Study On Hydrodynamic Performance Of Suspended Pendulum Wave Power Generator

Currently,wave energy has become one of the most important renewable energy sources in the world.Suspended pendulum wave energy conversion device is a small structure.It has the characteristics of low investment cost,easy monitoring and maintenance.Therefore,it has great development prospects.In this paper,the interaction between suspended pendulum and wave is studied,and the variation law of its hydrodynamic performance is explored.For the suspended pendulum which is impacted by waves for a long time,the pendulum is easy to be damaged and the service life of the pendulum is reduced.Therefore,by arranging rectangular holes regularly on the pendulum,the horizontal force of the pendulum can be reducedFirstly,it is necessary to verify the wave stability of numerical flume and the fitting degree with the wave of experimental flume.In this paper,STAR-CCM+software is used to build two-dimensional and three-dimensional numerical wave flume,which is compared with the wave attenuation ratio of physical test,and the results fit well.At different wave heights,the numerical simulation results of pendulum angle of suspended pendulum are compared with the experimental results.The fitting result of swing angle amplitude is good,which proves that the selection of numerical model is reasonable and can satisfy the practical engineering application.In two-dimensional case,the influence of the ratio of length to wavelength of water chamber is studied.It is found that when the ratio of length to wavelength is 1/4,the horizontal force of the pendulum reaches the minimum value;when the ratio of depth to depth of water is 1/5,the pendulum angle reaches the maximum value and the horizontal force is the minimum;when the load damping coefficient of the pendulum is changed under specific wave conditions,it is found that when the wave period is 1 s,the horizontal force of the pendulum reaches the minimum value.When the load damping coefficient is 0.0098 Nmsrad-1,the maximum wave energy conversion efficiency of suspended pendulum is 21.8%.The influence of wave period on the negative swing angle of pendulum is small under the condition of fixed load.When the natural period of the pendulum is consistent with the wave period,the horizontal and vertical forces of the pendulum decrease with the decrease of the initial phase angle,but the conversion efficiency of wave energy increases.With the increase of wave period,the swing angle of the pendulum increases with the maximum horizontal force,the vertical force decreases,and the conversion efficiency of wave energy increases.With the increase of swing,the horizontal force of the swing plate decreases,and the vertical force increases gradually.When the horizontal and vertical forces of the pendulum reach the maximum,the pendulum angle increases with the increase of the swing amplitude.With the increase of the swing,the wave energy conversion efficiency of the swing plate increases,but the variation is small.With the increase of the ratio of wave height to swing amplitude,the horizontal and vertical forces of the swing plate increase,and the efficiency of wave energy conversion also increases.However,it has little effect on the negative moment of the swing plate axis.To sum up,in practical engineering applications,the swing angle position can be avoided when the swing plate is subjected to the greatest force,so as to prolong its service life.An optimization scheme is proposed to improve the reliability of suspended pendulum,in which rectangular holes arranged regularly are arranged on the pendulum.Under the condition of no load,the effect of the porosity of the pendulum on the hydrodynamic performance of the porous pendulum is studied.With the increase of the porosity,the horizontal force of the pendulum decreases obviously,and the pendulum angle changes more stably.Under load condition,the wave energy conversion efficiency of suspended pendulum decreases with the increase of porosity.When the porosity is 10%,the wave energy conversion efficiency is 18.5%.However,the horizontal force along the wave direction of the pendulum is 2.81N,which is 32.4%lower than that of the non-porous pendulum.Therefore,the selection of appropriate porosity is conducive to the sustainable use of pendulum wave power generation devices.