Patent Publication Number: US-11022001-B2

Title: Methods and apparatus to adjust hydrodynamic designs of a hydrokinetic turbine

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This patent arises from a divisional of U.S. patent application Ser. No. 14/842,662 (now U.S. Pat. No. 10,107,143), which was filed on Sep. 1, 2015, and is hereby incorporated herein by reference in its entirety. 
    
    
     FIELD OF THE DISCLOSURE 
     This disclosure relates generally to hydrokinetic turbines and, more particularly, to methods and apparatus to adjust hydrodynamic designs of a hydrokinetic turbine. 
     BACKGROUND 
     A hydrokinetic turbine captures energy from a flow of water to drive a generator to generate electricity that can be used on nearby land. Hydrokinetic turbines are typically placed in bodies of waters such as rivers and streams. Water flow characteristics such as velocity or flow patterns can differ across bodies of waters as well as within a body of water between a first position and a second position. The design of one or more components of a hydrokinetic turbine may be based on one or more characteristics of the body of water in which the turbine is to be placed. 
     SUMMARY 
     An example turbine to be placed in a body of water includes a generator having a frame, an inlet, a first set of vanes disposed in the inlet, a second set of vanes, and a shroud. The inlet, the first set of vanes, the second set of vanes, and the shroud are removably coupled to the frame. The first set of vanes in removably coupled to the inlet. 
     An example hydrokinetic turbine includes a generator having a frame, a shroud removably coupled to the frame, an inlet removably coupled to the frame, a first set of vanes having a first geometry, and a second set of vanes having a second geometry. Each of the first set of vanes and the second set of vanes is configured to be removably coupled to the inlet. In the example hydrokinetic turbine, one of the first set of vanes or the second set of vanes is to be selectively coupled to the inlet based on the first geometry or the second geometry. 
     Another example turbine to be placed in a body of water includes an inlet to receive a flow of the water, a shroud to provide an outlet for the flow of the water, and a generator to provide a frame. The inlet and the shroud are removably coupled to the frame. The example turbine includes means for adjusting a velocity of the flow of the water. The means for adjusting the velocity is removably coupled to the frame. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is an example hydrokinetic turbine constructed in accordance with the teachings disclosed herein. 
         FIG. 2  is an exploded view of portions of the hydrokinetic turbine of  FIG. 1 . 
         FIG. 3  is an exploded view of example components of the hydrokinetic turbine of  FIGS. 1 and 2 . 
         FIG. 4  is a flow diagram of an example method for constructing a hydrokinetic turbine from selective hydrodynamic components. 
     
    
    
     The figures are not to scale. Instead, to clarify multiple layers and regions, the thickness of the layers may be enlarged in the drawings. Wherever possible, the same reference numbers will be used throughout the drawing(s) and accompanying written description to refer to the same or like parts. 
     DETAILED DESCRIPTION 
     A hydrokinetic turbine converts kinetic energy from flowing water into mechanical energy that rotates a shaft. The mechanical energy is used to drive a generator to create electrical energy. Hydrokinetic turbines are placed in bodies of water such as oceans, rivers, and streams, and use tidal waves or water currents to generate electricity without requiring the building of, for example, dams. Thus, hydrokinetic turbines provide a relatively low-cost means of generating electricity with minimal impact to the environment. 
     To efficiently capture a maximum amount of kinetic energy from flowing water, components of a hydrokinetic turbine are designed based on characteristics of the body of water in which the turbine is to be placed and, in particular, characteristics of a location or position in the body of water at which the turbine is to be installed. An example characteristic of a body of water such as a river is a velocity at which the river water flows. Increased velocity corresponds to increased kinetic energy of the water and, thus, increased power when that energy is captured by the hydrokinetic turbine. For example, a hydrokinetic turbine may be placed in a river having a velocity at or above approximately 2 knots (approximately 1 meter/second). 
