Rotor blade with noise reduction device

Abstract

The present invention describes a rotor blade (2) having a leading edge (23) and a trailing edge (24), wherein the rotor blade (2) is designed and configured to be exposed to a fluid flowing substantially from the leading edge (23) to the trailing edge (24), the rotor blade (2) including at least two sensors (31) designed to detect the flow characteristics of the fluid and provide corresponding sensor signals, and the rotor blade (2) further including at least two actuators (32) for generating an anti-noise signal (36) based on the sensor signals, the sensors (31) being arranged along the spanwise direction at a surface of the rotor blade (2), and the actuators (32) being arranged along the chord direction at a surface of the rotor blade (2), and the actuators (32) being arranged and prepared such that flow-induced edge noise (35) of the rotor blade (2) generated by the fluid is at least partially eliminated by the anti-noise signal (36). The present invention further describes a method for forming such a rotor blade, and a related wind turbine.

Description

Technical Field

[0001] This invention relates to a rotor blade with a noise reduction device, particularly for wind turbines. The rotor blade is designed and configured to be exposed to fluids, such as air, wherein the invention minimizes edge noise induced by the flow of the rotor blade. Furthermore, this invention relates to a wind turbine with at least one such rotor blade. Background Technology

[0002] When rotor blades with leading and trailing edges are exposed to a fluid, such as air, that flows substantially from the leading edge to the trailing edge of the rotor blade, noise is typically generated at the edges of the rotor blades, for example, due to eddies. The intensity and frequency of the noise depend on many parameters, such as the properties of the fluid and the properties of the edges, i.e., the size and shape of the edges, such as whether they are rounded or sharp.

[0003] Trailing-edge noise emitted from wind turbine blades is the primary noise-generating mechanism in modern industrial-scale wind turbines. Significant effort and investment have been made in noise reduction technologies, including, for example, sawtooth-shaped blades currently used in new onshore turbines. Noise from wind turbines typically determines the area where the machine can be erected, or consequently, how it can be operated. Wind turbines are often operated in reduced-power modes, sacrificing power output for noise reduction. Therefore, when these conditions are met, turbine noise emissions directly and negatively impact its economic viability.

[0004] Because this problem has been known for several years, various methods have been proposed to reduce flow-induced edge noise in rotor blades. These methods include the shape and design of airfoils. In this context, the shape and design of the trailing edge of the rotor blades are particularly important. Aerodynamic accessories can be added to or included in the rotor blades to minimize flow-induced edge noise. Well-known accessories for noise reduction are serrations, such as serrated panels, which are mounted close to the trailing edge to the pressure or suction side of the rotor blade. However, the flow-induced edge noise that still exists and is generated can still be quite significant.

[0005] Recently, technology development projects have been initiated to develop active noise cancellation systems for trailing-edge noise in wind turbines. Patent application EP 3249216 A1 discloses a system that uses measured unstable surface pressure on the wind turbine blades to feed a noise cancellation controller, which generates a reverse acoustic signal to eliminate trailing-edge noise in the far field. However, active solutions are still in the early stages of development. Summary of the Invention

[0006] The object of this invention is to improve known systems, devices, and methods to facilitate improvements in noise reduction involving rotor blades (with active devices).

[0007] This objective is achieved by the rotor blades of the present invention, the method of the present invention, and the wind turbine of the present invention.

[0008] The rotor blade according to the invention has a leading edge and a trailing edge, and is designed and configured to be exposed to fluid flowing substantially from the leading edge to the trailing edge of the rotor blade. For example, the rotor blade is a rotor blade of a wind turbine. The rotor blade includes at least two sensors designed to detect the flow characteristics of the fluid and provide corresponding sensor signals, and the rotor blade further includes at least two actuators for generating anti-noise signals based on the sensor signals. The sensors and actuators are arranged on the surface of the rotor blade, with the sensors arranged along the spanwise direction and the actuators arranged along the chord direction. Furthermore, the actuators are arranged and prepared such that flow-induced edge noise of the rotor blade generated by the fluid is at least partially eliminated by the anti-noise signals.

