in a Fixed Meridional Shape

    Microsoft Academic Search

    Sung Kim; Young-Seok Choi; Kyoung-Yong Lee

    2010-01-01

    In this paper, design optimization for mixed-flow pump impellers and diffusers has been studied by using a commercial CFD code and DOE(design of experiments). We also discussed how to improve the performance of the mixed-flow pump by designing the impeller and diffuser in the mixed-flow pump. Geometric design variables were defined by the vane plane development which indicates the blade-angle

  4. Unsteady diffuser vane pressure and impeller wake measurements in a centrifugal pump

    NASA Technical Reports Server (NTRS)

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

    1987-01-01

    Unsteady surface pressure measurements on a vaned diffuser of a centrifugal pump, and wake measurements of the flow exiting a centrifugal impeller into a vaneless diffuser are presented. Frequency spectra and ensemble averages are given for the unsteady measurements. Two different impellers were used, the pump impeller of the HPOTP (High Pressure Oxygen Turbopump) of the SSME (Space Shuttle Main Engine) and a two-dimensional impeller. The magnitude of the unsteady total pressure measured in the stationary frame at the impeller exit was found to be of the same order of magnitude as the total pressure rise across the pump. The magnitude of the unsteady diffuser vane pressures was observed to be significantly different on suction and pressure side of the vane, attaining its largest value on the suction side the leading edge while decreasing along the vane.

  5. CFD application in optimization improvement design of a low specific speed centrifugal pump impeller

    Microsoft Academic Search

    Guo Jin-jin; Zheng Qing-chun; Feng Xin-liang

    2010-01-01

    There are some problems of hydraulic performance in the low specific speed centrifugal pump, such as small capacity, low efficiency. In this paper, the long-short blade method and enlarging flow method is applied to optimize the impeller. In design of impeller optimizing, author uses CFD technology to predict model performance, analyzes the test results, finally gets the best parameters combination

  6. A Navier-Stokes solution of the three-dimensional viscous compressible flow in a centrifugal compressor impeller

    NASA Technical Reports Server (NTRS)

    Harp, J. L., Jr.

    1977-01-01

    A two-dimensional time-dependent computer code was utilized to calculate the three-dimensional steady flow within the impeller blading. The numerical method is an explicit time marching scheme in two spatial dimensions. Initially, an inviscid solution is generated on the hub blade-to-blade surface by the method of Katsanis and McNally (1973). Starting with the known inviscid solution, the viscous effects are calculated through iteration. The approach makes it possible to take into account principal impeller fluid-mechanical effects. It is pointed out that the second iterate provides a complete solution to the three-dimensional, compressible, Navier-Stokes equations for flow in a centrifugal impeller. The problems investigated are related to the study of a radial impeller and a backswept impeller.

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

    NASA Astrophysics Data System (ADS)

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

    2015-05-01

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

  8. Compressibility effects on rotor forces in the leakage path between a shrouded pump impeller and its housing 

    E-print Network

    Cao, Nhai The

    1993-01-01

    path between an impeller shroud and its housing is presented in this paper. Three governing equations consisting of continuity, path- momentum, and circumferential-momentum equations were developed to describe the leakage path inside a pump impeller.... Radial displacement perturbations were used to solve for radial and circumferential force coefficients. In addition, impeller-discharge pressure disturbances were used to obtain pressure oscillation responses due to precessing impeller pressure wave...

  9. Numerical prediction and experimental evaluation of cavitation inception on centrifugal pump impellers

    SciTech Connect

    Ardizzon, G.; Pavesi, G. [Univ. of Padua (Italy)

    1994-12-31

    A procedure, based on a simplified Quasi 3-D flow analysis, is proposed to predict the cavitation inception on centrifugal pump impellers. The effects due to the impeller geometry and the incidence angle are described and discussed. The merits of the present formulation are demonstrated by comparison with measured values as well as with other published relations. Design and off-design NPSH values predicted with the procedure here proposed appears to be in close agreement with experimental observations.

  10. Experimental research and numerical simulation on impeller exit flow field of bulb tubular pump

    NASA Astrophysics Data System (ADS)

    Jin, Y.; Liu, C.; Zhou, J. R.

    2012-11-01

    Three dimensional Laser Doppler Velocimetry (3D-LDV) technique was used to measure the impeller exit flow field of bulb tubular pump, the average velocity distribution of the exit section was obtained, and the energy performance of bulb tubular pump was obtained by model test. The flow field of tubular pump also simulated by CFD based on Navier-Stokes equations and RNG k-epsilon model. The calculated performance curve was consistent with the model test results, and the calculated velocities of impeller exit compared with the LDV measurement results, it was shown that the distribution of circumferential velocity and axial velocity were close to each other, but the radial velocity deviation between the LDV results and the CFD ones was obviously, the reasons of deviation were analyzed. The experimental results can provide the references for the impeller and diffuser design of tubular pumps, it also can improve the accuracy of calculation and perfect simulation.

  11. Force and moment rotordynamic coefficients for pump-impeller shroud surfaces

    NASA Technical Reports Server (NTRS)

    Childs, Dara W.

    1987-01-01

    Governing equations of motion are derived for a bulk-flow model of the leakage path between an impeller shroud and a pump housing. The governing equations consist of a path-momentum, a circumferential - momentum, and a continuity equation. The fluid annulus between the impeller shroud and pump housing is assumed to be circumferentially symmetric when the impeller is centered; i.e., the clearance can vary along the pump axis but does not vary in the circumferential direction. A perturbation expansion of the governing equations in the eccentricity ratio yields a set of zeroth and first-order governing equations. The zeroth-order equations define the leaking rate and the circumferential and path velocity distributions and pressure distributions for a centered impeller position. The first-order equations define the perturbations in the velocity and pressure distributions due to either a radial-displacement perturbation or a tilt perturbation of the impeller. Integration of the perturbed pressure and shear-stress distribution acting on the rotor yields the reaction forces and moments acting on the impeller face.

  12. Circulating pump impeller: Presbyterian Intercommunity Hospital, Klamath Falls, Oregon, geothermal heating system. Failure analysis report

    Microsoft Academic Search

    D. A. Mitchell; P. F. Ellis

    1979-01-01

    The Presbyterian Intercommunity Hospital located in Klamath Falls, Oregon utilizes geothermal fluid pumped from its own well to provide space heat and domestic hot water. During an inspection of the heating system after a chemical cleaning of the heat exchangers, the circulating pump was dismantled to replace its seals which were found to be leaking. At that time, the impeller

  13. Pump impeller-shroud leakage path forces: their effect on a Jeffcott rotor 

    E-print Network

    Williams, James Philip

    1988-01-01

    PUMP IMPELLER-SHROUD LEAKAGE PATH FORCES: THEIR EFFECT ON A JEFFCOTI' ROTOR A Thesis by JAMES PHILIP WILLIAMS Submitted to the Graduate CoHege of Texas A&M University in partial fulfillment of the requirements for the degree of MASTER... OF SCIENCE May 1988 Major Subject: Mechanical Engineering PUMP IMPELLER-SHROUD LEAKAGE PATH FORCES: THEIR EFFECT ON A JEFFCOTT ROTOR A Thesis by JAMES PHILIP WILLIAMS Approved as to style and content by: Dara Childs (Chair of Committee) Ricardo L...

  14. Permanent magnetic-levitation of rotating impeller: a decisive breakthrough in the centrifugal pump.

    PubMed

    Qian, K X; Zeng, P; Ru, W M; Yuan, H Y; Feng, Z G; Li, L

    2002-01-01

    Magnetic bearings have no mechanical contact between the rotor and stator, and a rotary pump with magnetic bearings therefore has no mechanical wear and thrombosis. The magnetic bearings available, however, contain electromagnets, are complicated to control and have high energy consumption. Therefore, it is difficult to apply an electromagnetic bearing to a rotary pump without disturbing its simplicity, reliability and ability to be implanted. The authors have developed a levitated impeller pump using only permanent magnets. The rotor is supported by permanent radial magnetic forces. The impeller is fixed on one side of the rotor; on the other side the rotor magnets are mounted. Opposite these rotor magents, a driving magnet is fastened to the motor axis. Thereafter, the motor drives the rotor via magnetic coupling. In laboratory tests with saline, where the rotor is still or rotates at under 4,000 rpm, the rotor magnets have one point in contact axially with a spacer between the rotor magnets and the driving magnets. The contacting point is located in the center of the rotor. As the rotating speed increases gradually to more than 4000 rpm, the rotor will disaffiliate from the stator axially, and become fully levitated. Since the axial levitation is produced by hydraulic force and the rotor magnets have a giro-effect, the rotor rotates very stably during levitation. As a left ventricular assist device, the pump works in a rotating speed range of 5,000-8,000 rpm, and the levitation of the impeller is assured by use of the pump. The permanent maglev impeller pump retains the advantages of the rotary pump but overcomes the disadvantages of the leviated pump with electromagnetic-bearing, and has met with most requirements of artificial heart blood pumps, thus promising to have more applications than previously. PMID:11924845

  15. Investigation of CFD calculation method of a centrifugal pump with unshrouded impeller

    NASA Astrophysics Data System (ADS)

    Wu, Dazhuan; Yang, Shuai; Xu, Binjie; Liu, Qiaoling; Wu, Peng; Wang, Leqin

    2014-03-01

    Currently, relatively large errors are found in numerical results in some low-specific-speed centrifugal pumps with unshrouded impeller because the effect of clearances and holes are not accurately modeled. Establishing an accurate analytical model to improve performance prediction accuracy is therefore necessary. In this paper, a three-dimensional numerical simulation is conducted to predict the performance of a low-specific-speed centrifugal pump, and the modeling, numerical scheme, and turbulent selection methods are discussed. The pump performance is tested in a model pump test bench, and flow rate, head, power and efficiency of the pump are obtained. The effect of taking into consideration the back-out vane passage, clearance, and balance holes is analyzed by comparing it with experimental results, and the performance prediction methods are validated by experiments. The analysis results show that the pump performance can be accurately predicted by the improved method. Ignoring the back-out vane passage in the calculation model of unshrouded impeller is found to generate better numerical results. Further, the calculation model with the clearances and balance holes can obviously enhance the numerical accuracy. The application of disconnect interface can reduce meshing difficulty but increase the calculation error at the off-design operating point at the same time. Compared with the standard k-?, renormalization group k-?, and Spalart-Allmars models, the Realizable k-? model demonstrates the fastest convergent speed and the highest precision for the unshrouded impeller flow simulation. The proposed modeling and numerical simulation methods can improve the performance prediction accuracy of the low-specific-speed centrifugal pumps, and the modeling method is especially suitable for the centrifugal pump with unshrouded impeller.

  16. A fast numerical method for flow analysis and blade design in centrifugal pump impellers

    Microsoft Academic Search

    John S. Anagnostopoulos

    2009-01-01

    A numerical methodology is developed to simulate the turbulent flow in a 2-dimensional centrifugal pump impeller and to compute the characteristic performance curves of the entire pump. The flow domain is discretized with a polar, Cartesian mesh and the Reynolds-averaged Navier–Stokes (RANS) equations are solved with the control volume approach and the k–? turbulence model. Advanced numerical techniques for adaptive

  17. Analysis on the influence of the pump start transient performance with different inertia impeller

    NASA Astrophysics Data System (ADS)

    Tang, Y.; Cheng, J.; Liu, E. H.; Tang, L. D.

    2012-11-01

    Centrifugal pump start-up time is very short, in the boot process, the instantaneous head and flow will have an impact role to the pipeline, and however the moment of inertia is one of the main factors affecting centrifugal pump boot acceleration. We analyzed the pump start-up transient characteristics with the different moment of inertia of the impeller corresponding to the different materials, there are three different moment of inertia of the impeller have been selected. At first, we use the "Flowmaster" fluid system simulation software do the outer characteristics simulation to the selected-model, get the time - flow and the time - speed curve. Then, do the experiments research in the process when pump start-up, and compare with the simulation result. At last use the outer characteristics simulation result as the boundary, using the ANASYS CFX software do the transient simulation to the three groups with different inertia pump impeller, and draw the pressure distribution picture. In according to the analysis, we can confirm that the impact of inertia is one of the factors in the stability during the pump star, and we can get that the greater moment of inertia, the longer the boot stable. We also can get that combined Flowmaster with ANSYS can solved engineering practice problem in fluid system conveniently, and take it easy to solve the similar problem.

  18. Experimental study of unsteady hydrodynamic force matrices on whirling centrifugal pump impellers. Ph.D. Thesis

    NASA Technical Reports Server (NTRS)

    Belgacem, Jery

    1986-01-01

    An experimental facility was constructed and instrumented. A set of centrifugal flow pumps whose impellers were made to follow a controlled circular whirl motion were studied. The aim was to characterize the steady and unsteady fluid forces measured on the impeller under various pump operating conditions. The postulation was that the unsteady lateral forces result from interactions between the impeller and the surrounding diffuser and/or volute (via the working fluid), and that under certain flow regimes these forces can drive unstable lateral motions of the pump rotor. The lateral hydrodynamic forces were decomposed into their steady and unsteady parts, the latter being further expressed in terms of a generalized fluid stiffness matrix. Conclusions regarding the effect of impeller geometry could not be reached given the similarity of the tested designs. However, other results on phenomena such as skin friction and leakage flow are presented. Some of the findings are compared to experimental and theoretical data from other sources. Finally, the rotordynamic consequences of the results are discussed as the present data were applied to the case of the Space Shuttle Main Engine (SSME) High Pressure Oxidizer Turbopump (HPOTP).

  19. Numerical flow-field analysis and design optimization of a high-energy first-stage centrifugal pump impeller

    Microsoft Academic Search

    F. C. Visser; R. J. H. Dijkers; J. G. H. op de Woerd

    2000-01-01

    .   Described is the numerical flow-field analysis and design optimization of the first-stage impellers of a so-called high-energy\\u000a centrifugal pump having two single-suction first-stage impellers and one double-suction second stage impeller. This study\\u000a has been carried out with the aid of three-dimensional computational-fluid-dynamics calculations, employing the potential-flow\\u000a approximation of the governing equations. The study was conducted because the first-stage impellers

  20. ON THE PARTICLE TRAJECTORIES IN DREDGE PUMP IMPELLERS

    Microsoft Academic Search

    C. F. Hofstra; C. van Rhee; S. A. Miedema; A. M. Talmon

    In dredging, specific knowledge of particle flow through pipes and pumps is required so that the design of the various components can be optimized for the requirements of mixture flow. In the absence of theoretical knowledge, experimental results are used to predict losses in pipelines and the performance of pumps. This approach, while sufficient for application in general, is not

  1. Rotordynamic coefficients for shrouded pump impellers: comparisons between a new computer solution and test results

    E-print Network

    Daniel, Arul Sathyasundar

    1992-01-01

    the shroud- to-housing leakage path. Many studies related to this field have been applied to the space shuttle main engine turbopumps. Of importance is the vibrations problem encountered in rotary systems in which the rotor axis tends to whirl around... would be valuable for the model to be applied to the space shuttle- main engine turbopumps. 42 REFERENCES Adkins, D. E. , 1986, "Analysis of Hydrodynamic Forces on Centrifugal Pump Impellers, " Ph. D Thesis, California Institute of Technology...

  2. On the use of a three-dimensional Navier-Stokes solver for rocket engine pump impeller design

    NASA Technical Reports Server (NTRS)

    Chen, Wei-Chung; Prueger, George H.; Chan, Daniel C.; Eastland, Anthony H.

    1992-01-01

    A 3D Reynolds-averaged Navier-Stokes Solver and a Fast Grid Generator (FGG), developed specially for centrifugal impeller design, were incorporated into the pump impeller design process. The impeller performance from the CFD analysis was compared to one-dimensional prediction. Both analyses showed good agreement of the impeller hydraulic efficiency, 94.5 percent, but with an 8 percent discrepancy of Euler head prediction. The impeller blade angle, discharge hub to shroud width, axial length and blade stacking were systematically changed to achieve an optimum impeller design. Impeller overall efficiency, loss distribution, hub-to-tip flow angle distortion and blade-to-blade flow angle change are among those criteria used to evaluate impeller performance. Two grid sizes, one with 10 K grid points and one with 80 K grid points were used to evaluate grid dependency issues. The effects of grid resolution on the accuracy and turnaround time are discussed. In conclusion, it is demonstrated that CFD can be effectively used for design and optimization of rocket engine pump components.

  3. Hydraulic optimization of a double-channel pump's impeller based on multi-objective genetic algorithm

    NASA Astrophysics Data System (ADS)

    Zhao, Binjuan; Wang, Yu; Chen, Huilong; Qiu, Jing; Hou, Duohua

    2015-03-01

    Computational fluid dynamics (CFD) can give a lot of potentially very useful information for hydraulic optimization design of pumps, however, it cannot directly state what kind of modification should be made to improve such hydrodynamic performance. In this paper, a more convenient and effective approach is proposed by combined using of CFD, multi-objective genetic algorithm (MOGA) and artificial neural networks (ANN) for a double-channel pump's impeller, with maximum head and efficiency set as optimization objectives, four key geometrical parameters including inlet diameter, outlet diameter, exit width and midline wrap angle chosen as optimization parameters. Firstly, a multi-fidelity fitness assignment system in which fitness of impellers serving as training and comparison samples for ANN is evaluated by CFD, meanwhile fitness of impellers generated by MOGA is evaluated by ANN, is established and dramatically reduces the computational expense. Then, a modified MOGA optimization process, in which selection is performed independently in two sub-populations according to two optimization objectives, crossover and mutation is performed afterword in the merged population, is developed to ensure the global optimal solution to be found. Finally, Pareto optimal frontier is found after 500 steps of iterations, and two optimal design schemes are chosen according to the design requirements. The preliminary and optimal design schemes are compared, and the comparing results show that hydraulic performances of both pumps 1 and 2 are improved, with the head and efficiency of pump 1 increased by 5.7% and 5.2%, respectively in the design working conditions, meanwhile shaft power decreased in all working conditions, the head and efficiency of pump 2 increased by 11.7% and 5.9%, respectively while shaft power increased by 5.5%. Inner flow field analyses also show that the backflow phenomenon significantly diminishes at the entrance of the optimal impellers 1 and 2, both the area of vortex and intensity of vortex decreases in the whole flow channel. This paper provides a promising tool to solve the hydraulic optimization problem of pumps' impellers.

  4. Experiments on the unsteady flow field and noise generation in a centrifugal pump impeller

    NASA Astrophysics Data System (ADS)

    Choi, Jong-Soo; McLaughlin, Dennis K.; Thompson, Donald E.

    2003-06-01

    This paper reports on an experimental investigation of large-scale flowfield instabilities in a pump rotor and the process of noise generation by these instabilities. Measurements of the fluctuating components of velocity and surface pressure were made with hot-wire probes and surface mounted pressure transducers on a seven bladed back swept centrifugal water pump impeller operating with air as the working fluid. The impeller was operated without a volute or scroll diffuser, thereby eliminating any sound generation from pressure fluctuations on the volute cutoff. Thus the study focused on flow field and noise components other than the blade passage frequency (and its harmonics). The primary goal of the study was to provide fundamental information on the unsteady flow processes, particularly those associated with the noise generation in the device. It was further anticipated that detailed flow measurements would be useful for the validation of future computational simulations. The measured data at the discharge show a jet-wake type of flow pattern which results in a strong vorticity field. The flow with high velocity found on the pressure side of the impeller tends to move to the low-pressure region present at the suction side of the passage as a form of roll-up around the blade trailing edge. This motion causes an unsteady flow separation at the suction side of the blade and consequently disturbs the flow in the adjacent passage. By interacting with the impeller blades near the trailing edges, this instability flow causes a periodic pressure fluctuation on the blade surface and generates noise by a trailing edge generation mechanism. The spectrum of surface pressure measured at the trailing edge of each blade reveals a cluster of peaks which were identified with azimuthal mode numbers. The correlation between the acoustic farfield pressure and the surface pressure on the impeller blade has proven that the azimuthal modes synchronized with the number of impeller blades generate noise much more efficiently than the other modes. The paper also clarifies the correlation between unsteady flowfield measurements, in both impeller and laboratory co-ordinates, with the radiated noise properties. Thus some light is shed on the noise generation mechanisms of this particular device.

  5. Controlled pitch-adjustment of impeller blades for an intravascular blood pump.

    PubMed

    Throckmorton, Amy L; Sciolino, Michael G; Downs, Emily A; Saxman, Robert S; López-Isaza, Sergio; Moskowitz, William B

    2012-01-01

    Thousands of mechanical blood pumps are currently providing circulatory support, and the incidence of their use continues to increase each year. As the use of blood pumps becomes more pervasive in the treatment of those patients with congestive heart failure, critical advances in design features to address known limitations and the integration of novel technologies become more imperative. To advance the current state-of-the-art in blood pump design, this study investigates the inclusion of pitch-adjusting blade features in intravascular blood pumps as a means to increase energy transfer; an approach not explored to date. A flexible impeller prototype was constructed with a configuration to allow for a variable range of twisted blade geometries of 60-250°. Hydraulic experiments using a blood analog fluid were conducted to characterize the pressure-flow performance for each of these twisted positions. The flexible, twisted impeller was able to produce 1-25 mmHg for 0.5-4 L/min at rotational speeds of 5,000-8,000 RPM. For a given twisted position, the pressure rise was found to decrease as a function of increasing flow rate, as expected. Generally, a steady increase in the pressure rise was observed as a function of higher twisted degrees for a constant rotational speed. Higher rotational speeds for a specific twisted impeller configuration resulted in a more substantial pressure generation. The findings of this study support the continued exploration of this unique design approach in the development of intravascular blood pumps. PMID:22691415

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

    NASA Astrophysics Data System (ADS)

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

    2013-01-01

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

  7. Compressibility effects on rotor forces in the leakage path between a shrouded pump impeller and its housing

    Microsoft Academic Search

    Nhai The Cao

    1993-01-01

    A modified approach to Childs' previous work on fluid-structure interaction forces in the leakage path between an impeller shroud and its housing is presented in this paper. Three governing equations consisting of continuity, path-momentum, and circumferential-momentum equations were developed to describe the leakage path inside a pump impeller. Radial displacement perturbations were used to solve for radial and circumferential force

  8. Modal behavior of a reduced scale pump turbine impeller. Part II: Numerical simulation

    NASA Astrophysics Data System (ADS)

    Valero, C.; Huang, X.; Egusquiza, E.; Farhat, M.; Avellan, F.

    2010-08-01

    A numerical simulation has been carried out to analyze the modal behavior of a reduced scale pump-turbine impeller. The simulation has been done using FEM method, in air and in water. The same boundary conditions than in the experiment were considered: free body in air and free body submerged in a reservoir of water. A sensitivity analysis to determine the influence of the number of elements was done. The influence of the input parameters was also taken into account. Finally, a mesh with 165000 elements for the impeller in air and of 508676 for the impeller in water was used. The results obtained with the simulation have been compared with the experimental ones (paper 1). Both the natural frequency values and the mode-shapes were compared. The numerical results showed small deviation from experiment in the first modes in modes with low modal density. In some coupled modes been found. With the updated model the mode-shapes have been analyzed. Some modes with high modal density have been found. As indicated in the experiment, the effect of the added mass reduces the natural frequencies and also changes the characteristics of the coupled modes.

  9. Multicondition Optimization and Experimental Measurements of a Double-Blade Centrifugal Pump Impeller.

    PubMed

    Liu, Houlin; Wang, Kai; Yuan, Shouqi; Tan, Minggao; Wang, Yong; Dong, Liang

    2013-01-01

    In order to improve internal unsteady flow in a double-blade centrifugal pump (DBCP), this study used major geometric parameters of the original design as the initial values, heads at three conditions (i.e., 80% design flow rate, 100% design flow rate, and 120% design flow rate) as the constraints conditions, and the maximum of weighted average efficiency at the three conditions as the objective function. An adaptive simulated annealing algorithm was selected to solve the energy performance calculation model and the supertransitive approximation method was applied to fix optimal weight factors of individual objectives. On the basis of hydraulic performance optimization, three-condition automatic computational fluid dynamics (CFD) optimization of impeller meridional plane for the DBCP was realized by means of Isight software integrated Pro/E, Gambit, and Fluent software. The shroud arc radii R0 and R1, shroud angle T1, hub arc radius R2, and hub angle T2 on the meridional plane were selected as the design variables and the maximum of weighted average hydraulic efficiency at the three conditions was chosen as the objective function. Performance characteristic test and particle image velocimetry (PIV) measurements of internal flow in the DBCP were conducted. Performance characteristic test results show that the weighted average efficiency of the impeller after the three-condition optimization has increased by 1.46% than that of original design. PIV measurements results show that vortex or recirculation phenomena in the impeller are distinctly improved under the three conditions. PMID:23917426

  10. Computational fluid dynamics model for predicting flow of viscous fluids in a large fermentor with hydrofoil flow impellers and internal cooling coils

    PubMed

    Kelly; Humphrey

    1998-03-01

    Considerable debate has occurred over the use of hydrofoil impellers in large-scale fermentors to improve mixing and mass transfer in highly viscous non-Newtonian systems. Using a computational fluid dynamics software package (Fluent, version 4.30) extensive calculations were performed to study the effect of impeller speed (70-130 rpm), broth rheology (value of power law flow behavior index from 0.2 to 0.6), and distance between the cooling coil bank and the fermentor wall (6-18 in.) on flow near the perimeter of a large (75-m3) fermentor equipped with A315 impellers. A quadratic model utilizing the data was developed in an attempt to correlate the effect of A315 impeller speed, power law flow behavior index, and distance between the cooling coil bank and the fermentor wall on the average axial velocity in the coil bank-wall region. The results suggest that there is a potential for slow or stagnant flow in the coil bank-wall region which could result in poor oxygen and heat transfer for highly viscous fermentations. The results also indicate that there is the potential for slow or stagnant flow in the region between the top impeller and the gas headspace when flow through the coil bank-wall region is slow. Finally, a simple guideline was developed to allow fermentor design engineers to predict the degree of flow behind a bank of helical cooling coils in a large fermentor with hydrofoil flow impellers. PMID:9548776

  11. Large Eddy Simulation for Flow Analysis in a Centrifugal Pump Impeller

    NASA Astrophysics Data System (ADS)

    Byskov, R. K.; Jacobsen, C. B.; Condra, T.; SØrensen, J. N.

    With the objective of gaining improvedinsight in the local flow behaviour and increasing the accuracy of numerical simulations the flow field in a centrifugal pump impeller has been investigated using LES. The effect of the SGS-scales have been modelled using a localised dynamic Smagorinsky model recently implemented in the commercial CFD code FINE/Turbo. Detailed flow structures are analysed at flow rates of 25 and 100 percent design load. Velocities predicted from LES and steady state RANS simulations are compared with PIV measurements, showing satisfactory agreement between LES and PIV.

  12. The rotordynamic forces on a centrifugal pump impeller in the presence of cavitation

    NASA Technical Reports Server (NTRS)

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

    1990-01-01

    Fluid-induced rotordynamic forces on a centrifugal pump impeller whirling along a trajectory eccentric to its undeflected position in the presence of cavitation were measured using the experimental facility described by Jery (1987). The force measured is a combination of a steady radial force due to the volute asymmetries and an unsteady force due to the eccentric motion of the rotor. It was found that, compared to the noncavitation condition, a cavitation corresponding to a head loss of 3 percent had little effect upon the unsteady force. However, a lesser degree of cavitation at the design point, was found to increase the destabilizing force for a particular set of whirl ratios.

  13. Some refinements of the theory of the viscous screw pump.

    NASA Technical Reports Server (NTRS)

    Elrod, H. G.

    1972-01-01

    Recently performed analysis for herringbone thrust bearings has been incorporated into the theory of the viscous screw pump for Newtonian fluids. In addition, certain earlier corrections for sidewall and channel curvature effects have been simplified. The result is a single, refined formula for the prediction of the pressure-flow relation for these pumps.

  14. Study on stable equilibrium of levitated impeller in rotary pump with passive magnetic bearings.

    PubMed

    Qian, K X; Wan, F K; Ru, W M; Zeng, P; Yuan, H Y

    2006-01-01

    It is widely acknowledged that the permanent maglev cannot achieve stable equilibrium; the authors have developed, however, a stable permanent maglev centrifugal blood pump. Permanent maglev needs no position detection and feedback control of the rotor, nevertheless the eccentric distance (ED) and vibration amplitude (VA) of the levitator have been measured to demonstrate the levitation and to investigate the factors affecting levitation. Permanent maglev centrifugal impeller pump has a rotor and a stator. The rotor is driven by stator coil and levitated by two passive magnetic bearings. The rotor position is measured by four Hall sensors, which are distributed evenly and peripherally on the end of the stator against the magnetic ring of the bearing on the rotor. The voltage differences of the sensors due to different distances between the sensors and the magnetic ring are converted into ED. The results verify that the rotor can be disaffiliated from the stator if the rotating speed and the flow rate of the pump are large enough, that is, the maximal ED will reduce to about half of the gap between the rotor and the stator. In addition, the gap between rotor and stator and the viscosity of the fluid to be pumped also affect levitation. The former has an optimal value of approximately 2% of the radius of the rotor. For the latter, levitation stability is better with higher viscosity, meaning smaller ED and VA. The pressure to be pumped has no effect on levitation. PMID:16531346

  15. Numerical research on the effects of impeller pump-out vanes on axial force in a solid-liquid screw centrifugal pump

    NASA Astrophysics Data System (ADS)

    Cheng, X. R.; Li, R. N.; Gao, Y.; Guo, W. L.

    2013-12-01

    A commercial CFD code has been used to predict the performance of a screw centrifugal pump with pump-out vanes, especially when changing regularity of impeller axial force based on the solid-liquid two-phase flow. The Unsteady Reynolds Averaged Navier-Stokes (URANS) approach has been applied to solve the unsteady, incompressible, three-dimensional turbulent. The SIMPLEC algorithm, standard wall functions and mix two-phase flow model were applied. The RNG k ?-model was used to account the turbulence effects. By changing the number of impeller pump-out vanes and width, six different screw centrifugal pump numerical simulation projects were given, and each scheme in the different solid volume fraction were calculated respectively. The change rules of axial force, velocity and pressure distribution of flow field were obtained on the different condition and different volume fraction. The results showed that the axial forces values based solid-fluid two-phase greater than based single-phase clear water, but both changing regularity of the axial force were consistent; as same condition, the same solid-phase volume concentration, with the increase of pump-out vanes number or width, the impeller axial force increased as well. Meanwhile the number of the pump-out vanes and the width of pump-out vanes in balancing the impeller axial force, there are the most optimal value.

  16. Simulation and experiment of the effect of clearance of impeller wear-rings on the performance of centrifugal pump

    NASA Astrophysics Data System (ADS)

    Chen, S. X.; Pan, Z. Y.; Wu, Y. L.; Zhang, D. Q.

    2012-11-01

    The effect of clearance of impeller wear-rings on the performance of a centrifugal pump was investigated numerically and experimentally. The whole flow field model including front and back shrouds of pump was designed so as to accurately calculate the head and efficiency of the centrifugal pump. Based on RNG k-? turbulence model, three wear-rings schemes were established, and the effects of clearance of impeller wear-rings on the hydraulic efficiency and mechanical efficiency of the centrifugal pump was analyzed, chiefly from the turbulent kinetic energy, vorticity and radial force angles. According to the results, it can be drawn that the head and total efficiency of the centrifugal pump increase as the clearance value of wear-rings narrows. The following reasons may account for it: firstly, as the clearance value of wear-rings declines, the turbulent kinetic energy and energy dissipation decrease within the impeller, and the impact of secondary flow at the inlet of impeller on the mainstream weakens slowly, which leads to a lower hydraulic loss, thus a higher hydraulic efficiency; secondly, radial force decreases with the clearance value of wear-rings, so the eccentric whirl of centrifugal pump is dampened, which results in a lower mechanical loss and a higher mechanical efficiency; thirdly, the front shroud leakage diminishes with the clearance value of wear-rings, therefore, the volume loss is reduced and volume efficiency improved. Finally, the first wear-ring scheme of impeller is adopted after comprehensive comparison of these three wear-ring schemes, because its efficiency is highest and it satisfies the requirements of the engineering application.

  17. Generating an indicator for pump impeller damage using half and full spectra, fuzzy preference-based rough sets and PCA

    NASA Astrophysics Data System (ADS)

    Zhao, Xiaomin; Zuo, Ming J.; Patel, Tejas H.

    2012-04-01

    Parameters that vary monotonically with damage propagation are useful in condition monitoring. However, it is not easy to find such parameters especially for complex systems like pumps. A method using half and full spectra, fuzzy preference-based rough sets and principal component analysis (PCA) is proposed to generate such an indicator for tracking impeller damage in a centrifugal slurry pump. Half and full spectra are used for extracting features related to pump health status. A fuzzy preference-based rough set model is employed in the process of selecting features reflecting the damage propagation monotonically. PCA is used to condense the features and generate an indicator which represents the damage propagation. The effectiveness of the proposed method is tested using laboratory experimental data. Results show that the indicator generated by the proposed method can clearly and monotonically distinguish the health status of the pump impeller.

  18. Analyzing pumped-well impeller logs to ascertain vertical hydraulic conductivity variations

    NASA Astrophysics Data System (ADS)

    Parker, A. H.; West, J.; Odling, N. E.; Bottrell, S. H.

    2007-12-01

    Horizontal variations in the hydraulic conductivity of aquifers are generally well characterized through simple pump test analyses. However, vertical variations are often poorly understood and misrepresented in the regional models used by regulatory bodies and water companies. Understanding these is key for predicting flow paths and hence the behavior of contaminants in the aquifer that might present a risk to public drinking water supplies. Traditionally, packer tests were used to characterize these variations, but they can be time consuming and costly to perform. However, other techniques have been developed which can quantify these variations, including impeller logging. This study aims to present new, more rigorous methods of analyzing impeller flow log data. Impeller logs were taken under pumped conditions in open wells in a chalk aquifer located in N. England. Theoretically, hydraulic conductivity can be obtained from the gradient in flow rate with depth. However, data are typically noisy due to turbulent flow and hole diameter variations with depth; so directly converting the flow rate gradient to hydraulic conductivity leads to rapid non-physical variation and negative hydraulic conductivity values. Correcting for hole diameter variations using caliper logs proved difficult due to phenomena such as jetting, whereby when the water enters a widening, it does not instantly slow down. In order to obtain more realistic hydraulic conductivity profiles, we firstly tried a data smoothing algorithm, but this approach distorted the data and still gave an unacceptable noise level. Instead, a layered modeling approach has been developed. A hydraulic conductivity profile consisting of a discrete number of uniform layers is constructed, and layer thicknesses and hydraulic conductivities are varied until a satisfactory fit to the observed flow log is achieved. Results from field sites on the confined Chalk aquifer of East Yorkshire in the United Kingdom showed good correlation to packer test analysis. The absence of significant ambient flows at this test site made the final analysis relatively simple. By testing boreholes across the aquifer a pattern of hydraulic conductivity variation with depth can be established, and compared to the proposed geological and climatic reasons for the variations' existence.

  19. Development of a surface micromachined spiral-channel viscous pump

    NASA Astrophysics Data System (ADS)

    Kilani, Mohammad Ibrahim

    This work introduces a new pump, called the spiral pump, which targets the surface micromachining technology. We demonstrate the possibility of realizing the spiral pump geometry in standard surface micromachining, lay out the theoretical foundation for its operation, and conduct an objective assessment for its practicality. The spiral pump is a shear-driven viscous pump, which works by rotating a disk with a spiral groove at a close proximity over a stationary plate. Fluid contained in the spiral groove between the stationary plate and the rotating disk, is subject to a net tangential viscous stress, which allows it to be transported against an imposed pressure difference. A number of spiral pumps were fabricated in 5 levels of polysilicon using Sandia's Ultraplanar Multilevel Surface Micromachining Technology, SUMMiT, and the fabricated micropump were tested in dry-run mode using electrostatic probing and optical microscopy. To achieve a more comprehensive understanding of the spiral micropump operation, an analytical model was developed for the flow field in the spiral channel of the pump using an approximation which replaces the spiral channel with an equivalent straight channel with appropriate dimensions and boundary conditions. An analytical solution for this model at the lubrication limit relates the flow rate, torque and power consumption of the spiral pump to the pressure difference and rotation rate. The model was validated using macroscale experiments conducted on a scaled up spiral pump model, which involved a quantitative characterization of the spiral pump performance. Those experiments validate the developed theory and help assess the practicality of the spiral pump concept. In addition to the spiral pump, two positive-displacement ring-gear pumps were designed and fabricated in this work. The feasibility of surface micromachined ring-gear pumps is briefly investigated in this work, and compare to that of the spiral micropump.

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

    NASA Astrophysics Data System (ADS)

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

    2015-04-01

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

  1. Centrifugal acceleration modes for incompressible fluid in the leakage annulus between a shrouded pump impeller and its housing

    NASA Technical Reports Server (NTRS)

    Childs, D. W.

    1991-01-01

    An algorithm is developed for calculating complex eigenvalues and eigenvectors associated with the fluid resonances and is used to analyze the perturbed flow in the leakage path between a shrouded-pump impeller and its housing. The eigenvalues obtained are consistent with the forced-response curves. First- and second-natural-frequency eigensolutions are presented for mode shapes corresponding to lateral excitations, and first-natural-frequency eigensolutions are presented for mode shapes corresponding to axial excitation.

  2. Unshrouded Centrifugal Turbopump Impeller

    NASA Technical Reports Server (NTRS)

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

    1999-01-01

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

  3. Compressibility effects on rotor forces in the leakage path between a shrouded pump impeller and its housing

    NASA Technical Reports Server (NTRS)

    Cao, Nhai The

    1993-01-01

    A modified approach to Childs' previous work on fluid-structure interaction forces in the leakage path between an impeller shroud and its housing is presented in this paper. Three governing equations consisting of continuity, path-momentum, and circumferential-momentum equations were developed to describe the leakage path inside a pump impeller. Radial displacement perturbations were used to solve for radial and circumferential force coefficients. In addition, impeller-discharge pressure disturbances were used to obtain pressure oscillation responses due to precessing impeller pressure wave pattern. Childs' model was modified from an incompressible model to a compressible barotropic-fluid model (the density of the working fluid is a function of the pressure and a constant temperature only). Results obtained from this model yielded interaction forces for radial and circumferential force coefficients. Radial and circumferential forces define reaction forces within the impeller leakage path. An acoustic model for the same leakage path was also developed. The convective, Coriolis, and centrifugal acceleration terms are removed from the compressible model to obtain the acoustics model. A solution due to impeller discharge pressure disturbances model was also developed for the compressible and acoustics models. The results from these modifications are used to determine what effects additional perturbation terms in the compressible model have on the acoustic model. The results show that the additional fluid mechanics terms in the compressible model cause resonances (peaks) in the force coefficient response curves. However, these peaks only occurred at high values of inlet circumferential velocity ratios greater than 0.7. The peak pressure oscillation was shown to occur at the wearing ring seal. Introduction of impeller discharge disturbances with n = 11 diametral nodes showed that maximum peak pressure oscillations occurred at nondimensional precession frequencies of f = 6.4 and f = 7.8 for this particular pump. Bolleter's results suggest that for peak pressure oscillations to occur at the wearing ring seal, the nondimensional excitation frequency should be on the order of f = 2.182 for n = 11. The resonances found in this research do not match the excitation frequencies predicted by Bolleter. At the predicted peak excitation frequencies given by Bolleter, the compressible model shows an attenuation of the pressure oscillations at the seal exit. The compressibility of the fluid does not have a significant influence on the model at low values of nondimensional excitation frequency. At high values of nondimensional frequency, the effects of compressibility become more significant. For the acoustic analysis, the convective, Coriolis, and centrifugal acceleration terms do affect the results to a limited extent for precession excitation and to a large extent for a pressure excitation when the fluid operates at relatively high Mach numbers.

  4. Numerical investigation of sediment erosion to the impeller in a double-suction centrifugal pump

    NASA Astrophysics Data System (ADS)

    Yang, C. X.; Dong, F. D.; Cheng, X. R.

    2013-12-01

    Based on Euler-Lagrange multiphase flow model and Finnie ductile material erosion model, using phase coupled SIMPLE algorithm, k-e RNG turbulence model and Reynolds Averaged Navier-Stokes (RANS) equation, the solid-liquid two-phase flows in a double-suction centrifugal pump is simulated. The erosion rate and solid mass concentration distribution on the pressure and suction surfaces of blades were obtained in different situations, which include different solid mass concentration (2.17kg/m3, 8.66kg/m3 and 14kg/m3) and different sediment diameter (0.019mm, 0.036mm, and 0.076mm). By comparisons of the test and numerical simulation values, the reliability of numerical calculation method has been verified. The numerical simulation result obtained show that the Finnie ductile material erosion model can accurately predict the erosion rate and erosion areas on the impeller. The erosion rate is increases with solid sediment diameter or solid mass concentration increasing. The main erosion areas on the pressure surface of blades near the blade inlet and outlet and close to the hub, and on the suction surface of blades near the blade inlet and close to the hub. For different sediment diameter or solid mass concentration, the erosion rate on the pressure surface of blades is always greater than that on its suction surface.

  5. Design rules for pumping and metering of highly viscous fluids in microfluidics

    E-print Network

    Kenis, Paul J. A.

    Design rules for pumping and metering of highly viscous fluids in microfluidics Sarah L. Perry.1039/c0lc00035c The use of fluids that are significantly more viscous than water in microfluidics has a theoretical treatment for the flow of highly viscous fluids in deforming microfluidic channels, particularly

  6. The Effects of the Back Clearance Size and the Balance Holes on the Back Clearance Flow of the Centrifugal Pump with Semi-Open Impeller

    E-print Network

    Park, Sang

    2010-01-16

    on the effect of the back clearance on the hydrodynamic forces upon the semi-open impeller showed the opposite trend: increasing the back clearance results in the reduced axial loading. In this work, the CFD simulation of an entire pump and detailed analysis...

  7. Impeller shroud

    Microsoft Academic Search

    1987-01-01

    In a compressor for a gas turbine engine, an engine housing, a rotor assembly including an impeller, the impeller has an inlet portion with an axial component and an outlet portion with a radial component. The impeller includes a hub having a flared cantilever radial configuration and unshrouded blade tips, the rotor assembly being mounted to the engine housing by

  8. Computational fluid dynamics verified the advantages of streamlined impeller design in improving flow patterns and anti-haemolysis properties of centrifugal pump.

    PubMed

    Qian, K X; Wang, F Q; Zeng, P; Ru, W M; Yuan, H Y; Feng, Z G

    2006-01-01

    Computational fluid dynamics (CFD) technology was applied to predict the flow patterns in the authors' streamlined blood pump and an American bio-pump with straight vanes and shroud, respectively. Meanwhile, haemolysis comparative tests of the two pumps were performed to verify the theoretical analysis. The results revealed that the flow patterns in the streamlined impeller are coincident with its logarithmic vanes and parabolic shroud, and there is neither separate flow nor impact in the authors' pump. In the bio-pump, the main flow has the form of logarithmic spiral in vertical section and parabola in cross section, thus there are both stagnation and swirl between the main flow and the straight vanes and shroud. Haemolysis comparative tests demonstrated that the authors' pump has an index of haemolysis of 0.030, less than that of the bio-pump (0.065). PMID:17060163

  9. Redesign of turbine-pump impeller and diffuser using hydrodynamic design techniques. Final report

    SciTech Connect

    Hamrick, J.T.

    1980-04-01

    It is indicated that in 1976 the average operating efficiency of well irrigation pumps in the US, including losses in the column pipe and line shaft, was 55.5%, but information is presented to show that losses in a pumping system can be reduced and that it is possible to reach a goal of 82% system efficiency. Hydrodynamic design methods which are used to analyze and modify a commercially available pump are presented. The results of tests with the pump are presented for which delivery losses were reduced by means of a packer at the pump and for which line shaft losses were reduced by means of a high strength line shaft. Methods of designing pumps that have a broader high efficiency range are explored, and a design approach for doing so is presented. The method was not evaluated experimentally. (MCW)

  10. Performance correction chart of centrifugal oil pump for handling viscous liquids

    NASA Astrophysics Data System (ADS)

    Cao, G. J.; Zhang, W. H.; Chen, J.; Fu, S. H.

    2013-12-01

    The viscosity of oil has a pronounced impact on the operating conditions of the pump. Pumps that are tested with water but are used to transport viscous fluids must have their head, flow, and efficiency values corrected to approximate their performance with the viscous fluid. In this article the hydraulic characteristics of centrifugal oil pumps with different specific speeds for pumping viscous fluids are studied experimentally. The relationship of correction factor with performance characteristics, rotational speed and oil viscosity is investigated. According to the affinity law by KSB, the performance correction chart of flow rate, head and efficiency is plotted. The typical calculated examples show that the calculated results by the diagram methods are consistent with the experiments.

  11. A finite-element-based perturbation model for the rotordynamic analysis of shrouded pump impellers: Part 1: Model development and applications

    NASA Astrophysics Data System (ADS)

    Baskharone, Erian A.

    1993-09-01

    This study concerns the rotor dynamic characteristics of fluid-encompassed rotors, with special emphasis on shrouded pump impellers. The core of the study is a versatile and categorically new finite-element-based perturbation model, which is based on a rigorous flow analysis and what we have generically termed the 'virtually' deformable finite-element approach. The model is first applied to the case of a smooth annular seal for verification purposes. The rotor excitation components, in this sample problem, give rise to a purely cylindrical, purely conical, and a simultaneous cylindrical/conical rotor whirl around the housing centerline. In all cases, the computed results are compared to existing experimental and analytical data involving the same seal geometry and operating conditions. Next, two labyrinth-seal configurations, which share the same tooth-to-tooth chamber geometry but differ in the total number of chambers, were investigated. The results, in this case, are compared to experimental measurements for both seal configurations. The focus is finally shifted to the shrouded-impeller problem, where the stability effects of the leakage flow in the shroud-to-housing secondary passage are investigated. To this end, the computational model is applied to a typical shrouded-impeller pump stage, fabricated and rotor dynamically tested by Sulzer Bros., and the results compared to those of a simplified 'bulk-flow' analysis and Sulzer Bros.' test data. In addition to assessing the computed rotor dynamic coefficients, the shrouded-impeller study also covers a controversial topic, namely that of the leakage-passage inlet swirl, which was previously cited as the origin of highly unconventional (resonance-like) trends of the fluid-exerted forces. In order to validate this claim, a 'microscopic' study of the fluid/shroud interaction mechanism is conducted, with the focus being on the structure of the perturbed flow field associated with the impeller whirl. The conclusions of this study were solidified by the outcome of a numerical-certainty exercise, where the grid dependency of the numerical results is objectively examined. The final phase of the shrouded-impeller investigation involves the validation of a built-in assumption, in all other perturbation models, whereby single-harmonic tangential distributions of all the flow thermophysical properties are imposed. The last phase of the investigation course is aimed at verifying the fine details of the perturbed flow field in light of recent set of detailed LDA measurements in a smooth annular seal. Grid dependency of the fluid-induced forces is also investigated, and specific recommendations are made.

  12. A finite-element-based perturbation model for the rotordynamic analysis of shrouded pump impellers: Part 1: Model development and applications

    NASA Technical Reports Server (NTRS)

    Baskharone, Erian A.

    1993-01-01

    This study concerns the rotor dynamic characteristics of fluid-encompassed rotors, with special emphasis on shrouded pump impellers. The core of the study is a versatile and categorically new finite-element-based perturbation model, which is based on a rigorous flow analysis and what we have generically termed the 'virtually' deformable finite-element approach. The model is first applied to the case of a smooth annular seal for verification purposes. The rotor excitation components, in this sample problem, give rise to a purely cylindrical, purely conical, and a simultaneous cylindrical/conical rotor whirl around the housing centerline. In all cases, the computed results are compared to existing experimental and analytical data involving the same seal geometry and operating conditions. Next, two labyrinth-seal configurations, which share the same tooth-to-tooth chamber geometry but differ in the total number of chambers, were investigated. The results, in this case, are compared to experimental measurements for both seal configurations. The focus is finally shifted to the shrouded-impeller problem, where the stability effects of the leakage flow in the shroud-to-housing secondary passage are investigated. To this end, the computational model is applied to a typical shrouded-impeller pump stage, fabricated and rotor dynamically tested by Sulzer Bros., and the results compared to those of a simplified 'bulk-flow' analysis and Sulzer Bros.' test data. In addition to assessing the computed rotor dynamic coefficients, the shrouded-impeller study also covers a controversial topic, namely that of the leakage-passage inlet swirl, which was previously cited as the origin of highly unconventional (resonance-like) trends of the fluid-exerted forces. In order to validate this claim, a 'microscopic' study of the fluid/shroud interaction mechanism is conducted, with the focus being on the structure of the perturbed flow field associated with the impeller whirl. The conclusions of this study were solidified by the outcome of a numerical-certainty exercise, where the grid dependency of the numerical results is objectively examined. The final phase of the shrouded-impeller investigation involves the validation of a built-in assumption, in all other perturbation models, whereby single-harmonic tangential distributions of all the flow thermophysical properties are imposed. The last phase of the investigation course is aimed at verifying the fine details of the perturbed flow field in light of recent set of detailed LDA measurements in a smooth annular seal. Grid dependency of the fluid-induced forces is also investigated, and specific recommendations are made.

  13. Flow of viscous oil in the volute of a centrifugal pump

    NASA Astrophysics Data System (ADS)

    Li, Wen-Guang

    2002-02-01

    The flows of water as well as viscous oil in the three rectangular sections of the volute of a centrifugal pump are measured by using a two-dimensional laser Doppler velocimetry(LDV) in the best efficiency and part-loading points, respectively. The results show that the magnitude of tangential component of absolute velocity is one order larger than that of radial component. There are spiral motions in the sections of the volute. The angular momentum of liquid in the volute isn’t conservative and the viscosity of liquid is larger, this situation is more severe. The flow of water or viscous oil in the volute is diffused in both best efficiency point and part-loading points. The diffusion of the flow is weakened while pumping the viscous oil.

  14. Incompressible viscous flow computations for the pump components and the artificial heart

    NASA Technical Reports Server (NTRS)

    Kiris, Cetin

    1992-01-01

    A finite-difference, three-dimensional incompressible Navier-Stokes formulation to calculate the flow through turbopump components is utilized. The solution method is based on the pseudocompressibility approach and uses an implicit-upwind differencing scheme together with the Gauss-Seidel line relaxation method. Both steady and unsteady flow calculations can be performed using the current algorithm. In this work, the equations are solved in steadily rotating reference frames by using the steady-state formulation in order to simulate the flow through a turbopump inducer. Eddy viscosity is computed by using an algebraic mixing-length turbulence model. Numerical results are compared with experimental measurements and a good agreement is found between the two. Included in the appendix is a paper on incompressible viscous flow through artificial heart devices with moving boundaries. Time-accurate calculations, such as impeller and diffusor interaction, will be reported in future work.

  15. Pressure and momentum field investigation of a centrifugal pump through dynamic loading of a semi-open impeller

    E-print Network

    Anwer, Sohaib

    1998-01-01

    A study was performed to investigate the variation in the forces and moments acting on the front and back sides of a semi-open impeller. Three rotational speeds and five volumetric flow rates for each speed were identified as the operating...

  16. Pressure and momentum field investigation of a centrifugal pump through dynamic loading of a semi-open impeller 

    E-print Network

    Anwer, Sohaib

    1998-01-01

    A study was performed to investigate the variation in the forces and moments acting on the front and back sides of a semi-open impeller. Three rotational speeds and five volumetric flow rates for each speed were identified as the operating...

