Numerical study of the coupled effects of carbon-based material ablation and aerothermodynamics

This study investigates the coupled interaction between carbon-based material ablation and hypersonic aerothermodynamics using a thermochemical nonequilibrium CFD framework. To address the lack of detailed comparative analyses of ablation effects on aerodynamic heating under different operating conditions, non-uniform wall-temperature distributions are considered under representative freestream conditions, together with matched non-ablating reference cases. The results show that the trends in ablation mass flux and wall heat flux differ markedly between oxidation-dominated and sublimation-dominated regimes. In the oxidation-dominated regime, the ablation mass flux is nearly insensitive to wall temperature, and its increase with freestream density becomes progressively weaker at higher densities. As wall temperature rises, sublimation becomes dominant. Sublimation products consume oxidizers and suppress oxidation; at high sublimation rates, excess products are convected downstream and further inhibit sublimation. In contrast to oxidation, the sublimation mass flux increases sharply with wall temperature and becomes larger as freestream density decreases. The aerothermal response also differs fundamentally: oxidation induces only minor net changes in wall heat flux because injection cooling is largely offset by exothermic chemistry, whereas sublimation markedly reduces both the heat of reaction flux and the conductive heat flux, thereby substantially alleviating heating and potentially shifting the peak heat flux downstream.