Design And Experimental Study Of Spray Test Platform Based On Spiral Air-assisted

Pests and diseases are often the direct factors that affect the yield of fruit trees and the quality of orchard products.At present,most of the commonly used mobile plant protection machinery adopts high-volume leaching spray,which results in uneven deposition of fog droplets in the canopy and less than 20% of the liquid medicine deposited on fruit trees,resulting in a large amount of pesticide loss and environmental pollution and pesticide waste.In this paper,aiming at the problems of poor atomization effect,low penetration and low deposition rate of fog droplets in spray operation,a set of air feeding device composed of bellows and spiral tuyere jacket was designed and installed on the test platform.The centrifugal fan is selected as the air flow auxiliary device.The high-pressure air blown out tears the fog drops,refines the fog drops and improves the penetrability.Under the action of the air flow,the height of the spray operation and droplet deposition can be greatly improved.The spiral tuyere sleeve is equipped with spiral blade,which can turn the high-pressure direct current wind from the air duct into spiral wind and improve the adhesion rate of the liquid medicine on the back of the blade and the utilization rate of the liquid medicine.Modeling and simulation optimization of key working parts of air-assisted spray were carried out by three-dimensional drawing,three-dimensional modeling and computational fluid dynamics(CFD).The test platform was designed,modeled and selected.The main research contents and conclusions are as follows:(1)According to the existing problems of spray technology,such as: the back of the blade is not easy to be attached to the liquid,the difference between the positive and negative sides of the blade is large,and the diameter of the droplet is large,a spiral tuyere sleeve with simple structure,easy dismantling and manually installed on the draft tube is designed,and the wind direction is spirally twisted through the action of the spiral piece,so that the liquid can be attached to the back of the blade.The structure of the bellows is designed and optimized.Through three-dimensional modeling and multiple simulation and optimization,the bellows without eddy current and uniformly distributed wind pressure are finally selected.The effects of the inlet velocity,shape and position on the velocity,pressure and trajectory of the flow field were investigated.The simulation results show that the design of the spiral tuyere can greatly improve the outlet wind speed and reverse the direction of the wind to meet the needs of spray operation.(2)The overall design and three-dimensional modeling of the test platform with air-assisted auxiliary function were carried out,and the working components and other components in the air-feeding auxiliary system and the liquid-liquid conveying system were selected and designed to ensure the test platform can work efficient and stable.Through the force analysis of the different installation schemes of the spiral tuyere,the scheme two with the smaller force of the bolt is selected as the processing scheme,and the installation method of the spiral tuyere sleeve is fixed on the air supply cylinder by six sets of bolts to prevent the installation.Under the increasing wind pressure,the spiral tuyere and the blower are forcibly separated.The construction of the test platform was completed according to the design drawing.(3)The static field simulation experiment was carried out by using the vertical droplet distribution instrument,and the statistical analysis software SPSS was used to analyze the test data,and the fan speed,the spray pressure,the spiral tuyere sleeve and the spiral tuyere were not explored.The influence of liquid deposition amount and liquid deposition distribution law;also explored the influence of the interaction between the two operating conditions of the spiral tuyere and the fan speed and spray pressure on the droplet deposition.(4)With the tractor as the power,the actual field test was carried out,and the operation data under the two working conditions of the spiral tuyere were obtained.The data shows that when the spiral tuyere is not installed,the coverage of the droplets is 79.3%,the difference between the positive and negative sides of the leaves is 11.6%,and the diameter of the droplets is 186.08?m.After the spiral tuyere is installed,the coverage rate of the droplets is increased to 80.65%,the difference between the positive and negative chemical solution adhesion rate decreased to 9.6%,and the median diameter of the droplet volume decreased by 21.6%.Therefore,the test results show that the design and application of the spiral tuyere improves the utilization rate of the pesticides,refines the diameter of the droplet,improve the spray operation effect and improve the spray quality.