摘要
对于近空间高超声速飞行器的研制,计算流体力学(CFD)起着非常重要的作用。但若流场中存在必须考虑气体稀薄效应的地方,传统的CFD就要做相应的改变,这时首先遇到的问题将是判断是否需要考虑气体的稀薄效应的判据应该是什么?[1]其次就是气体稀薄效应的影响表现在什么地方?如何在CFD中考虑这一效应?本文选取具有代表性的高超声速剪切流为研究对象,采用直接模拟Monte Carlo(DSMC)方法,对剪切强度和稀薄程度不断增强的流动,研究了分子运动速度分布函数以及剪切力的相应变化规律;找到了一个可以判别气体稀薄效应程度的无量纲参数Zh,以及传统连续介质模型下的剪切力和由DSMC所得剪切力随参数Zh的增大而出现的有规律性的差别。
Computational Fluid Dynamics(CFD)plays a very important role in the development of near space flying vehicles.However,at places where the rarefaction effect of the gas has to be considered,the conventional CFD has to be modified accordingly.Then the first question one has to answer is what would be the appropriate criterion for assessing if the rarefaction effect should be taken into consideration.And then what is the main manifestation of the rarefaction effect and how to consider this effect in CFD?In this paper,a typical hypersonic shear flow is studied by Direct Simulation Monte Carlo(DSMC).The probability density function and shear stress are investigated in details for different degrees of rarefaction and different shear strengths.A parameter Zh which can characterize the rarefaction effect is proposed,and the difference between the shear stresses obtained by the conventional continuum model and those obtained by DSMC is found to be increasing as the parameter Zh is increasing but follows a definite rule.
出处
《空气动力学学报》
CSCD
北大核心
2018年第1期4-11,共8页
Acta Aerodynamica Sinica
基金
天津大学青年人才自主科研基金支持
