Experimental and Numerical Studies on Longitudinal Smoke Temperature Distribution Upstream and Downstream from the Fire in a Road Tunnel

Four full-scale tests are conducted in a real road tunnel, with ceiling jet temperature distributions measured 200 m upstream and downstream from the fire. Two sizes of pool fires, 1.8 and 3.2 MW, with two different fire surface heights, 0.2 and 1.7 m from the floor level, are considered. Longitudinal ventilation velocities are also varied. The experimental data obtained in these four tunnel fire tests are used for validation of FDS 4.0 parallel simulation on tunnel fires. The ceiling jet temperature distributions upstream and downstream, and thus the back-layering length are compared. Results show that the temperatures predicted by FDS 4.0 are near to the measured data. In near fire regions, for instance, not more than 40–80 m away from the fire, the temperature predicted is very close to the full-scale data. There is a deviation between the predicted value and the measured one, shown to be mainly less than 4–5 C, at positions further away. The back-layering length predicted by FDS 4.0 also seems to agree fairly well with that deduced from the full-scale experiments.