Duty-Cycle-Dependent Vortex Dynamics in Pulsed Jet Flow Control on Swept Wings

Active flow control of high-lift multielement swept wings remains a critical yet underexplored field in aerodynamics. This study investigates the effects of the duty cycle (DC) and the jet-to-freestream velocity ratio (VR) on pulsed jet flow control (PJFC) actuators near the leading edge of a multielement swept wing with three major innovations. First, a threshold effect is identified at [Formula: see text]. Below this threshold, a low DC actuation achieves comparable or superior maximum lift enhancement relative to a high DC operation. Second, mechanistic analysis reveals that at a high DC, the initial jet-induced vortex fails to merge with the dominant shear-layer vortex, leading to the emergence of an additional high-frequency shedding mode. In contrast, a low DC actuation increases the maximum lift coefficient by expanding the favorable suction pressure region, particularly at a lower VR. Third, PJFC delays the stall angle by approximately 4–6 degrees and achieves significant drag reduction at moderate angles of attack. These findings provide novel insights into the underlying mechanisms and enable a physics-informed selection of the VR and DC in effective active flow control on swept high-lift wings.