阅读说明：本技术 用于风能设施的转子和风能设施 (Rotor for a wind power installation and wind power installation ) 是由 约亨·施滕贝格 豪克·马斯 于 2020-04-30 设计创作，主要内容包括：本发明涉及一种用于风能设施(100、200)、尤其功率大于1MW的风能设施(100、200)的转子(106、206),一种用于风能设施(100、200)的转子(106、206)的毂,和一种风能设施(100、200)。本发明尤其涉及一种用于风能设施(100、200)、尤其功率大于1MW的风能设施(100、200)的转子(106、206),包括：初级转子叶片(108、220、222、224),其中初级转子叶片(108、220、222、224)以第一纵向延伸从第一根部区域(226)延伸至第一叶尖(225)；次级转子叶片(112、230、232、234),其中次级转子叶片(112、230、232、234)以第二纵向延伸从第二根部区域延伸至第二叶尖,其中第一纵向延伸大于第二纵向延伸。(The invention relates to a rotor (106, 206) for a wind energy installation (100, 200), in particular a wind energy installation (100, 200) with a power of more than 1MW, to a hub for a rotor (106, 206) of a wind energy installation (100, 200), and to a wind energy installation (100, 200). The invention relates in particular to a rotor (106, 206) for a wind energy installation (100, 200), in particular a wind energy installation (100, 200) with a power of more than 1MW, comprising: a primary rotor blade (108, 220, 222, 224), wherein the primary rotor blade (108, 220, 222, 224) extends with a first longitudinal extension from a first root region (226) to a first tip (225); a secondary rotor blade (112, 230, 232, 234), wherein the secondary rotor blade (112, 230, 232, 234) extends with a second longitudinal extension from the second root region to the second tip, wherein the first longitudinal extension is larger than the second longitudinal extension.)

1. A rotor (106, 206) for a wind energy plant (100, 200), in particular a wind energy plant (100, 200) with a power of more than 1MW, comprising:

-a primary rotor blade (108, 220, 222, 224), wherein the primary rotor blade (108, 220, 222, 224) extends with a first longitudinal extension from a first root region (226) to a first tip (225);

-a secondary rotor blade (112, 230, 232, 234), wherein the secondary rotor blade (112, 230, 232, 234) extends with a second longitudinal extension from a second root region to a second tip,

-wherein the first longitudinal extension is greater than the second longitudinal extension.

2. The rotor (106, 206) of claim 1,

wherein the ratio of the second longitudinal extension to the first longitudinal extension is less than 0.75, less than 0.5, less than 0.3 or less than 0.1.

3. The rotor (106, 206) of any one of the preceding claims,

wherein the primary rotor blade (108, 220, 222, 224) has a pitch adjustment device for a rotational movement about a longitudinal axis of the primary rotor blade (108, 220, 222, 224) and/or

Wherein the secondary rotor blade (112, 230, 232, 234) has a pitch adjustment device for a rotational movement about a longitudinal axis of the secondary rotor blade (112, 230, 232, 234), and/or

The secondary rotor blade (112, 230, 232, 234) is configured to be stall controlled.

4. The rotor (106, 206) of any one of the preceding claims,

wherein the primary rotor blade (108, 220, 222, 224) and the secondary rotor blade (112, 230, 232, 234) are arranged at a hub.

5. The rotor (106, 206) of any one of the preceding claims,

wherein the primary rotor blade (108, 220, 222, 224) has a first longitudinal axis oriented between the first root region (226) and the first blade tip (225), and the secondary rotor blade (112, 230, 232, 234) has a second longitudinal axis oriented between the second root region and the second blade tip, and

the first longitudinal axis and the second longitudinal axis enclose an angle parallel to the direction of rotation, and/or

The rotor (106, 206) has an axis of rotation and the first and second longitudinal axes enclose substantially the same large angle with the axis of rotation.

