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1

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

NASA Astrophysics Data System (ADS)

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.

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

2013-02-01

2

Cavopulmonary assist for the univentricular Fontan circulation: von K?rm?n Viscous Impeller Pump (VIP™)  

PubMed Central

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

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

2010-01-01

3

High Head Unshrouded Impeller Pump Stage Technology  

NASA Technical Reports Server (NTRS)

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.

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

4

CFD analysis of pump consortium impeller  

NASA Technical Reports Server (NTRS)

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 Navier-Stokes flow solver, FDNS, embedded with the extended k-epsilon turbulence model and with appropriate moving interface boundary conditions, is developed to analyze turbulent flows in the turbomachinery devices. The FDNS code was benchmarked with its numerical predictions of the pump consortium inducer, and provides satisfactory results. In the present study, a CFD analysis of the pump consortium impeller will be conducted with the application of the FDNS code. The pump consortium impeller, with partial blades, is the new design concept of the advanced rocket engine.

Cheng, Gary C.; Chen, Y. S.; Williams, R. W.

1992-01-01

5

Rotordynamic characteristics of a shrouded pump impeller  

E-print Network

? Part 1: Current Theory, " Journal of Vibration, Acoustics, Stress, and Reliability in Design, vol. 110, pp. 201 ? 206, 1988. Kirk, R. G. , "Evaluation of Aerodynamic Instability Mechanisms for Centrifu- gal Compressors ? Part 1: Advanced Analysis..., " Journal of Engineering for Poioer, vol. 100, pp. 48-57, 1978. Childs, D. W. , "Fluid ? Structure Interaction Forces at Pump-Impeller? Shroud Surfaces I' or Rotordynamic Calculations, " Journal of Vibration, Acoustics, Stress, and Reliability in Design...

Abou-El-Kheir, Magdy Sobhy

2012-06-07

6

Optimization and Inverse Design of Pump Impeller  

NASA Astrophysics Data System (ADS)

As for pump impellers, the meridional flow channel and blade-to-blade flow channel, which are relatively independent of each other but greatly affect performance, are designed in parallel. And the optimization design is used for the former and the inverse design is used for the latter. To verify this new design method, a mixed-flow impeller was made. Next, we use Tani's inverse design method for the blade loading of inverse design. It is useful enough to change a deceleration rate freely and greatly. And it can integrally express the rear blade loading of various methods by NACA, Zangeneh and Stratford. We controlled the deceleration rate by shape parameter m, and its value became almost same with Tani's recommended value of the laminar airfoil.

Miyauchi, S.; Zhu, B.; Luo, X.; Piao, B.; Matsumoto, H.; Sano, M.; Kassai, N.

2012-11-01

7

Recent progress in developing durable and permanent impeller pump.  

PubMed

Since 1980s, the author's impeller pump has successively achieved the device implantability, blood compatibility and flow pulsatility. In order to realize a performance durability, the author has concentrated in past years on solving the bearing problems of the impeller pump. Recent progress has been obtained in developing durable and permanent impeller blood pumps. At first, a durable impeller pump with rolling bearing and purge system has been developed, in which the wear-less rollers made of super-high-molecular weight polythene make the pump to work for years without mechanical wear; and the purge system enables the bearing to work in saline and heparin, and no thrombus therefore could be formed. Secondly, a durable centrifugal pump with rolling bearing and axially reciprocating impeller has been developed, the axial reciprocation of rotating impeller makes the fresh blood in and out of the bearing and to wash the rollers once a circle; in such way, no thrombus could be formed and no fluid infusion is necessary, which may bring inconvenience and discomfort to the receptors. Finally, a permanent maglev impeller pump has been developed, its rotor is suspended and floating in the blood under the action of permanent magnetic force and nonmagnetic forces, without need for position measurement and feed-back control. In conclusion, an implantable, pulsatile, and blood compatible impeller pump with durability may have more extensive applications than ever before and could replace the donor heart for transplantation in the future. PMID:12099505

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

2002-04-01

8

Viscous pumping inspired by flexible propulsion.  

PubMed

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

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

2014-09-01

9

Origins of hydrodynamic forces on centrifugal pump impellers  

NASA Technical Reports Server (NTRS)

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.

Adkins, Douglas R.; Brennen, Christopher E.

1987-01-01

10

Numerical Simulation of Centrifugal Pump with Double-Suction Impeller  

NASA Astrophysics Data System (ADS)

Numerical simulation is carried out to investigate 3-D complex flow and performance characteristics of double-suction centrifugal pump by using a CFX code. Double-section centrifugal pump consisted of six blades impeller and shroud ring. Rotating speed of closed type impeller is 3000 rpm. Finite-volume method with structured mesh and k-? Shear Stress Transport turbulence model was used to guaranty more accurate prediction of turbulent flow in the pump impeller. Total head, power and overall efficiency were calculated according to the variation of flow rate to obtain performance characteristics of two types of pump. From the results, impeller having smooth curve along the shroud line obtained good performance. Complicated internal flow phenomena through impellers such as flow separation, pressure loss, flow unsteadiness and performance are investigated and discussed.

An, Young-Joon; Shin, Byeong Rog

2010-06-01

11

Analyses of hydrodynamic radial forces on centrifugal pump impellers  

NASA Technical Reports Server (NTRS)

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

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

1988-01-01

12

Distinctive feature of self-oscillations (surging) of impeller pumps  

NASA Astrophysics Data System (ADS)

It has been established experimentally and confirmed analytically that before the stall of a centrifugal impeller pump, self-oscillations (surging) of the pump are set up in the region of ascending cavitation branchings of its monotonically decreasing head characteristic. Beyond this region, the pumping mode of such a pump is absolutely stable. It has been established that changes in the nonstationary operation of a centrifugal impeller pump produced by variation of its wave resistance are diametrically opposite in character in cavitation and cavitation-free modes.

Gotsulenko, V. V.; Gotsulenko, V. N.

2012-01-01

13

Numerical simulation of flow in centrifugal pump with complex impeller  

NASA Astrophysics Data System (ADS)

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.

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

2011-03-01

14

The helical flow pump with a hydrodynamic levitation impeller.  

PubMed

The helical flow pump (HFP) is a novel rotary blood pump invented for developing a total artificial heart (TAH). The HFP with a hydrodynamic levitation impeller, which consists of a multi-vane impeller involving rotor magnets, stator coils at the core position, and double helical-volute pump housing, was developed. Between the stator and impeller, a hydrodynamic bearing is formed. Since the helical volutes are formed at both sides of the impeller, blood flows with a helical flow pattern inside the pump. The developed HFP showed maximum output of 19 l/min against 100 mmHg of pressure head and 11 % maximum efficiency. The profile of the H-Q (pressure head vs. flow) curve was similar to that of the undulation pump. Hydrodynamic levitation of the impeller was possible with higher than 1,000 rpm rotation speed. The normalized index of the hemolysis ratio of the HFP to centrifugal pump (BPX-80) was from 2.61 to 8.07 depending on the design of the bearing. The HFP was implanted in two goats with a left ventricular bypass method. After surgery, hemolysis occurred in both goats. The hemolysis ceased on postoperative days 14 and 9, respectively. In the first experiment, no thrombus was found in the pump after 203 days of pumping. In the second experiment, a white thrombus was found in the pump after 23 days of pumping. While further research and development are necessary, we are expecting to develop an excellent TAH with the HFP. PMID:22926404

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

2012-12-01

15

Cavitating flow investigation inside centrifugal impellers for a condensate pump  

NASA Astrophysics Data System (ADS)

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.

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

2012-11-01

16

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

Microsoft Academic Search

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

M. Zangeneh

1994-01-01

17

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

NASA Astrophysics Data System (ADS)

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.

Zangeneh, M.

1994-04-01

18

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

NASA Astrophysics Data System (ADS)

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.

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

2013-12-01

19

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

NASA Astrophysics Data System (ADS)

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.

Yang, Zhengjun; Wang, Fujun; Zhou, Peijian

2012-09-01

20

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

NASA Technical Reports Server (NTRS)

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.

Harp, J. L., Jr.

1977-01-01

21

A novel permanent maglev impeller TAH: most requirements on blood pumps have been satisfied.  

PubMed

Based on the development of an impeller total artificial heart (TAH) (1987) and a permanent maglev (magnetic levitation) impeller pump (2002), as well as a patented magnetic bearing and magnetic spring (1996), a novel permanent maglev impeller TAH has been developed. The device consists of a rotor and a stator. The rotor is driven radially. Two impellers with different dimensions are fixed at both the ends of the rotor. The levitation of the rotor is achieved by using two permanent magnetic bearings, which have double function: radial bearing and axial spring. As the rotor rotates at a periodic changing speed, two pumps deliver the pulsatile flow synchronously. The volume balance between the two pumps is realized due to self-modulation property of the impeller pumps, without need for detection and control. Because the hemo-dynamic force acting on the left impeller is larger than that on the right impeller, and this force during systole is larger than that during diastole, the rotor reciprocates axially once a cycle. This is beneficial to prevent the thrombosis in the pump. Furthermore, a small flow via the gap between stator and rotor from left pump into right pump comes to a full washout in the motor and the pumps. Therefore, it seems neither mechanical wear nor thrombosis could occur. The previously developed prototype impeller TAH had demonstrated that it could operate in animal experiments indefinitely, if the bearing would not fail to work. Expectantly, this novel permanent magnetic levitation impeller TAH with simplicity, implantability, pulsatility, compatibility and durability has satisfied the most requirements on blood pumps and will have more extensive applications in experiments and clinics. PMID:12873075

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

2003-07-01

22

Numerical study of a centrifugal blood pump with different impeller profiles.  

PubMed

Computational fluid dynamic simulations of the Kyoto-NTN magnetically suspended centrifugal blood pump with 16 forward-bending blades (16FB), 16 straight blades (16SB), and eight backward-bending blades (8BB) impellers were performed in this study. Commercial CFD software package FLUENT were used as the solver. The purpose of this study is to find out how the impeller blade profiles affect the inner flow and the performance of the centrifugal blood pump. The simulations were carried out with the same impeller rotating speed of 2,000 rpm and pump flow rate of 5 L/min to compare the three pump models. It was found that the 16SB impeller can produce higher pressure head than the 16FB and 8BB impellers under the same impeller rotating speed and pump flow rate. The flow particle tracing was carried out to estimate the blood damage level caused by the three different impeller profiles. It was found that the 16FB and 8BB models have caused the highest and lowest blood damage, respectively. The 16SB is recommended among the three pumps because it can generate the highest pressure head and induce mild blood damage index, although it was higher than that of the 8BB model. PMID:20019595

Song, Guoliang; Chua, Leok Poh; Lim, Tau Meng

2010-01-01

23

Viscous pumping inspired by flexible propulsion  

E-print Network

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 appendices 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 fundamental concept, we propose a strategy to produce macroscopic pumping and mixing in creeping flow. We measure 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 flex...

Arco, Roger M; Lauga, Eric; Zenit, Roberto

2014-01-01

24

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

E-print Network

of Fluids Engineering, vol. 113, no. 3, pp. 362-367. Bolleter, U. , Wyss, A. , Welte, I. , Sturchler, R. , 1987, "Measurement of Hydrodynamic Interaction Matrices of Boiler Feed Pump Impellers, " ASME Journal of Vibration, Acoustics, Stress...-59. Childs, D. W. , 1989, "Fluid-Structure Interaction Forces at Pump-Impeller-Shroud Surfaces for Rotordynamic Calculations, "Journal of Vibration, Acoustics, Stress, and Reliability in Design, vol. 111, pp. 216-225. Colnago, Fregeri, and Zanetta, 1989...

Daniel, Arul Sathyasundar

2012-06-07

25

Investigation of the flow in the impeller side clearances of a centrifugal pump with volute casing  

NASA Astrophysics Data System (ADS)

The paper is concerned with the fluid flow in the impeller side clearances of a centrifugal pump with volute casing. The flow conditions in these small axial gaps are of significant importance for a number of effects such as disk friction, leakage losses or hydraulic axial thrust to name but a few. In the investigated single stage pump, the flow pattern in the volute turns out to be asymmetric even at design flow rate. To gain a detailed insight into the flow structure, numerical simulations of the complete pump including the impeller side clearances are accomplished. Additionally, the hydraulic head and the radial pressure distributions in the impeller side clearances are measured and compared with the numerical results. Two configurations of the impeller, either with or without balancing holes, are examined. Moreover, three different operating points, i.e.: design point, part load or overload conditions are considered. In addition, analytical calculations are accomplished to determine the pressure distributions in the impeller side clearances. If accurate boundary conditions are available, the 1D flow models used in this paper can provide reasonable results for the radial static pressure distribution in the impeller side clearances. Furthermore, a counter rotating wake region develops in the rear impeller side clearances in absence of balancing holes which severely affects the inflow and outflow conditions of the cavity in circumferential direction.

Will, Björn-Christian; Benra, Friedrich-Karl; Dohmen, Hans-Josef

2012-06-01

26

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

NASA Astrophysics Data System (ADS)

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.

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

2012-11-01

27

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

E-print Network

of the pressure taps on the front housing. . . . . . Positions of the pressure taps on the back housing. . . . . . Five vaned semi-open impeller Back side of the semi-open impeller. . . . . Side view of the pump housing showing tubes originating from... vaned semi-open impeller of the back swept Figure 13 blade design. Dimensions of the cutaway portion of the 25 semi-open impeller. 26 Figure 14 Velocity triangle at the exit of the impeller. . . . . 35 LIST OF TABLES Page Table 1 Front and back...

Anwer, Sohaib

2012-06-07

28

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

PubMed

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

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

2002-01-01

29

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

PubMed

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

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

2006-03-01

30

Disposable MagLev centrifugal blood pump utilizing a cone-shaped impeller.  

PubMed

To enhance the durability and reduce the blood trauma of a conventional blood pump with a cone-shaped impeller, a magnetically levitated (MagLev) technology has been applied to the BioPump BPX-80 (Medtronic Biomedicus, Inc., Minneapolis, MN, USA), whose impeller is supported by a mechanical bearing. The MagLev BioPump (MagLev BP), which we have developed, has a cone-shaped impeller, the same as that used in the BPX-80. The suspension and driving system, which is comprised of two degrees of freedom, radial-controlled magnetic bearing, and a simply structured magnetic coupling, eliminates any physical contact between the impeller and the housing. To reduce both oscillation of the impeller and current in the coils, the magnetic bearing system utilizes repetitive and zero-power compensators. In this article, we present the design of the MagLev mechanism, measure the levitational accuracy of the impeller and pressure-flow curves (head-quantity [HQ] characteristics), and describe in vitro experiments designed to measure hemolysis. For the flow-induced hemolysis of the initial design to be reduced, the blood damage index was estimated by using computational fluid dynamics (CFD) analysis. Stable rotation of the impeller in a prototype MagLev BP from 0 to 2750 rpm was obtained, yielding a flow rate of 5 L/min against a head pressure in excess of 250 mm Hg. Because the impeller of the prototype MagLev BP is levitated without contact, the normalized index of hemolysis was 10% less than the equivalent value with the BPX-80. The results of the CFD analysis showed that the shape of the outlet and the width of the fluid clearances have a large effect on blood damage. The prototype MagLev BP satisfied the required HQ characteristics (5 L/min, 250 mm Hg) for extracorporeal circulation support with stable levitation of the impeller and showed an acceptable level of hemolysis. The simulation results of the CFD analysis indicated the possibility of further reducing the blood damage of the prototype MagLev BP. PMID:20528854

Hijikata, Wataru; Sobajima, Hideo; Shinshi, Tadahiko; Nagamine, Yasuyuki; Wada, Suguru; Takatani, Setsuo; Shimokohbe, Akira

2010-08-01

31

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

NASA Astrophysics Data System (ADS)

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.

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

2014-03-01

32

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

NASA Astrophysics Data System (ADS)

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.

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

2012-11-01

33

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

NASA Technical Reports Server (NTRS)

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).

Belgacem, Jery

1986-01-01

34

ON THE PARTICLE TRAJECTORIES IN DREDGE PUMP IMPELLERS  

Microsoft Academic Search

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

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

35

J-2X Fuel Pump Impeller Seal Simulations  

NASA Technical Reports Server (NTRS)

The J-2X engine was originally designed for the upper stage of the previously cancelled Crew Launch Vehicle. Although the Crew Launch Vehicle was cancelled the J-2X engine, which is currently undergoing hot-fire testing, may be used on future programs. The J-2X engine is a direct descendent of the J-2 engine which powered the upper stage during the Apollo program. Many changes including a thrust increase from 230K to 294K lbf have been implemented in this engine. The rotor-dynamic stability of the fuel turbopump is highly dependent on the tangential velocity of the fluid as it enters the the front face impeller seal. Rotor-dynamic analysis predicts that a much lower tangential velocity will be required for stability than was needed for previous engines. The geometry at the seal entrance for this engine is very complex and vastly different than previous engines. In order to better determine the fluid dynamics and tangential velocity in this seal several CFD simulations were performed. The results of these simulations show that for this seal geometry a great reduction in the tangential velocity is to be expected. The simulations also provided insight into methods that could be employed to drive the swirl velocity to near zero. Unsteady and time-averaged results of several simulations will be presented.

Schmauch, Preston B.; West, Jeffrey S.

2011-01-01

36

Static stress and modal analysis on the impeller of screw centrifugal pump  

NASA Astrophysics Data System (ADS)

The modeling of the screw centrifugal pump was set up with Pro/E, the meshing of the fluid domain and the impeller were completed with ICEM, CFD and Workbench respectively. The 3-D steady turbulence flow in the pump was simulated by using ANSYS CFX under the design condition to get the pressure distribution on the surface of the blades. The static pressure and modal analysis were set using sequential coupling technique based on the simulation result. The results show that the maximum equivalent stress which is far less than the permissible stress occurs at the blade connected with the hub; the maximum deformation of the impeller occurs at the edge of the blade inlet; the deformation domain increase with the frequency ascended.

Yuan, S. Q.; Li, T.; Yuan, J. P.; Zhou, J. J.

2012-11-01

37

Numerical and Experimental Investigation of Cavitating Characteristics in Centrifugal Pump with Gap Impeller  

NASA Astrophysics Data System (ADS)

This paper is to study the cavitating characteristics in a low specific speed centrifugal pump with gap structure impeller experimentally and numerically. A scalable DES numerical method is proposed and developed by introducing the von Karman scale instead of the local grid scale, which can switch at the RANS and LES region interface smoothly and reasonably. The SDES method can detect and grasp unsteady scale flow structures, which were proved by the flow around a triangular prism and the cavitation flow in a centrifugal pump. Through numerical and experimental research, it's shown that the simulated results match qualitatively with tested cavitation performances and visualization patterns, and we can conclude that the gap structure impeller has a superior feature of cavitation suppression. Its mechanism may be the guiding flow feature of the small vice blade and the pressure auto-balance effect of the gap tunnel.

Zhu, Bing; Chen, Hongxun; Wei, Qun

2014-06-01

38

Effects of the primary passage on the flow through the secondary passage of a shrouded-impeller pump  

E-print Network

EFFECTS OF THE PRIMARY PASSAGE ON THE FLOW THROUGH THE SECONDARY PASSAGE OF A SHROUDED-IMPELLER PUMP A Thesis by NICHOLAS JAMES WYMAN Submitted to the Office of Graduate Studies of Texas AkM University in partial fulfillment... of the requirements for the degree of MASTER OF SCIENCE August 1994 Major subject: Mechanical Engineering EFFECTS OF THE PRIMARY PASSAGE ON THE FLOW THROUGH THE SECONDARY PASSAGE OF A SHROUDED-IMPELLER PUMP A Thesis by NICHOLAS JAMES WYMAN Submitted...

Wyman, Nicholas James

2012-06-07

39

Chaotic mixing of a viscous fluid in a screw impeller mixer  

NASA Astrophysics Data System (ADS)

Several studies on model systems1,2 have established the potential utility of the theory of chaotic systems for the analysis of mixing in laminar flow fields. Here we present an application of the theory to the mixing, under creeping flow conditions, in a screw impeller mixer, which is used in a number of industrial mixing operations. The flow in the system was found to comprise five main components: (i) unidirectional flow in the annulus; (ii) turning slow flow in the lower compartment; (iii) double helical motion in the screw element; (iv) helical motion in the upper part of the draft tube; and (v) turning flow in the upper compartment. Under creeping flow conditions, the flow is independent of the rotational speed of the impeller, thus mixing can be altered only by changing the system geometry. The flow is time independent with respect to a frame of reference fixed on the impeller, and can be considered to be a more complicated version of that in the partitioned pipe mixer.3 Streak lines of the flow are invariant to 2? rotations of the impeller, and illustrate the stretching and folding of material lines by the flow. The development of a streak line starting in the annulus was studied experimentally using a fluorescent tracer dye. Each streak line was found to be segmented into an infinite number of loops each starting at a point on the impeller blade. Each loop in turn was found to be wrapped toroidally around the draft tube. Poincaré sections were obtained by noting the points of intersection of a tracer particle trajectory with a horizontal plane. The coordinate system was fixed either on the tank or on the impeller. Experimentally obtained Poincaré sections were chaotic but showed no structure in either case indicating a well mixed-system to the resolution of the measurements. Studies are currently underway with impellers of varying pitch and length to study their effect on the quality of mixing in terms of Poincaré sections and the extent of stretching of a streak line loop in each rotation of the impeller.

Khakhar, D. V.; Sridhar, G.

1991-05-01

40

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

NASA Astrophysics Data System (ADS)

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.

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

2013-01-01

41

The effect of the impeller-driver magnetic coupling distance on hemolysis in a compact centrifugal pump.  

PubMed

Blood trauma is one of the important performance parameters of centrifugal pumps. To investigate the blood trauma induced by these pumps, in vitro hemolysis tests have become an important procedure and are increasingly used for pump development and comparisons. The Baylor compact eccentric inlet port (CIE) centrifugal blood pump was developed as a long-term centrifugal ventricular assist device (VAD) as well as a cardiopulmonary bypass pump (CPB). The Baylor CIE pump incorporates a seal-less design with a blood stagnation-free structure. This pump can provide flows of 5 L/min against 350 mm Hg of total pressure head at 2,600 revolutions per minute. The pump impeller is magnetically coupled to the driver magnet in a seal-less manner. The latest hemolysis study revealed that hemolysis may be affected by the gap distance between the driver and the impeller magnet. The purpose of this study was to verify the effect of the magnetic coupling distance on the normalized index of hemolysis (NIH) with the CIE model and to obtain an optimal gap distance. The NIH value was clearly decreased by alteration of the magnetic coupling distance from 7.7 to 9.7 mm in CPB and left ventricular assist device (LVAD) conditions. The NIH, when using the pump as an LVAD condition, was reduced to a level of 0.0056 from 0.095 when the magnetic coupling distance was extended. The same results were also obtained when the pumps were used in a CPB condition. The magnetic coupling distance is an important factor for the CIE model in terms of hemolysis. Different coupling forces effect the bearings and impeller stability. These results suggest that an optimal driving condition with a proper magnetic coupling and an optimal force between the impeller and driver is necessary to develop an atraumatic centrifugal pump. PMID:8694696

Nakazawa, T; Makinouchi, K; Takami, Y; Glueck, J; Takatani, S; Nosé, Y

1996-03-01

42

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

PubMed

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

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

2006-01-01

43

Modal behavior of a reduced scale pump-turbine impeller. Part 1: Experiments  

NASA Astrophysics Data System (ADS)

An experimental investigation has been carried out to quantify the effects of surrounding fluid on the modal behavior of a reduced scale pump-turbine impeller. The modal properties of the fluid-structure system have been obtained by Experimental Modal Analysis (EMA) with the impeller suspended in air and inside a water reservoir. The impeller has been excited with an instrumented hammer and the response has been measured by means of miniature accelerometers. The Frequency Response Functions (FRF's) have been obtained from a large number of impacting positions in order to ensure the identification of the main mode shapes. As a result, the main modes of vibration have been well characterized both in air and in water in terms of natural frequency, damping ratio and mode shape. The first mode is the 2 Nodal Diameter (ND), the second one is the 0ND and the following ones are the 3ND coupled with the 1ND. The visual observation of the animated mode shapes and the level of the Modal Assurance Criterion (MAC) have permitted to correlate the homologous modes of vibration of the fluid-structure system in air and in water. From this comparison the added mass effect on the natural frequencies and the fluid effect on the damping ratios have been quantified for the most significant modes. With the surrounding water, the natural frequencies decrease in average by 10%. On the other hand, the damping ratios increase in average by 0.5%. In any case, the damping ratio appears to decrease with the frequency value of the mode.

Escaler, X.; Hütter, J. K.; Egusquiza, E.; Farhat, M.; Avellan, F.

2010-08-01

44

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)

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.

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

2013-12-01

45

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

NASA Astrophysics Data System (ADS)

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.

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

2012-11-01

46

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

NASA Astrophysics Data System (ADS)

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.

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

2012-04-01

47

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

NASA Astrophysics Data System (ADS)

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

Pei, Ji; Yuan, Shouqi; Yuan, Jianping

2014-03-01

48

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

E-print Network

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

Kenis, Paul J. A.

49

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

NASA Astrophysics Data System (ADS)

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.

Cao, Nhai The

1993-12-01

50

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

NASA Astrophysics Data System (ADS)

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.

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

2013-12-01

51

Unshrouded Centrifugal Turbopump Impeller  

NASA Technical Reports Server (NTRS)

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.

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

1999-01-01

52

Impeller shroud to casing leakage flow simulations in the Space Shuttle Main Engine high pressure fuel pump  

NASA Technical Reports Server (NTRS)

Quasi-three-dimensional Navier-Stokes calculations were carried out for the Space Shuttle Main Engine high-pressure fuel pump to simulate the impeller shroud to casing leakage flow. This flow geometry was modeled as an axisymmetric cavity flow with a stationary surface representing the casing, and a rotating surface denoting the impeller. A 63 x 81-node mesh provided sufficient resolution in the regions of greatest flow variations and reduced the effects of numerical diffusion. The turbulence field was closed with the high Reynolds number form of the k-epsilon model supplemented with wall functions in the vicinity of the walls. Finally, a parametric study quantified the effects of through mass flow changes on this leakage flow.

Sindir, Munir M.

1987-01-01

53

Experimental measurements of hydrodynamic stiffness matrices for a centrifugal pump impeller  

NASA Technical Reports Server (NTRS)

The objective of the Rotor Force Test Facility at the California Institute of Technology is to artificially orbit the center of rotation of an impeller enclosed within a volute over a range of frequencies from zero to synchronous and to measure the resulting forces on the impeller. Preliminary data from the first stage experiments in which the shaft is orbited at low frequency is reported. Steady volute forces along with stiffness matrices due to the change in position of the rotor center are measured. Static pressure taps around the volute are used to obtain volute pressure distributions for various fixed positions of the impeller center and for various flow rates. Static pressure forces are calculated from these pressure distributions allowing a more complete analysis of the components of the impeller forces. Comparison is made with various existing theoretical and experimental results.

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

1982-01-01

54

Parametric study of blade tip clearance, flow rate, and impeller speed on blood damage in rotary blood pump.  

PubMed

Phenomenological studies on mechanical hemolysis in rotary blood pumps have provided empirical relationships that predict hemoglobin release as an exponential function of shear rate and time. However, these relations are not universally valid in all flow circumstances, particularly in small gap clearances. The experiments in this study were conducted at multiple operating points based on flow rate, impeller speed, and tip gap clearance. Fresh bovine red blood cells were resuspended in phosphate-buffered saline at about 30% hematocrit, and circulated for 30 min in a centrifugal blood pump with a variable tip gap, designed specifically for these studies. Blood damage indices were found to increase with increased impeller speed or decreased flow rate. The hemolysis index for 50-microm tip gap was found to be less than 200-microm gap, despite increased shear rate. This is explained by a cell screening effect that prevents cells from entering the smaller gap. It is suggested that these parameters should be reflected in the hemolysis model not only for the design, but for the practical use of rotary blood pumps, and that further investigation is needed to explore other possible factors contributing to hemolysis. PMID:19473143

Kim, Nahn Ju; Diao, Chenguang; Ahn, Kyung Hyun; Lee, Seung Jong; Kameneva, Marina V; Antaki, James F

2009-06-01

55

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

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...

Park, Sang

2010-01-16

56

Effect of a bearing gap on hemolytic property in a hydrodynamically levitated centrifugal blood pump with a semi-open impeller.  

PubMed

We have developed a hydrodynamically levitated centrifugal blood pump with a semi-open impeller for long-term circulatory assist. The pump uses hydrodynamic bearings to enhance durability and reliability without additional displacement-sensors or control circuits. However, a narrow bearing gap of the pump has a potential for hemolysis. The purpose of this study is to develop the hydrodynamically levitated centrifugal blood pump with a semi-open impeller, and to evaluate the effect of a bearing gap on hemolytic property. The impeller levitates using a spiral-groove type thrust bearing, and a herringbone-groove type radial bearing. The pump design was improved by adopting a step type thrust bearing and optimizing the pull-up magnetic force. The pump performance was evaluated by a levitation performance test, a hemolysis test and an animal experiment. In these tests, the bearing gap increased from 1 to 63 ?m. In addition, the normalized index of hemolysis (NIH) improved from 0.415 to 0.005 g/100 l, corresponding to the expansion of the bearing gap. In the animal experiment for 24 h, the plasma-free hemoglobin remained within normal ranges (<4.0 mg/dl). We confirmed that the hemolytic property of the pump was improved to the acceptable level by expanding the bearing gap greater than 60 ?m. PMID:23442235

Kosaka, Ryo; Nishida, Masahiro; Maruyama, Osamu; Yambe, Tomoyuki; Imachi, Kou; Yamane, Takashi

2013-01-01

57

[Hemolysis test of the five kinds of impeller blood pumps in vitro].  