     The velocity of water changes between positions within a body of water. For example, river water changes velocity along the course of the river due to factors such as a shape of the river (e.g., curvature, width), water volume, a gradient of the river, and objects such as rocks found in the water flow path. Thus, a velocity of flowing water measured at a first position in the river may differ from a velocity of water measured at a second position in the river (e.g., upstream or downstream relative to the first position, a position across the width of a body of water). Therefore, although components of a hydrokinetic turbine such as blades and an inlet diameter may be designed to efficiently capture the kinetic energy of the water at the first position, the same turbine component designs may not work as efficiently at the second position due to the change in velocity between the first and second positions. Generally, for every change in water velocity greater than one-half knot (e.g., Δv&gt;½ knot), the design of one or more components of the turbine is modified to operate efficiently at the changed velocity range. Thus, installing a plurality of hydrokinetic turbines along a course of a river can require several differently designed hydrokinetic turbines depending on the changes in water velocity along the course of the river. 
     Prior to installing one or more hydrokinetic turbines in a body of water such as a river, the water velocities at various positions along the river are measured to create a map of the river based on river velocity ranges. A complete hydrokinetic turbine (e.g., including a generator, an inlet, blades, a shroud, etc.) is then designed and built for each river velocity range (or selected from pre-built complete turbines). As each turbine is made for a particular velocity range, a turbine cannot be easily repositioned along a river or placed in a different river velocity range if the turbine is not designed for that river velocity range. Rather, a new turbine is ordered and built for the particular river position and velocity range. 
     Turbines are typically constructed from integrally cast pieces formed of metal such as ductile iron. For example, molds are built for components such as an inlet portion of the turbine and a shroud portion of the turbine. The molded components are bolted together in a factory or on a shore near the water in which the turbine is to be installed. The turbine is then placed on a barge for delivery to the location in the water where the turbine is to be installed. If the turbine needs to be repositioned or if the water velocity range changes over a threshold amount, new molds may need to be built for casting turbine components that are designed for the water velocity range at the location where the turbine is to be moved to or for the changed water velocity range. A new turbine, including a generator section, is built with the newly casted components for delivery from, for example, a factory, to the water site. 
     The components of known turbines typically include one or more integrated parts. For example, drive vanes, which rotate about the shaft of the generator to drive the generator, are typically integrated with the generator. Also, an inlet portion of the turbine can include blades or vanes that are cast or integrated with an inlet frame. Thus, certain components of these known turbines, such as the drive vanes and the inlet vanes cannot be replaced to account for changes in water velocity or for maintenance without replacing the inlet assembly, the generator assembly, or the entire turbine. 
     Example methods and apparatus disclosed herein substantially eliminate the need for customized building of complete hydrokinetic turbines for each water velocity range of a body of water by providing a common generator section that can be used in substantially any velocity range and to which different designs for the intake, blades, and shroud can be removably coupled based on the velocity range at the location where the turbine is to be installed. In the examples disclosed herein, the components, including the drive vanes and inlet blades, are separable parts relative to each other and the generator section. The components are removably coupleable to a frame or skeleton of the common generator section. For example, an inlet portion having a first geometry, or diameter, can be replaced with an inlet portion having a second geometry, or (e.g., larger) diameter or other shape feature, for use with the same generator section. A first set of drive vanes having blades with a first geometry, or width or angle, can be replaced with a second set of drive vanes having blades with a second geometry, or width or angle, without having to replace the generator section of the turbine. Similarly, the inlet blades can be replaced without requiring replacement of the inlet portion of the turbine. Also, in the examples disclosed herein, one or more of the components may be formed from materials such as fiberglass or carbon fiber or any other or non-metallic material or any other non-cast material, which reduces the weight of the turbine structure as compared to cast metal pieces and facilitates ease of assembly and disassembly. 
     Thus, rather than building custom turbines for each velocity range, in the examples disclosed herein, differently designed or configured turbine components are selectively coupled to the common generator section based on turbine design characteristics or geometries particular to a water flow velocity at a particular turbine installation location. Example design characteristics or geometries include inlet diameter, blade width, shroud diameter, a degree of blade curvature (e.g., twist or angle), material thickness, etc. Therefore, a user can change the position of a turbine within the body of water without having to order a complete new turbine but, rather, by changing one or more components (e.g., having different geometric design properties or profiles) coupled to the generator section. The ability to modularly assemble the turbines at or near the installation location simplifies the assembly and installation process when a plurality of turbines are to be installed. Further, the example turbine disclosed herein can be modified to adjust to changes in water velocity over time (e.g., due to erosion or deposition in the body of water) or for maintenance by replacing one or more of the components with differently configured components rather than replacing the whole turbine, including the generator. Also, the selective coupling and decoupling of the turbine components can be performed on-site (e.g., on a barge in the water proximate to the installation location of the turbine) when the turbine is removed from the water rather than having to return the turbine to the shore or a factory to be reconfigured. 
