On the physical mechanisms governing self-excited pressure surge in Francis turbines
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Hydraulic turbine runners, which operate under a wide range of heads and outputs, are subjected to considerable dynamic forces at off design conditions. Therefore a detailed knowledge of mean and fluctuating pressures is required for a safe design of the r ...
International Association For Hydraulic Research2000
Cavitation erosion of Francis turbines continues to impose costly repairs and loss of revenues. This erosion is primarily caused by leading edge cavitation. A revue of the literature reveals the non-existence of an absolutely validated detection technique ...
In this first part of a 2 papers series, we present the experimental procedure for onboard measurement of pressure and strain fluctuation in a model of low head Francis turbine. 28 miniature pressure sensors are fitted in the pressure and suction sides of ...
International Association For Hydraulic Research2002
The setting level of a hydraulic machine, specially for low head machines, is decided with respect to the possible alteration of the efficiency due to the cavity development. This alteration can easily be noticed by following the evolution of the efficienc ...
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 anal ...
International Association For Hydraulic Research1998
The setting level of an hydraulic machine, specially for low head machines, is decided with respect to the possible alteration of the efficiency due to the cavity development. This alteration can easily be noticed by plotting the evolution of the efficienc ...
Three dimensional numerical tools are now commonly used in the design or analysis process of the internai flow of hydraulic machinery. As an illustration of the use of such tools to study the internai flow of a Francis turbine, the computational results ob ...
International Association For Hydraulic Research1994
Stability of operation of Francis turbines Hydraulic disturbances often come with the operation of Francis turbines outside of design head and flow. In some cases, the excessive amplitude of the dynamic system response to these disturbances leads to res ...
The two techniques, vibratory monitoring and pit counting, show promising results for the prediction of prototype cavitation erosion from model tests of Francis turbines. These cavitation detection methods are compared in two set-ups at different power lev ...
International Association For Hydraulic Research1994
This paper presents similitude laws for steady-oscillatory phenomena associated with the off-design operation of Francis turbines. An appropriate procedure is proposed for stability of operation tests to be performed along with standard model tests. The el ...
International Association For Hydraulic Research1994