Analysis of Stern Shape Effect on Pre-Duct Propeller Performance Based on Numerical Simulation

Abstract

In process and development of ship building, it always lead to the design that is environmentally friendly and has high efficiency values on the energy and economic side. The factor is the selection and determination of the propulsion system. In propulsion system, propeller and its flow is very influential, such as flow at the stern, the flow that will enter the propeller, and the propeller design used. This can increase the propulsive coefficient of the propulsion system. For single screw ship, the hull efficiency is usually between 1.1 - 1.4, while for twin-screw with conventional hull forms, the hull efficiency is around 0.95 - 1.05. The value of relative rotative efficiency is between 1.0 - 1.07 and the efficiency of the shaft is between 0.96 - 0.995. Meanwhile, the value of open water efficiency and hull efficiency greatly affect to ship performance. From the simulation, with the additional of pre-duct The hull efficiency value has increased by 2.2% - 4.3%, this is due to the increase of wake fraction value higher than the thrust deduction value. The relative rotative efficiency also increases by 0.8% - 1% for each variation of the block coefficient or type of ship. But, for the propulsive coefficient, the resulting gap was decreasing by 2% - 6%. Because of that the distance between the hull and the pre-duct, the design of the propeller, the distance between the pre-duct and the propeller, and the shape of the stern are important references for the pre-duct design.