稀薄流热化学非平衡效应的DSMC研究

DSMC Study for the Effects of Thermochemical Nonequilibrium in Rarefied Flow

以钝体绕流驻点线流场为例，应用直接仿真蒙特卡罗法（DSMC），模拟了五组元混合气体（N2、O2、N、O、NO）中的碰憧传能松弛、离解反应、交换反应及复合反应。给出了碰撞分子各自由度间的能量交换模式及各类化学反应的选择模式。DSMC仿真结果与宏观粘性激波层方程计算结果，在飞行高度较低时基本相符，表明采用的热化学非平衡模式是令人满意的。随着飞行高度增高稀薄气体效应增大，二者在激波附近有显著差异，表明高空飞行必须考虑热化学非平衡效应和稀薄气体效应。

In this paper, the DSMC method is employed to sim-ulate energy transfer inmolecular collisions, dissociated reaction, exchange atotns reactions and recombination reactions in a fivespecie gas mixture (N2, O2, N, O, NO). Stagnation streamline flow of a Hypersonic blunt body is simulated. It has got energy transfer models among molecular degrees in collisions and chemical reactions selection models. Comparison is made between the present DSMC results of the stagnation streamline flow of a hypersonic blunt body and its viscous shock-layer calculations, and it has a good agreement at the lower altitude,which shows that models used in the paper of thermochemical nonequilibrium is satisfactory. But at the higher altitude, with the increment of nonequilibrium rare effects, there are great differences between these two results near the shock,which shows that it is necessary to consider effects of thermochemical nonequilibrium at higher altitude flight.