Abstract No.C180503-253

Author name(s): Yunlong DU, Kunpeng CHEN, Weimin CHEN, Xiaping CHEN, Guoxiang DONG

Company: State Key Laboratory of Navigation and Safety Technology, Shanghai Ship & Shipping Research Institute, China

Pre-duct fitted upstream of the propeller, if designed properly, could be an effective energy saving device to support the propeller performance for fuller ships such as bulk carriers and oil tankers. In this paper, a bulk carrier with a pre-duct was chosen as the research object to study the working mechanism of the pre-duct. Numerical simulation method was adopted and resistance and self-propulsion simulations were carried out with the pre-duct fitted on the ship model or not. During the simulations, the ship hull, rudder, propeller and duct were all modeled explicitly. Flow details with and without the pre-duct were extracted from the simulations. Based on simulation results, the pre-duct brought only 0.12% increase in the ship model total resistance. Flow field changes can be found in the propeller disk which would be good for the propeller working condition. The average value of axial wake in the propeller disk was increased and the bilge vortices and peaks of tangential flow were weakened by the duct, which means the pre-duct homogenized the axial flow and the cross flow heading for the propeller. Due to the asymmetrical design of duct on the port side and starboard side, the pre-duct generate a pre-swirl flow against propeller rotational direction based on the CFD result. Model tank tests were also conducted in SSSRI’s model basin, and the propulsive efficiency improvement determined by simulation was in line with model test results.

KEY WORDS: CFD; self-propulsion simulation; pre-duct; energy saving device; bulk carrier

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