SPRINKLER PERFORMANCE AS AFFECTED BY NOZZLE INNER CONTRACTION ANGLE

The discharge-pressure relationship for the orifice nozzle is essentia l for developing new sprinkler prototypes and designing sprinkler irri gation systems. In this work, the sprinkler nozzle inner contraction a ngle was varied from 20 degrees to 90 degrees to establish the relatio nship between discharge and pressure. The sprinkler nozzle discharge i ncreases exponentially with increasing pressure. The discharge exponen t is essentially independent of the nozzle contraction angle and can b e taken as 0.5, while the discharge coefficient decreases significantl y with increasing contraction angle. Sprinkler rotation speeds measure d for different contraction angle nozzles decreased as the angle incre ased. Water distributions were tested indoors for various contraction angles. Sprinkler nozzles with contraction angles ranging from 20 degr ees to 60 degrees produced approximately equal pattern radii and simil ar water application profiles, but the pattern radius was significantl y reduced for contraction angles above 60 degrees. The optimum inner c ontraction angle is about 30 degrees.