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Optimizing Selection of Controllable Variables to Minimize Downwind Drift from Aerially Applied Sprays

Published by the American Society of Agricultural and Biological Engineers, St. Joseph, Michigan www.asabe.org

Citation:  Applied Engineering in Agriculture. 28(3): 307-314. (doi: 10.13031/2013.41487) @2012
Authors:   Y. Huang, W. Zhan, B. K. Fritz, S. J. Thomson
Keywords:   Spray drift, Aerial application, Simulation, Optimization, Monte Carlo analysis

Drift of aerially applied crop protection and production materials was studied using a novel simulation-based approach. This new approach first studied many factors that can potentially contribute to downwind deposition from aerial spray application to narrow down the major contributing factors. An optimization process was then applied to reduce the negative impact from one of the main factors, wind speed. With the focus on major contributing factors such as wind speed, release height, and droplet size, the optimization process was performed in AGDISP and MATLAB. This resulted in a near-optimal offset of the flight trajectory in the direction perpendicular to the swath lines to compensate for wind speed. The effect of the near-optimal offset, i.e., the swath offset, was then validated using the Monte Carlo analysis: random values for all the factors were generated; the near-optimal swath offset values were used in comparison to the default one-half swath width offset; the difference between results using the default and the near-optimal offset was analyzed. Statistical analysis of results showed that using the near-optimal offset values can greatly reduce downwind drift as compared to the default offset value. The near-optimal offset values achieved results very close to the optimal ones. For the comparison of application efficiencies, the cumulative downwind deposition between 30.48 and 45.72 m (100 and 150 ft), and the deposition at 30.48, 76.2, and 152.4 m (100, 250, and 500 ft) were used as the performance metrics. The new method can provide some guidance to applicators. For instance, in order to achieve a certain application efficiency value, certain constraints on wind speed, release height, and droplet size must be satisfied.

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