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Couplings in a non-uniform compressible swirling jet with a modelled swirler.

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Title: Couplings in a non-uniform compressible swirling jet with a modelled swirler.
Authors: Varillon, Grégoire1,2 (AUTHOR) gregoire.varillon@univ-amu.fr, Kaiser, Thomas Ludwig2,3 (AUTHOR), Brokof, Philipp1,3 (AUTHOR), Weißbach, Dominik1 (AUTHOR), Oberleithner, Kilian2,3 (AUTHOR), Polifke, Wolfgang1,3 (AUTHOR)
Source: Journal of Fluid Mechanics. 5/10/2026, Vol. 1034, p1-31. 31p.
Subjects: Swirling flow, Wave amplification, Flow instability, Stability theory
Abstract: We give evidence of non-modal amplification mechanisms driven by swirl intensity from a bi-global linear analysis of a cold swirling flow representative of a premixed swirl burner: non-uniform, compressible, turbulent, enclosed and subject to vortex breakdown passed the expansion. The monolithic computational approach embeds a realistic axisymmetric swirler model in the computational domain. The amplification mechanisms are identified by stability and resolvent analysis under variations of the length of the annular duct section and combustion chamber, the swirl intensity and the swirler position. While the spectrum is affected by changes in the length only, the gain of the resolvent strongly depends on the swirl intensity. The results suggest an acoustically dominated amplification in the combustion chamber and a non-modal hydrodynamic-dominated process driven by the swirl intensity. Inertial waves carrying swirl fluctuations play a key role in the latter. The results are complemented by a resolvent sensitivity analysis that identifies the tip of the inner recirculation region and the surrounding shear layer as a wavemaker region that drives at high swirl numbers the non-modal amplification. The sensitivity of that region also enables the transfer of azimuthal momentum perturbations to axial momentum, hence activating a longitudinal acoustic resonance from azimuthal fluctuations. [ABSTRACT FROM AUTHOR]
Copyright of Journal of Fluid Mechanics is the property of Cambridge University Press and its content may not be copied or emailed to multiple sites without the copyright holder's express written permission. Additionally, content may not be used with any artificial intelligence tools or machine learning technologies. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)
Database: Engineering Source
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Header DbId: egs
DbLabel: Engineering Source
An: 193952176
AccessLevel: 6
PubType: Academic Journal
PubTypeId: academicJournal
PreciseRelevancyScore: 0
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  Data: Couplings in a non-uniform compressible swirling jet with a modelled swirler.
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  Data: <searchLink fieldCode="AR" term="%22Varillon%2C+Grégoire%22">Varillon, Grégoire</searchLink><relatesTo>1,2</relatesTo> (AUTHOR)<i> gregoire.varillon@univ-amu.fr</i><br /><searchLink fieldCode="AR" term="%22Kaiser%2C+Thomas+Ludwig%22">Kaiser, Thomas Ludwig</searchLink><relatesTo>2,3</relatesTo> (AUTHOR)<br /><searchLink fieldCode="AR" term="%22Brokof%2C+Philipp%22">Brokof, Philipp</searchLink><relatesTo>1,3</relatesTo> (AUTHOR)<br /><searchLink fieldCode="AR" term="%22Weißbach%2C+Dominik%22">Weißbach, Dominik</searchLink><relatesTo>1</relatesTo> (AUTHOR)<br /><searchLink fieldCode="AR" term="%22Oberleithner%2C+Kilian%22">Oberleithner, Kilian</searchLink><relatesTo>2,3</relatesTo> (AUTHOR)<br /><searchLink fieldCode="AR" term="%22Polifke%2C+Wolfgang%22">Polifke, Wolfgang</searchLink><relatesTo>1,3</relatesTo> (AUTHOR)
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  Data: <searchLink fieldCode="JN" term="%22Journal+of+Fluid+Mechanics%22">Journal of Fluid Mechanics</searchLink>. 5/10/2026, Vol. 1034, p1-31. 31p.
– Name: Subject
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  Data: <searchLink fieldCode="DE" term="%22Swirling+flow%22">Swirling flow</searchLink><br /><searchLink fieldCode="DE" term="%22Wave+amplification%22">Wave amplification</searchLink><br /><searchLink fieldCode="DE" term="%22Flow+instability%22">Flow instability</searchLink><br /><searchLink fieldCode="DE" term="%22Stability+theory%22">Stability theory</searchLink>
– Name: Abstract
  Label: Abstract
  Group: Ab
  Data: We give evidence of non-modal amplification mechanisms driven by swirl intensity from a bi-global linear analysis of a cold swirling flow representative of a premixed swirl burner: non-uniform, compressible, turbulent, enclosed and subject to vortex breakdown passed the expansion. The monolithic computational approach embeds a realistic axisymmetric swirler model in the computational domain. The amplification mechanisms are identified by stability and resolvent analysis under variations of the length of the annular duct section and combustion chamber, the swirl intensity and the swirler position. While the spectrum is affected by changes in the length only, the gain of the resolvent strongly depends on the swirl intensity. The results suggest an acoustically dominated amplification in the combustion chamber and a non-modal hydrodynamic-dominated process driven by the swirl intensity. Inertial waves carrying swirl fluctuations play a key role in the latter. The results are complemented by a resolvent sensitivity analysis that identifies the tip of the inner recirculation region and the surrounding shear layer as a wavemaker region that drives at high swirl numbers the non-modal amplification. The sensitivity of that region also enables the transfer of azimuthal momentum perturbations to axial momentum, hence activating a longitudinal acoustic resonance from azimuthal fluctuations. [ABSTRACT FROM AUTHOR]
– Name: AbstractSuppliedCopyright
  Label:
  Group: Ab
  Data: <i>Copyright of Journal of Fluid Mechanics is the property of Cambridge University Press and its content may not be copied or emailed to multiple sites without the copyright holder's express written permission. Additionally, content may not be used with any artificial intelligence tools or machine learning technologies. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract.</i> (Copyright applies to all Abstracts.)
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RecordInfo BibRecord:
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      – Type: doi
        Value: 10.1017/jfm.2026.11497
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      – Code: eng
        Text: English
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        PageCount: 31
        StartPage: 1
    Subjects:
      – SubjectFull: Swirling flow
        Type: general
      – SubjectFull: Wave amplification
        Type: general
      – SubjectFull: Flow instability
        Type: general
      – SubjectFull: Stability theory
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      – TitleFull: Couplings in a non-uniform compressible swirling jet with a modelled swirler.
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            – D: 10
              M: 05
              Text: 5/10/2026
              Type: published
              Y: 2026
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              Value: 1034
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