Angled blade root   

FIELD OF THE INVENTION

The present subject matter relates generally to wind turbines and, more particularly, to an angled blade root for a wind turbine rotor blade.

BACKGROUND OF THE INVENTION

Wind power is considered one of the cleanest, most environmentally friendly energy sources presently available, and wind turbines have gained increased attention in this regard. A modern wind turbine typically includes a tower, generator, gearbox, nacelle, and one or more rotor blades. The rotor blades capture kinetic energy from the wind using known airfoil principles and transmit the kinetic energy through rotational energy to turn a shaft coupling the rotor blades to a gearbox, or if a gearbox is not used, directly to the generator. The generator then converts the mechanical energy to electrical energy that may be deployed to a utility grid.

To ensure that wind power remains a viable energy source, efforts have been made to increase energy outputs by modifying the size and capacity of wind turbines. One such modification has been to increase the length and surface area of the rotor blades. However, the magnitude of deflection forces and loading of a rotor blade is generally a function of blade length, along with wind speed, turbine operating states, blade stiffness, and other variables. This increased loading not only produces fatigue on the rotor blades and other wind turbine components but may also increase the risk of a sudden catastrophic failure of the rotor blades, for example, when excess loading causes deflection of a blade resulting in a tower strike.

Accordingly, a rotor blade configuration that allows for the use of longer rotor blades without increasing the likelihood of a tower strike would be welcomed in the technology.

Aspects and advantages of the invention will be set forth in part in the following description, or may be obvious from the description, or may be learned through practice of the invention.

In one aspect, the present subject matter discloses a rotor blade for a wind turbine. The rotor blade may generally include a blade root defining a planar surface, a blade tip and a body extending between the blade root and the blade tip. The body may define a longitudinal axis and may include a pressure side and a suction side extending between a leading edge and a trailing edge. Additionally, an angle may be defined between the planar surface and a reference plane extending perpendicular to the longitudinal axis. The angle may be greater than 0 degrees and less than about 10 degrees.

In another aspect, the present subject matter discloses a wind turbine. The wind turbine may include a plurality of rotor blades. Each rotor blade may include a blade root defining a planar surface, a blade tip and a body extending between the blade root and the blade tip. The body may define a longitudinal axis and may include a pressure side and a suction side extending between a leading edge and a trailing edge. Additionally, an angle may be defined between the planar surface and a reference plane extending perpendicular to the longitudinal axis. The angle may be greater than 0 degrees and less than about 10 degrees.

In another aspect, the present subject matter discloses a blade root for a wind turbine rotor blade. The blade root may generally comprise a substantially cylindrically shaped member extending lengthwise along a longitudinal axis and defining a planar end surface. Additionally, an angle may be defined between the planar end surface and a reference plane extending perpendicular to the longitudinal axis. The angle may be greater than 0 degrees and less than about 10 degrees.

These and other features, aspects and advantages of the present invention will become better understood with reference to the following description and appended claims. The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

A full and enabling disclosure of the present invention, including the best mode thereof, directed to one of ordinary skill in the art, is set forth in the specification, which makes reference to the appended figures, in which:

FIG. 1 illustrates a perspective view of one embodiment of a wind turbine;

FIG. 2 illustrates a perspective view of one embodiment a rotor blade in accordance with aspects of the present subject matter;

FIG. 3 illustrates a side view of an outboard portion of the rotor blade shown FIG. 2, particularly illustrating a blade root of the rotor blade;

FIG. 4 illustrates a top view of the blade root shown in FIG. 3; and,

FIG. 5 illustrates a partial side view of a wind turbine having the rotor blade shown in FIGS. 2-4 installed thereon.

DETAILED DESCRIPTION

Reference now will be made in detail to embodiments of the invention, one or more examples of which are illustrated in the drawings. Each example is provided by way of explanation of the invention, not limitation of the invention. In fact, it will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the scope or spirit of the invention. For instance, features illustrated or described as part of one embodiment can be used with another embodiment to yield a still further embodiment. Thus, it is intended that the present invention covers such modifications and variations as come within the scope of the appended claims and their equivalents.

In general, the present subject matter is directed to a rotor blade for a wind turbine having an angled blade root. In particular, the blade root of the rotor blade may define a planar end surface oriented at an angle relative to the longitudinal axis of the rotor blade. Accordingly, when the rotor blade is installed onto a wind turbine hub, an increase in the amount of tower clearance defined between the rotor blade and the wind turbine tower may be achieved. Such increased tower clearance may allow for longer and/or lighter rotor blades to be utilized on a wind turbine, thereby increasing the efficiency and/or output of the wind turbine and/or decreasing the costs required to manufacture each rotor blade.

