| A novel tidal current energy extracting technology with oscillating hydrofoil that imitating the foil/tail of the aquatic animals is explored,considering the bionic oscillating hydrofoil hydroturbine have many advantages which include high efficiency,low noise and harmless effects to aquatic animals compared to traditional rotary hydroturbine.Base on the analyzing of kinematics and hydrodynamic model for oscillating hydrofoil,in the case of turbulent flow,the relation between the oscillating hydrofoil tidal stream energy extracting efficiency and the kinematic parameters of oscillating hydrofoil,effect of the oscillating hydrofoil shape on the tidal current energy extracting efficiency are carried out.The interaction between the hydrofoil surface attached vortex to the pressure on the hydrofoil surface to the tidal current energy extracting efficiency are explored.The oscillating hydrofoil tidal current energy extracting prototype is built.Testing with this prototype in the water circulating tunnel is carried out to verify the relations of energy extracting power and efficiency to the kinematic parameters,hydrofoil shape parameters.This project tries to explore a novel tidal current energy extracting technology for high efficiency and environment friendly tidal current energy development.(1)Based on the comprehensive research status analysis of oscillating hydrofoil energy extraction device and the kinematic parameters at home and abroad,the movement characteristics and the shape parameters of oscillating hydrofoil are analyzed,and combined with the hydrodynamic characteristics,a two-dimensional oscillating hydrofoil motion model is established.The principle of hydrofoil motion and the relationship among hydrodynamic parameters of oscillating hydrofoil are determined.The parameters to measure the characteristics of oscillating hydrofoil energy extraction efficiency and power are given.A whole scheme design for the oscillating hydrofoil energy extraction device was achieved.(2)Design multi-purpose prototype.The length and initial position of the heaving and pitching crank rocker mechanism are determined with optimal design method,and the reliability of optimization results are proved through dynamics simulation.On this foundation,the mechanical structure of each transmission part is designed.The frame-type device stand is built by the standard aluminlum alloy sections.The static analysis shows that the lever of crank rocker mechanism and the device stand meet the static strength and stiffness requirements.The mechanical structure is well designed,the device is carefully installed and debugged,finally the oscillating hydrofoil tidal current energy extracting prototype is built.(3)In order to obtain the impact mechanism of the oscillating hydrofoil shape on the tidal current energy extracting efficiency,movement characteristics of oscillating hydrofoil in different shapes are analyzed by Fluent software.By explored the relation between the oscillating hydrofoil tidal stream energy extracting efficiency and the kinematic parameters of oscillating hydrofoil,effect of the oscillating hydrofoil shape on the tidal current energy extracting efficiency,in the case of turbulent flow,revealed the tidal current energy extracting efficiency mechanism which impact by the dynamic behavior of the rectanglur plate and the NACA airfoil surface attached vortex.Summarize the relationsand features of energy extracting performance to the kinematic parameters,hydrofoil shape parameters.(4)Experimental platform based on the tidal current energy extraction prototype is built in the water circulating tunnel.For the rectanglur plate and the NACA airfoil,a series of experiments are performed,the experiment of energy extraction efficiency with different reduced frequencies at constant flow velocity,the experiment of the maximum power changes with the flow velocity at different flow rates and the experiment of the mechanical losses estimates under hydrofoil removal conditions.Analyze and compare the numerical simulation results,experimental results and he mechanical losses estimates,verify the relations of energy extracting power and efficiency to the kinematic parameters,hydrofoil shape parameters.Validate the analysis of hydrofoil performance and the calculation results are reasonable and correct. |
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