Aerodynamic Performance of Biological Airfoils

Experimental studies on static, non-flapping dragonfly wings have shown favorable aerodynamic performance at low Reynolds number (Re ≤ 10,000). High lift is hypothesized to arise from the dragonfly’s pleated wing structure. A numerical study of flow past a modeled dragonfly wing section as well as its comparison to a corresponding profiled airfoil and a flat plate were conducted at Re = 10,000. The main focus of the current investigation was to determine the primary flow features and mechanisms that are responsible for the enhanced performance of these biological wing sections at these relatively low Reynolds numbers. A time-accurate Cartesian grid based Navier-Stokes immersed boundary solver was utilized in the current study. The numerical results indicate that the pleated airfoil at a zero degree angle-of-attack generates the least drag despite its unconventional shape. Additionally, a higher transitory lift is produced by the pleated airfoil at a five degree angleof-attack when compared to the profiled airfoil.