隧道内偏置火源顶棚近壁面温度边界层效应研究

基于隧道火灾不同横向火源位置的非对称卷吸影响，通过模拟计算分析了中心火源和偏置火源产生的烟气沿纵向最大温升变化规律，研究了顶棚下方近壁面区域内的不同温度分布，提出偏置火源纵向空间最大顶棚温升公式。结果表明:在壁面黏性作用下，沿纵向蔓延的烟气最高温度在顶棚下方呈现“温度边界层”分布；随着火源位置的偏移，下游出现偏置距离起主导作用影响温度衰减的区域，衰减速度相较于中心火源逐渐降低；火源下游近壁面最高温度位置逐渐远离顶棚后趋于稳定。研究结果对于排烟方式的设计以及空间通风效果的提升有着重要意义。

Research on temperature boundary layer effect at near wall of ceiling for offset fire source in tunnel

Based on the asymmetric entrainment effect of different transverse fire source locations in the tunnel fire,the change laws of the longitudinal maximum temperature rise of smoke generated by the central fire source and the offset fire source were analyzed through the numerical calculation.The difference of temperature distribution in the near wall area under the ceiling was studied,and the formula form of longitudinal maximum temperature rise at the ceiling for the offset fire source was put forward.The results showed that under the effect of wall viscosity,the maximum temperature of smoke spreading along the longitudinal direction under the ceiling presented the distribution form of “temperature boundary layer”.With the offset of fire source location,the area that the offset distance played the leading role to affect the temperature attenuation appeared in the downstream,and the attenuation rate was lower than that of the central fire source.The maximum temperature location near the wall gradually increased to a stable distance from the ceiling.