The present disclosure relates in general to wind turbine rotor blades, and more particularly to vortex generators for wind turbine rotor blades having improved aerodynamic performance.
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, a generator, a gearbox, a nacelle, and one or more rotor blades. The rotor blades capture kinetic energy of wind using known foil principles. The rotor blades transmit the kinetic energy in the form of rotational energy so as 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.
In many cases, accessory components are attached to the rotor blades of wind turbines to perform various functions during operation of the wind turbine. For example, it is known to change the aerodynamic characteristics of wind turbine rotor blades by adding protrusions or other structures (often referred to as “vortex generators”) to the surface of the blade in order to increase the energy conversion efficiency during normal operation of the wind turbine by increasing the lift force of the blades while decreasing the drag force. The vortex generators serve to increase the attached-flow region and to reduce the detached-flow region by moving flow separation nearer the trailing edge of the blade. This is particularly desirable nearer to the blade root in order to increase the overall lift generated by the blade. In particular, the vortex generators create local regions of turbulent airflow over the surface of the blade as a means to prolong flow separation and thus optimize aerodynamic airflow around the blade contour. Conventional vortex generators are defined as “fins” or shaped structures on the suction side of the turbine blade. More specifically, many vortex generators include a flange portion with the fin extending therefrom.
The curvature of the blade surface that vortex generators attach to changes, which may require custom tooling and parts to fit every individual location on the rotor blade. Further, many vortex generators define a “step” at an interface between the flange portion and the surface of the rotor blade. In addition, installation techniques and systems for attaching conventional vortex generators can be quite expensive and time consuming, particularly for field installations. For example, typical field installation techniques require the use of attachment fixtures and significant dwell time for curing the attachment adhesives. The adhesives typically are considered hazardous materials and appropriate precautions and protective measures (both equipment and personal) must be taken.
Thus, improved vortex generators and methods of manufacturing and/or installing same would be welcomed in the art.
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 disclosure is directed to a vortex generator configured for mounting to either of a suction side or a pressure side of a rotor blade. The vortex generator includes a base portion having a curvature in an uninstalled state that substantially aligns with or conforms to a contour of a plurality of locations of either on the suction side or the pressure side of the rotor blade. Further, the vortex generator includes a protrusion member extending upwardly from the base portion. The protrusion member includes a plurality of tines separated by at least one slit. Moreover, the base portion and the protrusion member are constructed of a rigid material. In addition, the vortex generator includes a flexible coating material configured at least partially around the base portion and/or within or around the at least one slit.
In one embodiment, the flexible coating material may completely surround the base portion and the protrusion member. In another embodiment, the flexible coating material may have a hardness of from about 30 Shore A to about 105 Shore A. More specifically, in certain embodiments, the flexible coating material may be any suitable elastomer, including a thermoplastic material (such as an acrylic-styrene-acrylonitrile (ASA) polymer material), a thermoset material, or a rubber. Further, in particular embodiments, the rigid material may have a hardness of greater than about 105 Shore A. For example, in certain embodiments, the rigid material may include a fiber-reinforced composite, a thermoset material, a thermoplastic material, or any other suitable rigid material that provides the desired stiffness for the vortex generator.
In additional embodiments, a periphery of the injection-molded vortex generator may define an edge having a thickness equal to or less than 1 millimeter (mm). In yet another embodiment, the edge of the injection-molded vortex generator, or at least portions thereof, may curve downward.
In another embodiment, the vortex generator may have at least one adhesive application feature. For example, in certain embodiments, the adhesive application feature may include one or more flow channels configured with the base portion so as to promote adhesive flow, one or more resin ports configured to allow for easier injection of an adhesive, one or more weep holes configured to provide a visual indicator that sufficient adhesive has been applied, or any other suitable adhesive application features.