PubMed

Hemolysis caused by blood pumps is a very important characteristic. In vitro hemolysis test circuits were constructed to operate the model I centrifugal pump, the model II axial flow pump, the magnetic coupling pump and the model I & II spiral mixed pump. The output of all pumps was set at flow 5 L/min, an average pressure of 100 mmHg. Experiments were conducted for 4 hours at room temperature(25 degrees C) with 500 ml fresh anticoagulant sheep blood. Blood samples were taken for plasma free-hemoglobin measurement, and the change in temperature at the pump outlet port was measured during the experiment. Calculate the normalized index of hemolysis (NIH). The results showed that there was no relationship either between the pump rotational speed and the NIH in five types of blood pumps, or between change in temperature at the pump outlet port and NIH. The dynamic fluid field caused by pump design and structure could be the main cause of blood damage. PMID:12557528

Li, Bingyi; Lin, Changyan; Jiang, Yiling; Wang, Jing; Chen, Lizheng

2002-09-01

58

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

SciTech Connect

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)

Hamrick, J.T.

1980-04-01

59

A finite-element-based perturbation model for the rotordynamic analysis of shrouded pump impellers: Part 2: User's guide  

NASA Technical Reports Server (NTRS)

This report describes the computational steps involved in executing a finite-element-based perturbation model for computing the rotor dynamic coefficients of a shrouded pump impeller or a simple seal. These arise from the fluid/rotor interaction in the clearance gap. In addition to the sample cases, the computational procedure also applies to a separate category of problems referred to as the 'seal-like' category. The problem, in this case, concerns a shrouded impeller, with the exception that the secondary, or leakage, passage is totally isolated from the primary-flow passage. The difference between this and the pump problem is that the former is analytically of the simple 'seal-like' configuration, with two (inlet and exit) flow-permeable stations, while the latter constitutes a double-entry / double-discharge flow problem. In all cases, the problem is that of a rotor clearance gap. The problem here is that of a rotor excitation in the form of a cylindrical whirl around the housing centerline for a smooth annular seal. In its centered operation mode, the rotor is assumed to give rise to an axisymmetric flow field in the clearance gap. As a result, problems involving longitudinal or helical grooves, in the rotor or housing surfaces, go beyond the code capabilities. Discarding, for the moment, the pre- and post-processing phases, the bulk of the computational procedure consists of two main steps. The first is aimed at producing the axisymmetric 'zeroth-order' flow solution in the given flow domain. Detailed description of this problem, including the flow-governing equations, turbulence closure, boundary conditions, and the finite-element formulation, was covered by Baskharone and Hensel. The second main step is where the perturbation model is implemented, with the input being the centered-rotor 'zeroth-order' flow solution and a prescribed whirl frequency ratio (whirl frequency divided by the impeller speed). The computational domain, in the latter case, is treated as three dimensional, with the number of computational planes in the circumferential direction being specified a priori. The reader is reminded that the deformations in the finite elements are all infinitesimally small because the rotor eccentricity itself is a virtual displacement. This explains why we have generically termed the perturbation model the 'virtually' deformable finite-element category. The primary outcome of implementing the perturbation model is the tangential and radial components, F(sub theta)(sup *) and F(sub r)(sup *) of the fluid-exerted force on the rotor surface due to the whirling motion. Repetitive execution of the perturbation model subprogram over a sufficient range of whirl frequency ratios, and subsequent interpolation of these fluid forces, using the least-square method, finally enable the user to compute the impeller rotor dynamic coefficients of the fluid/rotor interaction. These are the direct and cross-coupled stiffness, damping, and inertia effects of the fluid/rotor interaction.

Baskharone, Erian A.

1993-01-01

60

Impeller shroud  

Microsoft Academic Search

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

1987-01-01

61

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

E-print Network

the importance of the underlying fluid mechanics. The complex interactions which occur between the fluid and the rotating parts of the pump are not clearly understood. Consequently, modern designs cannot fully compensate for the adverse effects... instabilities which damage the pump. The other limiting phenomena is cavitation. Here, localized increases The ASME Journal of Fluids Engineering was used for style and format. in velocity, which result from curvature effects or from a reduction of the cross...

Moran, Michael Kevin

2012-06-07

62

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

Microsoft Academic Search

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

Erian A. Baskharone

1993-01-01

63

Space Shuttle Main Engine structural analysis and data reduction/evaluation. Volume 7: High pressure fuel turbo-pump third stage impeller analysis  

NASA Technical Reports Server (NTRS)

This volume summarizes the analysis used to assess the structural life of the Space Shuttle Main Engine (SSME) High Pressure Fuel Turbo-Pump (HPFTP) Third Stage Impeller. This analysis was performed in three phases, all using the DIAL finite element code. The first phase was a static stress analysis to determine the mean (non-varying) stress and static margin of safety for the part. The loads involved were steady state pressure and centrifugal force due to spinning. The second phase of the analysis was a modal survey to determine the vibrational modes and natural frequencies of the impeller. The third phase was a dynamic response analysis to determine the alternating component of the stress due to time varying pressure impulses at the outlet (diffuser) side of the impeller. The results of the three phases of the analysis show that the Third Stage Impeller operates very near the upper limits of its capability at full power level (FPL) loading. The static loading alone creates stresses in some areas of the shroud which exceed the yield point of the material. Additional cyclic loading due to the dynamic force could lead to a significant reduction in the life of this part. The cyclic stresses determined in the dynamic response phase of this study are based on an assumption regarding the magnitude of the forcing function.

Pool, Kirby V.

1989-01-01

64

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

E-print Network

. Figure 6. Figure 7. Figure 8. Figure 9. Figure 10. Figure 11. Radial force coefficient curves from Childs [19]. Tangential force coefficient curves from Childs [19] 12 12 Dependency of K" on whirl frequency ratio. Dependency of k' on whirl..., these are only a few of the many variables affecting pump dynamics. More recent examples of static force measurements are given by Kanki et al. [5], Schwarz and Wesche [6] and Uchida [7]. These researchers introduce additional variables including volute shape...

Williams, James Philip

2012-06-07

65

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)

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.

Baskharone, Erian A.

1993-09-01

66

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

E-print Network

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. The compressible model is compared with the incompressible model and the acoustic model. A solution due to impeller discharge pressure disturbances model...

Cao, Nhai The

2012-06-07

67

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

NASA Technical Reports Server (NTRS)

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.

Russell, John M.

2002-01-01

68

Influence of impeller and diffuser geometries on the lateral fluid forces of whirling centrifugal impeller  

NASA Technical Reports Server (NTRS)

Lateral fluid forces on two-dimensional centrifugal impellers, which whirl on a circular orbit in a vaneless diffuser, were reported. Experiments were further conducted for the cases in which a three-dimensional centrifugal impeller, a model of the boiler feed pump, whirls in vaneless and vaned diffusers. The influence of the clearance configuration between the casing and front shroud of the impeller was also investigated. The result indicated that the fluid dynamic interaction between the impeller and the guide vanes induces quite strong fluctuating fluid forces to the impeller, but nevertheless its influence on radial and tangential force components averaged over a whirling orbit is relatively small.

Ohashi, Hideo; Sakurai, Akira; Nishihama, Jiro

1989-01-01

69

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

NASA Astrophysics Data System (ADS)

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).

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

1992-07-01

70

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

NASA Technical Reports Server (NTRS)

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).

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

1992-01-01

71

Latest update of tests and improvements to US Coast Guard viscous oil pumping system.  

PubMed

Over the past nine years, the US Coast Guard has incorporated the prevention through people (PTP) philosophy as a "human factors" approach to learn how maritime operations can be regulated safer and be more efficient by evaluating training, management policies, operational procedures, and establishing partnerships with the maritime industry. One of the key elements of applying a PTP approach is identifying and incorporating lessons learned from major marine casualties and pollution incidents. Since 1997, the US Coast Guard National Strike Force has responded to three major oil spills involving foreign freight vessels grounding, which included the removal of highly viscous oil using various lightering equipment and systems. An informal workgroup consisting of the US Coast Guard, US Navy Supervisor of Salvage (NAVSUPSALV), and various representatives from oil pollution clean-up companies met at the following facilities: the Chevron Asphalt Facility in Edmonds, WA (September 1999), the Oil and Hazardous Materials Simulated Environmental Test Tank (OHMSETT) testing facility in Leonardo, New Jersey (November 1999 and March 2000), the Alaska Clean Seas (ACS) warehouse annex in Prudhoe Bay, AK (October 2000), and Cenac Towing Company facility in Houma, LA (May 2002). The group shared ideas and techniques, and tested different pumps and hose lengths with viscous oil. It was during the early tests that the first quantitative results showed just how efficient lubricated transport of heavy oil product could be, and broadened the knowledge of such methods to the entire industry. Although this technology had existed for many years in the oil production and handling industry, its use had never been investigated in a laboratory setting with regard to salvage response lightering systems. PMID:12899890

Drieu, Michael D; Nourse, Peter C; MacKay, Ronald; Cooper, David A; Hvidbak, Flemming

2003-01-01

72

Dissipation in peristaltic pumping of a compressible viscous fluid through a planar duct or a circular tube.  

PubMed

When a compressible viscous fluid is pumped through a linear channel by means of a running surface wave on the wall, energy is dissipated in the fluid. The rate of dissipation can be evaluated effectively from the work performed on the fluid by the wavy wall. Explicit expressions are derived for the rate of dissipation for a planar duct and a circular tube, valid to second order in the amplitude of the surface wave. In both cases the rate of dissipation shows a resonance as a function of frequency when the phase velocity of the surface wave equals the sound velocity of the fluid. PMID:21599298

Felderhof, B U

2011-04-01

73

Viscous flow prediction within a centrifugal impeller  

E-print Network

ratio 5. 3:1, hub streamline 25 12 Variation of relative velocity on the blade-to-blade plane, Pressure ratio 5. 3:1, mid streamline 26 13 Variation of relative velocity on the blade-to-blade plane, Pressure ratio 5. 3:1, shroud streamline 27... on the blade-to-blade plane, Pressure ratio 1. 2:1, mid streamline 31 17 Variation of relative velocity on the blade-to-blade plane, Pressure ratio 1. 2:1, shroud streamline 32 18 Relationship between cylindrical coordinate system and streamline coordinate...

Wohlschlegel, David Hale

2012-06-07

74

Full 3-D viscous optimization design of a reversible pump turbine runner  

NASA Astrophysics Data System (ADS)

The bi-directional operation of reversible pump turbines presents a great challenge in terms of runner design. In the present paper, an optimal design system for the pump turbine runner is presented by coupling three-dimensional (3-D) inverse design with the Computational Fluid Dynamics (CFD), Design of Experiment (DoE), Response Surface Methodology (RSM) and Multi Objective Genetic Algorithm (MOGA). A pump-turbine runner was designed using the system, with selecting blade loading distributions and blade lean as the input parameters, and the runner efficiency for both pump and turbine mode as optimization objectives. The CFD results show that a high efficiency runner can be designed using the present system.

Wang, X. H.; Zhu, B. S.; Cao, S. L.; Tan, L.

2013-12-01

75

Advanced impeller geometry boosts liquid agitation  

SciTech Connect

A traditional agitator impeller often functions as a rather inefficient pump because of the way it produces fluid motion and pressure head. However, one can improve the amount of flow or shear generated by an impeller at constant power consumption and torque by changing its design. For example, a high-efficiency, axial-flow impeller produces more fluid motion per unit of power at constant torque than an otherwise similar pitched-blade turbine. The more-vigorous fluid motion cuts blend time and enhances heat-transfer in various flow-controlled mixing operations, such as blending of miscible fluids. For most applications, a higher degree of agitation intensity can be achieved on the same machine by substituting a high-efficiency impeller for a conventional pitched-blade unit. The high-efficiency impeller features a larger geometric pitch angle (30--60 deg) at the hub than at the tip (10--30 deg). Results from recently conducted controlled experiments indicate the beneficial effects of the high-efficiency impeller on blend time and heat-transfer coefficients in liquid-liquid mixing as well as solids suspension. This articles focuses on liquid agitation, with discussions of solids suspension set aside for a forthcoming piece in this series of articles on mixing.

Fasano, J.B.; Bakker, A.; Penney, W.R. (Univ. of Arkansas, Fayetteville, AR (United States))

1994-08-01

76

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

Microsoft Academic Search

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

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

2004-01-01

77

Viscous to inertial pumping transitions in a robotic gill plate array  

NASA Astrophysics Data System (ADS)

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.

Larson, Mary; Kiger, Ken

2010-11-01

78

Artificial Heart Rejects High Tech? Lessens Learnt from Non-pulsatile VAD with Straight Impeller Vanes  

PubMed Central

Despite the progresses in developing pulsatile impeller pump and impeller total heart, as well as in applying streamlined impeller vanes, the best results in application of artificial heart pumps have been achieved by nonpulsatile univentricular assist pump with straight impeller vanes until now. It seems all efforts and successes have been done in vain because artificial heart rejects Hi-Tech! This paper recalls some important achievements in R&D of artificial heart in past 25 years and shares author’s experiences with the readers. PMID:19662125

Qian, Kun-xi

2007-01-01

79

Impeller flow field measurement and analysis  

NASA Technical Reports Server (NTRS)

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.

Fagan, J. R.; Fleeter, S.

1991-01-01

80

Impeller flow field measurement and analysis  

NASA Astrophysics Data System (ADS)

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.

Fagan, J. R.; Fleeter, S.

1991-10-01

81

Aerodynamic Synthesis of a Centrifugal Impeller Using CFD and Measurements  

NASA Technical Reports Server (NTRS)

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.

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

1997-01-01

82

Development and Validation of High Performance Unshrouded Centrifugal Impeller  

NASA Technical Reports Server (NTRS)

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

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

2001-01-01

83

Transient internal characteristic study of a centrifugal pump during startup process  

NASA Astrophysics Data System (ADS)

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.

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

2012-11-01

84

The viscous fluid pump.  

PubMed

We describe a device useful for injection of viscoelastic material into the vitreous cavity for internal tamponade. The instrument has proven to be reliable and "user friendly" in a clinical setting. PMID:2250879

Davidorf, F; Chambers, R B; Reimels, H

1990-09-01

85

Axial Pump  

NASA Technical Reports Server (NTRS)

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.

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

86

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

NASA Astrophysics Data System (ADS)

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.

Shigemaru, Daichi; Tsukamoto, Hiroshi

2010-06-01

87

Swirling impeller flow  

NASA Astrophysics Data System (ADS)

The results of extensive laser measurements carried out in the blade passages of a newly designed backswept impeller are presented and discussed. Noticeable distortions of the through flow patterns and a distinct swirling flow character were found inside the rotor. The measurement results and a simple theoretical approach suggest that the distorted through flow patterns and the secondary flows are caused by a vortex flow.

Krain, H.

1987-05-01

88

CFD analyses for advanced pump design  

NASA Astrophysics Data System (ADS)

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.

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

1994-04-01

89

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)

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.

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

1953-01-01

90

Apparatus for pumping liquids at or below the boiling point  

DOEpatents

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.

Bingham, Dennis N. (Idaho Falls, ID)

2002-01-01

91

An improved theory for regenerative pump performance  

E-print Network

, impeller angles, CFD 1 INTRODUCTION Regenerative flow pumps and compressors have found many applications for the pump performance. The model can handle one inlet angle and two exit angles for the impeller blades and it can be used for the design of twisted blades that would increase the pump head and efficiency. A new

Kim, Yong Jung

92

Electrodiffusional flow diagnostics in a centrifugal pump  

Microsoft Academic Search

This paper presents electrodiffusional measurements of the wall shear rate at the impeller surface of a radial centrifugal pump. Twelve probes of different radii and at different positions along one blade were used in a pump with an open six bladed impeller. By means of throttling and speed control the operating point of the pump was adjusted and the influence

M. Lutz; V. Denk; K. Wichterle; V. Sobolik

1998-01-01

93

Impeller flow field characterization with a laser two-focus velocimeter  

NASA Astrophysics Data System (ADS)

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.

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

1993-07-01

94

Impeller flow field characterization with a laser two-focus velocimeter  

NASA Technical Reports Server (NTRS)

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. The 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.

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

1993-01-01

95

Measuring axial pump thrust  

DOEpatents

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.

Suchoza, B.P.; Becse, I.

1988-11-08

96

Measuring axial pump thrust  

DOEpatents

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.

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

1988-01-01

97

Rotary blood pump  

NASA Technical Reports Server (NTRS)

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.

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

98

Design of centrifugal impeller blades  

NASA Technical Reports Server (NTRS)

This paper restricts itself to radial impellers with cylindrical blades since, as Prasil has shown, the flow about an arbitrarily curved surface of revolution may be reduced to this normal form we have chosen by a relatively simple conformal transformation. This method starts from the simple hypotheses of the older centrifugal impeller theory by first assuming an impeller with an infinite number of blades. How the flow is then modified is then investigated. For the computation of flow for a finite number of blades, the approximation method as developed by Munk, Prandtl and Birnbaum, or Glauert is found suitable. The essential idea of this method is to replace the wing by a vortex sheet and compute the flow as the field of these vortices. The shape of the blades is then obtained from the condition that the flow must be along the surface of the blade.

Betz, A; Flugge-Lotz, I

1939-01-01

99

Eckardt's impeller: A ghost from ages past  

Microsoft Academic Search

Equations are presented which give an approximate representation of blade camber line profiles and of hub and shroud profiles of Eckardt's impeller. Also presented are equations describing the corresponding profiles of a centrifugal impeller used in the De Havilland Ghost engine. It is found that both impellers were designed with elliptical blade camber line profiles and circular arc hub and

J. Moore

1976-01-01

100

Oil filaments produced by an impeller in a water stirred tank  

NASA Astrophysics Data System (ADS)

Oil dispersions in aqueous media produced in stirred tanks are part of many industrial processes. The oil drops size and dispersion stability are determined by the impeller geometry, stirring velocity and the physicochemical properties of the mixture. A critical parameter is the total interfacial area which is increased as the drop size is decreased. The mechanism that disperses the oil and generates the drops has not been completely explained. In the present work, castor oil (1% v/v, viscosity 500mPa) and water are stirred with a Scaba impeller in a flat bottom cylindrical tank. The process was recorded with high-speed video and the Reynolds number was fixed to 24,000. Before the stirring, the oil is added at the air water interface. At the beginning of the stirring, the oil is suctioned at the impeller shaft and incorporated into the flow ejected by the impeller. In this region, the flow is turbulent and exhibits velocity gradients that elongate the oil phase. Viscous thin filaments are generated and expelled from the impeller. Thereafter, the filaments are elongated and break to form drops. This process is repeated in all the oil phase and drops are incorporated into the dispersion. Two main zones can be identified in the tank: the impeller discharge characterized by high turbulence and the rest of the flow where low velocity gradients appear. In this region surface forces dominate the inertial ones, and drops became spheroidal.

Sanjuan-Galindo, Rene; Soto, Enrique; Ascanio, Gabriel; Zenit, Roberto

2010-11-01

101

Rotary Blood Pump  

NASA Technical Reports Server (NTRS)

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.

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

102

[Improved design of permanent maglev impeller assist heart].  

PubMed

Magnetic bearing has no mechanical contact between the rotor and stator. And a rotary pump with magnetic bearing has therefore no mechanical wear and thrombosis due to bearing. The available magnetic bearings, however, are devised with electric magnets, need complicated control and remarkable energy consumption. Resultantly, it is difficult to apply an electric magnetic bearing to rotary pump without disturbing its simplicity, implantability and reliability. The authors have developed a levitated impeller pump merely with permanent magnets. The rotor is supported by permanent magnetic forces radially. On one side of the rotor, the impeller is fixed; and on the other side of the rotor, the driven magnets are mounted. Opposite to this driven magnets, a driving motor coil with iron corn magnets is fastened to the motor axis. Thereafter, the motor drives the rotor via a rotating magnetic field. By laboratory tests with saline, if the rotor stands still or rotates under 4,000 rpm, the rotor has one-point contact axially with the driving motor coil. The contacting point is located in the center of the rotor. As the rotating speed increases gradually to more than 4,000 rpm, the rotor will detache from the stator axially. Then the rotor will be fully levitated. Since the axial levitation is produced by hydraulic force and the driven magnets have a gyro-effect, the rotor rotates very steadly during levitation. As a left ventricular assist device, the pump works in a rotating speed range of 5,000-8,000 rpm, the levitation of the impeller hence is ensured by practical use of the pump. PMID:12561356

Qian, Kunxi; Zeng, Pei; Ru, Weimin; Yuan, Haiyu

2002-12-01

103

Flow in a centrifugal fan impeller at off-design conditions  

NASA Astrophysics Data System (ADS)

A fully three-dimensional finite element analysis of inviscid, incompressible blade channel flow is the basis of the present study of both predicted and measured surface velocity and pressure distributions in the internal flow channels of a centrifugal fan impeller, for volume flow rates of 80-125 percent the design flow rate. The experimental results made extensive use of blade and sidewall surface pressure taps installed in a scale model of an airfoil-bladed centrifugal fan impeller. The results obtained illustrate the ability of both flow analyses to predict the dominant features of the impeller flow field, including peak blade surface velocities and adverse gradients at flows far from the design point. Insight is also gained into the limiting channel diffusion values for typical centrifugal cascade performance, together with the influence of viscous effects, as seen in deviations from ideal flow predictions.

Wright, T.; Tzou, K. T. S.; Madhavan, S.

1984-06-01

104

Estimation of losses in semi-open centrifugal impellers  

NASA Astrophysics Data System (ADS)

In centrifugal impellers of the semiopen type (impellers without front shroud), the clearance between the vanes and the stationary casing, known as tip clearance, has a deciding role on the overall performance of the machine. Tip clearance flows are an important source of turbomachinery energy loss. The deterioration of compressor and pump performance due to tip clearance, are often found in the literature, expressed in different ways with widely varying coefficients, depending on machine and fluid type. Practice shows these relationships to be unreliable, since most of them are based on simplified flow models where the impact of the simplifications are also unknown. Some of these relationships and the merits and setbacks of each are studied.

Engeda, A.; Rauntenberg, M.

105

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

E-print Network

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 ...

Tarr, David Landon

2008-01-01

106

Realization of a permanent implantable pulsatile impeller heart with magnetically suspended motor.  

PubMed

A permanent impeller heart that could work for years was once an idea. However, now this idea is turning into reality through the use of the magnetically suspended motor. Recently, with our implantable pulsatile impeller pump, 3 left ventricular assisted calves survived for about 2 months (62, 54, and 46 days, respectively). The termination of the experiments was related to wear of the mechanical bearing, which resulted in vibration of the rotor and pump failure. All the experimental animals were in good condition prior to pump failure. It seemed as if the experiments could have lasted indefinitely if the bearing had not failed. All the hematological and biochemical data of the calves remained in normal or acceptable ranges; neither blood damage nor organ dysfunction of any animal was detected. During autopsy, no severe thrombus formation was found in the pump or vessels although a low dose of heparin (0.5-0.8 g/h) was given to increase the activated coagulation time (ACT) to 1.5-2.0 times its normal value. To solve the problem of bearing wear, a magnetically suspended motor was investigated and applied to the impeller pump. On the opposite sides of a disc connected to the rotor, 2 permanent magnet rings were embedded, one for driving and the other for axial suspension. Because both the driving and suspending coils with iron cores attract the disc, no radial bearing was needed. This newly devised impeller heart promises to have long-term and permanent applications. PMID:9212937

Qian, K X; Zheng, M

1997-07-01

107

Single-disk and double-disk viscous micropumps  

Microsoft Academic Search

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

Danny Blanchard; Phil Ligrani; Bruce Gale

2005-01-01

108

Fluid dynamic characteristics of monopivot magnetic suspension blood pumps.  

PubMed

A monopivot magnetic suspension blood pump is a centrifugal pump under development with a magnetic suspension and a ceramic pivot to support the impeller with minimum contact. The pump size has been reduced by implementing a direct impeller drive mechanism in place of a magnetic coupling and motor. Flow visualization studies revealed that high shear, which seems to be closely related to hemolysis, concentrates in boundary layers near the walls. This implies that fluid dynamic shear can be reduced not by widening the gap, but by reducing the impeller velocity. Therefore, compared with the results of the previous semi-open curved vane impeller model, impeller velocity was reduced by 30% with a closed impeller having radial straight vanes, and smaller impeller/housing gaps. The volute shape around the impeller tip was also changed such that the outflow from the impeller enters along the center plane of the volute. To examine the effect of the improvements, hemolysis testing was conducted and found that the newly developed closed impeller model generated a lower level of hemolysis than the previous semi-open impeller model. PMID:9360122

Yamane, T; Nishida, M; Asztalos, B; Tsutsui, T; Jikuya, T

1997-01-01

109

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

PubMed Central

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

2013-01-01

110

An intraventricular axial flow blood pump integrated with a bearing purge system.  

PubMed

The future development of implantable axial flow blood pumps must address two major issues: mechanically induced hemolysis and shaft seal reliability. The recent revisions to our miniature intraventricular axial flow left ventricular assist device (LVAD) were aimed particularly at addressing these concerns. To improve hemocompatibility, a new impeller has been designed according to the following criteria: 1) gradual pressure rise along the blade chord; 2) minimized local fluid acceleration to prevent cavitation; 3) minimum surface roughness; and 4) radius edges. Subsequent in vitro hemolysis tests conducted with bovine and ovine blood have demonstrated very low hemolysis (normalized index of hemolysis = 0.0051 +/- 0.0047 g/100 L) with this new impeller design. To address the need for a reliable seal, we have developed a purged seal system consisting of a miniature lip seal and ceramic pressure groove journal bearing that also acts as a purge pump. Several spiral grooves formed on the bearing surface provide viscous pumping of the purge fluid, generating more than 3,000 mmHg at 10,000 rpm. This purge flow flushes the lip seal and prevents blood backflow into the bearing. We have found this purge pump to offer several advantages because it is simple, compact, durable, does not require separate actuation, and offers a wide range of flow, depending upon the groove design. In vivo animal tests demonstrated the potential of the purged seal system. PMID:8573818

Yamazaki, K; Kormos, R; Mori, T; Umezu, M; Kameneva, M; Antaki, J; Outa, E; Litwak, P; Kerrigan, J; Tomczak, J

1995-01-01

111

AN OPTIMIZATION TECHNIQUE FOR RADIAL COMPRESSOR IMPELLERS  

Microsoft Academic Search

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

Michael Casey; Frank Gersbach; Chris Robinson

2008-01-01

112

The Development of a Centrifugal Compressor Impeller  

Microsoft Academic Search

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

C. Xu; R. S. Amano

2009-01-01

113

Viscous Fluids  

NSDL National Science Digital Library

Students are introduced to the similarities and differences in the behaviors of elastic solids and viscous fluids. Several types of fluid behaviors are describedâBingham plastic, Newtonian, shear thinning and shear thickeningâalong with their respective shear stress vs. rate of shearing strain diagrams. In addition, fluid material properties such as viscosity are introduced, along with the methods that engineers use to determine those physical properties.

Integrated Teaching And Learning Program

114

Magnetically suspended miniature fluid pump and method of designing the same  

NASA Technical Reports Server (NTRS)

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.

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

2000-01-01

115

Flowfield analysis of a backswept centrifugal impeller  

NASA Astrophysics Data System (ADS)

A time-dependent, three-dimensional Navier-Stokes algorithm has been applied to analyze the complex flowfield within a backswept centrifugal impeller. Issues studied include parametric analyses into the effect of secondary flow structures, due to tip leakage flow, on the development of the flowfield within the impeller passage, and off-design, or part load, analyses at conditions below (60 and 80 percent) the reference volumetric flow rate. Excellent agreement with available experimental data verifies the numerical rig as a viable technique, and suggests its ability to assist in the design process of impeller geometries.

Mounts, Jon S.; Dorney, Daniel J.; Brasz, Joost J.

1991-06-01

116

Use of partially shrouded impeller in a small centrifugal compressor  

Microsoft Academic Search

Numerical analysis is conducted for the 3-dimensional impeller and vaneless diffuser of a small centrifugal compressor. The\\u000a influence of impeller tip clearance on the flow field of the impeller is investigated. Detailed investigation on the leaking\\u000a flow across the tip clearance of the impeller shows that the leaking flow rate is higher near the exit of the impeller than\\u000a that

Jin Tang; Teemu Turunen-Saaresti; Jaakko Larjola

2008-01-01

117

Effect of temperature on resonance of impellers  

E-print Network

was selected to analyze acoustic signal generated in the test section due to vibrations of test impeller . 24 TABLE III SPECIFICATIONS FOR THE MINIATURE ACCELEROMETER TYPE 4344 Yoltage Sensitivity: Charge Sensitivity: Frequency Range: 10% Dynamic Range... was selected to analyze acoustic signal generated in the test section due to vibrations of test impeller . 24 TABLE III SPECIFICATIONS FOR THE MINIATURE ACCELEROMETER TYPE 4344 Yoltage Sensitivity: Charge Sensitivity: Frequency Range: 10% Dynamic Range...

Dave, Ashok M

2012-06-07

118

Prediction of Microporosity in Shrouded Impeller Castings  

SciTech Connect

The purpose of this Cooperative Research and Development Agreement (CRADA) between the Oak Ridge National Laboratory (ORNL) and Morris Bean and Company was to link computer models of heat and fluid flow with previously developed quality criteria for the prediction of microporosity in a Al-4.5% Cu alloy shrouded impeller casting. The results may be used to analyze the casting process design for the commercial production of 206 o alloy shrouded impeller castings. Test impeller castings were poured in the laboratory for the purpose of obtaining thermal data and porosity distributions. Also, a simulation of the test impeller casting was conducted and the results validated with porosity measurements on the test castings. A comparison of the predicted and measured microporosity distributions indicated an excellent correlation between experiments and prediction. The results of the experimental and modeling studies undertaken in this project indicate that the quality criteria developed for the prediction of microporosity in Al-4.5% Cu alloy castings can accurately predict regions of elevated microporosity even in complex castings such as the shrouded impeller casting. Accordingly, it should be possible to use quality criteria for porosity prediction in conjunction with computer models of heat and fluid flow to optimize the casting process for the production of shrouded impeller castings. Since high levels of microporosity may be expected to result in poor fatigue properties, casting designs that are optimized for low levels of microporosity should exhibit superior fatigue life.

Viswanathan, S. Nelson, C.D.

1998-09-01

119

Impeller deflection and modal finite element analysis.  

