These are representative sample records from Science.gov related to your search topic.
For comprehensive and current results, perform a real-time search at Science.gov.
1

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

2

CFD analysis of pump consortium impeller  

NASA Technical Reports Server (NTRS)

Current design of high performance turbopumps for rocket engines requires effective and robust analytical tools to provide design impact in a productive manner. The main goal of this study is to develop a robust and effective computational fluid dynamics (CFD) pump model for general turbopump design and analysis applications. A Navier-Stokes flow solver, FDNS, embedded with the extended k-epsilon turbulence model and with appropriate moving interface boundary conditions, is developed to analyze turbulent flows in the turbomachinery devices. The FDNS code was benchmarked with its numerical predictions of the pump consortium inducer, and provides satisfactory results. In the present study, a CFD analysis of the pump consortium impeller will be conducted with the application of the FDNS code. The pump consortium impeller, with partial blades, is the new design concept of the advanced rocket engine.

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

1992-01-01

3

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

4

Optimization and Inverse Design of Pump Impeller  

NASA Astrophysics Data System (ADS)

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

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

2012-11-01

5

Viscous flow prediction within a centrifugal impeller  

E-print Network

wish to thank Dr. M. P. Boyce for his guidance and assistance in the preparation of this thesis. I also wish to express my appreciation to Dr. T. J. Kozik and Dr. W. L. Perry for serving as members of my committee, and to Dr. C. M. Simmang... of the flow measured with respect to the rotating impeller is known as the relative velocity, W. As shown in Figure 3, the relative velocity may be broken into two components, W8 and Wm, The term W6 represents the projection of the relative velocity onto...

Wohlschlegel, David Hale

2012-06-07

6

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

NASA Astrophysics Data System (ADS)

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

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

2008-03-01

7

Recent progress in developing durable and permanent impeller pump.  

PubMed

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

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

2002-04-01

8

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

NASA Astrophysics Data System (ADS)

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

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

2010-06-01

9

Flow visualization study to investigate the secondary flow behind the impeller in the Gyro centrifugal pump.  

PubMed

The Gyro permanently implantable pump consists of a sealless pump housing and an impeller supported with a double pivot bearing. The secondary vanes are attached to increase the secondary flow to avoid thrombus formation behind the impeller. Flow visualization studies using an oil film method were performed on three types of impellers: no secondary vanes, 0.5 mm height secondary vanes, and 1.0 mm height secondary vanes. Comparison studies of these impellers were performed on the surfaces of the impeller bottom and bottom housing. Regarding the surface of the impeller bottom, the impeller with no secondary vanes had the least stagnant areas around the shaft. On the other hand, the impeller having 1.0 mm height secondary vanes had the most distinguished flow lines on the bottom housing. Overall, the impeller secondary vanes with a height of 0.5 mm (current design) seemed to create the most effective secondary flow. PMID:12460388

Ichikawa, Seiji; Nonaka, Kenji; Linneweber, Joerg; Kawahito, Shinji; Motomura, Minoru; Nishimura, Ikuya; Glueck, Julia; Shinohara, Toshiyuki; Nosé, Yukihiko

2002-12-01

10

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

NASA Technical Reports Server (NTRS)

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

Childs, D. W.

1991-01-01

11

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

12

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

PubMed

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

Ohara, Y; Takatani, S; Nosé, Y

1995-07-01

13

Arterial-venous perfusion without anticoagulation: the impeller centrifugal pump.  

PubMed

A study was designed to test the effects of the absence of anticoagulation in the extracorporeal circuit. Five swine were subjected to this experiment utilizing the impeller centrifugal pump during which neither heparin nor any other anticoagulant was used. The extracorporeal circuit consisted of polyvinylchloride tubing, a Centri-Med pump and an external stainless steel heat exchanger that was primed with albuminized Ringer's solution. An arterial-venous circuit was employed with oxygenation supplied from the subject's lungs. A series of blood aliquots were analyzed for coagulation at various times throughout the procedure. Following total body cooling using topically applied ice water, the subjects were rewarmed utilizing bypass. Within 10 minutes after the initiation of bypass, the circuits became clotted, rendering perfusion and subsequent warming ineffective. The lab values indicated that intrinsically activated coagulation occurred upon exposure to the extracorporeal apparatus. Flow visualization studies revealed a source of stagnant blood flow in the area around the hub of the pump head. Blood clot was similarly located in this area, with clot extension throughout the return circuit being realized. It is imperative that areas of stagnation be eliminated from extracorporeal circuits, since they may be potential sites for clot formation. PMID:10149016

Vertrees, R A; Yu, Y; Wacker, C; Cernaianu, A C; DelRossi, A J

1991-01-01

14

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

15

PUMP CAVITATION VARIOUS NPSHR CRITERIA, NPSHA MARGINS, AND IMPELLER LIFE EXPECTANCY  

Microsoft Academic Search

This part of the tutorial deals with pump cavitation, discussing various NPSHR criteria, NPSHA margins and impeller life expectancy. It gives an introduction to the subject mater and provides insights in particulars like cavitation inception, 3% head drop, and 40,000 hours impeller life, as well as NPSH scaling laws. It further devotes attention to the effect of dissolved gases and

Bruno Schiavello; Frank C. Visser

16

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

NASA Astrophysics Data System (ADS)

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

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

2012-06-01

17

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

SciTech Connect

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

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

1994-12-31

18

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

19

Force and moment rotordynamic coefficients for pump-impeller shroud surfaces  

NASA Technical Reports Server (NTRS)

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

Childs, Dara W.

1987-01-01

20

Internal hydraulic analysis of impeller rounding in centrifugal pumps as turbines  

SciTech Connect

The use of pumps as turbines in different applications has been gaining importance in the recent years, but the subject of hydraulic optimization still remains an open research problem. One of these optimization techniques that include rounding of the sharp edges at the impeller periphery (or turbine inlet) has shown tendencies of performance enhancement. In order to understand the effect of this hydraulic optimization, the paper introduces an analytical model in the pump as turbine control volume and brings out the functionalities of the internal variables classified under control variables consisting of the system loss coefficient and exit relative flow direction and under dependent variables consisting of net tangential flow velocity, net head and efficiency. The paper studies the effects of impeller rounding on a combination of radial flow and mixed flow pumps as turbines using experimental data. The impeller rounding is seen to have positive impact on the overall efficiency in different operating regions with an improvement in the range of 1-3%. The behaviour of the two control variables have been elaborately studied in which it is found that the system loss coefficient has reduced drastically due to rounding effects, while the extent of changes to the exit relative flow direction seems to be limited in comparison. The reasons for changes to these control variables have been physically interpreted and attributed to the behaviour of the wake zone at the turbine inlet and circulation within the impeller control volume. The larger picture of impeller rounding has been discussed in comparison with performance prediction models in pumps as turbines. The possible limitations of the analytical model as well as the test setup are also presented. The paper concludes that the impeller rounding technique is very important for performance optimization and recommends its application on all pump as turbine projects. It also recommends the standardization of the rounding effects over wide range of pump shapes including axial pumps. (author)

Singh, Punit; Nestmann, Franz [Institute of Water and River Basin Management (IWG), Karlsruhe Institute of Technology, Kaiser Str. 12, D 76131 Karlsruhe (Germany)

2011-01-15

21

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

NASA Technical Reports Server (NTRS)

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

Ryder, J. T.

1977-01-01

22

Experimental and theoretical investigations of the flow in radial impellers of centrifugal pumps at cavitation  

Microsoft Academic Search

The relationship between NPSH (Non Positive Suction Head) cavitation phenomena and energy transfer has been investigated by means of optical observation of the flow in radial impellers of centrifugal pumps. By using the model assumption that cavitation areas are limited by the isobaric line of vapor pressure it is possible to calculate the development of the cavitation area at decreasing

H.-J. Kleinert; G. Will; R. Finzel

1979-01-01

23

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

PubMed

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

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

2002-01-01

24

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

PubMed

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

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

2010-08-01

25

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

NASA Astrophysics Data System (ADS)

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

Misiewicz, Andrzej; Skrzypacz, Janusz

2011-06-01

26

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

27

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

NASA Technical Reports Server (NTRS)

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

Belgacem, Jery

1986-01-01

28

J-2X Fuel Pump Impeller Seal Simulations  

NASA Technical Reports Server (NTRS)

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

Schmauch, Preston B.; West, Jeffrey S.

2011-01-01

29

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

NASA Astrophysics Data System (ADS)

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

Zhu, Bing; Chen, Hongxun; Wei, Qun

2014-06-01

30

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

E-print Network

COMPRESSIBILITY EFFECTS ON ROTOR FORCES IN THE LEAKAGE PATH BETWEEN A SHROUDED PUMP IMPELLER AND ITS HOUSING A Thesis by NHAI THE CAO Submitted to the Office of Graduate Studies of Texas A8cM University in partial fulfilltnent... of the requirements for the degree of MASTER OF SCIENCE August 1993 Major Subject: Mechanical Engineering COMPRESSIBILITY EFFECTS ON ROTOR FORCES IN THE LEAKAGE PATH BETWEEN A SHROUDED PUMP IMPELLER AND ITS HOUSING A Thesis by NHAI THE CAO Approved...

Cao, Nhai The

2012-06-07

31

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

32

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

Microsoft Academic Search

Quasi-three-dimensional Navier-Stokes calculations were carried out for the Space Shuttle Main Engine high-pressure fuel pump to simulate the impeller shroud to casing leakage flow. This flow geometry was modeled as an axisymmetric cavity flow with a stationary surface representing the casing, and a rotating surface denoting the impeller. A 63 x 81-node mesh provided sufficient resolution in the regions of

Munir M. Sindir

1987-01-01

33

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

NASA Technical Reports Server (NTRS)

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

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

1990-01-01

34

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

35

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

PubMed

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

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

2006-01-01

36

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

37

Effect of vortical structures on cavitation on impeller blades in pumps with suction chambers  

NASA Astrophysics Data System (ADS)

A double-suction pump operating at relatively low suction head and with poorly designed suction chambers was analysed by the computational fluid dynamics (CFD). Two impeller geometries were considered - one with thicker and one with thin layer of predicted vapour cavity on blades. Steady-state simulations (SSS) were performed with shear-stress- transport (SST) turbulence model with curvature correction (CC). Transient simulations were performed with scale-adaptive-simulation SST (SAS-SST) model with CC. For both analysed geometries, transient simulations predicted higher maximal thickness of cavities than SSS. In transient simulations it was observed that, because of poor design of suction chambers, near the rib of the suction chambers two stronger (non-cavitating) vortices appeared. Near the main vortical structures, vortices with smaller intensity appeared, with direction of rotation opposite to the main vortices. Depending on their position and direction of rotation, the vortices either decreased or increased the extent of cavitation. The most important adverse effect was to increase the size of the sheet cavity by local elongation and thickening. The local effect seemed to be more pronounced for impeller with smaller thickness of sheet cavity.

Škerlavaj, A.; Pavlin, R.

2014-12-01

38

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

39

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

PubMed

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

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

2009-10-01

40

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

NASA Astrophysics Data System (ADS)

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

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

2013-02-01

41

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

E-print Network

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

Park, Sang

2010-01-16

42

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

E-print Network

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

Kenis, Paul J. A.

43

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

SciTech Connect

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

Hamrick, J.T.

1980-04-01

44

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

Microsoft Academic Search

Cavitation is well-known phenomenon which occurs in the pump and may lead to the pump damage. Thus it is very important to\\u000a predict cavitation parameters, during the design of the pomp elements. There are a lot of methods to estimate cavitation factor\\u000a of the pump, but these methods are true only for elements designed in the “standard way” consisted algorithms,

Andrzej Misiewicz; Janusz Skrzypacz

2011-01-01

45

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

NASA Technical Reports Server (NTRS)

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

Pool, Kirby V.

1989-01-01

46

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

NASA Technical Reports Server (NTRS)

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

Baskharone, Erian A.

1993-01-01

47

Waterjet Impeller  

NASA Technical Reports Server (NTRS)

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

1996-01-01

48

Unshrouded Impeller Technology Development Status  

NASA Technical Reports Server (NTRS)

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

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

2000-01-01

49

Waterjet Impeller  

NASA Technical Reports Server (NTRS)

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

1996-01-01

50

Design of a high-pressure circulating pump for viscous liquids  

NASA Astrophysics Data System (ADS)

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

Seifried, Bernhard; Temelli, Feral

2009-07-01

51

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

NASA Technical Reports Server (NTRS)

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

Kiris, Cetin

1992-01-01

52

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

NASA Technical Reports Server (NTRS)

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

Ohashi, Hideo; Sakurai, Akira; Nishihama, Jiro

1989-01-01

53

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

54

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

NASA Technical Reports Server (NTRS)

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

Russell, John M.

2002-01-01

55

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

56

INVESTIGATION OF CAVITATION DAMAGE OF MECHANICAL PUMP IMPELLERS OPERATING IN LIQUID METAL SPACE POWER LOOPS. Quarterly Progress Report No. 2, October 1, 1963December 31, 1963  

Microsoft Academic Search

Water testing of the RI-7C3 impeller in the Pt-2 test stand was ;\\u000a completed. Still photographs and movies showed that a vortex was present on the ;\\u000a leading edge tip of all blades at NPSH values up to 150 ft at all five test flows ;\\u000a of 660, 680, 700, 720, and 740 gpm. Sound data showed a possible correlation

R. S. Kulp; J. V. Altieri

1964-01-01

57

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

PubMed Central

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

Qian, Kun-xi

2007-01-01

58

Aerodynamic Synthesis of a Centrifugal Impeller Using CFD and Measurements  

NASA Technical Reports Server (NTRS)

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

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

1997-01-01

59

Liquid Scavenger for Separator/Pump  

NASA Technical Reports Server (NTRS)

Pump for hydrogen modified to remove moisture that condenses in impeller stage. Impeller-pump housing has circumferential groove leading to exit hole near high-pressure outlet. As impeller disk rotates, flings water droplets condensed in pump toward groove. Aerodynamic drag drives water around groove to exit hole.

Berg, P. F.

1986-01-01

60

Floating portable pump  

SciTech Connect

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

Eberhardt, H. A.

1985-11-19

61

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

62

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

NASA Astrophysics Data System (ADS)

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

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

2013-12-01

63

Axial Pump  

NASA Technical Reports Server (NTRS)

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

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

1997-01-01

64

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

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

1993-07-01

65

Mathematical modeling of fluid flow in aluminum ladles for degasification with impeller - injector  

NASA Astrophysics Data System (ADS)

In this work a fundamental Eulerian mathematical model was developed to simulate fluid flow in a water physical model of an aluminum ladle equipped with impeller for degassing treatment. The effect of critical process parameters such as rotor speed, gas flow rate on the fluid flow and vortex formation was analyzed with this model. Commercial CFD code PHOENICS 3.4 was used to solve all conservation equations governing the process for this twophase fluid flow system. The mathematical model was successfully validated against experimentally measured liquid velocity and turbulent profiles in a physical model. From the results it was concluded that the angular speed of the impeller is the most important parameter promoting better stirred baths. Pumping effect of the impeller is increased as impeller rotation speed increases. Gas flow rate is detrimental on bath stirring and diminishes pumping effect of impeller.

Ramos-Gómez, E.; González-Rivera, C.; Ramírez-Argáez, M. A.

2012-09-01

66

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

NASA Technical Reports Server (NTRS)

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

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

1953-01-01

67

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

PubMed Central

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

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

2008-01-01

68

Osmotic stress and viscous retardation of the Na,K-ATPase ion pump.  

PubMed

The transport function of the Na pump (Na,K-ATPase) in cellular ion homeostasis involves both nucleotide binding reactions in the cytoplasm and alternating aqueous exposure of inward- and outward-facing ion binding sites. An osmotically active, nonpenetrating polymer (poly(ethyleneglycol); PEG) and a modifier of the aqueous viscosity (glycerol) were used to probe the overall and partial enzymatic reactions of membranous Na,K-ATPase from shark salt glands. Both inhibit the steady-state Na,K-ATPase as well as Na-ATPase activity, whereas the K(+)-dependent phosphatase activity is little affected by up to 50% of either. Both Na,K-ATPase and Na-ATPase activities are inversely proportional to the viscosity of glycerol solutions in which the membranes are suspended, in accordance with Kramers' theory for strong coupling of fluctuations at the active site to solvent mobility in the aqueous environment. PEG decreases the affinity for Tl(+) (a congener for K(+)), whereas glycerol increases that for the nucleotides ATP and ADP in the presence of NaCl but has little effect on the affinity for Tl(+). From the dependence on osmotic stress induced by PEG, the aqueous activation volume for the Na,K-ATPase reaction is estimated to be approximately 5-6 nm(3) (i.e., approximately 180 water molecules), approximately half this for Na-ATPase, and essentially zero for p-nitrophenol phosphatase. The change in aqueous hydrated volume associated with the binding of Tl(+) is in the region of 9 nm(3). Analysis of 15 crystal structures of the homologous Ca-ATPase reveals an increase in PEG-inaccessible water space of approximately 22 nm(3) between the E(1)-nucleotide bound forms and the E(2)-thapsigargin forms, showing that the experimental activation volumes for Na,K-ATPase are of a magnitude comparable to the overall change in hydration between the major E(1) and E(2) conformations of the Ca-ATPase. PMID:18055532

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

2008-04-01

69

Rotordynamic characteristics of a shrouded pump impeller  

E-print Network

Rotordynamic Forces Predicted With A Three ? Dimensional Navier ? Stokes Computer ? Code, " in Zenith AIAA Joint Propulsion Conference and Ezhibit, Boston, 1988. Dietzen, F. J. and Nordmann, R. , "A 3 ? Dimensional Finite ? Difference Method for Calculating... in the vector fiIi), repeated as many times as the number of tangential planes around the circumference in the three ? dimensional finite element model may be. Next, a transition step is performed whereby the nodal velocity components V?V?and Vs are adjusted...

Abou-El-Kheir, Magdy Sobhy

1991-01-01

70

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

NASA Astrophysics Data System (ADS)

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

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

2015-01-01

71

Rotary blood pump  

NASA Technical Reports Server (NTRS)

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

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

1993-01-01

72

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

NASA Technical Reports Server (NTRS)

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

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

1993-01-01

73

[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

74

Rotary Blood Pump  

NASA Technical Reports Server (NTRS)

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

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

1996-01-01

75

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

NASA Technical Reports Server (NTRS)

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

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

1972-01-01

76

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

NASA Technical Reports Server (NTRS)

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

Childs, D. W.

1992-01-01

77

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

E-print Network

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

Tarr, David Landon

2008-01-01

78

Flow in a centrifugal fan impeller at off-design conditions  

NASA Astrophysics Data System (ADS)

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

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

1984-06-01

79

An evaluation of subsea pump technologies that can be used to achieve dual gradient drilling  

E-print Network

to their smaller size. They include Multi-Stage Electrical Submersible pumps, Centrifugal pumps, Disc pumps and Helico-axial (Poseidon) pumps. Figure 3.1 shows a general pump classification. 27 Fig. 3.1?General Pump Classification... pumps may have single or double volute passages. The Prime-Mover is usually an electric motor, hence the name electrical submersible pump (ESP). It provides torque needed to drive the shaft and impeller. As the impeller rotates and the fluid...

Oluwadairo, Tolulope

2009-05-15

80

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

PubMed Central

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

2013-01-01

81

SSME HPOTP impeller backcavity CFD analysis  

NASA Technical Reports Server (NTRS)

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

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

1992-01-01

82

Vibration analysis of large centrifugal pump rotors  

NASA Astrophysics Data System (ADS)

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

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

2013-12-01

83

Variable Frequency Pump Drives  

E-print Network

detail. Compounding energy wastage, flow control by throttling may force the pump to operate in a region of its performance curve which reduces impeller, clearance, shaft seal and bearing life. Fig. 3 shows, in a qualitative way, how pump wear..., hence life, can vary with flow. RATE OF WEAR DEPENDS UPON: ? % BEP ? ENERGY LEVEL RATE OF PUMP WEAR BEP FLOW FIGURE 3 Finally, the need to throttle with the control valve adds extra hardware to the line, and contributes to wear...

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

84

Liquid rocket propulsion impeller CFD modeling  

Microsoft Academic Search

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

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

1993-01-01

85

Pump CFD code validation tests  

NASA Technical Reports Server (NTRS)

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

Brozowski, L. A.

1993-01-01

86

Flow Pattern Characterization for a Centrifugal Impeller  

NASA Astrophysics Data System (ADS)

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

Benavides, Efrén M.

2014-08-01

87

Design and Test of Mixed-flow Impellers IV : Experimental Results for Impeller Models MFI-1 and MFI-2 with Changes in Blade Height  

NASA Technical Reports Server (NTRS)

Modifications A and B of impeller model MFI-1 and A, B, and C of impeller model MFI-2 were investigated experimentally in an attempt to determine what allowance in blade height should be made for boundary layer and viscous losses in an impeller designed for isentropic compressible flow. A gradual increase in blade height was arbitrarily made from inlet to outlet in anticipation of a gradual build-up of boundary layer. Apparently there was a rapid build-up of boundary layer near the inlet in the experimental case rather than a gradual one. Therefore, the proper allowance for boundary layer cannot be described from the data obtained. Decreasing the pressure gradient along the shroud by reducing the blade height allowance apparently did little to increase the overall efficiency. At the design speed of 1400 feet per second, the overall adiabatic efficiency was increased from 0.83 for the MFI-1A to 0.85 for the MFI-1B with reduction in height; however, it is indicated from the theoretical velocity distribution and outlet surveys that the increase was due to a change from decelerating to accelerating flow along the hub rather than from any change along the shroud. It is further indicated that the consequences of a thickened or separated boundary layer depend not only on the design velocity gradients but also on the shape of the passage.

Hamrick, Joseph T; Beede, William L; Withee, Joseph R JR

1954-01-01

88

CFD simulation of the laminar flow in stirred tanks generated by double helical ribbons and double helical screw ribbons impellers  

Microsoft Academic Search

In this paper, the mixing performance of double helical ribbons and double helical screw ribbons impellers mounted on stirred\\u000a tanks is numerical investigated. The computer simulations are conducted within a specific computational fluid dynamic (CFD)\\u000a code, based on resolution of the Naviers-Stokes equations in the laminar flow with a finite volume discretization. The field\\u000a velocity and the viscous dissipation rate

Zied Driss; Sarhan Karray; Hedi Kchaou; Mohamed Salah Abid

2011-01-01

89

Design and Test of Mixed-flow Impellers II : Experimental Results, Impeller Model MFI-1A  

NASA Technical Reports Server (NTRS)

An investigation was conducted to determine the performance characteristics of a mixed-flow impeller which was designed with special emphasis on the reduction or elimination of flow decelerations along wetted surfaces. The performance was investigated over a range of equivalent impeller speeds from 700 to 1600 feet per second and over a range of flow rates from maximum adiabatic temperature-rise efficiency, measured at 1-1/2 impeller diameters in a vaneless diffuser, at the design speed of 1400 feet per second were 4.00 and 0.83, respectively.

Withee, Joseph R , Jr; Beede, William L

1952-01-01

90

Study of blade clearance effects on centrifugal pumps  

NASA Technical Reports Server (NTRS)

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

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

1972-01-01

91

An Integrated Machining Approach for a Centrifugal Impeller  

Microsoft Academic Search

When a 3-axis CNC machining centre is used for producing an impeller, great difficulties, i.e. collisions between the cutting tool and the impeller, can occur. The blade of an impeller is usually designed with a ruled surface. As the surface is normally twisted in design to achieve the required performance, it can cause overcut and collision problems during machining. The

H.-T. Young; L.-C. Chuang

2003-01-01

92

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

PubMed

The new miniature axial flow pump (valvo pump 2) that is installed at the base of the ascending aorta consists of a six-phase stator, an impeller in which four neodymium magnets are incorporated, and passive magnetic bearings that suspend the impeller for axial levitation. The impeller is sustained by hydrodynamic force between the blade tip of the impeller and the inner housing of the stator. The passive magnetic bearing consists of a ring neodymium magnet and a columnar neodymium magnet. The ring neodymium magnet is set in the stationary side and the columnar neodymium magnet is incorporated in the impeller shaft. Both neodymium magnets are coaxially mounted, and the anterior and posterior passive magnetic bearings suspend the impeller by repulsion force against the hydrodynamic force that acts to move the impeller in the inflow port direction. The passive magnetic bearing was evaluated by a tensile test, and the levitation force of 8.5 N and stiffness of 2.45 N/mm was obtained. Performance of the axial flow pump was evaluated by an in vitro experiment. The passive magnetic bearing showed sufficient levitation capacity to suspend the impeller in an axial direction. In conclusion, the passive magnetic bearing is promising to be one of levitation technology for the third-generation axial flow blood pump. PMID:25407124

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

2014-11-19

93

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

94

Method for Reducing Pumping Damage to Blood  

NASA Technical Reports Server (NTRS)

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

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

1997-01-01

95

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

PubMed

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

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

2014-01-01

96

Optimization and Analysis of Centrifugal Pump considering Fluid-Structure Interaction  

PubMed Central

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

Hu, Sanbao

2014-01-01

97

Liquid rocket propulsion impeller CFD modeling  

NASA Astrophysics Data System (ADS)

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

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

1993-06-01

98

Liquid rocket propulsion impeller CFD modeling  

NASA Technical Reports Server (NTRS)

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

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

1993-01-01

99

Engineering Aspects in Blood Pump Development  

NASA Technical Reports Server (NTRS)

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

Golding, Leonard; Veres, Joseph P.

