Effect of shear-layer control on leading-edge vortices

The effect of shear-layer control on leading-edge vortices over delta wings with sharp leading edges was investigated. By using suction near the separation point, the direction of the shear layer, and the location of the main vortex as well as its structure could be modified. The maximum swirl angle in the core and overall circulation decreased with suction. This caused the vortex breakdown location to move downstream. When the suction slot was located slightly inboard, the swirl angle was found to increase, causing the breakdown location to move upstream. It is shown that extremely small amounts of leading-edge suction can modify the location of the vortex core and can thus be used to induce rolling moment.