CA2810759A1 - Flatback slat for wind turbine - Google Patents
Flatback slat for wind turbine Download PDFInfo
- Publication number
- CA2810759A1 CA2810759A1 CA2810759A CA2810759A CA2810759A1 CA 2810759 A1 CA2810759 A1 CA 2810759A1 CA 2810759 A CA2810759 A CA 2810759A CA 2810759 A CA2810759 A CA 2810759A CA 2810759 A1 CA2810759 A1 CA 2810759A1
- Authority
- CA
- Canada
- Prior art keywords
- slat
- wind turbine
- turbine blade
- trailing edge
- flatback
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
Links
- 230000007423 decrease Effects 0.000 claims description 5
- 238000000926 separation method Methods 0.000 description 4
- 230000006698 induction Effects 0.000 description 3
- 230000000694 effects Effects 0.000 description 2
- 239000000853 adhesive Substances 0.000 description 1
- 230000001070 adhesive effect Effects 0.000 description 1
- 230000001934 delay Effects 0.000 description 1
- RLQJEEJISHYWON-UHFFFAOYSA-N flonicamid Chemical compound FC(F)(F)C1=CC=NC=C1C(=O)NCC#N RLQJEEJISHYWON-UHFFFAOYSA-N 0.000 description 1
- 238000011084 recovery Methods 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
Classifications
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F03—MACHINES OR ENGINES FOR LIQUIDS; WIND, SPRING, OR WEIGHT MOTORS; PRODUCING MECHANICAL POWER OR A REACTIVE PROPULSIVE THRUST, NOT OTHERWISE PROVIDED FOR
- F03D—WIND MOTORS
- F03D1/00—Wind motors with rotation axis substantially parallel to the air flow entering the rotor
- F03D1/06—Rotors
- F03D1/0608—Rotors characterised by their aerodynamic shape
- F03D1/0633—Rotors characterised by their aerodynamic shape of the blades
- F03D1/0641—Rotors characterised by their aerodynamic shape of the blades of the section profile of the blades, i.e. aerofoil profile
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F03—MACHINES OR ENGINES FOR LIQUIDS; WIND, SPRING, OR WEIGHT MOTORS; PRODUCING MECHANICAL POWER OR A REACTIVE PROPULSIVE THRUST, NOT OTHERWISE PROVIDED FOR
- F03D—WIND MOTORS
- F03D1/00—Wind motors with rotation axis substantially parallel to the air flow entering the rotor
- F03D1/06—Rotors
- F03D1/0608—Rotors characterised by their aerodynamic shape
- F03D1/0633—Rotors characterised by their aerodynamic shape of the blades
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F03—MACHINES OR ENGINES FOR LIQUIDS; WIND, SPRING, OR WEIGHT MOTORS; PRODUCING MECHANICAL POWER OR A REACTIVE PROPULSIVE THRUST, NOT OTHERWISE PROVIDED FOR
- F03D—WIND MOTORS
- F03D1/00—Wind motors with rotation axis substantially parallel to the air flow entering the rotor
- F03D1/06—Rotors
- F03D1/065—Rotors characterised by their construction elements
- F03D1/0675—Rotors characterised by their construction elements of the blades
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F05—INDEXING SCHEMES RELATING TO ENGINES OR PUMPS IN VARIOUS SUBCLASSES OF CLASSES F01-F04
- F05B—INDEXING SCHEME RELATING TO WIND, SPRING, WEIGHT, INERTIA OR LIKE MOTORS, TO MACHINES OR ENGINES FOR LIQUIDS COVERED BY SUBCLASSES F03B, F03D AND F03G
- F05B2240/00—Components
- F05B2240/20—Rotors
- F05B2240/30—Characteristics of rotor blades, i.e. of any element transforming dynamic fluid energy to or from rotational energy and being attached to a rotor
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F05—INDEXING SCHEMES RELATING TO ENGINES OR PUMPS IN VARIOUS SUBCLASSES OF CLASSES F01-F04
- F05B—INDEXING SCHEME RELATING TO WIND, SPRING, WEIGHT, INERTIA OR LIKE MOTORS, TO MACHINES OR ENGINES FOR LIQUIDS COVERED BY SUBCLASSES F03B, F03D AND F03G
- F05B2240/00—Components
- F05B2240/20—Rotors
- F05B2240/30—Characteristics of rotor blades, i.e. of any element transforming dynamic fluid energy to or from rotational energy and being attached to a rotor
- F05B2240/305—Flaps, slats or spoilers
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E10/00—Energy generation through renewable energy sources
- Y02E10/70—Wind energy
- Y02E10/72—Wind turbines with rotation axis in wind direction
Abstract
An aerodynamic slat (30F) having a flatback trailing edge (44F) extending along and spaced proximate an inboard portion of a wind turbine blade (22). At least the leading edge (42F) of the slat may be disposed within a zone (48) of airflow that is generally parallel to the suction side (40) of the wind turbine blade over a range of air inflow angles. A splitter plate (52) may extend aft from the flatback trailing edge to reduce vortex shedding and extend the effective chord length of the slat.
Vortex generators (60) may be attached to the slat. Flatback slats may be retrofitted to a wind turbine rotor (20) by attaching them to the spar caps (56) of the blades or to the hub spinner (28). The flatback slat provides lift on low-lift inboard portions of the wind turbine blade over a range of angles of attack of the inboard portion.
Vortex generators (60) may be attached to the slat. Flatback slats may be retrofitted to a wind turbine rotor (20) by attaching them to the spar caps (56) of the blades or to the hub spinner (28). The flatback slat provides lift on low-lift inboard portions of the wind turbine blade over a range of angles of attack of the inboard portion.
Description
FLATBACK SLAT FOR WIND TURBINE
This application is a continuation-in-part of United States Application Number 13/438,040 filed on 03 April 2012 (attorney docket 2011P18073US) which is FIELD OF THE INVENTION
The invention relates generally to wind turbines and more particularly to an inboard slat for a wind turbine blade.
BACKGROUND OF THE INVENTION
The inboard portion of a wind turbine blade is made thick to support centrifugal and lift loads that are imposed onto the blade root by the outboard blade regions.
