Wind Turbine Component:
Most modem wind turbines used for generating electricity have three blades, although some have two or even one. Three blades have the particular advantage that the polar moment of inertia with respect to yawing is constant. This characteristic contributes to relatively smooth operation even while yawing. Atwo-bladed rotor, however, has a lower moment of inertia when the blades are vertical than when they are horizontal. This 'imbalance' is one of the reasons that most two-bladed wind turbines use a teetering rotor. Using more than three blades could also result in a rotor with a moment of inertia independent of position, but more than three blades are seldom used. This is primarily because of the higher costs that would be associated with the additional blades [Manwell and others, 2002].