A DNS study on the stabilization mechanism of a turbulent lifted ethylene jet flame in highly-heated coflow
A DNS study on the stabilization mechanism of a turbulent lifted ethylene jet flame in highly-heated coflow
Direct numerical simulation (DNS) of the near-field of a three-dimensional spatially-developing turbulent ethylene jet flame in highly-heated coflow is performed with a reduced mechanism to determine the stabilization mechanism. The DNS was performed at a jet Reynolds number of 10,000 with over 1.29 billion grid points. The results show that auto-ignition in a fuel-lean mixture at the flame base is the main source of stabilization of the lifted jet flame. The Damko¨ hler number and chemical explosive mode (CEM) analysis also verify that auto-ignition occurs at the flame base. In addition to auto-ignition, Lagrangian tracking of the flame base reveals the passage of large-scale flow structures and their correlation with the fluctuations of the flame base similar to a previous study (Yoo et al., J. Fluid Mech. 640 (2009) 53–481) with hydrogen/air jet flames. It is also observed that the present lifted flame base exhibits a cyclic ‘saw-tooth’ shaped movement marked by rapid movement upstream and slower movement downstream.
This is a consequence of the lifted flame being stabilized by a balance between consecutive auto-ignition events in hot fuel-lean mixtures and convection induced by the high-speed jet and coflow velocities. This is confirmed by Lagrangian tracking of key variables including the flame-normal velocity, displacement speed, scalar dissipation rate, and mixture fraction at the stabilization point.
direct numerical simulation (dns), auto-ignition, turbulent lifted flame, ethylene, reduced mechanism
1619-1627
Yoo, Chun Sang
75b8ea95-baaa-4961-9d86-214f70e126f7
Richardson, Edward S.
a8357516-e871-40d8-8a53-de7847aa2d08
Sankaran, Ramanan
af2016f7-364d-4ae6-9721-4645b60448f6
Chen, Jacqueline H.
0fae559d-60be-4456-847e-43372476d0e1
2011
Yoo, Chun Sang
75b8ea95-baaa-4961-9d86-214f70e126f7
Richardson, Edward S.
a8357516-e871-40d8-8a53-de7847aa2d08
Sankaran, Ramanan
af2016f7-364d-4ae6-9721-4645b60448f6
Chen, Jacqueline H.
0fae559d-60be-4456-847e-43372476d0e1
Yoo, Chun Sang, Richardson, Edward S., Sankaran, Ramanan and Chen, Jacqueline H.
(2011)
A DNS study on the stabilization mechanism of a turbulent lifted ethylene jet flame in highly-heated coflow.
Proceedings of the Combustion Institute, 33 (1), .
(doi:10.1016/j.proci.2010.06.147).
Abstract
Direct numerical simulation (DNS) of the near-field of a three-dimensional spatially-developing turbulent ethylene jet flame in highly-heated coflow is performed with a reduced mechanism to determine the stabilization mechanism. The DNS was performed at a jet Reynolds number of 10,000 with over 1.29 billion grid points. The results show that auto-ignition in a fuel-lean mixture at the flame base is the main source of stabilization of the lifted jet flame. The Damko¨ hler number and chemical explosive mode (CEM) analysis also verify that auto-ignition occurs at the flame base. In addition to auto-ignition, Lagrangian tracking of the flame base reveals the passage of large-scale flow structures and their correlation with the fluctuations of the flame base similar to a previous study (Yoo et al., J. Fluid Mech. 640 (2009) 53–481) with hydrogen/air jet flames. It is also observed that the present lifted flame base exhibits a cyclic ‘saw-tooth’ shaped movement marked by rapid movement upstream and slower movement downstream.
This is a consequence of the lifted flame being stabilized by a balance between consecutive auto-ignition events in hot fuel-lean mixtures and convection induced by the high-speed jet and coflow velocities. This is confirmed by Lagrangian tracking of key variables including the flame-normal velocity, displacement speed, scalar dissipation rate, and mixture fraction at the stabilization point.
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e-pub ahead of print date: 2 October 2010
Published date: 2011
Keywords:
direct numerical simulation (dns), auto-ignition, turbulent lifted flame, ethylene, reduced mechanism
Organisations:
Engineering Science Unit
Identifiers
Local EPrints ID: 203171
URI: http://eprints.soton.ac.uk/id/eprint/203171
ISSN: 1540-7489
PURE UUID: 093af16a-c910-4c75-9573-759287d53e11
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Date deposited: 14 Nov 2011 11:57
Last modified: 15 Mar 2024 03:37
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Author:
Chun Sang Yoo
Author:
Ramanan Sankaran
Author:
Jacqueline H. Chen
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