Experimental evaluation of sinusoidal leading edges

Experimental evaluation of the sinusoidal leading-edge (LE) planforms on an NACA 63-021 airfoil section are discussed. The larger amplitude sinusoids created 'softer' stall characteristics by maintaining attached flow at the peaks despite separated flow in the troughs. The addition of LE tubercles to a three dimensional (3D) idealized flipper increased the maximum lift coefficient while reducing the drag coefficient over a portion of the operational envelope. The effects of extending the stall point for lifting surfaces at similar Reynolds numbers is considered to have application to small-unmanned aerial vehicle (UAV). The substantial loss in lift and increase in drag means that the scallops had largely a 3-D benefit that is a function of the planform shape and the Reynolds number. A flat poststall lift curve as seen in the full-span test results is considered to be beneficial when the blades are operating in the neighborhood of the stall angle for lower speed, unsteady winds.

Duke Scholars

Author Laurens E. Howle Thomas Lord Department of Mechanical Engineering and Materia ...