Estudio y simulación numérica de la cavitación inducida por los álabes directores de una turbina Francis con características similares a las de la central hidroeléctrica San Francisco

Abstract

The present technical to study and to simulate with numerical methods the cavitation induced by the guide vanes of a turbine kind Francis, it’s focusing on the characteristics of the hydroturbine of the San Francisco Hydropower. Initially a literature review of the phenomenon of cavitation and a camp study of the San Francisco Hydropower was carried out. For the study it was necessary, to access to operation conditions and turbine geometry. The methodology used was Computational Fluid Dynamics (CFD), to simulate the formation, growth and collapse of cavitation. In order to reduce the computational resource cost, the model has been simplified to a two-dimensional computational domain. In this study, the effect of the cavitating flow on the guide vane and the effect between the guide vane and the runner's blade have been studied. The numerical simulation was carried out using commercial software ANSYS FLUENT 18, and the structured mesh was obtained using ICEM CFD. The numerical study was performed using the Navier-Stokes equations; in a two-dimensional planar form, with RANS approximation and the turbulence model k-ω SST. The study was byphasic (liquid vapor) in its mixture module and using the Schnerr - Sauer and Zwart cavitation models. The analysis of results has been made by contour graphics, which show the phenomenon of cavitation in fraction of volume of steam. Finally, thanks to this numerical study, it has been possible to determine the places in which the cavitating flow effects with greater aggressiveness in the guide vanes and blades.