Numerical simulation on explosion venting processes and venting enhancement methods of the coal mine air shaft based on CESE method

In order to disclose the explosion venting processes of the air shaft and explore the venting enhancement methods in coal mines, a series of full-size 3D simulation models had been established for the current and several improved explosion venting methods, and the whole process of fluid- solid coupling simulations analysis was carried out using the CESE solver of LS−DYNA software. The results shown that, the current explosion-proof door will cause strong reflected shock wave and cannot be quickly and effectively attenuated during the explosion venting process, resulting in the emergence of two shock waves in the air tunnel that can cause secondary impacts on the air turbine. Removing the explosion-proof door wall structure to enhance the effect of explosion venting was not obvious, but can make the explosion-proof door to the impact of a significant decrease. Within a feasible range, reducing the mass of the explosion-proof door to improve the effect of explosion venting was more limited, and will make the explosion-proof door absorbed by the explosion energy increased significantly. In small increments, increasing the distance from the explosion-proof door to the intersection of the air shaft and air tunnel can improve the effectiveness of explosion venting. Both lateral and forward advance explosion venting methods can significantly enhance the venting effect, and there was a significant shock absorption and protection for explosion-proof door. Optimized to reduce reflected wave overpressure peak by 49.4% and 28.3% under arithmetic conditions. The opening time of the explosion-proof door, the area of explosion venting and the distance from the explosion-proof door to the intersection of the air shaft and air tunnel were key factors in the effectiveness of explosion venting. The opening time required to achieve a favorable explosion venting effect in the air shaft was much shorter than that of the current explosion-proof door. The limitations of setting explosion-proof door only at the shaft entrance cannot reduce the overpressure peak of the first shockwave in the air tunnel. Based on the new understanding of the explosion venting process, mechanism and method of air shaft, a coordinated explosion venting method of main and auxiliary explosion-proof doors characterized by “two-area multi-channel” was proposed to systematically improve the venting effect and the explosion-proof level of air shaft.