Cavitation has always been a difficult problem for centrifugal pumps. Cavitation will make the pump's performance decline, corrosion and destroy over flow parts, generate vibration and noise. When it is serious, pump will not run [1]. Therefore, it is necessary to study the vapor-liquid two phase flow in the cavitation of the centrifugal pump.

基于经验的传统叶轮设计需要繁琐的模型试验，大大增加了设计成本和设计周期，制约了离心泵高空化性能优化设计的进一步发展[2] 。随着计算流体动力学( CFD) 技术在水力机械内部流场计算中应用日益广泛，CFD成为优化设计的重要工具。长期以来，国内外学者采用数值模拟的方法对水泵内部空化流动进行了很多研究[5,6]，并成功预测了空化临界点[7,8,9]和离心泵叶轮内发生的多区域空化流动现象等[10,11]。如Medvitz等[12]捕捉到了离心泵在偏流量工况的能量和扬程下降特性，Coutier Delgosha等[13]采用正压状态方程对3台离心泵进行定常空化流动计算，成功获取了泵的扬程下降曲线及空泡结构。

The traditional design experience to impeller model test based on complex, greatly increasing the cost and period of design, the control of centrifugal pump of high performance optimization design and the further development of [2]. With the increasing application of computational fluid dynamics (CFD) technology in the calculation of internal flow field in hydraulic machinery, CFD has become an important tool for optimal design. For a long time, domestic and foreign scholars have done many researches on the cavitation flow inside the pump by numerical simulation. [5,6] has successfully predicted the [10,11] of cavitation critical point [7,8,9] and the multi region cavitation flow phenomenon in the impeller of centrifugal pump. For example, Medvitz and [12] captured the energy and lift drop characteristics of centrifugal pump in partial flow condition. [13] and Coutier Delgosha used the barotropic equation of state to calculate the steady cavitation flow of 3 centrifugal pumps, and successfully obtained the pump head drop curve and cavity structure.

不难看出，上述离心泵的空化研究较多集中于对外特性的预测，目前对叶轮空化性能优化改进的相关工作虽然也做了不少，但仍有待于深入研究。本文应用汽液两相流混合模型基本方程，对一台比转速为100的双吸泵叶轮内部空化性能进行数值计算和分析，并通过修改叶轮入口直径、前盖板圆弧半径及叶片进口边形状来提升叶轮空化性能，旨在给出离心泵空化流计算中叶轮改进的合理建议。

It is not difficult to see that the cavitation research of the above centrifugal pump mostly focuses on the prediction of the external characteristics. At present, there are many works related to the optimization and improvement of the impeller cavitation performance, but still need further research. The basic equations of mixed model based on two-phase flow, a specific speed of 100 double suction pump impeller cavitation performance of numerical calculation and analysis, and by modifying the entrance of the impeller diameter, the shroud radius and blade inlet edge shape to improve the cavitation performance of the impeller, aims to give reasonable suggestions of centrifugal pump cavitation flow calculation improved impeller.