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WO2013045601A1 - Pale d'éolienne - Google Patents

Pale d'éolienne Download PDF

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Publication number
WO2013045601A1
WO2013045601A1 PCT/EP2012/069169 EP2012069169W WO2013045601A1 WO 2013045601 A1 WO2013045601 A1 WO 2013045601A1 EP 2012069169 W EP2012069169 W EP 2012069169W WO 2013045601 A1 WO2013045601 A1 WO 2013045601A1
Authority
WO
WIPO (PCT)
Prior art keywords
array
blade
trailing edge
wind turbine
projecting
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.)
Ceased
Application number
PCT/EP2012/069169
Other languages
English (en)
Inventor
Carlos ARCE
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
LM Wind Power AS
Original Assignee
LM Wind Power AS
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by LM Wind Power AS filed Critical LM Wind Power AS
Publication of WO2013045601A1 publication Critical patent/WO2013045601A1/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

Links

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
    • F03D7/00—Controlling wind motors 
    • F03D7/02—Controlling wind motors  the wind motors having rotation axis substantially parallel to the air flow entering the rotor
    • F03D7/022—Adjusting aerodynamic properties 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
    • F03D7/00—Controlling wind motors 
    • F03D7/02—Controlling wind motors  the wind motors having rotation axis substantially parallel to the air flow entering the rotor
    • F03D7/0296—Controlling wind motors  the wind motors having rotation axis substantially parallel to the air flow entering the rotor to prevent, counteract or reduce noise emissions
    • 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
    • F05B2240/31—Characteristics of rotor blades, i.e. of any element transforming dynamic fluid energy to or from rotational energy and being attached to a rotor of changeable form or shape
    • 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
    • F05B2240/31—Characteristics of rotor blades, i.e. of any element transforming dynamic fluid energy to or from rotational energy and being attached to a rotor of changeable form or shape
    • F05B2240/311—Characteristics of rotor blades, i.e. of any element transforming dynamic fluid energy to or from rotational energy and being attached to a rotor of changeable form or shape flexible or elastic
    • 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
    • F05B2260/00—Function
    • F05B2260/96—Preventing, counteracting or reducing vibration or noise
    • 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

