CH713477A1 - Wind turbine. - Google Patents

Abstract

The invention relates to a wind energy plant (11) having a rotor (13) with a plurality of rotor blades, a diffuser (21) with a wind inlet opening (23) and a wind outlet opening (25), which diffuser (21) supports the rotor (13). and the generator rotationally symmetrical sheathed and on which the generator is held against rotation. The inner diameter of the diffuser (21) is the smallest at the location where the rotor blades (15) are positioned, whereby the diffuser (21) has a constriction (33) at that location.

Description

description

Field of the Invention The invention relates to a wind turbine according to the preamble of claim 1.

Background Art Wind turbines in which the rotor is covered with a diffuser are known in the prior art. The diffuser is a shell of the rotor, which widens in the flow direction. The diffuser causes an additional circulation flow whose velocity components in the diffuser are directed in the same direction with the wind flow and thus amplifies it. The power concentration results from the formation of a pressure difference in front of and behind the rotor. However, the opening angle of the diffuser is limited, since at too large widening the flow breaks through the diffuser and the achievable flow rates are lower. In order to increase the expansion without stall long and large diffusers are necessary, which are therefore expensive and strong winds provide a large attack surface.

Swiss Patent Application No. 702,241 A2 describes a small wind turbine having a wind power generator with a flexible, aerodynamic shroud that can be collapsed to a minimum for transportation. The textile skin is thereby slipped over a correspondingly shaped skeleton consisting of inflow, support and Ab-strömring stretched and fixed. After removal of the struts and the flexible, textile double hull, the skeleton basket can be pushed from the back to the front and a volume saving of about 60% can be achieved. The middle ring of the skeleton is the support ring, which also carries the tripod strut. The tripod support foot is attached to the support ring as a continuation of the tripod strut. Attached to the diffuser by means of webs is a Fowler with a wing cross-section, which serves to intensify the flowing flow wind flow.

The German Utility Model DE-U-20 2007 006 015 discloses a wind turbine with a jacket comprising the turbine with generator. This wind turbine is characterized by the fact that flow deflection vanes are used in the annular channel. This allows an opening angle of the diffuser of up to 75 degrees. At the end of the outer side of the casing, a flow ring is provided, wherein the surface of the inlet opening is larger than that of the outlet opening.

DE-OS-3 049 791 discloses a wind power plant with a vertical chimney. To avoid the tearing off of the flow at a vertical diffuser outlet is proposed to use a Windhutze that deflects the above emerging from the chimney vertical flow partially or completely in the horizontal wind direction. The wind diffuser can be expanded diffuser-shaped and complemented by a wing profile-like ring.

US Pat. No. 4,132,499 discloses a wind powered energy harvesting apparatus having a shroud and a turbine with rotor blades disposed in the shroud at a throat. The device has an inlet area upstream of the turbine, which tapers to the narrowing and then expands again. In addition, a plurality of stator blades are provided, which are disposed between the turbine housing and the enclosure to support the turbine housing and to direct the air to the rotor blades. Both rotor and stator blades have a wing-like profile. In order to prevent the tearing off of the flow, a plurality of air channels is provided, which extend from the outer surface of the envelope to the internal surface. Through the channels described an air flow of high kinetic energy is passed from outside the envelope into the boundary layer of the flow in the diffuser. This has the advantage that the length of the diffuser section can be kept smaller. According to one embodiment, an annular wing may be provided, which adjoins the outlet of the diffuser and has a significantly larger opening angle than the rear portion of the diffuser.

A problem with wind turbines is that the diffuser begins to vibrate at higher wind speeds. This can lead to the extent that the wind turbine must be taken out of service.

OBJECT OF THE INVENTION From the disadvantages of the described prior art, the object initiating the present invention results in improving the efficiency of a generic wind turbine with a diffuser. Yet another goal is to provide a wind turbine, which show a quiet running behavior even with a stronger Wink. Another goal is that the diffuser brings a high energy yield in a compact design.

