纵横向排烟与障碍物阻塞效应耦合作用下隧道火灾烟气输运行为研究

Under coupling conditions of longitudinal ventilation, transverse point extraction and blockage blocking effect, the tunnel fire smoke flowing behavior will be complicated compared with that under single condition. By theoretical analysis, small-scale experiments and numerical simulation, this research focuses on the investigation of tunnel fire smoke flowing characteristics under combined influence of longitudinal ventilation, transverse point extraction and blockage blocking effect, which includes: (1) The coupling influence of longitudinal ventilation, transverse point extraction and blockage blocking effect on flow field near the fire and their further influence on fire plume deflection and entrainment is analyzed and a theoretical model to predict the maximum temperature for fire smoke under the tunnel ceiling is developed; (2) Considering the combined influence of longitudinal ventilation velocity, transverse point extraction velocity, blockage ratio and the horizontal distance between fire and blockage on characteristic parameters for fire smoke back-layering (as temperature decreasing distribution, smoke back-layering length, critical velocity), theoretical models are developed to correlate smoke back-layering characteristic parameters with fire heat release rate, characteristic velocity, blockage ratio, and the horizontal distance between fire and blockage under such conditions in order to modify previous classic models. The coupling influence of longitudinal ventilation, transverse point extraction, and blockage blocking effect on tunnel fire smoke flowing behavior has rarely been considered for current researches. The above models proposed by this research will be able to improve the classic models under such complex coupling conditions, and will be further valuable for tunnel ventilation and smoke extraction design in case of a fire.

在纵向排烟、横向集中排烟和障碍物阻塞效应耦合作用下，隧道火灾烟气输运行为呈现复杂特殊性。本项目拟采取理论分析、结合小尺寸和数值模拟研究，阐析该复杂耦合边界条件下隧道火灾烟气输运特性：（1）耦合分析纵向排烟、横向集中排烟和障碍物阻塞效应对近火源流场的作用机制及其对火羽流倾斜及卷吸的影响行为，建立隧道顶棚烟气最高温度预测模型；（2）综合考虑纵向排烟风速、横向集中排烟风速、障碍物阻塞比及其与火源之间距离对烟气逆流行为特征参数（温度衰减、逆流长度、临界风速）的影响机制，建立纵横向排烟和障碍物阻塞效应耦合作用下烟气逆流行为特征参数与火源功率、特征风速、障碍物阻塞比及其与火源之间距离的表征模型，对原有经典预测模型进行修正。当前关于隧道火灾烟气输运行为的研究尚未考虑纵横向排烟和障碍物阻塞效应的耦合作用，本项目有助于弥补经典理论在该复杂耦合边界条件下的不足，对于隧道火灾的通风排烟设计，也具有参考价值。

在障碍物阻塞效应作用下，隧道火灾烟气输运行为呈现复杂特殊性。现有隧道火灾理论模型未考虑障碍物对隧道排烟通风流场的阻塞效应，不能对其作用下的隧道火灾烟气输运行为进行描述。本项目拟通过理论分析和小尺寸实验，结合数值模拟研究，揭示该复杂边界条件下隧道火灾烟气输运特性。（1）揭示障碍物阻塞效应对隧道排烟通风流场的作用机制，以及对火羽流倾斜和卷吸的影响行为，建立了考虑障碍物阻塞比和障碍物-火源之间距离的烟气最高温度预测模型。（2）分析了不同障碍物阻塞比以及障碍物-火源之间距离条件下隧道火灾烟气逆流长度演化规律，建立了考虑障碍物阻塞比因子的烟气逆流长度预测模型。（3）分析了障碍物阻塞效应作用下控制烟气逆流所需的临界控制风速，揭示了临界控制风速随障碍物阻塞比以及障碍物横截面布置方式的演化规律。（4）开展了列车火灾火溢流顶棚射流烟气温度分布实验研究，建立了烟气最高温度和纵向温度分布预测模型。项目完成了预定的研究目标和成果指标：已在国际著名学术期刊发表SCI论文6篇，包括International Journal of Heat and Mass Transfer，Applied Thermal Engineering，International Journal of Thermal Sciences，Tunnelling and Underground Space Technology等国际权威学术期刊；项目培养硕士研究生1名；项目注重学术交流合作，累计参加国际学术会议1次，参加全国性学术会议7次。