GB2241747A - Turbine or impeller rotor - Google Patents

Abstract

A turbine or impeller rotor of the type comprising a plurality of vanes 1, 2, or (32, 33, fig 4) mounted in at least one circumferential array around a common axis of rotation 8, (27) of the rotor, each vane being rotatable about an individual axis 3 spaced from the common axis of rotation under the control of a linkage mechanism 11, 12, 13, 14; (40-45, fig 5) which constrains each of the vanes to turn through an angle about its individual axis (3) which is one half of the angle turned by the vane about the common axis of rotation and in the opposite sense. Each vane is formed of a flexible laminar material allowing it to adopt a curved configuration to enhance the contribution to the thrust of the impeller or 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 flow of the fluid. A plurality of vanes carried on respective arms of the rotor may also be provided. A turbine of this type may be used to drive either an impeller of this type or a screw propeller to provide propulsion for a boat. <IMAGE>

Description

A ROTOR FOR A TURBINE OR IMPELLER This invention relates generally to a rotor suitable for use either as a turbine or as an impeller which incorporates vanes rotating in a controlled manner about individual axes different from that of the rotor itself.

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. In either case such a rotor may be termed an impeller.

A number of different rotor configurations are known the most common of which is the conventional windmill having rigid radially extending blades turning in a plane perpendicular to the direction of the wind. Such rotors have the disadvantage that, for efficiency, they have to be designed to rotate relatively fast which makes them susceptible to damage by vibration and centrifugal forces, especially in winds of higher than average speed, and some designs are not self-starting. Vertical axis rotors are also known, and these have the advantage of being omnidirectional and relatively slow speed, which overcomes some of the disadvantages of conventional windmill rotors, but they have themselves the disadvantage of being highly inefficient resulting in a very low useful torque on any driven rotor shaft.

For a long time it has been known that a 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 has considerable potential for deriving torque from a flowing medium.One earlier Patent incorporating a rotor of this type is UK Patent 1,486,338 which describes a wind or water powered machine comprising a rotatable shaft having a plurality of drive vanes which are rotatably mounted on supports extending radially outwardly from the shaft so that the drive vanes can rotate about equispaced axes parallel with the shaft, a rudder vane mounted on a support rotatably mounted on the shaft, or a remote shaft, and a drive connection between each drive vane and the rudder vane support to provide a gear ratio of 1:2 between the drive vanes and the rudder support. This known rotor employs, as indeed do all known rotors of this general type, a rigid vane structure mounted on rigid radially extending arms.The linkage mechanism for ensuring the appropriate rotation of the individual vanes about their individual axes with respect to the rotor assembly as a whole comprises an array of belts or chains, although in other known rotors conventional gears or sprockets are employed. Similar such rotors are described in International application W085/01780, United States Patent 4125343 and European Patent application EP-A-276904. In this latter application the vanes are composed of metallic frames surrounding an area filled by a textile canvas stretched tightly within the frame to form a flat blade.

Despite the apparent potential for relatively efficient conversion of the kinetic energy in the flowing medium to rotary torque such rotors have not to date ever satisfactorily achieved their apparent potential and it is believed that one feature mitigating against this is the use of rigid blades which, because of their form, create significant turbulence in the flowing medium resulting in a high degree of drag acting against the rotation of the rotor assembly as a whole when the blade is inclined at an angle to the flow of the fluid. The present invention seeks to provide a rotor structure suitable for use as a turbine or as an impeller rotor in which this disadvantage is overcome by use of a novel vane configuration.

According to one aspect of the present invention, therefore, there is provided 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 flow of the fluid.

By utilising a flexible form or structure for the vane instead of the entirely rigid configuration known from the prior art such rotors, each vane can adopt what is in essence an aerofoil or hydrofoil shape when acted on by the flowing fluid. Each vane may comprise a flexible laminar panel having reinforcing or stiffening linear members along the edges thereof which are the leading and trailing edges in use of the rotor. In such a configuration it is envisaged that the dimension of the flexible panel between the stiffening members is slightly greater than the distance between the stiffening members themselves so as to leave a "bag' of relatively free flexible material capable of adapting its shape in dependence on the fluid-dynamic forces acting on it.

Alternatively, each flexible vane may comprise a plurality of rigid panels hingedly connected together along edges substantially parallel to the individual axis of rotation of the vane. Such a structure may be formed, for example, by a plurality of narrow strips joined together edge-toedge.

