This paper explores the effects of an abrupt cross-section area change of gas pipes on the propagation law of explosion. For this, an explosion pipe experimental system was established, and a numerical research was conducted. By experimental and numerical simulation, the evolution of the overpressure, temperature, vorticity, and kinetic energy of shock waves of gas explosion in abrupt pipelines was investigated. This allowed us to obtain expressions for the attenuation coefficient, increase coefficient, and reflection coefficient of gas explosion overpressure. The study indicates that an abrupt increase of the pipeline cross-section area leads to a decrease of shock wave overpressure and vice versa. For a given change of cross-section area, the attenuation coefficient gradually increases as the initial peak overpressure rises, whereas the increase coefficient and reflection coefficient both present a decreasing trend. An abrupt change in the pipe structure can inhibit the propagation of gas explosion flames. The explosive gas is affected by the turbulence effect after passing through the middle large-diameter pipe, and the vorticity curve exhibits a clear peak. In addition, the large eddy motion caused by strong confinement increases the kinetic energy of the gas in pipes. The above research outcomes contribute to further enriching the basic theory of gas explosion for the study of gas explosion propagation in mining laneway.

Understanding the principle underlying the coupling between coal seam stress and gas pressure will help prevent the occurrence of dynamic coal and gas disasters. However, previous studies have mainly focused on the macroscopic...

Methane drainage using boreholes is one of the most effective means of preventing coal mine methane disasters. However, the distributions of stress and permeability around the borehole and the effective influence radius of methane...

Spontaneous combustion of residual coal in the goaf can be readily caused by the oxygen supply of air leakage to the goaf of shallow coal seam due to surface fractures. Different ventilation methods of working face will have a certain impact on the surface air leakage characteristic. In this study, based on Bulianta 22310 working face and Huojitu 12 _down 206 working face, by combining air leakage measurement, numerical simulation, surface fracture investigation with dual tracer technology, a three-dimensional permeability model was established to research qualitatively and quantitatively the surface air leakage characteristics in the shallow coal seam composite goaf with various ventilation methods. The findings indicate that the main zones of the effective surface air leakage fractures and the surface air leakage in the goaf are significantly different with different ventilation methods. The main effective surface air leakage fracture zone with extraction ventilation is larger than that with press-in ventilation. The main zone of the surface air leakage in the goaf is 285–315 m along the working face inclination direction and 0–30 m along the working face strike direction on the return side with extraction ventilation. With press-in ventilation, the main surface air leakage zone in the goaf is 0–40 m along the working face inclination direction and 0–37 m along the working face strike direction on the intake side. Based on the main zones of the effective surface air leakage fractures and the surface air leakage in the goaf, pressure equalization technique and burying surface fractures are applied to treat surface air leakage, and their effectiveness is confirmed by air leakage measurement and dual tracer technology. This study has a guiding role in the precise treatment of surface air leakage in composite goaf of shallow coal seams.