Definitions

  • the present invention relates to a wind turbine blade having adjustable noise reduction features.
  • a large portion of the noise produced during wind turbine operation is due to turbu- lence formed at the trailing edge of a wind turbine blade, as the low pressure, relatively faster suction-side airflow meets with the high pressure, relatively slower pressure-side airflow.
  • trailing edge additions may be incorporated into the blade trailing edge at the design stage, or may be retrofitted at a later date.
  • extensive testing and modelling may be required in order to select the optimal serrated profile or bristle configuration for the particular blade design used. Any variation in design requirements, oper- ating conditions, etc., may result in redesign of blade components and/or complicated retrofitting operations. It is an object of the invention to provide a wind turbine blade having noise reducing features which can be adjusted without requiring complicated redesign and/or retrofitting operations.
  • a wind turbine blade for a rotor of a wind turbine having a substantially horizontal rotor shaft, the rotor comprising a hub, from which the wind turbine blade extends substantially in a radial direction when mounted to the hub, the wind turbine blade extending in a longitudinal direction parallel to a longitudinal axis and having a tip end and a root end,
  • the wind turbine blade further comprising a profiled contour including a pressure side and a suction side, as well as a leading edge and a trailing edge with a chord having a chord length extending therebetween, the profiled contour, when being impacted by an incident airflow, generating a lift,
  • wind turbine blade further comprises at least a first array of projecting flow modulation elements provided at the trailing edge of the contour, said flow modulation elements projecting in a direction substantially away from the leading edge of the contour,
  • At least one characteristic of said flow modulating profile is adjustable to provide variable modulation of noise spectra at the trailing edge, wherein said at least one characteristic is selected from the following: the geometrical shape of said flow modulating profile; the translational location of said at least a first array relative to said trailing edge.
  • the the flexibility of at least one projecting flow modulation element of said at least a first array may additionally or alternatively be adjustable.
  • the trailing edge of the blade is configured to have a flow modulating profile, to disrupt the turbulent airflow at the trailing edge of the blade, and accordingly to act as a damper or noise reducer during operation of a wind turbine having such a blade.
  • This flow modulating profile is formed by at least one array of projecting flow modulation elements, which extend from the trailing edge of the blade.
  • the noise modulation can be tuned to more effectively reduce the noise produced by the wind turbine at any period of operation, without performing an on-site manual adjustment or retrofitting of a different noise modulating profile.
  • a system may be actively controlled (e.g. using suitable actuators to adjust location, surface dimensions, etc.), or may be passively regulated (e.g. the profile is configured to adjust shape, position, etc. as wind speed and/or centrifugal force increases).
  • said array extends in a longitudinal direction along at least a portion of the length of the wind turbine blade between said root end and said tip end.
  • the array is provided substantially at the trailing edge of the blade, along a portion of the length of the blade.
  • the array is at least provided towards the distal end of the blade, towards the blade tip end.
  • the array is at least substantially provided in the region of approximately 60-100% of the length of the blade from the root end of the blade, preferably 60-95%.
  • the array is spaced from the tip end of the blade by between 2-10 centimetres along the longitudinal direction of the blade, preferably approximately 5 centimetres from the tip end of the blade.
  • the flow modulating profile formed at least in part by the array, acts to modulate a boundary layer flow at the trailing edge of the blade.
  • said projecting flow modulation elements have a length approximately equal to 5-25% of the chord length of the blade at the location of said projecting flow modulation elements, preferably between 15-25%, advantageously around 20%.
  • the effective length of the projections will also decrease to match the reduction in boundary layer separation at that particular point along the blade. This ensures an efficient and effective operation of the projecting flow modulation elements to reduce the noise along the length of the blade.
  • a wind turbine blade for a rotor of a wind turbine hav- ing a substantially horizontal rotor shaft, the rotor comprising a hub, from which the wind turbine blade extends substantially in a radial direction when mounted to the hub, the wind turbine blade extending in a longitudinal direction parallel to a longitudinal axis and having a tip end and a root end,
  • the wind turbine blade further comprising a profiled contour including a pres- sure side and a suction side, as well as a leading edge and a trailing edge with a chord having a chord length extending therebetween, the profiled contour, when being impacted by an incident airflow, generating a lift,
  • wind turbine blade further comprises at least a first array of projecting flow modulation elements provided at the trailing edge of the contour, said flow modulation elements projecting in a direction substantially away from the leading edge of the contour,
  • said at least a first array of projecting flow modulation elements is translationally moveable relative to said trailing edge, such that said flow modulating profile is adjustable to provide variable modulation of noise spectra at the trailing edge.
  • Providing a translationally moveable array of flow modulation elements allows for the effective modulation of noise at the trailing edge of the blade to be adjusted by the relative motion of the array with respect to the trailing edge.
  • said at least a first array is moveable in a longitudinal direction substantially parallel to the longitudinal axis of the blade. Additionally or alternatively, said at least a first array is moveable in a chordal direction parallel to the chord of the wind turbine blade (i.e. in a direction transverse to the longitudinal axis). The array may be moved in a combination of longitudinal and chordal directions. Additionally or alternatively, the at least a first array is moveable along an axis between the pressure side and the suction side of the blade, along an axis perpendicular to the longitudinal direction of the blade, extending between the pressure side and the suction side, i.e. along a flapwise direction of the blade.
  • the array to be moved in a direction transverse to the longitudinal axis of the blade and to the chordal axis of the blade, i.e. in an up/down direction relative to the airfoil profile of the blade.
  • the at least a first array is moveable between a first position substantially on the pressure side of the wind turbine blade contour and a second position substantially on the suction side of the wind turbine blade contour.
  • the array allows for the array to be adjusted to primarily modulate either a boundary layer flow of the pressure side or a boundary layer flow of the suction side of the blade, or a combination or the two.
  • the blade is operable to move the at least a first array between predefined set point positions. Additionally or alternatively, the blade is operable to con- tinually vary the position of the at least one array.
  • the blade is operable to move the at least one array in a vibrational motion.
  • the at least one array may be operable to vibrate back and forth between a first and second position, to provide a modulation of the airflow at the trailing edge of the blade.
  • the rate of vibration and/or the vibrational distance of the array may be regulated to provide a controlled modulation of the airflow.
  • the blade may comprise any suitable arrangement of vibration and/or damping devices, to operation of which may be regulated, either passively or actively or a combination or active and passive regulation, to control the modulation effect at the trailing edge of the wind turbine blade.
  • said at least a first array comprises a plurality of individual array members having a subset of projecting flow modulation elements, the array members positioned along the longitudinal length of the wind turbine blade, wherein each of said individual array members is independently moveable relative to said trailing edge.
  • the flow modulating profile may be made up of a plurality of separate arrays provided at the trailing edge and located along the length of the blade, each array being independently moveable. Accordingly, adjustment of the flow modulating profile at the trailing edge may vary along the length of the wind turbine blade, to account for variations in the airflow encountered along the length of the blade.
  • said array of projecting flow modulation elements comprises a plate having a plurality of serrations projecting from said plate.
  • the use of a serrated edge at the trailing edge acts to modulate the noise generated by turbulent airflow at the trailing edge of the wind turbine blade.
  • said array of projecting flow modulation elements comprises a plate having a series of bristles projecting from said plate.
  • bristles at the trailing edge acts to modulate the turbulent airflow.
  • said series of bristles project from substantially the entire longitudinal length of said plate.
  • Providing bristles on the at least a first array can allow for the effective length of the presented bristles at the trailing edge to be varied, as the location of the array is moved with respect to the trailing edge, e.g. by moving the array back from the trailing edge in the direction of the leading edge of the blade, the bristles may be effectively retracted into the body of the blade profile, presenting a shorter free length of bristles.
  • said array comprises a plurality of clusters of bristles projecting from said plate, said clusters of bristles spaced along the longitudinal length of said panel.
  • the bristles can be provided in the form of clusters of plurality of bristles, said clusters having an approximate diameter of 2-3cms, wherein the distance between the notional centre of adjacent bristle clusters is approximately 5cms.
  • the wind turbine blade further comprises at least a second array of projecting flow modulation elements provided at said trailing edge, said first and second arrays extending adjacently in a longitudinal direction along at least a portion of the length of the wind turbine blade between said root end and said tip end, wherein said flow modulating profile is formed by the combination of said first and second arrays of projecting flow modulation elements, wherein at least said first array is moveable relative to said second array to adjust the geometry of the presented flow modulating profile.
