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Mohamed Farhat

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Publications associées (118)

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

François Avellan, Mohamed Farhat, Steven Roth, Vlad Hasmatuchi, Francisco Botero

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. ...

International Association For Hydraulic Research2010

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

François Avellan, Mohamed Farhat, Philippe Ausoni, Amirreza Zobeiri

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 ...

American Soc Mechanical Engineers2010

Luminescence from hydrodynamic cavitation

Mohamed Farhat

The majority of the research on cavitation luminescence has focused on the sonoluminescence or chemiluminescence generated by cavitation induced through ultrasound, with a lesser body of work on the luminescence induced by laser- or spark induced cavitatio ...

2010

Fluid-structure coupling for an oscillating hydrofoil

François Avellan, Mohamed Farhat, Philippe Ausoni, Olivier Braun, Cécile Münch-Alligné

Fluid-structure investigations in hydraulic machines using coupled simulations are particularly time-consuming. In this study, an alternative method is presented that linearizes the hydrodynamic load of a rigid, oscillating hydrofoil. The hydrofoil, which ...

Elsevier2010

High-speed flow visualization in a pump-turbine under off-design operating conditions

François Avellan, Mohamed Farhat, Steven Roth, Vlad Hasmatuchi, Francisco Botero

The flow hydrodynamics in a low specific speed radial pump-turbine reduced scale model is experimentally investigated under off-design operating conditions in generating mode. Wall pressure measurements, in the stator, synchronized with high-speed flow vis ...

International Association For Hydraulic Research2010

Modal behavior of a reduced scale pump-turbine impeller. Part 1: Experiments

François Avellan, Mohamed Farhat, Eduard Egusquiza

An experimental investigation has been carried out to quantify the effects of surrounding fluid on the modal behavior of a reduced scale pump-turbine impeller. The modal properties of the fluid-structure system have been obtained by Experimental Modal Anal ...

International Association For Hydraulic Research2010

Advanced Instrumentation for Measuring Fluid-Structure Coupling Phenomena in the Guide Vanes Cascade of a Pump-Turbine Scale Model

François Avellan, Mohamed Farhat, Steven Roth, Vlad Hasmatuchi, Francisco Botero

In the present study, the fluid-structure coupling is investigated in the guide vanes of a pump-turbine scale model placed in one of the test rigs of the Laboratory for Hydraulic Machines (EPFL) in Lausanne. The paper focuses on the advanced instrumentatio ...

American Soc Mechanical Engineers, Three Park Avenue, New York, Ny 10016-5990 Usa2010

Determination of a scale-up factor from mixing time studies in orbitally shaken bioreactors

Christos Comninellis, Florian Maria Wurm, Mohamed Farhat, David Hacker, Stéphanie Tissot

Efficient mixing in bioreactors is essential in order to avoid concentration gradients which can be harmful for mammalian cells. To study mixing and its scalability in orbitally shaken cylindrical bioreactors, we measured mixing times in containers with no ...

Elsevier2010

Effect of Flow Diverter Porosity on Intra-aneurysmal Blood Flow

Mohamed Farhat

Background and Purpose: Growth and rupture, the two events that dominate the evolution of an intracranial aneurysm, are both dependent on intraaneurysmal flow. Decrease of intraaneurysmal flow is considered an attractive alternative for treating intracrani ...

2009

Vortex shedding from blunt and oblique trailing edge hydrofoils

François Avellan, Mohamed Farhat, Philippe Ausoni, Amirreza Zobeiri

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 ...

Brno university of technology2009

Experimental investigation of a pump-turbine at off-design operating conditions

François Avellan, Mohamed Farhat, Pierre Maruzewski, Vlad Hasmatuchi

Pumped storage power plants are key components for the development of new renewable CO2-free primary energies and the security enhancement of electricity supply. They also offer interesting business opportunities in nowadays liberalized electricity market. ...

Brno University of Technology2009

Techniques for generating centimetric drops in microgravity and application to cavitation studies

Mohamed Farhat, Danail Obreschkow, Nicolas Dorsaz, Philipp Kobel, Aurèle De Bosset

This paper describes the techniques and physical parameters used to produce stable centimetric water drops in microgravity, and to study single cavitation bubbles inside such drops (Parabolic Flight Campaigns, European Space Agency ESA). While the main sci ...

2009

Hydrodynamic Damping Identification from an Impulse Response of a Vibrating Blade

François Avellan, Mohamed Farhat, Steven Roth, Cécile Münch-Alligné, Martin Calmon

In the present study, the identification of hydrodynamic damping is investigated in the case of 2D blade placed in the test section of the EPFL High Speed Cavitation Tunnel. A non intrusive technique, based on a spark generated bubble, is used to generate ...

Brno University of Technology2009

Experimental Investigation of Flow Instabilities and Rotating Stall in a High-Energy Centrifugal Pump Stage

François Avellan, Philippe Dupont, Maher Kayal, Mohamed Farhat, Laurent Fabre, Stefan Berten

In centrifugal pumps, the interaction between the rotating impeller and the stationary diffuser generates specific pressure fluctuation patterns. When the pump is operated at off design conditions, these pressure fluctuations increase. The resulting rise o ...

ASME2009

Methodologies to assess blood flow in cerebral aneurysms: Current state of research and perspectives

Nikolaos Stergiopoulos, Luca Augsburger, Mohamed Farhat, Philippe Reymond, Edouard Fonck

With intracranial aneurysms disease bringing a weakened arterial wall segment to initiate, grow and potentially rupture an aneurysm, current understanding of vessel wall biology perceives the disease to follow the path of a dynamic evolution and increasing ...

2009

One-Dimensional Analysis of Full Load Draft Tube Surge

François Avellan, Christophe Nicolet, Mohamed Farhat

One-dimensional stability analysis of a hydraulic system composed of a penstock, a runner, and a draft tube was carried out to determine the cause of the full load draft tube surge. It is assumed that the cavity volume at the runner exit is a function of t ...

2008

Hydro Elastic Behavior of Vibrating Blades

François Avellan, Mohamed Farhat, Philippe Ausoni, Olivier Braun, Cécile Münch-Alligné

Fluid-structure investigations in hydraulic machines using coupled simulations are extremely time-consuming; therefore we develop an alternative method. In this paper, a model is proposed to predict fluid-structure coupling by linearizing the hydrodynamic ...

International Association For Hydraulic Research2008

Cavitation Bubbles inside Spherical Water Drops in Microgravity

Mohamed Farhat

We studied spark-generated bubble inside stable water drops produced in microgravity. The closed and isolated liquid geometry results in a unique confinement of subsequent shockwaves, since the latter bounce of the free surface. This setting results in an ...

Warwick University, UK2008

One-dimensional analysis of full load draft tube surge

François Avellan, Christophe Nicolet, Mohamed Farhat

A previous report by the present authors [1] clarified the diffuser effect of the draft tube and the effects of swirl in the runner downstream on the hydraulic instabilities in power generation plants. The present study was intended to study the effect of ...

International Association For Hydraulic Research2008

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

François Avellan, Mohamed Farhat, Philippe Ausoni

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 ...

2007

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