Numerical simulation of hydrogen leakage and explosion characteristics in hydrogen fuel cell buses under different window-opening conditions and wind directions

With the large-scale deployment of hydrogen fuel cell buses, operational safety concerns have become increasingly prominent, particularly the risks associated with hydrogen leakage and subsequent explosion, which warrant thorough evaluation. Using the Computational Fluid Dynamics (CFD) simulation software, a three-dimensional physical model was constructed based on a specific hydrogen fuel cell bus prototype to systematically investigate the leakage and dispersion characteristics of hydrogen within the cabin, as well as the associated combustion and explosion hazards, under varying numbers of open windows and wind directions. The results indicate that hydrogen leakage in a confined space exhibits pronounced vertical concentration stratification. The number of open windows significantly influences the distribution of the hydrogen concentration field within the passenger cabin. However, when the number of open windows is held constant, the impact of different window opening locations on the hydrogen volume fraction at a given monitoring point is relatively minor. Furthermore, when the explosion overpressure generated by the ignition of the leaked hydrogen exceeds the ultimate load-bearing capacity of the window glass, the glass fractures, thereby achieving pressure relief. A comprehensive assessment reveals that the high-temperature thermal hazards induced by hydrogen combustion are significantly greater than the blast overpressure hazards in confined-space combustion and explosion scenarios.