1997-01-01

100

Preventing cavitation in high energy centrifugal pumps  

Microsoft Academic Search

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

A. W. F. Garbers; A. K. Wasfi

1990-01-01

101

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

102

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

103

Experimental observation of the flow in impellers and diffusers  

Microsoft Academic Search

Conventional and optical measurements were carried out within centrifugal compressor impellers and diffusers. A highly distorted impeller discharge flow, pointing to a mass flow concentration in the hub area and a wake flow close to the shroud, is indicated by the conventional measurements. This flow character causes a highly nonuniform flow incidence angle distribution at the diffuser vane leading edge

H. Krain

1984-01-01

104

Optimization of Integrated Impeller Mixer via Radiotracer Experiments  

PubMed Central

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

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

2014-01-01

105

Optimization of integrated impeller mixer via radiotracer experiments.  

PubMed

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

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

2014-01-01

106

Viscous Fluids  

NSDL National Science Digital Library

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

Integrated Teaching And Learning Program

107

Satellite Propellant Pump Research  

NASA Technical Reports Server (NTRS)

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

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

2005-01-01

108

Detection and effects of pump low-flow operation  

SciTech Connect

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

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

1993-12-01

109

Controlling granule size through breakage in a novel reverse-phase wet granulation process; the effect of impeller speed and binder liquid viscosity.  

PubMed

The feasibility of a novel reverse-phase wet granulation process has been established previously highlighting several potential advantages over the conventional wet granulation process and making recommendations for further development of the approach. The feasibility study showed that in the reverse-phase process granule formation proceeds via a controlled breakage mechanism. Consequently, the aim of the present study was to investigate the effect of impeller speeds and binder liquid viscosity on the size distribution and intragranular porosity of granules using this novel process. Impeller tip speed was found to have different effects on the granules produced by a conventional as opposed to a reverse-phase granulation process. For the conventional process, an increase in impeller speed from 1.57 to 3.14ms(-1) had minimal effect on granule size distribution. However, a further increase in impeller tip speed to 3.93 and 4.71ms(-1) resulted in a decrease in intragranular porosity and a corresponding increase in mean granule size. In contrast when the reverse-phase process was used, an increase in impeller speed from 1.57 to 4.71ms(-1) resulted in increased granule breakage and a decrease in the mean granule size. This was postulated to be due to the fact that the granulation process begins with fully saturated pores. Under these conditions further consolidation of granules at increased impeller tip speeds is limited and rebound or breakage occurs. Based on these results and analysis of the modified capillary number the conventional process appears to be driven by viscous forces whereas the reverse-phase process appears to be driven by capillary forces. Additionally, in the reverse-phase process a critical impeller speed, represented by the equilibrium between centrifugal and gravitational forces, appears to represent the point above which breakage of large wet agglomerates and mechanical dispersion of binder liquid take place. In contrast the conventional process appears to be difficult to control due to variations in granule consolidation, which depends upon experimental variables. Such variations meant increased impeller tip speed both decreased and increased granule size. The reverse-phase process appears to offer simple control over granule porosity and size through manipulation of the impeller speed and further evaluation of the approach is warranted. PMID:25475017

Wade, J B; Martin, G P; Long, D F

2015-01-30

110

Research on wear properties of centrifugal dredge pump based on liquid-solid two-phase fluid simulations  

NASA Astrophysics Data System (ADS)

The impeller and casing of dredge pump are worn by sediment in the flow. However, there are few studies about abrasion of the impeller and casing for normal pump operating conditions. This paper investigated the relationship between the wear rates on the surfaces of the impeller as well as casing and the sediment concentration, with the distribution of the wear rates for normal pump operating condition analyzed. An Eulerian-Lagrangian Computational Fluid Dynamics (CFD) procedure was used to simulate steady liquid-solid two-phase flow for various operating conditions. The Finnie model was then used to predict the abrasion. The results show that, the wear rate relative value of impeller and casing surface increase as the sediment concentration increases. The wear rate relative value of impeller and casing surface is larger when the pump is in low flow rate condition, and the value of casing surface is larger than that of the impeller. The wear rate relative value of pump is low when pump is in high efficiency condition. This paper shows the abrasion characteristics on the impeller and casing with sediment flow and provides reference data for predicting the abrasion conditions in the flow passage components for a dredge pump.

Peng, G. J.; Luo, Y. Y.; Wang, Z. W.

2015-01-01

111

Research on 3-D discharge flow in a centrifugal impeller  

NASA Astrophysics Data System (ADS)

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

Xi, Guang; Wang, Shangjin

1993-01-01

112

Novel maglev pump with a combined magnetic bearing.  

PubMed

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

Onuma, Hiroyuki; Murakami, Michiko; Masuzawa, Toru

2005-01-01

113

Laser velocimetry study of the flow field in a centrifugal pump  

E-print Network

The flow field in the impeller passages in a centrifugal pump was measured using a two dimensional laser 2-focus velocimeter. Measurements were taken at three circumferential (azimuthal) locations at the design and off-design operating conditions...

Rashid, Kazi M.

2012-06-07

114

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

115

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

116

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

117

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

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

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

118

How to adjust vertical turbine pumps for maximum efficiency  

SciTech Connect

The average performance indicates that about 30% of the energy used for irrigation could be saved if all pumping plants operated at the Nebraska Performance Criteria. There are many causes for poor pumping plant performance. Major causes were poor power unit performance, and poor pump performance often caused by improper pump adjustment. This circular discusses proper pump adjustment to attain maximum efficiency. Both semi-open and enclosed types of turbine pumps used in irrigation can benefit from proper impeller adjustment provided enough wear has occurred to allow water to leak past the pump seals and be recirculated within the pump bowl, and that there is enough seal area remaining in the bowl to reestablish a seal by lowering the impellers.

Dorn, T.W.; Schroeder, M.A.; Fischbach, P.E.

1986-01-01

119

Impeller Metrology for Pipeline Compressors Using Computed Radiography  

SciTech Connect

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

Nelson, G.; Gordon, T.; Bueno, C.; Noonan, D. [GE Global Research, Niskayuna, NY 12302 (United States); George, S.; Mahesh, A.; Korukonda, S. [DepartmentGE Global Research, Bangalore, 560066 (India); Fabbri, M.; Cantelli, U.; Marcucci, N. [GE Oil and Gas, Florence 50127 (Italy)

2006-03-06

120

Research on 3-D discharge flow in a centrifugal impeller  

Microsoft Academic Search

A method for calculating 3D discharge flow in a centrifugal impeller is developed by means of solving the incompressible steady time-averaged N-S equations, the continuity equation, and the k-epsilon turbulence model equation. This method is accomplished with calculation grids generated by an algebraic transformation, and thus it can be easily applied to the design analysis of centrifugal impellers. The discharge

Guang Xi; Shangjin Wang

1993-01-01

121

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

122

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

NASA Astrophysics Data System (ADS)

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

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

2015-01-01

123

Design of a Bearingless Blood Pump  

NASA Technical Reports Server (NTRS)

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

Barletta, Natale; Schoeb, Reto

1996-01-01

124

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

125

Fluid pumping apparatus  

DOEpatents

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

West, Phillip B. (Idaho Falls, ID)

2006-01-17

126

SSME HPOTP impeller backcavity CFD analysis  

Microsoft Academic Search

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

W. W. Hsu; S. J. Lin

1992-01-01

127

Taking Another Look at Pumping Systems: Opportunities Go Well Beyond Just Energy Savings  

E-print Network

of pumping system behavior critical to ensuring proper pumping system operation including: o NPSH adequacy o Pump efficiency and Best Efficiency Point (BEP) identification o Modified pump performance due to impeller trimming o Variable frequency drives...Taking Another Look at Pumping Systems: Opportunities Go Well Beyond Just Energy Savings Vestal Tutterow, P.E. Senior Program Manager Alliance to Save Energy Washington, DC Trey Walters, P.E. President Applied Flow Technology Woodland...

Tutterow, V.; Walters, T.

2006-01-01

128

The effect of gas fraction on centrifugal pump  

NASA Astrophysics Data System (ADS)

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

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

2015-01-01

129

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

PubMed Central

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

Hu, Jinfei; Tse, Peter W.

2013-01-01

130

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

PubMed

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

Hu, Jinfei; Tse, Peter W

2013-01-01

131

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

NASA Technical Reports Server (NTRS)

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

Tatchell, D. G.

1979-01-01

132

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

133

Analysis of novel low specific speed pump designs  

NASA Astrophysics Data System (ADS)

Centrifugal pumps with very low specific speed present significant design challenges. Narrow blade channels, large surface area of hub and shroud discs relative to the blade area, and the presence of significant of blade channel vortices are typical features linked with the difficulty to achieve head and efficiency requirements for such designs. This paper presents an investigation of two novel designs of very low specific speed impellers: impeller having blades with very thick trailing edges and impeller with thick trailing edges and recirculating channels, which are bored along the impeller circumference. Numerical simulations and experimental measurements were used to study the flow dynamics of those new designs. It was shown that thick trailing edges suppress local eddies in the blade channels and decrease energy dissipation due to excessive swirling. Furthermore the recirculating channels will increase the circumferential velocity component on impeller outlet thus increasing the specific energy, albeit adversely affecting the hydraulic efficiency. Analysis of the energy dissipation in the volute showed that the number of the recirculating channels, their geometry and location, all have significant impact on the magnitude of dissipated energy and its distribution which in turn influences the shape of the head curve and the stability of the pump operation. Energy dissipation within whole pump interior (blade channels, volute, rotor- stator gaps) was also studied.

Klas, R.; Pochylý, F.; Rudolf, P.

2014-12-01

134

Trailing edge noise reduction in a backward-curved impeller  

Microsoft Academic Search

Motorized impellers are used in many air-moving applications including room circulation, duct flow, roof and wall exhaust, and cooling of electronic components in cabinets. These fans are backward-curved centrifugal blowers that operate with no volute casing. These fans radiate broadband noise due to turbulence ingestion and trailing edge (TE) noise generating mechanisms. Considered here are trailing edge noise generation and

Gerald C. Lauchle

2002-01-01

135

SSME Investment in Turbomachinery Inducer Impeller Design Tools and Methodology  

NASA Technical Reports Server (NTRS)

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

Zoladz, Thomas; Mitchell, William; Lunde, Kevin

2010-01-01

136

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

PubMed

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

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

2006-05-01

137

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

PubMed

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

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

2009-01-01

138

Experimental and numerical study of three-dimensional flows in a mixed-flow pump stage  

Microsoft Academic Search

Internal flows of a low-specific-speed pump stage, having a mixed-flow impeller and a vaned bowl diffuser combination, have been investigated experimentally and numerically. Air was used as the test fluid, and the internal flows were measured at various locations and under various capacities. Flow calculations were made, for both the isolated impeller case and the complete stage case, using Denton

T. Takemura; A. Goto

1996-01-01

139

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

NASA Astrophysics Data System (ADS)

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

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

2015-01-01

140

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

141

Canned pump having a high inertia flywheel  

DOEpatents

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

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

1989-01-01

142

[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

143

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

144

Parametric performance evaluation of a hydraulic centrifugal pump  

NASA Astrophysics Data System (ADS)

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

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

2014-12-01

145

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

NASA Astrophysics Data System (ADS)

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

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

2013-12-01

146

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

147

Viscous Buckle Folding  

NSDL National Science Digital Library

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

Resor, Phil

148

Viscous fluid sheets  

E-print Network

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

Savva, Nikos

2007-01-01

149

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

NASA Astrophysics Data System (ADS)

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

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

2013-12-01

150

Design key to fluid flow, pump maintenance  

SciTech Connect

This article discusses some of the possible problems caused by improperly designed piping and presents guidelines for avoiding or at least reducing them. Explains that even if design and manufacture are precisely correct and the pump perfectly matched to the operating conditions, the pump can perform properly only if supplied with a steady flow of liquid arriving at the pump suction flange under sufficient absolute pressure to equal or exceed the net positive suction head (npsh) required by the pump and with uniform velocity with no rotational component. Points out that failure of the suction piping to deliver the liquid to the pump in this condition can lead to noisy operation, random axial oscillations of the rotor, premature bearing failure, and cavitation damage to the impeller and inlet portions of the casing. Discusses adequate priming or venting, piping velocities, and elbow use limits.

Krutzsch, W.C.

1983-01-24

151

Integrable viscous conservation laws  

E-print Network

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

Alessandro Arsie; Paolo Lorenzoni; Antonio Moro

2014-06-25

152

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

153

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

NASA Technical Reports Server (NTRS)

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

1991-01-01

154

Numerical study of cavitation flows inside a tubular pumping station  

NASA Astrophysics Data System (ADS)

Based on RNG k-epsilon turbulence model and the full cavitation model, the cavitation flows inside a low-head tubular-pump model were predicted by using the FLUENT software. For a operating case of given flow rate, cavitation happens near the inlet on the suction surfaces of the impeller blades at the initial cavitating stage, and the cavitating area spreads to the impeller passage and hub as NPSH (net positive suction head) decreases, which will affect energy transformation. For various operating cases of cavitation flows at the given flow rates, the predicted velocity and pressure distributions as well as the vapor volumetric fraction are systematically analyzed. Finally, the cavitation performance curve of the tubular-pump model is obtained by means of the further post-processing. All the comparisons and analysis can be further employed to optimize the hydraulic and structural design of the tubular pump and to guide its safe operation.

Tang, X. L.; Huang, W.; Wang, F. J.; Yang, W.; Wu, Y. L.

2012-11-01

155

Influence of impeller shroud forces on turbopump rotor dynamics  

NASA Technical Reports Server (NTRS)

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

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

1993-01-01

156

Effect of area ratio on the performance of a 5.5:1 pressure ratio centrifugal impeller  

NASA Technical Reports Server (NTRS)

A centrifugal impeller which was initially designed for a pressure ratio of approximately 5.5 and a mass flow rate of 0.959 kg/sec was tested with a vaneless diffuser for a range of design point impeller area ratios from 2.322 to 2.945. The impeller area ratio was changed by successively cutting back the impeller exit axial width from an initial value of 7.57 mm to a final value of 5.97 mm. In all, four separate area ratios were tested. For each area ratio a series of impeller exit axial clearances was also tested. Test results are based on impeller exit surveys of total pressure, total temperature, and flow angle at a radius 1.115 times the impeller exit radius. Results of the tests at design speed, peak efficiency, and an exit tip clearance of 8 percent of exit blade height show that the impeller equivalent pressure recovery coefficient peaked at a design point area ratio of approximately 2.748 while the impeller aerodynamic efficiency peaked at a lower value of area ratio of approximately 2.55. The variation of impeller efficiency with clearance showed expected trends with a loss of approximately 0.4 points in impeller efficiency for each percent increase in exit axial tip clearance for all impellers tested.

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

1986-01-01

157

Assessment of standard k – ? , RSM and LES turbulence models in a baffled stirred vessel agitated by various impeller designs  

Microsoft Academic Search

In the present work, laser-doppler anemometry measurements as well as CFD simulations have been performed for the flow generated by various impellers, namely disc turbine (DT), a variety of pitched blade down flow turbine impellers varying in blade angle (Standard PBTD60, 45 and 30) and hydrofoil (HF) impeller. The tank was fully baffled, and the flow regime was turbulent. The

B. N. Murthy; J. B. Joshi

2008-01-01

158

Effect of impeller design and spacing on gas exchange in a percutaneous respiratory assist catheter.  

PubMed

Providing partial respiratory assistance by removing carbon dioxide (CO2 ) can improve clinical outcomes in patients suffering from acute exacerbations of chronic obstructive pulmonary disease and acute respiratory distress syndrome. An intravenous respiratory assist device with a small (25 Fr) insertion diameter eliminates the complexity and potential complications associated with external blood circuitry and can be inserted by nonspecialized surgeons. The impeller percutaneous respiratory assist catheter (IPRAC) is a highly efficient CO2 removal device for percutaneous insertion to the vena cava via the right jugular or right femoral vein that utilizes an array of impellers rotating within a hollow-fiber membrane bundle to enhance gas exchange. The objective of this study was to evaluate the effects of new impeller designs and impeller spacing on gas exchange in the IPRAC using computational fluid dynamics (CFD) and in vitro deionized water gas exchange testing. A CFD gas exchange and flow model was developed to guide a progressive impeller design process. Six impeller blade geometries were designed and tested in vitro in an IPRAC device with 2- or 10-mm axial spacing and varying numbers of blades (2-5). The maximum CO2 removal efficiency (exchange per unit surface area) achieved was 573 ± 8 mL/min/m(2) (40.1 mL/min absolute). The gas exchange rate was found to be largely independent of blade design and number of blades for the impellers tested but increased significantly (5-10%) with reduced axial spacing allowing for additional shaft impellers (23 vs. 14). CFD gas exchange predictions were within 2-13% of experimental values and accurately predicted the relative improvement with impellers at 2- versus 10-mm axial spacing. The ability of CFD simulation to accurately forecast the effects of influential design parameters suggests it can be used to identify impeller traits that profoundly affect facilitated gas exchange. PMID:24749994

Jeffries, R Garrett; Frankowski, Brian J; Burgreen, Greg W; Federspiel, William J

2014-12-01

159

An experimental study on pump clogging  

NASA Astrophysics Data System (ADS)

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

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

2014-12-01

160

Blood Pump Bearing System  

NASA Technical Reports Server (NTRS)

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

Aber, Gregory S. (Inventor)

2000-01-01

161

Blood Pump Bearing System  

NASA Technical Reports Server (NTRS)

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

Aber, Gregory S. (Inventor)

1999-01-01

162

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

NASA Technical Reports Server (NTRS)

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

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

1992-01-01

163

Physiologic analysis of cardiac cycle in an implantable impeller centrifugal left ventricular assist device.  

PubMed

The purpose of this study was to determine the physiologic relationship between the cardiac cycle and the nonpulsatile impeller centrifugal Taita No.1 left ventricular assist device (T-LVAD) in a chronic animal study. The relationship of the cardiac cycle, pump flow, aortic pressure, left ventricle pressure, and pump power were analyzed by 5 phases in 4 stages. The isovolumetric ventricular phase is from mitral valve closure (MVC) to aortic valve opening (AVO) and is called Stage 1. The ejection phase is from AVO to aortic valve closure (AVC) and is called Stage 2. The isovolumetric relaxation phase is from AVC to MVC and is called Stage 3. The passive filling and atrial contraction phase is from MVC to mitral valve opening (MVO) and called Stage 4. Based on evidence from the physiologic volume change of the left ventricle, the change of pump flow of the T-LVAD in a cardiac cycle by variable voltages of pump control was evaluated using animal models. After left posteriolateral thoracotomy via the fifth intercostal space under general anesthesia, the nonpulsatile centrifugal T-LVAD was implanted into 2 healthy calves. The inflow of the T-LVAD was inserted into the left ventricle through the mitral valve via the left atrial appendage. The arterial blood pressure waveform was measured and recorded on the outflow of the T-LVAD. The 4 phases of a cardiac cycle were defined as MVC-AVO (Stage 1), AVO-AVC (Stage 2), AVC-MVO (Stage 3) and MVC-MVO (Stage 4) according to the outflow pressure of the outflow of the T-LVAD and differential pressure between the outflow and inflow of the T-LVAD. We carried out the real-time waveform measurement for electrocardiogram, the outflow pressure, the T-LVAD flow and the speed, as well as open loop and constant voltage (V). In a cardiac cycle, the sensing current of the T-LVAD was inverse to the speed. The flow of the T-LVAD at the 4 stages was measured individually and analyzed with different control voltages from 10 to 18 V. The highest flow ratio of MVC-AVC/AVC-MVC was noted when the T-LVAD worked on 14 V. By using analysis methodology of the flow ratio of a cardiac cycle, the optimal physiologically effective control of the T-LVAD might be achieved. PMID:11531711

Chou, N K; Wang, S S; Chu, S H; Chen, Y S; Lin, Y H; Chang, C J; Shyu, J J; Jan, G J

2001-08-01

164

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

165

Low NPSH process pumps solve instability problems in fuel-grade ethanol plant  

SciTech Connect

South Point Ethanol, one of the nation's largest producers of denatured ethyl alcohol for blending with motor fuels, encountered severe instability problems with certain pumps when the plant in South Point, Ohio went on-stream in September 1982. The ethanol is produced by fermenting the starch in cooked corn and other grains. Two 4 x 3'' centrifugal pumps with 13'' casing and 11'' impellers were originally installed to transfer the 185/sup 0/F slurry of cooked grain, or mash, through a series of coolers and into the fermenters. The single stage pumps were driven by 3600 rpm motors to provide flow rates to 600 gpm and up to 480' tdh, but developed instability problems due to the high tip speed of the 11'' impellers. The pumps transferring the degassed beer were replaced with pumps which feature a semi-open reverse vane impeller that is specifically designed to minimize stuffing box pressure and provide superior performance when operating at very low net positive suction head (NPSH) with volatile and near-boiling fluids. Two 6 x 4 x 10'' pumps with the reverse vane, low NPSH impeller were purchased to replace the 4 x 3 x 13'' mash transfer pumps that had to be overhauled about once a week. The new pumps were installed on the same bases and are driven by the original 3600 rpm electric motors. The four pumps have provided smooth, trouble-free transfer of the hot mash and degassed beer for over a year without any replacement parts or other than routine maintenance. The plant currently operates about 40 of the pumps in sizes from 1 1/2 x 1 x 6'' to 10 x 8 x 16'' to provide flow rates to 825 gpm and up to 490' tdh in various applications.

Andersen, R.B.; Gaines, A.

1984-12-01

166

Viscous Hydraulic Jumps Submitted by  

E-print Network

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

Bush, John W.M.

167

Numerical analysis of rotating stall instabilities of a pump- turbine in pump mode  

NASA Astrophysics Data System (ADS)

Rotating stall may occur at part load flow of a pump-turbine in pump mode. Unstable flow structures developing under stall condition can lead to a sudden drop of efficiency, high dynamic load and even cavitation. CFD simulations on a pump-turbine model in pump mode were carried out to reveal the onset and developed mechanisms of these unstable flow phenomena at part load. The simulation results of energy-discharge and efficiency characteristics are in good agreement with those obtained by experiments. The more deviate from design conditions with decreasing flow rate, the more flow separations within the vanes. Under specific conditions, four stationary separation zones begin to progress on the circumference, rotating at a fraction of the impeller rotation rate. Rotating stalls lead to the flow in the vane diffuser channels alternating between outward jet flow and blockage. Strong jets impact the spiral casing wall causing high pressure pulsations. Severe separations of the stall cells disturb the flow inducing periodical large amplitude pressure fluctuations, of which the intensity at different span wise of the guide vanes is different. The enforced rotating nonuniform pressure distributions on the circumference lead to dynamic uniform forces on the impeller and guide vanes. The results show that the CFD simulations are capable to gain the complicated flow structure information for analysing the unstable characteristics of the pump mode at part load.

Xia, L. S.; Cheng, Y. G.; Zhang, X. X.; Yang, J. D.

2014-12-01

168

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

169

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

E-print Network

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

Lusardi, Christopher (Christopher Dean)

2012-01-01

170

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

E-print Network

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

Walton, Edward James

2014-01-01

171

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

E-print Network

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

Everitt, Jonathan (Jonathan Neil)

2014-01-01

172

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

NASA Technical Reports Server (NTRS)

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

Moore, Joan G.; Moore, John

1992-01-01

173

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

174

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

Microsoft Academic Search

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

J. Nowacki

2004-01-01

175

Reduced-order modeling for mistuned centrifugal impellers with crack damages  

NASA Astrophysics Data System (ADS)

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

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

2014-12-01

176

Viscous Marangoni propulsion  

E-print Network

Marangoni propulsion is a form of locomotion wherein an asymmetric release of surfactant by a body located at the surface of a liquid leads to its directed motion. We present in this paper a mathematical model for Marangoni propulsion in the viscous regime. We consider the case of a thin rigid circular disk placed at the surface of a viscous fluid and whose perimeter has a prescribed concentration of an insoluble surfactant, to which the rest of its surface is impenetrable. Assuming a linearized equation of state between surface tension and surfactant concentration, we derive analytically the surfactant, velocity and pressure fields in the asymptotic limit of low Capillary, Peclet and Reynolds numbers. We then exploit these results to calculate the Marangoni propulsion speed of the disk. Neglecting the stress contribution from Marangoni flows is seen to over-predict the propulsion speed by 50%.

