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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

Wear analysis of centrifugal slurry pump impellers  

Microsoft Academic Search

Purpose – To design and fabricate a wear testing rig for a water pump impeller and to select a parameter that can be used to determine the wear rates of slurry pump impeller. Design\\/methodology\\/approach – A wear equipment was designed and fabricated in this study that of main rotating shaft, supported by two ball bearings, and main electric motor bully

Y. A. Khalid; S. M. Sapuan

2007-01-01

3

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

4

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

2013-07-01

5

Design Method for Single-Blade Centrifugal Pump Impeller  

Microsoft Academic Search

The sewage pumps are demanded a high pump efficiency and a performance in passing foreign bodies. Therefore, the impeller used by these usages requires the large passed particle size (minimum particle size in the pump). However, because conventional design method of pump impeller results in small impeller exit width, it is difficult to be applied to the design of single-blade

Yasuyuki Nishi; Ryota Fujiwara; Junichiro Fukutomi

2009-01-01

6

Design Method for Single-Blade Centrifugal Pump Impeller  

NASA Astrophysics Data System (ADS)

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

Nishi, Yasuyuki; Fujiwara, Ryota; Fukutomi, Junichiro

7

CFD analysis of pump consortium impeller  

NASA Astrophysics Data System (ADS)

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.

1992-07-01

8

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

9

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

10

Centrifugal blood pump with a magnetically suspended impeller.  

PubMed

A centrifugal blood pump with a magnetically suspended impeller has been developed. It has a single inlet and outlet, and it generates centrifugal forces by the rotating impeller. The fluid-dynamical design for inflow and outflow through the impeller leads to elimination of the axial force and unbalanced radial force acting on the impeller. Consequently, three-component control systems, instead of five-component ones, are enough to position the impeller. The magnetically suspended impeller rotates by the magnetic coupling with the permanent magnets embedded in the outer rotator of the motor. This pump has enough performance to function as a blood pump. Further research on the null-power magnetic suspension and the generation of an efficient rotating magnetic field is in progress. PMID:10078266

Akamatsu, T; Nakazeki, T; Itoh, H

1992-06-01

11

Exit flow measurements of a centrifugal pump impeller  

Microsoft Academic Search

Discharge flows from a centrifugal pump impeller with a specific speed of 150 [rpm, m3\\/min, m] were experimentally investigated. A large axisymmetric collector instead of a volute casing was installed to obtain\\u000a circumferentially uniform flow, i.e. without interaction of the impeller and the volute. The unsteady flow was measured at\\u000a the impeller exit and vaneless diffuser using a hot film

Soon-Sam Hong; Shin-Hyoung Kang

2002-01-01

12

Flow numerical analysis within auxiliary-impellers of centrifugal pumps  

Microsoft Academic Search

For pumps with auxiliary impeller dynamic seals can meet the requirements of high efficiency, long life and high reliability, they are used more and more by industries to meet environmental protection and energy saving. However, the researches have yet been carried out little on the internal flow mechanism of the auxiliary impeller dynamic seals and their design optimization based on

Jianping Yuan; Weijie Zhang; Rong Jin; Shujuan Li; Wei Sun

2011-01-01

13

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

NASA Astrophysics Data System (ADS)

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

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

2012-01-01

14

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

Microsoft Academic Search

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

Ryunosuke Kawashima; Toshiaki Kanemoto; Kengo Sakamoto; Mitsuo Uno

2010-01-01

15

[Development and expectation of rotary impeller blood pump].  

PubMed

This essay introduces the new development of rotary impeller blood pump technology in three design aspects, i.e. pump structure, bearing and seal, control system. Moreover, an expectation for the development trend of artificial heart technology is presented. PMID:15762138

Yun, Zhong; Gong, Zhongliang; Tan, Jianping; Li, Guorong; Xu, Xiandong

2005-02-01

16

Cavitating flow investigation inside centrifugal impellers for a condensate pump  

NASA Astrophysics Data System (ADS)

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

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

2012-11-01

17

Potential flow analysis of the forces on a laboratory centrifugal pump impeller  

Microsoft Academic Search

Two dimensional potential flow was used to determine the pressure field in a laboratory centrifugal pump. The impeller and volute were modeled simultaneously, using the finite element technique. Simulation of impeller rotation was accomplished by generating steady state solutions with the impeller in 10 different angular orientations within the volute. As a result, the interaction between the impeller and volute

S. M. Miner; R. D. Flack; P. Trevisan

1992-01-01

18

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

19

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

NASA Astrophysics Data System (ADS)

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.

Xue, Dunsong; Sun, Zijing; Lu, Jun

1991-11-01

20

Failure analysis of the impeller of slurry pump used in zinc hydrometallurgy process  

Microsoft Academic Search

The failure of the trial impeller of slurry pump used in zinc hydrometallurgy process occurred only after a service of about a month, the expected service life was more than 3 months. The failure impeller was subjected to serious corrosive wear. This paper deals with failure analysis of the impeller (mainly including composition analysis of the slurry, corrosive wear surface

Ping Li; Qizhou Cai; Bokang Wei

2006-01-01

21

PARAMETRIC STUDY AND DESIGN OPTIMIZATION OF A RADIAL FLOW PUMP IMPELLER  

Microsoft Academic Search

In the present work a parametric study of a radial flow pump impeller concerning the wrap angle of the blades is presented. The design scenario contemplated here involves the maximization of impeller's efficiency by adjusting the blade's wrap angle and the number of blades. The method is used to improve the performance of an impeller of known characteristics. An optimal

Vasilios A. Grapsas; John S. Anagnostopoulos; Dimitrios E. Papantonis

22

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

23

Rate pumps for viscous crudes quickly  

SciTech Connect

The rating method is timely, because many refineries expect to process crudes much heavier than the plant was originally designed for. Not only will the existing process units require modifications, but the crude transfer pumps also become suspect due to the higher viscosity. One solution may be the addition of a light cutter stock at the pump suction to avoid a costly pump replacement. One can determine a pump's viscous operating point without having to read a derating chart or a blend index chart. The Hydraulic Institute's performance chart and the blend index chart found in Maxwell have been curve-fitted, and the resulting formulas are in the tables. These formulas are then used as part of an electronic spreadsheet that automatically determines the pump's viscous performance. The same spreadsheet also generates the piping system's head curve. A graph showing the viscous operating point can then be easily viewed and plotted using the spreadsheet's simple graphing commands.

Doane, R.C. (Litwin Engineers and Constructors, Inc., Houston, TX (United States))

1993-11-01

24

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

PubMed

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

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

2004-03-01

25

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

NASA Astrophysics Data System (ADS)

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

Yang, Zhengjun; Wang, Fujun; Zhou, Peijian

2012-09-01

26

Design optimization of a centrifugal pump impeller and volute using computational fluid dynamics  

NASA Astrophysics Data System (ADS)

In this study, optimization of the impeller and design of volute were carried out in order to improve the performance of a centrifugal pump. Design parameters from vane plane development for impeller design were selected and effect of the design parameters on the performance of the pump was analyzed using CFD and Response Surface Method to optimized impeller. This study also proposed the optimization geometry of pump impeller for performance improvement through the results from numerical analysis that was obtained optimum design pump; efficiency 98.2% and head 64.5m. In addition, the pump design method was suggested by designing volute which was suitable for the optimized impeller through volute design where Stepanoff theory was applied and numerical analysis.

Kim, J. H.; Oh, K. T.; Pyun, K. B.; Kim, C. K.; Choi, Y. S.; Yoon, J. Y.

2012-11-01

27

Improvement of washout flow in a centrifugal blood pump by a semi-open impeller.  

PubMed

To reduce the possible thrombogenicity of the pump studied, pump characteristics and washout conditions were compared between a pump with a semi-open and a pump with a full-open impeller. A difference in hydrodynamic performance was observed between the semi-open impeller and the full-open impeller; the pressure in the former was less by approximately 10%, and the maximum attainable efficiency decreased from 0.41 to 0.34. The flow pattern, as visualized by the oil film method, showed that the washout condition was enhanced by addition of the shroud, especially at the bottom region of the pump where the blood flow tended to be stagnant. The stagnant area was observed in the suction side of the impeller in both models, where the vortices shed from the impeller tip contributed to the washout. It was also shown that the flow entering the bottom region was circumferentially uniform in the full-open impeller, whereas in the semi-open impeller the flow was not uniform and entered primarily from the vicinity of the outlet port. The semi-open impeller, thus, was demonstrated to have better washout conditions than the full-open impeller regardless of a slight decrease in hydrodynamic efficiency. PMID:11814101

Tsukiya, Tomonori; Taenaka, Yoshiyuki; Tatsumi, Eisuke; Takano, Hisateru

28

Disposable MagLev centrifugal blood pump utilizing cone-shaped impeller  

Microsoft Academic Search

A magnetically levitated bio-pump (Maglev BP) has been developed. A cone-shaped impeller is suspended by a two-degree-of-freedom controlled radial magnetic bearing. Non-contact support of the impeller, using the magnetic bearing, realized higher durability compared with the bio-pump BPX-80, which is the most widely used disposable centrifugal blood pump. The MagLev BP could yield a flow rate of 5 L\\/min against

Wataru Hijikata; Tadahiko Shinshi; Akira Shimokohbe; Hideo Sobajima; Setsuo Takatani

2008-01-01

29

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

30

Unsteady pressure change in centrifugal pump impeller passages due to inlet swirl  

Microsoft Academic Search

The effects of an inlet swirl on the static pressure acting on impeller blades of a centrifugal pump were investigated experimentally. The instantaneous pressure on the blade surface was measured and the rapid change in the static pressure caused by the interaction of the vortex core and the impeller blades was clarified when a swirling flow was introduced. The pressure

K. Kikuyama; H. Hasegawa; T. Maeda

1992-01-01

31

Unsteady pressure change in centrifugal pump impeller passages due to inlet swirl  

Microsoft Academic Search

Effects of an inlet swirl on static pressure acting on impeller blades of a centrifugal pump were investigated experimentally. An instantaneous pressure on the blade surface was measured and the rapid change in the static pressure caused by the interaction of the vortex core and the impeller blades was clarified when a swirling flow was introduced. The pressure change was

Y. Hasegawa; K. Kikuyama; T. Maeda; M. Murakami

1990-01-01

32

HYDRAULIC DEVELOPMENT OF A CENTRIFUGAL PUMP IMPELLER USING THE AGILE TURBOMACHINERY DESIGN SYSTEM  

Microsoft Academic Search

The impeller of an existing industrial pump (with both geometry and performance known) was analyzed and redesigned using an integrated, design\\/analysis, turbomachinery geometry modeling and flow simulation system. The purpose of the redesign was to achieve improved impeller performance (at the duty point). Fluid dynamics and geometry modeling parts of the design\\/analysis system were systematically applied: a) to analyse the

KRZYSZTOF DENUS; COLIN OSBORNE

33

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

34

A First Analysis of Flow Field Hysteresis in a Pump Impeller  

Microsoft Academic Search

The measured pump pressure discharge characteristic for a high specific speed radial pump (?s= 1.7) reveals distinct discontinuities in part load operation. These pressure discontinuities occur at different threshold volume fluxes when increasing or decreasing the pump discharge and make up a hysteresis loop. The pump impeller characteristic was evaluated experimentally and numerically by taking the difference between the integrated

Kevin A. Kaupert; Peter Holbein; Thomas Staubli

1996-01-01

35

Flow visualization analysis of relative stagnation areas on the impeller surface of a centrifugal blood pump  

Microsoft Academic Search

To investigate deposition of platelets in centrifugal blood pumps, flow visualization analysis for a model centrifugal pump\\u000a was conducted and the results were compared with those of a numerical analysis and an animal experiment. The region behind\\u000a the impeller was investigated, and it was found that washout holes induced stagnation relative to the impeller along a belt\\u000a at 52% radius

Ahmed Aouidef; Takashi Yamane; Masahiro Nishida; Masahiro Toyoda; Yuki Tsukamoto; Kazuyuki Ito; Yoshiaki Konishi; Toru Masuzawa; Tomonori Tsukiya; Yoshiyuki Taenaka

2001-01-01

36

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

Microsoft Academic Search

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

S. C. M. Yu; B. T. H. Ng; W. K. Chan; L. P. Chua

2000-01-01

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

Dynamic characteristics of a magnetically levitated impeller in a centrifugal blood pump.  

PubMed

Centrifugal blood pumps that employ hybrid active/passive magnetic bearings to support noncontact impellers have been developed in order to reduce bearing wear, pump size, the power consumption of the active magnetic bearing, and blood trauma. However, estimates made at the design stage of the vibration of the impeller in the direction of passive suspension during pump operation were inaccurate, because the influence of both the pumping fluid and the rotation of the impeller on the dynamic characteristics was not fully recognized. The purpose of this study is to investigate the dynamic characteristics in a fluid of a magnetically levitated rotating impeller by measuring both the frequency response to sinusoidal excitation of the housing over a wide frequency range and the displacement due to input of a pulsatile flow during left ventricular (LV) assist. The excitation tests were conducted under conditions in which the impeller was levitated in either air or water, and with or without rotation. The experimental and analytical results indicate that vibration of the impeller due to the external force in water was decreased, compared with that in air due to the hydraulic force of water. The axial resonant frequency rose quadratically with rotational speed, and the tilt mode had two resonant frequencies while rotating due to the gyroscopic effect. With the pump inserted into a mock systemic circulatory loop, the dynamic stability of the impeller when pulsatile pressure was applied during LV assist was verified experimentally. The amplitudes of vibration in response to the pulsatile flow in the passively constrained directions were considerably smaller in size than the dimensions of initial gaps between the impeller and the pump housing. PMID:17437499

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

2007-04-01

39

Design of multiple impeller stirred tanks for the mixing of highly viscous fluids using CFD  

Microsoft Academic Search

The effect of multiple Intermig impeller configuration on hydrodynamics and mixing performance in a stirred tank has been investigated using computational fluid dynamics. Connection between impeller stages and compartmentalisation has been assessed using Lagrangian particle tracking. The results show that by a rotating the Intermig impeller by 45? with respect to its neighbours, instead of a 90? rotation as recommended

Joëlle Aubin; Catherine Xuereb

2006-01-01

40

Haemodynamic approach to reducing thrombosis and haemolysis in an impeller pump.  

PubMed

In the experimental and clinical support of the failing heart, the impeller-type centrifugal pumps continue to be of interest because of their inherent advantages; however, the blood compatibility of these pumps still remains to be improved. From the viewpoint of haemodynamics, thrombosis and haemolysis could be reduced by eliminating the stagnation and turbulence of blood flow within the pump, which frequently takes place near the blood contracting surfaces of the pump, when the impeller contours do not coincide with the stream surfaces of the blood. It is suggested that it could be advantageous to design impeller contours according to the stream surfaces, by solving the partial differential equations of continuity, motion and energy. An impeller shroud and vane based on this approach would be fully rinsed by non-turbulent flow and there would then be neither stagnation nor turbulence within the pump, with the result that thrombosis and haemolysis could be reduced. A new impeller pump, developed according to this method, was evaluated as a left ventricular device in four dogs. The bypass flow was controlled at 40-50% of the total flow, each test lasting 6 h. All of the haematological parameters, measured every 2 h, remained within normal range. There was no thrombosis, and coagulation in the pump was avoided by a small dose of heparin to maintain the activated coagulation time (ACT) under 200" in the experiments. PMID:2266752

Qian, K X

1990-11-01

41

Experimental study on the flow of a mixed flow pump impeller  

NASA Astrophysics Data System (ADS)

Mixed flow pump is wildly used in many field, the performance of the whole pump is affected by the flow in the impeller to a great extend. To make clear the flow phenomena in the mixed flow impeller at design and off-design flow rate condition, a mixed flow unshrouded impeller was manufactured and the flow in the impeller at design and off-design flow rate was experimental measured by Particle Image Velocimetry (PIV) in this paper. In the experiment test device, the volute was specially design and manufactured by transparent material. According to the experimental result, the distribution of time-average relatively velocity showed the velocity near blade pressure surface at design flow rate decreases and then increases from inlet to outlet of the impeller, and that near blade suction surface increase and then decreases. The velocity near the suction surface decrease from hub to casing, and the minimal velocity appears near the casing and suction surface. Near the impeller outlet, the relative velocity near blade pressure surface varies a little alone the span direction; Back-flow phenomena were found at passages outlet near casing and mid-span sections at partial flow rate. To clarify the effect of volute geometry on the velocity distribution, the flow in different impeller passages relatively to the volute tongue was test and the result showed that the velocity distribution in different passages was similar.

Lu, J. L.; Guo, P. C.; Feng, J. J.; Luo, X. Q.

2012-11-01

42

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

NASA Astrophysics Data System (ADS)

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

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

2012-11-01

43

Potential flow analysis of the forces on a laboratory centrifugal pump impeller  

NASA Astrophysics Data System (ADS)

Two dimensional potential flow was used to determine the pressure field in a laboratory centrifugal pump. The impeller and volute were modeled simultaneously, using the finite element technique. Simulation of impeller rotation was accomplished by generating steady state solutions with the impeller in 10 different angular orientations within the volute. As a result, the interaction between the impeller and volute developed naturally as a result of the solution. Model results showed that blade pressure profiles were asymmetric, even at design flow. These asymmetries were even more pronounced at off design flow rates. The causes of these asymmetries were examined in terms of the interaction between the impeller, and the tongue and discharge regions of the volute. In addition, the blade pressure profiles were integrated to determine the impeller unbalance force. The forces were calculated at design and off design flow rates. The frequency content of the forces was also examined. Fluctuating components of force, due to impeller orientation, were found to be on the order of 30 percent of the static force. Finally, a comparison was made between the computationally determined forces and measured forces reported in previous studies.

Miner, S. M.; Flack, R. D.; Trevisan, P.

1992-06-01

44

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

NASA Astrophysics Data System (ADS)

In this paper, design optimization for mixed-flow pump impellers and diffusers has been studied by using a commercial CFD code and DOE(design of experiments). We also discussed how to improve the performance of the mixed-flow pump by designing the impeller and diffuser in the mixed-flow pump. Geometric design variables were defined by the vane plane development which indicates the blade-angle distributions and length of the impeller and the diffusers. The vane plane development was controlled by using blade-angle in a fixed meridional shape. First the design optimization of the defined impeller geometric variables was done, and then the flow characteristics were analyzed in the point of incidence angle at the diffuser leading edge for the optimized impeller. Then design optimizations of the defined diffuser shape variables were performed. The importance of the geometric design variables was analyzed by using 2k factorial designs, and the design optimization of the geometric variables were determined using the response surface method. The objective functions are defined as the total head and the total efficiency at the design flow-rate. From the comparison of CFD results between optimized pump and base design model, the reason for the performance improvement was discussed.

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

2010-06-01

45

Numerical study of a bio-centrifugal blood pump with straight impeller blade profiles.  

PubMed

Computational fluid dynamic simulations of the flow in the Kyoto-NTN (Kyoto University, Kyoto, Japan) magnetically suspended centrifugal blood pump with a 16-straight-bladed impeller were performed in the present study. The flow in the pump was assumed as unsteady and turbulent, and blood was treated as a Newtonian fluid. At the impeller rotating speed of 2000 rpm and flow rate of 5 L/min, the pump produces a pressure head of 113.5 mm Hg according to the simulation. It was found that the double volute of the pump has caused symmetrical pressure distribution in the volute passages and subsequently caused symmetrical flow patterns in the blade channels. Due to the tangentially increasing pressure in the volute passages, the flow through the blade channels initially increases at the low-pressure region and then decreases due to the increased pressure. The reverse flow and vortices have been identified in the impeller blade channels. The high shear stress of the flow in the pump mainly occurred at the inlet and outlet of the blade channels, the beginning of the volute passages and the regions around the tips of the cutwater and splitter plate. Higher shear stress is obtained when the tips of the cutwater and splitter plate are located at the impeller blade trailing edges than when they are located at the middle of the impeller blade channel. It was found that the blood damage index assessed based on the blood corpuscle path tracing of the present pump was about 0.94%, which has the same order of magnitude as those of the clinical centrifugal pumps reported in the literature. PMID:19817732

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

2009-10-10

46

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

47

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

48

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

2010-05-31

49

Numerical Calculation of 2D, Unsteady Flow in Centrifugal Pumps: Impeller and Volute Interaction  

Microsoft Academic Search

A numerical model is developed for calculating the two-dimensional, unsteady, incompressible and turbulent flow within the rotating impeller and stationary volute of an industrial centrifugal pump. The objective is the investigation and comprehension of the instantaneous behaviour of centrifugal pumps, aiming at the reduction of vibrations, radial forces and hydraulic noise. The computation is performed within a blade-to-blade streamtube for

D. Croba; J. L. Kueny

1996-01-01

50

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

Microsoft Academic Search

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

John S. Anagnostopoulos

2009-01-01

51

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

NASA Astrophysics Data System (ADS)

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

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

2012-11-01

52

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

53

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

Microsoft Academic Search

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

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

2000-01-01

54

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

55

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

56

A modeling of pump impeller shroud and wear-ring seal as a whole, and its application to the pump rotordynamics  

Microsoft Academic Search

A modeling methodology of pump impeller shroud and wear-ring seal as a whole has been developed to give its rotordynamic coefficients.\\u000a In this work the governing equations are derived for the continuous flow path of the impeller shroud and wear-ring seal. Pressure\\u000a loss at the discontinuity of the connecting point between the impeller shroud and the wear-ring seal is defined

Tae Woong Ha; An Sung Lee

1998-01-01

57

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

NASA Astrophysics Data System (ADS)

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

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

2012-11-01

58

Antithrombogenicity of the Gyro permanently implantable pump with the RPM dynamic suspension system for the impeller.  

PubMed

In 1995, a group at Baylor College of Medicine started to develop the NEDO biventricular assist device (BVAD) using two Gyro permanently implantable (PI) centrifugal pumps. This pump consists of a sealless pump housing and an impeller supported with a double pivot bearing. In May 2001, an RPM dynamic suspension system (RPM-DS) for the impeller was developed to improve durability and antithrombogenicity without a complex magnetic suspension system. From March 2000 to March 2002, eight BVAD bovine experimental studies were performed for more than 1 month. Two pumps were implanted in two cases without the RPM-DS (group A) and in six cases with the RPM-DS (group B). In group A, the survival period was 45 and 50 days. The primary reason for termination was an increase in the requiring power, which was related to deposition of white thrombus on the bottom bearing. In group B, the survival period was 37, 48, 51, 60, 80, and 90 days. The reasons for termination were not related to thrombus formation. No thrombus was observed in the pumps except for one right pump. In that experiment, the thrombus formation may have occurred when that pump had a low flow rate at a level of 1 L/min for 6 hr. These studies demonstrate the apparent antithrombogenic effect of RPM-DS. The NEDO BVAD is ready to move into a 3-month preclinical system evaluation. PMID:14616527

Ichikawa, Seiji; Nonaka, Kenji; Motomura, Tadashi; Ishitoya, Hiroshi; Watanabe, Kuniyoshi; Ashizawa, Satoshi; Shinohara, Toshiyuki; Sumikura, Hirohito; Ichihashi, Fumiyuki; Oestmann, Daniel; Nosé, Yukihiko

2003-10-01

59

Large Eddy Simulation for Flow Analysis in a Centrifugal Pump Impeller  

Microsoft Academic Search

With the objective of gaining improvedinsight in the local flow behaviour and increasing the accuracy of numerical simulations\\u000a the flow field in a centrifugal pump impeller has been investigated using LES. The effect of the SGS-scales have been modelled\\u000a using a localised dynamic Smagorinsky model recently implemented in the commercial CFD code FINE\\/Turbo. Detailed flow structures\\u000a are analysed at flow

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

60

Computation of the Flow Field in a Centrifugal Impeller with Splitter Blades.  

National Technical Information Service (NTIS)

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), w...

F. J. Dejong S. Choi T. R. Govindan J. S. Sabnis

1992-01-01

61

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

NASA Astrophysics Data System (ADS)

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.

1992-07-01

62

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

63

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

64

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

NASA Astrophysics Data System (ADS)

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

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

2013-01-01

65

The Unsteady Pressure Field in a High Specific Speed Centrifugal Pump Impeller—Part I: Influence of the Volute  

Microsoft Academic Search

An experimental investigation is presented regarding the unsteady pressure field within a high specific speed centrifugal pump impeller ( vS 5 1.7) which operated in a double spiral volute. For this, twenty-five piezoresistive pressure transducers were mounted within a single blade passage and sampled in the rotating impeller frame with a telemetry system. The influence of varying volume flux on

Kevin A. Kaupert; Thomas Staubli

1999-01-01

66

Numerical and experimental comparison of the vaned diffuser interaction inside the impeller velocity field of a centrifugal pump  

Microsoft Academic Search

The paper refers to the analysis of interactions between the impeller and the vaned diffuser based on the air model of a radial\\u000a flow pump. The study deals with a numerical simulation of the flow for a full 360° entire impeller and diffuser. The task\\u000a is carried out closely under the design operating conditions and for one particular position of

Abdelmadjid Atif; Saad Benmansour; Gerard Bois; Patrick Dupont

2011-01-01

67

Large Eddy Simulation for Flow Analysis in a Centrifugal Pump Impeller  

NASA Astrophysics Data System (ADS)

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

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

68

Verifying performance of axial-flow pump impeller with low NPSHr by using CFD  

Microsoft Academic Search

Purpose – A method for optimizing net positive suction head required of axial-flow pumps has been proposed by the present author, which is based on the two-dimensional potential flow model and without considering the tip gap effect. The objective of the paper is to confirm if the method is just and feasible for the case of viscous fluid flow in

Wen-Guang Li

2011-01-01

69

Development of a surface micromachined spiral-channel viscous pump  

NASA Astrophysics Data System (ADS)

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

Kilani, Mohammad Ibrahim

70

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

71

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

72

Optimization of helico-axial multiphase pump impeller based on orthogonal experimental design  

NASA Astrophysics Data System (ADS)

In order to further optimize the helico-axial oil gas multiphase pump with higher efficiency and pressure rise, the orthogonal design method, numerical simulation and experiment investigation had been presented in this paper. Initially, for the purpose of obtaining the optimum parameters of multiphase pump with the pressure rise and efficiency as the evaluation targets, the L9(34) orthogonal table was implemented, the four parameters as factors are flange inlet angle, flange outlet angle, hub half cone angle and inlet top-hub ratio which generated nine combinations of the four parameters. Reynolds Averaged Navier-Stokes (RANS) was adopted to simulate every combination obtained by orthogonal design method, and the data of nine sets of evaluation targets were acquired which could reflect the external characteristic of the multiphase pump. Through analyzing the evaluation targets orthogonal design, the optimized combination parameters had been obtained. Then the new optimal impeller was processed and tested on the new test stand. After that, external characteristic comparison between original and optimized multiphase pump were performed in different working condition, such as the rotate speed were 3000rpm, 3600rpm, 3900rpm, 4200rpm, 4500rpm. The result showed that pressure rise and efficiency were increased respectively, also indicated the orthogonal design method combined with numerical simulation could be used for design of multiphase pump.

