Abstract:
A generally spherical turbine configured to rotate transversely within a cylindrical pipe under the power of fluid flowing either direction therethrough is operatively coupled with a rotating machine or generator to produce electricity. In one embodiment, the blades of the spherical turbine curve in an approximately 180 degree arc in a plane that is at an inclined angle relative to the rotational axis of a central shaft. In another embodiment, a deflector is provided upstream of the spherical turbine and within the cylindrical pipe to control flow through the spherical turbine by shielding a part thereof. The blades of the spherical turbine are airfoil in cross section to optimize hydrodynamic flow, to minimize cavitation, and to maximize conversion from axial to rotating energy.

Description:
FIELD OF THE INVENTION 
     The invention relates generally to the field of hydroelectric power generation. More particularly, the invention relates to hydro-electric power generation via fluid flow past a turbine. 
     BACKGROUND OF THE INVENTION 
     U.S. Pat. Nos. 5,451,137; 5,642,984; 6,036,443; 6,155,892; 6,253,700 B1; and 6,293,835 B2 to Gorlov disclose various cylindrical turbines for power systems, the blades of the turbines extending helically to sweep out an open cylinder. The patents disclose mounting such turbines in rectangular and/or square cross-sectional channels or ducts capable of conveying water that rotates the turbines to generate hydro-electric power. Gorlov&#39;s cylindrical turbine has helically curved/twisted blades or vanes mounted to a central shaft by radial struts or spokes of seemingly arbitrary or at least non-airfoil, e.g. circular, cross section. U.S. Pat. No. 5,405,246 to Goldberg discloses a vertical-axis wind turbine with a twisted blade configuration in which two rotatable blades are bent and twisted along their entire lengths to define a body of rotation, with the body of rotation describing “the outer surface of an American football . . . ”. In the only illustrated embodiment of his invention, Goldberg&#39;s blades butt radially against the central rotor at approximately 45 degree angles to imaginary planes at rotational poles normal to his rotor&#39;s axis. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is an isometric exploded assembly drawing of one embodiment of the invention featuring a spherical turbine. 
         FIG. 2  is a front elevation of the assembled embodiment. 
         FIG. 3  is an isometric exploded assembly drawing of the spherical turbine of  FIG. 1 . 
         FIG. 4  is an isometric view of the assembled spherical turbine. 
         FIG. 5  is an isometric view of the assembled spherical turbine in a second embodiment of the invention including an upstream fluid deflector. 
         FIG. 6A  shows a side-sectional view of the pipe of  FIG. 1  including a turbine and circular plate for mounting a proximal end of the turbine&#39;s shaft. 
         FIG. 6B  shows a side-sectional view of the pipe of  FIG. 1  including a turbine and a spherically, concave and circular plate for mounting a proximal end of the turbine&#39;s shaft. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       FIG. 1  is an isometric exploded assembly drawing of a first embodiment of the invented in-pipe hydro-electric power system  10  featuring a spherical turbine. System  10  in accordance with one embodiment of the invention includes a T-section fluid (broadly encompassing a liquid such as water or a gas such as air or the like material exhibiting useful flow characteristics) pipe  12 , a bulkhead or generator assembly  14 , and a spherical turbine assembly  96 . Those of skill in the art will appreciate, by brief reference to  FIG. 2 , that when assembled and driven by fluid flow through pipe  12 , turbine assembly  96  rotates and system  10  produces hydro-electric power that can be stored, consumed, or fed into a power grid. 
     Pipe  12  is generally cylindrical, having a generally circular cross section, although within the spirit and scope of the invention it can be slightly oval in cross section. Pipe  12  typically is a part of a longer and perhaps more complex fluid conveyance or pipe system, and it will be appreciated that an existing pipe system can readily be retrofitted with invented power system  10  by sectioning and replacing the removed section with power system  10 . Thus, pipe  12  is equipped with circular flanges  12   a  and  12   b  for bolting on either end to upstream and downstream pipe ends (not shown). Pipe  12  is provided with a small opening  12   c  in a first region of the sidewall and a large opening  12   d  in a diametrically opposed region thereof. As will be seen, small opening  12   c  accommodates a shaft of the turbine therethrough, while large opening  12   d  accommodates turbine assembly  96  therethrough. Pipe  12  also is equipped with a flanged T-intersection pipe section (a so-called “tee”) that effectively mates large opening  12   d  at a right angle to the long axis of pipe  12 . 
