Study On The Key Technologies Of Small Tidal Current Energy Generation

Tidal current energy generation is an important way to solve the problems of world energy need, environmental protection and the social sustainable development, as one of the application trends, small scaled practical power generation type not only has a widely application prospects, but also provide a novel solution for energy supply of ocean observation instruments. Pointing at the power limited issue of small device, the research on the design and analysis of the small tidal current energy generation prototype was conducted in this article,focusing on the design of the tidal current turbine which mainly decides the performance of the device and trying to solve the key technical problems such as the design parameters determination, selection and characteristics calculation of airfoil, design and performance analysis of small turbine,flow-structure interaction analysis of turbine, etc. And finally,the experiment was conducted to validate the performance of the designed prototype.Based on the sea condition of our country, both theory and numerical simulation method were used to conduct the research of the overall design parameters of the prototype, analyzing and determining the key design parameters such as design velocity, turbine diameter, number of blades, optimally design tip speed ratio, etc. And reference guidelines of generator selection and size design of sealed box were also provided.Pointing at the current status that NACA airfoils, which has poorly stall characteristics, are used for all of the fixed-pitch turbine design in our country, four airfoils including three ones(S809,FFA-W3-241,RIS?-A1-211) which were designed for fixed pitch control turbine and NACA63-418 airfoil were selected for comparative study and airfoil characteristics calculation. At the same, the applicability of numerical simulation method and extrapolation algorithms of airfoil characteristics calculation was studied.Based on current design theory, four turbines’ hydrodynamic shapes were designed using the blade element momentum theory. Also, hydrodynamics performance were analyzed with the results showed that: the output characteristics of the turbine with RIS?-A1-21 airfoil was best meet the design requirements, with the power reduction occurred earlier, the maximum output power is small and can reach steady output power state quickly with the stable output power close to rated output power.The structural design of the prototype was conducted, and strength analysis for the key components of prototype, the blade, was carried out using flow-structure interaction analysis technique. The CFD analysis provided hydrodynamic load and identified extreme load conditions for structural analysis, and also offered the output characteristics, cavitation characteristics and flow field information of different calculation condition. Strength and stiffness analysis and verification of structural was conducted by static structure analysis, meanwhile the sensitivity of grid for introduced fluid load was also studied. More, the natural frequencies and mode shapes were calculated through model analysis.In order to verify the performance of designed prototype, experimental research were carried out, and the comparison among experimental, blade element momentum theory and CFD simulation results showed that under the tested tip speed ratio, the experimental results were in good agreement with blade element momentum and CFD results.