Bio-Inspired Sinusoidal Leading-Edged Wings

Abstract

Observations of maneuvering humpback whales have revealed unique hydrodynamic performance hypothesized to be a result of tubercles on the leading-edge of the whales' pectoral flippers. Inspired by this biological observation, it is shown sinusoidal leading-edge wings prevent the dramatic loss of lift caused by stall and instead generate a gradual decrease of lift with as much as 25% higher lift in the poststall regmine. Six different wing geometries, smooth and sinusoidal leading-edge models, swept and unswept configurations, were tested at angles of attack of -2 to 24 degrees at Reynolds numbers between 100,000-500,000. Oil surface flow visualization reveals variations in flow phenomena between the smooth and sinusoidal leading-edge configurations. Nomenclaturelift-to-drag ratio M = Mach number N = normal force n = sample size P = precision uncertainty P o = total pressure Re = Reynolds number q = dynamic pressure S = planform area S CL = standard deviation in coefficient of lift s = span t = student's t-value U = total uncertainty V ∞ = freestream velocity  = angle of attack  = boundary layer thickness  = ratio of specific heats  = wavelength of sinusoidal leading-edge

Comparative Investigation on Improved Aerodynamic and Acoustic Performance of Abnormal Rotors by Bionic Edge Design and Rational Material Selection

“…In contrast, it was also found that the sinusoidal structure applied on the leading edge will partially reduce the thrust of bionic rotors LE with PA 12 and Resin 9400, respectively. This is possibly due to the disturbance of flow distribution that arose by the sinusoidal structure near the leading edge [38]. Further, a more notable drop in the thrust of bionic rotor LE-TE-S with Resin 9400 can be found, resulting from the reduction of total effective lifting area by SMD, while the bionic rotor LE-TE-A with Resin 9400 showed a significant increase thrust during the whole speed range (3000-6000 rpm).…”