Study on Mechanism of Extinction and Re-ignition of turbulent Diffusion Flame by Skeletal Chemistry

湍流扩散火焰是应用广泛的最基本的火焰之一。然而，燃烧是一种极其复杂的现象，它结合了许多物理、化学过程，目前还没有得到足够的阐明。这些技术虽然在研究技术上有了计算机数值计算和激光测量技术的实验，取得了长足的发展，但也存在一些问题。在数值计算中，针对湍流模型和化学反应机理的问题，采用了高精度迎风差分格式和基于大细节基元反应机理的骨架化学方法。另一方面，针对实验中图像处理的快速性和分辨率问题，采用了目前已经积累起来的仪器技术，并在此基础上进行了以下研究。首先，用骨架化学方法对层流逆流扩散火焰进行了计算，验证了该反应模型的正确性。此外，还进行了非定常计算，阐明了详细的消光过程。其次，利用骨架化学方法对三重火焰进行了计算，考察了燃料当量比对火焰结构的影响，验证了二维流计算方法的有效性。此外，还对不同雷诺数下的二维湍流喷流扩散火焰进行了计算，考察了火焰的熄灭和再燃情况。此外，还考察了每个基本过程的作用。利用现有的激光测量系统和高速摄像机对高速和高分辨率评价进行了测量，作为与上述数值计算相对应的实验。

The turbulent diffusion flame is one of the most fundamental flames used in a wide variety of applications. However, combustion is an extremely complex phenomenon combining a lot of physical, chemical processes and enough elucidation is not yet done. Some problems exist in these techniques though there are a numerical calculation by the computer and an experiment by the laser measurement technology in the research technique to accomplish outstanding development recently. The Upwind difference scheme of higher-order accuracy and the skeletal chemistry based on the large detailed elementary reaction mechanism were adopted to cope with the problems of the turbulent flow model and the chemical reaction mechanism in a numerical calculation. On the other hand, the instrumentation technology which had accumulated up to now was adopted to cope with the problems of taking a picture to the fast process and the resolution on the image processing in the experiment.Following researches were done based on such techniques.1. First of all, the laminar counterflow diffusion flame was calculated by using the skeletal chemistry and this reaction model was clarified that enough validity was possessed. Moreover, the unsteady calculation was done and a detailed extinction process was clarified.2. Next, the triple flame was calculated to examine the influence of the fuel equivalence ratio on the flame structure by using the skeletal chemistry, and the validity of the calculation technique for the two-dimensional flow was verified.3. In addition, two-dimensional turbulent jet diffusion flame was calculated for the various Reynolds numbers to examine the extinction and the re-ignition of flame. Moreover, the role of each elementary process was examined.4. The high speed and the high-resolution evaluation were measured as an experiment corresponding to a numerical calculation of the above-mentioned with an existing laser measurement system and a high-speed video camera.