Added Powering Measurements of KCS Maneuvering in Regular Variable Heading Waves

Abstract

To know more detail of added powering and propeller load fluctuations in regular waves during free-maneuvering, free-running tests of KRISO Container Ship model (KCS) are conducted. KCS 2.7 m model that was used in the previous surge-free added resistance experiments is modified and new free-running system with compact dynamometer is installed. Free-running tests in calm water and in regular variable heading waves are performed at IIHR 40 m × 20 m × 3 m wave basin to obtain 6DOF motions with thrust/torque data. Propeller open water tests were performed at Osaka University towing tank (OU). To evaluate facility bias and scale effects, trajectories, motions and maneuvering characteristic parameters are compared with those of different size model taken at other facilities. Free-running course keeping tests in regular variable heading waves are performed as same conditions with Tokyo 2015 A Workshop on CFD in Ship Hydrodynamics (T2015) case 2.10 and case 2.11. Those results are compared with the data taken at FORCE with 6 m free-running model and OU with 3.2 m model by surge-free mount. In head waves, trends of RAO for heave and pitch are the same under surge-free and free-running. Added thrust/torque and propeller open water efficiency reduction of IIHR and OU become maximum at λ/ L=1.15 where the added resistance was maximum under surge-free condition. In oblique waves, added thrust and torque become larger where the wave encounter angle is from 0° to 45° and both trends agree with other type of container ship. Thrust and torque fluctuations of KCS become larger in beam and following waves. Variation of self-propulsion factors due to wave encounter angles are small in oblique waves.