Numerical Study On Ship Hydrodynamic Performance In Restricted Waters

The large-scale,intelligent and rapid development of ships are development trend in the future.In order to meet the requirements of shipping companies for economic benefits,shipbuilding companies continue to increase the main dimensions of ships.Relatively speaking,the waterway’s remediation has been relatively slow,such as canals,inland waterways,wharves.From the perspective of large ships,because of the shallow water and narrow channel,it is called restricted waters.When ship is sailing in the restricted waters,due to the compression of the flow field at the bottom of the ship or at the left and right sides of the ship,the speed of water flow is accelerated and the pressure drops,the ship hydrodynamic performance changes significantly,causing the ship to swing violently.If the ship is operated improperly,it is very likely to have safety accidents and cause unnecessary economic losses.Therefore,it is necessary to conduct numerical research on the complex viscous flow field and hydrodynamic variation law of ships sailing in restricted waters.In this paper,the standard oil tanker KVLCC2 is taken as the research object.The commercial software STAR-CCM+ is used and fixed the ship model with six degrees of freedom.The complex viscous flow field and ship hydrodynamic performance are simulated by solving the RANS equation.In order to verify the feasibility of the numerical and grid generation method,the grid independence verification,turbulence model verification,resistance coefficient under different water depths and stern flow field under shallow water conditions are carried out.Then,the influence of different water depth,ship-bank distance and speed on hydrodynamic force,hull surface pressure and wave making are analyzed,and the deviation of wake field is analyzed emphatically,and variation rules are summarized.Then,the propeller and rudder are introduced,and the hydrodynamic and viscous flow field of the hull-propeller-rudder system navigation in restricted waters are numerically simulated.Firstly,the resistance of the hull-rudder system,the open water performance of the propeller and the self-propelled performance of the hull-propellerrudder system are numerically verified,which are in good agreement with the experimental data.The grid independence of the hull-propeller-rudder self-propelled is verified,and the reliability of the sliding grid to deal with the propeller rotation is verified.Then,the numerical comparison of hydrodynamic force,surface pressure and wave making of hull-rudder with and without propeller is carried out.Finally,the bearing force,rudder force,fluctuating pressure and vorticity field evolution of the propeller are numerically simulated,which further explains the influence of different water depth and ship-bank distance on the hydrodynamic performance sailing in restricted waters.In this paper,combined with the sliding grid technology,considering the influence of free surface and viscous fluid,the complex flow field and hydrodynamic performance around the ship in restricted waters are numerically simulated.The simulation results more truly explain the changes of hydrodynamic and flow field when the ship is sailing in restricted waters,which is helpful to improve people’s understanding and cognition of the ship hydrodynamic performance when the ship is sailing in restricted waters.