Flame propagation and dust transient movement in a dust cloud explosion process

In recent years, dust explosion accidents have been reported frequently. More and more studies on dust explosions have been published. However, there are few reports concerning flame propagation and dust particle movement of a large-scale dust explosion process in open space. In this study, a large-scale corn starch dust explosion was simulated using computational fluid dynamics software. Flame propagation and particle transient movement during the explosion were monitored. The initial dust cloud, with a concentration of about 300 g m−3, is approximately an ellipsoid with a 4 m major axis (horizontal) and a 3 m minor axis (vertical); its center is at about 1.5 m distance from the ground. At the time of 700 ms when the explosion process basically finishes, the dust cloud expands to a semi ellipsoid with a 14 m major axis (vertical) and a 10 m minor axis (horizontal). The dust cloud volume expands to 366.92 m3, which is 14.60 times of its initial value (25.13 m3). During the explosion, both the flame and the dust cloud expansion are first accelerated and then decelerated, but overall, variation of dust cloud expansion velocity lags behind the variation of flame velocity. Before 400 ms, dust cloud expansion velocity is notably lower than flame velocity, then dust cloud and flame expand outwards together basically at the same speed, and the distance between dust cloud boundary and flame boundary stabilizes at around 0.5 m.