Zhang, Jinya; Zhu, Hongwu; Li, Yan; Yang, Chun

2009-12-01

73

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

NASA Astrophysics Data System (ADS)

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

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

2010-08-01

74

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

NASA Astrophysics Data System (ADS)

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

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

2012-11-01

75

The Unsteady Pressure Field in a High Specific Speed Centrifugal Pump Impeller—Part II: Transient Hysteresis in the Characteristic  

Microsoft Academic Search

vS 5 1.7) centrifugal pump characteristic was experimentally evaluated. A hypothesis for recirculation zones and prerotation as power dissipaters is proposed for explaining the discrepancy in the pressure and shaft power hysteresis. The experimental investigation was performed in both the rotating and stationary frame. In the rotating frame 25 miniature pressure transducers mounted in an impeller blade passage were sampled

Kevin A. Kaupert; Thomas Staubli

1999-01-01

76

Solution of diffuser inlet velocity field of radial impeller centrifugal turbine pumps by means of the LDA method  

Microsoft Academic Search

The paper deals with velocity-field analysis of a centrifugal turbine pump with radial impellers and diffuser, and especially with the diffuser-inlet velocity field. The experimental model design, the design for the LDA-method application, methodology, and measurement results on static and dynamic velocity field properties are discussed.

M. Hrabovsky

1985-01-01

77

Solution of diffuser inlet velocity field of radial impeller centrifugal turbine pumps by means of the LDA method  

NASA Astrophysics Data System (ADS)

The paper deals with velocity-field analysis of a centrifugal turbine pump with radial impellers and diffuser, and especially with the diffuser-inlet velocity field. The experimental model design, the design for the LDA-method application, methodology, and measurement results on static and dynamic velocity field properties are discussed.

Hrabovsky, M.

78

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

NASA Astrophysics Data System (ADS)

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

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

2012-04-01

79

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

80

Studies of the impact of prerotation problem of the secondary impeller on performance of multi-stage centrifugal pumps  

NASA Astrophysics Data System (ADS)

In engineering practice, part of the multi-stage centrifugal pumps is designed without space guide vanes due to the size restrictions and the volute is distorted much in shape. In these pumps, tangential velocity of the fluid at the outlet of the first-stage impeller is so great that it has caused a prerotation problem which will affect the inlet flow conditions of the secondary impeller leading to serious efficiency and head decline of the secondary impeller. The head problem of the second stage in multi-stage centrifugal pumps caused by prerotation at the entrance of the second stage was analyzed and the internal hydraulic performance was optimized by setting clapboards in the volute in this paper. CFD numerical simulation method combined with experiment was applied to predict the effect of internal clapboards on the performance of the centrifugal pump. The original prototype was transformed according to the simulation result and tested to verify the optimization work. The experiment result shows that hydraulic performance is remarkably improved compared with the original one and the prerotation problem is basically solved.

Zhai, L. L.; Wu, P.; Jiang, Q. L.; Wang, L. Q.

2012-11-01

81

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

2009-07-22

82

Fluid dynamics of a viscous drag vacuum pump  

NASA Astrophysics Data System (ADS)

An effort to miniaturize and ruggedize vacuum pumps, particularly those that function as backing and roughing pumps in mass-spectrometer gas analyzers, leads to consideration of a pump concept based upon the molecular drag principle but adapted to the continuum regime (where viscous drag principle is the appropriate term). Consider a channel bounded by a plane floor and a plane roof, the latter of which translates parallel to its own plane. Such a device will transport fluid in the direction of the roof motion even against an adverse pressure gradient---as in a compressor---provided the latter is not too large. The present work includes a formulation of a suitable analytical model, which proves to be a species of lubrication theory. In the two-dimensional problem, one obtains a first-order ordinary differential equation for the distribution of prssure along the channel, which one may solve analytically (it is of variable-separable type). The results enable estimation of pump performance when the channel is interpreted as an unwrapped form of a spiral groove cut from the surface of a drum that rotates within a smooth cylinder.

Russell, John

2002-11-01

83

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

84

Analysis of interaction between geometry and efficiency of impeller pump using rapid prototyping  

Microsoft Academic Search

Design aids available today might have helped the pump designers to bring about theoretically the most efficient pumps, but\\u000a the production technology and quality control during manufacture has not kept pace with such achievements in realizing the\\u000a goals of developing energy efficient pumps. Pump designers often face the problem of selecting and optimizing a number of\\u000a independent geometrical parameters whilst

D. Rajenthirakumar; K. A. Jagadeesh

2009-01-01

85

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

PubMed

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

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

86

Three-dimensional computations of flows in centrifugal pumps and compressors  

Microsoft Academic Search

The paper presents a three dimensional, finite difference procedure for calculating viscous flow within the impeller of a centrifugal pump or compressor. Use is made of an irregular, non-orthogonal grid system which is arranged to fit any arbitrary shaped impeller passage. The solution method is incorporated in the CATHY3 (Computer Analysis of Turbomachine Hydrodynamics in 3-dimensions) code. Attention is given

M. R. Malin; H. I. Rosten; D. G. Tatchell

1979-01-01

87

Unsteady flow in a viscous oil transporting centrifugal pump  

Microsoft Academic Search

Acoustic resonances are frequently fatal problems in centrifugal pump operations. Low pressure pulsation of fluid in the blade\\u000a pass frequency is helpful to prevent from such problems. In addition, for a high quality centrifugal pump, a lower broadband\\u000a noise level is also on demand. The acoustic resonance and broadband noise are associated with unsteadiness of flow in the\\u000a pump. Even

Wen-Guang Li

2011-01-01

88

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

PubMed Central

The use of fluids that are significantly more viscous than water in microfluidics has been limited due to their high resistance to flow in microscale channels. This paper reports a theoretical treatment for the flow of highly viscous fluids in deforming microfluidic channels, particularly with respect to transient effects, and discusses the implications of these effects on the design of appropriate microfluidic devices for highly viscous fluids. We couple theory describing flow in a deforming channel with design equations, both for steady-state flows and for the transient periods associated with the initial deformation and final relaxation of a channel. The results of this analysis allow us to describe these systems and also to assess the significance of different parameters on various deformation and/or transient effects. To exemplify their utility, we apply these design rules to two applications: (i) pumping highly viscous fluids for a nanolitre scale mixing application and (ii) precise metering of fluids in microfluidics.

Perry, Sarah L.; Higdon, Jonathan J. L.; Kenis, Paul J. A.

2013-01-01

89

Flow of viscous oil in the volute of a centrifugal pump  

NASA Astrophysics Data System (ADS)

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

Li, Wen-Guang

2002-02-01

90

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

NASA Astrophysics Data System (ADS)

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

Baskharone, Erian A.

1993-09-01

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

INVESTIGATIONS INTO PUMPING CHARACTERISTICS OF AXIAL FLOW IMPELLERS IN AN INTERNAL LOOP REACTOR FOR ANIMAL CELL CULTURE  

Microsoft Academic Search

This investigation was intended to aid in the selection of impeller design and operating conditions, which would exhibit minimum turbulence in an internal loop reactor for axial flow velocities up to 18?cm\\/s.For this purpose we measured power consumption, liquid flow velocity and mixing time with two marine propellers (pitch ratio tan alpha =1 and 0.57, respectively) and with flat-blade fan-type

ROLAND M. VARECKA; RUDOLF F. BLIEM

1990-01-01

93

Numerical and experimental study of Newtonian and non-Newtonian flow in a spiral viscous pump  

NASA Astrophysics Data System (ADS)

The need to transport small volumes of viscous media is a vital part of microfluidic devices vital to applications in biotechnology, chemistry and electronics. A novel Archimedian viscous micropump was developed in an attempt to achieve precise and accurate delivery of fluid in a robust and industrially viable package. The pump consists of a two-disc system, where one is patterned with a spiral rectangular channel of variable width and the other is smooth and has a rate of rotation ( ?) in order to pump the fluid. The width of the channel is variable along its length in order to achieve a constant local Reynolds number and avoid recirculation zones along the spiral, which is described r = a + b ?^c , where ( r ) is the radius at the spiral centerline and ( ?) is the angle. Numerical and analytical studies of the proposed model will be presented, exhibiting a linear relationship between the flow ( Q ) and ( ?). Results from experiments with a simplified prototype will also be presented supporting the analytical and numerical studies.

M{Aa}Rtensson, Gustaf; Gustafsson, Andreas

2009-11-01

94

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

SciTech Connect

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

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

2009-03-10

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

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

97

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

Microsoft Academic Search

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

Steven J

2007-01-01

98

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

National Technical Information Service (NTIS)

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 mercury pumps. The performance of nine different alloys in the as-cast...

S. J. Pawel

2007-01-01

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

Impeller Tandem Blade Study with Grid Embedding for Local Grid Refinement.  

National Technical Information Service (NTIS)

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. ...

G. Bache

1992-01-01

101

Testing of Various Options for Improving the Pumping of Viscous Oils and Emulsions  

Microsoft Academic Search

Pumping fluids recovered in a marine oil spill cleanup can be problematic, particularly in cold temperatures. The high viscosity and high pour point of weathered crude oils and emulsions can lead to difficulties in pumping operations and impose a severe bottleneck in an ongoing operation. In a series of projects over the past seven years, various aspects of dealing with

Steve Potter; Mike Bronson

102

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

103

Viscous to inertial pumping transitions in a robotic gill plate array  

NASA Astrophysics Data System (ADS)

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

Larson, Mary; Kiger, Ken

2010-11-01

104

Pulsatile impeller heart: a viable alternative to a problematic diaphragm heart.  

PubMed

The impeller blood pump with its simplicity has many advantages compared with the diaphragm pump, but the nonpulsatile property has limited its applications. To make the impeller pump pulsatile, many investigations have been made in vain because of resulting haemolysis. The author has succeeded in producing a pulsatile blood flow with a centrifugal pump, by means of the streamlined design of the impeller. The vane and shroud coincide with the blood stream surface in the pump, to eliminate the turbulence and stasis of the blood flow, which are the main factors in haemolysis and thrombosis. The pulsatility of the blood pressure and flow rate is achieved by changing the rotating speed of the impeller periodically, by introducing a square wave form voltage into the motor coil. The velocity variation of the blood cells due to the changing rotating speed of the impeller is minimized by using twisted impeller vanes, thus reducing the additional Reynolds shear, which causes the additional haemolysis in the pump. In vitro testing demonstrated that the haemolysis index of the pulsatile impeller pump is slightly higher than that of the author's nonpulsatile impeller pump but clearly less than that of other pulsatile blood pumps. The in vivo evaluations indicated that no blood damage occurred and that all haematological and biochemical data kept within a normal range during left ventricular assist experiments in calves for up to 11 days. A pulsatile impeller total heart has been developed. Two pumps are located on both sides of and driven by a d.c. motor. As the motor changes its rotating speed periodically, the left and right pumps eject the blood simultaneously, and the volume equilibrium of both pumps is achieved naturally. Acute biventricular assist experiments in pig confirmed that the device caused no blood damage. PMID:8771040

Qian, K X

1996-01-01

105

Preliminary results of impeller design modifications  

NASA Astrophysics Data System (ADS)

Power consumption in the oil mixing process is very much affected by the impeller design. Minor modification on the impeller design might result in better mixing and less energy consumption. This paper reports an early stage of applying the observation technique to modify three standard impellers, namely the Pitched blade turbine impeller, the CHEMSHEAR impeller and the Vertical Flat-Blade Turbine Impeller. The advantages and disadvantages of these three impellers were analyzed; accordingly minor modification on the impeller design is adopted. The CFD tool is used to evaluate one of the modified impellers; results indicated that the modified impeller achieves better fluid dispersion.

Yan, Y. C.; Sam, C. H.; Soo, S. E.; Khoo, X. S.; Lau, J. K.; Khek, C. H.; Younis, O.

2012-09-01

106

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

NASA Astrophysics Data System (ADS)

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

Ligrani, Phil; Blanchard, Danny; Gale, Bruce

2010-05-01

107

Pitot heat pump  

Microsoft Academic Search

A pitot heat pump is described wherein a multi-stage pitot pump is employed as the compression means in a heat pump thermodynamic cycle. The heat pump is comprised of a multi-stage vapor pitot pump, liquid pitot pump, turbine, vaporizer, evaporator, condenser and expansion valve. The turbine is used to rotate a shaft to which the impellers of the pitot pump

Grose

1981-01-01

108

Transient internal characteristic study of a centrifugal pump during startup process  

NASA Astrophysics Data System (ADS)

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

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

2012-11-01

109

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

110

Measuring axial pump thrust  

Microsoft Academic Search

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

Bernard P. Suchoza; Imre Becse

1988-01-01

111

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

112

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

NASA Astrophysics Data System (ADS)

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

1993-07-01

113

Centrifugal pumps: Design and application  

Microsoft Academic Search

The book shows how to select hydraulic geometry, predict performance, develop hydraulic passage for pump case and impeller, and analyze pump behavior. Contents include: Elements of pump design. Introduction. Specific speed and modelling laws. Impeller design. General pump design. Volute design. Design of multi-stage casing. Double-suction pumps. Diffusion casing design. Applications include. Pipelines, waterflood, and COâ pumps. High-speed, boiler feed,

V. S. Lobanoff; R. R. Ross

1985-01-01

114

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

Microsoft Academic Search

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.

Daichi Shigemaru; Hiroshi Tsukamoto

2010-01-01

115

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

116

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

117

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

118

Apparatus for pumping liquids at or below the boiling point  

DOEpatents

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

Bingham, Dennis N. (Idaho Falls, ID)

2002-01-01

119

Evaluation of the impeller shroud performance of an axial flow ventricular assist device using computational fluid dynamics.  

PubMed

Generally, there are two types of impeller design used in the axial flow blood pumps. For the first type, which can be found in most of the axial flow blood pumps, the magnet is embedded inside the impeller hub or blades. For the second type, the magnet is embedded inside the cylindrical impeller shroud, and this design has not only increased the rotating stability of the impeller but has also avoided the flow interaction between the impeller blade tip and the pump casing. Although the axial flow blood pumps with either impeller design have been studied individually, the comparisons between these two designs have not been conducted in the literature. Therefore, in this study, two axial flow blood pumps with and without impeller shrouds were numerically simulated with computational fluid dynamics and compared with each other in terms of hydraulic and hematologic performances. For the ease of comparison, these two models have the same inner components, which include a three-blade straightener, a two-blade impeller, and a three-blade diffuser. The simulation results showed that the model with impeller shroud had a lower static pressure head with a lower hydraulic efficiency than its counterpart. It was also found that the blood had a high possibility to deposit on the impeller shroud inner surface, which greatly enhanced the possibility of thrombus formation. The blood damage indices in both models were around 1%, which was much lower than the 13.1% of the axial flow blood pump of Yano et al. with the corresponding experimental hemolysis of 0.033 g/100 L. PMID:20883393

Su, Boyang; Chua, Leok P; Lim, Tau M; Zhou, Tongming

2010-09-01

120

CFD Analysis of Pump Consortium Impeller.  

National Technical Information Service (NTIS)

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 ...

G. C. Cheng Y. S. Chen R. W. Williams

1992-01-01

121

PUMP CONSTRUCTION  

DOEpatents

A pump which utilizes the fluid being pumped through it as its lubricating fluid is described. This is achieved by means of an improved bearing construction in a pump of the enclosed or canned rotor type. At the outlet end of the pump, adjacent to an impeller mechanism, there is a bypass which conveys some of the pumped fluid to a chamber at the inlet end of the pump. After this chamber becomes full, the pumped fluid passes through fixed orifices in the top of the chamber and exerts a thrust on the inlet end of the pump rotor. Lubrication of the rotor shaft is accomplished by passing the pumped fluid through a bypass at the outlet end of the rotor shaft. This bypass conveys Pumped fluid to a cooling means and then to grooves on the surface of the rotor shait, thus lubricating the shaft.

Strickland, G.; Horn, F.L.; White, H.T.

1960-09-27

122

[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

123

Flow characteristics of a centrifugal pump  

Microsoft Academic Search

Measurements of velocity have been obtained in a centrifugal pump in terms of angle-resolved values in the impeller passages, the volute, the inlet and exit ducts and are presented in absolute and relative frames. The pump comprised a radial flow impeller with four backswept blades and a single volute, and the working liquid had the same refractive index as the

C. H. Liu; C. Vafidis; J. H. Whitelaw

1994-01-01

124

HIGH-PERFORMANCE PROGRESSIVE PITCH IMPELLERS  

Microsoft Academic Search

More world and National Jet Sports Championships have been won with Skat-Trak impellers than all other impeller manufacturers combined ? State-of-the-art design and real world testing make these the impellers to beat ? High-quality investment cast 17-4 stainless steel blades feature increased strength and are thinner than stock aluminum ones for less cavitation ? All blades are CNC-machined to the

Polaris Swirl

125

Visualization of relative flow patterns in centrifugal blood pump  

Microsoft Academic Search

This paper presents computational and flow visualization results on a centrifugal blood pump. 4 impeller designs were tested\\u000a at a rotational speed of 2000 rpm using blood analog as working fluid. All impellers have seven blades but of different geometry\\u000a (Impellers A3, A4, B2 and R7). Flow visualization within the impeller passages was conducted using an image de-rotation system.\\u000a A

Weng Kong Chan; S. C. M Yu; L. P. Chua; Y. W. Wong

2001-01-01

126

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

2013-01-07

127

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

128

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

129

Blade design loads on the flow exciting force in centrifugal pump  

NASA Astrophysics Data System (ADS)

The three-dimensional viscous flow field of two centrifugal pumps, which have the same volute, design head, design flow rate and rotational speed but the blade design load, are analyzed based on large eddy simulation. The comparisons are implemented including the hydraulic efficiencies, flow field characteristics, pressure pulsations and unsteady forces applied on the impellers to investigate the effect of the design blade load on hydraulic performance and flow exciting force. The numerical results show that the efficiency of the pump, the impeller blade of which has larger design load, is improved by 1.1%~2.9% compared to the centrifugal pump with lower blade design load. The pressure fluctuation of the pump with high design load is more remarkable. Its maximum amplitude of coefficient of static pressure is higher by 43% than the latter. At the same time the amplitude of unsteady radial force is increased by 11.6% in the time domain. The results also imply that the blade design load is an important factor on the excitation force in centrifugal pumps.

Xu, Y.; Yang, A. L.; Langand, D. P.; Dai, R.

2012-11-01

130

Inverse Design Method for Centrifugal Impellers and Comparison with Numerical Simulation Tools  

Microsoft Academic Search

A process that enables us to improve the design of 2D centrifugal and helico-centrifugal pumps is presented. First of all, the definition of the impeller geometry as well as the analysis of its global performances are carried out starting from the mean streamline method (1D), based at the same time on ideal models and experimental correlations. A second stage of

Miguel Asuaje; Farid Bakir; Smaïne Kouidri; Robert Rey

2004-01-01

131

Single-disk and double-disk viscous micropumps  

Microsoft Academic Search

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

Danny Blanchard; Phil Ligrani; Bruce Gale

2005-01-01

132

Experimental study on regaining the tangential velocity energy of axial flow pump  

Microsoft Academic Search

Axial flow pumps are widely used in a wide range of applications. Although a different range of axial pump designs can be observed, axial flow pumps are usually designed for high flow rate and low pressure applications. In this study, two different axial flow pump impellers with and without guide vanes are experimentally investigated. The impellers used in the experiments

Durmus Kaya

2003-01-01

133

Viscous cavities  

NASA Astrophysics Data System (ADS)

We study experimentally the impact of solid spheres in a viscous liquid at moderate Reynolds numbers (Re ~ 5-100). We first determine the drag force by following the slowdown dynamics of projectiles. We then focus on the shape of the free surface: such impacts generate cavities, whose original shape is described and modeled.

Le Goff, Anne; Quéré, David; Clanet, Christophe

2013-04-01

134

Viscous Impact  

NASA Astrophysics Data System (ADS)

The splashing of both inviscid and viscous drops on smooth, dry surfaces can be completely suppressed by decreasing the pressure of the surrounding gas [1,2,3]. However, at sufficiently high pressure when splashing does occur, the shape and dynamics of the ejected liquid sheets depends strongly on the liquid viscosity. This, as well as the dependence of the threshold pressure on viscosity [2], suggests that the splashing of viscous and inviscid liquids is caused by different mechanisms. When a low-viscosity (˜1 cst) liquid splashes, a corona is ejected immediately upon impact. In more viscous fluids (10 cst silicone oil), our experiments show that a thin sheet, resembling a flattened version of the corona seen in the inviscid case, emerges out of a much thicker spreading film. However, for these viscous fluids, the ejection of the thin sheet does not occur immediately. As the ambient pressure is lowered, the sheet ejection time is delayed longer and longer after impact until no sheet is ejected at all. [1] L. Xu, W.W. Zhang, S.R. Nagel, Phys. Rev. Lett. 94, 184505 (2005). [2] L. Xu, Phys. Rev. E 75, 056316 (2007). [3] C. Stevens et al., FC.00003 DFD 2007

Driscoll, Michelle; Stevens, Cacey; Nagel, Sidney

2008-11-01

135

Detection of left ventricle function from a magnetically levitated impeller behavior.  

PubMed

The magnetically levitated (Mag-Lev) centrifugal rotary blood pump (CRBP) with two-degrees-of-freedom active control is promising for safe and long-term support of circulation. In this study, Mag-Lev CRBP controllability and impeller behavior were studied in the simulated heart failure circulatory model. A pneumatically driven pulsatile blood pump (Medos VAD [ventricular assist device]-54 mL) was used to simulate the left ventricle (LV). The Mag-Lev CRBP was placed between the LV apex and aortic compliance tank simulating LV assistance. The impeller behavior in five axes (x, y, z, theta, and phi) was continuously monitored using five eddy current sensors. The signals of the x- and y-axes were used for feedback active control, while the behaviors of the other three axes were passively controlled by the permanent magnets. In the static mock circuit, the impeller movement was controlled to within +/-10-+/-20 microm in the x- and y-axes, while in the pulsatile circuit, LV pulsation was modulated in the impeller movement with the amplitude being 2-22 microm. The amplitude of impeller movement measured at 1800 rpm with the simulated failing heart (peak LV pressure [LVP] = 70 mm Hg, mean aortic pressure [AoP(mean)] = 55 +/- 20 mm Hg, aortic flow = 2.7 L/min) was 12.6 microm, while it increased to 19.2 microm with the recovered heart (peak LVP = 122 mm Hg, AoP(mean) = 100 +/- 20 mm Hg, aortic flow = 3.9 L/min). The impeller repeated the reciprocating movement from the center of the pump toward the outlet port with LV pulsation. Angular rotation (theta, phi) was around +/-0.002 rad without z-axis displacement. Power requirements ranged from 0.6 to 0.9 W. Five-axis impeller behavior and Mag-Lev controller stability were demonstrated in the pulsatile mock circuit. Noncontact drive and low power requirements were shown despite the effects of LV pulsation. The impeller position signals in the x- and y-axes reflected LV function. The Mag-Lev CRBP is effective not only for noncontact low power control of the impeller, but also for diagnosis of cardiac function noninvasively. PMID:16683956

Hoshi, Hideo; Asama, Junichi; Hara, Chikara; Hijikata, Wataru; Shinshi, Tadahiko; Shimokohbe, Akira; Takatani, Setsuo

2006-05-01

136

[The study of noninvasive ventilator impeller based on ANSYS].  

PubMed

An impeller plays a significant role in the non-invasive ventilator. This paper shows a model of impeller for noninvasive ventilator established with the software Solidworks. The model was studied for feasibility based on ANSYS. Then stress and strain of the impeller were discussed under the external loads. The results of the analysis provided verification for the reliable design of impellers. PMID:21774201

Hu, Zhaoyan; Lu, Pan; Xie, Haiming; Zhou, Yaxu

2011-06-01

137

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

138

A three-dimensional potential flow analysis of dynamic fluid forces acting on a whirling centrifugal impeller bounded by a volute  

NASA Astrophysics Data System (ADS)

An unsteady three-dimensional potential flow model was developed. The panel method, as developed by Hess and Smith, formed the basis for this model. Instantaneous and time-averaged dynamic fluid forces, acting on whirling centrifugal impellers, were computed. Unbounded impellers and impellers bounded by a volute were analyzed. Inertial, damping, and stiffness matrices were presented for both types of impellers. For the unbounded impeller, the radial and tangential forces remained constant in time. Therefore, the rotor dynamic matrices possessed skew-symmetry. When bounded impellers were operated at design flows and beyond, the rotor dynamic matrices could be approximated by skew-symmetry matrices. For both the unbound and bound impeller analyses, the panel method correctly predicted radial force trends with increasing flow. However, for negative whirl speed ratios, the radial force predictions were underestimated. In the case of the unbound impeller, cross-coupling stiffness coefficients were accurately predicted at design flows and above. The destabilizing cross-coupling stiffness coefficients, which were found experimentally at flows below the design point, were not predicted by the panel method. The computational technique developed has the capability of assessing dynamic fluid forces acting on a single stage centrifugal pump. It provides analytical verification of the existence of a subsynchronous whirl instability region for centrifugal pumps bounded by a volute.

Waite, David Marc

1988-06-01

139

Seal cooling for plastic pumps  

Microsoft Academic Search

In a centrifugal pump having a thermally non-conductive plastic pump body, a rotatable impeller mounted on a rotatable drive shaft, and a mechanical seal between the pump body and the drive shaft separating a dry zone from a wet zone and comprising a rotatable seal member and a non-rotatable seal member, a cooling arrangement for the mechanical seal is described

Raab

1988-01-01

140

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

141

Electric fuel pump device  

SciTech Connect

An electric fuel pump is described having a regeneratve pump section and an electric motor section for driving the regenerative pump section. The regenerative pump section includes: a pump casing having a suction and a discharge port; a first inner surface and a second inner surface which are opposing to each other and spaced axially from each other to form therebetween a pump chamber; a substantially annular pump passage surrounding the first and second inner surfaces and connected at its ends with the suction and discharge ports, respectively; and an impeller accommodated by the pump chamber and mounted on a rotor shaft for rotation as unit therewith but axially movably relatively thereto, the impeller having one axial end surface opposing to the first inner surface of the pump casing with a first gap left therebetween and another axial end surface opposing to the second inner surface of the pump casing with a second gap left therebetween, the first inner surface and the second inner surface of the pump casing being provided with at least one axial thrust force generating surface which is so shaped as to gradually decrease the first gap and the second gap towards the downstream sides as viewed in a direction of flow of fuel introduced into the gaps, respectively, one end of the axial thrust force generating sufface terminating at the pump passage adjacent to the discharge port, so that the fuel may flow from the pump passage in a direction to the suction port along the axial thrust force generating surface thereby to minimize the chance of contact between the impeller and the first inner surface and the second inner surface of the pump casing during a running of the impeller.

Wantanabe, K.; Hattori, Y.; Matsui, K.; Takei, T.; Nakamura, T.; Ohnishi, S.

1986-05-06

142

In vivo evaluation of the NEDO biventricular assist device with an RPM dynamic impeller suspension system.  