     Generator cap assembly  14  includes a circular arched plate  18  that effectively acts to cover or close off larger opening  12   d  when system  10  is assembled. Arched plate  18  provides a contiguous round wall inside pipe  12  for the fluid to flow past, thereby avoiding cavitation or other smooth fluid flow disruption within what would otherwise act as a pocket volume within the tee section. A 3-vaned, cylindrical spacer  20  holds arched plate  18  in place within the tee section when a cover plate  22  including an annular seal  22   a  and a circular plate  22   b  is bolted onto flange  12   e . Circular plate  22   b  has an opening  22   ba  therein with a mounting block  24  extending therearound. A first mount  26  including a roller bearing assembly mounts a distal end of the shaft of turbine assembly  96  for smooth rotation therethrough. A flat shim  22   bb  can be provided between mounting block  24  and circular plate  22   b.    
     An alternative to the above circular plate  22   b  is illustrated in  FIGS. 6A and 6B , which are fragmentary cut-away side elevations featuring the interior of tee section  12   e . Those of skill in the art will appreciate that absolute and relative dimensions in  6 A and  6 B are not to scale, as they are for general structural comparison purposes. 
     A side-by-side comparison of  FIG. 6A , which features flat circular plate  22   b  described above, and  FIG. 6B , which features a spherically concave circular plate  22   b ′, reveals some important advantages of alternative plate  22   b ′. Flat circular plate  22   b  must be formed of relatively thick material, thereby rendering it heavy and difficult to handle. Spherically concave circular plate  22   b ′ on the other hand may be seen to be formed of relatively thin material, thereby rendering it significantly lighter in weight and significantly easier to handle. 
     This is by virtue of the curvature of alternative plate  22   b′.    
     Moreover, the central region of flat circular plate  22   b  may be seen to be farther from the turbine assembly, thus undesirably extending the length of the turbine&#39;s shaft. Conversely, the central region of spherically concave circular plate  22   b ′ may be seen to be closer to the turbine assembly, thereby desirably shortening the required length or vertical span of the turbine&#39;s shaft. 
     This too is by virtue of the curvature of alternative plate  22   b′.    
     From  FIG. 6B , concave plate  22   b ′ will be understood to be of generally spherical shape with the concavity extending inwardly from generator assembly (not shown for the sake of simplicity and clarity in this view) and toward the turbine assembly  96 ′ (shown only schematically in these detailed views by way of dash-dot-dot outlines, and the only difference from turbine assembly  96  being the provision of a shorter shaft  64 ′). This inward or downwardly oriented concave circular plate may be thought of and described herein as an inverted dome (or inverted cupola). While a spherically concave shape is illustrated and described, those of skill in the art will appreciate that suitable modifications can be made thereto without departing from the spirit and scope of the invention. For example, an inverted dome featuring a parabolic rather than a semi-circular cross section is possible, as are other curvilinear cross sections of various aspect ratios (i.e. of various depth-to-width ratios only one of which is shown with some intentional depth exaggeration for the sake of clarity). Also, the cupola-shaped plate in cross section can have a more rounded upper shoulder, producing what might be thought of as complex curvature. All such suitable alternative configurations are contemplated as being within the spirit and scope of the invention. 
     Those of skill in the art will appreciate that mounting details in such an alternative embodiment are modified straightforwardly to accommodate inverted cupola-shaped circular plate  22   b ′ and its bolted assembly through annular seal  22   a  onto standard flange  12   e  of pipe  12 . For example, mounting block  24 ′ may include a shim  22   bb ′ that is spherically convexly curved to mate and seal the spherically concave curvature of the inside of the inverted cupola. Generator  32  will be understood to mount to, for rotation with, the distal end of the turbine&#39;s shaft directly above the opening in the central region of spherical concave plate  22   b ′. Other components and techniques for accommodating alternative spherically concave circular plate  22   b ′ are contemplated as being within the spirit and scope of the invention. 
     A generator sub-assembly  28  bolts through a circular hole arrangement within circular plate  22   b . Generator sub-assembly  28  includes an annular spacer or standoff  30  for housing a generator  32  couple-able with the turbine&#39;s shaft, an annular rim  34  with a first mechanical-lift tab  34   a , and a cap  36  having a second mechanical-lift tab  36   a . Those of skill in the art will appreciate that tabs  34   a  and  36   a  provide convenient tabs for lifting all or part of the assembled tee-section electrical power generation components during assembly, disassembly, or maintenance. Those of skill will appreciate that the generator can be direct or alternating current (DC or AC) and single-phase or 3-phase, synchronized 120 VAC or 240 VAC, etc. and/or can be converted from one to the other, depending upon the power grid requirements. 