       FIG. 1  is an example hydrokinetic turbine  100  including a generator  102 , an inlet  104 , and a shroud  106 . To install the turbine  100  in a body of water such as a river, the generator  102 , the inlet  104 , and the shroud  106  are coupled (e.g., bolted) to a base  108 . The inlet  104  has an inlet diameter  110 . An opening of the shroud  106  opposite the inlet  104  forms an outlet  112  of the turbine. The outlet  112  of the shroud  106  has an outlet diameter  114 . 
     As water flows through the inlet  104  and out the outlet  112 , the velocity of the water (e.g., a speed of the water along an axis of the turbine  100  between the inlet  104  and the outlet  112 ) changes based on a cross-sectional area of the inlet  104  and a cross-sectional area of the outlet  112  (e.g., Δv=v outlet −v inlet , where v outlet  is the velocity of the water at the outlet  112  and v inlet  is the velocity of the water at the inlet  104 ). Changing the cross-sectional area of the inlet  104  and the cross-sectional area of the outlet  112  by adjusting the size of the respective inlet and outlet diameters  110 ,  114  changes the velocity of the water. For example, water flows at an increased velocity through smaller diameters. Thus, the change in velocity Δv of the water flowing between the inlet  104  and the outlet  112  is a function of the respective inlet and outlet diameters  110 ,  114  of the inlet  104  and the outlet  112 . Therefore, the geometries of the inlet  104  and/or the outlet  112 , such as the size of the respective diameters  110 ,  114 , can be changed to regulate the velocity of the water through the turbine  100 . 
     In the example turbine  100 , the inlet diameter  110  and the outlet diameter  114  are sized to slow the velocity of the water as the water flows between the inlet  104  and the outlet  112 . Reducing the water velocity reduces, for example, turbulence of the water to efficiently capture the energy from the flowing water to drive the turbine  100 . To reduce the water velocity, the shroud  106  is configured to expand the flow of water relative to the inlet  104 , thereby allowing the water flow to slow down. For example, the outlet diameter  114  can be larger than the inlet diameter  110  such that as the water flows toward the shroud  106 , the cross-sectional area through which the water flows increases, thereby changing (e.g., reducing) the velocity of the water. 
     The sizes of the inlet diameter  110  and the outlet diameter  114  can be based on, for example, the velocity of the water at the location where the turbine  100  is to be installed and a change in velocity (e.g., a predetermined value of Δv) to be achieved as the water flows through the turbine  100  to drive the turbine  100 . To selectively change the velocity of the water flowing through the turbine  100 , the inlet  104  and the shroud  106  are selected based on their respective diameters  110 ,  114  to obtain cross-sectional areas through which the water flows that result in the desired change in velocity Δv. For example, the inlet  104  and/or the shroud  106  may be pre-built components that can be selected from a range of inlets and shrouds having different diameters. 
     The selected inlet  104  and the shroud  106  are removably coupled to the generator  102  via mechanical fasteners such as bolts, studs, and/or other fastening devices. For example, the inlet  104  is removably coupled to the generator  102  at a first edge  116  (e.g., a first circumferential edge) of the generator  102 . The shroud  106  is removably coupled to the generator  102  at a second edge  118  (e.g., a second circumferential edge) of the generator  102  opposite the first edge  116 . Also, the generator  102 , the inlet  104 , and the shroud  106  can be removably coupled (e.g., via mechanical fasteners) to the base  108  for installation in a body of water. 
     Thus, the generator  102  of the example turbine  100  is adapted to receive inlets and shrouds having different geometries depending on the change in velocity Δv to be achieved, thereby resulting in a customized turbine  100  built from pre-fabricated, removable components. If, for example, the turbine  100  is to be moved from a first location to a second location in the body of water and the water at the second location has a different velocity than at the first location, the inlet  104  and/or the shroud  106  can be decoupled from the generator  102  and the base  108  (e.g., by removing the mechanical fasteners). The inlet  104  and/or the shroud  106  can then be replaced with an inlet and/or a shroud having respective diameters that result in a change in velocity Δv that efficiently drives the generator  102  in view of the installation of the turbine  100  at the second location, rather than ordering and/or building a complete new turbine including a generator section. 
