Wind turbine

Abstract

The invention relates to a wind turbine (10) having a housing (12) and having an arrangement of two rotors (16, 17), which are mounted rotatably in opposite directions about vertical rotor axes (14, 15) in the housing (12) and each have a plurality of rotor blades (18), wherein the rotor axes (14, 15) lie in one plane (24), wherein the housing (12) in each case has a vertical air-guiding element (34, 35) in the outer regions (32, 33) on both sides of the arrangement of the rotors (16, 17), wherein the housing (12) has a vertical wind divider (40) in the central region (30) and on the approach flow side upstream of the arrangement of the rotors (16, 17), the vertical wind divider (40) being configured and arranged relative to the vertical rotor axes (14, 15) in such a way that the flow approaches the two rotors (16, 17) in the outer regions (32, 33), and the vertical wind divider (40) projecting on both sides into the outer regions (32, 33).

Description

[0001] wind turbine

[0002] Description

[0003] The invention relates to a wind turbine with a housing and an arrangement of two rotors, each having a plurality of rotor blades, mounted in the housing for counter-rotation about vertical rotor axes. These wind turbines are, in particular, so-called resistance rotors with vertical rotors. Their housing has a vertical air guide element on each side of the rotor arrangement on the upstream side and a vertical wind splitter centrally in front of the rotor arrangement.

[0004] Rotor arrangements of the aforementioned type are known, for example, from the documents DE 101 20 181 A1, DE 103 31 682 A1, DE 10 2016 105 409 B4, DE 20 2006 014 267 U1, or DE 199 57 141 B4. These developments concern, for example, a common shaft driven by both rotor shafts, or an optimization of the flow to the rotors by means of shape-changing air guide elements and wind dividers to increase efficiency, or the arrangement of interlaced rotors to reduce flow losses, or the geometry of a rear diffuser.

[0005] All of these documents address detailed solutions that are naturally intended to improve the efficiency of the rotor design in question. However, these measures are sometimes complex. Moving components also have the disadvantage of being more susceptible to wear and represent an additional potential source of unwanted vibrations in the turbine. The object of the present invention is to provide a wind turbine that achieves improved yield using simple, cost-effective, and robust means, while taking service life and price into account.

[0006] The object is achieved according to the invention by a wind turbine with a housing and with an arrangement of two rotors which are mounted in the housing so as to be rotatable in opposite directions about vertical rotor axes and each having a plurality of rotor blades, wherein the rotor axes lie in one plane, wherein the housing has an upstream side and a rear side, wherein regions which are located in a vertical projection onto the plane between the rotor axes are referred to as central and the remaining regions as outer regions, wherein the housing has a vertical air guide element on both sides of the arrangement of the rotors in the outer regions, wherein the housing has a vertical wind divider in the central region and on the upstream side in front of the arrangement of the rotors, wherein the vertical wind divider is designed and arranged relative to the vertical rotor axes,that both rotors are exposed to the airflow in the outer areas and the vertical wind divider extends into the outer areas on both sides.

[0007] The position and direction specifications "vertical," "horizontal," "top," "bottom," "upper," and "lower" refer herein, unless explicitly stated otherwise, to the direction of gravity. The position and direction specifications "in front," "front," "upstream," "behind," "rear," "backward," and the like refer herein, unless explicitly stated otherwise, to the wind direction during operation of the turbine, where "in front," "front," and "upstream" mean "facing the wind," and "behind," "rear," and "backward" mean "facing away from the wind."

[0008] The rotors rotate with the airflow in the outer section, and against the airflow in the central section. The central section is completely shielded by the wind splitter, so that the air carried by the rotor blades here is not directed against the incoming air. The vertical wind splitter is also a comparatively simple but effective flow-guiding element, directing the incoming air directly onto the rotor blades. Due to its projection on both sides over the rotor axes into the outer sections, this is achieved in such a way that the redirected air strikes a radially outer section of the rotor blades at a nearly right angle, thus achieving maximum effectiveness without causing a blockage.

