The effect of a wall normal vibration on a turbulent boundary layer

Abstract

This paper reports the results of an experimental investigation into the effect of a wall normal vibration on a zero pressure gradient turbulent boundary layer over a flat plate (690mm * 200mm * 12mm). Tests were conducted in a subsonic wind tunnel at 17m/s. An electromagnetic shaker, in conjunction with a vibration control system was used to supply and maintain a controlled sinusoidal plate oscillation. Phase averaged velocity profiles indicate that there is a negligible effect, due to vibration, on the mean boundary layer properties. Phase dependency plots show that Delta* and Theta exhibit a weak phase shift in relation to the plate vibration, whereas d is phase locked. Probability density distributions indicate a slight positive shift in velocity distribution for the 80Hz test case. Analysis in the frequency domain shows that the overall disturbance effect is limited to a very narrow bandwidth centered on the plate vibration frequency.