Global measurements of hypersonic shock-wave/boundary-layer interactions with pressure-sensitive paint

Abstract

Global surface pressure measurements have been carried out on a 7° half-angle circular cone/flare model at nominally zero angle of attack using pressure-sensitive paint (PSP). These experiments were conducted to illustrate the PSP technique’s usefulness and effectiveness at measuring the unsteady structures inherent to hypersonic shock-wave/boundary-layer interactions (SWBLI) on a global scale. Mean and fluctuating surface pressure was measured with a temperature-corrected, high-frequency-response ( $$\approx 10$$ kHz) anodized-aluminum pressure-sensitive paint (AA-PSP). This AA-PSP was made in-house to provide the high frequency response required. Methodologies for tracking the boundary-layer separation and reattachment shock feet in both time-averaged and instantaneous senses are provided and discussed. Excellent agreement is observed between the different metrics. In addition, spectral analyses were conducted on a global scale providing insights into the unsteady dynamics of the shock feet and structures under the separated shear layer. These spectral analyses identified a smooth, low-frequency bandwidth centered at $$\approx 500$$ Hz, which is characteristic of the shock-foot oscillations. These experimental findings validate the usefulness of AA-PSP to provide global physical insights of unsteady SWBLI surface behavior in the hypersonic flow regime. Similar methodologies can be incorporated in future experiments to investigate complex and novel SWBLI.