Effect of slit parameters on diaphragm rupture and self-ignition during pressurized hydrogen release

The effect of an extension tube with a rectangular slit inlet on the opening status of the metal diaphragm, as well as spontaneous ignition of pressurized hydrogen are experimentally investigated. The results show that the opening ratio of the metal diaphragm exhibits a positive correlation with the increase of the slit area. It also shows an initial increase followed by a decrease as the failure pressure rises. Moreover, the shock overpressure and Mach number inside the tube with the slit entrance are significantly reduced compared to those within the circular inlet tube. The critical pressure for spontaneous ignition in the tube with narrow inlet is notably affected by the slit parameters, increasing progressively with decreasing slit area and slightly increasing with raising slit aspect ratio. These experimental results would serve as valuable references for further exploring the failure modes of hydrogen storage containers and mechanisms underlying the spontaneous ignition.