Patent Application
20090297347
The present invention relates generally to electric power generation, and more particularly to a turbine configured to convert the bulk motions of wind, water, or other moving fluids into electricity. Although the invention has wide utility for wind and hydroelectric power generation, it may be particularly suitable for use in rivers and other bodies of water having relatively stable water currents.
Electric power may be generated by a number of methods, including burning fossil fuels such as coal, petroleum or natural gas, through the nuclear decay of heavy elements, from solar energy, from wind energy, and from the energy of moving water, which is also known as hydroelectric power generation. In each case, the harnessed energy is used to rotate a coil of conducting wire relative to a magnet, which produces an electric current in accordance with well-known principles of electromagnetism.
Although coal burning accounts for around half of the electric power generated in the United States each year, producing energy in this manner is unsustainable due to finite coal resources, and also produces undesirable environmental effects. As a result, other methods of power generation may become increasingly important. In particular, hydroelectric power generation currently accounts for roughly eight to ten percent of the power generated in the United States each year, and worldwide, hydroelectric methods supply roughly one fourth of the world's electricity. In countries such as Norway, Zaire and Brazil, almost all electricity is generated hydroelectrically. Although wind power currently only accounts for around one percent of worldwide power generation, this method may become increasingly important as supplies of finite burnable resources dwindle and environmental concerns mount.
Most conventional hydroelectric power generation involves the use of large power generators placed inside or at the base of dams. This is because the amount of power generated by a conventional hydroelectric generating station is roughly proportional to the distance, or “head,” between the upper water level and the turbine driven by the falling water. However, the use of dams affects those who live both upstream and downstream from the dam, and also may drastically modify the local habitats of plants and animals. For example, many large dams in the Columbia River Basin impede the migration of Pacific salmon, which may be leading to the extinction or near-extinction of some species. For this and other reasons, generation of hydroelectric power by methods that do not require dams or reservoirs is desirable.
In addition, most conventional wind generation devices use horizontal axis turbines, in which the turbine blades are oriented into the wind and spin approximately vertically. While this has the advantage that the blades are always facing the wind and generating torque, it also has several disadvantages, including the need for separate wind direction sensing equipment, the complication of rotating the turbine into the wind as the wind changes directions, the creation of vertically directed turbulence that may harm birds and other wildlife, and a large vertical profile that may be more dangerous to flying creatures and aesthetically unappealing. Furthermore, the speed at the tips of the blades in a horizontal axis wind turbine typically exceeds the wind speed, which can further endanger bird life and which has given rise to the nickname “bird blender” for these devices.
For these and other reasons, turbines with vertical axes and horizontal blades may be desirable, particularly if they can be constructed so that the force of the fluid provides the turbine with a relatively large net torque.
The present disclosure relates to a fluid-driven turbine for power generation. Turbines according to this disclosure are provided with a central shaft that is rotatable about a central axis, and a plurality of vanes or vane assemblies mounted on the central shaft and configured to undergo rotational motion around the central axis of the shaft, to rotate the shaft. The rotating shaft may be attached to a generator, an alternator, a pump, or any other useful device, in much the same way that the rotation of a conventional turbine may be converted into electricity or useful mechanical work.
To provide a net rotational torque, vanes having a component of motion in the direction of a fluid current (i.e., moving with the current) may be configured to present a relatively large resistive surface area to the moving fluid, whereas vanes having a component of motion opposite the direction of the fluid current (i.e., moving against the current) may be configured to present a relatively small resistive surface area to the moving fluid. Pairs of vanes or vane assemblies located on opposite sides of the central shaft may be configured to open and close in coordinated motion, to present the appropriate surface area to the current on each side of the central shaft in a synchronized manner.
Referring to the embodiment shown in
Turbine 10 is shown connected to an ancillary generator 12 via a gear 14. However, the present disclosure is not to be limited to the connection of turbine 10 to this particular device. Connections to other devices and/or mechanisms configured to receive rotational motion, such as, for example, an alternator or a pump, are also within the scope of this disclosure.
Each individual vane assembly 50 of each adjacent pair 40 of vane assemblies may include a support rod 52 rotatable about an axis transverse to central axis 22, and a first vane 60 having a capture surface 62 and being fixedly attached to support rod 52 so that rotation of first vane 60 about axis 22 causes support rod 52 to correspondingly rotate about axis 22, and vice versa.
Each vane assembly 50 also may include a second vane 70 having a capture surface 72 and being fixedly attached to support rod 52 diametrically opposite central shaft 20 from first vane 60 so that rotation of second vane 70 about axis 22 causes support rod 52 to correspondingly rotate about axis 22, and vice versa.
In some embodiments, second vane 70 may be mounted on support rod 52 transversely or even perpendicularly relative to first vane 60, as will be discussed further below. Although for each vane assembly 50, first vane 60 and second vane 70 are separately labeled, first vane 60 and second vane 70 may be identical (although this is not required). Accordingly, the more general reference of “vanes (60, 70)” occasionally will be used below to refer generally to first vanes 60 and second vanes 70.
Each adjacent pair 40 of vane assemblies may be mounted on central shaft 20 in various ways. In some embodiments, each adjacent pair 40 of vane assemblies may include a mounting rod 42 fixedly attached to central shaft 20, the mounting rod 42 supporting the support rods 52 and allowing them to rotate about axis 22. Each adjacent pair 40 of vane assemblies may additionally or alternatively include one or more connecting portions 44 for supporting the two support rods 52 together and/or with mounting rod 42.
