The Horizontal Axis Wind Turbine Instruction.
The rotor of the horizontal axis wind turbine rotates around a horizontal axis, and during working, the rotating plane is vertical to the wind direction. The blades of the wind turbine are installed perpendicularly to the rotating axis, and form a certain angel.
The number of the blades depends on the function of the wind turbine. The wind turbine with more blades is often called as the Low-speed Wind Turbine, and when it works at low speed, it will gain a high ratio of utilization of the wind and a high torque. The wind turbine with fewer blades is often named as the High-speed Wind Turbine, and when it works at high speed, it will gain a high ratio of utilization of the wind, but the starting wind speed should be high. Because of its fewer blades, in the same condition of power, the rotor of the Low-speed is much lighter, so it is suitable to generate power.
Depending on the different relative position of the rotor and tower, the horizontal axis wind turbine can be divided into the Upwind Wind Turbine and the Downwind Wind Turbine. The rotor rotates before the tower facing the wind, and this kind is known as the Upwind Wind Turbine, while if the rotor is installed on the tower following the wind, this kind can be addressed as the Downwind Wind Turbine. The Upwind Wind Turbine must have a certain kind of steering installation to ensure the rotor to face the wind during working, while the Downwind Wind Turbine can face the wind automatically to save the trouble of installing of the steering device. However, with regards to the Downwind Wind Turbine, because a part of wind blows to the blades across the tower, the tower will disturb the gas flow which should go across the blades. In this way, it will cause the so-called Tower Shadow Effect, and the efficiency will be also be decreased.
The horizontal axis wind turbine can also be divided into the Lift-type Wind Turbine and the Resistance-type Wind Turbine, and the former has a high rotating speed, while the latter has a low rotating speed. As to generate power with wind, the Lift-type Wind Turbine is more frequently adopted. Most of the horizontal axis has the steering device, and can rotate with the wind. To the small-sized wind turbine, the steering device employs the tail vane, while to the large-sized wind turbine, it often adopts the gear consisting of wind sensors and
There are many types of the horizontal axis wind turbine: some with rotor with reversal blades, some with several rotors installed on one tower to reduce the cost of tower on the condition of a certain output power, some with tapered hood to ensure that when the gas flow goes through the horizontal axis in a centralized or decentralized way in order to increase or decrease the speed, and some with whirlpool shaped by the horizontal axis wind turbine around the rotor to centralize the wind and raise the speed of the gas flow.
The technology of the horizontal axis wind turbine is more mature, and it is easy to produce high-power wind turbines, but the structure is complicated. The ratio of the utilization of the wind power is not so high as the vertical axis wind turbines.