Nnumerical Study of the Effects of Pressure and Air-Dilution on NO Formation in Laminar Counterflow Diffusion Flames of Methane in High Temperature Air

摘要

Flame structure, extinction characteristics, and nitric oxide (NO) formation in diffusion flames of methane and diluted air have been investigated numerically by adopting counterflow as a model. Effect of pressure on NO emission is emphasized in high-temperature and diluted-air conditions. With undiluted air, extinction strain rate and flame temperature at a specified strain rate increase with pressure. In this case, thermal NO is dominant over prompt NO and pressure rise enhances chain branching/recombination reactions and increases flame temperature and mole fractions of H, O, and OH.