采用同步辐射小角X射线散射(small-angle x-ray scattering,SAXS)技术,研究了柴油机燃用不同甲醇掺混比例(0、5%、15%)的甲醇/柴油混合燃料(分别记为M0、M5和M15)时颗粒的微结构。通过对散射强度和散射矢量进行不同变换和处理,结合分形理论和小角散射理论,得到了颗粒的空间结构、表面形态及团粒间隙和尺寸等参数。研究结果表明:与柴油燃烧颗粒相比,随着燃料中甲醇掺混比例增大,燃烧颗粒中的电子密度差逐渐增大,颗粒的尺寸减小;颗粒表面较为粗糙无序;M0、M5、M15的团粒间隙分别主要分布在5-7nm、8-10nm、11-13nm,团粒间隙的尺寸和数量呈上升趋势;团粒间隙分维数与团粒尺寸呈正相关,掺混甲醇后随着颗粒团粒尺寸的增大,颗粒的分布越松散,团粒结构越不稳定。
The microstructures of methanol/diesel (M0, M5, M15) combustion particles were investigated by means of synchrotron small-angle X-ray scattering (SAXS). By means of different conversion and processing on scattering intensity and scattering vector, together with SAXA and fractal theory, the particle microstructure information was obtained including spatial structure, surface morphology, aggregate gap and aggregate size. The results show that increased methanol blend ratio would make the electron density difference of combustion particles increase, the particles size reduce, the particle surface become rough and disorderly and the aggregate gap and aggregate size increase. The aggregate gap of M0, M5,M15 mainly distributed at 5-7 nm, 8-10 nm, 11-13 nm. The fractals of aggregate gap had a positive correlation with aggregate size, which indicated that the distribution of the particles would be looser and the granular structure would be more unstable, along with the increase in methanol blend ratio and aggregate size.