Herein "inboard" means radially inward toward the blade root, which is the portion of the separated flow region. Thus, the inboard region of the blades produces low lift and consequently low torque, and it therefore contributes little to the power of the wind turbine. Flow altering devices including slats and flaps have been added to wind turbine blades to improve their local and overall aerodynamic performance.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention is explained in the following description in view of the drawings that show:
FIG. 1 shows a downwind side of a wind turbine rotor according to an embodiment of the invention.
FIG. 2 is a perspective view of an inboard portion of a wind turbine blade according to an embodiment of the invention.
FIG. 3 shows a prior art wind turbine blade airfoil profile at a transverse section.
FIG. 4 shows a flatback slat airfoil profile at a transverse section of the slat.
FIG. 5 shows a profile of an inner portion of a wind turbine blade taken along line 5-5 of FIG 1.
FIG. 6 shows a prior art slat and blade profile.
FIG. 7 shows attachment of one embodiment of the present slat to a spar cap.
FIG. 8 shows a flatback slat producing vortex shedding.
FIG. 9 shows a splitter plate extending aft from mid-thickness of a flatback trailing edge.
FIG. 10 shows a splitter plate extending aft from a flatback trailing edge flush with the suction side of the slat.
FIG. 11 shows a splitter plate angled downward from a flatback trailing edge.
FIG. 12 shows one embodiment in which flatback slats are attached to the spinner of a wind turbine rotor.
FIG. 13 shows a back view of one embodiment of a flatback trailing edge in which a splitter plate migrates from a midpoint to an upper part of the trailing edge thickness.
FIG. 14 shows a back view of one embodiment of a flatback trailing edge with a thickness that tapers along a radial span of the slat.
This application is a continuation-in-part of United States Application Number 13/438,040 filed on 03 April 2012 (attorney docket 2011P18073US) which is FIELD OF THE INVENTION
The invention relates generally to wind turbines and more particularly to an inboard slat for a wind turbine blade.
BACKGROUND OF THE INVENTION
The inboard portion of a wind turbine blade is made thick to support centrifugal and lift loads that are imposed onto the blade root by the outboard blade regions.
Herein "inboard" means radially inward toward the blade root, which is the portion of the separated flow region. Thus, the inboard region of the blades produces low lift and consequently low torque, and it therefore contributes little to the power of the wind turbine. Flow altering devices including slats and flaps have been added to wind turbine blades to improve their local and overall aerodynamic performance.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention is explained in the following description in view of the drawings that show:
FIG. 1 shows a downwind side of a wind turbine rotor according to an embodiment of the invention.
FIG. 2 is a perspective view of an inboard portion of a wind turbine blade according to an embodiment of the invention.
FIG. 3 shows a prior art wind turbine blade airfoil profile at a transverse section.
FIG. 4 shows a flatback slat airfoil profile at a transverse section of the slat.
FIG. 5 shows a profile of an inner portion of a wind turbine blade taken along line 5-5 of FIG 1.
FIG. 6 shows a prior art slat and blade profile.
FIG. 7 shows attachment of one embodiment of the present slat to a spar cap.
FIG. 8 shows a flatback slat producing vortex shedding.
FIG. 9 shows a splitter plate extending aft from mid-thickness of a flatback trailing edge.
FIG. 10 shows a splitter plate extending aft from a flatback trailing edge flush with the suction side of the slat.
FIG. 11 shows a splitter plate angled downward from a flatback trailing edge.
FIG. 12 shows one embodiment in which flatback slats are attached to the spinner of a wind turbine rotor.
FIG. 13 shows a back view of one embodiment of a flatback trailing edge in which a splitter plate migrates from a midpoint to an upper part of the trailing edge thickness.
FIG. 14 shows a back view of one embodiment of a flatback trailing edge with a thickness that tapers along a radial span of the slat.
FIG. 15 shows a suction side view of one embodiment of a flatback slat with vortex generators along a forward suction side of the slat.
FIG. 16 shows a profile of a flatback slat with a vortex generator.
FIG. 17 shows exemplary contours of variation in flow angles about a turbine blade with an 8 variation in inflow angle of the relative wind.
FIG. 18 shows a mean camber line of a prior art multi-element airfoil.
FIG. 19 shows a mean camber line of a multi-element airfoil in an embodiment of the present invention.
DETAILED DESCRIPTION OF THE INVENTION
FIG 1 shows a downwind side of a wind turbine rotor 20 with radially-oriented blades 22, sometimes referred to as airfoils or main elements, which rotate generally in a plane 23 or disc of rotation. Only rotating elements are illustrated in this figure, with the typical nacelle and tower of a wind turbine not being shown. Each main blade 22 has a radially inboard end or root 24. The roots 24 are attached to a common hub 26 that may have a cover called a spinner 28. Each blade may have an aerodynamic flatback slat 30F as described herein mounted above an inboard portion of each blade 22 by mounting structures such as aerodynamic struts 32 or rods or stall fences.
FIG 2 is a perspective view of an inboard portion 36 of a blade 22 having a pressure side 38 and a suction side 40 between a leading edge 42 and a trailing edge 44. The transverse sectional profiles may vary from cylindrical Pc at the root 24 to an airfoil shape Pa at or past the shoulder 47, which is the position of longest chord on the blade 22. A flatback slat 30F is shown as later described.
FIG 3 illustrates a prior art wind turbine blade airfoil profile Pa with a pressure side 38 and a suction side 40. A straight chord line Ch spans between the leading edge 42 and the trailing edge 44. The length of the chord line Ch is the airfoil chord length.
A mean camber line Ca is the set of midpoints between the pressure and suction sides 38, 40. The mean camber line Ca coincides with the chord line Ch if the airfoil Pa is symmetric about the chord line Ch. A maximum thickness Tm relative to the chord length of the airfoil may be used to define a degree of thickness or thinness of the airfoil profile.
FIG. 16 shows a profile of a flatback slat with a vortex generator.
FIG. 17 shows exemplary contours of variation in flow angles about a turbine blade with an 8 variation in inflow angle of the relative wind.
FIG. 18 shows a mean camber line of a prior art multi-element airfoil.
FIG. 19 shows a mean camber line of a multi-element airfoil in an embodiment of the present invention.