Eric Lauga; Anthony M. J. Davis

2012-12-05

177

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

E-print Network

. The transformation matrix in this case may be given as: (19) where [J[ is for the undistorted frame of reference and [J~ is given for a distorted frame as follows: 50 , , a& ' , , ac ' , , a( BN. ' x, . P ? ')I, P ? 'z, . , , an ' , , an (20) o BN..., , , af , , a& , , a( The spatial derivative operator is given as follows: a Bx a By a az = ( [ T] +e (Pl ) a a( a an a (21) where the T matrix is defined in conjunction with equation (11) and the P matrix is defined as follows: (" BN, "BN...

Daniel, Arul Sathyasundar

2012-06-07

178

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

E-print Network

for finding the frequency of free vibration as well as system stability. All results lead to the conclusion that the forces have little influence on natural frequency but can have appreciable effects on system stability. Specifically, at higher values.... Figure 15. Frequency response: whirl amplitude. Frequency response: phase angle, Rotor orbit during free vibration. Time history of rotor whirl frequency ratio during free vibration, 32 32 36 36 Figure 16. Figure 17. Rotor orbit during...

Williams, James Philip

2012-06-07

179

Viscous froth lens  

NASA Astrophysics Data System (ADS)

Microscale models of foam structure traditionally incorporate a balance between bubble pressures and surface tension forces associated with curvature of bubble films. In particular, models for flowing foam microrheology have assumed this balance is maintained under the action of some externally imposed motion. Recently, however, a dynamic model for foam structure has been proposed, the viscous froth model, which balances the net effect of bubble pressures and surface tension to viscous dissipation forces: this permits the description of fast-flowing foam. This contribution examines the behavior of the viscous froth model when applied to a paradigm problem with a particularly simple geometry: namely, a two-dimensional bubble “lens.” The lens consists of a channel partly filled by a bubble (known as the “lens bubble”) which contacts one channel wall. An additional film (known as the “spanning film”) connects to this bubble spanning the distance from the opposite channel wall. This simple structure can be set in motion and deformed out of equilibrium by applying a pressure across the spanning film: a rich dynamical behavior results. Solutions for the lens structure steadily propagating along the channel can be computed by the viscous froth model. Perturbation solutions are obtained in the limit of a lens structure with weak applied pressures, while numerical solutions are available for higher pressures. These steadily propagating solutions suggest that small lenses move faster than large ones, while both small and large lens bubbles are quite resistant to deformation, at least for weak applied back pressures. As the applied back pressure grows, the structure with the small lens bubble remains relatively stiff, while that with the large lens bubble becomes much more compliant. However, with even further increases in the applied back pressure, a critical pressure appears to exist for which the steady-state structure loses stability and unsteady-state numerical simulations show it breaks up by route of a topological transformation.

Green, T. E.; Bramley, A.; Lue, L.; Grassia, P.

2006-11-01

180

VISCOUS CHARACTERICTICS ANALYSIS  

NASA Technical Reports Server (NTRS)

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

Jenkins, R. V.

1994-01-01

181

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

182

Effect of the collector tube profile on Pitot pump performances  

NASA Astrophysics Data System (ADS)

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

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

2013-12-01

183

Flow Analysis of the Cleveland Clinic Centrifugal Pump  

NASA Technical Reports Server (NTRS)

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

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

1997-01-01

184

Insulin Pumps  

MedlinePLUS

... Size: A A A Listen En Espańol Insulin Pumps Insulin pumps are small computerized devices that deliver insulin in ... tissue and is taped in place. The insulin pump is not an artificial pancreas (because you still ...

185

Impeller leakage flow modeling for mechanical vibration control  

NASA Technical Reports Server (NTRS)

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

Palazzolo, Alan B.

1996-01-01

186

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

NASA Astrophysics Data System (ADS)

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

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

2014-12-01

187

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

188

DownHole Emulsification for Improving Viscous Crude Production  

Microsoft Academic Search

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

R. SIMON; W. G. POYNTER

1968-01-01

189

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

NASA Technical Reports Server (NTRS)

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

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

1992-01-01

190

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

NASA Astrophysics Data System (ADS)

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

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

1992-07-01

191

Micropump for viscous liquids and muds  

NASA Astrophysics Data System (ADS)

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

Schwesinger, Norbert; Bechtel, Sasha

1998-09-01

192

Inducer analysis/pump model development  

NASA Astrophysics Data System (ADS)

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

Cheng, Gary C.

1994-03-01

193

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

PubMed

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

Logan, R; Briens, L

2012-11-01

194

Unilateral contact induced blade/casing vibratory interactions in impellers: Analysis for rigid casings  

NASA Astrophysics Data System (ADS)

This contribution addresses the vibratory analysis of unilateral-contact induced structural interactions between a bladed impeller and its surrounding rigid casing. Such assemblies can be found in helicopter or small aircraft engines for instance and the interactions of interest shall arise due to the always tighter operating clearances between the rotating and stationary components. The investigation is conducted by extending to cyclically symmetric structures an in-house time-marching based tool dedicated to unilateral contact occurrences in turbomachines. The main components of the considered impeller together with the associated assumptions and modelling principles considered in this work are detailed. Typical dynamical features of cyclically symmetric structures, such as the aliasing effect and frequency clustering are explored in this nonlinear framework by means of thorough frequency-domain analyses and harmonic trackings of the numerically predicted impeller displacements. Additional contact maps highlight the existence of critical rotational velocities at which displacements potentially reach high amplitudes due to the synchronization of the bladed assembly vibratory pattern with the shape of the rigid casing. The proposed numerical investigations are also compared to a simpler and (almost) empirical criterion: it is suggested, based on nonlinear numerical simulations with a linear reduced order model of the impeller and a rigid casing, that this criterion may miss important critical velocities emanating from the unfavorable combination of aliasing and contact-induced higher harmonics in the vibratory response of the impeller. Overall, this work suggests a way to enhance guidelines to improve the design of impellers in the context of nonlinear and nonsmooth dynamics.

Batailly, Alain; Meingast, Markus; Legrand, Mathias

2015-02-01

195

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

196

Combustion of viscous hydrocarbons  

SciTech Connect

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

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

1987-08-04

197

Viscous starting jets  

NASA Technical Reports Server (NTRS)

The transient motion which is produced when a viscous incompressible fluid is forced from an initial state of rest is studied. The equations for unsteady particle paths, written in terms of similarity variables, are analyzed as a quasi-autonomous system with the Reynolds number treated as a parameter. By finding and classifying critical points in the system's phase portrait, the flow structure is examined. It is shown that: (1) bifurcations in the phase portrait occur at specific values of the Reynolds number of the flow in question, and (2) the exact solutions of the Stokes equations for the low-Reynolds-number limit contain two critical Reynolds numbers and three distinct states of motion which culminate in the onset of a vortex roll-up.

Cantwell, Brian J.

1986-01-01

198

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

NASA Technical Reports Server (NTRS)

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

Eckardt, D.

1978-01-01

199

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

NASA Astrophysics Data System (ADS)

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

Liu, Xiaodong; Fu, Bao; Zhuang, Ming

2014-03-01

200

Well pumping  

SciTech Connect

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

Bohon, W.M.

1992-09-08

201

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

NASA Astrophysics Data System (ADS)

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

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

2012-01-01

202

32 Scientific American, January 2014 Photograph by Tktk Tktk Unconscious impulses and desires impel  

E-print Network

scientists who study the mind. Sigmund Freud's massive body of work emphasized the conscious as the locus many of our atti- tudes toward others. Sigmund Freud meditated on the mean- ing of the unconscious and desires impel what we think and do in ways Freud never dreamed of By John A. Bargh psychology Unconscious

Bargh, John A.

203

Modelling of the Turbulent Wall Jet Generated by a Pitched Blade Turbine Impeller  

Microsoft Academic Search

CFD modelling results have been presented for a flat-bottomed tank with a pitched blade turbine impeller and four baffles. Four turbulence models, i.e. the standard k- ?, the RNG k-?, the realizable k-? and the Reynolds stress model have been used in the modelling. The simulated values of the tangential and axial mean velocity components along with the kinetic energy

Zdzislaw Jaworski; Barbara Zakrzewska

2002-01-01

204

Impeller flow field characterization with a laser two-focus velocimeter  

Microsoft Academic Search

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

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

1993-01-01

205

Impelling and Inhibiting Forces in the Perpetration of Intimate Partner Violence  

E-print Network

Impelling and Inhibiting Forces in the Perpetration of Intimate Partner Violence Eli J. Finkel violence, domestic violence, aggression, self-regulation Spouse A and Spouse B have been married for two Northwestern University The huge corpus of research identifying risk factors for intimate partner violence (IPV

Reber, Paul J.

206

Review on stress corrosion and corrosion fatigue failure of centrifugal compressor impeller  

NASA Astrophysics Data System (ADS)

Corrosion failure, especially stress corrosion cracking and corrosion fatigue, is the main cause of centrifugal compressor impeller failure. And it is concealed and destructive. This paper summarizes the main theories of stress corrosion cracking and corrosion fatigue and its latest developments, and it also points out that existing stress corrosion cracking theories can be reduced to the anodic dissolution (AD), the hydrogen-induced cracking (HIC), and the combined AD and HIC mechanisms. The corrosion behavior and the mechanism of corrosion fatigue in the crack propagation stage are similar to stress corrosion cracking. The effects of stress ratio, loading frequency, and corrosive medium on the corrosion fatigue crack propagation rate are analyzed and summarized. The corrosion behavior and the mechanism of stress corrosion cracking and corrosion fatigue in corrosive environments, which contain sulfide, chlorides, and carbonate, are analyzed. The working environments of the centrifugal compressor impeller show the behavior and the mechanism of stress corrosion cracking and corrosion fatigue in different corrosive environments. The current research methods for centrifugal compressor impeller corrosion failure are analyzed. Physical analysis, numerical simulation, and the fluid-structure interaction method play an increasingly important role in the research on impeller deformation and stress distribution caused by the joint action of aerodynamic load and centrifugal load.

Sun, Jiao; Chen, Songying; Qu, Yanpeng; Li, Jianfeng

2015-01-01

207

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

NASA Technical Reports Server (NTRS)

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

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

1997-01-01

208

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

209

Interacting viscous dark fluids  

NASA Astrophysics Data System (ADS)

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

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

2013-12-01

210

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

NASA Astrophysics Data System (ADS)

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

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

2015-02-01

211

Heat pumps  

NSDL National Science Digital Library

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

Iowa Public Television. Explore More Project

2004-01-01

212

Injector pump  

Microsoft Academic Search

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

A. L. Dunn; H. Hill

1978-01-01

213

Pump It!  

NSDL National Science Digital Library

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

2014-09-18

214

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

NASA Technical Reports Server (NTRS)

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

Pampreen, R. C.

1977-01-01

215

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

216

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

NASA Astrophysics Data System (ADS)

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

Huang, D.; Pan, Z. Y.

2015-01-01

217

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

PubMed

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

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

2013-11-01

218

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

219

Heart Pump Design for Cleveland Clinic Foundation  

NASA Technical Reports Server (NTRS)

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

2005-01-01

220

An integrated framework of tool path planning in 5-axis machining of centrifugal impeller with split blades  

Microsoft Academic Search

Centrifugal impeller is a complex part commonly used in aerospace, energy, and air-conditioning industries. Its manufacture\\u000a involves multi-axis free form machining, a time consuming and error-prone process. Tool path planning is considered a critical\\u000a issue in the process but still lacking of systematic solutions. This paper proposes a tool path planning framework for 5-axis\\u000a machining of centrifugal impeller with split

Chih-Hsing Chu; Yu-Wei Li

221

Fluorescent image tracking velocimetry of the Nimbus AxiPump.  

PubMed

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

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

1993-01-01

222

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

223

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

224

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

PubMed Central

The helicity of DNA and its long-range chiral packing are widespread phenomena; however, the packing mechanism remains poorly understood both in vivo and in vitro. Here, we report the extraordinary DNA chiral self-assembly by silica mineralization, together with circular dichroism measurements and electron microscopy studies on the structure and morphology of the products. Mg2+ ion and diethylenetriamine were found to induce right- and left-handed chiral DNA packing with two-dimensional-square p4mm mesostructures, respectively, to give corresponding enantiomeric impeller-like helical DNA–silica complexes. Moreover, formation of macroscopic impeller-like helical architectures depends on the types of polyamines and co-structure-directing agents and pH values of reaction solution. It has been suggested that interaction strength between negatively charged DNA phosphate strands and positively charged counterions may be the key factor for the induction of DNA packing handedness. PMID:24098845

Liu, Ben; Han, Lu; Che, Shunai

2012-01-01

225

Optimization of centrifugal pump cavitation performance based on CFD  

NASA Astrophysics Data System (ADS)

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

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

2015-01-01

226

Quantifying mixing in viscously unstable porous media flows  

E-print Network

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

Jha, Birendra

227

Investigation of tool orientation for milling blade of impeller in five-axis machining  

Microsoft Academic Search

In this paper, a method to determine the optimal tool orientation to make a more perfect impeller blade surface using a five-axis\\u000a flank milling machine is presented. Verification of surface geometric accuracy using a 3D coordinate measuring machine is\\u000a also shown. A mathematical formula is derived which includes the parameters of tool and curved surface to calculate the appropriate\\u000a tool

Kuan-Hung Chen

2011-01-01

228

Simulation of the unsteady interaction of a centrifugal impeller with its vaned diffuser: flow analysis  

Microsoft Academic Search

The aim of this paper is to help advance our understanding of the complex, three-dimensional, unsteady flow associated with the interaction of a splittered centrifugal impeller and its vaned diffuser. A time-resolved simulation is presented of the Krain stage performed using a time-accurate, three-dimensional, unstructured mesh, solution-adaptive Navier-Stokes solver. The predicted flowfield, compared with experiment where available, displays a complex,

W. N. Dawes

1995-01-01

229

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

E-print Network

A FINITE ELEMENT MODEL OF THE TURBULENT FLOW FIELD IN A CENTRIFUGAL IlVPELLER A Thesis by STEVEN TODD HLAVATY Submitted to the Office of Graduate Studies of Texas A&M University in partial fulfillment of the requirements for the degree... of MASTER OF SCIENCE August 1993 Major Subject: Mechanical Engineering A FINITE ELEMENT MODEL OF THE TURBULENT FLOW FIELD IN A CENTRIFUGAL IMPELLER A Thesis by STEVEN TODD HLAVATY Submitted to Texas A&M University in partial fulfillment...

Hlavaty, Steven Todd

2012-06-07

230

Study of Impeller Design for Pipe Flow Generator with CFD and RP  

Microsoft Academic Search

Design optimization is performed in this study for Pipe Flow Generator. Emphasize are on the impeller parameters including the geometry and the number of the blades. Modern engineering tools such as Computational-Fluid-Dynamics software and Rapid-Prototyping technology are utilized, to facilitate both numerical and experimental studies. In CFD numerical simulation, two dimensional transient analyses are conducted to investigate the relationship between

Song-Hao Wang; Carlos Fernando Hernandez Porres; Mong-Yee Zuo; Wen-Jia Xiao

2010-01-01

231

Small centrifugal pumps for low-thrust rocket engines  

NASA Technical Reports Server (NTRS)

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

Furst, R. B.

1986-01-01

232

Application of an artificial neural network to pump card diagnosis  

SciTech Connect

Beam pumping is the most frequently used artificial-lift technique for oil production. Downhole pump cards are used to evaluate performance of the pumping unit. Pump cards can be generated from surface dynamometer cards using a 1D wave equation with viscous damping, as suggested by Gibbs and Neely. Pump cards contain significant information describing the behavior of the pump. However, interpretation of these cards is tedious and time-consuming; hence, an automated system capable of interpreting these cards could speed interpretation and warn of pump failures. This work presents the results of a DOS-based computer program capable of correctly classifying pump cards. The program uses a hybrid artificial neural network (ANN) to identify significant features of the pump card. The hybrid ANN uses classical and sinusoidal perceptrons. The network is trained using an error-back-propagation technique. The program correctly identified pump problems for more than 180 different training and test pump cards. The ANN takes a total of 80 data points as input. Sixty data points are collected from the pump card perimeter, and the remaining 20 data points represent the slope at selected points on the pump card perimeter. Pump problem conditions are grouped into 11 distinct classes. The network is capable of identifying one or more of these problem conditions for each pump card. Eight examples are presented and discussed.

Ashenayi, K. (Univ. of Tulsa, OK (United States)); Lea, J.F. (Amoco Production Research, Tulsa, OK (United States)); Kemp, F. (Kemp (Franklin), Dallas, TX (United States)); Nazi, G.A.

1994-12-01

233

Fjords in viscous fingering: selection of width and opening scale  

SciTech Connect

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

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

2008-01-01

234

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

PubMed

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

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

2011-08-01

235

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

236

Centrifugal Pump Test Bed: A Senior Capstone Project  

NSDL National Science Digital Library

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

Choate, Robert

237

Modeling gas-liquid head performance of electrical submersible pumps  

NASA Astrophysics Data System (ADS)

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

Sun, Datong

238

Ferroelectric Pump  

NASA Technical Reports Server (NTRS)

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

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

2000-01-01

239

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

PubMed

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

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

2012-04-01

240

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

NASA Astrophysics Data System (ADS)

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

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

2014-10-01

241

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

242

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

NASA Astrophysics Data System (ADS)

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

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

2005-04-01

243

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

2008-10-01

244

Determination of the cavitation characteristics of vane pumps in the presence of a ''scale effect''  

SciTech Connect

This article explains how the use of impeller cavitation locking conditions in the presence of a cavitation scale effect provides a means of substantially reducing the number of tests required to obtain the cavitation characteristics for several fixed values of one of the liquid parameters causing the appearance of the cavitation scale effect. By using the method proposed, 4 tests are required in total. Points out that the new method of testing the pump is less laborious since it does not require maintaining constant to a high accuracy for the total test period the parameters of the pumped liquid which determine the cavitation scale effect.

Shcherbatenko, I.V.

1982-09-01

245

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

246

Competition between anisotropic viscous fingers  

NASA Astrophysics Data System (ADS)

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

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

2014-09-01

247

Particle stress and viscous compaction  

SciTech Connect

This study describes the transition between the quasi-static and the viscous regimes of shearing of thin layers of spheres in a viscous fluid at high solid loadings. Experiments were conducted in a Couette-type shear cell in two complementary modes: (a) constant particle normal stress, variable solid fraction and (b) constant solid fraction, variable particle normal stress. In steady shearing under the constraint of constant solid fraction, transition from a strain rate independent stress to a linearly dependent on was found to occur with a local minimum in the stresses with respect to strain rage; correspondingly, the solid fraction assumed a maximum with respect to strain rate under conditions of constant normal stress. At sufficiently high strain rates, the mixture exhibited a linear Newtonian-like scaling between strain rate and both shear and normal stresses. These measurements of normal stress are the first since those of Bagnold (1954).

Prasad, D.; Kytoemaa, H.K. [Massachusetts Inst. of Tech., Cambridge, MA (United States). Dept. of Mechanical Engineering

1994-12-31

248

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

249

Using a Breast Pump  

MedlinePLUS

... Breast Pump and Breastfeeding Resources Using a Breast Pump Before using your breast pump for the first ... pump movie ) General Tips for Using a Breast Pump Wash and Dry Your Hands Before using your ...

250

Types of Breast Pumps  

MedlinePLUS

... Breast Pump and Breastfeeding Resources Types of Breast Pumps All breast pumps consist of a few basic ... used for feeding a baby. Types of Breast Pumps There are three basic types of breast pumps: ...

251

Theory of laminar viscous jets  

NASA Astrophysics Data System (ADS)

Results of recent theoretical studies of laminar jet flows of a viscous incompressible fluid are reviewed. In particular, attention is given to plane, fan-shaped, axisymmetric, and swirling jet flows; jet flows behind bodies; and slipstream jet flows. The discussion also covers dissipation of mechanical energy in jet flows, jet flows with a zero excess momentum, and asymptotic series expansions in the theory of jet flows.

Martynenko, O. G.; Korovkin, V. N.; Sokovishin, Iu. A.

252

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

NASA Astrophysics Data System (ADS)

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

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

2015-01-01

253

Computational Study of the CC3 Impeller and Vaneless Diffuser Experiment  

NASA Technical Reports Server (NTRS)

Centrifugal compressors are compatible with the low exit corrected flows found in the high pressure compressor of turboshaft engines and may play an increasing role in turbofan engines as engine overall pressure ratios increase. Centrifugal compressor stages are difficult to model accurately with RANS CFD solvers. A computational study of the CC3 centrifugal impeller in its vaneless diffuser configuration was undertaken as part of an effort to understand potential causes of RANS CFD mis-prediction in these types of geometries. Three steady, periodic cases of the impeller and diffuser were modeled using the TURBO Parallel Version 4 code: 1) a k-epsilon turbulence model computation on a 6.8 million point grid using wall functions, 2) a k-epsilon turbulence model computation on a 14 million point grid integrating to the wall, and 3) a k-omega turbulence model computation on the 14 million point grid integrating to the wall. It was found that all three cases compared favorably to data from inlet to impeller trailing edge, but the k-epsilon and k-omega computations had disparate results beyond the trailing edge and into the vaneless diffuser. A large region of reversed flow was observed in the k-epsilon computations which extended from 70% to 100% span at the exit rating plane, whereas the k-omega computation had reversed flow from 95% to 100% span. Compared to experimental data at near-peak-efficiency, the reversed flow region in the k-epsilon case resulted in an under-prediction in adiabatic efficiency of 8.3 points, whereas the k-omega case was 1.2 points lower in efficiency.

Kulkarni, Sameer; Beach, Timothy A.; Skoch, Gary J.

2013-01-01

254

Computational Study of the CC3 Impeller and Vaneless Diffuser Experiment  

NASA Technical Reports Server (NTRS)

Centrifugal compressors are compatible with the low exit corrected flows found in the high pressure compressor of turboshaft engines and may play an increasing role in turbofan engines as engine overall pressure ratios increase. Centrifugal compressor stages are difficult to model accurately with RANS CFD solvers. A computational study of the CC3 centrifugal impeller in its vaneless diffuser configuration was undertaken as part of an effort to understand potential causes of RANS CFD mis-prediction in these types of geometries. Three steady, periodic cases of the impeller and diffuser were modeled using the TURBO Parallel Version 4 code: (1) a k-e turbulence model computation on a 6.8 million point grid using wall functions, (2) a k-e turbulence model computation on a 14 million point grid integrating to the wall, and (3) a k-? turbulence model computation on the 14 million point grid integrating to the wall. It was found that all three cases compared favorably to data from inlet to impeller trailing edge, but the k-e and k-? computations had disparate results beyond the trailing edge and into the vaneless diffuser. A large region of reversed flow was observed in the k-e computations which extended from 70 to 100 percent span at the exit rating plane, whereas the k-? computation had reversed flow from 95 to 100 percent span. Compared to experimental data at near-peak-efficiency, the reversed flow region in the k-e case resulted in an underprediction in adiabatic efficiency of 8.3 points, whereas the k-? case was 1.2 points lower in efficiency.

Kulkarni, Sameer; Beach, Timothy A.; Skoch, Gary J.

2013-01-01

255

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

NASA Technical Reports Server (NTRS)

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

Beede, William L.; Kovach, Karl

1948-01-01

256

Fluctuating pressures in pump diffuser and collector scrolls, part 1  

NASA Technical Reports Server (NTRS)

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.

1989-01-01

257

Heat pump  

SciTech Connect

A heat pump is disclosed that is, driven by a free piston engine, wherein a refrigeration type of heat transfer unit is used and no externally energized electric motors are required but could be used, if desired. The engine is larger in horsepower than would be required for driving the compressor of the unit only, as it also provides power for driving one or more gas driven or other motors for forcing air through heat exchangers. This arrangement requires substantially less total energy than a unit requiring external electrical energy for operating portions of the heat pumps in that the extra heat in the exhaust from the larger horsepower engine is utilized in a heat exchanger to supply extra heat to the space being heated by the heat pump's primary heat supplier.

Braun, A.

1981-10-06

258

Relativistic Shock Waves in Viscous Gluon Matter  

SciTech Connect

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

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

2009-07-17

259

Gastrostomy feeding tube - pump  

MedlinePLUS

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

260

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

E-print Network

A method for determining the turbulent flow through the leakage passage in rotating machinery has been enhanced to allow for the modeling of complex multiplyconnected flow domains such as that of the combined primary and secondary flow passages...

