Paul Bourdon

Cavitation Erosion Prediction on Francis Turbines Part 1 : Measurements on the Prototype

In the process of developing tools for cavitation erosion prediction of prototypes from model tests, 4 on board aggressiveness evaluation methods were tested on a severely eroded blade of a 266 MW Francis turbine. These are pressure, pit counting, DECER electrochemical and vibration measurements. All methods provided coherent results on the blade mounted measurements. The test program provided understanding of the heterogeneous erosion distribution of the prototype blades and quantitative data for comparison in subsequent tests on the model of the machine.

Cavitation Erosion Prediction on Francis Turbines-Part 3 Methodologies of Prediction

In the frame of a joint research programme between EDF, Hydro-Quebec and IMHEF, different methods are investigated to predict cavitation erosion on Francis turbines from model. They are based on measurement of pitting, pressure fluctuations and acceleration. The measurement techniques have been detailed in Part 1 and Part 2. The present article describes essentially the theoretical and practical aspects of the methods and discusses the results obtained until now from the model and prototype tests. The first analysis shows that the methods proposed are suitable to measure cavitation aggressiveness on model and on prototype, and that the level on the model is several orders of magnitude smaller than on the prototype. To adjust transposition laws, a more complete set of data is needed.

Cavitation Erosion Prediction on Francis Turbines. Part 2 Model Tests and Flow Analysis

Different measurement techniques have been used to detect cavitation on a Francis turbine model. The results are compared to those obtained on the prototype and presented in the first of this series of articles. The runner model used for that study is build on the basis of a geometrical recovery of one of most eroded blade of the prototype. The results of the different measurements are presented and commented by comparison with prototype measurements. This comparison leads to a proposal of the physics which should be involved in transposition laws for the prediction of prototype erosion from cavitation model tests. The consequences of such scaling laws, as well as their application to the prototype and model results, are part of the third facet of this work.

Hydro Turbine Profitability and Cavitation Erosion

Yearly cavitation erosion inspections on a turbine can easily cost 5K

The Hydrodynamic Aggressiveness of Cavitating Flows in Hydro Turbines

in manpower and up to 50

Some Hydro Quebec Experiences on the Vibratory Approach for Cavitation Monitoring

per MWhour of production in lost revenue during machine downtime. Cavitation repairs can last from 2 to 4 weeks with manpower, equipment and material repair costs from 15 to over lOOK

Erosion vibratory fingerprint of leading edge cavitation of a NACA profile and of a Francis model and prototype hydroturbine

depending on machine size and accumulated erosion. Production losses are much more expensive for these long outages. These expenses can now be minimized with the knowledge of the erosion risk associated with operating conditions. The application of the Hydro-QuCbec vibratory cavitation detection method allows identifying the potential profitability gains that become important in some machine designs. Four case examples illustrate this point.