A method of manufacturing a shell of a wind turbine blade.

Field of the Invention

The present invention relates to a wind turbine blade. Further embodiments, of the dis closure discloses about the method of manufacturing a shell of the wind turbine blade. In addition, the present invention relates to methods of joining a spar element to the shell of the blade during manufacturing said blade using resin infusion process.

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 re gard. A modem wind turbine typically includes a tower, a generator, a gearbox, a nacelle, and a rotor having a rotatable hub with one or more rotor blades. The rotor blades capture kinetic energy of wind using known airfoil principles. The rotor blades transmit the ki netic energy in the form of 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.

The rotor blades generally include a suction side shell and a pressure side shell typically formed using molding processes that are bonded together at bond lines along the leading and trailing edges of the blade. Further, the pressure and suction shells are relatively light weight and have structural properties (e.g., stiffness, buckling resistance and strength) which are not configured to withstand the bending moments and other loads exerted on the rotor blade during operation. Thus, to increase the stiffness, buckling resistance and strength of the rotor blade, the body shell is typically reinforced using one or more struc tural components (e.g. opposing spar caps with a shear web configured therebetween) that engage the inner pressure and suction side surfaces of the shell halves. The spar caps are typically constructed of various materials, including but not limited to glass fiber laminate composites and/or carbon fiber laminate composites. The shell of the rotor blade is gen erally built around the spar caps of the blade by stacking layers of fiber fabrics in a shell mold. The layers are then typically infused together, e.g. with a thermoset resin. Such rotor blades, however, are not without issues. The blade components such as spar receiving sections (e.g. for sectionized blades), beam structures, shear webs and the like are conventionally adhered to the shells by bonding pastes such as adhesives. These bond ing pastes would the defining a typical bonding line on the shell of the wind turbine blade. The bond lines of typical rotor blades are generally formed by applying a suitable bonding paste (i.e. adhesives) or compound along the bond line with a minimum designed bond width between the shell members. These bonding lines are a critical design constraint of the blades as a significant number of turbine blade field failures occur at the bond-line. Also, the use of bonding paste to adhere components of the wind turbine blade such as the spar element, shear webs and other blade components that are mentioned above, which lead to catastrophic failure of the blades over a period of time. At the joint portions of the blade the concentrated load transfer makes the connection more demanding, and the limitations of the weak adhesive connections limit the design capability and add risk of failure. Also, use of such bonding paste over the blade of wind turbine reduces or limits the design features due to the high concentrated loads.

An additional concern when joining components of a rotor blade together is maintaining the aerodynamic contour of the rotor blade. In many cases, due the complexity of the join ing process, the aerodynamic contour of one or more components being joined can be altered from a desirable aerodynamic contour for that component. For example, an adhe sive connection consists of two structural layers each capable of carrying the primary loads and the adhesive that transfers the load. Typical adhesive connections are 5- 15mm thick, when combined with the additional structure can add 25mm to each side of the blade compared to a comparable non-bonded method. Either the internal structural space is limited, resulting in a shorter blade than possible, or the blade must be thicker to ac commodate the extra material, resulting in decreased aerodynamic performance. Either current approach decreases turbine annual energy production (AEP) by 2 to 5%, with a typical contemporary turbine providing a business and customer value of $100,000 per 1% of AEP

Accordingly, improved systems and methods for joining blade components of rotor blades are desired. In particular, systems and methods which reduce the time and expense associated with joining of the blade components, and which maintain the aerodynamic contour of the rotor blade, would be advantageous.

Summary of the Invention

One or more shortcomings of the conventional methods are overcome by the methods as claimed and additional advantages are provided through the provision of assembly as claimed in the present invention.

Additional features and advantages are realized through the techniques of the present in vention. Other embodiments and aspects of the disclosure are described in detail herein and are considered as a part of the claimed disclosure.

In one non-limiting embodiment of the disclosure, a method of manufacturing a shell of a wind turbine blade is disclosed. The method of manufacturing includes laying one or more layers of shell or spar fibers on a surface of mould to form a portion of the blade shell. The shell of the wind turbine blade includes a first shell half structure and a second shell half structure. A spar element is positioned at a pre-defined position on the one or more layers of fiber. The term pre-defined position may be construed as a positioning of the shear web at a substantially central portion of the first shell half structure and/or the second shell half structure. It should be understood that the spar element may also be positioned on the second shell half structure of the root end segment of the blade 28 and may be adhered to the second shell half structure. The spar element is positioned on at least one of the first shell half structure and the second shell half structure. A vacuum bag is positioned or covered around the one or more layers of fiber and the spar element. The vacuum bag is configured to seal the spar element and the one or more layers of fiber. A resin is infused through the one or more layers of fiber and the spar elements. Upon in fusing the resin through the vacuum bag and through the one or more layers of fiber and spar element, the resin is subsequently allowed to cure to obtain the first shell half struc ture and the second shell half structure. In the process of infusing the resin through the one or more fiber and spar element and curing the resin, the spar element is adhered to the shell i.e. at least one of the first shell half structure or the second shell half structure. It is clear that the shell or spar fibers refers to layers of fibers. The shell fiber (or shell fiber layers) may form part of an aerodynamic shell, and the spar fibers (or spar fiber layers) may form part of the spar construction, e.g. at least part of a spar cap. It is further clear that the reference to the one or more layers of fibers refer to the shell or spar fibers (or shell fiber layer(s) or spar fiber layer(s)).