Description: The invention relates to a wind energy plant with a rotor having a plurality of rotor blades, which is arranged to rotate freely about a rotation axis, a generator which is connected to the rotor and converts the wind energy into electrical energy when the rotor rotates, and a diffuser. The diffuser has a wind inlet opening and a wind outlet opening and encloses the rotor and the generator rotationally symmetrical. The generator is held against rotation on the diffuser, wherein the diffuser has a constriction at the location where the rotor blades are positioned. The diffuser has an inlet region with an inner side facing the rotor and curved in the direction of the rotor, and an outlet region with an outer side facing away from the rotor and curved in the direction of the rotor, the diffuser having at the inlet opening a front edge between the inner side and the outer side and at the Outlet opening forms a trailing edge between the inside and the outside.

The wind turbine according to the invention is characterized in that at the rear edge of the diffuser an angled flow ring is placed, wherein an air channel is formed between a first leg of the flow ring and the outside. Measurements in the wind tunnel have shown that the energy yield with the flow ring is significantly higher than without a flow ring. It is important that the angle between the first and the second leg is advantageously between 100 and 140 degrees, preferably between 110 and 130 and particularly preferably between 124 and 136 degrees. Surprisingly, this geometry has yielded particularly high energy yields in the wind tunnel.

In a preferred embodiment of the invention, the inside is more curved in the direction of the rotor than the outside. As a result, a higher wind speed is achieved on the inside than on the outside. The wind is therefore accelerated in the flow channel of the diffuser, resulting in an improved efficiency of the wind turbine.

It has proved to be expedient if the inner diameter of the inlet opening is smaller than the inner diameter of the outlet opening. This allows the diffuser to have an extended spout, which results in less wind turbulence on the inside.

In a further particularly preferred embodiment of the invention, the diffuser in the longitudinal cross section has the shape of two opposing symmetrical airfoil profiles, wherein the more curved sides of the airfoils are facing each other. In this case, the inside of the diffuser has an increased curvature, starting at the wind inlet opening, so that the constriction is positioned closer to the wind inlet opening than to the wind outlet opening. After the constriction, the curvature of the inside is reduced compared to the curvature in front of the constriction. As a result, an extended outlet of the flow channel is formed. The extended spout leads to a calming of the flow. The fact that the outside of the diffuser is less curved, it comes to the wing theory according to a higher wind speed on the inside than on the outside.

Conveniently, the angle between the straight line connecting the constriction and the trailing edge and the horizontal is between 7 and 21 degrees, preferably between 10 and 18 degrees and particularly preferably between 13 and 15 degrees on the airfoil. These angular sizes lead to a smaller curvature of the inside of the bottleneck than before the bottleneck.

Conveniently, at the airfoil profile, the angle between the straight line connecting the constriction and the leading edge and the horizontal between 10 and 40 degrees, preferably between 15 and 30 degrees, and more preferably between 17 and 21 degrees. Since this angle is greater than the angle defined in the last paragraph, the curvature in front of the constriction is greater than the curvature after the constriction and the constriction is closer to the leading edge than to the trailing edge.

The invention is also preferably characterized in that the angle between the tangent, which extends through the trailing edge and rests on the outside within the airfoil, and the horizontal between 1 and 3 degrees and preferably between 1.5 and 2 degrees is smaller than the angle described in the penultimate paragraph. As a result, the diffuser has a tapered trailing edge, as is customary for wings.

In a further preferred embodiment of the invention, the angle between the tangent, which extends through the trailing edge and rests on the outside outside of the airfoil, and the horizontal between 4 and 8 degrees and preferably between 5 and 7 degrees. Due to this small angle, the curvature of the outside of the diffuser is less than the curvature of the inside of the diffuser, which is absolutely necessary for the speed increase in the flow channel.

With preference, the defined angle of attack between the chord and the horizontal between 5 and 10 degrees and preferably between 7 and 8 degrees. The angle of attack is rather low, since the buoyancy for a diffuser is of no importance and only loads the material of the diffuser.

Conveniently, the leading edge is rounded, whereby the air resistance of the diffuser can be reduced.