Wyman, Nicholas James

1994-01-01

261

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

262

Inhomogeneous viscous fluids for inflation  

E-print Network

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

Ratbay Myrzakulov; Lorenzo Sebastiani

2014-11-18

263

Mass transfer of RAFM steel in Li by simple immersion, impeller induced flow and thermal convection  

NASA Astrophysics Data System (ADS)

The compatibility of reduced activation ferritic steel, JLF-1, was investigated by the corrosion tests in static lithium (Li), impeller induced Li flow and thermal convection Li. A simple model for corrosion of JLF-1 in Li was based on the equation of mass transfer and mass balance in the corrosion test. Solubility of Cr in Li was evaluated as 37.6 wppm at 500 °C and 77.2 wppm at 600 °C based on the data obtained in corrosion tests in static Li. The mass transfer coefficient of the dissolved Cr from the steel in static Li was experimentally determined to be 4.08 × 10 -8 m/s at 500 °C and 1.81 × 10 -7 m/s at 600 °C. The mass transfer coefficient for impeller induced flow calculated from Sherwood number and literature value of the diffusion coefficient was 1.34 × 10 -4 m/s at 500 °C and 1.40 × 10 -4 m/s at 600 °C. Theoretical values for the corrosion loss were compared with values obtained from the experimental data. The mass transfer coefficient determined for the thermal convection loop was 1.73 × 10 -5 m/s.

Kondo, Masatoshi; Muroga, Takeo; Nagasaka, Takuya; Xu, Qi; Tsisar, Valentyn; Oshima, Tomoko

2011-10-01

264

A simulation of the unsteady interaction of a centrifugal impeller with its vaned diffuser: Flow analysis  

SciTech Connect

The aim of this paper is to help advance one`s understanding of the complex, three-dimensional, unsteady flow associated with the interaction of a splittered centrifugal impeller and its vaned diffuser. A time-resolved simulation is presented of the Krain stage performed using a time-accurate, three-dimensional, unstructured mesh, solution-adaptive Navier-Stokes solver. The predicted flowfield, compared with experiment where available, displays a complex, unsteady interaction, especially in the neighborhood of the diffuser entry zone, which experiences large periodic flow unsteadiness. Downstream of the throat, although the magnitude of this unsteadiness diminishes rapidly, the flow has a highly distorted three-dimensional character. The loss levels in the diffuser are then investigated to try and determine how time-mean loss levels compare with the levels expected from equivalent steady flow analysis performed by using the circumferentially averaged exit flow from the impeller as inlet to the diffuser. It is concluded that little loss could be attributed directly to unsteady effects but rather that the principal cause of the rather high loss levels observed in the diffuser is the strong spanwise distortion in swirl angle at inlet, which initiates a strong hub/corner stall.

Dawes, W.N. [Whittle Lab., Cambridge (United Kingdom)

1995-04-01

265

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

266

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

267

Effect of soft-iron impellers on the von Kármán-sodium dynamo.  

PubMed

The explanation for the observed axisymmetric magnetic field in the von Kármán-sodium (VKS) dynamo experiment is still an unresolved question. In this paper, the integral equation approach is extended to investigate the VKS dynamo action by taking into account the discontinuity of the magnetic permeability and electrical conductivity in the conducting region. When the relative magnetic permeability of the soft-iron impellers is set to 65, a steady toroidal field that is apparently axisymmetric is excited at the critical magnetic Reynolds number, Rmc?27.23, which is close to the experimental result, Rmc?30. Our results show that the critical magnetic Reynolds number declines as the relative magnetic permeability of the impellers increases. Furthermore, when the relative magnetic permeability is not greater than 37, an equatorial magnetic field with an azimuthal wave number m=1 is the dominant mode, otherwise a steady toroidal field with an azimuthal wave number m=0 predominates the magnetic field generated by the VKS dynamo action. PMID:24580325

Xu, Mingtian

2014-01-01

268

Effect of soft-iron impellers on the von Kármán-sodium dynamo  

NASA Astrophysics Data System (ADS)

The explanation for the observed axisymmetric magnetic field in the von Kármán-sodium (VKS) dynamo experiment is still an unresolved question. In this paper, the integral equation approach is extended to investigate the VKS dynamo action by taking into account the discontinuity of the magnetic permeability and electrical conductivity in the conducting region. When the relative magnetic permeability of the soft-iron impellers is set to 65, a steady toroidal field that is apparently axisymmetric is excited at the critical magnetic Reynolds number, Rmc?27.23, which is close to the experimental result, Rmc?30. Our results show that the critical magnetic Reynolds number declines as the relative magnetic permeability of the impellers increases. Furthermore, when the relative magnetic permeability is not greater than 37, an equatorial magnetic field with an azimuthal wave number m =1 is the dominant mode, otherwise a steady toroidal field with an azimuthal wave number m =0 predominates the magnetic field generated by the VKS dynamo action.

Xu, Mingtian

2014-01-01

269

Creep Property Characterization of Potential Brayton Cycle Impeller and Duct Materials  

NASA Technical Reports Server (NTRS)

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

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

2007-01-01

270

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

NASA Technical Reports Server (NTRS)

This paper represents a status report documenting the work on creep of superalloys performed under Project Prometheus. Cast superalloys have potential applications in space as impellers within closed-loop Brayton cycle nuclear power generation systems. Likewise wrought superalloys are good candidates for ducts and heat exchangers transporting the inert working gas in a Brayton-based power plant. Two cast superalloys, Mar-M247LC and IN792, and a NASA GRC powder metallurgy superalloy, LSHR, are being screened to compare their respective capabilities for impeller applications. Several wrought superalloys including Hastelloy X, (Haynes International, Inc., Kokomo, IN), Inconel 617, Inconel 740, Nimonic 263, and Incoloy MA956 (Special Metals Corporation, Huntington, WV) are also being screened to compare their capabilities for duct applications. These proposed applications would require sufficient strength and creep resistance for long term service at temperatures up to 1200 K, with service times to 100,000 h or more. Conventional tensile and creep tests were performed at temperatures up to 1200 K on specimens extracted from the materials. Initial microstructure evaluations were also undertaken.

Gabb, Timothy P.; Gayda, John

2006-01-01

271

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

SciTech Connect

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

Sloan, Benjamin

2013-05-15

272

Creep Property Characterization of Potential Brayton Cycle Impeller and Duct Materials  

NASA Astrophysics Data System (ADS)

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

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

2007-01-01

273

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

USGS Publications Warehouse

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

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

2005-01-01

274

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

NASA Astrophysics Data System (ADS)

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

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

2013-12-01

275

Pumping Myocytes  

NSDL National Science Digital Library

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

2010-01-01

276

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

PubMed

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

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

2010-08-01

277

Viscous Design of TCA Configuration  

NASA Technical Reports Server (NTRS)

The goal in this effort is to redesign the baseline TCA configuration for improved performance at both supersonic and transonic cruise. Viscous analyses are conducted with OVERFLOW, a Navier-Stokes code for overset grids, using PEGSUS to compute the interpolations between overset grids. Viscous designs are conducted with OVERDISC, a script which couples OVERFLOW with the Constrained Direct Iterative Surface Curvature (CDISC) inverse design method. The successful execution of any computational fluid dynamics (CFD) based aerodynamic design method for complex configurations requires an efficient method for regenerating the computational grids to account for modifications to the configuration shape. The first section of this presentation deals with the automated regridding procedure used to generate overset grids for the fuselage/wing/diverter/nacelle configurations analysed in this effort. The second section outlines the procedures utilized to conduct OVERDISC inverse designs. The third section briefly covers the work conducted by Dick Campbell, in which a dual-point design at Mach 2.4 and 0.9 was attempted using OVERDISC; the initial configuration from which this design effort was started is an early version of the optimized shape for the TCA configuration developed by the Boeing Commercial Airplane Group (BCAG), which eventually evolved into the NCV design. The final section presents results from application of the Natural Flow Wing design philosophy to the TCA configuration.

Krist, Steven E.; Bauer, Steven X. S.; Campbell, Richard L.

1999-01-01

278

Computational Approach for Developing Blood Pump  

NASA Technical Reports Server (NTRS)

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

Kwak, Dochan

2002-01-01

279

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

NASA Astrophysics Data System (ADS)

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

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

2012-11-01

280

Viscous-pendulum damper suppresses structural vibrations  

NASA Technical Reports Server (NTRS)

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

Reed, W. H., III

1964-01-01

281

Viscous dissipation effects in microtubes and microchannels  

Microsoft Academic Search

The effects of viscous dissipation on the temperature field and ultimately on the friction factor have been investigated using dimensional analysis and experimentally validated computer simulations. Three common working fluids, i.e., water, methanol and iso-propanol, in different conduit geometries were considered. It turns out that for microconduits, viscous dissipation is a strong function of the channel aspect ratio, Reynolds number,

J. Koo; C. Kleinstreuer

2004-01-01

282

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

Microsoft Academic Search

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

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

1992-01-01

283

Impact of Impellers on the Axisymmetric Magnetic Mode in the VKS2 Dynamo Experiment R. Laguerre,1,2  

E-print Network

to the turbulence in the bulk of the flow, but rather to the effect induced by the impellers. DOI: 10.1103/Phys for the dynamo action in liquid metal has been renewed since 2000 in the wake of successful experiments [1­3]. We]. It was argued in [5­7] that turbulence effects were responsible for the occurrence of the axisymmetric magnetic

Guermond, Jean-Luc

284

An expert system\\/neural network model (ImpelERO) for evaluating agricultural soil erosion in Andalucia region, southern Spain  

Microsoft Academic Search

Soil erosion by water is one of today’s most important environmental problems, in great part due to changes in agricultural land use and management. This paper illustrates the formulation, calibration, sensitivity and validation analysis of a hybrid model of expert decision trees and artificial neural networks (named ImpelERO) to evaluate the soil erosion process A total of 237 field units

D de la Rosa; F Mayol; J. A Moreno; T Bonsón; S Lozano

1999-01-01

285

Noise as an indicator of cavitation in a centrifugal pump  

NASA Astrophysics Data System (ADS)

One of the sources of instability in a centrifugal pump is cavitation within the pump. Cavitation of a centrifugal pump is the result of insufficient net positive suction head (NPSH) and can occur within the entire range of operating conditions. Cavitation may cause three different and undesirable effects: (1) a drop in head-capacity and efficiency curves, (2) damage to the impeller by pitting and erosion, and (3) structure vibration and resulting noise. Therefore, the cavitation process must be prevented by all means. To prevent the onset of cavitation we have to detect the beginning of the cavitation process in the pump. To detect the beginning of the cavitation process, the emitted noise can be used, among other possibilities. Specifically, a noise spectra structure can be used to detect the beginning of cavitation and its development. Experiments have shown that there is a discrete frequency tone, at 147 Hz, which is strongly dependent on the cavitation process and its development. Therefore, noise spectra can also be used to determine the NPSH required or the critical value, representing the upper limit of the permissible pump operation without cavitation.

Chudina, M.

2003-07-01

286

Radiation-viscous boundary layer  

NASA Technical Reports Server (NTRS)

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

Arav, Nahum; Begelman, Mitchell C.

1992-01-01

287

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

DOEpatents

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

Weingart, Richard C. (Livermore, CA)

1989-01-01

288

Mean-field model of the von Kármán sodium dynamo experiment using soft iron impellers  

NASA Astrophysics Data System (ADS)

It has been observed that dynamo action occurs in the von-Kármán-Sodium (VKS) experiment only when the rotating disks and the blades are made of soft iron. The purpose of this paper is to numerically investigate the role of soft iron in the VKS dynamo scenario. This is done by using a mean-field model based on an axisymmetric mean flow, a localized permeability distribution, and a localized ? effect modeling the action of the small velocity scales between the blades. The action of the rotating blades is modeled by an axisymmetric effective permeability field. Key properties of the flow giving to the numerical magnetic field a geometric structure similar to that observed experimentally are identified. Depending on the permeability of the disks and the effective permeability of the blades, the dynamo that is obtained is either oscillatory or stationary. Our numerical results confirm the leading role played by the ferromagnetic impellers. A scenario for the VKS dynamo is proposed.

Nore, C.; Léorat, J.; Guermond, J.-L.; Giesecke, A.

2015-01-01

289

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

290

Getter pumping  

E-print Network

A surface may provide a useful pumping action when able to retain adsorbed gas molecules for the duration of a given experiment. To fulfil this condition at room temperature, strong binding forces, as those resulting from chemical reactions, are required. Materials able to react with gases to form stable chemical compounds are called getters. The two main families of getters (evaporable and non-evaporable, or NEG) are presented and discussed. Special emphasis is placed on the NEG strips currently used for the vacuum systems of particle accelerators, and on the newly developed NEG thin-film coatings, in view of their possible future applications.

Benvenuti, C

2007-01-01

291

Surfactant transport on highly viscous surface films  

NASA Astrophysics Data System (ADS)

We examine surfactant transport on a highly viscous film overlying a much less viscous layer, aimed at situations within the smaller pulmonary airways, wherein the highly viscous film corresponds to the mucus layer, that rides atop the Periciliary liquid layer (PCL). To this end, we generate a variant of the lubrication approximation by promoting terms which would have otherwise been neglected within standard lubrication theory; this is reminiscent of theories involving free films, viscous jets and threads. We also account for the presence of van der Waals forces, which could rupture the thin bilayer fluid coating the small airways. This is a potential difficulty for surfactant replacement therapy (SRT) since rupture will leave behind pools of stranded surfactant thereby restricting the levels reaching the smallest airways and potentially leading to clinical failure. In the present study, the presence of the mucus for a wide range of system parameters using analytical techniques and numerical simulations.

Matar, O. K.; Craster, R. V.; Warner, M. R. E.

2002-09-01

292

The development of a cavitation free sodium pump for the breeder reactor  

SciTech Connect

The sodium pumps for a liquid metal fast breeder reactor must be designed for exceptionally high reliability and long life. The principal adverse factor which tends to limit the primary pump life is cavitation which becomes potentially severe under off-design flow conditions caused by the requirement of two loop operations which resulted in a large operating flow range. This problem prompted an extensive study which included experimental investigations of scaled down and full size pumps. The investigations involved visual observations, acoustic signature recordings, and physical characteristic measurements of the model and full size impellers. The blade configuration of the model was modified several times. After each modification intensive testing was conducted with feedback to established design criteria. The results obtained from the final configuration showed excellent cavitation performance. This configuration was then machined on the full scale impeller and tested. The results confirmed acceptable performance in the entire range of operating conditions. This paper describes the test facilities erected for this study, discusses the experimental techniques employed, and presents the experimental techniques employed, and presents a sample of the experimental results.

Baladi, J.Y.; Nyilas, C.P.

1986-12-01

293

Geothermal pump program  

SciTech Connect

The geothermal pump program for developing and testing improved downhole pumps is reviewed. Topics discussed include the Geothermal Pump Test Facility, the 80 horsepower REDA pump test, pressurized lubrication systems, the 300 horsepower REDA pump test in a MAGMA production well, advanced power, cable systems, and the East Mesa Test Facility.

Hanold, R.J.

1982-01-01

294

Numerical simulation of unsteady viscous flows  

NASA Technical Reports Server (NTRS)

Most unsteady viscous flows may be grouped into two categories, i.e., forced and self-sustained oscillations. Examples of forced oscillations occur in turbomachinery and in internal combustion engines while self-sustained oscillations prevail in vortex shedding, inlet buzz, and wing flutter. Numerical simulation of these phenomena was achieved due to the advancement of vector processor computers. Recent progress in the simulation of unsteady viscous flows is addressed.

Hankey, Wilbur L.

1987-01-01

295

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

PubMed

The effect of flow type and rotor speed was investigated in a round-bottom reactor with 5 L useful volume containing 2.0 L of granular biomass. The reactor treated 2.0 L of synthetic wastewater with a concentration of 800 mgCOD/L in 8-h cycles at 30 degrees C. Five impellers, commonly used in biological processes, have been employed to this end, namely: a turbine and a paddle impeller with six-vertical-flat-blades, a turbine and a paddle impeller with six-45 degrees -inclined-flat-blades and a three-blade-helix impeller. Results showed that altering impeller type and rotor speed did not significantly affect system stability and performance. Average organic matter removal efficiency was about 84% for filtered samples, total volatile acids concentration was below 20 mgHAc/L and bicarbonate alkalinity a little less than 400 mgCaCO3/L for most of the investigated conditions. However, analysis of the first-order kinetic model constants showed that alteration in rotor speed resulted in an increase in the values of the kinetic constants (for instance, from 0.57 h(-1) at 50 rpm to 0.84 h(-1) at 75 rpm when the paddle impeller with six-45 degrees -inclined-flat-blades was used) and that axial flow in mechanically stirred reactors is preferable over radial-flow when the vertical-flat-blade impeller is compared to the inclined-flat-blade impeller (for instance at 75 rpm, from 0.52 h(-1) with the six-flat-blade-paddle impeller to 0.84 h(-1) with the six-45 degrees -inclined-flat-blade-paddle impeller), demonstrating that there is a rotor speed and an impeller type that maximize solid-liquid mass transfer in the reaction medium. Furthermore, power consumption studies in this reduced reactor volume showed that no high power transfer is required to improve mass transfer (less than 0.6 kW/10(3)m3). PMID:18814952

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

2009-03-01

296

Using CFD to predict the behavior of power law fluids near axial-flow impellers operating in the transitional flow regime  

Microsoft Academic Search

A computational fluid dynamics (CFD) model of flow in a mixing tank with a single axial-flow impeller was developed with the FluentTM software. The model consists of an unstructured hexagonal mesh (158,000 total cells), dense in the region 5mm from the surface of the impeller. The flow was modeled as laminar and a multiple reference frame approach was used to

W. Kelly; B. Gigas

2003-01-01

297

Pumping unit  

SciTech Connect

A pumping unit is described for use at a well having a well head, comprising: support means; a pair of pitman arms, each of the pitman arms having a longitudinal axis and a first end portion and a second end portion; means including crank arm means for causing movement the pitman arms, the means for causing movement connected to the support means and to the first end portion of each of the pitman arms; a first strap having a width of at least inches and including a first end portion and a second end portion; a second strap having a width of at least three inches and including a first end portion and a second end portion, the second strap being separate from and spaced from the first strap; equalizer beam means being separate from each of the pitman arms and extending between the second end portion of each of the pitman arms. The pitman arms and the equalizer beam means cooperate with the first strap and the second strap to minimize the bending stress applied to the means for causing movement during operation of the pumping unit; connection means being separate from the equalizer beam means but engaging the equalizer beam means for use in interconnecting each of the first end portions of the first and second straps to the pitman arms and wherein each of the first and second straps contacts the equalizer beam means; and reciprocating means connected to the second end portions of the first and second straps and adapted to move relative to the well. The reciprocating means includes a polished rod and wherein all portions of the polished rod are positioned at an angle relative to the longitudinal axis of each of the pitman arms.

Pauls, D.A.

1986-12-30

298

Power consumption and circulation flow rate of polymer solutions in a stirred vessel powered by an hyperboloid impeller  

Microsoft Academic Search

An investigation was carried out to determine the power consumption, the circulating flow rate and the circulating efficiency in stirred vessel flows powered by an hyperboloid impeller. The fluids tested were dilute and semi-dilute aqueous solutions of tylose, CMC and xanthan gum (XG) at weight concentrations ranging from 0.1% to 0.6% and the solutions had varying degrees of shear-thinning and

A. S. Cavadas; F. T. Pinho

299

Liquid metal pump  

DOEpatents

The liquid metal pump comprises floating seal rings and attachment of the pump diffuser to the pump bowl for isolating structural deflections from the pump shaft bearings. The seal rings also eliminate precision machining on large assemblies by eliminating the need for a close tolerance fit between the mounting surfaces of the pump and the seals. The liquid metal pump also comprises a shaft support structure that is isolated from the pump housing for better preservation of alignment of shaft bearings. The shaft support structure also allows for complete removal of pump internals for inspection and repair.

Pennell, William E. (Greensburg, PA)

1982-01-01

300

Winding for linear pump  

DOEpatents

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

Kliman, Gerald B. (Schenectady, NY); Brynsvold, Glen V. (San Jose, CA); Jahns, Thomas M. (Schenectady, NY)

1989-01-01

301

Advanced Electric Submersible Pump Design Tool for Geothermal Applications  

SciTech Connect

Electrical Submersible Pumps (ESPs) present higher efficiency, larger production rate, and can be operated in deeper wells than the other geothermal artificial lifting systems. Enhanced Geothermal Systems (EGS) applications recommend lifting 300 C geothermal water at 80kg/s flow rate in a maximum 10-5/8-inch diameter wellbore to improve the cost-effectiveness. In this paper, an advanced ESP design tool comprising a 1D theoretical model and a 3D CFD analysis has been developed to design ESPs for geothermal applications. Design of Experiments was also performed to optimize the geometry and performance. The designed mixed-flow type centrifugal impeller and diffuser exhibit high efficiency and head rise under simulated EGS conditions. The design tool has been validated by comparing the prediction to experimental data of an existing ESP product.

Xuele Qi; Norman Turnquist; Farshad Ghasripoor

2012-05-31

302

Design and testing of a tandem row pump inducer  

NASA Technical Reports Server (NTRS)

The design and testing of a tandem row pump inducer having a supercavitating first stage with a 0.60 hub ratio is presented. The second stage tested was a helical impeller with a 0.70 hub ratio. A cubic arc transition was utilized to accomplish the hub change. The first stage had two blades and the free-vortex design approach was empirically modified based on previous experience. The recommended second stage design having four blades and using cambered blade section is presented but the model was not built or tested. The more simple helix was built instead to reduce cost. Data taken included head generation, cavitation observations and unsteady head fluctuations over the 0-100Hz range.

Etter, R. J.

1974-01-01

303

Controls of Wellbore Flow Regimes on Pump Effluent Composition  

SciTech Connect

Where well water and formation water are compositionally different or heterogeneous, pump effluent composition will vary due to partial mixing and transport induced by pumping. Investigating influences of purging and sampling methodology on composition variability requires quantification of wellbore flow regimes and mixing. As a basis for this quantification, analytical models simulating Poiseuille flow were developed to calculate flow paths and travel times. Finite element modeling was used to incorporate influences of mixing. Parabolic velocity distributions within the screened interval accelerate with cumulative inflow approaching the pump intake while an annulus of inflowing formation water contracts uniformly to displace an axial cylinder of pre-pumping well water as pumping proceeds. Increased dispersive mixing forms a more diffuse formation water annulus and the contribution of formation water to pump effluent increases more rapidly. Models incorporating viscous flow and diffusion scale mixing show that initially pump effluent is predominantly pre-pumping well water and compositions vary most rapidly. After two screen volumes of pumping, 94% of pump effluent is inflowing formation water. Where the composition of formation water and pre-pumping well water are likely to be similar, pump effluent compositions will not vary significantly and may be collected during early purging or with passive sampling. However, where these compositions are expected to be considerably different or heterogeneous, compositions would be most variable during early pumping, that is, when samples are collected during low-flow sampling. Purging of two screen volumes would be required to stabilize the content and collect a sample consisting of 94% formation water.

James Martin-Hayden; plummer; Sanford Britt

2014-01-01

304

The PediPump: development status of a new pediatric ventricular assist device: update II.  

PubMed

The PediPump is a new ventricular assist device with a hydraulic output range designed for children from newborn infants to adolescents. The design is based on a mixed-flow rotary pump; the rotating assembly consists of a front impeller, front and rear radial magnetic bearings, and a central motor magnet. Two different implantable pumps were designed initially: an intravascular pump measuring 7 x 75 mm and an extravascular pump measuring 14 x 85 mm. Current prototypes are substantially smaller: The current intravascular version measures 4.5 x 55 mm, whereas the current extravascular version measures 11 x 70 mm. Both devices provide pressure and flows capable of supporting adults, far exceeding the initially defined physiologic requirements for children weighing 2 to 25 kg. This basic pump design may be used in acute or chronic clinical settings to provide right ventricular, left ventricular, or biventricular support. There are three objectives for the PediPump development program: 1) determination of basic engineering requirements for hardware and control logic including design analysis for system sizing, evaluation of control concepts, and bench testing of prototypes; 2) performance of preclinical anatomic fitting studies using CT-based 3D modeling; and 3) animal studies to provide characterization and reliability testing of the device. PMID:16966863

Duncan, Brian W; Dudzinski, David T; Gu, Lei; Mielke, Nicole; Noecker, Angela M; Kopcak, Michael W; Fukamachi, Kiyotaka; Cingoz, Faruk; Ootaki, Yoshio; Smith, William A

2006-01-01

305

Simulation of 3-D viscous compressible flow in multistage turbomachinery by finite element methods  

NASA Astrophysics Data System (ADS)

The flow in a multistage turbomachinery blade row is compressible, viscous, and unsteady. Complex flow features such as boundary layers, wake migration from upstream blade rows, shocks, tip leakage jets, and vortices interact together as the flow convects through the stages. These interactions contribute significantly to the aerodynamic losses of the system and degrade the performance of the machine. The unsteadiness also leads to blade vibration and a shortening of its life. It is therefore difficult to optimize the design of a blade row, whether aerodynamically or structurally, in isolation, without accounting for the effects of the upstream and downstream rows. The effects of axial spacing, blade count, clocking (relative position of follow-up rotors with respect to wakes shed by upstream ones), and levels of unsteadiness may have a significance on performance and durability. In this Thesis, finite element formulations for the simulation of multistage turbomachinery are presented in terms of the Reynolds-averaged Navier-Stokes equations for three-dimensional steady or unsteady, viscous, compressible, turbulent flows. Three methodologies are presented and compared. First, a steady multistage analysis using a a-mixing- plane model has been implemented and has been validated against engine data. For axial machines, it has been found that the mixing plane simulation methods match very well the experimental data. However, the results for a centrifugal stage, consisting of an impeller followed by a vane diffuser of equal pitch, show flagrant inconsistency with engine performance data, indicating that the mixing plane method has been found to be inappropriate for centrifugal machines. Following these findings, a more complete unsteady multistage model has been devised for a configuration with equal number of rotor and stator blades (equal pitches). Non-matching grids are used at the rotor-stator interface and an implicit interpolation procedure devised to ensure continuity of fluxes across. This permits the rotor and stator equations to be solved in a fully- coupled manner, allowing larger time steps in attaining a time-periodic solution. This equal pitch approach has been validated on the complex geometry of a centrifugal stage. Finally, for a stage configuration with unequal pitches, the time-inclined method, developed by Giles (1991) for 2-D viscous compressible flow, has been extended to 3-D and formulated in terms of the physical solution vector U, rather than Q, a non-physical one. The method has been evaluated for unsteady flow through a rotor blade passage of the power turbine of a turboprop.

