The Motion of Strawberry Leaves in an Air-Assisted Spray Field and its Influence on Droplet Deposition

Abstract

HighlightsA visualization method for the motion of strawberry leaves in an air-assisted spray field is proposed.Strawberry leaves showed two motion states in different critical velocity ranges of the sprayer airflow.The airflow instability and the turbulence effect are considered important factors for the leaf vibrations.A strawberry leaf azimuth angle in the range of 90° to 270° can provide good deposition with smaller droplets.Abstract. The reasonable motion of crop plants in an air-assisted spray field can improve droplet deposition. Therefore, this study focuses on the motion of strawberry leaves and the droplet deposition mechanism in an air-assisted spray field. First, this study proposes a descriptive method for strawberry leaf motion in an air-assisted spray field and clarifies the important influence of strawberry leaf motion on droplet deposition. Second, an experiment was performed on the motion and droplet capture of single strawberry leaves in multi-position postures in an air-assisted spray field. The results showed that the leaves had two motion states (i.e., low amplitude with low frequency and high amplitude with high frequency) at different airflow velocities and inclination angles, and the critical airflow velocity corresponding to the two motion states was determined to be 8.7 m s-1. When the azimuth angle of the strawberry leaves is in the range of 90° to 270°, a reasonable inclination angle of the airflow and the high frequency and high amplitude vibration state of the leaves driven by the airflow will provide good deposition and canopy penetration of droplets with smaller diameters. Keywords: Air-assisted spray field, Droplet deposition, Motion, Spray, Strawberry leaves.

Resistance characteristics of broad-leaf crop canopy in air-assisted spray field and their effects on droplet deposition

“…To analyze the droplet capture process of crop canopy quantitatively, it was assumed for simplicity that the leaves in each layer of the crop canopy would not overlap and each leaf in each layer would only affect the motion and droplet capture process of the corresponding leaves after the direction of their respective airflow and droplets. In a previous study, combining a droplet capture test of crop leaf motion in the air-assisted spray field and the above theoretical analysis, we found that when the initial azimuth angle of the leaf relative to the assisted airflow was 90°-270°, with the appropriate inclination of the applicator fan being the highfrequency and high-amplitude vibration state of the leaf driven by the assisted airflow greater than the critical wind speed, there were good positive and negative uniform deposition effects on droplets of small diameters (Wu et al, 2021). Therefore, on the premise that the initial azimuth angle of the leaf is known, the droplet capture effect can be analyzed.…”

“…In a previous study, as shown in Figure 2-combined with the relevant research conclusions of Dorr et al-the contact process between droplets and plant leaves was thought to occur in three stages: that is, the pre-contact, spreading, and rebound, sputtering, or deposition stages (Dorr et al, 2016;Wu et al, 2021). Droplets are accelerated by the nozzle injection pressure and sprayer airflow in the pre-contact stage, having initial kinetic, potential, and surface energies, with the total energy being E 1 .…”

“…As leaves are the basic elements of the crop canopy, their motion in the air-assisted spray field constitutes the mathematical basis of relevant theoretical and experimental studies. In a previous study, we proposed a visual descriptive method for leaf motion in an air-assisted spray field, as detailed below (Wu et al, 2021). As shown in Figure 1, the base coordinate system,…”

“…Therefore, the authors conducted related research on the motion characteristics of strawberry leaves in an air-assisted spray field and their effects on droplet deposition (Wu et al, 2021). Efficient droplet deposition of the crop canopy required that when a leaf moved due to the assisted airflow, contact was ensured between the front and back of the leaves and the droplets, and a reasonable state of motion was achieved to ensure effective deposition.…”

An electrical vortex air‐assisted spraying system for improving droplet deposition on rice

“…The use of fine droplet size can increase the deposition of droplets at the base of the canopy, but it will also bring more drift 38 . For crops with sparse canopy, changing the direction angle of airflow can greatly improve the penetration ability of droplets 39 . The canopy opener uses the lever device to disturb the crops so that the droplets can penetrate smoothly, and the canopy base and the back of the leaves are significantly improved 40,41 .…”