全机绕流Euler方程多重网格分区计算方法

全机三维复杂形状绕流数值求解只能采用分区求解的方法,本文采用可压缩Euler方程有限体积方法以及多重网格分区方法对流场进行分区计算。数值方法采用改进的van Leer迎风型矢通量分裂格式和MUSCL方法,基于有限体积方法和迎风型矢通量分裂方法,建立一套处理子区域内分界面的耦合条件。各个子区域之间采用显式耦合条件,区域内部采用隐式格式和局部时间步长等,以加快收敛速度。计算结果飞机表面压力分布等气动力特性与实验值进行了比较,二者基本吻合。计算结果表明采用分析“V”型多重网格方法,能提高计算效率,加快收敛速度达到接近一个量级。根据全机数值计算结果和可视化结果讨论了流场背风区域旋涡的形成过程。

Multi-Block and Multi-Grid Computational Methods of Aircraft Flow Euler Equations

Numerical solution of three-dimensional Euler equations using multi-block and multi-grid computational methods was studied with finite volume method. Modified Van Leer upwind flux-vector-splitting method and MUSCL scheme were used. The conservative multi-block zonal boundary conditions from the flux-vector-splitting method and propagating characteristic theory of hyperbolic equations using finite volume methods were derived. The explicit zonal interface boundary conditions were used for multi-block zonal message transformation. The "V"-type multi-grid method was introduced to accelerate the convergence speed while the implicit time marching scheme was used to accelerate calculation convergence. Numerical results show that the multi-grid technology can raise the convergence speed by nearly one order of magnitude. The numerical and experimental results of aerodynamic characteristics, such as lift and drag agree very well at moderate high angle of attack. The numerical visualization of three-dimensional vortex flow shows that a vortex roll-up separated from leading edge can be seen.