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Effects of nozzle-exit boundary-layer conditions on excitability of heated free jetsThis paper reports an experimental study on the effects of nozzle-exit boundary-layer conditions on the excitability of heated free jets. The results were obtained at a Mach number 0.8 and total temperatures of 300 K and 670 K. External acoustic excitation was used to excite the jet. The excitation frequencies ranged up to 6 KHZ and the excitation levels were up to 150 dB. A level of 147 dB was used for most of the test points. Nozzle-exit boundary-layer characteristics were controlled by boundary layer tripping upstream of the nozzle exit plane. It has been shown that the free jet mixing rate strongly depends on the boundary-layer characteristics at the nozzle exit. Further, it appears that jets with a thin laminar nozzle-exit boundary layer are more selective about the optimum excitation frequency than those with a thick turbulent nozzle-exit boundary layer. Finally, for the jet of Mach number 0.8, it appears that free jet mixing and development may be controlled by flow excitation as well as by nozzle-exit boundary-layer modifications.
Document ID
19880032955
Acquisition Source
Legacy CDMS
Document Type
Conference Paper
Authors
Lepicovsky, J.
(Lockheed-Georgia Co. Marietta, GA, United States)
Brown, W. H.
(Lockheed Aeronautical Systems Co. Georgia Div., Marietta, United States)
Date Acquired
August 13, 2013
Publication Date
October 1, 1987
Subject Category
Fluid Mechanics And Heat Transfer
Report/Patent Number
AIAA PAPER 87-2723
Accession Number
88A20182
Funding Number(s)
CONTRACT_GRANT: NAS3-23708
Distribution Limits
Public
Copyright
Other

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