Heterogenous Gas-Wall-Interactions in high enthalpy Non-Equilibrium Flows

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The planned project proposes the calibration of complex catalytic models for high-temperature materials in atmospheric entry relevant conditions in order to better understand gas-specific and single reaction mechanisms and their dominances at wide range of temperatures and pressures. The work proposal includes the implementation of an advanced methodology to experimentally determine recombination coefficients in high-enthalpy and non-equilibrium flows generated in plasma wind tunnels. Moreover, it includes experimental verifications for numerically reconstructed gas parameters and a validation of the methodology. Inductively heated plasma generators (IPG3-5) are I use for the IRS high-enthalpy plasma wind tunnel facility PWK3, which will be employed for the experimental part of the investigation in combination with adequately selected plasma diagnostics. An emphasis is put on the characterization of the boundary layer in order to increase the level of confidence for the assessment of the gas-surface interactions and of its relevant properties. An emissivity-independent technique for the determination of the radiative heat flux and the wall temperature is proposed in order to reduce the experimental uncertainties. For the numerical reconstruction of the boundary layer, supporting and complementing the experimentally obtained gas transport parameters, the IRS Upwind Relaxation Algorithm for Non-equilibrium flows of the University of Stuttgart (URANUS) will be used. Here, the extraordinary constellation is to be seen in the fact that complementary experimental numerical investigations of complex gas flows can be performed at one and the same institution. Moreover, the verification and validation level of URANUS is adequately well developed due to the successful comparison of simulation results with both in-flight data and experimental data from plasma wind tunnels.Samples out of silicon carbide SiC, and grade 5 titanium Ti6Al4V are in the course of this project, for which the gas-surface interaction properties are of high interest in space and earth applications.The project is planned for a three-year duration and is divided in five work packages, which logically and chronologically structure both the experimental and numerical activities. A small but essential upgrade of the existing plasma diagnostics is required in order to accomplish a proper flow calibration and material characterisation. Eventually, the flight-experiment catalysis-based sensor PHLUX will be assembled and exposed to a well-known and independently characterised flow condition in PWK3 for the validation of the methodology. The plasma composition will thus be assessed and respectively compared with results from other independent measurement techniques.