The spar element is preferably a pre-manufactured part, such as a precured composite structure.

In a preferred embodiment of the disclosure, the spar element is a spar beam receiver box, or section thereof.

In a preferred embodiment of the disclosure, the resin includes a polyester compound. The polyester compound is preferably at least one of a vinyl ester or epoxy resins.

In certain embodiment of the disclosure includes positioning a shear web at a substantially central portion of the shell. The shear web extends along length of the shell up to the position of the spar element. The end of the shear webs proximal to the spar element is connected to the shear web. In other words, the shear web of the main blade section is connected to the shear web of the spar element. The shear web is preferably pre-manu- factured part, such as a precured composite structure.

In a preferred embodiment of the disclosure, the resin is infused through a vacuum infu sion process.

In another non-limiting embodiment of the disclosure, a method for joining a spar element to a wind turbine blade part (or joining a spar element to blade shell) is disclosed. The method includes positioning the shell of the wind turbine blade on a mould. The shell of the wind turbine blade includes at least one of a first shell half structure or a second shell half structure. A spar element is positioned at a pre-defined position over the at least one of the first shell half structure or the second shell half structure or spar cap of the wind turbine blade. A portion of the spar element that is in contact with the shell (i.e. at least one of the first shell half structure and the second shell half structure) or the spar cap is defined with a flow path. Resin is infused between the spar element and the shell or the spar cap. The resin is infused through the flow path and is subsequently cured, thereby adhering the spar element to the shell or the spar cap. In a preferred embodiment of the disclosure, the one or more layers of fibers on the mould are glass fibers In another embodiment, the one or more layers of fibers are carbon fibers or carbon-glass hybrid layers.

In another non- limiting embodiment of the disclosure, a method for manufacturing a root end of the wind turbine blade is disclosed. The method includes forming a first shell half structure and a second shell half structure separately in a mould. A spar element is joined to at least one of the first shell half structure and the second shell half structure by resin infusion process in the mould. Positioning a shear web at a substantially central portion of the first shell half structure and the second shell half structure. The shear web extends in a spanwise direction up to the spar element. The method further includes joining an end of the spar element and the shear web by resin infusion process. The first shell half structure and the second shell half structure are joined and sealed together to obtain root end of the wind turbine blade.

In a preferred embodiment, the spar element is bonded to the remaining of the first shell half structure or the second shell half structure before joining of the first shell half struc ture and the second shell half structure.

In a preferred embodiment of the disclosure, the first shell half structure and the second shell half structure are formed by laying plurality of layers of fiber in the mould and infusing resin and subsequently curing the resin.

In a preferred embodiment of the disclosure, a first half of the spar element is bonded to the first shell half structure and a second half of the spar element is bonded to the second shall half structure. The first half and second half of the spar element is bonded to each other before joining the first shell half structure and the second shell half structure. The first half and/or the second half of the spar element are preferably pre-fabricated parts, such as precured composite structures.

As used herein, the term "spanwise" is used to describe the orientation of a measurement or element along the blade from its root end to its tip end. In some embodiments, spanwise is the direction along the longitudinal axis and longitudinal extent of the wind turbine blade. The term “chordwise” is used to describe the orientation of a measurement or element from its leading edge to its trailing edge. In some embodiments, chordwise is the direction along the lateral axis and lateral extent of the wind turbine blade

It is to be understood that the aspects and embodiments of the disclosure described above may be used in any combination with each other. Several of the aspects and embodiments may be combined to form a further embodiment of the disclosure.

The foregoing summary is illustrative only and is not intended to be in any way limiting. In addition to the illustrative aspects, embodiments, and features described above, further aspects, embodiments, and features will become apparent by reference to the drawings and the following detailed description.

