Introduction To Vertical Axis Wind Turbine

Vertical axis wind turbine does not need to face the wind when the wind direction changes, which is a big advantage over horizontal axis wind turbine. It not only simplifies the structure design, but also reduces the gyroscopic force when the wind wheel faces the wind.

Classification

Although there are many kinds of wind turbines, they can be divided into two categories:

(1) horizontal axis wind turbines, whose rotation axis is parallel to the wind direction;

(2) Vertical axis wind turbine, wind wheel rotation axis is perpendicular to the ground or the direction of the air flow.

There are several types of vertical axis wind turbines that use resistance to spin. There are wind turbines made of plates and cups, which are pure resistance devices; The S-shaped windmill has some lift, but is mainly a drag device. These devices have a large starting torque, but low tip ratio, and provide low power output at a given wheel size, weight and cost.

The Darieux wind wheel was invented in the 1830s by the French G.J. M. Darieux. In the 1970s, the Canadian National Academy of Sciences did a lot of research on this and was the main contender for horizontal axis wind turbines. A Darieux wind turbine is a lift device in which the profile of the curved blade is the airfoil. It has a low starting torque, but can have a high tip ratio and a high power output for a given wind turbine weight and cost. There are many types of Dariet wind turbines in the world, such as Φ, Delta, Y and H. These turbines can be designed with single, double, triple or multiple blades.

Other forms of vertical-axis wind turbines include the Magnus effect wind turbine, which consists of spinning cylinders. When it operates in an air stream, the displacement force generated by the Magnus effect is proportional to the wind speed. Some vertical axis wind turbines use pipes or vortex generators to change the horizontal air flow into the vertical air flow through a casing or diffuser to increase the speed, and sometimes use solar energy or burn some kind of fuel to change the horizontal air flow into the vertical direction.

Development

Vertical axis wind turbine - making wind power building integration possible 

Wind power, like solar power, was originally developed as a solution to emergency power and remote areas, so its initial development was slow. 

In the 1920s and 1930s, the energy shortage brought about by the global economic crisis made experts around the world think of the feasibility of wind power generation as a supplementary energy. After World War II, many countries began to study wind turbines. Due to the poor technology, high start-up speed and loud noise, wind turbines had to be placed in places with few people or strong winds. Equipment is also to the development of large wind turbines, specially built large wind farms, because of the characteristics of horizontal axis wind turbines, small wind power generation has not been well developed in a long time.

All developed countries are vigorously developing the new energy industry, and solar energy has always been the first choice for the commercialization of new energy, because the location of solar energy is more flexible, does not produce noise, and can be integrated with the building design. Compared with solar energy, wind power generation has obvious cost advantages. How to make wind power generation and building integrated design and set small wind turbines around buildings without affecting people's quality of life has become the focus of some countries in Europe and the United States!

Vertical axis wind turbine from the classification, mainly divided into resistance and lift type. The drag type vertical axis wind turbine mainly uses the drag generated by the air flowing through the blade as the driving force, while the lift type uses the lift generated by the air flowing through the blade as the driving force. In the process of blade rotation, the resistance decreases sharply with the increase of rotational speed, while the lift force increases. Therefore, the efficiency of lift type vertical axis wind turbine is much higher than that of resistance type.