Simulate Investigation On Aerodynamic Performance Of Three Straight-Bladed Vertical Axis Wind Turbine

At present, the renewable energy attracts people's more attentions as the environment is becoming worse and supply of energy is getting tenser. As one type of renewable electricity -generation, wind power is not only clean but also more mature in technology and able to be explored in larger scale compared with other types of renewable energy. Therefore, it is being acclaimed and emphasized by most nations. Horizontal axis wind turbine and vertical axis wind turbine (VAWT) are two basic forms of wind turbine. Although horizontal-axis wind turbine is widely in use abroad, researchers of many countries pay more and more attention to the vertical- axis wind turbine for its excellence performance. And now, with the development of modern computer technology and simulation method of turbulence, CFD is playing more significant roles in studying aerodynamic performance. Based on this, the representative wind turbine NACA0015 airfoil were selected as the research objects in the paper and the steady and unsteady flows around them were simulated.Firstly,the NACA0015 airfoil were selected, and the steady flows around the airfoil were simulated, and the turbulence was treated separately by using Spalart-Allmaras model and k-ωSST model. The difference in computed results between two turbulence models were compared, and come to the aerodynamic characteristics of the airfoil, base on this ,the more appropriate turbulence model Spalart-Allmaras model were selected to simulate the airfoil with Gurney trailing edge of different height, then compared with the original NACA0015 airfoil, the simulation results show that adding the Gurney flap were able to raise the maximum lift coefficient and efficient airfoil lift coefficient, and also the increasing effectiveness is closely associated with height. Comparison of outcome that when the height of Gurney flat is 2% chord, can achieve the best lift-drag ratio under steady-state output.Then numerical simulation on unsteady rotated flow of a straight-blade vertical VAWT is done base on sliding meshes by means of the software Fluent. The wake velocity and the variation of velocity at the special cross-section are obtained. The conclusion can be made that the numerical simulation on unsteady rotated flow of a straight-blade VAWT based on sliding meshes can represent its flow field. After that, Three series of eight modification tails of NACA0015 airfoil were simulated, the computed results are compared with the original NACA0015 airfoil, the results show that 2% chord of the internal modifications and T-type forms are better than the NACA0015 airfoil, especially under a given tip speed ratio of 3 the VAWT power can be greatly improved, however the applicable range is little, and as the tip speed ratio to 3.5 after, modified form of any tail have the trend of increasing resistance during operation, Obviously, further study is needed here. At last, the full paper were summarized and the future research were discussed which would lay foundations for the further research.