Simulation and test of backscattering from nonspherical soot particles swarm using laser

When the backscattering method is adopted to test the concentration and the size of soot, it´s very important to analyze the backscattering characteristics of soot to determine the optimal light source, detector and detection angle. In this paper, the backscattering characteristics of nonspherical soot particles swarm are investigated. The size and shape of soot particles are determined by microscopic measurement. According to the micrograph, both Ellipsoid model and generalized Chebyshev models are selected to imitate soot particles. With the Monte-Carlo method, a random oriented particles swarm is created, and backscattering relative intensity is calculated by T-matrix method with different parameters. A simple backscattering test system was established, in which the light source and detector are selected based on the calculation results. The numerical and experimental results show that the combination of the Monte-Carlo method and the T-matrix calculation can be successfully applied to simulate the backscattering of the nonspherical particles swarm, and the experimental system has higher backscattering intensity according to simulation result. It provides a reference for improving the measurement accuracy of particles size and concentration.