DETAILED DESCRIPTION OF THE INVENTION
FIG 1 shows a downwind side of a wind turbine rotor 20 with radially-oriented blades 22, sometimes referred to as airfoils or main elements, which rotate generally in a plane 23 or disc of rotation. Only rotating elements are illustrated in this figure, with the typical nacelle and tower of a wind turbine not being shown. Each main blade 22 has a radially inboard end or root 24. The roots 24 are attached to a common hub 26 that may have a cover called a spinner 28. Each blade may have an aerodynamic flatback slat 30F as described herein mounted above an inboard portion of each blade 22 by mounting structures such as aerodynamic struts 32 or rods or stall fences.
FIG 2 is a perspective view of an inboard portion 36 of a blade 22 having a pressure side 38 and a suction side 40 between a leading edge 42 and a trailing edge 44. The transverse sectional profiles may vary from cylindrical Pc at the root 24 to an airfoil shape Pa at or past the shoulder 47, which is the position of longest chord on the blade 22. A flatback slat 30F is shown as later described.
FIG 3 illustrates a prior art wind turbine blade airfoil profile Pa with a pressure side 38 and a suction side 40. A straight chord line Ch spans between the leading edge 42 and the trailing edge 44. The length of the chord line Ch is the airfoil chord length.
A mean camber line Ca is the set of midpoints between the pressure and suction sides 38, 40. The mean camber line Ca coincides with the chord line Ch if the airfoil Pa is symmetric about the chord line Ch. A maximum thickness Tm relative to the chord length of the airfoil may be used to define a degree of thickness or thinness of the airfoil profile.
Vector Vw represents the wind velocity outside the influence of the rotor. An axial free-stream vector Va represents the axial component of the air inflow at the blade 22 after reduction of the wind velocity Vw by an axial induction factor a. In the known formula below, U1 is the wind speed outside the influence of the rotor and U2 is the wind speed at the rotor.
U1 ¨U2 UI
a = _________________________________________ Combining Va with a tangential velocity component Vt gives a relative inflow vector Vr at an angle (1) relative to the rotation plane 23. The angle of attack AoA is the angle between the relative inflow vector Vr and the chord line Ch. The twist angle 0 is the angle between the chord line Ch and the rotation plane 23. The lift vector L is perpendicular to the relative inflow vector Vr. A drag vector D is directed aft parallel to the inflow vector Vr.
A design target for a wind turbine airfoil may be an axial induction factor a of about 1/3, giving an axial free-stream vector Va Vw = 2/3. However, the axial induction factor a may be much less than 1/3 on the inner portion 36 of the blade due to aerodynamic stall or detachment, which can be attributed to the relatively high thickness Tm under the operating conditions, inefficient airfoil shapes, and the wide operating range of high angles of attack of the airfoil. A slat may be optimized for lift along this area of the main blade per aspects of the invention.
FIG 4 shows a profile of a flatback slat 30F, as may be used with embodiments of the present invention, with a chord line ChF from the leading edge 42F to a midpoint of a flatback trailing edge 44F, and a mean camber line CaF. A flatback slat herein is a slat with a flatback trailing edge 44F. This means the trailing edge comprises a flat or generally flat surface that is normal 40 or 30 to the mean camber line CaF or to the chord line ChF of the slat 30F in a transverse sectional profile. The flatback trailing edge 44F has a thickness Tf measured between the pressure side 38F and suction side 40F in the transverse profile of the slat. The thickness Tf may be at least 5%
of the chord length ChF of the slat 30F or 5 - 30% or 5 - 12.5% of the chord length of the slat in various embodiments. The thickness of the fiatback trailing edge 44F may decrease with increasing distance from the root 24 of the main blade element as shown in FIG 14.
FIG 5 shows an exemplary profile of the inner portion of the main blade 22, which receives inflow Vr at a greater angle of attack AoA than in FIG 3. A
stalled or 20 In one embodiment, the slat 30F may be disposed behind a line 50 drawn perpendicularly to the mean camber line Ca of the main blade element 22 at the leading edge 42 thereof. The slat may be spaced at a distance 43, measured at the minimum distance point in the illustrated cross-sectional view, from the suction side 40 of the inboard portion of the main blade element 22 throughout a radial span of the slat. The 40% or 15% - 40% of the selected or local chord Ch of the main blade element in various embodiments.
A slat chord line ChF may be defined per transverse section of the slat 30F
between the leading edge 42F and a midpoint of the flatback trailing edge 44F.
The divergence angle 51 between the chord line ChF of the slat 30F and the respective chord line Ch of the main element 22 may be for example 100 to 30 . Prior slats 30P as shown in FIG 6 are commonly located forward of the leading edge 42, and have a chord divergence angle 51 between ChP and Ch of 70 to 90 . They are positioned to delay stall on the main element, rather than for slat lift. They can produce some lift, but only at high angles of attack. The present slat 30F may be disposed in zone 48 throughout a radial span of the slat, or at least the leading edge 42F may be so disposed.
This locates the slat 30F where it can provide lift over a broader range of operating conditions. This position also allows the slat to be attached to the spar cap 56 of the main blade element 22, as shown in FIG 7, where it is easier to attach solidly than in the prior slat position of FIG 6, making a retrofit attachment kit practical. Such a kit may include the slat 30F, a support structure such as rods 58 or struts 32 (FIG 2) for connecting the slat to an existing wind turbine rotor, and optionally, fastening devices such as screws, blind bolts, and/or adhesive. The chord divergence angle 51 may decrease over the span of the slat with distance from the root 24 of the main blade element 22, because the twist as a function of radial span is different between the main element 22 and the slat 30F; i.e. a twist rate in the slat may exceed a corresponding twist rate of the main element 22 along the radial span of the slat.
FIG 8 shows a flatback slat 30F producing von Karman vortex shedding as may occur under some conditions. To avoid this, FIG 9 shows a splitter plate 52 extending aft from the flatback trailing edge 44F. The splitter plate 52 prevents vortex shedding when it would otherwise occur by holding two stationary vortices 54 against the trailing edge 44F. This extends the effective chord length ChF of the slat, and promotes off-surface pressure recovery for the flow over the suction side of the slat.
