| China’s orchard area ranks first in the world,and fruit planting area is increasing year by year.At present,orchards mainly use the way of spraying pesticides to control orchard diseases and insect pests,20%to25%of the output of agricultural products benefit from the use of pesticides,fruit trees need to spray pesticides 8 to 15 times a year,and the huge demand for orchard diseases and insect pests control puts forward higher requirements for orchard plant protection machinery.At present the orchard control efficiency is the highest and the effect of the best machinery for orchard pneumatic sprayer,but due to the actual operation parameters set unreasonable,pesticide drift serious phenomenon is very common,resulting in low utilization of pesticides,serious environmental pollution,energy consumption and so on.In order to achieve the goals of energy saving,pesticide consumption reduction,and uniform droplet deposition,this thesis designed a tower-type air delivery orchard spray test bench,and designed the experiment with the droplet penetration rate and deposition amount as indicators to optimize the application parameters.To provide a reference for the selection of actual operating parameters.The main research contents and conclusions are as follows:(1)Combined with the typical orchard planting model in China and the canopy characteristics of the spindle-shaped fruit trees,a tower-type air-blast spray test bench suitable for the spray operation of the spindle-shaped fruit trees was researched and designed.Mainly design the air delivery system and spray system,determine the fan air volume Q=9500m~3/h,fan impeller diameter D=600mm,blade number Z=9,nozzle number N=12;In addition,the test bench uses LiDAR to detect the canopy The PID control algorithm is used to control the flow of the spray system.The speed of the fan and the speed of the diaphragm pump are adjusted by the frequency converter to control the motor.(2)The accuracy of radar detection canopy is verified,and point cloud data and leaf area index data are fitted and analyzed,and finally the LAI prediction model of front scan and back scan is fitted,and the F test results of the model show samples There is a significant difference between them,and the goodness of fit of the model is greater than 0.9.(3)Measure and analyze the wind speed at each point of the air outlet and canopy of the tower air-sending sprayer.The measurement results show that the wind field distribution of the air outlet of the tower-type air-blast sprayer is similar to the spindle shape,which is suitable for the air-blast spray operation of the spindle-shaped fruit tree.Three sets of rotation speeds of 1600 r/min,2200 r/min and2800 r/min were selected for canopy wind field measurement.The results show that the wind field in the canopy can meet the requirement of carrying fog droplets to penetrate the canopy of fruit trees.(4)Using the droplet penetration rate and the number of deposits as indicators,the matching relationship between the canopy of different leaf area indexes and the wind speed and pressure during the air-blast spray process was studied.And through response surface analysis,the wind-driven application parameter model was established,in which the CV value prediction model P value<0.05,R2=0.8298,RAdj=0.611;the fog droplet number prediction model P value<0.0001,R2=0.9835,RAdj=0.9622,And provides the actual operation process through Matlab,according to the application parameter model to solve the specific application parameters of the method steps,and field trials,the test results of the maximum prediction error of CV value is 9.26%,the maximum prediction error of the number of deposits The value is 9.28%,indicating that the method can be applied to the variable pesticide application system as the decision basis of the variable system. |
