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A Study on Spray Combustion in Supercritical Environments

超临界环境喷雾燃烧研究

基本信息

批准号：
63460100
负责人：
HIROYASU Hiroyuki
金额：
$ 4.48万
依托单位：
HIROSHIMA 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：
1988
资助国家：
日本
起止时间：
1988 至 1989
项目状态：
已结题

项目摘要

A basic research was conducted on mechanisms of spray combustion in pressurized and heated ambient gas beyond the critical point of liquid fuel, that is, supercritical environments. The current research includes the following three items : (1) Blue Flame Combustion in a Jet-Mixing-Type Spray Combustor (2) Fuel Vapor Concentration and Mean Drop Diameter in a Spray Injected into Supercritical Environments (3) Drop Evaporation and Combustion in Supercritical Environments on a Hot Wall.The principal results of the experiments listed above are as follows: (1) Mechanisms of blue flame combustion were investigated by the measurement of temperature distribution in a flame and the sampling analysis of combustion contents in a flame. Oxygen concentration and temperature around a nozzle in blue flame combustion were higher than in yellow flame combustion. Acetylene concentration in a flame showed higher value in a yellow flame. (2) Fuel vapor concentration in a spray injected into supercritical environments was measured by the image processing technique of a reconstructed hologram. The radial distribution of the fuel vapor concentration showed a low value at the center and the edge of the spray, and took a maximum between them. Mean drop diameter of the spray was measured by the optical analysis of the Fraunhofer diffraction light. The mean drop diameter increased once, then decreased with an increase of the ambient temperature. (3) Evaporation and combustion processes of a fuel drop in supercritical environments on a wall were observed in a pressure vessel. The evaporation lifetime in air was found to be shorter than that in nitrogen at the same wall temperature. As the ambient pressure increased beyond the critical pressure of the fuel, the end of combustion time increased in the wall temperature range just below the critical temperature of the fuel, and in the other temperature range it decreased.

对超过液体燃料临界点的加压加热环境气体（即超临界环境）中的喷雾燃烧机理进行了基础研究。目前的研究内容包括以下三项：（1）射流混合式喷雾燃烧室中的蓝焰燃烧（2）超临界环境喷雾中的燃料蒸气浓度和平均液滴直径（3）超临界环境中热壁上的液滴蒸发和燃烧。以上实验的主要结果如下：（1）蓝焰燃烧机理的研究火焰中温度分布的测量和火焰中燃烧成分的采样分析。蓝色火焰燃烧时喷嘴周围的氧气浓度和温度高于黄色火焰燃烧。火焰中的乙炔浓度在黄色火焰中显示出较高的值。 (2)通过重建全息图的图像处理技术测量喷射到超临界环境中的喷雾中的燃料蒸气浓度。燃油蒸气浓度的径向分布在喷雾中心和边缘处呈现较低值，并且在它们之间呈现最大值。通过夫琅和费衍射光的光学分析来测量喷雾的平均液滴直径。随着环境温度的升高，平均液滴直径先增大后减小。 (3)在压力容器内观察超临界环境下燃料滴在壁上的蒸发和燃烧过程。发现在相同壁温下，空气中的蒸发寿命比氮气中的蒸发寿命短。当环境压力增加到超过燃料的临界压力时，燃烧结束时间在略低于燃料临界温度的壁温范围内增加，而在其他温度范围内则减少。