Characterising droplets and precipitation profiles of a fixed spray-plate sprinkler

Droplet characteristics and precipitation profiles of a fixed spray plate sprinkler (FSPS) were characterised in some indoor experiments were conducted using various deflection plates (36-grooved blue, 30-grooved green and 36-grooved black plates). Four nozzle diameters (2.78, 3.97, 4.76 and 7.14 mm) were mounted on the sprinkler and operated at three pressures (69, 138 and 241 kPa) and at a nozzle height of 1.5 m. Drop characteristics were determined using a low speed digital photography method. The results showed that by increasing the nozzle size at a fixed operating pressure the resulted wetted diameter, peak application rate, droplet sizes and velocities were increased. With smaller nozzle diameters (2.78 and 3.97 mm) drop diameter increased as working pressure increased, while with larger diameters (4.76 and 7.14 mm) a reverse trend between drop size and working pressure was observed. Empirical equations were developed to estimate the wetted diameter and also volumetric mean diameter (VMD) and volume median diameters (D50) of droplets at different distances from the sprinkler as functions of sprinkler configurations.