Static and dynamic study of the airflow behavior generated by two air assisted sprayers commonly used in 3D crops

• Two types of air-assisted sprayers were evaluated for their airflow configurations under both static and dynamic laboratory conditions. • The use of three-dimensional anemometers enabled the evaluation of the air velocity vector behavior in the sprayers' environment. • Modifying the fan gear-box setting and outlet section resulted in different airflow rates and air outlet velocities. • Application parameters influenced the air velocity vector in both sprayers, exhibiting different behaviors under both static or dynamic conditions. • Equations capable of reliably predicting air velocity were developed for both sprayers. Air-assisted sprayers, which are commonly used for pesticide application in three dimensional (3D) crops, are evolving towards increasingly innovative designs in terms of pneumatic system regulation with the aim of providing an adjusted amount of airflow to the target. As a result, it is currently possible to modify the characteristics of the airflow by remote control from the cab or manually. In this sense, characterizing the behavior of airflow in agricultural sprayers has become crucial to understand how the characteristics of the air velocity vector vary before reaching the crop when the main application parameters change. Therefore, the present study focuses on characterizing the airflow generated by both a multirow and an axial air-assisted sprayer as a function of different configurations associated with both the pneumatic system (fan gearbox position and diffuser air outlet section) and the application conditions (height, horizontal distance and forward speed) with the final objective of obtaining mathematical models to estimate the air speed in the vicinity of the crop as a function of these parameters (pneumatic system configurations and application conditions). Air velocity maps were generated for each sprayer in both static and dynamic situations under laboratory conditions and in the absence of wind. Airflow rate (m 3 h −1 ) generated by the sprayers was first quantified in accordance with the ISO 9898: 2000 standard using a vane probe anemometer. Then, static and dynamic measurements were carried out using a 3D ultrasonic anemometer to analyze module and direction of the air velocity vector for all configurations. Results showed some similarities in the airflow behavior between sprayers under static conditions. As horizontal distance increased, the vertical distribution of airflow became more homogeneous across different heights. Furthermore, the adjusted deflectors of the Twister sprayer and the multirow design resulted in minimal variation in the direction associated with the lower magnitude components of the air velocity vector. As the forward speed increased, main factors had different effects on the response variables among the sprayers. Models with a high goodness of fit when predicting the air velocity module were achieved for both sprayers.