Welcome to the new version of CaltechAUTHORS. Login is currently restricted to library staff. If you notice any issues, please email coda@library.caltech.edu
Published January 2009 | Published
Conference Paper Open

Low Reynolds Number Wing Response to an Oscillating Freestream With and Without Feed Forward Control


The unsteady lift of a low Reynolds number wing in an oscillating freestream is documented in terms of its amplitude and phase. The phase variation of the lift relative to the freestream velocity shows a larger phase difference than predicted by classical unsteady flow theory. A constant time delay between the lift and the actuator was observed to be τ^+ = t_(delay)U/c = 5.3 when normalized by the freestream speed and chord. Feed forward control of pulsed-jet actuators is used to modulate the lift coefficient of the wing, in an attempt to suppress the lift oscillations. Suppression of the fluctuating lift at the fundamental frequency was partially successful, but additional "noise" was added to harmonics of the lift signal by the controller.

Additional Information

© 2009 by David R. Williams. Published by the American Institute of Aeronautics and Astronautics, Inc., with permission. Published Online: 15 Jun 2012. The support for this work by the U.S. Air Force Office of Scientific Research MURI (FA9550-05-0369) with program manager Dr. Fariba Fahroo is gratefully appreciated. We also acknowledge the support from the Illinois NASA Space Grant Consortium for Wes Kerstens.

Attached Files

Published - WilliamsQuachKerstensEtAl2009.pdf


Files (372.1 kB)
Name Size Download all
372.1 kB Preview Download

Additional details

August 20, 2023
October 20, 2023