Design And Test Of Electric Air-Driven Tobacco Plant Protection Machine And Its Key Components

Our country is a big country of tobacco planting and production.Tobacco is a leaf cash crop.The quality and yield of tobacco leaf directly affect its economic value.At present,most tobacco farmers in tobacco-growing areas still use backpack sprayers or highculm crop general-purpose sprayers to carry out plant protection operations in large capacity.These backward operation methods not only increase the labor burden and planting cost of tobacco farmers,but also cause the unequal distribution of medical liquid between front and back tobacco leaves and between upper tobacco leaves and middle and lower tobacco leaves.Aiming at the problems of mechanization,low degree of intelligence and unequal distribution of liquid medicine in the operation process of tobacco plant protection machinery.Based on the concept of combining green environmental protection with agricultural machinery and agronomy,this paper understands the actual planting characteristics of tobacco in Henan tobacco area based on field research,summarizes the advantages and disadvantages of existing plant protection machines,and proposes the idea of combining ultrasonic atomization technology with traditional atomization.This paper aims to design and develop an electric air-driven tobacco plant protection machine by combining theoretical calculation,numerical simulation and experimental verification.The main research contents are summarized as follows:1.The overall design scheme of electric air-driven tobacco plant protection machine was determined after preliminary literature review and field research.The key parts of plant protection machine,such as ultrasonic atomization generator,air delivery system,spray system,wheel pitch and spray height adjustment device,were designed and selected.The Solidworks modeling software was used to conduct three-dimensional modeling,size determination and virtual assembly of key components,and the whole machine model of electric air-driven tobacco plant protection machine was obtained.2.Numerical simulation was carried out on the air delivery system of the electric air delivery tobacco plant protection machine.Fluent software was used to analyze the changes of the internal flow field and the distribution of the external flow field of the nozzle,and the rationality and effectiveness of the numerical simulation model was verified through subsequent tests.The numerical simulation results show that the air distribution is uniform on both sides of the guide column in the nozzle,and the overall air distribution is uniform at the section of the outlet of the nozzle.The follow-up test results show that the distribution trend of air velocity at the section of the nozzle outlet is consistent with the numerical simulation results,and the average air velocity has little difference with the numerical simulation results and conforms to the design requirements.3.Measurement of spray amplitude and spray volume,uniformity test and droplet deposition characteristic test based on simulated target were carried out for the trial-produced prototype of electric air-fed tobacco plant protection machine.It is determined that the spray amplitude of the prototype and the spray volume of the four nozzles of the prototype are basically consistent and meet the theoretical spray volume requirements.The effects of different spray pressure,wind speed and prototype speed on spray uniformity were investigated.The variation coefficient of the number of fog drops decreases with the increase of spray pressure and wind speed within a certain range,and the uniformity becomes better.The increase of the prototype traveling speed does not affect the uniformity of spray,but the number of fog drops decreases accordingly.The influence of different spray pressure,wind speed and prototype speed on droplet coverage rate was investigated.It is found that the increase of spray pressure basically does not change the maximum fog drop coverage rate,the increase of wind speed will reduce the maximum fog drop coverage rate,and the increase of prototype speed will reduce the overall fog drop coverage rate.The coverage rate of fog drops with the highest sampling height decreases rapidly with the increase of sampling distance,the coverage rate of fog drops in the middle area of sampling height tends to be stable,and the coverage rate of fog drops with the lowest sampling height is pulsating.With the increase of sampling distance,the peak area of fog drop coverage will shift downward.4.Field experiments were carried out on the prototype of the electric air-driven tobacco plant protection machine.The test results showed that the ultrasonic atomizing device was turned on when the prototype of the electric air-driven tobacco plant protection machine was operating,and the average adhesion rate of the tobacco leaf was 78.12% on the front side and52.08% on the back side.With the ultrasonic atomizing device closed,the average drug liquid adhesion rate of tobacco leaf was 71.87% on the front side and 48.95% on the back side.All in line with the national standards for spraying.