SciTech Connect

Deflections of an impeller due to centripetal forces are calculated using finite element analysis. The lateral, or out of plane, deflections are an important design consideration for this particular impeller because it incorporates an air bearing with critical gap tolerances. The target gap distance is approximately 10 microns at a rotational velocity of 2500 rpm. The centripetal forces acting on the impeller cause it deflect in a concave fashion, decreasing the initial gap distance as a function of radial position. This deflection is characterized for a previous and updated impeller design for comparative purposes. The impact of design options such as material selection, geometry dimensions, and operating rotational velocity are also explored, followed by a sensitivity study with these parameters bounded by specific design values. A modal analysis is also performed to calculate the impeller's natural frequencies which are desired to be avoided during operation. The finite element modeling techniques continue to be exercised by the impeller design team to address specific questions and evaluate conceptual designs, some of which are included in the Appendix.

Spencer, Nathan A.

2013-10-01

120

Answering thermodynamic questions with three-dimensional viscous flow calculations  

NASA Astrophysics Data System (ADS)

The use of three dimensional viscous flow calculations to understand losses and irreversibility in turbomachinery flows, and to show where inefficiency arises is discussed. An IBM 3032 computer and a Prandtl mixing length turbulence model were used to study centrifugal compressor impellers operating with steady, subsonic flow near their design point. For this class of flow, three dimensional viscous flow calculations can show boundary layer growth and accumulation in wake flow; tip leakage flow and mixing; work and loss distributions; and sources of loss production.

Moore, J.

121

Flow Pattern Characterization for a Centrifugal Impeller  

NASA Astrophysics Data System (ADS)

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.

Benavides, Efrén M.

2014-08-01

122

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

NASA Technical Reports Server (NTRS)

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.

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

1994-01-01

123

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

NASA Technical Reports Server (NTRS)

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.

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

1993-01-01

124

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

NASA Astrophysics Data System (ADS)

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.

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

2013-12-01

125

A magnetically suspended centrifugal pump. In vitro and in vivo assessment.  

PubMed

To overcome problems derived from the shaft within conventional centrifugal pumps, we have developed a new centrifugal pump, the magnetically suspended centrifugal pump (MSCP), which has no shaft and operates as a bearingless centrifugal pump. The impeller is suspended freely and centrally by magnetic force within the pump. Hemolysis tests were performed in comparison with the Biopump. Index of hemolysis and destruction of platelets were significantly lower in the MSCP than in the Biopump. Animal studies were designed to evaluate the durability and antithrombogenicity of the MSCP. Short-term animal studies were performed using two mongrel dogs. Left heart bypass was established with the MSCP. After 3 hr, the layer of thrombus adherent to the surface of the polycarbonate impeller impaired pumping efficiency. However, using the impeller coated with silicone, no thrombus was observed on the impeller after continuous pumping for 24 hr. In addition, long-term animal studies were performed using two sheep. Left heart bypass was established with the MSCP containing an impeller coated with silicone. In one sheep, the MSCP ran for 14 days without problems in pumping performance and showed no thrombus within the pump. In the other sheep, the MSCP ran for 15 days, and showed no thrombus on the impeller. During each experiment, plasma free hemoglobin levels were less than 15 mg/dl. The MSCP induced less hemolysis than did the Biopump, and the MSCP containing an impeller coated with silicone demonstrated the potential to run for 14 days without thrombus formation within the pump. PMID:8573822

Park, C H; Nishimura, K; Yamada, T; Mizuhara, H; Akamatsu, T; Tsukiya, T; Matsuda, K; Ban, T

1995-01-01

126

Submersible canned motor transfer pump  

DOEpatents

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.

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

127

Method for Reducing Pumping Damage to Blood  

NASA Technical Reports Server (NTRS)

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.

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

128

Optimization and Analysis of Centrifugal Pump considering Fluid-Structure Interaction  

PubMed Central

This paper presents the optimization of vibrations of centrifugal pump considering fluid-structure interaction (FSI). A set of centrifugal pumps with various blade shapes were studied using FSI method, in order to investigate the transient vibration performance. The Kriging model, based on the results of the FSI simulations, was established to approximate the relationship between the geometrical parameters of pump impeller and the root mean square (RMS) values of the displacement response at the pump bearing block. Hence, multi-island genetic algorithm (MIGA) has been implemented to minimize the RMS value of the impeller displacement. A prototype of centrifugal pump has been manufactured and an experimental validation of the optimization results has been carried out. The comparison among results of Kriging surrogate model, FSI simulation, and experimental test showed a good consistency of the three approaches. Finally, the transient mechanical behavior of pump impeller has been investigated using FSI method based on the optimized geometry parameters of pump impeller.

Hu, Sanbao

2014-01-01

129

Optimization and analysis of centrifugal pump considering fluid-structure interaction.  

PubMed

This paper presents the optimization of vibrations of centrifugal pump considering fluid-structure interaction (FSI). A set of centrifugal pumps with various blade shapes were studied using FSI method, in order to investigate the transient vibration performance. The Kriging model, based on the results of the FSI simulations, was established to approximate the relationship between the geometrical parameters of pump impeller and the root mean square (RMS) values of the displacement response at the pump bearing block. Hence, multi-island genetic algorithm (MIGA) has been implemented to minimize the RMS value of the impeller displacement. A prototype of centrifugal pump has been manufactured and an experimental validation of the optimization results has been carried out. The comparison among results of Kriging surrogate model, FSI simulation, and experimental test showed a good consistency of the three approaches. Finally, the transient mechanical behavior of pump impeller has been investigated using FSI method based on the optimized geometry parameters of pump impeller. PMID:25197690

Zhang, Yu; Hu, Sanbao; Zhang, Yunqing; Chen, Liping

2014-01-01

130

Calculating Flow-Angle Deviation in Rotary Pumps  

NASA Technical Reports Server (NTRS)

New mathematical formula calculates difference between angle of impeller blade and angle of flow. Formula used for inducers of mixed-flow pumps. With formula, calculations made more quickly and accurately than previously available formulas.

Meng, S. Y.; Furst, R. B.

1986-01-01

131

Analysis of Viscous Micropumps and Microturbines David DeCourtye  

E-print Network

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

Gad-el-Hak, Mohamed

132

Multiple discharge cylindrical pump collector  

DOEpatents

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.

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

1989-01-01

133

Dynamics of a high speed impeller - Analysis and experimental verification  

NASA Astrophysics Data System (ADS)

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.

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

1993-04-01

134

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

PubMed

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

Pai, Chi Nan; Shinshi, Tadahiko

2011-10-01

135

Microcomputer Analysis of Pumping System Performance  

E-print Network

produced by the pump for a given series computers, has been developed to permit the capacity, as well as the brake horsepower, analysis of pump operation based on descriptions efficiency, and net positive suction head. Pump of the piping system... to impeller peripheral velocity and head is proportional to the square of the peripheral velocity. Therefore. flow (Q) will vary directly with the change in speed (n). head (H) will vary as the square of the speed, and brake horsepower (BHP) will vary...

Bierschenk, J. L.; Schmidt, P. S.

136

Mathematical Modeling of Fluid Flow in a Water Physical Model of an Aluminum Degassing Ladle Equipped with an Impeller-Injector  

NASA Astrophysics Data System (ADS)

In this work, a 3D numerical simulation using a Euler-Euler-based model implemented into a commercial CFD code was used to simulate fluid flow and turbulence structure in a water physical model of an aluminum ladle equipped with an impeller for degassing treatment. The effect of critical process parameters such as rotor speed, gas flow rate, and the point of gas injection (conventional injection through the shaft vs a novel injection through the bottom of the ladle) on the fluid flow and vortex formation was analyzed with this model. The commercial CFD code PHOENICS 3.4 was used to solve all conservation equations governing the process for this two-phase fluid flow system. The mathematical model was reasonably well validated against experimentally measured liquid velocity and vortex sizes in a water physical model built specifically for this investigation. From the results, it was concluded that the angular speed of the impeller is the most important parameter in promoting better stirred baths and creating smaller and better distributed bubbles in the liquid. The pumping effect of the impeller is increased as the impeller rotation speed increases. Gas flow rate is detrimental to bath stirring and diminishes the pumping effect of the impeller. Finally, although the injection point was the least significant variable, it was found that the "novel" injection improves stirring in the ladle.

Gómez, Eudoxio Ramos; Zenit, Roberto; Rivera, Carlos González; Trápaga, Gerardo; Ramírez-Argáez, Marco A.

2013-04-01

137

Impeller Metrology for Pipeline Compressors Using Computed Radiography  

Microsoft Academic Search

A new, quantitative method is described to measure features in pipeline impellers using computed radiography (CR). This capability, with an accuracy approaching 5 mils, is required to optimize the impeller design for high efficiency. The large area coverage, simplicity, and high spatial resolution of CR are ideal for this application. A novel phantom and image processing algorithm chain was used

G. Nelson; T. Gordon; C. Bueno; D. Noonan; S. George; A. Mahesh; S. Korukonda; M. Fabbri; U. Cantelli; N. Marcucci

2006-01-01

138

Fluid forces on rotating centrifugal impeller with whirling motion  

NASA Technical Reports Server (NTRS)

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.

Shoji, H.; Ohashi, H.

1980-01-01

139

Incompressible Navier-Stokes calculations in pump flows  

NASA Astrophysics Data System (ADS)

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.

Kiris, Cetin; Chang, Leon; Kwak, Dochan

1993-07-01

140

Incompressible Navier-Stokes Calculations in Pump Flows  

NASA Technical Reports Server (NTRS)

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.

Kiris, Cetin; Chang, Leon; Kwak, Dochan

1993-01-01

141

Optimization of integrated impeller mixer via radiotracer experiments.  

PubMed

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

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

2014-01-01

142

Axial length influence on the performance of centrifugal impellers  

NASA Astrophysics Data System (ADS)

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).

Al-Zubaidy, S. N. J.

1992-12-01

143

Novel maglev pump with a combined magnetic bearing.  

PubMed

The newly developed pump is a magnetically levitated centrifugal blood pump in which active and passive magnetic bearings are integrated to construct a durable ventricular assist device. The developed maglev centrifugal pump consists of an active magnetic bearing, a passive magnetic bearing, a levitated impeller, and a motor stator. The impeller is set between the active magnetic bearing and the motor stator. The active magnetic bearing uses four electromagnets to control the tilt and the axial position of the impeller. The radial movement of the levitated impeller is restricted with the passive stability dependent upon the top stator and the passive permanent magnetic bearing to reduce the energy consumption and the control system complexity. The top stator was designed based upon a magnetic field analysis to develop the maglev pump with sufficient passive stability in the radial direction. By implementing this analysis design, the oscillating amplitude of the impeller in the radial direction was cut in half when compared with the simple shape stator. This study concluded that the newly developed maglev centrifugal pump displayed excellent levitation performance and sufficient pump performance as a ventricular assist device. PMID:15745134

Onuma, Hiroyuki; Murakami, Michiko; Masuzawa, Toru

2005-01-01

144

Submersible canned motor mixer pump  

DOEpatents

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.

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

1997-01-01

145

Submersible canned motor mixer pump  

DOEpatents

A mixer pump is described 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 there through, thereby resisting damage to and the interruption of the operation of the mixer pump. 10 figs.

Guardiani, R.F.; Pollick, R.D.

1997-10-07

146

Submersible canned motor transfer pump  

DOEpatents

A transfer pump is described which is 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 there through, 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. 17 figs.

Guardiani, R.F.; Pollick, R.D.; Nyilas, C.P.; Denmeade, T.J.

1997-08-19

147

Viscous Buckle Folding  

NSDL National Science Digital Library

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.

Resor, Phil

148

Mistuned Vibration of Radial Inflow Turbine Impeller  

NASA Astrophysics Data System (ADS)

This paper is concerned with the numerical prediction of impeller blade vibration due to excitation by the wake of nozzle guide vanes in turbochargers. This problem is particularly important as turbochargers are used in a broad range of operation conditions, leading to some unavoidable resonant frequencies. In the paper, first the unsteady pressure distributions on the rotor blades are analyzed and structural response analysis is performed for the excitation component with largest contribution to pressure fluctuation. In a parametric survey, pressure expansion ratio and inlet flow temperature are varied in order to investigate the impact on vibration response. Unsteady CFD+FEM prediction well explains the qualitative trends that appeared in experimental survey. The result also points out that a fluctuation in natural frequency among the blades of only a few percent may cause large magnification factors. Finally, adjustment of disk thickness is suggested as a measure to reduce the magnification factor and its effectiveness demonstrated numerically as well as experimentally.

Hattori, Hiroaki; Unno, Masaru; Hayashi, Masazumi

149

Research on 3-D discharge flow in a centrifugal impeller  

NASA Astrophysics Data System (ADS)

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.

Xi, Guang; Wang, Shangjin

1993-01-01

150

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

NASA Technical Reports Server (NTRS)

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.

Tatchell, D. G.

1979-01-01

151

Design of a Bearingless Blood Pump  

NASA Technical Reports Server (NTRS)

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.

Barletta, Natale; Schoeb, Reto

1996-01-01

152

Numerical Investigations of Slip Phenomena in Centrifugal Compressor Impellers  

NASA Astrophysics Data System (ADS)

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.

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

2013-03-01

153

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

154

Numerical simulation of impeller-volute interaction in centrifugal compressors  

Microsoft Academic Search

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

K. Hillewaert; R. A. Van den Braembussche

1999-01-01

155

Impeller Metrology for Pipeline Compressors Using Computed Radiography  

NASA Astrophysics Data System (ADS)

A new, quantitative method is described to measure features in pipeline impellers using computed radiography (CR). This capability, with an accuracy approaching 5 mils, is required to optimize the impeller design for high efficiency. The large area coverage, simplicity, and high spatial resolution of CR are ideal for this application. A novel phantom and image processing algorithm chain was used to demonstrate measurement repeatability of 99.9% (1 mil) using CR.

Nelson, G.; Gordon, T.; Bueno, C.; Noonan, D.; George, S.; Mahesh, A.; Korukonda, S.; Fabbri, M.; Cantelli, U.; Marcucci, N.

2006-03-01

156

Coiling of viscous jets  

NASA Astrophysics Data System (ADS)

A stream of viscous fluid falling from a sufficient height onto a surface forms a series of regular coils. I use a numerical model for a deformable fluid thread to predict the coiling frequency as a function of the thread's radius, the flow rate, the fall height, and the fluid viscosity. Three distinct modes of coiling can occur: viscous (e.g. toothpaste), gravitational (honey falling from a moderate height) and inertial (honey falling from a great height). When inertia is significant, three states of steady coiling with different frequencies can exist over a range of fall heights. The numerically predicted coiling frequencies agree well with experimental measurements in the inertial coiling regime.

Ribe, Neil M.

2004-11-01

157

A new magnetically suspended centrifugal pump: in vitro and preliminary in vivo assessment.  

PubMed

To overcome problems derived from the shaft within the conventional centrifugal pump, we have been developing a new centrifugal pump, namely a magnetically suspended centrifugal pump (MSCP), which has no shaft and operates as a noncontacting and bearingless pump. The impeller is suspended magnetically between the magnetic bearing and the driving motor. Hemolysis tests were performed in comparison with the Biopump (BP80, BioMedicus). The index of hemolysis (IH) was significantly lower in the MSCP than in the Biopump. In addition, a smaller gap in the MSCP induced lower hemolysis. In preliminary studies using mongrel dogs, the layer of thrombus adherent to the impeller was observed in a few hours, which impaired the pumping efficiency. However, by using an impeller coated with silicone, no aggregations of platelets or fibrin on the impeller were observed in 24 h of continuous pumping. In conclusion, the MSCP had a gentler influence on blood cells than the Biopump, and the impeller coated with silicone may contribute to the long-term pumping of the MSCP. PMID:8712956

Park, C H; Nishimura, K; Akamatsu, T; Tsukiya, T; Matsuda, K; Ban, T

1996-02-01

158

A Relevance Vector Machine-Based Approach with Application to Oil Sand Pump Prognostics  

PubMed Central

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

Hu, Jinfei; Tse, Peter W.

2013-01-01

159

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

PubMed

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

Hu, Jinfei; Tse, Peter W

2013-01-01

160

Viscous Hydraulic Jumps Submitted by  

E-print Network

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

Bush, John W.M.

161

Research on design multi-points performance curves of pump  

NASA Astrophysics Data System (ADS)

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.

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

2012-11-01

162

Effect of relative velocity distribution on efficiency and exit flow of centrifugal impellers  

NASA Astrophysics Data System (ADS)

A quasi-three-dimensional flow analysis proposed by Senoo and Nakase (1972) is applied in order to estimate the relative velocity distribution within a centrifugal impeller, assuming that the flow is both isentropic and inviscid. The relationship between relative velocity distribution, impeller efficiency, and meridional exit flow is experimentally investigated for the case of shrouded impellers having various relative velocity distributions. Analytical results are used to establish design criteria for the relative velocity distribution of centrifugal impellers.

Mishina, H.; Nishida, H.

1983-03-01

163

Numerical simulation of impeller-volute interaction in centrifugal compressors  

SciTech Connect

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.

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

1999-07-01

164

New concepts and new design of permanent maglev rotary artificial heart blood pumps.  

PubMed

According to tradition, permanent maglev cannot achieve stable equilibrium. The authors have developed, to the contrary, two stable permanent maglev impeller blood pumps. The first pump is an axially driven uni-ventricular assist pump, in which the rotor with impeller is radially supported by two passive magnetic bearings, but has one point contact with the stator axially at standstill. As the pump raises its rotating speed, the increasing hydrodynamic force of fluid acting on the impeller will make the rotor taking off from contacting point and disaffiliate from the stator. Then the rotor becomes fully suspended. The second pump is a radially driven bi-ventricular assist pump, i.e., an impeller total artificial heart. Its rotor with two impellers on both ends is supported by two passive magnetic bearings, which counteract the attractive force between rotor magnets and stator coil iron core. The rotor is affiliated to the stator radially at standstill and becomes levitated during rotation. Therefore, the rotor keeps concentric with stator during rotation but eccentric at standstill, as is confirmed by rotor position detection with Honeywell sensors. It concludes that the permanent maglev needs action of a non-magnetic force to achieve stability but a rotating magnetic levitator with high speed and large inertia can maintain its stability merely with passive magnetic bearings. PMID:16183322

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

2006-05-01

165

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

PubMed

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

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

2009-01-01

166

Effect of impeller speed on mechanical and dissolution properties of high-shear granules  

Microsoft Academic Search

Impeller speed is one of the most crucial process variables that affect the properties of the granules produced in a high-shear granulator. Several reports can be found in literature that discuss the influence of impeller speed on the granules size. For instance some researchers like Knight report an increase of granule size with impeller speed [1,2], while others (Scheaefer et

C. Mangwandi; M. J. Adams; M. J. Hounslow; A. D. Salman

2010-01-01

167

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

PubMed

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

Ungerman, Andrew J; Heindel, Theodore J

2007-01-01

168

Development and evaluation of antithrombogenic centrifugal pump: the Baylor C-Gyro Pump Eccentric Inlet Port Model.  

PubMed

The Baylor C-Gyro Pump Eccentric Inlet Port Models (C1E) have been developed aiming for a long-term centrifugal ventricular assist device (VAD) as well as a cardiopulmonary bypass pump. The eccentric inlet port models are characterized by their unique inlet port and secondary impeller vanes. An inlet female pivot bearing, which was fixed to a supporting bar in the prototype model, is directly embedded into the ceiling of the pump casing. An inlet port is then placed off-center to avoid the bearing area, and it is angled between 0 to 90 degrees from the upright position. In addition, small secondary vanes were incorporated into the impeller bottom to accelerate the washout flow behind the impeller. These features attained design objectives proposed for higher antithrombogenicity: a seal-less pump chamber, no stationary parts in the blood path, and acceleration of the secondary flow behind the impeller. The first in vivo experiment using C1E pumps showed excellent antithrombogenicity for up to 18 days when the experiment ceased due to severe infection in the calf. PMID:7998885

Ohara, Y; Makinouchi, K; Glueck, J; Sutherland, B; Shimono, T; Naito, K; Tasai, K; Orime, Y; Takatani, S; Nosé, Y

1994-09-01

169

VISCOUS CHARACTERICTICS ANALYSIS  

NASA Technical Reports Server (NTRS)

Current investigations of the hydrogen-fueled supersonic combustion ramjet engine have delineated several technological problem areas. One area, the analysis of the injection, turbulent mixing, and combusiton of hydrogen, requires the accurate calculation of the supersonic combustion flow fields. This calculation has proven difficult because of an interesting phenomena which makes possible the transition from supersonic to subsonic flow in the combustion field, due to the temperature transitions which occur in the flow field. This computer program was developed to use viscous characteristics theory to analyze supersonic combustion flow fields with imbedded subsonic regions. Intended to be used as a practical design tool for two-dimensional and axisymmetric supersonic combustor development, this program has proven useful in the analysis of such problems as determining the flow field of a single underexpanded hydrogen jet, the internal flow of a gas sampling probe, the effects of fuel-injector strut shape, and the effects of changes in combustor configuration. Both combustion and diffusive effects can significantly alter the wave pattern in a supersonic field and generate significant pressure gradients in both the axial and radial directions. The induced pressure, in turn, substantially influences the ignition delay and reaction times as well as the velocity distribution. To accurately analyze the flow fields, the effects of finite rate chemistry, mixing, and wave propagation must be properly linked to one another. The viscous characteristics theory has been used in the past to describe flows that are purely supersonic; however, the interacting pressure effects in the combustor often allow for the development of shock waves and imbedded subsonic regions. Numerical investigation of these transonic situations has required the development of a new viscous characteristics procedure which is valid within the subsonic region and can be coupled with the standard viscous characteristics procedure in the supersonic region. The basic governing equations used are the 'viscous-inviscid' equations, similar to those employed in higher-order boundary layer analyses, with finite rate chemistry terms included. In addition, the Rankine-Hugoniot and Prandtl-Meyer relations are used to compute shock and expansion conditions. The program can handle up to 20 simultaneous shock waves. Chemistry terms are computed for a 7-species 8-mechanism hydrogen-air reaction scheme. The user input consists of a physical description of the combustor and flow determination parameters. Output includes detail flow parameter values at selected points within the flow field. This computer program is written in FORTRAN IV for batch execution and has been implemented on a CDC CYBER 175 with a central memory requirement of approximately 114K (octal) of 60 bit words. The program was developed in 1978.

Jenkins, R. V.

1994-01-01

170

Raft river geothermal pump disassembly and inspection  

SciTech Connect

The disassembly and postoperation inspection of the Peerless geothermal water pump used in teh RRGE-1 well at the Raft River Geothermal Test Site are summarized. Disassembly was hampered by scale that froze some of the pump bearings onto the impeller shaft after operation ceased. The pump appeared otherwise in generally excellent condition after more than 1600 h running time in a geothermal environment. Most postoperation diameters of rotating parts were still within factory tolerance. The few out-of-tolerance bearing diameters could not be attributed to wear and could have been out of tolerance when received. This possibility points to a need for preoperation quality-control inspection of the bearings.

Van Treeck, R.

1983-02-01

171

Canned pump having a high inertia flywheel  

DOEpatents

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.

Veronesi, L.; Raimondi, A.A.

1989-12-12

172

Canned pump having a high inertia flywheel  

DOEpatents

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.

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

1989-01-01

173

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

NASA Technical Reports Server (NTRS)

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

Colding-Jorgensen, J.

1980-01-01

174

SSME Investment in Turbomachinery Inducer Impeller Design Tools and Methodology  

NASA Technical Reports Server (NTRS)

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.

Zoladz, Thomas; Mitchell, William; Lunde, Kevin

2010-01-01

175

INTELLIGENT PERFORMANCE CFD OPTIMISATION OF A CENTRIFUGAL IMPELLER  

Microsoft Academic Search

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

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

176

Solid dispersion in the slurry reactor with multiple impellers  

Microsoft Academic Search

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

O. P. Klenov; A. S. Noskov

177

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

Microsoft Academic Search

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.

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

178

Performance of small high pressure cryogenic pumps  

NASA Astrophysics Data System (ADS)

Two small cryogenic pumps have been made and tested for use in LO2/LH2 rocket-engine turbopumps. Both the pumps have a small impeller and are characterized by high speed and high delivery pressure. The main design characteristics of the pumps are as follows: rotational speeds 45,000 and 80,000 rpm, delivery pressures 24.6 and 26.0 MPa, and flow rates 0.016 and 0.0439 cu m/s, for LO2 and LH2 pumps, respectively. The efficiencies of the test pumps were compared with previously reported results, and the adiabatic efficiency (usually used for compressors or gas turbines) was investigated in more detail to demonstrate its applicability to cryogenic pumps.

Kamijo, K.; Watanabe, M.; Hasegawa, S.

179

Viscous exchange flows  

NASA Astrophysics Data System (ADS)

Gravitationally driven exchange flows of viscous fluids with different densities are analysed theoretically and investigated experimentally within a horizontal channel. Following initiation from rest when there is a vertical boundary dividing the two fluids, the denser fluid slumps under the less dense along the underlying boundary, while the less dense fluid intrudes along the upper boundary. The motion is driven by the pressure gradients associated with the density differences between the two fluids, resisted by viscous stresses, and mathematically modelled by a similarity solution that depends on the ratio of the viscosities of the two fluids. When the viscosity of the less dense fluid is much smaller than the viscosity of the denser fluid, the shape of the interface between the fluids varies rapidly close to the upper boundary and depends weakly on the viscosity ratio within the interior of the flow. Matched asymptotic expansions are employed in this regime to determine the shape of the interface and the rates of its propagation along the boundaries. The similarity solutions are shown to be linearly stable and thus are expected to represent the intermediate asymptotics of the flow. Experiments confirm the similarity form of solutions and demonstrate close agreement with the theoretical predictions when the viscosities of the fluids are comparable, but exhibit some discrepancies when the viscosities differ more substantially. It is suggested that these discrepancies may be due to mixing between the fluids close to the boundaries, which is induced by the no-slip boundary condition. Exchange flows within porous domains are also investigated to determine the shape of the interface as a function of the ratio of the viscosities of the two fluids and using asymptotic analysis, this shape is determined when this ratio is much larger, or smaller, than unity.

Matson, Gary P.; Hogg, Andrew J.

2012-02-01

180

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

NASA Astrophysics Data System (ADS)

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.

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

2012-11-01

181

Computational fluid dynamics analysis to establish the design process of a centrifugal blood pump: second report.  

PubMed

To establish an efficient design process for centrifugal blood pumps, the results of computational fluid dynamics (CFD) analysis were compared to the results of flow visualization tests and hemolysis tests, using the Nikkiso centrifugal blood pump. CFD analysis revealed that the radial gap greatly affected the shear stress in the outlet diffuser. The hemolysis study also indicated a similar tendency. To see the flow behind the impeller, we conducted a comparative study between models with and without washout holes using the CFD technique. CFD analysis indicated that flow and pressure distributions behind the impeller were different between both models, and a particle was observed to remain longer behind the impeller in the model without washout holes. In the future, CFD analysis could be a useful tool for developing blood pumps in comparison to flow visualization tests and hemolysis tests. PMID:10463504

Miyazoe, Y; Sawairi, T; Ito, K; Konishi, Y; Yamane, T; Nishida, M; Asztalos, B; Masuzawa, T; Tsukiya, T; Endo, S; Taenaka, Y

1999-08-01

182

Advanced direct-design procedure for centrifugal impellers  

NASA Astrophysics Data System (ADS)

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.

Al-Zubaidy, Sarum N. J.

1993-02-01

183

Micropump for viscous liquids and muds  

NASA Astrophysics Data System (ADS)

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.

Schwesinger, Norbert; Bechtel, Sasha

1998-09-01

184

Numerical simulation of 3D turbulent flow through an entire stage in a multistage centrifugal pump  

NASA Astrophysics Data System (ADS)

A three-dimensional turbulent flow through a multistage centrifugal pump is numerically simulated using a commercial CFD software package. The simulation and analysis include flow fields in rotating impeller and stationary diffuser and is completed in a multiple reference frame. The standard k ? turbulence model is applied. The analysis of the simulation reveals that the reverse flows exist in the zone near the impeller exit and diffuser entrance, resulting in asymmetric and unsteady flow field. There is a considerable interference on the velocity field at the impeller exit due to the interaction between impeller blades and diffuser vanes. The hydraulic performance is connected and evaluated with the 3D computational flow field. The current computation is verified by comparing predicted and measured head.

Huang, Si; Islam, Mohammed F.; Liu, Pengfei

2006-06-01

185

Noise reduction for centrifugal fan with non-isometric forward-swept blade impeller  

Microsoft Academic Search

To reduce the noise of the T9-19No.4A centrifugal fan, whose impeller has equidistant forward-swept blades, two new impellers\\u000a with different blade spacing were designed and an experimental study was conducted. Both the fan’s aerodynamic performance\\u000a and noise were measured when the two redesigned impellers were compared with the original ones. The test results are discussed\\u000a in detail and the effect

Jianfeng Ma; Datong Qi; Yijun Mao

2008-01-01

186

Gas–liquid flow in stirred reactors: Trailing vortices and gas accumulation behind impeller blades  

Microsoft Academic Search

In a gas–liquid stirred reactor, gas tends to accumulate in low-pressure regions behind the impeller blades. Such gas accumulation significantly alters impeller performance characteristics. We have computationally investigated gas–liquid flow generated by a Rushton (disc) turbine. Rotating Rushton turbine generates trailing vortices behind the blades, which influence the gas accumulation in the impeller region. Characteristics of these trailing vortices were

Vivek V. Ranade; Vaibhav R. Deshpande

1999-01-01

187

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

NASA Technical Reports Server (NTRS)

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.

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

1973-01-01

188

Numerical analysis of the internal flow field in screw centrifugal blood pump based on CFD  

NASA Astrophysics Data System (ADS)

As to the impeller blood pump, the high speed of the impeller, the local high shear force of the flow field and the flow dead region are the main reasons for blood damage. The screw centrifugal pump can effectively alleviate the problems of the high speed and the high shear stress for the impeller. The softness and non-destructiveness during the transfer process can effectively reduce the extent of the damage. By using CFD software, the characteristics of internal flow are analyzed in the screw centrifugal pump by exploring the distribution rules of the velocity, pressure and shear deformation rate of the blood when it flows through the impeller and the destructive effects of spiral blades on blood. The results show that: the design of magnetic levitation solves the sealing problems; the design of regurgitation holes solves the problem of the flow dead zone; the magnetic levitated microcirculation screw centrifugal pump can effectively avoid the vortex, turbulence and high shear forces generated while the blood is flowing through the pump. Since the distribution rules in the velocity field, pressure field and shear deformation rate of the blood in the blood pump are comparatively uniform and the gradient change is comparatively small, the blood damage is effectively reduced.