Shedding vortices create oscillating/fluctuating pressure fields across the flat trailing edge 44F
and thus create a large amount of pressure drag. By adding a splitter plate 52, and creating standing vortices 54, the fluctuating flow is replaced with a quasi-steady one, and drag is reduced. An additional benefit is that the aerodynamic influence of the slat is extended further downstream, which further speeds the flow between the slat and the main element, and delays the onset of flow separation on the main element 22.
The splitter plate 52 may extend aft from the flatback trailing edge 44F by a distance effective to prevent Karman vortex shedding from the flatback trailing edge, for example by a distance of at least 5% of the chord length of the slat. In one embodiment, the splitter plate 52 may extend aft from the flatback trailing edge 44F from a midpoint in the thickness Tf of the flatback trailing edge. In one embodiment, the splitter plate 52 may be oriented normally 20 to the flatback trailing edge 44F. In FIG 10 the splitter plate 52 extends aft from the flatback trailing edge flush with a suction side 40F
of the slat 30F, thus forming an aft extension of the suction side of the slat, increasing lift on the slat. In FIG lithe splitter plate 52 is angled downward or toward the main blade element, such as up to 30 relative to the camber line CaF at the flatback slat trailing edge Tf. This increases the nozzle effect between the slat and the main blade element 22. The splitter plate 52 may have a thickness of less than 20% of the thickness Tf of the flatback trailing edge 44F, and it may be a flat plate. The splitter plate 52 may leave space for at least one stationary vortex proximate the flatback trailing edge 44F; i.e. it does not form a flush extension of both the pressure and suction sides 38F, 40F. The splitter plate 52 may migrate from a midpoint on the thickness Tf of the flatback trailing edge 44F at an inboard end 30A of the slat 30F to an upper part of the flatback trailing edge at an outboard end 30E3 of the slat, as later shown in FIG. 13.
FIG 12 shows one embodiment of the invention in which flatback slats 30F are attached to the hub 26 of the wind turbine rotor 20, so as to extend along, and be spaced proximate, the inboard portion of the blade 22. This embodiment may be provided in a retrofit kit for attaching the slats 30F to an existing wind turbine rotor. For example, the support structure of the kit may contain rings, plates, or brackets that can be bolted to the hub or spinner. Alternately, the support structure may include a replacement spinner fabricated with slat mounts.
FIG 13 shows a back view of one embodiment of a flatback trailing edge 44F
with a splitter plate 52 that migrates from a midpoint on the thickness If of the flatback =
trailing edge 44F at an inboard end 30A of the slat to an upper part of the flatback trailing edge 44F at an outboard end 30B of the slat.
FIG 14 shows a back view of one embodiment of a flatback trailing edge 44F in which the thickness Tf of the flatback trailing edge decreases with increasing distance from a root of the main blade element. Inboard end 30A of the slat is closer to the root 24 of the main blade element than is the outboard end 30B of the slat.
FIG 15 shows a suction side view of one embodiment of a flatback slat 30F with a suction side 40F, a leading edge 42F, a trailing edge 44F, and a plurality of vortex generators 60 along the forward suction side 40F of the slat 30F. FIG 16 shows a profile of a flatback slat 30F with a pressure side 38F, a suction side 40F, a leading edge 42F, a trailing edge 44F, a chord line ChF, a mean camber line CaF, and a vortex generator. The height Hv of the vortex generators 60 may be for example at least 80%
of a boundary layer thickness on the slat. The vortex generators 60 reduce flow separation on the aft suction side of the flatback slat. They may also reduce vortex shedding behind the flatback trailing edge 44F. They may be used synergistically with the splitter plates 52 previously described, or they may be used without splitter plates.
In addition to their effects on the slat, they may also reduce flow separation on the suction side 40 of the main blade element 22. The retrofit options previously described for installing the slats provide a way to reduce flow separation on the main blade 22 via vortex generators 60 on the slats 30F.
FIG 17 shows exemplary contours of variation in flow angles about a turbine blade with an 8 variation in inflow angle of the relative wind Vr. From such contours a zone 48 of parallel flow or reduced variation in inflow angle as previously described may be selected for positioning a slat 30F therein.
FIG 18 shows a prior art slat 30P located forward of the main airfoil element 22, thus extending the effective length of the combined multi-element airfoil 22C.
The mean camber line CaC of the multi-element airfoil 22C is extended forward, but is not changed in curvature. Consequently, the prior slat 30P does not increase lift at all angles of attack. As shown in FIG 19, the present slat 30F being located in zone 48 (shown in FIG 5), increases the curvature of the effective mean camber line CaC of the multi-element airfoil 22C, and therefore increases the lift it produces at all angles of attack.
While various embodiments of the present invention have been shown and described herein, it will be obvious that such embodiments are provided by way of example only. Numerous variations, changes and substitutions may be made without departing from the invention herein. Accordingly, it is intended that the invention be limited only by the spirit and scope of the appended claims.
U1 ¨U2 UI
a = _________________________________________ Combining Va with a tangential velocity component Vt gives a relative inflow vector Vr at an angle (1) relative to the rotation plane 23. The angle of attack AoA is the angle between the relative inflow vector Vr and the chord line Ch. The twist angle 0 is the angle between the chord line Ch and the rotation plane 23. The lift vector L is perpendicular to the relative inflow vector Vr. A drag vector D is directed aft parallel to the inflow vector Vr.
A design target for a wind turbine airfoil may be an axial induction factor a of about 1/3, giving an axial free-stream vector Va Vw = 2/3. However, the axial induction factor a may be much less than 1/3 on the inner portion 36 of the blade due to aerodynamic stall or detachment, which can be attributed to the relatively high thickness Tm under the operating conditions, inefficient airfoil shapes, and the wide operating range of high angles of attack of the airfoil. A slat may be optimized for lift along this area of the main blade per aspects of the invention.
FIG 4 shows a profile of a flatback slat 30F, as may be used with embodiments of the present invention, with a chord line ChF from the leading edge 42F to a midpoint of a flatback trailing edge 44F, and a mean camber line CaF. A flatback slat herein is a slat with a flatback trailing edge 44F. This means the trailing edge comprises a flat or generally flat surface that is normal 40 or 30 to the mean camber line CaF or to the chord line ChF of the slat 30F in a transverse sectional profile. The flatback trailing edge 44F has a thickness Tf measured between the pressure side 38F and suction side 40F in the transverse profile of the slat. The thickness Tf may be at least 5%
of the chord length ChF of the slat 30F or 5 - 30% or 5 - 12.5% of the chord length of the slat in various embodiments. The thickness of the fiatback trailing edge 44F may decrease with increasing distance from the root 24 of the main blade element as shown in FIG 14.
