Doppler-Mie combination technique for determination of size-velocity correlation of spray droplets

Abstract

The Doppler-Mie combination technique was examined as one of the methods to obtain the distributions of diameters and velocities of droplets simultaneously as well as their mutual correlation in a burning or nonburning spray with fine discrimination in space but without disturbing the two-phase flow field. Attention was focussed on the technique of correcting the errors which inevitably occur in optical systems measuring size distribution of droplets, especially in those utilizing laser beams. A method for deriving correct probability density distributions in the velocity-diameter field from raw data involving errors in diameter values was developed. This technique was applied to burning or nonburing sprays injected from an ultrasonic atomizer. The size distributions of droplets obtained by this technique were in fair agreement with those obtained by the magnesium oxide method in diameter range between 20 and 80 μm. It was also found that velocities of droplets were distributed over a wide range regardless of their sizes.