[0009] The wind splitter particularly preferably has a closed inflow surface along which the inflowing air from the central region is guided towards the rotors without unnecessary further deflection. The wind splitter further preferably has a V- or U-shaped convex contour on the inflow side, viewed in horizontal cross-section. The terms "convex" and "concave" are not generally restricted to rounded contours, but also include contours with a bend. The wind splitter preferably has a convex inflow surface with a rounded leading edge. The rounded leading edge particularly preferably has a radius of at least 5%, preferably at least 10%, of the distance between the rotor axes. All of these advantageous embodiments have a simple and effective design in common.The contour of the wind divider, viewed in horizontal cross-section, is preferably also convex on the sides of the leading edge and particularly preferably convex all the way to the outer regions. This design ensures that the air flow entering the housing on the upstream side is deflected less and less in the direction of flow until, ideally, it flows essentially perpendicular to the plane of the rotor axes. The deflection occurs continuously, so that crossflows or turbulence are largely avoided. This can significantly increase efficiency. The closed front side can also have horizontal guide elements, such as fins or grooves, to promote laminar flow along the surface.

[0010] Advantageously, the rotors are arranged in such a way that the volumes swept by the rotor blades of both rotors overlap during rotation.

[0011] This design, also referred to herein as interlaced rotors, is generally known. However, in combination with the wind splitter extending into the outer areas on both sides, it offers the additional advantage of narrowing the central area, while still allowing the wind splitter to be kept correspondingly narrow relative to the rotor diameter. This, in turn, has the advantage, given the aforementioned contour of the inflow surface, that the wind splitter can also have a smaller depth. Overall, this allows wind resistance to be kept even lower while maintaining the same optimized contour.

[0012] According to an advantageous embodiment, the wind turbine further comprises a gear that synchronizes the rotor rotations.

[0013] Such wind turbines with synchronizing gearboxes are known, for example, from DE 10 2017 102 816 A1. As described in this document, the synchronizing gearbox offers the possibility of equipping the turbine with a single generator, to which the torques of both rotors are transmitted via the gearbox. Mechanical synchronization also serves to minimize imbalance in the rotor arrangement due to different rotation speeds or different torques. Finally, mechanical synchronization ensures in a simple and reliable way that contact between the rotor blades cannot occur, even when the rotor volumes overlap.

[0014] Preferably, the vertical wind divider has a tear-off edge on both sides in the outer areas.

[0015] The trailing edge supports the effect mentioned above of directing the incoming air specifically to the outer areas of the rotor blades in order to achieve high efficiency.

[0016] Particularly preferred are the separation edges, viewed in horizontal section, at an acute angle. This angle, in turn, ensures improved airflow in the aerodynamic range of laminar flow.

[0017] The separation edges each have an edge radius of at most 10%, preferably at most 5%, particularly preferably at most 3% and especially preferably at most 1% of the distance between the rotor axes.

[0018] Assuming rotor diameters, which in practice are typically 0.5 m to 2.0 m, preferably 1.0 m to 1.5 m, the limit values ​​result in absolute edge radii between approximately 0.4 cm and 8 cm, depending on the rotor diameter. A lower limit is determined partly by manufacturing technology and partly by mechanical stability. The edge radius is therefore advantageously at least 0.1 mm absolute and preferably at least 0.5 mm.

[0019] The wind divider advantageously has a double-concave surface on the back in the horizontal cross-section.

[0020] It is particularly preferred that there is a gap of uniform width between the double-concave rear side of the wind divider and the volumes swept by the rotor blades during rotation.

[0021] This feature can also be referred to as a concentric arrangement because, as a result, the cylindrical outer surfaces of the rotor volumes and the two concave surface sections of the rear side of the wind splitter are arranged concentrically to one another. This feature complements the feature of an acute angle of the separation edge in a particularly advantageous way. In the area of ​​the separation edge, the air flowing towards the wind splitter and the air partially recirculated in the central area meet at precisely this acute angle and thus almost parallel to one another, which minimizes the occurrence of turbulence. The primary flow of the incoming air therefore maintains its direction. With this geometry, the acute angle of the separation edge results almost inevitably from the feature of the wind splitter protruding beyond the central area in conjunction with the feature of a rear side concentric to the rotor volume.

[0022] The vertical air guiding elements preferably have a convexly curved surface towards the center of the housing in the horizontal cross-section on the upstream side.

