Explosion venting of rich hydrogen-air mixtures in a small cylindrical vessel with two symmetrical vents

The safety issues related to explosion venting of hydrogen-air mixtures are significant and deserve more detailed investigations. Vented hydrogen-air explosion has been studied extensively in vessels with a single vent. However, little attention has been paid to the cases with more than one vent. In this paper, experiments about explosion venting of rich hydrogen-air mixtures were conducted in a small cylindrical vessel with two symmetrical vents to investigate the effect of vent area and distribution on the pressure buildup and flame behavior. Experimental results show that venting accelerates the flame front towards the vent but has nearly no effect on the opposite side. The maximum internal overpressure decreases while the maximum external flame length increases with the increase of the vent area. Two pressure peaks can be identified outside the vessel, which correspond to the external explosion and the following gas jet, respectively. Compared with the case of single vent, the use of two vents with same total vent area leads to nearly unchanged maximum internal and external overpressure but much smaller external flame length.