高层建筑火灾时烟气的垂向组合控制研究

高层建筑火灾时,正压防烟带入的大量新鲜空气被送入着火层并稀释了烟气,降低了机械排烟效率。采用垂向组合控制的模式,对高层建筑内烟气流动采用双方程三维紊流模型,通过实验和模拟对比分析各排烟模式的排烟效果。结果表明,对条形走廊,单独设置空气幕能有效阻挡烟气进入前室,但防烟时间相对较短,同时采用空气幕和正压时,挡烟时间至少增加了60 s,且挡烟效果和单独前室正压相同,但所需新鲜空气量却减少了1/3,且此模式下的烟气在空气幕和前室正压作用下经过两次降温,温度下降效果明显,在竖井中容易形成滞止状态,使烟气在中性层上方向其他楼层扩散的趋势降低,对整栋楼内人员疏散更为有利。

Study on Vertical Combination Smoke Control Model for High- rise Building Fires

In high-rise building fires,a large amount of fresh air can be pressurized into the fire floor when smoke prevention system is used,which dilutes the smoke and reduces the efficiency of mechanical smoke exhaust.The vertical composition smoke-control model is put forward to control the smoke.The k-ε three-dimension turbulence model with two equations are used and the influences of smoke exhaust effect with different smoke control modes are analyzed by simulation and experiments.The results show that: for strip corridor,when the air curtain is alone set up,the smoke can be effectively blocked into the atria in short time relatively.While using air curtain combined with positive pressure,the smoke control time at least increases 60 s,and this composition model has the same effect as atria pressurization,but the amount of fresh air is decreased 1/3.The smoke has two processes of cooling in the effect of air curtain in the corridor and the pressure air in the atria,so the smoke of lower temperature is easy to be stagnant status and the tendency of spreading to other floors is reduced obviously,beneficial to the evacuation in the whole building.