Wind turbine blade and wind turbine

Abstract

A wind turbine blade, comprising a sensor device for detecting properties of flow-induced noise produced by the blade and an actuator device for emitting an anti-noise signal for at least partially cancelling out the flow-induced noise, wherein the actuator device comprises an aerodynamically shaped housing attached to an outer surface of the blade. The aerodynamically shaped housing of the actuator device reduces a deterioration the aerodynamic efficiency of the blade. Further, the generation of turbulences at sharp edges of the housing is avoided.

Claims

1. A wind turbine blade, comprising: a sensor device for detecting properties of flow-induced noise produced by the blade; and an actuator device for emitting an anti-noise signal for at least partially cancelling out the flow-induced noise, wherein the actuator device includes an aerodynamically shaped housing that is a symmetric airfoil such that a first side of the housing and a second side of the housing are symmetric to each other with respect to a chord line connecting a leading edge of the housing and a trailing edge of the housing, the housing being attached at one of a suction side and a pressure side of the blade such that a distance between the housing and a trailing edge of the blade is shorter than a distance between the housing and a leading edge of the blade, at least one diaphragm, wherein a first surface of the at least one diaphragm is exposed at an outer surface of the housing for converting kinetic energy into acoustic energy for generating the anti-noise signal such that a sound wave is generated by the moving diaphragm and emitted by the actuator device, and at least one closed gas chamber accommodated inside the housing configured to increase acoustic radiation efficiency of the sound wave generated by the moving diaphragm and emitted by the actuator device such that a second surface of the at least one diaphragm forms part of an enclosure of the at least one closed gas chamber, wherein the actuator device is attached to an attachment surface of the blade and without using a hole in the blade, wherein a plurality of actuator units are located within the at least one closed gas chamber, and wherein each actuator unit of the plurality of actuator units includes a respective diaphragm for converting kinetic energy into acoustic energy, wherein the at least one gas closed gas chamber includes multiple closed and spaced apart gas chambers, each of the multiple closed and spaced apart gas chamber being associated with a corresponding actuator unit of the plurality of actuator units such that a diaphragm of a respective actuator unit forms part of an enclosure of a respective associated gas chamber; wherein the leading edge of the housing having a tapered section that is concavely shaped in a direction of a leading edge of the blade that is adjacent to a rounded edge that leads to an outer surface of the housing, the trailing edge of the housing having a tapered section that is concavely shaped in a direction of a trailing edge of the blade that is adjacent to a rounded edge that leads to the outer surface of the housing.

2. The wind turbine blade according to claim 1, wherein a total volume of the at least one closed gas chamber is 0.03 liters or more.

3. The wind turbine blade according to claim 1, wherein a fluid flow approaching the housing from the leading edge of the blade is flowing from the leading edge of the housing to the trailing edge of the housing.

4. The wind turbine blade according to claim 3, wherein: the airfoil of the housing divides the fluid flow approaching the housing from the leading edge of the blade at the leading edge of the housing such that: a portion of the fluid flow is flowing from the leading edge of the housing along the one of the suction side and the pressure side of the blade and along the first side of the housing to the trailing edge of the housing, and a further portion of the fluid flow is flowing from the leading edge of the housing along the one of the suction side and the pressure side of the blade and along the second side of the housing to the trailing edge of the housing.

5. The wind turbine blade according to claim 1, wherein: the leading edge of the housing is arranged upstream and the trailing edge of the housing is arranged downstream both with respect to a fluid flow along the one of the suction side and the pressure side of the blade.

6. The wind turbine blade according to claim 1, wherein the airfoil is in a plane being arranged parallel to the attachment surface of the blade and/or parallel to a tangent to the attachment surface of the blade.

7. The wind turbine blade according to claim 1, wherein the housing has rounded edges at the outer surface of the housing.

8. The wind turbine blade according to claim 1, wherein the plurality of actuator units comprises multiple actuator units arranged chordwise with respect to a chord line of the blade airfoil and/or with respect to the chord line of the housing.

9. The wind turbine blade according to claim 1, wherein the aerodynamic shaped housing provides for accommodation of the multiple closed and spaced apart gas chambers without significant deterioration of the aerodynamic performance of the blade.

10. The wind turbine blade according to claim 1, wherein the multiple closed and spaced apart gas chambers includes a total volume 0.1 liters or more.

