University of California, Irvine
Aeroacoustics Lab

AEROACOUSTICS OF THREE-STREAM JETS

Sponsorhip:  Rolls-Royce Corp.

Advanced engine architectures for tactical aircraft include novel three-stream arrangements that enhance the efficiency and stability of the engine cycle.  The presence of a third exhaust stream offers a means to reshape the exhaust plume to reduce sound radiation in specific directions (for example, towards communities and/or aircraft carrier personnel).  The secondary stream may be similarly manipulated augment the effect.   A large parametric study has been conducted to explore the benefits of three-stream jets and identify promising low-noise concepts.  Reductions of up to 5 dB in effective perceived noise level have been measured.  

Publication: 

Papamoschou, D.,  Johnson, A.D., and Phong, V.,  "Aeroacoustics of Three-Stream High-Speed Jets from Coaxial and Asymmetric Nozzles," AIAA-2013-0007,  51st AIAA Aerospace Sciences Meeting, Grapevine, TX, Jan. 7-10, 2013.  (PDF)

 

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Conceptual design of the three-stream nozzle.   

 

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Detailed design of the three-stream nozzle.  Bypass ratios ranged from 0.2 to 0.4. 

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High-precision rapid prototyping has enabled the testing of a large number of configurations, including examples with eccentric secondary and tertiary ducts shown here.

 

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Example noise spectra of coaxial (red) and eccentric (blue) three-stream nozzles.


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