低压下典型可燃液体层流扩散火焰及碳烟分布规律研究

发布时间：2018-06-12 02:41

本文选题：碳烟 + 低压　；参考：《中国科学技术大学》2017年硕士论文

【摘要】：高原、高空等低压低氧环境下的火灾防控一直以来是社会关注的热点问题。碳烟是含碳可燃物未完全燃烧的产物,是观察可燃物燃烧行为的重要参数。研究低压低氧条件下的碳烟分布规律,对进一步深入研究高原、高空环境下燃烧行为特征和火灾防控方法具有重大意义。本文主要研究了几种典型可燃液体在低压下的层流扩散火焰形态特征及碳烟浓度分布规律。利用内径为240 mm、高度为600 mm,可调压力范围为40～1O1kPa的低压燃烧实验舱及酒精灯式燃烧器,分别对8种可燃液体样品在7个低压工况下(40、50、60、70、80、90和101 kPa)进行了燃烧实验,样品包括3种纯净物(正己烷、正庚烷和正辛烷)、3种混合物(纯净物按质量配比)和2种商用燃料(汽油和航空煤油)。定量分析了三种可燃液体纯净物在40～101 kPa压力范围内的火焰高度、宽度及其与压力的关系,发现其火焰高度均随压力升高而增加,火焰宽度随压力增加而减小,含碳量越高,火焰宽度随压力的变化越慢。利用激光诱导炽光法研究了 8种实验样品在低压条件下火焰碳烟浓度分布规律与压力变化的关系,结果表明对同一可燃液体,压力越高,碳烟浓度越大;在同一压力下,可燃物含碳量越高,碳烟浓度越大。从火焰根部到顶部,碳烟浓度的集中分布位置分为两个阶段:从火焰根部到某一临界高度,碳烟集中分布在以火焰中轴线为中心的环形区域内;从临界高度到火焰顶部,碳烟集中分布在火焰中轴线上。通过对本实验中整个火焰的碳烟浓度峰值进行半定量分析,并与其他学者的实验结论进行比较,得到规律:该峰值与压力成指数关系,可燃物含碳量越高,指数越小。
[Abstract]:Fire prevention and control in plateau, high altitude and other low-pressure and low-oxygen environment has always been a hot issue of social concern. Soot is the product of incomplete combustion of carbonaceous combustibles and an important parameter to observe the combustion behavior of combustible substances. The study of soot distribution under low pressure and low oxygen condition is of great significance for further study of combustion behavior characteristics and fire prevention and control methods in plateau and high altitude environment. The characteristics of laminar diffusion flame and the distribution of soot concentration of several typical combustible liquids under low pressure are studied in this paper. The combustion experiments of 8 kinds of combustible liquid samples under 7 low pressure conditions were carried out by using a low-pressure combustion chamber with an internal diameter of 240 mm, a height of 600 mm and an adjustable pressure range of 401O1kPa and a wine lamp burner. The combustion experiments were carried out under 7 low pressure conditions, respectively. The sample consists of three pure compounds (n-hexane, n-heptane and n-octane) and two commercial fuels (gasoline and aviation kerosene). The flame height, width and the relationship between the flame height and pressure of three kinds of pure combustible liquid in the pressure range of 40 ~ 101kPa are quantitatively analyzed. It is found that the flame height increases with the increase of pressure, the flame width decreases with the increase of pressure, and the carbon content increases. The flame width changes slowly with the pressure. The relationship between the distribution of flame soot concentration and the pressure change of eight experimental samples at low pressure was studied by laser induced incandescent light method. The results show that the higher the pressure is, the greater the soot concentration is for the same flammable liquid, and the higher the pressure is, the higher the soot concentration is at the same pressure. The higher the carbon content of combustible matter, the higher the soot concentration. From the root of the flame to the top, the distribution of soot concentration is divided into two stages: from the root of the flame to a certain critical height, the soot is concentrated in a circular region centered on the central axis of the flame, and from the critical height to the top of the flame, Soot is concentrated on the central axis of the flame. Through the semi-quantitative analysis of the peak of soot concentration of the whole flame in this experiment, and compared with the experimental results of other scholars, the law is obtained: the peak value is exponentially related to the pressure, the higher the carbon content of the combustible matter, the smaller the index.
【学位授予单位】：中国科学技术大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：X932

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