11. The wind turbine blade according to claim 1, wherein the multiple closed and spaced apart gas chambers each include a cuboid shape.

12. The wind turbine blade according to claim 1, wherein the aerodynamic shaped housing provides for accommodation of the multiple closed and spaced apart gas chambers by extending away from an aerodynamically shaped airfoil cross section of the wind turbine blade.

13. The wind turbine blade according to claim 1, further comprising a microphone unit located downstream form the actuator device configured to detect noise properties, and a control located inside the wind turbine blade configured to generate a control signal to each of the plurality of actuator units based on a sensor signal of a microphone unit.

14. A wind turbine, comprising one or more wind turbine blades according to claim 1.

15. A wind turbine blade, comprising: a sensor device for detecting properties of flow-induced noise produced by the blade; and an actuator device for emitting an anti-noise signal for at least partially cancelling out the flow-induced noise, wherein the actuator device includes an aerodynamically shaped housing that is a symmetric airfoil such that a first side of the housing and a second side of the housing are symmetric to each other with respect to a chord line connecting a leading edge of the housing and a trailing edge of the housing, the housing being attached at one of a suction side and a pressure side of the blade such that a distance between the housing and a trailing edge of the blade is shorter than a distance between the housing and a leading edge of the blade, at least one diaphragm, wherein a first surface of the at least one diaphragm is exposed at an outer surface of the housing for converting kinetic energy into acoustic energy for generating the anti-noise signal such that a sound wave is generated by the moving diaphragm and emitted by the actuator device, and at least one closed gas chamber accommodated inside the housing configured to increase acoustic radiation efficiency of the sound wave generated by the moving diaphragm and emitted by the actuator device such that a second surface of the at least one diaphragm forms part of an enclosure of the at least one closed gas chamber, wherein the actuator device is attached to an attachment surface of the blade and without using a hole in the blade; wherein the leading edge of the housing having a tapered section that is concavely shaped in a direction of a leading edge of the blade that is adjacent to a rounded edge that leads to an outer surface of the housing, the trailing edge of the housing having a tapered section that is concavely shaped in a direction of a trailing edge of the blade that is adjacent to a rounded edge that leads to the outer surface of the housing.

16. A wind turbine blade, comprising: a sensor device for detecting properties of flow-induced noise produced by the blade; and an actuator device for emitting an anti-noise signal for at least partially cancelling out the flow-induced noise, wherein the actuator device includes an aerodynamically shaped housing that is a symmetric airfoil such that a first side of the housing and a second side of the housing are symmetric to each other with respect to a chord line connecting a leading edge of the housing and a trailing edge of the housing, the housing being attached at one of a suction side and a pressure side of the blade such that a distance between the housing and a trailing edge of the blade is shorter than a distance between the housing and a leading edge of the blade, at least one diaphragm, wherein a first surface of the at least one diaphragm is exposed at an outer surface of the housing for converting kinetic energy into acoustic energy for generating the anti-noise signal, and at least one closed gas chamber accommodated inside the housing such that a second surface of the at least one diaphragm forms part of an enclosure of the at least one closed gas chamber, wherein the actuator device is attached to an attachment surface of the blade and without using a hole in the blade; wherein the leading edge of the housing having a tapered section that is concavely shaped in a direction of a leading edge of the blade that is adjacent to a rounded edge that leads to an outer surface of the housing, the trailing edge of the housing having a tapered section that is concavely shaped in a direction of a trailing edge of the blade that is adjacent to a rounded edge that leads to the outer surface of the housing.

Description

BRIEF DESCRIPTION

(1) Further embodiments, features and advantages of the present invention will become apparent from the subsequent description and dependent claims, taken in conjunction with the accompanying drawings, in which:

(2) FIG. 1 shows a wind turbine according to an embodiment;

(3) FIG. 2 shows a partial perspective view of a blade of the wind turbine of FIG. 1 according to an embodiment:

(4) FIG. 3 shows the blade of FIG. 2 and a housing of an actuator device attached to a surface of the blade in a cross-section view along line III-III in FIG. 2:

(5) FIG. 4 shows a cross-section view of the housing along line IV-IV in FIG. 3:

(6) FIG. 5 shows a view of a portion of a surface of a blade and a housing according to a further embodiment:

(7) FIG. 6 shows a view similar as FIG. 3, wherein distances of the housing to a leading edge and a trailing edge of the blade are illustrated:

(8) FIG. 7 shows an enlarged view of the housing of the actuator device of FIG. 3, wherein the actuator device comprises one actuator unit and one gas chamber:

(9) FIG. 8 shows a view similar as FIG. 7 but for another embodiment of the actuator device in which the actuator device comprises three actuator units and three gas chambers:

(10) FIG. 9 shows a view similar as FIG. 7 but for another embodiment of the actuator device in which the actuator device comprises three actuator units and one gas chambers; and

(11) FIG. 10 illustrates a volume of a gas chamber of FIG. 7.

