Study on the Combustion and Microexplosion of an Emulsified Fuel Droplet in High Pressure Gaseous Environments

高压气体环境中乳化燃料液滴的燃烧与微爆炸研究

基本信息

批准号：
07650264
负责人：
KADOTA Toshikazu
金额：
$ 1.34万
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 (C)
财政年份：
1995
资助国家：
日本
起止时间：
1995 至 1996
项目状态：
已结题

项目摘要

An emulsified fuel droplet suspended at a tip of fine quartz fiber installed in a high pressure combustion chamber was ignited with a heated nichrome wire. A CCD camera was provided to observe a droplet flame and to determine the combustion life time and the waiting time for the onset of microexplosion. The droplet temperature was measured by using a fine thermocouple. A planar laser light scattering technique was employed for the visualization of soot field in the droplet flame. The measured results of the image of scattered light intensity were quantified by using an image analyzing system to obtain the two dimensional profile of soot concentration. Also provided was a high speed video camera for the photographic observation of the phase transition, phase separation in the liquid phase and the secondary atomization of droplet due to microexplosion. Tested were water-in-oil and oil-in water emulsified fuel with the base fuel of n-dodecane and n-hexadecane.The results showed that the combustion life time decreased with an increase in pressure, approaching a constant in supercritical gaseous environments. Increasing pressure caused an increase in the final droplet temperature which was lower than the saturated temperature of the base fuel. This became remarkable at high pressure. The phase transition and the separation of water and oil layrs was observed at high temperature of the oil-in-water emulsified fuel droplet. A spherical droplet of water suspended afloat and enclosed within the layr of base fuel. This was not the case for water-in-oil emulsified fuel droplet. The microexplosion occurred only at the pressure lower than the limit which increased slightly with increasing water content. The waiting time for the onset of microexplosion which decreased with increasing pressure was correlated with the Weibull distribution function. The maximum quantity of soot in the droplet flame increased with an increase in pressure and a decrease in water content.

用加热的镍铬合金丝点燃悬浮在高压燃烧室中安装的细石英纤维尖端的乳化燃料滴。配备CCD相机来观察液滴火焰并确定燃烧寿命和微爆炸开始的等待时间。使用精密热电偶测量液滴温度。采用平面激光散射技术来可视化液滴火焰中的烟灰场。利用图像分析系统对散射光强度图像的测量结果进行量化，得到烟尘浓度的二维分布图。还提供了高速摄像机，用于对液相中的相变、相分离以及微爆炸引起的液滴二次雾化进行摄影观察。测试了以正十二烷和正十六烷为基础燃料的油包水型和水包油型乳化燃料。结果表明，在超临界气体环境下，燃烧寿命随着压力的增加而减小，接近恒定。压力增加导致最终液滴温度升高，该温度低于基础燃料的饱和温度。这在高压下变得非常显着。在水包油乳化燃料液滴的高温下观察到相变和水层与油层的分离。悬浮在底部燃料层内的球形水滴。油包水乳化燃料滴的情况并非如此。微爆炸仅在低于极限的压力下发生，极限压力随着含水量的增加而略有增加。微爆炸发生的等待时间随着压力的增加而减少，与威布尔分布函数相关。液滴火焰中的最大烟灰量随着压力的增加和水含量的减少而增加。