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Computed Structure of Low Strain Rate Partially Premixed CH4/Air Counterflow Flames: Implications for NO Formation.


pdf icon Computed Structure of Low Strain Rate Partially Premixed CH4/Air Counterflow Flames: Implications for NO Formation. (2242 K)
Blevins, L. G.; Gore, J. P.

Combustion and Flame, Vol. 116, 546-566, 1999.

Sponsor:

Naval Research Lab., Washington, DC

Keywords:

combustion chemistry; computation; counterflow flames; flame structure; nitrogen oxides; pollution; simulation

Abstract:

Results from computations of low strain rate, partially premixed methane/air counterflow flames are reported. The Oppdif computer code was used with GRI-Mech 2.11 to obtain the results. When the fuel-side equivalence ratio is above 2.5, the present flame structure can be described as a CH4/air premixed flame merged with a CO/H2/air nonpremixed flame. When the equivalence ratio is below 2.5, the two flame zones exist on the opposite sides of the stagnation plane, and the CO/H2/air nonpremixed flame is characterized by hydrocarbon concentration peaks on its fuel-side edge. Broad NO destruction regions, caused by CHi+NO reactions, exist between the result in double hydrocarbon concentration peaks. The fuel-side equivalence ratio is the most important indicator of how rapidly NO is destroyed relative to how rapidly it is formed, and NO destruction reactions are more important inpure diffusion flames than in partially premixed flames for the present low strain rate computations.