| Impact sprinkler is an important spray equipment in water-saving irrigation.The nozzle’s performance was effected by the structure, the degree of turbulence inside of the nozzle flow and the external jet fragmentation. In practical application, when the outside has some wind or slope, especially when the wind reached at level 3 or 4,the sprinkler range will be greatly reduced, drift loss has increased considerably, which seriously affected hydraulic performance of the sprinkler. Decreases of nozzle angle could achieve the goal of wind resistance and reduce drift loss. So it is significant to desigh a elevation adjustment mechanism which could adjust the angle of sprinkler.Research conclusions are as follows:(1) This study designed a elevation adjustable sprinkler. To adjust the elevation angle of sprinkler and reduce the effect of wind on water distribution, a set of adjustment device, which fixed on the original structure of the sprinkler, was developed. The adjustment device consisted of support bar, limited rod, flexible metallic hose, internal thread hollow shaft sleeve, set screw and adjusting screw. The elevation angle of sprinkler nozzle, 13°, 18°, 23° and 30°could be adjusted and fixed respectively. Verified the average sprinkler irrigation intensity under different conditions are less than allowed irrigation intensity(6 mm/h), it is consistent with sprinkler requirements. Each quadrant maximum deviation rate are less than 12%, conform to the requirements.(2) This issue studied numerical computational domain, boundary conditions and mesh and other related issues. Analyzing the changes of the secondary nozzle with nozzle elevation change has little effect on the overall water conservancy of nozzle performance. And the data analysis showed that when the secondary nozzle at different position, the maximum and the minimum error of the speed in the main nozzle exit were 3.5% and 0.6% respectively. At the same time simulation of the changes of the main nozzle exit short cylindrical length influence on the flow field of sprinkler, the main nozzle exit short cylindrical should be shortened, more conducive to internal flowof sprinkler. It paved the way for the optimal design of sprinkler.(3) This study made simulation on the jet fragmentation of sprinkler.Using fluid dynamics simulation software COMSOL software and multiphase flow model(Level set) studied the jet fragmentation situation when sprinkler changed the elevation and nozzle inlet pressure. And the jet fragmentation point were determined. This was experimentally validated, the relative error of simulation and experimental values of the maximum value of 8.1%, the minimum relative error of 1.97%, indicating the study was feasibility.In this study, the elevation adjustment device was designed and this could adjust the elevation of nozzle; And this tested its hydraulic performances,made a simulation of the flow field flow, determined the jet fragmentation points and so on; This achieved the research purpose, in accordance with the theme of precision irrigation. |
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