Numerical Study of High Performance Ablative Thermal Protect System by Adding Phase Change Material

Under extreme thermal environment, ablation process of thermal protection system is a key issue in atmospheric re-entry and hypersonic flight vehicles; it displays a strong coupling between ablation mass, velocity and heat transfer. This article presents a method for combining the ablating and melting process, building a right triangle carbon-carbon model for ablation mixed with octadecane phase change material to absorb the heat of combustion delaying the movement of burning interface. For the moving of boundary, it is treated by the modified Stefan model coupled with chemical reaction and thermal radiation at the front leading boundary. The governing equation of heat transfer considering the melting process of phase change material is given by referring the enthalpy method. The effect of volume ratio and aerodynamic heating on the ablation interface and net heat flux on the interface are investigated. Result shows that high volume ratio of the phase change material delays the movement of the interface, and decreases the net heat flux of the interface; on the other hand, high aerodynamic heat accelerates the movement of the interface and increases the interface net heat flux at a given time point. This study can give a rule on how the volume ratio of phase change material influence the ablative process quantitatively.