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

湍流扩散火焰是最基本的火焰之一，在各种各样的应用中使用。然而，燃烧是一种结合了许多物理、化学过程的极其复杂的现象，目前还没有得到足够的阐明。近年来，激光测量技术虽有计算机数值计算和实验研究，但在研究技术上仍存在一些问题。采用高阶精度的迎风差分格式和基于大细节基本反应机理的骨架化学，解决了湍流模型和化学反应机理在数值计算中的问题。另一方面，在实验中采用了迄今为止积累的仪器技术，解决了在图像处理上拍照速度快、分辨率不高的问题。基于这些技术进行了以下研究。首先利用骨架化学对层流逆流扩散火焰进行了计算，证明了该反应模型具有足够的有效性。此外，还进行了非定常计算，详细阐述了消光过程。其次，利用骨架化学方法对三元火焰进行了计算，考察了燃料当量比对火焰结构的影响，并对二维流动计算技术的有效性进行了验证。此外，还计算了二维湍流射流扩散火焰在不同雷诺数下的熄灭和重燃情况。此外，还考察了各基本过程的作用。利用现有的激光测量系统和高速摄像机进行了上述数值计算，并作为实验测量了高速和高分辨率评价。

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.