GB2587575A

GB2587575A - A wind turbine

Info

Publication number: GB2587575A
Application number: GB2020134.9A
Authority: GB
Inventors: Collins David
Original assignee: Market Catalyst Ltd
Current assignee: Market Catalyst Ltd
Priority date: 2020-12-18
Filing date: 2020-12-18
Publication date: 2021-03-31
Anticipated expiration: 2040-12-18
Also published as: WO2022130244A1; GB202020134D0; GB2587575B

Abstract

A wind turbine of the cylindrical type which comprises a stator 2 surrounding a rotor 3. The stator includes a plurality of fixed vanes 30 which extend between first and second peripheral supports 10, 20. The rotor extends between first and second aerofoils 50, 52 and includes a number of rotor wings where the number of rotor wings is different from the number of fixed vanes. The N fixed vanes and the M rotor wings extend parallel to a rotational axis of the wind turbine. The first and second peripheral supports each have a fixed deflector 12, 22 which connects to a centre support located on the rotational axis.

Description

A WIND TURBINE

FIELD OF INVENTION

The present invention relates to a wind turbine.

BACKGROUND

Wind turbines are used to convert the kinetic energy of wind into electric power.

There are several forms of wind turbine available and it is advantageous to select the wind turbine configuration based upon a variety of criteria. For example, limitations on the configuration may be imposed by the operating environment -which can vary between extremes such as an offshore location and an urban environment. In some environments spatial constraints may be important whilst in others noise or visual impact may be of greater concern In order for a wind turbine to operate optimally it may also be necessary to consider the expected operating conditions -for example, the range and variability in wind speed and direction and the turbulence of the air (for example due to surrounding buildings or other obstructions).

Wind turbines may be broadly classified based upon the rotational axis of their blades (or equivalent elements) as either a Horizontal Axis Wind Turbine or a Vertical Axis Wind Turbine Larger installations are typically Horizontal Axis Wind Turbines as they are commonly suitable for generating high torque. A potential limitation of Horizontal Axis Wind Turbines is that they generally require that the rotor be aligned with the wind direction (and therefore require some form of alignment mechanism). As such, Vertical Axis Wind Turbines can be advantageous, particularly in sites with variable wind direction as they may be able to operate with wind from any direction. Further due to the alignment of the rotational axis with the support Vertical Axis Wind Turbines may benefit from enabling components such as generators and gearboxes to be ground mounted.

However, existing Vertical Axis Wind Turbines can encounter disadvantages including, for example: reduced rotational efficiency (since only some blades are being acted upon by the wind during rotation); increased wear and maintenance (for example as a result of vibrations or bending) lower overall operating efficiency; dynamic stability problems; and starting torque being such that some designs cannot self-start.

PRIOR ART

An example of a vertical axis wind turbine is described in UK Patent GB-B-2 199 377 (Mewburn-Crook Company Limited) wherein the vertical axis wind generator incorporates a circular turbine supported by an uppermost part of an upstanding support. A stator surrounds and is coaxial with the turbine and comprises an upper annular body positioned adjacent and or above the upper end of the turbine and has an uppermost surface which over at least a part of its radial width is inclined downwardly towards the vertical axis. A lower annular body is positioned adjacent and/or below the lower end of the turbine. Extending lengthwise between the annular bodies is a plurality of circumferentially spaced blades which define the venturi. The wind energy convertor converts wind energy from any direction into rotational kinetic energy.

Thus, it may be appreciated that there is a need for improved or alternative wind turbine designs which address or ameliorate at least some of the disadvantages of existing wind turbines. Embodiments of the present disclosure seek to provide a wind turbine which may provide advantages in at least some operating conditions and, therefore, provide an alternate option for the wind turbine installer.

SUMMARY OF INVENTION

According to a first aspect of the invention, there is provided a wind turbine comprising a stator which surrounds a rotor. The stator includes a plurality of (N) fixed vanes extending between first and second peripheral supports. The rotor extends between first and second aerofoils and includes a plurality (M) of rotor wings. The N fixed vanes and the M rotor wings extend parallel to a rotational axis of the wind turbine. The first and second peripheral supports each have a fixed deflector which connects to a centre support located on the rotational axis.

The first peripheral support may be an aerofoil. Additionally or alternatively, the second peripheral support may an aerofoil.

In some embodiments the first peripheral support may be in the form of a first annulus. Additionally or alternatively, the second peripheral support is in the form of is a second annulus According to some embodiments the (N) fixed vanes extending between the first and the second peripheral supports may be equi-spaced around the first and second peripheral supports. For example, the vanes may be circumferentially equispaced around the rotational axis of the wind turbine. The vanes may be equi-spaced around the annuli.

