Comparison of Rotating and Translating Wings: Force Production and Vortex Characteristics

Abstract

Experiments were conducted on a rectangular flat plate wing at high incidence to compare the force production and leading-edge vortex location and strength as a function of time for eight sets of wing kinematics: rectilinear and rotational pitch and surge, with fast and slow accelerations. The primary differences observed in the force histories were between the pitch and surge cases, and they occurred during the acceleration or pitching portions of the motions. The force histories were found to be similar between the rectilinear and rotational cases. The leading-edge vortex trajectories in the rectilinear cases were found to be similar when compared on a new time scale , related to the integrated leading-edge-normal velocity. The vortex trajectory of the rotational cases matched those of the rectilinear cases until the leading-edge vortex in the rotational case settled into a position attached to the wing. Circulation values of the leading-edge vortex for all cases were found to collapse when plotted versus and scaled by the instantaneous leading-edge-normal velocity. The results demonstrate a successful collapse of both vortex quantities and force production using only leading-edge kinematics.