  • the first and second arrays are arranged in parallel.
  • said at least a first array is translationally moveable relative to said second array.
  • the first array may have longer serration length than the second array, and the effective modulating profile presented at the trailing edge may be adjusted by the relative movement of the first array relative to the second array - as the first array is advanced from the trailing edge beyond the second array, the longer serrations of the first array act as the dominant modulating elements; when the first array is retracted, the shorter serrations of the second array may provide a different modulation effect.
  • the projecting flow modulation elements of said first and second arrays at least partially overlap.
  • said first and second arrays of projecting flow modulation elements comprise first and second serrated plates having a plurality of serrations extending from each plate to form a serrated edge.
  • said serrations comprise substantially triangular serrations having a proximal base end and a distal tip end. It will be understood however that the presented serrations may be any suitable shape to perform effective flow modulation at the trailing edge of the blade, e.g. square serrations, semi-circular, etc.
  • the projecting flow modulation elements are defined by appropriate dimensions, wherein the dimensions of the projecting flow modulation elements of the first array are substantially equal to the dimensions of the projecting flow modulation elements of the second array. Alternatively, the dimensions of the projecting flow modulation elements of the first array are different to the dimensions of the projecting flow modulation elements of the second array.
  • Such dimensions may include the length of the elements, thickness of elements, spacing between adjacent elements, etc.
  • such dimensions may include for example the angle of the serra- tions.
  • the projecting flow modulation elements comprising bristles such dimensions may include the thickness of the bristles, flexibility of bristles, etc.
  • the projecting flow modulation elements comprising spaced bristle clusters such dimensions may include the spacing distance between adjacent clusters, the number of bristles per cluster, etc.
  • a first serrated plate may have longer serrations, different angle of serration, different spacing, etc.
  • the first serrated plate may comprise serrations having a length approximately equal to twice the length of the serrations of the second plate. Additionally or alternatively, the first serrated plate may have a serration angle of approximately 75 degrees, while the second serrated plate may have a serration angle of approximately 60 degrees.
  • said first array comprises a first base plate having a first plurality of spaced flow modulation elements projecting therefrom
  • said second array comprises a second base plate having a second plurality of spaced flow modulation elements projecting therefrom, the first and second arrays having a gap defined between adjacent flow modulation elements
  • said first array is moveable in a direction parallel to the longitudinal axis of the blade, from a first position wherein the first plurality of flow modulation elements of said first array are substantially coincident with the second plurality of flow modulation elements of said second array,
  • the profile presented at the trailing edge can be adjusted based on the overlap between the first and second arrays.
  • said first and second plurality of flow modulation elements comprise serrations, said first and second arrays comprising serrated plates.
  • said first and second plurality of flow modulation elements comprise a plurality of bristle clusters projecting from said first and second base plates.
  • the relative movement between the arrays allows for the profile of bristles at the trailing edge to be varied - e.g. having spaces defined between the bristle clusters when the two arrays are in line, or substantially continuously bristled when the first array is offset relative to the second array. This allows for the varied modulation of the airflow at the trailing edge.
  • At least said first array is moveable in a direction substantially parallel to the chordal direction of the blade, from a first substantially retracted position wherein said first plurality of flow modulation elements of said first array are substantially retracted relative to said second plurality of flow modulation elements of said second array,
  • the elements (e.g. serrations or bristles) of the first array can be retreated or extended relative to the elements of the second array. This allow for the elements of the first array to provide proportionally more (if advanced) or less (if retracted) modulation than the elements of the second array.
  • the elements of the first array are configured differently to the elements of the second array, to ensure a different resulting modulation effect.
  • serrated plates this may occur in differences in serration length, serration spacing, serration angle, etc.
  • bristled plates this may occur in differences in cluster size, thicknesses of bristles, bristle length, bristle flexibility, bristle density per length of plate, etc.
  • said first and second arrays of projecting flow modulation ele- ments comprise a serrated array and a bristled array.
  • the dominant form of trailing edge noise modulation can be performed by serrations, bristles, or some combination of the two.
  • the type of modulation performed by the flow modulation trailing edge can be adjusted as required.
  • the bristles are more flexible and can easily adapt to a changing flow direction at the trailing edge of the blade.
  • the serrations of the serrated plate may be designed for optimal noise-reducing performance during nominal operation conditions for the particular wind turbine, while the bristles may be effectively deployed for operating conditions outside of nominal levels, to provide for more efficient noise-reducing performance of the blade for all possible operating conditions.
  • said first array of projecting flow modulation elements comprises a first serrated plate
  • said second array of projecting flow modulation elements comprises a plate having a series of bristles projecting from said plate.
  • the movement of the at least a first array may be operated using an active control system. Additionally or alternatively, said movement may be operated us- ing a passive control system.
  • the at least a first array is coupled to a translational actuator operable to translationally move said at least a first array relative to said trailing edge. Additionally or alternatively, said at least a first array is coupled to a biasing mechanism to bias said first array to a first at-rest position, wherein said at least a first array is operable to move from said first at-rest position to a second actuated position under a centrifugal force experienced by the wind turbine blade during rotation of the wind turbine blade.
  • the use of a biasing system that allows for the movement of the array during normal operation of the wind turbine blade due to centrifugal force experienced by the blade provides for a simple passive control of the adjustment of the flow modulating profile.
  • the second actuated position may be any suitable translational position of the array relative to the initial at rest position.
  • the at rest position corresponds to the first substantially retracted position of the first array and the actuated position corresponds to the second substantially advance position of the first array.
  • the biasing mechanism may include but is not limited to one or more of the following: a spring element, a hydraulic biasing element, frictional elements, pulleys, cams, etc.
  • At least one rail is provided in said blade, said at least a first array moveable on said rail from a first position to a second position, wherein when in said first position the projecting flow modulation elements of said at least a first array are retracted relative to the trailing edge of said blade, and when in said second position the projecting flow modulation elements of said at least a first array project beyond the trailing edge of said blade.
  • a wind turbine blade for a rotor of a wind turbine having a substantially horizontal rotor shaft, the rotor comprising a hub, from which the wind turbine blade extends substantially in a radial direction when mounted to the hub, the wind turbine blade extending in a longitudinal direction parallel to a longitudinal axis and having a tip end and a root end,
  • the wind turbine blade further comprising a profiled contour including a pressure side and a suction side, as well as a leading edge and a trailing edge with a chord having a chord length extending therebetween, the profiled contour, when being impacted by an incident airflow, generating a lift,
  • wind turbine blade further comprises at least a first array of pro- jecting flow modulation elements provided at the trailing edge of the contour, said flow modulation elements projecting substantially in a direction away from the leading edge of the contour,
  • the geometrical shape of said flow modulating profile is adjustable to provide variable modulation of noise spectra at the trailing edge.
  • the modulation effect provided at the trailing edge can be regulated or controlled according to the operating conditions of the wind turbine blade. This provides a considerable advantage over known systems, wherein the shape of the modulating profile can only be changed through a relatively complicated service operation to install a new trailing edge profile.
  • the characteristics of the actual flow modulation elements may be adjusted to provide variable noise modulation at the blade trailing edge.
  • the characteristics may include features such as the flexibility or malleability of the elements of the flow modulating profile.
  • said at least a first array further comprises at least one actuatable member provided on said array, said actuatable member operable to adjust the geometry of said flow modulating profile to provide variable modulation of noise spectra at the trailing edge, wherein the actuatable member is adjustable between a first state and a second state.
  • the member may be switchable between said first and second states, or may be operable to provide a tunable member which allows for a variable adjustment of said member between a first state and a second state.
  • the blade may have predefined modulation set points which it can effectively switch between, which may be specifically designed to modulate particular acoustic frequencies, or the blade may be able to effectively tune the modulation required through a substantially continuously variable, or substantially analogue, adjustment of the flow modulating profile.
  • said at least one actuatable member is inflatable.
  • a member may be inflatable using a suitable fluid, e.g. hydraulic fluid, water, pressurised gas, ambient air, etc.
  • the blade may comprise an internal reservoir of such a fluid and a pumping device operable to selectively inflate said at least one actuatable member by pumping a quantity of said fluid between said reservoir and said actuatable member.
