Influence of rear nozzle on sprinkler irrigation uniformity

Abstract

The article presents results of researches on the influence of the rear nozzle on the sprinkler irrigation uniformity.The experimental researches were carried out in November/December 2016 at the field overgrownwith Rhodes grass (Chloris gayana), located in north-east Tanzania. Irrigation system installed on the field was based on movable Naan 5035 overhead sprinklers (plastic, impact) with six different main nozzles of sizes (3.5, 4.0, 4.5, 5.0, 5.5, 6.0 mm) and a rear nozzle (2.5 mm). Sprinklerswere installed on lightweight stands of the height 1.70 m and spaced 15 meters. The uniformity testing consisted of a rectangular grid of collectors placed on the ground. During the experiments a total of 12 catch can tests were conducted for variants with and without the rear nozzle. The coefficient of uniformity (CU) was evaluated using the Christiansen formula. During the experiments the highest CU values were obtained for most variants with installed both nozzles (main and rear). Maximum value of the Christiansen coefficient of uniformity (89.07 %) was observed for 4.0 mm main nozzle and rear nozzle. Maximum difference of the CU coefficients (11.8 %) for the variants with and without the rear nozzle was noted for the main nozzle diameter 5.0 mm