高超声速连续／稀薄流自适应界面推进重叠网格方法及应用研究

摘要

When the hypersonic aircraft flies in the transitional regime,both continuum and rarefied flows appear in the flow field around the aircraft.A multi-scale adaptive advanced overset grid method is proposed to deal with such a flow problem.The whole flow field is covered by the structured and unstructured grids which are independently generated in different scales.The a-daptive hole cutting process is advanced by the cut-off value of the interface breakdown function of the continuum and rarefied flows in the structured grid.When the hole cutting process is com-pleted,the rarefied regions are computed using the unstructured DSMC method while the contin-uum regions are computed using the structured CFD method based on the N-S equations.To cou-ple the two algorithms,the flow information at the boundary between the continuum and rarefied regions is interpolated,exchanged and processed.According to the instantaneous solution of the coupled flow field,the overlapping parts of the different grids are advanced by the interface breakdown function.The feasibility and effectiveness of the present method are validated by the simulation results of the supersonic flow across a cylinder and hypersonic flow across a hollow cylinder-flare.%根据高超声速飞行器在过渡流域飞行时绕流流场具有连续流与稀薄流并存的特点，提出了一种适用于混合流场自适应界面推进的多尺度重叠网格方法。用两套独立生成不同尺度的结构网格和非结构网格覆盖整个流场。根据连续／稀薄流界面失效函数的截止值在结构网格内进行自适应“挖洞”。在挖洞后的稀薄流区利用非结构网格 DSMC 方法进行计算；在连续流区的结构网格内采用基于 N-S 方程的 CFD 算法。两种算法进行耦合计算和求解，在连续／稀薄流分界面进行流场信息的插值、交换和处理。根据流场实时耦合计算结果，利用界面失效函数自适应改变两套网格的重叠部分。最后，通过对超声速圆柱和高超声速带扩张角圆管绕流的数值模拟，验证了方法的可行性和有效性。