BR112017017356B1 - HYDROELECTRIC/HYDROKINETIC TURBINE AND METHODS FOR ITS MANUFACTURE AND USE - Google Patents

Abstract

HYDROELECTRIC/HYDROKINETIC TURBINE AND METHODS FOR THEIR MANUFACTURE AND USE. The application relates to unidirectional hydrokinetic turbines with an improved flow acceleration system that uses asymmetric hydrofoil shapes in some or all of the major turbine components. Components that may be in hydrofoil shape include, for example, the rotor blades (34), the center hub (36), the rotor blade guard (38), the accelerator guard (20), the annular diffuser(s) (40), the wildlife and debris deflector (10, 18), and the tail rudder (60). The method of manufacture designs various components to cooperate in optimizing power extraction, while other components reduce or eliminate turbulence that may adversely affect other components.

Description

Fundamentals of the Invention

[0001] The present invention relates to hydrokinetic turbines designed for the purpose of generating electricity and to methods for designing and using such turbines. It also relates to certain elements employed in hydrokinetic turbines. The turbines according to the invention are intended to be placed underwater, in a fixed, floating, anchored or towed configuration, in any location where the effective water current flows preferably with a minimum velocity of about 0.25 m/s. The flow or current of water may be of any type or source, although typically it will consist of one or more of the following types of flow or current of water: (a) fixed, floating or anchored in a continuous flow or current of water, as found, for example, in ocean currents, rivers or streams. (b) fixed, floating or anchored in fluctuating, alternating and/or cyclical flow or currents that may change direction periodically or irregularly, as found, for example, in tidal flow or seasonal flow. (c) fixed, floating or anchored in mechanically or naturally induced currents that are created, for example, by the filling and emptying of reservoirs, lakes, dams or locks. (d) The device may be towed through the water by a vessel or other device or method to artificially or effectively create a flow through the device.

[0002] The power of flowing water has been used by mankind for millennia to generate energy of various kinds for a variety of different purposes. It has been used to mill grain and drive belts in factory applications, and to mechanically drive various types of devices. Over the past 150 years, flowing water has proven to be very efficient for generating electricity in a number of different designs and applications.

[0003] The basic principle of using permanent magnets and copper coils to generate electricity is still being used today in many different forms, including the use of running water and water turbines to drive electrical generators and alternators.

[0004] Most ocean currents are caused by wind, which in turn is caused by Coriolis forces from the Earth's rotation. These currents are often influenced by the position of land masses that can deflect the flow and, in some cases, accelerate the flow.

[0005] Ocean currents can also be caused by density differences in water masses, temperature differences, or variations in water salinity. Ocean currents on this planet are probably the largest untapped source of energy in existence. River currents are also often used as a very good and efficient source of energy.

[0006] Since the beginning of technological development, there have been many different attempts to harvest this energy with varying degrees of success and efficiency. The currents that are most accessible and easiest to use for power generation are near-shore surface currents, ocean currents, and river currents. Water flow can also be produced artificially by building dams and creating reservoirs to accumulate large bodies of water that can be used on demand.

[0007] In 1882, the world's first hydroelectric power plant was on the Fox River in Appleton, Wisconsin. By 1889, 200 power plants had been built in the United States, and by 1920, hydroelectric power was used for 25% of U.S. electrical generation, which rose to 40% by 1940. Today, only 6 to 8% of U.S. electricity comes from hydroelectric power. There are vast opportunities and significant environmental and cost advantages to be gained by replacing conventional coal-fired power plants with hydroelectric facilities. Older hydroelectric facilities are primarily located within or below dams, using the pressure at the bottom of the dam to operate a water turbine that drives electrical generators.

[0008] Since World War I, the field of science now called fluid dynamics has developed tremendously and has become a very precise and finite science that is used today in the design of modern hydrofoils. Hydrofoils (as well as air profiles, also part of fluid dynamics) are used for a wide variety of purposes, including most designs in aeronautics, in motor vehicles, in watercraft, and in isolated elements used in hydrokinetic turbines.

[0009] Hydrokinetic turbines can be divided into different categories or types. For example, a turbine can be bidirectional or unidirectional. In the former case, the turbine is designed in such a way that it can be driven by a current flowing in both axial directions through the turbine, for example to be driven to generate power by both an incoming tidal flow and a retreating tidal flow. On the other hand, a unidirectional turbine is driven only by water flow in a single axial direction. From a hydrodynamic point of view, the design criteria for producing a bidirectional turbine are significantly more limited than in the case of a unidirectional turbine, i.e. all design criteria that have an adverse effect on the reversal of the direction of the fluid flow.

[0010] Another way to categorize hydrokinetic turbines is by their hub design, i.e., whether the central hub is closed or open. Traditionally, most hydrokinetic turbines have a non-rotating central hub (fixed relative to the outer hub of the turbine) that is closed or solid, and about which the rotor blades rotate. See, for example, examples from the following documents: U.S. 3,986,787 to Mouton et al., U.S. 4,221,538 to Wells, U.S. 4,313,711 to Lee, U.S. 4,421,990 to Heuss et al., U.S. 6,168,373 to Vauthier, U.S. 6,406,251 to Vauthier, and GB 2,408,294 to Susman et al. Some designs have a solid central hub but rotate around bearings between a radially outboard rotor ring and a turbine casing, as described, for example, in U.S. 4,163,904 to Skendrovic.

[0011] More recently, a company has developed hydrodynamic turbine designs in which an open central hub is provided for environmental reasons, i.e., to provide safe passage for marine creatures. See, for example, examples from the following documents: U.S. 6,957,947, U.S. 7,378,750, U.S. 8,308,422, and U.S. 8,466,595. In these essentially hubless designs, the rotor blades are typically mounted on the radial inside, on an inner ring member, and on the radial outside, on an outer ring member, and in some designs there is no inner ring member at all. These essentially hubless turbine designs are all bidirectional and are axially symmetrical in design.

[0012] In an adaptation of the open center concept, a type of hydrokinetic turbine is disclosed that is of the fixed center hub design cited above, but also includes a passage or opening in the center hub. See, for example, U.S. Pat. No. 2013/00443685 to Sireli et al., and U.S. Pat. No. 7,471,009 to Davis et al., both of which relate to a unidirectional turbine design. See also U.S. Pat. No. 7,874,788 to Stothers et al., and U.S. Pat. No. 2010/0007148 to Davis et al., which relate to specially configured bidirectional hydrokinetic turbines that include the optional use of an open center hub or, in the latter, a hub bypass opening, as in Davis et al. '009, noted above (see Fig. 7 of both).

[0013] US 4,219,303 A describes a power plant for generating electricity from the flow of water currents that uses turbine wheels inside nozzles submerged in the water current, anchored at the bottom of the watercourse, such as the ocean, and self-floated to a level well below the surface of the water.

[0014] Hydrokinetic power generation remains of great interest and has gained increasing importance along with solar power and wind power. Significant efforts are needed to design and build much more sophisticated and highly efficient hydrokinetic power turbines; however, since the process of refining turbine designs is in many ways unpredictable and therefore time-consuming, there has unfortunately been a tendency to simply build larger versions of existing turbine designs in order to obtain greater power output from them. New highly efficient turbines will allow greater amounts of energy to be extracted from a renewable source with virtually no environmental impact. For these reasons, further improvements to these turbines are strongly desired.

Summary of the invention

[0015] The present invention is defined by the features of the independent claims. Preferred embodiments are defined by the features of the dependent claims.

[0016] According to one aspect of the present invention, there is provided a unidirectional hydrokinetic turbine having a water inlet end and a water outlet end that define a direction of water flow through the turbine, comprising a generally cylindrical accelerator casing having a wall cross-section that defines within its cylindrical cross-section a water flow area that contains a structure located therein that consists essentially of an integral hydrokinetic force generating element comprising a central hub element having an asymmetric hydrofoil profile; and a plurality of blade elements mounted to the hub element, wherein the force generating element is mounted for rotation on the inner surface of the accelerator casing. Preferably, the hydrokinetic force generating element comprises a rotor assembly that further includes a rotor outer ring to which blade tips are attached and that has an outer circumference that is configured for rotation within the accelerator casing. Preferably, the hub member comprises a generally round profile member with an open center and wherein the wall members surrounding the open center form an asymmetric hydrofoil profile, the extrados (outer curves of the arc) being toward the outside of the turbine and the intrados (inner curves of the arc) facing toward the center of the hub. Furthermore, the blades preferably have an asymmetric hydrofoil profile-shaped cross-sectional configuration, with the blades most preferably having a cord length at their radially outer ends greater than the cord length at their radially inner ends and a profile/cord thickness at their radially outer ends that is greater than the profile thickness at the radially inner ends. It is preferred that the accelerator casing have a wall cross-section that is also asymmetric in shape.

[0017] According to other preferred embodiments, the unidirectional hydrokinetic turbine has a central hub having a length that extends both forwardly and rearwardly a substantial distance beyond the leading edges of the blades, and more preferably extending from the blades forward to a first point that is rearward of the water inlet end of the accelerator casing and extending rearward to a point at least as far as the water outlet end of the accelerator casing. Preferably, the central hub extends a total distance of about 50 to 80%, more preferably about 60 to 70%, and most preferably about 2/3 of the length of the accelerator casing.

[0018] According to other preferred embodiments, the unidirectional hydrokinetic turbine further comprises an annular diffuser comprising a generally cylindrical ring member having a wall cross-section comprising an asymmetric hydrofoil shape, said annular diffuser having a diameter larger than the diameter of said throttle guard and being positioned behind the main throttle guard, in the direction of water flow through the turbine, preferably in an overlapping relationship.

[0019] According to another aspect of the present invention, there is provided a unidirectional hydrokinetic turbine having a water inlet end and a water outlet end that define a direction of water flow through the turbine, comprising a generally cylindrical accelerator casing having a wall cross section comprising an asymmetric hydrofoil shape, wherein the hydrofoil shape comprises a generally S-shaped profile wherein the outer surface comprises a forward convex portion and a rearward concave portion that transitions into the forward convex portion and the inner surface comprises a rearward convex portion and a forward portion that has a shape that is straight or concave and transitions into the rearward convex portion; and a rotor assembly which is mounted for rotation within the accelerator casing about an axis which is generally parallel to the direction of water flow through the turbine, the rotor assembly comprising a plurality of rotor blades extending radially outwardly from the center of the turbine and being mounted for rotation within the accelerator casing. Preferably, the rotor assembly further comprises a central hub member, preferably having a generally round profile member with a hydrofoil profile, and the rotor blades are attached to the hub member. More preferably, the hub member comprises a generally round profile member with an open center and wherein the wall members surrounding the open center form an asymmetric hydrofoil profile, the extrados (outer curves of the arc) being toward the outside of the turbine and the intrados (inner curves of the arc) facing toward the center of the hub.

