Equivalence ratio gradient effects on flame front topology in a stratified iso-octane/air turbulent V-flame

Vena, Patrizio; Deschamps, B.; Smallwood, Gregory J.; Johnson, Matthew R.

doi:10.1016/j.proci.2010.06.041

Cited by 35 publications

(29 citation statements)

References 28 publications

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“…The main effects of stratification observed were changes to the velocity field, with burned gases being accelerated towards the flame front opposite the stratified zone. Vena et al [22] examined the effects of equivalence ratio gradients on the topology of flame fronts in a turbulent iso-octane/air V-flame. They observed variations in curvature distributions that were less significant than those reported elsewhere in the methane/air literature.…”

Section: Introductionmentioning

confidence: 99%

The structure of premixed and stratified low turbulence flames

Sweeney

Hochgreb

Barlow

2011

Combustion and Flame

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Section: Introductionmentioning

confidence: 99%

The structure of premixed and stratified low turbulence flames

Sweeney

Hochgreb

Barlow

2011

Combustion and Flame

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“…The surface density function and thermal scalar dissipation rate showed negligible effects of stratification. The PDFs of curvature were dominated by turbulence for both nonswirling and swirling cases with little sensitivity to stratification, consistent with [47].…”

Section: Change In Flame Structure and Topologysupporting

confidence: 76%

“…flame length and wrinkling scales [4,16,17,29,30,[39][40][41][42][43][44][45][46]; flame surface density [31,34,45,47,48]; and curvature [29][30][31][32][33][34][35]41,[45][46][47]. The major contributions to the literature are summarized in Table 1.2 and subdivided based on flame configuration.…”

Section: Change In Flame Structure and Topologymentioning

confidence: 99%

“…Experiments on rod-stabilized V-flames [29][30][31]36,38,[42][43][44][45]47,48,50] have shown a change in flame structure and general increase in wrinkling for flames stabilized in transverse gradients in equivalence ratio. Robin et al [29] concluded that the effect of stratification-induced stretch was nonnegligible and observed a reduction in the normalized thickness of stratified flames relative to that of homogeneous flames of the same local equivalence ratio.…”

Section: Change In Flame Structure and Topologymentioning

confidence: 99%

“…In [47] we proposed a different method of quantifying the specific effects of large-scale, mean gradients in equivalence ratio on the local behaviour of stratified flames. Tracer PLIF of 3-pentanone was used to generate conditioned iso-contours of equivalence ratio up to the mean position of the flame front at c = 0.5, where c is the reactant progress variable.…”

Section: Change In Flame Structure and Topologymentioning

confidence: 99%

See 2 more Smart Citations

Equivalence Ratio Gradient Effects on Local Flame Front Topology and Heat Release Rate in Stratified, Iso-Octane/Air Turbulent V-Flames

Vena¹

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This thesis details the development and application of an experimental apparatus and methodology capable of quantifying the effects of partial premixing on the local behaviour of turbulent flames. A novel rectangular slot burner was used to generate controlled, transverse variations in mixture strength along its exit plane, such that turbulent, rod-stabilized V-flames could be anchored in reactant mixtures of varying mean gradients in equivalence ratio. A unique windowing approach was devised in which 3-pentanone tracer planar laser induced fluorescence (PLIF) of the reactants was used to determine an analysis region of interest (ROI) within the flame. Iso-contours of equivalence ratio (e.g.  = 0.95-1.05 for nearstoichiometric flame regions) were traced up to the mean position of the flame front to define the width of the ROI, which was specific to each mean  gradient flame condition. This analysis methodology enabled fair comparison among gradient settings, and ensured that any observed variation in local flame behaviour could be attributed specifically to mean  gradient effects, rather than simple mixture strength effects.To all my friends, starting from l

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Effects of Mixture Distribution on the Structure and Propagation of Turbulent Stratified Slot-Jet Flames

Brearley

Ahmed

Chakraborty

2023

Flow Turbulence Combust

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The influence of mixture stratification on the development of turbulent flames in a slot-jet configuration has been analysed using Direct Numerical Simulation data. Mixture stratification was imposed at the inlet by varying the equivalence ratio between 0.6 and 1.0 with different alignments to the reaction progress variable gradient: aligned gradients (back-supported), opposed gradients (front-supported) and misaligned gradients. An additional premixed case with a global equivalence ratio of 0.8 was simulated for comparison. The flame is shortest for the front-supported case, followed by the premixed flame, with the back-supported and misaligned gradient flames being the tallest and of comparable size. This behaviour has been explained in terms of the variations of the mean equivalence ratio within the flame and the volume-integrated reaction rate in the streamwise direction. The difference in mixture composition for these cases results in significant variations in the burning rate, flame area, flame wrinkling and flame brush thickness in the streamwise direction. The globally front-supported case has the highest volume-integrated burning rate and flame area, while the back-supported case has the lowest. The misaligned scalar gradient case exhibits qualitatively similar behaviour to that of the globally back-supported case. The burning intensity is unity for a major part of the flame length but assumes values greater than unity towards the flame tip where the effects of flame curvature become strong. All cases predominantly exhibit the premixed mode of combustion within the flamelet regime, so flamelet assumption-based reaction rate closures, originally proposed for premixed combustion, were evaluated using a priori analysis. The terms which require improved closures have been identified and existing closures have been improved where necessary. It was found that the global nature of mixture stratification does not influence the performance of the mean reaction rate closures or the parameterisation of marginal probability density functions of scalars in turbulent stratified mixture combustion.

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Equivalence ratio gradient effects on flame front topology in a stratified iso-octane/air turbulent V-flame

Cited by 35 publications

References 28 publications

The structure of premixed and stratified low turbulence flames

The structure of premixed and stratified low turbulence flames

Equivalence Ratio Gradient Effects on Local Flame Front Topology and Heat Release Rate in Stratified, Iso-Octane/Air Turbulent V-Flames

Effects of Mixture Distribution on the Structure and Propagation of Turbulent Stratified Slot-Jet Flames

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