GB2601764A

GB2601764A - Energy extraction system and method of use

Info

Publication number: GB2601764A
Application number: GB2019361.1A
Authority: GB
Inventors: Coulson Neil
Original assignee: Individual
Current assignee: Individual
Priority date: 2020-12-09
Filing date: 2020-12-09
Publication date: 2022-06-15
Also published as: GB202019361D0

Abstract

A vertical axis fluid flow turbine 10 comprises upper and upper rotary disc aerofoils 14, 16 and a plurality of blades 24 connected between the upper and lower discs 14, 16. A port 30 in the upper aerofoil 14 allows equalisation of pressure between the fluid volume 29 between the upper and lower aerofoil discs, and the fluid above the disc. The aerofoils 14, 16 may have a raised dome or cone shape. The turbine may be used with a horizontal (transverse) axis.

Description

1 ENERGY EXTRACTION SYSTEM AND METHOD OF USE 3 The present invention relates to a system and method for the conversion of fluid flow 4 energy into mechanical rotational energy for mechanical work and/or electrical generation, in particular the invention relates to a power generation system and method of use for 6 conversion of kinetic energy from wind or water into electricity or other forms of energy.

8 Background to the invention

Energy extraction from wind and water flows have been used for centuries in mills for 11 various mechanical processes. Later more efficient turbines harnessed the energy from 12 fluid flows to generate electricity.

14 Turbines have a number of vanes or blades which depending on the turbine type rotate about either a horizontal or a vertical axis. Existing turbines technology are governed by 16 Betz's law which limits the efficiency of a turbines due to frictional and resistance losses 17 during the turbine operation.

19 Current commercial turbines have a number of disadvantages, they are expensive, inefficient. The turbines also consume electricity during period of non-production (at flow 21 speeds lower or higher than their production window) and require a large infrastructure in 22 remote locations.

24 Another issue with current turbine technology is that they create considerable drag and turbulence which can create apparatus vibration and noise. Pulsations from turbulent fluid 26 flow around a current turbine can result in bearing damage and fatigue of turbine 27 components.

29 There is need for a power generation system and method of use which addresses one or more of the problems associated with known prior art systems, including those identified 31 above.

1 Summary of the invention

3 It is an object of an aspect of the present invention to obviate or at least mitigate the 4 foregoing disadvantages of turbine technology.

6 It is another object of an aspect of the present invention to provide a robust and efficient 7 system and method of use configured to extract energy from a range of water or wind flow 8 speeds.

It is a further object of an aspect of the present invention to provide a turbine apparatus 11 and method of use which is configured for use in an urban or industrial environment.

13 It is another object of an aspect of the present invention to provide a low profile 14 aerodynamic omni-directional turbine apparatus configured to enable flow through the turbine apparatus.

17 Further aims of the invention will become apparent from the following description.

19 According to a first aspect of the invention, there is provided a system for extracting energy from a fluid flow stream comprising 21 at least one turbine apparatus wherein each turbine apparatus comprises: 22 an upper aerofoil; 23 a lower aerofoil; 24 a plurality of blades interconnecting the upper aerofoil and lower aerofoil; a shaft; and 26 a port in the upper aerofoil configured to equalise pressure in a fluid volume between the 27 upper and lower aerofoil.

29 The plurality of blades (also known as vanes) may be arranged to allow flow through the apparatus between the upper and lower aerofoils. The plurality of blades may be arranged 31 to allow flow through the apparatus between the upper and lower aerofoils in a direction 32 generally transverse to the longitudinal axis of the shaft. The system may be configured to 33 allow fluid flow through the at least one turbine apparatus without changing the direction of 34 flow.

1 If the shaft is a vertical shaft the plurality of blades may be arranged to allow flow generally 2 horizontally through the apparatus between the upper and lower aerofoils.

4 The system may be configured to allow fluid flow entering the apparatus in a horizontal plane to pass through and exit the at least one turbine apparatus in the horizontal plane.

7 If the shaft is a horizontal shaft the plurality of blades may be arranged to allow flow 8 generally vertically through the apparatus between the upper and lower aerofoils.

9 The system may be configured to allow fluid flow entering the apparatus in a vertical plane to pass through and exit the at least one turbine apparatus in the vertical plane.

12 The upper aerofoil may have an outer diameter which may be larger than the outer 13 diameter of the lower aerofoil. The lower aerofoil and/or the upper aerofoil may be 14 connected to the shaft. The at least one apparatus may comprise a base connected to the lower aerofoil. The base may be connected to the shaft. The system may comprise at least 16 one generator connected to the shaft. The at least one generator may be configured to be 17 driven by rotation of the shaft. The system may comprise at least one mechanical device 18 connected to the shaft. The at least one mechanical device may be configured to be driven 19 by rotation of the shaft.

21 The port may be a pressure equalisation port. The port may be configured to equalise 22 pressure by allowing flow out from the fluid volume between the upper and lower aerofoil.

23 The port may be configured to equalise the pressure of through flowing fluids within the at 24 least one apparatus. The port may be configured to equalise pressure by allowing flow into the fluid volume between the upper and lower aerofoil. The port may be located centrally 26 on the upper aerofoil. The port may be located at the apex of the upper aerofoil.

28 The port may be configured to even or equalise the rotational value in turbulent conditions 29 whereby gusts, eddies, foreign bodies, or restrictions may increase or decrease the nominal flow velocity.

32 The port may be configured to equalise pressure in the fluid volume by outward flow or 33 venting fluid from the at least one apparatus through the port. Any gusts, eddies, foreign 34 bodies or restriction to the though flow in the downstream side of the at least one apparatus may cause a high pressure within the fluid volume between the upper and lower 1 aerofoil which may be equalised outward flow or venting fluid from the at least one 2 apparatus through the port.

4 The port may be configured to equalise pressure in the fluid volume by inward flow from outside the at least one apparatus into the at least one apparatus through the port. Any 6 gusts, eddies, foreign bodies, or restriction to the though flow in the upstream side of the at 7 least one apparatus may cause a low pressure within the at least one apparatus which 8 may be equalised by inward flow through the port.

The plurality of blades may have an axis of rotation substantially perpendicular to a flow 11 direction of a fluid flow stream. The plurality of vanes may be mounted between the upper 12 and lower aerofoils. The plurality of vanes may be mounted on an inner or upper surface of 13 the lower aerofoil and to an inner or lower surface of the upper aerofoil.

The plurality of blades, lower aerofoil, upper aerofoil and/or the shaft may be coaxial. The 16 plurality of blades, lower aerofoil, upper aerofoil and/or the shaft may be rotationally 17 coupled. The plurality of blades may be configured to interact with the fluid drawn though 18 the apparatus to create a rotational movement of the turbine apparatus. The plurality of 19 blades may be configured to rotate the apparatus about a vertical axis. The turbine apparatus may be a vertical axis turbine apparatus. The plurality of blades may be 21 configured to rotate the apparatus about a horizontal axis. The turbine apparatus may be a 22 horizontal axis turbine apparatus.

