GB2263735A

GB2263735A - Blade adjustment/control of a e.g. wind turbine

Info

Publication number: GB2263735A
Application number: GB9202038A
Authority: GB
Inventors: John Jason Paul Goodden
Original assignee: Individual
Current assignee: Individual
Priority date: 1992-01-31
Filing date: 1992-01-31
Publication date: 1993-08-04
Also published as: GB9202038D0

Abstract

A vane assembly for use in a tubular or impeller rotor of the type comprising a plurality of vane assemblies 31 mounted in at least one circumferential array around a common axis of rotation (8) of the rotor and including a vane turnable about an individual axis 35, 34a spaced radially from the said common axis and controlled by a linkage mechanism (11), 12, (13, 14 Fig 3) which constrains each vane to turn through an angle into its individual axis 35, 34a which is one half of the angle turned by the vane about the common axis of the rotor and in the opposite sense, in which the vane assembly includes at least two rigid vane parts 33 pivotable along a hinge axis 34c which is substantially parallel to, but offset from the individual vane axis and which by means of a control mechanism 35, 38, 37, 38, 39 driven by the linkage mechanism of the rotor, permits the vane parts to vary their relative configuration in coordination with the rotation of the rotor in such a way as to enhance the fluid-dynamically generated thrust or torque of the rotor. <IMAGE>

Description

DESCRIPTION The present invention relates to an improved vane assembly for a turbine or an impeller rotor and to a rotor incorporating such a vane assembly.

Turbine rotors are conventionally used to capture and convert to rotary torque, kinetic energy present within a flowing fluid such as in the air as wind, or flowing water as in a river or tides. Certain rotors can also be used in reverse by applying a torque to the rotor and causing thrust to be generated that either induces flow within the medium or propels the rotor through the medium: such a rotor may be termed an impeller.

The invention is concerned with a vane assembly for such an impeller or turbine rotor and, in particular, with an improved vane assembly for incorporation in a rotor such as that which is the subject of the Applicant's prior UK Patent Application No. 2241747. This relates to a turbine or impeller rotor of the type comprising a plurality of vanes mounted in at least one circumferential array around a common axis of rotation of the rotor, each vane being turnable about an individual axis spaced radially from the said common axis of rotation under the control of a linkage mechanism which constrains each of the vanes to turn through an angle about its individual axis which is one half of the angle turned by the vane about the common axis of the rotor and in the opposite sense, in which each vane is formed of a flexible laminar material allowing it to adopt a curved configuration under the influence of a flowing medium whereby to enhance the contribution to the thrust of the impeller or to the torque of the turbine made by a vane due to the fluid-dynamic force generated by a pressure differential created by the fluid medium flowing over the curved surfaces of the vane when in an orientation inclined to the direction of the flow of the fluid.

The flexible vane structure employed in the above rotor enables the vane to adopt, in essence, an aerofoil or hydrofoil shape when acted upon by the flowing fluid, in use, and thus reduces the turbulence and drag created in comparison with the prior art rigid vanes. This, in turn, means that the rotor is more energy-efficient than prior-art such rotors but it has been found that the flexible vanes suffer from a certain lack of robustness, particularly in large-scale equipment.

The object of the present invention is to provide a vane for incorporation in a turbine or impeller rotor which is more energy efficient than the prior art rigid vane structures but more durable than the applicant's flexible vane described in UK Patent Application No 2241747.

Accordingly, the present invention provides a vane assembly for use in a turbine or impeller rotor of the type comprising a plurality of vane assemblies mounted in at least one circumferential array around a common axis of rotation of the rotor, each vane assembly including a vane turnable about an individual axis spaced radially from the said common axis of rotation under the control of a linkage mechanism which constrains each of the vanes to turn through an angle about its individual axis which is one half of the angle turned by the vane about the common axis of the rotor and in the opposite sense, in which the vane assembly includes at least two rigid vane parts whose relative configuration can be changed by means of a control mechanism connectible to the linkage mechanism of the rotor such that the control mechanism operates to change the configuration of the parts in coordination with the rotation of the rotor whereby to enhance the contribution to the thrust of the impeller or the torque of the turbine made by the vane due to the fluid-dynamic force generated by a pressure differential created by the fluid medium flowing over the surfaces of the vane when in an orientation inclined to the direction of flow of the fluid.

