An investigation of thermochemical reaction and aerodynamic ablation model on leading edges of reentry vehicles considering rarefaction effect

High-temperature airflow interacts with the surface materials of aircraft through multiple physical and chemical processes, significantly altering the aircraft's surface morphology. This affects the evolution of flow structures as well as the aerodynamic and thermal characteristics of the surface. Accurate prediction of the ablation process during re-entry is crucial for designing thermal protection systems. However, existing studies on aerodynamic ablation primarily focus on flow fields under fixed wall temperature conditions, neglecting the impacts of complex chemical reactions and differences in wall material properties on heating and ablation morphology. This study employs the direct simulation Monte Carlo (DSMC) method, coupled with the wall energy conservation equation, and utilizes the open-source program SPARTA to analyze the aerodynamic heating process during high-speed flight. Taking a cylindrical model as an example, this study establishes separate control equations for wall heating and material ablation. By integrating gas-gas and gas-solid chemical reactions, the new ablation model is used to analyze aerodynamic ablation mechanisms of different wall materials. The results indicate that the proposed ablation model enhances the accuracy of internal energy sampling of particles post-shock and replicates existing erosion morphologies from literature. This method offers theoretical basis and data support for understanding complex thermochemical non-equilibrium phenomena under variable wall temperatures.