JP6644649B2 - Windmill blade - Google Patents

Description

  The present invention relates to a wind turbine blade.

Conventionally, various windmills have been constructed for the purpose of wind power generation and the like.
As the wind turbine, a horizontal axis wind turbine whose rotation axis is installed in parallel with the wind direction and a vertical axis wind turbine whose rotation axis is installed in a direction crossing the wind direction are known.

  As this vertical axis windmill, a type in which a metal blade is attached to a rod-shaped support extending radially from the rotation axis is known, and a blade used for the windmill is a metal plate having a hollow blade. There is a known type provided with a shell member formed in a mold (see Patent Document 1 below).

JP 2008-101536 A

Wind turbine blades are required to be lightweight.
2. Description of the Related Art In freight cars and small boats, weight reduction is achieved by replacing a portion made of metal with a fiber reinforced resin material called FRP.
Therefore, it is conceivable to adopt, for example, a shell member formed of a fiber-reinforced resin sheet containing a fiber and a resin instead of a metal-made blade member for a windmill blade required to be reduced in weight. .

By the way, wind turbine blades are usually bent or twisted by wind force, so that local stress concentration is likely to occur.
The fiber reinforced resin sheet has lower bending rigidity than a general metal plate having the same thickness.
For this reason, in the wind turbine blade, if the shell member is simply formed of a fiber-reinforced resin sheet, stress concentration when bending or twisting occurs may be more remarkable than that of a metal blade.
That is, the conventional wind turbine blade has a problem that it is difficult to achieve both strength and light weight.

  An object of the present invention is to solve such a problem, and an object of the present invention is to provide a windmill blade excellent in strength and lightness.

  In order to solve the above-mentioned problems, the present inventor has studied diligently, and stress concentration of the shell member is easily generated in the fixing portion fixed to the support, and by filling the resin foam in the fixing portion. The inventors have found that stress concentration can be reduced, and have completed the present invention.

That is, in order to solve the above problems, the present invention is a wind turbine blade fixed to a rod-shaped support tool extending radially from the rotation axis of a vertical axis wind turbine, and is formed by a fiber reinforced resin sheet containing fibers and resin. with a hollow shell member has a fixed portion that the shell member is fixed to the support, in the interior of the shell member provided with filling portions of the resin foam is filled, and, the shell member inside the provided cavity resin foam is not filled yet, the proportion of the filler portion occupying the internal volume of the shell member does not exceed 10% by volume or more, and the inside of the fixing part the filling unit To provide wind turbine blades.

The blade for a windmill according to the present invention is excellent in strength because stress concentration hardly occurs because the inside of the fixing portion fixed to the support is a filling portion.
The windmill blade of the present invention is excellent in lightness because the shell member is made of a fiber-reinforced resin sheet.
That is, according to the present invention, a windmill blade excellent in strength and lightness can be provided.

It is the schematic perspective view which showed the principal part of the vertical axis windmill. FIG. 2 is an internal structural view of the wind turbine blade (a sectional view taken along line II-II in FIG. 1). The figure which showed the internal structure of the blade for windmills of another aspect from FIG. The figure which showed the simulation result in an Example.

Hereinafter, a windmill blade according to an embodiment of the present invention will be described.
First, a wind turbine for wind power generation provided with the wind turbine blade according to the present embodiment will be described with reference to FIG.

FIG. 1 is a diagram showing a wind turbine main body 100 of a vertical axis wind turbine. As shown in the figure, the vertical axis wind turbine according to the present embodiment is a gyromill wind turbine.
That is, the windmill main body 100 includes a rotating shaft 10 extending in the vertical direction H, a rod-shaped support 20 radially outwardly extending radially from an upper end of the rotating shaft 10, and a tip end of the support 20. A fixed wind turbine blade 30 (hereinafter, also simply referred to as “blade 30”) is provided.
The windmill main body 100 is configured so that when the blade 30 receives the wind W from a direction intersecting with the direction in which the rotating shaft 10 extends, the blade 30 orbits around the rotating shaft 10 by the wind force. .
The vertical axis wind turbine is configured such that the blade 30 moves in a direction R (hereinafter, also referred to as a “circumferential direction R”) orbiting around the rotation axis 10, and is connected to the blade 30 via a support 20. The rotating shaft 10 rotates around the axis, and the rotating motion of the rotating shaft 10 is used to drive a generator (not shown) to generate electric power.

