AN EXPERIMENTAL STUDY OF THE INFLUENCE OF LOCALIZED, NORMAL SURFACE OSCILLATIONS ON THE LAMINAR FLOW OVER A FLAT PLATE.
MICHIGAN UNIV ANN ARBOR
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The purpose of the investigation is to study the effect of a finite localized surface oscillation on the mean value velocity profiles in the laminar boundary layer of a flat plate and compare the results with an analytic solution. The experimental program consisted of the design, construction and testing of a flat plate with a flexible membrane located in the surface and driven by an oscillating device. The flat plate was located in a low turbulence, low speed wind tunnel. The principal measuring instrument was a hot wire anemometer. Experimental data was taken at free stream velocities of 20 and 40 feet per second. The surface oscillation amplitude was 0.050 inches and the frequency range 15 to 100 cycles per second. The results of the investigation show that a definite change in the mean value velocity profile in laminar flow occurs and is a function of free stream velocity, frequency and location on the plate surface. In addition, early transition is promoted despite the fact that the distbance test range was within the Tollmien-Schlichting stability area. The analytic solution is found to be qualitatively valid in the laminar flow region downstream of the membrane. Author
- Fluid Mechanics