Sleiman, Mohamad

1999-11-01

306

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

NASA Astrophysics Data System (ADS)

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 a fixed wound coil on the pump case. The rotation of the rotor creates a continuous flow of liquid through the pump, with a pressure head, and an electrical power is generated in the wound coil because of the rotating magnetic field. The maximum flow rate and pressure are 5000 ml min-1 and 16 kPa, respectively, at 100 Hz. These results meet the requirements of an artificial heart assistance blood pump. Under these operating conditions, the harvested voltage can reach a maximum of 8.2 Vp-p. With this configuration and control method, wireless and battery-free operation is possible, which is required in the medical field. Moreover, the power harvester can monitor the pump conditions without additional electrical power and can provide electrical power to other implanted electrical devices. The performances of the pump and power harvester were verified in a laboratory experiment. Overall, the proposed system acts as a pump and a power harvester that is fully wireless and battery-free.

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

2011-03-01

307

Whole blood pumping with a microthrottle pump  

PubMed Central

We have previously reported that microthrottle pumps (MTPs) display the capacity to pump solid phase suspensions such as polystyrene beads which prove challenging to most microfluidic pumps. In this paper we report employing a linear microthrottle pump (LMTP) to pump whole, undiluted, anticoagulated, human venous blood at 200 ?l min?1 with minimal erythrocyte lysis and no observed pump blockage. LMTPs are particularly well suited to particle suspension transport by virtue of their relatively unimpeded internal flow-path. Micropumping of whole blood represents a rigorous real-world test of cell suspension transport given blood’s high cell content by volume and erythrocytes’ relative fragility. A modification of the standard Drabkin method and its validation to spectrophotometrically quantify low levels of erythrocyte lysis by hemoglobin release is also reported. Erythrocyte lysis rates resulting from transport via LMTP are determined to be below one cell in 500 at a pumping rate of 102 ?l min?1. PMID:21264059

Davies, M. J.; Johnston, I. D.; Tan, C. K. L.; Tracey, M. C.

2010-01-01

308

Multiple pump housing  

DOEpatents

A fluid delivery system includes a first pump having a first drive assembly, a second pump having a second drive assembly, and a pump housing. At least a portion of each of the first and second pumps are located in the housing.

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

2010-03-23

309

Sensorless pump operation estimation  

Microsoft Academic Search

Pumps are widely used in industrial applications, and they account for nearly a quarter of the electric energy consumption in the European industry. Pumps are often overdimensioned or they may be driven inefficiently, which causes unnecessary energy costs. If the pump drive is not equipped with appropriate measurements, inefficient pump operation may remain undetected for years and lead to a

Tero Ahonen; Jussi Tamminen; Jero Ahola; Juha Kestilä

2009-01-01

310

Pumped water storage  

Microsoft Academic Search

The history, current state of development and future developments of electrical energy storage through the pumping of water to a higher elevation are reviewed. Developments in the turbine and pump units of pumped water energy storage plants since their introduction in the 1890s are surveyed, and it is pointed out that the advantages of reversible pump-generator machines have led to

V. G. Newman

1979-01-01

311

Simultaneous viscous-inviscid coupling via transpiration  

SciTech Connect

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

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

1995-09-01

312

Asthenospheric Mantle Flow by Viscous Fingering Instabilities  

NASA Astrophysics Data System (ADS)

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

Weeraratne, D. S.; Parmentier, E.

2010-12-01

313

Inverse transonic airfoil design including viscous interaction  

NASA Technical Reports Server (NTRS)

A numerical technique was developed for the analysis of specified transonic airfoils or for the design of airfoils having a prescribed pressure distribution, including the effect of weak viscous interaction. The method uses the full potential equation, a stretched Cartesian coordinate system, and the Nash-MacDonald turbulent boundary layer method. Comparisons with experimental data for typical transonic airfoils show excellent agreement. An example shows the application of the method to design a thick aft-cambered airfoil, and the effects of viscous interaction on its performance are discussed.

Carlson, L. A.

1976-01-01

314

Open-Source Syringe Pump Library  

PubMed Central

This article explores a new open-source method for developing and manufacturing high-quality scientific equipment suitable for use in virtually any laboratory. A syringe pump was designed using freely available open-source computer aided design (CAD) software and manufactured using an open-source RepRap 3-D printer and readily available parts. The design, bill of materials and assembly instructions are globally available to anyone wishing to use them. Details are provided covering the use of the CAD software and the RepRap 3-D printer. The use of an open-source Rasberry Pi computer as a wireless control device is also illustrated. Performance of the syringe pump was assessed and the methods used for assessment are detailed. The cost of the entire system, including the controller and web-based control interface, is on the order of 5% or less than one would expect to pay for a commercial syringe pump having similar performance. The design should suit the needs of a given research activity requiring a syringe pump including carefully controlled dosing of reagents, pharmaceuticals, and delivery of viscous 3-D printer media among other applications. PMID:25229451

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

2014-01-01

315

Flow measurements in a model centrifugal pump by 3-D PIV  

NASA Astrophysics Data System (ADS)

PIV (Particle Image Velocimetry), as an non-intrusive flow measurements technology, is widely used to investigate the flow fields in many areas. 3-D (three Dimensional) PIV has seldom been used to measure flow field in rotational impeller of centrifugal pump due to the difficulty of calibration in samll space. In this article, a specially manufactured water tank was used to perform the calibration for 3-D PIV measurement. The instantaneous absolute velocity in one impeller passage was obtained by merging of three sub zones and the relative velocity was acquired by velocity decomposition. The result shows that, when the pump runs at the condition of design flow rate, the radial component velocity Wr appears a concave distribution except the condition of R=45 mm. With the increase of radius, the circumference location of the minimum radial component velocity Wr moves from the pressure side to the suction side. At the same time, the tangential component velocity W? on the suction side decreases gradually with the increase of radius, while the component on the pressure side increases gradually. The secondary flow in different radius section has also been shown. At last, the error of PIV measurements was analyzed, which shows that the test results are accurate and the measured data is reliable.

Yang, H.; Xu, H. R.; Liu, C.

2012-11-01

316

Numerical simulation of cavitation effects influenced by centrifugal pump inlet parameters  

NASA Astrophysics Data System (ADS)

Cavitation has great influence on performance of the centrifugal pump. However, there is still no effective design to overcome this problem. Blade leading edge of centrifugal pump impeller is the initial position of cavitation. The leading edge geometry shape not only has a great influence on the cavitation inception and its development, but also a great influence on the flow state near the impeller inlet. In this paper, the numerical simulation method is adopted. Cavitation of four different models (including rectangular-shape blade model, circular-arc-shape blade model, elliptical-shape blade model and cusp-shape blade model) are simulated under the same condition by changing the NPSHA value. The influence of different blade models on cavitation performance is analyzed. The results show that the deviation between the simulated data and experimental data is within the deviation range. The head of rectangular-shape blade model and circular-arc-shape blade model are higher than those of elliptical-shape blade model and cusp-shape blade model. However, the head of rectangular-shape blade model and circular-arc-shape blade model is smaller than the latter under the low effective cavitation margin. What's more, the head of the models with trimmed blade are higher than the head of the models with untrimmed blade under the working condition but are smaller under the low effective cavitation margin.

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

2015-01-01

317

Influence of a new axial impeller on K(L)a and xylanase production by Penicillium canescens 10-10c.  

PubMed

The effects of a new axial impeller (HTPG4) on oxygen volumetric transfer coefficient, K(L)a, and xylanase production by Penicillium canescens 10-10c were studied and compared for dual-impeller systems, one with one DT4 impeller below and one HTPG4 above (DT4-HTPG4) and one with two DT4 (DT4-DT4) impellers, in a 5-L bioreactor. The volumetric coefficient of oxygen transfer was measured in culture medium using a gassing-out method at different gassing rates and agitation speeds. We observed that the DT4-HTPG4 combination provided better K(L)a performance than the DT4-DT4 combination. The two combinations were also tested for their influence on xylanase production by a filamentous microorganism; P. canescens 10-10c. These experiments demonstrated that the DT4-HTPG4 combination impeller enhanced enzyme production up to 23% compared with the DT4-DT4 combination at an aeration rate of 1 vvm and an agitation speed of 600 rpm. The main cause for this difference is thought to be a higher shear stress generated by the DT4-DT4 combination, which damages the mycelium of P. canescens and decreases xylanase production. PMID:12018228

Bakri, Yasser; Jacques, Philippe; Shi, Lin Kui; Thonart, Philippe

2002-01-01

318

Effect of impeller type and stirring frequency on the behavior of an AnSBBR in the treatment of low-strength wastewater.  

PubMed

The influence of impeller type and stirring frequency on the performance of a mechanically stirred anaerobic sequencing batch reactor containing immobilized biomass on an inert support (AnSBBR--Anaerobic Sequencing Batch Biofilm Reactor) was evaluated. The biomass was immobilized on polyurethane foam cubes placed in a stainless-steel basket inside a glass cylinder. Each 8-h batch run consisted of three stages: feed (10 min), reaction (460 min) and discharge (10 min) at 30 °C. Experiments were performed with four impeller types, i.e., helical, flat-blade, inclined-blade and curved-blade turbines, at stirring frequencies ranging from 100 to 1100 rpm. Synthetic wastewater was used in all experiments with an organic-matter concentration of 530±37 mg/L measured as chemical oxygen demand (COD). The reactor achieved an organic-matter removal efficiency of around 87% under all investigated conditions. Analysis of the four impeller types and the investigated stirring frequencies showed that mass transfer in the liquid phase was affected not only by the applied stirring frequency but also by the agitation mode imposed by each impeller type. The best reactor performance at all stirring frequencies was obtained when agitation was provided by the flat-blade turbine impeller. PMID:20888757

Cubas, Selma A; Foresti, Eugenio; Rodrigues, José Alberto D; Ratusznei, Suzana M; Zaiat, Marcelo

2011-01-01

319

The PediPump: a versatile, implantable pediatric ventricular assist device-update III.  

PubMed

The PediPump is a passive magnetic bearing, mixed flow, rotary ventricular assist device designed to provide support for the entire range of patient sizes encountered in pediatrics. Blood enters axially at the inlet and is accelerated and turned in the impeller to exit the pump at an intermediate angle. The size of the PediPump facilitates standard cannulation strategies with substantially downsized components. The program pursues three specific objectives: 1) System engineering: Progress within the last year has focused on the assembly and testing of PediPump prototypes. Initial in vitro hydraulic performance and hemolysis testing were judged satisfactory. 2) Anatomic fitting studies: As part of the PediPump program, three-dimensional modeling techniques based on routine, clinically obtained computerized tomography (CT) scans have been developed. During 2006, the same techniques developed for clinical scans were applied to CT scans obtained from sheep to guide the presurgical planning. 3) Animal studies: Animal implantation of PediPump prototypes commenced in July 2006. A total of four 6 hour acute studies were performed throughout the remainder of the year. In vivo performance was satisfactory and compared well with the in vitro results. Hemolysis levels were low. PMID:18043157

Weber, Stephan; Dudzinski, David T; Gu, Lei; Mielke, Nicole; Casas, Fernando; Noecker, Angela M; Saeed, Diyar; Ootaki, Yoshio; Fukamachi, Kiyotaka; Smith, William A; Duncan, Brian W

2007-01-01

320

Development of a Compact Efficient Cooling Pump for Space Suit Life Support Systems  

NASA Technical Reports Server (NTRS)

With the increasing demands placed on extravehicular activity (EVA) for the International Space Station (ISS) assembly and maintenance, along with planned lunar and Martian missions, the need for increased human productivity and capability becomes ever more critical. This is most readily achieved by reduction in space suit weight and volume, and increased hardware reliability, durability, and operating lifetime. Considerable progress has been made with each successive generation of space suit design; from the Apollo A7L suit, to the current Shuttle Extravehicular Mobile Unit (EMU) suit, and the next generation Constellation Space Suit Element (CSSE). However, one area of space suit design which has continued to lag is the fluid pump used to drive the water cooling loop of the Primary Life Support System (PLSS). The two main types of fluid pumps typically used in space applications are rotodynamic pumps (pumping is achieved through a rotary vaned impeller) and displacement pumps (which includes rotary and diaphragm pumps). The rotating and moving parts found in the pumps and electric motor add significantly to the susceptibility to wear and friction, thermal mismatch, and complexity of the pumps. Electric motor-driven pumps capable of achieving high operational reliability are necessarily large, heavy, and energy inefficient. This report describes a development effort conducted for NASA by Lynntech, Inc., who recently demonstrated the feasibility of an electrochemically-driven fluid cooling pump. With no electric motor and minimal lightweight components, an electrochemically-driven pump is expected to be significantly smaller, lighter and achieve a longer life time than conventional rotodynamic and displacement pumps. By employing sulfonated polystyrene-based proton exchange membranes, rather than conventional Nafion membranes, a significant reduction in the actuator power consumption was demonstrated. It was also demonstrated that these membranes possess the necessary mechanical strength, durability, and temperature range for long life space operation. The preliminary design for a Phase II prototype pump compares very favorably to the fluid cooling pumps currently used in space suit portable life support systems (PLSS). Characteristics of the electrochemically-driven pump are described and the benefits of the technology as a replacement for electric motor pumps in mechanically pumped single-phase fluid loops (MPFLs) is discussed.

vanBoeyen, Roger W.; Reeh, Jonathan A.; Trevino, Luis

2008-01-01

321

Disposable magnetically levitated centrifugal blood pump: design and in vitro performance.  

PubMed

A magnetically levitated (MagLev) centrifugal blood pump (CBP) with a disposable pump head has been designed to realize a safe, easy-to-handle, reliable, and low-cost extracorporeal blood pump system. It consisted of a radial magnetic-coupled driver with a magnetic bearing having a two-degree freedom control and a disposable pump head unit with a priming volume of 24 mL. The easy on-off disposable pump head unit was made into a three-piece system consisting of the top and bottom housings, and the impeller-rotor assembly. The size and weight of the disposable pump unit were 75 mm x 45 mm and 100 g, respectively. Because the structure of the pump head unit is easily attachable and removable, the gap between the electromagnets of the stator and the target material in the rotor increased to 1.8 mm in comparison to the original integrated bearing system of 1.0 mm. The pump performance, power requirements, and controllability of the magnetic bearing revealed that from 1400 to 2400 rpm, the pump performance remained fairly unchanged. The amplitudes of the X- and Y-axis rotor oscillation increased to +/- 24 microm. The axial displacement of the rotor, 0.4 mm, toward the top housing was also observed at the pump rpm between 1400 and 2400. The axial and rotational stiffness of the bearing were 15.9 N/mm and 4.4 Nm/rad, respectively. The MagLev power was within 0.7 Watts. This study demonstrated the feasibility of a disposable, magnetically suspended CBP as the safe, reliable, easy-to-handle, low-cost extracorporeal circulation support device. PMID:15982279

Hoshi, Hideo; Asama, Junichi; Shinshi, Tadahiko; Ohuchi, Katsuhiro; Nakamura, Makoto; Mizuno, Tomohiro; Arai, Hirokuni; Shimokohbe, Akira; Takatani, Setsuo

2005-07-01

322

Viscous Driven-Cavity Solver: User's Manual  

NASA Technical Reports Server (NTRS)

The viscous driven-cavity problem is solved using a stream-function and vorticity formulation for the incompressible Navier-Stokes equations. This report provides the user's manual and FORTRAN code for the set of governing equations presented in NASA TM-110262.

Wood, William A.

1997-01-01

323

Some basic viscous flows in micropolar fluids  

Microsoft Academic Search

Summary This paper analyzes some basic viscous flows of micropolar fluids. The problems ofCouette andPoiseuille flows between two parallel plates and a rotating fluid with a free surface, are solved using the theory of micropolar fluids. The results are presented graphically and compared with the classical ones, and the differences are discussed.

Teoman Ariman; Ahmet S. Cakmak

1968-01-01

324

Dilepton production in schematic causal viscous hydrodynamics  

SciTech Connect

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

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

2011-02-15

325

Dilepton production from a viscous QGP  

Microsoft Academic Search

This work calculates the first correction to the leading order qqŻ 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

326

Injection Well Logging Using Viscous EOR Fluids  

Microsoft Academic Search

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

Bruce Knight; Mohammad Davarzani

1986-01-01

327

Viscous Dark Energy and Generalized Second Law of Thermodynamics  

Microsoft Academic Search

We examine the validity of the generalized second law of thermodynamics in a non-flat universe in the presence of viscous dark energy. First we assume that the universe is filled only with viscous dark energy. Then, we extend our study to the case where there is an interaction between viscous dark energy and pressureless dark matter. We examine the time

M. R. Setare; A. Sheykhi

2010-01-01

328

Dry actuation testing of viscous drag micropumping systems for determination of optimal drive waveforms  

NASA Astrophysics Data System (ADS)

This paper presents the dry actuation testing procedures and results for novel viscous drag micropumping systems. To overcome the limitations of previously developed mechanical pumps, we have developed pumps that are surface micromachined for efficient mass production which utilize viscous drag (dominant at low Reynolds numbers typical of microfluidics) to move fluid. The SUMMiT (www.sandia.gov/micromachine) fabricated pumps, presented first by Kilani et al., are being experimentally and computationally analyzed. In this paper we will describe the development of optimal waveforms to drive the electrostatic pumping mechanism while dry. While wet actuation will be significantly different, dry testing provides insight into how to optimally move the mechanism and differences between dry and wet actuation can be used to isolate fluid effects. Characterization began with an analysis of the driving voltage waveforms for the torsional ratcheting actuator (TRA), a micro-motor that drove the gear transmission for the pump, actuated with SAMA (Sandia"s Arbitrary waveform MEMS Actuator), a new waveform generating computer program with the ability to generate and output arbitrary voltage signals. Based upon previous research, a 50% duty cycle half-sine wave was initially selected for actuation of the TRA. However, due to the geometry of the half-sine waveform, the loaded micromotor could not transmit the motion required to pump the tested liquids. Six waveforms were then conceived, constructed, and selected for device actuation testing. Dry actuation tests included high voltage, low voltage, high frequency, and endurance/reliability testing of the TRA, gear transmission and pump assembly. In the SUMMiT process, all of the components of the system are fabricated together on one silicon chip already assembled in a monolithic microfabrication process. A 40% duty cycle quarter-sine waveform with a 20% DC at 60V has currently proved to be the most reliable, allowing for an 825Hz continuous TRA operating frequency for the micropumps. This novel waveform allowed for higher TRA actuation frequencies than those obtained in prior research of the pumps.

Sosnowchik, Brian D.; Galambos, Paul C.; Sharp, Kendra V.; Jenkins, Mark W.; Horn, Mark W.; Hendrix, Jason R.

2003-12-01

329

Numerical simulation and analysis of power consumption and Metzner-Otto constant for impeller of 6PBT  

NASA Astrophysics Data System (ADS)

Majority of non-Newtonian fluids are pseudoplastic with shear-thinning property, which means that the viscosity will be different in different parts of the stirred tank. In such mixing process, it is difficult to predict accurately the power consumption and mean shear rate for designing novel impeller. Metzner-Otto method is a widely accepted method to solve these questions in mixing non-Newtonian fluids. As a result, Metzner-Otto constant will become a key factor to achieve an optimum way of economical mixing. In this paper, taking glycerine and xanthan gum solutions as research system, the power consumption, stirred by the impeller composed of perturbed six-bent-bladed turbine (6PBT) with differently geometrical characteristics in a cylindrical vessel, is studied by means of computational fluid dynamics (CFD). The flow is modeled as laminar and a multiple reference frame (MRF) approach is used to solve the discretized equations of motion. In order to determine the capability of CFD to forecast the flow process, the torque test experiment is used to measure the glycerine solution power consumption. The rheological properties of the xanthan gum solutions are determined by a Brookfield rheometer. It is observed that the power consumption predicted by numerical simulation agrees well with those measured using torque experiment method in stirring glycerine solution, which validate the numerical model. Metzner-Otto constant is almost not correlated with the flow behavior index of pseudoplastic fluids. This paper establishes the complete correlations of power constant and Metzner-Otto constant with impeller geometrical characteristics through linear regression analysis, which provides the valuable instructions and references for accurately predicting the power consumption and mean shear rate of pseudoplastic fluids in laminar flow, comparatively.

Luan, Deyu; Chen, Qiao; Zhou, Shenjie

2014-05-01

330

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

SciTech Connect

As part of the U.S. ITER contribution to the vacuum systems for the ITER fusion project, a cryogenic viscous compressor (CVC) is being designed and fabricated to cryopump hydrogenic gases in the torus and neutral beam exhaust streams and to regenerate the collected gases to controlled pressures such that they can be mechanically pumped with controlled flows to the tritium reprocessing facility. One critical element of the CVC design that required additional investigation was the determination of flow rates of the low pressure (up to 1000 Pa) exhaust stream that would allow for complete pumping of hydrogenic gases while permitting trace levels of helium to pass through the CVC to be pumped by conventional vacuum pumps. A sub-scale prototype test facility was utilized to determine the effectiveness of a static mixer pump tube concept, which consisted of a series of rotated twisted elements brazed into a 2-mm thick, 5-cm diameter stainless steel tube. Cold helium gas flow provided by a dewar and helium transfer line was used to cool the exterior of the static mixer pump tube. Deuterium gas was mixed with helium gas through flow controllers at different concentrations while the composition of the exhaust gas was monitored with a Penning gauge and optical spectrometer to determine the effectiveness of the static mixer. It was found that with tube wall temperatures between 6 K and 9 K, the deuterium gas was completely cryopumped and only helium passed through the tube. These results have been used to design the cooling geometry and the static mixer pump tubes in the full-scale CVC prototype.

Duckworth, Robert C.; Baylor, Larry R.; Meitner, Steven J.; Combs, Stephen K.; Ha, Tam; Morrow, Michael; Biewer, T. [Fusion and Materials for Nuclear System Division, Oak Ridge National Laboratory, Oak Ridge (United States); Rasmussen, David A.; Hechler, Michael P. [U.S. ITER Project Office, Oak Ridge National Laboratory, Oak Ridge (United States); Pearce, Robert J. H.; Dremel, Mattias [ITER Organization, 13115 St. Paul-lez-Durance (France); Boissin, J.-C. [Consultant, Grenoble (France)

2014-01-29

331

Insulin pump (image)  

MedlinePLUS

The catheter at the end of the insulin pump is inserted through a needle into the abdominal ... with diabetes. Dosage instructions are entered into the pump's small computer and the appropriate amount of insulin ...

332

Proton pump inhibitors  

MedlinePLUS

Proton pump inhibitors (PPIs) are medicines that work by reducing the amount of stomach acid made by glands in ... Proton pump inhibitors are used to: Relieve symptoms of acid reflux, or gastroesophageal reflux disease (GERD). This is a ...

333

Rotary Piston Pump  

NSDL National Science Digital Library

The animation of a rotary piston pump. This describes the rotary piston pump operation. This simulation is from Module 99 of the Vacuum Technology and Gas Control Cluster of the MATEC Module Library (MML).

334

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

NASA Astrophysics Data System (ADS)

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

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

2012-11-01

335

Rotary magnetic heat pump  

DOEpatents

A rotary magnetic heat pump constructed without flow seals or segmented rotor accomplishes recuperation and regeneration by using split flow paths. Heat exchange fluid pumped through heat exchangers and returned to the heat pump splits into two flow components: one flowing counter to the rotor rotation and one flowing with the rotation. 5 figs.

Kirol, L.D.

1987-02-11

336

Lightweight, Switchable Peristaltic Pump  

NASA Technical Reports Server (NTRS)

Peristaltic pump moves liquids through 50 or more channels simultaneously. Special feature of pump pressure plates remotely set between idle and operating positions. In new design, unnecessary to preposition pressure plates and, unnecessary to enter pump housing to move plates into operating mode.

Below, R. R.

