Rotor blade for a rotor for wind turbines

Abstract

Rotor blade for a rotor (6) for wind turbines with a vertical axis of rotation, comprising an inner U-shaped rotor blade segment (2), an outer U-shaped rotor blade segment (3) and a blade-shaped rotor blade segment (4), wherein the inner U-shaped rotor blade segment (2) is arranged in the U-shaped opening of the outer U-shaped rotor blade segment (3) such that a U-shaped curved flow channel (5) is formed between the two U-shaped rotor blade segments (2, 3), characterized in that the immersion depth (E1) of the blade-shaped rotor blade segment (4) into the outer U-shaped rotor blade segment (3) is between 30% to 70%, preferably 50% of the profile depth (P1) of this outer U-shaped rotor blade segment (3) and the immersion depth (E2) of the blade-shaped rotor blade segment (4) into the inner U-shaped rotor blade segment (2) is between 20% to 60%, preferably 40% of the profile depth (P2) of this inner U-shaped rotor blade segment (2).

Description

[0001] The invention relates to a rotor blade for a rotor for wind turbines with a vertical axis of rotation.

[0002] Darrieus rotors typically utilize the lift forces generated on profiled rotor blades when wind flows around them to generate a rotary motion. Such rotors are referred to as lift rotors. Wind turbines with lift rotors in the form of Darrieus rotors or H-Darrieus rotors are generally known from the state of the art. In addition to lift rotors, so-called drag rotors are also commonly used for wind turbines with a vertical axis of rotation. Drag rotors utilize the dynamic pressure acting on the rotor blades when the wind flow is decelerated by the rotor blades to generate a rotary motion.

[0003] Furthermore, wind turbines with a rotor with rotor blades that utilize lift forces to generate a rotary motion and a rotor with rotor blades that utilize the dynamic pressure when the wind flow slows down are known, for example from DE 20 2009 007 926 U1.

[0004] From DE 35 05 489 A1 a blade for a wind turbine with a rotor that can rotate about a vertical axis of rotation is known, which consists of a symmetrically profiled main wing for utilising lift forces to generate a rotary movement and a shell-shaped leading edge slat arranged at a certain distance in front of the wing nose of the main wing for utilising the dynamic pressure to generate a rotary movement.

[0005] DE 41 20 908 C2 describes a flow receptor as part of a rotor for rotating in a circular path around a fixed pivot point. The flow receptor comprises a U-shaped, curved leading edge slat and a blade-shaped, curved main wing, which are arranged relative to one another such that the convex side of the leading edge slat faces the direction of rotation of the rotor and the concave side of the leading edge slat faces the main wing. Flows from the direction of the main wing are directed through the main wing into the concavely curved side of the leading edge slat, causing a dynamic pressure that is converted into a rotational movement. Flows from the direction of the leading edge slat flow around the blade-shaped, curved main wing, generating lift forces that are also converted into a rotational movement.

[0006] DE 10 2011 118 844 B3 describes a rotor blade for vertical wind turbines. It has a profile cross-section with a leading edge in the direction of rotor movement and two profile sides opposite each other of the profile side. One of the profile sides is designed as a lift profile side with an airfoil profile in the manner of a lift rotor, and the other profile side is designed as a drag profile side with a blade open against the direction of movement of the rotor blade in the manner of a drag rotor. This rotor blade also serves to generate a rotary motion, utilizing both the air flow in the direction of movement of the rotor blade via the dynamic pressure on the open blade and the air flow opposite to the direction of movement of the rotor blade via lift forces from the air flowing around the airfoil.

[0007] The solution described in DE 20 2015 003 173 U1, which proposes a rotor blade for a wind turbine rotor with a vertical axis of rotation, can be considered the closest prior art. This rotor blade is a further development of known rotor blades for wind turbine rotors with a vertical axis of rotation, which utilize both the dynamic pressure of flowing air on the rotor blade and the lift forces resulting from the air flowing around the rotor blade to generate a rotational movement.

[0008] The object of the invention is to further develop the above-mentioned solution, aiming at a significant improvement in efficiency.

[0009] The object of the invention is achieved by a rotor blade for a rotor for wind turbines with a vertical axis of rotation having the features of the first claim.

[0010] Claims 2 to 7 describe advantageous developments of the rotor blade according to the invention.

[0011] A rotor blade according to the invention for a rotor for wind turbines with a vertical axis of rotation comprises a blade-shaped rotor blade segment with a curved cross-section, hereinafter referred to as blade-shaped rotor blade segment, a rotor blade segment with a U-shaped cross-section, arranged in front of the blade-shaped rotor blade segment in the direction of movement of the rotor blade, hereinafter referred to as inner U-shaped rotor blade segment, and a second rotor blade segment with a U-shaped cross-section, hereinafter referred to as outer U-shaped rotor blade segment, arranged in front of the inner U-shaped rotor blade segment in the direction of movement of the rotor blade.

