Influence of side venting position on methane/air explosion characteristics in an end-vented duct containing an obstacle

To improve the discharging efficiency of a gas explosion in an end-vented duct containing an obstacle, a side vent in different positions was introduced to a duct with the internal dimensions of 100 × 100 × 1000 mm3. The flame propagation characteristics and overpressure profiles of a methane/air explosion were analyzed to study the influence of side venting position on a gas explosion in an end-vented duct containing an obstacle. The experiment results showed that, the explosion can be efficiently discharged by a side vent in a duct containing an obstacle, and the discharging effect can be enhanced significantly with shortening the distance between the side vent and the ignition point. Besides, the relative position of a side vent and an obstacle has significant influences on the venting effect of a side vent. For a side vent located in front of an obstacle, the explosion can be effectively discharged by the side vent before the flame reaches the obstacle, thus dropping the incentive of the obstacle on flame propagation, and resulting in a great venting effect. Whereas for a side vent located behind an obstacle, before the flame reaches the side vent, the flame propagation will be strongly motivated by the obstacle and maintained at a high speed to pass the side vent, which is not conducive for a side vent to discharge the explosion. In addition, when the explosion overpressure induced by an obstacle is much higher, the discharging effect of a side vent on explosion overpressure can be further enhanced, resulting in a greater venting efficiency.