A numerical study of laminar methane/air triple flames in two-dimensional mixing layers

Guo, Hongsheng; Liu, Fengshan; Smallwood, Gregory J.

doi:10.1016/j.ijthermalsci.2005.08.010

Cited by 15 publications

(5 citation statements)

References 26 publications

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“…This result was also confirmed by Ghosal and Vervisch (2000). Guo et al (2006), in a triple flame formed in methane=air mixing layers with three different mixture fraction gradients, showed that in the near stoichiometric mixture fraction region, the local burning flux of triple flame was lower when the mixing layer was narrower.…”

Section: Introductionsupporting

confidence: 60%

A Numerical Study of the Magnetic Influence on Coaxial Jets' Flow Upstream From Lifted Flames

Delmaere

Sarh

Gillon

2010

Combustion Science and Technology

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The authors conducted a numerical investigation of the laminar flow issuing from a methane/air coaxial burner submitted to a magnetic field. They intend to understand the mechanisms involved in the magnetic stabilization of the lifted flames. The model is based on the coupled equations of conservation of mass, species, and momentum in which the magnetic force acting on paramagnetic oxygen is introduced in the source term. A CFD code is used to solve the steady-state equations in an axisymmetric domain. Air jet velocity is shown to decrease locally in front of the magnetic gradient. Calculation of the stoichiometric radius reveals a lateral displacement of the stoichiometric line and a decrease of the fuel mass fraction gradient when the magnetic force is applied. These results explain the observed reduction of the liftoff height of flames under magnetic gradient due to an increase of the flame propagation velocity.

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Section: Introductionsupporting

confidence: 60%

A Numerical Study of the Magnetic Influence on Coaxial Jets' Flow Upstream From Lifted Flames

Delmaere

Sarh

Gillon

2010

Combustion Science and Technology

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“…This is due to the competing effects of reduced residence time at higher strain rates and enhanced interaction between the NP zone and the two premixed zones. As discussed by Guo et al, as the strain rate is increased, the physical separation between the reaction zones is reduced (cf. Figure ), which leads to enhanced interaction between the NP and two premixed reaction zone and, thus, slightly higher temperature for the strain rate of 250 s –1 .…”

Section: Resultsmentioning

confidence: 97%

Effect of Unsaturated Bond on NO_x and PAH Formation in n-Heptane and 1-Heptene Triple Flames

Aggarwal

Brezinsky

2013

Energy Fuels

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Various engine and shock tube studies have observed increased NO x emissions from the combustion of biodiesels relative to regular diesel and linked them to the degree of unsaturation or the number of double bonds in the molecular structure of long-chain biodiesel fuels. We report herein a numerical investigation on the structure and emission characteristics of triple flames burning n-heptane and 1-heptene fuels, which represent, respectively, the hydrocarbon side chain of the saturated (methyl octanoate) and unsaturated (methyl octenoate) biodiesel surrogates. Our objective is to examine the effect of unsaturated (double) bond on NO x and soot emissions in a flame environment containing regions of lean premixed, rich premixed, and nonpremixed combustion. A validated detailed kinetic model with 198 species and 4932 reactions was used to simulate triple flames in a counterflow configuration with different levels of premixing and strain rates. Results indicate that although the global structures of n-heptane and 1-heptene triple flames are quite similar, there are significant differences with respect to NO x and polycyclic aromatic hydrocarbon (PAH) emissions from these flames. The NO x production rates in the rich premixed, lean premixed, and nonpremixed zones are higher in 1-heptene flames than in n-heptane flames, and the differences become more pronounced as the level of premixing is increased. The NO x formed through the prompt, thermal, N2O, and NNH mechanisms is also higher in 1-heptene flames. NO x formation in the rich premixed zone is primarily due to the prompt NO, that in the nonpremixed zone is through the thermal NO, and that in the lean premixed zone is due to the NNH and N2O routes. The PAH species are mainly formed in the rich premixed zone, and their emissions are significantly higher in 1-heptene flames than in n-heptane flames. The reaction pathway analysis indicated that the dominant path for benzene formation involves the recombination of two propargyl (C3H3) radicals, and the presence of the double bond in 1-heptene provides a significant route for its production through the formation of C3H5. This path is not favored in the oxidation of n-heptane, as it decomposes directly to smaller alkyl radicals. Whereas the NO x and PAH emissions decrease with the increase in strain rate, they are consistently higher in 1-heptne flames than in n-heptane flames, irrespective of the strain rate.