The vane assembly may include one vane part pivotable relative to a fixed support but preferably includes at least two vane parts pivotable relative to each other to change the vane configuration, preferably about an axis or axes parallel to but spaced from the said individual axis of the vane. The vane configuration may be changed between one in which the vane presents a minimum resistance to flow, in use in a rotor, when the vane assembly is at that point in its rotational path at which it is travelling against the fluid flow and a configuration, at the opposite point in the rotational path, in which it makes a maximum contribution to the flow or torque; between these positions the vane parts may be mutually inclined and inclined to the fluid flow so as to provide "lift" in a manner similar to that provided by the flexible vane of the applicant's earlier application. The present invention thus, effectively, provides a mechanical means for changing the configuration of a rigid structure to simulate, as far as possible, the aerodynamic effect of the flexible vane.

In a preferred embodiment of the invention, the vane parts are at the outer end of an arm which projects radially from a shaft defining the said individual axis, the shaft projecting forwardly of the overall direction of rotation of the rotor in which the vane assembly is incorporated in use. Preferably the vane includes two parts hinged to a support shaft carried at the outer end of the arm and arranged with its axis parallel to the said individual axis. The control for the mutual pivoting of the vane parts is preferably integrated with a mechanism for rotating the vane as a whole about the individual axis so as to achieve the desired coordination of these movements.

The present invention also relates to a turbine or impeller rotor of the type described above incorporating a plurality of vane assemblies as described above mounted in at least one circumferential array around the common axis of rotation of the rotor.

One embodiment of a rotor incorporating the vanes of the invention will now be more particularly described, by way of example, with reference to the accompanying drawings in which: Figure 1 shows in perspective a simple twin blade wind turbine rotor supported by bearings mounted within a gearbox and generator house, according to the prior art; Figure 2 shows in plan view the relative alignment of the blades and is supplemented by Table 1 to show how their alignment alters as the primary shaft rotates; Figure 3 is a plan view of the wind turbine rotor according to the present invention; and Figure 4 is a perspective view, on an enlarged scale, of part of the rotor of Figure 3.

With reference to Figures 1 and 2 of the drawings, these show a wind turbine rotor as described and illustrated in the applicant's prior Patent Application No. 2241747, mentioned above, and which are incorporated herein by way of reference. In the rotor of Figures 1 and 2, two vanes 1 and 2 are mounted on vertical shafts 3 which are secured by a framework 22 to the vanes 1, 2 and are attached to support arms 4 and 5 by a top end shaft bearing 6 and a combined shaft and vertical thrust bearing 7. The vanes 1, 2 are rotatable about the vertical axes of the shafts 3. Each vane 1, 2 comprises a surrounding rigid framework 22 spanned by a flexible panel 24 which, as can be seen, is urged by the wind to adopt a curved aerofoil like shape.

The support arms 4 and 5 are mounted on the primary vertical shaft 8 which is supported by a shaft bearing 9 mounted in the roof of the generator house 10 and by additional thrust and shaft bearings which are not shown inside the generator house.

The complete rotor assembly can rotate about the vertical axis of the primary shaft 8. The rotation of the vanes is linked by link shafts 12 and sets of bevelled gears 11 and 14. Gear sets 11 link the base of the vane shafts 3 and the outer end of the link shafts 12 which are supported by bearing mounts underneath the lower support arms 5. A hollow control tube 13 freely turns on shaft bearings on the face of the primary shaft 8. The top of the control shaft is linked to the inner ends of the link shafts 12 by the bevelled gears 14. The control tube 13 is controlled by a further set of bevelled gears 15 driven by a shaft and control wheel 16.

With the control tube 13 held stationary by the control wheel 16, the link shafts 12 are compelled to turn by the gears 14 as the primary shaft 8 rotates inside the control tube 13. As the link shafts turn, the blades are caused to rotate relative to the rotor assembly by the gears 11. The combined ratio of the two sets of gears 11 and 14 is such that the blades are caused to rotate by one half of the angle through which the primary shaft 8 turns, with the control tube 13 being held stationary.

By turning the control wheel 16 the alignment of the vanes can be altered although the orientation of the vanes with respect to each other is fixed.

Each vane is oriented so that when its rotational axis moves into a position at which it is offset in a given reference direction from the primary shaft axis, the vane is aligned with a set orientation which is the same for each vane as it passes the reference position. Figure 2 is a plan view of the same rotor showing the relative orientation of the vanes. In this example, two vanes are mounted on opposite sides of the rotor such that their relative orientation will be consistently phase shifted by 900 with respect to one another.

