Implicit Large Eddy Simulation for Unsteady Cavitating Flow around hydrofoils using OpenFOAM software

Abstract

Cavitation simulation allows to understand the generation of this phenomenon in turbomachinery. The present thesis analyzes the cavitating flow around Francis-99 turbine blades using OpenFOAM software. The study include an analysis of the phenomenon of cavitation, a description of the open-source software used, the explanation of a methodology and the process to obtain the simulations results; starting from the points of the blade obtained in Blender, to reach with GMSH a refined structured mesh to be simulated. The solver use Implicit Large Eddy Simulation (ILES) method and Zwart cavitation model, it was obtained from PhD. candidate of Tsinghua University, engineer Victor Hugo Hidalgo, MSc. A similitude analysis was performed to prove the behavior of the cavitating flow varying the angle of attack, size of the mesh and cavitation number. The analysis of the different behaviors of the cavitation when vary the section of the blade are also presented. Finally is included a mesh with the guide vane and blade of the turbine to analyze the behavior in time. To validate the meshes are used some parameters like the Yplus, y+ and Courant, C, numbers and was performed a hexahedral quality mesh distortion analysis. Results show the similitude in the behavior of the cavities with proposed experimental data, an assessment of the study of the cavitation phenomenon and a determination of the behavior of the cavities volume generated in time to reach minimums and maximums.