GB2498973A

GB2498973A - Turbine scoop formed from a plurality of spaced flat plates

Info

Publication number: GB2498973A
Application number: GB1201733.1A
Authority: GB
Inventors: Mark Bloomfield
Original assignee: Individual
Current assignee: Individual
Priority date: 2012-02-01
Filing date: 2012-02-01
Publication date: 2013-08-07
Also published as: GB201201733D0

Abstract

A turbine, eg a wind, steam, water, hydro or tidal turbine, comprises a scoop 1 rotatable about an axis 3 in response to a flow of fluid toward the turbine in a direction substantially at a right angle to the axis 3, the scoop 1 being formed from a plurality of substantially flat plates 5 disposed at right angles to the axis 3 and spaced apart from one another such that fluid may pass between the plates 5, wherein the plates 5 are configured to provide the scoop with a first side 9 and a second side 11, the second side being convex 11. The convex side 11 may be enclosed by an outer wall. Each plate 5 may be shaped as one half of the Taijitu symbol, or three-lobed, and may be offset rotationally about the axis 3 with respect to adjacent plates such that the first side 9 is helical. The plates may have an axial bore and through-hole(s) 13. Aerofoils (435, fig.11) may be connected to upper and lower portions of the scoop to assist its rotation.

Description

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BOUNDARY LAYER TURBINE

The present invention relates to turbines. In particular, but not exclusively, to wind, steam, water, hydro and tidal turbines, although other fluid turbines are also envisaged, such as oil, mud or plasma.

A turbine according to the present invention could be used as a pump, for instance a water pump, as a flywheel, for electrical power generation, or for air conditioning, for instance by directly providing a cool air stream.

Turbines of the type described herein are often referred to as vertical axis turbines. However, it is to be understood that the axis of such turbines need not be vertical. In fact, the term vertical axis wind turbine merely refers to the angle of incidence of the working fluid being substantially at right angles to the rotational axis of the turbine. In contrast, in a horizontal axis turbine, the working fluid is incident substantially parallel to the rotational axis of the turbine.

One type of vertical axis turbine known to those working in the field is the Savonius turbine. Savonius turbines are drag-type devices that include scoops configured to rotate about an axis. The scoops experience more drag in one rotational direction than the opposing direction. Therefore, fluid flow toward a Savonius wind turbine will cause the scoops to rotate about the turbine axis.

In order to attain highest economy, the changes in speed and direction of movement of the working fluid should be as gradual as possible.

According to a first aspect of the present invention, there is provided a turbine, comprising a scoop configured to rotate about an axis in response to a flow of fluid toward the turbine in a direction substantially at a right angle to the axis, the scoop formed from a plurality of substantially flat plates disposed at right angles to the axis and spaced apart from one another such that fluid may pass between the plates, wherein the plates are configured to provide the scoop with a first side and a second side, the second side being convex.

A scoop may be defined as having an internal volume accessible to a fluid and, when present in a fluid flow in a first direction, the scoop is configured to experience drag of a magnitude much greater than the drag experienced when present in a fluid flow of the same magnitude, but in an opposing direction. For instance, the drag experienced from a fluid flow in a first direction may be greater than the drag experienced from a fluid

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flow in the opposite direction by a factor in the range between 2 and 10, for instance 2, 4, 5, 6, 7, 8, 9 or 10, and in particular in the range between 2.5 and 4.5.

The first side of the scoop may be a fluid catching side. The second side of the scoop may be a fluid shedding side. The first side of the scoop may be concave. The 5 first side of the scoop may be convex. The first side of the scoop, when a fluid flow is incident thereon, may be configured to experience drag of a magnitude much greater than the drag experienced when a fluid flow of the same magnitude, is incident on the second side of the scoop.

The plates may be substantially flat. In particular, they may have a thickness 10 substantially less than their length and breadth. For instance, the plates may be made from sheet material, such as metal, plastics of composite materials, and may have a thickness of between 0.5mm and 10cm, in particular between 2mm and 8cm, more particularly between 1cm and 5cm, and may have a dimension within a plane of the plate of between 10cm and 15m, or 20cm and 5m, in particular between 50cm and 2.5m, for 15 instance 80cm; however, larger diameters are envisaged. In any case, the dimensions of the plates may in part be determined by the material used in their construction, in that the rigidity of the plates when rotating at speed in various different working fluids will need to be considered. The plates may have two opposing parallel faces of substantially the same shape, and at least one other face forming a perimeter and joining the two opposing 20 parallel faces.

Accordingly, fluid flowing into contact with the first side of the scoop in a direction substantially at a right angle to the axis may impart a force on the at least one scoop in the direction of motion of the fluid. In particular, the fluid may act against the face(s) forming the perimeter of each plate. Furthermore, fluid flowing between the 25 plates of the scoop may act to reduce an initial impulse imparted to the scoop, and at the same time may gradually accelerate the scoop over a longer period of time, due to the formation of a boundary layer between the plates. Thus, a higher economy may be attained due to a more gradual change in the speed and direction of movement of the working fluid. By carefully choosing the spacing of the plates, a higher economy may be 30 attained. The plates may be spaced apart by any suitable distance. However, the selection of that distance depends on various factors, including: the size of the plates, the working fluid (viscosity and speed), and turbulence. The plates may be spaced apart by a distance

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of between 1mm and 10cm, in particular between 2mm and 2cm (for instance, 2mm), or alternatively between 1cm and 5cm.

