Abstract

The vibration performance of centrifugal impellers is important for pumps and hydraulic excitation is a key source of vibration. The complex internal secondary flow in the centrifugal impeller brings degradation on both hydraulic and vibration performances. An attempt of optimization by controlling the thickness distribution of centrifugal impeller blade is given to repress the internal secondary flow and alleviating vibration. The vibration performances of the impellers are investigated numerically and experimentally. Meanwhile, further study on the mechanism of the influence of the thickness distribution optimization on vibration is conducted. There is a relative velocity gradient from suction side (SS) to pressure side (PS), causing non-uniformity of energy distribution. By means of thickness distribution optimization, the impeller blade angle on the PS and SS along the blade-aligned (BA) streamwise location is respectively modified and therefore the flow field can be improved. What's more, experimental research upon the prototype impeller (PRT) and optimized impeller (OPT) is also complemented to support the CFD results. The hydraulic performance of impeller OPT meets the requirement of the designed parameter. The vibration acceleration data of impeller PRT and OPT at pump base is gathered in experiment. The vibration acceleration at blade passing frequency is reduced from 0.105 m/s2 to 0.026 m/s2, with a reduction ratio of 75.2%. The experiment results show that the hydraulic performance of the impellers basically agree with the CFD results and the vibration data also proves the better vibration performance of the optimized impeller.

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