地下汽车库车辆火灾蔓延及机械排烟措施

Study on the Effect of Vehicle Fire Spread and Mechanical Smoke Extraction in Underground Garage

目的研究地下汽车库火灾兼有的液体和固体火灾的特点,以及不同机械排烟措施对火灾烟气的控制效果.方法采用FDS模拟软件对地下汽车库火灾进行了数值模拟,分析了不同排烟量下地下汽车库火灾的发展态势,火灾释热速率的变化,以及中央通道1.8m高度处的平均温度、二氧化碳浓度.结果当换气次数为30次/h时,安全疏散时间达到350s;当换气次数>40次/h时,350s以后仍然可以满足人员可利用安全疏散时间的要求,但火灾释热速率在250～350s区间的增值幅度和梯度比较大.结论机械排烟造成火灾释热速率有所升高,不利于灭火,但通道处的温度、二氧化碳浓度均有明显下降.合理的机械排烟系统有利于人员的安全疏散.

FDS is used to simulate and analyze the development of vehicle fires in underground garage, the changes of the heat release rate, the average temperature and concentrations of carbon dioxide on the Z = 1.8 m plane of central corridor in condition of the different mechanical exhausts smoke volume. The results show that the heat release rate increases under the effect of mechanical smoke extraction, which is adverse to fire. But both the temperature and concentration of carbon dioxide on central corridor are decreased. This illustrates that mechanical smoke extraction system has contribution to human evacuation safety. When the mechanical exhausts smoke volume is 66 150 m3/h, Available Safety Evacuation Time （ASET）is 350 seconds. When the volume is more than 88 200 m3/h, ASET meets the requirement of safety evacuation, but the heat release rate increases obviously before 350 seconds.