THE INFLUENCE OF LATERAL WIND VELOCITY ON THE DOWNWASH FLOW AIR VELOCITY GENERATED BY ROTORS OF SPRAYING DRONE

Abstract

In the case of unmanned aerial vehicle (UAV) spraying, wind speed, wind direction and flight speed and altitude are the main factors influencing the spray drift. The aim of this study is to determine the effect of lateral wind speed on the downward airflow velocity generated by drone wings. A four-propeller spraying drone was investigated. The research was carried out in 2022 at Vytautas Magnus University. A two axial fans stand was used to create lateral airflow. The speed of the motor shafts and impellers, and thus the air flow rate, are varied by two frequency converters. Thermo-anemometric sensors were used to measure the air velocity and were mounted at a height of 20 cm from the ground. The flight altitudes of the drone were two, three and four metres from the ground and the lateral air velocities were 2 m s^-1 and 10 m s^-1. Each test was repeated 3 times. The studies showed that the downward airspeed of a four-propeller drone (at 0.2 m from the ground) is dependent on the flight height and the lateral airspeed. The higher the flight altitude of the drone, the greater the influence of the lateral airflow velocity on the downwash velocity. Lateral airflow velocities of up to 10 m s^-1 did not affect the downward airspeed when the drone were flying at 2 m s^-1 at a height of 2 m. Increasing the flying height of the drone to 4 m and the lateral airspeed to 10 m s^-1 significantly reduced the downwash velocity. Therefore, a reduction in the drone's operating altitude is advisable as the lateral flow rate reaches the 10 m s^-1 limit.