  The wind turbine main body 100 of the present embodiment includes a plurality of blades 30, and the plurality of blades 30 are arranged on the same circumference around the rotation shaft 10 when viewed in the axial direction of the rotation shaft 10, and They are arranged at substantially equal intervals in the circumferential direction R.

One end of the support 20 is fixed to the rotating shaft, and the blade 30 is fixed to the other end.
The blade 30 of the present embodiment, which is fixed to the rotation shaft by the support 20, has a long plate shape and is arranged in parallel with the rotation shaft.
That is, the blade 30 of the present embodiment is disposed on the windmill main body 100 such that the longitudinal direction is the vertical direction H, the lateral direction is the circumferential direction R, and the thickness direction is the radial direction D.
The blade 30 of the present embodiment is connected to the support 20 at the center in the longitudinal direction (vertical direction H).

The blade 30 is not particularly limited in its wing shape and the like, and may employ a Zhukovsky wing or a NACA wing.
The blade 30 has a hollow shell member 31 as shown in FIG.
The shell member 31 includes a first wall portion 311 and a second wall portion 312 which face each other in a thickness direction (radial direction D) via a hollow portion, and the first wall portion 311 is separated from the second wall portion 312. Are also located on the rotating shaft side.
The support 20 penetrates the first wall portion 311 and the second wall portion 312, and has a tip portion projecting radially outward from the blade 30.
The portion of the shell member 31 that penetrates the support tool 20 is a fixing portion 32 to which the support tool 20 is fixed.

Here, when the wind W is received, stress is applied to the blade 30 fixed to the support 20 in a direction of bending around the fixed portion.
For example, when the blade 30 is on the windward side of the rotating shaft 10, both ends in the vertical direction are easily deformed by the wind force in a direction approaching the rotating shaft 10.
However, when the blade 30 is rotated and moved to the leeward of the rotating shaft 10 thereafter, both ends in the vertical direction are easily deformed in a direction away from the rotating shaft 10.
Accordingly, when the blade 30 rotates in response to the wind W, the blade 30 repeatedly bends inward and outward around the fixed portion 32.
When the blade 30 is rotated at high speed by receiving a strong wind, both ends in the vertical direction are easily deformed in a direction away from the rotating shaft 10 by centrifugal force.
For this reason, it is preferable that the blade 30 be provided with measures for preventing breakage or the like in the vicinity of the fixing portion 32.

As the above countermeasure, one blade is fixed to the rotating shaft by a plurality of supports, and a plurality of fixing portions are provided in the longitudinal direction of the blade 30 by a plurality of supports arranged in the vertical direction, or a shell member is simply provided. For example, it is conceivable to increase the thickness of the base member 31 for reinforcement.
However, these countermeasures are not sufficiently preferable for making the windmill main body 100 exhibit lightness.
Therefore, in the present embodiment, the resin foam 40 is provided inside the fixing portion.
The resin foam 40 is in contact with the shell member 31 from the inside, and presses the first wall portion 311 and the second wall portion 312 from the inside.
Therefore, when the first wall portion 31 and the second wall portion 312 are subjected to a stress that causes the fixing portion 32 to bend, the resin foam 40 suppresses the occurrence of large deformation.
In addition, since the applied stress is diffused through the resin foam 40, stress concentration hardly occurs in the blade 30 of the present embodiment.
That is, since the blade 30 of the present embodiment includes the filling portion filled with the resin foam 40, local stress concentration in the fixing portion 32 hardly occurs even when the blade 30 is bent as described above.

At a position distant from the fixing portion 32, stress concentration is less likely to occur in the normal operation of the vertical axis wind turbine than in the fixing portion 32, so that the need to fill the resin foam 40 is low.
Therefore, in the blade 30 of the present embodiment, as illustrated in FIG. 2, it is preferable to provide a hollow portion 50 in which no resin foam or the like is filled inside the shell member 31 in consideration of lightness.
Moreover, it is preferable that the hollow portions 50 are provided at both ends in the longitudinal direction of the shell member.
Thus, both ends of the blade 30 can be reduced in weight, so that the centrifugal force generated at both ends when the blade 30 rotates at a high speed can be reduced by the existence of the cavity 50.

