低比转速离心泵非定常空化流动特性

为了研究低比转速离心泵的空化流动特性,基于SST k-ω湍流模型和ZGB空化模型,在不同进口压力条件下对离心泵内部空化流动进行三维非定常数值模拟,研究了离心泵在发生空化时不同位置的压力脉动规律和空泡体积变化规律.结果表明:空化发生后叶轮压力脉动主频为叶频,流道进口处次频脉动幅值增长明显;空化时叶轮流道靠近叶轮出口处的压力脉动幅值增长率与叶轮流道进口处压力脉动幅值增长率相比增长更明显;空化时叶轮流道进口处的压力脉动与叶轮流道、出口及隔舌处压力脉动相比存在迟滞现象;空化过程中空泡体积的增长过程是非线性的.

Characteristics of unsteady cavitational flow in centrifugal pump with low specific speed

In order to study the characteristics of cavitational flow within centrifugal pump with low specific speed, the numerical simulation of three-dimensional unsteady cavitational flow in the pump was carried out on the basis of SST k-ω turbulence mode and ZGB cavitation mode and under different inlet pressure, and the regularity of pressure pulsation and the change of bubble volume as well at different positions in the pump were investigated when cavitation occurred. The result showed that the principal frequency of the impeller pressure pulsation would be the blade frequency, and the growth of amplitude of secondary frequency fluctuation at the inlet of impeller channel would be obvious. The growth rate of the amplitude pressure pulsation near the outlet of impeller channel would increase even more obviously when compared with that at the inlet of impeller channel. Also when cavitation took place, the pressure fluctuation at the inlet of the impeller channel would be delayed from that within the impeller, at its outlet and at its separate tongue. The growth of cavitational vapor bubble would be nonlinear.