Effects of hydrogen addition on propagation characteristics of premixed methane/air flames

• Effects of hydrogen addition on methane/air premixed flame propagation characteristics were experimentally studied.
• Hydrogen addition can significantly influence the flame front structure.
• There is a close relationship between the maximum overpressure and the laminar flame speed.

An experimental study has been conducted to investigate the effects of hydrogen addition on the fundamental propagation characteristics of methane/air premixed flames at different equivalence ratios in a venting duct. The hydrogen fraction in the methane–hydrogen mixture was varied from 0 to 1 at equivalence ratios of 0.8, 1.0 and 1.2. The results indicate that the tendency towards flame instability increased with the fraction of hydrogen, and the premixed hydrogen/methane flame underwent a complex shape change with the increasing hydrogen fraction. The tulip flame only formed when the fraction of hydrogen ranged from 0 to 50% at an equivalence ratio of 0.8. It was also found that the flame front speed and the overpressure increased significantly with the hydrogen fraction. For all equivalence ratios, the stoichiometric flame (Φ = 1.0) has the shortest time of flame propagation and the maximum overpressure.