Numerical Simulation and Experimentation of Atomization Field of Fan-Shaped Atomization Nozzle for UAV

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.