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1

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.

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

2010-01-01

2

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

PubMed Central

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

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

2012-01-01

3

Numerical Simulation of Transient flow through Single Blade Centrifugal Pump Impellers with Tipgap Leakage  

Microsoft Academic Search

This paper is concerned with the application of Computational Fluid Dynamics (CFD) to a low specific speed (Ns=60) single blade impeller. Single blade centrifugal pump impellers are the extreme example of impeller design, with gross deviation from conventional design practice. A time accurate three- dimensional viscous flow simulation is performed, using the multiple frames of reference sliding mesh technique, at

BRIAN DE SOUZA; JOHN DALY; ANDREW NIVEN; PATRICK FRAWLEY

2006-01-01

4

Rotordynamic forces on centrifugal pump impellers  

NASA Technical Reports Server (NTRS)

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

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

1987-01-01

5

Rotordynamic forces on centrifugal pump impellers  

NASA Astrophysics Data System (ADS)

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

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

6

High Head Unshrouded Impeller Pump Stage Technology  

NASA Technical Reports Server (NTRS)

Objective to develop an unshrouded impeller design, which a meets the performance requirements of a 3-stage fuel pump with a 2-stage pump design, has been accomplished. Performance of the baseline unshrouded impeller has been experimentally verified. Unshrouded impeller trade study and final 6+6 unshrouded impeller configuration has been presented. Structurally viable, 6+6-impeller design concept has been produced. Based on results presented in this study, at a nominal 10% tip-clearance, the 6+6 impeller design would increase payload to orbit by almost 625 lbs. per engine. The RLV vehicle requires 7 engines, therefore, application of high head unshrouded technology would increase payload capability by as much as 4,375 lbs. per vehicle.

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

7

Trim or Replace Impellers on Oversized Pumps  

SciTech Connect

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

Not Available

2006-09-01

8

Effect of impeller flow path on pump performance and impeller stability of the monopivot circulatory pump.  

PubMed

The effect of a cutout on the pump pressure-flow characteristics and the impeller stability was quantified using computational fluid dynamics analysis in order to provide good hemocompatibility of the monopivot extracorporeal circulation pump. As a result, the following findings were clarified. The pump pressure is lower in the cutout model than in the no-cutout model. The impeller stability with respect to the buoyancy of the impeller is better in the cutout model than in the no-cutout model. The impeller stability with respect to the impeller tilt is better in the cutout model than in the no-cutout model. Therefore, the cutout model, in which the geometry corresponds to the commercialized pump, was likely to be better than the no-cutout model because the stability that has the possibility to decrease the gap instantaneously to increase hemolysis despite the impeller rotational speed slightly. PMID:24110293

Nishida, Masahiro; Nakayama, Kento; Kosaka, Ryo; Maruyama, Osamu; Kawaguchi, Yasuo; Kuwana, Katsuyuki; Yamane, Takashi

2013-01-01

9

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

10

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

11

Some unsteady fluid forces on pump impellers  

NASA Astrophysics Data System (ADS)

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

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

1992-12-01

12

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

13

Turbo-pump with isolated two stage impellers for future rocket engine (Trial to drive impellers independently)  

NASA Astrophysics Data System (ADS)

To suppress the cavitation in the impellers and to make the turbo-pump lives longer, the inducer was separated from the main impeller and both impellers were driven independently. The performance of the pump and the flow conditions around the impellers were investigated experimentally and the following results were obtained. (1)The main impeller contributes to the flow interaction between the inducer and the main impeller. (2)The rotational speeds of both impellers can be controlled independently in order to suppress simultaneously the cavitation not only in the main impeller, but also in the inducer.

Kanemoto, Toshiaki; Shimojyo, Makoto; Kawashima, Ryunosuke; Tanaka, Daisuke; Inagaki, Akira; Oba, Shin

2008-03-01

14

Evaluation of floating impeller phenomena in a Gyro centrifugal pump.  

PubMed

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

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

2013-01-01

15

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

16

A New Total Heart Design Via Implantable Impeller Pumps  

Microsoft Academic Search

Hemolysis and thrombosis have been considered as the main limitations of the impeller pump and other centrifugal pumps to total heart ap plications. One of the solutions is to choose the impeller shroud and vane ac cording to the stream surfaces of blood flow, so as to vanish the turbulence and stagnation which cause the hemolysis and thrombosis, respectively, in

Kun-Xi Qian

1990-01-01

17

Full Scale Evaluation of Waterjet Pump Impellers.  

National Technical Information Service (NTIS)

Full scale experiments were conducted with a U. S. Navy waterjet-powered planing boat to evaluate three different waterjet impeller/nozzle configurations. The configurations consisted of the standard impeller/nozzle combination currently installed on thes...

R. S. Alder S. B. Denny

1977-01-01

18

Nuclear reactor coolant pump impeller/shaft assembly  

SciTech Connect

A pump is described comprising: (a) a casing having an inlet and an outlet in fluid communication for circulating fluid coolant through the pump; (b) a shaft positioned in the casing; (c) an impeller nut connected to the shaft; (d) a lockbolt fixedly connecting the impeller nut relative to the shaft; (e) passageway means with first and second ends for directing fluid from the lockbolt to the shaft; (f) first conduit means formed in the impeller nut in fluid communication with the first end of the passageway means and the inlet of the casing; and (g) second conduit means formed in the impeller nut in fluid communication with the second end of the passageway means and the outlet of the casing. A portion of the fluid coolant circulating through the inlet of the casing is pumped through the first conduit means, through the passageway means, out the second conduit means and into the outlet of the casing.

Jenkins, L.S.

1987-09-01

19

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

20

Erosion corrosion of pump impeller of cyclic cooling water system  

Microsoft Academic Search

An impeller of a pump of cyclic cooling water system (CCWS) of power plant, failed after about 13years of service. Tolyltriazole (TT) is included in the water as corrosion inhibitor. Most of the surface of both blades was pitted, and clear grinding marks were noticeable. The pits are horseshoe-shaped. Examination of those pits revealed a pattern of dendrites on the

S. Ariely; A. Khentov

2006-01-01

21

CFD Analysis and Design Effects in a Radial Pump Impeller  

Microsoft Academic Search

The direct flow analysis in hydraulic turbomachines using Computational Fluid Dynamic (CFD) methods can provide a quite illuminating picture of the developed flow field and its detailed characteristics. A numerical model for the simulation of the 3-dimensional turbulent flow in centrifugal pump impellers is developed in the present work, solving the Reynolds Averaged Navier Stokes equations with the control volume

JOHN S. ANAGNOSTOPOULOS

2006-01-01

22

Improving centrifugal pump efficiency by impeller trimming  

Microsoft Academic Search

Centrifugal pumps as inevitable part of any desalination plant are significant consumers of energy. Due to high capacities of desalination plants, efficient operation of all their components, including centrifugal pumps is very important. It is often found that centrifugal pumps do not operate in their optimal points for various reasons. One of the methods to improve efficiency of centrifugal pump

Mario Šavar; Hrvoje Kozmar; Igor Sutlovi?

2009-01-01

23

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

24

The flow investigation inside a centrifugal pump impeller with laser Doppler velocimeter  

Microsoft Academic Search

The flow distribution in an oilfield injection-pump impeller at low specific speeds is measured by using a laser Doppler velocimeter. After measuring and analyzing the velocity and turbulence in the pump impeller the jet-wake flow in the impeller passage is shown.

Dunsong Xue; Zijing Sun; Jun Lu

1991-01-01

25

Proposal of Unique Process Pump with Floating Type Centrifugal Impeller (Preliminarily Report : Axial Thrust of Impeller with Driving Shaft)  

NASA Astrophysics Data System (ADS)

The authors have proposed the unique centrifugal pump, in which the impeller dose not have the driving shaft but is driven by the magnetic induction, namely Lorentz force, without the stay. Then, the rotating posture of the impeller is not stable, just like UFO. To make the rotating posture of the impeller stable irrespective of the operating condition, the pressure in the impeller casing was investigated experimentally while the impeller rotates at the steady state, as the preliminarily stage. The pressure, as well known, fluctuates periodically in response to the blade number. Besides, the pressure on the impeller shrouds decreases with the increase of the gap between the front shroud and the suction cover where the water leaks to the suction pipe, and is distorted in the peripheral direction. Such pressure conditions contribute directly to the hydraulic force acting on the impeller. The unstable behaviors of the impeller are induced from the above hydraulic forces, which change unsteadily in the radial and the peripheral directions in the impeller casing. The forces are affected by not only the operating condition but also the rotating posture of the impeller.

Kawashima, Ryunosuke; Kanemoto, Toshiaki; Sakamoto, Kengo; Uno, Mitsuo

2010-06-01

26

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

SciTech Connect

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. (University College of London (United Kingdom). Dept. of Mechanical Engineering)

1994-04-01

27

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

28

Fluid-structure interaction forces at pump-impeller-shroud surfaces for axial vibration analysis  

NASA Technical Reports Server (NTRS)

The axial forces developed on a pump impeller shroud surfaces are analyzed using a bulk-flow model of the leakage path between the impeller and the housing. Shear stresses at the impeller and the housing surfaces are modeled according to Hirs's turbulent lubrication model. The calculated results yield predictions of resonance peaks of the fluid within the annulus formed by the impeller shroud and housing. Numerical results are presented for a double-suction single-stage pump, showing that the direct stiffness of the perturbed impeller shroud forces is negligible; the forces become important only for pumps with very low axial natural frequencies in comparison to the running speed.

Childs, D. W.

1991-01-01

29

Characterization of a centrifugal pump impeller under two-phase flow conditions  

Microsoft Academic Search

Multiphase pumping is an area of primary interest, particularly for the petroleum industry, where fair amount of gas can be found in oil wells production. This study presents the results of numerical simulations carried out in a centrifugal pump impeller of an Electrical Submersible Pump (Ns=2063) conveying an air–water mixture. The results include the impeller head and the relative flow

Jose Caridad; Miguel Asuaje; Frank Kenyery; Andrés Tremante; Orlando Aguillón

2008-01-01

30

Erosion predictions of stock pump impellers based on liquid-solid two-phase fluid simulations  

NASA Astrophysics Data System (ADS)

Stock pumps cost 25 percent of total power consumption in a modern paper mill. Owing to the severe erosion of pump casing and impeller during operation, stock pump often results in efficiency drop and rising power consumption. A favourable prediction of the impeller wearing character can effective guide optimization design of stock pump impeller. Thereby it can reduce impeller wear and extend stock pump performance life. We simulated the three-dimensional unsteady solid-liquid two-phase flow characteristic in the hydraulic channel of a low specific speed stock pump with open and three blades impeller. The standard k- ? turbulent model and the pseudo-fluid model were adopted in simulation. Clearance between covers and impeller is taken into consideration in modelling, and pulp is simplified into mixtures of solid particles and water. The Finnie prediction model is applied to predict impeller erosion character. The simulation results of different solid particle size are compared with practical impeller erosion character, and the effects of solid particle size on impeller erosion character are obtained. Thus, numerical method to simulate impeller erosion characteristics of fibered pulp is investigated.

Xiao, Y. X.; Fang, B.; Zeng, C. J.; Yang, L. B.; Wang, F.; Wang, Z. W.

2013-12-01

31

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

NASA Astrophysics Data System (ADS)

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

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

2012-11-01

32

In vitro analysis of the floating mode phenomenon in the Free Impeller Gyro Pump.  

PubMed

The Free Impeller Gyro Pump was designed based on a new concept of free impeller, in which the rotational shaft and the mechanical bearings were completely eliminated from the impeller. Due to this characteristic design, a phenomenon occurred in which the impeller lifted off the bottom of the pump housing in a certain range of pumping conditions during the initial in vitro studies (floating mode). We studied this floating mode in detail using a Hall effect position sensor to monitor the impeller position. A Hall sensor signal recorded on the strip chart, which represents the distance between the impeller top and the pump ceiling, proved the existence of the floating mode. By analyzing the data in detail, it was also verified that the floating mode was composed of three subdivided phases: latent, transitional, and dominant. Furthermore, stability of the impeller rotation in the floating mode against the change of pump orientation was also exhibited in this study. These results suggests that the Free Impeller Gyro Pump should possess high antithrombogenicity, atraumatic features, no bearing wear, and stable performance when operated within the range of the floating mode. PMID:8572965

Ohara, Y; Takatani, S; Nosé, Y

1995-07-01

33

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

34

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

NASA Technical Reports Server (NTRS)

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

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

1987-01-01

35

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

Microsoft Academic Search

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

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

2010-01-01

36

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

37

Effects of meridional flow passage shape on hydraulic performance of mixed-flow pump impellers  

NASA Astrophysics Data System (ADS)

During the process of designing the mixed-flow pump impeller, the meridional flow passage shape directly affects the obtained meridional flow field, which then has an influence on the three-dimensional impeller shape. However, the meridional flow passage shape is too complicated to be described by a simple formula for now. Therefore, reasonable parameter selection for the meridional flow passage is essential to the investigation. In order to explore the effects of the meridional flow passage shape on the impeller design and the hydraulic performance of the mixed-flow pump, the hub and shroud radius ratio (HSRR) of impeller and the outlet diffusion angle (ODA) of outlet zone are selected as the meridional flow passage parameters. 25 mixed-flow pump impellers, with specific speed of 496 under the design condition, are designed with various parameter combinations. Among these impellers, one with HSRR of 1.94 and ODA of 90° is selected to carry out the model test and the obtained experimental results are used to verify accuracies of the head and the hydraulic efficiency predicted by numerical simulation. Based on SIMPLE algorithm and standard k- ? two-equation turbulence model, the three-dimensional steady incompressible Reynolds averaged Navier-Stokes equations are solved and the effects of different parameters on hydraulic performance of mixed-flow pump impellers are analyzed. The analysis results demonstrate that there are optimal values of HSRR and ODA available, so the hydraulic performance and the internal flow of mixed-flow pumps can be improved by selecting appropriate values for the meridional flow passage parameters. The research on these two parameters, HSRR and ODA, has further illustrated influences of the meridional flow passage shape on the hydraulic performance of the mixed-flow pump, and is beneficial to improving the design of the mixed-flow pump impeller.

Bing, Hao; Cao, Shuliang; Tan, Lei; Zhu, Baoshan

2013-05-01

38

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

39

Improvement of Hemolysis in a Centrifugal Blood Pump with Hydrodynamic Bearings and Semi-Open Impeller  

Microsoft Academic Search

We have developed a centrifugal blood pump with hydrodynamic bearings and semi-open impeller, and evaluated the levitation performance test and the hemolysis test. This pump is operated without any complicated control circuit and displacement-sensing module. The casing diameter is 74 mm and the height is 38 mm including flanges for volts. The weight is 251 g and the volume is

Ryo Kosaka; Takashi Yamane; Osamu Maruyama; Masahiro Nishida; Toru Yada; Sakae Saito; Shusaku Hirai

2007-01-01

40

Pulsatile Blood Flow from Impeller Pump: A Dream Has Come True  

Microsoft Academic Search

For decades many investigations have been made on producing a pulsatile blood flow with an impeller pump. It has been foiled because of excessive hemolysis. Other investigators foretold that a pulsatile centrifugal pump is impossible in the near future, without increasing the complexity of the system remarkably.The author has presevered in this study and made progress steadily. An axial pulsatile

Kun-Xi Qian

1994-01-01

41

Fracture control of H-O engine components. [titanium tin alloy fuel pump impellers  

NASA Technical Reports Server (NTRS)

An investigation was made to obtain the material characterization and fatigue crack propagation data necessary to establish the salient characteristics of a Ti-6Al-2.5Sn(ELI) alloy fuel pump impeller to be used in a cryogenic service environment. Testing variables considered were: coupon orientation, frequency, load range ratio, and temperature. Data analysis correlated crack propagation data from conventional laboratory coupons with data from a parallel sided rotating disk used to model rotor stresses. Four major design recommendations when bore regions of fuel pump impellers to be operated in cryogenic environments are to be relatively highly stressed are discussed.

Ryder, J. T.

1977-01-01

42

3D Particle image velocimetry test of inner flow in a double blade pump impeller  

NASA Astrophysics Data System (ADS)

The double blade pump is widely used in sewage treatment industry, however, the research on the internal flow characteristics of the double blade pump with particle image velocimetry (PIV) technology is very little at present. To reveal inner flow characteristics in double blade pump impeller under off-design and design conditions, inner flows in a double blade pump impeller, whose specific speed is 111, are measured under the five off-design conditions and design condition by using 3D PIV test technology. In order to ensure the accuracy of the 3D PIV test, the external trigger synchronization system which makes use of fiber optic and equivalent calibration method are applied. The 3D PIV relative velocity synthesis procedure is compiled by using Visual C++ 2005. Then absolute velocity distribution and relative velocity distribution in the double blade pump impeller are obtained. Test results show that vortex exists in each condition, but the location, size and velocity of vortex core are different. Average absolute velocity value of impeller outlet increases at first, then decreases, and then increases again with increase of flow rate. Again average relative velocity values under 0.4, 0.8, and 1.2 design condition are higher than that under 1.0 design condition, while under 0.6 and 1.4 design condition it is lower. Under low flow rate conditions, radial vectors of absolute velocities at impeller outlet and blade inlet near the pump shaft decrease with increase of flow rate, while that of relative velocities at the suction side near the pump shaft decreases. Radial vectors of absolute velocities and relative velocities change slightly under the two large flow rate conditions. The research results can be applied to instruct the hydraulic optimization design of double blade pumps.

Liu, Houlin; Wang, Kai; Yuan, Shouqi; Tan, Minggao; Wang, Yong; Ru, Weimin

2012-05-01

43

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

44

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

45

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

46

Cavitation behaviours of low specyfic speed pump impellers designed according to the "tight inlet" rule  

NASA Astrophysics Data System (ADS)

Cavitation is well-known phenomenon which occurs in the pump and may lead to the pump damage. Thus it is very important to predict cavitation parameters, during the design of the pomp elements. There are a lot of methods to estimate cavitation factor of the pump, but these methods are true only for elements designed in the "standard way" consisted algorithms, commonly known from the literature. This project shows the influence of large angles of the inlet of impeller on the pump cavitation performance. The cavitations characteristics were determined experimentally during the test. The cavitation factor was determined in analytical approaches. The common analytical formulas described in the professional literature were examined and the numerical methods were applied (with and without two — phases model). The analytical results were compared with the results from the performed experiment. In this paper, the best method to determine cavitation factor for non-standard impeller geometry was proposed.

Misiewicz, Andrzej; Skrzypacz, Janusz

2011-06-01

47

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

48

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

49

Improvement of hemolysis in a centrifugal blood pump with hydrodynamic bearings and semi-open impeller.  

PubMed

We have developed a centrifugal blood pump with hydrodynamic bearings and semi-open impeller, and evaluated the levitation performance test and the hemolysis test. This pump is operated without any complicated control circuit and displacement-sensing module. The casing diameter is 74 mm and the height is 38 mm including flanges for volts. The weight is 251 g and the volume is 159 cm3. By changing the stator relative position against the rotor, the levitation characteristics of the impeller can be adjusted. The diameter of impeller is 36 mm and the height is 25 mm. The impeller is levitated by the thrust bearing of spiral groove type and a radial bearing of herringbone type. The pump performance was evaluated through the levitation performance test and the hemolysis test. As a result, the normalized index of hemolysis (NIH) was reduced from 0.72 g/100 L to 0.024 g/100 L corresponding to the changes of the groove direction of the hydrodynamic bearing and the expansion of the bearing gap. During these studies, we confirmed that the hemolytic property was improved by balancing the fluid dynamic force and the magnetic force. PMID:18002872

Kosaka, Ryo; Yamane, Takashi; Maruyama, Osamu; Nishida, Masahiro; Yada, Toru; Saito, Sakae; Hirai, Shusaku

2007-01-01

50

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

51

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

52

Fabrication of a fully magnetic impeller for improvement of the magnetic properties of a pump with a power harvester  

NASA Astrophysics Data System (ADS)

An all-in-one wireless pump with a power generator was developed for use in biomedical applications. The developed pump is driven by an external rotating magnetic field. Thus, the performance of the system is limited by the magnetic properties of the rotor. To improve the magnetic properties of the magnetic all-in-one pump, a fully magnetic impeller was fabricated with magnetic powder (Sm2Fe17N3) because sintered magnetic materials have a lower degree of freedom for shape. The magnetic moment (M) and coercive force (Hc) of the fully magnetic impeller are 0.993 Am2 and 0.82 MA/m, respectively. We analyzed the magnetic properties of the fully magnetic impeller using simulation and experiments. In addition, we investigated the improved performance of the all-in-one pump system using the fully magnetic impeller.

Kim, Sung Hoon; Shin, Jaewon; Hashi, Shuichiro; Ishiyama, Kazushi; Ozaki, Masaru; Matsumura, Syuji

2012-04-01

53

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

54

The flow patterns within the impeller passages of a centrifugal blood pump model.  

PubMed

The effects of impeller geometry on the performance of a centrifugal blood pump model [the MSCBP design of Akamatsu and Tsukiya (The Seventh Asian Congress of Fluid Mechanics (1997), 7-10) at a 1:1 scale] have been investigated both experimentally and computationally. Four impeller designs were tested for pump hydraulic performance at the operating point (i.e. 2000 rpm), using blood analog as the working fluid. Each impeller has seven blades with different configurations including the radial straight blade and backward swept blade designs. The results show that both designs can achieve a stable head of about 100 mm Hg at the operating point. Subsequent investigations involved the visualization of the relative flow field within the impeller passages via the image de-rotation system coupled with a 2.5 W argon ion laser. Flow structures in all sectors of each impeller were examined and discussed. To further quantify the possible effects of blade geometry to thrombus formation and hemolysis, computational fluid dynamics (CFD) was used to simulate a simplified two-dimensional blade-to-blade flow analysis so as to estimate the shear stress levels. The results indicate that the stress levels found within the blade passages are generally below the threshold level of 150 N/m(2) for extensive erythrocyte damage to occur. There are some localized regions near the leading edge of the blades where the stress levels are 60% above the threshold level. However, given such a short residence time for the fluid particles to go through these high shear stress regions, their effects appear to be insignificant. PMID:11086249

Yu, S C; Ng, B T; Chan, W K; Chua, L P

2000-07-01

55

PIV Measurements and CFD Computations of Secondary Flow in a Centrifugal Pump Impeller  

Microsoft Academic Search

Two-dimensional particle image velocimetry measurements and three-dimensional computational fluid dynamics (CFD) analyses have been performed on the steady velocity field inside the shrouded impeller of a low specific-speed centrifugal pump operating with a vaneless diffuser. Flow rates ranging from 80% to 120% of the design flow rate are considered in detail. It is observed from the velocity measurements that secondary

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

2010-01-01

56

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

PubMed

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

Kelly; Humphrey

1998-03-01

57

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

NASA Technical Reports Server (NTRS)

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

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

1992-01-01

58

Rapid manufacturing techniques in the development of an axial blood pump impeller.  

PubMed

This paper presents a comparison of manufacturing techniques used in the development of an axial blood pump impeller. In this development process the impeller was designed and its performance was evaluated with the aid of computational fluid dynamics (CFD). Prototypes of those designs where the CFD results show promise were needed in sufficient quantities at a low cost for experimental validation of the CFD results. As the impeller is less than 16 mm in diameter with a maximum blade thickness of about 1.5 mm, innovative manufacturing techniques are explored in this paper to determine the best process for quick fabrication of prototypes that are dimensionally accurate, structurally robust and low in cost. Four rapid prototyping techniques were explored. The completed parts were compared on the basis of manufacturing time, quality and strength of parts obtained, manufacturing cost and also in vitro performances. Based on these studies, it was concluded that selective laser sintering (SLS) is the most appropriate method for the quick production of prototype parts for evaluation of pump performance. PMID:14702984

Chan, W K; Wong, Y W; Chua, C K; Lee, C W; Feng, C

2003-01-01

59

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

PubMed

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

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

2012-01-01

60

Evaluation of hydraulic radial forces on the impeller by the volute in a centrifugal rotary blood pump.  

