• 专利附录
  • 专利说明
  • 权利要求
  • 类似技术
  • 同族专利
  • 引用文献
  • 法律状态
  • 优先权
    • 专利摘要:
    ROTOR APPLIANCE. The present invention relates to a rotor apparatus for extracting energy from bidirectional fluid flows comprising a first rotor (7) mounted for rotation about an axis of rotation (4) in a first direction of rotation, in that the first rotor (7) having at least one helical blade (2) with a pitch that decreases in one direction along the axis of rotation (4); and a second rotor (8) mounted for rotation about the same axis of rotation (4) in an opposite direction of rotation and having at least one helical blade (2) with a pitch that increases in the same direction along the axis. of rotation (4), in which the fluid leaving the first rotor (7) is passed to the second rotor (8).
    公开号:BR112013018127B1
    申请号:R112013018127-3
    申请日:2012-01-20
    公开日:2021-05-25
    发明作者:Jason Dale；Aage Bjorn Andersen
    申请人:Sea-Lix As；
    IPC主号:
    专利说明:

    [0001] The present invention relates to a rotor to extract energy from a flowing liquid, for example, a tidal flow.
    [0002] A fluid that flows has kinetic energy due to its movement. Naturally occurring fluid flows can be found in tidal currents, coastal or ocean currents, river flows, thermal currents, air currents, and elsewhere. Fluid flows can also be man-made, directly or indirectly. For example, secondary fluid flows can be generated upstream or downstream from an obstacle placed in a naturally occurring fluid flow such as a dam in a river. Fluid flows can be generated by transporting a fluid in a pipeline or by a machine, such as fluid flows in a fluid system installed on a train, ship, or automobile.
    [0003] The conversion of energy from gas flows such as air currents, ie wind energy, is a well-developed technology. Numerous specially designed turbines were obtained to extract energy from the wind. However, the potential energy level is much higher in a liquid stream than in a gas stream because the fluid density is generally higher. For example, in tidal currents, fluid velocities of more than 5 m/s can be generated, although a more typical velocity can be in the range of 1.5 - 2.5 m/s. Due to the fact that the density of seawater is about 1,000 kg/m3, the energy density of tidal currents can typically be on the order of 4,000 W/m2. In comparison, the density of the air is about 1.2 kg/m3, so the energy density of wind at that speed is typically about 5 W/m2, and this is about 800 times less than that. available in a corresponding tidal current.
    [0004] Therefore, there is a need for an improved device for extracting energy from liquid flows such as tidal flows.
    [0005] Viewed from a first aspect, the invention features a rotor apparatus for extracting energy from bidirectional fluid flows, wherein the rotor apparatus comprises a first rotor mounted for rotation around an axis of rotation in a first direction of rotation, wherein the first rotor has at least one helical blade with a pitch that decreases in one direction along the axis of rotation; and a second rotor mounted for rotation about the same axis of rotation in an opposite direction of rotation and having at least one helical blade with a pitch that increases in the same direction along the axis of rotation, in which the exiting fluid from the first rotor is passed to the second rotor.
    [0006] Since the helical pitch of the helical blade is decreased in one direction, each rotor has an ideal flow direction, which varies from the larger pitch end to the smaller pitch end. The fluid that enters parallel to the longitudinal axis and goes to the end of the larger helical pitch must encounter less resistance and must be guided smoothly towards the rotor. When the fluid passes along the helical blade the decreasing pitch ensures efficient extraction of energy from the flow. The fluid can still flow parallel to the longitudinal axis and go in the non-preferred direction, but energy extraction should not be ideal as a lot of energy must initially be lost in aligning the incoming fluid flow with the angled rotor blades. Thus, rotors are conventionally designed with a preferred flow direction. In situations where the direction of flow is reversed, prior art arrangements can be provided with means to realign with the new direction of flow, such as a turret assembly or a float tied into a flow or a change in blade angle by some means.
    [0007] Preferably, the rotor apparatus is a generator rotor, and thereby a preferred embodiment comprises a generator that includes the rotor apparatus, for example a generator for generating electricity from tidal flows.
    [0008] The above two-stage bidirectional rotor comes from the non-obvious conclusion that when the fluid leaves a unidirectional helical blade rotor the fluid will have a longitudinal and radial component, and that this radial component will be well suited for end insertion of smaller helical pitch than another unidirectional helical blade rotor, when both rotors have blades that rotate in the same direction when pitch decreases (ie both rotors have clockwise blades when pitch decreases or both rotors have blades counterclockwise when step decreases). Thereby, in the second rotor the direction of fluid flow can enter through the end of the smaller helical pitch and flow to the end of the larger helical pitch. The resulting energy extraction must be the same as the initial case but in reverse, and the fluid must exit the rotor with only one longitudinal component. Since the two rotors are spinning in opposite directions and are opposed to each other, fluid can flow in the opposite direction with the same result. Thus, the two-stage rotor of this aspect allows energy to be extracted from flows in either direction along an axis without compromising the level of energy production. A preferred embodiment is a rotor apparatus for extracting energy from tidal flows, preferably by generating electricity, whereby the rotor apparatus functions as a tidal turbine. The invention can thus take the form of a tidal turbine comprising the rotor apparatus. Appropriate bidirectional liquid flow can also be generated due to the regular back and forth or up and down movement of a ship or an automobile.
    [0009] In a preferred embodiment, the first and/or second rotor(s) have an opening at the inlet or outlet end of the rotor apparatus that is arranged for axial fluid flow. Thereby, the opening is perpendicular to the axis of rotation of the rotor apparatus and the blades are preferably formed to receive or expel fluid flowing in a generally axial direction, optionally in an only axial direction. The larger helical pitch at the inlet and outlet end and thus receives mainly or only axial flow, which increases efficiency.
    [00010] Preferably, the first and second rotors have openings at their opposite ends that are not arranged for axial flow only, but can preferably be adapted to receive or expel fluid flowing with a radial component to its movement. The radial flux component is useful as the two opposite ends have a small pitch to the rotor blade and therefore the transfer of flux between the two rotors is most effective when the flux has a radial component as well as a axial component.
    [00011] A preferred embodiment does not allow fluid flow through either opening of the rotor when the fluid flow has only one radial component and no axial component.
    [00012] Preferably, the first and second rotors have opposite ends that are of the same diameter. The first rotor and/or the second rotor may be a cylindrical rotor having a blade formed by a cylindrical helix. However, in preferred embodiments the first rotor and/or second rotor have a blade or blades formed by a surface extending between inner and outer tapered propellers, each of the tapered propellers having a pitch that decreases as the helix radius increases. The rotors may have characteristics as discussed below in relation to the fourth aspect of the invention, for example with regard to the shape and shape of the conical propellers, the number of blades, the outer edge and the inner peripheral surface, the characteristics of the generator , and so on. In the preferred embodiment where the first rotor and the second rotor comprise a blade or blades formed between conical helices, the two rotors have large diameter ends opposite each other and are of the same diameter.
    [00013] The first and second rotors have ends opposite each other in such a way that fluid flows from one rotor to the other. Preferably, the opposite ends are directly opposite, i.e. with a minimal gap between the two rotors. This makes the best use of the radial component of flux that leaves one rotor and enters the other. However, in tidal turbine applications, to reduce the danger to aquatic life, the gap between the two rotors can be increased so as to reduce the shredding effect between the rotors. Then aquatic life can pass unscathed through the device by being carried longitudinally by the swirling flow.
