Cavitation erosion prediction on Francis turbines .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.