(12) In the Figures, like reference numerals designate like or functionally equivalent elements, unless otherwise indicated.

DETAILED DESCRIPTION

(13) FIG. 1 shows a wind turbine 1 according to an embodiment. The wind turbine 1 comprises a rotor 2 having one or more blades 3 connected to a hub 4. The hub 4 is connected to a generator (not shown) arranged inside a nacelle 5. During operation of the wind turbine 1, the blades 3 are driven by wind to rotate and the wind's kinetic energy is converted into electrical energy by the generator in the nacelle 5. The nacelle 5 is arranged at the upper end of a tower 6 of the wind turbine 1. The tower 6 is erected on a foundation 7 such as a monopile or concrete foundation. The foundation 7 is connected to and/or driven into the ground or seabed.

(14) FIG. 2 shows a partial perspective view of a blade 3 of the wind turbine 1 of FIG. 1 according to an embodiment.

(15) The blade 3 comprises a sensor device 8 and an actuator device 9 for active-noise cancellation of flow-induced noise 10 produced by the blade 3. The main noise source of a blade 3 is so-called trailing edge noise 10 generated at a trailing edge 14 of the blade 3.

(16) As shown in FIG. 2, the blade 3 comprises an aerodynamically shaped cross-section profile (blade airfoil 12). The blade airfoil 12 includes a leading edge 13 and a trailing edge 14. Furthermore, the blade airfoil 12 includes a suction side 15 and a pressure side 16 connected with each by the leading and trailing edges 13, 14. A chord line 17 of the blade airfoil 12 is connecting the leading edge 13 with the trailing edge 14.

(17) Further, the blade 3 comprises a shell 18. The shell 18 is, for example, made from fiber-reinforced resin.

(18) The shell 18 comprises a suction side shell 19 and a pressure side shell 20. The suction and pressured side shells 19, 20 are surrounding an inner cavity 21 of the blade 3.

(19) The sensor device 8 is configured for detecting properties (e.g., characteristics) of the flow-induced noise 10 produced by the blade 3. The sensor device 8 comprises, for example, several sensor units 22 for detecting the properties of the flow-induced noise 10. As an example, in FIG. 2 three sensor units 22 are shown. However, the sensor device 8 may also include more or less than three sensor units 22.

(20) The sensor device 8 and/or each sensor unit 22 comprises, for example, a microphone for detecting the properties of the noise 10. However, the sensor device 8 and/or each sensor unit 22 may also comprise other means for detecting the properties of the noise 10.

(21) The actuator device 9 is configured for emitting an anti-noise signal 23. The anti-noise signal 23 is generated by the actuator device 9 for, at least partially, cancelling out the flow-induced noise 10.

(22) The actuator device 9 comprises, for example, one or more loudspeaker or other means for generating the anti-noise signal 23.

(23) The actuator device 9 has an aerodynamically shaped housing 24 attached to an outer surface 25 of the blade 3. In the example of FIG. 2, the housing 24 of the actuator device 9 is attached to the outer surface 25 of the suction side shell 19 of the blade 3. While not shown in the figures, in other examples, the housing 24 of the actuator device 9 may also be attached to an outer surface 26 (FIG. 3) of the pressure side shell 20 of the blade 3.

(24) FIG. 3 shows the blade 3 of FIG. 2 in cross-section, with the cross-section taken along line III-III in FIG. 2.

(25) In FIG. 3, a fluid flow 27 (e.g., air flow 27) along the surfaces 25, 26 of the blade 3 is illustrated. The fluid flow 27 is separated at the leading edge 13 of the blade into two portions 28, 29. A first portion 28 of the fluid flow 27 is guided along the suction side 15 of the blade 3 to the trailing edge 14 of the blade 3. A second portion 29 of the fluid flow 27 is guided along the pressure side 16 of the blade 3 to the trailing edge 14 of the blade 3.