PubMed

Since 1995, the Baylor College of Medicine group has been developing the NEDO Gyro permanent implantable (PI) pump. The Gyro PI pump has achieved outstanding results up to 284 days with no thrombus formation during the left ventricular assist device (LVAD) animal experiments. However, in biventricular assist device (BVAD) animal experiments, thrombus formation did occur. An in vitro experiment showed the reason for thrombus formation was caused by the missed magnetic balance between the impeller and the actuator. On the basis of this result, the revolutions per minute (RPM) impeller suspension system was developed. Six long-term animal studies were performed in bovine models. Survival periods were 90, 80, 60, 51, 48, and 37 days, respectively. No thrombus was observed in the pumps with the exception of one right pump. In that experiment, the thrombus formation may have occurred when the pump had a low flow because of outflow kinking. In this article, the antithrombogenic effect of this RPM impeller suspension system will be discussed. PMID:14524568

Ichikawa, Seiji; Linneweber, Joerg; Motomura, Tadashi; Ishitoya, Hiroshi; Watanabe, Kuniyoshi; Ashizawa, Satoshi; Murai, Noriyuki; Nishimura, Ikuya; Sumikura, Hirohito; Glueck, Julia A; Shinohara, Toshiyuki; Oestmann, Daniel J; Nosé, Yukihiko

143

Influence of Impeller and Diffuser Geometries on the Lateral Fluid Forces of Whirling Centrifugal Impeller.  

National Technical Information Service (NTIS)

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...

H. Ohashi A. Sakurai J. Nishihama

1989-01-01

144

PIV measurements of flow in a centrifugal blood pump: steady flow.  

PubMed

Magnetically suspended left ventricular assist devices have only one moving part, the impeller. The impeller has absolutely no contact with any of the fixed parts, thus greatly reducing the regions of stagnant or high shear stress that surround a mechanical or fluid bearing. Measurements of the mean flow patterns as well as viscous and turbulent stresses were made in a shaft-driven prototype of a magnetically suspended centrifugal blood pump at several constant flow rates (3-9 L/min) using particle image velocimetry (PIV). The chosen range of flow rates is representative of the range over which the pump may operate while implanted. Measurements on a three-dimensional measurement grid within several regions of the pump, including the inlet, blade passage, exit volute, and diffuser are reported. The measurements are used to identify regions of potential blood damage due to high shear stress and/or stagnation of the blood, both of which have been associated with blood damage within artificial heart valves and diaphragm-type pumps. Levels of turbulence intensity and Reynolds stresses that are comparable to those in artificial heart valves are reported. At the design flow rate (6 L/min), the flow is generally well behaved (no recirculation or stagnant flow) and stress levels are below levels that would be expected to contribute to hemolysis or thrombosis. The flow at both high (9 L/min) and low (3 L/min) flow rates introduces anomalies into the flow, such as recirculation, stagnation, and high stress regions. Levels of viscous and Reynolds shear stresses everywhere within the pump are below reported threshold values for damage to red cells over the entire range of flow rates investigated; however, at both high and low flow rate conditions, the flow field may promote activation of the clotting cascade due to regions of elevated shear stress adjacent to separated or stagnant flow. PMID:15971702

Day, Steven W; McDaniel, James C

2005-04-01

145

A three-dimensional passage flow analysis method aimed at centrifugal impellers  

NASA Astrophysics Data System (ADS)

A partially parabolic procedure is developed to analyze three-dimensional viscous flows through curved ducts of arbitrary cross-section. The procedure, eventually aimed at centrifugal impeller analysis, incorporates a finite-volume method using a strong conservation form of the parabolized Navier-Stokes equations written in arbitrary curvilinear coordinates. Cartesian velocity components and pressure are used as dependent variables. A solution is achieved through pressure corrections which influence velocity semi-implicitly. The basic physical elements associated with centrifugal impellers are considered. Laminar flow through 90 deg bent square duct, turbulent flow in low-aspect-ratio diffusers and subsonic compressible flow through an accelerating rectangular elbow are calculated. Turbulence is accounted for using the k - epsilon turbulence model. Good correlation between the predictions and experimental data was achieved.

Rhie, C. M.

146

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

147

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

148

Using hybrid magnetic bearings to completely suspend the impeller of a ventricular assist device.  

PubMed

Clinically available blood pumps and those under development suffer from poor mechanical reliability and poor biocompatibility related to anatomic fit, hemolysis, and thrombosis. To alleviate these problems concurrently in a long-term device is a substantial challenge. Based on testing the performance of a prototype, and on our judgment of desired characteristics, we have configured an innovative ventricular assist device, the CFVAD4, for long-term use. The design process and its outcome, the CFVAD4 system configuration, is described. To provide unprecedented reliability and biocompatibility, magnetic bearings completely suspend the rotating pump impeller. The CFVAD4 uses a combination of passive (permanent) and active (electric) magnetic bearings, a mixed flow impeller, and a slotless 3-phase brushless DC motor. These components are shaped, oriented, and integrated to provide a compact, implantable, pancake-shaped unit for placement in the left upper abdominal quadrant of adult humans. PMID:8817963

Khanwilkar, P; Olsen, D; Bearnson, G; Allaire, P; Maslen, E; Flack, R; Long, J

1996-06-01

149

Computation of incompressible viscous flows through turbopump components  

NASA Astrophysics Data System (ADS)

Flow through pump components, such as an inducer and an impeller, is efficiently simulated by solving the incompressible Navier-Stokes equations. The solution method is based on the pseudocompressibility approach and uses an implicit-upwind differencing scheme together with the Gauss-Seidel line relaxation method. the equations are solved in steadily rotating reference frames and the centrifugal force and the Coriolis force are added to the equation of motion. Current computations use a one-equation Baldwin-Barth turbulence model which is derived from a simplified form of the standard k-epsilon model equations. The resulting computer code is applied to the flow analysis inside a generic rocket engine pump inducer, a fuel pump impeller, and SSME high pressure fuel turbopump impeller. Numerical results of inducer flow are compared with experimental measurements. In the fuel pump impeller, the effect of downstream boundary conditions is investigated. Flow analyses at 80 percent, 100 percent, and 120 percent of design conditions are presented.

Kiris, Cetin; Chang, Leon

1993-02-01

150

Producibility of brazed high-dimension centrifugal compressor impellers  

Microsoft Academic Search

The centrifugal compressor impeller is a high technology machine part and its manufacture is a demanding process. The paper shows that it is possible to join high-dimensional impellers parts by brazing. Various aspects of the construction and the brazing process of high-dimensional impellers have been considered and some modifications of the brazing have been proposed. The method was applied in

J Nowacki; P ?wider

2003-01-01

151

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

152

The valvo-pump. An axial, nonpulsatile blood pump.  

PubMed

The valvo-pump, an axial, nonpulsatile blood pump implanted at the heart valve position while preserving diseased heart muscle, has several advantages over an artificial heart replacement, including 1) a good anatomic fit to the natural heart, 2) less blood contacting surface, and 3) ease of implantation. The housing for the pump is a tube, 37 mm in diameter (maximum) and 33 mm in length. Within the housing there is an impeller with either 10 vanes (33 mm in diameter) or 5 vanes (22 mm in diameter). The impeller is connected to a samarium-cobalt-rare-earth magnet direct current (DC) brushless motor measuring 23.8 mm in diameter and 30.2 mm in length. Sealing is achieved by means of a magnetic fluid seal. A guiding wheel with 4 vanes is located behind the impeller. The pump was studied on a hydraulic mock circulatory system to evaluate its performance characteristics. A pump flow of 6.9 L/min was obtained at a pump differential pressure of 48 mmHg, and flow of 3.1 L/min was obtained at 58 mmHg. The valvo-pump can be made feasible by developing a small, high-output, power motor and an endurable seal, as well as by optimizing the impeller design. PMID:1751257

Mitamura, Y; Yozu, R; Tanaka, T; Yamazaki, K

153

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

154

Method and apparatus for reducing axial thrust in centrifugal pumps  

Microsoft Academic Search

A control stator comprising a plurality of stationary vanes, ribs, or cavities is provided in a centrifugal pump having a shrouded impeller. The function of the control stator is to slow the swirl of fluid in the cavity between the casing and the impeller front shroud and thereby provide a very cost effective solution to the problem of excess axial

Alan S. Palmer; John W. Henry IV; John P. Kerr

1994-01-01

155

Performance analysis of axial-flow mixing impellers  

SciTech Connect

Theoretical formulations for impeller performance were evaluated based on a blade-element theory. These enable the calculation of the head and power vs. flow-rate curves of axial-flow impellers. The technique uses the life and drag coefficients of the blade section of an impeller to calculate the spanwise swirl-velocity distribution. Using the angular-momentum equation, it is possible to calculate the corresponding spanwise distribution of the energy head of the impeller. Integration of these distributions of head and torque gives the impeller's performance. Parameters including the flow number, the power number, the thrust force number, and the swirl velocity can be found at the impeller operating point, determined using the head curve and an experimentally calibrated resistance curve. A laser Doppler velocimetry (LDV) system was used to measure the velocity distribution for different axial flow impellers in mixing tanks. Calculated flow and power numbers agreed well with the experimental results. Using the blade's spanwise head distribution and a set of calibrated flow-resistance data, it is also possible to estimate an impeller's outlet axial-velocity distribution. Predictions compared well with LDV experimental data. The effect of impeller-blade angle, number of blades, blade camber, and blade thickness on the performance of axial-flow impellers was investigated using the Agitator software.

Wu, J.; Pullum, L.

2000-03-01

156

Radial loads and axial thrusts on centrifugal pumps  

SciTech Connect

The proceedings of a seminar organised by the Power Industries Division of the IMechE are presented in this text. Complete contents: Review of parameters influencing hydraulic forces on centrifugal impellers; The effect of fluid forces at various operation conditions on the vibrations of vertical turbine pumps; A review of the pump rotor axial equilibrium problem - some case studies; Dynamic hydraulic loading on a centrifugal pump impeller; Experimental research on axial thrust loads of double suction centrifugal pumps; A comparison of pressure distribution and radial loads on centrifugal pumps; A theoretical and experimental investigation of axial thrusts within a multi-stage centrifugal pump.

Not Available

1986-01-01

157

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

158

Sizing pumps for slurries  

SciTech Connect

Slurry characteristics have a significant impact on centrifugal pump performance. For instance, as particle size increases or the percent solids concentration increases, pump head and efficiency decrease. Therefore, before a slurry pump is selected, it is important to define the slurry characteristics as accurately as possible. The effect of the slurry characteristics on the head and efficiency of the centrifugal pump will be emphasized (the effect on flowrate is less significant). The effect of slurry characteristics is more predominant in smaller pumps (with smaller diameter impellers) than in larger pumps. The data and relationship between the various slurry parameters have been developed from correlations and nomographs published by pump vendors from their field data and test results. The information helps to avoid specifying an undersized pump/motor assembly for slurry service.

Akhtar, S.Z. [BE and K Inc., Newark, DE (United States)

1996-11-01

159

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

160

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

161

Computational flow study of the continuous flow ventricular assist device, prototype number 3 blood pump.  

PubMed

A computational fluid dynamics study of blood flow in the continuous flow ventricular assist device, Prototype 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 stagnation might occur: the impeller blade passages and the narrow gap clearance regions between the impeller-rotor and pump housing. Two separate geometry models define the spacing between the pump housing and the impeller's hub and shroud, and a third geometry model defines the pump's impeller and curved blades. The flow fields in these regions were calculated for various operating conditions of the pump. Pump performance curves were calculated, which compare well with experimentally obtained data. For all pump operating conditions, the flow rates within the gap regions were predicted to be toward the inlet of the pump, thus recirculating a portion of the impeller flow. Two smaller gap clearance regions were numerically examined to reduce the recirculation and to improve pump efficiency. The computational and geometry models will be used in future studies of a smaller pump to determine increased pump efficiency and the risk of hemolysis due to shear stress, and to insure the washing of blood through the clearance regions to prevent thrombosis. PMID:10848679

Anderson, J B; Wood, H G; Allaire, P E; Bearnson, G; Khanwilkar, P

2000-05-01

162

Centrifugal pump performance drop due to leading edge cavitation  

NASA Astrophysics Data System (ADS)

This paper deals with the leading edge cavitation of the impeller of a single stage centrifugal pump. A centrifugal pump with and without inducer is investigated by numerical simulation. The simulation results of the pump with inducer were compared with experimental data under cavitating and non-cavitating situation. An acceptable agreement has been obtained for the overall performance. Cavitation phenomena are found in varied area near the impeller inlet at the condition in the impeller flow passage and induce unexpected head drop and blade load for the pump without inducer. Violent excitement of cavitation appears at conditions of low partial flow rate and low inlet pressure. As to that with inducer, through obvious cavitation occurs in the inducer passage, no violent cavitation is found in the impeller passage. The overall performance curves are also different between the two conditions.

Li, X. J.; Pan, Z. Y.; Zhang, D. Q.; Yuan, S. Q.

2012-11-01

163

Hemocompatibility of a hydrodynamic levitation centrifugal blood pump  

Microsoft Academic Search

A noncontact type centrifugal pump without any complicated control or sensing modules has been developed as a long-term implantable\\u000a artificial heart. Centrifugal pumps with impellers levitated by original hydrodynamic bearings were designed and have been\\u000a modified through numerical analyses and in vitro tests. The hemolysis level was reduced by changing the pressure distribution around the impeller and subsequently expanding\\u000a the

Takashi Yamane; Osamu Maruyama; Masahiro Nishida; Ryo Kosaka; Daisuke Sugiyama; Yusuke Miyamoto; Hiroshi Kawamura; Takahisa Kato; Takeshi Sano; Takeshi Okubo; Yoshiyuki Sankai; Osamu Shigeta; Tatsuo Tsutsui

2007-01-01

164

Rotor-Stator-Interaction of a Radial Centrifugal Pump Stage with Minimum Stage Diameter  

Microsoft Academic Search

For radial multistage pumps with stationary vaned diffusers the diameter of the pump casing is much larger than the diameter of the impeller. In the case of submersible pumps, where just a limited space for installing the pump is available, smaller stator diameters need to be realized resulting in a loss in efficiency. Improving the design of these pumps and

D.-H. Hellmann

165

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

166

Experimental determination of dynamic characteristics of the VentrAssist implantable rotary blood pump.  

PubMed

The VentrAssist implantable rotary blood pump, intended for long-term ventricular assist, is under development and is currently being tested for its rotor-dynamic stability. The pump consists of a shaftless impeller, which also acts as the rotor of the brushless DC motor. The impeller remains passively suspended in the pump cavity by hydrodynamic forces, which result from the small clearances between the outside surfaces of the impeller and the pump cavity. These small clearances range from approximately 50 microm to 230 microm in size in the version of pump reported here. This article presents experimental investigation into the dynamic characteristics of the impeller-bearing-pump housing system of the rotary blood pump for increasing pump speeds at different flow rates. The pump was mounted on a suspension system consisting of a platform and springs, where the natural frequency and damping ratio for the suspension system were determined. Real-time measurements of the impeller's displacement were performed using Hall effect sensors. A vertical disturbance force was exerted onto the pump housing, causing the impeller to be displaced in vertical direction from its dynamic equilibrium position within the pump cavity. The impeller displacement was represented by a decaying sine wave, which indicated the impeller restoring to its equilibrium position. From the decaying sine wave the natural frequency and stiffness coefficient of the system were determined. Furthermore, the logarithmic decrement method was used to determine the damping ratio and eventually the damping coefficient of the system. Results indicate that stiffness and damping coefficients increased as flow rate and pump speed increased, representing an increase in stability with these changing conditions. However, pump speed had a greater influence on the stiffness and damping coefficients than flow rate did, which was evident through dynamic analysis. Overall the experimental method presented in this article was successful in determining the dynamic characteristics of the system. PMID:15554937

Chung, Michael K H; Zhang, Nong; Tansley, Geoff D; Qian, Yi

2004-12-01

167

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

168

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

169

First-quadrant two-phase flow in centrifugal pumps. Master's thesis  

Microsoft Academic Search

A pump system was built and instrumented on which tests were performed yielding single- and two-phase actual pump characteristics for first-quadrant operation (forward flow and forward rotation) of two different centrifugal impellers mounted in a simple two-dimensional volute. Theoretical single- and two-phase pump characteristics were determined from the impeller geometry, the Euler equation, and the use of the two-phase flow

Zegley

1977-01-01

170

PATHFINDER ATOMIC POWER PLANT PROTOTYPE RECIRCULATION PUMP REPORT  

Microsoft Academic Search

The development and testing of a centrifugal pump suitable for use in ; the recirculation system which forces core coolant and moderator through the core ; at a high rate are described. The prototype is a vertical single-stage ; centrifugal pump driven by a 400-hp induction motor. The pump has an overhung ; impeller which contains a journal for a

R. A. Haugen; D. J. Nolan

1962-01-01

171

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

172

Time–frequency characterization of the unsteady phenomena in a centrifugal pump  

Microsoft Academic Search

The paper presents an experimental investigation of the flow field instability in a centrifugal pump. Pressure fluctuations were measured with transducers placed flush with the inlet duct, and at the impeller discharge. Two impeller rotation speeds were utilized in the study, as well as several angular and radial transducer positions at design, and at off-design flow rates. A spectral analysis

G. Pavesi; G. Cavazzini; G. Ardizzon

2008-01-01

173

Over the shaft fuel pumping system  

SciTech Connect

This patent describes a high speed rotary liquid pump, adapted to be driven by a shaft in the core of a gas turbine engine. It comprises a rotatable impeller having a plurality of straight blades extending radially from an annular hub, the hub having a central aperture of sufficient size to engage the shaft for rotation therewith; a pump housing surrounding the impeller and defining a generally annular pump cavity for receiving the rotatable impeller; the housing also defining an annular fluid inlet aperture leading axially into the cavity adjacent the hub, a shield member axially adjacent the aperture and disposed between fluid entering the aperture and the shaft, whereby circumferential swirl of the fluid due to contact with the shaft is minimized, and at least one fluid outlet passage extending tangentially from the periphery of the cavity adjacent the tips of the blades.

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

1991-06-11

174

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

175

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

176

Characterization of axial flow impellers in pulp fibre suspensions  

Microsoft Academic Search

Two axial flow impellers commonly used in pulp agitation applications were characterized in hardwood and softwood low-consistency pulp fibre suspensions. The impellers operated in the laminar and transition-to-turbulence regimes with the suspension mass concentration significantly affecting both power and axial thrust numbers. Axial force numbers could be collapsed to a single operating curve using the yield stress Reynolds number, but

M. Bhole; C. Ford; C. P. J. Bennington

2009-01-01

177

Numerical simulation of impeller-volute interaction in centrifugal compressors  

Microsoft Academic Search

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

K. Hillewaert; R. A. Van den Braembussche

1999-01-01

178

The valvo-pump, an axial blood pump implanted at the heart valve position: concept and initial results.  

PubMed

The valvo-pump, an axial nonpulsatile blood pump implanted at the heart valve position, has been developed. The valvo-pump consists of an impeller and a motor, which are encased in a housing. An impeller with 5 vanes (22.0 mm in diameter) is used. The impeller is connected to a samarium-cobalt-rare earth magnet direct current (DC) brushless motor measuring 21.3 mm in diameter and 18.5 mm in length. Sealing is achieved by means of a ferrofluidic seal. A pump flow of 10.5 L/min was obtained at a pump differential pressure of 3.3 kPa (25 mm Hg), and a flow of 4.9 L/min was obtained at 7.0 kPa (53 mm Hg). Sealing was kept perfect against a pressure of 29.3 kPa (220 mm Hg) at 9,000 rpm. PMID:10078263

Yamazaki, K; Okamoto, E; Yamamoto, K; Mitamura, Y; Tanaka, T; Yozu, R

1992-06-01

179

Incompressible Navier-Stokes calculations in pump flows  

NASA Astrophysics Data System (ADS)

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

Kiris, Cetin; Chang, Leon; Kwak, Dochan

1993-07-01

180

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

181

The cavitation behavior with short length blades in centrifugal pump  

Microsoft Academic Search

A CFD code with 2-D cascade model was developed to predict the cavitation behavior around the impeller blades of impeller\\u000a in a centrifugal pump. The governing equations are the two-phase Reynolds Averaged Navier-Stokes equations in a homogeneous\\u000a form in which both liquid and vapor phases are treated as incompressible fluid. To close the model, a standard k-? turbulence\\u000a model is

Quangnha Thai; Changjin Lee

2010-01-01

182

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

183

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

184

Submersible canned motor transfer pump  

DOEpatents

A transfer pump is described which is used in a waste tank for transferring high-level radioactive liquid waste from a waste tank and having a column assembly, a canned electric motor means, and an impeller assembly with an upper impeller and a lower impeller connected to a shaft of a rotor assembly. The column assembly locates a motor housing with the electric motor means adjacent to the impeller assembly which creates an hydraulic head, and which forces the liquid waste, into the motor housing to cool the electric motor means and to cool and/or lubricate the radial and thrust bearing assemblies. Hard-on-hard bearing surfaces of the bearing assemblies and a ring assembly between the upper impeller and electric motor means grind large particles in the liquid waste flow. Slots in the static bearing member of the radial bearing assemblies further grind down the solid waste particles so that only particles smaller than the clearances in the system can pass there through, thereby resisting damage to and the interruption of the operation of the transfer pump. The column assembly is modular so that sections can be easily assembled, disassembled and/or removed. A second embodiment employs a stator jacket which provides an alternate means for cooling the electric motor means and lubricating and/or cooling the bearing assemblies, and a third embodiment employs a variable level suction device which allows liquid waste to be drawn into the transfer pump from varying and discrete levels in the waste tank. 17 figs.

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

1997-08-19

185

Viscous extensional film withdrawal  

NASA Astrophysics Data System (ADS)

When a viscous film is withdrawn from a bath of fluid the dominant flow in the film is extensional, unlike the shear flow which occurs in e.g. thin films wetting solid objects that are withdrawn from a bath of fluid. Previous work revisited theory describing the thickness of a soap film withdrawn from a bath, and found that it scales as h Cs^2/3, where Cs is the surface capillary number which accounts for surface viscosity. For viscous films without surfactants, and hence no surface viscosity, film thickness was found to scale as h Ca^2 for Ca << 1. In this work, we compare the theoretical predictions to experimental and numerical investigations of viscous film thicknesses, and furthermore we consider regimes where other contributions to the stress balance are important, such as gravity for Ca=O(1).

van Nierop, Ernst A.; Scheid, Benoit; Heller, Martin; Bruus, Henrik; Stone, Howard A.

2008-11-01

186

Numerical Study and Optimal Blade Design of a Centrifugal Pump by Evolutionary Algorithms  

Microsoft Academic Search

A numerical methodology for hydrodynamic design in centrifugal pumps is developed and tested, considering the possibility\\u000a to increase the hydraulic efficiency of the pump impeller by improving the blades shape. The simulation and analysis of the\\u000a incompressible turbulent flow through the test impeller is performed with a commercial CFD code, and the numerical results\\u000a are in agreement with the corresponding

Vasilis Grapsas; Fotis Stamatelos; John Anagnostopoulos; Dimitris Papantonis

2008-01-01

187

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

188

Magnetically suspended centrifugal blood pump with a self bearing motor.  

PubMed

A magnetically suspended centrifugal blood pump with a self bearing motor has been developed for long-term ventricular assistance. A rotor of the self bearing motor is actively suspended and rotated by an electromagnetic field without mechanical bearings. Radial position of the rotor is controlled actively, and axial position of the rotor is passively stable within the thin rotor structure. An open impeller and a semiopened impeller were examined to determine the best impeller structure. The outer diameter and height of the impeller are 63 and 34 mm, respectively. Both the impellers indicated similar pump performance. Single volute and double volute structures were also tested to confirm the performance of the double volute. Power consumption for levitation and radial displacement of the impeller with a rotational speed of 1,500 rpm were 0.7 W and 0.04 mm in the double volute, while those in the single volute were 1.3 W and 0.07 mm, respectively. The stator of the self bearing motor was redesigned to avoid magnetic saturation and improve motor performance. Maximum flow rate and pressure head were 9 L/min and 250 mm Hg, respectively. The developed magnetically suspended centrifugal blood pump is a candidate for an implantable left ventricular assist device. PMID:12141477

Masuzawa, Toru; Onuma, Hiroyuki; Kim, Seung-Jong; Okada, Yohji

189

A novel integrated electric motor\\/pump for underwater applications  

Microsoft Academic Search

This article presents a novel electric motor\\/pump system that combines an axial field, permanent magnet motor with a centrifugal pump. This system, unique because the motor permanent magnet rotor and pump impeller vanes are a single unit, provides a compact, reliable, low-noise, and high-power density electrically driven centrifugal pump suitable for underwater applications in which minimizing noise, vibration, and volume

C. Peter Cho; Barry K. Fussell; John Y. Hung

1996-01-01

190

Computational fluid dynamic design of rocket engine pump components  

Microsoft Academic Search

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

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

1992-01-01

191

Use minimum flow data to prolong centrifugal pump life  

Microsoft Academic Search

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

1996-01-01

192

Viscous extensional film withdrawal  

Microsoft Academic Search

When a viscous film is withdrawn from a bath of fluid the dominant flow in the film is extensional, unlike the shear flow which occurs in e.g. thin films wetting solid objects that are withdrawn from a bath of fluid. Previous work revisited theory describing the thickness of a soap film withdrawn from a bath, and found that it scales

Ernst A. van Nierop; Benoit Scheid; Martin Heller; Henrik Bruus; Howard A. Stone

2008-01-01

193

Bulk viscous cosmology  

Microsoft Academic Search

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

R. Colistete J; J. C. Fabris; J. Tossa; W. Zimdahl

2007-01-01

194

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

2012-07-23

195

The margin of safety in the use of a straight path centrifugal blood pump.  

PubMed

A new centrifugal blood pump with a rotor that arranges 6 straight paths radially was developed for open heart surgery and temporary circulatory support. We describe comparative studies of the margin of safety in the practical use of the new pump. This pump was evaluated for temperature increase, cavitation, and pressure sensitivity. Two commercially available centrifugal pumps, the Biomedicus cone type and the Sarns 3M impeller type, were used as control pumps. The temperature increase in the new pump was four times slower than in the impeller pump when the outlet and the inlet of the pump was clamped. No sign of cavitation was observed when 0.1 ml air was introduced to the pump inlet under a negative pressure of 200 mm Hg in fresh bovine blood. As for pressure sensitivity of centrifugal pumps in practical applications, circuit resistance was a more essential factor than flow-pressure curves of the pump. PMID:7998886

Kijima, T; Nojiri, C; Oshiyama, H; Horiuchi, K; Nogawa, A; Hamasaki, H; Ogihara, M; Katsuda, H S; Amano, N; Fukasawa, H

1994-09-01

196

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

197

Numerical simulation of impeller-volute interaction in centrifugal compressors  

SciTech Connect

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

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

1999-07-01

198

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

NASA Astrophysics Data System (ADS)

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

Mishina, H.; Nishida, H.

1983-03-01

199

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

200

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.

