Curved leading edges and wing tips help enhance the lift on insect wings

Shape of an insect wing is important in determining the aerodynamics during its flapping motion. Most studies on the insect-wing aerodynamics simplify the wing shapes with a straight leading edge. Previous studies show that a stable leading-edge vortex (LEV) is responsible for the higher lift observed in insect wings. However, a straight leading edge and a sharp wing tip might disturb the spanwise transport of the excess vorticity required to keep the LEV size intact. In the present work, rotating wings of various leading edge curvatures are numerically simulated at insect Reynolds numbers to observe the effect on the leading edge vortex and the lift. The study reveals that the curved leading edges and wing tips enhance the lift acting on the wing as a result of the increased vorticity flux from the leading-edge vortex to the tip vortex.