Análisis del desgaste superficial en los álabes de un rodete francis mediante simulación por elementos finitos en la interfaz del material metalizado y no metalizado: caso de estudio – San Francisco

Abstract

The lack of information regarding surface wear at the micrometric level on the blades of a Francis runner led to the analysis of surface wear on the blades of the Francis runner at the San Francisco Hydroelectric Power Plant, through finite element simulation at the interface of the metallized material and not metallic. The project began with the extraction of a blade section that allowed a detailed study of its morphology at a micrometric level. With the help of the CIRT scanning electron microscope, it was possible to obtain the morphology of the anchoring profile of the base metal, metallization layer and external profile. Solidworks software was used to perform 3D modeling of the extracted blade section including details of its morphology. By means of CFD simulation with the Flow Simulation tool, 3 different study scenarios were generated: the Francis turbine assembly, which allowed observing the behavior of the fluid on a macro scale inside the impeller, a 3D model without surface wear and a 3D model with surface wear in the metallized layer. With the simulation it was found that the fluid properties change in their numerical values when there are sudden changes in section, either by erosion of the material due to previous cavitation or by areas of the metallized layer with excess thickness. The deltas of variation in the values of the density and temperature of the fluid were minimal, that is the reason why they were considered negligible assuming that these properties are constant throughout their trajectory inside the turbine. It is recommended to work with a standard thickness of 250 μm for impeller metallization procedures, since areas with greater thickness become stress concentrators, generating cavitation conditions that affect the impeller blades.