火前锋附壁的模拟实验研究

Experimental simulation study on flame attachment in fire spread

设计了可变坡度燃烧实验台,利用气体燃烧器模拟沟槽地形火蔓延中的火前锋。以丙烷为燃料,主要开展了不同坡度和高宽比(挡板高度与燃烧器宽度之比)条件下的气体燃烧实验。结果表明,坡度是影响火焰附壁的关键因素,挡板的存在限制了侧向卷吸从而加快火焰倾斜甚至附着。上坡火前锋存在一个发生火焰部分附着的临界坡度,该临界坡度不随挡板高宽比的变化而改变,该文的临界坡度为10°~15°。随坡度继续升高,高于另一临界坡度时,火焰完全附着在实验台面上,形成薄片状结构,发生火焰完全附着。附着火焰表现出明显的脉动性,随坡度的增大而增强,挡板的存在明显加剧了火焰脉动,而高宽比的变化对火焰脉动特性无显著影响。

A gas fire test bench was designed with adjustable slope in this paper,to simulate the flame front in trench fire spread.With propane as the fuels,gas burner experiments under different slopes and aspect ratios(ratio of height of side wall to burner width)were carried out.The results show that slope is the key factor causing flame attachment,while the effect of side wall is just to restrict air entrainment and accelerate the rate of flame tilting.There is a critical slope at which flame partially attaches,and this critical slope is not significantly affected by the aspect ratio.The critical slope of this paper is 10°~15°.As the slope continues to rise above another critical slope,the flame attaches completely to the bench surface,forming a“sheet”structure.The attached flame shows obvious pulsation which is enhanced with the increasing slope.The presence of side wall can significantly affect the pulsation characteristics of the flame,while the aspect ratio does not have a significant effect.