    [00014] Preferably, the first rotor and the second rotor have a blade or blades of the same shape formed by similar conical propellers. This ensures maximum bidirectionality, since an identical fluid flow can enter the two-stage rotor apparatus from either end with the same resulting power draw.
    [00015] The rotor apparatus may comprise a casing around the first and second rotors. The casing preferably supports the rotors for rotation about the axis of rotation. The rotor housing can be designed to perform various functions. For example, the rotor housing can be designed purely to house the rotors and provide support through mechanical bearings, magnetic bearings or any other type of active or passive bearing system that allows the rotors to rotate freely with little friction. A sealing arrangement, such as lip seals, labyrinth seals, or some other type of sealing arrangement, may also be in place to prevent liquid flow from reaching the bearings or electrical components in the rotor housing. Or a portion of the liquid flow can be directed to the bearings and heat exchangers of electrical components and used as a refrigerant in applications that require it.
    [00016] The enclosure may also include generator parts, control systems and the like. Any suitable form of casing can be used. In a preferred embodiment, the rotor housing has an inlet section and an outlet section. Rotor casing can be used to enhance rotor performance. The rotor housing inlet geometry can be designed to increase the linear velocity of the liquid flow as it enters the rotor inlet through the use of a converging section or some other geometry. Since the available energy of the liquid flow is proportional to the cube of the velocity of the liquid flow, this provides an effective means of increasing the amount of available energy. The rotor housing outlet can also be designed to slow the flow of liquid in a controlled manner through the use of a diverging section or a specially designed outlet geometry so that turbulence and viscous losses are minimized and fluid is returned. smoothly to the main volume of fluid flow with minimal disturbance.
    [00017] Viewed from a second aspect, the invention presents a method comprising the use of a two-stage rotor apparatus as described above for the production of rotational kinetic energy from the flow of a fluid. Preferably, the method comprises using the two-stage rotor apparatus to produce energy from a tidal flow, and more preferably using the rotor to produce electrical energy from the tidal flow.
    [00018] Viewed from a third aspect, the invention presents a method of manufacturing a two-stage rotor apparatus, which comprises: assembling a first rotor for rotation around an axis of rotation, wherein the first rotor has at least one helical blade with a pitch that decreases in one direction along the axis of rotation; and mounting a second rotor for rotation about the same axis of rotation in an opposite direction of rotation, wherein the second rotor has at least one helical blade with a pitch increasing in the same direction along the axis of rotation.
    [00019] The method may include providing features of the rotor apparatus as discussed above with respect to the first aspect. The shape and shape of the rotor can be selected as discussed below in connection with the sixth aspect method.
    [00020] Seen from a fourth aspect, the invention presents a rotor comprising at least one blade arranged to rotate around an axis of rotation, wherein the blade is formed by a surface extending between inner and outer conical helices, where each of the conical helices has a pitch that decreases as the radius of the helix increases.
    [00021] In the present context, a conical helix is a three-dimensional curve formed on a surface of a generally conical body. The generally conical body surface can be conical, frustoconical, or any other shape formed as a rotating surface that has a generally increasing or decreasing radius. Thus, the surface is not specifically limited to a straight-sided cone, but instead may preferably be a convex-sided cone or frustocone, such as a nose cone or nose cone shape, or alternatively , the cone can be a cone or a frustocone with concave sides. What is important for the rotor of the invention is that each conical helix is formed with a radius that increases along an axis of the rotor and a pitch that decreases as the radius increases. The inner and outer tapered propellers preferably have the same decrease in pitch, although applications are possible where a different decrease in pitch for the inner and outer tapered helices can be used.
    [00022] The terms "internal" and "external" are used herein to refer to those parts of the rotor that are at a smaller or larger radius with respect to the axis of rotation of the rotor.
    [00023] The rotor is for extracting the kinetic energy of a liquid fluid flow or a system of liquid fluid flows by converting the kinetic energy in the liquid fluid flow into a force or torque of rotation, thereby enabling forward conversion in a more convenient form of energy, such as electrical energy. Preferably, the rotor is for generating electricity from tidal flows.
    [00024] There may be an outer rim located around the outer edge of the blade and corresponding to the surface on which the outer conical helix is formed. There may be an inner peripheral surface located around the inner edge of the blade that corresponds to the surface on which the inner tapered helix is formed. The rotor thus preferably includes inner and outer surfaces that include the blades, which may be the generally conical inner and outer rotating surfaces that correspond to the trajectories of the tapered propellers. Internally, the rotor thereby has one or more flow passages formed between the front and rear surfaces of the blade, the outer rim and the inner surface. The flow passages effectively contain the flowing fluid and prevent energy from being lost due to end losses.
    [00025] To allow rotation of the blade, the blade can be mounted on the outer edge and/or on the inner peripheral surface, which must then be mounted for rotational movement, for example, by means of bearings and a fixed mechanical shaft . In preferred embodiments, the blade is mounted to the outer rim and inner surface and extends between them. This ensures a closed fluid flow and minimizes tip losses. Alternatively, it could be possible for the blade to be mounted on only one of the outer rim and inner surface, with the other of the outer rim or inner surface remaining fixed. This latter arrangement can cause greater losses, but could simplify rotor fabrication.
    [00026] In a preferred embodiment, the rotor has an opening in a small diameter end of the rotor that is arranged for axial fluid flow. Thereby, the opening is perpendicular to the axis of rotation of the rotor and the blades are preferably formed to receive or expel fluid flowing in a generally axial direction. Preferably, the rotor has a large diameter end opening which is also perpendicular to the rotor's axis of rotation. However, in the preferred embodiment the vanes at the large diameter end are not arranged for axial flow only, but can preferably be adapted to receive or expel fluid flowing with a radial component in its movement. A preferred embodiment does not allow fluid flow through either opening of the rotor when the fluid flow has only one radial component and no axial component.
    [00027] The inner and outer tapered propellers preferably start at the same longitudinal position along the rotor rotation axis before extending along the direction of the rotor rotation axis. Preferably, the inner and outer tapered propellers also extend about the same axial length along the direction of the rotor's axis of rotation. With this arrangement, when an outer rotor rim is present, it naturally encloses an opening that requires an axial flow component for fluid to flow through the opening.
    [00028] The conical helix can be of any suitable shape that allows for a three-dimensional curve with an increasing radius and a decreasing pitch as described above. A preferred option is the use of an Archimedes spiral with a linear increase in radius, which can be used to produce a simple shaped rotor based on a straight-sided frustocone. However, the conical helix could alternatively be based on Euler, Fibonacci, hyperbolic, Lituus, logarithmic, Theodorus, or any other known spiral that has the variable radius r as a function of the polar coordinate θ, but which also has a third variable, the length l, which also varies as a function of the polar coordinate θ. Some curves and/or the use of nonlinear radius increase will result in conical helices based on conical shapes with convex or concave sides, as discussed above.
    [00029] The inner and outer conical helices can be based on the same spiral or curve shape, with different starting and ending radii. Alternatively, different curved or spiral shapes could be used for the inner and outer tapered propellers to produce a more complex shape for the blade.
    [00030] Although a single paddle can be used, it is advantageous to use multiple paddles. This creates multiple flow passages and also allows the rotor to be easily balanced. The choice of two, three or more rotor blades may depend on a balance between rotor strength, ease of fabrication and energy lost due to friction. In the present embodiment, three rotor blades are the preferred choice as they offer a strong, balanced three-point construction with minimal loss due to friction.
