Patent Application
20240018941
The present invention relates to a wind turbine rotor blade and a wind turbine.
Since rotor blades are exposed to all weather conditions unprotected, the rotor blades can become iced at specific temperatures. A rotor blade heater can be used to prevent this. Either a heater can here be provided outside on the rotor blade, or heated air can be made available inside of the rotor blade. For example, this can take place by means of a heating register, which generates hot air that is then blown into the interior of the rotor blade.
WO 2017/021350 A1 shows a wind turbine rotor blade with a rotor blade root area and a rotor blade tip area, as well as a rotor blade heater. At least one web is further provided along a longitudinal axis of the rotor blade. A deflection unit in the form of a bar drop can be provided on the web, so as to reduce air turbulence in the deflection process.
WO 2018/211055 shows a wind turbine rotor blade with a rotor blade heater. The rotor blade has a web and a deflection unit in the area of the rotor blade tip for deflecting heated air.
On the European patent application from which priority is claimed the European Patent Office searched the following documents: EP 3 048 296 A1 and EP 3 048 297 A1.
Provided is a wind turbine rotor blade that enables an improved heating of the rotor blade.
Provided is a wind turbine rotor blade with a rotor blade root, a rotor blade tip, a pressure side, a suction side, a leading edge, and a trailing edge. The rotor blade has a longitudinal direction. A rotor blade heater is used to generate hot air, which is then blown into the interior of the rotor blade. At least one passively controllable air control element is provided in the air guide inside of the rotor blade. The air control element makes it possible to influence or control the air flow in the air guide inside of the rotor blade. As a result, for example, the air masses with varying temperatures (hot air in the middle of the air flow and colder air toward the rotor blade exterior) mix together better inside of the rotor blade.
The passively controllable air control element optionally has a temperature-dependent section, which changes its shape depending on the temperature. Therefore, the air control element reacts automatically to a change in temperature, which leads to a change in the air guide. The temperature-dependent change can exert an influence on the air flow so as to increase efficiency. At least one web is optionally provided between the pressure side and the section side along the longitudinal direction of the rotor blade. The air heated by the rotor blade heater can be blown along the web in the direction of the rotor blade tip, where it is deflected, so that the heated air on the other side of the web can flow back from the rotor blade tip area to the rotor blade root area. At least one passively controllable air control element can be provided along a web to influence the air flow.
The passively controllable air control element has no active control elements, but rather only passively controllable elements. As a result, there is no active intervention in the air control elements. The passively controllable element can permit a temperature-dependent, passive control. To this end, the air control element can at least partially allow a temperature-dependent deformation.
According to an aspect, the passively controllable air control element can have a bimaterial section with a first and a second material section. The material of the first material section has a different thermal expansion coefficient than the material of the second material section. Given a change in temperature, it can thus happen that the first and the second material section expand differently, thereby resulting in a deformation of the bimaterial section.
The bimaterial section is preferably provided as a bimetal section with a first and second metal section with different heat expansion coefficients. As the temperature increases, the first and second metal sections, which are coupled with each other, expand differently, causing the bimetal section to bend in the direction of the metal section with the lower expansion coefficient. This change in shape exerts an influence on the air flow of the heated air inside of the rotor blade.
The passively controllable air control element can be designed as a passively controlled, static mixer. The mixer has a bimaterial section with a first and second material, which are coupled together, and have different heat expansion coefficients. An air conducting element is further coupled to the bimaterial section. For example, deforming the bimaterial section leads to a change in the angle of the air guide element. As a consequence, an air flow in the air guide of the rotor blade heater inside of the rotor blade can be changed by the passively controlled, static mixer, for example. The bimaterial section deforms according to the temperature, thereby changing the position of the air conducting unit, which in turn produces a change in the air flow in the air guide.
The passively controlled air control element can be designed as a passively controlled swirl generator. The swirl generator can have a bimaterial section with a first and second material with different heat expansion coefficients. A heating or cooling of the bimaterial section is accompanied by a deformation of the bimaterial section. As a consequence, a change in the shape of the swirl generator takes place, thereby changing the air flow in the air guide of the rotor blade heater inside of the rotor blade. This makes it possible to achieve a passively controlled change in the air flow inside of the air guide of the rotor blade.
The passively controllable air control element can have an element that has a temperature-dependent change in length. This element can be coupled with a baffle plate, so that an angle of the baffle plate changes depending on the temperature, for example. As a result, the air flow inside of the air guide can be deflected, so that a swirling of the different temperature can take place. For example, the angle of the baffle plate can be enlarged with increasing temperature.
The passively controllable air flow elements can also be retrofitted in existing rotor blades.
The passively controlled air control elements can optionally be used to locally improve the rotor blade heater by locally influencing the air flow of the rotor blade heater.
The passively controllable air control element has at least a first and second operating position, wherein the air control element is active in the first operating position, and not active in the second operating position. Alternatively thereto, the air control element can be not active in the first operating position, and active in the second operating position. The transition from the first into the second operating position or from the second into the first operating position takes places depending on the temperature. In particular, a transition between the first and second operating positions takes place based upon a nonlinear expansion in the length of a bimaterial element, which has a first and a second material section with different heat expansion coefficients.
The passively controlled air control elements can be active (Vortex Generators VG, static mixer, flap (open)) in the initial position, and inactive (Vortex Generator VG inactive, static mixer inactive, flap (closed)) in the final position or vice versa. This can be achieved by the bimaterial element via targeted positioning or preloading.