     The inlet diameter  110  and the outlet diameter  114  are configured to result in a change in velocity as the water flows between the inlet  104  and the outlet  112 . To obtain the change in velocity Δv, the turbine  100  includes blades or vanes to reduce turbulent flow and resistance and increase efficiency.  FIG. 2  is an exploded view of the example hydrokinetic turbine  100  of  FIG. 1  including an intake portion  200  and the generator  102 . The intake portion  200  includes the inlet  104 , inlet or pre-swirl vanes  202 , drive vanes  204 , a static or non-moving support ring  206 , and a shaft  208 . The drive vanes  204 , which are proximate to the generator  102  and distal to the pre-swirl vanes  202  relative to the inlet  104 , rotate about the shaft  208 . The generator  102  includes generator vanes  210  to support the shaft  208  in examples where the shaft  208  is supported by two bearings. However, in some examples, the generator  102  does not include the generator vanes  210 . As will be disclosed below, the inlet  104 , the pre-swirl vanes  202 , and the drive vanes  204  are removably coupled to the generator  102 . In some examples, the shaft  208  and the generator  102  provide a common skeleton or frame to which the inlet  104 , the pre-swirl vanes  202 , and the drive vanes  204  are removably coupled. 
     The pre-swirl vanes  202  and the drive vanes  204  provide for efficient conversion of hydrokinetic power by orienting the water as it flows into the inlet  104  to the generator  102 . The flow of water in a body of water may not be uniform and can include, for example, vortices that result in increased resistance and turbulence. The pre-swirl vanes  202  swirl the incoming water to a predetermined degree of swirl based on geometric design properties of the pre-swirl vanes  202 . For example, design properties of the pre-swirl vanes  202  such as a shape of the individual vanes or blades, a degree of curvature of the vanes (e.g., twist), a width of the vanes, a thickness of the vanes, a number of the vanes, and an amount of spacing between the vanes can affect the flow pattern of the water moving into and through the turbine  100 . In some examples, the pre-swirl vanes  202  are at least partially housed within a circumference of the inlet  104  and, thus, are encountered as the water flows into the inlet  104 . 
     The pre-swirl vanes  202  reduce variations in the water flow and orient the water by creating a substantially uniform flow (e.g., as a rotating vortex). Thus, the pre-swirl vanes  202  reduce flow resistance and turbulence, thereby increasing the operational efficiency of the turbine  100 . Pre-swirling the water to substantially eliminate or reduce turbulence in the water before the water encounters the generator  102  increases the efficiency of the operation of the generator  102  in capturing hydrodynamic power. 
     As the water flows past the pre-swirl vanes  202 , the water impinges on the drive vanes  204 . Similar to the geometric design characteristics of the pre-swirl vanes  202 , geometric design properties of the drive vanes  204  include blade shape, degree of curvature, size, number, etc. The drive vanes are disposed in a rim  212 . Also, the drive vanes  204  are removably coupled to a drive vane frame  214 , which is coupled to the shaft  208  such that the drive vanes  204  rotate with the shaft  208 . 
     In the example turbine  100 , the rim  212 , including the drive vanes  204 , is located within the static support ring  206 . The design properties of the support ring  206 , such as a diameter and thickness of the support ring  206 , can be associated with the design properties of the rim  212 , the drive vanes  204 , and/or the inlet  104 . For example, a diameter of the support ring  206  may be selected to accommodate the rim  212  and the drive vanes  204  within a circumference of the support ring  206  while being sized such that the inlet  104  can overlay or house the support ring  206  when the inlet  104  is coupled to the generator  102 . In some examples, the support ring  206  is coupled to at least a portion of a frame or skeleton formed by the drive vanes  204 . In operation, the drive vanes  204  rotate and cause the shaft  208  to rotate, which in turn drives the generator  102 . In particular, the rim  212  includes one or more magnets. The support ring  206  can include, for example, a copper material such that rotation of the drive vanes  204  and the rim  212  within the support ring  206  generates power from the resulting magnetic field. 
