Fuel effects on flame lift-off under diesel conditions

Journal Article · Sat Jan 15 04:00:00 EST 2011 · Combustion and Flame

DOI:https://doi.org/10.1016/J.COMBUSTFLAME.2010.07.020· OSTI ID:21396161

Persson, Helena; Andersson, Oeivind; Egnell, Rolf ^[1]

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1. Lund University (Sweden). Dept. of Energy Sciences

An apparent relation between the lift-off length under diesel conditions and the ignition quality of a fuel has previously been reported. To cast light on the underlying mechanism, the current study aims to separate flame lift-off effects of the chemical ignition delay from those of other fuel properties under diesel conditions. Flame lift-off was measured in an optical diesel engine by high-speed video imaging of OH-chemiluminescence. Fuel and ambient-gas properties were varied during the experiment. Only a weak correlation was found between ignition delay and lift-off length. The data indicate that this correlation is due to a common, stronger correlation with the ambient oxygen concentration. The chemical ignition delay and the fuel type had similar, weak effects on the lift-off length. A recently proposed mechanism for lift-off stabilization was used to interpret the results. It assumes that reactants approaching the lift-off position of the jet are mixed with high-temperature products found along the edges of the flame, which trigger autoignition. In this picture, the fuel effect is most likely due to differences in the amount of mixing with high-temperature products that is required for autoignition. In the current experiment, all lift-off effects seem to arise from variations in the reactant and product temperatures, induced by fuel and ambient properties. (author)

• OSTI ID: 21396161
• Journal Information: Combustion and Flame, Journal Name: Combustion and Flame Journal Issue: 1 Vol. 158; 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
ANTIKNOCK RATINGS
AUTOIGNITION
CHEMILUMINESCENCE
COMBUSTION KINETICS
CORRELATIONS
DIESEL ENGINES
Diesel combustion
FLAMES
FUELS
IGNITION QUALITY
Ignition enhancers
JETS
LENGTH
Lift-off length
MIXING
OXYGEN
STABILIZATION
TEMPERATURE RANGE 0273-0400 K
TIME DELAY
VARIATIONS