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翁丁村是我国典型的杆栏式古建筑群,为防止火灾在建筑间蔓延,当地传统风俗中形成了在发生火灾时拆除建筑茅草顶的防火技法。为验证这种防火技法的有效性并为后期试验提供理论依据,采用火灾动力学模拟软件FDS对典型民居进行了火灾动力学分析,获得了不同屋顶拆除时间火灾场景下的火灾热释放速率、热辐射通量和建筑间安全距离。在此基础上,结合理论分析给出了拆除屋顶的临界时间的理论计算公式,并比较了两种不同热辐射简化计算模型的计算效果。结果表明:在临界时间之前,即建筑火灾由燃料控制型转变为通风控制型之前拆除屋顶,可有效降低火灾发生时的热释放速率和热辐射强度,从而能有效地防止建筑间的火灾蔓延;由于房屋间距小,在临界时间之后才拆除起火建筑的屋顶,会导致火灾在建筑间蔓延;采用面源简化计算模型计算不同距离的热辐射通量,与计算机模拟的结果更为接近。
Onding village is a typical bar-type ancient buildings in our country. In order to prevent the spread of fire among buildings, the local traditional customs form a fire-proof technique for demolishing thatched roof in the event of a fire. In order to verify the effectiveness of fire prevention techniques and provide a theoretical basis for the later experiments, the fire dynamics simulation software FDS was used to analyze the fire dynamics of typical residential buildings, and the fire release rate under different scenes of roof fire was obtained. Radiation flux and safety distance between buildings. On this basis, theoretical calculation formula of the critical time for roof removal is given in combination with theoretical analysis, and the computational effects of two different radiative simplification calculation models are compared. The results show that it is effective to prevent the fire spread between buildings before the critical time, that is, the building fire is removed from the fuel control type to the ventilation control type, and the heat release rate and heat radiation intensity can be effectively reduced. Due to the small house spacing, it is not possible to remove the roof of a fire building after the critical time, which will result in the fire spreading among the buildings. Using the simplified model of surface source to calculate the heat radiation fluxes at different distances is closer to the result of computer simulation.