Abstract: In order to further develop explosion-proof technology and equipment for underground gas explosion accidents in coal mines, gas deflagration propagation experiment was carried out when there were no obstacles and when there were spherical obstacles by using a square pipe with a cross section of 0.2 m×0.2 m, schlieren device and high-speed camera. Study shows that when there are no obstacles, structure and propagation speed of deflagration flame in a sealed pipeline are greatly affected by reflected pressure wave. Mutual game between turbulent flame, chemical reaction ability, and reflected pressure wave is main reason for change of flame propagation speed. When a spherical obstacle exists, flame is disturbed and stretched into a front, a center and a tail, and front is the fastest, tail is the slowest. Flame front has an overall acceleration trend from passing obstacle. Compared with obstacle, time to pass observation period is significantly shorter.

Key words: spherical obstacles, gas deflagration, airtight pipeline, flame propagation, reflected pressure wave