On the production side, it is preferred if the diffuser is free of an undercut in the flow direction. This allows simple molds to be used and the diffuser is easy to demould when injection molded. The diffuser is therefore preferably made of a plastic.

Conveniently, the generator is connected by means of struts with the diffuser, wherein the struts are fixed to plates which are embedded in the diffuser body. This ensures a stable construction of the diffuser body.

Advantageously, the diffuser is arranged on a rotary foot. As a result, the diffuser can optimally put each in the wind.

Advantageously, the axis of rotation of the rotary foot is approximately in the plane of the inlet opening or located in the flow direction at a small distance in front of this. This has the advantage that the diffuser even with stronger

Wind does not start to swing. By "about" is meant that the axis of rotation can be up to 8 cm, preferably up to 5 cm in the flow direction seen after the plane of the inlet opening.

Conveniently, the diffuser is arranged on arm, which is rotatably connected to the diffuser.

Advantageously, a damping device for damping the rotational movement of the diffuser is provided in the rotary foot. This has the advantage that the diffuser is stable in the wind even with larger wind strengths.

Preferably, the damping device is based on the displacement principle. This has the advantage that different degrees of torque can be effectively damped.

Conveniently, the damping device is realized by an annular channel for receiving a liquid is provided in the Drehfuss between a fixed, cylindrical part and the arm rotatably connected to the housing, wherein between a fixedly connected to the housing and received in the annular channel driver and the Ring channel a gap is present.

The rotary foot with integrated damping device described is an independent aspect of the present invention and can in principle be used with other than the inventive diffuser.

Another aspect of the invention relates to a diffuser for sheathing the rotor of a wind turbine with the diffuser features described above. With such a diffuser, existing wind turbines can extensively retrofit rotor blades.

Further advantages and features will become apparent from the following description of an embodiment of the invention with reference to the figures. It shows in not to scale representation:

1 shows a cross section through the upper longitudinally symmetrical part of a diffuser of a wind turbine;

Fig. 2: different views of a arranged on a swivel diffuser with attached flow ring;

Fig. 3: A perspective view of the diffuser of Fig. 2;

Fig. 4: The pivot of the diffuser of Fig. 2; and

Fig. 5: A side view of the diffuser, partly in section, and a detailed view of the flow ring;

Fig. 6: A perspective view of a rotary foot;

Fig. 7: The rotary foot of Fig. 6 in section.

In Fig. 1, a wind turbine is shown, which is generally designated by the reference numeral 11. FIG. 1 shows a cross section through the wind energy plant 11, only the upper part of the cross section being shown. The lower part is longitudinally symmetrical to the upper part.

The wind turbine 11 comprises a rotor 13 with a plurality of rotor blades 15. The rotor can rotate together with the rotor blades 15 about a rotation axis 17. The rotor 13 and a generator connected to the rotor 13 are accommodated in a drop-shaped housing 19. The housing 19 is rotatably connected to a diffuser 21.

The diffuser 21 encloses the housing 19 rotationally symmetrical to form a flow channel through which the wind flows past the rotor blades 15 at a higher speed than without the diffuser 21. At the diffuser 21, a wind inlet opening 23 and a wind outlet opening 25 are provided , The wind flows through the diffuser from left to right. The diffuser 21 has a first inner diameter 27, which is located at the wind inlet opening 23. At the wind outlet 25, the diffuser 21 has a second inner diameter 29. A third diameter 31, which is located inside the diffuser 21, is the smallest, whereby a constriction 33 is formed in the diffuser 21. At this constriction 33, the rotor blades 15 are positioned. The first inner diameter 27 is preferably smaller than the second inner diameter 29.

The cross-section of the diffuser 21 is aerodynamically optimized so that the wind passing through the diffuser 21 achieves the highest possible speed. As a result, the energy yield of the wind power plant 11 according to the invention can be increased. In the following, the shape of the cross section of the diffuser 21 will be described in detail, which leads to the fluidic optimizations.

