Source: https://patents.google.com/patent/US8469672/en
Timestamp: 2018-04-24 01:14:58
Document Index: 409355432

Matched Legal Cases: ['§371', 'art 12', 'art 12', 'art 15', 'art 16', 'arts 15', 'arts 15', 'arts 15']

US8469672B2 - Blade for a wind turbine rotor - Google Patents
Blade for a wind turbine rotor Download PDF
US8469672B2
US8469672B2 US13446715 US201213446715A US8469672B2 US 8469672 B2 US8469672 B2 US 8469672B2 US 13446715 US13446715 US 13446715 US 201213446715 A US201213446715 A US 201213446715A US 8469672 B2 US8469672 B2 US 8469672B2
US13446715
US20120257982A1 (en )
F05B2260/97—Reducing windage losses
Provided is a blade for a rotor of a wind turbine having a substantially horizontal rotor shaft, said rotor comprising a hub, from which the blade extends substantially radially when mounted, said blade having a chord plane extending between a leading edge and a trailing edge of said blade, a root area closest to the hub, an airfoil area furthest away from the hub, a transition area between the root area and the airfoil area, a first airfoil extending substantially along the entire airfoil area, and a second airfoil separately mounted to the blade, said second airfoil arranged at a mutual distance transverse to the chord plane and extending along the root area of the blades.
This is a Continuation Application of U.S. patent application Ser. No. 12/083,638, filed Apr. 16, 2008, which was filed under 35 U.S.C. §371 as a national stage of PCT/DK2006/000582, filed Oct. 17, 2006, which claims priority to Danish application PA 2005 01451, filed on Oct. 17, 2005, the contents of each of which are hereby incorporated by reference in their entirety.
This principle is also know in connection with blades for wind turbines, i.a. by manufacturing wind turbines with two or more rotors. CA 2 395 612 describes a wind turbine with two co-axial rotors where one rotor rotates faster than the second. GB 758 628 describes a wind turbine with two co-axial rotors rotating in opposite directions.
U.S. Pat. No. 5,161,952 discloses a biplane construction for wind turbine rotors. The wind turbine is designed so that two straight blades are connected with the hub of the rotor at a distance from each other. The tips of the two blades are interconnected.
According to a preferred embodiment of the invention, the chord plane of at least the one root segment with airfoil profile is substantially parallel to the chord plane of the blade itself in the area closest to the hub. Preferably, the chord plane of the blade is twisted in the longitudinal direction of the blade in order to compensate for the increase in local velocity of the blade with increasing distance from the hub, which means that the blade “sees” the wind direction differently depending on the radius from the hub. This means that in this embodiment, the course of the chord plane in the longitudinal direction of the root area is a continuation of the course of the chord plane in the longitudinal direction of the airfoil area and/or the transition area.
According to a particular embodiment, the transition area comprises at least a first transition segment and a second transition segment, said segments being arranged with a mutual distance, as seen transverse to the chord plane, where at least one of the transition segments is provided with an airfoil profile. Preferably, the chord plane of the at least one transition segment with airfoil profile is substantially parallel to the chord plane of the blade itself at the transition between the transition area and the air-foil area, and preferably, both transition segments are provided with airfoil profiles.
Typically, the total length of the root area and the transition area is between 5% and 35% of the total length of the blade, and often between 5% and 25% of the total length of the blade or even between 5% and 15% of the total length of the blade.
FIG. 3B shows the mounting area of the blade. The profiles of the blade segments in this area are formed such that they lie within a corresponding conventional blade with circular root part (shown with the dashed line 12). The first root segment 7 is provided with an airfoil profile in the mounting area comprising a chord plane K1, while the second root segment 8 is provided with a profile reducing the wind resistance of the segment, without necessarily contributing to the production of the wind turbine. The first, root segment 7 merges into the first transition segment 9 also provided with an airfoil profile comprising a chord plane K3. The second root segment 8 merges into the second transition segment 10 and changes gradually from a profile with reduced wind resistance at the mounting area to an actual airfoil profile comprising a chord plane K4 at the second transition segment 10. The chord plane K of the blade is usually twisted along the longitudinal direction of the blade to compensate for the local velocity of the blade. Therefore, the course of the chord planes K1, K3, and K4 are a continuation of the course of the chord plane K of the blade in the airfoil area 4.
