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Blade vortex interaction noise reduction techniques for a rotorcraftAn 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).
Document ID
20080004608
Acquisition Source
Langley Research Center
Document Type
Other - Patent
Authors
Charles, Bruce D.
Hassan, Ahmed A.
Tadghighi, Hormoz
JanakiRam, Ram D.
Sankar, Lakshmi N.
Date Acquired
August 24, 2013
Publication Date
January 27, 1998
Subject Category
Aircraft Design, Testing And Performance
Funding Number(s)
CONTRACT_GRANT: NAS1-19136
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.
Patent
US-PATENT-5,711,651
Patent Application
US-PATENT-APPL-SN-662601

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