细水雾工作压力对综合管廊火场温度与烟气运移影响

The effect of fine water mist working pressure on the temperature and smoke transportation in the utility tunnel

为探究细水雾压力对综合管廊火灾温度场和烟气的影响,通过搭建1∶6缩尺管廊试验台,采用流量系数为3的细水雾喷头,设计了5种不同细水雾工作压力下的管廊火灾试验,对比分析5种工况下的管廊火灾温度场和烟气的变化规律。结果表明:适当增加喷雾压力能够提高细水雾的灭火效率,且随着细水雾压力的增加,管廊内烟气温度先大幅下降后缓慢降低,烟气流速减慢,烟气层高度下降;细水雾压力为2 MPa时,烟气温度比无细水雾时提前达到峰值,且峰值大幅降低,当压力达到4 MPa以后,温度峰值下降趋势变缓;温度分布呈逐渐衰减趋势,横向上火源中心处温度最高;在竖向上,距顶棚越近温度越高;不同细水雾压力作用下管廊顶棚横向温度分布和竖向温度分布均与指数模型拟合良好,通过指数模型能够预测出不同细水雾压力作用下的顶棚横向温度和竖向温度;压力为3 MPa时,细水雾对火灾的抑制作用和对烟气的排出效率均较高,设定细水雾压力参数时不应过大,以保证对烟气影响较小的基础上完成对火灾的抑制降温。研究结果为实际管廊细水雾灭火系统的设计优化和提高排烟效率提供参考。

In order to investigate the effect of fine water mist pressure on the temperature field and smoke of the utility tunnel fires,through the construction of 1:6 scaled corridor test bed,using the flow coefficient of 3 of the fine water mist nozzle,the design of the corridor fire test under five different fine water mist working pressure,comparative analysis of the corridor fire temperature field and smoke under the five conditions of the pattern of change of temperature field and smoke.The results show that:properly increasing the spray pressure can improve the fire extinguishing efficiency of the water mist,and with the increase in the pressure of the water mist,the flue gas temperature in the tunnel first greatly reduces and then slowly decreases,the flue gas flow rate slows down,and the height of the flue gas layer drops.When the pressure of fine water mist is 2 MPa,the flue gas temperature peaks earlier than when there is no fine water mist,and the peak value is greatly reduced;when the pressure reaches 4 MPa,the peak temperature decreases more slowly.In addition,it is found that the temperature distribution in the horizontal direction shows a gradual decay trend,with the highest temperature at the center of the fire source;in the vertical direction,the closer to the roof,the higher the temperature.The horizontal and vertical temperature distribution of the roof of the utility tunnel under different fine water mist pressures are well fitted with the exponential model,and the exponential model can predict the horizontal and vertical temperatures of the roof under different fine water mist pressures.Based on comprehensive analysis,the pressure of 3 MPa,fine water mist on the fire suppression and smoke discharge efficiency are higher,set the fine water mist pressure parameters should not be too large to ensure that the smoke has less impact on the basis of the completion of the fire suppression and cooling.The results provide a reference for the optimization of the design of water mist fire extinguishing systems and the improvement of smoke evacuation efficiency in utility tunnel.