Reaction chemistry, flame propagation

Figures 12.3 and 12.3c show mean velocity (Fig. 12.36) and mean temperature (Fig. 12.3c) fields under bluff-body stabilized combustion of stoichiometric methane-air mixture at inlet velocity 10 m/s, and ABC of Eq. (12.19) at the combustor outlet. Functions Wj, Wij, and W2j in Eq. (12.1) were obtained by solving the problem of laminar flame propagation with the detailed reaction mechanism [31] of Ci-C2-hydrocarbon oxidation (35 species, 280 reactions) including CH4 oxidation chemistry. The PDF of Eq. (12.4) was used in this calculation.

What problems face the theory of combustion The theory of combustion must be transformed into a chapter of physical chemistry. Basic questions must be answered will a compound of a given composition be combustible, what will be the rate of combustion of an explosive mixture, what peculiarities and shapes of flames should we expect We shall not be satisfied with an answer based on analogy with other known cases of combustion. The phenomena must be reduced to their original causes. Such original causes for combustion are chemical reaction, heat transfer, transport of matter by diffusion, and gas motion. A direct calculation of flame velocity using data on elementary chemical reaction events and thermal constants was first carried out for the reaction of hydrogen with bromine in 1942. The problem of the possibility of combustion (the concentration limit) was reduced for the first time to thermal calculations for mixtures of carbon monoxide with air. Peculiar forms of propagation near boundaries which arise when normal combustion is precluded or unstable were explained in terms of the physical characteristics of mixtures. 

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