Study On The Laser Light-Scattering Field Properties Of Soot Aerosol

The detection of soot discharge is an important means to control the contamination and forecast the growing trend of the soot pollution. With more strict standards of soot discharge, traditional soot density measurement techniques cannot adequately meet these requirements. Due to the properties of transient measurement, wide measurement range and non contact measurement, the measurement of soot density will become an important testing method, and will be widely used in the field of measurement.This paper focused on the propagation model of laser in the soot aerosol and the experimental verification method of soot density detection. The main work is as follows:Firstly, according to the theory of electromagnetic wave scattering of single particle and Mie scattering theory, the light-scattering model of single particle was established. The optical properties of soot particles were simulated and calculated by MATLAB software, including such as scattering coefficient, extinction coefficient, asymmetry factor and single albedo and so on.Secondly, based on the theory of radiation transport and multiple scattering of Twersky, the paper established the propagation model of of soot aerosol, and studied the multiple scattering of soot particles through the Monte Carlo method, the numerical simulation of the transport process is carried out in the MATLAB development environment. The results of the numerical simulation was used to analyze the variation of scattering intensity with the scattering angle and soot thickness of different particle characteristic parameters(particle size, incident wavelength, particle number density).Then, The detection scheme of the scattering field properties of soot aerosol was designed. The paper described the working principle of the detection system and selected the light source, optical components, photoelectric detectors and other key devices of the detection system, at the same time, designed the circular opto-electronic detector and accomplished the design and implementation of the hardwave circuit of the photoelectric array detection circuit.Finally, the scattered light intensity distribution of different scattering angles was measured and analyzed to select the best wavelength by building a prototype testing platform, and completed the calibration of concentration detection system, analyzed the errors of the experiment.Through the theoretical analysis and experimental study, it was indicated that the theoretical model is feasible, which layed a foundation for the detection of soot particle density in a more complex multi dispersion.