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The Dynamism of Combustion and Flame of Three-Dimensionally Dispersed Fuel System under Microgravity Conditions

微重力条件下三维分散燃料系统的燃烧与火焰动力学

基本信息

批准号：
16360108
负责人：
KADOTA Toshikazu
金额：
$ 8.06万
依托单位：
Osaka Prefecture University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2004
资助国家：
日本
起止时间：
2004 至 2006
项目状态：
已结题

项目摘要

The objective of the present research was to observe the successive unsteady processes from evaporation to combustion after autoignition of fuel droplet clusters, which were the three-dimensionally dispersed fuel systems, and to elucidate the effects of primary factors on the processes. Experiments were mainly conducted in the present study, and microgravity environments were utilized in the experiments for reducing the effects of natural convection, which complicated the phenomena of attention. Droplet arrays and single droplets were also included as the experimental objects. Non-intrusive measurement with LIF method and numerical simulation of radical species in the flames were conducted for deeper understanding.The experimental objects were the droplet clusters with about 50 droplets, those with about 10 droplets, the droplet arrays with about 10 droplets and the single droplets. For the single droplets, we focused our attention on the effects of properties of the fuel and the ambient gas, and elucidated the conventional combustion characteristics in the microgravity experiments. We also conducted the droplet experiments in weak flows under the normal gravity condition, where the effects of natural convection were relatively reduced, and elucidated the distributions of soot and hydroxyl radical inside the droplet flame. The mode map of the flame shape and extinction was made with the gas velocity and the droplet diameter as the variables. The results on the radical distribution were reproduced in the simulation, which included a detailed reaction model, and the obtained effects of the ambient gas humidity were confirmed. Also elucidated were the effects of the droplet spacing, the fuel properties and the ambient gas velocity on the flame spread speed of the droplet array, and the droplet spacing effects on the unsteady evaporation process, on the delay time of autoignition and on the behavior of the flame growth of the droplet clusters in microgravity.

本文的目的是观察三维离散燃料液滴团簇自燃后从蒸发到燃烧的连续非定常过程，并阐明主要因素对该过程的影响。本研究以实验为主，利用微重力环境来降低自然对流对注意现象的影响。液滴阵列和单个液滴也被包括作为实验对象。为了更深入地了解火焰中的自由基组分，本文采用激光诱导荧光（LIF）方法对火焰中的自由基组分进行了非侵入式测量和数值模拟，实验对象分别为约50个液滴的液滴簇、约10个液滴的液滴簇、约10个液滴的液滴阵列和单个液滴。对于单液滴，我们着重研究了燃料和环境气体性质对燃烧的影响，并阐明了微重力实验中常规的燃烧特性。我们还进行了正常重力条件下的弱流中的液滴实验，其中自然对流的影响相对减少，并阐明了烟灰和羟基自由基的液滴火焰内部的分布。以气速和液滴直径为变量，绘制了火焰形状和熄灭的模态图。在模拟中再现了自由基分布的结果，其中包括详细的反应模型，并确认了环境气体湿度的影响。还阐明了液滴间距、燃料性质和环境气体流速对液滴阵列火焰传播速度的影响，以及液滴间距对微重力下液滴簇非稳态蒸发过程、自燃延迟时间和火焰生长行为的影响。