The diffuser 21 has an inner side 35, which forms the flow channel and the rotor 13 faces. The outer side 37 of the diffuser 21 faces away from the rotor 13. Both the inner side 35 and the outer side 37 are curved inwards in the direction of the rotor 13. However, the curvature of the inner side 35 is more curved than the curvature of the outer side 37. As a result, the diffuser 21 in the longitudinal cross-section has the shape of two opposing symmetrical airfoil profiles. At the wind inlet opening 23, a front edge 39 is formed at the transition from the inside 35 to the outside 37. At the wind outlet 25, a trailing edge 41 is formed at the transition from the inside 35 to the outside 37.

To form the shape of a wing profile, the five following angles are defined. A first angle is formed between the horizontal and the connecting straight line between the constriction 33 and the trailing edge 41. This first angle is between 7 and 21 degrees, preferably between 10 and 18 degrees, and more preferably between 13 and 15 degrees. A second angle 45 is formed between the horizontal and the connecting straight line between the constriction 33 and the leading edge 39. The second angle is between 10 and 40 degrees, preferably between 15 and 30 degrees, and more preferably between 17 and 21 degrees. A third angle 47 is formed between the horizontal and the tangent, which extends through the trailing edge 41 and rests against the outside 37 within the airfoil. This angle is preferably between 11 and 15 degrees and is between 1 and 3 degrees and preferably between 1.5 and 2 degrees smaller than the first angle 41. A fourth angle 49 is formed between the horizontal and the tangent, which is defined by the trailing edge 41 runs and rests on the outside 37 outside the wing profile. The fourth angle 49 is between 4 and 8 degrees and preferably between 5 and 7 degrees. The last fifth angle 51 defines the angle of attack, which is defined in the wing theory. The angle of attack is formed between the chord 53 and the horizontal. The chord 53 is the connecting line between the front edge 39 and the rear edge 41. In the present case, the angle of attack between 5 and 10 degrees and preferably between 7 and 8 degrees.

In order to optimize the air resistance, the leading edge 39 is rounded. The more curved inner side 35 than the outer side 37 and the constriction 33 formed lead to an increased flow velocity. According to flow theory, the flow velocity at the constriction 33 has a maximum. It is therefore particularly preferred for the wind yield when the rotor blades are positioned at the constriction 33. So that the flow at the outlet opening 25 does not rupture, the diffuser 21 is pointed and curved in the region of the outlet opening 25 to the outside. So that no turbulence occurs over the cross section of the flow channel, the housing 19 is formed drop-shaped.

Attached to the diffuser is a flow ring 55, which is also known in the anglicised jargon as "Fowler". The flow ring 55 corresponds in section to a flat angled profile with a first leg 57 and a second leg 59 (Figures 2 and 5). The first leg 57 extends substantially parallel to the outer rear edge of the diffuser 21 and overlaps therewith. Characterized an annular channel 61 is defined, wherein the kink 63 of the angled flow channel is located at a short distance to a plane defined by the outlet opening. The angle between the first and the second leg 57,59 is 130 degrees, wherein the angle could be 3 degrees larger or smaller, without significantly affecting the energy yield.

The generator housing 19 is connected to the diffuser 21 by means of three struts 65. The struts 65 are embedded in the diffuser body by means of welded plates 67, so that a stable construction is formed. The vertical strut 65 is supported on an arm 69, which is mounted with a rotary foot 71. It is important that the axis of rotation 73 is located substantially in the plane defined by the inlet opening 23 (corresponding to the diameter 27) or at a short distance to it outside the diffuser. It has been shown that this arrangement of the axis of rotation in conjunction with the flow ring prevents oscillation of the diffuser even at higher wind speeds.