    [00031] The blade or blades are preferably formed as surfaces generated by straight lines between points on the inner and outer conical helices at the same longitudinal distance along the direction of the rotation axis of the rotor. In this way, the blade surface can connect the pair of conical helices in the radial direction. Alternatively, the blades can be formed as surfaces generated by curves between points on the inner and outer conical helices at the same longitudinal distance along the direction of the rotor's axis of rotation. With this arrangement, the surfaces of the blades can, for example, be concave when viewed from the large diameter end of the rotor.
    [00032] Both the inner and outer conical helices can increase in radius at the same rate, such that the conical surfaces are generally parallel. However, it can be advantageous to adjust the rotor performance by having a different increase ratio in diameter for the inner and outer tapered propellers. The inner conical helix may increase in radius at a slower rate than the increase in radius of the outer conical helix in order to reduce or restrict the hydrodynamic reaction forces and torsional forces produced by the rotor. Alternatively, the radius of the inner conical helix can increase at a faster rate than the radius of the outer conical helix in order to increase hydrodynamic reaction forces and torsional forces.
    [00033] The parameters discussed above, including the radius of the conical helix, the pitch of the conical helices and the relative increase in the radius of the inner and outer conical helices, are preferably linearly varied along the length of the rotor. However, non-linear variations of radius, pitch and relative radius may also be possible.
    [00034] In a preferred embodiment, the rotor includes a casing positioned around the outer rim. The housing can include the rotor and bearings or support or mechanical shafts that allow the rotor to rotate. The housing may include a converging inlet and/or a diverging outlet to condition fluid flow before it enters the rotor.
    [00035] The rotor can be provided with one or more generators to convert the rotating movement of the rotor into electrical energy. The rotating outer edge of the rotor can be arranged to act as the rotor in the electric generator where a part of a stationary housing is the stator. Alternatively, the inner peripheral surface can be arranged to act as the rotor in which stationary parts along the axis of rotation of the rotor provide the stator. With these arrangements, the rotor and stator form an electrical generator assembly that is driven by the liquid flow and directly converts rotor motion into electrical energy without the need to transfer the rotating force to an additional device. Permanent magnets or electromagnets can be mounted on the outer rim of the rotor and inside the rotor housing for this purpose. The formed stator and rotor can be configured in any appropriate manner to produce alternating current (C.A.) or direct current (C.C.) in an efficient manner. Electronic components and signal conditioning can be incorporated into the rotor housing or elsewhere to facilitate connection to a utility or storage facility such as a battery facility.
    [00036] However, the use of magnets is not considered ideal for low speed applications. In low flow velocity applications it is more efficient to have a large diameter rotor that can capture high levels of torque from the low velocity fluid flow. This results in a relatively low rotor rotation speed. A large number of magnets might be needed to directly generate the correct frequency for direct connection to a typical electrical grid. If a smaller number of magnets are used, then additional electronic equipment may be required to condition the electrical signal to match the electrical grid.
    [00037] Therefore, it is preferable to use multiple generators, of low torque, high speed, and high efficiency, such as asynchronous generators, which are useful in variable speed and constant frequency applications. High torque levels and low rotation speed are advantageous for this type of generator. Asynchronous generators can generate energy that can then be fed directly into the grid at the correct frequency.
    [00038] Since the rotor in this case can be a rotor with rotating peripheral inner and outer rims, large surface areas are available for connection to multiple generators of high speed and low torque. Preferred embodiments therefore require the use of these generators, rather than a single generator connected to a centrally rotating mechanical shaft. Several generators can be placed around the periphery of the rotating outer rim in order to extract the maximum energy and/or be placed in the inner central space of the rotor and extract energy from the rotating inner peripheral surface. The connection between the generator and either flange can be made with a simple gear or using a castor wheel.
    [00039] Since the outer rim and inner peripheral surface in preferred embodiments will have a diameter that varies along the length of the rotor, then multiple generators can be arranged to be connected to the outer rim or inner peripheral surface at different diameters to thereby rotate at different speeds of rotation with respect to the speed of rotation of the rotor.
    [00040] In a preferred embodiment, the outer rim and/or inner peripheral surface has a generally conical surface, and multiple generators can be movably mounted parallel to a conical surface to allow for variation of the input rotation speed generators by movement along the surface of the cone. This arrangement operates in a manner similar to some continuously variable transmission devices. Generators can be moved along the surface by appropriate framed and stepped motors. Generators can be mounted, for example, on the inner surface of the inner cone of the rotor, or on the outer surface of the outer rim of the rotor.
    [00041] In an alternative arrangement, multiple generators can be mounted on a stepped surface of the inner peripheral surface or the outer rim, that is, a surface comprising multiple stacked cylinders of different diameters. With this arrangement multiple generator rings can be mounted on a surface staggered to different diameters. One or more generator rings can preferably be coupled or uncoupled at different speeds of rotation in order to efficiently generate electricity for the different speeds.
    [00042] By enabling the variable speed connection to the rotor in this way, a relatively constant generator speed within the variable range of the generators can be achieved over a range of fluid flows.
    [00043] In a particularly preferred embodiment, a first rotor as described above is provided in combination with a second rotor as described above, with the large diameter ends of the first and second rotors opposite each other, in such a way that fluid leaves the large-diameter end of one rotor and then enters the large-diameter end of the other rotor. With this arrangement, the rotors are mounted for rotation about a single axis and are preferably arranged and mounted for counter rotation, i.e., in such a way that the first rotor rotates in the opposite direction around the axis relative to the second rotor. In this case, the rotors can have blades that are formed from conical helices that rotate in the same direction as the radius increases, that is, both the first and second rotors have blades that are formed in a clockwise direction as the radius increases. of the tapered propeller or, alternatively, both rotors have counterclockwise blades. Other possible features of a preferred two-stage rotor arrangement are discussed below.
    [00044] Viewed from a fifth aspect, the invention presents a method comprising the use of a rotor as described above for the production of rotational kinetic energy from the flow of a fluid. Preferably, the method comprises using the rotor to produce energy from a tidal flow, and more preferably using the rotor to produce electrical energy from the tidal flow, for example, in a generator.
    [00045] Viewed from a sixth aspect, the invention presents a method of manufacturing a rotor comprising at least one blade arranged to rotate around an axis of rotation, the method comprising: defining an internal conical helix and an outer conical helix, in which each of the conical helices has a pitch that decreases as the radius of the helix increases; and the formation of the blade(s) as a surface that extends between the inner and outer conical helices.
    [00046] The method may include the provision of rotor and tapered propeller characteristics as discussed above, including one or more of an outer rim, an inner peripheral surface, a mechanical shaft, a starting position and the length of the tapered propeller , the shape of the conical helix, the change in radius of the conical helix, the relative change in radius of the inner and outer conical helices, the change in pitch of the conical helix, the number of blades, the casing, the generators, the second rotor, and so on. In preferred embodiments, the method comprises selecting rotor characteristics based on the desired rotor performance characteristics. For example, the method may comprise selecting the rate of change of a radius of a conical helix or of both conical helices based on an output of the desired torsional force for a predetermined flow condition. The predetermined flow condition can, for example, be the average tidal flow at an intended installation location, and the desired torsional force can be combined with the ideal input torque for the intended output device, which may be a generator or multiple generators. Similarly, the method may comprise selecting the relative change in radius of the inner and outer taper helices or selecting the one-step change of a taper helix or both tapered helices based on a desired torsional force output for a condition of predetermined flow.
