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Title: Airspeed and orifice size affect spray droplet spectrum from an aerial electrostatic nozzle for fixed-wing applications

Author
item Martin, Daniel - Dan
item CARLTON, JAMES - Retired ARS Employee

Submitted to: Applied Engineering in Agriculture
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/7/2012
Publication Date: 2/15/2013
Citation: Martin, D.E., Carlton, J.B. 2013. Airspeed and orifice size affect spray droplet spectrum from an aerial electrostatic nozzle for fixed-wing applications. Applied Engineering in Agriculture. 29:5-10.

Interpretive Summary: The aerial electrostatic spraying system patented by the USDA ARS is a unique aerial application system which charges spray particles for the purpose of increasing deposition and efficacy of crop protection products. While this system has many potential benefits, very little is known about how changes in airspeed and nozzle orifice size affect droplet size of electrostatically charged sprays. Laser measurements in a high-speed wind tunnel showed that increases in airspeed produced smaller spray droplets for all tested nozzle sizes. Generally, an increase in nozzle size increased the spray droplet size at all airspeeds. Results from this study will help aerial applicators better understand how changes in airspeed and nozzle orifice size affect droplet size from aerial electrostatic nozzles, which can help improve spray deposition and reduce off-target drift.

Technical Abstract: The aerial electrostatic spraying system patented by the USDA ARS is a unique aerial application system which inductively charges spray particles for the purpose of increasing deposition and efficacy. While this system has many potential benefits, very little is known about how changes in airspeed or nozzle orifice size affect the spray droplet spectrum. The objective of this study was to quantify these effects in a controlled wind tunnel at fixed-wing airspeeds. These tests were conducted in a high-speed wind tunnel located at the USDA ARS Aerial Application Technology research facilities in College Station, Texas. Laser diffraction data showed that increases in airspeed produced smaller spray droplets for all nozzle orifices tested, as quantified by standard spray droplet parameters. Generally, an increase in nozzle orifice size increased the coarseness of the spray droplet spectra at all airspeeds. The results from this study will help aerial applicators better understand how changes in airspeed and nozzle orifice size affect droplet size from an aerial electrostatic nozzle.