Hydraulic Performance Assessment of Sprinkler Irrigation with Rotating Spray Plate Sprinklers in Indoor Experiments

A recently developed rotating spray plate sprinkler (RSPS) with a six-grooved plate (R 3000) is evaluated in this paper. A set of nozzles numbered $15/128\mathrm{in.}$ (2.98 mm), $17/128\mathrm{in.}$ (3.37 mm), and $19/128\mathrm{in.}$ (3.77 mm) was tested with a nozzle elevation of 1.2 m using working pressures of 100, 200, and 300 kPa. The individual water distribution patterns, including the discharge–pressure relationship, wetted radius, sprinkler rotation speed, and water application rate, were evaluated under indoor experimental conditions. The results show that the discharge coefficient was mainly dependent on the nozzle diameter, which had a good value of more than 0.9 for all conditions. The wetted radius increased with the nozzle size as well as the operating pressure, and an empirical equation for those relationships was developed in this study. The sprinkler rotation time decreased with increasing operating pressure because an increase of the operating pressure resulted in an impact force from the nozzle to the plate sufficiently large to overcome the plate’s resistance. The sprinkler head produced quite similar water application parabola-shaped profiles at different nozzle sizes, and equations of the water application rate with regard to the distance from the sprinklers are provided. The average coefficients of determination for $d=2.98$, 3.37, and 3.77 mm were 88.2, 81.3, and 90.1%, respectively.