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

这项研究是为了了解火灾中的回燃现象。在高0.82m、宽0.82m、长1.05m的隔室中，用实木进行了回拔实验。测定了实际木材的质量热解速率以及小室上层和下层的O2、CO2、CO和THC(总碳氢化合物)。绘制了精确的温度分布图。通过一种新研制的耐火玻璃的侧壁，观察到了木材热解产物引起的回燃及其相关现象。在三分之一的隔热和低通风条件下的实验结果可以得出以下结论：L。火灾几乎消耗了上层所有的氧气后，火焰失去了活性，出现了漂移或鬼火。火焰在后墙和洞口之间缓慢移动。2.突然，开口处的火焰消失了。它自我熄灭了。3.火灾自行熄灭后，室内没有可见的火焰，但观察到了恒定的质量热解速率。木材的阴燃成为主要反应。在第一次回流发生之前，观察到了一个相对较长的、大约10分钟的阴燃时期。4.在第一次回流后，在开口处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道的逆风火灾中杀死消防员。5.观测到的回流火焰从天花板附近开始，然后迅速蔓延到地板和洞口。6.在第二次和第三次回燃之前，观察到了第二次和第三次阴燃。但他们的周期变得非常短，分别为40秒和19秒。7.在我们的实验中，木材的自燃可能在回燃的发生中起着重要作用。

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.