PubMed

In many state-of-the-art rotary blood pumps for long-term ventricular assistance, the impeller is suspended within the casing by magnetic or hydrodynamic means. For the design of such suspension systems, profound knowledge of the acting forces on the impeller is crucial. Hydrodynamic bearings running at low clearance gaps can yield increased blood damage and magnetic bearings counteracting high forces consume excessive power. Most current rotary blood pump devices with contactless bearings are centrifugal pumps that incorporate a radial diffuser volute where hydraulic forces on the impeller develop. The yielding radial forces are highly dependent on impeller design, operating point and volute design. There are three basic types of volute design--singular, circular, and double volute. In this study, the hydraulic radial forces on the impeller created by the volute in an investigational centrifugal blood pump are evaluated and discussed with regard to the choice of contactless suspension systems. Each volute type was tested experimentally in a centrifugal pump test setup at various rotational speeds and flow rates. For the pump's design point at 5 L/min and 2500 rpm, the single volute had the lowest radial force (?0 N), the circular volute yielded the highest force (?2 N), and the double volute possessed a force of approx. 0.5 N. Results of radial force magnitude and direction were obtained and compared with a previously performed computational fluid dynamics (CFD) study. PMID:21843297

Boehning, Fiete; Timms, Daniel L; Amaral, Felipe; Oliveira, Leonardo; Graefe, Roland; Hsu, Po-Lin; Schmitz-Rode, Thomas; Steinseifer, Ulrich

2011-08-01

61

Computational modelling and evaluation of cardiovascular response under pulsatile impeller pump support  

PubMed Central

This study presents a numerical simulation of cardiovascular response in the heart failure condition under the support of a Berlin Heart INCOR impeller pump-type ventricular assist device (VAD). The model is implemented using the CellML modelling language. To investigate the potential of using the Berlin Heart INCOR impeller pump to produce physiologically meaningful arterial pulse pressure within the various physiological constraints, a series of VAD-assisted cardiovascular cases are studied, in which the pulsation ratio and the phase shift of the VAD motion profile are systematically changed to observe the cardiovascular responses in each of the studied cases. An optimization process is proposed, including the introduction of a cost function to balance the importance of the characteristic cardiovascular variables. Based on this cost function it is found that a pulsation ratio of 0.35 combined with a phase shift of 200° produces the optimal cardiovascular response, giving rise to a maximal arterial pulse pressure of 12.6 mm Hg without inducing regurgitant pump flow while keeping other characteristic cardiovascular variables within appropriate physiological ranges.

Shi, Yubing; Brown, Alistair G.; Lawford, Patricia V.; Arndt, Andreas; Nuesser, Peter; Hose, D. Rodney

2011-01-01

62

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

NASA Technical Reports Server (NTRS)

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

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

1990-01-01

63

A cost-effective extracorporeal magnetically-levitated centrifugal blood pump employing a disposable magnet-free impeller.  

PubMed

In the field of rotary blood pumps, contactless support of the impeller by a magnetic bearing has been identified as a promising method to reduce blood damage and enhance durability. The authors developed a two-degrees-of-freedom radial controlled magnetic bearing system without a permanent magnet in the impeller in order that a low-cost disposable pump-head for an extracorporeal centrifugal blood pump could be manufactured more easily. Stable levitation and contactless rotation of the 'magnet-free' impeller were realized for a prototype blood-pump that made use of this magnetic bearing. The run-out of the impeller position at between 1000 r/min and 3000 r/min was less than 40 microm in the radial-controlled directions. The total power consumption of the magnetic bearing was less than 1 W at the same rotational speeds. When the pump was operated, a flow rate of 5 l/min against a head pressure of 78.66 kPa was achieved at a rotational speed of 4000 r/min, which is sufficient for extracorporeal circulation support. The proposed technology offers the advantage of low-cost mass production of disposable pump heads. PMID:22320054

Hijikata, W; Mamiya, T; Shinshi, T; Takatani, S

2011-12-01

64

Numerical study of 3-D inducer and impeller for pump model development  

NASA Technical Reports Server (NTRS)

Current design of high-performance turbopumps for rocket engines requires effective and robust analytical tools to provide design information in a productive manner. The main goal of this study is to develop a robust and effective CFD pump model for general turbopump design and analysis applications. A finite difference Navier-Stokes flow solver, FDNS, which includes an extended k-epsilon turbulence model and appropriate moving zonal interface boundary conditions, was developed to analyze turbulent flows in turbomachinery devices. In the present study, two key components of the turbopump, the inducer and impeller, were investigated by the proposed pump model, and the numerical results were benchmarked by the experimental data provided by Rocketdyne.

Cheng, G. C.; Chen, Y. S.; Garcia, R.; Williams, R. W.

1993-01-01

65

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

66

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

67

Study on measures to improve gas-liquid phase mixing in a multiphase pump impeller under high gas void fraction  

NASA Astrophysics Data System (ADS)

Rotodynamic multiphase pump can transport crude gas-liquid mixture produced from oil well, and is regarded as the good choice of oil-gas multiphase transportation in offshore product system, for its advantages that compact structure, large flow rate, not sensitive to solid particles in the fluid. However, it is prone to bring about gas-liquid separation within the impeller under high gas void fraction. To solve the problem, this paper presents several measures to break gas packet and inhibit gas-liquid separation, such as, depositing the short blades, opening holes at the blades where gas packets gather, using T-shaped blades, etc. Then, CFD software was used to simulate the flow fields which were added measures to inhibit gas-liquid separation. The results show that streamlines in three new impellers distribute more evenly than in original impeller, the gas-liquid two phases mixed degree was improved, and the gas-liquid separation was inhibited to some extent. However, adding the short blades and using T-blade impeller failed to improve the differential pressure of impellers. So the placement and the geometrical parameters of the measures inhibiting gas-liquid separation should be further optimized.

Zhang, J. Y.; Zhu, H. W.; Ding, K.; Qiang, R.

2012-11-01

68

Research of fluid-induced pressure fluctuation due to impeller-volute interaction in a centrifugal pump  

NASA Astrophysics Data System (ADS)

The fluid pressure fluctuation generated by unsteady flow is a very important factor to induce vibration of the centrifugal pump. The relative movement between impeller and volute generates an unsteady interaction which affects not only the overall pump performance, but is also responsible for pressure fluctuations. Pressure fluctuations interact with the volute casing or even with the circuit and give rise to dynamic effects over the mechanical parts, which are one of the most important sources of vibration and hydraulic noise. To investigate the flow characteristic in the centrifugal pump, the unsteady flow is simulated by CFD methods in this paper. Unsteady flow characteristic in the centrifugal pump is obtained considering the impeller-volute interaction in the whole flow field. Based on the unsteady flow simulation, amplitude-frequency characteristics of the pressure fluctuation in the centrifugal pump are obtained through setting up monitoring point at the impeller outlet. The research shows that the frequency component include the blade passing frequency as the main component, the multiplication of blade passing frequency, and the harmonic interference due to the unsteady flow.

Liu, Q. Z.; Yang, K.; Y Li, D.; Gong, R. Z.

2013-12-01

69

Data reduction problems using a 3-hole directional pressure probe to investigate mean flow characteristics in the vaneless gap between impeller and diffuser radial pump  

NASA Astrophysics Data System (ADS)

Among several different measurement techniques that have been already performed and presented in a radial impeller pump model including PIV, a directional pressure probe has been used to obtain mean velocity field and stagnation pressure between impeller outlet and the inlet vaned diffuser sections. These measurements are supposed to get more information not only about global pump head coefficient including vaned diffuser ones but also about impeller performances itself. Pressure probe information is affected by rotor-stator interactions and impeller rotation, and this paper presents a way to explain and correct pressure probe indications in order to achieve a better evaluation of overall impeller mean performances. The use of unsteady RANS calculation results is found to be a useful way to perform better data reduction analysis for this purpose.

Cherdieu, P.; Dupont, P.; Bayeul-Lainé, A. C.; Dazin, A.; Bois, G.

2013-12-01

70

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

NASA Technical Reports Server (NTRS)

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

Childs, D. W.

1991-01-01

71

Improvement of hemocompatibility in centrifugal blood pump with hydrodynamic bearings and semi-open impeller: in vitro evaluation.  

PubMed

We have developed a noncontact-type centrifugal blood pump with hydrodynamic bearings and a semi-open impeller for mechanical circulatory assist. The impeller is levitated by an original spiral-groove thrust bearing and a herringbone-groove journal bearing, without any additional displacement-sensing module or additional complex control circuits. The pump was improved by optimizing the groove direction of the spiral-groove thrust bearing and the pull-up magnetic force between the rotor magnet and the stator coil against the impeller. To evaluate hemocompatibility, we conducted a levitation performance test and in vitro hemocompatibility tests by means of a mock-up circulation loop. In the hemolysis test, the normalized index of hemolysis was reduced from 0.721 to 0.0335 g/100 L corresponding to an expansion of the bearing gap from 1.1 to 56.1 microm. In the in vitro antithrombogenic test, blood pumps with a wide thrust bearing gap were effective in preventing thrombus formation. Through in vitro evaluation tests, we confirmed that hemocompatibility was improved by balancing the hydrodynamic fluid dynamics and magnetic forces. PMID:19681836

Kosaka, Ryo; Maruyama, Osamu; Nishida, Masahiro; Yada, Toru; Saito, Sakae; Hirai, Shusaku; Yamane, Takashi

2009-10-01

72

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

73

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

74

Suppression of secondary flows in a mixed-flow pump impeller by application of three-dimensional inverse design method. Part 2: Experimental validation  

SciTech Connect

In Part 1 of this paper, a mixed-flow pump impeller was designed by a fully three-dimensional inverse design method, aimed at suppressing the secondary flows on the blade suction surface. In this part, the internal flow fields of the impeller are investigated experimentally, using flow visualization and phase-locked measurements of the impeller exit flow, in order to validate the effects of secondary flow suppression. The flow fields are compared with those of a conventional impeller, and it is confirmed that the secondary flows on the blade suction surface are well suppressed and the uniformity of the exit flow fields is improved substantially, in both circumferential and spanwise directions. The effects of tip clearance and the number of blades for the inverse designed impeller are also investigated experimentally and numerically.

Goto, A.; Takemura, T. [Ebara Research Co., Ltd., Fujisawa (Japan); Zangeneh, M. [University College of London (United Kingdom). Dept. of Mechanical Engineering

1996-07-01

75

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

76

Experimental study on a centrifugal pump with an open impeller during startup period  

NASA Astrophysics Data System (ADS)

Transient performance of fluid machinery during transient operating periods, such as startup and stopping, has been drawn more attentions recently due to the growing engineering needs. In this paper, the transient behavior of a prototype centrifugal pump with an open impeller during rapid startup period is studied experimentally. The variations of the rotational speed, flow rate, head, and shaft power during rapid startup period are recorded in experiments at different discharge valve openings. In addition, the non-dimensional flow rate and head are also used to analyze the transient behavior. The research result shows that the rise characteristic of the rotational speed is not basically changed by working points, while mainly depends on the startup characteristics of the driving motor. Compared with the rapid rise of the rotational speed, the flow rate rises slowly in the initial stage of startup. Moreover, the flow rate lags behind the rotational speed to rise to final stable value, and the delay becomes more severe with the increase of the discharge valve opening. The shaft power impact phenomenon generally exists in the process of startup. The non-dimensional analysis shows that the non-dimensional head is very high at the very beginning of startup, and quickly falls to the minimum, then gradually rises to final stable value, while the non-dimensional flow rate always shows the rise tendency during whole startup period. In conclusion, it is found from the non-dimensional results that the quasi-steady analysis is unable to accurately assess the transient flow during startup period.

Zhang, Yuliang; Zhu, Zuchao; Jin, Yingzi; Cui, Baoling; Li, Yi; Dou, Huashu

2013-02-01

77

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

78

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

79

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

NASA Astrophysics Data System (ADS)

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.

Baskharone, Erian A.

1993-09-01

80

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

81

Impellers of low specific speed centrifugal pump based on the draughting technology  

Microsoft Academic Search

The authors analyzed the reasons of low efficiency under different operation condition based on the performance test and CFD numerical simulation approach. And the analysis focuses on the relationship between pump efficiency and inner flow characteristics. In order to improve the internal flow and increase efficiency of the pump, some draughting methods of improving the internal flow structure have been

C. Hongxun; L. Weiwei; J. Wen; W. Peiru

2010-01-01

82

Swimming and pumping of rigid helical bodies in viscous fluids  

NASA Astrophysics Data System (ADS)

Rotating helical bodies of arbitrary cross-sectional profile and infinite length are explored as they swim through or transport a viscous fluid. The Stokes equations are studied in a helical coordinate system, and closed form analytical expressions for the force-free swimming speed and torque are derived in the asymptotic regime of nearly cylindrical bodies. High-order accurate expressions for the velocity field and swimming speed are derived for helical bodies of finite pitch angle through a double series expansion. The analytical predictions match well with the results of full numerical simulations, and accurately predict the optimal pitch angle for a given cross-sectional profile. This work may improve the modeling and design of helical structures used in microfluidic manipulation, synthetic microswimmer engineering, and the transport and mixing of viscous fluids.

Li, Lei; Spagnolie, Saverio E.

2014-04-01

83

Design of a high-pressure circulating pump for viscous liquids.  

PubMed

The design of a reciprocating dual action piston pump capable of circulating viscous fluids at pressures of up to 34 MPa (5000 psi) and temperatures up to 80 degrees C is described. The piston of this pump is driven by a pair of solenoids energized alternatively by a 12 V direct current power supply controlled by an electronic controller facilitating continuously adjustable flow rates. The body of this seal-less pump is constructed using off-the-shelf parts eliminating the need for custom made parts. Both the electronic controller and the pump can be assembled relatively easily. Pump performance has been evaluated at room temperature (22 degrees C) and atmospheric pressure using liquids with low and moderately high viscosities, such as ethanol and corn oil, respectively. At ambient conditions, the pump delivered continuous flow of ethanol and corn oil at a flow rate of up to 170 and 17 cm3/min, respectively. For pumping viscous fluids comparable to corn oil, an optimum reciprocation frequency was ascertained to maximize flow rate. For low viscosity liquids such as ethanol, a linear relationship between the flow rate and reciprocation frequency was determined up to the maximum reciprocation frequency of the pump. Since its fabrication, the pump has been used in our laboratory for circulating triglycerides in contact with supercritical carbon dioxide at pressures of up to 25 MPa (3600 psi) and temperatures up to 70 degrees C on a daily basis for a total of more than 1500 h of operation functioning trouble free. PMID:19655978

Seifried, Bernhard; Temelli, Feral

2009-07-01

84

Design of a high-pressure circulating pump for viscous liquids  

NASA Astrophysics Data System (ADS)

The design of a reciprocating dual action piston pump capable of circulating viscous fluids at pressures of up to 34 MPa (5000 psi) and temperatures up to 80 °C is described. The piston of this pump is driven by a pair of solenoids energized alternatively by a 12 V direct current power supply controlled by an electronic controller facilitating continuously adjustable flow rates. The body of this seal-less pump is constructed using off-the-shelf parts eliminating the need for custom made parts. Both the electronic controller and the pump can be assembled relatively easily. Pump performance has been evaluated at room temperature (22 °C) and atmospheric pressure using liquids with low and moderately high viscosities, such as ethanol and corn oil, respectively. At ambient conditions, the pump delivered continuous flow of ethanol and corn oil at a flow rate of up to 170 and 17 cm3/min, respectively. For pumping viscous fluids comparable to corn oil, an optimum reciprocation frequency was ascertained to maximize flow rate. For low viscosity liquids such as ethanol, a linear relationship between the flow rate and reciprocation frequency was determined up to the maximum reciprocation frequency of the pump. Since its fabrication, the pump has been used in our laboratory for circulating triglycerides in contact with supercritical carbon dioxide at pressures of up to 25 MPa (3600 psi) and temperatures up to 70 °C on a daily basis for a total of more than 1500 h of operation functioning trouble free.

Seifried, Bernhard; Temelli, Feral

2009-07-01

85

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

86

Investigations on the flow field in an unshrouded pump impeller geometry  

NASA Astrophysics Data System (ADS)

Transient CFD simulations are performed to investigate the flow behaviour inside an unshrouded pump using the SAS method. Two blade designs are compared at two different tip clearances and the results are validated by measurements. The detected vortex structure is visualized by the normalized helicity, further discussed regarding its development and behaviour and finally implicated to the efficiency of the two different blade designs.

Sieber, Sten; Fröhlig, Friedrich; Caglar, Saban; Gabi, Martin

2012-04-01

87

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

NASA Technical Reports Server (NTRS)

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.

1993-01-01

88

Waterjet Impeller  

NASA Technical Reports Server (NTRS)

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

1996-01-01

89

Unshrouded Impeller Technology Development Status  

NASA Technical Reports Server (NTRS)

To increase payload and decrease the cost of future Reusable Launch Vehicles (RLVs), engineers at NASA/MSFC and Boeing, Rocketdyne are developing unshrouded impeller technology for application to rocket turbopumps. An unshrouded two-stage high-pressure fuel pump is being developed to meet the performance objectives of a three-stage shrouded pump. The new pump will have reduced manufacturing costs and pump weight. The lower pump weight will allow for increased payload.

Droege, Alan R.; Williams, Robert W.; Garcia, Roberto

2000-01-01

90

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

91

Development and Validation of High Performance Unshrouded Centrifugal Impeller.  

National Technical Information Service (NTIS)

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 i...

W. C. Chen M. Williams J. K. Paris G. H. Prueger R. Williams

2001-01-01

92

Waterjet Impeller  

NASA Technical Reports Server (NTRS)

North American Marine Jet (NAMJ), Inc. received assistance from Marshall Space Flight Center engineers in the Computational Fluid Dynamics (CFD) branch of the Structure and Dynamics Laboratory in improving the proposed design of a new impeller for their jet-propulsion systems. Marshall used advanced CFD techniques, which included creating a three-dimensional computer model of the impeller for analysis. With Marshall input, the company modified the design, then Marshall used a computer model to make a solid polycarbonate model. The rapid prototyping allowed the company to avoid many time- consuming and costly steps in creating the impeller model. NAMJ is now able to compete with Pacific-area and European manufacturers who have traditionally dominated the market.

1996-01-01

93

Three-dimensional calculation of air-water two-phase flow in centrifugal pump impeller based on a bubbly flow model  

SciTech Connect

To predict the behavior of gas-liquid two-phase flows in a centrifugal pump impeller, a three-dimensional numerical method is proposed on the basis of a bubbly flow model. Under the assumption of homogeneous bubbly flow entraining fine bubbles, the equation of motion of the mixture is represented by that of liquid-phase and the liquid velocity is expressed as a potential for a quasi-harmonic equation. This equation is solved with a finite element method to obtain the velocities, and the equation of motion of an air bubble is integrated numerically in the flow field to obtain the void fraction. These calculations are iterated to obtain a converged solution. The method has been applied to a radial-flow pump, and the results obtained have been confirmed by experiments within the range of bubbly flow regime.

Minemura, Kiyoshi; Uchiyama, Tomomi [Nagoya Univ. (Japan). School of Informatics and Sciences

1993-12-01

94

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

95

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

NASA Astrophysics Data System (ADS)

The methods of nondestructive testing (NDT) are generally ultrasonic, neutron, eddy-current and X-rays, NDT by using X-rays, in particular, is the most useful inspection technique having high resolution. We can especially evaluate corroded pipes of petrochemical complex, nuclear and thermal-power plants by the high energy X-ray NDT system. We develop a portable X-ray NDT system with X-band linac and magnetron. This system can generate a 950 keV electron beam. We are able to get X-ray images of samples with 1 mm spatial resolution. This system has application to real time impeller inspection because linac based X-ray sources are able to generate pulsed X-rays. So, we can inspect the rotating impeller if the X-ray pulse rate is synchronized with the impeller rotation rate. This system has application in condition based maintenance (CBM) of nuclear plants, for example. However, 950 keV X-ray source can only be used for thin tubes with 20 mm thickness. We have started design of a 3.95 MeV X-band linac for broader X-ray NDT application. We think that this X-ray NDT system will be useful for corrosion wastage and cracking in thicker tubes at nuclear plants and impeller of larger pumps. This system consists of X-band linac, thermionic cathode electron gun, magnetron and waveguide components. For achieving higher electric fields the 3.95 MeV X-band linac structure has the side-coupled acceleration structure. This structure has more efficient acceleration than the 950 keV linac with alternating periodic structure (APS). We adopt a 1.3 MW magnetron for the RF source. This accelerator system is about 30 cm long. The beam current is about 150 mA, and X-ray dose rate is 10 Gyat1 m/500 pps. In this paper, the detail of the whole system concept and the electromagnetic field of designed linac structure will be reported.

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

2009-03-01

96

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

97

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

98

Dealloying of a Nickel–Aluminum Bronze Impeller  

Microsoft Academic Search

A brackish water pump impeller was replaced after 4 years of service, while its predecessor lasted over 40 years. The subsequent\\u000a failure investigation determined that the nickel–aluminum bronze (NAB) impeller was not properly heat treated, which made\\u000a the impeller susceptible to aluminum dealloying. The dealloying corrosion was exacerbated by erosion, because the pump was\\u000a slightly oversized. This investigation recommended proper heat

Albert M. Olszewski

2008-01-01

99

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

SciTech Connect

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

Pawel, Steven J [ORNL

2007-03-01

100

Turbulent flow and pressure fluctuation prediction of the impeller in an axial-flow pump based on LES  

NASA Astrophysics Data System (ADS)

The Large Eddy Simulation method with sliding mesh technique has been used for analyzing the unsteady flow in an axial-flow pump at five different flow rates. The tip leakage flow in the tip-gap region and the pressure pulsations on the blade surface were examined. The results indicate that the agreement between predicted pump performance and experimental data was reasonably good. The dominate tip-leakage vortex(TLV) extended to the pressure side of the neighboring blade for all five investigated flow rates. As the flow rate increases from 0.7Qd to 1.2Qd, the angle between the dominate TLV and the blade reduced from 20 deg to 14 deg. The results also showed that the amplitude of pressure fluctuation on the near-tip zone of the blade surface increases as the flow rate farer from the design flow rate, especially on the pressure side of the blade. At the 0.7Qd operation condition, the pressure fluctuation amplitude of the monitoring point PP3 (at the near-tip zone on the pressure side of the blade close to the blade leading edge) was 8.5 times of the one at design flow rate, and the high-frequency(18fr) pulsation occurred due to tip leakage vortex. When the flow rate was more than 1.0Qd, the pressure fluctuations of PP3 was dominated by the rotation frequency(fr).

Shen, J. F.; Li, Y. J.; Liu, Z. Q.; Tang, X. L.

2013-12-01

101

Creating A Data Base For Design Of An Impeller  

NASA Technical Reports Server (NTRS)

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

Prueger, George H.; Chen, Wei-Chung

1993-01-01

102

The influence of tip clearance on performance and internal flow condition of fluid food pump using low viscous fluid  

NASA Astrophysics Data System (ADS)

Fluid machines for fluid food have been used in wide variety of fields i.e. transportation, the filling, and for the improvement of quality of fluid foods. However, flow conditions of it are quite complicated because fluid foods are different from water. Therefore, design methods based on internal flow conditions have not been conducted. In this research, turbo-pumps having a small number of blades were used to decrease shear loss and keep wide flow passage. The influence of the tip clearance was investigated by the numerical analysis using the model with and without the tip clearance. In this paper, the influence of tip clearance on performances and internal flow conditions of turbo-pump using low viscous fluid were clarified by experimental and numerical analysis results. In addition, design methods based on the internal flow were considered. Further, the influences of viscosity on the performance characteristic and internal flow were investigated.

Kubo, S.; Ishioka, T.; Fukutomi, J.; Shigemitsu, T.

2012-11-01

103

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

104

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

105

Computer Program Aids Design Of Impeller Blades  

NASA Technical Reports Server (NTRS)

Impeller blades for centrifugal turbopumps designed quickly with help of computer program. Generates blade contours and continually subjects them to evaluation. Checks physical parameters to ensure they are compatible with required performance and recycles design if criteria not met. Program written for centrifugal turbomachinery, also adapted to such axial pump components as inducer blades and stator vanes.

Chen, Wei-Chung; Galazin, John V.

1992-01-01

106

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.

Qian, Kun-xi

2007-01-01

107

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

108

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

109

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

110

Rotary blood pump  

Microsoft Academic Search

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

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

1993-01-01

111

Investigation of the HPFTP first stage impeller crack  

NASA Technical Reports Server (NTRS)

The occurrence of a crack in the HPFTP first stage impeller of pump 2608 R2 during test 750-245 prompted this analysis to examine possible causes of the failure. Preliminary analysis, using an existing NASTRAN model of the impeller, showed a deficiency in the model's ability to reliably calculate stress in the area of concern (outboard edge of the impeller shroud). A new NASTRAN model was constructed to better define the stress state in the area of crack initiations. Static stress analysis and normal models analysis were performed on the new model. Results are presented.

1984-01-01

112

Steady and Unsteady Simulations of the Flow in an Impeller/Diffuser Stage  

NASA Technical Reports Server (NTRS)

SLI engine designs will require pumps to throttle over a wide flow range while maintaining high performance. Unsteadiness generated by impeller/diffuser interaction is one of the major factors affecting off-design performance. Initial unsteady simulations are completed for impeller/diffuser stage. The Corsair simulations will continue across a wide flow range and for inducer/impeller/diffuser combinations. Results of unsteady simulations are being used to guide and explore new designs.

