Hydraulic Performance Of Pump Research Articles

Non-newtonian laminar flow machine rotor design by using topology optimization

Flow machines are widely used in industry through devices such as hydraulic turbines and pumps. Most part of these devices work with newtonian fluids, however, there are some specific devices dedicated to work with non-newtonian fluids, such as blood pumps. The main function of a blood pump is to have a suitable hydraulic performance while maintaining good haematological compatibility which consists of avoiding hemolysis (release of hemoglobin from red blood cells) and thrombosis (clotting). However, the challenge of improving the performance of these non-newtonian fluid machines requires the solution of an inverse-based design optimization problem, in which an oriented search must be conducted to obtain the optimized design. The rotor is a main component in the non-newtonian pump and the design of rotor topology can play an important role in the pump performance and its haematological conditions. Thus, performance improvement of these devices can be achieved by using topology optimization techniques. The optimization of pump hydraulic performance can be achieved by minimizing dissipative energy and power consumption and for the improvement of the haematological conditions, it is proposed to minimize the vorticity. Thus, in this work, topology optimization techniques are applied for designing the rotor pump such that the energy dissipation, vorticity, and power consumption are minimized considering non-Newtonian fluid. A two-dimensional finite element derived for a rotating frame is applied to model the rotor flow behavior. The modeling predicts the flow field between relative two blades of a rotor without considering the influence of the volute. A modified Cross model is adopted for the non-Newtonian fluid modeling. It is assumed that the fluid is flowing an idealized porous medium subjected to a friction force, which is proportional to the fluid velocity and the inverse local permeability. A porous flow model is considered with a continuous (gray) permeability design variable for each element that defines the local permeability of the medium and allows the transition between fluid and solid property. The design optimization problem is solved by using the method of moving asymptotes (MMA). Numerical examples are presented to illustrate this methodology aiming blood pump applications. A comparison among designs obtained by considering newtonian and non-newtonian fluid is included. Finally, it is verified that an improvement of the hemolysis index can be achieved by minimizing the vorticity in the rotor.

Simulation of cavitation performance of an axial flow pump with inlet guide vanes

The cavitation performance of an axial flow pump with inlet guide vanes for different flow rates is studied in this article. The effects of inlet guide vanes on pump hydraulic performance and cavitation are investigated, where the total vapor fraction of impeller zone ( Ftv) is calculated to predict the critical net positive suction head, which is compared with that predicted by efficiency criterion for different flow rates. The influences of the development of cavitation on internal flow in impeller zone are also investigated. The results obtained show that the cavitation performance of axial flow pump can be improved at off-design flow conditions by adjusting angles of inlet guide vanes to positive values at low flow rates and by regulating angles of inlet guide vanes to negative values at high flow rates. As the net positive suction head decreases, the vapor fraction first increases slowly and then increases greatly, clearly presenting cavitation process from inception to full development, which can be used to predict the required net positive suction head. When net positive suction head decreases to the value around required net positive suction head, the cavitation zone from tip of blade suction side close to leading edge and the cavitation zone from hub part of the blade suction side connect together. After the connection, the cavitation zones have great influence on the velocity flow, leading to the decrease in pump performance.

An improved turbulence model for separation flow in a centrifugal pump

For the stable and reliable operation of centrifugal pump, the transient flow must be studied and the separation region should be avoided. Three-dimensional, incompressible, steady, and transient flows in a centrifugal pump at specific speed within 74 were numerically studied using shear stress transport k- ω turbulence model, and an improved explicit algebraic Reynolds stress model–rotation-curvature turbulence model was proposed by considering the effects of rotation and curvature in the impeller passages in this work. Steady and transient computations were conducted to compare with the experiments. The comparison of pump hydraulic performance showed that the explicit algebraic Reynolds stress model–rotation-curvature turbulence model was better than the original model, especially between 0.6 QBEP and 1.2 QBEP; the improved model could enhance the head prediction of pump by about 1%–7% than that with the original model. Then, the visualization of the vortex evolution was observed to validate the unsteady simulations. Good agreement was investigated between calculations and visualizations. It is indicated that the explicit algebraic Reynolds stress model–rotation-curvature model can successfully capture the separation flow.

