Wind turbine rotor blade with access window

Abstract

The present invention relates to a wind turbine blade (10) comprising an aerodynamic shell (83) having an outer surface (84) forming at least part of an exterior surface of the wind turbine blade and an inner surface (85). An access window (80) extends through the shell (83). A panel (87) is arranged within a recessed portion (86) at the inner surface of the shell adjacent to the access window (80) for closing the access window (80).

Claims

1. A wind turbine blade, comprising: a profiled contour comprising a pressure side and a suction side, and a leading edge and a trailing edge with a chord having a chord length extending therebetween, the wind turbine blade extending in a spanwise direction between a root end and a tip end; an aerodynamic shell having an outer surface forming at least part of an exterior surface of the wind turbine blade, and an inner surface, an access window extending through the aerodynamic shell, wherein the aerodynamic shell comprises a recessed portion at the inner surface of the aerodynamic shell adjacent to the access window, a panel arranged within the recessed portion at the inner surface of the aerodynamic shell for closing the access window, and one or more sealing members arranged between the panel and the recessed portion at the inner surface of the aerodynamic shell.

2. The wind turbine blade of claim 1, wherein the recessed portion is provided in a stepwise design in that a thickness of the aerodynamic shell decreases in one or more discreet steps towards the access window.

3. The wind turbine blade of claim 1, wherein the panel has a width and a length, wherein the length of the panel exceeds the width of the panel.

4. The wind turbine blade of claim 1, wherein the panel comprises a top surface and a bottom surface, wherein at least part of the top surface is flush with the outer surface of the aerodynamic shell surrounding the access window.

5. The wind turbine blade of claim 1, wherein the panel comprises a central portion having a first thickness and an outer tongue portion having a second thickness, wherein the first thickness exceeds the second thickness, and wherein at least part of the outer tongue portion is arranged within the recessed portion at the inner surface of the aerodynamic shell.

6. The wind turbine blade of claim 5, wherein the recessed portion comprises a groove formed within the aerodynamic shell, and wherein the outer tongue portion of the panel is arranged in the groove to fasten the panel to the aerodynamic shell.

7. The wind turbine blade of claim 1, wherein the panel is substantially rectangular or elliptical.

8. The wind turbine blade of claim 1, wherein the panel is biased against the inner surface of the aerodynamic shell.

9. The wind turbine blade of claim 1, wherein the panel comprises a top surface and a bottom surface, wherein at least one first hook member extends from the bottom surface of the panel, wherein at least one second hook member extends from the inner surface of the aerodynamic shell, and wherein at least one elastic strap is fixed between the at least one first and second hook members extending from the bottom surface of the panel and from the inner surface of the aerodynamic shell for fastening the panel to the aerodynamic shell.

10. The wind turbine blade of claim 1, wherein the panel is rotatable from a first position to a second position in a plane substantially parallel to the outer surface of the aerodynamic shell surrounding the access window, wherein the first position allows for insertion of the panel into an interior space of the wind turbine blade, and wherein the second position allows for arranging the panel within the recessed portion at the inner surface of the aerodynamic shell for closing the access window.

11. The wind turbine blade of claim 10, wherein the rotation from the first position to the second position in a plane substantially parallel to the outer surface of the aerodynamic shell surrounding the access window is a rotation by 60 to 120 degrees.

12. The wind turbine blade of claim 1, wherein the panel abuts the recessed portion at the inner surface of the aerodynamic shell adjacent to the access window.

13. The wind turbine blade of claim 1, wherein the panel is separated from the recessed portion by the one or more sealing members.

14. A method, comprising: manufacturing an aerodynamic shell having an outer surface forming at least part of an exterior surface of a wind turbine blade and an inner surface, wherein an access window extends through the aerodynamic shell, and wherein the aerodynamic shell comprises a recessed portion at the inner surface of the aerodynamic shell adjacent to the access window; inserting a panel through the access window into an interior space of the wind turbine blade; arranging the panel within the recessed portion at the inner surface of the aerodynamic shell; arranging one or more sealing members between the panel and the recessed portion at the inner surface of the aerodynamic shell; and fixing the panel to the aerodynamic shell for closing the access window.

15. The method of claim 14, wherein inserting the panel through the access window into an interior space of the wind turbine blade further comprises: rotating the panel in a plane substantially parallel to the outer surface of the aerodynamic shell surrounding the access window, from a first position that allows for insertion of the panel into the interior space of the wind turbine blade, to a second position that allows for arranging the panel within the recessed portion at the inner surface of the aerodynamic shell for closing the access window.

