Patent Publication Number: US-2018038342-A1

Title: Vortex generators for wind turbine rotor blades

Description:
FIELD OF THE INVENTION 
     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. 
     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, 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. 
     BRIEF DESCRIPTION OF THE INVENTION 
     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. 
    
    
     
       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 a conventional wind turbine; 
         FIG. 2  illustrates a perspective view of one embodiment of a rotor blade assembly according to the present disclosure; 
         FIG. 3  illustrates a partial top view of another embodiment of a rotor blade assembly according to the present disclosure, particularly illustrating a plurality of vortex generators; 
         FIG. 4  illustrates a partial cross-sectional view of one embodiment of rotor blade assembly according to the present disclosure; 
         FIG. 5  illustrates a partial cross-sectional view of another embodiment of rotor blade assembly according to the present disclosure; 
         FIG. 6  illustrates a length-wise cross-sectional view of one embodiment of a vortex generator along a center line thereof according to the present disclosure, particularly illustrating a base portion of the vortex generator having a curvature that substantially aligns with or conforms to the contour of the blade surface of the rotor blade; 
         FIG. 7  illustrates a length-wise cross-sectional view of another embodiment of a vortex generator along a center line thereof according to the present disclosure mounted on a rotor blade surface, particularly illustrating a non-uniform gap between the underside of the protrusion member and the blade surface; 
         FIG. 8  illustrates a perspective bottom-side view of one embodiment of a vortex generator according to the present disclosure, particularly illustrating the curvature of the base portion of the vortex generator; 
         FIG. 9  illustrates a length-wise cross-sectional view of still another embodiment of a vortex generator along a center line thereof according to the present disclosure, particularly illustrating a base portion of the vortex generator having edges that curve downward; 
         FIG. 10  illustrates a length-wise side view of another embodiment of a vortex generator according to the present disclosure, particularly illustrating the protrusion member and the base portion of the vortex generator as separate components being joined via corresponding connecting features; 
         FIG. 11  illustrates a length-wise cross-sectional view of yet another embodiment of a vortex generator along a center line thereof according to the present disclosure, particularly illustrating a protrusion member of the vortex generator having a plurality of slits configured to enhance flexibility thereof; 
         FIG. 12  illustrates a bottom-side view of one embodiment of a vortex generator according to the present disclosure, particularly illustrating a plurality of flow channels configured in the base portion thereof; 
         FIG. 13  illustrates a length-wise side view of one embodiment of a vortex generator according to the present disclosure, particularly illustrating a plurality of flow channels configured in the base portion thereof; 
         FIG. 14  illustrates a width-wise side view of another embodiment of a vortex generator according to the present disclosure, particularly illustrating a resin port configured with the base portion thereof; 
         FIG. 15  illustrates a width-wise side view of yet another embodiment of a vortex generator according to the present disclosure, particularly illustrating a plurality of weep holes configured with the base portion thereof; 
         FIG. 16  illustrates a width-wise side view of still another embodiment of a vortex generator according to the present disclosure, particularly illustrating a plurality of weep holes configured in thin edges of the base portion thereof; 
         FIG. 17  illustrates a width-wise side view of a further embodiment of a vortex generator according to the present disclosure, particularly illustrating a plurality of weep holes configured in inserts that are infused with the base portion thereof; and 
         FIG. 18  illustrates a flow diagram of embodiment of a method for manufacturing a rotor blade according to the present disclosure. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     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,  FIG. 1  illustrates a wind turbine  10  of conventional construction. The wind turbine  10  includes a tower  12  with a nacelle  14  mounted thereon. A plurality of rotor blades  16  are mounted to a rotor hub  18 , which is in turn connected to a main flange that turns a main rotor shaft (not shown). The wind turbine power generation and control components are housed within the nacelle  14 . The view of  FIG. 1  is provided for illustrative purposes only to place the present invention in an exemplary field of use. It should be appreciated that the invention is not limited to any particular type of wind turbine configuration. 