[0009] Rotor blades typically consist of a root (connected to the rotor's axis) and a tip. In operation, they move in a predetermined direction, where the edge pointing in the direction of movement is the leading edge, and the opposite edge is the trailing edge. Because rotor blades are formed to create a pressure difference between their two surfaces, they include a pressure side and a suction side. Rotor blades are characterized by their span and chord; the span is a straight line projecting away from the root along the direction of the tip, and the chord is perpendicular to the span orientation, pointing from the leading edge to the trailing edge.

[0010] The rotor blades include at least two sensors for detecting the flow characteristics of the fluid, preferably at least three, five, seven, or more sensors. The sensors generate sensor signals based on the detected flow characteristics. These sensor signals are preferably pressure values ​​or pressure signals; however, they may (or alternatively) contain information about the direction and / or velocity of the flow.

[0011] The arrangement of sensors (and actuators) can be referred to as groups. Preferably, each group of sensors corresponds to the chordal distribution of the actuator (which is also a member of the group). Preferably, groups of spanwise sensors with a length of approximately 0.5 m to 2 m are arranged, each group corresponding to the chordal distribution of the actuator to eliminate noise emission from said section. Thus, preferably, a group of sensors covers at least 0.3 m, preferably at least 1 m, and particularly preferably at least 2 m of the rotor blade's span. Several sections of several groups may overlap; however, it is preferred that each group covers a separate section, wherein said sections do not overlap.

[0012] It should be noted that noise reduction or elimination is achieved through noise immunity. Since flow-induced edge noise is typically a broadband noise source caused by turbulence, it is random. Therefore, sound pressure fluctuations are uncertain, meaning that even with known statistical properties, they cannot be predicted temporally based on current or earlier acoustic signals. Noise can be predicted very accurately by means of the spanwise arrangement of sensors.

[0013] The rotor blades include at least two actuators, preferably at least three, five, seven, or more. The actuators on the rotor blades are designed to generate noise-resistant signals. For each set of sensors, there may be one actuator or two or more actuators. While it is preferable to use signals from two or more sensors to generate the noise-resistant signal for a single actuator, it is also possible to use the signal from a single sensor to generate the output signal for a single actuator (e.g., each sensor connected to one actuator). Interleaving the use of sensor signals is also preferred, as the signal from at least one sensor can be used to generate the output signal for two or more actuators, wherein the output signal of at least one of these actuators is generated by using the signal from another sensor.

[0014] The sensors and actuators are arranged on the surface of the rotor blades. This means that the sensors and actuators are integrated or added to the surface of the rotor blades in some way. To prevent adverse aerodynamic effects, one option is to immerse and insert the sensors and actuators into the housing or surface portion of the rotor blades, so that they are in contact with the surrounding air, but do not protrude and generate additional turbulence on the surface of the rotor blades.

[0015] The sensors are arranged along the wingspan direction (i.e., along the wingspan direction, preferably along a line). The actuators are arranged along the chord direction (i.e., along the chord direction, preferably along a line). The wingspan distribution of the sensors associated with the actuator group aligned with the chord direction allows for the generation of noise-resistant signals based on noise radiated from the entire wingspan section of the rotor blade where the sensors are arranged. As described above, preferably, the sensors will be arranged in one or more groups along the wingspan (i.e., along a wingspan length of 1 m - 2 m), and a group of chord-direction actuators will likely be associated with a group of wingspan-direction sensors, wherein preferably, multiple groups of these groups will exist along the rotor blades (preferably on both sides of the blades). In particular, the control unit can be fed sensor signals and determine noise-resistant signals for (one group of) actuators.

