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Effect of tip clearance on performance of low specific speed centrifugal pump with semiopen impeller |
CUI Bao-Ling1, HUANG Da-Gang1, SHI Pei-Qi1, JIN Qing-Ming2 |
(1. Laboratory of Fluid Transmission and Application, Zhejiang SciTech University, Hangzhou, Zhejiang 310018, China;
2. Zhejiang Tiande Pumps Co. Ltd., Cangnan, Zhejiang 325800, China) |
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Abstract In order to analyze the effects of tip clearance on the flow and performance of low specific speed highspeed centrifugal pump with a semiopen impeller, the inner flow field in a pump with the specific speed ns=19.3 was numerically simulated based on the Navier-Stokes equations and the Spalart-Allmaras turbulence model at the tip clearances 0.5, 1.1 and 2.5 mm. The performance of the centrifugal pump was measured as well.The results show that the flow in the impeller is improved with a bigger clearance, but the hydraulic loss caused from the circular flow in the impeller at a relatively big clearance is larger than that at a more tight clearance, so the head and efficiency were decreased with increasing tip clearance. Also, the relative velocity and static pressure of fluid in the clearance were reduced at the middle and trailing edge of blade with increasing tip clearance, especially the relative velocity. The static pressure shows a nearly linear relation to radius. The tangential and radial velocity along the axial direction in the impeller passages were lowered with increasing clearance. Comparison of the results simulated with the experimental data suggests CFD method is quite able to simulate a change in the performance due to varying tip clearance.
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Received: 25 August 2011
Published: 10 April 2012
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