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Experimental and numerical investigation of premixed flame propagation with distorted tulip shape in a closed duct

Biomedical Sciences Research Institute Computer Science Research Institute Environmental Sciences Research Institute Nanotechnology & Advanced Materials Research Institute

Xiao, Huahua, Makarov, Dmitriy, Sun, Jinhua and Molkov, Vladimir (2012) Experimental and numerical investigation of premixed flame propagation with distorted tulip shape in a closed duct. Combustion and Flame, 159 . pp. 1523-1538. [Journal article]

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DOI: 10.1016/j.combustflame.2011.12.003

Abstract

High-speed schlieren photography, pressure records and large eddy simulation (LES) model are used to study the shape changes, dynamics of premixed flame propagation and pressure build up in a closed duct. The study provides further understanding of the interaction between flame front, pressure wave and combustion-generated flow, especially when the flame acquires a ‘‘distorted tulip’’ shape. The Ulster multi-phenomena LES premixed combustion model is applied to gain an insight into the phenomenon of ‘‘distorted tulip’’ flame and explain the experimental observations. The model accounts for the effects of flow turbulence, turbulence generated by flame front itself, selective diffusion, and transient pressure and temperature on the turbulent burning velocity. The schlieren images show that the flame exhibits a salient ‘‘distorted tulip’’ shape with two secondary cusps superimposed onto the two original tulip lips. This curious flame shape appears after a well-pronounced classical tulip flame is formed. The dynamics of ‘‘distorted tulip’’ flame observed in the experiment is well reproduced by LES. The numerical simulations show that large-scale vortices are generated in the burnt gas after the formation of a classical tulip flame. The vortices remain in the proximity of the flame front and modify the flow field around the flame front. As a result, the flame front in the original cusp and near the sidewalls propagates faster than that close to the centre of the original tulip lips. The discrepancy in the flame propagation rate finally leads to the formation of the ‘‘distorted tulip’’ flame. The LES model validated previously against large-scale hydrogen/air deflagrations is successfully applied in this study to reproduce the dynamics of flame propagation and pressure build up in the small-scale duct. It is confirmed that grid resolution has an influence to a certain extent on the simulated combustion dynamics after the flame inversion.

Item Type:Journal article
Faculties and Schools:Faculty of Art, Design and the Built Environment
Faculty of Art, Design and the Built Environment > School of the Built Environment
Research Institutes and Groups:Built Environment Research Institute
Built Environment Research Institute > Hydrogen Safety Engineering and Research Centre (HySAFER)
ID Code:22710
Deposited By:Professor Vladimir Molkov
Deposited On:28 Jun 2012 12:32
Last Modified:07 Apr 2014 10:10

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