In one embodiment of the invention the vanes are oriented such that the individual axis of rotation of each vane is inclined to the said common axis of rotation of the rotor although, in other embodiments, the individual axis of rotation of each vane may be parallel to the said common axis. In embodiments in which the individual axis of rotation of each vane is inclined to the said common axis it is preferable for each vane to be triangular in plan form whereas, in embodiments having a configuration with the individual axis of rotation parallel to the common axis, although a triangular plan form vane configuration is acceptable, a rectangular plan form may be more effective.

For efficiency it may be found that the location of the individual axis of rotation of each vane is preferably within the outline of the vane although it is entirely possible to envisage a structure in which the vanes are held on a supporting framework such that they are capable of rotation about individual axes which do not pass through the outline of the vane. Such a configuration may, in some circumstances, having advantages in terms of balancing of the hydrodynamic or aerodynamic forces acting on the vanes.

Although, as mentioned above, the flexible laminar material or hinged panels of each vane may be freely flexible to adopt a curved configuration under the influence only of the fluid-dynamic forces acting on the vane, embodiments of the invention may be formed in which the flexible laminar material of each vane is a stressed panel which can be held in a curved configuration by a configuration control mechanism operable to flex the panel to a curved shape which is convex to one side or the other of the general plane defined by the panel edges in dependence on the position of the vane with respect to a reference datum of the rotor.

According to a second aspect of the present invention 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 the vanes are carried on radial arms and there are provided a plurality of vanes on each arm.In this way, by suitably positioning the vanes along the arms, the aerodynamic or hydrodynamic slot effect of fluid flowing between and over the vanes can be used to increase the torque exerted on the rotor as a whole by each individual vane, in the case of a turbine rotor, or to increase the thrust exerted by the rotor on the fluid medium, in the case of an impeller rotor.

The vanes on any one arm of the rotor may be linked to turn in unison or to turn at different rates to accommodate the different instantaneous fluid flow conditions which will differ at different radial positions along the arm.

The rotation of the vanes about their individual axes may be linearly or non-linearly related to the rotation of the vanes about the common axis of the rotor. It will be appreciated that a plane is defined for each vane by its individual axis and the common axis of the rotor. When this plane is perpendicular to the direction of flow of the fluid with respect to the rotor the vane may be parallel to the flow or perpendicular to the flow depending on which side of the axis it is located so that it offers the maximum resistance to the oncoming flow on one side and the minimum resistance on the other.If a geared or pulley linkage mechanism is utilised the individual vanes may turn, with respect to the rotor assembly itself, regularly between the two orthogonal positions in the above-defined locations so that when the plane defined by the individual axis and the common rotor axis is perpendicular to the above-defined location, namely parallel to the flow of the fluid, the vane may be at 45" to the flow, namely midway between the perpendicular and parallel positions it adopts when the said plane is perpendicular to the flow, and at intermediate positions between this quadrantal points the individual vanes may turn through an angle which is always related by the same ratio to the angle through which the rotor as a whole is turning about the common rotor axis.

However, in order to maximise the effectiveness of the rotor, it would clearly be preferable for the vane on that side of the axis where it presents minimum resistance to the flow to be positioned exactly parallel to the flow for the whole of the semi-circle and, if this were possible, to be exactly perpendicular to the flow over the whole of the other semi-circle. This could be achieved by means of a cam arrangement or by non-circular gears which would slow the rotation of the vane whilst traversing one semicircle and speed the rotation of the vane whilst traversing the other semi-circle so that, during the whole of one rotation about the common axis, the vane still turns through only ISO'.

The present invention, according to another aspect, provides a propulsion unit for a water craft, comprising a turbine rotor as defined hereinabove, adapted to be driven to rotate by the wind, propeller means, and a drive transmission system for transmitting drive to the said propeller means from the turbine rotor.

The propeller means may, for example, comprise an impeller rotor as defined hereinabove or may be some other form of propeller such as a screw propeller.

Various embodiments of the present 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; 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 shows in plan view an alternative three arm rotor with three blades supported on each arm, demonstrating how the rotor design and blade configuration can be altered within the principles of the invention; Figure 4 is a schematic side view of a water craft fitted with a propulsion system incorporating a turbine rotor formed according to the principles of the present invention; ; Figure 5 is an enlarged sectional view of the mast and boom assembly; Figure 6 is an enlarged sectional view of the mast bdse and transmission shaft of the embodiment of Figure 4; and Figure 7 is a schematic view of the propulsion unit driven by the drive shaft of Figure 6.

