Experimental study of premixed turbulent combustion in opposed streams. Part II—Reacting flow field and extinction

Turbulent combustion in opposed streams of premixed reactants was studied experimentally. In this geometry two flames are stabilized in the vicinity of the free stagnation point and separated by a region of products. In the mean the flames appear flat and perpendicular to the axis of the jets. Both...

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Bibliographic Details
Published in:Combustion and flame 1993-03, Vol.92 (4), p.396-409
Main Authors: Kostiuk, L.W., Bray, K.N.C., Cheng, R.K.
Format: Article
Language:English
Subjects:
400800 - Combustion, Pyrolysis, & High-Temperature Chemistry
AIR
ALKANES
COMBUSTION PRODUCTS
DISPERSIONS
FLAMES
FLUID FLOW
FLUID MECHANICS
FLUIDS
GASES
HYDROCARBONS
INHIBITION
INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY
MATHEMATICAL MODELS
MECHANICS
MIXING
MIXTURES
ORGANIC COMPOUNDS
PROPANE
STABILIZATION
STAGNATION POINT
TURBULENT FLOW
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Summary:Turbulent combustion in opposed streams of premixed reactants was studied experimentally. In this geometry two flames are stabilized in the vicinity of the free stagnation point and separated by a region of products. In the mean the flames appear flat and perpendicular to the axis of the jets. Both the mean flow field and the distribution of the mean progress variable is found to be symmetric about the stagnation point. Buoyancy forces do not appear to affect the symmetry of the flow. The flows upstream of the flame zones has the same form of velocity field as nonreacting opposed flow, but displaced away from the stagnation point by the volume source due to combustion. Under certain conditions these flames can be forced to extinction, and this limit is studied for lean propane-air mixtures. This extinction depends only on the aerothermochemistry of the flow because there are no surfaces near the flames. For near extinct flames the flow field approaches that of nonreacting opposed streams. A physical mechanism is proposed for the extinction and results are compared with an extinction model. There is good qualitative agreement with the extinction model, and good quantitative agreement for the dependency of unstretched laminar burning velocity and the heat release parameter on extinction.
ISSN:0010-2180
1556-2921
DOI:10.1016/0010-2180(93)90151-R