On the relation between friction losses and pressure pulsations caused by Rotor Stator interaction on the Francis-99 turbine

Østby, Petter Thorvald Krogh; Billdal, Jan Tore; Haugen, Bjørn Olav; Dahlhaug, Ole Gunnar

doi:10.1088/1742-6596/782/1/012010

Cited by 2 publications

(3 citation statements)

References 3 publications

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“…e pressure amplitudes show a small increasing trend which may be to some extent related to Reynolds effects [27,28]. e IEC 60193 [21] recommends the Reynolds number (Re D2 ) to be above 5 • 10 6 to avoid Reynolds dependencies in the model measurements.…”

Section: Resultsmentioning

confidence: 99%

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Experimental Study of a Low‐Specific Speed Francis Model Runner during Resonance

Agnalt

Østby

Solemslie

et al. 2018

Shock and Vibration

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An analysis of the pressure in a runner channel of a low-specific speed Francis model runner during resonance is presented, which includes experiments and the development of a pressure model to estimate both the convective and acoustic pressure field from the measurements. The pressure was measured with four pressure sensors mounted in the runner hub along one runner channel. The mechanical excitation of the runner corresponded to the forced excitation from rotor-stator interaction. The rotational speed was used to control the excitation frequency. The measurements found a clear resonance peak in the pressure field excited by the second harmonic of the guide vane passing frequency. From the developed pressure model, the eigenfrequency and damping were estimated. The convective pressure field seems to diminish almost linearly from the inlet to outlet of the runner, while the acoustic pressure field had the highest amplitudes in the middle of the runner channel. At resonance, the acoustic pressure clearly dominated over the convective pressure. As the turbine geometry is available to the public, it provides an opportunity for the researchers to verify their codes at resonance conditions.

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Section: Resultsmentioning

confidence: 99%

“…e measurement data and geometry used to support the findings of this study are available at the Francis-99 website [28].…”

Section: Abbreviationsmentioning

confidence: 95%

Experimental Study of a Low‐Specific Speed Francis Model Runner during Resonance

Agnalt

Østby

Solemslie

et al. 2018

Shock and Vibration

View full text Add to dashboard Cite

show abstract

“…The nature of the rotor stator interaction is well described in the literature and commonly divided into the effect from potential flow interaction and viscous wake interaction [3][4][5][6]. The potential flow effect is related to the accelerated flow in the cascade, and the low-and high-pressure side of the guide vanes [7]. The viscous wake effect is the defects in the flow field affecting the velocity distribution at the runner inlet [8].…”

Section: Introductionmentioning

confidence: 99%

The Rotor-Stator Interaction Onboard A Low Specific Speed Francis Turbine

Agnalt

Solemslie

Storli

et al. 2020

IJFMS

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Over the last years, several breakdowns in hydropower plants with low specific speed Francis runners have been reported. One of the main excitation forces in such runners is the pressure fluctuations originating from the rotor stator interaction. In this paper, the rotor-stator interaction has been analyzed utilizing pressure sensors onboard the runner. The pressure sensors were flush mounted in the hub of the runner and the signals were transmitted through a slip-ring system. The measurements have been analyzed relative to the runner angular position by utilizing an angular position sensor mounted to the shaft end. Measurements with different guide vane angle have been compared in order to study the potential flow interaction and the viscous wake effects for the pressure inside the runner. The results from the onboard pressure measurements found that the phase of the guide vane passing pressure seen by the onboard pressure sensors was independent of the guide vane opening. Hence, the potential flow interaction was found to be the dominant effect and no evidence from the viscous wake effect was found on the onboard pressure.

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On the relation between friction losses and pressure pulsations caused by Rotor Stator interaction on the Francis-99 turbine

Cited by 2 publications

References 3 publications

Experimental Study of a Low‐Specific Speed Francis Model Runner during Resonance

Experimental Study of a Low‐Specific Speed Francis Model Runner during Resonance

The Rotor-Stator Interaction Onboard A Low Specific Speed Francis Turbine

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