气体稀薄效应对热流计算的影响

The research and development of near-space hypersonic vehicles have attracted increasing attention. In the article "New Problems in Aerodynamics" in "Science in China", Zhou Heng and Zhang Hanxin analyzed the deficiencies of existing aerodynamics in this situation. One of them is the need to consider the possible local rarefied gas effects in the flow field, and a detailed analysis was carried out for the boundary layer of near-space hypersonic vehicles. On this basis, Chen Jie and Zhao Lei studied the gas rarefaction effect under strong shear, gave the dimensionless parameter Zh for discriminating the gas rarefaction effect, and proposed to correct the viscosity coefficient in the traditional continuum model based on the Zh parameter. In this paper, through a similar research method, the DSMC (Direct Simulation Monte Carlo) is used to study the gas rarefaction effect in the pure heat conduction problem. Through the analysis of the particle velocity distribution function, the corresponding parameter Zh_T characterizing the gas rarefaction effect is proposed, and the correction law of the thermal conductivity coefficient depending on the parameter Zh_T is obtained. Furthermore, this correction law is incorporated into the CFD (Computational Fluid Dynamics) calculation, and the accuracy of the algorithm for predicting the surface heat flux of the flow around a cylinder is verified.

临近空间高超声速飞行器的研发越来越受到关注。周恒和张涵信在《中国科学》上的《空气动力学的新问题》一文中分析了在此情况下现有的空气动力学的不足,其中之一就是需要考虑流场中可能出现的局部稀薄气体效应,并且针对临近空间高超声速飞行器边界层进行了详细的分析。陈杰和赵磊在此基础上研究了强剪切下的气体稀薄效应,给出了判别气体稀薄效应的无量纲参数Zh,并提出对传统连续介质模型中的黏性系数基于Zh参数进行修正。本文将通过类似的研究方法,采用DSMC(Direct Simulation Monte Carlo)研究纯导热问题中的气体稀薄效应,通过对粒子速度分布函数的分析提出了相应的刻画气体稀薄效应的参数Zh_T,获得了依赖参数Zh_T的导热系数修正规律,并进一步将该修正规律纳入CFD(Computational Fluid Dynamics)计算,验证了该算法对圆柱绕流问题表面热流预测的精度。