FIG 5 shows an exemplary profile of the inner portion of the main blade 22, which receives inflow Vr at a greater angle of attack AoA than in FIG 3. A
stalled or 20 In one embodiment, the slat 30F may be disposed behind a line 50 drawn perpendicularly to the mean camber line Ca of the main blade element 22 at the leading edge 42 thereof. The slat may be spaced at a distance 43, measured at the minimum distance point in the illustrated cross-sectional view, from the suction side 40 of the inboard portion of the main blade element 22 throughout a radial span of the slat. The 40% or 15% - 40% of the selected or local chord Ch of the main blade element in various embodiments.
A slat chord line ChF may be defined per transverse section of the slat 30F
between the leading edge 42F and a midpoint of the flatback trailing edge 44F.
The divergence angle 51 between the chord line ChF of the slat 30F and the respective chord line Ch of the main element 22 may be for example 100 to 30 . Prior slats 30P as shown in FIG 6 are commonly located forward of the leading edge 42, and have a chord divergence angle 51 between ChP and Ch of 70 to 90 . They are positioned to delay stall on the main element, rather than for slat lift. They can produce some lift, but only at high angles of attack. The present slat 30F may be disposed in zone 48 throughout a radial span of the slat, or at least the leading edge 42F may be so disposed.
This locates the slat 30F where it can provide lift over a broader range of operating conditions. This position also allows the slat to be attached to the spar cap 56 of the main blade element 22, as shown in FIG 7, where it is easier to attach solidly than in the prior slat position of FIG 6, making a retrofit attachment kit practical. Such a kit may include the slat 30F, a support structure such as rods 58 or struts 32 (FIG 2) for connecting the slat to an existing wind turbine rotor, and optionally, fastening devices such as screws, blind bolts, and/or adhesive. The chord divergence angle 51 may decrease over the span of the slat with distance from the root 24 of the main blade element 22, because the twist as a function of radial span is different between the main element 22 and the slat 30F; i.e. a twist rate in the slat may exceed a corresponding twist rate of the main element 22 along the radial span of the slat.
FIG 8 shows a flatback slat 30F producing von Karman vortex shedding as may occur under some conditions. To avoid this, FIG 9 shows a splitter plate 52 extending aft from the flatback trailing edge 44F. The splitter plate 52 prevents vortex shedding when it would otherwise occur by holding two stationary vortices 54 against the trailing edge 44F. This extends the effective chord length ChF of the slat, and promotes off-surface pressure recovery for the flow over the suction side of the slat.
Shedding vortices create oscillating/fluctuating pressure fields across the flat trailing edge 44F
and thus create a large amount of pressure drag. By adding a splitter plate 52, and creating standing vortices 54, the fluctuating flow is replaced with a quasi-steady one, and drag is reduced. An additional benefit is that the aerodynamic influence of the slat is extended further downstream, which further speeds the flow between the slat and the main element, and delays the onset of flow separation on the main element 22.
The splitter plate 52 may extend aft from the flatback trailing edge 44F by a distance effective to prevent Karman vortex shedding from the flatback trailing edge, for example by a distance of at least 5% of the chord length of the slat. In one embodiment, the splitter plate 52 may extend aft from the flatback trailing edge 44F from a midpoint in the thickness Tf of the flatback trailing edge. In one embodiment, the splitter plate 52 may be oriented normally 20 to the flatback trailing edge 44F. In FIG 10 the splitter plate 52 extends aft from the flatback trailing edge flush with a suction side 40F
of the slat 30F, thus forming an aft extension of the suction side of the slat, increasing lift on the slat. In FIG lithe splitter plate 52 is angled downward or toward the main blade element, such as up to 30 relative to the camber line CaF at the flatback slat trailing edge Tf. This increases the nozzle effect between the slat and the main blade element 22. The splitter plate 52 may have a thickness of less than 20% of the thickness Tf of the flatback trailing edge 44F, and it may be a flat plate. The splitter plate 52 may leave space for at least one stationary vortex proximate the flatback trailing edge 44F; i.e. it does not form a flush extension of both the pressure and suction sides 38F, 40F. The splitter plate 52 may migrate from a midpoint on the thickness Tf of the flatback trailing edge 44F at an inboard end 30A of the slat 30F to an upper part of the flatback trailing edge at an outboard end 30E3 of the slat, as later shown in FIG. 13.
FIG 12 shows one embodiment of the invention in which flatback slats 30F are attached to the hub 26 of the wind turbine rotor 20, so as to extend along, and be spaced proximate, the inboard portion of the blade 22. This embodiment may be provided in a retrofit kit for attaching the slats 30F to an existing wind turbine rotor. For example, the support structure of the kit may contain rings, plates, or brackets that can be bolted to the hub or spinner. Alternately, the support structure may include a replacement spinner fabricated with slat mounts.
FIG 13 shows a back view of one embodiment of a flatback trailing edge 44F
with a splitter plate 52 that migrates from a midpoint on the thickness If of the flatback =
trailing edge 44F at an inboard end 30A of the slat to an upper part of the flatback trailing edge 44F at an outboard end 30B of the slat.
FIG 14 shows a back view of one embodiment of a flatback trailing edge 44F in which the thickness Tf of the flatback trailing edge decreases with increasing distance from a root of the main blade element. Inboard end 30A of the slat is closer to the root 24 of the main blade element than is the outboard end 30B of the slat.
FIG 15 shows a suction side view of one embodiment of a flatback slat 30F with a suction side 40F, a leading edge 42F, a trailing edge 44F, and a plurality of vortex generators 60 along the forward suction side 40F of the slat 30F. FIG 16 shows a profile of a flatback slat 30F with a pressure side 38F, a suction side 40F, a leading edge 42F, a trailing edge 44F, a chord line ChF, a mean camber line CaF, and a vortex generator. The height Hv of the vortex generators 60 may be for example at least 80%
of a boundary layer thickness on the slat. The vortex generators 60 reduce flow separation on the aft suction side of the flatback slat. They may also reduce vortex shedding behind the flatback trailing edge 44F. They may be used synergistically with the splitter plates 52 previously described, or they may be used without splitter plates.
