Remote Control of Stalled Flow by Vortex Rings

Abstract

Flow separation from a flat plate airfoil is controlleed by impinging vortex rings. The vortex rings were generated at a position apart from the airfoil to act as a carrier of energy to suppress the separation Momentum defects in the wake of the airfoil were obtained as functions of the circulation and the frequency of introduction of the vortex ring to demonstrate that the separation zone is actually reduced. The mechanism of suppression of separation is clarified by the phase-averaged flow visualization and velocity distributions.