FLAME STRUCTURE AND THERMAL NOX FORMATION IN HYDROGEN DIFFUSION FLAMES WITH REDUCED KINETIC MECHANISMS

Structure and thermal NOX formation of hydrogen diffusion flames are s tudied numerically, by adopting a counterflow as a model problem. Deta iled kinetic mechanism having twenty-one step hydrogen oxidation is sy stematically reduced to a two-step mechanism while five-step thermal N OX chemistry of the extended Zel'dovich mechanism is reduced to one-st ep. Results show that the extinction strain rates are much higher than those for hydrocarbon flames and the NOX production can be controlled by increasing strain rates which results in the decrease of flame tem perature significantly. Comparison between the results of the detailed and reduced mechanisms demonstrates that the reduced mechanism succes sfully describes the essential features of hydrogen diffusion flames i ncluding the flame structure, extinction strain rate and NOX productio n.