At least one peripheral support, for example the at least one annulus, may be orthogonal to the rotational axis of the wind turbine. In some embodiments both annuli may be orthogonal to the rotational axis of the wind turbine.

In some embodiments the number of fixed vanes (N) does not equal the number of rotor wings (M) For example the number of vanes (N) may be greater than the number of rotor wings (M).

In an embodiment there are 8 fixed vanes extending between first and second peripheral supports.

In some embodiments a fixed deflector may connect the first peripheral support to the centre support and may comprise a plurality of a first type of aerofoil. In some embodiments the fixed deflector that connects the second peripheral support to the centre support may comprise a plurality of a second type of aerofoil Either or both of the first type and/or the second type of aerofoils may have a variable pitch.

In a preferred embodiment there are 6 rotor wings.

In some embodiments the centre support is free to displace along its axis. For example, the centre support may be displaced by lift generated upon rotation The movement of the centre support may for example reduce frictions on a support is bearing.

Whilst the invention has been described above, it extends to any inventive combination of the features set out above or in the following description or drawings.

DESCRIPTION OF THE DRAWINGS

zo Embodiments of the invention may be performed in various ways, and an embodiment thereof will now be described by way of example only, reference being made to the accompanying drawing, in which: Figure 1 is a three-dimensional view of a wind turbine assembly in accordance with an embodiment; Figure 2 is a partial cross section through the rotational axis of the wind turbine of figure 1; Figure 3 is a top view of the wind turbine assembly of figure 1 showing the wind direction and resulting rotation; Figure 4 is a cross section orthogonal to the rotational axis and showing the airflow through the wind turbine; Figure 5 is a partial cross section through the rotational axis showing the 113 airflow through the wind turbine; and Figure 6 is an illustration of an airflow simulation showing the flow through the wind turbine assembly in use.

DETAILED DESCRIPTION OF EMBODIMENTS

As seen in figure 1, a wind turbine assembly 1 according to the present disclosure comprises a stator 2 which surrounds a rotor 3. The stator 2 is fixed relative to a mount in use and the rotor 3 is rotatable about its axis by the wind to provide power generation As such, the turbine assembly 1 is generally of a Vertical Axis Wind Turbine type construction such that it has a rotational axis (RA) extending through its centre. It will be appreciated that references to directions such as circumferential, radial or axial used in the following description are generally relative to the rotational axis.

However, such terms may be used broadly for descriptive purposes and are not limiting (for example the "axial" direction may be considered to be generally parallel to the rotational axis). In use, it will be appreciated that the rotational axis will typically be vertically aligned when the wind turbine is installed. Any directional references herein will be understood to be generally made with reference to this "in use" orientation of the turbine but are not intended to be strictly limiting since the device may take any orientation It will also be noted that references to circumferential and other such directions do not limit embodiments to having a strictly circular or regular form.

The stator 2 comprises first and second axially spaced apart peripheral supports 10, 20. Each peripheral support 10, 20 is orthogonal to the rotational axis (RA) of the wind turbine 1. The stator 2 also includes eight fixed vanes 30. Each fixed vane 30 113 extends axially (parallel to the rotational axis) between the peripheral supports 10, 20. The vanes 30 are equi-spaced around the circumference of the stator 2. As best seen in the cross section of figure 4, the vanes 30 are each aligned at an angle of incidence relative to the radial direction (the effect of which is described further below).

Each peripheral support 10, 20 has an annular body 11, 21. Within the inner opening of each annular body 11, 21 there is provided a respective deflector 12, 22. The deflectors 12, 22 provide a connection between the peripheral support annular body 11, 21 and a central support 40 which is located at the rotational axis (RA). The deflectors 12, 22 are rotationally fixed. In the illustrated embodiment, each deflector 12, 22 comprises three radially extending aerofoils, providing a spoked arrangement between the central support 40 and the annulus 11, 21 of the peripheral support 10, 20. The type/profile of the aerofoil selected for the first deflector 12 and/or the second deflector 22 may be selected to optimise flow characteristics through the wind turbine 1. In some embodiments the first deflector 12 and second deflector 22 may have different aerofoil profiles. Either or both of the deflectors 12 and 22 may further include a variable pitch mechanism for adjusting the pitch of the deflectors during use. For example, the pitch of one or both deflectors could be adjusted in response to factors such as wind speed and/or rotor rotational speed so as to optimise the flow through the wind turbine 1.

The rotor 3 is positioned within the stator 2 and is, therefore, best seen in the cross-sectional views of figures 2 and 4. The rotor includes first and second axially spaced apart aerofoils 50 and 52. The aerofoils 50 and 52 are generally orthogonal to the rotational axis RA of the wind turbine 1. Each aerofoil 50, 52 is arranged as a rotor of six radially extending blades (best seen in Figure 4) which extend from a 113 central hub 42. The central hub includes a central axle 44 extending along the rotatory axis RA of the turbine 1 and connecting the upper and lower aerofoils 50, 52.

