Zhang Q, Deng XJ, Zhang QX, Li YD, Zhang YM (2010) Comparative study on fractal model and spherical model of fire smoke particles for light scattering. Acta Physica Sinica 59(10), 7442-7446. [In Chinese]

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Keywords:

smoke detection; fire smoke particle; fractal model; spherical model; discrete-dipole approximation; numerical-calculation; cross-section; matrix

Abstract: It is important to research light scattering from fire smoke particles by numerical calculation. Traditionally, spherical or spheroid models were used to approximate the shape of smoke particles for light scattering calculations. But actually, smoke particles have a similar fractal structure, which is different from spherical structure. Using the discrete-dipole approximation method, the light scattering Muller matrices were computed for the randomly oriented fractal aggregate, as well as the spherical particle with the same aggregate volume, and then their normalized Muller matrix elements were compared. The results indicate that the angular distributions of the normalized matrix elements F(11)(theta)/F(11)(0), F(22)(theta)/F(11)(theta) and F(34)(theta)/F(11)(theta) have significant differences between the fractal model and spherical model. We can discriminate spherical non-fire aerosols from smoke particles, using the difference of F(22)(theta)/F(11)(theta) between fractal model and spherical model.