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Near- and far-field acoustic measurements for stepped nozzles at over- and perfectly-expanded supersonic jet flow conditions

Near- and far-field acoustic measurements for stepped nozzles at over- and perfectly-expanded supersonic jet flow conditions
Near- and far-field acoustic measurements for stepped nozzles at over- and perfectly-expanded supersonic jet flow conditions
Detailed near- and far-field acoustic measurements were conducted for two circular stepped nozzles with 30 deg and 60 deg design inclinations at over- and perfectly-expanded supersonic jet flow conditions and compared to those for a circular nonstepped nozzle. Far-field acoustic results show that stepped nozzles play an insignificant role in altering noise emissions at perfectly expanded condition. At an over-expanded condition, however, the longer stepped nozzle produces significant noise reductions at the sideline and upstream quadrants, while the shorter stepped nozzle does not. Noise spectra analysis and Schlieren visualizations show that noise reduction can be primarily attributed to mitigations in the broadband shock-associated noise (BSAN), due to the ability of the longer stepped nozzle in suppressing shock strengths at downstream region. Near-field acoustic measurements reveal that the source region, as well as the intensity of turbulent and shock noises, are highly sensitive to the stepped nozzle configuration. Furthermore, BSAN seems to be eliminated by the longer stepped nozzle in near-field region due to the shock structure modifications.
0098-2202
Wei, X F
6c22970d-629f-47a9-8501-369e746a67fc
Chua, L P
ed4f220c-71c3-44db-9479-eb42d3c56d79
Lu, Z B
c173a631-7999-4b2a-b93d-4fd5e90bba5b
Lim, Desmond
82a7e7e8-2ade-44f8-a342-a99c2b9339c4
Mariani, R
d7dc30ee-83ae-46d9-8ee8-a9370f7f00af
Cui, Y D
432f25aa-b68a-4cc7-b6a7-98f93e044e41
New, T.H.
f35405df-ad65-4b96-9d6b-06afebdd43a8
Wei, X F
6c22970d-629f-47a9-8501-369e746a67fc
Chua, L P
ed4f220c-71c3-44db-9479-eb42d3c56d79
Lu, Z B
c173a631-7999-4b2a-b93d-4fd5e90bba5b
Lim, Desmond
82a7e7e8-2ade-44f8-a342-a99c2b9339c4
Mariani, R
d7dc30ee-83ae-46d9-8ee8-a9370f7f00af
Cui, Y D
432f25aa-b68a-4cc7-b6a7-98f93e044e41
New, T.H.
f35405df-ad65-4b96-9d6b-06afebdd43a8

Wei, X F, Chua, L P, Lu, Z B, Lim, Desmond, Mariani, R, Cui, Y D and New, T.H. (2020) Near- and far-field acoustic measurements for stepped nozzles at over- and perfectly-expanded supersonic jet flow conditions. Journal of Fluids Engineering, 142 (11), [111205]. (doi:10.1115/1.4047802).

Record type: Article

Abstract

Detailed near- and far-field acoustic measurements were conducted for two circular stepped nozzles with 30 deg and 60 deg design inclinations at over- and perfectly-expanded supersonic jet flow conditions and compared to those for a circular nonstepped nozzle. Far-field acoustic results show that stepped nozzles play an insignificant role in altering noise emissions at perfectly expanded condition. At an over-expanded condition, however, the longer stepped nozzle produces significant noise reductions at the sideline and upstream quadrants, while the shorter stepped nozzle does not. Noise spectra analysis and Schlieren visualizations show that noise reduction can be primarily attributed to mitigations in the broadband shock-associated noise (BSAN), due to the ability of the longer stepped nozzle in suppressing shock strengths at downstream region. Near-field acoustic measurements reveal that the source region, as well as the intensity of turbulent and shock noises, are highly sensitive to the stepped nozzle configuration. Furthermore, BSAN seems to be eliminated by the longer stepped nozzle in near-field region due to the shock structure modifications.

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More information

e-pub ahead of print date: 7 August 2020
Published date: 1 November 2020
Additional Information: Copyright VC 2020 by ASME

Identifiers

Local EPrints ID: 469262
URI: http://eprints.soton.ac.uk/id/eprint/469262
ISSN: 0098-2202
PURE UUID: 9bf08eab-264e-4f01-8f81-0b03ad7bc433
ORCID for Desmond Lim: ORCID iD orcid.org/0000-0001-6191-6803

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Date deposited: 12 Sep 2022 16:34
Last modified: 16 Mar 2024 21:04

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Contributors

Author: X F Wei
Author: L P Chua
Author: Z B Lu
Author: Desmond Lim ORCID iD
Author: R Mariani
Author: Y D Cui
Author: T.H. New

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