Modeling and validation of ablative thermal response combined with microscopic heat transfer for porous ablative materials

Abstract

Porous ablative materials are the state-of-the-art thermal protection materials for extreme aerodynamic conditions during re-entry, but the precise analysis of heat transfer within microstructure and the ablative thermal response process is still a challenge. Herein, a numerical model that combines macroscopic ablative thermal response and microscopic heat transfer for porous ablative materials is presented. The microscopic heat transfer in the model is implemented through the conjugate solid and gas phases heat transfer. The model is validated by comparing the results of typical ablation cases with predictions made using another computational program PATO. In addition, analysis is performed to investigate the effect of parameters in the model such as thermal conductivity, heat capacity, surface emissivity, reaction kinetic parameters, and pressure. The results show that surface radiation is the majority of energy consumption mechanisms, and the internal temperature distribution of materials is primarily governed by thermal conductivity and heat capacity. Moreover, pressure serves as both the independent and dependent variable of thermal response, and the heat dissipation effect of pyrolysis gas exhibits a significant increase when it exceeds 10 atm. The results can improve the understanding of the ablative thermal response process and highlight areas for optimizing the design of TPS materials.