(26) FIG. 3 shows in addition a cross-section view of the housing 24 of the actuator device 9. The housing 24 has rounded edges 30 (FIG. 7). Further, the housing 24 has tapered portions 31 (FIG. 7) tapered in a direction towards the leading edge 13 and in a direction towards the trailing edge 14 of the blade 3 (said directions are directions with respect to a flow path of the flow 28 along the surface 25 of the blade 3).

(27) FIG. 4 shows a cross-section of the aerodynamically shaped housing 24 of the actuator device 9. The cross-section is taken along line IV-IV in FIG. 3. As can be seen in FIG. 4, the housing 24 has an airfoil 32 (e.g., a symmetric airfoil 32) with a leading edge 33 and a trailing edge 34. The housing airfoil 32 further comprises a first side 35 and a second side 36 connected with each other at the leading and trailing edges 33, 34 of the housing 24. A chord line 37 is connecting the leading and trailing edges 33, 34 with each other.

(28) With respect to a fluid flow 28 along the suction side 15 (FIG. 3) of the blade 3 to which the housing 24 is attached, the leading edge 33 of the housing 24 is arranged upstream and the trailing edge 34 of the housing 24 is arranged downstream.

(29) Due to the described configuration of the housing 24 and arrangement of the housing 24 on the blade 3, a flow 28 (FIG. 3) of fluid (e.g., air) is approaching the housing 24 from the leading edge 13 of the blade 3. Further, the fluid flow 28 is meeting the housing 24 at its leading edge 33. At the leading edge 33 of the housing 24, the fluid flow 28 is divided in two portions 38, 39. A first portion 38 of the approaching flow 28 is guided along the first side 35 of the housing 24 to the trailing edge 34 of the housing 24. A second portion 39 of the approaching flow 28 is guided along the second side 36 of the housing 24 to the trailing edge 34 of the housing 24.

(30) In particular, the housing 24 has the aerodynamically shaped cross-section (airfoil 32, FIG. 4) in a plane E (FIG. 7) being arranged parallel to an attachment surface 40 (FIG. 3) of the blade 3. The attachment surface 40 of the blade 3 is, in particular, a surface of the blade 3 to which the housing 24 is attached. In the shown example, the attachment surface 40 is a portion of the suction side surface 25 of the blade 3 (in other examples, it can also be a portion of the pressure side surface 26 of the blade 3). A size S of the attachment surface 40 is, in particular, equal to a footprint F of the housing 24.

(31) In case of a non-flat attachment surface 40 (FIG. 5) of the blade 3, the housing 24 may have the aerodynamically shaped cross-section (airfoil 32, FIG. 4) in a plane E being arranged parallel to a tangent plane T to the attachment surface 40 of the blade 3. The tangent plane T is, in particular, based on a tangent T to the attachment surface 40 in the point P, as seen in the cross-section view of FIG. 5.

(32) As illustrated in FIG. 6, the housing 24 of the actuator device 9 may be attached at the suction side 15 (suction side shell 19) of the blade 3 such that a distance D1 between the housing 24 and the trailing edge 14 of the blade 3 is shorter than a distance D2 between the housing 24 and the leading edge 13 of the blade 3. The distances D1, D2 are distances with respect to a flow path of the respective fluid flow 28 (or 29).

(33) FIG. 7 displays an enlarged view of the housing 24 of the actuator device 9 of FIG. 3. As shown, the actuator device 9 comprises one or more actuator units 41 for generating the anti-noise signal 23 (FIG. 2). The actuator unit(s) 41 is/are at least partially accommodated inside the housing 24. Each actuator unit 41 includes a diaphragm 42 for converting kinetic energy into acoustic energy. The diaphragm 42 is exposed at an outer surface 44 of the housing 24.

(34) Further, each actuator unit 41 includes a driving unit 43 for driving a movement of the diaphragm 41 such that a sound wave and/or pressure wave can be generated by the moving diaphragm 42.

(35) Moreover, as shown in FIG. 7, the actuator device 9 may further comprise at least one (e.g., closed) gas chamber 45 accommodated inside the housing 24. In particular, the diaphragm 42 forms part of an enclosure 46 of the gas chamber 45.

