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United States Department of Agriculture

Agricultural Research Service

Research Project: AERIAL APPLICATION RESEARCH FOR EFFICIENT CROP PRODUCTION Title: Effects of nozzle spray angle on droplet size and velocity

Authors
item Hoffmann, Wesley
item Fritz, Bradley
item Bagley, William -
item Kruger, Greg -
item Henry, Ryan -
item Czaczyk, Zbigniew -

Submitted to: Journal of ASTM International
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: November 1, 2013
Publication Date: June 18, 2014
Citation: Hoffmann, W.C., Fritz, B.K., Bagley, W.E., Kruger, G., Henry, R., Czaczyk, Z. 2014. Effects of nozzle spray angle on droplet size and velocity. In: Sesa, C., editor. Pesticide Formulation and Delivery Systems: 33rd Volume, Sustainability: Contributions from Formulation Technology, STP 1569. ASTM International: West Conshohocken, PA. p. 151-173. doi: 10.1520/STP156920120131.

Interpretive Summary: Spray applicators must balance flowrate, spray pressure, and nozzle type and setup to deliver their agrochemical in the right droplet size for their particular needs. This work determined the spray exit angle and droplet velocity from three different flat fan nozzles at three different spray pressures. In order to reduce airshear on spray droplet that leads to small, driftable droplets, applicators are advised to use nozzles with the smallest exit angle and use higher spray pressures. The data presented will allow applicators and researchers to select the nozzle and operating conditions that best suit their spraying needs.

Technical Abstract: Spray applicators have many choices in selecting a spray nozzle to make an application of an agricultural product. They must balance flowrate, spray pressure, and nozzle type and setup to deliver their agrochemical in the right droplet size for their particular needs. Studies were conducted to determine the spray exit angle and droplet velocity from three different flat fan nozzles (80º, 40º, and 20º) at three different spray pressures (140, 280, and 420 kPa). Each combination of nozzle and pressure was evaluated in a wind tunnel with airspeeds of 35.7, 53.6, 62.6, 71.5 and 80.5 m/s. At the nozzle exit, droplet velocities for the three nozzles tested were approximately 14, 20, and 25 m/s (~30, 45, and 56 mph) for spray pressures of 140, 276, and 415 kPa (20, 40, and 60 psi), respectively. Droplet velocities were constant across the entire flowfield measured with airstream speed of 35.7 m/s (80 mph), but as the airstream speed increased, droplets at the end of the spray sheet were quickly accelerated. The data presented will allow applicators and researchers to select the nozzle and operating conditions that best suit their spraying needs.

Last Modified: 9/23/2014
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