Simulation and Testing of the Hydraulic Performance of the Sliding Vane Pump

Summary A new all-metal sliding-vane pump (SVP) and matching lift system were developed as an alternative to the low efficiency and poor high-temperature performance of conventional artificial-lift systems. Numerical simulation and laboratory tests were used to conduct a comparative study of the hydraulic performance of the pump. The effects of pump-lifting-pressure difference and rotational speed on pump rate and efficiency were studied. The test results showed that, if the rotation speed is fixed, the pump rate and efficiency will decrease with an increase in required pressure difference. With a constant pressure difference, the flow rate can be controlled by varying the pump speed. On the basis of computational fluid dynamics (CFD) and finite-element-method (FEM) numerical simulation, a numerical model of the SVP was created. The pressure and fluid-flow distribution in the vane pump were determined under zero pump-pressure-difference condition, which helped realize the working principles of the pump. The simulation results agreed well with the test results, thus validating the reliability of the numerical models in this paper.

立軸斜流ポンプ羽根車に働く軸スラストの挙動

Axial thrust forces acting on an impeller of a diffuser type mixed flow pump have been studied. The behavior of the axial thrust generated by the vortex occurrence in a pump intake sump was investigated. The thrust of distinct discontinuities such as hysteresis phenomenon from a pump hydraulic performance was measured. In pump partial load operation the axial thrust increases discontinuously because of the reverse flow at impeller inlet. Synchronous and non-synchronous components of axial thrust increase during the onset of reverse flow zones. A prediction method for static axial thrust was derived based on Oshima's theory accounting for the pump suction bell-mouth pressure reduction due to vortex. Qualitative comparison with the measured experimental results for static axial thrust showed reasonable agreement around pump best efficiency flow rate. The pump intake sump test apparatus，in which both an air-entrained surface vortex and a submerged vortex will occur，was employed and the axial thrust was measured. The level of axial thrust is dependent on the pump intake sump water level. The dynamic axial thrust begins to increase due to the occurrence of a full air core vortex to intake. When submerged as well as full air core continuous vortices occur，the axial thrust and the fluctuation of total pump head become abruptly large. The fluctuation of axial thrust becomes the highest when the impeller sucks the air-drawing large vortex imposing a pressure fluctuation which generates not only a rotational speed but also nZ vane passing and low frequency components.

Experimental Investigation on Characteristics of Flow Instabilities in Centrifugal Pump Impeller under Part-Load Conditions

This paper presents an experimental investigation of large-scale flow-field instabilities in a centrifugal pump impeller of low specific speed. Measurements of pump hydraulic performance and flow-field in the impeller passages were made with a hydraulic test rig and a Particle Image Velocimetry (PIV) system separately. Analyses of Q-H data and flow structures in the impeller passages were performed. Results showed that an unstable area existed in the range from 0.1QBEP to 0.6QBEP and had a close relationship with vortices in the impeller passages. With decreasing of flow rates, vortices experienced onset to expansion from 0.6QBEP to 0.1QBEP in visualization. Vu2/u2 was directly influenced by vortices between 0.1QBEP and 0.6QBEP; Vu/u2 and Vm/u2 were significantly influenced by vortices from pressure side to the middle; however the slight impact was observed from the middle to suction side. Thus the experimental results could provide important evidence for the influence of flow instabilities on pump hydraulic performance.

Effects of blade rotation angle deviations on mixed-flow pump hydraulic performance

By model test and numerical simulation, this paper analyzed the effects of different blades with varying rotation angle deviations on the hydraulic performance of a mixed-flow pump. It was found that when some blades had rotation angle deviations, the hydraulic performance curves of the mixed-flow pump would move. With a positive deviation, the curves moved towards the large flow rate; with a negative deviation, the curves moved towards the small flow rate. When some blades had rotation angle deviations, the symmetry and uniformity of the pressure distribution inside the mixed-flow pump flow passage both decreased; the larger the deviation, the greater the decrease. When a single blade had a large rotation angle deviation, a rather clear low pressure area was formed, lowering the cavitation performance. When two adjacent blades changed simultaneously, under the small flow rate condition, adverse pressure gradient and flow separation occurred in the flow field, and a hump appeared in the head curve and the operation stability of the mixed-flow pump dropped significantly. Near the best efficiency point (BEP), the simultaneous change of two alternate blades produced a more significant change of pressure in the flow passage, with an even larger area. Compared to the effect of two adjacent blades, two alternate blades, when changed simultaneously, made the mixed-flow pump slightly less efficient, but with a flatter efficiency curve and relatively wider high efficiency area. By fitting the test results, a functional relation among the BEP of the mixed-flow pump Q BEP, the number of deviated blades N, and blade rotation angle deviation α was established, thus realizing an effective prediction of the BEP of the mixed-flow pump when blade rotation angles have deviations.

