The Effect of Pesticide Solutions on the Deposition of Bubble-Containing Droplets
The deposition of spray droplets is a critical topic in plant protection. The air-induction nozzle is believed to mitigate spray drift by producing bubble-containing droplets. However, research on the deposition of bubble-containing droplets is limited. In this study, the deposition process of bubbl...
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| Main Authors: | , , , |
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| Format: | Article |
| Language: | English |
| Published: |
MDPI AG
2025-05-01
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| Series: | Agronomy |
| Subjects: | |
| Online Access: | https://www.mdpi.com/2073-4395/15/5/1172 |
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| Summary: | The deposition of spray droplets is a critical topic in plant protection. The air-induction nozzle is believed to mitigate spray drift by producing bubble-containing droplets. However, research on the deposition of bubble-containing droplets is limited. In this study, the deposition process of bubble-containing droplets was investigated using high-speed photomicrography. Three typical pesticide solutions, oil-based emulsions, suspensions, and aqueous solutions were used to produce bubble-containing droplets. Both hydrophilic and hydrophobic surfaces were used as deposition targets. The results indicate that the deposition of bubble-containing droplets can generate a central jet resembling the Worthington jet. All three solutions reduced liquid surface tension, thereby increasing the maximum spreading diameter of bubble-containing droplets. On hydrophilic surfaces, a functional curve describing the maximum spreading factor was fitted based on the dimensionless Weber number (<i>We</i>), expressed as <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><msub><mrow><mi>f</mi></mrow><mrow><mi>max</mi></mrow></msub><mrow><mo>=</mo><mn>0.04</mn></mrow><msup><mrow><mi>We</mi></mrow><mrow><mn>0.508</mn></mrow></msup><mrow><mo>+</mo><mn>3.21</mn></mrow></mrow></semantics></math></inline-formula>. On hydrophobic leaves, the dynamic evolution and retention effects of bubble-containing droplets were analyzed. Suspensions and aqueous solutions exhibited droplet rebound, while oil-based emulsions transitioned from rebound (0–0.2% concentration) to adhesion (0.4–0.8% concentration), with 0.4% identified as the critical concentration for this rebound-to-adhesion transition. Morphological variations during deposition, including rebound, splashing, and fragmentation, were also observed across different solution concentrations. |
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| ISSN: | 2073-4395 |