Material Response Modeling of Melt Flow-Vapor Ablation for Iron

The ability to accurately predict melt-dominated ablation of meteoritic materials is important for risk assessment of near-Earth asteroids and survivability of reentering space debris. Despite previous computational studies that involve melt ablation for glassy materials, the application of incompressible gas boundary-layer theory to melt/vapor formation has largely been applied to limited surface heating rates and vapor-dominated regimes. A melt ablation formulation near stagnation regions, for crystalline and glassy materials, is implemented here and validated with ground experiments performed for iron under hypersonic flow conditions. The mathematical model does not neglect temperature gradients in the molten layer or assume domination of either melt or vapor formation. The implementation of this comprehensive melt/vapor ablation numerical model helps provide domain-independent engineering recession estimates. By using computational fluid dynamic-driven surface properties and radial basis function interpolation-driven dynamic meshes to predict stagnation-point melt ablation, it is shown that melt initiation is predicted within 10% of pyrometer data and that simulated recession is dominated by melt flow contributions at the extreme operating limits of a hypersonic arc-jet test facility. The melt thickness shows a strong parabolic dependence on heat transfer coefficient variation. Shape change validation results of test articles accounting for this variation are discussed.