Optimized design and aerodynamic characteristics analysis of combined airfoil with leading-edge concave and convex structure

To further explore continuously the methods of airfoil modification and to improve the airfoil aerodynamic performance, the combined airfoil by profile modification design of the traditional airfoil and the biological airfoil was designed and the aerodynamic characteristics of the combined airfoil through numerical simulation was analyzed. At the same time, the design of the leading-edge concave and convex structure of the combined airfoil was optimized, and the parameters with the best aerodynamic performance were optimized by orthogonal test, and the aerodynamic characteristics of the optimal leading-edge combined airfoil were analyzed. The result shows that the combined airfoil has a higher lift coefficient at small angles of attack compared to the standard NACA64-618 airfoil, with a maximum lift coefficient increase of 7.3% and a maximum lift-to-drag ratio increase of 9.98% for the leading-edge combined airfoil with leading-edge concave and convex structure. The forward shift of the curvature of the combined airfoil expands the area of the negative peak pressure on the suction surface and increases the pressure difference between the upper and lower surfaces of the airfoil, thus improving the aerodynamic performance. The leading-edge combined airfoil forms a pair of reverse vortices on the suction surface of the airfoil near the trailing edge due to the existence of the concave-convex structure of the leading-edge concave and convex structure, which increases the area covered by the fluid on the airfoil surface and inhibits the early occurrence of flow separation, thus achieving the effectiveness of stall delay.