Each plate may be identical to each other plate. However, arrangements are envisaged in which some or all of the plates differ from each other plate.

5 The plates may be configured to be mounted on a shaft, for rotation about the axis. For instance, each plate may be provided with an axial bore through which a shaft can be passed. Alternatively, the plates may be attached to each other and free to rotate about the axis by virtue of a bearing arrangement external to the plates.

The scoop may further comprise an outer wall enclosing the second side of the 10 scoop. Each plate may include a hole therethrough. The holes may be configured to form a passage for fluid flow in a direction substantially parallel to the axis.

In this way, the outer wall may prevent the working fluid from being lost through the second side of the scoop, after entering the scoop through the first side, and instead may direct it through one of the holes in the adjacent plates. The fluid may continue to 15 move through the holes in successive plates before exiting the turbine at either one or both axial ends. In the same way, the outer wall may prevent the working fluid from entering the scoop from the second side of the scoop.

The outer wall may be a barrier to the fluid. The outer wall may be formed by a raised curved wall section of each plate, forming a seal with the plate above, in the vicinity 20 of the second side. Alternatively, the outer wall may be overlaid separately. The outer wall may be a single-piece skin.

The holes may be circular in form, although other forms such as triangular or trapezoidal are envisaged.

Each plate may be rotationally offset about the axis with respect to adjacent 25 plates, such that the first side has a substantially helical form.

That is, each plate may be fixed to an adjacent plate in a rotationally displaced position, about the axis, relative to the adjacent plate. The amount of rotational displacement may be constant between plates, or may vary along the axis of the turbine.

For instance, if each plate is identical to each other plate, then two plates may be 30 fixed together such that one of the plates leads the other in a rotational sense about the axis. For example, a point on one plate may be located at a first angle about the axis, and a corresponding point on a second plate, fixed to the first plate, may be located at a second angle (differing from the first angle by a number of degrees, or a fraction of a

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degree, such as between 0.5 degrees and 10 degrees, in particular between 3 degrees and 6 degrees, for instance, 3, 4, 5 or 6 degrees), a corresponding point on a third plate, fixed to the second plate, may be located at a third angle (differing from the second angle by the same number of degrees, or a fraction of a degree), and so on.

5 In this way, fluid that is unable to pass between the plates, due to an area of restricted volume caused by the boundary layer, may be neither stopped nor reflected, but rather may be deflected around the helical path. Thus, a higher economy may be attained due to a more gradual change in the speed and direction of movement of the working fluid.

10 Furthermore, by forming a scoop of helical form, the turbine may become self-

starting.

In addition, stability of the turbine may be maintained by reducing asymmetric distribution of weight about the axis.

The hole in each plate may be rotationally offset about the axis with respect to 15 adjacent holes, such that the passage formed by the holes has a substantially helical form.

That is, each hole may be located in the turbine in a rotationally displaced position, about the axis, relative to an adjacent plate. The amount of rotational displacement may be constant between plates, or may vary along the axis of the turbine.

For example, a hole in one plate may be located at a first angle about the axis, and 20 a hole in a second plate, fixed to the first plate, may be located at a second angle (differing from the first angle by a number of degrees, or a fraction of a degree, such as between 0.5 degrees and 10 degrees, in particular between 3 degrees and 6 degrees, for instance, 3, 4, 5 or 6 degrees), a corresponding hole in a third plate, fixed to the second plate, may be located at a third angle (differing from the second angle by the same number of degrees, 25 or a fraction of a degree), and so on.

In this way, the fluid may move through the holes in successive plates along a helical path before exiting the turbine at either or both axial ends.

The holes may be centred a predetermined distance from the axis. The predetermined distance from the axis may vary along the axis of the turbine. In an 30 alternative embodiment, the holes may be centred on the axis.

Each plate may comprise tubercles disposed along a face forming a perimeter of the plate and defining the first side of the scoop.

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The tubercles may be in the form of nodules, pimples, warts, projections, or protuberances. The tubercles may be spherical, ellipsoidal, conical or otherwise shaped in profile.

In this way, initial drag associated with air incident upon the plates may be 5 reduced, affecting a more gradual change in the speed and direction of the working fluid, thereby achieving a higher efficiency of the turbine.

In alternative embodiments, the face forming a perimeter of each plate and defining the first side of the scoop may be flat, at right angles to the planar surface of the plate, box-like, chamfered, smooth, bull-nosed or rounded in profile. 10 The turbine may further comprise irregularities in the turbine's surface.

The irregularities may be in the form of small cavities, depressions or dimples, such as those found on a golf ball. The irregularities may be mushroom-shaped. The irregularities may comprise openings in the turbine's surface that lead to hollows, larger than the openings. The irregularities may be on the second side of the scoop. The 15 irregularities may be in the inner and/or outer surface of the outer wall. The irregularities may be in the surface of the plates.

