EP3052801A1

EP3052801A1 - Rotor for a vertical-axis wind turbine

Info

Publication number: EP3052801A1
Application number: EP14793881.5A
Authority: EP
Inventors: Rainer MÖLLER; Sylvain ADAMS; Stéphane RAQUIN
Original assignee: Electricfil Automotive SAS
Current assignee: EFI Automotive SA
Priority date: 2013-09-30
Filing date: 2014-09-29
Publication date: 2016-08-10
Also published as: FR3011285A1; WO2015044615A1; FR3011285B1

Abstract

The invention concerns a rotor for a vertical-axis wind turbine comprising a support structure (6) for a series of blades (7) distributed at the periphery of the structure and each comprising a wing (13) having a leading edge (14) linked to a trailing edge (15) by a body (16) delimiting an outer face (17) and an inner face (18), and a baffle (21) extending separated from the leading edge of the wing and facing the inner face (18) of the wing (13) over a limited length in order to delimit, with the wing (13), an air inlet corridor (25). According to the invention, for each blade, the baffle (21) has an outer edge (22) located in the extension of the chord line to delimit the inlet of the air inlet corridor (25), the baffle extending facing the inner face (18) of the wing in order to delimit, with the wing, an air inlet corridor (25) of which the width decreases from the leading edge (14) towards the trailing edge (15).

Description

ROTOR FOR VERTICAL AXIS WINDMILL

The present invention relates to the technical field of apparatus for capturing the energy of a fluid in motion, and it is particularly aimed at wind turbines capable of transforming wind energy into mechanical or electrical energy.

According to the preferred application, the object of the invention relates to a wind turbine with a vertical or substantially vertical axis of rotation.

Vertical-axis wind turbines have a number of advantages over horizontal-axis wind turbines, such as the lack of a mechanism to direct them in the direction of the wind, correct operation even with a rapidly changing wind. orientation, and a static positioning of the electric generator facilitating the electrical connection.

In the field of vertical axis wind turbines, it is known wind turbines exploiting mainly differential drag, such as Savonius type wind turbines. This type of wind turbine has a simple design, working well with turbulent winds and usually starting alone, but has a low efficiency.

It is also known Darrieus type wind turbines that mainly exploit the lift. This type of wind turbine makes it possible to obtain higher yields than Savonius-type wind turbines, but has the disadvantage of having difficulty starting alone or without assistance.

For example, the patent application FR 2 567 588 describes a vertical axis wind turbine to eliminate the use of the auxiliary start-up system while increasing the yield. The wind turbine described by this document comprises a support structure for blades in the form of a vertical axis of rotation radially equipped with arms at the end of which are fixed blades. Each blade comprises on the one hand, a wing having a leading edge connected to a trailing edge by a body delimiting an outer face and an inner face and, on the other hand, a deflector extending away from the edge of the blade. wing attack. This wind turbine has poor performance and is not designed to start alone. Patent application WO 2010/125599 also describes a wind turbine having a series of blades mounted at the end of arms extending radially from a rotatably driven shaft. Each blade comprises on the one hand, a wing and on the other hand a deflector extending facing the inner face of the wing and in a profile identical to the inner face of the wing in order to delimit a corridor of width constant. This wind turbine is designed to allow the self-starting of the rotor even in case of wind at low speed. However, this wind turbine does not have a good performance and can not start in practice with a low wind speed,

It is known from the documents WO 2005/040559 and CN 102661239 to make each blade of a rotor or stator by at least one first fin whose inner face extends in relation with the external face of a second fin to delimit a corridor of decreasing section from the leading edges of the fins. This type of design is particularly advantageous for applications to fans or turbines, but no advantages appear for wind turbines. In a complementary manner, the characteristics of realization of the blades described by these documents, even applied to wind turbines, do not allow to obtain a good performance and a start with a low wind speed.

The object of the invention is therefore to overcome the drawbacks of prior technical solutions by proposing a new wind turbine rotor designed to allow starting without the need for an assistance or auxiliary system, even in case of low speed winds, any by achieving a high yield.

The invention thus relates to a rotor for vertical axis wind turbine having a support structure of a series of blades distributed at the periphery of the structure and each comprising on the one hand, a wing having a leading edge connected to an edge. by a body delimiting an outer face and an inner face and on the other hand, a deflector extending away from the leading edge of the wing and vis-à-vis the inner face of the wing on a limited length to delimit with the wing, an air inlet corridor. According to the invention, for each blade, the deflector has an edge external located in the extension of the rope sign to delimit the entrance of the air inlet corridor, the deflector extending vis-à-vis the inner face of the wing to delimit with the wing, an air inlet corridor whose width decreases from the leading edge towards the trailing edge.