The filling portion filled with the resin foam 40 and the size of the hollow portion 50 formed in the shell member as an extra space of the filling portion are not particularly limited, but the resin foam 40 is When the inner volume of the shell member 31 is set to V (cm ³ ), the shell member 31 is preferably filled at a rate of V / 10 (10% by volume) or more, and filled at a rate of V / 5 (20% by volume) or more. It is more preferable that the filling is performed at a ratio of V / 2.5 (40% by volume) or more.
Further, the filling ratio of the resin foam 40 is preferably V (100% by volume) or less, more preferably 0.95V (95% by volume) or less, and 0.9V (90% by volume) or less. It is particularly preferred that there is.
That is, when the gaps 50 are provided at both ends of the blade 30, the ratio is preferably 2.5% by volume or more (5% by volume or more in total), and preferably 5% by volume or more (10% by volume or more in total). ) Is more preferable.
The resin foam 40 has an average thickness at the center in the longitudinal direction (thickness in a state accommodated in the shell member) as t (mm) and a dimension in the longitudinal direction of the blade 30 as L (mm). It is preferable that these have a shape such that the ratio (L / t) is 1 or more and 1000 or less, more preferably 5 or more and 500 or less, and particularly preferably 10 or more and 200 or less.
Note that “t” is a value obtained by dividing the cross-sectional area at the central portion in the longitudinal direction of the resin foam 40 by the circumferential dimension, and “L” is obtained from the longest dimension of the resin foam 40 in the longitudinal direction. Value.

The shell member 31 of the present embodiment is formed of a fiber reinforced resin sheet containing fibers and resin in consideration of the lightness of the blade 30.
Examples of the fiber contained in the fiber-reinforced resin sheet include glass fiber, carbon fiber, aramid fiber, polyvinyl alcohol fiber, vinyl chloride fiber, acrylic fiber, polyester fiber, polyurethane fiber, polyethylene fiber, polypropylene fiber, polystyrene fiber, and acetate. Fibers and the like can be mentioned.

Examples of the resin constituting the fiber reinforced resin sheet together with the fibers (hereinafter also referred to as “matrix resin”) include a thermoplastic resin and a thermosetting resin.
Examples of the thermoplastic resin include a polyethylene resin, a polypropylene resin, a polystyrene resin, a polybutadiene resin, a styrene-butadiene resin, a polyacetal resin, a polyamide resin, and a polycarbonate resin.
Examples of the thermosetting resin include an unsaturated polyester resin, an acrylic resin, a vinyl ester resin, an epoxy resin, a urethane resin, a phenol resin, and a silicone resin.

As the resin foam to be filled in the shell member 31 formed of such a fiber reinforced resin sheet, for example, an acrylic resin foam, a polyester resin foam, a styrene resin foam, etc. exhibit excellent strength. Is preferred in that
In addition, the resin foam preferably has an apparent density of 0.04 g / cm ³ or more and 0.5 g / cm ³ or less.

The acrylic resin that forms the acrylic resin foam contains methyl methacrylate, (meth) acrylic acid, and styrene as monomer units because it is easy for the resin foam to exhibit excellent strength and lightweight properties. Preferably, one or both of maleic anhydride and methacrylamide are optionally contained as the monomer units, and the monomer units are preferably contained in the following proportions.

(A) Methyl methacrylate: 35 to 70% by mass
(B) (meth) acrylic acid: 14 to 45% by mass
(C) Styrene: 10 to 20 mass% (D) Maleic anhydride: 0 to 10 mass%
(E) Methacrylamide: 0 to 10% by mass

In the acrylic resin, the content of monomer units other than (A) to (D) is more preferably 20% by mass or less, particularly preferably 10% by mass or less, and more preferably 5% by mass or less. Particularly preferred.

  The polyester-based resin forming the polyester-based resin foam is preferably selected from polyethylene terephthalate, polyethylene naphthalate, and a crosslinked product thereof. The polyester-based resin is preferably a resin obtained by reacting a mixed resin containing 1% by mass to 60% by mass of polyethylene naphthalate and 40% by mass to 99% by mass of polyethylene terephthalate with a crosslinking agent.

