Patent Application
20120306205
The present invention relates generally to turbine assemblies useful for harnessing hydroelectric energy. More particularly, the present invention relates to improved fluid flow past turbine assemblies that provide increased efficiency and power output at a given flow rate.
Hydroelectric energy refers to the generation of energy from a flow current or velocity of water. This type of energy is different from hydroenergy, which traditionally refers to power generated using dams (impoundment or run-of-river). Because hydroelectric energy relies on the velocity of water, these energy systems can be placed into sources of flowing water with minimal infrastructure or environmental impacts. As a result, hydroelectric power is considered cutting-edge waterpower.
When assembled and driven by fluid flow through conduit 118, turbine assembly 128 rotates with a shaft to which it is coupled, and, when connected to a power generator (not shown to facilitate illustration and discussion), produces electric power that can be stored, consumed, or fed into a power grid. A portion of the fluid flow through conduit 118, however, does not drive rotation of turbine assembly 128, but rather, flows through bypass area 120, which is located between the outer periphery of the blade-swept area of turbine assembly 128 (including the region above and below the turbine assembly) and the inner surface of conduit 118.
Unfortunately, the conventional in-conduit turbine assembly suffers from drawbacks. By way of example, bypass area 120 allows a certain amount of fluid to flow around the turbine instead of through it, causing a decrease in power output at a given flow rate. As another example, frequently there are drag loses due to the exposure of the surface of mounts 116 and other locations e.g., where blades 114 mount to hub plate 122. This drawback is exacerbated particularly when a saw-tooth design of mounts 116 is employed. As a result, bypass area 120 in conventional in-conduit turbine designs provides a path for fluid to flow past certain features of the turbine assembly, e.g., where blades 114 mount to saw-tooth mounts 116, causing an increase in drag of fluid flow, and consequently, a decrease in efficiency of the turbine.
What is therefore needed are improved systems and methods of assembling turbine assemblies that do not suffer from the drawbacks encountered by their counterpart conventional designs.
In view of the foregoing, in one aspect, the present invention provides novel systems and methods for increasing efficiency and power output of in-conduit hydroelectric power systems and turbines.
In one aspect, the present invention discloses a turbine. The turbine includes: (1) a central longitudinal shaft configured to mount and to rotate on a central axis perpendicular to a direction of fluid flow; (2) a plurality of arcing blades coupled with the shaft, with the blades extending radially outwardly from the shaft, and the blades including an airfoil cross-section along a substantial length of the blades; and (3) a hydrodynamic cap covering a location where the arcing blades couple with the shaft such that in an operating state of the turbine, the presence of the hydrodynamic cap reduces an amount of bypass area, which is an area outside a region that is swept by the arcing blades. Preferably, the hydrodynamic cap forces a larger amount of liquid to flow through the region that is swept by the arcing blades than if the hydrodynamic cap was absent.
In one embodiment of the present invention, the blades are evenly spaced around said shaft. Preferably, the angle between the plane defined by each of the blades and the central axis of the shaft is between about 10° and about 45°.
In certain embodiments of the present invention, the hydrodynamic cap is disposed above the location where the arcing blades couple with the shaft. In alternate embodiments, the hydrodynamic cap is disposed below the location where the arcing blades couple with the shaft. Preferably, the turbine includes opposing hub assemblies, each including a hub plate and a plurality of mounting brackets for securely coupling opposite ends of the plurality of blades to the shaft. In such embodiments, the turbine includes two opposing hydrodynamic caps, each covering one of the hub assemblies.
In preferred embodiments of the present invention, the hydrodynamic cap is made from at least one material selected from a group consisting of plastic, metal, composite material and alloy. The composite material may include resin-impregnated fiberglass or resin-impregnated fiber. In certain embodiments, the inner surface of the hydrodynamic cap has a radius of curvature that is substantially equal to the radius of curvature of the turbine. Preferably, the hydrodynamic cap has an angular distance that is between about 25° and about 60°, wherein an equator of the turbine is at an angular distance of 90°. The poles, which are located at an outermost location of the turbine that is perpendicular to the equator, have an angular distance of 0°. In preferred embodiments of the present invention, the hydrodynamic cap has an aperture defined therein to allow the shaft to pass through the aperture of the hydrodynamic cap, and the aperture is at a location that is perpendicular to the equator of the turbine.
In another aspect, the present invention discloses a turbine. The turbine includes: (1) a central longitudinal shaft configured to mount and to rotate on a central axis perpendicular to a direction of fluid flow; (2) a plurality of arcing blades coupled with the shaft, the blades extending radially outwardly from the shaft, and the blades including an airfoil cross-section along a substantial length of the blades; and (3) wherein the turbine has a diameter that scales with an inner diameter of a conduit, inside which the turbine is installed for generating power, such that a clearance created between the inner sidewall of the conduit and an outermost surface of the turbine, when the turbine is installed in the conduit, ranges from about 0.5% to about 2% of the outermost diameter of the turbine. Preferably, the clearance between the inner sidewall of the conduit and the outermost surface of the turbine is between about 0.5% and 1% of the outermost diameter of the turbine.
