Hydroelastic Method In Time Domain For Wave Loads Calculation Of Ultra-Large Container Ship With Forward Speed

Container ship is an important vehicle that can transport cargo at relatively high speeds at sea.Recently,the size of container ship increases very fast.Due to the increase of ship size and the extensive use of high-strength steels,the flexibility of the hull girder increases and the natural frequency of ship decreases,and for the high speed and the bow flare of container ships,slamming often occur in navigation.Consequently,for ultra-large container ship,springing and whipping are very significant.Under the influence of elasticity of hull and slamming loads,the motion and wave loads of ultra-large container ship show obvious non-linear characteristics and it is difficult to predict reasonably.Therefore,a numerical method for calculating wave loads is needed,which can take into account the characteristics of the above-mentioned super-large container ships.In this thesis,the main research work is as follows:A Rankine source method for solving the unsteady velocity potential of flow field is studied.The coupling of hull deformation and flow field is considered by adding elastic deformation to the boundary conditions of hull surface.The source and sink are arranged on the free surface to satisfy the boundary conditions of the free surface.The radiation boundary condition of Rankine source is disposed by adding a damping zone on the free surface.Based on the linear boundary element method,the singularity problem and the discrete form of boundary integral equation are studied.A four-node high-order panel method program is compiled,and the accuracy of the program is verified.A non-linear hydroelastic analysis method for wave loads calculation is studied.Considering the non-linear effect of the restoring force and incident wave force induced by variation of the instantaneous wetted surface and the slamming loads,a time domain hydroelastic analysis method for the wave loads calculation of ultra-large container ships is established.The accuracy of the numerical method is verified by comparing the computing results with those of other software and the experimental data.Taking a 21000TEU container ship as an example,the non-linearity of the wave loads,the hydroelastic response of the hull under different speeds and wave headings are analyzed.Furthermore,the springing and whipping phenomena of this ultra-large container ship are calculated and discussed.Finally,a direct calculation method of design load is proposed,which provides a reliable tool for wave loads forecasting of ultra-large container ships.