Han, W.; Han, B. X.; Y Wang, H.; Shen, Z. J.

2013-12-01

189

Transmission vibration viscous damper  

SciTech Connect

A manual transmission is described comprising an input shaft adapted to be clutched to the crankshaft of an internal combustion engine, the input shaft having an input gear integral; the input gear forms with peripheral teeth and has a concentric axial bore formed as an integral part of the input shaft; a transmission output shaft supported at its forward end by journal means located in the axial bore; the output shaft having a speed gear formed with peripheral teeth journalled thereon, a countershaft having an axis of rotation parallel with the axis of rotation of the output shaft. The improvement wherein the countershaft has a viscous fluid damper coupling supported thereon. The coupling comprises a first driven gear journalled on the countershaft, and the first drive gear has peripheral teeth in constant meshed engagement with the input gear peripheral teeth. A second driven gear is fixed on the countershaft for rotation. The second driven gear has peripheral teeth in constant meshed engagement with the speed gear peripheral teeth, a diametrical through bore extending through the countershaft intermediate the first and second driven gears. Each first and second driven gears formed with a set of longitudinally extending mirror image axial teeth are arranged concentrically about axis of rotation. The sets of axial teeth are sized to mesh in a loose fitting manner defining predetermined interconnected clearance spaces between the sets of axial teeth.

Filkins, T.J.

1987-07-07

190

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

E-print Network

??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… (more)

Lusardi, Christopher (Christopher Dean)

2012-01-01

191

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

NASA Astrophysics Data System (ADS)

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.

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

2013-12-01

192

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

E-print Network

Committee: Dr. Peter Jenkins Experiments have been carried out in order to determine the effects of different inlet geometries on the onset of suction recircu- lation and its associated power consumption in axial flow pumps. The experiments were... 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...

Alpan, Kenan

2012-06-07

193

TRANSIENT BEHAVIOR OF THE VISCOUS MICROPUMP  

Microsoft Academic Search

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

M. Abdelgawad; I. Hassan; N. Esmail

2004-01-01

194

Experiment of a centrifugal pump during changing speed operation  

NASA Astrophysics Data System (ADS)

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.

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

2012-11-01

195

Blood Pump Bearing System  

NASA Technical Reports Server (NTRS)

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.

Aber, Gregory S. (Inventor)

2000-01-01

196

Blood Pump Bearing System  

NASA Technical Reports Server (NTRS)

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.

Aber, Gregory S. (Inventor)

1999-01-01

197

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

NASA Astrophysics Data System (ADS)

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

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

2013-12-01

198

Numerical simulation of an axial blood pump.  

PubMed

The axial blood pump with a magnetically suspended impeller is superior to other artificial blood pumps because of its small size. In this article, the distributions of velocity, path line, pressure, and shear stress in the straightener, the rotor, and the diffuser of the axial blood pump, as well as the gap zone were obtained using the commercial software, Fluent (version 6.2). The main focus was on the flow field of the blood pump. The numerical results showed that the axial blood pump could produce 5.14 L/min of blood at 100 mm Hg through the outlet when rotating at 11,000 rpm. However, there was a leakage flow of 1.06 L/min in the gap between the rotor cylinder and the pump housing, and thus the overall flow rate the impeller could generate was 6.2 L/min. The numerical results showed that 75% of the scalar shear stresses (SSs) were less than 250 Pa, and 10% were higher than 500 Pa within the whole pump. The high SS region appeared around the blade tip where a large variation of velocity direction and magnitude was found, which might be due to the steep angle variation at the blade tip. Because the exposure time of the blood cell at the high SS region within the pump was relatively short, it might not cause serious damage to the blood cells, but the improvement of blade profile should be considered in the future design of the axial pump. PMID:17584481

Chua, Leok Poh; Su, Boyang; Lim, Tau Meng; Zhou, Tongming

2007-07-01

199

Arbitrary surface flank milling of fan, compressor, and impeller blades  

SciTech Connect

It is generally conceived that a blade surface is flank millable if it can be closely approximated by a ruled surface; otherwise the slow machining process of point milling has to be employed. However, the authors have now demonstrated that the ruled surface criterion for flank milling is neither necessary nor sufficient. Furthermore, many complex arbitrary surfaces typical of the blades in fans, axial compressors, and centrifugal impellers in aviation gas turbines are actually closely flank millable and can be rendered exactly flank millable with one or more passes per surface often without sacrificing, indeed usually with gain, in performance.

Wu, C.Y. [Pratt and Whitney Canada Incorporated, Longueuil, Quebec, (Canada). Design Engineering

1995-07-01

200

Characterization of a centrifugal pump in He II  

NASA Technical Reports Server (NTRS)

As part of an effort to determine the feasibility of helium transfer in space, a centrifugal pump was tested in He II at a variety of flow rates, pump speeds, and fluid temperatures. The pump, which has a straight bladed impeller 6.86 cm in diameter, generated a maximum pressure rise of 15 kPa and a maximum flow rate of 22 g/s for the conditions of the test. Pump performance seems to be independent of fluid temperature and is in good agreement with the values predicted by the manufacturer. Over the range of flow coefficients, the measured maximum efficiency is around 50 percent. Cavitation is observed in the pump and is thought to be highly dependent on the local heating of the helium in the pump. Preliminary measurements of the noise spectra of the pump suggest a possible mechanism to predict the onset of cavitation.

Weisend, J. G., II; Van Sciver, S. W.

1988-01-01

201

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

Microsoft Academic Search

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

Mert Cevik; Oguz Uzol

2011-01-01

202

Impelling and Inhibiting Forces in the Perpetration of Intimate Partner Violence  

E-print Network

Impelling and Inhibiting Forces in the Perpetration of Intimate Partner Violence Eli J. Finkel Northwestern University The huge corpus of research identifying risk factors for intimate partner violence (IPV strong violence-impelling forces, which lead the individual to experience action tendencies toward IPV

Reber, Paul J.

203

Hybrid plasma deposition and milling for an aeroengine double helix integral impeller made of superalloy  

Microsoft Academic Search

Superalloy integral impeller is a vital functional component of an aeroengine, but it is very difficult to manufacture if using the traditional five-axis NC machining method because of its complex free surfaces. Lamination deposition technology using high energy beams can overcome these difficulties and can be used to directly manufacture complex superalloy double helix integral impellers. However, subsequent re-machining should

Xiong Xinhong; Zhang Haiou; Wang Guilan; Wang Guoxian

2010-01-01

204

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

E-print Network

An analysis is developed for a compressible bulk-flow model of the leakage path between a centrifugal compressor's impeller shroud and housing along the front and back side of the impeller. This is an extension of analysis performed first by Childs...

Gupta, Manoj Kumar

2005-08-29

205

Studies on impeller type, impeller speed and air flow rate in an industrial scale flotation cell. Part 3: Effect on superficial gas velocity  

Microsoft Academic Search

Superficial gas velocity was measured at different locations in a 2.8 m3 portable industrial scale sub-aeration flotation cell, treating zinc cleaner feed at Hellyer Concentrator in Tasmania, Australia. The cell was fitted in turn with four different impeller-stator systems, and operated over a range of air flow rates and impeller speeds. Superficial gas velocity values ranged from 0.29 cm\\/sec to

B. K. Gorain; J.-P. Franzidis; E. V. Manlapig

1996-01-01

206

Studies on impeller type, impeller speed and air flow rate in an industrial scale flotation cell — Part 1: Effect on bubble size distribution  

Microsoft Academic Search

Bubble size distributions were measured at different locations in a 2.8 m3 portable industrial scale sub-aeration flotation cell, treating zinc cleaner feed in the Hellyer Concentrator in Tasmania, Australia. The cell was fitted in turn with four different impeller-stator systems, and operated over a range of air flow rates and impeller speeds. The mean bubble size was found to increase

B. K Gorain; J.-P Franzidis; E. V Manlapig

1995-01-01

207

Studies on impeller type, impeller speed and air flow rate in an industrial scale flotation cell. Part 4: Effect of bubble surface area flux on flotation performance  

Microsoft Academic Search

The metallurgical performance of a 2.8m3 portable industrial scale flotation cell was measured when treating zinc cleaner feed at Hellyer concentrator in Tasmania, Australia. The cell was fitted in turn with four different impeller-stator systems and operated over a wide range of air flow rates and impeller speeds. Bubble size, gas holdup and superficial gas velocity were measured at each

B. K. Gorain; J. P. Franzidis; E. V. Manlapig

1997-01-01

208

Studies on impeller type, impeller speed and air flow rate in an industrial scale flotation cell part 2: Effect on gas holdup  

Microsoft Academic Search

Gas holdup was measured at different locations in a 2.8 m3 portable industrial scale subaeration flotation cell, treating zinc cleaner feed at Hellyer Concentrator in Tasmania, Australia. The cell was fitted in turn with four different impeller-stator systems, and operated over a range of air flow rates and impeller speeds. The gas holdup was found to increase with increase in

B. K. Gorain; J.-P. Franzidis; E. V. Manlapig

1995-01-01

209

Computational fluid dynamics analysis of a centrifugal blood pump with washout holes.  

PubMed

The authors studied avoidance of coagulation occurrence using computational fluid dynamics (CFD) analysis from the fluid dynamical point of view. Concerning centrifugal pumps, blood coagulation sometimes occurs at the region behind the impeller where the flow is generally stagnant. Therefore, we conducted a thorough study with the specimen pump with and without washout holes, mocking up the Nikkiso HPM-15. As the result, the model with washout holes indicated that the fluid rotates rapidly at the vicinity of the shaft and generates washout effects near the stationary rear casing. On the other hand, the model without washout holes showed that fluid cannot be quickly shipped out of the area behind the impeller and rotates mildly around the shaft. To clarify the moving relations between the impeller and the fluid, validation studies by comparing the results of CFD analysis and flow visualization experiments are ongoing; thus far, the studies show that CFD results are similar to the results from flow visualization experiments. PMID:10971255

Tsukamoto, Y; Ito, K; Sawairi, T; Konishi, Y; Yamane, T; Nishida, M; Masuzawa, T; Tsukiya, T; Endo, S; Taenaka, Y

2000-08-01

210

Influence of impeller shroud forces on turbopump rotor dynamics  

NASA Technical Reports Server (NTRS)

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.

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

1993-01-01

211

Trailing edge noise reduction in a backward-curved impeller  

NASA Astrophysics Data System (ADS)

Motorized impellers are used in many air-moving applications including room circulation, duct flow, roof and wall exhaust, and cooling of electronic components in cabinets. These fans are backward-curved centrifugal blowers that operate with no volute casing. These fans radiate broadband noise due to turbulence ingestion and trailing edge (TE) noise generating mechanisms. Considered here are trailing edge noise generation and its reduction in a typical motorized impeller. The sound power of the subject fans is measured in an acoustically transparent test plenum according to ANSI Standard S12.11-1987. Two different serrated TE treatments are designed. The designs assume that a turbulent boundary layer exists at the blade TE, but the actual fan Reynolds number based on chord length is transitional. Therefore, to assure that a turbulent boundary layer exists at the TE, two different inlet turbulators are implemented. These trip the blade boundary layer to a turbulent state. Reported are the effects of the TE serrations and turbulators acting individually on the fan noise, along with the synergistic effects of using them in combinations. Up to 6 dBA of noise reduction is observed when the two are used together. [Work supported by Nortel Networks.

Lauchle, Gerald C.

2002-05-01

212

Numerical calculation and optimal design of a hot water circulation pump  

NASA Astrophysics Data System (ADS)

The problem of hot water circulation pump head shortage is common. In this paper, numerical simulation technology, combined with orthogonal experimental design, was used to research optimal designs to improve the hot water circulation pump's head. CFX software was used to calculate the flow field in the pump, and the head-flow rate curve could be achieved. The accuracy of CFD was validated through comparison between numerical and experimental data. According to the experience, the number of impeller blades, thickness and width of impeller outlet were changed to improve the hot water circulation pump's head. A three factors and level values of model pump orthogonal experiment was designed, and numerical simulation of whole flow field based on CFX was adopted to implement the orthogonal experiment. Finally, the best designed scheme for model pump was obtained. The analysis of results indicates that the head of hot water circulation pump has increased by 7.77% at rated conditions. The distribution in impellers' internal flow field is symmetrical, and accords with the law of fluids flow in the common centrifugal pump.

Zhang, H.; Y Kong, F.; Xia, B.; Tan, L. W.

2013-12-01

213

Scaling properties of viscous fingering  

E-print Network

We present a study of viscous fingering using the Volume Of Fluid method and a central injection geometry, assuming a Laplacian field and a simple surface tension law. As in experiments we see branched structures resulting from the Saffman-Taylor instability. We find that the area $A$ of a viscous-fingering cluster varies as a simple power law $A \\sim L^{\\alpha}$ of its interface length $L$. Our results are compared to previously published simulations in which the viscosity of the invading fluid is vanishing. We find differences in exponent $\\alpha$ and in the appearance of detached droplets and bubbles.

Lagrée, Bertrand; Bondino, Igor; Josserand, Christophe; Popinet, Stéphane

2014-01-01

214

Plastic pumps combat battery acid with minimum maintenance  

SciTech Connect

GNB Inc. in Zanesville, Ohio, is a volume manufacturer of wet cell batteries in a wide range of sizes and ampere ratings for automotive and industrial applications. Vertical pumps operating in pits and storage tanks were rapidly attacked by the sulfuric acid and had to be replaced every few months. Pumps of a more acid-resistant material were needed to reduce excessive downtime, maintenance and original equipment costs. Pump materials options such as stainless steels, exotic metals and various non-metallics were evaluated for resistance to the dilute acid. The final choice was a cantilever-type sump pump with all wetted parts, including the impeller, casing and vertical piping of relatively insert polypropylene. The one-piece stainless steel motor/impeller shaft is protected by a heavy-wall plastic sheath which is easy to replace if necessary. The shaft is totally supported at the upper end by two oversize motor bearings, and a restriction bushing of low fraction Teflon fluoro-plastic, positioned just above the impeller, assures smooth, steady operation. There are no submerged bearings to burn out should the pump run dry. The polypropylene sump pumps have an average service life of ten years with the battery acid. Currently, three of the pumps are mounted in 4' deep pits and three with tail pipes are installed in vertical storage tanks to transfer the acid at 40-50 gpm to day tanks for the cell filling stations. The bearingless pumps have required very little maintenance since the first units were installed more than 12 years ago.

Jones, J.; Gaines, A.

1986-12-01

215

Cryogenic Viscous Compressor Development and Modeling for the ITER Vacuum System  

SciTech Connect

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

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

216

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

NASA Astrophysics Data System (ADS)

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.

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

2012-11-01

217

Laminar flow control - viscous simulation  

Microsoft Academic Search

Laminar flow control which offers the possibility of major reductions in aircraft drag is described. The theoretical background for the possible stabilizations of the laminar boundary layer due to shaping, suction and cooling is presented. The effects of vehicle and environmental factors on the implementation of that technology are examined. Viscous simulation is the technology of adjusting boundary layer conditions

E. Reshotko

1984-01-01

218

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

NASA Astrophysics Data System (ADS)

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.

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

2013-12-01

219

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

Microsoft Academic Search

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

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

2012-01-01

220

Optimization of a Continuous Hybrid Impeller Mixer via Computational Fluid Dynamics  

PubMed Central

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

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

2014-01-01

221

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

PubMed

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

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

2014-01-01

222

Development of a portable bridge-to-decision blood pump.  

PubMed

We are developing an axial-flow pump with a cylindrical-impeller without airfoils. In the mock experiments of HA02 model a pressure of 13.3 kPa was obtained at a rotational speed of 12500 rpm and flow of 5L/min. The obtained pressure with HA02 was almost double than an airfoil-type impeller. The 2D analysis of hydrodynamic bearings for the pump revealed that a section with 3 or more arcs is stable with respect to angular position, and a minimum bearing gap of 100 µm can be attained at a design bearing gap of 150 µm and at a groove depth of 100 µm. PMID:24110291

Yamane, T; Kitamura, K

2013-01-01

223

Development of a Compact Maglev Centrifugal Blood Pump Enclosed in a Titanium Housing  

NASA Astrophysics Data System (ADS)

A compact centrifugal blood pump consisting of a controlled two-degrees-of-freedom radial magnetic bearing and a brushless DC motor enclosed in a titanium housing has been developed for use as an implantable ventricular assist device. The magnetic bearing also supports axial and angular motions of the impeller via a magnetic coupling. The top housing is made of pure titanium, while the impeller and the stator are coated with pure titanium and Ti-6Al-7Nb, respectively, to improve the biocompatibility of the pump. The combination of pure titanium and titanium alloy was chosen because of the sensitivity of eddy current type displacement sensors through the intervening conducting wall. The dimensions of the pump are 69.0 mm in diameter and 28.5 mm in height. During a pump performance test, axial shifting of the impeller due to hydraulic forces led to variations in the rotational positioning signal, causing loss of control of the rotational speed. This problem was solved by conditioning the rotational positioning signal. With a flow rate of 5 l/min against a head pressure of 100 mmHg, the power consumption and efficiency of the pump were 5.5 W and 20%, respectively. Furthermore, the hemolysis of the blood pump was 43.6% lower when compared to that of a commercially available pump.

Pai, Chi Nan; Shinshi, Tadahiko; Asama, Junichi; Takatani, Setsuo; Shimokohbe, Akira

224

Numerical analysis of the flow field in the pump chamber of a centrifugal pump with back blades  

NASA Astrophysics Data System (ADS)

Black blade is frequently used as a non-contact seal structure in centrifugal pumps transporting solid-liquid two-phase flow. However, it will disturb the flow in the pump and affect the pump performance. Numerical simulation for 3D turbulence in whole flow passage of a centrifugal pump with back blades was carried out based on RANS method, with SST k-? turbulence model and SIMPLEC algorithm. Calculation for a similar pump without back blades was also carried out as a comparison. Boundary condition was improved due to the existence of back blade. The influence of back blades on the flow field was analysed qualitatively for three typical conditions. Meanwhile the leakage rate was calculated for several conditions and the effect of back blades was discussed. According to the results, compared with the condition without back blades, it could be seen that back blade apparently changed the flow state in the front chamber, improved near the front shroud and worsened near the pump cover. Velocity was increased and more fluid, which flowed into the front chamber from the pump cover side, flowed back to the spiral casing from the impeller shroud side. With the increase of discharge, the absolute value of leakage rate first went up and then dropped, as a consequence of the combination of two factors, discharge and differential pressure between the impeller outlet and inlet. The seal effect of back blades is most obvious under small discharge condition, and the leakage loss diminished as discharge increased.

Cao, L.; Wang, Z. W.; Y Luo, Y.; Liu, M.

2013-12-01

225

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

NASA Astrophysics Data System (ADS)

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.

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

2013-12-01

226

Fjords in viscous fingering: selection of width and opening scale  

SciTech Connect

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.

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

2008-01-01

227

Cavitation improvement of double suction centrifugal pump HPP Fuhren  

NASA Astrophysics Data System (ADS)

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.

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

2012-11-01

228

Competition between anisotropic viscous fingers  

NASA Astrophysics Data System (ADS)

We consider viscous fingers created by injection of low viscosity fluid into the network of capillaries initially filled with a more viscous fluid (motor oil). Due to the anisotropy of the system and its geometry, such a setup promotes the formation of long-and-thin fingers which then grow and compete for the available flow, interacting through the pressure field. The interaction between the fingers is analyzed using the branched growth formalism of Halsey and Leibig (Phys. Rev. A 46, 7723, 1992) using a number of simple, analytically tractable models. It is shown that as soon as the fingers are allowed to capture the flow from one another, the fixed point appears in the phase space, corresponding to the asymptotic state in which the growth of one of the fingers in hindered by the other. The properties of phase space flows in such systems are shown to be remarkably insensitive to the details of the dynamics.

Pecelerowicz, M.; Budek, A.; Szymczak, P.

2014-09-01

229

Development of a centrifugal pump with improved antithrombogenicity and hemolytic property for chronic circulatory support.  

PubMed

A centrifugal pump with a unique structure has been developed for chronic support. The pump is driven by a magnetic coupling and has no rotating shaft, no seal around the rotating part, and a balancing hole at the center of the impeller and the thrust bearing. The pump was improved in stepwise fashion to realize good antithrombogenicity and low hemolysis. The first pump, the National Cardiovascular Center (NCVC)-0, had an impeller with 4 rectangular and curved vanes; 6 triangularly shaped curved vanes were employed in the second model, the NCVC-1, to reduce trauma to the blood. In the third design, the NCVC-2, the central hole was enlarged, and the thrust bearing shoulder was rounded so that blood washing was enhanced around the impeller; stream lines also were smoothed for improved antithrombogenicity. The hemolytic property of the device was evaluated in vitro with heparinized fresh goat blood; hemolysis indexes of the NCVC-0, -1, and -2 were 0.05, 0.01, and 0.006 g per 100 L, respectively. Antithrombogenicity of the pumps was examined in animal experiments as a left heart bypass device in goals weighing 52-75 kg. Six NCVC-0 pumps were driven for 14 to 33 (22.0 +/- 7.6) days in goats receiving the antiplatelet drug cilostazol orally. Four NCVC-1 pumps ran for 1 to 80 (28.5 +/- 30.6) days with the same drug regimen in 2 cases and with no anticoagulation therapy in 2 cases. After 3 preliminary 1-week tests of NCVC-2 pumps in animals, the pump was installed in 3 goats; 2 pumps were still running on the 182nd and 58th pumping day. Intracorporeal implantation also was attempted successfully. The results indicate that this pump has promising features for chronic support although longer term and additional evaluations are necessary. PMID:8817945

Taenaka, Y; Wakisaka, Y; Masuzawa, T; Tatsumi, E; Toda, K; Miyazaki, K; Eya, K; Baba, Y; Nakatani, T; Ohno, T; Nishimura, T; Takano, H

1996-06-01

230

Development of design methods for a centrifugal blood pump with a fluid dynamic approach: results in hemolysis tests.  

PubMed

The purpose of this study was to examine the relationship between local flow conditions and the hemolysis level by integrating hemolysis tests, flow visualization, and computational fluid dynamics to establish practical design criteria for centrifugal blood pumps with lower levels of hemolysis. The Nikkiso centrifugal blood pump was used as a standard model, and pumps with different values of 3 geometrical parameters were tested. The studied parameters were the radial gap between the outer edge of the impeller vane and the casing wall, the position of the outlet port, and the discharge angle of the impeller vane. The effect of a narrow radial gap on hemolysis was consistent with no evidence that the outlet port position or the vane discharge angle affected blood trauma in so far as the Nikkiso centrifugal blood pump was concerned. The radial gap should be considered as a design parameter of a centrifugal blood pump to reduce blood trauma. PMID:10463503

Masuzawa, T; Tsukiya, T; Endo, S; Tatsumi, E; Taenaka, Y; Takano, H; Yamane, T; Nishida, M; Asztalos, B; Miyazoe, Y; Ito, K; Sawairi, T; Konishi, Y

1999-08-01

231

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

E-print Network

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 ...

Everitt, Jonathan (Jonathan Neil)

2014-01-01

232

Forced response of a centrifugal compressor stage due to the impeller-diffuser interaction  

E-print Network

The unsteady pressure field experienced by a centrifugal compressor stage can be dominated by of the impeller-diffuser interaction. The energy of the unsteady field, under certain aerodynamic and structural conditions, is ...

Walton, Edward James

2014-01-01

233

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

E-print Network

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 ...

Lusardi, Christopher (Christopher Dean)

2012-01-01

234

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

NASA Technical Reports Server (NTRS)

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.

Moore, Joan G.; Moore, John

1992-01-01

235

Effect of the collector tube profile on Pitot pump performances  

NASA Astrophysics Data System (ADS)

The pitot pump is composed of the rotating casing with the impeller channel and the pitot tube type collector as the discharge line. The radial impeller feeds water to the rotating casing. The water rotating together with the casing is caught by the stationary pitot tube type collector, and then discharges to the outside. This type pump, as the extra high head pump, is provided mainly for boiler feed systems, and has been designed by trial and error. To optimize the pump profiles, it is desirable to investigate not only performances but also internal flow conditions. This paper discusses experimentally and numerically the relation between the pump performances and the flow conditions in the rotating casing. The moderately larger dimensions of the collector make the pump head and the discharge high with the higher hydraulic efficiency. The flow in the casing is almost the forced vortex type whose velocity is in proportion to the radius but the core velocity is affected with the drag force of the stationary collector. Based upon the above results, the profile of the pitot tube type collector was optimized with the numerical simulation.

Komaki, K.; Kanemoto, T.; Sagara, K.; Umekage, T.

2013-12-01

236

Hydraulic design and performance analysis of low specific speed centrifugal pump  

NASA Astrophysics Data System (ADS)

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.

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

2012-11-01

237

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

NASA Technical Reports Server (NTRS)

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.

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

1956-01-01

238

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

Microsoft Academic Search

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

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

2010-01-01

239

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

Microsoft Academic Search

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

John R. Fagan; Sanford Fleeter

1991-01-01

240

CFD based rotordynamic coefficients for labyrinth seals and impeller leakage paths  

E-print Network

CFD BASED ROTORDYNAMIC COEFFICIENTS FOR LABYRINTH SEALS AND IMPELLER SHROUD LEAKAGE PATHS A Thesis by AVI JIT BHATTACHARYA Submitted to the Oflice of Graduate Studies of Texas ASM University in partial fulfillment of the requirements... for the degree of MASTER OF SCIENCE December 1997 Major Subject: Mechanical Engineering CFD BASED ROTORDYNAMIC COEFFICIENTS FOR LABYRINTH SEALS AND IMPELLER SHROUD LEAKAGE PATHS A Thesis AVI JIT BHATTACHARYA Submitted to Texas ARM University in partial...

Bhattacharya, Avijit

2012-06-07

241

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

NASA Astrophysics Data System (ADS)

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.

Cho, Leesang; Lee, Seawook; Cho, Jinsoo

242

Effect of flow rate on loss mechanisms in a backswept centrifugal impeller  

NASA Astrophysics Data System (ADS)

Detailed measurements of the three velocity components, total, and static pressures on five measurement planes without a low speed shrouded backswept centrifugal impeller are presented. A comparison is made between the design flowfield and the flowfields for both below and above design flow rates. The flow is dominated by a passage vortex that rotates in the opposite direction to the impeller. This vortex develops in the inducer, is strongest in the axial to radial bend, and then decays toward the outlet. The vortex is also most prominent at the lowest flow rate and is responsible for stabilizing the shroud boundary layer and hence reducing the large losses associated with the separation of this boundary layer in radial impellers. At the outlet, the wake is located on the shroud at all flow rates, but tends to be spread more evenly across the shroud than is the case in a radial machine. The impeller efficiency is also generally found to be spread more evenly across the shroud than is the case in a radial machine. The impeller efficiency is also generally found to be higher at lower flow rates in contrast to observations for radial impellers.

Farge, Talib Z.; Johnson, Mark W.

1992-06-01

243

Reduced-order modeling for mistuned centrifugal impellers with crack damages  

NASA Astrophysics Data System (ADS)

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.

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

2014-12-01

244

Design considerations of volute geometry of a centrifugal blood pump.  

PubMed

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

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

2005-12-01

245

Experiment Study of the Internal Flow in Centrifugal Pump  

NASA Astrophysics Data System (ADS)

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.

Liu, D.; Wang, C. L.

2011-09-01

246

Development and industrial application of the 'all-over-controlled vortex distribution method' for designing radial and mixed flow impellers  

Microsoft Academic Search

A detailed experimental exploration is conducted for the 3D impeller-model stages and multistage compressors designed by the 'all-over-controlled' vortex-distribution method for centrifugal and mixed-flow compressors. Excellent performance is obtained. Since the blade generation is conducted simultaneously with the mean s(2) flow surface analysis, the design time for an impeller is fully controllable, ensuring the possibility of enlarging these 3D impellers'

S. J. Wang; M. J. Yuan; G. Xi; S. X. Liu; D. T. Qi; X. J. Chai

1992-01-01

247

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

NASA Technical Reports Server (NTRS)

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.

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

1992-01-01

248

Development and industrial application of the 'all-over-controlled vortex distribution method' for designing radial and mixed flow impellers  

NASA Astrophysics Data System (ADS)

A detailed experimental exploration is conducted for the 3D impeller-model stages and multistage compressors designed by the 'all-over-controlled' vortex-distribution method for centrifugal and mixed-flow compressors. Excellent performance is obtained. Since the blade generation is conducted simultaneously with the mean s(2) flow surface analysis, the design time for an impeller is fully controllable, ensuring the possibility of enlarging these 3D impellers' range of application. The original method is presently improved in order to allow the design of small axial-length impellers.

Wang, S. J.; Yuan, M. J.; Xi, G.; Liu, S. X.; Qi, D. T.; Chai, X. J.

1992-06-01

249

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

NASA Astrophysics Data System (ADS)

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.

