MODELLING OF THE HEAT TRANSFER OF ATOMIC OXYGEN RECOMBINATION ON CERAMICS AND SEMICONDUCTORS TARGETS

摘要

The goal of this work is to study the heat and mass transfer phenomena at the solid/gas interface for thermal protection system of space vehicles. Catalycity qualified the heat flux due to the oxygen atoms recombination (gamma coefficient) and their energy accommodation (beta coefficient) on the surface of the material. So, we propose an approach to modelling and to simulate the recombination of oxygen atoms and the energy transfer to a metallic surface at stagnation point configuration by using a computational fluid dynamics code. The flow is described by a system of conservation (momentum, mass and energy) equations. The necessary boundary conditions were provided by a model for a reactive flow-surface interaction. We have obtained the field velocity, temperature and the fluxes of atomic and molecular oxygen in the reactor under similar conditions to experiments. Assuming surface recombination of oxygen atoms only, the "gamma" coefficient was calculated from the ratios of atomic and molecular fluxes to the surface. The simulation was made on ceramics and semiconductors materials. The comparison between calculated values of "gamma" and experimental ones leads to the determination of the surface recombination rate constants.