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Geometry effects on STOL engine-over-the-wing acoustics with 5.1 slot nozzlesThe correspondence of far field acoustic trends with changes in the characteristics of the flow field at the wing trailing edge caused by alterations in the nozzle-wing geometry were determined for several STOL-OTW configurations. Nozzle roof angles of 10 to 40 deg were tested with and without cutback of the nozzle sidewalls. Three wing chord sizes were used: baseline (33 cm with flaps retracted), 2/3-baseline, and 3/2-baseline. Flap deflection angles of 20 and 60 deg were used. The nozzle locations were at 21 and 46-percent of chord. With increasing wing size the jet noise shielding benefits increased. With increasing nozzle roof angle, the jet velocity at the trailing edge was decreased, causing a decrease in trailing-edge and fluctuating lift noise. Cutback of the nozzle sides improved flow attachment and reduced far-field noise. The best flow attachment and least trailing-edge noise generally were obtained with a 40 deg external deflector configuration and a cutback nozzle with a 40 deg roof angle.
Document ID
19760004975
Acquisition Source
Legacy CDMS
Document Type
Conference Paper
Authors
Vonglahn, U. (NASA Lewis Research Center Cleveland, OH, United States)
Groesbeck, D. (NASA Lewis Research Center Cleveland, OH, United States)
Date Acquired
September 3, 2013
Publication Date
January 1, 1975
Subject Category
Aircraft Propulsion And Power
Report/Patent Number
NASA-TM-X-71820
E-8519
Meeting Information
Meeting: Meeting of the Acoust. Soc. of Am.
Location: San Francisco, CA
Country: United States
Start Date: November 4, 1975
End Date: November 7, 1975
Accession Number
76N12063
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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