Submitted to: Transactions of the ASAE
Publication Type: Peer reviewed journal
Publication Acceptance Date: 8/21/1995
Publication Date: N/A
Citation: Interpretive Summary: About 826 million pounds (active ingredients) of pesticides are applied in the US each year and a very large portion of that is applied with sprayers. Spray drift has caused damage to crops, pollution of the environment, danger to humans and continues to be a major concern to applicators. Researchers use various targets to measure spray drift but do not know the collection efficiencies of different targets. A computer program (FLUENT) was used to determine the collection efficiencies of various sizes of droplets directed toward different targets in turbulent air streams, and an equation was developed to predict the collection efficiencies of droplet sizes common in agricultural sprays. Tests with a uniform size droplet generator in a wind tunnel verified that collection efficiencies determined experimentally agreed very well with calculated values. The results provide information needed when selecting drift targets to accurately measure spray drift.
Technical Abstract: A computational fluid dynamics program (FLUENT) was used to determine the effects of several variables on collection efficiencies of spray droplets directed horizontally toward vertical targets in turbulent air. Variables were: droplet diameter (10 to 600 um), wind velocity (0.5 to 8.0 m/s), turbulence intensity (5 to 80%) and target width (6.35 to 50.8 mm). An equation was developed to predict the collection efficiencies of water droplets for the variables. Collection efficiency increased with increasing droplet size, wind velocity and target width, but decreased with increasing turbulence intensity. Collection efficiencies calculated with FLUENT agreed very well with those determined experimentally in a wind tunnel.