Characteristics of annular lean flame and effects of the injection of air co-flow
Date Issued
2010
Date
2010
Author(s)
Lin, Hung-Wei
Abstract
The characteristics of annular lean methane flames with different equivalence ratios(φmid=0.5–0.95) and outlet flow velocities(Umid=0.5–4.0 m/s), and the effects of the injection of air co-flow are experimentally studied in a bluff-body multi-ring burner by flame image, flow path line, high speed PIV(1000, 2000 fps) and temperature mea-surement.
Result shows that annular lean flames can be classified into four modes: cone flame, half-cone flame, lift-off flame, and extinguishment. Combustion is strong and efficient at cone flame mode, and then gets weaker through half-cone flame, lift-off flame and finally to extinguishment. In order to enhance chemical reaction in weak combustion mode such as half-cone flame mode, there is no need to add extra materials or fuel, just injecting air co-flow with velocity ratio Uout /Umid > 0.3-0.7(depending on reactant flow velocity Umid) around the outer side of annular lean flame can promote chemical reaction and make the flame transfer into a more stabilized mode – tulip flame.
Subjects
Lean combustion
Annular flame
Bluff-body stabilization
Air co-flow
Flame holding
Type
thesis
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