What is a vertical axis wind turbine?

What is a vertical axis wind turbine?

The wind wheel of the vertical axis wind turbine does not adjust its direction with the change of the wind direction. The wind wheel of the vertical axis wind turbine rotates around a vertical axis, and the wind wheel axis is perpendicular to the wind direction. Its advantage is that it can accept wind from any direction, so when the wind direction changes, there is no need to face the wind. Since no steering device is needed, its structural design is simplified. Another advantage of the vertical axis wind turbine is that the gearbox and generator can be installed on the ground for easy maintenance.

The common structures of vertical-axis wind turbines include “S” type wind wheels, Darrieus type wind wheels and rotary wing wind wheels, as shown in Figure 1. The S-type wind wheel is composed of two semi-cylindrical blades with staggered axes. The advantage is that the starting torque is large, but the disadvantage is that the asymmetric airflow is generated around the wind wheel during operation, thereby generating lateral thrust to it. For larger wind turbines, it is more difficult to adopt this type of structure due to the limitation of deflection and safety limit stress.

What is a vertical axis wind turbine?
Figure 1 Vertical axis wind turbine

Darrieus wind turbines use the lift of airfoils to do work and are the main competitors of horizontal axis wind turbines. There are many forms of Darrieux wind turbines, basically straight blades and curved blades. Due to its small wind-receiving area and correspondingly high start-up wind speed, Darieu-type wind turbines have not been vigorously developed.

Theoretically speaking, a rotary-wing wind turbine may not require an upwind device like a horizontal-axis wind turbine, but it also has the problem of speed limitation when it exceeds the working speed. In order to limit the speed, its mechanism must be complicated, and the advantages of its simple structure no longer exist. The wind turbine has not yet entered the practical application stage due to some technical problems that have not yet been resolved.

At present, the H-type wind turbine researched and developed is closely related to the development of science and technology, especially the development of computer technology. Because the design of the H-type vertical axis wind turbine requires a lot of aerodynamic calculations and digital simulation calculations, a manual calculation is used. It takes at least a few years, and the correct result cannot be obtained in one calculation, so the computer is not yet
It is a very developed age, and people simply cannot complete this design concept.

The H-type vertical axis wind turbine adopts the principle of aerodynamics. Aiming at the wind tunnel simulation of vertical axis rotation, the blade adopts the shape of the wing. When the wind wheel rotates, it will not change the efficiency due to deformation; it consists of 4 ~5 blades, the blades are fixed by a quadrangular or pentagonal hub, and a wind wheel is formed by connecting rods connecting the blades. Because this design structure adopts special aerodynamic principles, triangular vector method connection mode and direct drive structure, the force of the wind wheel is mainly concentrated on the hub, so the wind resistance is strong; the characteristics of this design are also Reflected in the impact on the surrounding environment, it has the characteristics of no noise and low electromagnetic interference during operation, which makes the superiority of the H-type vertical axis wind turbine very obvious. The speed of the rotor of the H-type wind turbine increases faster (torque rises fast), and the power generation power that drives the generator increases accordingly, and the power generation curve becomes full.

At present, Japan produces the most H-type wind turbine products, and countries such as the United Kingdom and Canada are also under development. Most products in these countries use parallel connecting rods in the design of wind turbines. This method requires more generator output shafts. It is high, and the structure is relatively complicated, and there are more on-site installation procedures. In addition, from the analysis of mechanics, the greater the power of the H-type wind turbine, the longer the blades, and the longer the distance between the center point of the parallel rod and the center point of the generator shaft, the worse the wind resistance. Therefore, the triangular vector method is adopted. The connection method can make up for some of the above shortcomings.