24 The at least one turbine apparatus may comprise a flow cavity. The flow cavity may be a central flow cavity between the lower aerofoil and upper aerofoil. The flow cavity is an 26 unobstructed space in the at least one apparatus.

28 The plurality of the blades may extend from the periphery of the lower aerofoil and upper 29 aerofoil to the flow cavity. Preferably the flow cavity is located beneath or adjacent to the port. The flow cavity may be located at the apex of the lower aerofoil. The apparatus may 31 be configured to pass fluid from the inlet through the flow cavity to the outlet.

33 The plurality of the blades may have any number of blades. The number of blades may be 34 odd or even. The number of blades should not impede the through fluid flow.

1 The at least one apparatus may be configured to be positioned in or disposed adjacent to 2 a flow stream or portion of a flow stream. The at least one apparatus may be configured to 3 draw fluid through the at least one apparatus between the aerofoils. The at least one 4 apparatus may be configured such that a portion of the drawn fluid is forced against a one or more of the plurality of the blades to creating rotational movement. The at least one 6 apparatus may be configured to produce rotational energy with minimal disruption to the 7 natural drawn fluid flow 9 The inlet and outlet of the turbine apparatus may be configured to be located generally transverse to longitudinal axis of the shaft. The inlet and outlet of the turbine apparatus 11 may be located between the upper aerofoil and lower aerofoil. The inlet of the turbine 12 apparatus may be configured to be an inlet in a first fluid flow direction and an outlet in a 13 second fluid flow direction. The outlet of the turbine apparatus may be configured to be an 14 outlet in a first fluid flow direction and an inlet in a second fluid flow direction.

16 The profile or shape of the upper aerofoil and/or lower aerofoil may be changed based on 17 the fluid flow velocity.

19 The upper aerofoil may have a shape configured to direct fluid flow over the external surface of the upper aerofoil. The upper aerofoil may have a shape configured to direct 21 fluid flow over the external surface of the upper aerofoil towards and then away from the 22 port.

24 The upper aerofoil member may have a shape configured to direct the fluid flow over the external surface of the upper aerofoil towards and/or over the port.

27 The lower aerofoil may have a shape or profile configured to direct fluid flow along an inner 28 surface of the lower aerofoil from the inlet to the outlet.

The upper aerofoil and/or the lower aerofoil may be configured to direct flow entering the 31 turbine apparatus from a first direction to a second direction exiting the apparatus where 32 the first and second directions are substantially parallel. Preferably there is minimal 33 angular displacement between the first direction and second directions. Preferably there is 34 minimal angular displacement of flow as it passes through the apparatus.

1 The upper aerofoil and/or the lower aerofoil may be configured such that the flow exiting 2 the turbine apparatus is substantially parallel with the flow stream.

4 The lower aerofoil, upper aerofoil and/or the plurality of blades may have a shape configured to direct the flow from a first flow path in the horizontal plane to a second flow 6 path in the horizontal plane. The first and second flow paths may be substantially parallel.

7 The first and second flow paths may be non-parallel.

9 The lower aerofoil, upper aerofoil and/or the plurality of blades may have a shape configured to direct the flow from a first flow path in the vertical plane to a second flow path 11 in the vertical plane. The first and second flow paths may be substantially parallel. The first 12 and second flow paths may be non-parallel 14 The upper aerofoil and/or the lower aerofoil may have the same shape or profile. The upper aerofoil and/or the lower aerofoil may be parallel or substantially parallel. The upper 16 aerofoil and/or the lower aerofoil may have the different shapes or profiles to one another.

17 The upper aerofoil and/or the lower aerofoil may be non-parallel.

19 The upper aerofoil may be selected from a variety of shapes including a convex sheet, a cone, dome, truncated cone, pyramid, a ring, a slanted or sloped ring or a raised disc.

22 The lower aerofoil may be selected from a variety of shapes including a convex sheet, a 23 cone, dome, truncated cone, pyramid, or a raised disc.

The upper aerofoil and/or lower aerofoil may be set or sloped at an angle to the horizontal 26 plane. The angle may range from 5 degrees to 40 degrees to the horizontal plane. The 27 angle may range from 20 degrees to 30 degrees to the horizontal plane.

29 The upper aerofoil and/or lower aerofoil may be set or sloped at an angle to the longitudinal axis of the shaft. The angle to the longitudinal axis of the shaft may range from 31 50 degrees to 85 degrees. The angle to the longitudinal axis of the shaft may range from 32 60 degrees to 70 degrees.

34 The at least one apparatus may be configured to operates in all forms of laminar and/or non-laminar flows. The at least one apparatus may be configured to operate in a fluid flow 1 stream having a minimum fluid flow speed of approximately 1m/s. The at least one 2 apparatus may be configured to operate in a fluid flow stream having a minimum fluid flow 3 speed of less than 1m/s. The at least one apparatus may be configured to operate in fluid 4 flow speeds from less than 1m/s and upwards. The at least one apparatus may be configured to operates in all forms of laminar and/or non-laminar flow natural fluid flow of 6 speeds from less than 1m/s and upwards.

8 The at least one apparatus may have a body formed from the upper aerofoil and lower 9 aerofoil. The at least one apparatus may have a body formed from the upper aerofoil and lower aerofoil and the interconnected plurality of blades between the upper aerofoil and 11 lower aerofoil. The at least one apparatus may have a body formed from an outer surface 12 or the upper aerofoil and an outer surface of the lower aerofoil.

14 The upper aerofoil, lower aerofoil and plurality of blade may be an integral unit. The at least one apparatus may be an open environment turbine. The at least one apparatus may 16 have a mono block construction. The upper aerofoil, lower aerofoil and plurality of blades 17 may constitute a single mono-block component. The mono-block component may be used 18 to produce rotational movement from fluid flow.

The apparatus may be configured to allow inlet flow around the periphery of the upper 21 aerofoil and lower aerofoil. The apparatus may be configured to allow outlet flow around 22 the periphery of the upper aerofoil and lower aerofoil. The apparatus may be 23 omnidirectional.

The fluid may be water, air, or gas. The apparatus may be located on land, subsea, or on 26 the surface of water. The apparatus may be used in residential or industrial applications.

28 The system may comprise two or more apparatus. The two or more apparatus may have a 29 stacked arrangement. The two or more apparatus may be arranged mounted on the same shaft. The shafts of the two or more apparatus may be coaxially arranged such that the 31 two or more apparatus are rotationally coupled. At least one of the two or more apparatus 32 may be inverted. By inverting at least one of the two or more apparatus as one apparatus 33 is rotated in a first direction the inverted apparatus is rotated in an opposing direction.

1 The apparatus may be configured to have a low profile. The apparatus may be configured 2 to have an aerodynamic or hydrodynamic profile design. The profile design may be 3 configured to enable fluid flow through the turbine apparatus with a minimal or limited 4 angular displacement.

6 The at least one apparatus may be configured to mounted transverse to the direction of 7 the flow stream. The apparatus may be configured to draw fluid flow from a flow stream.