In yet another aspect, the present system discloses a power generating system that generates power from the movement of fluids. The system includes: (1) a turbine, which includes: (a) a central longitudinal shaft configured to mount and to rotate on a central axis perpendicular to a direction of fluid flow; (b) a plurality of arcing blades coupled with the shaft, the blades extending radially outwardly from the shaft, and the blades including an airfoil cross-section along a substantial length of the blades; and (c) a hydrodynamic cap covering a location where the arcing blades couple with the shaft such that in an operating state of the turbine, presence of the hydrodynamic cap forces a larger amount of liquid to flow through a region that is swept by the arcing blades of the turbine than if the hydrodynamic cap was absent; and (2) a generator operatively coupled with the shaft such that when fluid flows through the turbine, the blades and the shaft rotate around the central axis causing the generator to produce electricity. Preferably, the generator provides an increase in power efficiency that is less than or equal to about 30% in the presence of the hydrodynamic cap, as opposed to when the hydrodynamic cap is absent.
In yet another aspect, the present invention discloses a process for manufacturing a power generating system customized for an application. The process includes: (1) obtaining a power requirement for the application; (2) determining dimensions of a turbine and a hydrodynamic cap that are capable of providing the power requirement for the application; (3) coupling a plurality of blades and a shaft to form a turbine having these dimensions; (4) installing the turbine system in a conduit; and (5) operatively coupling a generator subassembly to the turbine system and producing the power generating system. Preferably, determining includes referring to a lookup table, which contains various predetermined values for dimensions of the turbine and for the hydrodynamic cap that correspond to certain predetermined power requirements.
In preferred embodiments of the present invention, the process for manufacturing a power generating system customized for an application includes the further steps of: (1) obtaining a hydrodynamic cap of these dimensions; and (2) assembling the hydrodynamic cap and the turbine to form a turbine system.
In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention. It will be apparent, however, to one skilled in the art that the present invention is practiced without limitation to some or all of these specific details. In other instances, well-known process steps have not been described in detail in order to not unnecessarily obscure the invention.
Turbine assembly 228 includes arced turbine blades 214, which are attached to a hub plate via mounts, which are not shown to facilitate illustration and discussion. During turbine operation, arcing blades 214 rotate, preferably sweeping a substantially spherical shape, around a central longitudinal shaft (not shown to facilitate illustration and discussion), which is disposed perpendicular to a direction of fluid flow through conduit 218. Turbine assembly 228 of
Hydrodynamic caps 224 and 226 are attached to a first end and a second end, respectively, of turbine assembly 228. As will be explained later in reference to
The presence of hydrodynamic caps 224 and 226 of the present invention forces a larger amount of fluid, for a given or fixed fluid flow rate through a conduit, to flow through turbine assembly 228 or a region that is swept by blades 214 than would if the hydrodynamic caps were absent, and consequently, a lesser amount of fluid flows through bypass area 220. Stated another way, the presence of hydrodynamic caps 224 and 226 forces a larger amount of fluid to flow through the centerline plane of conduit 218 or through the centerline plane of blade-swept area of turbine assembly 228 than if the hydrodynamic caps were absent. Furthermore, those skilled in the art will recognize that for a given or fixed fluid flow rate through a conduit, the presence of hydrodynamic caps provides for a greater average fluid velocity through turbine assembly 224 and 226, or, in the alternate, through the centerline plane of turbine assembly 228.
Those skilled in the art will recognize that a single hydrodynamic cap may be uses in a turbine assembly design of the present invention to reduce the bypass area, but that use of two hydrodynamic caps represents a preferred embodiment of the present invention.
Regardless of whether one or two hydrodynamic caps are used, forcing more water through the area swept by blades 214 translates into higher power generation from the turbine assemblies of the present invention. In those instances, where the average fluid velocity through the centerline of the turbine assembly is being monitored, the increase in power output can be thought to coincide with an increase in “tip speed ratio.” Tip speed ratio refers to the ratio of the speed of the blade (e.g., blades 214 of
In addition to increasing power output and efficiencies by forcing a larger amount of fluid through the operating turbine assemblies, hydrodynamic caps 224 and 226 realize the same advantages of increased power output and efficiency by reducing drag loses. Specifically, hydrodynamic caps 224 and 226 conceal protruding features (e.g., presence of saw-tooth mounts 116 and/or connection points of blades 114 and hub plate 122 of
Bottom end of blades 314, lower saw-tooth mounts 346, bolts 352, lower hub plate 330, lower hydrodynamic cap 324, bolts 342, lower split shaft coupler 334, and bolts 338 are substantially similar to and are present in substantially the same configuration as their counterparts in the upper portion of the inventive turbine assembly shown in
Turbine assembly 328 has blades 314 spaced, preferably evenly, around a shaft. In preferred embodiments of the present invention, the angle between the plane defined by each of blades 314 and the central axis of a shaft is between about 10° and about 45°. In certain embodiments, blades 314 extend such that a plane defined by them is not parallel to a shaft. Preferably, blades 314 extend radially outwardly from a shaft, with the blades having an airfoil cross-section along a substantial length of the blades.
