Effects of Pyrolysis Reaction and Gas Characteristics on the Thermal Response of Resin-Based Ablative Materials

Investigation of the ablative thermal response process is crucial for the development of thermal protection systems for re-entry vehicles, but the research of the pyrolysis impacts on this response of resin-based ablative materials still remains inadequate. In this paper, we develop a high-accuracy numerical model of the ablative thermal response, which is solved by an innovative finite difference method and implemented using a Python procedure. The heat capacity of the material in the model is calculated by a quantum correction based on molecular dynamics. After verifying the model with the well-validated code PATO, the effects of pyrolysis are investigated from two perspectives: pyrolysis reaction and pyrolysis gas. The results show that the slow pyrolysis reaction resulting from the high activation energy weakens the overall heat dissipation effect of the material, but the specific influence of the activation energy on the internal temperature should be evaluated together with the pyrolysis enthalpy. In addition, changes in the reaction parameters have a significant effect on the ablative thermal response via the resulting mass flow rate of the pyrolysis gas. The heat flux supplied is effectively reduced by the effects of increased thermal blocking and wall enthalpy by the pyrolysis gas, and about 30% of the net heat is dissipated internally by the pyrolysis gas.