[0020] In some preferred embodiments, the rotor element further comprises an outer rotor ring to which the blade tips are attached and which has an outer circumference configured for rotation within the throttle casing. In other preferred embodiments, the unidirectional hydrokinetic turbine further comprises an annular diffuser comprising a generally cylindrical ring member having a wall cross-section comprising a wall cross-section also comprising an asymmetric hydrofoil shape, said annular diffuser having a diameter larger than the diameter of said throttle guard and being positioned behind the main throttle guard, in the direction of water flow through the turbine, preferably in an overlapping relationship.

[0021] According to another aspect of the present invention, there is provided a unidirectional hydrokinetic turbine having a water inlet end and a water outlet end that define a direction of water flow through the turbine, comprising a generally cylindrical accelerator casing having a wall cross-section comprising an asymmetric hydrofoil shape and defining within its cylindrical cross-section a flow area, wherein the shape of the hydrofoil serves to accelerate the flow of water through the accelerator casing and to create a negative pressure field behind the accelerator casing in the direction of water flow; a rotor assembly that is mounted for rotation within the accelerator casing about an axis that is generally parallel to the direction of water flow through the turbine, the rotor assembly comprising a generally elongated cylindrical central hub having a wall cross-section comprising a hydrofoil shape; a plurality of rotor blades attached to and extending radially outwardly from the central hub wall for rotation therewith and terminating in rotor blade tips, which blades have an asymmetric hydrofoil-shaped cross-sectional configuration; and an outer rotor ring to which the blade tips are attached and having an outer circumference that is configured for rotation within the accelerator housing; and an annular diffuser comprising a generally cylindrical ring member having a wall cross-section comprising an asymmetric hydrofoil shape. The annular diffuser has a diameter larger than the diameter of the accelerator casing and is positioned behind the main accelerator casing in the direction of water flow through the turbine, preferably in an overlapping relationship, whereby the hydrofoil shape of the annular diffuser serves to accelerate the water flow through the annular diffuser and to create a negative pressure field behind the annular diffuser, and in cooperation with the hydrofoil shape of the accelerator casing, the hydrofoil-shaped rotor hub and the blades, to increase the acceleration of the water flow through the accelerator casing at the location of the rotor assembly.

[0022] In some preferred embodiments of the unidirectional hydrokinetic turbine, the blades have a cable length at their radially outer ends greater than the cable length at their radially inner ends and/or the blades have a profile/cable thickness at their radially outer ends greater than the profile/cable thickness at their radially inner ends. In other preferred embodiments, the central hub comprises a generally round profile member with an open center and wherein the wall members surrounding the open center form an asymmetric hydrofoil profile, with the extrados (outer arc curves) facing toward the outside of the turbine and the intrados (inner arc curves) facing toward the center of the hub. Preferably, the center hub has a length that extends both forward and rearward a substantial distance beyond the leading edges of the blades, more preferably the center hub extends from the blades forward to a first point that is rearward of the water inlet end of the throttle housing and extends rearward to a point at least as far as the water outlet end of the throttle housing. Preferably, the center hub extends a total distance of about 50 to 80%, more preferably about 60 to 70%, and most preferably about 2/3 of the length of the throttle housing. It may also extend rearward beyond the trailing edge of the throttle housing.

[0023] According to another aspect of the present invention, there is provided a unidirectional hydrokinetic turbine having a water inlet end and a water outlet end defining a direction of water flow through the turbine, comprising a generally cylindrical accelerator casing section defining within the cross section a water flow; a rotor assembly that is mounted for rotation within the accelerator casing about an axis that is generally parallel to the direction of water flow through the turbine, the rotor assembly comprising a plurality of rotor blades extending radially outwardly from the center of the turbine, and a wildlife and/or debris deflector member mounted at the water inlet end of the accelerator casing, the deflector comprising a generally conical shaped structure that is tapered toward its forward/narrow end and comprising a set of deflector rods that run parallel to each other and are spaced essentially uniformly at a predetermined distance along their overall length relative to each other, whereby the predetermined distance defines the maximum size of wildlife or an object that may pass through the deflector. Preferably, the wildlife and/or debris deflector member includes at its forward/narrow end a ring member to which deflector rods are attached, the ring having a diameter no greater than the predetermined distance of the deflector rods. In other preferred embodiments, the ring member and/or at least some and preferably all of the deflector rods have a hydrofoil-shaped cross-section so as to reduce turbulence in the water flowing through the ring and/or the deflector rods.

[0024] According to another aspect of the present invention, there is provided a unidirectional hydrokinetic turbine having a water inlet end and a water outlet end that define a direction of water flow through the turbine, comprising a generally cylindrical accelerator casing having a wall cross-section comprising a generally asymmetric hydrofoil shape that serves to accelerate the flow of water through the main accelerator casing and to create a negative pressure field behind the accelerator casing in the direction of water flow, and that defines within its cylindrical cross-section a water flow area containing an integral hydrokinetic force generating element comprising a central hub member having an asymmetric hydrofoil profile and a plurality of blade members mounted to the hub member, wherein the force generating element is mounted for rotation on the inner surface of the accelerator casing. The turbine is characterized by its ability to accelerate the ambient flow velocity of water entering the turbine to a flow velocity at the blade members that is at least about twice the ambient flow velocity, preferably at least about 2% times, and more preferably at least about 3 times. Further, the turbine is characterized by its ability to provide an increase in power output compared to conventional hydrokinetic turbines of equal diameter by a factor of at least about 25%, preferably by at least about 50%, and more preferably by at least about 80%.

[0025] According to another aspect of the present invention, there is additionally provided a housing that is designed for use in a unidirectional hydrokinetic turbine having a water inlet end and a water outlet end that define a direction of water flow through the turbine. The accelerator housing comprises a generally cylindrical accelerator shield having a wall cross section that comprises a generally asymmetric hydrofoil shape, wherein the hydrofoil shape comprises a generally S-shaped profile in which the outer surface comprises a forward convex portion and a rear concave portion and the inner surface comprises a rear convex portion and a forward portion that has a shape that is either straight or concave. This unique configuration serves to optimally accelerate the flow of water through the main accelerator housing and to create a negative pressure field behind the accelerator housing in the direction of water flow.

[0026] According to yet another aspect of the present invention, there is provided a unidirectional hydrokinetic turbine having a water inlet end and a water outlet end that define a direction of water flow through the turbine, comprising a generally cylindrical accelerator casing having a wall cross-section comprising an asymmetric hydrofoil shape; and a rotor assembly that is mounted for rotation within the accelerator casing about an axis that is generally parallel to the direction of water flow through the turbine, the rotor assembly comprising a plurality of rotor blades extending radially outwardly

[0027] from the center of the turbine and the outer ring of the rotor to which the blade tips are attached for rotation in the accelerator casing, wherein the blades have an asymmetric hydrofoil-shaped cross-sectional configuration, with most of the blades having a cable length at their radially outer ends greater than the cable length at their inner ends and/or a profile/cable thickness at their outer ends greater than the profile thickness at their inner ends.

[0028] Preferably, the rotor assembly further comprises a central hub member, preferably having a generally round profile member with an asymmetric hydrofoil profile, and the rotor blades are attached to the hub member. More preferably, the hub member comprises a generally round profile member with an open center and wherein the wall members surrounding the open center form an asymmetric hydrofoil profile, the extrados (outer arc curves) being towards the outside of the turbine and the intrados (inner arc curves) facing towards the center of the hub.

[0029] According to yet another aspect of the present invention, there is provided a wildlife and/or debris deflector member that is designed for use in a hydrokinetic turbine. The wildlife and/or debris deflector member is designed to be mounted on one end or both ends of a turbine. The deflector comprises a generally conical shaped structure that is tapered at one end and comprises a range of deflector rods that extend parallel to each other and are spaced substantially uniformly apart at a predetermined distance along their overall length relative to each other, whereby said predetermined distance defines the maximum size of an object or wildlife that can pass through the deflector. Preferably, the wildlife and/or debris deflector member includes at its narrowest end a first ring member to which the deflector rods are attached, the first ring having a diameter no greater than the predetermined distance. Similarly, the baffle preferably has at or near its wider end a second ring member to which baffle rods are attached. In other preferred embodiments, at least some, and preferably all, of the baffle rods and/or rings have a hydrofoil-shaped cross-section.

[0030] According to another aspect of the present invention, there is provided a method for designing a unidirectional hydrokinetic turbine having a water inlet end and a water outlet end that define a direction of water flow through the turbine, comprising designing a generally cylindrical accelerator casing having a wall cross-section comprising an initial asymmetric hydrofoil shape and defining within its cylindrical cross-section a flow area, wherein the shape of the hydrofoil is selected based on fluid dynamics principles that serve to accelerate the flow of water through the accelerator casing and to create a negative pressure field behind the accelerator casing in the direction of water flow; designing a rotor assembly that is mounted for rotation within the accelerator casing about an axis that is generally parallel to the direction of water flow through the turbine, the rotor assembly comprising (i) a generally elongated cylindrical central hub having a wall cross-section comprising an initial hydrofoil shape that is selected based on principles of fluid dynamics; (ii) a plurality of attached rotor blades extending radially outwardly from the central hub wall for rotation therewith and terminating in rotor tips, which blades have an initial asymmetric hydrofoil-shaped cross-sectional configuration that is selected based on principles of fluid dynamics; and (iii) an outer rotor ring to which the blade tips are attached and having an outer circumference configured for rotation within the accelerator casing; the design of an annular diffuser comprising a generally cylindrical ring member having a wall cross-section comprising an initial asymmetric hydrofoil shape that is selected based on fluid dynamics principles, wherein the annular diffuser has a diameter larger than the diameter of the accelerator casing and is positioned behind the main accelerator casing in the direction of water flow through the turbine, preferably in overlapping relationship; and modifying the initial shapes of the annular accelerator hydrofoil, central hub, rotor blades and annular diffuser, in response to CFD testing/analysis of a turbine design comprising these components, so as to provide final hydrofoil shapes for all of these components that (a) at least improve and preferably optimize the ability to accelerate water flow through the annular diffuser and create a negative pressure field behind the annular diffuser and (b) provide cooperation with the final hydrofoil shapes of the accelerator casing, rotor hub and blades to at least improve and preferably optimize the acceleration of water flow through the accelerator casing at the location of the rotor assembly

[0031] Other features and advantages of the present invention will become apparent from the detailed description of the preferred embodiments which follows, when considered in conjunction with the accompanying figures.

Brief Description of Figures

[0032] The following is a brief description of the figures, which are presented for the purpose of illustrating the disclosure of certain embodiments of the invention presented herein and not for the purpose of limiting it.

