Structure Design And Analysis For The Bi-Directional Blade Of Horizontal Axis Marine Current Turbine

The rapid depletion of energy and the acceleration of socio-economic development make energy transition an inevitable choice for sustainable development.And marine current turbine(MCT)has become key research object by many countries in the past decades due to its development superiority.As a backbone for the development of marine current energy resources,horizontal axis marine current turbine has a great research space on how to makes it more efficient to use bi-directional marine current to generate electricity.In this paper,a bi-directional blade of 500W horizontal axis marine current turbine was regarded as a design object.And in order to explore the rationality and feasibility of bi-directional blade design,the paper mainly researched from the aspects of reversible airfoil design,hydrodynamic structure design,ultimate load analysis,finite element analysis of blade structure and performance analysis of bidirectional rotor.The contents of each chapter are as follows:The first chapter introduced the research background of the subject,and fully investigated the current research status of the marine current turbine and bi-directional blades in the world.Finally put forward the significance and contents of research.The second chapter analyzed the basic theory of bi-directional blades design for marine current turbine,mainly including the basic theory of airfoil,the elemental-momentum(BEM)theory and the bi-directional blades design theory based on the S-shaped airfoil.Then,the basic theory of computational fluid dynamics(CFD)was deduced to use for numerical simulation.The third chapter,bi-directional airfoil was constructed according to the theory of bi-directional blade and the CFD method was used to simulate and analyze the flow around two-dimensional airfoil.The airfoil with better performance was obtained.In addition,the pressure distribution and lift-drag features of the preferred airfoil were further analyzed.In the fourth chapter,the blade hydrodynamic structure model based on the BEM theory were established and solved out.Then the ultimate load of rotor was calculated by Tidal Bladed model.Based on this,mechanical structure of bi-directional blades were designed and verified.Including the design of root structure,the selection of bolt,the checking of the static strength,the disturbance and the calculation of the natural frequency.In the fifth chapter,the power capture coefficient,axial thrust coefficient and surface cavitation of the 500 W horizontal axis bidirectional rotor were analyzed,based on BEM and CFD method,to evaluate the performance of bidirectional blade and verify the rationality of bidirectional blade design scheme.The last chapter summarized the research work of the thesis,and put forward the further research direction.