Analysis of thermochemical ablation and mechanical erosion of C/C composites based on macro-meso-scale numerical simulation methods

Carbon/carbon (C/C) composites as one of thermal protection materials for hypersonic vehicles are subjected to extreme thermochemical ablation and mechanical erosion, and the characterization and evaluation of thermal protection properties of C/C composites is a critical and challenging task. An ablation model for the analysis of thermal protection properties of C/C composites systematically considering thermochemical ablation and mechanical erosion is established. Firstly, a heterogeneous surface roughness model and a mechanical erosion criterion on mesoscale are adopted and numerically solved by finite volume method and piecewise linear interface calculation algorithm. Mechanical erosion factor is obtained by comparing the mass loss rates with and without mechanical erosion. Then, the thermochemical ablation model of C/C composites on macroscale is built based on finite element method, which contains element mass conservation equation, thermochemical equilibrium theory, and the multi-physical field analysis of heat and mass transfer. The mechanical erosion factor is introduced into the macroscopic ablation analysis of C/C composites. The ablation model of C/C composites is validated by comparing with experimental and analytical results. Finally, the results of mechanical erosion factor of C/C composites are calculated and discussed, and the temperature field and exterior ablation morphology of nose tip of hypersonic vehicle are analyzed. It shows that the ablation model can well analyze the thermal protection properties of C/C composites in the thermal protection system of hypersonic vehicle under the consideration of thermochemical ablation and mechanical erosion.