WO2009150427A2

WO2009150427A2 - Improvements in flat disc turbine generators

Info

Publication number: WO2009150427A2
Application number: PCT/GB2009/001462
Authority: WO
Inventors: Alan Watts; David Watts
Original assignee: Axiom Generators Ltd
Priority date: 2008-06-13
Filing date: 2009-06-10
Publication date: 2009-12-17
Also published as: WO2009150427A3; GB0810888D0; GB2460725A

Abstract

A turbine generator (1) comprising a rotatable shaft (10), a plurality of spaced apart parallel discs (8) carried on the shaft (10) so as to be rotationally fast therewith, and power generation means connected to the shaft (10) so as to be rotated thereby, the circular surface of each disc (8) having a plurality of recesses, dimples (26), grooves (27), vanes (28) or projections formed therein so as to increase the surface area. The turbine generator (1) further including a debris removal system for removing debris from between the discs (8) and a plate (6) for controlling the rotational speed of the discs (8). The plate (6) extends longitudinally parallel to the shaft (10) across the plurality of discs (8) proximate to the outer surface thereof and also extends partially around the circumference of the discs (8), below the surface of the water (18) and on the downstream side of the disc cluster (2) which, in use, is submerged in fluid (18).

Description

IMPROVEMENTS IN FLAT DISC TURBINE GENERATORS

The present invention relates to improvements in harnessing the movement of water to generate electricity, more specifically using a disc cluster in conjunction with a generator to convert tidal motion into electricity.

The constant rise and fall in sea levels due to the tides is a predictable source of energy, consequently generators that convert tidal motion into electricity exist in many different forms. Attempts to harness the power of the tides have, however, proved inefficient. The marine screw design is the current basis for tidal power generation and such systems have not yet gained wide acceptance as a viable source of mass power generation.

Conventional turbines, such as the marine screw, rely on an impact energy exchange between the fluid and the turbine blades. It is known from the application of a disc cluster that in order to achieve the most energy efficient conversion of fluid movement to rotation of turbine blades, changes in both velocity and direction should be as gradual as possible within the fluid. Accordingly, a disc cluster consists of a series of thin equidistant discs stacked close together in parallel and centrally mounted to a rotatable shaft. A fluid is forced into the discs tangentially at the outer edge such that the fluid passes over and between said discs. The adhesion of the boundary layer of the fluid to the surface of the discs creates a drag force, which combined with the viscous nature of the fluid causes the discs and thus the shaft to rotate. This turbine, invented by Nikola Tesla is described in US Patent Nos. 1,061,142 and 1,061,206.

According to a first aspect of the present invention there is provided a fluid driven turbine generator comprising a rotatable shaft, a plurality of spaced apart parallel discs carried on the shaft so as to be rotationally fast therewith, and power generation means connected to the shaft so as to be rotated thereby, the circular surface of each said disc having a plurality of recesses or dimples formed therein so as to increase the surface area.

A turbine generator in accordance with the first aspect of the invention has the advantage that the increase in the surface area of the discs produced by the dimples increases the energy imparted to the discs by the fluid as it passes across the surface thereof, thereby increasing the efficiency of the system.

Preferably, the dimples are formed in a uniform pattern on each surface of each disc. In particular, the dimples are advantageously arranged in two concentric rings, the outer ring being located proximate to the outer edge of the disc and having dimples of a first diameter and the inner ring having dimples of a second, smaller diameter.

According to a second aspect of the present invention there is provided a fluid driven turbine generator comprising a rotatable shaft, a plurality of spaced apart parallel discs carried on the shaft so as to be rotationally fast therewith, power generation means connected to the shaft so as to be rotated thereby, and a debris removal system for removing debris from between said discs.

Preferably the debris removal system comprises a plurality of nozzles held proximate to and directed towards said discs and connected via a conduit to a pump. The pump operates to draw fluid through the conduit and out through the nozzles in order spray the discs so as to remove debris from the spaces between said discs which is carried therein by the fluid and which would otherwise become stuck, interfering with the flow of fluid. Preferably the source of fluid for the pump is the same as that which drives the movement of the discs. Advantageously, a percentage of the power generated by the turbine is used to power the operation of the pump, it being preferable that the operation of the pump is automatic and occurs at regular predetermined intervals.

