The structure and stability of the laminar counter-flow partially premixed methane/air triple flame

This paper reports on a laser diagnostic study involving LDV, OH PLIF, and Rayleigh scattering of the flame structure of counterflowing, partially premixed methane-air flames with counterflowing triple flames (TFs) or as thick double flames. Qualitative OH concentration profiles along the symmetry a...

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Bibliographic Details
Published in:Combustion and flame 1999-10, Vol.119 (1-2), p.109-120
Main Authors: LOCKETT, R. D, BOULANGER, B, HARDING, S. C, GREENHALGH, D. A
Format: Article
Language:English
Subjects:
03 NATURAL GAS
Applied sciences
COMBUSTION KINETICS
Combustion of gaseous fuels
Combustion. Flame
Energy
Energy. Thermal use of fuels
Exact sciences and technology
FLAMES
INHIBITION
LAMINAR FLOW
METHANE
MORPHOLOGY
STABILITY
Theoretical studies. Data and constants. Metering
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Summary:This paper reports on a laser diagnostic study involving LDV, OH PLIF, and Rayleigh scattering of the flame structure of counterflowing, partially premixed methane-air flames with counterflowing triple flames (TFs) or as thick double flames. Qualitative OH concentration profiles along the symmetry axis of an axially symmetric laminar counterflowing methane-air partially premixed TFs show three principal oxidation regions as local peaks in OH concentration. Premixed and diffusion flame (DF) merging limits are determined as a function of mean axial flow strain rate, along with the conditions for the existence of the DF. The conditions define the stability map for the laminar counterflowing methane-air TF. It is proven possible to construct a 2D TF stability map with equivalence ratio plotted against global strain rate. Three TF conditions are measured in detail, including measurements of OH concentration profiles and Rayleigh scattering profiles. 1D LDV measurements of the radial and axial velocity profiles are obtained for two of the three TF conditions. The counterflow TF is significantly more sensitive to rich flame stoichiometry than to the lean flame stoichiometry, and it is also sensitive to axial strain. The axial strain rate at diffusion flame extinction is measured to be 710/s using 1D LDV. (AIAA)
ISSN:0010-2180
1556-2921
DOI:10.1016/s0010-2180(99)00046-2