Comparison of a CFD Fire Model against a Ventilated Fire Experiment in an Enclosure
Comparison of a CFD Fire Model against a Ventilated Fire Experiment in an Enclosure
复制标题
CFD 火灾模型与外壳内通风火灾实验的比较
DOI：
10.1080/14733315.2004.11683912
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发表时间：
2004
影响因子：
1.5
通讯作者：
Y. Sinai
中科院分区：
文献类型：
--
作者：
Yunlong Liu;A. Moser;Y. Sinai
摘要计算机模拟火灾已成为一种有吸引力的方法，建议建筑结构的防火安全评估。为了设计和验证火灾模型，通用计算流体动力学（CFD）软件包，CFX，已被评估对火灾测试情况下，在通风房间。试验室长6.0 m，宽4.0 m，高4.5 m，出口为0.65 m x 0.65 m。一个简单的惰性火灾模型，其中一个恒定的体积热释放被引入在火源的位置来表示火灾。燃烧化学反应不包括在计算中;在本实验中，由于墙壁衬里是不可燃的，因此没有火焰蔓延和闪络到墙壁衬里材料。热量贡献仅来自燃烧器。结果表明，k- ε模型和剪应力输运（SST）混合湍流模型都能够预测火灾产生的湍流流动和传热。计算结果与劳伦斯利弗莫尔国家实验室（LLNL）的测量气体温度相比，误差约为20 °C，其中气体燃烧器的热量释放用于表示火灾。结果表明，在整个瞬态过程中，壁面的热能存款起着重要的作用。从数值的角度来看，外墙热边界条件处理对室内火灾的影响很小，因为在火灾开始后20分钟，在本实验情况下，热量仅渗透到20 cm厚的墙壁中约3 - 4 cm。已分析了能量预算，以了解该火灾测试用例的能量转移。根据这个测试，大约30%的热量从火灾中释放出来的热辐射，约30%是由通风空气在点燃后的前20分钟内带出房间，其余的是沉积在墙壁，天花板和地板上。可以得出结论，这种CFD方法可以作为一种工具，在封闭的火灾产生的热传递建模。热辐射在火灾传热过程中起着重要作用。结果表明，为了准确地模拟火灾过程，必须在火灾数学模型中考虑共轭传热。
Abstract Computer modelling of fire has become an attractive approach for the fire safety assessment of proposed building structures. To devise and validate the fire model, a general–purpose computational fluid dynamics (CFD) software package, CFX, has been evaluated against a fire test case in a ventilated room. The test room is 6.0 m long, 4.0 m wide and 4.5 m high with an exit opening of 0.65 m x 0.65 m. A simple inert fire model is used, in which a constant volumetric heat release is introduced at the location of the fire source to represent the fire. Combustion chemical reactions are not included in the computation; there was no flame spread and flashover to the wall lining material in this experiment, as the wall lining was non–combustible. The heat contribution is solely from the burner. It was demonstrated that both the k– ε model and the Shear Stress Transport (SST) hybrid turbulence model are capable of predicting the fire–generated turbulent flow and heat transfer. The computational result has an error of about 20 °C when compared with the measured gas temperature of the Lawrence Livermore National Laboratory (LLNL), in which the heat release from a gas burner is used to represent a fire. It has been confirmed that the thermal energy deposit into the wall plays a significant role in the whole transient process. From the numerical point of view, the exterior wall thermal boundary condition treatment has little influence on the fire inside the room, as at 20 minutes after the start of the fire, heat penetrates only about 3 – 4 centimetres into the 20–cm–thick wall in this experimental case. The energy budget has been analysed to understand the energy transfer for this fire test case. According to this test, about 30 percent of the heat from the fire is released by thermal radiation, and about 30 percent is carried out of the room by the ventilation air over the first 20 minutes after ignition, the rest is deposited into the walls, ceiling, and the floor. It can be concluded that this CFD approach can serve as a tool for the modelling of fire generated heat transfer in an enclosure. Thermal radiation plays an important role in the heat transfer process from the fire. It has been concluded that, in order to accurately simulate a fire case, the conjugate heat transfer must be included in the fire mathematical model.