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An Investigation on the Structure of Spray Flames Using the Spectral Analysis and the Image Processing of Light Emissions and Mie-scattering from Droplets

利用液滴光发射和米氏散射的光谱分析和图像处理研究喷雾火焰的结构

基本信息

批准号：
01460118
负责人：
MIZUTANI Yukio
金额：
$ 3.84万
依托单位：
Osaka University
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (B)
财政年份：
1989
资助国家：
日本
起止时间：
1989 至 1990
项目状态：
已结题

项目摘要

(1) The chemiluminescence characteristics of OH, CH, and C_2 radicals in flames were investigated and the visualization technique for radical luminescences was examined in terms of computer simulation based on the spectroscopic observation of a Wolfhard-Parker burner flame which had a geometry suitable for optical observation. Then, we developed an optical system which enabled us to separate the radical luminescences from the background flame luminosity (principally solid emission from soot) and to visualize them after processing simultaneously a few flame images obtained through different optical interference filters.(2) We constructed two identical imaging systems consisting of one or a few interference filters, an image intensifier, a set of coupling lenses and a CCD camera, and installed in each a focalーplane shutter controlled by a personal computer. Then, we manufactured a control device which enabled us to obtain the most suitable combination of flame images ; e. g., an OH radic … More al luminescence image coupled with a flame image at C_2 radical emission band (principally solid emission from soot) or a Mie-scattering image of droplets, simultaneously, as well as to obtain two successive frames of a flame image.(3) We also manufactured an optical system for monitoring through appropriate filters the light emissions in OH- and CH-bands as well as the light scattered by droplets at a point in the flame.(4) The flame structure of premixed sprays was observed by visualizing the light emissions in various radical bands and the droplet Mie-scattering using the above mentioned optical devices. The image informations were combined with those of local continuous monitoring of radical emissions and Mie-scattering. The experimental results were summarized as follows : (a) Flame propagated preferentially through the regions where gaseous fuel and droplets coexisted ; (b) In case of a small liquid-fuel fraction in the total fuel (consisting of liquid kerosene, and the vapors of kerosene and/or propane), the liquid fuel (droplets) completed evaporation and combustion in a thin reaction zone, and the gas-phase reaction in premixed-combustion mode prevailed throughout a whole droplet cluster ; (c) In case of a large liquid-fuel fraction in the total fuel, the gas-phase reaction occurred outside a large-scaled droplet cluster, whereas small dense clusters involved in it burned with diffusion flame-lets emitting intense solid emissions from soot, which implied that sprays burned not in a simple group combustion mode but in a hierarchic one. Less

(1)本文研究了火焰中OH、CH和C_2自由基的化学发光特性，并根据光学观测的Wolfhard-Parker燃烧器火焰的光谱观测，对自由基发光的计算机模拟可视化技术进行了研究。然后，我们开发了一个光学系统，使我们能够从背景火焰光度（主要是固体发射烟尘），并同时处理后，通过不同的光学干涉滤光片获得的几个火焰图像可视化的自由基发光。(2)我们构造了两个相同的成像系统，包括一个或几个干涉滤光片，一个像增强器，一组耦合透镜和一个CCD相机，并安装在每个焦平面快门由个人计算机控制。然后，我们制造了一个控制装置，使我们能够获得最合适的火焰图像组合;例如，在一个实施例中，OH基 ...更多信息将发光图像与C_2自由基发射带的火焰图像（主要是煤烟的固体发射）或液滴的Mie散射图像同时耦合，并获得连续两帧的火焰图像。(3)我们还制造了一个光学系统，通过适当的过滤器监测OH-和CH-波段的光发射以及火焰中某一点处液滴散射的光。(4)利用上述光学装置观察了预混喷雾的火焰结构，得到了不同自由基谱带的光辐射和液滴的米氏散射。图像信息与局部连续监测的自由基发射和米氏散射相结合。实验结果表明：（a）火焰优先通过气体燃料和液滴共存的区域传播;（B）在总燃料中液体燃料分数小的情况下，（由液体煤油和煤油和/或丙烷的蒸气组成），液体燃料（液滴）在较薄的反应区内完成蒸发和燃烧，气相反应以预混燃烧方式进行;（c）在液体燃料占总燃料比例较大的情况下，气相反应发生在大尺度液滴团簇之外，而小的密集液滴团簇则以扩散小火焰燃烧，从烟灰中释放出强烈的固体排放物，这意味着喷雾燃烧不是以简单的群燃烧模式，而是以分级燃烧模式。少