Numerical simulation of the effect of obstacle locations inside pipelines on spontaneous ignition resulted from high-pressure hydrogen leakage

In the process of hydrogen storage and transportation, if the high-pressure hydrogen in the storage tanks is released suddenly into the downstream pipelines, spontaneous ignition may occur, which can result in jet fire or explosion accidents. The obstacles such as the valves and welding slags inside the pipelines may affect the process and mechanism of spontaneous ignition of the leaked hydrogen. Therefore, a Computational Fluid Dynamics (CFD) model for the spontaneous ignition as a result of the high-pressure hydrogen leakage was developed and its reliability was validated by the experimental data. Subsequently, simulation analysis was performed for the spontaneous ignition process resulted from the high-pressure hydrogen leakage under the effect of obstacles at different locations in the pipelines. The results show that, the presence of obstacles has a significant influence on the shock wave propagation process in the pipelines, the variation of shock waves shows sensitivity to the obstacles, and the presence of obstacles in the pipelines will promote the flame propagation. In addition, the presence of obstacles increases the possibility of hydrogen spontaneous ignition in the pipelines, and the reflected shock waves generated by the obstacles will significantly change the spontaneous ignition mechanism of hydrogen. Generally, the research results could provide useful references for the design and safe operation of hydrogen pipelines.