Effect of 3-Dimensional Airfoil Shape on Unsteady Fluid Forces in Pitching Motion

Abstract

A quasi-steady-state approach towards predicting the fluid forces acting on a hand under unsteady conditions yielded errors. The actual motion of a hand in swimming is obviously unsteady, and time-dependent fluid forces must be considered. The purpose of this study is to investigate the relationship between unsteady fluid forces and the vortex behaviors of a three-dimensional airfoil during pitch-oscillating motion. A flow visualization technique was used to examine the flow field near the airfoil edge in a wind tunnel test. The unsteady fluid forces were affected by the shedding behavior of vortices from the airfoil edge during the pitching oscillation, and the flow structure due to the vortex behavior was strongly affected by the reduced frequency.