Through the comparison between the actual situation and steady state, the following conclusions could be concluded that the first three temperature stages near to the right side of fire source in actual situation and temperature ranges of influence were larger than the steady state. The influence of temperature range of the fourth stage was smaller than the steady state and it had a sudden drop tendency instead of decreasing slowly. In the steady state, the influence of temperature range between 315K to 322.5K kept the highly consistent with fire source until the exit of tunnel. However, the temperature of this range was irregular and the temperature in the middle of the tunnel on the right of fire source increased which was near to the roof of tunnel and smoke outlet compared to the steady state. The temperature of roof of the tunnel on the right side of the smoke outlet, it still kept between 307K to 315K which was near the ground.
(3) Assumed that there was a fire caused by a bus spontaneous combustion in the tunnel, the change rules of buses’ heat release rate can be pided into three stages. When the time of x between 0s and 180s, the heat release rate is y=x/9; When the time of x between 180s and 730s, the heat release rate is y=20; When the time of x between 730s and 780s, the heat release rate is y=-2x/5+212; The numerical simulation is according to the above formula.
Through the comparison between the actual situation and steady state, the following conclusions could be concluded that the speed on the right side of the fire source was mainly pided into two parts which decreased from large to small and changed rapidly and it was apparently inconsistent with the actual situation. The velocity of upper and lower sides of tunnel was relatively slow while the velocity of middle of the tunnel was fast; The velocity of the upper right of the fire source which was near to the right smoke outlet was faster than below because of the restriction of fire source. The fourth temperature range on the right of fire source was the same height as the fire source which increased when it come to the end and the temperature decreased rapidly; The variation trend of temperature which was the nearest to the tunnel exit was relatively rapid.
(4) Assumed that there was a fire caused by a bus spontaneous combustion in the tunnel, the change rules of velocity of tunnel entrance can be imported to FLUENT through UDF to conduct numerical simulation.
The temperature range on the right of the fire source becomes rapid because of the fire restriction and the influence of the velocity direction in the tunnel when the velocity of entrance changed. The differences in temperature had reach approximately 35K. The temperature continuously decreased along the positive direction of Y axis, and the temperature range between 315K to 323K decreased rapidly to the range between 308K to 315K. The influence of temperature range was far less than the steady state. Another big difference is that the temperature from 308K to 315K in the 2/3 section tunnel on the right side of fire source increased along the positive direction of Z axis.
Compared to the simulation result at steady situation, the simulation results of the changes of heat release rate and inlet velocity through this paper with different types of vehicles made this paper closer to the actual situation and provided the method of research and design and the results on the ventilation situation when the tunnel is on fire for scholars and people who need to design the tunnel ventilation as a reference in the future.
Keyword： tunnel fire；numerical simulation；vehicle type；heat release rate；inlet velocity
目 录
1 绪论 1
1.1设计目的和意义 1
1.2 文献综述 2
1.2.1 隧道火灾的国内外研究现状 2
1.2.2 FLUENT软件 4
1.3 论文的设计内容 5 FLUENT基于UDF模拟的某隧道通风优化设计(3):http://www.751com.cn/gongcheng/lunwen_11807.html