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François Avellan

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Publications associées (218)

Hydroacoustic Modeling of Rotor Stator Interaction in Francis Pump-Turbine

François Avellan, Christophe Nicolet, Nicolas Ruchonnet

A one-dimensional hydroacoustic model is set up to perform the numerical simulation of the rotor-stator interaction of a Francis pump-turbine scaled model. The numerical results enable to identify both rotating diametrical modes in the vaneless gap between ...

2006

Simulation tool linking hydroelectric production sites and electrical networks

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

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

Cavitation in Kármán Vortices and Flow Induced Vibrations

François Avellan, Mohamed Farhat, Philippe Ausoni

The shedding process of the Kármán vortices at the trailing edge of a 2D hydrofoil at high Reynolds numbers is investigated. The focus is put on the effect of the cavitation on the vortex street morphology. A direct insight is also provided on the role of ...

2006

Onboard Flow Visualization in a Pelton Turbine Bucket

Alexandre Perrig, François Avellan

Flow visualizations using endoscopes in a 21-bucket single-injector reduced scale Pelton turbine are performed for 2 operating points. 2 types of visualizations are performed with a CMOS high-speed camera: (i) an onboard visualization of the flow in the bu ...

International Association For Hydraulic Research2006

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

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

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

Analysis of the Swirling Flow Downstream a Francis Turbine Runner

François Avellan

An experimental and theoretical investigation of the flow at the outlet of a Francis turbine runner is carried out in order to elucidate the causes of a sudden drop in the draft tube pressure recovery coefficient at a discharge near the best efficiency ope ...

2006

One-Dimensional Modeling of Rotor Stator Interaction in Francis Pump-Turbine

François Avellan, Christophe Nicolet, Nicolas Ruchonnet

2006

Cavitation effects on fluid-structure interaction in the case of a 2D hydrofoil

François Avellan, Mohamed Farhat, Philippe Ausoni

In the present study, we have carried out an experimental investigation on the fluid-structure interaction caused by Karman vortices in the wake of a truncated 2D hydrofoil. The instrumentation involves a high frequency accelerometer and high speed visuali ...

2005

Numerical Analysis of Flow Phenomena Related to the Unstable Energy-Discharge Characteristic of a Pump-Turbine in Pump Mode

François Avellan, Olivier Braun

Regions of positive slope in the pressure-discharge characteristics are one of the major concerns in design and operation of centrifugal pumps, as they are limiting the admissible operating range to values above the critical discharge. The industrial pump ...

2005

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

Wall Friction and Boundary Layer Development in the Cone of a Francis Turbine Scale Model

François Avellan, Elena Berca

To characterize the boundary layer development, in the cone of the Francis turbine, wall friction and velocity measurements are performed. The mean wall friction measurements evidence the increasing risk of the boundary layer separation at the cone wall wi ...

International Association For Hydraulic Research2004

Numerical Flow Analysis in a Pelton Turbine Bucket

Alexandre Perrig, François Avellan, Mohamed Farhat

The flow in the Pelton turbine bucket is three-dimensional, unsteady, turbulent, features a free surface, and is influenced by the rotation-induced forces. It is therefore difficult to investigate how the energy transfer takes place between the water flow ...

International Association For Hydraulic Research2004

Flow Simulation in an Elbow Diffuser : Verification and Validation

François Avellan, Sebastiano Mauri

Numerical simulation of the unsteady turbulent flow in a three-dimensional draft tube geometry is performed. The investigation is carried out with a commercial finite volume solver implementing the Reynolds averaged Navier-Stokes equations. The modeling of ...

International Association For Hydraulic Research2002

Unsteady Rotor - Stator Analysis of Hydraulic Pump - Turbine : CFD and Experimental Approach

François Avellan

The parallel rotor-stator computation capabilities of Fine Turbo and CFX-TASCflow CFD commercial codes have been investigated within the frame of the European ESPRIT project HPNURSA. Unsteady computations have been performed for simple test cases, where fl ...

International Association For Hydraulic Research2002

Experimental and Numerical Analysis or Free Surface Flows in a Rotating Bucket

Sonia Kvicinsky, François Avellan

The aim of this study was to provide a complete experimental and numerical analysis of the flow in a rotating Pelton bucket. For the experimental analysis, several functioning points have been used in order to study differences which may occur in various s ...

International Association For Hydraulic Research2002

A New tool for the simulation of dynamic behaviour of hydroelectric power plants

François Avellan, Alain Sapin, Jean-Jacques Simond

An analytical approach allowing modelling transient phenomena in pipes, valves, surge tank and Francis turbines based on impedance method is developed. These models are introduced in a software called “SIMSEN”, which simulates the behaviour of complex appl ...

2001

Experimental investigation on forces due to vortex cavitation collapse for different materials

François Avellan, Philippe Dupont

1999

Centrifugal Pump Performance Drop due to leading Edge Cavitation : Numerical Predictions compared with Model Tests

François Avellan, Philippe Dupont

1998

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