Angular pattern of the scattered light and the Lorenz-Mie theory for the study of oil sprays

The angular pattern of the polarization ratio ? (?)-CHH (?)/CVV (?)of the light scattered by droplets has been computed according to the Lorenz-Mie theory in the size range from 0.02 to 50 ?m. It was found that the scattering due to the smaller droplets with a typical size of about 1 ?m is dominated by surface wave effects and the angular pattern presents a relevant polarization peak in the backscattering region. This scattering feature has been successfully applied to the characterization of aerosols of light and heavy oils with a Junge size distribution function. The angular pattern of light scattered by sprays of heavy oil atomized by air-assisted nozzle presents a similar maximum of the polarization ratio in the backscattering region, thus showing that a large concentration of micron-sized droplets are also present under these conditions. A quantitative comparison of the data with the Lorenz-Mie Theory indicates that the overall size distribution of the sprays is bimodal and that the atomization efficiency has a great effect on the ratio of the number concentration between the smaller particles and those larger than 20 ?m.