GB2175350A

GB2175350A - Wind-driven aerodynamic devices

Info

Publication number: GB2175350A
Application number: GB08607345A
Authority: GB
Inventors: Derek Alan Taylor
Original assignee: Open University
Current assignee: Open University
Priority date: 1985-03-27
Filing date: 1986-03-25
Publication date: 1986-11-26
Also published as: GB8607345D0; GB8507995D0

Abstract

A vertical axis wind turbine has two upwardly inclined blades (10) carried by a support tower (12) below the blades which is short in relation to the length of the blades and supporting the blades for rotation about a vertical axis. Bracing wires, cables or the like (16) extend either from the blades (10) to a central post (30) or directly from blade to blade. To give the turbine a wide hub the blades (10) preferably extend upwards from the ends of horizontal arms (32) adjacent to the top of the tower (12). A large number of blade configuration and mounting arrangements are disclosed including arrangements in which the blades are vertically orientated. <IMAGE>

Description

SPECIFICATION Aerodynamic devices This invention relates generally to aerodynamic devices functioning on a turbine principle where the device is subject to the action of a moving fluid.

Our UK patent specification 2102079B describes various forms of vertical axis wind turbine.

The vertical axis wind turbine claimed in the aforesaid patent specification comprises a support tower, one or more blades mounted in cantilever manner on a pivot hub at the top of the support tower, the or each blade being without support above the level of the pivot hub and having a blade arm extending freely upwards in an inclined manner from the pivot hub, mounting means supporting the or each blade so that it is both rotatable about the vertical axis of the support tower to sweep out a generally conical volume above the tower and also simultaneously pivotable about a horizontal axis passing through said vertical axis such that with increasing wind speed the inclination of the longitudinal axis of the blade arm to said vertical axis of the support tower wiil increase, said mounting means allowing changes in the inclination of the blade arm or arms under the action of centrifugal forces, and resilient bias means acting on the or each arm in opposition to the centrifugal forces to control the inclination of the blade or blades in dependence on changes in wind speed.

In a preferred embodiment of that vertical axis wind turbine, the turbine comprises a blade having a long arm projecting upwardly from the hub and a relatively short, counterbalanced arm extending below the level of the hub.

It is an object of the present invention to provide an aerodynamic device which may be regarded as a modification of or development from the wind turbines shown in the aforesaid patent specification.

In accordance with one aspect of the present invention there is provided an aerodynamic device comprising a pair of upwardly inclined blades, a support tower below the blades which is short in relation to the length of the blades supporting the blades for rotation about a vertical axis, and bracing means extending directly from blade to blade.

In accordance with another aspect of the invention there is provided an aerodynamic device comprising one or more upwardly inclined blades, a support tower below the blade or blades which is short in relation to the length of the blade or blades supporting the blade or blades for rotation about a vertical axis, and bracing means extending from the or each blade to a central post on said axis.

Preferably, the device is given a wide hub at the top of the tower by having the blades extending upwards from horizontally extending support arms.

The bracing means may comprise one or more thin wires, cables or rods.

The blade or blades can be fixed in a particular inclined position, or may be adjustable whilst stationary, or may be adjustable while spinning. In the latter case the bracing means are extendable.

The blades are preferably of aerofoil cross section. They can be of fixed or variable pitch and may be provided with variable pitch outer portions, preferably at the tips.

In order that the invention may be more fully understood, a number of embodiments of device in accordance with the invention will now be described by way of example and with reference to the accompanying drawings.

In the drawings: Figs. 1a to 1d show a first embodiment of vertical axis wind turbine in accordance with the invention; Fig. 2 shows a second embodiment of vertical axis wind turbine in accordance with the invention; Fig. 3 shows a third embodiment of vertical axis wind turbine in accordance with the invention; Fig. 4 shows a fourth embodiment of vertical axis wind turbine in accordance with the invention; Fig. 5 shows a single blade wind turbine in accordance with the invention; Fig. 6 shows a further embodiment of wind turbine in accordance with the invention; Fig. 7 shows the wind turbine of Fig. 6 in an alternative disposition; Fig. 8 shows a further wind turbine, similar to that of Figs. 6 and 7; Fig. 9 shows another embodiment of single blade wind turbine in accordance with the invention; Fig. 10 shows a fixed geometry wind turbine similar to Fig. 9;; Fig. 11 shows yet another embodiment of 2-blade wind turbine in accordance with the invention; Figs. 1 2a to 1 2d show a further embodiment of wind turbine in accordance with the invention; Fig. 13 shows another wind turbine in accordance with the invention with an extended hub; Fig. 14 shows a further wind turbine similar to Fig. 13; Fig. 1 5 shows yet another wind turbine with an extended hub; Fig. 16 shows a wind turbine similar to Fig.