     Referring to  FIG. 2 , a rotor blade assembly  100  in accordance with aspects of the invention is illustrated. As shown, the rotor blade assembly  100  includes a rotor blade  16  having surfaces defining a pressure side  22  and a suction side  24  extending between a leading edge  26  and a trailing edge  28 . Further, the rotor blade  16  may extend from a blade tip  32  to a blade root  34 . The surfaces defining the pressure side  22 , the suction side  24 , the leading edge  26 , and the trailing edge  28  further define a rotor blade interior or cavity. Further, the rotor blade  16  defines a chord  42  and a span  44 . As shown, the chord  42  may vary throughout the span  44  of the rotor blade  16 . Thus, a local chord may be defined for the rotor blade  16  at any point on the rotor blade  16  along the span  44 . 
     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 . 
     Still referring to  FIG. 2 , the rotor blade  16  defines a pitch axis  40  relative to the rotor hub  18 . For example, the pitch axis  40  may extend generally perpendicularly to the rotor hub  18  and blade root  34  through the center of the blade root  34 . A pitch angle or blade pitch of the rotor blade  16 , i.e., an angle that determines a perspective of the rotor blade  16  with respect to the air flow past the wind turbine  10 , may be defined by rotation of the rotor blade  16  about the pitch axis  40 . 
     In addition,  FIG. 2  further depicts a plurality of vortex generators  102  located on the suction side  24  of the rotor blade  16  along the span  44  thereof. More specifically, in the illustrated embodiment, the vortex generators  102  are configured in pairs to define generally V-shaped formations oriented towards the leading edge  28  of the rotor blade  16 . In further embodiments, the vortex generators  102  may be arranged in any suitable formation in addition to the V-shaped formation. Further, it should be understood that the vortex generators  102  are depicted on the suction side surface  24  of the blade  16  for illustrative purposes only and maybe also be provided on the pressure side surface  22 . 
     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  FIG. 2 , there are three groupings of vortex generators  102 , with the grouping closest to the blade root  34  being larger (or having an overall different shape or configuration) as compared to the adjacent groupings. In alternate embodiments, all of the vortex generator  102  may be disposed closer to a root portion  34  of the blade as compared to a tip portion  32 , or closer to the tip portion  32  as compared to the root portion  34 . It should be understood that the invention is not limited to any particular placement of the vortex generators  102  on either or both flow surfaces  22 ,  24  of the blade  16 . 
     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  FIGS. 3-13 . More specifically, the vortex generators  102  of the present disclosure are preferably formed via injection-molding, the benefits of which are described herein. Further, as shown, each vortex generator  102  includes a base portion  104  and a protrusion member  108  extending upwardly from the base portion  104 . More specifically, as shown in the figures in general, the vortex generators  102  include a single protrusion member  108  extending upwardly from each respective base portion  104 . In further embodiments, the vortex generators  102  may include a plurality of protrusion members  108  extending upwardly from the base portion  108 . As mentioned, the protrusion member  108  may be any suitable flow disrupting configuration, such as a fin, or like structure. The invention in its broadest aspects is not limited to any particular shape or configuration of vortex generator or flow disruption protrusion member  108 . The base portion  104  may be defined as a generally continuous structure that presents a surface that contours and adheres to the mating blade surface. 
     Referring particularly to  FIGS. 4-6 , an attachment layer  110  is configured to connect the base portion  104  of the vortex generator  102  to the respective suction or pressure side  22 ,  24  of the rotor blade  16 . In a particular embodiment, the attachment layer  110  may be a double-sided adhesive sheet or strip material  112 , such as a Very High Bond (VHB)/SAFT (Solar Acrylic Foam Tape) foam-based tape. Various examples of VHB/SAFT foam-based materials are commercially available, for example from 3M Corporation of St. Paul, Minn., USA. The foam attachment layer  112  will shear a small but defined amount with flexing of the underlying blade surfaces, thus reducing shear stresses in the vortex generator  102 . In addition, the attachment layer  110  may be selected to have a particular thickness  116  that provides the desired shear slippage or strain isolation characteristic without adding a detrimental height aspect that could adversely affect the aerodynamic performance of the blade  16 . For example, the adhesive tape may have a thickness between 0.5 mm and 5.0 mm. In addition, as shown in  FIG. 5 , the attachment layer  110  may include a layer of resin or putty  114  between the strip/sheet material layer  112  (such as a foam-based layer as described above) and the underlying blade surface. 
