高超声速气动热数值计算壁面网格准则

Grid generation criterions in hypersonic aeroheating computations

首先对高超声速气动热数值模拟中的3种壁面法向网格准则(平均自由程(MFP)、自由来流参数网格雷诺数和壁面参数网格雷诺数准则)进行了分析.随后,提出了壁面参数预估方法,使得壁面参数网格雷诺数和MFP两种准则无需进行试算即可直接预估壁面法向网格尺度.其次,运用提出的壁面参数预估方法结合不同网格准则,在同一实验条件下确定多个壁面法向网格尺度,通过与实验数据对比研究各网格准则确定的壁面法向网格尺度是否满足热环境模拟精度要求,并对提出的壁面参数预估方法进行验证.最后,开展了高超声速二维完全气体及真实气体效应算例、三维钝双锥算例的数值模拟.研究表明,壁面参数预估方法是可靠的;自由来流参数网格雷诺数准则随来流静温变化所确定的网格尺度变化趋势与物理推理相悖;基于壁面参数网格雷诺数和MFP两种准则主要受壁面温度影响,其在同一条件下所确定的网格尺度基本一致,并满足热环境模拟的精度要求.

Three wall normal grid generation criterions in hypersonic aeroheating computations are analyzed, including mean free path （MFP） , and cell Reynolds number based on freestream parameters and wall parameters respectively. A wall parameter prediction method is proposed to avoid trial computations when MFP and cell Reynolds number based on wall parameters criterions are used. The proposed method is utilized and combined with different grid generation criterions to generate several grids. A comparison with the experimental data is conducted to test if the wall normal mesh size determined by the grid criterions can satisfy the precision requirement of thermal environment simulation, and also to verify the wall parameter prediction method pro- posed. Numerical simulations of two-dimensional cylinder with perfect and real gas effects, and three-dimensional blunt bicone are carried out. It can be concluded that the wall parameter prediction method is reliable, the criterion of the cell Reynolds number based on freestream parameters would amplify the wall grid scale with the increase of the freestream temperature, both MFP and cell Reynolds number based on wall parameters are influenced by wall temperature rather than by freestream temperature, and the grid scale determined by these two criterions are consistent and can satisfy the precision requirements of hypersonic aeroheating computations.