Pressure supply system for a pneumatically activatable aerodynamic device of a rotor blade of a wind turbine

Abstract

A wind turbine with a rotor blade, wherein the rotor blade includes a pneumatically activatable aerodynamic device and the wind turbine includes a pressure supply system for controlling the activatable aerodynamic device is provided. The pressure supply system includes a pressurized air supply system, a pressurized air transmission system with pressure lines for transmitting the supplied pressurized air from the pressurized air supply system to the aerodynamic device, and at least one pneumatic actuator for activating the aerodynamic device.

Claims

1. A wind turbine with a rotor blade, wherein the rotor blade comprises a pneumatically activatable aerodynamic device and the wind turbine comprises a pressure supply system for controlling the pneumatically activatable aerodynamic device, wherein the pressure supply system includes a pressurized air transmission system with pressure lines for transmitting pressurized air to the aerodynamic device, and at least one pneumatic actuator for activating the aerodynamic device, wherein the pneumatically activatable aerodynamic device comprises a cavity, wherein the actuator comprises an inflatable hose arranged in the cavity, wherein the inflatable hose contacts the pressure side of the rotor blade, and wherein the activatable aerodynamic device bends toward the pressure side of the rotor blade when the inflatable hose is inflated.

2. The wind turbine according to claim 1, wherein the wind turbine comprises a plurality of rotor blades and the pressure supply system provides pressurized air for all rotor blades.

3. The wind turbine according to claim 2, wherein a portion of the pressure supply system is located in the hub of the wind turbine.

4. The wind turbine according to claim 2, wherein the individual rotor blades can be controlled independently from each other by separately controlled individual valves which control the transmission of the pressurized air to the respective actuators of the individual rotor blades.

5. The wind turbine according to claim 1, wherein the wind turbine comprises a plurality of rotor blades and the wind turbine comprises individual pressure supply systems for each rotor blade.

6. The wind turbine according to claim 5, wherein each of the individual pressure supply systems is located in the root section of the corresponding rotor blade.

7. The wind turbine according to claim 1, wherein the pressure lines are aligned along at least a portion of a trailing edge of the rotor blade.

8. The wind turbine according to claim 1, wherein the pressure lines are aligned along at least a portion of a shear web of the rotor blade.

9. The wind turbine according to claim 1, wherein the wind turbine further comprises at least one pressure reservoir for storing pressurized air.

10. The wind turbine according to claim 9, wherein the pressure reservoir is located close to the at least one actuator, a distance which is less than ten per cent of the length of the rotor blade.

11. The wind turbine according to claim 1, wherein the wind turbine further comprises at least one vacuum reservoir for storing air with a pressure below atmospheric pressure.

12. The wind turbine according to claim 1, wherein the inflatable hose substantially fills the cavity of the pneumatically activatable aerodynamic device.

13. The wind turbine according to claim 1, wherein the actuator comprises an inlet port at which pressurized air flows into the actuator.

14. The wind turbine according to claim 1, wherein the actuator comprises an exhaust port at which pressurized air flows out of the actuator.

15. The wind turbine according to claim 1, wherein the pressure supply system further comprises a safety relief valve, which can be pneumatically activated, for enabling a discharge of the pressurized air from the actuator.

16. The wind turbine according to claim 1, wherein the pneumatically activatable aerodynamic device is a flap.

17. The wind turbine according to claim 16, wherein the flap attaches to the pressure side of the rotor blade.

18. The wind turbine according to claim 16, wherein the flap attaches to a trailing edge section of the rotor blade.

19. The wind turbine according to claim 16, wherein the flap attaches to both the pressure side of the rotor blade and a trailing edge section of the rotor blade.

Description

BRIEF DESCRIPTION

(1) Some of the embodiments will be described in detail, with references to the following Figures, wherein like designations denote like members, wherein:

(2) FIG. 1 shows a wind turbine;

(3) FIG. 2 shows a rotor blade of a wind turbine;

(4) FIG. 3 shows a wind turbine with a pressure supply system;

(5) FIG. 4 shows a pressure supply system with one common pressurized air supply system for all rotor blades;

(6) FIG. 5 shows individual pressurized air supply systems for each rotor blade;

(7) FIG. 6 shows the alignment of the pressure lines along the shear web and the provision of a pressure reservoir in a rotor blade;

(8) FIG. 7 shows the alignment of the pressure lines along the trailing edge of the rotor blade;

(9) FIG. 8 shows the provision of a pressure reservoir and a vacuum reservoir in the outboard part of the rotor blade;

(10) FIG. 9 shows a flap which is activatable by a hose; and

(11) FIG. 10 shows the same flap as in FIG. 9, but with an inflated hose.

