Development of stationary crossflow vortices on a swept wing

1994 by the American Institute of Aeronautics and Astronautics, Inc. All rights reserved. Stability experiments are conducted in the Arizona State University Unsteady Wind Tunnel on a 45 swept airfoil. The pressure gradient is designed so that both crossflow and Tollmien-Schlichting disturbances are weakly amplified. The surface of the airfoil is hand polished to a 0. 25 m rms finish. Under these conditions, natural stationary crossflow amplitudes are not measurable. This provides an ideal environment for measuring roughness-induced stationary crossflow. Spanwise arrays of 70-150 m roughness elements are introduced near the attachment line. These elements induce clearly defined stationary crossflow vortices downstream. Detailed hot-wire measurements are taken to document the growth and development of these vortices. Roughness spacing and Reynolds number are varied in order to examine the behavior of all amplified wavelengths. The measurements clearly show that traditional linear stability theory does not accurately predict the growth rates of stationary crossflow waves under these conditions.

Development of stationary crossflow vortices on a swept wing Conference Paper