Analysis of the blockage effect on a cavitation tunnel using CFD tools

This paper aims to analyze the tests of blockage effect on Cavitation Tunnel propellers from Institute for Technological Research, IPT, using Siemens commercial CFD (Computational Fluid Dynamics) software STAR-CCM+. The tests presented a relation between the propeller load, the tunnels geometry, the cavitation pattern and the blockage effect. This investigation is conducted in three parts. Firstly, a numerical model without the influence of the walls is conducted to investigate several numerical parameters, such as mesh and turbulence model. In the second part, the numerical model is expanded to include different cases of blockage ratio and advance ratio. A steady-state simulation is conducted, without cavitation model. The results are corrected with potential analysis of blockage correction, showing that this correction is satisfactory. In the last part, blockage simulations with cavitation model are conducted and blockage correction with cavitation is verified, resulting, again, in satisfactory results. However, it can be noted that there is a high influence of blockage ratio in the cavitation area, not contemplated in the classical blockage correction.