双火花塞对天然气定容燃烧影响的试验研究

发布时间：2018-06-13 17:06

本文选题：双火花塞 + 定容燃烧弹　；参考：《吉林大学》2016年硕士论文

【摘要】：随着我国经济的高速发展,汽车行业也随之迅速崛起,能源短缺和环境污染已经成为我国急需解决的重要问题。天然气因为储量丰富,成本低廉,安全性高等优点,成为汽车主要的代用燃料。但天然气存在燃烧火焰传播速度慢,热损失大,热效率低等问题,本文进行了双火花塞对天然气定容燃烧影响的试验研究,旨在为双火花塞点火天然气发动机的研究提供理论依据。本文在可视化的定容燃烧试验系统上进行了天然气定容燃烧试验,首先对定容燃烧试验系统进行了改进,使其适合本文实验研究;其次通过改变不同的点火方式、初始压力、初始温度以及燃空当量比进行天然气燃烧试验,并采集火焰图像和燃烧压力;然后利用MATLAB软件编写了火焰前锋面的提取程序,计算出火焰半径,进而求得火焰的传播速度和火焰前锋面面积;最后利用获取的试验数据分析不同初始参数对火焰传播速度、燃烧压力、火焰发展期、主燃烧期以及放热率的影响。研究结果表明:在不同的点火方式情况下,无论初始参数如何改变,同等初始条件下,双火花点火模式下燃烧性能要优于单火花点火模式。虽然双火花点火模式单侧火焰的传播速度较单点火模式小,火焰半径增长速度慢。但由于双火花点火模式是两侧火焰的同步传播,等同于缩短了火焰的传播距离,而且是两个火焰核心同步发展,形成火焰前锋面的面积比单点火模式大,同一时刻更多的混合物参与了化学反应,能够得到较大燃烧压力峰值和燃烧放热率峰值,明显的缩短了火焰发展期和主燃烧期,有效的提高了天然气的燃烧效率。在不同的初始压力情况下,随着初始压力的升高,混合气的浓度增大,火焰半径的增长速度减慢,火焰的传播速度降低,燃烧压力的峰值和燃烧放热率不断增大,火焰发展期和主燃烧期明显延长。在不同的初始温度情况下,随着初始温度的升高,混合气活化因子的活性增加,火焰的传播速度升高,火焰半径的增长速度加快,燃烧压力的峰值和燃烧放热率不断增大,火焰发展期和主燃烧期缩短。在不同的燃空当量比情况下,化学当量比附近(当量比1.0-1.1)火焰传播速度最快,火焰半径增长速度最快,达到的燃烧压力峰值和燃烧放热率最大,火焰发展期和主燃烧期明显缩短。过浓或者过稀都会使火焰的传播速度降低,火焰半径增长速度减慢,使火焰发展期和主燃烧期延长。
[Abstract]:With the rapid development of China's economy, the automobile industry has also risen rapidly. Energy shortage and environmental pollution have become an important problem urgently needed to be solved in China. Because of its rich reserves, low cost and high safety, natural gas has become the main alternative fuel for automobiles. However, there are some problems in natural gas, such as slow flame propagation, large heat loss and low thermal efficiency. In this paper, the effects of double spark plugs on the constant volume combustion of natural gas are studied experimentally. The aim is to provide theoretical basis for the study of double spark plug ignition natural gas engine. In this paper, the constant volume combustion test of natural gas has been carried out on the visual constant volume combustion test system. Firstly, the constant volume combustion test system has been improved to fit the experimental study in this paper; secondly, by changing different ignition modes, the initial pressure has been changed. The initial temperature and air / air ratio are used to test the combustion of natural gas, and the flame images and the combustion pressure are collected. Then, the program of extracting the front surface of the flame is compiled with MATLAB software, and the radius of the flame is calculated. Finally, the effects of different initial parameters on flame propagation velocity, combustion pressure, flame development period, main combustion period and heat release rate are analyzed using the obtained experimental data. The results show that the combustion performance of double spark igniting mode is better than that of single spark ignition mode under the same initial conditions, no matter how the initial parameters are changed. Although the propagation speed of the single side flame in the double spark ignition mode is smaller than that in the single ignition mode, the growth rate of the flame radius is slow. However, because the double spark ignition mode is the simultaneous propagation of both sides of the flame, which is equivalent to shortening the flame propagation distance, and is the simultaneous development of the two flame cores, the area forming the front surface of the flame is larger than that of the single ignition mode. At the same time, more mixtures take part in chemical reaction, can get a larger peak combustion pressure and combustion heat release rate peak, significantly shorten the flame development period and the main combustion period, effectively improve the combustion efficiency of natural gas. Under different initial pressure, with the increase of initial pressure, the concentration of mixture increases, the growth rate of flame radius slows down, the velocity of flame propagation decreases, the peak value of combustion pressure and the rate of combustion heat release increase. The flame development period and the main combustion period are obviously prolonged. At different initial temperatures, with the increase of the initial temperature, the activity of the mixture activation factor increases, the flame propagation velocity increases, the flame radius increases, the peak combustion pressure and the combustion heat release rate increase. The flame development period and the main combustion period are shortened. When the ratio of combustion to air is different, the flame propagation speed is the fastest and the flame radius grows fastest in the vicinity of the chemical equivalent ratio (equivalent ratio 1.0-1.1), and the maximum combustion pressure peak and combustion heat release rate are achieved. The flame development period and the main combustion period are obviously shortened. Overconcentration or overthinning will decrease the flame propagation speed, slow down the flame radius growth rate, and prolong the flame development period and the main combustion period.
【学位授予单位】：吉林大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：U464.174

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