[0016] The actuator must be arranged and prepared such that the edge noise of the rotor blades, induced by fluid flow, is at least partially eliminated by an anti-noise signal. Such preparation is generally known, for example, from the disclosure of the aforementioned patent application EP3249216 A1. However, this invention represents an improvement on the concept of active noise cancellation by means of a specific arrangement of the sensor and actuator. The actuator aligned with the sensor should emit an anti-noise signal representing the anti-noise of (and detection of) the total sound radiated from the spanwise segment where the sensor is arranged. In an ideal environment, a single chordal distribution of the sensor may be sufficient to eliminate noise emitted from any blade segment of arbitrary length, provided that an observer at the location where the noise is to be cancelled remains in the geometrically far field (i.e., at a distance greater than approximately 5 blade-segment lengths).

[0017] The chordal distribution of the actuators provides control over the directionality of the emitted noise cancellation signal. The phase interaction of the corresponding actuator outputs in the far field results in a non-uniform directionality, which may approximate the non-uniform directionality emitted by the trailing edge noise itself. This allows the system to achieve noise cancellation over a wide range of directions around the blade.

[0018] Sensor outputs from a set of spanwise directional sensors (e.g., unstable pressure sensors) are used to generate real-time predictions of noise emitted from the corresponding blade sections covered by the sensors. The predicted noise emission is based on a physical model that correlates the unstable surface pressure on the airfoil with the emitted acoustic noise. The relationship between the measured surface pressure and far-field noise can be further refined experimentally and may also depend on, for example, the presence of trailing-edge geometry or serrations. Since the emission from the blade section is a function of the observer's position relative to the blade section (i.e., emission directivity), the noise immunity signal transmitted to actuators (e.g., loudspeakers) distributed along the chord direction must also reflect this observer position dependence. To most effectively eliminate noise over a wide range of observer positions, the noise immunity generation algorithm should reflect the trailing-edge noise directivity and will likely be based on a control strategy that minimizes the total mean square noise level across the distribution of observer positions relative to the blade section.

[0019] As described above, according to the invention, each sensor may be aligned with a single actuator. However, it is particularly preferred that signals from at least two sensors (or three or more sensors) are used together to generate at least two spatial noise-resistant signals, which are then emitted by at least two actuators.

[0020] A method according to the invention for constructing rotor blades (according to the invention) includes the following steps:

[0021] - Provide rotor blades with leading and trailing edges, wherein the rotor blades are designed and configured to be exposed to fluid flowing substantially from the leading edge to the trailing edge;

[0022] - Provide at least two sensors designed to detect the flow characteristics of a fluid and provide corresponding sensor signals, and at least two actuators designed to generate noise-resistant signals based on the sensor signals;

[0023] - The sensor is arranged on the surface of the rotor blade along the spanwise direction, and the actuator is arranged on the surface of the rotor blade along the chord direction, wherein the actuator is arranged and prepared such that the edge noise of the rotor blade caused by the flow generated by the fluid is at least partially eliminated by the noise-resistant signal.

[0024] A wind turbine according to the invention comprises at least one rotor blade manufactured according to the invention or by means of the method according to the invention.

[0025] It should be noted that the term 'actuator' must be understood broadly, for example, as any device capable of converting an electrical or pressure signal into physical mechanical movement. Examples of such actuators are diaphragms, loudspeakers, or deformable surfaces of rotor blades. 'Actuator' can include any device suited and capable of generating a desired noise-resistant signal, which is then used to at least partially eliminate flow-induced edge noise.

[0026] Similarly, the term 'sensor' must be understood broadly as any device capable of detecting the flow characteristics of fluid passing through it. A sensor may, for example, include a diaphragm. It may also include some kind of microphone. In its simplest form, a sensor may simply be a small opening in a surface that senses the fluctuations in surface pressure caused by the fluid passing through the opening, such that this pressure then triggers and generates an anti-noise signal.

[0027] Particularly advantageous embodiments and features of the invention are given, as disclosed in the following description. Different features may be combined as appropriate to provide other embodiments not described herein.

