Investigation of Low Enthalpy Surface Chemistry Anomalous Behavior in Ablative Modeling

Numerical simulations of planetary entry rely critically on surface chemistry data generated from thermochemical equilibrium programs that predict the chemical and physical properties of the thermal protection systems' (TPS) material. Recently, anomalous behavior in the convective flux term beyond peak heating has resulted in a second peak during the low enthalpy cooling phase of entry. This phenomena is now being called the Endgame Recession, since it produces a spike in surface recession nearly equivalent to the peak heating in some cases. To increase the accuracy and trustworthiness of numerical predictions, thereby guaranteeing fidelity with respect to a single converged solution, this phenomena needs to be investigated. A systematic intercode comparison is planned to test various ablative materials and their corresponding datatables to identify the root cause of this phenomena.