Tidal Turbine's FSI Analysis Based On BEM Theory

With the economic development of human society, the traditional fossil energy is increasingly exhausted ,accompanied by serious environmental problems. As a kind of clean and renewable energy, tidal current energy plays an important role in the adjustment of energy structure. Horizontal axis tidal turbines (HATT), a kind of effective power energy conversion device, plays a decisive role in the development and utilization of tidal energy.At present, fluid-structure interaction (FSI) method , based on CFD and CSD , is usually adopted to analyze tidal turbine, which is time-consuming in modeling and owns a huge number of grids, leads to long computing time and needs for high-performance computer.Thus, establishing a fast and efficient FSI method is important significance on the development of tidal turbines.As an efficient empirical model based on blade element momentum theory has been used in the turbine hydrodynamic performance calculation and verified. For elongated body,beam theory achieves a perfect match, and simplifies calculation of the results and has some reference value, combining of these two theories quickly and efficiently computing.Firstly, based on blade element momentum theory, with tip and hub correction,three-dimensional correction, yaw correction complementary set up the hydrodynamic model of HATT. Through the calculation get the power output and thrust, compared the results with the references.Secondly, based on the 2 nodes and 12 degrees of freedom Euler-Bernoulli beam element establish a finite element model, use Newmark-beta method as a numerical method to solve the structural dynamics model, through the calculation of structure dynamics and static mechanics testing method and program.Finally, feedback the speed and force established fluid structure model of HATT's blade, achieved the computing of one-way coupling, two-way coupling, pitch, yaw and other functions. Using this method calculate the turbine performance and structural dynamic response under different speed,analyzed the impact of the turbine blade vibration performance, and yaw effect for HATT's performance under flow-solid coupling condition,and finally by adjusting the stiffness of the blade examine the affect of structure to the output.The results of fluid-structure coupling based on BEM show that it s affect the output characteristics and the structure response of the HATT blade. Results of this study to improve the efficiency of the analysis of turbine complex environment of great significance,especially in the early stages of turbine design.