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Pipe jet noise reduction using co-axial swirl pipe
Published in Cambridge University Press
2017
Volume: 121
   
Issue: 1238
Pages: 488 - 514
Abstract
The present experimental work highlights the acoustic far field and flow field characteristics of confined co-axial swirling pipe jets. Co-axial confinements with six vanes at angles of 0°, 20° and 40° are considered here. Two pipe lengths of L/D=0.5 and 2 are studied. The Mach numbers studied range from 0.85 to 1.83. An increase in the pipe length causes suppression of the transonic tones in non-swirl pipe jets. Swirl reduces the low frequency noise components and increases the high-frequency components compared to non-swirl jet. The broadband shock associated noise is mitigated by the swirl pipe jets. However, the screech tone is completely eliminated by the swirl pipe jets. Further, swirl pipe jets radiate low levels of noise at all the emission angles compared to non-swirl pipe jets, for both the pipe length cases at supersonic Mach numbers. Increase in the pipe length enhances the shock associated noise and OASPL for the non-swirl pipe jet. Centreline pitot survey and schlieren visualisation show a reduction in core length, reduction in the number of shock cells, weakening/destruction of the shock cells by the swirl pipe jets compared to the non-swirl pipe jets. © Copyright Royal Aeronautical Society 2017.
About the journal
JournalData powered by TypesetAeronautical Journal
PublisherData powered by TypesetCambridge University Press
ISSN00019240
Open AccessNo
Concepts (14)
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    Acoustic noise measurement
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    Aerodynamics
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    Mach number
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    Noise abatement
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    Supersonic aerodynamics
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    Co-axial
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    Flow field characteristics
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    High frequency components
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    Jet noise reduction
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    Low-frequency noise
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    PIPE JET
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    SHOCK ASSOCIATED NOISE
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    SWIRL FLOW
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    Fighter aircraft