Suppression of flow separation of a high-lift wing with active flow control

Flow separation caused by the integration of a leading edge slat cut-out to accommodate an ultra-high bypass ratio engine reduces the maximum lift coefficient. In this study, an active flow control approach including 88 pulsed jet nozzles near the leading edge is used to control flow separation over a multi-element high-lift aerofoil. A hybrid large-eddy simulation (LES) and stress-blended eddy simulation (SBES) method is deployed to analyze flow physics and wind tunnel tests are also performed for the flow with/without control. The results show that severe flow separation is observed for the clean case by visualizing the streamlines on the airfoil's surface via numerical and experimental methods. Compared with the clean case, the stall angle is delayed by around 4°, and the maximum lift coefficient is increased by more than 15% after deploying the active flow control. Meanwhile, when the active flow control is imposed, a lift enhancement region caused by the vortex shedding downstream of the jet nozzles is formed adjacent to the leading edge, and its scale becomes larger along the spanwise direction.