[0028] According to the preferred rotor blades, the sensors are arranged along the wingspan line along the trailing edge of the rotor blades. As described above, the inventors have found that the wingspan distribution of the sensors (i.e., along the blade's wingspan) has the advantage that an actuator located at a single wingspan position can eliminate the total noise from the extended wingspan section (rather than the very narrow area characterized by a single sensor). Therefore, using more than one sensor signal to generate an anti-noise signal for an actuator, along with the wingspan arrangement of the sensors, is particularly preferred.

[0029] Depending on the preferred rotor blades, the sensor is located downstream of the actuator relative to the direction of fluid flow. The actuator uses signals from at least one of these sensors (in particular all of them) to generate its noise-resistant signal.

[0030] Depending on the preferred rotor blade, the sensor includes a microphone (e.g., a surface microphone), and the actuator includes a speaker and is arranged and prepared to emit an acoustic signal using the speaker. Microphones and speakers are well-known and readily available inexpensive devices that can be integrated or added to rotor blades in virtually any size in a simple and inexpensive manner without affecting the aerodynamic flow around the blades.

[0031] According to a preferred rotor blade, the sensor includes a surface pressure transducer, and the actuator includes a diaphragm and is arranged and prepared to induce at least partial elimination of unstable surface pressure with said diaphragm. Suitable pressure transducers are well known and well-proven, and can be added to or implemented as well as included in the rotor blade without significant cost or modification to said rotor blade.

[0032] Depending on the preferred rotor blades, at least one additional actuator is arranged relative to the other actuators along the spanwise direction. For example, there is an actuator along the chord line and an actuator (or more actuators along a second chord line) adjacent to these actuators, preferably adjacent to one of the other actuators. Such an additional actuator may even touch one of the other actuators.

[0033] Depending on the preferred rotor blades, the actuator's noise immunity signal is based on sensor signals from at least two sensors, preferably from three or more sensors.

[0034] The preferred rotor blade further includes a control unit for constructing a noise-resistant signal, which is arranged such that the actuator is connected to at least one of the sensors via the control unit.

[0035] Depending on the preferred rotor blades, multiple sensors (in a set) are located on the suction side, and multiple sensors are located on the pressure side. The actuator using the sensor signals from this set of sensors is preferably located on both the pressure and suction sides; however, the actuator may also be arranged on only one of these sides.

[0036] Depending on the preferred rotor blades, the actuator and / or control unit are connected to at least one of the sensors via a connecting device, wherein the connecting device is preferably designed to guide electrical or pressure signals. If the connecting device is designed to guide electrical signals, it is preferably an electrical wire. If the connecting device is designed to guide pressure, it is preferably designed as a flexible tube or channel.

[0037] The preferred rotor blade includes at least three sensors arranged in a non-uniform manner, preferably with quadratic, exponential, chaotic or logarithmic intervals, or arranged in an alternating nonlinear manner such that there are alternating long and short intervals along the arrangement of the sensors, wherein the intervals are non-periodic.

[0038] As described above, the at least three sensors are preferably arranged with a non-uniform spacing (preferably arranged at least laterally on the surface). This means that although the sensors can all be arranged flush with or similarly protruding from the surface of the rotor blades, the lateral distance between adjacent sensors must be non-uniform. The sensors can be arranged haphazardly in an area, however, preferably along one or more lines (where the spacing between adjacent sensors is non-uniform). Particularly preferably, all distances between adjacent sensors have different values, such that even a periodic arrangement is not present.

[0039] In a preferred embodiment of the invention, the rotor blade includes a portion having an airfoil shape, the airfoil comprising a pressure side and a suction side, each defined by the trailing and leading edges of the rotor blade. In other words, the preferred rotor blade is a lift-generating rotor blade that at least partially has an airfoil shape. The airfoil is characterized by including a pressure side and a suction side, and being capable of generating lift when exposed to fluid flowing substantially from the leading edge to the trailing edge of the rotor blade. As is well known to those skilled in the art, the outer surface of such an airfoil-shaped rotor blade is characterized by a portion called the pressure side, defined on one side by the trailing edge and on the other by the leading edge, and the remainder of the surface generally referred to as the suction side of the rotor blade.