     In some examples, the design properties or geometries of the pre-swirl vanes  202  and the drive vanes  204  such as a degree of curvature or angle are selected based on, for example, the desired change in velocity Δv. The pre-swirl vanes  202  and the drive vanes  204  can facilitate the extraction of the change in velocity Δv from the water flowing through the vanes  202 ,  204 . In particular, whereas the diameter of the inlet  104  (e.g., the diameter  110  of  FIG. 1 ) and the diameter of the outlet  112  of the shroud  106  (e.g., the diameter  114  of  FIG. 1 ) determine the change in velocity Δv of the water flowing through the turbine  100 , the pre-swirl vanes  202  and/or the drive vanes  204  optimize performance to achieve the predetermined change in velocity Δv as the water flows between the inlet  104  and the outlet  112 . For example, the vanes  202 ,  204  impact the velocity of the water by reducing turbulent flow and changing or partially changing the flow of the water (e.g., causing an angular deviation via pre-swirling), which contributes to the overall change in velocity Δv. Thus, changing the design properties of the flow contact surfaces encountered by the flowing water such as the vanes  202 ,  204  can increase efficiency of the turbine  100  in achieving the desired change in velocity Δv of the water. 
     In some examples, the pre-swirl vanes  202  and the drive vanes  204  are made of a carbon fiber material to reduce the weight of the individual blade components and to facilitate ease of assembly. Further, any of the removable components disclosed in connection with the turbine  100 , including the inlet  104 , the shroud  106 , the pre-swirl vanes  202 , the drive vanes  204 , and the support ring  206 , can be formed from materials such as fiberglass, carbon fiber, concrete, fiber-infused concrete, and/or a composite material. Thus, the weight of the overall turbine  100  is reduced as compared to turbines constructed from one or more integrally cast metal components. 
     As disclosed above, the generator  102  provides a common skeleton or frame to which the inlet  104  and the vanes  202 ,  204  can be removably coupled (e.g., via mechanical fasteners such as bolts). The inlet  104 , the vanes  202 ,  204 , and the support ring  206  can be oriented about the shaft  208  such that the shaft  208  serves as a center bar structure for coupling the removable components to the generator  102 . Further, the support ring  206  can provide an interface between the generator  102  and the inlet  104  to couple the inlet  104  to the generator  102 . For example, the inlet  104  can extend over the support ring  206  at the point of coupling to the generator  102  (e.g., at the first edge  116  of the generator  102  as illustrated in  FIG. 1 ). 
     Selectively coupling the inlet  104 , the shroud  106 , the pre-swirl vanes  202 , the drive vanes  204 , and the support ring  206  to the generator  102  results in the turbine  100 , which is customized for the location in the body of water in which the turbine  100  is to be installed. In particular, the selective coupling of the aforementioned components based on hydrokinetic design properties of the components adapts the generator  102 , to the body of water and the location at which the generator  102  is to operate. Thus, although the design of the generator  102  may be static or fixed, the overall design of the turbine  100  can be dynamically adjusted for different water flow rates by selectively coupling the inlet  104 , the shroud  106 , the pre-swirl vanes  202 , and the drive vanes  204  to the generator  102  based on design properties of these removable components. 
     The modular design of the turbine  100  provides for increased flexibility with respect to assembly and disassembly of the turbine  100 . If the water flow rate at the location where the turbine  100  is installed changes such that one or more of the components of the turbine  100  such as the inlet  104 , the shroud  106 , the pre-swirl vanes  202 , and/or the drive vanes  204  are no longer operationally efficient with respect to obtaining the desired change in velocity Δv, the one or more components can be selectively removed and replaced with components having different design properties or characteristics selected based on the change in water flow rate. Further, because, for example, the pre-swirl vanes  202  are not integrally formed with the inlet  104 , different sets of pre-swirl vanes  202  can be used with the same inlet  104 . Similarly, different sets of drive vanes  204  can be used with the generator  102 . Also, if the turbine  100  is to be moved from a first location to a second location, one or more of the components can be decoupled to facilitate ease of movement of the turbine. The one or more components can be re-coupled or replaced at the second location depending on the properties of the water at the second location. Thus, rather than building a new turbine to be installed at the second location, the generator  102  can be easily reconfigured for use at the second location. 