The Impeller Improvement of the Centrifugal Pump Based on BVF Diagnostic Method

Selecting one IS 150-125-250 centrifugal pump as reference model, impeller with 3D blades has been designed using two-dimensional theory. Numerical simulations using Reynolds averaged N-S equations with a RNG k-ε two-equation turbulence model and log-law wall function are used to estimate the hydraulic performance of pump and obtain BVF distributions on impeller blade pressure surfaces and suction surfaces. The results show that, compared with IS150-125-250 pump, the designed one shows better performance in a wide operation range with the maximal efficiency 2.8% increase. With the help of boundary vorticity flux diagnostic, further improvement is realized. Local defect areas on blade surfaces are identified and inlet blade angle distribution modification and wrapping angle change of designed impeller are carried out on local defect areas. The vortices that exist in designed impeller disappear after modification and it flows more smoothly in the modified impeller with slight hydraulic performance improvement than in the original designed one. BVF diagnostic can be further embedded in optimal design method to perform an automatic optimal design without manual trial-and-error procedures.

Numberical Simulation of Labyrinth Screw Pump with Separated Structure by Fluent

3D model and grid was conducted in Gambit,while single-phase flow field in the pump was simulated in CFD code-Fluent,by means of multiple reference frame (MRF) method, Renormalization group k-ε two-equation turbulence model (RNG k-εmodel) and Semi-Implicit Method for Pressure-Linked Equations (SIMPLEC) algorithm. Aim at problems generated by pump body such as body length limitation on pressure increasing, three new structure of labyrinth screw pumps,rotor separated LSP,stator separated LSP and rotor stator all separated LSP, were put forward in this paper.The analytical results got by contrasted pump hydraulic performance of different structure models indicated that pressure increasing magnitude and pressure increasing rate of the three separated pumps is larger compared to the unseparated pumps,and the conclusion was achieved that pump performance can be optimized through separating rotor or stator into sections by making ring slots on screw body.

Numerical and Experimental Study of Axial Force and Hydraulic Performance in a Deep-Well Centrifugal Pump With Different Impeller Rear Shroud Radius

A multistage deep-well centrifugal pump (DCP) with different impeller rear shroud radius have been investigated both numerically and experimentally under multiconditons, which aims at studying the influence of impeller rear shroud radius to the axial force and pump hydraulic performance. During this study, a two-stage DCP equipped with three different impellers was simulated employing the commercial computational fluid dynamics (CFD) software ANYSY-Fluent to solve the Navier-Stokes equations for three-dimensional steady flow. High-quality structured grids were meshed on the whole computational domain. Test results were acquired by prototype experiments, and then compared with the predicted pump performance and axial force. The static pressure distribution in the pump passage obtained by numerical simulation was analyzed. The results indicated that the appropriate impeller rear shroud radius could improve the pump performance and lower the axial force significantly.

The Oil Temperature Controlling of Hydraulic Pump Performance Test-System

In the testing of the oil temperature controlling of hydraulic pump performance test-system, the changing of oil temperature bring the testing accuracy decrease, so it can influence nicety and contrast of test-bed. A computer device of oil temperature real time control are designed. The result of control achieve B level accuracy of international and guild. The software of computer is minimum variance correcting by oneself.

Fault Prediction Based on Data Fusion

The performance of hydraulic pump will directly affect the normal work of the entire hydraulic system, so it is essential for its condition monitoring and fault prediction. It collects vibration signal and pressure signal for hydraulic pump which degenerates from the normal state to loose slipper state. It uses wavelet packet to decompose energy of frequency area in order to get fault feature vectors and builds support vector machine prediction model for feature vectors, then predicts possible fault by D-S evidence theory. The experiment results show that the method can effectively predict fault for hydraulic pump.

