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An experimental study of helicopter rotor rotational noise in a wind tunnelThe rotational noise of model helicopter rotors in forward flight was studied in an anechoic wind tunnel. The parameters under study were the rotor thrust (blade loading), blade number and advance ratio. The separate effects of each parameter were identified with the other parameters being held constant. The directivity of the noise was also measured. Twelve sets of data for rotational noise as a function of frequency were compared with the theory of Lowson and Ollerhead. In general, the agreement is reasonably good, except for the cases of (1) low and high disk loadings, (2) the four bladed rotor, and (3) low advance ratios. The theory always under-estimates the rotational noise at high harmonics.
Document ID
19760055114
Acquisition Source
Legacy CDMS
Document Type
Conference Paper
Authors
Lee, A.
(Massachusetts Inst. of Tech. Cambridge, MA, United States)
Harris, W. L.
(Massachusetts Inst. of Tech. Cambridge, MA, United States)
Widnall, S. E.
(MIT Cambridge, Mass., United States)
Date Acquired
August 8, 2013
Publication Date
July 1, 1976
Subject Category
Acoustics
Report/Patent Number
AIAA PAPER 76-564
Meeting Information
Meeting: Aero-Acoustics Conference
Location: Palo Alto, CA
Start Date: July 20, 1976
End Date: July 23, 1976
Sponsors: American Institute of Aeronautics and Astronautics
Accession Number
76A38080
Funding Number(s)
CONTRACT_GRANT: NAS2-7684
Distribution Limits
Public
Copyright
Other

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