无纵向风下环境压强对拱顶最高温度影响数值研究

为了给高海拔隧道火灾防灾救援设计提供参考依据,通过火灾动态模拟软件(FDS)建立全尺寸模型隧道,设置5种不同环境压强,研究环境压强对隧道火灾拱顶最高温度的影响。结果表明： 1)相同火源热释放速率(HRR)下,拱顶最高温度随着压强降低而增大; 2)环境压强降低引起的空气密度与卷吸强度变化是造成拱顶最高温度变化的主要原因。基于理论分析和数值计算结果,提出考虑环境压强的拱顶最高温度预测模型。预测模型拱顶最高温度与考虑环境压强的无量纲热释放速率的2/3次幂成正比,试验数据验证了预测模型的可靠性。

Numerical Study on Influence of Ambient Pressure onMaximum Temperature ofTunnelCrown without Consideration of Longitudinal Velocity

In order toprovide a reference for the design of fire prevention and rescue in high altitudetunnel, a full scale model tunnel is established byfire dynamics simulator(FDS), and 5 different ambient pressures are provided.And then the influence of different ambient pressures on the maximumtemperature around tunnel crown in case of fire is studied. The study resultsshow that: (1) Under the same heat release rate(HRR), the maximum temperaturearound tunnel crown increases with the decrease of ambient pressure. (2) Thevariation of air density and entrainment strength caused by the decrease ofambient pressure is the main factor causing the maximum temperature variationaround tunnel crown. A prediction model for the maximum temperature aroundtunnel crown considering ambient pressure is proposed based on theoreticalanalysis and numerical simulation results. The prediction model shows that themaximum temperature around tunnel crown is proportional to the 2/3 power of thedimensionless HRR considering the ambient pressure. Finally, the reliability ofthe prediction model is verified by the existing model test data.