Influence on the methane/air explosion characteristics of the side venting position in a pipeline

To reduce the huge losses caused by natural gas explosions in transport pipelines, a small simulation pipeline with internal dimensions of 100 mm × 100 mm × 1000 mm was constructed, and the effects of the side venting position in the pipeline on methane explosion characteristics were studied. The experimental results showed that the venting effect of a side vent on flame propagation and explosion overpressure is not linearly increasing with shortening the distance between the side vent and the ignition point. The venting effect is significantly influenced by both the side venting position and the effect of an end vent. As the flame propagates upstream a side vent, the flame propagation is mainly affected by an end vent, and little affected by the side vent. Whereas when the flame propagates downstream the side venting position, the flame propagation velocity becomes to be gradually reduced by side venting effect. Besides, after a side vent is opened, the explosion overpressure is released by the side vent immediately, and the duration time of explosion overpressure is sensitive with the side venting position, but not in direct proportion with the peak overpressure. This illustrates the overpressure development affected by a side vent is influenced by both the side venting position and the interaction between the side vent and the end vent.