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 important role in regulating the integration of renewable energy sources into the network by supplying on-demand load balancing as well as primary and secondary power network control. Therefore, the operating ranges of hydraulic machines has to be continuously extended, which potentially produces undesirable flow phenomena involving cavitation. An example is the formation of a gaseous volume in the swirling flow leaving a Francis turbine runner at off-design operating conditions. At high load, this so called vortex rope is shaped axisymmetrically and may enter a self-excited oscillation, measurable through significant fluctuations of the pressure throughout the system and the mechanical torque transferred to the generator. The main research activities include the identification of the physical mechanisms governing this self-sustained, unstable behavior by measurement. Furthermore, the key parameters of numerical approaches using one-dimensional hydroacoustic flow models or CFD require experimental validation. For this purpose, a comprehensive data base of various flow and system parameters at varying operating conditions has to be provided.
* Born in Sarnen, canton of Obwalden, Switzerland.
* BSc studies in mechanical engineering at EPFL in Lausanne, Switzerland.
* MSc studies in mechanical and aeronautical engineering at KTH in Stockholm, Sweden.
* 2008: Master thesis at the Industrial Energy Systems Laboratory (LENI) at EPFL with Prof. D. Favrat.
* 2008-2010: Work as a development and test engineer at ABB Switzerland Ltd, Electrical Machines.
* 2010-2014: Doctoral assistant at the EPFL laboratory for hydraulic machines (LMH) with Prof. F. Avellan.
* 2013: Visiting research fellow at Osaka University, Toyonaka, Japan, with Prof. Y. Tsujimoto.
* 2014: PhD thesis "Physical mechanisms governing self-excited pressure oscillations in Francis turbines".