Investigation of the Effects of the Pre-Duct in a Ship on Propeller–Hull Interactions Using the CFD Method

Abstract

The power requirement of a ship propulsion system is directly proportional to the fuel consumption and the emissions released. By reducing the engine power, the fuel consumption and emissions can be reduced. One of the energy saving devices (ESDs) that is positioned in a region between the stern hull and propeller is the pre-duct. The ESD can improve the propulsive coefficient of the propulsion system. This research explains the effect of a circular pre-duct on the hull-propeller interaction. A numerical simulation uses the Japan bulk carrier (JBC) standard model for the hull and propeller. A circular pre-duct was applied to the ship with different diameters, stands, and lengths of the chord. The simulation has already been validated with the result of the resistance and self-propulsion test in the towing tank. The results show that the diameter of the pre-duct affects the water flow to the propeller. The model with 1Dp can make the positive value of the propulsive coefficient be about 1.72%. The size of the foil chord of the pre-duct can improve the performance until 2.88% at 1D 2S NS model. The stand of the pre-duct has a bad effect on the propulsive coefficient. The enlarged shape of the foil pre-duct can increase the water flow on the suction side. Also, making the diameter larger than the propeller diameter and eliminating the stand on the pre-duct make the incoming flow has no resistance or damages the rotary flow before the propeller. So that, the rampant flow to the propeller becomes larger and there are no significant obstacles until the propulsive coefficient value increases significantly.