9 The at least one apparatus may be configured to operate in an open environment. The apparatus may be configured to operate without a shroud, diverter, external housing, or 11 duct.

13 The at least one apparatus may be configured to rotate in either clockwise or anti- 14 clockwise direction. The at least one apparatus may be configured to rotate in either clockwise or anti-clockwise direction depending on flow stream criteria or location.

16 The at least one apparatus may be configured to be mountable to a structure.

17 The shaft may be configured to be attachable or mountable to a structure. The shaft may 18 be configured to be attached or mounted to a structure at one or both ends of the shaft.

According to a second aspect of the invention, there is provided an apparatus for 21 extracting energy from a fluid flow stream comprising: 22 an upper aerofoil; 23 a lower aerofoil; 24 a plurality of blades interconnecting the upper aerofoil and lower aerofoil; a shaft; and 26 a port in the upper aerofoil configured to equalise pressure in a fluid volume between the 27 upper and lower aerofoil.

29 Embodiments of the second aspect of the invention may include one or more features of the first aspect of the invention or its embodiments, or vice versa.

32 According to a third aspect of the invention, there is provided a system for extracting 33 energy from a fluid flow stream comprising: 34 at least one turbine apparatus wherein each turbine apparatus comprises: an upper aerofoil; 1 a lower aerofoil; 2 a plurality of blades with an axis of rotation arrangement substantially perpendicular to a 3 flow direction of the flow stream; 4 a shaft; a port in the upper aerofoil configured to equalise pressure in a fluid volume between the 6 upper and lower aerofoil; and 7 a flow cavity; 8 wherein the upper aerofoil, lower aerofoil and/or the plurality of blades are configured to 9 direct the fluid flow to and from the flow cavity through the at least one turbine apparatus.

11 The port may be located above the flow cavity.

13 Embodiments of the third aspect of the invention may include one or more features of the 14 first or second aspects of the invention or their embodiments, or vice versa.

16 According to a fourth aspect of the invention, there is provided a system for extracting 17 energy from a fluid flow stream comprising 18 two or more turbine apparatus wherein each turbine apparatus comprises: 19 an upper aerofoil; a lower aerofoil; 21 a plurality of blades with an axis of rotation arrangement substantially perpendicular to a 22 flow direction of the flow stream; 23 a shaft; 24 a port in the upper aerofoil configured to equalise pressure in a fluid volume between the upper and lower aerofoil.

27 The lower aerofoil and/or the upper aerofoil may be connected to the shaft. The at least 28 one apparatus may comprise a base connected to the lower aerofoil. The base may be 29 connected to the shaft. The system may comprise at least one generator connected to the shaft. The at least one generator may be configured to be driven by rotation of the shaft.

31 The system may comprise at least mechanical device connected to the shaft. The at least 32 one mechanical device may be configured to be driven by rotation of the shaft.

1 Each of the turbine apparatus may comprise a flow cavity. The upper aerofoil, lower 2 aerofoil and/or the plurality of blades are configured to direct the fluid flow to and from the 3 flow cavity through the at least one turbine apparatus.

Embodiments of the fourth aspect of the invention may include one or more features of 6 any of the first to third aspects of the invention or their embodiments, or vice versa.

8 According to a fifth aspect of the invention, there is provided an apparatus for extracting 9 energy from a fluid flow stream comprising an upper aerofoil; 11 a lower aerofoil; 12 a plurality of blades interconnecting the upper aerofoil and lower aerofoil; 13 a shaft; and 14 a port in the upper aerofoil configured to equalise pressure in a fluid volume between the upper and lower aerofoil; 16 wherein the upper aerofoil, lower aerofoil and plurality of blades are configured to direct 17 fluid flow through the apparatus in a direction transverse to the longitudinal axis of the 18 shaft.

Embodiments of the fifth aspect of the invention may include one or more features of any 21 of the first to fourth aspects of the invention or their embodiments, or vice versa.

23 According to a sixth aspect of the invention, there is provided a method of extracting 24 energy from a fluid flow stream using the apparatus of the first, second, third, fourth or fifth aspects of the invention.

27 Embodiments of the sixth aspect of the invention may include one or more features of any 28 of the first to fifth aspects of the invention or their embodiments, or vice versa.

According to a seventh aspect of the invention, there is provided a method of extracting 31 energy from a fluid flow stream, the method comprising: 32 providing a system for extracting energy from a fluid flow stream comprising 33 at least one turbine apparatus wherein each turbine apparatus comprises: 34 an upper aerofoil; a lower aerofoil; 1 a plurality of blades interconnecting the upper aerofoil and lower aerofoil; 2 a shaft; and 3 a port in the upper aerofoil configured to equalise pressure in a fluid volume between the 4 upper and lower aerofoil; and disposing the at least one turbine apparatus in a fluid flow stream.

7 The method may comprise directing fluid flow through the apparatus.

9 The method may comprise contacting the flow of fluid exiting the fluid outlet with an unobstructed flow stream. The method may comprise directing a portion of flow over the 11 apparatus. The method may comprise mounting the at least one turbine apparatus in or on 12 a structure.

14 Embodiments of the seventh aspect of the invention may include one or more features of any of the first to sixth aspects of the invention or their embodiments, or vice versa.

17 According to an eighth aspect of the invention, there is provided a method of extracting 18 energy from a fluid flow stream, the method comprising: 19 providing a system for extracting energy from a fluid flow stream comprising at least one turbine apparatus wherein each turbine apparatus comprises: 21 an upper aerofoil; 22 a lower aerofoil; 23 a plurality of blades interconnecting the upper aerofoil and lower aerofoil; 24 a shaft; and a port in the upper aerofoil configured to equalise pressure in a fluid volume between the 26 upper and lower aerofoil; 27 connecting the at least one apparatus to an electrical generator; and 28 disposing the at least one turbine apparatus in a fluid flow stream.

Preferably the shaft rotational coupled to the plurality of blades, upper aerofoil and/or lower 31 aerofoil. The electrical generator may be connected to the shaft.

33 Embodiments of the eighth aspect of the invention may include one or more features of 34 any of the first to seventh aspects of the invention or their embodiments, or vice versa.

1 According to a ninth aspect of the invention, there is provided a method of extracting 2 energy from a fluid flow stream, the method comprising: 3 providing a system for extracting energy from a fluid flow stream comprising 4 at least one turbine apparatus wherein each turbine apparatus comprises: an upper aerofoil; 6 a lower aerofoil; 7 a plurality of blades interconnecting the upper aerofoil and lower aerofoil; 8 a shaft; and 9 a port in the upper aerofoil configured to equalise pressure in a fluid volume between the upper and lower aerofoil; 11 connecting the at least one apparatus to a rotary device; and 12 disposing the at least one turbine apparatus in a fluid flow stream.

14 Preferably the shaft rotational coupled to the plurality of blades, upper aerofoil and/or lower aerofoil. The rotary device may be connected to the shaft to transmit rotary motion of the 16 apparatus to actuate or drive a rotary motion device.

18 Embodiments of the ninth aspect of the invention may include one or more features of any 19 of the first to eighth aspects of the invention or their embodiments, or vice versa.

