预混火焰中一氧化氮平面激光诱导荧光测量方法研究

发布时间：2018-02-04 12:57

  本文关键词： 平面激光诱导荧光 NO分布特性 平焰燃烧器 ICCD关键参数　出处：《哈尔滨工业大学》2015年硕士论文　论文类型：学位论文

【摘要】：随着社会文明和科学技术的快速发展,人类开始进行大规模的物质生产活动,生产活动所产生的大量工业垃圾和生活垃圾,造成了严重的生态环境污染,其中非常值得关注的就是大气污染。目前我国大气污染问题尤为严重,尤其是北方各大城市出现的雾霾、PM2.5值偏高等现象已经为人们敲响了警钟。大气污染主要来源于工业废气、生活燃煤、汽车尾气等。其中以一氧化氮为主的氮氧化合物是主要的气体状态污染物之一。为了了解汽车尾气和煤炭燃烧产生的NO气体时空分布特性,进一步改善控制氮氧化合物排放的燃烧设备,本文将应用平面激光诱导荧光(Planar Laser-Induced fluorescence,简称PLIF)方法研究甲烷/空气预混火焰尾焰中一氧化氮分子的时间和空间分布特性。PLIF测量方法主要是将激光整形成片状光束,将粒子激发到高能态,通过测量从高能态跃迁到低能态的荧光来获取某个截面的信息,通过改变激发位置,即可获取流场任意空间位置的荧光信息。NO-PLIF(Planar Laser-Induced fluorescence of Nitric Oxide,简称NO-PLIF)测量方法就是利用PLIF技术获取流场中NO分子任意时间、空间位置的荧光信息。本文首先研究了NO分子跃迁能级系统的理论公式,确定了NO-PLIF信号强度与入射激光能量、NO分子数密度等变量和荧光辐射效率、探测系统常量的关系;同时应用LIFBASE仿真软件对NO分子X2∏→A2∑(0,0)跃迁能级的吸收系数进行仿真,确定选择NO分子激发波长的范围,校正激光器波长的偏移量在1.9~4.2pm范围内,选出了NO分子跃迁分支为Q1(12)+Q12(20)+Q2(20)(226.033nm),选出了激光器波长为226.029nm;根据棱镜分光原理对入射激光能量进行定标,实现了激光能量的实时检测;实验时首先令入射激光能量在0.1~1.1m J范围内变化,验证了NO-PLIF信号强度随着入射激光能量的增加而增加,证明此时激光能量较弱,PLIF信号强度未饱和,满足实验条件;其次通过控制变量法选出ICCD相机最佳延时为133ns,最佳门宽为20ns,最佳累计次数为20次;最后,在满足NO-PLIF技术的最佳实验条件下,改变预混气体当量比0.7~1.3,实验结果表明NO-PLIF信号强度随着当量比的增加而增加,平行于燃烧器表面方向的NO分布较均匀,同时应用罗丹明染料对激发激光能量的纵向分布进行修正,修正后不同当量比下NO-PLIF信号强度随着高度的增加有微弱的下降趋势,说明此时NO浓度随着高度的增加而减少。
[Abstract]:With the rapid development of social civilization and science and technology, human began to carry out large-scale material production activities, the production of a large number of industrial waste and domestic waste, resulting in serious ecological pollution. The problem of air pollution in China is especially serious at present, especially the haze that appears in the big cities in the north. The phenomenon of high PM2.5 value has sounded the alarm for people. Air pollution mainly comes from industrial waste gas and coal burning in daily life. In order to understand the spatial and temporal distribution characteristics of no gas produced by automobile exhaust and coal combustion, the nitrogen and oxygen compounds, which are mainly nitric oxide, are one of the main gaseous pollutants. To further improve the combustion equipment for nitrogen oxide emission control, planar laser-induced fluorescence planar Laser-Induced fluorescence will be used in this paper. The temporal and spatial distribution of nitric oxide in methane / air premixed flame tail flame is studied by PLIF.The main method of PLIF measurement is to shape the laser beam into a flake beam. The particle is excited to the high-energy state, the fluorescence from the high-energy state to the low-energy state is measured to obtain the information of a cross section, and the excitation position is changed. The fluorescence information of any spatial position of the flow field. NO-PLIFF can be obtained. Planar Laser-Induced fluorescence of Nitric Oxide. The measurement method of NO-PLIFI is to use PLIF technology to obtain the arbitrary time of no molecule in the flow field. In this paper, the theoretical formula of the transition level system of no molecule is studied, and the intensity of NO-PLIF signal and the incident laser energy are determined. No molecular number density and other variables and fluorescence radiation efficiency, detection system constant relationship; At the same time, the LIFBASE simulation software is used to simulate the no molecule X2 蟺. 鈫扵he absorption coefficient of A _ 2 鈭，

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