Numerical study of transient thermal ablation of high-temperature insulation materials

A physical model has been developed to describe the transient ablation phenomena of high-temperature insulation materials for the cases with and without the formation of a melt layer on the material surface. The model takes account of the effects of transient melt-layer formation, variable ablation temperatures, and heat of ablation of the material. Validity of the model has been demonstrated numerically by comparison with available analytical solutions for the special case of a constant ablation temperature. For the general case of variable ablation temperatures, appreciable differences in the predicted ablation rates have been found between the cases with and without melt-layer formation for materials having low heats of ablation and for large imposed external heat fluxes. The present study clearly indicates that the melt-layer effect cannot be neglected at high external heat fluxes, especially for materials such as MXBE-350 that have low heats of ablation.