Previous experimental and numerical analyses of the pressure pulse characteristics in a Francis turbine are extended here by using the unsteady Reynolds-averaged Navier-Stokes equations with the shear stress transport (Sst) turbulence model to model the unsteady flow within the entire flow passage of a large Francis pump turbine with misaligned guide vanes at the rated rotational speed. The S-curve characteristics are analyzed by a combined use of the model test and the steady state simulation with the aligned guide vane firstly. Four misaligned guide vanes with two different openings are chosen to analyze the influence of pressure pulses in the turbine. The characteristics of the dominant unsteady flow frequencies in different parts of the pump turbine for various misaligned guide vane openings are investigated in detail. The predicted hydraulic performance and the pressure fluctuations show that the misaligned guide vanes reduce the relative pressure fluctuation amplitudes in the stationary part of the flow passage, but not the runner blades. The misaligned guide vanes have changed the low frequencies in the entire flow passage with the change of the pulse amplitudes mainly due to changes in the rotor-stator interaction and the low frequency vortex rope flow behavior.

中文翻译：

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导向叶片未对准的混流式水泵水轮机中压力脉冲的数值预测

通过使用非稳态的雷诺平均Navier-Stokes方程和剪切应力传输（Sst）湍流模型，对混流式水轮机中压力脉动特性的先前实验和数值分析进行扩展，以对管道整个流动通道内的非恒定流进行建模。大型混流式水泵水轮机，其导向叶片在额定转速下未对准。首先结合模型测试和稳态仿真，利用对准的导向叶片对S曲线特性进行分析。选择四个带有两个不同开口的未对准的导向叶片，以分析涡轮中压力脉冲的影响。详细研究了各种未对准的导向叶片开口在泵涡轮机不同部分的主要非稳态流动频率的特征。预测的水力性能和压力波动表明，未对准的导向叶片会减小流道固定部分中的相对压力波动幅度，但不会减小流道叶片。未对准的导向叶片已经随着脉冲幅度的变化而改变了整个流动通道中的低频，这主要是由于转子-定子相互作用和低频涡流绳流动行为的变化。