Control of Flow-Acoustic Resonance Using Sweeping Jets

This study proposes a sweeping jet as a novel solution to control catastrophic flow-acoustic resonance through a combined experimental andscale-adaptive simulation (SAS) strategy. The relationships between resonance intensity and the geometry of the dual sweeping-jet controllers (SJCs) and mass ratio of the jet flow to mainstream flow were established by the wall-pressure measurements. The system with dual SJCs at two upstream channel-branch intersections with spanwise jet sweeping achieved the best control performance at the low mass ratio of Qr = 1%. Through complementary simulations, self-sustained unsteady flow dynamics within dual SJCs, strong flow-acoustic resonance within the channel-branch system and complete suppression of the aeroacoustic field by themost efficient dual SJCs were demonstrated. The simulation results were first validated in terms of the frequency and amplitude information of the experimentally measured wall-pressure fluctuations. Subsequently, a proper orthogonal decomposition analysis was conducted and a large-scale synchronous sweeping behavior was observed when the jet flow proceeded from the fluidic oscillators to the free space. Thereafter, SAS results revealed the dual SJCs could remarkably attenuate velocity fluctuations, shear-layer momentum thickness, and Reynolds and Lighthill stresses. These improvements were achieved by completely suppressing the large-scale shear-layer vortex shedding into a series of horseshoe vortices.