Experiments and CFD Analysis on Safe-Return-to-Port of a Damaged Ship in Head and Following Seas

In the present study, model tests in a towing tank and computational fluid dynamics (CFD) analysis on damaged stability of a passenger ship in waves were conducted. An autopilot system that controlled the rudder angle was introduced to the test model, for course-keeping maneuverability of the test model in asymmetric damaged condition. Following the regulations of the safe-return-to-port (SRTP) of passenger ships, the ship speed in the test corresponded to 8 knots in the full scale. In the damaged condition, a compartment at midship was flooded and the stability of the model degraded. Tests were conducted in head and following seas. Wave conditions correspond to Sea states 4 to 6. The six-degrees-of-freedom (6DOF) motion response of the test model was measured by a wireless inertial measurement unit and gyro sensors to achieve fully untethered model tests. Thrust and torque on the propulsive system and free-surface height in the damaged compartment were also measured. CFD analysis was performed in the same condition as the experiments. 6DOF motion, the propulsion, and flooding behavior were analyzed. CFD analysis results were compared with the experimental results. In addition, some physical features that could not be measured by experiments were identified and investigated. With the results of the experiments and CFD analysis, the effects of incoming waves and flooding behavior on the propulsion and seakeeping performance of the damaged ship model could be identified.