Time-resolved Temperature Sensitive Paint Measurements on a Hypersonic Intake Ramp

Abstract

A series of experiments is performed in the High Enthalpy shock tunnel G¨ottingen (HEG) to measure the global heat-flux distribution on a hypersonic inlet ramp, consisting of a flat plate with sidewalls at an angle of attack. A newly developed TSP formulation with relatively short excitation and emission wavelengths is employed, allowing the detrimental effects of tunnel luminosity to be minimized. The paint response is sufficiently fast and image acquisition rate sufficiently high that the heat flux on the ramp surface can be determined with a temporal resolution of approximately 100 µs. An in situ calibration procedure is introduced, as the a priori calibration is found to be inaccurate with the current TSP. Two HEG conditions are investigated, one in which the main ramp flow is laminar and the other in which it is transitional. In both cases, the corner flow regions near the sidewalls are observed to transition upstream of the main ramp flow, leading to turbulent regions spreading inwards from the sidewalls. In the transitional case, substantial two-dimensional unsteadiness is observed in the transition front location; the fast-response TSP allows this motion to be resolved and compared with unsteadiness in the reservoir supply conditions. Only weak correlation is observed between the two.