Large-eddy simulation and experimental study on effects of single-dual sparks positions on vented explosions in a channel

Accidental fuel fire and explosion events, were often ignited by more than one spark, its characteristics evolution and influence mechanisms also deserved more attentions. Hence one and two sparks were respectively installed in a 10 L channel to investigate the influence of sparks positions on explosion characteristics via changing the distance between sparks and vents (Ip, dimensionless IpD, where D denotes channel diameters). The flame propagation and flow field coupling under typical single-dual sparks were revealed via LES simulation. Results indicate that simulated results are in good agreement with experimental data in terms of flame propagation process whether with single or dual sparks. For the cases with single spark, the pressure rise was mostly governed by flame expansion in the vent direction, whereas the opposite flame grew slowly or even stagnated, resulting in a clear positive linear correlation between Pmax and IpD. For the cases with dual sparks, if the dual sparks were at same pipe ends (Ip1D = Ip2D), explosion damage was as hazard as a single spark. When Ip1D≠Ip2D, the explosion risk rose considerably, the Pmax establishment process would vary with Ip2D. There was a positive linear correlation between Pmax and Ip2D, that was appropriate for different fuel equivalent ratio. These results may provide preliminary data for further understanding of explosion characteristics evolution under multi-sparks conditions.