SYMPOSIA PAPER Published: 01 April 2025
STP165220240005

Experimental Measurement of Diameter-Resolved Transport of Droplets in a Low-Speed Wind Tunnel

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As most formulated agricultural products are applied in the field via spray application, understanding and controlling the transport of the spray droplets is critical for maximizing the utility of the applied products and minimizing external effects of the application beyond the target field. Droplet diameter has long been known to be a key factor in determining the potential of sprays to migrate off target during application; however, there has been little experimental study of this transport on a diameter-resolved basis. While physics-based, analytical models exist that can predict the motion of droplets on a diameter-resolved basis, historically experimental measurements of spray transport have focused on measuring the average motion of polydisperse droplets generated via conventional sprays. Herein a novel measurement is presented that allows for the transport characterization of a freely falling droplet subject to a horizontal wind condition. These droplets were produced by a combination of a single-droplet generator tuned to release droplets with average diameters of 788 and 702 μm and a monodisperse-droplet generator producing droplets with diameters of 250 and 154 μm. The droplets were released at heights ranging from 1.5 to 0.25 m within a low-speed wind tunnel operating between 2 and 10 m/s. The droplets were loaded with a dye, and the resulting deposition locations were recorded, allowing for a reconstruction of the droplet trajectories. These trajectories were compared with a simple kinematic simulation of the droplets to identify key transport mechanisms for the droplets on a diameter-resolved basis.

Author Information

Fredericks, Steven, A.
Winfield United, River Falls, WI, US
Massie, Sawyer
Winfield United, River Falls, WI, US
Pothos, Ioannis
Aerospace Engineering Department, University of Minnesota, Minneapolis, MN, US
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Details
Pages: 31–46
DOI: 10.1520/STP165220240005
ISBN-EB: 978-0-8031-7752-9
ISBN-13: 978-0-8031-7751-2