1986-01-01

337

Rotary magnetic heat pump  

DOEpatents

A rotary magnetic heat pump constructed without flow seals or segmented rotor accomplishes recuperation and regeneration by using split flow paths. Heat exchange fluid pumped through heat exchangers and returned to the heat pump splits into two flow components: one flowing counter to the rotor rotation and one flowing with the rotation.

Kirol, Lance D. (Shelly, ID)

1988-01-01

338

Water Treatment Technology - Pumps.  

ERIC Educational Resources Information Center

One of twelve water treatment technology units, this student manual on pumps provides instructional materials for three competencies. (The twelve units are designed for a continuing education training course for public water supply operators.) The competencies focus on the following areas: types of pumps in plant and distribution systems, pump

Ross-Harrington, Melinda; Kincaid, G. David

339

Physical Modeling of Fluid Flow in Ladles of Aluminum Equipped with Impeller and Gas Purging For Degassing  

NASA Astrophysics Data System (ADS)

In the current study a transparent water physical model was developed to study fluid flow and turbulent structure of aluminum ladles for degassing treatment with a rotating impeller and gas injection. Flow patterns and turbulent structure in the ladle were measured with the particle image velocimetry technique. The effects of process parameters such as rotor speed, gas flow rate, and type of rotor on the flow patterns and on the vortex formation were analyzed using this model, which control degassing kinetics. In addition, a comparison between two points of gas injection was performed: (a) conventional gas injection through the shaft and (b) a "novel" gas injection technique through the bottom of the ladle. Results show that the most significant process variable on the stirring degree of the bath was the angular speed of the impeller, which promotes better stirred baths with smaller and better distributed bubbles. A gas flow rate increment is detrimental to stirring. Finally, although the injection point was the less-significant variable, it was found that the "novel" injection from the bottom of the ladle improves the stirring in the ladle, promotes a better distribution of bubbles, and shows to be a promising alternative for gas injection.

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

2013-08-01

340

Bulk viscous cosmology with causal transport theory  

SciTech Connect

We consider cosmological scenarios originating from a single imperfect fluid with bulk viscosity and apply Eckart's and both the full and the truncated Müller-Israel-Stewart's theories as descriptions of the non-equilibrium processes. Our principal objective is to investigate if the dynamical properties of Dark Matter and Dark Energy can be described by a single viscous fluid and how such description changes when a causal theory (Müller-Israel-Stewart's, both in its full and truncated forms) is taken into account instead of Eckart's non-causal one. To this purpose, we find numerical solutions for the gravitational potential and compare its behaviour with the corresponding ?CDM case. Eckart's and the full causal theory seem to be disfavoured, whereas the truncated theory leads to results similar to those of the ?CDM model for a bulk viscous speed in the interval 10{sup ?11} || cb{sup 2} ?< 10{sup ?8}.

Piattella, Oliver F.; Fabris, Júlio C.; Zimdahl, Winfried, E-mail: oliver.piattella@gmail.com, E-mail: fabris@pq.cnpq.br, E-mail: winfried.zimdahl@pq.cnpq.br [Departamento de Física, Universidade Federal do Espírito Santo, Avenida Ferrari 514, 29075-910 Vitória, Espírito Santo (Brazil)

2011-05-01

341

High order accurate solutions of viscous problems  

NASA Technical Reports Server (NTRS)

We consider a fourth order extension to MacCormack's scheme. The original extension was fourth order only for the inviscid terms but was second order for the viscous terms. We show how to modify the viscous terms so that the scheme is uniformly fourth order in the spatial derivatives. Applications are given to some boundary layer flows. In addition, for applications to shear flows the effect of the outflow boundary conditions are very important. We compare the accuracy of several of these different boundary conditions for both boundary layer and shear flows. Stretching at the outflow usually increases the oscillations in the numerical solution but the addition of a filtered sponge layer (with or without stretching) reduces such oscillations. The oscillations are generated by insufficient resolution of the shear layer. When the shear layer is sufficiently resolved then oscillations are not generated and there is less of a need for a nonreflecting boundary condition.

Hayder, M. Ehtesham; Turkel, Eli

1993-01-01

342

A viscous-inviscid interactive compressor calculations  

NASA Technical Reports Server (NTRS)

A viscous-inviscid interactive procedure for subsonic flow is developed and applied to an axial compressor stage. Calculations are carried out on a two-dimensional blade-to-blade region of constant radius assumed to occupy a mid-span location. Hub and tip effects are neglected. The Euler equations are solved by MacCormack's method, a viscous marching procedure is used in the boundary layers and wake, and an iterative interaction scheme is constructed that matches them in a way that incorporates information related to momentum and enthalpy thicknesses as well as the displacement thickness. The calculations are quasi-three-dimensional in the sense that the boundary layer and wake solutions allow for the presence of spanwise (radial) velocities.

Johnston, W.; Sockol, P. M.

1978-01-01

343

Viscous damping of perforated planar micromechanical structures  

PubMed Central

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

Homentcovschi, D.; Miles, R.N.

2008-01-01

344

Feasibility of the optical imaging of thrombus formation in a rotary blood pump by near-infrared light.  

PubMed

Blood coagulation is one of the primary concerns when using mechanical circulatory support devices such as blood pumps. Noninvasive detection and imaging of thrombus formation is useful not only for the development of more hemocompatible devices but also for the management of blood coagulation to avoid risk of infarction. The objective of this study is to investigate the use of near-infrared light for imaging of thrombus formation in a rotary blood pump. The optical properties of a thrombus at wavelengths ranging from 600 to 750?nm were analyzed using a hyperspectral imaging (HSI) system. A specially designed hydrodynamically levitated centrifugal blood pump with a visible bottom area was used. In vitro antithrombogenic testing was conducted five times with the pump using bovine whole blood in which the activated blood clotting time was adjusted to 200?s prior to the experiment. Two halogen lights were used for the light sources. The forward scattering through the pump and backward scattering on the pump bottom area were imaged using the HSI system. HSI showed an increase in forward scattering at wavelengths ranging from 670 to 750?nm in the location of thrombus formation. The time at which the thrombus began to form in the impeller rotating at 2780?rpm could be detected. The spectral difference between the whole blood and the thrombus was utilized to image thrombus formation. The results indicate the feasibility of dynamically detecting and imaging thrombus formation in a rotary blood pump. PMID:25234757

Sakota, Daisuke; Murashige, Tomotaka; Kosaka, Ryo; Nishida, Masahiro; Maruyama, Osamu

2014-09-01

345

Vortex Motion in a Viscous Fluid  

Microsoft Academic Search

A discussion is given of a three-dimensional vortex in a viscous fluid. A theory is outlined that leads to a reduction of the steady-state Navier-Stokes equations of an incompressible fluid to three ordinary, nonlinear, differential equations. Although no numerical results are available, qualitative arguments based on these equations and on the form of their dependent and independent variables throw considerable

Robert R. Long

1958-01-01

346

Dynamics of vortex rings in viscous fluids  

NASA Astrophysics Data System (ADS)

As part of a long range study of vortex rings, their dynamics, interactions with boundaries and with each other, we present the results of experiments on thin core rings generated by a piston gun in water. We characterize the dynamics of these rings by means of the traditional equations for such rings in an inviscid fluid suitably modifying them to be applicable to a viscous fluid. We develop expressions for the radius, core size, circulation, and bubble dimensions of these rings.

Donnelly, Russell J.

2010-03-01

347

Jet pump assisted artery  

NASA Technical Reports Server (NTRS)

A procedure for priming an arterial heat pump is reported; the procedure also has a means for maintaining the pump in a primed state. This concept utilizes a capillary driven jet pump to create the necessary suction to fill the artery. Basically, the jet pump consists of a venturi or nozzle-diffuser type constriction in the vapor passage. The throat of this venturi is connected to the artery. Thus vapor, gas, liquid, or a combination of the above is pumped continuously out of the artery. As a result, the artery is always filled with liquid and an adequate supply of working fluid is provided to the evaporator of the heat pipe.

1975-01-01

348

Liquid metal electric pump  

DOEpatents

An electrical pump for pumping liquid metals to high pressures in high temperature environments without the use of magnets or moving mechanical parts. The pump employs a non-porous solid electrolyte membrane, typically ceramic, specific to the liquid metal to be pumped. A DC voltage is applied across the thickness of the membrane causing ions to form and enter the membrane on the electrically positive surface, with the ions being neutralized on the opposite surface. This action provides pumping of the liquid metal from one side of the non-porous solid electrolyte membrane to the other.

Abbin, Joseph P. (Albuquerque, NM); Andraka, Charles E. (Albuquerque, NM); Lukens, Laurance L. (Albuquerque, NM); Moreno, James B. (Albuquerque, NM)

1992-01-01

349

Liquid metal electric pump  

DOEpatents

An electrical pump for pumping liquid metals to high pressures in high temperature environments without the use of magnets or moving mechanical parts. The pump employs a non-porous solid electrolyte membrane, typically ceramic, specific to the liquid metal to be pumped. A DC voltage is applied across the thickness of the membrane causing ions to form and enter the membrane on the electrically positive surface, with the ions being neutralized on the opposite surface. This action provides pumping of the liquid metal from one side of the non-porous solid electrolyte membrane to the other. 3 figs.

Abbin, J.P.; Andraka, C.E.; Lukens, L.L.; Moreno, J.B.

1992-01-14

350

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

351

Computation of viscous blast wave flowfields  

NASA Technical Reports Server (NTRS)

A method to determine unsteady solutions of the Navier-Stokes equations was developed and applied. The structural finite-volume, approximately factored implicit scheme uses Newton subiterations to obtain the spatially and temporally second-order accurate time history of the interaction of blast-waves with stationary targets. The inviscid flux is evaluated using MacCormack's modified Steger-Warming flux or Roe flux difference splittings with total variation diminishing limiters, while the viscous flux is computed using central differences. The use of implicit boundary conditions in conjunction with a telescoping in time and space method permitted solutions to this strongly unsteady class of problems. Comparisons of numerical, analytical, and experimental results were made in two and three dimensions. These comparisons revealed accurate wave speed resolution with nonoscillatory discontinuity capturing. The purpose of this effort was to address the three-dimensional, viscous blast-wave problem. Test cases were undertaken to reveal these methods' weaknesses in three regimes: (1) viscous-dominated flow; (2) complex unsteady flow; and (3) three-dimensional flow. Comparisons of these computations to analytic and experimental results provided initial validation of the resultant code. Addition details on the numerical method and on the validation can be found in the appendix. Presently, the code is capable of single zone computations with selection of any permutation of solid wall or flow-through boundaries.

Atwood, Christopher A.

1991-01-01

352

Nonisothermal viscous sintering of volcanic ash  

NASA Astrophysics Data System (ADS)

ash is often deposited in a hot state. Volcanic ash containing glass, deposited above the glass transition interval, has the potential to sinter viscously both to itself (particle-particle) and to exposed surfaces. Here we constrain the kinetics of this process experimentally under nonisothermal conditions using standard glasses. In the absence of external load, this process is dominantly driven by surface relaxation. In such cases the sintering process is rate limited by the melt viscosity, the size of the particles and the melt-vapor interfacial tension. We propose a polydisperse continuum model that describes the transition from a packing of particles to a dense pore-free melt and evaluate its efficacy in describing the kinetics of volcanic viscous sintering. We apply our model to viscous sintering scenarios for cooling crystal-poor rhyolitic ash using the 2008 eruption of Chaitén volcano as a case example. We predict that moderate linear cooling rates of > 0.1°C min-1 can result in the common observation of incomplete sintering and the preservation of pore networks.

Wadsworth, Fabian B.; Vasseur, Jérémie; Aulock, Felix W.; Hess, Kai-Uwe; Scheu, Bettina; Lavallée, Yan; Dingwell, Donald B.

2014-12-01

353

Experimental testing of centrifugal pump: small and medium sized enterprise product  

NASA Astrophysics Data System (ADS)

This paper reports the experimental testing for centrifugal pump for fisherman ship, manufactured by small and medium sized enterprises in Central Java Province, Indonesia. The research covers material analysis, component observation, endurance and vibration test. Six centrifugal pumps are tested and three main pump components are discussed: shaft, bearings and seals. The results show that the material of the shaft is predicted to support and transmit the load from the engine to impeller. The problem found in the tolerance and geometry accuracy of the shaft which causes difficulties during assembling process, excessive wear and leakage during testing. From the endurance and vibration test, the ball bearings fail and lock the shaft due to the fatigue on the rolling elements and raceways. The oil seal and water seal also fail in maintaining the oil and water in the chamber and induce the unlubricated system for the ball bearings. Some suggestions are delivered to improve the product quality of the centrifugal pump. A good quality of the centrifugal pump for fishermen ship and long life span is expected to be produced by local SMEs to win the free trade competition in the Indonesian market.

Ismail, R.; Paddiyatu, F.; Khafidh, M.; Nugroho, S.; Sugiyanto, S.; Jamari, J.

2014-06-01

354

The PediPump: a versatile, implantable pediatric ventricular assist device--update IV.  

PubMed

Cleveland Clinic's PediPump (Cleveland, OH, USA) is a ventricular assist device designed for the support of pediatric patients. The PediPump is a mixed-flow ventricular assist device with a magnetically suspended impeller measuring 10.5 mm in diameter by 64.5 mm in length. Progress and achievements for the PediPump program are considered according to the development project's three primary objectives: Basic engineering: along with size reductions, substantial design improvements have been incorporated in each design iteration including the motor, magnetic bearings, axial touch points, and heat transfer path; Anatomic modeling and device fitting studies: Techniques based on computed tomography and magnetic resonance imaging have been developed to create three-dimensional anatomic-modeling and device-fitting tools to facilitate device implantation and to assist in preoperative planning. For in vivo testing, to date, six acute (6-h duration) and nine chronic (30-day target duration) implantations have been performed in sheep; the implantation of the PediPump appears to be relatively easy with excellent hemodynamic performance and minimal hemolysis during support. Cleveland Clinic's PediPump program supported by the National Heart, Lung and Blood Institute's Pediatric Circulatory Support Program has led to the development of a pediatric ventricular assist device that has satisfactory performance in preclinical evaluation and appears to be ready to support a program of clinical testing. PMID:20050296

Duncan, Brian W; Fukamachi, Kiyotaka; Noble, Lawrence D; Dudzinski, David T; Flick, Christine R; Fumoto, Hideyuki; Shiose, Akira; Arakawa, Yoko; Takaseya, Tohru; Casas, Fernando; Smith, William A

2009-11-01

355

Hydrodynamic performance enhancement of a mixed-flow pump  

NASA Astrophysics Data System (ADS)

This paper presents an optimization procedure based on a radial basis neural network surrogate model for design of a vaned diffuser in a mixed-flow pump. Numerical analysis of fluid flow in a mixed-flow pump has been carried out by solving three-dimensional Reynolds-averaged Navier-Stokes equations with the shear stress transport turbulence model. The optimization processes have been performed twice to investigate the coupled effects of diverse variables. The first optimization process has been conducted with two design variables defining the straight vane length ratio and the diffusion area ratio, and the second one has been conducted with four design variables, i.e., the angle at the diffuser vane tip, the distance between the impeller blade trailing edge and the diffuser vane leading edge, and the two design variables used in the first optimization. The efficiency as a hydrodynamic performance parameter has been selected as the objective function for optimizations. The objective function values have been assessed through three-dimensional flow analysis at design points sampled by Latin hypercube sampling in the design space. The first and second optimizations with the coupled effects of diverse variables have yielded maximum increases in efficiency of 7.16% and 9.75%, respectively, compared to the reference shape. The off-design performance has been also improved in most of the optimum shapes except in the shut-off flow region.

Kim, J. H.; Kim, K. Y.

2012-11-01

356

Viscous dark energy and generalized second law of thermodynamics  

E-print Network

We examine the validity of the generalized second law of thermodynamics in a non-flat universe in the presence of viscous dark energy. At first we assume that the universe filled only with viscous dark energy. Then, we extend our study to the case where there is an interaction between viscous dark energy and pressureless dark matter. We examine the time evolution of the total entropy, including the entropy associated with the apparent horizon and the entropy of the viscous dark energy inside the apparent horizon. Our study show that the generalized second law of thermodynamics is always protected in a universe filled with interacting viscous dark energy and dark matter in a region enclosed by the apparent horizon. Finally, we show that the the generalized second law of thermodynamics is fulfilled for a universe filled with interacting viscous dark energy and dark matter in the sense that we take into account the Casimir effect.

M. R. Setare; A. Sheykhi

2011-03-05

357

Plane waves in a thermally conducting viscous liquid  

Microsoft Academic Search

The aim of this paper is to investigate plane waves in a thermally conducting viscous liquid half-space with thermal relaxation\\u000a times. There exist three basic waves, namely; thermal wave, longitudinal wave and transverse wave in a thermally conducting\\u000a viscous liquid half-space. Reflection of plane waves from the free surface of a thermally conducting viscous liquid half-space\\u000a is studied. The results

Baljeet Singh

2004-01-01

358

Waveguide sensor for measurement of viscosity of highly viscous fluids  

NASA Astrophysics Data System (ADS)

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

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

2013-11-01

359

Electrokinetic pumps and actuators  

SciTech Connect

Flow and ionic transport in porous media are central to electrokinetic pumping as well as to a host of other microfluidic devices. Electrokinetic pumping provides the ability to create high pressures (to over 10,000 psi) and high flow rates (over 1 mL/min) with a device having no moving parts and all liquid seals. The electrokinetic pump (EKP) is ideally suited for applications ranging from a high pressure integrated pump for chip-scale HPLC to a high flow rate integrated pump for forced liquid convection cooling of high-power electronics. Relations for flow rate and current fluxes in porous media are derived that provide a basis for analysis of complex microfluidic systems as well as for optimization of electrokinetic pumps.

Phillip M. Paul

2000-03-01

360

Piezoelectric hydraulic pump performance  

NASA Astrophysics Data System (ADS)

A piezohydraulic pump making use of the step and repeat capability of piezoelectric actuators has been developed for actuation of aircraft control surfaces. The piezohydraulic pump utilizes a piezoelectric stack actuator to drive a piston in a cylinder. The cylinder is fitted with two check valves. On the compression stroke, oil is forced out of the cylinder. On the intake stroke, oil is drawn into the cylinder. The oil is used to drive a linear actuator. The actuator was driven at 7cm/sec with a 271N (61lb) blocking force. To achieve this, the piezoelectric stack actuator was driven at 60Hz with a switching power supply. The system utilizes an accumulator to eliminate cavitation. This work discusses piezohydraulic pumping theory, pump design, and pump performance. Consideration of pump performance includes the effects of varying accumulator pressure, hydraulic oil viscosity, and load imposed on the linear actuator.

Mauck, Lisa D.; Oates, William S.; Lynch, Christopher S.

2001-06-01

361

Pump isolation valve  

DOEpatents

The pump isolation valve provides a means by which the pump may be selectively isolated from the remainder of the coolant system while being compatible with the internal hydraulic arrangement of the pump during normal operation of the pump. The valve comprises a valve cylinder disposed around the pump and adjacent to the last pump diffuser with a turning vane attached to the lower end of the valve cylinder in a manner so as to hydraulically match with the discharge diffuser. The valve cylinder is connected to a drive means for sliding the valve cylinder relative to the diffuser support cylinder so as to block flow in either direction through the discharge diffuser when the valve is in the closed position and to aid in the flow of the coolant from the discharge diffuser by means of the turning vane when the valve is in the open position.

Kinney, Calvin L. (Penn Hills, PA); Wetherill, Todd M. (Lower Burrell, PA)

1983-08-02

362

Estimation of the radial force using a disturbance force observer for a magnetically levitated centrifugal blood pump.  

PubMed

Evaluation of the hydraulic forces in a magnetically levitated (maglev) centrifugal blood pump is important from the point of view of the magnetic bearing design. Direct measurement is difficult due to the absence of a rotor shaft, and computational fluid dynamic analysis demands considerable computational resource and time. To solve this problem, disturbance force observers were developed, using the radial controlled magnetic bearing of a centrifugal blood pump, to estimate the radial forces on the maglev impeller. In order to design the disturbance observer, the radial dynamic characteristics of a maglev impeller were evaluated under different working conditions. It was observed that the working fluid affects the additional mass and damping, while the rotational speed affects the damping and stiffness of the maglev system. Based on these results, disturbance force observers were designed and implemented. The designed disturbance force observers present a bandwidth of 45 Hz. In non-pulsatile conditions, the magnitude of the estimated radial thrust increases in proportion to the flowrate, and the rotational speed has little effect on the force direction. At 5 l/min against 100 mmHg, the estimated radial thrust is 0.95 N. In pulsatile conditions, this method was capable of estimating the pulsatile radial thrust with good response. PMID:20839658

Pai, C N; Shinshi, T; Shimokohbe, A

2010-01-01

363

Detection of pump degradation  

SciTech Connect

This Phase II Nuclear Plant Aging Research study examines the methods of detecting pump degradation that are currently employed in domestic and overseas nuclear facilities. This report evaluates the criteria mandated by required pump testing at U.S. nuclear power plants and compares them to those features characteristic of state-of-the-art diagnostic programs and practices currently implemented by other major industries. Since the working condition of the pump driver is crucial to pump operability, a brief review of new applications of motor diagnostics is provided that highlights recent developments in this technology. The routine collection and analysis of spectral data is superior to all other technologies in its ability to accurately detect numerous types and causes of pump degradation. Existing ASME Code testing criteria do not require the evaluation of pump vibration spectra but instead overall vibration amplitude. The mechanical information discernible from vibration amplitude analysis is limited, and several cases of pump failure were not detected in their early stages by vibration monitoring. Since spectral analysis can provide a wealth of pertinent information concerning the mechanical condition of rotating machinery, its incorporation into ASME testing criteria could merit a relaxation in the monthly-to-quarterly testing schedules that seek to verify and assure pump operability. Pump drivers are not included in the current battery of testing. Operational problems thought to be caused by pump degradation were found to be the result of motor degradation. Recent advances in nonintrusive monitoring techniques have made motor diagnostics a viable technology for assessing motor operability. Motor current/power analysis can detect rotor bar degradation and ascertain ranges of hydraulically unstable operation for a particular pump and motor set. The concept of using motor current or power fluctuations as an indicator of pump hydraulic load stability is presented.

Greene, R.H.; Casada, D.A.; Ayers, C.W. [and others

1995-08-01

364

Submersible sodium pump  

DOEpatents

An electromagnetic submerged pump has an outer cylindrical stator with an inner cylindrical conductive core for the submerged pumping of sodium in the cylindrical interstitial volume defined between the stator and core. The cylindrical interstitial volume is typically vertically oriented, and defines an inlet at the bottom and an outlet at the top. The outer stator generates upwardly conveyed toroidal magnetic fields, which fields convey preferably from the bottom of the pump to the top of the pump liquid sodium in the cold leg of a sodium cooled nuclear reactor. The outer cylindrical stator has a vertically disposed duct surrounded by alternately stacked layers of coil units and laminates.

Brynsvold, Glen V. (San Jose, CA); Lopez, John T. (Santa Clara, CA); Olich, Eugene E. (Aptos, CA); West, Calvin W. (Livermore, CA)

1989-01-01

365

Champagne Heat Pump  

NASA Technical Reports Server (NTRS)

The term champagne heat pump denotes a developmental heat pump that exploits a cycle of absorption and desorption of carbon dioxide in an alcohol or other organic liquid. Whereas most heat pumps in common use in the United States are energized by mechanical compression, the champagne heat pump is energized by heating. The concept of heat pumps based on other absorption cycles energized by heat has been understood for years, but some of these heat pumps are outlawed in many areas because of the potential hazards posed by leakage of working fluids. For example, in the case of the water/ammonia cycle, there are potential hazards of toxicity and flammability. The organic-liquid/carbon dioxide absorption/desorption cycle of the champagne heat pump is similar to the water/ammonia cycle, but carbon dioxide is nontoxic and environmentally benign, and one can choose an alcohol or other organic liquid that is also relatively nontoxic and environmentally benign. Two candidate nonalcohol organic liquids are isobutyl acetate and amyl acetate. Although alcohols and many other organic liquids are flammable, they present little or no flammability hazard in the champagne heat pump because only the nonflammable carbon dioxide component of the refrigerant mixture is circulated to the evaporator and condenser heat exchangers, which are the only components of the heat pump in direct contact with air in habitable spaces.

Jones, Jack A.

2004-01-01

366

Submersible sodium pump  

DOEpatents

An electromagnetic submerged pump has an outer cylindrical stator with an inner cylindrical conductive core for the submerged pumping of sodium in the cylindrical interstitial volume defined between the stator and core. The cylindrical interstitial volume is typically vertically oriented, and defines an inlet at the bottom and an outlet at the top. The outer stator generates upwardly conveyed toroidal magnetic fields, which fields convey preferably from the bottom of the pump to the top of the pump liquid sodium in the cold leg of a sodium cooled nuclear reactor. The outer cylindrical stator has a vertically disposed duct surrounded by alternately stacked layers of coil units and laminates. 14 figs.

Brynsvold, G.V.; Lopez, J.T.; Olich, E.E.; West, C.W.

