A study on the mechanism of high‐lift generation by an insect wing in unsteady motion at small Reynolds number

Abstract

Abstract The aerodynamic force and flow structure of a wing performing an unsteady motion at small Reynolds number ( Re =4000) is calculated by solving Navier–Stokes equations. Calculations were conducted for steady motion, simple unsteady motions suc as azimuth rotation, pure translation, feathering, etc., which can provide a basis for understanding the more complicated hovering flight. At Re =4000, the delayed stall mechanism was noted during the azimuth rotation of a wing due to span wise flow. In azimuth rotation and pure translation, large value of C L could be achieved due to fast acceleration of the airfoil from rest. Large value of C L could be maintained during azimuth rotation for many chord length of travel in comparison with the pure translation due to spanwise flow that causes Dynamic Stall Vortex (DSV) to remain attached. For feathering motion, pitch oscillation motion was dominated by the azimuth rotation. Copyright © 2010 John Wiley & Sons, Ltd.