FIGS. 4 and 5 show a second and third embodiment of the invention, respectively, and which are modifications of the embodiment shown in FIG. 3. Therefore, only the differences are discussed here. In the second embodiment shown in FIG. 4 the second root segment 8 1 is also provided with an airfoil profile comprising a chord plane K2 at the mounting area. Furthermore, the profile of the root segment 8 1 extends beyond the conventional circular profile of the root part 12, as is apparent in FIG. 4B. The figure also shows that the chord planes of the two segments may be mutually angled.
According to the third embodiment shown in FIG. 5, the first and the second root segments 7 2, 8 2 as well as the first and the second transition segments 9 2, 10 2 have symmetric profiles. The profiles are shown with the chord planes parallel to the direction of rotation of the blade, however, the profiles may preferably be angled with respect to the direction of rotation, where the angle is selected based on maximising the lift.
As seen from FIG. 5B, both the first root segment 7 2 and the second root segment 8 2 extend beyond the circular profile of the conventional root part 12. Finally, it should be noted that the root segments of the embodiment shown in FIGS. 4 and 5 as well as the embodiment shown in FIG. 3 each merge into a corresponding transition segment (9 2, 9 3, 10 2, 10 3), said segments joining to form a common profile at the transition between the transition area 3 and the airfoil area 4.
FIG. 6 shows a fourth embodiment of the blade, where the first root segment 7 3 and the second root segment 8 3 are joined at the mounting area 22. As seen in FIG. 6B, the mounting area 22 is circular and contains mounting holes 11, the blades being secured to the hub by bolts through said holes. The blade is thus adapted to conventional hubs and can thus replace existing blades on already installed wind turbines during a renewal.
FIG. 7 shows a fifth embodiment of the blade, where the first root segment 7 4 and the second root segment 8 4 are joined at the mounting area 22, but where the two segments are not joint at a distance to the hub, but instead appear as two separate blade parts with different lengths. It is also apparent from FIG. 7 that the various root segments do not necessarily have the same thickness.
FIG. 8 shows a sixth embodiment of the blade, where a first, a second and a third root segment 7 5, 8 5, 13 merge into a first, a second and a third transition segment 9 5, 10 5, 14, respectively. The first and the second root segments 7 5, 8 5 as well as the first and the second transition segments 9 5, 10 5 are here shown with a shape reducing the wind resistance of these segments, while the third root segment 13 and the third transition segment 14 are provided with an actual airfoil profile. However, the profiles may all be provided with profiles increasing the lift of the corresponding areas and thereby also the production of the wind turbine. Of course, the three root segments 7 5, 8 5, 13 may be joined at the mounting area just like the embodiment shown in FIGS. 6 and 7.
FIG. 9 shows an embodiment corresponding to the embodiment of FIG. 6, but where the blade is additionally provided with a first separately mounted blade part 15 and a second separately mounted blade part 16. The separately mounted blade parts 15, 16 are mounted on the first and the second root segment 7 3, 8 3, respectively, by means of a number of retaining means 18. The blade parts 15 and 16 extend along the root area 2 and optionally also along the transition area 3 of the blade. The blade itself does not necessarily have to have two root segments and/or transition segments, but may have a form where there is no gap 17, no root segments and/or transition segments, in which case the root area and the transition area of the blade correspond to a conventional blade. This embodiment is advantageous in that the separately mounted blade parts 15, 16 may be mounted without having to exchange the blades on already installed wind turbines. The retaining means may be formed with e.g. a drag reduction profile for lowering wind resistance and noise immissions.
The invention has been described with reference to preferred embodiments. Many modifications are conceivable without thereby deviating from the scope of the invention. Modifications and variations apparent to those skilled in the art are considered to fall within the scope of the present invention. For example, the embodiment shown in FIG. 9 may have only a single separately mounted blade part. Embodiments are also conceivable where the various segments have a separate blade angle regulation.
1. A blade for a rotor of a wind turbine having a substantially horizontal rotor shaft, said rotor comprising a hub, from which the blade extends substantially radially when mounted, said blade comprising:
a chord plane extending between a leading edge and a trailing edge of said blade;
a root area closest to the hub;
an airfoil area furthest away from the hub;
a transition area between the root area and the airfoil area;
a first airfoil extending substantially along the entire airfoil area; and
a second airfoil separately mounted to the blade, said second airfoil arranged at a mutual distance transverse to the chord plane and extending along the root area of the blade.
2. The blade according to claim 1, wherein the second airfoil further extends along the transition region of the blade.
3. The blade according to claim 1, wherein the root area has a substantially circular cross-section and the transition area has a shape gradually changing from the substantially circular shape of the root area to a profile of the first airfoil.
