风环境下高层建筑外开口烟气溢流行为与扩散特性研究

In high-rise building fires, the most immediate threat to passengers’ life is not the direct exposure to fire but the smoke inhalation because it contains hot air and toxic gases, so it has positive meaning to research on efficient smoke control models. And now most research was focus on the development of fire and smoke in the building internal space. But from some fire accidents, we can find out that the smoke overflowed from the windows and spread to higher floors. So this project is concentrated on this special movement of smoke: fire room→outside→other floors. Theoretical model, numerical simulation and experiment result will be compared to reveal the critical characteristic and evolution of the smoke overflowing. . Reveal the interaction relationship of the overflow field of smoke with high temperature and the cold air supply field, and the influence mechanism of burning rate and temperature field changing with the height of the fire location; set up the critical mathematic model of the overflow smoke changing with the environment wind, which is associated with the burning rate, height of the fire room and the open condition (such as shape, size and so on). Set up the mathematic model of the entrainment strength, height of overflow and temperature distribution of the smoke, reveal the variation rule of overflow smoke at the axial and radial plane, put forward the multi function model by the action of the buoyancy and strong shearing force.Set up the critical couple model about the smoke parameters, overflow height and entrance condition when the smoke flows into the other floors; analysis the relationship model of the smoke parameters such as velocity, temperature and so on; the prediction model of smoke transportation will be put forward at the end.. This project could complete the key theory of the smoke transportation that from the fire room to the outside and then to the other floors and reveal the movement characters and rules of the overflow smoke. It will establish the theoretical and technological base of the smoke control system and evacuation..

目前，高层建筑火灾烟气研究主要集中在建筑内部和外壁面火灾，而本项目则主要针对高层建筑火灾烟气在风环境下由“着火房间→外部空间→其他楼层”的特殊临界外溢现象进行研究，揭示烟气外溢蔓延规律。. 研究风环境对不同高度着火房间内燃烧功率和温度场的影响机制，建立不同环境风下燃烧功率、火源高度、开口状态相关联的烟气溢出临界模型；研究不同高度环境风和溢流烟气耦合作用机制，建立溢流烟气高度、卷吸强度、温度等特征参数的关联模型，构建风环境下贴壁羽流和受迫羽流模型，揭示常规羽流和非常规羽流外部运动特性。研究风环境对不同高度溢流烟气的水平驱动机制，构建横向运动至其他楼层时烟气特征、溢出高度和入口条件相耦合的临界模型，分析此条件下烟气参数如速度、流量等，最后形成烟气运输预测方程。. 本研究可完善高层建筑火灾烟气运动理论，获得溢流烟气的特殊运动规律，为有效控制次生火灾和减少人员伤亡奠定理论基础。

针对高层建筑火灾时烟气由“室内→外部空间→室内”的特殊现象，对其不同风环境下烟气运动特性进行了分析研究，针对溢流的4大过程：受限空间火灾（环境风对室内燃烧的影响）→溢流行为（燃烧特性、环境风对烟气溢流临界条件的影响）→垂向扩散（环境风对外部烟羽流卷吸特性影响）→横行蔓延（环境风对烟羽流的水平驱动行为），探讨了溢流烟气运动行为。主要研究结果如下：研究了风环境下不同高度的受限空间开口处补气流场的影响机制，揭示了不同高度、风环境、开口条件下着火房间内的燃烧特性、温度场演变规律。研究了不同外部结构、燃烧功率和开口条件下，不同室外环境风对开口流场的影响，揭示了着火房间开口处（即窗户）烟气溢流的行为，获得烟气溢出的边界条件，获得了烟气溢出的燃烧功率、环境风参数、受限空间高度、开口条件相耦合的溢流特性。研究了开口处溢流烟气特征参数和燃烧功率、受限空间高度及开口条件的关系模型，揭示了溢流烟气轴向和径向温度分布随高度、风等参数的变化规律，获得了外壁面的温度分布规律；研究了不同环境风对溢流烟羽流作用效应，进而提出风环境作用下的分段羽流模型。研究了不同入口、室内压力等参数下，溢流烟气在不同高度受环境风水平驱动作用效应，揭示了烟羽流扩散至室内的烟气特征参数、溢出高度和入口条件相对应的特征参数；研究了环境风作用下烟羽流水平驱动扩散特性，得到了烟气在相应楼层至室内后运动扩散规律。本项目针对环境风高层建筑火灾烟气的溢流行为与扩散分布规律进行了研究，其研究结果对于建筑火灾防治和保障建筑内人员安全具有重要的研究意义和参考价值。