分形碳烟粒子的散射特性研究

Research on the light scattering property of fractal soot particles

基于分形的基本概念,模拟了自然界中由燃烧过程所产生的碳烟粒子的分形结构.并结合研究多体散射问题的T矩阵方法以及矢量球谐函数的加法定理,计算了结构不同、组成体系粒子数目不同碳烟粒子体系的线性极化度以及电磁散射强度特性.计算结果显示体系散射矩阵的角分布与其结构特征紧密相关.对粒子数目相同,结构不同的分形粒子其前向散射强度几近相同;但对组成结构相同粒子总数不同的粒子体系,其前向散射强度却可以加以分辨.

Based on the fundamental conception of fractal, we simulate fractal-like clusters of spheres. Calculations are performed on these spheres, whose refractive index values are characteristic of carbonaceous soot. The T matrix approach together with the translation addition theorem for vector spherical waves is employed to solve the aggregate scattering problem. Numerical results for scattering intensity and the linear polarization ratio of soot particles with different fractal structures or different particle numbers are illustrated. The sensitivity of the scattering diagram to optical characteristics of fractal-like soot agglomerates is also discussed. The result shows that the scattering intensity in the forward direction can be used carefully to distinguish soot clusters with different particle numbers. As the number of spheres in soot particles has a closed relationship with the process of burning, this study may be of great importance in predicting of the exhaust gases, heat transfer rate, etc.