高超声速压缩拐角湍流计算的收敛性分析

应用基于shear stress transport(SST)湍流模型的隐式紧耦合方法对高超声速压缩拐角流动进行了数值计算.考察了差分格式、限制器以及湍流时间步长等7个因素对湍流计算过程稳定性和收敛性的影响.结果表明:差分格式和限制器对收敛性有很大影响,总体而言耗散性越大的差分格式和限制器收敛性越好;增加湍流时间步长对收敛性影响很小;适当降低湍流变量最低限制值有利于湍流方程的收敛;增大Courant-Friedrichs-Lewy(CFL)数和隐式内迭代次数可显著加速收敛,但均存在最优值,超过最优值则加速效果不明显. 

Convergence analysis of hypersonic turbulent flow calculation at compression corner

The hypersonic compression corner flow was simulated by a fully coupled implicit method based on the shear stress transport (SST) turbulence model. Influence of seven factors including schemes, limiter functions and turbulence time steps, etc, on the robustness and convergence of calculation were evaluated. Results show that schemes and limiter functions have great influence on the convergence characteristic, and those with higher dissipation show better convergence characteristic of schemes and limiter functions. The increase of turbulent time step has little effect on convergence. The proper decrease of lower bound of turbulent variables can accelerate the convergence of turbulence equations substantially. Increase of Courant-Friedrichs-Lewy (CFL) number and inner iteration number of the lower-upper symmetric Gauss-Seidel (LU-SGS) method can accelerate the convergence greatly, while there are optimal values for different cases, the acceleration effect is not obvious if exceeding the optimal values.