Quantification of transient stretch effects on kernel-vortex interactions in premixed methane-air flames

Journal Article · Tue Jul 15 04:00:00 EDT 2008 · Combustion and Flame

DOI:https://doi.org/10.1016/J.COMBUSTFLAME.2008.02.003· OSTI ID:21044888

Marley, S K; Danby, S J; Roberts, W L ^[1]; Drake, M C; Fansler, T D ^[2]

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1. Department of Mechanical and Aerospace Engineering, North Carolina State University, Campus Box 7910, Raleigh, NC 27695 (United States)
2. General Motors Research and Development, Warren, MI 48090 (United States)

Relative flame speeds of time-dependent highly curved premixed methane-air flames (spark-ignited flame kernels) interacting with a laminar vortex have been quantified using high-speed chemiluminescence imaging, particle image velocimetry, and piezoelectric pressure measurements. The goals of this study are to improve fundamental understanding of transient stretch effects on highly curved premixed flames, to provide practical insight into the turbulent growth of spark-ignited flame kernels in internal combustion (IC) engines burning light hydrocarbon fuels, and to provide data for IC engine ignition and combustion model development. Lean and rich CH{sub 4}-O{sub 2}-N{sub 2} flames were tested ({phi}=0.64, 0.90, and 1.13, with nitrogen dilution to equalize the flame speeds (S{sub b}) in the absence of vortex interaction). Transient stretch rates were varied using three different vortex strengths, and the size of the flame kernel at the start of the vortex interaction controlled by time delay between ignition and vortex generation. Vortex interactions with small ({proportional_to}5 mm radius) flame kernels were found to increase burning rates for lean ({phi}=0.64) flame kernels substantially. Burning rates for rich ({phi}=1.13) flames were decreased, with total flame kernel extinction occurring in extreme cases. These small flame kernel-vortex interactions are dominated by transient stretch effects and thermodiffusive stability, in agreement with premixed flame theory. However, vortex interactions with larger methane-air flame kernels ({proportional_to}30 mm radius) led to slight flame speed enhancements for both lean and rich flame kernels, with the flame-vortex process dominated by increased flamefront area generated by vortex-induced flame wrinkling. (author)

• OSTI ID: 21044888
• Journal Information: Combustion and Flame, Journal Name: Combustion and Flame Journal Issue: 1-2 Vol. 154; ISSN CBFMAO; ISSN 0010-2180
• Country of Publication: United States
• Language: English

Related Subjects

33 ADVANCED PROPULSION SYSTEMS
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
AIR
AUGMENTATION
COMBUSTION
COMBUSTION KINETICS
FLAME PROPAGATION
FLAMES
HYDROCARBONS
IGNITION
INTERNAL COMBUSTION ENGINES
METHANE
NITROGEN
OXYGEN
STABILITY
TIME DELAY
TIME DEPENDENCE
TRANSIENTS
VELOCITY
VORTICES