A Study of Mechanism of Fuel Droplet Combustion using Laser Diagnostics in Microgravity

微重力下激光诊断燃料滴燃烧机理研究

• 批准号: 07651127
• 负责人: TSUE Mitsuhiro
• 金额: $ 1.41万
• 依托单位: University of Tokyo (1996)Osaka Prefecture University (1995)
• 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
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-07651127/
• 关键词: Combustion; Liquid Fuel; Microgravity; Laser Diagnostics; 微小重力環境; レーザ応用計測

Laser induced fluorescence method (EXCIPLEX) has been employed for remote, non-intrusive measurements of the temperature of a fuel droplet burning under microgravity. A fuel droplet doped with naphthalene and TMPD was allowed to burn in a quiescent gaseous environments. The fluorescence emission spectra from a droplet subjected to the nitrogen laser excitation were measured with an image intensified optical multichannel analyzer. The results showed that a newly developed diagnostic system was found to be applicable successfully for droplet thermometry under microgravity. The ratio of fluorescence emission intensities at two different wavelengths was an appropriate criterion for in-situ determination of droplet temperature. Two-dimensional visualization of the soot concentration profile in a flame formed around a suspended droplet was carried out under microgravity using the planar laser light scattering technique. The soot concentration and the instantaneous amount of soot were estimated approximately from the intensity of the scattered light using the image analysis system. The fuels employed were water-in-oil emulsions composed of base fuel, water and sufactant. The base fuel was n-dodecane. The water content was varied from 0 to 0.3 in volume. The sooting region can be observed spherically around the droplet by using the apparatus developed in the present work. The results showed the unsteadiness of the sooting behavior as well as the flame behavior. The maximum of the soot concentration is located in the vicinity of the inner edge of the sooting region, which corresponds to the soot shell observed previously. The time history of the instantaneous amount of soot is similar to that of the instantaneous flame radius. The maximum of the soot concentration does not vary with the water content, while the amount of soot decreases significantly with the water emulsification.

激光诱导荧光法（EXCIPLEX）已被用于远程，非侵入式测量微重力下燃料液滴燃烧的温度。用萘和TMPD掺杂的燃料液滴在静止的气体环境中燃烧。用图像增强光学多道分析仪测量了氮激光激发下液滴的荧光发射光谱。结果表明，一种新开发的诊断系统被认为是成功地适用于微重力条件下的液滴温度测量。在两个不同波长的荧光发射强度的比值是一个合适的标准，在现场测定液滴温度。利用平面激光光散射技术，在微重力条件下对悬浮液滴周围形成的火焰中碳烟浓度分布进行了二维可视化研究。使用图像分析系统从散射光的强度近似地估计烟灰浓度和烟灰的瞬时量。所采用的燃料是由基础燃料、水和表面活性剂组成的油包水乳液。基础燃料是正十二烷。水含量以体积计在0至0.3之间变化。利用所研制的装置，可以在液滴周围观察到球形的炭黑生成区域。结果表明，炭黑生成行为和火焰行为具有不稳定性。碳烟浓度的最大值位于碳烟区域的内边缘附近，这对应于先前观察到的碳烟壳。瞬时烟尘量的时间历程与瞬时火焰半径的时间历程相似。炭黑浓度的最大值不随含水量的变化而变化，但随着水乳化作用的进行，炭黑量显著降低。