201

Impeller geometry effect on crystallization kinetics of borax decahydrate in a batch cooling crystallizer  

Microsoft Academic Search

The effects of impeller type and diameter in a batch cooling crystallizer on the nucleation and crystal growth kinetics as well as on the shape and size distribution of borax decahydrate crystals were investigated. Two different types of impellers of various sizes were applied. Chosen impeller configurations generate completely different fluid flow patterns in the crystallizer what allows to investigate

Marija Akrap; Nenad Kuzmani?; Jasna Prli? Kardum

202

Lateral fluid forces on whirling centrifugal impeller. I - Theory. II - Experiment in vaneless diffuser  

Microsoft Academic Search

Lateral fluid forces acting on a rotating centrifugal impeller in whirling motion are analyzed using unsteady potential flow theory. Impellers operating in diffusers with and without vanes are modeled and the fluid forces calculated for different whirl speeds and flow rates. The influences of these parameters are clarified by parametric calculations. The results for whirling impellers operating in vaneless diffusers

H. Shoji; H. Ohashi

1987-01-01

203

Preventing cavitation in high energy centrifugal pumps  

SciTech Connect

Large-eye impellers for high energy centrifugal pumps were developed to meet the specification of reduced NPSH{sub r} at rated flow conditions. Unfortunately, this improved NPSH performance was not without adverse tradeoffs because an abnormal increase in noise, vibration and cavitation erosion were experienced at low flows. Centrifugal pumps are often used under widely varying and adverse conditions, and in the case of high energy and large-eye impeller pumps, these conditions should be evaluated very carefully. At petrochemical complexes in Secunda in the Republic of South Africa, a centrifugal pump application for lean carbonate solution experienced frequent failures. An investigation and literature survey indicated the cause was low flow cavitation. The purpose of this article is but to give design guidelines as obtained from literature and experience.

Garbers, A.W.F.; Wasfi, A.K. (Sastech Engineering Services (Pty) Ltd. (ZA))

1990-07-01

204

Computational fluid dynamic design of rocket engine pump components  

NASA Astrophysics Data System (ADS)

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.

1992-07-01

205

A seal-less centrifugal pump (Baylor Gyro Pump) for application to long-term circulatory support.  

PubMed

We are developing a new centrifugal pump, the Baylor Gyro Centrifugal Pump (Gyro Pump), which can function for more than 2 weeks. The concept of the Gyro Pump is that a one-piece rotor-impeller with embedded permanent magnets, driven directly by a brushless direct current motor stator placed outside, rotates like a "gyroscope," and the rotor-impeller is supported by one pivot bearing at the bottom in accordance with the gyroscopic principle. This concept enables us to eliminate a driving shaft and a seal between the driving shaft and the blood chamber, which results in extending the life of the centrifugal pump. The blood passes through the space between the motor stator and the rotor to the impeller portion. In this preliminary phase, two pivot bearings were applied to support the rotor-impeller at the top and the bottom inside the blood chamber. Both pivot bearings showed less blood trauma and less thrombogenicity in in vitro and in vivo studies. The Gyro Pump is a promising second-generation centrifugal pump for long-term circulatory support in the near future. PMID:8422233

Minato, N; Sakuma, I; Sasaki, T; Shiono, M; Ohara, Y; Takatani, S; Noon, G P; Nosé, Y

1993-01-01

206

Rotating Instability of a Centrifugal Compressor with 2Dimensional Impeller  

Microsoft Academic Search

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

Kyung Jun Kang; You Hwan Shin; Kwang Ho Kim

2010-01-01

207

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

208

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

209

Effect of impeller geometry and tongue shape on the flow field of cross flow fans  

NASA Astrophysics Data System (ADS)

Experiments were conducted to investigate the effect of impeller geometry and tongue shape on the flow field of cross flow fans. Three impellers (I, II, III) having same outer diameter, but different radius ratio and blade angles were employed for the investigation. Each impeller was tested with two tongue shapes. Flow survey was carried out for each impeller and tongue shape at two flow coefficients, and for each flow coefficient at different circumferential positions. The flow is two-dimensional along the blade span except near the shrouds. The total pressure developed by the impellers in each case is found to be maximum at a circumferential position of around 270°. The total and static pressures at the inlet of impellers are more or less same regardless of impeller and tongue geometry, but they vary considerably at exit of the impellers. Impeller III with tongue T 2 develops higher total pressure and efficiency where as impeller II with tongue T 2 develops minimum total pressure. Higher diffusion and smaller vortex size are the reasons for better performance of impeller III with tongue T 2.

Govardhan, M.; Venkateswarlu, G.

2003-05-01

210

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

NASA Astrophysics Data System (ADS)

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

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

2012-11-01

211

Crystal size distribution of aluminum potassium sulfate in a batch crystallizer equipped with different types of impeller  

Microsoft Academic Search

In order to investigate the effect of impeller type on the crystal size distributions, three different types of impellers, which produce different flow patterns were used in the crystallization of aluminum potassium sulfate in a seeded batch crystallizer. Two maxima in size distributions were obtained when impellers producing radial flow are used at higher impeller speeds, whereas only a single

Kenji Shimizu; Toshio Nomura; Koji Takahashi

1998-01-01

212

Diagnosis of Centrifugal Pump Faults Using Vibration Methods  

NASA Astrophysics Data System (ADS)

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

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

2012-05-01

213

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

PubMed

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

Hu, Jinfei; Tse, Peter W

2013-09-18

214

Bursting of Viscous Films  

NASA Astrophysics Data System (ADS)

The disintegration of a thin film of an inviscid fluid due to a growing hole was studied by Taylor and Culick. A cylindrical rim appears at the end of the film, which retracts at a constant velocity V_0. Debrégeas, de Gennes and Brochard-Wyart have conducted experiments with highly viscous viscoelastic films showing that the retraction velocity is exponential at short times and saturates to a constant value at late times. They observe also that the films have uniform thickness and no end rim, and explain this using an argument of viscoelasticity. We show that the uniform thickness might be a purely viscous response of the system. A rim exists at the end of the film but its axial length is controlled by the Oseen length ? / V_0. If this length is larger than the axial extent of the film, as in the experiments, then the film is uniformly flat. If not, a rim exists and its shape is described by a self-similar evolution. A similarity solution is presented.

Gueyffier, Denis; Brenner, Michael

1998-11-01

215

Viscous microdetonation physics  

NASA Astrophysics Data System (ADS)

Viscous and diffusion effects on the propagation of detonations in micron-sized channels are investigated by means of numerical calculations of the Navier Stokes equations. It is shown that an initial ZND (Zeldovich, Neumann, Döring) supersonic combustion wave becomes unstable. Distinct galloping detonation waves characterized by deviations from the inviscid dynamics propagate at different distances from the walls of the channel. The deviations include enhanced maxima in the front's pressure and multiple ignition. For the larger Reynolds numbers studied (Re=2400), the geometry and speed of the front are affected by the propagation of transverse waves. The latter are responsible for the formation of periodic in time patterns in the graphs of maximal pressure. For smaller Reynolds numbers (Re=240), the patterns are damped by viscous processes. Although occasionally the front weakens significantly during its periodic dynamics, the detonation is not quenched; its speed is non-uniform, sometimes been higher close to the wall, other times been higher close to the centerline.

Kivotides, Demosthenes

2007-04-01

216

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

2005-09-23

217

Resilient shaft mounting for pump  

SciTech Connect

This patent describes a pump. It comprises: a tube having a centrifugal pump mounted on an upper end thereof, the centrifugal pump having an inlet coaxial with the tube, an outlet disposed radially and an impeller rotatable in a housing to pump a liquid; at least one propeller disposed in the tube below the centrifugal pump, the propeller being rotatable to draw fluid upwardly in the tube; a shaft connecting the impeller of the centrifugal with the propeller in the tube; at least one triangular support for the shaft, having three resilient planar plates dimensioned to be bowed inwardly in the tube and enclosing the shaft. The plates are discrete sections, each having ends disposed against an inner surface of the tube and against an adjoining one of the plates, an intermediate portion of each of the plates resiliently bearing inwardly toward the shaft; and, a resilient bushing disposed between the plates and the shaft, the resilient bushing being a round tube deformed into a triangular shape by pressure of the plates; whereby the shaft is supported coaxially in the tube.

Valentine, W.

1990-06-12

218

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

219

Laboratory-scale finned-rotor impeller for dialysis.  

PubMed

Dialysis of blood and other fluids may be accomplished using semi-permeable membranes. Most commonly used are the commercially available hollow-fibre dialysers, which have large priming volumes, an important consideration especially when laboratory techniques are being developed. With dialysis tubing (DT), however, priming volumes are readily controlled. To ensure adequate mass transfer, mixing of both dialysate and DT content is necessary. An impeller-based dialyser which consists of two open-boxed finned rotors facilitates both dialysate and DT content mixing. The operation of this device relies on the difference in hydrodynamic forces acting on opposite ends of the rotors, causing rotation in the vertical plane. This laboratory device was assessed via mass-transfer trials in which saline and washed-packed erythrocytes were dialysed against hypo- and hypertonic dialysate, allowing estimation of the DT's overall mass-transfer coefficient. Experimental correlation between the angular speeds of the impeller's rotation in the horizontal plane omega H and finned rotors' rotation in the vertical plane omega V were also established. Results indicate that the osmolality of the DT's content follows an exponential decay, and that omega V is strongly dependent on both omega H and the submergence depth of the impeller. PMID:2622234

el-Kalay, M A; Nasser, A E

1989-09-01

220

Magnetically suspended centrifugal blood pump with a radial magnetic driver.  

PubMed

A new magnetic bearing has been designed to achieve a low electronic power requirement and high stiffness. The magnetic bearing consists of 1) radial passive forces between the permanent magnet ring mounted inside the impeller rotor and the electromagnet core materials in the pump casing and 2) radial active forces generated by the electromagnets using the two gap sensor signals. The magnetic bearing was assembled into a centrifugal rotary blood pump (CRBP) driven with a radial, magnetic coupled driver. The impeller vane shape was designed based upon the computational fluid dynamic simulation. The diameter and height of the CRBP were 75 mm and 50 mm, respectively. The magnetic bearing system required the power of 1.0-1.4 W. The radial impeller movement was controlled to within +/- 10 microm. High stiffness in the noncontrolled axes, Z, phi, and theta, was obtained by the passive magnetic forces. The pump flow of 5 L/min against 100 mm Hg head pressure was obtained at 1,800 rpm with the electrical to hydraulic efficiency being greater than 15%. The Normalized Index of Hemolysis (NIH) of the magnetic bearing CRBP was one fifth of the BioPump BP-80 and one half of the NIKKISO HPM-15 after 4 hours. The newly designed magnetic bearing with two degrees of freedom control in combination with optimized impeller vane was successful in achieving an excellent hemolytic performance in comparison with the clinical centrifugal blood pumps. PMID:15745136

Hoshi, Hideo; Katakoa, Kiroyuki; Ohuchi, Katsuhiro; Asama, Jun-ichi; Shinshi, Tadahiko; Shimokohbe, Akira; Takatani, Setsuo

221

Inverse Design Method for Centrifugal Impellers and Comparison with Numerical Simulation Tools  

NASA Astrophysics Data System (ADS)

A process that enables us to improve the design of 2D centrifugal and helico-centrifugal pumps is presented. First of all, the definition of the impeller geometry as well as the analysis of its global performances are carried out starting from the mean streamline method (1D), based at the same time on ideal models and experimental correlations. A second stage of optimisation is achieved from a quasi three-dimensional (Q3D) method, by studying the meridional flow and blade-to-blade flow. Finally, 3D flow solution is performed by CFD tools. Nowadays, we have a group of tools which help the designers improve the performance of new machines. These digital tools are built around two computer programs, HELIOX developed for design and performance analysis in any centrifugal and mixed flow pumps equipped with volute or deswirl vanes, and also the module REMIX that gathers the meridional flow analysis and the simplified blade-to-blade one. To validate this procedure, a centrifugal machine with a volute (NS32) was modified and studied with it, and the results were simultaneously compared with the previous trial runs and with the software CFX-BladeGEN+ and CFX-TASCflow. The results for a machine equipped with a deswirl (VM51) are also presented.

Asuaje, Miguel; Bakir, Farid; Kouidri‡, Smaïne; Rey¶, Robert

2004-02-01

222

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

223

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

224

Viscous exchange flows  

NASA Astrophysics Data System (ADS)

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

Matson, Gary P.; Hogg, Andrew J.

2012-02-01

225

Development of the hydrotransport boost pump. Open file report September 1981-December 1984  

SciTech Connect

A ventilated helical boost pump was developed that can handle varying flow rates and/or solids concentrations while operating at a single rotational speed and without computer assisted feedback controls. The boost pump developed and briefly tested during this program was designed to accomodate flows suitable for a 3-in-diam pipeline. The boost pump's ventilated design provides the automatic pressure regulation needed to meet the system's requirements for supporting transient pipeline flow. A maximum discharge pressure of 120 psi was achieved at an operating speed of 3,000 rpm. The boost pump efficiency at maximum discharge pressure was 65 pct. Coal flow rates of up to 1,000 lb/min were successfully processed with a nonshrouded single vane impeller. Further redesign is required to develop a shrouded impeller that can be combined with stationary wear rings to minimize impeller wear.

Rubin, L.S.; Cardenas, R.L.; Burnette, M.; Roberge, J.; Harvey, A.

1984-12-31

226

Canned pump having a high inertia flywheel  

DOEpatents

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

Veronesi, L.; Raimondi, A.A.

1989-12-12

227

[Research on the feasibility of a magnetic-coupling-driven axial flow blood pump].  

PubMed

A new-designed axial flow blood pump, dived by magnetic coupling and using internal hollow brushless DC motor and inlet and outlet in line with impeller, was tested in mimic circuit. The results showed good performance of the new pump and indicated that its hydrodynamic characteristic can meet the demands of clinical extracorporeal circulation and auxiliary circulation. PMID:15022483

Yu, Xiaoqing; Ding, Wenxiang; Wang, Wei; Chen, En; Jiang, Zuming; Zou, Wenyan

2004-02-01

228

The effect of inlet swirl on the rotordynamic shroud forces in a centrifugal pump  

Microsoft Academic Search

The role played by fluid forces in determining the rotordynamic stability of a centrifugal pump is gaining increasing attention. The present research investigates the contributions to the rotordynamic forces from the discharge-to-suction leakage flows between the front shroud of the rotating impeller and the stationary pump casing. In particular, the dependency of the rotordynamic characteristics of leakage flows on the

A. Guinzburg; C. E. Brennen; A. J. Acosta; T. K. Caughey

1993-01-01

229

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

230

Computational fluid dynamics analysis of the pediatric tiny centrifugal blood pump (TinyPump).  

PubMed

We have developed a tiny rotary centrifugal blood pump for the purpose of supporting circulation of children and infants. The pump is designed to provide a flow of 0.1-4.0 L/min against a head pressure of 50-120 mm Hg. The diameter of the impeller is 30 mm with six straight vanes. The impeller is supported by a hydrodynamic bearing at its center and rotated with a radial coupled magnetic driver. The bearing that supports rotation of the impeller of the tiny centrifugal blood pump is very critical to achieve durability, and clot-free and antihemolytic performance. In this study, computational fluid dynamics (CFD) analysis was performed to quantify the secondary flow through the hydrodynamic bearing at the center of the impeller and investigated the effects of bearing clearance on shear stress to optimize hemolytic performance of the pump. Two types of bearing clearance (0.1 and 0.2 mm) were studied. The wall shear stress of the 0.1-mm bearing clearance was lower than that of 0.2-mm bearing clearance at 2 L/min and 3000 rpm. This was because the axial component of the shear rate significantly decreased due to the narrower clearance even though the circumferential component of the shear rate increased. Hemolysis tests showed that the normalized index of hemolysis was reduced to 0.0076 g/100 L when the bearing clearance was reduced to 0.1 mm. It was found that the CFD prediction supported the experimental trend. The CFD is a useful tool for optimization of the hydrodynamic bearing design of the centrifugal rotary blood pump to optimize the performance of the pump in terms of mechanical effect on blood cell elements, durability of the bearing, and antithrombogenic performance. PMID:16683958

Kido, Kazuyuki; Hoshi, Hideo; Watanabe, Nobuo; Kataoka, Hiroyuki; Ohuchi, Katsuhiro; Asama, Junichi; Shinshi, Tadahiko; Yoshikawa, Masaharu; Takatani, Setsuo

2006-05-01

231

Coiling of viscous jets  

NASA Astrophysics Data System (ADS)

A stream of honey poured from a sufficient height forms a series of helical coils as it approaches a piece of toast. I have studied the dynamics of this instability using an asymptotic theory for a thin inertia-free viscous jet that deforms under the action of gravity and surface tension. The jet's shape is described by the radius of its cross-section and the curvature and torsion of its axis, as functions of arclength and time. Such a jet can experience four distinct modes of deformation: stretching/shortening; bending in the local osculating plane; bending out of the osculating plane; and twisting. The instantaneous response of the jet to applied loads is described by a twelfth-order system of coupled ordinary differential equations, comprising the equations of global (integrated) force and moment balance together with appropriate constitutive relations for the stress resultants and bending moments. The temporal evolution of the jet's radius and axial shape is described by additional kinematic equations of hyperbolic type. The equations are solved numerically using a relaxation method for the instantaneous response and a staggered leapfrog scheme for the time evolution. The critical feature of the dynamics is a bifurcation from a state of ``forced'' coiling in which buoyancy forces are negligible to one of ``free'' coiling in which those forces are dominant. I will present scaling laws for the coiling frequency in both regimes, as functions of the pouring height, the flow rate, the initial jet radius, and the fluid properties.

Ribe, Neil

2002-11-01

232

Viscous dark fluid universe  

SciTech Connect

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

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

2010-09-15

233

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

234

TRANSIENT BEHAVIOR OF THE VISCOUS MICROPUMP  

Microsoft Academic Search

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

M. Abdelgawad; I. Hassan; N. Esmail

2004-01-01

235

Inlet and outlet devices for rotary blood pumps.  

PubMed

The purposes of inlet and outlet devices for rotary blood pumps, including inducers and diffusers for axial pumps, inlet and exit volutes for centrifugal pumps, and inlet and outlet cannulas, are to guide the blood into the impeller, where the blood is accelerated, and to convert the high kinetic energy into pressure after the impeller discharge, respectively. The designs of the inlet and outlet devices have an important bearing on the pump performance. Their designs are highly dependent on computational fluid dynamics (CFD) analysis, guided by intuition and experience. For inlet devices, the design objectives are to eliminate separated flow, to minimize recirculation, and to equalize the radial components of velocity. For outlet devices, the design goals are to reduce speed, to minimize energy loss, and to avoid flow separation and whirl. CFD analyses indicate the velocity field and pressure distribution. Geometrical optimization of these components has been implemented in order to improve the flow pattern. PMID:15384997

Song, Xinwei; Wood, Houston G; Allaire, Paul E; Antaki, James F; Olsen, Don B

2004-10-01

236

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

PubMed

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

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

2009-04-01

237

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

238

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

239

Cast Titanium Alloy Radial Impellers: A new casting process costs less than conventional forging and machining.  

National Technical Information Service (NTIS)

This citation summarizes a one-page announcement of technology available for utilization. A casting process for the fabrication of Ti-6A1-4V alloy radial-compressor impellers has been developed. Impellers made by the improved process cost less than simila...

1982-01-01

240

Mathematical modeling and computer simulation of molten aluminum cleansing by the rotating impeller degasser  

Microsoft Academic Search

Rotary degassing is widely used in the foundry industry for removing hydrogen gas and solid impurities from molten aluminum alloys. In this method, a specially designed impeller rotates inside the melt and gas is purged into the molten alloy through holes located at the bottom of the impeller. The purged gas forms bubbles that rise to the melt's surface. While

V. S. Warke; S. Shankar; M. M. Makhlouf

2005-01-01

241

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

Microsoft Academic Search

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

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

1995-01-01

242

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

Microsoft Academic Search

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

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

1997-01-01

243

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

Microsoft Academic Search

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

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

1996-01-01

244

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

Microsoft Academic Search

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

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

1995-01-01

245

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

246

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

PubMed

To overcome the drive shaft seal and bearing problem in rotary blood pumps, a hydrodynamic bearing, a magnetic fluid seal, and a brushless direct current (DC) motor were employed in an axial flow pump. This enabled contact-free rotation of the impeller without material wear. The axial flow pump consisted of a brushless DC motor, an impeller, and a guide vane. The motor rotor was directly connected to the impeller by a motor shaft. A hydrodynamic bearing was installed on the motor shaft. The motor and the hydrodynamic bearing were housed in a cylindrical casing and were waterproofed by a magnetic fluid seal, a mechanically noncontact seal. Impeller shaft displacement was measured using a laser sensor. Axial and radial displacements of the shaft were only a few micrometers for motor speed up to 8500 rpm. The shaft did not make contact with the bearing housing. A flow of 5 L/min was obtained at 8000 rpm at a pressure difference of 100 mm Hg. In conclusion, the axial flow blood pump consisting of a hydrodynamic bearing, a magnetic fluid seal, and a brushless DC motor provided contact-free rotation of the impeller without material wear. PMID:17343698

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

2007-03-01

247

Rotordynamics of the intermediate size inducer pump (ISIP)  

Microsoft Academic Search

This report documents the analysis performed to determine the critical shaft speeds for the FFTF Primary Pump with the AI-designed Inducer\\/Impeller attached to the unaltered pump shaft. The results indicate that the proposed arrangement would have a first lateral critical shaft speed of 22.1 Hz (1330 rpm). This speed is 121% of the shaft design speed (1100 rpm). The torsional

Cipra

1978-01-01

248

Lateral fluid forces on whirling centrifugal impeller. I - Theory. II - Experiment in vaneless diffuser  

NASA Astrophysics Data System (ADS)

Lateral fluid forces acting on a rotating centrifugal impeller in whirling motion are analyzed using unsteady potential flow theory. Impellers operating in diffusers with and without vanes are modeled and the fluid forces calculated for different whirl speeds and flow rates. The influences of these parameters are clarified by parametric calculations. The results for whirling impellers operating in vaneless diffusers show that the fluid forces exert a damping effect on the rotor whirling motion at all operating conditions. The results for impellers operating in vaned diffusers or guide vanes show that the time averaged values of fluid forces remain almost unchanged, while there are significant instantaneous fluctuations due to the impeller/guide vane interactions.

Shoji, H.; Ohashi, H.

1987-06-01

249

Numerical simulation of three-dimensional flow field of a paddle-spiral ribbon impeller  

NASA Astrophysics Data System (ADS)

Impeller is the core component of stirrer, which is widely applied in many industrial fields, therefore more and more endeavor is made to design and optimize its structure, in order to improve the efficiency and reliability of stirrer. In this paper, a paddle-spiral ribbon impeller is introduced. 3-D numerical simulation is carried out to study the mixing performances of four different combined forms of this kind of impeller. In the numerical studies, unstructured grid and multi-reference frame (MRF) are used; standard k-? turbulent model and mixture model are adopted to simulate the mixing process of solid-liquid two-phase flow. From the non-steady state simulations, velocity field, mixing time and power consumption are obtained. The results indicate that this kind of impeller is effective for stirring serious fluid. The fist combination form of paddle-spiral ribbon impeller has the best stirring performance.

Zou, W. J.; Zhao, J.; Wang, P. W.; Hu, S. G.

2012-11-01

250

Numerical and Experimental Design Study of a Regenerative Pump  

NASA Astrophysics Data System (ADS)

This paper presents the use of a commercial CFD code to simulate the flow-field within the regenerative pump and compare the CFD results with new experimental data. Regenerative pumps are the subject of increased interest in industry as these pumps are low cost, low specific speed, compact and able to deliver high heads with stable performance characteristics. The complex flow-field within the regenerative pump represents a considerable challenge to detailed mathematical modelling. This paper also presents a novel rapid manufacturing process used to consider the effect of impeller geometry changes on the pump efficiency. Ten modified impeller blade profiles, relative to a standard radial configuration, were evaluated. The CFD performance results demonstrate reasonable agreement with the experimental tests. The CFD results also demonstrate that it is possible to represent the helical flow field for the pump which has only been witnessed in experimental flow visualisation until now. The ability to use CFD modelling in conjunction with rapid manufacturing techniques has meant that more complex impeller geometry configurations can now be assessed with better understanding of the flow-field and resulting efficiency.

Quail, Francis J.; Stickland, Matthew; Scanlon, Thomas

2010-03-01

251

A self-bearing centrifugal blood pump based on induction motor with active and passive magnetic bearings  

Microsoft Academic Search

This paper describes a self-bearing centrifugal blood pump, which can be used as an artificial heart. A flat miniature squirrel-cage induction motor forms the core of the pump. Both the rotor of the induction motor and the impeller of the pump are levitated by passive and active magnetic bearings. The pump structures, design considerations, analysis of the design and time-stepping

Peng Wu; K. J. Tseng

2003-01-01

252

Development of an atraumatic small centrifugal pump for second-generation cardiopulmonary bypass.  

PubMed

A small and light direct-drive centrifugal pump has been developed for cardiopulmonary bypass. In the development process, blood compatibility studies including a hemolysis study, an in vitro fluid dynamic performance study, and in vivo durability and feasibility studies were performed. The centrifugal pump with a 50 mm diameter impeller resulted in almost the same index of hemolysis value as did a Bio-Medicus centrifugal pump. Heat dissipation from the motor was prevented by using a flexible drive cable. Forty-eight-hour sealing durability around the driving axis was accomplished by using a fluoro-rubber V-ring that connected to the hard chrome-plated stainless steel. In vitro and in vivo performances of the pump were satisfactory. Thrombus formation behind the impeller was prevented by using a holed impeller that generated blood flow from the back to the surface of the impeller. Elimination of air during priming procedures was also easier with this modification. This centrifugal pump has one-quarter of the priming volume, size, and weight of magnetically coupled centrifugal pump systems. PMID:1482330

Jikuya, T; Sasaki, T; Aizawa, T; Shiono, M; Glueck, J A; Smith, C P; Feldman, L; Sakuma, I; Sekela, M E; Noda, T

1992-12-01

253

New mechanism to reduce the size of the monopivot magnetic suspension blood pump: direct drive mechanism.  

PubMed

Size reduction of the monopivot magnetic suspension blood pump has been achieved by reducing the size of the magnetic suspension and employing a direct drive mechanism in place of a brushless DC motor and a magnetic coupling. The flow has also been improved using a closed hollow impeller to remove flow obstruction at the inlet and using radial straight vanes to reduce the impeller speed by 30%. Hemolysis testing was conducted for the new models. Results showed that model DD1 presented only a slightly higher level of hemolysis than a regular extracorporeal centrifugal pump. PMID:9212927

Yamane, T; Nishida, M; Kijima, T; Maekawa, J

1997-07-01

254

Feasibility of a TinyPump system for pediatric CPB, ECMO, and circulatory assistance: hydrodynamic performances of the modified pump housing for implantable TinyPump.  

