Aerodynamics Simulation for the Spiral-H-Rotor Vertical Axis Wind Turbine

• Main Authors: Chih-yao Chang, 張智堯
• Other Authors: Jiunn-Chi Wu
• Format: Others
• Language: zh-TW
• Published: 2011
• Online Access: http://ndltd.ncl.edu.tw/handle/06525182614975035289

碩士 === 國立中央大學 === 機械工程研究所 === 99 === This numerical study uses computational software FLUENT to analyze aerodynamics characteristic of vertical axis wind turbines (VAWT) with spiral-H-rotor (two capacities: 10 kW and 50 kW). Because of the unique blade shape, three-dimensional numerical simulations must be utilized for understanding the complex aerodynamic pattern. Two analysis are investigated: (1) study the aerodynamic of blade, including various combination of tip speed ratio and inflow wind velocity for this VAWT, in order to realize the characteristic of wind turbines; (2) analyze the relation between thrust coefficient at different azimuthal angle, and display the distribution of local velocity, pressure and vorticity to identify these variables influence on thrust. Results show that when the blades pass through the area of low speed in the center of the rotor or the area of large variation of vorticity, the thrust of blades decrease significantly. In addition, the predicted power coefficient of 10 kW wind turbine (0.356) is close to the value of horizontal axis wind turbine, and the tip speed ratio is recommended to operate around two to three to have maximum power performance. Another analysis is made for a new blade design of 50 kW wind turbine, which is enlarged from the shape of 10 kW with a winglet attached on the blade tip. The winglet arrangement (similar as it on the fixed wing layout) can reduce the tip vortex strength so that to enhance the power output of wind turbine. Predicted maximum power coefficient close to 0.4 and this value decreases as the incoming wind speed decreases. Simulation shows the blade wih winglet increase both the high and low pressure zone near the blade tip, and thus the amount of pressure difference is enlarged. In addition, the strength of vorticity gradient also reduces in the back rotating circular region. This study can provide useful aerodynamic data for the design of new spiral-H-rotor VAWT.