  The styrene-based resin forming the styrene-based resin foam is preferably a styrene- (meth) acrylate-maleic anhydride copolymer. It is preferable that the styrene resin foam contains a styrene- (meth) acrylate-maleic anhydride copolymer and polymethyl methacrylate. The content of polymethyl methacrylate is preferably from 10 parts by mass to 500 parts by mass, and more preferably from 20 parts by mass to 450 parts by mass, based on 100 parts by mass of the styrene- (meth) acrylate-maleic anhydride copolymer. Parts by weight or less, more preferably 30 parts by weight or more and 400 parts by weight or less.

  The styrene- (meth) acrylate-maleic anhydride copolymer has a total content of styrene monomer units, (meth) acrylate ester monomer units and maleic anhydride monomer units of 100% by mass. In this case, the content of the styrene monomer unit is preferably from 30% by mass to 70% by mass, more preferably from 40% by mass to 65% by mass, and more preferably from 45% by mass to 60% by mass. It is particularly preferred that there is. Further, when the total content of the styrene monomer unit, the (meth) acrylate monomer unit and the maleic anhydride monomer unit is 100% by mass, the (meth) acrylate ester The content of the monomer unit is preferably from 10% by mass to 30% by mass, more preferably from 13% by mass to 28% by mass, and particularly preferably from 15% by mass to 25% by mass. preferable.

  The resin foam 40 may be any of a bead foam molded article in which a plurality of resin foam particles are molded in a mold, an extruded foam molded article, a bulk foam molded article in which a non-foamed resin mass is foamed in a mold, and the like. However, it is preferably a bead foam molded article in that a foam having a high expansion ratio and high strength is easily obtained.

  The bead foam molding is also advantageous in that a complicated shape can be easily provided to the resin foam 40.

To describe this point in detail, in the blade 30 of the present embodiment, both sides (one and the other in the longitudinal direction of the blade 30) of the filling portion filled with the resin foam 40 are hollow portions 50.
Therefore, the blade 30 of the present embodiment easily moves the resin foam 40 in the shell member, and the resin foam 40 easily shifts in position.
Therefore, it is preferable to provide a shape that fits unevenly between the resin foam 40 and the shell member 31.
It is preferable that the resin foam 40 is a bead foam molded body in that the resin foam 40 having such a shape can be easily formed.

  The resin foam 40 is also preferably a bead foam molded body in that it can be easily composited with other members.

To describe this point in detail, for fixing the support 20 and the shell member 31, for example, the support is a round bar or a pipe having a screw thread on the outer peripheral surface, and the first wall 311 or the first wall 311 is fixed by a nut or a washer. A method of sandwiching the two wall portions 312 from inside and outside can be applied.
More specifically, the fixing between the support 20 and the shell member 31 can be performed, for example, by performing the following steps (a) to (f).
(A) The first wall 311 and the second wall 312 are provided with holes for allowing the support 20 to pass therethrough.
(B) A tube (such as a resin pipe or the like) having a length corresponding to the distance between the inner surface of the first wall portion 311 and the inner surface of the second wall portion 312 and having an inner diameter through which the support 20 can be inserted. Prepare a metal pipe).
(C) One of the openings at both ends of the tubular body is made to correspond to the hole in the first wall portion 311 and the other is made to correspond to the hole in the second wall portion 312, and is housed inside the shell member 31, A hole penetrating the blade 30 in the thickness direction is formed.
(D) A support 20 having a screw thread is prepared, and the screw thread appears outside the first wall 311 and the second wall 312 when the blade 30 is penetrated through the hole. Then, a support 20 is prepared.
(E) At least two nuts that can be screwed to the support 20 are prepared, and one of them is fitted to the support 20 and the support 20 is passed through the hole from the side of the first wall 311 and the distal end is made the second. It protrudes from the hole of the two wall portions 312.
(F) The other nut is fitted to the support 20 protruding from the second wall 312, and the two nuts are tightened toward the tube, and the first wall 311 of the shell member 31 and the second nut are tightened by the nut and the tube. The two wall portions 312 are sandwiched from inside and outside.

  Here, when the resin foam 40 is a bead foam molded body, for example, a fixing member (for fixing the support 20 and the blade 30 by sandwiching the first wall 311 and the second wall 312 from inside and outside). The above-mentioned tube body and the like can be integrated.

  The above method is merely an example, and the fixing method between the support 20 and the blade 30 can be implemented by various methods other than the above example.

