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François Avellan

Cette personne a quitté l’EPFL

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Publications associées (218)

Page 4 sur 11

Hydraulic performance evaluation of a micro-turbine with counter rotating runners by experimental investigation and numerical simulation

François Avellan, Elena Vagnoni, Loïc Andolfatto, Cécile Münch-Alligné

The development of energy recovery systems on existing water utility networks is a new challenge for increasing the sustainability of electricity generation mix. The concept of the new micro-turbine with counter rotating runners braces this goal by allowin ...

Pergamon-Elsevier Science Ltd2018

Variable speed operation of centrifugal pumps running as turbines. Experimental investigation

François Avellan, João Nuno Gomes Borga Delgado

Pumps running as turbines are pointed out as a cost-effective solution for energy recovery in pressurised water supply systems. However, these hydraulic machines feature low efﬁciency under variable discharge operation due to the lack of an inlet ﬂow contr ...

Pergamon-Elsevier Science Ltd2019

Unstable Operation of Francis Pump-Turbine at runaway: Rigid and Elastic Water Column Oscillation Modes

François Avellan, Jean-Jacques Simond, Basile Kawkabani, Sébastien Alligné

This paper presents a numerical simulation study of the transient behavior of a 2x340MW pump-turbine power plant, where the results show an unstable behavior at runaway. First, the modeling of hydraulic components based on equivalent schemes is presented. ...

2009

Comprehensive power loss modelling to improve the performance of an Energy Recovery Station for water utility networks

François Avellan, Cécile Münch-Alligné, Loïc Andolfatto, Daniel Biner

The work presented in this paper details the methodology applied to inventory and estimate the power losses in a micro-turbine with counter-rotating runners. The separation between the impact of design parameters and operational parameters on each identifi ...

Pennwell2017

Modal behavior of a reduced scale pump-turbine impeller. Part 1: Experiments

François Avellan, Mohamed Farhat

An experimental investigation has been carried out to quantify the effects of surrounding fluid on the modal behavior of a reduced scale pump-turbine impeller. The modal properties of the fluid-structure system have been obtained by Experimental Modal Anal ...

International Association For Hydraulic Research2010

Interaction of a rotating two-phase flow with the pressure and torque stability of a reversible pump-turbine operating in condenser mode

François Avellan, Elena Vagnoni, Loïc Andolfatto

The operation of a reversible pump-turbine in condenser mode requires to dewater the impeller by closing the guide vanes and injecting compressed air in the draft tube cone to reduce the friction torque on the impeller blades. A water discharge is injected ...

2019

Influence of the Francis turbine location under vortex rope excitation on the hydraulic system stability

François Avellan, Jean-Jacques Simond, Christophe Nicolet, Basile Kawkabani, Philippe Allenbach, Sébastien Alligné

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 ...

2009

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

Forced response analysis of hydroelectric systems

François Avellan, Pedro Camilo de Oliveira e Silva, Christophe Nicolet, Basile Kawkabani, Philippe Allenbach, Sébastien Alligné, Antoine Béguin

At off-design operating points, Francis turbines develop cavitation vortex rope in the draft tube which may interact with the hydraulic system. Risk resonance assessment by means of eigenmodes computation of the system is usually performed. However, the sy ...

International Association For Hydraulic Research2014

An original valveless artificial heart providing pulsatile flow tested in mock circulatory loops

François Avellan, Audrey Paulette Solange Maertens

Purpose: We present the test bench results of a valveless total artificial heart that is potentially compatible with the pediatric population. Methods: The RollingHeart is a valveless volumetric pump generating pulsatile flow. It consists of a single spher ...

Wichtig Editore2017

Simulation of pump-turbine prototype fast mode transition for grid stability support

François Avellan, Christophe Nicolet, Nicolas Ruchonnet, Antoine Béguin

The paper explores the additional services that Full Size Frequency Converter, FSFC, solution can provide for the case of an existing pumped storage power plant of 2x210 MW, for which conversion from fixed speed to variable speed is investigated with a foc ...

2017

Impact erosion prediction using the finite volume particle method with improved constitutive models

François Avellan, Ebrahim Jahanbakhsh, Audrey Paulette Solange Maertens, Sebastián Camilo Leguizamón Sarmiento, Siamak Alimirzazadeh, Christian Vessaz

Erosion damage in hydraulic turbines is a common problem caused by the high- velocity impact of small particles entrained in the fluid. In this investigation, the Finite Volume Particle Method is used to simulate the three-dimensional impact of rigid spher ...

IOP Publishing2016

Surface Parametrization of a Francis Runner Turbine for Optimum Design

François Avellan

The aim of this paper is to apply a surface parameterization to a blade. This geometric representation should be used as a practical tool in the process of design optimization. Most parameterizations are based on blade section approaches. The parameters ar ...

International Association For Hydraulic Research2004

Analysis of the Cavitating Draft Tube Vortex in a Francis Turbine Using Particle Image Velocimetry Measurements in Two-Phase Flow

François Avellan, Monica Iliescu

Partial flow rate operation of hydroturbines with constant pitch blades causes complex unstable cavitating flow in the diffuser cone. A particle image velocimetry (PIV) system allows investigating the flow velocity field in the case of a developing cavitat ...

2008

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

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

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

Upper part-load instability in a reduced-scale Francis turbine: an experimental study

François Avellan, Elena Vagnoni, Andres Müller, Ali Amini

Francis turbines with medium or high specific speeds may experience a particular type of instability in the upper part load in which the precessing vortex has an elliptical shape. The occurrence of the upper part-load instability (UPLI) is accompanied by l ...

SPRINGER2023

GPU-accelerated numerical analysis of jet interference in a six-jet Pelton turbine using Finite Volume Particle Method

François Avellan, Ebrahim Jahanbakhsh, Audrey Paulette Solange Maertens, Sebastián Camilo Leguizamón Sarmiento, Siamak Alimirzazadeh, Christian Vessaz

The Pelton turbine is an impulse turbine typically installed for high head hydroelectric power plants. For a site with a rated head H and discharge Q, a higher specific speed turbine results in a more compact generating unit with reduced manufacturing cost ...

Pergamon-Elsevier Science Ltd2020

Silt motion simulation using finite volume particle method

François Avellan, Ebrahim Jahanbakhsh, Christian Vessaz

In this paper, we present a 3-D FVPM which features rectangular top-hat kernels. With this method, interaction vectors are computed exactly and efficiently. We introduce a new method to enforce the no-slip boundary condition. With this boundary enforcement ...

IOP Publishing2014

Prediction of unstable full load conditions in a Francis turbine prototype

François Avellan, Elena Vagnoni, Joao Gomes Pereira Junior

Francis turbines operating in full load conditions feature an axisymmetric vortex rotating in the opposite direction of the turbine runner. In low-pressure conditions, the resulting cavitation vortex may enter in an unstable self-exciting process, leading ...

ACADEMIC PRESS LTD- ELSEVIER SCIENCE LTD2022

Transposition of the mechanical behavior from model to prototype of Francis turbines

François Avellan, Joao Gomes Pereira Junior

Hydropower is nowadays essential for balancing the electrical grid providing flexibility and fast response. The role of hydraulic turbines has changed from working at their Best Efficiency Point (BEP) to work in the whole operating range when demanded. Fra ...

Pergamon-Elsevier Science Ltd2020