In addition to their effects on the slat, they may also reduce flow separation on the suction side 40 of the main blade element 22. The retrofit options previously described for installing the slats provide a way to reduce flow separation on the main blade 22 via vortex generators 60 on the slats 30F.
FIG 17 shows exemplary contours of variation in flow angles about a turbine blade with an 8 variation in inflow angle of the relative wind Vr. From such contours a zone 48 of parallel flow or reduced variation in inflow angle as previously described may be selected for positioning a slat 30F therein.
FIG 18 shows a prior art slat 30P located forward of the main airfoil element 22, thus extending the effective length of the combined multi-element airfoil 22C.
The mean camber line CaC of the multi-element airfoil 22C is extended forward, but is not changed in curvature. Consequently, the prior slat 30P does not increase lift at all angles of attack. As shown in FIG 19, the present slat 30F being located in zone 48 (shown in FIG 5), increases the curvature of the effective mean camber line CaC of the multi-element airfoil 22C, and therefore increases the lift it produces at all angles of attack.
While various embodiments of the present invention have been shown and described herein, it will be obvious that such embodiments are provided by way of example only. Numerous variations, changes and substitutions may be made without departing from the invention herein. Accordingly, it is intended that the invention be limited only by the spirit and scope of the appended claims.
Claims (20)
1. A wind turbine blade comprising:
a main blade element comprising a radially inboard portion; and a flatback slat comprising a flatback trailing edge spaced proximate the main blade element along a radial span of the inboard portion.
a main blade element comprising a radially inboard portion; and a flatback slat comprising a flatback trailing edge spaced proximate the main blade element along a radial span of the inboard portion.
2. The wind turbine blade of claim 1, wherein the flatback trailing edge comprises a generally flat surface that is normal~ 30° to a mean camber line of the slat or to a chord line of the slat, and has a thickness of 5% to 30% of a chord length of the slat.
3. The wind turbine blade of claim 1, wherein the thickness of the flatback trailing edge decreases along a radial extent of the slat with increasing distance from a root of the main blade element.
4. The wind turbine blade of claim 1, wherein a line is defined perpendicular to a mean camber line of the main blade element at a leading edge of the main blade element, and the slat is disposed behind said line and spaced from a suction side of the inboard portion of the main blade element throughout a radial span of the slat.
5. The wind turbine blade of claim 1, wherein at least a portion of a leading edge of the slat is disposed within a zone of parallel flow wherein an operational airflow flows parallel ~ 6° to a suction side of the main blade element throughout a variation of at least 8° in an inflow angle to the primary blade element.
6. The wind turbine blade of claim 5, wherein the slat is disposed within the zone of parallel flow throughout a radial span of the slat.
7. The wind turbine blade of claim 1, wherein at least a leading edge of the slat is disposed within a zone of reduced inflow angle variation, wherein, when an angle of an operational air inflow to the main blade element changes by N degrees relative to a chord line of the main blade element, an angle of a resultant air inflow to the slat changes by only up to N / 2 degrees relative to a chord line of the slat throughout a variation of at least 8° in an inflow angle to the primary blade element.
8. The wind turbine blade of claim 7, wherein the slat is spaced from a suction side of the main blade element by distance of 5% to 10% of a selected chord length of the main blade element along a radial span of the slat, and the slat is disposed within the zone of reduced inflow angle variation throughout the radial span of the slat.
9. The wind turbine blade of claim 1, further wherein the slat is attached to a spinner of a hub of the main blade element.
10. The wind turbine blade of claim 1, wherein, for each transverse section through the slat and main blade element, a chord line of the slat forms an angle with a respective chord line of the main blade element of 10 to 30 degrees.
11. The wind turbine blade of claim 10, wherein said angle decreases with increasing distance from a root of the main blade element via a twist in the slat that exceeds a corresponding twist in the main blade element along a radial span of the slat.
12. The wind turbine blade of claim 1, further comprising a splitter plate extending aft from the flatback trailing edge effective to prevent vortex shedding from the flatback trailing edge.
13. The wind turbine blade of claim 12, wherein the splitter plate extends aft from the flatback trailing edge from a midpoint in the thickness of the flatback trailing edge by a distance of at least 5% of the chord length of the slat.
14. The wind turbine blade of claim 12, wherein the splitter plate is oriented normally ~ 20° to the flatback trailing edge.
15. The wind turbine blade of claim 12, wherein the splitter plate is angled toward the main blade element at an angle of up to 30 degrees relative to a chord line of the flatback slat.
16. The wind turbine blade of claim 12, wherein the splitter plate extends aft from the flatback trailing edge flush with a suction side of the slat, and forms an aft extension of the suction side of the slat.
17. The wind turbine blade of claim 12, wherein the splitter plate migrates from a midpoint on the thickness of the flatback trailing edge at an inboard end of the slat to an upper part of the flatback trailing edge at an outboard end of the slat.
18. The wind turbine blade of claim 1, further comprising a plurality of vortex generators along a forward suction side of the slat.
19. The wind turbine blade of claim 1, further comprising a support structure attaching the slat to a suction side spar cap of the main blade element.
20. A kit comprising:
a slat comprising a flatback trailing edge; and a support structure and associated fastening mechanism for attaching the slat along and spaced proximate an inboard portion of a wind turbine blade.
a slat comprising a flatback trailing edge; and a support structure and associated fastening mechanism for attaching the slat along and spaced proximate an inboard portion of a wind turbine blade.
