Flame morphology of dual jet fires ejected from a spherical tank

Abstract Dual jet fires occur when a storage tank has two leakage points or two adjacent tanks leak simultaneously. Currently, research on inclined dual jet fires is limited. In this paper, an experimental setup is constructed to simulate dual jet flames confined by a hemispherical wall, and the merging behavior and flame length are intensively investigated in terms of different exit velocities, nozzle inclination angles, and nozzle diameters. As the exit velocity increases, the flame merging probability first increases and then decreases to a certain level for d = 2.3 mm, while for d = 3 mm, its variation pattern has no fixed trend. Meanwhile, the flame length initially increases, and then remains almost constant until Fr ≥ 10 5 . When the nozzle inclination angle decreases, for d = 2.3 mm, there is no fixed trend in the flame merging probability, while for d = 3 mm, the flame merging probability first decreases and then increases to reach one. In addition, the flame length first decreases, then increases, and finally decreases again with the decrease of nozzle inclination angle in both Fr < 10 5 and Fr ≥ 10 5 cases. The dimensionless flame lengths are quantitatively expressed based on air entrainment analysis.