Backscattering Spectrum Analysis of Nonspheroid Soot Particle
XING Jian1, 2, SUN Xiao-gang1, YUAN Gui-bin1，QI Xu2, TANG Hong1
1. Insititute of Automatic Detecting and Process Control System, Harbin Institute of Technology, Harbin 150001, China 2. College of Science, Harbin Engineering University, Harbin 150001，China
Abstract：In the process of measuring soot concentration and grain diameter, the backscattering spectrum of soot particle model was calculated to ascertain and analyze main effective factor of backscattering intenisty. In the present paper, ellipsoid, column and generalized Chebyshev, three nonspheroid models, were selected according to micrograph of practical soot particle, which aims to simulate practical soot particle with equivalent diameter of about 1 μm. T-matrix method was used to caculate backscattering spectrum of the three nonspheriod models, and the main effective factor curves of intensity were obtained, too. Both numerical computer simulations and experimental results illustrate that nonspheroid particle backscattering intensity is stronger than that of spheroid particle in the visible/infrared spectrum band, especially for generalized Chebyshev model, whose backscattering intensity can be even 3.5 times higher than that of forward scattering. Meanwhile, the absorbency non-spheroid particle (complex refractive index m=1.57-0.56i) backscattering intensity is stronger than that of non-absorbency nonspheriod particle (complex refractive index m=1.57-0.001i). Furthermore, with the increase in particle equivalent radius, the light source wavelength also needs to be increase to obtain more light intensity information. The backscattering light spectrum information provides a reasonable basis for selecting light source and measure angle.