Applications Claiming Priority (4)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US13/438,040 US9175666B2 (en) | 2012-04-03 | 2012-04-03 | Slat with tip vortex modification appendage for wind turbine |
US13/438,040 | 2012-04-03 | ||
US13/477,469 US9151270B2 (en) | 2012-04-03 | 2012-05-22 | Flatback slat for wind turbine |
US13/477,469 | 2012-05-22 |
Publications (1)
Publication Number | Publication Date |
---|---|
CA2810759A1 true CA2810759A1 (en) | 2013-10-03 |
Family
ID=47757409
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
CA2810759A Abandoned CA2810759A1 (en) | 2012-04-03 | 2013-03-28 | Flatback slat for wind turbine |
Country Status (7)
Country | Link |
---|---|
US (1) | US9151270B2 (en) |
EP (1) | EP2647837A3 (en) |
JP (1) | JP2013213500A (en) |
KR (1) | KR20130112770A (en) |
CN (1) | CN103362755B (en) |
BR (1) | BR102013007919A2 (en) |
CA (1) | CA2810759A1 (en) |
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
CN105971817A (en) * | 2016-06-03 | 2016-09-28 | 北京唐浩电力工程技术研究有限公司 | Fairing front winglet of wind turbine generator and wind turbine generator with winglet |
CN110072773A (en) * | 2016-12-12 | 2019-07-30 | 庞巴迪公司 | Aircraft slat |
Families Citing this family (19)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP2383465A1 (en) * | 2010-04-27 | 2011-11-02 | Lm Glasfiber A/S | Wind turbine blade provided with a slat assembly |
EP2548800A1 (en) | 2011-07-22 | 2013-01-23 | LM Wind Power A/S | Method for retrofitting vortex generators on a wind turbine blade |
US20150211487A1 (en) * | 2014-01-27 | 2015-07-30 | Siemens Aktiengesellschaft | Dual purpose slat-spoiler for wind turbine blade |
KR101498684B1 (en) * | 2013-12-31 | 2015-03-06 | 한국에너지기술연구원 | Flat Back Airfoil having Diagonal type Trailing Edge Shape and Blade for Wind Turbine Generator having the Same |
US11143160B2 (en) * | 2014-07-14 | 2021-10-12 | Lm Wp Patent Holding A/S | Aeroshell extender piece for a wind turbine blade |
US9658124B2 (en) | 2014-11-05 | 2017-05-23 | General Electric Company | System and method for wind turbine operation |
US10094358B2 (en) * | 2015-07-21 | 2018-10-09 | Winnova Energy LLC | Wind turbine blade with double airfoil profile |
WO2017039666A1 (en) | 2015-09-03 | 2017-03-09 | Siemens Aktiengesellschaft | Wind turbine blade with trailing edge tab |
CN106870277A (en) * | 2015-12-10 | 2017-06-20 | 李亦博 | Efficiently using the blade and its manufacture method of low velocity fluid |
CN106438455B (en) * | 2016-11-18 | 2019-03-15 | 江苏省水利勘测设计研究院有限公司 | A kind of low cavitation coefficient, cavitation factor, Toma coefficient axial--flow blading pump with aileron |
DE102018103678A1 (en) * | 2018-02-19 | 2019-08-22 | Wobben Properties Gmbh | Rotor blade of a wind turbine with a splitter plate |
EP3587798B1 (en) * | 2018-06-27 | 2020-10-14 | Siemens Gamesa Renewable Energy A/S | Aerodynamic structure |
EP3587799A1 (en) | 2018-06-27 | 2020-01-01 | Siemens Gamesa Renewable Energy A/S | Aerodynamic structure |
DE102018127367A1 (en) * | 2018-11-02 | 2020-05-07 | Wobben Properties Gmbh | Rotor blade for a wind turbine and wind turbine |
CN111502907B (en) * | 2019-01-30 | 2022-03-01 | 上海电气风电集团股份有限公司 | Vortex generator, fan blade and wind driven generator comprising same |
CN110107450A (en) * | 2019-04-29 | 2019-08-09 | 上海理工大学 | A kind of composite vane type pneumatic equipment bladess |
CN112746929B (en) * | 2019-10-31 | 2022-07-26 | 江苏金风科技有限公司 | Blade stall monitoring method, device, equipment and storage medium |
CN110683033B (en) * | 2019-10-31 | 2023-03-21 | 哈尔滨工程大学 | But roll adjustment formula rotor |
CN113090442B (en) * | 2019-12-23 | 2022-09-06 | 江苏金风科技有限公司 | Adjustable wing blade, control method and control device thereof and wind generating set |
Family Cites Families (34)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US2135887A (en) * | 1935-06-07 | 1938-11-08 | Fairey Charles Richard | Blade for airscrews and the like |
DK174261B1 (en) * | 2000-09-29 | 2002-10-21 | Bonus Energy As | Device for use in regulating air flow around a wind turbine blade |
US6769872B2 (en) * | 2002-05-17 | 2004-08-03 | Sikorsky Aircraft Corporation | Active control of multi-element rotor blade airfoils |
US6666648B2 (en) * | 2002-05-17 | 2003-12-23 | Sikorsky Aircraft Corporation | Directional elastomeric coupler |
DE10347802B3 (en) | 2003-10-10 | 2005-05-19 | Repower Systems Ag | Rotor blade for a wind turbine |
US7637721B2 (en) * | 2005-07-29 | 2009-12-29 | General Electric Company | Methods and apparatus for producing wind energy with reduced wind turbine noise |
BRPI0600613B1 (en) | 2006-03-14 | 2015-08-11 | Tecsis Tecnologia E Sist S Avançados S A | Multi-element blade with aerodynamic profiles |
CN101454564B (en) | 2006-04-02 | 2014-04-23 | 考特能源有限公司 | Wind turbine with slender blade |
ES2294927B1 (en) * | 2006-05-31 | 2009-02-16 | Gamesa Eolica, S.A. | AIRLINER SHOVEL WITH DIVERGING OUTPUT EDGE. |
ES2310958B1 (en) * | 2006-09-15 | 2009-11-10 | GAMESA INNOVATION & TECHNOLOGY, S.L. | OPTIMIZED AEROGENERATOR SHOVEL. |
US20080166241A1 (en) | 2007-01-04 | 2008-07-10 | Stefan Herr | Wind turbine blade brush |
US7883324B2 (en) * | 2007-01-09 | 2011-02-08 | General Electric Company | Wind turbine airfoil family |
US7828523B2 (en) | 2007-03-27 | 2010-11-09 | General Electric Company | Rotor blade for a wind turbine having a variable dimension |
