Response of a flat plate wing to a transverse gust at low reynolds numbers

Abstract

© 2018, American Institute of Aeronautics and Astronautics Inc, AIAA. All rights reserved. In this article the unsteady response of a flat plate wing encountering a transverse gust is presented. The aim of this study is to understand how the lift and drag forces of a wing respond to a large amplitude wind gust of magnitude equivalent to the flight speed and at Reynolds numbers relevant to biological fliers and unmanned aerial vehicles. A gust rig capable of generating large amplitude top-hat shaped gust profiles was constructed in a towing tank to replicate the ideal ’sharp edge’ Kussner gust. In addition, a new technique that enables vibration rejection from unsteady force measurements through improved kinematic measurements with inertial sensors is described. Measurements show that for a gust ratio of 1, a leading edge vortex forms on entry into the gust and vorticity is shed at the trailing edge in a planar manner. Large deformation of the gust shear layers is visible on wing entry, despite which linear theory is found to fit force measurements surprisingly well. Discernible differences, however, arise upon exit of the gust.