To explore the hydraulic performance of the impact water turbine of JP75 hose reel irrigation machine,experimental investigations were conducted by replacing the load of the machine with the baking torque of an eddy-current brake.The internal flow characteristics of the turbine were also investigated numerically based on the SST k-ω turbulence model.On this basis,orthogonal numerical experiments were made to determine the main factors affecting the hydraulic performance of the turbine.The results showed that the power and head loss of the turbine were increased as a parabola with the increase of the flow rates,but the maximum efficiency of the turbine under different conditions was less than 35％.A recirculation zone was found downstream of the inlet nozzle exit,which reduced jet velocity of the nozzle,resulting in the reduction of torque produced by the turbine.The flows out of the nozzle passed the impeller mainly through a mainstream impeller passage,and the pressure on the pressure side of the blade in the mainstream passage was higher than pressure in other areas of the impeller.The flow velocity in the annular channel downstream the trailing edge of the blades was relatively high,which blocked the flow inside the impeller and resulted in the recirculation in the impeller passages.The diameter of nozzle orifice and the blade tip clearance had significant influence on the hydraulic performance of the water turbine.An improved water turbine,with a novel nozzle and appropriate blade cutting and axial impellercasing clearance was obtained based on the numerical orthogonal tests.The best efficiency of 52.21％ was achieved for the modified model optimized by numerical orthogonal experiments.Compared with the original model,the modified model showed a significant overall reduction in head loss (20％ ～30％),an improvement in output power (10％ ～ 15％) and an efficiency increment of 12 ～ 17 percentage points under different operating conditions.%为了揭示JP75卷盘式喷灌机切击式水涡轮的水力性能及内部流动特征,采用电涡流制动器阻力代替喷灌机负载,进行水涡轮水力性能试验,并基于SST k-ω模型对水涡轮内部流动进行数值模拟.在此基础上,通过模拟正交试验对影响水涡轮水力性能的主要因素进行分析.研究结果表明,水涡轮进出口水头差及输出功率随流量增加近似呈抛物线型增加,不同工况下水涡轮效率均低于35％;水涡轮喷嘴出口处存在回流区,回流区的低速流动降低了喷嘴射流速度,造成水涡轮驱动力矩下降;叶轮内存在一个主过流叶片通道,喷嘴出流在叶轮内主要由主过流通道流经叶轮,主过流通道内叶片工作面压力高于其他区域;叶片出口侧环形流道内流速相对较高,对叶轮内非主过流通道流动起阻滞作用,导致叶轮区形成回流漩涡;喷嘴出口直径和叶片侧端间隙大小对水涡轮水力性能有显著影响,模拟正交试验获得了喷嘴出口直径24 mm、叶片侧向切削点与叶轮旋转轴径向距离52.7 mm、叶片侧端间隙6.8mm的水涡轮改进方案;与原型水涡轮相比,不同工况下,改进方案水涡轮的进出口水头差降低了20％ ～ 30％,输出功率提高了10％ ～ 15％,效率提高了12 ～ 17个百分点,最高可达52.21％.
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