Numerical Simulation of Spatial Distribution Characteristics of Hazardous Gas Clouds from Leakage at a Hydrogen-Blended Natural Gas Distribution Station

Abstract Blending hydrogen into natural gas pipelines is widely regarded as a promising transitional pathway for large-scale H2 transport; however, it inevitably increases the risk of leaks and explosions at urban distribution stations. This computational fluid dynamics (CFD) study models a typical gas distribution station, employing LFL isosurface area and volume to evaluate the effects of the hydrogen blending ratio (HBR), operating pressure, leakage aperture, wind speed, wind direction, and leak direction on hazardous gas cloud evolution. The results show rapid initial growth in both surface area and volume; the surface area subsequently stabilizes, while the volume continues to rise, indicating continuous hazard zone expansion. A higher HBR broadens the LFL isosurface and promotes a vertical dispersion. Wind speed has a nonlinear influence, while wind direction and leak orientation govern accumulation patterns through the building obstructions. Sensitivity analysis identifies leakage aperture and leak direction as the most influential continuous and categorical factors, respectively, with operating pressure ranking second and HBR and wind speed ranking third. These findings provide support for safety distance determination, leakage aperture monitoring, and emergency response planning for hydrogen-blended gas distribution stations.