Experimental Determination of Recombination Coefficients at High Pressures

Abstract

In the arc-heated facility L2K, an experimental campaign was performed which aimed at the determination of recombination coefficients at conditions with high stagnation pressure which are of particular interest for re-entry from LEO. Tests were performed on two TPS materials with a variation of surface temperature, stagnation pressure, and atmosphere. During a preparatory campaign suitable operating conditions and facility configurations were determined for all 24 test cases. Based on the measured data, details of the flow conditions could be identified. These data were used to evaluated recombination coefficients according to Goulard’s method. Due to the low dissociation rates at the higher stagnation pressures, the evaluation was successful for the lowest stagnation pressure level of 2000 Pa mainly. In nitrogen flow, results were obtained for the high temperature cases only.