| The Working principle of lift-type vertical axis wind turbine(VAWT) is roughly the same as horizontal axis wind turbine(HAWT). However, compared to the horizontal axis wind turbine, the VAWT with a simple structure have many advantages such as without the need to alignment direction to the wind. But due to the movement process is more complicated, Aerodynamic characteristics belonging to typical large separation Unsteady flow dynamic, the theoretical research of the lift-type VAWT, which contrasted to the HAWT, is relatively lagging behind whether in the domestic or abroad. Recent years, as the development of the research theory of VAWT, such as the flow-tube theory and the Computational fluid dynamics(CFD), More and more people are concerned about the VAWT.The aerodynamic characteristics of the VAWT can be effectively improved by the Installation of guide vanes, baffles and other aid agencies. Howerve, what Indeed complicate the flow characteristics. Which to further reseach and analysis the influence mechanism on the blades will be of great significance for research and development of lift-type vertical axis wind turbine.In this paper, slip grid, RNG k-ε turbulence model, Two-dimensional numerical simulation, and some other technologies about the 2D numerical simulation will be used to study the VAWT. From the micro and macro perspective, we will analyze and study the flow field, pressure distribution, torque output around the blades of VAWT with or without the Symmetrical diversion baffles. And Explore effective ways to improve the overall aerodynamic performance of wind turbines.(1) Firstly, this paper analyzes the Working principle of the straight-blade lift-type VAWT from a purely theoretical view. Physical model, turbulence model, setting boundaries, and some other computing method,which will be used in the process of numerical simulation, are detailed introduced. We systematically analyze the flow field characteristics of the singal blade such as velocity field, pressure distribution, output torque, etc. Of course, which is also be used to the wind wheel.The output torque of the wind wheel, under different speed conditions (tip speed ratio), are researched to explore the best operation condition. Finally, the computing wind speed was determined for the VAWT used in this paper as 150r/min. Refer to the experimental data of the same type of vertical axis wind turbine, we can verify the feasibility of the numerical simulation technology.(2) Then, Numerical simulation will be taken to study the impact of the symmetrical diversion baffle on the VAWT. The velocity field, pressure distribution, surface pressure on the blade, will be detailed comparied and analyzed between blades with baffle or not in the same conditions.(3) The control variable method will be used to looking for the best design of the diversion baffle. Three control variables as the distance away from the rotating field in the horizontal direction, the vertical length and the cut wizard flow angle are set to find the best design. For every control variable, five different solutions are setting to choose a best way. Finally, we decided the best solution on three variables by the analyse of the torque output of blades and the Impeller.Ultimately, We find the best diatance for the distance away from the rotating field in the horizontal direction is between 100-150mm, the best vertical length is between 100-150mm, and the best cut wizard flow angle is between 20°-30°。... |
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