According to a third aspect of the present invention there is provided a fluid driven turbine generator comprising a rotatable shaft, a plurality of spaced apart parallel discs carried on the shaft so as to be rotationally fast therewith, power generation means connected to the shaft so as to be rotated thereby, and a plate which extends longitudinally parallel to the shaft across said plurality of discs proximate to the outer surface thereof, said plate extending partially around the circumference of the discs which, in use, will be submerged in the fluid.

A turbine generator in accordance with the third aspect of the invention has the advantage that the plate enables the rotational speed of the shaft to be controlled whilst also providing the discs with an element of protection from debris. Preferably, the plate has a radius of curvature equal to the radius of curvature of the outer edges of the discs. The plate is preferably held in place by means of a bracket and is adjustable so as to vary the separation between the plate and the discs. Furthermore, the length of the plate in the circumferential direction of the discs is such that, in use, the plate is completely submerged in the fluid.

Preferably the fluid used to impart rotational movement to the discs and thus the shaft in order to generate electricity through operation of the alternator is water, be that either freshwater or saltwater.

It will, of course, be understood that the various aspects of the invention are not mutually exclusive and may be utilised in combination.

The discs may be integrally formed with the shaft or may be formed separately therefrom and mounted on the shaft in combination with space elements which locate on either side of each disc in order to maintain the required spacing. In that case, the discs are non-rotatably connected to the shaft, for example by means of a keyway or splines, so that as motion is imparted to the discs by the fluid moving therepast, it is transferred to the shaft.

Preferably buoyancy means are associated with the shaft, in particular carried on a housing member, which float the discs at a predefined degree of immersion within the fluid so as to optimise efficiency. Anchoring means may also be provided which anchor the turbine in place in the fluid flow, the shaft being fastened to the anchoring means so to allow it freely to move up and down relative to the anchoring means with changes in level of the fluid under the action of the buoyancy means.

According to another aspect of the invention there is provided a method of generating electricity, comprising the steps of providing a turbine generator according to at least one of the first to third aspects of the invention, and positioning the turbine in a fluid flow with the shaft substantially perpendicular to the direction of flow and substantially parallel to the surface of the fluid and with the discs partially immersed to less that half their diameter in the fluid.

In a second preferred embodiment of the first aspect of the invention a plurality of uniformly spaced concentric circular grooves provide an alternative to the outer and inner rings of dimples. Similarly, in another preferred embodiment vanes are used as an alternative to dimples and or grooves, the equidistant vanes extending radially inwardly from the outer edge toward but short of the centre of each disc and across said disc surface. Preferably the vanes are substantially rigid and extend radially across approximately half of the diameter of each disc. Advantageously, a combination of dimples, grooves and vanes could be used depending on the application of the system.

In an alternate preferred embodiment of the second aspect of the present invention the pump and conduit arrangement of the debris removal system is replaced by a plurality of arm members which extend between the spaces between adjacent pairs of discs on one side of the shaft, each space having a single arm member associated with each and the arm members being a clearance fit between the discs, the end of each arm, in use, terminating on the downstream side of the shaft and above the level of the fluid. Preferably, the arms extend from and are rigidly attached to a housing which extends across the entire width of the shaft. The arms operate as an alternative method of removing debris from the spaces between the discs.

In order that the invention may be well understood, there will now be described an embodiment thereof, given by way of example, reference being made to the accompanying drawings, in which:

Figure 1 is an exploded end-on view of an apparatus according to the invention, showing the separation of the turbine blades and the water level during use;

Figure 2 is an exploded view of the shaft of Figure I₅ showing the profile of the key means and keyway;

Figure 3 is an exploded end-on view of an apparatus according to the invention, showing the position of the pump, conduit and nozzles used to clean the turbine blades during use;

Figure 4 is a detail perspective view of an apparatus according to the invention showing a pump, conduit and associated nozzles positioned proximate to the turbine blades;

Figure 5 is a detail view of the apparatus of Figure 1, showing the position and shape of the debris guards of the second preferred embodiment;

Figure 6 is a detail view of a turbine blade of Figure 1, showing the position of the recessed dimples and the profile of a turbine blade;

Figure 7 is a detail view of a turbine blade of Figure 1 according to a second preferred embodiment, showing the position of grooves and the profile of a turbine blade; Figure 8 is a detail view of a turbine blade of Figure 1 according to a third preferred embodiment, showing the position of vanes and the profile of a turbine blade;

Figure 9 is a plan view of a turbine blade of Figure I₅ showing the position and curvature of the curved plate and the water level during use; and

Figure 10 is a plan view of the apparatus of Figure 1, showing the shape of the turbine casing with inlet and exhaust points.