[0023] This ensures an increase in the wind capture surface area on the upstream side and, at the same time, a deflection of the air entering the housing on the upstream side so that it flows essentially perpendicular to this plane in the plane of the rotor axes. In conjunction with a convex contour of the wind divider in horizontal cross-section to the side of the leading edge, preferably up to the outer regions, the vertical air guiding elements together with the wind divider form a funnel. The funnel preferably has a decreasing degree of taper up to its mouth at the level of the trailing edge of the wind divider. This design has the effect that the air flow entering the housing on the upstream side is deflected less and less in the direction of flow until, ideally, it flows essentially perpendicular to this plane in the plane of the rotor axes. The deflection takes place continuously, so that cross flows or turbulence are largely avoided.In this way, efficiency can be significantly increased.

[0024] For the same purpose, the sections of the inflow surfaces of the wind splitter, on the one hand, and the vertical air guide elements, on the other hand, which are opposite each other horizontally and parallel to the plane of the rotor axes, are particularly preferably arranged essentially mirror-symmetrically. This means that their angles of attack relative to the plane of the rotor axes and their curvature are opposite and do not differ from each other by more than 20%.

[0025] The housing preferably has a substantially horizontal air guiding element on the top and bottom.

[0026] These at least ensure that the air fed into the housing cannot escape upwards or downwards and thus increase the yield of the system,

[0027] The horizontal air guiding elements preferably form an inlet opening that narrows vertically in the direction of the rotors.

[0028] In this design, the horizontal air guide elements serve to harness the airflow above and below the rotor surface, at least to the extent that the structure of the wind turbine already provides a surface for the airflow. In other words, the horizontal air guide elements increase the wind capture area, which ensures overall greater airflow and higher speed within the housing.

[0029] The horizontal air guiding elements also preferably have a convexly curved surface towards the center of the housing in the vertical cross-section on the upstream side.

[0030] As with the vertical air deflectors, this geometry increases the wind capture surface on the upstream side and simultaneously deflects the air entering the housing on the upstream side so that it flows essentially perpendicular to the plane of the rotor axes. The vertical air deflectors and the horizontal air deflectors preferably form a circumferentially closed frame.

[0031] The circumferentially closed frame preferably has a leading edge on the inflow side, which runs continuously in front of the plane of the rotor axes, preferably in front of the volumes swept by the rotor blades during rotation and particularly preferably in front of the separation edges of the vertical wind divider.

[0032] This ensures that the air fed into the housing cannot escape upwards or downwards before it hits the rotors,

[0033] The vertical air guiding elements are advantageously adjustable in shape so that they form a horizontal air flow opening with variable width.

[0034] This measure allows the system to be adapted to different wind speeds.

[0035] The rotor blades of both rotors advantageously have concavely curved surfaces in the outer area on the upstream side in the horizontal cross-section.

[0036] The useful side of the rotors is thus located directly in the air flow that is directed through the housing.

[0037] Further features and advantages of the invention are explained below with reference to the accompanying drawings. These show:

[0038] Figure 1 is a front view of an embodiment of the wind turbine according to the invention;

[0039] Figure 2 is a sectional view of the embodiment according to Figure 1 along the plane

[0040] A - A;

[0041] Figure 3 is a bottom view of the embodiment according to Figure 1;

[0042] Figure 4 is a side view of the embodiment according to Figure 1 and Figure 5 is a perspective view of the embodiment of the wind turbine according to the invention according to Figure 1 without showing the rotors.

[0043] The wind turbine according to the invention is described below with reference to Figures 1-5, which show the same exemplary embodiment in various views. Where individual aspects are only visible in certain views, reference is made to a specific figure. In Figure 1, a sectional plane is shown as a horizontal dash-dotted line. The corresponding section A-A, looking upward, is shown in Figure 2.

[0044] The wind turbine 10 has a housing 12 in which an arrangement of two rotors 16, 17 mounted for counter-rotation about vertical rotor axes 14, 15 is arranged. The rotors 16, 17 each have a plurality, in this case four, of rotor blades 18, the rotation of which each describes a circular cylindrical volume. The circumferences of the volumes are shown in the projection of the sectional view in Figure 2 as dashed circumferential circles 20, 21. The volumes of both rotors 16, 17 intersect in the center of the housing 12. The rotor blades 18 of both rotors 16, 17 each have a concavely curved surface 22 in cross-section on the upstream side. In the vertical direction, the rotor blades 18 are straight. The two vertical rotor axes 14, 15 also run vertically and lie in a common plane 24.