6. The rotor (106, 206) of any one of the preceding claims,

wherein the primary rotor blade (108, 220, 222, 224) adjacent to the first root region (226) comprises a structural section (227) extending from the first root region (226) in a direction of a structural section length towards the first tip, and the structural section (227) has an inductance of less than 0.3, and/or less than 0.25, and/or less than 0.2.

7. The rotor (106, 206) of any one of the preceding claims,

wherein the second longitudinal extension is greater than the structural segment length.

8. The rotor (106, 206) of any one of the preceding claims,

wherein the secondary rotor blade (112, 230, 232, 234) has an inductance between 0 and 0.4, wherein preferably the secondary rotor blade has an inductance of less than 0.1, for example 0, in the region adjacent to the second blade tip and an inductance between 0.25 and 0.4, in particular between 0.3 and 0.35, for example 1/3, in the region adjacent to the second root region.

9. The rotor (106, 206) of any one of the preceding claims,

comprising two primary rotor blades (108, 220, 222, 224) and/or two secondary rotor blades (112, 230, 232, 234), wherein the primary rotor blades (108, 220, 222, 224) and the secondary rotor blades (112, 230, 232, 234) are arranged adjacent to one another and preferably enclose an angle of 90 ° in each case.

10. The rotor (106, 206) of any one of the preceding claims,

comprising three primary rotor blades (108, 220, 222, 224) and/or three secondary rotor blades (112, 230, 232, 234), wherein the primary rotor blades (108, 220, 222, 224) and the secondary rotor blades (112, 230, 232, 234) are arranged adjacent to one another and preferably enclose an angle of 60 ° in each case.

11. The rotor (106, 206) of any one of the preceding claims,

wherein at least one high lift system is provided at the secondary rotor blade (112, 230, 232, 234), wherein the at least one high lift system comprises or is constituted by:

-a leading-edge flap,

-a slotted flap which is provided with a slot,

-a flap of fullerenes,

-a vortex generator, and/or

-a gurney flap.

12. A hub for a rotor (106, 206) of a wind energy installation (100, 200) comprises at least three primary interface points for coupling with primary rotor blades and at least three secondary interface points for coupling with secondary rotor blades (112, 230, 232, 234).

13. A wind energy plant (100, 200) comprising a tower (102, 202) and a nacelle (104) provided at the tower (102, 202) with a rotor (106, 206) according to any of the preceding claims 1-11 and/or a hub according to claim 12.

Technical Field

The invention relates to a rotor for a wind energy installation, in particular a wind energy installation with a power of more than 1MW, to a hub for a rotor of a wind energy installation and to a wind energy installation.

Background

Wind power installations are known in principle. Modern wind power installations generally relate to so-called horizontal-axis wind power installations, in which the rotor axis is arranged substantially horizontally and the rotor blades pass over a substantially vertical rotor surface. Wind power installations generally comprise, in addition to a rotor arranged at the nacelle, a tower on which the nacelle with the rotor is arranged so as to be rotatable about a substantially vertically oriented axis. The rotor typically includes one, two or more rotor blades of equal length. Rotor blades are elongated, uniform length members, which are typically manufactured from fiber reinforced plastics.

In the construction of rotor blades for wind energy installations, a compromise must be found, in particular, between the maximum possible lift of the rotor blade, its aerodynamic resistance and the stability of the rotor blade. It is known in principle that airfoils of rotor blades that generate high lift at low wind speeds generally have high aerodynamic drag at higher wind speeds. Furthermore, it must be ensured in addition to the aerodynamic properties of the rotor blade during the construction that the rotor blade is subjected to wind pressures, which occur, for example, in the event of wind gusts. The requirements are generally defined as structural requirements. This requirement can generally be met more simply by means of an elongated rotor blade having a thick profile than by means of a rotor blade having a thin profile, since the predetermined stability can be achieved with a smaller material expenditure by means of a thick profile than by means of a thin profile.