Referring now to 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 shaft 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 90' 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 0", 180' or 3600. When the broad faces of the vanes are aligned into the wind as occurs when angle 18 or 19 measure 904 or 2700, the vanes offer least resistance to the wind.

In rotor position 1, angle 18 of blade 1 in Figure 2 measures 0' while angle 19 of blade 2 measures 90" 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 general "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 90" or 270' while angle 19 measures 180' or 360" 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.

A rotor could consist of any number of blades in various configurations within the rotor assembly. Figure 3 is a plan view of a three arm rotor with each arm 20 carrying three blades 21, demonstrating the variation in design possible within the principles of this invention. The Figure 3 embodiment has the advantage that the air flow between adjacent vanes on an arm increases the aerodynamic "lift" effect of the aerofoil improving the performance of the rotor.

Figure 5 shows a water craft generally indicated 25 fitted with a propulsion unit incorporating a turbine rotor generally indicated 26 formed according to the principles of the present invention. The water craft 25 comprises a hull 26 having an upright mast 27 which, unlike a conventional sailing boat mast, is mounted to be rotatable about its own axis and, in this embodiment, carries two transversely extending support arms 28, 29 at the free ends of which are pivoted the mid-points of respective booms 30, 31 to which respective triangular vanes 32, 33 are secured. In other embodiments, not shown, three or more support arms may be provided, equi-angularly spaced around the mast 27. The apex of each triangular vane 32, 33 is secured to a respective swivel 34, 35 at the mast head 36 and each vane 32, 33 is provided with wire reinforcement at the edges 37, 38 (only the edges of the vane 33 are visible in Figure 4). Transverse reinforcing battens 39 parallel to the boom 31 are fitted in pockets extending from the edge 37 to the edge 38 of each vane.

The battens 39 allow each vane to flex to a curved aerofoil shape in the same way as the unstaid flexible panels 24 can flex in the embodiment of Figure 1 although, unlike these panels, the vanes 33 are not provided with an entirely surrounding rigid frame corresponding to the frame 22. In part this is rendered unnecessary by the triangular outline of the vanes 32, 33 and in part this function is performed by the reinforcing wires on the edges 37, 38.

Turning now to Figures 5 and 6, the structure within the hollow mast 27 and the support arms 28, 29 can be seen.

The vanes 32, 33 and support arms 28, 29 carrying the booms 30, 31 are identical to one another and accordingly only the vane 33, boom 31 and support arm 29 will be described in detail.

Within the support arm 29 is a support arm drive shaft 37 mounted in two bearings 38, 39 and having a bevel gear 40 at its radially inner end and a bevel gear 41 at its radially outer end. The bevel gear 41 at the radially outer end of the support arm drive shaft 37 meshes with a bevel gear 42 born transversely within the support arm 29 and fixedly secured by a shaft 43 to the boom 31 so that rotation of the support arm drive shaft 37 can be transmitted to the boom 31 as rotation about the shaft 43 which, as can be seen from Figure 4, is in alignment with a median axis of the vane 33 passing through the apex secured to the swivel 35.

The bevel gear 40 at the radially inner end of the support arm drive shaft 37 meshes with a further bevel gear 44 at the upper end of a hollow control shaft 45 the lower end of which bears a pulley 46 (see Figure 6) controlled by a control wire 47 looped around the pulley. Halyards controlling the raising and lowering of the vanes 32, 33 pass through the centre of the mast 27 and are indicated by the reference numerals 48 in Figures 5 and 6. A main halyard winch 49 is secured to the bottom of the hollow control shaft 45. The control wire 47 controls the angular orientation of the hollow shaft 45 via the pulley 46 thereby determining, as with the control wheel 16 in the embodiment of Figure 1, the relative orientation of the vanes with respect to the rotor as a whole thereby enabling the rotor to be adjusted so that it effectively faces into the wind to obtain maximum benefit from it.

As can be seen in Figure 6, the mast 27 carries a bevel gear 50 at its lower end, which meshes with a bevel gear 51 carried at the mast end of a drive shaft 52 engaged via a clutch 53 to a main transmission shaft 54 (Figure 7).

The rotation of the mast 27 may be slowed or stopped by means of a disc brake comprising a disc 55 engaged by a brake calliper 56 as can be seen in Figure 6.