At the radially outer ends of the rotor 3, an array of six rotor wings 60 extend axially between the aerofoils 50 and 52. As such the longitudinal direction of the wings 60 is generally parallel to the rotational axis RA of the wind turbine 1. Each rotor wing is positioned with a generally tangential alignment relative to the circumference of the rotor 3 and has an aerofoil cross sectional profile.

The operation of the wind turbine of the disclosed embodiment may be better appreciated from figures 3 to 6. As shown in the plan view of figure 3, the wind strikes the wind turbine from a direction which is generally perpendicular to the rotational axis. The wind turbine 1 does not need to be aligned to face the wind and can operate with the wind direction from any radial direction. With the wind direction shown from the left in this figure the resulting rotation for the rotor 3 relative to the stator 2 is in an anti-clockwise motion. As shown in Figure 4, the motion of the rotor 3 is a result of the interaction of the wind with the turbine as shown by the streamline arrows. It may be noted that the spacing of the streamline arrows provides an indication of the dynamic pressure (i.e. areas with a larger number of arrows are higher pressure and less arrows equate to lower pressure). The incoming wind is guided by the stator 2 to pass between the peripheral supports 10 and 20 and directed by the inclined orientation of the fixed vanes 30 to result in flow across the rotor 3 having a significant tangential velocity flow component. This flow causes the wind to pass over the rotor wings 30 of the rotor 3. A pressure differential is generated on each rotor wing 60 and causes a resulting propulsive lift force on the rotor wing 60. This propulsive force results in rotation of the rotor 3 which can then be used to drive a shaft connected to the hub 42 and axle 44 which can be used to drive an electrical generator.

As seen in the cross section of figure 5 and the fluid flow model of figure 6, the deflectors 12, 22 of the stator 2 and the aerofoils 50, 52 of the rotor also interact with the flow passing through the turbine 1. The axial openings provide an outlet for airflow from the rotor after it has acted upon the rotor wings 30. Such a flow may, for example, prevent such flow otherwise providing an unsteady effect on the flow through and around the rotor (for example the outlet flow can avoid passing through/over the downstream rotating rotor wings 30). Additionally, the aerofoils 50, 52 can be configured to provide a lift force in the vertical direction which acts to raise the rotor 3 when in operation. By providing the rotor with a degree of freedom of movement in the vertical direction (i.e. along its rotational axis) this lift force may enable the load and friction on supporting bearings to be reduced.

Although the invention has been described above with reference to preferred embodiments, it will be appreciated that various changes or modification may be made without departing from the scope of the invention as defined in the appended claims.

Claims

CLAIMS1. A wind turbine comprises a stator which surrounds a rotor, the stator includes a plurality of (N) fixed vanes extending between first and second peripheral supports, the rotor extends between first and second aerofoils and includes a plurality (M) of rotor wings, the N fixed vanes and the M rotor wings extend parallel to a rotational axis of the wind turbine; and the first and second peripheral supports each have a fixed deflector which connects to a centre support located on the rotational axis.
2. A wind turbine according to claim 1 wherein the first peripheral support is an aerofoil.
3. A wind turbine according to claim 1 or 2 wherein the second peripheral support is an aerofoil.
4. A wind turbine according to any preceding claim wherein the first peripheral support is in the form of a first annulus.
5. A wind turbine according to any preceding claim wherein the second peripheral support is in the form of a second annulus.
6. A wind turbine according to either claim 4 or 5 wherein the (N) fixed vanes extending between the first and the second peripheral supports are equi-spaced around the first and second annuli.
7. A wind turbine according to any of claims 4 to 6 wherein at least one annulus is orthogonal to the rotational axis of the wind turbine.
8. A wind turbine according to claim 7 wherein both annuli are orthogonal to the rotational axis of the wind turbine.
9. A wind turbine according to any preceding claim wherein N#M.
10. A wind turbine according to any preceding claim wherein there are eight fixed vanes extending between first and second peripheral supports.
11. A wind turbine according to any preceding claim wherein the fixed deflector that connects the first peripheral support to the centre support comprises a plurality of a first type of aerofoil.
12. A wind turbine according to any preceding claim wherein the fixed deflector that connects the second peripheral support to the centre support comprises a plurality of a second type of aerofoil.
113 13. A wind turbine according to either claim 11 or 12 wherein the first type and/or the second type of aerofoils have a variable pitch.
14. A wind turbine according to any preceding claim wherein there are six rotor wings.
15. A wind turbine according to any preceding claim wherein the centre support is free to displace along its axis by lift generated upon rotation (so as to reduce frictions on a support bearing).