扁平大空间建筑烟气蔓延影响因素研究

为研究扁平大空间内烟气蔓延影响因素,通过FDS火灾模拟软件对上海某商业综合体的商场进行模型建立,利用计算机模拟,逐一研究了水喷淋,挡烟垂壁高度,排烟口大小、数量,补风方式、补风量对烟气蔓延的影响,通过对比得出结论:增加挡烟垂壁高度对烟气蔓延影响有限,而去除水喷淋对烟气蔓延速度及质量浓度影响最大,烟气蔓延至各测点时间最多加快超过100 s,各测点烟气单位长度消光率最多上升69.51%/m;减小补风量至50%与去除水喷淋对烟气分布影响效果相当,在进行防排烟设计优化时,应优先考虑水喷淋与补风量;此外排烟量保持不变,改变排烟口数量及大小对烟气影响主要体现为蔓延速度变化。

Trace and pursue of the influential factors of the smoke spread around the large flat-space buildings

The present paper intends to establish a model of a commercial center in Shanghai to study the effects of water spray,smoke blocking wall height,smoke exhaust vent size and quantity,air supply mode,air supply volume and other factors on the spread of smoke in flat large space by using the software known as FDS. Comparing the effects of the different operating conditions,we can arrive at the following conclusions: the average time length the smoke spread to the measuring points may increase by 20 s when the smoke block wall height increases from 0. 5 m to 1 m. The smoke unit length extinction rates tend to reduce by less than 10%/m. Although the smoke blocking wall height increase can slow down the smoke spreading and the smoke exhaust rate, other factors also have more significant effects on the smoke spreading relatively,too. For instance,water spraying has the greatest impact on the smoke concentration and smoke spreading speed,too. Without the water spray system,the smoke spreading time length to the measuring points might have accelerated by over 100 s,and the smoke unit length extinction rates may have increased by 69. 51%/m at most. Also,a 60% decreasing of the supplementary air volume can cause the smoke concentration to ascend with the maximum increase of the smoke unit length extinction rate of each measuring point by a percentage of 42. 34%/m,whereas the smoke exhaust rate may get to decrease. The supplementary air volume reducing to 50% has a similar effect on the smoke concentration with the water spraying removing system. Therefore,the influence of the water spraying system and supplementary air volume shall be prioritized for designing or optimizing this type of flat great space building discussed in this paper. Increasing or decreasing the number of smoke exhaust vents with the same smoke exhaust rate may not affect the smoke concentration obviously,but the system can affect the smoke spreading speed primarily. Therefore,in engineering designs,the number and distribution of smoke exhaust vents should be determined in combination with the economic cost and the availability based on the regulation requirements of the smoke control and exhaust.