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Jet noise characteristics of unsuppressed duct burning turbofan exhaust systemRecent aero-acoustic tests of model coannular nozzles have shown that less noise is generated if the higher-velocity jet is exhausted from the outer annular passage rather than from the primary nozzle. These findings are of particular significance to a duct-burning turbofan (DBTF) engine being studied for application to an advanced supersonic transport. Unlike conventional turbofan engines that have peak velocities from the primary nozzle, it is possible to design a DBTF engine to have a fan velocity higher than that of the primary flow. Results are presented for a NASA-sponsored model test program that covers a range of fan to primary-area ratios from 0.75 to 1.2, and a range of fan to primary-velocity ratios from 0.4 to 2.8. Correlations are given that relate radiated sound power to fan velocity, fan to primary-velocity ratio, and fan to primary-area ratio. Corresponding exhaust-plume velocity-traverse data are presented which suggest that the observed noise benefits may be due to the more rapid decay of the annular flow because of shear stresses on the inner surface that result from the lower-velocity primary flow.
Document ID
19760037965
Acquisition Source
Legacy CDMS
Document Type
Conference Paper
Authors
Packman, A. B.
(NASA Lewis Research Center Cleveland, OH, United States)
Kozlowski, H.
(United Technologies Corp. Pratt and Whitney Aircraft Div., East Hartford, Conn., United States)
Gutierrez, O.
(NASA Lewis Research Center Cleveland, Ohio, United States)
Date Acquired
August 8, 2013
Publication Date
January 1, 1976
Subject Category
Aircraft Propulsion And Power
Report/Patent Number
AIAA PAPER 76-149
Meeting Information
Meeting: Aerospace Sciences Meeting
Location: Washington, DC
Start Date: January 26, 1976
End Date: January 28, 1976
Sponsors: American Institute of Aeronautics and Astronautics
Accession Number
76A20931
Funding Number(s)
CONTRACT_GRANT: NAS3-17866
Distribution Limits
Public
Copyright
Other

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