Parametrization of blade leading and trailing edge positions and its influence on mixed-flow pump performance

Based on the three-dimensional design platform, this article conducted parametrization of blade leading and trailing edge positions, and analyzed the influence of different position parameters on mixed-flow pump hydraulic performance and internal flow with model test and numerical simulation. The results showed that the hydraulic efficiency η of a mixed-flow pump increased slightly when the position parameter θh of the blade leading edge on the hub increased, and η increased significantly when the position parameter θt of the blade leading and trailing edge positions on the shroud increased. However, with θt increasing, the growth rate of η decreased. Numerical simulation has shown that by selecting a proper value of θt, the impeller energy conversion capacity can be effectively improved, and the distributions of static pressure and total energy can be more uniform in the flow passage. Meanwhile, with θt increasing, blade angle on the blade trailing edge decreased. Correspondingly, the absolute velocity in the outlet zone decreased, and the hydraulic loss in the outlet zone also decreased, which is beneficial to improving hydraulic efficiency of the mixed-flow pump. Within the value range of 7–9°, with different combinations of position parameter θt1 of the blade leading edge on the shroud and position parameter θt2 of the blade trailing edge on the shroud, the mixed-flow pump hydraulic efficiency η and blade wrap angle ϕ show a linear positive correlation, suggesting that an increase in ϕ could significantly improve impeller energy conversion capacity. Compared to θt1, θt2 has a more significant influence on ϕ and η. Thus, the value of θt2 should be carefully attended to during design process.

Research on Impeller Blade Style of Stamping and Welding Multistage Centrifugal Pump

Impact of vane curve on hydraulic performance of the DQ100-64-22 stamping pump was researched by CFD simulation and experiments. The research results show that processing fillet at the connecting section of space blade and shafts only generates minor influence on the pump performance，but it can decrease incidence losses of the inlet flow. The cylindrical blade type has great influence on both inner flow field and hydraulic performance of pump in the high flow rate conditions. The research can supply a good support for the vane curve design and manufacture of stamping and welding multistage centrifugal pumps.

Virtual Iinstrument Based Test–Bed for the Hydraulic Pump Performance Measurement System

The computer-aided test is very important in testing the characteristic of the hydraulic pump system; it can make the system respond rapidly, get the result more accuracy and have the visual results. In this paper, the LabVIEW software is used in the hydraulic pump performance measurement system; all the instruments and measurement parameters needed by the system were designed based on LabVIEW. For example, the signal gathering; the data processing, save and display; the curve drawing and the error processing, and so on. Two basic and important experiments are carried to validate the test system, and the results show that the measurement system can be used in laboratories and industry occasions. The measurement system can reduce some instruments, short down the test cost and the test time greatly. The software programmed by the pattern of modularization, that makes programs has a clear structure, easy to be read, maintain and expand its function.

Computational Fluid Dynamics and Experimental Characterization of the Pediatric Pump-Lung.

The pediatric pump-lung (PediPL) is a miniaturized integrated pediatric pump-oxygenator specifically designed for cardiac or cardiopulmonary support for patients weighing 5-20 kg to allow mobility and extended use for 30 days. The PediPL incorporates a magnetically levitated impeller with uniquely configured hollow fiber membranes into a single unit capable of performing both pumping and gas exchange. A combined computational and experimental study was conducted to characterize the functional and hemocompatibility performances of this newly developed device. The three-dimensional flow features of the PediPL and its hemolytic characteristics were analyzed using computational fluid dynamics based modeling. The oxygen exchange was modeled based on a convection-diffusion-reaction process. The hollow fiber membranes were modeled as a porous medium which incorporates the flow resistance in the bundle by an added momentum sink term. The pumping function was evaluated for the required range of operating conditions (0.5-2.5 L/min and 1000-3000 rpm). The blood damage potentials were further analyzed in terms of flow and shear stress fields, and the calculations of hemolysis index. In parallel, the hydraulic pump performance, oxygen transfer and hemolysis level were quantified experimentally. Based on the computational and experimental results, the PediPL device is found to be functional to provide necessary oxygen transfer and blood pumping requirements for the pediatric patients. Smooth blood flow characteristics and low blood damage potential were observed in the entire device. The in-vitro tests further confirmed that the PediPL can provide adequate blood pumping and oxygen transfer over the range of intended operating conditions with acceptable hemolytic performance. The rated flow rate for oxygenation is 2.5 L/min. The normalized index of hemolysis is 0.065 g/100L at 1.0 L/min and 3000 rpm.

