Publications de François Avellan

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The most exploited renewable energy at a global scale is hydropower, which nowadays accounts for the 18 % of the world’s electricity supply. Its production is expected to increase approximately 3.1% each year in the next 25 years maintaining its share in t ...

The mechanical design of hydraulic turbines is conditioned by the dynamic response of the runner that is usually estimated by a computational model. Nevertheless, the runner has complex boundary conditions that are difficult to include in the computational ...

Investigation of the rotor-stator interactions of a reduced-scale model 0.19 ν= pump-turbine in generating mode is presented for the maximum discharge operating condition. This operating point is chosen in order to have the most important rotor-stator inte ...

The complex three-dimensional unsteady flow developing in the draft tube of a Francis turbine is responsible for pressure fluctuations, which could prevent the whole hydropower plant from operating safely. Indeed, the Francis draft tube is subjected to inl ...

Combined effect of rotating pressure field related to runner blade and wakes of wicket gates leads to rotor stator interactions, RSI, in Francis pump-turbines. These interactions induce pressures waves propagating in the entire hydraulic machine. Superposi ...

The paper reviews recent research and development activities in the field of hydropower technology. It covers emerging and advanced technologies to mitigate flow instabilities (active and passive approach) as well as emerging magneto-rheological control te ...

In the framework of the XFLEX HYDRO H2020 European Project, one of the demonstrators focuses on the implementation of the hydraulic short-circuit on the pump storage power plant of Grand-Maison owned by Electricite De France (EDF). The Grand-Maison power p ...

Francis turbines operating at part load condition experience the development of a cavitating helical vortex rope in the draft tube cone at the runner outlet. The precession movement of this vortex rope induces local convective pressure fluctuations and a s ...

The required operating range for hydraulic machines is continually extended in an effort to integrate renewable energy sources with unsteady power outputs into the existing electrical grid. The off-design operation however brings forth unfavorable flow pat ...

The present study deals with the shedding process of the von Kármán vortices at the trailing edge of a 2D hydrofoil at high Reynolds number. This research focuses mainly on the effects of cavitation and fluid-structure interaction on the mechanism of the v ...

Scale model of high specific speed Francis turbines may present at upper part load operation under low cavitation number pressure fluctuation in the range 2 to 4 times fn, the rotating frequency. In the framework of the FLINDT project, pressure measurements on the draft tube wall of a Francis turbine scale model at 104 locations revealed such phenomenon at a frequency of almost 2.5 fn. The phase shift analysis of the measured pressure fluctuations in the draft tube at this frequency points out a pressure so

For the design optimization of the Pelton turbine, it is highly demanded to investigate the flow inside the turbine casing, which includes the water jet from the nozzles, the interaction between the jet and rotating runner, and the flow ejected from the bu ...

Hydroelectric power plants are known for their ability to cover variations of the consumption in electrical power networks. In order to follow this changing demand, hydraulic machines are subject to off-design operation. In that case, the swirling flow lea ...

Fluid-structure investigations in hydraulic machines using coupled simulations are extremely time-consuming; therefore we develop an alternative method. In this paper, a model is proposed to predict fluid-structure coupling by linearizing the hydrodynamic ...

All hydraulic turbines containing a casing with stay vanes face the potential dynamic problem of stay vane von Kármán vortex shedding. For hydraulic efficiency purposes the stay vanes tend to be relatively slender in the direction normal to the flow thus b ...

The Z'Mutt pumping station, part of the Grande Dixence hydroelectric scheme, is one of the demonstrators of the XFLEX HYDRO project. A 5 MW reversible pump-turbine prototype equipped with a full-size frequency converter (FSFC) is used to investigate dynami ...

With the Energy Strategy 2050, Switzerland wishes to focus on balanced utilization of hydropower potentials and new renewable energy sources to cope with nuclear energy phasing out. Integration of large amounts of new renewable energies such as wind and so ...

The roles of hydropower plants within the energy system has been evolving during the last two decades. The potential to provide ancillary services to the grid is often harnessed, leading to a major change in hydropower plants operations. Ancillary services ...

The technical capacity to predict the erosion process is instrumental for the optimization of the runner designs and operation strategies of hydroelectric plants. A multiscale model of erosion recently formulated by the authors and validated on a laborator ...

Modern pump-turbines are subject to frequent switching between the pumping and generating modes with extended operation under off-design conditions. Depending on the specific speed of the pump-turbine, the discharge-speed as well as torque-speed characteristics at constant guide vanes opening can be “S-Shaped”. In this case, the machine operation may become strongly unstable at runaway speed and beyond, with a significant increase of structural vibrations and noise. In the present work, hydrodynamics of a l

François Avellan

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Experimental evaluation of the velocity profiles and performance of a counter rotating micro-turbine by 2D laser Doppler velocimetry

Modal Response of Hydraulic Turbine Runners

Pump-Turbine Rotor-Stator Interactions in Generating Mode: Pressure Fluctuation in Distributor Channel

Experimental Evidence of Hydroacoustic Pressure Waves in a Francis Turbine Elbow Draft Tube for Low Discharge Conditions

Hydroacoustic Simulation of Rotor-Stator Interaction in Resonance Conditions in Francis Pump-Turbine

Analysis of emerging technologies in the hydropower sector

CFD simulations of a Y-junction for the implementation of hydraulic short-circuit operating mode

Hydro-acoustic resonance behavior in presence of a precessing vortex rope: observation of a lock-in phenomenon at part load Francis turbine operation

On the physical mechanisms governing self-excited pressure surge in Francis turbines

Cavitation Influence on Kármán Vortex Shedding and Induced Hydrofoil Vibrations

Identification and Modeling of Pressure Fluctuations of a Francis Turbine Scale Model at Part Load Operation

Application of particle-based numerical analysis to the practical design of Pelton turbine

Influence of the vortex rope location of a Francis Turbine on the hydraulic system stability

Hydro Elastic Behavior of Vibrating Blades

Unsteady CFD Prediction of von Kármán Vortex Shedding in Hydraulic Turbine Stay Vanes

Turbine mode start-up simulation of a variable speed Francis pump-turbine prototype - Part II: 3-D unsteady CFD and FEM

Renovation of hydraulic power plant: how to select the best technical options?

Model testing beyond the scope of International Standards: an outlook

Multiscale simulation of erosive wear in a prototype-scale Pelton runner

Hydrodynamics of a Pump-Turbine Operating at Off-Design Conditions in Generating Mode: Experimental Investigation