有限催化对返回舱气动热环境影响

Finite-rate surface catalysis effects on aero-heating environment of a reentry capsule

基于给定催化效率的方法,发展了包含离子组分的有限催化边界条件,并结合多组分化学非平衡N-S方程数值求解,建立了有限催化条件下的高超声速飞行器气动热环境计算方法。采用不同催化效率对返回舱外形典型再入工况气动热环境开展了计算分析,研究了壁面有限催化对该返回舱气动热环境的影响规律。结果表明:壁面催化效率对返回舱气动加热影响显著,采用低催化效率壁面材料可有效缓和返回舱气动热环境;扩散热流相对传导热流对壁面催化效率更加敏感,是影响气动热的主要机制,但热流并不随催化效率增加而线性增大;壁面有限催化对气动热的影响不仅与壁面材料催化效率有关,也与流场离解电离程度、壁面密度、温度等当地流动参数相关。

Numerical method for predicting the aero-heating environment of hypersonic vehicles with catalytic surface is developed by solving the multispecies chemical nonequilibrium Navier-Stokes equations.A catalytic-efficiency-based finite-rate catalytic boundary condition including ionic species is proposed to model the surface catalysis.Then numerical simulations with different surface catalytic efficiencies of a reentry capsule are conducted to investigate the influence of finite-rate surface catalysis on aero-heating.Results show that the surface catalytic efficiency plays a significant role in aero-heating,and low catalytic efficiency material should be adopted to ease the aero-heating environment.Compared with the convective heat flux,the diffusive heat flux is more sensitive to the catalytic efficiency,and is the main mechanism of the nonlinear increase in aero-heating.Beside the surface catalytic efficiency,the influence of surface catalysis on aero-heating also depends on the local flow characteristics,such as degree of dissociation and ionization,surface density,temperature,and so on.