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

2013-04-01

250

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

PubMed

The centrifugal blood pump with a magnetically suspended impeller has shown its superiority as compared to other artificial heart pumps. However, there is still insufficient understanding of fluid mechanics related issues in the clearance gap. The design nature of the pump requires sufficient washout in the clearance between the impeller and the stationary pump housing inner surface. In this study, numerical simulations were carried out to investigate the flow fields in the gap of the Kyoto-NTN centrifugal blood pump. The flow patterns in the gap region of the blood pump were presented and regions of high and low velocity were identified. It was found that the radial velocity of the blood in the gap was closely related to the pressure distribution at the exit of the impeller, both the highest pressure gradient and the highest radial velocity in the gap occurred at an angular position of 170 degrees . The mass flow rate in the gap was estimated to be 25.2% of the pump outflow, which is close to the measurement results of a five times enlarged test pump. The wall shear stresses on the gap surface were found to be over 21 Pa and below 300 Pa, which is correspondingly higher than the threshold of thrombi formation and is lower than the shearing threshold of red blood cells. Comparison of the 1 : 1 simulation model with the measurement results on a five times enlarged test pump indicates that there are some differences in the resulting radial velocity distributions in the gap and thus the washout mechanism. Two symmetrical high washout regions at both the cutwater and splitter plate were observed in the simulation instead of a single washout region at the splitter plate found in the experimental study. This may be due to the scaling effect of the enlarged test pump; also the medium used in the experiment is different from the simulation. PMID:16048478

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

2005-08-01

251

Fundamental Viscous Solutions or `Transient Ossenlets' Associated with a Body Manoeuvring in a Viscous Fluid  

Microsoft Academic Search

A viscous boundary element method involving a convolution-integral formulation is developed to determine directly the fluid actions and velocity flow field associated with a body manoeuvring in a viscous fluid. The proposed general approach is analogous to a potential flow singularity distribution panel method with the singularity replaced by a fundamental viscous solution. From the developed nonlinear mathematical model based

W. G. Price; Ming-Yi Tan

1992-01-01

252

Injector pump  

Microsoft Academic Search

An injection pump consists of a barrel and plunger-type tubing pump for pumping liquid from a deep borehole through tubing while injecting a treating liquid down through a hollow sucker rod. Just above the traveling valve is a blender coupling means. The hollow passage through the sucker rod communicates through an injector pipe to the top of a shallow bore

A. L. Dunn; H. Hill

1978-01-01

253

Heat pumps  

NSDL National Science Digital Library

What electric heating system is the most efficient in moderate climates? This reading, part of a series about the future of energy, introduces students to the modern heat pump. Students read about the efficiency of heat pumps and the three types currently being used in homes. A simple explanation of how a heat pump works is offered. Copyright 2005 Eisenhower National Clearinghouse

Project, Iowa P.

2004-01-01

254

Why viscous fluids adhere to rugose walls  

Microsoft Academic Search

The main purpose of this paper is to justify rigorously the following assertion: A viscous fluid cannot slip on a wall covered by microscopic asperities because, due to the viscous dissipation, the surface irregularities bring to rest the fluid particles in contact with the wall. In mathematical terms, this corresponds to an asymptotic property established in this paper for any

Juan Casado-D??az; Enrique Fernández-Cara; Jacques Simon

2003-01-01

255

Viscous-pendulum damper suppresses structural vibrations  

NASA Technical Reports Server (NTRS)

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.

Reed, W. H., III

1964-01-01

256

Viscous fingering in shear thickening silica suspensions  

Microsoft Academic Search

We make an experimental study of the viscous fingering behavior of air displacing shear thickening silica suspensions in linear Hele-Shaw cells with different cell gaps as a function of the injection pressure. The imposed shear rate defined by the ratio of the finger tip velocity and the half of a cell gap, at which the onset of the viscous fingering

Naoki Kagei; Daisuke Kanie; Masami Kawaguchi

2005-01-01

257

Studies on impeller type, impeller speed and air flow rate in an industrial scale flotation cell. Part 5: validation of k-S b relationship and effect of froth depth  

Microsoft Academic Search

A previous investigation carried out by the authors at the Hellyer concentrator, using a 3 m3 cell fitted with four different impellers treating plant zinc cleaner feed ore, suggested a linear correlation between flotation rate constant k and bubble surface area flux Sb. The relationship between k and Sb was found to be independent of impeller type. This paper describes

B. K. Gorain; T. J. Napier-Munn; J.-P. Franzidis; E. V. Manlapig

1998-01-01

258

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

NASA Astrophysics Data System (ADS)

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.

Tan, Lei; Cao, Shu-Liang; Wang, Yu-Ming; Zhu, Bao-Shan

2012-01-01

259

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

PubMed

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

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

2013-01-01

260

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

NASA Astrophysics Data System (ADS)

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 at both operating points show regions near the impeller exit with a significant velocity deficit on the shroud surface characteristic of the traditional jet-wake structure observed in many centrifugal compressors. At design, the maximum velocity deficit occurs at a location 70 percent of the passage width from the pressure to the suction surface. At the incipient stall point, the maximum velocity deficit occurs in the shroud suction surface corner, with the data indicating reverse flow.

Fagan, John R.; Fleeter, Sanford

1991-06-01

261

Closing the gap in series scale up of high shear wet granulation process using impeller power and blade design  

Microsoft Academic Search

This paper investigates the use of impeller work combined with an understanding of the significance of the impeller power inflection point during granulation to monitor, control, and scale up high shear wet granulation processes in the pharmaceutical industry. High shear wet granulations were carried out in a series of PMA Fielder granulators (25, 65, 150, and 300-L) with a geometric

Gossett A. Campbell; Donald J. Clancy; Jinzhou X. Zhang; Manish K. Gupta; Choon K. Oh

2011-01-01

262

Flow visualization as a complementary tool to hemolysis testing in the development of centrifugal blood pumps.  

PubMed

With a 250% scaled-up pump model, high speed video camera, and argon ion laser light sheet, flow patterns related to hemolysis were visualized and analyzed with 4 frame particle tracking software. Different flow patterns and shear distributions were clarified by flow visualization for pumps modified to have different hemolysis levels. A combination of in vitro hemolysis tests, flow visualization, and CFD analysis suggested a close relationship between hemolysis and high shear caused by small impeller/casing gaps. Because arbitrary cross sections can be illuminated by laser light sheet, flow visualization is a useful tool in finding locations related to hemolysis in the design process of rotary blood pumps. PMID:9609344

Yamane, T; Asztalos, B; Nishida, M; Masuzawa, T; Takiura, K; Taenaka, Y; Konishi, Y; Miyazoe, Y; Ito, K

1998-05-01

263

Properly choose mechanical agitators for viscous liquids  

SciTech Connect

High-viscosity mixing applications occur in most chemical process industries (CPI) plants. High-viscosity applications occur in the production of food, paint, drilling mud, and greases, to name a few. Mixing can occur in pipeline systems with motionless mixers, or in vessels using mechanical agitators, depending on the application and the process requirements. A wide variety of both motionless mixers and mechanical agitators is available to handle specific mixing problems and fluid types. This article gives an overview of designing the most commonly used agitator for blending applications: a top-entering agitator with a single shaft. The agitator can be equipped with multiple turbine-style impellers of different design, or with helical-ribbon or anchor-style impellers to optimize the agitator for the specific application and blending problem on hand. Although turbulent blending will be briefly discussed here also, this article will focus on blending in the laminar and transitional regimes. Also, the authors will discuss the special requirements for blending non-newtonian fluids, with and without yield stress. They first discuss the flow patterns and applicability of different impeller types and then present some design guidelines.

Bakker, A.; Gates, L.E.

1995-12-01

264

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

Microsoft Academic Search

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.

Qubo Li; Janusz Piechna; Norbert Müller

2011-01-01

265

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

E-print Network

-called "actuator-disk" theory (Church, 1944) in the turbomachinery community, which is a rather primitive flow analysis tool. Moore and Moore (1981) analyzed the three-dimensional flow field inside a centrifugal impeller using a partially parabolized flow... momentum leads to a spiral-like flow path downstream from the impeller, a constant-angle spiral emitting from the trailing edge was taken to represent the wake centerline. As a result, the wake center became a natural extension of the vane mean camber...

Hlavaty, Steven Todd

2012-06-07

266

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

NASA Astrophysics Data System (ADS)

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.

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

2013-12-01

267

Centrifugal blood pump for temporary ventricular assist devices with low priming and ceramic bearings.  

PubMed

A new model of centrifugal blood pump for temporary ventricular assist devices has been developed and evaluated. The design of the device is based on centrifugal pumping principles and the usage of ceramic bearings, resulting in a pump with reduced priming (35 ± 2 mL) that can be applied for up to 30 days. Computational fluid dynamic (CFD) analysis is an efficient tool to optimize flow path geometry, maximize hydraulic performance, and minimize shear stress, consequently decreasing hemolysis. Initial studies were conducted by analyzing flow behavior with different impellers, aiming to determine the best impeller design. After CFD studies, rapid prototyping technology was used for production of pump prototypes with three different impellers. In vitro experiments were performed with those prototypes, using a mock loop system composed of Tygon tubes, oxygenator, digital flow meter, pressure monitor, electronic driver, and adjustable clamp for flow control, filled with a solution (1/3 water, 1/3 glycerin, 1/3 alcohol) simulating blood viscosity and density. Flow-versus-pressure curves were obtained for rotational speeds of 1000, 1500, 2000, 2500, and 3000 rpm. As the next step, the CFD analysis and hydrodynamic performance results will be compared with the results of flow visualization studies and hemolysis tests. PMID:24219168

Leme, Juliana; da Silva, Cibele; Fonseca, Jeison; da Silva, Bruno Utiyama; Uebelhart, Beatriz; Biscegli, José F; Andrade, Aron

2013-11-01

268

CFD applications in pump flows  

NASA Astrophysics Data System (ADS)

The objective of the proposed paper is to develop a computational procedure that solves incompressible Navier-Stokes equations for pump flows. 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. As a benchmark problem, the flow through the Rocketdyne inducer is numerically simulated. A coarse grid solution is obtained with a single zone by using an algebraic turbulence model. In multi-zone fine grid computation, a one-equation Baldwin-Barth turbulence model is utilized. Numerical results are compared with experimental measurements and a good agreement is found between the two. The resulting computer code is then applied to the flow analysis inside a two-stage fuel pump impeller operating at 80 percent, 100 percent, and 120 percent of design flow.

Kiris, Cetin; Chang, Liang; Kwak, Dochan

1992-07-01

269

CFD applications in pump flows  

NASA Technical Reports Server (NTRS)

The objective of the proposed paper is to develop a computational procedure that solves incompressible Navier-Stokes equations for pump flows. 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. As a benchmark problem, the flow through the Rocketdyne inducer is numerically simulated. A coarse grid solution is obtained with a single zone by using an algebraic turbulence model. In multi-zone fine grid computation, a one-equation Baldwin-Barth turbulence model is utilized. Numerical results are compared with experimental measurements and a good agreement is found between the two. The resulting computer code is then applied to the flow analysis inside a two-stage fuel pump impeller operating at 80 percent, 100 percent, and 120 percent of design flow.

Kiris, Cetin; Chang, Liang; Kwak, Dochan

1992-01-01

270

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

SciTech Connect

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.

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

1995-12-08

271

Gyro-effect stabilizes unstable permanent maglev centrifugal pump.  

PubMed

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

Qian, Kun-Xi

2007-03-01

272

Microfluidic origami for point-of-care extraction of nucleic acids from viscous samples  

Microsoft Academic Search

We present a low-cost microfluidic origami device for point-of-care extraction of bacterial DNA from raw viscous samples – a challenge for conventional microfluidic systems. The core idea is a novel method for sequencing arbitrarily complex chemical and physical processing steps through sequential folding of 2D surfaces. This folding creates temporary paper fluidic circuits substituting capillary flow for pumps, and folding

A. V. Govindarajan; S. Ramachandran; G. D. Vigil; P. Yager; K. F. Bohringer

2011-01-01

273

In vivo evaluation of centrifugal blood pump for cardiopulmonary bypass-Spiral Pump.  

PubMed

The Spiral Pump (SP), a centrifugal blood pump for cardiopulmonary bypass (CPB), has been developed at the Dante Pazzanese Institute of Cardiology/Adib Jatene Foundation laboratories, with support from Sintegra Company (Pompeia, Brazil). The SP is a disposable pump with an internal rotor-a conically shaped fuse with double entrance threads. This rotor is supported by two ball bearings, attached to a stainless steel shaft fixed to the housing base. Worm gears provide axial motion to the blood column, and the rotational motion of the conically shaped impeller generates a centrifugal pumping effect, improving pump efficiency without increasing hemolysis. In vitro tests were performed to evaluate the SP's hydrodynamic performance, and in vivo experiments were performed to evaluate hemodynamic impact during usual CPB. A commercially available centrifugal blood pump was used as reference. In vivo experiments were conducted in six male pigs weighing between 60 and 90 kg, placed on CPB for 6 h each. Blood samples were collected just before CPB (T0) and after every hour of CPB (T1-T6) for hemolysis determination and laboratory tests (hematological and biochemical). Values of blood pressure, mean flow, pump rotational speed, and corporeal temperature were recorded. Also, ergonomic conditions were recorded: presence of noise, difficulty in removing air bubbles, trouble in installing the pump in the drive module (console), and difficulties in mounting the CPB circuit. Comparing the laboratory and hemolysis results for the SP with those of the reference pump, we can conclude that there is no significant difference between the two devices. In addition, reports made by medical staff and perfusionists described a close similarity between the two devices. During in vivo experiments, the SP maintained blood flow and pressure at physiological levels, consistent with those applied in cardiac surgery with CPB, without presenting any malfunction. Also, the SP needed lower rotational speed to obtain average blood flow and pressure, compared with the reference pump. PMID:24251773

da Silva, Cibele; da Silva, Bruno Utiyama; Leme, Juliana; Uebelhart, Beatriz; Dinkhuysen, Jarbas; Biscegli, José F; Andrade, Aron; Zavaglia, Cecília

2013-11-01

274

Heart Pump Design for Cleveland Clinic Foundation  

NASA Technical Reports Server (NTRS)

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.

2005-01-01

275

Breakup of viscous liquid sheets  

SciTech Connect

In many industrial processes, it is desirable to use a spray of drops rather than a bulk liquid. Examples of applications include gas turbines, industrial furnaces, diesel and gasoline engines, cooling sprays, and crop sprays. A study of the breakup of planar viscous liquid sheets subjected to gas flow on both sides were conducted. A linear spatial stability analysis was used to determine the instability wave characteristics. The analysis included the effects of liquid properties such as viscosity, density, and surface tension; the gas was treated as inviscid. Dispersion relations were obtained relating the wave growth rates to the frequency and other flow variables. The wave characteristics were determined by numerical solution of the governing dispersion relations for a wide range of operating conditions. In all cases, the gas velocity was found to be destabilizing; increases in the liquid density, viscosity, and surface tension were all found to have stabilizing effects. When the liquid sheet was exposed to unequal gas velocities, the wave propagation characteristics were found to be altered from the case of equal gas velocities.

Witherspoon, W.; Parthasarathy, R.N. [Univ. of Oklahoma, Norman, OK (United States). School of Aerospace and Mechanical Engineering

1996-10-01

276

Saddle-node bifurcation of viscous profiles  

PubMed Central

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

Achleitner, Franz; Szmolyan, Peter

2012-01-01

277

Wrinkling and sagging of viscous sheets  

E-print Network

This thesis explores the wrinkling and sagging behavior of thin viscous Newtonian sheets and filaments motivated by analogous scenarios in elasticity. These problems involve dynamic free boundaries and geometric nonlinearities ...

Teichman, Jeremy Alan, 1975-

2002-01-01

278

Suppression of secondary flows in a double suction centrifugal pump with different loading distributions  

NASA Astrophysics Data System (ADS)

Secondary flow is one of the main reasons for low efficiency in double suction centrifugal pump. In a 3-D inverse design method, the pump blade could be designed by a specified loading distribution to control the flow field in pump. In order to study the influence of loading distribution on secondary flow of a double suction centrifugal pump, the external characteristics and the internal flow field of the pump with three kinds of loading distributions are analysed by using CFD approach. According to the simulation results, it is found that the form of fore-loading distribution at shroud and aft-loading distribution at hub could improve the optimal efficiency and broaden the high efficiency area of the pump. Furthermore, the secondary flow in impeller exit region and volute could be significantly suppressed if the slope of loading distribution curve of shroud is set to be -0.7.

Leng, H. F.; Wang, F. J.; Zhang, Z. C.; Yao, Z. F.; Zhou, P. J.

2013-12-01

279

Investigation of the flow performance of a nutating blood pump by computational fluid dynamics.  

PubMed

In centrifugal blood pumps, blood is moved into a circular path with the help of an impeller. In a nutating pump, the nutating body takes over the role of the impeller. Since the nutating body itself does not rotate, this pump needs no seal, no blood contacting, and no magnetic bearings. To examine the suitability of the nutating pump principle for mechanical heart assist, the flow performance of different nutating pump models was investigated by computational fluid dynamics. The geometrical parameters of the pump were varied and flow-pressure curves were calculated for 12 models at different rotation frequencies. All models showed satisfactory flow-pressure curves. One model was computed minutely at 1 flow configuration to examine shear stresses within the fluid. A flow of 5 L/min and a frequency of 3,300 rotations per min (rpm) resulted in a differential pressure of 85 mm Hg. The maximum shear stress in the fluid at this flow was estimated to be 193 Pa which is considered to be an acceptable value for a blood pump. PMID:11952514

Sartori-Montecroce, Oliver; Goubergrits, Leonid; Affeld, Klaus

2002-04-01

280

Optimal Navier-Stokes Design of Compressor Impellers Using Evolutionary Computation  

Microsoft Academic Search

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

Ernesto Benini

2003-01-01

281

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

Microsoft Academic Search

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.

D. S. Musgrave

1979-01-01

282

Vortex design of a diagonal flow impeller with high specific speed  

Microsoft Academic Search

The 'vortex design' method applied to an axial flow compressor stage has been extended to a diagonal flow impeller with high specific speed. For a given type of vortex flow, the through flow problem is solved by the streamline curvature method, and a blade element is determined on the basis of this solution. However, for any vortex type except free

Yoshihisa Kamada; Sumio Yamaguchi; Kazuto Sasaki; Masahiro Inoue

1986-01-01

283

Experimental evaluation of the flow field inside an open faced impeller  

E-print Network

. It was also concluded that the velocity field was not fully two-dimensional in nature. This was believed to be a result of the 90° turn that the fluid endures as it enters the impeller inlet from the suction pipe....

Berchane, Nader Samir

2005-02-17

284

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

E-print Network

is ultimately electrically insulating (with electromagnetic properties of vacuum). Studies have considered is that the critical magnetic Reynolds number value for the onset of dynamo action must be lowered as much as possible - c.f. figure 1(a). The cylinder radius R is 97 mm and its length is 323 mm. The impellers have

Boyer, Edmond

285

Influence of operating conditions and impeller design on the continuous manufacturing of food foams  

Microsoft Academic Search

The influence of impeller design and operating conditions on the continuous manufacture of food foams was studied in a narrow gap mechanically stirred unit using a model food. Quality and texture of foams were characterised on the basis of density, bubble size and rheological measurements. Mixing mechanisms were investigated using residence time distribution (RTD) experiments. The results show that mean

Rajeev K. Thakur; Ch. Vial; G. Djelveh

2003-01-01

286

Developments in Impeller/Seal Secondary Flow Path Modeling for Dynamic Force Coefficients and Leakage  

NASA Technical Reports Server (NTRS)

This paper highlights bulk flow and CFD-based models prepared to calculate force and leakage properties for seals and shrouded impeller leakage paths. The bulk flow approach uses a Hir's based friction model and the CFD approach solves the Navier Stoke's (NS) equation with a finite whirl orbit or via analytical perturbation. The results show good agreement in most instances with available benchmarks.

Palazzolo, Alan; Bhattacharya, Avijit; Athavale, Mahesh; Venkataraman, Balaji; Ryan, Steve; Funston, Kerry

1997-01-01

287

Instigating, Impelling, and Inhibiting Factors in Aggression Erica B. Slotter and Eli J. Finkel  

E-print Network

of aggression, such as verbal, relational, or sexual aggression.) Craig Anderson and colleagues have soughtCH 2 1 I3 Theory: Instigating, Impelling, and Inhibiting Factors in Aggression Erica B. Slotter and Eli J. Finkel Northwestern University Interpersonal aggression is prevalent and disturbing

Reber, Paul J.

288

Investigation of the viscous resistance components of catamaran forms  

Microsoft Academic Search

Research into the breakdown of resistance components of catamaran hull forms has been carried out over a number of years. The components consist of viscous and wave resistance as well as viscous and wave resistance interference. Significant investigation of wave resistance has been carried out. Less effort, however, has been dedicated to determining viscous resistance and viscous interference resistance, which

I. Ketut Aria Pria Utama

1999-01-01

289

Fluorescent image tracking velocimetry of the Nimbus AxiPump.  

PubMed

High shear rates and extended residence times causing hemolysis and platelet activation can develop in an assist pump or cannula when inferior flow conditions exist. The high volume output of a miniature axial flow pump presents challenges in avoiding these adverse conditions. To assess the hemodynamics within the continuous flow Nimbus Axi-Pump, vector flow fields inside a translucent inflow cannula and a modified 12 mm AxiPump were mapped. Fluorescent image tracking velocimetry was used to track the motion of neutrally buoyant fluorescent particles (30 microns) using pulsed laser light, high resolution video cameras, and computer image analysis. An acrylic pump housing and cannula were integrated into a mock circulatory loop filled with a Newtonian, optically clear blood analog fluid. The flow parameters were controlled to yield known, physiologic loading conditions, including varying degrees of pulsatility. Cannula flow visualization results exhibited critical recirculation patterns at the bend. These results will be used to further optimize the design of the inflow. Particle impact was seen at the pump inlet in the inducer region of the rotor. Very good attachment of flow from the rotor to stator was observed when the pump operated at normal operating speeds. Intermittent regurgitant flow fields were evident in the presence of increased pulsatility and low pump speed. These results have lead to improvements in impeller design and speed control criteria to avoid potential deleterious flows. PMID:8268616

Kerrigan, J P; Shaffer, F D; Maher, T R; Dennis, T J; Borovetz, H S; Antaki, J F

1993-01-01

290

Effects of scaling on centrifugal blood pumps.  

PubMed

Experimental studies on the effects of scaling on the performance of centrifugal blood pumps were conducted in a closed-loop test rig. For the prototype, eight different impellers of the same outer diameter of 25 mm were tested at 1,500, 2,000, and 2,500 revolutions per minute (rpm) using blood analog as fluid medium. This corresponds to Reynolds numbers (Re) of 25,900, 34,500, and 43,200, respectively. The results indicated that the nondimensional pump characteristic is a function of Re. This is understandable since the typical operating Re for centrifugal blood pumps is less than 100,000. Thus, the effects of scaling cannot be ignored for centrifugal blood pumps. Experiments on a 5x scaled-up model have also indicated that the scaled-up model is more efficient than the prototype model. Our results showed that in the range of Re tested, the nondimensional head versus flow curve is a function of Re to the power of approximately 0.25. It is observed that the nondimensional head versus flow is a function of diameter ratio to the power of 0.2. PMID:12406160

Wong, Yew Wah; Chan, Weng Kong; Yu, S C M; Chua, Leok Poh

2002-11-01

291

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

NASA Technical Reports Server (NTRS)

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.

Pampreen, R. C.

1977-01-01

292

Effect of the NACA Injection Impeller on the Mixture Distribution of a Double-row Radial Aircraft Engine  

NASA Technical Reports Server (NTRS)

For the normal range of engine power the impeller provided marked improvement over the standard spray-bar injection system. Mixture distribution at cruising was excellent, maximum cylinder temperatures were reduced about 30 degrees F, and general temperature distribution was improved. The uniform mixture distribution restored the normal response of cylinder temperature to mixture enrichment and it reduced the possibility of carburetor icing, while no serious loss in supercharger pressure rise resulted from injection of fuel near the impeller outlet. The injection impeller also furnished a convenient means of adding water to the charge mixture for internal cooling.

Marble, Frank E.; Ritter, William K.; Miller, Mahlon A.

1946-01-01

293

Centrifugal Pump Test Bed: A Senior Capstone Project  

NSDL National Science Digital Library

A centrifugal pump test bed was designed, built and tested for the undergraduate mechanical engineering thermal fluids laboratory at Western Kentucky University. This project was funded through the Undergraduate Senior Project Grant Program sponsored by the American Society of Heating, Refrigeration, and Air Conditioning Engineers, Inc. (ASHRAE) and is primarily intended for instructional situations. The project was executed over a two-semester Mechanical Engineering Senior Project design sequence, with a three-member student team planning the project design during the fall semester and executing the project construction and testing during the spring. The final system delivered uses two 1.0 horsepower pumps that can generate a range of volumetric flows and a piping system capable of varied impedances and flow paths. A useful innovation by the team was the capability of modifying pump impeller diameter, as well as flow paths. Existing hands-on laboratory courses now have a centrifugal pump test bed to demonstrate the full complement of pump similitude: series and parallel configurations, rotational speed effects, and varied impeller size. During the senior design course sequence, the students generated a design and selected critical components in the pump demonstration bed to provide the desired capabilities, executed the project construction demonstrating their ability to work together as a team, managed the project and maintained a schedule within time and fiscal budgetary constraints, and finally implemented appropriate testing of the final system through an experimental test plan to assure that the desired quality was achieved. This paper will detail project outcomes and faculty observations of the process and assessment of student work.

Choate, Robert; Lenoir, Joel; Schmaltz, Kevin

2009-09-16

294

Mechanics of viscous vortex reconnection  

NASA Astrophysics Data System (ADS)

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.

Hussain, Fazle; Duraisamy, Karthik

2011-02-01

295

Self-Oscillations (Surging) of a Single-Stage Centrifugal Pump in the Cavitation Regime and Their Damping  

NASA Astrophysics Data System (ADS)

The self-oscillations (surging) of a single-stage centrifugal pump working in a hydraulic system in the cavitation regime before the stall of the water feed were investigated. The character of change in these oscillations with change in the value of the acoustic capacitance positioned at the input of the pump was determined. The damping of the indicated self-oscillations with the use of an acoustic liquid damper connected to the hydraulic system was investigated. The impossibility of realization of a model of cavitation self-oscillations for a single-stage impeller pump was substantiated.

Gotsulenko, V. V.; Gotsulenko, V. N.

2013-07-01

296

Process for upgrading a heavy viscous hydrocarbon  

SciTech Connect

A process for upgrading a heavy viscous hydrocarbon, for example, rendering a heavy viscous crude pipelinable, includes visbreaking, distillation and solvent extraction steps. A heavy viscous hydrocarbon is fed through the visbreaker which forms a feed to the distillation step. A heavier fraction from distillation is fed to a solvent extraction unit which produces a fraction which contains resin. At least a portion of the resin containing fraction separated in the solvent extraction unit is recycled and combined with the feed which is to be subjected to visbreaking so that the total yield of products, residual and gas-free, is increased. The recycled resin reduces the tendency of the asphaltenes to separate from the oil and thereby reduces the tendency to lay down coke in the visbreaker; this allows higher conversion to upgraded liquid products.

Lutz, I.H.

1984-06-12

297

Numerical Simulation of Viscous Accretion Disks  

NASA Astrophysics Data System (ADS)

A two-dimensional numerical hydrodynamics code is developed to model viscous accretion discs, employing the method of smoothed particle hydrodynamics. The effective shear viscosity present in the code is evaluated. Using a polytropic equation of state, models of self-gravitating accretion disks are evolved with a range of physical parameters, including viscosity. From these models it is found that a characteristic mass accretion rate, constant with time, tends to be maintained by the accretion disks, and that mass accretion is inversely proportional to the strength of the local shear viscous force. This is a consequence of the damping effect of local viscous forces upon the global non-axisymmetric modes that primarily drive accretion in these disks. In addition, the formation of satellites is observed in models which also develop a dominating m=1 tidal mode. The relevance of these satellites to planet formation is speculated.

Drimmel, Ronald

1995-12-01

298

Initial in vivo experience of the VentrAssist implantable rotary blood pump in sheep.  

PubMed

VentrAssist (VentrAssist Division, Ventracor Ltd., Chatswood, NSW, Australia) has developed an implantable centrifugal blood pump with an integrated rotor and impeller that is hydrodynamically suspended. Bench testing has been used to assess the performance of the pump under a broad range of operating conditions. This study examined the performance of the pump in vivo up to 90 days implantation. Pumps were implanted via a left lateral thoracotomy. The inflow cannula was inserted at the apex of the left ventricle. The outflow cannula was anastomosed to the descending thoracic aorta. Eighteen implants were performed. Poor recovery from surgery was the main cause of early study termination. These studies demonstrate the suitability of the animal model for evaluation of the VentrAssist rotary blood pump. Further in vivo studies prior to preclinical trials are in progress. PMID:12534709

van der Meer, Anita L; James, Natalie L; Edwards, Glenn A; Esmore, Donald S; Rosenfeldt, Franklin L; Begg, John D; Woodard, John C

2003-01-01

299

A flow visualization study of centrifugal blood pumps developed for long-term usage.  

PubMed

We have developed centrifugal pumps for long-term circulatory assistance, with the final goal of a completely implantable ventricular assist device or total artificial heart. The previous model, NCVC-0, was characterized by a nonseal design and few flow-stagnating parts and acquired high durability and antithrombogenicity. To improve its pumping performance, NCVC-0 was modified. In the new model, NCVC-1, the profile shape of the impeller was changed from flat to conical, the number of vanes from 4 to 6, and the vane entrance angle from 30 degrees to 60 degrees. A flow visualization study performed by means of a combination of the polystyrene tracer method and the light-cutting method indicated decreased flow turbulence between vanes in NCVC-1, which corresponded well with the increased pumping performance. Flow visualization is a useful method to evaluate the design elements that are closely related to the pumping performance of a centrifugal blood pump. PMID:8507164

Araki, K; Taenaka, Y; Masuzawa, T; Inoue, K; Nakatani, T; Kinoshita, M; Akagi, H; Baba, Y; Matsuo, Y; Sakaki, M

1993-05-01

300

Simultaneous viscous-inviscid coupling via transpiration  

SciTech Connect

In viscous-inviscid coupling analysis, the direct coupling technique and the inverse coupling technique are commonly adopted. However, stability and convergence of the algorithms derived are usually very unsatisfactory. Here, by using the transpiration technique to simulate the effect of the displacement thickness, a new simultaneous coupling method is derived. The integral boundary layer equations and the full potential equation are chosen to be the viscous-inviscid coupled system. After discretization, the Newton-Raphson technique is proposed to solve the coupled nonlinear system. Several numerical results are used to demonstrate the accuracy and efficiency of the proposed method. 15 refs., 23 figs.

Yiu, K.F.C.; Giles, M.B. [Oxford Univ. Computing Lab. (United Kingdom)] [Oxford Univ. Computing Lab. (United Kingdom)

1995-09-01

301

Viscous shock profiles and primitive formulations  

NASA Technical Reports Server (NTRS)

Weak solutions of hyperbolic systems in primitive (non-conservation) form for which a consistent conservation form exists are considered. It is shown that primitive formulations, shock relations are not uniquely defined by the states to either side of the shock but also depend on the viscous path connecting the two. Scheme-dependent high order correction terms are derived that enforce consistent viscous shock profiles. The resulting primitive algorithm is conservative to the order of approximation. One dimensional Euler calculations of flows containing strong shocks clearly show that conservation errors in primitive flow calculations are of comparable quality.