PubMed

The TinyPump is a miniature centrifugal blood pump with an extremely small priming volume of 5 ml, allowing blood transfusion free cardiopulmonary bypass as well as extracorporeal membrane oxygenation in pediatric patients. In this study, a new pump housing with the angled inlet port (25 degrees toward impeller center with respect to the flow axis) was designed to optimize the pump displaced volume and to extend the application of the TinyPump to implantable support The fluid dynamic performance analysis revealed that the head pressure losses increased from 3 to 17 mm Hg in comparison with straight port design as the pump rotational speed increased from 2,000 to 4,000 rpm. This was probably caused by perturbed flow patterns at the site of the inlet bent port area and streamline hitting the off-center of the impeller. No significant effect on pumping efficiency was observed because of modification in inlet port design. Modification in the inflow and outflow port designs together with the drive mechanism reduces the height of the pump system, including the motor, to 27 mm yielding the displaced volume of 68 ml in comparison with 40 mm of the paracorporeal system with the displaced volume of 105 ml. Further analysis in terms of hemolytic as well as antithrombogenic performance will be carried out to finalize the housing design for the implantable version of the TinyPump. PMID:18043159

Yokoyama, Naoyuki; Suzuki, Masaaki; Hoshi, Hideo; Ohuchi, Katsuhiro; Fujimoto, Tetsuo; Takatani, Setsuo

255

Viscous flow on hairy surfaces  

NASA Astrophysics Data System (ADS)

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

Bartenwerfer, M.; Bechert, D. W.

1991-02-01

256

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

257

Axial-Flux Permanent Magnet Brushless Motor for Slim Vortex Pumps  

Microsoft Academic Search

Slim pump for cooling devices play an important role for cooling the electronics apparatus. This paper develops an axial-flux internal rotor type motor for the low-profile vortex pump. The integrated motor-pump structure is composed of an internal permanent magnet (PM) disc rotor and double-sided external coreless stators with windings piled up on the printed circuit board (PCB). The impeller is

Guo-Jhih Yan; Liang-Yi Hsu; Jing-Hui Wang; Mi-Ching Tsai; Xin-Yi Wu

2009-01-01

258

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

259

Experiment of a centrifugal pump during changing speed operation  

NASA Astrophysics Data System (ADS)

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

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

2012-11-01

260

Instability of Thin Viscous Sheets  

Microsoft Academic Search

Thin viscous fluid flows are characterized by a small aspect ratio, i.e., the characteristic thickness is much smaller than the characteristic tangential length scale. They have been used in a variety of manufacturing applications, including curtain coating, film blowing, film casting, extrusion and optical fiber drawing. An asymptotic theory for predicting the thickness distribution and the geometry boundaries of a

Andrey Filippov; Zheming Zheng

2009-01-01

261

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

262

Design of an impeller-mounted electrode array for EIT imaging  

NASA Astrophysics Data System (ADS)

The information content in electrical impedance tomography (EIT) reconstructions is limited by the number of independent impedance measurements acquired for each image frame. This paper describes the design and construction of an electrode array mounted onto a rotating impeller used for mixing processes. By combining the process compliant rotation of the electrodes with a dynamic measurement protocol, a substantial increase in the number of independent measurements is reported. A pitch-blade impeller is built and fitted with four electrodes. A number of challenges associated with operating a rotating electrode array have been addressed including a wireless communications protocol. The impeller has been accurately modelled and measurement simulations closely correspond to those acquired using the array. The apparatus has been used to successfully visualize a test distribution to a consistent standard compared to a conventional EIT electrode array and strategy. Presently, the limiting factor to this approach is the necessary high measurement acquistion rates which lead to restricted impeller velocities.

Murphy, S. C.; Chin, R. K. Y.; York, T. A.

2008-09-01

263

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

PubMed

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

Spicer; Keller; Pratsinis

1996-12-01

264

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

NASA Astrophysics Data System (ADS)

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.

1992-07-01

265

Cryogenic Viscous Compressor Development and Modeling for the ITER Vacuum System  

SciTech Connect

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

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

2011-01-01

266

Numerical Simulation of Tubular Pumping Systems with Different Regulation Methods  

NASA Astrophysics Data System (ADS)

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

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

2010-06-01

267

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

268

Scaleup of a high-shear granulation process using a normalized impeller work parameter.  

PubMed

A method was evaluated to accurately identify the granulation end points of microcrystalline cellulose formulations by monitoring impeller work during high-shear processing. Impeller watt meters were calibrated in situ to a common standard to enable direct comparison of power values between equipment. Integration of the impeller power (watts) versus time (seconds) profile provides an energy parameter (watt seconds) or "work of granulation" for correlation with physical changes in tablet properties and performance. Granulation end points were accurately predicted for 25-, 65-, and 150-liter manufacturing scales on the basis of development work run on 5.0- and 10-liter equipment using work values normalized for the weight of dry powders in the granulator (watt sec/g). The ability to arrive at functionally equivalent granulation end points, in different equipment and at different impeller speeds, was established through comparison of cohesion indexes (slopes of the tablet breaking strength versus compression force profiles) and granulation size distributions determined by sieve analysis. Work measured at the impeller correlated quantitatively with changes in the granulation bulk and tapped densities, average particle size of the finished powders, and cohesion index, independent of granulator make or model. The observed changes in granulation properties, however, did not correlate with individual process variables such as impeller power (watts) or process time. PMID:10934736

Sirois, P J; Craig, G D

2000-01-01

269

Interfacial polymerization encapsulation of a viscous pigment mix: emulsification conditions and particle size distribution.  

PubMed

A viscous organic phase, containing up to 65 per cent solid pigment, was dispersed into water with an emulsifier by a rotor-stator homogenizer and the droplets formed were encapsulated by interfacial polymerization. Microcapsules with volume median diameters d50 ranging from 10 to 25 microns and geometric standard deviation (GSD), from 1.25 to 1.65, were obtained depending on emulsification conditions. Larger impellers gave smaller d50 and slightly narrowed GSD; d50 decreased and GSD increased as volume fraction of dispersed phase is decreased. Higher homogenizer speed and emulsifier concentration decreased d50 but slightly increased GSD. Increasing pigment content in dispersed phase decreased d50 but had little effect on GSD. These effects were assessed quantitatively by fitting an empirical model to the data. PMID:1665852

Tan, H S; Ng, T H; Mahabadi, H K

270

Nonlinear dynamics of viscous droplets  

NASA Astrophysics Data System (ADS)

Nonlinear viscous droplet oscillations are analysed by solving the Navier-Stokes equation for an incompressible fluid. The method is based on mode expansions with modified solutions of the corresponding linear problem. A system of ordinary differential equations, including all nonlinear and viscous terms, is obtained by an extended application of the variational principle of Gauss to the underlying hydrodynamic equations. Results presented are in a very good agreement with experimental data up to oscillation amplitudes of 80% of the unperturbed droplet radius. Large-amplitude oscillations are also in a good agreement with the predictions of Lundgren & Mansour (boundary integral method) and Basaran (Galerkin-finite element method). The results show that viscosity has a large effect on mode coupling phenomena and that, in contradiction to the linear approach, the resonant mode interactions remain for asymptotically diminishing amplitudes of the fundamental mode.

Becker, E.; Hiller, W. J.; Kowalewski, T. A.

1994-01-01

271

Life cycle costs for chemical process pumps  

SciTech Connect

Though construction and startup costs are always a concern, proper investment in equipment and installation will save money down the line. This is particularly important for heavily used items, such as centrifugal pumps, one of the workhouses of the chemical process industries (CPI). By properly sizing and installing a centrifugal pump, the life and efficiency of the pump can be increased. At the same time, maintenance costs can be reduced. When considering a new pump, there are several areas that require attention. The first is the baseplate design. The impeller is another area of concern. The seal chamber, the third area of importance, must be designed for proper heat dissipation and lubrication of seal faces. Lastly, the power end must be considered. Optimum bearing life, effective oil cooling and minimum shaft deflection are all vital. The paper discusses installation costs, operating cost, maintenance cost, seal environment, and extended bearing life.

Urwin, B.; Blong, R.; Jamieson, C.; Erickson, B. [Goulds Pumps, Seneca Falls, NY (United States)

1998-01-01

272

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

273

Fluid dynamic characteristics of the VentrAssist rotary blood pump.  

PubMed

The VentrAssist pump has no shaft or seal, and the device is unique in design because the rotor is suspended passively by hydrodynamic forces, and urging is accomplished by an integrated direct current motor rotor that also acts as the pump impeller. This device has led to many challenges in its fluidic design, namely large flow-blockage from impeller blades, low stiffness of bearings with concomitant impeller displacement under pulsatile load conditions, and very small running clearances. Low specific speed and radial blade off-flow were selected in order to minimize the hemolysis. Pulsatile and steady-flow tests show the impeller is stable under normal operating conditions. Computational fluid dynamics (CFD) has been used to optimize flow paths and reduce net axial force imbalance to acceptably small values. The latest design of the pump achieved a system efficiency of 18% (in 30% hematocrit of red blood cells suspended in phosphate-buffered saline), and efficiency was optimized over the range of operating conditions. Parameters critical to improving pump efficiency were investigated. PMID:10886070

Tansley, G; Vidakovic, S; Reizes, J

2000-06-01

274

An Experimental Study of Cavitation Detection in a Centrifugal Pump Using Envelope Analysis  

Microsoft Academic Search

Cavitation represents one of the most common faults in pumps and could potentially lead to a series of failure in mechanical seal, impeller, bearing, shaft, motor, etc. In this work, an experimental rig was setup to investigate cavitation detection using vibration envelope analysis method, and measured parameters included sound, pressure and flow rate for feasibility of cavitation detection. The experiment

Chek Zin Tan; M. Salman Leong

2008-01-01

275

A novel all-in-one magnetic pump and power harvester design for bio-medical applications  

Microsoft Academic Search

This paper presents a magnetic centrifugal pump with a magnetic power harvester (all-in-one system) for medical applications. The proposed pump is driven by an external rotating magnetic field. To produce pressure and electrical power, an all-in-one device consisting of a pump and a power harvester was designed. It consists of a multi-stage impeller, a disc type NdFeB permanent magnet, and

Sung Hoon Kim; Jaewon Shin; Shuichiro Hashi; Kazushi Ishiyama

2011-01-01

276

Design and evaluation of a single-pivot supported centrifugal blood pump.  

PubMed

In order to develop a centrifugal blood pump that meets the requirements of a long-term, implantable circulatory support device, in this study a single-pivot bearing supported centrifugal blood pump was designed to evaluate its basic performance. The single-pivot structure consisted of a ceramic ball male pivot mounted on the bottom surface of the impeller and a polyethylene female pivot incorporated in the bottom pump casing. The follower magnet mounted inside the impeller was magnetically coupled to the driver magnet mounted on the shaft of the direct current brushless motor. As the motor rotated, the impeller rotated supported entirely by a single-pivot bearing system. The static pump performance obtained in the mock circulatory loop revealed an acceptable performance as a left ventricular assist device in terms of flow and head pressure. The pump flow of 5 L/min against the head pressure of 100 mm Hg was obtained at rotational speeds of 2,000 to 2,200 rpm. The maximum pump flow was 9 L/min with 2,200 rpm. The maximum electrical-to-hydraulic power conversion efficiency was around 14% at pump flows of 4 to 5 L/min. The stability of the impeller was demonstrated at the pump rpm higher than 1,400 with a single-pivot bearing without an additional support at its top. The single-pivot supported centrifugal pump can provide adequate flow and pressure as a ventricular assist device, but its mechanical stability and hemolytic as well as thrombotic performances must be tested prior to clinical use. PMID:11722342

Yoshino, M; Uemura, M; Takahashi, K; Watanabe, N; Hoshi, H; Ohuchi, K; Nakamura, M; Fujita, H; Sakamoto, T; Takatani, S

2001-09-01

277

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

278

Coiling of a viscous filament  

NASA Astrophysics Data System (ADS)

A classic demonstration of fluid buckling is a daily occurence at the breakfast table, where a continuous stream of viscous fluid (honey) is often poured onto a flat surface (toast) from a sufficient height. The thin fluid filament quickly settles into a steady state; near the surface it bends into a helical shape while simultaneously rotating about the vertical and is laid out in a regular coil. This behavior is reminiscent of the coiling of a falling flexible rope. We derive a simple scaling law that predicts the coiling frequency in terms of the filament radius and the flow rate. We also verify this scaling law with the results of experiments.

Samuel, A. D. T.; Ryu, W. S.; Mahadevan, L.

1997-11-01

279

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

280

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

281

Optimal design of splitters attached to turbo blower impeller by RSM  

NASA Astrophysics Data System (ADS)

This paper describes the optimization of the impeller having splitters for a turbo blower. Two design variables, chord of splitter and pitch of splitter, are introduced to enhance the blower performance. Blower pressure and efficiency are selected as an object function, and the optimization of the blower impeller is performed by a response surface method (RSM). Three-dimensional Navier-Stokes equations are introduced to analyze the internal flow of the blower and to find the value of the object function for each case. Throughout the shape optimization of the splitters attached to the impeller in the turbo blower, pressure and efficiency at the design flow condition are successively increased by 5.9 percent and 17.9 percent respectively based on the reference blower. The higher blower efficiency obtained by optimization of impeller having splitters is mainly caused by reducing the number of impeller blades and optimal design of splitters in the blade passage while pressure increase keeps almost the same with the reference blower. For the object function of pressure, pressure increase is obtained at the design and off-design conditions while efficiency keeps higher compared to the reference blower. The enhancement of blower performance is due to the reduction of reverse and circulation flows in the blade passage.

Jang, Choon-Man; Choi, Ka-Ram

2012-06-01

282

Teflon lined process pumps save over $25,000\\/yr in acid regeneration plant  

Microsoft Academic Search

Armco's Eastern Steel Division Works in Ashland, KY includes an acid regeneration plant that uses the spray\\/roaster process to recover hydrochloric acid and high purity iron oxides from spent pickling liquor. Two centrifugal pumps, one operating and one on standby, were used to pump the corrosive and erosive mixture at 175-200°F to the spray nozzles in the roaster. The impeller,

L. Ross; A. Gaines

1982-01-01

283

Air entrainment through viscous liquid.  

NASA Astrophysics Data System (ADS)

We are interested in the impact of a jet of a viscous fluid in a bath of the same liquid. Depending on the speed of the jet, the liquid air interface adopts different shapes 1) at low velocity of the jet, the liquid air interface is not deformed and the base of the jet broadens, hence connecting the two media 2) at intermediate speed, there is an inverse meniscus located on the surface of the bath, and the jet is not deformed. 3) Above a threshold speed a thin sheet of air is dragged into the bath by the jet, in a trumpet-like form. In order to measure properly this speed, we use as experimental set up a rotating solid cylinder half-immersed in a bath. When this cylinder is put in rotation, the film of the viscous fluid dragged at one side of the roller (and at the same speed of the roller) encounters the bath of liquid at the other side with the speed of the roller. At this point, a cusp can be observed, below a threshold velocity Vc. Above this threshold, a film of the upper phase is entrained. We measure Vc and focus on its dependence on the viscosities of the two fluids. We show in particular that Vc depends on the logarithmic of the ratio between the two viscosities.

Lorenceau, Elise; Restagno, Frederic; Quere, David

2002-11-01

284

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

Microsoft Academic Search

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

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

1998-01-01

285

Development of an implantable centrifugal blood pump.  

PubMed

The efficacy of centrifugal pumps for short-term (0-30 days) ventricular support has been widely reported and favorably compared with pulsatile systems. A small, durable, implantable centrifugal blood pump is being developed for medium-term use (up to 6 months). The pump is based on the Medtronic Hemadyne system that has existed in multiple forms over the past 30 years. The pump is approximately the size of a tennis ball, weighs 240 g, and is comprised of a 2.5 cm plastic impeller driven by a radially coupled brushless DC motor. In vitro hydraulic performance was recorded over a wide range of flow conditions on a mock circulatory loop. The pump generated 7 L/min flow against an afterload of 100 mmHg pressure, with a maximum power draw of 10.4 watts. Pulsatile flow was preserved when placed in conjunction with a simulated left ventricle. In vivo testing was performed in 10 healthy sheep for 10-292 hr. Heparin was used to facilitate cannulation, and no anticoagulation was administered after pump implantation. Blood chemistries reflecting hematologic, pulmonary, renal, and hepatic functions were recorded and demonstrated no adverse effects with normal pump operation. Complications were related to kinking of blood conduits and thrombus formation within the cannulae. These results are encouraging and warrant further studies to prove feasibility of this pump as a medium-term implantable ventricular assist device. PMID:1457882

Goldstein, A H; Pacella, J J; Trumble, D R; Clark, R E

286

VIBRATION FIELD PROBLEM RESOLVEDWITH ANALYTICAL DIAGNOSTICSAPPROACHAND INNOVATIVE IMPELLER DESIGN  

Microsoft Academic Search

Several pump units of the same design installed in various locations in the USA with different duties exhibited high vibrations above API limits with process fluids (SG = 0.5 to 0.6) from rated point down to minimum continuous flow. The investigation for root cause was conducted along two parallel paths: experimental and theoretical. On the experimental side a series of

Bruno Schiavello; Giancarlo Cicatelli

287

Hydraulic design and performance analysis of low specific speed centrifugal pump  

NASA Astrophysics Data System (ADS)

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

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

2012-11-01

288

Development of the MEDOS/HIA DeltaStream extracorporeal rotary blood pump.  

PubMed

The DeltaStream blood pump has been developed for extracorporeal circulation with one focus on potential integration into simplified bypass systems (SBS). Its small size and an embedded electric motor are the basic pump properties. A variation of the impeller design has been performed to optimize hydraulic and hematologic characteristics. A simple impeller design was developed which allows flow and pressure generation for cardiopulmonary bypass applications. The option of a pulsatile flow mode for ventricular assist device applications also was demonstrated in vitro. Impeller washout holes were implemented to improve nonthrombogenicity. The pump was investigated for potential thermal hazards for blood caused by the integrated electric motor. It could be demonstrated that there is no thermal risk associated with this design. Durability tests were performed to assess the lifetime of the pump especially with regard to the incorporated polymeric seal. Seal lifetimes of up to 28 days were achieved using different blood substitutes. In animal tests using either the pump as a single device or in an SBS setup, biocompatibility, low hemolysis, and nonthrombogenicity were demonstrated. In summary, the DeltaStream pump shows great potential for different extracorporeal perfusion applications. Besides heart-lung machine and SBS applications, ventricular assist and extracorporeal membrane oxygenation up to several days also appear promising as potential applications. PMID:11403664

Göbel, C; Arvand, A; Eilers, R; Marseille, O; Bals, C; Meyns, B; Flameng, W; Rau, G; Reul, H

2001-05-01

289

Smart Control of Axial Flow Pump Performance by Means of Counter-Rotation  

NASA Astrophysics Data System (ADS)

Turbo pumps have weak points, such as the pumping operation becoming unstable in the rising portion of the head characteristics and/or the cavitation occurring under the intolerably low suction head. These points have been individually overcome in general, since such phenomena originate in essentially different causes. To overcome the above weak points simultaneously, however, we propose a unique pumping system with counter-rotating mechanism and discuss its advantages. This system consists of two-stage impellers and a unique motor with double rotors. The front and rear impellers are driven respectively by the inner and outer rotors of the motor, keeping the relative rotational speed constant and counter-balancing the rotational torque. Such driving conditions not only improve smartly the unstable performance at low discharge but also suppress smartly cavitation at high discharge, under the optimum cooperation with the impeller works and the rotor outputs. The model test proved that there is no rising portion of the head characteristics and that the front impeller speed is gradually decreased with increase of the discharge as if taking the place of the inducer.

Kanemoto, Toshiaki; Kimura, Shingo; Oba, Shin; Satoh, Masako

290

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

291

The Viscous Potential does not Saturate  

Microsoft Academic Search

The transpolar ionospheric potential is generated by both dayside reconnection with the interplanetary magnetic field and a viscous-like interaction with the antisunward flowing solar wind. The reconnection potential increases with increasing IMF magnitude (at a fixed clock angle) while the viscous potential increases with both increasing solar wind velocity and density. It is well known that the magnitude of the

R. E. Lopez; R. J. Bruntz

2010-01-01

292

Viscous fingering in shear thickening silica suspensions  

Microsoft Academic Search

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

Naoki Kagei; Daisuke Kanie; Masami Kawaguchi

2005-01-01

293

Modeling Faraday Excitation of a Viscous Fluid  

Microsoft Academic Search

Abstract Modeling Faraday Excitation of a Viscous Fluid by Bradley Forrest May 2002 Faraday Excitation is the occurrence of growing surface waves when a ?uid is subjected to periodic forcing. Given a ?uid, Faraday Excitation will occur for some, but not all, values of forcing frequency and amplitude. In this thesis, a viscous ?uid is modeled through linear stability analysis

Bradley Forrest; Andrew Bernofi

294

Thin Sheet Formation in Viscous Splash  

Microsoft Academic Search

Ambient air is crucial for creating a splash on smooth dry surfaces for both viscous and inviscid liquids.footnotetextL. Xu, Phys. Rev. E 75, 056316 (2007); L. Xu et al., Phys. Rev. Lett. 94, 184505 (2005). In a viscous splash, the drop initially spreads in the form of a thick lamella until tejt at which time it emits a thin fluid

Michelle Driscoll; Sidney Nagel

2009-01-01

295

Investigation of the washout effect in a magnetically driven axial blood pump.  

PubMed

For a long-term implementation of the magnetically driven CircuLite blood pump system, it is extremely important to be able to ensure a minimum washout flow in order to avoid dangerous stagnation regions in the gap between the impeller and the motor casing as well as near the pivot-axle area at the holes in the impeller's hub. In general, stagnation zones are prone to thrombus formation. Here, the optimal impeller/motor gap width will be determined and the washout flow for different working conditions will be quantitatively calculated. The driving force for this secondary flow is mainly the strong pressure difference between both ends of the gap. Computational fluid dynamics (CFD) and digital particle image velocimetry (DPIV) will be used for this analysis. PMID:18959666

Triep, Michael; Brücker, Christoph; Kerkhoffs, Wolfgang; Schumacher, Oliver; Marseille, Oliver

2008-10-01

296

Research on the pattern of solid-liquid two-phase distribution in chemical process pump  

NASA Astrophysics Data System (ADS)

In order to explore the pattern of solid-liquid two-phase flow distribution in first stage of double-suction impeller and the double volute channel of the HD type petrol-chemical process pump, the flow field in double-suction impeller and double volute is simulated with the CFD software, by taking the Reynolds Averaged Navier Stokes equations as its governing equations, and the standard k-? model for turbulence, derives the pattern of solid particle concentration distribution in the impeller and double volute channel under different initial particle concentrations and different particle diameters. The results show that in the double-suction impeller, solid phase distribution changes a lot along with the increase of initial particle concentration; the concentration near the back side is higher than the face side. Solid particles have the motion trend to the back side of blade in double-suction impeller along with the increase of particle diameters. In double volute channel, solid phase concentration distribution is uneven and solid particle concentration is relatively higher from section 1 to section 8. In the diffusion section, concentration is high in lateral side and low in medial side, the solid particles have the motion trend to the lateral side and the solid particle concentration is relatively higher.

Liu, Y.; Jiang, Y.; Han, Z. J.

2012-11-01

297

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

NASA Astrophysics Data System (ADS)

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

Ji, Min

298

A numerical study of flow-induced noise in a two-dimensional centrifugal pump. Part II. Hydroacoustics  

Microsoft Academic Search

This paper is concerned with determination of the acoustic pressure field in a centrifugal pump. The main noise-generating mechanism is assumed to be the unsteady impeller blade surface forces, which reach a maximum when the flow channel between two consecutive blades is shut off by the volute tongue. The acoustic sources are moving (rotating) dipoles. The strengths of these dipoles

M. A. Langthjem; N. Olhoff

2004-01-01

299

Experimental and numerical investigations of a dynamic cyclone with a rotary impeller  

Microsoft Academic Search

This paper studies a dynamic cyclone with a rotary impeller inside experimentally and numerically. The experiment mainly focuses on the separation efficiency, while the numerical simulation describes the flow field in the dynamic cyclone. The discrete phase model (DPM) is also used to predict the fractional efficiency of the dynamic cyclone, and the predictions are compared with the experimental results.

Jinyu Jiao; Ying Zheng; Jun Wang; Guogang Sun

2008-01-01

300

Research on water simulation experiment of the rotating impeller degassing process  

Microsoft Academic Search

The purification technology by rotating impeller degassing (RID) is becoming one of the important methods to purify molten Al alloys. The degassing efficiency of the RID process is determined by the interaction of many factors. The relationship between technological parameters and degassing efficiency can be defined by building the proper mathematical model which can be used for guidance in practical

Guofa Mi; Shouping Qi; Xiangyu Liu; Jitai Niu

2009-01-01

301

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

302

Development of a compact, sealless, tripod supported, magnetically driven centrifugal blood pump.  

PubMed

In this study, a tripod supported sealless centrifugal blood pump was designed and fabricated for implantable application using a specially designed DC brushless motor. The tripod structure consists of 3 ceramic balls mounted at the bottom surface of the impeller moving in a polyethylene groove incorporated at the bottom pump casing. The follower magnet inside the impeller is coupled to the driver magnet of the motor outside the bottom pump casing, thus allowing the impeller to slide-rotate in the polyethylene groove as the motor turns. The pump driver has a weight of 230 g and a diameter of 60 mm. The acrylic pump housing has a weight of 220 g with the priming volume of 25 ml. At the pump rpm of 1,000 to 2,200, the generated head pressure ranged from 30 to 150 mm Hg with the maximum system efficiency being 12%. When the prototype pump was used in the pulsatile mock loop to assist the ventricle from its apex to the aorta, a strong correlation was obtained between the motor current and bypass flow waveforms. The waveform deformation index (WDI), defined as the ratio of the fundamental to the higher order harmonics of the motor current power spectral density, was computed to possibly detect the suction occurring inside the ventricle due to the prototype centrifugal pump. When the WDI was kept under the value of 0.20 by adjusting the motor rpm, it was successful in suppressing the suction due to the centrifugal pump in the ventricle. The prototype sealless, centrifugal pump together with the control method based on the motor current waveform analysis may offer an intermediate support of the failing left or right ventricle bridging to heart transplantation. PMID:10886073

Yuhki, A; Nogawa, M; Takatani, S

2000-06-01

303

Development of a centrifugal pump with thick blades.  

PubMed

We have developed a centrifugal blood pump with thick impeller blades (60% of pitch) to obtain a small tip clearance. An unshrouded impeller with 6 backward curved thick blades was used to reduce the dead zone between the shroud and upper casing. A streamline angle in volute was uniform in circumferential direction by continuity and angular momentum conservation. To prove the effectiveness of small tip clearance, performance and hemolysis tests were conducted on pumps with a tip clearance of 0.5, 1.5, and 2.0 mm at exit with the blade thickness of 60% of pitch, and with that of 1.0, 2.0, and 2.5 mm at exit with the thickness of 40% of pitch. The results showed that the smaller the tip clearance, the better the hydrodynamic and hemolytic performance. The best result was seen in the pump with tip clearance of 0.5 mm with a blade thickness of 60% of pitch. These results suggest that a centrifugal pump with thick blades and a small tip clearance can be a promising alternative as a cardiopulmonary bypass pump. PMID:10718771

Kim, W G; Chung, C H; Yang, W S; Park, Y N; Kim, H I; Kim, H C; Kang, S H

2000-02-01

304

Special Electro-Hydraulic Valve for Hydro-Viscous Drive Used in Thermal Power Generation Plant  

Microsoft Academic Search

When applied on the pulverized coal blowers or water-feeding pumps which are driven by huge electrical motors in one thermal power generation plant, acting as a kind of the soft start-up device, hydro-viscous drive (HVD) can help to save a lot of energy. The principle and structure of HVD is introduced in the paper. Through theoretical analysis of the HVD

Ning Chen

2009-01-01

305

Generalized Rayleigh'S Problem in Viscous Flows.  