In another aspect, the present disclosure is directed to a rotor blade assembly for a wind turbine having a rotor blade with surfaces that define a pressure side, a suction side, a leading edge, and a trailing edge extending between a blade tip and a blade root. The rotor blade assembly also includes at least one injection-molded vortex generator mounted to either of the suction side or the pressure side of the rotor blade. The vortex generator includes a base portion and a protrusion member extending upwardly from the base portion. The base portion has a curvature (e.g. either constant or varying) in a length-wise direction and a varying curvature in a width-wise direction in an uninstalled state that substantially aligns with or conforms to a contour of a plurality of locations of either on the suction side or the pressure side of the rotor blade. Further, the base portion and the protrusion member are constructed of a single flexible, polymer material.
In one embodiment, the protrusion member may define a non-uniform gap with either of the suction side or the pressure side of the rotor blade when installed on the rotor blade.
In another embodiment, the base portion and the protrusion member may be separate components. In such embodiments, the protrusion member may be mounted to the base portion via at least one of one or more snaps, a snap or interference fit, one or more mechanical fasteners, an adhesive, or any other suitable attachment means. In alternative embodiments, the base portion and the protrusion member may be integral components.
In further embodiments, the single polymer material may have a hardness of from about 85 Shore A to about 100 Shore A. More specifically, in one embodiment, the single polymer material may include any suitable elastomer, including but not limited to a thermoplastic material (such as an acrylic-styrene-acrylonitrile (ASA) polymer material), a thermoset material, or a rubber.
In additional embodiments, the protrusion member of the vortex generator may have one or more slits configured to enhance flexibility thereof as well as a filler material configured within or around the one or more slits so as to maintain the aerodynamic properties of the protrusion member. For example, the filler material may include an adhesive, a sealant, or any other filler material configured within the slits, as well as a snap fit component or cap configured around or overlapping the slits. It should further be understood that the vortex generator may include any of the additional features as described herein.
In still further embodiments, the rotor blade assembly may further include an attachment layer connecting the base portion of the vortex generator to either the suction side or the pressure side of the rotor blade.
In yet another aspect, the present disclosure is directed to a method for manufacturing a rotor blade. The method includes providing a blade shell mold of the rotor blade. As such, the method also includes laying up one or more fiber materials into the blade shell mold and placing at least one vortex generator base portion into the blade shell mold. Further, the method includes infusing the one or more fiber materials and the vortex generator base portion together via a resin material so as to form the rotor blade such that the vortex generator base portion is located on an exterior surface of the rotor blade. Moreover, the method includes securing a protrusion member to the infused vortex generator base portion such that the protrusion member extends upwardly from the base portion.
In one embodiment, the method includes securing the protrusion member to the infused vortex generator base portion via at least one of one or more snaps, a snap or interference fit, one or more mechanical fasteners, an adhesive, or any other suitable attachment means. It should further be understood that the method may include any of the additional steps and/or features as described herein.
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.
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:
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.
Referring now to the figures,
Referring to
In some embodiments, the rotor blade 16 may include a plurality of individual blade segments aligned in an end-to-end order from the blade tip 32 to the blade root 34. Each of the individual blade segments may be uniquely configured so that the plurality of blade segments define a complete rotor blade 16 having a designed aerodynamic profile, length, and other desired characteristics. For example, each of the blade segments may have an aerodynamic profile that corresponds to the aerodynamic profile of adjacent blade segments. Thus, the aerodynamic profiles of the blade segments may form a continuous aerodynamic profile of the rotor blade 16. Alternatively, the rotor blade 16 may be formed as a singular, unitary blade having the designed aerodynamic profile, length, and other desired characteristics.
In further embodiments, the rotor blade 16 may be curved. Curving of the rotor blade 16 may entail bending the rotor blade 16 in a generally flap-wise direction and/or in a generally edgewise direction. The flap-wise direction may generally be construed as the direction (or the opposite direction) in which the aerodynamic lift acts on the rotor blade 16. The edgewise direction is generally perpendicular to the flap-wise direction. Flap-wise curvature of the rotor blade 16 is also known as pre-bend, while edgewise curvature is also known as sweep. Thus, a curved rotor blade 16 may be pre-bent and/or swept. Curving may enable the rotor blade 16 to better withstand flap-wise and edgewise loads during operation of the wind turbine 10, and may further provide clearance for the rotor blade 16 from the tower 12 during operation of the wind turbine 10.
