Experimental investigation on the shock wave and spontaneous ignition of high-pressure hydrogen released into a tube through different narrowness inlets

Due to the high probability of hydrogen leaking from narrow cracks of the vessels, an experimental study is conducted to investigate the spontaneous ignition of high-pressure hydrogen released into a tube through inlets with different narrowness, including circular, square (length-width ratio x = 1), and two slit shapes of x = 2 and 3, with the same area. Pressure transducers and photoelectric sensors are used to detect shock wave dynamic variation and ignition occurrence. The results indicate that narrow inlets weaken the shock wave intensity and speed, and the weakening effect increases with narrowness. Moreover, spontaneous ignition is affected. The minimum burst pressure required for spontaneous ignition is higher in the cases with square and slit inlets. Most significantly, when x is 3, it is 2.5 times that of circular inlet. Meanwhile, for narrow inlets, the ignition flame intensity and speed are enhanced, and the inlet of x = 2 has the greatest impact.(c) 2023 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.