[0045] The housing 12 has an inflow side 26 and a rear side 28. Transversely thereto, the wind turbine 10 can be divided into three regions: a central region 30, which, in a vertical projection onto the plane 24, is located between the vertical rotor axes 14 and 15, and two outer regions 32, 33, which, in a vertical projection onto the plane 24, are each arranged outside the vertical rotor axes 14 and 15.

[0046] On each side of the arrangement of the two rotors 16, 17 in the outer regions 32, 33, the housing 12 has a vertical air guide element 34, 35. Each of the vertical air guide elements has a convexly curved surface 36 or 37 on the upstream side toward the center of the housing. In the vertical direction, the two air guide elements 34, 35 are straight.

[0047] As an alternative to the embodiment shown here, the vertical air guiding elements 34, 35 can also have a central bulge in relation to the vertical direction, which is suitable for deflecting the air flow in the vertical direction somewhat towards the center of the housing.

[0048] In the central region 30 and on the upstream side in front of the arrangement of the rotors 16, 17, the housing 12 has a vertical air splitter 40. This air splitter 40 is designed and arranged relative to the vertical rotor axes 14, 15 such that both rotors 16, 17 are exposed to air flow in the outer regions 32, 33, with the vertical air splitter 40 extending into the outer regions 32, 33 on both sides. In this embodiment, the air splitter 40 has a preferably sharp separation edge 42, 43 in each of the outer regions 32, 33. The separation edges 42, 43 increase the precision of the alignment of the incoming air to the regions of the rotor blades 18 that are located radially far outward relative to the vertical rotor axes 14, 15.

[0049] The orientation of the air flow is also promoted by a closed inflow surface 44, which comprises a rounded leading edge 46 at the foremost end of the wind divider 40 on the upstream side. Overall, the wind divider 40 therefore has, viewed in horizontal cross-section, a V-shaped convex contour on the upstream side, which extends into the outer regions 32, 33, i.e., up to the separation edges 42, 43, and is also convex everywhere up to there. Together with the surfaces 36, 37 of the two air guide elements 34, 35, which are convexly curved towards the center of the housing, the inflow surface of the wind divider forms two funnels, which have a decreasing degree of taper up to their mouth at the level of the separation edges 42, 43. The air flow entering the housing is deflected less and less in the direction of flow and is aligned essentially perpendicular to the plane 24.In particular, the deflection is continuous, so that crossflows or turbulence are largely avoided. The opposing sections of the inflow surfaces 36, 37, 44 of the wind divider 40, on the one hand, and the vertical air guide elements 34, 35, on the other, are arranged essentially mirror-symmetrically to a vertical plane in the center of each funnel, which plane is perpendicular to plane 24.

[0050] At the rear, the wind splitter 40, viewed in horizontal cross-section, has a double-concave surface 48. As can be seen in Figure 2, a uniformly wide gap 50, 51 is formed between the double-concave surface 48 and the volumes 20, 21 swept over by the rotor blades 18 during rotation. This causes, among other things, a deflection of the air flowing back in the central region between the rotors 16 and 17 in directions parallel to the plane 24. This air flow meets the incoming air deflected by the inflow surface 44 of the wind splitter 40 downstream of the separation edges 42, 43 at an acute angle. Accordingly, the separation edges 42, 43 are not only preferably sharp-edged, but they also have an acute angle. This avoids turbulence at the separation edges 42, 43, which could represent air resistance and reduce efficiency.

[0051] As can be seen particularly better in Figure 5, in which the rotors have been omitted for reasons of clarity, the housing 12 has a base plate 60 on its underside and a cover plate 62 on its top. The vertical air guide elements 34, 35 are mounted at the top and bottom of the base plate 60 and the cover plate 62 by means of fastening elements 52, 53 at their rear ends. In order to make the vertical air guide elements adjustable, they can also have guide carriages instead of the fastening means, which are guided on the base plate 60 and the cover plate 62. When moved, the carriages follow the circumferential line of the rotors 16, 17, which combines a pivoting movement of the vertical air guide elements 34, 35 with a forward or backward movement such that the vertical air guide elements 34, 35 form a horizontal inlet opening with a variable width.