In this way, the Coanda effect may be used to improve the efficiency of the turbine.

Each plate may be shaped as one half of the Taijitu symbol.

20 That is, the perimeter of each plate could be described as two equal oppositely oriented semi-circular arcs of radius 5 units joined at their ends to form an 'S' shape, plus a semi-circular arc of radius 10 units joining the free ends of the 'S' shape. Optionally, the hole through each plate may be circular, and centred on the centre of one of the semicircular arcs of radius 5 units. As a further option, the hole may be 1 unit in radius. 25 Other shapes are also envisaged. In various embodiments, each plate may be shaped to have a convex edge and a concave edge.

The turbine may comprise at least or only two scoops, disposed symmetrically about the axis and configured to rotate about the axis together, the scoops formed from the plurality of plates, wherein the plates are configured to provide each scoop with a first 30 side and a second side. The second side may be convex. The first side may be concave.

Thus, the turbine may become self-starting, or improve its self-starting ability.

The turbine may comprise three or more scoops configured to rotate about the axis together.

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Each scoop may be identical to each other scoop. For instance, each scoop may be of the same size, shape and/or form. Each scoop may be of the same construction. Each scoop may be located the same distance from the axis. Each scoop may provide the same rotation generating effect for a given incident fluid flow. Alternatively, the scoops 5 may differ from one another in at least one way.

Each plate may include more than one hole therethrough for the passage of fluid in a direction substantially parallel to the axis. The holes may be disposed symmetrically about the axis. The number of holes may be equal to the number of scoops. The number of holes may be equal to a multiple of the number of scoops, such as two or 10 three times. Each plate may comprise three of more holes therethrough for the passage of fluid in a direction substantially parallel to the axis.

Each plate may be substantially circular.

In this way, the appearance of the turbine may be improved by limiting the apparent rotation of the turbine in operation. The turbine may appear to an observer to 15 be cylindrical. The turbine may appear to an observer to be stationary, even when it is rotating.

Furthermore, the surface area of the turbine over which fluid may act may be increased, for a given size of turbine, so as to increase efficiency.

Each disc may be circular. The disc may be configured to rotate about the axis 20 through its geometric centre. In this way, stability of the turbine may be maintained by reducing asymmetric distribution of weight about the axis.

Each plate may be integrally formed, such that the disc may be a single unit. Alternatively, each disc may be constructed from multiple components.

The turbine may comprise at least two aerofoils disposed symmetrically about the 25 axis. Each aerofoil may be substantially parallel to the axis. The aerofoils may be configured to rotate about the axis together in response to a flow of fluid toward the turbine in a direction substantially at a right angle to the axis. Each aerofoil may be directly or indirectly attached to the scoop, so as to rotate about the axis with the scoop.

Where reference is made to aerofoils, it is envisaged that hydrofoils or similar 30 blade-lift devices could be used, depending on the fluid for which the turbine has been designed.

Each aerofoil may be rigidly coupled to the scoop. Each aerofoil may be fixed to the scoop. The aerofoils and the scoop may rotate together.

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In this way, fluid flow incident on the aerofoils in a direction substantially at a right angle to the axis causes the turbine to rotate.

The turbine may comprise two, three, or more aerofoils.

The at least two aerofoils may be straight, curved, helical or any other shape 5 common in conventional Darrieus Turbine design.

The at least two aerofoils may be mounted such that it/they may rotate about its/their own vertical axis/axes in order to vary the pitch of the blades.

The aerofoils may be attached to the scoop at the axial ends of the turbine.

The turbine may be optimised for a specific fluid and/or a specific fluid flow 10 speed. For instance, the turbine may be optimised for operation with air or water as the fluid. The turbine may be optimised to operate at wind speeds between force 3 and force 7, for instance, between force 4 and force 6. The turbine may be optimised to operate at air speeds between 3ms4 and 17ms4, and in particular between 5.5ms4 and 14ms4. The turbine may be optimised to operate at air speeds of 6ms4.

15 The diameter of the plates may vary along the axis of the turbine. The diameter may be a measure of the extent of a plate substantially across its plane.

In this way, different plates may be optimised for different fluid flow speeds. For instance, the diameter of the plates may be 80cm for air flowing at 6ms4 (Force 4).

The diameter of the discs located at each axial end of the turbine may be larger 20 than the diameter of the discs located in between. The variation of diameter of the discs with distance along the axis may be continuous and may be smooth. For instance, the variation of diameter of the discs with distance along the axis may be a harmonic function. However, alternative functions are envisaged, such as conics.

The diameter of the holes may vary along the axis of the turbine. 25 In this way, the holes may be optimised for different fluid flow speeds. For instance, the diameter of the holes may be 4cm for air flowing at 6ms4 (Force 4).

For instance, the diameter of central holes may vary from disc to disc. The diameter of the central holes in the discs located at each axial end of the turbine may be larger than the diameter of the central holes in the discs located in between. The 30 variation of diameter of the central holes of the discs with distance along the axis may be continuous and may be smooth. For instance, the variation of diameter of the central holes of the discs with distance along the axis may be a harmonic function. However, alternative functions are envisaged, such as conics.

