Numerical Simulation Of ONRT Tumblehome Ship Sailing Performance In Waves

The rapid development of computer science has driven the progress of many fields,and computational fluid dynamics software has gradually become import research tool in the field of naval architecture and ocean engineering.Numerical simulations mainly were carried by commercial software in domestic,so an in house CFD code which aim to predict performance of ship hydrodynamic were developed by Ship Hydrodynamic Performance Research Group of Huazhong University of Science and Technology.All simulations were investigated using HUST-Ship based on overset grid technique.The RANS governing equations have been discretized with finite difference method.Turbulence models used the anisotropic two equations Shear Stress Transport(SST)k-ωmodel.Two methods were used for propeller modeling: the first is the body force method using Osaka University Method(OUM),while the second is based on a 3D fully discretized propeller using dynamic overset grid technique.The simulation of ONRT resistance,openwater characteristic of ONRT propeller,self-propulsion performance in calm water and wave,the turning maneuvering in calm water and wave are carried out in this paper.Simulations of ONRT ship resistance were investigated in different Fr and the results show good agreement with experimental data.The predicted data of propeller open-water performance in different advance coefficient show agreement with the data provided by IIHR.The trust coefficient is higher than experimental data when the propeller load is low,and the opposite is true when the propeller load is high.The self-propulsion point of ONRT in calm water was good agreement with experimental data,which is shown that HUST-Ship enables predict ship hull-propeller-rudder interaction.Because the 3D fully discretized propeller using dynamic overset grid technique truly simulate the phenomenon of propeller suction effect behind the ship,the rotational speed,sinkage and trim can better predict using discretized propeller than OUM.The ONRT self-propulsion in regular head wave was investigated using the discretized propeller and OUM body force method,respectively.The high frequency vibration generated by propeller rotation was only shown in trust coefficient curve obtained by discretized propeller method.The average ship velocity,sinkage amplitude and trim amplitude are good agreement with experimental data,and the average ship velocity obtained by two methods is lower than experimental data.The reason may be that RANS approach result in larger viscous effect,so larger resistance was predicted.Trust coefficient of body force is obtained by potential flow theory,so the average ship velocity is slightly higher than that calculated by discretized propeller method.The simulation difference of the characteristic parameters of ONRT turning in calm water or waves are below 10%.