The propagation of a laminar reaction front during end-gas auto-ignition

Jason B. Martz*, George A. Lavoie, Hong G. Im, Robert J. Middleton, Aristotelis Babajimopoulos, Dionissios N. Assanis

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

58 Scopus citations

Abstract

A transient, one dimensional premixed laminar reaction front is used as a model problem to further understand the physical processes influencing reaction front propagation during the various stages of spark-assisted compression ignition (SACI) combustion for both constant and variable domain pressures. This approach is consistent with the wrinkled laminar flame representation of turbulent, spark ignited engine combustion. With the proper choice of timescales and pressure rise rate, it applies to the interaction of the flame with auto-igniting end-gas in a typical automotive engine. Under the conditions simulated by a transient flame code, the reaction front begins as a deflagration, propagating into an end-gas with an initially negligible level of reaction progress. The diffusive-reactive nature of the front is maintained until significant levels of end-gas reaction progress, where the burning velocity depends upon the degree of pre-reaction. At the time of the end-gas maximum chemical power, the maximum temperature gradient and peak rate of heat conduction within the front diminish to the point where combustion becomes chemically controlled. Although significant increases in burning velocity are observed at the onset of chemically controlled combustion within the front, the end-gas is within one front time from the completion of combustion. As a result, no more than one front thickness is consumed by the apparent propagation of the spontaneous ignition front.

Original languageEnglish (US)
Pages (from-to)2077-2086
Number of pages10
JournalCombustion and Flame
Volume159
Issue number6
DOIs
StatePublished - Jun 2012
Externally publishedYes

Bibliographical note

Funding Information:
This work was sponsored by the Department of Energy under the University Consortium on Low Temperature Combustion for High Efficiency, Ultra-Low Emission Engines, directed by the University of Michigan under agreement DE-FC26-06NT42629. The authors gratefully acknowledge Professor J.Y. Chen of University of California, Berkeley for providing the skeletal isooctane mechanism, and Drs. William Pitz and Charles Westbrook of The Lawrence Livermore National Laboratory for the provision of HCT and discussions on the topic. The authors also wish to thank Dr. David Reuss of the University of Michigan for the many helpful discussions.

Keywords

  • Auto-ignition
  • Knock
  • Laminar burning velocity
  • Low temperature combustion
  • Spark assisted compression ignition
  • Spark ignition

ASJC Scopus subject areas

  • General Chemistry
  • General Chemical Engineering
  • Fuel Technology
  • Energy Engineering and Power Technology
  • General Physics and Astronomy

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