[0040] The rotor blades are preferably designed for use in wind turbines. However, the concept of the invention is not limited to edge noise caused by flow in the rotor blades of wind turbines. It can also be used to reduce edge noise caused by flow from, for example, aircraft wings, helicopter blades, fans, etc.

[0041] The special arrangement of sensors and actuators according to the invention offers advantages that result in more efficient rotor blade performance while requiring fewer actuators. Although a sensor grid distributed above the suction side of the blade can provide the same information as the invention, the information from sensors further upstream of the trailing edge is practically useless due to decorrelation of spatial turbulence conditions upstream of the trailing edge. The latter radiates acoustic energy due to its interaction with the edge. Therefore, the invention reduces the number of sensors, and thereby reduces the overall cost.

[0042] Furthermore, the chordal distribution of the actuators provides control over the directivity of the total secondary source (actuator array) along the pole direction (i.e., the plane perpendicular to the wingspan direction via the phase interaction of multiple actuators). Ideally, the secondary source will match the directivity of the primary source (the trailing edge noise of the blade) in the same way, allowing noise to be eliminated anywhere. The chordal distribution simply provides an efficient approximation of this situation, where the directivity is controlled along the pole direction, and the directivity is naturally dipole in the plane perpendicular to the chord.

[0043] An unlimited number of sensors and / or actuators can be arranged. Attached Figure Description

[0044] Other objects and features of the invention will become apparent from the following detailed description taken in conjunction with the accompanying drawings. However, it should be understood that the drawings are for illustrative purposes only and are not intended to limit the scope of the invention.

[0045] Figure 1 A typical rotor blade is shown.

[0046] Figure 2 The outline of the rotor blades at a certain spanwise position is shown.

[0047] Figure 3 illustrates an embodiment of the prior art, which includes a sensor and an actuator that are directly connected via a connection device.

[0048] Figure 4 An embodiment of the invention is shown, which includes a plurality of sensors and actuators directly connected via a connection device.

[0049] Figure 5 A block diagram illustrating the processing flow of a preferred method according to the present invention is shown.

[0050] Figure 6 An embodiment of a wind turbine according to the present invention is shown.

[0051] Figure 7 The theoretical directional pattern of trailing edge noise is shown.

[0052] In the accompanying drawings, similar reference numerals always refer to similar objects. The objects in the accompanying drawings are not necessarily drawn to scale. Detailed Implementation

[0053] Figure 1Rotor blade 2 is shown. Rotor blade 2 includes a root 21, a tip 22, a leading edge 23, and a trailing edge 24. The figure illustrates a top or plan view reaching the rotor blade 2, i.e., the pressure side of the rotor blade. Rotor blade 2 is characterized by a span 25, which is a straight line projecting away from the root 21. In the rotor blade 2 of the wind turbine 1 (see, for example...) Figure 6 In the case of ), the rotor blade 2 can pitch around the pitch axis.

[0054] Furthermore, multiple chords 26 can be assigned to the rotor blade 2. Each chord 26 is oriented perpendicular to the wingspan 25. Therefore, for each spanwise position starting at the root 21 along the direction of the tip 22, a chord 26 can be defined. The largest (i.e., the one with the largest length or extension) chord 26 is called the maximum chord 261. The region where the maximum chord 261 is located is called the shoulder 262 of the rotor blade 2.

[0055] If rotor blade 2 moves in a fluid such as air, the unstable surface pressure mode that generates sound at the edge can be considered to convect in a constant manner with the flow along the chord 26 of rotor blade 2. It should be noted that, in reality, this constant convection occurs to a certain extent. This means that minimal change in the unstable surface pressure mode is possible. This phenomenon is referred to in the literature as the 'frozen turbulence' hypothesis. In this invention, this fact is used to detect the unstable surface pressure upstream of the edge, allowing noise to be constructed and emitted in opposite phases at the moment the turbulent eddies, which are the cause of the unstable surface pressure mode and noise generation, pass through the edge, thus eliminating the noise-canceling signal.

