Cavity Resonance Suppression Using Miniature Fluidic Oscillators

Abstract

We present a novel approach to suppressing jetcavity interaction tones using miniature fluidic devices. We first characterize miniature fluidic oscillators and then assess their effectiveness for cavity tone suppression. Further, we evaluate mass flow requirements for effective unsteady fluid mass addition. The fluidic devices used had no moving parts and could provide oscillatory flow of prescribed waveforms (sine, square, and saw-toothed) at frequencies up to 3 KHz. Our testbed for a detailed evaluation of the fluidic excitation (square wave) technique was the flow-induced resonance produced by a jet flowing over a cavity with an (length/depth) ratio of 6. In addition to schlieren photography and acoustic measurements we used photoluminescent Pressure Sensitive Paint (PSP) to map pressures on the cavity’s floor for the unperturbed and fluidically excited cases. When located at the upstream end of the cavity floor, the miniature fluidic device was successful in suppressing cavity tones by as much as ’ Senior Research Engineer, Associate Fellow AIAA ’ Principal Research Scientist, Senior Member AIAA 3 Electronics Engineer Copyright