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Home > News > Ph.D. Thesis > Ph.D. Thesis 2021

Thursday, March 25, 2021, Matthieu GUILBOT’s thesis defense - 2:00 PM, Room G128, LEGI, Bergès site

Analysis and optimization of vertical-axis and cross-flow turbines performance with numerical computations

This thesis has been directed by G. Balarac. and S. Barre & C. Bonamy. This work was supported by the company HydroQuest (CIFRE) and N. Guillaud was the industrial contact.

Abstract :
This thesis focuses on the analysis and optimization of the performances of a vertical-axis and cross-flow turbine (VAT) by means of numerical simulations. The highly
unsteady and turbulent nature of the flows involved inside a VAT makes their modeling complex. Several numerical methods with distinct turbulence approaches have
therefore been used in order to evaluate VAT performances. URANS simulations and Large-Eddy Simulations (LES) have been performed with OpenFoam and YALES2, respectively. To improve the VAT design, two lines of research were investigated. Initially, a single-rotor configuration was optimized using LES by studying two specific rotor geometries: a “classic” H-shape Darrieus rotor and an “innovative” rotor. This study provided a better understanding of the overall flow dynamics within a VAT according to the flow regime. Thanks to a local loss analysis, the performances gap between both rotors was quantified. A good agreement with experimental observations was found, in particular a gain of the “innovative” rotor of about +30% on the power coefficient (Cp). Secondly, several double-rotor configurations, each consisting of two counter-rotating rotors, were optimized through URANS simulations. Various geometric parameters (inter-axis distance, counter-rotational direction, central mast) were tested in order to maximize the total power extracted by the machine. A “synergy” effect was observed in twin-rotor configuration leading to a power gain of around +10% compared to a single-rotor VAT. A detailed flow analysis linked the optimal counter-direction with the turbine solidity. This work, carried out in
collaboration with the HydroQuest company, has then led to a local performance optimization, by directly modifying the design of the rotor and a more global enhancement on double-rotor configurations tending towards the optimization of a wind/tidal farm.

Membres du jury :
- Mme. Sandrine AUBRUN, Professeure des Universités, École Centrale de Nantes, Examinatrice
- M. Christophe CORRE, Professeur des Universités, École Centrale de Lyon, Examinateur
- M. Éric GONCALVES, Professeur des Universités, ISAE-ENSMA, Rapporteur
- M. Dominique THEVENIN, Professeur des Universités, Université de Magdebourg, Rapporteur
- M. Guillaume BALARAC, Maître de Conférences, Grenoble INP, Directeur de thèse
- M. Stéphane BARRE, Chargé de Recherche, CNRS, Codirecteur de thèse
- M. Cyrille BONAMY, Ingénieur de Recherche, CNRS, Membre invité
- M. Nathanaël GUILLAUD, Ingénieur R&D, HydroQuest, Membre invité