多波长消光法粒径测量中颗粒形状的影响

Effect of Particle Shape on Particle Size Measurement in Multi-Wavelength Light Extinction Method

对多波长消光法颗粒测量方法中非球形颗粒形状的影响进行研究。采用广义米散射理论数值模拟计算了不同长短轴椭球颗粒在不同入射角度下的消光截面和消光系数,并与等效球形颗粒的消光特性进行比较,结合Lambert-Beer定律计算消光谱,采用正则化算法反演椭球颗粒粒径,进而分析椭球颗粒形状对粒径测量结果的影响。结果表明,与球形假设相比,椭球颗粒的形状改变使得粒径反演结果产生较大偏差。本算例中,对于亚微米颗粒,当形状参数a/b=5时,其相对偏差可能超过90%。

The effect of non-spherical particles shape on particle measuring method based on multi-wavelength light extinction method is investigated. According to the generalized Mie scattering theory, the extinction section and extinction coefficient of spheroidal particles with different maior and minor axes under different incident angles are calculated by numerical simulation, and they are compared with the extinction characteristics of equivalent spherical particle. The extinction spectrum is calculated by combining with Lambert-Beer law, and the particle size of the spheroidal particles is inversed by regularization algorithm. Then the influence of the shapes of the spheroidal particles on particle size measurement result is analyzed. The results show that the change of spheroidal particle shape will bring significant deviation to the inversed particle size result compared with spherical assumption. In this paper, relative deviation can exceed 90% for submicron particles under shape parameter a/b of 5.