| In recent years, the exploitation of tidal current energy is drawing more and more attention. As a common device used to capture the energy, the turbine can convert the tidal energy into the mechanical energy of the running blades, then into the electric energy of the dynamo. Being the crucial part to capture energy of the turbine, its property will directly determine the efficiency of the energy capture of the turbine, besides, the airfoil is the basic component of blade, as a result choosing airfoil is of great importance in the study of energy capture. Basing on the copying technology of the turbine, this thesis takes its root in bionics, aiming to apply the excellent hydrodynamic performance of the shark fin to the design of bionic blade and combinational blade, with an expectation to improve the turbine’s performance.This thesis takes the shark fin as its sample to imitate its airfoil, applying reverse engineering technology in the process of the three-dimension scanning of the point cloud data, thus acquiring the structural surface of the shark’s pectoral and caudal fins, and after that airfoils of different positions was proportionally intercepted through Solid Works, and through the selection of the airfoils of high lift-to-drag ratio and high torque coefficient by Profili, the optimal bionic blade and combinational blade was acquired. Then basing on the processes of the parameter optimization of blade and coordinate transforming by Mat lab and combining the blade-momentum theory, and the Wilson blade design theory, the bionic blade and combinational blade are created and the model of bionic shark fin turbine is built.Numerical Simulation studies the performance of turbine from the point of simulation. This thesis adopts the method of CFD, whose process includes mesh generation, calculate solution and post process. Mesh generation adopts Gambit and sets fluid domain and rotating domain according to the requirements while calculate solution and postprocess apply the professional fluid analysis software-Fluent in their processing. Through the contrastive analysis of the hydrodynamic performances of bionic, combinational and Conventional blades in changing pitch angle, then we can draw a conclusion, that at the rated speed, when the pitch angle of bionic blade and combinational blade respectively is at 70°nd 60°, the torque of turbine reaches its maximum and exceeds that of the standard blade, besides comparing the former two kinds of blades, the performance of bionic blade is the best. Apart from that, the analysis of the pressure and velocity fields of different blades come to the same conclusion.On the basis of numerical simulation, this thesis designs a variable pitch system controlled by wireless steering engine. This design includes the study of variable pitch moment and driving mode, the design of the system principle diagram and three-dimension modeling and so forth. Then the modal of bionic blade and combinational blade are produced, the variable pitch system is worked out and assembled, the experiment equipment and experiment scheme is well prepared, at last the test on the hydrodynamic performances of the turbines constituted by different blades is carried out underwater. The experimental results expected coincide with the results of the numerical simulation, their trends are similar, besides we get the important data- the rotate speeds of the turbine at different pitch angle and the same rated speed.In a word, the study of this thesis provides reference for the selection of bionic airfoil of turbine blade, and shed new light on the design of tidal current turbine blade, revealing the importance of bionics in engineering design, having positive influence and guidance on the development, utilization and promotion of ocean. Meanwhile, the research method and data results of this thesis are valuable reference for the further study on the application of bionics in tidal current turbine. |
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