Laminar combustion characteristics and mechanism of hydrogen/air mixture diluted with N2Â +Â H2O

•Hydrogen-air laminar combustion speed decrease significantly with N2 + H2O dilution.•Flame instability of hydrogen-air mixture increases slightly with dilution ratio.•Important elementary reactions decrease significantly with N2 + H2O dilution.

Laminar combustion characteristics of hydrogen/air mixture diluted with N2 + H2O are investigated based on experiments in a constant volume combustion bomb. Experiments results show that flame propagating speed and laminar combustion speed decrease significantly with N2 + H2O dilution. Flame stability increases slightly with the increase of dilution rate. It can be revealed that decrease of temperature in reaction zone leads to significant-decrease of all important elementary reactions speed. Concentration increase of dilution gas also slowed down and sometimes even reversed the direction of part of important elementary reaction.