庚烷池火多火源燃烧特性的实验研究

Experimental study on combustion characteristics of multiple heptane pool fires

多火源燃烧是森林火灾和城市群发性火灾中重要而又特殊的火灾现象,相关研究很少。通过恒定控制液面高度的实验系统,对直径0.1m、0.2m和0.4m的庚烷池火在单个火源、两火源燃烧和三火源线性排列时的火焰高度、火焰体积和燃烧速率等特性进行了实验研究。研究发现,三火源燃烧时中间火源的火焰高度、火焰体积和燃烧速率明显高于两火源燃烧和单火源燃烧,三火源燃烧时边上火源与两火源的燃烧状况难以区分。这些燃烧特性随着火源间距的减小,呈现增大趋势。热量反馈增强和空气卷吸受限这两种火源相互作用机制相互耦合,且随着火源间距的减小而增强,在S/D(S为火源间距,D为油池直径)为2～4时,两种机制强烈竞争,在其他参数范围内热量反馈增强效应占主导作用。研究还发现火焰体积与热释放速率有较好的线性相关关系,单位火焰体积的热释放速率约为1614kW/m3。

Multiple fires burning is typical in forest and urban fires. In this work, burning of multiple heptane pool fires was investigated by experiments, in which the height of fuel surface was kept constant. The flame height, flame volume and burning rate for single fire, two fires and three fires of heptane pools being in line were studied experimentally. Pool diameters of 0. lm, 0. 2m and 0.4m were used in the experiments. It was found that the flame height, flame volume and burning rate of the central fire in three fires burning were larger than those in burning of two fires and single fire. The flame height, flame volume and burning rate increased gradually with decreasing fire spacing. It was also found that the interaction mechanisms vary with fire spacing. Heat transfer enhancement is the dominant effect when S/D （where S is the fire spacing, and D is the pool diameter） is larger than 4 and smaller than 2. When S/D is 2-4, heat transfer enhancement and air entrainment limitation compete with each other. The volumetric heat release rate was found to be nearly a constant of 1614kW/m3.