Spatio-temporal evolution patterns and quantitative risk assessment of liquid hydrogen leakage accidents: Based on full-cycle numerical simulation

To characterize the dispersion of hazardous substances following liquid hydrogen leakage and to assess potential combustion and explosion risks, a comprehensive numerical model has been developed, encompassing liquid hydrogen leakage, gas-liquid heat and mass transfer, flammable cloud dispersion, combustion, and explosion. It reveals the full-cycle spatiotemporal evolution of risks associated with liquid hydrogen leakage accidents in open spaces and quantifies hazardous zones and safety distances under various conditions. The results indicate that the propagation of explosion overpressure in open spaces is closely related to the spatial configuration of the flammable cloud, with cloud volume being the primary determinant of explosion intensity. During continuous leakage, increasing the ignition delay from 10 s to 40 s expands the fatality zone by three times and increases the hazard zone by approximately 43%, with the maximum safe distance reaching 258 m. For time-limited leakage scenarios, both cloud volume and overpressure initially increase before subsequently decreasing. Furthermore, in large-scale unconfined flammable cloud explosions, the hydrogen concentration at the ignition source has a negligible effect on far-field overpressure, with predicted safety distance variations of less than 2.5%. This study provides a theoretical foundation for determining safety distances and for designing emergency measures in hydrogen-related scenarios.