[0033] Fig. 1 is a three-dimensional front view of an embodiment of a hydrokinetic turbine with support/mounting structure;

[0034] Fig. 2 is a three-dimensional rear view of the hydrokinetic turbine of Fig. 1, with support/mounting structure;

[0035] Fig. 3 is a cross-sectional side view of the hydrokinetic turbine of Fig. 1, with support/mounting structure:

[0036] Fig. 4 is a three-dimensional view of one embodiment of an accelerator housing with an annular diffuser;

[0037] Fig. 5A is a partial cross-sectional view of an S-shaped/double-curved hydrofoil accelerator housing in an arrangement as shown in Fig. 4, with annular diffuser;

[0038] Fig. 5B is a partial cross-sectional view of a non-S-shaped hydrofoil accelerator housing, in an arrangement as shown in Fig. 4, with annular diffuser;

[0039] Fig. 6 is a partial cross-sectional view of another embodiment of an accelerator housing, having multiple annular diffusers of similar diameters;

[0040] Fig. 7 is a partial cross-sectional view of another embodiment of an accelerator housing, with multiple annular diffusers of different diameters;

[0041] Fig. 8 is a three-dimensional view of one embodiment of an entire turbine with a central rotor section;

[0042] Fig. 9 is a cross-sectional view of the entire turbine of Fig. 8, with the central rotor section in place;

[0043] Fig. 9A is an isolated perspective view of the accelerator housing, schematically showing the placement of the coils

[0044] Fig. 10 is a three-dimensional view of the rotor section in isolation of the embodiment of Fig. 8;

[0045] Fig. 11 is a schematic side view of the rotor section of Fig. 8, showing one of the hydrofoil-shaped rotor blades, the rotor blade structure and the hydrofoil-shaped central hub;

[0046] Fig. 12 is a perspective view of four rotor blades in isolation in the embodiment of Fig. 8;

[0047] Fig. 12A is an isolated perspective view of a single exemplary rotor blade;

[0048] Fig. 13 is a cross-sectional view of one embodiment of a rotor blade illustrating certain preferred features, including variable angle of attack, variable cord length, and variable profile and twist thickness;

[0049] Fig. 14 is an isolated perspective view of a four-bladed rotor embodiment with cross-sections of the hydrofoil shapes of the blades;

[0050] Fig. 15 is a perspective view of a single rotor blade in isolation with cross sections of the hydrofoil shapes;

[0051] Fig. 16 is a perspective view of one embodiment of a turbine with front and rear debris and wildlife removers;

[0052] Fig. 17 is a cross-sectional view of the turbine of Fig. 16, with front and rear wildlife and debris removers;

[0053] Fig. 18 is a perspective view of the turbine of Fig. 16 having front and rear wildlife and debris removers and utilizing a hydrofoil/teardrop shaped deflector bar to form the removers;

[0054] Fig. 19 is an exploded perspective view schematically showing all components in partial cross-section in accordance with an embodiment of the invention;

[0055] Fig. 20 is an exploded view of the turbine of Fig. 19, showing all components in a schematic side view and partly in section;

[0056] Fig. 21 is a perspective view of one embodiment of a stack-mounted hydrokinetic turbine mounted on a rotating pedestal;

[0057] Fig. 22 is a cross-sectional side view of the stack-mounted hydrokinetic turbine of Fig. 21, installed on a rotating pedestal;

[0058] Fig. 23 is a schematic perspective view of the raft-mounted hydrokinetic turbine installed on an ocean barge, with both turbines operating;

[0059] Fig. 24 is a schematic perspective view of a raft-mounted hydrokinetic turbine installed on an ocean-going barge with the port side turbine and with a starboard side turbine in maintenance position;

[0060] Fig. 25 is a perspective view of the raft-mounted hydrokinetic turbine installed on an ocean barge, with the stirrup-side turbine operating and the port-side turbine in the maintenance position;

[0061] Fig. 26 is a perspective view of the hydrokinetic turbine mounted on a raft installed between two ocean barges;

[0062] Fig. 27 is a perspective view of the float in the installation of a hydrokinetic turbine installed on a submersible raft;

[0063] Fig. 28 is a schematic perspective view of a hydrokinetic turbine mounted on a structure installed on a bridge across a river;

[0064] Fig. 29A is a schematic perspective view of a floating hydrokinetic turbine installation mounted on a submerged raft installed on an ocean floor or riverbed;

[0065] Fig. 29B is a schematic perspective view of a floating hydrokinetic turbine installation directly attached to braces installed on an ocean or river bed;

[0066] Fig. 30 is a perspective view of one embodiment of a towed hydrokinetic turbine installation that is towed behind a vessel;

[0067] Fig. 31 is a perspective view of a hydrokinetic turbine having a solid hydrofoil-shaped central hub and hydrofoil-shaped vanes for attaching the hub, not forming part of the present invention; and

[0068] Fig. 32 is a schematic side view of a hydrokinetic turbine having a solid hydrofoil-shaped central hub and hydrofoil-shaped vanes for securing the hub, not forming part of the present invention;

[0069] Figs. 33A and 33B are, respectively, a schematic side view of an accelerator housing, diffuser and center hub initially selected for a 6-node stream and a corresponding view of an accelerator housing, diffuser and center hub that have been optimized for a 3-node stream;

[0070] Fig. 34 is a schematic side view and a front view of a rotor blade optimized for a 1.5 m rotor section diameter turbine to be used in a 3 knot current;

[0071] Fig. 35 is a more detailed schematic side view of an accelerator casing, diffuser and central hub optimized for a 1.5 m rotor section diameter turbine to be used in a 3 knot stream utilizing the rotor blade of Fig. 34.

[0072] Fig. 36 is a graph comparing the power output of hydroturbines according to the invention compared to similar machines not having hydrofoil casings, at varying water velocities.

[0073] Figs. 37A and 37B illustrate the results of two-dimensional tests of CFD analysis of flow acceleration, in velocity and pressure, respectively, of an embodiment according to the invention.

[0074] Figs. 38A and 38B illustrate CFD measurements, on velocity lines and pressure fields, respectively, of an embodiment according to the invention.

[0075] Figs. 39 and 40 show the pressure differential at the front of the blades and at the rear of the blades, respectively, in CFD tests.

[0076] Detailed Description of Preferred Embodiments of the Invention

[0077] The devices according to the invention are characterized by a single flow acceleration system and other single components, without a central shaft or gear and, as a result of these and other characteristics, can operate at a higher efficiency level than other comparable turbines.

[0078] The hydrokinetic turbine designs of the invention are readily scalable, meaning that they can be easily adapted and optimized for any specific geographic area and for different flow velocities and flow volumes.

[0079] The present invention includes several different installation methods, making the device suitable for use in many different types of locations and conditions with any navigable water depth.

[0080] The turbines of the invention are designed to be very environmentally friendly and have virtually no impact on marine life, the seabed or riverbed and its surroundings. They are preferably equipped with wildlife and debris removers, a safe passage or pathway for small marine animals and electromagnetic radiation (EMF) shielding. The exterior is preferably painted with a non-toxic anti-fouling coating.

[0081] Due to the unique design, materials used in construction and applied coatings, these devices require minimal maintenance.

[0082] The present invention, in one aspect, relates to a hydrokinetic turbine intended to be placed underwater, in a fixed, floating, anchored or towed configuration, in a water flow stream that preferably has a minimum flow velocity of about 0.25 m/s. The invention also relates to certain turbine components, a method for designing/producing such turbines, as well as a method for using them. Of course, this device will produce more power at higher flow velocities.

[0083] These turbines can be installed in any quantity. They can be used as single units or they can be installed as a "turbine array" or a "turbine farm" that can consist of multiple turbines and can number up to hundreds of units. The turbines can generate electricity in tandem or separately.

[0084] The design of these turbines is scalable and can be produced as a small unit of any size, but practically speaking, it is at least about 30 cm in rotor section diameter and can be any size of rotor section diameter that is practical and appropriate for a given application at a given location. The device can be a large unit of any size, up to at least about 30 m in rotor section diameter or more.

[0085] The invention provides an improved flow acceleration system developed by the applicant, which uses hydrofoil shapes in many of the major components of the turbine and more preferably in most or all of the components over or through which water flows. The components that may have a hydrofoil shape are named: the rotor blades (34), the central hub (36), the rotor blade casing (38), the accelerator casing (20), the annular diffuser (40), the wildlife and debris remover (10, 18), the tail rudder (60), the support structure (50, 52), the support stack (54). Some of these components, such as rotor blades or accelerator structure, may advantageously be hydrofoil shaped to optimize energy extraction, while other components, such as wildlife and debris removers, may be hydrofoil shaped to reduce or eliminate turbulence that could adversely affect another component or components.

[0086] The principles of hydrodynamics that apply to this design are valid for any size to which this hydrokinetic turbine is dimensioned and whatever the speed of the water flow. By appropriately changing the shapes of these hydrofoil profile shaped components, this hydrokinetic turbine can be adapted and optimized for the flow conditions of a specific site and for the size of the turbine required. The changes in the hydrofoil shapes are advantageously made to one or more of the rotor blades, the accelerator support, the central hub and/or the annular diffuser. The changes, which in some cases may be relatively small, may consist of increasing or decreasing the cable length and/or cable thickness of some hydrofoils and/or changing the angle of attack/incidence of the hydrofoils according to the speed of the water flow and the required size of the turbine. This means that the design of specific embodiments according to the invention may change relatively or even very little in appearance, but will function exactly the same regardless of the size of the turbine or the speed of the water flow, as long as the portions in size and position of the components relative to each other and the position between the individual parts are maintained and remain unchanged or very similar.

[0087] Turbine output will increase in proportion to the surface area of the rotor blades; this means that the driving force that determines how many kilowatts or megawatts a turbine produces is not proportional to its diameter, but in proportion to the surface area of the rotor blades exposed to the water current. Turbine output increases by the square of the diameter. In other words, a turbine that is twice as large in diameter will produce four times the electrical power. This design property makes the turbine scalable to almost any practical size and usable in a body of water with changes to the hydrofoil shapes, which are usually relatively minor changes.

[0088] The design and use of these particular hydrofoil part shapes not only eliminate the vortex from the rotor blade tips but also accelerate the water flow through the turbine rotor section due to the fact that the accelerator casing, in combination with the annular diffuser, creates a low pressure area at or behind the turbine outlet, preferably further enlarged by the hydrofoil-shaped central hub. These components together create a synergy to increase the water flow even further. The water flow that is already slightly accelerated at the turbine inlet through the encapsulation effect of the inlet channel is further accelerated by this low pressure area behind the turbine, which creates a suction to pull the water through the rotor section from behind at an even higher velocity. In the case of the preferred use of the hydrofoil shape of the parts, the figures according to the invention achieve a very large increase in the flow velocity through the turbine rotor section where the hydrofoil-shaped blades are positioned. No other known hydrokinetic turbine design has achieved this degree of flow acceleration.

[0089] The flow acceleration created by the unique shapes and combination of all hydrodynamic elements remains the same in any turbine size. Computational fluid dynamics analysis of hydrokinetic turbine designs according to the invention has proven that they accelerate the flow velocity through the rotor section to about three times the velocity of the ambient flow velocity surrounding the outside of the turbine. This means that, for example, if such a device were placed in a 3 knot current, the flow velocity through the rotor section of such a device would be up to 9 knots. The very significant advantages of this increased current for hydropower output are clearly evident.