(36) In FIG. 7, an example of an actuator device 9 with one actuator unit 41 and one gas chamber 45 is shown. However, an actuator device 9, 9 may also comprise more than one actuator unit 41 and/or more than one gas chamber 45, as illustrated in FIGS. 8 and 9.

(37) FIG. 8 shows an example of an actuator device 9 with three actuator units 41 and three gas chambers 45. Each actuator unit 41 includes a diaphragm 42 and a driving unit 43.

(38) Furthermore, each gas chamber 45 is associated with one (single) corresponding actuator unit 41 such that a diaphragm 42 of a respective actuator unit 41 forms part of an enclosure 46 of a respective associated gas chamber 45.

(39) FIG. 9 shows an example of an actuator device 9 with three actuator units 41 and one gas chamber 45. Each actuator unit 41 includes a diaphragm 42 and a driving unit 43. For illustration purposes, only for one of the three actuator units 41, the diaphragm 42 and driving unit 43 is denoted with a reference sign. Furthermore, the one big gas chamber 45 is associated with all three actuator units 41 such that the diaphragms 42 of the actuator units 41 form part of an enclosure 46 of the one gas chamber 45.

(40) In embodiments in which the actuator device 9, 9 comprises multiple actuator units 41, 41, the multiple actuator units 41, 41, may be arranged chordwise with respect to the chord line 17 of the blade airfoil 12 (FIG. 3) and/or with respect to the chord line 37 of the housing airfoil 32.

(41) Having the aerodynamically shaped housing 24, 24, 24 of the actuator device 9, 9, 9 allows to accommodate one or more gas chambers 45, 45, 45 with a relatively large total volume V.sub.tot inside the housing 24, 24, 24 without significant deterioration of the aerodynamic performance of the blade 3, 3, 3. With a large total volume V.sub.tot of the gas chamber(s) 45, 45, 45 acoustic radiation losses can be reduced and acoustic radiation efficiency can be improved.

(42) A volume V.sub.1 of the gas chamber 45 (FIG. 7) is, for example, given by the product of its width B, height H and depth T, as shown in FIG. 10. Further, also a volume V.sub.1, V.sub.2, V.sub.3 of each of the three gas chambers 45 in FIG. 8 as well as a volume V.sub.1 of the gas chamber 45 in FIG. 9 may be given as illustrated in FIG. 10.

(43) The gas chambers 45, 45, 45 may have a rectangular block shape (cuboid shape), as shown in FIG. 10. Further, although not shown in figures, any of the gas chambers 45, 45, 45 may also have a different shape than rectangular block shape.

(44) A total volume V.sub.tot=V.sub.1 of the gas chamber 45 (FIG. 7), a total volume V.sub.tot=V.sub.1+V.sub.2+V.sub.3 of the gas chamber 45 (FIG. 8) and/or a total volume V.sub.tot=V.sub.1 of the gas chamber 45 (FIG. 9) has, for example, a value of 0.1 liters or more to provide a sufficient acoustic efficiency of the respective actuator device 9, 9, 9.

(45) For generating the anti-noise signal 23, the wind turbine blade 3 comprises, for example, a control unit 48 (FIG. 2) for generating a control signal A based on a sensor signal B of the sensor device 8. The sensor signal B of the sensor device 8 corresponds, in particular, to the noise 10 of the blade 3. The control unit 48 is configured to control the actuator device 9 by means of the control signal A such that the actuator device 9 emits the anti-noise signal 23. The control unit 48 is, for example, configured to generate the control signal A such that a superposition of the noise 10 and the anti-noise signal 23 leads to a destructive interference.

(46) The actuator device 9 is, for example, connected (wired 49 or wireless) via the control unit 48 with the sensor device 22 for data transfer. The control unit 48 is, for example, arranged inside the blade 3 (i.e. in the inner cavity 21 of the blade 3).

(47) Thus, the described active noise cancellation system (i.e. the sensor and actuator devices 8, 9 and, for example, the control unit 48) allows a significant reduction of a noise emission of the blade 3. By means of the aerodynamically shaped housing 24, this noise reduction can be realized without significantly deteriorating the aerodynamic properties of the blade 3.

(48) Although the present invention has been described in accordance with preferred embodiments, it is obvious for the person skilled in the art that modifications are possible in all embodiments.