  • the blade may comprise at least one inlet defined on the blade body, the inlet communicatively coupled to the at least one actuatable member to channel ambient air into said actuatable member to inflate said member during rotation of the wind turbine blade.
  • said actuatable member is a piezoelectric element.
  • piezoelectric actuation allows for an accurate control of the state of the element, which may be easily incorporated into a suitable control system for efficient regulation of operation.
  • said at least a first array of projecting flow modulation elements comprises a plate having a plurality of serrations projecting from said plate, preferably said serrations comprise substantially triangular serrations having a proximal base end and a distal tip end.
  • said at least one actuatable member is operable to adjust the length of the serrations provided on said plate.
  • the actuatable member may be provided at the outer tip end of the serrations, and effectively extends the tip end of the serrations when actuated.
  • the actuatable member may also be provided over the entire serration body, and operable to increase the overall serration dimensions and geometry when actuated. Additionally or alternatively, said at least one actuatable member is operable to adjust the distance between the distal tip ends of adjacent serrations.
  • said at least a first array comprises at least one actuatable member provided between adjacent serrations on said plate.
  • the actuatable member is preferably operable to provide an additional inter-serration projection when actuated.
  • the actuatable member may be shaped to provide a projection having a profile similar to the profile of said serrations when actuated.
  • the actuatable member may be shaped to provide a projection having a profile different to the profile of said serrations when actuated.
  • the actuatable member may provide a hemispherical profile when actuated on an array, where the original serrations are triangular or pyramidal in shape.
  • the wind turbine blade comprises a flexible membrane provided at the trailing edge of the blade, wherein the blade is operable to adaptively shape said flexible membrane to present an adaptive flow modulating profile at the trailing edge of the wind turbine blade.
  • the wind turbine blade comprises a plurality of arm members coupled to said membrane, wherein said arm members are operable to be moved relative to said trailing edge to adjust the shape of said flexible membrane provided at said trailing edge.
  • the arm members may be advanced from or retracted into the blade body, acting to vary or stretch the profile of the flexible membrane surface. As the arms project further from the trailing edge, the flexible membrane stretches to form a substan- tially serrated surface.
  • said plurality of arm members are coupled to an actuation bar to provide for actuation of said arm members.
  • said plurality of arm members comprise a bar end pivotably coupled to an actuation bar and a membrane end connected to said flexible membrane, wherein a movement of said actuation bar along the longitudinal axis of the wind turbine blade results in a movement of the membrane end of said arm members relative to the trailing edge of the wind turbine blade, to adjust the surface of the membrane pro- vided at said trailing edge.
  • said at least one array of projecting flow modulation elements comprises a plate having a series of bristles projecting from said plate. The bristles may project from substantially the entire longitudinal length of said plate.
  • said array comprises a plurality of clusters of bristles projecting from said plate, said clusters of bristles spaced along the longitudinal length of said panel.
  • the blade is operable to adjust the length of the bristles projecting from said plate.
  • the bristles may be provided as the free ends of coils located within the blade body, wherein a first end of the coil extends out from the trailing edge.
  • the coil may be wound or unwound to adjust external bristle length.
  • the array comprises a plurality of clusters of bristles projecting from said plate, said clusters of bristles spaced along the longitudinal length of said panel, wherein said clusters of bristles project from a de- formable surface member, and wherein said surface member is adjustable to vary the projection of said clusters of bristles.
  • the blade is operable to adjust the flexibility of said bristles, to regulate the modulation of noise spectra of said flow modulating profile.
  • the blade comprises at least one collar which is provided about a portion of at least one of said bristles, the blade operable to move said at least one collar along the length of said at least one bristle to adjust the length of the free end of said at least one bristle.
  • the blade comprises at least one collar which is provided about a portion of at least one of said bristle clusters, the blade operable to move said at least one collar along the length of said at least one bristle cluster to adjust the length of the free end of said at least one bristle cluster.
  • the modulation effect of the bristles is related to the length of the free end of the bristles (i.e. the length from the distal tip end of the bristles to the bristle based or the collar), the effective modulation performed by the bristles can be easily adjusted by movement of the collar along the length of the bristles, effectively shortening the bristle length presented at the trailing edge.
  • said at least a first array of projecting flow modulation elements comprises a relatively flexible body, wherein the length of said array is adjustable along the longitudinal axis of the blade.
  • the array may be compressible or expandable along the longitudinal direction. This acts to vary the number of projecting flow modulation elements per unit length of the trailing edge of the blade, thereby providing adjustable noise modulation characteristics of the flow modulating profile.
  • said flow modulation elements are provided on a base, wherein said base has an adjustable length, wherein the spacing between adjacent elements may be varied by adjusting the base length.
  • the projecting flow modulation elements may comprise a plurality of serrations having an elastic/compressible body provided on a moveable base, wherein the bodies of serrations may be compressed or expanded due to movement of the base.
  • the serrations may be arranged to have a concertina-shaped structure, to allow for compression/expansion of the serrations.
  • the projecting flow modulation elements may comprise a plurality of clusters of projecting bristles provided on a moveable base, wherein said bristle clusters may be moved relative to each other due to the movement of the base.
  • the bristle clusters may be moved to be closely adjacent one another, or the distance between adjacent bristle clusters may be increased.
  • said array of projecting flow modulation elements comprises a plurality of flexible hollow tube members extending from said trailing edge.
  • Preferably said flexible containers extend in a spaced parallel relationship from said trailing edge.
  • the blade is operable to regulate a quantity of fluid present in said tube members, to regulate the weight and associated flexibility of said tube members, to accordingly regulate the modulation of noise spectra of said flow modulating profile.
  • the fluid regulated may be gas, water, hydraulic fluid, etc.
  • wind turbine having at least one wind turbine blade as de- scribed above.
  • Fig. 1 shows a wind turbine
  • Fig. 2 shows a schematic view of a wind turbine blade according to the invention
  • Fig. 3 shows a schematic view of an airfoil profile of the blade of Fig. 2;
  • Fig. 4 shows an enlarged cross-sectional perspective view of a translational serrated flow modulation array on a wind turbine blade according to an embodiment of the invention
  • Fig. 5 shows an illustrative view of a passive control system for the translational array of Fig. 5;
  • Fig. 6 shows an enlarged cross-sectional perspective view of a further em- bodiment of translational bristled flow modulation array on a wind turbine blade according to the invention
  • Fig. 7 shows an enlarged cross-sectional perspective view of first and second flow modulation arrays on a wind turbine blade according to a further embodiment of the invention
  • Fig. 8 shows an enlarged view of the first and second arrays of Fig. 7;
  • Fig. 9 shows a plan view of a further embodiment of first and second flow modulation arrays on a wind turbine blade according to the invention, in first and second positions;
  • Fig. 10 shows an enlarged plan view of an actuatable flow modulation array on a wind turbine blade according to a further embodiment of the invention, in first and second actuation states;
  • Fig. 11 shows an enlarged plan view of a second embodiment of an actuatable flow modulation array on a wind turbine blade according to the invention, in first and second actuation states;
  • Fig. 12 shows an enlarged plan view of a third embodiment of an actuatable flow modulation array on a wind turbine blade according to the invention, in first and second actuation states;
  • Fig. 13 shows an enlarged plan view of a fourth embodiment of an actuatable flow modulation array on a wind turbine blade according to the invention, in first and second actuation states;
  • Fig. 14 shows an enlarged plan view of a fifth embodiment of an actuatable flow modulation array on a wind turbine blade according to the invention, in first and second actuation states.
  • Fig. 1 illustrates a conventional modern upwind wind turbine 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 furthest from the hub 8.
  • the rotor has a radius denoted R.
  • Fig. 2 shows a schematic view of a first embodiment of a wind turbine blade 10 according to an embodiment of the invention.
  • 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 furthest 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.
  • the airfoil region 34 also called the profiled region
  • the airfoil region 34 has an ideal or almost ideal blade shape with respect to generating lift
  • 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 is typically constant along the entire root area 30.
  • the transition region 32 has a transitional profile 42 gradually changing from the circular or elliptical shape 40 of the root region 30 to the airfoil profile 50 of the airfoil region 34.
  • the chord length of the transition region 32 typically increases substantially linearly with increasing distance r from the hub.
  • the airfoil region 34 has an airfoil profile 50 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.
  • Fig. 3 shows a schematic view of an airfoil profile 50 of a typical blade of a wind turbine depicted with the various parameters, which are typically used to define the geometrical shape of an airfoil.
  • the airfoil profile 50 has a pressure side 52 and a suction side 54, which during use - i.e.