[0090] The effects of each individual part, as well as the effects of the interaction/cooperation and relationship of the parts to each other, are described in detail below, in connection with several exemplary embodiments of the invention, with reference to the attached figures.

[0091] The invention preferably comprises four main components, a) a flow accelerator housing, b) an optional annular diffuser following the flow accelerator housing, c) a main rotor which is embedded in the accelerator housing but is a separate part, and d) one or more optional wildlife/debris removers. Some of these components typically comprise several different sub-parts which are assembled to be one part of the turbine. Additional features and advantages are described below. These parts and features cooperate with and have an effect on each other in ways which are also described below to produce the improved operation of turbines according to the invention.

Flow accelerator housing with annular diffuser

[0092] Referring now to Figs. 1-5, 8 and 19, the flow accelerator casing (20) is an important part that incorporates the more complex hydrofoil shape. As used in the designs of this invention, it preferably has an asymmetric hydrofoil shape and, more preferably, a double-curve/S-shaped hydrofoil shape (Fig. 5a, 21) or, in other words, a generally S-shaped double-curve configuration (Fig. 9) to create a negative pressure field behind the casing to accelerate the flow of water through the rotor section (30) of the turbine. The accelerator casing wall cross-section may also have a hydrofoil shape that is not a double-curve S-shaped shape but more closely resembles conventional hydrofoil shapes (Fig. 5b, 24). The accelerator casing accelerates the flow of water within the turbine compared to the ambient flow velocity around the accelerator casing. The accelerator casing preferably consists of four parts: the inlet runner (22), the stator housing (24), the rotor blade casing (38) (Fig. 10) and the rear casing (28). These four components together preferably form a single shape, which is preferably the asymmetric hydrofoil of the accelerator casing, which in certain preferred embodiments has the shape of an S-shaped/double-curved hydrofoil profile. All four parts are preferably joined together to form a perfectly smooth surface on the inside and outside, over which the water flows without creating any significant turbulence.

[0093] The inlet duct (22) serves to funnel the water flow into the rotor section (30) and to conduct the water flow to and over the stator housing (24) on the outside of the accelerator housing and over the rotor blade housing (38) on the inside. This outer surface and the inner surface of the rotor blade housing are part of the overall shape of the accelerator housing. The inlet duct also contains the forward thrust bearings that guide the rotor section during operation.

[0094] The stator compartment (24) contains all of the metal coils (25), preferably copper, that comprise the stator of the annular generator, as well as conventional electrical wiring (not shown) for transporting the generated electrical power away from the turbine. The stator compartment also contains the rotating bearings/ball bearings (or other low friction polymer bearings or bushings) (26) on which the rotor section rotates.

[0095] The outer surface of the rotor blade housing (38) is part of the accelerator housing, but is a separate part that is joined to the tips of the rotor blades (33) and rotates with the main rotor within the accelerator housing. It is described in more detail below.

[0096] The rear housing (28) located behind the stator housing (24) and the rotor blade casing (38) conducts the water flow to the outlet of the accelerator casing (20) and preferably has a feathered edge (29) at the rear end to prevent the creation of turbulence or drag. The rear housing also contains the rear/back thrust bearings (26) (Fig. 9) against which the rotor section is pressed as it rotates.

[0097] The annular diffuser (40) is also preferably an asymmetric hydrofoil shaped ring and preferably has a larger diameter than the throttle casing (20). The annular diffuser (40) is located behind the throttle casing and preferably overlaps somewhat over the rear end of the throttle casing (20). It functions in a very similar manner to the throttle casing by further increasing the negative pressure field behind the turbine. Due to the cooperation and resulting synergistic effect of the throttle casing and the annular diffuser, there is a further increase in the flow velocity through the rotor section. Generally speaking, at a relatively close position (e.g., about 4 to 6 inches) behind the trailing edge of the annular diffuser (end), which is preferably a feathered edge, the rear wildlife and debris exclusion portion is attached. There may be some instances where it may be advantageous, for example under specific water flow conditions, to employ one or more annular diffusers, such as the second annular diffuser (42) and perhaps even a third annular diffuser (44), positioned one behind the other. (Figs. 6-7) Rotor Assembly Turning now to Figs. 10-15, the hydrokinetic turbines of the invention preferably have an open center (37). This is advantageous in part in the figures of the present invention because the blades travel slowly through the water near the center of the rotor section and therefore do not create sufficient lift or sufficient energy to extract. In fact, the center portion generally has a negative effect on the rotor due to the extra resistance it creates from a wider wetted surface and the additional weight that must be displaced by the water. The tips of the rotor blades (34) travel through the water at a higher speed and therefore create substantially more lift and allow substantially greater energy extraction. Depending on the size of the turbine, the flow velocity at an installation site, and other site-specific requirements, the ratio of open center to blade and hub size can be anywhere from about 40% blade:60% open space to about 80% blade:20% open space. Turbines according to the invention advantageously use most of the overall diameter along the perimeter of the rotor section to produce lift, typically more than about 60% and more preferably about 2/3 of the diameter. This leaves the remaining smaller portion, e.g., in a preferred embodiment, approximately about 1/3 of the overall diameter at the open center (37). Eliminating the rotor center section reduces the overall weight of the rotor and also reduces the wetted surface area and drag that a solid profile section would create. Accordingly, the figures of this invention create a more efficient rotor section that utilizes a smaller blade area with less weight, less wetted area, and less drag, which can rotate at higher rpm rates and allow more energy to be extracted. There is also a side effect that is more beneficial to waste eliminator and wildlife which is described below.

[0098] The central hub (36, 80), which is preferably annular and surrounds the preferably open hub (37), is also used to join the rotor blade bases (39). (Figures 11-12 and 31) The solid central hub (80) preferably has a symmetrical hydrofoil shape, while the open-center central hub 36 preferably has an asymmetrical hydrofoil shape, with the extrados toward the outside of the turbine and the intrados toward the hub center. The lift generated by the central hub helps to increase the negative pressure field behind the turbine created by the accelerator casing (20) and the annular diffuser (40). This effect increases the acceleration of the water flow through the rotor blade section and contributes to the synergistic effect and resulting higher power generation.

[0099] The rotor blade casing (38) (also called the main rotor outer ring) is where the tips (33) of the blades (34) are attached. (Fig. 10). This rotor blade casing (38) forms a part of the hydrofoil shape of the accelerator casing (20). It is a separate element from the accelerator casing, allowing it to rotate with the rotor blades (34). But the surface of the rotor blade casing is preferably perfectly in line with the inner surface of the accelerator casing (20) to create a uniform curve of both the inner surfaces, the accelerator housing and the rotor blade housing. The outer surface of the rotor blade housing, which faces the inner surface of the stator housing (24), is preferably recessed into the accelerator housing and has a flat surface where the permanent magnets (32) are located which rotate through the copper coils (25) of the stator to produce electrical energy. The rotor blade housing (38) also eliminates tip vortex and reduces drag and turbulence, resulting in higher efficiency and greater power extraction.

[0100] Referring now to Figs. 11-15, the efficiency of the rotor blades (34) is preferably increased by utilizing an asymmetric hydrofoil shape, which is also preferably optimized as explained below. This shape, also called the cable or hydrofoil cross-section (35), results in an increase in the efficiency of each blade, reduces its size, and decreases the number of blades relative to other designs. A smaller rotor blade (34) has a smaller wetted area, thus producing less drag. The amount of lift generated by a hydrofoil shape is determined by the cable/cross-section (35) shape (Fig. 15), the cable length (74), and the cable thickness (76) of the hydrofoil (Fig. 13). In designs according to the invention, one or both of the cable length (74) and/or the cable thickness (76) preferably change between the blade base (39) and the blade tip (33). This optimizes the lift created by the shape of the hydrofoil in relation to the speed at which it moves through the water. The number of blades placed in the rotor section of the figures according to the invention may vary depending on the size of the turbine and the flow speed of the water in a particular application.

[0101] The angle/incidence (72) (Fig. 13) at which the rotor blades are installed is also a variable that can be adjusted in order to optimize the angle of attack or incidence of the blade moving through the water. It is preferred to use an optimum angle that is determined by the rotor rpm to produce a laminar or at least a near-laminar flow of water over the blade surface. If this flow is turbulent or significantly non-laminar, the hydrofoil creates less lift and therefore less energy can be extracted. The blade tip travels through the water faster than the blade base due to the fact that it travels a greater distance to complete one rpm. Therefore, the incidence of the blade advantageously decreases gradually from the blade base (39) to the blade tip (33) so as to be at the optimum angle. This change in angle is called the twist (78) of the blade. The twist is preferably designed to create maximum rotor blade lift at each cross section and therefore to increase efficiency and power extraction.

[0102] In order for the hydrofoil shapes according to the invention to be optimal while traveling through the water at different speeds, they preferably have different cable lengths (74) and different profile/cable thicknesses (76). Preferably, the blade thickness (76) increases and/or the cable length (74) increases from the base of the blade towards the blade tip, so as to increase the surface area where the blade travels through the water at the highest speed and creates the greatest amount of lift. Thus, the blades preferably increase in size and thickness as they extend radially from the hub. These increases in cable length and thickness result in greater efficiency and greater power extraction.

[0103] The hydrofoil shape of the rotor blades (35), the length of the cable (74), the thickness of the profile/cable (76), the degree of incidence (72) and the twist (78) of each rotor blade and the number of blades can be advantageously varied for each application in order to adapt to the specific flow conditions of the water site and other location needs.

Wildlife and Debris Removers

[0104] Referring now primarily to Figs. 16-18, a hydrokinetic turbine that produces energy from a renewable source with zero carbon emissions must be environmentally friendly, not only to natural resources and the atmosphere, but also to the marine environment and wildlife. This invention diverts and keeps all floating or submerged marine life and debris above a specified size out of the rotor of the hydrokinetic turbine of the invention. The size of marine life or debris that cannot enter the turbine nozzle section is specified by the spacing/distance (15) of the front and rear scrubber deflector rods (14). In this invention, the deflector rods, by design, are parallel to each other and are spaced evenly along their entire length so that there is no greater distance between the rods (15) in one place than in another. The spacing distance (15) is determined by the size and species of marine wildlife, as well as the size of debris encountered to be removed, and to suit the location needs of specific operating sites. This will prevent any marine life such as fish, turtles, marine mammals and even divers that are larger than the space (15) between the deflector rods (14) from entering the front hydrokinetic turbine rotor section, as well as the rear section when the front deflector is also used.