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In addition,
Further, the vortex generator 102 may be placed at any location on either or both of the flow surfaces 22, 24 of the rotor blade 16 wherein it is desired to modify the aerodynamic characteristics of the surface. In a particular embodiment, the vortex generator 102 may have a different size and/or configuration depending on their span-wise location on the rotor blade 16. Moreover, as shown in
It should also be appreciated that the vortex generators 102 may have different shape configurations within the scope and spirit of the invention, and that the fin-type protrusion depicted in the figures is for illustrative purposes only. Any type of protrusion serving as a flow disrupter for improving the aerodynamic efficiency of the blade is within the scope of the invention.
Embodiments of vortex generators 102 are depicted in
Referring particularly to
In further embodiments, the attachment layer 110 may be applied as a continuous strip between the base portions 104 of adjacent vortex generators 102 and the underlying blade surface 24, or may be applied in a discontinuous pattern (e.g. as shown in
In addition, as shown in
Further, as shown in
Referring now particularly to
The high aspect ratio protrusion member 108 of the vortex generator 102 typically does not lend itself to flexing in the direction helpful to installation on a curved blade surface. As such, the present disclosure provides an injection-molded vortex generator 102 molded from a material that is both flexible enough to conform to all desired surfaces and stiff enough to prevent the protrusion member 108 from significantly distorting from aerodynamic pressure during operation. For example, in certain embodiments, the base portion 104 and the protrusion member 108 may be constructed of a single flexible material, e.g. such as a polymer material. More specifically, in certain embodiments, the single polymer material may have a hardness of from about 80 Shore A to about 105 Shore A, more preferably about 95 Shore A. In still further embodiments, the single polymer material may have a hardness of less than 80 Shore A or greater than 105 Shore A. Further, in particular embodiments, the single polymer material may include a thermoplastic material (such as an acrylic-styrene-acrylonitrile (ASA) polymer material), a thermoset material, or a rubber.
In the event that a single flexible material cannot meet both needs (i.e. flexible enough to conform to all desired surfaces and stiff enough to prevent the protrusion member 108 from significantly distorting from aerodynamic pressure during operation), a rigid component or insert comprising the base portion 104 and one or more tines (that will eventually form the protrusion member(s) 108) can be inserted into a mold and then coated, at least partially, with a flexible coating material. More specifically, the flexible coating material may be configured at least partially around the base portion 104 and/or within or around the slit(s) between the tines. In such embodiments, the rigid component may be constructed of any suitable rigid material, such as a fiber-reinforced composite, a thermoset material, a thermoplastic material, or any other suitable rigid material. Further, the rigid material may have a hardness of greater than about 105 Shore A. Moreover, the flexible coating material may be the same material as the single polymer material as described herein or may include any other flexible material. As such, the insert may serve at least two purposes. First, the insert provides a preferred flange bottom surface for adhesive bonding purposes since many flexible polymers can be difficult to bond to with preferred MMA adhesives. Second, the insert tines serve to provide stiffness to the flexible protrusion member 108 to prevent unwanted distortion during operation, while still allowing the protrusion member 108 to flex in the desired direction to promote conformability to the blade surface when mounted thereon. In addition, the insert also may serve to reduce overall material cost by using a less expensive rigid material for the insert to reduce volume of a potentially more expensive flexible material with UV resistance.
Functional components, such as the protrusion member 108, may be formed integral with the base portion 104, or separately attached to the base portion 104. If separate components, the protrusion member 108 may be mounted to the base portion 104 via at least one of one or more snaps, a snap or interference fit, mechanical fasteners, an adhesive, or any other suitable attachment means. For example, as shown in
In additional embodiments, the use of injection molding allows for the production of very thin edges 106 of the base portion 104 so as to reduce aerodynamic disturbance and eliminate any benefit or need for an adhesive or sealant around a periphery thereof for airflow reasons. For example, as shown in
Referring now to
In further embodiments, as shown in
In addition, as shown in
Further, as shown in
Referring now to
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.