Active control of wake/blade-row interaction noise

This paper describes an analytical/computational approach for controlling the noise generated by wake/blade row interaction through the use of antisound actuators on the blade surfaces. A representative two-dimensional section of a fan stage, composed of an upstream fan rotor and a downstream fan exit guide vane (FEGV), is examined. An existing model for the wakes generated by the rotor is analyzed to provide realistic magnitudes for the vortical excitations imposed at the inlet to the FEGV. The acoustic response of the FEGV is determined at multiples of the blade passing frequency by using the linearized unsteady flow analysis, LINFLO. An analysis then is presented to determine the complex amplitudes required for the control surface motions to best reduce the farfield noise