Effect Of Longitudinal Ventilation On Burning And Smoke Movement In Road Tunnel Fires

With the convenient transportation to us, tunnels brings many new problem about fire preventation. Compares with the general buildings, due to the tunnel's own structure characters, there is always longitudinal wind in the tunnel. When the exhaust equipments start, the longitudinal wind becomes stronger. Therefore, study the tunnel fire character under longitudinal wind is very important. The research in this dissertation includes the following aspects:The relation between the burning rate of pool fire and the wind speed in tunnels. Pool fire is the most common style of fire. Its burning rate can not only express how fast the pool fire burns, but also determine some other character such as flame height, temperature of flame, and the distribution of heat radiation around the pool fire. The longitudinal wind has major impact on the burning rate of pool fire in tunnels, however few relevant research was about it. This dissertation gives the burning rate of pool fire in tunnels under different longitudinal wind speed, which was developed through a series of experiments in the combustion-wind-tunnel.The character of temperature field near the vault of tunnel above the fire source. A part of tunnel vault may be in fire plume when a fire occures, its mechanical performance will have big change under the high temperature, even structural destruction can take place. Therefore the study on the character of temperature field near the vault of tunnel above the fire source is particularly important. The present research indicated that, the tunnel vault's maximum temperature forecast model which obtains by Hitoshi Kurioka et al under scale experiment is able to use in the real tunnel. However, the model can only forecast the vault's maximum temperature , which can't forecast temperature rising pattern in the fire growth period. This dissertation gives the maximum temperature rising rate near the vault of tunnel above the fire source, and some suggestion were proposed about the settings of line-type heat detector in tunnels.Behavior of the flow field under the jetfan in tunnels. Jetfan is the most common smoke control equipment in the tunnel. Accoding to the present fire prevention control mode, as long as the tunnel fire occurs, the jetfan system should start immediately. This dissertation studied the flow field near the jetfan after it started with the numerical simulation method, as well as the effect to the stability of smoke layer near the fire source and nearby tunnel. Finally, according to the numerical simulation results, some proposals about the operation of jetfan in tunnel fires were put forward. Smoke control in road tunnel with service tunnel. Many road tunnels have service tunnel, and the service tunnel is designed to be a evacuation passage for vehicles and people in emergency. Therefore, how to assure the safety of evacuees is very important. The dissertation studied two fire control scheme, a suitable one was proposed for this road tunnel in case of fire. Finally, an evacuation method for both people and vehicles is planned based on the principle which let the people and vehicles evacuate separately.