典型热薄型材料竖向逆流火蔓延行为研究

发布时间：2018-06-20 13:01

本文选题：PMMA + 棉布　；参考：《中国矿业大学》2017年硕士论文

【摘要】：随着时代的发展,大体量、多功能的公共建筑层出不穷。建筑内使用的可燃、易燃材料的数量和种类都迅速增加,建筑内装饰装修用的材料多为薄型可燃易燃材料,如有机玻璃、装饰帘布、悬挂广告布、壁纸等。这些薄型材料可以分为两类:非碳化和碳化材料。这些易燃的薄型材料,一旦接触到火源或高温炽热物体就会迅速燃烧,极易引燃相邻的可燃物,造成大面积的火灾。而目前国内外对薄型材料的研究多基于某种尺寸材料的竖向顺流火蔓延,以及对墙面贴壁火或两面临空的火蔓延研究。对于不同受限距离以及和宽度耦合作用下的竖向逆流火蔓延缺乏相应的理论和实验研究。本文设计了非碳化薄型材料PMMA和碳化薄型材料棉布两种类型的竖向逆流火蔓延实验。实验设置了4种受限距离,分别为7 mm、13 mm、19 mm和25mm,同时设置了3种宽度,分别为50 mm、100 mm和150 mm。在此基础上展开了24组72次逆流火蔓延实验,探究了薄型材料PMMA和棉布在不同受限距离和不同宽度条件下竖向逆流火蔓延特性。主要研究火焰前沿、火焰高度Hf、热解前锋xp、火蔓延速率vp、燃尽前锋xb和热解长度Lp等火蔓延特性参数。实验发现,非碳化材料PMMA的火焰形状为锯齿形,且受限距离为13 mm时的火焰前沿角变化幅度最大,而宽度为150 mm时火焰前沿角变化幅度最大。棉布的火焰形状为矩形,宽度为50 mm时,火焰前沿角变化幅度和100 mm接近;受限距离为13 mm时火焰前沿角变化幅度最小,7 mm时变化幅度最大。对于PMMA,当宽度相同时,受限距离的临界值为13 mm,且该临界值时各特性参数最大,7 mm时特性参数最小,总体表现为随着受限距离的增大,各特性参数先增大后减小。当受限距离相同时,热解前锋、燃尽前锋和火蔓延速率随着宽度的增加而增大,且都近似幂函数的增长模式,其通式分别为x_i=a_i+b_i·t~c_i，v_j=a_i·t~b_i。火焰高度和热解长度表现为宽度为150 mm时最大,100 mm时最小,无量纲火焰高度50 mm时最大,100 mm时最小。对于棉布,当宽度相同时,受限距离的临界值为13 mm,且该临界值时各特性参数最小,7 mm时特性参数最大,总体表现为随着受限距离的增大,各特性参数先减小后增大。当受限距离相同时,热解前锋、燃尽前锋和火蔓延速率随着宽度的增加而增大,呈现一次函数增长模式,其通式分别为x_j=a_j+b_j·t，，v_j=a_j+b_j·t。无量纲火焰高度和热解长度随着宽度的增大而减小。
[Abstract]:With the development of the times, large-volume, multi-functional public buildings emerge in endlessly. The number and types of combustible materials used in buildings are increasing rapidly. The materials used for decoration and decoration are mostly thin flammable materials, such as organic glass, decorative curtains, hanging advertising cloth, wallpaper and so on. These thin materials can be divided into two categories: non-carbonized and carbonated materials. These flammable thin materials will burn quickly once they come into contact with the source of fire or hot objects at high temperature, which can easily ignite the adjacent combustible materials, resulting in a large area of fire. At present, most of the researches on thin materials are based on vertical downstream fire spread of certain size materials, and on wall fire or fire spread on both sides. There are few theoretical and experimental studies on the vertical countercurrent spread under the coupling of different limited distances and widths. In this paper, the vertical countercurrent fire propagation experiments of PMMA and cotton cloth with non-carbonized thin materials are designed. Four kinds of limited distances (7 mm / 13 mm / 19 mm and 25 mm) and three widths of 50 mm / 100 mm and 150 mm / m were set respectively. On this basis, 24 groups of 72 times countercurrent fire propagation experiments were carried out, and the vertical countercurrent fire propagation characteristics of thin PMMA and cotton cloth were investigated under different limited distances and different widths. The flame front, the flame height HF, the pyrolysis front xp, the fire spread rate VP, the burnout front xb and the pyrolysis length LP are studied. The experimental results show that the flame shape of PMMA is serrated, and the flame front angle of PMMA is the largest when the confined distance is 13 mm, and the flame front angle is the biggest when the width is 150 mm. The flame angle of cotton cloth is rectangular, and when the width is 50 mm, the change amplitude of the flame front angle is close to 100 mm, while the change amplitude of the flame front angle is the biggest when the limiting distance is 13 mm. For PMMAs, when the width is the same, the critical value of the restricted distance is 13 mm, and the critical value of each characteristic parameter is the minimum at the maximum value of 7 mm. The overall performance is that with the increase of the limited distance, the characteristic parameters increase first and then decrease. When the limited distance is the same, the pyrolysis forward, the burnout forward and the fire spread rate increase with the increase of the width, and are similar to the growth mode of the power function. The flame height and pyrolysis length are the minimum when the width is 150 mm and the maximum is 100 mm when the dimensionless flame height is 50 mm. For cotton cloth, when the width is the same, the critical value of limited distance is 13 mm, and the maximum characteristic parameter is at the minimum of 7 mm at this critical value. The overall performance is that with the increase of the limited distance, the characteristic parameters decrease first and then increase. When the limited distance is the same, the pyrolysis front, the burnout forward and the fire spread rate increase with the increase of the width, and the primary function growth mode is presented. The dimensionless flame height and pyrolysis length decrease with the increase of width.
【学位授予单位】：中国矿业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TU502

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