Effect of multiple vent parameters on an external explosion induced by an indoor premixed methane-air explosion

To reveal the influence of vent parameters on the dynamic mechanism of an external explosion induced by a vented premixed methane-air explosion, the evolution process of an outdoor flow field under different vent opening pressures $(p_v)$, opening times $(t_v)$, and scaled vent size $(K_v=A_v/V^{2/3})$ is studied by methods of computational fluid dynamics. With an increase in $K_v$, the shape of the unburned gas cloud and vented flame gradually changes from a jet shape to a depression toward the vent. The outdoor peak specific turbulent kinetic energy increases by $36.5$ and $4$ times with an increase in $p_v$ and $t_v$, respectively. At $t_v=0.1$ s, the peak specific turbulent kinetic energy reaches $1411$ m$^2$/s$^2$ and the turbulence range reaches $3$ times the length of the room. With an increase in $p_v$, $t_v$, and $K_v$, the occurrence time interval of the external explosion exhibits a decreasing trend. The external explosion is located at a distance of less than $1.4$ times the length of the room. At $K_v=0.05$, the external explosion occurs at the furthest location.