• International Journal of Fluid Machinery and Systems
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• v.1 no.1
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• pp.57-63
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• 2008

To optimize the stationary components in the multistage centrifugal pump, the effects of the return vane profile on the performances of the multistage centrifugal pump were investigated experimentally, taking account of the inlet flow conditions for the next stage impeller. The return vane, whose trailing edge is set at the outer wall position of the annular channel downstream of the vane and which discharges the swirl-less flow, gives better pump performances. By equipping such return vane with the swirl stop set from the trailing edge to the main shaft position, the unstable head characteristics can be also suppressed successfully at the lower discharge. Taking the pump performances and the flow conditions into account, the impeller blade was modified so as to get the shock-free condition where the incidence angle is zero at the inlet.

• The KSFM Journal of Fluid Machinery
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• v.14 no.6
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• pp.54-60
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• 2011

This paper presents the steady-state performance analysis of the first stage of a multistage centrifugal pump, composed of a shrouded-impeller, a vaned-diffuser and a return-channel, using the commercially available computational fluid dynamics (CFD) code, ANSYS CFX. The detailed flow fields in the vaned-diffuser with outlet in its side wall and the return-channel are investigated by the CFD code adopted in the present study. The effect of the vaned-diffuser with a downstream crossover bend and the corresponding return-channel on the overall hydrodynamic performance of the first stage pump has also been demonstrated over the normal operating conditions. The predicted hydrodynamics for the diffusing components herein could provide useful information to match the inlet blade angle of the next stage impeller for improving the multistage pump performances.

• Advances in Computational Design
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• v.6 no.1
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• pp.43-53
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• 2021

Multi-stage pumps are the most popular pumps among various kinds of centrifugal pumps. Athorough review of different kinds of literature has led to the conclusion that there is a desperate need to increase the performance of the multi-stage centrifugal pump. Many investigators have put their efforts to increase the pump performance and also the work is being projected on various aspects of pump performance variables. To improve the multistage centrifugal pump performance by investigation, modification, and analysis many works of literature are available. For analysis, many researchers used the Navier-Stokes solver to create the three-dimensional unsteady turbulent flow numerical model with the standard k-ε turbulent equation. This paper mainly focuses on research related to the multi-stage centrifugal pump.

• International Journal of Fluid Machinery and Systems
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• v.1 no.1
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• pp.86-91
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• 2008

The effects of the diffuser vane on the performances of the multistage centrifugal pump were investigated experimentally, taking account of the interactions among the diffuser vane, the return vane, and the next stage impeller. It is very important to match well the diffuser vane with the return vane, for improving the hydraulic efficiency of the pump. The efficiency may be more improved by making the cross-sectional area of the channel from the diffuser vane outlet to the return vane inlet larger, as much as possible.

• International Journal of Fluid Machinery and Systems
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• v.9 no.2
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• pp.107-118
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• 2016

This paper focuses on the single stage and multistage performance characteristics of centrifugal mixed flow submersible borewell pump. This study reveals that the performance of single stage pump is higher than that of multistage pumps. The head, input power and efficiency of single stage pump are higher than the per stage head, per stage input power and efficiency of multistage pumps. This study is divided into three parts. In the first part, five prototype pumps were made in single stage and multistage construction and the performance tests were conducted. In the second part, numerical validation has been done for different turbulence models and grid sizes. k-Omega SST model has been selected for the performance simulation and was validated with the performance of the test pump with static pressure tappings. In the third part, single and three stage pump performance were simulated numerically and compared with experimental results. The detailed analysis of pressure and velocity distributions reveals the difference in performance of single and three stage pump, due to non-uniform flow and difference in averaged flow velocities at the subsequent impeller inlets except the 1st stage impeller inlet.

• 유체기계공업학회:학술대회논문집
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• 2005.12a
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• pp.359-364
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• 2005

Centrifugal pump shows the strongest secondary flow. Wake is formed near pressure surface close to hub at impeller exit for centrifugal pump impeller. Pressure gradient drives secondary flow in the inducer region, while in the remaining region the following sources drive together: > Pressure gradient > Coriolis force Low-momentum fluid near suction surface hub moves toward pressure surface hub in mixed-flow pump impeller. Tip leakage vortex dominate secondary flow in axial-flow pump impeller. Tip leakage vortex dominate secondary flow in axial-flow in axial-flow pump impeller

• The KSFM Journal of Fluid Machinery
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• v.18 no.1
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• pp.65-71
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• 2015

The purpose of this study is to investigate cavitating flow of the multistage centrifugal pump. Cavitation is observed in the impeller leading edge and trailing edge of the suction area. Head coefficients are measured under different flow operating conditions. The Rayleigh-Plesset cavitation model is adapted to predict the occurrence of cavitation in the pump. The two-phase gas-liquid homogeneous CFD method is used to analyze the centrifugal pump performances with two equation transport turbulence model. The simulations are carried out with three different flow coefficients such as 0.103, 0.128 and 0.154. The occurrence of cavitation described according to water vapor volume fraction. The head versus NPSH (Net Positive Suction Head) also measured using different flow coefficients. Development of cavitation in the centrifugal pump impellerI is discussed. It is showed that the simulation represents the head drop about 3%.

• International Journal of Fluid Machinery and Systems
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• v.7 no.4
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• pp.142-150
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• 2014

In the cardiopulmonary support system with an ECMO (extracorporeal membrane oxygenation), a higher pump head is demanded for a blood pump. In order to realize a blood pump with higher pump head, higher anti-hemolysis and thrombosis performances, a study on the development of unprecedented multistage blood pump was conducted. In consideration of the application of the blood pump for pediatric patients, a miniature two-stage centrifugal blood pump with the impeller's diameter of 40mm was designed and the performance was examined in experiments and computations. Some useful knowledge for a design of the blood pump with higher anti-hemolysis and thrombosis performances was obtained.

• The KSFM Journal of Fluid Machinery
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• v.18 no.2
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• pp.67-72
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• 2015

The purpose of this study is to achieve energy saving effect of inverter driving multistage centrifugal pump. For determining the operation points in the pump system, the system curves should be obtained experimentally. To get the system curves, three pumps combined in parallel and one pump operated with different rotational speeds. But for variable speed pump system, energy saving rates can not be evaluated from operation efficiencies. That is why operation efficiencies, system curves, duty cycles, and input powers of the pump system were measured by the constructed experimental apparatus. The duty cycle segmented into different flow rates and weighting the average value for each segment by the interval time. The system was operated with two different periods. The mean duty cycles were collected from apartment and found that the system operated at 40% and at 50% or below capacity. Measured energy saving rate was 58.16%. Estimating method of energy saving rate could be more effective operation index than that of operation efficiency.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.35 no.9
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• pp.875-882
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• 2011

In the present study, the imbalance in the axial-thrust and variation in the volumetric efficiency that occurred during the trimming of impeller diameter were investigated. The present study was focused on low-specific-speed multistage centrifugal pumps with a balancing piston as the balancing mechanism. The effects of impeller trimming on the axial-thrust balance in multistage pumps with horizontal and vertical axes were compared. The results showed that impeller trimming resulted in an additional axial-thrust acting in direction of pump inlet. The axial-thrust imbalance due to impeller trimming was more severe in the vertical-axis pumps than in the horizontal-axis pumps. The rate of increase in the diameter of the balancing piston, which was proportional to the rate of impeller trimming, was evaluated to maintain the axial-thrust balance. Furthermore, a simultaneous increase in the piston length and piston diameter was more effective for reducing the axial-thrust imbalance along with the volumetric efficiency drop.