Influence factors on the multi-field coupling performances of charring ablators on the basis of a mesoscopic ablation model

The prediction of the multi-field (thermal-fluid-chemical-mechanical) coupling performances of charring ablators used in integral thermal protection system (ITPS) for reentry vehicles is subject to the aerothermodynamic environment. A mesoscopic ablation model is built in this manuscript, which takes the mass, momentum, energy conservations and the mesoscopic mechanics model for the solid and the gaseous phases produced from the ablation process into consideration. Based on this model, firstly, the thermal responses and the effective modulus for existing materials are calculated. The simulation results are compared with the experimental data to validate our developed mesoscopic ablation model. Then, the heat and mass transfer of each phase in the ablator, the fluid performance of the pyrolysis gases, the chemical responses of the pyrolysis reactions, as well as the effective mechanical properties under ultra-temperature for charring ablators with different influence factors (the gasification coefficient and the fiber's volume fraction) are simulated and analyzed. The numerical results indicate that the variation of the fiber's volume fraction has significant influence on the coupled ablative performance. The effective elastic modulus of the ablator can be predicted by a temperature dependent linear function. The pyrolysis reactions proceed completely with producing large amounts of pyrolysis gases in the ablator with a low effective elastic modulus.