Wind Tunnel Modeling and Investigation of Aerodynamic Characteristics of Black-tailed Gull

Abstract

Aerodynamic characteristics of the black-tailed gull were investigated for two configurations in gentle and strong breezes. Firstly, the wing is twisted down, so the area of separation on the upper surface of the wing gradually expands and there is no sudden decrease in lift. Secondly, the crosswind characteristics change with the difference in shape. For flat wing configurations in gentle breeze, the rolling moment occurs such that the ventral side of the bird faces upwind, which can be called the dihedral effect for an upper-winged aircraft. While gull wing configurations in strong breeze, the rolling moment occurs such that the back side of the bird faces upwind, which can be called an active rolling control to keep flying straight. To confirm the flow around the wings, numerical analyses visualized the area where separations occurred. This study showed that by utilizing the 3D models of the bird, nondeformed models were analyzed to investigate the basic aerodynamic characteristics of the bird. In addition, by comparing the results with those of the experiments on the taxidermy bird, it will be possible to confirm the effects of the deflection of the wings and the surface texture, and to approach morphing technology from the bird.