15 with additional bracing; and, Fig. 17 shows yet another embodiment of wind turbine with an extended hub.

Figs. 1a to 1d are respectively an end view, a front view, an oblique view and a plan view of a first embodiment of vertical axis wind turbine in accordance with the present inven tion. This is a braced, two-blade V-configuration, fixed geometry wind turbine. The two blades 10 and 11 are mounted on a support tower 12 from which a rotatable shaft 14 extends vertically upwards. Bracing cables 16 extend from the top of the rotatable shaft 14 to each of the blades 10, 11. In this embodiment the bracing cables extend at an upwardly inclined angle from the shaft to the blades. The blades 10, 11 are shown as having variable pitch tips 15 for overspeed control.

Fig. 2 shows a similar embodiment of wind turbine, again having two blades 10 and 11.

The device again comprises a support tower 12 and a rotatable shaft 14 from which bracing cables, rods or wires 16 extend to each blade. In this embodiment the blades 10 and 11 are mounted on the rotatable shaft 14 so that they can be tilted, each about a horizontal pivot axis, whereby the blades can be folded up like an umbrella to assist erection and/or transportation of the turbine. The provision of tilting axes for the blades also permits the blades to be pivoted down to ground level for inspection, maintenance or replacement.

Fig. 3 shows another two-blade wind turbine of the same general type, but here the rotatable shaft 14 is much longer and extends above the top of the blades. The bracing cables, rods or wires 16 extend in a downward direction from adjacent to the top of the shaft 14 to attachment points on the blades 10 and 11. This illustrates the fact that the bracing cables, rods or wires can extend at any angle to the blades, depending upon the overall geometry of the wind turbine.

Fig. 4 shows yet another embodiment of two-blade wind turbine. In this embodiment the bracing means, whether cable, wire, rod or whatever, extends from one blade 10 to the other blade 11, instead of from the blades to the central shaft.

Fig. 5 shows a single blade wind turbine having just the one blade 10 inclined upwardly from the central rotatable shaft 14. In this embodiment a counterweight 18 is mounted on the end of a short arm 19 and is positioned diametrically opposite to the blade 10.

Bracing cables or the like 16 extend from the top of the shaft 14 both to the blade 10 and to the counterweight arm 19.

Fig. 6 shows yet another embodiment of vertical axis wind turbine. In this embodiment the blades 10 and 11 are jointed to the hub by pins. In this embodiment the tie braces 16 from the blades to the central shaft 14 extend horizontally and may be cables or rigid rods for example.

Fig. 7 shows how the wind turbine of Fig. 6 is movable so that the blades 10 and 11 are lowered to a substantially horizontal position with an accompanying lengthening of the tie braces 16. The tie braces 16 may be hydraulically or pneumatically extensible.

Fig. 8 shows a wind turbine similar to that of Fig. 7, but here the blades 10 and 11 are mounted rigidly with the hub 20 for rotation on the tower.

Fig. 9 shows a single blade, vertical axis wind turbine with a variable geometry V-type configuration, and with a counterweight 18 mounted on an arm 19 and positioned above the hub 20. As in the embodiment shown in Fig. 5, both the counterweight arm 19 and the blade 10 are tied by extensible bracing means 16 to the central shaft 14.

Fig. 10 shows an embodiment of wind turbine similar to that shown in Fig. 9, but here the turbine is of fixed geometry, not variable geometry.

Fig. 11 is a schematic diagram of a further embodiment of vertical axis wind turbine using two blades 10 and 11.