The rotor according to the invention further comprises, in combination, one and / or the other of the following additional characteristics:

for each blade, the air inlet corridor decreases progressively,

for each blade, the air inlet corridor decreases by between 30 and 50% between its inlet and its outlet, delimited respectively by the external and internal edges of the deflector,

- for each blade, the maximum width of the entrance lane is equal to a value between 10 and 20% of the length of the chord line of the wing,

at least a part of the outer face of the wings extends in a circle from which the outer edges of the deflectors are located,

- For each wing, the leading edge has a convex profile connecting the inner and outer faces between them and the inner and outer faces have different profiles such that the line of camber of the wing has from the leading edge , an arrow towards the internal face, and from the trailing edge, an arrow towards the external face,

- for each blade, the arrow of the line of camber of the wing towards the internal face, has a value between 0,5% and 2% of the length of the line of cord of the wing while the arrow of the line of camber from the wing to the outer face has a value between 3 and 5% of the length of the wing line of the wing,

for each blade, the wing possesses, from the leading edge, inner and outer faces of curved profile, and from the curved profile, a profile narrowing to the trailing edge,

- for each blade, the maximum thickness presented by the wing is equal to a value between 20 and 30% of the length of the wing line of the wing, - the sum of the lengths of the rope line of the blade wings is equal to a value between 0.45 and 0.55 times the circumference of the circle passing through the outer surfaces of the wings,

the support structure of the blades comprises a disc and a ring between which the blades are mounted, the ring leaving in its center an opening for the air,

the rotor is equipped with a generator with permanent magnets,

the rotor comprises an even number of blades,

the disk is provided at its periphery with a protective skirt extending in the opposite direction of the blades.

Another object of the invention relates to a wind turbine equipped with a rotor according to the invention and with a vertical axis comprising a stator equipped with a rotation guide system for the rotor.

Various other characteristics appear from the description given below with reference to the accompanying drawings which show, by way of non-limiting examples, embodiments of the subject of the invention.

Figure 1 is an elevational sectional view of a wind turbine according to the invention.

Figure 2 is a perspective view of an exemplary embodiment of a rotor according to the invention for a wind turbine illustrated in Fîg. 1.

Figure 3 is a cross sectional view of the rotor according to the invention, showing the relative arrangement of the blades.

Figure 4 is a view showing the profile of a wing according to the invention.

As is apparent from the Figures, the subject of the invention relates to a wind turbine 1 comprising a stator 2, equipped with a rotation guide system 3, for a rotor 4 along an axis of rotation X. The rotor 4 rotates around the axis of rotation X in a direction of movement, shown in FIG. 3, by the arrow f (Fig. 3).

According to a preferred application, the wind turbine 1 is mounted so that the axis of rotation X of the rotor 4 extends vertically or substantially vertically during its operation. It should be noted that the wind turbine 1 according to the invention can also be easily positioned in different positions with its axis of rotation which is perpendicular or substantially perpendicular to the direction of the fluid.

As is more particularly apparent from Figs. 1 and 2, the rotor 4 comprises a support structure 6 for a series of blades 7 distributed advantageously, in a regular manner, at the periphery of the support structure 6. In the embodiment illustrated in the drawings, the structure of FIG. support 6 comprises a lower disc 8 supporting one of the lower ends of the blades 7 and a crown 9 said upper fixed on the upper ends of the blades 7. Preferably, the ring 9 leaves in its center, an opening 11 for the passage air. The disk 8 is advantageously solid while being provided at its center with an axis 12 cooperating with the rotational guiding system 3.

Of course, the support structure 6 of the blades 7 can be made differently. For example, this support structure 6 may comprise an axis from which radially extend arms at the ends of which the blades 7 are fixed.

The blades 7 are mounted to extend parallel to each other and parallel to the axis of rotation X. In the example shown, the blades 7 are considered to extend vertically. Each blade 7 comprises a flange 13 having a leading edge 14 connected to a trailing edge 15 by a body 16 which delimits on one side, an outer face 17 and on the opposite side, an inner face 18 (FIG. . The faces 17 and 18 of the body 16 of the wing 13 are said external and internal in consideration of the inside and outside of the rotor 4. In a conventional manner, each wing 13 has a line of rope 19 corresponding to the line straight line between the end points of the leading edge 14 and the trailing edge 15 (Fig. 4). Similarly, each wing 13 has a camber line corresponding to the median line 20 between the outer 17 and inner 18 faces of the body 16.

The bodies 16 of the wings 17 thus extend continuously between the disk 8 and the ring 9 with the leading edges 14 and the trailing edges 15 which extend parallel to the axis of rotation X. more precisely in FIG. 3, the wings 13 are oriented so as to be contained entirely within a circle C passing through at least a portion of the outer faces 17 of the wings. The circle C thus corresponds to the maximum surface covered by the blades 7 during their rotation. Circle C is thus tangent on at least a portion of the outer faces of wings 13.

