Walewski J W, Nyholm K, Dreizler A, Aldén M
Division of Combustion Physics, Lund Institute of Technology, P.O. Box 118, SE-22100 Lund, Sweden.
Appl Spectrosc. 2004 Feb;58(2):238-42. doi: 10.1366/000370204322842995.
The potential of polarization spectroscopy for the detection of trace constituents in sooting combustion was investigated. It was demonstrated that the directionality of the polarization spectroscopy signal can be exploited to efficiently suppress incoherent interferences, e.g., Rayleigh scattering at soot particles. We also show how polarization spectroscopy compares with laser-induced fluorescence in this type of environment by applying both techniques to atmospheric-pressure, premixed propane/oxygen flames. The acquired signals were spatially resolved along the centerline of the flame, and measurements were conducted at several heights above the burner head and for medium to very high fuel-to-oxidizer ratios. Through our work we found that polarization spectroscopy can be applied even in the presence of large soot fractions. For most conditions, where laser-induced fluorescence suffered from interferences like elastic scattering, spatially filtered polarization spectroscopy signals were virtually background-free, and only for high soot loads did a noticeable background on the latter signal appear. This background likely stems from Mie scattering at very large soot particles.
研究了偏振光谱法在检测烟灰燃烧中痕量成分方面的潜力。结果表明，偏振光谱信号的方向性可用于有效抑制非相干干扰，例如烟灰颗粒上的瑞利散射。我们还通过将偏振光谱法和激光诱导荧光技术应用于大气压预混丙烷/氧气火焰，展示了在这种环境下偏振光谱法与激光诱导荧光法的比较情况。采集的信号沿火焰中心线进行空间分辨，并在燃烧器头部上方的几个高度以及中等至高燃料与氧化剂比的条件下进行测量。通过我们的工作发现，即使在烟灰含量很高的情况下，偏振光谱法也能应用。在大多数情况下，激光诱导荧光会受到弹性散射等干扰，而空间滤波后的偏振光谱信号几乎没有背景，只有在烟灰负载很高时，后者的信号才会出现明显的背景。这种背景可能源于非常大的烟灰颗粒的米氏散射。