Canabal, Francisco; Dorney, Daniel J.; Garcia, Roberto; Turner, James E. (Technical Monitor)

2002-01-01

113

Comparisons of the relative effect of tip clearance on centrifugal impellers  

Microsoft Academic Search

The relative effect of tip clearance losses on the stage performance of centrifugal impellers was investigated using five centrifugal pump impellers with specific speeds of 0.33, 0.57, 0.83, 1.23, and 1.51. The pressure, flow rate, rotational speed, torque, and temperature of the impellers were measured and their geometrical characteristics were studied. It is observed that the relationships between developed head

A. Engeda; M. Rautenberg

1987-01-01

114

Design and Performance Analysis of Centrifugal Pump  

Microsoft Academic Search

This paper deals with the design and performance analysis of centrifugal pump. In this paper, centrifugal pump is analyzed by using a single-stage end suction centrifugal pump. Two main components of a centrifugal pump are the impeller and the casing. The impeller is a rotating component and the casing is a stationary component. In centrifugal pump, water enters axially through

Khin Cho Thin; Mya Mya Khaing; Khin Maung Aye

2008-01-01

115

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

116

Specific speed and efficiency of centrifugal impellers  

Microsoft Academic Search

Analysis of the test performance of centrifugal impellers showing a satisfactory correlation of impeller polytropic efficiency vs specific speed based on average impeller density is presented. The use of polytropic efficiency and speed reduces the impeller flow path to an equivalent incompressible frictional path; examination of test impeller efficiency levels and of internal losses indicates that the majority of the

C. Rodgers

1979-01-01

117

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

118

The influence of impeller type in pilot scale xanthan fermentations  

PubMed

The rheological complexity of Xanthan fermentations presents an interesting problem from a mixing viewpoint, because the phenomena of poor bulk blending and low oxygen mass transfer rates inherent in highly viscous fermentations (and their consequences) can be systematically investigated, even at the pilot plant scale. This study in a 150 L fermentor compares the physical and biological performance of four pairs of impellers: a standard Rushton turbine, a large diameter Rushton turbine, a Prochem Maxflo T, and a Scaba 6SRGT. Accurate in-fermentor power measurements, essential for the comparison of impellers in relation to operating costs are also reported. It is demonstrated that the agitator performance in Xanthan fermentations is very specific and the choice of which impeller to use in bioreactors to obtain enhanced performance is dependant on the applied criterion. None of the criterion favored the use of the standard Rushton turbine, therefore suggesting that there are strong grounds for retrofitting these impellers with either large diameter impellers of similar design or with novel agitators. In addition, fluid dynamic modeling of cavern formation has clearly highlighted the importance of a well mixed and oxygenated region for providing the capacity for high microbial oxygen uptake rates which govern Xanthan productivity and quality. Copyright 1998 John Wiley & Sons, Inc. PMID:10099183

Amanullah; Serrano-Carreon; Castro; Galindo; Nienow

1998-01-01

119

A novel impeller TAH using magnetic bearings for load reduction.  

PubMed

A novel impeller TAH (total artificial heart), i.e. bi-ventricular assist impeller pumps, has been developed. The device consists of a rotor with motor magnets and two impellers, a stator with motor coil and iron core, and two pump housings. In both sides of the rotor magnets, as well as the stator coil core, a pair of magnetic bearings was devised to partly counteract the attractive forces between the rotor magnets and the stator coil core. This means the magnetic bearings are used for load reduction. On hydrodynamic testing, the two pumps both produced a flow rate as high as 6 l min(-1) and the left pump had a pressure head of 150 mm Hg, and that of the right pump was 50 mm Hg. The highest efficiency of the device, including the motor, the two pumps and the controller, reached 14.7%. The device, weighing 250 g, had a length of 80 mm and a diameter of 40 mm at its largest point. Currently in the world, this is a unique TAH, which is electrically powered and driven by a single motor and has only one moving part, can produce either pulsatile or non-pulsatile flow, both pumps eject flow synchronistically by pulsatile mode, and the volume equilibrium of the two pumps can be achieved automatically without the need for control. PMID:12487713

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

2002-01-01

120

Rotary blood pump  

NASA Technical Reports Server (NTRS)

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

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

1999-01-01

121

CFD Parametric Study of 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 Finite Difference Navier-Stokes flow solver, FDNS, which includes the extended k-epsilon turbulence model and appropriate moving interface boundary conditions, was developed to analyze turbulent flows in turbomachinery devices. A second-order central difference scheme plus adaptive dissipation terms was employed in the FDNS code, along with a predictor plus multi-corrector pressure-based solution procedure. The multi-zone, multi-block capability allows the FDNS code to efficiently solve flow fields with complicated geometry. The FDNS code has been benchmarked by analyzing the pump consortium inducer, and it provided satisfactory results. In the present study, a CFD parametric study of the pump consortium impeller was conducted using the FDNS code. The pump consortium impeller, with partial blades, is a new design concept of the advanced rocket engines. The parametric study was to analyze the baseline design of the consortium impeller and its modification which utilizes TANDEM blades. In the present study, the TANDEM blade configuration of the consortium impeller considers cut full blades for about one quarter chord length from the leading edge and clocks the leading edge portion with an angle of 7.5 or 22.5 degrees. The purpose of the present study is to investigate the effect and trend of the TANDEM blade modification and provide the result as a design guideline. A 3-D flow analysis, with a 103 x 23 x 30 mesh grid system and with the inlet flow conditions measured by Rocketdyne, was performed for the baseline consortium impeller. The numerical result shows that the mass flow rate splits through various blade passages are relatively uniform. Due to the complexity of blade geometries, the TANDEM blade configurations were analyzed with the multi-zone grid structure. Both the 7.5 deg- and the 22.5 deg-clocking TANDEM blade cases utilized a 80K mesh system. The numerical result of two TANDEM blade modifications indicates the efficiency and the head are worse than those of the baseline case due to larger flow distortion. The gap between the TANDEM blade and the full blade allows the flow passes through and heavily loads the pressure side of the partial blade such that flow reversal occurs near the suction side of the splitter. The flow split at the exit of impeller blades is very non-uniform for TANDEM blade cases, and this will greatly induce the side load on the diffuser. Therefore, the TANDEM blade modification in the present CFD analysis does not improve the performance of the consortium impeller.

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

1993-01-01

122

Counter-Rotating Type Pump Unit (Rotational Behaviors)  

NASA Astrophysics Data System (ADS)

Turbo-pumps have weak points, such as the pumping operation becomes unstable in the rising portion of the head characteristics and/or the cavitation occurs at the low suction head. To overcome simultaneously both weak points, the authors invented the unique pump unit composed of the tandem impellers and the counter-rotating type motor with the double rotational armatures. The front and the rear impellers are driven by the inner and the outer armatures of the motor, respectively. Both impeller speeds are automatically and smartly adjusted in response to the pumping discharge. Such speeds controlled smartly contribute pretty well to suppress not only the unstable performances at the low discharge but also the cavitation at the high discharge, as verified in the previous paper. Continuously, the effects of the impeller profiles not only on the pump performances but also on the rotational behaviors are discussed in this paper. Two kinds of the blade profile, giving the lower and the higher heads, were prepared as the front and the rear impellers. The pump performances and the both impeller speeds are affected undoubtedly by not only the discharge but also the impeller profiles. The rotational speed of the front impeller is faster than the speed of the rear impeller in the wide discharge, while the tandem impellers composed of the front impeller giving the lower head and the rear impeller giving the higher head. Such behaviors are caused by making the angular momentum change through the front impeller coincide with that through the rear impeller.

Itou, Shintarou; Fujimura, Makoto; Nonoue, Syo; Kanemoto, Toshiaki

2010-06-01

123

CFD analyses for advanced pump design  

NASA Technical Reports Server (NTRS)

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.

1994-01-01

124

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

125

Comparison Between Predicted and Experimentally Measured Flow Fields at the Exit of the SSME HPFTP Impeller  

NASA Technical Reports Server (NTRS)

Validation of CFD codes is a critical first step in the process of developing CFD design capability. The MSFC Pump Technology Team has recognized the importance of validation and has thus funded several experimental programs designed to obtain CFD quality validation data. The first data set to become available is for the SSME High Pressure Fuel Turbopump Impeller. LDV Data was taken at the impeller inlet (to obtain a reliable inlet boundary condition) and three radial positions at the impeller discharge. Our CFD code, TASCflow, is used within the Propulsion and Commercial Pump industry as a tool for pump design. The objective of this work, therefore, is to further validate TASCflow for application in pump design. TASCflow was used to predict flow at the impeller discharge for flowrates of 80, 100 and 115 percent of design flow. Comparison to data has been made with encouraging results.

Bache, George

1993-01-01

126

Consider zig-zag impeller for desalination projects  

SciTech Connect

This article describes the application of a novel pump with a zig-zag impeller that is suited for vapor condensation. The pump is proposed to be used as the vapor condensation portion of a vapor desalination plant. Small scale testing is currently under way. No additional heat needs to be added to the seawater which boils by application of a vacuum to the desalting tank. The zig-zag pump then condenses the resulting pure water vapor and pumps it to a holding tank.

O'Keefe, W.

1993-10-01

127

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

128

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

129

Impeller for Water Jet Propulsion  

NASA Technical Reports Server (NTRS)

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

2004-01-01

130

Small centrifugal pumps for low thrust rockets  

NASA Technical Reports Server (NTRS)

This paper presents the results of a combined analytical and experimental investigation of low specific speed pumps for potential use as components of propellant feed systems for low thrust rocket engines. Shrouded impellers and open face impellers were tested in volute type and vaned diffuser type pumps. Full- and partial-emission diffusers and full- and partial-admission impellers were tested. Axial and radial loads, head and efficiency versus flow, and cavitation tests were conducted. Predicted performance of two pumps are compared when pumping water and liquid hydrogen. Detailed pressure loss and parasitic power values are presented for two pump configurations. Partial-emission diffusers were found to permit use of larger impeller and diffuser passages with a minimal performance penalty. Normal manufacturing tolerances were found to result in substantial power requirement variation with only a small pressure rise change. Impeller wear ring leakage was found to reduce pump pressure rise to an increasing degree as the pump flowrate was decreased.

Gulbrandsen, N. C.; Furst, R. B.; Burgess, R. M.; Scheer, D. D.

1985-01-01

131

Impeller tandem blade study with grid embedding for local grid refinement  

NASA Technical Reports Server (NTRS)

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

Bache, George

1992-01-01

132

Fluid flow in a rotating low-specific-speed centrifugal impeller passage  

Microsoft Academic Search

Results from experimental investigations of the blade passage flow in a model pump impeller of low specific speed are described. It is found that the flow inside the rotating impeller passages is well described by the flow distribution postulated by potential-flow arguments and boundary-layer considerations. Using a custom-designed two-component laser-Doppler-velocimetry flow measurement system, mounted on a frame co-rotating with an

F. C. Visser; J. J. H. Brouwers; J. B. Jonker

1999-01-01

133

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

134

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

135

Rotary blood pump  

NASA Astrophysics Data System (ADS)

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.; Akkerman, James W.; Aber, Greg S.; Vandamm, George A.; Bacak, James W.; Svejkovsky, Paul A.; Benkowski, Robert J.

1993-11-01

136

Rotary Blood Pump.  

National Technical Information Service (NTIS)

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 rad...

R. J. Bozeman J. W. Akkerman G. S. Aber G. A. Vandamm J. W. Bacak

1993-01-01

137

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

138

Streamlined Unobstructed One-Pass Axial-Flow Pump.  

National Technical Information Service (NTIS)

A blood pump has an impeller rotatably disposed and magnetically suspended within a cavity of a stator by a plurality of magnetic bearings (passive permanent and active electromagnetic) having impeller magnets on the impeller and stator magnets or coils/p...

D. B. Olsen H. G. Wood P. E. Allaire S. W. Day X. Song

2004-01-01

139

Computational Fluid Dynamics (CFD) Analysis for the Reduction of Impeller Discharge Flow Distortion  

NASA Technical Reports Server (NTRS)

The use of Computational Fluid Dynamics (CFD) in the design and analysis of high performance rocket engine pumps has increased in recent years. This increase has been aided by the activities of the Marshall Space Flight Center (MSFC) Pump Stage Technology Team (PSTT). The team's goals include assessing the accuracy and efficiency of several methodologies and then applying the appropriate methodology(s) to understand and improve the flow inside a pump. The PSTT's objectives, team membership, and past activities are discussed in Garcia1 and Garcia2. The PSTT is one of three teams that form the NASA/MSFC CFD Consortium for Applications in Propulsion Technology (McConnaughey3). The PSTT first applied CFD in the design of the baseline consortium impeller. This impeller was designed for the Space Transportation Main Engine's (STME) fuel turbopump. The STME fuel pump was designed with three impeller stages because a two-stage design was deemed to pose a high developmental risk. The PSTT used CFD to design an impeller whose performance allowed for a two-stage STME fuel pump design. The availability of this design would have lead to a reduction in parts, weight, and cost had the STME reached production. One sample of the baseline consortium impeller was manufactured and tested in a water rig. The test data showed that the impeller performance was as predicted and that a two-stage design for the STME fuel pump was possible with minimal risk. The test data also verified another CFD predicted characteristic of the design that was not desirable. The classical 'jet-wake' pattern at the impeller discharge was strengthened by two aspects of the design: by the high head coefficient necessary for the required pressure rise and by the relatively few impeller exit blades, 12, necessary to reduce manufacturing cost. This 'jet-wake pattern produces an unsteady loading on the diffuser vanes and has, in past rocket engine programs, lead to diffuser structural failure. In industrial applications, this problem is typically avoided by increasing the space between the impeller and the diffuser to allow the dissipation of this pattern and, hence, the reduction of diffuser vane unsteady loading. This approach leads to small performance losses and, more importantly in rocket engine applications, to significant increases in the pump's size and weight. This latter consideration typically makes this approach unacceptable in high performance rocket engines.

Garcia, R.; McConnaughey, P. K.; Eastland, A.

1993-01-01

140

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

141

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

NASA Technical Reports Server (NTRS)

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

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

1972-01-01

142

[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

143

Literature survey, numerical examples, and recommended design studies for main-coolant pumps. Final report. [PWR; BWR  

Microsoft Academic Search

This report presents an up-to-date literature survey, examples of calculations of seal forces or other pump properties, and recommendations for future work pertaining to primary coolant pumps and primary recirculating pumps in the nuclear power industry. Five main areas are covered: pump impeller forces, fluid annuli, bearings, seals, and rotor calculations. The main conclusion is that forces in pump impellers

P. E. Allaire; L. E. Barrett

1982-01-01

144

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

NASA Technical Reports Server (NTRS)

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

Childs, D. W.

1992-01-01

145

Wind-powered impeller-mixer  

SciTech Connect

The invention is an energy-saving means for providing turbulence as well as circulation to liquids in a controlled natural purification system for advanced waste water treatment and algae farming. The wind-powered impeller-mixers are used in the algae growing reactors of a controlled natural purification system. The invention consists of a vertical vane type windmill that turns an impeller blade to cause turbulence in waste water being treated. The impeller blade may be geared to operate from a horizontal position to a vertical position to provide circulation movement. A motor-generator hook-up is combined with windmill-impeller system so that generated energy may be stored for use in turning the impeller blade when there is no wind or not enough wind to operate the system. A clutch arrangement is used to disengage the impeller when the algae growing reactor is to be drained.

Freeman, P.A.; Thompson, W.J.

1981-09-29

146

Lidocaine Viscous  

MedlinePLUS

... is used to treat the pain of a sore or irritated mouth and throat often associated with ... procedures. Lidocaine viscous is not normally used for sore throats due to cold, flu, or infections such ...

147

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.

2013-01-01

148

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

PubMed

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

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

2013-01-01

149

Estimating Pump Blockage  

NASA Technical Reports Server (NTRS)

Blockage predicted for all components including inducers, impellers and diffusers. Pump performance predicted by semiempirical method shows excellent agreement with test results in Space Shuttle main-engine highpressure fuel turbopump. Comparisons of pump efficiency show equally good agreement of calculated values with experimental ones. Method improves current estimation methods based solely on subjective engineering judgment.

Chung, W.; Meng, S. Y.; Meng, C. Y.

1984-01-01

150

CFD Study of CFVAD3 Blood Pump  

NASA Astrophysics Data System (ADS)

A computational fluid dynamics (CFD) study has been performed of blood flow in the Continuous Flow Ventricular Assist Device, Prototype No. 3 (CFVAD3), which consists of a four blade shrouded impeller fully supported in magnetic bearings. This study focuses on the regions within the pump where return flow occurs to the pump inlet, and where potentially damaging shear stresses and flow stagnation might occur: the impeller blade passages and the narrow gap clearance regions between the impeller-rotor and pump housing. Two separate models define the spacing between the pump housing and the impeller's hub and shroud, and a third model defines the pump's impeller and curved blades. The flow fields in these regions were calculated for various operating conditions of the pump, and pump performance curves were calculated which compare well with data obtained experimentally. For all pump operating conditions, the flow rates within the gap regions were found to be directed toward the inlet of the pump, thus recirculating a portion of the impeller flow. The model will be used in future studies to determine increased pump efficiency, the risk of hemolysis due to shear stress, and to insure the washing of blood through the clearance regions to prevent thrombosis.

Wood, Houston; Anderson, Jay; Allaire, Paul; Bearnson, G.; Khanwilkar, P.

1998-11-01

151

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

152

SSME HPOTP impeller backcavity CFD analysis  

NASA Technical Reports Server (NTRS)

The ball bearings behind the Space Shuttle Main Engine (SSME) HPOTP preburner pump have a history of premature wear requiring their replacement. Extensive tests have been conducted in an attempt to identify the operating factors that contribute to the wear. It has been conjectured that the coolant inflow velocity swirl pattern can aid bearing operation by matching ball orbit speed and thus affect bearing life. However, control of the velocity distribution up to now could only be achieved by trial and error following hardware testing. Observation of hardware from recent flight and development operation led to the hypothesis that certain assemblies with more extensive grinding patterns on the backwall of the impeller for rotor balancing correlated with improved bearing wear. To analytically evaluate the effect of cavity configuration on the flowfield, 3-D computational fluid dynamics (CFD) analyses of various geometries was successfully executed using REACT3D. Height of the anti-vortex ribs on the stationary wall was varied, as was the configuration of the rotating wall, from smooth to simulations of various grindout patterns. The results obtained indicate the effects of the various geometries and provide valuable guidelines for cavity modification to optimize bearing cooling.

Hsu, W. W.; Lin, S. J.

1992-01-01

153

Use of partially shrouded impeller in a small centrifugal compressor  

NASA Astrophysics Data System (ADS)

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

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

2008-03-01

154

A Study on Internal Flow in a New Type of Sewage Pump  

NASA Astrophysics Data System (ADS)

Sewage pumps are designed with a wide flow channel by, for example, sacrificing some efficiency and reducing the number of blades, in order to prevent plugging with foreign bodies. Authors have been proposing a new type of sewage pump impeller designed to further improve pump efficiency and performance in passing foreign bodies. This sewage pump impeller has a structure in which the suction flow channel of closed type non-clog pump is wound in a helical spiral. The focus of this research was to investigate internal flow in this single blade sewage pump impeller by LDV measurement and CFD. As a result of having examined influence of impeller blade loading and volute casing, it clearly indicated the following facts. As well as influence of impeller blade middle loading and influence of the secondary flow, by increase of slip by influence of volute casing, static pressure and total pressure suddenly decrease together towards the end from impeller blade middle neighborhood.

Nishi, Yasuyuki; Matsuo, Nobuaki; Fukutomi, Junichiro

155

Pullulan fermentation using a prototype rotational reciprocating plate impeller.  

PubMed

A rotational reciprocating plate impeller prototype, designed to improve the mixing homogeneity of viscous non-Newtonian fermentation broth, has been tested in pullulan fermentations. With this new impeller, the operating levels of several factors were investigated to improve pullulan production with Aureobasidium pullulans ATCC 42023 in a 22-L bioreactor using experimental designs. Because both high molecular weight (MW) and high concentration of pullulan were desired; the exopolysaccharide (EPS) concentration and the broth viscosity were used as optimization objective functions to be maximized. A 6-run uniform design was used to investigate five factors. Under the best operating conditions among the six runs, 29.0 g L(-1) EPS was produced at 102 h. This condition was used as the starting point for further investigation on the two statistically significant factors, the pH and the agitation speed. An 8-run 3-level custom design that investigates up to second-order effects was used in the second stage. An optimal zone of operating conditions for large quantity of high MW pullulan production was identified. A concentration of 23.3 g L(-1) EPS was produced at 78 h. This is equivalent to an EPS productivity of 0.30 g L(-1) h(-1). The corresponding apparent viscosity of the broth was 0.38 Pa s at the shear rate of 10 s(-1). PMID:22940838

Lin, Yun; Thibault, Jules

2013-05-01

156

Vibration analysis of large centrifugal pump rotors  

NASA Astrophysics Data System (ADS)

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

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

2013-12-01

157

Study of Blade Clearance Effects on Centrifugal Pumps.  

National Technical Information Service (NTIS)

A program of analysis, design, fabrication, and testing has been conducted to develop and experimentally verify analytical models to predict the effects of impeller blade clearance on centrifugal pumps. The effect of tip clearance on pump efficiency, and ...

R. K. Hoshide C. E. Nielson

1972-01-01

158

Computational Flow Modelling of Dual Rushton Impeller Stirred Vessels  

Microsoft Academic Search

Flow in baffled stirred vessels involve interactions be- tween flow around rotating impeller blades and stationary baffles. When more than one impeller is used, which is quite common in practice, the flow complexity is greatly increased, especially when there is an interaction between the multiple impellers. The extent of interaction depends o n relative distances between the impellers and clearance

Vivek V. Ranade; Vaibhav R. Deshpande

1997-01-01

159

The performance of a centrifugal fan with enlarged impeller  

Microsoft Academic Search

The influence of enlarged impeller in unchanged volute on G4-73 type centrifugal fan performance is investigated in this paper. Comparisons are conducted between the fan with original impeller and two larger impellers with the increments in impeller outlet diameter of 5% and 10% respectively in the numerical and experimental investigations. The internal characteristics are obtained by the numerical simulation, which

Li Chunxi; Wang Song Ling; Jia Yakui

2011-01-01

160

Modelling and simulation of electric submersible pumps  

Microsoft Academic Search

The electric submersible pump unit consists of a pump powered by a medium-voltage three-phase induction motor. Starting the pump causes heavy dynamic stresses on the motor shaft and the mechanical connection between pump (impellers) and shaft. System models are developed to predict the electrical and mechanical conditions on starting

O. V. Thorsen; M. Dalva

1999-01-01

161

Computational fluid dynamics modeling of impeller designs for the HeartQuest left ventricular assist device.  

PubMed

To finalize the design of the next generation of the HeartQuest left ventricular assist device, a suitable impeller had to be designed and tested. The new prototype was based on calculations and test results of previous designs, but required several changes to decrease the size. For most pump designs, this is a simple matter of altering impeller geometry and rotational speed to achieve the desired pressure rise and flow rate. However, this particular pump was limited by housing geometry and the magnetic bearings that support the impeller. Without much freedom in the overall impeller size, the only parameters open to the designers were the blade profiles and the rotating speed. Rather than build several candidates and test them in a rig at enormous cost, computational models of several designs were tested and analyzed. This not only saved money, but also sped up the development time for the project. The computer models were developed in TASCflow, a computational fluid dynamics software package from AEA Technologies. This paper analyzes the data from several of the selected models, paying close attention to pumping performance and general trends from specific design changes. PMID:12296578

Curtas, Anthony R; Wood, Houston G; Allaire, Paul E; McDaniel, James C; Day, Steven W; Olsen, Don B

2002-01-01

162

On the prediction of the reverse flow onset at the centrifugal pump inlet  

Microsoft Academic Search

Several models of centrifugal pump impellers were designed and tested in order to find design criteria for minimum reverse flow capacity and wide pump operating range. Aerodynamic pressure field, meridional flow diffusion and secondary flows were assumed as prevailing factors on flow separation and reverse flow onset in impellers of low specific speed centrifugal pumps. Overall and detailed time steady

B. Schiavello; M. Sen

1980-01-01

163

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

164

Development Of A Novel Direct Motor Driven Seal-less Centrifugal Blood Pump (Baylor Gyro Pump)  

Microsoft Academic Search

In this paper, a new design concept of a direct motor driven seal-less Centrifugal blood pump is presented. A rotor of a brushless DC motor is placed in the inlet side of the centrifugal pump and is directly connected with the impeller. The rotor-impeller is contained in a seal-less pump case. A thin pipe separates the rotor and stator of

I. Sakuma; T. Sasaki; M. Shiono; S. Takatani; G. P. Noon; Y. Nose; M. E. DeBakey

1991-01-01

165

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

166

Liquid rocket propulsion impeller CFD modeling  

Microsoft Academic Search

Steady-state impeller geometric modeling and typical Navier-Stokes CFD algorithm analysis procedures are assessed using two benchmark quality impeller data sets. Two geometric modeling and grid generation software packages, ICEM-CFD and PATRAN, are considered. Results show that a significant advantage of PATRAN's open-ended architecture is the potential interaction between CFD and structural\\/thermal analysts inside the mechanical computer-aided engineering environment. However the

Mark L. Ratcliff; Mahesh M. Athavale; Matthew E. Thomas; Robert W. Williams

1993-01-01

167

Pump CFD code validation tests  

NASA Technical Reports Server (NTRS)

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

Brozowski, L. A.

1993-01-01

168

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

169

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

170

Rotary magnetic heat pump  

SciTech Connect

Magnetic heat pumps use the magneto-caloric effect to produce entropy changes necessary for heat pumping. A rotary magnetic heat pump has been analyzed and computer models have been developed. The contribution of viscous heat to the regenerator heat balance has been found to significantly restrict performance. The contribution of viscous heating is at least as important as the temperature differences required for regenerator heat transfer. Multiple magnet coils on a single rotor reduce the viscous work per field change cycle and result in greatly improved performance. Operation at 80% of Carnot efficiency with a heat pumping rate of 10 kW per kilogram of magnetic material is predicted.

