Active Control of Far-Field Noise from a Ducted Propeller

A feedforward control algorithm using a rpm reference signal and a rotor position signal was used to apply active noise control to reduce the far-field noise generated by a ducted propeller. This technique reduced the noise radiated from the plane wave and first circumferential (1, 0) spinning duct mode. Simultaneous cancellation of the blade passing frequency and the first harmonic was achieved. These reductions were obtained over a wide range of far-field angles with no increase in noise at other frequencies.