Referring now to the drawings, FIG. 1 illustrates perspective view of one embodiment of a wind turbine 10. As shown, the wind turbine 10 includes a tower 12 extending from a support surface 14, a nacelle 16 mounted on the tower 12, and a rotor 18 coupled to the nacelle 16. The rotor 18 includes a rotatable hub 20 and at least one rotor blade 22 coupled to and extending outwardly from the hub 20. For example, in the illustrated embodiment, the rotor 18 includes three rotor blades 22. However, in an alternative embodiment, the rotor 18 may include more or less than three rotor blades 22. Each rotor blade 22 may be spaced about the hub 20 to facilitate rotating the rotor 18 to enable kinetic energy to be transferred from the wind into usable mechanical energy, and subsequently, electrical energy. For instance, the hub 20 may be rotatably coupled to an electric generator (not shown) positioned within the nacelle 16 to permit electrical energy to be produced.

Referring now to FIGS. 2-4, one embodiment of a rotor blade 100 having an angled blade root 102 is illustrated in accordance with aspects of the present subject matter. In particular, FIG. 2 illustrates a perspective view of the rotor blade 100. FIG. 3 illustrates a side view of an inboard portion of the rotor blade 100 shown in FIG. 2, particularly illustrating the blade root 102 of the rotor blade 100. Additionally, FIG. 4 illustrates a top view of the blade root 102 shown in FIG. 3.

As shown, the rotor blade 100 generally includes a blade root 102 and a blade tip 104 disposed opposite the blade root 102. A body 106 of the rotor blade 100 extends lengthwise along a longitudinal axis 108 between the blade root 102 and the blade tip 104 and generally serves as the outer shell of the rotor blade 100. As is generally understood, the body 106 may define an aerodynamic profile to enable the rotor blade 100 to capture kinetic energy from the wind using known aerodynamic principles. Thus, the body 106 may generally include a pressure side 110 and a suction side 112 extending between a leading edge 114 and a trailing edge 116. Additionally, the rotor blade 100 may have a span 118 defining the total length of the blade 100 between the blade root 102 and the blade tip 104 and a chord 120 defining the total length of the body 106 between the leading edge 114 and the trailing edge 116. As is generally understood, the chord 120 may vary in length with respect to the span 118 as the rotor blade 100 extends from the blade root 102 to the blade tip 104. It should be readily appreciated that the longitudinal axis 108 of the rotor blade 100 may extend parallel to the span 118.

As indicated above, the body 106 of the rotor blade 100 may generally define an aerodynamic profile or shape. For example, in several embodiments, the body 106 may define an airfoil shaped cross-section, such as by defining a symmetrical or cambered airfoil-shaped cross-section. In addition, the rotor blade 100 may also be aeroelastically tailored. Aeroelastic tailoring of the rotor blade 100 may entail bending of the blade 100 in a generally chordwise direction and/or in a generally spanwise direction. The chordwise direction generally corresponds to a direction parallel to the chord 120 of the rotor blade 100. The spanwise direction generally corresponds to a direction parallel to the span 118 or longitudinal axis 108 of the rotor blade 100. Aeroelastic tailoring may further entail twisting of the rotor blade 100, such as twisting the blade 100 in a generally chordwise and/or spanwise direction.

Referring particularly to FIGS. 3 and 4, the blade root 102 of the rotor blade 100 may generally comprise a substantially cylindrically shaped member extending outwardly from the aerodynamically shaped body 106 of the rotor blade 100. For example, as shown in FIG. 3, the blade root 102 may extend from the body 106 along a longitudinal axis 122 oriented parallel to and/or coaxial with the longitudinal axis 108 of the rotor blade 100. In general, the blade root 102 may be configured to be mounted or otherwise attached to the hub 20 of a wind turbine 10. For example, as shown in FIG. 4, a plurality of stud or bolt holes 124 may be defined through a planar end surface 126 of the blade root 102 for receiving a corresponding number of studs or bolts (not shown). As is generally understood, the studs or bolts may be used to attach the blade root 102 to a pitch bearing 128 (FIG. 5) disposed within and/or coupled to the hub 20. For instance, the blade root 102 may be configured to be rigidly attached to the pitch bearing 128 such that the end surface 126 contacts against and extends parallel to a corresponding surface of the pitch bearing 128. However, it should be appreciated by those of ordinary skill in the art that the blade root 102 may be attached to the hub 20 using any other suitable means and/or attachment method known in the art.