  17. Development of turbo-viscous pump with ceramic rotor assembly and oil-free driving unit

    SciTech Connect

    Murakami, Y.; Abe, T. (Japan Atomic Energy Research Institute (JAERI), Naka Fusion Research Establishment, Naka-machi, Naka-gun, Ibaraki-ken, Japan (JP)); Ohsawa, H.; Hata, S. (Mitsubishi Heavy Industries, Ltd., 4-6-22, Kan-on-shinmachi, Hiroshima, Japan (JP))

    1991-05-01

    In order to establish a dynamic pumping system for fusion reactors and other advanced vacuum devices, a new type of roughing pump named turbo-viscous pump has been developed. The construction of the pump features a multistage ceramic (silicon nitride) rotor assembly and an oil-free driving unit. The rotor assembly has parallel rotor disks, between which project stator disks from the outer casing with rotor-stator clearances {lt}100 {mu}m, and a shaft with gas turbine blades. Spiral grooves are cut on either side of the rotor or stator disk of each stage, each of them starting near the center (or at the periphery) and ending at the periphery (or near the center). The pump shaft is supported by gas bearings and is driven by gas impulse turbines at {similar to}25 000 rpm. No lubricating or cooling oil is used. The turbo-viscous pump works in a wide pressure range from atmospheric pressure to 10{sup {minus}3} Pa. The pumping speed and ultimate pressure attained so far are 0.28 m{sup 3}/min (at inlet pressures between 10{sup {minus}1} and 10{sup 2} Pa) and 1{times}10{sup {minus}3} Pa, respectively.

  18. Compressibility effects on rotor forces in the leakage path between a shrouded pump impeller and its housing

    E-print Network

    Cao, Nhai The

    1993-01-01

    Axial and circumferential directions Zeroth and first-order perturbations CHAPTER I INTRODUCTION In the past, wear-ring seals used on the SSME HPFTP (Space Shuttle Main Engine High Pressure Fuel Turbopump) made from KEIR plastic came back after...-flow model will be developed and used to simulate the leakage path inside the first impeller stage of the Space Shuttle Main Engine Turbopump. Results from the computation should indicate if any interaction exists between acoustic and centrifugal...

  19. On-site Real-Time Inspection System for Pump-impeller using X-band Linac X-ray Source

    SciTech Connect

    Yamamoto, Tomohiko; Natsui, Takuya; Taguchi, Hiroki; Taniguchi, Yoshihiro; Lee, Ki woo; Hashimoto, Eiko; Sakamoto, Fumito; Sakumi, Akira; Yusa, Noritaka; Uesaka, Mitsuru [Nuclear Professional School, the University of Tokyo, 2-22 Shirakata-Shirane, Tokai, Naka, Ibaraki (Japan); Nakamura, Naoki; Yamamoto, Masashi; Tanabe, Eiji [Accuthera Inc. 2-7-6 Kurigi, Asao, Kawasaki, Kanagawa 215-0033 Japan (Japan)

    2009-03-10

    The methods of nondestructive testing (NDT) are generally ultrasonic, neutron, eddy-current and X-rays, NDT by using X-rays, in particular, is the most useful inspection technique having high resolution. We can especially evaluate corroded pipes of petrochemical complex, nuclear and thermal-power plants by the high energy X-ray NDT system. We develop a portable X-ray NDT system with X-band linac and magnetron. This system can generate a 950 keV electron beam. We are able to get X-ray images of samples with 1 mm spatial resolution. This system has application to real time impeller inspection because linac based X-ray sources are able to generate pulsed X-rays. So, we can inspect the rotating impeller if the X-ray pulse rate is synchronized with the impeller rotation rate. This system has application in condition based maintenance (CBM) of nuclear plants, for example. However, 950 keV X-ray source can only be used for thin tubes with 20 mm thickness. We have started design of a 3.95 MeV X-band linac for broader X-ray NDT application. We think that this X-ray NDT system will be useful for corrosion wastage and cracking in thicker tubes at nuclear plants and impeller of larger pumps. This system consists of X-band linac, thermionic cathode electron gun, magnetron and waveguide components. For achieving higher electric fields the 3.95 MeV X-band linac structure has the side-coupled acceleration structure. This structure has more efficient acceleration than the 950 keV linac with alternating periodic structure (APS). We adopt a 1.3 MW magnetron for the RF source. This accelerator system is about 30 cm long. The beam current is about 150 mA, and X-ray dose rate is 10 Gy at 1 m/500 pps. In this paper, the detail of the whole system concept and the electromagnetic field of designed linac structure will be reported.

  20. On-site Real-Time Inspection System for Pump-impeller using X-band Linac X-ray Source

    NASA Astrophysics Data System (ADS)

    Yamamoto, Tomohiko; Natsui, Takuya; Taguchi, Hiroki; Taniguchi, Yoshihiro; Lee, Ki woo; Hashimoto, Eiko; Sakamoto, Fumito; Sakumi, Akira; Yusa, Noritaka; Uesaka, Mitsuru; Nakamura, Naoki; Yamamoto, Masashi; Tanabe, Eiji

    2009-03-01

    The methods of nondestructive testing (NDT) are generally ultrasonic, neutron, eddy-current and X-rays, NDT by using X-rays, in particular, is the most useful inspection technique having high resolution. We can especially evaluate corroded pipes of petrochemical complex, nuclear and thermal-power plants by the high energy X-ray NDT system. We develop a portable X-ray NDT system with X-band linac and magnetron. This system can generate a 950 keV electron beam. We are able to get X-ray images of samples with 1 mm spatial resolution. This system has application to real time impeller inspection because linac based X-ray sources are able to generate pulsed X-rays. So, we can inspect the rotating impeller if the X-ray pulse rate is synchronized with the impeller rotation rate. This system has application in condition based maintenance (CBM) of nuclear plants, for example. However, 950 keV X-ray source can only be used for thin tubes with 20 mm thickness. We have started design of a 3.95 MeV X-band linac for broader X-ray NDT application. We think that this X-ray NDT system will be useful for corrosion wastage and cracking in thicker tubes at nuclear plants and impeller of larger pumps. This system consists of X-band linac, thermionic cathode electron gun, magnetron and waveguide components. For achieving higher electric fields the 3.95 MeV X-band linac structure has the side-coupled acceleration structure. This structure has more efficient acceleration than the 950 keV linac with alternating periodic structure (APS). We adopt a 1.3 MW magnetron for the RF source. This accelerator system is about 30 cm long. The beam current is about 150 mA, and X-ray dose rate is 10 Gy@1 m/500 pps. In this paper, the detail of the whole system concept and the electromagnetic field of designed linac structure will be reported.

  1. Fluid Dynamics of Small, Rugged Vacuum Pumps of Viscous-Drag Type

    NASA Technical Reports Server (NTRS)

    Russell, John M.

    2002-01-01

    The need to identify spikes in the concentration of hazardous gases during countdowns to space shuttle launches has led Kennedy Space Center to acquire considerable expertise in the design, construction, and operation of special-purpose gas analyzers of mass-spectrometer type. If such devices could be miniaturized so as to fit in a small airborne package or backpack them their potential applications would include integrated vehicle health monitoring in later-generation space shuttles and in hazardous material detection in airports, to name two examples. The bulkiest components of such devices are vacuum pumps, particularly those that function in the low vacuum range. Now some pumps that operate in the high vacuum range (e.g. molecular-drag and turbomolecular pumps) are already small and rugged. The present work aims to determine whether, on physical grounds, one may or may not adopt the molecular-drag principle to the low-vacuum range (in which case viscous-drag principle is the appropriate term). The deliverable of the present effort is the derivation and justification of some key formulas and calculation methods for the preliminary design of a single-spool, spiral-channel viscous-drag pump.

  2. Computation of the flow field in a centrifugal impeller with splitter blades

    NASA Technical Reports Server (NTRS)

    Dejong, Frederik J.; Choi, Sang-Keun; Govindan, T. R.; Sabnis, Jayant S.

    1992-01-01

    To support the design effort of the Space Transportation Main Engine (STME) Fuel Pump Stage, viscous flow calculations were performed in a centrifugal impeller with splitter blades. These calculations were carried out with a Navier-Stokes solver (MINT), which employs a linearized block-implicit Alternating Direction Implicit (ADI) procedure to iteratively solve a finite difference form of the system of conservation equations of mass, momentum, and energy in body-fitted coordinates. A computational grid was generated algebraically for the 'channel' between two main blades of the impeller and extended both upstream of the impeller inlet and downstream of the impeller exit so that the appropriate boundary conditions could be applied. The results of the calculations show that although the overall level of flow distortion near the impeller exit is not very large, there is a noticeable difference between the flow patterns in the two 'passages' (one passage between the pressure side of the splitter blade and the suction side of the next full blade).

  3. PIV measurements of flow in an aerated tank stirred by a down- and an up-pumping axial flow impeller

    Microsoft Academic Search

    J. AUBIN; N Le Sauze; J Bertrand; D. F Fletcher; C Xuereb

    2004-01-01

    Liquid phase hydrodynamics in an aerated tank stirred by a down- and an up-pumping pitched blade turbine have been investigated using particle image velocimetry. The effect of agitator configuration and the gas phase on the mean velocity fields and turbulent quantities in the vessel have been investigated. The global mean gas holdup has also been evaluated for the two pumping

  4. Production optimization of sucker rod pumping wells producing viscous oil in Boscan field, Venezuela

    SciTech Connect

    Guirados, C.; Sandoval, J.; Rivas, O.; Troconis, H.

    1995-12-31

    Boscan field is located in the western coast of Maracaibo lake and is operated by Maraven S.A., affiliate of Petroleos de Venezuela S.A. It has 315 active wells, 252 of which are produced with sucker rod pumping. Other artificial lift methods currently applied in this field are hydraulic (piston) pumping (39 wells) and ESP (24 wells). This paper presents the results of the production optimization of two sucker rod pumping wells of Boscan field producing viscous oil. This optimization has been possible due to the development of a new production scheme and the application of system analysis in completion design. The new production scheme involves the utilization of a subsurface stuffing box assembly and a slotted housing, both designed and patented by Intevep S.A., affiliate of Petroleos de Venezuela S.A. The completion design method and software used in the optimization study were also developed by Intevep S.A. The new production scheme and design method proved to be effective in preventing the causes of the above mentioned problems, allowing the increase of oil production under better operating conditions.

  5. Assessment of Cavitation-Erosion Resistance of Potential Pump Impeller Materials for Mercury Service at the Spallation Neutron Source

    SciTech Connect

    Pawel, Steven J [ORNL

    2007-03-01

    Using a standard vibratory horn apparatus, the relative cavitation-erosion resistance of a number of cast alloys in mercury was evaluated to facilitate material selection decisions for Hg pumps. The performance of nine different alloys - in the as-cast condition as well as following a case-hardening treatment intended to increase surface hardness - was compared in terms of weight loss and surface profile development as a function of sonication time in Hg at ambient temperature. The results indicated that among several potentially suitable alloys, CD3MWCuN perhaps exhibited the best overall resistance to cavitation in both the as-cast and surface treated conditions while the cast irons examined were found unsuitable for service of this type. However, other factors, including cost, availability, and vendor schedules may influence a material selection among the suitable alloys for Hg pumps.

  6. Creating A Data Base For Design Of An Impeller

    NASA Technical Reports Server (NTRS)

    Prueger, George H.; Chen, Wei-Chung

    1993-01-01

    Report describes use of Taguchi method of parametric design to create data base facilitating optimization of design of impeller in centrifugal pump. Data base enables systematic design analysis covering all significant design parameters. Reduces time and cost of parametric optimization of design: for particular impeller considered, one can cover 4,374 designs by computational simulations of performance for only 18 cases.

  7. Floating portable pump

    Microsoft Academic Search

    Eberhardt

    1985-01-01

    A floating portable pump is constructed of a float defining a well for containing water, a centrifugal pump supported on the float with its impeller shaft extending vertically and with its suction inlet submerged in water in the well, and an internal combustion engine arranged to drive the pump impeller. The pump and engine are secured together on the float

  8. Aerodynamic Synthesis of a Centrifugal Impeller Using CFD and Measurements

    NASA Technical Reports Server (NTRS)

    Larosiliere, L. M.; Skoch, G. J.; Prahst, P. S.

    1997-01-01

    The performance and flow structure in an unshrouded impeller of approximately 4:1 pressure ratio is synthesized on the basis of a detailed analysis of 3D viscous CFD results and aerodynamic measurements. A good data match was obtained between CFD and measurements using laser anemometry and pneumatic probes. This solidified the role of the CFD model as a reliable representation of the impeller internal flow structure and integrated performance. Results are presented showing the loss production and secondary flow structure in the impeller. The results indicate that while the overall impeller efficiency is high, the impeller shroud static pressure recovery potential is underdeveloped leading to a performance degradation in the downstream diffusing element. Thus, a case is made for a follow-on impeller parametric design study to improve the flow quality. A strategy for aerodynamic performance enhancement is outlined and an estimate of the gain in overall impeller efficiency that might be realized through improvements to the relative diffusion process is provided.

  9. Impeller flow field measurement and analysis

    NASA Technical Reports Server (NTRS)

    Fagan, J. R.; Fleeter, S.

    1991-01-01

    A series of experiments are performed to investigate and quantify the three-dimensional mean flow field in centrifugal compressor flow passages and to evaluate contemporary internal flow models. The experiments include the acquisition and analysis of LDV data in the impeller passages of a low-speed moderate-scale research mixed-flow centrifugal compressor operating at its design point. Predictions from a viscous internal flow model are then correlated with these data. The LDV data show the traditional jet-wake structure observed in many centrifugal compressors, with the wake observed along the shroud 70 percent of the length from the pressure to suction surface. The viscous model predicts the major flow phenomena. However, the correlations of the viscous predictions with the LDV data were poor.

  10. Transient internal characteristic study of a centrifugal pump during startup process

    NASA Astrophysics Data System (ADS)

    Hu, F. F.; Ma, X. D.; Wu, D. Z.; Wang, L. Q.

    2012-11-01

    The transient process of a centrifugal pump existed in a variety of occasions. There were a lot of researches in the external characteristic in startup process and stopping process, but internal characteristics were less observed and studied. Study of the internal flow field had significant meanings. The performance of a pump could be evaluated and improved by revealing the flow field. In the other hand, the prediction of external characteristic was based on the correct analysis of the internal flow. In this paper, theoretical method and numerical simulation were used to study the internal characteristic of a centrifugal pump. The theoretical study showed that the relative flow in an impeller was composed of homogeneous flow and axial vortex flow. The vortex intensity was mainly determined by angular velocity of impeller, flow channel width and blade curvature. In order to get the internal flow field and observe the evolution of transient internal flow in the impeller, Computational Fluid Dynamics(CFD) were used to study the three-dimensional unsteady incompressible viscous flows in a centrifugal pump during starting period. The Dynamic Mesh (DM) method with non-conformal grid boundaries was applied to get the external characteristic and internal flow field. The simulate model included three pumps with different blade numbers and the same blade curvature. The relative velocity vector showed that there was a big axial vortex in impeller channel. At the beginning, the vortex was raised in the pressure side of the impeller outlet and with time went on, it shifted to the middle flow channel of the impeller and the vortex intensity increased. When the speed and flow rate reached a definite value, the influence of the axial vortex began to get smaller. The vortex developed faster when the flow channel got narrower. Due to the evolution of axial vortex, the slip factor during starting period was smaller than that in quasi-steady condition. As a result, transient head was lower than quasi-steady head in startup process.

  11. PIV measurement of internal flow characteristics of very low specific speed semi-open impeller

    NASA Astrophysics Data System (ADS)

    Choi, Y.-D.; Nishino, K.; Kurokawa, J.; Matsui, J.

    2004-11-01

    Detailed particle-image velocimetry (PIV) measurements of flow fields inside semi-open impellers have been performed to understand better the internal flow patterns that are responsible for the unique performance of these centrifugal pumps operated in the range of very low specific speed. Two impellers, one equipped with six radial blades (impeller A) and the other with four conventional backward-swept blades (impeller B), are tested in a centrifugal pump designed to be operated at a non-dimensional specific speed of ns=0.24. Complex flow patterns captured by PIV are discussed in conjunction with the overall pump performance measured separately. It is revealed that impeller A achieves higher effective head than impeller B even though the flow patterns in impeller A are more complex, exhibiting secondary flows and reverse flows in the impeller passage. It is shown that both the localized strong outward flow at the pressure side of each blade outlet and the strong outward through-flow along the suction side of each blade are responsible for the better head performance of impeller A.

  12. Numerical Calculation for Whirling Motion of a Centrifugal Blood Pump with Conical Spiral Groove Bearings

    NASA Astrophysics Data System (ADS)

    Shigemaru, Daichi; Tsukamoto, Hiroshi

    2010-06-01

    Whirling motion of a pump impeller was calculated for the centrifugal blood pump with Conical Spiral Groove Bearings to get a criterion for the instability of impeller whirling motion. The motion of the centrifugal blood pump impeller was calculated based on a spring damping model, and unsteady flow in the pump was computed using the commercial CFD package ANSYS CFX. Also the whirling motion of rotating impeller was measured using two displacement sensors fixed to the blood pump casing. The numerical calculations were done for the blood pump impeller with conical spiral groove bearings, and impeller whirling motion was evaluated.

  13. Axial Pump

    NASA Technical Reports Server (NTRS)

    Bozeman, Richard J., Jr. (Inventor); Akkerman, James W. (Inventor); Aber, Gregory S. (Inventor); VanDamm, George Arthur (Inventor); Bacak, James W. (Inventor); Svejkovsky, Paul A. (Inventor); Benkowski, Robert J. (Inventor)

    1997-01-01

    A rotary blood pump includes a pump housing for receiving a flow straightener, a rotor mounted on rotor bearings and having an inducer portion and an impeller portion, and a diffuser. The entrance angle, outlet angle, axial and radial clearances of blades associated with the flow straightener, inducer portion, impeller portion and diffuser are optimized to minimize hemolysis while maintaining pump efficiency. The rotor bearing includes a bearing chamber that is filled with cross-linked blood or other bio-compatible material. A back emf integrated circuit regulates rotor operation and a microcomputer may be used to control one or more back emf integrated circuits. A plurality of magnets are disposed in each of a plurality of impeller blades with a small air gap. A stator may be axially adjusted on the pump housing to absorb bearing load and maximize pump efficiency.

  14. Effect of impeller design on the flow pattern and mixing in stirred tanks

    Microsoft Academic Search

    T. Kumaresan; Jyeshtharaj B. Joshi

    2006-01-01

    The flow pattern and power number in a vessel depend on the impeller blade angle, number of blades, blade width, blade twist, blade thickness, pumping direction and interaction of flow with the vessel wall. Measurements of the power consumption and flow pattern have been carried out in a stirred vessel of 0.5m diameter for the range of impellers to study

  15. Swimming and pumping by helical waves in viscous and viscoelastic fluids

    NASA Astrophysics Data System (ADS)

    Li, Lei; Spagnolie, Saverio E.

    2015-02-01

    We study helical bodies of arbitrary cross-sectional profile as they swim or transport fluid by the passage of helical waves. Many cases are explored: the external flow problem of swimming in a cylindrical tube or an infinite domain, the internal fluid pumping problem, and confined/unconfined swimming and internal pumping in a viscoelastic (Oldroyd-B) fluid. A helical coordinate system allows for the analytical calculation of swimming and pumping speeds and fluid velocities in the asymptotic regime of nearly cylindrical bodies. In a Newtonian flow, a matched asymptotic analysis results in corrections to the swimming speed accurate to fourth-order in the small wave amplitude, and the results compare favorably with full numerical simulations. We find that the torque-balancing rigid body rotation generally opposes the direction of wave passage, but not always. Confinement can result in local maxima and minima of the swimming speed in the helical pitch, and the effects of confinement decrease exponentially fast with the diameter of the tube. In a viscoelastic fluid, we find that the effects of fluid elasticity on swimming and internal pumping modify the Newtonian results through the mode-dependent complex viscosity, even in a confined domain.

  16. Viscous to inertial pumping transitions in a robotic gill plate array

    NASA Astrophysics Data System (ADS)

    Larson, Mary; Kiger, Ken

    2010-11-01

    Biological oscillating appendage systems are known to exhibit distinct patterns of movement based on their Reynolds number. Flapping kinematics (net flow perpendicular to appendage stroke plane) are associated with Re > 100, while rowing kinematics (flow in the direction of appendage motion) are typically associated with Re < 1. Previous studies of pumping by mayfly nymph gill plate arrays have shown a transition between rowing and flapping at a Re 5. Although the flow generated by the animal could be documented, the limited range of behavior of the animal prevented a detailed study of why and how such a pumping mechanism might be optimized. Towards this end, a two-degree-of-freedom robotic oscillating plate array has been constructed, which allows for the variation of the Reynolds number, plate spacing, plate shape, and stroke/pitch amplitude beyond what is exhibited by the animal system. Using PIV, these combinations allow the individual influence of each feature on the pumping efficiency to be observed, and elucidate how it may be optimized for engineered devices. The current results will compare this simplified system to the flow generated by the typical mayfly, to determine how effectively the model performs in comparison to the more complex animal system.

  17. Water testing of the inducer pump. [LMFBR

    Microsoft Academic Search

    C. Dunn; R. K. Hoshide

    1977-01-01

    The inducer pump, designed and fabricated as a test article to evaluate the inducer\\/impeller pump concept for providing improved suction performance of large sodium pumps, met or exceeded all performance goals. The inducer stage in front of the centrifugal impeller dramatically reduces the size of pumps. It was demonstrated that the inducer can operate at suction specific speeds in excess

  18. Rotary blood pump

    NASA Technical Reports Server (NTRS)

    Benkowski, Robert J. (Inventor); Kiris, Cetin (Inventor); Kwak, Dochan (Inventor); Rosenbaum, Bernard J. (Inventor); Bacak, James W. (Inventor); DeBakey, Michael E. (Inventor)

    1999-01-01

    A blood pump that comprises a pump housing having a blood flow path therethrough, a blood inlet, and a blood outlet; a stator mounted to the pump housing, the stator having a stator field winding for producing a stator magnetic field; a flow straightener located within the pump housing, and comprising a flow straightener hub and at least one flow straightener blade attached to the flow straightener hub; a rotor mounted within the pump housing for rotation in response to the stator magnetic field, the rotor comprising an inducer and an impeller; the inducer being located downstream of the flow straightener, and comprising an inducer hub and at least one inducer blade attached to the inducer hub; the impeller being located downstream of the inducer, and comprising an impeller hub and at least one impeller blade attached to the impeller hub; and preferably also comprising a diffuser downstream of the impeller, the diffuser comprising a diffuser hub and at least one diffuser blade. Blood flow stagnation and clot formation within the pump are minimized by, among other things, providing the inducer hub with a diameter greater than the diameter of the flow straightener hub; by optimizing the axial spacing between the flow straightener hub and the inducer hub, and between the impeller hub and the diffuser hub; by optimizing the inlet angle of the diffuser blades; and by providing fillets or curved transitions between the upstream end of the inducer hub and the shaft mounted therein, and between the impeller hub and the shaft mounted therein.

  19. CFD parametric study of consortium impeller

    NASA Astrophysics Data System (ADS)

    Cheng, Gary C.; Chen, Y. S.; Garcia, Roberto; Williams, Robert W.

    1993-07-01

    Current design of high performance turbopumps for rocket engines requires effective and robust analytical tools to provide design impact in a productive manner. The main goal of this study is to develop a robust and effective computational fluid dynamics (CFD) pump model for general turbopump design and analysis applications. A Finite Difference Navier-Stokes flow solver, FDNS, which includes the extended k-epsilon turbulence model and appropriate moving interface boundary conditions, was developed to analyze turbulent flows in turbomachinery devices. A second-order central difference scheme plus adaptive dissipation terms was employed in the FDNS code, along with a predictor plus multi-corrector pressure-based solution procedure. The multi-zone, multi-block capability allows the FDNS code to efficiently solve flow fields with complicated geometry. The FDNS code has been benchmarked by analyzing the pump consortium inducer, and it provided satisfactory results. In the present study, a CFD parametric study of the pump consortium impeller was conducted using the FDNS code. The pump consortium impeller, with partial blades, is a new design concept of the advanced rocket engines. The parametric study was to analyze the baseline design of the consortium impeller and its modification which utilizes TANDEM blades. In the present study, the TANDEM blade configuration of the consortium impeller considers cut full blades for about one quarter chord length from the leading edge and clocks the leading edge portion with an angle of 7.5 or 22.5 degrees. The purpose of the present study is to investigate the effect and trend of the TANDEM blade modification and provide the result as a design guideline. A 3-D flow analysis, with a 103 x 23 x 30 mesh grid system and with the inlet flow conditions measured by Rocketdyne, was performed for the baseline consortium impeller. The numerical result shows that the mass flow rate splits through various blade passages are relatively uniform. Due to the complexity of blade geometries, the TANDEM blade configurations were analyzed with the multi-zone grid structure. Both the 7.5 deg- and the 22.5 deg-clocking TANDEM blade cases utilized a 80K mesh system. The numerical result of two TANDEM blade modifications indicates the efficiency and the head are worse than those of the baseline case due to larger flow distortion. The gap between the TANDEM blade and the full blade allows the flow passes through and heavily loads the pressure side of the partial blade such that flow reversal occurs near the suction side of the splitter. The flow split at the exit of impeller blades is very non-uniform for TANDEM blade cases, and this will greatly induce the side load on the diffuser. impeller.

  20. CFD analyses for advanced pump design

    NASA Astrophysics Data System (ADS)

    Dejong, F. J.; Choi, S.-K.; Govindan, T. R.

    1994-04-01

    As one of the activities of the NASA/MSFC Pump Stage Technology Team, the present effort was focused on using CFD in the design and analysis of high performance rocket engine pumps. Under this effort, a three-dimensional Navier-Stokes code was used for various inducer and impeller flow field calculations. An existing algebraic grid generation procedure was-extended to allow for nonzero blade thickness, splitter blades, and hub/shroud cavities upstream or downstream of the (main) blades. This resulted in a fast, robust inducer/impeller geometry/grid generation package. Problems associated with running a compressible flow code to simulate an incompressible flow were resolved; related aspects of the numerical algorithm (viz., the matrix preconditioning, the artificial dissipation, and the treatment of low Mach number flows) were addressed. As shown by the calculations performed under the present effort, the resulting code, in conjunction with the grid generation package, is an effective tool for the rapid solution of three-dimensional viscous inducer and impeller flows.

  1. Numerical Simulation of Tubular Pumping Systems with Different Regulation Methods

    Microsoft Academic Search

    Honggeng Zhu; Rentian Zhang; Dongsheng Deng; Xusong Feng; Linbi Yao

    2010-01-01

    Since the flow in tubular pumping systems is basically along axial direction and passes symmetrically through the impeller, most satisfying the basic hypotheses in the design of impeller and having higher pumping system efficiency in comparison with vertical pumping system, they are being widely applied to low-head pumping engineering. In a pumping station, the fluctuation of water levels in the

  2. Design and Test of Mixed-flow Impellers III : Design and Experimental Results for Impeller Model MFI-2A and Comparison with Impeller Model MFI-1A

    NASA Technical Reports Server (NTRS)

    Hamrick, Joseph T; Osborn, Walter M; Beede, William L

    1953-01-01

    A mixed-flow impeller was designed to give a prescribed blade-surface velocity distribution at mean blade height for a given hub-shroud profile. The blade shape at mean blade height, which was produced by the prescribed velocity distribution, was extended by means of radial lines to form the composite blade shape from hub to shroud. The resulting blade was relatively thick; therefore, it was necessary to retain the inverse blade taper which resulted from extension of the radial lines in order to prevent merging or near merging of the separate blades near the hub. For the first test version of the impeller, designated the MFI-2A, the blade height was arbitrarily made greater than that for the basic impeller (the MFI-2) to allow for viscous effects. At design equivalent speed of 1400 feet per second the peak pressure ratio and maximum adiabatic efficiency were 3.95 and 79 percent, respectively. The adiabatic efficiency of the MFI-2A is four points lower than that for impeller model MFI-1A, but because of the higher slip factor for the MFI-2A, the pressure ratios are approximately equal. The procedures followed in the design of the MFI-1A and MFI-2A were, in general, the same; and, although the prescribed initial condition resulted in geometrical configurations that were quite dissimilar, the resulting performance characteristics compare favorably with designs for which considerable development work has been necessary.

  3. Osmotic Stress and Viscous Retardation of the Na,K-ATPase Ion Pump

    PubMed Central

    Esmann, Mikael; Fedosova, Natalya U.; Marsh, Derek

    2008-01-01

    The transport function of the Na pump (Na,K-ATPase) in cellular ion homeostasis involves both nucleotide binding reactions in the cytoplasm and alternating aqueous exposure of inward- and outward-facing ion binding sites. An osmotically active, nonpenetrating polymer (poly(ethyleneglycol); PEG) and a modifier of the aqueous viscosity (glycerol) were used to probe the overall and partial enzymatic reactions of membranous Na,K-ATPase from shark salt glands. Both inhibit the steady-state Na,K-ATPase as well as Na-ATPase activity, whereas the K+-dependent phosphatase activity is little affected by up to 50% of either. Both Na,K-ATPase and Na-ATPase activities are inversely proportional to the viscosity of glycerol solutions in which the membranes are suspended, in accordance with Kramers' theory for strong coupling of fluctuations at the active site to solvent mobility in the aqueous environment. PEG decreases the affinity for Tl+ (a congener for K+), whereas glycerol increases that for the nucleotides ATP and ADP in the presence of NaCl but has little effect on the affinity for Tl+. From the dependence on osmotic stress induced by PEG, the aqueous activation volume for the Na,K-ATPase reaction is estimated to be ?5–6 nm3 (i.e., ?180 water molecules), approximately half this for Na-ATPase, and essentially zero for p-nitrophenol phosphatase. The change in aqueous hydrated volume associated with the binding of Tl+ is in the region of 9 nm3. Analysis of 15 crystal structures of the homologous Ca-ATPase reveals an increase in PEG-inaccessible water space of ?22 nm3 between the E1-nucleotide bound forms and the E2-thapsigargin forms, showing that the experimental activation volumes for Na,K-ATPase are of a magnitude comparable to the overall change in hydration between the major E1 and E2 conformations of the Ca-ATPase. PMID:18055532

  4. Apparatus for pumping liquids at or below the boiling point

    DOEpatents

    Bingham, Dennis N. (Idaho Falls, ID)

    2002-01-01

    A pump comprises a housing having an inlet and an outlet. An impeller assembly mounted for rotation within the housing includes a first impeller piece having a first mating surface thereon and a second impeller piece having a second mating surface therein. The second mating surface of the second impeller piece includes at least one groove therein so that at least one flow channel is defined between the groove and the first mating surface of the first impeller piece. A drive system operatively associated with the impeller assembly rotates the impeller assembly within the housing.

  5. Slip due to surface roughness for a Newtonian liquid in a viscous microscale disk pump

    NASA Astrophysics Data System (ADS)

    Ligrani, Phil; Blanchard, Danny; Gale, Bruce

    2010-05-01

    In the present study, hydrophobic roughness is used to induce near-wall slip in a single rotating-disk micropump operating with Newtonian water. The amount of induced slip is altered by employing different sizes of surface roughness on the rotating disk. The magnitudes of slip length and slip velocities increase as the average size of the surface roughness becomes larger. In the present study, increased slip magnitudes from roughness are then associated with reduced pressure rise through the pump and lower radial-line-averaged shear stress magnitudes (determined within slip planes). Such shear stress and pressure rise variations are similar to those which would be present if the slip is induced by the intermolecular interactions which are associated with near-wall microscale effects. The present slip-roughness effects are quantified experimentally over rotational speeds from 50 to 1200 rpm, pressure increases from 0 to 312 kPa, net flow rates of 0-100 ?l/min, and fluid chamber heights from 6.85 to 29.2 ?m. Verification is provided by comparisons with analytic results determined from the rotating Couette flow forms of the Navier-Stokes equations, with different disk rotational speeds, disk roughness levels, and fluid chamber heights. These data show that slip length magnitudes show significant dependence on radial-line-averaged shear stress for average disk roughness heights of 404 and 770 nm. These slip length data additionally show a high degree of organization when normalized using by either the average roughness height or the fluid chamber height. For the latter case, such behavior provides evidence that the flow over a significant portion of the passage height is affected by the roughness, and near-wall slip velocities, especially when the average roughness height amounts to 11% of the h =6.86 ?m passage height of the channel. Such scaling of the disk slip length bdisk with fluid chamber height h is consistent with d-type roughness scaling in macroscale flows.

  6. Impeller flow field characterization with a laser two-focus velocimeter

    NASA Astrophysics Data System (ADS)

    Brozowski, L. A.; Ferguson, T. V.; Rojas, L.

    1993-07-01

    Use of Computational Fluid Dynamics (CFD) codes, prevalent in the rocket engine turbomachinery industry, necessitates data of sufficient quality and quantity to benchmark computational codes. Existing data bases for typical rocket engine configurations, in particular impellers, are limited. In addition, traditional data acquisition methods have several limitations: typically transducer uncertainties are 0.5% of transducer full scale and traditional pressure probes are unable to provide flow characteristics in the circumferential (blade-to-blade) direction. Laser velocimetry circumvents these limitations by providing +0.5% uncertainty in flow velocity and +0.5% uncertainty in flow angle. The percent of uncertainty in flow velocity is based on the measured value, not full range capability. The laser electronics multiple partitioning capability allows data acquired between blades as the impeller rotates, to be analyzed separately, thus providing blade-to-blade flow characterization. Unlike some probes, the non-intrusive measurements made with the laser velocimeter does not disturb the flow. To this end,, and under Contract (NAS8-38864) to the National Aeronautics and Space Administration (NASA) at Marshall Space Flight Center (MSFC), an extensive test program was undertaken at Rocketdyne. Impellers from two different generic rocket engine pump configurations were examined. The impellers represent different spectrums of pump design: the Space Shuttle Main Engine (SSME) high pressure fuel turbopump (HPFTP) impeller was designed in the 1 1970's the Consortium for CFD application in Propulsion Technology Pump Stage Technology Team (Pump Consortium) optimized impeller was designed with the aid of modern computing techniques. The tester configuration for each of the impellers consisted of an axial inlet, an inducer, a diffuser, and a crossover discharge. While the tested configurations were carefully chosen to be representative of generic rocket engine pumps, several features of both testers were intentionally atypical. A crossover discharge, downstream of the impeller, rather than a volute discharge was used to minimize asymmetric flow conditions that might be reflected in the impeller discharge flow data. Impeller shroud wear ring radial clearances were purposely close to minimize leakage flow, thus increasing confidence in using the inlet data as an input to CFD programs. The empirical study extensively examined the flow fields of the two impellers via performance of laser two-focus velocimeter surveys in an axial plane upstream of the impellers and in multiple radial planes downstream of the impellers. Both studies were performed at the impeller design flow coefficients. Inlet laser surveys that provide CFD code inlet boundary conditions were performed in one axial plane, with ten radial locations surveyed. Three wall static pressures, positioned circumferentially around the impeller inlet, were used to identify asymmetrical pressure distributions in the inlet survey plane. impeller discharge flow characterization consisted of three radial planes for the SSME HPFTP impeller and two radial planes for the Pump Consortium optimized impeller. &Housing wall static pressures were placed to correspond to the radial locations surveyed with the laser velocimeter. Between five and thirteen axial stations across the discharge channel width were examined in each radial plane during the extensive flow mapping. The largely successful empirical flow characterization of two different impellers resulted in a substantial contribution to the limited existing data base, and yielded accurate data for CFD code benchmarking.

  7. Noncavitating Pump For Liquid Helium

    NASA Technical Reports Server (NTRS)

    Hasenbein, Robert; Izenson, Michael; Swift, Walter; Sixsmith, Herbert

    1996-01-01

    Immersion pump features high efficiency in cryogenic service. Simple and reliable centrifugal pump transfers liquid helium with mass-transfer efficiency of 99 percent. Liquid helium drawn into pump by helical inducer, which pressurizes helium slightly to prevent cavitation when liquid enters impeller. Impeller then pressurizes liquid. Purpose of pump to transfer liquid helium from supply to receiver vessel, or to provide liquid helium flow for testing and experimentation.

  8. Impeller for Water Jet Propulsion

    NASA Technical Reports Server (NTRS)

    2004-01-01

    Marshall Space Flight Center engineers helped North American Marine Jet (NAMJ), Inc. improve the proposed design of a new impeller for jet propulsion system. With a three-dimensional computer model of the new marine jet engine blades, engineers were able to quickly create a solid ploycarbonate model of it. The rapid prototyping allowed the company to avoid many time-consuming and costly steps in creating the impeller.

  9. Impeller tandem blade study with grid embedding for local grid refinement

    NASA Technical Reports Server (NTRS)

    Bache, George

    1992-01-01

    Flow non-uniformity at the discharge of high power density impellers can result in significant unsteady interactions between impeller blades and downstream diffuser vanes. These interactions result in degradation of both performance and pump reliability. The MSFC Pump Technology Team has recognized the importance of resolving this problem and has thus initiated the development and testing of a high head coefficient impeller. One of the primary goals of this program is to improve impeller performance and discharge flow uniformity. The objective of the present work is complimentary. Flow uniformity and performance gains were sought through the application of a tandem blade arrangement. The approach adopted was to numerically establish flow characteristics at the impeller discharge for the baseline MSFC impeller and then parametrically evaluate tandem blade configurations. A tandem design was sought that improves both impeller performance and discharge uniformity. The Navier-Stokes solver AEROVISC was used to conduct the study. Grid embedding is used to resolve local gradients while attempting to minimize model size. Initial results indicate that significant gains in flow uniformity can be achieved through the tandem blade concept and that blade clocking rather than slot location is the primary driver for flow uniformity.

  10. Measuring axial pump thrust

    DOEpatents

    Suchoza, B.P.; Becse, I.

    1988-11-08

    An apparatus for measuring the hydraulic axial thrust of a pump under operation conditions is disclosed. The axial thrust is determined by forcing the rotating impeller off of an associated thrust bearing by use of an elongate rod extending coaxially with the pump shaft. The elongate rod contacts an impeller retainer bolt where a bearing is provided. Suitable measuring devices measure when the rod moves to force the impeller off of the associated thrust bearing and the axial force exerted on the rod at that time. The elongate rod is preferably provided in a housing with a heat dissipation mechanism whereby the hot fluid does not affect the measuring devices. 1 fig.

  11. Measuring axial pump thrust

    DOEpatents

    Suchoza, Bernard P. (McMurray, PA); Becse, Imre (Washington, PA)

    1988-01-01

    An apparatus for measuring the hydraulic axial thrust of a pump under operation conditions is disclosed. The axial thrust is determined by forcing the rotating impeller off of an associated thrust bearing by use of an elongate rod extending coaxially with the pump shaft. The elongate rod contacts an impeller retainer bolt where a bearing is provided. Suitable measuring devices measure when the rod moves to force the impeller off of the associated thrust bearing and the axial force exerted on the rod at that time. The elongate rod is preferably provided in a housing with a heat dissipation mechanism whereby the hot fluid does not affect the measuring devices.

  12. Numerical studies in a centrifugal pump with the improved blade considering cavitation

    NASA Astrophysics Data System (ADS)

    Song, P. F.; Zhang, Y. X.; Xu, C.; Zhou, X.; Zhang, J. Y.

    2015-01-01

    In this paper, a centrifugal pump with the improved blade for cavitation is studied numerically. A 3D impeller with logarithmic spiral blade profile was designed by the in-house hydraulic design code using a centrifugal pump geometric parameters, and the blade profile curve of suction side on the designed impeller is replaced by a combination of tangent line and circle arc line. The cavitation flows in the centrifugal pump with designed impeller, modified impeller and centrifugal pump spectrum impeller are respectively calculated by two-phase CFD simulation at three flow rates. The tests of the centrifugal pump have been conducted to verify numerical simulation. The effects of designed impeller and modified impeller on hydraulic efficiency, critical cavitation number, cavitation length, head drop performance and vapor cavity distribution in impeller are investigated. The results show that the modification of blade profile curve of suction side can improve the cavitation performance of an impeller and hydraulic efficiency of centrifugal pump. Compared with designed impeller, the critical cavitation number of centrifugal pump with modified impeller decrease by 26.5% under the same flow rate coefficient, and the cavitation intensity in the modified impeller is weakened effectively. The hydraulic efficiency of modified impeller also increases by 4.9%.

  13. Rotary blood pump

    NASA Technical Reports Server (NTRS)

    Bozeman, Richard J. (inventor); Akkerman, James W. (inventor); Aber, Greg S. (inventor); Vandamm, George A. (inventor); Bacak, James W. (inventor); Svejkovsky, Paul A. (inventor); Benkowski, Robert J. (inventor)

    1993-01-01

    A rotary blood pump is presented. The pump includes a pump housing for receiving a flow straightener, a rotor mounted on rotor bearings and having an inducer portion and an impeller portion, and a diffuser. The entrance angle, outlet angle, axial, and radial clearances of the blades associated with the flow straightener, inducer portion, impeller portion, and diffuser are optimized to minimize hemolysis while maintaining pump efficiency. The rotor bearing includes a bearing chamber that is filled with crosslinked blood or other bio-compatible material. A back emf integrated circuit regulates rotor operation and a microcomputer may be used to control one or more back emf integrated circuits. A plurality of magnets are disposed in each of a plurality of impeller blades with a small air gap. A stator may be axially adjusted on the pump housing to absorb bearing load and maximize pump efficiency.

  14. LH2 pump component development testing in the electric pump room at test cell C inducer no. 1

    NASA Technical Reports Server (NTRS)

    Andrews, F. X.; Brunner, J. J.; Kirk, K. G.; Mathews, J. P.; Nishioka, T.

    1972-01-01

    The characteristics of a turbine pump for use with the nuclear engine for rocket vehicles are discussed. It was determined that the pump will be a two stage centrifugal pump with both stages having backswept impellers and an inducer upstream of the first stage impeller. The test program provided demonstration of the ability of the selected design to meet the imposed requirements.

  15. Rotary Blood Pump

    NASA Technical Reports Server (NTRS)

    Bozeman, Richard J., Jr. (Inventor); Akkerman, James W. (Inventor); Aber, Gregory S. (Inventor); VanDamm, George A. (Inventor); Bacak, James W. (Inventor); Svejkovsky, Paul A. (Inventor); Benkowski, Robert J. (Inventor)

    1996-01-01

    A rotary blood pump includes a pump housing for receiving a flow straightener, a rotor mounted on rotor bearings and having an inducer portion and an impeller portion, and a diffuser. The entrance angle, outlet angle, axial and radial clearances of blades associated with the flow straightener, inducer portion, impeller portion and diffuser are optimized to minimize hemolysis while maintaining pump efficiency. The rotor bearing includes a bearing chamber that is filled with cross-linked blood or other bio-compatible material. A back emf integrated circuit regulates rotor operation and a microcomputer may be used to control one or more back emf integrated circuits. A plurality of magnets are disposed in each of a plurality of impeller blades with a small air gap. A stator may be axially adjusted on the pump housing to absorb bearing load and maximize pump efficiency.

  16. A finite element model of the turbulent flow field in a centrifugal impeller

    E-print Network

    Hlavaty, Steven Todd

    1993-01-01

    model. Their model was conceptually an extension of a duct- flow calculation procedure and is therefore less accurate as a result. Chima (1986) developed a quasi-three-dimensional analysis for the viscous flow in a centrifugal impeller, and Rai (1987... and Wake Development in a Centrifugal Impeller, " ASME Journal of Engineering for Power, Vol. 103, pp. 367-372. Rai, M. M. , 1987, "Three-Dimensional Navier-Stokes Simulations of Turbine Rotor-Stator Interaction, " AIAA Paper No. 87-2058. 47 VITA...

  17. Investigation of the axial and radial thrusts in a centrifugal pump 

    E-print Network

    Park, Chong Hwan

    1984-01-01

    Calibration Data (Test g2) ------------ 94 4 Pressure Distribution Measurements in a 3" x 4" Pump with Impeller Back-vanes Rotating at 1150 rpm 5 Pressure Distribution Measurements in a 3" x 4" Pump without Impeller Back-vance Rotating at 1150 rpm... Rate in a 6" x 8" Pump without Impeller Back-vanes Rotating at 1150 rpm---------- Page 90 91 NOMENCLATURE Alphabetical Ai As Be bhp Ca Cf Cq Ce area (in 2) area of impeller (in2) total impeller projected area (in 2) cross sectional...

  18. Pressure oscillation in the leakage annulus between a shrouded impeller and its housing due to impeller-discharge-pressure disturbances

    NASA Technical Reports Server (NTRS)

    Childs, D. W.

    1992-01-01

    The perturbed flow in the leakage path between a shrouded-pump impeller and its housing is analyzed using experiences with the Space Shuttle Main Engine (SSME), high pressure fuel turbopump (HPFTP) wearing-ring seals. Analysis is based on a bulk-flow model which consists of the path-momentum, circumferential momentum, and continuity equations. The pressure oscillations in the leakage annulus are driven by a circumferential variation of the impeller discharge pressure. It is shown that the occurrence and nature of the pressure oscillations depend on the tangential-velocity ratio of the fluid entering the seal, the order of the Fourier coefficient, the closeness of the precessional frequency of the rotating pressure field to the first natural frequency of the fluid annulus, and the clearance of the wearing-ring seal. The results obtained may explain the internal melting observed on SSME HPFTP seal parts.

  19. Scaling of impeller response to impeller-diffuser interactions in centrifugal compressors

    E-print Network

    Tarr, David Landon

    2008-01-01

    A numerical investigation has been conducted to quantify the effect of impeller-diffuser interaction on changes in impeller performance. An assessment is made of the hypothesis that the nondimensional parameter characterizing ...

  20. Oxygen mass transfer in a stirred tank bioreactor using different impeller configurations for environmental purposes

    PubMed Central

    2013-01-01

    In this study, a miniature stirred tank bioreactor was designed for treatment of waste gas containing benzene, toluene and xylene. Oxygen mass transfer characteristics for various twin and single-impeller systems were investigated for 6 configurations in a vessel with 10 cm of inner diameter and working volume of 1.77L. Three types of impellers, namely, Rushton turbine, Pitched 4blades and Pitched 2blades impellers with downward pumping have been used. Deionized water was used as a liquid phase. With respect to other independent variables such as agitation speed, aeration rate, type of sparger, number of impellers, the relative performance of these impellers was assessed by comparing the values of (KLa) as a key parameter. Based on the experimental data, empirical correlations as a function of the operational conditions have been proposed, to study the oxygen transfer rates from air bubbles generated in the bioreactor. It was shown that twin Rushton turbine configuration demonstrates superior performance (23% to 77% enhancement in KLa) compared with other impeller compositions and that sparger type has negligible effect on oxygen mass transfer rate. Agitation speeds of 400 to 800 rpm were the most efficient speeds for oxygen mass transfer in the stirred bioreactor. PMID:23369581

  1. Oxygen mass transfer in a stirred tank bioreactor using different impeller configurations for environmental purposes.

    PubMed

    Karimi, Ali; Golbabaei, Farideh; Mehrnia, Momammad Reza; Neghab, Masoud; Mohammad, Kazem; Nikpey, Ahmad; Pourmand, Mohammad Reza

    2013-01-01

    In this study, a miniature stirred tank bioreactor was designed for treatment of waste gas containing benzene, toluene and xylene. Oxygen mass transfer characteristics for various twin and single-impeller systems were investigated for 6 configurations in a vessel with 10 cm of inner diameter and working volume of 1.77L. Three types of impellers, namely, Rushton turbine, Pitched 4blades and Pitched 2blades impellers with downward pumping have been used. Deionized water was used as a liquid phase. With respect to other independent variables such as agitation speed, aeration rate, type of sparger, number of impellers, the relative performance of these impellers was assessed by comparing the values of (KLa) as a key parameter. Based on the experimental data, empirical correlations as a function of the operational conditions have been proposed, to study the oxygen transfer rates from air bubbles generated in the bioreactor. It was shown that twin Rushton turbine configuration demonstrates superior performance (23% to 77% enhancement in KLa) compared with other impeller compositions and that sparger type has negligible effect on oxygen mass transfer rate. Agitation speeds of 400 to 800 rpm were the most efficient speeds for oxygen mass transfer in the stirred bioreactor. PMID:23369581

  2. Comparison between predicted and experimentally measured flow fields at the exit of the SSME HPFTP impeller

    Microsoft Academic Search

    George Bache

    1993-01-01

    Validation of CFD codes is a critical first step in the process of developing CFD design capability. The MSFC Pump Technology Team has recognized the importance of validation and has thus funded several experimental programs designed to obtain CFD quality validation data. The first data set to become available is for the SSME High Pressure Fuel Turbopump Impeller. LDV Data

  3. Investigation of the axial and radial thrusts in a centrifugal pump

    E-print Network

    Park, Chong Hwan

    1984-01-01

    : Dr. Peter E. Jenkins Experiments have been performed to investigate the axial and radial thrusts in a centrifugal pump. The experiments were done with varying flow rates at two different speeds (1150rpm, 1750rpm), for two different impellers... Calibration Data (Test g2) ------------ 94 4 Pressure Distribution Measurements in a 3" x 4" Pump with Impeller Back-vanes Rotating at 1150 rpm 5 Pressure Distribution Measurements in a 3" x 4" Pump without Impeller Back-vance Rotating at 1150 rpm...

  4. AN OPTIMIZATION TECHNIQUE FOR RADIAL COMPRESSOR IMPELLERS

    Microsoft Academic Search

    Michael Casey; Frank Gersbach; Chris Robinson

    2008-01-01

    A software tool has been created to aid in automate d impeller design within an integrated design system for radial flow impellers. The design tool takes the results f rom the 1D preliminary design process and uses these to define a parameterized blade geometry, which incorporates features that are required for low mechanical stresses and s imple manufacturing. This geometry

  5. The Development of a Centrifugal Compressor Impeller

    Microsoft Academic Search

    C. Xu; R. S. Amano

    2009-01-01

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

  6. Use of partially shrouded impeller in a small centrifugal compressor

    NASA Astrophysics Data System (ADS)

    Tang, Jin; Turunen-Saaresti, Teemu; Larjola, Jaakko

    2008-03-01

    Numerical analysis is conducted for the 3-dimensional impeller and vaneless diffuser of a small centrifugal compressor. The influence of impeller tip clearance on the flow field of the impeller is investigated. Detailed investigation on the leaking flow across the tip clearance of the impeller shows that the leaking flow rate is higher near the exit of the impeller than that near the inlet of the impeller. Based on this phenomenon, a new partially shrouded impeller is designed. The impeller is shrouded near the exit of the impeller. Numerical results show that the secondary flow region becomes smaller at the exit of the impeller. Better performance is achieved than that with the unshrouded impeller.

  7. Magnetically suspended miniature fluid pump and method of designing the same

    NASA Technical Reports Server (NTRS)

    Antaki, James F. (Inventor); Paden, Bradley (Inventor); Burgreen, Gregory (Inventor); Groom, Nelson (Inventor)

    2000-01-01

    A rotary pump for pumping fluids through a patient having a housing with an internal region, a stator member and an impeller positioned within the housing and having impeller blades, wherein the impeller is magnetically suspended and rotated, and wherein the geometric configuration of the rotary pump is sized and proportioned to minimize stagnant and traumatic fluid flow within the rotary pump. The plurality of magnetic impeller blades are preferably rare earth, high-energy-density magnets selected from the group consisting of samarium cobalt and neodymium-iron-boron alloy.

  8. Pump CFD code validation tests

    NASA Technical Reports Server (NTRS)

    Brozowski, L. A.

    1993-01-01

    Pump CFD code validation tests were accomplished by obtaining nonintrusive flow characteristic data at key locations in generic current liquid rocket engine turbopump configurations. Data were obtained with a laser two-focus (L2F) velocimeter at scaled design flow. Three components were surveyed: a 1970's-designed impeller, a 1990's-designed impeller, and a four-bladed unshrouded inducer. Two-dimensional velocities were measured upstream and downstream of the two impellers. Three-dimensional velocities were measured upstream, downstream, and within the blade row of the unshrouded inducer.

  9. Energy efficiency study on axial flow impellers

    Microsoft Academic Search

    Jie Wu; Lachlan J. Graham; Bon Nguyen; M. Nabil Noui Mehidi

    2006-01-01

    Theoretical equations are developed to relate the flow velocities in a tank with impeller power consumption, flow circulation efficiency index NQ\\/P01\\/3 and other parameters. A non-dimensional parameter ?=V\\/((P\\/(?T2))1\\/3) has been used to characterise the velocity energy efficiency. Laser Doppler velocimetry measurement studies were carried out on the flow field produced by a few commercial axial flow hydrofoil impellers and pitch

  10. Experimental and dynamic system simulation and optimization of a centrifugal pump-coupling-engine system. Part 1: Failure identification

    Microsoft Academic Search

    F. Jiménez Espadafor; J. Becerra Villanueva; M. Torres García; E. Carvajal Trujillo

    2011-01-01

    The failure mode of the six impellers of a centrifugal pump in an irrigation system used for street washing has been analyzed. The irrigation system is installed in more than 300 vehicles and consists of a pump, a tank, a regulator valve and the piping network. The was caused by a premature deterioration of the pump impellers in the water

  11. Orthogonal test and experimental study on fire floating pump

    NASA Astrophysics Data System (ADS)

    Liu, J. R.; Zheng, J. F.; Fu, D. P.; Wang, P.

