Lift Production on Flapping and Rotary Wings at Low Reynolds Numbers
Technical Report,15 May 2012,14 Nov 2015
University of Maryland College Park United States
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The objective of this research was to identify the mechanisms of lift production on models of an entomological flapping wing stroke by evaluating the relative importance of the leading edge vortex, other coherent vortical structures in the flow, bound circulation, and non-circulatory forcing. The entomological wing stroke was modeled as a combination of wing pitch and rotation. In collaboration with the NATO AVT-202 task group on Extensions of Fundamental Flow Physics to Practical MAV Aerodynamics, the rectilinear analogs of these rotational motions were also studied. By comparing both pitching and surging wings in rectilinear and rotational motion over a range of accelerations, it was found that the strength and trajectory of the leading edge vortex had a significant impact on the lift production of a wing undergoing highly unsteady kinematics. The vortex need not be attached to the wing to affect a lift force.