方形喷嘴的中低压喷洒水滴性能试验研究

Experimental Study on Performance of Square Nozzle in Sprinkler Irrigation Systems under Low-intermediate Operating Pressure

【目的】研究喷嘴出口形状和散水结构对喷洒水滴特性的影响。【方法】通过视频雨滴谱仪测量了方形喷嘴在有无摇臂结构下的喷洒水滴特性。以圆形喷嘴作为对照组,分析了中低压下喷嘴形状对喷洒水滴直径分布、喷灌强度和动能强度等水力性能的影响,对比了摇臂结构对改善方形喷嘴喷洒性能的效果。【结果】在中低压条件下,方形喷嘴和圆形喷嘴的喷洒效果相似。方形喷孔对喷洒水量分布的改善效果不显著,水量主要集中在73%射程处。在近喷头的喷灌范围内,方形喷孔产生的水滴直径和动能均比圆形喷孔产生的水滴大,将方形喷嘴结合摇臂等辅助散水结构可以加强水射流分散程度的同时降低射程末端水滴打击动能。【结论】因此,辅助散水结构可以改善方形喷孔产生的水滴直径大、动能强度大的缺点,既保留高散水性能又降低水滴对土壤和作物的伤害。该研究对于中低压喷灌系统的喷嘴结构设计具有参考价值。

【Objective】The performance of sprinkler irrigation systems depends on many design factors and in this paper,we study the effect of orifice shape and the impact-arm of the nozzle on spraying characteristics when the systems are operated under low-intermediate pressure.【Method】The parameters characterizing the water droplets were measured by the 2D-dideo-distrometer.Taking the circular nozzle as the control,the effects of orifice shape on water droplet diameters,water application rate and kinetic energy intensity were measured and analyzed.We also studied the effects of the impact-arm on spraying performance of the square nozzle.【Result】The spraying characteristics of the square nozzle and circular nozzle were similar when the sprinkler irrigation system was operated under low-intermediate pressure.The orifice shape did not improve water distribution significantly,and the precipitation was mainly concentrated at the 73% range.In the regions proximal to the nozzle,the diameter and kinetic energy of the water droplets of the square nozzle were larger than that of the circular nozzle.Combining the square orifice with auxiliary water dispersing structure such as the impact-arm can enhance dissipation of the water jet and reduce the droplet kinetic energy at the out edge of the wetting area.【Conclusion】A dispersion structure combined with the square nozzles can overcome the disadvantages of large diameter and kinetic energy of water droplets,reduce the damage of the water droplets to soil and crops,and retain good hydraulic performance of the sprinkler irrigation system.