The rotor blades of the rotor of a horizontal-axis wind energy plant are usually designed such that they reduce the speed in the flow duct by 1/3 of the original wind speed, which is also referred to as a betz optimization. The reduction is achieved by the induction of the rotor against the direction of the incident flow. The optimized rotor therefore opposes the oncoming air with a resistance just large enough to cause a reduction 1/3 in the oncoming flow velocity across the entire rotor rotation plane. This is also referred to as inductance. The inductance is related to the local circumferential velocity, the local lift coefficient, and the rotor blade depth at any location on the rotor blade. Thus the energy extracted from the wind is converted into electricity.

Rotors are usually designed for a specific rotational speed or a specific ratio of tip speed to incident flow speed, the so-called tip speed ratio. The lift coefficient and the rotor blade depth are then chosen such that an inductance of as much as 1/3 occurs over the entire rotor radius. However, it has proven to be practical to achieve an inductance of 1/3, in particular in the section of the rotor blade close to the hub, but rather the inductance generally has a small value. This results in a lower power of the wind energy installation in partial load operation.

EP 1255931B 1 describes a wind energy installation with two rotors arranged one behind the other, one rotor having a first diameter and the other rotor having a second diameter. The rotational speed of the second rotor is designed such that the tips of the rotor blades of said rotor have the same peripheral speed. To achieve this, the rotational speed of the second rotor is different.

The german patent and trademark office retrieves the following prior art from the priority application of the present application: DE 102009038076A 1, DE 102015113404A 1, DE 102017117843A 1, US 2012/0051916A 1, US 2016/0237987A 1 and WO 2007/057021A 1.

Disclosure of Invention

Based on this, it is an object of the present invention to provide a rotor for a wind energy installation, in particular a wind energy installation with a power of more than 1MW, a hub for a rotor of a wind energy installation and a wind energy installation, which reduce or eliminate one or more of the above-mentioned disadvantages. In particular, the object of the invention is to provide a solution for increasing the yield of a wind energy installation in partial load operation.

According to a first aspect, the object is achieved by a rotor for a wind energy installation, in particular a wind energy installation with a power of more than 1MW, comprising: a primary rotor blade, wherein the primary rotor blade extends with a first longitudinal extension from a first root region to a first tip; and a secondary rotor blade, wherein the secondary rotor blade extends with a second longitudinal extension from the second root region to the second tip, wherein the first longitudinal extension is greater than the second longitudinal extension.

The primary rotor blade extends from a first root region to a first tip. The length of the primary rotor blade between the root region and the first blade tip is in particular a longitudinal extension, which in modern rotors for wind energy installations may be greater than 50 m. The root region is in particular the region of the primary rotor blade, by means of which said primary rotor blade is arranged at the hub. The blade tip is the region of the primary rotor blade facing away from the hub.

In addition to the primary rotor blades, the rotor includes secondary rotor blades. The secondary rotor blade differs from the primary rotor blade in particular in that it has a smaller longitudinal extent. The length of the secondary rotor blade is therefore smaller than the length of the primary rotor blade. In operation, the difference can also be recognized by the rotating primary rotor blade passing over a circular surface having a larger diameter than the circular surface passed over by the secondary rotor blade.

The rotor described in this document is based on the knowledge that an unoptimized inductance deviating from 1/3 in the region of the rotor blades close to the hub reduces the power of the wind energy installation, in particular in the partial-load region. It is also known that the required rotor blade depth is related to the possible lift coefficient of the airfoil profile used. The lift coefficient cannot be arbitrarily high, but is limited by aerodynamic, physical limits. It follows that an optimized rotor blade may not be designed to be arbitrarily slim, but rather requires a certain minimum blade depth in order to achieve an optimized inductance at a given rotor speed and a given maximum lift coefficient.