    2013-12-01

    In order to develop high efficiency fire floating pump, 250YYB-250 fire floating pump was taken as an example. The orthogonal experiment of L9 (34), which contains factors with three levels of blade numbers of impeller, outlet angle, impeller fold-angle, was performed to design nine types of impellers. Numerical simulation of whole flow field based on Fluent was adopted to perform an orthogonal test, the order of geometric parameters affects the performance of fire floating pump with complex impeller. The best design scheme for pump model was acquired. Meanwhile, the optimized design scheme was determined, and corresponding test was carried out. It demonstrated that the efficiency of the final optimal design model pump at rated flow point is of 85%. The efficiency is higher than the national standards, which verified the feasibility of the method of orthogonal design in pump design.

  12. Single-disk and double-disk viscous micropumps

    Microsoft Academic Search

    Danny Blanchard; Phil Ligrani; Bruce Gale

    2005-01-01

    The development and testing of two versions of a novel micropump are described: (i) the single-disk viscous pump and (ii) the double-disk viscous pump. The rotational movement of the disk(s) induces viscous stresses on the fluid that forces the fluid from an inlet channel, and then, through the pumping volume above the single disk, or between the two disks. A

  13. Flow Pattern Characterization for a Centrifugal Impeller

    NASA Astrophysics Data System (ADS)

    Benavides, Efrén M.

    2014-08-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

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

  15. Near net shape forming process of a titanium alloy impeller

    Microsoft Academic Search

    K. Shi; D. B. Shan; W. C. Xu; Y. Lu

    2007-01-01

    The complex components such as the impellers are difficult to manufacture because of their complicated shapes and high requirements of mechanical properties. In order to form the titanium impeller precisely two forming schemes with two die devices were designed. Three-dimensional finite element method (FEM) was used to simulate the forming process of the impeller and study the metal flow laws.

  16. Experimental and computational results from a large low-speed centrifugal impeller

    NASA Technical Reports Server (NTRS)

    Hathaway, M. D.; Chriss, R. M.; Wood, J. R.; Strazisar, A. J.

    1994-01-01

    An experimental and computational investigation of the NASA Low-Speed Centrifugal Compressor (LSCC) flow field was conducted using laser anemometry and Dawes' 3D viscous code. The experimental configuration consists of a back-swept impeller followed by a vaneless diffuser. Measurements of the three-dimensional velocity field were acquired at several measurement planes through the compressor. The measurements describe both the throughflow and secondary velocity field along each measurement plane and, in several cases, provide details of the flow within the blade boundary layers. The experimental and computational results provide a clear understanding of the development of the throughflow momentum wake which is characteristic of centrifugal compressors.

  17. Experimental and computational results from a large low-speed centrifugal impeller

    NASA Technical Reports Server (NTRS)

    Hathaway, M. D.; Chriss, R. M.; Wood, J. R.; Strazisar, A. J.

    1993-01-01

    An experimental and computational investigation of the NASA Low-Speed Centrifugal Compressor (LSCC) flow field has been conducted using laser anemometry and Dawes' 3D viscous code. The experimental configuration consists of a backswept impeller followed by a vaneless diffuser. Measurements of the three-dimensional velocity field were acquired at several measurement planes through the compressor. The measurements describe both the throughflow and secondary velocity field along each measurement plane and in several cases provide details of the flow within the blade boundary layers. The experimental and computational results provide a clear understanding of the development of the throughflow momentum wake which is characteristic of centrifugal compressors.

  18. Submersible canned motor transfer pump

    DOEpatents

    Guardiani, Richard F. (Ohio Township, Allegheny County, PA); Pollick, Richard D. (Sarver, PA); Nyilas, Charles P. (Monroeville, PA); Denmeade, Timothy J. (Lower Burrell, PA)

    1997-01-01

    A transfer pump used in a waste tank for transferring high-level radioactive liquid waste from a waste tank and having a column assembly, a canned electric motor means, and an impeller assembly with an upper impeller and a lower impeller connected to a shaft of a rotor assembly. The column assembly locates a motor housing with the electric motor means adjacent to the impeller assembly which creates an hydraulic head, and which forces the liquid waste, into the motor housing to cool the electric motor means and to cool and/or lubricate the radial and thrust bearing assemblies. Hard-on-hard bearing surfaces of the bearing assemblies and a ring assembly between the upper impeller and electric motor means grind large particles in the liquid waste flow. Slots in the static bearing member of the radial bearing assemblies further grind down the solid waste particles so that only particles smaller than the clearances in the system can pass therethrough, thereby resisting damage to and the interruption of the operation of the transfer pump. The column assembly is modular so that sections can be easily assembled, disassembled and/or removed. A second embodiment employs a stator jacket which provides an alternate means for cooling the electric motor means and lubricating and/or cooling the bearing assemblies, and a third embodiment employs a variable level suction device which allows liquid waste to be drawn into the transfer pump from varying and discrete levels in the waste tank.

  19. Method for Reducing Pumping Damage to Blood

    NASA Technical Reports Server (NTRS)

    Bozeman, Richard J., Jr. (Inventor); Akkerman, James W. (Inventor); Aber, Gregory S. (Inventor); VanDamm, George Arthur (Inventor); Bacak, James W. (Inventor); Svejkovsky, Robert J. (Inventor); Benkowski, Robert J. (Inventor)

    1997-01-01

    Methods are provided for minimizing damage to blood in a blood pump wherein the blood pump comprises a plurality of pump components that may affect blood damage such as clearance between pump blades and housing, number of impeller blades, rounded or flat blade edges, variations in entrance angles of blades, impeller length, and the like. The process comprises selecting a plurality of pump components believed to affect blood damage such as those listed herein before. Construction variations for each of the plurality of pump components are then selected. The pump components and variations are preferably listed in a matrix for easy visual comparison of test results. Blood is circulated through a pump configuration to test each variation of each pump component. After each test, total blood damage is determined for the blood pump. Preferably each pump component variation is tested at least three times to provide statistical results and check consistency of results. The least hemolytic variation for each pump component is preferably selected as an optimized component. If no statistical difference as to blood damage is produced for a variation of a pump component, then the variation that provides preferred hydrodynamic performance is selected. To compare the variation of pump components such as impeller and stator blade geometries, the preferred embodiment of the invention uses a stereolithography technique for realizing complex shapes within a short time period.

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

    NASA Technical Reports Server (NTRS)

    Tan, Choon S.

    2003-01-01

    This research program focuses on characterizing the effect of impeller-diffuser interactions in a centrifugal compressor stage on its performance using unsteady threedimensional Reynolds-averaged Navier-Stokes simulations. The computed results show that the interaction between the downstream diffuser pressure field and the impeller tip clearance flow can account for performance changes in the impeller. The magnitude of performance change due to this interaction was examined for an impeller with varying tip clearance followed by a vaned or vaneless diffuser. The impact of unsteady impeller-diffuser interaction, primarily through the impeller tip clearance flow, is reflected through a time-averaged change in impeller loss, blockage and slip. The results show that there exists a tip clearance where the beneficial effect of the impeller-diffuser interaction on the impeller performance is at a maximum. A flow feature that consists of tip flow back leakage was shown to occur at design speed for the centrifugal compressor stage. This flow phenomenon is described as tip flow that originates in one passage, flows downstream of the impeller trailing edge and then returns to upstream of the impeller trailing edge of a neighboring passage. Such a flow feature is a source of loss in the impeller. A hypothesis is put forth to show that changing the diffuser vane count and changing impeller-diffuser gap has an analogous effect on the impeller performance. The centrifugal compressor stage was analyzed using diffusers of different vane counts, producing an impeller performance trend similar to that when the impeller-diffuser gap was varied, thus supporting the hypothesis made. This has the implication that the effect impeller performance associated with changing the impeller-diffuser gap and changing diffuser vane count can be described by the non-dimensional ratio of impeller-diffuser gap to diffuser vane pitch. A procedure is proposed and developed for isolating impeller passage blockage change without the need to define the region of blockage generation (which may incur a certain degree of arbitrariness). This method has been assessed for its applicability and utility.

  1. Leachate and condensate pumping system

    SciTech Connect

    Bertane, M. [Blackhawk Environmental, Glen Ellyn, IL (United States)

    1995-12-31

    The Blackhawk Anchor Pump is an air or electrically driven pumping system. it uses old pumping methods in a new and innovative way to solve the difficult problems of recovering contaminated water, leachate, or hard to handle, difficult liquids. The Anchor Pump pumps down to 0 submergence. It pumps hot or viscous liquids. Being a positive displacement pump, all the energy of the system is directed a the point of pumping. The Anchor Pump motor is at surface grade and can pump vertically or horizontally. The Anchor Pump has proven its effectiveness in the field recovering landfill leachate and condensate.

  2. Variable Speed Pumping for Level Control

    E-print Network

    Vasel, M.

    1982-01-01

    100 I- 9" 80 60 '10 20 At this juncture, we go to the pump performance curves illustrated in Figure 3, which are in a range that fit our requirements. Typically a number of different impeller sizes are available for a common pump housing. We... choose a standard Goulds Model 3196 centrifugal pump. Our design point of 131 TDH at 125 GPM flow dictates the use of an 11-1/2 inch impeller, with a resulting efficiency of 50%. Standard design practice would indicate a 15 HP motor requirement...

  3. Prognostics of slurry pumps based on a moving-average wear degradation index and a general sequential Monte Carlo method

    NASA Astrophysics Data System (ADS)

    Wang, Dong; Tse, Peter W.

    2015-05-01

    Slurry pumps are commonly used in oil-sand mining for pumping mixtures of abrasive liquids and solids. These operations cause constant wear of slurry pump impellers, which results in the breakdown of the slurry pumps. This paper develops a prognostic method for estimating remaining useful life of slurry pump impellers. First, a moving-average wear degradation index is proposed to assess the performance degradation of the slurry pump impeller. Secondly, the state space model of the proposed health index is constructed. A general sequential Monte Carlo method is employed to derive the parameters of the state space model. The remaining useful life of the slurry pump impeller is estimated by extrapolating the established state space model to a specified alert threshold. Data collected from an industrial oil sand pump were used to validate the developed method. The results show that the accuracy of the developed method improves as more data become available.

  4. An improved theory for regenerative pump performance

    E-print Network

    Kim, Yong Jung

    and it can be used for the design of twisted blades that would increase the pump head and efficiency. A new, impeller angles, CFD 1 INTRODUCTION Regenerative flow pumps and compressors have found many applications of publications existing in the literature is comparatively less than papers dealing with centrifugal and axial

  5. Dynamics of a high speed impeller - Analysis and experimental verification

    NASA Astrophysics Data System (ADS)

    Straub, F. K.; Ngo, H.; Silverthorn, L. J.; Ruopsa, J. A.

    1993-04-01

    Centrifugal compressors are used on numerous aircraft as an efficient and lightweight source of air. The impeller is the key compressor component, both from an aerodynamic and structural dynamics point of view. The present paper investigates the structural dynamics of the blades of a particular impeller, using analytical and experimental methods. Correlation of results show good agreement. The analytical model is then used for design studies to improve the fatigue life of the impeller blades.

  6. Fault-tolerant strategies for an implantable centrifugal blood pump using a radially controlled magnetic bearing.

    PubMed

    Pai, Chi Nan; Shinshi, Tadahiko

    2011-10-01

    In our laboratory, an implantable centrifugal blood pump (CBP) with a two degrees-of-freedom radially controlled magnetic bearing (MB) to support the impeller without contact has been developed to assist the pumping function of the weakened heart ventricle. In order to maintain the function of the CBP after damage to the electromagnets (EMs) of the MB, fault-tolerant strategies for the CBP are proposed in this study. Using a redundant MB design, magnetic levitation of the impeller was maintained with damage to up to two out of a total of four EMs of the MB; with damage to three EMs, contact-free support of the impeller was achieved using hydrodynamic and electromagnetic forces; and with damage to all four EMs, the pump operating point, of 5 l/min against 100 mmHg, was achieved using the motor for rotation of the impeller, with contact between the impeller and the stator. PMID:21382738

  7. Multiple discharge cylindrical pump collector

    DOEpatents

    Dunn, Charlton (Calabasas, CA); Bremner, Robert J. (Woodland Hills, CA); Meng, Sen Y. (Reseda, CA)

    1989-01-01

    A space-saving discharge collector 40 for the rotary pump 28 of a pool-type nuclear reactor 10. An annular collector 50 is located radially outboard for an impeller 44. The annular collector 50 as a closed outer periphery 52 for collecting the fluid from the impeller 44 and producing a uniform circumferential flow of the fluid. Turning means comprising a plurality of individual passageways 54 are located in an axial position relative to the annular collector 50 for receiving the fluid from the annular collector 50 and turning it into a substantially axial direction.

  8. Satellite Propellant Pump Research

    NASA Technical Reports Server (NTRS)

    Schneider, Steven J.; Veres, Joseph P.; Hah, Chunill; Nerone, Anthony L.; Cunningham, Cameron C.; Kraft, Thomas G.; Tavernelli, Paul F.; Fraser, Bryan

    2005-01-01

    NASA Glenn initiated a satellite propellant pump technology demonstration program. The goal was to demonstrate the technologies for a 60 percent efficient pump at 1 gpm flow rate and 500 psia pressure rise. The pump design and analysis used the in-house developed computer codes named PUMPA and HPUMP3D. The requirements lead to a 4-stage impeller type pump design with a tip diameter of 0.54 inches and a rotational speed of 57,000 rpm. Analyses indicated that flow cavitation was not a problem in the design. Since the flow was incompressible, the stages were identical. Only the 2-stage pump was designed, fabricated, assembled, and tested for demonstration. Water was selected as the surrogate fluid for hydrazine in this program. Complete mechanical design including stress and dynamic analyses were conducted. The pump was driven by an electric motor directly coupled to the impellers. Runs up to 57,000 rpm were conducted, where a pressure rise of 200 psia at a flow rate of 0.8 gpm was measured to validate the design effort.

  9. Dynamics of a high speed impeller - Analysis and experimental verification

    Microsoft Academic Search

    F. K. Straub; H. Ngo; L. J. Silverthorn; J. A. Ruopsa

    1993-01-01

    Centrifugal compressors are used on numerous aircraft as an efficient and lightweight source of air. The impeller is the key compressor component, both from an aerodynamic and structural dynamics point of view. The present paper investigates the structural dynamics of the blades of a particular impeller, using analytical and experimental methods. Correlation of results show good agreement. The analytical model

  10. Fluid forces on rotating centrifugal impeller with whirling motion

    NASA Technical Reports Server (NTRS)

    Shoji, H.; Ohashi, H.

    1980-01-01

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

  11. Incompressible Navier-Stokes calculations in pump flows

    NASA Astrophysics Data System (ADS)

    Kiris, Cetin; Chang, Leon; Kwak, Dochan

    1993-07-01

    Flow through pump components, such as the SSME-HPFTP Impeller and an advanced rocket pump impeller, is efficiently simulated by solving the incompressible Navier-Stokes equations. The solution method is based on the pseudo compressibility approach and uses an implicit-upwind differencing scheme together with the Gauss-Seidel line relaxation method. The equations are solved in steadily rotating reference frames and the centrifugal force and the Coriolis force are added to the equation of motion. Current computations use one-equation Baldwin-Barth turbulence model which is derived from a simplified form of the standard k-epsilon model equations. The resulting computer code is applied to the flow analysis inside an 11-inch SSME High Pressure Fuel Turbopump impeller, and an advanced rocket pump impeller. Numerical results of SSME-HPFTP impeller flow are compared with experimental measurements. In the advanced pump impeller, the effects of exit and shroud cavities are investigated. Flow analyses at design conditions will be presented.

  12. Axial length influence on the performance of centrifugal impellers

    NASA Astrophysics Data System (ADS)

    Al-Zubaidy, S. N. J.

    1992-12-01

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

  13. Optimization of integrated impeller mixer via radiotracer experiments.

    PubMed

    Othman, N; Kamarudin, S K; Takriff, M S; Rosli, M I; Engku Chik, E M F; Adnan, M A K

    2014-01-01

    Radiotracer experiments are carried out in order to determine the mean residence time (MRT) as well as percentage of dead zone, V dead (%), in an integrated mixer consisting of Rushton and pitched blade turbine (PBT). Conventionally, optimization was performed by varying one parameter and others were held constant (OFAT) which lead to enormous number of experiments. Thus, in this study, a 4-factor 3-level Taguchi L9 orthogonal array was introduced to obtain an accurate optimization of mixing efficiency with minimal number of experiments. This paper describes the optimal conditions of four process parameters, namely, impeller speed, impeller clearance, type of impeller, and sampling time, in obtaining MRT and V dead (%) using radiotracer experiments. The optimum conditions for the experiments were 100 rpm impeller speed, 50 mm impeller clearance, Type A mixer, and 900 s sampling time to reach optimization. PMID:24741344

  14. Submersible canned motor mixer pump

    DOEpatents

    Guardiani, Richard F. (Ohio Township, PA); Pollick, Richard D. (Sarver, PA)

    1997-01-01

    A mixer pump used in a waste tank for mobilizing high-level radioactive liquid waste having a column assembly containing power cables, a motor housing with electric motor means which includes a stator can of a stator assembly and a rotor can of a rotor assembly, and an impeller assembly with an impeller connected to a shaft of the rotor assembly. The column assembly locates the motor housing with the electric motor means adjacent to the impeller which creates an hydraulic head, and which forces the liquid waste into the motor housing to cool the electric motor means and to lubricate radial and thrust bearing assemblies. Hard-on-hard bearing surfaces of the bearing assemblies and a ring assembly between the impeller and electric motor means act to grind down large particles in the liquid waste flow. These larger particles are received in slots in the static bearing members of the radial bearing assemblies. Only solid waste particles smaller than the clearances in the system can pass therethrough, thereby resisting damage to and the interruption of the operation of the mixer pump.

  15. Gas-liquid dispersion with dual Rushton turbine impellers.

    PubMed

    Hudcova, V; Machon, V; Nienow, A W

    1989-08-20

    Aerated and unaerated power consumption and flow patterns in a 0.56 m diameter agitated vessel containing water with dual Rushton turbines have been studied. Under unaerated conditions with a liquid height-to-diameter ratio of 2, an impeller spacing of 2 to 3 times the impeller is required for each to draw an amount of power equal to a single impeller. For aerated conditions, if a similar spacing is used, equations for the flooding-loading transition and for power consumption for a single Rushton impeller can be extended relatively easily to dual systems. All results for this spacing are explained by reference to bulk flow patterns and gassed-filled cavity structures and the proportion of sparged gas flowing through the upper impeller is also estimated. Such a spacing is generally recommended since it maximizes the power draw and hence the potential for oxygen mass transfer. Data are presented for other spacings but the results do not fit in easily with single agitator studies because strong impeller-impeller flow pattern interactions occur. PMID:18588146

  16. Analysis of Viscous Micropumps and Microturbines David DeCourtye

    E-print Network

    Gad-el-Hak, Mohamed

    Analysis of Viscous Micropumps and Microturbines David DeCourtye Mihir Sen Mohamed Gad to emphasize, however, that mechanical pumps based on conventional centrifugal or axial turbomachinery or less.1 There, viscous forces dominate in relation to inertia. Centrifugal forces are negligible and

  17. Research on 3-D discharge flow in a centrifugal impeller

    NASA Astrophysics Data System (ADS)

    Xi, Guang; Wang, Shangjin

    1993-01-01

    A method for calculating 3D discharge flow in a centrifugal impeller is developed by means of solving the incompressible steady time-averaged N-S equations, the continuity equation, and the k-epsilon turbulence model equation. This method is accomplished with calculation grids generated by an algebraic transformation, and thus it can be easily applied to the design analysis of centrifugal impellers. The discharge flow of a three-dimensional shrouded centrifugal compressor impeller was measured for assessing the validity of the present calculation procedure. The comparison between the experimental data and the calculation results shows that the present method can predict the mean velocities.

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

    NASA Astrophysics Data System (ADS)

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

    2015-01-01

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

  19. Use minimum flow data to prolong centrifugal pump life

    Microsoft Academic Search

    1996-01-01

    Environmental and safety concerns and, in the US, the consequences of failing of meet EPA regulations are intensifying efforts to improve the reliability of pumping equipment. A critical step toward achieving this goal is eliminating cavitation, and the resulting impeller and shaft vibrations, which, ultimately, cause seal and bearing failure. In centrifugal pumps, cavitation results when they run at very

  20. Performance characteristics of hydraulic turbines and pumps. Proceedings of the Winter annual meeting, Boston, MA, November 13-18, 1983

    SciTech Connect

    Bennett, G. Jr.; Rohatgi, U.S.; Swift, W.L.

    1983-01-01

    Various topics are addressed under the headings: four quadrant and two-phase performance of turbines and pumps, cavitation in hydraulic turbines and pumps, pumps as power recovery turbines, and modeling and fluid dynamics in hydraulic turbines and pumps. Individual subjects considered include: representation of pump characteristics for transient analysis, prediction and measurement of the four-quadrant performance of an axial flow pump of specific speed 8900, hydraulic analysis on component losses of centrifugal pumps. Also discussed are: effects of volute geometry and impeller orbit on the hydraulic performance of a centrifugal pump, interaction between impeller and volute of pumps at off-design conditions, performance of small high-speed pumps, relation between efficiency characteristics and the internal flow conditions of axial-flow pumps, tests of SSME low-pressure pump in liquids at a zero throughflow, and analysis of performance characteristics of axial flow pumps.

  1. 27. LEUPOLD AND STEVENS MIDGET CURRENT METER (WITH ALTERNATE IMPELLER) ...

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

    27. LEUPOLD AND STEVENS MIDGET CURRENT METER (WITH ALTERNATE IMPELLER) AND FOLDING SCALE (MEASURED IN INCHES). - Waterways Experiment Station, Hydraulics Laboratory, Halls Ferry Road, 2 miles south of I-20, Vicksburg, Warren County, MS

  2. Impeller loss reduction in multi-stage centrifugal compressors

    E-print Network

    Barile, Kristina (Kristina Marie)

    2015-01-01

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

  3. Numerical Investigations of Slip Phenomena in Centrifugal Compressor Impellers

    NASA Astrophysics Data System (ADS)

    Huang, Jeng-Min; Luo, Kai-Wei; Chen, Ching-Fu; Chiang, Chung-Ping; Wu, Teng-Yuan; Chen, Chun-Han

    2013-03-01

    This study systematically investigates the slip phenomena in the centrifugal air compressor impellers by CFD. Eight impeller blades for different specific speeds, wrap angles and exit blade angles are designed by compressor design software to analyze their flow fields. Except for the above three variables, flow rate and number of blades are the other two. Results show that the deviation angle decreases as the flow rate increases. The specific speed is not an important parameter regarding deviation angle or slip factor for general centrifugal compressor impellers. The slip onset position is closely related to the position of the peak value in the blade loading factor distribution. When no recirculation flow is present at the shroud, the variations of slip factor under various flow rates are mainly determined by difference between maximum blade angle and exit blade angle, ??max-2. The solidity should be of little importance to slip factor correlations in centrifugal compressor impellers.

  4. Design of a Bearingless Blood Pump

    NASA Technical Reports Server (NTRS)

    Barletta, Natale; Schoeb, Reto

    1996-01-01

    In the field of open heart surgery, centrifugal blood pumps have major advantages over roller pumps. The main drawbacks to centrifugal pumps are however problems with the bearings and with the sealing of the rotor shaft. In this paper we present a concept for a simple, compact and cost effective solution for a blood pump with a totally magnetically suspended impeller. It is based on the new technology of the 'Bearingless Motor' and is therefore called the 'Bearingless Blood Pump.' A single bearingless slice motor is at the same time a motor and a bearing system and is able to stabilize the six degrees of freedom of the pump impeller in a very simple way. Three degrees of freedom are stabilized actively (the rotation and the radial displacement of the motor slice). The axial and the angular displacement are stabilized passively. The pump itself (without the motor-stator and the control electronics) is built very simply. It consists of two parts only: the impeller with the integrated machine rotor and the housing. So the part which gets in contact with blood and has therefore to be disposable, is cheap. Fabricated in quantities, it will cost less than $10 and will therefore be affordable for the use in a heart-lung-machine.

  5. Investigation of flow in centrifugal impeller with tandem inducer

    E-print Network

    Nishida, Akira

    1976-01-01

    INVESTIGATION OF FLOW IN CENTRIFUGAL IMPELLER WITH TANDEM INDUCER A Thesis by AKIRA NISHIDA Submitted to the Graduate College of Texas A&M University in partial fulfillment of the requirement for the degree of MASTER OF SCIENCE August 1976... Major Subject: Mechanical Engineering INVESTIGATION OF FLOW IN CENTRIFUGAL IMPELLER WITH TANDEM INDUCER A Thesis by AKIRA NISHIDA P&~ (Chairman of C ittee) (Head of Department) (Member) (Member) Ld 4(? (Member) (Member) August 1976 AOSTRACT...

  6. Numerical simulation of impeller-volute interaction in centrifugal compressors

    Microsoft Academic Search

    K. Hillewaert; R. A. Van den Braembussche

    1999-01-01

    A numerical procedure to predict the impeller-volute interaction in a single-stage centrifugal compressor is presented. The method couples a three-dimensional unsteady flow calculation in the impeller with a three-dimensional time-averaged flow calculation in the volute through an iterative updating of the boundary conditions on the interface of both calculation domains. The method has been used to calculate the flow in

  7. Effects of tip clearance and impeller geometry on the performance of semi-open ceramic centrifugal fan impellers at elevated temperatures

    Microsoft Academic Search

    Tahsin Engin; Mesut Gur; Reinhard Scholz

    2006-01-01

    Centrifugal fans are being widely used in many industrial applications. However, when handling gases with temperatures exceeding 800°C, the use of centrifugal fan impellers are of particular interest since the conventional steel impellers would not be operated at such elevated temperatures. In the present experimental study, three semi-open centrifugal fan impellers have been designed and fabricated using ceramic materials to

  8. Motor-pump aggregate

    SciTech Connect

    Schneider, W.; Gaffal, K.; Peters, J.

    1983-10-04

    A motor-pump aggregate whose pump is a glandless centrifugal pump and is intended for use in a nuclear reactor plant has hollow coaxial pump and motor shafts which are sealingly coupled to each other. To this end, the first end portion of the pump shaft extends into the adjacent first end portion of the motor shaft and has an external conical shoulder for engagement with an internal conical seat of the first end portion of the motor shaft. A feather holds the first end portions against rotation relative to one another, and the shoulder is urged against the seat by a pair of threaded connectors one of which is anchored in a disc-shaped member in the region of the second end portion of the motor shaft and the other of which is anchored in the first end portion of the pump shaft. The disc-shaped member and the second end portion of the motor shaft have mating ring gears to ensure accurate and a reproducible centering. The connection between the second end portion of the pump shaft and an impeller is similar to that between the second end portion of the motor shaft and the disc-shaped member except that one of the respective connectors is anchored in a transverse end wall which is inserted into the second end portion of and is welded to the pump shaft.

  9. Computational fluid dynamic design of rocket engine pump components

    NASA Technical Reports Server (NTRS)

    Chen, Wei-Chung; Prueger, George H.; Chan, Daniel C.; Eastland, Anthony H.

    1992-01-01

    Integration of computational fluid dynamics (CFD) for design and analysis of turbomachinery components is needed as the requirements of pump performance and reliability become more stringent for the new generation of rocket engine. A fast grid generator, designed specially for centrifugal pump impeller, which allows a turbomachinery designer to use CFD to optimize the component design will be presented. The CFD grid is directly generated from the impeller blade G-H blade coordinates. The grid points are first generated on the meridional plane with the desired clustering near the end walls. This is followed by the marching of grid points from the pressure side of one blade to the suction side of a neighboring blade. This fast grid generator has been used to optimize the consortium pump impeller design. A grid dependency study has been conducted for the consortium pump impeller. Two different grid sizes, one with 10,000 grid points and one with 80,000 grid points were used for the grid dependency study. The effects of grid resolution on the turnaround time, including the grid generation and completion of the CFD analysis, is discussed. The impeller overall mass average performance is compared for different designs. Optimum design is achieved through systematic change of the design parameters. In conclusion, it is demonstrated that CFD can be effectively used not only for flow analysis but also for design and optimization of turbomachinery components.

  10. Fluid pumping apparatus

    DOEpatents

    West, Phillip B. (Idaho Falls, ID)

    2006-01-17

    A method and apparatus suitable for coupling seismic or other downhole sensors to a borehole wall in high temperature and pressure environments. In one embodiment, one or more metal bellows mounted to a sensor module are inflated to clamp the sensor module within the borehole and couple an associated seismic sensor to a borehole wall. Once the sensing operation is complete, the bellows are deflated and the sensor module is unclamped by deflation of the metal bellows. In a further embodiment, a magnetic drive pump in a pump module is used to supply fluid pressure for inflating the metal bellows using borehole fluid or fluid from a reservoir. The pump includes a magnetic drive motor configured with a rotor assembly to be exposed to borehole fluid pressure including a rotatable armature for driving an impeller and an associated coil under control of electronics isolated from borehole pressure.

  11. Diagnosis of Centrifugal Pump Faults Using Vibration Methods

    NASA Astrophysics Data System (ADS)

    Albraik, A.; Althobiani, F.; Gu, F.; Ball, A.

    2012-05-01

    Pumps are the largest single consumer of power in industry. This means that faulty pumps cause a high rate of energy loss with associated performance degradation, high vibration levels and significant noise radiation. This paper investigates the correlations between pump performance parameters including head, flow rate and energy consumption and surface vibration for the purpose of both pump condition monitoring and performance assessment. Using an in-house pump system, a number of experiments have been carried out on a centrifugal pump system using five impellers: one in good condition and four others with different defects, and at different flow rates for the comparison purposes. The results have shown that each defective impeller performance curve (showing flow, head, efficiency and NPSH (Net Positive Suction Head) is different from the benchmark curve showing the performance of the impeller in good condition. The exterior vibration responses were investigated to extract several key features to represent the healthy pump condition, pump operating condition and pump energy consumption. In combination, these parameter allow an optimal decision for pump overhaul to be made [1].

  12. Numerical simulation of pump-intake vortices

    NASA Astrophysics Data System (ADS)

    Rudolf, Pavel; Klas, Roman

    2015-05-01

    Pump pre-swirl or uneven flow distribution in front of the pump can induce pump-intake vortices. These phenomena result in blockage of the impeller suction space, deterioration of efficiency, drop of head curve and earlier onset of cavitation. Real problematic case, where head curve drop was documented, is simulated using commercial CFD software. Computational simulation was carried out for three flow rates, which correspond to three operating regimes of the vertical pump. The domain consists of the pump sump, pump itself excluding the impeller and the delivery pipe. One-phase approach is applied, because the vortex cores were not filled with air during observation of the real pump operation. Numerical simulation identified two surface vortices and one bottom vortex. Their position and strength depend on the pump flow rate. Paper presents detail analysis of the flow field on the pump intake, discusses influence of the vortices on pump operation and suggests possible actions that should be taken to suppress the intake vortices.

  13. A relevance vector machine-based approach with application to oil sand pump prognostics.

    PubMed

    Hu, Jinfei; Tse, Peter W

    2013-01-01

    Oil sand pumps are widely used in the mining industry for the delivery of mixtures of abrasive solids and liquids. Because they operate under highly adverse conditions, these pumps usually experience significant wear. Consequently, equipment owners are quite often forced to invest substantially in system maintenance to avoid unscheduled downtime. In this study, an approach combining relevance vector machines (RVMs) with a sum of two exponential functions was developed to predict the remaining useful life (RUL) of field pump impellers. To handle field vibration data, a novel feature extracting process was proposed to arrive at a feature varying with the development of damage in the pump impellers. A case study involving two field datasets demonstrated the effectiveness of the developed method. Compared with standalone exponential fitting, the proposed RVM-based model was much better able to predict the remaining useful life of pump impellers. PMID:24051527

  14. Dependence of mycelial morphology on impeller type and agitation intensity.

    PubMed

    Jüsten, P; Paul, G C; Nienow, A W; Thomas, C R

    1996-12-20

    The influence of the agitation conditions on the morphology of Penicillium chrysogenum (freely dispersed and aggregated forms) was examined using radial (Rushton turbines and paddles), axial (pitched blades, propeller, and Prochem Maxflow T), and counterflow impellers (Intermig). Culture broth was taken from a continuous fermentation at steady state and was agitated for 30 min in an ungassed vessel of 1.4-L working volume. The power inputs per unit volume of liquid in the tank, P/V(L), ranged from 0.6 to 6 kW/m(3). Image analysis was used to measure mycelial morphology. To characterize the intensity of the damage caused by different impellers, the mean total hyphal length (freely dispersed form) and the mean projected area (all dispersed types, i.e., also including aggregates) were used. [In this study, breakage of aggregates was taken into account quantitatively for the first time.]At 1.4-L scale and a given P/V(L), changes in the morphology depended significantly on the impeller geometry. However, the morphological data (obtained with different geometries and various P/V(L)) could be correlated on the basis of equal tip speed and two other, less simple, mixing parameters. One is based on the specific energy dissipation rate in the impeller region, which is simply related to P/V(L) and particular impeller geometrical parameters. The other which is developed in this study is based on a combination of the specific energy dissipation rate in the impeller swept volume and the frequency of mycelial circulation through that volume. For convenience, the function arising from this concept is called the "energy dissipation/circulation" function.To test the broader validity of these correlations, scale-up experiments were carried out in mixing tanks of 1.4, 20, and 180 L using a Rushton turbine and broth from a fed-batch fermentation. The energy dissipation/circulation function was a reasonable correlating parameter for hyphal damage over this range of scales, whereas tip speed, P/V(L), and specific energy dissipation rate in the impeller region were poor. Two forms of the energy dissipation/circulation function were considered, one of which additionally allowed for the numbers of vortices behind the blades of each impeller type. Although both forms were successful at correlating the data for the standard impeller designs considered here, there was preliminary evidence that allowing for the vortices would be valuable. (c) 1996 John Wiley & Sons, Inc. PMID:18629946

  15. The effect of gas fraction on centrifugal pump

    NASA Astrophysics Data System (ADS)

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

    2015-01-01

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

  16. [Artificial heart--turbo type blood pump for long-term use].

    PubMed

    Akamatsu, Teruaki

    2003-05-01

    Shortage of donor heart for transplantation necessitates long-term artificial assist heart. Turbo-pump is smaller, simpler and cheaper than the pulsatile displacement type pump, but the turbo-pump has defect of thrombus formation at the shaft seal. Our centrifugal pump with magnetically suspended impellers overcomes this defect and is ready for clinical trials now. The structures and functions are described and are compared with the other newly-developed pump of the same kinds with us. And also the pumps of centrifugal type and axial-type, of which impellers are supported by pivots, are reviewed briefly from the stand point for long-term use. Other pumps are referred too: pumps with hydrodynamic bearing and a pump with the shaft seal which is washed and cooled by saline solution. PMID:12755019

  17. Improved performance in viscous mycelial fermentations by agitator retrofitting.

    PubMed

    Buckland, B C; Gbewonyo, K; Dimasi, D; Hunt, G; Westerfield, G; Nienow, A W

    1988-05-01

    For viscous mycelial fermentations it was demonstrated at the pilot-plant scale that the replacement of standard radial flow Rushton turbines with larger diameter axial-flow Prochem hydrofoil impellers significantly improved oxygen transfer efficiency. It was also determined that the Streptomyces broth under evaluation is highly shear thinning. Separate experiments using a Norcardia broth with similar Theological properties demonstrated that the oxygen transfer coefficient, K(L)a, can be greatly increased by use of water additions to reduce broth viscosity. These observations are consistent with the hypothesis that the improvement in oxygen transfer by changing agitator types is primarily due to an improvement in bulk mixing. A model is presented, based on the concepts of Bajpai and Reuss, which explains this improvement in performance in terms of enlargement of the well mixed micromixer region for viscous mycelial broths. PMID:18584673

  18. Research on design multi-points performance curves of pump

    NASA Astrophysics Data System (ADS)

    Li, L.; Li, H.; Xu, D. H.

    2012-11-01

    The centrifugal pump's performance curves are the most important chart to reveal relevance of different performance parameters. They can show pump's function comprehensively and graphically. However these curves can't be predicted and designed precisely, duo to the complicated flow inside the impeller and the incomplete way to design pump. The complete shape of performance curves can be gained only after test. With the development of industry, many applications need the pump operating well at different flow conditions. It means the pump's performance curves should pass some specific points. This is a problem to the designer who still uses the traditional way to design pumps. In this paper, the Design of experiments was applied to arrange a plan of experiments. Because the theory equations of performance curves contain many geometry factors of impeller, changing these factors have different influence on the shape of curves, the relationship between geometry factors and the performance under different operation points been attained after using variance analysis to deal with experiment data. The relevant regression models and graphs were drawn to help understand these relationships. Depending on the predicted values of geometry factors pump's impeller was redesigned, and the pump's performance been simulated for saving time and cost. Test shows that the shape of performance curves satisfy design objective, this example can be taken as a reference of pump's specific designs.

  19. SSME HPOTP impeller backcavity CFD analysis

    Microsoft Academic Search

    W. W. Hsu; S. J. Lin

    1992-01-01

    The ball bearings behind the Space Shuttle Main Engine (SSME) HPOTP preburner pump have a history of premature wear requiring their replacement. Extensive tests have been conducted in an attempt to identify the operating factors that contribute to the wear. It has been conjectured that the coolant inflow velocity swirl pattern can aid bearing operation by matching ball orbit speed

  20. Computer code for analysing three-dimensional viscous flows in impeller passages and other duct geometries

    NASA Technical Reports Server (NTRS)

    Tatchell, D. G.

    1979-01-01

    A code, CATHY3/M, was prepared and demonstrated by application to a sample case. The preparation is reviewed, a summary of the capabilities and main features of the code is given, and the sample case results are discussed. Recommendations for future use and development of the code are provided.

  1. Estimation of changes in dynamic hydraulic force in a magnetically suspended centrifugal blood pump with transient computational fluid dynamics analysis.

    PubMed

    Masuzawa, Toru; Ohta, Akiko; Tanaka, Nobuatu; Qian, Yi; Tsukiya, Tomonori

    2009-01-01

    The effect of the hydraulic force on magnetically levitated (maglev) pumps should be studied carefully to improve the suspension performance and the reliability of the pumps. A maglev centrifugal pump, developed at Ibaraki University, was modeled with 926 376 hexahedral elements for computational fluid dynamics (CFD) analyses. The pump has a fully open six-vane impeller with a diameter of 72.5 mm. A self-bearing motor suspends the impeller in the radial direction. The maximum pressure head and flow rate were 250 mmHg and 14 l/min, respectively. First, a steady-state analysis was performed using commercial code STAR-CD to confirm the model's suitability by comparing the results with the real pump performance. Second, transient analysis was performed to estimate the hydraulic force on the levitated impeller. The impeller was rotated in steps of 1 degrees using a sliding mesh. The force around the impeller was integrated at every step. The transient analysis revealed that the direction of the radial force changed dynamically as the vane's position changed relative to the outlet port during one circulation, and the magnitude of this force was about 1 N. The current maglev pump has sufficient performance to counteract this hydraulic force. Transient CFD analysis is not only useful for observing dynamic flow conditions in a centrifugal pump but is also effective for obtaining information about the levitation dynamics of a maglev pump. PMID:19894088

  2. Numerical simulation of impeller-volute interaction in centrifugal compressors

    SciTech Connect

    Hillewaert, K.; Van den Braembussche, R.A. [von Karman Inst. for Fluid Dynamics, St-Genesius-Rode (Belgium)

    1999-07-01

    A numerical procedure to predict the impeller-volute interaction in a single-stage centrifugal compressor is presented. The method couples a three-dimensional unsteady flow calculation in the impeller with a three-dimensional time-averaged flow calculation in the volute through an iterative updating of the boundary conditions on the interface of both calculation domains. The method has been used to calculate the flow in a compressor with an external volute at off-design operation. Computed circumferential variations of flow angles, total temperature, and pressure are shown and compared with measurements. The good agreement between the predictions and measurements confirms the validity of the approach.

  3. Novel forging technology of a magnesium alloy impeller with twisted blades of micro-thickness

    Microsoft Academic Search

    J. H. Lee; S. H. Kang; D. Y. Yang

    2008-01-01

    In this work, a novel forging technology has been developed to produce a magnesium alloy impeller with twisted blades of micro-thickness used in a fuel cell system. Due to the very complicated blades of the impeller, a specially designed split die was adopted for successful forging of the impeller. In this split die-set, the coherence of reinforcement ring and split

  4. Carbon monoxide mass transfer for syngas fermentation in a stirred tank reactor with dual impeller configurations.

    PubMed

    Ungerman, Andrew J; Heindel, Theodore J

    2007-01-01

    This study compares the power demand and gas-liquid volumetric mass transfer coefficient, kLa, in a stirred tank reactor (STR) (T = 0.211 m) using different impeller designs and schemes in a carbon monoxide-water system, which is applicable to synthesis gas (syngas) fermentation. Eleven different impeller schemes were tested over a range of operating conditions typically associated with the "after large cavity" region (ALC) of a Rushton-type turbine (D/T = 0.35). It is found that the dual Rushton-type impeller scheme exhibits the highest volumetric mass transfer rates for all operating conditions; however, it also displays the lowest mass transfer performance (defined as the volumetric mass transfer coefficient per unit power input) for all conditions due to its high power consumption. Dual impeller schemes with an axial flow impeller as the top impeller show improved mass transfer rates without dramatic increases in power draw. At high gas flow rates, dual impeller schemes with a lower concave impeller have kLa values similar to those of the Rushton-type dual impeller schemes but show improved mass transfer performance. It is believed that the mass transfer performance can be further enhanced for the bottom concave impeller schemes by operating at conditions beyond the ALC region defined for Rushton-type impellers because the concave impeller can handle higher gas flow rates prior to flooding. PMID:17326659

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

    NASA Astrophysics Data System (ADS)

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

    2015-01-01

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

  6. A Method to Determine the Slip Factor of Centrifugal Pumps through Experiment

    NASA Astrophysics Data System (ADS)

    Zhang, Yu-Liang; Zhu, Zu-Chao; Dou, Hua-Shu; Cui, Bao-Ling; Li, Yi; Xiao, Jun-Jian

    2015-04-01

    In this paper, a method to determine the slip factor of centrifugal impellers is proposed based on the experimental result of the external performance of centrifugal pumps. This proposed method is superior to the conventional experimental method, which needs not to measure the flow parameters at impeller outlet. The results show that the present method can be used to obtain the slip factor at offdesign condition in a wide range of flow rate besides at the design point.

  7. SSME Investment in Turbomachinery Inducer Impeller Design Tools and Methodology

    NASA Technical Reports Server (NTRS)

    Zoladz, Thomas; Mitchell, William; Lunde, Kevin

    2010-01-01

    Within the rocket engine industry, SSME turbomachines are the de facto standards of success with regard to meeting aggressive performance requirements under challenging operational environments. Over the Shuttle era, SSME has invested heavily in our national inducer impeller design infrastructure. While both low and high pressure turbopump failures/anomaly resolution efforts spurred some of these investments, the SSME program was a major benefactor of key areas of turbomachinery inducer-impeller research outside of flight manifest pressures. Over the past several decades, key turbopump internal environments have been interrogated via highly instrumented hot-fire and cold-flow testing. Likewise, SSME has sponsored the advancement of time accurate and cavitating inducer impeller computation fluid dynamics (CFD) tools. These investments together have led to a better understanding of the complex internal flow fields within aggressive high performing inducers and impellers. New design tools and methodologies have evolved which intend to provide confident blade designs which strike an appropriate balance between performance and self induced load management.

  8. HYDRODYNAMICS OF UNBAFFLED VESSELS STIRRED WITH ECCENTRICAL IMPELLERS

    Microsoft Academic Search

    G. Montante; A. Bakker; A. Paglianti; F. Magelli

    So far, most of the computations aimed at providing detailed predictions of the flow field of mechanically stirred vessels have regarded baffled tanks, while less effort has been devoted to unconventional stirred vessels. Unbaffled vessel with eccentrical impeller can be adopted as an alternative to baffled vessels as this configuration is less prone to superficial vortexing: examples of application can

  9. Rotating Instability of a Centrifugal Compressor with 2Dimensional Impeller

    Microsoft Academic Search

    Kyung Jun Kang; You Hwan Shin; Kwang Ho Kim

    2010-01-01

    This study investigated on details of flow characteristics of a compressor with 2-dimensional impeller at various flow rates. Experiment for a low speed compressor model in a water reservoir was performed to analyze the flow field in the vaneless diffuser and volute casing, which was done by PIV measurement. It was also focused on the periodic flow patterns occurring at

  10. INTELLIGENT PERFORMANCE CFD OPTIMISATION OF A CENTRIFUGAL IMPELLER

    Microsoft Academic Search

    Simone Pazzi; Francesco Martelli; Vittorio Michelassi; Marco Giachi; Frank Van den Berghen; Hugues Bersini

    A typical centrifugal impeller characterised by a low flow coefficient and cylindrical blades is optimised by means of an intelligent automatic search program. The procedure consists of a Feasible Sequential Quadratic Programming (FSQP) algorithm (6) coupled to a Lazy Learning (LL) interpolator (1) to speed-up the process. The program is able to handle geometrical constraints to reduce the computational effort

  11. Solid dispersion in the slurry reactor with multiple impellers

    Microsoft Academic Search

    O. P. Klenov; A. S. Noskov

    A whole series of significant catalytic processes are carried out in a slurry reactor with multiple impellers. The selective hydrogenation of sunflower seed oil is the characteristic example of such a process. The liquid phase is the main medium into stirred tank and an investigation of a fluid dynamics of one just as transient regime of solid distribution in liquid

  12. Field Investigation of Cavitation and Flow Induced Vibrations in Submerged Vertical Pumps in a Power Plant

    Microsoft Academic Search

    Tan Chek Zin; M. Salman Leong; Lee Yuk Choi

    Pumping sets are common but often critical operating assets in the industry. Such pumps often do not have adequate pressure\\u000a and flow instrumentation that could detect abnormal hydraulic operating conditions. This paper presents field investigations\\u000a of two submerged vertical pumps with suspected cavitation and flow induced vibrations in a power plant. These pumps had a\\u000a history of catastrophic impeller failures.

  13. Pump station for radioactive waste water

    DOEpatents

    Whitton, John P.; Klos, Dean M.; Carrara, Danny T.; Minno, John J.

    2003-11-18

    A pump station for transferring radioactive particle containing waste water, includes: (a.) an enclosed sump having a vertically elongated right frusto conical wall surface and a bottom surface and (b.) a submersible volute centrifugal pump having a horizontally rotating impeller and a volute exterior surface. The sump interior surface, the bottom surface and the volute exterior surface are made of stainless steel having a 30 Ra or finer surface finish. A 15 Ra finish has been found to be most cost effective. The pump station is used for transferring waste water, without accumulation of radioactive fines.

  14. Canned pump having a high inertia flywheel

    DOEpatents

    Veronesi, L.; Raimondi, A.A.

    1989-12-12

    A canned pump is described which includes a motor, impeller, shaft, and high inertia flywheel mounted within a hermetically sealed casing. The flywheel comprises a heavy metal disk made preferably of a uranium alloy with a stainless steel shell sealably enclosing the heavy metal. The outside surfaces of the stainless steel comprise thrust runners and a journal for mating with, respectively, thrust bearing shoes and radial bearing segments. The bearings prevent vibration of the pump and, simultaneously, minimize power losses normally associated with the flywheel resulting from frictionally pumping surrounding fluid. 5 figs.

  15. Canned pump having a high inertia flywheel

    DOEpatents

    Veronesi, Luciano (O'Hara Twp., Allegheny County, PA); Raimondi, ALbert A. (Monroeville Borough, Allegheny County, PA)

    1989-01-01

    A canned pump is described which includes a motor, impeller, shaft, and high inertia flywheel mounted within a hermetically sealed casing. The flywheel comprises a heavy metal disk made preferably of a uranium alloy with a stainless steel shell sealably enclosing the heavy metal. The outside surfaces of the stainless steel comprise thrust runners and a journal for mating with, respectively, thrust bearing shoes and radial bearing segments. The bearings prevent vibration of the pump and, simultaneously, minimize power losses normally associated with the flywheel resulting from frictionally pumping surrounding fluid.

  16. Experimental study on hemolysis in centrifugal blood pumps: improvement of flow visualization method.

    PubMed

    Ahmed, S; Funakubo, A; Sakuma, I; Fukui, Y; Dohi, T

    1999-06-01

    To evaluate rotary blood pumps, flow visualization is commonly applied to determine the flow patterns in a centrifugal blood pump, which have a relationship to its hemolytic performance. However, it is very troublesome to visualize the flow near the vanes due to the high rotational speed of the impeller. The rotational speed of the impeller in a centrifugal blood pump is usually several hundred revolutions per minute. In this study, we combined a high-speed video camera based imaging method and an optical system in which the image of the rotating impeller was kept stationary. In the optical system, a prism rotating at half the speed of the impeller reflected the image of the impeller. The resultant reflected image was observed by a high-speed video camera through a half mirror. With this optical setup, the image through the half mirror became stationary, and the path of a specific tracer particle could be traced for a longer duration. A longer duration of measurements and better quality of the obtained images were realized through this improvement. Movement of a specific tracer from the inlet portion to the outlet portion of the impeller could be examined using the developed method. PMID:10392282

  17. Technical requirements and limitations of miniaturized axial flow pumps for circulatory support.

    PubMed

    Reul, H

    1994-01-01

    The engineering principles of rotary blood pumps are elucidated by means of a basic introduction into turbomachinery. Additionally, some important dimensionless quantities which relate to pumping characteristics and pump type are introduced. These theoretical fundamentals are applied to the design of high-speed microaxial pumps, especially the two Hemopump versions. The theoretical estimates clearly show that each pump version has its physical limits, especially at small impeller sizes. It is also demonstrated that not any clinically desirable working point of an axial pump can be achieved with an arbitrarily small pump size. PMID:8205568

  18. Parametric performance evaluation of a hydraulic centrifugal pump

    NASA Astrophysics Data System (ADS)

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

    2014-03-01

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

  19. Viscous Buckle Folding

    NSDL National Science Digital Library

    Phil Resor

    In order to better understand ductile deformation and the growth of folds students perform a series of experiments with readily available viscous analog materials. Students begin by exploring the concept of viscosity and viscous flow problems by using Stoke's Law to measure viscosity of corn syrup from the terminal velocity of a falling steel ball. The students then complete a second series of experiments folding a stiffer material (fruit leather) within a corn syrup matrix. By varying the thickness of the fruit leather layer they discover the linear relationship between layer thickness and dominant wavelength predicted by viscous fold theory.

  20. Design and Fabrication of a Vertical Pump Multiphase Flow Loop 

    E-print Network

    Kirkland, Klayton 1965-

    2012-08-24

    , Emanual Marsis, Ramy Moaness, Nicolas Carvajal, and Joseph Marchetti. All of you have contributed enormously to this thesis. Finally, thanks to Karen Vierow for her unwavering support and love. vi NOMENCLATURE GVF Gas Volume Fraction MVP Multi... challenge for centrifugal pumps as the gas tends to accumulate on the low pressure side of the impeller vanes, impeding the flow. For fluids 3 with an appreciable Gas Volume Fraction (GVF), a gas separator can be fitted to the pump ahead...

  1. Effect of blade outlet angle on radial thrust of single-blade centrifugal pump

    NASA Astrophysics Data System (ADS)

    Nishi, Y.; Fukutomi, J.; Fujiwara, R.

