Investigating Near-Wall Structures in Swept SBLI with Fast-Response PSP

The global dynamic properties of swept Shock/Boundary-Layer Interactions (SBLI) have been historically difficult to study due to the highly three-dimensional flow topology and limitations of acquiring instantaneous pressure fluctuations using pointwise measurements with traditional sensors. A flowfield generated by the interaction of a Mach 2 turbulent boundary layer and an oblique shock induced by a sharp fin is investigated using polymer/ceramic Pressure-Sensitive Paint (PSP), where PSP is applied on the floor as well as the fin surface. This non-intrusive technique permits high-spatial-resolution pressure fields of the entire flowfield to be captured and is validated with in-situ unsteady pressure transducers at key locations in the interaction. These initial results show the presence of spatially coherent structures underneath the interaction that are strongly correlated with localized pressure fluctuations simultaneously recorded on the fin surface.