FLAME STABILITY AND STRUCTURE OF TURBULENT PREMIXED FLAME IN A STAGNATION POINT FLOW

驻点流中湍流预混火焰的火焰稳定性和结构

• 批准号: 03650056
• 负责人: UEDA Toshihisa
• 金额: $ 1.34万
• 依托单位: KEIO UNIVERSITY
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for General Scientific Research (C)
• 财政年份: 1991
• 资助国家: 日本
• 起止时间: 1991 至 1992
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-03650056/
• 关键词: Turbulent Premixed Flame; Stagnation Point Flow; Extinction; Turbulent Burning Velocity; Flame stretch; Flame Curvature; Lewis Number Effect; Fractal; 乱流予混合火災

Flame stability and structure of a wrinkled laminar flame in a stagnation point flow have been studied experimentally. The characteristics of an approaching flow were estimated by measuring the centerline velocity profile with LDV. The flame front image was taken by using the laser tomographic method and the flame curvature was estimated by analyzing the tomographic image with image processor. The conclusions are as follows.1. For the lean propane/air flame, whose Lewis number is larger than unity, the total stretch rate defined as a sum of flame stretch due to flow divergence and that due to flame curvature is a primary parameter for the flame extinction. On the other hand, lean methane/air flame, whose Lewis number less than unity, is extinguished under the influence of the heat loss to the wall. These indicate that the Lewis number effect plays an important role for the flame extinction and the extinction mechanism can be treated as similar to that of the laminar flame when the flame stretch is reasonably estimated by taking into account the effect of flame curvature.2. From the tomography image of high speed 16mm films, the flame front movement is shown and the variation of the flame curvature is obtained. The result shows that the flame is locally extinguished when the flame reaches to the wall.3. The turbulent burning velocity depends on the product of the turbulent intensity and the flame stretch due to flame curvature.

本文对滞止点流动中起皱层流火焰的火焰稳定性和结构进行了实验研究。利用LDV测量中心线速度分布，估计了接近流的特性。采用激光层析成像方法对火焰前像进行成像，利用图像处理器对层析成像图像进行分析，估计火焰曲率。结论如下：1。对于刘易斯数大于1的稀薄丙烷/空气火焰，由气流发散引起的火焰拉伸和火焰曲率引起的火焰拉伸之和定义的总拉伸率是火焰熄灭的主要参数。另一方面，稀薄的甲烷/空气火焰，其刘易斯数小于1，在壁面热损失的影响下熄灭。这表明刘易斯数效应对火焰的熄灭起着重要的作用，当考虑火焰曲率的影响，合理估计火焰的伸长时，火焰的熄灭机理可与层流火焰的熄灭机理类似。从高速16mm薄膜的层析成像中，显示了火焰锋面的运动，得到了火焰曲率的变化。结果表明，当火焰到达壁面时，火焰被局部熄灭。湍流燃烧速度取决于湍流强度与火焰曲率引起的火焰拉伸的乘积。

项目成果

矢作 裕司,植田 利久,溝本 雅彦: "よどみ流中に形成される乱流予混合火炎に関する研究(第3報,燃焼速度に及ぼす火炎面曲率の影響)" 第29回燃焼シンポジウム前刷集. 29. 43-45 (1991)

Yuji Yahagi、Toshihisa Ueda、Masahiko Mizomoto：“滞流中形成的湍流预混火焰的研究（第 3 部分，火焰锋曲率对燃烧速度的影响）”第 29 届燃烧研讨会预印本集 29. 43-45（1991）。

Y.YAHAGI, T.UEDA AND M.MIZOMOTO: "EXTINCTION OF LEAN PROPANE/AIR TURBULENT PREMIXED FLAMES IN A STAGNATION POINT FLOW" JSME INTERNATIONAL JOURNAL II. 35. 304-309 (1992)

Y.YAHAGI、T.UEDA 和 M.MIZOMOTO：“停滞点流中贫丙烷/空气湍流预混火焰的熄灭”JSME 国际期刊 II。