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The plates may be spaced apart from one another by a distance that varies along the axis of the turbine.

In this way, different pairs of plates may optimise the boundary layer effect for different fluid flow speeds. For instance, the spacing of the plates may be 2mm for air 5 flowing at 6ms4 (Force 4).

The spacing of each plate from adjacent plates at each axial end of the turbine may be larger than the spacing of each plate from adjacent plates in between. The variation of spacing of each plate from adjacent plates with distance along the axis may be continuous and may be smooth. For instance, the variation of spacing of each plate from 10 adjacent plates with distance along the axis may be a harmonic function. However, alternative functions are envisaged, such as conics.

The turbine may further comprise guide ribs disposed on an internal perimeter of each hole, for guiding flow of fluid within the passage.

In this way, fluid flow through the hole may be encouraged to form a vortex 15 within the passage formed by the holes. The guide ribs may perform a rifling effect. The guide ribs may be projections having a profile substantially the same as one half of a crescent. There may be one, two, three or more guide ribs per hole. The guide ribs may be substantially prism shaped, having their prism axis parallel to the axis, and a prism cross section substantially the same as one half of a crescent. However, other profiles are 20 envisaged.

The turbine may further comprise a volute truncated cone disposed at an end of the passage, and may further comprise a cone disposed at an opposing end of the passage.

A cone may be provided at a first end of the passage, and may have a flat circular base, a conic axis passing through the centre of the base at a right angle thereto, and/or 25 an apex located on the conic axis. The cone may be orientated such that the base lies in or parallel to the plane of one of the plates, and/or the apex extends into the passage. The cone may be connected to a plate by connecting rods, or some other means.

A volute truncated cone may be provided at a second end of the passage, and may have a curved external wall, an open-ended flat circular base, an open-ended flat circular 30 top, and/or a truncated conic axis passing through the centre of the open-ended base and the open-ended top. The volute truncated cone may be oriented such that the open-ended top lies in or parallel to the plane of one of the plates. The volute truncated cone

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may be connected to a plate by a solid screen, or some other means. The solid screen may be an extension of the plate to which the volute truncated cone is connected.

A vortex may be created inside the passage due to the rotation of the scoop. Relatively warm, less dense fluid may circulate around the outside of the vortex.

5 Relatively cool, more dense fluid may circulate around the inner portion of the vortex. The fluid circulating around the outside of the vortex may be allowed to escape the passage via the end that includes the cone. The fluid circulating around the inner portion of the vortex may be allowed to escape the passage via the end that includes the volute truncated cone. In this way, a vortex present in the passage may be split into a warm, 10 rarefied stream and a cool, dense stream. These exhaust streams could be used directly for heating or cooling. Water, which is densest at 4 degrees centigrade, may be split by density alone, and not temperature.

The turbine may further comprise an exhaust pipe coupled to an end of the passage, or to an end of each passage, and angled to provide additional rotational thrust 15 to the turbine.

In some embodiments, there may be an exhaust pipe coupled to each end of the passage(s) and at least one of the exhaust pipes may be angled to provide rotational thrust to the turbine. The exhaust pipe may include an angle of 90 degrees to direct fluid exiting the passage at right angles to the axis.

20 The plurality of plates may be manufactured as a single unit, or may be manufactured as individual units and coupled together. Each plate may include a raised portion that enables correct spacing of the plates. Each plate may include at least one protruding locator that allows correct alignment of the plates, so that the external profile of the turbine may be closely controlled. Each plate may include attachment holes 25 therethrough for enabling rigid connection of the plates together, for instance via a nut and bolt arrangement, or similar.

The turbine may further comprise a bearing arrangement to allow for smooth rotation of the turbine about the axis. The bearing arrangement may be a magnetic bearing arrangement. The bearing arrangement may be a bearing allowing rotation of a 30 central shaft. The bearing arrangement may comprise a circular platform having bearings disposed regularly around a perimeter thereof. In this way, load may be distributed amongst a plurality of bearings leading to improved reliability and lifespan of the turbine.

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The turbine may include an electrical power generator. For instance, the turbine may include permanent magnets and electrical wires.

The plates disposed at the axial ends of the turbine may have a specially defined shape. For instance, the plates disposed at one axial end of the turbine may be 5 hemispherical, of truncated cone form, or have an elliptical cross-section. Other shapes of the plates disposed at the axial ends of the turbine are envisaged.

A turbine according to the invention may comprising at least two aerofoils disposed symmetrically about an axis and each substantially parallel to the axis, and configured to rotate about the axis together in response to a flow of fluid toward the 10 turbine in a direction substantially at a right angle to the axis; and a plurality of substantially flat circular plates disposed at right angles to the axis and attached to the at least two aerofoils, so as to rotate about the axis with the at least two aerofoils, the plates being centred on the axis and spaced apart from one another such that fluid may pass between the plates; wherein each plate includes a central hole therethrough, the holes 15 being configured to form a passage for fluid flow in a direction substantially parallel to the axis.

