The interplay of transport, kinetics, and thermal interactions in the stability of premixed hydrogen/air flames near surfaces
- Univ. of Massachusetts, Amherst, MA (United States). Dept. of Chemical Engineering
The stability of premixed hydrogen/air flames near surfaces is studied using numerical bifurcation theory and detailed kinetics. Two-parameter continuation diagrams are constructed to determine the effects of inlet composition and pressure on flame stability. Sensitivity analysis is used to elucidate the roles of transport mechanisms, chemical heat, and chain-branching in ignition and extinction. The authors have found that flame instabilities can be caused by chemical autocatalysis (kinetic runaway) or thermal autocatalysis (thermal runaway) when three multiple solutions coexist, and by both mechanisms when five multiple solutions coexist. Low pressures favor the kinetic feedback mechanism and high pressures the thermal one. Loss of H atoms out of ht reaction zone by diffusion and convection of H{sub 2}O{sub 2} affects flame stability at high pressures. Energy conduction and convection can influence ignition and extinction, especially at low pressures. At high pressures flame instabilities are mainly driven by reaction heat generation and are strongly affected by transport effects and the enhanced third body efficiency of H{sub 2}O in the reaction H + O{sub 2} + M {yields} HO{sub 2} + M.
- OSTI ID:
- 116458
- Journal Information:
- Combustion and Flame, Journal Name: Combustion and Flame Journal Issue: 1-2 Vol. 103; ISSN CBFMAO; ISSN 0010-2180
- Country of Publication:
- United States
- Language:
- English
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