[0012] The two U-shaped rotor blade segments are designed and arranged in relation to one another in such a way that a U-shaped curved flow channel is formed between the inner and the outer U-shaped rotor blade segment.

[0013] The blade-shaped rotor blade segment and the two U-shaped rotor blade segments are arranged relative to each other such that the leading edge of the blade-shaped rotor blade segment, in the direction of movement of the rotor blade, extends approximately centrally along the opening between the two legs of the inner U-shaped rotor blade segment. The blade-shaped rotor blade segment functions, on the one hand, as a guide element, along which an air flow approaching the rotor blade in the direction of movement or at an angle to the direction of movement of the rotor blade is directed into the opening between the two legs of the outer U-shaped rotor blade segment and into the U-shaped curved flow channel.

[0014] The blade-shaped rotor blade segment also functions like an airfoil, generating lift force as a result of the airflow around it. The two U-shaped rotor blade segments offer resistance to the airflow introduced as described above, generating a force in the direction of movement of the rotor blade.

[0015] At the trailing edge of the blade-shaped rotor blade segment, in the direction of movement of the rotor blade, a separation edge is formed that extends the entire length of the blade-shaped rotor blade segment. This separation edge reduces or prevents the formation of vortices in the airflow surrounding the blade-shaped rotor blade, thereby further improving, i.e., increasing, the efficiency of the rotor blade.

[0016] When a rotor blade as described above is arranged as intended on a rotor for a wind turbine with a vertical axis of rotation, the rotor blade, when subjected to an airflow, causes the rotor to rotate or generates a torque at the rotor axis, both in the manner of a drag rotor and in the manner of a lift rotor. Due to the described arrangement of two U-shaped rotor blade segments, the torque component generated in the manner of a drag rotor predominates. It has been shown that the described arrangement of two U-shaped rotor blade segments in conjunction with the blade-shaped rotor blade segment enables effective utilization of an airflow with regard to generating a torque at the rotor axis of a rotor equipped with the rotor blades as described above.

[0017] When an air flow passes over a rotor with several rotor blades according to the invention, the rotor is set into a rotary motion as described, which is divided into a lift and a drag zone. Within the lift zone of the rotary motion, a significant increase in the lift effect is observed, which acts in the manner of a Flettner effect and leads to an increase in the rotor's efficiency.

[0018] A further significant increase in efficiency is achieved through a novel dimensioning and arrangement of the rotor blade segments of the rotor blade according to the invention, which was discovered on the basis of extensive empirical tests.

[0019] The novel arrangement and dimensioning of the U-shaped rotor blade segments and the blade-shaped rotor blade segment relative to each other is characterized by the degree of immersion of the blade-shaped rotor blade segment into the respective profile depths of the U-shaped rotor blade segments.

[0020] It has been shown that a particularly high increase in efficiency is achieved when the immersion depth of the blade-shaped rotor blade segment into the outer U-shaped rotor blade segment is between 30% and 70%, preferably 50% of the profile depth of this outer U-shaped rotor blade segment.

[0021] It has also been shown that the efficiency increases further if the immersion depth of the blade-shaped rotor blade segment into the inner U-shaped rotor blade segment is between 20% and 60%, preferably 40% of the profile depth of this inner U-shaped rotor blade segment.

[0022] The increase in efficiency is particularly well achieved when the profile depth difference between the inner U-shaped rotor blade segment and the outer U-shaped rotor blade segment is between 10% and 45%, preferably 25%.

[0023] To achieve sufficient rigidity, a rotor blade can have one to five locking elements. These elements, on the one hand, hold the rotor blade segments in position relative to each other and, on the other hand, channel the airflow transversely to the longitudinal axis of the rotor blade, thus preventing airflow in the direction of the longitudinal axis of the rotor blade. The distance between the locking elements along the longitudinal axis of the rotor blade should be between 400 mm and 800 mm.

[0024] A rotor can have between 2 and 6 rotor blades according to the invention, ie it can be designed with 2 to 6 arms.

[0025] The invention will be further explained below using an exemplary embodiment. The accompanying drawings show Fig. 1: schematically a rotor blade according to the invention and in Fig. 2: the cross-section of a rotor with rotor blades according to the invention.

