Effects of equivalence ratio variation on lean, stratified methane-air laminar counterflow flames
Effects of equivalence ratio variation on lean, stratified methane-air laminar counterflow flames
The effects of equivalence ratio variations on flame structure and propagation have been studied computationally. Equivalence ratio stratification is a key technology for advanced low emission combustors. Laminar counterflow simulations of lean methane-air combustion have been presented which show the effect of strain variations on flames stabilized in an equivalence ratio gradient, and the response of flames propagating into a mixture with a time-varying equivalence ratio. “Back supported” lean flames, whose products are closer to stoichiometry than their reactants, display increased propagation velocities and reduced thickness compared with flames where the reactants are richer than the products. The radical concentrations in the vicinity of the flame are modified by the effect of an equivalence ratio gradient on the temperature profile and thermal dissociation. Analysis of steady flames stabilized in an equivalence ratio gradient demonstrates that the radical flux through the flame, and the modified radical concentrations in the reaction zone, contribute to the modified propagation speed and thickness of stratified flames. The modified concentrations of radical species in stratified flames mean that, in general, the reaction rate is not accurately parametrized by
progress variable and equivalence ratio alone. A definition of stratified flame propagation based upon the displacement speed of a mixture fraction dependent progress variable was seen to be suitable for stratified combustion. The response times of the reaction, diffusion, and cross-dissipation components which contribute to this displacement speed have been used to explain flame response to stratification and unsteady fluid dynamic strain.
775-792
Richardson, E.S.
a8357516-e871-40d8-8a53-de7847aa2d08
Granet, V.E.
0976f1c9-9e4c-41d4-a76a-a12477bb6852
Eyssartier, A.
1bc08002-7f25-40ef-9e62-9ec72afe9f3e
Chen, J.H.
fd295f97-acff-4984-a655-ee18d3b2a734
2010
Richardson, E.S.
a8357516-e871-40d8-8a53-de7847aa2d08
Granet, V.E.
0976f1c9-9e4c-41d4-a76a-a12477bb6852
Eyssartier, A.
1bc08002-7f25-40ef-9e62-9ec72afe9f3e
Chen, J.H.
fd295f97-acff-4984-a655-ee18d3b2a734
Richardson, E.S., Granet, V.E., Eyssartier, A. and Chen, J.H.
(2010)
Effects of equivalence ratio variation on lean, stratified methane-air laminar counterflow flames.
Combustion Theory and Modelling, 14 (6), .
Abstract
The effects of equivalence ratio variations on flame structure and propagation have been studied computationally. Equivalence ratio stratification is a key technology for advanced low emission combustors. Laminar counterflow simulations of lean methane-air combustion have been presented which show the effect of strain variations on flames stabilized in an equivalence ratio gradient, and the response of flames propagating into a mixture with a time-varying equivalence ratio. “Back supported” lean flames, whose products are closer to stoichiometry than their reactants, display increased propagation velocities and reduced thickness compared with flames where the reactants are richer than the products. The radical concentrations in the vicinity of the flame are modified by the effect of an equivalence ratio gradient on the temperature profile and thermal dissociation. Analysis of steady flames stabilized in an equivalence ratio gradient demonstrates that the radical flux through the flame, and the modified radical concentrations in the reaction zone, contribute to the modified propagation speed and thickness of stratified flames. The modified concentrations of radical species in stratified flames mean that, in general, the reaction rate is not accurately parametrized by
progress variable and equivalence ratio alone. A definition of stratified flame propagation based upon the displacement speed of a mixture fraction dependent progress variable was seen to be suitable for stratified combustion. The response times of the reaction, diffusion, and cross-dissipation components which contribute to this displacement speed have been used to explain flame response to stratification and unsteady fluid dynamic strain.
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Published date: 2010
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Funded by U.S. Department of Energy: Sandia National Laboratories (DE-AC04-94-AL85000)
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Local EPrints ID: 191099
URI: http://eprints.soton.ac.uk/id/eprint/191099
PURE UUID: fe3982e9-102d-4f5e-9203-7a699cfb278d
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Date deposited: 16 Jun 2011 13:39
Last modified: 15 Mar 2024 03:37
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Author:
V.E. Granet
Author:
A. Eyssartier
Author:
J.H. Chen
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