In this embodiment, instead of using a solid tower, the turbine uses a vertical post 21 with a generally cylindrical plate 22 at the top of it, with a rotatable shaft 14 extending above the plate. Guy ropes, wires or cables 23 extend from the plate 2; to the ground or other support surface on which the turbine is mounted. The blades 10 and 11 are here shown as being provided with aerodynamic control devices 24 at the tips of the blades.

Further details of these control devices are given in our copending UK Patent Application No. 8507875.

Figs. 12a to 12d are respectively an end view, a front view, an oblique view and a plan view of yet another embodiment of vertical axis wind turbine in accordance with the present invention. This is a cantilevered single blade turbine with a counterweight 18 positioned above the hub. Again, restraining cables 16 are provided for varying the tilt angle of the blade 10 and of the counterweight. The normal operating position of the blade lOis shown in solid outline, with the conical swept area indicated in broken lines.

The "parked" position of the blade 10 is a horizontal position and is also shown by broken lines. In this embodiment the blade 10 and counterweight arm 19 are connected by pivot means to the central hub 20.

Fig. 13 shows a modified embodiment of vertical axis wind turbine. Here, a pylon or shaft 30 is mounted rotatably onthe top of a tower 12. The pylon 30 has horizontally extending arms 32 adjacent to its base which constitute an extended hub for the turbine.

The blades 10 are connected at their lower ends to the outer ends of the pylon arms 32.

Rigid bracing struts 34 extend between the pylon and the blades. Bracing cables 16 are provided between the two blades 10 and the top of the shaft portion of the pylon 30. The angle a which the blades 10 make with the vertical can be arranged to lie within the range 0-80 , although an angle of about 45" is preferred.

Fig. 14 shows a wind turbine similar to Fig.

13, but here the bracing struts 34 are omitted and the blades 10 are integral with the horizontally extending arms 32 of the central pylon 30.

Fig. 15 shows a simplified version of the extended hub wind turbine, where a single bracing cable 16 extends from one blade 10 to the other blade 10, and the double blade is mounted for rotation directly on top of the tower 12.

Fig. 16 shows a wind turbine similar to Fig.

15, but here two bracing cables 16 are used, in a cross-over configuration such that the cables or rods 16 each extend from adjacent to the upper end of a blade 10 down to the outer end of the opposite horizontal arm 32 of the extended hub.

Fig. 17 shows a wind turbine similar to that shown in Fig. 14, but with the blades 10 each extending vertically upwards from the ends of the horizontal support arms 32 of the extended hub.

The fluid turbine device of the present invention has wide application. -For example, it can be used as a means of wind-assisted ship propulsion. It also has potential uses as an aircraft, hovercraft or ship propeller, and also as a fan or pump.

Claims

1. An aerodynamic device comprising a pair of upwardly inclined blades, a support tower below the blades which is short in relation to the length of the blades supporting the blades for rotation about a vertical axis, and bracing means extending directly from blade to blade.

2. An aerodynamic device comprising one or more upwardly inclined blades, a support tower below the blade or blades which is short in relation to the length of the blade or blades supporting the blade or blades for rotation about a vertical axis, and bracing means extending from the or each blade to a central post on said axis.

3. 7 device according to claim 1 or 2, having a pair of blades extending upwardly from the ends of horizontally extending arms positioned adjacent to the top of the support tower, thereby to give the device a relatively wide hub.

4. A device according to claim 3, in which the blades extend upwards at an angle of about 45Q to the vertical.

5. A device according to claim 3 when dependent on claim 1, in which the bracing means extends horizontally from blade to blade.

6. A device according to claim 3 when dependent on claim 1, in which the bracing means comprises crossed ties extending from the respective blades to the opposite horizontally extending arms or the opposite blade.

7. A device according to claim 2, in which the central post extends upwards above the top of the blade or blades.

8. A device according to claim 3 when dependent on claim 2, in which said bracing means comprises cables or wires extending from the blades to the top of the central post and rigid strut means extending from the blades to a lower portion of the central post.

9. An aerodynamic device substantially as hereinbefore described with reference to any one of the Figures of the accompanying drawings.