Incorporating active flow control in future wing designs for ultra-high bypass ratio engine integration.

The introduction of ultra-high bypass ratio engines creates a significant challenge to wing-designers. The increased nacelle size necessitates a cut-out in leading-edge slats, this induces separated flow at take-off and landing resulting in a loss of lift and increased drag. Active flow control (AFC) is a proven technique to suppress turbulent boundary layer separation and the use of pulsed jet actuators (PJA) is of interest thanks to the lower energy requirements when compared to steady blown or suction techniques. However, very little work has been done to prove this technology is viable for commercial use. The purpose of this study was to experimentally compare different AFC strategies such as momentum redistribution and momentum injection through variations in PJA layouts. The goal was to recover lost CL_max due to the slat cut-out (~6%), the optimum configuration of PJA was found by comparing the required energy input. This was demonstrated by conducting large scale wind tunnel tests, using oil flow technique to visualize surface skin friction lines and force balance measurements at representative Reynolds numbers for take-off conditions on a representative future-wing design.