An active wave-cancellation system is designed to cancel 2D- and 3D-disturbances in a 2D-boundary layer taking into account the angle dependency of the dispersion relation of the Tollmien-Schlichting instability waves. Requirements to such a system are specified. The system is tested by exposure to both, ‘naturally’ occurring disturbances and artificially introduced point source disturbances. Up to 22 dB reduction of the ‘naturally’ occurring disturbances is obtained, but only minor additional improvement is achieved when the angle dependence of the dispersion is considered in the control system. On the other hand the range of the controllable lateral wavenumbers has been enlarged by these additional efforts as demonstrated with the point source disturbances. The performance of the system is limited by different acoustic effects due to the detection and generation of acoustic velocity and pressure fluctuations by the system.

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