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

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.