DETAILED DESCRIPTION

(12) FIG. 1 shows a conventional wind turbine 10 for generating electricity. The wind turbine 10 comprises a tower 11 which is mounted on the ground 16 by one end. At the other end of the tower 11, there is mounted a nacelle 12. The nacelle 12 is usually mounted rotatable with regard to the tower 11, which is referred to as comprising a yaw axis substantially perpendicular to the ground 16. The nacelle 12 usually accommodates the generator of the wind turbine and the gear box (if the wind turbine is a geared wind turbine). Furthermore, the wind turbine 10 comprises a hub 13 which is rotatable about a substantially horizontal rotor axis 14 (including a small tilting angle of a few degrees). The hub 13 is often described as being a part of the rotor, wherein the rotor is capable to transfer the rotational energy to the generator.

(13) The hub 13 is the part at which the rotor blades 20 are mounted. The rotor blade 20 is usually mounted pivotable to the hub 13. In other words, the rotor blades 20 can be pitched about pitch axes 15, respectively. This improves the control of the wind turbine and in particular of the rotor blades by the possibility to modify the direction at which the wind is impinging on the rotor blades 20. Each rotor blade 20 is mounted to the hub 13 at its root section 21. The root section 21 is opposed to the tip section 22 of the rotor blade. Note that in the example as shown in FIG. 1, only two rotor blades 20 are depicted. However, most of the wind turbines nowadays comprise three rotor blades.

(14) FIG. 2 shows such a rotor blade 20 of a wind turbine comprising a root section 21 and a tip section 22. Both sections, the root section 21 and the tip section 22, comprise up to ten percent in the spanwise direction of the rotor blade. The radially outmost point of the rotor blade is the so-called tip 221 of the rotor blade 20. The rotor blade 20 furthermore comprises a trailing edge 231 and a leading edge 241. The leading edge 241 typically has a curved and rounded shape, while the trailing edge 231 typically has a sharp or blunt edge. The section around the leading edge 241 is referred to as the leading edge section 24; likewise, the section around the trailing edge 231 is referred to as the trailing edge section 23.

(15) The straight line between the trailing edge 23 and the leading edge 24 is called the chord line 27. The chord line 27 divides the airfoil into a pressure side 25 and a suction side 26. One of the airfoils is exemplarily shown in FIG. 2. It is to be understood that the rotor blade 20 comprises a plurality of airfoils—one next to the other—from the root section 21 to the tip section 22. These gradually changing airfoils cause the gradual change of the shape of the rotor blade. The airfoil has a lift generating shape in most of the sections of the rotor blade.

(16) FIG. 3 shows a wind turbine 10 with a pressure supply system according to embodiments of the invention. The wind turbine 10 is seen in a front view. Therefore, the nacelle 12 is hidden behind the hub 13 and is not visible in this perspective. Apart of that, the wind turbine 10 comprises three rotor blades 20, wherein each rotor blade 20 comprises an aerodynamic device 41 which is in the example of FIG. 3 configured as a trailing edge flap. The trailing edge flap is mounted at the trailing edge 231 of the rotor blades 20 and extends along the trailing edge 231 in the outboard part of the respective rotor blades.

(17) The pressure supply system comprises one common pressurized air supply system 31 which is located centrally in the hub 13. The pressurized air supply system 31 provides pressurized air to each of the three rotor blades. Therefore, a pressurized air transmission system 32 in the form of pressure lines extend from the pressurized air supply system 31 to the individual rotor blades. The transmission of pressurized air through the pressure lines is controllable via three individual valves, one for each rotor blade 20. After entering the rotor blades via the root section, the pressure lines run along the shear webs, which are not visible in FIG. 3, to the aerodynamic devices 41. Each pressurized air transmission system 32 enters a pneumatic actuator 33 at an inlet port and supplies the pneumatic actuator 33 with pressurized air.

(18) FIG. 4 illustrates again the variant of one common pressurized air supply system 31 being centrally located in the hub 13 of the wind turbine. In other words, there is one single input but multiple outputs of pressurized air.