[0056] Figure 2 A schematic diagram of the airfoil of rotor blade 2 is shown. This airfoil, or profile, is cut perpendicular to the span 25 of rotor blade 2. In other words, this profile is a cross-sectional view of rotor blade 2 at a specific radial or spanwise position. The leading edge 23 can be seen and described as a relatively rounded edge, thereby the trailing edge 24 is designed to be relatively sharp. The straight line connecting the leading edge 23 and the trailing edge 24 is called the chord 26.

[0057] It should be noted that the entire region extending from the leading edge 23 to the chord 26, which is 10 percent of the chord length measured from the leading edge 23, is called the leading edge segment 231. Similarly, the region within 10 percent of the chord length from the trailing edge 24 is called the trailing edge segment 241.

[0058] It should be noted that in this schematic diagram, the maximum thickness of the airfoil, defined as the distance between the pressure side 28 and the suction side 27, is relatively large. At least in modern rotor blades 2 of wind turbines 1, this thickness often decreases significantly towards the tip 22 of the rotor blade.

[0059] Figure 3 shows a trailing edge section 241 according to the prior art, which includes a sensor 31 positioned on the suction side 27 of the rotor blade 2 and directly connected to an actuator 32. The sensor 31 is positioned upstream of the actuator 32, which is arranged and positioned on the suction side 27 of the rotor blade 2.

[0060] Sensor 31 is connected to actuator 32 via connection device 34. Actuator 32 is configured to generate an anti-noise signal 36 based on the input received by sensor 31. The anti-noise signal 36 emitted by actuator 32 is indicated by a dashed arrow.

[0061] The noise suppression signal 36 is intentionally chosen to destructively interfere with the noise 35 generated and emitted at the trailing edge 24 of the rotor blade 2. Note that here, the two main directions of the noise 35 are visualized by two arrows, one protruding away from the trailing edge 24 towards the suction side 27, and the other protruding away from the trailing edge 24 towards the pressure side 28. In the exemplary embodiment of the figures, the noise suppression signal 36 primarily eliminates or minimizes the noise 35 emitted and generated at the trailing edge 24 towards the suction side 27. If desired, a pressure-side actuator 32 (not shown) can be added to also eliminate the noise 35 emitted towards the pressure side 28. Also note the turbulent boundary layers represented by the suction-side vortex 421 and the pressure-side vortex 422. The overall flow direction of the fluid is indicated by reference numeral 41.

[0062] Figure 4 An embodiment of the invention is shown, comprising four sensors 31 and three actuators 32, which are directly connected via a connecting device 34. The sensors 31 and actuators 32 are arranged on the surface of a rotor blade 2, with the sensors 31 arranged along the trailing edge in the spanwise direction and the actuators 32 arranged in the chord direction. The rotor blade 2 has a leading edge 23 and a trailing edge 24 and is designed and configured to be exposed to fluid flowing substantially from the leading edge 23 to the trailing edge 24.

[0063] Here, the rotor blade 2 includes three actuators 32 for generating an anti-noise signal 36 (see, for example, FIG. 3) based on sensor signals from all four sensors 31. The actuators 32 are connected to the sensors 31 via a connection device 34. Optionally, a control unit 33 (dashed line) may be present between the sensors 31 and the actuators 32 to generate the anti-noise signal from the sensor signals. The actuators 32 are arranged and prepared such that the flow-induced edge noise 35 of the rotor blade 2 generated by the fluid is at least partially eliminated by the anti-noise signal 36. The chordal distribution of the actuators 32 provides control over the directionality of the emitted anti-noise signal; the phase interaction of the corresponding actuator outputs in the far field results in a non-uniform directionality, which may approximately match the non-uniform directionality emitted by the trailing edge noise itself. This allows the system to achieve noise cancellation in a wide range of directions around the blade. It should be noted that although the turbine's noise emission exhibits some asymmetry, noise cancellation should be likely to occur in both directions. Therefore, preferably, the arrangement shown should be applied to the suction side 27 and the pressure side 28 of the rotor blade 2.

