The movement and deposition of the droplets sprayed by agricultural unmanned aerial vehicle(UAV)are influenced by the complex downwash flow field of the rotors.Instead of conducting field experiment,a high speed parti...The movement and deposition of the droplets sprayed by agricultural unmanned aerial vehicle(UAV)are influenced by the complex downwash flow field of the rotors.Instead of conducting field experiment,a high speed particle image velocimetry(PIV)method was used to measure the movement and deposition of the droplets at different rotating speeds of rotors(1000-3000 r/min)or at different transverse injecting points(20-50 cm away from its nearby rotors)in the downwash flow field of an agricultural UAV with eight rotors and conical nozzles.The maximum speed and size of the high speed zone of the droplets were found greatly influenced by the downwash velocity.The initial spray angle of the nozzle declined with the increase of downwash flow speed.It was found that the downwash velocity could not only change the deposition zone of the droplets,but also influence their distribution.The increase of the downwash velocity would increase the deposition uniformity of the droplets.The nozzle position in the downwash flow field could also influence the deposition of the droplets.When the transverse distance between the nozzle and its nearby rotors increased,the relative deposition near the downwash flow of the rotors increased simultaneously.However,the distance between the deposition peak and the nozzle stayed constant.The initial spray angle of the nozzle was not influenced by the transverse distance between the nozzle and its nearby rotors.The research results could provide a theoretical basis and reference for the optimization of the spray application of multi-rotor UAV to minimize droplets deposition uncertainty.展开更多
In recent years,multi-rotor unmanned aerial vehicle(UAV)crop protection operations have experienced tremendous growth.Compared with manual operations,they have advantages such as high operational efficiency,small pest...In recent years,multi-rotor unmanned aerial vehicle(UAV)crop protection operations have experienced tremendous growth.Compared with manual operations,they have advantages such as high operational efficiency,small pesticide dosage,and low pesticide hazards for humans.However,the tiny droplets produced during UAV spraying for crop protection are affected by the rotor air flow and will drift in all directions in an uncontrollable manner,severely affecting the pesticide deposition pattern and resulting in pesticide waste.To improve pesticide use efficiency during multi-rotor UAV spraying,an electrostatic spray system was designed based on electrostatic spray technology and a six-rotor UAV.The proper operation parameters for the UAV electrostatic spray were determined by test,which were spray altitude of 50 cm above the crop,spray pressure of 0.3 MPa and charging voltage of 9 kV.Field test was performed based on these parameters.The results showed that compared with non-electrostatic spray,the electrostatic spray improved by 13.6%in the average deposition density above the sampling device and 32.6%in the middle.The research can provide a reference for designing multi-rotor UAV electrostatic spray devices.展开更多
Overall, this paper explains the related information about VTOL and trend of this technology worldwide. Also, it comes up with the distinction among VTOL and helicopter and fixed wing aircraft. This paper concentrates...Overall, this paper explains the related information about VTOL and trend of this technology worldwide. Also, it comes up with the distinction among VTOL and helicopter and fixed wing aircraft. This paper concentrates on domestic and international drones that utilize VTOL technology. Also, this paper gives the explanation about VTOL’s performance and object. Furthermore, this paper predicts the future of VTOL and which area this technology going to be used.展开更多
基金the National Natural Science Foundation of China(31601228)the Youth Science Fund of the Beijing Natural Science Foundation(6164032)the Youth Science Fund of Beijing Academy of Agriculture and Forestry Sciences(QNJJ201631)。
文摘The movement and deposition of the droplets sprayed by agricultural unmanned aerial vehicle(UAV)are influenced by the complex downwash flow field of the rotors.Instead of conducting field experiment,a high speed particle image velocimetry(PIV)method was used to measure the movement and deposition of the droplets at different rotating speeds of rotors(1000-3000 r/min)or at different transverse injecting points(20-50 cm away from its nearby rotors)in the downwash flow field of an agricultural UAV with eight rotors and conical nozzles.The maximum speed and size of the high speed zone of the droplets were found greatly influenced by the downwash velocity.The initial spray angle of the nozzle declined with the increase of downwash flow speed.It was found that the downwash velocity could not only change the deposition zone of the droplets,but also influence their distribution.The increase of the downwash velocity would increase the deposition uniformity of the droplets.The nozzle position in the downwash flow field could also influence the deposition of the droplets.When the transverse distance between the nozzle and its nearby rotors increased,the relative deposition near the downwash flow of the rotors increased simultaneously.However,the distance between the deposition peak and the nozzle stayed constant.The initial spray angle of the nozzle was not influenced by the transverse distance between the nozzle and its nearby rotors.The research results could provide a theoretical basis and reference for the optimization of the spray application of multi-rotor UAV to minimize droplets deposition uncertainty.
基金The authors acknowledge that the research was financially supported by National Key Technology Research and Development Program of the Ministry of Science and Technology of China(2014BAD06B01)Laboratory of Agricultural Mechanization Engineering Project(Provincial Key Laboratory).
文摘In recent years,multi-rotor unmanned aerial vehicle(UAV)crop protection operations have experienced tremendous growth.Compared with manual operations,they have advantages such as high operational efficiency,small pesticide dosage,and low pesticide hazards for humans.However,the tiny droplets produced during UAV spraying for crop protection are affected by the rotor air flow and will drift in all directions in an uncontrollable manner,severely affecting the pesticide deposition pattern and resulting in pesticide waste.To improve pesticide use efficiency during multi-rotor UAV spraying,an electrostatic spray system was designed based on electrostatic spray technology and a six-rotor UAV.The proper operation parameters for the UAV electrostatic spray were determined by test,which were spray altitude of 50 cm above the crop,spray pressure of 0.3 MPa and charging voltage of 9 kV.Field test was performed based on these parameters.The results showed that compared with non-electrostatic spray,the electrostatic spray improved by 13.6%in the average deposition density above the sampling device and 32.6%in the middle.The research can provide a reference for designing multi-rotor UAV electrostatic spray devices.
文摘Overall, this paper explains the related information about VTOL and trend of this technology worldwide. Also, it comes up with the distinction among VTOL and helicopter and fixed wing aircraft. This paper concentrates on domestic and international drones that utilize VTOL technology. Also, this paper gives the explanation about VTOL’s performance and object. Furthermore, this paper predicts the future of VTOL and which area this technology going to be used.