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“…To identify the relative contributions of these two interactions, as in our previous studies [25,38] for triple flames, we did an extra simulation (ESIM) for the corresponding rich CFPF of Flame 2. In this extra simulation, the symmetrical boundary condition for the energy conservation equation on the stagnation plane was replaced by a fixed value that is the maximum temperature of Flame 2.…”

Section: No Formation In Two Typical Triple Flamesmentioning

confidence: 99%

A numerical investigation on NOX formation in counterflow n-heptane triple flames

Guo

Smallwood

2007

International Journal of Thermal Sciences

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/npsi/ctrl?action=rtdoc&an=6597458&lang=en http://nparc.cisti-icist.nrc-cnrc.gc.ca/npsi/ctrl?action=rtdoc&an=6597458&lang=frAccess and use of this website and the material on it are subject to the Terms and Conditions set forth at http://nparc.cisti-icist.nrc-cnrc.gc.ca/npsi/jsp/nparc_cp.jsp?lang=en NRC Publications Archive Archives des publications du CNRCThis publication could be one of several versions: author's original, accepted manuscript or the publisher's version. / La version de cette publication peut être l'une des suivantes : la version prépublication de l'auteur, la version acceptée du manuscrit ou la version de l'éditeur. For the publisher's version, please access the DOI link below./ Pour consulter la version de l'éditeur, utilisez le lien DOI ci-dessous.http://dx.doi.org/10.1016/j.ijthermalsci. 2006.11.002 International Journal of Thermal Sciences, 46, September, pp. 936-943, 2007 A numerical investigation on NOx formation in counterflow n-heptane triple flames Guo, Hongsheng; Smallwood, Gregory J. AbstractThe formation of NO X in counterflow n-heptane/air triple flames was investigated by numerical simulation. Detailed chemistry and complex thermal and transport properties were employed. The results indicate that a triple flame produces more NO and NO 2 than the corresponding premixed flames due to not only the appearance of the diffusion flame but also the interaction between different flame branches. The relative contributions of different routes to NO formation in the premixed flame branches change with the variation of the equivalence ratio, but the thermal mechanism always dominates in the diffusion flame branch. The interaction between flame branches is enhanced with the decrease of the distance between them. Both heat and radical exchange between flame branches contribute to the interaction. A new feature that does not exist in methane/air triple flame was observed in n-heptane/air triple flames, i.e. when the rich mixture equivalence ratio is higher, there are two peaks of CH concentration on the rich side of the diffusion flame branch, which leads to that some NO is formed beside the diffusion flame branch by the prompt route. Crown

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A numerical study of laminar methane/air triple flames in two-dimensional mixing layers

Cited by 15 publications

References 26 publications

A Numerical Study of the Magnetic Influence on Coaxial Jets' Flow Upstream From Lifted Flames

A Numerical Study of the Magnetic Influence on Coaxial Jets' Flow Upstream From Lifted Flames

Effect of Unsaturated Bond on NO_x and PAH Formation in n-Heptane and 1-Heptene Triple Flames

A numerical investigation on NOX formation in counterflow n-heptane triple flames

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A numerical study of laminar methane/air triple flames in two-dimensional mixing layers

Cited by 15 publications

References 26 publications

A Numerical Study of the Magnetic Influence on Coaxial Jets' Flow Upstream From Lifted Flames

A Numerical Study of the Magnetic Influence on Coaxial Jets' Flow Upstream From Lifted Flames

Effect of Unsaturated Bond on NOx and PAH Formation in n-Heptane and 1-Heptene Triple Flames

A numerical investigation on NOX formation in counterflow n-heptane triple flames

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Effect of Unsaturated Bond on NO_x and PAH Formation in n-Heptane and 1-Heptene Triple Flames