Publications by François Avellan

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The current work intends to improve the cavitation erosion prediction methodology in hydro turbines by the use of onboard vibration measurements taken on the rotating shaft. For that, a measuring campaign in two similar Francis turbine prototypes has been carried out. In particular, one machine is a well known case of severe erosion on all the blades meanwhile the second machine does not present any erosion at all. A miniature telemetry system has been mounted on the shaft in both cases to transmit the sign

Extending the operating range of modern pump-turbines becomes increasingly important in the course of the integration of renewable energy sources in the existing power grid. However, at partial load condition in pumping mode, the occurrence of rotating sta ...

The sustainability of the electricity mix can be increased by introducing recovery energy systems on existing water supply infrastructures. The concept of the new counter rotating micro-turbine presented in this work is a competitive option for energy reco ...

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 ...

The dynamics of the rotating vortex taking place in the discharge ring of a Francis turbine for partial flow rate operating conditions and cavitation free conditions is studied by carrying out both experimental flow survey and numerical simulations. 2D las ...

Flow numerical simulations in a low specific speed radial pump-turbine scale model are performed to investigate off-design operating conditions in generating mode. The Best Efficiency Point (BEP) and the runaway operating conditions at 10° guide vanes open ...

At a deep part load operation, Francis turbines are subject to the formation of inter-blade cavitation vortices inside blade channels, however its characteristics are not fully understood yet. The present study aims to investigate the development of the in ...

The influence of the cavitation level on the vortex shedding frequency is used to compare the flow field in the wake of a blunt hydrofoil, with and without hydroelastic lock-in, and with a constant Reynolds number. Accurate LOA measurements allow us to examine in detail the base flow regime considered as the excitation source of the hydroelastic phenomena. Thanks to these measurements, a second vortex street superposed on the Karman street has been observed. Comparisons between measurements and calculations

The present study deals with the shedding process of the Kármán vortices in the wake of a NACA0009 hydrofoil at high Reynolds number. This research addresses the effects of the foil leading edge roughness on the wake dynamic with a special focus on the vor ...

Existing water utility networks provides a wide, distributed and unexploited hydropower potential. The installation of energy recovery stations on existing infrastructures limits both the required investment and the environmental impact. The counter-rotati ...

The present study concerns fluid-structure coupling phenomena occurring in a guide vane cascade of a pump-turbine scale model placed in the EPFL PF3 test rig. An advanced instrument set is used to monitor both vibrating structures and the surrounding flow. ...

The phenomenon of vortex shedding behind a hydrofoil is an important issue from both scientific and technical point of view. The resulting fluctuating forces may lead to excessive vibrations and premature cracks in the hydraulic machines. According to prev ...

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 ...

The objective of the present paper is to perform an accurate numerical simulation of the high-speed water jet impinging on a Pelton bucket. To reach this goal, the Finite Volume Particle Method (FVPM) is used to discretize the governing equations. FVPM is ...

The shedding process of the von Kármán vortices is shown to be highly related to the state of the boundary layer over the entire hydrofoil: The selected hydrofoil has a laminar-turbulent boundary layer transition at mid-chord for an incidence angle of 0° a ...

The aim of the paper is to present the results of investigations conducted on the free surface flow in a Pelton turbine model bucket. Unsteady numerical simulations, based on the two-phase homogeneous model, are performed together with wall pressure measur ...

This paper presents an experimental investigation of the vortex shedding in the wake of blunt and oblique trailing edge hydrofoils at high Reynolds number, Re=5 10 5 - 2.9 10 6. The velocity field in the wake is surveyed with the help of Particle-Image-Vel ...

The prediction of pressure 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 research project Hy ...

Hydraulic machine design can now take advantage of advanced flow calculation methods which are made available by several CFD software companies. Thanks to these recent developments, the so called "Volume Of Fluid" (VOF) methods can be now used for the analysis of the free surface flows in a Pelton Turbine. The aim of this paper is to evaluate this VOF approach with respect to the computation of the jet at the outlet of a Pelton injector and its trajectory in the buckets.

Pressure pulsation phenomena in a large Kaplan turbine are investigated by means of numerical simulations (CFD) and prototype measurements in order to study the dynamic behavior of flow due to the blade passage and its interaction with other components of ...

François Avellan

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Cavitation Erosion Prediction in Hydro Turbines from Onboard Vibrations

High-resolution LES of the rotating stall in a reduced scale model pump-turbine

Application of Laser Doppler Velocimetry to the development of a counter rotating micro-turbine

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

Experimental Study and Numerical Simulation of the Flindt Draft Tube Rotating Vortex

Hydrodynamics of a Pump-Turbine at Off-Design Operating Conditions: Numerical Simulation

Flow characteristics and influence associated with inter-blade cavitation vortices at deep part load operations of a Francis turbine

Wake flow analysis for a hydrofoil with and without hydroelastic lock-in

Cavitation in Kármán Vortex Shedding from 2D Hydrofoil: Wall Roughness effects

Analytical hill chart towards the maximisation of energy recovery on water utility networks with counter rotating micro-turbine

Fluid-Structure Coupling in the Guide Vanes Cascade of a Pump-Turbine Scale Model

Vortex shedding from blunt and oblique trailing edge hydrofoils

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

Flow simulation of a Pelton bucket using finite volume particle method

Hydrofoil Roughness Effects on von Kármán Vortex Shedding

Flow in a Pelton Turbine Bucket: Numerical and Experimental Investigations

Experimental investigation of the vortex shedding dynamic in the wake of oblique and blunt trailing edge hydrofoils using PIV-POD method

Francis turbine draft tube modelling for prediction of pressure fluctuations on prototype

Flow Calculations in Pelton Turbines,- Part 2 : Free Surface Flows

Pressure pulsation in Kaplan turbines: Prototype-CFD comparison