Design And Test Of Contact Electrostatic Spray System For Low-altitude UAV

Aerial spray can get rid of terrain restrictions,in complex environments can also be carried out pesticide spraying operations.Compared to ground machinery,aerial spray equipment is not in direct contact with plants,greatly reducing the mechanical operation of the plant damage caused.Electrostatic spray is a new type of spray technology that allows the droplets of pesticide spray to be refined to improve the uniformity of the spray and to allow pesticide droplets to reach the back of the plant leaves that can not be sprayed by conventional spray.The combination of unmanned helicopter spray and electrostatic spray can effectively improve the deposition of pesticides on crops,and improve the spray effect.In this paper,based on the F-50 plant-based unmanned helicopter flight platform,a new type of contact electrostatic spray system was developed.Which achieve the switching between conventional spray and electrostatic spray.At the same time,a CFD simulation model for unmanned helicopter spray field research is established.The experimental study on the wind speed,the amount of spray deposition and the uniformity of the depositional distribution of the rotor wind field is carried out to provide guidance for the electrostatic spray operation parameters of the small unmanned helicopter.Through the actual field experiment,the effect of unmanned helicopter contact electrostatic spraying was studied.The main research work is as follows:(1)Design and verification of aerial contact electrostatic spray systemOn the basis of the existing helicopter system,the principle of contact charge and the specifications of the parts in the spray system,select the appropriate components installed on the existing spray system,composed of unmanned helicopter bipolar contact electrostatic spray system.The results show that the charge-to-mass ratio of the droplet increases with the increase of the voltage and becomes stable after 25 kV.The charge-mass ratio of the droplet is increased with the increase of the voltage and the charge-Which decreases as the spray pressure increases.(2)Unmanned helicopter rotor wind field simulation and testThe rotor model of unmanned helicopter was simulated by CFD technique.Then,the wind speed distribution of the wash-flow field was obtained by F-50 unmanned helicopter underwent wind speed measurement.,And simulation results were compared.The results show that the simulation and experimental results are basically the same,and the model can be used for the research and analysis of the F-50 unmanned helicopter under the wash flow field and the subsequent spray field.(3)Unmanned helicopter spray field simulation and testIn the unmanned helicopter rotor model,the jet source was added and the droplet was simulated by the DPM discrete phase model to simulate the droplet in the rotor wind field.The deposition effect of spray on the ground was obtained by the coupling analysis of gas-liquid two-phase flow at different spray height(1m,2m,3m)and relative flight speed(2m / s,3m / s,4m / s).The deposition effect of the unmanned helicopter electrostatic spray system at the same flight height and flight speed was obtained by the flight sedimentation test in the plain.The results show that the model can be used to study the amount of spray deposition of unmanned helicopter.With the increase of spray height,the amount of spray deposition decreases with the increase of spray height.With the increase of spray height,The rate of increase in spray deposition decreased.(4)Unmanned helicopter electrostatic spray deposition testBased on the F-50 unmanned helicopter platform,the effect of spray deposition on different charging methods is compared.The results show that the deposition amount of non-static spray is basically equal to the deposition amount of contact electrostatic spray,the amount of electrostatic spray The contact charge and the induction charge can improve the uniformity of the aerial spray,and the deposition uniformity of the contact charge is better than that of the induction charge.The pesticide spraying test was carried out on the F-50 unmanned helicopter equipped with contact electrostatic spraying system in paddy field.The results showed that the electrostatic spray was used to measure the amount of pesticide deposition in the upper,middle and lower layers of rice plants.The distribution uniformity of pesticides in rice plants is greatly improved.Under static spray conditions,increasing the height will reduce the amount of spray deposition,but will not affect the uniformity of spray deposition.