Comprehensive experimental and numerical analysis of instability phenomena in pump turbines

Gentner, Ch; Sallaberger, Manfred; Widmer, Ch; Bobach, Billy-Joe; Jaberg, Helmut; Schiffer, Jürgen; Senn, Florian; Guggenberger, Mark

doi:10.1088/1755-1315/22/3/032046

Cited by 26 publications

(12 citation statements)

References 1 publication

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“…Gentner et al 53 further found that this vortex structure is induced by the cross flow from the hub to the shroud at the leading edge. Figure 8 of Gentner et al 53 shows the amplitude of the secondary flow in the vaneless space based on particle image velocimetry (PIV) measurement, in which the averaged circumferential velocity has been subtracted. Near runway, the secondary flow is strong in two regions: one at the leading edges and another one at the center of blade channel.…”

Section: Vortex Formationmentioning

confidence: 95%

“…The elimination of the vortex structure at specific sites can be also employed as a design criteria of pump turbine. Gentner et al 53 proposed that the S-shaped characteristics at some guide vane openings can be eliminated by avoiding the formation of such kind of leading-edge vortex at runaway during the design stage. Gentner et al 53 further found that this vortex structure is induced by the cross flow from the hub to the shroud at the leading edge.…”

Section: Vortex Formationmentioning

confidence: 99%

“…Gentner et al 53 proposed that the S-shaped characteristics at some guide vane openings can be eliminated by avoiding the formation of such kind of leading-edge vortex at runaway during the design stage. Gentner et al 53 further found that this vortex structure is induced by the cross flow from the hub to the shroud at the leading edge. Figure 8 of Gentner et al 53 shows the amplitude of the secondary flow in the vaneless space based on particle image velocimetry (PIV) measurement, in which the averaged circumferential velocity has been subtracted.…”

Section: Vortex Formationmentioning

confidence: 99%

See 2 more Smart Citations

A review of rotating stall in reversible pump turbine

Zhang

2016

Proceedings of the Institution of Mechanical Engineers, Part C:

139

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Currently, operations of reversible pump turbines in pumped hydro energy storage plant suffer great instability problems in the well-known S-shaped characteristic regions, leading to the failure of start, significant pressure fluctuations, and severe vibrations of the whole system. One of the physical origins of the above instability of reversible pump turbines is the rotating stall phenomenon generated at off-design conditions in generating mode. In this review, recent studies on the rotating stall of reversible pump turbines are critically reviewed with a focus on the generating mode. In reversible pump turbine, the rotating stall initiates at runaway and is fully developed at low discharge condition with characteristic rotating frequency being 50-70% of the impeller rotational frequency. Notorious effects induced by rotating stall include generation of large pressure fluctuation, channel blockage, and strong backflow, all of which contribute significantly to the instability of reversible pump turbine. Methods for identification of rotating stall are also introduced with plenty of examples. Finally, several suggestions on the future work are given and discussed.

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Section: Vortex Formationmentioning

confidence: 95%

Section: Vortex Formationmentioning

confidence: 99%

Section: Vortex Formationmentioning

confidence: 99%

See 1 more Smart Citation

A review of rotating stall in reversible pump turbine

Zhang

2016

Proceedings of the Institution of Mechanical Engineers, Part C:

139

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“…Staubli [11] pointed out that the instability of S characteristic area is related to the slope of the unit characteristic curve under no-load conditions. Gentner [12] found that the blocking effect of the vortex flow in the vaneless zone under no-load opening is an important source of the instability of the S area. The study of vortex flow in the vaneless zone has also been reported by many scholars [13][14][15].…”

Section: Introductionmentioning

confidence: 99%

Analysis of Internal Flow Characteristics of a Startup Pump Turbine at the Lowest Head under No-Load Conditions

Wang

Wang²,

Wang

et al. 2021

JMSE

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The instability of the no-load working condition of the pump turbine directly affects the grid connection of the unit, and will cause vibration and damage to the components of the unit in severe cases. In this paper, a three-dimensional full flow numerical model including the runner gap and the pressure-balance pipe was established. The method SST k-ω model was used to predict the internal flow characteristics of the pump turbine. The pressure pulsation of the runner under different operating conditions during the no-load process was compared. Because the rotation speed, flow rate, and guide vane opening of the unit change in a small range during the no-load process, the pressure pulsation characteristics of the runner are basically the same. Therefore, a working condition was selected to analyze the transient characteristics of the flow field, and it was found that there was a high-speed ring in the vaneless zone, and a stable channel vortex was generated in the runner flow passage. Analyzing the axial water thrust of each part of the runner, it was found that the axial water thrust of the runner gap was much larger than the axial water thrust of the runner blades, and it changed with time periodically. It was affected by rotor stator interaction. The main frequency was expressed as a multiple of the number of guide vanes, that is, vanes passing frequency, 22fn. During the entire no-load process, the axial water thrust of the runner changed slowly with time and fluctuated slightly.

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“…Hasmatuchi 17 found in the experiment that the pressure fluctuation of a turbine in the guide vane region will increase, and the low frequency component in the pressure fluctuation will increase evidently when the turbine steps into the ''S'' region. Gentner et al 18,19 has evaluated several CFD procedures with different approaches for the calculation of the described instabilities in pump and turbine operation. Sun et al 20 Studied the S character of a pump turbine with discrete-event simulation (DES) model.…”

Section: Introductionmentioning

confidence: 99%

Investigation into the flow details of runner region in a pump turbine at off-design conditions

Gong

Wang

et al. 2016

Advances in Mechanical Engineering

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Due to the rapid development of large thermal power stations and nuclear power stations, it requires that the power grid should provide greater capability and flexibility. Security, stability, and economy in operation should also be taken into consideration. The pumped storage power station which has double peak regulating capability is a good choice to realize this goal. However, the existence of S shape characteristic of a pump turbine in generating mode at off-design condition makes it difficult to connect to the power grid. So it is necessary to analyze the reason of S shape characteristic in pump turbine by experimental investigation and numerical simulations. To achieve the above-mentioned object, numerical simulations of a pump turbine's internal flow field were performed. The generating mode was analyzed by unsteady computational fluid dynamics simulation. The evolution of flow details in runner regions under the S shape characteristic conditions was observed by changing the guide vane opening. The unsteady flow structure and load on the blades in regions of S shape characteristic were obtained, which will contribute to the design of hydro-turbine.

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Comprehensive experimental and numerical analysis of instability phenomena in pump turbines

Cited by 26 publications

References 1 publication

A review of rotating stall in reversible pump turbine

A review of rotating stall in reversible pump turbine

Analysis of Internal Flow Characteristics of a Startup Pump Turbine at the Lowest Head under No-Load Conditions

Investigation into the flow details of runner region in a pump turbine at off-design conditions

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