National Technical Information Service (NTIS)

The generalized Rayleigh's problem is considered as the flow of an incompressible viscous fluid produced by an infinitely long cylindrical solid surface, of arbitrary shape, moving parallel to its generators. A broad review of the literature is incorporat...

J. C. Wu T. Y. T. Wu

1966-01-01

306

Hypersonic Viscous Flow Over Large Roughness Elements.  

National Technical Information Service (NTIS)

Viscous flow over discrete or distributed surface roughness has great implications for hypersonic flight due to aerothermodynamic considerations related to laminar-turbulent transition. Current prediction capability is greatly hampered by the limited know...

C. L. Chang M. M. Choudhari

2009-01-01

307

Viscous Drag Reduction for Slender Surface Craft.  

National Technical Information Service (NTIS)

This research investigates viscous drag reduction methods that may be applied to certain marine vehicles. These methods include the injection of microbubbles into the boundary-layer and the use of riblets and various transition-control devices. Experiment...

D. B. Walker

1989-01-01

308

Saddle-node bifurcation of viscous profiles  

NASA Astrophysics Data System (ADS)

Traveling wave solutions of viscous conservation laws, that are associated to Lax shocks of the inviscid equation, have generically a transversal viscous profile. In the case of a non-transversal viscous profile we show by using Melnikov theory that a parametrized perturbation of the profile equation leads generically to a saddle-node bifurcation of these solutions. An example of this bifurcation in the context of magnetohydrodynamics is given. The spectral stability of the traveling waves generated in the saddle-node bifurcation is studied via an Evans function approach. It is shown that generically one real eigenvalue of the linearization of the viscous conservation law around the parametrized family of traveling waves changes its sign at the bifurcation point. Hence this bifurcation describes the basic mechanism of a stable traveling wave which becomes unstable in a saddle-node bifurcation.

Achleitner, Franz; Szmolyan, Peter

2012-10-01

309

Viscous Drag Reduction of Horizontal Plates.  

National Technical Information Service (NTIS)

Methods of reducing the viscous drag created by a two dimensional laminar flow on a horizontal plate were developed. Within Prandtl's boundary layer theory, the two-dimensional dimensionless boundary layer equations were solved by a generalized Crank-Nico...

P. Schaus R. Grundmann

1987-01-01

310

Viscous Remanent Magnetization in Oceanic Basalts.  

National Technical Information Service (NTIS)

Basalt from DSDP site 57 had low magnetic stability and easily acquired viscous remanent magnetization (VRM). The natural remanent magnetization could be explained in magnitude and stability by a VRM acquired in the geomagnetic field during the Brunhes ep...

W. Lowrie

1973-01-01

311

Saddle-node bifurcation of viscous profiles  

PubMed Central

Traveling wave solutions of viscous conservation laws, that are associated to Lax shocks of the inviscid equation, have generically a transversal viscous profile. In the case of a non-transversal viscous profile we show by using Melnikov theory that a parametrized perturbation of the profile equation leads generically to a saddle–node bifurcation of these solutions. An example of this bifurcation in the context of magnetohydrodynamics is given. The spectral stability of the traveling waves generated in the saddle–node bifurcation is studied via an Evans function approach. It is shown that generically one real eigenvalue of the linearization of the viscous conservation law around the parametrized family of traveling waves changes its sign at the bifurcation point. Hence this bifurcation describes the basic mechanism of a stable traveling wave which becomes unstable in a saddle–node bifurcation.

Achleitner, Franz; Szmolyan, Peter

2012-01-01

312

Three-dimensional unsteady flow and forces in centrifugal impellers with circumferential distortion of the outlet static pressure  

SciTech Connect

This paper describes the numerical investigation of the centrifugal impeller response to downstream static pressure distortions imposed by volutes at off-design operations. An unsteady three-dimensional Euler solver with nonreflecting upstream and downstream boundary conditions and phase-lagged periodicity conditions is used for this purpose. The mechanisms governing the unsteady flow field are analyzed. A parametric study shows the influence of the acoustic Strouhal number on the amplitude of the flow perturbations. Radial forces calculated on backward leaned and radial ending centrifugal impellers show nonnegligible influence of the impeller geometry.

Fatsis, A.; Pierret, S.; Braembussche, R. van den [von Karman Inst. for Fluid Dynamics, Rhode-St.-Genese (Belgium). Turbomachinery Dept.

1997-01-01

313

Oxygen transfer into highly viscous media  

Microsoft Academic Search

Highly viscous media often occur in biotechnology, fermentation and food processing industries as well as in chemical and\\u000a pharmaceutical industries. The present paper considers the behavior of aerated highly viscous media employing stirred tank\\u000a reactors, sparged single and multistage tower reactors.\\u000a \\u000a Measuring methods to determine rheological properties, hydrodynamical behavior, power input, and mass transfer as well as\\u000a behavior of single

K. Schügerl

314

Evaluation of main coolant pump shaft cracking  

SciTech Connect

This report presents a review of reactor main coolant pump shaft failures which have occurred in various types of plants and pump designs. The objective of the review was to identify common metallurgical, design and operational considerations which may have contributed to the failures, and which might provide insight into potential repairs and monitoring practices. The review considered Westinghouse PWR main coolant pumps, Byron-Jackson pumps for both BWR and PWR applications, KSB pumps in a US PWR, and Sulzer-Bingham pumps in a US BWR application. All of the above have experienced at least one shaft cracking event, and some have experienced multiple shaft cracking events or total shaft failures. Common factors involved in essentially all of the failures include thermal effects due to purge flow and/or seal cooling, and asymmetric (radial) impeller thrust loads. These have been aggravated in some instances by extended periods of off-design operation; holes, keyways and other stress concentration factors; and less-than-optimal manufacturing processes such as chrome plating and poor surface machining conditions. As a result of this review, several recommendations have been identified for potential industry programs to help resolve the shaft cracking problem and/or to qualify potential remedies. These include programs aimed at reducing the susceptibility of the shafts to the basic failure mechanisms identified as well as programs aimed at improving the industry's basic understanding of the primary loading conditions responsible for the failures.

Brose, W.R.; Chen, K.L.; Kuo, A.Y.; Riccardella, P.C. (Structural Integrity Associates, Inc., San Jose, CA (United States))

1992-02-01

315

Chronic evaluation of a compact nonseal magnet pump as a nonpulsatile pump for long-term use.  

PubMed

Use of a nonpulsatile pump is one of the most interesting approaches in the development of artificial hearts. A centrifugal pump without a seal around the rotating part was evaluated in five goats. The size of the pump is 8.4 cm x phi 7.0 cm, including an electric motor. A polypropylene impeller with four fins on the top of a column in which a magnetic ring is embedded spins by coupling with a rotating magnet outside the housing. In the goats, the pump was placed paracorporeally to provide total left heart bypass at a flow rate of 4.6-7.6 L/min, and activated clotting time was controlled at 200-300 sec by continuous heparin infusion. Although the first three goats died within 3 days due to bleeding, embolism, and a jammed impeller, respectively, a pump could be driven for 14 days in the fourth goat, and another pump with a rotational control feedback system ran for 32 days in the fifth goat. Plasma free hemoglobin levels were 13.8 +/- 4.3 mg/dl and 9.5 +/- 2.5 mg/dl, and platelet counts were 53.8 +/- 24.7 x 10(4)/mm3 and 62.0 +/- 22.0 x 10(4)/mm3 after 12 hours and 7 days pumping, respectively. No thrombus was observed in the blood chamber in the last two cases. In conclusion, this pump has possibilities as a nonpulsatile pump for long-term use. PMID:1751130

Taenaka, Y; Tatsumi, E; Sakaki, M; Sasaki, E; Masuzawa, T; Nakatani, T; Akagi, H; Goto, M; Matsuo, Y; Inoue, K

316

Development of a miniature intraventricular axial flow blood pump.  

PubMed

A new intraventricular axial flow blood pump has been designed and developed as a totally implantable left ventricular assist device (LVAD). This pump consists of an impeller combined with a guide-vane, a tube housing, and a DC motor. The pump is introduced into the LV cavity through the LV apex, and the outlet cannula is passed antegrade across the aortic valve. Blood is withdrawn from the LV through the inlet ports at the pump base, and discharged to the ascending aorta. Our newly developed axial flow pump system has the following advantages: 1) it is a simple and compact system, 2) minimal blood stasis both in the device and the LV cavity, 3) minimal blood contacting surface of the pump, 4) easy accessibility with a less invasive surgical procedure, and 5) low cost. A pump flow > 5 L/min was obtained against 100 mmHg differential pressure in the mock circulatory system. The pump could produce a passive pulsatile flow effect with a beating heart more efficiently than other non-pulsatile pumps because of minimal pressure drop and inertia along the bypass tract. Anatomic fit studies using dissected hearts of dilated cardiomyopathy (DCM) cadavers showed that this pump could smoothly pass through the aortic valve without any interference with mitral valve function. Recently, a dynamic pressure groove bearing and a miniature lip seal have been developed. The dynamic pressure groove bearing has a simple structure and acts as a pressure resistant sealing mechanism.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:8268533

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

317

Numerical analysis of the inner flow field of a biocentrifugal blood pump.  

PubMed

Implantable ventricular assist devices have been regarded as a promising instrument in the clinical treatment of patients with severe heart failures. In this article, a three-dimensional model of the Kyoto-NTN magnetically suspended centrifugal blood pump was generated and a computational fluid dynamics solution of the inner flow field of the pump including the static pressure distributions, velocity profiles, and the shear stress distributions of the blood was presented. The results revealed that reverse flow generally occurred in the impeller blade channels during the operation of the pump, due to the imbalance of the flow and the pressure gradient generated in the blade channels. The flow pattern at the exit of the blade channels was varying with its angular positions in the pump. The reverse flow at the exit of the impeller blade channels was found to be closely related with the static pressure distribution in the volute passage. Higher pressure in the volute caused severe backflow from the volute into the blade channels. To clarify the effects of a moving impeller on the blood, shear stresses of the blood in the pump were investigated according to the simulation results. The studies indicated that at the beginning of the splitter plate and the cutwater, the highest shear stress exceeded 700 Pa. At other regions such as the inlet and outlet of the impeller blade channels and some regions in the volute passage, shear stresses were found to be about 200 Pa. These areas are believed to have a high possibility of rendering blood trauma. PMID:16734599

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

2006-06-01

318

Temporal Evolution of the 3-D Flow Field In a Mixing Tank with a Two-Bladed Impeller  

Microsoft Academic Search

The evolution of the 3-D flow field inside a cylindrical mixing vessel was measured using 3-D Cinematic Particle Tracking Velocimetry. The mixing vessel consisted of a cylindrical chamber with a two-bladed impeller axially centered in the vessel. The impeller was a simple paddle wheel-type and its height in the vessel could be externally adjusted. The fluid inside the chamber was

Woong-Chul Choi; Yann G. Guezennec

1998-01-01

319

Appraisal of Fluid Dynamic Efficiency of Retreated-Blade and Turbofoil Impellers in Industrial-Size CSTRs  

Microsoft Academic Search

In this work, we examine the performances of two different impellers produced for glass-lined industrial vessel installations. Starting from an experimental evaluation of the power number- Reynolds number curve, we exploit fully three-dimensional, time-dependent fluid dynamic simulations to identify the optimal operating conditions for the widely used retreated-blade impeller and the newer turbofoil turbine. We calculate the power consumption, stirring

Marina Campolo; Alfredo Soldati

2002-01-01

320

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

NASA Astrophysics Data System (ADS)

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

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

2013-03-01

321

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

2012-02-22

322

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

323

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

324

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

325

A geometric modeling and five-axis machining algorithm for centrifugal impellers  

Microsoft Academic Search

Unlike in three-axis machining, in five-axis machining the flexibility in tool orientation in space is extremely high. To obtain the full advantage of five-axis machining, the computer-aided manufacturing (CAM) system must have similar flexibility in tool orientation. Unfortunately, most CAM systems that support five-axis machining do not provide the required flexibility.A centrifugal impeller is a perfect example of a part

Tsau Tar; S. D. R. Senadhera; K. Pole; J. R. Duflou

1997-01-01

326

LDA measurements and CFD simulations of flow generated by impellers in mechanically agitated reactors  

Microsoft Academic Search

The turbulent flow produced by various designs of axial flow impellers in a stirred vessel was measured using a laser Doppler\\u000a anemometer (LDA). Flat-bottomed cylindrical vessels of diameters 0.3 m and 0.5 m provided with 4 baffles ofT\\/10 width were used as the reactors. The standard two-equation (k-?) turbulence model was used to numerically simulate the flow (both 2D and

J B Joshi; A K Sahu; P Kumar

1998-01-01

327

Modeling and Diagnostics of Heavy Impeller Gyroscopic Rotor with Tilting Pad Journal Bearings  

Microsoft Academic Search

\\u000a The work presents the study of dynamics of heavy impeller rotor and failure diagnostics of tilting-pad journal bearings. The\\u000a started rubbing process in the bearings at resonance and increased rubbing phenomenon in both bearings by measurement of radial\\u000a gaps, were identified experimentally in situ. The rotational speed was established when gravitational force became dominant\\u000a compared to rotor gyroscopic force. Rotating

V. Barzdaitis; M. Bogdevi?ius; R. Didžiokas; M. Vasylius

328

ELECTROMAGNETIC PUMP  

DOEpatents

This patent reiates to electromagnetic pumps for electricity-conducting fluids and, in particular, describes several modifications for a linear conduction type electromagnetic interaction pump. The invention resides in passing the return conductor for the current traversing the fiuid in the duct back through the gap in the iron circuit of the pump. Both the maximum allowable pressure and the efficiency of a linear conduction electromagnetic pump are increased by incorporation of the present invention.

Pulley, O.O.

1954-08-17

329

Simulating elliptic flow with viscous hydrodynamics  

NASA Astrophysics Data System (ADS)

In this work we simulate a viscous hydrodynamical model of noncentral Au-Au collisions in 2+1 dimensions, assuming longitudinal boost invariance. The model fluid equations were proposed by Öttinger and Grmela [Grmela, M., and Öttinger, H. C., Phys. Rev. E, 56, 6620 (1997)]. Freeze-out is signaled when the viscous corrections become large relative to the ideal terms. Then viscous corrections to the transverse momentum and differential elliptic flow spectra are calculated. When viscous corrections to the thermal distribution function are not included, the effects of viscosity on elliptic flow are modest. However, when these corrections are included, the elliptic flow is strongly modified at large pT. We also investigate the stability of the viscous results by comparing the nonideal components of the stress tensor (?ij) and their influence on the v2 spectrum to the expectation of the Navier-Stokes equations (?ij=-?). We argue that when the stress tensor deviates from the Navier-Stokes form the dissipative corrections to spectra are too large for a hydrodynamic description to be reliable. For typical Relativistic Heavy Ion Colloder initial conditions this happens for ?/s?0.3.

Dusling, K.; Teaney, D.

2008-03-01

330

The Viscous Potential does not Saturate  

NASA Astrophysics Data System (ADS)

The transpolar ionospheric potential is generated by both dayside reconnection with the interplanetary magnetic field and a viscous-like interaction with the antisunward flowing solar wind. The reconnection potential increases with increasing IMF magnitude (at a fixed clock angle) while the viscous potential increases with both increasing solar wind velocity and density. It is well known that the magnitude of the reconnection potential is limited. As the transverse IMF grows to sufficient magnitude, the transpolar ionospheric potential saturates and ceases to increase as the IMF increases. On the other hand, simulations using the Lyon-Fedder-Mobarry simulation code of the value of the viscous component of the potential do not exhibit the saturation effect. The viscous potential in the simulation increases to values beyond the reconnection saturation value at extreme values of the solar wind velocity (>2400 km/s). In addition to the simulation results, we present observations from DMSP of the transpolar ionospheric potential that are consistent with our simulations results for the solar wind conditions under which the observations were made, suggesting that in fact during periods of extreme solar wind speeds, such as occurred during the 1859 Carrington event or the August 1972 event, the viscous interaction could be a very significant factor in solar wind-magnetosphere coupling.

Lopez, R. E.; Bruntz, R. J.

2010-12-01

331

Insulin Pumps  

MedlinePLUS

... in place. The insulin pump is not an artificial pancreas (because you still have to monitor your blood glucose level), but pumps can help some people achieve better control, and many people prefer this continuous system of insulin delivery over injections. Pumps can be ...

332

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

PubMed

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

Houchin, Tiffany L; Hanley, Thomas R

2004-01-01

333

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

SciTech Connect

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

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

1996-04-15

334

Experimental study and numerical simulation of the solid-phase particles' influence on outside characteristics of slurry pump  

NASA Astrophysics Data System (ADS)

At present solid-liquid two-phase flow pump faces two big problems: the low efficiency, the short life, then the concentration of the conveyed solid-phase media are the important factors which affect the outside characteristics about this two phase flow pump. This article presents the outside characteristics' experimental research and internal flow field's simulation analysis on AH type slurry pump which is product by Shijiazhuang Shi- Jiang pump industry, discusses the flow rule in the impeller, and summaries the influence of the solid phased particles' concentration on the performance of the slurry pump's outside characteristics. At last, the rationality and accuracy of the numerical calculation method are verified through the way of comparing numerical simulation with experimental results in this two phase flow pump. And the relation between slurry pump's outside characteristics and granule concentration is summarized, which provided theoretical guidance for the slurry pump's optimization design and selection.

Wang, P. W.; Zhao, J.; Zou, W. J.; Hu, S. G.

2012-11-01

335

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

336

Use minimum flow data to prolong centrifugal pump life  

SciTech Connect

Environmental and safety concerns and, in the US, the consequences of failing of meet EPA regulations are intensifying efforts to improve the reliability of pumping equipment. A critical step toward achieving this goal is eliminating cavitation, and the resulting impeller and shaft vibrations, which, ultimately, cause seal and bearing failure. In centrifugal pumps, cavitation results when they run at very low flow rates, as can happen during unplanned upsets or interruptions. This particularly true since many centrifugal pumps are now controlled by automatic valves in their discharge lines. The problem can be prevented by providing a small bypass line to the pump`s suction source, to control temperature rise in the pump. Usually, the minimum flow is so low that the bypass loop can be kept open without detracting from the pump`s efficiency. It needn`t require a flow control valve or any special instrumentation, but will let the pump run at a comfortable flow, even with the control valve closed. This paper describes a method to determine minimum thermal flow to prevent cavitation.

Reynolds, J.A.

1996-03-01

337

Computational fluid dynamics analysis of hydrodynamic bearings of the VentrAssist rotary blood pump.  

PubMed

The computational fluid dynamics (CFD) package CFX-TASCflow was applied to simulate the flows through the blood pump hydrodynamic bearings. The three-dimensional flow patterns through the bearings were predicted and the hydraulic performance analyzed. The computations were carried out at 3 axial positions of the pump impeller. Net lift force away from the nearer part of the housing increased when the impeller moved closer to this part. Radial force and drag force were also found. Separated flows were observed at the leading and trailing edge of the bearing gap. To test the CFD package, a series of two-dimensional computations were also carried out for various bearing geometries. The results were compared with published experimental data. PMID:10886071

Qian, Y; Bertram, C D

2000-06-01

338

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

339

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

340

Dilepton production from a viscous QGP  

Microsoft Academic Search

This work calculates the first correction to the leading order qq¯ dilepton production rates due to shear viscosity in an expanding gas. The modified rates are integrated over the space–time history of a viscous hydrodynamic simulation of RHIC collisions. The net result is a hardening of q? spectrum with the magnitude of the correction increasing with invariant mass. We argue

Kevin Dusling; Shu Lin

2008-01-01

341

Viscous hypersonic flows for various aerophysical models  

Microsoft Academic Search

The results of mathematical simulation of hypersonic air flow past a sphere with allowance for chemical nonequilibrium and ionization are presented. The calculated data are obtained on the basis of a numerical solution of the Navier-Stokes equations and the hypersonic viscous shock layer equations. The equilibrium radiation temperature of the body surface, the pressure, and the shock wave detachment are

I. V. Egorov; V. S. Nikol'skii

1996-01-01

342

Ion metal synthesis in viscous organic matter  

Microsoft Academic Search

The viscosity of the irradiated target as new parameter was introduced in ion implantation physics of organic matter. It was experimentally shown that using this parameter one enables to monitor the process of ion synthesis of thin granular impurity films. As an example, the results of high-dose implantation of Co+ and Ag+ ions in viscous epoxy experimenting stages of cure

I. B. Khaibullin; R. I. Khaibullin; S. N. Abdullin; A. L. Stepanov; Yu. N. Osin; V. V. Bazarov; S. P. Kurzin

1997-01-01

343

One-Way Reel with Viscous Drag.  

National Technical Information Service (NTIS)

The one-way reel is for use in the field of air-launched towed targetry. The viscous drag is obtained from a bracking mechanism in the form of a circular disk which rotates in a chamber filled with a silicone oil.

E. J. McQuillen

1965-01-01

344

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

345

Viscous Glass Sealants for SOFC Applications.  

National Technical Information Service (NTIS)

Two series of silicate glasses that contain gallium as the primary critical component have been identified and optimized for viscous sealing of solid oxide fuel cells operating from 650 to 850DGC. Both series of glass sealants crystallize partially upon h...

S. Misture

2012-01-01

346

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

347

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

2013-08-19

348

NASA research on viscous drag reduction II  

Microsoft Academic Search

An assessment is made of determinations from NASA research on viscous drag reduction for aircraft, which extends to both laminar flow control and turbulent drag reduction methods. Attention is given to achievements in natural and suction-induced laminar flow control, hybrid systems incorporating both principles, turbulent drag reduction by means of low momentum fluid injection from discrete tangential slots, large eddy

D. M. Bushnell

1984-01-01

349

Viscous drag reduction of horizontal plates  

Microsoft Academic Search

Methods of reducing the viscous drag created by a two dimensional laminar flow on a horizontal plate were developed. Within Prandtl's boundary layer theory, the two-dimensional dimensionless boundary layer equations were solved by a generalized Crank-Nicolson finite difference method. In order to reduce the integrated skin friction coefficient, a slightly disturbed outer velocity distribution was given to the plate. According

Ph. Schaus; R. Grundmann

1987-01-01

350

VHD: Viscous pseudo-Newtonian accretion  

NASA Astrophysics Data System (ADS)

VHD is a numerical study of viscous fluid accretion onto a black hole. The flow is axisymmetric and uses a pseudo-Newtonian potential to model relativistic effects near the event horizon. VHD is based on ZEUS-2D (Stone & Norman 1992) with the addition of an explicit scheme for the viscosity.

McKinney, Jonathan C.; Gammie, Charles F.

2013-06-01

351

Aircraft viscous drag reduction using riblets  

Microsoft Academic Search

The last two decades have seen considerable research activity on the use of riblets for viscous drag reduction. Experimental results concerning the performance of 3M riblets on airfoils, wings and wing-body or aircraft configurations at different speed regimes are reviewed; these applications bring in additional effects like pressure gradients and three dimensionality. In addition to drag reduction, aspects of altered

P. R. Viswanath

2002-01-01

352

Vibration assessment for thrombus formation in the centrifugal pump.  

PubMed

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

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

1997-04-01

353

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

PubMed

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

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

1999-06-01

354

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

2011-04-26

355

Submersible pumps  

Microsoft Academic Search

The electric submersible pump has been used with success in the petroleum industry for more than 45 yr. With this unit, it has been possible to produce oil directly or indirectly which, in any other production method would not be economically feasible. The electric submersible pump consists of 5 basic elements beginning at the bottom: the motor; the electric cable;

Loper

1975-01-01

356

Nature's pumps  

Microsoft Academic Search

Although diverse in both form and function, the fluid-forcing devices in organisms have many of the capabilities and limitations of pumps of human design. Nature's pumps certainly look quite different from those of our technology, but all of them perform the same task. The author examines a few of these with an eye toward technological parallels and the two functional

Steven Vogel

1994-01-01

357

Single stage high pressure centrifugal slurry pump  

DOEpatents

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

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

1984-03-27

358

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

SciTech Connect

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

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

1993-07-01

359

The elastic–viscous–plastic method revisited  

NASA Astrophysics Data System (ADS)

In this paper, we show that one of the most widely used methods to solve the non-linear viscous–plastic (VP) sea ice rheology, the elastic–viscous–plastic (EVP) method, generates artificial linear bands of high deformation that may be confounded with real linear kinematic features observed in the Arctic ice pack. These numerical artefacts are easily filtered out by using a slightly different regularization of the internal stress. In addition, the EVP method is reinterpreted as an iterative solver and a clear distinction appears between the numerical and physical parameters. Two numerical parameters determine the stability and accuracy of the method and are adjusted to avoid the noisy ice deformation fields frequently observed with the EVP method in nearly rigid ice areas. This study also confirms the unsatisfactory numerical convergence of the EVP method and investigates the effects of the numerical parameters on sea ice deformation, internal stress and velocity fields obtained with unconverged solutions.

Bouillon, Sylvain; Fichefet, Thierry; Legat, Vincent; Madec, Gurvan

2013-11-01

360

Upwind differencing for viscous flow computations  

NASA Astrophysics Data System (ADS)

High-resolution upwind differencing has become a popular feature of recently-developed Euler methods for compressible inviscid flow simulations. This feature was straightforwardly extended for the evaluation of convective terms of the Navier-Stokes equations. Recent study of total variation diminishing (TVD) type high-resolution upwind schemes proved that dissipation-like terms introduced by these upwind schemes such as Roe's flux difference splitting automatically become small in the viscous layers. Here, numerical computations using this Roe's upwind scheme with MUSCL interpolation are conducted, and the results are compared with the typical central differencing results. The computed results indicate that the present upwind differencing shows better resolution than the central differencing in both inviscid region and viscous region.

Fujii, Kozo; Takanashi, Susumu; Matsushima, Kisa

1988-12-01

361

Viscous damping of perforated planar micromechanical structures  

PubMed Central

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

Homentcovschi, D.; Miles, R.N.

2008-01-01

362

Viscous damping of perforated planar micromechanical structures.  

PubMed

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

Homentcovschi, D; Miles, R N

2005-01-01

363

Stability of a falling viscous sheet  

NASA Astrophysics Data System (ADS)

Falling films can be found in various processes of the food, glass and polymer industry. We study thin viscous films flowing vertically under the action of gravity, when poured from a slit. The lateral sides are unconstrained and the stretching effect of gravity induces a narrowing of the film in the horizontal direction, by Poisson's effect. This leads to compressive stress for some range of parameters, and we study the associated viscous buckling instabilities. A local stability analysis is used to characterized the flow parameters leading to potential instabilities. A global stability analysis is carried out, and an eigenvalue problem is solved numerically. This is implemented using the finite-element method with high order derivatives.

