A Power Estimation Method for Hybrid Contra-Rotating Propeller Propulsion System

Due to the recent high level of environmental regulations, there has been increasing of the attention to Energy Saving technics. One of the developing energy saving technics is the Hybrid Contra-Rotating Propeller (HCRP) propulsion system. To date HCRP propulsion system has been applied to limited numbers of ships which has special order like domestic liners in Japan [1][2]. However, HCRP is promising system to be built in major ships like bulk carriers, tankers or container ship which are operated around the world in the future because of its high propulsion efficiency. One practical subject of HCRP is a power estimation method for this complex propulsion system. In these decades, several research projects treated HCRP. TRIPOD project [3][4] treated wide range of topics, which included tank test method, numerical analysis and concept validation adopting HCRP to an existing cargo ship. The mainstream of a power estimation method for HCRP is the way how a total force of two propeller acting as a CRP are treated as pseudo one propeller [5][6]. The feature of HCRP is that two propellers can act independently. It means there exists infinity numbers of rotational speed rate of two propellers and a propulsion performance and a maneuvering performance depends on it [5]. If we use a propeller open water characteristics of a CRP as pseudo one propeller, we can estimate only very limited conditions which are tested in a towing tank. This paper shows the newly developed powering method which use characteristics of individual two propellers and a mutual interaction of propellers acting as a CRP. This method can estimate every condition of revolution rate which made with a feature of HCRP propulsion system. The scope of this research is constructing a tank test method and a powering method and reviewing them with surveying of an actual ship performance.