The aim of this study is to develop a method to control two-dimensional Tollmien-Schlichting wave (T-S wave) and oblique wave at the early stage of transition of a flat-plate boundary layer. Small and thin piezo-ceramic (PZT) actuators are used as the control device. In this study, twelve actuators are attached in line in the spanwise direction on the flat-plate surface and wired inde-pendently from each other. These actuators are used to generate a wave with the same amplitude and opposite sign of the incoming wave in Order to cancel it. From the experimental results, it is found that the cancel-lation of the velocity fluctuation is successful while the sweep angle of target wave is small. However, as the sweep angle be-comes larger, the canceling effect becomes insufficient in some spanwise locations even when the phases and the amplitudes of the controlling Signals are fine-tuned. It is also shown that the difficulty in the fine-tuning is due to the deformation of the velocity fluctuation pattern introduced by each actuator.
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