Research And Analysis On The Performance Of Spray System Of Agricultural Aircraft

Although our country has developed a related test methods and specifications about the use of fixed wing aircraft in plant protection presently, it is not perfect enough on small unmanned aircraft, lacking corresponding standard and specifications.In this thesis, we will make experimental research on the spray system with the flight platform of NH-8 agricultural aircraft from Henan Agricultural University Mechanical and Electrical Engineering College. The research is designed according to the factors which influence the quality of spray to decide the type of nozzle and the best operation parameter combination. It can provide valuable reference about the establishment of test methods and instruction on small agricultural aircraft.The main researching contents are as follows:(1)We analyze the structure parameters and load capacity of the aircraft anddesign the spray system reasonably, completing initial design of the spray system.The following works are done: selecting and installing the power of spray system,designing and installing the tank and selecting connecting piping components. Wealso analyze the influence of different height on spray range.(2) We use comprehensive test-bed to simulate the spray system of NH-8agricultural aircraft and analyze the influence of different pressure on atomization angle and fog distribution. Finding that under scope of the pressure from 0.2MPa to 0.4MPa, the atomization angle’s change is not obvious. But wholly speaking, experimental result shows that atomization angle increases with the nozzle diameter. We also find that the amount of fog between two nozzle is more than other area and coefficient of variation differs from pressure. But every nozzle’s coefficient of variation has a minimum, under which pressure we get the best distribution. We finally decide 0.3 MPa as the working pressure.We find that the influence of spray height on the size of the diameter is not obvious and the droplets diameter are bigger with the size of the nozzle, so we think the size of nozzle has a primary impact on the average volume diameter. The droplet under the nozzle LICHENGvp110-015 shows a good penetrability according to the best biological particle theory, and easily be absorbed by most of the prevention and control of crops and pests. So we choose this type of nozzle as working spray nozzle for field test.(3) We analyze the influence of flight parameters on spray deposition effect with the agricultural aircraft taking the finely designed spray system. We plan specific experiment district and set up sampling card to gather up the droplet under different spray height and flying velocity. Tracer is used to test the concentration of droplet and we use coefficient of variation method to evaluate the uniformity. We find that spray uniformity is negatively associated with spray height and flying velocity.Comprehensively thinking experiment data, we find that when spray height is 1.5 m, the velocity is 3 m/s, variation of fog distribution coefficient is the minimum value, under which condition we get the best deposition; this conclusion can be used to instruct guidance at actual production application.