21 According to a tenth aspect of the invention, there is provided a method of extracting 22 energy from a fluid flow stream using the system of any of the first to fifth aspects of the 23 invention.

Embodiments of the tenth aspect of the invention may include one or more features of any 26 of the first to ninth aspects of the invention or their embodiments, or vice versa.

28 Brief description of the drawings

There will now be described, by way of example only, various embodiments of the 31 invention with reference to the drawings, of which: 33 Figure 1A shows a perspective view of an energy generation apparatus according to an 34 embodiment of the invention with the upper aerofoil transparent for clarity; 1 Figure 1B shows an exploded view of the energy generation apparatus of Figure 1A; 3 Figure 2 shows a sectional side view of the energy generation apparatus of Figures 1A 4 showing nominal flow through and around the apparatus; 6 Figure 3A to 30 show sectional side views of an energy generation apparatus of Figure 1A 7 showing fluid flow paths through the apparatus with the blades omitted for clarity; 9 Figure 4A and 4B show plan views of energy generation apparatus of Figure 1A at a first rotation position with the upper aerofoil omitted for clarity; 12 Figure 5A and 5B show plan views of energy generation apparatus of Figure 1A at a 13 second rotation position with the upper aerofoil omitted for clarity; Figure 6A and 6B are schematic fluid flow diagrams of constant fluid density for a prior art 16 turbine and the apparatus of Figure 1A respectively; 18 Figure 7 is a perspective view of an energy generation system with two generators 19 connected to the central shaft according to an embodiment of the invention; 21 Figure 8 is a perspective view of an energy generation system with two turbine apparatus 22 in a stacked configuration according to an embodiment of the invention; 24 Figure 9 is a perspective view of an energy generation system comprising two turbine apparatus in a stacked configuration with one turbine inverted according to an embodiment 26 of the invention; 28 Figure 10 is a perspective view of an energy generation system mounted on a structure 29 according to an embodiment of the invention;

31 Detailed description of preferred embodiments

33 Figures 1A and 1B show schematic perspective assembled and exploded views of a 34 turbine apparatus 10.

1 The turbine apparatus 10 has a body 12 formed from an upper aerofoil 14 and a lower 2 aerofoil 16. In this example, the lower aerofoil 16 is mounted on a central shaft 15. Figures 3 1A and 1B show an optional flat base plate 26 on which the lower aerofoil is mounted. The 4 shaft 15 is connected to a generator 32 to generate electrical energy.

6 In this example the upper aerofoil 14 has a generally truncated cone-shape with a port or 7 aperture 30 located at the apex of the upper aerofoil. The lower aerofoil 16 has a general 8 cone-shape. However, it will be appreciated that the upper and lower aerofoils may have 9 other shapes including convex sheet, dome, pyramid, ring, or a raised disc.

11 The apparatus comprises a blade assembly 22 having a plurality of blades 24. In this 12 example, the blade assembly 22 has five blades mounted and fixed between the upper 13 aerofoil 14 and the lower aerofoil 16. It will be appreciated that this is just one example and 14 that the apparatus may have less than five or more than five blades.

16 Each blade has an upper edge 27a, a bottom edge 27b, an inner edge 27c and an outer 17 edge 27d. The bottom edge 27b of blades are mounted on an inner surface 16a of the 18 lower aerofoil 16. The blades are arranged equidistance from one another around the 19 circumference of lower aerofoil, in this example 72 degrees from one another. The upper edge 27a of blades are mounted on an inner surface 14a of the upper aerofoil 14.

21 The arrangement of the upper and lower aerofoils interconnected by a plurality of blades 22 provide substantial strength and rigidity to the structure of the apparatus 10.

24 The bottom edge 27b of the blades are shorter than the slope or slant length of the lower aerofoil which creates an internal flow cavity 29 between the inner edge 27c of the blades 26 in the apparatus beneath the port 30.

28 This arrangement also defines channels 23 which pass between the periphery of the 29 apparatus and the cavity 29. The channels 23 defined by the volume between the upper aerofoil 14, lower aerofoil 16 and between each of the adjacent blades. The channels 23 31 acts as fluid inlets for fluid entering into the apparatus 10 and as fluid outlets for fluid 32 exiting the apparatus 10.

34 In this example the generally conical shape of the upper and lower aerofoils deflects fluid entering the channels 23 along the inner surfaces of the upper and lower aerofoils and 1 along the blades 24. Flow entering the apparatus is directed along the upward orientated 2 section of the upper and lower aerofoils in the general direction of the apex of the upper 3 and lower aerofoils until it reaches the cavity 29.

Once the flow passes through the cavity the conical shape of the upper and lower aerofoils 6 deflects fluid leaving the internal flow cavity 29 through channels 23 along the downward 7 orientated section of the inner surfaces of the upper and lower aerofoils. Flow is directed 8 in the general direction away from the apex of the upper and lower aerofoils and out of the 9 apparatus.

11 By providing an internal flow cavity 29 flow passes through the apparatus in a direction 12 generally direction transverse to the longitudinal axis of the shaft. In this example as the 13 apparatus is configured to be mounted in the horizontal plane with a vertical axis shaft the 14 flow passes through the apparatus is a generally horizontal direction with minimal resistance. Arranging the turbine transverse to the flow enables the turbine to operate in 16 non-laminar turbulent omni-directional flow streams.

18 By providing flow channels around the periphery of the apparatus enables the apparatus to 19 be omnidirectional and to generate energy from fluid flow from any flow direction without requiring directional adjustment of the apparatus.

22 The energy generation apparatus is designed to be placed on land or subsea such that its 23 rotational axis shown as "A" in Figure 1A is substantially in a perpendicular direction to the 24 flow direction of the fluid flow stream indicated by the arrow "B" in Figure 1A.

26 The blades and interconnected upper and lower aerofoils are configured to rotate around 27 the longitudinal axis of the shaft shown as arrow "A" in Figure 1A.

29 The upper and lower aerofoils are coaxially arranged and in this example are connected to the shaft via the lower aerofoil such that the upper and lower aerofoils are rotationally 31 coupled.

33 In the above example the shaft is connected to a generator generate electrical energy. It 34 will be appreciated that the shaft may be additional or alternatively connected or to a mechanism to use the rotary energy of the shaft.

1 The apparatus 10 has been designed to reduce lift and drag forces from fluid flow passing 2 around and through the apparatus.

4 Lift and drag are the two main resulting factors of a solid body in a fluid flow. Lift is generated by differential pressure and fluid speed over and below an object. Drag is the 6 build-up of turbulent fluid flow whereby the multi-directional chaotic flow reduces the 7 laminar flow velocity, typically caused by flow separation. Drag is generated by the 8 difference in velocity between any solid object and the flow of fluid. All objects will produce 9 both lift and drag in a fluid flow.

11 Flow separation occurs on the upstream, the downstream side and sharp edges of an 12 object in a fluid flow. It occurs on the upstream side due to the physical body of an object 13 preventing continuous flow. The flow trajectory which forces the flow past the edge of an 14 object causes flow separation. Flow separation on the downstream side depends on the velocity, viscosity, and angle of the downstream profile.