Kirol, L.D.; Mills, J.I.

1984-01-01

171

Individual impeller flooding in aerated vessel stirred by multiple-Rushton impellers  

Microsoft Academic Search

The paper presents flooding detection in the dispersion of air into water in a stirred vessel equipped with a multiple-turbine impeller. All experiments were performed in a pilot-size mixing vessel using single, dual and triple Rushton turbine impellers. Deionized water and compressed air were used as a working fluid. The flooding recognition method based on resistivity probe response was applied,

Andrej Bomba?; Iztok Žun

2006-01-01

172

Orthogonal test and experimental study on fire floating pump  

NASA Astrophysics Data System (ADS)

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

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

2013-12-01

173

Pump Design  

NASA Technical Reports Server (NTRS)

A NASA handbook on a general purpose titanium alloy was used by Sundstrand Corporation in design calculation for casting titanium impellers. Information contributed substantially to improved impeller design.

1981-01-01

174

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

175

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

176

Study of blade clearance effects on centrifugal pumps  

NASA Technical Reports Server (NTRS)

A program of analysis, design, fabrication, and testing has been conducted to develop and experimentally verify analytical models to predict the effects of impeller blade clearance on centrifugal pumps. The effect of tip clearance on pump efficiency, and the relationship between the head coefficient and torque loss with tip clearance was established. Analysis were performed to determine the cost variation in design, manufacture, and test that would occur between unshrouded and shrouded impellers. An impeller, representative of typical rocket engine impellers, was modified by removing its front shroud to permit variation of its blade clearances. It was tested in water with special instrumentation to provide measurements of blade surface pressures during operation. Pump performance data were obtained from tests at various impeller tip clearances. Blade pressure data were obtained at the nominal tip clearance. Comparisons of predicted and measured data are given.

Hoshide, R. K.; Nielson, C. E.

1972-01-01

177

Experimental Investigation into the performance of the Axial-Flow-Type Waterjet according to the Variation of Impeller Tip Clearance  

Microsoft Academic Search

The tip clearance inside the duct from the tip of the impeller is very important to the performance of waterjet systems, which fact has been proven in the pump field. The tip clearance is especially important on the model scale because it is very difficult in manufacture to keep the tip clearance constant and minimally small along the inside of

Moon-Chan Kim; Ho-Hwan Chun

2007-01-01

178

Strength of Wheels of High-Pressure Hydrogen Pumps  

Microsoft Academic Search

With the example of an oxygen–hydrogen liquid-propellant rocket engine with afterburning for the launch vehicle “Énergiya,” we consider the structural strength of impellers of a hydrogen pump. It is shown that the specific strength of the structural materials of impellers in liquid hydrogen is considerably influenced by their plasticity. On the basis of the data of experiments, the admissible peripheral

A. I. Dmitrenko; V. S. Rachuk; M. A. Rudis; V. I. Kholodnyi

2000-01-01

179

Flow study on a newly developed impeller for a left ventricular assist device.  

PubMed

Nowadays, left ventricular assist devices are usually designed as high-speed, electric, rotary blood pumps. The pump drains blood from the left ventricular apex via an inlet cannula and ejects into the aortic root via an outlet conduit. To develop a high-performance pump, the present study utilizes partial differential equations to generate a surface representation of the impeller of the blood pump. Flow analysis around the impeller is performed by using the finite volume method to solve the fully incompressible three-dimensional Navier-Stokes equations along with the k-epsilon turbulence model. The numerical results highlight flow features in the end-wall region of the pump, namely the clearance leakage cross-flow, and the vortex associated with this leakage. These secondary flows induce major energy losses in the pumping device. On the test study, a test loop was proposed to measure the performance characteristics. It was shown that the design would provide a flow rate of 4.4 l/min with a pressure head of 122 mmHg. The DC motor power under these conditions was about 6 W and the rotational speed was 4500 rpm. Both the flow rate and head can satisfy the demand for the left artificial heart to work normally. PMID:14598109

Hsu, Cheung-Hwa

2003-01-01

180

Compressor Impeller Erosion Resistant Surface Treatment.  

National Technical Information Service (NTIS)

Electro-spark alloyed (ESA) surfaces were developed as an erosion barrier for Ti-6-4 impellers on shaft driven compressors (SDCs). Coatings based on tungsten carbide tantalum carbide. titanium carbide all with a cobalt matrix were evaluated for high veloc...

M. A. Riley

2000-01-01

181

Combined electrical and mechanical model of electric submersible pumps  

Microsoft Academic Search

The electric submersible pump unit consists of a pump powered by a medium-voltage three-phase induction motor. The power transmission system is integrated with the riser pipes. Starting the pump causes heavy dynamic stresses on the motor shaft and the mechanical connection between pump (impellers) and shaft. The motor and its load will generate transient torque pulsations that may be damaging

Olav Vaag Thorsen; Magnus Dalva

2001-01-01

182

Effects of Impeller-Diffuser Interaction on Centrifugal Compressor Performance  

NASA Technical Reports Server (NTRS)

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

Tan, Choon S.

2003-01-01

183

Method and apparatus for producing viscous crudes  

SciTech Connect

This patent describes an apparatus for producing viscous crudes from a producing wellbore, comprising: (a) an electrical submersible pump lift system; (b) a shroud having an inlet for reservoir fluids containing such viscous crudes, the shroud substantially surrounding the inlet to the electrical submersible pump; (c) a water conduit for conducting water from the surface to the shroud inlet; and (d) water inlet means connected to the water conduit and communicating with the crude inlet of the shroud for continuously injecting water into the crude inlet and mixing such water with reservoir fluids coming in through the crude inlet.

Thomas, D.W.; Corby, R.S

1989-05-23

184

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

185

Experimental investigation of rotor-stator interaction in a centrifugal pump with several vaned diffusers  

NASA Technical Reports Server (NTRS)

Steady and unsteady diffuser vane pressure measurements have been conducted with a two-dimensional test impeller, in an experimental investigation of rotor-stator interaction within a centrifugal pump having several vaned diffusers, under conditions of different flow coefficients and different radial gaps between the impeller blade trailing edge and the diffuser vane leading edge. The largest pressure fluctuations on the diffuser vanes and the impeller blades were found to be of the same order of magnitude as the total pressure rise across the pump. Increasing the number of diffuser vanes was found to result in a significant decrease of impeller blade pressure fluctuations.

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

1990-01-01

186

Design optimization for a shaft-less double suction mini turbo pump  

NASA Astrophysics Data System (ADS)

In order to further satisfy the operation needs for social applications, a shaft-less double suction mini turbo pump with outer impeller diameter of 24 mm and specific speed of 188 min-1·m3min-1·m has been designed. In order to simulate the three dimensional steady turbulent flow in the mini pump so as to improve the pump impeller design, RANS equations and k-? SST turbulence model are used. Based on the detailed analysis of the internal flow in the pump, six new impellers have been designed to investigate the effects of impeller parameters on the performance of the mini pump. Based on those results, the following conclusions are drawn: (1) For the double-suction shaft-less mini turbo pump, the averaged wall shear stress has very low level and the maximum hydraulic efficiency is larger than 80%. Those favourable features must be related to the symmetric suction design of the mini pump; (2) Large vane angle at the trailing edge is suitable for a mini turbo pump in many applications so as to obtain higher head and smaller impeller size. On the other hand, the impellers with ?1=90° may result in large wall shear stress at the vane leading edge at small flow rate; (3) Because the radial impeller is much convenient for manufacture and creates much larger head, it is preferable for a mini turbo pump if the wall shear stress can be controlled within the acceptable range due to further design optimization.

Zhuang, B.; Luo, X.; Zhang, Y.; Wang, X.; Xu, H.; Nishi, M.

2010-08-01

187

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

188

Centrifugal Force Based Magnetic Micro-Pump Driven by Rotating Magnetic Fields  

NASA Astrophysics Data System (ADS)

This paper presents a centrifugal force based magnetic micro-pump for the pumping of blood. Most blood pumps are driven by an electrical motor with wired control. To develop a wireless and battery-free blood pump, the proposed pump is controlled by external rotating magnetic fields with a synchronized impeller. Synchronization occurs because the rotor is divided into multi-stage impeller parts and NdFeB permanent magnet. Finally, liquid is discharged by the centrifugal force of multi-stage impeller. The proposed pump length is 30 mm long and19 mm in diameter which much smaller than currently pumps; however, its pumping ability satisfies the requirement for a blood pump. The maximum pressure is 120 mmHg and the maximum flow rate is 5000ml/min at 100 Hz. The advantage of the proposed pump is that the general mechanical problems of a normal blood pump are eliminated by the proposed driving mechanism.

Kim, S. H.; Hashi, S.; Ishiyama, K.

2011-01-01

189

Liquid rocket propulsion impeller CFD modeling  

NASA Technical Reports Server (NTRS)

Steady-state impeller geometric modeling and typical Navier-Stokes CFD algorithm analysis procedures are assessed using two benchmark quality impeller data sets. Two geometric modeling and grid generation software packages, ICEM-CFD and PATRAN, are considered. Results show that a significant advantage of PATRAN's open-ended architecture is the potential interaction between CFD and structural/thermal analysts inside the mechanical computer-aided engineering environment. However the time required to construct the inducer grid would be unacceptable in a design and engineering environment. The ICEM-CFD package is considered to be more appropriate for structural grid generation but lacks the mature link to structural/thermal analysis arena as compared to PATRAN.

Ratcliff, Mark L.; Athavale, Mahesh M.; Thomas, Matthew E.; Williams, Robert W.

1993-01-01

190

Impeller wear impact-abrasive wear test  

Microsoft Academic Search

In order to more accurately simulate wear behavior that occurs in the field (i.e., impact coupled with abrasion), an impeller-in-drum wear test has been developed. The apparatus is similar to the one first developed by Bond; however, in the apparatus used at the Albany Research Center, three paddles instead of just one are situated in the drum which can be

R. D Wilson; J. A Hawk

1999-01-01

191

Estimation of Centrifugal Pump Head in Steam-Water Two-Phase Flow  

Microsoft Academic Search

A series of two-phase pump performance tests were carried out by using three model pumps: two high head (225 m) pumps which were similar in shape but different in size, and one low head (25 m) pump. Experimental data were reduced with two-phase mixture density at exit of impeller. The results showed that pump heads for volumetric quality less than

Akihiko MINATO; Atsuo YAMANOUCHI; Tadashi NARABAYASHI

1985-01-01

192

Engineering Aspects in Blood Pump Development  

NASA Technical Reports Server (NTRS)

NASA turbomachinery computer codes assisted in the design of the Cleveland Clinic Foundation's centrifugal bladed blood pump. The codes were originally developed for the aerospace industry, but are applicable to the blood pump because of a high degree of synergy with this application. Traditional turbomachinery design criteria were used in the design of the blood pump centrifugal impeller and volute casing. The fluid dynamic performance of the blood pump is meeting the engineering design goals of flow rate and pressure rise.

Golding, Leonard; Veres, Joseph P.

1997-01-01

193

CFD Study of CFVAD3 Blood Pump  

Microsoft Academic Search

A computational fluid dynamics (CFD) study has been performed of blood flow in the Continuous Flow Ventricular Assist Device, Prototype No. 3 (CFVAD3), which consists of a four blade shrouded impeller fully supported in magnetic bearings. This study focuses on the regions within the pump where return flow occurs to the pump inlet, and where potentially damaging shear stresses and

Houston Wood; Jay Anderson; Paul Allaire; G. Bearnson; P. Khanwilkar

1998-01-01

194

Electrostatic charge generation during impeller mixing of used transformer oil  

Microsoft Academic Search

The purpose of this study was to examine the effects of varying conductivity and turbulent impeller mixing intensity on charge generation of used Shell Diala® transformer oil. The oil was mechanically agitated by a pitched six-bladed impeller in a 1.5quart fully baffled cylindrical vessel at impeller Reynolds numbers between 5?000 and 10?000. The electrical current generated from the mixing operation

John P. Wagner; Fernando Rangel Clavijo

2000-01-01

195

WATER TEST DEVELOPMENT OF THE FUEL PUMP FOR THE MSRE  

Microsoft Academic Search

A vertical centrifugal sump-type pump utilizing commercially available ; impeller and volute designs was selected to circulate the fuel salt in the Molten ; Salt Reactor Experiment (MSRE). Tests were conducted in water to determine the ; adequacy of the pump design, to assist design of the prototype fuel pump, and to ; investigate the effectiveness of xenon removal with

1962-01-01

196

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

197

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

198

Satellite Propellant Pump Research  

NASA Technical Reports Server (NTRS)

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

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

2005-01-01

199

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

200

Detection and effects of pump low-flow operation  

SciTech Connect

Operating experience and previous studies have shown that a significant cause of pump problems and failures can result from low- flow operation. Operation at low-flow rates can create unstable flows within the pump impeller and casing. This condition can result in an increased radial and axial thrust on the rotor, which in turn causes higher shaft stresses, increased shaft deflection, and potential bearing and mechanical seal problems. Two of the more serious results of low-flow pump operation are cavitation and recirculation. Cavitation is the formation and subsequent collapse of vapor bubbles in any flow that is at an ambient pressure less than the vapor pressure of the liquid medium. It is the collapse of these vapor bubbles against the metal surfaces of the impeller or casing that causes surface pitting, erosion, and deterioration. Pump recirculation more damaging than cavitation. If located at the impeller eye, recirculation damages the inlet areas of the casing. At the impeller tips, recirculation alters the outside diameter of the impeller. If recirculation occurs around impeller shrouds, it damages thrust bearings. Recirculation also erodes impellers, diffusers, and volutes and causes failure of mechanical seals and bearings. This paper reports on a utility pump failure caused by low-flow induced phenomena. ORNL is investigating the results of low-flow pump operations by evaluating the types of measurements and diagnostic techniques that are currently used by licensees to detect pump degradation. A new, enhanced application of motor current and power data analysis has been developed that uses a signal comparison methodology to produce an instability ratio indicative of normal or unstable flow conditions. Examples of this type of low-flow detection technique are presented in this paper along with a brief discussion of the various types of technologies currently being used by licensees to evaluate pump operation and determine possible degradation.

Casada, D.A.; Greene, R.H.

1993-12-01

201

Alignment and operability analysis of a vertical sodium pump  

SciTech Connect

With the objective of identifying important alignment features of pumps such as FFTF, HALLAM, EBR II, PNC, PHENIX, and CRBR, alignment of the vertical sodium pump for the Clinch River Breeder Reactor Plant (CRBRP) is investigated. The CRBRP pump includes a flexibly coupled pump shaft and motor shaft, two oil-film tilting-pad hydrodynamic radial bearings in the motor plus a vertical thrust bearing, and two sodium hydrostatic bearings straddling the double-suction centrifugal impeller in the pump.

Gupta, V.K.; Fair, C.E.

1981-01-01

202

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

203

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

204

Improved performance in viscous mycelial fermentations by agitator retrofitting.  

PubMed

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

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

1988-05-01

205

Spiral viscous fingering.  

NASA Astrophysics Data System (ADS)

When a less-viscous fluid displaces a more-viscous fluid in a radial Hele-Shaw cell, viscous fingering pattern is believed to develop in a radial direction. We performed experiments on viscous fingering in a radial Hele-Shaw cell when a polymer solution, a sodium polyacrylate (SPA) solution is used as the more-viscous fluid and the trivalent iron (Fe^3+) solution is as the less-viscous fluid. The experiment was done by varying the concentration of Fe^3+, cFe3+. We have found that viscous fingering pattern develops spirally when cFe3+ is larger than a threshold value, while the pattern develops in a radial direction for small cFe3+. We confirmed from different experiments that an instantaneous chemical reaction takes place between SPA solution and Fe^3+ solution. The chemical reaction produces precipitation and significantly reduces the viscosity of the SPA solution. The quantity of the precipitation is increased with cFe3+. We will make a discussion on the relationship between the formation of spiral viscous fingering and the chemical reaction taking place between the two fluids.

Nagatsu, Yuichiro; Hayashi, Atsushi; Kato, Yoshihito; Tada, Yutaka

2006-11-01

206

Gas-liquid dispersion with dual Rushton turbine impellers.  

PubMed

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

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

1989-08-20

207

Retrofit of CD-6 (Smith) impeller in fermentation vessels.  

PubMed

We extended prior studies on the influence of impeller type on fermentation performance to include a novel low-power-number, high-efficiency radial flow impeller, the CD-6, possessing six curved blades on a disk turbine. Dual impeller combinations of CD-6/CD-6, CD-6/Maxflo T, and CD-6/HE-3 were compared with Rushton/Rushton and Maxflo T/Maxflo T base cases. Qualitative comparisons of unaerated and aerated power draw in both water and glycerol were conducted. These suggested minimal power drops with aeration for dual CD-6 impellers and hybrids containing the CD-6 impeller design. We also examined fermentation performance for Streptomyces and Glarea secondary metabolite fermentations. A qualitative comparison of the data suggested that dual CD-6 impellers and hybrids containing the CD-6 impeller design resulted in reasonable power draws, improved mass transfer rates with airflow increases, and acceptable peak titers. These arrangements may warrant further study under a wider range of production conditions. PMID:11069009

Junker, B H; Mann, Z; Hunt, G

2000-10-01

208

Hydrojet Ducted Propulsion System: Impeller Induced Vibratory Pressures and Performance Characteristics.  

National Technical Information Service (NTIS)

A vortex-line theory developed for an impeller in a long duct was used to optimize the design of a Hydrojet impeller. A model Hydrojet with this impeller was instrumented for pressure field and impeller performance measurements. Fluctuating pressures were...

M. R. Hale D. H. Norrie

1966-01-01

209

Simulation of flows in stirred vessels agitated by dual rushton impellers using computational snapshot approach  

Microsoft Academic Search

Flow in baffled stirred vessels involves interactions between flow around rotating impeller blades and stationary baffles. When more than one impeller is used (which is quite common in practice), the flow complexity is greatly increased, especially when there is an interaction between two impellers. The extent of interaction depends on relative distances between the two impellers and clearance from the

Vaibhav R. Deshpande; Vivek V. Ranade

2003-01-01

210

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

211

Retrofit of CD6 (smith) impeller in fermentation vessels  

Microsoft Academic Search

We extended prior studies on the influence of impeller type on fermentation performance to include a novel low-power-number,\\u000a high-efficiency radial flow impeller, the CD-6, possessing six curved blades on a disk turbine. Dual impeller combinations\\u000a of CD-6\\/CD-6, CD-6\\/Maxflo T, and CD-6\\/HE-3 were compared with Rushton\\/Rushton and Maxflo T\\/Maxflo T base cases. Qualitative\\u000a comparisons of unaerated and aerated power draw in

Beth H. Junker; Zorina Mann; George Hunt

2000-01-01

212

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

213

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

214

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

215

Analysis of Viscous Micropumps and Microturbines  

NASA Astrophysics Data System (ADS)

A numerical study of the three-dimensional viscous fluid flow in a novel pump/turbine device appropriate for microscale applications is performed. The device essentially consists of a rotating or free-to-rotate cylinder eccentrically placed in a channel, and is shown to be capable of generating a net flow against an externally imposed pressure gradient, or, conversely, generating a net torque in the presence of an externally imposed bulk flow. Full Navier-Stokes, finite-element simulations are carried out to study the influence of the width and other geometric as well as dynamic parameters, and the results are compared to our previous two-dimensional numerical and physical experiments. The three-dimensional simulations indicate a gradual decrease of the bulk velocity and pump performance as the two side walls become closer providing increased viscous resistance to the flow. However, effective pumping is still observed with extremely narrow channels. The utility of the device as a microturbine is also demonstrated for the first time in the present simulations. Particularly, the angular velocity of the rotor and the viscous torque are determined when a bulk velocity is imposed.

Decourtye, David; Sen, Mihir; Gad-El-Hak, Mohamed

1997-11-01

216

Effects of Impeller-Diffuser Interaction on Centrifugal Compressor Performance.  

National Technical Information Service (NTIS)

This research program focuses on characterizing the effect of impeller-diffuser interactions in a centrifugal compressor stage on its performance using unsteady threedimensional Reynolds-averaged Navier-Stokes simulations. The computed results show that t...

C. S. Tan

2003-01-01

217

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

218

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

219

Viscous shear dampers  

SciTech Connect

In a viscous shear damper, the seismic mass is chamfered at all its corners. Thus, the clearances between the seismic mass and its casing are gaps with oppositely widening out sections separated by middle sections of smallest widths.

Zilahi-Szabo, I.

1980-10-07

220

NUMERICAL APPROACH TO THE PREDICTION OF CAVITATION IN PUMPS  

Microsoft Academic Search

MODELISATION OF THE INTERNAL FLOW The numerical method to approach the cavitation phenomena is based on the flow monitoring through pump impellers. To calculate the internal flow, the code PHOENICS is used. Through this report we try to bring out effects induced by volute on centrifugal pump's cavitations phenomena, and allow drawing up a possible prediction law about cavitation inception

Zgolli Ridha; Azouz Houcine

221

Analysis and Optimization Laminar Viscous Flow Through a Channel  

NASA Astrophysics Data System (ADS)

Optimizing of laminar viscous flow through a pipe by two dimensionless values is investigated analytically. Dimensionless entropy generation and pumping power to heat transfer rate ratio are used as basis for constant viscous and the temperature dependence on the viscosity. For this matter we calculate entropy generation and pumping power for a fully developed in a pipe subjected to constant wall temperature for either constant viscosity and the variable viscosity. The variation entropy generation increase along the pipe length for viscous fluid is drawn, either the variation summation dimensionless entropy generation and the pumping power to heat transfer rate ratio are varying the fluid inlet temperature for fixed pipe length and are varying pipe length for fixed fluid inlet temperature are drawn. For low heat transfer conditions the entropy generation due to viscosity friction becomes dominant and the dependence of viscosity with the temperature becomes essentially important to be considered.

Langeroudi, H. G.; Aghanajafi, C.

2006-12-01

222

Mixing of complex fluids with flat-bladed impellers: effect of impeller geometry and highly shear-thinning behavior  

Microsoft Academic Search

Mixing of rheological complex fluids was investigated using flat-bladed impellers as close-clearance agitators in the laminar regime. Two Newtonian and six highly shear-thinning fluids were used. The non-Newtonian fluids were adequately described by a power-law model with a flow index n between 0.1 and 0.4. Power draw analysis was used to explore the combined influence of pseudoplasticity and impeller geometry.

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

2004-01-01

223

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

NASA Astrophysics Data System (ADS)

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

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

2013-12-01

224

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

225

Centrifugal Pumps for Swimming Pools. National Sanitation Foundation Standard Number 17.  

ERIC Educational Resources Information Center

The pumps discussed herein are intended to be used for recirculating water in swimming pools, both public and private. Included are the basic components which may be a part of a pump such as the housing, strainer, impeller, valves, and such other parts as are attached or a part of the pump as supplied by the manufacturer. This standard is intended…

National Sanitation Foundation, Ann Arbor, MI. Committee for Swimming Pool Equipment Standards.

226

Flow patterns and shear stress investigation and in vitro studies of blood pump  

Microsoft Academic Search

The long-term clinical use of blood pumps is dependent on the bio-compatibility. Blood trauma especially hemolysis is closely related to the flow fields in the pumps according to the homodynamic. Computational fluid dynamics technique has been used to visualize the flow patterns and distribution of shear stress in two pumps with different impeller designs and to evaluate the hemolysis level.

Fangqun Wang; Qinlin Wu; Teng Jing; Linlin Liu; Kunxi Qian

2010-01-01

227

Numerical analysis and hemolysis prediction in an implantable aortic valve-pump  

Microsoft Academic Search

An implantable aortic valve-pump was designed. There were a central rotor and a stator in the device. The rotor was consisted of driven magnets and an impeller, the stator was consisted of a motor coil with an iron core, an inducer and a diffuser. This pump has promisingly better antithrombogenicity than other heart pumps, for neither connecting conduits nor “bypass”

Kunxi Qian; Qinlin Wu; Fangqun Wang

2010-01-01

228

Geometric Optimization for Non-Thrombogenicity of a Centrifugal Blood Pump through Flow Visualization  

Microsoft Academic Search

A monopivot centrifugal blood pump, whose impeller is supported with a pivot bearing and a passive magnetic bearing, is under development for implantable artificial heart. The hemolysis level is less than that of commercial centrifugal pumps and the pump size is as small as 160 mL in volume. To solve a problem of thrombus caused by fluid dynamics, flow visualization

Masahiro Toyoda; Masahiro Nishida; Osamu Maruyama; Takashi Yamane; Tatsuo Tsutsui; Yoshiyuki Sankai

2002-01-01

229

Fluid pumping apparatus  

DOEpatents

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

West, Phillip B. (Idaho Falls, ID)

2006-01-17

230

Computational fluid dynamic design of rocket engine pump components  

NASA Technical Reports Server (NTRS)

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

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

1992-01-01

231

Optimization of a Centrifugal Impeller Design Through CFD Analysis  

NASA Technical Reports Server (NTRS)

This paper discusses the procedure, approach and Rocketdyne CFD results for the optimization of the NASA consortium impeller design. Two different approaches have been investigated. The first one is to use a tandem blade arrangement, the main impeller blade is split into two separate rows with the second blade row offset circumferentially with respect to the first row. The second approach is to control the high losses related to secondary flows within the impeller passage. Many key parameters have been identified and each consortium team member involved will optimize a specific parameter using 3-D CFD analysis. Rocketdyne has provided a series of CFD grids for the consortium team members. SECA will complete the tandem blade study, SRA will study the effect of the splitter blade solidity change, NASA LeRC will evaluate the effect of circumferential position of the splitter blade, VPI will work on the hub to shroud blade loading distribution, NASA Ames will examine the impeller discharge leakage flow impacts and Rocketdyne will continue to work on the meridional contour and the blade leading to trailing edge work distribution. This paper will also present Rocketdyne results from the tandem blade study and from the blade loading distribution study. It is the ultimate goal of this consortium team to integrate the available CFD analysis to design an advanced technology impeller that is suitable for use in the NASA Space Transportation Main Engine (STME) fuel turbopump.