Description of the Invention

The invention is explained in detail below with reference to an embodiment shown in the drawings, in which

Fig. 1 illustrates a perspective view of one embodiment of a wind turbine,

Fig.2 illustrates a perspective view of a wind turbine blade, in accordance with an em bodiment of the disclosure,

Fig. 3 illustrates a plan view of one embodiment of a rotor blade having a first blade segment and a second blade segment,

Fig. 4 illustrates a perspective view of a section of one embodiment of tip end of the blade,

Fig. 5 illustrates a perspective view of one embodiment of a section of the root end of the blade at the chord- wise joint,

Fig. 6 illustrates an assembly of one embodiment of the rotor blade of the wind turbine having a tip end joined to with the root end segment,

Fig. 7 illustrate an exploded perspective view of one embodiment of the multiple support ing structures of the assembly of the rotor blade of the wind turbine;

Figs. 8a-d illustrates different cross-sections of the receiving section of the spar element; Figs. 9 and 10 illustrates step-by-step method of joining a spar element to the shell of the wind turbine blade by resin infusion process;

FIG.lla illustrates a perspective view of a mould used to manufacture the shell of the wind turbine blade by resin infusion process, in accordance with an embodiment of the disclosure,

FIG.1 lb and 1 lc is a flowchart of the method of manufacturing a wind turbine blade, in accordance with an embodiment of the present disclosure

FIG. 12 illustrates schematic view of the spar element connected to the shear web of the wind turbine blade by resin infusion process; and

FIGs.13 and 14 illustrates various configurations for connecting the spar element to the shear web by resin infusion process.

Detailed Description

Reference now will be made in detail to embodiments of the invention, one or more ex amples 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, 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 if 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 drawings, FIG. 1 illustrates a perspective view of one embodiment of a wind turbine 10 according to the present invention. In the illustrated embodiment, the wind turbine 10 is a horizontal- axis wind turbine. Alternatively, the wind turbine 10 may be a vertical-axis wind turbine. In addition, as shown, the wind turbine 10 may in clude a tower 12 that extends from a support surface 14, a nacelle 16 mounted on the tower 12, a generator 18 positioned within the nacelle 16, a gearbox 20 coupled to the generator 18, and a rotor 22 that is rotationally coupled to the gearbox 20 with a rotor shaft 24. Further, as shown, the rotor 22 includes a rotatable hub 26 and at least one rotor blade 28 coupled to and extending outward from the rotatable hub 26. As shown, the rotor blade 28 includes a blade tip 17 and a blade root 19.

Fig. 2 shows a schematic view of a rotor blade 28. The rotor blade 28 has the shape of a conventional wind turbine blade and comprises a root region 19 closest to the hub, a pro filed or an airfoil region 34 farthest away from the hub and a transition region 32d be tween the root region 19 and the airfoil region 32c. The blade 28 comprises a leading edge facing the direction of rotation of the blade 28, when the blade 28 is mounted on the hub, and a trailing edge facing the opposite direction of the leading edge.

The airfoil region 32c (also called the profiled region) has an ideal or almost ideal blade shape with respect to generating lift, whereas the root region 19 due to structural consid erations has a substantially circular or elliptical cross-section, which for instance makes it easier and safer to mount the blade 28 to the hub. The diameter (or the chord) of the root region 19 may be constant along the entire root area. The transition region 32d has a transitional profile gradually changing from the circular or elliptical shape of the root region 19 to the airfoil profile of the airfoil region. The chord length of the transition region 32d typically increases with increasing distance r from the hub. The airfoil region has an airfoil profile with a chord extending between the leading edge and the trailing edge of the blade 28. The width of the chord decreases with increasing distance r from the hub.

A shoulder 32e of the blade 28 is defined as the position, where the blade 28 has its largest chord length. The shoulder is typically provided at the boundary between the transition region 32d and the airfoil region. Fig. 2 also illustrates the longitudinal extent L, length or longitudinal axis of the blade.

It should be noted that the chords of different sections of the blade normally do not lie in a common plane, since the blade may be twisted and/or curved (i.e. pre-bent), thus provid ing the chord plane with a correspondingly twisted and/or curved course, this being most often the case in order to compensate for the local velocity of the blade being dependent on the radius from the hub. The blade is typically made from a first shell half structure and a second shell half struc ture that are glued to each other along bond lines at the leading edge and the trailing edge of the blade 28.