The passively controllable air control element can be arranged on an inner wall of the rotor blade or on a web inside of the rotor blade. Alternatively thereto, the passively controllable air control element can also be fastened to other components in the interior of the rotor blade. In particular, an end of the passive air control element can here be fastened to the web or the inner wall, so that the other end protrudes into the inner volume of the rotor blade, and deforms depending on the temperature.
The passively controllable air control element with the temperature-dependent deformation can be configured as a swirl generator, static mixer and/or deflection bucket. The temperature-dependent variability (for example through the use of two bimaterial elements) can provide a passively controllable air control element that only acts on the air flow when needed. This is advantageous, since the passively controllable air control elements only act on the air flow if this is actually needed. For example, this makes it possible to avoid a permanent pressure loss caused by the passively controllable air control elements acting on the air flow of the rotor blade heater.
In particular if the passively controllable air control elements do not lead to a change in the air flow of the rotor blade heater in their normal operating mode, this will also not result in an impaired air flow in the normal state.
The passively controllable air control elements placed along the rotor blade can exert a local influence on the air flow of the rotor blade heater. This enables an improved local heating of specific sections of the rotor blade by the passively controllable air flow elements, so as to prevent or reduce ice buildup.
This allows for the possibility of not heating all areas of the rotor blade, but rather of achieving a local change in the temperature distribution.
Additional embodiments of the invention are the subject of the subclaims.
Advantages and exemplary embodiments of the invention will be explained in more detail below with reference to the drawing:
At least one web 410, 411, 412 extends along a longitudinal direction L of the rotor blade 200 inside of the rotor blade, and is part of the air guide 400 or already present for other reasons, with the air guide 400 having only a secondary function. More than one web can optionally be provided.
The air heated by the rotor blade heater 300 can be guided along the web 411 as part of the air guide 400 in the direction of the rotor blade tip 220, and then be deflected in the area of the rotor blade tip 220. To this end, a deflection section 402 can be present in the area of the rotor blade tip 220. The rotor blade tip 220 can optionally be at least partially hollow in design, so that a portion of the heated air can flow through the rotor blade tip 220, in order to also deice the rotor blade tip 220.
The heated air can be generated by means of the rotor blade heater 300 either in the rotor blade root area, by virtue of a heating unit 310 heating the air, or the heated air is supplied to the rotor blade 200 in the area of the rotor blade root 210.
At least one passively controllable air control element 800 can be provided along the length L of the rotor blade 200 in the air guide 400. The passively controllable air control element 800 is used to control or influence the air flow of the rotor blade heater inside of the rotor blade 200, e.g., via a temperature-dependent change in shape.
According to an aspect of the present invention, the passively controllable air control element 800 can be provided at different locations along the length L of the rotor blade 200 and in the interior of the rotor blade 200, for example between a web 411 and the rotor blade wall 202, or between a web 410 and a rotor blade trailing edge 430.
According to an aspect of the present invention, the passively controllable air control element 800 is used to (locally) influence an air flow inside of the air duct of the rotor blade, e.g., via a temperature-dependent change in shape.
According to an aspect of the present invention, the passively controlled air control element can significantly improve the air flow in the air guide for the rotor blade heater as a result of an elevated heat exchange on the surface to be heated (rotor blade wall) to be heated.
According to an aspect of the present invention, already installed rotor blades can be retrofitted with passively controlled air control elements, so as to raise the efficiency of the rotor blade heater.
In particular, the passively controlled air control elements can be used in rotor blades of a wind turbine that have a large length and a smaller inner cross section.
According to an aspect of the present invention, using passively controlled air control elements makes it possible to significantly improve a temperature of the air flow on the rotor blade shell. While the temperature of the air flow on the shell can already drop to 50° C. in prior art, the aerodynamic mixers can be used to increase the temperature of the air flow on the inner wall significantly, in particular to 70-80° C.
An improved heat transfer from the heated air to the material of the shell of the rotor blade can thus be achieved without the pressure losses being raised significantly in the process.
A thermal exchange cooler can thus improve a flow near the wall with a warm flow remote from the wall, without higher pressure losses resulting at the same time.
The passively controllable air control elements can be used here to activate (i.e., deform, for example) the elements if they are needed.
The passively controllable air control element 800 can have at least one first and second operating position. As shown on
As exemplarily shown on
On
The passively controlled air control elements can be active or passive in the initial position. A change can take place by influencing the bimaterial section (i.e., depending on temperature). If the air control elements are active, the Vortex Generators VG can then be active, the static mixer can be active, and the flap can be open. The passively controlled air control elements can be inactive in their final position, i.e., the Vortex Generators VG are inactive, the static mixers are inactive, and the flap can be closed. Alternatively thereto, the passively controlled air control elements could also be oppositely configured, i.e., the air control elements are inactive in the initial position and active in the final position.
The various embodiments described above can be combined to provide further embodiments. These and other changes can be made to the embodiments in light of the above-detailed description. In general, in the following claims, the terms used should not be construed to limit the claims to the specific embodiments disclosed in the specification and the claims, but should be construed to include all possible embodiments along with the full scope of equivalents to which such claims are entitled. Accordingly, the claims are not limited by the disclosure.
| Number | Date | Country | Kind |
|---|---|---|---|
| 22184291.7 | Jul 2022 | EP | regional |