17 The apparatus 10 a generally conically shape with aerofoils having an upward orientated 18 section and a downward orientated section. The combination of upward orientated section 19 and a downward orientated section provides even flow streams that follow the contours of the aerofoils.

22 Figure 2 shows representative flow stream over the apparatus 10. As shown in Figure 2 23 the lower aerofoil 16 and upper aerofoil 14 are shaped to reduce the frontal surface area of 24 the apparatus that first contacts a fluid flow stream and thereby reduce the flow separation where nominal flow separates into two or more flow streams. It also reduces or mitigates 26 unwanted outward trajectories and unwanted severity of the downstream turbulence.

28 Figure 2 shows five flow streams show as "A" to "E" passing over or thorough the 29 apparatus 10. The pressure differential between each flow stream remains constant throughout the flow pattern.

32 Flow stream "A" is the fastest flow with the lowest pressure, with flow stream "E" being the 33 slowest flow with the highest pressure.

1 As flow stream "C" contact the apparatus it encounters an impingement zone 40 at the 2 outer edge of the apparatus. The impingement zone 40 is the area of impact of the flow 3 stream at point of flow separation. At impingement zone 40 flow stream "C" separates into 4 two branch flow streams "Cl" and "C2". These diverging branch flow streams flow on either side of the upper aerofoil 14 with flow stream "Cl" flowing over the upper aerofoil 14 6 and flow stream "C2" flowing below the upper aerofoil 14.

8 As the pressure differential between flow streams "C" and "D" remains constant, the 9 pressure differential between "C" and "Cl" is halved reducing lift inside the turbine apparatus 10 and enabling a steady flow through the apparatus 10.

12 To minimise drag the angles of the upper and/or lower aerofoil must be calculated to suit 13 the environment of flow. By minimising the difference between laminar flow trajectory and 14 the flow position of the separation point, which is the point wherein the laminar flow over an object pulls away from the apparatus profile on the downstream side, drag may be 16 reduced.

18 The angle of the upper aerofoil and lower aerofoil are designed to suit the nominal fluid 19 velocity. The lower the fluid velocity the greater the angle of the aerofoils relative to the horizontal plane. In this example, the angle of the upper aerofoil and lower aerofoil is 30° 21 relative to the horizontal plane. However, it will be appreciated that the angle of the 22 aerofoils relative to the horizontal plane may be between 5 degrees and 40 degrees. As 23 the nominal fluid velocity increases the upper aerofoil and lower aerofoil angle should 24 decrease to maintain the aerodynamics.

26 Providing upper aerofoil and lower aerofoils at 30 degree angle to the horizontal plane will 27 be suitable for all conditions. However, there may be some circumstances where the 28 conditions are relatively constant, such as river flow for example, where the only variation 29 would be flood conditions. In these situations, the apparatus can be designed to produce the most optimum output.

32 In the above example the upper aerofoil and lower aerofoils are shown as being parallel to 33 each other with the same angle relative to the horizontal plane. However, it will be 34 appreciated the that upper aerofoil and lower aerofoils are not required to the be parallel and may have different angles to each other within the angle range between 5 degrees 1 and 40 degrees to the horizontal plane. This configuration minimises lift within the turbine, 2 overall drag and a venturi effect that would normally draw the fluid flow in an upward 3 direction creating turbulence in the flow.

It is important that when selecting the angle of the lower aerofoil and the angle of the 6 upper aerofoil that the summit or apex of the lower aerofoil and/or upper aerofoil do not 7 impede the fluid flow though the apparatus.

9 The apparatus 10 has an aerodynamic or hydrodynamic low profile design and is configured to enable fluid flow through the turbine apparatus with a minimal or limited 11 angular displacement. As shown in Figure 2 the flow streams upstream and downstream 12 of the apparatus are minimally displaced. This arrangement of the apparatus provides 13 minimal drag and minimal turbulence downstream of the apparatus.

The inventors have found that acute flow trajectories of large surface areas create large 16 volumes of turbulent flow, in turn causing the incoming streamlines to slow reducing the 17 flow to the turbine. By providing a small frontal area and small impingement zone size 18 reduces the severity of the flow separation and reduces or eliminates unwanted outward 19 trajectories and unwanted downstream turbulence.

21 The aerodynamics or hydrodynamics of the apparatus promote through flow by enabling 22 the pressure equalising port to equalise the internal pressure and permit flow through the 23 turbine body allowing excess fluid to flow above the upper aerofoil and any deficiency of 24 fluid to flow below the upper aerofoil through the pressure equalising port on the downstream side.

27 The aerodynamics or hydrodynamics and flow through arrangement of the apparatus 28 improves the performance by reducing drag and downstream turbulence. This reduces the 29 minimum fluid flow speed required to start rotation of the turbine apparatus. The apparatus is configured to have a start-up speeds of lm/s (2.2mph) and above.

32 Figures 3A to 3C shows representative flow streams through the apparatus 10. The blades 33 have been removed for clarity.

1 Figure 3A shows fluid flow through the apparatus 10 under nominal fluid flow conditions.

2 The fluid flow stream shown as dotted arrow "A" in Figure 3A passing through the channel 3 23 between the upper aerofoil 14 and lower aerofoil 16. The conical shape of the upper 4 aerofoil 14 and lower aerofoil 16 guides the flow stream to rise along the upward orientated section denoted as "U" which is upstream of the centre line "C" of the apparatus 6 in Figure 3A and fall along the downward orientated section denoted as "D which is 7 downstream of the centre line "C" of the apparatus in Figure 3A.

9 Figure 3B shows fluid flow through the apparatus 10 with high pressure fluid flow conditions. The high pressure flow shown as dotted arrow "G" in Figure 3B creates an area 11 of internal high pressure in the apparatus. The port 30 in the upper aerofoil 14 acts as a 12 pressure equalising port. Fluid passes from below the upper aerofoil through the port 30 to 13 outside the apparatus as shown as dotted arrow "E" in Figure 3B. By venting fluid from the 14 apparatus through port 30 the internal pressure of the apparatus is reduced and is equalised, permitting flow through the apparatus along flow path "G1" in Figure 3B.

17 Figure 30 shows fluid flow through the apparatus 10 with low pressure fluid flow 18 conditions. The low pressure flow shown as dotted arrow "H" in Figure 3C creates an area 19 of internal low pressure in the apparatus. The port 30 in the upper aerofoil 14 acts as a pressure equalising port. Fluid passes from above the upper aerofoil 14 through the port 21 30 into the apparatus shown as arrow "J" and along the downstream side of the apparatus 22 with flow stream "H" leaving the apparatus as combined flow streams "H & J" in Figure 3C.

