As a newly developed propeller, the whale tail wheel (WTW) has potential applications in the field of ship energy saving. The study of the WTW performance is carried out via theoretical analysis and CFD simulation. Firstly, the relationship between the propeller's geometry parameters, motion parameters and performance parameters are established by theoretical analysis. With this newly developed model, the hydrodynamic performance of a self-designed WTW is investigated under different working conditions. Secondly, a CFD model is developed to study the performance of the WTW under typical working conditions. The computed results are compared against the theoretical results. The difference between the theoretical results and the CFD results is analyzed, and some suggestions on the selection of optimal working condition are given.
WTW consists of a set of parallel arranged blades at the stern. When it works, the blades rotate around the shaft together with the rotor and swing around their own axes. When it moves forward, the trajectory of the blades in space is a cycloid. As an attack angle is formed between the blade and the inlet flows, the lift component on the forward direction is thrust.
Compared to the traditional propeller, the WTW has the advantages of high efficiency and better anti-cavitation performance due to the smaller blade load. Thus, the WTW has a potential application in low-speed ships.
The WTW belongs to one type of cycloidal propeller, while the current research focus mainly on another type of cycloidal propeller, named the VSP (Voith Schneider Propeller). W.Just (1939) first used the blade element theory to calculate the VSP hydrodynamic performance. The results showed a good agreement with the experimental results obtained by Voith. Mendenhall and Spangler (1973) in the United States, proposed an unsteady model based on the circulation theory to calculate the hydrodynamic performance of VSP. In recent years, with the development of CFD technology, the Voith company (Bartels and Jürgens, 2006; Bartels and Jürgens, 2004; Juergens and Moltrecht, 2003) used the software COMET which is based on the finite volume method to study the performance of VSP, the flow field and the pressure distribution of blades were obtained, which provided an important basis for the design and optimization of VSP. As another branch of cycloidal propeller, the WTW research started late, and the relevant research results are insufficient. Manen (1966) and Ficken (1969) had carried on experiments to compare the performance of the WTW under different blade swing modes; MARIN firstly extended it for ship application based on the model test (Anon, 1998).