Of importance is also the rotary foot 71. This has a flange 77 with through holes 79, which serve to receive mounting screws. By means of the flange 77, the rotary foot 71 can be mounted on a solid surface. Rotatably connected to the flange 77 is a cylindrical part 81, in which a sleeve 83 is received. In the sleeve 83, the electrical lines (not shown) are guided, which are in communication with the generator. In the jacket of the cylindrical part 81, an annular groove 85 is provided, which serves to receive a viscous liquid, preferably a highly viscous silicone oil. By means of a nipple 87 inserted into the housing wall 86, the viscous liquid can be filled into the annular space defined by the annular groove, so that it is completely filled with the liquid. In the annular groove 85 is optionally received a stopper 89 which is fixedly connected to the cylindrical part 81. Between the stopper 89 and the side walls of the annular groove 85, a gap 91 is present. Now acts a torque on the diffuser, the rotational movement is primarily braked because of the forces acting between the inner wall of the housing and the liquid shear forces. In addition, the stopper inhibits movement of the viscous fluid. The latter is partially pressed by the gap 91. This damping device has the advantage that the rotary arm with the diffuser is freely rotatable. It causes the diffuser to stand stable in the wind.

As liquids, as mentioned above, highly viscous silicone oils in question. Such has a kinematic viscosity of preferably at least 300 000 mm /, preferably of at least 400 000 mm / s and more preferably of at least 490 000 mm / s at 25 ° C (measured according to DIN 53 019).

The sealing of the annular groove 85 by means of seals 93, which are provided in grooves 95 in the outer diameter of the cylindrical portion 81. The housing 75 is supported on bearings 97 which are arranged on the flange 77 and on a shoulder 99 of the cylindrical part 81.

The reference numeral 101 sliding contacts are designated by means of which the electrical connections between the fixed lines inside the housing 75 and the recorded in the space 103 of the rotating arm 69 lines are made.

Legend 11 Wind energy plant 13 Rotor 15 Rotor blades 17 Rotation axis 19 Housing 21 Diffuser 23 Wind inlet opening 25 Wind outlet opening 27 First inner diameter 29 Second inner diameter 31 Third inner diameter 33 Constriction, constriction 35 Inner side of the diffuser 37 Outside of the diffuser 39 Front edge 41 Trailing edge 43 First angle 45 Second Angle 47 Third Angle 49 Fourth Angle 51 Fifth Angle 53 Tendon 55 Flow Ring (Fowler) 57 First Leg of Flow Ring 59 Second Leg of Flow Ring 61 Ring Channel 63 Kink 65 Stay 67 Plates 69 Arm 71 Rotary Foot 73 Rotary Axis 75 Housing 77 Flange

Claims (25)