23 By drawing fluid from through port 30 the internal pressure is increased and equalised.

24 This permits flow through the apparatus along flow path "H+J" in Figure 3C.

26 The apparatus 10 is designed to promote horizontal flow through the apparatus by 27 enabling the pressure equalising port to equalise the internal pressure and permit flow 28 through the apparatus allowing excess fluid in high pressure condition to flow out through 29 the port into a flow stream passing above the upper aerofoil. The port also enables and any deficiency of fluid in low pressure flow conditions to enter the apparatus through the 31 port to flow below the upper aerofoil to promote flow through the apparatus along the 32 downstream side. The flow in this manner provides a constant fluid flow through the 33 apparatus.

1 In the above examples the size of the port is the same. However, the inventors have found 2 that the size of the port controls the rotational speed of the turbine. A small port size 3 reduces the revolutions per minute (RPM) of the turbine apparatus rotation. A large port 4 size increases the revolutions per minute (RPM) of the turbine apparatus rotation at the same fluid flow speed.

7 It will be appreciated that the apparatus may be designed based on the location and fluid 8 flow condition of where the apparatus is to be positioned. The port size may be selected 9 based on the location and fluid flow condition of where the apparatus is to be positioned. It will be also be appreciated at the apparatus may comprise an adjustable port size to 11 control the rotational speed of the turbine.

13 Figures 4A to 5B show plan views of the apparatus 10 showing example fluid flow paths 14 through apparatus at different rotation positions of the apparatus. The upper aerofoil has been removed in Figures 4A to 5B for clarity.

17 Figures 4A to 5B show the blade assembly 22 and arrangement of blades 24 in more 18 detail. The blade assembly has five blades 24a, 24b, 24c, 24d and 24e arranged 19 equidistance from one another around the circumference of lower aerofoil, 72 degrees from one other. The blades curve rearwards in the general direction of rotation and 21 provide a drive side 25a and a return side 25b. The generally concave surface of the drive 22 side acts like a scoop to maximise contact of fluid flow. The generally convex surface of 23 the return side 25b reduces drag and negative force on the trailing blades moving against 24 the flow of fluid.

26 Figures 4A and 4B shows the apparatus in use at a first rotation position. In this first 27 position blade 24a is located centrally within a fluid flow path "A" which enters flow 28 channels 23a and 23b. Flow streams "Al" entering channel 23a and flow stream "A2" 29 entering channel 23b pass around blade 24a and through the apparatus and exits the apparatus between blades 24c and 24d in channel 23d.

32 Flow stream "A3" contacts the return side 25b of blade 24b and is diverted along the 33 surface of the return side 25b of blade 24b altering the flow stream flow path. As the 34 diverted flow stream A3 passes through the apparatus it contacts flow streams "Al" and "A2" and exits the apparatus between blades 24c and 24d in channel 23d in a parallel flow 36 path to flow stream "Al" and "A2". The generally convex surface of the return side 25b of 1 blade 24b reduces drag and assists movement of the return side 25b of blade 24b in a 2 clockwise direction transverse to the fluid flow direction.

4 This forces the majority of the fluid flow that is not used to power the turbine such as flow streams Al", "A2" and "A3" which is considered non-productive fluid to flow through the 6 blade arrangement and the apparatus. The fluid through arrangement of the blade 7 assembly 22 minimises internal restrictions and friction between non-productive fluid and 8 the trailing blade 24b and therefore minimises the negative force on the trailing blade 24b.

Flow stream "A4" contacts the drive side 25a of blade 24e and exerts a force on blade 24e 11 rotating the blade assembly 22 and the connected upper and lower aerofoils in a clockwise 12 direction shown by arrow "D" in Figure 4B.

14 As the lower aerofoil is fixed on the shaft 15 the fluid flow stream acting on the blades 24 also rotates the shaft in a clockwise direction. The shaft may be connected to a generator 16 to generate electrical energy or to a mechanism to use the rotary energy of the shaft.

18 Figures 5A and 5B shows the apparatus in use at a second rotation position. In this 19 second position blades 24a and 24b are located are the peripheral edge of a fluid flow path "B" which enters flow channels 23a, 23b and 23c. Flow streams "B1" and "B2" enter 21 channel 23b and pass between blades 24a and 24b and through the apparatus and exits 22 the apparatus around blade 24d. Flow stream "B1" exits the apparatus through channel 23 23e between blades 24d and 24e. Flow stream "B2" exits the apparatus through channel 24 23d between blades 24c and 24d.

26 Flow stream "B3" contacts the return side 25b of blade 24c and is diverted along the 27 surface of the return side 25b of blade 24c altering its flow path. As the diverted flow 28 stream B3 passes through the apparatus it contacts flow streams "B1" and exits the exits 29 the apparatus through channel 23e between blades 24d and 24e in a parallel flow path to flow stream "B1". The generally convex surface of the return side 25b of blade 24c 31 reduces drag and assists movement of the return side 25b of blade 24c in a clockwise 32 direction transverse to the fluid flow direction.

1 Flow stream "B4" contacts the drive side 25a of blade 24e and exerts a force on blade 24e 2 rotating the blade assembly 22 and the connected upper and lower aerofoils in a clockwise 3 direction shown by arrow "D" in Figure 5B.

Figure 6A and 6B show schematic representations of fluid flow for a constant fluid density 6 comparison between a typical vertical axis wind turbine shown in Figure 6A and the 7 apparatus 10 shown in Figure 6B.

9 Figure 6A shows a prior art vertical axis wind turbine 300 in a fluid flow area 355 with an upstream flow area is denoted "U F' and a downstream flow area denoted as "DF".

11 Constant fluid density studies show a large area of low velocity turbulent flow (shaded) 12 denoted as "TF" in Figure 6A in the downstream flow area.

14 The large area of low velocity turbulent flow shown in Figure 6A is due to drag generated by the difference in velocity between the turbine 300 and the flow of fluid in the fluid flow 16 area 355. The turbine 300 has trapped internal turbulence within the turbine which 17 prevents through flow in the turbine. The height of the turbine 300 and the column of drag 18 downstream of the turbine create turbulence.

Figure 6B shows apparatus 10 in a fluid flow area 55 with an upstream flow area is 21 denoted "UP' and the downstream flow area is denoted "DF". Constant fluid density 22 studies show that the low profile apparatus 10 is capable of providing a constant fluid flow 23 through the apparatus 10 and therefore the area of low velocity turbulent flow (shaded) 24 denoted as "TF" in Figure 6B in the downstream flow area is significantly reduced when

compared to the prior art turbine 300.

27 The apparatus 10 has a low profile design and is configured to enable fluid flow through 28 the turbine apparatus with a limited angular displacement. This arrangement provides a 29 reduced drag factor with minimal turbulent wake column height and a minimal overall length of the turbulence wake.

32 In the examples above the cross-sectional area of the downstream flow area shown as 33 "DF" in Figures 6A and 6B is shown at the same fluid speed in Figures 6A and 6B. It will 34 be appreciated that the cross-sectional area may vary with different fluid speeds.

1 The low profile aerodynamic drawn of apparatus 10 and the arrangement of aerofoils, 2 blades and pressure equalising port results in a reduction in the area of downstream low 3 velocity flow which provide more effective use of fluid flow and reduces impact on multiple 4 turbines in close proximity.

