A theoretical analysis of the extinction limits of a methane-air opposed-jet diffusion flame
A theoretical analysis is described for a methane-air diffusion flame stabilized in the forward stagnation region of a porous metal cylinder in a forced convective flow. The analysis includes effects of radiative heat loss from the porous metal surface and finite rate kinetics but neglects the effects of gravity. The theoretically predicted extinction limits compare well with experimentally observed extinction limits from the literature. After the predicted limits compared well with the experimental limits, a parametric study of the effect of fuel surface emissivity and Lewis number was conducted with the numerical model. It was found that the computed blowoff limit is independent of radiative heat loss for high fuel blowing velocities but is a strong function of Lewis number. At low fuel blowing velocities, the extinction limit varies with both radiative heat loss and Lewis number. It is discovered, however, that even if thermal losses from the fuel surface are absent, the flame can extinguish at the fuel surface independently of Lewis number due to excessive reaction zone thinning.
- Research Organization:
- NASA-Lewis Research Center, Cleveland, OH 44135
- OSTI ID:
- 5940571
- Journal Information:
- Combust. Flame; (United States), Journal Name: Combust. Flame; (United States) Vol. 70:2; ISSN CBFMA
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
400800* -- Combustion
Pyrolysis
& High-Temperature Chemistry
AIR
ALKANES
CHEMICAL REACTION KINETICS
COMBUSTION KINETICS
CONVECTION
CYLINDERS
DIFFUSION
ELEMENTS
ENERGY LOSSES
ENERGY TRANSFER
FLAME PROPAGATION
FLAMES
FLUIDS
FORCED CONVECTION
FUELS
GASES
HEAT LOSSES
HEAT TRANSFER
HYDROCARBONS
JETS
KINETICS
LOSSES
MASS TRANSFER
METALS
METHANE
ORGANIC COMPOUNDS
REACTION KINETICS
THERMAL DIFFUSION
THERMODYNAMICS