AN EXPERIMENTAL INVESTIGATION OF THE UNSTEADY WAKE BEHIND AN OSCILLATING WING IN TWO-DIMENSIONAL, INCOMPRESSIBLE NON-CAVITATING FLOW.
PENNSYLVANIA STATE UNIV UNIVERSITY PARK ORDNANCE RESEARCH LAB
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A study of the wake produced by an oscillating wing in a two-dimensional noncavitating flow was conducted in a water tunnel using small air bubbles as flow tracers. High-speed motion pictures were taken of the air bubble motion in the wake and near the trailing edge of the wing while it was oscillating in a pitching motion about the quarter-chord. Films were taken for reduced frequencies from 0.5 to 1.7. Two mean angles of attack and two amplitudes of oscillation were studied. Velocity measurements in the wake were made for one film. The flow at the trailing edge was observed to be tangential for low mean angles of attack only. The vorticity rolling-up process in the wake differed from the nonlinear inviscid lifting body theory in two ways the vorticity rolled up into two or three line vortices for each half-wavelength in the wake, and the vorticity convection in the wake was retarded. Author
- Fluid Mechanics