  • the air- foil 50 has a chord 60 with a chord length c extending between a leading edge 56 and a trailing edge 58 of the blade.
  • the airfoil 50 has a thickness t, which is defined as the distance between the pressure side 52 and the suction side 54. The thickness t of the airfoil varies along the chord 60.
  • the deviation from a symmetrical profile is given by a camber line 62, which is a median line through the airfoil profile 50. The median line can be found by drawing inscribed circles from the leading edge 56 to the trailing edge 58.
  • the median line follows the centres of these inscribed circles and the deviation or distance from the chord 60 is called the camber f.
  • the asymmetry can also be defined by use of parameters called the upper camber and lower camber, which are defined as the distances from the chord 60 and the suction side 54 and pressure side 52, respectively.
  • Airfoil profiles are often characterised by the following parameters: the chord length c, the maximum camber f, the position df of the maximum camber f, the maximum airfoil thickness t, which is the largest diameter of the inscribed circles along the median camber line 62, the position dt of the maximum thickness t, and a nose radius (not shown). These parameters are typically defined as ratios to the chord length c.
  • Fig. 4 an enlarged view of a portion of the wind turbine blade 10 of Fig. 2 is shown, with reference to the elements of the airfoil 50 shown in Fig. 3.
  • the blade 10 further comprises a flow modulation array 70 provided at the trailing edge 58 of the blade 10.
  • the array 70 comprises a base plate 72 which extends along a portion of the blade trailing edge 58 and a plurality of serrations 74 which project from the base plate 72.
  • the serrations 74 substantially project in a direction away from the leading edge 56 of the blade 10, substantially in line with the mean flow direction at the trailing edge 58 of the blade 10.
  • the serrations 74 act as flow modulation elements, to modulate a boundary layer air- flow at the trailing edge of the wind turbine blade, in order to mitigate, frequency shift, or eliminate noise generated at the trailing edge of the wind turbine blade.
  • the serrations 74 present a flow modulating profile at the trailing edge 58, the particular profile presented operable to modulate the airflow at the blade trailing edge 58, to reduce noise during wind turbine operation due to turbulent airflow at the trailing edge 58 of the blade 10.
  • the array 70 is provided over at least a portion of the trailing edge 58 of the blade 50, preferably in or around the section of the blade 10 along approximately the outer 60-100% length of the blade 10 from the root end 16 of the blade 10.
  • the array 70 is spaced from the tip end 14 of the blade 10 by approximately 5 centimetres.
  • the array 70 is translationally moveable relative to the trailing edge 58 of the blade 10, along any combination of the X, Y, and/or Z-axis with respect to the trailing edge 58.
  • the translational movement of the array 70 allows for the adjustment of the modulation profile presented at the trailing edge, which can allow for the variation of the noise modulation performed.
  • the array 70 may be moveable along only a single axis, but it will be understood that the array may alternatively be configured to move along two if not all three axes.
  • the array 70 by moving the array 70 along the X-axis (i.e. in a direction substantially parallel to the direction of the chord 60 or camber line 62 of the blade 10), the length by which the serrations 74 project beyond the blade trailing edge 58 can be varied, and the array 70 may even be retracted to a position where nothing of the serration 74 extends beyond the trailing edge 58.
  • the length by which the serrations 74 project beyond the trailing edge 58 is increased, which provides for an improved noise-reducing effect at relatively higher speeds of airflow over the blade.
  • retracting the array 70 in the direction of the leading edge 56 reduces the effective length of the serrations 74 beyond the trailing edge 58, thereby providing effective modulation of the noise during turbine operation at relatively lower wind speeds.
  • the array 70 by moving the array 70 along the Y-axis (i.e. in a direction substantially par- allel to the longitudinal axis of the blade 10), it is possible to move the array 70 to provide flow modulation at different positions along the length of the blade 10. Further, by moving the array 70 along the Z-axis (i.e. in a direction substantially perpendicular to the longitudinal axis and the chordal axis of the blade 10), it is possible to adjust the positioning of the array 70 with respect to the pressure and suction sides of the blade 52,54, and accordingly the vary whether the array 70 and the associated flow modulating profile performs primarily a modulation of the pressure side flow, the suction side flow, or some combination of the two.
  • the blade 10 may further comprise at least one linear actuator (not shown) coupled to the array 70, the at least one actuator regulated by a suitable controller (not shown) which is operable to adjust the positioning of the array 70 as required due to operating conditions of the associated wind turbine (e.g. wind speed at the turbine, detected noise levels at the turbine, required noise limited due to time of day, etc.).
  • a suitable controller not shown
  • the blade 10 may comprise a passive control system (not shown) which is operable to vary the positioning of the array 70 without external control signals.
  • Figs. 5(a) and (b) show an illustrative example of a sample passive control system, with reference to an enlarged sectional plan view of a portion of a wind turbine blade.
  • a plurality of pins 76 project from the base plate 72 of the array 70, said pins 76 received within rails 78 provided in the blade 10.
  • the rails 78 extend at an angle to the longitudinal direction of the blade 10, substantially parallel to the chordal plane of the blade.
  • the rails 76 are arranged such that the array 70 is moveable from a first position with said pins 76 located at a first end of said rails 78 (as seen in Fig. 5(a)), to a second position where said pins 76 are located at a second end of said rails 78 (as seen in Fig. 5(b)).
  • the base plate 72 of the array 70 In said first position, the base plate 72 of the array 70 is spaced from the trailing edge 58 of the blade 10, such that the serrations 74 of the array 70 do not project beyond the trailing edge 58 of the blade 10. In said second position, the base plate 72 of the array 70 is positioned closely adjacent to the blade trailing edge 58, such that the serrations 74 project substantially fully beyond the trailing edge 58.
  • the blade 10 further comprises at least one biasing element 80, the biasing element 80 coupled between the base plate 72 of the array 70 and a mounting flange 82 provided on the body of the blade 10.
  • the biasing element 80 may be any spring element, or any other suitable biasing means.
  • the biasing element 80 is operable to bias the array 70 towards said first, at rest, position, away from said second, deployed, position.
  • This centrifugal force (indicated by arrow F in Fig. 5(b)) will act to move the array 70 along the rails 78 from the first at rest position towards the second deployed position, as the magnitude of the centrifugal force increases and gradually overcomes the biasing force of the biasing element 80.
  • the position of the array 70 with respect to the blade trailing edge 58 is varied - in this case, the effective length of the serrations 74 which project beyond the trailing edge 58 of the blade 10 is increased as wind speed increases. This acts to provide more effective modulation of the airflow around the blade for the particular wind speed experienced, and consequently provides improved adaptive noise reduction during operation of the wind turbine.
  • the passive control system illustrated in Fig. 5 may be pro- vided substantially on the exterior of the blade 10 (e.g. for ease of installation/retrofitting to existing blades), or provided substantially on the exterior of the blade 10 (e.g. to reduce drag).
  • the length of serrations 74, biasing element, and/or rails may be configured such that some portion of the serrations 74 project beyond the trailing edge 58 when in the at rest position.
  • biasing element or weighting of the array 70 may be used, e.g. while the biasing element in Fig. 5 is configured to expand as the array 70 moves away from the leading edge 56 and towards the trailing edge 58, alternatively the biasing element may be provided between the array 70 and the trailing edge 58, and con- figured to compress as the array 70 moves towards the trailing edge 58.
  • the biasing or spring force can be selected to ensure that the maximum deployment occurs when the centrifugal force corresponds with the rated upper operational wind speed of the turbine.
  • the array 70 may be configured to oscillate back and forth in a vibrational movement between first and second positions along any combination of the X,Y and Z-axes, during rotation of the wind turbine blade 10. Such vibration of the array 70 may to provide increased modulation of the airflow at the trailing edge 58 of the blade 10, and accordingly increased noise reduction performance of the presented flow modulating profile.
  • translationally moveable array 70 allows for a continually varied adjustment of the flow modulating performance of the presented trailing edge profile, provid- ing for an adaptive reduction of noise generated by wind turbine blade during wind turbine operation.
  • the array 71 comprises a base plate 73 which extends along a portion of the blade trailing edge 58.
  • a plurality of bristle elements 75 project from the base plate 73.
  • the bristles 75 substantially project in a direction away from the leading edge 56 of the blade 10, substantially in line with the mean flow direction at the trailing edge 58 of the blade 10.
  • the bristles 75 comprise a set of closely placed threads, and act as an energy absorbent or damping element at the blade trailing edge 58.
  • the bristles 75 act to reduce the noise levels generated at the trailing edge 58 of the blade 10 during turbine operation by modulating the airflow at the trailing edge 58.
  • the array 71 comprising bristles 75 may be transla- tionally moved along any combination of the X, Y and/or Z-axes, and the considerations outlined with respect to the serrated array 70 may also be applied to the bristled array 71.
  • the length by which the bristles 75 project beyond the trailing edge 58 may be varied, which may affect the flow modulation performed due to exposed length, flexibility due to adjusted length, etc.
  • Fig. 7 a further embodiment of a wind turbine blade 10 according to the invention is shown. In Fig.
  • the blade 10 comprises a first flow modulation array 70a and a second flow modulation array 70b provided at the trailing edge 58 of the blade 10.
  • the arrays 70a,70b comprise respective base plates 72a,72b which extend in a closely adjacent parallel relationship along a portion of the blade trailing edge 58.