Karni, S.

1990-01-01

302

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

NASA Technical Reports Server (NTRS)

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.

Brown, W Byron; Bradshaw, Guy R

1949-01-01

303

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

NASA Astrophysics Data System (ADS)

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.

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

2012-02-01

304

Turbulent flow in a baffled vessel stirred by a 60° pitched blade impeller  

Microsoft Academic Search

The power characteristics of an impeller with six blades, each at 60° to the direction of rotation, in a fully baffled vessel have been quantified as a function of Reynolds number and the mean and turbulent-flow characteristics measured for Reynolds and power numbers of 48,000 and 2.25, respectively. The power number decreased rapidly by 12% at a Reynolds number of

R. M. Hockey; J. M. Nouri

1996-01-01

305

Turbulent flow in stirred vessels agitated by a single, low-clearance hyperboloid impeller  

Microsoft Academic Search

Detailed angle-resolved measurements of the mean and rms of the three components of the velocity vector were carried out by laser-Doppler anemometry in a stirred vessel mechanically agitated by a ribbed, low power consumption hyperboloid impeller at a Reynolds number of 50,000. Due to the small clearance of the agitator the flow pattern in the vessel was typical of that

F. T Pinho; F. M Piqueiro; M. F Proença; A. M Santos

2000-01-01

306

Rotordynamics of Impeller Eye Seals with Wear-Damaged Teeth in Centrifugal Compressors  

Microsoft Academic Search

This paper investigates the influence of labyrinth seal teeth wear damage on the performance and the rotordynamic characteristics of impeller eye seals in centrifugal compressors. A well-established CFD-perturbation model was employed to predict the seal rotordynamic coefficients. The inclusion of at least an approximate shroud leakage path chamber is preferred for an accurate prediction of seal-inlet swirl velocity and flow-induced

JINXIANG XI; DAVID L. RHODE

2006-01-01

307

Turbulent #ow in stirred vessels agitated by a single, low-clearance hyperboloid impeller  

Microsoft Academic Search

Detailed angle-resolved measurements of the mean and rms of the three components of the velocity vector were carried out by laser-Doppler anemometry in a stirred vessel mechanically agitated by a ribbed, low power consumption hyperboloid impeller at a Reynolds number of 50,000. Due to the small clearance of the agitator the #ow pattern in the vessel was typical of that

F. T. Pinho; F. M. Piqueiro; M. F. Proenc; A. M. Santos

2000-01-01

308

Third-generation blood pumps with mechanical noncontact magnetic bearings.  

PubMed

This article reviews third-generation blood pumps, focusing on the magnetic-levitation (maglev) system. The maglev system can be categorized into three types: (i) external motor-driven system, (ii) direct-drive motor-driven system, and (iii) self-bearing or bearingless motor system. In the external motor-driven system, Terumo (Ann Arbor, MI, U.S.A.) DuraHeart is an example where the impeller is levitated in the axial or z-direction. The disadvantage of this system is the mechanical wear in the mechanical bearings of the external motor. In the second system, the impeller is made into the rotor of the motor, and the magnetic flux, through the external stator, rotates the impeller, while the impeller levitation is maintained through another electromagnetic system. The Berlin Heart (Berlin, Germany) INCOR is the best example of this principle where one-axis control combination with hydrodynamic force achieves high performance. In the third system, the stator core is shared by the levitation and drive coil to make it as if the bearing does not exist. Levitronix CentriMag (Zürich, Switzerland), which appeared recently, employs this concept to achieve stable and safe operation of the extracorporeal system that can last for a duration of 14 days. Experimental systems including HeartMate III (Thoratec, Woburn, MA, U.S.A.), HeartQuest (WorldHeart, Ottawa, ON, Canada), MagneVAD (Gold Medical Technologies, Valhalla, NY, U.S.A.), MiTiHeart (MiTi Heart, Albany, NY, U.S.A.), Ibaraki University's Heart (Hitachi, Japan) and Tokyo Medical and Dental University/Tokyo Institute of Technology's disposable and implantable maglev blood pumps are also reviewed. In reference to second-generation blood pumps, such as the Jarvik 2000 (Jarvik Heart, New York, NY, U.S.A.), which is showing remarkable achievement, a question is raised whether a complicated system such as the maglev system is really needed. We should pay careful attention to future clinical outcomes of the ongoing clinical trials of the second-generation devices before making any further remarks. What is best for patients is the best for everyone. We should not waste any efforts unless they are actually needed to improve the quality of life of heart-failure patients. PMID:16683949

Hoshi, Hideo; Shinshi, Tadahiko; Takatani, Setsuo

2006-05-01

309

Measurement of rheology of distiller's grain slurries using a helical impeller viscometer.  

PubMed

Current research is focused on developing a process to convert the cellulose and hemicellulose in distiller's grains into fermentable sugars, increasing both ethanol yield and the amount of protein in the remaining solid product. The rheologic properties of distiller's grain slurries were determined for concentrations of 21, 23, and 25%. Distiller's grain slurries are non-Newtonian, heterogeneous fluids subject to particle settling. Traditional methods of viscosity measurement, such as cone-and-plate and concentric cylinder viscometers, are not adequate for these fluids. A helical impeller viscometer was employed to measure impeller torque over a range of rotational speeds. Newtonian and non-Newtonian calibration fluids were utilized to obtain constants that relate shear stresses and shear rates to the experimental data. The Newtonian impeller constant, c, was 151; the non-Newtonian shear rate constant, k, was 10.30. Regression analysis of experimental data was utilized for comparison to power law, Herschel-Bulkley, and Casson viscosity models with regression coefficients exceeding 0.99 in all cases. PMID:15054288

Houchin, Tiffany L; Hanley, Thomas R

2004-01-01

310

Over the shaft fuel pumping system  

SciTech Connect

This patent describes a gas turbine engine apparatus. It comprises: a compressor adapted to compress air inducted into the engine; a combustor adapted to receive and burn a mixture of fuel and compressed air to produce motive gas, a metering valve adapted to receive fuel and deliver the fuel to the combustor; a turbine adapted to receive the motive gas and produce rotary motion in response thereto; a shaft connected to the turbine and the compressor for transmitting the rotary motion to the compressor; and a vortex pump having an impeller girdling the shaft intermediate the compressor and the turbine rotating therewith, a pump inlet adjacent the shaft in fluid communication with a source of the fuel, a pump outlet in fluid communication with the metering valve, and means for defining a flow path between the fuel source and the inlet whereby the fuel is directed into the inlet in an axial direction which is substantially parallel to the shaft while preventing substantial fuel contact with the shaft so that circumferential fuel swirl at the inlet is minimized.

Hoopes, J.N.; Eick, C.D.; Williamson, J.R.

1991-02-05

311

Pumping Myocytes  

NSDL National Science Digital Library

We may not immediately think of our heart as a collection of individual cells. But it is the complex interaction of numerous cell types that give the heart its ability to pump blood. On this site, you will learn about the cells of the heart and you will get a see a video of the cells within the heart.

2010-01-01

312

Dilepton production in schematic causal viscous hydrodynamics  

NASA Astrophysics Data System (ADS)

Assuming that in the hot dense matter produced in relativistic heavy-ion collisions, the energy density, entropy density, and pressure as well as the azimuthal and space-time rapidity components of the shear tensor are uniform in the direction transversal to the reaction plane, we derive a set of schematic equations from the Isreal-Stewart causal viscous hydrodynamics. These equations are then used to describe the evolution dynamics of relativistic heavy-ion collisions by taking the shear viscosity to entropy density ratio of 1/4? for the initial quark-gluon plasma (QGP) phase and of 10 times this value for the later hadron-gas (HG) phase. Using the production rate evaluated with particle distributions that take into account the viscous effect, we study dilepton production in central heavy-ion collisions. Compared with results from the ideal hydrodynamics, we find that although the dilepton invariant mass spectra from the two approaches are similar, the transverse momentum spectra are significantly enhanced at high transverse momenta by the viscous effect. We also study the transverse momentum dependence of dileptons produced from QGP for a fixed transverse mass, which is essentially absent in the ideal hydrodynamics, and find that this so-called transverse mass scaling is violated in the viscous hydrodynamics, particularly at high transverse momenta.

Song, Taesoo; Han, Kyong Chol; Ko, Che Ming

2011-02-01

313

Dilepton production in schematic causal viscous hydrodynamics  

E-print Network

to entropy density ratio of 1/4 pi for the initial quark-gluon plasma (QGP) phase and of 10 times this value for the later hadron-gas (HG) phase. Using the production rate evaluated with particle distributions that take into account the viscous effect, we...

Song, Taesoo; Han, Kyong Chol; Ko, Che Ming.

2011-01-01

314

Whirling cable subjected to viscous drag  

Microsoft Academic Search

The equilibrium configuration and stability of a linearly elastic whirling cable with an attached spherical drogue are analyzed using the finite element method. A simple viscous drag law is used, where fluid drag is assumed to be proportional to the cable velocity but directed in an opposite sense. The problem includes strong geometrical nonlinearities which result in both static and

J. J. Russell; W. J. Anderson

1974-01-01

315

Injection Well Logging Using Viscous EOR Fluids  

Microsoft Academic Search

A new tool has been developed that overcomes problems associated with logging injection wells in the presence of viscous fluids. The tool was evaluated in the laboratory and the field in water and polymer injection wells. Results indicate that the tool provides better information than conventional equipment. Special attention to log interpretation is required in zones where the flow pattern

Bruce Knight; Mohammad Davarzani

1986-01-01

316

Visualization of viscous fingering in chromatographic columns  

Microsoft Academic Search

A 17 mm I.D. glass column, packed with YMC-15 (spherical C18 silica, 30 ?m particles) as the stationary phase and used with carbon tetrachloride as the mobile phase provided a suitable system for the visual observation of viscous fingering inside the packed bed, after the cylindrical lens effect had been canceled. Such a system appears nearly transparent due to the

B. Scott Broyles; R. Andrew Shalliker; Djamel E Cherrak; Georges Guiochon

1998-01-01

317

OPTIMAL CHATTERING CONTROLS FOR VISCOUS FLOW  

E-print Network

additive probability mea­ sures defined on the control set. Another main result is an approxi­ mation control theory of viscous flow has many important applications in engineering science. During the past few years several fundamental advances have been reported for flow control problems with convex cost. Main

318

Lepton pair production from viscous QGP  

NASA Astrophysics Data System (ADS)

In Israel-Stewart’s second order hydrodynamics, the viscous effect of dilepton emission from a QGP medium is investigated. Dileptons are strongly affected by QGP viscosity. Large invariant mass dileptons, due to their lower velocity, are less affected by viscosity than the low invariant mass dileptons.

Chaudhuri, A. K.; Sinha, Bikash

2013-04-01

319

Viscous Driven-Cavity Solver: User's Manual  

NASA Technical Reports Server (NTRS)

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.

Wood, William A.

1997-01-01

320

Numerical study of impeller-driven von Kármán flows via a volume penalization method  

NASA Astrophysics Data System (ADS)

Studying strongly turbulent flows is still a major challenge in fluid dynamics. It is highly desirable to have comparable experiments to obtain a better understanding of the mechanisms generating turbulence. The von Kármán flow apparatus is one of those experiments that has been used in various turbulence studies by different experimental groups over the last two decades. The von Kármán flow apparatus produces a highly turbulent flow inside a cylinder vessel driven by two counter-rotating impellers. The studies cover a broad range of physical systems including incompressible flows, especially water and air, magnetohydrodynamic systems using liquid metal for understanding the important topic of the dynamo instability, particle tracking to study Lagrangian type turbulence and recently quantum turbulence in super-fluid helium. Therefore, accompanying numerical studies of the von Kármán flow that compare quantitatively data with those from experiments are of high importance for understanding the mechanism producing the characteristic flow patterns. We present a direct numerical simulation (DNS) version the von Kármán flow, forced by two rotating impellers. The cylinder geometry and the rotating objects are modelled via a penalization method and implemented in a massive parallel pseudo-spectral Navier–Stokes solver. From the wide range of different impellers used in von Kármán water and sodium experiments we choose a special configuration (TM28), in order to compare our simulations with the according set of well documented water experiments. Though this configuration is different from the one in the final VKS experiment (TM73), using our method it is quite easy to change the impeller shape to the one actually used in VKS. The decomposition into poloidal and toroidal components and the mean velocity field from our simulations are in good agreement with experimental results. In addition, we analysed the flow structure close to the impeller blades, a region hardly accessible to experiments. Depending on the blade geometry different vortex topologies are found. The very promising results imply that our numerical modelling could also be applied to other physical systems and configurations driven by the von Kármán flow.

Kreuzahler, S.; Schulz, D.; Homann, H.; Ponty, Y.; Grauer, R.

2014-10-01

321

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

PubMed

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

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

322

Gap velocity measurements of a blood pump model.  

PubMed

This paper presents the velocity measurements in the gap between the impeller and the pump casing of a 5:1 enlarged centrifugal blood pump model at operating condition. Both the radial and tangential velocity at the gap were measured. It was found that there was no cross flow in both the radial and tangential velocity distributions at the seven radial locations. This implies that the 0.2 mm gap in the prototype should be the optimal clearance of the pump. The vector plot of the resultant velocity showed that the double volute design of the pump, especially the splitter plate that started at theta; = 180 degrees, has created a washout mechanism in the clearance gap; that is, a sector of flow ranging from theta; = 100 degrees to theta; = 190 degrees has directed strongly toward the eye while the rest of the flow in the gap is in a tangential direction. It is important that the blood should flow out of the gap through the eye instead of continuing to circulate in the clearance gap. This explains why the pump has minimum hemolysis and thrombus formation and is able to function with nominal efficiency as compared to other centrifugal pumps. PMID:12139495

Chua, Leok Poh; Ong, Kang Shiu; Yu, Ching Man Simon; Chan, Weng Kong; Wong, Yew Wah

2002-08-01

323

Suppression of the secondary flow in a suction channel of a large centrifugal pump  

NASA Astrophysics Data System (ADS)

The suction channel configuration of a large centrifugal pump with a 90-degree bend was studied in detail to suppress the secondary flow at the impeller inlet for improving suction performance. Design of experiments (DOE) and computational fluid dynamics (CFD) were used to evaluate the sensitivity of several primary design parameters of the suction channel. A DOE is a powerful tool to clarify the sensitivity of objective functions to design parameters with a minimum of trials. An L9 orthogonal array was adopted in this study and nine suction channels were designed, through which the flow was predicted by steady state calculation. The results indicate that a smaller bend radius with a longer straight nozzle, distributed between the bend and the impeller, suppresses the secondary flow at the impeller inlet. An optimum ratio of the cross sectional areas at the bend inlet and outlet was also confirmed in relationship to the contraction rate of the downstream straight nozzle. These findings were obtained by CFD and verified by experiments. The results will aid the design of large centrifugal pumps with better suction performance and higher reliability.

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

2013-12-01

324

Three-dimensional numerical prediction of stress loading of blood particles in a centrifugal pump.  

PubMed

The successful use of centrifugal pumps as temporary cardiac assist devices strongly depends on their degree of blood trauma. The mechanical stress loading experienced by cellular components on their passage through the pump is a major cause of blood trauma. Prediction of the mechanical stresses will assist optimization of pump design to minimize hemolysis and platelet activation. As a theoretical approach to this task., the determination of the complete three-dimensional (3D) flow field including all regions of high shear stress is therefore required. A computational fluid dynamics (CFD) software package, TASCflow, was used to model flow within a commercially available pump, the Aries Medical Isoflow Pump. This pump was selected in order to demonstrate the ability of the CFD software to handle complex impeller geometries. A turbulence model was included, and the Newtonian as well as the Reynolds stress tensor calculated for each nodal point. A novel aspect was the assignment of scalar stress values to streaklines representing particle paths through the pump. Scalar stress values were obtained by formulating a theory that enables the comparison of a three-dimensional state of stress with a uniaxial stress as applied in all mechanical blood damage tests. Stress loading-time functions for fluid particles passing inlet, impeller, and outlet domains of the pump were obtained. These showed that particles undergo a complex, irregularly fluctuating stress loading. Future blood damage theories would have to consider an unsteady stress loading regime that realistically reflects the flow conditions occurring within the pump.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:8572957

Bludszuweit, C

1995-07-01

325

Dependence of penicillium chrysogenum growth, morphology, vacuolation, and productivity in fed-batch fermentations on impeller type and agitation intensity  

PubMed

The influence of the agitation conditions on the growth, morphology, vacuolation, and productivity of Penicillium chrysogenum has been examined in 6 L fed-batch fermentations. A standard Rushton turbine, a four-bladed paddle, and a six-bladed pitched blade impeller were compared. Power inputs per unit volume of liquid, P/VL, ranged from 0.35 to 7.4 kW/m3. The same fermentation protocol was used in each fermentation, including holding the dissolved oxygen concentration above 40% air saturation by gas blending. The mean projected area (for all dispersed types, including clumps) and the clump roughness were used to characterize the morphology. Consideration of clumps was vital as these were the predominant morphological form. For a given impeller, the batch-phase specific growth rates and the overall biomass concentrations increased with agitation intensity. Higher fragmentation at higher speeds was assumed to have promoted growth through increased formation of new growing tips. The mean projected area increased during the rapid growth phase followed by a sharp decrease to a relatively constant value dependent on the agitation conditions. The higher the speed, the lower the projected area for a given impeller type. The proportion by volume of hyphal vacuoles and empty regions decreased with speed, possibly due to fragmentation in the vacuolated regions. The specific penicillin production rate was generally higher with lower impeller speed for a given impeller type. The highest value of penicillin production as well as its rate was obtained using the Rushton turbine impeller at the lowest speed. At given P/VL, changes in morphology, specific growth rate, and specific penicillin production rate depended on impeller geometry. The morphological data could be correlated with either tip speed or the "energy dissipation/circulation function," but a reasonable correlation of the specific growth rate and specific production rate was only possible with the latter. Copyright 1998 John Wiley & Sons, Inc. PMID:10099397

J sten P; Paul; Nienow; Thomas

1998-09-20

326

Computational Approach for Developing Blood Pump  

NASA Technical Reports Server (NTRS)

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

Kwak, Dochan

2002-01-01

327

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

NASA Astrophysics Data System (ADS)

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.

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

2012-11-01

328

Designing an Optimal DC Electrokinetic Pump  

NASA Astrophysics Data System (ADS)

A sol-gel process is used to fabricate a medium for DC electrokinetic pumps such that its micron-sized through pore is comparable in dimension to the surface double layer thickness of weak electrolytes and organic solvents. Under such conditions, the opposite double layers within the channel do not overlap to reduce the total polarization, as in nanoporous materials, and yet the hydrodynamic shear stress spans the entire channel to relieve the large viscous dissipation associated with electrokinetic flows. The silica matrix is wettable by most solvents and possesses a large surface charge density both necessary features for a good DC pump medium. As there is almost no electro-neutral fluid within the medium, we observed a curios phenomenon associated with this matrix--the DC current through it is due almost entirely to advection current. AS such, the pump can function as a flow sensor and a constant flow rate can be maintained against a varying load by controlling the current. The maximum flow rate and maximum pressure generated by the pump housed in a 100-micron capillary are 2 microL/min and 0.4 MPa , respectively, at 6 kV. We have measured the pressure curves of this pump for a variety of solvents and ion concentrations to verify the optimality of the pump and the dominance of advection current.

Wang, Ping; Chen, Zilin; Chang, Hsueh-Chia

2004-11-01

329

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

NASA Technical Reports Server (NTRS)

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.

Ware, Marsden; Wilson, Ernest E

1929-01-01

330

Viscous damping of perforated planar micromechanical structures  

PubMed Central

The paper gives an analytical approximation to the viscous damping coefficient due to the motion of a gas between a pair of closely spaced fluctuating plates in which one of the plates contains a regular system of circular holes. These types of structures are important parts of many microelectromechanical devices realized in MEMS technology as microphones, microaccelerometers, resonators, etc. The pressure satisfies a Reynolds’ type equation with coefficients accounting for all the important effects: compressibility of the gas, inertia and possibly slip of the gas on the plates. An analytical expression for the optimum number of circular holes which assure a minimum value of the total damping coefficient is given. This value realizes an equilibrium between the squeeze-film damping and the viscous resistance of the holes. The paper also provides analytical design formulas to be used in the case of regular circular perforated plates. PMID:19365579

Homentcovschi, D.; Miles, R.N.

2008-01-01

331

Thermal radiation from an expanding viscous medium  

E-print Network

The effects of viscosity on the space time evolution of QGP produced in nuclear collisions at RHIC energies have been studied. The entropy generated due to the viscous motion of the fluid has been taken into account in constraining the initial temperature by the final multiplicity (measured at the freeze-out point). The viscous effects on the photon spectra has been introduced consistently through the evolution dynamics and phase space factors of the particles participating in the production process. We notice a stronger effect on the photon spectra originating from QGP than hadronic matter. A detectable shift is observed in the space-time integrated p_T distribution of photons due to dissipative effects.

Sukanya Mitra; Payal Mohanty; Sourav Sarkar; Jan-e Alam

2011-07-13

332

Numerical simulation of the effect of solid-volume fraction on induction force of screw centrifugal pump  

NASA Astrophysics Data System (ADS)

The solid-liquid two-phase unsteady flow in a screw centrifugal pump was simulated with unsteady Reynolds averaged Navier-Stokes equations and sliding mesh technology. The distribution of the pressure at volute outlet, radial force, axial force and total moment are presented in this paper. The effects of solid-phase volume fractions on the value and direction of the induction thrust are analyzed. Seven monitor points are arranged on the inner surface of volute along the impeller rotation. The characters of the induced force on the monitor points with different solid-phase volume fractions are investigated. The results indicated that different solid-volume fractions have litter effects on the trend and direction of pressure at volute, radial force, axial force and total moment during one period, but the value of induction forces increase with the increasing of solid-volume fraction; The pressure fluctuation on the monitor points has with different trends during one period, which depends on the direction of the monitor points and the rotor-stator interaction strength of impeller and volute. With the rotation of impeller, the values of pressure in the whole passage are further increased along the rotation direction with the role of impeller vane. Solid-phase volume fraction has few effects on change trend of induced thrust as radial force and axial force on the monitor points, but the values of pressure on the monitor points increase with the increasing of solid-volume fraction.

Han, W.; Ma, W.; Li, R. N.; Gao, Y.; Gao, H.

2012-11-01

333

Viscous Overstability in Saturn's B Ring  

Microsoft Academic Search

Local simulations with up to 60,000 self-gravitating dissipatively colliding particles indicate that dense unperturbed ring systems with optical depth ?>1 can exhibit spontaneous viscous oscillatory instability (overstability), with parameter values appropriate for Saturn's B ring. These axisymmetric oscillations, with scale ?100 m and frequency close to the orbital period, generally coexist with inclined Julian–Toomre type wakes forming in gravitating disks.

Heikki Salo; Jürgen Schmidt; Frank Spahn

2001-01-01

334

Galloping instability of viscous shock waves  

Microsoft Academic Search

Motivated by physical and numerical observations of time oscillatory ``galloping'', ``spinning'', and ``cellular'' instabilities of detonation waves, we study Poincar\\\\'e--Hopf bifurcation of traveling-wave solutions of viscous conservation laws. The main difficulty is the absence of a spectral gap between oscillatory modes and essential spectrum, preventing standard reduction to a finite-dimensional center manifold. We overcome this by direct Lyapunov--Schmidt reduction, using

Benjamin Texier; Kevin Zumbrun

2006-01-01

335

Low thrust viscous nozzle flow fields prediction  

NASA Technical Reports Server (NTRS)

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.

Liaw, G. S.; Mo, J. D.

1991-01-01

336

Numerical Simulation of Viscous Accretion Disks  

NASA Astrophysics Data System (ADS)

A two-and three-dimensional numerical hydrodynamics FORTRAN code is developed to model viscous accretion disks, employing the method of smoothed particle hydrodynamics. The effective shear viscosity present in the code is evaluated. Using a polytropic equation of state, models of self-gravitating accretion disks are evolved with central mass to disk ratios of 1 and 3, with ratios of specific heats of 2 and 5/3, and with an artificial viscosity parameter of 1, 0.5, 0.25. From these models it is found that a characteristic mass accretion rate, constant with time, is maintained by the accretion disks, and that mass accretion is inversely proportional to the strength of the local shear viscous force. This is a consequence of the effect of local viscous forces upon the global non-axisymmetric modes that primarily drive accretion in these disks. In addition, the formation of satellites is observed in models which also develop a dominating m = 1 mode. The relevance of these satellites to planet formation is speculated.

Drimmel, Ronald Eugene

1995-01-01

337

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)

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.

Beede, William L.; Kovach, Karl

1948-01-01

338

Determining the parameters of the flow in impellers of centrifugal refrigeration compressors  

SciTech Connect

The authors examine a method of calculating the flow past the impeller lattice (IL) of refrigerating compressors with allowance for the real thermodynamic properties of the refrigerants and the variation in the density in the interblade channels. The familiar solution of the problem of the flow past a lattice by the method of characteristic features was supplemented by computation of the compression process in the IL channels using the equation of state of a real refrigerant. The problem was solved using an ES computer.

Golovin, M.V.; Nuzhdin, A.S.; Sukhomlinov, I.Y.

1986-09-01

339

Optimization of residual heat removal pump axial thrust and axial bearing  

SciTech Connect

The residual heat removal (RHR) pumps of German 1300 megawatt pressurized-water reactor (PWR) power plants are of the single stage end suction type with volute casing or with diffuser and forged circular casing. Due to the service conditions the pumps have to cover the full capacity range as well as a big variation in suction static pressure. This results in a big difference in the axial thrust that has to be borne by the axial bearing. Because these pumps are designed to operate without auxiliary systems (things that do not exist can not fail), they are equipped with antifriction bearings and sump oil lubrication. To minimize the heat production within the bearing casing, a number of PWR plants have pumps with combined axial/radial bearings of the ball type. Due to the fact that the maximum axial thrust caused by static pressure and hydrodynamic forces on the impeller is too big to be borne by that type of axial bearing, the impellers were designed to produce a hydrodynamic axial force that counteracts the static axial force. Thus, the resulting axial thrust may change direction when the static pressure varies.

Schubert, F.

1996-12-01

340

Improvement of hemocompatibility for hydrodynamic levitation centrifugal pump by optimizing step bearings.  

PubMed

We have developed a hydrodynamic levitation centrifugal blood pump with a semi-open impeller for a mechanically circulatory assist. The impeller levitated with original hydrodynamic bearings without any complicated control and sensors. However, narrow bearing gap has the potential for causing hemolysis. The purpose of the study is to investigate the geometric configuration of the hydrodynamic step bearing to minimize hemolysis by expansion of the bearing gap. Firstly, we performed the numerical analysis of the step bearing based on Reynolds equation, and measured the actual hydrodynamic force of the step bearing. Secondly, the bearing gap measurement test and the hemolysis test were performed to the blood pumps, whose step length were 0 %, 33 % and 67 % of the vane length respectively. As a result, in the numerical analysis, the hydrodynamic force was the largest, when the step bearing was around 70 %. In the actual evaluation tests, the blood pump having step 67 % obtained the maximum bearing gap, and was able to improve the hemolysis, compared to those having step 0% and 33%. We confirmed that the numerical analysis of the step bearing worked effectively, and the blood pump having step 67 % was suitable configuration to minimize hemolysis, because it realized the largest bearing gap. PMID:22254562

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

2011-01-01

341

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

SciTech Connect

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.

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

1993-07-01

342

Secondary flow, separation and losses in the NACA 48-inch centrifugal impeller at design and off-design conditions  

NASA Astrophysics Data System (ADS)

An elliptic flow calculation procedure has been used to model three-dimensional flow in the NACA 48-inch centrifugal impeller. The results demonstrate that fully elliptic steady flow calculations can be performed at design and off-design conditions. The calculations reproduce the measured overall performance and most of the features of the loss distributions observed in the NACA flow study. They give further insight into the complex three-dimensional flow with leading-edge separation and tip leakage. The calculated secondary flow patterns are presented and used to explain the convection of vortices in a more recent laser anemometry study of a centrifugal compressor impeller.

Moore, John; Moore, Joan G.

1988-06-01

343

Evaluation of Failed Crane Chempumps Used During Salt Well Pumping  

SciTech Connect

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.

ELSEN, J.J.

2000-09-18

344

Numerical simulation for a centrifugal heart pump  

NASA Astrophysics Data System (ADS)

The primary focus of this work is to investigate unsteady flow simulations for an incompressible fluid. Computational codes are developed and applied for the purpose of analyzing the flow in a centrifugal heart pump, the Innovative Ventricular Assist System (IVAS) pump, which was developed by the Cleveland Clinic Foundation as a part of the National Institute of Health's artificial heart program. In order to simulate the complex flow in the IVAS pump, three capabilities must be incorporated into the simulation codes. The first capability is that the code must be able to simulate the flow through an IVAS pump for Reynolds numbers 30,000~80,000 with numerical stability. The Reynolds numbers in this range are considered to be high in incompressible flow and to have difficulty in simulating a flow with numerical stability. The second capability is that the codes must solve 2-1/2 dimensional Navier-Stokes equations. The 2-1/2 dimensional Navier- Stokes equations are written in such a way that the effect of the variable thickness is included in two- dimensions. The 2-1/2 dimensional analysis enables the simulation of the flow, including the various thickness effects, at nearly the computational speed of two- dimensional analysis. The third capability is that the code must simulate the flow for the entire centrifugal pump, which includes an inlet, rotating blades, a volute, and a diffuser. To perform this intensive calculation, parallel computing is used because of its high computing speed and its ability to accommodate the large computational domain by task partitioning. An intensive parametric study using a single-processor computer is performed with a view to identifying certain problematic aspects of the design methodology. According to the present analysis, the effects of a Reynolds number based on the blade radius and its velocity are not significant for typical pump operation conditions. The flow characteristics, however, change with the Reynolds numbers when they are low. In general, the pressure rise across the pump impeller increases as the radius of the blade arc increases and as the number of blades increases. The findings of this study qualitatively agree with the Euler turbine equation with respect to the effects of the leading edge (inflow) angle and the trailing edge (outflow) angle.