Testing System Design for Multi-Circuit Gear Pump

Multi-circuit gear pump working performance cannot be affected by load, and it outputs the same amount of oil in every port, which can provide static pressure supporting for the guide ways of machine tool. The test schematic is designed with the destination of testing multi-circuit gear pump hydraulic performance. Test equipment and hydraulic oil are selected scientifically and reasonably based on multi-circuit gear pump performance parameters which have been designed, and then hydraulic system is installed in order to execute performance testing.

In Vivo Evaluation of Zirconia Ceramic in the DexAide Right Ventricular Assist Device Journal Bearing

Zirconia is a ceramic with material properties ideal for journal bearing applications. The purpose of this study was to evaluate the use of zirconium oxide (zirconia) as a blood journal bearing material in the DexAide right ventricular assist device. Zirconia ceramic was used instead of titanium to manufacture the DexAide stator housing without changing the stator geometry or the remaining pump hardware components. Pump hydraulic performance, journal bearing reliability, biocompatibility, and motor efficiency data of the zirconia stator were evaluated in six chronic bovine experiments for 14-91 days and compared with data from chronic experiments using the titanium stator. Pump performance data including average in vivo pump flows and speeds using a zirconia stator showed no statistically significant difference to the average values for 16 prior titanium stator in vivo studies, with the exception of a 19% reduction in power consumption. Indices of hemolysis were comparable for both stator types. Results of coagulation assays and platelet aggregation tests for the zirconia stator implants showed no device-induced increase in platelet activation. Postexplant evaluation of the zirconia journal bearing surfaces showed no biologic deposition in any of the implants. In conclusion, zirconia ceramic can be used as a hemocompatible material to improve motor efficiency while maintaining hydraulic performance in a blood journal bearing application.

A novel shaft-less double suction mini pump

A novel double suction shaft-less mini pump was developed for heat control of small energy systems in this study. The mini pump impeller with an exit diameter of 40 mm was combined with the motor rotor supported by the hybrid dynamic bearing. The specific speed of the pump was 125 min−1 m3 min−1 m. The hydraulic performance of the pump was investigated experiment- tally under four rotational speeds. From the test results, it was recognized that the pump could provide a flow discharge of 5 L/min and head of 1.5 m, which are applicable for the heat control system of a 3 kW fuel cell. A three-dimensional turbulent flow simulation in the pump was also conducted near the design point. The numerical results showed that the average hydraulic performance of the mini pump was predicted reasonably. From the internal flow simulation, it was revealed that the favorable inflow condition upstream of impeller inlet could be attained by applying the double suction shaft-less design for the mini pump.

Use of Zirconia ceramic in the DexAide right ventricular assist device blood journal bearing

Objective: To evaluate the effects of replacing the titanium (Ti)stator housing in the DexAide right ventricular assist device with one fabricated from biocompatible Zirconia oxide(Zr)ceramic. Methods: Pump hydraulic performance,journal bearing reliability,biocompatibility,and motor efficiency of the Zr stator were evaluated in vitro and in vivo (4 chronic bovine experiments) and compared with those using the Ti stator. Results: Compared with the Ti stator,the Zr stator showed increased battery life by 38% from 8 hours and 55 minutes on fully charged batteries at 2,500 rpm and 5.0 L/min to 12 hours and 20 minutes.In vitro hydraulic performance was unchanged with the exception of a 20% decrease in power consumption when using the Zr stator. Average in vivo pump flows and speeds using a Zr stator were comparable to the average values for 14 prior Ti stator in vivo studies with the exception of a 19% reduction in power consumption.Hemolysis and platelet aggregation tests were comparable for both stator types.Post explant evaluation of the Zr blood journal bearing surfaces showed no biologic deposition or signs of wear indicating favorable biocompatibility. Conclusions: The results of these studies showed that Zr ceramic can be used as a hemocompatible material to improve motor efficiency while maintaining hydraulic performance in a blood journal bearing application.