Measuring the Dynamic Characteristics of a Low Specific Speed Pump—Turbine Model

Walseth, Eve Cathrin; Nielsen, Torbjørn Kristian; Svingen, B.

doi:10.3390/en9030199

Cited by 25 publications

(6 citation statements)

References 1 publication

(1 reference statement)

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“…When the pump unit is shut down due to sudden power failure or maloperation, it will eventually enter runaway mode, and when the pump unit is running in runaway mode, some parts of the pump unit may be damaged due to the mass imbalance of the rotating body and the hydraulic instability inside the unit [20]. More and more scholars have begun to conduct experiments and numerical simulation studies on the runaway mode of the pump unit [21,22]. Kan K et al [23] analyzed in detail the flow characteristics and energy loss of the internal flow field during the runaway process of an axial flow pump unit.…”

Section: Introductionmentioning

confidence: 99%

A Study on the Transient Characteristics of the Power-Off Transition Process of a Double-Volute Centrifugal Pump

Lu,

Ren,

Wang

et al. 2024

Water

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A double-volute centrifugal pump is a very important pump type; the internal flow field of a centrifugal pump will change drastically during the transition process of power failure, which will affect the safety and stability of the pump’s operation. In this paper, the CFD numerical simulation method is used, and the UDF procedure is developed to realize the continuous update of the impeller speed at each time step. The working parameters, such as the torque and flow rate at the instantaneous moment, are obtained through the sequential iteration of each small step, and a numerical simulation of the power-off transient is carried out on a double-volute centrifugal pump; additionally, the changes in the external characteristic parameters and the internal flow field of the centrifugal pump are analyzed in detail. The results show that the double-volute centrifugal pump experienced four different modes after power failure, namely pump mode, braking mode, turbine mode, and runaway mode, and the absolute values of the runaway speed and runaway flow rate are 1.465 times and 1.21 times the initial values, respectively. Through the analysis of the flow field in different regions, the change processes of the generation, development, and disappearance of the vortex at each position of the centrifugal pump are obtained, and the change and development processes of the internal velocity gradient of the centrifugal pump are obtained. In addition, it is found that the high-speed area located in the second volute runner is larger than that of the first volute runner because the second volute runner is shorter and narrower than the first volute runner.

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Section: Introductionmentioning

confidence: 99%

A Study on the Transient Characteristics of the Power-Off Transition Process of a Double-Volute Centrifugal Pump

Lu,

Ren,

Wang

et al. 2024

Water

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“…Yao et al [7] combined the load shedding conditions of the Guangzhou PSH station under different guide vane closure laws and calculated the effect of guide vane closure laws. Walseth et al [8] combined experiments and one-dimensional numerical calculations to study the pump-turbine flyaway process. Zhang et al [9] used the VOF two-phase flow model to simulate the entire flow system numerically.…”

Section: Introductionmentioning

confidence: 99%

Research on Energy Loss Characteristics of Pump-Turbine during Abnormal Shutdown

Deng¹,

Xu²,

Li³

et al. 2022

Processes

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Pumped-storage hydropower (PSH) stations are an efficient emission-free technology to balance renewable energy generation instabilities. The pump-turbine is a core component of PSH stations requiring frequent start-up, shutdown, and working conditions for regulation tasks, making it prone to instabilities. Based on entropy production theory and vortex dynamics, we analyzed the energy loss characteristics for three working conditions of the pump, pump brake, and turbine when shutting down the pump-turbine. The results showed that the entropy production and vorticity of the spiral casing and draft tube remain almost constant, while the entropy production and vorticity of the runner region substantially change from the late pump braking to the late turbine condition. The entropy production and vorticity are derived from the guide vane transitioning to the runner flow channel through the vaneless space. The change law of energy loss through entropy production agrees with the change law of internal flow turbulence through vorticity. The entropy production analysis can quantify the energy loss and mark its location, while the vorticity analysis can quantify the degree of flow disturbance and show its location. The entropy production theory and vortex dynamics combination provide insights into the connection between undesirable flow phenomena and energy loss.

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“…More fundamentally, Xia [6] found that the backflows at the runner inlet facilitate the inception and development of rotating stalls. The studies of the flow patterns on the static characteristic curves provide the basis for the loop-shaped dynamic runaway characteristic curves [7,8]. In a PSHS, the stability of the water inertia wave during runaway transients depends mainly on the characteristics of the pump-turbine, i.e.…”

Section: Introductionmentioning

confidence: 99%

Evolution and influence of high-head pump-turbine cavitation during runaway transients

Wu¹,

Liu²,

Li³

et al. 2022

IOP Conf. Ser.: Earth Environ. Sci.

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Pumped-storage hydropower stations (PSHSs) play irreplaceable roles in promoting the stability and flexibility of power grids. Runaway process is one of the most dangerous transients for PSHSs, and the cavitation in the pump-turbine seriously affects the stability and safety of the unit. However, the evolution and influence of pump-turbine cavitation during runaway transients are still unclear. In this study, the runaway transients of a high-head pump-turbine considering the cavitation effects were simulated by using the three-dimensional (3D) computational fluid dynamics (CFD) method. The results show that the cavitation cavities in the runner appear and disappear periodically, influenced by the backflows around the leading and trailing edges of the runner blades. The wedge-shaped cavities near the leading edges occur around the peak rotational speed moment when the pressure pulsations in the vaneless space show the peak magnitude. And the tongue-shaped shaped cavities near trailing edges appear around zero discharge moment when the hydraulic radial forces reach the peak. The two types of cavitation occur at dangerous moments, to which attention should be paid in the preliminary design stage of PSHSs.

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Measuring the Dynamic Characteristics of a Low Specific Speed Pump—Turbine Model

Cited by 25 publications

References 1 publication

A Study on the Transient Characteristics of the Power-Off Transition Process of a Double-Volute Centrifugal Pump

A Study on the Transient Characteristics of the Power-Off Transition Process of a Double-Volute Centrifugal Pump

Research on Energy Loss Characteristics of Pump-Turbine during Abnormal Shutdown

Evolution and influence of high-head pump-turbine cavitation during runaway transients

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