Clarification of Mechanism of Unsteady Combustion Phenomena by means of Luminescent Measurement of Chemical Species

由于非稳态燃烧过程是在很短的时间内进行的，同时伴随着物理和化学变化，因此很难阐明其燃烧过程的机理。然而，如果通过实验捕捉到这种机制，它就能够对现象进行建模，而且利用这种机制的仪器的发展是可望的。从这个角度来看，该项目是以一台带有透明活塞的直喷式柴油机作为应用该机构的代表性仪器来进行的。以激光诱导荧光法和弹性散射法和激光诱导白炽法同时应用于激光诱导荧光法和弹性散射法检测以[OH]自由基为代表的化学物种的二维统计空间分布。主要结论如下：(1)…近两年来：(1)利用激光诱导荧光技术获得了非定常喷雾火焰中[OH]自由基的二维空间分布。在这种情况下没有检测到自由基的例子。(2)在燃烧初期，[OH]自由基分布在燃烧室的较宽区域，即，(4)激光诱导白炽法和弹性散射法得到的碳烟的二维空间分布符合得很好。(5)在燃烧初期，碳烟连续存在于非定常喷雾火焰的包层内。(6)在燃烧室壁面附近，碳烟在整个燃烧过程中始终存在。(7)碳烟的再燃烧主要发生在扩散燃烧阶段。(8)碳烟的平均直径与时间几乎呈线性关系，为建立非定常喷雾燃烧机理模型提供了数据基础。较少

It is very difficult to clarify the mechanism of the unsteady combustion process, because it is proceeding during very short period with simultaneous physical and chemical changes. However, it is capable of modeling on the phenomena, if this mechanism is caught by experiments, and it is expected moreover the development of instruments utilizing the mechanism. From this standpoint, this project was carried out by use of a DI diesel engine with a transparent piston as the representative instrument applying the mechanism. And the objective items were the detection of 2-D statistical spatial distribution of [OH] radical as the representative of chemical species by the method of laser induced fluorescence with the system of Nd : YAG laser and Dye laser, and that of soot relating to [OH] radical owing to the simultaneous application of the elastic scattering method and the laser induced incandescence method with Nd : YAG 1 aser.The following main conlusions are derived from the experiments i … More n these two years :(1) It is possible to catch the 2D spatial distribution of [OH] radical in the flame of unsteady spray by means of the laser induced fluorescence. There was no example of the detection of the radical in this situation.(2) [OH] radical distributes in the wide region of the combustion chamber at the initial stage of combustion, that is, during the period of the pre-mixed burning.(3) [OH] radical shows the high density at the region of soot existence during the period of diffusion burning.(4) The 2D spatial distribution of soot by means of the laser induced incandescence method is corresponding well to that of the elastic scattering method.(5) Soot exists continuously at the envelope of the flame of unsteady spray at the initial stage of combustion.(6) Near the wall of combustion chamber, soot appears always through the combustion period.(7) The re-combustion of soot is active mainly during the period of diffusion burning.(8) There is almost the linear relation between the mean soot diameter and the time passing.It is useful for the construction of model of combustion mechanism of the unsteady spray to apply the experimental results mentioned above as the data base. Less