Referring to Figures 1 to 10, there is shown a first embodiment of a water- powered generator 1. The generator 1 comprises a disc cluster 2 drivingly connected to a pair of alternators 3 and 4. When water passes through the disc cluster 2, adhesion of the water with the surface of the disc cluster 2 causes the cluster to rotate, which rotation is transferred to the alternators 3, 4 via a geared pulley system 5 in order to generate electricity in a well known manner.

The disc cluster 2 is composed of a plurality of circular discs 8 interleaved with a plurality of spacers 9, adjacent discs being separated by a spacer 9 with the discs 8 and spacers 9 being concentrically mounted on a common shaft 10. The spacers 9 are thin cylindrical collars, as illustrated in Figure 2, whose outer radius is substantially smaller than the radius of the discs 8 so that a space is formed between the radially outer portion of neighbouring discs 8 through which the fluid can pass as described below.

The discs 8 and spacers 9 are non-rotatably coupled to the shaft 10 so as to rotate therewith, and more particularly so that rotational movement imparted to the discs 8 by the fluid is transferred to the shaft 10. In the illustrated embodiment, this is achieved by the shaft 10 having a longitudinally extending spline 12 formed on its outer surface which extends between but terminates short of the ends of the shaft 10 and forms a key member on the shaft 10. Each of the discs 8 and the spacers 9 has a central opening formed therein which is a close tolerance fit with the outer circular surface of the shaft 10 and through which the shaft 10 extends. A notch 13, which is of complementary size and shape to the spline 12 formed on the shaft 10, extends radially outwardly from the central opening so as to form a keyway 13 for receiving the key member 12 of the shaft 10 and hence non-rotatable couple each disc 8 and spacer 9 to the shaft 10. It will, though, be understood that other systems may be used to non-rotatably mount the discs and spacers onto the shaft 10, such as splines, or even integrally forming the discs 8 on the shaft 10. Furthermore, it is not essential to the invention that the spacers 9 being non-rotatably coupled to the shaft and they instead could simply be journal mounted thereon.

As described above, the notch 13 does not extend all the way to the ends of the shaft 10 and instead the ends are left with a circular cross-section and are received in bearings 11 so that the shaft 10 is freely rotatable about its longitudinal axis.

The disc cluster 2 is centrally located on the shaft 10 and extends along a substantial portion thereof. A pair of disc-retaining flanges 14, 15 are positioned on the shaft 10 on either side of the disc cluster 2, are non-rotatably mounted to the shaft 10 and include retaining means such as grub screws for securing them to the shaft 10 against longitudinal movement therealong. The flanges 14, 15 are thereby used to secure the disc cluster 2 in position and to compress the discs 8 together to ensure a uniform spacing.

As shown in Figure 1, a pulley wheel is mounted in a rotationally fast manner on either end of the shaft 10 and a suitable drive belt is used to transfer rotation of the shaft to an electricity generator which operates in a conventional manner which will not be described any further.

The system operates by partially immersing the disc cluster 2 in a moving fluid such as water with the longitudinal axis of the shaft 10 extending substantially parallel to the surface of the water and perpendicular to the direction of flow. The cluster 2 is immersed so that less than half of the circular area of each disc 8 is submerged. In this way, all motion imparted to the discs 8 as the water passes through the cluster 2 is in the same direction. The flow of the water is directed through the spaces between the discs 8 formed by the spacers 9, and as the water moves past the surfaces of the discs 8, the adhesion of the water to the material of the discs 8 causes the discs 8 to move with the water, imparting a rotational movement to the shaft 10.

