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Fluid Mechanics in Hydraulic Turbines

A special issue of Applied Sciences (ISSN 2076-3417). This special issue belongs to the section "Mechanical Engineering".

Deadline for manuscript submissions: closed (31 May 2022) | Viewed by 4777

Special Issue Editors


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Guest Editor
Research Institute of Hydro-Québec (IREQ) 1800, boul. Lionel-Boulet Varennes (Québec) J3X 1S1, Canada
Interests: hydropower; turbomachines; hydraulic turbines; cavitation; flow instabilities; hydro-acoustic
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Guest Editor
Department of Energy and Process Engineering, Faculty of Engineering, Norwegian University of Science and Technology, Waterpower laboratory, Alfred Getz vei 4, 7491 Trondheim, Norway
Interests: renewable energy; hydropower; fluid mechanics; computational fluid dynamic; fluid structure interaction
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

The future energy market aims for high flexibility that allows guaranteed power to consumers with a minimum carbon footprint. In this context, hydropower will play a key role by providing low-carbon electricity production on one hand, and ancillary services to the energy market to compensate for the intermittent production by renewable energy sources on the other hand. This, however, means increasing start and stop sequences, speed no-load, and off-design operations of hydraulic turbines, where they are subject to the development of complex unsteady flow phenomena, flow-induced vibrations, and cavitation. A better understanding, control, and prediction of the latter are crucial to ultimately improve the reliability and flexibility of hydraulic turbines.

This Special Issue targets recent experimental and numerical investigations contributing to all aspects of fluid mechanics in hydraulic turbines, including, but not limited to, understanding and prediction of the fundamental dynamics of hydraulic turbine internal flow, development of flow control methods, flow-induced vibrations, and fluid–structure interaction. Investigations on simplified test-cases, conventional hydraulic turbines, and tidal turbines are welcome.

We look forward to receiving your contribution.

Dr. Arthur Tristan Favrel
Dr. Chirag Trivedi
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Applied Sciences is an international peer-reviewed open access semimonthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2400 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • hydraulic turbines
  • fluid dynamics
  • experimental techniques
  • numerical simulations
  • active and passive flow control
  • flow-induced vibrations
  • fluid–structure interaction

Published Papers (2 papers)

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Research

24 pages, 114783 KiB  
Article
Analysis of the Mode Shapes of Kaplan Runners
by Greco Moraga, Mònica Egusquiza, David Valentín, Carme Valero and Alexandre Presas
Appl. Sci. 2022, 12(13), 6708; https://doi.org/10.3390/app12136708 - 2 Jul 2022
Cited by 2 | Viewed by 1998
Abstract
To prevent lifetime shortening and premature failure in turbine runners, it is of paramount importance to analyse and understand its dynamic response and determine the factors that affect it. In this paper, the dynamic response of a Kaplan runner is analysed in air [...] Read more.
To prevent lifetime shortening and premature failure in turbine runners, it is of paramount importance to analyse and understand its dynamic response and determine the factors that affect it. In this paper, the dynamic response of a Kaplan runner is analysed in air by numerical and experimental methods. First, to start the analysis of Kaplan runner mode shapes, its geometry is simplified and modelled as a bladed disk. Bladed disks with different blade numbers are investigated, by numerical simulation, in order to understand the influence of this parameter on its modal characteristics. Then, mode shapes extracted are characterized and a classification is proposed. Second, an existing Kaplan runner is simulated by Finite Elements Method (FEM) and its mode shapes are extracted. The obtained results are contrasted with the bladed disks mode shapes, in order to validate the classification proposed. The simulated Kaplan runner is also experimentally studied. A numerical modal analysis is carried out in the real runner. Different, global and local, mode shapes are identified. The global mode shapes extracted by numerical and experimental modal analysis are compared and discussed. Finally, the local mode shapes identified are commented and explained by means of numerical simulation. Full article
(This article belongs to the Special Issue Fluid Mechanics in Hydraulic Turbines)
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15 pages, 6444 KiB  
Article
Modal Decomposition of the Precessing Vortex Core in a Hydro Turbine Model
by Ivan Litvinov, Dmitriy Sharaborin, Evgeny Gorelikov, Vladimir Dulin, Sergey Shtork, Sergey Alekseenko and Kilian Oberleithner
Appl. Sci. 2022, 12(10), 5127; https://doi.org/10.3390/app12105127 - 19 May 2022
Cited by 10 | Viewed by 1625
Abstract
We report on the experimental study of a precessing vortex core (PVC) in an air model of a Francis turbine. The focus is placed on the modal decomposition of the PVC that occurs in the draft tube of the model turbine for a [...] Read more.
We report on the experimental study of a precessing vortex core (PVC) in an air model of a Francis turbine. The focus is placed on the modal decomposition of the PVC that occurs in the draft tube of the model turbine for a range of operation conditions. The turbulent flow fluctuations in the draft tube are assessed using stereo particle image velocimetry (PIV) measurements. Proper orthogonal decomposition (POD) is applied to the antisymmetric and symmetric components of the velocity fields to distinguish the dynamics of the azimuthal instabilities. The pressure pulsations induced by the PVC are measured by four pressure sensors mounted on the wall of the hydro turbine draft tube. Spatial Fourier decomposition is applied to the signals of the pressure sensors to identify the contributions of azimuthal modes, m=1 and m=2, to the total pressure fluctuations. The analysis based on velocity and pressure data shows similar results regarding the identification of the PVC. The contribution of the m=2 mode to the overall turbulent kinetic energy is significant for the part load regimes, where the flow rates are twice as low as at the best efficiency point (BEP). It is also shown that this mode is not the higher harmonic of the PVC, suggesting that it is driven by a different instability. Finally, we show a linear fit of the saturation amplitudes of the m=1 and m=2 oscillations to determine the critical bifurcation points of these modes. This yields critical swirl numbers of Scr=0.47 and 0.61, respectively. The fact that the PVC dynamics in hydro turbines are driven by two individual instabilities is relevant for the development of tailored active flow control of the PVC. Full article
(This article belongs to the Special Issue Fluid Mechanics in Hydraulic Turbines)
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