[0064] The dashed lines show the positions of the two additional actuators 32a as they are displaced along the wingspan to the positions of the two other actuators 32.

[0065] Figure 5 A block diagram illustrating the processing flow of a preferred method according to the present invention is shown.

[0066] In step I, rotor blades 2 are provided (see example...) Figure 1 The system includes three sensors 31 and two actuators 32. As described above, the sensors 31 are designed to detect the flow characteristics of the fluid and provide corresponding sensor signals, and the two actuators 32 are designed to generate noise-resistant signals 36 based on the sensor signals.

[0067] In step II, sensor 31 is arranged along the spanwise direction on the surface of the rotor blade 2 at the trailing edge 24 (see arrow), and actuator 32 is arranged along the chordwise direction on the surface of the rotor blade 2 (see arrow), wherein actuator 32 is arranged and prepared such that the edge noise 35 of the rotor blade 2 caused by the flow generated by the fluid is at least partially eliminated by the noise reduction signal 36.

[0068] Figure 6 A wind turbine 1 according to the present invention is illustrated, having three rotor blades 2, the rotor blades 2 having a sensor and actuator configuration according to an embodiment of the present invention (see, for example...). Figure 4 Rotor blade 2 is connected to hub 5 of wind turbine 1. Hub 5 is connected to nacelle 3 on top of wind turbine tower 4.

[0069] Figure 7The theoretical directional pattern of trailing-edge noise is shown, with fluid flowing in the direction of the arrow ("inflow"). The inflow occurs along the chord direction of the rotor blades. The cardioid (heart-shaped) curve plots the amplitude of the noise along the chord direction, with the arrow "amplitude" indicating an example of the noise amplitude at an angle of approximately 40°. The chord direction distribution simply provides an efficient approximation of this case, where the directionality is controlled along the pole direction, and the directionality is naturally dipole in the plane perpendicular to the chord (along the Y and Z directions).

[0070] While the invention has been disclosed in the form of preferred embodiments and variations thereof, it will be understood that many additional modifications and changes can be made thereto without departing from the scope of the invention. For clarity, it should be understood that the use of “a” or “an” throughout this application does not exclude a plurality, and “comprising” does not exclude other steps or elements. References to a “unit” or a “device” do not exclude the use of more than one unit or device.

Claims

1. A rotor blade (2) having a leading edge (23) and a trailing edge (24), wherein - The rotor blades (2) are designed and configured to be exposed to fluid flowing from the leading edge (23) to the trailing edge (24). - The rotor blade (2) includes at least two sensors (31) designed to detect the flow characteristics of the fluid and provide corresponding sensor signals, and -The rotor blade (2) further includes at least two actuators (32) that generate an anti-noise signal (36) based on sensor signals. - The sensor (31) is arranged along the spanwise direction on the surface of the rotor blade (2), and the actuator (32) is arranged along the chord direction on the surface of the rotor blade (2), wherein, The sensors (31) are arranged in groups corresponding to the chordal direction of the actuators (32), and - The actuator (32) is arranged and prepared such that the edge noise (35) of the rotor blades (2) caused by the flow generated by the fluid is at least partially eliminated by the anti-noise signal (36).

2. The rotor blade according to claim 1, wherein, The sensor (31) is arranged along the wingspan along the trailing edge.

3. The rotor blade according to claim 1, wherein, The sensor (31) is located downstream of the actuator (32) relative to the flow direction of the fluid.

4. The rotor blade according to any one of claims 1 to 3, wherein, The sensor (31) includes a microphone, and the actuator (32) includes a speaker and is arranged and prepared to emit sound signals using the speaker. and / or The sensor (31) includes a surface pressure transducer, and the actuator (32) includes a diaphragm and is arranged and prepared to induce at least partial elimination of unstable surface pressure with the diaphragm.

