Pyrolysis layer model of polymer matrix composites with heating rate and pressure

Heating rate and ambient pressure affect the resin matrix pyrolysis process, the pyrolysis gases flow state and the temperature distribution of polymer matrix composites as heatshield of spacecraft. Therefore, a pyrolysis layer model with heating rate and pressure is presented. Accuracy of prediction of heating rate distribution calculated by the presented model is validated by comparing Arcjet wind tunnel test results of phenolic impregnated carbon ablator (PICA). After that, the thermal behavior of PICA under different heating rates is predicted by this presented model. It is indicated that the mass injection rate of pyrolysis gases increases, the bondline temperature declines and the char layer's density decreases as the heating rate rises. Besides, from material bondline to material surface, the heating rate maximum increases exponentially along material thickness. This study contributes to the optimal design of the thermal protection system of spacecraft.