隧道内不同横向位置双火源顶棚最大温升试验研究

Experimental study on the maximum temperature rise of the ceiling with dual fire sources at different transverse positions in a tunnel

为分析自然通风隧道内双火源的顶棚最大温升,在不同火源边长、火源间距、火源横向位置3个影响因素下,采用隧道模型(与实际隧道的比例为1:10)在实验室内进行77组双火源火灾试验,与9组单火源火灾试验对照,分析3个影响因素对顶棚最大温升的影响。结果表明:双火源间距相同时,火源边长越大,顶棚最大温升越大;火源间距和火源横向位置对顶棚最大温升影响显著;火源边长和双火源间距相同时,火源位于贴壁位置时的顶棚最大温升最大;单火源燃烧时,随火源逐渐远离侧壁,顶棚最大温升先减小后增大;双火源间距较大时,随火源逐渐远离侧壁,顶棚最大温升一直减小;火源边长相同时,随双火源间距增大,火源位于同一位置的顶棚最大温升基本呈减小趋势。将Alpert顶棚最高温升预测模型与Zukoski镜面效应相结合,可较准确地预测单火源位于贴壁位置时的顶棚最大温升;双火源位于不同隧道横向位置时的归一化顶棚最大温升均随无量纲火源间距的增大而减小。

To analyze the maximum temperature rise of the ceiling in a natural ventilation tunnel with two firesources,a total of 75 sets of dual fire source fire tests are conducted in a tunnel model(scaled at 1:10 compared to the actual tunnel) under three influencing factors:fire source edge length,distance between fire sources,and lateral position of fire sources.These results are compared against 9 sets of single fire source fire tests to examine the impact of the three factors on the maximum temperature rise of the ceiling.The results indicate that:when the distance between dual fire sources is the same,a larger fire source edge length leads to a greater maximum temperature rise of the ceiling;the distance between fire sources and their lateral position significantly affect the maximum temperature rise of the ceiling;when the fire source edge length and distance between dual fire sources are the same,the maximum temperature rise of the ceiling is greatest when the fire source is positioned against the wall;during single fire source combustion,as the fire source gradually moves away from the side wall,the maximum temperature rise of the ceiling first decreases and then increases;when the distance between dual fire sources is relatively large,the maximum temperature rise of the ceiling continuously decreases as the fire source moves away from the side wall;when the fire source edge lengths are the same,as the distance between dual fire sources increases,the maximum temperature rise of the ceiling when the fire sources are in the same position generally shows a decreasing trend.By combining the Alpert ceiling maximum temperature rise prediction model with the Zukoski mirror effect,a relatively accurate prediction of the maximum temperature rise of the ceiling can be made when a single fire source is positioned against the wall;the normalized maximum temperature rise of the ceiling for dual fire sources located at different transverse positions in the tunnel decreases with the increase of the dimensionless distance between fire sources.