基于离心泵的多级液力透平的性能预测与数值模拟

建立多级离心泵的全流道三维实体模型,划分网格后导入Fluent定义边界条件.采用定水头变转速模拟方案,选取600m水头时不同转速工况点进行计算.绘制综合特性曲线并确定最高效率点对应的单位转速、单位流量.研究不同转速时透平的性能,得出透平的水头、功率曲线及最高点效率值随流量略微变化.固定转速改变流量做全流道数值计算,分析最优工况多级透平过流部件内部流场分布,发现进水室底部有两股液流混合撞击,反导叶有流动旋涡,出水室有螺旋尾迹涡带,叶轮头部还存在冲击损失等.针对以上现象,提出多级离心泵反转做透平使用时结构改进的措施.

Performance prediction and numerical simulation of hydraulic turbine based on multi-stage centrifugal pump

A substantial three-D model of full flow passage of multistage centrifugal pump was set up and after the meshing of the flow passage,the software Fluent was introduced to define the boundary condition.The scheme of constant head and variable speed was taken,to perform the hydraulic computation in the case of different rotation speeds and constant head of 600 m.The comprehensive characteristic curve was plotted and the specific speed and specific unit flow at the point of maximum efficiency were determined.The turbine performances at different rotation speeds were investigated and a conclusion was obtained that the turbine head,power and the highest efficiency varied a little with the flow rate.By means of changing the flow and keeping the speed constant,the full flow passage was evaluated numerically.Inner flow field distribution in the flow passage components of the multistage turbine at the highest efficiency point was analyzed.It was found that in the suction casing there was mixing impact of two streams at the bottom;in the diffuser,there was vortex band in the spiral wake.There was also an impact loss at the impeller front.Aimed at the foregoing phenomena,some improvement measures for the structure of the multi-stage centrifugal pump as a turbine were presented.