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Experimental Study on Variety Modes of Smoke Movement on Fire

火灾时烟气多种运动方式的实验研究

基本信息

批准号：
09650652
负责人：
NITTA Katsumichi
金额：
$ 1.02万
依托单位：
Kyoto Institute of Technology
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1997
资助国家：
日本
起止时间：
1997 至 1998
项目状态：
已结题

项目摘要

It's a subject of discussion that the smoke flows in rooms, corridors or vertical shafts generated by fire should not be contrary to our expectations from the safety viewpoint of the human evacuation. The assessment of the existence of variety modes for the directions of smoke flows must be required in its early stage of the disaster prevention planning.In our research, the verifications of the variety modes latent in the building ventilation system or the smoke vent system were done by both the approach of the analytical and experimental studies.In our analytical study, it is shown that the governing fundamental equations of the ventilation (or smoke vent) system are non-linear, and the variety modes are caused by the variable buoyancy terms for the case of the unknown variable Cs), namely known heat supply rate (s). The concrete examples of the ventilation variety are shown by the numerical calculation results for the two or three story building, From the investigation for the related physical parameters, we could indicate that the wind speed have the most impact on the variety modes. In connection with the prediction in the occurrence frequency of a specified ventilation mode, we showed for the first time that the 'CHAOS' is possessed in the building ventilation and the flow patterns result in another mode with slightly different initial conditions of numerical calculation.In our experimental work, we get the verifications of the ventilation variety by means of the model tests on the scales of 41100 and 61100. Two modes of ventilation were confirmed for the models of symmetrical three story buildings, though the five modes were admitted in the numerical calculation for the same conditions with the models. By the visualization test with liquid paraffin mist, the cause of the difference in the variety occurrence between the analysis and experiment.

从人员疏散的安全角度考虑，火灾产生的烟气在房间、走廊或竖井中的流动不应违背我们的期望，这是一个讨论的主题。在防灾规划的早期阶段，必须评估烟气流动方向的各种模式的存在。本研究通过分析和实验研究两种方法，对建筑通风系统或排烟系统中潜在的各种模式进行了验证。在分析研究中，结果表明，通风（排烟）系统的基本方程是非线性的，在未知变量Cs（即已知供热率s）的情况下，变化的模态是由浮力项引起的。通过对二、三层建筑物的数值计算结果，给出了通风变化的具体实例。通过对相关物理参数的考察，可以看出风速对变化模态的影响最大。针对特定通风模式发生频率的预测，我们首次证明了建筑通风中存在“混乱”现象，并且流动模式导致了另一种模式，但数值计算的初始条件略有不同。在我们的实验工作中，通过41100和61100缩尺的模型试验，验证了通风量的变化。对于对称的三层建筑模型，虽然在相同条件下的数值计算中承认了五种通风模式，但确定了两种通风模式。通过液体石蜡雾的可视化试验，分析了与试验结果差异的原因。