Application of Flow Control in the Slat Cut-Out Region for Lift Enhancement*

The introduction of ultra-high bypass ratio (UHBR) engines and associated increased in nacelle size necessitates a cut-out in the leading edge slat, which induces separated flow during take-off and landing resulting in a loss of lift and increased drag. Active flow control (AFC) is a promising technology with several potential applications for improving the performance of an aerodynamic body. Pulsed jet AFC has been shown capable of suppressing turbulent boundary layer separation by blowing air from the wing surface to create streamwise vortices which energise the boundary layer. AFC has been proposed as a potential solution to recover the loss in lift coefficient due to a slat cut-out. The purpose of this study – part of the Clean Sky 2 WINGPULSE project (https://cordis.europa.eu/project/id/887092), is to computationally and experimentally investigate AFC strategies in the slat cut-out region. The goal is to recover lost maximum lift coefficient. This will be demonstrated by conducting numerical (CFD) and and experimental (wind tunnel) tests. Force balance measurements to measure lift and drag coefficients, and pressure taps to measure chord-wise pressure coefficients are used in high-lift configuration of a representative wing (swept wing model with a high-speed DLR wing section and Fowler flap), which has been used in prior AFC studies on slat cut-outs. To-date, 3D numerical simulations and force balance tests have been conducted for the no flow control case and baseline flow control case. Further flow control cases will be explored, aimed at maintaining the aerodynamic benefit of AFC while reducing the net mass flow and hence energy input.