| In 2016,kiwifruit planting area reached 2 million 960 thousand mu in China,yield reached 2 million 370 thousand tons,which reached nearly 1/3 of the world total.At present,kiwifruit planting pattern was the scaffolding,the pressure spray used for orchard spraying was poor in uniformity of droplets and limited in spray distance,the wind sent sprayer can refine droplets again,but the problem was difficult to control,the droplet drift seriously.Therefore,under the premise of ensuring spray efficiency and improving atomization quality,studying the method of two-phase intensive dosage,developing efficient spraying system suitable for kiwifruit orchard,had the practical significance to enhance the efficiency and improve the quality of atomization spray.In this paper,the water-air two-phase atomizing spraying method introduced kiwifruit plant protection application.Analysis of the atomization characteristics of two-phase nozzle,control parameters and optimization method of water-air two-phase spray technology,designed the control system of two-phase atomization spraying.Combined with the kiwifruit orchard structure,optimization of the two-phase atomization system of controlling strategy.On the basis of experimental research,the micro-cultivator was used as the dynamic walking chassis,made the water-air two-phase sprayer and completed the field spraying operation test,verified the validity of the two-phase spraying method in kiwifruit orchard operation.The main research contents are as follows:(1)Spray characteristics of water-air two-phase nozzle: built the atomization test system of water-air two-phase nozzle,completed test of spray angle,distance,flow and other parameters.Ensured that the two-phase fan nozzle,in the whole range of water flow,can improve the directivity and the adhesion effect of droplet,and can effectively prevent drift.By adjusting the water flow and air pressure,spraying water can be continuously adjusted in the range of 0~120ml/s,and can adapt to the condition of variable spray frequently,and the nozzle diameter was 1.2mm,so it had excellent anti clogging performance.(2)Control method and optimization of water-air two-phase atomization: for the three types of two-phase nozzles,fan-shaped nozzle,wide-angle circular and circular nozzle,built the test platform of two-phase atomization characteristics with the aluminum,experimentalstudy on the spray angle and distance,flow and pressure atomization characteristics.In the water pump pressure 12 V,the pressures changed through the air path in the range of1.5-4.0bar value,obtained the spray angle and distance,water-air flow rate,water-air pressure.Through the analysis of the spray angle and distance between the air pressure throughout the experiment,gained the optimal value of the pressure spray.The test showed that the fan-shaped nozzle uniformity and spray distance were better than that of wide-angle circular nozzle and circular nozzle,the air pressure valued in the 2.5bar,had the optimal atomization characteristics of two-phase nozzle,in the process of atomization nozzle flow type,air pressure and water flow were inversely proportional,the air pressure increased,the water flow became smaller.(3)Study on optimal control of water-air uniform orientation based on two-phase atomization: based on the atomization characteristics of test platform,built the two-phase atomization control system,used V type spray tank,spray tank inclined angle was 5.09 degrees,V groove angle was 36.6degrees,V tank and spray atomization characteristics together formed the uniformity test the platform,with uniform oriented,according to the jet size of optimal parameters of atomization characteristics,tested the spray uniformity with different pressures and different nozzle heights,atomization control strategy of two-phase nozzle.The test showed that optimal uniformity of air pressure at 2.5bar,the height of nozzle at 0.5m optimal uniformity.(4)Development and performance test of kiwifruit sprayer.According to 3.0m,2.0m rows spacing Meixian kiwifruit orchard,designed the walking chassis type sprayer with kiwifruit orchard for micro-cultivator.The length of sprayer 1.73 m,width 1.0m,height 1.45 m.Through the reasonable selection and arrangement of air compressor,water pump and spray bracket,tested application for indoor spraying quantity.Test showed that without the pressure of spray volume was about 0.3L/min,a pressure of about 0.21L/min,and outdoor artificial target test,the running speed of 1.0m/s sprayer,working width was 3.0m,the spray pressure was 2.5bar,the spraying rate was 0.21L/min,the test showed that the droplet distribution coverage rate in 13% to 15%,research showed that sprayer with two-phase spray can basically meet the spray demand. |
