Large Eddy Simulation on the Effect of Smoke Exhaust Openings Arrangement on the Smoke Spread in Tunnel Fires

AbstractThis paper reveals effect of smoke exhaust openings arrangement on the smoke spread performance in the tunnel fire of semi-transverse smoke extraction mode. Results show that the smoke back-layering can be significantly affected by the upstream openings arrangement in tunnel fires. As the more exhaust openings added to upstream, the smoke back-layering length becomes stronger and smoke spread rate remarkably increase. Moreover, the maximum smoke temperature above the fire source also remarkably increase due to combined effect of longitudinal air flow and the amount of smoke exhaust increased in upstream from the fire. Consequently, the fire risk to the blocked occupants and the tunnel structure increase in upstream. This research can contribute to the design of fire safety facilities and management of fire emergency in tunnels with similar conditions