GB2269859A

GB2269859A - Vertical axis wind turbine.

Info

Publication number: GB2269859A
Application number: GB9300182A
Authority: GB
Inventors: Clive Murray Coker
Original assignee: Individual
Current assignee: Individual
Priority date: 1992-08-20
Filing date: 1993-01-06
Publication date: 1994-02-23
Also published as: GB9217698D0; GB9300182D0

Abstract

The wind turbine includes stator blades 1, rotor blades 2 and a domed, annular shroud 3 with a flared cone 4. The shroud surmounts the cone and the stator blades extend between the base of the shroud and a lower region of the cone, the shroud having upper and lower openings 3A, 3B. The rotor blades are mounted in the shroud for rotation about the central axis of the cone. <IMAGE>

Description

UPRIGHT AXIS WIND TURBINE This invention relates to an upright axis wind turbine.

A known upright or vertical axis wind turbine has been developed for wind energy conversion purposes and basically comprises a plurality of spaced, vertical stator blades mounted around an annular ring and surrounding a plurality of spaced, vertical rotor blades, which are arranged for rotation about a central pole on which the turbine is erected. Around the rotor and coaxial with it is an omnidirectional shroud consisting of a plurality of ducts surmounted by an annular dome. Wind flow is accelerated by continuity onto the rotor through a plurality of up-wind ducts and exits mainly through the top and bottom of the rotor. Wind flow over the dome reduces the exit pressure which not only increases the pressure differential across the turbine but also augments the mass flow rate through it.

The present invention has for an object further to increase the efficiency and to improve the construction of such a turbine.

According to the present invention, there is provided an upright axis wind turbine comprising spaced stator blades and rotor blades, a shroud and a central cone with its pinnacle uppermost in use, the shroud surmounting the cone and the stator blades extending between the base of the shroud and a lower region of said cone, said shroud having upper and lower openings and said rotor blades, forming the active surfaces of an axial or semi-axial turbine rotor, being mounted in the said shroud for rotation about the central axis of said cone.

The shroud may be annular with the rotor blades mounted in the annulus of the shroud.

The cone may be flared.

The stator blades can extend radially or non-radially of the cone.

Preferably, the rotor blades extend radially of the axis of the cone.

The rotor blades can be mounted on a central shaft extending into the cone and coupled to a drive mechanism.

The shroud may be domed and may be substantially triangular in cross-section with two of its sides being curved and the remaining, inner side flaring outwardly around the annulus.

For a better understanding of the invention and to show how the same may be carried into effect, reference will now be made, by way of example, to the accompanying drawings, in which Figure 1 is a diagrammatic perspective view of a wind turbine according to the invention, Figure 2 is a plan view of the turbine shown in Figure 1, Figure 3 is a cross-sectional side view taken on the line A-A of Figure 2, Figure 4 is a cross-sectional view taken on the line B-B of Figure 3, Figure 5 is a view similar to Figure 1 of a modified version of the wind turbine, Figure 6 is a plan view of the turbine shown in Figure 5, Figure 7 is a cross-sectional side view taken on the line A-A of Figure 6, Figure 8 is a cross-sectional view taken on the line B-B of Figure 7, Figure 9 is a view similar to Figure 7, showing a further possible modification of the turbine, and Figure 10 is a view similar to Figure 9 illustrating yet another possible modification.

Referring to Figures 1 to 4 of the drawings, the upright axis wind turbine includes eight spaced stator blades 1, six rotor blades 2, a domed, annular shroud 3 and a central, flared cone 4 having a truncated pinnacle 4A.

The annular shroud 3 is substantially triangular in crosssection with two of its sides (the outer upper and the outer lower) being slightly curved, whilst the remaining, inner side being flared outwardly around the annulus as best seen in Figure 3.

The stator blades 1 extend between the underside of the shroud 3 and the lower region of the central cone 4 in a non-radial fashion in order to optimise wind flow onto the cone 4 in a non-radial fashion to impart spin to the airflow before it passes upwards through the turbine rotor blades, thereby having the effect of increasing the power output generated.

The rotor blades 2 extend radially from a central axis 5 coincident with the central axis of the cone 4.

The shroud 3, being in the form of an annulus, and the domeshape being truncated, has upper and lower central openings 3A, 3B, respectively. The rotor blades 2 are mounted in the shroud in a lower region thereof, closely adjacent the tops of the stator blades 1. The rotor blades 2 are mounted on a rotatable shaft 6 which extends down through the truncated pinnacle of the cone 4, which can contain a gear train and an electrical generator, for example.

In use, the turbine is erected with the axis 5 vertical and substantially horizontal air flow will then strike the stator blades 1 and be directed inwardly towards the cone 4, which in turn directs the air flow upwards through the opening 3B of the shroud 3, the air flow thereby striking and causing the rotor blades 2 to rotate to drive the generator. Air is then expelled from, and drawn out of (see below), the opening 3A.

