Application of Ultra-Fast Internal Temperature Sensitive Paints to a Hydrogen Combustion Flow

The precise determination of the surface heat flux is mandatory for experiments in high enthalpy impulse facilities. The usage of surface-mounted temperature sensors like thermocouples or thin film gauges is common in these facilities. The High Enthalpy Shock Tunnel G¨ottingen, HEG, is one of the major European hypersonic test facilities of this kind. Thermocouples and thin film gauges guarantee fast response times in the order of a few microseconds and therefore a high temporal resolution. But the spatial resolution is quite limited due to the sensor size and it’s challenging to attach sensors on complex or sharp-edged models. A non-intrusive option is the use of the technique of temperature sensitive paints (TSPs). The application of TSP enables the measurement of spatially resolved surface temperatures which allow the subsequent calculation of surface heat fluxes. TSP has been successfully applied in HEG [fast_tsp] to external flows. The application of the technique to an internal flow will be presented in this paper. The measurement technique will be used to study hydrogen combustion processes within the propulsion unit of a small scale flight experiment wind tunnel model of the LAPCAT MR2 vehicle.