     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  FIG. 4 ). For example, as shown in  FIG. 5 , the attachment layer  110  may include a plurality of distinct strips  112  (e.g., tape or sheet strips) with a chord-wise gap  118  between adjacent strips. In other embodiments, the attachment layer  110  may include span-wise gaps between distinct strips  112 . In yet another embodiment, as shown in  FIG. 6 , the attachment layer  110  may include double-faced adhesive tape about the periphery of the base portion  104  and an adhesive in the middle. 
     In addition, as shown in  FIGS. 4 and 5 , each of the base portions  104  may have a respective attachment layer  110  that does not span the gap  118 . Thus, the gaps  118  allow for relative shear slippage between the different base portions  104 . In addition, in certain embodiments, fillet seals  120  may be provided at the edges of the respective base portions  104  to protect the attachment layer  110  from moisture or other elements. The seals  120  may be, for example, any type of flexible caulking material. 
     Further, as shown in  FIG. 4 , the attachment layer  110  may be applied around the periphery edge  106  of the base portion  104  of the vortex generator  102 . For example, as shown, high-tack adhesive may be used outside of the periphery edge  106  of the base portion  104  to provide a sealed surface to prevent squeeze out of adhesive when the vortex generator  102  is applied to the blade surface and/or when adhesive is injected in between the vortex generator  102  and rotor blade  16 . In such embodiments, the periphery attachment layer  110  is not required to overlap the edge  106  of the vortex generator  102  due to the thin edges created by injection molding, which is discussed herein below. In addition, as shown, the periphery attachment layer  110  may be substantially the same thickness as the edge  106  of the base portion  104 . 
     Referring now particularly to  FIGS. 6-8 , the base portion  104  of the vortex generator  102  may have a contour  124  in both a length-wise direction and a width-wise direction in an uninstalled state that is configured to align with a curvature of a plurality of locations of either on the suction side  24  or the pressure side  22  of the rotor blade  16 . More specifically, as shown in  FIG. 8 , the curvature in the length-wise direction may be constant or varying, whereas the curvature in the width-wise direction may vary along a length of the protrusion member  108 . For example, as shown, the radius of curvature at the edges of the base portion  104  is equal to R 1  and increases towards the center from R 2  to R 3 . By applying such curvature (i.e. in either or both of the length-wise and/or width-wise directions), the base portion  104  provides flexibility for installation at multiple locations on the blade surface. In other words, as shown in  FIG. 7 , the base portion  104  of the vortex generator  102  is configured to conform to the blade surface, wherein the protrusion member  108  does not, thereby leaving a non-uniform gap  122  between the underside of the protrusion member  108  and the blade surface which is accounted for typically by adhesive (e.g. the attachment layer  110 ). More specifically, as shown, the gap varies along the length of the protrusion member  108  such that the edges of the base portion  104  contact the blade surface and the center of the base portion is separated from the blade surface by gap  122 . Thus, the view of  FIG. 7  is a cross-sectional view along a center line of the base portion  104 . As such, the vortex generator  102  may be secured to the blade surface via an attachment layer  110  at its edges only (as shown) as well as by filling in the gap  122  with the attachment layer  110 . The varying gap  122  may have any suitable height, but typically ranges from about zero millimeters (mm) at the edges of the base portion  104  to about 3 mm at the center. 
     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  FIG. 10 , the protrusion member  108  and the base portion  104  are illustrated as separate components that can be joined together using a snap fit created by corresponding connecting features  105 . In further embodiments, the protrusion member  108  and the base portion  104  may be joined together using a combination of attachment means, e.g. a snap fit and an adhesive. 
     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  FIGS. 3 and 4 , a periphery of the injection-molded vortex generator  102  may define a periphery edge  106  having a thickness equal to or less than 1 millimeter (mm). In further embodiments, as shown in  FIG. 9 , the thin-edge base portions  104  can be further curved downward to ensure ideal contact with one or more blade surfaces and shape. 
