Abstract: In order to reveal the suppression effect of water mist on deflagration and the influence of the release position of water mist on the deflagration process of methane premixed gas, four types of water mist release positions and three particle sizes (8, 45, 80 μm) were designed. Results showed that，when the 8, 45，80 μm water mist was released at position 2, the pressure in the tube decreased by 36.59%, 65.85% and 31.7%, respectively. When position 3 is released, the pressure in the tube decreases by 34.15%, 56%, and 39.02%, respectively. 8 μm water mist has a significant inhibitory effect on the deflagration process, and has little effect on the flame structure and flame surface; 45 μm and 80 μm water mist have a significant impact on the flame structure and flame surface, and the flame surface appears wrinkled and divergently expands forward, and this effect becomes more obvious as the particle size of the water mist increases. The water mist mainly dilutes the premixed gas, reduces the local combustible gas concentration and vaporizes and absorbs heat on the flame. When the water mist is released above the obstacle closest to the ignition point and between two obstacles, the effect of suppressing deflagration in the tube is the most significant.

Key words: water mist, semi- open barrier pipeline, premixed methane gas, deflagration, suppression mechanism