    [00047] The use of multiple generators of low torque, high speed and high efficiency mounted on the rotor with a surface that has a diameter that varies along the length of the rotor, in which the multiple generators are arranged to be connected to the surface at diameters to rotate in this way at different rotational speeds with respect to the rotational speed of the rotor is regarded as new and inventive in its own right and therefore, viewed from a further aspect, the invention presents a rotor for the generation of electrical energy to from a fluid flow, wherein the rotor comprises a surface having a diameter that varies along the length of the rotor, wherein multiple generators are mounted to receive the rotational force of surface movement at varying diameters thereof. The surface can be a generally conical surface or a stepped surface as described above. The term generally conical lends itself to referring not only to perfect straight cones, but also to truncated cones, convex cones, and concave cones as discussed above. Generators can be low torque, high speed and high efficiency generators such as asynchronous generators as discussed above. Several generators can be placed around the periphery of a rotating outer rim in order to extract maximum energy and/or be placed in a central inner space of the rotor and extract energy from the rotating inner rim. The connection between the generator and either flange can be made with a simple gear or by using a castor wheel or some other means. The rotor may have features as discussed above in connection with the rotor and the two-stage rotor apparatus. In a particularly preferred embodiment the generators can be movably mounted parallel to the generally conical surface to allow for variation of the input rotational speed to the generators by movement along the surface of the cone as discussed above.
    [00048] The invention also encompasses the use of the rotor described above for the production of electricity from fluid flows.
    [00049] Certain preferred embodiments of the invention will now be described by way of example only and with reference to the accompanying drawings, in which: Figures 1A and 1B show an embodiment of a rotor in a side view and an end view, Figures 2A and 2B show the rotor of Figure 1 with the outer peripheral rim partially detached so that more details of the rotor design are visible, Figures 3A and 3B are perspective views of the rotor of Figures 1 and 2 with the outer rim partially and completely omitted, Figures 4A and 4B show an alternative embodiment of a rotor in which the inner tapered radius of the propeller increases at a smaller rate than the radius of the outer tapered propeller, Figures 5A and 5B show an additional alternative where the radius of the propeller internal conical impeller increases at a ratio greater than the radius of the external conical helix, Figures 6A and 6B show an alternative mode where the helical pitch is decreased to a smaller rate than the rotor d Figures 1 and 2, Figures 7A and 7B show an alternative embodiment in which the helical pitch is decreased at a greater rate than the rotor of Figures 1 and 2, Figures 8A and 8B illustrate one embodiment of a two-stage arrangement of the rotor apparatus in a side view and an end view with the outer rim partially omitted, Figures 9A and 9B are perspective views of the two-stage rotor apparatus of Figure 8 with the outer rim partially and completely omitted, Figure 10 shows a two-stage rotor apparatus installed in a housing with generators on the outer surface of the rotor, Figure 11 shows a two-stage rotor apparatus installed in a housing with generators on an inner conical surface of the rotor, Figure 12 shows an alternative arrangement with generators on a stepped inner surface of the rotor, Figure 13 illustrates an arrangement with a pair of two-stage rotor apparatus installed in a pair tower-type structure. for use on the seabed, Figure 14 is a graph showing the variation in torsional forces generated by a two-stage rotor apparatus when the relationship between the minimum radius Do and the maximum radius Do of the conical helix is changed, the Figure 15 is a graph showing the variation in torsional forces generated by a two-stage rotor apparatus with modification in the ratio at which the radius of the inner conical helix increases compared to the radius of the outer conical helix, and Figure 16 is a graph showing the variation in torsional forces generated by a two-stage rotor apparatus when the rate of decrease of the helical pitch is adjusted by changing the rate of increase of the helical frequency.
    [00050] Figures 1A and 1B illustrate an embodiment of a rotor that includes an outer peripheral rim 1, the blades 2 and the inner peripheral surface 3. The rotor can be used to set the flow of a liquid in rotational motion, the which can then be used to generate electricity. For example, in a preferred embodiment the rotor is used in a turbine to generate electricity from tidal flows. The vanes 2 extend between the inner peripheral surface 3 and the outer rim 1 and thereby form enclosed flow passages. In this modality the underlying spiral that forms the shape of the blades 2 is based on an Archimedes spiral in which there is a linear increase in radius r with the polar coordinate θ. The resulting rotor, therefore, is shaped like a frustum of a cone. As noted below, other curve types can be used. Three rotor blades 2 can be seen inside the rotor and also the inner peripheral surface 3. The longitudinal axis of the rotor 4 is shown by a center line. Throughout the figures, the maximum outside diameter of the rotor is denoted by Do and the minimum outside diameter by do. The length of the rotor is denoted by L and the local length l is measured from the end of the rotor which has the minimum outside diameter o.
    [00051] Figures 2A and 2B illustrate the rotor of Figures 1A and 1B with the outer peripheral rim 1 partially hidden for clarity. The inner peripheral rim 3 is also highlighted. The three rotor blades 2 have a shape formed by a pair of conical propellers. The outer conical helix 5 is a helix formed on the inner surface of the outer rim 1 and forms a variable outer radius of the blade 2. The inner taper helix 6 is a helix formed on the outer part of the inner cone 3 and forms a variable inner radius. Pan. Both propellers have an increasing radius and a decreasing helical pitch along the longitudinal axis 4. Blades 2 have a decreasing helical pitch resulting from an increasing helical frequency. The pair of conical helices 5 and 6 is generated in a clockwise direction and has different initial radii that increase at an equal rate to form a pair of parallel conical helices.
    [00052] Figures 3A and 3B show perspective views of the rotor of Figures 1 and 2 in which more details of the shape of the blades 2 can be seen.
    [00053] Figures 4A and 4B show a variation of the rotor. In this mode the pair of conical propellers 5 and 6 are generated in a clockwise direction and form the shape of the blades 2 in the manner discussed above. However, the radius ri of the inner conical helix 6 increases at a smaller ratio than the radius ro of the outer conical helix 5 to thereby form a pair of non-parallel conical helices that are spaced further apart from each other at the large diameter end. of the rotor than on the small diameter end of the rotor.
    [00054] Figures 5A and 5B show a further variation in which the radius ri of the inner conical helix 6 increases at a rate greater than the radius ro of the outer conical helix 5, thereby forming a pair of non-parallel conical helices that are spaced even further apart at the large-diameter end of the rotor than at the small-diameter end of the rotor.
    [00055] Figures 6A and 6B show a further variation that has parallel inner and outer cones as in Figures 1 and 2, but in which the helical pitch decreases at a slower rate than the modalities previously described. This results in a slower rate of increase of the helical frequency. Figures 7A and 7B show the opposite variant in which the helical pitch decreases at a greater rate, which results in a faster rate of increase in the helical frequency.
