Analysis of turbulent flame propagation in equivalence ratio-stratified flow
Analysis of turbulent flame propagation in equivalence ratio-stratified flow
Equivalence ratio-stratified combustion is an important technology for achieving stable low-emission operation in internal combustion engines and gas turbines. This study examines how equivalence ratio stratification affects the physics of turbulent flame propagation using Direct Numerical Simulation. Three-dimensional simulations of a turbulent slot-Bunsen flame configuration are performed with accurate multi-step kinetic modelling for methane-air combustion. We compare one perfectly-premixed and three equivalence ratio-stratified cases with the mean equivalence ratio gradient aligned with, tangential to or opposed to the mean flame brush. The simulation results are analysed in terms of flame surface area and the burning intensity. The local effects of stratification are then investigated further by examining statistics of the displacement speed conditioned on the flame-normal equivalence ratio gradient. The local burning intensity is found to depend on the orientation of the stratification with respect to the flame front, so that burning intensity is enhanced when the flame speed in the products is faster than in the reactants. This effect of alignment between equivalence ratio gradients and flame fronts has been observed previously in laminar flames and it is found here that it also affects the global behaviour of turbulent flames. The flame surface area is also influenced by equivalence ratio stratification and this may be explained by differences in the surface-averaged consumption speed and differential propagation effects due to flame speed variations associated with equivalence ratio fluctuations.
stratified, partially-premixed, direct numerical simulation, displacement speed, flame surface density
1729-1736
Richardson, E.S.
a8357516-e871-40d8-8a53-de7847aa2d08
Chen, J.H.
fd295f97-acff-4984-a655-ee18d3b2a734
9 February 2017
Richardson, E.S.
a8357516-e871-40d8-8a53-de7847aa2d08
Chen, J.H.
fd295f97-acff-4984-a655-ee18d3b2a734
Richardson, E.S. and Chen, J.H.
(2017)
Analysis of turbulent flame propagation in equivalence ratio-stratified flow.
Proceedings of the Combustion Institute, 36 (2), .
(doi:10.1016/j.proci.2016.06.140).
Abstract
Equivalence ratio-stratified combustion is an important technology for achieving stable low-emission operation in internal combustion engines and gas turbines. This study examines how equivalence ratio stratification affects the physics of turbulent flame propagation using Direct Numerical Simulation. Three-dimensional simulations of a turbulent slot-Bunsen flame configuration are performed with accurate multi-step kinetic modelling for methane-air combustion. We compare one perfectly-premixed and three equivalence ratio-stratified cases with the mean equivalence ratio gradient aligned with, tangential to or opposed to the mean flame brush. The simulation results are analysed in terms of flame surface area and the burning intensity. The local effects of stratification are then investigated further by examining statistics of the displacement speed conditioned on the flame-normal equivalence ratio gradient. The local burning intensity is found to depend on the orientation of the stratification with respect to the flame front, so that burning intensity is enhanced when the flame speed in the products is faster than in the reactants. This effect of alignment between equivalence ratio gradients and flame fronts has been observed previously in laminar flames and it is found here that it also affects the global behaviour of turbulent flames. The flame surface area is also influenced by equivalence ratio stratification and this may be explained by differences in the surface-averaged consumption speed and differential propagation effects due to flame speed variations associated with equivalence ratio fluctuations.
Text
Stratified_PROCI_eprints_2015.pdf
- Author's Original
More information
Submitted date: 3 December 2015
Accepted/In Press date: 20 June 2016
e-pub ahead of print date: 31 October 2016
Published date: 9 February 2017
Venue - Dates:
7th European Combustion Meeting (ECM2015), Budapest, Hungary, 2015-03-30 - 2015-04-02
Keywords:
stratified, partially-premixed, direct numerical simulation, displacement speed, flame surface density
Organisations:
Aerodynamics & Flight Mechanics Group
Identifiers
Local EPrints ID: 384837
URI: http://eprints.soton.ac.uk/id/eprint/384837
ISSN: 1540-7489
PURE UUID: ba321d97-dd65-4331-be14-e054bc7f5e66
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Date deposited: 11 Jan 2016 12:21
Last modified: 15 Mar 2024 03:37
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Author:
J.H. Chen
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