In addition, as a method of manufacturing the blade 30 for the vertical axis wind turbine of the present embodiment, for example, the following method is used.
First, a resin foam for forming a filling portion is prepared.
Then, separately from this, a pair of molds is prepared in which an internal space corresponding to the windmill blade is formed when the mold is closed.
A liquid or gel-like coating material is applied to the molding surfaces of the pair of molding dies, and is stretched by a roller so that air does not enter the molding surfaces.
Next, a half body which becomes a shell member by being united is manufactured using a mold on one side.
One example is a hand lay-up molding method.
Specifically, a fiber sheet is placed in a molding die, and the fiber sheet for reinforcement is impregnated with a thermosetting resin serving as a matrix resin.
Further, the steps of similarly arranging the fiber sheets and impregnating the thermosetting resin are repeated to form a laminated structure of a plurality of fiber reinforced resin materials in the thickness direction of the half body.

The same operation is performed on the other mold, and another half body is manufactured.
At this time, when a thermosetting resin or a thermoplastic resin is used as the matrix resin, the mold may be heated appropriately.
If a reaction-curable resin that cures at room temperature is used as the matrix resin, heating of the mold is not particularly required.
It is not necessary to impregnate the thermosetting resin every time a fiber sheet is laid one layer at a time, and if air is unlikely to remain on the fiber sheet, after laminating a plurality of fiber sheets, the thermosetting resin The resin may be impregnated at one time.

Further, after the forming material of the half body is accommodated in the forming die, if necessary, the forming material arranged in the forming die may be pressed in the thickness direction.
In that case, excess resin can be eliminated by pressurization, and the finally formed shell member can have high strength.
When a shell member having excellent strength is formed by applying the pressure, for example, another mold having a convex portion corresponding to the concave shape of the mold is fitted to the mold containing the forming material, and two What is necessary is just to pressurize with the forming material interposed between the molds.
The pressurization can also be performed by an autoclave method without using another mold.
Examples of the autoclave method include the following methods.

(Method for producing shell member (half-split body) by autoclave method)
A plurality of fiber-reinforced resin sheets provided with a plain-woven glass fiber sheet are laminated so as to be in contact with the molding surface of the mold, and a laminate (for example, five layers) is formed on the molding surface.
Here, such a laminate is used as a material for forming a half body.
A release film (for example, manufactured by AIRTECH, trade name "WL5200B-P") and a breather cloth (for example, AIRTECH, trade name "AIRWEAVE N4") having a through-hole so as to cover the entire mold. Are sequentially laminated.
For the release film, for example, a film formed from a tetrafluoroethylene-ethylene copolymer film and having a large number of through-holes that can penetrate between both surfaces and allow the resin exuding from the forming material to pass therethrough. Can be used.
The breather cloth may be formed of, for example, a non-woven fabric composed of polyester resin fibers, and may be a material that can be impregnated with the resin.
A bagging film (for example, product name “WL7400” manufactured by AIRTECH) is put on the breather cloth, and a sealant tape (for example, AIRTECH Co., Ltd.) is used as a sealing material between an outer peripheral portion of the bagging film and a mold facing the bagging film. (Trade name: GS43MR), and the material for forming the half body is sealed with a bagging film.
As the bagging film, for example, a film made of a polyamide resin film can be used.
In addition, a bagging film having a back valve (for example, trade name “VAC VALVE 402A” manufactured by AIRTECH) partly disposed therein can be used.

Next, the mold is supplied into an autoclave, the back valve is connected to a vacuum line, and the pressure is reduced to, for example, 0.10 MPa.
This pressure reduction is performed continuously thereafter.
Thereafter, the temperature inside the autoclave is raised to 90 ° C. at a rate of 4 ° C./min, for example, while sucking and removing air existing in the material for forming the half-split body. Is heated to 90 ° C. for 90 minutes (preliminary heating step).

Thereafter, the inside of the autoclave is pressurized to, for example, a gauge pressure of 0.1 MPa to apply a pressing force to the material for forming the half body, and the inside of the autoclave is heated to, for example, 130 ° C. at a heating rate of 4 ° C./min. The temperature is raised and the material is heated to 130 ° C. for 60 minutes.
Thereafter, the inside of the autoclave is cooled. For example, when the inside of the autoclave reaches 60 ° C., the pressure in the autoclave is released to return to the atmospheric pressure, the half is taken out, and cooled to room temperature.
By such an operation, a half body of the shell member can be obtained.
The other half is manufactured in the same manner, and the obtained two can be combined to form a shell member of a windmill blade.

