Hypersonic boundary-layer separation detection with pressure-sensitive paint for a cone at high angle of attack

A measurement technique for identifying lee-side crossflow-induced boundary-layer separation on a blunt \(7^{\circ }\) half-angle circular cone at high angle of attack has been developed and tested. Previous work has shown that local minima in root-mean-squared (rms) pressure fluctuations on the surface are good identifiers of separation. These surface pressure fluctuations are measured with a temperature-corrected, high-frequency-response anodized-aluminum pressure-sensitive paint (AA-PSP). This AA-PSP was made in-house to provide the high frequency response required for this work. The sensor’s frequency response of 3 kHz proved to be fast enough to detect lines of local minimum rms pressure fluctuations indicative of separation on the lee side of the cone for angles of attack from \(9.8^{\circ }\) to \(15.8^{\circ }\). A shift in the separation location towards the windward side of the model was observed as angle of attack increased; however, the separation location converged to a constant azimuth for angles of attack greater than or equal to \(1.8\times\) the cone’s half angle.