Numerical simulation of explosion characteristics of premixed stoichiometric hydrogen/air in low pressure environment

As the construction of highway tunnels in China gradually expands to high-altitude regions, the application and transportation of hydrogen will inevitably involve these areas. However, as altitude increases, atmospheric pressure decreases significantly, and the low-pressure environment has a significant effect on the explosion characteristics of hydrogen, resulting in varying degrees of explosion hazard. To investigate the hydrogen explosion characteristics under different low-pressure conditions, this study modified a multi-phenomenon combustion model suitable for simulating spherical explosions in low-pressure environments. Considering the heat transfer mechanisms, numerical simulations of stoichiometric hydrogen/air explosions in a spherical vessel were performed, and the results were validated against experimental data. The results indicated that the effects of flame instability and heat loss on overpressure increased as the initial pressure decreased. Specifically, when any factor contributing to flame instability was neglected, both the peak overpressure and its rate of increase decreased significantly. Conversely, when the effect of heat loss was ignored, both the peak overpressure and its rate of increase significantly increased. In addition, the study showed that with the reduction in initial pressure, there was a corresponding decline in both peak overpressure and the rate of overpressure rise. This phenomenon was primarily attributed to the significant reduction in the mass of reactants and their consumption rate at lower initial pressures, which subsequently led to a decrease in the energy released. • The multi-phenomenon combustion model for spherical vessels has been modified. • The effect of heat loss on explosion increases as the initial pressure decreases. • Flame instability affects explosions more at lower initial pressure. • The reactant consumption rate has a significant effect on pressure in low-pressure.