Performance of an Iris Mechanism Equipped with Fixed and Rotating Deflector Plates for Variable Rate Sprinkler Irrigation

摘要

Technologies have been developed for variable rate irrigation (VRI) systems to apply water based on the spatial and temporal variability of field conditions. To verify the suitability of the water distribution patterns of an iris-type mechanism applied in VRI systems, rotating and fixed spray plate sprinklers (RSPSs and FSPSs, respectively) each equipped with two different deflector plates were attached to the mechanism. Tests indoors were performed under the following conditions: iris mechanism orifices 4.93 and 6.94 mm in diameter, a sprinkler at a height of 0.91 m above the ground, and an operating pressure of 103 kPa. Mathematical overlaps were also performed for 1.5,- 2-, and 3-m sprinkler spacing. The results showed that: (1) individual FSPSs distributed water with higher intensity over a smaller distance from the sprinkler than RSPSs, which distributed water at a lower application rate but over a greater distance; (2) the simulated sprinkling uniformities of lateral line travel were 61.2%-91.6% and 88.5%-98.7% for FSPSs and RSPSs, respectively, under different sprinkler spacing conditions; (3) the uniformity of sprinkling decreased by as much as 30.5% for FSPSs and 7.4% for RSPSs with increased sprinkler spacing; (4) FSPSs presented high potential for surface runoff; and (5) the phenomenon of jet inversion did not affect the uniformity of the iris mechanism's water distribution, especially for RSPSs.