Design And Research Of The Horizontal Axial Ocean Current Turbine Blade Structure

As traditional energy,such as fossils and coal,decreasing and environmental pollution becoming more and more serious,clean and renewable energy will occupy the leading position in the energy indstry.Current energy is a kind of renewable energy that exists in the form of seawater kinetic energy.It has now become an important research object for the development of renewable energy in the world.Turbine is a mechanical device that converts ocean current energy into rotational mechanical energy.Currently,most turbines in the world can only operate in one direction,while tidal current and tidal motion are two-way.Therefore,two-way turbine can increase the utilization of current energy.The blade is a key component of the turbine and its performance directly affects the performance of the turbine.The airfoil is the basic shape of the blade.In this paper,the design of the two-way turbine was realized by designing the shape of the airfoil.At the end of this paper,the water tank experiment was carried out to verify the feasibility of the two-way turbine.Experiments show that the energy conversion rate of the turbine in the positive direction is the same as the energy conversion rate of the turbine in the opposite direction.The main content of this article is as follows:(1)Based on the collected literature,the paper introduced the classification of marine energy sources and the development of turbine at home and abroad.the paper expounded the design theory of the turbine blade.Take the flow around NACA4408 airfoil as an example to analyze the reasons for the separation of the airfoil boundary layer.Taking the flow around NACA6408 as an example,the airfoil Flow velocity Streamline changes and flow pressure changes after separation of the airfoil boundary layer were analyzed.(2)Three kinds of NACA airfoil with different cambers were selected as the basic airfoils,and then three kinds of Symmetrical airfoil were formed by the reverse docking method.The numerical simulation of the Symmetrical airfoil under different attack-angles was performed to obtain the lift coefficient of the Symmetrical airfoil,the drag coefficient of the Symmetrical airfoil,and the lift to drag ratio of the Symmetrical airfoil.The paper Analyzed the impact of the NACA airfoil's camber on the dynamic characteristics of the Symmetrical airfoil.Taking one of the Symmetrical airfoil as an example,the characteristics of the Flow Velocity Streamline around the Symmetrical airfoil were analyzed at different attack-angles.The results show that the upper airfoil surface arch of the symmetrical airfoil and the the lower airfoil surface arch can make the symmetrical airfoil produce lift,so the symmetrical airfoil can be applied to the design of bi-directional blade.(3)The Symmetrical airfoil was selected as the turbine blade airfoil.Based on the Wilson correction model,the chord length and the torsion angle of the leaf element were solved by using Function in Matlab.The Solidworks software was used to model the blade.The Fluent in ANSYS was used to simulate the blade.the characteristics of flow velocity streamline around the blade were analyzed at different flow velocities.The results show that the blades designed in this paper can make the turbine run stably in the water stream.Using the Static Structural module in ANSYS perform the fluid-structure coupling numerical simulation for the blade.compared the blade deformation characteristics and stress distribution characteristics at different flow velocities.The results show that the maximum deformation and strength of the blade meet the requirements of engineering application When the flow velocity is 0.5m/s~1.8m/s(4)The the ocean current energy conversation device was designed,and in order to increase the flow rate of the water,a duct device was installed outside the turbine.In order to investigate the actual working results of the turbine,a water tank experiment was conducted to measure the output power and energy conversation rate of the turbine at differentflow rates.According to the experimental data,when the flow velocity is1.8m/s,the output power of the turbine reaches the rated power of 40 W,and the energy conversation rate of the turbine reaches the maximum value of 24.3%.Experiments show that the turbine blade designed in this paper can make the turbine work in both directions,and the energy conversion rate of the turbine in the positive direction is the same as the energy conversion rate of the turbine in the opposite direction.