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Assessing a VOF-to-DPM Computational Fluid Dynamics Technique for Expediting Advanced Agricultural Nozzle Designs in Applications for Enabling Real-Time Spray Drift Mitigation
Off target application has plagued agricultural spraying for decades with wind being one of the greatest impacts on unwanted droplet movement. Generally, there is a trade-off between mitigating the potential for off target movement and maintaining label requirements. Weather compensating control logic for a Modified Variable Orifice (MVO) spray nozzle was accomplished to produce a method that allows for shifting the coarseness of the atomization profile for increasing wind speeds while still maintaining desired label rate and droplet category. Additionally, to expand the potential operational window of the MVO, a deep investigation into using modern computational fluid dynamics (CFD) simulation methods was performed. The method utilized, Volume of Fluid-to-Discrete Phase Model (VOF-to-DPM), allowing any arbitrary geometry to be input with the multiphase interaction being evaluated during liquid sheet formation, transition into particles based on user specifications, tracked as discrete particles, with particle distribution information provided as a result. Information from this distribution was directly related to current agricultural spray nozzle performance and characterization methods (i.e., laser diffraction in a wind tunnel and spray pattern uniformity performance). Analysis of the method on known nozzle geometries allowed for a validation of relative change between a single geometry change (fan degree), where the relative change was indeed similar between simulated nozzles and real-life nozzles (simulated Dv50 values for a TeeJet 8003VS and XR110003VS were 33.9% and 58.5% respectively of wind tunnel evaluated Dv50 values). The results of this work will have a direct impact on future nozzle design and expedited iterative design for enlarging the operational window of variable orifice nozzle designs and/or providing more precise control on nozzle droplet size production.
Marx, Samuel E, "Assessing a VOF-to-DPM Computational Fluid Dynamics Technique for Expediting Advanced Agricultural Nozzle Designs in Applications for Enabling Real-Time Spray Drift Mitigation" (2022). ETD collection for University of Nebraska - Lincoln. AAI29166752.