Chen, W. C.; Eastland, A. H.; Chan, D. C.; Garcia, Roberto

1993-01-01

232

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

233

Study of the Air-Water Two-Phase Centrifugal Pump by Resistivity Probe Measurement of Void Fraction (I): Measurement of Void Fraction Distribution.  

National Technical Information Service (NTIS)

The performance of a centrifugal pump when air was blown into the water flow during operation was measured. The resistivity probe method was used to measure the void fraction distribution in the impeller. Flow patterns observed in the impeller when the ai...

K. Sekoguchi

1983-01-01

234

A novel impeller configuration to improve fungal physiology performance and energy conservation for cephalosporin C production.  

PubMed

Effects of impeller configuration on fungal physiology and cephalosporin C production were investigated by an industrial strain Acremonium chrysogenum in a 12 m(3) bioreactor equipped with conventional and novel impeller configuration, respectively. The cell growth and oxygen uptake rate (OUR) profiles were little affected by the impeller configurations. However, differing impeller combinations significantly affected the morphology, which in turn influenced cephalosporin C production. Under the novel impeller configuration, the production of cephalosporin C was 10% higher and an excessive amount of dispersed arthrospores was also observed. Computational fluid dynamics (CFD) simulation further revealed that poor mass and energy exchange as well as inhomogeneous environment existed in the bioreactor equipped with conventional impeller configuration. For equivalent power dissipation, the volume oxygen transfer coefficient (K(L)a) could be enhanced by 15% compared with that of conventional impeller configuration. Power consumption was dramatically decreased by 25% by using novel impeller configuration. PMID:22835853

Yang, Yiming; Xia, Jianye; Li, Jianhua; Chu, Ju; Li, Liang; Wang, Yonghong; Zhuang, Yingping; Zhang, Siliang

2012-10-31

235

A Study on Internal Flow in a New Type of Sewage Pump  

NASA Astrophysics Data System (ADS)

Sewage pumps are designed with a wide flow channel by, for example, sacrificing some efficiency and reducing the number of blades, in order to prevent plugging with foreign bodies. Authors have been proposing a new type of sewage pump impeller designed to further improve pump efficiency and performance in passing foreign bodies. This sewage pump impeller has a structure in which the suction flow channel of closed type non-clog pump is wound in a helical spiral. The focus of this research was to investigate internal flow in this single blade sewage pump impeller. The results clearly indicated the following facts. As a result of having compared experimental results by LDV with calculated results by CFD, there is the difference about the radial component of absolute velocity, but agrees about pump performance and the tangential component comparatively well. A flow to circulate through in the impeller again is accepted by an experiment, and the sign is accepted by CFD in a specific impeller position.

Nishi, Yasuyuki; Matsuo, Nobuaki; Fukutomi, Junichiro

236

The 1st Scandinavian Conference on Viscous and T urbulent Flow in Hydraulic Machinery  

Microsoft Academic Search

Eight papers are presented which related to modeling, computation and measurement of viscous and turbulent flow with reference to fans, pumps, and hydraulic turbines. Examples of grid generation and flow analysis are given for different geometrical shapes.

Kurt Alming; J. Vassenden

1988-01-01

237

Transitions in viscous withdrawal  

NASA Astrophysics Data System (ADS)

A process analogous to flow-focusing occurs in extended and stably stratified layers of immiscible, viscous liquids. In viscous withdrawal, an axisymmetric converging flow is imposed in the upper layer. When the upper layer flow is weak, the interface forms a hump. No liquid from the lower layer is entrained. When the upper layer flow is strong, liquid from the lower layer is entrained and the interface becomes a spout. Here I summarize recent results on the fundamental mechanisms controlling these regimes. For selective withdrawal, a clear picture has emerged, with good agreement between theory, simulation and experiment. The regime ends when the viscous stress exerted by the upper layer flow overcomes surface tension, creating a saddle-node bifurcation in the hump solution. Less is understood about viscous entrainment. A long-wavelength model including only local information is degenerate, possessing many solutions for the same withdrawal condition. Including information about the global geometry removes this degeneracy but also makes the surprising prediction that global geometry can change the nature of the transition. First-order, weakly first-order or continuous transitions are all possible. How these results relate to the variety of experimental phenomena, such as stable, micron-sized spouts, intricate patterns of hysteresis and multiple stable spout states under the same condition, is at present unclear. (Includes material from joint works with Blanchette, Cohen, Kleine Berkenbusch, and Schmidt.)

Zhang, Wendy W.

2008-11-01

238

Rotating Instability of a Centrifugal Compressor with 2-Dimensional Impeller  

NASA Astrophysics Data System (ADS)

This study investigated on details of flow characteristics of a compressor with 2-dimensional impeller at various flow rates. Experiment for a low speed compressor model in a water reservoir was performed to analyze the flow field in the vaneless diffuser and volute casing, which was done by PIV measurement. It was also focused on the periodic flow patterns occurring at low flow rate near unstable operating region of the compressor. At low flow rate condition, the flow visualization clearly shows that the flow energy from impeller is highly accumulated at the compressor exit by the blockage effect of a flow damper and consequently the reverse flow occurs in the diffuser.

Kang, Kyung Jun; Shin, You Hwan; Kim, Kwang Ho

2010-06-01

239

Unsteady pressure measurements in a rotating centrifugal impeller  

NASA Astrophysics Data System (ADS)

The design of a shrouded radial test impeller which enables the application of miniature pressure transducers inside the blades is presented. An explanation of the measurement- and analysis technique is given. The results of suction side blade surface pressure measurements at several points of a performance line are presented. Two different types of diffuser rotating stall were detected. The pressure behavior at impeller stall and surge inception is demonstrated. Furthermore, the periodic engine order blade surface pressure signals at a stable operating point are shown.

Roth, G.

1992-06-01

240

Low head pumping system for fish farms  

US Patent & Trademark Office Database

An impeller pump for moving large volumes of liquid against heads of up to 1 meteris formed by a substantial circular housing having its axis substantially vertical in which an impeller is mounted for rotation on the central axis. The impeller has an maximum diameter substantially equal to the inside diameter of the housing and is formed with a hub and the plurality of blades symmetrically positioned around the hub. Each blade extends radially outward of the hub from a root to a tip and has a foil shaped cross section with a lift to drag ratio at least 75 to 1 at a Reynolds number of under 10.sup.6. Each of the blades is skewed rearward in the direction of blade rotation so that the apparent aspect ratio of blade is increased and to reduce operating noise. Each blade has an angle of attack of between 2.degree. and 6.degree. and has a rake in the direction of flow through the impeller of between 3.degree. and 7.degree.. The impeller lifts water through the housing and directs it into the fish farm.

1997-10-28

241

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

242

Development and test of a plastic deep-well pump  

NASA Astrophysics Data System (ADS)

To develop a plastic deep-well pump, three methods are proposed on structural and forming technique. First, the major hydraulic components are constructed by plastics, and the connection component is constructed by steel. Thus the pump structure is more concise and slim, greatly reducing its weight and easing its transportation, installation, and maintenance. Second, the impeller is designed by maximum diameter method. Using same pump casing, the stage head is greatly increased. Third, a sealing is formed by impeller front end face and steel end face, and two slots are designed on the impeller front end face, thus when the two end faces approach, a lubricating pair is formed, leading to an effective sealing. With above methods, the pump's axial length is greatly reduced, and its stage head is larger and more efficient. Especially, the pump's axial force is effectively balanced. To examine the above proposals, a prototype pump is constructed, and its testing results show that the pump efficiency exceeds the national standard by 6%, and the stage head is improved by 41%, meanwhile, its structure is more concise and ease of transportation. Development of this pump would provide useful experiences for further popularity of plastic deep-well pumps.

Zhang, Q. H.; Gao, X. F.; Xu, Y.; Shi, W. D.; Lu, W. G.; Liu, W.

2013-12-01

243

Transformation of vibration signals in rotary blood pumps: the diagnostic potential of pump failure.  

PubMed

Although non-destructive and continuous monitoring is indispensable for long-term circulatory support with rotary blood pumps, a practical monitoring system has not yet been developed. The objective of this study was to investigate the possibility of detecting pump failure caused by thrombus formation through the monitoring of vibration signals. The data acquisition equipment included vibration pickups, a charge amplifier, vibration analysis systems, and exclusive hardware. A pivot-bearing centrifugal pump with a mock circuit was investigated for vibration analysis. To simulate the four common areas of thrombus formation, we used a piece of silicon attached to each of the following four locations: the total area of the bottom of the impeller, an eccentric shape on the bottom of the impeller, a circular shape around the shaft top, and an eccentric shape on the top of the impeller. Vibration signals were picked up, and the power spectrum density analysis was performed at pump rotational speeds of 2100, 2400, and 3000 rpm. In this study, pump failure could be detected, and the types of imitation thrombi could be determined. We conclude that vibration detection with a computerized analysis system is a potentially valuable diagnostic tool for long-term circulatory support with rotary blood pumps. PMID:23625149

Kawahito, Koji

2013-09-01

244

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

245

Suspending Insoluble Solids Waste Tanks with Shrouded Axial Impeller Mixers  

SciTech Connect

The Savannah River Site is in the process of removing waste (sludge and salt cake) from million gallon waste tanks. The authors are conducted a test program to determine mixer requirements for suspending sludge heels using shrouded axial impeller mixers. The authors will present and discuss the data generated during the tests.

Poirier, M.R.

1998-11-09

246

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

247

Combustion of viscous hydrocarbons  

Microsoft Academic Search

A method is described for utilizing viscous hydrocarbons as combustible pre-atomized fuels, comprising: (A) forming a hydrocarbon-in-water emulsion using an effective amount of a surfactant package comprising at least one water-soluble surfactant, the hydrocarbon-in-water emulsion (1) comprising a hydrocarbon characterized by API gravity of about 20° API or less, viscosity of about 1000 centipoise or greater at 212°F., a paraffin

M. E. Hayes; K. R. Hrebenar; P. L. Murphy; L. E. Jr. Futch; J. F. Deal; P. L. Jr. Bolden

1987-01-01

248

Combustion of viscous hydrocarbons  

Microsoft Academic Search

A method is described for utilizing viscous hydrocarbons as combustible fuels comprising: (A) forming a hydrocarbosol using a surfactant package in a proportion of about 1:100 to about 1:20,000 by weight based on hydrocarbon, (1) the surfactant package comprising (a) at least one water-soluble surfactant, an effective amount of which surfactant promotes emulsification of a hydrocarbon with API gravity of

M. E. Hayes; K. R. Hrebenar; P. L. Murphy; L. E. Jr. Futch; J. F. Deal

1986-01-01

249

Low volume variable RPM submersible well pump  

SciTech Connect

This patent describes a submersible pump assembly comprising in combination: a centrifugal pump having impeller means for producing at least two flow rates for a selected head when operated at constant speed, making the pump potentially unstable, and for requiring increasing torque to produce increasing flow rates. An electric motor connects directly to the pump for driving the pump. A sensing means senses the torque output of the motor; and variable a speed drive means for varies the speed of the motor in response to the torque sensed by the sensing means to maintain a constant torque output. The constant torque applied to the pump prevents the pump from delivering more than one flow rate for a given head to stabilize the operation.

Lorett, J.A.; Vandevier, J.E.

1987-07-07

250

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

251

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

Microsoft Academic Search

An implantable, compact rotary blood pump has been newly developed using an axial flow turbo pump with hydrodynamic bearings.\\u000a The rotating impeller, which is hydrodynamically levitated with the assistance of repulsive magnetic force, has no contact\\u000a with the inner surface of the pump. To evaluate the hemodynamic performance and biocompatibility, the pump was installed into\\u000a four calves for up to

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

2011-01-01

252

Active Control of Pressure, Sound and Velocity of Centrifugal Pumps.  

National Technical Information Service (NTIS)

Measurements of velocity, pressure and sound have been obtained in a centrifugal pump with a four blade impeller rotating at speeds between 1470 rpm and 3510 rpm to improve understanding of noise generation and to investigate the feasibility of reducing f...

D. G. Tse H. McDonald J. H. Whitelaw J. S. Sabnis

1992-01-01

253

Probabilistic Reliability Validation of an Impeller Using DARWIN(tm)  

NASA Astrophysics Data System (ADS)

DARWIN (Design Assessment of Reliability With INspection) is a computer program for the prediction of the probability of fracture in aircraft engine rotor disks. Its risk prediction process includes finite element analysis based stress distribution, fracture mechanics based crack growth calculations, material defect distributions and nondestructive inspection simulation. Southwest Research Institute is developing this program as part of the Turbine Rotor Material Design (TRMD) contract under FAA (Federal Aviation Administration) sponsorship. As part of the TRMD program, Honeywell is conducting failure risk prediction validation of DARWIN for hard alpha analysis using actual component experience. Specifically, the case considered herein involves a fielded impeller that has accumulated significant service cycles but has not experienced any hard alpha issues in the field. However, during routine production overspeed an impeller of this type did experience a spin-pit event due to a hard alpha inclusion. This case challenges the two extremes of risk prediction process. First, the overspeed spin-pit case will be analyzed for DARWIN validation from the standpoint of high failures per cycle (single cycle failure). Second, the same impeller will be analyzed using field conditions for DARWIN validation from the "null hypothesis" (extremely low failures per cycle) probability standpoint. Figure 1 shows the stress results for the spin-pit overspeed condition. This work presents the results of the DARWIN predicted failure risk probability and shows calibration results with both field and spin-pit experience.

Muju, Sandeep; Nelson, Rick; Lentz, Jeff

2002-10-01

254

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

255

Response History Made…International Participants Join in United Effort to Improve Heavy Viscous Oil Marine Response Technology  

Microsoft Academic Search

The Joint Viscous Oil Pumping System (JVOPS) Workshop was conducted in Houma, LA, USA from 01 - 15 December 2003. The Workshop was planned and executed by the JVOPS Workgroup, a multi-national group of engineers, scientists, pollution response equipment manufacturers and first responders dedicated to improving heavy viscous oil response worldwide. The purpose of the Workshop was to improve the

Commander Michael Drieu; Lieutenant Commander; Peter C. Nourse; Craig O. Moffat

256

Hydrodynamics in a vessel stirred by simple and double helical ribbon impellers  

NASA Astrophysics Data System (ADS)

The present paper treats the agitation of shear thinning fluids in a cylindrical unbaffled vessel with a flat-bottom. Two kinds of impellers have been used: simple and double helical ribbons. This work is achieved with the help of CFD package (CFX-12.0), which is based on the finite volume method to solve the continuity and momentum equations. The effect of impeller rotational speed, fluid rheology, impeller size, impeller clearance from the tank bottom on the flow fields and power consumption have been investigated. Finally, a comparison between the two impellers is made. It was found that the best performance is obtained with double helical ribbon impeller placed at the middle of the tank, with moderate blade size and operating at Re g > 20. Our results have been compared with those of other literatures and a satisfactory agreement is observed.

Ameur, Houari; Bouzit, Mohamed; Ghenaim, Abdellah

2013-03-01

257

Bulk viscous cosmology  

SciTech Connect

We propose a scenario in which the dark components of the Universe are manifestations of a single bulk viscous fluid. Using dynamical system methods, a qualitative study of the homogeneous, isotropic background scenario is performed in order to determine the phase space of all possible solutions. The specific model which we investigate shares similarities with a generalized Chaplygin gas in the background but is characterized by nonadiabatic pressure perturbations. This model is tested against supernova type Ia and matter power spectrum data. Different from other unified descriptions of dark matter and dark energy, the matter power spectrum is well behaved, i.e., there are no instabilities or oscillations on small perturbation scales. The model is competitive in comparison with the currently most popular proposals for the description of the cosmological dark sector.

Colistete, R. Jr.; Fabris, J. C.; Zimdahl, W. [Universidade Federal do Espirito Santo, Departamento de Fisica, Av. Fernando Ferrari, 514, Campus de Goiabeiras, CEP 29075-910, Vitoria, Espirito Santo (Brazil); Tossa, J. [Institut de Mathematiques et de Sciences Physiques-IMSP, Universite d'Abomey-Calavi, BP613, Porto Novo (Benin)

2007-11-15

258

Combustion of viscous hydrocarbons  

SciTech Connect

A method is described for utilizing viscous hydrocarbons as combustible pre-atomized fuels, comprising: (A) forming a hydrocarbon-in-water emulsion using an effective amount of a surfactant package comprising at least one water-soluble surfactant, the hydrocarbon-in-water emulsion (1) comprising a hydrocarbon characterized by API gravity of about 20/sup 0/ API or less, viscosity of about 1000 centipoise or greater at 212/sup 0/F., a paraffin content of about 50% by weight or less and, an aromatic content of about 15% by weight or greater, and (2) having a hydrocarbon water ratio from about 60:40 to about 90:10 by volume; and (B) burning the resultant hydrocarbon-in-water emulsion.

Hayes, M.E.; Hrebenar, K.R.; Murphy, P.L.; Futch, L.E. Jr.; Deal, J.F. III; Bolden, P.L. Jr.

1987-08-04

259

Combustion of viscous hydrocarbons  

SciTech Connect

A method is described for utilizing viscous hydrocarbons as combustible fuels comprising: (A) forming a hydrocarbosol using a surfactant package in a proportion of about 1:100 to about 1:20,000 by weight based on hydrocarbon, (1) the surfactant package comprising (a) at least one water-soluble surfactant, an effective amount of which surfactant promotes emulsification of a hydrocarbon with API gravity of about 20/sup 0//sup o/ API or less; and (b) at least one water-soluble bioemulsifier, being a microboally-derived substance which predominantly resides at hydrocarbon/water interfaces to substantially surround hydrocarbon droplets in hydrocarbon-in-water emulsions; (2) the hydrocarbosol (a) comprising a hydrocarbon characterized by an API gravity of about 20/sup 0//sup o/ API or less; (b) having a hydrocarbon:water ratio of about 70:30 by volume; and (B) burning the resultant hydrocarbosol.

Hayes, M.E.; Hrebenar, K.R.; Murphy, P.L.; Futch, L.E. Jr.; Deal, J.F. III

1986-10-21

260

Viscous grounding lines  

NASA Astrophysics Data System (ADS)

We have used simple laboratory experiments with viscous fluids to explore the dynamics of grounding lines between Antarctic marine ice sheets and the freely floating ice shelves into which they develop. Ice sheets are shear-dominated gravity currents, while ice shelves are extensional gravity currents with zero shear to leading order. Though ice sheets have non-Newtonian rheology, fundamental aspects of their flow can be explored using Newtonian fluid mechanics. We have derived a mathematical model of this flow that incorporates a new dynamic boundary condition for the position of the grounding line, where the gravity current loses contact with the solid base. Good agreement between our theoretical predictions and our experimental measurements, made using gravity currents of syrup flowing down a rigid slope into a deep, dense salt solution, gives confidence in the fundamental assumptions of our model, which can be incorporated into shallow-ice models to make important predictions regarding the dynamical stability of marine ice sheets.

Worster, Grae; Huppert, Herbert; Robison, Rosalyn; Nandkishore, Rahul; Rajah, Luke

2008-11-01

261

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

262

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

263

An experimental study of a small high speed LH2 rocket pump: Fundamental mechanical design  

NASA Astrophysics Data System (ADS)

A small high speed Liquid Hydrogen (LH2) pump was designed, fabricated, and tested in order to obtain technical data necessary for the development of upper stage rocket engines, e.g., the LE-5 and Orbiter Transfer Vehicle (OTV) engines. The pump's basic mechanical design is described, as well as its mechanical performance during tests using LH2 (both at nominal operating and rapid start and stop conditions). It was confirmed that the same materials employed for liquid oxygen pump components can be used, except for the impeller. An impeller made of titanium alloy (Ti-5Al-2.5Sn) was machined and then diffusion bonded, and subsequently withstood a high speed operating condition (50,000 rpm) for 350 sec. A balance piston configuration was selected for axial thrust control, where the impeller acts as a balance disk. The piston's performance was satisfactory, although the impeller's balance position during the tests was different from design calculations. Post-test examinations revealed light rubbing traces on the impeller and casing at the balance piston orifice. This positional discrepancy was caused by an inaccurate estimate of the orifice flow coefficients and leakage flow rate. Stress analysis on other components and machine specifications for critical mating parts were also verified as satisfactory. Self lubricated ball bearings and rotating shaft seals showed adequate performance. Results indicate that smooth operation was achieved, thus confirming the soundness of the pump's mechanical design.

Kikuchi, Masataka; Suzuki, Mineo; Shimura, Takashi; Watanabe, Mitsuo; Kamijo, Kenjiro; Nosaka, Masataka; Warashina, Shougo

1991-09-01

264

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

NASA Astrophysics Data System (ADS)

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

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

265

Numerical simulations of solid-liquid stirred tank with an improved Intermig impeller  

NASA Astrophysics Data System (ADS)

Numerical simulations of solid-liquid mixing in a stirred tank with an improved Intermig impeller were performed by adopting standard ?-? turbulence model coupled with Eulerian granular multiphase model. An unsteady sliding mesh approach was used to simulate the impeller rotation. The flow field, solids hold-up and power consumptions were investigated in the solid-liquid mixing system. Compared to the standard Intermig impeller, the improved Intermig impeller coupled with the special sloped baffle could promote the fluid circulation, creating better solid suspension and consuming lesser power.

Zhao, Hongliang; Zhang, Ting'an; Liu, Yan; Zhang, Zimu; Zhang, Chao

2013-06-01

266

Optimal Navier-Stokes Design of Compressor Impellers Using Evolutionary Computation  

NASA Astrophysics Data System (ADS)

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

Benini, Ernesto

2003-09-01

267

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

268

Constraining relativistic viscous hydrodynamical evolution  

SciTech Connect

We show that by requiring positivity of the longitudinal pressure it is possible to constrain the initial conditions one can use in second-order viscous hydrodynamical simulations of ultrarelativistic heavy-ion collisions. We demonstrate this explicitly for (0+1)-dimensional viscous hydrodynamics and discuss how the constraint extends to higher dimensions. Additionally, we present an analytic approximation to the solution of (0+1)-dimensional second-order viscous hydrodynamical evolution equations appropriate to describe the evolution of matter in an ultrarelativistic heavy-ion collision.

Martinez, Mauricio [Helmholtz Research School and Otto Stern School, Goethe-Universitaet Frankfurt am Main Ruth-Moufang-Strasse 1, D-60438 Frankfurt am Main (Germany); Strickland, Michael [Physics Department, Gettysburg College Gettysburg, Pennsylvania 17325 (United States)

2009-04-15

269

Split driveshaft pump for hazardous fluids  

DOEpatents

A pump having a split driveshaft for use in pumping hazardous fluids wherein only one driveshaft becomes contaminated by the fluid while the second remains isolated from the fluid. The pump has a first portion and a second portion. The first portion contains a pump motor, the first driveshaft, a support pedestal, and vapor barriers and seals. The second portion contains a second, self-lubricating driveshaft and an impeller. The first and second driveshafts are connected together by a releasable coupling. A shield and a slinger deployed below the coupling prevent fluid from the second portion from reaching the first portion. In operation, only the second assembly comes into contact with the fluid being pumped, so the risk of contamination of the first portion by the hazardous fluid is reduced. The first assembly can be removed for repairs or routine maintenance by decoupling the first and second driveshafts and disconnecting the motor from the casing.

Evans, II, Thomas P. (Aiken, SC); Purohit, Jwalit J. (Evans, GA); Fazio, John M. (Orchard Park, NY)

1995-01-01

270

Split driveshaft pump for hazardous fluids  

SciTech Connect

A pump is described having a split driveshaft for use in pumping hazardous fluids wherein only one driveshaft becomes contaminated by the fluid while the second remains isolated from the fluid. The pump has a first portion and a second portion. The first portion contains a pump motor, the first driveshaft, a support pedestal, and vapor barriers and seals. The second portion contains a second, self-lubricating driveshaft and an impeller. The first and second driveshafts are connected together by a releasable coupling. A shield and a slinger deployed below the coupling prevent fluid from the second portion from reaching the first portion. In operation, only the second assembly comes into contact with the fluid being pumped, so the risk of contamination of the first portion by the hazardous fluid is reduced. The first assembly can be removed for repairs or routine maintenance by decoupling the first and second driveshafts and disconnecting the motor from the casing. 1 figure.