1989-11-21

367

Remotely operable peristaltic pump  

NASA Technical Reports Server (NTRS)

A peristaltic pump is disclosed which includes a roller assembly on which is mounted a series of pump rollers. As the roller assembly is rotated by a drive gear the pump rollers are driven in reverse rotation by means of a stationary ring gear and pump roller gears. An upper pressure shoe plate and a lower pressure shoe plate are positioned above sets of flexible tubing. The tubing is sandwiched between the pressure shoe plates and the pump rollers. A highly compact pump is provided having twice as many fluid channel lines as is conventional. The peristaltic pump device may be remotely operated by means of a rotary actuator which rotates a driving hub to move the shoe plates by means of eccentrically mounted links. The pressure shoe plates may be moved by the rotary actuator to a loaded position in which the fluid lines are pinched by the pump rollers and fluid is pumped to an unloaded position in which the fluid lines are maintained in an undeformed, uncrimped configuration so that no creases or crimps are set into the fluid lines during periods of prolonged nonuse.

Belew, R. R. (inventor)

1986-01-01

368

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

369

Hubble Parameter in Bulk Viscous Cosmology  

E-print Network

We discuss influences of bulk viscosity on the Early Universe, which is modeled by Friedmann-Robertson-Walker metric and Einstein field equations. We assume that the matter filling the isotropic and homogeneous background is relativistic viscous characterized by ultra-relativistic equations of state deduced from recent lattice QCD simulations. We obtain a set of complicated differential equations, for which we suggest approximate solutions for Hubble parameter $H$. We find that finite viscosity in Eckart and Israel-Stewart fluids would significantly modify our picture about the Early Universe.

A. Tawfik; H. Mansour; M. Wahba

2009-12-01

370

Solving the viscous hydrodynamics order by order  

E-print Network

In this paper, we propose a method of solving the viscous hydrodynamics order by order in a derivative expansion. In such method, the zero order solution is just the one of the ideal hydrodynamics. All the other higher order corrections satisfy the same first-order partial differential equations but with different inhomogeneous terms. We therefore argue that our method could be easily extended to any orders. The problem of causality and stability will be released if the gradient expansion is guaranteed. This method might be of great help to both theoretical and numerical calculations of relativistic hydrodynamics.

Jian-Hua Gao; Shi Pu

2014-09-02

371

Two dimensional foam rheology with viscous drag  

E-print Network

We formulate and apply a continuum model that incorporates elasticity, yield stress, plasticity and viscous drag. It is motivated by the two-dimensional foam rheology experiments of Debregeas et al. [G. Debregeas, H. Tabuteau, and J.-M. di Meglio, Phys. Rev. Lett. 87, 178305 (2001)] and Wang et al [Y. Wang, K. Krishan, and M. Dennin, Phys. Rev. E 73, 031401 (2006)], and is successful in exhibiting their principal features an exponentially decaying velocity profile and strain localisation. Transient effects are also identified.

E. Janiaud; D. Weaire; S. Hutzler

2006-07-18

372

Simulation Of Unsteady, Viscous, Incompressible Flow  

NASA Technical Reports Server (NTRS)

Method for numerical solution of Navier-Stokes equations of viscous, incompressible flow developed based on use of fractional-step procedure. Accurate to second order in both space and time. Attempt made to minimize Poisson-equation difficulties by choosing pressures at centers and volume fluxes across faces of computational cells as dependent variables instead of familiar Cartesian components of velocity. Choice ensures satisfaction of discrete equation of conservation of mass to within round-off errors in any coordinate system and has favorable effects on convergence properties.

Rosenfeld, Moshe; Kwak, Dochan

1990-01-01

373

Point vortex in a viscous incompressible fluid  

NASA Astrophysics Data System (ADS)

A plane steady problem of a point vortex in a domain filled by a viscous incompressible fluid and bounded by a solid wall is considered. The existence of the solution of Navier-Stokes equations, which describe such a flow, is proved in the case where the vortex circulation ? and viscosity ? satisfy the condition |?| < 2 ??. The velocity field of the resultant solution has an infinite Dirichlet integral. It is shown that this solution can be approximated by the solution of the problem of rotation of a disk of radius ? with an angular velocity ? under the condition 2 ?? 2 ? ? ? as ? ? 0 and ???.

Pukhnachev, V. V.

2014-03-01

374

Well-pump alignment system  

DOEpatents

An improved well-pump for geothermal wells, an alignment system for a well-pump, and to a method for aligning a rotor and stator within a well-pump, wherein the well-pump has a whistle assembly formed at a bottom portion thereof, such that variations in the frequency of the whistle, indicating misalignment, may be monitored during pumping.

Drumheller, Douglas S. (Cedar Crest, NM)

1998-01-01

375

Component analysis report: Line shaft pump bushings, Warm Springs State Hospital, Warm Springs, Montana  

SciTech Connect

On 29 January 1981, the Failure Analysis Laboratory at Radian Corporation received two spider bushings from the State Hospital at Warm Springs, Montana, for metallurgical analysis. The bushings are from a 19 stage, 200 hp Worthington line shaft vertical turbine pump. The pump was set at 830 feet to test a low temperature geothermal well. One bushing was originally set near the top of the well; the other bushing had been set deep in the well. The bushings were reportedly manufactured from bronze sleeve-bearing material. After approximately 50 hours of intermittent operation, the pump began to experience severe vibration. The vibration appeared random in that it sometimes occurred immediately upon start up and other times occurred after several hours of operation. A Worthington service engineer tested the pump and made several recommendations to alleviate the problem. He concluded that excessive packing box friction, overloading, and shaft unscrewing caused the vibration. He also adjusted the vertical shaft and impeller clearances. The purposes of this analysis is to examine the shaft bushings for evidence of mechanical or corrosion damage that might have been related to the vibration problem.

McAlpin, Ron

1981-03-01

376

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

NASA Technical Reports Server (NTRS)

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

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

2004-01-01

377

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

NASA Technical Reports Server (NTRS)

A full-size acrylic model of a rotary blood pump was developed in order to utilize Particle Image Velocimetry (PIV) to make measurements of the fluid velocities and turbulent stresses throughout the device. The development of an understanding of the hemodynamics within the blood pump is critical to the development and validation of computational models. A blood analog solution, consisting of sodium iodide solution and glycerin, was developed to match physiological kinematic viscosity. The refractive indecies of the fluid, the pump casing and the impeller were matched to facilitate the use of PIV to make velocity measurements. Velocity measurements made in the volute exit/diffuser region are presented for pumps speeds of 3000-3850 rpm. At each speed data were obtained at a physiological pressure of 90 mmHg and at a maximum flow condition. Four hundred data pairs were used for each resultant mean velocity vector value, representing greater than an order of magnitude more data pairs than reported previously in the literature on similar devices and resulting in velocity uncertainty levels of approximately 2.9%.

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

2004-01-01

378

Wakes in viscous quark-gluon plasma  

NASA Astrophysics Data System (ADS)

With the dielectric function derived from the chromohydrodynamic approach, we investigate wakes in induced charge density and wake potential induced by a fast parton traveling through the viscous quark-gluon plasma (QGP). When the fast parton moves with a speed v = 0.55c which is less than the phase velocity of plasmon vp in QGP, the equicharge lines show a sign flip in the backward-forward spaces. While for v = 0.99c which is larger than vp, the equicharge lines show an oscillatory behavior. A Lennard-Jones potential and an oscillatory wake potential are found in the backward direction for v = 0.55c and v = 0.99c respectively. In addition, the viscous effect on wakes is also speed-dependent. When v = 0.55c, shear viscosity has a trivial impact on the wakes. While for v = 0.99c, shear viscosity modifies the strength and structure of the wakes significantly.

Jiang, Bing-Feng; Hou, De-Fu; Li, Jia-Rong

2014-04-01

379

Direct laser printing using viscous printer's ink  

SciTech Connect

The results of experiments on direct laser printing using viscous printer's ink with the help of a copper vapour laser (CVL)-based device are presented. The highly reflecting CVL cavity mirror was replaced by a spatial mirror modulator (SMM). Viscous printer's ink was used for printing. A pressure pulse produced at the boundary (on which an intensified and diminished image of the SMM was projected) between the ink and a transparency was used for transferring the ink to the plastic card. It was shown that the use of a CVL allowed a maximum printing speed of {approx}80 cm{sup 2} s{sup -1}, a resolution of 625 dpi and up to 15 gradations. The dependence of the emission intensity of the element being projected (pixel) on its diameter is studied. It is shown that an increase in the brightness of this element with decreasing its size is caused by the summation of the laser and amplified radiation. (laser applications and other topics in quantum electronics)

Nasibov, A S; Bagramov, V G; Berezhnoi, K V [P.N. Lebedev Physics Institute, Russian Academy of Sciences, Moscow (Russian Federation)

2006-02-28

380

Characterisation of a small viscous flow turbine  

SciTech Connect

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

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

2008-10-15

381

Pump apparatus including deconsolidator  

SciTech Connect

A pump apparatus includes a particulate pump that defines a passage that extends from an inlet to an outlet. A duct is in flow communication with the outlet. The duct includes a deconsolidator configured to fragment particle agglomerates received from the passage.

Sonwane, Chandrashekhar; Saunders, Timothy; Fitzsimmons, Mark Andrew

2014-10-07

382

Micromachined peristaltic pumps  

NASA Technical Reports Server (NTRS)

Micromachined pumps including a channel formed between a first membrane and a substrate or between first and second flexible membranes. A series of electrically conductive strips is applied to a surface of the substrate or one of the membranes. Application of a sequential voltage to the series of strips causes a region of closure to progress down the channel to achieve a pumping action.

Hartley, Frank T. (Inventor)

1999-01-01

383

Detection of pump degradation  

SciTech Connect

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

Casada, D.

1994-12-31

384

Invariant Manifolds and the Stability of Traveling Waves in Scalar Viscous Conservation Laws  

E-print Network

Invariant Manifolds and the Stability of Traveling Waves in Scalar Viscous Conservation Laws solutions of scalar, viscous conservation laws is inves- tigated by decomposing perturbations into three: invariant manifolds, stability of traveling waves, scalar viscous conservation laws, weighted function

385

Normetex Pump Alternatives Study  

SciTech Connect

A mainstay pump for tritium systems, the Normetex scroll pump, is currently unavailable because the Normetex company went out of business. This pump was an all-metal scroll pump that served tritium processing facilities very well. Current tritium system operators are evaluating replacement pumps for the Normetex pump and for general used in tritium service. An all-metal equivalent alternative to the Normetex pump has not yet been identified. 1. The ideal replacement tritium pump would be hermetically sealed and contain no polymer components or oils. Polymers and oils degrade over time when they contact ionizing radiation. 2. Halogenated polymers (containing fluorine, chlorine, or both) and oils are commonly found in pumps. These materials have many properties that surpass those of hydrocarbon-based polymers and oils, including thermal stability (higher operating temperature) and better chemical resistance. Unfortunately, they are less resistant to degradation from ionizing radiation than hydrocarbon-based materials (in general). 3. Polymers and oils can form gaseous, condensable (HF, TF), liquid, and solid species when exposed to ionizing radiation. For example, halogenated polymers form HF and HCl, which are extremely corrosive upon reaction with water. If a pump containing polymers or oils must be used in a tritium system, the system must be designed to be able to process the unwanted by-products. Design features to mitigate degradation products include filters and chemical or physical traps (eg. cold traps, oil traps). 4. Polymer components can work in tritium systems, but must be replaced regularly. Polymer components performance should be monitored or be regularly tested, and regular replacement of components should be viewed as an expected normal event. A radioactive waste stream must be established to dispose of used polymer components and oil with an approved disposal plan developed based on the facility location and its regulators. Polymers have varying resistances to ionizing radiation - aromatic polymers such as polyimide Vespel (TM) and the elastomer EPDM (ethylene propylene diene monomer) have been found to be more resistant to degradation in tritium than other polymers. This report presents information to help select replacement pumps for Normetex pumps in tritium systems. Several pumps being considered as Normetex replacement pumps are discussed.

Clark, E.

2013-04-25

386

Deep well solar pump  

SciTech Connect

This patent describes, in a pump having a source of gas under pressure, and a gas operated pump, a mechanism periodically injecting gas from the source of gas into the gas operated pump. It comprises: a long period pendulum turning towards a first position by gravity, an injection valve connected between the source of gas under pressure and the gas operated pump, a linkage between the pendulum and the injection valve. The linkage opening the injection valve when the pendulum is in the first position, an impulse tube connected between the injection valve and the gas operated pump, a member having a surface adjacent to the first position of the pendulum, and an elastic impulse bladder connected to the impulse tube adjacent to the surface so that inflation of the impulse bladder on the opening of the injection valve forces the impulse bladder against the pendulum urging the pendulum against the force of gravity toward a second position.

Vanek, J.

1990-02-06

387

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

388

Poloidal variation of viscous forces in the banana collisionality regime  

SciTech Connect

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

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

1992-12-01

389

Distribution of a viscous binder during high shear granulation--sensitivity to the method of delivery and its impact on product properties.  

PubMed

Binder distribution in the powder mass during high shear granulation is especially critical with the use of viscous liquid binders and with short processing times. A viscous liquid binder was delivered into the powder mass at two flow rates using three methods: pouring, pumping and spraying from a pressure pot. Binder content analyses at the scale of individual granules were conducted to investigate the impact of different delivery conditions on the homogeneity of binder distribution. There was clear evidence of non-uniformity of binder content among individual granules across all delivery conditions, particularly for the fast rates of delivery. Poorer reproducibility values of tablet thickness and disintegration time were observed when binder was poured but this may be overcome by pumping or spraying from the pressure pot. Greater homogeneity of binder distribution occurred with the slow rates of delivery and led to the earlier onset of granule growth and a consequent increase in granule size. Larger granule size and lower proportion of fines were in turn associated with increased granule bulk density and improvement of granule flow. In conclusion, delivery of a viscous binder at a slow rate either by pumping or via a pressure pot was most desirable during granulation. PMID:24269207

Tan, Bernice Mei Jin; Loh, Zhi Hui; Soh, Josephine Lay Peng; Liew, Celine Valeria; Heng, Paul Wan Sia

2014-01-01

390

Flowmeter determines mix ratio for viscous adhesives  

NASA Technical Reports Server (NTRS)

Flowmeter determines mix ratio for continuous flow mixing machine used to produce an adhesive from a high viscosity resin and aliphatic amine hardener pumped through separate lines to a rotary blender. The flowmeter uses strain gages in the two flow paths and monitors their outputs with appropriate instrumentation.

Lemons, C. R.

1967-01-01

391

Sampling pump with packer  

SciTech Connect

A groundwater sampling apparatus is described for withdrawing groundwater samples from a groundwater monitoring well, the apparatus having dedicatable inground components to prevent the apparatus from contaminating another well, the apparatus comprising: a pump adapted to be submerged in the groundwater within the well for pumping a portion of the groundwater, the pump being permanently dedicatable to the well and having a groundwater chamber with an inlet and an outlet; the groundwater chamber is connected with the portion of the groundwater in the well through the inlet when the pump is submerged in the groundwater; a packer associated with the pump, the packer reducing the volume of the portion of the groundwater which needs to be pumped in order to purge the well by isolating the portion of the groundwater; and a wellhead assembly permanently dedicatable to the well and adapted to be secured to the well to isolate the interior of the well from the above-ground surroundings, the wellhead assembly further including first conduit means communicable with the pump and the wellhead assembly, and second conduit means communicable with the packer and the wellhead assembly.

Niehaus, K.L.; Fischer, D.A.

1993-08-24

392

Pressure charged airlift pump  

DOEpatents

A pumping system is described for pumping fluids, such as water with entrained mud and small rocks, out of underground cavities such as drilled wells, which can effectively remove fluids down to a level very close to the bottom of the cavity and which can operate solely by compressed air pumped down through the cavity. The system utilizes a subassembly having a pair of parallel conduit sections (44, 46) adapted to be connected onto the bottom of a drill string utilized for drilling the cavity, the drill string also having a pair of coaxially extending conduits. The subassembly includes an upper portion which has means for connection onto the drill string and terminates the first conduit of the drill string in a plenum (55). A compressed air-driven pump (62) is suspended from the upper portion. The pump sucks fluids from the bottom of the cavity and discharges them into the second conduit. Compressed air pumped down through the first conduit (46) to the plenum powers the compressed air-driven pump and aerates the fluid in the second conduit to lift it to the earth's surface.

Campbell, Gene K. (Las Vegas, NV)

1983-01-01

393

Experimental study of highly viscous impinging jets  

SciTech Connect

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

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

1998-12-01

394

Structure formation in a ? viscous CDM universe  

NASA Astrophysics Data System (ADS)

The possibility of dark matter being a dissipative component represents an option for the standard view where cold dark matter (CDM) particles behave on large scales as an ideal fluid. By including a physical mechanism in the dark matter description like viscosity, we construct a more realistic model for the Universe. Also, the known small scale pathologies of the standard CDM model either disappear or become less severe. We study clustering properties of a ? CDM -like model in which dark matter is described as a bulk viscous fluid. The linear power spectrum, the nonlinear spherical "top hat" collapse, and the mass functions are presented. We use the analysis with such structure formation tools in order to place an upper bound on the magnitude of the dark matter's viscosity.

Velten, Hermano; Caramęs, Thiago R. P.; Fabris, Júlio C.; Casarini, Luciano; Batista, Ronaldo C.

2014-12-01

395

Electromagnetic properties of viscous charged fluids  

E-print Network

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

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

2014-01-01

396

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

NASA Technical Reports Server (NTRS)

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

Chen, Ching S.; Bridgeman, John O.

1990-01-01

397

On the dynamics of viscous masonry beams  

NASA Astrophysics Data System (ADS)

In this paper, we consider the longitudinal and transversal vibrations of the masonry beams and arches. The basic motivation is the seismic vulnerability analysis of masonry structures that can be modeled as monodimensional elements. The Euler-Bernoulli hypothesis is employed for the system of forces in the beam. The axial force and the bending moment are assumed to consist of the elastic and viscous parts. The elastic part is described by the no-tension material, i.e., the material with no resistance to tension and which accounts for the cases of limitless, as well as bounded compressive strength. The adaptation of this material to beams has been developed in Orlandi (Analisi non lineare di strutture ad arco in muratura. Thesis, 1999) and Zani (Eur J Mech A/Solids 23:467-484, 2004). The viscous part amounts to the Kelvin-Voigt damping depending linearly on the time derivatives of the linearized strain and curvature. The dynamical equations are formulated, and a mathematical analysis of them is presented. Specifically, following Gajewski et al. (Nichtlineare Operatorgleichungen und Operatordifferentialgleichungen. Akademie-Verlag, Berlin, 1974), the theorems of existence, uniqueness and regularity of the solution of the dynamical equations are recapitulated and specialized for our purposes, to support the numerical analysis applied previously in Lucchesi and Pintucchi (Eur J Mech A/Solids 26:88-105, 2007 ). As usual, for that the Galerkin method has been used. As an illustration, two numerical examples (slender masonry tower and masonry arch) are presented in this paper with the applied forces corresponding to the acceleration in the earthquake in Emilia Romagna in May 29, 2012.

Lucchesi, M.; Pintucchi, B.; Šilhavý, M.; Zani, N.

2014-04-01

398

Viscous fingering and liquid crystals in confinement  

NASA Astrophysics Data System (ADS)

This thesis focuses on two problems lying within the field of soft condensed matter: the viscous fingering or Saffman-Taylor instability and nematic liquid crystals in confinement. Whenever a low viscosity fluid displaces a high viscosity fluid in a porous medium, for example water pushing oil out of oil reservoirs, the interface between the two fluids is rendered unstable. Viscous fingers develop, grow and compete until a single finger spans all the way from inlet to outlet. Here, using a free energy lattice Boltzmann algorithm, we examine the Saffman-Taylor instability for two different wetting situations: (a) when neither of the two fluids wet the walls of the channel and (b) when the displacing fluids completely wets the walls. We demonstrate that curvature effects in the third dimension, which arise because of the wetting boundary conditions, can lead to a novel suppression of the instability. Recent experiments in microchannels using colloid-polymer mixtures support our findings. In the second part of the thesis we examine nematic liquid crystals confined in wedge-structured geometries. In these systems the final stable configuration of the liquid crystal system is controlled by the complex interplay between confinement, elasticity and surface anchoring. Varying the wedge opening angle this competition leads to a splay to bend transition mediated by a defect in the bulk of the wedge. Using a hybrid lattice Boltzmann algorithm we study the splay-bend transition and compare to recent experiments on {em fd} virus particles in microchannels. Our numerical results, in quantitative agreement with the experiments, enable us to predict the position of the defect as a function of opening angle, and elucidate its role in the change of director structure. This has relevance to novel energy saving, liquid crystal devices which rely on defect motion and pinning to create bistable director configurations.

Zacharoudiou, Ioannis

399

LED pumped Nd:YAG laser development program  

NASA Technical Reports Server (NTRS)

The results of a development program for light emitting diode (LED) pumped Nd:YAG lasers are described. An index matching method to increase the coupling efficiency of the laser is described. A solid glass half-cylinder of 5.0 by 5.6 centimeters was used for index matching and also as a pumping cavity reflector. The laser rods were 1.5 by 56 millimeters with dielectric coatings on both end surfaces. The interfaces between the diode array, glass cylinder, and laser rod were filled with viscous fluid of refractive index n = 1.55. Experiments performed with both the glass cylinder and a gold coated stainless steel reflector of the same dimensions under the same operating conditions indicate that the index matching cylinder gave 159 to 200 percent improvement of coupling efficiency over the metal reflector at various operating temperatures.

Farmer, G. I.; Kiang, Y. C.; Lynch, R. J.

1973-01-01

400

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

NASA Technical Reports Server (NTRS)

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

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

2011-01-01

401

Keeping Hearts Pumping  

NASA Technical Reports Server (NTRS)

A collaboration between NASA, Dr. Michael DeBakey, Dr. George Noon, and MicroMed Technology, Inc., resulted in a life-saving heart pump for patients awaiting heart transplants. The MicroMed DeBakey VAD functions as a "bridge to heart transplant" by pumping blood throughout the body to keep critically ill patients alive until a donor heart is available. Weighing less than 4 ounces and measuring 1 inch by 3 inches, the pump is approximately one-tenth the size of other currently marketed pulsatile VADs. This makes it less invasive and ideal for smaller adults and children. Because of the pump's small size, less than 5 percent of the patients implanted developed device-related infections. It can operate up to 8 hours on batteries, giving patients the mobility to do normal, everyday activities.The MicroMed DeBakey VAD is a registered trademark of MicroMed Technology, Inc.

2002-01-01

402

Absorption heat pump system  

DOEpatents

The efficiency of an absorption heat pump system is improved by conducting liquid from a second stage evaporator thereof to an auxiliary heat exchanger positioned downstream of a primary heat exchanger in the desorber of the system.

Grossman, Gershon (Oak Ridge, TN)

1984-01-01

403

Insulin pump therapy.  

PubMed

Insulin pump therapy makes use of an external device to deliver insulin continuously from a refillable storage reservoir by means of a cannula placed under the skin. A pump is intended to simulate pancreatic function in that it can be programmed to deliver an adjustable basal rate of insulin throughout the day, with higher infusion rates triggered by the push of a button at meal times or to correct a high blood glucose fluctuation. Insulin pumps have been mainly used in patients with type 1 diabetes. There are a number of recent technological innovations that support a more sophisticated approach to insulin dosing using insulin pumps.3 In this article we provide an overview of the use of such therapy. PMID:22966100

2012-09-01

404

Entrapment Type Vacuum Pumps  

NSDL National Science Digital Library

This is a description for a learning module from Maricopa Advanced Technology Education Center. This PDF describes the module; access may be purchased by visiting the MATEC website. Entrapment type pumps operate primarily in the high to ultra-high vacuum ranges. The discussion in this MATEC module includes applications, theory of operation, operating range and preventative maintenance. The focus is on three major types of pumps: cryosorption, cryogenic and sputter-ion. The overall performance of these types of pumps depends on a variety of parameters. For example, it is important that learners understand the balance between pumping speed and capacity. Competency is demonstrated as the learners specify systems for defined process applications.

405

The Insulin Pump  

PubMed Central

Subcutaneous continuous insulin infusion systems deliver insulin at a basal rate designed to keep blood glucose levels normal in the non-fed state. Additional insulin is delivered at meal time. Pumps can provide near optimal control of blood glucose concentrations in selected, highly motivated patients. The pump provides better diabetic control than once daily insulin injections, although several daily injections can provide comparable control. Optimal control with the pump causes some short-term beneficial metabolic changes, but there are no controlled clinical trials evaluating the long-term effect on complications. Insulin pump therapy should be initiated only for highly motivated, well instructed patients in a supportive clinical setting. The hazards include rapid development of uncontrolled diabetes when insulin infusion stops, and development of hypoglycemia in the basal rate mode. PMID:21274024

Toews, C. J.