Table 1 lists the relative orientation of the vanes at various positions of the rotor as it rotates through a 360 degree revolution. The vanes' orientations are listed as two angles, 18 and 19 shown in Figure 2, which denote the extent through which the vanes turn relative to their support assembly, and are compared with angle 17, the angle through which the rotor shaft and vane support assembly turns. All angles are measured from an arbitrary start defined by the direction in which the line joining the rotational axis of blade 1 with the primary shaft axis is perpendicular to the direction of the wind.

TABLE 1 Rotor Angle 17 Angle 18 Angle 19 Position (degrees) (degrees) (degrees) 1 0 0 90 2 45 22.5 112.5 3 90 45 135 4 135 67.5 157.5 5 180 90 180 6 225 112.5 202.5 7 270 135 225 8 315 157.5 247.5 9 360 180 270 Each vane thus rotates through 1800 for each 360 degree revolution of the primary shaft. The vanes generate maximum drag when they present their maximum area to the wind as occurs when angles 18 or 19 measure 00, 1800 or 3600. When the broad faces of the vanes are aligned into the wind as occurs when angle 18 or 19 measure 900 or 270 , the vanes offer least resistance to the wind.

In rotor position 1, angle 18 of the blade 1 in Figure 2 measures 00 while angle 19 of the blade 2 measures 900 such that a clockwise turning moment is induced on the rotor by the imbalance of drag forces acting on the different vanes in the wind. As the rotor turns clockwise in this wind the vanes angle themselves to the wind such that they generate "lift" as well as drag, this effect being due to the aerofoil shape adopted by the flexible laminar panels 24. Depending on the speed of the wind, the speed of rotation of the rotor and the resultant speed and direction of the airflow past the vanes, the combined "lift" forces on the vanes will contribute to the clockwise turning moment acting on the rotor.

In the same wind direction, anti-clockwise turning moments can be induced on the rotor by turning the control wheel 16 such that, at the rotor start position 1, angle 18 measures 900 or 270" while angle 19 measures 1800 or 3600 respectively.

The control wheel can be linked to a rudder sensitive to the wind direction either by direct mechanical linkage or by remote controlled drive so that the alignment of the vanes is automatically adjusted to best capture the wind energy in winds from differing directions.

The precise method of turning and controlling the vanes is not critical to the principle of this invention. For example, the link shaft and bevelled gear sets could be replaced by chains linking sprockets on the control shaft and the blade shafts, or linkage could be achieved by a series of interlocking cogs.

With reference now to Figures 3 and 4 of the drawings, these show a rotor generally indicated 30 which operates on substantially the same principle as the rotor described above, the main difference being in the improved structure of the vanes themselves. Parts similar to those shown in Figures 1 and 2 are indicated by the same reference numerals and will not be described again.

A further difference, though not in principle, lies in the fact that the rotor 30 is shown with four identical vane assemblies, each generally indicated 31, supported at the ends of respective support arms 5 arranged at 900 to each other to form a cross centred on the primary shaft 8. The upper support arms 4 of Figure 1 and 2 are omitted since the vane assemblies 31 are sufficiently rigid to be self-supporting though additional supports could be provided if additional strengthening were required; for example a frame support similar to that described in my earlier UK patent application No 2241747, with a pivot pin supported both at the top and at the bottom.

With reference now, in particular, to Figure 4 this shows that each vane assembly 31 includes a vane 32 constituted by two similar, substantially rigid, rectangular panel members 33 hinged together about adjacent vertical edges on an upper portion 34c of a support shaft 34 parallel to the primary shaft 8; that is, the panels 33 are hinged for relative pivotal movement about an axis X-X of the shaft 34 which is vertical. Each panel member 33, although being thin in comparison with its vertical height and breadth, has sufficient thickness to accommodate an edge slot 39, shown in broken outline and which will be described below.

The support shaft 34 corresponds to the support shaft 3 of Figure 1 but its lower end is cranked such that the hinge axis X-X is offset from the axis of a lower portion 34a of the shaft which is supported directly by the support arm 5 and is fixed against rotation relative thereto. The cranked arm of the shaft 34, indicated 34b, connecting the upper and lower portions thereof extends horizontally at right angles to the support arm 5, forwardly of the direction of rotation of the rotor 30.

