Numerical simulation and analysis at partial load in Francis turbines: Three-dimensional topology and frequency signature of inter-blade vortices

Doussot, François; Balarac, Guillaume; Brammer, James; Métais, Olivier; Ségoufin, Claire

doi:10.1088/1755-1315/240/2/022045

Cited by 6 publications

(2 citation statements)

References 4 publications

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“…The EPFL thus showed that the amplitude of the pressure fluctuation on the blade's suction surface was enhanced significantly [7]. Voith Hydroelectric in Germany and General Electric in France also confirmed experimentally that the development of the inter-blade vortex imposes an enhancement effect on the amplitude of the pressure fluctuation on the suction surface of the runner blade [8,9]. The numerical study of Xiao et al [10,11] showed that the frequency of pressure pulsation induced by the inter-blade vortex was 0.2-3.0 times higher than that induced by rotational frequencies.…”

Section: Introductionmentioning

confidence: 68%

Particle Image Velocimetry Test for the Inter-Blade Vortex in a Francis Turbine

Jin²,

et al. 2021

Processes

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Hydropower units are usually operated in non-design conditions because of power grid requirements. In a partial-load condition, an inter-blade vortex phenomenon occurs between the runner blades of a Francis turbine, causing pressure pulsation and unit vibration, which hinder the safe and stable operation of power stations. However, the mechanism through which the inter-blade vortex generation occurs is not entirely clear. In this study, a specific model of the Francis turbine was used to investigate and visually observe the generation of the blade vortex in Francis turbines in both the initial inter-blade and vortex development zones. Particle image velocimetry was used for this purpose. In addition, we determined the variation law of the inter-blade vortex in the Francis turbine. We found that the size and strength of the inter-blade vortex depend on the unit speed of the turbine. The higher the unit speed is, the stronger the inter-blade vortex becomes. We concluded that the inter-blade vortex of such turbines originates from the pressure surface or secondary flow and stall of the blade at the inlet side of the runner at high unit speeds, and also from the backflow zone of the suction surface of the blade at low unit speeds.

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Section: Introductionmentioning

confidence: 68%

Particle Image Velocimetry Test for the Inter-Blade Vortex in a Francis Turbine

Jin²,

et al. 2021

Processes

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“…Since this paper does not focus on secondary flows, a detailed description of all the possible secondary flows is avoided. Detailed information on secondary flows occurring in Francis turbines and in reversible pump turbines operating at off-design conditions can be found in references [54][55][56][57] In this scenario, IDM adoption could limit the development of the interblade vortexes by modifying the flow incidence condition. Moreover, the control of the static pressure distribution represents an effective method for the suppression of cavitation phenomena without compromising the hydraulic efficiency.…”

Section: The Idm and The Suppression Of Secondary Flowsmentioning

confidence: 99%

Application of the 3D Inverse Design Method in Reversible Pump Turbines and Francis Turbines

Zanetti

Siviero

Cavazzini

et al. 2023

Water

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The increasingly stringent requirements in terms of flexibility and efficiency for hydraulic turbines pose new challenges for designers. Although computational fluid dynamics has offered new opportunities to significantly improve the performance in the preliminary design phase, the design of a hydraulic turbine still represents a challenging task requiring considerable engineering input and know-how. In such a scenario, the inverse three-dimensional design strategy has recently demonstrated its effectiveness in improving the machine performance, and interesting applications have been proposed for Francis turbines and reversible pump turbines. This paper presents and discusses the most interesting design solutions so far documented. The influence of blade staking and load distribution on the hydrodynamic performance is discussed. Finally, optimized blade load distributions are reported to provide useful design guidelines for the development of the new generation of hydraulic turbines.

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2020

Numerical Simulation, an Art of Prediction 2

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Numerical simulation and analysis at partial load in Francis turbines: Three-dimensional topology and frequency signature of inter-blade vortices

Cited by 6 publications

References 4 publications

Particle Image Velocimetry Test for the Inter-Blade Vortex in a Francis Turbine

Particle Image Velocimetry Test for the Inter-Blade Vortex in a Francis Turbine

Application of the 3D Inverse Design Method in Reversible Pump Turbines and Francis Turbines

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