离心泵瞬态空化流动压力脉动及空泡形态

Pressure Fluctuation and Cavity Pattern of Transient Cavitation Flow in a Centrifugal Pump

基于RNG k-ε湍流模型和改进的质量输运空化模型,数值模拟了离心泵内瞬态空化流动。数值计算得到的离心泵扬程随有效空化余量的变化与试验结果吻合较好,验证了数值模型和计算方法的准确性。在离心泵叶轮内叶片吸力面、流道中间及叶片压力面布置监测点,分析叶轮内压力脉动特性及瞬态空泡形态。结果表明:叶轮内压力脉动主频为叶轮转频及其谐频;在叶片吸力面,叶轮内压力脉动最大幅值在距进口4/5处最大,流道中间及叶片压力面,压力脉动最大幅值由进口至出口渐渐增大,在出口处最大。叶轮流道内空泡随时间经历发展、断裂、溃灭的周期性变化过程;空泡连续的大尺度再生和溃灭造成压力脉动幅值增大,附着型空泡导致压力脉动幅值减小。

The transient cavitation flows in a centrifugal pump are numerically simulated by using the modified mass transport cavitation model and RNG k-6 turbulence model. The calculated variation of pump heads is in good agreement with the experiment data. The results indicate that the numerical model and method can accurately predict the cavitation flows in a centrifugal pump. The characteristics of pressure fluctuation and transient cavity pattern are analyzed. The dominant frequencies of pressure fluctuations in impellers include the impeller rotating frequency （fi） and its harmonic frequency. The maximum amplitude of pressure fluctuation reaches the largest value at the 4/5 length of the blade suction side from the blade inlet side. From the impeller inlet to outlet, the maximum amplitude of pressure fluctuation in flow passage and blade pressure side gradually increases; the cavity in impellers is developing, breaking and collapsing with time; the pressure fluctuation amplitude is increasing for large scale regeneration and collapsing of the cavity, and is decreasing for the attached cavity.