[0105] The present designs contrast with other known prior designs (see, for example, (US 3,986,787, US 2010/0007148 A1 and US D 614,560) that are characterized by baffle rods that are not parallel, such that the openings between the rods become larger/wider towards one end of the stripper, thus not limiting the entry of marine life or debris to a finite size. Some other prior art devices are designed as concentric circular baffle bars (see, for example, US D 304,322 and US 5,411,224) that define a finite opening size, but these configurations do not effectively discard all wildlife and debris, as do the baffle bars according to the present invention, which are aligned obliquely with respect to the direction of flow. In the concentric design, wildlife or debris can easily be housed between the rings. In the designs of the invention, the exact size of the marine life or debris to be excluded can advantageously be selectively predetermined by the distance (15) chosen between the deflector rods (14).

[0106] Ocean currents and river currents contain floating debris of various types. This debris may be floating on the surface or submerged at different depths. Therefore, it is preferable to keep such debris out of the rotor section of the hydrokinetic turbine to the greatest extent possible, to avoid damage to the turbine and to ensure continuous and uninterrupted electrical power. The designs according to the invention deflect and avoid all debris above the specified size (15) of the deflector rod spacing.

[0107] The hydrokinetic turbines according to the invention preferably have two wildlife and debris removers, one (10) at the front at the turbine inlet (22) and one (18) at the rear at the turbine outlet. The front wildlife and debris remover (10) is located at the front of the turbine protecting the inlet (22) of the accelerator casing (20) and is attached to the front end of the accelerator casing as well as preferably to the turbine support structure (50, 52). The deflector rods (14) of the remover may be made of metal, fiberglass or synthetic materials with different diameters depending on the size of the turbine; from about 1/4 inch in a small turbine and up to about 2 inches in very large units. The deflector rods preferably have hydrofoil/teardrop shapes (14) in cross-section (Fig. 18) with the blunt end pointing in the direction of the water flow and the sharp ends being the trailing edge. This configuration serves to prevent turbulence in the water flow that could disturb the efficiency of one or more other components, such as the accelerator casing (20), the annular diffuser (40) and/or the rotor blades (34).

[0108] The first/front wildlife and debris remover (10) is preferably constructed so that the baffle rods at the front end of the front remover (14) form a generally conical shape. The baffle rods at the front end are attached to a small ring (12) that preferably has the same inner diameter as the specified distance (15) between the inner parts of the baffle rods. At the rear end, the baffle rods are preferably attached to a large ring (16) that is preferably larger in diameter than the annular diffuser (40). The slope of the conical shape created by the gap between the front ring (12) and the rear ring (16), to which the baffle rods (14) are attached, can be changed to suit different environmental needs. The front skimmer is preferably positioned to slightly overlap the annular diffuser with a space that is approximately the same size as the distance (15) between the deflector bars, so as to maintain a finite size of wildlife and debris allowed to enter. It is designed to be conical in shape to shed and deflect any wildlife, debris, seaweed or anything else floating in the water stream about to enter the turbine.

[0109] The second/rear wildlife and debris remover 18 (Figs. 16 and 18) is located behind the turbine outlet and is attached to the trailing edge of the annular (end) diffuser. The rear remover also preferably consists of a net or mesh of parallel rod members spaced apart by the same predetermined distance as the rods (14) in front of the remover, and in the case of the front remover, the most preferred configuration is a generally planar one. The rear remover prevents larger marine life from entering the rear section of the rotor, even against the flow of the water current or also in the case of no current, such as during the change from an incoming to an outgoing tide. The deflector rods of the remover are spaced at the same specified distance (15) as the rear wildlife and debris remover in order to prevent wildlife and debris larger than the specified distance from entering the rotor section. All deflector rods (14) of both strippers preferably have a hydrofoil profile shaped cross section to minimize the creation of turbulence and vortices that negatively affect the hydrofoil shapes that may be present in one or more of the other components, such as the rotor blades, the accelerator casing, the annular diffusers and/or the central hub.

[0110] The smaller marine life that can pass through the space (15) of the deflector rods is advantageously provided a secondary route for safe passage through the cylindrical central hub (36) having an open center (37) in most of the turbine embodiments shown. The open center of the rotor section is described above. Since the velocity of the water flow in the center of the hub is faster than that outside, where the blades are located, the smaller marine life will be sucked through this opening and may escape unharmed. The diameter of the open center can vary widely without materially affecting the performance of the turbine. The optimum diameter can be calculated for each application and, in certain preferred embodiments, is typically approximately 1/3 of the total diameter of the rotor section. The accelerated flow of water through the open center (37) serves to safely transport small wildlife and small debris through the interior of the turbine.

[0111] No matter which installation method is chosen, the turbines according to the invention are preferably automatically self-orienting, meaning that they will always point exactly in the direction from which the water flow is coming. This is preferably achieved by installing behind the turbine a fixed tail rudder (60), which is preferably of hydrofoil shape and will orient the unit directly in the direction of the water flow stream. This feature enables the device to point exactly in the direction from which the stream is coming, so that the water passing over the hydrofoil-shaped components of the turbine flows at the optimum angle over all hydrofoil-shaped surfaces. This optimizes the pressure differential between the two sides, increases the synergistic effect of the hydrofoil shapes and contributes to a laminar flow of the water.

[0112] The design of the hydrokinetic turbines of the invention is such that the water flow is always in the same direction, i.e., it is unidirectional. This allows the turbines to have a great advantage over many asymmetric hydrofoil shapes and hydrodynamic effects which, when combined, result in a much more efficient turbine. Bidirectional turbines cannot use asymmetric hydrofoil shapes and are therefore less efficient.

[0113] The turbines according to the invention not only utilize the Venturi/Bernoulli effect much more effectively due to their unidirectional flow but also increase the flow velocity with the use of the preferred asymmetric hydrofoil-shaped accelerator casing and/or the annular diffuser and/or preferably the hydrofoil-shaped central hub.

[0114] The annular generator design preferably has magnets (32) mounted on the rotor blade shroud (38) and on copper or other metal coils (25) in the stator housing (24), which are preferably located within the accelerator housing (20). This design eliminates the need for hydraulic systems or a gearbox or transmission to mechanically extract and transmit power from the turbine. Gearboxes, transmissions and hydraulic systems create friction that consumes a portion of the power the turbine produces. By using an annular generator, the invention minimizes these friction/transmission losses and creates a more efficient turbine or generator. The electrical power generated directly within the turbine is transmitted through electrical wires (not shown) that eliminate friction/transmission and power loss. The power produced is then transmitted for conditioning to an inverter/transformer that is typically located outside the turbine where practical. The preferred design according to the present invention also eliminates the need for central bearings, which thereby eliminates the need for any fixed structure (e.g., a shaft or hub) located within the flow area through the turbine. The absence of any fixed structure, furthermore, means that no struts or other elements are required to support such fixed structure.

[0115] The accelerator casing (20), annular diffuser (40), central hub (36, 80) and rotor blades (34) of such a turbine are preferably constructed of composite construction materials such as, for example, carbon fibre, aramid fibre, fibreglass or the like in solid fibre and resin or in structural foam core material or honeycomb core material. Some parts, such as the stator housing, are preferably hollow so as to accommodate the copper coils (25) of the stator. Other parts, such as the inlet duct (22), the rear housing (28) of the accelerator casing (20) and the annular diffuser (40) may, in some preferred embodiments, be solid or of sandwich construction and remain empty inside, with the option of being selectively filled with water when submerged. With appropriate structural support (for the water depth) within the hidden parts, they will be able to withstand the pressure of the water when submerged. In the case of sandwich construction, these composite materials used are naturally buoyant and will keep the turbine afloat. While composite materials are ideal for the construction of this hydrokinetic turbine, the device can also be constructed of steel, aluminum, titanium, or other metal alloys deemed suitable for a particular application. The overall buoyancy of this turbine will be primarily positive and may use ballast to keep it submerged. The turbine can also be submerged by allowing hollow compartments to be filled with water. Installing an appropriate amount of ballast or filling certain compartments with water will allow the overall buoyancy of the turbine to be controlled to make the turbine positively buoyant, neutrally buoyant, or buoyant for different applications.

[0116] The preferred self-orienting characteristic of the device allows this turbine to be a unidirectional flow turbine. In a unidirectional turbine, the existence of a water flow that always comes from the front of the turbine allows the use of unidirectional or asymmetric hydrofoil shapes in the design. Accordingly, any or all of the basic components, i.e., the rotor blades, the accelerator structure, the annular diffusers, the hollow central hub, the tail rudder, and/or the wildlife and debris removers may advantageously comprise, to at least some degree, asymmetric hydrofoil shapes. Asymmetric or unidirectional hydrofoil shapes are much more efficient than symmetric or bidirectional hydrofoils.

[0117] The relationship and cooperation between the elements which may include the asymmetric hydrofoil shapes, i.e. the accelerator casing, the rotor blades, the annular diffuser, the hollow center hub, and/or the wildlife and debris removers, produces a mutually beneficial and synergistic effect which is enhanced as more of these elements are provided with the asymmetric hydrofoil profiles. In the most preferred embodiments, all five of these elements benefit from the presence of each other and when combined, their effect is magnified to create a much larger negative pressure field behind the turbine than they would create individually or separately. In other words, the effect of the plurality of elements together is greater than the sum of the plural elements individually. This synergistic effect creates greater acceleration of the flow through the rotor section where the asymmetric hydrofoil shaped blades gain greater advantage and are able to rotate at a higher speed or RPM. These combined effects result in a synergistic effect that is mutually beneficial and that results in a much greater efficiency that allows for greater energy extraction thanks to this "Flow Acceleration Technology" developed by the inventor.

[0118] Referring to Figure 36, the table shows how, for a preferred embodiment, the presence of the hydrofoil-shaped accelerator housing results in an exponential acceleration of the flow velocity through the nozzle section compared to the ambient flow velocity.

[0119] The data shown in Figure 36 illustrates the difference in power output at increased ambient stream velocity between 2 different hydrokinetic turbine designs with a 1.5 meter diameter rotor. The line of squares represents a hydrokinetic turbine that simply has a hub and 3 blades, without the casing (which is the most common design used in hydrokinetic turbines worldwide). The line of triangles demonstrates the output of the present invention, which utilizes the hydrofoil-shaped accelerator structure, annular diffuser, and open center hub. This is the same relationship for the same rotor assembly contained in an accelerator casing with a hydrofoil profile shape similar to that depicted in Figure 35. It can be seen that the power increase is in accordance with an exponential power on the order of 3. It can also be seen that in the lower range of current speeds (e.g., about 3 knots, which represents the vast majority of hydroturbine applications of this type), the comparative relationship is less sensitive to changes in current speed. Therefore, in this common range of operation, it is especially important to optimize the casing member design (and other components and relationships) to maximize the relative power increase.

[0120] Another way to demonstrate the increased efficiency of the turbines of this invention is by comparison with other highly efficient turbines available on the market. One of the most successful manufacturers and installers of hydrokinetic turbines in the world has recently developed a new hydrokinetic turbine design that it claims is the most efficient. It is a bidirectional turbine that has a 16 m diameter rotor section with an outer casing and an open center hub, and is claimed to be capable of producing 2.2 MW. Using the design methodology of the present invention, a turbine with the same 16 m diameter rotor section will produce 3.88 MW, according to our "theoretical calculations". This represents a 76% increase in electrical output for a turbine of the same size.

