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Author

Yoo, Chun Sang
Combustion & Propulsion Lab
Research Interests
  • Numerical turbulent combustion

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A DNS study on the stabilization mechanism of a turbulent lifted ethylene jet flame in highly-heated coflow

Cited 34 times inthomson ciCited 31 times inthomson ci
Title
A DNS study on the stabilization mechanism of a turbulent lifted ethylene jet flame in highly-heated coflow
Author
Yoo, Chun SangRichardson, Edward S.Sankaran, RamananChen, Jacqueline H.
Keywords
Auto-ignition; Chemical explosive; Co-flow; Direct numerical simulation (DNS); Displacement speed; Grid points; High-speed jet; Jet flames; Key variables; Lagrangian tracking; Large-scale flow structure; Lean mixtures; Lifted flames; Mixture fraction; Near-field; Rapid movements; Reduced mechanisms; Saw-tooth; Scalar dissipation rate; Stabilization mechanisms
Issue Date
201101
Publisher
ELSEVIER SCIENCE INC
Citation
PROCEEDINGS OF THE COMBUSTION INSTITUTE, v.33, no.1, pp.1619 - 1627
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 Damkohler 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) 453-481) 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.
URI
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DOI
http://dx.doi.org/10.1016/j.proci.2010.06.147
ISSN
1540-7489
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MNE_Journal Papers

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