Patent Publication Number: US-2023151794-A1

Title: Wind turbine rotor blade

Description:
BACKGROUND 
     Technical Field 
     The present invention relates to a wind turbine rotor blade. 
     Description of the Related Art 
     Since the rotor blades of a wind turbine are exposed to all weather conditions without protection, the rotor blades can become iced over at certain temperatures. In order to prevent this, use can be made of a rotor blade heater. Either a heater can here be provided outside on the rotor blade, or heated air can be provided inside of the rotor blade. 
     A rotor blade heater is often used to prevent the rotor blades from icing over. Heater air is here typically introduced into the interior of the rotor blade in the area of the rotor blade root. The heated air in turn heats up the rotor blade shell, for example in the area of the rotor blade nose, so that a deicing of the rotor blade can be achieved. 
     WO 2017/021350 A1 shows a wind turbine rotor blade with a rotor blade root area and a rotor blade tip area and a rotor blade heater. Also provided is at least one web along a longitudinal direction of the rotor blade. A deflection unit for deflecting the air can be provided on the web. 
     WO 2018/211055 shows a rotor blade of a wind turbine, which has a web and a deflection unit on the rotor blade tip for deflecting heated air. 
     BRIEF SUMMARY 
     Provided is a wind turbine rotor blade with an improved rotor blade heater. 
     More particularly, provided is a wind turbine rotor blade with a rotor blade shell that envelops an internal volume, and has at least one vortex generator in the internal volume. By providing the vortex generators in the internal volume (e.g., on the interior side of the rotor blade shell), the air flow inside of the rotor blade shell can be improved, which leads to an improved heat transfer, and thus to an improved heating of the rotor blades. 
     According to an aspect of the invention, first vortex generators are provided on an interior side of the rotor blade shell. 
     According to an aspect of the present invention, the rotor blade has at least one web along a longitudinal direction of the rotor blade. At least one vortex generator can be arranged on the at least one web, or fastened with the web. 
     According to another aspect of the present invention, the rotor blade has at least one first and second web along a longitudinal direction of the rotor blade. Further provided is a first air channel between a front edge of the rotor blade and a first web, wherein at least one vortex generator is provided in the first air channel. 
     According to another aspect of the present invention, the rotor blade has a second air channel between a web and a rotor blade trailing edge. At least one vortex generator is provided at least partially in the second air channel along the longitudinal direction of the rotor blade. 
     According to another aspect of the present invention, the rotor blade has a least one vortex generator in a third air channel between the first and second webs. 
     According to another aspect of the present invention, the rotor blade has a rotor blade heating system in or on the root of the rotor blade. The rotor blade heating system generates warm air, which is conveyed into the internal volume of the rotor blade. 
     Provided is a wind turbine with at least one wind turbine rotor blade described above. 
     Mounting vortex generators on the interior side of the rotor blade shell and/or on the webs makes it possible to improve the heat transfer of the heated air to the rotor blade shell. Due to the geometry of the vortex generators, providing the vortex generators inside of the rotor blade does not result in a significant pressure loss. This is because the wall pressure loss depends primarily on the normal gradient of the velocity component along the primary direction of flow on the wall, and not on the gradient of the velocity component of the secondary flow. 
     Thus provided is a wind turbine rotor blade with a (two-part) blade shell, which envelops an internal volume. The rotor blade further has a rotor blade root and a rotor blade tip. At least one web can be provided at least sectionally between the two blade shells along a longitudinal direction of the rotor blade, so that the internal volume of the rotor blade is divided into at least two sections. The rotor blade further has a rotor blade heater, for example which is provided in the area of the rotor blade root, and conveys heated air into the internal volume of the rotor blade. To improve the effectiveness of the blade heater, at least one vortex generator is provided in the internal volume. The more uniform mixing of the flow caused by the vortex generators leads to an improved heat transfer to the rotor blade shells, so that an improved rotor blade heater can be achieved by providing the vortex generators. 
     According to an aspect of the present invention, a web is provided between the two blade shells (pressure side, suction side), so that an air channel comes about in the area of the rotor blade front edge, through and along which the air heated by the rotor blade heater can flow. At least one first vortex generator is provided in the area of the first channel, at least partially along a longitudinal axis of the rotor blade. 
     According to another aspect of the present invention, a second web is provided between the two rotor blade shells, so that a second channel arises in the area of the rotor blade trailing edge. An optional second vortex generator can be provided in this second channel. 
     According to an aspect of the present invention, a third channel can be provided at least partially between the first and second webs. Third vortex generators can optionally be provided in the third channel. 
     Providing the vortex generators in the internal volume of the rotor blade mixes the flow, which leads to a more uniform temperature distribution. This results in an increase in the heat transfer coefficient α. 
     In addition to the vortex generators, cross sectional constrictions can be provided inside of the rotor blades. A change in the blade internal flow takes place to improve a heat transfer of the heated air from the blade heater to the rotor blade shell. The cross sectional constrictions represent passive options for increasing the flow rate. 
     According to an aspect of the invention, the vortex generators and the cross sectional constrictions can be installed retroactively. 
     Additional configurations are the subject of the subclaims. 
    
