Design of the key components and optimization of the operating parameters for shielded boom sprayers

In order to address the problems of non-uniform droplet deposition and substantial drift loss during pesticide application on densely planted strawberry plants grown on wide ridges, a Shielded anti-drift spray boom was designed. A CFD model was constructed to simulate the airflow inside and outside the cover, and the effects of different cover widths on internal flow characteristics were analyzed to determine the optimal structural configuration. The simulation results indicated that the airflow inside the cover moves smoothly along the inner wall in a direction opposite to the sprayer’s travel, forming an accelerated airflow zone at the rear lower edge of the cover. The downward-tilted airflow enhances droplet transport toward the canopy surface, while the vertical velocity component decreases with increasing cover width. A cover width of 50 cm produced the highest vertical velocity, which facilitated effective droplet deposition and reduced off-target drift. To further optimize the operating parameters and investigate the effects of spray angle, spray flow rate, and nozzle spacing on droplet deposition on strawberry leaves and stolons, this study conducted a Box–Behnken response surface experiment using artificial strawberry plants. The results showed that spray flow rate, spray angle, and nozzle spacing significantly affected leaf deposition, while flow rate had a notable influence on stolon deposition. The optimal operating parameters were a flow rate of 0.895 L/min, a spray angle of 30°, and a nozzle spacing of 35 cm, yielding deposition amounts of 4.16 µL/cm² on leaves and 0.12 µL/cm² on stolons, with coefficients of variation of 17.49% and 46.11%, respectively. Compared with the conventional boom sprayer in terms of anti-drift performance, the shielded sprayer had better anti-drift effect, which can effectively reduce the aerial drift of droplets by about 88.5% and the ground drift by about 68.6%.