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CFD simulation of loadings on circular duct in calm water and waves

Stringent rules and regulations to reduce ship environmental footprint and continuous aim to improve the propulsion efficiency stimulate development of different technical solutions. Typical technical solution that reduces ship total power needs (particularly for the propulsion) is the Energy saving device (ESD), i.e. special hydrodynamic appendage installed on the ship aft body. In this paper, the hydrodynamic loadings on circular duct (one of typical ESDs) of a bulk carrier are analysed in calm water and waves by CFD. To reduce the CPU time, actuator disk model is used instead of the direct propeller simulation. Effect of the actuator disk on the pressure distribution is investigated and discussed. Results are compared to available experimental measurements in calm water (wake field, resistance, self-propulsion) in order to validate the proposed simplified model. Additional simulations are performed in waves and a detailed evaluation of duct loadings is presented along with the duct performance in waves. Simulations are performed by means of OpenFOAM. Findings display a significant effect of the propeller suction on the ESD pressure distribution indicating its importance when assessing the structural reliability of the ESDs both in calm water and waves.

Energy saving device ; ship hydrodynamics ; actuator disk ; CFD ; duct

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