关键词: 分岔隧道, 强羽流, 临界温度, 火焰面积, 热释放速率(HRR)

Abstract: In order to explore transverse and longitudinal length and flame area distribution features of ceiling jet flow driven by strong plume in a bifurcation tunnel, 5 groups of fire locations (0.1, 0.3, 0.5, 0.7 and 0.9 m) and 4 HRR (47.9, 63.8, 77.7 and 95.7 kW) were selected. Transverse lengths of intermittent flame and transverse continuous flame for typical working conditions were calculated and corresponding critical temperature values were determined, which were 325 and 620 ℃ respectively. Based on critical values of continuous flame, its transverse and longitudinal flame length as well as flame area were obtained. The results show that there is a non-monotonic trend for transverse flame length as distance from fire source to sidewall increases from 0.1 m to 0.7 m, and it will reach maximum value at 0.3 m. Nevertheless, longitudinal length continuously decreases as distance rises from 0.1 m to 0.9 m, and it is always larger than transverse length under same conditions. Flame area increases first with spacing grows from 0.1 m to 0.3 m and then decreases as it continuously increases to 0.7 m.

Key words: bifurcation tunnel, strong plume, critical temperature, flame area, heat release rate(HRR)