Generally, a wind turbine includes a tower, a nacelle mounted on the tower, and a rotor coupled to the nacelle. The rotor typically includes a rotatable hub and a plurality of rotor blades coupled to and extending outwardly from the hub. Each rotor blade may be spaced about the hub so as to facilitate rotating the rotor to enable kinetic energy to be transferred from the wind into usable mechanical energy, and subsequently, electrical energy.
Advances in the wind turbine industry are resulting in increasingly larger wind turbines. Of particular concern due to these increasing sizes, however, is the weight of the wind turbine and components thereof. A particular concern is the weight of the rotor, which includes a hub and one or more rotor blades mounted to the hub. During operation of the wind turbine, the hub may be subjected to forces resulting from wind acting on the rotor blades and forces resulting from loads due to the rotation of the hub. The hub must be stiff enough so that these forces do not cause high deformations. In particular within the flanges for mounting the rotor blades to the hub, the hub must be designed rather stiff so that deformation or distortion, such as ovalization can be prevented, which in turn would affect the proper function and possibly damage the rotor blade bearings and pitch drives.
One example of an improved hub that improves or maintains the necessary stiffness while reducing weight is found in U.S. Pat. No. 7,244,102, directed to a reinforced hub. The hub includes a stiffening web extending within a blade flange area defined by a blade flange. The stiffening web can be oriented to extend within the flange area generally parallel to a rotation axis about which the hub rotates during operation, or at any suitable angle to the rotation axis. However, a side profile of the stiffening web of U.S. Pat. No. 7,244,102, or of a plane defined by the stiffening web that extends from a first end to a second end of the hub, is always parallel to the rotation axis. As such, a certain amount of material is required to connect the stiffening web to the flange and hub.
Accordingly, an improved hub for a rotor of a wind turbine is desired in the art. For example, a hub that includes stiffening features to maintain desired stiffness characteristics while reducing the material and associated weight required to connect the stiffening features to the flange and hub would be advantageous.