ES2326352B1 (en) * | 2007-09-14 | 2010-07-15 | GAMESA INNOVATION & TECHNOLOGY, S.L. | AEROGENERATOR SHOVEL WITH DEFLECTABLE ALERONS CONTROLLED BY CHANGES OF PRESSURE ON THE SURFACE. |
EP2078852B2 (en) | 2008-01-11 | 2022-06-22 | Siemens Gamesa Renewable Energy A/S | Wind turbine rotor blade |
DE202008006801U1 (en) | 2008-05-20 | 2009-03-19 | Plathner, Carl | Flow receptor with symmetrical main profile and slat |
DE102008026474A1 (en) * | 2008-06-03 | 2009-12-10 | Mickeler, Siegfried, Prof. Dr.-Ing. | Rotor blade for a wind turbine and wind turbine |
NL1035525C1 (en) | 2008-06-03 | 2009-07-06 | Hugo Karel Krop | Adjustable rotor blade for e.g. wind turbine, includes extendible profile part such as flap or slat |
EP2253835A1 (en) | 2009-05-18 | 2010-11-24 | Lm Glasfiber A/S | Wind turbine blade with base part having non-positive camber |
EP2253838A1 (en) | 2009-05-18 | 2010-11-24 | Lm Glasfiber A/S | A method of operating a wind turbine |
EP2253836A1 (en) | 2009-05-18 | 2010-11-24 | Lm Glasfiber A/S | Wind turbine blade |
EP2253839A1 (en) | 2009-05-18 | 2010-11-24 | Lm Glasfiber A/S | Wind turbine blade provided with flow altering devices |
EP2253834A1 (en) | 2009-05-18 | 2010-11-24 | Lm Glasfiber A/S | Wind turbine blade with base part having inherent non-ideal twist |
EP2253837A1 (en) | 2009-05-18 | 2010-11-24 | Lm Glasfiber A/S | Method of manufacturing a wind turbine blade having predesigned segment |
DK2432993T3 (en) | 2009-05-19 | 2013-11-11 | Vestas Wind Sys As | A WINDMILL AND PROCEDURE |
US8684690B2 (en) * | 2009-05-26 | 2014-04-01 | Agustawestland North America, Inc | Variable chord morphing helicopter rotor |
US8011886B2 (en) * | 2009-06-30 | 2011-09-06 | General Electric Company | Method and apparatus for increasing lift on wind turbine blade |
US8303250B2 (en) * | 2009-12-30 | 2012-11-06 | General Electric Company | Method and apparatus for increasing lift on wind turbine blade |
EP2383465A1 (en) * | 2010-04-27 | 2011-11-02 | Lm Glasfiber A/S | Wind turbine blade provided with a slat assembly |
US20110142676A1 (en) * | 2010-11-16 | 2011-06-16 | General Electric Company | Rotor blade assembly having an auxiliary blade |
US8240995B2 (en) * | 2010-12-20 | 2012-08-14 | General Electric Company | Wind turbine, aerodynamic assembly for use in a wind turbine, and method for assembling thereof |
US20110223022A1 (en) * | 2011-01-28 | 2011-09-15 | General Electric Company | Actuatable surface features for wind turbine rotor blades |
US8777580B2 (en) * | 2011-11-02 | 2014-07-15 | Siemens Aktiengesellschaft | Secondary airfoil mounted on stall fence on wind turbine blade |
US8376703B2 (en) * | 2011-11-21 | 2013-02-19 | General Electric Company | Blade extension for rotor blade in wind turbine |
-
2012
- 2012-05-22 US US13/477,469 patent/US9151270B2/en active Active
-
2013
- 2013-02-25 EP EP13156527.7A patent/EP2647837A3/en active Pending
- 2013-03-28 CA CA2810759A patent/CA2810759A1/en not_active Abandoned
- 2013-04-02 BR BRBR102013007919-7A patent/BR102013007919A2/en not_active IP Right Cessation
- 2013-04-02 KR KR1020130035728A patent/KR20130112770A/en not_active Application Discontinuation
- 2013-04-02 JP JP2013076820A patent/JP2013213500A/en not_active Ceased
- 2013-04-03 CN CN201310114531.9A patent/CN103362755B/en active Active
Cited By (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
CN105971817A (en) * | 2016-06-03 | 2016-09-28 | 北京唐浩电力工程技术研究有限公司 | Fairing front winglet of wind turbine generator and wind turbine generator with winglet |
CN110072773A (en) * | 2016-12-12 | 2019-07-30 | 庞巴迪公司 | Aircraft slat |
CN110072773B (en) * | 2016-12-12 | 2022-10-21 | 庞巴迪公司 | Aircraft slat |
Also Published As
Publication number | Publication date |
---|---|
EP2647837A2 (en) | 2013-10-09 |
EP2647837A3 (en) | 2017-08-16 |
KR20130112770A (en) | 2013-10-14 |
US9151270B2 (en) | 2015-10-06 |
US20130259702A1 (en) | 2013-10-03 |
JP2013213500A (en) | 2013-10-17 |
CN103362755A (en) | 2013-10-23 |
CN103362755B (en) | 2017-09-29 |
BR102013007919A2 (en) | 2015-06-16 |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
US9151270B2 (en) | Flatback slat for wind turbine | |
US9175666B2 (en) | Slat with tip vortex modification appendage for wind turbine | |
EP2589797B1 (en) | Wind turbine blade comprising a slat mounted on a stall fence of the wind turbine blade | |
CN102046965B (en) | A wind turbine blade with an auxiliary airfoil | |
AU2013213758B2 (en) | Wind turbine rotor blade | |
EP2275672B1 (en) | Boundary layer fins for wind turbine blade | |
US10974818B2 (en) | Vortex generator arrangement for an airfoil | |
US9523279B2 (en) | Rotor blade fence for a wind turbine | |
WO2013060722A1 (en) | Wind turbine blade provided with slat | |
EP3037656B1 (en) | Rotor blade with vortex generators | |
WO2007045244A1 (en) | Blade for a wind turbine rotor | |
WO2013014082A2 (en) | Wind turbine blade comprising vortex generators | |
EP2592265A3 (en) | Power producing spinner for a wind turbine | |
WO2014006542A2 (en) | Turbine arrangement | |
US20150322916A1 (en) | Soiling shield for wind turbine blade | |
RU2499155C2 (en) | Vane blade |
Legal Events
Date | Code | Title | Description |
---|---|---|---|
FZDE | Discontinued |
Effective date: 20190328 |