This paper reports the development of a new body-force model for the rotating propeller within viscous flow code and its application to uniform flow and propeller advancing with the angle of attack. A simplified quasi-steady blade element theory with the infinite-bladed propeller model (time averaged propeller induced velocity field) is coupled with the Reynolds averaged Navier-Stokes (RANS) code to determine the thrust and the torque distributions. The present effort aims to reduce the computational effort while keeping the effect of ship with motion in quasi-steady manner for propeller. The solid-surface effect on the propeller loading and power is also studied. Open-water validation simulations are done for the Methodical-AU type fixed-pitch propeller. Reported results show fair predictive agreement between the new body-force model and the experimental data.

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SummaryThe prediction of the propeller load fluctuations in waves, which can cause great fluctuations of engine power and revolutions, is important for ship operations. Recently the prediction of free running model advancing in waves with real rotating propeller and rudder can be done by Computational Fluid Dynamics (CFD) technique. However, the validation of these methods is not enough and it requires huge mesh density and long computational time. The new propeller body-force prediction model (OU propeller model) was proposed in particular to make the computation of free running condition easier and applied for many problems. The present work is conducted to validate the capability of OU propeller model for the condition that propeller exists near free surface in waves. For the simulations, the Reynolds Averaged Navier-Stokes (RANS) solver CFDSHIP-IOWA V4.5 is used. The propeller loads are predicted, and validated against the existing experimental data and the experiments conducted in Osaka University towing tank. The results showed that the OU propeller model works well for moderate loadings and high expanded blade area ratios.