Influence of vent duct bend angle on inner dust explosion

A visualized tank was applied to carry out explosion venting experiments to investigate the effect of the bend angle of the vent duct on the venting dynamics process during the dust explosion. By changing the bend angle of the duct and comparing the conventional ductless and straight duct venting, the distribution law of venting overpressure and the development process of flame shape in the duct and container were analysed. There are typically three-peaked features in the duct caused by film-breaking shock waves, secondary explosions, and continuous combustion of the flame in the container. The secondary explosion strength in the duct increases with the bend angle, which exacerbates the severity of the explosion compared to conventional ductless or straight duct explosions. In the case of bend venting, as the bend angle of the duct increases, the Pmax and the (dP/dt)max all show an increasing trend in the container, and the Pred,max difference on both sides of the bend is positively correlated with the bend angle. In addition, with an increase in the bend angle, the total reaction time in the container gradually decreased, namely, the flame duration shortened.