Numerical prediction of scale effect on propeller bearing force of a four-screw ship

Abstract

In case of a four-screw ship, the propellers show different hydrodynamics performance due to the asymmetric distribution of the wake. And the particularity of the scale effect on wake field for this type of ship would make a more complicated characteristics on propeller bearing force. In this paper, a numerical simulation study of scale effect on propeller unsteady bearing force of a four-screw ship was performed by employing RANS method. The load variation of the single-blade is analyzed to understand the fluid mechanism of the interaction between the propeller blade and wake flow. The larger wake field difference between inside and outside propeller disk aggravates the unbalanced load distribution for the full-scale ship. The results of propeller bearing force highlight that the fluctuation values of full-scale ship are smaller than those of model one. Moreover, the scale effect of outside propeller is strong with respect to the inside one. The above findings can provide theoretical guidance for load balancing and vibration reduction of the four-screw ships.