Abstract: In this paper, the effect of discontinuous distribution of premixed gas on methane/air explosion was studied experimentally in a rectangular closed pipe with a length of 900 mm and a section of 100 mm×100 mm. Segmentally introduce methane/air with a volume fraction of 9.5% into the pipe to form two types of discontinuous distribution premixed gases: methane/air-air and methane/air-air-methane/air. The results show that the flame propagation distance, flame tip speed and explosion overpressure increase with the shortening of the air area. Especially in the form of methane/air-air-methane/air distribution, when the intermediate air area is less than 500 mm, the flame will pass through and cause a secondary explosion, and its overpressure will increase with the decrease of the air area. The research results can provide theoretical support for the prevention and control of natural gas explosion accidents.

Key words: discontinuous distribution, methane/air, flame behavior, flame tip speed, explosive overpressure