1985-01-01

406

Well pumping unit  

SciTech Connect

A pump operating unit is described for reciprocating a pump component operably connected to an output member of the pump operating unit which moves in a reciprocating manner. The pump operating unit consists of a large diameter wheel, a power unit having a small diameter output pulley, a belt encircling the small diameter pulley and large diameter wheel for driving the wheel at a slow rotational speed as compared to the rotational speed of the pulley, an actuating cable, means attaching one end of the cable eccentrically to the large diameter wheel, the other end of the cable being anchored and the intermediate portion of the cable passing over a plurality of pulleys, support means for the wheel, cable pulleys and anchor point for the cable, a traveling pulley engaging a portion of the cable, second cable means forming the output member connected to the traveling pulley and a head pulley supporting the second cable means.

Slater, F.W.

1986-05-06

407

Resorption heat pump  

Microsoft Academic Search

Resorption processes are based on at least two solid-sorption reactors application. The most favorable situation for the resorption heat pumps is the case, when the presence of a liquid phase is impossible. From simple case––two reactors with two salts to complicated system with two salts+active carbon fiber (fabric) and two branch of the heat pump acting out of phase to

L. L Vasiliev; D. A Mishkinis; A. A Antukh; A. G Kulakov

2004-01-01

408

Lunar Base Heat Pump  

NASA Technical Reports Server (NTRS)

The objective of this project was to investigate the feasibility of constructing a heat pump suitable for use as a heat rejection device in applications such as a lunar base. In this situation, direct heat rejection through the use of radiators is not possible at a temperature suitable for lde support systems. Initial analysis of a heat pump of this type called for a temperature lift of approximately 378 deg. K, which is considerably higher than is commonly called for in HVAC and refrigeration applications where heat pumps are most often employed. Also because of the variation of the rejection temperature (from 100 to 381 deg. K), extreme flexibility in the configuration and operation of the heat pump is required. A three-stage compression cycle using a refrigerant such as CFC-11 or HCFC-123 was formulated with operation possible with one, two or three stages of compression. Also, to meet the redundancy requirements, compression was divided up over multiple compressors in each stage. A control scheme was devised that allowed these multiple compressors to be operated as required so that the heat pump could perform with variable heat loads and rejection conditions. A prototype heat pump was designed and constructed to investigate the key elements of the high-lift heat pump concept. Control software was written and implemented in the prototype to allow fully automatic operation. The heat pump was capable of operation over a wide range of rejection temperatures and cooling loads, while maintaining cooling water temperature well within the required specification of 40 deg. C +/- 1.7 deg. C. This performance was verified through testing.

Walker, D.; Fischbach, D.; Tetreault, R.

1996-01-01

409

Remotely Adjustable Hydraulic Pump  

NASA Technical Reports Server (NTRS)

Outlet pressure adjusted to match varying loads. Electrohydraulic servo has positioned sleeve in leftmost position, adjusting outlet pressure to maximum value. Sleeve in equilibrium position, with control land covering control port. For lowest pressure setting, sleeve shifted toward right by increased pressure on sleeve shoulder from servovalve. Pump used in aircraft and robots, where hydraulic actuators repeatedly turned on and off, changing pump load frequently and over wide range.

Kouns, H. H.; Gardner, L. D.

1987-01-01

410

Comparison of measurement data at the impeller exit of a centrifugal compressor measured with both pneumatic and fast-response probes  

SciTech Connect

The main goal of these investigations was the refined measurement of unsteady high speed flow in a centrifugal compressor using the advanced FRAP{reg_sign} fast-response aerodynamic probe system. The present contribution focuses on the impeller exit region and shows critical comparisons between fast-response (time-resolving) and conventional pneumatic probe measurement results. Three probes of identical geometry (one fast and two pneumatic) were used to perform wall-to-wall traverses close to impeller exit. The data shown refer to a single running condition near the best point of the stage. The mass flow obtained from different probe measurements and from the standard orifice measurement were compared. Stage work obtained from temperature rise measured with a FRAP{reg_sign} probe and from impeller outlet velocity vectors fields by using Euler`s turbine equation are presented. The comparison in terms of velocity magnitude and angle distribution is quite satisfactory, indicating the superior DC measurement capabilities of the fast-response probe system.

Roduner, C.; Koeppel, P.; Kupferschmied, P.; Gyarmathy, G. [ETH-Swiss Federal Inst. of Tech., Zurich (Switzerland)

1999-07-01

411

Stabilization of radiation pressure dominated accretion disks through viscous fluctuations  

NASA Astrophysics Data System (ADS)

Aims: The standard thin accretion disk model has successfully explained the soft X-ray spectra of Galactic black hole systems and perhaps the UV emission of active galactic nuclei. However, radiation pressure dominated disks are known to be viscously unstable and should produce high-amplitude oscillations that are typically not observed. Instead, these sources exhibit a stochastic variability that may naturally arise through viscous fluctuations in a turbulent disk. Here we investigate whether these aperiodic viscous fluctuations can stabilize the inner radiation pressure dominated disks and hence maybe the answer to a forty-year old problem in accretion disk theory. Methods: The structure and evolution of a time-dependent accretion disk around a black hole is solved numerically. We incorporated fluctuations in the disk by considering stochastic variations in the viscous parameter ? on the local viscous time-scale. We studied both locally stable disks where the viscous stress scales with the gas pressure and locally unstable disks where the stress scales as the total pressure. We considered steady state disk parameters pertaining to both stellar and supermassive black holes. Results: For locally stable disks, the power spectra of the luminosity variations are found to inversely scale with frequency, i.e., P(f) ? 1/f as expected from analytical studies of linear viscous fluctuations. For unstable disks, where the viscous stress scales with the total pressure, the standard oscillatory solutions are seen when the viscous fluctuation amplitude is low. Increasing the fluctuation amplitude decreases the amplitude of these oscillations until for a sufficiently high (near unity) fluctuation amplitude, the oscillatory behavior disappears and the luminosity variation of the disk becomes stochastic. This study may explain why many accreting black holes, although they show sufficiently high accretion rates to develop the radiation pressure instability, do not exhibit high-amplitude regular outbursts, or, like the micro-quasar GRS 1915+105, produce diminished versions of these outburst only in some specific spectral states.

Janiuk, A.; Misra, R.

2012-04-01

412

Hydraulic development of high specific-speed pump-turbines by means of an inverse design method, numerical flow-simulation (CFD) and model testing  

NASA Astrophysics Data System (ADS)

In recent years an increased interest in pump-turbines has been recognized in the market. The rapid availability of pumped storage schemes and the benefits to the power system by peak lopping, providing reserve and rapid response for frequency control are becoming of growing advantage. In that context it is requested to develop pump-turbines that reliably stand dynamic operation modes, fast changes of the discharge rate by adjusting the variable diffuser vanes as well as fast changes from pump to turbine operation. Within the present study various flow patterns linked to the operation of a pump-turbine system are discussed. In that context pump and turbine mode are presented separately and different load cases at both operation modes are shown. In order to achieve modern, competitive pump-turbine designs it is further explained which design challenges should be considered during the geometry definition of a pump-turbine impeller. Within the present study a runner-blade profile for a low head pump-turbine has been developed. For the initial hydraulic runner-blade design, an inverse design method has been applied. Within this design procedure, a first blade geometry is generated by imposing the pressure loading-distribution and by means of an inverse 3D potential-flow-solution. The hydraulic behavior of both, pump-mode and turbine-mode is then evaluated by solving the full 3D Navier-Stokes equations in combination with a robust turbulence model. Based on this initial design the blade profile has been further optimized and redesigned considering various hydraulic pump-turbine requirements. Finally, the progress in hydraulic design is demonstrated by model test results which show a significant improvement in hydraulic performance compared to an existing reference design.

Kerschberger, P.; Gehrer, A.

2010-08-01

413

Lunar base heat pump  

NASA Technical Reports Server (NTRS)

A heat pump is a device which elevates the temperature of a heat flow by a means of an energy input. By doing this, the heat pump can cause heat to transfer faster from a warm region to a cool region, or it can cause heat to flow from a cool region to a warmer region. The second case is the one which finds vast commercial applications such as air conditioning, heating, and refrigeration. Aerospace applications of heat pumps include both cases. The NASA Johnson Space Center is currently developing a Life Support Systems Integration Facility (LSSIF, previously SIRF) to provide system-level integration, operational test experience, and performance data that will enable NASA to develop flight-certified hardware for future planetary missions. A high lift heat pump is a significant part of the TCS hardware development associated with the LSSIF. The high lift heat pump program discussed here is being performed in three phases. In Phase 1, the objective is to develop heat pump concepts for a lunar base, a lunar lander, and for a ground development unit for the SIRF. In Phase 2, the design of the SIRF ground test unit is being performed, including identification and evaluation of safety and reliability issues. In Phase 3, the SIRF unit will be manufactured, tested, and delivered to the NASA Johnson Space Center.

Goldman, Jeffrey H.; Tetreault, R.; Fischbach, D.; Walker, D.

1994-01-01

414

Method for formation of subsurface barriers using viscous colloids  

DOEpatents

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

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

1998-01-01

415

Rayleigh-Taylor instability in quantum magnetized viscous plasma  

SciTech Connect

Quantum effects on Rayleigh-Taylor instability of stratified viscous plasmas layer under the influence of vertical magnetic field are investigated. By linearly solving the viscous QMHD equations into normal mode, a forth-order ordinary differential equation is obtained to describe the velocity perturbation. Then the growth rate is derived for the case where a plasma with exponential density distribution is confined between two rigid planes. The results show that, the presence of vertical magnetic field beside the quantum effect will bring about more stability on the growth rate of unstable configuration for viscous plasma, which is greater than that of inviscous plasma.

Hoshoudy, G. A., E-mail: g_hoshoudy@yahoo.com [South Valley University, Department of Applied Mathematics, Faculty of Science (Egypt)

2011-09-15

416

The Evolution of Ion Pumps.  

ERIC Educational Resources Information Center

Constructs an evolutionary sequence to account for the diversity of ion pumps found today. Explanations include primary ion pumps in bacteria, features and distribution of ATP-driven pumps, preference for cation transport, and proton pump reversal. The integrated evolutionary hypothesis should encourage new experimental approaches. (DH)

Maloney, Peter C.; Wilson, T. Hastings

1985-01-01

417

Correlation of cavitating centrifugal pumps  

Microsoft Academic Search

The foreknowledge of the minimum NPSH ('net positive suction head') required for a cavitation-free performance of centrifugal pumps is important for a safe and sound operation of these machines. The required NPSH varies from pump to pump, from fluid to fluid, and from temperature to temperature of the pumped fluid. This is known as the thermodynamic effect. The methods currently

V. J. Zika

1984-01-01

418

Axial pumps for propulsion systems  

NASA Technical Reports Server (NTRS)

The development of axial flow hydrogen pumps is examined. The design features and the performance data obtained during the course of the development programs are discussed. The problems created by the pump characteristics are analyzed. Graphs of four stage pump performance for various turbine blade configurations are developed. The characteristics and performance of a variety of pumps are included.

Huppert, M. C.; Rothe, K.

1974-01-01

419

Thermally Actuated Hydraulic Pumps  

NASA Technical Reports Server (NTRS)

Thermally actuated hydraulic pumps have been proposed for diverse applications in which direct electrical or mechanical actuation is undesirable and the relative slowness of thermal actuation can be tolerated. The proposed pumps would not contain any sliding (wearing) parts in their compressors and, hence, could have long operational lifetimes. The basic principle of a pump according to the proposal is to utilize the thermal expansion and contraction of a wax or other phase-change material in contact with a hydraulic fluid in a rigid chamber. Heating the chamber and its contents from below to above the melting temperature of the phase-change material would cause the material to expand significantly, thus causing a substantial increase in hydraulic pressure and/or a substantial displacement of hydraulic fluid out of the chamber. Similarly, cooling the chamber and its contents from above to below the melting temperature of the phase-change material would cause the material to contract significantly, thus causing a substantial decrease in hydraulic pressure and/or a substantial displacement of hydraulic fluid into the chamber. The displacement of the hydraulic fluid could be used to drive a piston. The figure illustrates a simple example of a hydraulic jack driven by a thermally actuated hydraulic pump. The pump chamber would be a cylinder containing encapsulated wax pellets and containing radial fins to facilitate transfer of heat to and from the wax. The plastic encapsulation would serve as an oil/wax barrier and the remaining interior space could be filled with hydraulic oil. A filter would retain the encapsulated wax particles in the pump chamber while allowing the hydraulic oil to flow into and out of the chamber. In one important class of potential applications, thermally actuated hydraulic pumps, exploiting vertical ocean temperature gradients for heating and cooling as needed, would be used to vary hydraulic pressures to control buoyancy in undersea research vessels. Heretofore, electrically actuated hydraulic pumps have been used for this purpose. By eliminating the demand for electrical energy for pumping, the use of the thermally actuated hydraulic pumps could prolong the intervals between battery charges, thus making it possible to greatly increase the durations of undersea exploratory missions.

Jones, Jack; Ross, Ronald; Chao, Yi

2008-01-01

420

Well-pump alignment system  

DOEpatents

An improved well-pump for geothermal wells, an alignment system for a well-pump, and to a method for aligning a rotor and stator within a well-pump are disclosed, wherein the well-pump has a whistle assembly formed at a bottom portion thereof, such that variations in the frequency of the whistle, indicating misalignment, may be monitored during pumping. 6 figs.

Drumheller, D.S.

1998-10-20

421

A micromachined vapor jet pump  

Microsoft Academic Search

Initial results from a micro-pump based on the principle of macroscopic vapor-jet- and diffusion-pumps are presented. A mathematical description of the underlying gas dynamics is given and equations for the calculation of pump geometry are derived. Several planar micro-vapor jet pumps with different geometries were designed and fabricated by means of silicon micromachining (STS Advanced Silicon Etch™). The pumps consist

M. Doms; J. Mueller

2005-01-01

422

Experimental studies on the optimization design of a low specific speed centrifugal pump  

NASA Astrophysics Data System (ADS)

Start your abstract here... For a low specific speed centrifugal pump with the requirement of high efficiency of 68% and non-overload power characteristics, series experimental studies, by matching 9 volutes with 19 impellers were done. By combining the former research results about the splitters and the non-overload theory in centrifugal pump, the theoretical conditions to achieve the property of non-overload in a centrifugal pump with splitters was analyzed, and formulas to estimate the maximum shaft power and its position are derived. Based on the requirement of high efficiency and non-overload, blade outlet angle ?2, blade outlet width b2, volute throat area Ft and the inlet diameter of splitters Di were chosen with three levels to design a normal L9 (34) orthogonal test scheme. Meanwhile, the optimized design scheme was determined, and corresponding test was done also, it demonstrates that the experiment purpose was reached, the design method to combine the splitters and non-overload theory is reasonable, which can get the property of high efficiency and non-overload.

Zhang, J. F.; Yuan, Y.; Yuan, S. Q.; Lu, W. G.; Yuan, J. P.

2012-11-01

423

Hydrodynamic optimization of trust ring pump and lubricating oil system for large hydroelectric units thrust bearing  

NASA Astrophysics Data System (ADS)

Thrust-ring-pump is a kind of extreme-low specific speed centrifugal pump with special structure as numerous restrictions form thrust bearing and operation conditions of hydro turbine generator unit. Because the oil circulating and cooling system with thrust-ring- pump has a lot of advantages in maintenance and compactness in structure, it has widely been used in large and medium-sized hydro-generator units. Since the diameter and the speed of the thrust ring is limited by the generator set, the matching relationship between the flow passage inside the thrust ring (equivalent to impeller) and oil bath (equivalent to volute) has great influence on hydrodynamic performance of thrust-ring-pump, additionally, the head and discharge are varying with the operation conditions of hydro-generator unit and characteristic of the oil circulating and cooling system. As so far, the empirical calculation method is employed during the actual engineering design, in order to guarantee the operating performance of the oil circulating and cooling system with thrust-ring-pump at different conditions, a collaborative hydrodynamic design and optimization of both the oil circulating and cooling system and thrust-ring-pump is purposed in this paper. Firstly, the head and discharge required at different conditions are decided by 1D flow numerical simulation of the oil circulating and cooling system. Secondly, the flow passages of thrust-ring-pump are empirically designed under the restrictions of diameter and the speed of the thrust ring according to the head and discharge from the simulation. Thirdly, the flow passage geometry matching optimization between holes inside the thrust ring and oil bath is implemented by means of 3D flow simulation and performance prediction. Then, the pumps and the oil circulating and cooling system are collaborative hydrodynamic optimized with predicted head- discharge curve and the efficiency-discharge curve of thrust-ring-pump. The presented methodology has been adopted by DFEM in design process of thrust-ring-pump and it shown that can effectively improve and guarantee the performance of the oil circulating and cooling system.

Lai, X.; Lu, Z.; Zhang, X.; Yang, S.

2014-12-01

424

Nonlinear asymptotic stability of viscous shock profiles for conservation laws  

Microsoft Academic Search

This paper concerns the asymptotic stability of viscous shock profiles for hyperbolic systems of conservation laws with positive definite viscosity. We prove that such profiles, for weak shocks, are stable to small perturbations with integral zero.

Jonathan Goodman

1986-01-01

425

Spectral control of viscous alignment for deformation invariant image matching  

E-print Network

We present a new approach to deformation invariant image matching. Our approach retains the broad range of linear and nonlinear deformations that viscous alignment methods can model, but introduces a selectivity that is ...

Yang, Christopher Minzer

2009-01-01

426

Understanding the evolution of miscible viscous fingering patterns  

E-print Network

Viscous fingering, the hydrodynamic instability that occurs when a lower viscosity fluid displaces a higher viscosity fluid, creates complex patterns in porous media flows. Fundamental facets of the displacement process, ...

Chui, Jane (Jane Yuen Yung)

2012-01-01

427

Viscous effect on airfoils for unsteady transonic flows  

NASA Technical Reports Server (NTRS)

The viscous effect on aerodynamic performance of an arbitrary airfoil executing low frequency maneuvers during transonic flight was investigated. The small disturbance code, LTRAN2, was modified by using a conventional integral method, BLAYER, for the boundary layer and an empirical relation, viscous wedge, for simulating the suddenly thickened boundary layer behind the shock. Before the shock, only the boundary layer displacement thickness was evaluated. After the shock, the empirical wedge thickness was superimposed on the boundary layer thickness along the surface as well as in the wake region. The pressure coefficients were calculated for both steady and unsteady states. The viscous solution takes fewer iterations to obtain the converged steady state solution. Comparisons made with experimental data and the inviscid solution show that the viscous solution agrees better with the experimental data with about the same (or slightly less) amount of computational time.

Lee, S. C.

1982-01-01

428

Scaling analysis of flow in channel with viscous dissipation  

NSDL National Science Digital Library

Scaling analysis is used to predict the functional dependence and order of magnitude of the maximum temperature difference between the fluid and the channel wall, for fully developed flow between parallel plates with viscous dissipation.

Krane, Matthew J.

2008-10-25

429

Numerical simulation of mixing in viscous-fingering displacements  

E-print Network

Mixing of two fluids in viscously unstable displacements is far from being fully understood. It is not known how mixing efficiency depends on the viscosity contrast between the fluids, especially for advection-dominated ...

Jha, Birendra. S.M. Massachusetts Institute of Technology

2010-01-01

430

Pump cavitation of the HFIR primary coolant pumps during pump coastdown initiated by a LOCA  

SciTech Connect

The objective of this effort was to present the effects of pump cavitation within the context of the RELAP5/MOD2 High Flux Isotope Reactor (HFIR) primary coolant system input model. Using the existing data available for the main circulating pumps, such a scheme was developed. The head degradation associated with pump cavitation was achieved in the model by modulating the pump speed value input to the RELAP5 pump model. The modulated pump speed is less than the noncavitating pump speed, thus producing the required head degradation. 10 refs., 5 figs.

Wendel, M.; Morris, D.G.

1991-01-01

431

Low Mach Number Limit of Viscous Compressible Magnetohydrodynamic Flows  

E-print Network

The relationship between the compressible magnetohydrodynamic flows with low Mach number and the incompressible magnetohydrodynamic flows is investigated. More precisely, the convergence of weak solutions of the compressible isentropic viscous magnetohydrodynamic equations to the weak solutions of the incompressible viscous magnetohydrodynamic equations is proved as the density becomes constant and the Mach number goes to zero, that is, the corresponding incompressible limits are justified when the spatial domain is a periodic domain, the whole space, or a bounded domain.

Xianpeng Hu; Dehua Wang

2009-04-23

432

Viscous damping of toroidal angular momentum in tokamaks  

SciTech Connect

The Braginskii viscous stress tensor formalism was generalized to accommodate non-axisymmetric 3D magnetic fields in general toroidal flux surface geometry in order to provide a representation for the viscous damping of toroidal rotation in tokamaks arising from various “neoclassical toroidal viscosity” mechanisms. In the process, it was verified that the parallel viscosity contribution to damping toroidal angular momentum still vanishes even in the presence of toroidal asymmetries, unless there are 3D radial magnetic fields.

Stacey, W. M. [Georgia Tech Fusion Research Center, Atlanta, Georgia 30332 (United States)

2014-09-15

433

Visualization of emergency viscous two-phase venting behaviors  

Microsoft Academic Search

Safety design of emergency relief system must consider adequate vent sizing whether the flow is a single phase or two-phase vapor–liquid flow and two-phase flow generally requires a larger relief area. It is an even more complex situation due to the effect of friction loss in a relief line with high viscous fluids. Generally, viscous fluids are polymer solutions or

Yih-Shing Duh; Kwan-Hua Hu; Jy-Cheng Chang; Chen-Shan Kao

2009-01-01

434

DLA simulation with sticking probability for viscous fingering  

Microsoft Academic Search

The morphological evolution of viscous fingering, which occurred in two-dimensional Hele-Shaw cells with various displaced fluids, were simulated using a modified diffusion- limited aggregation (DLA) model on off-lattices. Different from other DLA models, the present model introduced three adjusted parameters. They control the morphological evolution of DLA clusters from a skeletal pattern to a fleshy pattern, so that experimental viscous

Jianhua Zhang; Jun Luo; Zhenhua Liu

2011-01-01

435

USE OF POLYMERS TO RECOVER VISCOUS OIL FROM UNCONVENTIONAL RESERVOIRS  

Microsoft Academic Search

This final technical progress report summarizes work performed the project, 'Use of Polymers to Recover Viscous Oil from Unconventional Reservoirs.' The objective of this three-year research project was to develop methods using water soluble polymers to recover viscous oil from unconventional reservoirs (i.e., on Alaska's North Slope). The project had three technical tasks. First, limits were re-examined and redefined for

Randall Seright

2011-01-01

436

Viscous damping of toroidal angular momentum in tokamaks  

NASA Astrophysics Data System (ADS)

The Braginskii viscous stress tensor formalism was generalized to accommodate non-axisymmetric 3D magnetic fields in general toroidal flux surface geometry in order to provide a representation for the viscous damping of toroidal rotation in tokamaks arising from various "neoclassical toroidal viscosity" mechanisms. In the process, it was verified that the parallel viscosity contribution to damping toroidal angular momentum still vanishes even in the presence of toroidal asymmetries, unless there are 3D radial magnetic fields.

Stacey, W. M.

2014-09-01

437

An elastic-viscous-plastic model for sea ice dynamics  

SciTech Connect

The standard model for sea ice dynamics treats the ice pack as a viscous-plastic material that flows plastically under typical stress conditions but behaves as a linear viscous fluid where strain rates are small and the ice becomes nearly rigid. Because of large viscosities in these regions, implicit numerical methods are necessary for timesteps larger than a few seconds. Current solution methods for these equations use iterative relaxation methods, which are time consuming, scale poorly with mesh resolution, and are not well adapted to parallel computation. To remedy this, we have developed and tested two separate methods. First, by demonstrating that the viscous-plastic rheology can be represented by a symmetric, negative definite matrix operator, we have implemented the faster and better behaved preconditioned conjugate gradient method. Second, realizing that only the response of the ice on time scales associated with wind forcing need be accurately resolved, we have modified the model to reduce to the viscous-plastic model at these time scales; at shorter time scales the adjustment process takes place by a numerically efficient elastic wave mechanism. This modification leads to a fully explicit numerical scheme which further improves the computational efficiency and is an advantage for implementations on parallel machines. Furthermore, we observe that the standard viscous-plastic model has poor dynamic response to forcing on a daily time scale, given the standard time step (1 day) used by the ice modeling community. In contrast, the explicit discretization of the elastic wave mechanism allows the elastic-viscous-plastic model to capture the ice response to variations in the imposed stress more accurately. Thus, the elastic-viscous-plastic model provides more accurate results for shorter time scales associated with physical forcing, reproduces viscous-plastic model behavior on longer time scales, and is computationally more efficient. 49 refs., 13 figs., 6 tabs.

Hunke, E.C.; Dukowicz, J.K.

1996-10-01

438

Viscous and elastic-plastic material model in the ABAQUS  

Microsoft Academic Search

The implementation of constitutive equations into a structural analysis computer program