A Study of Hydrodynamic Performance on Azimuth Thruster Around Free Surface

The importance of renewable energy is on a rapidly increasing and WTIV become a important vessel in off-shore wind power. For the DP operation, the WTIV has the azimuth thruster which is generally assembled by some parts such as leg, duct, propeller, and housing. During operating on low draft in the WTIV, especially, it is important to examine the influence of the free surface on azimuth thruster’s performance. Therefore, In this study, the azimuth thruster with free surface were mainly studied based on the numerical method. So, The immersion ratio(T/D) was defined for analyzing the influence of the free surface, where T is the distance from the free water surface to the propeller rotation axis, and D is the diameter of the propeller on the aizmuth thruster. In this study, three immersion ratios(T/D = 0.75, 1.0, and 1.25) and deep sea conditions were considered. Based on the numerical simulations, the hydrodynamic performance of the azimuth thruster, the free surface in spanwise and streamwise directions, eccentric forces and moments of propeller in the azimuth thruster were discussed