Research On Hydrodynamic Characteristics Of A New Raft-type Wave Energy Platform

Since the beginning of the 21st century,the dependence of the world's traditional fossil energy sources on petroleum,natural gas and coal has been gradually increased.The contradiction between the steady improvement of comprehensive national power and the shortage of energy has become increasingly prominent.Haze and other fossil energy sources of secondary pollution continue to plague the people around the world,which is one of the problems the government need to solve.Renewable green energy sources such as ocean energy,solar energy,and wind energy are beginning to emerge on the world stage,where wave energy has some advantages such as high energy density,low environmental impact,low energy loss.These advantages make the wave energy resources in the field of new energy more and more get the favor of all countries in the world.Because our hydrological and wave conditions are different from those of foreign countries,we can not apply the successful experience of other countries directly.We must design a set of wave energy generating devices which are suitable for China's sea conditions according to the characteristics of wave energy resources in China.Based on the actual situation in China,a new multi-functional modularized raft-type wave energy generation platform is proposed.The hydrodynamic and fluctuating displacements of the device in the vertical direction which influence the capture energy efficiency are studied and analyzed,which provide reference for the subsequent structural optimization and hydraulic design.The contents of each chapter are summarized as follow:The first chapter mainly expatiates on the distribution and utilization of wave energy resources in China and the background and significance of the study on wave energy generation devices.The main research approaches and research ideas of several different types of wave energy generation devices and hydrodynamic performance at home and abroad are introduced.The second chapter uses the micro wave amplitude model of linear wave theory,and according to the basic equations of micro amplitude wave theory,the boundary conditions and the velocity potential function to analyze the motion characteristics of fluid particle waves.The expressions between the parameters in different depth is obtained,and is the basis of mechanical and hydrodynamic mathematical model of follow-up system.In the third chapter,the main design functions,the overall construction technical route and the structural design scheme of the new type of raft wave power generation platform are presented.According to the design wave condition of wave power generation platform,dynamic mathematical model in horizontal cylinder under the pontoon in waves is established.And the magnitude of the vertical wave force of the working cylinder under different design wave conditions is calculated according to the assumption of Froude-Krylov.In the fourth chapter,from the point of view of dynamics,this paper analyzes the space force of the raft-type wave energy generating device proposed in this paper.Based on the second kind of Lagrangian equation,the fluctuating displacement and draft of the working buoy of the wave power plant are calculated by using the coupled mathematical model and the formula of fluctuating displacement of the floating structure on the sea.In the fifth chapter,the hydrodynamic simulation of the basic unit buoy of the wave power plant is carried out by using CFD software.The vertical displacement and hydrodynamic changes are obtained.The theoretical calculation results and CFD software simulation results are compared and analyzed systematically.In the sixth chapter,the main research contents and the work of each chapter are summarized and prospected.