Near Full-Scale Application of Suction and Pulsed Blowing to Mitigate Local Separation

In an effort to create more fuel-efficient airplanes, larger ultra-high bypass ratio (UHBR) engines are being developed. However, when installed under the wing, large-diameter engines have harmful effects on the aerodynamic performance of the wing. This is because the large and near-wing engine pylon forces a wider slat-cut-out that in turn leads to local boundary layer separation and a complex system of streamwise vortices. To regain the lift lost due to this interaction, a novel solution by implementing active flow control devices in the form of suction and oscillatory blowing devices (SaOB) is presented in this paper. Near full-scale wind tunnel tests have been conducted as part of the EU Cleansky2 INAFLOWT project with the goal of recovering the lift of this setup, using a reduced mass-flow rate, within the current airplane capability. The tests were conducted on a wing model with a chord length of 3.26 [m] at Reynolds numbers range of 4.5-8.8 millions. The approach described in this paper shows a substantial improvement in performance using significantly reduced mass-flow compared to previous successful passive and active flow control studies on the same model.