Performance research of VAWT with expandable blades based on savonius turbines

Abstract

In order to improve the wind energy utilization of vertical axis wind turbine (VAWT), this paper presents a new structure of VAWT with expandable blades. The blades of the new turbine are symmetrical airfoil NACA0012 instead of curved blades. The blades of the new structure VAWT have open and folded state. While the blades rotate to the windward side, the blades are open and similar to the curved blades of the S-type turbine. While the blades rotate to the leeward side, the blades are folded and similar to the airfoil of the H-type turbine. In this paper, multistream tube theory was used to analyze the movement of the new type VAWT in the flow field, solve the wind speed influencing factors of the model, establish the theoretical formula of wind energy utilization (CP value) of the new type VAWT. And performance of the wind turbine was simulated and calculated by Matlab. Cp value and self-starting performance of the new type VAWT has greatly improved compared with Savonius type wind turbine. The blade of the new type VAWT is constant section in the vertical direction which can be produced by the costless form of straight blade production. The new type VAWT is not only suitable for medium and large wind farm, but also can be well applied in the areas with relatively poor wind energy resources.