Testing method and anti-drift capability analysis of downwash airflow distribution characteristics of multi-rotor UAV in hover

Abstract. The shape of downwash airflow of multi-rotor plant protection UAV affects the distribution of fog droplets in the target canopy. The downwash airflow is susceptible to external natural wind, which results in the drift of fog droplets. In order to explore the anti-drift ability of rotor airflow to external natural wind, this paper applies external natural wind to UAV airflow at different altitudes in hovering state by using wind curtain aircraft. At the same time, numerical simulation method is used to simulate and analyze the results. The simulation test results show that the airflow of the UAV is different for the natural wind (4 m·s^-1, 8 m·s^-1, 12 m·s^-1) in different height directions, and the altitude is different (0.6 m, 1.0 m, 1.4 m, 1.8 m). As the increase of the height, the drifting resistance of the drone downwash airflow gradually decreases, and the whole airflow field shift phenomenon is obvious; At the same time, the test results show that the wind curtain is at the height of the crop canopy of 1.0m. When the speed of the air outlet is 8 m·s^-1, the degree of drift of the airflow is consistent with the simulation results, and the accuracy of the simulation results is verified. The results of CFD simulation verify the anti-floating performance of the downwash airflow in hovering state. At the same time, this paper provides a reference for the anti-floating research of multi-rotor plant protection drone droplets.