Microjet Flow Control Effectiveness of Cavity Configurations at Low Speeds

Abstract

An experimental study was conducted to investigate the aeroacoustics of open-and closed-cavity configurations with and without flow control using microjets at low speeds. The cavity models had length-to-depth ratios of 2, 10, and 18, representing open, transitional, and closed cavities, respectively. The investigation was carried out at a flow speed of 16 meters per second. The microjet effectiveness was tested for jet velocities of 8, 16 and 24 meters per second. The vortex shedding aft of the trailing edge was reduced when the microjet velocity was equal to that of the freestream (16 meters per second). The results from the transitional cavity experiment, with a length-to-depth ratio of 10, showed that either higher microjet velocities or different locations of the microjets may be required to have any significant effect on the cavity flow characteristics. Nomenclature= voltage X c = measured distance from cavity leading edge X j = measured distance from center of jet δ = boundary-layer thickness (immediately upstream of the cavity opening) δ = boundary-layer displacement thickness (immediately upstream of the cavity opening) θ = boundary-layer momentum thickness (immediately upstream of the cavity opening) ρ ∞ = density