Patent ID: 6092990
Filing Date: 2000-07-25
Classification: B64C,Y02T,Y10S

Abstract:
An active control system for reducing blade-vortex-interaction (BVI) noise generated by a rotor blade, the rotor blade including an interior, a tip end, a root end, and an aerodynamic surface comprising a leading edge, a trailing edge, an upper surface, and a lower surface, the active control system comprising:a sensor assembly in close proximity to the rotor blade, the sensor assembly being adapted to detect a change in air pressure on the aerodynamic surface of the rotor blade near the leading edge of the rotor blade, the change in air pressure having a magnitude;a device for changing a lift generated by the rotor blade, the device being adapted to be activated to thereby change the lift of the rotor blade while the rotor blade is maintained at a constant rotational velocity, the device for changing a lift generated by the rotor blade comprising at least one aperture on the rotor blade and a diaphragm in the interior of the rotor blade, the diaphragm being adapted to be activated and moved between a first position and a second position at a frequency, whereby movement of the diaphragm from the first position to the second position pushes air out of the at least one aperture and movement of the diaphragm from the second position to the first position draws air into the at least one aperture; anda controller for activating the device upon the detected change in air pressure by the sensor assembly, the controller activating the device to change the lift of the rotor blade in order to introduce a compensating pressure onto the aerodynamic surface of the rotor blade, the compensating pressure being adapted to attenuate the magnitude of the change of air pressure.