1. Research background

 Spraying pesticide in orchards is a most important part in the fruit planting , which is a labor-intensive, high-input and environmentally harsh work. The traditional manually operated or semi-mechanized way to spraying the pesticide is ineffective(0.16-0.32 acre/person·hour) and the efficiency of pesticides is about 30%. Spraying the pesticide by the air-assisted orchard sprayer is gradually instead of the traditional working state. The efficiency of pesticides by using the air-assisted orchard sprayer can be raised to 50% at least. The feature of the equipment is the droplets are blew by the air produced by the fan form the sprayer to the fruit canopy, the branches and leaves are swing so that the two sides of the leaves can be deposited the droplets even in the middle of the canopy. Air-assisted orchard sprayer is a kind of high efficiency technical equipment for spraying the pesticide in the developed country. The working performance can exceed 3.2 acre/ hour with the driving speed 1.0m/s-2.0m/s.

2.  Key techniques

(1)The air-assisted spraying technique used in the plant protection machinery has two aspects of advantages. On the one hand, droplets are blew by the fan form the sprayer to the fruit canopy so that the droplets can resist the wind interference, which can reduce the droplets drift. On the other hand, the branches and leaves are swing due to the strong wind from the fan so that the two sides of the leaves can be deposited the droplets even in the middle of the canopy, which can enhance the penetrability and distribution uniformity of the droplets.

(2) The droplets flow field can be changed to match the fruit canopy though adjusting the angle of the fan baffle and changing the nozzle type so that the spray distribution and the airflow distribution are very good fit to the fruit canopy in vertical. Moreover, the spray dosage and the air supply are variable based on the geometrical characteristic of the canopy for enhancing the efficiency of pesticides.

3.Properties of product

4. Highlights

① The three-dimensional spatial distributing characteristics of the flow field outside the air-assisted orchard sprayer was analyzed by CFD (computational fluid dynamics) models. It was the theoretical foundation for optimizing the structure of the fan baffle, the guiding of the auxiliary air and the setting of the technical parameters.

② This type of the air-assisted orchard sprayer was equipped with a powerful air-blast system which the air supply and air direction could be changed in order to make the wind distribution uniformly. And there was a low-energy and noise fan made by polyethylene having the features such as low weight and steady running. Also there were a high pressure washing system and a special-shaped tank developed to realize the pesticide solution mixed by the back-flow spray and the tank washed by the high pressure spray. There is no residual after spraying in the tank.

③ The processing technology, assembly technique and the materials of this type of the air-assisted orchard sprayer all reach the international standard. The overall performance can achieve the international level as the similar products.