Stability experiments are conducted in the Arizona State University Unsteady Wind Tunnel on a 45 deg 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 mum rms finish. Under these conditions, natural stationary crossflow amplitudes are not measurable. This provides an ideal environment for measuring roughness-in-duced stationary crossflow. Spanwise arrays of 70-150 mum 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.
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