Abstract
In order to get rid of the impact of the global financial crisis and actively respond to global climate change, it has become a common choice for global economic development to develop clean energy such as wind energy, improve energy efficiency and reduce greenhouse gas emissions. With the advantages of simple structure, unnecessary facing the wind direction, and unique appearance, the vertical axis wind turbine (VAWT) attracts extensive attention in the field of small and medium wind turbines. The lift-type VAWT exhibits outstanding aerodynamic characteristics at a high tip speed ratio, while the starting characteristics are generally undesirable at a low wind speed; thus, how to improve the starting characteristics of the lift-type VAWT has always been an important issue. In this paper, a lift-drag combined starter (LDCS) suitable for lift-type VAWT was proposed to optimize the starting characteristics of lift-type VAWT. With semi-elliptical drag blades and lift blades equipped on the middle and rear part outside the starter, the structure is characterized by lift-drag combination, weakening the adverse effect of the starter with semi-elliptical drag blades alone on the output performance of the original lift-type VAWT and improving the characteristics of the lift-drag combined VAWT. The static characteristic is one of the important starting characteristics of the wind turbine. The rapid development of computational fluid dynamics has laid a solid material foundation for VAWT. Thus the static characteristics of the LDCS with different numbers of blades were investigated by conducting numerical simulation and wind tunnel tests. The results demonstrated that the static torque coefficient of LDCS increased significantly with the increased incoming wind speed. The average value of the static torque coefficient also increased significantly. This study can provide guidelines for the research of lift-drag combined wind turbines.
Highlights
Environmental protection becomes more extremely important with the development of the economy and society
Wind turbines are divided into two categories, horizontal axis wind turbines (HAWT) and vertical axis wind turbines (VAWT) [5]
The development of the VAWT is relatively lagging compared with the HAWT
Summary
Environmental protection becomes more extremely important with the development of the economy and society. Countries around the world have been vigorously promoting the development of sustainable energy sources [1,2,3,4]. Several representative new energy sources such as wind, nuclear and solar power have been valued and rapidly developed. Wind energy is inexhaustible as one of the clean and pollution-free renewable energy sources. Wind turbines are receiving extensive attention for converting wind energy into mechanical energy. VAWT can receive the wind from any direction without installing wind devices, generators, and drive chains. The straight-bladed vertical axis wind turbine (SB-VAWT) has unique advantages in rural power consumption, street lamps, farmland irrigation, and other fields. In recent years, VAWT has entered people’s field of vision once again and bring a new round of development opportunities
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