Study On Non-linear Hydrodynamic Slamming Of Floating Ships Moving In Waves

The slamming of fluid and ship occupies an important position in the field of ship design.It relates to whether the ship is damaged in large waves and the hydrodynamic performance of the ship itself.The accurate prediction of the slamming load is related to the ship structure such as fatigue fracture and buckling deformation also has a great impact.The current forecast of slamming and slamming loads is mostly based on empirical formulas.The application of scientific and gradual methods to predict ship slamming and slamming loads is not only the requirement of the development of shipbuilding industry but also the objective need of science and technology into productivity.In this paper,the non-linear boundary element method combined with the ship motion was used to calculate the slamming load of the hull of S175 ship under a large regular wave,and good results were obtained.In this paper,the mathematical model of nonlinear boundary element method is established firstly,and the possible problems in the process of numerical simulation are introduced.The related processing methods are introduced and discussed.In the physical coordinate system,the free-flowing water was simulated,the numerical simulation results of uniform velocity into water were compared with similar solutions,and good results were obtained.The free-water simulation process needs to take the relevant method to solve the coupling situation between the fluid flow and the structure movement.Auxiliary function method is adopted to solve the external force of the wedge body and the acceleration of the wedge body during free water entry.The factors that influence the load,velocity and acceleration are analyzed and compared through the numerical simulation of the free-infiltration of wedges with different initial velocity,different mass and different lifting angles.The simulation of water entry for two dimensional objects is preliminarily realized.Then the numerical simulation of the water entry of the selected ship profile is carried out.Due to the non-linearity of the ship's profile,the problems that may appear in the simulation process are more and more serious,which makes it necessary to adopt more effective treatment methods to solve the problems in the simulation.The simulation results of influent water are compared with the experimental results and the numerical simulation results of others,and get a good agreement.A lot of related results have been obtained through the simulations of uniform water inflow,free water inflow and given water inflow at the stations 1 and 18,and a detailed analysis has been carried out.The profile of the ship into the water and its own geometry is relatively large extent.Using STF method,the ship's motion response operator under regular wave is obtained.Through the treatment of heave motion equation,pitch motion equation and wave equation,the vertical motion equation of relative wave surface at any position of the ship is obtained,and the vertical velocity equation is obtained.Combining the given vertical and velocity equations with the incoming slamming program on the ship's section,the load variation from the ship profile to the flow separation time is calculated in a cycle,and the relevant change rules and the maximum load in the slamming process are obtained.