A computational approach to heat transfer and ablation in space capsule insulation

Abstract

In this article, the heat transfers and ablation phenomena of thermal insulations utilized in manned space capsules are investigated. In this regard, by collecting and solving the equations related to ablation insulations, a computer program has been developed that is able to predict the thermal response of these insulations under various operating conditions. This approach considers mass and heat transfer equations in two-dimensional solid bodies. To solve these equations, finite volume method and implicit formulation for time dependence have been used. The reaction equation, written in the form of Arrhenius, is solved using the Runge-Kutta method, and the density and the flux of the gas produced at each step are obtained. Furthermore, a practical model with low computational requirements and execution time and execution time is presented to consider the regression rate based on determining the identifier for destroyed cells, charred cells, and virgin material. The research results demonstrate that increasing the thickness of the layers, the heat of decomposition and ablation, the intensity of the reaction, and reducing the thermal diffusion coefficient, density of char, and temperature of ablation enhance the efficiency of thermal insulation. Validation of the model with experimental results in silica-phenolic insulation reveals a good agreement between simulation and experimental observations. Additionally, it was shown that for a carbon-phenolic insulation with a thickness of 5 mm in the specified space capsule under the given conditions, the maximum recession rate is 1.9 mm at a maximum temperature of 1000 K and 4.9 mm at a maximum temperature of 1300 K.