Droplet sizing and velocimetry in the wake of rotary-cage atomizers.

摘要

An important characteristic of liquid sprays is the statistical distribution of droplet sizes that they produce. Knowledge of the droplet size distribution is particularly important for pesticide applications because droplet size affects trajectory, probability of contact with the target pest, and the biological dose. This article describes an experimental study of the spray plume of a rotary-cage atomizer in a wind tunnel environment with an air speed typical of aerial application (60 to 70 m s-1). Comparative measurements of droplet velocity and diameter were made using phase Doppler interferometer (PDI) and laser diffraction (LD) instruments. The present study is unique because it reports full droplet velocity and size data over a range of streamwise distances from the atomizer. High droplet concentrations and strong flow recirculation in the near wake (x/D <2) were found to have a significant effect on the LD measurements. At greater downwind distances (x/D >8), droplet velocities were found to be more uniform, and droplet size measurements using LD and PDI instruments were found to be in close agreement.