Each blade 7 also comprises a deflector 21 extending at a distance from the leading edge 14 of the eye 13. Each deflector 21 also extends continuously between the disc 8 and the crown 9. Each deflector 21 is delimited by an edge external 22 and the opposite, by an inner edge 23. The outer edges 22 and inner 23 taken into consideration from the inside and outside of the rotor extend parallel to each other and parallel to the axis of rotation X. The outer edges 22 of the baffles are advantageously located substantially at the circle C.

According to the invention, for each blade 7, the deflector 21 extends opposite the wing 13 over a limited length to delimit with this wing 13, an air inlet corridor 25 whose width 1 decreases leading edge 14 towards the trailing edge 15, the inlet corridor 25 and has an entrance delimited between the outer edge 22 of the deflector and the portion of the wing 13 in correspondence, namely the edge 14, and an output delimited between the inner edge 23 and the portion of the wing in correspondence, namely the inner face 18. It is clear from FIGS. 3 and 4, the deflector 21 is located inside the wing 13 placed vis-a-vis. As appears more specifically in FIG. 4, the outer edge 22 of the deflector 21 is advantageously located in the extension of the rope line 19.

Thus, for each blade 7, the associated deflector 21 extends from a point situated on the extension of the rope line 19 of the wing 13 and over a limited length, facing the inner face 18 of the wing, to delimit with it, the air inlet corridor 25 whose width decreases from the leading edge 14 and towards the trailing edge 15. According to an advantageous embodiment variant, the air inlet corridor 25 progressively decreases between its inlet and its outlet, that is to say that its width 1 progressively decreases from its inlet to its outlet.

Advantageously, for each blade 7, the air inlet corridor 25 decreases by a value between 30 and 50% between its inlet and its outlet.

It must therefore be considered that the distance between the deflector 21 and the wing 13 is reduced by going from the outside to the inside to accelerate the speed of the air passing in this direction. This fast airflow favors the attachment of the boundary layer. The distance between the deflector 21 and the wing 13 must be large enough to let a significant amount of air pass between the two and sufficiently small not to increase the drag of the wing 13. Advantageously, for each blade 7, the maximum width of the entry corridor 25 is equal to a value between 10 and 20% of the length of the rope line 19 of the wing 13.

According to an alternative embodiment illustrated in the drawings, for each blade 7, the leading edge 14 has a convex profile connecting the inner 18 and outer 17 faces between them.

The inner 18 and outer 17 faces have different profiles such that the line of camber 20 of the wing has from the leading edge 14, an arrow d towards the inner face 18 and from the trailing edge 15, a arrow d to the outer face 17. In other words, the wing 13 has a camber line 20 with a positive arrow for the portion 1a closer to the leading edge 14 (curved towards the inside of the rotor) while the camber line 20 has a negative arrow (bulging outwardly of the rotor), for the part located near the trailing edge 15. This arrangement makes it possible to obtain a good coefficient of torque in the direction of rotation of the wind.

According to an advantageous variant embodiment, for each blade 7, the arrow d of the camber line 20 of the wing has, towards the inner face 18, a value between 0.5 and 2% and for example a value equal to 1% of the length of the rope line 19 of the wing, while the arrow d of the camber line 20 of the wing towards the outer face 17 possesses a value between 3 and 5% of the length of the rope line 19 of the wing and for example a value equal to 4%. According to this embodiment, the wing has a not too high drag.

It should be noted that the outer face 17 of the wing follows, on a portion substantially the circle C of the rotor of the wind turbine and that the outer edge 22 of the deflector 21 is located approximately on this circle C, thus allowing to obtain a relatively weak drag for the movement of the wing against the direction of the wind.

As can be seen from the figures, for each blade 7, the wing 13 possesses, from the leading edge 14, inner and outer faces 17 and 17 of convex profile, and from the curved profile, a profile narrowing as far as 'at the trailing edge. Each wing 13 thus has a body 16 of three-dimensional shape. For each blade 7, the maximum thickness presented by the wing 13 is equal to a value between 20 and 30% of the length of the rope line 19 of the wing. Such dimensioning makes it possible to increase the maximum angle of incidence before stalling. According to an advantageous characteristic of embodiment, the sum of the lengths of the rope line 19 of the set of wings 13 of the rotor 4 is equal to a value between 0.45 and 0.55 times the circumference of the circle C passing through the outer faces 17 of the wings. Such a dimensioning makes it possible to overcome the friction torque even at very low wind speed. Such dimensioning makes it possible to provide a relatively large torque.

