Publications de Loïc Andolfatto

Oxygen diffusion through air–water free surfaces in a pump–turbine operating in condenser mode

François Avellan, Elena Vagnoni, Loïc Andolfatto, Pierre Leroy

The present research aims at understanding the mass transfer of air into water in a reversible pump turbine operating in condenser mode. In particular, the diffusion of oxygen through the water free-surface both in the vaneless gap between the impeller bla ...

2019

Hill chart modelling using the Hermite polynomial chaos expansion for the performance prediction of pumps running as turbines

François Avellan, Loïc Andolfatto, João Nuno Gomes Borga Delgado

Pumps running as turbines are suitable hydraulic machines for micro hydropower applications. The selection of the proper pumps to install in a given site still remains a major challenge, as pump manufacturers do not provide the characteristic curves data i ...

Elsevier2019

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

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

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

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

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

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

Experimental investigation of the sloshing motion of the water free surface in the draft tube of a Francis turbine operating in synchronous condenser mode

François Avellan, Arthur Tristan Favrel, Elena Vagnoni, Loïc Andolfatto

Hydropower units may be required to operate in condenser mode to supply reactive power. In this operating mode, the water level in the turbine or pump-turbine is decreased below the runner by closing the guide vanes and injecting pressurized air. While ope ...

2018

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

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

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

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, Pierre Leroy

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

Rotating air-water ring in the vaneless gap of a pump-turbine operating in condenser mode

François Avellan, Elena Vagnoni, Loïc Andolfatto, Pierre Leroy

The rotating air-water ring, featuring a bubbly flow, in the vaneless gap of a reduced scale physical model of a pump-turbine operating in dewatered condition is investigated. High speed visualizations are performed together with pressure fluctuation measu ...

2018

Monitoring a Francis Turbine Operating Conditions

François Avellan, Joao Gomes Pereira Junior, Loïc Andolfatto

Francis turbines are designed for a specific set of operating conditions that is particular to each hydropower plant site. It allows this type of turbine to extract as much hydraulic power as possible, as long as they are operating in the right conditions. ...

2018

Air-Water Ring in the Vaneless Gap of a Reversible Pump-Turbine Operating in Condenser Mode

François Avellan, Elena Vagnoni, Loïc Andolfatto, Pierre Leroy

2018

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

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

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

Model testing beyond the scope of International Standards: an outlook

François Avellan, Loïc Andolfatto

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 ...

2018

Use of compact Laser Doppler Velocimetry in reduced scale model testing of hydraulic machines

François Avellan, Andres Müller, Vincent Berruex, Loïc Andolfatto, Masashi Sakamoto

Laser based flow survey methods such as Laser Doppler Velocimetry (LDV) or Particle Image Velocimetry (PIV) have long been used for studying the flow in hydraulic machines. Even if the results have crucially improved our understanding of potentially destab ...

2018

Toward design optimization of a Pelton turbine runner

François Avellan, Christian Vessaz, Christophe Tournier, Loïc Andolfatto

The objective of the present paper is to propose a strategy to optimize the performance of a Pelton runner based on a parametric model of the bucket geometry, massive particle based numerical simulations and advanced optimization strategies to reduce the d ...

Springer Verlag2017

On the sloshing free surface in the draft tube cone of a Francis turbine operating in synchronous condenser mode

François Avellan, Elena Vagnoni, Loïc Andolfatto

Hydropower plants may be required to operate in synchronous condenser mode in order to supply reactive power to the grid for compensating the fluctuations introduced by the intermittent renewable energies such wind and solar. When operating in this mode, t ...

2017

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

Engineering & Performance of DuoTurbo: Microturbine with Counter-Rotating Runners

François Avellan, Vlad Hasmatuchi, Loïc Andolfatto, Daniel Biner

Considering the nuclear phase-out strategy of several European countries and the future tendency to promote renewable energies, the exploitation of small hydropower sites (

International Association For Hydraulic Research2016

Evaluation of the shape deviation of non rigid parts from optical measurements

Loïc Andolfatto

This paper deals with an approach to identify geometrical deviations of flexible parts from optical measurements. Each step of the approach defines a specific issue which we try to respond to. The problem of measurement uncertainties is solved using an ori ...

Springer Verlag2017

Simulation of energy recovery on water utility networks by a micro-turbine with counter-rotating runners

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

Wherever relief valves and other energy dissipation devices are installed to limit the pressure, water utility networks provide unexploited hydropower potentials. This is mainly due to a lack of economically viable technologies for energy recovery in the p ...

International Association For Hydraulic Research2016

Automated hill chart modeling procedure to estimate the performance of double regulated units

François Avellan, Henri-Pascal Mombelli, Loïc Andolfatto

The work presented in this paper details an original procedure developed in order to automatically build on-cam surfaces for double-regulated hydropower units such as Kaplan or bulb turbines. The proposed method allows a sparse exploration of the operating ...

2016