Studies On Thermal Physics Of Smoke Movement In Tunnel Fires

Tunnel fire safety is a special topic of fire research. More and more tunnels had been constructed in the recent years with the fast development of economy. Tunnel makes traffic more convenient, but also brings about many new fire safety problems for us. Tunnel fire has attracted more and more research attention due to the fire disasters occurred in tunnels in recent years. Statistics showed that smoke was the most fatal factor in fires, especially in tunnel fires where much toxic gases were released due to incomplete combustion. Smoke control is very important for saving lives in case of a tunnel fire. However, in order to provide appropriate fire safety, the physics of smoke spreading in tunnels should be well understood first.The interaction of the three factors: the fire induced buoyancy, the confinement of long-narrow configuration of tunnel and the longitudinal ventilation wind, makes the movement of smoke induced by fire in tunnels much more complex than that in normal compartment. In this thesis, full/large scale experiments were conducted, along with theoretical analysis and CFD numerical simulation, to study the dynamics and thermal physics of fire induced smoke movement in tunnels. Some key problems at different development stages of smoke layer in tunnels were studied and resolved. These findings were also applied to the design and management of smoke control systems in case of tunnel fires. Works include:Large/full scale fire experiments were conducted in a 96m underground long model tunnel and three real road tunnels with length of about 2700m, 3200m and 1024m. Dynamic and thermal physics characteristics, including smoke temperature field, smoke layer traveling velocity, smoke layer height distribution and back-layering distance, were measured. These experiments systematically provided important large/full scale data for tunnel fire research.A model was built for predicting the smoke layer temperature decay in the longitudinal direction in tunnel fires. The traditional two-layer zone model can not...