Effects of equivalence ratio variations on turbulent flame speed in lean methane/air mixtures under lean-burn natural gas engine operating conditions

Wang, Zhiyan; Motheau, Emmanuel; Abraham, John

doi:10.1016/j.proci.2016.09.011

Title: Effects of equivalence ratio variations on turbulent flame speed in lean methane/air mixtures under lean-burn natural gas engine operating conditions

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Abstract

Direct numerical simulations of turbulent premixed air flames were carried out using an inflow-outflow configuration to study the effects of equivalence ratio on the turbulent flame speed in lean mixtures. The inflow velocity was dynamically adjusted at a run-time to stabilize the flame brush location within the computational domain. Linear forcing was applied to maintain the turbulent intensities at desired levels. Numerous equivalence ratios near the lean limit were selected for the same turbulence properties and the normalized turbulent flame speed was shown to be a function of the equivalence ratio. Simulations were performed for over 80 eddy turnover times with the turbulent flame speed obtained by averaging the inflow velocity. Results revealed that the equivalence ratio does not have an explicit effect on the normalized turbulent flame speed over the lean limit. Analysis of flame surface area showed that the surface wrinkling produced by eddies of varying scales was not influenced by the change in equivalence ratios when the Karlovitz and Damkohler numbers are fixed. Lastly based on the flame surface statistics flame surface normal is preferentially parallel to the most compressive strain rate direction for all equivalence ratios.

Authors:

^[1];

^[2]; Abraham, John ^[3]

Purdue Univ., West Lafayette, IN (United States). School of Mechanical Engineering
Univ. of Adelaide, SA (Australia). School of Mechanical Engineering
Purdue Univ., West Lafayette, IN (United States). School of Mechanical Engineering; Univ. of Adelaide, SA (Australia). School of Mechanical Engineering; San Diego State Univ., CA (United States). Dept. of Mechanical Engineering

Publication Date:: Thu Oct 13 00:00:00 EDT 2016

Research Org.:: Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)

Sponsoring Org.:: USDOE Office of Science (SC)

OSTI Identifier:: 1525190

Grant/Contract Number:: AC02-05CH11231

Resource Type:: Accepted Manuscript

Journal Name:: Proceedings of the Combustion Institute

Additional Journal Information:: Journal Volume: 36; Journal Issue: 3; Journal ID: ISSN 1540-7489

Publisher:: Elsevier

Country of Publication:: United States

Language:: English

Subject:: 42 ENGINEERING; 03 NATURAL GAS; DNS of turbulent premixed flames; Premixed flame speed; Lean-burn; Natural gas engines

Citation Formats


                    Wang, Zhiyan, Motheau, Emmanuel, and Abraham, John. Effects of equivalence ratio variations on turbulent flame speed in lean methane/air mixtures under lean-burn natural gas engine operating conditions.  United States: N. p., 2016. 
Web.  doi:10.1016/j.proci.2016.09.011.

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                    Wang, Zhiyan, Motheau, Emmanuel, & Abraham, John. Effects of equivalence ratio variations on turbulent flame speed in lean methane/air mixtures under lean-burn natural gas engine operating conditions.  United States.  https://doi.org/10.1016/j.proci.2016.09.011

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                    Wang, Zhiyan, Motheau, Emmanuel, and Abraham, John. Thu .  
"Effects of equivalence ratio variations on turbulent flame speed in lean methane/air mixtures under lean-burn natural gas engine operating conditions".  United States.  https://doi.org/10.1016/j.proci.2016.09.011.  https://www.osti.gov/servlets/purl/1525190.

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@article{osti_1525190,

  title        = {Effects of equivalence ratio variations on turbulent flame speed in lean methane/air mixtures under lean-burn natural gas engine operating conditions},

  author       = {Wang, Zhiyan and Motheau, Emmanuel and Abraham, John},

  abstractNote = {Direct numerical simulations of turbulent premixed air flames were carried out using an inflow-outflow configuration to study the effects of equivalence ratio on the turbulent flame speed in lean mixtures. The inflow velocity was dynamically adjusted at a run-time to stabilize the flame brush location within the computational domain. Linear forcing was applied to maintain the turbulent intensities at desired levels. Numerous equivalence ratios near the lean limit were selected for the same turbulence properties and the normalized turbulent flame speed was shown to be a function of the equivalence ratio. Simulations were performed for over 80 eddy turnover times with the turbulent flame speed obtained by averaging the inflow velocity. Results revealed that the equivalence ratio does not have an explicit effect on the normalized turbulent flame speed over the lean limit. Analysis of flame surface area showed that the surface wrinkling produced by eddies of varying scales was not influenced by the change in equivalence ratios when the Karlovitz and Damkohler numbers are fixed. Lastly based on the flame surface statistics flame surface normal is preferentially parallel to the most compressive strain rate direction for all equivalence ratios.},

  doi          = {10.1016/j.proci.2016.09.011},

  journal      = {Proceedings of the Combustion Institute},

  number       = 3,

  volume       = 36,

  place        = {United States},

  year         = {Thu Oct 13 00:00:00 EDT 2016},

  month        = {Thu Oct 13 00:00:00 EDT 2016}

}

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