       FIG. 3  is an exploded view of example components of the example hydrokinetic turbine  100  of  FIGS. 1 and 2 . In particular,  FIG. 3  illustrates that one or more components of the example hydrokinetic turbine  100  are modular in design such that two or more pieces are coupled together to form the component. The modular design of the components of the example hydrokinetic turbine  100  facilitates ease of selective assembly and disassembly of the components for maintenance purposes and/or to address changes in water flow characteristics. 
     As illustrated in  FIG. 3 , the inlet  104  can include two or more inlet pieces, parts or sections  300  removably coupled (e.g., mechanically fastened) together to form the inlet  104 . For illustrative purposes, one of the inlet pieces  300  is shown removed from the inlet  104  in  FIG. 3 . The inlet pieces  300  of the example inlet  104  include curved exterior surface pieces having design properties (e.g., size, shape, curvature) based on, for example, the desired inlet diameter  110  ( FIG. 1 ) of the inlet  104 . The inlet pieces  300  can be selectively uncoupled from one another for maintenance or to be replaced with other inlet pieces  300 . Also, as disclosed above in connection with  FIGS. 1 and 2 , the inlet  104  is removably coupled to the generator  102  (e.g., via the inlet pieces  300 ). The inlet  104  can be selectively coupled or uncoupled from the generator  102  as an integral component formed from the inlet pieces  300  or by selectively coupling or uncoupling the inlet pieces  300  from the generator  102 . 
     In some examples, the number of the inlet pieces  300  of the inlet  104  corresponds to the number of pre-swirl vanes  202  disposed in or proximate to the inlet  104 . As shown in  FIG. 3 , the pre-swirl vanes  202  include pre-swirl vane parts  302  removably coupled to an inlet center frame  304 . Although five pre-swirl vane parts  302  are shown disposed in the inlet  104  of in the example hydrokinetic turbine  100  of  FIGS. 1-3 , the hydrokinetic turbine  100  can include additional or fewer pre-swirl vane parts  302  based on, for example, a predetermined degree of swirl to be achieved in the water flowing through the inlet  104 . For example, for illustrative purposes,  FIG. 3  shows two additional pre-swirl vane parts  302 , one or both of which could be coupled to the inlet center frame  304 . Also, one or more of the pre-swirl vane parts  302  can be selectively uncoupled from the inlet center frame  304  to replace and/or repair the one or more pre-swirl vane parts  302  in view of, for example, wear and tear on the pre-swirl vane parts  302  from exposure of the pre-swirl vane parts  302  to water during operation of the example hydrokinetic turbine  100 , or damage incurred during transportation or initial assembly of the turbine before installation in the body of water. 
     In the example hydrokinetic turbine  100  of  FIG. 3 , the drive vanes  204  include two or more drive vane parts  306  removably coupled to the drive vane frame  214 . In the example hydrokinetic turbine  100 , the drive vane parts  306  are also coupled to the rim  212 . In some examples, the rim  212  is formed of an integral piece. In other examples, the rim  212  can be formed from two or more pieces. 
     Also, although the example hydrokinetic turbine  100  of  FIGS. 1-3  includes four drive vane parts  306 , the hydrokinetic turbine  100  can include additional or fewer drive vane parts  306 . For example, for illustrative purposes,  FIG. 3  shows two additional drive vane parts  306 , one or both of which could be coupled to the drive vane frame  214 . One or more of the drive vane parts  306  can be selectively removed or replaced as substantially disclosed above in connection with the pre-swirl vane parts  302 . 
     The inlet center frame  304  and the drive vane frame  214  are removably coupled to the shaft  208  ( FIG. 2 ) such that the pre-swirl vane parts  302  and the drive vane parts  306  rotate about the shaft  208 . As disclosed above in connection with  FIGS. 1 and 2 , water flows through the inlet  104  and is rotated by the pre-swirl vanes  204  (e.g., the pre-swirl vane parts  302 ) and the drive vanes  204  (e.g., the drive vane parts  306 ) as the water flows toward and through the generator  102 . As also disclosed above in connection with  FIGS. 1 and 2 , the water flows between the inlet  104  and the outlet  112  of the shroud  106  of the example hydrokinetic turbine  100 . In the example hydrokinetic turbine  100  of  FIGS. 1-3 , the shroud  106  is a modularly designed component of the turbine  100 . 