[0026] Fig. 1 schematically shows a rotor blade 1 with an inner U-shaped rotor blade segment 2, an outer U-shaped rotor blade segment 3, and a blade-shaped rotor blade segment 4. The inner U-shaped rotor blade segment 2 is arranged in the U-shaped opening of the outer U-shaped rotor blade segment 3 such that a U-shaped curved flow channel 5 is formed between the two U-shaped rotor blade segments 2, 3. The two U-shaped rotor blade segments 2, 3 are dimensioned such that the U-shaped curved flow channel 5 has a constant cross-sectional area along the flow channel. The outer U-shaped rotor blade segment 3 forms the profile nose of the rotor blade 1 in the direction of movement of the rotor blade 1. The blade-shaped rotor blade segment 4 is positioned with its leading edge approximately centrally along the opening between the two limbs of the inner U-shaped rotor blade segment 2. It extends in a curved manner counter to the direction of movement of the rotor blade 1.The trailing edge of the blade-shaped rotor blade segment 4 forms the trailing edge of the rotor blade 1. The curvature of the blade-shaped rotor blade segment 4 corresponds to a circular path, preferably the circular path along which a rotor blade 1 arranged on a rotor 6 moves (cf. Fig. 2).

[0027] Caps 7 are arranged on the end faces of the rotor blade 1. The caps 7 position and mechanically hold the two U-shaped rotor blade segments 2, 3 and the blade-shaped rotor blade segment 4 relative to each other. In the longitudinal direction of the rotor blade 1, locking elements 8 are arranged in the U-shaped curved flow channel 5 and within the outer U-shaped rotor blade segment 3.

[0028] These blocking elements 8, on the one hand, hold the rotor blade segments in position relative to one another and, on the other hand, channel the air flow transversely to the longitudinal axis of the rotor blade 1 and thus prevent air flow in the direction of the longitudinal axis of the rotor blade 1. The distance between the blocking elements 8 in the direction of the longitudinal axis of the rotor blade 1 should be between 400 mm and 800 mm.

[0029] The outer U-shaped rotor blade segment 3 has a profile depth P1, which in the present embodiment is 300 mm. The inner U-shaped rotor blade segment 2 has a profile depth P2, which in the present embodiment is 120 mm.

[0030] The blade-shaped rotor blade segment 4 penetrates the outer U-shaped rotor blade segment 3 with an immersion depth E1, which in the present embodiment is 150 mm. The blade-shaped rotor blade segment 4 penetrates the inner U-shaped rotor blade segment with an immersion depth E2. The immersion depth E2 is 250 mm in the present embodiment.

[0031] Fig. Figure 2 shows schematically a 5-armed rotor 6 with rotor blades 1.1 to 1.5 according to Fig. 1 in cross-section. An arrow 9 illustrates the direction of rotation of the rotors 1.1 to 1.5. The other Fig. The arrows 10 shown in Figure 2 illustrate air flows. When the rotor blades 1.1 and 1.2 are positioned as shown in the right half of the figure, the air flows onto the two rotor blades 1.1 and 1.2 from behind or diagonally from behind. The air flow 10 is guided through the blade-shaped rotor blade segment 4 into the U-shaped curved flow channel 5 and into the space between the two legs of the inner U-shaped rotor blade segment 2. Both the first U-shaped rotor blade segment 2 and the outer U-shaped rotor blade segment 3 offer resistance to the air flow 10, so that a force is generated that drives the rotor blades in the direction of movement. The Fig. The circular arc segment A shown in Figure 2 illustrates the range of rotational movement of the rotor 6, which extends from the build-up of the drag effect to the range of full drag effect of the rotor blades 1.1 and 1.2 against the air flow 10. The circular arc segment B illustrates the transition from the drag area to the lift effect area. The rotor blade 1.3 is located in this transition area, in which the drive of the rotational movement changes from the drag effect to the lift effect. In the position of the rotor blades 1.4 and 1.5 shown in the left half of the image, the air flow 10 flows against the rotor blades 1.4 and 1.5 from the front or diagonally from the front. In the position of the rotor blade 1.4 shown on the far left and the rotor blade 1.5 shown bottom left, the air flow 10 flows around the blade-shaped rotor blade segment 4.When the air flows around the blade-shaped rotor blade segment 4, a lift force is generated, which also causes the rotor 6 to rotate.

[0032] The circular arc segment C illustrates this area of the lift effect of the rotational movement of rotor 6. In this area, an additional effect similar to that occurring in a Flettner rotor is observed, i.e., the airflow flowing toward the rotating rotor 6 is accelerated on one side of the rotating rotor 6 and decelerated on the other. This generates an additional force component that supports the rotation of rotor 6.

