环境压力对隧道火灾自然通风烟气特性的影响研究

Study on the Influence of Ambient Pressure on Natural Ventilation Smoke Characteristics of Tunnel Fire

采用数值模拟的方法,对不同环境压力下隧道火灾自然通风的烟气特性进行研究。首先建立三维数值模型,并采用试验数据进行验证,然后用验证后的数值模型,对环境压力分别为60kPa、80kPa、100kPa隧道火灾自然通风的烟气特性进行研究。研究结果表明,随着环境压力的降低,隧道顶壁下烟气温度上升、流速增大、浓度增加、能见度增加,同时根据竖井后方烟气特性的变化规律可以得出,随着环境压力的降低,竖井的排烟效果逐渐变差。这意味着环境压力对隧道火灾自然排烟完全排烟的临界竖井高度也有影响。

Numerical simulation is used to study the smoke characteristics of natural ventilation in tunnel fire under different environmental pressures.Firstly,the three dimensional numerical model is established and verified by the test data.Then,the verified numerical model is used to study the smoke characteristics of natural ventilation of tunnel fire under the ambient pressure of 60kPa,80kPa and 100kPa respectively.The results show that with the decrease of environmental pressure,the smoke temperature rises,the flow rate increases,the concentration increases and the visibility increases.At the same time,according to the change law of smoke characteristics behind the shaft,it can be concluded that with the decrease of environmental pressure,the smoke exhaust effect of the shaft gradually deteriorates.This means that the environmental pressure also has an effect on the critical shaft height at which the tunnel fire natural smoke is completely vented.