Referring now to FIG. 3, a schematic view of a cross section of one of the rotor blades 28 of FIG.1 is illustrated. In an embodiment, the rotor blade 28 may hereinafter alternatively be referred as blade. As shown, the rotor blade 28 may include a tip end segment 30 and a root end segment 32. Further, as shown, the tip end segment 30 of the blade 28 and the root end segment 32 of the blade 28 may each extend in opposite directions from a chord- wise joint 34. In addition, as shown, each of the blade segments 30, 32 may include at least one shell member defining an airfoil surface, such as a first shell half structure and a second shell half structure. The tip end segment 30 and the root end segment 32 are connected by at least an internal support structure 36 to facilitate joining of the tip end segment 30 and root end segment 32. The arrow 38 shows that the segmented rotor blade 28 in the illustrated example includes the tip end segment 30 and the root end segment 32 and are joined by inserting the internal support structure 36 into the root end segment 32. In addition, as shown, the root end segment includes multiple spar structures 66 (also re ferred to herein as spar caps) that extend lengthwise for connecting with the beam struc ture 40 of the tip end segment 30 (which is shown in more detail in FIGS. 3 and 5).

Referring now to FIG. 4, a perspective view of a section of the tip end segment 30 ac cording to the present invention is illustrated. As shown, the tip end segment 30 includes a beam structure 40 that forms a portion of the internal support structure 36 and extends lengthwise for structurally connecting with the root end segment 32. Further, as shown, the beam structure 40 forms at least a part of a shear web 42 (i.e. shear web on the tip end segment of the blade) connected with a suction side spar cap 44 and a pressure side spar cap 46. Moreover, as shown, the tip end segment 30 may include one or more first pin joints at a receiving end 54 of the beam structure 40. In one embodiment, the pin joint may include a pin that is in a tight interference fit with a bushing. More specifically, as shown, the pin joint(s) may include at least one pin tube 52 located on the receiving end 54 of the beam structure 40. Thus, as shown, the pin tube 52 may be oriented in a span-wise direction. Further, the tip end segment 30 may also include a pin joint slot 50 located on the beam structure 40. Moreover, as shown, the pin joint slot 50 may be ori ented in a chord-wise direction.

Referring now to FIG. 5, a perspective view of a section of the root end segment 32 ac cording to the present invention is illustrated. As shown, the root end segment 32 includes a spar element 60a. The spar element 60a may be defined with a receiving section 60. The receiving section 60 of the spar element 60a may extend lengthwise to a predetermined length within the root end segment 32 for receiving the beam structure 40 of the tip end segment 30. Further, as shown, the receiving section 60 may include the spar structures 66 that extend lengthwise for connecting with the beam structure 40 of the tip end seg ment 30. In addition, as shown, the receiving section 60 may include a chord-wise mem ber 48 [as can be seen in FIG.6] having a span- wise pin joint slot 56 defined therethrough. Moreover, as shown, the receiving section 60 may include a chord- wise pin joint slot 58 defined therethrough that aligns with the pin joint slot 50 of the beam structure 40.

Referring now to FIG. 6, an assembly 70 of the rotor blade 28 having the tip end segment 30 joined with the root end segment 32 according to the present invention is illustrated. As shown, the assembly 70 illustrates multiple supporting structures beneath outer shell members of the rotor blade 28 having the tip end segment 30 joined with the root end segment 32. More specifically, as shown, the span-wise extending pin 52 of the receiving end 54 of the beam structure 40 is received within the span-wise pin joint slot 56 of the receiving section 60 so as to secure the first and second blade segments 30, 32 together. Referring now to FIG. 6, an exploded perspective view of the multiple support ing structures of the assembly 70 towards the receiving section 60 of the rotor blade 28 is illustrated. As shown, the spar structures 66 are configured to receive the beam structure 40 and may include the chord-wise pin joint slot 58 that align with the pin joint slot 50 of the beam structure 40 through which a chord-wise extending pin 62 may be inserted. Fur ther, as shown, the chord-wise extending pin 62 may be configured to remain in a tight interference fit within the aligning pin joint slots 50, 58 such that spar structures 66 and the beam structure 40 are joined during assembly. Further, FIG. 6 also illustrates the chord-wise member 48 that includes the pin joint slot 56 configured for receiving the pin tube 52 (also referred to herein as the span-wise extending pin 52) of the beam structure 40. As such, the pin tube 52 is configured to form a tight interference fit pinned joint. Exemplary cross-sectional shapes of spar element 60a are shown in FIGS. 8A to 8C. FIG. 8A shows a spar element 60a having a rectangular cross-section. It should be understood that also a square cross-section is comprised within the meaning of the term ‘rectangular’ . According to another embodiment of the present invention shown in FIG. 8B, the spar element 60a has an elliptical cross-section. It should be understood that also a circular cross-section is comprised within the meaning of the term ‘elliptical’. An even further embodiment of the present invention is shown in FIG. 8C. Therein, the cross-sectional shape of spar element 60a is adjusted to the cross-sectional shape of the wind turbine ro tor blade 28. The cross-sectional shape is basically rectangular, but the upper and lower connecting surfaces are curved so as to follow the shape of the blade shells. Alt hough FIGS. 8A to 8C show the cross-sectional shape of spar element 60a, it should be understood that the cross-sectional shapes of beam structure 40 will be selected to corre spond with the cross-sectional shape of receiving section 60. In some embodiment, the spar element 60a may be a multi-piece receiver section. As shown in FIG.8D, the receiver section may be prefabricated into two halves. In further embodiments of the disclosure, the method of adhering the receiving section 60 to the at least one of the first shell half structure or the second shell half structure of the wind turbine blade 28 is substantiated with reference to FIGs 9 and 10.

