Effects of catalytic recombination on the surface of metals and quartz for the conditions of entry into the Martian atmosphere

Abstract

Heat transfer to water cooled surfaces of metals and quartz is studied experimentally in subsonic jets of dissociated carbon dioxide at a stagnation pressure of 80 hPa and enthalpy of 9 and 14 MJ/kg, corre sponding to the descent conditions of the ExoMars space vehicle into the Martian atmosphere, using an RF induction plasmatron at the Institute for Problems in Mechanics, Russian Academy of Sciences. The mea surements of heat fluxes to surfaces of different materials showed the significant effect of the catalytic prop erties of surfaces that can be arranged in the following descending order of the heat flux: silver, copper, stain less steel, quartz. The effect of strong modification of the silver surface is recorded during the tests; the max imum value of the heat flux is achieved after 15 min exposure of the surface to the jet. In the computational analysis of heat transfer, we used a two parameter model of heterogeneous recombination of O atoms and CO molecules at the surface. With this model, the effective recombination coefficient of CO molecules is deter mined on the water cooled surfaces of quartz and stainless steel, based on the experimental data on heat fluxes. 2 0. m m J J J J m m + + + = O O WO O WCO CO CO CO WCO CO 2 , , m J K c K c m J K c

Grid convergence and influence of wall temperature in the calculation of thermochemical non-equilibrium heat flux

“…Yang et al [31] researched the surface thermochemical effects on TPS-coupled aerothermodynamics in hypersonic Martian gas flow. Kolesnikov et al [32] discussed the effects of catalytic recombination on the surface of metals and quartz for the conditions of entry into the Martian atmosphere. Balat-Pichelin et al [33] performed a joint experimental and theoretical investigation on the molecular oxygen formation after atom recombination on silica surfaces.…”

Investigation of the Effect of Supersonic Flow of Dissociated Nitrogen on ZrB2–HfB2–SiC Ceramics Doped with 10 vol.% Carbon Nanotubes

“…The authors have not found a study of the interaction of ultra-high-temperature ZrB 2 +HfB 2 +SiC+C CNT ceramic with high-enthalpy flows of other gas compositions, such as nitrogen, which is the main component of the Saturn satellite Titan atmosphere (98.4%) [ 47 , 48 ], or carbon dioxide, prevailing in the Mars atmosphere [ 49 , 50 , 51 , 52 ], despite the extreme practical relevance. The authors previously studied the behaviour in supersonic jets of dissociated nitrogen of graphite samples [ 53 ] and HfB 2 –SiC and HfB 2 –SiC–C (graphene) ceramics [ 54 ], which showed that there occurred a significant change in the surface chemical nature due to ongoing reactions with atomic nitrogen and silicon removal at elevated temperatures, which causes a change in the emissivity and catalyticity.…”