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United States Department of Agriculture

Agricultural Research Service


Location: Application Technology Research Unit

Title: Air velocity distributions from a variable-rate air-assisted sprayer for tree applications

item Zhu, Heping
item Gu, Jiabing -
item Chen, Yu -
item Liu, Hui -
item Dong, Xiang -
item Ding, Weimin -
item Ozkan, Erdal -
item Krause, Charles

Submitted to: Symposium Proceedings
Publication Type: Proceedings
Publication Acceptance Date: May 1, 2012
Publication Date: July 12, 2012
Citation: Zhu, H., Gu, J., Chen, Y., Liu, H., Dong, X., Ding, W., Ozkan, E., Krause, C.R. 2012. Air velocity distributions from a variable-rate air-assisted sprayer for tree applications. CIGR-AgEng 2012: International Conference of Agricultural Engineering, July 8-12, 2012, Valencia, Spain. Paper No. C1547.

Technical Abstract: A capability that implements tree structure to control liquid and air flow rates is the preferential design in the development of variable-rate orchard and nursery sprayers. Air jet velocity distributions from an air assisted, five-port sprayer which was under the development to achieve variable-rate functions were measured at various heights inside and outside tree canopies and various distances from nozzle outlets. The air jet velocity was controlled by changing the sprayer fan inlet diameter. Air jet initial region length, transition length and expansion angle from five-port nozzles were calculated with an air jet model. The interaction point between adjacent air jets from the five-port nozzles was also determined from the air jet expansion angle. Air velocities at the sprayer travel speed ranging from 0 to 8.4 km/h were measured with a constant temperature anemometer system coupled with hot-film sensors. Air jets expanded at 50° angle and interacted at 0.027 from the nozzle outlets. When the sprayer travel speed was 0 km/h, the axial air velocity increased as the fan inlet diameter increased while it decreased in the hyperbola function with the increase of distance from the nozzle outlets. When the sprayer was on the move, due to the air entrainment and air jet diversity, the peak air velocity decreased with the increase of distance from nozzle outlets while the air flow pressure increased as the distance increased. The peak air velocity also increased slightly as the fan inlet diameter increased but the increase scale was not as great as the increase scale of the fan inlet diameter. Variations in the peak air velocities and airflow pressures with the tree volume and foliage density were significant. There were little variations in the peak air velocity and the airflow pressure with the travel speed and measurement height, confirming the sprayer was able to achieve variable air flow rates for different canopy sizes and foliage densities by controlling the fan inlet diameter.

Last Modified: 8/28/2016
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