摘要
采用纹影系统、压力传感器和高速相机对甲烷-空气预混气体在定容燃烧弹中的燃烧特性进行研究,分析了当量比对拉伸火焰传播速度、未拉伸火焰传播速度和层流燃烧速度的影响及定容弹中压力的变化规律。结果表明,当量比对预混气体燃烧过程有重要影响,且存在临界当量比1.1,在临界当量比下预混气体燃烧最剧烈,层流燃烧速度达到最大值(0.368 m/s),燃烧压力也达到峰值(0.703 MPa)。当预混气体当量比小于临界值时,拉伸火焰传播速度、未拉伸火焰传播速度、层流燃烧速度和燃烧压力随当量比增加而增加;而当预混气体当量比大于临界值时,速度和压力随当量比增加而减小。
The present paper is aimed at introducing our e xperimental study of the burning characteristics of methane-air mixture in the constant-volume bombs. For our research purpose, we have set up a measuring sys tem of the gas fuel combustion by means of Schlieren system, pressure sensor and high-speed camera. On the basis of the experiment we have engaged in, we have made a systematic analysis of the effects of the equivalence ratio on the burnin g characteristics of the methane-air mixture. Based on our observation, it has been found that there exists a variation of equivalence ratios ranging from 0.6 to 1.4 between the stretched flame propagation speed and combustion pressure o f methane at the initial temperature of 300 K and the initial pressures of 0.10 MPa. To make a comparison and contrast, we have also analyzed the unstretched f lame propagation speed and laminar burning velocity, and discovered that the res ults we have found are available in the literature related with the experimental data. Statistically speaking, the equivalence ratio has a strong effect on the stretched flame propagation speed, and so does the unstretched flame propagation speed and the laminar burning velocity. In other words, the greater the equival ence ratio, the greater the velocities would become. Nevertheless, there would o ccur a turning shift in the equivalence ratio of 1.1, that is, the velocity ten ds to get smaller due to the increase of equivalence ratio. Thus, the pressure d ata we have extracted from our experiment reveal a strong correlation between th e combustion pressure and the equivalence ratio, that is to say, the pressure te nds to increase first, and then tends to decrease with the increase of the equiv alence ratios, with the maximum of the equivalence ratio （0.703 MPa） to be comi ng up being the one to one （1.1）. This tendency suggests that there exists a co mmon experimental law among the four aspects of the stretched flame propagation speed, the unstretched flame propagation speed, the laminar burning velocity and the combustion pressure. Furthermore, there might be existing a critical equiva lence ratio of 1.1, indicating that the velocity and the pressure tend to incre ase with the increase of the equivalence ratio before reaching the critical equi valence value. However, once the critical equivalence ratio comes beyond the ind icated value, there would come about the decreasing trend, which should be taken as the best condition to reach the critical equivalence ratio, for the stretche d flame propagation speed （2.548 m/s）, the unstretched flame propagation speed （2.767 m/s）, the laminar burning velocity （0.368 m/s） and the combustion p ress ure （0.703 MPa） may all be reaching their highest values. Thus, it can be concl uded that this paper has provided highly essential and helpful information for the unexpected fire or explosion accidents to be taking place in advance so as for the engineers and the other personnel involved in-situ to give warning and take timely measures to get rid of any likely disasters.
出处
《安全与环境学报》
CAS
CSCD
北大核心
2014年第2期5-9,共5页
Journal of Safety and Environment
关键词
安全工程
燃烧速度
定容燃烧弹
甲烷
燃烧压力
safety engineering
burning velocity
constant-volumecombustion bomb
methane
combustion pressure
