A numerical study of lean CH4/H-2/air premixed flames at high pressure

We perform a numerical study of the effect of including a small amount of h ydrogen in lean methane-air premixed flames at high pressure and high tempe rature conditions. It has been shown recently (Bell and Gupta (1997)) that hydrogen addition extends the lean operating limit of natural gas engines, leading to a potential decrease in pollutant formation. We suggest here tha t the origin of this effect is that, at constant global equivalence ratio, the stretch resistance of these flames is considerably increased by hydroge n blending, while other dame properties, such as ignition time and burnt ga s temperature, are comparatively little modified.