One of the initiatives to decarbonize railways is the development of fuel-cell vehicles. However, in order to put fuel-cell railway vehicles into practical use, it is necessary to confirm their safety. One particularly important issue in confirming safety is the evaluation of hydrogen concentration in the event of a hydrogen leak in a tunnel. In this study, a numerical analysis was performed to investigate the hydrogen leak flow from a stationary railway vehicle in a tunnel. The results showed that the leaked hydrogen rose toward the crown of the tunnel and flowed toward both tunnel portals. The hydrogen concentration was the highest immediately above the leakage point and decreased rapidly toward both tunnel portals. Additionally, the influence of the location of the leak on the hydrogen concentration distribution was also shown.
Fukuda et al. (Sun,) studied this question.