The Vertical Axis Wind Turbine Instruction.
The rotor of the vertical axis wind turbine rotates around a vertical axis. The main advantage of it is that it can receive wind from any direction, so when the wind changes, the wind turbine of this kind has no need to initiate the steering device to deviate the rotor to face the wind. Because there is no need of the steering device, the structure of the vertical wind turbine is simplified. Another merit of this kind is that the gear box and the generator can be installed on the ground. To the maintenance personnel who has to repair and maintain a horizontal axis wind turbine which is about more than ten meters up the ground in the strong gust, it must be a highly praised merit.
The vertical axis wind turbine is mainly consisted of two types. The first type uses aerodynamic resistance of the wind, and the most typical structure is S-typed Rotor, which consists of two semi-cylindrical blades whose axes are staggered. The virtue of this type is high starting torque, but the shortcoming is the asymmetrical gas flow around the rotor, which forms lateral thrust. As for the relatively large-sized wind turbine, for the deflection and safety limitation, it is quite difficult to employ this structure. The ratio often utilization of the wind is lower than that of the High-speed Vertical axis wind turbine or Horizontal axis wind turbine, and the output of power is lower in a certain circumstance of the size of the rotor, weight and cost, so it lacks competition if it is used to generate power.
The second type applies the lift of the airfoil to work, and the most typical type is the Darrieus-typed Wind Turbine, which was invented by a French man named Darrieus in 1925. it has may different models, such as the Φ structure，Δ structure，Y structure and H structure and so on. But as its wind area is small and accordingly the starting wind speed is high, it has not been taken into practice in a large scale.
Nowadays, the popular type is the H structure. It employs the air-hole mechanics. According to the air-hole simulation experiment, the blades adopt the airfoil shape of the blade of the airplane, and when the rotor rotates, it will not change the efficiency due to the deformation. It includes 4 or 5 blades in perpendicular position, and are fixed and connected to the blades by the quadrangular or quinquangular wheel hub. During working, the rotor drives the generator to send power to the controller, and output the required power to the electrical equipment.
Due to the reason that the gas flow of the vertical axis is more complex than the horizontal axis, vertical axis wind turbines started late, and the theory is not yet mature. But the structure is simple. The wind can be used at a higher efficiency, without complex phase modulation institutions. It can start smoothly with low wind speed and low noise. It can be said as a direction of development of the wind turbines.