| The development of wind energy in the world is flourishing because it is a kind of absolutely clean and renewable energy. There is considerable wind energy resource in China and the development of wind energy is fully agreed with the durative development strategy. Although there are exciting new development, particularly in the improvement of CFD and theory of aerodynamics, the aerodynamic performance prediction is one of many remained challenges.The performance prediction is necessary to determine the capability of the rotor and the cost of the wind turbine. However the aerodynamics of a wind turbine is extremely complicated, due to the 3-D rotating effects of the blade, effects of an upstream wake for a support structure like tower, complicated environmental effects such as atmospheric turbulence, direction and spatial variations in wind shear, et al.Main contents of this thesis are described as the following:1. Based on the vortex theory, lifting surface method is used to establish wind turbine performance prediction model with rigid cylinder wake model, prescribed wake model and free-wake method. The performance prediction result from the prescribed wake model is better than that from the rigid cylinder wake model.2. Du-Selig stall delay model is used to improve the performance prediction accuracy at the 7~10m/s inflow wind speed. It is found that the large attack angle occurs at the region at the blade mid-span.3. Under unyawed flow condition, the main character of geometry of the tip vortex can be captured with the free-wake model. More accurate performance result of the wind turbine than using prescribed wake model can be acquired.4. Under yawed flow condition, the tip vortex has a skew angle with the wind direction. The attack angle at 57% blade span changes like a... |
