Study on explosion characteristics of hydrogen in a sudden expansion pipe

Abstract

ABSTRACT As a promising green energy source, the risk of hydrogen explosion cannot be ignored. In the industrial environment, the connection between factories and different regions may form a mutated structural space. This structure may have a significant impact on the consequences of hydrogen accidents, which is worthy of study. In this research, the simulation method is used to analyze the explosion and combustion process of hydrogen flame propagation in a sudden expansion pipe, which focuses on the impact of the cross-section ratio. The results indicate that due to the influence of Rayleigh-Taylor instability, the flow field in the dead zone near the sudden expansion structure can be unstable and generate vortices, which will significantly change the development of gas combustion and explosion. Under the extrusion and entrainment of vortices, the flame front structure is changed from finger-like flame to mushroom-like flame. When the flame enters the downstream pipe section through the expansion port, the impact of vortices on the flame propagation velocity is changed from suppression to excitation, and the excitation effect is closely related to the cross-section ratio. At the cross-section ratio μ = 3, the maximum flame propagation velocity and maximum pressure growth rate of the downstream pipe are 198.7 m/s and 53.12 MPa/s, respectively, which are 68.8% and 151.4% times higher than those in the case of the cross-section ratio μ = 1.5. There is a remarkable impact of sudden expansion structure on flame propagation and explosion overpressure.