In the region of the rotor blades close to the hub, there is the problem that the circumferential speed becomes smaller and theoretically approaches zero at the hub. In order to achieve an optimized inductance at the limit of the lift coefficient, the rotor blades have to be designed infinitely deep in the region close to the hub. However, this is not feasible from a constructional point of view. Furthermore, the airfoil at the blade root must have a high bending moment so that the structure is designed to be structurally thick, which in turn results in a further reduction in the achievable lift coefficient. Furthermore, a limitation of the maximum blade depth, which is typically in the range between 4m and 5m, is required for logistical reasons in order to ensure that the rotor blades can be transported on the street.

The root region of the rotor blade usually has a circular airfoil shape at the pitch-controlled wind energy installation in order to correspondingly support and rotate the rotor blade at the installation, in particular at the hub. Such a circular airfoil has a lift coefficient of zero, so that only a deviation from the optimum value of the inductance is possible. The pitch-controlled wind power installation therefore has an inductance deviating from the optimum in the region of the rotor blades close to the hub in a constructively dependent manner, so that the power is further reduced.

Furthermore, the invention is based on the knowledge that other aerodynamic optimizations of conventional rotor blades are not foreseeable. According to this knowledge, it is proposed that smaller secondary rotor blades be provided in the region of the rotor close to the hub. The secondary rotor blade is an additional rotor blade which is preferably arranged next to the primary rotor blade at the hub and increases the inductance of the rotor in the region close to the hub.

Preferably, the second longitudinal extension of the secondary rotor blade depends on the length of the region at the primary rotor blade where no optimized inductance is achieved. Preferably, the secondary rotor blade extends with such a second longitudinal extension that it covers a region of the rotor which, owing to the primary rotor blade, does not have an optimized inductance of 1/3.

The advantage of this solution is that the second root region is subjected to only a small bending moment due to the small second longitudinal extension and can be designed with a correspondingly small relative profile thickness. In this way, a higher glide ratio can be achieved at the secondary rotor blade than with a thick airfoil at the primary rotor blade. This makes it possible to operate the secondary rotor blades in a performance-optimized manner in part-load operation, in which the installation is operated at the design tip speed ratio. Thus, substantially up to the hub achieves an inductance of 1/3.

The rotor described according to the first aspect offers particular advantages for low wind installations, in particular, since the structural design of the primary rotor blades is meaningful here and the tower loads for the installation design are less critical.

In a preferred embodiment variant of the rotor, it is provided that the ratio of the second longitudinal extent to the first longitudinal extent is less than 0.75, less than 0.5, less than 0.3 or less than 0.1. The secondary rotor blade may for example be less than half the length of the primary rotor blade and thus less than 50% of the length of the primary rotor blade. It may furthermore be preferred that the secondary rotor blade is less than 30% of the length of the primary rotor blade. It is particularly preferred that the secondary rotor blade has a length of less than or equal to 20 meters. In this connection, special transport can be avoided and the costs and the logistics costs are not significantly affected compared to conventional rotors.

According to a further preferred embodiment of the rotor, it is provided that the primary rotor blade has a pitch adjustment device for a rotational movement about a longitudinal axis of the primary rotor blade. It is furthermore preferred that the secondary rotor blade is configured to be stall controlled. The stall controlled secondary rotor blade is preferably firmly fixed at the hub.

Such a rotor with pitch controlled primary rotor blades and stall controlled secondary rotor blades is a hybrid variant between stall controlled and pitch controlled wind energy installations. Furthermore, the secondary rotor blades may also be pitch controlled and have pitch adjustment means. If the rated power of the wind energy installation is achieved by means of the rotor and the rotor speed cannot be increased further, the primary rotor blade is operated with a smaller tip speed ratio by means of the pitch adjustment device, which leads to a flow separation that can occur at the secondary rotor blade. The inductance and the torque generated by the secondary rotor blades thereby generally decrease and the rotor efficiency generally decreases.