     A mounting plate  12   f  is welded to pipe  12  around small opening  12   c  and a second mount  38  including a roller-bearing assembly that mounts a distal end of the shaft of turbine assembly  96  for smooth rotation therein. Those of skill in the art will appreciate that, to accommodate the circular cross section of cylindrical pipe  12 , first mount  26  in accordance with one embodiment of the invention includes a shim (not shown in pertinent detail but believed to be understood from this brief description by those of skill in the art) having an exterior planar surface and an inner cylindrical surface for mating with the exterior cylindrical surface of the pipe. The shim can be machined or formed by any suitable process and of any suitable material that ensures conformingly sealing engagement between the shaft and the pipe opening through which the shaft extends. Either shim described and/or illustrated herein will be understood to be optional, as either can readily be incorporated into the corresponding mounting block or plate. 
     First and second mounts  26  and  38  can take alternative forms, within the spirit and scope of the invention, but it is believed that axial and radial thrust handling is best achieved using spherical roller bearings producing only rolling friction rather, for example, than sleeve bearings or other sliding friction arrangements. The roller bearing mounts described herein are believed to enable system  10  to operate safely, reliably and durably to produce electricity with a fluid flow rate through pipe  12  of as little as approximately 3-4 feet/second (fps). 
     Those of skill in the art will appreciate that turbine assembly  96  is slipped through large opening  12   d  of pipe  12  and the distal end of its shaft is secured to second mount  38 . Generator assembly  14  is bolted onto flange  12   e  of pipe  12  and the hydro-electric power system  10  is ready to operate. Power system  10  is fitted into or otherwise rendered onto a part of a pipe system (not shown). When fluid flows through pipe  12 , power system  10  generates electricity. 
     Surprisingly, it has been discovered that turbine assemblies such as that described and illustrated herein rotate at fluid flow rates as low as approximately 3-4 feet per second (fps). 
     Those of skill also will appreciate that the intentionally broad term “spheroidal” may be used instead of the term “spherical”, or vice versa, wherein a spheroidal turbine that was slightly or somewhat out-of-round or oval in cross section could be used productively within a correspondingly somewhat out-of-round or oval in cross section cylindrical pipe. These and other variations on the invention are contemplated as being within the spirit and scope of the invention. 
       FIG. 2  is a side elevation of assembled system  10 .  FIG. 2  is believed to be largely self-explanatory in view of the detailed description above by reference to  FIG. 1  to which it corresponds. It may be seen from  FIG. 2  that the ‘solidity’ of the spherical turbine assembly is between approximately 15% and 30%, depending upon the number of blades in the plurality and their individual configuration and pitch. It will be appreciated that the angle of intersection of each of the plurality of spherical turbine blades and the central axis of the shaft in accordance with one embodiment of the invention is approximately 30 degrees, although other angles are contemplated as being within the spirit and scope of the invention. For example, the angle of intersection alternatively but within the spirit and scope of the invention may be between approximately 10 and 45 degrees, or more preferably between approximately 15 and 35 degrees, or most preferably between approximately 25 and 35 degrees. Any suitable angles within any useful ranges are contemplated as being within the spirit and scope of the invention. 
     The embodiment illustrated herein is a four-blade spherical turbine assembly, but as few as two blades and as many as twenty blades are contemplated as being within the spirit and scope of the invention. More preferably, between approximately two and eleven blades are contemplated. Most preferably, between approximately three and seven blades are contemplated. Other numbers and configurations of approximately 180 degree arced spherical turbine blades are contemplated as being within the spirit and scope of the invention. Those of skill in the art will appreciate best perhaps from  FIG. 3  that the blades of the spherical turbine assembly are characterized along their entire length by airfoil cross section. This provides the turbine&#39;s hydrodynamics and efficiency at generating hydroelectric power. In accordance with this spherical-turbine embodiment of the invention, sufficient clearance around the rotating spherical turbine assembly and within the pipe is provided to avoid undue compression of fluid at the turbine sweep boundaries (see  FIG. 2 ). 
     Those of skill will appreciate that the spherical turbine blades, within the spirit and scope of the invention, can be made of any suitable material and by any suitable process. For example, the blades can be made of aluminum, a suitable composite, or a suitable reinforced plastic material. The blades can be made by rotational or injection molding, extrusion, pultrusion, bending, or other forming techniques consistent with the material used and consistent with the cost-effective production of elongated bodies having substantially constant cross sections. These and other useful materials and processes are contemplated as being within the spirit and scope of the invention. 