Perdigou, Claude; Pfingstag, Gilles; Audoly, Basile; Boudaoud, Arezki

2013-03-01

364

Viscous dissipative effects in isotropic brane cosmology  

NASA Astrophysics Data System (ADS)

We consider the dynamics of a viscous cosmological fluid in the generalized Randall-Sundrum model for an isotropic brane. To describe the dissipative effects we use the Israel-Hiscock-Stewart full causal thermodynamic theory. In the limiting case of a stiff cosmological fluid with pressure equal to the energy density, the general solution of the field equations can be obtained in an exact parametric form for a cosmological fluid with a constant bulk viscosity and with a bulk viscosity coefficient proportional to the square root of the energy density, respectively. The obtained solutions describe generally noninflationary brane worlds, starting from a singular state. During this phase of evolution the comoving entropy of the Universe is an increasing function of time, and thus a large amount of entropy is created in the brane world due to viscous dissipative processes.

Chen, Chiang-Mei; Harko, T.; Mak, M. K.

2001-12-01

365

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

2013-05-02

366

Dynamic toughness in elastic nonlinear viscous solids  

Microsoft Academic Search

This work addresses the interrelationship among dissipative mechanisms—material separation in the fracture process zone (FPZ), nonelastic deformation in the surrounding background material and kinetic energy—and how they affect the macroscopic dynamic fracture toughness as well as the limiting crack speed in strain rate sensitive materials. To this end, a micromechanics-based model for void growth in a nonlinear viscous solid is

S. Tang; T. F. Guo; L. Cheng

2009-01-01

367

Viscous Overstability in Saturn's B Ring  

Microsoft Academic Search

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

Heikki Salo; Jürgen Schmidt; Frank Spahn

2001-01-01

368

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

SciTech Connect

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

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

2010-01-29

369

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

NASA Astrophysics Data System (ADS)

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

Moore, John; Moore, Joan G.

1988-06-01

370

Fingers and Toes in Miscible Viscous Flows  

NASA Astrophysics Data System (ADS)

The displacement of a more viscous fluid by a less viscous one in a porous medium produces complex fingering patterns. To study this phenomenon a Hele-Shaw geometry is used in which the gap-averaged equations for flow between two parallel plates has the same form as Darcy's law for flow in porous media. Our experiments use a radial Hele-Shaw cell as well as a two dimensional porous medium of densely packed granular beads between two circular glass plates, to study viscous fingering in miscible fluids. For immiscible fluids it is known that the most-unstable wavelength for interface growth depends on surface tension, viscosity difference, velocity and plate spacing. In contrast, we find that for miscible fluids the large-scale structure (i.e., the ratio of finger length to overall size of the pattern) is set entirely by the viscosity ratio rather than the viscosity difference of the two fluids. We further investigate the role played by other dimensionless parameters in determining the fine structure and evolution of these fingering patterns in the two geometries.

Ramachandran, Radha; Bischofberger, Irmgard; Nagel, Sidney

2012-02-01

371

Viscous Glass Sealants for SOFC Applications  

SciTech Connect

Two series of silicate glasses that contain gallium as the primary critical component have been identified and optimized for viscous sealing of solid oxide fuel cells operating from 650 to 850°C. Both series of glass sealants crystallize partially upon heat treatment and yield multiphase microstructures that allow viscous flow at temperatures as low as 650°C. A fully amorphous sealant was also developed by isolating, synthesizing and testing a silicate glass of the same composition as the remnant glassy phase in one of the two glass series. Of ~40 glasses tested for longer than 500 hours, a set of 5 glasses has been further tested for up to 1000h in air, wet hydrogen, and against both yttria-stabilized zirconia and aluminized stainless steel. In some cases the testing times reached 2000h. The reactivity testing has provided new insight into the effects of Y, Zr, and Al on bulk and surface crystallization in boro-gallio-silicate glasses, and demonstrated that at least 5 of the newly-developed glasses are viable viscous sealants.

Scott Misture

2012-09-30

372

Investigation on centrifugal impeller in an axial-radial combined compressor with inlet distortion  

NASA Astrophysics Data System (ADS)

Assembling an axial rotor and a stator at centrifugal compressor upstream to build an axial-radial combined compressor could achieve high pressure ratio and efficiency by appropriate size augment. Then upstream potential flow and wake effect appear at centrifugal impeller inlet. In this paper, the axial-radial compressor is unsteadily simulated by three-dimensional Reynolds averaged Navier-Stokes equations with uniform and circumferential distorted total pressure inlet condition to investigate upstream effect on radial rotor. The results show that span-wise nonuniform total pressure distribution is generated and radial and circumferential combined distortion is formed at centrifugal rotor inlet. The upstream stator wake deflects to rotor rotation direction and decreases with blade span increases. Circumferential distortion causes different separated flow formations at different pitch positions. The tip leakage vortex is suppressed in centrifugal blade passages. Under distorted inlet condition, flow direction of centrifugal impeller leading edge upstream varies evidently near hub and shroud but varies slightly at mid-span. In addition, compressor stage inlet distortion produces remarkable effect on blade loading of centrifugal blade both along chordwise and pitchwise.

Li, Du; Yang, Ce; Zhao, Ben; Zhou, Mi; Qi, Mingxu; Zhang, Jizhong

2011-12-01

373

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

SciTech Connect

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

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

1997-12-31

374

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

375

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

376

ION PUMP  

DOEpatents

An ion pump and pumping method are given for low vacuum pressures in which gases introduced into a pumping cavity are ionized and thereafter directed and accelerated into a quantity of liquid gettering metal where they are absorbed. In the preferred embodiment the metal is disposed as a liquid pool upon one electrode of a Phillips ion gauge type pump. Means are provided for continuously and remotely withdrawing and degassing the gettering metal. The liquid gettering metal may be heated if desired, although various combinations of gallium, indium, tin, bismuth, and lead, the preferred metals, have very low melting points. A background pressure of evaporated gettering metal may be provided by means of a resistance heated refractory metal wick protruding from the surface of the pcol of gettering metal.

Milleron, N.

1961-01-01

377

Electrokinetic pump  

DOEpatents

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

378

Over the shaft fuel pumping system  

SciTech Connect

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

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

1991-02-05

379

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 g/100 l with the impeller in the down-mode and a bearing clearance of 0.1 mm. Further refinement in the bearing and magnetic coupler are required to improve the hemolytic performance of the pump. The durability of the needle-type hydrodynamic bearing and antithrombotic performance of the pump will be performed before clinical applications. The tiny centrifugal blood pump meets the flow requirements necessary to support the circulation of pediatric patients. PMID:16322718

Takatani, Setsuo; Hoshi, Hideo; Tajima, Kennichi; Ohuchi, Katsuhiro; Nakamura, Makoto; Asama, Junichio; Shimshi, Tadahiko; Yoshikawa, Masaharu

380

Biosynthesis of high molecular weight hyaluronic acid by Streptococcus zooepidemicus using oxygen vector and optimum impeller tip speed.  

PubMed

The potential use of n-dodecane and n-hexadecane as oxygen vectors for enhancing hyaluronic acid (HA) biosynthesis by Streptococcus zooepidemicus ATCC 39920 was investigated using a 2-L stirred-tank bioreactor equipped with helical ribbon or Rushton turbine impellers. The volumetric fraction of the oxygen vector influenced the gas-liquid volumetric oxygen transfer coefficient (K(L)a) positively. Batch HA fermentation with 1% (v/v) n-dodecane or 0.5% (v/v) n-hexadecane addition was carried out at different impeller tip speeds. Even though cell growth was lower in the fermentation with oxygen vector addition, the HA productivity and molecular weight were higher when compared to the fermentation without oxygen vector at low impeller tip speed. The highest HA concentration (4.25 gHA/l) and molecular weight (1.54 × 10(7) Da) were obtained when 0.5% (v/v) n-hexadecane and 0.785 m/s impeller tip speed of helical ribbon were used. PMID:22608992

Lai, Zee-Wei; Rahim, Raha Abdul; Ariff, Arbakariya B; Mohamad, Rosfarizan

2012-05-19

381

Dispersion coefficients and settling velocities of solids in slurry vessels stirred with different types of multiple impellers  

Microsoft Academic Search

Equipment dealing with stirred suspensions are broadly used in the process industry. Out of the various aspects affecting their performance, solids distribution is addressed in this paper. The behaviour of a tank of high aspect ratio stirred with multiple impellers of three types is analysed. The purpose is to acquire fundamental information on parameters useful for their description, namely the

D. Pinelli; G. Montante; F. Magelli

2004-01-01

382

The application of a strain gauge technique to the measurement of the power characteristics of five impellers  

Microsoft Academic Search

The work described in this paper establishes the accuracy with which the power number can be measured within a mixing vessel and presents measurements for five impellers (Rushton, “bucket”, 45°-pitched blade, 60°-pitched blade and hyperboloid) as a function of rotational speed. The technique uses strain gauges and the telemetric transmission of the strain and is, therefore, more accurate than methods

M. F. W. Distelhoff; J. Laker; A. J. Marquis; J. M. Nouri

1995-01-01

383

Calculation of three-dimensional viscous flow in hydrodynamic torque converters  

SciTech Connect

A numerical method for calculating three-dimensional, steady or unsteady, incompressible, viscous flow is described. The conservation equations for mass and momentum and the equations of the {kappa}-{epsilon} turbulence model are solved with a finite volume method on nonorthogonal boundary-fitted grids. The method employs cell-centered variable arrangement and Cartesian velocity components. The SIMPLE algorithm is used to calculate the pressure and to enforce mass conservation. The computer code is vectorizable as far as possible to achieve an optimal performance on modern vector computers. Results of steady flow calculations in the guide vane, the pump rotor, and the turbine rotor and of the unsteady interaction simulation of the pump and the turbine of a one-stage one-phase non-automotive hydrodynamic torque converter are presented.

Schulz, H.; Greim, R.; Volgmann, W. [Ruhr-Univ. Bochum (Germany). Lehrstuhl fuer Fluidenergiemaschinen

1996-07-01

384

Flow visualization in a centrifugal blood pump with an eccentric inlet port.  

PubMed

Flow visualization analysis was applied to the Baylor/Miwatec centrifugal artificial heart to evaluate its fluid dynamic characteristics regarding antithrombogenicity. An eccentric vortex was found both in the upper and the lower gaps of the impeller, which is supposed to be caused by the eccentric inlet port. Therefore, one-way flow toward the outlet is formed and washes the pivot. The combination of an eccentric vortex and a pivot bearing that is washed is unique to the Baylor/Miwatec pump. For the male pivots exposed to periodic wash, the minimum shear rate around the bottom pivot was estimated to be 650/s, which is higher than the threshold for thrombus formation shown by other studies. The wall shear rate at the impeller bottom surface was found to be larger in the top contact mode than in the bottom contact mode. PMID:15153149

Yamane, Takashi; Kodama, Takayuki; Yamamoto, Yoshiro; Shinohara, Toshiyuki; Nosé, Yukihiko

2004-06-01

385

Magnetically suspended rotary blood pump with radial type combined motor-bearing.  

PubMed

A magnetically suspended centrifugal blood pump is being developed with a combined motor-bearing for long-term ventricular assist systems. The combined motor-bearing actively suspends a rotor in a radial direction to deal with radial force unbalance in the pump and rotates the rotor by using the electric magnetic field. Therefore, the pump has no mechanical parts such as bearings of the motor and has a long lifetime. The developed pump consists of a thin rotor with a semi open-type 6 vane impeller and a stator to suspend and rotate the rotor. The rotor has 4-pole permanent magnets on the circumferential surface. The outer diameter and the thickness of the rotor are 60 mm and 8 mm, respectively. Axial movement and tilt of the rotor are restricted by passive stability based on the thin rotor structure. Radial movements of the rotor, such as levitation in radial direction and rotation, are controlled actively by using electric magnets of the stator. The electric magnet coils to produce levitation and rotation forces are constructed on the periphery stator. The p +/- 2-pole algorithm and the synchronous motor mechanism are adopted to levitate and rotate the rotor. The radial gap between the rotor and the stator is 1 mm. A closed-loop circuit filled with water was connected to the developed pump to examine the basic performance of the pump and the magnetic suspension system. Maximum rotational speed, flow rate, and head were 2,800 rpm, 11 L/min, and 270 mm Hg, respectively. The rotor with the impeller could be suspended completely during the entire pumping process. We conclude the pump with the combined motor-bearing has sufficient performance for the blood pump. PMID:10886067

Masuzawa, T; Kita, T; Matsuda, K; Okada, Y

2000-06-01

386

Fluctuating pressures in pump diffuser and collector scrolls, part 1  

NASA Astrophysics Data System (ADS)

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

Sloteman, Donald P.

1989-08-01

387

Forced Spreading and Coalescence of Viscous Drops  

NASA Astrophysics Data System (ADS)

This study investigates the dynamics of spreading and coalescence of sessile droplets on a surface, a process important in applications such as inkjet printing, spray coating, and flooding of fuel cells. We use a simple microfluidic device to control the spreading and merging processes. Droplet shape, diameter and maximum height are monitored as functions of time. We compare the dynamics with existing scaling models modified to incorporate time dependent volume, and we extend these models to describe the scaling behavior of the liquid bridge growing between merging droplets on a surface. The experiments agree well with the expected scaling incorporating capillary, gravity, and viscous forces.

Anna, Shelley; Kang, Pilgyu; Shojaei-Zadeh, Shahab; Appleby, Christine

2009-11-01

388

Quadratic finite elements and incompressible viscous flows.  

SciTech Connect

Pressure stabilization methods are applied to higher-order velocity finite elements for application to viscous incompressible flows. Both a standard pressure stabilizing Petrov-Galerkin (PSPG) method and a new polynomial pressure projection stabilization (PPPS) method have been implemented and tested for various quadratic elements in two dimensions. A preconditioner based on relaxing the incompressibility constraint is also tested for the iterative solution of saddle point problems arising from mixed Galerkin finite element approximations to the Navier-Stokes equations. The preconditioner is demonstrated for BB stable elements with discontinuous pressure approximations in two and three dimensions.

Dohrmann, Clark R.; Gartling, David K.

2005-01-01

389

Folding of viscous sheets and filaments  

NASA Astrophysics Data System (ADS)

We consider the nonlinear folding behavior of a viscous filament or a sheet under the influence of an external force such as gravity. Everyday examples of this phenomenon are provided by the periodic folding of a sheet of honey as it impinges on toast, or the folding of a stream of shampoo as it falls on one's hand. To understand the evolution of a fold, we formulate and solve a free-boundary problem for the phenomenon, give scaling laws for the size of the folds and the frequency with which they are laid out, and verify these experimentally.

Skorobogatiy, M.; Mahadevan, L.

2000-12-01

390

Collision of microswimmers in a viscous fluid.  

PubMed

We investigate the effects of boundary conditions on the surface of self-propelled spherical swimmers moving in a viscous fluid with a low Reynolds number. We first show that collisions between the swimmers are impossible under the commonly used no-slip conditions. Next we demonstrate that collisions do occur if the more general Navier boundary conditions, allowing for a finite slip on the surface that produces drag, are imposed on the boundary of swimmers. The presence of a small inertia for each swimmer does not influence whether collisions occur between swimmers. PMID:23767618

Potomkin, M; Gyrya, V; Aranson, I; Berlyand, L

2013-05-09

391

Adaptive remeshing for viscous incompressible flows  

NASA Astrophysics Data System (ADS)

This paper presents an adaptive finite element procedure for solving viscous incompressible flows. The methodology is based on adaptive remeshing for steady state problems. The Navier-Stokes equations for an incompressible fluid are solved in primitive variables by an Uzawa algorithm using a highly accurate element. The efficiency and convergence rate of the adaptive strategy are evaluated by solving problems with known analytical solutions. Finally the methodology is applied to problems of practical interest and predictions are compared with experimental measurements. The use of the proposed adaptive is shown to lead to improved accuracy of the finite element predictions.

Hetu, Jean-Francois; Pelletier, Dominique H.

1990-06-01

392

An analysis of a viscous dissipation flow  

NASA Astrophysics Data System (ADS)

A laminar Couette-Poiseullie flow of a Newtonian fluid is considered and heat transfer characteristics are analyzed, attention being given to the effect of viscous dissipation for the thermal boundary condition that both the plates being kept at specified and at different constant heat fluxes. The momentum equation is solved to obtain the velocity profile in such a way that it consists of the velocity of the upper moving plate and in turn the energy equation is solved to yield temperature distribution and Nusselt number. Interesting results are observed based on the influence of various parameters which are in terms of Brinkman number, dimensionless velocity and heat flux ratio.

Sheela-Francisca, J.; Tso, C. P.

2012-06-01

393

Computation of weakly-compressible highly-viscous liquid flows  

Microsoft Academic Search

We introduce a second-order accurate time-marching pressure-correction algorithm to accommodate weakly-compressible highly-viscous liquid flows at low Mach number. As the incompressible limit is approached (Ma ? 0), the consistency of the compressible scheme is highlighted in recovering equivalent incompressible solutions. In the viscous-dominated regime of low Reynolds number (zone of interest), the algorithm treats the viscous part of the equations

M. F. Webster; I. J. Keshtiban; F. Belblidia

2004-01-01

394

VISCOUS CORRECTIONNS TO SPECTRA, ELLIPTIC FLOW, AND HBT RADII.  

SciTech Connect

I compute the first viscous correction to the thermal distribution function. With this correction, I calculate the effect of viscosity on spectra, elliptic flow, and HBT radii. Indicating the breakdown of hydrodynamics, viscous corrections become of order one for 1.5GeV. Viscous corrections to HBT radii are particularly large and reduce the outward and longitudinal radii. This reduction is a direct consequence of the reduction in longitudinal pressure.

TEANEY,D.

2002-07-18

395

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

NASA Astrophysics Data System (ADS)

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

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

2012-11-01

396

In vitro evaluation of the TandemHeart pediatric centrifugal pump.  

PubMed

The pediatric TandemHeart pump is being developed for short-term circulatory support of patients varying in size from 2 to 40 kg. The pump withdraws blood from the left atrium via cannula inserted percutaneously, either through the right internal jugular vein or transhepatically, and pumps the blood back into the arterial system via the carotid or femoral artery. High resolution stereolithography (SLA) was used to create an upper housing and impeller design, which were assembled into a functional pump prototype. Pressure-flow characteristics of the pump were determined in a blood analogue solution and compared with the pressure-flow requirements of the intended cannulation. At 5,500 rpm, the pump was able to generate 0.4 L/min of flow with a pressure rise of 325 mm Hg and 2.0 L/min with a pressure rise of 250 mm Hg. The hydraulic performance of the pump will enable at least 50% of cardiac output when the arterial cannula is placed in the carotid artery. The hemolysis of the TandemHeart pediatric pump at 5,500 rpm was compared with the BP-50 pediatric centrifugal pump in vitro using bovine blood flowing at 0.4 L/min against 250 mm Hg. The TandemHeart pump produced a similar increase in plasma free hemoglobin levels during the duration of the 6 hour test. PMID:18043160

Svitek, Robert G; Smith, Douglas E; Magovern, James A

397

DIFFUSION PUMP  

DOEpatents

A high-vacuum diffusion pump is described, featuring a novel housing geometry for enhancing pumping speed. An upright, cylindrical lower housing portion is surmounted by a concentric, upright, cylindrical upper housing portion of substantially larger diameter; an uppermost nozzle, disposed concentrically within the upper portion, is adapted to eject downwardly a conical sheet of liquid outwardly to impinge upon the uppermost extremity of the interior wall of the lower portion. Preferably this nozzle is mounted upon a pedestal rising coaxially from within the lower portion and projecting up into said upper portion. (AEC)

Levenson, L.

1963-09-01

398

Insulin pumps.  

PubMed

The last year has seen a continued uptake of insulin pump therapy in most countries. The USA is still a leader in pump use, with probably some 40% of type 1 diabetic patients on continuous subcutaneous insulin infusion (CSII), but the large variation in usage within Europe remains, with relatively high use (>?15%) in, for example, Norway, Austria, Germany and Sweden and low use (pump procedures, and clear referral pathways for the pump candidate from general practitioner or general hospital to specialist pump centre. There are now several comprehensive national guidelines on CSII use (see ATTD Yearbook 2009) but more work needs to be done in unifying uptake and ensuring all those who can benefit do so. Technology developments recently include increasing use of pumps with continuous glucose monitoring (CGM) connectivity (see elsewhere in this volume) and the emergence of numerous manufacturers developing so-called 'patch pumps', often for the type 2 diabetes market. Interestingly, the evidence base for CSII in this group is not well established, and for this reason the selected papers on CSII in this section include several in this area. The use of CSII in diabetic pregnancy is a long-established practice, in spite of the lack of evidence that it is superior to multiple daily injections (MDI), and few randomised controlled trials have been done in recent years. Several papers in this field this year continue the debate about the usefulness of CSII in diabetic pregnancy and are reviewed here. It is pleasing to see more research on the psychosocial aspects of CSII during the year, both from the point of view of how psychological beliefs influence outcomes on CSII (is there a type of patient who does particularly well or poorly on CSII?) and how CSII affects psychological factors like mood, behaviour and quality of life. Quality of life is a difficult topic with doubts that the instruments always capture the aspects of quality of life important to the patient, and there have been conflicting results over the years about whether CSII alters quality of life. Patients in the clinic usually say that it does, and more evidence for quality of life improvement in pump therapy is reviewed here. PMID:21323808

Pickup, J

2011-02-01

399

Suppressing Viscous Drop Splashing with Surface Roughness  

NASA Astrophysics Data System (ADS)

The splashing of a liquid drop on a smooth, dry surface depends on a host of factors: the speed, surface tension, viscosity and size of the drop, but also, surprisingly, the pressure and molecular weight of the surrounding gas.footnotetext L. Xu, W.W. Zhang, S.R. Nagel, PRL 94, 184505 (2005).^,footnotetext L. Xu, PRE 75, 056316 (2007). In the case of a viscous drop splashing on a smooth surface, a thin sheet of fluid is first ejected from the rim of the expanding drop and then breaks up into droplets to form a splash.footnotetextM. Driscoll et al., BAPS DFD AG.00005 (2008). When the surface is rough, different behavior, known as prompt splashing, may also be observed.^2,footnotetext L. Xu, L. Barcos, and S.R. Nagel, PRE 76 066311 (2007). Here we explore the splashing of a viscous liquid as the surface roughness, Ra, is varied. We find that a small degree of roughness, Ra< 1 ?m, can completely suppress the thin-sheet ejection occurring on smooth surfaces. The degree of roughness necessary for this suppression decreases with increasing viscosity. In some cases, the roughness is great enough to suppress the thin sheet, but insufficient to produce a prompt splash, thus suppressing the splash entirely.

Strandburg-Peshkin, Ariana; Driscoll, Michelle; Nagel, Sidney

2009-11-01

400

Vortex shedding from edges including viscous effects  

NASA Astrophysics Data System (ADS)

This paper describes results obtained by using the inviscid Cloud-in-Cell vortex method to model the vortex sheet which is shed and rolls up from a single sharp edge. There is good agreement between these results and previous (Pullin 1978) computations of the development of the sheet in impulsively started incompressible inviscid flow. The Cloud-in-Cell method has been modified to include viscous diffusion calculated by finite differences on the mesh to give a mixed Eulerian-Lagrangian Navier-Stokes solver. This method has been shown to model the diffusing free vortex and the Stokes boundary layer quite accurately. It is used to compute impulsively started flow past sharp right-angled edges and edges with small rounding. The effect of viscous diffusion on the development of the shed vortex is discussed. The method is also used to study the effect of rounding on the vortex shedding from a right-angled edge in oscillatory flow. This problem is particularly important in determining the roll damping and hence response of certain types of ship hull in waves. It is shown that the strength and effect of the shed vortices rapidly decrease as the ratio of the edge radius to the oscillation amplitude increases, and that at larger values of this ratio the mode of shedding changes from two vortices per cycle from one edge to a more complicated mode. The computed results are compared with flow visualisation using dye and neutrally buoyant particles in water flow around an oscillating edge.

Graham, J. M. R.; Cozens, P. D.

1988-09-01

401

Experimental study of the pressure fluctuations in a pump turbine at large partial flow conditions  

NASA Astrophysics Data System (ADS)

Frequent shifts of output and operating mode require a pump turbine with excellent stability. Current researches show that large partial flow conditions in pump mode experience positive-slope phenomena with a large head drop. The pressure fluctuation at the positive slope is crucial to the pump turbine unit safety. The operating instabilities at large partial flow conditions for a pump turbine are analyzed. The hydraulic performance of a model pump turbine is tested with the pressure fluctuations measured at unstable operating points near a positive slope in the performance curve. The hydraulic performance tests show that there are two separated positive-slope regions for the pump turbine, with the flow discharge for the first positive slope from 0.85 to 0.91 times that at the maximum efficiency point. The amplitudes of the pressure fluctuations at these unstable large partial flow conditions near the first positive slope are much larger than those at stable operating condtions. A dominant frequency is measured at 0.2 times the impeller rotational frequency in the flow passage near the impeller exit, which is believed to be induced by the rotating stall in the flow passage of the wicket gates. The test results also show hysteresis with pressure fluctuations when the pump turbine is operated near the first positive slope. The hysteresis creates different pressure fluctuations for those operation points even though their flow rates and heads are similar respectively. The pressure fluctuation characteristics at large partial flow conditions obtained by the present study will be helpful for the safe operation of pumped storage units.

Ran, Hongjuan; Luo, Xianwu; Zhu, Lei; Zhang, Yao; Wang, Xin; Xu, Hongyuan

2012-11-01

402

An implantable centrifugal blood pump for long term circulatory support.  