(Production of blade for windmill)
The cured half body is placed in a mold, and after the adhesive is put in, the resin foam is placed.
The other mold is also accommodated in a half-piece with the adhesive applied thereto, and the two molds are closed and adhered.
At this time, an unsaturated polyester resin or the like can be used as an adhesive for bonding the shell member and the resin foam.
When producing a blade having excellent strength, the unsaturated polyester resin is preferably used in a state of being impregnated in a fiber sheet. For example, the unsaturated polyester resin is impregnated in a glass chipped mat having a basis weight of 380 g / m ² and a shell member. It can be used for bonding with resin foam.
Thereby, a vertical axis wind turbine as shown in FIG. 2 can be manufactured.

The wind turbine blade of the present invention is not limited to the above-mentioned examples at all, and conventionally well-known items other than the above-described technical items can be appropriately adopted.
For example, in this embodiment, the case where the vertical axis wind turbine is a gyromill wind turbine is illustrated, but the blade for a wind turbine of the present invention may be used for a Darrieus wind turbine or the like.

Further, in the above description, the case where the support 20 having a straight rod shape as a whole is used is illustrated. For example, the support may be as shown in FIG.
The support tool 20 'illustrated in FIG. 3 has a rod portion 21' radially outwardly extending from the rotation shaft in a radial direction, and a flange portion 22 'extending outward from the tip of the rod portion 1'.
In the embodiment illustrated in FIG. 3, a plate-shaped member 23 ′ arranged to face the flange portion 22 ′ is further used, and a windmill blade is provided between the plate-shaped member 23 ′ and the flange portion 22 ′. The wind turbine blade 30 is fixed to the support 20 ′ by sandwiching the plate 30 and fastening the plate 23 ′ and the flange 22 ′ with fasteners 24 ′ such as bolts and nuts.
In the embodiment shown in FIG. 3, a fixing portion 32 fixed by the plate-like body 23 'and the flange portion 22' is provided on the wind turbine blade 30.
The inside of the fixing portion 32 is a filling portion as in the embodiment shown in FIG.
In addition, the blade 30 illustrated in FIG. 3 is common to the blade 30 illustrated in FIG. 2 in that the blade 30 illustrated in FIG.
Further, the present invention can be implemented in an embodiment other than that shown in FIG.

  Next, the present invention will be described in more detail with reference to examples, but the present invention is not limited thereto.

A simulation was performed on a blade having a hollow shell member formed of a 1 mm thick glass fiber reinforced resin sheet.
The simulation was performed with the center part in the length direction of the shell member as a fixed part, and when the fixed part was filled with the resin foam and not filled.
FIG. 4 shows the results of a simulation of how the blade displacement shows a distribution under an operating condition where the rotation axis has a rotation speed of 800 rpm.

FIG. 4A shows a case where the inside of the fixed portion of the shell member is a filling portion, and FIG. 4B shows a distribution of displacement when the inside of the shell member is not filled with the resin foam at all. It is represented by the shade of color.
As can be seen from the figure, in FIG. 4B, the dark portion is concentrated on the fixed portion, whereas in FIG. 4A, the dark portion is widely diffused.
That is, it can be seen from the results of FIG. 4 that the present invention provides a windmill blade excellent in strength and lightness.

10: rotating shaft, 20: support, 30: blade (blade for windmill), 31: shell member, 32: fixed part, 40: resin foam (filled part), 50: hollow part, 100: windmill main part

Claims (3)

A wind turbine blade fixed to a rod-shaped support extending radially from the rotation axis of the vertical axis wind turbine,
A hollow shell member formed by a fiber-reinforced resin sheet containing fibers and a resin, and the shell member has a fixing portion fixed to the support,
The interior of the shell member provided with filling portions of the resin foam is filled, and, in the interior of the shell member provided cavity resin foam is not filled further, the internal volume of the shell member the proportion of the filler portion occupying the is 10 vol% or more,
A blade for a windmill, wherein the inside of the fixed portion is the filling portion.   The shell member has a long plate shape, and is attached to the support so as to extend along the rotation axis direction. A central portion in the length direction is the fixing portion, and the inside of the fixing portion is the filling portion. The wind turbine blade according to claim 1, which is a part. The wind turbine blade according to claim 2, wherein the hollow portions are provided at both ends in the length direction .