6 Figure 7 shows an apparatus 100. The apparatus is similar to the apparatus 10 described 7 in Figures 1A and 1B and will be understood from the description of Figures 1A and 1B.

8 However, the apparatus 100 is connected to two generators 132a and 132b connected to 9 the shaft 115 to generate electrical energy. In this example a first generator 132a is connected to a first end of the shaft 115 above the upper aerofoil 114 and a second 11 generator 132b is connected to a second end of the shaft 115 below the lower aerofoil 12 116.

14 Figures 8 and 9 show different arrangements of the stacking multiple turbine apparatus to maximise the energy extracted from the flow.

17 Figure 8 shows a system 200 having two apparatus 220 arranged in a stacked 18 configuration mounted on the same shaft 215. There is a gap 260 between the upper 19 apparatus 220a and the lower apparatus 220b to allow fluid flow through the port 230b in the lower apparatus 220b to equalise internal pressure in the lower apparatus 220b.

22 Each of the apparatus 220 is similar to the apparatus 10 described in Figures 1A and 1B 23 and will be understood from the description of Figures 1A and 1B.

The system 200 has two generators 232a and 232b connected to the shaft 215 to 26 generate electrical energy. A first generator 232a is connected to a first end of the shaft 27 215 above the upper aerofoil 214a of the upper apparatus 220a and a second generator 28 232b is connected to a second end of the shaft 215 below the lower aerofoil 216b of lower 29 apparatus 220b.

31 In this example two turbine apparatus are shown stacked on the same shaft. However, it 32 will be appreciated that the apparatus 220 may be considered as modular components of 33 the system 200 and the system may comprise any number of turbine apparatus 220 34 stacked on the central shaft.

1 Additionally, or alternatively instead of providing a plurality of stacked turbine apparatus 2 associated with a generator at one or both ends of the common shaft. Each turbine 3 apparatus stage in the stack may have a generator where the shaft passes through the 4 generator. The system may comprise an assembly of turbine apparatus and generator stages stacked on top of each other in sequence all having a common shaft.

7 Figure 9 shows a system 300 having two apparatus 320 arranged in a stacked 8 configuration mounted on the same shaft 315. The system 300 is similar to the system 200 9 described in Figure 8 and will be understood from the description of Figure 8. However, in the system the 300 the lower apparatus 320b is inverted. The base of the upper apparatus 11 320a is connected to the base of the upper apparatus 320b. The apparatus 320a and 320b 12 are stacked back to back.

14 In this example the inverted apparatus 320b has a reverse blade arrangement which rotates in a different rotation direction to the blade arrangement in apparatus 320b. This 16 arrangement enables the system 300 to be omni-directional. The system 300 may be more 17 suited to an operation of the system in a horizontal plane such that the longitudinal axis of 18 the central shaft is parallel with the horizontal plane. It may also be suitable for use in high 19 density fluids (liquids) such as river flow or tidal flow.

21 In the above examples two apparatus are shown stacked on the same shaft. However, it 22 will be appreciated that the apparatus 220 may be considered as modular components of 23 the system 200 and the system may comprise any number of apparatus 220.

Figure 10 shows a system 400 mounted on a structure 460.The apparatus 420 is similar to 26 the apparatus 10 described in Figures 1A and 1B and will be understood from the 27 description of Figures 1A and 1B. However, the apparatus 400 has two generators 432a 28 and 432b connected to the shaft 415 to generate electrical energy.

29 In this example a first generator 432a is connected to a first end of the shaft 415 above the upper aerofoil 414 and a second generator 432b is connected to a second end of the shaft 31 415 below the lower aerofoil 416.

33 In this example each of the two generators 432a and 432b are connected to a support 34 frame 470. The support frame has a support arms 472a and 472b each connected to a generator. The support frame may be mounted to structure by conventional affixing means 1 such as welding or bolts. It will be appreciated that alternatively the frame may comprise 2 one arm connected to one generator to mount and support the system.

4 Although the apparatus described in Figures 1A to 10 are described as vertical axis apparatus mounted in the vertical plane, it will be appreciated that the apparatus may be 6 configured to mounted in the horizontal plane such that the longitudinal axis of the central 7 shaft is parallel with the horizontal plane. In a horizontal axis arrangement, the flow cavity 8 may be located adjacent to the port.

In the above examples described in Figures 8 to 10 the system comprises two generators 11 connected to the shaft 415 to generate electrical energy. It will be appreciated that these 12 systems may have one generator located at one end of the shaft and a bearing 13 arrangement at the opposing end of the shaft. It will also be appreciated that a support 14 frame and/or support arm may be connected to a bearing arrangement.

16 Additionally, or alternatively instead of providing a plurality of stacked turbine apparatus 17 associated with a generator at one or both ends of the common shaft. Each turbine 18 apparatus stage in the stack may have a generator where the shaft passes through the 19 generator. The system may comprise an assembly of turbine apparatus and generator stages stack on top of each other in sequence all having a common shaft.

22 Although the energy generation apparatus is described above has being configured as a 23 vertical axis turbine it will be appreciated that other orientations such a horizontal axis 24 turbine are possible within the scope of the invention.

26 Although in the above embodiment the upper and lower aerofoils are rotational coupled to 27 one another, in alternative configurations in the upper aerofoil may be stationary. In a 28 further alternative configurations, the shaft and plurality of blades may be connected to the 29 upper aerofoil and the lower aerofoil may be stationary.

31 The energy extraction system may be designed according to the requirements of the 32 specific location in which it is to be deployed. For example, in areas with a constant high 33 velocity fluid flow an apparatus having upper and/or lower aerofoil with a shallow slope 34 with a small angle to the horizontal plane may be used.

1 Alternatively, in areas with a constant low velocity fluid flow an apparatus having upper 2 and/or lower aerofoil with a high slope with a large angle (40 degrees or less) to the 3 horizontal plane may be used.

Optionally the shape or profile of the lower aerofoil and/or upper aerofoil may be 6 dynamically changed in response to different fluid flow conditions. For example, in a first 7 flow condition the lower aerofoil may have a generally low profile conical shape with 8 concave sides but in a second flow condition the lower aerofoil may have a high profile 9 cone-shape with concave sides arranged as the steeper incline or gradient..

11 The invention provides a system for extracting energy from a fluid flow stream comprising 12 at least one turbine apparatus. Each turbine apparatus comprises an upper aerofoil, a 13 lower aerofoil, a plurality of blades interconnecting the upper aerofoil and lower aerofoil, a 14 shaft, and a port in the upper aerofoil. The port may be configured to equalise pressure in a fluid volume between the upper and lower aerofoil.

17 The present invention relates to a system for the conversion of fluid flow energy in to 18 mechanical rotational energy for mechanical work and/or electrical generation, in particular 19 the invention provides a low profile aerodynamic or hydrodynamic drawn fluid flow, open environment non-laminar omni-directional mono-block through flow turbine apparatus.

22 The present invention overcomes problems of current turbine systems where fluid 23 movement from the upstream side of the turbine to the downstream side of the turbine is 24 restricted or hindered due to the internal turbulence and the profile of the apparatus.