4. The blade according to claim 1, wherein
the blade comprises at least a first root segment and a second root segment along substantially the entire root area,
the segments are at a mutual distance transverse to the chord plane, and
at least one of the first root segment and the second root segment has an airfoil profile.
5. The blade according to claim 4, wherein the chord plane of the at least one root segment with airfoil profile is substantially parallel to the chord plane of the blade itself in the root area closest to the hub.
6. The blade according to claim 4, wherein the first and the second root segments have first and second airfoil profiles.
7. The blade according to claim 4, wherein
the chord plane of the at least one root segment having an airfoil profile has a substantially constant width,
the chord plane of the transition area widens with increasing distance from the hub, and
the chord plane of the first airfoil narrows with increasing distance from the hub.
8. The blade according to claim 4 wherein the first and the second root segments join at a portion of the transition area closest to the hub.
9. The blade according to claim 4 wherein
the first and the second root segments merge into the first and the second transition segments, and
the first and the second transition segments join with a portion of the transition area furthest away from the hub.
10. The blade according to claim 4 wherein
the first and the second transition segments join with the portion of the transition area furthest away from the hub.
11. The blade according to claim 10, wherein the portion of the root area where the first and second root segments join has a substantially circular cross section.
12. The blade according to claim 4 wherein
the first and the second root segments join and form a common mounting area at a portion of the root area.
13. The blade according to claim 1, wherein the chord plane of the blade twists up to 80 degrees in a longitudinal direction of the blade.
14. The blade according to claim 1, wherein
the transition area further comprises a first transition segment and a second transition segment,
the segments arranged at a mutual distance as seen transverse to the chord plane, and
at least one of the first and second transition segments has an airfoil profile.
15. The blade according to claim 14, wherein the chord plane of the at least one transition segment having an airfoil profile is substantially parallel to the chord plane of the blade at a transition between the blade transition area and the first airfoil area.
16. The blade according to claim 15, wherein
17. The blade according to claim 14, wherein
18. A blade for a rotor of a wind turbine having a substantially horizontal rotor shaft, said rotor comprising a hub, from which the blade extends substantially radially when mounted, said blade comprising:
a chord plane extending between the leading edge and the trailing edge of said blade;
an airfoil substantially along the entire airfoil area; and
a first root segment and a second root segment along substantially the entire root area, said segments arranged at a mutual distance transverse to the chord plane, wherein at least one of the first and second root segments has an airfoil profile and is a separately mounted segment.
US13446715 2005-10-17 2012-04-13 Blade for a wind turbine rotor Active US8469672B2 (en)
DK200501451 2005-10-17
DKPA200501451 2005-10-17
DK176317B1 DK176317B1 (en) 2005-10-17 2005-10-17 Blade for a rotor of a wind power installation
PCT/DK2006/000582 WO2007045244A1 (en) 2005-10-17 2006-10-17 Blade for a wind turbine rotor
US8363808 true 2008-04-16 2008-04-16
US13446715 US8469672B2 (en) 2005-10-17 2012-04-13 Blade for a wind turbine rotor
US13899099 US8864473B2 (en) 2005-10-17 2013-05-21 Blade for a wind turbine rotor
US12083638 Continuation
PCT/DK2006/000582 Continuation WO2007045244A1 (en) 2005-10-17 2006-10-17 Blade for a wind turbine rotor
US8363808 Continuation 2008-04-16 2008-04-16
US13899099 Continuation US8864473B2 (en) 2005-10-17 2013-05-21 Blade for a wind turbine rotor
US20120257982A1 true US20120257982A1 (en) 2012-10-11
US8469672B2 true US8469672B2 (en) 2013-06-25
ID=37560977
US12083638 Active 2029-09-15 US8177517B2 (en) 2005-10-17 2006-10-17 Blade for a wind turbine rotor
US13446715 Active US8469672B2 (en) 2005-10-17 2012-04-13 Blade for a wind turbine rotor
US13899099 Active US8864473B2 (en) 2005-10-17 2013-05-21 Blade for a wind turbine rotor
US (3) US8177517B2 (en)
EP (3) EP2163760B1 (en)
CN (3) CN101300419B (en)
CA (1) CA2625997C (en)
DE (1) DE602006011640D1 (en)
DK (1) DK176317B1 (en)
ES (2) ES2340522T3 (en)
WO (1) WO2007045244A1 (en)
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