The asymptotic structure of nonpremixed methane-air flames with oxidizer leakage of order unity
- Univ. of California, San Diego, La Jolla, CA (United States)
The asymptotic structure of nonpremixed methane-air flames is analyzed using a reduced three-step mechanism. The three global steps of this reduced mechanism are similar to those used in a previous analysis. The rates of the three steps are related to the rates of the elementary reactions appearing in the C{sub 1}-mechanism for oxidation of methane. The present asymptotic analysis differs from the previous analysis in that oxygen is presumed to leak from the reaction zone to the leading order. Chemical reactions are presumed to occur in three asymptotically thin layers: the fuel-consumption layer, the nonequilibrium layer for the water-gas shift reaction and the oxidation layer. The structure of the fuel-consumption layer is presumed to be identical to that analyzed previously and in this layer the fuel reacts with the radicals to form primarily CO and H{sub 2} and some CO{sub 2} and H{sub 2}O In the oxidation layer the CO and H{sub 2} formed in the fuel-consumption layer are oxidized to CO{sub 2} and H{sub 2}O. The present analysis of the oxidation layer is simpler than the previous analysis because the variation in the values of the concentration of oxygen can be neglected to the leading order and this is a better representation of the flame structure in the vicinity of the critical conditions of extinction. The predictions of the critical conditions of extinction of the present model are compared with the predictions of previous models. It is anticipated that the present simple model can be easily extended to more complex problems such as pollutant formation in flames or chemical inhibition of flames.
- OSTI ID:
- 63251
- Journal Information:
- Combustion and Flame, Journal Name: Combustion and Flame Journal Issue: 1-2 Vol. 101; ISSN 0010-2180; ISSN CBFMAO
- Country of Publication:
- United States
- Language:
- English
Similar Records
Rate-ratio asymptotic analysis of inhibition of nonpremixed methane-air flames by CF{sub 3}Br
The asymptotic structure of premixed methane-air flames with slow CO oxidation