Andres Müller

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Related publications (26)

On the physical mechanisms governing self-excited pressure surge in Francis turbines

François Avellan, Andres Müller, Christian Landry, Arthur Tristan Favrel, Keita Yamamoto

The required operating range for hydraulic machines is continually extended in an effort to integrate renewable energy sources with unsteady power outputs into the existing electrical grid. The off-design operation however brings forth unfavorable flow pat ...

IOP science2014

Physical Mechanisms governing Self-Excited Pressure Oscillations in Francis Turbines

Andres Müller

The importance of renewable energy sources for the electrical power supply has grown rapidly in the past decades. Their often unpredictable nature however poses a threat to the stability of the existing electric grid. Hydroelectric powerplants play an impo ...

EPFL2014

Hydro-acoustic resonance behavior in presence of a precessing vortex rope: observation of a lock-in phenomenon at part load Francis turbine operation

François Avellan, Andres Müller, Christian Landry, Arthur Tristan Favrel, Keita Yamamoto

Francis turbines operating at part load condition experience the development of a cavitating helical vortex rope in the draft tube cone at the runner outlet. The precession movement of this vortex rope induces local convective pressure fluctuations and a s ...

IOP science2014

Interaction of a pulsating vortex rope with the local velocity field in a Francis turbine draft tube

François Avellan, Andres Müller, Steven Roth, Christian Landry, Matthieu Dreyer, Alberto Bullani, Arthur Tristan Favrel

Acoustic resonances in Francis turbines often define undesirable limitations to their operating ranges at high load. The knowledge of the mechanisms governing the onset and the sustenance of these instabilities in the swirling flow leaving the runner is es ...

IOP science2013

Modeling of Unsteady Friction and Viscoelastic Damping in Piping Systems

François Avellan, Christophe Nicolet, Andres Müller, Christian Landry

In real systems, the phenomena, such as pipe-wall viscoelasticity, unsteady friction or fluid structure interaction induce additional damping and dispersion of transient pressure waves than that defined by classical waterhammer. In this paper, unsteady fri ...

International Association For Hydraulic Research2012

Non-Linear Stability Analysis of a Reduced Scale Model Pump-Turbine at Off-Design Operation

François Avellan, Andres Müller, Steven Roth, Christian Landry, Vlad Hasmatuchi, Sébastien Alligné

Nowadays, the pump-storage power plants are a proven solution for storing electricity at large scale and offering flexibility to the power management. Therefore, the hydraulic machines are increasingly subject to off-design operation, start-up and shutdown ...

2011

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