    2012-11-01

    Single-blade centrifugal pumps are widely used as sewage pumps. However, a large radial thrust acts on a single blade during pump operation because of the geometrical axial asymmetry of the impeller. This radial thrust causes vibrations of the pump shaft, reducing the service life of bearings and shaft seal devices. Therefore, to ensure pump reliability, it is necessary to quantitatively understand the radial thrust and clarify the behavior and generation mechanism. This study investigated the radial thrust acting on two kinds of single-blade centrifugal impellers having different blade outlet angles by experiments and computational fluid dynamics (CFD) analysis. Furthermore, the radial thrust was modeled by a combination of three components, inertia, momentum, and pressure, by applying an unsteady conservation of momentum to this impeller. As a result, the effects of the blade outlet angle on both the radial thrust and the modeled components were clarified. The total head of the impeller with a blade outlet angle of 16 degrees increases more than the impeller with a blade outlet angle of 8 degrees at a large flow rate. In this case, since the static pressure of the circumference of the impeller increases uniformly, the time-averaged value of the radial thrust of both impellers does not change at every flow rate. On the other hand, since the impeller blade loading becomes large, the fluctuation component of the radial thrust of the impeller with the blade outlet angle of 16 degrees increases. If the blade outlet angle increases, the fluctuation component of the inertia component will increase, but the time-averaged value of the inertia component is located near the origin despite changes in the flow rate. The fluctuation component of the momentum component becomes large at all flow rates. Furthermore, although the time-averaged value of the pressure component is almost constant, the fluctuation component of the pressure component becomes large at a large flow rate. In addition to the increase of the fluctuation component of this pressure component, because the fluctuation component of the inertia and momentum components becomes large (as mentioned above), the radial thrust increases at a large flow rate, as is the case for the impeller with a large blade outlet angle.

  2. Numerical Research on Flow Characteristics of Vortex Stage in Dry High Vacuum Pump

    NASA Astrophysics Data System (ADS)

    Liu, Kun; Gu, Xiao-guang; Ba, De-chun; Li, Pei-yin; Du, Guang-yu; Yue, Xiang-ji; Yang, Naiheng

    With the development of dry high vacuum pump, researches of pumping mechanism of vortex-stage are greatly concerned. This paper presents a horizontal dry high vacuum pump and establishes a numerical model of vortex stage. And then numerical simulation of flow is carried out with FLUENT software. Moreover, it studies how flow regions work on the internal flow and work performance of the vortex stage under various conditions, such as different number of blades and impeller with different blade rake. As a result, numerical simulation shows that there is a large impact on the pumping for different numbers of blades distributed on the impeller, the number of blades of single impeller should be obtained by combining with practical design sizes. In fact, this paper selects the best number of blades as forty-three by calculating and optimizing. In the mean time, there are three cases for the blade rake: pitched vanes, radial vanes and retroverted vanes. For each case, there are both longitudinal vortex and radial vortex existing in the impeller. Considering comprehensively, impeller with radial vanes is selected in the design after simulation and comparisons.

  3. Influence of low-specific speed pump modifications on stability of Y-Q curve

    NASA Astrophysics Data System (ADS)

    Klas, Roman; Pochylý, František; Rudolf, Pavel

    2015-05-01

    Contribution is focused on modification of low-specific speed pump impellers with respect to stability of their Y-Q curves (i.e. head curves). The design modifications are driven by analysis of the dissipated power. First, dissipated power is evaluated by CFD software in individual working parts of the pump and then its dependence on flow rate is investigated. Pressure fields within the pump are also carefully examined. Special attention is paid to impellers and configuration of the blade channels and recirculating channels. Results point to significant influence of the proper inflow to recirculating channels and also to role of the volute, which is more pronounced than in conventional impellers. All integral characteristics from CFD simulations are verified experimentally.

  4. Investigation of flow in centrifugal impeller with tandem inducer 

    E-print Network

    Nishida, Akira

    1976-01-01

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

  5. Advanced direct-design procedure for centrifugal impellers

    NASA Astrophysics Data System (ADS)

    Al-Zubaidy, Sarum N. J.

    1993-02-01

    The design of centrifugal impellers usually starts with a preliminary design making use of one-dimensional flow analysis thus enabling the skeletal dimensions of the impeller to be determined. This is followed by a detailed design that requires the complete description of the three-dimensional geometry which is subsequently modified by means of successive aerodynamic analysis (indirect approach). The initial description of the blade geometry relies heavily on the experience and the engineering judgement of the designer. This article will present a method that will replace this arbitrary stage of the design sequence by a design procedure that will effectively generate the three-dimensional coordinate of impellers designed for a prescribed velocity schedule (direct-design approach). The study suggests that the degree of blade wrapping could - and was controlled by - adjusting the magnitude and the distribution characteristics of the relative pressure loading parameter. The leaning of the mean streamline forward is caused by increasing the loading distribution while a background lean is achieved by decreasing the blade loading. The rate at which the radial relative velocity accelerates was used to eliminate undesirable blade curvatures during the design procedure.

  6. Viscous fluid sheets

    E-print Network

    Savva, Nikos

    2007-01-01

    We present a general theory for the dynamics of thin viscous sheets. Employing concepts from differential geometry and tensor calculus we derive the governing equations in terms of a coordinate system that moves with the ...

  7. Viscous flows, part 1

    NASA Astrophysics Data System (ADS)

    Reddy, J. N.; Ecer, A.

    1987-05-01

    Finite element calculation methods and their application to turbomachinery flows are presented. The governing equations, turbulent flows, incompressible viscous flows, computational schemes, and the penalty function method are covered.

  8. Integrable viscous conservation laws

    NASA Astrophysics Data System (ADS)

    Arsie, Alessandro; Lorenzoni, Paolo; Moro, Antonio

    2015-06-01

    We propose an extension of the Dubrovin–Zhang perturbative approach to the study of normal forms for non-Hamiltonian integrable scalar conservation laws. The explicit computation of the first few corrections leads to the conjecture that such normal forms are parameterized by one single functional parameter, named the viscous central invariant. A constant valued viscous central invariant corresponds to the well-known Burgers hierarchy. The case of a linear viscous central invariant provides a viscous analog of the Camassa–Holm equation, that formerly appeared as a reduction of two-component Hamiltonian integrable systems. We write explicitly the negative and positive hierarchy associated with this equation and prove the integrability showing that they can be mapped respectively into the heat hierarchy and its negative counterpart, named the Klein–Gordon hierarchy. A local well-posedness theorem for periodic initial data is also proven. We show how transport equations can be used to effectively construct asymptotic solutions via an extension of the quasi-Miura map that preserves the initial datum. The method is alternative to the method of the string equation for Hamiltonian conservation laws and naturally extends to the viscous case. Using these tools we derive the viscous analog of the Painlevé I2 equation that describes the universal behaviour of the solution at the critical point of gradient catastrophe.

  9. Backswept impeller and vane island diffuser and shroud for NASA advanced-concepts compressor test rig

    NASA Technical Reports Server (NTRS)

    Perrone, G. L.; Holbrook, M. R.; Mcvaugh, J. M.

    1973-01-01

    A centrifugal impeller based on an existing backswept design was defined. In addition, a vaned diffuser was designed to match this impeller and also to be compatible with an existing 6:1 compressor test rig. The mechanical integrity of this design was verified by analysis. Hardware was procured and inspected to insure conformity with design tolerances. An overspeed test was successfully conducted on one of the impellers fabricated under this program.

  10. Electrostatic charge generation during impeller mixing in two-phase systems 

    E-print Network

    Hernandez, Andrew

    1988-01-01

    for Impeller Mixing for No Water Addition 12 14 15 20 33 Charging Current Dependence on Conductivity for Impeller Mixing for 1% Water Addition . . . 34 Charging Current Dependence on Conductivity for Impeller Mixing for 3% Water Addition . . . 35 10..., and implementation of many industrial operations. In order for electrostatic energies to effect ignition, four conditions must be satisfied(1): 1. Charge must be generated. 2. Charge must accumulate and build up to an ade- quate potential. 3. A discharge...

  11. Concrete volute pumps: technology review and improvement

    NASA Astrophysics Data System (ADS)

    Prunières, R.; Longatte, F.; Catelan, F. X.; Philippot, J. M.

    2012-11-01

    When pumps need to deliver large water flow rates (typically more than 5 m3.s-1), concrete volute pumps (CVP) offer an interesting alternative to standard vertical wet-pit pumps. One of the major advantages of CVP is its simplicity in terms of design, manufacturability and maintainability. In addition, CVP geometrical arrangement allows to reach high performances in terms of hydraulic and mechanical behaviour. These advantages can be specifically appreciated when such pumps are used in the energy field for Power Plants which need high flow rate and reliability, and can lead to important financial savings over the Plant lifetime compared to vertical wet-pit pumps. Finally, as CVP was for a long time limited to total head rise lower than 30 mWC, it was established through CFD analysis that the addition of guide vanes between the impeller and the volute allows to achieve higher head rise without risk.

  12. Study on the performance deterioration of mixed flow impeller due to change in tip clearance

    NASA Astrophysics Data System (ADS)

    Ramesh Rajakumar, D.; Ramamurthy, S.; Govardhan, M.

    2013-12-01

    Performance of mixed flow compressor with un-shrouded impeller strongly depends upon unsteady, asymmetrical flow fields in the axial directions. The flow through the mixed flow impeller is complex due to three-dimensional nature of geometry. In mixed flow impeller, there are clearances between the rotating impeller blades and the casing as the high pressure ratio compressors are usually open shrouded impellers. As a result, certain amount of reduction in the performance is unavoidable due to clearance flows. In the present investigations, numerical analysis is performed using a commercial code to investigate tip clearance effects on through flow. The performance of mixed flow impeller with four different clearances between impeller and stationary shroud are evaluated and compared with experimental results. The impeller performance map was obtained for different operating speeds and mass flow rates with different tip clearances. The result shows that the tip leakage flow strongly interacts with mainstream and contributes to total pressure loss and performance reduction. The pressure and performance decrement are approximately linearly proportional to the gap between impeller and stationary shroud. The analysis showed scope for improvement in design of the compressor for better performance in terms of efficiency and operating range.

  13. Optimal Navier-Stokes Design of Compressor Impellers Using Evolutionary Computation

    NASA Astrophysics Data System (ADS)

    Benini, Ernesto

    2003-09-01

    In the design of modern centrifugal compressor impellers, it is fundamental to account for three-dimensional effects and to use an optimization strategy that helps the designer to achieve the required objectives with the presence of constraints. In this paper, a fully three-dimensional optimization method is described that combines a CFD code and an evolutionary algorithm. The design scenario contemplated here involves the maximization of impeller peak efficiency with constraints on the impeller pressure ratio and operating range. The method is used to improve the performances of a baseline impeller of known characteristics. An optimal solution is proposed and compared to the original configuration.

  14. Hydrogen test of a small, low specific speed centrifugal pump stage

    NASA Technical Reports Server (NTRS)

    1991-01-01

    A small, low specific speed centrifugal pump stage with a 2 inch tip diameter, .030 inch tip width shrouded impeller and volute collector was tested with liquid hydrogen as the pumped fluid. The hydrodynamic design of the pump stage is summarized and the noncavitating and cavitating performance results are presented. Test speeds were 60 and 80 percent of the 77,000 rpm design speed. Liquid hydrogen test results are compared with data from previous tests of the stage in water.

  15. Screw-type pump for coal feeding

    SciTech Connect

    Hilbert, J.D. Jr.

    1983-05-01

    This article describes the Type-M pumps system, which provides the reliable and accurate coal feeding needed for the success of fluidized-bed combustion and other coal-firing requirements. The Type-M pump feed unit provides the safety feature with its internal flapper valve to prevent the possibility of blowback. It features bearing supports at both ends of the screw impeller shaft which permits smooth running and maintenance-free operation under variable feed and light load conditions. It has demonstrated its capability to handle not only finely pulverized coal but also coarse coal as well as a mixture of coarse coal and 1/8 x 0 limestone.

  16. Measurements by laser Doppler velocimetry in the casing/impeller clearance gap of a biocentrifugal ventricular assist device model.

    PubMed

    Chua, Leok Poh; Ong, Kang Shiu; Song, Guoliang; Ji, Wenfa

    2009-04-01

    The velocity distributions in the clearance gap of the Kyoto-NTN biocentrifugal ventricular assist device model were measured by laser Doppler velocimetry (LDV) at three inlet flow conditions, namely operating, fully opened, and fully closed conditions. The results obtained have a similar trend as in the earlier measurements using air as medium and the hot-wire probe, a washout mechanism that is a segment of fluids in the gap situated from theta = 60 degrees to 220 degrees, has a larger radial velocity component flowing toward the eye of the pump, as compared to other regions in the gap where the tangential velocity component is dominant. It is essential to have a good washout for the leakage flow through the clearance gap between the stationary casing and the impeller of the pump so that the blood will not keep on circulating in the gap but is washed out to the eye in order to reduce the chances of being destroyed. Although the detailed velocity distributions are not the same, this should be due to the minor fabrication differences between two pump models. The current noninvasive LDV measurements should have a better representation of the actual flow field than the earlier studies due to the blood analog being used as the flow medium. Furthermore, as compared to the methods used in the earlier studies, there is basically no modification of the pump geometry in the present measurement. PMID:19335413

  17. Experiment of a centrifugal pump during changing speed operation

    NASA Astrophysics Data System (ADS)

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

    2012-11-01

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

  18. Nonconformal viscous anisotropic hydrodynamics

    NASA Astrophysics Data System (ADS)

    Bazow, Dennis; Heinz, Ulrich; Martinez, Mauricio

    2015-06-01

    We generalize the derivation of viscous anisotropic hydrodynamics from kinetic theory to allow for nonzero particle masses. The macroscopic theory is obtained by taking moments of the Boltzmann equation after expanding the distribution function around a spheroidally deformed local momentum distribution whose form has been generalized by the addition of a scalar field that accounts nonperturbatively (i.e., already at leading order) for bulk viscous effects. Hydrodynamic equations for the parameters of the leading-order distribution function and for the residual (next-to-leading order) dissipative flows are obtained from the three lowest moments of the Boltzmann equation. The approach is tested for a system undergoing (0 +1 )-dimensional boost-invariant expansion for which the exact solution of the Boltzmann equation in the relaxation time approximation is known. Nonconformal viscous anisotropic hydrodynamics is shown to approximate this exact solution more accurately than any other known hydrodynamic approximation.

  19. An experimental study on pump clogging

    NASA Astrophysics Data System (ADS)

    Isono, M.; Nohmi, M.; Uchida, H.; Kawai, M.; Kudo, H.; Kawahara, T.; Miyagawa, K.; Saito, S.

    2014-03-01

    For sewage pump that various foreign substance is flowed into, anti-clogging performance is a factor as important as pump efficiency in order to avoid clogging trouble by foreign substance. Many investigations about pump inner flow and pump efficiency estimation have been carried out conventionally in order to realize coexistence with anti-clogging performance and pump performance. And these results have been reflected in construction of the running water section design method. As a index of anti-clogging performance, "impeller passage diameter" which is diameter of spherical solid that can pass through the pump is used widely. And there are various type of the sewage pump which have large impeller passage diameter. However real cause of clog is not a solid, and it is fibrous material such as towel and clothes, vinyl and paper diaper. In most case these material accumulate in the pump, so that clog is occurred. In this study, for the purpose of quantification of anti-clogging performance against fibrous materials, the factor that affect to clogging of pump was investigated by pump model test using a string. The test is done based on Taguchi method. In this test, type of the pump model, diameter of the string, material of the string, length of the string and flow rate are selected for the factor, and the effect that they have on the clogging of the pump was investigated. As a result of this test, it was made clear that length of the string has a strong influence on the clogging of the pump. And from the result of this test, evaluation method of anti-clogging performance of the pump against fibrous material by using string was considered. According to the result of above test based on Taguchi method, it was assumed that quantification of anti-clogging performance against fibrous materials is possible by flowing plural strings into the pump and calculating the probability of passing. Plurality sewage pumps of different types were evaluated based on this assumption. And It was confirmed that it is possible to compare anti clogging performance of the pump against fibrous materials quantitatively. And the specification of the string was selected according to the result of the test based on Taguchi method. By this method, one of the evaluation method on anti-clogging performance against fibrous materials was established.

  20. Numerical Simulation of Tubular Pumping Systems with Different Regulation Methods

    NASA Astrophysics Data System (ADS)

    Zhu, Honggeng; Zhang, Rentian; Deng, Dongsheng; Feng, Xusong; Yao, Linbi

    2010-06-01

    Since the flow in tubular pumping systems is basically along axial direction and passes symmetrically through the impeller, most satisfying the basic hypotheses in the design of impeller and having higher pumping system efficiency in comparison with vertical pumping system, they are being widely applied to low-head pumping engineering. In a pumping station, the fluctuation of water levels in the sump and discharge pool is most common and at most time the pumping system runs under off-design conditions. Hence, the operation of pump has to be flexibly regulated to meet the needs of flow rates, and the selection of regulation method is as important as that of pump to reduce operation cost and achieve economic operation. In this paper, the three dimensional time-averaged Navier-Stokes equations are closed by RNG ?-? turbulent model, and two tubular pumping systems with different regulation methods, equipped with the same pump model but with different designed system structures, are numerically simulated respectively to predict the pumping system performances and analyze the influence of regulation device and help designers make final decision in the selection of design schemes. The computed results indicate that the pumping system with blade-adjusting device needs longer suction box, and the increased hydraulic loss will lower the pumping system efficiency in the order of 1.5%. The pumping system with permanent magnet motor, by means of variable speed regulation, obtains higher system efficiency partly for shorter suction box and partly for different structure design. Nowadays, the varied speed regulation is realized by varied frequency device, the energy consumption of which is about 3˜4% of output power of the motor. Hence, when the efficiency of variable frequency device is considered, the total pumping system efficiency will probably be lower.

  1. Induction in a von Karman flow driven by ferromagnetic impellers Gautier Verhille1

    E-print Network

    Boyer, Edmond

    by the rotation of impellers made of material with varying electrical conductivity and magnetic permeability observed in situations where the fluid is driven by the motion of soft iron impellers. When replaced by non-magnetic. Gallium is the working fluid and magnetic Reynolds numbers of order unity are achieved. We find

  2. The experimental study of matching between centrifugal compressor impeller and diffuser

    Microsoft Academic Search

    H. Tamaki; H. Nakao; M. Saito

    1999-01-01

    the centrifugal compressor for a marine use turbocharger with its design pressure ratio of 3.2 was tested with a vaneless diffuser and various vaned diffusers. Vaned diffusers were chosen to cover impeller operating range as broad as possible. The analysis of the static pressure ratio in the impeller and the diffusing system, consisting of the diffuser and scroll, showed that

  3. Department of Industrial Engineering Spring 2014 Estimating Tool for Single-Piece Impeller Milling

    E-print Network

    Demirel, Melik C.

    component of centrifugal compressors. Currently, there is no system in place to estimate the cycle time specific tools, tool holders, and machines depending on impeller design - Determine cycle time for a particular design. 2. The program selects appropriate tools for roughing and finishing based on impeller

  4. Design optimization of a mixed-flow compressor impeller for a small turbojet engine

    Microsoft Academic Search

    Mert Cevik; Oguz Uzol

    2011-01-01

    Purpose – This paper aims to present the results of a design optimization study for the impeller of a small mixed-flow compressor. The objective of the optimization is to obtain an impeller geometry that could minimize a cost function based on the specific thrust and the thrust specific fuel consumption of a small turbojet engine. Design\\/methodology\\/approach – The design methodology

  5. Blood Pump Bearing System

    NASA Technical Reports Server (NTRS)

    Aber, Gregory S. (Inventor)

    2000-01-01

    An apparatus is provided for a blood pump bearing system within a pump housing to support long-term highspeed rotation of a rotor with an impeller blade having a plurality of individual magnets disposed thereon to provide a small radial air gap between the magnets and a stator of less than 0.025 inches. The bearing system may be mounted within a flow straightener, diffuser, or other pump element to support the shaft of a pump rotor. The bearing system includes a zirconia shaft having a radiused end. The radiused end has a first radius selected to be about three times greater than the radius of the zirconia shaft. The radiused end of the zirconia shaft engages a flat sapphire endstone. Due to the relative hardness of these materials a flat is quickly produced during break-in on the zirconia radiused end of precisely the size necessary to support thrust loads whereupon wear substantially ceases. Due to the selection of the first radius, the change in shaft end-play during pump break-in is limited to a total desired end-play of less than about 0.010 inches. Radial loads are supported by an olive hole ring jewel that makes near line contact around the circumference of the Ir shaft to support big speed rotation with little friction. The width of olive hole ring jewel is small to allow heat to conduct through to thereby prevent heat build-up in the bearing. A void defined by the bearing elements may fill with blood that then coagulates within the void. The coagulated blood is then conformed to the shape of the bearing surfaces.

  6. Blood Pump Bearing System

    NASA Technical Reports Server (NTRS)

    Aber, Gregory S. (Inventor)

    1999-01-01

    Methods and apparatus are provided for a blood pump bearing system within a pump housing to support long-term high-speed rotation of a rotor with an impeller blade having a plurality of individual magnets disposed thereon to provide a small radial air gap between the magnets and a stator of less than 0.025 inches. The bearing system may be mounted within a flow straightener, diffuser, or other pump element to support the shaft of a pump rotor. The bearing system includes a zirconia shaft having a radiused end. The radiused end has a first radius selected to be about three times greater than the radius of the zirconia shaft. The radiused end of the zirconia shaft engages a flat sapphire endstone. Due to the relative hardness of these materials a flat is quickly produced during break-in on the zirconia radiused end of precisely the size necessary to support thrust loads whereupon wear substantially ceases. Due to the selection of the first radius, the change in shaft end-play during pump break-in is limited to a total desired end-play of less than about 0.010 inches. Radial loads are supported by an olive hole ring jewel that makes near line contact around the circumference of the shaft to support high speed rotation with little friction. The width of olive hole ring jewel is small to allow heat to conduct through to thereby prevent heat build-up in the bearing. A void defined by the bearing elements may fill with blood that then coagulates within the void. The coagulated blood is then conformed to the shape of the bearing surfaces.

  7. Design of a Gas-Liquid Unbaffled Stirred Tank with a Concave Blade Impeller

    NASA Astrophysics Data System (ADS)

    Devi, T. T.; Kumar, Bimlesh

    2015-01-01

    Experimental investigation of unbaffled multiphase (gas-liquid) stirred tanks is conducted with the use of a concave blade impeller to analyze mass transfer, gassed power, and gas holdup. The experiments are carried out with various impeller diameter to tank diameter ratios and impeller clearances. The design criterion for the mass transfer rate is proposed, and its prediction capability is found to be satisfactory. The results show that the gassed power is dependent on the impeller diameter to tank diameter ratio and impeller clearance. The design criteria for gassed power to ungassed power ratio and gas holdup are also introduced. Multiphase modeling is done by employing the computational fluid dynamics (CFD) techniques to observe the characteristic flow pattern transition and to carry out a qualitative analysis of the mass transfer rate.

  8. Viscous Hydraulic Jumps Submitted by

    E-print Network

    Bush, John W.M.

    Viscous Hydraulic Jumps Submitted by Jeffrey M. Aristoff, Jeffrey D. Leblanc, Annette E. Hosoi, and John W. M. Bush, Massachusetts Institute of Technology We examine the form of the viscous hydraulic of height 2­10 mm. Elegaard et al.1 first demonstrated that the axial symme- try of the viscous hydraulic

  9. Influence of impeller shroud forces on turbopump rotor dynamics

    NASA Technical Reports Server (NTRS)

    Williams, J. P.; Childs, Dara W.

    1993-01-01

    The shrouded-impeller leakage path forces calculated by Childs have been analyzed to answer two questions. First, because of certain characteristics or the results of Childs, the forces could not be modeled with traditional approaches. Therefore, an approach has been devised to include the forces in conventional rotordynamic analyses. The forces were found to be well-modeled with this approach. Finally, the effect these forces had on a simple rotor-bearing system was analyzed, and, therefore, they, in addition to seal forces, were applied to a Jeffcott rotor. The traditional methods of dynamic system analysis were modified to incorporate the impeller forces and yielded results for the eigenproblem, frequency response, critical speed, transient response, and an iterative technique for finding the frequency of free vibration as well as system stability. All results lead to the conclusion that the forces have little influence on natural frequency but can have appreciable effects on system stability. Specifically, at higher values of fluid swirl at the leakage path entrance, relative stability is reduced. The only unexpected response characteristics that occurred are attributed to the nonlinearity of the model.

  10. Investigation of the hydraulic design for a high-performance centrifugal pump

    NASA Astrophysics Data System (ADS)

    Nagahara, T.; Okihara, T.; Torii, D.

    2012-11-01

    We investigated the hydraulic design in terms of high efficiency and good cavitation performance of centrifugal pumps for water supplies. The subject of the investigation was the centrifugal pump, which consists of a suction bend, impeller, diffuser, and discharge volute. The investigation was basically conducted using computational fluid dynamics (CFD) with design of experiments (DOE) and an optimization technique. The suction bend design was implemented first to obtain a uniform flow at the impeller inlet to provide good cavitation performance. We investigated the sensitivity of each parameter value comprising the suction bend configuration for obtaining uniform flow using a parameter design technique with DOE and CFD analyses. The key parameters that enable a better flow field were estimated efficiently and the values of the parameters were adjusted to obtain the optimized configuration. On the other hand, to achieve high performance of the impeller and diffuser shape, the effect of the configuration parameter values on hydraulic loss was also examined using the parameter design based on CFD and a multi-objective optimization technique. The investigation for obtaining a shape achieving high hydraulic efficiency was made practical by taking into account the trade-off of performance characteristics, i.e., performance instability at a low flow rate and gradient of the head curve. When predicting hydraulic performance, it is important to investigate the interaction of flow between the impeller and diffuser to accurately simulate the flow field. The combined analysis of the impeller and diffuser, therefore, was implemented using unsteady flow simulation, and the results were applied to the parameter design using an optimization technique. Finally, the unsteady flow calculation of a complete pump was carried out to confirm the appropriateness of the hydraulic design. The hydraulic performance of the pump was also confirmed using a model pump test. As the result of these investigations, the hydraulic shape of a high-efficiency and high-cavitation centrifugal pump was developed.

  11. Optimization of a continuous hybrid impeller mixer via computational fluid dynamics.

    PubMed

    Othman, N; Kamarudin, S K; Takriff, M S; Rosli, M I; Engku Chik, E M F; Meor Adnan, M A K

    2014-01-01

    This paper presents the preliminary steps required for conducting experiments to obtain the optimal operating conditions of a hybrid impeller mixer and to determine the residence time distribution (RTD) using computational fluid dynamics (CFD). In this paper, impeller speed and clearance parameters are examined. The hybrid impeller mixer consists of a single Rushton turbine mounted above a single pitched blade turbine (PBT). Four impeller speeds, 50, 100, 150, and 200 rpm, and four impeller clearances, 25, 50, 75, and 100 mm, were the operation variables used in this study. CFD was utilized to initially screen the parameter ranges to reduce the number of actual experiments needed. Afterward, the residence time distribution (RTD) was determined using the respective parameters. Finally, the Fluent-predicted RTD and the experimentally measured RTD were compared. The CFD investigations revealed that an impeller speed of 50 rpm and an impeller clearance of 25 mm were not viable for experimental investigations and were thus eliminated from further analyses. The determination of RTD using a k-? turbulence model was performed using CFD techniques. The multiple reference frame (MRF) was implemented and a steady state was initially achieved followed by a transient condition for RTD determination. PMID:25170524

  12. Optimization of a Continuous Hybrid Impeller Mixer via Computational Fluid Dynamics

    PubMed Central

    Othman, N.; Kamarudin, S. K.; Takriff, M. S.; Rosli, M. I.; Engku Chik, E. M. F.; Meor Adnan, M. A. K.

    2014-01-01

    This paper presents the preliminary steps required for conducting experiments to obtain the optimal operating conditions of a hybrid impeller mixer and to determine the residence time distribution (RTD) using computational fluid dynamics (CFD). In this paper, impeller speed and clearance parameters are examined. The hybrid impeller mixer consists of a single Rushton turbine mounted above a single pitched blade turbine (PBT). Four impeller speeds, 50, 100, 150, and 200 rpm, and four impeller clearances, 25, 50, 75, and 100 mm, were the operation variables used in this study. CFD was utilized to initially screen the parameter ranges to reduce the number of actual experiments needed. Afterward, the residence time distribution (RTD) was determined using the respective parameters. Finally, the Fluent-predicted RTD and the experimentally measured RTD were compared. The CFD investigations revealed that an impeller speed of 50 rpm and an impeller clearance of 25 mm were not viable for experimental investigations and were thus eliminated from further analyses. The determination of RTD using a k-? turbulence model was performed using CFD techniques. The multiple reference frame (MRF) was implemented and a steady state was initially achieved followed by a transient condition for RTD determination. PMID:25170524

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

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

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

  14. Experimental Study of Erosion Wear in a Centrifugal Slurry Pump Using Coriolis Wear Test Rig

    Microsoft Academic Search

    Sunil Chandel; S. N. Singh; V. Seshadri

    2012-01-01

    The erosion wear in slurry pumps has been identified as a major problem during transportation of slurry as it affects the equipment performance and reduces its reliability and operation life. To simulate the erosion mechanism in slurry equipments mainly in casing and impeller, the Coriolis erosion test rig on the lines proposed by Pagalthivarthi and Helmly (1992) has been suitably

  15. Viscous Universe Models

    NASA Astrophysics Data System (ADS)

    Grøn, Øyvind; Darian, Diako

    We give a review of viscous relativistic universe models that have been presented during the period from 1990 until the present time. In particular we discuss the properties of isotropic and homogeneous universe models, and of anisotropic and homogeneous Bianchi type I models. We consider these types of models both in the context of the non-causal Eckhart theory and the causal Israel-Stewart theory.

  16. Rotordynamic forces acting on a centrifugal open impeller in whirling motion by using active magnetic bearing

    NASA Astrophysics Data System (ADS)

    Nagao, N.; Eguchi, M.; Uchiumi, M.; Yoshida, Y.

    2013-03-01

    Rotordynamic forces acting on a centrifugal open impeller of a rocket engine turbopump were measured using a rotordynamic test stand controlled by active magnetic bearings. The tangential rotordynamic force ft had a small constantly negative value in the measured range. The direct stiffness K had a positive value under various test conditions. In general, direct stiffness K of a closed impeller had a negative value because of the Bernoulli effect. In the case of open impellers, the Bernoulli effect is speculated to be smaller because the absence of a front shroud makes K positive.

  17. Application of two turbulence models for computation of cavitating flows in a centrifugal pump

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

    To seek a better numerical method to simulate the cavitating flow field in a centrifugal pump, the applications between RNG k- ? and LES turbulence model were compared by using the Zwart-Gerber-Belamri cavitation model. It was found that both the models give almost the same results with respect to pump performance and cavitation evolutions including growth, local contraction, stability and separation in the impeller passage. But the LES model can not only capture the pump suction recirculation and the low frequency fluctuation caused by it, but also combine the changes of the shaft frequency amplitude acting on the impeller with the cavitation unstable characteristics. Thus the LES model has more advantages than RNG k- ? model in calculating the unsteady cavitating flow in a centrifugal pump.

  18. Decontamination of the reactor coolant pump in Maanshan nuclear power plant

    Microsoft Academic Search

    Iuan-Jou Yang; Mao-Ying Teng; Wu-Ing Huan; Yuan-Lung Sun

    1996-01-01

    To reduce the radiation dose that accumulated on the reactor coolant pump, decontamination work was carried out at the Maanshan Nuclear Power Plant. A four-step alkaline permanganate (AP)-CanDecon process was applied to remove the activity on the turning vane diffuser and pump impeller. The first step consisted of 8 h of AP treatment and 7 h of decontamination. It was

  19. Unsteady flow investigation in rotor-stator interface of a radial diffuser pump

    Microsoft Academic Search

    Jianjun Feng; F. K. Benra; H. J. Dohmen

    2010-01-01

    The flow in a vaned diffuser radial pump is fully turbulent and strongly unsteady, caused by the rotor-stator interaction.\\u000a In this paper, two-dimensional laser Doppler velocimetry (LDV) measurement results have been utilized to investigate the unsteady\\u000a flow in a low specific speed radial diffuser pump with leaning impeller trailing edges. CFD simulations have been also conducted\\u000a to provide more extensive

  20. Cavitation improvement of double suction centrifugal pump HPP Fuhren

    NASA Astrophysics Data System (ADS)

    Škerlavaj, A.; Titzschkau, M.; Pavlin, R.; Vehar, F.; Mežnar, P.; Lipej, A.

    2012-11-01

    A double suction storage pump has been refurbished because of the strong cavitation which resulted in cavitation damage on blade and consequently in frequent repairs of the impeller. The analyses of the old and the new impeller were done by the computational fluid dynamics (CFD), performing transient simulations with the commercial solver Ansys CFX. In the simulations, the scale-adaptive-simulation with the curvature correction (SAS-CC) turbulence model was used. No model tests were carried out. Additionally, observations with the digital camera were made through the specially designed plexi-glass window, mounted at the lid at the suction side. The predicted pump head at the operating point agrees well with the pump characteristics measurements, performed with the direct thermodynamic method. The extent of the cavitation predicted by CFD is smaller than the observed one because the cloud cavitation was not predicted. The observations of the cavitation extent show that the impeller design is better than the old one, which was also possible to anticipate based on the CFD results.

  1. The role of impeller outflow conditions on the performance and stability of airfoil vaned radial diffusers

    E-print Network

    Everitt, Jonathan (Jonathan Neil)

    2014-01-01

    This thesis quantifies the relative importance of the impeller outflow angle, Mach number, non-uniformity and unsteadiness on diffuser performance, through diffuser experiments in a compressor stage and in a swirling flow ...

  2. Method of analysis for compressible flow through mixed-flow centrifugal impellers of arbitrary design

    NASA Technical Reports Server (NTRS)

    Hamrick, Joseph T; Ginsburg, Ambrose; Osborn, Walter M

    1952-01-01

    A method is presented for analysis of the compressible flow between the hub and the shroud of mixed-flow impellers of arbitrary design. Axial symmetry was assumed, but the forces in the meridional (hub to shroud) plane, which are derived from tangential pressure gradients, were taken into account. The method was applied to an experimental mixed-flow impeller. The analysis of the flow in the meridional plane of the impeller showed that the rotational forces, the blade curvature, and the hub-shroud profile can introduce severe velocity gradients along the hub and the shroud surfaces. Choked flow at the impeller inlet as determined by the analysis was verified by experimental results.

  3. Effects of curvature and rotation on turbulence in the NASA low-speed centrifugal compressor impeller

    NASA Astrophysics Data System (ADS)

    Moore, Joan G.; Moore, John

    1992-07-01

    The flow in the NASA Low-Speed Impeller is affected by both curvature and rotation. The flow curves due to the following: (1) geometric curvature, e.g. the curvature of the hub and shroud profiles in the meridional plane and the curvature of the backswept impeller blades; and (2) secondary flow vortices, e.g. the tip leakage vortex. Changes in the turbulence and effective turbulent viscosity in the impeller are investigated. The effects of these changes on three-dimensional flow development are discussed. Two predictions of the flow in the impeller, one with, and one without modification to the turbulent viscosity due to rotation and curvature, are compared. Some experimental and theoretical background for the modified mixing length model of turbulent viscosity will also be presented.

  4. Effects of curvature and rotation on turbulence in the NASA low-speed centrifugal compressor impeller

    NASA Technical Reports Server (NTRS)

    Moore, Joan G.; Moore, John

    1992-01-01

    The flow in the NASA Low-Speed Impeller is affected by both curvature and rotation. The flow curves due to the following: (1) geometric curvature, e.g. the curvature of the hub and shroud profiles in the meridional plane and the curvature of the backswept impeller blades; and (2) secondary flow vortices, e.g. the tip leakage vortex. Changes in the turbulence and effective turbulent viscosity in the impeller are investigated. The effects of these changes on three-dimensional flow development are discussed. Two predictions of the flow in the impeller, one with, and one without modification to the turbulent viscosity due to rotation and curvature, are compared. Some experimental and theoretical background for the modified mixing length model of turbulent viscosity will also be presented.

  5. The Effect of Impeller Type on Floc Size and Structure during Shear-Induced Flocculation

    PubMed

    Spicer; Keller; Pratsinis

    1996-12-01

    The effect of impeller type and shear rate on the evolution of floc size and structure during shear-induced flocculation of polystyrene particles with aluminum sulfate is investigated by image analysis. One radial flow (six-blade Rushton turbine) and two axial flow (three-blade fluid foil, four-blade 45° pitch) impeller configurations are examined. The steady state average floc size is shown to depend on the frequency of recirculation to the impeller zone and its characteristic velocity gradient. The concepts of fractal geometry are used to characterize the floc structure. For all impellers, the two-dimensional floc fractal dimension, Dpf, increases during floc growth, indicating formation of more open structures. Later on, Dpf levels off at a steady state value as breakage becomes significant and the floc size distribution approaches steady state. The shear rate does not affect the steady state Dpf of the flocs within experimental uncertainty. PMID:8954644

  6. Characterization of unsteady loading due to impeller-diffuser interaction in centrifugal compressors

    E-print Network

    Lusardi, Christopher (Christopher Dean)

    2012-01-01

    Time dependent simulations are used to characterize the unsteady impeller blade loading due to imipeller-diffuser interaction in centrifugal compressor stages. The capability of simulations are assessed by comparing results ...

  7. Unsteady flow at the outlet of the high specific speed centrifugal compressor impeller

    NASA Astrophysics Data System (ADS)

    Kano, F.; Shirakami, T.

    1984-10-01

    The unsteady flow at the outlet of the high-specific-speed mixed-flow impeller was studied. The flow is strongly influenced by the impeller blading. On the other hand, the flow influences the performance of the stationary vanes downstream of the impeller. The flow path at the outlet of the mixed-flow impeller is inclined to the axial direction and is curved in the meridional plane. The study was carried out to develop the 30 MW centrifugal compressor. This compressor is used in the field of coal gasification, geothermal power generation, etc. The distributions of flow velocity, pressure, and temperature of three-dimensional flow were measured using a high-sensitivity pressure transducer and a total temperature probe. The flow was surveyed across the entire passage at about ten axial locations including the endwall boundary layer. A theoretical analysis was also carried out using the linearized Navier-Stokes equation.

  8. Electrostatic charge generation during impeller mixing in two-phase systems

    E-print Network

    Hernandez, Andrew

    1988-01-01

    ELECTROSTATIC CHARGE GENERATION DURING IMPELLER MIXING IN TWO-PHASE SYSTEMS A Thesis by ANDREW HERNANDEZ, ZR. Submitted to the Graduate College of Texas A&M University in partial fulfillment of the requirements for the degree of MASTER... OF SCIENCE August 1988 Major Subject: Safety Engineering ELECTROSTATIC CHARGE GENERATION DURING IMPELLER MIXING IN TWO-PHASE SYSTEMS A Thesis by ANDREW HERNANDEZ, JR. Approved as to style and content by: John P. Wag hair of Comm ttee) J ome J...

  9. The influence of the meridional impeller shape on the energy-transfer in centrifugal compressors

    Microsoft Academic Search

    K. Bammert; M. Rautenberg; P. Knapp

    1980-01-01

    Three radial flow impellers were tested having an elliptic blade shape and identical blade geometry at inlet and exit but different shapes of the meridional contours. The compressor maps with pressure ratios up to 2.9:1 are compared using time-dependent measurements of the static pressure at the shroud and of the flow angles closely downstream of the impeller. From these measurements,

  10. The vibration behavior of impeller blades in the five-axis CNC flank milling process

    Microsoft Academic Search

    Kawin Sonthipermpoon; E. Bohez; H. Hasemann; M. Rautenberg

    2010-01-01

    Today, in most cases, impellers of centrifugal compressors are produced by flank milling on five-axis CNC milling machines.\\u000a The complex three-dimensional geometry of the very thin blades consists of ruled surfaces. The flank milling process allows\\u000a a fast production of the impellers and the surface of the blades is of high quality. The limited strength of the very thin\\u000a blades

  11. Theoretical analysis of incompressible flow through a radial-inlet centrifugal impeller at various weight flows

    NASA Technical Reports Server (NTRS)

    Kramer, James J; Prian, Vasily D; Wu, Chung-Hua

    1956-01-01

    A method for the solution of the incompressible nonviscous flow through a centrifugal impeller, including the inlet region, is presented. Several numerical solutions are obtained for four weight flows through an impeller at one operating speed. These solutions are refined in the leading-edge region. The results are presented in a series of figures showing streamlines and relative velocity contours. A comparison is made with the results obtained by using a rapid approximate method of analysis.

  12. LDV measurements of a mixed-flow impeller at design and near stall

    Microsoft Academic Search

    John R. Fagan; Sanford Fleeter

    1991-01-01

    A series of experiments are performed to investigate and quantify the design and off-design three-dimensional mean flow in a centrifugal compressor impeller. The experiments entail the acquisition and analysis of LDV data in the impeller passages of a low-speed research mixed-flow compressor operating at its design point and at a point near the inception of rotating stall. The LDV data

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

    NASA Astrophysics Data System (ADS)

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

    2012-11-01

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

  14. Mechanically tunable microlasers based on highly viscous chiral liquid crystals

    NASA Astrophysics Data System (ADS)

    Shibaev, Petr V.; Crooker, Benjamin; Manevich, Michael; Hanelt, Eckhard

    2011-12-01

    Chiral composition is designed for highly viscous lasing microemitters. The composition forms cholesteric liquid crystal and after doping with pyrromethene 597 was used as an active lasing media in stretchable aluminized silicone cavities. Optical pumping of the system led to lasing at the wavelengths defined by a degree of cavity deformation. Lasing thresholds were lower in aluminized cavity than in transparent cavity. A simple model allowing to predict the shift of lasing wavelength as a function of deformation is developed.

  15. DownHole Emulsification for Improving Viscous Crude Production

    Microsoft Academic Search

    R. SIMON; W. G. POYNTER

    1968-01-01

    The downhole emulsification process has been developed to improve productivity and operating efficiency of oil wells that produce viscous crudes. The process involves using surface-active chemicals in the well bore to convert high viscosity oil or water-in-oil (W\\/O) emulsions to low viscosity oil-in-water (O\\/W) emulsions. Improved pump efficiency, faster rod drop rate, and lower flow-line pressure drop result. Benefits obtainable

  16. Dynamics of oscillating viscous droplets immersed in viscous media

    Microsoft Academic Search

    Y. Bayazitoglu; P. V. R. Suryanarayana

    1992-01-01

    Summary Damped oscillations of a viscous droplet immersed in a viscous medium are considered in detail. The characteristic equation is solved numerically for arbitrary, finite fluid properties. The cylinder functions in the characteristic equation are solved using an accurate continued fraction algorithm, and the complex decay factor is searched using a minimization scheme. Oscillation frequency and damping rate results are

  17. Reduced-order modeling for mistuned centrifugal impellers with crack damages

    NASA Astrophysics Data System (ADS)

    Wang, Shuai; Zi, Yanyang; Li, Bing; Zhang, Chunlin; He, Zhengjia

    2014-12-01

    An efficient method for nonlinear vibration analysis of mistuned centrifugal impellers with crack damages is presented. The main objective is to investigate the effects of mistuning and cracks on the vibration features of centrifugal impellers and to explore effective techniques for crack detection. Firstly, in order to reduce the input information needed for component mode synthesis (CMS), the whole model of an impeller is obtained by rotation transformation based on the finite element model of a sector model. Then, a hybrid-interface method of CMS is employed to generate a reduced-order model (ROM) for the cracked impeller. The degrees of freedom on the crack surfaces are retained in the ROM to simulate the crack breathing effects. A novel approach for computing the inversion of large sparse matrix is proposed to save memory space during model order reduction by partitioning the matrix into many smaller blocks. Moreover, to investigate the effects of mistuning and cracks on the resonant frequencies, the bilinear frequency approximation is used to estimate the resonant frequencies of the mistuned impeller with a crack. Additionally, statistical analysis is performed using the Monte Carlo simulation to study the statistical characteristics of the resonant frequencies versus crack length at different mistuning levels. The results show that the most significant effect of mistuning and cracks on the vibration response is the shift and split of the two resonant frequencies with the same nodal diameters. Finally, potential quantitative indicators for detection of crack of centrifugal impellers are discussed.

  18. Use of CFD Analyses to Predict Disk Friction Loss of Centrifugal Compressor Impellers

    NASA Astrophysics Data System (ADS)

    Cho, Leesang; Lee, Seawook; Cho, Jinsoo

    To improve the total efficiency of centrifugal compressors, it is necessary to reduce disk friction loss, which is expressed as the power loss. In this study, to reduce the disk friction loss due to the effect of axial clearance and surface roughness is analyzed and methods to reduce disk friction loss are proposed. The rotating reference frame technique using a commercial CFD tool (FLUENT) is used for steady-state analysis of the centrifugal compressor. Numerical results of the CFD analysis are compared with theoretical results using established experimental empirical equations. The disk friction loss of the impeller is decreased in line with increments in axial clearance until the axial clearance between the impeller disk and the casing is smaller than the boundary layer thickness. In addition, the disk friction loss of the impeller is increased in line with the increments in surface roughness in a similar pattern as that of existing experimental empirical formulas. The disk friction loss of the impeller is more affected by the surface roughness than the change of the axial clearance. To minimize disk friction loss on the centrifugal compressor impeller, the axial clearance and the theoretical boundary layer thickness should be designed to be the same. The design of the impeller requires careful consideration in order to optimize axial clearance and minimize surface roughness.

  19. Flow Analysis of the Cleveland Clinic Centrifugal Pump

    NASA Technical Reports Server (NTRS)

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

    1997-01-01

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

  20. Viscous Little Rip Cosmology

    E-print Network

    I. Brevik; E. Elizalde; S. Nojiri; S. D. Odintsov

    2011-10-14

    Dark energy of phantom or quintessence nature with an equation of state parameter $w$ almost equal to -1 often leads the universe evolution to a finite-time future singularity. An elegant solution to this problem has been recently proposed \\cite{frampton11} under the form of the so-called Little Rip cosmology which appears to be a realistic alternative to the $\\Lambda$CDM model. A viscous Little Rip cosmology is here proposed. Whereas generically bulk viscosity tends to promote the Big Rip, we find that there are a number of situations where this is not the case and where the formalism nicely adjusts itself to the Little Rip scenario. We prove, in particular, that a viscous fluid (or, equivalently, one with an inhomogeneous (imperfect) equation of state) is perfectly able to produce a Little Rip cosmology as a purely viscosity effect. The possibility of its induction as a combined result of viscosity and a general (power-like) equation of state is also investigated in detail. To finish, a physical, inertial force interpretation of the dissolution of bound structures in the Little Rip cosmology is presented.

  1. Micropump for viscous liquids and muds

    NASA Astrophysics Data System (ADS)

    Schwesinger, Norbert; Bechtel, Sasha

    1998-09-01

    This work was focused on the development of a micropump that allows the transport of fluids with high viscosities or fluids containing pigments in a large amount. This new pump should be produced by means of silicon micromachining technologies. Due to adhesion forces as well as sedimentation processes the transport of highly viscous and particle loaded fluids is a difficult problem. Dead volumes must be surely avoided in the pump because they are preferred regions of adhesion and sedimentation, respectively. The developed micropump is nearly free of dead volumes. It consists of silicon chips and a PTFE-membrane bonded together without real gluing procedures. The silicon chips contain deep etched structures manufactured by simple wet chemical etching procedures. Pressure on the liquid can be generated inside the structures by pushing the elastic membrane. A pneumatic drive was used to deflect the membranes. In a peristaltic mode it was possible to pump liquids like honey or mustard with a noticeable flow rat up to 0.6 ml/min without any back flow.

  2. Viscous transonic flow over airfoils

    Microsoft Academic Search

    J. C. Wai; H. Yoshihara

    1981-01-01

    The TSFOIL small disturbance potential code is coupled to Green's lag entrainment method to compute transonic separated flows over airfoils. Green's equation serves as a viscous tangency condition for the TSFOIL code, eliminating an iterative procedure between the viscous and inviscid flows. The method is applied to the case of the NASA Supercritical Airfoil 12 and the 18% Circular Arc

  3. Experiment Study of the Internal Flow in Centrifugal Pump

    NASA Astrophysics Data System (ADS)

    Liu, D.; Wang, C. L.

    2011-09-01

    To study the phenomena of two-phase flow with salt-out in centrifugal pump, it is important to investigate the real flow in the pump with clear water. Based on the Reynolds-averaged N-S equations and standard ?-? two-equation turbulent model, the 3D turbulent flow was simulated through the full flow passage by the fluid dynamics software FLUENT.PIV was also applied to measure the flow inside the modified centrifugal pump. Relative velocity distributions in the impeller were obtained. Combined with the results from numerical simulation and experiment, preliminary analysis of inner flow field in the centrifugal pump was presented. The experiment results also show that standard ?-? turbulent model used in simulation coincides with the inner flow of the pump basically.

  4. Numerical investigation of unsteady turbulent flow in a centrifugal pump at partial load

    NASA Astrophysics Data System (ADS)

    Lei, T.; Baoshan, Z.; ShuLiang, C.; Yuchuan, W.; Xuhe, W.

    2014-03-01

    The unsteady non-cavitation and cavitation turbulent flows in a centrifugal pump at partial load condition are numerically investigated by CFX 13.0. The numerical framework employs the combination of RNG k-? turbulence model and transport equation cavitation model, in which the effects of compressibility of fluid on cavitation region and pressure fluctuation on saturation pressure are both taken into consideration. The good agreement between the numerical and experimental values validates that the numerical framework can accurately predict the turbulent flows in the centrifugal pump. The complex flow characteristics in impeller at non-cavitation and cavitation conditions are revealed. For the noncavitation flow, the dominant frequencies of pressure fluctuation of monitoring points in impeller are all the Impeller Rotation Frequency 24.17Hz. The maximum value of pressure fluctuation on the blade pressure side appears at the 0.8 chord length from the blade leading edge due to a clockwise rotating vortex, which incepts, develops and disappears when the corresponding blade passes through the volute tongue. The dominant frequencies of pressure fluctuation of monitoring points in volute are the Blade Pass Frequency 145 Hz or twice of it. The maximum value of pressure fluctuation in the volute appears near the tongue region, where the flow fields are uneven with strong second flow in the cross section. For the cavitation flow, as the cavitation develops at the blade leading edge, the turbulent flows in the impeller are greatly influenced by the bubble shedding and collapse. The maximum values of pressure fluctuation in impeller increase with the development of cavitation, and reach the largest magnification of about 2.0 in comparison to the non-cavitation flow when the pressure at the pump inlet is very low. The complicated phenomenon of unsteady turbulent flow in a centrifugal pump indicates that the vortex has great influence on the flow pattern.

  5. Viscous sludge sample collector

    DOEpatents

    Beitel, George A [Richland, WA

    1983-01-01

    A vertical core sample collection system for viscous sludge. A sample tube's upper end has a flange and is attached to a piston. The tube and piston are located in the upper end of a bore in a housing. The bore's lower end leads outside the housing and has an inwardly extending rim. Compressed gas, from a storage cylinder, is quickly introduced into the bore's upper end to rapidly accelerate the piston and tube down the bore. The lower end of the tube has a high sludge entering velocity to obtain a full-length sludge sample without disturbing strata detail. The tube's downward motion is stopped when its upper end flange impacts against the bore's lower end inwardly extending rim.

  6. A status of the activities of the NASA/MSFC pump stage technology team

    NASA Astrophysics Data System (ADS)

    Garcia, R.; Williams, R.; Dakhoul, Y.