This is a desirable effect in the case of strong winds, so that an undesirable power surplus at the rotor can be avoided. This facilitates the operation of such facilities in storm control. Since the secondary rotor blade, due to its small second longitudinal extent, operates only at a small circumferential speed, the flow separation at the secondary rotor blade is not problematic both acoustically and aeroelastically.

According to a further preferred development of the rotor, it is provided that the primary rotor blade and the secondary rotor blade are arranged at the hub. The primary rotor blade and the secondary rotor blade are in particular arranged on a common hub.

The hub preferably has a primary interface location and a secondary interface location. The primary rotor blade is preferably arranged at the primary interface point. The secondary rotor blade is preferably arranged at the secondary interface point. The primary interface point is preferably designed such that the primary rotor blade can be rotatably arranged at the primary interface point. For example, the primary interface point may have a circular flange at which a bearing is arranged, wherein the primary rotor blade is arranged at the primary interface point in a rotating manner by means of the bearing.

Furthermore, the hub is preferably designed such that a pitch drive can be provided or arranged at it, so that the primary rotor blade can be moved in rotation about its longitudinal axis by means of the pitch drive. The secondary interface point is preferably designed such that the secondary rotor blade can be firmly fixed thereto.

The primary rotor blade and the secondary rotor blade are preferably arranged substantially at the same axial position with respect to the rotor rotation axis. In particular, the primary rotor blade and the secondary rotor blade are arranged substantially not offset from one another with respect to the rotor axis of rotation.

According to a further preferred development of the rotor, it is provided that the primary rotor blade has a first longitudinal axis oriented between the first root region and the first blade tip, and the secondary rotor blade has a second longitudinal axis oriented between the second root region and the second blade tip, and the first longitudinal axis and the second longitudinal axis enclose an angle parallel to the direction of rotation.

The longitudinal axes of the primary rotor blade and of the secondary rotor blade are not parallel by the angle enclosed by the longitudinal axes of the primary rotor blade and of the secondary rotor blade parallel to the direction of rotation. Preferably, an angle of 90 DEG or less, in particular 60 DEG or less, is provided between the longitudinal axis of the primary rotor blade and the longitudinal axis of the secondary blade. The direction of rotation is understood to mean the circumferential direction of the blade tip and/or of a circular surface over which the primary rotor blade and/or the secondary rotor blade passes during operation.

It may also be preferred that the rotor has an axis of rotation and that the first longitudinal axis and the second longitudinal axis enclose an angle of substantially the same magnitude as the axis of rotation.

Preferably, the rotor has an axis of rotation. The longitudinal axes of the primary rotor blade and of the secondary rotor blade preferably enclose an angle of substantially the same magnitude with the axis of rotation. This means, in particular, that the surface which is traversed by the primary rotor blade during operation substantially comprises the surface which is traversed by the secondary rotor blade during operation.

According to a further preferred embodiment of the rotor, it is provided that the primary rotor blade comprises, adjacent to the first root region, a structural section which extends from the first root region in the direction of the structural section length towards the first blade tip and which has an inductance of less than 0.3 and/or less than 0.25 and/or less than 0.2.

The structural section of the primary rotor blade enables a particularly good structural design of the primary rotor blade, since no aerodynamic optimization is preferably carried out. In particular, the structural section may have a small lift coefficient or a zero lift coefficient. In particular, high inductances are not substantially taken into account when designing the structural section. This reduces the cost of the primary rotor blade. In particular, the primary rotor blade can also be designed more securely. A structural section is to be understood in particular as a section of the primary rotor blade which is close to the hub.

The primary rotor blade with the structural section having a low inductance has a lower efficiency than the primary rotor blade with an optimized inductance in the region close to the hub. However, said non-optimized inductance of the primary rotor blade is compensated by the secondary rotor blade. The combination of a primary rotor blade with a structural section having a low inductance and a secondary rotor blade having an optimized inductance leads to a rotor having a higher efficiency than a rotor having known optimized rotor blades.