It should be appreciated that, several embodiments, the blade root 102 may be formed integrally with the body 106 of the rotor blade 100. Alternatively, the blade root 102 may comprise a separate component configured to be separately attached to the body 106.

As particularly shown in FIG. 3, in accordance with several embodiments of the present subject matter, the end surface 126 of the blade root 102 may be oriented at an at an angle 130 relative to the rotor blade 100. Specifically, the end surface 126 may be configured such that an angle 130 is defined between the end surface 126 and a reference plane 132 extending perpendicular to the longitudinal axis 108 of the rotor blade 100 and/or the longitudinal axis 122 of the blade root 102. As such, when the blade root 102 is attached to the hub 20 of a wind turbine 10, the longitudinal axis 108, 122 of the rotor blade 100 and/or the blade root 102 may be oriented at a non-perpendicular angle relative to the interface defined between the end surface 126 and the pitch bearing 128. It should be appreciated that, as used herein, the term “reference plane” corresponds to an imaginary plane defined perpendicular to the longitudinal axis 108, 122 of the rotor blade 100 and/or the blade root 102 and extending parallel to the chord 120 of the rotor blade 100.

In general, the angle 130 defined between the end surface 126 of the blade root 102 and the reference plane 132 may comprise any suitable angle greater than 0 degrees. However, in several embodiments, the angle 130 may range from greater than 0 degrees to less than about 10 degrees, such as from about 0.5 degrees to about 5 degrees or from about 0.5 degrees to about 3 degrees or from about 0.5 degrees to about 2 degrees or from about 1 degree to about 2 degrees and all other subranges therebetween.

In several embodiments, the planer end surface 126 may be defined in the blade root 102 such that the end surface 126 is angled towards the pressure side 110 of the rotor blade 100. For example, as shown in FIG. 3, the plane defined by the end surface 126 may be angled inwardly between a first edge 134 defined on the suction side 112 of the rotor blade 100 and a second edge 136 defined on the pressure side 110 of the rotor blade 100, with the first edge 134 generally corresponding to the point on the end surface 126 disposed furthest away from the blade tip 104 of the rotor blade 100 and the second edge 136 generally corresponding to the point on the end surface 126 disposed closest to the blade tip 104. As such, when the rotor blade 100 is installed on a wind turbine hub 20, the rotor blade 100 may be angled away from the tower 12. Moreover, in one embodiment, the end surface 126 may be defined in the blade root 102 such a centerline 138 defined halfway between the first and second edges 134, 136 is generally aligned with and extends parallel to the chord 120 of the rotor blade 100. Accordingly, the tower clearance defined between the rotor blade 100 and the tower 12 may be maximized when the blade 100 is pitched to its power position during operation (i.e., a position at which the pressure side 110 of the rotor blade 100 faces directly into the wind).

It should be appreciated that the end surface 126 of the blade root 102 may be formed using any suitable manufacturing method and/or means known in the art. For instance, in several embodiments, the blade root 102 may be initially formed having an end surface oriented substantially perpendicularly to the longitudinal axis 108, 122 of the rotor blade 100 and/or the blade root 102 (i.e., substantially parallel to the reference plane 132). In such embodiment, the angled end surface 126 may be formed by cutting, grinding or otherwise removing portions of the blade root 102 using any suitable cutting, grinding and/or machining equipment. Alternatively, the blade root 102 may be initially formed having the angled end surface 126.

Referring now to FIG. 5, there is illustrated one embodiment of the rotor blade 100 shown in FIGS. 2-4 installed on a wind turbine hub 20. Specifically, FIG. 5 illustrates the difference in tower clearance 144, 146 achieved through the use of the disclosed rotor blade 100 as compared to a conventional rotor blade 22 (indicated by dashed lines). As shown, when the blade root 102 of the disclosed rotor blade 100 is secured to the hub 20 (e.g., by securing the end surface 126 to a portion of the pitch bearing 128), the interface defined between the end surface 126 and the hub 20 is oriented at a non-perpendicular angle relative to the longitudinal axis 108 of the rotor blade 100. Thus, due to the angled interface, the rotor blade 100 may be configured to extend outwardly away from the tower 12. In contrast, when the blade root 140 of a conventional rotor blade 22 is secured to the hub 20, the interface defined between the rotor blade 22 and the hub 20 is oriented perpendicular to the longitudinal axis 142 of the blade 22 and, thus, the rotor blade 22 extends generally parallel to the tower 12. Accordingly, the tower clearance 144 defined between the disclosed rotor blade 100 and the tower 12 may be significantly higher than the tower clearance 146 defined between the conventional blade 22 and the tower 12.

This written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they include structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal languages of the claims.