Numerical Study of the Thermal Response of High-Temperature Ablative Materials

Abstract

A theoretical model accounting for the effects of thermal nonequilibrium, temperature-dependent material properties,pyrolysis reaction, and thermochemical expansion is tkveloped to predict the thermal response of high-temperature ablative materials when expased to hyperthermal environments. The model, which is developed by using the volume-averaging and the finite volume techniques, is npplied to predict the thermal response and the underlying heat transfer mechanisms of two typical ablative materials having distinctly different properties. From the numerical results, iI is found that the method of mixture enthalpy leads to a better prediction of the thermal response than the method of mixture specific heat. It is also found that for an ablative material wilh relatively large permeability and porosily, the cooling effect of transpiration gases is significantly overpredicted by using the assumption of local thermal equilibrium.

Silicone polymer composites for thermal protection system: fiber reinforcements and microstructures

“…Shih, Cheung, Koo, and Yang [13][14][15] developed a physical model to describe the transient ablation phenomenon of high-temperature ablative materials for with and without the formation of a melt layer on the material surface. The model has been applied to H41N (larger heat of ablation) and to MXBE-350 (smaller heat of ablation).…”