| Fire detection is one of the key means of fire prevention and control.Smoke is the main detection component of fire detection.However,the existing smoke detectors only detect based on simple light intensity changes,and there is a problem that they cannot distinguish fire particles from other interfering particles.The scattering matrix contains rich information such as particle shape,size,and refractive index.Analyzing the difference between fire particles and interference particles from the light scattering matrix information can reduce the false alarm rate of detection.The detector provides theoretical support.At present,there are many studies on the light scattering matrix of a single fire and atmospheric aerosol particles.However,in the real atmosphere and fire environment,the particles are diverse,and the particles will be mixed in various states.,so it is not only necessary to study a single particle,but also to further study the mixed state of fire particles and interfering particles and the light scattering matrix in the mixed state.In this paper,an aerosol generator is used to generate water mist,the particle size distribution of water mist is measured by a particle spectrometer,and the light scattering matrix of water mist is calculated by using Lorenz-Mie theoretical programming.Basically the same,verifying the reliability of the experimental platform.By designing a combustion chamber and carrying out combustion experiments,the black carbon particles produced by combustion are collected,and then the black carbon particles are dispersed by a dust aerosol generator,and the redispersed black carbon particles are measured by light scattering.Modeling of carbon particles,the effect of particle size variation on light scattering properties is simulated using the Tmatrix method.The Arizona standard dust was selected as the interference particle,and the light scattering matrix of the standard dust was measured through the platform.From the light scattering matrix elements F22/F11,-F12/F11,and F44/F11,black carbon particles and dust particles can be effectively distinguished.According to the electron microscope Hexagonal prisms and ellipsoids were selected for dust modeling research on the photographed dust morphology.Through dipole approximation calculations,it was found that hexagonal prisms and ellipsoids could not reproduce the properties of real dust particles very well.Considering the environment where multiple particles coexist in reality,black carbon particles and dust particles are mixed in different proportions,the mixing state of the mixed particles is analyzed by shooting an electron microscope,and the light scattering matrix is measured for the mixed particles with different mixing ratios to obtain the distribution law of light scattering matrix of mixed particles.In this paper,the light scattering model of different amounts of black carbon adhering dust is generated,and the light scattering properties of the model are calculated by the T-matrix,and the influence of different amounts of black carbon attached to dust is explored,and the light scattering properties of mixed particles are mainly the light scattering properties of black carbon and dust.The research shows that particles can be distinguished from different angles of different scattering matrix elements.The research results can provide a basis for characterizing real environment particle mixing and building a mixed particle model.Through the difference of different particle light scattering matrices,smoke detectors Distinguishing between fire smoke particles and interfering particles provides theoretical basis guidance,which is of great significance for the development of antifalse alarm and high-precision fire detectors... |
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