Microphone-Array Measurements of the Floor Pressure in a Low-Speed Cavity Flow

Abstract

The objective of this paper is to highlight the significance of spatiotemporal data and associated analysis tools in the identification of oscillation modes in cavity flows. To this end, the unsteady wall-pressure field on the floor of a shallow, rectangular cavity is experimentally investigated at a low Mach number of 0.086. The pressure measurements are conducted by using an array of 16 microphones arranged in a line along the centerline of the cavity floor, which spans its full length. Data were acquired for two cavity configurations with a length-to-depth, L/D ratio of 5 and 8. Results show that for L/D = 5, the pressure oscillations are driven by the wake mode; whereas for L/D = 8, Rossiter-type modes are observed. The ability to contrast the wake and Rossiter-type oscillations was made possible through the unique, wall-pressure, wave-number-frequency signature of each of the modes.