Effects of the length and pressure relief conditions on propagation characteristics of natural gas explosion in utility tunnels

With the development of urbanization, the construction of the utility tunnel facilitates people's lives, but also brings some new potential hazards. For example, gas explosion occurring in the natural gas compartment can pose great threats to the safe operation of utility tunnels. In this paper, an experimental apparatus for modeling the process of the natural gas explosion in utility tunnels is established to investigate the effects of the gas compartment length and pressure relief conditions on the flame behaviors, and several parameters related to the consequence severity of gas explosion are studied comprehensively. The results indicate that ancillary facilities in the natural gas compartment (seen as obstacles) that cannot generate the large-scale recirculation zone but cause the small size of turbulence. The maximum overpressure firstly increases and then decays with the increase of the length of the gas compartment. Besides, it is also found that different pressure relief locations and strengths have a great influence on explosion characteristics in utility tunnels. This study can provide technical supports for safe management of utility tunnels. Meanwhile, some suggestions are put forward for the explosion suppression techniques and the design of pressure relief ports in the utility tunnel.