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.

本研究的目的是观察从蒸发到燃料燃烧后的连续不稳定过程，燃料液滴簇是三维分散的燃料系统，并阐明了主要因素对流程的影响。实验主要是在本研究中进行的，在实验中利用微重力环境来减少自然对流的影响，这使注意现象变得复杂。液滴阵列和单液滴也作为实验对象。通过LIF方法进行了非侵入性测量，对火焰中的自由基物种进行了数值模拟，以更深入地理解。实验物体是大约50滴的液滴簇，大约10滴的液滴，大约10滴液滴阵列的液滴阵列。对于单液滴，我们将注意力集中在燃料和环境气体的特性影响上，并阐明了微重力实验中常规燃烧特性。我们还在正常的重力条件下进行了弱流量的液滴实验，其中自然对流的影响相对降低，并阐明了液滴火焰中烟灰和羟基自由基的分布。火焰形状的模式图和灭绝是用气速和液滴直径作为变量制成的。在模拟中复制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效果。还阐明了液滴间距，燃料特性和环境气体速度对液滴阵列的火焰扩散速度的影响，以及液滴间距对不稳定的蒸发过程的影响，对自动点的延迟时间以及微滴剂在微电气中的液滴生长的行为。