Energy Extraction Performance Analysis Of Oscillating Hydrofoil Based On Blockage Effect

Nowadays,most of the research on tidal turbines is in the simulation stage.This paper analyzes the performance of oscillating hydrofoil energy extraction in different blockage environments,and explores the energy extraction performance of the different maximum pitch angle and the different reduced frequency in different blockage environments.This paper performs three-dimensional(3D)simulation of an oscillating hydrofoil because the researches in this paper involve the three-dimensional space of hydrofoil movement.The researches are as follows:(1)In order to explore the law of the oscillating hydrofoil motion,the method of the oscillating hydrofoil motion is being studied.And the coupling of hydrofoil heave and pitch motion is analyzed.(2)In order to study the effect of different blocking environments on the energy extraction of oscillating hydrofoil,this paper changes the blockage environment of the hydrofoil by changing the size of the flow field and keeping the oscillating hydrofoil unchanged.The software ICEM is used to meshing the flow field of the oscillating hydrofoil and the software FLUENT is used for hydrodynamic simulation of the oscillating hydrofoil in order to verify the accuracy of the meshing and simulation results.The energy extraction performance of different aspect ratios oscillating hydrofoil is analyzed,and the aspect ratio of hydrofoil for power generation is explored.(3)In order to study the energy extraction performance of oscillating hydrofoils in different blockage environments,hydrodynamic simulations of oscillating hydrofoil were performed.It is used to study the effect of different blockage on hydrofoil energy extraction performance.And the situation of different flow field under the same blockage is further analyzed to study the effect of different flow fields on hydrofoil energy extraction performance.Finally,blockage corrections are performed to predict the energy extraction performance of the oscillating hydrofoil in any blockage environment.(4)In order to further analyze the influence mechanism of blockage on hydrofoil energy extraction,the relationship between the hydrofoil surface attachment vortex and the hydrofoil surface pressure distribution,the relationship between the hydrofoil surface attachment vortex and lift under different blockage environments are analyzed.The vorticity is quantified to quantitatively represent the change of vorticity,and the influence of different blockage environments on the vortex attached to the hydrofoil surface is obtained.(5)In order to obtain the highest energy when oscillating hydrofoil tidal turbines are arranged in different blockage environments,the maximum pitch angle and the reduced frequency of hydrofoils in different blockage environments is studied.The optimum pitching angle and reduced frequency for this blockage situation were obtained,which laid a foundation for the layout of the oscillating turbine in the future.