Investigation of the impulse action of a membrane on the straight wing boundary layer

The hot-wire anemometry technique is used to study the development of controlled disturbances in a straight wing boundary layer. Three-dimensional surface oscillations with large amplitude generate two types of disturbances: the localized longitudinal structures and wave packets. In downstream direction, the intensity of localized longitudinal structures decreases. The wave packets manifest themselves near the fronts of longitudinal localized structure in the flow region with adverse pressure gradient. In the separation flow area, an intensive growth of the wave packets amplitude is observed. The spatial development of the wave packets coincides with the development of three-dimen-sional Tollmien-Schlichting wave under similar conditions.