5. The rotor blade according to any one of claims 1 to 3, wherein, The sensors in the group are arranged to cover at least 0.3m of the rotor blades' wingspan.

6. The rotor blade according to any one of claims 1 to 3, wherein, The sensors in the group are arranged to cover at least 1 m of the rotor blades' wingspan.

7. The rotor blade according to any one of claims 1 to 3, wherein, Two or more sets of sensors (31) and actuators (32) are arranged on the rotor blades (2).

8. The rotor blade according to any one of claims 1 to 3, wherein, At least one additional actuator (32a) is arranged relative to the other actuators (32) along the wingspan.

9. The rotor blade according to any one of claims 1 to 3, wherein, At least one additional actuator (32a) is arranged adjacent to one of the other actuators (32) along the wingspan.

10. The rotor blade according to any one of claims 1 to 3, wherein, The noise-resistant signal (36) of the actuator (32) is based on sensor signals from at least two sensors (31).

11. The rotor blade according to any one of claims 1 to 3, wherein, The noise-resistant signal (36) of the actuator (32) is based on sensor signals from three or more sensors (31).

12. The rotor blade according to any one of claims 1 to 3, further comprising a control unit (33) for constructing the noise-resistant signal (36), which is arranged such that the actuator (32) is connected to at least one of the sensors (31) via the control unit (33).

13. The rotor blade according to any one of claims 1 to 3, wherein, Multiple sensors (31) are located on the suction side (27) and multiple sensors (31) are located on the pressure side (28), and the actuator (32) using the sensor signals of these sensors (31) is located on the pressure side (28) and / or the suction side (27).

14. The rotor blade according to any one of claims 1 to 3, wherein, The actuator (32) and / or control unit (33) are connected to at least one of the sensors (31) via a connection device (34).

15. The rotor blade according to claim 14, wherein, The connection device is designed to guide electrical or pressure signals.

16. The rotor blade according to claim 14, wherein, The connecting device (34) is an electrical wire or is designed as a flexible tube or channel.

17. The rotor blade according to any one of claims 1 to 3, comprising at least three sensors (31) arranged in a non-uniform manner, or arranged in an alternating non-linear manner such that alternating long and short spacing exists along the arrangement of the sensors (31), wherein, The spacing is non-periodic.

18. The rotor blade according to any one of claims 1 to 3, comprising at least three sensors (31) arranged at quadratic, exponential, chaotic, or logarithmic intervals, or arranged in an alternating nonlinear manner such that alternating long and short intervals exist along the arrangement of the sensors (31), wherein, The spacing is non-periodic.

19. The rotor blade according to any one of claims 1 to 3, comprising a portion having the shape of an airfoil.

20. The rotor blade according to any one of claims 1 to 3, wherein, The rotor blades (2) are designed for use in a wind turbine (1).

21. A method for constructing rotor blades (2), comprising the following steps: - A rotor blade (2) is provided with a leading edge (23) and a trailing edge (24), wherein the rotor blade (2) is designed and configured to be exposed to fluid flowing from the leading edge (23) to the trailing edge (24). - Provides at least two sensors (31) designed to detect the flow characteristics of the fluid and provide corresponding sensor signals, and at least two actuators (32) designed to generate noise-resistant signals (36) based on the sensor signals. - The sensor (31) is arranged along the spanwise direction on the surface of the rotor blade (2), and - The actuator (32) is arranged along the chord direction on the surface of the rotor blade (2), wherein the sensors (31) are arranged in groups corresponding to the distribution of the actuator (32) along the chord direction, and wherein the actuator (32) is arranged and prepared such that the edge noise (35) of the rotor blade (2) caused by the flow generated by the fluid is at least partially eliminated by the noise-reducing signal (36).

22. A wind turbine (1) comprising at least one rotor blade (2) according to any one of claims 1 to 20 or at least one by means of... Rotor blade (2) manufactured according to the method of claim 21.

Images