The effect is enhanced by the design of the shroud 3. The dome shape of the shroud 3 creates a region which itself acts as a stator, imparting spin to the air flow entering the turbine, thereby having the effect of increasing power output generated thereby. The dome shape of the shroud 3 creates a region of low pressure on the low pressure side of the turbine (in the region of the opening 3A), thereby increasing the power output.

It will be appreciated that since the air flow is concentrated through the turbine housing constituted by the shroud 3, the rotor blades of the turbine can also be compact. Since the rotor blades are shrouded, this should result in low noise levels in operation and the dangers of ice sheets being thrown out are reduced with the present construction as compared with known horizontal axis windmill type wind turbines. Shrouded axial rotor blades also have the advantage of having low aerodynamic tip losses due to vortex shedding compared with known, unshrouded wind turbines.

By mounting the turbine with the axis 5 vertical, this removes the need for steering systems to take account of changing wind direction.

The turbine is self starting and no moving parts are visible from the usual line of sight, thereby adding to visual acceptability.

The shroud 3 surmounts the stator blades 1 and is supported thereby and some of the blades 1 could be continued downwardly as supporting structural pillars resting on separate foundations, thereby facilitating the use of comparatively shallow foundations.

Speed control of the turbine can be achieved, for example, by providing variable-pitch rotor blades 2 and/or reducing the free area on the low pressure side of the turbine.

Figures 5 to 8 illustrate another form of turbine, in which a number of modifications have been made to the design illustrated in Figures 1 to 4. Like reference numerals indicate like parts.

The form illustrated in Figures 5 to 8 includes a non-flared central cone 4 and a shroud 3 which is not domed.

Furthermore, the stator blades 1 extend radially.

The stator blades 1, whether they extend radially or non-radially, can extend inwardly as far as the cone 4.

As illustrated in Figure 9, the shroud 3 is given a smoother profile in the form of a venturi shape.

In addition, Figure 9 illustrates an optional feature in the form of an outer ring 7 surrounding the upper opening of the shroud 3, which has the effect of causing turbulence and encouraging an upward flow of air to reduce the pressure at the exit of the turbine.

Figure 9 also illustrates another optional feature, in the form of a horizontal ring of curved vanes 8 surrounding the cone 4, these vanes 8 serving to encourage a smooth air flow into the turbine.

Figure 10 illustrates a form of turbine which is rather more squat in design, the shroud being given an extended "C" cross-section, which also assists in directing air into the entry of the turbine. It is envisaged that this design of turbine could be incorporated into the roof structure of a tall building.

In contrast, the form illustrated in Figure 9 illustrates an arrangement in which the building itself could form part of the central cone 4 and external structural elements extending down from the shroud 3 could be extensions of the vertical stator guide vanes 1 which extend inwards to meet the cone 4. It will be appreciated that any of the features described above can be used alone or in any combination as desired.

Claims

CLAIMS;

1. An upright axis wind turbine comprising spaced stator blades and rotor blades, a shroud and a central cone with its pinnacle uppermost in use, the shroud surmounting the cone and the stator blades extending between the base of the shroud and a lower region of said cone, said shroud having upper and lower openings and said rotor blades, forming the active surfaces of an axial or semi-axial turbine rotor, being mounted in the said shroud for rotation about the central axis of said cone.

2. A turbine according to claim 1, wherein said shroud is annular with the rotor blades mounted in the annulus of the shroud.

3. A turbine according to claim 1 or 2, wherein said cone is flared.

4. A turbine according to claim 1, 2 or 3, wherein said stator blades extend radially of said cone.

5. A turbine according to claim 1, 2 or 3, wherein said stator blades extend non-radially of said cone.

6. A turbine according to any one of the preceding claims, wherein said rotor blades extend radially of the axis of said cone.

7. A turbine according to any one of the preceding claims, wherein said rotor blades are mounted on a central shaft extending into said cone and coupled to a drive mechanism.

8. A-turbine according to any one of the preceding claims, wherein said shroud is domed.

9. A turbine according to any one of the preceding claims, wherein said shroud is substantially triangular in cross-section with two of its sides being curved and the remaining, inner side flaring outwardly around the annulus.

10. A turbine according to any one of the preceding claims, wherein said shroud is supported by said stator blades, some of which being continued away from the shroud to rest on separate foundations, thereby acting as supporting structural pillars for said shroud.

11. A turbine according to any one of the preceding claims and further comprising speed control means.

12. A turbine according to any one of the preceding claims, wherein a ring surrounds and is spaced from the upper opening of the shroud thereby to encourage an upward flow of air to reduce pressure at the exit of the turbine.

13. A turbine according to any one of the preceding claims, wherein a ring of curved vanes surrounds the cone, these vanes serving to encourage a smooth air flow into the turbine.

14. A turbine according to any one of the preceding claims, wherein said shroud has an extended "C" cross-section to assist in directing air into the entry of the turbine.

15. A turbine according to any one of the preceding claims, wherein said cone forms part of a building.

16. An upright axis wind turbine, substantially as hereinbefore described with reference to any one of the embodiments shown in the accompanying drawings.