    [00056] Figures 8A, 8B, 9A and 9B show a pair of rotors in a two-stage rotor apparatus that can function as a tidal turbine. Figures 8A and 8B are side and end views with the outer rim 1 partially omitted. Figures 9A and 9B are perspective views of the same pair of rotors with the outer rim 1 partially and completely omitted. As can be seen from Figure 8A, the two rotors are mounted end to end on a common rotating shaft 4. In use, the rotors rotate in opposite directions as described above. The rotors shown in the figures are similar to the rotors illustrated in Figures 1, 2 and 3 here, but it should be appreciated that the two-stage rotor apparatus could comprise any pair of rotors with the required helical blade shape, such as any of the modalities and alternative variations of the rotors described herein.
    [00057] Figure 10 shows an embodiment of a two-stage rotor apparatus that can function as a tidal turbine with a pair of counter-rotating rotors 7, 8 installed in a casing 9 along a common longitudinal axis 4. casing 9 is shown in cross section and rotors 7, 8 are shown in partial cross section. Rotors 7 and 8 rotate around a common fixed shaft 11 which is secured to housing 9 and supported by bearings 10. To ensure that flow only passes through rotors 7, 8, labyrinth seals 15 are placed in one or more. the other end of the rotors 7, 8 between an inner surface of the casing 9 and the outer surface of the flanges 1 of each rotor 7, 8. In this embodiment, the two ends of the casing 9 have a converging/diverging geometry 6 designed to increase/decrease the fluid speed and enhance the performance of the two-stage rotor apparatus.
    [00058] The two-stage rotor apparatus is used to accommodate a unidirectional flow and also a reversible or cyclic flow by combining two of the rotors. The first-stage rotor receives the oncoming liquid fluid flow that has a longitudinal component and extracts a proportion of kinetic energy by converting it into rotational force or torque, which causes the first-stage rotor to rotate. The second stage rotor has a geometry constructed in the same way as the first stage rotor and rotates around the same longitudinal axis as the rotor, but is rotated 180° with respect to the first stage rotor. Therefore, it rotates in the opposite direction around the axis. The liquid flow leaves the first stage rotor at an angle determined by the helical pitch at the rotor outlet and is then received by the second stage rotor, where the inlet to the second stage rotor is at a similar angle and helical pitch . At this stage the fluid has a longitudinal and a radial component. The second stage rotor extracts an additional proportion of kinetic energy from the liquid flow. When fluid exits the second stage rotor, it ideally has only a longitudinal component and can be returned to the main flow with minimal interference.
    [00059] In the embodiment of Figure 10, the housing 9 is designed to provide a mounting area for multiple generators of low torque, high speed and high efficiency 13 placed outside the rotors 7, 8. The generators 13 are driven by the movement of the flange external rotary 1 of the rotors 7, 8 by the appropriate gear.
    [00060] Figure 11 shows a cross section of an alternative embodiment of a two-stage rotor apparatus installed in a housing 9. In the embodiment shown in Figure 11, unlike the arrangement of Figure 10, the generators 13 are placed within the inner cone instead of the outer cone. Fixed mounting blocks 12 are joined to fixed mechanical shaft 11 within rotors 7 and 8. These provide a mounting area for multiple low torque, high speed and high efficiency generators 13. Generators 13 are driven by the inner surface of the Inner cone 3 of rotors 7, 8 by appropriate gear.
    [00061] As mentioned, in the present modality where the underlying spiral is based on an Archimedean spiral in which there is a linear increase in radius r with the polar coordinate θ, the rotor itself forms a shape similar to the frustum of a cone. A feature of this shape is that the linear velocity of the shoulder 3 varies along the longitudinal axis 4 due to a variable outer radius. Since the generators 13 in this mode are mounted on a block 12 with a surface parallel to the inner surface of the inner cone 3, the generators 13 can be moved along the surface by suitable framed and stepped motors 14. The generators 13 can be attached to a common moving frame assembly or be moved separately along the fruit surface by step motors activated by wired or wireless monitoring equipment and/or a CPU so that the two-stage rotor apparatus can respond to changes in the rotation speed of the rotors 7, 8 and adjust the longitudinal position of the generators along the frustum. This allows generators 13 to be moved within rotors 7, 8 to respond to changes in the rotational speed of rotors 7, 8. In this way, a relatively constant generator speed within the variable range of generators 13 can be achieved through a range of fluid flows. For low velocity fluid flow, the generator connection point can be made at the highest linear velocity end, and this is the larger diameter end of the rotor. For higher velocity fluid flows, the generator connection point can be repositioned at the lower linear velocity end, and this is the smaller diameter end of the rotor. This presents a significant advantage as a complicated gearbox is not required, which represents a significant savings in cost and complexity.
    [00062] Figure 12 shows a cross section of an alternative embodiment of a two-stage rotor apparatus installed in a housing 9. In the embodiment shown in Figure 12, unlike the arrangement of Figure 10, the generators 13 are mounted in a 16 fixed motor structure instead of outside the outer cone. Fixed motor structures 12 are joined to fixed shaft 11 within rotors 7 and 8. This provides a mounting area for multiple generators of low torque, high speed and high efficiency 13. Generators 13 are driven by the internal rotating surface. of the inner cone 3 of the rotors 7, 8 by the appropriate gear.
    [00063] As mentioned, in the present modality in which the underlying spiral is based on an Archimedean spiral where there is a linear increase in radius r with the polar coordinate θ, the rotor itself forms a shape similar to the frustum of a cone. A feature of this shape is that the linear velocity of the shoulder 3 varies along the longitudinal axis 4 due to a variable outer radius. Since the generators 13 in this mode are mounted on a fixed engine frame 16, the generators 13 can be installed as generator rings which can be coupled or uncoupled as required at different locations along the longitudinal axis 4. generators 13 can be coupled or uncoupled by stepping motors activated by wired or wireless monitoring equipment and/or by a CPU so that the two-stage rotor apparatus can respond to changes in the speed of rotation of the rotors 7, 8 and adjust the number of generator rings 13 in use at any time.
    [00064] This allows the generator rings 13 to be selectively coupled and uncoupled within the rotors 7, 8 in order to respond to changes in the rotational speed of the rotors 7, 8. In this way, a relatively constant output of the generator within of the variable range of generator rings 13 can be obtained over a range of fluid flows. Furthermore, the operation of the generator rings 13 outside their operating range can be controlled and it is clear that all generators can be disconnected if the two-stage turbine becomes overloaded in singular fluid flows.
    [00065] Generally speaking, for a low velocity fluid flow, the generator rings 13 can be coupled at the higher linear velocity end, and this is the larger diameter end of the rotor. For higher velocity fluid flows, generator rings can be coupled at the lower linear velocity end, and this is the smaller diameter end of the rotor. Coupling of multiple rings is also possible, for example coupling two or more generator rings at the lower linear speed end or two or more generator rings at the higher linear speed end. This presents a significant advantage over Figure 11, as a complicated positioning device is not required, which represents a significant savings in cost and complexity. Also shown in Figure 12 are the sealed compartments 17 that can incorporate the control gear for generators or flotation devices to allow safe recovery of the two-stage turbine to the surface for repair and maintenance.
    [00066] The two-stage rotor apparatus can be effectively applied to horizontal as well as vertical liquid fluid flow directions and those in between by varying the inlet and outlet orientation and the orientation of the rotors. In tidal turbine applications, the rotor housing also functions to direct liquid flow to the rotor to correct for small deviations in cross flow. For larger deviations from the transverse flow, the rotor housing can have a steering and suspension system and include vanes, gear and float control devices to adjust its position within a flow field to optimize performance or to the surface for maintenance purposes if it is submerged in a stream of liquid. The steering and suspension system provides a certain self-adjustment capability with respect to changes in flow direction.
