Effect of Aspect Ratio on Aerodynamic Characteristics at Low Reynolds Numbers

The effect of the aspect ratio on the aerodynamic characteristics of rectangular wings is experimentally investigated at Reynolds numbers on the order of 104. The aerodynamic coefficients are analyzed based on visualized flowfields and theoretical results. The characteristics of high-aspect-ratio wings are shown to be affected by leading-edge separation bubbles at low Reynolds numbers. However, the qualitative characteristics are similar when the aspect ratio is 3.0 and above. The characteristics of wings with aspect ratios below 3.0 differ significantly from those of wings with large aspect ratios. In particular, a significant influence is revealed for aspect ratios of 1.0 and below. The effect of the aspect ratio is considered to be caused by wingtip vortices. The discussion also includes the effects of the Reynolds number, the shape of the leading edge, and the thickness ratio.