In this way, fluid flow incident on the aerofoils in a direction substantially at a right angle to the axis causes the plates to rotate in their respective flat planes about their respective centres. Fluid flowing between the plates is accelerated by a boundary layer 20 effect into a spiral path toward the centre of the plates. Fluid then enters a central passageway defined by the holes in each circular plate. The spiralling fluid forms a vortex within the central passageway. The fluid may then exit the turbine along the axis.

The turbine may comprise two or three aerofoils. The at least two aerofoils may be straight, curved, helical or any other shape common in conventional Darrieus Turbine 25 design. The at least two aerofoils may be mounted such that the turbine may rotate about its own vertical axis in order to vary the pitch of the blades. The aerofoils may be coupled to the plurality of circular plates at the axial ends of the turbine.

The above and other characteristics, features and advantages of the present invention will become apparent from the following detailed description, taken in 30 conjunction with the accompanying drawings, which illustrate, by way of example, the principles of the invention. This description is given for the sake of example only, without limiting the scope of the invention. The reference figures quoted below refer to the attached drawings.

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Figure 1 is a perspective view of a part of a turbine arrangement according to a first embodiment of the invention.

Figure 2 is a perspective view of the path traced out by an internal passageway of the turbine arrangement according to the first embodiment of the invention.

5 Figure 3 is a top plan view of a plate according to the first embodiment of the invention.

Figure 4 is a perspective view of a plate according to the first embodiment of the invention.

Figure 5 is side plan view of a plate according to the first embodiment of the 10 invention.

Figure 6 is a perspective view of a part of a turbine arrangement according to a second embodiment of the invention.

Figure 7 is a top plan view of a plate according to the second embodiment of the invention.

15 Figure 8 is a perspective view of a part of a turbine arrangement according to a third embodiment of the invention.

Figure 9 is a top plan view of a plate according to the third embodiment of the invention.

Figure 10 is a perspective view of a part of a turbine arrangement according to a 20 fourth embodiment of the invention.

Figure 11 is a perspective view of a part of a turbine arrangement according to a fifth embodiment of the invention.

Figure 12 is a cutaway perspective view of a part of a turbine arrangement according to a sixth embodiment of the invention.

25 The present invention will be described with respect to particular embodiments and with reference to certain drawings but the invention is not limited thereto but only by the claims. The drawings described are only schematic and are non-limiting. In the drawings, the size of some of the elements may be exaggerated and not drawn to scale for illustrative purposes. The dimensions and the relative dimensions do not correspond to 30 actual reductions to practice of the invention.

Furthermore, the terms first, second, third and the like in the description and in the claims, are used for distinguishing between similar elements and not necessarily for describing a sequence, either temporally, spatially, in ranking or in any other manner. It is

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to be understood that the terms so used are interchangeable under appropriate circumstances and that the embodiments of the invention described herein are capable of operation in other sequences than described or illustrated herein.

Moreover, the terms top, bottom, over, under and the like in the description and 5 the claims are used for descriptive purposes and not necessarily for describing relative positions. It is to be understood that the terms so used are interchangeable under appropriate circumstances and that the embodiments of the invention described herein are capable of operation in other orientations than described or illustrated herein.

It is to be noticed that the term "comprising", used in the claims, should not be 10 interpreted as being restricted to the means listed thereafter; it does not exclude other elements or steps. It is thus to be interpreted as specifying the presence of the stated features, integers, steps or components as referred to, but does not preclude the presence or addition of one or more other features, integers, steps or components, or groups thereof. Thus, the scope of the expression "a device comprising means A and B" should 15 not be limited to devices consisting only of components A and B. It means that with respect to the present invention, the only relevant components of the device are A and B.

Reference throughout this specification to "one embodiment" or "an embodiment" means that a particular feature, structure or characteristic described in connection with the embodiment is included in at least one embodiment of the present 20 invention. Thus, appearances of the phrases "in one embodiment" or "in an embodiment" in various places throughout this specification are not necessarily all referring to the same embodiment, but may refer to different embodiments. Furthermore, the particular features, structures or characteristics of any embodiment or aspect of the invention may be combined in any suitable manner, as would be apparent to one of 25 ordinary skill in the art from this disclosure, in one or more embodiments.

Similarly, it should be appreciated that in the description of exemplary embodiments of the invention, various features of the invention are sometimes grouped together in a single embodiment, figure, or description thereof for the purpose of streamlining the disclosure and aiding in the understanding of one or more of the various 30 inventive aspects. This method of disclosure, however, is not to be interpreted as reflecting an intention that the claimed invention requires more features than are expressly recited in each claim. Rather, as the following claims reflect, inventive aspects lie in less than all features of a single foregoing disclosed embodiment. Thus, the claims

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following the detailed description are hereby expressly incorporated into this detailed description, with each claim standing on its own as a separate embodiment of this invention.

Furthermore, while some embodiments described herein include some features 5 included in other embodiments, combinations of features of different embodiments are meant to be within the scope of the invention, and form yet further embodiments, as will be understood by those skilled in the art. For example, in the following claims, any of the claimed embodiments can be used in any combination.

In the description provided herein, numerous specific details are set forth. 10 However, it is understood that embodiments of the invention may be practised without these specific details. In other instances, well-known methods, structures and techniques have not been shown in detail in order not to obscure an understanding of this description.