79 through holes 81 cylindrical part 83 sleeve 85 annular groove 87 nipple 89 stopper 91 gap 93 seals 95 grooves 97 claims A wind turbine (11) comprising - a rotor (13) having a plurality of rotor blades (15) arranged to rotate freely about a rotation axis (17), - a generator in communication with the rotor (13) and a rotating rotor (13) converts the wind energy into electrical energy and - a diffuser (21) with - a wind inlet opening (23) and a wind outlet opening (25), which diffuser (21) the rotor (13) and the generator rotationally symmetrical encased and on which the generator is held in a rotationally fixed manner, the diffuser (21) having a constriction (33) at the location where the rotor blades (15) are positioned, an inlet region with one facing the rotor (13) and in the direction of the rotor (13) curved inside (35) - an outlet region with a rotor (13) facing away and in the direction of the rotor (13) curved outside senseite (37), wherein the diffuser (21) at the inlet opening (23) has a front edge ( 39) between the inside (35) and the outside (37) and at the outlet opening (25) forms a trailing edge (41) between the inside (35) and the outside (37), characterized in that at the rear edge of the diffuser (21) an angled flow ring (55) is placed, wherein an air channel (61) is formed between a first leg (57) of the flow ring and the outside. 2. Wind turbine according to claim 1, characterized in that the angle between the first (57) and the second leg (59) between 110 and 150 degrees, preferably between 120 and 140 degrees, and more preferably between 124 and 136 degrees. 3. Wind turbine according to claim 1 or 2, characterized in that the inner side (35) is curved more in the direction of the rotor (13) than the outer side (37). 4. Wind turbine according to one of the preceding claims, characterized in that the inner diameter (27) of the inlet opening (23) is smaller than the inner diameter (29) of the outlet opening (25). 5. Wind turbine according to one of the preceding claims, characterized in that the diffuser (21) in the longitudinal cross section has the shape of two opposing symmetrical airfoil profiles, wherein the more curved sides of the airfoils are facing each other. 6. Wind turbine according to claim 5, characterized in that at the airfoil profile of the angle (43) between the straight line connecting the constriction (33) and the trailing edge (41) and the horizontal between 7 and 21 degrees, preferably between 10 and 18 degrees and more preferably between 13 and 15 degrees. 7. Wind turbine according to one of claims 5 to 6, characterized in that at the airfoil profile of the angle (45) between the straight line connecting the constriction (33) and the front edge (39) and the horizontal between 10 and 40 degrees, preferably between 15 and 30 degrees, and more preferably between 17 and 21 degrees. 8. Wind turbine according to one of claims 5 to 7, characterized in that the angle (47) between the tangent which extends through the trailing edge (41) and on the outer side (37) rests within the airfoil, and the horizontal between 1 and 3 degrees, and preferably between 1.5 and 2 degrees, is smaller than the angle claimed in claim 6. 9. Wind energy plant according to one of claims 5 to 8, characterized in that the angle (49) between the tangent, which extends through the trailing edge (41) and on the outside (37) outside the airfoil profile, and the horizontal between 4 and 8 degrees and preferably between 5 and 7 degrees. 10. Wind turbine according to one of claims 5 to 9, characterized in that the angle of attack (51) between the chord (53) and the horizontal between 5 and 10 degrees and preferably between 7 and 8 degrees. 11. Wind turbine according to one of the preceding claims, characterized in that the front edge (39) is rounded. 12. Wind turbine according to one of the preceding claims, characterized in that the diffuser (21) in the flow direction is free of an undercut. 13. Wind energy plant according to one of the preceding claims, characterized in that the generator is connected by means of struts with the diffuser. 14. Wind turbine according to claim 13, characterized in that the struts are fixed to plates which are embedded in the diffuser body. 15. Wind energy plant according to one of the preceding claims, characterized in that the diffuser is arranged on a rotary foot (71). 16. Wind turbine according to claim 15, characterized in that the axis of rotation (73) of the rotary foot (71) approximately in the plane of the inlet opening (23) or seen in the flow direction at a small distance in front of this. 17. Wind energy plant according to one of claims 14 to 16, characterized in that the diffuser is arranged on an arm (69). 18. Wind energy plant according to one of claims 1 to 16, characterized in that in the rotary foot (71) is provided a damping device for damping the rotational movement of the diffuser (21). 19. Wind energy plant according to claim 18, characterized in that the damping device is based on the displacement principle. 20. Wind turbine according to claim 18 or 19, characterized in that in the rotary foot between a fixed, cylindrical part 81 and the arm (69) rotatably connected housing an annular channel (85) is provided for receiving a liquid. 21. Wind energy plant according to one of claims 18 to 20, characterized in that in the annular channel (85) a stopper is arranged. 22. Wind turbine according to claim 21, characterized in that between the stopper (89) and the side walls of the annular channel, a gap is present. 23. Wind energy plant (11) with - a rotor (13) with a plurality of rotor blades (15) which is arranged to rotate freely about a rotation axis (17), - a generator which is in communication with the rotor (13) and the rotor is rotating (13) converts the wind energy into electrical energy and - a diffuser (21) with - a wind inlet opening (23) and a wind outlet opening (25), which diffuser (21) the rotor (13) and the generator rotationally symmetrical encased and on which the generator is held in a rotationally fixed manner, and - an arm (69) on which the diffuser is arranged, which in turn is arranged on a rotary foot (71), characterized in that in the rotary foot (71) there is a damping device for damping the rotational movement of the diffuser ( 21) is provided. 24. Wind energy plant according to claim 21, characterized in that in the rotary foot (71) between a fixed, cylindrical part 81 and the arm (69) rotatably connected housing an annular channel (85) is provided for receiving a liquid, wherein between a with the housing firmly connected and received in the annular channel (85) stopper (89) and the annular channel, a gap is present. 25. Diffuser (21) for sheathing the rotor (13) of a wind turbine (11) with the diffuser features of the preceding claims.