Figures 6a and 6b show enlarged front and side views of one of the discs 8, from which it can be seen that a series of dimples 26 are formed in the circular faces thereof in order to increase the surface area and hence energy transferred to the discs 8 by the flowing water. In particular, it can be seen that two rings 24, 25 of recessed circular dimples 26 form the surface pattern on both sides of each turbine blade 8 - an outer ring 24 of dimples 26, each having a first diameter surrounding an inner ring 25 of dimples 26 of a smaller diameter, the outer ring 24 being located proximate to the outer edge of each turbine blade 8.

In an alternate preferred embodiment, as shown in Figure 7, the dimples 26 as shown in Figure 6 are replaced by a series of uniformly spaced concentric circular grooves 27 that cover a portion of the surface of each disc 8 and have a centre about the centre of each disc 8.

Similarly, in another preferred embodiment, as shown in Figure 8 vanes 28 are used as an alternative to dimples 26 and or grooves 27. The equidistant vanes 28 extend across the surface of each disc 8 radially inwardly from the outer edge toward but short of the centre of said disc 8.

In order to maintain the required degree of immersion of the disc cluster 2 in the fluid, buoyancy members 16, 17, such as air filled containers, are provided on each end of the assembly, the buoyancy of which are set to ensure that the disc cluster 2 maintains its optimal position relative to the surface of the water as the water level 18 rises and falls, for example due to tidal changes, increases in the volume of water, etc. A retaining ring 19, 20 is also provided on each end of the assembly, each of which hooks over one of a pair of poles 21, 22 which are secured in position within the water flow, for example by being driven into the river bed. Each retaining ring 19, 20 is a loose fit on the outer surface of the pole 21, 22 so that the assembly can freely slide up and down the pole 21, 22 in response to changes in the water level 18 whilst maintaining the assembly in position in the water flow.

As shown in Figure 3, and in more detail in Figure 4, a conduit 29 extends across the top of the disc cluster 2 between the opposing ends of the shaft 10 and more particularly between the upper ends of uprights on which the buoyancy members 16, 17 are carried. At either ends of the conduit 29 are pumps 30, 31 held above the water level 18 with further conduits 32, 33 extending from each pump 30, 31 into water pickups 34, 35 respectively secured beneath the water level 18. Each pump 30, 31 operates to draw water through the conduits 32, 33 and out through nozzles 36 located along the length of conduit 29 in order to spray the discs 8 so as to remove debris which becomes lodged within the disc cluster 2 as the water passes therethrough and which would otherwise interfere with the flow said of water. A percentage of the power generated by the turbine is used to power the operation of the pumps 30, 31. The pumps 30, 31 are automatically timed to operate at regular predetermined intervals.

Referring to Figure 5 a second, alternate preferred embodiment of the apparatus is shown, similarly comprising the majority of components of the first embodiment. In this second embodiment, as in the first, a turbine housing 23 extends across the top of the disc cluster 2 between the opposing ends of the shaft 10 and more particularly between the upper ends of uprights on which the buoyancy members 16, 17 are carried. In contrast to the first embodiment, extending from the housing 23 are a plurality of debris guards 7, one associated and longitudinally aligned with each spacer 9. Each debris guard 7 is a flat plate whose thickness is less than the thickness of each spacer 9 so that it is a clearance bit is the longitudinal space between neighbouring discs 8. Each debris guard 7 is rigidly fastened to the housing 23 and is formed with an arm portion 7a which extends away from the housing 23 and a spatula head portion 7b formed on the end of each arm portion 7a. Each debris guard 7 occupies the space between one pair of neighbouring discs 8 on the side of the shaft 10 which, in use, will be the downstream side with regard to the flow direction of the fluid, and extends below the level of the shaft 10 to the surface of the water, but does not actually immerse therein.

The debris guards operate to remove from between the discs any debris which becomes lodged within the disc cluster as the water passes therethrough.