[0052] The housing 12 further comprises a substantially horizontal air guide element 64, 66 on its top side and on its bottom side. In this exemplary embodiment, the lower horizontal air guide element 64 is integrally formed on the base plate 60, i.e., it forms a physical component thereof, just as the base plate 60 forms a functional part of the lower horizontal air guide element 64. Similarly, the upper horizontal air guide element 66 is integrally formed on the cover plate 62 and forms a physical component thereof, just as the cover plate 62 forms a functional part of the upper horizontal air guide element 66. Viewed in vertical cross-section, both horizontal air guide elements 64, 66 together form an inlet opening that narrows vertically toward the rotors 16, 17. Furthermore, they each comprise, on the inlet side, a surface 68, 70 that is convexly curved toward the center of the housing in the vertical cross-section.

[0053] The vertical air guiding elements 34, 35 also form together, when viewed in vertical cross-section, an inlet opening which narrows horizontally in the direction of the rotors 16, 17.

[0054] The vertical air guiding elements 34, 35, together with the horizontal air guiding elements 64, 66, form a circumferentially closed, funnel-shaped frame. On the upstream side, the frame has a leading edge 72 which runs continuously in front of the plane of the rotor axes, preferably in front of the volumes swept by the rotor blades during rotation or, as shown here, particularly preferably in front of the edges 42, 43 of the vertical wind divider 40. As shown here, a circumferentially closed frame can also be referred to if the vertical air guiding elements 34, 35 are laterally offset slightly rearward and inward relative to the cover plate 62 and the base plate 60. It is crucial that the leading edge 72 does not recede at any point into the space enclosed by the vertical air guiding elements 34, 35 and the horizontal air guiding elements 64 and 66, up to the area of ​​the rotors 16, 17.This prevents air flowing into the housing 12 from escaping from the housing 12 horizontally and transversely to the flow direction before reaching the rotors 16, 17.

[0055] Figures 3 and 4 show a gear assembly 74 arranged beneath the base plate 60, which rotationally connects the rotor shafts. This ensures the synchronization required due to the overlap or interlacing of the rotors 16, 17. It also allows the use of only one generator (not shown) directly or indirectly connected to the gear assembly 74 to convert the rotational energy into electrical energy.

[0056] Furthermore, a housing base 78 is arranged below the base plate 60, with which the housing 12 is mounted so as to be rotatable about a vertical pivot axis 76. The pivot axis 76 runs opposite the direction of flow in front of the plane 24 of the rotor axes 14, 15. This results in the airflow acting on the rotors automatically pivoting the wind turbine "into the wind." A pivot pin 84 extends through the housing base 78, around which the housing base 78 is rotatably mounted. The housing base 78 is also connected to the base plate 60 by means of struts 82 for stiffening purposes.

[0057] Furthermore, three stiffening ribs 80 are provided under the base plate 60 and on the cover plate 62, respectively. These stiffen the base plate 60 and the cover plate 62, particularly in the area of ​​the rotor shafts, in order to increase the load-bearing capacity and dampen the vibration behavior of the turbine or adjust the vibration frequency so that residual vibrations do not cause damage to the turbine. The base plate 60 itself, the housing base 78, the stiffening ribs 80, and the struts 82 are part of a supporting structure for the wind turbine 10.

[0058] As can be clearly seen in Figure 4, the lower horizontal air guide element 64 shields parts of the supporting structure, and the upper horizontal air guide element 66 shields at least the stiffening ribs 80 there from the incoming air. This increases the air yield used for energy generation without simultaneously increasing the air resistance of the entire system 10, because these structural elements already provide a surface for the incoming air to attack.

