Transpiration-Cooled Hypersonic Flight Experiment: Setup, Flight Measurement, and Reconstruction

The present paper presents the in-flight measurement of the transpiration cooling experiment Aktive Kuhlung durch Transpiration im Versuch (often referred to as AKTiV) flown on the suborbital reentry configuration Sharp Edge Flight Experiment II (often referred to as SHEFEX II). Thermal response of the structure is measured just up- and downstream of a cooled sample with a noncooled reference setup on the opposite side of the vehicle. The measurement shows that the heat flux is reduced upon coolant exhaust. The maximum temperature reduction with 87K is observed on the porous sample, while downstream the sample, the temperature is reduced by 75K by film cooling. This corresponds to cooling efficiencies of 58 and 42% on the sample and downstream, respectively. The evaluation is supported by the semi-analytical tool HEATS, based on a transient heat balance at the surface. Comparison of the results with HEATS shows that the heat flux predicted with HEATS is in good concurrence with the measured temperatures on the cooled sample, as well as upstream and downstream with a maximum deviation by 14%. The analysis suggests that the flow condition around the sharp-edged, faceted vehicle remained laminar longer than expected.