高超声速飞行器表面温度分布与气动热耦合数值研究

针对高超声速飞行器热防护设计中的高温气体非平衡效应问题和气动热环境精确预测问题,基于流场的非平衡Navier-Stokes方程、表面的能量守恒方程和内部的热传导方程,考虑流场的非平衡效应、表面的热辐射效应、催化效应和烧蚀效应以及热防护层内部的热传导效应,建立了初步的表面温度分布与气动热的耦合计算方法,完善了高超声速飞行器气动物理流场计算软件(AEROPH_Flow)。在表面材料为碳-碳(C-C)条件下,对飞行高度为65km和飞行速度为8,10km/s的半球以及飞行高度为50km和飞行速度为8km/s的球锥模型,开展了表面温度分布与气动热的耦合计算,验证了计算方法和计算软件,分析了表面温度分布对气动热环境的影响。研究结果表明:表面温度分布对气动热的计算结果有较大影响,在气动热环境的预测中,不仅要考虑热化学非平衡效应和表面催化效应的影响,还要考虑表面温度分布的影响,最好是采用表面温度分布与气动热耦合计算的方法,以减小表面温度分布对气动热计算结果的影响。为此,需要发展完善非平衡流场/表面催化和烧蚀/热传导温度场(气/表/固)的计算模型、耦合求解技术和计算软件,实现对高超声速飞行器的真实飞行条件下高温气体非平衡效应和气动热环境的精确模拟。

Numerical study of coupled surface temperature distribution and aerodynamic heat for hypersonic vehicles

In order to predict precisely aeroheating and effects of high-temperature non-equilibrium gas during design the thermal protection system of hypersonic vehicles, the simulation methods of coupled surface temperature and heat transfer rate are developed based on the Navier-Stokes equations of non-equilibrium flow fields, the energy conservation equation at the surface with radiation, catalytic action and ablation, and the unsteady heat conduction equations of heat-shield, and the computational code AEROPH_Flow is perfected ,which are developed by us for numerically simulating the flow over hypersonic vehicles and predicting the aero-physical characteristics . The numerical simulation results are presented, including a semi-sphere geometries at the altitude of 65 km with the free stream velocity of 8 km/s and 10 km/s, a sphere-cone geometries at the altitude of 50 km with 8 km/s, and the polycrystalline graphite is selected as ablative material on the surface. The distributions of surface temperature and heat transfer rate are obtained and the analysis is done for the influence of the surface temperature distribution on heat transfer rate. The results show that the surface temperature distribution has a more important influence on the computational results of heat transfer rate, the factors considered in the high-precision prediction of aero-thermal environment are not only thermo-chemical non-equilibrium effect and surface catalytic effect, but also the surface temperature distributions, so the best method for high-precision prediction of aero-thermal environment is the coupling of surface temperature and heat transfer rate, and it is essential to develop perfect physical models, solving methods and numerical simulation codes of coupled non-equilibrium flow field, surface catalytic action and ablation, and heat conduction of heat-shield for the high-precision prediction of aero-thermal environment of hypersonic vehicles under the real flight condition.