水泵水轮机水轮机工况大流量区数值分析

为了研究水泵水轮机水轮机工况大流量区域的流场特性,依据某抽水蓄能电站水泵水轮机模型机进行建模,分别采用结构化和非结构化2套网格,基于剪切应力传输模型SST k-w和SIMPLEC算法对该区域流场进行了模拟,并与试验结果进行了比较验证,详细分析了大流量下转轮内部流动特性.结果表明：水泵水轮机进入大流量区后,由于流体相对转轮速度的不断提升,转轮流道内生成了周期性分布的涡结构并且涡结构不断增大,向流道出口边延伸,引起能量损失,导致转轮叶片压力面上流体速度的上升,进而对数值计算的网格质量提出了较高的要求,揭示了大流量区计算难度高的内在原因.结论可为水轮机工况大流量区域的数值计算和流场分析提供了理论依据.

Numerical analysis on flow in pump-turbine in turbine mode at high flow rates

To investigate the characteristics of flow in a pump-turbine in turbine mode at high flow rates,a geometrical model was established based on the prototype model of the pump-turbines for a pumped storage power station.The shear stress transport（SST） k-w turbulence model and the pressure-velocity coupling scheme SIPLEC were used to simulate the internal flow fields in the model by means of two kinds of mesh,i.e.structured and unstructured,and the obtained results were compared with the measured data.It was shown that there were periodically distributed vortexes in flow passages of the runner at a high flow rate.The scale of the vortexes steadily became larger and extended to the blade trailing edges with increasing of flow rate,causing energy losses.Moreover,such vortexes occupied some cross-sectional area of the passages,then the fluid velocity near the pressure sides of blade ascended.This vortex dominated flow has a high demand on quality of mesh in simulation,and it is the reason why the flow in high flow rates is difficult to be simulated.These conclusions can provide a theoretical basis for analysis and simulation of flow at a high flow rate.