Abstract
ABSTRACT End gun sprinklers can increase the irrigated area by center pivot irrigation systems without a substantial investment. This study was carried out at the Universidade Federal de Lavras, MG state, Brazil, and aimed to describe and validate a water distribution model for center pivot end gun sprinklers. The gun sprinkler PLONA-RL250®, attached at the end point of a center pivot, was used to evaluate the model in field tests. The sprinkler working conditions considered were nozzle diameters of 14 x 6 mm, working pressure of 292 kPa, and four asymmetric wetted angle adjustments (95 + 20º; 90 + 90º; 60 + 60º; 45 + 45º). These tests were carried out for wind speed lower than 0.9 m s-1. The measured and simulated irrigation depths showed an average absolute difference of 0.65 mm and determination coefficients from 71.55 to 89.37%. Based on the confidence coefficient (c = 0.82) the model can be classified as very good (0.76 ≤ c ≤ 0.85). Sprinkler wetted angle adjustment of 110º (95 + 20º) resulted in uniform water distribution and, for effective radius of throw between 70 to 90% of the gun sprinkler´s radius of throw, this working condition resulted in Christiansen’s uniformity greater than 80%.
Highlights
Material and MethodsThe use of a gun sprinkler attached at the end point of a center pivot allows adding irrigation area without a substantial investment (Waller & Yitayew, 2016)
Sprinkler wetted angle adjustment of 110o (95 + 20o) resulted in uniform water distribution and, for effective radius of throw between 70 to 90% of the gun sprinklers radius of throw, this working condition resulted in Christiansen’s uniformity greater than 80%
This curve has a large similarity to the theoretical geometric shape of Christiansen's uniform water distribution curve (Profile F) (Christiansen, 1942)
Summary
The use of a gun sprinkler attached at the end point of a center pivot allows adding irrigation area without a substantial investment (Waller & Yitayew, 2016). In order to evaluate the simulation data from the proposed model, at the Instituto Federal de Educação, Ciência e Tecnologia do Triângulo Mineiro (IFTM), in the city of Uberaba, MG state, Brazil, the sprinkler PLONA-RL250® was attached at the end point of a center pivot. This part circle gun sprinkler has a trajectory angle of 24o, a flange coupling of 2 1⁄2”, two impact arms and a slow reverse system. In order to evaluate this recommendation, the CU values were determined for the gun sprinkler with effectively irrigated radiuses of throw (R) of 100, 90, 80 and 70% of the gun sprinklers radius of throw
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