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激光诱导炽光(Laser Induced Incandescence,LII)技术,由于其具有高的时间和空间分辨率,被认为是一种适合于测试碳烟浓度的技术,也可以用来测试碳烟主小球粒径。在LII测试过程中,不同激光能量密度对测试精度影响很大,高激光能量密度具有较高的信噪比,但是对于碳烟粒径测试,为了避免升华,应尽量使用低的激光能量密度。具体在利用激光诱导炽光技术推断碳烟粒径的实验中所用的低能量密度为何值,需要结合理论模型分析和实验进行确定。首先基于LII测试过程的数学模型进行了理论分析,然后在乙烯层流扩散火焰的相同位置上,测试得到了不同激光能量密度下的碳烟主小球粒径,分析确定了测试所需的最佳激光能量密度。为进一步测试碳烟的主小球粒径奠定了基础。
Laser Induced Incandescence (LII) technology, considered to be a suitable technique for testing soot concentration because of its high temporal and spatial resolution, can also be used to test soot particle size . In the LII test, different laser energy densities have a great influence on the test accuracy, and high laser energy densities have a higher signal-to-noise ratio. However, for soot particle size testing, low laser energy densities should be used to avoid sublimation. The specific value of the low energy density used in the experiment of inferring the particle size of soot by using laser-induced incandescence technology needs to be determined by theoretical model analysis and experiments. First of all, based on the mathematical model of LII test process, the theoretical analysis was carried out. Then, the particle size of soot primary particles under different laser energy densities was tested at the same position of diffusion flow of ethylene laminar flow. Good laser energy density. Which laid the foundation for further testing of the main pellet size of soot.