The vane assembly 31 further includes a control member generally indicated 35 for controlling the rotation and relative pivoting of the hinged vane panels 33 connected via the bevel gear set 11 to the link shaft 12. More particularly the control member 35 has a central sleeve 36 coaxially mounted for the free rotation on the lower portion 34a of the vane support shaft 34 and fixed to the gear lla of the gear set 11 which is also freely rotatable on the lower shaft portion 34a. The sleeve 36 carries two arms 37 which project from it in opposite directions and at right angles to the axis thereof. The ends of the control arms 37 remote from the sleeve 36 carry upwardly projecting pins 38 each engaged in a respective one of the slots 39 formed in the lower edges of the vane panels 33 so as to be slidable longitudinally of the slot. In this example, each slot 39 terminates at one end close to the free vertical edge of the panel 33 and extends for about two-thirds the breadth of the panel.

It can be seen that the dimensions of the panels 33 can be extended without altering the dimensions of the control arms 37 or those of the slot 39 so that the orientation of the panels in relation to one another and to the rotor assembly is unaltered. The length of the offset crank 34b relative to the length of the support arms 37 determined the geometry of the 'aerofoil' formed by the panels 33 and could be either extended or reduced to increase or decrease respectively the inclined angles of the panels in relation to one another at their maximum inclanation.

The operation of the rotor 30 as a turbine will now be described with reference to a wind flowing in the direction of the arrow A in Figure 1, the arms 5 of the cross-shaped support being parallel or perpendicular to this direction at the moment shown in the drawing.

The vane assemblies are arranged such that the rotor as a whole will rotate in the clockwise direction, indicated by the arrow B. For this purpose the vane assembly 31a to the left, indicated 31a, carried by an arm 5 perpendicular to the wind direction A is arranged to take maximum advantage of the wind: its two panels 33 are inclined at an obtuse angle to each other and are equally inclined to the wind direction A, presenting effectively a concave face to it. It will be seen that the control pins 38 are located equidistantly from the outer ends of the drive slots 39. The vane assembly 31c to the right, on the contrary, is arranged to present minimum resistance to the wind since this is, momentarily, travelling directly against the wind. The two panels 33 are thus pivoted into a position in which they are aligned parallel to each other and the wind direction.

The control pins 38 are located one at the inner end of its drive slot 39 in the leading panel 33 and the other at the outer end of its slot 39 in the trailing panel 33.

The two vane assemblies 31b and 31d which are supported by the support arms 5 which extend parallel to the wind direction A are arranged in configurations intermediate those of the other two vane assemblies 31a and 31c. It will be seen from Figure 3 that the two panels 33 of the vane assemblies 31b, 31d are equally inclined to each other and to the wind direction A but on opposite sides of the wind axis A since they are, effectively, both located on the leading sides of their support arms 5 by means of their cranked support shafts 34. In each case the control pins 38 are located at the outer ends of the drive slots 39 in the trailing panels and intermediate the ends of the slots 39 in the leading panels.The arrangement is such that they present a concave face to the wind and act, effectively, as aerofoils to contribute a turning movement which assists the rotation of the rotor 30.

It will be appreciated that, as in the embodiment of Figures 1 and 2, the rotation of the rotor 30 in the clockwise direction B, in use through the link mechanism constituted by the bevel gear sets 15 and 11, the link shafts 12 and the control members 35, drives the rotation of the vanes 32 in the anti-clockwise sense, shown by the arrows C, through 1800 for every 3600 of the rotation of the rotor as a whole. In this movement the control arm 35, adopts the same relative orientations as the panels 24 of the device described in relation to Figures 1 and 2. In addition to this rotation, however, the panel members 33 are also pivoted relative to each other by the reciprocating sliding engagement of the control member pins 38 in the panel slots 39. The combined rotational and hinged pivotal movements thus cause the configuration of the vanes 32 to progress gradually, as the rotor rotates, from the configuration shown at 31a through those shown at 31b, 31c and 31d in sequence and back to that of 31a.

It will be appreciated that the length of the arm 34b affects the geometry of the 'aerofoil' and can be chosen to obtain the optimum 'lift' effect in dependence on side conditions, such as typical average wind speeds. By contract without changing the geometry, the size of the panels may be varied (providing the slots 39 are kept to the same length) and in particular may be increased in length to maximise the 'dry' effect when perpendicular to the wind direction.

