Aeronautics and astronautics – Aircraft – heavier-than-air – Helicopter or auto-rotating wing sustained – i.e. – gyroplanes
Patent
1996-10-09
1998-09-29
Barefoot, Galen L.
Aeronautics and astronautics
Aircraft, heavier-than-air
Helicopter or auto-rotating wing sustained, i.e., gyroplanes
244207, 416 90A, 416 92, 415119, B64C 2700
Patent
active
058136258
ABSTRACT:
A pressurized porous surface near the leading edge of a rotorcraft blade, is designed to be used as an active control device which alleviates the aerodynamics of blade vortex interactions (BVI) and thus the impulsive BVI noise levels and signature. The pressurized porous surface can be actuated on an azimuth-dependent deployment schedule or actuated continuously. The pressurized porous surface is supplied with either positively pressurized air, negatively pressurized air, or a combination of both, when actuated. The pressurized porous surface targets the local blade aerodynamics, rather than the vortex strength or blade/vortex separation distance. This targeting can be achieved through use of negatively pressurized air (suction) blowing in a direction normal to the blade surface to reduce the rotor blade's effective thickness resulting in a smaller leading edge radius as perceived by the vortex wake, and positively pressurized air (blowing) to increase the effective thickness resulting in an increase in the leading edge radius of the blade.
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Domzalski David B.
Hassan Ahmed A.
Kennedy Dennis K.
Straub Friedrich K.
Barefoot Galen L.
McDonnell Douglas Helicopter Company
Mullins Kenton R.
Stout Donald E.
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