    [00067] It is possible to have an additional two-stage rotor apparatus arranged or installed in series in the rotor housing. However, the amount of energy left in the liquid flow leaving the first two-stage turbine must be less than that contained in the original liquid flow. Therefore, it appears that it is more economical to have multiple two-stage rotor apparatuses in parallel.
    [00068] In operation, in particular in tidal turbine applications, the two-stage rotor apparatus can be supported on a floor, for example, the seabed, or it can be suspended in a liquid flow by means of a mooring or anchoring arrangement to the seabed or a floating raft. Or it can be seated in a tower installed on the seabed so that it can be retrieved from the sea for maintenance by a surface vessel or by a telescopic extension arrangement on the tower. Or it can be configured as being neutrally buoyant so that it sits suspended in the fluid flow, by modifying the unit's buoyancy, the two-stage turbine arrangement can be raised to the surface or lowered to the seabed. Or the entire turbine arrangement can be configured so that only a minor part of the arrangement has to be retrieved for maintenance. In this case only a sub-unit of the array containing the rotor and electrical components can be separated from the main installed frame, leaving the main installed frame in place. This provides a simpler maintenance operation.
    [00069] Figure 13 shows a possible use of the two-stage rotor apparatus as a tidal turbine. The rotors 7.8 in two casings 9 as shown in Figures 10, 11 or 12 are installed in a tower structure which can be installed on the seabed. The multiple rotor casings can be aligned with the main flow direction to allow effective operation in a reversible or cyclic flow such as a tidal stream system. Since the two-stage rotor apparatus is capable of efficient operation with flow in either direction, it is not necessary to provide a mechanism for rotation of the tower when the tidal flow changes direction.
    [00070] An alternative arrangement (not shown) would be to mount the two-stage rotor apparatus in an enclosure within a pipeline where the fluid flows. Fluid flow in either direction must be efficiently converted into rotational motion and, according to the preferred embodiment of the rotor, converted into electrical energy by generators. Piping can be installed within the canals of a dam or a hydraulic power station or a tidal barrage. Alternatively, one can stay within an enclosed liquid stream system consisting of two liquid reservoirs connected in such a way that transfer of liquid from one reservoir to the other is permitted. A flow of liquid can be induced between the two reservoirs as a consequence of externally applied natural or artificial forces. Such an external force can be experienced if it is installed transversely or longitudinally aboard a ship or some other mobile object such as a train or an automobile creating transverse and/or longitudinal movement.
    [00071] Thereby, rotors as described herein are used in preferred embodiments in a two-stage rotor apparatus installed in a rotor housing. When the two-stage rotor apparatus is subjected to a variety of liquid fluid flow scenarios, such as tidal flows, the rotors extract the kinetic energy of the liquid fluid flow and convert it into a rotating force or torque which causes the pair of specially formed rotors to rotate.
    [00072] In the preferred tidal flow mode, torque is applied to propel electric generators as indicated above. Alternatively, torque can be used to drive a pump, compressor or any other device that requires a rotational force or torque to be applied.
    [00073] The geometry of the rotors facilitates the conversion of kinetic energy in the liquid fluid flow into rotational force or torque. The rotor geometry is based on the pair of conical helices 5, 6 which have an increase in radius r with a polar coordinate θ along the longitudinal axis 4, where each helix 5, 6 has a different start radius. The pair of conical helices 5, 6 also has a pitch that decreases with the polar coordinate θ as the radius increases. The decreasing helical pitch provides an increasing helical frequency. This type of conical helix can be defined as a three-dimensional spiral that has the variable radius r as a function of the polar coordinate θ, but it also has a third variable, the length l, which also varies as the function of the polar coordinate θ.
    [00074] The pair of conical helices can be generated clockwise or counterclockwise and, as shown in Figures 6A to 7B, the rate of decrease of the helical pitch results in an increase in the helical frequency can be varied to obtain an ideal decrease in helical pitch per unit length. Other variables that have a direct effect on the extracted energy are the initial and final radii of the conical helix pair (and thus the minimum and maximum rotor inner and outer diameters) and the total rotor length. These can also be optimized for a given flow situation. For example, in a plumbing application, space may be limited and restricted to existing plumbing diameters, therefore a rotor having relatively small minimum and maximum outside diameters may be preferred, eg diameters of 1m and 2m respectively. . In this case, a longer rotor may be advantageous, which then allows room to extend the pair of conical propellers to optimize power output. In a tidal turbine application, space may not be an issue and large diameters, for example 10 m and 20 m respectively, can be used to greatly enhance the power output. A shorter rotor can then be used to reduce installation and roofing area costs.
    [00075] The surfaces of the rotor rotor blade are formed when the blades of the pair of conical propellers are connected to each other in the radial direction. In the rotors shown in the figures, three identical rotor blades 2 are present. Alternatively, there may be fewer blades or more identical rotor blades 2 spaced equally around the rotor. The rotor blades 2 extend between the inner peripheral surface 3 and the outer rim 1 and are fixed to the inner peripheral surface 3 or the outer rim 1 for rotation therewith.
    [00076] A hydrodynamic reaction force is created on a solid surface when a body of fluid flowing over the solid surface experiences a change in momentum. The hydrodynamic force of the liquid acting on the fluid body in a particular direction is equal to the rate of change of the fluid body's momentum in that direction as dictated by Newton's second law. According to Newton's third law, an equal and opposite hydrodynamic reaction force acts on the solid surface, delimiting the body of fluid. Examples of such hydrodynamic reaction forces are those found when a jet of water hits a wall, or the force felt in a piping system when the fluid is forced to bend, or the force felt in a solid body when placed in a fluid that flows, forcing the fluid to flow around it.
    [00077] In the rotors described here, a solid surface that delimits the body of fluid that flows is formed by the front and rear blades of a pair of rotor blades and the inner and outer edges of the rotor. As the fluid body flows through the specially shaped rotor and its complicated flow passages, it is constantly forced to change direction due to the shape of the blades and the decreasing helical pitch from inlet to outlet which result in an increasing helical frequency, thereby resulting in a continuous rate of change of momentum. This rate of change in momentum necessarily results in a hydrodynamic reaction force acting on the solid surfaces of the rotor. Due to the fact that the conical helix has a certain geometric direction, and this is either clockwise or counterclockwise, the hydrodynamic reaction force acts in the opposite direction and, since the center of the hydrodynamic reaction force is shifted to a radial distance from the longitudinal axis, a torsional force is generated, which acts around the longitudinal axis of the rotor and tends to rotate the rotor.
    [00078] The underlying mathematical spiral of the conical helix can be based on Archimedes, Euler, Fibonacci, hyperbolic, Lituus, logarithmic, Theodorus or any other known spiral that has variable radius r as a function of polar coordinate θ, but also has a third variable, the length l, which also varies as a function of the polar coordinate θ. Due to the reasons discussed above, it is apparent that an underlying spiral which has a faster change in inner and outer radius r with the polar coordinate θ must induce a faster rate of change in momentum which necessarily results in an increased hydrodynamic reaction force. This is the same as comparing a shallow curve to a sharp curve. It is well known that the force felt in a piping system is increased when the fluid is forced to rotate at the sharper of the two bends.