Referring now to FIGs 9 and 10, which illustrates method of manufacturing the wind turbine blade 28 including the spar element 60a. In an embodiment, the first shell half structure and the second shell half structure of the wind turbine blade 28 may be manu factured by a moulding process using a mould 103. Fig. 11a illustrates a schematic side view of a mould 103 for manufacturing shell half structures of the wind turbine blade 28. In addition to the method substantiated hereinbelow, the method is also depicted in the way of flowcharts in the FIG(s) lib and 11c. The pressure and suction side shells of the wind turbine blade 28 are manufactured using the mould 103 as shown in FIG.lla. The mould 103 may be defined with an outer surface 103a and an inner surface 103b. The inner surface of the mould 103 is aerodynamic. In an embodiment, the first shell half structure 30a and 32a, and the second shell half structure 30b and 32b for the root end segment 32 and the tip end segment 30 may be manufactured in a single mould 103. Initially, a blade gel coat or primer is typically applied to the inner surface 103b of the mould 103. Further, fiber reinforcement and/or fiber fabrics are placed into the inner sur face 103b of the mould 103. A plurality of layers of fibers may be positioned on the inner surface 103b of the mould 103. In an embodiment, the plurality of layers of fibers may include aramid fiber fabrics, glass fibers, carbon fiber fabrics or hybrid fiber fabrics made of glass and carbon. Other, fiber fabrics not limiting to the above-mentioned fabrics which are known in the art may also be used. In some embodiments, the fibers used may be in any form such as but not limiting to fabrics, prefabricated structures such as pultrusion’s or loose fibers.

Upon placing the plurality of layers of fibers on the mould, the spar element 60a may be positioned on the at least one of the first shell half structure 32a or the second shell half structure 32b of the root end segment 32 of the blade 28. In an embodiment, the spar element 60a may be positioned proximal to the chord-wise joint 34. The spar element 60a may be configured to receive the beam structure 40 and may also be referred to as spar beam receiver section. In a preferred embodiment, the spar element 60a may be a prefab ricated structure. The spar element 60a is positioned preferably on the first shell half structure 32a of the root end segment 32. Further, a vacuum bag 100 may be used to seal and close the mould comprising the plurality of layers of fibers and the spar element 60a. A high vacuum pump may be used to remove air in a cavity created by the vacuum bag 100 and the mould [not shown] to eliminate or expel air from the cavity and consolidate the plurality of layers of fibers and the spar element 60a. Upon sealing the plurality of layers of fibers and the spar element 60a, a resin may be infused through the cavity created by the vacuum bag 100 and the mould. The resin infused may flow through the cavity and wet the plurality of layers of fibers. Also, the infused resin flows between the plurality of layers of fibers and the spar element 60a. The infused resin is allowed to cure before the vacuum bag 100 is removed from the mould. This process is herein also referred to as resin infusion process. In a preferred embodiment, the mould of the first shell half struc ture 32a and the second shell half structure 32b may be closed and the resin may be in fused to the plurality of layer of fibers and the spar element 60a and the resin is allowed to cure. In this condition, sealing flanges of the mould when closed together may be con figured to act as vacuum bag to aid in resin infusion. The above-described process ensures that the spar element 60a is formed as an integral part of the first shell half structure 32a of the root end segment 32 of the blade 28. The spar element 60a may be adhered to the first shell half structure 32a of the blade 28 without the use of conventional adhesive bonds. It should be understood that the spar element 60a may also be positioned on the second shell half structure 32b of the root end segment 32 of the blade 28 and may be adhered to the second shell half structure 32b. Positioning of the spar element 60a on the first shell half structure 32a should by no means be construed as a limitation of the present invention.