  • the arrays 70a,70b respectively further comprise first and second pluralities of serrations 74a,74b which project from the base plates 72a,72b in a direction away from the leading edge 56 of the blade 10, substantially in line with the mean flow direction at the trailing edge 58 of the blade 10.
  • a flow modulating profile at the trailing edge 58 is formed by a combination of the first and second serrations 74a,74b at the trailing edge 58.
  • the profile presented by the combination of the arrays 70a,70b is operable to modulate the airflow at the blade trailing edge 58, to reduce noise during wind turbine operation due to turbulent airflow at the trailing edge 58 of the blade 10.
  • the arrays 70a,70b are provided over at least a portion of the trailing edge 58 of the blade 50, preferably in or around the section of the blade 10 along the outer 60-90% length of the blade 10 from the root end 16 of the blade 10.
  • At least one of said first and second arrays 70a,70b is translationally moveable relative to the trailing edge 58 of the blade 10, along any combination of the X, Y, and/or Z- axis with respect to the trailing edge 58.
  • the translational movement of the array 70a,70b allows for the adjustment of the modulation profile presented at the trailing edge, which can allow for the variation of the noise modulation performed.
  • at least one of said first and second arrays 70a,70b is moveable relative to the other of said arrays 70a,70b, such that the serrated profile which is presented at the trailing edge 58 may be adjusted based on a relative movement between the serrations 74a,74b of the first and second arrays 70a,70b.
  • the first and second arrays 70a,70b are positioned in a first arrangement such that the serrations 74a of the first array 70a project in line with the serrations 74b of the second array 70b.
  • the flow modulating profile presented at the trailing edge 58 of the blade 10 comprises a serrated profile, having a distance L between the distal tip ends of adjacent serrations equivalent to the distance between serrations of the first and second arrays 70a,70b.
  • the first array 70a has been moved along the Y-axis (i.e.
  • the serrated flow modulating profile presented at the blade trailing edge 58 is modified, with the effect that the distance between the distal tip ends of adjacent serrations of the pro- file is now L/2.
  • the modulation provided by the profile of Fig. 8(b) is adjusted relative to the modulation of the profile of Fig. 8(a), due to variations between the inter-serration distance.
  • the serrations 74a of the first array 70a are substantially identical to the serrations 74b of the second array 70b.
  • the serrations 74a of the first array 70a may have a longer serration length and/or serration angle than the serrations 74b of the second array 70b.
  • the first serrations 74a have a serration length of LI and the second serrations 74a have a serration length of L2, LI > L2. Accordingly, through relative motion of the arrays 70a,70b, different modulation effects may be produced dependent on the profile which is presented at the trailing edge.
  • the first array 70a is retracted relative to the second array 70b (the serrations 74a of the first array 70a shown in outline), with the result that the flow modulat- ing profile presented at the trailing edge 58 is a serrated profile having a serration length of L2.
  • the relatively longer serrations 74a of the first array 70a project beyond the serrations 74b of the second array 70b - see Fig. 9(b) - such that the flow modulating profile presented at the trailing edge 58 is a serrated profile having a relatively longer serration length of LI .
  • the movement of the first array 70a may be accomplished using an active and/or a passive control system (not shown).
  • first and second arrays 70a,70b may comprise any suitable flow modulating elements other than serrations, for example an array of bristles extending substantially along the entire length of the array and/or individual clusters of bristles spaced along the length of the array.
  • said first array 70a may comprise a serrated array
  • said second array 70b may comprise a bristled array, wherein the type of modulation performed at the trailing edge 58 of the blade 10 (i.e. modulation using serrations, modulation using bristles, or some combination of the two) may be selected by relative movement be- tween the arrays to advance or retract a preferred array at the trailing edge.
  • the arrays may comprise a plurality of individual array sections provided along at least a portion of the length of the blade 10, said individual sections operable to be separately moveably controlled. This allows for different varia- tion of the noise modulation performed for different sections of the wind turbine blade 10 along the blade length.
  • a plan view of a section of a flow modulating array for a wind turbine blade trailing edge is shown, indicated at 90.
  • the array 90 may be provided along at least a portion of the trailing edge 58 of a blade, and comprises a base plate 92, and a plurality of projecting flow modulation elements in the form or serrations 94 projecting therefrom.
  • the serrations 94 have an inter-serration distance be- tween the distal tip ends 94a of adjacent serrations 94 of Dx, indicated in Fig. 10(a).
  • the serrations 94 are arranged to substantially project in a direction away from the leading edge 56 of the blade 10, substantially in line with the mean flow direction at the trailing edge 58 of the blade 10.
  • the array 90 further comprises a plurality of actuatable members 96 provided in the space defined between adjacent serrations 94 of the array 90.
  • the actuatable members 96 are operable to be altered from a first withdrawn state, indicated in Fig. 10(a), to a second deployed state, indicated in Fig. 10(b).
  • the members 96 are substantially deflated or retracted against the surface of the adjacent serrations 94 and the base plate 92, such that the flow modulating profile presented at the trailing edge 58 of the blade 10 is a substantially serrated profile characterised by an inter- serration distance of Dx.
  • the members 96 On actuation of the members 96, the members 96 deploy or inflate to said second deployed state, wherein the members 96 project away from the base plate 92.
  • the actuatable members 96 are arranged to have a substantially diamond shape when deployed.
  • the free ends 96a of the members 96 present a pointed end similar to the distal ends 94a of the serrations 94, the free ends 96a of the serrations located approximately equidistant from the distal tip ends 94a of adjacent serrations 94. Accordingly, when the members 96 are fully actuated, the flow modulating profile presented at the trailing edge 58 of the blade 10 is a substantially serrated profile characterised by an inter-serration distance of Dx/2.
  • the geometrical shape of the presented flow modulating profile can be adjusted to provide for a varied modulation effect of the noise generated at the trailing edge 58.
  • the actuatable members 96 may be configured to have any suitable shape when actuated, and are not limited to the diamond shape as shown in Fig. 10(b).
  • the serrations 194 may be spaced a distance L from each other along the length of the base plate 192, having an inter-serration distance between the distal tip ends 194a of the adjacent ser- rations 194 of Dy.
  • the actuatable members 196 may be provided on the base plate 192 in the space L between adjacent serrations 194, and have a substantially triangular shape when deployed. Accordingly, the members 196 are operable to be varied from an initial undeployed state close to the base plate 192 (shown in Fig. 11(a)), to an actuated deployed state projecting away from the base plate 192 (shown in Fig. 11(b)). In the deployed state, the free ends 196a of the members 196 are located substantially equidis- tant from the distal ends 194a of the serrations 194.
  • the flow modulating profile presented at the trailing edge 58 of the blade 10 can be varied from a substantially serrated profile characterised by an inter- serration distance of Dy, to a profile having an inter-serration distance of Dy/2, again providing for variable noise modulation through regulation of the characteristics of the flow modulating profile.
  • a plurality of inflatable members may be positioned in the inter-serration distance L, such when the members are actuated, the number of serrations per unit length of the array is more than doubled.
  • actuatable members 296 are provided on at least a portion of the outer surface of the serrations 294, the members 296 actuatable between a first state (shown in Fig. 12(a)) and a second state (shown in Fig. 12(b)).
  • the members 296 are deflated or rest undeployed closely adjacent the surface of the serrations 294, while in the second state the member 296 extend from the surface of the serrations 294 to provide adjusted serrated projections projecting from the base plate 292.
  • the adjusted serrated projections, formed by the serrations 294 and the actuated members 296, have an effective serration length of S2 to the tip end 296a of the members 296 , wherein S2 > SI . Accordingly, the flow modulating profile presented at the trailing edge 58 of the blade 10 can be varied to provide for improved modulation of noise at higher wind speeds (due to longer effective serrations).
  • the actuatable members 96,196,296 may be formed by any suitable actuation device, e.g. a flexible inflatable member, or a piezoelectric surface.
  • the members 96,196,296 may be operable to be inflated using e.g. hydraulic fluid, water, ambient air, etc.
  • the actuation state of the members 96,196,296 may be tunable to an intermediate position between the first undeployed state and the second deployed state, depending on modulation requirements.
  • the actuation of the mem- bers 96, 196,296 may be passively and/or actively controlled.
  • the shape of the actuatable members 96,196,296 when actuated may be any shape suitable to provide a noise modulation at the trailing edge of a wind turbine blade, e.g. the deployed serrations may have a circular shape, square shape, etc. This may allow for a variation in the overall flow modulation profile, e.g. in the embodiment of Fig. 11, this could lead to a combination of triangular serrations interspersed with, say, semi-circular serrations.
  • the actuatable members 96,196,296 may be operable to provide an array having a different shape of general serrations, e.g. in the embodiment of Fig. 12, this could lead to a change in the serra- tion profile from triangular serrations to, say, semi-circular projections.
  • a further embodiment of the invention is shown wherein the characteristics of the flow modulating profile can be varied to provide for adjustable modulation of noise at the trailing edge of a wind turbine blade.
  • a plan view of a section of an array 100 which can be provided at the trailing edge 58 of a wind turbine blade 10 is shown.
  • the array 100 comprises a base plate 102, and a plurality of bristles indicated generally at 104 depending therefrom.