Evans, T.P. II; Purohit, J.J.; Fazio, J.M.

1995-01-10

271

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

272

Computational Flow Study of the Continuous Flow Ventricular Assist Device, Prototype Number 3 Blood Pump  

Microsoft Academic Search

Abstract: A computational,fluid dynamics,study of blood flow in the continuous flow ventricular assist device, Pro- totype No. 3 (CFVAD3), which consists of a 4 blade shrouded impeller fully supported in magnetic bearings, was,performed.,This study focused,on the regions within the pump where return flow occurs to the pump inlet, and where,potentially damaging,shear stresses and,flow stag- nation,might,occur: the impeller,blade passages,and,the narrow,gap clearance,regions

Jay B. Anderson; Houston G. Wood; Paul E. Allaire; G. Bearnson; P. Khanwilkar

2000-01-01

273

Interacting viscous dark fluids  

NASA Astrophysics Data System (ADS)

We revise the conditions for the physical viability of a cosmological model in which dark matter has bulk viscosity and also interacts with dark energy. We have also included radiation and baryonic matter components; all matter components are represented by perfect fluids, except for the dark matter one that is modeled as an imperfect fluid. We impose upon the model the condition of a complete cosmological dynamics that results in an either null or negative bulk viscosity, but the latter also disagrees with the local second law of thermodynamics (LSLT). The model is also compared with cosmological observations at different redshifts: type Ia supernova, the acoustic peak of baryon acoustic oscillation, the Hubble parameter H(z), and the angular scale of the cosmic microwave background encoded in the first peak. Taken together, observations consistently point to a negative value of the bulk viscous coefficient, that is in disagreement with the LSLT. From the different cases that we study, the best model that we find corresponds to the case of a dark matter with a null viscosity, interacting with a phantom dark energy. Also, overall the fitting procedure shows no preference for the model over the standard ?CDM model.

Avelino, Arturo; Leyva, Yoelsy; Ureña-López, L. Arturo

2013-12-01

274

Sliding friction in viscous hydrodynamics  

SciTech Connect

Basset's collective friction coefficient for a viscous fluid flowing past a rough solid surface is obtained - analytically - as an intrinsic consequence of the Navier-Stokes equations by treating the surface as a source of vorticity.

Dekker, H.

1989-04-10

275

A multiple disk centrifugal pump as a blood flow device  

Microsoft Academic Search

A study of a multiple-disk, shear force, valveless centrifugal pump to determine its suitability as a blood flow device is discussed. A pulsatile version of the Tesla viscous flow turbine was designed by modifying the original steady flow pump concept to produce physiological pressures and flows with the aid of controlling circuitry. Pressures and flows from this pump were compared

GERALD E. MILLER; BRADLEY D. ETTER; JEAN M. DORSI

1990-01-01

276

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

NASA Technical Reports Server (NTRS)

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

1991-01-01

277

A magnetically levitated centrifugal blood pump with a simple-structured disposable pump head.  

PubMed

A magnetically levitated centrifugal blood pump (MedTech Dispo) has been developed for use in a disposable extracorporeal system. The design of the pump is intended to eliminate mechanical contact with the impeller, to facilitate a simple disposable mechanism, and to reduce the blood-heating effects that are caused by motors and magnetic bearings. The bearing rotor attached to the impeller is suspended by a two degrees-of-freedom controlled radial magnetic bearing stator, which is situated outside the rotor. In the space inside the ringlike rotor, a magnetic coupling disk is placed to rotate the rotor and to ensure that the pump head is thermally isolated from the motor. In this system, the rotor can exhibit high passive stiffness due to the novel design of the closed magnetic circuits. The disposable pump head, which has a priming volume of 23 mL, consists of top and bottom housings, an impeller, and a rotor with a diameter of 50 mm. The pump can provide a head pressure of more than 300 mm Hg against a flow of 5 L/min. The normalized index of hemolysis of the MedTech Dispo is 0.0025 +/- 0.0005 g/100 L at 5 L/min against 250 mm Hg. This is one-seventh of the equivalent figure for a Bio Pump BPX-80 (Medtronic, Inc., Minneapolis, MN, USA), which has a value of 0.0170 +/- 0.0096 g/100 L. These results show that the MedTech Dispo offers high pumping performance and low blood trauma. PMID:18638307

Hijikata, Wataru; Shinshi, Tadahiko; Asama, Junichi; Li, Lichuan; Hoshi, Hideo; Takatani, Setsuo; Shimokohbe, Akira

2008-07-01

278

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

279

Theoretical Study of Fluid Forces on a Centrifugal Impeller Rotating and Whirling in a Vaned Diffuser.  

National Technical Information Service (NTIS)

The fluid forces on a centrifugal impeller rotating and whirling in a vaned diffuser are analyzed on the assumption that the number of impeller and diffuser vanes is so large that the flows are perfectly guided by the vanes. The flow is taken to be two di...

Y. Tsujimoto A. J. Acosta Y. Yoshida

1989-01-01

280

Aerodynamic Tests on a Centrifugal Fan Impeller Model with Swept-Back Blades.  

National Technical Information Service (NTIS)

Experiments were carried out on the NRC Low Speed Centrifugal Compressor Rig on a 4-foot - 101/2-inch diameter model of a fan impeller with highly swept-back vanes. The impeller was run over a range of speeds and throttle settings to explore the whole ope...

H. S. Fowler

1971-01-01

281

The experimental study of matching between centrifugal compressor impeller and diffuser  

Microsoft Academic Search

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

H. Tamaki; H. Nakao; M. Saito

1999-01-01

282

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

283

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

284

Effect of Area Ratio on the Performance of a 5.5:1 Pressure Ratio Centrifugal Impeller.  

National Technical Information Service (NTIS)

A centrifugal impeller which was initially designed for a pressure ratio of approximately 5.5 and a mass flow rate of 0.959 kg/sec was tested with a vaneless diffuser for a range of design point impeller area ratios from 2.322 to 2.945. The impeller area ...

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

1986-01-01

285

Effect of Area Ratio on the Performance of a 5.5:1 Pressure Ratio Centrifugal Impeller.  

National Technical Information Service (NTIS)

A centrifugal impeller which was initially designed for a pressure ratio of approximately 5.5 and a mass flow rate of 0.959 kg/sec was tested with a vaneless for a range of design point impeller area ratios from 2.322 to 2.945. The impeller area ratio was...

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

1985-01-01

286

Computer-aided measurement plan for an impeller on a coordinate measurement machine with a rotating and tilting probe  

Microsoft Academic Search

This paper presents a computer-aided measurement plan (CAMP) for an impeller on a coordinate measurement machine (CMM) with a rotating\\/tilting probe. The blade surfaces of a machined impeller were measured exactly to secure the machining tolerance and surface finish of the impeller. CMM with a rotating and tilting probe is commonly used for this measurement. However, it is not easy

Eun-Young Heo; Dong-Won Kim; Jong-Yeong Lee; Kyoung-Yun Kim

2008-01-01

287

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

288

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

289

A straight path centrifugal blood pump concept in the Capiox centrifugal pump.  

PubMed

This article describes comparative studies of a newly developed "straight path" centrifugal pump (Capiox centrifugal pump) targeted for open-heart surgery and circulatory support. A unique straight path design of the rotor was very effective in reducing the pump's rotational speed and prime volume. This pump was evaluated for hydraulics, hemolysis, depriming characteristics, cavitation, and heat generation. Two commercially available centrifugal pumps, the Biomedicus cone-type pump and the Sarns 3M impeller-type pump, were used as controls. The new pump required the lowest pump speed to produce the same flow rates under the same pressure loads and demonstrated the lowest hemolysis and the lowest temperature rise with the outlet clamped. The air volume required to deprime the new pump was one-third to one-half that for the other pumps, and no sign of cavitation was observed even if a small amount of air was introduced to the pump inlet under a negative pressure of 200 mm Hg. PMID:8338432

Kijima, T; Oshiyama, H; Horiuchi, K; Nogawa, A; Hamasaki, H; Amano, N; Nojiri, C; Fukasawa, H; Akutsu, T

1993-07-01

290

Activities of the NASA/Marshall Space Flight Center pump stage technology team  

NASA Technical Reports Server (NTRS)

In order to advance rocket propulsion technology, the Consortium for Computational Fluid Dynamics (CFD) Application in Propulsion Technology has been formed at Marshall Space Flight Center (MSFC). The Consortium consists of three Teams: the turbine stage team, the pump stage team (PST), and the combustion devices team. The PST has formulated and is implementing a plan for pump technology development whose end product will be validated CFD codes suitable for application to pump components, test data suitable for validating CFD codes, and advanced pump components optimized using CFD codes. The PST's work during the fall of 1991 and the winter and spring of 1992 is discussed in this paper. This work is highlighted by CFD analyses of an advanced impeller design and collection of laser two-focus velocimeter data for the Space Shuttle Main Engine High Pressure Fuel Pump impeller.

Garcia, R.; Mcconnaughey, P.; Eastland, A.

1992-01-01

291

Cavitation performance evaluation for a condensate pump  

NASA Astrophysics Data System (ADS)

Cavitation in a condensate pump with specific speed of 95 m·m3s-1·min-1 was treated in this study. Cavitation performance for the pump was tested experimentally, and the steady state cavitating flows in the pump impeller were simulated by RANS method as well as a homogeneous cavitation model. It is noted that cavitating flow simulation reasonably depicted cavitation development in the pump. Compared to the tested results, the numerical simulation basically predicted later performance drops due to cavitation. Unfortunately, the cavitation simulation at the operation condition of 50% best efficiency point could not predict the head drop up to 3%. By applying the concept of relative cavity length cavitation performance evaluation is achieved. For better application, future study is necessary to establish the relation between relative cavity length and performance drop.

Yu, A.; Yu, W. P.; Pan, Z. B.; Luo, X. W.; Ji, B.; Y Xu, H.

2013-12-01

292

Investigations on viscous dissipation effect of liquid flow in microtubes  

NASA Astrophysics Data System (ADS)

The experimental and numerical investigations are carried out to explore the viscous dissipation effect during de-ionized ultra pure water flowing through smooth quartz glass microtubes with inner diameters of 25 and 50 m, and the Reynolds number varies in the range from 0 to 680. The viscous dissipation characteristic in microtubes is numerically calculated by a 2-D model and the Electrical Double Layer (EDL) effect on the flow is considered. A new criterion V c demonstrating the law of the viscous dissipation effect in microtubes is summed up with the numerical simulation results. By applying the micro-area thermal-imaging technology and a series of correction tests, the viscous heating temperature increment in the microtube can be exactly measured by an IR camera with a special magnifying lens. Furthermore, the temperature increment of the working fluid due to the heat generated by the pump is also considered in the experimental investigation. The comparisons among the experimental results, the numerical predictions and the new theoretical correlations are made in the present research, which indicates the experimental data are in rough accordance with the numerical and the theoretical results.

Guan, Ning; Liu, Zhi-Gang; Takie, Masahiro; Zhang, Cheng-Wu

2011-06-01

293

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

294

Performance analysis of mini centrifugal pump with splitter blades  

NASA Astrophysics Data System (ADS)

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

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

2013-12-01

295

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

NASA Astrophysics Data System (ADS)

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

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

2013-03-01

296

Space Shuttle Main Engine Structural Analysis and Data Reduction/Evaluation. Volume 2: High Pressure Oxidizer Turbo-Pump Turbine End Bearing Analysis.  

National Technical Information Service (NTIS)

The high-pressure oxidizer turbopump (HPOTP) consists of two centrifugal pumps, on a common shaft, that are directly driven by a hot-gas turbine. Pump shaft axial thrust is balanced in that the double-entry main inducer/impeller is inherently balanced and...

G. A. Sisk

1989-01-01

297

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

298

Counter-rotating type pump-turbine unit cooperating with wind power unit  

NASA Astrophysics Data System (ADS)

This serial research proposes the hybrid power system combined the wind power unit with the counter-rotating type pump-turbine unit, to provide the constant output for the grid system, even at the suddenly fluctuating/turbulent wind. In this paper, the tandem impellers of the counter-rotating type pumping unit was operated at the turbine mode, and the performances and the flow conditions were investigated numerically and experimentally. The 3-D turbulent flows in the runners were simulated at the steady state condition by using the commercial CFD code of ANSYS-CFX ver.12 with the SST turbulence model. While providing the pump unit for the turbine mode, the maximum hydraulic efficiency is close to one of the counter-rotating type hydroelectric unit designed exclusively for the turbine mode. Besides, the runner/impeller of the unit works evidently so as to coincide the angular momentum change through the front runners/impellers with that through the rear runners/impellers, namely to take the axial flow at not only the inlet but also the outlet without the guide vanes. These results show that this type of unit is effective to work at not only the pumping but also the turbine modes.

Murakami, Tengen; Kanemoto, Toshiaki

2013-02-01

299

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

Microsoft Academic Search

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

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

2008-01-01

300

Aspects of causal viscous hydrodynamics  

SciTech Connect

We investigate the phenomenology of freely expanding fluids, with different material properties, evolving through the Israel-Stewart (IS) causal viscous hydrodynamics, and compare our results with those obtained in the relativistic Eckart-Landau-Navier-Stokes (ELNS) acausal viscous hydrodynamics. Through the analysis of scaling invariants we give a definition of thermalization time that can be self-consistently determined in viscous hydrodynamics. Next we construct the solutions for one-dimensional boost-invariant flows. Expansion of viscous fluids is slower than that of one-dimensional ideal fluids, resulting in entropy production. At late times, these flows are reasonably well approximated by solutions obtained in ELNS hydrodynamics. Estimates of initial energy densities from observed final values are strongly dependent on the dynamics one chooses. For the same material, and the same final state, IS hydrodynamics gives the smallest initial energy density. We also study fluctuations about these one-dimensional boost-invariant backgrounds; they are damped in ELNS hydrodynamics but can become sound waves in IS hydrodynamics. The difference is obvious in power spectra due to clear signals of wave-interference in IS hydrodynamics, which is completely absent in ELNS dynamics.

Bhalerao, R. S.; Gupta, Sourendu [Department of Theoretical Physics, Tata Institute of Fundamental Research, Homi Bhabha Road, Mumbai 400005 (India)

2008-01-15

301

No drive line, no seal, no bearing and no wear: magnetics for impeller suspension and flow assessment in a new VAD.  

PubMed

The new magnetically suspended axial pump is free of seals, bearings, mechanical friction and wear. In the absence of a drive shaft or flow meter, pump flow assessment is made with an algorithm based on currents required for impeller rotation and stabilization. The aim of this study is to validate pump performance, algorithm-based flow and effective flow. A series of bovine experiments was realized after equipment with pressure transducers, continuous-cardiac-output-catheter, intracardiac ultrasound (AcuNav) over 6 h. Pump implantation was through a median sternotomy (LV-->VAD-->calibrated transonic-flow-probe-->aorta). A transonic-HT311-flow-probe was fixed onto the outflow cannula for flow comparison. Animals were electively sacrificed and at necropsy systematic pump inspection and renal embolus score was realized. Observation period was 340+/-62.4 min. The axial pump generated a mean arterial pressure of 58.8+/-14.3 mmHg (max 117 mmHg) running at a speed of 6591.3+/-1395.4 rev./min (min 5000/max 8500 rev./min) and generating 2.5+/-1.0 l/min (min 1.4/max 6.0 l/min) of flow. Correlation between the results of the pump flow algorithm and measured pump flow was linear (y=1.0339x, R2=0.9357). VAD explants were free of macroscopic thrombi. Renal embolus score was 0+/-0. The magnetically suspended axial flow pump provides excellent left ventricular support. The pump flow algorithm used is accurate and reliable. Therefore, there is no need for direct flow measurement. PMID:17670254

Huber, Christoph H; Tozzi, Piergiorgio; Hurni, Michel; von Segesser, Ludwig K

2004-06-01

302

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 100µm can be attained at a design bearing gap of 150 µm and at a groove depth of 100µm. PMID:24110291

Yamane, T; Kitamura, K

2013-01-01

303

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

304

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

305

Three-Dimensional Flow Analysis Inside Consortium Impeller at Design and Off-Design Conditions  

NASA Technical Reports Server (NTRS)

Three-dimensional flow fields inside the Consortium impeller were analyzed with a Navier-Stokes code. The numerical results at the design and off-design conditions are compared with the experimental data.

Hah, C.; Loellbach, J.; Tsung, F.-L.; Greenwald, D. A.; Garcia, Roberto

1993-01-01

306

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

National Technical Information Service (NTIS)

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. Li...

J. Gayda T. P. Gabb

2006-01-01

307

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

NASA Astrophysics Data System (ADS)

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

1992-07-01

308

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

309

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

NASA Astrophysics Data System (ADS)

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

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

2013-12-01

310

An improved large eddy simulation of two-phase flows in a pump impeller  

Microsoft Academic Search

An improved large eddy simulation using a dynamic second-order sub-grid-scale (SGS) stress model has been developed to model\\u000a the governing equations of dense turbulent particle-liquid two-phase flows in a rotating coordinate system, and continuity\\u000a is conserved by a mass-weighted method to solve the filtered governing equations. In the current second-order SGS model, the\\u000a SGS stress is a function of both

Xuelin Tang; Fujun Wang; Yulin Wu

2007-01-01

311

Structural optimization of a centrifugal impeller using differential evolution in CATIA™ environment  

Microsoft Academic Search

A Differential Evolution (DE) algorithm is used to optimize the backface geometry of a centrifugal impeller, with respect\\u000a to the calculated maximum stress, in order to extend its overspeed limits. A detailed fully parametric 3D model of the impeller\\u000a was initially constructed using CATIA V5; the backface geometry is defined using a Bezier curve with its parameters used as\\u000a design

I. M. Valakos; M. S. Ntipteni; I. K. Nikolos

2007-01-01

312

Weldability of 17-4 PH stainless steel in centrifugal compressor impeller applications  

Microsoft Academic Search

Weldability of 17-4 PH stainless steel for centrifugal compressor impeller was considered. Welding tests were carried out on the precipitation-hardened steel of the 17-4 PH type. Possibilities of joining centrifugal compressor impeller parts as important elements of turbo machines were considered. Two means of welding (111) and (114), as well as following heat treatment have been considered. The best results:

J. Nowacki

2004-01-01

313

Effects of rotating impeller degassing on microstructure and mechanical properties of the A356 scraps  

Microsoft Academic Search

The rotating impeller degassing technique was used for degassing of A356 scrap melt which had been protected and purified with an RE-containing JDN-I flux. Results indicated that the modification of eutectic silicon was faded and the mechanical properties of the alloy became worse after rotating impeller degassing and that the tensile strength and elongation of the scrap A356 alloy which

Hongjun Ni; Baode Sun; Haiyan Jiang; Wenjiang Ding

2003-01-01

314

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

315

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

Microsoft Academic Search

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

K. Bammert; M. Rautenberg; P. Knapp

1980-01-01

316

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

317

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

318

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

Microsoft Academic Search

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

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

2010-01-01

319

Miscible viscous fingering in microgravity  

NASA Astrophysics Data System (ADS)

To address the issue of miscible viscous fingering instability in buoyancy free conditions, experiments have been performed under microgravity conditions in parabolic flights. A Hele-Shaw cell, two parallel plates separated by a small gap, has been used with two miscible fluids of viscosity ratio 100 (the injected fluid is the less viscous). The influence of the initial thickness of the pseudointerface between the two fluids has been studied, using flow rates large enough to prevent further mixing during displacement. The selected wavelength, measured on the observed fingering pattern, does not depend on the initial front thickness: It is around three times the gap of the cell, i.e., significantly lower than the value of five, observed on earth. However, the initial thickness does control the displacement length required for the instability to occur. Our results are in reasonable agreement with existing and new numerical simulations.

Aubertin, A.; Gauthier, G.; Martin, J.; Salin, D.; Talon, L.

2009-05-01

320

The Hydrodynamics of Roller Pumps and Their Implication to Hemolysis.  

National Technical Information Service (NTIS)

The peristaltic flow inside the tube of a roller pump is investigated with the assumptions that the fluid is Newtonian and that viscous forces dominate inertia. The output of the pump and the pressure and shear stress distributions are given in closed for...

M. Y. Jaffrin J. R. Meginniss

1971-01-01

321

Flow Analysis of the Cleveland Clinic Centrifugal Pump  

NASA Technical Reports Server (NTRS)

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

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

1997-01-01

322

Self-priming centrifugal pumps are efficient, easy to service  

SciTech Connect

A series of self-priming centrifugal pumps was awarded Top Honors in the process pump category of the 1982 Chemical Processing Vaaler competition because the judges were favorably impressed by the high operating efficiency over a wide range of flow conditions, and the easy-to-service design that reduces overall operating costs. The self-priming pumps also offer certain advantages over conventional vertical or submerged pumps in wet pit service. Features for up to 75% operating efficiency include a unique hydraulic design to eliminate the need for close tolerances, a smooth-walled volute casing to minimize friction loss and drag, and a multi-vane open impeller that will handle solids up to 1 1/4'' in diameter. The pump can handle varying loads with very little loss of efficiency.

Not Available

1982-11-01

323

A Practical Method for Patterning Lumens through ECM Hydrogels via Viscous Finger Patterning  

PubMed Central

Extracellular matrix (ECM) hydrogels with patterned lumens have been used as a framework to generate more physiologically relevant models of tissues, such as vessels and mammary ducts, for biological investigations. However, these models have not found widespread use in research labs or in high-throughput screening applications in large part because the basic methods for generating the lumen structures are generally cumbersome and slow. Here we present viscous finger patterning, a technique to generate lumens through ECM hydrogels in microchannels that can be accomplished using manual or automated pipetting. Passive pumping is used to flow culture media through an unpolymerized hydrogel, creating a lumen through the hydrogel that is subsequently polymerized. Viscous finger patterning takes advantage of viscous fingering, the fluid dynamics phenomenon where a less viscous fluid will flow through and displace a more viscous fluid. We have characterized the technique and used it to create a variety of channel geometries and ECM hydrogel compositions, as well as for the generation of lumens surrounded by multiple hydrogel layers. Because viscous finger patterning can be performed with automated liquid handling systems, high-throughput generation of ECM hydrogels with patterned lumen is enabled. The ability to rapidly and cost-effectively create large numbers of lumens in natural polymers overcomes a critical barrier to the use of more physiologically relevant tissue models in a variety of biological studies and drug screening applications.

Bischel, Lauren L.; Lee, Sang-Hoon; Beebe, David J.

2012-01-01

324

Development of Terumo implantable left ventricular assist system (T-ILVAS) with a magnetically suspended centrifugal pump  

Microsoft Academic Search

The research group of Terumo, NTN, and the Setsunan University have been developing an implantable left ventricular assist system (T-ILVAS) featuring a centrifugal blood pump with a magnetically suspended impeller (MSCP). The present study describes recent progress in the development of the T-ILVAS, focusing on ex vivo and in vivo evaluations of the prototype MSCP. The MSCP is composed of

Chisato Nojiri; Toshihiko Kijima; Jun Maekawa; Kunio Horiuchi; Takayuki Kido; Tomoko Sugiyama; Takehisa Mori; Naoya Sugiura; Takehiko Asada; Takayoshi Ozaki; Minoru Suzuki; Teruaki Akamatsu; Tetsuzo Akutsu

1999-01-01

325

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

326

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

PubMed

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

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

1989-11-01

327

The experimental study of matching between centrifugal compressor impeller and diffuser  

SciTech Connect

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

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

1999-01-01

328

Computation of viscous incompressible flows  

NASA Technical Reports Server (NTRS)

Incompressible Navier-Stokes solution methods and their applications to three-dimensional flows are discussed. A brief review of existing methods is given followed by a detailed description of recent progress on development of three-dimensional generalized flow solvers. Emphasis is placed on primitive variable formulations which are most promising and flexible for general three-dimensional computations of viscous incompressible flows. Both steady- and unsteady-solution algorithms and their salient features are discussed. Finally, examples of real world applications of these flow solvers are given.

Kwak, Dochan

1989-01-01

329

Inducer analysis/pump model development  

NASA Technical Reports Server (NTRS)

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

Cheng, Gary C.

1994-01-01

330

Viscous fluid interpretation of some exact solutions  

SciTech Connect

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

Carot, J.; Ibanez, J.

1985-09-01

331

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

332

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

NASA Astrophysics Data System (ADS)

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

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

2010-08-01

333

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

NASA Astrophysics Data System (ADS)

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

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

2012-11-01

334

Current status of the gyro centrifugal blood pump--development of the permanently implantable centrifugal blood pump as a biventricular assist device (NEDO project).  

