通风和开口形状对地下硐室火灾影响的实验研究

Experimental study on influence of ventilation and opening shape on underground chamber fire

针对狭长通道侧向风和不同开口形状对硐室火灾燃烧状态及火焰溢流现象的影响,利用自主设计搭建的小尺寸实验台对侧向通风条件下地下硐室火灾燃烧规律进行研究。实验设定了200 mm×400 mm,300 mm×300 mm,400 mm×200 mm 3种硐室开口尺寸(长×高),选取1.2,3.3,5.1 m/s 3种通风速度和13.8,41.4,69.0 kW 3种火源功率。研究结果表明:在侧向风作用下,可燃气更容易被吹出造成火焰溢出燃烧现象;侧向风在中性面上部区域主要起降温作用,在中性面下部区域则起升温作用;通风因子大的开口工况,室内温度更高,也更容易达到轰燃条件;宽且低的开口使得高温气体与通风风流在较低处混合,其结果导致硐室下部温度较高,对火灾初期人员疏散不利。

Aiming at the influence of lateral wind in the long-narrow channel and different opening shapes on the combustion state and flame overflow phenomenon of the chamber fire at present,the combustion laws of underground chamber fire under the lateral wind conditions were studied by using the self-designed and self-constructed small-scale test bench.Three opening dimensions(length×height)of the chamber were set as 200 mm×400 mm,300 mm×300 mm and 400 mm×200 mm,then three ventilation speeds of 1.2 m/s,3.3 m/s and 5.1 m/s and three fire source power of 13.8 kW,41.4 kW and 69.0 kW were selected.The results showed that under the effect of lateral wind,the combustible gas was more easily to be blown out and cause the flame ejection combustion phenomenon.The lateral wind mainly played the role of cooling at the upper region of neutral surface,while the role of heating at the lower region of neutral surface.Under the opening condition with large ventilation factor,the indoor temperature was higher,and it was easier to reach the flashover condition.The wide and low opening made the high temperature gas and the ventilation air flow mix at a lower position,resulting in higher temperature at the lower part of the chamber,which was unfavorable for the initial personnel evacuation.