Study On Prediction Of Droplet Deposition For Orchard Air-assisted Sprayer

The efficacy of air assisted sprayers depends on the target characteristics and parameters of the spraying system.Most of the researches on the interaction mechanism of droplet and target are based on the static field crop leaves at home and abroad,which have some limitations.This article aims at studying the deposition state of the sprayed droplets attached to the dynamic target leaves.By integrating the air assisted spray operation parameters and characteristics of the target fruit leaves,the interaction mechanism of the main factors of air assisted spraying on droplet deposition is investigated,along with obtaining the behavior and energy variation law during the interaction of droplet attached to the dynamic target leaves and leaf surface.The model for predicting the droplet deposition state of air assisted spray and the optimal decision-making model for the parameters of air assisted spray operation were constructed to fuse the morphological characteristics of leaves and the surface properties of the leaves.This provided a theoretical basis for proposing a new research method for the deposition behavior of atomized spray droplets.1)A prototype of an axial-flow air-assisted sprayer was manufactured,an axial-flow air delivery test platform was set up,and the axial flow distribution characteristics of the test platform were tested;the particle sizes of the droplets sprayed on nozzles of different particle sizes were measured.The velocity of the droplets in the airflow field is sent by the wind.2)Based on the convolution integral method,the leaves aerodynamic response equation under non-period excitation was established and validated by laser non-contact dynamic measurement system.The instantaneous aerodynamic response velocity of the target leaf was calculated from the target leaf size,initial leaf inclination,leaf aerodynamic response stiffness,and wind speed at the target leaf.3)Experiments were conducted on the deposition of droplets with different characteristic target leaves,and the results of droplet deposition tests were regressed and analyzed.A model was established to construct the relationship between the sliding work of leaf surface for droplet and the roughness factor of leaf surface,the contact angle of leaf surface and the leaf inclination angle.The critical particle size model of droplet was established based on the law of conservation of energy.4)High-speed imaging method was used to observe the droplet deposition behavior,and the droplet coverage rate corresponding to different deposition states of the foliar droplets was deduced;the Response Surface Method analysis of the air assisted variable spray test data to establish the relationship between the sliding work of leaf surface for droplet and deposited droplet dynamic energy.The model for predicting the droplet deposition state of the air assisted spray and the optimal decision-making model for the air assisted spray operation parameters were constructed.