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Aero-acoustic design and test of a multiple splitter exhaust noise suppressor for a 0.914m diameter lift fanA lift fan exhaust suppression system to meet future VTOL aircraft noise goals was designed and tested. The test vehicle was a 1.3 pressure ratio, 36 inch (91.44 cm) diameter lift fan with two chord rotor to stator spacing. A two splitter fan exhaust suppression system thirty inches (76.2 cm) long achieved 10 PNdB exhaust suppression in the aft quadrant compared to a design value of 20 PNdB. It was found that a broadband noise floor limited the realizable suppression. An analytical investigation of broadband noise generated by flow over the treatment surfaces provided very good agreement with the measured suppression levels and noise floor sound power levels. A fan thrust decrement of 22% was measured for the fully suppressed configuration of which 11.1% was attributed to the exhaust suppression hardware.
Document ID
19730021080
Acquisition Source
Legacy CDMS
Document Type
Contractor Report (CR)
Authors
Stimpert, D. L. (General Electric Co. Cincinnati, OH, United States)
Date Acquired
September 2, 2013
Publication Date
January 1, 1973
Subject Category
Propulsion Systems
Report/Patent Number
R73AEG282
NASA-CR-121108
Accession Number
73N29812
Funding Number(s)
CONTRACT_GRANT: NAS3-15556
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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