Abstract
Combined with the k-ε turbulence model of general application, a refined finite element model of a utility tunnel’s gas compartment filled with the methane/air mixture is developed. A series of analyses are made by using the powerful industry-leading computational fluid dynamics (CFD) software flame acceleration simulator (FLACS) to study the shock wave propagation rule in the gas compartment. The longitudinal and transversal distribution laws of the explosion shock wave are gained taking into consideration the spatial characteristics of the gas compartment. The influences of a few parameters, such as initial conditions and section size of the gas compartment, on the shock wave propagation rule are further discussed. The basic procedure for predicting the peak pressure of the blast wave is provided by considering the initial conditions and the gas compartment, and the corresponding injury effect of the explosion wave on the living beings is assessed. The investigation demonstrates that the peak pressure by the coupled effect between the initial conditions is significantly influenced, especially at the upper and lower gas explosion limits. The peak pressure increases gradually as the width or height increases, and both basically meet the linear relation. The proposed method can forecast the peak pressure of the explosion shock wave in the gas compartment accurately. According to the peak pressure longitudinal and transversal distributions of the blast wave, the peak pressure is far greater than the killing pressure threshold in the underground and closed space; consequently, it is not safe for the living beings in the gas compartment.
Highlights
Nowadays, the process of the urbanization is accelerated constantly and the scale of the city is enlarged substantially in the last few decades. e municipal pipeline system becomes more and more complicated and its corresponding management issue becomes increasingly apparent [1, 2]
The larger the filled length of the gas is, the higher the peak pressure is. e maximum relative deviations between the simulated and fitting results are all less than 5%, indicating that the fitting and numerical simulation results coincide very well with each other, despite the filled length of the gas
The increasing trend decelerates with the distance away from the gas zone [39]. e peak pressure on the wall of the gas compartment increases by about 22.47% compared with the peak pressure at the center of the section when r r0. e maximum relative deviations between the numerical simulation and fitting results are small enough so that the fitting results match well with the simulated results
Summary
The process of the urbanization is accelerated constantly and the scale of the city is enlarged substantially in the last few decades. e municipal pipeline system becomes more and more complicated and its corresponding management issue becomes increasingly apparent [1, 2]. Taking into account the role of the hydrogen, Zhang et al [15] carried out the finite element analyses to examine the explosion of the methane/hydrogen mixture in the gas compartment of a utility tunnel by means of the commercial CFD analysis software FLACS. Combined with the typical urban gas explosion incidents [18,19,20,21] over the latest years, a range of finite element analyses are performed on a typical and representative gas compartment in a utility tunnel to research the propagation rule of the gas blast. A new methodology is presented to forecast the blast wave properties in the gas compartment [22, 23]
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