According to an advantageous embodiment, the rotor 4 comprises an even number of blades 7. Thus, each wing 13 which must move in the opposite direction to the wind, is counterbalanced by a wing of the same size and the same lever arm that moves in the direction of the wind. For example, it may be provided to make a rotor with four wings.

It follows from the foregoing description that the rotor according to the invention and in particular by virtue of the positioning of the deflector with respect to the wing and its shape relative to the wing, makes it possible to obtain a wind turbine with a good efficiency and can start even with a wind with a low speed. Advantageously, the rotor is equipped with a generator 31 with permanent magnets. According to an alternative embodiment illustrated more particularly in FIG. 1, the disk 8 is provided at its periphery with a protective skirt 30 extending in the opposite direction of the blades and making it possible to protect the permanent magnet generator 31, a part of which is mounted integral with the disk 8.

The invention is not limited to the examples described and shown because various modifications can be made without departing from its scope.

Claims

1 - Rotor for vertical axis wind turbine comprising a support structure (6) of a series of scales (7) distributed around the periphery of the structure and each comprising on the one hand, a wing (13) having an edge of stroke (14) connected to a trailing edge (15) by a body (16) defining an outer face (17) and an inner face (18) and, on the other hand, a deflector (21) extending at a distance from the leading edge of the wing and vis-à-vis the inner face (18) of the wing (13) over a limited length to delimit with the wing (13), an entry corridor of air (25), characterized in that for each blade, the deflector (21) has an outer edge (22) located in the extension of the rope line (19) to delimit the entrance of the air inlet corridor (25), the deflector extending opposite the inner face (18) of the wing to delimit with the wing, an air inlet corridor (25) whose width decreases the edge of attack (14) towards the edge of leaks e (15).

2 - Rotor for wind turbine according to claim 1, characterized in that for each blade (7), the air inlet corridor (25) decreases gradually.

3 - rotor for a wind turbine according to claim 1 or 2, characterized in that for each blade (7), the air inlet corridor (25) decreases by a value between 30 and 50% between its entry and its outlet respectively delimited by the outer and inner edges of the deflector (21).

4 - rotor for a wind turbine according to one of claims 1 to 3, characterized in that for each blade (7), the maximum width of the inlet corridor (25) is equal to a value between 10 and 20% of the length of the rope line (19) of the wing.

5 - rotor for a wind turbine according to one of claims 1 to 4, characterized in that at least a portion of the outer face (17) of the wings (13) extends in a circle (C) from which are located the outer edges (22) of the baffles (21).

6 - rotor for a wind turbine according to one of claims 1 to 5, characterized in that for each wing (13), the leading edge (14) has a convex profile connecting the inner face (18) and outer (17) between them and in that the inner (18) and outer (17) faces have different profiles such that the line of camber (20) of the wing has from the leading edge (14), an arrow (d) towards the inner face (18), and from the trailing edge, an arrow towards the outer face (17).

7 - rotor for a wind turbine according to claim 6, characterized in that for each pay (7), the arrow (d) of the line of camber (20) of the wing to the inner face (18) has a value included between 0.5% and 2% of the length of the rope line (19) of the wing while the arrow (d) of the line of camber (20) of the wing towards the outer face has a value of between between 3 and 5% of the length of the line of rope (19) of the wing.

8 - rotor for a wind turbine according to claim 6 or 7, characterized in that for each blade (7), the wing (13) has from the leading edge (14), inner (18) and outer faces ( 17) curved profile, and from the curved profile, a profile narrowing to the trailing edge (15).

9 - rotor for a wind turbine according to one of claims 6 to 8, characterized in that for each blade (7), the maximum thickness presented by the wing (13) is equal to a value between 20 and 30% of the length of the rope line (19) of the wing.

10 - Rotor for a wind turbine according to one of claims 1 to 9, characterized in that the sum of the lengths of the rope line (19) of the wings (13) of the blades (7) is equal to a value between 0, 45 and 0.55 times the circumference of the circle (C) passing through the outer surfaces of the wings.

11 - Rotor for a wind turbine according to one of claims 1 to 10, characterized in that the support structure of the blades (7) comprises a disc (8) and a ring (9) between which the blades (7) are mounted, the ring (9) leaving in its center an opening (11) for the air.

12 - Rotor for wind turbine according to one of claims l to 11, characterized in that it is equipped with a permanent magnet generator (31).

13 - Rotor for wind turbine according to one of claims 1 to 12, characterized in that it comprises an even number of blades (7). 14 - wind turbine rotor according to one of claims 11 to 13, characterized in that the disk (8) is provided at its periphery with a protective skirt (30) extending in the opposite direction of the blades (7).

15 - Vertical axis wind turbine characterized in that it comprises a stator (2) equipped with a rotation guide system (3) for the rotor (4) according to one of claims 1 to 15.