Study On Deformation Of Cotton Canopy Stems And Leaves And Performance Test Of Droplet Deposition Under Assisted Airflow

At present,pesticide spraying is the main method to control pests and diseases,but the effective utilization rate of pesticides is only 30%,caused a serious waste of pesticides.Modern agronomy requires rational close planting to increase yield,but close planting crops grow in the middle and late stages,forming a canopy with high canopy density,although the rate of soil erosion decreased at this time,the deposition attenuation in the middle and lower layers of plant,it resulted in poor uniformity of spraying and low effective utilization rate.Droplet clouds from sprayer nozzles deposited on the plant surface were first intercepted by dense surface leaves.Unintercepted droplets continue to penetrate inward,but the amount of fog droplets began to decrease,and the deposition rate of fog droplets in the plant interior was much lower than that in the plant surface.Therefore,the canopy with high canopy density becomes the biggest obstacle to the penetration of fog droplets.This paper mainly takes the air-assisted spray with high canopy density as the engineering background,selecting cotton with high canopy density from flowering and boll stage as typical crop.The deformations of cotton canopy branches and leaves under assistant airflow and the effect on the deposition of fog droplets in crops were studied.The specific content is as follows:(1)Test on bending deformation of cotton stems and leaves under assisted airflowWith the bending deformation test of cotton stalk and leaf under assistant airflow,using high speed camera and picture analysis technology,the relationship between wind speed of assistant airflow and bending deformation of stems from different parts was analyzed and the relationship between wind speed and leaves with different acreage was studied.The curve of relationship between wind speed and bending deformation of stem and leaf was plotted and the fitting formula of leaf deformation and stem bending deformation was solved.(2)Finite element analysis of bending deformation of cotton stems and leaves under assisted airflowA method of simulating bending deformation of stem and leaf by simulation calculation is presented.The deformations of stems at different parts and leaves of different acreage at different wind speeds were obtained by using ANSYS Workbench finite element analysis software.By comparing the simulation results with the physical test results,the results show that the simulation results of the bending deformation of stems and leaves under different wind speeds are consistent with the experimental results,which provides a finite element analysis method for the future study of the bending deformation of stems and leaves.(3)Establishment of cotton plant test modelReferring to foreign D.Dekeyser and others using artificial trees to compare the deposition quality of seven kinds of orchard spray application technology in trees,the plant models were built according to the growth parameters of real plants for us to successfully carry out experiments.According to the growth structure of cotton at flowering and boll stage,by applying 3/8 growth rule,referring to parameters of main stem,leaf and branch length,selecting appropriate model materials,the cotton plant model was established.(4)Study on the effect of assisted airflow and stems and leaves Deformation on droplet depositionThree experimental schemes were designed by decoupling method to study the deposition law of fog droplets in crops under the effects of assistant airflow,bending deformation of stem and leaf,and the combination of the two.By decoupling method,the effects of assistant airflow and deformation on deposition uniformity and effective utilization rate are analyzed respectively.Comparing the whole deposition amount of fog droplets and the deposition amount of each layer in the plant under three schemes,the deposition rule of fog droplets was studied.By comparing the effects of the two methods on deposition uniformity and effective utilization rate,the results show that deformation can improve the uniformity of droplet deposition,assistant airflow can improve the effective utilization rate of droplets.