ABSTRACT
The objective of this study was to quantify the influence of the spring tension, of the hammer of a rotary sprinkler (Naan model 233/92) on the volume of water and hydraulic energy absorbed from the deviated portion of the main jet. The importance of this study stands out in the elaboration of technical standards applied to irrigation equipments (ISO, ASAE, ABNT), seeking to supply inputs to mathematical models of ballistic trajectory, to simulate sprinkler performance under variable conditions of wind and soil surface topography. The action of the oscillating arm (hammer) constantly interferes in the main water jet during the whole time the irrigation system is operated in the field. Until the present moment, no standards exist in relation to the degree of tension of the spring coupled to the hammer, which leaves some uncertainties in the initial process of preparing the sprinklers for laboratory and field tests. The obtained results demonstrated that as a function of the hammer oscillation period (tension of the spring), the nozzle diameter and the operational pressure, a variation can be noticed between 4 and 40% of the deviated volume of water and a reduction of 35 to 55% of the available energy to the ballistic movement of the intercepted volume of water.
Key words:
sprinkler; technical standards; irrigation; laboratory test