Straight stream nozzles models to support aerial applications

Authors: Fritz, Bradley - Brad

Submitted to: Journal of ASTM International
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/14/2023
Publication Date: N/A
Citation: N/A

Interpretive Summary: Spray drift prevention is a key factor in the development and use of application technologies used in agrochemical pest control, with the spray nozzles providing the most control of the quality of any application. Aerial applications require unique, specially designed nozzles that are able to produce larger droplets while preventing the formation of smaller, drift prone spray sizes. A series of high-speed wind tunnel tests were conducted to characterize the spray quality from two nozzles that produce straight stream spray patterns, with models developed to guide their proper selection and use to achieve user-specified spray sizes. Both nozzles were shown to create sprays with much larger overall droplet size distributions compared to the majority of those commercially available for aerial use. The developed model were shown to fit measured data with a high degree of confidence and were integrated into currently available aerial applications decision management tools that guide their proper selection and use in mitigating off-target damage while ensuring product efficacy.

Technical Abstract: Maintaining operational efficiency while mitigating spray drift potential can be challenging, particularly with modern aircraft that are capable of higher airspeeds. One of the easiest and most effective tools for reducing off-target movement is increasing droplet size, which minimizes the fraction of spray volume containing smaller, drift prone droplets. Proper nozzle selection and use is the first, and most significant step towards improving overall spray characteristics. Two straight stream nozzles typically used in fertilizer banding applications were evaluated for performance when used under aerial application conditions. Both nozzles generally resulted in similar droplet size characteristics when operated in similar conditions, though the H1 4U nozzle tips resulted in slightly larger droplet size distributions overall. The resulting droplet size models were incorporated into a series of computer and smartphone-based user-interfaces that allow for simple inputs of application conditions (i.e. airspeed, spray pressure, and orifice size) with the resulting droplet size characteristics returned to the applicator. With the ever-increasing need for application efficiency through use of higher airspeeds and the critical need to mitigate off-target damage through increased control over placement of applied sprays, it is anticipated that these, and other straight stream nozzles, will find increased use throughout the industry making the availability of these models critical to ensuring successful applications.