火源—竖井间距对自然通风隧道火灾烟气流动特征的影响

Impact of the fire-shaft distances on the smoke flow properties in naturally ventilated tunnel fires

通过数值计算,研究顶部开口自然通风隧道火灾火源–竖井间距对烟气流动特征与竖井排烟效率的影响。考虑因素有火源–竖井间距、竖井断面尺寸。结果表明:随着火源–竖井间距的增大,竖井前方来流烟气的质量流量增大,且竖井的排烟效率逐渐降低,竖井内空气卷吸量减少;当火源–竖井间距较小时,竖井更有利于排出更多的热量,竖井后方的温度降低幅度更大,烟气可以被控制在更小的范围内。此外,随着竖井截面尺寸的增大,竖井的排烟效率增加,且增大竖井的宽度更有利于增加竖井的排烟量。因此建议当相邻竖井的间距较大时,可适当增加竖井的截面尺寸和竖井高度。

The impact of fire-shaft distance on the smoke flow properties and smoke exhaust efficiency in naturally ventilated tunnel fires was studied by numerical simulations.The fire –shaft distance and the cross-section of the shaft are taken into consideration.The numerical simulation results indicate that with the increase of the fire-shaft distances,the mass flow rates of the incoming smoke before the shaft increase,however the smoke exhaust efficiency and air entrainment of the shaft decrease.Besides,when a small fire-shaft distance is employed,more heat can be exhausted and lower temperatures downstream the shaft can be generated,and the smoke can be controlled within a small range.Moreover,as the shaft cross-section increases,the smoke exhaust efficiency of the shaft becomes great and more smoke can be exhausted under a wider shaft.From the resulted obtained in this work,when a large interval of adjacent shafts is set,it is suggested that a large shaft cross-section and a large shaft height be used.