低压条件下PY_115型摇臂式喷头水力性能试验

Hydraulic Performance of Impact Sprinkler Type PY_115 at Low Pressure

针对喷头在低压条件下工作时水力性能较差的问题,提出采用异形喷嘴降低水滴打击强度并改善喷洒均匀性的方法。选取PY115型摇臂式喷头为研究对象,设计了3套改进喷嘴的方案,在出口喷嘴上增加了1、2、3个凹槽,凹槽的尺寸均为宽0.5 mm,高0.3 mm,位置分别在出口喷嘴下方和左右两侧。在工作压力为200 kPa下进行了试验测量,同时在正方形组合间距为13～18 m时,采用Matlab语言编制程序对其进行了仿真计算。试验和计算结果表明:在低压条件工作时,随着凹槽数量的增多,流量增大,射程缩短8.1%～9.4%,末端水滴直径降低系数为2.9%～6.8%,平均喷灌强度增大并均符合规范要求。增加凹槽有利于提高组合均匀系数,出口喷嘴增加3个凹槽时效果最佳,组合均匀系数最高超过90%,证明了所设计异形喷嘴方案的可行性。

To overcome the poor hydraulic performance problem of impact sprinkler when operating at low pressure,a program of modifying the shape of outlet nozzle was put forward.It was used to reduce the droplet impact strength and improve the uniformity coefficient.Impact sprinkler typed PY115 was chosen and three improved nozzles were designed.One,two or three notches were to be added in the outlet nozzle,respectively.All the notches were 0.5 mm in width and 0.3 mm in height and they were set at bottom,left or right side of the outlet nozzle.Experiments were carried out under the low operating pressure of 200kPa.When the rectangular spaces were 13m to 18m,Matlab was used to establish a program to simulate the hydraulic performances.The results showed that with the increase in the number of notches,the flow-rate increased,the wetted radius were shortened by 8.1% to 9.4%,the reduced coefficient of droplet diameter was 2.9% to 6.8%,the average irrigated intensity increased and complied with national requirement.The combined uniformity coefficient was improved for all the improved nozzles.The effect was more obvious when three notches were added in the outlet nozzle and the maximal uniformity coefficient can be more than 90%.Modifying nozzle shape was proved to be an available program as a result.