Hydraulic performance tests and optimized working parameters of Teejet atomizing nozzles

Abstract: Teejet atomizing nozzle is one of the most important components in the mobile micro-sprinkler system for the greenhouse. Three kinds of fan-shaped nozzle structures with different diameters can fully meet the irrigation requirements to adjust the farmland microclimate for better crop growth stress in the various scenes. Therefore, this sprinkler can be expected for greenhouse irrigation, due to its wide application range, high safety, and long service life. However, there is no accurate reference to the parameters of sprinklers, such as hydraulic performance and operating conditions. The purpose of this study is to obtain a better configuration condition of atomizing nozzle. The hydraulic performances of the single and combined nozzle were optimized on the installation height, equivalent diameter, working pressure, and combined spacing of the Teejet atomizing nozzle. A water distribution test was carried out to verify the hydraulic performance parameters of atomizing nozzle under different working conditions. The experimental analysis, theoretical calculation, and comprehensive evaluation were then combined to clarify the influence of the equivalent diameter, installation height, and working pressure on the hydraulic performance of atomizing nozzle. The quantitative relationship was obtained between the installation height, working pressure, equivalent diameter, combination spacing and uniformity coefficient. A comprehensive evaluation index system was constructed using technical and economic indicators. Finally, the principal component analysis was implemented to determine the optimal configuration scheme for atomizing nozzles. The results show that: 1) The velocity of water flow increased significantly in the pipeline with the increase of working pressure, while the peak value of sprinkler irrigation intensity gradually increased to widen the spraying range. The slow water diffusion of a single nozzle was observed for the uniform water distribution, as the installation height increased. As such, the wider spraying range of the nozzle was obtained than before. In the same installation height and working pressure, the larger the equivalent diameter of the nozzle was, the larger the outlet flow was, and the greater the peak sprinkler irrigation intensity of the nozzle was. 2) There was the basically same variation trend of the combination uniformity coefficient in the three equivalent diameter sprinklers. The combination spacing presented the most outstanding influence on the combination uniformity coefficient. Furthermore, the combination uniformity coefficient tended to decrease first, then increase and finally decrease, with the increase of the combination spacing in the sprinklers. A relatively significant influence was also observed in the working pressure and installation height on the combination uniformity coefficient. 3) A comprehensive index evaluation model was established using principal component analysis. The optimal configuration conditions of atomizing nozzles were obtained by SPSS analysis, including, the nozzle equivalent diameter of 1.81 mm, the installation height of 0.6 m, combined spacing of 0.2 m, and working pressure of 400 kPa. This finding can provide theoretical support to the parameter configuration of mobile micro-sprinkler for greenhouse irrigation.