    1992-07-01

    The Consortium for Computational Fluid Dynamics (CFD) Application in Propulsion Technology was established to aid the transfer of CFD related advancements among academia, government agencies, and industry. The specific goals of the Consortium are to develop CFD methodologies necessary to solve propulsion problems, to validate these methodologies, and to apply these methodologies in the design process. To accomplish these goals, a team of experts in various related fields was formed, a schedule of activities necessary to meet the goals was generated, and funding for the activities was obtained from NASA. During the past year (Mar. 1991 - Mar. 1992) the team's activities have focused on preliminary code validation and on the design of an advanced impeller. Six codes were used to calculate the flow in a Rocketdyne 0.3 flow coefficient inducer, and the results were compared to L2F data available for the inducer. This activity identified shortcomings in the experimental data sets and in the analytical solutions which must be surmounted in any future team activity. The design of the advanced impeller relied heavily on CFD results to obtain an optimized geometry. The optimized geometry was analyzed using four different codes, at design and off-design conditions. Activities for the next year include the optimization of a tandem blade impeller design, benchmark of CFD codes for diffuser and volute flows, the collection of L2F data for 'state-of-the-art' impeller and inducer, and the verification of the advanced pump team impeller design in a water rig.

  7. Inducer analysis/pump model development

    NASA Technical Reports Server (NTRS)

    Cheng, Gary C.

    1994-01-01

    Current design of high performance turbopumps for rocket engines requires effective and robust analytical tools to provide design information in a productive manner. The main goal of this study was to develop a robust and effective computational fluid dynamics (CFD) pump model for general turbopump design and analysis applications. A finite difference Navier-Stokes flow solver, FDNS, which includes an extended k-epsilon turbulence model and appropriate moving zonal interface boundary conditions, was developed to analyze turbulent flows in turbomachinery devices. In the present study, three key components of the turbopump, the inducer, impeller, and diffuser, were investigated by the proposed pump model, and the numerical results were benchmarked by the experimental data provided by Rocketdyne. For the numerical calculation of inducer flows with tip clearance, the turbulence model and grid spacing are very important. Meanwhile, the development of the cross-stream secondary flow, generated by curved blade passage and the flow through tip leakage, has a strong effect on the inducer flow. Hence, the prediction of the inducer performance critically depends on whether the numerical scheme of the pump model can simulate the secondary flow pattern accurately or not. The impeller and diffuser, however, are dominated by pressure-driven flows such that the effects of turbulence model and grid spacing (except near leading and trailing edges of blades) are less sensitive. The present CFD pump model has been proved to be an efficient and robust analytical tool for pump design due to its very compact numerical structure (requiring small memory), fast turnaround computing time, and versatility for different geometries.

  8. Heat pumps

    Microsoft Academic Search

    Heap

    1983-01-01

    An updated version of the 1979 first edition of this work for designers, specifiers, suppliers, installers, and users of heat pumps. Its aim is to assist in the reassessment of energy costs and cost relativities of the various applications of heat pumps. It presents the development of the heat pump markets, research into advanced heat pump systems, and development of

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

    NASA Astrophysics Data System (ADS)

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

    2013-04-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2014-03-01

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

  11. Design concept of a pump stage with replaceable hydraulic components and prediction of its performance curves

    NASA Astrophysics Data System (ADS)

    Lugova, S. O.; Knyazeva, E. G.; Tverdokhleb, I. B.; Kochevsky, A. N.

    2010-08-01

    In many cases, centrifugal pump units are expected to deliver the required performance under varying operating conditions. In particular, the pumps for oil extraction and transportation should deliver a constant head, although their capacity often changes during the life cycle. In order to keep the efficiency at a high level and not to replace a whole pump, the authors suggest to replace in such cases only hydraulic components of the pump (impellers and stationary sections of diffuser channels) that are to be installed in the same casing. The paper describes an approach for designing of radial-flow impellers and sections of diffuser channels to be used as replaceable. It allows for delivering a required head and providing a high efficiency in a wide range of capacities. The components intended for smaller capacities are featured with narrower flow passages. However, the dimensions of replaceable components are the same. The paper describes also a numerical simulation of fluid flow in a pump stage with two sets of replaceable radial-flow impellers and sections of diffuser channels. The CFD software used in this research is ANSYS CFX 11. Good correspondence of results is observed. Difference in flow pattern at various capacities and its influence on the performance curves delivered with replaceable components is demonstrated. Basing on the obtained results, the analysis of energy losses is presented.

  12. Cryogenic Viscous Compressor Development and Modeling for the ITER Vacuum System

    SciTech Connect

    Baylor, Larry R [ORNL; Meitner, Steven J [ORNL; Barbier, Charlotte N [ORNL; Combs, Stephen Kirk [ORNL; Duckworth, Robert C [ORNL; Edgemon, Timothy D [ORNL; Rasmussen, David A [ORNL; Hechler, Michael P [ORNL; Kersevan, R. [ITER Organization, Cadarache, France; Dremel, M. [General Atomics, San Diego; Pearce, R.J.H. [General Atomics, San Diego; Boissin, Jean Claude [Consultant

    2011-01-01

    The ITER vacuum system requires a roughing pump system that can pump the exhaust gas from the torus cryopumps to the tritium exhaust processing plant. The gas will have a high tritium content and therefore conventional vacuum pumps are not suitable. A pump called a cryogenic viscous compressor (CVC) is being designed for the roughing system to pump from ~500 Pa to 10 Pa at flow rates of 200 Pa-m3/ s. A unique feature of this pump is that is allows any helium in the gas to flow through the pump where it is sent to the detritiation system before exhausting to atmosphere. A small scale prototype of the CVC is being tested for heat transfer characteristics and compared to modeling results to ensure reliable operation of the full scale CVC. Keywords- ITER; vacuum; fuel cycle

  13. The experimental study of matching between centrifugal compressor impeller and diffuser

    SciTech Connect

    Tamaki, H.; Nakao, H.; Saito, M. [Ishikawajima-Harima Heavy Industries Co., Ltd., Tokyo (Japan). Turbomachinery and Engine Development Dept.

    1999-01-01

    the centrifugal compressor for a marine use turbocharger with its design pressure ratio of 3.2 was tested with a vaneless diffuser and various vaned diffusers. Vaned diffusers were chosen to cover impeller operating range as broad as possible. The analysis of the static pressure ratio in the impeller and the diffusing system, consisting of the diffuser and scroll, showed that there were four possible combinations of characteristics of impeller pressure ratio and diffusing system pressure ratio. The flow rate, Q{sub P}, where the impeller achieved maximum static pressure ratio, was surge flow rate of the centrifugal compressor determined by the critical flow rate. In order to operate the compressor at a rate lower than Q{sub P}, the diffusing system, whose pressure recovery factor was steep negative slope near Q{sub P}, was needed. When the diffuser throat area was less than a certain value, the compressor efficiency deteriorated; however, the compressor stage pressure ratio was almost constant. In this study, by reducing the diffuser throat area, the compressor could be operated at a flow rate less than 40% of its design flow rate. Analysis of the pressure ratio in the impeller and diffusing systems at design and off-design speeds showed that the irregularities in surge line occurred when the component that controlled the negative slope on the compressor stage pressure ratio changed.

  14. Culture of photomixotrophic soybean and pine in a modified fermentor using a novel impeller.

    PubMed

    Treat, W J; Engler, C R; Soltes, E J

    1989-11-01

    Photomixotrophic suspensions of Glycine max (soybean) and Pinus elliottii (slash pine) have been successfully cultured in a hybrid stirred tank photobioreactor using a novel cell-lift impeller. A cell-lift impeller exhibited cell viabilities over 90% and an average cell aggregate size of 1.0 mm or less. Flat-bladed turbines produced equivalent biomass to the cell-lift impeller, but cell viability was reduced (85%) and cell aggregate size increased (3-5 mm diameter). Maximum fresh weights of 82 g L(-1) (soybean) and 52 g L(-1) (slash pine) were achieved in 15 days using continuous lighting (90-100 microE m(-2) s(-1)) and supplemental 2% CO(2) inlet gas. Maximum biomass was achieved using an impeller speed of 60 rpm with air-flow rate of 0.2 vvm for the cell-lift impeller and the pair of flat bladed turbines. The lag and early exponential phases were characterized by (1) rapid hydrolysis of sucrose followed by preferential use of glucose and (2) a reduction in chlorophyll levels. Carbon dioxide (2%-5%) was an essential nutrient for photomixotrophic cell culture in the bioreactors. PMID:18588217

  15. TRANSIENT BEHAVIOR OF THE VISCOUS MICROPUMP

    Microsoft Academic Search

    M. Abdelgawad; I. Hassan; N. Esmail

    2004-01-01

    In the present study, the transient performance of the viscous micropump will be investigated numerically. The viscous micropump's operation depends mainly on viscous forces and can operate in any situation where viscous forces are dominant. All the micropump calculations are reported in nondimensional quantities, which allows for the prediction of the micropump performance, regardless of the dimensions or the fluid

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

    PubMed

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

    1994-01-01

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

  17. Impeller leakage flow modeling for mechanical vibration control

    NASA Technical Reports Server (NTRS)

    Palazzolo, Alan B.

    1996-01-01

    HPOTP and HPFTP vibration test results have exhibited transient and steady characteristics which may be due to impeller leakage path (ILP) related forces. For example, an axial shift in the rotor could suddenly change the ILP clearances and lengths yielding dynamic coefficient and subsequent vibration changes. ILP models are more complicated than conventional-single component-annular seal models due to their radial flow component (coriolis and centrifugal acceleration), complex geometry (axial/radial clearance coupling), internal boundary (transition) flow conditions between mechanical components along the ILP and longer length, requiring moment as well as force coefficients. Flow coupling between mechanical components results from mass and energy conservation applied at their interfaces. Typical components along the ILP include an inlet seal, curved shroud, and an exit seal, which may be a stepped labyrinth type. Von Pragenau (MSFC) has modeled labyrinth seals as a series of plain annular seals for leakage and dynamic coefficient prediction. These multi-tooth components increase the total number of 'flow coupled' components in the ILP. Childs developed an analysis for an ILP consisting of a single, constant clearance shroud with an exit seal represented by a lumped flow-loss coefficient. This same geometry was later extended to include compressible flow. The objective of the current work is to: supply ILP leakage-force impedance-dynamic coefficient modeling software to MSFC engineers, base on incompressible/compressible bulk flow theory; design the software to model a generic geometry ILP described by a series of components lying along an arbitrarily directed path; validate the software by comparison to available test data, CFD and bulk models; and develop a hybrid CFD-bulk flow model of an ILP to improve modeling accuracy within practical run time constraints.

  18. Well pumping

    SciTech Connect

    Bohon, W.M.

    1992-09-08

    This patent describes an apparatus for pumping a fluid from at least one geologic zone below the earth's surface through a wellbore that extends from at least the geologic zone to the earth's surface using at least one reciprocating downhole pump means in the wellbore, the downhole pump means being carried by elongate means which extends in the wellbore from the downhole pump means to the earth's surface, the downhole pump means and elongate means being reciprocated by a pumping unit located at or near the earth' surface. This patent describes improvement in at least one hydraulic pump means in the pumping unit to reciprocate the elongate means and downhole pump means in the wellbore.

  19. Viscous transonic flow over airfoils

    NASA Astrophysics Data System (ADS)

    Wai, J. C.; Yoshihara, H.

    The TSFOIL small disturbance potential code is coupled to Green's lag entrainment method to compute transonic separated flows over airfoils. Green's equation serves as a viscous tangency condition for the TSFOIL code, eliminating an iterative procedure between the viscous and inviscid flows. The method is applied to the case of the NASA Supercritical Airfoil 12 and the 18% Circular Arc Airfoil, the latter with severe separation.

  20. Cavitation indices for pumps in the Irtysh-Karaganda canal

    Microsoft Academic Search

    V. Ya. Karelin; R. A. Novoderezhkin

    1975-01-01

    Conclusions  \\u000a \\u000a \\u000a \\u000a 1. \\u000a \\u000a Cavitation on the walls of the internal passages of the OP10-185 and OP11-185 pumps occurs only on the impeller and at the\\u000a leading edges of the guide vanes. The extent of the cavitation zones increases with increasing deflection angles of the blades\\u000a and head of water and with decreasing degree of partial submergence of the impeller.\\u000a \\u000a \\u000a \\u000a \\u000a 2. \\u000a \\u000a With

  1. Viscous dark fluid universe

    SciTech Connect

    Hipolito-Ricaldi, W. S. [Universidade Federal do Espirito Santo, Departamento de Ciencias Matematicas e Naturais, CEUNES, Rodovia BR 101 Norte, km. 60, CEP 29932-540, Sao Mateus, Espirito Santo (Brazil); Velten, H. E. S.; Zimdahl, W. [Universidade Federal do Espirito Santo, Departamento de Fisica, Av. Fernando Ferrari, 514, Campus de Goiabeiras, CEP 29075-910, Vitoria, Espirito Santo (Brazil)

    2010-09-15

    We investigate the cosmological perturbation dynamics for a universe consisting of pressureless baryonic matter and a viscous fluid, the latter representing a unified model of the dark sector. In the homogeneous and isotropic background the total energy density of this mixture behaves as a generalized Chaplygin gas. The perturbations of this energy density are intrinsically nonadiabatic and source relative entropy perturbations. The resulting baryonic matter power spectrum is shown to be compatible with the 2dFGRS and SDSS (DR7) data. A joint statistical analysis, using also Hubble-function and supernovae Ia data, shows that, different from other studies, there exists a maximum in the probability distribution for a negative present value q{sub 0{approx_equal}}-0.53 of the deceleration parameter. Moreover, while previous descriptions on the basis of generalized Chaplygin-gas models were incompatible with the matter power-spectrum data since they required a much too large amount of pressureless matter, the unified model presented here favors a matter content that is of the order of the baryonic matter abundance suggested by big-bang nucleosynthesis.

  2. Viscous couplings enter mainstream vehicles

    SciTech Connect

    Barlage, J.A. (GKN Automotive Inc., Auburn Hills, MI (United States))

    1993-10-01

    This article discusses how the viscous coupling, which is now known mostly because of its use as a driveline component in four-wheel-drive vehicles, as a limited-slip differential in axles and transfer cases, and as a viscous transmission device, could become a major player in mainstream front-wheel-drive applications. Several factors are at work here. One is the fact that new external mounting techniques have made it possible to design viscous couplings into existing vehicles with minimal modifications. Another is that recent substantial reductions in cost and weight have made viscous couplings a more economical choice than in the past. However, perhaps the greatest impact has come from their use in vehicles such as the Lancia Thema, Nissan NX2000, and Honda Prelude, which have demonstrated that viscous couplings can significantly improve handling and stability even under normal driving conditions. When properly tuned and applied, viscous couplings can greatly reduce the need for driver correction of a vehicle's course under moderate- to high-speed driving conditions, especially on higher-powered front-wheel-drive vehicles.

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

    NASA Astrophysics Data System (ADS)

    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-in turbulence model by the density function, a computational model is developed to simulate cavitation flow of a centrifugal pump at low flow rate. The Navier-Stokes 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.

  4. Fluid dynamic design for low hemolysis in a hydrodynamically levitated centrifugal blood pump.

    PubMed

    Murashige, Tomotaka; Kosaka, Ryo; Nishida, Masahiro; Maruyama, Osamu; Yamane, Takashi; Kuwana, Katsuyuki; Kawaguchi, Yasuo

    2013-01-01

    We have developed a hydrodynamically levitated centrifugal blood pump for extracorporeal circulatory support as a bridge to decision pump. The impeller is levitated using hydrodynamic bearings without any complicated control circuit or displacement sensor. However, the effect of the outer circumferential velocity and the bearing area on the hemolytic property has not been clarified, even if the bearing gap is same size. The purpose of this study is to experimentally evaluate the effect of the outer circumferential velocity and the bearing area in the bearing gaps on the hemolytic property in a hydrodynamically levitated centrifugal blood pump. We prepared three models for testing. These models have the same bearing gap size by adjusting the impeller levitation position. However, the outer circumferential velocity of the impeller and the bearing area in the minimum bearing gaps are different. The outer circumferential velocity of the impeller and the bearing area were assumed to be related to the maximum shear rate and the exposure time. For the evaluation, we conducted an impeller levitation performance test and an in vitro hemolysis test. As a result, the normalized index of hemolysis (NIH) was reduced from 0.084 g/100 L to 0.040 g/100 L corresponding to a reduction in the outer circumferential velocity and a reduction in the bearing area, even if the minimum bearing gaps were same size. We confirmed that, even if the bearing gap was same size under the stably levitated condition, the outer circumferential velocity and the bearing area should be decreased in order to improve the hemolytic property. PMID:24110292

  5. A theoretical study of fluid forces on a centrifugal impeller rotating and whirling in a vaned diffuser

    NASA Technical Reports Server (NTRS)

    Tsujimoto, Yoshinobu; Acosta, Allan J.; Yoshida, Yoshiki

    1989-01-01

    The fluid forces on a centrifugal impeller rotating and whirling in a vaned diffuser are analyzed on the assumption that the number of impeller and diffuser vanes is so large that the flows are perfectly guided by the vanes. The flow is taken to be two dimensional, inviscid, and incompressible, but the effects of impeller and diffuser losses are taken into account. It is shown that the interaction with the vaned diffuser may cause destabilizing fluid forces. From these discussions, it is found that the whirling forces are closely related to the steady head-capacity characteristics of the impeller. This physical understanding of the whirling forces can be applied also to the cases with volute casings. At partial capacities, it is shown that the impeller forces change greatly when the flow rate and whirl velocity are near to the impeller or vaned diffuser attributed rotating stall onset capacity, and the stall propagation velocity, respectively. In such cases the impeller forces may become destabilizing for impeller whirl.

  6. Investigation of the effect of impeller speed on granules formed using a PMA-1 high shear granulator.

    PubMed

    Logan, R; Briens, L

    2012-11-01

    Impeller speed was varied from 300 to 1500 rpm during the wet high shear granulation of a placebo formulation using a new vertical shaft PharmaMATRIX-1 granulator. The resulting granules were extensively analysed for differences caused by the varying impeller speed with emphasis on flowability. Microscopy showed that initial granules were formed primarily from microcrystalline cellulose at all tested impeller speeds. At low impeller speed of 300 rpm in the "bumpy" flow regime, forces from the impeller were insufficient to incorporate all the components of the formulation into the granules and to promote granule growth to a size that significantly improved flowability. The "roping" flow regime at higher impeller speeds promoted granule growth to a median particle size of at least 100 µm that improved the flowability of the mixture. Particle size distribution measurements and advanced indicators based on avalanching behavior, however, showed that an impeller speed of 700 rpm produced the largest fraction of optimal granules with the best flowability potential. This impeller speed allowed good development of "roping" flow for sufficient mixing, collision rates and kinetic energy for collisions while minimizing excessive centrifugal forces that promote buildup around the bowl perimeter. PMID:22436101

  7. Design of a novel axial impeller as a part of counter-rotating axial compressor to compress water vapor as refrigerant

    Microsoft Academic Search

    Qubo Li; Janusz Piechna; Norbert Müller

    2011-01-01

    A systematic investigation to understand the use of a novel axial impeller as a part of counter-rotating axial compressor to compress water vapor as refrigerant was undertaken. Blade angle was investigated at first to understand this novel impeller’s geometry. A commercial CFD package, which solves the Reynolds-averaged Navier–Stokes equations, was used to compute the complex flow field of the impeller.

  8. Effects of inlet geometries on flow recirculation in an axial-flow pump 

    E-print Network

    Alpan, Kenan

    1984-01-01

    of the whole cooling, lubricating loop is given in Figure 12. 1 Oil'tilter 2 Motopump set 6 Pressure gauge 4 Thermomeler 6 Oll sump 6 Metal base plate 11 Heat exchanger 7 1/4 HP Motor 12 Water tank e Ftextbte coupling 13 Return pipe 9 Gear pump 14... were taken at different suction sections with varied flowrates to obtain the pumps' characteristic curves. Variations of the pump critical flowrate with different impeller inlet areas, suction piping and inlet guide vance were determined...

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

    NASA Astrophysics Data System (ADS)

    Fowler, H. S.

    1980-01-01

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

  10. CFD based rotordynamic coefficients for labyrinth seals and impeller leakage paths

    E-print Network

    Bhattacharya, Avijit

    1997-01-01

    of Turbomachin- ery Group, for their valuable technical discussions. I thank NASA and TRC for supporting this research. I would like to thank all my friends, who made my stay in College Station en- joyable. I would like to thank my sister, my parents and my... for Ettles Case D. Results for Ezzat and Rohde Case E. Results for Tieu's Case VI LEAKAGE PREDICTION OF IMPELLER (BOLLETER) A. Face Seal . . B. Wear Ring Seal VII IMPELLER SHROUD CASE (GUINZBURG) A. Model Description. B. Boundary Condition C. Results...

  11. Investigation of the jet-wake flow of a highly loaded centrifugal compressor impeller

    NASA Technical Reports Server (NTRS)

    Eckardt, D.

    1978-01-01

    Investigations, aimed at developing a better understanding of the complex flow field in high performance centrifugal compressors were performed. Newly developed measuring techniques for unsteady static and total pressures as well as flow directions, and a digital data analysis system for fluctuating signals were thoroughly tested. The loss-affected mixing process of the distorted impeller discharge flow was investigated in detail, in the absolute and relative system, at impeller tip speeds up to 380 m/s. A theoretical analysis proved good coincidence of the test results with the DEAN-SENOO theory, which was extended to compressible flows.

  12. Simulation of laminar and turbulent impeller stirred tanks using immersed boundary method and large eddy simulation technique in multi-block curvilinear geometries

    Microsoft Academic Search

    Mayank Tyagi; Somnath Roy; Albert D. Harvey III; Sumanta Acharya

    2007-01-01

    Impeller stirred tanks are commonly used in the chemical processing industries (CPI) for a variety of mixing and blending technologies. Such processes require accurate modeling of the turbulent flow in the tank over a range of operating conditions (e.g. impeller speed), and in addition, require a computationally efficient solution strategy that can represent moving rigid geometric parts (impellers) in the

  13. Magnetocaloric pump

    NASA Technical Reports Server (NTRS)

    Brown, G. V.

    1973-01-01

    Very cold liquids and gases such as helium, neon, and nitrogen can be pumped by using magnetocaloric effect. Adiabatic magnetization and demagnetization are used to alternately heat and cool slug of pumped fluid contained in closed chamber.

  14. Computation of stress distribution in a mixed flow pump based on fluid-structure interaction analysis

    NASA Astrophysics Data System (ADS)

    Hu, F. F.; Chen, T.; Wu, D. Z.; Wang, L. Q.

    2013-12-01

    The internal flow evolution of the pump was induced with impeller movement. In various conditions, the peak load on centrifugal blade under the change of rotational speed or flow rate was also changed. It would cause an error when inertia load with a safety coefficient (that was difficult to ascertain) was applied in structure design. In order to accurately analyze the impeller stress under various conditions and improve the reliability of pump, based on a mixed flow pump model, the stress distribution characteristic was analyzed under different flow rates and rotational speeds. Based on a three-dimensional calculation model including impeller, guide blade, inlet and outlet, the three-dimension incompressible turbulence flow in the centrifugal pump was simulated by using the standard k-epsilon turbulence model. Based on the sequentially coupled simulation approach, a three-dimensional finite element model of impeller was established, and the fluid-structure interaction method of the blade load transfer was discussed. The blades pressure from flow simulation, together with inertia force acting on the blade, was used as the blade loading on solid surface. The Finite Element Method (FEM) was used to calculate the stress distribution of the blade respectively under inertia load, or fluid load, or combined load. The results showed that the blade stress changed with flow rate and rotational speed. In all cases, the maximum stress on the blade appeared on the pressure side near the hub, and the maximum static stress increased with the decreasing of the flow rate and the increasing of rotational speed. There was a big difference on the static stress when inertia load, fluid load and combined loads was applied respectively. In order to more accurately calculate the stress distribution, the structure analysis should be conducted due to combined loads. The results could provide basis for the stress analysis and structure optimization of pump.

  15. Unsteady flow characteristic of low-specific-speed centrifugal pump under different flow-rate conditions

    NASA Astrophysics Data System (ADS)

    Cui, Baoling; Chen, Desheng; Xu, Wenjing; Jin, Yingzi; Zhu, Zuchao

    2015-02-01

    To investigate the unsteady flow characteristics in centrifugal pump, the flow field in a low-specific-speed centrifugal pump with complex impeller is numerically simulated under different conditions. The RNG ?-? turbulence model and sliding mesh are adopted during the process of computation. The results show that the interaction between impeller and volute results in the unstable flow of the fluid, which causes the uneven distribution of pressure fluctuations around the circumference of volute. Besides the main frequency and its multiple frequency of pressure fluctuations in the centrifugal pump, the frequency caused by the long blades of complex impeller also plays a dominant role in the low-frequency areas. Furthermore, there exists biggish fluctuation phenomenon near the tongue. The composition of static pressure fluctuations frequency on the volute wall and blade outlet is similar except that the fluctuation amplitude near the volute wall reduces. In general, the different flow rates mainly have influence on the amplitude of fluctuation frequency in the pump, while have little effect on the frequency composition.

  16. Study of a centrifugal blood pump in a mock loop system.

    PubMed

    Uebelhart, Beatriz; da Silva, Bruno Utiyama; Fonseca, Jeison; Bock, Eduardo; Leme, Juliana; da Silva, Cibele; Leão, Tarcísio; Andrade, Aron

    2013-11-01

    An implantable centrifugal blood pump (ICBP) is being developed to be used as a ventricular assist device (VAD) in patients with severe cardiovascular diseases. The ICBP system is composed of a centrifugal pump, a motor, a controller, and a power supply. The electricity source provides power to the controller and to a motor that moves the pump's rotor through magnetic coupling. The centrifugal pump is composed of four parts: external conical house, external base, impeller, and impeller base. The rotor is supported by a pivot bearing system, and its impeller base is responsible for sheltering four permanent magnets. A hybrid cardiovascular simulator (HCS) was used to evaluate the ICBP's performance. A heart failure (HF) (when the heart increases beat frequency to compensate for decrease in blood flow) was simulated in the HCS. The main objective of this work is to analyze changes in physiological parameters such as cardiac output, blood pressure, and heart rate in three situations: healthy heart, HF, and HF with left circulatory assistance by ICBP. The results showed that parameters such as aortic pressure and cardiac output affected by the HF situation returned to normal values when the ICBP was connected to the HCS. In conclusion, the test results showed satisfactory performance for the ICBP as a VAD. PMID:24237361

  17. Optical Pumping

    Microsoft Academic Search

    William Happer

    1972-01-01

    Optical pumping of ground-state and metastable atoms and ions is reviewed. We present a critical survey of the literature on pumping mechanisms, light propagation, relaxation mechanisms, spin exchange, and experimental details on the various atomic species which have been successfully pumped.

  18. Gyro-effect stabilizes unstable permanent maglev centrifugal pump.

    PubMed

    Qian, Kun-Xi

    2007-03-01

    According to Earnshaw's Theorem (1839), the passive maglev cannot achieve stable equilibrium and thus an extra coil is needed to make the rotor electrically levitated in a heart pump. The author had developed a permanent maglev centrifugal pump utilizing only passive magnetic bearings, to keep the advantages but to avoid the disadvantages of the electric maglev pumps. The equilibrium stability was achieved by use of so-called "gyro-effect": a rotating body with certain high speed can maintain its rotation stably. This pump consisted of a rotor (driven magnets and an impeller), and a stator with motor coil and pump housing. Two passive magnetic bearings between rotor and stator were devised to counteract the attractive force between the motor coil iron core and the rotor driven magnets. Bench testing with saline demonstrated a levitated rotor under preconditions of higher than 3,250 rpm rotation and more than 1 l/min pumping flow. Rotor levitation was demonstrated by 4 Hall sensors on the stator, with evidence of reduced maximal eccentric distance from 0.15 mm to 0.07 mm. The maximal rotor vibration amplitude was 0.06 mm in a gap of 0.15 mm between rotor and stator. It concluded that Gyro-effect can help passive maglev bearings to achieve stabilization of permanent maglev pump; and that high flow rate indicates good hydraulic property of the pump, which helps also the stability of passive maglev pump. PMID:17380386

  19. 241-SY-101 mixer pump lifetime expectancy. Final report

    SciTech Connect

    Shaw, C.P. [Science Applications International Corp., San Diego, CA (United States)

    1995-12-08

    The purpose of WHC-SD-WM-TI-726, Rev. 0 241-SY-101 Mixer Pump Lifetime Expectancy is to determine a best estimate of the mean lifetime of non-repairable (located in the waste) essential features of the hydrogen mitigation mixer pump presently installed in 101-SY. The estimated mean lifetime is 9.1 years. This report does not demonstrate operation of the entire pump assembly within the Tank Farm ``safety envelope``. It was recognized by the Defense Nuclear Facilities Safety Board (DNFSB) this test pump was not specifically designed for long term service in tank 101-SY. In June 95 the DNFSB visited Hanford and ask the question, ``how long will this test pump last and how will the essential features fail?`` During the 2 day meeting with the DNFSB it was discussed and defined within the meeting just exactly what essential features of the pump must operate. These essential features would allow the pump to operate for the purpose of extending the window for replacement. Operating with only essential features would definitely be outside the operating safety envelope and would require a waiver. There are three essential features: 1. The pump itself (i.e. the impeller and motor) must operate 2. Nozzles and discharges leg must remain unplugged 3. The pump can be re-aimed, new waste targeted, even if manually.

  20. Pump It!

    NSDL National Science Digital Library

    Integrated Teaching and Learning Program,

    Pumps are used to get drinking water to our houses every day! And in disaster situations, pumps are essential to keep flood water out. In this hands-on activity, student groups design, build, test and improve devices to pump water as if they were engineers helping a rural village meet their drinking water supply. Students keep track of their materials costs, and calculate power and cost efficiencies of the prototype pumps. They also learn about different types of pumps, how they work and useful applications.

  1. Remotely maintained waste transfer pump

    SciTech Connect

    Eargle, J.C.

    1990-12-31

    Westinghouse Savannah River Company (WSRC) operates the Savannah River Site (SRS) for the Department of Energy (DOE). Waste from the processing of irradiated material is stored in large shielded tanks. Treated liquid wastes are to be transferred from these tanks to the Defense Waste Processing Facility (DWPF) for incorporation in glass suitable for storage in a federal repository. Characteristics of the wastes range from water-like liquid to highly viscous wastes containing suspended solids. Pumping head requirements for various conditions ranged from 10 meters (35 feet) to 168 meters (550 feet). A specially designed, cantilever type, remotely operated and maintained pump was designed and built to transfer the wastes. To demonstrate the design, a prototype pump was built and testing thoroughly with simulated waste. Severe vibration problems were overcome by proper drive shaft selection and careful control of the space between the pump shaft and fixed running clearances (sometimes called seals). Eleven pumps are now installed and six pumps have been successfully run in water service.

  2. Remotely maintained waste transfer pump

    SciTech Connect

    Eargle, J.C.

    1990-01-01

    Westinghouse Savannah River Company (WSRC) operates the Savannah River Site (SRS) for the Department of Energy (DOE). Waste from the processing of irradiated material is stored in large shielded tanks. Treated liquid wastes are to be transferred from these tanks to the Defense Waste Processing Facility (DWPF) for incorporation in glass suitable for storage in a federal repository. Characteristics of the wastes range from water-like liquid to highly viscous wastes containing suspended solids. Pumping head requirements for various conditions ranged from 10 meters (35 feet) to 168 meters (550 feet). A specially designed, cantilever type, remotely operated and maintained pump was designed and built to transfer the wastes. To demonstrate the design, a prototype pump was built and testing thoroughly with simulated waste. Severe vibration problems were overcome by proper drive shaft selection and careful control of the space between the pump shaft and fixed running clearances (sometimes called seals). Eleven pumps are now installed and six pumps have been successfully run in water service.

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

    NASA Astrophysics Data System (ADS)

    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.

  4. Analysis of Impellers' Strength in the Flat Hydrodynamic Torque Converter for Passenger Car Based on CFD

    Microsoft Academic Search

    Chu Yaxu; Wu Xiangqiang; Liu Chunbao

    2010-01-01

    A new analysis method was suggested based on the numerical solutions of the 3-dimensional flow field to analyze accurately the strength of impeller in the flat hydrodynamic torque converter for passenger car. The 3-dimensional flow govern equations were solved numerically by means of a computational fluid dynamics (CFD) software, and on the basis of the obtained numerical solution of the

  5. Bulk-Flow analysis for force and moment coefficients of a shrouded centrifugal compressor impeller

    E-print Network

    Gupta, Manoj Kumar

    2005-08-29

    ???????????????????????????. 79 APPENDIX B??????????????????????????? 81 APPENDIX C??????????????????????????? 91 VITA??????????????????????????????? 95 ix LIST OF FIGURES FIGURE 1 Multistage centrifugal... for the exit wearing ring seal. Ci Initial (s=0) clearance. (m) f=?/? Nondimensional frequency ratio. h = H/Ci Nondimensional clearance. H Clearance between impeller shroud and housing. (m) L Axial path length. (m) Ls Leakage path...

  6. The prediction of design and off-design efficiency for centrifugal compressor impellers

    Microsoft Academic Search

    D. S. Musgrave

    1979-01-01

    Losses in centrifugal compressor impellers stem from a number of sources and their exact calculation is not yet possible. This paper investigates several modeling schemes and shows that a fair-to-good prediction (within a point or two) can be achieved by the selection of the most important flow parameters resulting from a meanline (inlet and exit) analysis.

  7. Comparing the performances of circular ponds with different impellers by CFD simulation and microalgae culture experiments.

    PubMed

    Meng, Chen; Huang, Jianke; Ye, Chunyu; Cheng, Wenchao; Chen, Jianpei; Li, Yuanguang

    2015-07-01

    In this study, a numerical simulation using computational fluid dynamics (CFD) was used to investigate the hydrodynamic characteristics of circular ponds with three different impellers (hydrofoil, four-pitched-blade turbine, and grid plate). The reliability of the CFD model was validated by particle image velocimetry (PIV). Hydrodynamic analyses were conducted to evaluate the average velocity magnitude along the light direction (U z), turbulence properties, average shear stress, pressure loss and the volume percentage of dead zone inside circular ponds. The simulation results showed that U z value of hydrofoil was 58.9, 40.3, and 28.8 % higher than those of grid plate with single arm, grid plate with double arms and four-pitched blade turbines in small-scale circular ponds, respectively. In addition, hydrofoil impeller with down-flow operation had outstanding mixing characteristics. Lastly, the results of Chlorella pyrenoidosa cultivation experiments indicated that the biomass concentration of hydrofoil impeller with down-flow operation was 65.2 and 88.8 % higher than those of grid plate with double arms and four-pitched-blade turbine, respectively. Therefore, the optimal circular pond mixing system for microalgae cultivation involved a hydrofoil impeller with down-flow operation. PMID:25680396

  8. Influence of bearing support structures on shaft vibration of large hydraulic pump/turbines

    SciTech Connect

    Pistner, C.A.; Greenplate, B.S. [Voith, Hydro, Inc., Pennsylvania, PA (United States); Waddell, A.M. [Tennessee Valley Authority, Chattanooga, TN (United States)

    1995-12-31

    Start-up transient loads from pump/turbine impellers can cause excessive vibration problems in the shaft system. If the radial guide bearing supports are structurally soft or loose, or if the bearings are worn, the resulting radial shaft movement causes abnormal wear. The wear normally occurs at the impeller sealing surfaces, main shaft seals, motor/generator components, piping, brackets, foundation connections, etc. This paper explores the critical factors causing shaft system vibration problems at the Tennessee Valley Authority`s Raccoon Mountain Pumped Storage Plant, as well as the unique modifications which were implemented to strengthen and improve the units. The solution involved extensive three-dimensional finite element structural and thermal transient analyses of the original and re-designed turbine shoe bearing, bearing housings, and support structures. The conclusion compares the calculated and measured shaft system response to transient loads of the original and modified system.

  9. Cavitation performance improvement of high specific speed mixed-flow pump

    NASA Astrophysics Data System (ADS)

    Chen, T.; Sun, Y. B.; Wu, D. Z.; Wang, L. Q.

    2012-11-01

    Cavitation performance improvement of large hydraulic machinery such as pump and turbine has been a hot topic for decades. During the design process of the pumps, in order to minimize size, weight and cost centrifugal and mixed-flow pump impellers are required to operate at the highest possible rotational speed. The rotational speed is limited by the phenomenon of cavitation. The hydraulic model of high-speed mixed-flow pump with large flow rate and high pumping head, which was designed based on the traditional method, always involves poor cavitation performance. In this paper, on the basis of the same hydraulic design parameters, two hydraulic models of high-speed mixed-flow pump were designed by using different methods, in order to investigate the cavitation and hydraulic performance of the two models, the method of computational fluid dynamics (CFD) was adopted for internal flow simulation of the high specific speed mixed-flow pump. Based on the results of numerical simulation, the influences of impeller parameters and three-dimensional configuration on pressure distribution of the blades' suction surfaces were analyzed. The numerical simulation results shows a better pressure distribution and lower pressure drop around the leading edge of the improved model. The research results could provide references to the design and optimization of the anti-cavitation blade.

  10. Viscous flow on hairy surfaces

    NASA Astrophysics Data System (ADS)

    Bartenwerfer, M.; Bechert, D. W.

    1991-02-01

    Viscous flow on a hairy surface is investigated analytically. This flow can be the viscous sublayer of a turbulent boundary layer. The hairy surface is modeled with strings stretched in the streamwise direction above a plate. Velocity and shear stress distributions are calculated. As a by-product, the theory provides orthogonal grids which may be utilized in future numerical flow computations. The distance of the apparent origin of the velocity profile from the surface is determined. This distance characterizes how deep the strings protrude into the flow. It is found that thin strings protrude much deeper into the flow than normal riblets do. For the latter, drag reduction has been shown experimentally.

  11. Method for producing viscous hydrocarbons

    DOEpatents

    Poston, Robert S. (Winter Park, FL)

    1982-01-01

    A method for recovering viscous hydrocarbons and synthetic fuels from a subterranean formation by drilling a well bore through the formation and completing the well by cementing a casing means in the upper part of the pay zone. The well is completed as an open hole completion and a superheated thermal vapor stream comprised of steam and combustion gases is injected into the lower part of the pay zone. The combustion gases migrate to the top of the pay zone and form a gas cap which provides formation pressure to produce the viscous hydrocarbons and synthetic fuels.

  12. Heart Pump Design for Cleveland Clinic Foundation

    NASA Technical Reports Server (NTRS)

    2005-01-01

    Through a Lewis CommTech Program project with the Cleveland Clinic Foundation, the NASA Lewis Research Center is playing a key role in the design and development of a permanently implantable, artificial heart pump assist device. Known as the Innovative Ventricular Assist System (IVAS), this device will take on the pumping role of the damaged left ventricle of the heart. The key part of the IVAS is a nonpulsatile (continuous flow) artificial heart pump with centrifugal impeller blades, driven by an electric motor. Lewis is part of an industry and academia team, led by the Ohio Aerospace Institute (OAI), that is working with the Cleveland Clinic Foundation to make IVAS a reality. This device has the potential to save tens of thousands of lives each year, since 80 percent of heart attack victims suffer irreversible damage to the left ventricle, the part of the heart that does most of the pumping. Impeller blade design codes and flow-modeling analytical codes will be used in the project. These codes were developed at Lewis for the aerospace industry but will be applicable to the IVAS design project. The analytical codes, which currently simulate the flow through the compressor and pump systems, will be used to simulate the flow within the blood pump in the artificial heart assist device. The Interdisciplinary Technology Office heads up Lewis' efforts in the IVAS project. With the aid of numerical modeling, the blood pump will address many design issues, including some fluid-dynamic design considerations that are unique to the properties of blood. Some of the issues that will be addressed in the design process include hemolysis, deposition, recirculation, pump efficiency, rotor thrust balance, and bearing lubrication. Optimum pumping system performance will be achieved by modeling all the interactions between the pump components. The interactions can be multidisciplinary and, therefore, are influenced not only by the fluid dynamics of adjacent components but also by thermal and structural effects. Lewis-developed flow-modeling codes to be used in the pump simulations will include a one-dimensional code and an incompressible three-dimensional Navier-Stokes flow code. These codes will analyze the prototype pump designed by the Cleveland Clinic Foundation. With an improved understanding of the flow phenomena within the prototype pump, design changes to improve the performance of the pump system can be verified by computer prior to fabrication in order to reduce risks. The use of Lewis flow modeling codes during the design and development process will improve pump system performance and reduce the number of prototypes built in the development phase. The first phase of the IVAS project is to fully develop the prototype in a laboratory environment that uses a water/glycerin mixture as the surrogate fluid to simulate blood. A later phase of the project will include testing in animals for final validation. Lewis will be involved in the IVAS project for 3 to 5 years.

  13. Fjords in viscous fingering: selection of width and opening scale

    SciTech Connect

    Mineev-weinstein, Mark [Los Alamos National Laboratory; Ristroph, Leif [UT-AUSTIN; Thrasher, Matthew [UT-AUSTIN; Swinney, Harry [UT-AUSTIN

    2008-01-01

    Our experiments on viscous fingering of air into oil contained between closely spaced plates reveal two selection rules for the fjords of oil that separate fingers of air. (Fjords are the building blocks of solutions of the zero-surface-tension Laplacian growth equation.) Experiments in rectangular and circular geometries yield fjords with base widths {lambda}{sub c}/2, where {lambda}{sub c} is the most unstable wavelength from a linear stability analysis. Further, fjords open at an angle of 8.0{sup o}{+-}1.0{sup o}. These selection rules hold for a wide range of pumping rates and fjord lengths, widths, and directions.

  14. Quantifying mixing in viscously unstable porous media flows

    E-print Network

    Jha, Birendra

    Viscous fingering is a well-known hydrodynamic instability that sets in when a less viscous fluid displaces a more viscous fluid. When the two fluids are miscible, viscous fingering introduces disorder in the velocity field ...

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

    NASA Technical Reports Server (NTRS)

    Pampreen, R. C.

    1977-01-01

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

  16. Viscous sintering of volcanic ash

    NASA Astrophysics Data System (ADS)

    Wadsworth, F. B.; Scheu, B.; Vasseur, J.; Tuffen, H.; von Aulock, F. W.; Lavallée, Y.; Hess, K. U.; Dingwell, D. B.

    2014-12-01

    Volcanic ash is often deposited in a hot state. Volcanic ash containing glass, deposited above the glass transition interval, has the potential to sinter viscously both to itself (particle-particle) and to exposed surfaces. Here, we constrain the kinetics of this process experimentally under isothermal and non-isothermal conditions using standard glasses and volcanic ash. In the absence of external load, this process is dominantly driven by surface relaxation. In such cases the sintering process is rate-limited by the melt viscosity, the size of the particles and the melt-vapour interfacial tension. We propose a polydisperse continuum model that describes the transition from a packing of particles to a dense pore-free melt and evaluate its efficacy in describing the kinetics of volcanic viscous sintering. We apply our model to viscous sintering scenarios for cooling crystal-poor rhyolitic ash using the 2008 eruption of Chaitén volcano as a case example. We predict that moderate cooling rates result in the common observation of incomplete sintering and the preservation of pore networks. Finally we discuss the effect of crystallisation, external loading and volatile degassing or regassing during viscous sintering and assert that such complexities must be considered in the volcanic scenario.

  17. AIAA 20033498 Viscous Aerodynamic Shape

    E-print Network

    Jameson, Antony

    design tool, but as an aid to analyze the fluid flow. The design process has still been done by trial for aerodynamic shape design in viscous compressible flow mod- eled by the Navier-Stokes equations. It extends, a Pareto front is captured, broadening the design range of optimal shapes. INTRODUCTION CFD has played

  18. Dark Energy and Viscous Cosmology

    E-print Network

    I. Brevik; O. Gorbunova

    2005-08-11

    Singularities in the dark energy universe are discussed, assuming that there is a bulk viscosity in the cosmic fluid. In particular, it is shown how the physically natural assumption of letting the bulk viscosity be proportional to the scalar expansion in a spatially flat FRW universe can drive the fluid into the phantom region (w -1) in the non-viscous case.

  19. Genetic relatedness in viscous populations

    Microsoft Academic Search

    David C. Queller

    1994-01-01

    Summary Hamilton's inclusive fitness rule shows that the evolution of altruism is facilitated by high genetic relatedness of altruists to their beneficiaries. But the evolution of altruism is inhibited when the beneficiaries are also close competitors of the altruist, as will often be true in structured or viscous populations. However, Hamilton's rule still gives the correct condition for the evolution

  20. Optimization of centrifugal pump cavitation performance based on CFD

    NASA Astrophysics Data System (ADS)

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

    2015-01-01

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

  1. A novel electro-osmotic pump design for nonconducting liquids: theoretical analysis of flow rate pressure characteristics and stability

    NASA Astrophysics Data System (ADS)

    Brask, Anders; Goranovic, Goran; Jensen, Mads Jakob; Bruus, Henrik

    2005-04-01

    We present the design and theoretical analysis of a novel electro-osmotic (EO) pump for pumping nonconducting liquids. Such liquids cannot be pumped by conventional EO pumps. The novel type of pump, which we term the two-liquid viscous EO pump, is designed to use a thin layer of conducting pumping liquid driven by electro-osmosis to drag a nonconducting working liquid by viscous forces. Based on computational fluid dynamics, our analysis predicts a characteristic flow rate of the order nL/s/V and a pressure capability of the pump in the hPa/V range depending on, of course, achievable geometries and surface chemistry. The stability of the pump is analyzed in terms of the three instability mechanisms that result from shear-flow effects, electrohydrodynamic interactions and capillary effects. Our linear stability analysis shows that the interface is stabilized by the applied electric field and by the small dimensions of the micropump.

  2. Small centrifugal pumps for low-thrust rocket engines

    NASA Technical Reports Server (NTRS)

    Furst, R. B.

    1986-01-01

    Six small, low specific speed centrifugal pump configurations were designed, fabricated, and tested. The configurations included shrouded, and 25 and 100% admission open face impellers with 2 inch tip diameters; 25, 50, and 100% emission vaned diffusers; and volutes with conical exits. Impeller tip widths varied from 0.030 inch to 0.052 inch. Design specific speeds (N sub s = RPM*GPM**0.5.FT**0.75) were 430 (four configurations) and 215 (two configurations). The six configurations were tested with water as the pumped fluid. Noncavitating performance results are presented for the design speed of 24,500 rpm over a flowrate range from 1 to 6 gpm for the N sub s = 430 configurations and test speeds up to 29,000 rpm over a flowrate range from 0.3 to 1.2 gpm for the N sub s = 215 configurations. Cavitating performance results are presented over a flowrate range from 60 to 120% of design flow. Fabrication of the small pump conponents is also discussed.

  3. Development of the Valvo pump: an axial flow pump implanted at the heart valve position.

    PubMed

    Mitamura, Y; Nakamura, H; Okamoto, E; Yozu, R; Kawada, S; Kim, D W

    1999-06-01

    Pulsatile artificial hearts having a relatively large volume are difficult to implant in a small patient, but rotary blood pumps can be easily implanted. The objective of this study was to show the feasibility of using the Valvo pump, an axial flow pump implanted at the heart valve position, in such cases. The Valvo pump consists of an impeller and a motor. The motor is waterproofed with a ferrofluidic seal. A blood flow of 5 L/min was obtained at a pressure difference of 13.3 kPa (100 mm Hg) at 7,000 rpm. The normalized index of hemolysis (NIH) was 0.030 +/- 0.003 (n = 3) for a blood flow of 5 L/min at a pressure difference of 13.3 kPa. The pressure resistance of the ferrofluidic seal was 37.5 kPa in a static condition and 26.3 kPa at 10,000 rpm. The seal exhibited no leaks for 41+ days against 20.0 kPa. The results showed that the Valvo pump can maintain systemic circulation with an acceptable level of hemolysis. PMID:10392286

  4. Vibration assessment for thrombus formation in the centrifugal pump.

    PubMed

    Nakazawa, T; Makinouchi, K; Takami, Y; Glueck, J; Tayama, E; Nosé, Y

    1997-04-01

    To clarify the correlation of vibration and thrombus formation inside a rotary blood pump, 40 preliminary vibration studies were performed on pivot bearing centrifugal pumps. No such studies were found in the literature. The primary data acquisition equipment included an accelerometer (Isotron PE accelerometer, ENDEVCO, San Juan Capistrano, CA, U.S.A.), digitizing oscilloscope (TDS 420, Tektronix Inc., Pittsfield, MA, U.S.A.), and pivot bearing centrifugal pumps. The pump impeller was coupled magnetically to the driver magnet. The accelerometer was mounted on the top of the pump casing to sense radial and axial accelerations. To simulate the 3 common areas of thrombus formation, a piece of silicone rubber was attached to each of the following 3 locations as described: a circular shape on the center bottom of the impeller (CI), an eccentric shape on the bottom of the impeller (EI), and a circular shape on the center bottom casing (CC). A fast Fourier transform (FFT) method at 5 L/min against 100 mm Hg, with a pump rotating speed of 1,600 rpm was used. The frequency response of the vibration sensors used spans of 40 Hz to 2 kHz. The frequency domain was already integrated into the oscilloscope, allowing for comparison of the vibration results. The area of frequency domain at a radial direction was 206 +/- 12.7 mVHz in CI, 239.5 +/- 12.1 mVHz in EI, 365 +/- 12.9 mVHz in CC, and 163 +/- 7.9 mVHz in the control (control vs. CI p = 0.07, control vs. EI p < 0.001, control vs. CC p < 0.001, EI vs. CC p < 0.001, CI vs. CC p < 0.001). Three types of imitation thrombus formations were roughly distinguishable. These results suggested the possibility of detecting thrombus formation using vibration signals, and these studies revealed the usefulness of vibration monitoring to detect thrombus formation in a centrifugal pump. PMID:9096805

  5. Noise and vibration generated by cavitation in an axial-flow pump

    SciTech Connect

    Saito, Sumio [Ebara Research Company, Limited, Tokyo (Japan). Dept. of Hydrodynamics Research and Development

    1994-12-31

    The relationship between pump performance and noise and vibration generated by cavitation was investigated using an axial-flow impeller. At first, the cavitation pattern was classified into four types which are concerned with the area of cavitation occurrence and pump operating conditions relative to pump performance. Pump performance, especially changes in the pump head and the shaft power curves are clearly related to the extent of cavitation growth on the suction side of the blades. The spectrum of pressure measured on the impeller casing depends mainly on the tip clearance cavitation development. Levels of high frequency component over 1 kHz increase remarkable as cavitation grows, and there are no discrete components in the high frequency range. Casing vibration and cavitation noise are concluded to be brought about by pressure fluctuations. From the total point of view of cavitation shock pressure, pressure fluctuation, casing vibration and air-borne noise, one type of index is proposed for the limitation of pump operation under cavitation conditions instead of the 3% head drop point.

  6. Heat pumps

    Microsoft Academic Search

    R. D. Heap

    1979-01-01

    With increasing energy costs and changing cost relativities, potential heat pump applications deserve a thorough reassessment. Such a reassessment is the objective of this book. The topics covered include the general, historical, and theoretical background material; vapor compression equipment; general aspects of system design, with particular reference to the design of space heating systems employing heat pumps; domestic, commercial, and

  7. Effects of normal viscous stresses on radial viscous fingering.

    PubMed

    Gadêlha, Hermes; Miranda, José A

    2009-06-01

    We revisit the radial viscous fingering problem in a Hele-Shaw cell, and consider the action of viscous stresses originated from velocity gradients normal to the fluid-fluid interface. The evolution of the interface during linear and weakly nonlinear stages is described analytically through a mode-coupling approach. We find that the introduction of normal stresses influences the stability and the ultimate morphology of the emerging patterns. Although at early stages normal stresses tend to stabilize the interface, they act to favor the development of tip-splitting phenomena at the weakly nonlinear regime. We have also verified that finger competition events are only significantly affected by normal stresses for circumstances involving the development of a large number of interfacial fingers. PMID:19658599

  8. Ferroelectric Pump

    NASA Technical Reports Server (NTRS)

    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.

  9. Effect of blade wrap angle on efficiency and noise of small radial fan impellers—A computational and experimental study

    NASA Astrophysics Data System (ADS)

    Scheit, C.; Karic, B.; Becker, S.

