湍流模型离散精度对数值模拟影响的计算分析

基于雷诺平均Navier-Stokes(RANS)方程和结构网格技术,采用五阶空间离散精度的加权紧致非线性格式(WCNS),通过改变物面法向第一层网格间距,开展了剪切应力输运(SST)两方程模型不同离散精度的数值分析。主要目的是为高阶精度格式在复杂外形上的应用提供技术支撑。计算模型包含了低速NLR 7301两段翼型和高速RAE2822翼型,研究内容主要包括湍流模型的二阶精度离散和五阶精度离散两种方式对收敛历程、边界层湍流黏性系数分布、边界层速度分布、压力系数分布以及气动特性的影响。在与试验数据对比的基础上,计算结果表明:对于不同的第一层物面法向网格间距,湍流模型离散精度对低速绕流计算结果有比较明显的影响,对于高速小迎角附着流动计算结果影响不明显;相对于湍流模型二阶精度离散,湍流模型高阶精度离散网格敏感性较弱,具有更高的数值模拟精度,但收敛性略差。

Numerical analysis of the effect of discrete accuracy of turbulence model on numerical simulation

Based on the Reynolds-averaged Navier-Stokes(RANS) and structured grid technology, the effect of different discrete methods of shear stress transport (SST) turbulence model on simulation results is analyzed numerically on various grids of different first thickness cells in normal direction with fifth-order weighted compact nonlinear scheme(WCNS). The main purpose of the present work is to provide technical support for the application of high-order difference schemes in complex configurations. The models under study include low-speed NLR 7301 two-element airfoil and high-speed RAE2822 subcritical airfoil; the research work contains the influence of two-order and five-order discrete methods of the turbulence model on convergence history, the distribution of turbulent viscosity and velocity in boundary layer, pressure coefficients and aerodynamic characteristics. Compared with the experimental data, the numerical results indicate that the thickness of first cell in boundary layer and the discrete accuracy of the turbulence model affect the numerical results at low speed obviously, whereas they have little influence on those of high-speed attached flow; the high-order discrete method of the turbulence model is less sensitive to the thickness of first cell in boundary layer; higher accuracy can be obtained but suffer poorer convergence character compared with low-order discrete method of the turbulence model.