In this paper, STAR CCM+ software was used to simulate the hydrodynamic performance of the freely rotating vane wheel with different number of blades. The cutting volume technique was used for meshing. The rotation of the propeller and vane wheel was modelled by sliding mesh. The Large Eddy Simulation (LES) turbulence model was used for numerical simulation. The hydrodynamic performance of the vane wheel at different rotational speed was calculated. At the same time, the vortex shape, pressure distribution and the flow field behind the propeller and vane wheel were analyzed. The results of numerical simulations showed that the number of blades of wheel has significant effect on the hydrodynamic interaction between the propeller and the vane wheel.
In recent years, in order to better limit the ship's emissions of green- house gas and achieve the goal of green shipbuilding, the IMO has proposed a timetable for the implementation of the ship Energy Efficiency Operation Index (EEOI) and Energy Efficiency Design Index (EEDI). Energy saving is a strategic long-term task for the development of the national economy, so the need for ship energy saving is also increasingly urgent. As one of notable devices, the installation of vane wheel behind the propeller has a remarkable effect, which is an effective measure in ship energy saving.
Grim (1980) conducted a series of experiments to study and compare the efficiency of vane wheel and other propulsive devices. Blaurock (1983) studied the energy saving effect of the vane wheel, the results showed that the vane wheel behind the propeller can recover part of the energy lost in the wake of the conventional propeller and convert it into additional thrust; Chen et al. (1989) used the optimal circulation distribution method to design the vane wheel, and the results of the model tests were consistent with the expected results, which can improve efficiency. De Cock (1989) explained that although the vane wheel can improve the propulsion efficiency, there were some difficulties in practical applications. On the one hand, the efficiency of the propeller and vane wheel system must be maximized; on the other hand, the vane wheel must be guaranteed with sufficient strength; Tanaka et al. (1989) described a large vane wheel with a diameter of 11.64 meters, which was improved based on the design of Grim. A large vane wheel was used on a large cruise ship for energy saving, and the improved vane wheel was described in detail. Xiao et al.(1996) studied the effect of parameters such as diameter ratio, speed ratio, and distance between propeller and vane wheel on the hydrodynamic performance of propeller and vane wheel systems. The results showed that the hydrodynamic performance of the system is better when the propeller was subjected to a larger load.