Thermal Ablation Simulations of Quartz Materials

A thermal ablation model for glassy materials is proposed. The model includes mass losses from evaporation and condensation as well as from the moving molten layer driven by surface shear force and pressure gradient. This ablation model can be applied in simulations of meteoroid or glassy thermal protection systems for spacecraft. Time-dependent axisymmetric computations are performed by coupling the fluid dynamics code, Data-Parallel Line Relaxation program, with the material thermal response and ablation code, Two-Dimensional Implicit Thermal Ablation simulation program, to predict surface mass lost rate and shape change. For model validation, surface recession and shape change of a quartz sphere-cone arc-jet model are computed, and the predictions are consistent with arc-jet data obtained at NASA Ames Research Center. Parametric studies are also performed to understand the effect of uncertainties of surface heat flux, surface emissivity, and viscosity of molten layer on the recession prediction.