Determinação do perfil radial de aspersores a partir de ensaios de distribuição de água em sistemas autopropelidos de irrigação

Abstract

This paper presents a computational algorithm, in Visual Basic 6, to determine rain gun radial water distribution patterns, based on catch can data collected at standard tests of traveller irrigation machines. The algorithm was evaluated by using both simulated and measured data input. The simulated data input were obtained by running a software, named SIMULASOFT, in order to generate catch can data of a traveller irrigation machine transect section. Simulated values were computed considering the PLONA-RL250 sprinkler (nozzle = 20 x 6 mm; pressure = 490 kPa) working with four wetted sector angles (180º, 270º, 330º and 360º) and a 50 m h-1 linear traveling speed. The measured catch can data were obtained at field tests, held under wind speeds lower than 1.5 m s-1, of a traveler irrigation machine working with the PLONA-RL250, at 392 kPa, under the following conditions: i) nozzle = 14 mm; sector angle 240º, and traveling speed = 30 m h-1; ii) nozzle = 14 x 6 mm, sector angle = 270º, and traveling speed = 55 m h-1. Comparisons among radial water application profiles measured at the test bench and the ones generated by the algorithm indicated that computed profiles based on simulated data were more accurate than the computed profiles based on field measured data. A great similarity obtained with simulated input data demonstrate the numerical accuracy of the proposed algorithm. The reasonably good resemblance of radial patterns generated by the algorithm, when using experimental input values, demonstrates that catch can transect values collected during standard field test of traveller irrigation machines may be used in order to determine rain gun radial water distribution pattern.