Zheng He, Sun Hao, Cao Yubin, Lv Xiaolan, Wang Chaoxi, Chen Yunfu, Yu Hongfeng, Qiu Wei
College of Engineering/Key Laboratory of Intelligent Equipment for Agriculture of Jiangsu Province, Nanjing Agricultural University, Nanjing, 210031, China.
Institute of Agricultural Facilities and Equipment, Jiangsu Academy of Agricultural Sciences, Nanjing, 210014, China.
Plant Methods. 2023 Oct 31;19(1):116. doi: 10.1186/s13007-023-01082-2.
Although previous studies on the droplet deposition behaviour of rice leaves have modelled the leaves as flat surface structures, their curved surface structures actually have a significant effect on droplet deposition.
In this paper, the statistical distribution of the coordinate parameters of rice leaves at the elongation stage was determined, computational fluid dynamics (CFD) simulation models of droplet impact on rice leaves with different curvature radii were built, and the effect of leaf curvature radius on the deposition behaviour and spreading diameter of droplets on rice leaves was studied using validated simulation models. The results showed that the average relative errors of the CFD simulation models were in the range of 2.23-9.63%. When the droplets struck the rice leaves at a speed of 4 m/s, the 50 μm droplets did not bounce within the curvature radii of 25-120 cm, the maximum spreading diameters of 200 and 500 μm droplets that just adhered to the leaves were 287 and 772 μm, respectively. The maximum spreading diameters of 50, 200, and 500 μm droplets that just split were 168, 636, and 1411 μm, respectively. As the curvature radii of the leaves increased, the maximum spreading diameter of the droplets gradually decreased, and droplet bouncing was more likely to occur. However, a special case in which no significant change in the maximum spreading diameter arose when 50 μm droplets hit a leaf with a curvature radius exceeding 50 cm.
Splitting generally occurred for large droplets with a small curvature radius and small tilt angle; bouncing generally occurred for large droplets with a large curvature radius and large tilt angle. When the droplet was small, the deposition behaviour was mostly adhesion. The change in spreading diameter after stabilisation was similar to the change in maximum spreading diameter, where the spreading diameter after stabilisation greatly increased after droplet splitting. This paper serves as a reference for the study of pesticide droplet deposition and its application in rice-plant protection.
尽管先前关于水稻叶片上液滴沉积行为的研究将叶片模拟为平面结构，但它们的曲面结构实际上对液滴沉积有显著影响。
本文测定了伸长阶段水稻叶片坐标参数的统计分布，建立了不同曲率半径的液滴撞击水稻叶片的计算流体动力学（CFD）模拟模型，并使用经过验证的模拟模型研究了叶片曲率半径对水稻叶片上液滴沉积行为和铺展直径的影响。结果表明，CFD模拟模型的平均相对误差在2.23 - 9.63%范围内。当液滴以4 m/s的速度撞击水稻叶片时，50μm的液滴在25 - 120 cm的曲率半径内不会反弹，刚附着在叶片上的200和500μm液滴的最大铺展直径分别为287和772μm。刚分裂的50、200和500μm液滴的最大铺展直径分别为168、636和1411μm。随着叶片曲率半径的增加，液滴的最大铺展直径逐渐减小，并且液滴更易发生反弹。然而，当50μm液滴撞击曲率半径超过50 cm的叶片时，出现了最大铺展直径无显著变化的特殊情况。
曲率半径小且倾斜角小的大液滴一般会发生分裂；曲率半径大且倾斜角大的大液滴一般会发生反弹。当液滴较小时，沉积行为大多为附着。稳定后的铺展直径变化与最大铺展直径变化相似，其中液滴分裂后稳定后的铺展直径大幅增加。本文为农药液滴沉积研究及其在水稻植保中的应用提供参考。
