Investigation of Cavity Flow Using Fast-Response Pressure-Sensitive Paint

An experimental study was conducted to investigate the pressure fluctuations on the entire sidewall of a rectangular cavity with an L/D of 5.67 using fast-response pressure-sensitive paint. Additionally, the performance of four different passive flow-control devices was quantified. Experiments were conducted in the Trisonic Gasdynamics Facility at the Air Force Research Laboratory at Mach 0.7 and 1.5. The frequency spectrum (including Rossiter tones) and sound pressure levels obtained from the pressure-sensitive paint measurements are validated against data taken with conventional dynamic pressure sensors. The complex flow phenomena over the cavity wall were visualized, and full-wall pressure spectra were calculated. The rod in crossflow showed the best peak suppression, followed closely by the flat spoiler. The large triangular steps showed moderate peak suppression, whereas the ridges did not suppress the peaks at all. High-resolution measurements of both temporal and spatial pressure fluctuations on the wall allowed for the visualization of sound pressure level distribution over the entire cavity wall. This revealed a strong dependence between the Rossiter tone modes and the spatial distribution of sound pressure levels that was not possible to resolve with traditional discrete pressure transducers.