[0121] Below is a calculation used for power prediction for hydrokinetic turbine designs according to the invention:

Installation methods:

[0122] The hydrokinetic turbines according to the invention can be installed in virtually any moving body of water or can be moved through water to generate usable power. There are five main installation forms and deployment methods for such hydrokinetic turbines:

[0123] Pile Mount (Figures 21, 22): The turbine unit or units may be a pile mounted installation, consisting of a pile (52) driven into the ocean floor or riverbed that has a set of rotation bearings and a compression bearing on top (53). A larger pipe that is attached to the mounting frame (50) upon which the turbine positions the sleeves on the fixed pile (52) and bearings (53). The mounting frame (50) is detachable from the pipe (52) and has an electrical plug (53) inside the pipe that can be disconnected for maintenance and removal of the turbine. This installation allows the turbine to rotate and the turbine can freely rotate 360° to orient itself exactly in the direction of the water current. This type of installation also has a very small bottom footprint and minimal impact on the environment. In this installation, electrical energy is transmitted through a set of copper rings and carbon brushes (53) inside the sleeve to prevent a cable from being twisted and to avoid any restriction in the rotation action.

[0124] Floating Structure Mounting (Fig. 23, 24, 25,26, 27): The turbine unit or units may be attached to any type of floating structure such as an ocean-going barge, a barge (54), a ship or a vessel floating on the surface of the water. These devices may be anchored to the seabed or riverbed (59) or held in place by thrusters coupled to GPS tracking devices similar to oil rigs or attached to any structure in the ocean, on a river or along the coast. There are two types of raft-mounted installations, one is on a longitudinal pivot (Fig. 23, 24, 25) and the other is on a transverse pivot (Fig. 26, 27). Preferably, the raft-mounted device employs a hoisting system or a crane that is installed on the deck or a worm gear device to swing the turbine to the deck. One type of installation uses a single raft or barge, whereas a transversely mounted system uses two rafts or barges, with the turbine unit mounted between them. Depending on the size of the turbine, the location, or the operator's preference, one type of installation may be better than the other. For larger systems, it is often advantageous to use two rafts or platforms and mount the turbine between the two on the central transverse shaft (Fig. 26, 27), on which the turbine can be rotated 180° above the water for maintenance or repair. For smaller units, the turbine or turbines can be mounted on the side of the floating structure and pivoted on the longitudinal axis (Fig. 23, 24, 25), so that they can be placed on the deck of the structure for maintenance or repair.

[0125] Mounting on a land structure (Fig. 28): The turbine unit or turbine units may also be mounted on a land structure such as a seawall, a shoreline or be attached to a bridge pier or other structure installed in the flow of an ocean current or river current. The device may preferably be mounted on any of these fixed structures by at least two different methods. The support structure to which the turbine is attached may be mounted on one or two rails fixed to the fixed structure, on which the unit is lowered into the water and raised out of the water for maintenance or repair, or it may be mounted on a pivot which also allows the device to be pivoted into the water flow and out of the water for maintenance or repair. In either case, the units are held in place in the up position by a locking mechanism, while in the down position they may rest on a number of stops. The cable connection preferably takes place at the base structure and from there to a transformer for conditioning.

[0126] Floating Installation (Fig. 29): The turbine unit or units can be made naturally buoyant due to the composite construction materials that can be used for the construction of any or all of the parts. This allows the device to float at any depth determined by the length of a strap (64 and 66) that is attached to a marine base/mooring (59) or to a screw-type anchor or to any other device fixed to the seabed or riverbed. The two-part strap serves two purposes: the fixed strap (64) and the bearing strap (66) are to keep the device submerged at the desired depth and to transmit electricity from the generating unit to the base and then to shore. This belt (64 and 66) has 2 components: a primary fixed belt (64) which is a fixed extension between the turbine and the secondary bearing belt (66), which is a bearing mechanism that is attached to the base and has a length equal to the distance between the water surface and the desired depth where the turbine is to be kept. When the secondary belt is unwound, the turbine can float on the surface for maintenance or repair. The device can also be attached to a submersible raft (58) or submerged flotation device (58) to keep the turbine suspended in mid-flow. The same belt mechanism can be used in this case.

[0127] Towing installation (Fig. 30): The turbine unit or turbine units may also be towed behind a vessel or dragged through the water by other devices that propel the device through the still water, to artificially create a flow of water through the device. The tow cable is usually attached to the front of the wildlife and debris remover and thus guides the turbine to create the optimum flow from front to rear through the unit. Instead of the single rudder that is usually located behind the turbine outlet, there may alternatively be 2 or 4 winglets (62) attached to the outside of the annular diffuser; with one winglet on each side and one winglet each on the top and bottom. These winglets (62) prevent the turbine itself from rotating as it is towed through the water, thus ensuring that only the rotor section is rotating.

Maintenance procedures:

[0128] The hydrokinetic turbines of the invention require only minimal maintenance due to the design of the components and because the preferred composite construction materials are virtually corrosion-free. However, as with anything that is submerged in the ocean over a period of time, fouling and marine growth will occur. These hydrokinetic turbines are coated with non-toxic anti-fouling paints, but still require periodic surface cleaning to ensure optimum functionality and power. These units can be pressure washed by a diver while submerged, allowing them to remain underwater, or they can be brought to the surface and pressure washed by a ground crew. Other than periodic cleaning, these units require very little maintenance.

[0129] Depending on the type of installation, preferred maintenance procedures may vary, as discussed below.

[0130] In the case of a pile-mounted installation (Fig. 21, Fig. 22), it is preferable to use a special maintenance vessel (also designated by the applicant) which is a catamaran vessel with a removable deck between the two hulls and a gantry with a hoist installed on this removable deck. The vessel can be positioned above the turbine that needs maintenance, and the turbine unit can be lifted through the opening in the platform between the two hulls and lifting the turbine onto the boat. The electric wire connecting the turbine to earth leads to copper rings and brushes (53) that are located inside the pile support for rotation (52) has a waterproof plug (53) that can be disconnected when the turbine is lifted by the maintenance vessel located above. On the vessel, the turbine that has just been removed from the pile can be placed on one side in one of the hulls, and a ready spare turbine in the other hull can be lowered through the opening and connected and bolted back to the pile from which the first unit was removed.

[0131] In the case of a raft-mounted installation, it is preferable to attach the turbine support structure (50) longitudinally to the side of the raft or transversely between two rafts (Figs. 23, 24, 25, 26, 27). In each case, a support structure (55) is used which is mounted on pivot points with bearings (55) which allow the unit to rotate around a central axis of 270° in the case of longitudinally mounted units (Figs. 23, 24, 25) or 180° in the case of transversely mounted units (Figs. 26, 27). A locking mechanism is used to hold the units in place when submerged for power generation as well as when exposed for maintenance or repair. For surfacing of the unit, a crane or hoist (56) installed on the raft which can be attached to the turbine support structure is employed. Once released from the submerged position, the crane can pull the unit out of the water, rotating the unit into the maintenance position where it can be secured by locking into position.

[0132] In the case of a fixed structure mounted installation (Fig. 28), the turbine units can be maintained or repaired by at least two methods. One method is to have a floating platform or raft that is positioned after the turbine is lifted out of the water, either by sliding the turbine mounted on the support structure up on the rails of the fixed structure or by mounting the units on the support structure out of the water. The other procedure is to have a platform that is attached to the fixed structure that can move out of the way to lift the turbine units out of the water and then be repositioned for maintenance.

[0133] In the case of a floating installation, there are also at least two ways of maintaining the turbine units. In the case of a floating turbine that is moored to the seabed or riverbed by a fixed connection (64) that is joined to the running belt (66) can be extended by unrolling the traction mechanism (described in the installation description above) and bringing the turbine to the surface. Once on the surface, the turbine unit can be hoisted onto the deck of a vessel for maintenance or repair. In the case where the turbine units are attached to a submerged barge (58) or to a flotation device, the running belt traction mechanism (66) is unrolled in the same way as with a floating turbine and, once on the surface, the turbine units can be hinged onto the platform for maintenance.

[0134] In the case of a towed installation, the tow line attached to the turbine unit is hauled to bring the turbine unit alongside or behind the vessel, where it is typically retrieved by a hoist or a ship-mounted crane. The turbine is preferably placed on the deck of the ship for maintenance or repair.

Design methodology

[0135] The manner in which the turbine units of this invention have been designed is considered to be innovative and unique. After over 30 years of experience as a designer working in the field of fluid dynamics, and after having designed and built many different types of hydrofoils in his professional life, the applicant has arrived at the basic concepts underlying the design of the turbines according to the invention. With these basic design concepts, he believes that his turbine designs according to this invention provide hydrokinetic turbines that will outperform and surpass any other design currently in existence.

[0136] There are many environments today in which hydrokinetic turbines characterized by reversing current flow are used, and as a result, much of the modern design work has focused on providing bidirectional turbines that can be effectively employed in such environments, particularly tidal currents. Consequently, many of these bidirectional turbines incorporate small or nonexistent components, or if they do, the hydrofoil designs are necessarily symmetrical. However, the cross-sectional lift coefficient of an asymmetrical or curved hydrofoil is greater than that of a symmetrical hydrofoil. This design of unidirectional hydrokinetic turbines according to the present invention takes advantage of this phenomenon.

[0137] It was found that it made most sense to primarily optimize the hydrokinetic turbines according to the invention for a current of 3 knots (see, for example, the embodiment depicted in Figures 34 and 35), since currents of about 3 knots are the most common currents in ocean currents as well as in tidal currents and also in many river currents. There are also examples of locations and/or circumstances in which higher current speeds between about 5 knots and 7 knots are commonly encountered, for example in areas where special geographical features are present, such as, for example, fast-flowing tidal currents or river currents, or even ocean currents in rare cases, and also in the case of towing one of the hydroturbines behind a vessel, typically a sailing ship. To accommodate these higher current velocity situations, the application also describes design modifications for embodiments designed for a 6 knot current as being representative of and also exemplary turbines intended for use in environments exhibiting these higher current flow velocities. Thus, the application describes embodiments that are representative of designs for use in these two most common (i.e., nearly all) flow velocities. It is clear that, following the teachings of this application, turbines according to the invention can be optimized for any flow velocity, which from a practical standpoint includes currents ranging from about 100 knots to up to 12 knots flow velocity.

[0138] There are many standard algorithms used in fluid dynamics to calculate hydrofoil shapes, and standard manuals and databases contain comprehensive information and tables relating to such calculations and known designs. These need not be discussed in the present context since they are well known to those skilled in the art. However, as discussed below, in some embodiments, the present invention utilizes these algorithms/databases in a novel design scheme as a starting point for devising novel hydrofoil shapes that serve as so-called "starter" designs in the early stages of the hydroturbine design process.