    2012-02-01

    Radial impellers have several technical applications. Regarding their aerodynamic performance, they are well optimized nowadays, but this is in general not true regarding acoustics. This work was therefore concerned with analyzing the flow structures inside isolated radial impellers together with the far-field sound radiated from them in order to optimize the aerodynamic and acoustic performance. Both numerical and experimental techniques were applied in order to study the effect of varying wrap angle and otherwise identical geometric configuration on aerodynamics and acoustics of the radial impellers. The results give a detailed insight into the processes leading to sound generation in radial impellers. Measurements were performed using laser Doppler anemometry for the flow field and microphone measurements to analyze the radiated noise. In addition, unsteady aerodynamic simulations were carried out to calculate the compressible flow field. An acoustic analogy was employed to compute far-field noise. Finally, the phenomena responsible for tonal noise and the role of the wrap angle could be identified. Using this knowledge, design guidelines are given to optimize the impeller with respect to the radiated noise. This work shows that improved aerodynamic efficiency for isolated impellers does not automatically lead to a smaller flow-induced sound radiation.

  10. Fully three-dimensional and viscous semi-inverse method for axial/radial turbomachine blade design

    NASA Astrophysics Data System (ADS)

    Ji, Min

    2008-10-01

    A fully three-dimensional viscous semi-inverse method for the design of turbomachine blades is presented in this work. Built on a time marching Reynolds-Averaged Navier-Stokes solver, the inverse scheme is capable of designing axial/radial turbomachinery blades in flow regimes ranging from very low Mach number to transonic/supersonic flows. In order to solve flow at all-speed conditions, the preconditioning technique is incorporated into the basic JST time-marching scheme. The accuracy of the resulting flow solver is verified with documented experimental data and commercial CFD codes. The level of accuracy of the flow solver exhibited in those verification cases is typical of CFD analysis employed in the design process in industry. The inverse method described in the present work takes pressure loading and blade thickness as prescribed quantities and computes the corresponding three-dimensional blade camber surface. In order to have the option of imposing geometrical constraints on the designed blade shapes, a new inverse algorithm is developed to solve the camber surface at specified spanwise pseudo stream-tubes (i.e. along grid lines), while the blade geometry is constructed through ruling (e.g. straight-line element) at the remaining spanwise stations. The new inverse algorithm involves re-formulating the boundary condition on the blade surfaces as a hybrid inverse/analysis boundary condition, preserving the full three-dimensional nature of the flow. The new design procedure can be interpreted as a fully three-dimensional viscous semi-inverse method. The ruled surface design ensures the blade surface smoothness and mechanical integrity as well as achieves cost reduction for the manufacturing process. A numerical target shooting experiment for a mixed flow impeller shows that the semi-inverse method is able to accurately recover the target blade composed of straightline element from a different initial blade. The semi-inverse method is proved to work well with various loading strategies for the mixed flow impeller. It is demonstrated that uniformity of impeller exit flow and performance gain can be achieved with appropriate loading combinations at hub and shroud. An application of this semi-inverse method is also demonstrated through a redesign of an industrial shrouded subsonic centrifugal impeller. The redesigned impeller shows improved performance and operating range from the original one. Preliminary studies of blade designs presented in this work show that through the choice of the prescribed pressure loading profiles, this semi-inverse method can be used to design blade with the following objectives: (1) Various operating envelope. (2) Uniformity of impeller exit flow. (3) Overall performance improvement. By designing blade geometry with the proposed semi-inverse method whereby the blade pressure loading is specified instead of the conventional design approach of manually adjusting the blade angle to achieve blade design objectives, designers can discover blade geometry design space that has not been explored before.

  11. Preliminary validation of a new magnetic wireless blood pump.

    PubMed

    Kim, Sung Hoon; Ishiyama, Kazushi; Hashi, Shuichiro; Shiraishi, Yasuyuki; Hayatsu, Yukihiro; Akiyama, Masatoshi; Saiki, Yoshikatsu; Yambe, Tomoyuki

    2013-10-01

    In general, a blood pump must be small, have a simple configuration, and have sufficient hydrodynamic performance. Herein, we introduce new mechanisms for a wireless blood pump that is small and simple and provides wireless and battery-free operation. To achieve wireless and battery-free operation, we implement magnetic torque and force control methods that use two external drivers: an external coil and a permanent magnet with a DC-motor, respectively. Power harvesting can be used to drive an electronic circuit for wireless monitoring (the observation of the pump conditions and temperature) without the use of an internal battery. The power harvesting will be used as a power source to drive other electronic devices, such as various biosensors with their driving circuits. To have both a compact size and sufficient pumping capability, the fully magnetic impeller has five stages and each stage includes four backward-curved blades. The pump has total and inner volumes of 20 and 9.8?cc, respectively, and weighs 52?g. The pump produces a flow rate of approximately 8?L/min at 80?mm?Hg and the power generator produces 0.3?W of electrical power at 120??. The pump also produces a minimum flow rate of 1.5?L/min and a pressure of 30?mm?Hg for circulation at a maximum distance of 7.5?cm. PMID:23634711

  12. Research for the Fluid Field of the Centrifugal Compressor Impeller in Accelerating Startup

    NASA Astrophysics Data System (ADS)

    Li, Xiaozhu; Chen, Gang; Zhu, Changyun; Qin, Guoliang

    2013-03-01

    In order to study the flow field in the impeller in the accelerating start-up process of centrifugal compressor, the 3-D and 1-D transient accelerated flow governing equations along streamline in the impeller of the centrifugal compressor are derived in detail, the assumption of pressure gradient distribution is presented, and the solving method for 1-D transient accelerating flow field is given based on the assumption. The solving method is achieved by programming and the computing result is obtained. It is obtained by comparison that the computing method is met with the test result. So the feasibility and effectiveness for solving accelerating start-up problem of centrifugal compressor by the solving method in this paper is proven.

  13. Effect of impeller geometry on gas-liquid mass transfer coefficients in filamentous suspensions.

    PubMed

    Dronawat, S N; Svihla, C K; Hanley, T R

    1997-01-01

    Volumetric gas-liquid mass transfer coefficients were measured in suspensions of cellulose fibers with concentrations ranging from 0 to 20 g/L. The mass transfer coefficients were measured using the dynamic method. Results are presented for three different combinations of impellers at a variety of gassing rates and agitation speeds. Rheological properties of the cellulose fibers were also measured using the impeller viscometer method. Tests were conducted in a 20 L stirred-tank fermentor and in 65 L tank with a height to diameter ratio of 3:1. Power consumption was measured in both vessels. At low agitation rates, two Rushton turbines gave 20% better performance than the Rushton and hydrofoil combination and 40% better performance than the Rushton and propeller combination for oxygen transfer. At higher agitation rates, the Rushton and hydrofoil combination gave 14 and 25% better performance for oxygen transfer than two Rushton turbines and the Rushton and hydrofoil combination, respectively. PMID:18576095

  14. Computational fluid dynamics modeling of gas dispersion in multi impeller bioreactor.

    PubMed

    Ahmed, Syed Ubaid; Ranganathan, Panneerselvam; Pandey, Ashok; Sivaraman, Savithri

    2010-06-01

    In the present study, experiments have been carried out to identify various flow regimes in a dual Rushton turbines stirred bioreactor for different gas flow rates and impeller speeds. The hydrodynamic parameters like fractional gas hold-up, power consumption and mixing time have been measured. A two fluid model along with MUSIG model to handle polydispersed gas flow has been implemented to predict the various flow regimes and hydrodynamic parameters in the dual turbines stirred bioreactor. The computational model has been mapped on commercial solver ANSYS CFX. The flow regimes predicted by numerical simulations are validated with the experimental results. The present model has successfully captured the flow regimes as observed during experiments. The measured gross flow characteristics like fractional gas hold-up, and mixing time have been compared with numerical simulations. Also the effect of gas flow rate and impeller speed on gas hold-up and power consumption have been investigated. PMID:20471599

  15. Design and performance of family of diffusing scrolls with mixed-flow impeller and vaneless diffuser

    NASA Technical Reports Server (NTRS)

    Brown, W Byron; Bradshaw, Guy R

    1949-01-01

    A family of diffusing scrolls was designed for use with a mixed-flow impeller and a small-diameter vaneless diffuser. The design theory, intended to maintain a uniform pressure around the scroll inlet, permits determination of the position of scroll cross sections of preassigned area by considering the radial variation in fluid density and the effects of friction along the scroll. Inasmuch as the design method leaves the cross-sectional shape undetermined, the effect of certain variations in scroll shape was investigated by studying scrolls having angles of divergence (of the scroll walls downstream of the entrance section) of 24 degrees, 40 degrees, and 80 degrees. A second 80 degree scroll was of asymmetrical construction and a third was plaster-cast instead of sand-cast. Each scroll was tested as a compressor component at actual impeller tip speeds of 700 to 1300 feet per second from full throttle to surge.

  16. Viscous flow during salt welding

    NASA Astrophysics Data System (ADS)

    Wagner, Bryce H.; Jackson, Martin P. A.

    2011-10-01

    Salt can be partially removed by viscous flow from between wall rocks to form a salt weld. Welds in autochthonous and allochthonous salt can form significant structures in evaporite basins, where petroleum and mineral discovery can hinge on whether salt welds act as seals or windows for migrating hydrocarbons or brines containing dissolved metals. Despite the importance of welds, little is known about salt evacuation during welding. We investigate viscous flow during welding using analytical and numerical models, based on exact solutions to the Navier-Stokes equations for idealized geometries and boundary conditions. We explore two questions: how does salt thin during evacuation, and what are the limits of viscous flow during salt welding? Hydraulic-gradient and displacement boundary conditions are shown to drive salt evacuation, which is rate-limited by drag along the boundaries of a salt layer. Where salt flow is restricted, for example beneath a broad, prograding sediment wedge, up to ~ 50 m salt can remain in an incomplete weld. Where salt flow is unrestricted, for example beneath a subsiding minibasin, viscous flow can remove all but a vanishingly thin (<<1 m) salt layer. In both cases, any remaining salt must be dissolved to leave a weld containing no remnant salt. Evacuation rate increases with increasing differential stress and decreasing flow length and dynamic viscosity of the salt. Translation of wall rock parallel to bedding may result in a fault weld but may also inhibit evacuation if the displacement counteracts flow driven by a hydraulic gradient. Evacuation of multilayered evaporites is controlled by the distribution of layer thickness and viscosity. Multilayered evaporites can be compositionally modified during evacuation.

  17. Creep Property Characterization of Potential Brayton Cycle Impeller and Duct Materials

    Microsoft Academic Search

    Timothy P. Gabb; John Gayda; Anita Garg

    2007-01-01

    Cast superalloys have potential applications in space as impellers within closed-loop Brayton cycle nuclear power generation systems. Likewise wrought superalloys are good candidates for ducts and heat exchangers transporting the inert working gas in a Brayton-based power plant. Two cast superalloys, Mar-M247LC and IN792, and a NASA GRC powder metallurgy superalloy, LSHR, have been screened to compare their respective capabilities

  18. Experimental Impeller Fragmentation of Iliocaval Thrombosis Under Tulip Filter Protection: Preliminary Results

    SciTech Connect

    Schmitz-Rode, Thomas; Vorwerk, Dierk; Schuermann, Karl; Guenther, Rolf W. [Department of Diagnostic Radiology, University of Technology, Klinikum Aachen, Pauwelsstrasse 30, D-52057 Aachen (Germany)

    1996-04-15

    Purpose: To assess the efficacy of catheter fragmentation of massive caval thrombosis and of filter protection against procedure-related pulmonary embolism. Methods: In 10 sheep, a self-expanding tulip-shaped filter made from Wallstent mesh (diameter 25 mm) was introduced from the right jugular approach into the proximal inferior vena cava. Experimentally induced massive iliocaval thrombosis was fragmented by an impeller catheter (expanded diameter 14 mm), which was advanced coaxially through the sheath of the expanded filter. Post-procedural cavography and pulmonary angiography were performed to document the extent of caval recanalization and pulmonary embolism. Results: In all cases, impeller fragmentation cleared the inferior vena cava and the iliac veins of thrombi completely. Fragments washed downstream were trapped in the filter. In two of the first cases, parts of the clots caused pulmonary embolism before the filter was in place. Further events were avoided by a modification of the experimental setup. Except for some small peripheral perfusion defects in two cases, pulmonary angiograms did not show any incidence of pulmonary embolism. Conclusion: Our preliminary results suggest that impeller fragmentation of iliocaval thrombi under tulip filter protection is effective and does not cause significant pulmonary embolism.

  19. Using a Breast Pump

    MedlinePLUS

    ... Devices Consumer Products Breast Pumps Using a Breast Pump Before using your breast pump for the first ... pump movie ) General Tips for Using a Breast Pump Wash and Dry Your Hands Before using your ...

  20. Single stage high pressure centrifugal slurry pump

    DOEpatents

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

    1984-03-27

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

  1. Electromagnetic pump

    NASA Astrophysics Data System (ADS)

    Bonin, Richard L.

    1994-02-01

    A pump having a stator that forms a cylindrical chamber defined by a wall and a plurality of independently energizable magnetic field generators. A compression roller comprising a magnetic material is disposed within the wall and is free to move with respect to the stator. A flexible diaphragm is intermediate the stator and the compression roller and disposed along the wall portion. The flexible diaphragm to be pumped has an input port and an outlet port for the fluid being pumped. An energizing control at any given instant energizes a plurality of adjacent ones of the magnetic field generators. The magnetic field generators are organized into overlapping sets that can be energized as sets in sequence thereby to produce a rotating, axially extending magnetic field within the wall. The compression roller follows the rotating field thereby to compress adjacent positions of the flexible diaphragm to pump fluid from the diaphragm through the inlet port to the outlet port.

  2. Electrokinetic pump

    DOEpatents

    Patel, Kamlesh D. (Dublin, CA)

    2007-11-20

    A method for altering the surface properties of a particle bed. In application, the method pertains particularly to an electrokinetic pump configuration where nanoparticles are bonded to the surface of the stationary phase to alter the surface properties of the stationary phase including the surface area and/or the zeta potential and thus improve the efficiency and operating range of these pumps. By functionalizing the nanoparticles to change the zeta potential the electrokinetic pump is rendered capable of operating with working fluids having pH values that can range from 2-10 generally and acidic working fluids in particular. For applications in which the pump is intended to handle highly acidic solutions latex nanoparticles that are quaternary amine functionalized can be used.

  3. Enhancement of hemocompatibility of the MERA monopivot centrifugal pump: toward medium-term use.

    PubMed

    Yamane, Takashi; Kosaka, Ryo; Nishida, Masahiro; Maruyama, Osamu; Yamamoto, Yoshihiro; Kuwana, Katsuyuki; Kawamura, Hiroshi; Shiraishi, Yasuyuki; Yambe, Tomoyuki; Sankai, Yoshiyuki; Tsutsui, Tatsuo

    2013-02-01

    The MERA monopivot centrifugal pump has been developed for use in open-heart surgery, circulatory support, and bridge-to-decision for up to 4?weeks. The pump has a closed-type, 50-mm diameter impeller with four straight paths. The impeller is supported by a monopivot bearing and is driven by a radial-flux magnet-coupling motor. Because flow visualization experiments have clarified sufficient pivot wash and stagnation at the sharp corner of the pivot support was suggested, sharp corners were removed in the design stage. The index of hemolysis of the pump operating at more than 200?mm?Hg was found to be lower than that of a commercial pump. Four-week animal tests were then conducted two times; improvement of thrombus formation was seen in the female pivot through modification of female pivot geometry. Overall antithrombogenicity was also recorded. Finally, to assure mid-term use, an additional 4-week durability test revealed that the rate of the axial pivot wear was as small as 1.1?µm/day. The present in vitro and in vivo studies revealed that the MERA monopivot centrifugal pump has sufficient hemocompatibility and durability for up to 4?weeks. PMID:23020805

  4. Relativistic shock waves in viscous gluon matter

    E-print Network

    I. Bouras; E. Molnar; H. Niemi; Z. Xu; A. El; O. Fochler; C. Greiner; D. H. Rischke

    2009-07-22

    We solve the relativistic Riemann problem in viscous gluon matter employing a microscopic parton cascade. We demonstrate the transition from ideal to viscous shock waves by varying the shear viscosity to entropy density ratio $\\eta/s$ from zero to infinity. We show that an $\\eta/s$ ratio larger than 0.2 prevents the development of well-defined shock waves on timescales typical for ultrarelativistic heavy-ion collisions. Comparisons with viscous hydrodynamic calculations confirm our findings.

  5. Relativistic Shock Waves in Viscous Gluon Matter

    SciTech Connect

    Bouras, I.; Xu, Z.; El, A.; Fochler, O.; Greiner, C. [Institut fuer Theoretische Physik, Johann Wolfgang Goethe-Universitaet, Max-von-Laue-Strasse 1, D-60438 Frankfurt am Main (Germany); Molnar, E.; Niemi, H. [Frankfurt Institute for Advanced Studies, Ruth-Moufang-Strasse 1, D-60438 Frankfurt am Main (Germany); Rischke, D. H. [Institut fuer Theoretische Physik, Johann Wolfgang Goethe-Universitaet, Max-von-Laue-Strasse 1, D-60438 Frankfurt am Main (Germany); Frankfurt Institute for Advanced Studies, Ruth-Moufang-Strasse 1, D-60438 Frankfurt am Main (Germany)

    2009-07-17

    We solve the relativistic Riemann problem in viscous gluon matter employing a microscopic parton cascade. We demonstrate the transition from ideal to viscous shock waves by varying the shear viscosity to entropy density ratio eta/s from zero to infinity. We show that an eta/s ratio larger than 0.2 prevents the development of well-defined shock waves on time scales typical for ultrarelativistic heavy-ion collisions. Comparisons with viscous hydrodynamic calculations confirm our findings.

  6. The study of a reactor cooling pump under two-phase flow

    NASA Astrophysics Data System (ADS)

    Wang, P.; Yuan, S. Q.; Wang, X. L.; Zhang, F.

    2015-01-01

    In this paper, the steady pressure field has been investigated numerically by computational fluid dynamics (CFD) in a nuclear reactor cooling pump. As a multiphase approach the Eulerian-Eulerian two fluid model has been applied to calculated five computational models with different kinds of blades. The analysis of inner flow field of the five model pumps shows that the pressure in the impeller increases with the increase of the gas contents and the pressure distributions are irregular at the inlet of different blades when the gas contents less than 20%. With the increase of the number of blades, the vortexes at the outlet of impeller decrease whereas the vortexes in the deep of the volute markedly increases and high velocity of the fluid huddle is generated gradually at the outlet pipes. Under the action of centrifugal force and Coriolis force, gas phase mainly concentrated at the lower velocity and lower pressure area. The radial force on the impeller gradually increases with the increase of the gas contents.

  7. Viscous fluid interpretation of some exact solutions

    SciTech Connect

    Carot, J.; Ibanez, J.

    1985-09-01

    An example of the equivalence between a perfect fluid and a viscous fluid is presented, showing that the Schwarzschild interior solution obtained from a perfect fluid can also be derived from a viscous fluid with heat conduction. The equivalence between a scalar field and a viscous fluid is investigated, showing that under certain circumstances, both can generate, from Einstein's equations, the same space-time geometry. Some examples are presented and, in particular, it is shown that every plane-symmetric solution deduced from a scalar field can also be derived from a viscous fluid.

  8. Fluctuating pressures in pump diffuser and collector scrolls, part 1

    NASA Technical Reports Server (NTRS)

    Sloteman, Donald P.

    1989-01-01

    The cracking of scroll liners on the SSME High Pressure Fuel Turbo Pump (HPFTP) on hot gas engine test firings has prompted a study into the nature of pressure fluctuations in centrifugal pump states. The amplitudes of these fluctuations and where they originate in the pump stage are quantified. To accomplish this, a test program was conducted to map the pressure pulsation activity in a centrifugal pump stage. This stage is based on typical commercial (or generic) pump design practice and not the specialized design of the HPFTP. Measurements made in the various elements comprising the stage indicate that pulsation activity is dominated by synchronous related phenomena. Pulsation amplitudes measured in the scroll are low, on the order of 2 to 7 percent of the impeller exit tip speed velocity head. Significant non-sychronous pressure fluctuations occur at low flow, and while of interest to commercial pump designers, have little meaning to the HPFTP experience. Results obtained with the generic components do provide insights into possible pulsation related scroll failures on the HPFTP, and provide a basis for further study.

  9. Optimal Tracing of Viscous Shocks in Solutions of Viscous Conservation Laws

    Microsoft Academic Search

    Wen Shen; Mee Rea Park

    2006-01-01

    This paper contains a qualitative study of a scalar conservation law with viscosity: ut + f (u)x = uxx . We consider the problem of identifying the location of viscous shocks, thus obtaining an optimal finite dimensional description of solutions to the viscous conservation law. We introduce a nonlinear functional whose minimizers yield the viscous traveling profiles which optimally fit

  10. Computation Of Steady and Unsteady Viscous Flows Using a Simultaneously Coupled Inviscid-Viscous Interaction Technique

    Microsoft Academic Search

    P. G. A. Cizmas; K. C. Hall

    1995-01-01

    An interacting viscous-inviscid method for efficiently computing steady and unsteady low Mach number viscous flows with separation is presented. The inviscid region is modeled using a finite element discretization of the full potential equation. The viscous region is modeled using a finite difference boundary layer technique. The two regions are simultaneously coupled through the requirement that the edge velocities of

  11. Inhomogeneous viscous fluids for inflation

    E-print Network

    Ratbay Myrzakulov; Lorenzo Sebastiani

    2014-11-18

    In this paper, we investigate inhomogeneous viscous fluid cosmology for inflation. Several toy models are presented in the attempt to analyze how inflation can be realized according with cosmological data by making use of an inhomogeneous EoS parameter for the fluid and/or by introducing a viscosity to have a graceful exit from inflation. The results will be compared with the ones of scalar field representation and discussed. We will pay attention on the possibility to recover the reheating and therefore the Friedmann universe.

  12. Gastrostomy feeding tube - pump

    MedlinePLUS

    Feeding - gastrostomy tube - pump; G-tube - pump; Gastrostomy button - pump; Bard Button - pump; MIC-KEY - pump ... Gather supplies: Feeding pump (electronic or battery powered) Feeding set that matches the feeding pump (includes a feeding bag, drip chamber, roller clamp, ...

  13. A finite element viscous flow analysis in a radial turbine scroll 

    E-print Network

    Hill, Donald Lee

    1987-01-01

    turbomachinery components. This category includes such components as centrifugal compressor snd pump volutes which are principally similar in shape to radial turbine scrolls. The numerical results obtained using this newly developed procedure indicated...A FINITE ELEMENT VISCOUS FLOW ANALYSIS IN A RADIAL TURBINE SCROLL A Thesis DONALD LEE HILL JR. Submitted to the Graduate College. of Texas ASM University in partial fulfillment of the requirement for the degree of MASTER OF SCIENCE December...

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

    NASA Astrophysics Data System (ADS)

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

    2012-11-01

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

  15. The comparative performance of Roots type aircraft engine superchargers as affected by change in impeller speed and displacement

    NASA Technical Reports Server (NTRS)

    Ware, Marsden; Wilson, Ernest E

    1929-01-01

    This report presents the results of tests made on three sizes of roots type aircraft engine superchargers. The impeller contours and diameters of these machines were the same, but the length were 11, 8 1/4, and 4 inches, giving displacements of 0.509, 0.382, and 0.185 cubic foot per impeller revolution. The information obtained serves as a basis for the examination of the individual effects of impeller speed and displacement on performance and of the comparative performance when speed and displacement are altered simultaneously to meet definite service requirements. According to simple theory, when assuming no losses, the air weight handled and the power required for a given pressure difference are directly proportional to the speed and the displacement. These simple relations are altered considerably by the losses. When comparing the performance of different sizes of machines whose impeller speeds are so related that the same service requirements are met, it is found that the individual effects of speed and displacement are canceled to a large extent, and the only considerable difference is the difference in the power losses which decrease with increase in the displacement and the accompanying decrease in speed. This difference is small in relation to the net power of the engine supercharger unit, so that a supercharger with short impellers may be used in those applications where the space available is very limited with any considerable sacrifice in performance.

  16. Viscous-pendulum damper suppresses structural vibrations

    NASA Technical Reports Server (NTRS)

    Reed, W. H., III

    1964-01-01

    The viscous pendulum damper consists of a cylinder containing round trays on which round lead slugs rest. When assembled, the container is filled with a viscous liquid and attached, with axis vertical, to the structure. The device permits varying the damping of structural vibrations.

  17. Performance of J33-A-23 Turbojet-Engine Compressor. II; Over-All Performance Characteristics of Compressor with 34-Blade Impeller at Equivalent Impeller Speeds from 6000 to 11.750 RPM

    NASA Technical Reports Server (NTRS)

    Beede, William L.; Kovach, Karl

    1948-01-01

    The J33-A-23 compressor with a 34-blade impeller was operated at ambient inlet temperature and an inlet pressure of 14 inches mercury absolute over a range of equivalent impeller speeds from 6000 to 11,750 rpm. Additional runs at equivalent speeds of 7,000, 10,000, and 11,750 rpm and ambient inlet temperature were made at inlet pressures of 5 and 10 inches mercury absolute. The results of this investigation are compared with those of the J33-A-23 compressor with a 17-blade impeller. At the design equivalent speed of 11,750 rpm the 533-A-23 compressor with a 34-blade impeller had a peak pressure ratio of 4.49 at an equivalent weight flow of 82.4 pounds per second and an adiabatic temperature-rise efficiency of 0.740. The maximum equivalent flow at design speed was 91.8 pounds per second. The peak efficiency at design speed (0.757) occurred at an equivalent weight flow of 85.5 pounds per second. The maximum adiabatic temperature- rise efficiency of 0.773 was obtained at an equivalent impeller speed of 10,000 rpm, an equivalent weight flow of 65.8 pounds per second, and a pressure ratio of 3.27. At equivalent impeller speeds of.l0,000 and 11,75O rpm a decrease in inlet pressure resulted in a decrease in maximum equivalent weight flow, peak pressure ratio, and peak adiabatic temperature- rise efficiency.

  18. Pump jack

    SciTech Connect

    Stanton, G. E.

    1985-02-26

    A pump jack of the type comprising a rocker arm pivotably mounted intermediate its ends on a support member, said rocker arm being divided by said pivot mounting into a sucker-rod limb and a drive limb wherein the improvement comprises a pneumatic motor pivotably attached to the drive support member and further pivotably attached to the mounting base of the pump jack to provide the power to reciprocate the pump jack. The working fluid of said pneumatic motor being natural gas which is available from the well casing of the well without any interference with the flow of the oil in the oil tube of the well thereby making use of an energy source available at any oil well without having to provide gasoline to drive a rotating type gasoline engine or electricity to drive an electric motor usually of the rotating variety. Also the stroke of a pneumatic cylinder inherently smooths out and eliminates the shock loading at the extremes of motion at the piston mounted to the sucker rods of such pump jack at the bottom of the well.

  19. Aerodesign and performance analysis of a radial transonic impeller for a 9:1 pressure ratio compressor

    SciTech Connect

    Colantuoni, S.; Colella, A. (Alfa Romeo Avio, Societa Aeromotoristica p.A., Napoli (Italy). Research and Development)

    1993-07-01

    The aerodynamic design of a centrifugal compressor for technologically advanced small aeroengines requires more and more the use of sophisticated computational tools in order to meet the goals successfully at minimum cost development. The objective of the present work is the description of the procedure adopted to design a transonic impeller having 1.31 relative Mach number at the inducer tip, 45 deg back-swept exit blade angle, and a tip speed of 636 m/s. The optimization of the blade shape has been done by analyzing the aerodynamic flowfield by extensive use of a quasi-three-dimensional code and a fully three-dimensional Euler solver based on a time-marching approach and a finite volume discretization. Testing has been done on the impeller-only configuration, using a compressor rig that simulates real engine hardware, i.e. having an S-shaped air-intake. The overall performance of the impeller is presented and discussed.

  20. 18. Electrically driven pumps in Armory Street Pump House. Pumps ...

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

    18. Electrically driven pumps in Armory Street Pump House. Pumps in background formerly drew water from the clear well. They went out of service when use of the beds was discontinued. Pumps in the foreground provide high pressure water to Hamden. - Lake Whitney Water Filtration Plant, Armory Street Pumphouse, North side of Armory Street between Edgehill Road & Whitney Avenue, Hamden, New Haven County, CT

  1. Study on vibration characteristics of the shaft system for a dredging pump based on FEM

    NASA Astrophysics Data System (ADS)

    Zhai, L. M.; Qin, L.; Liu, C. Y.; Liu, X.; He, L. Y.; He, Y.; Wang, Z. W.

    2012-11-01

    The dynamic characteristics of the shaft system for a dredging pump were studied with the Finite Element Method (FEM) by SAMCEF ROTOR. At first, the influence of the fluid-solid coupling interaction of mud water and impeller, water sealing and pump shaft on the lateral critical speeds were analyzed. The results indicated that the mud water must be taken into consideration, while the water sealing need not to. Then the effects of radial and thrust rolling bearings on the lateral critical speeds were discussed, which shows that the radial bearing close to the impeller has greatest impact on the 1st order critical speed. At last, the upper and lower limits of the critical speeds of lateral, axial and torsional vibration were calculated. The rated speed of the dredging pump was far less than the predicted critical speed, which can ensure the safe operation of the unit. Each vibration mode is also shown in this paper. This dynamic analysis method offers some reference value on the research of vibration and stability of the shaft system in dredging pump.

  2. Radiation-viscous boundary layer

    NASA Technical Reports Server (NTRS)

    Arav, Nahum; Begelman, Mitchell C.

    1992-01-01

    A viscous boundary layer (BL) is studied which is most likely to occur in astrophysical systems dominated by radiation pressure, in particular compact objects surrounded by a very optically thick envelope and radiating at close to the Eddington limit. Calculations are reported which show that a BL due to radiation viscosity behaves very differently from a 'classical' incompressible BL for flows with Mach number M much greater than unity far from the BL. In these flows the width of the BL is much larger than its incompressible value and scales as M-squared times the width of the imcompressible BL. The density inside the BL is much lower than that in the undisturbed fluid and scales as 1/M-squared with respect to the value far away from the BL. It is concluded that under certain circumstances a cocoon of low-density material will develop between a jet and its surrounding medium.

  3. Identified particles from viscous hydrodynamics

    NASA Astrophysics Data System (ADS)

    Molnar, Denes

    2011-12-01

    Identified particle observables from viscous hydrodynamics are sensitive to the fluid-to-particle conversion. Instead of the commonly assumed 'democratic' Grad ansatz for phase space corrections ?f, we utilize corrections calculated from linearized covariant transport theory. Estimates based on a ?-p system with binary collisions indicate that protons are much closer to equilibrium than pions, significantly affecting the dissipative reduction of differential elliptic flow in Au+Au at the RHIC. In addition, we test the linear response against fully nonlinear transport for a two-component massless system in a Bjorken scenario. Strikingly, we find that, while linear response accounts well for the dynamical sharing of shear stress, the momentum dependence of phase space corrections is best described by Grad's quadratic ansatz, and not the linear response solution.

  4. Computational Approach for Developing Blood Pump

    NASA Technical Reports Server (NTRS)

    Kwak, Dochan

    2002-01-01

    This viewgraph presentation provides an overview of the computational approach to developing a ventricular assist device (VAD) which utilizes NASA aerospace technology. The VAD is used as a temporary support to sick ventricles for those who suffer from late stage congestive heart failure (CHF). The need for donor hearts is much greater than their availability, and the VAD is seen as a bridge-to-transplant. The computational issues confronting the design of a more advanced, reliable VAD include the modelling of viscous incompressible flow. A computational approach provides the possibility of quantifying the flow characteristics, which is especially valuable for analyzing compact design with highly sensitive operating conditions. Computational fluid dynamics (CFD) and rocket engine technology has been applied to modify the design of a VAD which enabled human transplantation. The computing requirement for this project is still large, however, and the unsteady analysis of the entire system from natural heart to aorta involves several hundred revolutions of the impeller. Further study is needed to assess the impact of mechanical VADs on the human body

  5. Demonstration of a Low-Lift Heat Pump for High-Power Spacecraft Thermal Control

    NASA Astrophysics Data System (ADS)

    Grzyll, Lawrence R.

    2006-01-01

    This paper describes the development and demonstration of a prototype low-lift heat pump for high-power spacecraft thermal control The low-lift heat pump was designed to provide 25 kW of cooling at 303 K and transport this waste heat to a radiator for heat rejection. To accomplish this, a demonstration heat pump with an evaporation temperature of 298 K and a condensing temperature of 301 K was designed and built. HFC-227ea was the working fluid. This effort resulted in optimization of the centrifugal compressor impeller, diffuser, and shroud designs through extensive experimental testing. The detailed design of a magnetic bearing centrifugal compressor was completed. A prototype heat pump thermal control system was designed and fabricated which contained prototypical cold plate and condenser designs. This prototype system was extensively tested and demonstrated to measure performance parameters such as power consumption, cooling capacity, system size and mass, and other key parameters. Finally, the experimental performance was input into the theoretical trade study allowing for a comparison of the actual performance of the low-lift heat pump to a single-phase pumped loop. Inputting the experimental low-lift heat pump performance into the trade study showed that the low-lift heat pump still has lower system mass than the single-phase pumped loop for all space temperatures considered. The experimental results very closely match the theoretical results used in the trade study.

  6. Numerical investigation of solid-liquid two phase flow in a non-clogging centrifugal pump at off-design conditions

    NASA Astrophysics Data System (ADS)

    Zhao, B. J.; Huang, Z. F.; Chen, H. L.; Hou, D. H.

    2012-11-01

    The solid-liquid two-phase flow fields in the non-clogging centrifugal pump with a double-channel impeller have been investigated numerically for the design condition and also off-design conditions, in order to study the solid-liquid two-phase flow pattern and non-clogging mechanism in non-clogging centrifugal pumps. The main conclusions include: The sand volume fraction distribution is extremely inhomogeneous in the whole flow channel of the pump at off-design conditions. In the impeller, particles mainly flow along the pressure surface and hub; In the volute, particles mainly accumulate in the region near to the exit of volute, the largest sand volume fraction is observed at the tongue, and a large number of particles collide with volute wall and exit the volute after circling around the volute for several times. When the particle diameter increases, particles tend to accumulate on the pressure side of the impeller, and more particles crash with the pressure side of the blade. And larger sand volume fraction gratitude is also observed in the whole flow channel of the pump. With the decrease of the inlet sand volume fraction, particles tend to accumulate on the suction side of the blade. Compared with the particle diameter, the inlet sand volume fraction has less influence on the sand volume fraction gratitude in the whole channel of the pump. At the large flow rate, the minimum and maximum sand volume fraction in the whole flow channel of the model pump tends to be smaller than that at the small flow rate. Thus, it is concluded that the water transportation capacity increases with the flow rate. This research will strengthen people's understanding of the multiphase flow pattern in non-clogging centrifugal pumps, thus provides a theoretical basis for the optimal design of non-clogging centrifugal pumps.

  7. Role of Soft-Iron Impellers on the Mode Selection in the von Karman-Sodium Dynamo Experiment

    SciTech Connect

    Giesecke, Andre; Stefani, Frank; Gerbeth, Gunter [Forschungszentrum Dresden-Rossendorf, P.O. Box 510119, D-01314 Dresden (Germany)

    2010-01-29

    A crucial point for the understanding of the von Karman-sodium (VKS) dynamo experiment is the influence of soft-iron impellers. We present numerical simulations of a VKS-like dynamo with a localized permeability distribution that resembles the shape of the flow driving impellers. It is shown that the presence of soft-iron material essentially determines the dynamo process in the VKS experiment. An axisymmetric magnetic field mode can be explained by the combined action of the soft-iron disk and a rather small {alpha} effect parametrizing the induction effects of unresolved small scale flow fluctuations.

  8. Heat pumps. Second edition

    Microsoft Academic Search

    D. A. Reay; D. B. A. Mac Michael

    1986-01-01

    This book provides a revised and extended account of the design, manufacture and use of heat pumps in industrial and domestic applications. Topics covered include the following: history of the heat pump; heat pump theory; practical design; design problem areas; heat pump applications domestic; heat pumps in commercial and municipal buildings; and heat pump applications in industry.

  9. Comparison of velocity-log data collected using impeller and electromagnetic flowmeters

    USGS Publications Warehouse

    Newhouse, M.W.; Izbicki, J.A.; Smith, G.A.

    2005-01-01

    Previous studies have used flowmeters in environments that are within the expectations of their published ranges. Electromagnetic flowmeters have a published range from 0.1 to 79.0 m/min, and impeller flowmeters have a published range from 1.2 to 61.0 m/min. Velocity-log data collected in five long-screened production wells in the Pleasant Valley area of southern California showed that (1) electromagnetic flowmeter results were comparable within ??2% to results obtained using an impeller flowmeter for comparable depths; (2) the measured velocities from the electromagnetic flowmeter were up to 36% greater than the published maximum range; and (3) both data sets, collected without the use of centralizers or flow diverters, produced comparable and interpretable results. Although either method is acceptable for measuring wellbore velocities and the distribution of flow, the electromagnetic flowmeter enables collection of data over a now greater range of flows. In addition, changes in fluid temperature and fluid resistivity, collected as part of the electromagnetic flowmeter log, are useful in the identification of flow and hydrogeologic interpretation.

  10. Computer Aided Simulation Machining Programming In 5-Axis Nc Milling Of Impeller Leaf

    NASA Astrophysics Data System (ADS)

    Huran, Liu

    At present, cad/cam (computer-aided design and manufacture) have fine wider and wider application in mechanical industry. For the complex surfaces, the traditional machine tool can no longer satisfy the requirement of such complex task. Only by the help of cad/cam can fulfill the requirement. The machining of the vane surface of the impeller leaf has been considered as the hardest challenge. Because of their complex shape, the 5-axis cnc machine tool is needed for the machining of such parts. The material is hard to cut, the requirement for the surface finish and clearance is very high, so that the manufacture quality of impeller leaf represent the level of 5-axis machining. This paper opened a new field in machining the complicated surface, based on a relatively more rigid mathematical basis. The theory presented here is relatively more systematical. Since the lack of theoretical guidance, in the former research, people have to try in machining many times. Such case will be changed. The movement of the cutter determined by this method is definite, and the residual is the smallest while the times of travel is the fewest. The criterion is simple and the calculation is easy.

  11. Effect of impeller geometry on gas-liquid mass transfer coefficients in filamentous suspensions

    SciTech Connect

    Dronawat, S.N.; Svihla, C.K.; Hanley, T.R. [Univ. of Louisville, KY (United States)

    1997-12-31

    Volumetric gas-liquid mass transfer coefficients were measured in suspensions of cellulose fibers with concentrations ranging from 0 to 20 g/L. The mass transfer coefficients were measured using the dynamic method. Results are presented for three different combinations of impellers at a variety of gassing rates and agitation speeds. Rheological properties of the cellulose fibers were also measured using the impeller viscometer method. Tests were conducted in a 20 L stirred-tank fermentor and in 65 L tank with a height to diameter ratio of 3:1. Power consumption was measured in both vessels. At low agitation rates, two Rushton turbines gave 20% better performance than the Rushton and hydrofoil combination and 40% better performance than the Rushton and propeller combination for oxygen transfer. At higher agitation rates, the Rushton and hydrofoil combination gave 14 and 25% better performance for oxygen transfer than two Rushton turbines and the Rushton and hydrofoil combination, respectively. 8 refs., 11 figs., 1 tab.

  12. An analysis of flow in a centrifugal impeller by FEM with k-? model

    NASA Astrophysics Data System (ADS)

    Matsumoto, Satoshi; Ohba, Hideki; Miyamoto, Hiroyuki

    2001-03-01

    In this study, we attempt the analysis of the passage flow in the centrifugal impeller using FEM with/without the turbulence model, and compare this result with the experimental result. The turbulence model is the low Reynolds k-? model proposed by Chien. We use the GSMAC method for the Reynolds averaged Navier-Stokes equations, the Euler explicit method for the transport equations of the turbulent kinetic energy and the dissipation rate. All equations are discretized by the Galerkin’s method. At the midpassage of the centrifugal impeller, the passagewise velocity component tends to increase in the pressure-to-suction direction, and the other component toward the pressure surface tends to be large in the region of the middle blade-to-blade to the hub side. The tip leakages appear around the region of the middle blade-to-blade near the casing together with the secondary flow toward the suction surface. These phenomena correspond with the experimental result, qualitatively.

  13. Creep Property Characterization of Potential Brayton Cycle Impeller and Duct Materials

    NASA Astrophysics Data System (ADS)

    Gabb, Timothy P.; Gayda, John; Garg, Anita

    2007-01-01

    Cast superalloys have potential applications in space as impellers within closed-loop Brayton cycle nuclear power generation systems. Likewise wrought superalloys are good candidates for ducts and heat exchangers transporting the inert working gas in a Brayton-based power plant. Two cast superalloys, Mar-M247LC and IN792, and a NASA GRC powder metallurgy superalloy, LSHR, have been screened to compare their respective capabilities for impeller applications. Mar-M247LC has been selected for additional long term evaluations. Initial tests in helium indicate this inert environment may debit long term creep resistance of this alloy. Several wrought superalloys including Hastelloy® X, Inconel® 617, Inconel® 740, Nimonic® 263, Incoloy® MA956, and Haynes 230 are also being screened to compare their capabilities for duct applications. Haynes 230 has been selected for additional long term evaluations. Initial tests in helium are just underway for this alloy. These proposed applications would require sufficient strength and creep resistance for long term service at temperatures up to 1200 K, with service times to 100,000 h or more. Therefore, long term microstructural stability is also being screened.

  14. Inhomogeneous viscous fluid in anisotropic inflationary universe

    NASA Astrophysics Data System (ADS)

    Sharif, M.; Mohsaneen, Sidra

    2015-06-01

    In this paper, we study inhomogeneous viscous fluid for inflation in the framework of locally rotationally symmetric Bianchi type I universe model. We consider an inhomogeneous equation of state with viscosity term to ensure a graceful exit from inflationary period. In order to study inflationary perturbations, we evaluate slow-roll parameters, scalar and tensor power spectra, scalar spectral index, tensor to scalar ratio for scalar field and inhomogeneous viscous fluid. It is concluded that our anisotropic inflationary universe model with inhomogeneous viscous fluid is consistent with recent data in a specific range of the model parameters.

  15. Direct photon production from viscous QGP

    Microsoft Academic Search

    A. K. Chaudhuri; Bikash Sinha

    2011-01-01

    We simulate direct photon production in evolution of viscous QGP medium.\\u000aPhotons from Compton and annihilation processes are considered. Viscous effect\\u000aon photon production is very strong and reliable simulation is possible only in\\u000aa limited $p_T$ range. For minimally viscous fluid $\\\\eta\\/s$=0.08), direct\\u000aphotons can be reliably computed only up to $p_T \\\\leq$ 1.3 GeV. With reduced\\u000aviscosity ($\\\\eta\\/s$=0.04),

  16. Evaluation of Failed Crane Chempumps Used During Salt Well Pumping

    SciTech Connect

    ELSEN, J.J.

    2000-09-18

    The Interim Stabilization Project is responsible for removing pumpable interstitial liquid from remaining single shelled tanks and transferring the waste to safer double-shelled tanks. This waste transfer is conducted by installing a saltwell pumping system within the designated single shell tank, and transferring the waste to double shelled tank using approved transfer lines. The saltwell pumping system is placed within a saltwell screen installed into the tank waste, the screen is designed to allow gravity flow of liquid into the screen and prevent solids from entering the pumping system. A foot valve consisting of a venturi jet and nozzle creates a suction, picking up waste at an equal rate as the out flow transfer rate of the saltwell system. A centrifugal pump is used to create the motive force across the eductor and drive the waste through the associated system piping and transfer lines leading to the double shelled tanks. The centrifugal pump that has typically been used in the saltwell pumping system installations is the Crane Chempump, model GA-1 1/2 K with 4 3/4 inch impeller. The following evaluation is not intended to be an all inclusive analysis of the operation of a saltwell system and associated pump. This evaluation will detail some of the noted failures in specific saltwell systems and document those findings. Due to the large number of saltwell systems installed over the duration of the Stabilization Project, only those saltwell systems installed over the last two years within S, SX, U, A and AX tank farms, shall be included in this evaluation. After identification of the pump failures mechanism, recommendations shall be identified to address potential means of improving overall operational efficiency and reducing overall equipment failures.

  17. A new model of centrifugal blood pump for cardiopulmonary bypass: design improvement, performance, and hemolysis tests.

    PubMed

    Leme, Juliana; Fonseca, Jeison; Bock, Eduardo; da Silva, Cibele; da Silva, Bruno Utiyama; Dos Santos, Alex Eugênio; Dinkhuysen, Jarbas; Andrade, Aron; Biscegli, José F

    2011-05-01

    A new model of blood pump for cardiopulmonary bypass (CPB) application has been developed and evaluated in our laboratories. Inside the pump housing is a spiral impeller that is conically shaped and has threads on its surface. Worm gears provide an axial motion of the blood column. Rotational motion of the conical shape generates a centrifugal pumping effect and improves pumping performance. One annular magnet with six poles is inside the impeller, providing magnetic coupling to a brushless direct current motor. In order to study the pumping performance, a mock loop system was assembled. Mock loop was composed of Tygon tubes (Saint-Gobain Corporation, Courbevoie, France), oxygenator, digital flowmeter, pressure monitor, electronic driver, and adjustable clamp for flow control. Experiments were performed on six prototypes with small differences in their design. Each prototype was tested and flow and pressure data were obtained for rotational speed of 1000, 1500, 2000, 2500, and 3000 rpm. Hemolysis was studied using pumps with different internal gap sizes (1.35, 1.45, 1.55, and 1.7 mm). Hemolysis tests simulated CPB application with flow rate of 5 L/min against total pressure head of 350 mm Hg. The results from six prototypes were satisfactory, compared to the results from the literature. However, prototype #6 showed the best results. Best hemolysis results were observed with a gap of 1.45 mm, and showed a normalized index of hemolysis of 0.013 g/100 L. When combined, axial and centrifugal pumping principles produce better hydrodynamic performance without increasing hemolysis. PMID:21595709

  18. Computational fluid dynamics analysis of the pump parameters in the helical flow pump.

    PubMed

    Hosoda, Kyohei; Ishii, Kohei; Isoyama, Takashi; Saito, Itsuro; Inoue, Yusuke; Ariyoshi, Kouki; Ono, Toshiya; Nakagawa, Hidemoto; Imachi, Kou; Kumagai, Hiroshi; Abe, Yusuke

    2014-03-01

    The helical flow pump (HFP) was invented to develop a total artificial heart at the University of Tokyo in 2005. The HFP consists of the multi-vane impeller involving rotor magnets, a motor stator and pump housing having double-helical volutes. To investigate the characteristics of the HFP, computational fluid dynamics analysis was performed. Validation of the computational model was performed with the data of the actual pump. A control computational model in which the vane area corresponded approximately to that of the actual pump was designed for the parametric study. The parametric study was performed varying the vane height, vane width and helical volute pitch. When the vane height was varied from 0.5 to 1.5 times that of the control computational model, the H-Q (pressure head vs. flow) and efficiency curves were translated in parallel with the vane height. When the vane height was two and three times that of the control computational model, the profile of these curves changed. From the results, the best proportion for the vane was considered to be a vane height between 1.5 and 2 times the vane width. The effect of vane width was not very strong compared to that of the vane height. A similar tendency in vane height was observed by varying the helical volute pitch. The best helical volute-pitch size is considered to be between 1.5 and 2 times the vane width. Although further study is necessary to determine the best values for these parameters, the characteristics of the pump parameters in the HFP could be approximately clarified. PMID:24318404

  19. Nonlinear Stability of Viscous Roll Waves

    E-print Network

    Johnson, Mathew A.; Zumbrun, Kevin; Noble, Pascal

    2011-03-01

    Extending results of Oh and Zumbrun and of Johnson and Zumbrun for parabolic conservation laws, we show that spectral stability implies nonlinear stability for spatially periodic viscous roll wave solutions of the ...

  20. Saddle–node bifurcation of viscous profiles

    PubMed Central

    Achleitner, Franz; Szmolyan, Peter

    2012-01-01

    Traveling wave solutions of viscous conservation laws, that are associated to Lax shocks of the inviscid equation, have generically a transversal viscous profile. In the case of a non-transversal viscous profile we show by using Melnikov theory that a parametrized perturbation of the profile equation leads generically to a saddle–node bifurcation of these solutions. An example of this bifurcation in the context of magnetohydrodynamics is given. The spectral stability of the traveling waves generated in the saddle–node bifurcation is studied via an Evans function approach. It is shown that generically one real eigenvalue of the linearization of the viscous conservation law around the parametrized family of traveling waves changes its sign at the bifurcation point. Hence this bifurcation describes the basic mechanism of a stable traveling wave which becomes unstable in a saddle–node bifurcation. PMID:23576830

  1. Disintermediation in the Year 2010: Using Scenarios To Identify Key Issues and Relevance of IMPEL2 eLib Project.

    ERIC Educational Resources Information Center

    Edwards, Catherine; Day, Joan; Walton, Graham

    Among information workers, the term "disintermediation" has been used to describe the diminishing role of the intermediary associated with the electronic information environment. IMPEL2 is a JISC-funded e-Lib Project investigating the social, organizational, and cultural impacts of the growing electronic library in United Kingdom higher education.…

  2. Numerical simulation of unsteady viscous flows

    NASA Technical Reports Server (NTRS)

    Hankey, Wilbur L.

    1987-01-01

    Most unsteady viscous flows may be grouped into two categories, i.e., forced and self-sustained oscillations. Examples of forced oscillations occur in turbomachinery and in internal combustion engines while self-sustained oscillations prevail in vortex shedding, inlet buzz, and wing flutter. Numerical simulation of these phenomena was achieved due to the advancement of vector processor computers. Recent progress in the simulation of unsteady viscous flows is addressed.

  3. Multiplicity scaling in ideal and viscous hydrodynamics

    Microsoft Academic Search

    Huichao Song; Ulrich W. Heinz

    2008-01-01

    Using numerical results from ideal and viscous relativistic hydrodynamic simulations with three different equations of state, for Au+Au and Cu+Cu collisions at different centralities and initial energy densities, we explore the dependence of the eccentricity-scaled elliptic flow, v2\\/?, and the produced entropy fraction, DeltaS\\/S0, on the final charged hadron multiplicity density dNch\\/dy per unit transverse overlap area S,(1\\/S)dNch\\/dy. The viscous

  4. Pipe effect in viscous liquids

    E-print Network

    V. Capano; S. Esposito; G. Salesi

    2008-12-23

    A detailed experimental and theoretical study has been performed about a phenomenon, not previously reported in the literature, occurring in highly viscous liquids: the formation of a definite pipe structure induced by the passage of a heavy body, this structure lasting for quite a long time. A very rich phenomenology (including mechanical, optical and structural effects) associated with the formation of the pipe has been observed in different liquids. Actually, the peculiar dynamical evolution of that structure does not appear as a trivial manifestation of standard relaxation or spurious effects. In particular we have revealed different time scales during the evolution of the pipe and a non-monotonous decreasing of the persistence time with decreasing viscosity (with the appearance of at least two different maxima). A microscopic model consistent with the experimental data, where the pipe behaves as a cylindrical dielectric shell, has been proposed. The general time evolution of the structure has been described in terms of a simple thermodynamical model, predicting several peculiarities effectively observed.

  5. Well pump

    DOEpatents

    Ames, Kenneth R. (Pasco, WA); Doesburg, James M. (Chicago, IL)

    1987-01-01

    A well pump includes a piston and an inlet and/or outlet valve assembly of special structure. Each is formed of a body of organic polymer, preferably PTFE. Each includes a cavity in its upper portion and at least one passage leading from the cavity to the bottom of the block. A screen covers each cavity and a valve disk covers each screen. Flexible sealing flanges extend upwardly and downwardly from the periphery of the piston block. The outlet valve block has a sliding block and sealing fit with the piston rod.

  6. Examining Impelling and Disinhibiting Factors for Intimate Partner Violence in Veterans

    PubMed Central

    Taft, Casey T.; Suvak, Michael K.; Kachadourian, Lorig K.; Pinto, Lavinia A.; Miller, Mark M.; Knight, Jeffrey; Marx, Brian P.

