2018 Volume 11 Issue 2 Pages 139-145
To improve centrifugal pump cavitation performance, the slot pulse jet pump is proposed. The slot is designed directly on the impeller shroud near the suction side of the blade leading edge. The slots are alternately blocked by the cambered prominence, which is designed at the impeller front side chamber along the circumferential direction. The leakage flow from the front side chamber flows into the slot alternately, and the pulse jet is formed near the blade inlet. Because of the strong shear, the pulse jet is more efficient than steady jet in terms of energy transmission. Based on the numerical simulation, the hydraulic performances of the slot pulse jet pumps with two different pulse frequencies are compared with the slot steady jet pump. The calculation result shows that with the increase of flow rate, the head and efficiency of the three kinds of pumps are basically the same. The cavitation performance of slot pulse jet pump is better than that of slot steady jet pump, especially for slot pulse jet pump II. The distribution of pressure difference acted on the slot appears to be jagged, and the pulse frequency is consistent with shaft frequency or its harmonic frequency. The amplitude of the pressure fluctuation on slot jet pump II is much higher than that of the slot pulse jet pump I. The vapor volume distribution in the middle span of the impeller for slot pulse jet pump is less than that of slot steady jet pump. So, the pulse jet is an effective way to further improve the cavitation performance of slot steady jet pump, and NPSHr is significantly decreased, especially at design condition.
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