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François Avellan

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Publications associées (218)

Flow simulation of a Pelton bucket using finite volume particle method

François Avellan, Christian Vessaz, Ebrahim Jahanbakhsh

The objective of the present paper is to perform an accurate numerical simulation of the high-speed water jet impinging on a Pelton bucket. To reach this goal, the Finite Volume Particle Method (FVPM) is used to discretize the governing equations. FVPM is ...

International Association For Hydraulic Research2014

Interaction of a pulsating vortex rope with the local velocity field in a Francis turbine draft tube

François Avellan, Andres Müller, Steven Roth, Christian Landry, Matthieu Dreyer, Alberto Bullani, Arthur Tristan Favrel

Acoustic resonances in Francis turbines often define undesirable limitations to their operating ranges at high load. The knowledge of the mechanisms governing the onset and the sustenance of these instabilities in the swirling flow leaving the runner is es ...

IOP science2013

Design optimization of a 2D blade by means of milling tool path

François Avellan, Christian Vessaz, Cécile Münch-Alligné, Christophe Tournier

In a conventional design and manufacturing process, turbine blades are modeled based on reverse engineering or on parametric modeling with Computer Fluids Dynamics (CFD) optimization. Then, only raises the question of the manufacturing of the blades. As th ...

2013

Pressure pulsation in Kaplan turbines: Prototype-CFD comparison

François Avellan, Arturo Rivetti

Pressure pulsation phenomena in a large Kaplan turbine are investigated by means of numerical simulations (CFD) and prototype measurements in order to study the dynamic behavior of flow due to the blade passage and its interaction with other components of ...

International Association For Hydraulic Research2012

Modeling of Unsteady Friction and Viscoelastic Damping in Piping Systems

François Avellan, Christophe Nicolet, Andres Müller, Christian Landry

In real systems, the phenomena, such as pipe-wall viscoelasticity, unsteady friction or fluid structure interaction induce additional damping and dispersion of transient pressure waves than that defined by classical waterhammer. In this paper, unsteady fri ...

International Association For Hydraulic Research2012

Simulation of water column separation in Francis pump-turbine draft tube

François Avellan, Christophe Nicolet, Sébastien Alligné

The paper presents the modelling, simulation and analysis of the transient behaviour of a 340 MW pump-turbine in case of emergency shutdown in turbine mode with focus on possible draft tube water column separation. The model of a pumped storage power plant ...

International Association For Hydraulic Research2012

Analysis of the dynamic response of pump-turbine runners- Part I: Experiment

François Avellan, Mohamed Farhat, Eduard Egusquiza, Xiaopeng Huang

When in operation, pump-turbine runners have to withstand large pressure pulsations generated by the rotor-stator interaction. The analysis of the dynamic behavior of these structures is necessary to avoid damage. For this analysis a realistic model of the ...

International Association For Hydraulic Research2012

Cavitation influence on hydroacoustic resonance in pipe

François Avellan, Christophe Nicolet, Nicolas Ruchonnet, Sébastien Alligné

In pipe systems, pressure and flow fluctuations below cutoff frequency propagate as plane waves along pipes. Depending on the pipe length and propagation velocity, resonance leading to high amplitude pressure fluctuation may occur. At low pressure, cavitat ...

Elsevier2012

The Effects of a Tripped Turbulent Boundary Layer on Vortex Shedding from a Blunt Trailing Edge Hydrofoil

François Avellan, Mohamed Farhat, Philippe Ausoni, Amirreza Zobeiri

Experiments on vortex shedding from a blunt trailing edge symmetric hydrofoil operating at zero angle of attack in a uniform high speed flow, Re-h = 16.1 . 10(3) - 96.6 . 10(3), where the reference length h is the trailing edge thickness, are reported. The ...

2012

Parametric study of water column separation in Francis pump-turbine draft tube

François Avellan, Christophe Nicolet, Sébastien Alligné

The paper presents the modelling, simulation and analysis of the transient behaviour of a 340 MW pump-turbine in case of emergency shutdown in generation mode with particular attention to the possible draft tube water column separation. First, the model of ...

