Numerical simulation of secondary explosion in the external flow field after horizontal explosion venting of a narrow and long vessel

Numerical simulation was conducted to investigate the secondary explosion in the external flow field following horizontal explosion venting of a narrow and long vessel. The study utilized Fluent software, employing the standard k–ε turbulence model and SIMPLE algorithm, to analyze the secondary explosion under different explosion venting pressures, equivalence ratios, and length–diameter ratios. The results show that after the explosion of the pipeline, the flame lagging behind the pressure wave ignites the residual methane discharged into the external flow field again, which is the cause of the secondary explosion. When the explosion venting pressure exceeds 240 kPa, a distinct peak in overpressure is observed in the external flow field with its strength and range increasing proportionally to the venting pressure, reaching a maximum influence range of 0.4 m. At an explosion venting pressure of 290 kPa, three explosions can be detected. The equivalence ratio primarily affects the overpressure rise rate within the container prior to membrane rupture but has no significant impact on secondary explosion intensity. On the other hand, the length–diameter ratio significantly influences the overpressure rise rate within the container before membrane rupture as well as affecting secondary explosion intensity.