Fire Safety Science Digital Archive

To determine the key features of the fire safety design in transversely ventilated tunnels, smoke propagation characteristics are evaluated as a function of fire size, fire location and flow rates of supply and exhaust. A model of the Memorial tunnel is used. The scale-down ratio of its cross-section is 1/20 and its length is 12m. Fire sizes and ventilation rates in real tunnels are calculated by Froude similarity. In general, it is found that the smoke propagating distance is proportional to the fire size and is inversely proportional to the exhaust ventilation rate. When the location of the fire is off-centered, the smoke propagating distance increases remarkably as compared with a centered-fire scenario. A hazardous situation generated from an imbalance between the supply rate and the exhaust rate is also observed. Based on the results, smoke propagating distance and the ratio of supply to exhaust are suggested as criteria for fire safety design of a transverse ventilation system