Passive and active leading edge devices on a simple swept back wing

Tests were carried out on a 45° swept back wing having several Aspect Ratios ( AR), but most of the presented results are concerned with a highly unstable, high AR wing. Test velocities ranged between 20-50m/s, depending on specific test needs (e.g. Pressure Sensitive Paint, PSP, required higher speed). The wing being based on a NACA0012 airfoil had a round leading edge that prevented the generation of a leading edge vortex prior to tip trailing edge stall, unless a protuberance like a vortilon or a snag were placed at the leading edge. The shape of the leading edge was modified in order to assess its significance. Interaction between the leading edge vortex and the trailing edge separated region resulted in non-linear pitch behavior that was controlled by passive and active means. At larger incidence angles the leading edge vortex propagated inboard and the trailing edge separated region moved upstream requiring a change in the control strategy in order to remain effective. Balance results, flow visualization and Pressure Sensitive Paint show how to force the downstream turn of the leading edge vortex in order to control its path and its effect on pitch-up.