[0139] In one embodiment, the design process typically begins with hand-drawn sketches (usually, but not necessarily, new) based on conventional fluid dynamics considerations, which sketches are selected based on the new principles according to this invention. The selected sketches are then input into a computer program of the type called a 3-D modeling program, an example of which is called "Rhino 3-D" or "Sol id Works". This results in a first version of the "initial" designs.

[0140] Alternatively, the first version of the "initial" design may be produced by selecting different hydrofoil shapes from a database, such as the National Advisory Committee for Aeronautics (NACA) files, again based on the same conventional fluid dynamic considerations that are employed in producing the hand-drawn sketches, but again the shapes are selected (from a large number) based on the innovative design considerations taught in this application. The shapes of this first version, the intuitive "initial" hydrofoil shapes (however arrived at) are modified with 3-D modeling software such as Rhino 3D or SolidWorks, and analyzed in a 2-D flow analysis program such as "Java Foil" or similar, and other commercially available software products for this purpose. This modification proceeds by viewing the selected "initial" profiles in 3-D and making modifications deemed favorable based on fluid dynamics considerations, so as to maintain laminar flow and avoid turbulence while maintaining maximum flow velocity. As a result of this first step, modified "initial" designs are created that represent new and unique hydrofoil shapes in accordance with the principles of the invention, which are then made into an annular or nozzle shape for use in a hydroturbine context.

[0141] Generally, when considering the design for a single selected current speed, such as 3 knots, the size of the hydroturbines according to the invention can be enlarged or reduced with only minor changes in the overall configuration. The main factor influencing the choice of an "initial" hydrofoil shape and therefore the further modification of this profile is the water current flow speed at which the turbine is to be placed. At higher flow speeds, such as 6 knots for example, the cross-section of the hydrofoil shapes is generally thinner and smoother (less chamber on both sides of the hydrofoil), so they are in a profile for a 3 knot current, where the hydrofoil cross-section would be more curved and thicker (more arched on both sides of the hydrofoil). This is illustrated generally in Figure 33, where the differences in the respective cross-sections or profiles are clearly visible. At higher flow velocities, the hydrofoil shape cable is also typically lengthened. This is also visible in Figure 33, where in Figure 33a the modified “initial” designs for the center hub and throttle housing are more elongated when designed for use in a 6-knot current than in the case of a similar configuration designed for use in a 3-knot current, as shown in Figure 33b (which, however, is not an “initial” design, but rather a final design resulting from the second step of the design process, as described below). These modifications (performed in 3D modeling software) are always made to create optimal lift and maximum acceleration at the flow velocity. With the modified “initial” design of Figure 33a, which is somewhat intuitively designed in the first step of the process, as discussed above, it is now possible to move on to the second step of the design process (discussed below) where the modified “initial” design is subjected to more quantitative optimization using CFD analysis.

[0142] The rotor blade shape is designed in the same manner as the central hub and accelerator casing. Thus, a suitable "starting" hydrofoil shape is sketched or selected from the library for the rotor blade cross section according to the principles of the invention, and then modified (using fluid dynamics principles) based on the speed at which it travels through the water, which speed is greater at the blade tip than at the blade base. Accordingly, the rotor blade hydraulic profile cross section, cable length, cable/profile thickness, and cross section incidence preferably change, and more preferably change continuously, from the blade base to the blade tip. During the first step of the design process, as many modifications as possible are made by intuitively applying fluid dynamics considerations to arrive at a modified "starting" design. As understood by those skilled in the art, this is usually done with the help of software products designed to assist such design activities, such as, for example, the programs called "JavaProp", "QBlade" and others. (The variations described herein can usually be visualized by looking at the preferred final or "optimized" embodiment illustrated in Figure 34, which represents a rotor blade profile that is "optimized" (in the second step) to a 1.5 m diameter rotor blade section, for use in a 3 knot current. It is clearly visible how all the parameters defining the hydro shape of the blade and its incidents change between the base and the tip of the blade.

[0143] Referring to Figures 37A and 37B, the former shows the acceleration of the flow at 2-D velocity, indicating a high velocity zone within the turbine (95), resulting from the software analysis, while the latter is a related presentation showing the acceleration of the flow at 2-D pressure. Both figures clearly show areas of enhanced acceleration resulting from the design features according to the invention.

[0144] Moving now to the second stage of the development process, these modified "initial" shapes created in the first stage of design are then analyzed for their efficiency in working together in a turbine environment to create the highest pressure differentials and lowest turbulence to achieve maximum acceleration of water flow through a nozzle. This is the "optimization" stage, where the final, optimized shapes are determined for each of the hydrofoil components. For this analysis, what is called Computational Fluid Dynamics (CFD) is used. As is known, this testing is always done in a three-dimensional structure. These simulations can be done in any known CFD computer program, such as one called "STAR CCM+", which is one of the most advanced software in this field. This software allows the designer of an intuitively created hydrofoil shape to analyze and optimize the flow characteristics in a virtual environment before building prototypes for real-life testing.

[0145] The following is an example of the results, from a solver program, of the 3-D CFD analysis performed for an initial design of a throttle casing and center hub with annular diffuser. Referring to Figure 38A, the pressure differential within the turbine as a result of the acceleration of the flow is represented by the display of streamlines. This is also used to determine if there is any turbulence in the water flow that could reduce efficiency. Referring to Figure 38B, the pressure fields resulting from the flow streamlines shown in Figure 38A are shown.

[0146] These examples of CFD analysis of an already partially optimized accelerator housing and center hub, with the annular diffuser added, demonstrate a synergistic effect of the elements that creates a much larger pressure differential.

[0147] In CFD, the program creates an elaborate mesh of polyhedral shapes to simulate the fluid volume and a very precise turbine shape in the form of a mesh composed of millions of triangles. This newly created model is then run through the program's solver, which analyzes the fluid/water flow (polyhedral bodies) over the turbine shape (triangular mesh) and displays the flow paths created by it. In this way, the final optimized shapes and component configuration are achieved by making changes and evaluating the consequences of these changes based on the test feedback provided by the CFD analysis, until a final optimal combination of shapes is achieved.

[0148] Once all hydrofoil shapes are optimized and work in harmony with each other, the potential energy extraction or electrical output is calculated. Here is an example result of the analysis of a particular blade shape developed during the early design phase, using CFD to analyze the pressure differential between the two sides of the rotor blades (intrados and extrados) as they rotate through the water (to determine the best shape and number of blades). Reference is made here to Figures 39 and 40, which illustrate the respective high pressure zone on the top of the hydrofoil (extrados) (90) and low pressure zone on the top of the hydrofoil (intrados) (92) on both sides of the rotor blades.

[0149] It will be appreciated that there are elements of trial and error involved not only in the first stage, but also to some degree in the second stage of the process. In the first stage, trial and error is informed not only by the skill of the craftsman applying the principles taught in this application, but also by an intuitive application of general fluid dynamics principles and, more importantly, by the quantitative test results provided by the various types of software that are applied to verify the effects of each modification made to the individual component designs. In the second stage, where testing is done in 3 dimensions and for combinations of components, there are many opportunities for changes that can be made; however, optimization is relatively straightforward at this point. From CFD analysis, areas that evidence a lack of laminar flow and/or turbulence can be detected and modified to remove these undesirable flow effects. Typically, a target is considered which, theoretically, is believed to be the best possible improvement in results, for example, an increase in the flow velocity through the turbine of about three times the ambient inlet stream velocity. Alternatively, a target of a certain improvement in turbine power output may be chosen, compared with a known turbine of comparable size. When one or both of these objectives are approached or achieved, optimization is considered to have been achieved. For example, in Figures 34 and 35, the essential dimensions are shown for a preferred embodiment of a turbine according to the invention, i.e. a 1.5 meter diameter turbine that has been optimized for use in a current with a velocity in the region of 3 knots, as shown in the captions that follow. Caption for Figures 13 and 34 Caption for Figure 34 Caption for Figure 35

[0150] Afterwards, the structural aspects of the design shape are analyzed in a finite element analysis program, such as the so-called CD-Adapco FEA, Scan and Solve or similar. This structural engineering is to confirm that the profile shapes that have been determined can actually be constructed with the required strength, for example with composite materials. There are also several other software programs that can also be used along the way, such as Sol id Works, AutoCAD with simulation of mechanical events, but they are minor contributors to the design.

[0151] Once the turbine shapes are determined by intuitive design/sketching, 3-D modeling shape optimization, and CFD analysis, Stage III of development begins. This stage is the physical construction of a fully functional prototype and testing under real-world conditions while monitoring and documenting all design parameters. This involves recording the rotor section rpm, the turbine unit electrical power, and video recording of the flow characteristics through tufting of all surfaces (similar to an airplane wing in a wind tunnel). These tests are performed at a variety of different flow velocities from 1 knot to 6 knots using various configurations of throttle casing shapes, annular diffuser shapes, and rotor section shapes. Ultimately, this testing results in final confirmation of the functionality and efficiency of the design at a given flow velocity and turbine size.

Site-specific design

[0152] Additionally, this unique design methodology can be utilized to improve the extraction of maximum power from any naturally occurring stream by site-specific design. The first step of site-specific design is to collect flow data from features at a specific site or location. Flow velocities, flow direction, flow mass characteristics (volume of water flowing at any given time), and fluctuations in flow over a given period of time will be accurately measured and recorded using acoustic Doppler equipment. The second step is to assess, record, and document the types and quantities of marine and wildlife in the area selected for the installation site by extended video recording, diving, and recording of all species and sizes of marine animals. It is also necessary to record the type and quantity of debris floating in the water. After this, the design methodology outlined above can begin and firstly, a turbine optimized for a specific location can be developed by first adjusting the hydrofoil shape of the accelerator casing, the diffuser, the central hub and the rotor blades and then adjusting the bar spacing on the wildlife and debris remover to the local requirements. This will ensure that the turbine does not harm wildlife, that the turbine is not hindered by floating debris and that the maximum amount of energy/electricity can be extracted at the precise location.

[0153] All computer programs that were mentioned in the previous description of the methodology of the present invention are available on the market and their modes of use are also well known to those skilled in the art.

[0154] Thus, the applicant has conceived certain innovative designs for hydrokinetic turbines and, further, has taken concepts, tools and information from several different fields and employed and/or combined them in innovative ways to design unidirectional hydrokinetic turbines that exhibit significantly greater efficiency. This is due in large part to the synergistic interaction of multiple, innovative turbine components that incorporate novel asymmetric hydrofoil features, which have been novelly optimized for the specific environment in which they are to be employed. The "novelty of design process" is evident because never before have engineers and designers been able to obtain highly efficient results as demonstrated with respect to the hydrokinetic turbines according to this invention. With these efficiencies, the turbines of the invention can be usefully employed in many contexts where the current velocity is too low to permit the use of prior art turbines.