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
       Advantages and exemplary embodiments of the invention will be explained in more detail below with reference to the drawing. 
         FIG.  1    shows a schematic view of a wind turbine according to the invention, 
         FIG.  2 A  show a schematic cross section and a schematic and  2 B longitudinal section of a rotor blade according to prior art, 
         FIG.  3 A  shows a schematic cross section of a rotor blade according to an aspect of the invention, and 
         FIG.  3 B  shows a schematic longitudinal section of a rotor blade according to  FIG.  3 A . 
     
    
    
     DETAILED DESCRIPTION 
       FIG.  1    shows a schematic view of a wind turbine according to the invention. The wind turbine  100  has a tower  102  and a nacelle  104  on the tower  102 . Provided on the nacelle  104  is an aerodynamic rotor  106  with three rotor blades  200  and a spinner  110 . During operation of the wind turbine, the wind imparts a rotational motion to the aerodynamic rotor  106 , which thus also turns a rotor or runner of a generator, which is directly or indirectly coupled with the aerodynamic rotor  106 . The electric generator is arranged in the nacelle  104 , and generates electric energy. The pitch angles of the rotor blades  200  can be changed by pitch motors on the rotor blade roots of the respective rotor blades  200 . 
     A rotor blade heater  500  can be provided in the area of a rotor blade root for purposes of rotor blade deicing. As an alternative thereto, the rotor blade heater  500  can be provided in an area of a rotor hub or on a rotor blade connector. The rotor blade heater  500  generates hot air, and then conducts it into the interior of the rotor blade to deice the rotor blade or prevent icing. 
       FIG.  2 A  shows a cross section of a rotor blade, and  FIG.  2 B  shows a longitudinal section of a rotor blade. The rotor blade  200  has two blade shells  210 ,  220  each having an interior side  211 ,  221 , which envelop an internal volume  203 . The rotor blade  200  further has a rotor blade leading edge  230  and a rotor blade trailing edge  240 . Webs  231 ,  232  can be provided between the blade shells  210 ,  220 , so that the internal volume  203  can be divided into various portions or channels  250 ,  260  and  270  (first channel  250  between the leading edge  230  and first web  231 , second channel  260  between the trailing edge  240  and second web  232 , and third channel  270  between the first and second webs  231 ,  232 ). For example, the web  231  can be longer than the web  232 . 
     Deflecting arcs  600  can optionally be provided at the free end of the webs. According to an aspect of the present invention, vortex generators can be provided in or on the deflecting arc. 
     At least one vortex generator  400  can be provided inside of the rotor blade, i.e., on the interior side of the rotor blade shells and/or on the webs  231 ,  232 . The vortex generator  400  can be placed in the entire internal volume of the rotor blade. For example, the vortex generators  400  can be placed in the first, second or third channel  250 ,  260 ,  270  on the interior sides  211 ,  221  of the rotor blade shells  210 ,  220  and/or on the webs  231 ,  232 . Providing the vortex generators  400  makes it possible to positively influence the air flow inside of the rotor blade. In particular, turbulences can be generated. As a result, a heat transfer of heated air generated by the rotor blade heater  500  to the rotor blade shells can be improved. 
     Several vortex generators  400  can be provided along the length of the rotor blade  200 . 
       FIGS.  3 A and  3 B  show a corresponding cross section of a rotor blade as well as a longitudinal section of the rotor blade according to an exemplary embodiment of the invention. While the channels  250 ,  260  and  270  with the vortex generators  400  are shown unchanged in the rotor blade according to  FIG.  2 A and  2 B , at least portions of the channels according to  FIGS.  3 A and  3 B  are provided with cross sectional constrictions  310  in the first channel  250 , with second cross sectional constrictions  320  in the second channel  260  and/or optionally with third cross sectional constrictions  330  in the third channel  270 . In addition to the vortex generators  400 , cross sectional constrictions  300  can thus be provided. 
       FIG.  3 B  shows the distribution of the cross sectional constrictions  310 ,  320 ,  330  along a longitudinal axis of the rotor blade. 
     Both the cross sections of the cross sectional constrictions and their distribution along the longitudinal axis of the rotor blade can differ from the cross sections and longitudinal distributions shown on  FIGS.  3 A and  3 B . 
     The cross sectional constrictions result in a higher flow rate of the air flowing through the rotor blade heater  500  into the interior (into the channels  250 ,  260 ,  270 ) of the rotor blade. 
     The cross sectional constrictions in combination with the vortex generators can help improve the rotor blade heater. 
     REFERENCE LIST 
       100  Wind turbine 
       102  Tower 
       104  Nacelle 
       106  Rotor 
       110  Spinner 
       200  Rotor blades 
       203  Internal volume 
       210  Blade shells 
       211  Blade shell interior side 
       220  Blade shells 
       221  Blade shell interior side 
       230  Rotor blade leading edge 
       231  Webs 
       232  Webs 
       240  Rotor blade trailing edge 
       250  Channels 
       260  Channels 
       270  Channels 
       300  Cross sectional constriction 
       310  Cross sectional constrictions 
       320  Cross sectional constrictions 
       330  Cross sectional constrictions 
       400  Vortex-generator 
       500  Rotor blade heater 
     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.