Study on flame merging behavior and air entrainment restriction of multiple fires

Fire is a typical thermal runaway process of uncontrolled energy release. The possible ignition of adjacent leaked fuel might induce multiple fires burning simultaneously. A series of numerical simulations have been conducted to study the flame merging behavior and air entrainment restriction effect from square propane fire arrays. The simulation results were first systematically compared to experimental data, showing that the flame characteristics including the flame height, flame centerline temperature, and velocity distributions can be successfully reproduced numerically. Then, the flame merging phenomenon was studied by varying fire spacing, the number of fires, and the heat release rate of an individual fire in the array. Results show that the critical flame merging spacing of the fire array equals to 0.4 times the flame height of a single fire, which is independent of the fire array size. More importantly, a parameter denoting the extent of air entrainment restriction α was introduced, which enables a characterization of the air entrainment restriction effect of a fire array. A maximum air entrainment restriction model was established, which is shown only related to the number of fires in the array.