    2013-01-01

    We examined correlates of intimate partner violence (IPV) in a military Veteran sample (N = 129) using Finkel’s (2007) framework for understanding the interactions between impelling and disinhibiting risk factors. Correlates investigated included head contact events (HCEs), posttraumatic stress disorder (PTSD) symptoms, and antisocial features. Results indicated that antisocial features were significantly associated with IPV at the bivariate level. PTSD symptoms also were associated with IPV, but this association was marginally significant. Tests of moderation provided support for the expectation that HCEs would potentiate associations between antisocial features and IPV. HCEs also moderated the association between PTSD symptoms and IPV. However, contrary to expectations, the opposite pattern emerged such that PTSD symptoms were associated with a higher rate of IPV for those without a history of HCEs. Study findings have potentially important implications for furthering our understanding of the complex etiology of IPV in this population. PMID:22369461

  7. Controls of Wellbore Flow Regimes on Pump Effluent Composition

    SciTech Connect

    James Martin-Hayden; plummer; Sanford Britt

    2014-01-01

    Where well water and formation water are compositionally different or heterogeneous, pump effluent composition will vary due to partial mixing and transport induced by pumping. Investigating influences of purging and sampling methodology on composition variability requires quantification of wellbore flow regimes and mixing. As a basis for this quantification, analytical models simulating Poiseuille flow were developed to calculate flow paths and travel times. Finite element modeling was used to incorporate influences of mixing. Parabolic velocity distributions within the screened interval accelerate with cumulative inflow approaching the pump intake while an annulus of inflowing formation water contracts uniformly to displace an axial cylinder of pre-pumping well water as pumping proceeds. Increased dispersive mixing forms a more diffuse formation water annulus and the contribution of formation water to pump effluent increases more rapidly. Models incorporating viscous flow and diffusion scale mixing show that initially pump effluent is predominantly pre-pumping well water and compositions vary most rapidly. After two screen volumes of pumping, 94% of pump effluent is inflowing formation water. Where the composition of formation water and pre-pumping well water are likely to be similar, pump effluent compositions will not vary significantly and may be collected during early purging or with passive sampling. However, where these compositions are expected to be considerably different or heterogeneous, compositions would be most variable during early pumping, that is, when samples are collected during low-flow sampling. Purging of two screen volumes would be required to stabilize the content and collect a sample consisting of 94% formation water.

  8. Submergible pumping apparatus

    Microsoft Academic Search

    R. J. Bookout; J. W. Jacobs; B. A. Pearson

    1985-01-01

    Submergible pumping apparatus for use in an oil or other well comprises, in a self-contained downhole unit, a double-acting reciprocating positive displacement pump for pumping well fluid, a reservoir containing power fluid for operating the double-acting pump, a rotary motor-driven positive displacement pump for supplying power fluid under pressure from the reservoir to operate the reciprocating pump, and a control

  9. Pumping unit

    SciTech Connect

    Pauls, D.A.

    1986-12-30

    A pumping unit is described for use at a well having a well head, comprising: support means; a pair of pitman arms, each of the pitman arms having a longitudinal axis and a first end portion and a second end portion; means including crank arm means for causing movement the pitman arms, the means for causing movement connected to the support means and to the first end portion of each of the pitman arms; a first strap having a width of at least inches and including a first end portion and a second end portion; a second strap having a width of at least three inches and including a first end portion and a second end portion, the second strap being separate from and spaced from the first strap; equalizer beam means being separate from each of the pitman arms and extending between the second end portion of each of the pitman arms. The pitman arms and the equalizer beam means cooperate with the first strap and the second strap to minimize the bending stress applied to the means for causing movement during operation of the pumping unit; connection means being separate from the equalizer beam means but engaging the equalizer beam means for use in interconnecting each of the first end portions of the first and second straps to the pitman arms and wherein each of the first and second straps contacts the equalizer beam means; and reciprocating means connected to the second end portions of the first and second straps and adapted to move relative to the well. The reciprocating means includes a polished rod and wherein all portions of the polished rod are positioned at an angle relative to the longitudinal axis of each of the pitman arms.

  10. Liquid metal pump

    DOEpatents

    Pennell, William E. (Greensburg, PA)

    1982-01-01

    The liquid metal pump comprises floating seal rings and attachment of the pump diffuser to the pump bowl for isolating structural deflections from the pump shaft bearings. The seal rings also eliminate precision machining on large assemblies by eliminating the need for a close tolerance fit between the mounting surfaces of the pump and the seals. The liquid metal pump also comprises a shaft support structure that is isolated from the pump housing for better preservation of alignment of shaft bearings. The shaft support structure also allows for complete removal of pump internals for inspection and repair.

  11. Simulating elliptic flow with viscous hydrodynamics

    SciTech Connect

    Dusling, K.; Teaney, D. [Department of Physics and Astronomy, State University of New York, Stony Brook, New York 11794-3800 (United States)

    2008-03-15

    In this work we simulate a viscous hydrodynamical model of noncentral Au-Au collisions in 2+1 dimensions, assuming longitudinal boost invariance. The model fluid equations were proposed by Oettinger and Grmela [Grmela, M., and Oettinger, H. C., Phys. Rev. E, 56, 6620 (1997)]. Freeze-out is signaled when the viscous corrections become large relative to the ideal terms. Then viscous corrections to the transverse momentum and differential elliptic flow spectra are calculated. When viscous corrections to the thermal distribution function are not included, the effects of viscosity on elliptic flow are modest. However, when these corrections are included, the elliptic flow is strongly modified at large p{sub T}. We also investigate the stability of the viscous results by comparing the nonideal components of the stress tensor ({pi}{sup ij}) and their influence on the v{sub 2} spectrum to the expectation of the Navier-Stokes equations ({pi}{sup ij}=-{eta}<{partial_derivative}{sub i}u{sub j}>). We argue that when the stress tensor deviates from the Navier-Stokes form the dissipative corrections to spectra are too large for a hydrodynamic description to be reliable. For typical Relativistic Heavy Ion Colloder initial conditions this happens for {eta}/s > or approx. 0.3.

  12. Mitigation of micro vibration by viscous dampers

    NASA Astrophysics Data System (ADS)

    Lin, Tzu-Kang; Chen, Chun-Chung; Chang, Kuo-Chun; Jay Lin, Chu-Chieh; Hwang, Jenn-Shin

    2009-12-01

    This study proposes a micro vibration mitigation system using viscous dampers to solve the problem of vibration in a high-tech building. Due to the operating frequency of the air conditioners and fundamental mode of the floors, a resonant phenomenon is occasionally experienced at the upper levels of the structure. Several strategies were considered, and viscous dampers combined with a suspension system were chosen to mitigate this annoying situation. A theoretical analysis was first executed to determine the optimal design value of the damper and the suspension spring. An efficient reduction in floor velocity of approximately 50 % was achieved by the proposed system. Practical verifications including a performance test of the micro-vibration-oriented dampers, the pragmatic application result, and a comparison in one-third octave spectrum was then carried out. The performance of the system was demonstrated by the data measured. It alleviated more trembling than was numerically expected. The energy absorbed by the viscous dampers is illustrated by the hysteresis loops and the one-third octave spectrum. It is found that with the proposed system, the vibration can be effectively captured by the viscous damper and converted to lower frequency-content tremors. The success of this project greatly supports the proposed standard two-stage analysis procedure for mitigating micro-vibration problems in practice. This research extends the use of viscous dampers to a new field.

  13. Frequency of seal disruption with the sarns centrifugal pump in postcardiotomy circulatory assist.

    PubMed

    Curtis, J J; Boley, T M; Walls, J T; Demmy, T L; Schmaltz, R A

    1994-03-01

    We have used the Sarns centrifugal pump for uni- or biventricular assist in 58 patients with postcardiotomy cardiogenic shock. This device utilizes a spinning impeller pump that is magnetically coupled to a motor imparting rotary motion to incoming perfusate. Nine patients (16%) experienced 22 device failures, which consisted of a nonvisible disruption of the seal within the pumphead. This allowed fluid to accumulate between the pumphead and the motor necessitating change of the pumphead. The time to seal disruption was 10-149 h (median 48). Of the 22 seal disruptions, 18 occurred in 73 left ventricular pumps (25%), and 4 occurred in 38 right ventricular pumps (11%) p = 0.015. Left ventricular pumps failed at 10-144 h (median 48), and right ventricular pumps failed at 48-149 h (median 83) p = 0.02. The Sarns centrifugal pump is dependable for its intended use of cardiopulmonary perfusion. However, when used for postcardiotomy assist, seal disruption should be expected. It occurs sooner and is more common during left ventricular assist. We recommend inspection of the magnet chamber for evidence of seal disruption every 12 h with left ventricular assist and every 24 h with right ventricular assist. PMID:8185492

  14. The PediPump: development status of a new pediatric ventricular assist device: update II.

    PubMed

    Duncan, Brian W; Dudzinski, David T; Gu, Lei; Mielke, Nicole; Noecker, Angela M; Kopcak, Michael W; Fukamachi, Kiyotaka; Cingoz, Faruk; Ootaki, Yoshio; Smith, William A

    2006-01-01

    The PediPump is a new ventricular assist device with a hydraulic output range designed for children from newborn infants to adolescents. The design is based on a mixed-flow rotary pump; the rotating assembly consists of a front impeller, front and rear radial magnetic bearings, and a central motor magnet. Two different implantable pumps were designed initially: an intravascular pump measuring 7 x 75 mm and an extravascular pump measuring 14 x 85 mm. Current prototypes are substantially smaller: The current intravascular version measures 4.5 x 55 mm, whereas the current extravascular version measures 11 x 70 mm. Both devices provide pressure and flows capable of supporting adults, far exceeding the initially defined physiologic requirements for children weighing 2 to 25 kg. This basic pump design may be used in acute or chronic clinical settings to provide right ventricular, left ventricular, or biventricular support. There are three objectives for the PediPump development program: 1) determination of basic engineering requirements for hardware and control logic including design analysis for system sizing, evaluation of control concepts, and bench testing of prototypes; 2) performance of preclinical anatomic fitting studies using CT-based 3D modeling; and 3) animal studies to provide characterization and reliability testing of the device. PMID:16966863

  15. Ion pump provides increased vacuum pumping speed

    NASA Technical Reports Server (NTRS)

    1965-01-01

    Multiple-cell ion pumps with increased vacuum pumping speed are used for producing ultrahigh vacuums in vacuum tubes and mass spectrometers. The pump has eight cathode-anode magnetron cells arranged in a cylinder which increase the surface area of the cathode.

  16. Mechanics of viscous vortex reconnection

    NASA Astrophysics Data System (ADS)

    Hussain, Fazle; Duraisamy, Karthik

    2011-02-01

    This work is motivated by our long-standing claim that reconnection of coherent structures is the dominant mechanism of jet noise generation and plays a key role in both energy cascade and fine-scale mixing in fluid turbulence [F. Hussain, Phys. Fluids 26, 2816 (1983); J. Fluid Mech. 173, 303 (1986)]. To shed further light on the mechanism involved and quantify its features, the reconnection of two antiparallel vortex tubes is studied by direct numerical simulation of the incompressible Navier-Stokes equations over a wide range (250-9000) of the vortex Reynolds number, Re (=circulation/viscosity) at much higher resolutions than have been attempted. Unlike magnetic or superfluid reconnections, viscous reconnection is never complete, leaving behind a part of the initial tubes as threads, which then undergo successive reconnections (our cascade and mixing scenarios) as the newly formed bridges recoil from each other by self-advection. We find that the time tR for orthogonal transfer of circulation scales as tR?Re-3/4. The shortest distance d between the tube centroids scales as d ?a[Re(t0-t)]3/4 before reconnection (collision) and as d ?b[Re(t -t0)]2 after reconnection (repulsion), where t0 is the instant of smallest separation between vortex centroids. We find that b is a constant, thus suggesting self-similarity, but a is dependent on Re. Bridge repulsion is faster than collision and is more autonomous as local induction predominates, and, given the associated acceleration of vorticity, is potentially a source of intense sound generation. At the higher Re studied, the tails of the colliding threads are compressed into a planar jet with multiple vortex pairs. For Re>6000, there is an avalanche of smaller scales during the reconnection, the rate of small scale generation and the spectral content (in vorticity, transfer function and dissipation spectra) being quite consistent with the structures visualized by the ?2 criterion. The maximum rate of vortex circulation transfer, enstrophy production, and dissipation scale as Re1, Re7/4, and Re-1/2, respectively. A more detailed study of subsequent reconnection of threads requires much higher-resolution simulations that are currently not feasible.

  17. Design and testing of a tandem row pump inducer

    NASA Technical Reports Server (NTRS)

    Etter, R. J.

    1974-01-01

    The design and testing of a tandem row pump inducer having a supercavitating first stage with a 0.60 hub ratio is presented. The second stage tested was a helical impeller with a 0.70 hub ratio. A cubic arc transition was utilized to accomplish the hub change. The first stage had two blades and the free-vortex design approach was empirically modified based on previous experience. The recommended second stage design having four blades and using cambered blade section is presented but the model was not built or tested. The more simple helix was built instead to reduce cost. Data taken included head generation, cavitation observations and unsteady head fluctuations over the 0-100Hz range.

  18. Determination of the influence of a clearance between the case and blade ends of the semi-open impeller on the centrifugal compressor stage characteristics

    Microsoft Academic Search

    V. A. Futin

    2011-01-01

    The influence of the clearance between the case and blade ends of the semi-open impeller on the centrifugal stage characteristics\\u000a is considered using the experimental data and numerical calculation results.

  19. Simulation of 3-D viscous compressible flow in multistage turbomachinery by finite element methods

    NASA Astrophysics Data System (ADS)

    Sleiman, Mohamad

    1999-11-01

    The flow in a multistage turbomachinery blade row is compressible, viscous, and unsteady. Complex flow features such as boundary layers, wake migration from upstream blade rows, shocks, tip leakage jets, and vortices interact together as the flow convects through the stages. These interactions contribute significantly to the aerodynamic losses of the system and degrade the performance of the machine. The unsteadiness also leads to blade vibration and a shortening of its life. It is therefore difficult to optimize the design of a blade row, whether aerodynamically or structurally, in isolation, without accounting for the effects of the upstream and downstream rows. The effects of axial spacing, blade count, clocking (relative position of follow-up rotors with respect to wakes shed by upstream ones), and levels of unsteadiness may have a significance on performance and durability. In this Thesis, finite element formulations for the simulation of multistage turbomachinery are presented in terms of the Reynolds-averaged Navier-Stokes equations for three-dimensional steady or unsteady, viscous, compressible, turbulent flows. Three methodologies are presented and compared. First, a steady multistage analysis using a a-mixing- plane model has been implemented and has been validated against engine data. For axial machines, it has been found that the mixing plane simulation methods match very well the experimental data. However, the results for a centrifugal stage, consisting of an impeller followed by a vane diffuser of equal pitch, show flagrant inconsistency with engine performance data, indicating that the mixing plane method has been found to be inappropriate for centrifugal machines. Following these findings, a more complete unsteady multistage model has been devised for a configuration with equal number of rotor and stator blades (equal pitches). Non-matching grids are used at the rotor-stator interface and an implicit interpolation procedure devised to ensure continuity of fluxes across. This permits the rotor and stator equations to be solved in a fully- coupled manner, allowing larger time steps in attaining a time-periodic solution. This equal pitch approach has been validated on the complex geometry of a centrifugal stage. Finally, for a stage configuration with unequal pitches, the time-inclined method, developed by Giles (1991) for 2-D viscous compressible flow, has been extended to 3-D and formulated in terms of the physical solution vector U, rather than Q, a non-physical one. The method has been evaluated for unsteady flow through a rotor blade passage of the power turbine of a turboprop.

  20. Effect of impeller type and mechanical agitation on the mass transfer and power consumption aspects of ASBR operation treating synthetic wastewater.

    PubMed

    Michelan, Rogério; Zimmer, Thiago R; Rodrigues, José A D; Ratusznei, Suzana M; de Moraes, Deovaldo; Zaiat, Marcelo; Foresti, Eugenio

    2009-03-01

    The effect of flow type and rotor speed was investigated in a round-bottom reactor with 5 L useful volume containing 2.0 L of granular biomass. The reactor treated 2.0 L of synthetic wastewater with a concentration of 800 mgCOD/L in 8-h cycles at 30 degrees C. Five impellers, commonly used in biological processes, have been employed to this end, namely: a turbine and a paddle impeller with six-vertical-flat-blades, a turbine and a paddle impeller with six-45 degrees -inclined-flat-blades and a three-blade-helix impeller. Results showed that altering impeller type and rotor speed did not significantly affect system stability and performance. Average organic matter removal efficiency was about 84% for filtered samples, total volatile acids concentration was below 20 mgHAc/L and bicarbonate alkalinity a little less than 400 mgCaCO3/L for most of the investigated conditions. However, analysis of the first-order kinetic model constants showed that alteration in rotor speed resulted in an increase in the values of the kinetic constants (for instance, from 0.57 h(-1) at 50 rpm to 0.84 h(-1) at 75 rpm when the paddle impeller with six-45 degrees -inclined-flat-blades was used) and that axial flow in mechanically stirred reactors is preferable over radial-flow when the vertical-flat-blade impeller is compared to the inclined-flat-blade impeller (for instance at 75 rpm, from 0.52 h(-1) with the six-flat-blade-paddle impeller to 0.84 h(-1) with the six-45 degrees -inclined-flat-blade-paddle impeller), demonstrating that there is a rotor speed and an impeller type that maximize solid-liquid mass transfer in the reaction medium. Furthermore, power consumption studies in this reduced reactor volume showed that no high power transfer is required to improve mass transfer (less than 0.6 kW/10(3)m3). PMID:18814952

  1. Hyperresistivity due to viscous tearing mode turbulence

    SciTech Connect

    Finn, John M. [T-15, Plasma Theory, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)

    2005-09-15

    The quasilinear hyperresistivity coefficient D{sub H} for flattening a current profile in resistive magnetohydrodynamics is computed. It is found that D{sub H} is independent of {delta}{sup '}, the constant-{psi} matching parameter, for viscous tearing modes. This is in contrast to the situation for inertial tearing modes, for which D{sub H} scales as {delta}{sup '-1/5}. It is reasonable to consider viscous rather than inertial tearing modes for computing D{sub H} because inertial tearing modes cross over to the viscous regime near quasilinear saturation, when their growth rates are sufficiently small. This quasilinear calculation of hyperresistivity related to a spectrum of tearing modes invokes the assumption that the tearing layers overlap. This is in contrast to the usual assumption of overlap of magnetic islands, i.e., magnetic field line chaos.

  2. Using CFD to predict the behavior of power law fluids near axial-flow impellers operating in the transitional flow regime

    Microsoft Academic Search

    W. Kelly; B. Gigas

    2003-01-01

    A computational fluid dynamics (CFD) model of flow in a mixing tank with a single axial-flow impeller was developed with the FluentTM software. The model consists of an unstructured hexagonal mesh (158,000 total cells), dense in the region 5mm from the surface of the impeller. The flow was modeled as laminar and a multiple reference frame approach was used to

  3. A comprehensive comparison of mixing, mass transfer, Chinese hamster ovary cell growth, and antibody production using Rushton turbine and marine impellers.

    PubMed

    Sandadi, Sandeepa; Pedersen, Henrik; Bowers, John S; Rendeiro, Dennis

    2011-09-01

    Large scale production of monoclonal antibodies has been accomplished using bioreactors with different length to diameter ratios, and diverse impeller and sparger designs. The differences in these physical attributes often result in dissimilar mass transfer, mechanical stresses due to turbulence and mixing inside the bioreactor that may lead to disparities in cell growth and antibody production. A rational analysis of impeller design parameters on cell growth, protein expression levels and subsequent antibody production is needed to understand such differences. The purpose of this study was to examine the impact of Rushton turbine and marine impeller designs on Chinese hamster ovary (CHO) cell growth and metabolism, and antibody production and quality. Experiments to evaluate mass transfer and mixing characteristics were conducted to determine if the nutrient requirements of the culture would be met. The analysis of mixing times indicated significant differences between marine and Rushton turbine impellers at the same power input per unit volume of liquid (P/V). However, no significant differences were observed between the two impellers at constant P/V with respect to oxygen and carbon dioxide mass transfer properties. Experiments were conducted with CHO cells to determine the impact of different flow patterns arising from the use of different impellers on cell growth, metabolism and antibody production. The analysis of cell culture data did not indicate any significant differences in any of the measured or calculated variables between marine and Rushton turbine impellers. More importantly, this study was able to demonstrate that the quality of the antibody was not altered with a change in the impeller geometry. PMID:21505815

  4. Gyro pump wear and deformation analysis in vivo study: creep deformation.

    PubMed

    Nakata, K; Yoshikawa, M; Takano, T; Maeda, T; Nonaka, K; Linneweber, J; Kawahito, S; Glueck, J; Fujisawa, A; Makinouchi, K; Yokokawa, M; Nosé, Y

    2000-08-01

    The Gyro pump has a double pivot bearing system to support its impeller. In this study, the integrity of the bearing system was examined after ex vivo studies. The pumps were implanted into calves and evaluated for different periods as a paracorporeal left ventricular assist device (LVAD). One pump was subjected to a test of 30 days, 1 for 15 days, 4 for 14 days, 1 for 10 days, 1 for 7 days, 2 for 4 days, and 4 for 2 days. One additional pump was subjected to percutaneous cardiopulmonary support (PCPS) condition for 6 days (total pressure head 500 mm Hg with a pump flow rate of 3 L/min). The anticoagulation treatment consisted of a continuous administration of heparin to maintain an achieved clotting time (ACT) of 200-250 s during the LVAD study and 250-300 s during the PCPS study. After the experiment, the pumps were disassembled, and the wear and deformation of male and female bearings were analyzed. There were no dimensional changes on male bearings but there were on female bearings. Wear and deformation of the female bearings were calculated as follows: wear and deformation = (depth of female before pumping) - (depth after pumping). Thirteen assembled Gyro pumps were disassembled to measure the depth of the female bearings before pumping. There was no statistical relationship between the wear and deformation and the motor speed x driving period. From these results, the deformation was not due to wear but to the creep or elastic deformation. This study suggested that the double pivot bearing system of the Gyro pump is highly durable. PMID:10971256

  5. Dynamic wetting of viscous and viscoelastic fluids

    NASA Astrophysics Data System (ADS)

    Wei, Yuli

    Dynamic wetting poses a complex fluid mechanical problem of both fundamental and technological importance. This complexity arises because the fundamental geometry of the wedge-like region near the moving contact line requires that fluid elements experience ever increasing deformation rates as they pass into and out of that region. Thus, somewhere in the flow field, relaxation modes caused by segmental and chain motions in a viscous polymeric fluid may be unable to relax, leading to nonlinear stresses and possible changes in the shape of the deformable free surface. In this thesis, we investigate the wetting behavior of model viscoelastic fluids, Boger fluids, and the viscous oligomeric fluids which are the base solvents in these Boger fluids. We determine that the dominant relaxation mode in Boger fluids has only small effects on both viscous bending and dynamic contact angles even approaching the air entrainment limit. A lubrication analysis, used to examine the impact of the linear elasticity due to dominant relaxation mode, also shows only small effects on the interface curvature and on the dynamic contact angle. The viscous oligomeric base fluids, which have only very short relaxation times, also show deviations from the viscous bending that a Newtonian fluid exhibits near the contact line. Our experiments prove that these deviations do not arise due to the interactions between the fluid and the solid surface. It is very possible that this behavior arises from the influence of the non-Newtonian behavior at a small length scale on the Newtonian hydrodynamics at larger distances from the contact line. Finally, a new relaxation regime has been discovered as the final static contact angle is approached in the spontaneous relaxation of the viscous fluids with non-zero static contact angles. This new regime may be due to slow rearrangements of the polymeric molecules altering the static force balance at the contact line.

  6. Viscous hydrodynamics for strongly anisotropic expansion

    NASA Astrophysics Data System (ADS)

    Heinz, Ulrich; Bazow, Dennis; Strickland, Michael

    2014-11-01

    A new formulation of second-order viscous hydrodynamics, based on an expansion around a locally anisotropic momentum distribution, is presented. It generalizes the previously developed formalism of anisotropic hydrodynamics (AHYDRO) to include a complete set of dissipative currents for which equations of motion are derived by solving the Boltzmann equation in the 14-moment approximation. By solving the VAHYDRO equations for a transversally homogeneous, longitudinally boost-invariant system ((0 + 1)-dimensional expansion) and comparing with the exact solution of the Boltzmann equation in relaxation-time approximation we show that VAHYDRO performs much better than all other known second-order viscous hydrodynamic approximations.

  7. Numerical simulation of viscous transonic airfoil flows

    NASA Technical Reports Server (NTRS)

    Coakley, Thomas J.

    1987-01-01

    Numerical simulations of transonic airfoil flows using the Reynolds-averaged Navier-Stokes equations and various turbulence models are presented and compared with experimental data. Three different airfoils were investigated under varying flow conditions ranging from subcritical unseparated flows to supercritical separated flows. The turbulence models investigated consisted of three zero-equation models and one two-equation model. For unseparated flows involving weak viscous-inviscid interactions, the four models were comparable in their agreement with experiment. For separated flows involving strong viscous-inviscid interactions, the nonequilibrium zero-equation model of Johnson and King gave the best overall agreement with experiment.

  8. Whole blood pumping with a microthrottle pump

    PubMed Central

    Davies, M. J.; Johnston, I. D.; Tan, C. K. L.; Tracey, M. C.

    2010-01-01

    We have previously reported that microthrottle pumps (MTPs) display the capacity to pump solid phase suspensions such as polystyrene beads which prove challenging to most microfluidic pumps. In this paper we report employing a linear microthrottle pump (LMTP) to pump whole, undiluted, anticoagulated, human venous blood at 200 ?l min?1 with minimal erythrocyte lysis and no observed pump blockage. LMTPs are particularly well suited to particle suspension transport by virtue of their relatively unimpeded internal flow-path. Micropumping of whole blood represents a rigorous real-world test of cell suspension transport given blood’s high cell content by volume and erythrocytes’ relative fragility. A modification of the standard Drabkin method and its validation to spectrophotometrically quantify low levels of erythrocyte lysis by hemoglobin release is also reported. Erythrocyte lysis rates resulting from transport via LMTP are determined to be below one cell in 500 at a pumping rate of 102 ?l min?1. PMID:21264059

  9. Hydraulic pump

    SciTech Connect

    Polak, P.R.; Jantzen, D.E.

    1984-05-15

    This invention relates to an improved pump jack characterized by a hollow piston rod which telescopes down over the sucker rod to which it is clamped for reciprocating motion. The cylinder, in turn, is fastened in fixed position directly to the upper exposed end of the well casing. As fluid is introduced into the lower end of the cylinder it raises the piston into engagement with a pushrod housed in the upper cylinder head that lifts switch-actuating means associated therewith into a position operative to actuate a switch located adjacent thereto thereby causing the latter to change state and actuate a multi-function solenoid valve so as to cut off fluid flow to the cylinder. As gravity lowers the sucker rod and piston exhausting the hydraulic fluid therebeneath, an adjustable stop engages the pushrod from above so as to return it together with the switch-actuating means associated therewith to their original positions thereby resetting the switch to complete the operating cycle.

  10. Centrifugal pump fuel system

    Microsoft Academic Search

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

    1993-01-01

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

  11. Submergible pump installation

    Microsoft Academic Search

    D. F. Taylor; W. G. Boyle

    1984-01-01

    A submergible pump installation for wells comprises a submergible pump assembly adapted to be landed in position within the well bore for pumping well fluids to the surface, together with a safety system for the well including a subsurface valve or valves for maintaining the well under control as the pump is run into and removed from the well. At

  12. Multiple pump housing

    SciTech Connect

    Donoho, II, Michael R. (Edelstein, IL); Elliott, Christopher M. (Metamora, IL)

    2010-03-23

    A fluid delivery system includes a first pump having a first drive assembly, a second pump having a second drive assembly, and a pump housing. At least a portion of each of the first and second pumps are located in the housing.

  13. Sensorless pump operation estimation

    Microsoft Academic Search

    Tero Ahonen; Jussi Tamminen; Jero Ahola; Juha Kestilä

    2009-01-01

    Pumps are widely used in industrial applications, and they account for nearly a quarter of the electric energy consumption in the European industry. Pumps are often overdimensioned or they may be driven inefficiently, which causes unnecessary energy costs. If the pump drive is not equipped with appropriate measurements, inefficient pump operation may remain undetected for years and lead to a

  14. Modelling of Mass Transfer in Gas-Liquid Stirred Tanks Agitated by Rushton Turbine and CD6 Impeller

    Microsoft Academic Search

    J. Gimbun; C. D. Rielly; Z. K. Nagy

    A combined computational fluid dynamics (CFD) and population balance model (PBM) approach has been applied to simulate gas-liquid stirred tanks agitated by (i) a Rushton turbine and (ii) a CD-6 impeller, operating at aeration numbers from 0.017 to 0.038. The multiphase simulations were realised via an Eulerian-Eulerian two-fluid model and the drag coefficient of spherical and distorted bubbles was modelled

  15. Open-Source Syringe Pump Library

    PubMed Central

    Wijnen, Bas; Hunt, Emily J.; Anzalone, Gerald C.; Pearce, Joshua M.

    2014-01-01

    This article explores a new open-source method for developing and manufacturing high-quality scientific equipment suitable for use in virtually any laboratory. A syringe pump was designed using freely available open-source computer aided design (CAD) software and manufactured using an open-source RepRap 3-D printer and readily available parts. The design, bill of materials and assembly instructions are globally available to anyone wishing to use them. Details are provided covering the use of the CAD software and the RepRap 3-D printer. The use of an open-source Rasberry Pi computer as a wireless control device is also illustrated. Performance of the syringe pump was assessed and the methods used for assessment are detailed. The cost of the entire system, including the controller and web-based control interface, is on the order of 5% or less than one would expect to pay for a commercial syringe pump having similar performance. The design should suit the needs of a given research activity requiring a syringe pump including carefully controlled dosing of reagents, pharmaceuticals, and delivery of viscous 3-D printer media among other applications. PMID:25229451

  16. Investigation of Flow in a Centrifugal Pump

    NASA Technical Reports Server (NTRS)

    Fischer, Karl

    1946-01-01

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

  17. Experimental and computational results from the NASA Lewis low-speed centrifugal impeller at design and part-flow conditions

    SciTech Connect

    Chriss, R.M.; Wood, J.R. [National Aeronautics and Space Administration, Cleveland, OH (United States). Lewis Research Center; Hathaway, M.D. [Army Research Lab., Cleveland, OH (United States). Vehicle Propulsion Directorate

    1996-01-01

    The NASA Lewis Low-Speed Centrifugal Compressor (LSCC) has been investigated with laser anemometry and computational analysis at two flow conditions: the design condition as well as a lower mass flow condition. Previously reported experimental and computational results at the design condition are in the literature (Hathaway et al., 1993). In that paper extensive analysis showed that inducer blade boundary layers are centrifuged outward and entrained into the tip clearance flow and hence contribute significantly to the throughflow wake. In this report results are presented for a lower mass flow condition along with further results from the design case. The data set contained herein consists of three-dimensional laser velocimeter results upstream, inside, and downstream of the impeller. In many locations data have been obtained in the blade and endwall boundary layers. The data are presented in the form of throughflow velocity contours as well as secondary flow vectors. The results reported herein illustrate the effects of flow rate on the development of the throughflow momentum wake as well as on the secondary flow. The computational results presented confirm the ability of modern computational tools to model the complex flow in a subsonic centrifugal compressor accurately. However, the blade tip shape and tip clearance must be known in order to properly simulate the flow physics. In addition, the ability to predict changes in the throughflow wake, which is largely fed by the tip clearance flow, as the impeller is throttled should give designers much better confidence in using computational tools to improve impeller performance.

  18. Velocity profiles and shear strain rate variability in the USP Dissolution Testing Apparatus 2 at different impeller agitation speeds.

    PubMed

    Bai, Ge; Wang, Yimin; Armenante, Piero M

    2011-01-17

    The fluid velocity profiles at different locations inside a standard USP Dissolution Testing Apparatus 2 were experimentally obtained via Laser Doppler Velocimetry (LDV) at three impeller agitations speeds, namely 50rpm, 75rpm and 100rpm. The experimental results were compared with the predictions obtained with Computational Fluid Dynamics (CFD) where the ?-? model with low Reynolds number correction was used to account for turbulence effects. In general, good agreement was found between the experimental LDV velocity measurements and the CFD simulation predictions. The non-dimensional tangential, axial and radial velocity profiles (scaled with the impeller tip speed) and the flow pattern were found to be nearly independent of the agitation speed in most regions of the vessel, implying that increasing the agitation speed generally produced a corresponding increase in the local values of the velocity. However, the velocity profiles and flow pattern in the inner core region just below the impeller, where the dissolving tablet is usually located, were found to be much less sensitive to agitation speed. In this region, the axial and radial velocities were especially low and were not significantly affected by agitation increases. This inner core region at the center of the vessel bottom persisted irrespective of agitation intensity. The CFD predictions also indicated that increasing the agitation speed resulted in a higher shear strain rate distribution along the vessel bottom, although the strain rate was always very low at the center of the vessel bottom, even when the agitation speed was increased. PMID:20883758

  19. Viscous Populations and Their Support for Reciprocal Cooperation

    E-print Network

    Rowe, Jon

    Population Cooperative Model To study, among other things, reciprocal cooperation in viscous populations, weViscous Populations and Their Support for Reciprocal Cooperation James A. R. Marshall* Complex Abstract Viscous populations, those whose members are spatially distributed and have limited mobility

  20. The Ghost Fluid Method for Viscous Flows Ronald P. Fedkiw

    E-print Network

    Soatto, Stefano

    Equations 2.1 Navier-Stokes Equations The basic equations for viscous compressible ow are the Navier-Stokes the extended formulation to the viscous Navier-Stokes equations. The resulting numerical method is robust for material interfaces in the viscous Navier-Stokes equations. The GFM will implicitly enforce the jump

  1. Viscous Dark Energy and Generalized Second Law of Thermodynamics

    Microsoft Academic Search

    M. R. Setare; A. Sheykhi

    2010-01-01

    We examine the validity of the generalized second law of thermodynamics in a non-flat universe in the presence of viscous dark energy. First we assume that the universe is filled only with viscous dark energy. Then, we extend our study to the case where there is an interaction between viscous dark energy and pressureless dark matter. We examine the time

  2. Viscous Driven-Cavity Solver: User's Manual

    NASA Technical Reports Server (NTRS)

    Wood, William A.

    1997-01-01

    The viscous driven-cavity problem is solved using a stream-function and vorticity formulation for the incompressible Navier-Stokes equations. This report provides the user's manual and FORTRAN code for the set of governing equations presented in NASA TM-110262.

  3. Can altruism evolve in purely viscous populations?

    Microsoft Academic Search

    D. S. Wilson; G. B. Pollock; L. A. Dugatkin

    1992-01-01

    Summary  Limited dispersal is often thought to facilitate the evolution of altruism by increasing the degree of relatedness among interacting individuals. Limited dispersal can have additional effects, however, such as local population regulation, that inhibits the evolution of altruism. Many models of structured populations assume that a viscous stage of the life cycle alternates with a global mixing stage, which allows

  4. Viscous hypersonic flows for various aerophysical models

    Microsoft Academic Search

    I. V. Egorov; V. S. Nikol'skii

    1996-01-01

    The results of mathematical simulation of hypersonic air flow past a sphere with allowance for chemical nonequilibrium and ionization are presented. The calculated data are obtained on the basis of a numerical solution of the Navier-Stokes equations and the hypersonic viscous shock layer equations. The equilibrium radiation temperature of the body surface, the pressure, and the shock wave detachment are

  5. Experimental study of the influence of flow passage subtle variation on mixed-flow pump performance

    NASA Astrophysics Data System (ADS)

    Bing, Hao; Cao, Shuliang

    2014-05-01

    In the mixed-flow pump design, the shape of the flow passage can directly affect the flow capacity and the internal flow, thus influencing hydraulic performance, cavitation performance and operation stability of the mixed-flow pump. However, there is currently a lack of experimental research on the influence mechanism. Therefore, in order to analyze the effects of subtle variations of the flow passage on the mixed-flow pump performance, the frustum cone surface of the end part of inlet contraction flow passage of the mixed-flow pump is processed into a cylindrical surface and a test rig is built to carry out the hydraulic performance experiment. In this experiment, parameters, such as the head, the efficiency, and the shaft power, are measured, and the pressure fluctuation and the noise signal are also collected. The research results suggest that after processing the inlet flow passage, the head of the mixed-flow pump significantly goes down; the best efficiency of the mixed-flow pump drops by approximately 1.5%, the efficiency decreases more significantly under the large flow rate; the shaft power slightly increases under the large flow rate, slightly decreases under the small flow rate. In addition, the pressure fluctuation amplitudes on both the impeller inlet and the diffuser outlet increase significantly with more drastic pressure fluctuations and significantly lower stability of the internal flow of the mixed-flow pump. At the same time, the noise dramatically increases. Overall speaking, the subtle variation of the inlet flow passage leads to a significant change of the mixed-flow pump performance, thus suggesting a special attention to the optimization of flow passage. This paper investigates the influence of the flow passage variation on the mixed-flow pump performance by experiment, which will benefit the optimal design of the flow passage of the mixed-flow pump.

  6. The Three Regimes of Miscible Viscous Fingering

    NASA Astrophysics Data System (ADS)

    Chui, J.; Szulczewski, M.; Jha, B.; Juanes, R.

    2012-12-01

    Viscous fingering, the hydrodynamic instability that sets in when a lower viscosity fluid displaces a higher viscosity fluid, creates complex patterns in porous media flows. Fundamental facets of the displacement process, such as volumetric sweep and mixing efficiency, depend strongly on the type of pattern created by the uneven front of the less viscous fluid. The interface created from these fingering patterns affects mixing, and therefore is of critical importance in applications such as enhanced oil recovery and groundwater remediation. This work focuses on the evolution of a fingering interface over time, and how this evolution changes depending on the injection rate and viscosity ratio of the two miscible fluids. Initial results from both experiments and simulations show that the interface growth rate exhibits three different regimes (see figure): 1) Compact radial expansion before fingering 2) Accelerated growth of interface length due to fingering 3) Radial expansion with fixed fingers Furthermore, the experiments and simulations suggest that these are power law regimes, with viscous fingering affecting the intermediate and last regimes. The fingers affect the interface growth at intermediate times, but affect only the coefficient of scaling at late times. Since the fingers affect interface growth differently over time, understanding the mechanisms behind when and how the fingering pattern moves through these three regimes is necessary for accurately determining the interface available for mixing when viscous fingering is observed.he interface length of a fingering pattern moves through three regimes, which are characterized by the changes in the power law between total interface length and time. This fingering pattern is created from an injection of fluid ten times less viscous than the defending fluid at a rate of 0.002 mL per minute.

  7. An Experimental Study of Cavitation Detection in a Centrifugal Pump Using Envelope Analysis

    NASA Astrophysics Data System (ADS)

    Tan, Chek Zin; Leong, M. Salman

    Cavitation represents one of the most common faults in pumps and could potentially lead to a series of failure in mechanical seal, impeller, bearing, shaft, motor, etc. In this work, an experimental rig was setup to investigate cavitation detection using vibration envelope analysis method, and measured parameters included sound, pressure and flow rate for feasibility of cavitation detection. The experiment testing included 3 operating points of the centrifugal pump (B.E.P, 90% of B.E.P and 80% of B.E.P). Suction pressure of the centrifugal pump was decreased gradually until the inception point of cavitation. Vibration measurements were undertaken at various locations including casing, bearing, suction and discharge flange of the centrifugal pump. Comparisons of envelope spectrums under cavitating and non-cavitating conditions were presented. Envelope analysis was proven useful in detecting cavitation over the 3 testing conditions. During the normal operating condition, vibration peak synchronous to rotational speed was more pronounced. It was however during cavitation condition, the half order sub-harmonic vibration component was clearly evident in the envelope spectrums undertaken at all measurement locations except at the pump bearing. The possible explanation of the strong sub-harmonic (½ of BPF) during cavitation existence in the centrifugal pump was due to insufficient time for the bubbles to collapse completely before the end of the single cycle.

  8. Sensorless Viscosity Measurement in a Magnetically-Levitated Rotary Blood Pump.

    PubMed

    Hijikata, Wataru; Rao, Jun; Abe, Shodai; Takatani, Setsuo; Shinshi, Tadahiko

    2015-07-01

    Controlling the flow rate in an implantable rotary blood pump based on the physiological demand made by the body is important. Even though various methods to estimate the flow rate without using a flow meter have been proposed, no adequate method for measuring the blood viscosity, which is necessary for an accurate estimate of the flow rate, without using additional sensors or mechanisms in a noninvasive way, has yet been realized. We have developed a sensorless method for measuring viscosity in magnetically levitated rotary blood pumps, which requires no additional sensors or mechanisms. By applying vibrational excitation to the impeller using a magnetic bearing, we measured the viscosity of the working fluid by measuring the phase difference between the current in the magnetic bearing and the displacement of the impeller. The measured viscosity showed a high correlation (R(2) ?>?0.992) with respect to a reference viscosity. The mean absolute deviation of the measured viscosity was 0.12?mPa·s for several working fluids with viscosities ranging from 1.18 to 5.12?mPa·s. The proposed sensorless measurement method has the possibility of being utilized for estimating flow rate. PMID:25920684

  9. Flow measurements in a model centrifugal pump by 3-D PIV

    NASA Astrophysics Data System (ADS)

    Yang, H.; Xu, H. R.; Liu, C.

    2012-11-01

    PIV (Particle Image Velocimetry), as an non-intrusive flow measurements technology, is widely used to investigate the flow fields in many areas. 3-D (three Dimensional) PIV has seldom been used to measure flow field in rotational impeller of centrifugal pump due to the difficulty of calibration in samll space. In this article, a specially manufactured water tank was used to perform the calibration for 3-D PIV measurement. The instantaneous absolute velocity in one impeller passage was obtained by merging of three sub zones and the relative velocity was acquired by velocity decomposition. The result shows that, when the pump runs at the condition of design flow rate, the radial component velocity Wr appears a concave distribution except the condition of R=45 mm. With the increase of radius, the circumference location of the minimum radial component velocity Wr moves from the pressure side to the suction side. At the same time, the tangential component velocity W? on the suction side decreases gradually with the increase of radius, while the component on the pressure side increases gradually. The secondary flow in different radius section has also been shown. At last, the error of PIV measurements was analyzed, which shows that the test results are accurate and the measured data is reliable.

  10. Numerical simulation of cavitation effects influenced by centrifugal pump inlet parameters

    NASA Astrophysics Data System (ADS)

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

    2015-01-01

    Cavitation has great influence on performance of the centrifugal pump. However, there is still no effective design to overcome this problem. Blade leading edge of centrifugal pump impeller is the initial position of cavitation. The leading edge geometry shape not only has a great influence on the cavitation inception and its development, but also a great influence on the flow state near the impeller inlet. In this paper, the numerical simulation method is adopted. Cavitation of four different models (including rectangular-shape blade model, circular-arc-shape blade model, elliptical-shape blade model and cusp-shape blade model) are simulated under the same condition by changing the NPSHA value. The influence of different blade models on cavitation performance is analyzed. The results show that the deviation between the simulated data and experimental data is within the deviation range. The head of rectangular-shape blade model and circular-arc-shape blade model are higher than those of elliptical-shape blade model and cusp-shape blade model. However, the head of rectangular-shape blade model and circular-arc-shape blade model is smaller than the latter under the low effective cavitation margin. What's more, the head of the models with trimmed blade are higher than the head of the models with untrimmed blade under the working condition but are smaller under the low effective cavitation margin.

  11. Evaluation of static mixer flow enhancements for cryogenic viscous compressor prototype for ITER vacuum system

    NASA Astrophysics Data System (ADS)

    Duckworth, Robert C.; Baylor, Larry R.; Meitner, Steven J.; Combs, Stephen K.; Ha, Tam; Morrow, Michael; Biewer, T.; Rasmussen, David A.; Hechler, Michael P.; Pearce, Robert J. H.; Dremel, Mattias; Boissin, J.-C.

    2014-01-01

    As part of the U.S. ITER contribution to the vacuum systems for the ITER fusion project, a cryogenic viscous compressor (CVC) is being designed and fabricated to cryopump hydrogenic gases in the torus and neutral beam exhaust streams and to regenerate the collected gases to controlled pressures such that they can be mechanically pumped with controlled flows to the tritium reprocessing facility. One critical element of the CVC design that required additional investigation was the determination of flow rates of the low pressure (up to 1000 Pa) exhaust stream that would allow for complete pumping of hydrogenic gases while permitting trace levels of helium to pass through the CVC to be pumped by conventional vacuum pumps. A sub-scale prototype test facility was utilized to determine the effectiveness of a static mixer pump tube concept, which consisted of a series of rotated twisted elements brazed into a 2-mm thick, 5-cm diameter stainless steel tube. Cold helium gas flow provided by a dewar and helium transfer line was used to cool the exterior of the static mixer pump tube. Deuterium gas was mixed with helium gas through flow controllers at different concentrations while the composition of the exhaust gas was monitored with a Penning gauge and optical spectrometer to determine the effectiveness of the static mixer. It was found that with tube wall temperatures between 6 K and 9 K, the deuterium gas was completely cryopumped and only helium passed through the tube. These results have been used to design the cooling geometry and the static mixer pump tubes in the full-scale CVC prototype.

  12. Evaluation of Static Mixer Flow Enhancements for Cryogenic Viscous Compressor Prototype for ITER Vacuum System

    SciTech Connect

    Duckworth, Robert C [ORNL] [ORNL; Baylor, Larry R [ORNL] [ORNL; Meitner, Steven J [ORNL] [ORNL; Combs, Stephen Kirk [ORNL] [ORNL; Ha, Tam T [ORNL] [ORNL; Morrow, Michael [ORNL] [ORNL; Biewer, Theodore M [ORNL] [ORNL; Rasmussen, David A [ORNL] [ORNL; Hechler, Michael P [ORNL] [ORNL; Pearce, R.J.H. [ITER Organization, Cadarache, France] [ITER Organization, Cadarache, France; Dremel, M. [ITER Organization, Cadarache, France] [ITER Organization, Cadarache, France; Boissin, Jean Claude [Consultant] [Consultant

    2014-01-01

    As part of the U.S. ITER contribution to the vacuum systems for the ITER fusion project, a cryogenic viscous compressor (CVC) is being designed and fabricated to cryopump hydrogenic gases in the torus and neutral beam exhaust streams and to regenerate the collected gases to controlled pressures such that they can be mechanically pumped with controlled flows to the tritium reprocessing facility. One critical element of the CVC design that required additional investigation was the determination of flow rates of the low pressure (50 to 1000 Pa) exhaust stream that would allow for complete pumping of hydrogenic gases while permitting trace levels of helium to pass through the CVC to be pumped by conventional vacuum pumps. A sub-scale prototype test facility was utilized to determine the effectiveness of a static mixer pump tube concept, which consisted of a series of rotated twisted elements brazed into a 2-mm thick, 5-cm diameter stainless steel tube. Cold helium gas flow provided by a dewar and helium transfer line was used to cool the exterior of the static mixer pump tube. Deuterium gas was mixed with helium gas through flow controllers at different concentrations while the composition of the exhaust gas was monitored with a Penning gauge and optical spectrometer to determine the effectiveness of the static mixer. It was found that with tube wall temperatures between 6 K and 9 K, the deuterium gas was completely cryopumped and only helium passed through the tube. These results have been used to design the cooling geometry and the static mixer pump tubes in the full-scale CVC prototype

  13. Evaluation of static mixer flow enhancements for cryogenic viscous compressor prototype for ITER vacuum system

    SciTech Connect

    Duckworth, Robert C.; Baylor, Larry R.; Meitner, Steven J.; Combs, Stephen K.; Ha, Tam; Morrow, Michael; Biewer, T. [Fusion and Materials for Nuclear System Division, Oak Ridge National Laboratory, Oak Ridge (United States); Rasmussen, David A.; Hechler, Michael P. [U.S. ITER Project Office, Oak Ridge National Laboratory, Oak Ridge (United States); Pearce, Robert J. H.; Dremel, Mattias [ITER Organization, 13115 St. Paul-lez-Durance (France); Boissin, J.-C. [Consultant, Grenoble (France)

    2014-01-29

    As part of the U.S. ITER contribution to the vacuum systems for the ITER fusion project, a cryogenic viscous compressor (CVC) is being designed and fabricated to cryopump hydrogenic gases in the torus and neutral beam exhaust streams and to regenerate the collected gases to controlled pressures such that they can be mechanically pumped with controlled flows to the tritium reprocessing facility. One critical element of the CVC design that required additional investigation was the determination of flow rates of the low pressure (up to 1000 Pa) exhaust stream that would allow for complete pumping of hydrogenic gases while permitting trace levels of helium to pass through the CVC to be pumped by conventional vacuum pumps. A sub-scale prototype test facility was utilized to determine the effectiveness of a static mixer pump tube concept, which consisted of a series of rotated twisted elements brazed into a 2-mm thick, 5-cm diameter stainless steel tube. Cold helium gas flow provided by a dewar and helium transfer line was used to cool the exterior of the static mixer pump tube. Deuterium gas was mixed with helium gas through flow controllers at different concentrations while the composition of the exhaust gas was monitored with a Penning gauge and optical spectrometer to determine the effectiveness of the static mixer. It was found that with tube wall temperatures between 6 K and 9 K, the deuterium gas was completely cryopumped and only helium passed through the tube. These results have been used to design the cooling geometry and the static mixer pump tubes in the full-scale CVC prototype.

  14. Centrifugo-dynamic inward pumping of liquids on a centrifugal microfluidic platform.

    PubMed

    Zehnle, Steffen; Schwemmer, Frank; Roth, Günter; von Stetten, Felix; Zengerle, Roland; Paust, Nils

    2012-12-21

    We present a method to pump liquids in a centrifugal microfluidic spinning disk from a radial outward position to a radial inward position. Centrifugal forces are applied to compress air in a cavity, this way storing pneumatic energy. The cavity is connected to an outlet channel having a lower hydraulic resistance compared to the inlet channel. The stored pneumatic energy is quickly released by fast reduction of rotational frequency. This way liquid is transported mainly through the channel with lower resistance, directing the liquid radially inwards. Pump efficiencies of >75% per pump cycle have been demonstrated for water, ethanol, a highly viscous lysis buffer and whole blood. By employing three pump cycles, water has been pumped radially inwards with an efficiency of >90%. The inward pumping requires centrifugation only, which is intrinsically available on every centrifugal microfluidic platform. PMID:23108455

  15. Alternative backing up pump for turbomolecular pumps

    DOEpatents

    Myneni, Ganapati Rao (Yorktown, VA)

    2003-04-22

    As an alternative to the use of a mechanical backing pump in the application of wide range turbomolecular pumps in ultra-high and extra high vacuum applications, palladium oxide is used to convert hydrogen present in the evacuation stream and related volumes to water with the water then being cryo-pumped to a low pressure of below about 1.e.sup.-3 Torr at 150.degree. K. Cryo-pumping is achieved using a low cost Kleemenco cycle cryocooler, a somewhat more expensive thermoelectric cooler, a Venturi cooler or a similar device to achieve the required minimization of hydrogen partial pressure.

  16. The effect of inlet swirl on the rotordynamic shroud forces in a centrifugal pump

    NASA Technical Reports Server (NTRS)

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

    1992-01-01

    The role played by fluid forces in determining the rotordynamic stability of a centrifugal pump is gaining increasing attention. The present research investigates the contributions to the rotordynamic forces from the discharge-to-suction leakage flows between the front shroud of the rotating impeller and the stationary pump casing. In particular, the dependency of the rotordynamic characteristics of leakage flows on the swirl at the inlet to the leakage path was examined. An inlet guide vane was designed for the experiment so that swirl could be introduced at the leakage flow inlet. The data demonstrates substantial rotordynamic effects and a destabilizing tangential force for small positive whirl ratios; this force decreased with increasing flow rate. The effect of swirl on the rotordynamic forces was found to be destabilizing.

