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Optical and Numerical Analyses of Vortex-Flame Interaction Using Simultaneous and Two-Directional High-Speed Schlieren Photography and Discrete Vortex Method

使用同步和双向高速纹影摄影和离散涡旋方法对涡旋火焰相互作用进行光学和数值分析

基本信息

批准号：
16560182
负责人：
OHIWA Norio
金额：
$ 2.37万
依托单位：
Nagoya Institute of Technology
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2004
资助国家：
日本
起止时间：
2004 至 2005
项目状态：
已结题

项目摘要

The behavior of the propagating flame after the spark ignition in the plane propane-air premixed shear layer is first observed in this paper by combining the following two devised techniques; the acoustic excitation of the plane shear layer and the simultaneous and two-directional schlieren system. To obtain characteristic flame appearances due to the vortex-flame interaction in the plane premixed shear layer, another special idea of assigning two extreme points of ignition is introduced; one at the center of an organized eddy where the vortex motion plays an important role, and the other at the midpoint between two adjacent organized eddies where the rolling-up motion prevails. The two-dimensional change of flame outlines after the midpoint ignition is also simulated by superposing the flame movement with a constant burning velocity followed by thermal expansion on the two-dimensional vortex flow field described by the discrete vortex method. The results obtained are summarized as fol … More lows.(1) It is found that two types of the enhancement mechanisms of flame propagation exist among the organized eddies in the plane shear flow; one is the vortex bursting due to the vortex motion, the other is the vortex boosting due to the rolling-up motion, and exert quantitatively almost the same influences on the flame propagation enhancement process. Also found is that the vortex boosting which is one of the two configurations of vortex-flame interactions can be qualitatively captured by the proposed discrete vortex method.(2) The simulated lateral flame propagation velocities agree relatively well with the axial and lateral flame propagation velocities experimentally obtained from the simultaneous and two-directional high-speed schlieren images, although neglect of the combined effects of the baroclinic torque, the three dimensionality of vortex-flame interaction and the flame curvature leads to slight overestimation of the flame propagation velocity. This result verifies that the proposed two-dimensional discrete vortex method combined with Huygens' Principle is useful for qualitatively estimating and modeling the flame propagation velocity in the plane premixed shear layer, in spite of many assumptions introduced to simplify the numerical simulation.(3) The enhancement effects of flame propagation in the plane premixed shear layer are composed of the physical one due to the vortex-flame interactions and the chemical one through the laminar burning velocity. For both configurations of the vortex-flame interactions, the flame propagation velocity V_f with vortex interaction in the plane premixed shear layer is given by the vortex tangential velocity v_θ plus the propagation speed of the undisturbed flame (ρ_u/ρ_b)S_L, and expressed by the following simple linear equation.V_f=v_θ+(ρ_u/ρ_b)S_L Less

本文首次采用平面剪切层声激励和同步双向纹影技术，对丙烷-空气预混剪切层中火花点火后火焰传播过程进行了观测。为了获得特征火焰外观由于在平面预混剪切层中的涡-火焰相互作用，另一个特殊的想法分配两个极端的点火点被引入;一个在中心的有组织的涡流的涡运动起着重要的作用，和其他在两个相邻的有组织的涡流之间的中点的卷起运动占上风。通过在离散涡方法描述的二维涡流场上叠加恒定燃烧速度的火焰运动和热膨胀，模拟了中点点火后火焰轮廓的二维变化。所得结果总结如下 ...更多信息低点。(1)研究发现，平面剪切流中有组织的旋涡存在两种火焰传播强化机制，一种是旋涡运动引起的旋涡破裂，另一种是涡卷运动引起的旋涡助推，它们对火焰传播强化过程的影响在数量上几乎是相同的。同时还发现，所提出的离散涡方法可以定性地捕捉到涡-火焰相互作用的两种构型之一的涡助推。(2)模拟的横向火焰传播速度同意相对较好的轴向和横向火焰传播速度实验获得的同时和双向高速纹影图像，虽然忽略的斜压扭矩的综合影响，三维的涡火焰相互作用和火焰曲率导致轻微高估的火焰传播速度。这一结果证实了所提出的二维离散涡方法结合惠更斯原理是有用的定性估计和模拟的火焰传播速度在平面预混剪切层，尽管引入了许多假设，以简化数值模拟。(3)平面预混剪切层中火焰传播的增强效应由涡流与火焰相互作用产生的物理增强效应和层流燃烧速度产生的化学增强效应组成。对于这两种涡-火焰相互作用的构型，在平面预混剪切层中有涡相互作用的火焰传播速度V_f由涡切向速度v_θ加上未扰动火焰传播速度（ρ_u/ρ_B）S_L给出，并由以下简单的线性方程表示：V_f=v_θ+（ρ_u/ρ_B）S_L减