NUMERICAL STUDY OF THE THERMAL RESPONSE OF HIGH-TEMPERATURE ABLATIVE MATERIALS

A theoretical model accounting for the effects of thermal nonequilibri um, temperature-dependent material properties, pyrolysis reaction, and thermochemical expansion is developed to predict the thermal response of high-temperature ablative materials when exposed to hyperthermal e nvironments. The model, which is developed by using the volume-averagi ng and the finite volume techniques, is applied to predict the thermal response and the underlying heat transfer mechanisms of two typical a blative materials having distinctly different properties. From the num erical results, it is found that the method of mixture enthalpy leads to a better prediction of the thermal response than the method of mixt ure specific heat. It is also found that for an ablative material with relatively large permeability and porosity, the cooling effect of tra nspiration gases is significantly overpredicted by using the assumptio n of local thermal equilibrium.