Study on pressure fluctuation and rotating stall characteristics in the vaneless space of a pump-turbine in pump mode

Journal of Energy Storage, Год журнала: 2024, Номер 94, С. 112385 - 112385

Опубликована: Июнь 13, 2024

Язык: Английский

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Rotor–stator interaction investigations in variable speed reversible pump-turbine at higher head

Physics of Fluids, Год журнала: 2024, Номер 36(3)

Опубликована: Март 1, 2024

Efficiency and grid stability can be improved by variable speed operation using doubly fed induction machine technology for pumped storage plants experiencing significant head variations. With the higher penetration of intermittent renewable energy sources, viz., solar wind, may stabilized operating reversible pump-turbines (RPTs) in off-design conditions. In a turbine mode, RPT is more susceptible to fatigue vibrations when at as result hydraulic instability generated rotor–stator interaction (RSI); therefore, its performance becomes even critical. The powerhouse structural components, including floors columns, could experience intense because this instability. Therefore, it essential investigate RSI RPTs head. These investigations present results numerical analysis associated pressure fluctuations high-head scaled model was used, simulations were executed utilizing shear stress transport k-ω turbulence model. performed best efficiency point conditions having optimized rotational speed. show that main source all RSI, where dominant frequencies are blade passing frequency (9fn) harmonics. It also found lowers RPT.

Язык: Английский

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Effects of vortex rope formation in draft tube of reversible pump-turbine – A review

Journal of Energy Storage, Год журнала: 2024, Номер 99, С. 113250 - 113250

Опубликована: Авг. 8, 2024

Язык: Английский

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Impact, analysis, and mitigation of flow instabilities in draft tube of Francis turbines

Physics of Fluids, Год журнала: 2025, Номер 37(2)

Опубликована: Фев. 1, 2025

Hydropower is a clean, renewable, and highly efficient energy source accounts for about 16% of global electricity production. Apart from baseload generation, hydraulic turbines are more often subjected to less off-design operating conditions handle the fluctuating demands stabilize power grid. These sub-optimal operations result in flow instabilities such as vortex breakdown inter-blade vortices, which reduce overall efficiency produce severe pressure pulsations. This review summarizes various forms theories developed explain phenomena. The impact these on turbine operation discussed. Mathematical models describe swirling flows downstream Francis runner also presented. Parameters that influence characteristics outlined. concludes with discussion methods alleviate adverse effects turbines.

Язык: Английский

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Rotor-stator interaction and vortex rope in the high-head variable speed reversible pump-turbine operating at minimum head

Physics of Fluids, Год журнала: 2025, Номер 37(3)

Опубликована: Март 1, 2025

The pumped storage hydropower (PSHP) has large head variations during its cyclic operation, and using variable speed units of reversible pump turbines (RPT) can extend operating range grid stability. In minimum conditions, the performance RPT in turbine mode is more important because it may experience fatigue vibrations due to hydraulic instabilities caused by rotor-stator interaction (RSI) vaneless space vortex rope draft tube. Therefore, investigate these phenomena RPTs at head. At flow rate, controller adjusts rotational value that yields highest efficiency, becomes “fixed” condition. present work investigates RSI associated pressure fluctuations (PFs) available conditions. analysis was performed best efficiency point (BEP) with three rates having fixed (corresponding efficiency). It observed fluctuates as a result presence low-pressure stagnation region inlet side runner blade. developed tube center high-velocity gradient. be concluded main source PF condition RSI.

Язык: Английский

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A Brief Review of Recent Research on Reversible Francis Pump Turbines in Pumped Storage Plants

Energies, Год журнала: 2025, Номер 18(2), С. 394 - 394

Опубликована: Янв. 17, 2025

As the core for energy conversion in pumped storage plants, pump turbine is also a key component process of building clean power grid, owing to its fast and accurate load regulation. This paper introduces current status research development turbines from perspectives significance, design optimization, operational performance, advanced methods, etc. Internal external characteristics such as transient flow evolution, structural vibration, flow-induced noise, etc., not only reflect performance (hydraulic, cavitation, sediment abrasion, stability etc.) but directly affect safe efficient operation system. It worth mentioning that space-time evolution internal an emerging direction, results which can be used predict conditions turbines. Moreover, application intelligent condition monitoring fault diagnosis aim prevent failures accidents plants.

Язык: Английский

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Investigation on the characteristics and formation mechanism of backflow in S-shaped region of a reversible pump-turbine

Physics of Fluids, Год журнала: 2025, Номер 37(2)

Опубликована: Фев. 1, 2025

When reversible pump turbines go through the S-shape region, there is some significant backflow regions in vaneless space, accompanied by severe pressure fluctuation. However, internal correlation and mutual influence mechanism among fluctuation, turbulent vortex structure, are still unclear enough current research. In this work, characteristics formation of turbine region figured out using computational fluid dynamics methods. The results indicate that Leading-Edge-Passage-Vortex caused adverse gradient dominant initial stage backflow. stage, interaction between inflow main reason causing high amplitude wideband fluctuation components space. development, centrifugal force play roles different regions, respectively. rotating stall phenomenon appears runner a low-frequency component 0.6fn 0.3fn∼0.45fn appeared, respectively, space runner. fully developed dominated concentrated flow area inlet, while pushed to upper crown lower ring. These findings can provide theoretical supports for improving stability operating off-design condition.

Язык: Английский

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Investigation on the unstable flow characteristic and its alleviation methods by modifying the impeller blade tailing edge in a centrifugal pump

Journal of Energy Storage, Год журнала: 2024, Номер 86, С. 111358 - 111358

Опубликована: Март 26, 2024

Язык: Английский

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Research on pressure pulsation characteristics of a pump-turbine in pump mode with rotating stall: Focus on the broadband frequency

Physics of Fluids, Год журнала: 2024, Номер 36(4)

Опубликована: Апрель 1, 2024

To investigate the adverse effects of rotating stalls on pressure pulsation characteristics a pump-turbine in pump mode, an unsteady numerical simulation was carried out by applying partially averaged Navier–Stokes turbulence model. The methods were carefully verified, and onset flow rate hump at performance curve heads good agreement with experimental data. stall appeared guide vane when ranged from 0.514 to 0.887 times best efficiency point (QBEP), frequency 11.7% rotational frequency. In period stall, sudden intensive channel observed named as component broadband frequency, its corresponding mechanism explained vortex evolution between adjacent blades based dynamic mode decomposition technology. There three distinct frequency: (i) intermittent occurrence cell propagated current channel, (ii) wide range varying rate, (iii) considerable amplitude, e.g., reaching 21.1%–42.2% that addition, both amplitude gradually decreased increased 0.887QBEP. This study clarified internal behaviors if occurred, which important assess stability units.

Язык: Английский

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Numerical investigation of energy dissipation and vortex characteristics on the S-shaped region of a reversible pump-turbine

Journal of Energy Storage, Год журнала: 2024, Номер 99, С. 113447 - 113447

Опубликована: Авг. 29, 2024

Язык: Английский

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