Flow-Induced Pulsation and Vibration in Hydroelectric Machinery

Dörfler, Peter; Coutu, André; Sick, Mirjam

doi:10.1007/978-1-4471-4252-2

Cited by 184 publications

(122 citation statements)

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“…Strong pressure pulsations, instabilities in the draft tube and excessive turbulence can generate excessive vibration levels and stresses that can damage the machine [3][4][5][6]. Flow instabilities are basically caused by the interaction of the vortex rope produced in the draft tube with the overall system [7][8][9].…”

Section: Introductionmentioning

confidence: 99%

Extension of Operating Range in Pump-Turbines. Influence of Head and Load

Valero

Egusquiza

et al. 2017

Energies

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Due to the increasing share of new renewable energies like wind and solar in the generation of electricity the need for power regulation and energy storage is becoming of paramount importance. One of the systems to store huge amounts of energy is pumped storage using reversible hydropower units. The machines used in these power plants are pump-turbines, which can operate as a pump and as a turbine. The surplus of electrical energy during low consumption hours can be converted into potential hydraulic energy by pumping water to a higher level. The stored energy can be converted into electricity again by operating the runner as a turbine. Due to new regulation requirements machines have to extend the operating range in order to match energy generation with consumption for the grid stability. In this paper the consequences of extending the operating range in existing pump-turbines have been studied. For that purpose, the data obtained after two years of condition monitoring were analyzed. Vibrations and pressure fluctuations of two pump-turbines of 85 MW each have been studied during pump and turbine operation. For turbine operation the effects of extending the operating range from the standard range of 45-85 MW to and increased range of 20-85 MW were analyzed. The change in vibration levels and signatures at very low load are presented with the identification of the phenomena that occur under these conditions. The influence of head in the vibration behavior is also presented. The appearance of fluid instabilities generated at part load that may produce power swing is also presented. Finally, the effect of head on the vibration levels for pump operation is shown and analyzed.

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Section: Introductionmentioning

confidence: 99%

Extension of Operating Range in Pump-Turbines. Influence of Head and Load

Valero

Egusquiza

et al. 2017

Energies

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“…There are several special countermeasures for reducing these pulsations. Air admission is the most widely used method [3]. However, this method is too expensive in case of static pressure at the aeration point exceeding atmospheric pressure.…”

Section: Introductionmentioning

confidence: 99%

The study of the influence of stabilizing devices on the pressure pulsations at the free discharge of water through the turbine

2017

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Abstract. The free discharge through the turbine is applied in the course of construction of hydro power plant or in case of excessive water inflow during floods or emergency situations. The experimental and numerical investigation of flow-induced pressure pulsations in hydraulic turbine draft tube at free discharge was performed using a special setup for suppression of draft tube surge. Such special equipment in draft tube cone as fins and "spider"-like units was considered for reducing these pressure pulsations. The paper considers influence of these units on vortex structures and pressure pulsations in the draft tube in several regimes.

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“…To name a few, the large pressure fluctuations caused by vortex rope in draft tube often happen at 30%∼60% of rated load, the vibration induced by Kármán vortex shedding from the blades occurs at over 50% of rated load, and also the channel vortices between the neighboring blades appear accompanying cavitation, and so forth [1].…”

Section: Introductionmentioning

confidence: 99%

“…Their mutual interaction was responsible for the dynamic load, the resulting stress, and residual life of the turbine components [2]. This phenomenon often had sufficiently high frequency to be perceived as noise and vibration, depending on the numbers of stationary and rotating cascades [1]. The associated pressure pulsation would excite natural frequency of system, resulting in standing wave in the spiral casing.…”

Section: Introductionmentioning

confidence: 99%

“…Lais et al (2008) also did experiments and simulation to study the natural frequencies, accompanying the fluid-structure interaction [30]. Those results revealed that the highest amplitude of Advances in Mechanical Engineering 3 pressure variations occurred in the region of the vaneless gap between the stationary and rotary cascades, and it decreased rapidly with the distance from that area [1,31].…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

On the Flow Instabilities and Turbulent Kinetic Energy of Large-Scale Francis Hydroturbine Model at Low Flow Rate Conditions

et al. 2014

Advances in Mechanical Engineering

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This paper is to make a better understanding of the flow instabilities and turbulent kinetic energy (TKE) features in a largescale Francis hydroturbine model. The flow instability with aspect of pressure oscillation and pressure-velocity correlation was investigated using large eddy simulation (LES) method along with two-phase cavitation model. The numerical simulation procedures were validated by the existing experimental result, and further the TKE evolution was analyzed in a curvilinear coordinates. By monitoring the fluctuating pressure and velocities in the vanes' wake region, the local pressure and velocity variations were proven to have a phase difference approaching /2, with a reasonable cross-correlation coefficient. Also the simultaneous evolution of pressure fluctuations at the opposite locations possessed a clear phase difference of , indicating the stresses variations on the runner induced by pressure oscillation were in an odd number of nodal diameter. Considering the TKE generation, the streamwise velocity component ⟨ 2 ⟩ contributed the most to the TKE, and thus the normal stress production term and shear stress production term imparted more instability to the flow than other production terms.

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Flow-Induced Pulsation and Vibration in Hydroelectric Machinery

Cited by 184 publications

References 0 publications

Extension of Operating Range in Pump-Turbines. Influence of Head and Load

Extension of Operating Range in Pump-Turbines. Influence of Head and Load

The study of the influence of stabilizing devices on the pressure pulsations at the free discharge of water through the turbine

On the Flow Instabilities and Turbulent Kinetic Energy of Large-Scale Francis Hydroturbine Model at Low Flow Rate Conditions

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