DROPLET DEPOSITION BEHAVIOR ON A PEAR LEAF SURFACE UNDER WIND-INDUCED VIBRATION

Pear frees, a kind of fruit tree prone to diseases and insects, are sprayed 7-8 times a year in northern China and 8-10 times a year in the hot and humid areas of southern China. Air-assisted spraying is also the mainstream application technique for pear frees at present. To study the deposition behavior of droplets on pear leaves under the effect of air flow, the movement states of fluorescent droplets at different initial leaf angles and different leaf positions were measured with a high-speed camera. Based on the combined effect of the microstructure and the vibration of pear leaves, the factors and limiting conditions affecting the vibration and spreading of droplets were analyzed, and a mathematical model of the vibration and spreading of droplets on pear leaves was constructed. The experiment showed that the degree of influence of each factor on the velocity and acceleration of the droplets is in turn the inflow velocity, the drop position and the initial leaf angle. For pear hydrophilic plants, it is necessary to meet both conditions that the droplet velocity is less than the critical velocity of 1.1 m/s and the droplet acceleration is less than the critical acceleration of 20 m/s(2) so that the droplet can deposit on the leaf surface. An inflow velocity of 7 m/s better facilitates droplet deposition and spreading.