AIAA-98-0776 Planar Laser Imaging of High-Speed Cavity Flow Dynamics

Simultaneous Planar Laser Scattering (PLS) imaging and fluctuating pressure measurements have been made for a rectangular cavity in a Mach 5 turbulent boundary layer. Preliminary results are presented in the form of instantaneous side view images, and power spectra for cavity length-to-depth ratios of 3, 4, 6, 7, and 8. High-frequency response pressure transducers were installed in the rear and front walls of the cavity to monitor the shear layer impingement at the top of the rear wall, and to determine the upstream propagation time of acoustic waves from space-time-correlations. Instantaneous side view PLS images show the impingement shock and expansion waves, whereas the large turbulent structures at the outer edge of the shear layer mask the deflection of the shear layer into the cavity, even for the largest cavity tested. Preliminary analysis of the fluctuating pressure data suggests that the shock frequencies and the duration of the impingement shock are not sensitive to cavity length-to-depth ratio.