JP50卷盘式喷灌机水涡轮水力性能的试验与模拟

Experiment and numerical estimation of performance of hydraulic turbine of JP50 reel sprinkle

针对目前国内卷盘式喷灌机用水涡轮的外特性和内部流场分布规律的研究较少,设计了水涡轮试验台,对JP50卷盘式喷灌机配套使用的水涡轮进行试验,得到了外特性曲线.采用全流场和结构化网格技术对水涡轮内部流动进行了数值计算,分析水涡轮在不同流量下的压力分布和速度矢量分布,得到了内部流动分布规律.结果表明:水涡轮的工作效率很低,最高效率仅为13%,最高效率点前效率曲线比较陡峭,最高效率点后效率曲线相对较为平坦;最高效率的数值计算与试验结果相对误差为6.87%;高压水通过水涡轮主要工作叶片后压力迅速递减,造成了较大的水力损失;进出口压差随流量的增大而逐渐增大,与水涡轮的水头-流量及轴功率-流量曲线相吻合;水涡轮叶轮出口处出现回流现象;水涡轮出口管道下壁面附近存在低压区,并且随着流量的增大低压区的面积逐渐减小,随之出现了涡流现象.

Because there is limited work on the hydraulic performance and internal flow in reel sprinkle hydraulic turbines in China presently, a hydraulic turbine test rig was designed and then the performance curve of the turbine of JP50 reel sprinkle was measured in this study. In addition, a series of numerical simulations of internal flow in the whole turbine were performed based on a structured mesh to analyze the fluid static pressure and velocity distributions at various of flow rates, and eventually the characteristics of internal flow were obtained. It was shown that the turbine efficiency was very low that the best efficiency was 13% only. The efficiency cmwe was steeper at low flow rates; at high flow rates, however, it became relative flat. The relative error at the best efficiency point between simulation and experiment was 6.87%. The stream pressure was decreased rapidly when the stream went through the primary working blades of turbine, resulting in a larger hydraulic loss. The pressure drop across the turhine was increased with increasing flow rate, such a tendency was consistent with the head- and shaft power-flow rate curves. There was a reverse flow at the outlet of the impeller. A low pressure zone existed near the lower wall of turbine discharge pipe; additionally, the size of the zonewas reduced with increasing flow rate and then a vortex flow effect occurred.