摇臂式喷头副喷嘴仰角及位置参数的优化

Optimization of impact sprinkler sub-nozzle parameters of elevation angle and position

摇臂式喷头副喷嘴的主要作用是增加喷头近处的喷水量，从而提高喷头的喷灌均匀度，因此对摇臂式喷头副喷嘴的研究具有重要意义。该文采用流场模拟和试验相结合的方法对摇臂式喷头的副喷嘴结构参数进行了优化设计。首先采用逆向工程的设计方法，运用Pro/E建立了摇臂式喷头的三维结构，选择副喷嘴的仰角和位置为待优化参数，设计出9种副喷嘴结构的摇臂式喷头。运用Pro/E和HyperMesh软件建立了9种副喷嘴结构摇臂式喷头的三维内流道模型，利用CFD软件FLUENT对9种喷头的内流道进行三维模拟，运用快速成型技术加工出喷头样品进行试验验证，在矩形组合方式下运用4种插值方法（距离插值法、线性插值法、立方插值法和三次样条插值法）计算喷灌组合均匀度，并且利用Sprinkler3D 软件通过二维插值的方法建立了9种喷头的压力水量分布模型，对喷头喷洒均匀性进行评价。结果表明，6号喷头（副喷嘴位置参数为19.8 mm、仰角参数为18°）的模拟流量和速率较大，试验水量分布在2～12 m之间能够保持较好均匀性，且射程达到14 m以上，喷灌均匀度在压力为250和300 kPa下都达到80%以上。因此，副喷嘴位置参数19.8 mm、仰角参数18°为摇臂式喷头副喷嘴的最佳结构参数。该研究为摇臂式喷头结构设计和喷灌系统优化等提供参考。

The chief function of sub-nozzle of impact sprinkler is to increase the near precipitation depth, thereby improving the uniformity of sprinkler irrigation. In this study, flow field simulation combined with experimental validation method was applied to optimize the key structural parameters （elevation angle and position） of impact sprinkler. Nine kinds of elevation angles and positions of sub-nozzle combinations were designed with the established three-dimensional structures of the impact sprinkler by Pro/E software. The three-dimensional inner flow channel model of impact sprinkler with nine kinds of sub-nozzle structure was established. The inner flow channel simulations of all kinds of impact sprinkler were performed by FLUENT of Computational Fluid Dynamics （CFD） software. Considering structural feature, the precision requirement, the procession quality, and the cost of product, the SLA RPT （Stereo lithography Apparatus Rapid Prototyping Technology） was selected to prototype the impact sprinkler with nine kinds of sub-nozzle. The nine kinds of models were processed into samples for experimental verification. Under the rectangular combinations, four interpolation methods （distance interpolation method, linear interpolation method, cubic interpolation method and cubic spline interpolation method） were used to calculate the Christiansen uniformity coefficient and nine kinds of water pressure distribution models were established by Sprinkler 3D software in two-dimensional interpolation method. The result showed that the impact sprinklers with sixth sub-nozzle （position parameter of 19.8 mm, the elevation angle parameter of 18°） performed more reliable. The study about sub-nozzle of impact sprinkler’s structural parameters improved the nozzle near water distribution effectively. Its flow rate of simulation was biggest. The yield of water distribution in 2-12 m could maintain good uniformity. And the sprinkler range of the sixth sub-nozzle was more than 14 m, better than before and increased by more than 2 m. The sprinkler irrigation uniformity was calculated with the four different interpolation methods and results were increased obviously. Under the pressure of 250 and 300 kPa （especially the pressure of 300 kPa）, the Christiansen uniformity coefficient both was more than 80%, which was an increase of 4% and 5% above than before. With the increase of the pressure, Christiansen uniformity coefficient was still consistent generally. The structural parameters of sub-nozzle （position parameter of 19.8 mm and the elevation angle parameter of 18°） of impact sprinklers were more reasonable. This study provides valuable information for structural design of sub-nozzle, impact sprinkler and sprinkler system optimization.