喷水灭火和纵向通风耦合作用下隧道火灾烟气输运规律与控制研究

It is difficult to exhaust fire smoke from tunnels because of the relative enclosed structure of tunnels, which is the leading reason of casualties in tunnel fires. Therefore, the emergency ventilation systems has been regarded as the most important fire protection facilities in tunnels since a long time ago. With the increased application of the Water spray-based Fixed Fire Fighting System (WFFFS) in tunnels, great attention has been paid on the negative effect of the suppression on the fire smoke control in tunnels. However, relative studies in this field are rare to be found. Accordingly, this project is mainly focused on the tunnels with longitudinal ventilations, and would systematically investigate the tunnel fire smoke movement under the combined effect of suppression and longitudinal ventilation by experimental and theoretical analyses. Based on all the foregoing work, the backlayering rules of the tunnel fire smoke under the collaboration of the suppression and longitudinal airflow, as well as the suppression effect on the stratification of the backlayering would be revealed. Furthermore, the suppression efficiency under the effect of the longitudinal air flow would be studied. Finally, the optimal design and control strategy of the WFFFS and the longitudinal ventilation system would be proposed to reduce the negative impact of the suppression on the fire smoke control in tunnels. The outcomes of this project would provide the references for the theory and the application of WFFFS in the longitudinal ventilation tunnels.

由于隧道相对封闭的空间构造，火灾烟气不易被排出，是造成隧道火灾伤亡的主要原因。因此长期以来，通风排烟系统被视为隧道最重要的消防设施。随着固定喷水灭火系统愈发广泛地应用于隧道，业界开始关注喷水灭火对隧道火灾烟气控制的不利影响，但相关的研究工作甚为缺乏。基于现状，本项目立足于纵向通风排烟的隧道，拟借助实验模拟和理论研究，系统地研究喷水灭火和纵向排烟耦合作用下火灾烟气的输运规律，由此一方面揭示喷水颗粒和纵向风耦合作用下隧道火灾烟气的回流规律，另一方面揭示喷水作用下隧道回流烟气层的沉降特性。在此基础上，结合纵向通风对喷水灭火效率的影响研究，综合提出隧道喷水灭火系统和纵向通风排烟系统的优化布置方案和控制策略，确保在满足火势控制的同时，最大程度地降低喷水对火灾烟气控制的不利影响，为固定喷水灭火系统在隧道中的应用提供理论依据和应用参考。

由于隧道相对封闭的空间构造，火灾烟气不易被排出，是造成隧道火灾伤亡的主要原因。 因此长期以来，通风排烟系统被视为隧道最重要的消防设施。随着固定喷水灭火系统愈发广泛地应用于隧道，业界开始关注喷水灭火对隧道火灾烟气控制的不利影响，但相关的研究工作甚为缺乏。本项目立足于纵向通风排烟的隧道，借助实验模拟和理论研究，系统研究喷水灭火和纵向排烟耦合作用下火灾烟气的输运规律。本项目搭建了1：14和1：3两个缩尺寸隧道火灾实验平台，实验研究了在喷水颗粒和纵向风速耦合作用下，隧道内水雾强度分布特征和隧道火灾烟气回流输运规律，揭示了水雾抑制火灾烟气回流机制，建立了隧道火灾烟气回流长度预测模型；研究了临界风速随火源功率、火源高度和喷头特性的变化规律，建立了隧道火灾临界风速模型；开展实验揭示了不同通风条件下，喷头排数、压力和位置等因素对回流烟气沉降的影响作用，并基于CFD模拟方法，准确模拟了水雾诱导火灾烟气沉降现象，揭示了准静态烟气在水雾作用下的沉降机理，通过敏感性分析获得诱导烟气沉降的关键水雾参数；考虑喷头类型、喷头布置、喷水压力和纵向风速等因素，观测了喷水与纵向风耦合条件下典型火源形态特征，揭示了喷水灭火系统的火灾抑制和环境冷却效果。基于项目研究成果，综合提出隧道喷水灭火系统和纵向通风排烟系统的优化方案和控制策略，确保在满足火势控制的同时，最大程度地降低喷水对火灾烟气控制的不利影响，为固定喷水灭火系统在隧道中的应用提供了理论依据和应用参考。