Lifting and Splitting of Nonpremixed Methane/Air Flames Due to Reactant Preheating

In order to assess the impact of initial reactant temperature on the occurrence of local extinction (LE) and the subsequent lifting process of non-premixed attached flames with increasing fuel injection velocity, hydroxyl radical planar laser-induced fluorescence (OH-PLIF) and high-speed CH*-chemilu...

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Bibliographic Details
Published in:Combustion science and technology 2015-12, Vol.187 (12), p.1937-1958
Main Authors: Lamige, Sylvain, Lyons, Kevin M., Galizzi, Cédric, Kühni, Manuel, Mathieu, Éric, Escudié, Dany
Format: Article
Language:English
Subjects:
Extinction
Flame lifting process
Fluorescence
Heating
High speed
Hoisting
Hydroxyl radicals
Local extinction
Mechanics
Methane
Non-premixed flame stabilization
Physics
Preheating
Probability density functions
Split flame
Thermics
Velocity
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Summary:In order to assess the impact of initial reactant temperature on the occurrence of local extinction (LE) and the subsequent lifting process of non-premixed attached flames with increasing fuel injection velocity, hydroxyl radical planar laser-induced fluorescence (OH-PLIF) and high-speed CH*-chemiluminescence visualizations were conducted in a methane/air jet-flame, with preheating up to 1000 K. LE occurrence probability increases when approaching lifting, and the preheating level (T ox,ref ) affects the probability density function (PDF) shape of LE axial origin. At low T ox,ref , partial lifting events occur near the burner lip, eventually leading the flame to lift directly from the very flame base. At higher T ox,ref , partial lifting events no longer occur, and LE is mostly witnessed in the flame breakpoint zone (axially from 1 to 3 jet diameters), resulting in a breakpoint lifting process. For very high T ox,ref (1000 K), local extinctions become widespread in the breakpoint zone so that a stable split flame is achieved prior to the lifted regime.
ISSN:0010-2202
1563-521X
DOI:10.1080/00102202.2015.1059829