基于当地流动特征的Schnerr-Sauer空化模型改进研究

为消除空化模型中人为确定的经验参数对数值模拟结果的影响，引入当地流动特征对考虑非冷凝气体的Schnerr-Sauer空化模型进行修正.采用Mixture多相流模型及Realizable k-ε湍流模型，对二维NACA0009 MOD水翼的定常空化进行了数值模拟，空化数范围为0.75~0.90.将数值模拟结果与已有实验结果进行对比表明:对于考虑了非冷凝气体的Schnerr-Sauer空化模型，在引入当地流动特征修正前，非冷凝气体数密度n的取值对数值模拟结果影响较大，非冷凝气体直径d_nuc的取值对模拟结果的影响较小；在引入剪切应变率修正后，空化模型中的参数n的取值对数值模拟的结果不再有显著影响.同时，该修正方法提高了考虑非冷凝气体的Schnerr-Sauer空化模型的准确性，准确地预测了空穴造成压力梯度突变的位置. 

A Modified Schnerr-Sauer Cavitation Model with Local Flow Properties

In order to eliminate artificial choosing empirical parameters' influence on numerical simulation, the Schnerr-Sauer cavitation model, considering the effect of non-condensable gas, was modified based on the local flow properties. Choosing Mixture multiphase model and Realizable k-ε turbulence model, the numerical simulation was carried out for steady cavitating flows over a 2D NACA0009 MOD hydrofoil by means of the modified and original Schnerr-Sauer model with the cavitation number 0.75 to 0.90,and the simulation results were compared with experimental data. The results show that, for the Schnerr-Sauer cavitation model, considering the effect of non-condensable gas, the density n of non-condensable gas has a great influence on the simulation results before modifying, while the diameter d_nuc has little influence. The modified cavitation model which considers local shear strain rate can effectively eliminate the obvious effect of the empirical parameters and can improve the accuracy of numerical simulation. The saltation location of cavitation pressure gradient can be accurately predicted by the modified model.