Hypersonic Jet Interaction on an Axisymmetric Finned Vehicle Using Pressure Sensitive Paint

Experiments have been conducted at Mach 5.95 in a free-piston compression Ludweig tube to assess the jet interaction flow field around a scaled axisymmetric finned geometry. Fast pressure sensitive paint was employed to obtain high spatial resolution global wall pressure data over the model to elucidate the jet effects on downstream aerodynamic surfaces. Pressure transducers instrumented on the model allowed direct comparison with the PSP data, with schlieren imaging employed for complementary diagnostics. An aerodynamic shadowing effect of the in-plane downstream fin resulted from the jet wake flow and the pressure distribution on the horizontal fins was altered when compared to the jet-off case. The effect of increasing injection pressure shifted the 3-D separation front upstream and increased the magnitude of the wall pressure footprint, with the size and strength of the wraparound seen to increase in the schlieren images. A systematic shift of the PSP data was observed when compared to the pressure tap measurement which was believed to result from temperature effects and paint degradation from the hypersonic crossflow.