The flying prevention effect of plant protection UAV is composed of many factors, such as operation parameters and the performance of the plant protection machine itself; Uncontrollable factors, such as wind speed and direction.

Although the nozzle is only a small part of the spraying system, it is critical to the spraying quality.

1. UAV nozzle layout

Single rotor wing plant protection UAV: generally, single rod nozzles are uniformly distributed, which is characterized by a single wind field.

Multi rotor plant protection UAV: It has multiple wind fields with opposite directions. The previous distribution of nozzles will lead to confusion in the fog field, and even the liquid medicine will be sucked into the motor and propeller by the airflow. The nozzle placed under the motor and propeller is to effectively use the downforce wind field of the multi rotor plant protection UAV without causing fog field disorder.

2. Nozzle and Drift Evaporation

Liquid medicine drift is the process of pesticide droplets flying away from the flying target. The minimum droplet drift distance can be as long as several kilometers, which not only causes waste of pesticides, reduces the operation effect, but also may cause economic disputes and losses. The evaporation process of evaporative droplets from liquid to gas directly reduces the effective utilization rate of liquid medicine.

3. Main factors affecting the drift and evaporation of liquid medicine

01 Droplet size

The smaller the droplet diameter is, the more likely it is to drift, and the droplet with diameter less than 150 microns is the most likely to drift;

02 Wind speed

The greater the wind speed, the more likely to drift;

03 Distance

The farther the distance between the nozzle and the crop is, the more likely it is to drift and evaporate;

04 Temperature

The higher the temperature is, the easier the droplets will evaporate. Compared with the pressure nozzle, the drift of droplets produced by the centrifugal nozzle is greater. The smaller size of the droplets will directly lead to the aggravation of drift and evaporation problems. From the perspective of plant protection operation effect, it is more desirable that the droplets can be thinner, so that the area covered by the liquid medicine will be larger, so as to obtain a good effect of flying plant protection operation. Therefore, the design and operation parameters of plant protection UAV are often an effective balance between drift and spraying coverage area to achieve good spraying effect.

4. Requirements of droplet diameter for different types of operations

When coverage is very important, such as in some post seedling contact spraying applications, small droplets should be used to obtain good coverage; When spraying contact and inhalable herbicides, heavy fog droplets can be used to prevent the drift of fog droplets to the maximum extent. The UAV with pressure spraying system supports the replacement of the nozzle. The use of the nozzle can be adjusted according to the actual situation of the operation to achieve the best operation effect.