Numerical Modeling of Sheet and Tip Vortex Cavitation with Fluent 5

Abstract

This paper presents numerical work made with the commercial CFD code Fluent 5 by Fluent Inc. The main investigation constitutes a 2D NACA 0015 hydrofoil grid. The grid is designed to resemble a physical setup found at Saint Anthony Falls Laboratory (SAFL) in Minneapolis, MN, USA. The study is done for cavitation numbers ranging from inception to supercavitating at two different angles of attack. All numerical results are compared to corresponding experimental results from the SAFL tunnel in a quantitative manner. The general characteristics of the cavitating flow was very well predicted. Especially, the cavity length is calculated with high accuracy. Lift variations as a function of cavitation number are also reasonably well predicted. The current model, however, seems to have problems with the dynamics of the system. The next section presents a 3D calculation on a NACA 66_2-415 elliptical planform hydrofoil. This was done primarily to investigate the 3D ability of the solver. The results are validated with experimental data. Special focus is given to tip vortex strength and lift variation as a function of cavitation number. Both are well predicted.