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Article

Leakage Vortex Progression through a Guide Vane’s Clearance Gap and the Resulting Pressure Fluctuation in a Francis Turbine

1
Waterpower Laboratory, Department of Energy & Process Engineering, Norwegian University of Science and Technology, NO-7491 Trondheim, Norway
2
Turbine Testing Lab, Kathmandu University, Dhulikhel 45210, Nepal
*
Author to whom correspondence should be addressed.
Academic Editor: Helena M. Ramos
Energies 2021, 14(14), 4244; https://doi.org/10.3390/en14144244
Received: 11 June 2021 / Revised: 5 July 2021 / Accepted: 7 July 2021 / Published: 14 July 2021
A clearance gap (CG) between guide vanes (GVs) and facing plates exists at both ends of a Francis turbine and allows the opening angle to be adjusted for varying operating conditions. Leakage flow is induced through this gap due to the pressure difference between the two sides of the guide vanes. While some research works have used qualitative approaches to visualize and predict the strength of a leakage vortex (LV), this paper presents a method for quantifying vortices along a trajectory. In this paper, a prototype high-head Francis runner with specific speed of 85.4 is considered as a reference case. A systematic investigation across both space and time is carried out, i.e., analysis of the spatial temporal progression of LV for three operating conditions. While travelling from the CG to runner leading edge, LV evolution and trajectory data are observed and the values of vorticity and turbulent kinetic energy are calculated for the LV trajectory. Frequency spectrum analyses of pressure oscillations in the vaneless space, runner blade, and draft tube are also performed to observe the peak pressure pulsation and its harmonics. Unsteady fluctuations of the runner output torque are finally studied to identify the patterns and magnitudes of torque oscillations. View Full-Text
Keywords: clearance gap; leakage vortex; rotor stator interaction; pressure pulsation clearance gap; leakage vortex; rotor stator interaction; pressure pulsation
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MDPI and ACS Style

Acharya, N.; Gautam, S.; Chitrakar, S.; Trivedi, C.; Dahlhaug, O.G. Leakage Vortex Progression through a Guide Vane’s Clearance Gap and the Resulting Pressure Fluctuation in a Francis Turbine. Energies 2021, 14, 4244. https://doi.org/10.3390/en14144244

AMA Style

Acharya N, Gautam S, Chitrakar S, Trivedi C, Dahlhaug OG. Leakage Vortex Progression through a Guide Vane’s Clearance Gap and the Resulting Pressure Fluctuation in a Francis Turbine. Energies. 2021; 14(14):4244. https://doi.org/10.3390/en14144244

Chicago/Turabian Style

Acharya, Nirmal, Saroj Gautam, Sailesh Chitrakar, Chirag Trivedi, and Ole G. Dahlhaug 2021. "Leakage Vortex Progression through a Guide Vane’s Clearance Gap and the Resulting Pressure Fluctuation in a Francis Turbine" Energies 14, no. 14: 4244. https://doi.org/10.3390/en14144244

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