• Vacuum Magazine
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• v.2 no.4
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• pp.39-46
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• 2015

After stepping into a new field of vacuum 30 years ago, our company has grown up steadily as a specialized vacuum industry, and now we can provide vacuum devices covering most of the pressure range. We are planning to put out high level dry pump like a multistage Roots pump on the market in the near future. Procedures of technology development for designing, fabricating, and testing the multistage Roots pump of 600 L/min class will be briefly reported. Core items of the technical development on the multistage Roots pump are as follows; elaborated profile design of 3-lobe rotors using an involute curve, optimization of rotor dimensions, especially for clearances and rotor width, considering the pumping speed, compression ratio and heat load, and establishment of a standardized test system. At present, the multistage Roots pump is about to come into commercialization.

• 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.

• International Journal of Fluid Machinery and Systems
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• v.3 no.4
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• pp.309-314
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• 2010

Stainless steel stamping multistage pump has become the mainstream of civil multi-stage pump. Combined with the technological features of stamping and welding pump, the studies of design for hydraulic parts of pump were come out. An $L_{18}$（$3^7$）orthogonal experiment was designed with seven factors and three values including blade inlet angle, impeller outer diameter, guide vane blade number, etc. 18 plans were designed. The two stage of whole flow field on stainless steel stamping multistage pump at design point for design was simulated by CFD. According to the test result and optimization design with experimental research, the trends of main parameters which affect hydraulic performance were got. After being manufactured and tested, the efficiency of the optimal model pump reaches 61.36% and the single head is more than 4.8 m. Compared with the standard efficiency of 53%, the design of the stainless steel stamping pump is successful. The result would be instructive to the design of Stainless steel stamping multistage pump designed by the impeller head maximum approach.

• 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.

• 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.

• 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.

• The KSFM Journal of Fluid Machinery
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• v.15 no.1
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• pp.13-20
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• 2012

A vertical-axis multistage pump with low specific speed was developed, satisfying performance requirements such as flow rate, total head, and NPSH. The developed pump was designed through conceptual design, configuration design, and performance analysis by CFD which were established in KIMM. The prototype pump's mechanical wholesomeness besides hydraulic performances were verified by running test, performance test, and reliability test.

• Journal of KSNVE
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• v.7 no.6
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• pp.1015-1023
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• 1997

Rotordynamic analysis of a multistage turbine pump using finite element method is performed to investigate the effects of seal wear on its system behavior. Stiffness and damping coefficents of the 2-axial grooved bearing are obtained as functions of rotating speed. Stiffness and damping coefficients of plane annuler seals are calculated as functions of rotating speed as well as seal clearance of seals become larger, these stiffness and damping coefficients decrease drastically so that there can be significant changes in whirl natural frequencies and damping characteristics of the pump rotor system. Although a pump is designed to operate with a sufficient seperation margin from the 1st critical speed, seal wear due to long operation may cause a sudden increase in vibration amplitude by resonance shift and reduce seal damping capability.

• International Journal of Fluid Machinery and Systems
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• v.9 no.2
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• pp.119-128
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• 2016

This work presents the numerical investigation of an unsteady cavitating flow around a balancing drum of a multistage pump. The main attention is focused on the cavitation phenomena, which occur in the rear part of the drum clearance, cause the erosion of the drum material and influence the pressure losses and the flow rate through the clearance. The one-way coupling of the URANS equations and the full Rayleigh-Plesset equation is employed to analyse the flow field as well as the dynamics of cavitating bubbles. The numerical simulations show that the erosion processes are highly influenced by shaft vibrations, namely by periodic deformations of the annular clearance in time. The calculated results are verified by erosion tests on a real pump.

• 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.