Experimental study on the influence of adding ventilation facilities on the overpressure propagation of gas explosion in the branch of “F+L” type pipe network

Gas explosion shock wave overpressure over a fairly long distance to the ventilation facilities have a strong destructive effect, in order to explore the complex network of ventilation facilities on overpressure the propagation of gas explosion, designed and constructed a “F + L” type gas explosion combined pipe network experimental system, the study of different methane concentrations （6%, 8%, 9.5%, 11%, 13%） in different working conditions on the peak change rule of gas explosion overpressure propagation. The results show that: on the cross-section mutation section explosion overpressure increase, straight pipe section explosion overpressure drop and bifurcation pipeline main section explosion overpressure change by the methane explosion gas volume fraction of the impact of methane gas volume fraction mainly affect the range of 11% to 13%. Among them, the methane volume fraction 6% of the overpressure growth rate is the largest, 9.5% of the growth rate is the smallest. In the straight pipe section, the shock wave overpressure gradually decreases during the propagation process. The decrease rate of overpressure value shows a trend of decreasing and then increasing with the increase of methane volume fraction, and it has an obvious “grouping effect”. In the branch section of the bifurcated pipeline, the explosion overpressure attenuation is mainly affected by the methane concentration and the additional ventilation facilities of the branch pipeline, the explosion overpressure value of the main pipeline in the section of the bifurcated pipeline with the increase in the concentration of pre-mixed gases shows a trend of increasing and then decreasing, the methane volume fraction of 9.5% is the largest, and the main pipeline is bigger than the bifurcated pipeline explosion overpressure value. Under different working conditions, the pressure value at measurement point 9 in the bifurcated pipeline is approximately equal to the value at measurement point 3 in the straight pipeline section. Compared with the normal ventilation facilities, the strengthened ventilation facilities are more resistant to shocks. The research results can provide reference significance for the scientific and reasonable installation of ventilation structures in coal mines and reduce the damage caused by gas explosion to the ventilation system.