Any point extending in the radial direction of the rotor can be stated in percentages, wherein preferably 0% represents the root region and 100% represents the tip of the primary rotor blade.

The primary rotor blade preferably has an inductance of 0.25 to 0.4, in particular 0.3 to 0.35, particularly preferably 1/3, in the region of 30% and 100%. Between 30% and 0%, the inductance may gradually decrease and reach a substantially zero value at 0%, i.e. in the root region. In the region between 20% and 40%, the primary rotor blade can have an inductance greater than 1/3, so that over-induction occurs here. Preferably, the secondary rotor blade has a negative lift coefficient in the region where the primary rotor blade has an over-induction, in order to compensate for the over-induction of the primary rotor blade.

The structural section preferably has a higher relative thickness and less camber than conventional rotor blades. Thereby, separation can be avoided at a lower lift. The structural section has a geometry in the section adjoining the root region that is matched to the geometry of the blade root. The lift coefficient of the structural section is preferably between CL 0 and CL 3. It is particularly preferred that the lift coefficient in the region close to the hub, in particular between 0% and 30%, is smaller than the lift coefficient of conventional rotor blades. The blade depth can be kept constant compared to conventional rotor blades.

According to a further preferred development of the rotor, it is provided that the second longitudinal extent is greater than the structural section length. If the second longitudinal extent is greater than the structural section length, the secondary rotor blade skips over a region of the rotor which, due to the primary rotor blade, would have a low inductance, in particular an unoptimized inductance. By means of the inductively optimized secondary rotor blade, the region close to the hub, i.e. the structural section, can be optimally utilized inductively.

According to a further preferred embodiment of the rotor, it is provided that the secondary rotor blade has an inductance between 0 and 0.4, wherein preferably the secondary rotor blade has an inductance of less than 0.1, for example 0, in the region adjacent to the second blade tip and an inductance between 0.25 and 0.4, in particular between 0.3 and 0.35, for example 1/3, in the region adjacent to the second root region.

The small or zero inductance at the second blade tip is preferably selected accordingly, since the primary rotor blade usually has only a small inductance deficiency in this radial region, for example slightly less than 1/3. Only a small lack of inductance must therefore be compensated for by the secondary rotor blade, so that the secondary rotor blade can have a smaller inductance in this region. The more the inductance of the primary rotor blade decreases towards the hub, the greater the inductance of the secondary rotor blade becomes, so that the inductances of the two rotor blades at this point of the rotor radius add up to 1/3. It is particularly preferred that the local inductance of the secondary rotor blade, minus the local inductance of the primary rotor blade, is 1/3. For example, the inductance of the primary rotor blade is 0.15 at 15 meters from the hub. The inductance of the secondary rotor blade is then preferably 0.18 at 15 meters from the hub, which is approximately the difference between 1/3 and 0.15.

By means of the secondary rotor blade thus formed, the induction-optimized region of the rotor can be increased. In particular in the region close to the hub, the rotor can be designed inductively optimally. For example, with the secondary rotor blade described above, the area with an unaptimized inductance, i.e. less than 1/3, can be reduced by more than 50%.

According to a further preferred embodiment of the rotor, it is provided that the rotor comprises two primary rotor blades and/or two secondary rotor blades, wherein the primary rotor blades and the secondary rotor blades are arranged adjacent to one another and preferably enclose an angle of 90 ° in each case.

The two primary rotor blades are preferably arranged opposite one another at the hub. The two secondary rotor blades are preferably arranged opposite one another at the hub. In the preferred embodiment of the rotor, the longitudinal axes of the two primary rotor blades are preferably arranged parallel. The longitudinal axes of the primary rotor blades preferably enclose an angle of 180 ° with one another. The longitudinal axes of the secondary rotor blades preferably likewise enclose an angle of 180 ° with one another. It is furthermore preferred that the primary rotor blade and the secondary rotor blade enclose an angle of 90 ° with one another.

