Airspeed and Orifice Size Affect Spray Droplet Spectrum from an Aerial Electrostatic Nozzle for Fixed-wing Applications

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 of charged spray. This study quantified these effects in a controlled high-speed wind tunnel at fixed-wing airspeeds (177-306 km/h). These tests were conducted 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.