    [00079] In the modalities described above, for simplification purposes, the underlying spiral is based on an Archimedes spiral when there is a linear increase in radius r with the polar coordinate θ. However, it is equally feasible to construct the rotor by means of a non-linear increase in the inner and outer radii r with the polar coordinate θ through the use of a different underlying mathematical spiral such as Archimedes, Euler, Fibonacci, hyperbolic, Lituus, logarithmic , Theodorus or any other well-known spiral that has the variable radius r as a function of the polar coordinate θ, but also has a third variable, the length l, which also varies as a function of the polar coordinate θ. The use of an Archimedean spiral with linear increase in radii r with the polar coordinate θ provides a conical helix formed around a straight-sided frustocone as shown in the figures. On the other hand, a non-linear increase in the inner and outer radii r with the polar coordinate θ must provide a different shape, eg the outer and inner conical surfaces can be curved.
    [00080] In the preferred embodiments illustrated here, the pair of conical helices is chosen so that it has a linear increase in radii r with the polar coordinate θ along the longitudinal axis, each of which has a different initial radius. In some embodiments, such as in Figures 4A to 5B, the increasing radius of either conical helix may increase at greater or smaller ratios so as to form a pair of non-parallel conical helices. In other embodiments, such as in Figures 1A to 3B, they can increase at the same rate to form a pair of parallel conical helices. Simultaneously, the helical pitch is also decreased by varying I as a function of θ continuously or in distinct steps along the longitudinal axis 4. The rate of decrease of the helical pitch or the rate of increase of the helical frequency in the modalities of the figures are linear. Alternatively, they can be non-linear.
    [00081] The shape of the helix, the increase in radius and the decrease in pitch combine to provide the total hydrodynamic reaction force in the rotor and thus the torque and power output. These parameters can be optimized to maximize the extraction of energy from a given fluid flow or to limit the extraction of energy from a given fluid flow if this is required. The following set of equations considers the hydrodynamic reaction forces and the torques generated.

    [00082] As indicated in equation [1], the mass flux °m in the rotor is constant. The hydrodynamic reaction forces Fx, Fy and Fz are necessarily produced due to the continuously decreasing helical pitch or, in other words, due to a continuous change in the direction of the fluid flow and thus a change in the velocity components u, vew of the fluid between the velocity components in the first and second arbitrary cross sections in the rotor, where the first and second arbitrary cross sections are at different distances along the length of the rotor. This results in a rate of change of momentum and hydrodynamic reaction forces as expressed by Equations [2.1] to [2.3]. Observing the right-hand rule, the torques Tx, Ty and Tz around the x, y and z axes of the rotor are produced by the out-of-balance cross product of the hydrodynamic force components and the relevant distances x, y and z of the longitudinal axis around which they act as shown by Equations [3.1] to [3.3].
    [00083] According to this set of equations, it can be understood that a change in the rate of decrease of the helical pitch will result in an increase or a decrease in torsional forces and energy output. A decrease in torsional force is obtained by a slower rate of decrease in helical pitch and an increase in torsional force is obtained by a faster rate of decrease in helical pitch.
    [00084] The distance from the longitudinal axis at which the hydrodynamic reaction forces continuously act is increased or decreased by the change in radius of the pair of conical helices. For each complicated flow passage, a separate set of torsional forces results, where the total torsional force around the longitudinal axis of the rotor is the sum of all the torsional forces acting around the longitudinal axis of the rotor.
    [00085] In the case where the increasing radii of the pair of conical helices increase at the same rate to form a pair of parallel conical helices, this results in an equal increase in the distance from the longitudinal axis at which the hydrodynamic reaction forces act and thus an amplification of the torsional force and the energy output as determined by Equations [3.1] to 3.3]. In this case, the cross-sectional areas in the first and second arbitrary cross-sections in the rotor increase at a constant rate and, since the mass flow is constant, the speed differences and thus the hydrodynamic reaction forces produced are constant. The increase in torsional force and power output is only dependent on the rate at which the radius of the conical helix pair increases.
    [00086] Where the radius of the pair of conical helices increases at greater or lesser ratios so as to form a pair of non-parallel conical helices, this has the effect of changing the ratio at which the cross sectional areas in the first and second cross sections arbitrary in the rotor increases. When the inner conical helix increases in radius at a slower rate than the increase in radius of the outer conical helix, arbitrary cross-sectional areas increase at a faster rate. This has the effect of reducing changes in velocity components and, since mass flow is constant, the hydrodynamic reaction forces produced are lower. When the radius of the inner tapered helix increases at a faster rate than the radius of the outer taper helix, arbitrary cross-sectional areas increase at a slower rate. This has the effect of increasing changes in velocity components and, since mass flow is constant, the hydrodynamic reaction forces produced are greater. In this way, by manipulating the rotor parameters, it is possible to manipulate the extracted energy output and optimize or restrict it as necessary.
    [00087] Furthermore, the connection between the pair of conical helices is not limited to being straight. The connection can be curved, for example a concave surface can be used to increase the surface area across the surface of the specially formed rotor blade in order to spread the resulting hydrodynamic forces over a larger area and reduce internal stresses. Similarly, the pair of conical helices is generally axially aligned for simplification purposes, but may be slightly misaligned in order to change the surface characteristics of the conical helices in an advantageous manner.
    [00088] As discussed above, various rotor parameters and blade shape can be varied depending on the purpose of the rotor and the operating conditions to which it will be exposed, such as flow rate and so on. Figures 14 through 16 illustrate how changes in these parameters affect rotor performance.
    [00089] Figure 14 is a graph that illustrates the effect of varying the ratio between the maximum outside diameter of the rotor and the minimum outside diameter of the. In this case, the radii of the pair of conical helices are increased at the same rate to form a pair of parallel conical helices. The increasing diameter results in an increase in the distance from the longitudinal axis at which the hydrodynamic reaction forces act and thus provides an increase in the torsional force. The increase in torsional force is dependent on the ratio at which the radii of the conical helix pair increase.
    [00090] As a baseline, Figure 14 uses an array with no change in diameter, ie where the ratio of maximum and minimum radii [Do/do] is equal to one. This is a rotor in which the radii of the conical helix pair do not increase, ie this is a rotor based on a cylindrical helix and not a conical helix. The rotors described here, which are based on blades formed by conical helices, have a ratio of more than one, and this provides a multiplication of torque and an increase in efficiency as shown in the figure.
    [00091] In some of the variants discussed above, the inner and outer conical helices are formed on non-parallel conical surfaces. Figure 15 is a graph illustrating the effect of increasing or decreasing the relative radii of the pair of conical helices to form a pair of non-parallel conical helices. When the inner conical helix increases in radius at a slower rate than the increase in radius of the outer conical helix (ie, [Δri/L]/[Δro/L] < 1), the cross-sectional areas arbitrary to the first and second longitudinal distances along the rotor increase at a faster rate. This has the effect of reducing changes in velocity components and, since mass flow is constant, the hydrodynamic reaction forces and torsional forces produced are lower. When the radius of the inner conical helix increases at a faster rate than the radius of the outer conical helix (ie, [Δri/L]/[Δro/L] > 1), arbitrary cross-sectional areas within the rotor increase. a slower reason. This has the effect of increasing changes in velocity components and, since mass flow is constant, the hydrodynamic reaction forces and torsional forces produced are greater. The point where [Δri/L]/[Δro/L] = 1 is a rotor in which the radii of the pair of conical helices increase at the same rate to form a pair of parallel conical helices.