     Referring now to  FIG. 11 , the protrusion member  108  of the vortex generator  102  may further include one or more slits  126  or slots configured therein to enhance flexibility thereof. More specifically, the slits or slots may extend entirely through the protrusion member  108  of the vortex generator  102  or only partially through the protrusion member  108 . In addition, as shown, the slits  126  may be filled with a filler material, such as an adhesive as described herein, so as to maintain the aerodynamic properties of the protrusion member  108 . 
     In further embodiments, as shown in  FIGS. 12-17 , the vortex generator(s)  102  of the present disclosure may also include at least one adhesive application feature  130 . For example, as shown in  FIGS. 12 and 13 , the adhesive application feature  130  may include one or more flow channels  132  configured with the base portion  104  of the vortex generator  102  so as to promote and/or direct adhesive flow. More specifically, as shown in  FIG. 12 , a bottom-side of the base portion  104  is illustrated that includes two flow channels  132  configured longitudinally therein. Further,  FIG. 13  illustrates a side view of the flow channel  132 . It should be understood that any number of flow channels  132  may be included in the base portion  104  of the vortex generator  102  and may extend in any suitable direction. 
     In addition, as shown in  FIG. 14 , the adhesive application feature(s)  130  may include one or more resin or injection ports  134  configured with the base portion  104  of the vortex generator  102  so as to allow injection of an adhesive. More specifically, as shown, the resin ports  134  may be configured at any suitable location on the base portion  104  including the top of the base portion  104  as well as the sides of the base portion  104 . As such, the resin port(s)  134  provide an easily accessible location (e.g. typically exterior of the base portion  104 ) for adhesive injection that allows adhesive to be inserted therethrough and flow through one or more of the flow channels  132 . 
     Further, as shown in  FIGS. 15-17 , the adhesive application feature(s)  130  may include one or more weep holes  136  so as to provide a visual indicator that sufficient adhesive has been applied to the blade surface. For example, as shown, the weep holes  136  may be through holes extending through the thickness of the base portion  104 . In addition, as shown in  FIG. 16 , the weep holes  136  may be configured at thin areas  138  or edges of the base portion  104  such that an adhesive can be easily viewed through the base portion  104 . As such, a user can visual detect when a sufficient amount of adhesive has been applied. Further, as shown in  FIG. 17 , the base portion  104  may be formed with more or more inserts  140  of a transparent material. As such, the weep holes  136  may be configured or infused with the inserts  140  such that a user can visually detect when a sufficient amount of adhesive has been applied through the transparent material. Moreover, as shown, the weep holes  136  may be evenly spaced randomly spaced and may be any suitable size and/or shape. In addition, any suitable number of weep holes  136  may be utilized and may depend upon the size and/or shape of the base portion  104  of the vortex generator  102 . 
     Referring now to  FIG. 18 , a flow diagram of one embodiment of a method for manufacturing a rotor blade, e.g. such as the rotor blade  16  of  FIG. 2 . As shown at  202 , the method  200  includes providing a blade shell mold of the rotor blade  16 . For example, in one embodiment, the blade shell mold may include two blade halves. As shown at  204 , the method  200  includes laying up one or more fiber materials into the blade shell mold and placing at least one injection-molded vortex generator base portion  104  into the blade shell mold. The fiber material(s) as described herein may include but are not limited to glass fibers, carbon fibers, metal fibers, polymer fibers, ceramic fibers, nanofibers, or similar, or any combinations thereof. As shown at  206 , the method  200  also includes infusing the one or more fiber materials and the vortex generator base portion  104  together via a resin material so as to form the rotor blade  16  such that the vortex generator base portion  104  is located on an exterior surface of the rotor blade  16 . As shown at  208 , the method  200  further includes securing a protrusion member  108  to the infused vortex generator base portion  104  such that the protrusion member  108  extends upwardly from the base portion  104 . For example, in one embodiment, the protrusion member  108  may be secured to the infused vortex generator base portion  104  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, or combinations thereof. 
     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.