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Noise characteristics of model counter-rotating Prop-FansResults of acoustics tests of 24.5 in. diameter model counter-rotating propfans are presented. In these tests several configurations were investigated, including tractors and pushers downstream of a pylon, both at zero degrees and at four degrees angle-of-attack. The effects on noise of spacing between rotors and between the pylon and the rotors were also measured. Effects of rotor spacing were found to cause small changes in noise. Increasing blade count from 5-front and 5-rear to 6-front and 6-rear results in about a 1 EPNdB reduction in noise. Increasing only the front rotor blade count to six blades resulted in a noise reduction of about 2 EPNdB. The presence of the pylon resulted in a 1 EPNdB increase in noise. Angle of attack effects showed an increase of 3.5 EPNdB for the tractor configuration and only 1.5 EPNdB for the pusher configuration. Tip speed was found to be the strongest parameter in reducing noise. However, for a given thrust loading, an optimum tip speed is seen. Correlations between measurements and predictions are shown to be in good agreement.
Document ID
19880029299
Acquisition Source
Legacy CDMS
Document Type
Conference Paper
Authors
Magliozzi, B.
(United Technologies Corp. Hamilton Standard DIv., Windsor Locks, CT, United States)
Date Acquired
August 13, 2013
Publication Date
October 1, 1987
Subject Category
Acoustics
Report/Patent Number
AIAA PAPER 87-2656
Accession Number
88A16526
Funding Number(s)
CONTRACT_GRANT: NAS3-24222
Distribution Limits
Public
Copyright
Other

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