Study on gas explosion characteristics in a mixed environment of open-end rigid and flexible obstacles

The differentiation characteristics of gas explosion accidents in coal mine roadways are highly susceptible to the induction of facility layout and structural features within the field, which has long been a key challenge in prevention and mitigation of disaster.This study employs rigid and flexible obstacles to characterize fixed and non-fixed facilities in the roadway and investigates the gas explosion characteristics in a mixed environment of rigid and flexible obstacles open on the right end of pipelines.Based on the gas explosion experimental platform, the rigid obstacle and the flexible obstacle were placed at 40 cm and 50 cm away from the ignition end respectively.The blocking rate of the rigid obstacle was set at 0.4, and the blocking rates of the flexible obstacle were set at 0.2, 0.4, and 0.6 respectively.The flame propagation process and flame dissipation behavior in the closed and open environments on the right end of pipelines were carried out, as well as experimental studies on the evolution process of explosion pressure, etc.The experimental results show that the maximum flame interruption speed is at its highest when the blocking rate of flexible obstacles is 0.4, which can enhance the flame speed by 746.07% compared to the closed environment.In a mixed environment of rigid and flexible obstacles, when the right end is open, two peak pressure phenomena are presented.After reaching the first pressure peak, it linearly decreases to the maximum negative pressure and sexhibits a low-frequency, high-amplitude, and oscillation-increasing effect to form the second pressure peak.The first and second peak pressures reach their maximum when the blocking rate of the flexible obstacle is 0.2, with increases of 112.83% and 197.31% respectively compared to the conditions of a closed air duct.The variation in the velocity at the flame leads to different degrees of fuel and product discharge, creating a negative feedback mechanism on the maximum explosion pressure.Consequently, the maximum explosion pressure inside the pipe shows a trend of first decreasing and then increasing as the blocking rate of the flexible obstacle increases.The research results can provide certain theoretical guidance for prevention and mitigation of disaster in coal mine roadways.