Such a rotor is constructed, in particular, as a four-bladed rotor, two rotor blades being long and two rotor blades being short.

According to a further preferred embodiment variant, it is provided that it has three primary rotor blades and/or three secondary rotor blades, wherein the primary rotor blades and the secondary rotor blades are arranged adjacent to one another and preferably enclose an angle of 60 ° in each case.

The primary rotor blades and the secondary rotor blades are preferably arranged such that a secondary rotor blade is arranged between each of the two primary rotor blades. The longitudinal axes of adjacent primary rotor blades preferably enclose an angle of 120 ° with one another in each case. The longitudinal axes of adjacent secondary rotor blades preferably likewise enclose an angle of 120 ° with one another in each case. It is also preferred that the longitudinal axis of the primary rotor blade and the longitudinal axis of the secondary rotor blade adjacent to the primary rotor blade enclose an angle of 60 ° with one another. Such a rotor is in particular of six-blade design, three rotor blades being of long design and three rotor blades being of short design.

The rotor can be advantageously improved in that a high-lift system is provided at the secondary rotor blade, wherein at least one high-lift system comprises or is designed as: leading edge flaps, slotted flaps, fuller flaps, vortex generators, and/or gurney flaps.

According to a further aspect, the object mentioned at the outset is achieved by a hub for a rotor of a wind energy installation, comprising at least three primary interface points for coupling with primary rotor blades and at least three secondary interface points for coupling with secondary rotor blades.

According to a further aspect of the invention, the object mentioned at the outset is achieved by a wind energy installation comprising a tower and a nacelle arranged at the tower, which nacelle has a rotor according to one of the embodiments described above and/or a hub according to the embodiments described above.

For further advantages, embodiment variants and embodiment details of the further aspects described and possible modifications thereof, reference is also made to the above description and modifications of the corresponding features of the rotor.

Drawings

Preferred embodiments are exemplarily illustrated in accordance with the accompanying drawings. The figures show:

FIG. 1 shows a schematic view of a wind energy plant;

FIG. 2 shows a schematic view of another wind energy installation with schematically shown inductances; and

fig. 3 shows a schematic view of a wind energy installation known from the prior art with schematically illustrated inductances.

Detailed Description

Fig. 1 shows a schematic view of a wind energy installation. Wind energy plant 100 has a tower 102 and a nacelle 104 on tower 102. At the nacelle 104, an aerodynamic rotor 106 is provided, which has three primary rotor blades 108 and three secondary rotor blades 112 and a nacelle 110. During operation of the wind power installation 100, the aerodynamic rotor 106 is set into rotational motion by the wind, so that the rotor of the generator or the aerodynamic rotor, which is coupled directly or indirectly to the aerodynamic rotor 106, is also rotated. A generator is disposed in nacelle 104 and generates electrical energy. The pitch angle of the primary rotor blades 108 may be changed by a pitch motor at a rotor blade root of the respective primary rotor blade 108.

The primary rotor blade 108 preferably has an inductance of about 1/3 in the region beginning at the respective tip toward the structural section. In the structural section, the primary rotor blade 108 is basically designed to meet the structural requirements and can have an inductance significantly lower than 1/3. The secondary rotor blade 112 has a smaller longitudinal extension than the primary rotor blade 108. The secondary rotor blade furthermore has an inductance of 1/3 adjacent to the root region and an inductance of 0 adjacent to the blade tip, respectively. The sum of the inductances of the primary rotor blade and the secondary rotor blade preferably adds up to 1/3 for each distance from the hub. The part of the rotor 106 in which the inductance is therefore below 1/3, in particular significantly below 1/3, is reduced in the present rotor 106 compared to the known rotor.

