Study on Gas Explosion Characteristics in Urban Utility Tunnels

In order to study the effects of three factors, namely, premixed gas concentration, number of pressure relief ports and number of obstacles, on the overpressure characteristics of gas explosion and flame structure of gas chambers in utility tunnels, in this paper, a small and narrow experimental platform for gas explosion was constructed to study the evolution mechanism and law of the kinetic characteristics and flame behavior of gas explosion in utility tunnels, with a view to revealing the special influencing mechanism of the overpressure characteristics and flame behavior of gas explosion in utility tunnels. The results show that in the methane concentration of 9.5% when the explosion overpressure reaches its peak, and at the same time by the utility tunnel long and narrow restricted space, the explosion generated by the precursor shock wave along with the flame compression wave were superimposed on both ends of the pipeline back and forth for many times so that the overpressure waveforms are cyclic oscillatory trend, increasing the explosion hazards; compared with the closed conditions, the relief port on the overpressure characteristics of the significant impact of the maximum decrease of 57.7%, when the frequency of overpressure oscillation is reduced, the gas explosion generated by the overpressure damage is reduced; the presence of obstacles significantly affects the flow field, accelerates the flame propagation and leads to greater overpressure peaks and overpressure oscillations. The conclusions of the study can provide a basis for the safety of natural gas in utility tunnels.