不同 DDES 方法预测叶尖泄漏流动

Tip leakage flow has an essential impact on the overall performance of turbomachinery. Hybrid RANS-LES method considering both accuracy and computational cost has gradually been applied to predict complex flows in turbomachinery. DDES method is a common hybrid RANS-LES method, which combines the advantages of RANS and LES methods. The tip leakage flow has been investigated by delayed detached eddy simulation (DDES) method based on SA and SST model, respectively. Based on the LES results, the predictive capability of the two DDES methods for tip leakage flow has been evaluated. It is shown that DDES-SA underestimates the intensity of tip leakage vortex because of the excessive turbulent viscosity at the vortex core. DDES-SST method is better than DDES-SA method in predicting tip leakage flow, and its predicted value is closer to LES results, but it still has room for improvement.