Hydrodynamic performance of a Magnus anti-rolling device at zero and low ship speeds

Abstract

Excellent seakeeping performance is the basis of safe ship operation. An anti-rolling device employing swinging rotating cylinders based on the Magnus effect can provide anti-rolling measures at any ship speed. In this study, the operating principle of a Magnus anti-rolling device was examined by studying its hydrodynamic performance using large eddy simulation method. A dimensionless parameter—the rotation to swing ratio (i.e., the ratio of the rotational speed to the swing speed of the cylinder)—was proposed for use in the hydrodynamic analysis. The changes in lift-drag characteristics and wake-flow field of the Magnus anti-rolling device were observed at zero and low ship speeds according to the swing angle, angular velocity, and rotation to swing ratio. The influence of the relative incoming flow velocity on the hydrodynamic characteristics of the Magnus anti-rolling device, when swinging upstream and downstream, was also studied at a low ship speed. The results show that an optimal rotation to swing ratio can be obtained at zero speed, and that the differential swing method can provide a large and consistent lift at low speeds. This analysis of the hydrodynamic characteristics of the Magnus anti-rolling device contributes to the study of ship seakeeping strategies.