Numerical investigation of impulsively generated high-speed jet for dynamic stall suppression

A computational study of impulsively actuated high-speed jets for dynamic stall suppression is conducted to control the aerodynamic performance of a lifting body. Jet flows are applied to the VR-12 airfoil under dynamic stall conditions. The current study demonstrates that an energetic interaction between the high-momentum jet and dynamic stall vortex is able to suppress two critical stall events, i.e., the moment and lift stalls, in the dynamic stall phenomena. The controlling mechanism of such stall events is explored using the single-jet flow under various actuation timings in a pitch period. Based on the derived mechanism of the stall control, multiple jets are utilized to suppress the severe hysteresis of the dynamic stall, because the single actuation could control only one of the stall events and not the both. Consequently, the numerical study with multiple-jet actuation reveals that the actuation of a few (3-5) jets near the lift and moment stall events could mitigate the dynamic stall as effectively as a large number (nearly 20) of jets over the entire pitch period. Furthermore, a higher actuation frequency provides an additional control benefit for dynamic stall suppression because of concentrated pulses around the two critical stall events.