PubMed

A compact centrifugal blood pump was developed as an implantable left ventricular assist system. The impeller diameter is 40 mm and the pump dimensions are 55 x 64 mm. This first prototype was fabricated from titanium alloy, resulting in a pump weight of 400 g including a brushless DC motor. Weight of the second prototype pump was reduced to 280 g. The entire blood contacting surface is coated with diamond like carbon to improve blood compatibility. Flow rates of over 7 L/min against 100 mmHg pressure at 2,500 rpm with 9 W total power consumption have been measured. A newly designed mechanical seal with a recirculating purge system ("Cool-Seal") is used as a shaft seal. In this seal system, seal temperature is kept under 40 degrees C to prevent heat denaturation of blood proteins. Purge fluid also cools the pump motor coil and journal bearing. The purge fluid is continuously purified and sterilized by an ultrafiltration filter incorporated into the paracorporeal drive console. In vitro experiments with bovine blood demonstrated an acceptably low hemolysis rate (normalized index of hemolysis = 0.005 +/- 0.002 g/100 L). In vivo experiments are currently ongoing using calves. Via left thoracotomy, left ventricular apex-descending aorta bypass was performed utilizing a PTFE (Polytetrafluoroethylene) vascular graft, with the pump placed in the left thoracic cavity. In two in vivo experiments, pump flow rate was maintained at 5-8 L/min, and pump power consumption remained stable at 9-10 W. All plasma free hemoglobin levels were measured at < 15 mg/dl. The seal system has demonstrated good seal capability with negligible purge fluid consumption (< 0.5 ml/ day). Both animals remain under observation after 162 and 91 days of continuous pump function. PMID:9360134

Yamazaki, K; Litwak, P; Kormos, R L; Mori, T; Tagusari, O; Antaki, J F; Kameneva, M; Watach, M; Gordon, L; Umezu, M; Tomioka, J; Koyanagi, H; Griffith, B P

403

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

PubMed

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

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

2011-01-01

404

Design and investigation of working components of low-specific-speed electric pumps  

SciTech Connect

In developing the working elements of the electric pumps the following technical requirements have been taken into account: the cavitation properties and the efficiencies of the working elements of the pumps investigated must be significantly higher than those of the type KhG series produced pumps; the cantilever impeller with cylindrical vanes must be cast from stainless steels; spiral type branches must be made by casting in sand molds; the feed to the stage must be 10% greater than design because of the need to withdraw part of the liquid to cool the electric motor and to lubricate the bearings; the working elements for the same feed rate must be unified as much as possible in terms of the inlet and impeller seal diameters, in terms of the inlet and outlet branches. The working elements of the pumps were tested on water on a SKTBN experimental rig in accordance with the requirements of GOST 6134-71. The results of the tests carried out show that outlets with side spirals for low specific speed stages with account taken of their advantages relative to vibration and noise characteristics are more profitable in comparison with outlets having radial shapes of spirals.

Smutin, N.V.

1982-11-01

405

Numerical simulation of hydrodynamics in a pump-turbine at off-design operating conditions in turbine mode  

NASA Astrophysics Data System (ADS)

The hydrodynamics of a reduced-scaled model of a radial pump-turbine is investigated under off-design operating conditions, involving runaway and "S-shape" turbine brake curve at low positive discharge. It is a low specific speed pump-turbine machine of Francis type with 9 impeller blades and 20 stay vanes as well as 20 guide vanes. The computational domain includes the entire water passage from the spiral casing inlet to the draft tube outlet. Completely structured hexahedral meshes generated by the commercial software ANSYS-ICEM are employed. The unsteady incompressible simulations are performed using the commercial code ANSYS-CFX13. For turbulence modeling the standard k-? model is applied. The numerical results at different operating points are compared to the experimental results. The predicted pressure amplitude is in good agreement with the experimental data and the amplitude of normal force on impeller is in reasonable range. The detailed analysis reveals the onset of the flow instabilities when the machine is brought from a regular operating condition to runaway and turbine break mode. Furthermore, the rotating stall phenomena are well captured at runaway condition as well as low discharge operating condition with one stall cell rotating inside and around the impeller with about 70% of its frequency. Moreover, the rotating stall is found to be the effect of rotating flow separations developed in several consecutive impeller channels which lead to their blockage. The reliable simulation of S-curve characteristics in pump-turbines is a basic requirement for design and optimization at off-design operating conditions.

Yan, J. P.; Seidel, U.; Koutnik, J.

2012-11-01

406

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

NASA Astrophysics Data System (ADS)

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

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

2012-11-01

407

Violations of conservation laws in viscous liquid dynamics  

Microsoft Academic Search

The laws expressing conservation of momentum and energy apply to any isolated system, but these laws are violated for for highly viscous liquids under laboratory conditions because of the unavoidable interactions with the measuring equipment over the long times needed to study the dynamics. Although particle number conservation applies strictly for any liquid, the solidity of viscous liquids implies that

J. C. Dyre

2007-01-01

408

Viscous Flow at the Boundary of a Porous Material.  

National Technical Information Service (NTIS)

The boundary region between an open viscous flow and a porous matrix has been examined for parallel flow by numerical solution of the viscous flow equations. Results for simple shear flow are consistent with analytic theory and experimental results on a s...

V. O'Brien

1975-01-01

409

Runge-Kutta Methods and Viscous Wave Equations.  

National Technical Information Service (NTIS)

We study the numerical time integration of a class of viscous wave equations by means of Runge-Kutta methods. The viscous wave equation is an extension of the standard second-order wave equation including advection-diffusion terms differentiated in time. ...

J. G. Verwer

2008-01-01

410

Cluster Heating by Viscous Dissipation of Sound Waves  

Microsoft Academic Search

We simulate the effects of viscous dissipation of waves that are generated by active galactic nucleus (AGN) activity in clusters of galaxies. We demonstrate that the amount of viscous heating associated with the dissipation of these waves can offset radiative cooling rates in cooling flow clusters of galaxies. This heating mechanism leads to spatially distributed and approximately symmetrical dissipation. The

Mateusz Ruszkowski; Marcus Brüggen; Mitchell C. Begelman

2004-01-01

411

Influence of viscous, gravitational, and capillary forces on DNAPL saturation  

Microsoft Academic Search

Four dense nonaqueous phase liquids (DNAPLs) -- bromoform, chlorobenzene, tetrachloroethylene, and trichloroethylene -- were used to investigate the influence of viscous, gravitational, and capillary forces on DNAPL saturation in a natural aquifer sand. The relative magnitudes of these forces are expressed in terms of two dimensionless groups, the Capillary Number (N{sub Ca}), defined as the ratio of the viscous force

Helen E. Dawson; Paul V. Roberts

1997-01-01

412

The viscous flow on surfaces with longitudinal ribs  

Microsoft Academic Search

The viscous sublayer on surfaces with long straight ribs aligned in the streamwise direction is investigated theoretically. The velocity distributions on various surface configurations are calculated by using conformal mapping. The geometries investigated include sawtooth profiles with triangular and trapezoidal grooves and profiles with thin blade-shaped ribs, ribs with rounded edges, and ribs having sharp ridges and U-shaped grooves. Viscous

D. W. Bechert; M. Bartenwerfer

1989-01-01

413

Distortion and Necking of a Viscous Inclusion in Stokes Flow  

Microsoft Academic Search

Spence & Wilmott (1988) considered the deformation of a slender inclusion of highly-viscous fluid in a Stokes flow of less viscous fluid, and derived a coupled pair of equations to describe its evolution. The equations possess self-preserving solutions for elliptical inclusions, previously known from the work of Bilby et al. (1975, 1976) and Bilby & Kolbuszewski (1977). In the present

D. A. Spence; P. W. Sharp

1989-01-01

414

Sloshing analysis of viscous liquid storage tanks  

SciTech Connect

The effect of viscosity on the sloshing response of tanks containing viscous liquids is studied using the in-house finite element computer code, FLUSTR-ANL. Two different tank sizes each filled at two levels, are modeled, and their dynamic responses under harmonic and seismic ground motions are simulated. The results are presented in terms of the wave height, and pressures at selected nodes and elements in the finite element mesh. The viscosity manifests itself as a damping effect, reducing the amplitudes. Under harmonic excitation, the dynamic response reaches the steady-state faster as the viscosity value becomes larger. The fundamental sloshing frequency for each study case stays virtually unaffected by an increase in viscosity. For the small tank case, a 5% difference is observed in the fundamental frequency of the smallest (1 cP) and the highest (1000 cP) viscosity cases considered in this study. The fundamental frequencies of the large tank are even less sensitive.

Uras, R.Z.

1995-07-01

415

A new dielectric effect in viscous liquids  

NASA Astrophysics Data System (ADS)

An accurate experimental and theoretical study has been performed about a phenomenon, not previously reported in the literature, occurring in highly viscous liquids: the formation of a definite pipe structure induced by the passage of a heavy body, this structure lasting for quite a long time. A very rich phenomenology (including mechanical, optical and structural effects) associated with the formation of the pipe has been observed in different liquids. Actually, the peculiar dynamical evolution of that structure does not appear as a trivial manifestation of standard relaxation or spurious effects. In particular, we have revealed different time scales during the evolution of the pipe and a non-monotonous decrease of the persistence time with decreasing viscosity (with the appearance of at least two different maxima). We put forward a microscopic model, consistent with the experimental data, where the pipe behaves as a "dielectric shell" whose time evolution is described through a simple thermodynamical approach, predicting several properties effectively observed.

Capano, Vittorio; Esposito, Salvatore; Salesi, Giovanni

2013-06-01

416

Nonequilibrium relativistic thermodynamics in bulk viscous cosmology  

NASA Astrophysics Data System (ADS)

Three different approaches to the relativistic thermodynamics of imperfect fluids are compared: the second-order causal theory of Israel and Stewart (IS), the phenomenological extension of the IS theory proposed by Maartens and Méndez (MM), and the recently developed GENERIC formalism of Grmela and Öttinger. All theories are applied to the case of dissipative cosmology, with bulk viscosity as the only dissipative phenomenon. The MM theory as well as GENERIC give an upper bound on the bulk viscous stress, whereas there is none in the IS theory. In a flat Robertson-Walker universe, the relationship between the different approaches is illustrated for the special case of a relativistic Boltzmann gas. Far away from equilibrium we find qualitatively different behavior, indicating that care should be taken when using the IS theory in this regime.

Ilg, Patrick; Öttinger, Hans Christian

2000-01-01

417

Formulating viscous hydrodynamics for large velocity gradients  

SciTech Connect

Viscous corrections to relativistic hydrodynamics, which are usually formulated for small velocity gradients, have recently been extended from Navier-Stokes formulations to a class of treatments based on Israel-Stewart equations. Israel-Stewart treatments, which treat the spatial components of the stress-energy tensor {tau}{sub ij} as dynamical objects, introduce new parameters, such as the relaxation times describing nonequilibrium behavior of the elements {tau}{sub ij}. By considering linear response theory and entropy constraints, we show how the additional parameters are related to fluctuations of {tau}{sub ij}. Furthermore, the Israel-Stewart parameters are analyzed for their ability to provide stable and physical solutions for sound waves. Finally, it is shown how these parameters, which are naturally described by correlation functions in real time, might be constrained by lattice calculations, which are based on path-integral formulations in imaginary time.

Pratt, Scott [Department of Physics and Astronomy, Michigan State University East Lansing, Michigan 48824-1321 (United States)

2008-02-15

418

Particle wall collisions in a viscous fluid  

NASA Astrophysics Data System (ADS)

This paper presents experimental measurements of the approach and rebound of a particle colliding with a wall in a viscous fluid. The particle's trajectory was controlled by setting the initial inclination angle of a pendulum immersed in a fluid. The resulting collisions were monitored using a high-speed video camera. The diameters of the particles ranged from 3 to 12 mm, and the ratio of the particle density to fluid density varied from 1.2 to 7.8. The experiments were performed using a thick glass or Lucite wall with different mixtures of glycerol and water. With these parameters, the Reynolds number defined using the velocity just prior to impact ranged from 10 to approximately 3000. A coefficient of restitution was defined from the ratio of the velocity just prior to and after impact.

Joseph, G. G.; Zenit, R.; Hunt, M. L.; Rosenwinkel, A. M.

2001-04-01

419

Coupling relativistic viscous hydrodynamics to Boltzmann descriptions  

SciTech Connect

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

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

2010-10-15

420

Galloping instability of viscous shock waves  

NASA Astrophysics Data System (ADS)

Motivated by physical and numerical observations of time oscillatory “galloping”, “spinning”, and “cellular” instabilities of detonation waves, we study Poincaré Hopf bifurcation of traveling-wave solutions of viscous conservation laws. The main difficulty is the absence of a spectral gap between oscillatory modes and essential spectrum, preventing standard reduction to a finite-dimensional center manifold. We overcome this by direct Lyapunov Schmidt reduction, using detailed pointwise bounds on the linearized solution operator to carry out a nonstandard implicit function construction in the absence of a spectral gap. The key computation is a space-time stability estimate on the transverse linearized solution operator reminiscent of Duhamel estimates carried out on the full solution operator in the study of nonlinear stability of spectrally stable traveling waves.

Texier, Benjamin; Zumbrun, Kevin

2008-07-01

421

Viscous-inviscid interaction with higher-order viscous-flow equations  

SciTech Connect

The partially parabolic, or parabolized, Navier-Stokes equations for laminar flow, and the corresponding Reynolds equations for turbulent flow, are coupled with an inviscid-flow solution procedure to develop a viscous inviscid interaction method for three-dimensional flow that cannot be treated by means of the classical boundary-layer equations. This study provides a detailed overview of the approach for general three-dimensional flows and presents results of applications to some test cases. The Reynolds equations are derived in nonorthogonal curvilinear coordinates, with velocity components along the coordinate directions, using vector techniques. This approach differs from the commonly-used tensor methods but serves to establish a connection with the more-familiar boundary-layer methods. The K-epsilon model is used for turbulent flows. The partially-parabolic viscous-flow equations are solved using an implicit finite-difference scheme and the SIMPLER algorithm for pressure-velocity coupling. The inviscid-flow solutions are obtained with a conforming panel, source-panel method. Interaction between the viscous and inviscid regions is accounted for using the displacement-body concept.

Yoo, S.

1986-01-01

422

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

Microsoft Academic Search

The objective of this work was to assess the effect of agitation rate and impeller type in two mechanically stirred sequencing batch reactors: one containing granulated biomass (denominated ASBR) and the other immobilized biomass on polyurethane foam (denominated AnSBBR). Each configuration, with total volume of 1m3, treated 0.65m3 sanitary wastewater at ambient temperature in 8-h cycles. Three impeller types were

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

2010-01-01

423

The Role of Library and Information Services in Supporting Students in Resource?based Learning: some findings of the IMPEL2 Project  

Microsoft Academic Search

The IMPEL2 Project is a JISC?funded eLib Project based at the University of Northumbria at Newcastle. It has been engaged in a 2?year (1996?98) investigation of organisational and cultural change in the increasingly electronic environment in UK Higher Education HE. The selection of Case Study sites was purposive; some had participated in the previous IMPEL1 study. A qualitative methodology, using

Maureen Jackson; Sandra Parker

1998-01-01

424

Injection pumps  

NASA Astrophysics Data System (ADS)

Injection pumps are simple devices with no moving parts but with complex flow including free-shear and boundary layers combined with shocks and possible multiphase flow. In spite of this, they are susceptible to simple control volume analyses. Here, we examine the extent to which these analyses represent optimal performance for a steam injector. We develop performance measures for 2D RANS computations and experiments.

Schultz, William; Han, Bosuk; Johnsen, Eric

2011-11-01

425

Measurement of rotary pump flow and pressure by computation of driving motor power and speed.  

PubMed

Measurement of pump flow and pressure by ventricular assist is an important process, but difficult to achieve. On one hand, the pump flow and pressure are indicators of pump performance and the physiologic status of the receptor, meanwhile providing a control basis of the blood pump itself. On the other hand, the direct measurement forces the receptor to connect with a flow meter and a manometer, and the sensors of these meters may cause haematological problems and increase the danger of infection. A novel method for measuring flow rate and pressure of rotary pump has been developed recently. First the pump performs at several rotating speeds, and at each speed the flow rate, pump head and the motor power (voltage x current) are recorded and shown in diagrams, thus obtaining P (motor power)-Q (pump volume) curves as well as P-H (pump head) curves. Secondly, the P, n (rotating speed) values are loaded into the input layer of a 3-layer BP (back propagation) neural network and the Q and H values into the output layer, to convert P-Q and P-H relations into Q = f (P,n) and H = g (P, n) functions. Thirdly, these functions are stored by computer to establish a database as an archive of this pump. Finally, the pump flow and pressure can be computed from motor power and speed during animal experiments or clinical trials. This new method was used in the authors' impeller pump. The results demonstrated that the error for pump head was less than 2% and that for pump flow was under 5%, so its accuracy is better than that of non-invasive measuring methods. PMID:11315655

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

426

Effects of paddle impeller geometry on power input and mass transfer in small-scale animal cell culture vessels.  

PubMed

Process scaleup for stirred-tank animal cell cultures such as suspension and microcarrier cultures often begins at the bench scale in small spinner vessels. In order to initiate process development under the proper conditions, it is essential to know the physical conditions under which the cells are grown. In this article, power inputs and surface oxygen transfer rates to culture medium in 500-mL Corning spinner vessels were determined as a function of the impeller geometry, impeller height, and agitation speed. The results obtained indicate that power dissipation dependency differs from literature correlations and may compromise scale up at constant power input from these vessels. These results are of general utility to researchers using small-scale vessels. PMID:18588209

Aunins, J G; Woodson, B A; Hale, T K; Wang, D I

1989-11-01

427

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

PubMed

A new model of blood pump for cardiopulmonary bypass (CPB) application has been developed and evaluated in our laboratories. Inside the pump housing is a spiral impeller that is conically shaped and has threads on its surface. Worm gears provide an axial motion of the blood column. Rotational motion of the conical shape generates a centrifugal pumping effect and improves pumping performance. One annular magnet with six poles is inside the impeller, providing magnetic coupling to a brushless direct current motor. In order to study the pumping performance, a mock loop system was assembled. Mock loop was composed of Tygon tubes (Saint-Gobain Corporation, Courbevoie, France), oxygenator, digital flowmeter, pressure monitor, electronic driver, and adjustable clamp for flow control. Experiments were performed on six prototypes with small differences in their design. Each prototype was tested and flow and pressure data were obtained for rotational speed of 1000, 1500, 2000, 2500, and 3000 rpm. Hemolysis was studied using pumps with different internal gap sizes (1.35, 1.45, 1.55, and 1.7 mm). Hemolysis tests simulated CPB application with flow rate of 5 L/min against total pressure head of 350 mm Hg. The results from six prototypes were satisfactory, compared to the results from the literature. However, prototype #6 showed the best results. Best hemolysis results were observed with a gap of 1.45 mm, and showed a normalized index of hemolysis of 0.013 g/100 L. When combined, axial and centrifugal pumping principles produce better hydrodynamic performance without increasing hemolysis. PMID:21595709

Leme, Juliana; Fonseca, Jeison; Bock, Eduardo; da Silva, Cibele; da Silva, Bruno Utiyama; Dos Santos, Alex Eugênio; Dinkhuysen, Jarbas; Andrade, Aron; Biscegli, José F

2011-05-01

428

One thousand dollar assist heart pump for patients from developing countries.  

PubMed

In spite of continuous improvements in device design and applications, the profound use of heart pump has been limited because of its high price. The available clinically applied heart pump costs mostly about 100 thousands US Dollars. The author has since long tried to develop a heart pump costing only 1000 Dollars for recovery or bridge to heart transplantation therapies. The device is a radially driven centrifugal pump with a brush-less DC motor and a streamlined impeller. Its bearing is rolling bearing using 4 to 6 needles, manufactured by special wear-proof polythene with super-high-molecular weight, thus the service life achieves more than 10 years. To avoid thrombus formation, a special purge system is introduced to the bearing, allowing the saline with heparin to be infused through the bearing into the pump. The bearing, therefore, keeps working in the saline, and absolutely no thrombus will be formed along the bearing. Animal experiments demonstrated that a 30 mL fluid infusion per hour is enough to prevent thrombus formation. With these improvements, the impeller pump has continuously run for 14 months in the laboratory, and no bearing wear can be measured. The device, weighing 150 g, is fully implantable, consumes approximately 9.6 W, delivers a 9Lmin-1 blood flow against a 120 mmHg mean pressure, and reaches a highest total efficiency of 24.7% for the motor (including the controller) and the pump. The device has been used in animal experiments together with an American artificial lung for more than one month in the University of Texas and also in human trials in the Taiwan University. PMID:19662122

Qian, Kun-Xi

2007-06-28

429

Evaluation of Failed Crane Chempumps Used During Salt Well Pumping  

SciTech Connect

The Interim Stabilization Project is responsible for removing pumpable interstitial liquid from remaining single shelled tanks and transferring the waste to safer double-shelled tanks. This waste transfer is conducted by installing a saltwell pumping system within the designated single shell tank, and transferring the waste to double shelled tank using approved transfer lines. The saltwell pumping system is placed within a saltwell screen installed into the tank waste, the screen is designed to allow gravity flow of liquid into the screen and prevent solids from entering the pumping system. A foot valve consisting of a venturi jet and nozzle creates a suction, picking up waste at an equal rate as the out flow transfer rate of the saltwell system. A centrifugal pump is used to create the motive force across the eductor and drive the waste through the associated system piping and transfer lines leading to the double shelled tanks. The centrifugal pump that has typically been used in the saltwell pumping system installations is the Crane Chempump, model GA-1 1/2 K with 4 3/4 inch impeller. The following evaluation is not intended to be an all inclusive analysis of the operation of a saltwell system and associated pump. This evaluation will detail some of the noted failures in specific saltwell systems and document those findings. Due to the large number of saltwell systems installed over the duration of the Stabilization Project, only those saltwell systems installed over the last two years within S, SX, U, A and AX tank farms, shall be included in this evaluation. After identification of the pump failures mechanism, recommendations shall be identified to address potential means of improving overall operational efficiency and reducing overall equipment failures.

ELSEN, J.J.

2000-09-18

430

Laser (L2F) measurements at impeller inlet and tip exit of a 91 mm turbocharger compressor  

Microsoft Academic Search

Laser 2 Focus Velocimeter (L2F) measurements have been made at the impeller tip exit and at the inducer inlet of a 91 mm turbocharger compressor at various traverse depths and at different flow points. The data presented identifies splitter-to-blade and blade-to-splitter flow channel characteristics, at best efficiency and near surge. Additionally, the measurements at inducer inlet identify flow behavior at

M. Y. Young; W. A. Spraker; A. G. Struble

1987-01-01

431

Quantitative comparison of impeller-flowmeter and particle-size-distribution techniques for the characterization of hydraulic conductivity variability  

Microsoft Academic Search

Hydraulic conductivities associated with measurement scale of the order of 10–1 m and collected during an extensive field campaign near Tübingen, Germany, are analyzed. Estimates are provided at coinciding\\u000a locations in the system using: (1) the empirical Kozeny-Carman formulation, providing conductivity values, K\\u000a GS, based on particle-size distribution, and (2) borehole impeller-type flowmeter tests, which infer conductivity, K\\u000a FM, from measurements

Marco Barahona-Palomo; Monica Riva; Xavier Sanchez-Vila; Enric Vazquez-Sune; Alberto Guadagnini

2011-01-01

432

Analyses on the Performance and Interaction Between the Impeller and Casing in a Small-Size Turbo-Compressor  

NASA Astrophysics Data System (ADS)

The effects of casing shapes on the performance and the interaction between an impeller and a casing in a small-size turbo-compressor are investigated. Numerical analysis is conducted for the turbo-compressor with circular and single volute casings from the inlet to a discharge nozzle. The optimum design for each element is important to develop the small-size turbo-compressor using alternative refrigerant as a working fluid. Typically, the rotating speed of the compressor is in the range of 40000-45000rpm because of the small size of an impeller diameter. A blade of an impeller has backswept two-dimensional shape due to tip clearance and a vane diffuser has wedge type. In order to predict the flow pattern inside the entire impeller, the vaneless diffuser and the casing, calculations with multiple frames of reference method between the rotating and stationery parts of the domain are carried out. For compressible turbulent flow fields, the continuity and time-averaged three-dimensional Navier-Stokes equations are employed. To evaluate the performance of two types of casings, the static pressure recovery and loss coefficients are obtained with various flow rates. Also, static pressure distributions around casings are studied for different casing shapes, which are very important to predict the distribution of radial load. To prove the accuracy of numerical results, measurements of static pressure around the casing and pressure difference between the inlet and the outlet of the compressor are performed for the circular casing. The comparison of experimental and numerical results is conducted, and reasonable agreement is obtained.

Kim, Youn-Jea; Kim, Dong-Won

433

Temporal Evolution of the 3-D Flow Field In a Mixing Tank with a Two-Bladed Impeller  

NASA Astrophysics Data System (ADS)

The evolution of the 3-D flow field inside a cylindrical mixing vessel was measured using 3-D Cinematic Particle Tracking Velocimetry. The mixing vessel consisted of a cylindrical chamber with a two-bladed impeller axially centered in the vessel. The impeller was a simple paddle wheel-type and its height in the vessel could be externally adjusted. The fluid inside the chamber was seeded by small neutrally buoyant particles. The entire vessel volume was illuminated by a high-power, collimated strobe light located under the vessel and the particle motion was imaged by a pair of synchronized high-speed (up to 500 fps) digital cameras. Prior to the actual experiments, an in situ calibration of the cameras was performed to automatically account for the optical distortion resulting from the curved vessel boundaries and index of refraction mismatch. The long, high-speed video sequences were analyzed using the FloDyne(tm) 3-D Particle Tracking software. This typically resulted in 500-600 instantaneous 3-D velocity vectors over the entire vessel. The image sequences were then processed for a large number of impeller rotations (50, typically). The resulting velocity fields were then post-processed to obtain the evolution of the phase-averaged 3-D velocity field as well as estimates of the intrinsic turbulence intensities. Animation of the reconstructed 3-D flow fields will be shown. Under some geometrical configurations of the impeller at low Reynolds numbers, the results show the presence of quasi-stable recirculating regions inhibiting the overall mixing.

Choi, Woong-Chul; Guezennec, Yann G.

1998-11-01

434

The effect of surface roughness on activation of the coagulation system and platelet adhesion in rotary blood pumps.  

PubMed

The surface roughness of left ventricular assist devices (LVADs) is important for the biocompatibility of blood pumps. However, little is known about the effect of surface roughness on the antithrombogenicity of the device. The present study investigated the effect of surface roughness on the activation of the coagulation system and platelet adhesion in an impeller-type blood pump. Three identical Baylor Gyro 710 centrifugal blood pumps (Baylor College of Medicine, Houston, TX, USA) were manufactured with impeller surface roughness of 0.05, 0.2, and 0.4 microm, respectively, as determined by a stylus profilometer and by scanning electron microscopy. Whole blood was anticoagulated (1-IU heparin/mL, ACT 250 s) and circulated for 60 min in an artificial circulatory system, simulating LVAD perfusion (5-L/min flow against 100 mm Hg). Enzyme-linked immunosorbent assays were developed to quantify fibrinogen- and von Willebrand factor (vWf) adsorption as well as platelet adhesion directly on the impellers of the pumps. Levels of prothrombin fragment F1.2 and thrombin-antithrombin (TAT) complex were measured in order to quantify activation of coagulation. Compared with the 0.05-microm surface, platelet adhesion was 40 and 76% higher on the 0.2- and 0.4-microm surface, respectively (P < 0.01). The evaluation of adsorbed fibrinogen and vWf showed significant higher protein antigen levels on the rougher surfaces (P < 0.01). Furthermore, nonpulsatile perfusion activated the coagulation system. By contrast, the surface roughness had no significant influence on plasma prothrombin F1.2 fragment- and TAT concentrations. Antithrombogenicity was significantly reduced in pumps with inferior metal-finishing quality. PMID:17470203

Linneweber, Jörg; Dohmen, Pascal Maria; Kertzscher, Ulrich; Kerzscher, Ullrich; Affeld, Klaus; Nosé, Yukihiko; Konertz, Wolfgang

2007-05-01

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