摘要
为分散喷头主射流,提高喷头的喷洒均匀度,使喷头适用于农业低压喷灌,该研究结合射流与撞击流提出了一种射流撞击式旋转喷头。首先对比了射流撞击喷头与射流不撞击喷头的水力性能,通过正交试验分析了各结构参数值对射程和组合均匀系数的影响,得到副喷嘴结构优化参数,最后将优化后的射流撞击喷头与改进前的传统15PY2喷头进行水力性能及水滴粒径分布对比。研究结果表明,射流撞击使射程末端水量高点降低,同时射程得到提升,射程平均提升4.39%,在相同压力及组合间距下覆盖范围更大。影响喷头工作性能的结构参数依次为副喷管长度、副喷嘴进口锥角、副喷管内径、副喷嘴仰角,而副喷嘴仰角对射程与组合均匀系数影响最大,15型射流撞击喷头最佳结构参数组合为:副喷管长度20 mm、副喷嘴进口锥角55°、副喷管内径6 mm、副喷嘴仰角33°。射流撞击喷头在压力150~300 kPa下组合均匀系数和综合评分均高过传统15PY2喷头,组合均匀系数平均提升4.84%,综合性能平均提升4%,证明了射流撞击应用于旋转式喷头具有优势。在射程前中段,150和250 kPa下射流撞击喷头水滴直径更大;在射程后段,150 kPa下射流撞击喷头水滴直径更大,但在250 kPa下水滴直径更小。研究所得到的喷头结构及结论可为后续研究射流撞击对水力性能的影响提供参考。
An asymmetric impinging jet collision mode is adopted to design the jet impingement sprinkler.By using the secondary jet to collide with the main jet,the movement and fragmentation mode of the main jet are changed to optimize the dispersion effect of the jet.The main body structure of the sprinkler is similar to that of a traditional impact sprinkler to meet the wetted radius requirements.The focus of the study is on the structure of the secondary nozzle,including the inner diameter of the secondary spray tube,the elevation angle of the secondary nozzle,the length of the secondary spray tube,and the inlet cone angle of the secondary nozzle.The sprinkler is made of aluminum alloy material and designed with a segmented structure plug-in design to avoid changes in the jet direction caused by threaded connections.The wetted radius and Christiansen's uniformity coefficient are selected as evaluation indicators.The wetted radius is calculated using interpolation algorithms,and the Christiansen's uniformity coefficient is calculated by using MATLAB program and a interpolation mathematical model to calculate the radial water application rate distribution for the square layout scheme.The experiment is conducted in a windless experimental hall,and the influence of various geometric parameters of the secondary nozzle on the water application rate distribution is evaluated through comprehensive evaluation of the wetted radius and Christiansen's uniformity coefficient using the CRITIC weighting method.According to the experiment,the coefficient of variation of flow rate for the nine different combinations of structures under different pressures is less than 2%.It can be concluded that the four structural parameters changed in this study do not affect the flow rate.By analyzing the average flow rate of the nine combinations,it is found that the flow rate is proportional to the pressure,and the flow rate at each test pressure is greater than 0.08 m^(3)/h,which means that the wetted radius of the sprinkler is the farthest distance from the centerline of the sprinkler to the point where the water application rate is 0.26 mm/h.By comprehensive scoring,the optimal structural combination for the full pressure range of 150~300 kPa is secondary spray tube length of 20 mm,secondary nozzle inlet cone angle of 55°,inner diameter of secondary spray tube of 6 mm,and secondary nozzle elevation angle of 33°.A comparison experiment of the water hydraulic performance between the jet impinging sprinkler and the non-impinging sprinkler shows that the jet impinging sprinkler has a longer wetted radius and a slightly different water application rate distribution.Hydraulic performance tests were conducted on the optimal structure and the traditional 15PY2 sprinkler.It was observed that,under low pressure,the wetted radius of the jet impinging sprinkler decreased,while the Christiansen’s uniformity coefficient increased.Under medium pressure,the wetted radius increased,and uniformity improved.Moreover,the comprehensive performance of the jet impinging sprinkler was found to be superior to that of the traditional 15PY2 sprinkler under a full pressure range of 150 to 300 kPa.Finally,a comparison was conducted to analyze the droplet size distributions of the traditional 15PY2 sprinkler and the jet impingement sprinkler in the anterior middle and posterior sections.The results show that the jet impingement sprinkler produces larger droplet diameters at 150 and 250 kPa in the anterior middle section of the wetted radius.However,in the posterior section,it only exhibits larger droplet diameters at 150 kPa.At 250 kPa,the droplet diameters are smaller.The obtained structure and conclusions of the study provide a reference for future research on the hydraulic performance affected by jet impingement.
作者
王子鑫
蒋跃
潘绪伟
王莉莎
WANG Zixin;JIANG Yue;PAN Xuwei;WANG Lisha(Fluid Machinery Engineering Technology Research Center,Jiangsu University,Zhenjiang 212013,China)
出处
《农业工程学报》
EI
CAS
CSCD
北大核心
2024年第6期220-227,共8页
Transactions of the Chinese Society of Agricultural Engineering
基金
常州市重点研发计划(CE20222024)
镇江市重点研发计划(CN2022003)
江苏省研究生科研实践创新计划(SJCX22_1870)。
关键词
灌溉
喷嘴
水力性能
射流撞击
正交试验
irrigation
nozzle
hydraulic performance
jet impingement
orthogonal test