Each vane (60, 70) may be rotated relative to the axis of its respective support rod (see
When turbine 10 is submerged in a fluid current 16 (see
In some embodiments, such as the one shown in
For each adjacent pair 40 of vane assemblies, second vane 70 on one vane assembly 50 may be adjacent to second vane 70 on the other vane assembly 50, so that fluid 16 current causes them to open and close (see the bottom three vanes in
More generally, in some embodiments, for each pair 40 of adjacent vane assemblies, capture surface 62 of first vane 60 on a first vane assembly 50 may at least partially face capture surface 62 of first vane 60 on a second vane assembly 50 when the support rod 52 on each vane assembly is in a closed position (i.e., moving against fluid current 16). Likewise, for each adjacent pair 40 of vane assemblies, capture surface 72 of second vane 70 on a first vane assembly 50 may at least partially face capture surface 72 of second vane 70 on a second vane assembly 50 when the support rods 52 on each vane assembly are in a closed position.
Referring now to
In
The force asserted on capture surface 62 of first vane 60 causes first vane 60 to rotate towards the open position, causing support rod 52 to correspondingly rotate. This rotation of support rod 52 simultaneously rotates second vane 70 toward its closed position. Likewise, the force asserted on the surface opposite capture surface 72 of second vane 70 causes first vane 70 to rotate towards the closed position, causing support rod 52 to correspondingly rotate. This rotation of support rod 52 simultaneously rotates first vane 60 toward its open position. Accordingly, it should be understood that rotation of either first vane 60 or second vane 70 assists in the rotation of the other, and vice versa. Thus, at any given time, pairs of vanes disposed opposite each other relative to the central shaft will be rotationally offset relative to the axes of their respective support rods, typically by an amount near 90 degrees, but in general by any desired amount. This offset ensures that when one vane is open, its counterpart on the other side of the central shaft will be closed, and vice versa.
In
In
In
While many embodiments will be configured for submersion into liquid currents (e.g., a river) to generate hydroelectric power, it should be understood that other currents created by other moving fluids, such as air, may also be harnessed by embodiments of this disclosure.
In some embodiments, adjacent vanes (60, 70) may open up to a maximum angle, labeled θ in
Vanes (60, 70) may be prevented from opening further than θ by various mechanisms. In some embodiments, seen best in
More specifically, each first vane 60 may be attached to support rod 52 at a position adjacent to a first edge 68 of first vane 60 so that first edge 68 forms part of blocking portion 66. The blocking portion 66/first edge 68 on first vane 60 on one vane assembly 50 of each adjacent pair 40 of vane assemblies may be configured to abut the blocking portion 66/first edge 68 on first vane 60 on the other vane assembly 50 of each adjacent pair 40 of vane assemblies when first vanes 60 open (i.e., when fluid current 16 pushes against their capture surfaces) to prevent first vanes 60 from opening further than θ. In other words, edges 68 of adjacent vanes 60 may interfere with each other and prevent further motion, once the angle between the vanes reaches a desired maximum. Second vanes 70 may also include similar blocking portions (not shown) as first vanes 60.
As noted above, second vane 70 may be mounted on support rod 52 transversely or even perpendicularly relative to first vane 60. Accordingly, each support rod 52 may be rotatable between a first position where capture surface 62 of first vane 60 defines a first resistance area 64 (see
In some embodiments, the second and third resistance areas may be substantially equal. Likewise, in some embodiments, the first and fourth resistance areas may be substantially equal. Equalizing the resistance areas in this manner ensures that the rotation of turbine 10 about first axis 22 remains constant in a constant fluid current 16.
While the vanes (60, 70) are shown generally being substantially planar, it should be understood that the vanes (60, 70) may take other shapes. For example, vanes (60, 70) may have capture surfaces (62, 72) that are at least partially concave.
Support rods 52 may be various lengths. In one embodiment, support rods 52 are at least about three feet in length. Greater lengths are possible, and may only be limited by the space available in fluid current 16 (e.g., depth and width of a river). Because the torque produced by each vane around the central shaft is directly proportional to the length of the corresponding support rod, relatively large turbine assemblies may be desirable.
As mentioned previously, in some embodiments, each adjacent pair 40 of vane assemblies includes a motion translation mechanism 80 configured to ensure that rotation of the support rod 52 on one vane assembly 50 in each adjacent pair 40 of vane assemblies causes the support rod 52 on the other vane assembly 50 in each adjacent pair 40 of vane assemblies to rotate in an opposite direction.
In the embodiments shown in
In an alternative embodiment shown in
In some embodiments, such as the one shown in
In such embodiments, each support rod 52 may be rotatable between two positions. In a first position, for each adjacent pair 40 of vane assemblies, the capture surface of third vane 90 on one of the vane assemblies defines a first resistance area and the capture surface of fourth vane 100 on the other one of the vane assemblies defines a second resistance area smaller than the first resistance area. In a second position, for each adjacent pair 40 of vane assemblies, the capture surface of vane 90 may define a third resistance area and the capture surface of vane 100 may define an fourth resistance area larger than the third resistance area. In other words, both of vanes 90, 100 are capable of moving between a maximally fluid resistive position and a minimally fluid resistive position.
Furthermore, as was the case with previously described embodiments, each adjacent pair 40 of vane assemblies may include a motion translation mechanism 80 similar to that described above, to synchronize the opening and closing motions of vanes located on opposed sides of the central shaft.
While the present description has been provided with reference to the foregoing embodiments, those skilled in the art will understand that many variations may be made therein without departing from the spirit and scope defined in the following claims. The description should be understood to include all novel and non-obvious combinations of elements described herein, and claims may be presented in this or a later application to any novel and non-obvious combination of these elements. The foregoing embodiments are illustrative, and no single feature or element is essential to all possible combinations that may be claimed in this or a later application. Where the claims recite “a” or “a first” element or the equivalent thereof, such claims should be understood to include incorporation of one or more such elements, neither requiring, nor excluding, two or more such elements.
