水泵水轮机水轮机制动区的流动特性

为研究水泵水轮机水轮机制动区的不稳定流动特性，根据某抽水蓄能电站建立水力模型，应用计算流体动力学软件Fluent模拟其流动特征．采用SST k-ω模型和SIMPLEC算法计算水轮机制动工况的内流场和外特性，并结合试验数据进行对比验证．结果表明，水泵水轮机在水轮机制动工况随流量的变化水头变化不大，在力矩为0时的水头最低；导叶开度越大，进入制动区时所需的转速越高，且流量越大，可以通过调节导叶开度防止水泵水轮机进入制动区；导叶工作开度下力矩为0时的流场不存在涡结构，随着流量的减小，在叶片和活动导叶的进口以及固定导叶和活动导叶之间出现大量的回流涡，并且呈现出类周期性分布特征；转轮中的回流涡是由于前倾式叶片的倾角较大产生的，导叶中的回流涡是由于流体流动方向与导叶叶片的冲角引起的．以上结论可为水泵水轮机的优化设计提供一定的理论基础．

Flow characteristics of pump-turbine at turbine braking mode

To study the instability characteristics of pump-turbine at turbine braking mode, a hydraulic model was established based on a pumped storage power station. The SST k -ω model and SIMPLEC algorithms were used to simulate the internal flow fields and external characteristics at tinblue braking condition. Compared with the experimental data, the simulation results were examined. The results show that the head changes is small as flow rate changes in turbine braking condition. Higher rotating speed is needed to get into the braking mode as the opening of guide vanes increase. The pump turbine can be prevented from running into braking mode by adjusting the opening of guide vanes. Flow is regular and there is no vortex structure at zero moment point when guide vanes at operating opening. There have lots of periodical distribution vortexes in inlet of blades and guide vanes as well as the region between guide vanes and stay vanes with flow rate decreased. The vortexes in runner are caused by large forward inclination of blade, while vortexes in guide vanes are due to the angle of attack between flow direction and guide vanes. These conclusions can provide a theory basis for optimal design for pump-turbine.