Heterogeneous Recombination of Nitrogen Oxide in Problems of a High-Speed Flow of Dissociated Air around Blunt Bodies: Influence on the Chemical Composition of the Gas and Heat Exchange with the Surface

Abstract

An important component of space flight safety is the effectiveness of thermal protection of the surface of reusable spacecraft, which is ensured by the use of modern materials with the lowest catalytic activity when interacting with the atmospheric gas mixture. Based on a stage-by-stage heterogeneous kinetics of the interaction between a dissociated gas mixture and the surface of β-cristobalite, a numerical simulation of the supersonic multicomponent nonequilibrium-dissociated air flowing around a cylindrical model is performed in the framework of Navier–Stokes equations taking into account the chemical reactions in the flow under the conditions of heat exchange experiments on with the use of a VGU-4 induction RF plasmatron (developed at the Institute for Problems in Mechanics of the Russian Academy of Sciences (IPMech RAS)). A comparative analysis of the calculations of the flow in the plasmatron with and without taking into account nitrogen oxide formation on the streamlined surface has been performed to show that it is required for taking into account the heterogeneous recombination of nitrogen oxide in boundary conditions. The dependence of flow characteristics on the density of adsorption sites is established over a broad range, representing regimes from non-catalytic to full catalytic behavior. The contribution made by diffusion and thermal conductivity processes to the heat flux towards the surface is demonstrated for different modes of gas interaction with the surface material.