16. The method of claim 14, wherein the rotation from the first position to the second position in a plane substantially parallel to the outer surface of the aerodynamic shell surrounding the access window is a rotation by 60 to 120 degrees.

Description

DESCRIPTION OF THE INVENTION

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

(2) FIG. 1 shows a wind turbine,

(3) FIG. 2 shows a schematic view of a wind turbine blade,

(4) FIG. 3 shows a schematic view of a cross-section of a wind turbine blade,

(5) FIG. 4 is a schematic cut-open view of a wind turbine blade,

(6) FIG. 5 is an enlarged view of the encircled section in FIG. 4, and

(7) FIGS. 6, 7 and 8 are perspective views of a spar structure,

(8) FIG. 9 is a partial perspective view of an access opening of a wind turbine blade,

(9) FIG. 10 is a perspective partial view of a wind turbine rotor blade,

(10) FIG. 11 is partial cross sectional view of a wind turbine rotor blade according to the present invention, taken along the line A-A in FIG. 10,

(11) FIG. 12 is a schematic top view of different panels according to the present invention, and

(12) FIG. 13 is a partial cross sectional view of a wind turbine rotor blade according to one embodiment of the present invention.

DETAILED DESCRIPTION

(13) FIG. 1 illustrates a conventional modern upwind wind turbine 2 according to the so-called Danish concept with a tower 4, a nacelle 6 and a rotor with a substantially horizontal rotor shaft. The rotor includes a hub 8 and three blades 10 extending radially from the hub 8, each having a blade root 16 nearest the hub and a blade tip 14 farthest from the hub 8. The rotor has a radius denoted R.

(14) FIG. 2 shows a schematic view of a wind turbine blade 10. The wind turbine blade 10 has the shape of a conventional wind turbine blade and comprises a root region 30 closest to the hub, a profiled or an airfoil region 34 farthest away from the hub and a transition region 32 between the root region 30 and the airfoil region 34. The blade 10 comprises a leading edge 18 facing the direction of rotation of the blade 10, when the blade is mounted on the hub, and a trailing edge 20 facing the opposite direction of the leading edge 18.

(15) The airfoil region 34 (also called the profiled region) has an ideal or almost ideal blade shape with respect to generating lift, whereas the root region 30 due to structural considerations has a substantially circular or elliptical cross-section, which for instance makes it easier and safer to mount the blade 10 to the hub. The diameter (or the chord) of the root region 30 may be constant along the entire root area 30. The transition region 32 has a transitional profile gradually changing from the circular or elliptical shape of the root region 30 to the airfoil profile of the airfoil region 34. The chord length of the transition region 32 typically increases with increasing distance r from the hub. The airfoil region 34 has an airfoil profile with a chord extending between the leading edge 18 and the trailing edge 20 of the blade 10. The width of the chord decreases with increasing distance r from the hub.

(16) A shoulder 40 of the blade 10 is defined as the position, where the blade 10 has its largest chord length. The shoulder 40 is typically provided at the boundary between the transition region 32 and the airfoil region 34. FIG. 2 also illustrates the longitudinal extent L, length or longitudinal axis of the blade.

(17) 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 providing 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.

(18) The blade is typically made from a pressure side shell part 36 and a suction side shell part 38 that are glued to each other along bond lines at the leading edge 18 and the trailing edge of the blade 20.

(19) FIG. 3 shows a schematic view of a cross section of the blade along the line I-I shown in FIG. 2. As previously mentioned, the blade 10 comprises a pressure side shell part 36 and a suction side shell part 38. The pressure side shell part 36 comprises a spar cap 41, also called a main laminate, which constitutes a load bearing part of the pressure side shell part 36. The spar cap 41 comprises a plurality of fibre layers 42 mainly comprising unidirectional fibres aligned along the longitudinal direction of the blade in order to provide stiffness to the blade. The suction side shell part 38 also comprises a spar cap 45 comprising a plurality of fibre layers 46. The pressure side shell part 38 may also comprise a sandwich core material 43 typically made of balsawood or foamed polymer and sandwiched between a number of fibre-reinforced skin layers. The sandwich core material 43 is used to provide stiffness to the shell in order to ensure that the shell substantially maintains its aerodynamic profile during rotation of the blade. Similarly, the suction side shell part 38 may also comprise a sandwich core material 47.

