Experimental and Numerical Study on Aerodynamic Characteristics of a Flapping Wing with Angled Cross-Section

Bumblebees change their airfoils during a flapping cycle by rotating the hinges connecting the fore- and hindwings. Therefore, the instantaneous airfoil becomes an angled cross section like L-shape with a large camber. In this study, we experimentally and numerically investigated the aerodynamic characteristics of a flapping wing with angled cross sections. We measured unsteady aerodynamic force applied on a flapping wing with angled cross sections by using a scaled mechanical model in water tunnel. In addition, we conducted a numerical simulation of a flapping wing with angled cross section by using 3D Navier-Stokes code. The comparison between the experimental and numerical results shows a good agreement. As a result, the time-averaged lift for the angled flapping wings was inferior to that of the rigid flat plate. However, the instantaneous maximum lift for an appropriate angled cross section increases 32% larger than that of the flat plate at the center of the upstroke, when the wing has a positive camber.