Ablation model based on porous charring layer under alumina erosion condition

Abstract

The porous medium with a carbide layer and the mechanical denudation accompanied by the reaction process make the study of an ablation model more complex. The chemical vapor deposition and thermal chemical ablation processes of pyrolysis gas and fuel gas in the porous structure of a carbonized layer and the erosion process of a fuel gas and particles on a carbonized layer were studied. A thermal–mechanical coupled ablation model of ethylene propylene diene monomer (EPDM) based on the complex physicochemical process of the porous structure of a carbonized layer was established. An Arrhenius formula was used to calculate the carbon deposition and consumption caused by thermochemical reactions and the porosity evolution in the carbon layer. Based on the theory of elastic–plastic indentation fracture, a particle erosion model of the carbon layer was established. The coupling of particle erosion and chemical erosion was completed and applied to the EPDM insulation prediction. The numerical calculation of an EPDM insulation material showed that the maximum error between the experimental results and the numerical results is less than 12%, and the accuracy of the particle erosion model is acceptable. Therefore, the model proposed can be used to predict the erosion rate of an EPDM in a solid rocket motor.