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Understanding and Modeling of Backdraft Phenomena Occurred in Fires of Highly Insulated and Air-Tightened Houses

高隔热气密房屋火灾中发生的逆燃现象的理解和建模

基本信息

批准号：
09650643
负责人：
HAYASAKA Hiroshi
金额：
$ 1.02万
依托单位：
HOKKAIDO UNIVERSITY
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

This research is carried out to understand backdraft phenomena in fires. Backdraft phenomena was observed experimentally, Experiments were carried out in a 0.85 m high, 0.82 m wide, 1.05 m long compartment by using actual wood. The mass pyrolysis rate of actual wood, and O_2, CO_2, CO and THC (Total Hydrocarbons) in the upper and lower layers in the compartment were measured. Precise temperature distribution maps were made. Backdraft and its related phenomena caused by pyrolyzates from wood were observed through the side wall made of a newly developed refractory glass. The results obtained from experiments in a one third scale compartment under highly insulated and low-ventilation conditions may allow the following conclusions : l. After the fire had consumed almost all the oxygen in the upper layer, the flame lost its activeness and a drifting or ghosting flame occurred. The flame moved slowly between the rear wall and the opening. 2. Suddenly, the flame at the opening disappeared. It self-extinguished. 3. Just after the self-extinguishment of the fire, there were no visible flames in the compartment but a constant mass pyrolysis rate was observed. Smoldering of the wood became main reaction. A relatively long, about ten minutes, smoldering period was observed before a first backdraft occurred. 4. After the first backdraft, a persistent flame was formed near the opening and lasted about three minutes. This kind of flame might killed firefighters in the reported backdraft fires. 5. The observed backdraft flame started from near the ceiling and then rapidly spread to the floor and the opening. 6. Second and third smoldering period were observed before second and third backdraft occurred. But their period became very short, forty and nineteen seconds respectively. 7. Spontaneous ignition of wood may play an important role in an occurrence of backdraft in our experiments.

本研究旨在了解火灾中的回风现象。实验采用实木在高0.85 m、宽0.82 m、长1.05 m的舱室中进行。测量了实际木材的质量热解速率，以及舱内上下两层的O_2、CO_2、CO和THC（总烃）。绘制了精确的温度分布图。通过新研制的耐火玻璃侧壁，观察了木材热解产物引起的回风及其相关现象。在高度绝缘和低通风条件下，在三分之一尺度的隔间中进行的实验结果可以得出以下结论：1 .当火焰消耗了上层几乎所有的氧气后，火焰失去了活性，出现了飘移或鬼隐的火焰。火焰在后墙和洞口之间缓慢移动。2. 突然，洞口的火焰消失了。它自熄。3. 火灾自熄后，隔室内未见明显火焰，但观察到质量热解速率恒定。木材闷烧成为主要反应。在第一次回流发生之前，观察到一个相对较长的，大约10分钟的阴燃期。4. 在第一次回流后，在洞口附近形成了一个持续的火焰，持续了大约三分钟。这种火焰可能会在报告的逆气流火灾中杀死消防员。5. 观察到的回风火焰从天花板附近开始，然后迅速蔓延到地板和开口。6. 在第二次和第三次回流发生之前，观察到第二次和第三次阴燃期。但是他们的时间变得很短，分别是40秒和19秒。7. 在我们的实验中，木材的自燃可能对回风的发生起着重要的作用。