In order to control the speed of rotation of the disc cluster 2, a curved plate 6 is positioned proximate to the outer surface of the disc cluster 2 below the surface of the water and on the downstream side of the cluster 2 as shown in Figure 9. The plate 6 has an arcuate cross section and extends longitudinal along the whole length of the disc cluster 2, with a surface curvature equal to the curvature of the outer surface of the disc cluster 2. The plate 6 is positioned at the base of the disc cluster 2, parallel to the shaft 10, wholly beneath the water level 18 and away from the turbine blades 8 so as to form a conduit for the flowing water between the curved plate 6 and said turbine blades 8. In use, to increase the rotational speed of the turbine blades 8 the curved plate 6 is moved toward the perimeter of the turbine blades 8. Similarly, to decrease the rotational speed of the turbine blades 8 the curved plate 6 is moved away from the perimeter of the turbine blades 8. During movement, the curved plate 6 is maintained parallel to the shaft 10. Controlled movement of the curved plate 6 is achieved by adjustment of an arm 37 which enables the repositioning of a bracket 38, as shown in Figure 9.

Finally, Figure 10 shows a plan view of the turbine casing 39. A narrowing pipe 40 is used to increase the speed of the water as in approaches the disc cluster 2.

It will be appreciated that the dimensions of the turbine blades 8 and spacers 9 can be altered depending of the viscosity of the fluid directed to pass therebetween (for example salt water or fresh water). Similarly, the surface of the turbine blades 8 may be modified for alternate preferred embodiments in order to achieve the optimum topography for that particular embodiment. This could be achieved, for example, with a combination of dimples, grooves, vanes or ridges, etc. Also, in a further preferred embodiment a flywheel could be mounted to the shaft 10 in order to improve performance.

Thus, the disc cluster 2 can be used to generate electricity by efficiently harnessing the energy of flowing water, without experiencing the fluid energy losses associated with the impact dependent marine screw design. The adhesion of the boundary layer of the fluid to the surface of the turbine blades 8 creates a drag force, which causes the blades 8 to rotate, thus the surface topography, diameter and separation of the blades 8 can be optimised for each application of the invention. The debris guards 7 maintain the efficient running of the system and the curved plate 6 provides a means to control the rotational speed of the turbine blades 8.

Claims

1. A turbine generator (1), comprising: a rotatable shaft (lθ); a plurality of spaced apart parallel discs (8) carried on the shaft (10) so as to be rotationally fast therewith; and power generation means connected to the shaft (10) so as to be rotated thereby; wherein the circular surface of each disc (8) has a plurality of recesses, dimples (26), grooves (27), vanes (28), projections or other surface topography formed therein so as to increase the surface area.

2. A turbine generator (1) according to Claim 1, wherein the recesses or dimples (26) are formed in a uniform pattern on each surface of each disc (8).

3. A turbine generator (1) according to Claim 2, wherein the uniform pattern of recesses or dimples (26) comprises two concentric rings.

4. A turbine generator (1) according to Claim 3, wherein the two concentric rings are comprised of an outer ring (24) located proximate to the outer edge of the disc (8) and having dimples (26) of a first diameter, and an inner ring (25) proximate to the centre of the disc (8) having dimples (26) of a second, smaller diameter.

5. A turbine generator (1) according to any of the preceding claims, wherein the grooves (27) are uniformly spaced concentric circles.

6. A turbine generator (1) according to any of the preceding claims, wherein the vanes are uniformly spaced and extend radially inwardly from the outer edge toward but short of the centre of each disc (8) and across said disc (8) surface.

7. A turbine generator (1) according to Claim 6, wherein the vanes are substantially rigid and extend radially across approximately half of the diameter of each disc (8).

8. A turbine generator (1) according to any of the preceding claims, wherein the discs (8) are integrally formed with the shaft (10).

9. A turbine generator (1) according to any of claims 1 to 7, wherein the discs (8) are formed separately from the shaft (10) and mounted thereon in combination with space elements (9) which locate on either side of each disc (8) in order to maintain the required spacing.

10. A turbine generator (1) according to any of the preceding claims, wherein buoyancy means (16,17) is associated with the shaft (10).

11. A turbine generator (1) according to Claim 10, wherein the buoyancy means (16,17) is carried on a housing member, said housing member floating the discs (8) at a predefined degree of immersion within the fluid (18) so as to optimise efficiency.

12. A turbine generator (1) according to Claim 11, wherein anchoring means is provided which anchors the turbine in place in the fluid flow, the shaft (10) being fastened to the anchoring means so to allow it freely to move up and down relative to the anchoring means with changes in level of the fluid (18) under the action of the buoyancy means (16,17).