Claims

1. A vane assembly for use in a turbine or impeller rotor of the type comprising a plurality of vane assemblies mounted in at least one circumferential array around a common axis of rotation of the rotor, each vane assembly including a vane turnable about an individual axis spaced radially from the said common axis of rotation under the control of a linkage mechanism which constrains each of the vanes to turn through an angle about its individual axis which is one half of the angle turned by the vane about the common axis of the rotor and in the opposite sense, in which the vane assembly includes at least two rigid vane parts whose relative configuration can be changed by means of a control mechanism connectible to the linkage mechanism of the rotor such that the control mechanism operates to change the configuration of the parts in coordination with the rotation of the rotor.

2. A vane assembly as claimed in Claim 1, in which the vane parts are relatively pivotable about an axis or axes parallel but offset from the said individual axis of the vane.

3. A vane assembly as claimed in Claim 2, in which the vane parts are reciprocable between a configuration in which they are mutually inclined and a configuration in which they are substantially coplamour.

4. A vane assembly as claimed in Claim 3, in which the control mechanism for the change of configuration of the vane parts includes a cranked shaft, one portion of which defer.

Amendments to th claims have been filed as follows 1. A vane assembly for use in a turbine or impeller rotor of the type comprising 2 plurality of vane assemblies mounted in at least one circumferential array around a common axi of rotation of the rotor, each v5ne assembly including a vane turnable about an individual axis spaced radially fro the said common axis of rotation under the control of a linkage mechanism which constrains each of the vanes to turn through an angle about its individual axis which is one hal, of the angle turned by the vane about the common axis of the rotor and in the opposite sense, in which the vane assembly @ includes at least two rigid vane parts whose relative configuration can be changed by means o, a control mechanism connectible to the linkage mechanism of he rotor such that the control mechanism operates to change the configuration of the vane parts in coordination with the rotation of the rotor in such a way as to enhance the contribution to the thrust of the impeller or torque of the turbine made by the vane due to the fluid-dynamic force generated by a pressure differential created by the fluid medium lowing over the surface of the vane when in an orientation inclined to the direction of flow of the fluid.

A vane assembly as claimed in claim 1, in which the vane assembly is supported by a radial rotor arm.

3. A vane assembly as claimed in claims 1 and 2, in which the vane parts are relatively pivotable about a hinge axis

substantially parallel to, but offset from the said individual axis of the vane.

4, R vane assembly as claimed in claims 1 to 3, in which the hinge axis is offset within the same circumferential path around the said common axis of rotation of the rotor as the individual axis of the vane and in a direction which leads the individual vane axis when operating as a turbine or trails the individual vane axis when operating as an impeller 5, A vane assembly as claimed in claims 1 to 4 in which the hinged pivot of the vane parts is supported on a cranked support shaft emanating at the individual vane axis on the said radial rotor arm and terminating at the hinge is, vane vane assembly as claimed in claims 1 to 5, in which the control mechanism for the change of configuration of the vane parts includes a control member mounted for ree rotation ac--out an axis common with the individual axis of the vane and driven by the said linkage mechanism -n that the control member turns through an angle which is one half of the angle turned by the vane about the common axis of the rotor and in the opposite sense and from which radial control arms constrain the con+iguration Our the vane parts by a sliding mechanism linking the control arms each to a vane part 7.A vane assembly as claimed in claims 1 to 6, in which the parts are reciprocable between a configuration in which they are mutually inclined and d configuration in which the are

substantially coplanar.

8. A vane assembly as claimed in claims 1 to 7, in which the individual axis of rotation of each vane assembly is substantially parallel to the common axis of rotation of the rotor.

9. A vane assembly as claimed in claims 1 to 7, in which the individual axis of rotation of each vane assembly is inclined to the common axis of rotation of the rotor.

10. A vane assembly as claimed in claim 1 to 9, in which the vane parts are triangular in plan form.

11. A vane assembly as claimed in claims 1 to 8, in which the vane parts are rectangular in plan form.

12. A vane assembly as claimed in any preceding claim in which the rotation of the vane assembly or vane parts about the individual vane axis is non-linearly related to the rotation of the vane about the common axis of the rotor.

13. A vane assembly substantially as hereinbefore described with reference to, and as shown in, the accompanying drawings.