通风对竖井型隧道火灾烟气特性影响试验研究

通过隧道火灾模型试验，研究纵向通风对竖井排烟效果及隧道内纵向烟气温度分布的影响。试验考虑不同火源热释放速率和纵向风速。结果表明：纵向风速对正庚烷池火热释放速率存在影响，对于较小正庚烷池火（≤11 cm），火源热释放速率基本不随纵向风速而改变；对于较大正庚烷池火（≥14 cm），火源热释放率随风速的增加先降低后基本保持恒定。此外，当隧道内风速较小时，竖井内烟气附壁排出，竖井后方烟气温度较低，控烟效果较好；当隧道内风速较大时，竖井内烟气出现边界分离，竖井后方温度升高，烟气蔓延距离增加，竖井排烟效果较差。因此，建议当竖井型隧道内发生火灾时，应尽量采用自然通风或较低的内部通风，避免较高风速。

Experimental study on the smoke properties under longitudinal ventilation in a tunnel with vertical shafts

This paper experimentally studied the influence of the longitudinal ventilation on the smoke exhaust performance of the vertical shaft and the ceiling temperature distribution. HRR and longitudinal ventilation velocity were considered during the fire tests. The results show that ventilation velocity has an impact on HRRs of heptane. For small square pool fires (≤11 cm) , HRRs keep approximately constant regardless of the ventilation velocities while for relatively large square pool fires (≥14 cm), HRRs decrease initially and then keep approximately unchanged with the increase of the ventilation velocities. Besides, when the ventilation velocities in the tunnel are low, the smoke is exhausted from the shaft by adhering the shaft sidewalls, and the smoke temperature on the downstream side of the shaft is low, indicating a good exhaust performance. When the ventilation velocity in the tunnel is high, the boundary separation in the shaft occurs and the smoke temperature downstream the shaft is high, and the smoke moves further, indicating a low smoke exhaust efficiency of the shaft. Therefore, it is suggested that in a naturally ventilated tunnel fire, low velocity can be employed, but the high ventilation velocity should be avoided.