13. A turbine generator (1) according to any of the preceding claims, wherein a narrowing pipe (40) upstream of the turbine channels water (18) toward the discs (8) of the generator (1) and thus increases the speed of the water (18) as it approaches said discs (8).

14. A turbine generator (1) according to any of the preceding claims, further including a debris removal system for removing debris from between the discs (8).

15. A turbine generator ( 1 ), comprising: a rotatable shaft (10); a plurality of spaced apart parallel discs (8) carried on the shaft (10) so as to be rotationally fast therewith; power generation means connected to the shaft (10) so as to be rotated thereby; and a debris removal system for removing debris from between the discs (8).

16. A turbine generator (1) according to claim 14 or 15, wherein the debris removal system comprises a plurality of nozzles (36) located proximate to and directed towards the discs (8) and connected via a conduit (29) to a pump (30, 31), the pump (30, 31) drawing fluid (18) through the conduit (29) and out through the nozzles (36).

17. A turbine generator (1) according to Claim 16, wherein the source of fluid (18) for the pump (30, 31) is the same as that which, in use, drives the movement of the discs (8).

18. A turbine generator (1) according to Claim 17, wherein power generated by the turbine is used to power the operation of the pump (30, 31).

19. A turbine generator (1) according to Claim 18, further comprising control means configured to operate the pump (30, 31) automatically at regular predetermined intervals.

20. A turbine generator (1) according to claim 14 or 15, wherein the debris removal system comprises a plurality of arm members (7), each of which extends into the space between an adjacent pair of discs (8) on one side of the shaft (10), each space having a single arm member (7) associated with it and the arm members (7) being a clearance fit between the discs (8), the end of each arm (7), in use, terminating on the downstream side of the shaft (10) and above the level of the fluid (18).

21. A turbine generator (1) according to Claim 20, wherein the arms (7) extend from and are rigidly attached to a carrier which extends across the entire width of the shaft (10).

22. A turbine generator (1) according to any of the preceding claims, further including a plate (6) which extends longitudinally parallel to the shaft (10) across the plurality of discs (8) proximate to the outer surface thereof; wherein said plate (6) extends partially around the circumference of the discs (8), below the surface of the water (18) and on the downstream side of the disc cluster (2) and which, in use, is submerged in fluid (18).

23. A turbine generator (1), comprising: a rotatable shaft (10); a plurality of spaced apart parallel discs (8) carried on the shaft (10) so as to be rotationally fast therewith; power generation means connected to the shaft (10) so as to be rotated thereby; and a plate (6) which extends longitudinally parallel to the shaft (10) across the plurality of discs (8) proximate to the outer surface thereof; wherein said plate (6) extends partially around the circumference of the discs (8), below the surface of the water (18) and on the downstream side of the disc cluster (2) and which, in use, is submerged in fluid (18).

24. A turbine generator (1) according to claim 22 or 23, wherein the plate (6) has a radius of curvature equal to the radius of curvature of the outer edges of the discs (8).

25. A turbine generator (1) according to Claim 24, wherein the plate (6) is held in place by means of a bracket (38) and is adjustable so as to vary the separation between the plate (6) and the discs (8).

26. A turbine generator (1) according to Claim 25, wherein the length of the plate (6) in the circumferential direction of the discs (8) is such that, in use, the plate (6) is completely submerged in the fluid (18).

27. A turbine generator (1) according to Claim 26, wherein the plate is maintained parallel to the shaft (10).

28. A method of generating electricity, comprising the steps of providing a turbine generator (1) according to any of the preceding claims and positioning the turbine (1) in a fluid flow with the shaft (10) substantially perpendicular to the direction of flow and substantially parallel to the surface of the fluid (18) and with the discs (8) partially immersed to less than half their diameter in the fluid (18).

29. A method of controlling the rotational velocity of a turbine generator (1), comprising the steps of providing a turbine generator (1) according to any of claims 22 to 27, positioning the turbine (1) in a fluid flow with the shaft (10) substantially perpendicular to the direction of flow and substantially parallel to the surface of the fluid (18) and with the discs (8) partially immersed to less than half their diameter in the fluid (18), and varying the radial distance of the curved plate (6) from the perimeter of said discs (8) in order to control the rotational speed of the discs (8).