JP75型卷盘式喷灌机水涡轮能量转换数值模拟分析

为了对JP75型卷盘式喷灌机水涡轮进行能量转换分析、参数优化及探究其内部流动性能,采用CFD技术,对转速为250 r/min下的水涡轮进行三维建模、多面体网格划分以及数值模拟.分析水涡轮压力云图和速度云图,发现进口管道中不合理的弯道、喉部、喷嘴设计导致了水涡轮运行效率偏低,来流中的压力势能未能转化为有效的叶片冲击动能,大量能量仍以势能的形式储存在液流中.分析过流断面流线图,发现叶片间隙及出口管道入水口处有大量涡旋产生,造成部分能量损失,从而表明现有的JP75型水涡轮进出口设计和叶片设计需要改进.对进水管道喉部之后的射流段和转轮这两处进行能量转换计算,平均效率分别为26.31%和45.44%,转换效率明显偏低.对现有JP75型卷盘式喷灌机水涡轮进行了参数优化设计,经计算,初步确定了优化模型的标称直径为0.201 m、射流直径为0.021 m、设计水头为13.65 m.

Numerical simulation analysis of energy conversion in hydraulic turbine of hose reel irrigator JP75

In order to carry out energy conversion analysis and parameter optimization for the hydraulic turbine in hose reel irrigator JP75, its internal flow at a rotational speed of 250 r/min was numerically simulated by using CFD technique. According to the pressure and the velocity contours predicted, the unreasonably designed bend and throat are responsible for low turbine efficiency. Through an analysis of the internal flow field, it is found that the turbine blades in the inlet and outlet are improperly designed, resulting in a large number of vortices in the blade clearance to generate a partial energy loss. The energy conversion in the jet section and runner was calculated, the average conversion efficiencies are 26.31% and 45.44%, respectively. Obviously, these conversion efficiencies are fairly low. On the basis above, the design parameters of the hydraulic turbine were optimized. The optimized nominal diameter, jet diameter and water head are 0.201 m, 0.021 m and 13.65 m, respectively.