  • the bristles 104 have a bristle length Lb from the base plate 102 to a free end 104a of the bristles, and are provided in individual clusters 106 of a subset of bristles 104 spaced along the length of the base plate 102.
  • the clusters 106 are preferably substantially circular in cross-section, but may be any suitable arrangement, e.g. a planar cross- section.
  • the bristles 104 are operable to perform a modulation of noise generated at the trailing edge 58 of a wind turbine blade 10 by performing an effective damping of the boundary layer flow at the trailing edge 58. Such a modulation effect is dependent on characteristics such as bristle length, bristle flexibility, etc.
  • a plurality of collar members 108 are advanced from the base plate 102, each collar member 108 provided around the circumference of an individual bristle cluster 106.
  • the collar members 108 are dimensioned to snugly fit about the bristle clusters 106, to retain the individual bristles 104 in each cluster 106 in a relatively tight hold within the circumference of the collar 108. Accordingly, the effective free length of the bristles 104 is reduced, from the initial total length of the bristles Lb, to the length Lf from the distal end of the collar 108 to the free end 104a of the bristles 104.
  • the modulation effect performed by the bristles 104 is related to the bristle length
  • the effec- tive length of the bristles 104 is reduced, and accordingly the modulation effect of the array 100 may be regulated.
  • the distance by which the collar members 108 are advanced along the bristles 104 may be controlled as required, in order to provide for the desired modulation effect of the noise at the wind turbine blade trailing edge 58. It will be understood that the regulation of effective bristle length may also be performed for an array wherein bristles are provided along the entire length of the array (e.g. as in the array of Fig. 6).
  • the individual collar members 108 may be replaced by an extended collar member in the form of a pair of bars substantially equivalent in length to the length of the array and provided at either side of the array.
  • the bars may be operable to be advanced in a relatively tight engagement about the bristles of the array to reduce the effective length of the bristles, and accordingly to vary the noise modulation performed by the bristles.
  • Fig. 14 illustrates an enlarged plan view of an individual bristle cluster 206 comprising a plurality of bristles 204 which may be provided as one of a plurality of clusters 206 spaced along the length of a base plate 202 of the array 200.
  • the bristles 204 of the bristle cluster 206 extend from a flexible mounting surface 208 which is provided on the base plate 202 projecting away from the base plate 202.
  • the shape of the mounting surface 208 is deformable, and can be varied from a first deployed state shown in Fig. 14(a), to a second collapsed state shown in Fig.
  • the mounting surface 208 When in said deployed state, the mounting surface 208 forms a substantially smooth dome-shaped surface on the base plate 202, while when in said collapsed state the mounting surface 208 forms a dimpled or ruffled surface, having at least one central dimple 210 which extends towards the base plate 202.
  • the bristles 204 of the cluster 206 are distributed substantially evenly across said mounting surface 208. Accordingly, when the mounting surface 208 is in the deployed state, the dome-shaped mounting surface 208 arranges the bristles 204 of the cluster 206 in a fanned, spaced arrangement at the trailing edge 58 of the blade 10, as seen in Fig. 14(a), the bristles 204 projecting radially away from the centre of the notional sphere formed by the dome of the mounting surface 208.
  • the deformation of the mounting surface 208 to form at least one central dimple 210 on the mounting sur- face 208 results in a close bunching together of the bristles 204 of the cluster 206, as seen in Fig. 14(b), the bristles 204 projecting from the undulating mounting surface 208 along a variety of intersecting paths.
  • the modulation effect provided by the array 200 can be related to the freedom of movement of the bristles 204, the effective variation of the distribution of bristles 204 in a cluster 206 allows for the regulation of the modulation performed by the array 200.
  • the mounting surface may comprise a rela- tively flexible membrane, a cavity defined between the membrane and the base plate, wherein a pressurised fluid or a vacuum may be applied to said cavity to inflate/deflate the membrane.
  • a pressurised fluid or a vacuum may be applied to said cavity to inflate/deflate the membrane.
  • regulation of the state of the mounting surface may be controlled passively and/or actively as appropriate.
  • the invention may also apply for an array wherein bristles are provided along the entire length of the array (e.g. as in the array of Fig. 6).
  • the individual mounting surface for each bristle cluster may be replaced by an extended flexible mounting surface which extends along a substantial portion of the length of the base plate of an array.
  • Such an extended flexible mounting surface may be deformable between deployed and collapsed states, wherein the mounting surface has a cross-section substantially equivalent to the views of the mounting surface 208 shown in Fig. 14, such that the spatial distribution, and associate modulation effect, of the bristles may be regulated as required.
  • the blade may additionally or alternatively comprise a passive actuation system, wherein an open duct is provided towards the leading edge of the wind turbine blade.
  • the duct is arranged to collect a volume of air during rotation of the blade, and to channel said air towards the flow modulating profile provided at the trailing edge.
  • the air may then be used to inflate an actuation member provided as part of a trailing edge flow modulation array, as may be described in any of the embodiments recited herein.
  • the volume of air collected by the duct may be dependent on the rotational speed of the wind turbine blade and/or the incident airflow at the blade, and accordingly the actuation state of the trailing edge array may be adaptive depending on the operating conditions of the wind turbine.
  • An additional or alternative method of regulating the modulation effect of a bristled array may comprise the provision of flexible tube or finger members on a base plate of an array for provision at the trailing edge of a wind turbine blade.
  • the tube members may be dimensioned to vibrate or flutter during motion of the wind turbine blade, such that the tube members act to modulate the airflow at the trailing edge.
  • the flexible tube members are operable to receive a fluid within an internal cavity defined in the tube members, wherein the quantity of fluid provided in said tube members may be varied. Accordingly, the weight and associated flexibility of said tube members may be varied, and any modulation effect associated with said tube members may be controlled by regulating the volume and/or pressurisation of the fluid provided in the tube members.
  • a flow modulation array for a wind turbine blade may comprise a flexible membrane provided at the trailing edge of the wind turbine blade, and at least one actuator coupled to said flexible membrane, wherein the membrane may be deformed using the actuator to vary the shape of the membrane presented at the trailing edge of the blade.
  • the blade may comprise a plurality of arm members coupled to said membrane, wherein each of said arm members individually actuatable to be moved relative to the trailing edge of the blade to adjust the shape of said flexible membrane provided at said trailing edge.
  • the general shape of the flexible membrane can be controlled by the relative movement of the arm members - this allows for a regular or irregular flow modulating profile to be presented at the trailing edge.
  • the arm members may be advanced from or retracted into the blade body, acting to vary or stretch the profile of the flexible membrane surface.
  • the flexible membrane may stretch to form a serrated or corrugated surface. Accordingly, the dimensions of such a serrated surface (e.g. serration length, and associated angle of the serrations) may be varied based on the extent by which the arm members are extended beyond the blade trailing edge.
  • said plurality of arm members may be coupled to an actuation bar to provide for simultaneous actuation of said arm members.
  • a flow modulation array may be configured such that the projecting flow modulation elements of the array (which may include e.g. serrations, bris- ties, bristle clusters) are provided on a flexible base plate, which may be expanded or compressed in a direction substantially parallel to the longitudinal axis of the blade, to vary the distribution of the projecting flow modulation elements in the array.
  • the array may be configured to vary the spacing between adjacent elements, and/or the shape of the elements themselves may be deformed as a result of the compression/expansion of the base plate. Accordingly, the elements (e.g.
  • serrations may have an elastic or compressible body provided on the base, wherein the bodies of serrations may be compressed or expanded due to movement of the base. This allows for the serrations to have a concertina-shaped structure, to allow for compression/expansion of the serrations.
  • the variation of the distribution of elements in the array means that the flow modulating profile presented at the blade trailing edge can be adjusted, to provide for variation of the modulation performed by the profile at the blade trailing edge. It will be understood that the features of any one of the above embodiments may be combined with any of the other embodiments, to increase the effectiveness of the overall system, e.g. the translational array of Fig. 4 may be combined with the actuatable members of the embodiment of Fig. 12 to provide for additional flexibility of modulation control.
  • the variation of the modulation performed at the trailing edge of the wind turbine blade may be actively controlled, preferably through use of a closed-loop control system.
  • the flow modulating profile of a wind turbine blade is coupled to a controller operable to detect at least one operational characteristic of a wind turbine using the wind turbine blade. This characteristic may be a selected using a combination of any one or more of the following: a general noise level detected at the wind turbine, a noise level associated with a particular wind tur- bine blade, a wind speed at the turbine, a rotational speed of the wind turbine blades of the turbine, etc.
  • the controller is then operable to vary the flow modulating profile of the wind turbine blade to minimise the noise level generated during operation of the wind turbine.
  • the herein described embodiments present a wind turbine blade having an adaptive regulation of the noise produced by such a blade during wind turbine operation. Such regulation may be passively and/or actively controlled, and allows for effective noise control without requiring redesign, replacement and/or retrofitting of noise reducing components to the blade.