Fig. 2 shows a schematic view of another wind energy installation with schematically illustrated inductances. The wind energy installation 200 has a tower 202 with a rotor 206. The rotor has a flow guide sleeve 210 in the region of its axis of rotation. The rotor includes a first primary rotor blade 220, a second primary rotor blade 222, and a third primary rotor blade 224. Rotor 206 rotates about the rotational axis such that primary rotor blades 220, 222, 224 move in rotational direction 208.

The configuration of the primary rotor blade is illustrated below with the third primary rotor blade 224 as an example. The third primary rotor blade 224 extends from the tip 225 towards the root region 226. The tip and root region is understood in particular to be the end of the third rotor blade 224.

In the region of the third primary rotor blade 224 close to the hub, it has a structural section 227 which extends from the root region 227 in the direction of the structural section length towards the blade tip 225 and is shown in dashed lines. The structural section 227 is characterized by a low inductance. In particular, the inductance of the structural section 227 may be less than 0.3 and/or less than 0.25 and/or less than 0.2.

The section of the third primary rotor blade 224 adjoining the structural section 227 in the direction of the blade tip 225 preferably has an inductance of approximately 1/3. In particular, the inductance in said region may be between 0.25 and 0.5, in particular between 0.25 and 0.35. In the section adjacent to the blade tip 225, the third primary rotor blade 224 therefore has a substantially optimized inductance, which enables performance-optimized operation of the wind energy installation 200. However, in the region close to the hub, in particular in the radius corresponding to the structure section length 227, the primary rotor blades 220, 222, 224 are not inductively optimally designed.

The rotor 206 furthermore has a first primary rotor blade 230, a second secondary rotor blade 232 and a third secondary rotor blade 234. The secondary rotor blades 230, 232, 234 have a significantly smaller longitudinal extent than the primary rotor blades 220, 222, 224. The secondary rotor blades 230, 232, 234 have an inductance of zero at the respective blade tips, which then gradually rises towards the root region to a value of 0.25 to 0.35, in particular 1/3.

The root regions of the secondary rotors 230, 232, 234 experience a smaller bending moment due to the significantly smaller longitudinal extension. Thus, it can be configured to have a smaller relative airfoil thickness to achieve a higher glide ratio. Thus, the area of non-optimized inductance is shifted towards the hub direction and the total area of optimized inductance is increased. This is schematically illustrated in fig. 2 in terms of a first inductance region 240 and a second inductance region 250. The first inductance region 240 is the region of the rotor or rotor blade in which a substantially optimized inductance, in particular 1/3, is achieved. The second inductance region 250 is the region of the rotor 206 or of the rotor blade in which the deviation from the optimum inductance, in particular here an inductance of less than 1/3, is present.

In contrast, fig. 3 shows a conventional wind energy installation 300 having a tower 302 and a rotor 306, wherein the rotor has a first rotor blade 320, a second rotor blade 322 and a third rotor blade 324. The rotor 306 does not have secondary rotor blades. It can be seen that a second, significantly larger induction region 350, in which the optimized inductance of 1/3 is not achieved, is present via the region of the rotor blades 320, 322, 324 close to the hub. Accordingly, the first inductance region 340 is smaller, in which an optimized inductance can be achieved. Accordingly, the aerodynamic performance of the rotor 306 is less than the aerodynamic performance of the rotor 206 in the wind energy plant 200 shown in fig. 2.

List of reference numerals:

100 wind energy installation

102 tower

104 nacelle

106 rotor

108 Primary rotor blade

110 air guide sleeve

112 secondary rotor blade

200 wind energy installation

202 tower

206 rotor

208 direction of rotation

210 air guide sleeve

220 first primary rotor blade

222 second primary rotor blade

224 third primary rotor blade

225 blade tip

226 root region

227 structural section

230 first secondary rotor blade

232 second secondary rotor blade

234 third and fourth secondary rotor blades

240 first inductance region

250 second inductance region

300 wind energy installation

302 tower

306 rotor

310 air guide sleeve

320 first rotor blade

322 second rotor blade

324 third rotor blade

340 first inductance region

350 second region of inductance