汽油机中火焰辐射光谱的初步研究

A Study on Flame Emission Spectra in aSpark Ignition Engine

采用一套精密的光电系统对汽油机着火和燃烧过程中的火焰光谱进行了测量和分析，试验结果表明，着火过程中存在台不同燃烧中间产物的大量光谱，着火后ＣＨ及Ｃ２自由基的光强迅速增加，而其它自由基的光强减少了，ＣＨ自由基光强的变化较之缸内压力变化能够给出更准确的关于着火延迟及燃烧终点的信息，过量空气系数和温度的变化已经通过光学诊断技术测量过了，分别测量４３１ｎｍ和５１７ｎｍ，５０２ｕｍ和７９７ｕｍ的发光强度可以估算过量空气系数及火焰温度，过量空气系数的ＰＤＦ图（概率密度函数图）已被证明与混合气形成与燃烧有着紧密的关系。

lame emission spectra during ignition and combustion in a spark ignition engine were measured and analyzed with a precise optoelectronic system. Test results show that a large number of characteristics of different intermediate products exist during the ignition process. After themixture ignited, light intensity of CH and C2 radical increase rapidly, the light intensities of otherradicals tend to diminish. The variation of the light intensity of CH radical can give more accurateinformation about the ignition delay and the end of combustion than the variation of cylinder pressure. The fluctuations of excess air ratio and temperature in a combustion chamber weremeasured with the optical diagnostic technique. The excess air ratio and temperature were estimatedby the ratio of light emission intensities of 431nm and 517hm, 502nm and 797urn respectively. PDF (Probability Distribution Function) of excess air ratio was proved to be well correlated to mixtureformation and combustion.