The Boeing Company

Mcdonnell Douglas Helicopter Company

Bruce Dean Charles

Ahmed A Hassan

Hormoz Tadghighi

Ram Damaraju JanakiRam

Ram D Janakiram

Lakshmi N Sankar

David B Domzalski

A linear electromagnetic zero net mass jet (ZNMJ) actuator incorporating a pair of permanent magnets. The magnets are arranged such that an air gap is formed therebetween and further such that opposite poles of the magnets are arranged on opposite sides of the air gap. This concentrates the flux field across the air gap. A coil is disposed in the air gap. The coil is attached to a diaphragm which acts as a piston. When an electric current is applied to the coil, the flux field across the air gap causes a rapidly oscillating motion of the diaphragm. The actuator provides an increased rate of displacement of the piston as compared to single magnet ZNMJ actuators, and thus provides a higher momentum output across a broad frequency and voltage spectrum than conventional ZNMJ actuators using a single magnet.

Linear electromagnetic zero net mass jet actuator

An active control device for reducing blade-vortex interactions (BVI) noise generated by a rotorcraft, such as a helicopter, comprises a segmented trailing edge flap located near the tip of each of the rotorcraft's rotor blades. The various flap segments may be independently actuated according to flap deflections schedules which are tailored to address a particular operating regime with maximum efficiency and effectiveness. Through the careful azimuth-dependent independent actuation of the flap segments, blade tip vortices which are the primary source for BVI noise are (a) made weaker and (b) pushed farther away from the rotor disk (that is, larger blade-vortex separation distances are achieved), resulting in lower BVI noise.

Tapered/segmented flaps for rotor blade-vortex interaction (BVI) noise and vibration reduction

An active control device for reducing blade-vortex interactions (BVI) noise generated by a rotorcraft, such as a helicopter, comprises a trailing edge flap located near the tip of each of the rotorcraft's rotor blades. The flap may be actuated in any conventional way, and is scheduled to be actuated to a deflected position during rotation of the rotor blade through predetermined regions of the rotor azimuth, and is further scheduled to be actuated to a retracted position through the remaining regions of the rotor azimuth. Through the careful azimuth-dependent deployment and retraction of the flap over the rotor disk, blade tip vortices which are the primary source for BVI noise are (a) made weaker and (b) pushed farther away from the rotor disk (that is, larger blade-vortex separation distances are achieved).

Blade vortex interaction noise reduction techniques for a rotorcraft

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Mesa, AZ, United States of America

Bruce Dean Charles