ABSTRAKT

Space shuttle overheating during the re-entry phase, due to catalytic oxygen recombination on the thermal protection system, is a problem of practical and theoretical interest. The energy transfer is characterised by the product of the accommodation and the recombination coefficients. Previous measurements of recombination coefficient "gamma" on the metallic samples allowed the establishment of a catalycity scale. The purpose of this work is the modelling of the recombination of oxygen atoms and transfer of the energy to a metallic surface at stagnation point configuration by using a fluid dynamics code. The flow is described by a system of conservation (momentum, species and energy) equations. The necessary boundary conditions were provided by a model for a reactive flow-surface interaction. Under conditions similar to the experiment the field velocity, temperature and the fluxes of atomic and molecular oxygen in the reactor have been obtained. Assuming surface recombination of oxygen atoms only, the "gamma" coefficient was deduced from the ratios of atomic and molecular fluxes to the surface. The comparison of calculated values of "gamma" with the experimental ones leads to the determination of the surface recombination rate constant.