The effects of the Lewis number of the fuel on the displacement speed of edge flames in igniting turbulent mixing layers

Hesse, H. , Chakraborty, N. and Mastorakos, E. (2009) The effects of the Lewis number of the fuel on the displacement speed of edge flames in igniting turbulent mixing layers. Proceedings of the Combustion Institute, 32(1), pp. 1399-1407. (doi:10.1016/j.proci.2008.06.065)

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Abstract

The effects of the Lewis number of the fuel LeF on the statistics of the density weighted displacement speed of edge flames originating from localised ignition of turbulent fuel-air mixing layers under decaying turbulence are studied using 3D direct numerical simulations (DNS) with simplified chemistry for Le = 0.8, 1.0 and 1.2. The edge flame propagation is analysed in terms of the reaction, normal diffusion and tangential diffusion components of Sd . The variations of Sd in response to mixture fraction gradient and curvature are found to be non-linear and consistent with previous DNS with detailed chemistry and experimental studies with laminar flames. It is shown that LeF significantly affects the strength of these correlations and the probability of finding negative Sd decreases, while the mean value of Sd increases, with decreasing LeF. The fuel consumption rate is highest (lowest) in the LeF = 0.8 (LeF = 1.2) flame. This in turn affects the statistics principally through the reaction component of Sd. The results imply that care is needed when extrapolating knowledge from gaseous fuel edge flame studies done with methane to liquid hydrocarbon fuels or hydrogen enriched fuels.

Item Type:Articles
Keywords:Curvature, displacement speed, Lewis number, mixture fraction gradient, turbulent edge flame.
Status:Published
Refereed:Yes
Glasgow Author(s) Enlighten ID:Hesse, Dr Henrik
Authors: Hesse, H., Chakraborty, N., and Mastorakos, E.
College/School:College of Science and Engineering > School of Engineering > Aerospace Sciences
Journal Name:Proceedings of the Combustion Institute
Publisher:Elsevier
ISSN:1540-7489
ISSN (Online):1873-2704
Published Online:14 September 2008

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