While
Preferably, hydrodynamic caps 324 and 326 are made from a rigid, waterproof material, which includes at least one material selected from a group consisting of metal, plastic, composite material and alloy. The composite material may include resin-impregnated fiberglass or resin-impregnated fiber. In preferred embodiments of the present invention, the hydrodynamic cap has an aperture defined therein to allow a shaft to pass therethrough at a location that is perpendicular to a centerline plane of the inventive turbine assemblies.
Other components of turbine assembly 328, such as hub plates 322 and 330 and their respective saw-tooth mounts, upper and lower split shaft couplers 332 and 334 and the various bolts connections, are made from any rigid material. In preferred embodiments of the present invention, however, they too are made from the waterproof materials described above in connection with the hydrodynamic caps.
In alternate embodiments, turbine assemblies of the present invention include one or more mounting brackets for securely coupling opposite ends of blades to a shaft. In other embodiments of the present invention, hub plates do not include saw-tooth mounts to facilitate a connection between the hub plate and the blades. In these embodiments, fastening techniques or designs well known to those skilled in the art are used.
It is important to note that although the dome shape of the hydrodynamic cap provides the advantages of higher power output and efficiency, it may also cause undesired head loss during fluid flow. If the hydrodynamic cap is designed too large, such that a significant portion of an end of the turbine assembly is covered to reduce the bypass area, a significant increase in fluid flow rate through the turbine is realized at the expense of undesired head loses in fluid flow through a conduit. Conversely, if a hydrodynamic cap is designed too small, such that a significant portion of an end of the turbine assembly is uncovered (exposing a large bypass area for fluid flow), a reduction in head loss is realized at the expense of lower power output and efficiency for the operating turbine. As a result, the present invention recognizes that when selecting appropriate dimensions for the hydrodynamic cap, it is important to strike a balance between dimensions that provide an increased power output and efficiency, and dimensions that do not unduly adversely impact head loss of fluid flow through the conduit. To this end, hydrodynamic caps of varying sizes may be used in the inventive in-conduit applications of the present invention. An angular distance of hydrodynamic cap along a blade-swept area is a value between about 25° and about 60°, preferably between about 30° and about 50°, and more preferably a value of about 40°.
In this embodiment, blade-swept area of turbine assembly 528 is large enough to reduce the bypass area of fluid flow encountered in conventional turbine designs. In other words, in this embodiment, relatively large diameter of a blade-swept area of the inventive turbine assemblies scales with inner diameter of conduit 518. A clearance created between the blade-swept area of the turbine assembly and an inner surface of a conduit is a value that is between about 0.5% and about 2% of the blade-swept area of the turbine assembly, and preferably between about 0.5% and about 1% of the blade-swept area of the turbine assembly.
Although the embodiment shown in
A generator assembly 660 is disposed atop turbine assembly 628 as shown in
As shown in
In certain embodiments, with reference to the above-described systems, the present invention provides a process for manufacturing a power generating system customized for an application. To that end, a first step involves obtaining a power requirement for the application. A next step includes determining the dimensions of a turbine and, preferably, a hydrodynamic cap if one or more are to be used to reduce the bypass area. The turbine and/or hydrodynamic cap are sized to meet the power requirements for the application. Preferably, determining the turbine and/or hydrodynamic cap dimensions is carried out by referring to a lookup table that correlates values for the dimensions of the turbine and/or hydrodynamic cap to values of power requirements.
Having established the dimensions of a turbine and/or hydrodynamic cap, the assembly processes of the present invention preferably proceeds to steps that involve assembling the various turbine components. A plurality of blades and a shaft are coupled to provide the dimensions necessary for the power requirement of the application. Next, a step of installing the turbine system inside a conduit is carried out. Finally, a generator subassembly is operatively coupled to the turbine system to form a power generating system customized for a specific application.
In those embodiments where it is necessary to use a hydrodynamic cap, processes of the present invention further include obtaining one or more hydrodynamic caps and incorporating one or more hydrodynamic caps into the turbine assembly design as shown in
Although illustrative embodiments of this invention have been shown and described, other modifications, changes, and substitutions are intended. Accordingly, it is appropriate that the appended claims be construed broadly and in a manner consistent with the scope of the disclosure, as set forth in the following claims.
The application claims priority from U.S. Provisional Application having Serial No. 61,493,937, filed on Jun. 6, 2011, which is incorporated herein by reference for all purposes.
| Number | Date | Country | |
|---|---|---|---|
| 61493937 | Jun 2011 | US |
