Two-dimensional imaging of fuel-vapour concentration by use of LIEF technique during mixture formation process in a DI diesel engine
Two-dimensional imaging of fuel-vapour concentration by use of LIEF technique during mixture formation process in a DI diesel engine
复制标题
DOI：
10.1088/0957-0233/13/3/322
复制
发表时间：
2002-02
影响因子：
2.4
通讯作者：
H. Fujimoto;Dae Choi;Yuta Shima;J. Senda
中科院分区：
文献类型：
--
作者：
H. Fujimoto;Dae Choi;Yuta Shima;J. Senda
基于光谱分辨双色荧光发射的激光诱导激基复合体荧光(LIFE)技术已应用于蒸发柴油喷雾中，以同时分离二维图像上的液相和汽相。激基缔合物体系是基于Melton提出的TMPD/萘体系。利用该技术对混合气形成过程中液、汽相的时空分布进行了检测。在Lef技术中，汽相由单体荧光检测，而液相由激基络合物荧光跟踪。它能够为应用统计熵概念提供有关扩散状态的定量信息。为了研究蒸发式柴油喷雾中汽相的扩散过程，将这一概念应用于Lef测量得到的图像集上。用激光阴影图来推断湍流混合对点火的影响。实验在直喷式柴油机上进行，需要光学通道才能进行二维激光成像。结果发现，点火发生在湍流混合推进了燃料蒸汽和空气的近乎均匀的混合物的区域。Lef获得的多截面图像表明，燃烧室内汽相燃料的着火存在空间相关性。
The laser-induced exciplex fluorescence (LIEF) technique, which is based on spectrally resolved two-colour fluorescent emissions, has been applied to an evaporating diesel spray for the simultaneous separation of liquid and vapour phases on the two-dimensional images. The exciplex system is based on the TMPD/naphthalene system proposed by Melton. The temporal and spatial distribution of liquid and vapour phases during the mixture formation process was detected by this technique. In the LIEF technique, the vapour phase is detected by the monomer fluorescence while the liquid phase is tracked by the exciplex fluorescence. It is able to provide quantitative information on the diffusion state for applying the statistical entropy concept. This concept was put into practice in the image sets obtained through LIEF measurement in order to investigate the diffusion process of vapour phase in the evaporating diesel spray. The laser shadowgraph was taken to deduce the effect of turbulent mixing on the ignition. The experiments were conducted in a direct injection diesel engine with optical access required for the two-dimensional laser imaging. From the results, it is found that ignition occurs in the region where turbulent mixing has advanced a nearly homogeneous mixture of fuel vapour and air. Multi-sectional images obtained by LIEF indicate that there is a spatial dependence of ignition on the vapour-phase fuel in the combustion chamber.