Numerical investigation on the asymmetric propeller behavior of a twin-screw ship during maneuvers by using RANS method

Abstract

Aiming to improve the safety of ship navigation and main engine operation, the propulsive loads are investigated for a twin-screw ship under the maneuvering condition by using CFD method. The proposed models that describe the propeller performance during ship maneuvers are summarized. Taking the twin-screw ship model DTMB 5415M as the study object, RANS simulation is performed for a series of static drift tests and rotating arm tests. The computed propulsive loads are validated by the available experimental data. The contours of axial velocity and vortex around the hull are presented to demonstrate the influence of upstream hull on the inflow to propeller under the maneuvering conditions. The details of the velocity field around the stern provide a deeper insight into the hydrodynamic mechanism of ship wake affecting the propeller performance. It is shown that the propeller behavior is highly related to the vortices shedding from the hull and appendages, which would change remarkably with the propeller position (windward and leeward) and the maneuvering motion (drift and turning). Finally, a regression analysis is performed with the proposed propeller models, and a reasonable composite model describing the asymmetric propeller behavior of a twin-screw ship during maneuvers is obtained.