At the rear end of the drive shaft 54 this is carried in a transmission housing 57 within which a bevel gear 58 at the end of the drive shaft, meshing with a further bevel gear 59 mounted on a hollow drive shaft 60 carrying a drive rotor 61 at its lower end. Through the drive shaft 60 extends a control rod 62 an upper end of which carries a pulley 63 over which passes a control line 64. At its lower end the control rod 62 carries a bevel gear 65 which meshes with two planet gears 66, 67 carried on the rotor head 61, which in turn mesh with two spur gears 68, 69 secured to the ends of paddle shafts 70, 71 having paddle blades 72, 73.

With the control wire 64 held stationary so that the control shaft 62 is fixed, rotation of the main transmission shaft 54 causes the drive shaft 60 to rotate carrying with it the rotor head 61 thus forcing the paddles 72, 73 to orbit. As the paddles orbit the spur gears 68, 69 are driven to rotate about their axes by the bevel gears 66, 67 rolling over the stationary bevel gear 65. The diameters of these final transmission gears are chosen such that each of the paddles 72, 73 performs one half of a single revolution about its own axis during the course of one orbit about the axis of the drive shaft 60 so that it follows a motion identical to that of the vanes in the embodiment of Figure 1. Displacement of the control wire 64 turns the pulley 63 and thus the control shaft 62 to change the orientation of the bevel gear 65 and thus modify the angular orientation at which the blades 72,73 are parallel to and perpendicular to the axis of the vessel thereby effectively creating a steering effect.

In any of the embodiments described above there may be two, three, four or even more arms carrying one or a plurality of vanes. Embodiments having two or three arms have been illustrated for convenience only.

Claims (17)

1. 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 whereby to enhance the contribution to the thrust of the impeller or 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 flow of the fluid.

2. A turbine or impeller rotor as claimed in Claim 1, in which each vane comprises a flexible laminar panel having reinforcing or stiffening linear members along the edges thereof which are the leading and trailing edges in use of the rotor.

3. A turbine or impeller rotor as claimed in Claim 1 or Claim 2, in which the vanes are oriented such that the said individual axis of rotation of each vane is inclined to the said common axis of rotation of the rotor.

4. A turbine or impeller rotor as claimed in Claim 1 or Claim 2, in which the vanes are oriented such that the said individual axis of rotation of each vane is parallel to the said common axis of rotation of the rotor.

5. A turbine or impeller rotor as claimed in any preceding Claim, in which each vane is triangular in plan form.

6. A turbine or impeller rotor as claimed in any of Claims 1 to 4, in which each vane is rectangular in plan form.

7. A turbine or impeller rotor as claimed in any preceding Claim in which the individual axis of rotation of each vane lies within the outline of the vane.

8. A turbine or impeller rotor as claimed in any preceding Claim, in which the flexible laminar material of each vane is freely flexible to adopt a curved configuration under the influence only of the fluid dynamic forces acting thereon.

9. A turbine or impeller rotor as claimed in any of Claims 1 to 7, in which the flexible laminar material of each vane is a stressed panel which can be held in a curved configuration by a configuration control mechanism operable to flex the panel to a curved shape convex to one side or the other of the general plane defined by the panel edges in dependence on the position of the vane with respect to a reference datum of the rotor.

10. 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 the vanes are carried on radial arms and there are provided a plurality of vanes on each arm.

11. A turbine or impeller rotor as claimed in Claim 10, in which the vanes on an arm are linked to turn in unison.

12. A turbine or impeller rotor as claimed in any preceding Claim, in which the rotation of the vanes about their individual axes is non-linearly related to the rotation of the vanes about the common axis of the rotor.

13. A turbine or impeller rotor as claimed in any of Claims 1 to 8, in which each flexible vane comprises a plurality of rigid panels hingedly connected together along edges substantially parallel to the individual axis of rotation of the vane.

14. A turbine or impeller rotor substantially as hereinbefore described with reference to, and as shown in, the accompanying drawings.

15. A propulsion unit for a water craft, comprising a turbine rotor as claimed in any preceding Claim, adapted to be driven to rotate by the wind, propeller means, and a drive transmission system for transmitting drive to the said propeller means.

16. A propulsion unit for a water craft as claimed in claim 14, in which the propeller means comprise an impeller rotor as claimed in any of Claims 1 to 12.

17. A propulsion unit for a water craft, substantially as hereinbefore described with reference to and as shown in the accompanying drawings.