基于格子Boltzmann方法的非平衡气动加热算法

A non-equilibrium scheme of aerodynamic heating calculation by lattice Boltzmann method

提出了一种新的Euler与Boltzmann方程结合的气动加热数值计算方法。该方法首先采用CFD软件中的FLUENT来获取三维复杂外形边界层外缘气动参数,通过可压缩格子Boltzmann方法(LBM)的微观非平衡粒子的流动和碰撞来模拟边界层中气体热流动过程,解决了工程方法和N-S方法的适用范围不足和计算效率低下的问题。在每个LBM的流动与碰撞的过程中通过更新密度分布函数来使得宏观的速度和温度计算得以耦合。同时,对热LBM模型还做了湍流比拟和改进来扩展其应用范围。最后,通过一组高超声速气动加热试验数据证明了该结合方案的正确性和有效性,并讨论了该结合方案较其它常用方法的优缺点。

An innovative and practicable scheme combining Euler equation with lattice Boltzmann method is proposed to enhance potential applications in the aerodynamic heating prediction of hypersonic fight vehicles. In order to suit the complex three-dimensional configurations, CFD simulation based on FLUENT software is applied to obtain the aerodynamic parameters outside the boundary layer. To solve the problem of low accuracy of engineering method and to avoid the high computational cost of Navier-Stocks equation, a compressible thermal lattice Boltzmann method(LBM) is put forward to calculate the viscous effect inside the boundary layer. The thermal LBM is improved by updating density distribution function in each process of stream and collision to couple the velocity and temperature calculation. Meanwhile, an analogy between laminar flow and turbulent flow is drawn to expand application scope of this scheme. The new scheme is proved to be proper and effective by experimental data of a hypersonic vehicle, and the advantages and disadvantages are discussed by comparing with other methods of aerodynamic heating prediction.