Design And Research Of Airborne Atomization System For Precision Aerial Spraying

Aerial spraying has the characteristics of high efficiency,strong terrain adaptability and fast reaction speed,which compensate for the deficiency of traditional spraying machinery and manual operation.In recent years,it has developed rapidly in the application of agricultural plant protection in china.But as a result of aerial spraying equipment is far from the target,spraying droplets are influenced by environmental airstream,temperature and humidity,and the droplet diameter is the important factor affecting drift and deposition.The unreasonable droplet diameter leads to the serious drift and cause people and animal pollution to the non-target area,which affects the deposition of the target area and finally affects the application.In order to solve the problem of precise control of droplet diameter variables in aerial spray,this dissertation researches airborne atomization system for precision aerial spraying by helicopter and fixed wing aircraft.The specific work is as follows:(1)Research on the theory of droplet crushing and the atomization method of airborne application,according to the manned helicopter high flight speed,altitude and flow rate,combined with the technical requirements of controllable droplet diameter,the atomization project of airborne atomization system for precision aerial spraying was determined.According to the project and the functional requirements of the system,the general design and system composition of airborne atomization system for precision aerial spraying were determined.(2)Study on airborne atomization system for precision aerial spray,including device selection,hardware circuit design,control program design and control parameter setting.Complete the selection of main control system,detecting unit and electronic governor,and the optimization of centrifugal atomizer,finish the circuit design of hardware.Trial-and-error method is used to get controlled parameters,the atomizer rotating speed is 700?4000 r/min,k_p=0.2,k_i=0.02,the atomizer rotating speed is 4000?5000 r/min,k_p=0.3,k_i=0.03,the atomizer rotating speed is 5000?6000 r/min,k_p=0.4,k_i=0.03.Complete the design of control program based on the quadratic residual compensation atomization model of electricity.Finally finish the design of airborne atomization system for precision aerial spray.(3)The establishment of quadratic residual compensation atomization model of electricity.With electricity atomizer as the control object,the quadratic regression orthogonal experiment was carried out on the atomization experiment platform to analyze the correlation between the droplet volume median diameter and the wind speed,the flow rate,the atomizer speed,and the droplet diameter model was established.In order to improve the prediction accuracy,a compensation factor was added to establish the first optimized droplet diameter compensation model.To further improve the prediction accuracy,the second residual prediction model was established by machine learning,the second residual prediction model and the first optimized droplet diameter compensation model were superimposed linearly to obtain the quadratic residual compensation droplet diameter model.In order to verify the validity of the quadratic residual compensation droplet diameter model,the model validation experiment and the comparative experiment were carried,the results showed that the maximum deviation predicted by the quadratic residual compensation droplet diameter model was 10.78%,the R~2 between the predicted and measured values of the quadratic residual compensation droplet diameter model was 0.95,which was 0.06higher than the droplet diameter model and 0.05 higher than the first optimized droplet diameter compensation model.In this research,the quadratic residual compensation atomization model of electricity atomizer was obtained by equivalent deformation of the quadratic residual compensation droplet diameter model.(4)The airborne atomization system for precision aerial spraying was built-in the wind tunnel laboratory.The experiments were carried out to verify the effectiveness,response characteristics,universality and atomization characteristics of the system.The results show that the airborne atomization system for precision aerial spraying can achieve the function and operate normally,the response adjustment time of the system is less than 3 s,the steady-state mistake of the rotating speed of the atomizer is less than 1%.For different environment,different electricity rotating atomizer atomized droplets volume median diameter deviation was less than 8?m in diameter,the maximum deviation between the droplet volume median diameter of the atomized and the expected value of the system is less than 12%,the relative span of the droplets is less than 1.4.When the expected value of droplet volume diameter is more than 130?m,the maximum percentage of<100?m droplet does not exceed 20%.