    [00092] Other variants discussed above involve the use of different pitch changes for the taper helix's decreasing pitch. Figure 16 is a graph illustrating the effect of changes in the rate of decrease of the helical pitch that results in a change in the rate of increase of the helical frequency Δf. As shown in the figure, a change of this nature will result in an increase or a decrease in forces and thus in torsional force output. A decrease in torsional force is obtained by a slower rate of decrease in helical pitch or a slower rate of increase in helical frequency and an increase in torsional force is obtained by a faster rate of decrease in helical pitch or by a faster rate of increase in helical frequency. In Figure 16, the rotor labeled Δf = 0.1 is based on the rotor shown in Figures 1A through 3B. In comparison, the rotor labeled Δf = 0.05 is based on the rotor shown in Figures 6A and 6B, whereas the rotor labeled Δf = 0.25 is based on the rotor shown in Figures 7A and 7B.
    [00093] In summary, the preferred embodiments described herein provide a compact low-complexity two-stage rotor apparatus that is ideal for generating electricity from tidal flow. The two-stage rotor apparatus can, however, be effectively applied to any liquid flow system which may have simple, reversible or cyclic liquid flow characteristics. The design of the rotors and blades can be tailored to a particular application by varying the parameters as described above. The parameters are not limited to the values and combinations of values presented here. Instead, the parameters can be varied alone or in combination as needed to obtain the desired performance characteristics. These features ensure that the two-stage rotor apparatus can operate efficiently under the significantly varied conditions and scenarios found in liquid fluid flows.
    权利要求:
    Claims (16)
    [0001]
    1. Rotor apparatus for extracting energy from unidirectional or bidirectional fluid flows, characterized in that the rotor apparatus comprises a first rotor mounted for rotation about an axis of rotation in a first direction of rotation, wherein the first rotor has at least one helical blade with a pitch that decreases in one direction along the axis of rotation; and a second rotor mounted for rotation about the same axis of rotation in an opposite direction of rotation and having at least one helical blade with a pitch that increases in the same direction along the axis of rotation, in which the exiting fluid from the first rotor is passed to the second rotor.
    [0002]
    2. Rotor apparatus according to claim 1, characterized in that the rotor apparatus is a rotor apparatus for extracting energy from tidal flows.
    [0003]
    3. Rotor apparatus according to claim 1 or 2, characterized in that the first and/or second rotor(s) have an opening at the input or output end of the rotor apparatus which is arranged to receive or expel fluid flowing in a generally axial direction.
    [0004]
    4. Rotor apparatus according to any one of claims 1 to 3, characterized in that the first and second rotors have openings at their opposite ends that are adapted to receive or expel fluid flowing with a radial component and also an axial component.
    [0005]
    5. Rotor apparatus according to any one of the preceding claims, characterized in that the first and second rotors have opposite ends that are of the same diameter.
    [0006]
    6. Rotor apparatus according to any one of the preceding claims, characterized in that the first rotor and/or the second rotor have a blade or blades formed by a surface extending between the inner and outer conical helices, in that each of the conical helices has a pitch that decreases as the radius of the helix increases.
    [0007]
    7. Rotor apparatus according to claim 6, characterized in that the two rotors have large diameter ends opposite each other and are of the same diameter.
    [0008]
    8. Rotor apparatus according to claim 6 or 7, characterized in that the first rotor and the second rotor have a blade or blades of the same shape formed by similar conical propellers.
    [0009]
    9. Rotor apparatus according to any one of the preceding claims, characterized in that it comprises a casing over the first and second rotors, wherein the casing is for supporting the rotors for rotation around the axis of rotation.
    [0010]
    10. Rotor apparatus according to claim 9, characterized in that the rotor housing has an input section and an output section, wherein the input geometry of the rotor housing is designed to increase the linear speed of liquid flow as it enters the rotor inlet, and the rotor housing outlet is designed to decelerate the liquid flow in a controlled manner.
    [0011]
    11. Generator characterized in that it comprises the rotor apparatus as defined in any preceding claim.
    [0012]
    12. Method, characterized in that it comprises the use of a rotor apparatus or a generator as defined in any preceding claim, for the production of rotational kinetic energy from the flow of a fluid.
    [0013]
    13. Method according to claim 12, characterized in that it comprises the use of the two-stage rotor apparatus to produce energy from a tidal flow.
    [0014]
    14. Method of manufacturing a two-stage rotor apparatus, characterized in that it comprises: assembling a first rotor for rotation about an axis of rotation, wherein the first rotor has at least one helical blade with a step that decreases in one direction along the axis of rotation; and mounting a second rotor for rotation about the same axis of rotation in an opposite direction of rotation, wherein the second rotor has at least one helical blade with a pitch increasing in the same direction along the axis of rotation.
    [0015]
    15. Method according to claim 14, characterized in that it comprises the provision of features of a rotor apparatus according to any one of claims 1 to 10.
    [0016]
    16. Rotor apparatus, characterized in that it is substantially as described above with reference to Figures 1A to 3B, Figures 4A and 4B, Figures 5A and 5B, Figures 6A and 6B, Figures 7A and 7B, Figures 8A to 9B, Figure 10, Figure 11 or Figure 12.
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    同族专利:
    公开号 | 公开日
    US20140017065A1|2014-01-16|
    ES2626269T3|2017-07-24|
    KR101890965B1|2018-08-22|
    MX336701B|2016-01-28|
    EA201391055A1|2014-11-28|
    CA2823971C|2019-03-12|
    EP2665903A2|2013-11-27|
    CA2823971A1|2012-07-26|
    WO2012098363A3|2012-09-27|
    CO6751266A2|2013-09-16|
    KR20140006877A|2014-01-16|
    GB201101010D0|2011-03-09|
    JP2014503048A|2014-02-06|
    CN103380276A|2013-10-30|
    EA030338B1|2018-07-31|
    PL2665903T3|2017-10-31|
    WO2012098363A2|2012-07-26|
    MX2013008357A|2013-11-04|
    EP2665903B1|2017-03-01|
    ZA201305750B|2014-10-29|
    BR112013018127A2|2016-11-08|
    GB2487404A|2012-07-25|
    JP6038809B2|2016-12-07|
    US9599090B2|2017-03-21|
    AP2013007052A0|2013-08-31|
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    法律状态:
    2018-12-18| B06F| Objections, documents and/or translations needed after an examination request according [chapter 6.6 patent gazette]|
    2019-12-31| B06U| Preliminary requirement: requests with searches performed by other patent offices: procedure suspended [chapter 6.21 patent gazette]|
    2021-03-09| B09A| Decision: intention to grant [chapter 9.1 patent gazette]|
    2021-05-25| B16A| Patent or certificate of addition of invention granted [chapter 16.1 patent gazette]|Free format text: PRAZO DE VALIDADE: 20 (VINTE) ANOS CONTADOS A PARTIR DE 20/01/2012, OBSERVADAS AS CONDICOES LEGAIS. |
    优先权:
    申请号 | 申请日 | 专利标题
    GB1101010.5A|GB2487404A|2011-01-20|2011-01-20|Rotor for extracting energy from bidirectional fluid flows|
    GB1101010.5|2011-01-20|
    PCT/GB2012/000056|WO2012098363A2|2011-01-20|2012-01-20|Rotor apparatus|
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