Mechanism of sailing safety through bridge area based on a coupled hull-propeller-rudder model

Abstract

The safety of ships sailing through bridge areas has received significant attention, and the ship model without propeller and rudder (H-model) is widely used nowadays. To further elucidate the sailing mechanism in the bridge area, a coupled hull-propeller-rudder model (C-model) is proposed. Specifically, secondary development based on Fluent is undertaken. The governing equations of the ship are embedded using the user-defined function (UDF) module, and a modified multiple reference frame (MRF) model is employed to solve the coupled translational and rotational motions of the propeller. Compared to the motion parameters obtained by the H-model, the additional flow-mediated interactions among the propeller, rudder and pier lead to a smaller yaw angle and a greater lateral displacement. The reasons for these changes are given by analyzing the flow evolution and ship motions. The effects of flow velocity and ship velocity are also given. In front of the pier, the lateral displacement and yaw angle of the ship increase with the flow velocity and decrease with the ship velocity. Behind the pier, the yaw angles increase continuously under conditions of the low flow velocity and high ship velocity, thereby increasing the risk of the stern of the ship sweeping against the pier.