Abstract
In pump-turbines, high pressure fluctuation is one of the crucial instabilities, which is harmful to the stable and effective operation of the entire unit. Extensive studies have been carried out to investigate pressure fluctuations (amplitude and frequency) at specific locations. However, limited research was conducted on the distribution of pressure fluctuations in turbine mode in a pump-turbine, as well as the influence of the number of runner blades on pressure fluctuations. Hence, in this study, three dimensional numerical simulations were performed to predict the distribution of pressure fluctuations with different numbers of runner blades in a prototype pump-turbine in turbine mode using the shear stress transport (SST) k-ω turbulence model. Three operating points with the same hydraulic head and different mass flow rates were simulated. The distribution of pressure fluctuation components of blade passing frequency and its harmonics in the direction along the whole flow path, as well as along the circumferential direction, was presented. The mass flow rate and number of runner blades have great influence on the distribution of pressure fluctuations, especially at blade passing frequency along circumferential direction. The mass flow rate mainly affects the position of peak pressure fluctuations, while the number of runner blades mainly changes the number of peak pressure fluctuations. Additionally, the number of runner blades influences the dominant frequencies of pressure fluctuations especially in the spiral casing and draft tube.
Highlights
Pumped storage power plants (PSPPs) have rapidly developed in recent years to balance the variation of loads, which is induced by the large investment of renewable energies in the power grid [1,2]
The conclusions that can be drawn from the numerical simulations are as follows
Conclusions that can drawnamplitude from the numerical simulations arewhich as follows
Summary
Pumped storage power plants (PSPPs) have rapidly developed in recent years to balance the variation of loads, which is induced by the large investment of renewable energies (such as solar energy and wind energy) in the power grid [1,2]. A reference survey shows that, a large number of experimental and numerical studies have been carried out on the generation mechanism and characteristics of pressure fluctuations in pump-turbines. For examples: Liu et al [11] has studied the pressure fluctuations in the transient process of a pump-turbine in turbine mode, with discussions of the influence of misaligned guide vanes (MGV). In the present study, 3D numerical simulations were performed using the SST k-ω turbulence model to investigate the distribution of pressure fluctuations in a prototype pump-turbine in turbine mode with different numbers of runner blades. Several operating points in turbine mode were studied to find out the influence of the number of runner blades on pressure fluctuations
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