Publications de Olivier Braun | EPFL Graph Search

Simulation of pump-turbine prototype fast mode transition for grid stability support

François Avellan, Christophe Nicolet, Nicolas Ruchonnet, Antoine Béguin, Olivier Braun

The paper explores the additional services that Full Size Frequency Converter, FSFC, solution can provide for the case of an existing pumped storage power plant of 2x210 MW, for which conversion from fixed speed to variable speed is investigated with a foc ...

2017

Efficient runner safety assessment during early design phase and root cause analysis

Olivier Braun

Fatigue related problems in Francis turbines, especially high head Francis turbines, have been published several times in the last years. During operation the runner is exposed to various steady and unsteady hydraulic loads. Therefore the analysis of force ...

International Association For Hydraulic Research2012

Numerical capture of wing tip vortex improved by mesh adaptation

François Avellan, Olivier Braun, Eric Joubarne

This paper presents a mesh adaptation procedure linked to a finite volume solver, the goal of which is to increase the precision of the numerical simulation of a wing tip vortex flow. The adaptation scheme is applied to hexahedron meshes and hybrid meshes ...

2011

Fluid-structure coupling for an oscillating hydrofoil

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

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

Part load flow in radial centrifugal pumps

Olivier Braun

Centrifugal pumps are required to sustain a stable operation of the system they support under all operating conditions. Minor modifications of the surfaces defining the pump's water passage can influence the tendency to unstable system operation significan ...

EPFL2009

Hydro Elastic Behavior of Vibrating Blades

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

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

Numerical investigations of fluid structure coupling: oscillating hydrofoil

François Avellan, Olivier Braun, Cécile Münch-Alligné

This paper presents an investigation of the hydro elastic behavior of vibrating blades in hydraulic machines, which is of strong interest for turbo machinery applications. As a representative case study for vibrating blade in hydraulic machines, a NACA 000 ...

2008

Unsteady Numerical Simulations of the Flow Related to the Unstable Energy-Discharge Characteristic of a Medium Specific Speed Double Suction Pump

François Avellan, Philippe Dupont, Olivier Braun

Regions of positive slope in the pressure-discharge characteristics can result in a reduction or even lack of damping of system instabilities. They are therefore one of the major concerns in design and operation of centrifugal pumps as they are limiting th ...

2007

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

Einfluss der Gefügeheterogenität auf das Bruchverhalten von Schweissverbindungen

Olivier Braun

EPFL1985