In an embodiment of the disclosure, the spar element 60a may be adhered to at least one of the first shell half structure 32a and the second shell half structure 32b on the root end segment 32 that may be prefabricated. The method of adhering the spar element 60a to the prefabricated blade 28 is substantiated hereinbelow. At least one of the first shell half structure 32a or the second shell half structure 32b of the root end segment 28 may be placed in the mould. The spar element 60a is positioned over at least one of the first shell half structure 32a or the second shell half structure 32b which is prefabricated. In the present invention and for ease of substantiating, the spar element 60a may be considered to be placed on the first shell half structure 32a of the root end segment 32 of the blade 28. A portion of the spar element 60a which may come in contact with the first shell half structure 32a may be defined with a flow path. The flow path may be configured to facil itate flow of the resin between a portion of the first shell half structure 32a at which the spar element 60a is positioned and the spar element 60a. In an embodiment, the flow path may be created by using fluid flow media such as but not limiting to fiber mats or any other suitable means. Once the spar element 60a is positioned over the first shell half structure 32a, the resin is infused through the flow path defined on the portion of the spar element 60a and is allowed to cure. The spar element 60a may be adhered to the first shell half structure 32a upon complete curing of the resin. In an embodiment, the spar element 60a may be adhered to a spar cap of the blade 28. The spar element 60a may be adhered to the spar cap by resin infusion process. The said process eliminates the use of conven tional adhesive bonds which lead to high concentrated loads. In an embodiment, the resin may include a polyester compound such as but not limiting to an unsaturated polyester compound. In an embodiment, the resin used for infusion in the present disclosure is at least one of vinyl ester or epoxy resin. In some embodiment and as illustrated in FIG.8D, each of the two halves of the spar element 60a may be positioned on each of the first shell half structure 32a and the second shell half structure 32b [illustrated in dotted lines] of the wind turbine blade 28. For ex ample, a first half of the spar element 60a may be positioned on the first shell half struc ture 32a and a second half of the spar element 60a may be positioned on the second shell half structure 32b. In an embodiment, the two halves of the spar element 60a may be positioned at a predetermined position on the first shell half structure 32a and second shell half structure 32b. The pre-determined position described herein above may be proximal to the chord-wise joint 34 on the first and second shell half structures 32a and 32b. In some embodiments, predetermined position may be spar cap region in the wind turbine blade 28. The surface of the two halves of the spar element 60a that may come in contact with the shell 32a and 32b may be defined with a flow path. Once the two halves of the spar element 60a are placed over the respective shells 32a and 32b, resin may be infused in between the shells 32a and 32b and the two halves of the spar element 60a. The resin may be infused through the flow path defined on each of the two halves of the spar ele ment 60a. The infused resin may be subsequently allowed to cure, thereby adhering the two halves of the spar element 60a to the respective shells 32a and 32b. In another em bodiment, the two halves of the spar element 60a may be positioned over spar caps. Each of the two halves of the spar element 60a may be adhered to the respective spar caps by resin infusion process. Once the resin is cured and the each of the two halves of the spar element 60a is adhered to the respective spar caps, the spar caps are positioned on the first shell half structure 32a and second shell half structure 32b at a pre-determined position. The spar caps may be adhered to the first shell half structure 32a and second shell half structure 32b by the resin infusion process. Further, the two halves of the spar element 60a may be adhered to one another by any conventional joining process including but not limiting to adhesive bonding.

In an embodiment, as shown in Fig. 12, an end opposite to the receiving section 60 of the spar element 60a may be adhered or joined to a shear web 102 on the root end segment 32 of the wind turbine blade 28. The shear web 102 may be positioned at a substantially central portion on at least one of the first shell half structure 32a or the second shell half structure 32b. The shear web 102 may extend along the length blade 28 from the root end and up-to the spar element 60a. In some embodiments, the shear web 102 may be connected to at least one of the first shell half structure 32a or the second shell half struc ture 32b by at least one of adhesive bond or resin infusion process. As depicted in FIG.12. the end of the spar element 60a opposite to the receiving section may be connected to the shear web 102 of the blade 28 by the resin infusion process. The resin may be infused in a space between the end of spar element 60a and the shear web 102.