Yano, Keiji

345

Evaluation of static mixer flow enhancements for cryogenic viscous compressor prototype for ITER vacuum system  

NASA Astrophysics Data System (ADS)

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.

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

346

Evaluation of Static Mixer Flow Enhancements for Cryogenic Viscous Compressor Prototype for ITER Vacuum System  

SciTech Connect

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

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

347

Melt agglomeration with polyethylene glycol beads at a low impeller speed in a high shear mixer.  

PubMed

This study was performed in order to evaluate the possibility of obtaining spherical agglomerates with a high content of meltable binder by a melt agglomeration process in a high shear mixer. Lactose monohydrate was melt agglomerated with polyethylene glycol (PEG) 1500 or 6000 in a 10-l high shear mixer at an impeller speed of 400 rpm. The PEG 1500 was used as a size fraction of beads, and the PEG 6000 as a fine powder, a powder, unfractionated beads, and size fractions of beads. It was found to be possible to incorporate a high amount of PEG (28% m/m of the amount of lactose), because the rather low impeller speed applied in the present experiments caused less densification of the agglomerates. The fine powder of the PEG 6000 caused a complete adhesion of the mass to the bowl shortly after melting. A rapid agglomerate growth by coalescence was found to be the dominant growth mechanism when agglomeration was performed with the PEG 6000 powder. The PEG beads resulted in a slow and more controllable agglomerate growth, because the growth occurred primarily by an immersion of the lactose particles in the surface of the molten binder droplets. The initial shape of the agglomerates produced with the PEG beads was similar to the spherical shape of the beads. This shape could not be maintained during the process due to a breakage of the agglomerates caused by a hollow structure of the PEG beads. PMID:11677074

Seo, A; Schaefer, T

2001-11-01

348

Tensile and Creep Property Characterization of Potential Brayton Cycle Impeller and Duct Materials  

NASA Technical Reports Server (NTRS)

This paper represents a status report documenting the work on creep of superalloys performed under Project Prometheus. 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, are being screened to compare their respective capabilities for impeller applications. Several wrought superalloys including Hastelloy X, (Haynes International, Inc., Kokomo, IN), Inconel 617, Inconel 740, Nimonic 263, and Incoloy MA956 (Special Metals Corporation, Huntington, WV) are also being screened to compare their capabilities for duct applications. 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. Conventional tensile and creep tests were performed at temperatures up to 1200 K on specimens extracted from the materials. Initial microstructure evaluations were also undertaken.

Gabb, Timothy P.; Gayda, John

2006-01-01

349

Scale-up of biotransformation process in stirred tank reactor using dual impeller bioreactor.  

PubMed

The gas-liquid mass transfer coefficient K(L)a in the fermenter is a strong function of mode of energy dissipation and physico-chemical properties of the liquid media. A combination of disc turbine (DT) and pitched blade turbine down flow (PTD) impellers has been tested in laboratory bioreactor for gas hold-up and gas-liquid mass transfer performance for the growth and biotransformation medium for an yeast isolate VS1 capable of biotransforming benzaldehyde to L-phenyl acetyl carbinol (L-PAC) and compared with those in water.Correlations have been developed for the prediction of the fractional gas hold-up and gas-liquid mass transfer coefficient for the above media. The mass transfer coefficient and respiration rate have been determined in the shake flask for the growth as well as for biotransformation medium. These results, then have been used to optimize the operating parameters (impeller speed and aeration) for growth and biotransformation in a laboratory bioreactor. The comparison of cell mass production and L-PAC production in the bioreactor has been done with that obtained in shake flask studies. PMID:11356367

Shukla, V B.; Parasu Veera, U; Kulkarni, P R.; Pandit, A B.

2001-07-01

350

Orthogonal decomposition as a design tool: With application to a mixing impeller  

SciTech Connect

Digital manufacturing eliminates the expense and time required to develop custom products. By utilizing this technology, designers can quickly create a customized product specifically for their performance needs. But the timescale and expense from the engineering design workflows used to develop these customized products have not been adapted from the workflows used in mass production. In many cases these customized designs build upon already successful mass-produced products that were developed using conventional engineering design workflows. Many times as part of this conventional design process significant time is spent creating and validating high fidelity models that accurately predict the performance of the final design. These existing validated high fidelity models used for the mass-produced design can be reused for analysis and design of unknown products. This thesis explores the integration of reduced order modeling and detailed analysis into the engineering design workflow developing a customized design using digital manufacturing. Specifically, detailed analysis is coupled with proper orthogonal decomposition to enable the exploration of the design space while simultaneously shaping the model representing the design. This revised workflow is examined using the design of a laboratory scale overhead mixer impeller. The case study presented here is compared with the design of the Kar Dynamic Mixer impeller developed by The Dow Chemical Company. The result of which is a customized design for a refined set of operating conditions with improved performance.

Sloan, Benjamin

2013-05-15

351

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

USGS Publications Warehouse

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.

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

2005-01-01

352

Creep Property Characterization of Potential Brayton Cycle Impeller and Duct Materials  

NASA Technical Reports Server (NTRS)

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(Registered TradeMark) X, Inconel(Registered TradeMark) 617, Inconel(Registered TradeMark) 740, Nimonic(Registered TradeMark) 263, Incoloy(Registered TradeMark) 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.

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

2007-01-01

353

MOLTEN PLUTONIUM PUMP EXPERIMENT  

Microsoft Academic Search

The Molten Plutonium Pump Experiment was a subcritical mock-up of a ; reactor core in which a plutonium-iron alloy was circulated by means of a sodium ; lift pump. Sodium for the lift pumping was circulated by an E. M. pump in an ; isothermal loop at 500 deg C. The purpose of the test was to study pump ;

J. E. Deverall; G. L. Caldwell

1962-01-01

354

Development of a magnetically suspended centrifugal pump as a cardiac assist device for long-term application.  

PubMed

To overcome problems with the shaft seal in conventional centrifugal pumps, the authors have been developing a magnetically suspended centrifugal pump (MSCP) that operates as a valveless, sealless, and bearingless pump. The prototype of the MSCP was modified with respect to size of the volute diffuser and impeller blade profiles. A hemolysis test in vitro using a new version of the MSCP was performed in comparison with a commercially available centrifugal pump. The test circuit for the hemolysis test comprised a blood reservoir, a pump, and polyvinyl tubes, and was filled with fresh heparinized bovine blood. The pumping conditions were a flow rate of 5 L/min and a pump head afterload of 100 mmHg. The index of hemolysis in the MSCP was significantly lower than that in the Biomedicus pump (0.0035 +/- 0.0025 versus 0.0097 +/- 0.0056 g/100 L, p < 0.05). Reduction in the platelet count during pumping also was lower in the MSCP compared with the Biomedicus pump at both 6 hrs and 12 hrs of pumping (p < 0.01). This MSCP may be advantageous for extended use of assist devices, not only from the theoretical point of view, but in a practical sense after the results of the current hemolysis test. PMID:8808462

Nishimura, K; Park, C H; Akamatsu, T; Yamada, T; Ban, T

1996-01-01

355

Effect of impeller type and agitation on the performance of pilot scale ASBR and AnSBBR applied to sanitary wastewater treatment.  

PubMed

The objective of this work was to assess the effect of agitation rate and impeller type in two mechanically stirred sequencing batch reactors: one containing granulated biomass (denominated ASBR) and the other immobilized biomass on polyurethane foam (denominated AnSBBR). Each configuration, with total volume of 1 m(3), treated 0.65 m(3) sanitary wastewater at ambient temperature in 8-h cycles. Three impeller types were assessed for each reactor configuration: flat-blade turbine impeller, 45 degrees -inclined-blade turbine impeller and helix impeller, as well as two agitation rates: 40 and 80 rpm, resulting in a combination of six experimental conditions. In addition, the ASBR was also operated at 20 rpm with a flat-blade turbine impeller and the AnSBBR was operated with a draft tube and helix impeller at 80 and 120 rpm. To quantify how impeller type and agitation rate relate to substrate consumption rate, results obtained during monitoring at the end of the cycle, as well as the time profiles during a cycle were analyzed. Increasing agitation rate from 40 rpm to 80 rpm in the AnSBBR improved substrate consumption rate whereas in the ASBR this increase destabilized the system, likely due to granule rupture caused by the higher agitation. The AnSBBR showed highest solids and substrate removal, highest kinetic constant and highest alkalinity production when using a helix impeller, 80 rpm, and no draft tube. The best condition for the ASBR was achieved with a flat-blade turbine impeller at 20 rpm. The presence of the draft tube in the AnSBBR did not show significant improvement in reactor efficiency. Furthermore, power consumption studies in these pilot scale reactors showed that power transfer required to improve mass transfer might be technically and economically feasible. PMID:20363066

de Novaes, Luciano Farias; Saratt, Bruna Luckmann; Rodrigues, José Alberto Domingues; Ratusznei, Suzana Maria; de Moraes, Deovaldo; Ribeiro, Rogers; Zaiat, Marcelo; Foresti, Eugenio

2010-08-01

356

Viscous dark energy and generalized second law of thermodynamics  

E-print Network

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.

M. R. Setare; A. Sheykhi

2011-03-05

357

Injection pump  

SciTech Connect

An injection pump includes a rotor having a central axial bore and a radial bore and rotated in relationship with an engine. A free piston reciprocably inserted in the central axial bore defines a first and second chamber. The first chamber includes a plurality of first radial passages and a radial spill port and communicate with the radial bore and the second pressure chamber includes a plurality of second radial passages and a discharge passage. A pair of plungers which is disposed in the radial bore is so constructed as to produce, in accordance with the revolution of the rotor, a compression period in which the liquid fuel is pressurized in the first pressure chamber and pressurized fuel in the second pressure chamber is supplied to the engine through the discharge passage, and a suction period in which the liquid fuel is supplied to the pressure chambers.

Hoshi, Y.

1984-05-01

358

A new model of centrifugal blood pump for cardiopulmonary bypass: design improvement, performance, and hemolysis tests.  

PubMed

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

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

359

Waveguide sensor for measurement of viscosity of highly viscous fluids  

NASA Astrophysics Data System (ADS)

Ultrasonic waveguide sensor for measurement of viscosity of highly viscous fluids has been developed. The measurement principle is based on application of guided shear-horizontal SH0 mode of the Lamb waves propagating in an aluminium planar waveguide immersed in a viscous liquid. Attenuation of the guided wave depends on viscosity of the surrounding liquid and is used for viscosity estimation. The developed sensor is mechanically robust and may be used for in-line process control of viscous liquids.

Kazys, R.; Sliteris, R.; Raisutis, R.; Zukauskas, E.; Vladisauskas, A.; Mazeika, L.

2013-11-01

360

Wave Coupling across a Shock Wave in a Viscous Plasma  

Microsoft Academic Search

This paper presents a theory of the coupling between electron-acoustic, ion-acoustic, and electromagnetic plane waves at an idealized shock front in a two-fluid, fully ionized viscous plasma. The viscous-fluid equations and Maxwell's equations are used to derive the dispersion equation relating the frequency and propagation constant of possible modes of propagation in a viscous plasma. Boundary conditions which must hold

Samuel H. Francis; David Kahn

1970-01-01

361

Temperature behaviour of viscous flow with proteins.  

PubMed

The paper presents the results of viscosity determinations on aqueous solutions of different mammalian serum albumins at a wide range of concentrations and at temperatures ranging from 278 K to 318 K. On the basis of these measurements and a modified Arrhenius equation, the functional dependence of the solution activation energy of viscous flow on temperature was established. The analysis of the results obtained shows that the activation energy decreases with increasing temperature according to a square function for solutions, water molecules, and the albumins studied. The rate at which the activation energy decreases with increasing temperature is different for each albumin and mainly depends on its hydrodynamic radius. PMID:21613666

Monkos, Karol

2011-06-01

362

Steady viscous flow past a circular cylinder  

NASA Technical Reports Server (NTRS)

Viscous flow past a circular cylinder becomes unstable around Reynolds number Re = 40. With a numerical technique based on Newton's method and made possible by the use of a supercomputer, steady (but unstable) solutions have been calculated up to Re = 400. It is found that the wake continues to grow in length approximately linearly with Re. However, in conflict with available asymptotic predictions, the width starts to increase very rapidly around Re = 300. All numerical calculations have been performed on the CDC CYBER 205 at the CDC Service Center in Arden Hills, Minnesota.

Fornberg, B.

1984-01-01

363

Multigrid Approach to Incompressible Viscous Cavity Flows  

NASA Technical Reports Server (NTRS)

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.

Wood, William A.

1996-01-01

364

Wall reflection of a viscous vortex ring  

NASA Technical Reports Server (NTRS)

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.

Sa, J. Y.; Chang, K. S.; Liu, C. H.

1986-01-01

365

Viscous damped space structure for reduced jitter  

NASA Technical Reports Server (NTRS)

A technique to provide modal vibration damping in high performance space structures was developed which uses less than one once of incompressible fluid. Up to 50 percent damping can be achieved which can reduce the settling times of the lowest structural mode by as much as 50 to 1. This concept allows the designers to reduce the weight of the structure while improving its dynamic performance. Damping by this technique is purely viscous and has been shown by test to be linear over 5 orders of input magnitude. Amplitudes as low as 0.2 microinch were demonstrated. Damping in the system is independent of stiffness and relatively insensitive to temperature.

Wilson, James F.; Davis, L. Porter

1987-01-01

366

Viscous contributions to the pressure for potential flow analysis of capillary instability of two viscous fluids  

E-print Network

and that of surrounding air on the stability of a columnar jet. The effect of viscosity on the stability of a liquid viscous fluids J. Wang and D. D. Josepha Department of Aerospace Engineering and Mechanics, University; published online 2 May 2005 Capillary instability of a liquid cylinder immersed in another liquid

Joseph, Daniel D.

367

Controls of Wellbore Flow Regimes on Pump Effluent Composition  

SciTech Connect

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.

James Martin-Hayden; plummer; Sanford Britt

2014-01-01

368

Resonantly pumped optical pumping injection cavity lasers  

E-print Network

An optical parametric oscillator is tuned to the resonance wavelength of the etalon in an optical pumping injection cavity (OPIC) laser with a type-II "W" active region, thereby minimizing the threshold pump intensity and ...

Santilli, Michael Robert; McAlpine, T. C.; Greene, K. R.; Olafsen, L. J.; Bewley, W. W.; Felix, C. L.; Vurgaftman, I.; Meyer, J. R.; Lee, H.; Martinelli, R. U.

2004-11-01

369

A pivot bearing-supported centrifugal pump for a long-term assist heart.  

PubMed

A pivot bearing-supported centrifugal blood pump has been developed. It is a compact, cost effective, and anti-thrombogenic pump with anatomical compatibility. A preliminary evaluation of five paracorporeal left ventricular assist studies were performed on pre-conditioned bovine (70-100 kg), without cardiopulmonary bypass and aortic cross-clamping. The inflow cannula was inserted into the left ventricle (LV) through the apex and the outflow cannula affixed with a Dacron vascular graft was anastomosed to the descending aorta. All pumps demonstrated trouble free performance over a two-week screening period. Among these five studies, three implantations were subjected for one month system validation studies. All the devices were trouble free for longer than 1 month. (35, 34, and 31 days). After achieving one month studies, all experiments were terminated. There was no evidence of device induced thrombus formation inside the pump. The plasma free hemoglobin levels were within normal ranges throughout all experiments. As a consequence of these studies, a mass production model C1E3 of this pump was fabricated as a short-term assist pump. This pump has a Normalized Index of Hemolysis of 0.0007 mg/100L and the estimated wear life of the impeller bearings is longer than 8 years. The C1E3 will meet the clinical requirements as a cardiopulmonary bypass pump. For the next step, a miniaturized pivot bearing centrifugal blood pump P1-601 has been developed for use as a permanently implantable device after design optimization. The evolution from C1E3 to the PI-601 converts this pivot bearing centrifugal pump as a totally implantable centrifugal pump. A pivot bearing centrifugal pump will become an ideal assist pump for the patients with failing heart. PMID:9195240

Nakazawa, T; Ohara, Y; Benkowski, R; Makinouchi, K; Takami, Y; Ohtsubo, S; Kawahito, K; Tasai, K; Glueck, J; Noon, G P; Sueoka, A; Schmallegger, H; Schima, H; Wolner, E; Nosé, Y

1997-04-01

370

Efficiency-A Pump Engineering Nemesis?  

E-print Network

speed (S) yields s ~s {NP~HRr'75 (1) for single suction impellers and Ns (NPSHR) 0.75 (2) S - 1.414 r-H for double suction impellers. The significance of these two relationships is that for a given limit on S and number of stages, insufficient... speed (S) yields s ~s {NP~HRr'75 (1) for single suction impellers and Ns (NPSHR) 0.75 (2) S - 1.414 r-H for double suction impellers. The significance of these two relationships is that for a given limit on S and number of stages, insufficient...

McGuire, J. T.

371

Characterisation of a small viscous flow turbine  

SciTech Connect

The result of experimental and numerical study that was undertaken to determine the performance characteristics of viscous flow turbines is presented. It is anticipated that these devices may find use in applications such as small power sources for electronic appliances and micro-combined heat and power applications. In the numerical work that was carried out to broaden the experimental results, commercial CFD solver Fluent 6.2 was used while accompanying software, Gambit 3.2, was used for performing the necessary pre-processing. The results of the experimental study indicate that the adiabatic efficiency of these machines is around 25%. The main reasons for the low efficiency have been identified to be, parasitic losses in the bearing, viscous losses in the end walls, and other dissipative losses in the plenum chamber that also significantly contribute to the low efficiencies of these devices. If these parasitic losses can be minimised the turbine could potentially operate with an adiabatic expansion efficiency close to the theoretical limit of around 40%. (author)

Lemma, E.; Deam, R.T.; Toncich, D. [Industrial Research Institute Swinburne, Faculty of Engineering and Industrial Sciences, P.O. Box 218, Hawthorn, Victoria 3122 (Australia); Collins, R. [VR-Tech Ltd., Level 9, 440 Collins Street, Melbourne, Victoria 3000 (Australia)

2008-10-15

372

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

Microsoft Academic Search

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,

S. Colantuoni; A. Colella

1993-01-01

373

Investigation of combined diffusers as part of stages with solid impellers in the range of Mach numbers M u >1  

Microsoft Academic Search

Further increases in energy efficiency and decreases in mass and size indices of centrifugal refrigeration compressors (CRC) are possible by creating new designs based on compressor stages with solid impellers (SI) and combined diffusers (CD). Use of SI in CRC which, as a rule, operate with high rated Mach numbers has a lot of promise since the presence of the

M. V. Golovin; A. S. Nuzhdin; I. N. Sukhomlinov; A. D. Slavutskii

1992-01-01

374

Flow field analysis of radial and backswept centrifugal compressor impellers. I - Flow measurements using a laser velocimeter  

Microsoft Academic Search

The internal flow in 2 centrifugal impellers with radial and backswept discharge, but otherwise identical design, has been investigated at tip speeds of 300 m\\/s. A laser velocimeter was applied for a detailed flow analysis, in addition to conventional flow probing and instantaneous wall pressure recordings. While the inducer flow patterns develop similarly up to a 3D flow separation at

D. Eckardt

1979-01-01

375

Winding for linear pump  

DOEpatents

A winding and method of winding for a submersible linear pump for pumping liquid sodium are disclosed. The pump includes a stator having a central cylindrical duct preferably vertically aligned. The central vertical duct is surrounded by a system of coils in slots. These slots are interleaved with magnetic flux conducting elements, these magnetic flux conducting elements forming a continuous magnetic field conduction path along the stator. The central duct has placed therein a cylindrical magnetic conducting core, this core having a cylindrical diameter less than the diameter of the cylindrical duct. The core once placed to the duct defines a cylindrical interstitial pumping volume of the pump. This cylindrical interstitial pumping volume preferably defines an inlet at the bottom of the pump, and an outlet at the top of the pump. Pump operation occurs by static windings in the outer stator sequentially conveying toroidal fields from the pump inlet at the bottom of the pump to the pump outlet at the top of the pump. The winding apparatus and method of winding disclosed uses multiple slots per pole per phase with parallel winding legs on each phase equal to or less than the number of slots per pole per phase. The slot sequence per pole per phase is chosen to equalize the variations in flux density of the pump sodium as it passes into the pump at the pump inlet with little or no flux and acquires magnetic flux in passage through the pump to the pump outlet. 4 figs.

Kliman, G.B.; Brynsvold, G.V.; Jahns, T.M.

1989-08-22

376

Ion pump provides increased vacuum pumping speed  

NASA Technical Reports Server (NTRS)

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.

1965-01-01

377

Investigation of the axial and radial thrusts in a centrifugal pump  

E-print Network

of impeller. The value of K was controlled by the impeller back-vanes. To reduce the back shroud pressure (axial thrust), a set of impeller back-vanes was used. Hence, fluid inside the clearance between impeller back-vanes and housing wall was rotated at a... of impeller. The value of K was controlled by the impeller back-vanes. To reduce the back shroud pressure (axial thrust), a set of impeller back-vanes was used. Hence, fluid inside the clearance between impeller back-vanes and housing wall was rotated at a...

Park, Chong Hwan

2012-06-07

378

Vortex design of a diagonal flow impeller with high specific speed  

NASA Astrophysics Data System (ADS)

The 'vortex design' method applied to an axial flow compressor stage has been extended to a diagonal flow impeller with high specific speed. For a given type of vortex flow, the through flow problem is solved by the streamline curvature method, and a blade element is determined on the basis of this solution. However, for any vortex type except free vortex, the exit flow condition changes due to a secondary flow induced by vortices shed from the trailing edges. The given vortex type can be obtained by correcting this effect with a so-called secondary flow theory.The validity of this method has been examined in experiments on three kinds of vortex flows: free vortex type, and constant tangential velocity types with or without correction of the secondary flow effects.

Kamada, Yoshihisa; Yamaguchi, Sumio; Sasaki, Kazuto; Inoue, Masahiro

1986-09-01

379

Electrical method and apparatus for impelling the extruded ejection of high-velocity material jets  

DOEpatents

A method and apparatus (10, 40) for producing high-velocity material jets provided. An electric current pulse generator (14, 42) is attached to an end of a coaxial two-conductor transmission line (16, 44) having an outer cylindrical conductor (18), an inner cylindrical conductor (20), and a solid plastic or ceramic insulator (21) therebetween. A coxial, thin-walled metal structure (22, 30) is conductively joined to the two conductors (18, 20) of the transmission line (16, 44). An electrical current pulse applies magnetic pressure to and possibly explosively vaporizes metal structure (22), thereby collapsing it and impelling the extruded ejection of a high-velocity material jet therefrom. The jet is comprised of the metal of the structure (22), together with the material that comprises any covering layers (32, 34) disposed on the structure. An electric current pulse generator of the explosively driven magnetic flux compression type or variety (42) may be advantageously used in the practice of this invention.

Weingart, Richard C. (Livermore, CA)

1989-01-01

380

QUANTITATIVE STOCHASTIC HOMOGENIZATION OF VISCOUS HAMILTON-JACOBI EQUATIONS  

E-print Network

. stochastic homogenization, error estimate, convergence rate, viscous Hamilton-Jacobi equation, first of propagation property possessed by first-order Hamilton-Jacobi equations. The latter property is essentiallyQUANTITATIVE STOCHASTIC HOMOGENIZATION OF VISCOUS HAMILTON-JACOBI EQUATIONS SCOTT N. ARMSTRONG

Paris-Sud XI, Université de

381

Poloidal variation of viscous forces in the banana collisionality regime  

SciTech Connect

The poloidal variation of the parallel viscous and heat viscous forces are determined for the first time using a rigorous Chapman- Enskog-like approach that has been developed recently. It is shown that the poloidal variation is approximately proportional to the poloidal distribution of the trapped particles, which are concentrated on the outer edge (large major radius side) of the tokamak.

Wang, J.P.; Callen, J.D.

1992-12-01

382

Atypical viscous fracture of human femurs1 Zohar Yosibasha,  

E-print Network

on probable damage of the trabecular bone that occurs prior to the catastrophic fracture of the cortical surface layer. Keywords: femur, fracture, creep7 1. Introduction8 Bone tissue exhibits both viscousAtypical viscous fracture of human femurs1 Zohar Yosibasha, , Romina Plitman Mayoa , Charles

Yosibash, Zohar

383

Contemporary Mathematics Numerical Simulation of Gas Bubbles Rising in Viscous  

E-print Network

Contemporary Mathematics Numerical Simulation of Gas Bubbles Rising in Viscous Liquids at High- duced in the context of gas bubbles rising in viscous liquids, e.g. air bubbles rising in water. Key on a supercomputer. Finally, the use of a non-inertial, moving reference frame attached to the rising bubble

Lin, Ping

384

Accurate viscous free surfaces for buckling, coiling, and rotating liquids  

Microsoft Academic Search

We present a fully implicit Eulerian technique for simulating free surface viscous liquids which eliminates artifacts in previous approaches, efficiently supports variable viscosity, and allows the simulation of more compelling viscous behaviour than previously achieved in graphics. Our method exploits a variational principle which automatically enforces the complex boundary condition on the shear stress at the free surface, while giving

Christopher Batty; Robert Bridson

2008-01-01

385

Open-Source Syringe Pump Library  

PubMed Central

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

Wijnen, Bas; Hunt, Emily J.; Anzalone, Gerald C.; Pearce, Joshua M.

2014-01-01

386

Multiple pump housing  

DOEpatents

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.

Donoho, II, Michael R. (Edelstein, IL); Elliott; Christopher M. (Metamora, IL)

2010-03-23

387

NACHOS2. Incompressible Viscous Fluid Dynamics  

SciTech Connect

NACHOS2 is a finite element program designed for the analysis of two-dimensional, incompressible viscous fluid flow problems. The basic flows considered may be isothermal, nonisothermal, or may involve other physical processes, such as mass transport. Both steady and transient flows may be analyzed. The class of problems treated are those described by the two-dimensional (plane or axisymmetric) incompressible form of the Navier-Stokes equations. An energy transport equation is included in the formulation for problems in which heat transfer effects are important. Two auxiliary transport equations can be added to describe other physical processes,e.g. mass transfer, chemical reactions. Among the specific types of flow problems treated are: isothermal flow; forced, free, or mixed convection; conjugate heat transfer; flow in saturated porous media with or without heat transfer; and inelastic, non-Newtonian flows with or without heat transfer. Other problem classes are possible depending on the specific definitions applied to the auxiliary transport equations.

Gartling, D.K. [Sandia National Labs., Albuquerque, NM (United States)

1992-02-21

388

Electromagnetic properties of viscous charged fluids  

E-print Network

We provide a general theoretical framework to describe the electromagnetic properties of viscous charged fluids, consisting for example of electrons in certain solids or plasmas. We confirm that finite viscosity leads to multiple modes of evanescent electromagnetic waves at a given frequency, one of which is characterized by a negative index of refraction, as previously discussed in a simplified model by one of the authors. In particular we explain how optical spectroscopy can be used to probe the viscosity. We concentrate on the impact of this on the coefficients of refraction and reflection at the sample-vacuum interface. Analytical expressions are obtained relating the viscosity parameter to the reflection and transmission coefficients of light. We demonstrate that finite viscosity has the effect to decrease the reflectivity of a metallic surface, while the electromagnetic field penetrates more deeply. While on a phenomenological level there are similarities to the anomalous skin effect, the model presente...

Forcella, Davide; Valentinis, Davide; van der Marel, Dirk

2014-01-01

389

Coupling relativistic viscous hydrodynamics to Boltzmann descriptions  

SciTech Connect

Models of relativistic heavy-ion collisions typically involve both a hydrodynamic module to describe the high-density liquidlike phase and a Boltzmann module to simulate the low-density breakup phase, which is gaslike. Coupling the prescriptions is more complicated for viscous prescriptions if one wants to maintain continuity of the entire stress-energy tensor and currents. Derivations for the viscosity for a gas are reviewed, which then lead to expressions for changes in the phase-space occupation based on simple relaxation-time pictures of viscosity. These expressions are shown to consistently reproduce the nonequilibrium components of the stress-energy tensor. An algorithm for generating a Monte Carlo sampling of particles with which to initiate the Boltzmann calculations is also presented.

Pratt, Scott; Torrieri, Giorgio [Department of Physics and Astronomy and National Superconducting Cyclotron Laboratory, Michigan State University, East Lansing, Michigan 48824 (United States); Institut fuer Theoretische Physik, J. W. Goethe Universitaet, Max Von Laue Strasse 1, Frankfurt A.M. (Germany)

2010-10-15

390

A numerical study of viscous breaking waves  

NASA Astrophysics Data System (ADS)

Small-scale viscous breaking waves have been simulated for a range of conditions. The numerical algorithm solves the coupled Navier-Stokes equations, together with the nonlinear free-surface boundary conditions on a moving grid. Adaptive mesh refinement and a new grid generation methodology have been implemented. While the results are similar to previous simulations, the new algorithm is more robust in the limit of very steep waves (k?>1). Longer, more energetic waves have been simulated. The phenomenology of the breaking waves will be presented. The production of vorticity during breaking and the subsequent dissipation of wave energy will be discussed. Preliminary simulations of three-dimensional waves will be presented.

Leighton, Richard

2003-11-01

391

Experimental study of highly viscous impinging jets  

SciTech Connect

The objective of this research is to study the behavior of highly viscous gravity-driven jets filling a container. Matters of interest are the formation of voids in the fluid pool during the filling process and the unstable behavior of the fluid in the landing region which manifests itself as an oscillating motion. The working fluids used in this research are intended to simulate the flow behavior of molten glass. Qualitative and quantitative results are obtained in a parametric study. The fraction of voids present in the fluid pool after the filling of the container is measured for different parameter values of viscosity and mass flow rate. Likewise, frequencies of the oscillating jet are measured. Results are inconclusive with regard to a correlation between parameter settings and void fractions. As for frequencies, power law correlations are established.

