An investigation of airflow patterns created by high-clearance sprayers during field operations

Field experiments and computational fluid dynamics (CFD) simulations were carried out to investigate the levels of turbulence that developed in the wake of high-clearance agricultural sprayers. Ultrasonic anemometers were mounted behind the booms of two sprayers to measure local airflow for various treatments of travel speed, lateral location along the booms, longitudinal location behind the booms, and ambient wind conditions. The primary metric used in this investigation was the turbulence kinetic energy (TKE). Significant differences were found in the TKE values for all the factors investigated. CFD modeling was performed to gain an understanding of the incremental contribution of various components of the sprayer to the TKE levels. Simulating the rotation of large agricultural tires indicated some level of turbulence in their wake suggesting they should not be ignored when assessing the wake of the sprayer. Simulation results also suggest that both the geometry of the sprayer and its travel speed influenced the airflow patterns. The investigation of the sprayer tractor with rotating tires revealed a large increase in TKE levels in the wake of the implement when increasing the travel speed from 2 to 8 m/s. The boom created an additional obstruction to the airflow and its own contribution to the levels of TKE, with localized impact where multiple members of the truss structure meet. This research established necessary baseline information and methodologies to support future efforts to better understand the impact of large sprayers operated at high speed.