Soc Hydrotechnique France2012

How oblique trailing edge of a hydrofoil reduces the vortex-induced vibration

François Avellan, Mohamed Farhat, Philippe Ausoni, Amirreza Zobeiri

The effect of hydrofoil trailing edge shape on the wake dynamic and flow induced vibration is investigated at high Reynolds number, Re = 0.5 x 10(6)-2.9 x 10(6). Two NACA 0009 hydrofoils with blunt and oblique trailing edges are tested. The velocity field ...

Elsevier2012

Influence of the Pump-Turbine Guide Vanes Vibrations on the Pressure Fluctuations in the Rotor-Stator Vaneless Gap

François Avellan, Mohamed Farhat, Steven Roth, Vlad Hasmatuchi, Francisco Botero

We investigate the Rotor-Stator Interaction in a pump-turbine reduced scale model by considering fluid-structure coupling. The pressure fluctuations amplitude in the rotor-stator vaneless gap has generally been shown to increase linearly with the operating ...

2011

Numerical capture of wing tip vortex improved by mesh adaptation

François Avellan, Olivier Braun, Eric Joubarne

This paper presents a mesh adaptation procedure linked to a finite volume solver, the goal of which is to increase the precision of the numerical simulation of a wing tip vortex flow. The adaptation scheme is applied to hexahedron meshes and hybrid meshes ...

2011

Experimental Evidence of Rotating Stall in a Pump-Turbine at Off-Design Conditions in Generating Mode

François Avellan, Mohamed Farhat, Steven Roth, Vlad Hasmatuchi, Francisco Botero

An experimental investigation of the rotating stall in reduced scale model of a low specific speed radial pump-turbine at runaway and turbine brake conditions in generating mode is achieved. Measurements of wall pressure in the stator are performed along w ...

American Society of Mechanical Engineers2011

Mathematical modelling of swirling flow in hydraulic turbines for the full operating range

François Avellan

We introduce and validate a novel mathematical model for computing the radial profiles of both axial and circumferential velocity components, respectively, of the swirling flow exiting the runner of hydraulic turbines within the full operating range. We as ...

Elsevier2011

Non-Linear Stability Analysis of a Reduced Scale Model Pump-Turbine at Off-Design Operation

François Avellan, Andres Müller, Steven Roth, Christian Landry, Vlad Hasmatuchi, Sébastien Alligné

Nowadays, the pump-storage power plants are a proven solution for storing electricity at large scale and offering flexibility to the power management. Therefore, the hydraulic machines are increasingly subject to off-design operation, start-up and shutdown ...

2011

Hydrodynamics of a Pump-Turbine at Off-Design Operating Conditions: Numerical Simulation

François Avellan, Mohamed Farhat, Steven Roth, Vlad Hasmatuchi, Francisco Botero

Flow numerical simulations in a low specific speed radial pump-turbine scale model are performed to investigate off-design operating conditions in generating mode. The Best Efficiency Point (BEP) and the runaway operating conditions at 10° guide vanes open ...

2011

On the upper part load vortex rope in Francis turbine: Experimental investigation

François Avellan, Christophe Nicolet, Amirreza Zobeiri, Pierre Maruzewski

The swirling flow developing in Francis turbine draft tube under part load operation leads to pressure fluctuations usually in the range of 0.2 to 0.4 times the runner rotational frequency resulting from the so-called vortex breakdown. For low cavitation n ...

International Association For Hydraulic Research2010

Turbulence modeling for Francis turbine water passages simulation

François Avellan, Henri-Pascal Mombelli, Pierre Maruzewski

The applications of Computational Fluid Dynamics, CFD, to hydraulic machines life require the ability to handle turbulent flows and to take into account the effects of turbulence on the mean flow. Nowadays, Direct Numerical Simulation, DNS, is still not a ...

International Association For Hydraulic Research2010

Modal behavior of a reduced scale pump turbine impeller. Part II: Numerical simulation

François Avellan, Mohamed Farhat, Eduard Egusquiza, Xiaopeng Huang

A numerical simulation has been carried out to analyze the modal behavior of a reduced scale pump-turbine impeller. The simulation has been done using FEM method, in air and in water. The same boundary conditions than in the experiment were considered: fre ...

International Association For Hydraulic Research2010

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