Spray spectrum modifications through changes in airspeed to minimize drift
By
Bradley K. Fritz, Bill E. Bagley, W. Clint Hoffmann, Yubin Lan
Contact: Dr. Brad Fritz E-mail: brad.fritz@ars.usda.gov
Summary:
Management of droplet size is one of the key components to minimizing spray drift, which can be accomplished in-flight by changing airspeed. Studies were conducted measuring spray droplet spectra parameters across airspeeds ranging from 100-140 mph (in 5 mph increments). In general the volume median diameters decreased 30-50% as airspeed increased with similar increases in the percent of the spray volume less than 100 μm. To determine the extent to which these changes in droplet spectra data impacted downwind drift, AGDISP was employed to estimate how varying airspeed along sequential flights swaths near a downwind field edge impacted total off field spray drift. Spray drift was modeled across multiple sequential spray swaths at both constant airspeeds across all swaths and at scenarios where near field edge swaths were flown at lower airspeeds (thus larger droplet sizes) to determine the level to which spray drift is reduced.
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