In order to investigate the effect of the ignition position on deflagration characteristics of premixed methane/air mixture with hydrogen addition

an experimental study was conducted in a transparent pipe with the cross-section of 100 mm×100 mm and the length of 1000 mm with the variation of ignition position (IP) and hydrogen addition ratio (φ). The results indicated that the changing of the flame structures was dependent on both IP and φ when the flames propagated to the vent and the closed end. The formation of the tulip flame was mainly affected by IP when the flame propagated to the vent. Whereas

it was influenced by both IP and φ when the flame propagated to the closed end. The evolution of the flame front could be divided into three categories according to IP and φ. Hydrogen addition had no obvious effects on the flame propagation velocity when φ was less than 0.25. When φ was less than 0.75

the overpressure presented periodic oscillation only under the conditions that the ignition position was in the middle or the rear of the pipe. Moreover

the closer the ignition position was to the vent

the longer the oscillation time would be. With regard to the pure hydrogen explosion

the pressure oscillation disappeared and the arrival time of the maximum peak pressure was basically the same for all ignition positions. The changing trends of the maximum peak pressure with the ignition position were different for various hydrogen addition ratios.