水喷淋对典型建筑外饰材料竖直火蔓延抑制机制研究

发布时间：2018-02-25 20:13

本文关键词： 高层建筑火灾向上火蔓延固体材料燃烧水喷淋灭火技术　出处：《中国科学技术大学》2015年博士论文　论文类型：学位论文

【摘要】：近年来,高层建筑火灾已成为危害城市居民人身和财产安全的重大灾害之一。高层建筑火灾中,建筑本身的结构特性导致其火灾立体蔓延特性。建筑立体火蔓延一般可分为向上火蔓延、侧向火蔓延以及向下火蔓延。其中,向上火蔓延是三种形式中最快速和严重的一类蔓延类型,在火灾安全研究中一直备受重视。研究其蔓延规律以及发展相应的火灾防治技术,是当前亟待解决的新问题。水喷淋是抑制建筑外立面火灾的有效手段之一,而高层建筑贮水有限且高层灭火供水困难,探索水喷淋抑制外立面火蔓延及灭火机理对建筑外墙水喷淋灭火系统研究具有重要意义。本文旨在通过对竖直壁面上可燃材料的点燃、燃烧及火蔓延基本行为特征进行实验研究,揭示竖直壁面火蔓延的基本规律,为喷淋灭火技术的提出及施加方式提供参考依据；在此基础上,设计适用于竖直壁面燃烧及火蔓延场景的水喷淋系统,实验研究不同喷淋条件下喷淋灭火有效性及其影响规律,为发展实际可行的喷淋系统和优化喷淋参数提供指导。具体的研究工作如下：竖直壁面可燃材料燃烧及火蔓延规律研究。通过对可燃物的点燃、燃烧及火蔓延过程进行理论分析,建立点燃时间与外界加热强度的理论模型,并对理论模型进行实验验证。燃烧及火蔓延方面,从传统火蔓延基本理论出发,分析平均火焰高度与热释放速率关系,讨论火蔓延过程中平均火焰高度与平均热解前锋高度的理论关系,对热解前锋高度位置随时间变化的理论模型精确解进行分析,最后进行实验验证。水喷淋抑制竖直壁面可燃材料燃烧及火蔓延规律研究。设计适用于所述燃烧及火蔓延场景的水喷淋系统并用于喷淋灭火实验研究,主要包括不同喷淋施加角度、喷淋压力/流量等条件对灭火行为的影响。结果显示对于燃烧的抑制过程,喷淋液滴对竖直壁面可燃物燃烧表面的冷却作用是喷淋抑制固体材料热解和燃烧的主要机理,喷淋施加角度会影响喷淋液滴与燃烧表面的“有效作用面积”,导致燃料熄灭时间随喷淋施加角度的增加而减小。对于较大高宽比的火蔓延过程,喷淋抑制火蔓延主要靠喷淋液滴在燃烧表面形成的水成膜以及液膜在壁面上的流动换热来实现。实验结果显示,喷淋水成膜灭火时间随喷淋流量的增加而减小。另外,为对实验研究进行补充并验证实验结果,采用数值计算方法对竖直火蔓延及喷淋灭火过程进行研究。获取火蔓延过程中竖直壁面表面温度、火焰高度、热解高度等变化规律并与实验结果进行对比,研究水喷淋对竖直壁面可燃材料点燃及火蔓延的影响规律,获取喷淋抑制竖直壁面可燃材料燃烧的临界流量等。建筑外墙立面水喷淋灭火系统研究。依据理论分析和实验研究结果,提出一种可以用于建筑竖直外墙立面灭火的喷淋系统设计方案。通过实验研究分析了水幕喷淋的基本特性以及水流在建筑外墙竖直壁面上的流动情况。为改善水幕喷头能量损失较明显的问题,提出一种新型离心导流式消防水幕喷头设计方案。在此基础上,设计可用于建筑外墙立面灭火的水喷淋系统并定量分析其可行性。
[Abstract]:In recent years, the high-rise building fire hazard has become one of the major city residents personal and property safety. The high-rise building fire, the structure characteristics of the building itself caused the fire. The fire spread characteristic stereo stereo spread to the building can be divided into the fire spread, fire spread and fire spread down the side. The fire spread is to three kinds of the most rapid and severe type spread type, has always been of great importance in the fire safety research. Study the spread rules and the development of corresponding fire prevention and control technology, is a new problem to be solved. The water spray is one of the effective means to restrain the facade of the building fire, high-rise buildings and high-rise water storage Co. fire water supply difficulties, explore the water spray suppression facade fire spread and fire extinguishing mechanism has important significance for building exterior wall water sprinkler system.
This paper aims to light on the vertical wall surface of combustible materials, combustion and fire spread the basic behavioral characteristics of the experimental research, reveals the basic law of vertical wall fire spread, is proposed to provide reference for the sprinkler and applied technology; on this basis, the design of water spray system for vertical wall burning and spreading scene experimental study on the fire, under the condition of different spray sprinkler effectiveness and influence, to provide guidance for the development of practical sprinkler system and optimization of spray parameters. The specific studies are as follows:
The law of spread of the vertical wall surface burning of combustible materials and fire. Through the burning of the fuel, combustion and fire spread process of theoretical analysis, establish theoretical model of ignition time with an external heat intensity, and experiments are carried out to verify the theoretical model. The spread of burning and fire, the fire spread from the traditional basic theory, analysis of the average flame the height and heat release rate of fire spread process, discuss the theory of the relationship between the average flame height and average height of pyrolysis front, exact solutions of the theoretical model of the height of pyrolysis front changes with time are analyzed, finally verified by the experiment.
The spread of the law study on inhibition of vertical wall surface burning of combustible materials and fire water spray is designed. Water spray system in the combustion and fire scene and experimental study for sprinkler, including applying different spray angle, spray impact pressure / flow conditions on fire behavior. The results show that for the inhibition of the combustion process, spray the droplet on the vertical wall surface combustible surface cooling effect is the main mechanism of spray pyrolysis and combustion inhibition of solid materials, the spray applied angle will affect the spray droplet and the combustion surface of the "effective area", resulting in the increase of fuel spray quenching time with the applied angle decreases. For the large aspect ratio of the fire spread the process of spraying, inhibition of fire spread mainly by spraying liquid droplets in the aqueous film formed on the surface of the combustion and the film on the wall of the flow and heat transfer is achieved. Experimental results show that, Spray AFFF extinguishing time decreases with increasing flow rate. In addition, as a complement to experimental research and experimental results, by using the numerical method to study the vertical spread and spray fire extinguishing process. The vertical wall for fire spread process of surface temperature, flame height, height variation of pyrolysis and compared with the experimental results, Research on the influence of light vertical surface of combustible materials and fire spread the water spray, spray for suppressing combustion vertical surface of combustible materials critical flow.
Building facade water sprinkler system research. According to the results of theoretical analysis and experimental research, put forward a kind of can be used for building facade design of vertical fire sprinkler system. Through the experimental study of flow characteristics of water spray and water flow in the vertical wall on the wall. In order to improve the energy loss of a water curtain nozzle the obvious problem, puts forward a new type of centrifugal type fire water curtain nozzle design. Based on the quantitative analysis of the feasibility of the water spray system and design can be used for building exterior facade of the fire.

【学位授予单位】：中国科学技术大学
【学位级别】：博士
【学位授予年份】：2015
【分类号】：TU564;TU998.1

【参考文献】