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Radially leaned outlet guide vanes for fan source noise reductionTwo quiet engine program half scale fans one with a subsonic and the other with a supersonic fan tip speed at takeoff were run with 30 degree leaned and radial outlet guide vanes. Acoustic data at takeoff fan speed on the subsonic tip speed fan showed decreases in 200-foot sideline noise of from 1 to 2 PNdb. The supersonic tip speed fan a takeoff fan speed, however, showed noise increases of up 3 PNdb and a decrease in fan efficiency. At approach fan speed, the subsonic tip speed fan showed a noise decrease of 2.3 PNdb at the 200-foot sideline maximum angle and an increase in efficiency. The supersonic tip speed fan showed noise increase of 3.5 PNdb and no change in efficiency. The decrease in fan efficiency and the nature of the noise increase largely high frequency broadband noise lead to the speculation that an aerodynamic problem occurred.
Document ID
19740003484
Acquisition Source
Legacy CDMS
Document Type
Contractor Report (CR)
Authors
Kazin, S. B. (General Electric Co. Cincinnati, OH, United States)
Date Acquired
September 3, 2013
Publication Date
November 1, 1973
Subject Category
Propulsion Systems
Report/Patent Number
R73AEG176
NASA-CR-134486
Accession Number
74N11597
Funding Number(s)
CONTRACT_GRANT: NAS3-12430
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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