基于混合式通风的中庭建筑火灾烟气控制研究

发布时间：2018-02-23 22:43

  本文关键词： 火灾烟气 FDS模拟 缩尺模型实验 混合通风　出处：《南京工业大学》2015年硕士论文　论文类型：学位论文

【摘要】：随着我国经济的发展,中庭建筑不断增多,火灾成了中庭建筑最大的安全隐患。火灾发生时,烟气的高温、毒性和窒息是造成人员伤亡的主要原因,因此需对流动的烟气进行控制,设置防排烟系统阻止烟气下降至中庭底部,保障人员的安全疏散。本文系统地分析了中庭建筑内烟气控制方式的研究现状,利用两层区域模型的思想建立中庭火灾烟气流动数学模型,并采用火灾动力学模拟软件(FDS,Fire Dynamics Simulator)以及1/10缩尺火灾实验进行研究,针对中庭建筑火灾烟气流动特点,提出自然排烟+机械送风的混合通风方式来改善中庭火灾时的室内烟气环境。本文以两层区域模型为基础,分别建立了中庭火灾时烟气自然填充、自然排烟过程的数学模型。为之后的实验以及数值模拟研究提供了理论研究基础。本文开展建筑中庭火灾时利用顶部开口自然排烟,结合中上部机械侧送风防止烟气下沉的可行性研究。搭建了1/10的缩尺模型中庭,顶部开口,多组送风口设置于双侧墙中上部,进行多工况下的温度、风速与烟气沉降的测试。首先利用羽流模型推导出的经验公式验证了1/10中庭模型试验的可行性,并用模型实验的数据与FDS全尺寸数值模拟结果作对比,验证FDS全尺寸数值模型的正确性。试验与模拟结果均表明自然填充条件下,烟气温升最大；机械排烟条件下,烟气分层被打乱,烟层下降最快；项部开口起到良好的自然排烟作用,但烟层下降仍很明显;自然排烟与机械送风结合的模式下,当送风速度达到1.3m/s、每侧射程达到送风方向中庭尺寸的3/7、风机开启时间30s时,烟气层高度始终维持在0.4m以上,保障了地面人员的安全疏散。本文基于大涡模拟法理论,采用场模拟数值方法FDS,模拟中庭建筑内火灾烟气扩散。对机械送风+自然排烟的防排烟模式作进一步的研究,提出用送风气幕取代多风口送风的思想,建立送风气幕、中庭以及火源相关参数之间的定量关系,得出当送风气幕的吹口高度与中庭高度的比值为0.66、吹口宽度与长度之比为0.01、吹口速度为2.8m/s、风机开启时间为60s、中庭开口率为0.084、形状系数越大达到3.06、室温越小为10℃、火源热释放速率越小为1.5MW、火源位置位于墙角燃烧受限时,这时的排烟效果是最佳的。
[Abstract]:With the development of economy in China, the number of atrium buildings is increasing, and fire has become the biggest safety hazard in atrium buildings. When the fire occurs, the high temperature, toxicity and suffocation of smoke are the main causes of casualties. Therefore, it is necessary to control the flow of flue gas, set up a smoke control system to prevent the smoke from falling to the bottom of the atrium, so as to ensure the safe evacuation of personnel. The mathematical model of smoke flow in atrium fire is established by using the idea of two-layer region model. The fire dynamic simulation software (FDS Fire Dynamics Simulator) and the 1/10 scale fire experiment are used to study the characteristics of smoke flow in atrium fire. In this paper, the mixed ventilation method of natural smoke exhausting machine is put forward to improve the indoor smoke environment during atrium fire. Based on the two-layer regional model, the natural filling of smoke during atrium fire is established in this paper. The mathematical model of the natural smoke exhaust process provides a theoretical basis for the subsequent experiments and numerical simulation studies. In this paper, the roof openings are used to naturally exhaust smoke during the building atrium fire. Combined with the feasibility study of mechanical side air supply to prevent smoke from sinking in the middle and upper part of the wall, a 1/10 scale model of atrium, top opening, multiple sets of tuyere is set up in the middle and upper part of the wall, and the temperature under multiple working conditions is carried out. The feasibility of the 1/10 atrium model test is verified by the empirical formula derived from the plume model, and the data of the model experiment are compared with the FDS full-scale numerical simulation results. The experimental and simulation results show that the temperature rise of flue gas is the largest under natural filling condition, and the stratification of smoke layer is disturbed and the smoke layer decreases fastest under mechanical exhaust condition. The opening of the item plays a good role in the natural exhaust of smoke, but the decrease of the smoke layer is still very obvious. When the speed of air supply reaches 1.3 m / s, the range of each side reaches 3 / 7 of the atrium size in the direction of air supply, and the opening time of the fan is 30s, in the combined mode of natural smoke exhaust and mechanical air supply, The height of flue gas layer is always above 0.4 m, which ensures the safe evacuation of ground personnel. This paper is based on the theory of large eddy simulation. The field simulation numerical method FDS is used to simulate the smoke diffusion of fire in the atrium building. The smoke prevention and exhaust mode of natural exhaust smoke from mechanical air supply is further studied, and the idea of replacing multiple air outlets with air supply curtain is put forward, and the air supply curtain is established. The quantitative relationship between atrium and fire related parameters, The results show that when the ratio of blowing height to atrium height is 0.66, the ratio of blowing width to length is 0.01, the blowing speed is 2.8 m / s, the opening time of fan is 60 s, the opening ratio of atrium is 0.084, the shape coefficient is 3.06, and the room temperature is 10 鈩，

本文编号：1527917