(19) In contrast to the variant shown in FIG. 4, FIG. 5 shows an alternative realization, where there are multiple input sources and multiple output means. Concretely, one individual pressurized air supply system 31 is provided for each rotor blade and supplies one individual rotor blade with pressurized air. In the example shown in FIG. 5, the pressurized air supply systems 31 are located in the hub 13, but could alternatively also be located in the rotor blade, such as in the root section 21 of the rotor blades.

(20) FIG. 6 is a section cut at a rotor blade of a wind turbine. It may also be described as showing the pressure side shell of such a rotor blade, or, to be more precise, a part of it. The rotor blade comprises a shear web 42 which is located at approximately 40% chordal length as measured from the leading edge of the rotor blade. It can be seen that the pressurized air transmission system which brings and supplies air from the pressurized air supply system to the aerodynamic device runs along the shear web 42 until it reaches a pressure reservoir 43. The pressure reservoir is aligned and attached to the shear web 42. From the pressure reservoir 43 a pressurized air transmission system, concretely a pressure line, is running directly to the trailing edge of the rotor blade and exits the inner cavity of the rotor blade close to the trailing edge of the rotor blade. There, it is aligned at the pressure side 25 of the rotor blade until it reaches the pneumatic actuator 33.

(21) The pneumatic actuator 33 is able to move the aerodynamic device which is realized as a two-part flap 411 and the pneumatic actuator is able to move the flap 411 into the desired orientation. For example, a change of the orientation of the flap 411 downwards, i.e. further towards the pressure side 25 may considerably change the lift and the load of the rotor blade.

(22) As an alternative, FIG. 7 shows the alignment of the pressure lines not along the shear web but along the blunt and thick trailing edge 231 of the rotor blade. Here, the pressure lines 32 exit the blade already from the beginning on. Also note that in case of the embodiment as illustrated in FIG. 7, the pressurized air supply system 31 is located in the root section 21 of the rotor blade.

(23) FIG. 8 shows a complete view on a rotor blade 20 which comprises a pressure supply system. The pressure supply system comprises a pressurized air supply system 31 which is located in the root section 21 of the rotor blade 20. From the pressurized air supply system 31 a pressurized air transmission system in the form of pressure lines lead directly to a pressure reservoir 43. The pressure reservoir 43 is located in the outboard section of the rotor blade 20, namely close to the aerodynamic device 41 with the pneumatic actuator 33 which needs to be supplied with pressurized air. From the pressure reservoir 43, there reaches another pressure line to the pneumatic actuator 33. The pneumatic actuator 33 comprises an inlet port where the pressure lines reach the pneumatic actuator 33. Furthermore, the pneumatic actuator 33 also has an exhaust port which is connected with a vacuum reservoir 44. Also, the vacuum reservoir 44 is located in the outboard part of the rotor blade.

(24) Finally, FIGS. 9 and 10 show an example of a flap 411 which is an example of an aerodynamic device. The flap 411 is a trailing edge flap which is arranged at the trailing edge section 23 of the rotor blade. It comprises one part which is directly connected to the trailing edge section 23 of the rotor blade. The flap 411 also comprises another section by which the flap 411 is attached to the pressure side 25 of the rotor blade.

(25) The flap 411 comprises a cavity where a hose 331 is provided. The hose 331 almost fills the entire cavity. The hose 331 can be filled or emptied by air by means of a pressurized air transmission system which extends at the exterior of the rotor blade first and subsequently enters the cavity of the rotor blade. The actuator may also comprise an exhaust port, however this has been omitted in the cross-sectional view as shown in FIGS. 9 and 10 for sake of simplicity.

(26) The difference between the first configuration as illustrated in FIG. 9 and the second configuration as illustrated in FIG. 10 is the volume of the hose 331. In FIG. 9, the hose 331 is almost empty. In other words, it is deflated. No pressure is applied to the air which is present in the hose 331. Compared to that, in the second configuration as illustrated in FIG. 10, pressurized air has been pressed into the hose 331. Through careful design of the flap 411, the flap 411 changes its shape and its configuration when the hose 331 is inflated. In this case, the flap 411 bends downwards, i.e. towards the pressure side 25 of the rotor blade. This has the effect that the lift, and thus also the load of the rotor blade is changed. Note that FIGS. 9 and 10 only show one of many possible embodiments of such a pneumatic actuator.

(27) Although the invention has been illustrated and described in greater detail with reference to the preferred exemplary embodiment, the invention is not limited to the examples disclosed, and further variations can be inferred by a person skilled in the art, without departing from the scope of protection of the invention.

(28) For the sake of clarity, it is to 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.