PubMed

The New Energy and Industrial Technology Development Organization (NEDO) project was started in 1995. The goal is the development of a multipurpose, totally implantable biventricular assist device (BVAD) that can be used for any patient who suffers from severe heart failure. Our C1E3 (two-week pump) centrifugal pump, called the Gyro pump, has three design characteristics: a magnetic coupling and double pivot bearing system, an eccentric inlet port, and secondary vanes on the bottom of the impeller. The pump was miniaturized. The C1E3 evolved into the NEDO PI-601, a totally implantable centrifugal pump for BVAD. The current NEDO PI-710 pump (five-year pump) system includes a centrifugal pump with pivot bearings, a hydraulically-levitated impeller, an rpm-controlled miniaturized actuator (all-in-one actuator plus controller), an emergency clamp on the left outflow, and a Frank-Starling-type flow control. The final mass production model is now finalized, and the final animal study and two-year endurance studies are ongoing. PMID:15385004

Nosé, Yukihiko; Furukawa, Kojiro

2004-10-01

335

Fluid Mixing from Viscous Fingering  

NASA Astrophysics Data System (ADS)

Fluid mixing is an important and complex phenomenon. It plays a fundamental role in natural processes, including groundwater flows in heterogeneous media, reactive flows, mantle convection, debris gravity currents, and bacterial locomotion. Mixing at low Reynolds numbers is a notoriously difficult problem because it cannot rely on turbulence. Mixing efficiency at low Reynolds numbers can be enhanced by exploiting hydrodynamic instabilities that induce heterogeneity and disorder in the flow. The unstable displacement of fluids with different viscosities, or viscous fingering, provides a powerful mechanism to increase fluid-fluid interfacial area and enhance mixing. Here we describe the dissipative structure of miscible viscous fingering, and propose a two-equation model for the scalar variance and its dissipation rate. Our analysis predicts the optimum range of viscosity contrasts that, for a given P'eclet number, maximizes interfacial area and minimizes mixing time. In the spirit of turbulence modeling, the proposed two-equation model permits upscaling dissipation due to fingering at unresolved scales.

Juanes, Ruben; Jha, Birendra; Cueto-Felgueroso, Luis

2011-11-01

336

Viscous fingering of miscible slices  

NASA Astrophysics Data System (ADS)

Viscous fingering of a miscible high viscosity slice of fluid displaced by a lower viscosity fluid is studied in porous media by direct numerical simulations of Darcy's law coupled to the evolution equation for the concentration of a solute controlling the viscosity of miscible solutions. In contrast with fingering between two semi-infinite regions, fingering of finite slices is a transient phenomenon due to the decrease in time of the viscosity ratio across the interface induced by fingering and dispersion processes. We show that fingering contributes transiently to the broadening of the peak in time by increasing its variance. A quantitative analysis of the asymptotic contribution of fingering to this variance is conducted as a function of the four relevant parameters of the problem, i.e., the log-mobility ratio R, the length of the slice l, the Péclet number Pe, and the ratio between transverse and axial dispersion coefficients ?. Relevance of the results is discussed in relation with transport of viscous samples in chromatographic columns and propagation of contaminants in porous media.

de Wit, A.; Bertho, Y.; Martin, M.

2005-05-01

337

Effect of NACA injection impeller on mixture distribution of double-row radial aircraft engine  

NASA Technical Reports Server (NTRS)

The NACA injection impeller was developed to improve the mixture distribution of aircraft engines by discharging the fuel from a centrifugal supercharger impeller and thus to promote a thorough mixing of fuel and charge air. Experiments with a double-row radial aircraft engine indicated that for the normal range of engine power the NACA injection impeller provided marked improvement in mixture distribution over the standard spray-bar injection system used in the same engine. The mixture distribution at cruising conditions was excellent; at 1200, 1500, and 1700 brake horsepower, the differences between the fuel-air ratios of the richest and the leanest cylinders were reduced to approximately one-third their former values.

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

1945-01-01

338

Experimental and numerical investigation of the unsteady flow field and tone generation in an isolated centrifugal fan impeller  

Microsoft Academic Search

In spite of a low circumferential Mach number the sound of isolated centrifugal fan impellers is sometimes dominated by distinctive tones at blade passing frequency (BPF) and integer multiples. This paper reports on an experimental and numerical investigation intended to unveil the tone generating mechanism. The sound spectra from three impellers operating at a large range of speed were measured

Daniel Wolfram; Thomas H. Carolus

2010-01-01

339

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

PubMed

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

Logan, R; Briens, L

2012-11-01

340

Effect of the impeller-sparger configuration over Trichoderma harzianum growth in four-phases cultures under constant dissolved oxygen  

Microsoft Academic Search

Three impeller-sparger configurations were used to evaluate the effect of different hydrodynamic conditions over fungal growth in rheologically complex cultures of Trichoderma harzianum using castor oil as sole carbon source. Three spargers (ring, sintered and 5-orifice) in combination with a turbine impeller system \\

J. A. Rocha-Valadez; E. Galindo; L. Serrano-Carreón

2000-01-01

341

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

NASA Technical Reports Server (NTRS)

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

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

1989-01-01

342

A multiple disk centrifugal pump as a blood flow device.  

PubMed

A multiple disk, shear force, valveless centrifugal pump was studied to determine its suitability as a blood flow device. A pulsatile version of the Tesla viscous flow turbine was designed by modifying the original steady flow pump concept to produce physiological pressures and flows with the aid of controlling circuitry. Pressures and flows from this pump were compared to a Harvard Apparatus pulsatile piston pump. Both pumps were connected to an artificial circulatory system. Frequency and systolic duration were varied over a range of physiological conditions for both pumps. The results indicated that the Tesla pump, operating in a pulsatile mode, is capable of producing physiologic pressures and flows similar to the Harvard pump and other pulsatile blood pumps. PMID:2312140

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

1990-02-01

343

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

344

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

NASA Technical Reports Server (NTRS)

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

Eckardt, D.

1978-01-01

345

Lagrangian chaos and mixing of viscous fluids  

Microsoft Academic Search

The authors describe a two-dimensional viscous fluid experiment. The experimental device is inspired by the technology of industrial mixers developed by the Kenics firm. A vessel, filled with a viscous fluid, is divided into two compartments by a plate. The surface of the fluid is marked by a thin film of paint, of a different colour in each compartment. The

E. Villermaux; J. P. Hulin

1990-01-01

346

IDENTIFICATION OF DAMPING: PART 1, VISCOUS DAMPING  

Microsoft Academic Search

Characterization of damping forces in a vibrating structure has long been an active area of research in structural dynamics. The most common approach is to use “viscous damping” where the instantaneous generalized velocities are the only relevant state variables that affect damping forces. However, viscous damping is by no means the only damping model within the scope of linear analysis.

S. Adhikari; J. Woodhouse

2001-01-01

347

The Design and Analysis of Helium Turbine Expander Impeller with a Given All-Over-Controlled Vortex Distribution  

NASA Astrophysics Data System (ADS)

To make the large-scale helium cryogenic system of fusion device EAST (experimental advanced super-conducting tokamak) run stably, as the core part, the helium turbine expander must meet the requirement of refrigeration capacity. However, previous designs were based on one dimension flow to determine the average fluid parameters and geometric parameters of impeller cross-sections, so that it could not describe real physical processes in the internal flow of the turbine expander. Therefore, based on the inverse proposition of streamline curvature method in the context of quasi-three-dimensional flows, the all-over-controlled vortex concept was adopted to design the impeller under specified condition. The wrap angle of the impeller blade and the whole flow distribution on the meridian plane were obtained; meanwhile the performance of the designed impeller was analyzed. Thus a new design method is proposed here for the inverse proposition of the helium turbine expander impeller.

Liu, Xiaodong; Fu, Bao; Zhuang, Ming

2014-03-01

348

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/100L to 0.040 g/100L 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

349

Magnetocaloric pump  

NASA Technical Reports Server (NTRS)

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

Brown, G. V.

1973-01-01

350

Some Studies on Viscous Fluids  

NASA Astrophysics Data System (ADS)

In this thesis, we study several issues involving incompressible viscous fluids with the slip boundary conditions and the motions of fluid-solid interactions. In the first part, we study the issue of the inviscid limit of the incompressible Navier-Stokes equations on the general smooth domains for completely slip boundary conditions. We verify an asymptotic expansion which involves a weak amplitude boundary layer with the same thickness as in the Prantle's theory. We improve the better regularity for the boundary layer and obtain the uniform Lp--estimates (3 < p ? 6) of the remainder. Then we improved these estimates to H 1--estimates. It is shown that the viscous solution converges to the solution of Euler equation in C([0, T]; H1(O)) as the viscosity tends to zero. In the second part, we consider the non-stationary problems of a class of non-Newtonian fluid which is a power law fluid with p > 3nn+2 in the half space with slip boundary conditions. We present the local pressure estimate with the Navier's slip boundary conditions. Using these estimates and an Linfinity -- truncation method, we can obtain that this system has at least one required weak solution. Finally, we investigate the motion of a general form rigid body with smooth boundary by an incompressible perfect fluid occupying R3 . Due to the domain occupied by the fluid depending on the time, this problem can be transformed into a new systems of the fluid in a fixed domain by the frame attached with the body. With the aid of Kato-Lai's theory, we construct a sequence of successive solutions to this problem in some unform time interval. Then by a fixed point argument, we have proved that the existence, uniqueness and persistence of the regularity for the solutions of original fluid-structure interaction problem.

Zang, Aibin

351

Failed repeated thrombolysis requiring left ventricular assist device pump exchange.  

PubMed

A 51-year-old male with untreated hepatitis C infection, cirrhosis, and dilated cardiomyopathy with a HeartMate II LVAD presented with right heart failure and cardiogenic shock, INR of 7, hemolysis, and renal failure. Acute LVAD thrombosis was suspected. Alteplase was injected into the inflow cannula of the LVAD with little effect. Intravenous alteplase was given but failed to restore an adequate pump output, resulting in the need for emergency pump exchange. The patient had an uncomplicated postoperative recovery and was discharged uneventfully. Inspection of the pump identified a thrombus wedged between the spines of the impeller. Our case highlights the challenges in managing pump thrombosis which is often resistant to thrombolysis and may instead rely upon prompt surgical intervention to be resolved. PMID:22718366

Tang, Gilbert H L; Kim, Michael C; Pinney, Sean P; Anyanwu, Anelechi C

2013-05-01

352

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

353

Remotely maintained waste transfer pump  

SciTech Connect

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

Eargle, J.C.

1990-01-01

354

Remotely maintained waste transfer pump  

SciTech Connect

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

Eargle, J.C.

1990-12-31

355

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

PubMed

To provide hemodynamic support to patients with a failing single ventricle, we are developing a percutaneously inserted, magnetically levitated axial flow blood pump designed to augment pressure in the cavopulmonary circulation. The device is designed to serve as a bridge-to-transplant, bridge-to-recovery, bridge-to-hemodynamic stability, or bridge-to-surgical reconstruction. This study evaluated the hydraulic performance of three blood pump prototypes (a four-bladed impeller, a three-bladed impeller, and a three-bladed impeller with a four-bladed diffuser) whose designs evolved from previous design optimization phases. Each prototype included the same geometric protective cage of filaments, which stabilize the rotor within the housing and protect the housing wall from the rotating blades. All prototypes delivered pressure rises over a range of flow rates and rotational speeds that would be sufficient to augment hemodynamic conditions in the cavopulmonary circulation. The four-bladed impeller outperformed the two remaining prototypes by >40%; this design was able to generate a pressure rise of 4-28 mm Hg for flow rates of 0.5-10 L/min at rotational speeds of 4,000-7,000 RPM. Successful development of this blood pump will provide clinicians with a feasible therapeutic option for mechanically supporting the failing Fontan. PMID:20051837

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

2010-01-01

356

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

357

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

358

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

PubMed

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

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

2013-11-01

359

Study on the methods of determining main geometric parameters of centrifugal fan impeller  

Microsoft Academic Search

Because of the complexity of internal flow characteristics of centrifugal fan, a set of wholly mature design methods of impeller theory do not exist at the present time. The paper tries to investigate and analyze the internal relations between a large number of existing aerodynamic sketches and performance parameters of centrifugal fans by means of statistical method and finds regularity.

Yan Gui; Pingyuan Xi

2010-01-01

360

Stress Intensity Factors in a Rotating Impeller Containing Semi-Elliptical Surface Crack  

Microsoft Academic Search

Rotating compressors have been used for many years to compress gas in the oil and gas industries. Fatigue surface cracks at the stress concentration regions are the most common damages that cause the catastrophic failure of impellers. Stress analysis of surface cracks are needed for reliable prediction of their crack growth rates and fracture strengths. In this paper the problem

Mohammad Rahim Nami; Hadi Eskandari

2012-01-01

361

Impelling and Inhibiting Forces in the Perpetration of Intimate Partner Violence  

Microsoft Academic Search

The huge corpus of research identifying risk factors for intimate partner violence (IPV) has outpaced theoretical models explaining how these risk factors combine to exert their effects. This report presents a 2-stage process model investigating how a previously nonviolent interaction between intimate partners escalates to IPV. The first stage examines whether at least one partner experiences strong violence-impelling forces, which

Eli J. Finkel

2007-01-01

362

Experimental study of hydrodynamic propulsion of a medical device with a spiral ribbed impeller  

Microsoft Academic Search

In order to minimize injury during a medical treatment using a low invasive sliding device, loss of cells and tissues due to wear against the device must be prevented by maintaining good lubrication condition. For this purpose, a new medical device with a spiral ribbed impeller has been presented. This paper shows the potentials and problems of the proposed mechanism

Kiyoshi Yoshinaka; Naohide Tomita; Ken Ikeuchi

1998-01-01

363

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

364

An investigation of unsteady impeller-diffuser interactions in a centrifugal compressor  

Microsoft Academic Search

An investigation of steady and unsteady flow phenomena in centrifugal compressors has been performed. In particular, the effect of vaned diffuser geometry on the compressor unsteady aerodynamics has been considered, with particular emphasis on the diffuser vane unsteady loading generated by the impeller circumferentially nonuniform flowfield. A series of experiments was performed in the Purdue Centrifugal Compressor Facility to quantify

William Barry Bryan

1991-01-01

365

Magnetically suspended centrifugal blood pump with an axially levitated motor.  

PubMed

The longevity of a rotary blood pump is mainly determined by the durability of its wearing mechanical parts such as bearings and seals. Magnetic suspension techniques can be used to eliminate these mechanical parts altogether. This article describes a magnetically suspended centrifugal blood pump using an axially levitated motor. The motor comprises an upper stator, a bottom stator, and a levitated rotor-impeller between the stators. The upper stator has permanent magnets to generate an attractive axial bias force on the rotor and electric magnets to control the inclination of the rotor. The bottom stator has electric magnets to generate attractive forces and rotating torque to control the axial displacement and rotation of the rotor. The radial displacement of the rotor is restricted by passive stability. A shrouded impeller is integrated within the rotor. The performance of the magnetic suspension and pump were evaluated in a closed mock loop circuit filled with water. The maximum amplitude of the rotor displacement in the axial direction was only 0.06 mm. The maximum possible rotational speed during levitation was 1,600 rpm. The maximum pressure head and flow rate were 120 mm Hg and 7 L/min, respectively. The pump shows promise as a ventricular assist device. PMID:12823418

Masuzawa, Toru; Ezoe, Shiroh; Kato, Tsuyoshi; Okada, Yohji

2003-07-01

366

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

367

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

368

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

369

Identification and classification of physiologically significant pumping states in an implantable rotary blood pump.  

PubMed

In a clinical setting it is necessary to control the speed of rotary blood pumps used as left ventricular assist devices to prevent possible severe complications associated with over- or underpumping. The hypothesis is that by using only the noninvasive measure of instantaneous pump impeller speed to assess flow dynamics, it is possible to detect physiologically significant pumping states (without the need for additional implantable sensors). By varying pump speed in an animal model, five such states were identified: regurgitant pump flow, ventricular ejection (VE), nonopening of the aortic valve over the cardiac cycle (ANO), and partial collapse (intermittent and continuous) of the ventricle wall (PVC-I and PVC-C). These states are described in detail and a strategy for their noninvasive detection has been developed and validated using (n = 6) ex vivo porcine experiments. Employing a classification and regression tree, the strategy was able to detect pumping states with a high degree of sensitivity and specificity: state VE-99.2/100.0% (sensitivity/specificity); state ANO-100.0/100.0%; state PVC-I- 95.7/91.2%; state PVC-C-69.7/98.7%. With a simplified binary scheme differentiating suction (PVC-I, PVC-C) and nonsuction (VE, ANO) states, both such states were detected with 100% sensitivity. PMID:16934095

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

2006-09-01

370

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

371

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

372

Cavitation performance improvement of high specific speed mixed-flow pump  

NASA Astrophysics Data System (ADS)

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

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

2012-11-01

373

Effect of the outlet angle ? 2 on the characteristics of low specific-speed centrifugal pumps  

Microsoft Academic Search

Conclusions An experimental check of various low specific-speed pumps showed that on changing the geometry of the vaning of the impeller, in conformity with the recommendations [1], the main feature of which is an increase of the outlet angles of the vanes to values 90°=ß2=130° and installation of short intermediate vanes in the passages between the main vanes, the head

V. I. Veselov

1982-01-01

374

Magnetocaloric Pump.  

National Technical Information Service (NTIS)

A pump for use with cryogenic liquids is described. The pump is composed of a vessel having outlet and inlet valves which may be one way check valves or solenoid types operated in timed sequence from a timer. The vessel is located in a container filled wi...

G. V. Brown

1972-01-01

375

Ferroelectric Pump  

NASA Technical Reports Server (NTRS)

A ferroelectric pump has one or more variable volume pumping chambers internal to a housing. Each chamber has at least one wall comprising a dome shaped internally prestressed ferroelectric actuator having a curvature and a dome height that varies with an electric voltage applied between an inside and outside surface of the actuator. A pumped medium flows into and out of each pumping chamber in response to displacement of the ferroelectric actuator. The ferroelectric actuator is mounted within each wall and isolates each ferroelectric actuator from the pumped medium, supplies a path for voltage to be applied to each ferroelectric actuator, and provides for positive containment of each ferroelectric actuator while allowing displacement of the entirety of each ferroelectric actuator in response to the applied voltage.

Jalink, Antony, Jr. (Inventor); Hellbaum, Richard F. (Inventor); Rohrbach, Wayne W. (Inventor)

2000-01-01

376

Small centrifugal pumps for low-thrust rocket engines  

NASA Technical Reports Server (NTRS)

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

Furst, R. B.

1986-01-01

377

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

Microsoft Academic Search

Capillary instability of a liquid cylinder immersed in another liquid is analyzed using viscous potential flow. An effect of viscosity on the irrotational motion may be introduced by evaluating the viscous normal stress at the liquid-liquid interface on the irrotational motions. In a second approximation, the explicit effects of the discontinuity of the shear stress and tangential component of velocity

J. Wang; D. D. Joseph; T. Funada

2005-01-01

378

Reduced-Order Models of Unsteady Viscous Flows in Turbomachinery Using Viscous-Inviscid Coupling  

Microsoft Academic Search

The proper orthogonal decomposition technique is applied in the frequency domain to obtain a reduced-order model of the flow in a turbomachinery cascade. The flow is described by an inviscid-viscous interaction model where the inviscid part is described by the full potential equation and the viscous part is described by an integral boundary layer model. The fully nonlinear steady flow

B. I. Epureanu; K. C. Hall; E. H. Dowell

2001-01-01

379

REDUCED-ORDER MODELS OF UNSTEADY VISCOUS FLOWS IN TURBOMACHINERY USING VISCOUS–INVISCID COUPLING  

Microsoft Academic Search

The proper orthogonal decomposition technique is applied in the frequency domain to obtain a reduced-order model of the flow in a turbomachinery cascade. The flow is described by an inviscid–viscous interaction model where the inviscid part is described by the full potential equation and the viscous part is described by an integral boundary layer model. The fully nonlinear steady flow

B. I. EPUREANU; K. C. HALL; E. H. DOWELL

2001-01-01

380

Formation of impeller-like helical DNA-silica complexes by polyamines induced chiral packing.  

PubMed

The helicity of DNA and its long-range chiral packing are widespread phenomena; however, the packing mechanism remains poorly understood both in vivo and in vitro. Here, we report the extraordinary DNA chiral self-assembly by silica mineralization, together with circular dichroism measurements and electron microscopy studies on the structure and morphology of the products. Mg(2+) ion and diethylenetriamine were found to induce right- and left-handed chiral DNA packing with two-dimensional-square p4mm mesostructures, respectively, to give corresponding enantiomeric impeller-like helical DNA-silica complexes. Moreover, formation of macroscopic impeller-like helical architectures depends on the types of polyamines and co-structure-directing agents and pH values of reaction solution. It has been suggested that interaction strength between negatively charged DNA phosphate strands and positively charged counterions may be the key factor for the induction of DNA packing handedness. PMID:24098845

Liu, Ben; Han, Lu; Che, Shunai

2012-10-01

381

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

PubMed

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

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

2010-06-01

382

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

PubMed

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

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

1997-01-01

383

Formation of impeller-like helical DNA-silica complexes by polyamines induced chiral packing  

PubMed Central

The helicity of DNA and its long-range chiral packing are widespread phenomena; however, the packing mechanism remains poorly understood both in vivo and in vitro. Here, we report the extraordinary DNA chiral self-assembly by silica mineralization, together with circular dichroism measurements and electron microscopy studies on the structure and morphology of the products. Mg2+ ion and diethylenetriamine were found to induce right- and left-handed chiral DNA packing with two-dimensional-square p4mm mesostructures, respectively, to give corresponding enantiomeric impeller-like helical DNA–silica complexes. Moreover, formation of macroscopic impeller-like helical architectures depends on the types of polyamines and co-structure-directing agents and pH values of reaction solution. It has been suggested that interaction strength between negatively charged DNA phosphate strands and positively charged counterions may be the key factor for the induction of DNA packing handedness.

Liu, Ben; Han, Lu; Che, Shunai

2012-01-01

384

Wind-Tunnel Tests of a Modified Koppers Aeromatic Impeller-Generator Combination, TED No. NACA ARR 2901  

NASA Technical Reports Server (NTRS)

An investigation was conducted in the 6- by 6-foot test section of the Langley stability tunnel on a modified Koppers Aeromatic wind-driven impeller-generator combination. This investigation consisted of a few fixed pitch tests and a series of variable pitch tests, The fixed pitch tests indicated that the impeller should operate between the blade-pitch angles of 20 and 32deg at the specified output of 11.7 kilowatts in order to remain within the specified rotational speed of from 5000 to 8000 rpm for airspeeds of from 130 to 175 miles per hour. The requirement that the impeller maintain rotational speeds of - between 5000 and 8000 rpm as the impeller output varied from 0 to ll.7 kilowatts at airspeeds of from 130 to 175 miles per hour was not met at any tims during the variable pitch tests. The main difficulty seemed to be the inability of the impeller blades to change blade-pitch angle smoothly and quickly as load conditions varied. There was some indication that the vibration normally occurring on an airplane might cause the impeller to operate satisfactorily.

Queijo, M. J.

1946-01-01

385

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

386

Modeling gas-liquid head performance of electrical submersible pumps  

NASA Astrophysics Data System (ADS)

The objectives of this study are to develop a simple and accurate theoretical model and to implement the model into a computational tool to predict Electrical Submersible Pumps (ESP) head performance under two-phase flow conditions. A new two-phase model including a set of one-dimensional mass and momentum balance equations was developed. The derived gas-liquid momentum equations along pump channels has improved Sachdeva (1992, 1994)'s model in petroleum industry and generalized Minemura (1998)'s model in nuclear industry. The resulting pressure ODE for frictionless incompressible single-phase flow is consistent with the pump Euler equation. In the two-phase momentum equations, new models for wall frictional losses for each phase, through using gas-liquid stratified assumption and existing correlations for impeller rotating effect, channel curvature effect, and channel cross section effect, have been proposed. New equations for radius of curvature along ESP channels, used in the curvature effect calculation, have been derived. A new shock loss model incorporating rotational speeds has been developed. A new correlation for drag coefficient and interfacial characteristic length effects has been obtained through fitting the model results with experimental data. An algorithm to solve the model equations has been developed and implemented. The model predicts pressure and void fraction distributions along impellers and diffusers and can also be used to predict the pump head performance curve under different fluid properties, pump intake conditions, and rotational speeds. The new two-phase model is validated with air-water experimental data. Results show the model provides a very good prediction for pump head performance under different gas flow rates, liquid flow rates, and different intake pressures. The new model is capable of predicting surging and gas lock conditions.

Sun, Datong

387

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

388

Impelling and inhibitory forces in aggression: sex-of-target and relationship effects.  

