Active flow control in high-speed internal flows
Gissen, Abraham Naroll
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Manipulation of high-speed duct flow by streamwise vorticity concentration that are engendered by interactions of surface-mounted passive and active flow control actuators with the cross flow is investigated experimentally in a small-scale wind tunnel. The controlled formation of these streamwise vortices can be a key element in the mitigation of the adverse flow effects in a number of applications including aero-optical aberrations owing to unsteady local transonic shocks, pressure recovery and distortion due to secondary flows in embedded propulsion system, thrusts reversal and augmentation for aerodynamic control. The effects of the actuation are investigated using various converging-diverging inserts along one of the test section walls. Passive actuation includes micro-vanes and active actuation is effected using high-frequency, surface-mounted fluidic oscillators. Hybrid actuation is demonstrated by combining the passive and active actuation approaches to yield a “fail-safe” device with significant degree of controllability. The investigations consider the effects of the surface actuation in three application areas namely, stabilization of transonic shocks, suppression of total-pressure distortion in offset ducts, and mitigation of separation in internal flow turning.