Development of catalytic and ablative gas-surface interaction models for the simulation of reacting gas mixtures

We study the gas-surface interaction of dissociated air in a high enthalpy flow. A framework that provides proper gas-surface interaction boundary conditions for any flow solver has been developed in the Mutation++ library of the von Karman Institute for Fluid Dynamics (VKI). It solves the mass and energy balances at the wall taking into account catalysis and ablation. Two different catalytic models are currently available in the code: a phenomenological one called " model" and a finite-rate chemistry one. For ablation a phenomenological model for solid carbon ablators has been implemented including the three processes of oxidation, nitridation, and sublimation. The aforementioned models were used to simulate the experiments performed in the high enthalpy Plasmatron wind tunnel of VKI and the numerical results were compared to the experimental data. In the first experiment, a copper flat plate was placed in the plasma jet in order to assess its catalytic properties at off-stagnation point conditions. In the second one, the behaviour of a carbon fiber lightweight ablator was tested. The flow field was modeled by the single temperature multi-species Navier-Stokes equations in chemical non-equilibrium and solved with the finite volume code Cosmic.