基于模拟退火的随机取向含核椭球颗粒粒径反演

Inversion of particle size of randomly-oriented coated spheroidal particle based on simulated annealing algorithm

烟颗粒的光散射数值模拟计算多采用单种匀质的球形、椭球或分形模型。实际上,多种情况下的烟颗粒并非仅由单种匀质组成,例如细水雾灭火和湿式洗涤塔除尘过程中生成的烟颗粒即是一种以碳烟颗粒作为凝结核、水为外壳的含核水凝物气溶胶颗粒。针对随机取向条件下,利用离散偶极子近似方法对轴对称的含核椭球颗粒模型进行数值模拟计算,得到光散射Mueller矩阵,并基于Lorenz-Mie散射理论,采用全局搜索能力很强的模拟退火算法,实现了单分散系的含核椭球颗粒的粒径反演。讨论分析了内核半径与外壳有效半径比q及内核折射率n对轴对称的含核椭球颗粒粒径反演的影响。粒径反演结果表明:q对含核椭球颗粒的粒径反演结果及误差影响较大,n在一定程度上影响颗粒的粒径反演。

Mostly, spherical, spheroidal or fractal structure models which are composed of single homogeneous ingredients, are used to approximate the shape of smoke particles for light-scattering numerical calculations. Actually, in many cases, a smoke particle is not simply composed of single homogeneous ingredient. For instance, water mist fire extinguishing and wet scrubbers dust removal will generate water aerosol which spherical smoke particle as the core, and water as the outer layer. This paper uses the discrete-dipole approximation method to calculate the light-scattering matrix of randomly oriented, axially symmetric coated spheroidal particle. Based on the Lorenz-Mie scattering theory, the inversion of particle size of monodisperse coated spheroidal particle is performed by simulated annealing algorithm which has a powerful ability in global searching. Then the influence of the rate of core radius and effective shell radius, and the refractive index of core to the inversion of particle size about axially symmetric coated spheroidal particle are analyzed. The results show that the rate of core radius and effective shell radius has relatively large impact on the results and errors of the particle size inversion of coated spheroidal particle. The refractive index of core produces certain effect to the results and errors of the particle size inversion of coated spheroidal particles.