Optimal Design And Test On The Pre-guided Flow Structure Of Long-rang Air-blast Sprayer

Air-blast spray is internationally recognized as an efficient ground pesticide application technique second only to aerial spray,which preforms good atomization effect and maneuverability,and helps to reduce pesticide usage.Up to now,the research on sprayers mainly focuses on the design and optimization of the air duct and fan structure,the simulation of flow field inside and outside the air duct,the droplet deposition and droplet drift,and there are few studies on the pre-guide flow structure.Based on this,this paper focuses on the effect of the parameters of the pre-guide flow structure on the flow field of the air duct interior and the air-velocity at the wind outlet.The main research contents and results are as follows:(1)Modeling and simulation of the air duct: Based on the structural parameters of the air duct test prototype,established the geometric model of the air duct by Solid Works software;and divide the model into geometric grids via the ICEM CFD software,including three parts;and set different grid sizes for each part,and imported the partitioned grid file into Fluent software for analogue simulation.(2)Reliability test of the numerical simulation model: Adjusted the frequency of the transducer to change the speed of the fan,measured the wind speed of the wind outlet and the pressure value at different positions inside the air duct at different rotational speeds;and preformed comparison analysis and chi-square test between the simulation results and the measured results,the test result indicated: The simulated wind speed at each sampling point of the wind outlet completely conformed to the measured wind speed,the simulated pressure at the sampling point near the wind outlet conformed the measured pressure distribution,which shows the reliability of the numerical calculation model employed in this paper.(3)Pre-guide flow structure design and parameter optimization: The numerical simulation of the pre-guide flow structure and the pre-guide plate is studied by using CFD software,adopted a single factor optimization experiment and a three-factor three-level orthogonal test to study the change of three key structure parameters,including the shape of the pre-guide flow structure,the bending angle and the number of the pre-guide plate,which have effect on the wind speed at the outlet of the air duct and the flow field inside the air duct.The optimized parameters of the pre-guide flow structure are as follows: The pre-guide flow structure shape for a half sphere,the pre-guide plate number for 5,the pre-guide plate of bending angle is 6°.(4)Prototype production and observed test of the pre-guide flow structure and the preguide plate: Tested the long-range air-blast sprayer with optimized pre-guide flow structure,by taking the wind speed and the pressure inside the air duct as evaluation indexes,and evaluated the optimal performance.The experiment results indicated that the average optimization rate of dynamic pressure and total pressure near the air outlet are 5.818% and 4.651%,which at a fan speed of 2926.5rpm,the wind speed optimization percentage is 3.180%.