Erosive wear of prototype-scale Pelton turbines

THE PROBLEM
The erosive wear of hydraulic turbines, especially Pelton runners and injectors, is a common issue that results in efficiency degradation, enhanced cavitation and the need for expensive repairs. The technical capacity to predict the erosion process of prototype-scale machines is instrumental to the optimization of the runner designs and operation strategies of hydroelectric plants. However, the simulation of this phenomenon is particularly challenging due to its multiscale nature. In this context, the Laboratory for Hydraulic Machines (LMH) at EPFL, with the support of several Swiss research funding agencies and an industrial partner, GE Renewable Energy, has recently developed a multiscale modeling and simulation methodology aimed at providing accurate predictions of the erosion process of hydraulic turbines. The project involved developing a GPU-accelerated in-house simulation software, characterizing the stainless steel typically used in these hydraulic components, running multiscale simulations of laboratory-scale and prototype-scale erosion test cases, and validating the results obtained in order to assess the model reliability, transferability and accuracy. According to these results, the proposed multiscale model is significantly more accurate than the state-of-the-art erosion models that are based on empirical correlations.