(20) The spar cap 41 of the pressure side shell part 36 and the spar cap 45 of the suction side shell part 38 are connected via a first shear web 50 and a second shear web 55. The shear webs 50, 55 are in the shown embodiment shaped as substantially I-shaped webs. The first shear web 50 comprises a shear web body and two web foot flanges. The shear web body comprises a sandwich core material 51, such as balsawood or foamed polymer, covered by a number of skin layers 52 made of a number of fibre layers.

(21) The blade shells 36, 38 may comprise further fibre-reinforcement at the leading edge and the trailing edge. Typically, the shell parts 36, 38 are bonded to each other via glue flanges.

(22) FIG. 4 is a schematic cut-open, exploded view of a wind turbine blade according to a co-pending application of the present applicant, wherein FIG. 5 is an enlarged view of the encircled section in FIG. 4. A pressure side shell half and a suction side shell half are typically manufactured over the entire length L of the wind turbine blade 10. A spar structure 62 is arranged within the shell. The spar structure 62 comprising a first part 64 and a second part 66, the first and second part being releasably coupled to each other, as shown in FIG. 8. The method advantageously comprises fixing the first part 64 of the spar structure 62 to one or both of the shell halves within the first blade segment 68 and fixing the second part 66 of the spar structure to one or both of the shell halves within the second blade segment 70.

(23) The shell halves are then closed and joined, such as glued together for obtaining a closed shell, which is subsequently cut along a cutting plane 69 substantially normal to the spanwise direction or longitudinal extent of the blade to obtain a first blade segment 68 and a second blade segment 70. The cutting plane 69 coincides with an end surface 65 of the first part 64 of the spar structure.

(24) As seen in FIGS. 4 and 5, the spar structure 62 extends across the cutting plane 69. As best seen in FIG. 5, the first part 64 of the spar structure 62, which takes the form of a box-shaped sheath member for at least partly enclosing the second part 66 of the spar structure in the illustrated embodiment, is fixed to the first blade segment 68. The second part 66 of the spar structure 62, which comprises a spar box in the illustrated embodiment, is fixed to the second blade segment 70, wherein the second part 66 extends beyond the second blade segment 70 into the first blade segment 68, when the blade segments are assembled.

(25) FIG. 5 also illustrates an access opening 80 within the upper half of the illustrated shell for accessing the spar structure and coupling and uncoupling the first and second part of the spar structure 62. For uncoupling, a locking pin, as illustrated in FIGS. 6-8, is withdrawn from the aligned respective apertures 76, 78 in each of the first and second part of the spar structure via the access opening 80. Prior to, or after, joining and sealing the first blade segment 68 to the second blade segment 70 for obtaining the wind turbine blade, the method advantageously comprises re-coupling the first and second part of the spar structure, via the access opening 80, as illustrated in FIG. 8, by re-inserting the locking pin 74 into the aligned respective apertures 76, 78 in each of the first and second part of the spar structure. As seen in FIGS. 4 and 5, the cutting step dl) does not comprise cutting the spar structure, only the shell halves are cut. In addition, two shear webs 82a, 82b are arranged within the first blade segment.

(26) FIGS. 6, 7 and 8 illustrate an embodiment of the spar structure 62 with the first part 64 in the form of a conductive, box-shaped sheath member according to a co-pending application of the present applicant. Preferably, the conductive sheath member is part of a lightning protection system of the wind turbine blade. The second part 66 of the spar structure comprises a box spar 67, part of which is encased in a jacket 72, for example comprising a conductive mesh 72. The spar structure 62 comprises a locking pin 74 for releasably coupling the first part 64 to the second part 66 of the spar structure through aligned respective locking apertures 76, 78 in each of the first and second part of the spar structure.

(27) FIG. 9 is a partial perspective view of an access opening 180 of a wind turbine blade. The wind turbine blade comprises a shell member 138, such as a suction side shell half, with an outer surface 110. The shell member 138 may comprise a first segment 168, such as a root end segment, connected to a second segment 170, such as a tip end segment. An access opening 180 is provided in the blade shell member 138 for allowing access to a hollow space within the blade, e.g. for inserting or withdrawing a locking pin 174 as described above.

(28) FIG. 10 is a partial perspective view of a wind turbine rotor blade 10 with a shell 83 having an outer surface 84, here illustrating the outer surface of a suction side shell half. In manufacturing the blade of the present invention, an access window 80 can be cut through the blade for allowing access to an interior space thereof, as indicated by the hatched line in FIG. 10. In the illustrated example of FIG. 10, the access window is substantially rectangular and is provided close to the trailing edge 20 of the blade.

