Stall characteristics of high-lift device improved by slotting on leading-edge slat

High-lift devices are widely used on multi-element wings of large civil aircrafts. At large angles of attack, flow separation may occur over upper surfaces of leading-edge slats of multi-element airfoils. The flow separation would increase the thickness of the induced wake flow rapidly and enhance the interaction between the wake and the downstream boundary. This will reduce the circulation and lift and finally result in the stall. This paper puts forward a method to improve the aerodynamic performance of high-lift devices by slotting on leading-edge slats. Flow fields and parametric effect of the slotting are investigated based on numerical simulations by solving Reynolds-Averaged Navier-Stokes equations. Results show that the slots on leading-edge slats can effectively delay the flow separation by inhibiting the development of the wake flow and its interaction with downstream boundary layers. The adverse impact induced by the stall can be alleviated significantly as a result. However, the control effect is closely related to the slot position and the direction of the exiting jet. Therefore, to obtain a favorable improvement of aerodynamic performance, the slot should be reasonably designed according to the shape of the leading-edge slat and also to the surrounding flow field.