Efficiency of deposition of pesticide droplets on flat cards and spheres

Abstract

The mass flux of a cloud of droplets heading towards a collector can be decomposed into its horizontal and vertical components. While only the vertical mass flux contributes to droplet deposition on a flat card by the mechanism of sedimentation, both flux components contribute to deposition on a sphere by both mechanisms of inertial impaction and sedimentation. Calculated collection efficiencies decrease as wind speed increases for cards but as wind speed increases for spheres, a minimum collection efficiency is reached at a certain wind speed. The average collection efficiencies, as measured in the field trial portion of this study, are highly linearly correlated with wind speed for cards. For spheres, however, no correlation was found between the average collection efficiency and wind speed.