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  • Engineering & Computer Science (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Sustainable Development (AREA)
  • Sustainable Energy (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Fluid Mechanics (AREA)
  • Wind Motors (AREA)

Abstract

La présente invention concerne une pale d'éolienne présentant un profil de modulation de flux pouvant être ajusté au niveau du bord de fuite de la pale. Le profil comprend au moins un réseau d'éléments de modulation de flux en saillie qui peuvent agir pour moduler un écoulement d'air et un bruit généré par un écoulement turbulent associé au niveau du bord de fuite. Les éléments du réseau peuvent être ajustés lors du fonctionnement d'une éolienne comprenant une telle pale pour fournir une modulation de bruit contrôlée, qui ne nécessite pas de procédures complexes de nouvelles spécifications et/ou de rattrapage. Des exemples d'ajustements comprennent le déplacement en translation du réseau d'éléments, la variation de la forme d'éléments, la flexibilité et analogues. L'ajustement peut être contrôlé passivement et/ou activement.
PCT/EP2012/069169 2011-09-29 2012-09-28 Pale d'éolienne Ceased WO2013045601A1 (fr)

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
EP11007928.2 2011-09-29
EP11007934 2011-09-29
EP11007934.0 2011-09-29
EP11007928 2011-09-29

Publications (1)

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WO2013045601A1 true WO2013045601A1 (fr) 2013-04-04

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CN104791199A (zh) * 2015-03-24 2015-07-22 北京金风科创风电设备有限公司 叶片尾缘附件及风力发电机组叶片
US9638164B2 (en) 2013-10-31 2017-05-02 General Electric Company Chord extenders for a wind turbine rotor blade assembly
EP3181895A1 (fr) * 2015-12-17 2017-06-21 LM WP Patent Holding A/S Système à plaque de séparation pour une pale de turbine éolienne dentelée
EP3348825A1 (fr) 2017-01-12 2018-07-18 LM WP Patent Holding A/S Pale d' éolienne comprenant un dispositif de réduction de bruit de bord de fuite
US10746157B2 (en) 2018-08-31 2020-08-18 General Electric Company Noise reducer for a wind turbine rotor blade having a cambered serration
US10767623B2 (en) 2018-04-13 2020-09-08 General Electric Company Serrated noise reducer for a wind turbine rotor blade
WO2022012970A1 (fr) * 2020-07-13 2022-01-20 Siemens Gamesa Renewable Energy A/S Moyen de réduction de bruit destiné à une pale d'éolienne, pale d'éolienne, éolienne, et procédé de réduction de bruit destiné à une pale d'éolienne
CN114738319A (zh) * 2022-04-20 2022-07-12 浙江尚扬通风设备有限公司 低噪声轴流风机及其使用方法
CN115095474A (zh) * 2022-05-11 2022-09-23 大唐安徽发电有限公司新能源分公司 一种多结构组合的叶片降噪锯齿尾缘及安装方法
CN116075634A (zh) * 2020-09-08 2023-05-05 西门子歌美飒可再生能源公司 风力涡轮机和用于风力涡轮机的降噪方法
EP4306796A1 (fr) * 2022-07-11 2024-01-17 Wobben Properties GmbH Procédé permettant d'influencer l'émission sonore d'une pale de rotor d'éolienne
EP4306795A1 (fr) * 2022-07-11 2024-01-17 Wobben Properties GmbH Procédé d'optimisation d'une pale de rotor d'éolienne

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WO2002051730A2 (fr) * 2000-12-23 2002-07-04 Aloys Wobben Pale de rotor pour eolienne
WO2008003330A1 (fr) * 2006-07-07 2008-01-10 Danmarks Tekniske Universitet (Technical University Of Denmark) géométrie à section de bord de fuite variable pour pale d' éolienne
US20080166241A1 (en) 2007-01-04 2008-07-10 Stefan Herr Wind turbine blade brush
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Cited By (21)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US9638164B2 (en) 2013-10-31 2017-05-02 General Electric Company Chord extenders for a wind turbine rotor blade assembly
CN104791199A (zh) * 2015-03-24 2015-07-22 北京金风科创风电设备有限公司 叶片尾缘附件及风力发电机组叶片
EP3390812B1 (fr) 2015-12-17 2020-07-22 LM WP Patent Holding A/S Système à plaque de séparation pour une pale de turbine éolienne dentelée
EP3181895A1 (fr) * 2015-12-17 2017-06-21 LM WP Patent Holding A/S Système à plaque de séparation pour une pale de turbine éolienne dentelée
WO2017103192A1 (fr) * 2015-12-17 2017-06-22 Lm Wp Patent Holding A/S Agencement de plaque de séparation pour pale d'éolienne dentelée
US11067057B2 (en) 2015-12-17 2021-07-20 Lm Wp Patent Holding A/S Splitter plate arrangement for a serrated wind turbine blade
WO2018130651A1 (fr) 2017-01-12 2018-07-19 Lm Wind Power International Technology Ii Aps Pale d'éolienne dotée d'un dispositif de réduction du bruit de bord de fuite
EP3348825A1 (fr) 2017-01-12 2018-07-18 LM WP Patent Holding A/S Pale d' éolienne comprenant un dispositif de réduction de bruit de bord de fuite
US10767623B2 (en) 2018-04-13 2020-09-08 General Electric Company Serrated noise reducer for a wind turbine rotor blade
CN112585350A (zh) * 2018-08-31 2021-03-30 通用电气公司 具有弧形锯齿的用于风力涡轮转子叶片的消音器
US10746157B2 (en) 2018-08-31 2020-08-18 General Electric Company Noise reducer for a wind turbine rotor blade having a cambered serration
CN115803522A (zh) * 2020-07-13 2023-03-14 西门子歌美飒可再生能源公司 用于风力涡轮机叶片的降噪装置、风力涡轮机叶片、风力涡轮机以及用于风力涡轮机叶片的降噪的方法
WO2022012970A1 (fr) * 2020-07-13 2022-01-20 Siemens Gamesa Renewable Energy A/S Moyen de réduction de bruit destiné à une pale d'éolienne, pale d'éolienne, éolienne, et procédé de réduction de bruit destiné à une pale d'éolienne
US11384732B2 (en) 2020-07-13 2022-07-12 Siemens Gamesa Renewable Energy A/S Noise reduction means for a wind turbine blade, wind turbine blade, wind turbine, and method for noise reduction for a wind turbine blade
CN116075634A (zh) * 2020-09-08 2023-05-05 西门子歌美飒可再生能源公司 风力涡轮机和用于风力涡轮机的降噪方法
CN114738319A (zh) * 2022-04-20 2022-07-12 浙江尚扬通风设备有限公司 低噪声轴流风机及其使用方法
CN114738319B (zh) * 2022-04-20 2023-11-14 浙江尚扬通风设备有限公司 低噪声轴流风机及其使用方法
CN115095474A (zh) * 2022-05-11 2022-09-23 大唐安徽发电有限公司新能源分公司 一种多结构组合的叶片降噪锯齿尾缘及安装方法
CN115095474B (zh) * 2022-05-11 2025-09-09 大唐安徽发电有限公司新能源分公司 一种多结构组合的叶片降噪锯齿尾缘及安装方法
EP4306796A1 (fr) * 2022-07-11 2024-01-17 Wobben Properties GmbH Procédé permettant d'influencer l'émission sonore d'une pale de rotor d'éolienne
EP4306795A1 (fr) * 2022-07-11 2024-01-17 Wobben Properties GmbH Procédé d'optimisation d'une pale de rotor d'éolienne

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