26 As the apparatus enables the continuous fluid flow through the turbine the apparatus may 27 operate at greater efficiencies than conventional turbines. The apparatus may be 28 configured to allow through flow between the blades to mitigate or avoid downstream 29 turbulence.

31 The present invention provides an aerodynamic or hydrodynamic apparatus which 32 promotes flow over the apparatus mitigating flow separation, lift and drag. The 33 aerodynamic or hydrodynamic apparatus provides unobstructed paths through the turbine 34 which enables a constant fluid movement through the turbine whilst energy is extracted from the flow to turn the plurality of blades.

1 The arrangement of aerofoils, blades and/or pressure equalising port may minimise the 2 build-up of internal turbulence preventing the development of a vortex, cyclone or spiral 3 within the turbine body and enabling through flow.

By providing an apparatus that enables improved flow through the apparatus minimises 6 negative force acting on the blades. The constant fluid movement through the turbine from 7 the upstream side of the turbine to the downstream side of the turbine reduces the load 8 resistance such as drag forces, required to rotate the apparatus which enables the 9 apparatus to rotate when fluid flow speed is low. It also may minimise drag and turbulence downstream of the turbine and reduces the rotational vibration of the turbine apparatus.

12 The low profile aerodynamic or hydrodynamic drawn of apparatus and the arrangement of 13 aerofoils, blades and/or pressure equalising port may enable a reduction in the area of 14 downstream low velocity flow which may provide more effective use of fluid flow and reduce impact on multiple turbines in close proximity.

17 By adjusting or replacing the shape, slant angle, or profile of the upper aerofoil or lower 18 aerofoil may enable the apparatus to be operable in a range of different flow stream 19 speeds. The ability of the apparatus to be used in low and high velocity fluid flows enables it to be located and operated in a wide range of locations.

22 The present invention is an open environment turbine which does not require a shroud, 23 diverter, external housing, or duct to operate.

Throughout the specification, unless the context demands otherwise, the terms 'comprise' 26 or 'include', or variations such as 'comprises' or 'comprising', 'includes' or 'including' will be 27 understood to imply the inclusion of a stated integer or group of integers, but not the 28 exclusion of any other integer or group of integers.

Furthermore, relative terms such as", "lower", "upper, "up", "down", above, below, inlet, 31 outlet, upward, downward and the like are used herein to indicate directions and locations 32 as they apply to the appended drawings and will not be construed as limiting the invention 33 and features thereof to particular arrangements or orientations.

1 The foregoing description of the invention has been presented for the purposes of 2 illustration and description and is not intended to be exhaustive or to limit the invention to 3 the precise form disclosed. The described embodiments were chosen and described in 4 order to best explain the principles of the invention and its practical application to thereby enable others skilled in the art to best utilise the invention in various embodiments and 6 with various modifications as are suited to the particular use contemplated. Therefore, 7 further modifications or improvements may be incorporated without departing from the 8 scope of the invention herein intended.

Claims

Claims 1. A system for extracting energy from a fluid flow stream comprising at least one turbine apparatus wherein each turbine apparatus comprises: an upper aerofoil; a lower aerofoil; a plurality of blades interconnecting the upper aerofoil and lower aerofoil; a shaft; and a port in the upper aerofoil configured to equalise pressure in a fluid volume between the upper and lower aerofoil.
2. The system according to claim 1 wherein the plurality of blades is arranged to allow flow through the at least one turbine apparatus between the upper and lower aerofoils in a direction generally transverse to the longitudinal axis of the shaft.
The system according to claim 1 or claim 2 wherein the lower aerofoil and/or the upper aerofoil is connected to the shaft.
4. The system according to any preceding claim wherein the system comprises at least one generator and/or at least one mechanical device connected to the shaft.
5. The system according to any preceding claim wherein the port is configured to equalise pressure by allowing flow from the fluid volume between the upper and lower aerofoil to the exterior of the at least one turbine apparatus.
6. The system according to any preceding claim wherein the port is configured to equalise pressure by allowing flow from the exterior of the at least one turbine apparatus into the fluid volume between the upper and lower aerofoil.
The system according to any preceding claim wherein the port is located centrally on the upper aerofoil.
The system according to any preceding claim wherein the plurality of blades has an axis of rotation substantially perpendicular to a flow direction of a fluid flow stream.
9. The system according to any preceding claim wherein the plurality of blades, lower aerofoil and/or upper aerofoil is coaxial and/or rotationally coupled.
10. The system according to any preceding claim wherein the plurality of blades is configured to rotate the at least one apparatus about a vertical axis.
11. The system according to any of claims 1 to 9 wherein the plurality of blades is configured to rotate the at least one turbine apparatus about a horizontal axis.
12. The system according to any preceding claim wherein the at least one turbine apparatus comprises a flow cavity wherein the flow cavity is an unobstructed space in the at least one turbine apparatus.
13. The system according to claim 12 wherein the plurality of the blades extends from the periphery of the lower aerofoil and upper aerofoil to the flow cavity.
14. The system according to claim 12 or 13 wherein the flow cavity is located beneath or adjacent to the port.
15. The system according to any of claims 12 to 14 wherein the flow cavity is located at the apex of the lower aerofoil.
16. The system according to any preceding claim wherein the at least one turbine apparatus has at least one inlet and at least one outlet, wherein the at least one inlet and at least one outlet is located between the upper aerofoil and lower aerofoil.
17. The system according to claim 16 wherein the at least one inlet and the at least one outlet of the turbine apparatus is configured to be located generally transverse to longitudinal axis of the shaft.
18. The system according to any preceding claim wherein the upper aerofoil and/or lower aerofoil is selected from a variety of shapes including a convex sheet, a cone, dome, truncated cone, pyramid, a ring, a slanted or sloped ring or a raised disc.
19. The system according to any preceding claim wherein the upper aerofoil and/or lower aerofoil is set or sloped at an angle to a longitudinal axis of the shaft wherein the angle to the longitudinal axis of the shaft is in the range of 50 degrees to 85 degrees.
20. The system according to any preceding claim wherein the upper aerofoil, lower aerofoil and plurality of blade is an integral mono block unit.
21. The system according to any preceding claim wherein the at least one turbine apparatus is omnidirectional.
22. The system according to any preceding claim wherein the system comprises two or more apparatus.
23. The system according to claim 22 wherein the two or more apparatus have a stacked arrangement.
24. A method of extracting energy from a fluid flow stream, the method comprising: providing a system for extracting energy from a fluid flow stream comprising at least one turbine apparatus wherein each turbine apparatus comprises: an upper aerofoil; a lower aerofoil; a plurality of blades interconnecting the upper aerofoil and lower aerofoil; a shaft; and a port in the upper aerofoil configured to equalise pressure in a fluid volume between the upper and lower aerofoil; and disposing the at least one turbine apparatus in a fluid flow stream.
25. The method according to claim 24 wherein the at least one apparatus is configured to operate in a fluid flow stream having a minimum fluid flow speed of approximately 1m/s.