长直公路隧道火灾近火源区长度研究

Study on length of area near fire source in long-straight highway tunnel

为探究近火源区长度变化规律,以长直公路隧道为研究对象,利用量纲分析法推导近火源区长度关系式。采用FDS 6.2对42组工况进行数值模拟计算,分析火源功率、隧道断面形状两个因素对近火源区长度产生的影响。结果表明:隧道形状一定时,火源功率不断增大,烟气一维流动阶段起始点位置不断向后移动,近火源区长度不断增大。火源功率一定时,隧道断面高度不断增大,近火源区长度呈现逐渐减小的变化趋势;隧道断面宽度不断增大,近火源区呈现长度逐渐增大的变化趋势。根据模拟结果,明确了无量纲近火源区长度L*与无量纲火源功率Q*的1/3次方呈线性增长关系,建立了火源功率和隧道断面形状耦合作用下的近火源区长度预测模型。

In order to explore the variation rules of length of area near fire source,the relation formula of length of near fire source area was deduced by dimensional analysis method with research object of long straight highway tunnel.FDS 6.2 was used for numerical simulation calculation of 42 groups of conditions,and the influence of two factors of heat release rate(HRR)and tunnel section shape on the length of area near fire source was analyzed.According to the results of the simulation,when the tunnel is in a certain shape,with the continuous increase of HRR,the starting point of one-dimensional smoke spread stage moves backward continuously,and the length of area near fire source increases continuously.When the HRR is constant,the length of area near fire source de^creasesgradually with the increase of the tunnel section height,and increases gradually with the increase of width of the tunnel section.It is clear that there is a linear relationship between the dimensionless form of the length of area near the fire source and the 1/3 power of dimensionless HRR.A model for predicting the length of area near fire source under the coupling effect of HRR and tunnel section shape was established.