     In accordance with the illustrated embodiment of the invention, the air-foil cross section of the spherical turbine blades conforms with the recognized NACA 20 standard, although alternative air-foil cross sections are contemplated as being within the spirit and scope of the invention. 
       FIG. 3  is an isometric exploded assembly drawing of spherical turbine  96 . Spherical turbine  96  includes upper and lower hub assemblies  98  and  100 . Each hub assembly includes a hub plate  102  and four mounting brackets  104 ,  106 ,  108 , and  110  (only the upper hub assembly being so designated for the sake of clarity). Hub plate  102  is flat and features a sawblade-like (alternately curvilinear to follow the circular cross-sectional outline of the rotation and straight to permit abutment and flush mounting of the ends of the blades) peripheral edge the straight portions of which mount the mounting brackets as shown. The mounting brackets in turn mount four spherical blades  112 ,  114 ,  116 , and  118  each at a designated angle, e.g. preferably approximately 30 degrees, between the plane generally described by each curved blade and the central axis of the shaft. Those of skill in the art will appreciate that spherical blades  112 ,  114 ,  116 , and  118  also are of airfoil cross section, e.g NACA 20 or any other suitable standard. Upper and lower split shaft couplers  120  and  122  are used to securely affix the hub assemblies to the shaft  64 . In accordance with one embodiment of the invention, the mounting brackets bolted to the plural blades are affixed to the hub plates by welding, using the illustrated guide pins and holes for alignment. Suitable fasteners such as hex bolts, lock washers, and set screws are used to assemble the remaining component parts of spherical turbine assembly  96 , as illustrated. 
       FIG. 4  is an isometric view of assembled spherical turbine  96 .  FIG. 4  is believed to be largely self-explanatory in view of the detailed description above by reference to  FIG. 3  to which it corresponds. The dynamic clearance of the rotating spherical turbine assembly is greater than its static clearance, and is accommodated by slightly under-sizing the cylindrical turbine relative to the ID of the pipe, e.g. by providing a small but preferably constant clearance of between approximately 0.5 centimeters and 5 centimeters and preferably between approximately 1 centimeter and 3 centimeters, depending upon the diameter of pipe  12  and other application specifics. These spacings are illustrative only, and are not intended to be limiting, as alternative spacings are contemplated as being within the spirit and scope of the invention. 
       FIG. 5  illustrates the invented apparatus in accordance with another embodiment of the invention. Alternative system  10 ′ is similar to system  10  described above, and thus uses identical reference designators for identical components and primed reference designators for similar components. System  10 ′ may be seen further to include an upstream deflector  122  (for the sake of clarity,  FIG. 5  omits the turbine and generator assembly details). Deflector  122  in accordance with one embodiment is made of two or more flat expanses including a first, less-inclined expanse  122   a  that curvilinearly conforms to the interior circular cross section of pipe  12  and a second, more-inclined expanse  122   b  that creates a concavely curved inner free edge  122   ba  that extend toward and generally conforms with the circularly cross-sectional spherical turbine. The two expanses are welded or otherwise joined along a mating line that defines a break in their angles of inclination relative to the central axis of the pipe. Deflector  122  in operation of system  10 ′ thus effectively shields the outer rotational extent of the rotating blades of the spherical turbine in a rotational arc in which they are most weakly productive of energy and thus can produce undesirable stall at lower flow rates. 
     Surprisingly, it has been discovered that deflector  122  near an upstream region of turbine assembly  96  can increase the electrical energy production by between approximately 14% and 40% and more likely between approximately 20% and 30% over the nominal output of the spherical turbine without such an upstream deflector within the pipe. 
     Those of skill in the art will appreciate that the ratio between the deflector&#39;s coverage and the turbine&#39;s sweep can be between approximately 10% and 40% and more likely between approximately 20% and 30%. Those of skill in the art will also appreciate that the amount of deflector coverage may be application specific, as it represents a tradeoff between volumetric flow rate and head drop-off. Thus, alternative ranges of deflector coverage relative to turbine sweep are contemplated as being within the spirit and scope of the invention. 
     Those of skill also will appreciate that deflector  122  can be made of any suitable material, e.g. steel, and can be dimensioned and oriented for any desired fluid flow adjustment in the upstream region of spherical turbine assembly  96 . In accordance with one embodiment of the invention, deflector  122  is inclined relative to the long central axis of pipe  12  at an angle of less than 90 degrees at its free edge  122   ba . A so-called exit angle of the deflector&#39;s free edge relative to the central axis of pipe  12  preferably is between approximately 10 degrees and 40 degrees. In accordance with one embodiment of the invention, expanse  122   a  is inclined at approximately 15 degrees and expanse  122   b  is inclined at approximately 30 degrees from the central axis of pipe  12 . Nevertheless, other inclined angles are contemplated as being within the spirit and scope of the invention. 