Typical ways of joining the shear web 102 with the spar element 60a are shown in FIG(s). 13 (a) to 14 (d). According to some embodiments of the present invention, the spar ele ment 60a may be defined with an extending portion on the end opposite to the receiving portion 60. The extending portion may be configured to connect to the shear web 102 of the blade 28. FIG(s). 13 (a) to (d) shows the extended portion of the spar element 60a that may be connected with the shear web 102 of the root end segment 32. As shown in FIG.13 (a), the root end segment 32 of the blade 28 may include multiple shear web 102 extend ing parallelly from the root region of the blade up to the spar element 60a. The parallelly running shear webs 102 are then adhered to the spar element 60a by the resin infusion process, thus forming a co-infused joint between the spar element 60a and the shear web 102. According to another embodiment of the present invention, as shown in FIG. 13 (b) and 13 (c), the root end segment 32 of the blade 28 may include a single shear web 102 extending from the root region of the blade 28 to the spar element 60a. The single shear web may be adhered to the spar element 60a by a Y-shaped joint member as shown in FIG.13 (b). Also, as shown in FIG.13c, the shear web 102 may extend into a portion of the spar element 60a. In both cases i.e. embodiments according to FIG(s) 13 (b) and 13 (c), the resin may be infused between the spar element 60a and the shear web 102 to form the co-infused joint. An even further embodiment of the present invention is shown in FIG. 13 (d), here the ends of the spar element 60a may be abutted against the shear web 102 and the resin may be infused between the shear web 102 and the spar element 60a. In some embodiments and as shown in FIG.8D, the spar element 60a may be defined with a scarf region. The scarf region may be configured to be connected to the shear web 102 and the spar cap by a resin infusion process. In a preferred embodiment, the resin may be infused in the gap formed between the shear web 102 and the spar element 60a [i.e. the process of joining the shear web and the spar element according to FIG.12 and 13]. A flow media such as but not limiting to fiber mat may be positioned in the gap between the shear web 102 and the spar element 60a. The resin may then be infused through the flow media to the gap and may be allowed to cure. Upon curing the resin bonds both the spar element 60a and the shear web 102 together to obtain a resin infused joint.

In some embodiments, the shear web 102 may be directly connected to the end of the end of the spar element 60a as shown in FIG(s) 14 (a) to (d). As shown in FIG.14 (a) and 14 (b), at least one corner of the end of the spar element 60a may be chamfered. The cham fered portion on the spar element 60a may accommodate the ends of the shear web 102. The ends of the shear web 102 that may be connected to the spar element 60a may also be counter chamfered. The resin may be infused in the space between the chamfered por tion of the shear web 102 and the spar element 60a to adhere the shear web 102 to the spar element 60a. According to another embodiment of the present invention as shown in FIG(s) 14 (c) and 14 (d), the shear web 102 of the root end segment 32 may be abutted against the end of the spar element 60a. The resin may be infused in space between the shear web 102 and the spar element 60a, thereby adhering the spar element 60a to the shear web 102 upon curing of the resin. However, the above methods should not be con strued as a limitation to the present invention.

Upon positioning the spar element 60a, shear web 102 and other blade components on the at least one of the first shell half structure 32a, the second shell half structure 32b may be adhered to the first shell half structure 32a. In an embodiment, before adhering the second shell half structure 32b to the first shell half structure 32a, the surfaces of the spar element 60a, and other blade components facing the second shell half structure 32b may be applied with adhesives. Subsequently, before lowering the second half shell structure 32b on to the first half shell structure 32a, adhesive is applied over the leading edge and the trailing edge. Once the adhesive is applied on the leading edge and the trailing edge the second half shell structure 32b may be lowered over the first shell half structure 32a. Upon bonding the first shell half structure 32a and second shell half structure 32b, the adhesive may be allowed to cure to obtain the root end segment 32 of the blade 28. Fur ther, the blade 28 is removed from the mould and the excess material may be trimmed. In some embodiments, the spar elements 60a, shear web 102 and other blade components may be adhered by the resin infusion process on at least one of the shells 32a and 32b which undergoes more pressure during operation. In an embodiment, the said resin infusion method may also be used to adhere beam structure 40 in the tip end segment of the blade 30.

In an embodiment, the use of resin infusion process for adhering the spar element 60a may reduce the concentrated load at the chord-wise joint 34 of blade 28 unlike the con ventional adhesive bond process. The structural properties of blade at the chord- wise joint doesn’t change by the use of resin infusion process which is not in case of the conven tional adhesive bonds. The resin infused joints may significantly increase potential strength of tip end segment 30 of the blade 28. Also, the elimination of adhesive bonds reduces the blade mass, cost and significantly increases the robustness and reliability. Also, use of resin infusion process does not limit the design feature unlike the adhesive bonds.

The invention is not limited to the embodiments described herein and may be modified or adapted without departing from the scope of the present invention.

Exemplary embodiments of the present disclosure are set out in the following items:

1. A method of manufacturing a shell of a wind turbine blade (28), the method com prising: laying one or more shell or spar fibers, on a surface of mould to form at least a portion of the blade shell; positioning a spar element (60a) at pre-defined position on the one or more layers of fiber; covering a vacuum bag (100) over the one or more layers of fiber and the spar element (60a) to seal the spar element (60a) and the one or more layers of fibers; and infusing resin through the one or more layers of fiber and the spar element (60a) and subsequently curing the same to obtain the shell (32a or 32b), wherein the spar element (60a) adheres to the shell (32a or 32b) upon curing the infused resin.

