Multi-body Coupling Response And Performance Analysis Of Planetary Floats Type Wave Energy Converter

Due to the problems of environmental pollution and energy deficit,the development and utilization of re newable energy have received strong attent ion by more and more countries.Benefiting from the advantages of wide distribution,large reserves,renewable and no pollution,wave energy has received extensive attention.Multiple Wave Energy Converters(WECs)system based on floating or semi-submersible platforms is an important development direction of ocean energy utilization.However,there are few studies on multi-float wave energy converters,and most of them are based on potential flow theory,without considering the influence of viscosity.In this study,a three-dimensional numerical wave tank was established to simulate the wave-float interaction based on the Reynolds-averaged Navier–Stokes equations and the k-? Two-Layer turbulence model was applied.In this paper,the convergence of mesh scale and time step of viscous three-dimensional numerical wave tank is first studied,and compared with the published numerical and experimental data.Secondly,a series of physical model tests are carried out and comp ared with the numerical simulation.The results show that the three-dimensional numerical wave tank in this paper has good stability and accuracy.Then,the resonance condition of a particular float was solved by both numerical and analytical methods;The numerical and the analytical results are mutually verified in good agreements,which verify the reliability of the analytical process.Furthermore,a wave energy converter(WEC)consisting of a single float without damping constant was adopted,and its hydrodynamic performance in different wave conditions was investigated.It was found that the damping factor can affect the motion response of the float and the wave force it receives.Under a certain wavelength condition,the WEC resonates with the wave,at which the wave force on the float,displacement of the float and other parameters reach a maximum value.Next,the influence of linear damping constant on the power take-off(PTO)was studied.The results show that the damping factor does not affect the wave number turning point of the optimal damping constant.Finally in this paper,the present study undertakes a numerical investigation on multi-body hydrodynamic interaction between an octagonal platform and point absorber type wave energy converters utili zing CFD.By analyzing the hydrodynamic performance and absorption power of WEC system with different connection forms under different wave conditions,the fixed-type WEC is determined as the next research.Then this paper analyzed the hydrodynamic performance and absorption power of the fixed-type WEC when the angle between the float arm and the waterline is different and the angle between the float arm and the incident wave direction is different.It is found that the relationship between the float arm an d the incident wave direction has a significant impact on the motion response and absorption power of the WEC system.Finally,the coupling calculation and analysis of the octagonal platform with multi-DOF WEC system are carried out.It is found that the h ydrodynamic performance and absorption power of the WEC system will be significantly affected when the multi-body coupling effect is considered.The results of this paper have a good reference value for the simulation analysis of platform type multi-float WECs.