Experimental study on aerodynamic characteristics of unsteady wings at low Reynolds number

Aerodynamic forces and moment acting on wings of AR = 6 with heaving and feathering oscillations in a wind tunnel were measured at a low Reynolds number less than 10(4). Airfoils of the wings examined are not streamlined, but they are in various profiles such as a flat plate with and without sharp leading edge, circular are, and corrugated airfoils. By analyzing the sinusoidal aerodynamic forces and moment, it was found that some differences among airfoils were remarkable in both the mean values and the first harmonic amplitude of aerodynamic coefficients. A large perpendicular force is obtained in some airfoils, but the thrust was almost canceled by the drag in this low-Reynolds-number range during heaving motion alone. To get the maximum thrust, the optimal phase shift of combined heaving and feathering motion was required.