2. The method according to claim 1, wherein the spar element (60a) is a spar beam receiver section or a portion of receiver section. The method according to any of claims 1-2, wherein the resin includes a polyester compound, preferably at least one of a vinyl ester or epoxy resins. The method according to any of claims 1-3, wherein the one or more layers of fibers on the mould are glass fibers and the one or more layers of fibers are in form of at least one of fabrics, prefabricated structure or loose fibers. The method according to any of claims 1-4 comprises positioning a shear web (102) at a substantially central portion of the shell (30 and 32), wherein the shear web (102) extends along length of the shell and up-to the spar element (60a). The method according to claim 5, wherein an end of the spar element (60a) is connected to the shear web (102). The method according to claim 6 comprises joining the end of spar element (60a) and the shear web (102) by resin infusion process. A method for joining a spar element to a wind turbine blade (28), the method comprises: positioning the spar element (60a) on a shell (32a or 32b) or spar cap of the wind turbine blade (28), wherein a portion of the spar element (60a) in contact with the shell or spar cap is defined with a flow path; and infusing resin between the spar element (60a) and the shell (32a or 32b) or the spar cap through the flow path and subsequently curing the same to adhere the spar element (60a) to the shell (32a or 32b) or spar cap of the wind turbine blade (10). The method according to claim 8, wherein the resin includes a polyester com pound, preferably at least one of a vinyl ester or epoxy resins. The method according to any of claims 8-9 comprises positioning a shear web (102) at a substantially central portion shell, wherein the shear web (102) extends along length of the shell and up-to the spar element (60a). The method according to claim 10, wherein an end of the spar element (60a) is connected to the shear web (102). The method according to claim 11 comprises joining the spar element (60a) and the shear web (102) of the wind turbine blade by resin infusion process. A method for manufacturing a root end segment (32) of the wind turbine blade (10), the method comprising: forming a first shell half structure (32a) and a second shell half structure (32b) separately in a mould; joining a spar element (60a) to at least one of the first shell half structure (32a) and the second shell half structure (32b) by resin infusion process in the mould; positioning a shear web (102) at a substantially central portion of the first shell half structure (32a) and the second shell half structure (32b), wherein the shear web (102) extends in a spanwise direction up-to the spar element (60a); joining an end of the spar element (60a) and the shear web (102) by resin infusion process; and joining and sealing the first shell half structure (32a) and a second shell half structure (32b) to obtain the root end segment (32) of the wind turbine blade (10). The method according to claim 13, wherein a first half of the spar element (60a) is bonded to the first shell half structure (32a) and a second half of the spar element (60a) is bonded to the second shell half structure (32b). The method according to any of claims 13-14 comprises adhering the first half of the spar element (60a) to the second half of the spar element (60a) before joining of the first shell half structure (32a) and the second shell half structure (32b). The method according to any of claims 13-15, wherein the spar element (60a) is defined with an extending portion on an end opposite to receiving section (60), the extending portion is configured to connect to the shear web (102). 17. The method according to any of claims 13-16, wherein the first shell half structure (32a) and the second shell half structure (32b) are formed by laying plurality of layers of fiber in the mould, infusing resin and subsequently curing the resin.

18. The method according to any of claims 13-17, wherein the resin includes a poly ester compound, preferably at least one of a vinyl ester or epoxy resins.

19. The method according to any of claims 17-18, wherein the one or more layers of fibers on the mould are glass fibers.

20. A wind turbine blade (10) comprising a shell and a spar element (60a) adhered to the shell through the resin infusion process as claimed in any of the previous claims.

List of reference numerals

10 Wind turbine

12 Tower

14 Support surface

16 nacelle

17 Blade tip

18 Generator

19 Blade root end

20 Gear box

22 Rotor

24 Rotor shaft

26 Rotatable hub

28 Wind turbine blade or Rotor blade 30 Tip end segment

32 Root end segment

32a First shell half structure of root end segment 32b Second shell half structure of root end segment

32c Airfoil region d Transition region e shoulder Chord wise joint Internal support structures Arrow Beam structure Shear web on tip end segment and 46 Spar cap Chord wise member Pin Joint slot Span -wise extending pin Receiving end Span- wise pin joint slot Chord-wise pin joint slot Receiving section a Spar element b Extended portion of the spar element Chord-wise extending pin Spar structures 0 Vacuum bag 2 Shear web for root end segment and configuration of shear web3 Mould 3a and 103b outer and inner surface of the mould respectively