Design And Fluid-structure Interaction Analysis Of Bend-Twist Blade Of Horizontal Axis Tidal Turbine

There is a growing interest in renewable energy due to the limitation of fossil fuel resources and the environmental impact of their utilization. Tides or ocean currents, in particular, are regarded as a potential source of renewable energy. Due to environmental concerns regarding potential devices it is thought that a breakthrough will occur in the area of kinetic energy devices, most likely horizontal axis tidal turbines (HATTs). It is an increasing trend in the marine industry to use composites to improve the hydrodynamic and structural performance of naval structures. Composite materials have high strength-to-weight and stiffness-to-weight ratios, and the fiber orientations can be exploited to tailor the structural deformation to reduce the load and stress variations by automatically adjusting the shape of the structure.At first, in this thesis, the research object was the horizontal axis turbine blade, starting with the overview of horizontal axis turbine. And then it introduced the current domestic and foreign studies in recent years, fluid-structure interaction, methods and results of proposed studies methods, studies ideas and studies content. Secondly, this thesis briefly described main parameters and the mechanics and motion characteristic of the turbine blades, gave dimensionless parameters which have an impact of turbine performance. And then it discussed three studies methods of the horizontal axis turbine blades, including blade element momentum theory, computational fluid dynamics (CFD), and vortex wake theory, and the analysis of advantages and disadvantages of each type of studies method. Next, based on CFD and continuous finite element analysis (FEA) method, one-way fluid-structure interaction(FSI) method of horizontal axis turbine blades was established via CFX and ANSYS Mechanical. Then numerical simulation results of steady and transient calculation methods were compared. On the other hand, the result of a one-way FSI method was made a comparison with the results based on blade element momentum theory, which is to verify the accuracy of this method. In the following two chapters, bend-twist of horizontal axis turbine blade which was made up of composite material was designed based on bend-twist coupling theory. And then ply thickness of the blade design was optimized based on Lagrange nonlinear programming method via Workbench. 6% of the blade mass amount was reduced by the optimization which made sure that the structural safety of the premise of the blade. On the other hand, structural performance, bend-twist performance and vibration characteristics of the optimized blade were analyzed via one-way FSI method, and the FEA results showed that the structural strength of the blade met the strength requirements and pointed out hazardous areas of the blade. In the last chapter, two-way FSI method of horizontal axis turbine blades was put forward, which was based on CFD theory and FEA theory. The method was created by the information exchange between fluid domain and the structural domain. And using the method in this chapter was designed to verify the level of improved hydrodynamic performance of the bend-twist blade, and the results indicate that the deformed blade of bend-twist reached an 8% increase of energy capture ratio.