Experimental Study On Automization And Deposition Characteristic Of Orchard Air-assisted Sprayer Nozzle

The performance of nozzle plays an important role in the efficiency of pest control,according to the lack of the research on corollary nozzle of the orchard air-assisted sprayer indomestic, a new hollow cone nozzle was designed and its spray characteristics were studied inthis paper.The relationship between the nozzle structure parameters, the spray pressure and spray flow,spray angle was analyzed, Expressions of spray flow and spray angle were derived. Six nozzleswith different structure parameter were designed according to the commonly used spray flow andangle.The droplet size distribution without air-assisted was measured and analyzed under differentnozzle structure parameters, spray pressure and measuring positions. The results showed that thenozzle diameter, spray pressure, vertical height had significant influence on droplet size withsignificance level0.05, and the nozzle diameter has the strongest effect, spray pressure has theweakest effect; The optimum factor level combination: spray pressure was1.2MPa, the nozzlediameter was0.7mm, vertical height was200mm; The multiple regression model between thedroplet size and the main factors was constructed.An air-assisted sprayer test-bed was developed to study atomizing performance of thenozzle. The results showed that the impact of wind speed and spray distance on droplet size wasmainly related to the initial droplet size. The nozzle diameter of0.7mm or1.0mm, spray pressurerange of0.8~1.2MPa is suggested to achieve the low volume spray.The CV of two nozzlescombined with20°is smallest with an average of14.9%at the spray distance2.5m.The atomization flow field of the single nozzle and combined nozzle were measured by PIVsystem. The results showed that both the droplets’ velocity and vorticity increased as the spraypressure increased, and decreased as the nozzle diameter and spray distance increased. Whenspray with air-assisted, the droplet trajectory basically along the air flow direction, and dropletvelocity along the spray distance decay slower than no air-assisted; the atomization effect ofspray cross-regional was relatively stable when two nozzles combined with10°or20°.The new designed hollow cone nozzle was applied in the droplets deposition experiment ofjujube tree and orange tree. The experiment results showed that the faster sprayer speed, the lessspray deposit. The maxminum spray deposit on jujube tree and orange tree was33.09%and61.61%respectively when travel speed was0.5m/s. With different sampling heights, the dropletdeposition on the lower area of jujube tree was more than the middle area. The droplet depositionon the middle area of orange tree was minimum, and droplet deposition on the upper area slightlymore than lower area.