Gomon, M. [Univ. of Texas, Austin, TX (United States). Dept. of Mechanical Engineering

1998-12-01

392

Formulating Viscous Hydrodynamics for Large Velocity Gradients  

E-print Network

Viscous corrections to relativistic hydrodynamics, which are usually formulated for small velocity g radients, have recently been extended from Navier-Stokes formulations to a class of treatments based on Israel-Stewart equations. Israel-Stewart treatments, which treat the spatial components of the s tress-energy tensor tau_ij as dynamical objects, introduce new parameters, such as the relaxati on times describing non-equilibrium behavior of the elements tau_ij. By considering linear resp onse theory and entropy constraints, we show how the additional parameters are related to fluctuatio ns of tau_ij. Furthermore, the Israel-Stewart parameters are analyzed for their ability to prov ide stable and physical solutions for sound waves. Finally, it is shown how these parameters, which are naturally described by correlation functions in real time, might be constrained by lattice calcu lations, which are based on path-integral formulations in imaginary time.

Scott Pratt

2007-11-25

393

Inert gas ups viscous oil production  

Microsoft Academic Search

One of the newest heavy oil-recovery techniques is that of cyclic injecting an inert gas of carbon dioxide and nitrogen in a producing well. This method has increased producing rates substantially in recent field tests. The experimental project is located in the Taylor Ina Field of Medina County in Southwest Texas. The wells previously pumped a few barrels per day,

Davison

1965-01-01

394

Three-dimensional viscous rotor flow calculations using a viscous-inviscid interaction approach  

NASA Technical Reports Server (NTRS)

A three-dimensional viscous-inviscid interaction analysis was developed to predict the performance of rotors in hover and in forward flight at subsonic and transonic tip speeds. The analysis solves the full-potential and boundary-layer equations by finite-difference numerical procedures. Calculations were made for several different model rotor configurations. The results were compared with predictions from a two-dimensional integral method and with experimental data. The comparisons show good agreement between predictions and test data.

Chen, Ching S.; Bridgeman, John O.

1990-01-01

395

Variable Frequency Pump Drives  

E-print Network

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... is about to have a dramatic effect on many basic applications that exist for centrifugal pumps and their future standardization. VARIABLE SPEED PUMP OPERATION Changing the speed of the centrifugal pump driver is not a new development. Its advantages...

Karassik, I. J.; Petraccaro, L. L.; McGuire, J. T.

396

Optimal bearing gap of a multiarc radial bearing in a hydrodynamically levitated centrifugal blood pump for the reduction of hemolysis.  

PubMed

We have developed a hydrodynamically levitated centrifugal pump as a bridge-to-decision device. The purpose of the present study is to determine the optimal bearing gap of a multiarc radial bearing in the developed blood pump for the reduction of hemolysis. We prepared eight pump models having bearing gaps of 20, 30, 40, 80, 90, 100, 180, and 250??m. The driving conditions were set to a pressure head of 200?mm?Hg and a flow rate of 4?L/min. First, the orbital radius of the impeller was measured for the evaluation of the impeller stability. Second, the hemolytic property was evaluated in an in vitro hemolysis test. As a result, the orbital radius was not greater than 15??m when the bearing gap was between 20 and 100??m. The relative normalized index of hemolysis (NIH) ratios in comparison with BPX-80 were 37.67 (gap: 20??m), 0.95 (gap: 30??m), 0.96 (gap: 40??m), 0.82 (gap: 80??m), 0.77 (gap: 90??m), 0.92 (gap: 100??m), 2.76 (gap: 180??m), and 2.78 (gap: 250??m). The hemolysis tended to increase at bearing gaps of greater than 100??m due to impeller instability. When the bearing gap decreased from 30 to 20??m, the relative NIH ratios increased significantly from 0.95 to 37.67 times (P?pump for the reduction of hemolysis. PMID:25234763

Kosaka, Ryo; Yasui, Kazuya; Nishida, Masahiro; Kawaguchi, Yasuo; Maruyama, Osamu; Yamane, Takashi

2014-09-01

397

Geometric optimization of a step bearing for a hydrodynamically levitated centrifugal blood pump for the reduction of hemolysis.  

PubMed

A hydrodynamically levitated centrifugal blood pump with a semi-open impeller has been developed for mechanical circulatory assistance. However, a narrow bearing gap has the potential to cause hemolysis. The purpose of the present study is to optimize the geometric configuration of the hydrodynamic step bearing in order to reduce hemolysis by expansion of the bearing gap. First, a numerical analysis of the step bearing, based on lubrication theory, was performed to determine the optimal design. Second, in order to assess the accuracy of the numerical analysis, the hydrodynamic forces calculated in the numerical analysis were compared with those obtained in an actual measurement test using impellers having step lengths of 0%, 33%, and 67% of the vane length. Finally, a bearing gap measurement test and a hemolysis test were performed. As a result, the numerical analysis revealed that the hydrodynamic force was the largest when the step length was approximately 70%. The hydrodynamic force calculated in the numerical analysis was approximately equivalent to that obtained in the measurement test. In the measurement test and the hemolysis test, the blood pump having a step length of 67% achieved the maximum bearing gap and reduced hemolysis, as compared with the pumps having step lengths of 0% and 33%. It was confirmed that the numerical analysis of the step bearing was effective, and the developed blood pump having a step length of approximately 70% was found to be a suitable configuration for the reduction of hemolysis. PMID:23834855

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

2013-09-01

398

A quantitative visualization study of flow in a scaled-up model of a centrifugal blood pump.  

PubMed

A quantitative flow visualization study of a scaled-up model of a centrifugal blood pump was performed. Since the size of the scaled-up model was three times as large as the original pump under development, and the kinematic viscosity of the saline solution used as the working fluid was approximately one-third that of the blood, we obtained a similar flow at one twenty-seventh the angular velocity of the original pump. The flow was visualized by seeding the saline solution with neutrally buoyant particles and by illuminating the model with a laser light sheet. Since the gap flow behind the impeller is important for thrombus formation, it was recorded by a high-speed video camera, and the velocity field was evaluated automatically by particle tracking velocimetry. It was shown that in the gap behind the impeller there existed a region where the velocity profile was almost flat which can be called a core region. The results indicated the effectiveness of the present visualization technique for centrifugal blood pumps. PMID:8712957

Ikeda, T; Yamane, T; Orita, T; Tateishi, T

1996-02-01

399

In vivo evaluation of the "TinyPump" as a pediatric left ventricular assist device.  

PubMed

Pediatric patients with end-stage heart failure require mechanical circulatory support (MCS) just as adults do. In order to meet the special requirements for neonates' and infants' MCS, pediatric circulatory support devices must be compact with low priming volume, easily controllable with low flow, less traumatic for blood cells and tissues, and biocompatible with minimum anticoagulation. We have designed and developed a miniature rotary centrifugal blood pump, "TinyPump," with a priming volume of 5 mL, which has already demonstrated its controllable performance for low flow and durability in vitro. To evaluate the feasibility of the TinyPump as a left ventricular assist device (LVAD) suitable for neonates and infants, we have examined the biocompatibility and hemodynamic performance of the TinyPump in a pediatric animal model using Shiba goats. The TinyPump is a miniaturized centrifugal pump weighing 150 g comprising a disposable pump head with a 30-mm diameter impeller having six straight-vanes and a reusable motor driver. The impeller in the pump head is supported by a hydrodynamic bearing at its center and is driven by radial magnetic force coupled to the motor driver. TinyPump implantations were performed in 22 Shiba goats (17 female and 5 male), with body weights ranging from 8.4 to 27.2 kg. Under gas anesthesia, via left lateral thoracotomy, a 22 Fr inflow cannula was inserted through the left ventricular apex, while a 6-mm outflow graft was anastomosed to the descending aorta, which were then connected to a TinyPump mounted on the animal's back. Postoperative hemodynamic monitoring included heart rate, arterial and central venous pressure, pump flow, and rotation speed. Target pump flow in all animals was maintained at 0.9 ± 0.1 L/min, which is approximately half the normal pulmonary artery flow measured in control animals. Blood samples were collected to evaluate peripheral organ functions, hemolysis, and thrombosis. Goats were divided into three groups-acute phase (6 h; n = 4), subchronic phase (6 h 2 postoperative days [POD]; n = 11), and chronic phase (3 POD-16 POD; n = 8)-based on their survival duration. In the early experiments, hemolysis and thrombi formation at the impeller bearing resulted in termination of the study. Subsequent modifications of the bearing design, pump housing design, and magnetic coupling force helped to minimize the hemolysis and thrombi formation, prolonging the survival duration of the Shiba goats to 2 weeks with minimum adverse effects on the blood components and organ functions. With further experiments and improvements in pump durability and hemocompatibility, the TinyPump can serve as a suitable circulatory support device for neonates and infants bridging to heart transplantation as well as to heart recovery. PMID:21595723

Kitao, Takashi; Ando, Yusuke; Yoshikawa, Masaharu; Kobayashi, Mariko; Kimura, Taro; Ohsawa, Hideyuki; Machida, Shinya; Yokoyama, Naoyuki; Sakota, Daisuke; Konno, Tomohiro; Ishihara, Kazuhiko; Takatani, Setsuo

2011-05-01

400

An experimental study of a small high-speed LH2 pump for rockets: Fluid dynamic performance  

NASA Astrophysics Data System (ADS)

A small high speed rocket engine hydrogen pump was designed, fabricated, and tested at the National Aerospace Laboratory (NAL)/National Space Development Agency (NASDA) turbopump test facility. The pump uses liquid nitrogen and liquid hydrogen as the working fluid in order to determine its associated fluid dynamic performance. The focus is on the overall and the suction performance. The overall performance was judged to be good. However, at high speed and high pressure conditions (50,000 rpm) a clearance occurred between the pump casing and the pump outlet guide vane. This resulted in the pump outlet guide vane showing reduced performance as compared to the low speed conditions (30,000 rpm). Design of the pump outlet guide vane is subsequently necessary to improve high speed pump performance. Prediction of the impeller performance was found to be in good agreement with the experimental results when pump efficiency is taken into consideration. In addition, the inducer showed a smaller required Net Positive Suction Head (NPSH) value than the design value, in fact, it could operate even in a two phase flow condition at the pump inlet.

Yamada, Hitoshi; Watanabe, Yoshiaki; Hirota, Kunio

1991-11-01

401

Progress In Incompressible Pump Flow Calculations  

NASA Technical Reports Server (NTRS)

Steady and unsteady flows for propulsion systems are 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. Current computations use one equation Baldwin-Barth turbulence model which is derived from a simplified form of the standard kappa - epsilon model equations. The resulting computer code is applied to the flow analysis inside an advanced rocket pump impeller in steadily rotating reference frames. Numerical results are compared with experimental measurements. The effects of exit and shroud cavities with the leak-age flow are investigated. Time-accurate incompressible Navier-Stokes formulation with the overlapped grid scheme capability was evaluated by using MIT flapping foil experiment. The grid dependency, turbulence model effects, and the effect of order of differencing were investigated. Numerical results were compared against experimental data. The resulting procedure were applied to unsteady flapping foil calculations. Two upstream NACA 0025 foils perform high frequency synchronized motion and generate unsteady flow conditions to the downstream larger stationary foil. Comparison between unsteady experimental data and numerical results from two different moving boundary procedures will be presented.

Kiris, Cetin; Kwak, Dochan; Kutler, Paul (Technical Monitor)

1994-01-01

402

Initial in vivo evaluation of the newly developed axial flow turbo pump with hydrodynamic bearings.  

PubMed

An implantable, compact rotary blood pump has been newly developed using an axial flow turbo pump with hydrodynamic bearings. The rotating impeller, which is hydrodynamically levitated with the assistance of repulsive magnetic force, has no contact with the inner surface of the pump. To evaluate the hemodynamic performance and biocompatibility, the pump was installed into four calves for up to 90 days. The pump was installed in the left heart bypass fashion, and placed paracorporeally in the first two calves and in the thoracic cavity in the other two calves. All calves received anticoagulation and antiaggregation therapy during the study. Aortic pressure, heart rate and pump-operating parameters were continuously measured. Hematologic and biochemical tests to evaluate anemia, hepato-renal function and the extent of hemolysis were performed on schedule. Each calf was killed at the termination of the experiments, and pathological analysis for the biocompatibility of the pump system was performed, including the thrombi in the device, emboli in the systemic organs and signs of infection. The pump stably produced a flow of 5 l/min. Each calf was supported for 78, 50, 90 and 90 days, respectively, with no incidence of hemorrhage, organ failure or significant hemolysis. No thrombus formation or mechanical wearing was observed inside the pump. There was no evidence of heat injury around the pump. Device-related infections were observed, but the severity of infection was mild in the implant case compared to the paracorporeal case. The pump demonstrated acceptable hemodynamic performance and biocompatibility in the initial in vivo testing. PMID:21207088

Tanaka, Hideyuki; Tsukiya, Tomonori; Tatsumi, Eisuke; Mizuno, Toshihide; Hidaka, Tatsuya; Okubo, Takeshi; Osada, Toshiyuki; Miyamoto, Shinji; Taenaka, Yoshiyuki

2011-03-01

403

Continuously pumping and reactivating gas pump  

DOEpatents

Apparatus for continuous pumping using cycling cyropumping panels. A plurality of liquid helium cooled panels are surrounded by movable nitrogen cooled panels the alternatively expose or shield the helium cooled panels from the space being pumped. Gases condense on exposed helium cooled panels until the nitrogen cooled panels are positioned to isolate the helium cooled panels. The helium cooled panels are incrementally warmed, causing captured gases to accumulate at the base of the panels, where an independent pump removes the gases. After the helium cooled panels are substantially cleaned of condensate, the nitrogen cooled panels are positioned to expose the helium cooled panels to the space being pumped.

Batzer, Thomas H. (Livermore, CA); Call, Wayne R. (Tracy, CA)

1984-01-01

404

Effect of impeller type and mechanical agitation on the mass transfer and power consumption aspects of ASBR operation treating synthetic wastewater.  

PubMed

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

Michelan, Rogério; Zimmer, Thiago R; Rodrigues, José A D; Ratusznei, Suzana M; de Moraes, Deovaldo; Zaiat, Marcelo; Foresti, Eugenio

2009-03-01

405

Notes 11. Modal Analysis of MDOF Systems with Viscous Damping  

E-print Network

MEEN 617 HD 11 Modal Analysis of MDOF Systems with Viscous Damping L. San Andr?s ? 2008 1 MEEN 617 Handout #11 MODAL ANALYSIS OF MDOF Systems with VISCOUS DAMPING ^ Symmetric Motion of a n-DOF linear system... Systems with Viscous Damping L. San Andr?s ? 2008 2 where ()? ?? ?? f is a nxn square matrix. The system of homogeneous equations (4) has a nontrivial solution if the determinant of the system of equation equals zero, i.e. () () 2 32 01 2 3 2 0...

San Andres, Luis

2008-01-01

406

Method for formation of subsurface barriers using viscous colloids  

DOEpatents

A method is described for formation of subsurface barriers using viscous liquids where a viscous liquid solidifies at a controlled rate after injection into soil and forms impermeable isolation of the material enclosed within the subsurface barriers. The viscous liquid is selected from the group consisting of polybutenes, polysiloxanes, colloidal silica and modified colloidal silica of which solidification is controlled by gelling, cooling or cross-linking. Solidification timing is controlled by dilution, addition of brines, coating with alumina, stabilization with various agents and by temperature. 17 figs.

Apps, J.A.; Persoff, P.; Moridis, G.; Pruess, K.

1998-11-17

407

Method for formation of subsurface barriers using viscous colloids  

DOEpatents

A method for formation of subsurface barriers using viscous liquids where a viscous liquid solidifies at a controlled rate after injection into soil and forms impermeable isolation of the material enclosed within the subsurface barriers. The viscous liquid is selected from the group consisting of polybutenes, polysilotanes, colloidal silica and modified colloidal silica of which solidification is controlled by gelling, cooling or cross-linking. Solidification timing is controlled by dilution, addition of brines, coating with alumina, stabilization with various agents and by temperature.

Apps, John A. (Lafayette, CA); Persoff, Peter (Piedmont, CA); Moridis, George (Oakland, CA); Pruess, Karsten (Berkeley, CA)

1998-01-01

408

Viscous coalescence of droplets: A lattice Boltzmann study  

NASA Astrophysics Data System (ADS)

The coalescence of two resting liquid droplets in a saturated vapor phase is investigated by Lattice Boltzmann simulations in two and three dimensions. We find that, in the viscous regime, the bridge radius obeys a t1/2-scaling law in time with the characteristic time scale given by the viscous time. Our results differ significantly from the predictions of existing analytical theories of viscous coalescence as well as from experimental observations. While the underlying reason for these deviations is presently unknown, a simple scaling argument is given that describes our results well.

Gross, M.; Steinbach, I.; Raabe, D.; Varnik, F.

2013-05-01

409

Testing viscous and anisotropic hydrodynamics in an exactly solvable case  

NASA Astrophysics Data System (ADS)

We exactly solve the one-dimensional boost-invariant Boltzmann equation in the relaxation time approximation for arbitrary shear viscosity. The results are compared with the predictions of viscous and anisotropic hydrodynamics. Studying different nonequilibrium cases and comparing the exact kinetic-theory results to the second-order viscous hydrodynamics results we find that recent formulations of second-order viscous hydrodynamics agree better with the exact solution than the standard Israel-Stewart approach. Additionally, we find that, given the appropriate connection between the kinetic and anisotropic hydrodynamics relaxation times, anisotropic hydrodynamics provides a very good approximation to the exact relaxation time approximation solution.

Florkowski, Wojciech; Ryblewski, Radoslaw; Strickland, Michael

2013-08-01

410

Active control of pressure, sound and velocity of centrifugal pumps  

NASA Astrophysics Data System (ADS)

Measurements of velocity, pressure, and sound were obtained in a centrifugal pump with a four blade impeller rotating at speeds between 1470 and 3510 rpm to improve understanding of noise generation and to investigate the feasibility of reducing fluid dynamic noise with active control. The velocity results show flow separation in the region near the shroud wall and at the suction surface of the blades with the flow driven inward by the adverse pressure gradient near the shroud wall. The frequency spectra of the pressure distributions obtained inside the pump casing at 3510 rpm showed a dominant frequency of 50 to 60 dB above the background level associated with the blade passing frequency of approximately 240 Hz. However, the saw-tooth waveform observed in the pressure characteristic also comprised of second and third harmonics of 45 to 55 dB and 35 to 45 dB above the background level and another 8 higher harmonics with diminishing amplitude as the frequency increased. The pressure distribution underwent a circumferential variation which was believed to stem from resonance or suppression of the 11 harmonic frequencies due to circumferential variation of the geometry of the scroll. All the waveforms inside the pump were generated by 11 sinusoids of different amplitudes. Only the first three harmonics contained sufficient energy to produce a detectable signature in the air-borne noise characteristics.

Tse, D. G.; Sabnis, J. S.; McDonald, H.; Whitelaw, James H.

1992-03-01

411

Secondary flow, separation and losses in the NACA 48-inch centrifugal impeller at design and off-design conditions  

Microsoft Academic Search

An elliptic flow calculation procedure has been used to model three-dimensional flow in the NACA 48-inch centrifugal impeller. The results demonstrate that fully elliptic steady flow calculations can be performed at design and off-design conditions. The calculations reproduce the measured overall performance and most of the features of the loss distributions observed in the NACA flow study. They give further

John Moore; Joan G. Moore

1988-01-01

412

Effect of specific heat ratio, impeller tip running clearance, and compressor insulation on high-pressure-ratio centrifugal compressor modeling  

Microsoft Academic Search

Results are displayed which show the effect of gas specific heat ratio, impeller tip running clearance, and compressor insulation on modeling of a high-pressure-ratio compressor's performance. The data were obtained using a low-speed-of-sound gas and a compressor previously tested extensively in air. Duplication of the air inlet specific heat ratio was found to be essential to modeling of the air-equivalent

J. A. Block; P. W. Runstadler Jr.

1975-01-01

413

Hypersonic Viscous Flow Over Large Roughness Elements  

NASA Technical Reports Server (NTRS)

Viscous flow over discrete or distributed surface roughness has great implications for hypersonic flight due to aerothermodynamic considerations related to laminar-turbulent transition. Current prediction capability is greatly hampered by the limited knowledge base for such flows. To help fill that gap, numerical computations are used to investigate the intricate flow physics involved. An unstructured mesh, compressible Navier-Stokes code based on the space-time conservation element, solution element (CESE) method is used to perform time-accurate Navier-Stokes calculations for two roughness shapes investigated in wind tunnel experiments at NASA Langley Research Center. It was found through 2D parametric study that at subcritical Reynolds numbers of the boundary layers, absolute instability resulting in vortex shedding downstream, is likely to weaken at supersonic free-stream conditions. On the other hand, convective instability may be the dominant mechanism for supersonic boundary layers. Three-dimensional calculations for a rectangular or cylindrical roughness element at post-shock Mach numbers of 4.1 and 6.5 also confirm that no self-sustained vortex generation is present.

Chang, Chau-Lyan; Choudhari, Meelan M.

2009-01-01

414

Chemical Methods for Ugnu Viscous Oils  

SciTech Connect

The North Slope of Alaska has large (about 20 billion barrels) deposits of viscous oil in Ugnu, West Sak and Shraeder Bluff reservoirs. These shallow reservoirs overlie existing productive reservoirs such as Kuparuk and Milne Point. The viscosity of the Ugnu reservoir on top of Milne Point varies from 200 cp to 10,000 cp and the depth is about 3300 ft. The same reservoir extends to the west on the top of the Kuparuk River Unit and onto the Beaufort Sea. The depth of the reservoir decreases and the viscosity increases towards the west. Currently, the operators are testing cold heavy oil production with sand (CHOPS) in Ugnu, but oil recovery is expected to be low (< 10%). Improved oil recovery techniques must be developed for these reservoirs. The proximity to the permafrost is an issue for thermal methods; thus nonthermal methods must be considered. The objective of this project is to develop chemical methods for the Ugnu reservoir on the top of Milne Point. An alkaline-surfactant-polymer (ASP) formulation was developed for a viscous oil (330 cp) where as an alkaline-surfactant formulation was developed for a heavy oil (10,000 cp). These formulations were tested in one-dimensional and quarter five-spot Ugnu sand packs. Micromodel studies were conducted to determine the mechanisms of high viscosity ratio displacements. Laboratory displacements were modeled and transport parameters (such as relative permeability) were determined that can be used in reservoir simulations. Ugnu oil is suitable for chemical flooding because it is biodegraded and contains some organic acids. The acids react with injected alkali to produce soap. This soap helps in lowering interfacial tension between water and oil which in turn helps in the formation of macro and micro emulsions. A lower amount of synthetic surfactant is needed because of the presence of organic acids in the oil. Tertiary ASP flooding is very effective for the 330 cp viscous oil in 1D sand pack. This chemical formulation includes 1.5% of an alkali, 0.4% of a nonionic surfactant, and 0.48% of a polymer. The secondary waterflood in a 1D sand pack had a cumulative recovery of 0.61 PV in about 3 PV injection. The residual oil saturation to waterflood was 0.26. Injection of tertiary alkaline-surfactant-polymer slug followed by tapered polymer slugs could recover almost 100% of the remaining oil. The tertiary alkali-surfactant-polymer flood of the 330 cp oil is stable in three-dimensions; it was verified by a flood in a transparent 5-spot model. A secondary polymer flood is also effective for the 330 cp viscous oil in 1D sand pack. The secondary polymer flood recovered about 0.78 PV of oil in about 1 PV injection. The remaining oil saturation was 0.09. The pressure drops were reasonable (<2 psi/ft) and depended mainly on the viscosity of the polymer slug injected. For the heavy crude oil (of viscosity 10,000 cp), low viscosity (10-100 cp) oil-in-water emulsions can be obtained at salinity up to 20,000 ppm by using a hydrophilic surfactant along with an alkali at a high water-to-oil ratio of 9:1. Very dilute surfactant concentrations (~0.1 wt%) of the synthetic surfactant are required to generate the emulsions. It is much easier to flow the low viscosity emulsion than the original oil of viscosity 10,000 cp. Decreasing the WOR reverses the type of emulsion to water-in-oil type. For a low salinity of 0 ppm NaCl, the emulsion remained O/W even when the WOR was decreased. Hence a low salinity injection water is preferred if an oil-in-water emulsion is to be formed. Secondary waterflood of the 10,000 cp heavy oil followed by tertiary injection of alkaline-surfactants is very effective. Waterflood has early water breakthrough, but recovers a substantial amount of oil beyond breakthrough. Waterflood recovers 20-37% PV of the oil in 1D sand pack in about 3 PV injection. Tertiary alkali-surfactant injection increases the heavy oil recovery to 50-70% PV in 1D sand packs. As the salinity increased, the oil recovery due to alkaline surfactant flood increased, but water-in-oil emulsion was p

Kishore Mohanty

2012-03-31

415

Hypersonic viscous flow over large roughness elements  

NASA Astrophysics Data System (ADS)

Viscous flow over discrete or distributed surface roughness has great implications for hypersonic flight due to aerothermodynamic considerations related to laminar-turbulent transition. Current prediction capability is greatly hampered by the limited knowledge base for such flows. To help fill that gap, numerical computations are used to investigate the intricate flow physics involved. An unstructured mesh, compressible Navier-Stokes code based on the space-time conservation element, solution element (CESE) method is used to perform time-accurate Navier-Stokes calculations for two roughness shapes investigated in wind tunnel experiments at NASA Langley Research Center. It was found through 2D parametric study that at subcritical Reynolds numbers, spontaneous absolute instability accompanying by sustained vortex shedding downstream of the roughness is likely to take place at subsonic free-stream conditions. On the other hand, convective instability may be the dominant mechanism for supersonic boundary layers. Three-dimensional calculations for both a rectangular and a cylindrical roughness element at post-shock Mach numbers of 4.1 and 6.5 also confirm that no self-sustained vortex generation from the top face of the roughness is observed, despite the presence of flow unsteadiness for the smaller post-shock Mach number case.

Chang, Chau-Lyan; Choudhari, Meelan M.

2011-06-01

416

Electromagnetic properties of viscous charged fluids  

E-print Network

We provide a general theoretical framework to describe the electromagnetic properties of viscous charged fluids, consisting for example of electrons in certain solids or plasmas. We confirm that finite viscosity leads to multiple modes of evanescent electromagnetic waves at a given frequency, one of which is characterized by a negative index of refraction, as previously discussed in a simplified model by one of the authors. In particular we explain how optical spectroscopy can be used to probe the viscosity. We concentrate on the impact of this on the coefficients of refraction and reflection at the sample-vacuum interface. Analytical expressions are obtained relating the viscosity parameter to the reflection and transmission coefficients of light. We demonstrate that finite viscosity has the effect to decrease the reflectivity of a metallic surface, while the electromagnetic field penetrates more deeply. While on a phenomenological level there are similarities to the anomalous skin effect, the model presented here requires no particular assumptions regarding the corpuscular nature of the charge liquid. A striking consequence of the branching phenomenon into two degenerate modes is the occurrence in a half-infinite sample of oscillations of the electromagnetic field intensity as a function of distance from the interface.

Davide Forcella; Jan Zaanen; Davide Valentinis; Dirk van der Marel

2014-06-05

417

Viscous friction of hydrogen-bonded matter.  

PubMed

Amontons' law successfully describes friction between macroscopic solid bodies for a wide range of velocities and normal forces. For the diffusion and forced sliding of adhering or entangled macromolecules, proteins, and biological complexes, temperature effects are invariably important, and a similarly successful friction law at biological length and velocity scales is missing. Hydrogen bonds (HBs) are key to the specific binding of biomatter. Here we show that friction between hydrogen-bonded matter obeys in the biologically relevant low-velocity viscous regime a simple law: the friction force is proportional to the number of HBs, the sliding velocity, and a friction coefficient ?(HB). This law is deduced from atomistic molecular dynamics simulations for short peptide chains that are laterally pulled over planar hydroxylated substrates in the presence of water and holds for widely different peptides, surface polarities, and applied normal forces. The value of ?(HB) is extrapolated from simulations at sliding velocities in the range from V = 10(-2) to 100 m/s by mapping on a simple stochastic model and turns out to be of the order of ?(HB) ? 10(-8) kg/s. The friction of a single HB thus amounts to the Stokes friction of a sphere with an equivalent radius of roughly 1 ?m moving in water. Cooperativity is pronounced: roughly three HBs act collectively. PMID:22098642

Erba?, Aykut; Horinek, Dominik; Netz, Roland R

2012-01-11

418

Viscous theory of surface noise interaction phenomena  

NASA Technical Reports Server (NTRS)

A viscous linear surface noise interaction problem is formulated that includes noise production by an oscillating surface, turbulent or vortical interaction with a surface, and scattering of sound by a surface. The importance of viscosity in establishing uniqueness of solution and partitioning of energy into acoustic and vortical modes is discussed. The results of inviscid two dimensional airfoil theory are used to examine the interactive noise problem in the limit of high reduced frequency and small Helmholtz number. It is shown that in the case of vortex interaction with a surface, the noise produced with the full Kutta condition is 3 dB less than the no Kutta condition result. The results of a study of an airfoil oscillating in a medium at rest are discussed. It is concluded that viscosity can be a controlling factor in analyses and experiments of surface noise interaction phenomena and that the effect of edge bluntness as well as viscosity must be included in the problem formulation to correctly calculate the interactive noise.

Yates, J. E.

1980-01-01

419

Successive bifurcations in directional viscous fingering  

NASA Astrophysics Data System (ADS)

Directional viscous-fingering experiments are reported which extend previous studies by Rabaud, Michalland, and Couder [Phys. Rev. Lett. 64, 184 (1990)]. With the external cylinder rotation speed Ve fixed at a small constant value, the counter-rotation speed of the inner cylinder Vi, which is then the single control parameter of the experiment, was increased or decreased in small steps. Beyond the primary planar-cellular bifurcation of the air-oil interface, a secondary bifurcation was observed to a state with uniform space-filling traveling cells, followed by a spatial period-doubling bifurcation. Close to these bifurcations, we also observed transient states with solitary traveling cells, traveling domains of tilted cells, and mixed states of coexisting large and small traveling cells. These states resemble observations in recent directional-solidification experiments on liquid crystals and eutectic alloys. We discuss these results in the context of recent theoretical descriptions of parity-breaking tilt bifurcations and spatial period-doubling bifurcations based on k-2k mode-interaction models.

Cummins, H. Z.; Fourtune, L.; Rabaud, M.

1993-03-01

420

Experimental and computational results from the NASA Lewis low-speed centrifugal impeller at design and part-flow conditions  

SciTech Connect

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.

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