地铁车站发生火灾时施加水平细水雾幕抑制顶棚射流火焰的有效性

针对施加竖向细水雾幕的缺陷,对水雾喷头进行改进,使之产生水平向的细水雾幕。以某地铁车站为原型设计试验台,通过室内试验研究水平雾幕对地铁车站火灾的挡烟、隔热及顶棚射流火焰抑制、烟气沉降抑制的有效性。结果表明:施加水平雾幕具有较大的水平动量,雾通量在喷头前方呈均匀分布,而施加竖向雾幕其雾通量集中在喷头下方;施加水平雾幕对顶棚射流火焰具有显著抑制作用,火焰长度减小约40%,且火焰不能穿越雾幕;施加水平雾幕的隔热效率均比施加竖向雾幕高10%左右,且施加水平雾幕对烟气层的扰动更小,雾幕作用区烟气沉降幅度较小;施加水平雾幕后方有明显的烟气分层现象,且烟气最高温度、烟气出口速度均小于施加竖向雾幕。

Effectiveness of Applying Horizontal Fine Water Mist Curtain to Suppress Jet Flame on Ceiling in Case of Fire in Metro Station

For the defect of applying vertical fine water mist curtain,the nozzle was improved to form a horizontal fine water mist curtain.The experimental platform was designed based on a metro station,and a series of laboratory tests were conducted to study the effectiveness of applying horizontal water mist curtain on smoke blockage,heat insulation,ceiling jet flame suppression and smoke deposition suppression in metro station fire.Results showed that the horizontal water mist curtain had larger horizontal momentum,and the mist flux was uniformly distributed in front of the nozzle,while the vertical mist curtain was concentrated under the nozzle.The jet flame on the ceiling could be effectively suppressed by applying horizontal water mist curtain.The jet flame could not cross the mist curtain and its length decreased about40%.The heat insulation efficiency of horizontal mist curtain was about 10%higher than that of the vertical one.Besides,the disturbance of smoke layer was smaller when the horizontal mist curtain was applied,and the range of smoke deposition within the active region of mist curtain was smaller.There was obvious smoke stratification behind the horizontal mist curtain.Moreover,both the maximum smoke temperature and stack gas exit velocity under the horizontal mist curtain were smaller than those under the vertical one.