高超声速热化学非平衡对气动热环境影响

高超声速气动加热严重,考虑热化学非平衡对气动热环境影响,可以为热防护系统设计提供有效保障。采用Park和Gupta热化学非平衡模型,数值计算研究5组元(N_2,O_2,N,O,NO),17组化学反应的热化学非平衡效应对高超声速飞行器气动热环境影响,并与完全气体和热化学平衡模型进行对比分析。热化学非平衡模型流场温度及激波距离均比完全气体模型小。激波后气体密度因离解、化学反应而增大,且气体密度越大,激波距离越小,热化学平衡模型激波距离最小。完全气体和热化学平衡模型热流载荷计算值均比实验值偏大。Park和Gupta热化学非平衡模型数值计算激波距离及气动力载荷差别小。Park模型热流载荷计算值偏大,Gupta模型与实验结果相符,它可对气动热环境可靠预测。

Influence of hypersonic thermo-chemical non-equilibrium on aerodynamic thermal environments

Severe aerodynamic heating phenomenon occurs in hypersonic flight.Thermal protection system design can be effectively guided by considering the influence of hypersonic thermo-chemical non-equilibrium on aerodynamic thermal environment.Park and Gupta's thermo-chemical non-equilibrium models were used to numerically calculate the 5 species (N2,O2,N,O,NO) and 17 groups of chemical reactions,and the influence of their thermo-chemical non-equilibrium on hypersonic vehicles' aerodynamic thermal environments was compared with that obtained from perfect gas and thermo-chemical equilibrium models.In the thermo-chemical non-equilibrium model,flow field temperatures are lower and shock standoff distances are smaller than those of the perfect gas model.The larger the gas density after shock wave is,the smaller the shock standoff distance is.Therefore,the shock standoff distance of thermo-chemical equilibrium model is the smallest due to the larger gas density caused by molecular dissociation and chemical reaction effects.The numerical heat flux loads of perfect gas and thermo-chemical equilibrium models are larger than the experimental data.There are small differences between Park's and Gupta's thermo-chemical non-equilibrium model when they are used to numerically calculate the shock standoff distance and aerodynamic load.The calculated values of heat flux load of Park's model are larger,while those of Gupta's model are in good agreement with the experiments.Therefore,Gupta's model is more reliable to predict hypersonic vehicles' aerodynamic thermal environments.