Material catalysis in high enthalpy air flows

Abstract

The qualification of thermal protection systems (TPS) and numerical design tools for re-entry vehicles and space probes requires the ability to understand and to duplicate the prevailing complex physicochemical phenomena, including thermal and chemical nonequilibrium near the surface of a body which enters the atmosphere of the Earth or other celestial bodies. At the Institutfiir Raumfahrtsysteme of the University of Stuttgart four plasma wind tunnels PWK1-4 are in operation to simulate the thermal, aerodynamic and chemical loads on the surface of a space vehicle. In order to investigate the catalytic behaviour of different materials under thermal and chemical loads, measurements with stationary and instationary heat flux probes, equipped with different sensor materials were carried out and partially compared with mass spectrometer measurements with different orifice materials. Results of the heat flux probe and mass spectrometer measurements as well as results of numerical simulations of the mass spectrometer orifice flow are presented and discussed in this paper. It is shown that in air increasing surface temperature leads to increased formation of nitride oxide.