[0033] In the rotor blade 1.3. in Fig. 2, a rotor blade center line M was drawn. An angle of attack α illustrates the arrangement of the rotor blade 1.3 on its associated support element of the rotor 6. The angle of attack α can be 85° to 95°. It is permanently adjustable within this range. In the present example, the angle of attack α is 95°. The rotor blade 1.3 thus moves as a component of the rotor 6 on a circular path with an angle of attack α. Its front, formed in the direction of rotation of the rotor 6 by the outer U-shaped rotor blade segment 3, is slightly inclined outwards. The other Fig. The rotor blades 1.1, 1.2, 1.4 and 1.5 shown in Figure 2 are arranged with the same angle of attack α on the rotor 6. For the sake of clarity, the rotor blade center line M and the angle of attack α were divided into the rotor blades 1.1, 1.2, 1.4 and 1.5 of the Fig. 2 not shown. List of reference symbols 1 rotor blade 1.1 Rotor blade 1.2 Rotor blade 1.3 Rotor blade 1.4 Rotor blade 1.5 Rotor blade 2 inner U-shaped rotor blade segment 3 outer U-shaped rotor blade segment 4 blade-shaped rotor blade segment 5 U-shaped curved flow channel 6 Rotor 7 cap 8 Locking element 9 Arrow direction of rotation of the rotor 6 10 Air flow E1 Immersion depth of the blade-shaped rotor blade segment 4 into the outer U-shaped rotor blade segment 3 E2 Immersion depth of the blade-shaped rotor blade segment 4 into the inner U-shaped rotor blade segment 2 P1 Profile depth of the outer U-shaped rotor blade segment 3 P2 Profile depth of the inner U-shaped rotor blade segment 2 A circular arc segment B circular arc segment C circular arc segment M Rotor blade centerline α angle of attack QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] DE 20 2009 007 926 U1

[0003] DE 35 05 489 A1

[0004] DE 41 20 908 C2

[0005] DE 10 2011 118 844 B3

[0006] DE 20 2015 003 173 U1

[0007]

Claims

[1] Rotor blade for a rotor (6) for wind turbines with a vertical axis of rotation with an inner U-shaped rotor blade segment (2), an outer U-shaped rotor blade segment (3) and a blade-shaped rotor blade segment (4), wherein the inner U-shaped rotor blade segment (2) is arranged in the U-shaped opening of the outer U-shaped rotor blade segment (3) such that a U-shaped curved flow channel (5) is formed between the two U-shaped rotor blade segments (2, 3), characterized by that the immersion depth (E1) of the blade-shaped rotor blade segment (4) into the outer U-shaped rotor blade segment (3) is between 30% and 70%, preferably 50% of the profile depth (P1) of this outer U-shaped rotor blade segment (3) and the immersion depth (E2) of the blade-shaped rotor blade segment (4) into the inner U-shaped rotor blade segment (2) is between 20% and 60%, preferably 40% of the profile depth (P2) of this inner U-shaped rotor blade segment (2). [2] Rotor blade according to claim 1, characterized by that the difference between the profile depths (P1, P2) is between 10% and 45%, preferably 25% of the profile depth (P1) of the outer U-shaped rotor blade segment (3). [3] Rotor blade according to claim 1, characterized by that the two U-shaped rotor blade segments (2, 3) are designed and arranged relative to one another in such a way that the U-shaped curved flow channel (5) formed between the inner and the outer U-shaped rotor blade segment (2, 3) has a cross-sectional area that remains constant along the flow channel (5). [4] Rotor blade according to claim 1 or 2, characterized by that the curvature of the blade-shaped rotor blade segment (4) corresponds to the curvature of a circular path along which the rotor blade (1) moves when arranged on a rotor (6) when the rotor (6) rotates. [5] Rotor blade (1) according to claims 1 to 4, characterized bythat caps (7) are arranged on the end faces of the rotor blade (1), by means of which caps the U-shaped curved flow channel (5) between the first and the second U-shaped rotor blade segment (2, 3) and the space within the inner U-shaped rotor blade segment (2) in the longitudinal direction of the rotor blade (1) is closed. [6] Rotor blade (1) according to claim 5, characterized by that the caps (7) are designed for positioning and mechanically holding the rotor blade segments (2, 3, 4). [7] Rotor blade (1) according to claims 1 to 6, characterized by in that blocking elements (8) are arranged in the U-shaped curved flow channel (5) between the inner and outer U-shaped rotor blade segments (2, 3) and in the space inside the inner U-shaped rotor blade segment (2), by means of which blocking elements the U-shaped curved flow channel (5) and the space inside the inner U-shaped rotor blade segment (2) are divided in the longitudinal direction of the rotor blade (1).

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