Investigation on flame propagation characteristics and critical ignition criteria of hydrogen jet

Hydrogen leaks form storage tanks or pipelines could be ignited easily and causes jet flame accident. To better understand the hydrogen jet flame ignition, we experimentally studied the flame propagation characteristics and critical ignition criteria in present work. Based on the flame propagation process after ignition, the flame could be divided three types: upstream propagation flame, stagnant flame and downstream propagation flame. The temperature of different types of flame was also investigated. The result indicated that the high temperature zone was similar to the flame propagation direction. In addition, the maximum ignition distance under different conditions was studied. The maximum ignition distance was increased with the increasing of gas flow rate and jet nozzle diameter. Furthermore, to qualitatively explain the ignition, a criterion based on a critical Damköhler number was formulated to demonstrate the coupling effect of flow rate, nozzle diameter and ignition distance.