     Those of skill in the art will appreciate that deflector  122  can take different forms within the spirit and scope of the invention. For example, deflector  122  can have more and shorter piece-wise planar segments than two as it radiates inwardly toward the central axis of pipe  12 , thus better approximating a smooth, and preferably circular-cylindrical curve the central axis of which is preferably approximately parallel with the turbine&#39;s axis of rotation (i.e. approximately parallel with the long axis of shaft  64 ). Indeed, deflector  122  within the spirit and scope of the invention can be smoothly cylindrically curved between its pipe-mating edge and its free edge. 
     The free edge  122   ba  of deflector  122  in accordance with one embodiment of the invention is concavely curved generally to conform its inward extent along its height with the general curve of the blades of the spherical turbine. Any suitable rectilinear or smooth curve or radius of curvature is contemplated as being within the spirit and scope of the invention. 
     Those of skill in the art will appreciate that the spherical turbine can serve in power conversion systems other than electric power generation. For example, axial kinetic energy of a fluid can be converted to rotating kinetic energy for any rotating machinery (e.g. a conveyor, a grinder, a drill, a saw, a mill, a flywheel, etc.) including an electric generator or suitable alternative. All such uses of the invented fluid turbine are contemplated as being within the spirit and scope of the invention. 
     Those of skill in the art will appreciate that orientation of the invented system in its many embodiments is illustrative only and should not be read as a limitation of the scope of the invention. Thus, use of terms like upper and lower will be understood to be relative not absolute, and are interchangeable. In other words, the system can assume either vertical orientation, within the spirit and scope of the invention, with the bulkhead housing the generator and the turbine shaft extending relative to the long axis of the pipe either up or down. Indeed, the system can assume any other suitable angle in which the shaft of the turbine extends approximately perpendicular to the direction of the fluid flow. 
     Those of skill in the art will appreciate that component parts of the invented systems can be made of any suitable material, including steel and aluminum. Most parts can be steel, for example, as are the turbine shafts, flat plates, and deflector. Remaining parts including hubs, coupling blocks, and blades can be made of machined, extruded, or pultruded aluminum (the blades then being roll-formed and/or bent into the desired form) or injection-molded, reinforced plastic. Any alternative material and any alternative forming process is contemplated as being within the spirit and scope of the invention. 
     Those of skill will also appreciate that the invented systems are of easily scaled dimension up or down, depending upon their application. So that while dimensions generally are not given herein, dimensions will be understood to be proportionately accurately illustrated, the absolute scale of which can be varied, within the spirit and scope of the invention. 
     Those of skill in the art will appreciate that two or more hydro-electric power generation systems can be installed at defined intervals (in series) within and along a water conveying pipe, thereby to multiply power generation. Those of skill in the art also will appreciate that parallel arrangements of two or more hydro-electric power generation systems can be installed within branches of a water conveying pipe, thereby alternatively or additionally to multiply power generation. Those of skill in the art will appreciate that kick-start mechanisms can be added to the hydro-electric power generation systems described and illustrated herein, if needed, for use of such systems in tidal (bidirectional, oscillating) flow applications. Those of skill will also appreciate that fail-safe modes of operation can be achieved in the use of the invented in-pipe hydro-electric power generation systems to prevent self-destruction in the event of bearing failure or the like. Finally, those of skill in the art will appreciate that such hydroelectric power generation systems as are described and illustrated herein can be placed within an exterior sleeve conduit that protects the power generation system from the elements and/or that facilitates power distribution along power cables or other suitable conveyances to nearby storage devices or power grids. 
     It will be understood that the present invention is not limited to the method or detail of construction, fabrication, material, application or use described and illustrated herein. Indeed, any suitable variation of fabrication, use, or application is contemplated as an alternative embodiment, and thus is within the spirit and scope, of the invention. 
     It is further intended that any other embodiments of the present invention that result from any changes in application or method of use or operation, configuration, method of manufacture, shape, size, or material, which are not specified within the detailed written description or illustrations contained herein yet would be understood by one skilled in the art, are within the scope of the present invention. 
     Accordingly, while the present invention has been shown and described with reference to the foregoing embodiments of the invented apparatus, it will be apparent to those skilled in the art that other changes in form and detail may be made therein without departing from the spirit and scope of the invention as defined in the appended claims.