2001 Volume 50 Pages 281-287
An Experimental attempt to reduce the aerodynamic noise generated at the cavity by controlling the wavelengths of velocity fluctuation patterns along the spanwise direction is carried out. As a result of the flow control using piezo-ceramic actuator pieces attached at the upstream-edge of the cavity, the system is able to generate wavy structures which have finite spanwise wavelengths and the dominant peak of the cavity noise can be successfully reduced, for the case when the upstream boundary layer is laminar. Controlling the flow to have longer spanwise wavelength is found to be more effective for noise reduction. However, when the upstream boundary layer is turbulent, although noise reduction can be achieved, an attempt to form the wavy pattern is unsuccessful.