Wind turbines are energy converters
. Independent of their application, type or detailed design all wind turbines have in common that they convert the kinetic energy of the flowing air mass into mechanical energy of rotation. As already discussed in chapter 2, two
are suitable for this purpose, the lift and the drag, see Fig. 3-1. Drag driven rotors reach only, as mentioned, moderate power coefficients and are of no major importance to the technical applications, apart from the anemometers.