In the discussion of the invention, unless stated to the contrary, the disclosure of 15 alternative values for the upper or lower limit of the permitted range of a parameter, coupled with an indication that one of said values is more highly preferred than the other, is to be construed as an implied statement that each intermediate value of said parameter, lying between the more preferred and the less preferred of said alternatives, is itself preferred to said less preferred value and also to each value lying between said less 20 preferred value and said intermediate value.

The use of the term "at least one" may, in some embodiments, mean only one.

The invention will now be described by a detailed description of several embodiments of the invention. It is clear that other embodiments of the invention can be configured according to the knowledge of persons skilled in the art without departing 25 from the true spirit or technical teaching of the invention, the invention being limited only by the terms of the appended claims.

Figure 1 shows a part of a turbine arrangement according to a first embodiment of the present invention. A scoop 1 is shown having an axis 3 (shown as a dotted line) about which the scoop 1 is configured to rotate. The scoop 1 comprises a plurality of 30 substantially flat plates 5, disposed at right angles to the axis and spaced apart from one another such that fluid may pass between the plates through gaps 7. The scoop 1 has a concave side 9 and a convex side 11. Convex side 11 comprises an outer wall.

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Each plate is shaped as one half of the Taijitu symbol. Each plate includes a circular hole 13 therethrough.

Each plate comprises an axial bore 15 through which a shaft (not shown) can be passed.

5 The plates 5 are substantially identical to each other; however, a top plate 17 is provided which differs from the other plates, as will be discussed below. The face forming a perimeter of each plate 5, defining the concave side 9 of the scoop 1 (adjacent the gaps 7), is flat.

Each plate 5 is fixed to an adjacent plate 5 in a rotationally displaced position 10 about the axis, relative to the adjacent plate 5. The arrangement shown comprises thirty-seven plates, each displaced by less than 5 degrees, such that the top plate 17 is rotationally displaced by 180 degrees relative to the bottom plate. Accordingly, the concave side 9 is helical in form. However, more plates could be added to the bottom of the plurality of plates in order to extend the helical concave side 9 around by more than 15 180 degrees.

Cavities 19 are shown in the outer wall of convex side 11. The cavities 19 are substantially mushroom-shaped in cross-section. The cavities act via the Coanda effect to improve the efficiency of the turbine.

Figure 2 shows the passage 21 formed by the holes 13 between the upper face of 20 the top plate 17 and the lower face of the bottom plate 5 of the first embodiment (shown in figure 1). The perimeters of the upper face of the top plate 17 and the lower face of the bottom plate 5 are shown, but the plates 5, 17 themselves are not shown. The outline of five of the holes 13 are indicated along the passage 21. The remaining holes have been omitted. Each hole 13 is located in a rotationally displaced position, about the axis, 25 relative to an adjacent plate. The passage 21 describes a substantially helical path around the axis, and is shown in dotted lines.

Figure 3 shows a top plan view of one of the plates 5 of the first embodiment (shown in figure 1). The outer wall in convex side 11 is formed by a raised curved wall section 23, configured to form a seal with an adjacent plate 5 above.

30 Guide ribs 25 are disposed on the internal perimeter of the hole 13. The guide ribs 25 are substantially prism shaped, having their prism axis parallel to the axis 3, and a prism cross section substantially the same as one half of a crescent.

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Top plate 17 differs from the plates 5 in that it does not include a raised curved wall section 23.

Figure 4 shows a perspective view of the plate 5 of figure 3.

Figure 5 is a side plan view of the plate 5 of figure 3, as seen looking toward the

5 gap 7.

The gaps 7 provide access to an internal volume, between the plates 5.

The scoop 1 rotates about the axis 3 in response to a flow of fluid toward the turbine in a direction substantially at a right angle to the axis 3. When present in a fluid flow toward the gaps 7, the scoop is configured to experience drag of a magnitude much 10 greater than the drag experienced when present in a fluid flow of the same magnitude, but directed toward the convex side 11.

The outer wall sections 23 prevents the working fluid from being lost through the convex side 11 of the scoop, after entering the scoop through the concave side 9 via gaps 7, and instead directs it through one of the holes 13. The fluid continues to move 15 through the holes 13 in successive plates 5 before exiting the turbine at either one axial end, or the other axial end.

Fluid that is unable to pass between the plates 5, due to an area of restricted volume caused by the boundary layer, is neither stopped nor reflected, but rather is deflected around the helical concave side 9.

20 Figure 6 shows a part of a turbine arrangement according to a second embodiment of the present invention, which is a modification of the first embodiment (shown in figures 1 to 5). The second embodiment differs from the first embodiment in the following ways. A scoop 101 is provided in which each plate 105 is substantially circular. The scoop has a first convex side 109 and a second convex side 111. Second 25 convex side 111 comprises an outer wall. There are no cavities in the outer wall of second convex side 111. The face forming a perimeter of each plate 105, defining the first convex side 109 of the scoop 101 (adjacent the gaps 7) has a rounded profile.

Figure 7 shows a top plan view of one of the plates 105 of the second embodiment (shown in figure 6). Top plate 117 differs from plate 105 in that it does not 30 include a raised curved wall section 23.

