内廊式建筑火灾外部烟气蔓延规律

Spreading characteristics of external smoke for buildings with internal corridor

为了探究内廊式建筑火灾外部烟气蔓延规律,以某内廊式建筑为研究背景,通过数值模拟研究不同火源特征参数下外部烟气的形成机理及蔓延规律.研究发现:火灾前期,室内烟气会发生溢出形成外部烟气,在临近上层走廊重新进入室内,导致温度在短时间内显著增大,随后外部烟气逐渐减少,温度逐渐降低并保持稳定;当火灾规模较小时,火源位置变化对外部烟气蔓延的影响不显著,火灾规模较大时,火源位置存在明显的危险区段:火源处于该区段中,外部烟气的影响程度显著增大,在区段外影响程度较低,危险区段为距离通风口4.5~6.5 m;临界风速可以作为判断烟气是否溢出的有效判据,当室外补风气流速度大于临界风速时,烟气发生溢出形成外部烟气,反之则不会形成.

The influence of external smoke under different fire characteristic parameters was analyzed in order to analyze the spreading characteristics of the external smoke. One building with internal corridor was analyzed through numerical simulation. Results show that the external smoke will re-enter the adjacent floor and result in the significant increase of temperature in fire initial stage. Then the temperature will decrease and unchange due to the decrease of external smoke volume. When the fire scale is small, the fire location has no significant effect on the external smoke. When the fire scale is higher, the influence of fire location has the dangerous area. If the fire location is in the dangerous area, the impact degree of external smoke will significantly increase and the degree of that will decrease if the fire location is out of the dangerous area. The dangerous area is 4.5 m to 6.5 m away from the vent.The critical velocity of wind can be the criterion that determines whether smoke spills out. If the wind velocity is higher than the critical velocity, the smoke will spill out;if not, the smoke will not spill out.