  17. Comparison of the Gyro C1E3 and BioMedicus centrifugal pump performances during cardiopulmonary bypass.

    PubMed

    Nakazawa, T; Takami, Y; Makinouchi, K; Gay, J; Taylor, D; Ueyama, K; Ohashi, Y; Kawahito, K; Tayama, E; Glueck, J; Nosé, Y

    1997-07-01

    The compact eccentric inlet port (C1E3) centrifugal blood pump was developed as a cardiopulmonary bypass (CPB) pump. The C1E3 pump incorporated a sealless design with a blood stagnation free structure. The pump impeller was magnetically coupled to the driver magnet in a sealless manner. To develop an atraumatic and antithrombogenic centrifugal pump without a shaft seal junction, a double pivot bearing system was introduced. Recently, a mass production model of the C1E3 was fabricated and evaluated. The ratio of the normalized index of hemolysis (NIH) of the C1E3 was 0.007 g/ 100 L, in comparison to the NIH of the BP-80, 0.018 g/ 100 L, each in a CPB condition of 5 L/min against 325 mm Hg. Both pumps were compared in identical in vitro circuits. To further evaluate the pumps during cardiopulmonary bypass for reliability and function, 6 h of CPB was performed on each of 8 bovines using either the C1E3 or BP-80 centrifugal pump. The BP-80 and C1E3 provided pump flows of 50-60 ml/kg/min without incident. The hemodynamics were stable, and the hematology and biochemistry data were within normal ranges. There were no statistically significant differences between the 2 groups. Concerning the plasma free hemoglobin values, a mass production model of the C1E3 pump had the same hemolysis levels as the BP-80. Our preliminary studies reveal that the C1E3 pump is reliable. Also, the C1E3 will satisfy clinical requirements as a cardiopulmonary bypass pump. PMID:9212958

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

    NASA Astrophysics Data System (ADS)

    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-? 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.

  19. Insulin pump (image)

    MedlinePLUS

    The catheter at the end of the insulin pump is inserted through a needle into the abdominal ... with diabetes. Dosage instructions are entered into the pump's small computer and the appropriate amount of insulin ...

  20. Variable Frequency Pump Drives 

    E-print Network

    Karassik, I. J.; Petraccaro, L. L.; McGuire, J. T.

    1986-01-01

    VARIABLE FREQUENCY PUMP DRIVES Igor J. Karassik, L. L. Petraccaro &J. T. McGuire Worthington Pump Division, Dresser Industries Inc. Mountainside, N. J. Variable frequency drive represents a major milestone in the evolution of centrifugal...

  1. Simulation of operation modes of a centrifugal conductive magnetohydrodynamic pump

    NASA Astrophysics Data System (ADS)

    Katsnelson, S. S.; Pozdnyakov, G. A.

    2013-09-01

    A mathematical model of a centrifugal conductive magnetohydrodynamic (MHD) pump that calculates the distributions of velocity, current density, and pressure along the channel is developed. The viscous forces in the original system of MHD equations are taken into account on the basis of the known square law of the drag for a turbulent flow in a pipe, generalized for the case of plane flows in a channel. Dependences of the drag coefficient on the main governing parameters (metal flow rate, current intensity, and intensity of magnetic induction), which provide the agreement of the calculated and experimental data on the pressure at the pump outlet for different operation modes, are obtained. It is shown that these dependences have a universal character and the proposed model can be used to design pumps of this type and to manage their operation in production industry.

  2. Theory of plastic and viscous deformation

    NASA Astrophysics Data System (ADS)

    Alden, Thomas H.

    1987-06-01

    A theory of inelastic deformation, previously applied to 304 stainless steel with good quantitative agreement,2 is used to study a variety of materials which differ in the degree to which dislocation motion is resisted by viscous drag forces. In the theory, mobile dislocations are injected into the material by the rising stress, move over a mean free path to create strain, and are trapped. The velocity of motion, determined by the magnitude of an effective stress relative to the viscous drag, determines the mean lifetime of mobile dislocations and thereby, in part, the mobile density. An attractive feature of the theory is its simplicity. There are only three significant physical constants, two which characterize the dislocation velocity and one, taken in this case to be material independent, which determines the strain-hardening coefficient. The calculations have been done to simulate a variety of tests done in a soft tensile machine, in which the principal control is exerted over the rate of stress increase. The results show diverse transient strain rate behavior, determined by the magnitude of the drag forces, but a common steady state strain rate, controlled by strain hardening. Soft materials with low viscous drag, such as copper, exhibit brief transients on change of stress rate, whereas in hard materials with high drag, such as iron-3.5 pct silicon, the transients are very long. These transients include the onset of yielding at the start of a strain-stress test, low temperature creep, and the strain rate response to a brief pulse of high stress rate. Thus for example, hard materials show long loading transients (slow approach to steady state), extensive low temperature creep, and no evident ‘rapid’ strain during a high rate stress pulse. For soft materials the converse results obtain. These differences and others distinguish, respectively, viscous and plastic deformation behavior.

  3. Asymptotic Description of a Viscous Fluid Layer

    NASA Astrophysics Data System (ADS)

    Cerda, Enrique; Rojas, René; Tirapegui, Enrique

    2000-10-01

    We prove that the exact non local equation derived by the present authors for the temporal linear evolution of the surface of a viscous incompressible fluid reduces asymptotically for high viscosity to a second order Mathieu type equation proposed recently by Cerda and Tirapegui. The equation describes a strongly damped pendulum and the conditions of validity of the asymptotic regime are given in terms of the relevant physical parameters.

  4. Viscous fingering in non-Newtonian fluids

    Microsoft Academic Search

    Anke Lindner; Daniel Bonn; Eugenia Corvera Poiré; Martine Ben Amar; Jacques Meunier

    2002-01-01

    We study the viscous fingering or Saffman Taylor instability in two different dilute or semi-dilute polymer solutions. The different solutions exhibit only one non-Newtonian property, in the sense that other non-Newtonian effects can be neglected. The viscosity of solutions of stiff polymers has a strong shear rate dependence. Relative to Newtonian fluids, narrower fingers are found for rigid polymers. For

  5. Multiplicity scaling in ideal and viscous hydrodynamics

    Microsoft Academic Search

    Song Huichao; Ulrich Heinz

    2008-01-01

    Using numerical results from ideal and viscous relativistic hydrodynamic simulations with three different equations of state, for Au+Au and Cu+Cu collisions at different centralities and initial energy densities, we explore the dependence of the eccentricity-scaled elliptic flow, v\\/, and the produced entropy fraction, S\\/S, on the final charged hadron multiplicity density dN{sub ch}\\/dy per unit transverse overlap area S,(1\\/S)dN{sub ch}\\/dy.

  6. Dynamics of vortex rings in viscous fluids

    NASA Astrophysics Data System (ADS)

    Donnelly, Russell J.

    2010-03-01

    As part of a long range study of vortex rings, their dynamics, interactions with boundaries and with each other, we present the results of experiments on thin core rings generated by a piston gun in water. We characterize the dynamics of these rings by means of the traditional equations for such rings in an inviscid fluid suitably modifying them to be applicable to a viscous fluid. We develop expressions for the radius, core size, circulation, and bubble dimensions of these rings.

  7. Low thrust viscous nozzle flow fields prediction

    NASA Technical Reports Server (NTRS)

    Liaw, G. S.; Mo, J. D.

    1991-01-01

    A Navier-Stokes code was developed for low thrust viscous nozzle flow field prediction. An implicit finite volume in an arbitrary curvilinear coordinate system lower-upper (LU) scheme is used to solve the governing Navier-Stokes equations and species transportation equations. Sample calculations of carbon dioxide nozzle flow are presented to verify the validity and efficiency of this code. The computer results are in reasonable agreement with the experimental data.

  8. Variable Frequency Pump Drives

    E-print Network

    Karassik, I. J.; Petraccaro, L. L.; McGuire, J. T.

    VARIABLE FREQUENCY PUMP DRIVES Igor J. Karassik, L. L. Petraccaro &J. T. McGuire Worthington Pump Division, Dresser Industries Inc. Mountainside, N. J. Variable frequency drive represents a major milestone in the evolution of centrifugal... pumps and their application. The fundamentals of variable speed centrifugal pump operation are reviewed, then the advantages and evaluation approaches peculiar to variable frequency drive outlined. In addition to the immediate advantages available...

  9. Nonisothermal viscous sintering of volcanic ash

    NASA Astrophysics Data System (ADS)

    Wadsworth, Fabian B.; Vasseur, Jérémie; Aulock, Felix W.; Hess, Kai-Uwe; Scheu, Bettina; Lavallée, Yan; Dingwell, Donald B.

    2014-12-01

    Volcanic ash is often deposited in a hot state. Volcanic ash containing glass, deposited above the glass transition interval, has the potential to sinter viscously both to itself (particle-particle) and to exposed surfaces. Here we constrain the kinetics of this process experimentally under nonisothermal conditions using standard glasses. In the absence of external load, this process is dominantly driven by surface relaxation. In such cases the sintering process is rate limited by the melt viscosity, the size of the particles and the melt-vapor interfacial tension. We propose a polydisperse continuum model that describes the transition from a packing of particles to a dense pore-free melt and evaluate its efficacy in describing the kinetics of volcanic viscous sintering. We apply our model to viscous sintering scenarios for cooling crystal-poor rhyolitic ash using the 2008 eruption of Chaitén volcano as a case example. We predict that moderate linear cooling rates of > 0.1°C min-1 can result in the common observation of incomplete sintering and the preservation of pore networks.

  10. Viscous Glass Sealants for SOFC Applications

    SciTech Connect

    Scott Misture

    2012-09-30

    Two series of silicate glasses that contain gallium as the primary critical component have been identified and optimized for viscous sealing of solid oxide fuel cells operating from 650 to 850°C. Both series of glass sealants crystallize partially upon heat treatment and yield multiphase microstructures that allow viscous flow at temperatures as low as 650°C. A fully amorphous sealant was also developed by isolating, synthesizing and testing a silicate glass of the same composition as the remnant glassy phase in one of the two glass series. Of ~40 glasses tested for longer than 500 hours, a set of 5 glasses has been further tested for up to 1000h in air, wet hydrogen, and against both yttria-stabilized zirconia and aluminized stainless steel. In some cases the testing times reached 2000h. The reactivity testing has provided new insight into the effects of Y, Zr, and Al on bulk and surface crystallization in boro-gallio-silicate glasses, and demonstrated that at least 5 of the newly-developed glasses are viable viscous sealants.

  11. Sampling pump with packer

    Microsoft Academic Search

    K. L. Niehaus; D. A. Fischer

    1993-01-01

    A groundwater sampling apparatus is described for withdrawing groundwater samples from a groundwater monitoring well, the apparatus having dedicatable inground components to prevent the apparatus from contaminating another well, the apparatus comprising: a pump adapted to be submerged in the groundwater within the well for pumping a portion of the groundwater, the pump being permanently dedicatable to the well and

  12. Rotary magnetic heat pump

    DOEpatents

    Kirol, L.D.

    1987-02-11

    A rotary magnetic heat pump constructed without flow seals or segmented rotor accomplishes recuperation and regeneration by using split flow paths. Heat exchange fluid pumped through heat exchangers and returned to the heat pump splits into two flow components: one flowing counter to the rotor rotation and one flowing with the rotation. 5 figs.

  13. Pump for Saturated Liquids

    NASA Technical Reports Server (NTRS)

    Elliott, D. G.

    1986-01-01

    Boiling liquids pumped by device based on proven components. Expanding saturated liquid in nozzle and diverting its phases along separate paths in liquid/vapor separator raises pressure of liquid. Liquid cooled in process. Pump makes it unnecessary to pressurize cryogenic liquids in order to pump them. Problems of introducing noncondensable pressurizing gas avoided.

  14. Heat pumps in distillation

    Microsoft Academic Search

    1976-01-01

    The methods used and results obtained in evaluating the economics of substituting heat pumps for conventional distillation process design are presented. From this study it was concluded that: heat pumps have extensive applicability to distillation whenever direct refrigeration or chilled water are required for condensation; heat pumps have limited, but very real ranges of applicability when reboiler temperatures are above

  15. Rotary magnetic heat pump

    DOEpatents

    Kirol, Lance D. (Shelly, ID)

    1988-01-01

    A rotary magnetic heat pump constructed without flow seals or segmented rotor accomplishes recuperation and regeneration by using split flow paths. Heat exchange fluid pumped through heat exchangers and returned to the heat pump splits into two flow components: one flowing counter to the rotor rotation and one flowing with the rotation.

  16. Well pump controller

    Microsoft Academic Search

    Pikna

    1985-01-01

    A device for automatically controlling the pumping of fluids from a well of the type using a walking beam and positive displacement pump to provide efficient utilization of the pumping equipment and energy required therefor, and to obtain efficient flow rates from the wall. A sensor detects the position of the walking beam at a predetermined position on the up-stroke

  17. Multiwell pumping device

    SciTech Connect

    Dysarz, E.D.

    1987-06-30

    This patent describes a balanced pumping apparatus for pumping two laterally spaced wells comprising: a left conductor on a left well; a right conductor on a right the well; a left pump casing inside the well conductor; a right pump casing inside the right well conductor; a left sucker rod inside the left pump casing; a right sucker rod inside the right pump casing; flexible linkage means for attachment to the top ends of the right sucker rod and left sucker rod; a drive motor with a rotating shaft; a drive sprocket rotatably engaging the flexible linkage means; a separate pump casing flange attached to the upper section of each well conductors; a separate upper flange attached to the upper section of each pump casing and positioned at an axial location above the point attached to the pump casing; a separate transition piece attached to the top of each pump casing flange; a separate pump support attached to the top of each transition piece; a plate-like structural support means placed in a vertical plane above the well conductors and supporting the drive motor, the drive sprocket, the flexible linkage means, and the sucker rods; a structural load transfer means connecting the plate-like structural support means to the well conductors; a motor control unit for supporting itself and controlling the drive motor; and a separate shaft extending across each pump support.

  18. Numerical simulation and analysis of power consumption and Metzner-Otto constant for impeller of 6PBT

    NASA Astrophysics Data System (ADS)

    Luan, Deyu; Chen, Qiao; Zhou, Shenjie

    2014-05-01

    Majority of non-Newtonian fluids are pseudoplastic with shear-thinning property, which means that the viscosity will be different in different parts of the stirred tank. In such mixing process, it is difficult to predict accurately the power consumption and mean shear rate for designing novel impeller. Metzner-Otto method is a widely accepted method to solve these questions in mixing non-Newtonian fluids. As a result, Metzner-Otto constant will become a key factor to achieve an optimum way of economical mixing. In this paper, taking glycerine and xanthan gum solutions as research system, the power consumption, stirred by the impeller composed of perturbed six-bent-bladed turbine (6PBT) with differently geometrical characteristics in a cylindrical vessel, is studied by means of computational fluid dynamics (CFD). The flow is modeled as laminar and a multiple reference frame (MRF) approach is used to solve the discretized equations of motion. In order to determine the capability of CFD to forecast the flow process, the torque test experiment is used to measure the glycerine solution power consumption. The rheological properties of the xanthan gum solutions are determined by a Brookfield rheometer. It is observed that the power consumption predicted by numerical simulation agrees well with those measured using torque experiment method in stirring glycerine solution, which validate the numerical model. Metzner-Otto constant is almost not correlated with the flow behavior index of pseudoplastic fluids. This paper establishes the complete correlations of power constant and Metzner-Otto constant with impeller geometrical characteristics through linear regression analysis, which provides the valuable instructions and references for accurately predicting the power consumption and mean shear rate of pseudoplastic fluids in laminar flow, comparatively.

  19. AOFA- THREE-DIMENSIONAL SUPERSONIC VISCOUS FLOW

    NASA Technical Reports Server (NTRS)

    Rakich, J. V.

    1994-01-01

    This program, which is called 'AOFA', determines the complete viscous and inviscid flow around a body of revolution at a given angle of attack and traveling at supersonic speeds. The viscous calculations from this program agree with experimental values for surface and pitot pressures and with surface heating rates. At high speeds, lee-side flows are important because the local heating is difficult to correlate and because the shed vortices can interact with vehicle components such as a canopy or a vertical tail. This program should find application in the design analysis of any high speed vehicle. Lee-side flows are difficult to calculate because thin-boundary-layer theory is not applicable and the concept of matching inviscid and viscous flow is questionable. This program uses the parabolic approximation to the compressible Navier-Stokes equations and solves for the complete inviscid and viscous regions of flow, including the pressure. The parabolic approximation results from the assumption that the stress derivatives in the streamwise direction are small in comparison with derivatives in the normal and circumferential directions. This assumption permits the equation to be solved by an implicit finite difference marching technique which proceeds downstream from the initial data point, provided the inviscid portion of flow is supersonic. The viscous cross-flow separation is also determined as part of the solution. To use this method it is necessary to first determine an initial data point in a region where the inviscid portion of the flow is supersonic. Input to this program consists of two parts. Problem description is conveyed to the program by namelist input. Initial data is acquired by the program as formatted data. Because of the large amount of run time this program can consume the program includes a restart capability. Output is in printed format and magnetic tape for further processing. This program is written in FORTRAN IV and has been implemented on a CDC 7600 with a central memory requirement of approximately 35K (octal) of 60 bit words.

  20. The PediPump: a versatile, implantable pediatric ventricular assist device--update IV.

    PubMed

    Duncan, Brian W; Fukamachi, Kiyotaka; Noble, Lawrence D; Dudzinski, David T; Flick, Christine R; Fumoto, Hideyuki; Shiose, Akira; Arakawa, Yoko; Takaseya, Tohru; Casas, Fernando; Smith, William A

    2009-11-01

    Cleveland Clinic's PediPump (Cleveland, OH, USA) is a ventricular assist device designed for the support of pediatric patients. The PediPump is a mixed-flow ventricular assist device with a magnetically suspended impeller measuring 10.5 mm in diameter by 64.5 mm in length. Progress and achievements for the PediPump program are considered according to the development project's three primary objectives: Basic engineering: along with size reductions, substantial design improvements have been incorporated in each design iteration including the motor, magnetic bearings, axial touch points, and heat transfer path; Anatomic modeling and device fitting studies: Techniques based on computed tomography and magnetic resonance imaging have been developed to create three-dimensional anatomic-modeling and device-fitting tools to facilitate device implantation and to assist in preoperative planning. For in vivo testing, to date, six acute (6-h duration) and nine chronic (30-day target duration) implantations have been performed in sheep; the implantation of the PediPump appears to be relatively easy with excellent hemodynamic performance and minimal hemolysis during support. Cleveland Clinic's PediPump program supported by the National Heart, Lung and Blood Institute's Pediatric Circulatory Support Program has led to the development of a pediatric ventricular assist device that has satisfactory performance in preclinical evaluation and appears to be ready to support a program of clinical testing. PMID:20050296

  1. Experimental testing of centrifugal pump: small and medium sized enterprise product

    NASA Astrophysics Data System (ADS)

    Ismail, R.; Paddiyatu, F.; Khafidh, M.; Nugroho, S.; Sugiyanto, S.; Jamari, J.

    2014-06-01

    This paper reports the experimental testing for centrifugal pump for fisherman ship, manufactured by small and medium sized enterprises in Central Java Province, Indonesia. The research covers material analysis, component observation, endurance and vibration test. Six centrifugal pumps are tested and three main pump components are discussed: shaft, bearings and seals. The results show that the material of the shaft is predicted to support and transmit the load from the engine to impeller. The problem found in the tolerance and geometry accuracy of the shaft which causes difficulties during assembling process, excessive wear and leakage during testing. From the endurance and vibration test, the ball bearings fail and lock the shaft due to the fatigue on the rolling elements and raceways. The oil seal and water seal also fail in maintaining the oil and water in the chamber and induce the unlubricated system for the ball bearings. Some suggestions are delivered to improve the product quality of the centrifugal pump. A good quality of the centrifugal pump for fishermen ship and long life span is expected to be produced by local SMEs to win the free trade competition in the Indonesian market.

  2. Magnetic drive system for a new centrifugal rotary blood pump.

    PubMed

    Hilton, Andrew; Tansley, Geoff

    2008-10-01

    The purpose of this investigation was to design a novel magnetic drive and bearing system for a new centrifugal rotary blood pump (CRBP). The drive system consists of two components: (i) permanent magnets within the impeller of the CRBP; and (ii) the driving electromagnets. Orientation of the magnets varies from axial through to 60 degrees included out-lean (conical configuration). Permanent magnets replace the electromagnet drive to allow easier characterization. The performance characteristics tested were the axial force of attraction between the stator and rotor at angles of rotational alignment, Ø, and the corresponding torque at those angles. The drive components were tested for various magnetic cone angles, theta. The test was repeated for three backing conditions: (i) non-backed; (ii) steel-cupped; and (iii) steel plate back-iron, performed on an Instron tensile testing machine. Experimental results were expanded upon through finite element and boundary element analysis (BEM). The force/torque characteristics were maximal for a 12-magnet configuration at 0 degree cone angle with steel-back iron (axial force = 60 N, torque = 0.375 Nm). BEM showed how introducing a cone angle increases the radial restoring force threefold while not compromising axial bearing force. Magnets in the drive system may be orientated not only to provide adequate coupling to drive the CRBP, but to provide significant axial and radial bearing forces capable of withstanding over 100 m/s(2) shock excitation on the impeller. Although the 12 magnet 0 degree (theta) configuration yielded the greatest force/torque characteristic, this was seen as potentially unattractive as this magnetic cone angle yielded poor radial restoring force characteristics. PMID:18959665

  3. Liquid metal electric pump

    DOEpatents

    Abbin, Joseph P. (Albuquerque, NM); Andraka, Charles E. (Albuquerque, NM); Lukens, Laurance L. (Albuquerque, NM); Moreno, James B. (Albuquerque, NM)

    1992-01-01

    An electrical pump for pumping liquid metals to high pressures in high temperature environments without the use of magnets or moving mechanical parts. The pump employs a non-porous solid electrolyte membrane, typically ceramic, specific to the liquid metal to be pumped. A DC voltage is applied across the thickness of the membrane causing ions to form and enter the membrane on the electrically positive surface, with the ions being neutralized on the opposite surface. This action provides pumping of the liquid metal from one side of the non-porous solid electrolyte membrane to the other.

  4. Liquid metal electric pump

    DOEpatents

    Abbin, J.P.; Andraka, C.E.; Lukens, L.L.; Moreno, J.B.

    1992-01-14

    An electrical pump for pumping liquid metals to high pressures in high temperature environments without the use of magnets or moving mechanical parts. The pump employs a non-porous solid electrolyte membrane, typically ceramic, specific to the liquid metal to be pumped. A DC voltage is applied across the thickness of the membrane causing ions to form and enter the membrane on the electrically positive surface, with the ions being neutralized on the opposite surface. This action provides pumping of the liquid metal from one side of the non-porous solid electrolyte membrane to the other. 3 figs.

  5. Jet pump assisted artery

    NASA Technical Reports Server (NTRS)

    1975-01-01

    A procedure for priming an arterial heat pump is reported; the procedure also has a means for maintaining the pump in a primed state. This concept utilizes a capillary driven jet pump to create the necessary suction to fill the artery. Basically, the jet pump consists of a venturi or nozzle-diffuser type constriction in the vapor passage. The throat of this venturi is connected to the artery. Thus vapor, gas, liquid, or a combination of the above is pumped continuously out of the artery. As a result, the artery is always filled with liquid and an adequate supply of working fluid is provided to the evaporator of the heat pipe.

  6. Viscous dark energy and generalized second law of thermodynamics

    E-print Network

    M. R. Setare; A. Sheykhi

    2011-03-05

    We examine the validity of the generalized second law of thermodynamics in a non-flat universe in the presence of viscous dark energy. At first we assume that the universe filled only with viscous dark energy. Then, we extend our study to the case where there is an interaction between viscous dark energy and pressureless dark matter. We examine the time evolution of the total entropy, including the entropy associated with the apparent horizon and the entropy of the viscous dark energy inside the apparent horizon. Our study show that the generalized second law of thermodynamics is always protected in a universe filled with interacting viscous dark energy and dark matter in a region enclosed by the apparent horizon. Finally, we show that the the generalized second law of thermodynamics is fulfilled for a universe filled with interacting viscous dark energy and dark matter in the sense that we take into account the Casimir effect.

  7. CFD analysis on a turbulence generator of medium consistency pump

    NASA Astrophysics Data System (ADS)

    Ma, X. D.; Wu, D. Z.; Huang, D. S.; Yu, H.; Wang, L. Q.

    2013-12-01

    Medium concentration paper suspension is a water-air-fibre three phase suspension. It has complicated physical features. When concentration exceeds 7%, it stops flowing and acts like a solid. A generator suspension is installed before the impeller to disturb the flocs and networks to make it start to flow. In this paper, CFD method is adopted to study the effects of the turbulence generator. As there is not a mature model to describe the characteristic of pulp suspension, Newtonian fluid is used to get the general property of the turbulence generator. In the CFD simulation, apparent viscosity of the pulp suspension is used to characterize the mixture. Firstly, numerical method is applied to get the turbulence generator properties in different rotational speed and different viscosity. From another point of view, air contained in the suspension is separate initially by means of centrifugal force. As it is difficult to describe a practical model of pulp suspension, it is simplified to be a water-air two-phase mixture. Several air contents are simulated to study the air distribution in the turbulence generator. The results show that there are three main effects of turbulence generator. Firstly, it has an entrainment effect of the suspension to make it into the pump. Secondly, it stirs the pulp suspension to bring it into flowing. Last, air is centralized in the shaft centre and pre-separated in the turbulence generator. So, the turbulence generator can pre-treat the pulp suspension to make the MC pump transport suspension successfully.

  8. a Hybrid Spectral\\/finite Volume Method for Viscous Flows

    Microsoft Academic Search

    T. Minyard; Y. Kallinderis

    1995-01-01

    This paper presents a hybrid spectral\\/finite volume method for steady-state compressible viscous flows. The method is evaluated for accuracy via test cases for various Mach numbers. The domain is divided into a viscous region and an inviscid region. The viscous region uses the full Navier-Stokes equations, while the inviscid region employs the Euler equations. A high order Chebyshev collocation spectral

  9. Viscous damping of Alfven surface waves in the solar atmosphere

    SciTech Connect

    Rathinavelu, G. D.; Sivaraman, M. [Gandhigram Rural University, Plasma Physics Group, Department of Physics (India); Narayanan, A. S. [Indian Institute of Astrophysics (India)

    2009-11-15

    The dispersion relation for the propagation of viscous Alfven surface waves along viscous plasmaplasma interface has been derived. Two modes of Alfven surface waves are found to propagate with their characteristics depend on the interface parameters like magnetic field, density ratio, viscosity, etc. The viscous damping of Alfven surface waves has been studied in the astrophysical point of view. The damping length of Alfven surface waves due to viscosity in the solar atmosphere has been estimated.

  10. Direct photon production from viscous quark-gluon plasma

    Microsoft Academic Search

    A. K. Chaudhuri; Bikash Sinha

    2011-01-01

    We simulate direct photon production in the evolution of viscous quark-gluon plasma medium. Photons from Compton and annihilation processes are considered. The viscous effect on photon production is very strong and reliable simulation is possible only in a limited pT range. For minimally viscous fluid (eta\\/s=0.08), direct photons can be reliably computed only up to pT<=1.3 GeV. With reduced viscosity

  11. Direct photon production from viscous quark-gluon plasma

    Microsoft Academic Search

    A. K. Chaudhuri; Bikash Sinha

    2011-01-01

    We simulate direct photon production in the evolution of viscous quark-gluon plasma medium. Photons from Compton and annihilation processes are considered. The viscous effect on photon production is very strong and reliable simulation is possible only in a limited p{sub T} range. For minimally viscous fluid (\\/s=0.08), direct photons can be reliably computed only up to p{sub T}{<=}1.3 GeV. With

  12. Computation of weakly-compressible highly-viscous liquid flows

    Microsoft Academic Search

    M. F. Webster; I. J. Keshtiban; F. Belblidia

    2004-01-01

    We introduce a second-order accurate time-marching pressure-correction algorithm to accommodate weakly-compressible highly-viscous liquid flows at low Mach number. As the incompressible limit is approached (Ma ? 0), the consistency of the compressible scheme is highlighted in recovering equivalent incompressible solutions. In the viscous-dominated regime of low Reynolds number (zone of interest), the algorithm treats the viscous part of the equations

  13. Viscous damping of Alfvén surface waves at a magnetic interface

    NASA Astrophysics Data System (ADS)

    Rathinavelu, G. David; Sivaraman, M.; Narayanan, A. Satya

    2010-02-01

    The dispersion relation for the propagation of viscous Alfvén surface waves along viscous plasma-plasma interface has been derived. Two modes of Alfvén surface waves are found to propagate with their characteristics depend on the interface parameters like magnetic field, density ratio, viscosity....etc. The viscous damping of Alfvén surface waves has been studied in the astrophysical point of view. The damping length of Alfvén surface waves due to viscosity in the solar atmosphere has been estimated.

  14. Pumping behavior of sputtering ion pump

    SciTech Connect

    Chou, T.S.; Bittner, J.; Schuchman, J.

    1991-12-31

    To optimize the design of a distributed ion pump (DIP) for the Superconducting X-Ray Lithography Source (SXLS) the stability of the rotating electron cloud at very high magnetic field beyond transition, must be re-examined. In this work the pumping speed and frequency spectrum of a DIP at various voltages (1 to 10 KV) and various magnetic fields (0.1 to 4 Tesla) are measured. Three cell diameters 10 mm, 5 mm and 2.5 mm, each 8 mm long, and with 3 or 4 mm gaps between anode and cathode are investigated. In this study both the titanium cathodes and the stainless steel anode plates are perforated with holes comparable in size to the anode cell diameters. Only the partially saturated pumping behavior is under investigation. The ultimate pressure and conditioning of the pump will be investigated at a later date when the stability criterion for the electron cloud is better understood.

  15. Pumping behavior of sputtering ion pump

    SciTech Connect

    Chou, T.S.; Bittner, J.; Schuchman, J.

    1991-01-01

    To optimize the design of a distributed ion pump (DIP) for the Superconducting X-Ray Lithography Source (SXLS) the stability of the rotating electron cloud at very high magnetic field beyond transition, must be re-examined. In this work the pumping speed and frequency spectrum of a DIP at various voltages (1 to 10 KV) and various magnetic fields (0.1 to 4 Tesla) are measured. Three cell diameters 10 mm, 5 mm and 2.5 mm, each 8 mm long, and with 3 or 4 mm gaps between anode and cathode are investigated. In this study both the titanium cathodes and the stainless steel anode plates are perforated with holes comparable in size to the anode cell diameters. Only the partially saturated pumping behavior is under investigation. The ultimate pressure and conditioning of the pump will be investigated at a later date when the stability criterion for the electron cloud is better understood.

  16. Tandem pump assembly

    SciTech Connect

    Dzioba, D.L.

    1986-05-06

    In combination, an engine having an oil pan containing oil at a certain level, a tandem pump arrangement is described mounted in the oil pan, the pump arrangement comprising an oil pump for delivering the oil under pressure to lubricate the engine and a vacuum pump for establishing a vacuum, the oil pump having two meshing gears of different pitch diameter adapted to produce oil pumping action by their meshing engagement upon drive to the one gear having the larger pitch diameter and the drive thereby of the other gear having the smaller pitch diameter at a higher speed, drive means for connecting the engine to drive the one gear. The vacuum pump has an input connected to be driven by the other gear whereby the vacuum pump is driven through the the oil pump at increased speed with an overdrive ratio determined by the ratio of the pitch diameters of the gears, the vacuum pump being lubricated by the oil in the oil pan and having an exhaust line exiting in the oil pan above the oil level so as to ensure return of such oil to the oil pan.

  17. Viscous contributions to the pressure for potential flow analysis of capillary instability of two viscous fluids

    E-print Network

    Joseph, Daniel D.

    and that of surrounding air on the stability of a columnar jet. The effect of viscosity on the stability of a liquid is analyzed using viscous potential flow. An effect of viscosity on the irrotational motion may be introduced proportional to velocity. The effect of viscosity is treated in the special case in which the viscosity is so

  18. Wall reflection of a viscous vortex ring

    NASA Technical Reports Server (NTRS)

    Sa, J. Y.; Chang, K. S.; Liu, C. H.

    1986-01-01

    The behavior of a viscous axisymmetric vortex ring being reflected from a wall is investigated. The incompressible Navier-Stokes equations formulated in terms of the vorticity function and vector potential are numerically integrated by implicit finite difference methods. To specify the vector potential at a far boundary from the wall, the existing integral method used so far only for an unbounded domain is modified by a kind of image method. The trajectory of the vortex ring calcualted as a result closely resembles that observable from the experiment.

  19. Non-perturbative reorganization of viscous hydrodynamics

    NASA Astrophysics Data System (ADS)

    Strickland, Michael

    2014-09-01

    The quark-gluon plasma created in relativistic heavy ion collisions is not momentum-space isotropic in the local rest frame due to the rapid longitudinal expansion of the system. As a result, the system's pressure transverse to the beam line can be significantly different than the pressure along the beamline. Such large pressure anisotropies (related to large shear corrections) can cause severe problems for traditional viscous hydrodynamics approaches and result in e.g. negative one-particle distribution functions, negative particle pressures, etc. In this talk, I will review a recently developed framework that builds in such momentum-space anisotropies non-perturbatively at leading order and then treats deviations perturbatively. The resulting framework has been dubbed anisotropic hydrodynamics (aHydro). The aHydro framework has many nice features, e.g. (i) it has been shown that aHydro agrees with traditional viscous hydrodynamics in the limit of small anisotropies (near equilibrium), (ii) it can be used to describe the large viscosity limit in which the system is free streaming and far-from-equilibrium, (iii) it is guaranteed that the leading-order one-particle distribution and longitudinal pressure are positive, both at small and large anisotropy. The quark-gluon plasma created in relativistic heavy ion collisions is not momentum-space isotropic in the local rest frame due to the rapid longitudinal expansion of the system. As a result, the system's pressure transverse to the beam line can be significantly different than the pressure along the beamline. Such large pressure anisotropies (related to large shear corrections) can cause severe problems for traditional viscous hydrodynamics approaches and result in e.g. negative one-particle distribution functions, negative particle pressures, etc. In this talk, I will review a recently developed framework that builds in such momentum-space anisotropies non-perturbatively at leading order and then treats deviations perturbatively. The resulting framework has been dubbed anisotropic hydrodynamics (aHydro). The aHydro framework has many nice features, e.g. (i) it has been shown that aHydro agrees with traditional viscous hydrodynamics in the limit of small anisotropies (near equilibrium), (ii) it can be used to describe the large viscosity limit in which the system is free streaming and far-from-equilibrium, (iii) it is guaranteed that the leading-order one-particle distribution and longitudinal pressure are positive, both at small and large anisotropy. DOE Grant No. DE SC0004104.

  20. Dissipative hydrodynamics for viscous relativistic fluids

    E-print Network

    Ulrich W. Heinz; Huichao Song; Asis K. Chaudhuri

    2005-10-04

    Explicit equations are given for describing the space-time evolution of non-ideal (viscous) relativistic fluids undergoing boost-invariant longitudinal and arbitrary transverse expansion. The equations are derived from the second-order Israel-Stewart approach which ensures causal evolution. Both azimuthally symmetric (1+1)-dimensional and non-symmetric (2+1)-dimensional transverse expansion are discussed. The latter provides the formal basis for the hydrodynamic computation of elliptic flow in relativistic heavy-ion collisions including dissipative effects.

  1. Causal relativistic hydrodynamics for viscous fluids

    E-print Network

    Ulrich W Heinz; Huichao Song

    2008-06-03

    We report on recent results from VISH2+1, a code that solves the relativistic Israel-Stewart equations for causal viscous hydrodynamics for heavy-ion collisions with longitudinal boost invariance. We find that even ``minimal'' shear viscosity eta/s=hbar/(4pi) leads to a large reduction of elliptic flow compared to ideal fluid dynamics. We explore systematically the sensitivity of this reduction to the equation of state, system size, initial conditions, and the microscopic relaxation time in different formulations of the Israel-Stewart equations.

  2. Motility of flagellated bacteria in viscous environments.

    PubMed Central

    Greenberg, E P; Canale-Parola, E

    1977-01-01

    The lowest viscosity that immobilized flagellated bacteria such as Psedomonas aeruginosa, Spirillum serpens, and Escherichia coli was 60 centipoise (cp). Much higher viscosities (1,000 cp and higher) were required to immobilize two flagellated bacteria selectively isolated from nature by methods based on their ability to migrate through agar gels. The latter finding indicates that certain flagellated bacteria have the ability to swim through environments of relatively high viscosity. It is suggested that these flagellated bacteria possess a specialized type of motility apparatus suited to viscous conditions present in their habitats. PMID:410784

  3. Multigrid Approach to Incompressible Viscous Cavity Flows

    NASA Technical Reports Server (NTRS)

    Wood, William A.

    1996-01-01

    Two-dimensional incompressible viscous driven-cavity flows are computed for Reynolds numbers on the range 100-20,000 using a loosely coupled, implicit, second-order centrally-different scheme. Mesh sequencing and three-level V-cycle multigrid error smoothing are incorporated into the symmetric Gauss-Seidel time-integration algorithm. Parametrics on the numerical parameters are performed, achieving reductions in solution times by more than 60 percent with the full multigrid approach. Details of the circulation patterns are investigated in cavities of 2-to-1, 1-to-1, and 1-to-2 depth to width ratios.

  4. Solving the viscous hydrodynamics order by order

    E-print Network

    Gao, Jian-Hua

    2014-01-01

    In this paper, we propose a method of solving the viscous hydrodynamics order by order in a derivative expansion. In such method, the zero order solution is just the one of the ideal hydrodynamics. All the other higher order corrections satisfy the same first-order partial differential equations but with different inhomogeneous terms. We therefore argue that our method could be easily extended to any orders. The problem of causality and stability will be released if the gradient expansion is guaranteed. This method might be of great help to both theoretical and numerical calculations of relativistic hydrodynamics.

  5. Simulation Of Unsteady, Viscous, Incompressible Flow

    NASA Technical Reports Server (NTRS)

    Rosenfeld, Moshe; Kwak, Dochan

    1990-01-01

    Method for numerical solution of Navier-Stokes equations of viscous, incompressible flow developed based on use of fractional-step procedure. Accurate to second order in both space and time. Attempt made to minimize Poisson-equation difficulties by choosing pressures at centers and volume fluxes across faces of computational cells as dependent variables instead of familiar Cartesian components of velocity. Choice ensures satisfaction of discrete equation of conservation of mass to within round-off errors in any coordinate system and has favorable effects on convergence properties.

  6. Numerical methods for inviscid/viscous flows

    NASA Technical Reports Server (NTRS)

    El-Mistikawy, T. M.; Werle, M. J.

    1977-01-01

    A study of numerical schemes for solving viscous fluid flow problems with sizable regions of predominantly inviscid flow is presented. Difficulties associated with the familiar central difference approach for such problems were analyzed and alternative finite difference approaches employing windward concepts are presented. In addition, difference relations based on exponential operators were developed. All such schemes were demonstrated and evaluated through application to the case of Falkner Skan flow with blowing - a problem in which a sizable region of predominantly inviscid flow develops near the injection surface that traditionally causes numerical difficulty.

  7. Pump isolation valve

    DOEpatents

    Kinney, Calvin L. (Penn Hills, PA); Wetherill, Todd M. (Lower Burrell, PA)

    1983-08-02

    The pump isolation valve provides a means by which the pump may be selectively isolated from the remainder of the coolant system while being compatible with the internal hydraulic arrangement of the pump during normal operation of the pump. The valve comprises a valve cylinder disposed around the pump and adjacent to the last pump diffuser with a turning vane attached to the lower end of the valve cylinder in a manner so as to hydraulically match with the discharge diffuser. The valve cylinder is connected to a drive means for sliding the valve cylinder relative to the diffuser support cylinder so as to block flow in either direction through the discharge diffuser when the valve is in the closed position and to aid in the flow of the coolant from the discharge diffuser by means of the turning vane when the valve is in the open position.

  8. Piezoelectric hydraulic pump performance

    NASA Astrophysics Data System (ADS)

    Mauck, Lisa D.; Oates, William S.; Lynch, Christopher S.

    2001-06-01

    A piezohydraulic pump making use of the step and repeat capability of piezoelectric actuators has been developed for actuation of aircraft control surfaces. The piezohydraulic pump utilizes a piezoelectric stack actuator to drive a piston in a cylinder. The cylinder is fitted with two check valves. On the compression stroke, oil is forced out of the cylinder. On the intake stroke, oil is drawn into the cylinder. The oil is used to drive a linear actuator. The actuator was driven at 7cm/sec with a 271N (61lb) blocking force. To achieve this, the piezoelectric stack actuator was driven at 60Hz with a switching power supply. The system utilizes an accumulator to eliminate cavitation. This work discusses piezohydraulic pumping theory, pump design, and pump performance. Consideration of pump performance includes the effects of varying accumulator pressure, hydraulic oil viscosity, and load imposed on the linear actuator.

  9. Minimize pump downtime

    Microsoft Academic Search

    1995-01-01

    In refineries and petrochemical plants, centrifugal pumps usually lead the list of equipment that is most susceptible to failure. Using guidelines, maintenance mechanics can improve troubleshooting methods when investigating pump bedplates, underlying concrete foundations and grouting problems. Too often, mechanics may improperly diagnose a misalignment--caused by grouting problems--as an unbalance or a bearing-wearing problem when troubleshooting pump failure. Result: bearing,

  10. Detection of pump degradation

    SciTech Connect

    Greene, R.H.; Casada, D.A.; Ayers, C.W. [and others

    1995-08-01

    This Phase II Nuclear Plant Aging Research study examines the methods of detecting pump degradation that are currently employed in domestic and overseas nuclear facilities. This report evaluates the criteria mandated by required pump testing at U.S. nuclear power plants and compares them to those features characteristic of state-of-the-art diagnostic programs and practices currently implemented by other major industries. Since the working condition of the pump driver is crucial to pump operability, a brief review of new applications of motor diagnostics is provided that highlights recent developments in this technology. The routine collection and analysis of spectral data is superior to all other technologies in its ability to accurately detect numerous types and causes of pump degradation. Existing ASME Code testing criteria do not require the evaluation of pump vibration spectra but instead overall vibration amplitude. The mechanical information discernible from vibration amplitude analysis is limited, and several cases of pump failure were not detected in their early stages by vibration monitoring. Since spectral analysis can provide a wealth of pertinent information concerning the mechanical condition of rotating machinery, its incorporation into ASME testing criteria could merit a relaxation in the monthly-to-quarterly testing schedules that seek to verify and assure pump operability. Pump drivers are not included in the current battery of testing. Operational problems thought to be caused by pump degradation were found to be the result of motor degradation. Recent advances in nonintrusive monitoring techniques have made motor diagnostics a viable technology for assessing motor operability. Motor current/power analysis can detect rotor bar degradation and ascertain ranges of hydraulically unstable operation for a particular pump and motor set. The concept of using motor current or power fluctuations as an indicator of pump hydraulic load stability is presented.

  11. Heat pump advances

    Microsoft Academic Search

    1989-01-01

    This article describes new heat pump units that offer increased comfort as well as energy savings. Hydrotech 2000, a high-efficiency air-source heat pump developed by Carrier Corporation and the Electric Power Research Institute, combines domestic water heating with air conditioning; in addition, the system's compressor and blower use variable-speed motors. This reduces electric consumption by matching the heat pump's output

  12. Distribution of a viscous binder during high shear granulation--sensitivity to the method of delivery and its impact on product properties.

    PubMed

    Tan, Bernice Mei Jin; Loh, Zhi Hui; Soh, Josephine Lay Peng; Liew, Celine Valeria; Heng, Paul Wan Sia

    2014-01-01

    Binder distribution in the powder mass during high shear granulation is especially critical with the use of viscous liquid binders and with short processing times. A viscous liquid binder was delivered into the powder mass at two flow rates using three methods: pouring, pumping and spraying from a pressure pot. Binder content analyses at the scale of individual granules were conducted to investigate the impact of different delivery conditions on the homogeneity of binder distribution. There was clear evidence of non-uniformity of binder content among individual granules across all delivery conditions, particularly for the fast rates of delivery. Poorer reproducibility values of tablet thickness and disintegration time were observed when binder was poured but this may be overcome by pumping or spraying from the pressure pot. Greater homogeneity of binder distribution occurred with the slow rates of delivery and led to the earlier onset of granule growth and a consequent increase in granule size. Larger granule size and lower proportion of fines were in turn associated with increased granule bulk density and improvement of granule flow. In conclusion, delivery of a viscous binder at a slow rate either by pumping or via a pressure pot was most desirable during granulation. PMID:24269207

  13. Invariant Manifolds and the Stability of Traveling Waves in Scalar Viscous Conservation Laws

    E-print Network

    Wayne, Eugene

    Invariant Manifolds and the Stability of Traveling Waves in Scalar Viscous Conservation Laws solutions of scalar, viscous conservation laws is inves- tigated by decomposing perturbations into three: invariant manifolds, stability of traveling waves, scalar viscous conservation laws, weighted function

  14. Direct laser printing using viscous printer's ink

    SciTech Connect

    Nasibov, A S; Bagramov, V G; Berezhnoi, K V [P.N. Lebedev Physics Institute, Russian Academy of Sciences, Moscow (Russian Federation)

    2006-02-28

    The results of experiments on direct laser printing using viscous printer's ink with the help of a copper vapour laser (CVL)-based device are presented. The highly reflecting CVL cavity mirror was replaced by a spatial mirror modulator (SMM). Viscous printer's ink was used for printing. A pressure pulse produced at the boundary (on which an intensified and diminished image of the SMM was projected) between the ink and a transparency was used for transferring the ink to the plastic card. It was shown that the use of a CVL allowed a maximum printing speed of {approx}80 cm{sup 2} s{sup -1}, a resolution of 625 dpi and up to 15 gradations. The dependence of the emission intensity of the element being projected (pixel) on its diameter is studied. It is shown that an increase in the brightness of this element with decreasing its size is caused by the summation of the laser and amplified radiation. (laser applications and other topics in quantum electronics)

  15. Viscous fluid injection into a confined channel

    NASA Astrophysics Data System (ADS)

    Zheng, Zhong; Rongy, Laurence; Stone, Howard A.

    2015-06-01

    We analyze the injection of a viscous fluid into a two-dimensional horizontal confined channel initially filled with another viscous fluid of different density and viscosity. We study the flow using the lubrication approximation and assume that the mixing between the fluids and their interfacial tension are negligible. When the injection rate is maintained constant, the evolution of the fluid-fluid interface can be described by a nonlinear advection-diffusion equation dependent only on the viscosity ratio between the two fluids. In the early time period, the advection-diffusion equation reduces to a well-known nonlinear diffusion equation, and a self-similar solution is obtained. In the late time period, the advection-diffusion equation is approximated by a nonlinear hyperbolic equation, and a compound wave solution is constructed to describe the time evolution of the fluid-fluid interface. Numerical solutions of the full equation show good agreement with the analytical solutions in both the early and late time periods. Finally, a regime diagram is obtained to summarize the flow behaviours with regard to two dimensionless groups: the viscosity ratio of the two fluids and the dimensionless time; three different dynamical behaviours are identified in the regime diagram: a nonlinear diffusion regime, a hyperbolic regime, and a transition regime. This problem is analogous to the corresponding injection flow problem into a confined porous medium.

  16. Petrofabric test of viscous folding theory

    NASA Astrophysics Data System (ADS)

    Onasch, Charles M.

    1984-06-01

    Compression and extension axes are deduced from quartz deformation lamellae in a quartzite and a graywacke folded into an asymetrical syncline. Deformation lamellae fabrics in the two sandstones are distinctly different. In the graywacke, regardless of bedding orientation or position on the fold, compression axes are normal or nearly normal to the axial planar rough cleavage. Extension axes generally lie in the cleavage plane, parallel to dip. In most quartzite samples, compression axes are parallel or subparallel to bedding, at high angles to the fold axis and extension axes are normal to bedding. Two samples from the very base of the formation indicate compression parallel to the fold axis with extension parallel to bedding, at high angles to the fold axis. One of these two shows both patterns. The lamellae fabric geometry in these two samples suggests the presence of a neutral surface in the quartzite. The lamellae-derived compression and extension axes are in good agreement with the buckling behavior of a viscous layer (quartzite) embedded in a less viscous medium (graywacke and shale below and shale and carbonate above).

  17. Viscous throughflow modeling for multistage compressor design

    SciTech Connect

    Howard, M.A.; Gallimore, S.J. (Rolls-Royce plc, Derby (United Kingdom))

    1993-04-01

    An existing throughflow method for axial compressors, which accounts for the effects of spanwise mixing using a turbulent diffusion model, has been extended to include the viscous shear force on the endwall. The use of a shear force, consistent with a no-slip condition, on the annulus walls in the throughflow calculations allows realistic predictions of the velocity and flow angle profiles near the endwalls. The annulus wall boundary layers are therefore incorporated directly into the throughflow prediction. This eliminates the need for empirical blockage factors or independent annulus boundary layer calculations. The axisymmetric prediction can be further refined by specifying realistic spanwise variations of loss coefficient and deviation to model the three-dimensional endwall effects. The resulting throughflow calculation gives realistic predictions of flow properties across the whole span of a compressor. This is confirmed by comparison with measured data from both low and high-speed multistage machines. The viscous throughflow method has been incorporated into an axial compressor design system. The method predicts the meridional velocity defects in the endwall region and consequently blading can be designed that allows for the increased incidence, and low dynamic head, near the annulus walls.

  18. Remotely operable peristaltic pump

    NASA Technical Reports Server (NTRS)

    Belew, R. R. (inventor)

    1986-01-01

    A peristaltic pump is disclosed which includes a roller assembly on which is mounted a series of pump rollers. As the roller assembly is rotated by a drive gear the pump rollers are driven in reverse rotation by means of a stationary ring gear and pump roller gears. An upper pressure shoe plate and a lower pressure shoe plate are positioned above sets of flexible tubing. The tubing is sandwiched between the pressure shoe plates and the pump rollers. A highly compact pump is provided having twice as many fluid channel lines as is conventional. The peristaltic pump device may be remotely operated by means of a rotary actuator which rotates a driving hub to move the shoe plates by means of eccentrically mounted links. The pressure shoe plates may be moved by the rotary actuator to a loaded position in which the fluid lines are pinched by the pump rollers and fluid is pumped to an unloaded position in which the fluid lines are maintained in an undeformed, uncrimped configuration so that no creases or crimps are set into the fluid lines during periods of prolonged nonuse.

  19. Minimize pump downtime

    SciTech Connect

    Myers, R.D. [ITW Escoweld Systems, Kingwood, TX (United States)

    1995-06-01

    In refineries and petrochemical plants, centrifugal pumps usually lead the list of equipment that is most susceptible to failure. Using guidelines, maintenance mechanics can improve troubleshooting methods when investigating pump bedplates, underlying concrete foundations and grouting problems. Too often, mechanics may improperly diagnose a misalignment--caused by grouting problems--as an unbalance or a bearing-wearing problem when troubleshooting pump failure. Result: bearing, shaft and seal failures occur from a flawed maintenance procedure. Identifying mounting-surface problems can improve pump performance and decrease unit downtime.

  20. Champagne Heat Pump

    NASA Technical Reports Server (NTRS)

    Jones, Jack A.

    2004-01-01

    The term champagne heat pump denotes a developmental heat pump that exploits a cycle of absorption and desorption of carbon dioxide in an alcohol or other organic liquid. Whereas most heat pumps in common use in the United States are energized by mechanical compression, the champagne heat pump is energized by heating. The concept of heat pumps based on other absorption cycles energized by heat has been understood for years, but some of these heat pumps are outlawed in many areas because of the potential hazards posed by leakage of working fluids. For example, in the case of the water/ammonia cycle, there are potential hazards of toxicity and flammability. The organic-liquid/carbon dioxide absorption/desorption cycle of the champagne heat pump is similar to the water/ammonia cycle, but carbon dioxide is nontoxic and environmentally benign, and one can choose an alcohol or other organic liquid that is also relatively nontoxic and environmentally benign. Two candidate nonalcohol organic liquids are isobutyl acetate and amyl acetate. Although alcohols and many other organic liquids are flammable, they present little or no flammability hazard in the champagne heat pump because only the nonflammable carbon dioxide component of the refrigerant mixture is circulated to the evaporator and condenser heat exchangers, which are the only components of the heat pump in direct contact with air in habitable spaces.