Heat release rate variations in a globally stoichiometric, stratified iso-octane/air turbulent V-flame

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

doi:10.1016/j.combustflame.2014.09.019

Cited by 24 publications

(21 citation statements)

References 75 publications

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“…This follows from the fact that, in the higher negative curvature zone, the rate of occurrence of lower heat release rate increased indicating regions of flames close to local extinction along the flame front, as was discussed in [59]. On the other hand, increasing the turbulent Reynolds number Ret from 10 to 150 does not have much effect on the degree of scatter in the heat release rate.…”

Section: Cellular Flame Structure and Flame Accelerationmentioning

confidence: 61%

Effects of pressure on cellular flame structure of high hydrogen content lean premixed syngas spherical flames: A DNS study

Dinesh

Shalaby

Luo

et al. 2016

International Journal of Hydrogen Energy

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2016). Effects of pressure on cellular flame structure of high hydrogen content lean premixed syngas spherical flames: A DNS study. International Journal of Hydrogen Energy, 41(46), 21516-21531. DOI: 10.1016/j.ijhydene.2016 General rights Copyright and moral rights for the publications made accessible in the public portal are retained by the authors and/or other copyright owners and it is a condition of accessing publications that users recognise and abide by the legal requirements associated with these rights.• Users may download and print one copy of any publication from the public portal for the purpose of private study or research.• You may not further distribute the material or use it for any profit-making activity or commercial gain • You may freely distribute the URL identifying the publication in the public portal ? Take down policyIf you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim. The joint probability density functions of OH radical mass fraction and temperature show broadening OH values in the high temperature zone at elevated pressures compared to its distribution at the atmospheric pressure. Comparisons of mean species distributions of 3 OH and HO2 over temperature between laminar and turbulent flames show that pressure elevation has a major influence on the flame structure in the composition space.

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Section: Cellular Flame Structure and Flame Accelerationmentioning

confidence: 61%

Effects of pressure on cellular flame structure of high hydrogen content lean premixed syngas spherical flames: A DNS study

Dinesh

Shalaby

Luo

et al. 2016

International Journal of Hydrogen Energy

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“…Vagelopoulos and Frank [23] have demonstrated that the methylidyne radical (CH) follows heat release image reasonably well and can be used as a flame marker in undiluted methane flames at the stoichiometric condition. Various groups have also measured CH2O and OH radicals and found that product of OH and CH2O radicals correlates well with the HRR for turbulent premixed flames under various conditions including premixed flames approaching the blow-off conditions [24][25][26][27]. However, experiments are typically restricted to two-dimensional sections of the flame while the three-dimensional description of the flame generally requires three-dimensional numerical simulations.…”

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confidence: 99%

Heat release rate variations in high hydrogen content premixed syngas flames at elevated pressures: Effect of equivalence ratio

Dinesh

Shalaby

Luo

et al. 2017

International Journal of Hydrogen Energy

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Three-dimensional direct numerical simulations with detailed chemistry were conducted to investigate the effect of equivalence ratio on spatial variations of the heat release rate and flame markers of hydrogen/carbon monoxide syngas expanding spherical premixed flames under turbulent conditions at elevated pressures. The flame structures and the heat release rate were analysed in detail for fuel-lean, stoichiometric and fuel-rich centrally ignited spherical flames. The equivalence ratio changes the balance among thermodiffuive effects, Darrieus-Landau instability and turbulence, leading to different flame dynamics and the heat release rate distribution, despite exhibiting similar cellular and wrinkling flames. The Darrieus-Landau instability is relatively insensitive to the equivalence ratio while the thermo-diffuive process is strongly affected by the equivalence ratio. As the thermo-diffusive effect increases as the equivalence ratio increases, the fuel-lean flame is more unstable than the fuel-rich flame with the stoichiometric flame in between, under the joint effects of the Darrieus-Landau instability and the thermo-diffusive effect. The local heat release rate and curvature display a positive correlation for the lean flame, no correlation for the stoichiometric flame, and negative correlation for the rich flame. Furthermore, the low and high heat release rate values for the fuel-lean flame are found in the negative and positive curvature zones, respectively, while the oppostite trends are found in fuel-rich flame. It is found that heat release rate markers based on species concentrations vary strongly with changing equivalence ratio. The results suggest that the HCO concentration and product of OH and CH2O concentrations show good correlation with the local heat release rate for H2/CO syngas-air stoichiometric flame under turbulent conditions at elevated pressures.3

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“…Recent experiments [31][32][33][34]36,47,128] have highlighted the importance of clearly defining the question and approach with which the effects of partial premixing are quantified, where it is important to differentiate the general effects of stratification on the overall behaviour of a flame system from the specific effects of controlled experiments [21][22][23][24][25] and simulations [26,70,72,80] in which an equivalence ratio gradient can be imposed normal to flames propagating in a channel [22][23][24][25][26], to spherically-expanding laminar flames [21], or to stagnation flames [70,72,80]. In subsequent work, Böhm et al [46] used Rayleigh scattering and simultaneous OH and acetone PLIF to investigate variations in flame front thickness, curvature, and length with stratification.…”

Section: Introductionmentioning

confidence: 99%

“…In previous work by the present authors [47,128], a different but complementary approach was developed in which 3-pentanone tracer PLIF is used to identify mean conditioned iso-contours of equivalence ratio () up to the mean position of the flame-front at c = 0.5. Subsequent simultaneous OH and CH 2 O PLIF measurements were used to probe flame topology and heat release rates within similar  iso-contours for flame cases of differing mean  gradient.…”

Section: Introductionmentioning

confidence: 99%

“…By choosing an analysis region of interest (ROI) such that a constant mean range of  is evaluated as the  gradient is varied, it is possible to isolate specific gradient effects from those of varying mixture strength. This ROI approach has been applied to turbulent iso-octane/air V-flames in locally near-stoichiometric [47,128] flame regions. Results showed small but discernable variations in mean heat release rates among gradient conditions, and implied that "backsupport" from the heated products within the V-flame scaled with gradient [128], in line with the backsupport noted in flames subjected to gradients normal to the flame front in experiments [21][22][23][24][25] and simulations [26,70,72,80].…”

Section: Introductionmentioning

confidence: 99%

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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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Heat release rate variations in a globally stoichiometric, stratified iso-octane/air turbulent V-flame

Cited by 24 publications

References 75 publications

Effects of pressure on cellular flame structure of high hydrogen content lean premixed syngas spherical flames: A DNS study

Effects of pressure on cellular flame structure of high hydrogen content lean premixed syngas spherical flames: A DNS study

Heat release rate variations in high hydrogen content premixed syngas flames at elevated pressures: Effect of equivalence ratio

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

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