Control of the Three-Dimensionalization of a Tollmien-Schlichting Wave using a Small Vibrating Device

The three dimensionalization process of a boundary layer transition is investigated by wind tunnel experiments. Attempts to generate velocity fluctuations similar to those which appear in the later stages of transition are carried out using a vibrating wire. The wire, with a diameter of about 30% of the displacement thickness, is attached to the surface wall in the spanwise direction, and is forced to vibrate back and forth in the streamwise direction. It is shown that this method is capable of generating a Tollmien-Schlichting wave (T-S wave) and an oblique wave in a flat-plate boundary layer.