As with the scoop 1 of the first embodiment, the scoop 101 of the second embodiment rotates about the axis 3 in response to a flow of fluid toward the turbine in a direction substantially at a right angle to the axis 3. When present in a fluid flow toward

16

the gaps 7, the scoop 101 is configured to experience drag of a magnitude much greater than the drag experienced when present in a fluid flow of the same magnitude, but directed toward the second convex side 111.

The outer wall sections 23 prevents the working fluid from being lost through the 5 second convex side 111 of the scoop 101, after entering the scoop through the first convex side 109 via gaps 7, and instead directs it through one of the holes 13. The fluid continues to move through the holes 13 in successive plates 105 before exiting the turbine at either or both axial ends.

Figure 8 shows a part of a turbine arrangement according to a third embodiment 10 of the present invention, which is another modification of the first embodiment (shown in figures 1 to 5). The third embodiment differs from the first embodiment in the following ways. Three scoops 201 are shown, disposed symmetrically about an axis 3 (shown as a dotted line), and configured to rotate about the axis 3. The scoops 201 are composed of a plurality of substantially flat plates 205, disposed at right angles to the axis 15 and spaced apart from one another such that fluid may pass between the plates through gaps 7. Each scoop 201 has a concave side 209 and a convex side 211. Convex side 211 comprises an outer wall. There are no cavities in the outer wall of convex side 211.

Each plate 205 includes nine circular holes 13 therethrough, disposed symmetrically about the axis. The plates 205 are substantially identical to each other, and 20 shaped in a three-pointed star or three-lobed form. The face forming a perimeter of each plate 205, defining the concave sides 209 (adjacent the gaps 7), is chamfered.

The arrangement shown comprises twenty-three plates, each displaced by more than 5 degrees, such that the top plate is rotationally displaced by 120 degrees relative to the bottom plate.

25 Figure 9 shows a top plan view of one of the plates 205 of the third embodiment

(shown in figure 8). At the centre of plate 205, surrounding the axial bore 15, is a platform 227. The platform 227 includes raised portions 229 that enable correct spacing of the plates 205. The raised portions 229 also allows correct alignment of the plates 205, so that the external profile of the turbine can be selected with a high degree of precision. 30 The platform 227 also includes attachment holes 231 therethrough, configured to accept a bolt, so as to enabling rigid connection of the plates 205 together.

As with the scoop 1 of the first embodiment, and the scoop 101 of the second embodiment, the scoops 201 of the third embodiment rotate about the axis 3 in response

17

to a flow of fluid toward the turbine in a direction substantially at a right angle to the axis 3. When present in a fluid flow toward the gaps 7, each scoop 201 is configured to experience drag of a magnitude much greater than the drag experienced when present in a fluid flow of the same magnitude, but directed toward the scoop's 201 respective convex 5 side 211.

The outer wall sections 23 prevent the working fluid from being lost through the convex sides 211 of the scoops 201, after entering the scoops through the concave sides 209 via gaps 7, and instead directs it through one of the holes 13. The fluid continues to move through the holes 13 in successive plates 205 before exiting the turbine at either or 10 both axial ends.

Figure 10 shows a part of a turbine arrangement according to a fourth embodiment of the present invention, which is a modification of the second embodiment (shown in figures 6 and 7). The fourth embodiment differs from the second embodiment in the following ways. A scoop 301 is provided, in which twenty plates 105 are spaced 15 from each other at varying distances. The spacing shown is determined with a harmonic profile; that is, the spacing between the first plate and the second plate is proportional to arccos(0.9), the spacing between the second plate and the third plate is proportional to arccos(0.8), the spacing between the third plate and the fourth plate is proportional to arccos(0.7), and so on. The gaps 307 between plates 105 vary accordingly. In order to 20 function in the manner described above with respect to the first embodiment, the height of the raised curved wall section 323 of each plate 105 is chosen so as to abut the plate 105 above.

In addition, the fourth embodiment also includes an exhaust pipe coupled to each end of the passage, and angled to provide additional rotational thrust to the turbine. The 25 exhaust pipes are bent to an angle of 90 degrees in order to direct fluid exiting the passage at right angles to the axis.

Figure 11 shows a part of a turbine arrangement according to a fifth embodiment of the present invention, which is a modification of the fourth embodiment (shown in figure 10). The fifth embodiment differs from the fourth embodiment in the following 30 ways. A scoop 401 is provided, in which twenty-one plates 405 are spaced from each other by gaps 407, and connected via a raised curved wall section 423 on each plate 405. The diameter of each plate 405 varies along an axis 3 of the scoop 401, such that plates 405 nearer an axial end of the scoop 401 have a larger diameter than plates 405 nearer the

18

axial middle of the scoop 401. The diameters of each plate 405 in the figure are determined using a harmonic function; that is, the external profile of the scoop in a vertical plane follows a section of a sine curve. Accordingly, a first fluid collecting side 409 is saddle shaped; that is, the first fluid collecting side 409 curves out in a direction 5 substantially parallel to the axis 3 and curves in in a direction substantially about the axis 3. Similarly, a second fluid shedding side 411 is also saddle shaped.