[0059] List of reference symbols

[0060] 10 wind turbines

[0061] 12 housings

[0062] 14, 15 vertical rotor axis

[0063] 16, 17 Rotor

[0064] 18 rotor blades

[0065] 20, 21 Circumference line

[0066] 22 Surface of the rotor blade

[0067] 24 levels

[0068] 26 Inflow side

[0069] 28 Back

[0070] 30 central area

[0071] 32, 33 external area

[0072] 34, 35 vertical air guide element

[0073] 36, 37 Surface of the vertical air guide element

[0074] 40 vertical wind divider

[0075] 42, 43 tear-off edge

[0076] 44 Inflow area of ​​the vertical wind divider

[0077] 46 Leading edge of the inflow surface

[0078] 48 double-concave surface

[0079] 50, 51 gap

[0080] 52, 53 Fastening element

[0081] 60 base plate

[0082] 62 cover plate

[0083] 64, 66 horizontal air guide element

[0084] 68, 70 Surface of the horizontal air guide element

[0085] 72 leading edge

[0086] 74 Gear arrangement

[0087] 76 Swivel axis

[0088] 78 housing base

[0089] 80 Stiffening rib

[0090] 82 Strut

[0091] 84 pivot pins

Claims

Patent claims 1. Wind turbine (10) with a housing (12) and with an arrangement of two rotors (16, 17) which are mounted in the housing (12) in opposite directions about vertical rotor axes (14, 15) and each have a plurality of rotor blades (18), wherein the rotor axes (14, 15) lie in a plane (24), wherein the housing (12) has an inflow side (26) and a rear side (28), wherein the regions (30) which are located between the rotor axes (14, 15) in a vertical projection onto the plane (24) are referred to as central and the remaining regions (32, 33) as external, wherein the housing (12) has on both sides of the arrangement of the rotors (16, 17) in the external regions (32, 33) a vertical air guide element (34, 35), wherein the housing (12) in the central region (30) and upstream of the arrangement of the rotors (16, 17) has a vertical wind divider (40),wherein the vertical wind splitter (40) is designed and arranged relative to the vertical rotor axes (14, 15) in such a way that both rotors (16, 17) are subjected to air flow in the outer regions (32, 33) and wherein the vertical wind splitter (40) projects into the outer regions (32, 33) on both sides.

2. Wind turbine (10) according to claim 1, characterized in that the rotors (16, 17) are arranged such that the volumes of both rotors (16, 17) swept over by the rotor blades (18) during rotation overlap.

3. Wind turbine (10) according to one of the preceding claims, characterized by a gear (74) synchronizing the rotor rotations.

4. Wind turbine (10) according to one of the preceding claims, characterized in that the vertical wind divider (40) has a tear-off edge (42, 43) on both sides in the outer regions (32, 33).

5. Wind turbine (10) according to claim 4, characterized in that the separation edges (42, 43) have an acute angle.

6. Wind turbine according to claim 4 or 5, characterized in that that the separation edges (42, 43) each have an edge radius of at most 10%, preferably at most 5%, particularly preferably at most 3% and especially preferably at most 2% of the distance between the rotor axes (14, 15).

7. Wind turbine (10) according to one of the preceding claims, characterized in that the wind divider (40) has a double-concave surface (48) on the rear side in horizontal cross-section.

8. Wind turbine (10) according to claim 7, characterized in that there is a uniformly wide gap (50, 51) between the double-concave surface (48) of the wind divider (40) and the volumes swept over by the rotor blades (16, 17) during rotation.

9. Wind turbine (10) according to one of the preceding claims, characterized in that the vertical air guiding elements (34, 35) have, on the upstream side, in the horizontal cross-section, a surface (36, 37) which is convexly curved towards the center of the housing (12).

10. Wind turbine (10) according to one of the preceding claims, characterized in that the housing (12) has a substantially horizontal air guiding element (64, 66) on the top side and on the bottom side.

11. Wind turbine (10) according to one of the preceding claims, characterized in that the horizontal air guiding elements (64, 66) form an inflow opening which narrows vertically in the direction of the rotors (16, 17).

12. Wind turbine (10) according to claim 10 or 11, characterized in that the horizontal air guiding elements (64, 66) have on the upstream side in vertical cross-section a surface (68, 70) which is convexly curved towards the center of the housing (12).

13. Wind turbine (10) according to one of claims 10 to 12, characterized in that the vertical air guiding elements (34, 35) and the horizontal air guiding elements (64, 66) form a circumferentially closed frame.

14. Wind power plant (10) according to claim 13, characterized in that the circumferentially closed frame has a leading edge (72) on the upstream side, which is continuously in front of the plane (24) of the rotor axes, preferably in front of the Rotor blades (18) during rotation sweep volumes and particularly preferably in front of the separation edges (42, 43) of the wind divider (40).

15. Wind turbine (10) according to one of the preceding claims, characterized in that the rotor blades (18) of both rotors (16, 17) each have concavely curved surfaces (22) in the horizontal cross-section on the upstream side in the outer regions (32, 33).

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