The Study Of The Aerodynamic Performance Of A Straight-Bladeed Vertical Axis Wind Turbine

The wind turbine is a kind of device to absorb wind energy, which can be classified into two categories, horizontal axis wind turbine (HAWT) and vertical axis wind turbine (VAWT). HAWT has been adopted worldwide for its advanced performance and proven technology, whilst VAWT has attracted more attention for its unique performance. Nowadays, the overall performance of the wind turbine has mainly been obtained by the wind tunnel experiment. However, with the development of modern computer technology, CFD approach has been playing more significant roles in the study of aerodynamic performance of the wind turbine.In this thesis, a series of comparative experiments of a type of straight-bladed wind turbine with asymmetric airfoils DU06-W-200 was conducted in a low-speed small wind tunnel.The wind turbine performance has been investigated in terms of two types of installation method, which are concave-in and concave-out configuration,different stagger angles and various wind speeds. The experimental results show that for the asymmetric airfoils, the concave-out configuration can achieve better performance. There is an optimum angle at which the airfoil performs better if the concave-out configuration is used,and the power coefficient is 22% higher than that of the concave-in configuration when the wind speed was 8m/s; as the wind speed increase to 9m/s,the former is 24% higher than the later.The optimum power coefficient increases with the rise of wind speed.In this thesis, the wind turbine experiments with surface roughness treatment on different positions of the blades was conducted in the wind tunnel in order to study the effect of surface roughness of blade on the performance of VAWT. The measurements show that an abrasive paper with a suitable roughness and width pasted to the trailing edge of the suction side of the blade can effectively improve the power efficient of wind turbine.Moreover, in this thesis, a numerical model was established according to the experiment conditions. Using sliding meshes technology, two-dimensional numerical simulation on unsteady flow of straight-bladed VAWT was carried out with two certain tip speed ratios. The numerical predictions indicate that the numerical results are slightly higher than the experimental value. But the two curves are in good alignment and the trends are basically the same. For the two curves, the optimum tip speed ratios, which are corresponding to the maximum power coefficient, are both around 2.8. The rise of the tip speed ratio, the significant increase of the obstruction of airflow by the wind turbine. More air flow bypass around the rotor rather than go straight through the inside the wind turbine. The stall range at low tip speed ratio is larger than that in high tip speed ratio, which verifies the experimental result.