部分平均Navier-Stokes方法模拟超声速斜面空腔流动

Partially averaged Navier-Stokes method for simulation of supersonic flow over a ramped-cavity

采用部分平均Navier-Stokes(PANS)方法对超声速斜面空腔流动进行了数值模拟研究,评估其对于超声速非定常湍流模拟的性能,并与雷诺平均N-S(RANS),脱体涡模拟(DES)的计算结果及实验数据进行对比.研究表明:模化湍动能比例全场可变的PANS方法预测的速度、壁面压力和摩擦力系数分布与DES的结果非常接近,都与实验值吻合得较好,优于RANS的计算结果;非定常雷诺平均N-S(URANS)计算的自由剪切层近乎为二维稳态的,而DES和PANS方法可以求解出更为丰富的流动结构;模化湍动能比例全场统一的PANS方法虽然可以求解出相比RANS更多尺度的流动结构,但在近壁区不能回归到RANS模型,预测的湍流边界层的速度型偏离对数律,后续的流动计算也偏离实验数据.

Partially averaged Navier-Stokes（PANS）model was adopted to numerically investigate the supersonic ramped-cavity flow.The objective of current study is to assess the capability of PANS method in the prediction of unsteady supersonic turbulent flow.Comparison of PANS,Reynolds averaged Navier-Stokes（RANS）and detached eddy simulation（DES）results with the available experimental data shows that：（1）velocity profiles,wallpressure and skin-friction coefficient distributions predicted by PANS model with variable unresolved-to-total ratio of kinetic energy are consistent with DES results;and（2）both of PANS results with variable unresolved-to-total ratio of kinetic energy and DES results are in good agreement with the experimental data and superior to those predicted by RANS;and（3）unsteady Raynolds averaged Navier-Stokes（URANS）model predicts two dimensional steady geometries of free shear layer,while DES and PANS resolve more abundant flow structures;and（4）PANS model with constant unresolved-to-total ratio of kinetic energy cannot return to RANS model in the near-wall region despite it can resolve more scales of motion compared with RANS;and the predicted velocity profiles of upstream turbulent boundary layer mismatch the log law,thus downstream flow simulation deviates a lot from the experiment.