Explosion venting processes and venting enhancement methods of the coal mine air shaft

In order to disclose the explosion venting processes of the air shaft of coal mines and explore the venting enhancement methods, a series of full-size 3D simulation models based on the current explosion door were established for the current explosion method and several improved ones, and fluid-structure coupling simulations were carried out using the CESE solver of LS-DYNA. The results show that the current explosion door will cause strong reflected shock wave and can not weakened it quickly and effectively during the explosion venting, resulting in two shock waves to occur in the fan drift and secondary impact on the main fan. It has no obvious effect on venting enhancement to remove the ring part of the current explosion door, but the impact on the explosion door can be significantly reduced. It has limited effect on venting enhancement to reduce the mass of the explosion door within the feasible range, and the explosive energy absorbed by the explosion door increases dramatically. Comparatively, it can effectively enhance explosion venting effect by increasing the distance between the explosion door and the branch point of the air shaft and the fan drift. Both lateral and vertical advance explosion venting methods can significantly enhance the venting effect, the pressure peak of the reflected shock wave can be reduced respectively by 49.4% and 28.3% under the given conditions. There are three key factors found to affect explosion venting effect, one is the opening time of the explosion door, another is explosion venting area, the third is the distance between the explosion door and the branch point of the air shaft and the fan drift. The opening time of the explosion door to achieve favorable explosion venting effect is much shorter than that of the current explosion door. There is a latent limitation to setting an single explosion door on the top of the air shaft, that is, the pressure peak of the first shock wave in the fan drift can not be reduced no matter how to vent. Based on the above results, a cooperative explosion venting method characterized by two zones and multiple ducts was proposed.