Holes 413 provided in each plate are centrally located such that a passage formed by the holes 413 is aligned along the axis 3. Guide ribs 425 are disposed on the inner edge of each hole 413. A top plate 417 differs from the other plates 405 in that it is 10 substantially thickened and has no wall 423. The upper surface of top plate 417 is curved to allow for improved fluid flow around the scoop. The lower end of the scoop 401 is not shown in detail, but is configured to be mountable on a bearing arrangement.

An optional feature is also shown in figure 11, where three aerofoils 435 are connected to upper and lower portions of the scoop, to assist rotation about the axis 3. 15 The aerofoils 435 are bow shaped; that is, the aerofoils 435 extend further from the axis 3 toward the axial middle of the scoop 401 than at the axial ends of the scoop 401.

Figure 12 shows a cutaway perspective view of the ends of a passageway 521 according to a sixth embodiment of the present invention, similar to passageway 21 of the first embodiment. A cone 537 is provided at a first end of the passage 521, and has a flat 20 circular base, a conic axis passing through the centre of the base at a right angle thereto, and an apex located on the conic axis. The cone 537 is orientated such that the base lies in the plane of a top plate 517, and the apex extends into the passage 521. The cone 537 is connected to the top plate 517 by connecting rods 539.

A volute truncated cone 541 is provided at a second end of the passage 521, and 25 has a curved external wall, an open-ended flat circular base, an open-ended flat circular top, and a truncated conic axis passing through the centre of the open-ended base and the open-ended top. The volute truncated cone 541 is oriented such that the open-ended top lies in the plane of a plate 505. The volute truncated cone 541 is connected to the plate by an extension of the plate to which the volute truncated cone is connected. 30 In this way, a vortex present in the passage 541 can be split into a warm, rarefied stream (indicated by A in the figure) and a cool, dense stream (indicated by B in the figure). Thus, the present invention may provide a heating and/or cooling medium. That

19

is, the exhaust streams may be provided to a location external to the turbine, for instance the inside of a building.

20

Claims

1. A turbine, comprising a scoop configured to rotate about an axis in response to a flow of fluid toward the turbine in a direction substantially at a right angle to the axis, the 5 scoop formed from a plurality of substantially flat plates disposed at right angles to the axis and spaced apart from one another such that fluid may pass between the plates, wherein the plates are configured to provide the scoop with a first side and a second side, the second side being convex.

10

2. The turbine of claim 1, wherein:

the scoop further comprises an outer wall enclosing the convex side of the scoop;

and each plate includes a hole therethrough, the holes being configured to form a passage for fluid flow in a direction substantially parallel to the axis.

15

3. The turbine of claim 1 or claim 2, wherein each plate is rotationally offset about the axis with respect to adjacent plates, such that the first side has a substantially helical form.

20

4. The turbine of any preceding claim, wherein the hole in each plate is rotationally offset about the axis with respect to adjacent holes, such that the passage formed by the holes has a substantially helical form.

5. The turbine of any preceding claim, wherein each plate comprises tubercles 25 disposed along a face forming a perimeter of the plate and defining the concave side of the scoop.

6. The turbine of any preceding claim, further comprising irregularities in the turbine's surface.

30

7. The turbine of any preceding claim, wherein each plate is shaped as one half of the Taijitu symbol.

21

8. The turbine of any one of claims 1 to 6, wherein the turbine comprises at least two scoops, disposed symmetrically about the axis and configured to rotate about the axis together, the scoops formed from the plurality of plates, wherein the plates are configured to provide each scoop with a concave side and a convex side.

5

9. The turbine of any one of claim 2, and claims 3 to 8 when directly or indirectly dependent upon claim 2, wherein each plate is substantially circular.

10. The turbine of any preceding claim, comprising at least two aerofoils disposed 10 symmetrically about the axis and each substantially parallel to the axis, configured to rotate about the axis together in response to a flow of fluid toward the turbine in a direction substantially at a right angle to the axis, wherein each aerofoil is directly or indirectly attached to the scoop, so as to rotate about the axis with the scoop.

15

11. The turbine of any preceding claim, wherein the diameter of the plates varies along the axis of the turbine.

12. The turbine of any preceding claim, wherein the diameter of the holes varies along the axis of the turbine.

20

13. The turbine of any preceding claim, wherein the plates are spaced apart from one another by a distance that varies along the axis of the turbine.

14. The turbine of any one of claim 2, and claims 3 to 13 when directly or indirectly 25 dependent upon claim 2, further comprising guide ribs disposed on an internal perimeter of each hole, for guiding flow of fluid within the passage.

15. The turbine of any one of claim 2, and claims 3 to 14 when directly or indirectly dependent upon claim 2, further comprising:

30 a volute truncated cone disposed at an end of the passage; and a cone disposed at an opposing end of the passage.

22

16. The turbine of any one of claim 2, and claims 3 to 15 when directly or indirectly dependent upon claim 2, further comprising an exhaust pipe coupled to an end of the passage, and angled to provide additional rotational thrust to the turbine.

5

17. A turbine substantially as hereinbefore described with reference to the accompanying figures.