(29) FIG. 11a is partial cross sectional view across the suction side shell half of a wind turbine blade according to the present invention, taken along the line A-A in FIG. 10, in which the access window 80 has been cut into the shell 83, giving access to an interior space of the blade 10. The aerodynamic shell 83 has an outer surface 84 forming at least part of an exterior surface of the wind turbine blade and an inner surface 85. The shell 83 comprises a recessed portion 86 at the inner surface 85 of the shell 83 adjacent to the access window 80. Here the recessed portion is provided in a stepped configuration, wherein the thickness of the shell 83 decreases in a discrete step towards the access window.

(30) As shown in FIG. 11b, a panel 87 arranged within the recessed portion 86 at the inner surface 85 of the shell 83 for closing the access window 80. During operation, the panel 87 is biased against the inner surface of the shell 83 by means of the pressure difference between the interior space of the blade and the outside, in particular the outside of the suction half of the shell. Such pressure difference will typically occur as pressure builds up inside the blade due to the centrifugal effect, whereas at the outside of the blade, the pressure is reduced due to the aerodynamic shape of the airfoil leading to high flow velocities above the suction side shell half. With the inwardly mounted panel of the present invention, the resulting pressure difference biases the panel against the recessed portion optionally via gasket 93, thus reducing the risk of pressure leakage and water ingress. As also illustrated, the panel 87 comprises a top surface 88 and a bottom surface 89, wherein at least part of the top surface 88 is flush with the outer surface 84 of the shell 83 surrounding the access window 80.

(31) FIG. 12 is a schematic top view of illustrating different shapes of the panel according to the present invention. The panel can, for example, be rectangular, rectangular with rounded corners, elliptical, or oval. Advantageously, the length Lp of the panel 87 exceeds the width Wp of the panel 87. This allows the panel 87 to be rotatable from a first position to a second position in a plane substantially parallel to the outer surface of the shell 83 surrounding the access window 80, such that the first position allows for insertion of the panel 87 into an interior space of the blade, wherein the second position allows for arranging the panel 87 within the recessed portion 86 at the inner surface of the shell 83 for closing the access window 80.

(32) FIG. 13 is a partial cross sectional view across a suction side shell half of a wind turbine rotor blade according to one embodiment of the present invention. Two hook members 95a, 95b extend from the bottom surface of the panel 87. Likewise, two hook members 94a, 94b extend from the inner surface 85 of the shell 83. Elastic straps 96a, 96b are fastened to the respective hook members 94a, 95a and 94b, 95b for fixing the panel 87 to the shell 83. The elastic straps can be fastened around the hook members during insertion and rotation of the panel.

(33) In the embodiment illustrated in FIG. 13, the panel 87 comprises a central portion 90 having a first thickness t1 and an outer tongue portion 91 having a second thickness t2, wherein the first thickness t1 exceeds the second thickness t2, and wherein at least part of the outer tongue portion 91 is arranged within the recessed portion 86 at the inner surface of the shell 83.

(34) 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.

LIST OF REFERENCE NUMERALS

(35) 4 tower 6 nacelle 8 hub 10 blades 14 blade tip 16 blade root 18 leading edge 20 trailing edge 30 root region 32 transition region 34 airfoil region 36 pressure side shell part 38, 138 suction side shell part 40 shoulder 41 spar cap 42 fibre layers 43 sandwich core material 45 spar cap 46 fibre layers 47 sandwich core material 50 first shear web 51 core member 52 skin layers 55 second shear web 56 sandwich core material of second shear web 57 skin layers of second shear web 60 filler ropes 62 spar structure 64 first part 65 end surface of first part 66 second part 67 spar member 68, 168 first blade segment 69 cutting plane 70, 170 second blade segment 72 jacket/mesh 74, 174 locking pin 76 aperture 78 aperture 80, 180 access window 82 shear web 83 shell 84 outer surface of shell 85 inner surface of shell 86 recessed portion 87 panel 88 top surface of panel 89 bottom surface of panel 90 central portion of panel 91 tongue portion of panel 93 gasket 94 hook member in shell 95 hook member in panel 96 elastic strap F force created by pressure difference L length Lp length of panel r distance from hub R rotor radius t1,2 first and second thickness Wp width of panel