Numerical and experimental analysis of capsules ablation and shape change including heating transient effects

Designing thermal protection systems (TPS) for ballistic re-entry capsules requires both reliable numerical tools and experimental facilities in order to evaluate surface ablation and its shape change. Low-temperature ablators can be experimentally employed in low-enthalpy wind tunnels to overcome limitations of classical hypersonic experimental facilities, which can not induce the real TPS capsule shape change, due to limits in inflow total enthalpy, velocity, or experimental test time duration. Hence, in order to prove low-temperature ablators shape change relevance, a correspondence must be established between the in-flight and on-ground ablative and aerodynamic behavior of a re-entry capsule. The main objectives of this work is to perform numerical simulations in order to check the flight relevance of the ground tests. Simulations including an ablative boundary condition have been performed for both wind tunnel conditions and re-entry flight conditions. This allowed to study the relation between the shape change obtained with the low-temperature ablator in the wind tunnel conditions and the real carbon-based ablator in flight.