Modulation of a methane Bunsen flame by upstream perturbations

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Abstract

In this paper the effects of an upstream spatially periodic modulation acting on a turbulent Bunsen flame are investigated using direct numerical simulations of the Navier-Stokes equations coupled with the flamelet generated manifold (FGM) method to parameterise the chemistry. The premixed Bunsen flame is spatially agitated with a set of coherent large-scale structures of specific wave-number, K. The response of the premixed flame to the external modulation is characterised in terms of time-averaged properties, e.g. the average flame height ⟨H⟩ and the flame surface wrinkling ⟨W⟩. Results show that the flame response is notably selective to the size of the length scales used for agitation. For example, both flame quantities ⟨H⟩ and ⟨W⟩ present an optimal response, in comparison with an unmodulated flame, when the modulation scale is set to relatively low wave-numbers, 4π/L ≲ K ≲ 6π/L, where L is a characteristic scale. At the agitation scales where the optimal response is observed, the average flame height, ⟨H⟩, takes a clearly defined minimal value while the surface wrinkling, ⟨W⟩, presents an increase by more than a factor of 2 in comparison with the unmodulated reference case. Combined, these two response quantities indicate that there is an optimal scale for flame agitation and intensification of combustion rates in turbulent Bunsen flames.

LanguageEnglish
Pages316-337
Number of pages22
JournalJournal of Turbulence
Volume18
Issue number4
DOIs
StatePublished - 3 Apr 2017

Fingerprint

upstream
flames
Methane
methane
Modulation
modulation
perturbation
agitation
wrinkling
Direct numerical simulation
turbulent flames
premixed flames
Navier Stokes equations
direct numerical simulation
Navier-Stokes equation
chemistry

Keywords

  • combustion
  • large-scale modulation
  • Turbulence control

Cite this

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title = "Modulation of a methane Bunsen flame by upstream perturbations",
abstract = "In this paper the effects of an upstream spatially periodic modulation acting on a turbulent Bunsen flame are investigated using direct numerical simulations of the Navier-Stokes equations coupled with the flamelet generated manifold (FGM) method to parameterise the chemistry. The premixed Bunsen flame is spatially agitated with a set of coherent large-scale structures of specific wave-number, K. The response of the premixed flame to the external modulation is characterised in terms of time-averaged properties, e.g. the average flame height ⟨H⟩ and the flame surface wrinkling ⟨W⟩. Results show that the flame response is notably selective to the size of the length scales used for agitation. For example, both flame quantities ⟨H⟩ and ⟨W⟩ present an optimal response, in comparison with an unmodulated flame, when the modulation scale is set to relatively low wave-numbers, 4π/L ≲ K ≲ 6π/L, where L is a characteristic scale. At the agitation scales where the optimal response is observed, the average flame height, ⟨H⟩, takes a clearly defined minimal value while the surface wrinkling, ⟨W⟩, presents an increase by more than a factor of 2 in comparison with the unmodulated reference case. Combined, these two response quantities indicate that there is an optimal scale for flame agitation and intensification of combustion rates in turbulent Bunsen flames.",
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Modulation of a methane Bunsen flame by upstream perturbations. / Cardoso de Souza, T.; Bastiaans, R.J.M.; De Goey, L.P.H.; Geurts, B.J.

In: Journal of Turbulence, Vol. 18, No. 4, 03.04.2017, p. 316-337.

Research output: Contribution to journalArticleAcademicpeer-review

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