CAVITATION EROSION PREDICTION ON FRANCIS TURBINES-PART 1 MEASUREMENTSONTHEPROTOTYPE 1. Abstract P. BOURDON, M.FARHAT, R. SIMONEAU Hydro-Québec 1800 bout. Lionel Boulet, Varennes, Québec, Canada, J3X lSl F. PEREIRA, P. DUPONT., F. AVELLAN IMHEF/EPFL 33 av. de Cour, CH 1007 Lausanne, Switzerland J.-M. DOREY Electricité de France 6, Quai Watier, 78401 CHATOU Cédex, France In the process of developing tools for cavitation erosion prediction of prototypes from mode) 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 mode) of the machine. 2. Introduction The prediction of cavitation erosion of a prototype turbine from mode! tests requires that measurement tools be available to characterize the aggressiveness of the cavitating flow in both scales. To develop such tools, IMHEF, Electricité de France and Hydro-Québec pooled their resources in an ambitious research program involving various measurement techniques bath on the prototype and on the mode) of a 266 MW Francis turbine with a well documented cavitation erosion history. Preliminary measurements on this prototype (1) had proven to be incomplete but also very encouraging. A more ambitious test program was conceived with improvements in the array of sensors utilized, sample mounting methods, data acquisition systems and hydraulic test conditions. The test program was divided in two parts, the first with pressure sensors mounted on the suction side of blade #4, a well eroded blade, ta identify the type of cavitation present and its aggressiveness in terms of pressure pulses. In the second, polished metallic samples were mounted in place of the sensors for pitting studies. This experimentation program took place in June 1995. 534 E. Cabrera et al. (eds.), Hydraulic Machinery and Cavitation, 534-543. © 1996 Kluwer Academic Publishers. Printed in the Netherlands.