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Sébastien Alligné

Cette personne a quitté l’EPFL

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Publications associées (26)

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Forced and Self Oscillations of Hydraulic Systems Induced by Cavitation Vortex Rope of Francis Turbines

Sébastien Alligné

With economical energy market strategies based on instantaneous pricings of electricity as function of the demand or the predictions, operators harness more hydroelectric facilities to off-design operating points to cover the variations of the electricity ...

EPFL2011

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

François Avellan, Christophe Nicolet, Sébastien Alligné, Nicolas Ruchonnet

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 ...

International Association For Hydraulic Research2010

Influence of the vortex rope location of a Francis Turbine 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 ...

International Association For Hydraulic Research2008

Cavitation influence on hydroacoustic resonance in pipe

François Avellan, Christophe Nicolet, Sébastien Alligné, Nicolas Ruchonnet

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

Procedure for predicting part load resonance in Francis turbine hydropower units based on swirl number and local cavitation coefficient similitude

François Avellan, Christophe Nicolet, Sébastien Alligné, Christian Landry, Loïc Andolfatto, Arthur Tristan Favrel

Francis turbines operating at part load conditions develop a cavitation precessing vortex known as a vortex rope in the draft tube cone below the runner outlet. At part load conditions, this vortex precession acts as an excitation source inducing pressure ...

ACADEMIC PRESS LTD- ELSEVIER SCIENCE LTD2019

Prediction of Francis Turbine Prototype Part Load Pressure and Output Power Fluctuations with Hydroelectric Model

François Avellan, Christophe Nicolet, Christian Landry, Sébastien Alligné, Joao Gomes Pereira Junior, Antoine Béguin

The prediction of pressure and output power fluctuations amplitudes on Francis turbine prototype is a challenge for hydro-equipment industry since it is subjected to guarantees to ensure smooth and reliable operation of the hydro units. The European FP7 re ...

2017

Experimental investigation of the mass flow gain factor in a draft tube with cavitation vortex rope

François Avellan, Arthur Tristan Favrel, Christian Landry, Andres Müller, Sébastien Alligné, Keita Yamamoto

At off-design operating operations, cavitating flow is often observed in hydraulic machines. The presence of a cavitation vortex rope may induce draft tube surge and electrical power swings at part load and full load operations. The stability analysis of t ...

2017

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

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

Numerical Simulation of Nonlinear Self Oscillations of a Full Load Vortex Rope

François Avellan, Christophe Nicolet, Pierre Maruzewski, Vlad Hasmatuchi, Sébastien Alligné, Nicolas Ruchonnet

Self excited instabilities or oscillations of a cavitating full load vortex rope occur due to an interaction between the gas volume and the acoustic waves. From the onset of the oscillations, the amplitudes grow until they reach a maximum, called the “limi ...

2009

RANS computations for identification of 1-D cavitation model parameters: application to full load cavitation vortex rope

François Avellan, Christophe Nicolet, Andres Müller, Sébastien Alligné

Due to the massive penetration of alternative renewable energies, hydropower is a key energy conversion technology for stabilizing the electrical power network by using hydraulic machines at off design operating conditions. At full load, the axisymmetric c ...

International Association For Hydraulic Research2016

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

Measurement of the Self-Oscillating Vortex Rope Dynamics for Hydroacoustic Stability Analysis

François Avellan, Sébastien Alligné, Keita Yamamoto

Flow instabilities in hydraulic machines often feature oscillating cavitation volumes, which locally introduce compliance and mass flow gain effects. These unsteady characteristics play a crucial role in one-dimensional stability models and can be determin ...

American Society of Mechanical Engineers2016

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

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

Reduced scale model testing for prediction of eigenfrequencies and hydro-acoustic resonances in hydropower plants operating in off-design conditions

François Avellan, Christophe Nicolet, Christian Landry, Sébastien Alligné, Arthur Tristan Favrel, Joao Gomes Pereira Junior

The massive penetration of the electrical network by renewable energy sources, such as wind and solar, pushes the operators to extend hydropower plant units operating range to meet the transmission system operator requirements. However, in off-design opera ...

2019

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

A fully modular tool for small-signal stability analysis of hydroelectric systems

Pedro Camilo de Oliveira e Silva, Basile Kawkabani, Philippe Allenbach, Sébastien Alligné

In electrical systems, the small-signal stability analysis method is usually applied to synchronous machines by using the Park representation (d, q-components). This paper presents the generalization of a different approach for this method, based on a, b, ...

IEEE2014

Hydroelectric System Response to Part Load Vortex Rope Excitation

François Avellan, Christophe Nicolet, Christian Landry, Sébastien Alligné, Joao Gomes Pereira Junior, Antoine Béguin

International Association For Hydraulic Research2016

RANS computations for identification of 1-D cavitation model parameters: application to full load cavitation vortex rope

François Avellan, Christophe Nicolet, Andres Müller, Sébastien Alligné

2017

Prediction of hydro-acoustic resonances in hydropower plants by a new approach based on the concept of swirl number

François Avellan, Christophe Nicolet, Arthur Tristan Favrel, Christian Landry, Sébastien Alligné, Loïc Andolfatto, Joao Gomes Pereira Junior

Hydropower plant units operating in off-design conditions are subject to cavitation flow instabilities, potentially inducing hydro-acoustic resonances under certain conditions. They can be predicted by using one-dimensional numerical models of hydropower p ...

Taylor & Francis Ltd2019