Compensation of spray angle to droplet drift under crosswind

Abstract: This study aims to explore the effects of side spray in the plant protection spraying on the droplet drift under different wind speeds and nozzle tilt angles. A sprayed test was performed on the three wind speed levels (1, 2, and 3 m/s), and four nozzle tilt angles (0°, 15°, 30°, and 45°). The droplet distribution was also measured under different levels. The control group was also set as a wind speed of 0 m/s, and the nozzle tilt angle of 0°. The mass distribution center of droplet and the coefficient of variation were then determined in the vertical and horizontal directions. The results show that there was a relatively small influence of crosswind wind speed and nozzle tilt angle on the droplet mass distribution center in the range of ±3 cm in the vertical direction. Specifically, the increase of crosswind wind speed and nozzle tilt angle caused the new variation in the vertical direction. The maximum decrease of coefficient of variation in vertical direction at 1-3 m/s wind speed is 12.3, 6.0 and 16.0 percentage points respectively. By contrast, there was a greatly different influence of the wind speeds and nozzle tilt angles on the droplet drift in the horizontal direction. The influence of the fog droplets on the wind speed decreased, as the tilt angle of the nozzle increased toward the negative direction of the wind speed. The fog droplets drifted excessively, when the compensation amount of the nozzle tilt angle exceeded the drift amount of the fog droplets under the current wind speed. The tilt angle of the nozzle at high wind speeds was greatly contributed to a greater change in the droplet drift. The speed of crosswind wind and the tilt angle of the nozzle presented a greater impact on the coefficient of variation in the horizontal direction. Furthermore, the horizontal coefficient of variation increased, whereas, the change of wind speed caused the horizontal coefficient of variation to increase first and then decrease, as the tilt angle of the nozzle increased. Consequently, the best compensated nozzle tilt angles were 3°, 7° and 11° under the conditions of 1, 2, and 3 m/s. This finding can provide a strong reference for the improvement technology of droplet drift in plant protection spraying.