Читать книгу Wind Energy Handbook - Michael Barton Graham - Страница 56

The manner in which the extracted energy is converted into usable energy depends upon the particular turbine design. The most common type of wind energy converter, the horizontal axis wind turbine or HAWT, employs a rotor with a number of blades rotating with an angular velocity Ω about an axis normal to the rotor plane and parallel to the wind direction. The blades sweep out a disc and by virtue of their aerodynamic design develop a pressure difference across the disc, which, as discussed in the previous section, is responsible for the loss of axial momentum in the wake. Associated with the loss of axial momentum is a loss of energy that can be collected by, say, an electrical generator attached to the rotor shaft. As well as a thrust, the rotor experiences a torque in the direction of rotation that will oppose the torque that the generator exerts. The work done by the aerodynamic torque on the generator is converted into electrical energy. The required aerodynamic design of the rotor blades to provide a torque as well as a thrust is discussed in Section 3.5.