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Christophe Nicolet

Cette personne a quitté l’EPFL

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Publications associées (48)

Page 1 sur 3

Methodology for Risk Assessment of Part Load Resonance in Francis Turbine Power Plant

François Avellan, Jean-Jacques Simond, Christophe Nicolet, Philippe Allenbach

At low flow rate operation, Francis turbines feature a cavitating vortex rope in the draft tube resulting from the swirling flow of the runner outlet. The unsteady pressure field related to the precession of the vortex rope induces plane wave propagating i ...

2006

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

François Avellan, Christophe Nicolet, Pierre Maruzewski, Amirreza Zobeiri

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

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

François Avellan, Christophe Nicolet, Christian Landry, Loïc Andolfatto, Joao Gomes Pereira Junior

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 ...

2018

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

Influence of the Hydraulic System Layout on the Stability of a Mixed Islanded Power Network

Silvio Giacomini, François Avellan, Christophe Nicolet, Christian Landry

Numerical simulation and stability analysis of an islanded power network comprising 40 MW of hydropower, 20 MW of wind power and 60 MW of gas-fired power plant are investigated. First, the modeling of each power plant is fully described. The wind farm is m ...

Springer Singapore2014

Turbine Speed Governor Parameters Validation in Islanded Production

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

The transient behavior of hydroelectric power plants is of high interest for ensuring stability of islanded electrical power networks. Therefore, it is suitable to determine and validate the set of parameters of a turbine speed governor using a realistic s ...

2007

Experimental investigation of the local wave speed in a draft tube with cavitation vortex rope

François Avellan, Christophe Nicolet, Arthur Tristan Favrel, Christian Landry, Andres Müller, Keita Yamamoto

Hydraulic machines operating in a wider range are subjected to cavitation developments inducing undesirable pressure pulsations which could lead to potential instability of the power plant. The occurrence of pulsating cavitation volumes in the runner and t ...

IOP Publishing Ltd2014

Experimental investigation of the local wave speed in a draft tube with cavitation vortex rope

François Avellan, Christophe Nicolet, Arthur Tristan Favrel, Christian Landry, Keita Yamamoto

IOP Publishing2014

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

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

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

International Association For Hydraulic Research2008

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

Hydraulic design of the diaphragm’s orifice at the entrance of the surge shaft of FMHL pumped-storage power plant

Giovanni De Cesare, Christophe Nicolet, Rafael Xavier Meriade Duarte, Fadi Hachem

The surge tank located at the upstream head of penstocks and shafts of hydropower plants is an effective measure to protect the headrace tunnels against high pressure fluctuations. It reflects the transient pressure waves that are generated by the variatio ...

TPU2013

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

Simulation tool linking hydroelectric production sites and electrical networks

François Avellan, Jean-Jacques Simond, Christophe Nicolet, Philippe Allenbach

Since many years the EPFL Laboratory of Electrical Machines develops SIMSEN, a numerical software package for the simulation of electrical power systems and adjustable speed drives, in transient and steady-state conditions, having an arbitrary topology. SI ...

2006

Modeling and Numerical Simulation of a Complete Hydroelectric Production Site

François Avellan, Jean-Jacques Simond, Christophe Nicolet, Philippe Allenbach

For many years the EPFL Laboratory for Electrical Machines develops SIMSEN, a numerical software package for the simulation in transient and steady-state conditions of electrical power systems and adjustable speed drives, having an arbitrary topology. SIMS ...

2007

On the prediction of the induced damage by the start-up sequence of Francis turbines: On operational resilience framework

Mario Paolone, Christophe Nicolet, Elena Vagnoni, Martin Seydoux

The number of transient operations in hydraulic machinery connected to power grid, notably start-ups and shut-downs, has observed a substantial increase in recent decades, primarily driven by the global shift toward intermittent renewable energy sources. S ...

Pergamon-Elsevier Science Ltd2024

Hydroacoustic modelling and numerical simulation of unsteady operation of hydroelectric systems

Christophe Nicolet

Hydropower represented in 1999 19% of the world electricity production and the absolute production is expected to grow considerably during the next 30 years. Francis turbines play a major role in the hydroelectric production due to their extended range of ...

EPFL2007

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