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A numerical study of diffusive effects in turbulent lean premixed hydrogen flames

A numerical study of diffusive effects in turbulent lean premixed hydrogen flames
A numerical study of diffusive effects in turbulent lean premixed hydrogen flames
Three-dimensional direct numerical simulation of lean premixed hydrogen flames is used to explore the influence of species and thermal diffusion and viscosity on the flame structure and turbulent flame response. The leading-order flame response is shown to be due to the global Lewis number with little influence from the other species. The previously-reported observation of decorrelation of fuel consumption and heat release at high Karlovitz numbers is shown to be solely due to atomic hydrogen diffusion. Finally, it is shown that the suppression of turbulence through the flame cannot be attributed to an increase in viscosity due to the increase in temperature, but that the effect is not negligible. It is further argued that turbulence–flame interactions are better described considering Kolmogorov’s second similarity hypothesis (rather than the first); specifically, by a Karlovitz number that is defined based on the inertial subrange (i.e. the energy dissipation rate) rather than the dissipation subrange (i.e. viscosity or equivalently Kolmogorov scale quantities).
1540-7489
1997-2004
Aspden, A.J.
7353e0e9-fbed-4f5a-a610-b045cd4cd576
Aspden, A.J.
7353e0e9-fbed-4f5a-a610-b045cd4cd576

Aspden, A.J. (2016) A numerical study of diffusive effects in turbulent lean premixed hydrogen flames. Proceedings of the Combustion Institute, 36 (2), 1997-2004. (doi:10.1016/j.proci.2016.07.053).

Record type: Article

Abstract

Three-dimensional direct numerical simulation of lean premixed hydrogen flames is used to explore the influence of species and thermal diffusion and viscosity on the flame structure and turbulent flame response. The leading-order flame response is shown to be due to the global Lewis number with little influence from the other species. The previously-reported observation of decorrelation of fuel consumption and heat release at high Karlovitz numbers is shown to be solely due to atomic hydrogen diffusion. Finally, it is shown that the suppression of turbulence through the flame cannot be attributed to an increase in viscosity due to the increase in temperature, but that the effect is not negligible. It is further argued that turbulence–flame interactions are better described considering Kolmogorov’s second similarity hypothesis (rather than the first); specifically, by a Karlovitz number that is defined based on the inertial subrange (i.e. the energy dissipation rate) rather than the dissipation subrange (i.e. viscosity or equivalently Kolmogorov scale quantities).

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Accepted/In Press date: 15 July 2016
e-pub ahead of print date: 13 October 2016
Published date: 2016
Organisations: Applied Mathematics

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Local EPrints ID: 396283
URI: https://eprints.soton.ac.uk/id/eprint/396283
ISSN: 1540-7489
PURE UUID: 15c1137f-6138-4163-96b5-b943c9059887

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Date deposited: 07 Jun 2016 14:01
Last modified: 17 May 2018 16:31

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Author: A.J. Aspden

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