Previous studies have not focused on the effect of longitudinal ventilation on the temperature field with different transverse fire source locations in a branched tunnel fire. The maximum temperature under the ceiling is crucial for evaluating the thermal hazard of a tunnel fire. In this study, a series of reduced-scale branched tunnel fire experiments were conducted to examine the maximum excess temperature and longitudinal temperature decay, where the essential parameters of longitudinal ventilation velocity, fire source location, and heat release rate are varied. The influence of longitudinal ventilation on the temperature field near the fire source is clear, but less sensitive in the far field. The effect of transverse burner location on fire plume behavior is obvious, and the asymmetric thermal accumulation behavior was explored. Based on flame and plume inclination angle correlations, the maximum excess temperature model considering transverse fire location was developed and analyzed. The far-field temperature of diffusion smoke downstream is slightly greater than that upstream and ramp. The diversion ratio of diffusion smoke mass flow rate downstream is related to the longitudinal temperature decay coefficient. The diversion ratio of diffusion smoke mass flow rate downstream increases nonlinearly with the increasing dimensional longitudinal velocity. Further, the model was proposed to predict longitudinal temperature distribution downstream of the fire source in the main tunnel considering different transverse fire locations.

中文翻译：

---

不同横向火灾位置纵向通风分支隧道下游扩散烟气最高温度研究

以往的研究并未关注分支隧道火灾中纵向通风对不同横向火源位置温度场的影响。天花板下的最高温度对于评估隧道火灾的热危害至关重要。在本研究中，进行了一系列缩小规模的分支隧道火灾实验，以检查最大超温和纵向温度衰减，其中纵向通风速度、火源位置和热释放速率等基本参数发生变化。纵向通风对火源附近温度场的影响明显，但对远场的影响不太敏感。横向燃烧器位置对火羽流行为的影响明显，并探讨了不对称热累积行为。基于火焰和羽流倾角的相关性，建立并分析了考虑横向火灾位置的最大过温模型。下游扩散烟气的远场温度略高于上游和坡道。下游扩散烟气质量流量的分流比与纵向温度衰减系数有关。扩散烟气质量流量下游的分流比随着维度纵向速度的增加而非线性增加。此外，考虑到不同的横向火灾位置，提出该模型来预测主隧道火源下游的纵向温度分布。