Abstract
Background: Due to the influence of external wind speed and their flight speed, the droplets
sprayed by the plant protection Unmanned Aerial Vehicles (UAV) have serious drift and volatilization.
Objective: The aim was to study the atomization characteristics of the fan-shaped atomizing nozzle of
UAV under different inlet pressures and in different internal cavity diameters.
Methods: Firstly, the Realizable k-ε turbulence model, DPM discrete phase model, and TAB breakup
model are used to make a numerical simulation of the spray process of the nozzle. Then, the SIMPLE
algorithm is used to obtain the droplet size distribution diagram of the nozzle atomization field. At last,
the related test methods are used to study its atomization performance and the changes of atomization
angle and droplet velocity under different inlet pressures and in different internal cavity diameters; the
distribution of droplet size is also discussed.
Results: The research results show that when the diameter of the internal cavity is the same, as the inlet
pressure increases, the spray cone angle of the nozzle and the droplet velocity at the same distance from
the nozzle increase. As the distance from the nozzle increases, the droplet velocity decreases gradually,
the droplet size distribution moves to the direction of small diameter, and the droplets in the anti-drift
droplet size area increase. Under the same inlet pressure, as the diameter of the internal cavity increases,
the spray cone angle first increases and then decreases, and the droplet velocity at the same distance
from the nozzle increases. As the distance from the nozzle increases, the droplet velocity decreases
gradually, the droplet size distribution moves to the direction of large diameter, and the size of the large
droplets increases, thereby, not meeting the condition of anti-drift volatilization effect.
Conclusion: Under the parameters set in this study, i.e., when the inlet pressure was 0.6 MPa, and the
internal cavity diameter was 2 mm, the best atomization result was obtained.
Keywords:
Plant protection UAV, droplet drift, fan-shaped atomizing nozzle, numerical simulation, droplet size, atomization field.
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