Fire-induced flow temperature along tunnels with longitudinal ventilation

The temperature distribution of fire-induced flow beneath the ceiling of tunnels or corridors with longitudinal ventilation needs to be estimated in order to properly design the fire detectors and provide adequate fire protection to the tunnel structure. The authors’ previous correlation for naturally ventilated tunnels is evaluated to correlate the temperature distribution of fire-induced flow under mechanically ventilated tunnels. The effects of the longitudinal ventilation velocity and the fire heat release rate are introduced into this correlation by replacing the reference flow excess temperature and its position with the maximum flow excess temperature and its position, respectively. Experimental data ranging from reduced-scale to laboratory-scale tunnels from two past studies are employed. Supplementary data are obtained from numerical simulations. Several past empirical correlations for the maximum flow excess temperature and its position are validated with adjusted coefficients by these data. The evolved correlation for the temperature distribution of fire-induced flow along mechanically ventilated tunnels is finally evaluated and modified. Results indicate that this correlation could predict the temperature distribution with engineering accuracy.