[0155] The design of these hydrokinetic turbines and components are unique in that no other design to date has combined all of the possible hydrodynamic advantages, allowing for new combinations (in component selection, component design, and interaction of these components together) to optimize turbine power and accelerate water flow to extract the most energy possible with the turbines of the present invention. Although the hydrodynamic principles are well known, the use of these principles and the combination of innovative designs and the effects of all of the different elements utilized in this design, especially the mutually beneficial and synergistic effects of these combined elements, are novel and inventive. As demonstrated in this design, each element was initially designed and then optimized for the flow velocity and turbine size, and thus the end result is a hydrokinetic turbine with far greater power and efficiency than other designs proven to date. Parts List 10 Front Wildlife and Debris Remover 12 Front O-ring for attaching deflector rods 14 Hydrofoil-shaped deflector rods 15 Distance between deflector rods 16 Rear/back ring of remover for attaching deflector rods 18 Rear/back Wildlife and Debris Removers 20 Complete Throttle Housing 21 Hydrofoil-shaped S-shaped/double-curve Throttle Cross-section 22 Throttle Housing Front/Inlet Duct Housing 23 Throttle Housing Center Section/Stator Housing 24 Hydrofoil-shaped Throttle Housing Cross-section without S-shaped 25 Stator Metal Windings 26 9 Bearings/Ball Bearings (3 Front Thrust Bearings, 3 Rear Thrust Bearings, and 3 Alignment Bearings) 28 rear housing/rear section of accelerator housing 29 feathered edge of accelerator housing 30 complete main rotor section with hydrofoil-shaped blades, rotor blade housing with a recess for installation of a permanent magnet and a hydrofoil-shaped central hub 32 permanent magnet rings mounted in the recess of the rotor section 33 rotor blade tip 34 hydrofoil-shaped rotor blades 35 hydrofoil-shaped cross-sections of rotor blades 36 hydrofoil-shaped central hub 37 open center of main rotor section 38 rotor blade housing with recess for installation of permanent magnet 39 rotor blade base 40 annular diffuser with hydrofoil-shaped cross-section 42 second annular diffuser 44 third annular diffuser 50 tubular support structure for various mounting purposes 51 profile-shaped fixing rods hydrofoil between turbine components and support structure 52 support pile for rotation 53 waterproof plug for removal, rings and brushes for rotation inside the pile 54 floating raft or ocean barge 55 support structure for rotation on a raft/barge installation 56 cranes for rotation of the turbine on the raft/barge installation 58 submersible raft for floating installation 59 moorings or screw type anchorage 60 turbine tail rudder for steering the turbine in the direction of water flow 62 winglets attached to the turbine for towing installation 64 attached strap and anchorage for vessel/raft-mounted installation or for floating installation 66 bearing strap for submerging the turbine by shortening or lengthening it for lifting 72 incidence/angle of attack of the hydrofoil blade 74 hydrofoil cable/cable length 75 rotor blade length 76 section thickness hydrofoil cross section/shape78 rotor blade twist/incidence change80 solid/bulbous center hub82 hydrofoil-shaped vanes to hold solid center hub in position83 diffuser inlet diameter84 throttle housing inlet diameter85 center hub overall diameter86 center hub profile/cable thickness87 throttle housing length88 diffuser length89 center hub length90 throttle housing profile/cable thickness91 diffuser profile/cable thickness92 center hub outlet diameter93 throttle housing outlet diameter94 diffuser outlet diameter95 flow direction

Claims (14)

1. A unidirectional hydrokinetic turbine having a water inlet end and a water outlet end that define a single direction of water flow through the turbine, comprising: a generally cylindrical throttle guard (20) having a length extending from the water inlet end to the water outlet end and comprising a radially inner wall surface and a radially outer wall surface spaced from the radially inner wall surface, to form a radial wall cross-section, wherein the radially inner wall surface defines within its cylindrical cross-section a water flow area; located within the water flow area an integral hydrokinetic force generating member that rotates as a unit in a single direction in response to water flow in the single direction during generation of force within the throttle guard (20), the integral force generating member comprising: a central hub member (36) having a hydrodynamic profile and an open center (37) surrounded by an inner wall defining a water flow passage; and a plurality of blade members (34) mounted on the hub member (36), each blade member (34) having two edges and extending radially outwardly from a radially inward base end thereof, at which base end each blade (34) is mounted to the central hub member (36) for rotation therewith to form a rotor assembly, the blade members (34) terminating in radially outward blade tips (33); characterized in that: the rotor assembly further comprises an outer rotor ring (38) to which the blade tips (33) are attached and that has an outer circumference that is configured for rotation within the throttle guard (20), and wherein the blade members (34) have a cable length at their radially outward ends that is greater than the cable length at their radially inward ends; and an annular diffuser (40) comprising a generally cylindrical ring member having a wall cross-section comprising an asymmetric hydrofoil shape, the annular diffuser (40) having a diameter larger than the diameter of the throttle guard (20) and being positioned behind the main throttle guard (20), in the direction of water flow through the turbine. 2. Unidirectional hydrokinetic turbine according to claim 1, characterized in that the central hub member (36) comprises a generally round profile member and in which the wall members around the open center (37) form an asymmetric hydrodynamic profile, with the extrados being directed outwards from the turbine and the intrados facing towards the center of the hub. 3. Unidirectional hydrokinetic turbine according to claim 1 or 2, characterized in that the blades (34) have an asymmetric hydrofoil-shaped cross-sectional configuration. 4. Unidirectional hydrokinetic turbine according to claim 1 or 2, characterized in that it comprises a magnet mounted on the outer ring of the rotor (38) for rotation with the rotor assembly. 5. Unidirectional hydrokinetic turbine according to claim 1, 2, 3 or 4, characterized in that the blade members (34) have a profile thickness at their radially outer ends that is greater than the profile thickness at their radially inner ends. 6. Unidirectional hydrokinetic turbine according to claim 2, characterized in that the central hub (36) has a length that extends both forward and rearward a substantial distance beyond the edges of the blade members (34). 7. Unidirectional hydrokinetic turbine according to claim 6, characterized in that the central hub (36) extends from the blade shoulders (34) forward to a first point that is behind the water inlet end of the throttle guard (20), and extends rearward to a point as far as the water outlet end of the throttle guard (20). 8. Unidirectional hydrokinetic turbine according to claim 7, characterized in that the inner hub (36) extends for a total distance of approximately 2/3 of the length of the accelerator guard (20). 9. Unidirectional hydrokinetic turbine, according to claim 1, characterized by the fact that the annular diffuser (40) is positioned behind the throttle guard (20), in the direction of water flow through the turbine, in an overlapping relationship. 10. Unidirectional hydrokinetic turbine according to claim 1, 2 or 3, characterized in that the cross-section of the wall of the generally cylindrical throttle guard (20) has an asymmetric hydrofoil shape, the hydrofoil shape serving to accelerate the flow of water through the throttle guard (20) and to create a negative pressure field behind the throttle guard (20), in the direction of the water flow. 11. Unidirectional hydrokinetic turbine according to claim 10, characterized in that the annular diffuser (40) has a diameter larger than the diameter of the throttle guard (20) and is positioned behind the main throttle guard (20) in the direction of water flow through the turbine, wherein the hydrofoil shape of the annular diffuser (40) serves to accelerate the water flow through the annular diffuser (40) and to create a negative pressure field behind the annular diffuser (40), and in cooperation with the hydrofoil of the throttle guard (20), the rotor hub and/or the blades (34) thus serve to increase the acceleration of the water flow through the main throttle guard (20) at the location of the rotor assembly. 12. Unidirectional hydrokinetic turbine according to claim 11, characterized in that the throttle guard has a forward portion upstream of the blades (34) and a rear portion downstream of the blades (34), and in which the asymmetric hydrofoil shape comprises a profile in which the radially outer surface comprises a convex forward portion and a concave rear portion, and the radially inner surface comprises a convex rear portion and a forward portion, measured from the blades (34) to the water inlet end, that has a shape that is straight or curved, and in which the water flow area within the throttle guard is free of fixed structure. 13. A method for designing a unidirectional hydrokinetic turbine having a water inlet end and a water outlet end that defines a direction of water flow through the turbine, comprising: selecting a generally cylindrical throttle guard (20) having a wall cross-section comprising an initial asymmetric hydrofoil shape and defining within its cylindrical cross-section a flow area, wherein the hydrofoil shape is selected based on fluid dynamics principles that serves to accelerate the flow of water through the throttle guard (20) and to create a negative pressure field behind the throttle guard (20) in the direction of water flow; designing a rotor assembly that is mounted for rotation within the throttle guard (20) about an axis that is generally parallel to the direction of water flow through the turbine, the rotor assembly comprising (i) a generally elongated cylindrical central hub (36) having an open center (37) and a wall cross-section comprising an initial asymmetric hydrofoil shape; (ii) a plurality of rotor blades (34) attached to and extending radially outwardly from the wall of the central hub (36) for rotation therewith and terminating at rotor tips, which blades (34) have an initial asymmetric hydrofoil-shaped cross-sectional configuration that is selected based on fluid dynamics principles and also includes a cable length at their radially outer ends that is greater than the cable length at their radially inner ends; and(iii) an outer rotor ring to which the blade tips (33) are attached and having an outer circumference that is configured for rotation within the throttle guard (20); designing an annular diffuser (40) comprising a generally cylindrical ring member having a wall cross-section comprising an initial asymmetric hydrofoil shape that is selected based on fluid dynamics principles, wherein the annular diffuser (40) has a diameter larger than the diameter of the throttle guard (20) and is configured to be positioned behind the main throttle guard (20), in the direction of water flow through the turbine; and modify the initial hydrofoil shapes of the throttle guard (20), the central hub (36), the rotor blades (34) and the annular diffuser (40), in response to CFD testing of a turbine design comprising these components, so as to provide final hydrofoil shapes for all of these components that (a) improve the ability to accelerate the water flow through the annular diffuser (40) and create a negative pressure field behind the annular diffuser (40), and (b) provide cooperation between the final hydrofoil shapes of the throttle guard (20), the rotor hub (36) and the blades (34) to increase the acceleration of the water flow through the throttle guard (20) at the location of the rotor assembly. 14. A method for designing a unidirectional hydrokinetic turbine as defined in any one of claims 1 to 12, wherein the annular diffuser (40) is configured to be positioned behind the main throttle guard (20), in the direction of water flow through the turbine, in an overlapping relationship and wherein the throttle guard (20) has a forward portion upstream of the blades (34) and a rear portion downstream of the blades (34), and wherein the initially selected asymmetric hydrofoil shape of the throttle guard comprises a profile in which the radially outer surface comprises a forward convex portion and a rear concave portion, and the radially inner surface comprises a rear convex portion and a forward portion, measured from the blades (34) to the water inlet end, that has a shape that is straight or curved.