Hydrodynamic Analysis Of Floating Breakwater Integrated With Wave Energy Converter

In tackle with severe energy problems,people begin to explore and develop renewable energy.In terms of current research progress,wave energy utilization technology is still far from practical engineering application.The lower cost of wave energy converter can enhance its market competitiveness.The integrated device of floating breakwater and wave energy converter is a kind of cost-sharing strategy which is spatial-sharing,cost-sharing and performance combination.This makes the engineering application of wave energy capture more feasible.In this paper,a conceptual design scheme of integrated device with box floating breakwater and oscillating buoy type wave energy converter is proposed.The coupling motion response,wave attenuation and energy capture performance and mechanism of the integrated device under the action of regular wave and mooring chains are studied.In this paper,the variation and interaction mechanism of hydrodynamic characteristics,wave attenuation performance,energy capture efficiency under different configuration factors of integrated devices and the most common sea conditions are analyzed,and the configuration parameters with better comprehensive performance are selected.Based on that,the hydrodynamic performance,wave attenuation characteristics and energy capture efficiency of the integrated device under variable wavelength and wave height conditions are studied,and the wave attenuation characteristics are compared with those without the buoy.The influence and interaction principle of oscillating buoy on the wave attenuation characteristics of the integrated device are analyzed,and the comprehensive performance of the integrated device is finally evaluated.In this paper,ANSYS Fluent software based on viscous flow computational fluid dynamics theory is used.Through the quasi-static theory of mooring line,multi-body coupling dynamics theory,Newmark-? method and other theories and methods,the factors are grouped according to their properties.The coupling hydrodynamic analysis and performance calculation of the integrated device are carried out by combining the joint influence and control variables.The research shows that the increase of Coulomb damping has stronger inhibitory effects on the wave energy absorption capacity and oscillation response of the buoy than that of the linear damping.When the mass of the buoy is small,for the linear damping,the change of the buoy oscillation response has little effect on the wave attenuation performance of the integrated device,while the energy capture efficiency decreases.For the small buoy mass and Coulomb damping,the energy capture efficiency of the integrated device is reduced.The sensitivity to the variation of Coulomb damping is reduced,and the change of transmission coefficient is also mitigated.When the inlet of the attenuation channel is completely submerged in the water,the wave attenuation performance of the integrated device is slightly reduced and the energy capture efficiency is relatively higher.With the increase of outlet width,the oscillation of buoy is disadvantageous to the energy capture efficiency and increases the transmission coefficient.Compared with the flat bottom,the moonpool effect of the floating breakwater is reduced,the energy capture efficiency of the integrated device is reduced,and the wave attenuation performance gets worse.When the moonpool width increases,the energy capture efficiency of the integrated device is higher.With the increase of wavelength,the energy capture efficiency of the integrated device is overall decreased,and its change fluctuates.The buoy in the integrated device enhances the wave attenuation ability and changes it more smoothly,but in the long wave case,the positive effect is not obvious.With the increase of wave height,the wave dissipation capacity of the integrated device decreases slightly,the buoy oscillation response increases gradually but becomes more unstable,and the increase amplitude decreases gradually.The energy capture efficiency of the integrated device also decreases accordingly.The buoy has a positive effect on the wave attenuation performance of the floating breakwater,but it is reduced to naught with the increase of wave height.It is found that the integrated device has the best working efficiency under suitable sea conditions,while the energy capture efficiency does not increase under harsh sea conditions,which will increase the risk of damage to the integrated device structure or mooring system.The hydrodynamic and performance analysis of the novel integrated device provides ideas and reference for the subsequent research on the coupling hydrodynamic model of wave attenuation and wave energy conversion.