PubMed

The finding of symmetry in intimate partner aggression is now generally accepted, but the convergence of male and female rates in these relationships remains unexplained. From qualitative analysis of male and female focus group discussions, we identified factors believed to influence the expression of aggression toward targets differing in sex and degree of intimacy. These factors were then used to construct a questionnaire in which 355 respondents indicated the applicability of the items to conflicts with a partner, a same-sex friend, and an opposite-sex friend. Principal component analysis revealed a clear two-factor structure of impelling forces (tending to provoke or initiate aggression) and inhibitory forces (tending to suppress or diminish the likelihood of aggression). Participants' scores on scales derived from these two factors were used in the subsequent analyses. Men reported lower inhibition and greater impulsion toward same-sex friends than to female friends and partners, who did not differ significantly from one another. Women showed lower inhibition to male targets, regardless of relationship, than to a female target. However, women rated their male partners as significantly higher on impelling forces than their male friends, who in turn were rated significantly higher than female friends. The results are broadly consistent with a sex-of-target effect corresponding to a chivalry norm held by both sexes that inhibits the expression of aggression toward women. The reasons why women are especially impelled to aggression by intimate partners are explored. Disaggregating the dynamics of interpersonal conflict into impelling and inhibitory components may prove useful in understanding and treating dispute escalation and resolution. PMID:21156694

Davidovic, Anna; Bell, Kurtis; Ferguson, Colin; Gorski, Elizabeth; Campbell, Anne

2011-10-01

389

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

Microsoft Academic Search

The gas–liquid mass transfer coefficient KLa 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

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

2001-01-01

390

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

PubMed

A magnetically suspended axial flow blood pump is studied experimentally in this article. The pump casing enclosed a three-blade straightener, a two-blade impeller shrouded by a permanent magnet-embedded cylinder, and a three-blade diffuser. The internal flow fields were simulated earlier using computational fluid dynamics (CFD), and the pump characteristic curves were determined. The simulation results showed that the internal flow field was basically streamlined, except the diffuser region. Particle image velocimetry (PIV) measurement of the 1:1 pump model was conducted to validate the CFD result. In order to ensure the optical access, an acrylic prototype was fabricated with the impeller driven by a servomotor instead, as the magnet is opaque. In addition to the transparent model, the blood analog fluid with the refractive index close to that of acrylic was used to avoid refraction. According to the CFD results, the axial flow blood pump could generate adequate pressure head at the rotating speed of 9500rpm and flow rate of 5L/min, and the same flow condition was applied during the PIV measurement. Through the comparisons, it was found that the experimental results were close to those obtained by CFD and had thus validated the CFD model, which could complement the limitation of the measurement in assessing the more detailed flow fields of the axial flow pump. PMID:22040356

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

2012-04-01

391

Sugarcane bagasse enzymatic hydrolysis: rheological data as criteria for impeller selection.  

PubMed

The aim of this work was to select an efficient impeller to be used in a stirred reactor for the enzymatic hydrolysis of sugar cane bagasse. All experiments utilized 100 g (dry weight)/l of steam-pretreated bagasse, which is utilized in Brazil for cattle feed. The process was studied with respect to the rheological behavior of the biomass hydrolysate and the enzymatic conversion of the bagasse polysaccharides. These parameters were applied to model the power required for an impeller to operate at pilot scale (100 l) using empirical correlations according to Nagata [16]. Hydrolysis experiments were carried out using a blend of cellulases, ?-glucosidase, and xylanases produced in our laboratory by Trichoderma reesei RUT C30 and Aspergillus awamori. Hydrolyses were performed with an enzyme load of 10 FPU/g (dry weight) of bagasse over 36 h with periodic sampling for the measurement of viscosity and the concentration of glucose and reducing sugars. The mixture presented pseudoplastic behavior. This rheological model allowed for a performance comparison to be made between flat-blade disk (Rushton turbine) and pitched-blade (45°) impellers. The simulation showed that the pitched blade consumed tenfold less energy than the flat-blade disk turbine. The resulting sugar syrups contained 22 g/l of glucose, which corresponded to 45% cellulose conversion. PMID:20844924

Pereira, Leonardo Tupi Caldas; Pereira, Lucas Tupi Caldas; Teixeira, Ricardo Sposina Sobral; Bon, Elba Pinto da Silva; Freitas, Suely Pereira

2011-08-01

392

Hydraulic Pumps and Hydraulic Equipment at Low Temperatures.  

National Technical Information Service (NTIS)

The ambient temperature may be -40 - -60 deg C in arctic conditions. This causes hardening and shrinkage of seals, deterioration of the suction ability of hydraulic pumps, brittleness in metals and more viscous hydraulic fluids. This may result in oil lea...

R. Soudunsaari A. Lehto

1987-01-01

393

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

394

Computational fluid dynamics-based hydraulic and hemolytic analyses of a novel left ventricular assist blood pump.  

PubMed

The advent of various technologies has allowed mechanical blood pumps to become more reliable and versatile in recent decades. In our study group, a novel structure of axial flow blood pump was developed for assisting the left ventricle. The design point of the left ventricular assist blood pump 25 (LAP-25) was chosen at 4 Lpm with 100 mm Hg according to our clinical practice. Computational fluid dynamics was used to design and analyze the performance of the LAP-25. In order to obtain a required hydraulic performance and a satisfactory hemolytic property in the LAP-25 of a smaller size, a novel structure was developed including an integrated shroud impeller, a streamlined impeller hub, and main impeller blades with splitter blades; furthermore, tandem cascades were introduced in designing the diffuser. The results of numerical simulation show the LAP-25 can generate flow rates of 3-5 Lpm at rotational speeds of 8500-10,500 rpm, producing pressure rises of 27.5-148.3 mm Hg with hydraulic efficiency points ranging from 13.4 to 27.5%. Moreover, the fluid field and the hemolytic property of the LAP-25 were estimated, and the mean hemolysis index of the pump was 0.0895% with Heuser's estimated model. In conclusion, the design of the LAP-25 shows an acceptable result. PMID:21517911

Yang, Xiao-Chen; Zhang, Yan; Gui, Xing-Min; Hu, Sheng-Shou

2011-10-01

395

Automated non-invasive detection of pumping states in an implantable rotary blood pump.  

PubMed

With respect to rotary blood pumps used as left ventricular assist devices (LVADs), it is clinically important to control pump flow to avoid complications associated with over-or under-pumping of the native heart. By employing only the non-invasive observer of instantaneous pump impeller speed to assess flow dynamics, a number of physiologically significant pumping states may be detected. Based on a number of acute animal experiments, five such states were identified: regurgitant pump flow (PR), ventricular ejection (VE), non-opening of the aortic valve (ANO), and partial collapse (intermittent and continuous) of the ventricle wall (PVC-I and PVC-C). Two broader states, normal (corresponding to VE, ANO) and suction (corresponding to PVC-I, PVC-C) were readily discernable in clinical data from human patients implanted with LVADs. Based on data from both the animal experiments (N=6) and the human patients (N=10), a strategy for the automated non-invasive detection of significant pumping states has been developed and validated. Employing a classification and regression tree (CART), this system detects pumping states with a high degree of accuracy: state VE -87.5/100.0% (sensitivity/specificity); state ANO - 98.1/92.5%; state PVC-I - 90.0/90.2%; state PVC-C - 61.2/98.0%. With a simplified binary scheme differentiating suction and normal states, both states were detected without error in data from the animal experiments, and with a sensitivity/specificity, for detecting suction, of 99.2/98.3% in the human patient data. PMID:17946699

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

2006-01-01

396

Electrokinetic pump  

SciTech Connect

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

Patel, Kamlesh D. (Dublin, CA)

2007-11-20

397

Preliminary validation of a new magnetic wireless blood pump.  

PubMed

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

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

2013-10-01

398

Dynamic wetting of viscous and viscoelastic fluids  

NASA Astrophysics Data System (ADS)

Dynamic wetting poses a complex fluid mechanical problem of both fundamental and technological importance. This complexity arises because the fundamental geometry of the wedge-like region near the moving contact line requires that fluid elements experience ever increasing deformation rates as they pass into and out of that region. Thus, somewhere in the flow field, relaxation modes caused by segmental and chain motions in a viscous polymeric fluid may be unable to relax, leading to nonlinear stresses and possible changes in the shape of the deformable free surface. In this thesis, we investigate the wetting behavior of model viscoelastic fluids, Boger fluids, and the viscous oligomeric fluids which are the base solvents in these Boger fluids. We determine that the dominant relaxation mode in Boger fluids has only small effects on both viscous bending and dynamic contact angles even approaching the air entrainment limit. A lubrication analysis, used to examine the impact of the linear elasticity due to dominant relaxation mode, also shows only small effects on the interface curvature and on the dynamic contact angle. The viscous oligomeric base fluids, which have only very short relaxation times, also show deviations from the viscous bending that a Newtonian fluid exhibits near the contact line. Our experiments prove that these deviations do not arise due to the interactions between the fluid and the solid surface. It is very possible that this behavior arises from the influence of the non-Newtonian behavior at a small length scale on the Newtonian hydrodynamics at larger distances from the contact line. Finally, a new relaxation regime has been discovered as the final static contact angle is approached in the spontaneous relaxation of the viscous fluids with non-zero static contact angles. This new regime may be due to slow rearrangements of the polymeric molecules altering the static force balance at the contact line.

Wei, Yuli

399

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

400

Bounce solutions in viscous fluid cosmology  

NASA Astrophysics Data System (ADS)

We investigate the bounce cosmology induced by inhomogeneous viscous fluids in FRW space-time (non necessarily flat), taking into account the early-time acceleration after the bounce. Different forms for the scale factor and several examples of fluids will be considered. We also analyze the relation between bounce and finite-time singularities and between the corresponding fluids realizing this scenarios. In the last part of the work, the study is extended to the framework of f( R)-modified gravity, where the modification of gravity may also be considered as an effective (viscous) fluid producing the bounce.

Myrzakulov, Ratbay; Sebastiani, Lorenzo

2014-07-01

401

Asthenospheric Mantle Flow by Viscous Fingering Instabilities  

NASA Astrophysics Data System (ADS)

We investigate mantle flow in the oceanic asthenospheric by lateral flow of viscous fingering instabilities. In this model, the asthenosphere acts as a channel for mantle flow from an off axis source to the spreading center, perhaps on a global scale. This phenomenon may be observed by linear chains of intraplate volcanism on young seafloor near ridge axes where we suggest asthenospheric fingering material may induce melting beneath thin lithosphere. We perform laboratory fluid experiments of viscous fingering in miscible high viscosity fluids which flow radially through a Hele-Shaw cell. Fluids with low Reynolds number provide scaling to the Earth's mantle where viscous forces dominate and chemical diffusion is slow. We find that viscous fingers are well developed in this geodynamic regime with the fingering wavelength (? f) controlled by viscous dissipation in the displaced fluid. Fingering patterns approach a constant wavelength after an initial growth phase and depend on plate spacing (B) as {? f} = 12B. We also observe the formation of a film layer surrounding low viscosity fingers as they propagate. When density differences exist between the two fluids, the film layer above the finger is higher density, inherently unstable, and begins to downwell as a Rayleigh-Taylor instabilities observed in shadowgraphs as white striations within each finger that are linear and regularly spaced. We find the wavelength of striations ({? st}) scales with finger growth as {? st}= 4 {? f}. The application of a moving surface plate is observed to align all fingers in a linear direction parallel to plate motion both downstream and upstream. These experiments suggest that mantle flow in the Earth's asthenosphere may be exhibit instabilities governed by viscous fingering if sufficient viscosity variations are present between the depleted asthenosphere and the introduction of low viscosity, volatile rich, off-axis plume material. This viscous fingering model predicts a compositional difference at the base of the lithosphere with volatile rich or partially melted low viscosity material below a rigid dry depleted lithosphere above. Low seismic velocity observations from global tomography in the SE Pacific and regional studies of body wave tomography in the western US indicate alternating bands of low and high seismic velocities at sublithospheric depths parallel to plate motion which is consistent with a model for viscous fingering in the Earth's mantle beneath both oceanic and continental plates.

Weeraratne, D. S.; Parmentier, E.

2010-12-01

402

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

PubMed

Rotary blood pumps have been researched as implantable ventricular assist devices for years. To further reduce the complex of implanted axial pumps, the authors proposed a new concept of intraaortic axial pump, termed previously as "dynamic aortic valve (DAV)". Instead of being driven by an intraaortic micro-electric motor, it was powered by a magnetic field from outside of body. To ensure the perfusion of coronary artery, the axial flow pump is to be implanted in the position of aortic valve. It could serve as either a blood pump or a mechanical valve depending on the power input. This research tested the feasibility of the new concept in model study. A column, made from permanent magnet, is jointed to an impeller in a concentric way to form a "rotor-impeller". Supported by a hanging shaft cantilevered in the center of a rigid cage, the rotor-impeller can be turned by the magnetic field in the surrounding space. In the present prototype, the rotor is 8 mm in diameter and 15 mm in length, the impeller has 3 vanes with an outer diameter of 18 mm. The supporting cage is 22 mm in outer diameter and 20 mm in length. When tested, the DAV prototype is inserted into the tube of a mock circuit. The alternative magnetic field is produced by a rotating magnet placed side by side with the rotor-impeller at a distance of 30 mm. Once the alternative magnetic field is presented in the surrounding space, the DAV starts to turn, leading to a pressure difference and liquid flow in the tube. The flow rate or pressure difference is proportioned to rotary speed. At the maximal output of hydraulic power, the flow rate reached 5 L/min against an afterload of 100 mmHg. The maximal pressure difference generated by DAV at a rotation rate of 12600 r/min was 147 mmHg. The preliminary results demonstrated the feasibility of "DAV", further research on this concept is justifiable. PMID:18726438

Li, G; Zhao, H; Hu, S; Zhu, X; Wu, Q; Ren, B; Ma, W

2001-04-01

403

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

NASA Astrophysics Data System (ADS)

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

Dou, H. S.; Jiang, W.

2013-12-01

404

Optimal hydraulic design of new-type shaft tubular pumping system  

NASA Astrophysics Data System (ADS)

Based on the characteristics of large flow rate, low-head, short annual operation time and high reliability of city flood-control pumping stations, a new-type shaft tubular pumping system featuring shaft suction box, siphon-type discharge passage with vacuum breaker as cutoff device was put forward, which possesses such advantages as simpler structure, reliable cutoff and higher energy performance. According to the design parameters of a city flood control pumping station, a numerical computation model was set up including shaft-type suction box, siphon-type discharge passage, pump impeller and guide vanes. By using commercial CFD software Fluent, RNG ?-epsilon turbulence model was adopted to close the three-dimensional time-averaged incompressible N-S equations. After completing optimal hydraulic design of shaft-type suction box, and keeping the parameters of total length, maximum width and outlet section unchanged, siphon-type discharge passages of three hump locations and three hump heights were designed and numerical analysis on the 9 hydraulic design schemes of pumping system were proceeded. The computational results show that the changing of hump locations and hump heights directly affects the internal flow patterns of discharge passages and hydraulic performances of the system, and when hump is located 3.66D from the inlet section and hump height is about 0.65D (D is the diameter of pump impeller), the new-type shaft tubular pumping system achieves better energy performances. A pumping system model test of the optimal designed scheme was carried out. The result shows that the highest pumping system efficiency reaches 75.96%, and when at design head of 1.15m the flow rate and system efficiency were 0.304m3/s and 63.10%, respectively. Thus, the validity of optimal design method was verified by the model test, and a solid foundation was laid for the application and extension of the new-type shaft tubular pumping system.

Zhu, H. G.; Zhang, R. T.; Zhou, J. R.

2012-11-01

405

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

406

Viscous-fingering minimization in uniform three-dimensional porous media.  

PubMed

In this paper, we consider a radial displacement of a viscous fluid by another one of much lower viscosity through a three-dimensional uniform porous medium. It is well known that when a less viscous fluid is pumped at a constant injection rate, very complex interfacial patterns are formed. The control and eventual suppression of these instabilities are relevant to a large number of areas in science and technology. Here, we use a variational approach to search for an analytical form of an optimal flow rate so that the interface between two almost neutrally buoyant fluids grows, but the emergence of interfacial disturbances is minimized. We find a closed analytical solution for the ideal flow rate which surprisingly does not depend on either the properties of the fluids or the permeability of the porous medium. PMID:24483557

Dias, Eduardo O

2013-12-01

407

Viscous and impact demagnetization of Martian crust  

Microsoft Academic Search

Magnetization of Martian crust has been modified by impact-induced shock waves and viscous decay since the cessation of the core dynamo of Mars at around 4 Gyr ago. Thermal evolution models of Mars suggest that the potentially magnetic layer was about 85 km thick during the active period of the core dynamo, assuming magnetite as the major magnetic carrier. The

Hosein Shahnas; Jafar Arkani-Hamed

2007-01-01

408

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

409

Dispersive hydrodynamics in viscous fluid conduits.  

PubMed

The evolution of the interface separating a conduit of light, viscous fluid rising buoyantly through a heavy, more viscous, exterior fluid at small Reynolds numbers is governed by the interplay between nonlinearity and dispersion. Previous authors have proposed an approximate model equation based on physical arguments, but a precise theoretical treatment for this two-fluid system with a free boundary is lacking. Here, a derivation of the interfacial equation via a multiple scales, perturbation technique is presented. Perturbations about a state of vertically uniform, laminar conduit flow are considered in the context of the Navier-Stokes equations with appropriate boundary conditions. The ratio of interior to exterior viscosities is the small parameter used in the asymptotic analysis, which leads systematically to a maximal balance between buoyancy driven, nonlinear self-steepening and viscous, interfacial stress induced, nonlinear dispersion. This results in a scalar, nonlinear partial differential equation describing large amplitude dynamics of the cross-sectional area of the intrusive fluid conduit, in agreement with previous derivations. The leading order behavior of the two-fluid system is completely characterized in terms of the interfacial dynamics. The regime of model validity is characterized and shown to agree with previous experimental studies. Viscous fluid conduits provide a robust setting for the study of nonlinear, dispersive wave phenomena. PMID:24032933

Lowman, N K; Hoefer, M A

2013-08-01

410

Dispersive hydrodynamics in viscous fluid conduits  

NASA Astrophysics Data System (ADS)

The evolution of the interface separating a conduit of light, viscous fluid rising buoyantly through a heavy, more viscous, exterior fluid at small Reynolds numbers is governed by the interplay between nonlinearity and dispersion. Previous authors have proposed an approximate model equation based on physical arguments, but a precise theoretical treatment for this two-fluid system with a free boundary is lacking. Here, a derivation of the interfacial equation via a multiple scales, perturbation technique is presented. Perturbations about a state of vertically uniform, laminar conduit flow are considered in the context of the Navier-Stokes equations with appropriate boundary conditions. The ratio of interior to exterior viscosities is the small parameter used in the asymptotic analysis, which leads systematically to a maximal balance between buoyancy driven, nonlinear self-steepening and viscous, interfacial stress induced, nonlinear dispersion. This results in a scalar, nonlinear partial differential equation describing large amplitude dynamics of the cross-sectional area of the intrusive fluid conduit, in agreement with previous derivations. The leading order behavior of the two-fluid system is completely characterized in terms of the interfacial dynamics. The regime of model validity is characterized and shown to agree with previous experimental studies. Viscous fluid conduits provide a robust setting for the study of nonlinear, dispersive wave phenomena.

Lowman, N. K.; Hoefer, M. A.

2013-08-01

411

Dilepton production in schematic causal viscous hydrodynamics  

SciTech Connect

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{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 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 [Cyclotron Institute, Texas A and M University, College Station, Texas 77843-3366 (United States); Han, Kyong Chol; Ko, Che Ming [Cyclotron Institute and Department of Physics and Astronomy, Texas A and M University, College Station, Texas 77843-3366 (United States)

2011-02-15

412

Can altruism evolve in purely viscous populations?  

Microsoft Academic Search

Summary  Limited dispersal is often thought to facilitate the evolution of altruism by increasing the degree of relatedness among interacting individuals. Limited dispersal can have additional effects, however, such as local population regulation, that inhibits the evolution of altruism. Many models of structured populations assume that a viscous stage of the life cycle alternates with a global mixing stage, which allows

D. S. Wilson; G. B. Pollock; L. A. Dugatkin

1992-01-01

413

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

414

Nonlinear stability of viscous shock waves  

Microsoft Academic Search

this paper we study the large time asymptotic stability of solutions for systems ofnonlinear viscous conservation laws of the form(1:1)u t + f(u) x = u xx ; x 2 R I; t ? 0 ; u 2 R Iu(\\\\Delta; 0) = u 0 (\\\\Delta) :We treat systems which are strictly hyperbolic. Such systems possess a smooth travellingwave solution, which

Anders Szepessy; Zhouping Xin

1993-01-01

415

Fluid mixing apparatus for submersible pumps  

SciTech Connect

A well pump assembly for pumping production fluid, is described comprising in combination: a centrifugal in combination: a centrifugal submersible pump having an intake on its lower end and adapted to be secured to a string of tubing; an electrical motor located below the pump for driving the pump; a jacket enclosing the pump intake and motor, extending from above the intake to a point below the motor and adapted to extend into the production fluid; a cutting fluid conduit adapted to extend from the surface for delivering a cutting fluid from the surface, the cutting fluid conduit terminating below the motor and in fluid communication with a cross-over member; cutting fluid passage means in the cross-over member for receiving the cutting fluid from the cutting fluid conduit and for directing the cutting fluid upward; and production fluid passage means in the cross-over member adapted to be in communication with the production fluid for directing the production fluid upward. The cutting fluid passage means and the production fluid passage means crossing each other, with one of the passage means leading upward and outward and the other leading upward and inward, causing the fluids to mix above the cross-over member to facilitate pumping of the production fluid when highly viscous.

Vandevier, J.E.; Doty, L.E.

1988-06-07

416

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

417

The Three Regimes of Miscible Viscous Fingering  

NASA Astrophysics Data System (ADS)

Viscous fingering, the hydrodynamic instability that sets in when a lower viscosity fluid displaces a higher viscosity fluid, creates complex patterns in porous media flows. Fundamental facets of the displacement process, such as volumetric sweep and mixing efficiency, depend strongly on the type of pattern created by the uneven front of the less viscous fluid. The interface created from these fingering patterns affects mixing, and therefore is of critical importance in applications such as enhanced oil recovery and groundwater remediation. This work focuses on the evolution of a fingering interface over time, and how this evolution changes depending on the injection rate and viscosity ratio of the two miscible fluids. Initial results from both experiments and simulations show that the interface growth rate exhibits three different regimes (see figure): 1) Compact radial expansion before fingering 2) Accelerated growth of interface length due to fingering 3) Radial expansion with fixed fingers Furthermore, the experiments and simulations suggest that these are power law regimes, with viscous fingering affecting the intermediate and last regimes. The fingers affect the interface growth at intermediate times, but affect only the coefficient of scaling at late times. Since the fingers affect interface growth differently over time, understanding the mechanisms behind when and how the fingering pattern moves through these three regimes is necessary for accurately determining the interface available for mixing when viscous fingering is observed.he interface length of a fingering pattern moves through three regimes, which are characterized by the changes in the power law between total interface length and time. This fingering pattern is created from an injection of fluid ten times less viscous than the defending fluid at a rate of 0.002 mL per minute.

Chui, J.; Szulczewski, M.; Jha, B.; Juanes, R.

2012-12-01

418

Movement of Solid Particles on and off Bottom of an Unbaffled Vessel Agitated by Unsteadily Forward-Reverse Rotating Impeller  

NASA Astrophysics Data System (ADS)

An unbaffled agitated vessel having an unsteadily rotating impeller was employed as an apparatus mixing liquid and solid particles with the density larger than that of liquid. For this type of vessel, the movement of solid particles on and off the vessel bottom was studied in relation to the liquid flow produced by the impeller. When a disk turbine impeller with six flat blades was rotated in the forward-reverse mode, the liquid flow and the particle movement were visualized. Concurrently, the agitation requirement for complete solid suspension where no particle remains on the vessel bottom for more than a short period and all particles are in motion was determined as a minimum rotation rate of impeller. The liquid flow and the particle movement around a tiny heap of solid particles configured on the vessel bottom were characterized through measurement of their velocities by the particle tracking velocimetry (PTV). The relative velocity of rising with off-bottom suspension of solid particles was uniform in its distribution and wholly large in its magnitude, compared with that in a baffled vessel with a unidirectionally rotating impeller of the identical design, which revealed an effectiveness of this type of vessel as an apparatus for the solid-liquid mass transfer.

Yoshida, Masanori; Kimura, Akihiro; Yamagiwa, Kazuaki; Ohkawa, Akira; Tezura, Shuichi

419

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

420

Feasibility of a miniature centrifugal rotary blood pump for low-flow circulation in children and infants.  

PubMed

In this study, a seal-less, tiny centrifugal rotary blood pump was designed for low-flow circulatory support in children and infants. The design was targeted to yield a compact and priming volume of 5 ml with a flow rate of 0.5-4 l/min against a head pressure of 40-100 mm Hg. To meet the design requirements, the first prototype had an impeller diameter of 30 mm with six straight vanes. The impeller was supported with a needle-type hydrodynamic bearing and was driven with a six-pole radial magnetic driver. The external pump dimensions included a pump head height of 20 mm, diameter of 49 mm, and priming volume of 5 ml. The weight was 150 g, including the motor driver. In the mock circulatory loop, using fresh porcine blood, the pump yielded a flow of 0.5-4.0 l/min against a head pressure of 40-100 mm Hg at a rotational speed of 1800-4000 rpm using 1/4" inflow and outflow conduits. The maximum flow and head pressure of 5.25 l/min and 244 mm Hg, respectively, were obtained at a rotational speed of 4400 rpm. The maximum electrical-to-hydraulic efficiency occurred at a flow rate of 1.5-3.5 l/min and at a rotational speed of 2000-4400 rpm. The normalized index of hemolysis, which was evaluated using fresh porcine blood, was 0.0076