Background: To improve droplet deposition rates at the base of rice, an electrical vortex air-assisted spraying system for smalland medium-sized high-clearance boom sprayers was developed. This system uses vortex airflows to guide droplets to the base of rice and the back of leaves, as well as to increase leaf perturbation and droplet penetration and deposition.Results: The spatial distribution of the airflow field generated by this system and the effects of the canopy on the airflow field were described. An orthogonal experiment was performed in a rice field based on fan speed, auxiliary airflow angle, and spray height as the experimental factors. It was discovered that a fan speed of 4000 rpm, auxiliary airflow angle of 0°, and spray height of 30 cm were optimal for droplet deposition at the base of the canopy. These settings resulted in droplet coverage of 54.5% and 35.9% on the front and back of the leaves, respectively, which are 48% and 104% higher than that on the front and back sides of leaves without an auxiliary airflow, respectively. Conclusion: Compared with the traditional application method, vortex air-assisted application significantly improved the rate of droplet coverage in rice canopy of different area. Hence, vortex air-assisted application enables new approaches and methods for rice crop protection.

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Background The interaction between canopy and droplets is very important in the process of crop spraying. During the actual air-assisted application process, air-mist flow inevitably disturbs the leaves before droplets reaching them, which will also affect the final deposition state of the droplets on the leaf. Currently, researches on the interaction between droplets and the target leaf surface mainly focuses on the deposition behaviour on the surface of stationary target leaves rather than the dynamic leaves. Therefore, the deposition characteristics after the collision between the droplets and dynamic leaves are important for practical application and worth further study. Results Computational fluid dynamics simulations were performed to characterise the surface roughness, contact angle, and mechanical vibration. The interaction platform between the droplet and the vibrating pear leaf was built for experimental verification under laboratory conditions. The simulation results are in good agreement with the experimental results, which revealed the main reason for the droplet spreading and sliding was the inertial force generated by the relative velocity. It also indicated that the pear leaf vibration can improve the deposition of low-velocity and small droplets, which is different from that of static pear leaves. Conclusion The deposition effect of droplets in vibrating pear leaves was investigated. This study also provides a simulation method for the collision between a vibrating leaf and moving droplets, and provides reference for the study of droplet deposition characteristics under the vibration of fruit trees.