Effect Of Several Factors On Combustion And Explosion In Underground Utility Tunnels Effect Of Several Factors On Combustion And Explosion In Underground Utility Tunnels

China will build a number of internationally advanced underground utility tunnel in 2020,which means that the construction and municipal planning of China's underground utility tunnel will move forward to a new height.The gas pipeline leakage and explosion accidents in the underground utility tunnel system are very harmful and destructive,and the technical research on the safety prevention of the underground utility tunnel and the technical specifications for the utility tunnel are not perfect.Therefore,it is particularly important to carry out relevant research on the explosion in the utility tunnel,provides reference for revisions of the specifications,and provide theoretical supports for the safe operation of the utility.In reality,the gas explosion occurs in places like obstacle ventilation equipment,machinery equipment,a variety of piping supports and the analog.The existence of obstacles has a significant incentive to the explosion pressure and flame propagation speed of natural gas.Although the underground comprehensive pipeline corridor has an independent gas compartment,it is susceptible to pipeline aging and corrosion during the operation of the gas pipeline.Leakage,and spread and gather in the enclosed space.When temperature reaches the ignition temperature or encounters a spark,the natural gas is directly ignited,and it may even explode within the explosion concentration range of natural gas,and the excitation of the flame due to the built-in pipe bracket as an obstacle is likely to cause significant damage to the pipe corridor personal injury and property loss property loss,even personal injury.In addition,serious flammable gas explosion accidents occur in large restricted spaces,such as underground oil depots,coal mine tunnels,various chemical plants,etc.,and the research rules are mostly based on small-scale experiments.In this paper,the numerical simulation method is used to study the law of combustion and explosion in the utility tunnel,and the influence of large-scale spaces such as underground utility tunnel on the flame propagation law.This paper simulates the explosion process of methane-air premixed gas in a closed space with built-in obstacles by using the time-averaged equation system,k-? turbulence model,and EBU-Arrhenius combustion model in ANSYS FLUENT software.The numerical simulation flame front is in good agreement with the experimental photographs,which validates the effectiveness of the mathematical model and calculation method.Based on the validation results of the mathematical model,a numerical simulation of the deflagration process in the gas bin of the integrated tube corridor with built-in obstacles was carried out,and the effects of the ignition source position and the size of the pipe gallery on the deflagration process in the gas bin of the integrated tube corridor with built-in obstacles were further discussed.The research shows:1.When the ignition source is consistent with the level of the obstacle,the flame is most disturbed.The lower half of deflagration flame is just blocked by the obstacle.The generated turbulence interferes with the direction of the forward propagation of the flame,and the flame has movement trend.2.When the distance between the ignition source and obstacle is different,the explosion pressure changes in the same direction,and the maximum explosion pressure is about the same pressure.The horizontal distance is closer to obstacle,the rate of pressure rises more slowly.3.Under certain conditions such as combustible gas concentration,the size of the space has a great influence on flame propagation speed.The development process of deflagration flames in small-scale spaces is faster than the development process of deflagration flames in large-scale spaces.4.The maximum value of explosion pressure in different spatial scales is approximatelythe same pressure,and the time to reach the maximum explosion pressure increases with theincrease of scale.5.The space size has no effect on the final temperature.As the size of the space increases,the rate of temperature rise decreases,and the time the temperature begins to rise increases,but the final explosion temperature is the same.