     For example, the shroud  106  can include two or more shroud pieces  312  coupled (e.g., bolted) together to form the cylindrical or substantially cylindrical shape of the shroud  106 . In some examples, the shroud pieces  312  are exterior surface pieces coupled to an interior shroud skeleton or frame. Design characteristics of the shroud pieces  312  (e.g., shape, curvature, etc.) are based on, for example, the desired diameter  114  of the outlet  112  of the shroud  106 . The shroud pieces  312  can be selectively uncoupled from one another for maintenance or to be replaced with other shroud pieces  312 . 
     In the example hydrokinetic turbine  100 , the shroud pieces  312  are removably coupled to one another and the generator  102 . The shroud  106  can be selectively coupled or uncoupled from the generator  102  as an integral component formed from the shroud pieces  312  or by selectively coupling or uncoupling the shroud pieces  312  from the generator  102 . Thus, the modular design of the shroud  106  with respect to the shroud pieces  312  facilitates ease of assembly and disassembly. Also, as the shroud pieces  312  of the example hydrokinetic turbine  10  are formed from, for example, carbon fiber, the modular design of the shroud  106  also reduces the weight of the shroud  106  and, thus, the turbine  100 , as compared to large integrally cast metal shrouds. 
       FIG. 4  is a flowchart of an example method  400  for generating hydrodynamic power and building a customized turbine from turbine components having hydrodynamic designs or properties selected based on properties such as water velocity. The example method  400  includes measuring (e.g., via a flowmeter) a water velocity range at a first position or location within a body of water at which a turbine (e.g., the turbine  100  of  FIGS. 1-3 ) is to be installed (block  402 ). The body of water may be, for example, a river, and the first position may be a location along the course of the river where the turbine is to generate electricity for use on nearby land. In some examples, velocity is measured at several positions in the body of water (e.g., along the course of the river) to create a map of water velocity ranges for the body of water. In such examples, a position at which the turbine is to be installed may be selected based on the map. 
     Based on the measurement of water velocity at the first position, the example method  400  includes selecting one or more turbine components for the turbine (block  404 ). The turbine components can include, for example, an inlet (e.g., the inlet  104  of  FIGS. 1-3 , the inlet pieces  300  of  FIG. 3 ), a shroud (e.g., the shroud  106  of  FIGS. 1 and 3 , the shroud pieces  312  of  FIG. 3 ), pre-swirl vanes (e.g., the pre-swirl vanes  202  of  FIGS. 2 and 3 , the pre-swirl vane parts  302  of  FIG. 3 ), and drive vanes (e.g., the drive vanes  204  of  FIGS. 2 and 3 , the drive vane parts  306  of  FIG. 3 ). In view of the measured water velocity, the one or more turbine components are selected based on design properties or characteristics of the components that achieve a predetermined change in velocity Δv as the water flows between the inlet of the turbine (e.g., the inlet  104 ) and an outlet of the turbine (e.g., the outlet  112  of the shroud  106 ). As disclosed above, the velocity of water flowing through a turbine can be adjusted (e.g., reduced) to capture the kinetic energy of the water to drive the turbine. In particular, in the example method  400 , such an adjustment can be achieved in view of the water velocity measurement at the first location by selecting turbine components based on design properties of the components such as diameter with respect to the inlet and shroud outlet and blade curvature and count with respect to the pre-swirl vanes and drive vanes. 
     The example method  400  includes coupling the selected turbine components to a turbine frame (block  406 ). The turbine frame includes a generator (e.g., the generator  102  of  FIGS. 1-3 ) and a shaft (e.g., the shaft  208  of  FIG. 2 ) to drive the generator. In the example method  400 , the turbine frame or skeleton is a common generator section in that the generator can operate in any or substantially any velocity range of a body of the water. In the example method  400 , the selected components are removably coupled to the common generator section to customize the turbine for installation at the first position in view of the water velocity range at the first position. Put another way, the common generator section or turbine frame is adapted for use at the first position based on the coupling of the turbine components selected for the measured velocity range to the frame. As disclosed above in connection with  FIG. 3 , in some examples, coupling the turbine components to the turbine frame can include coupling one or more modular pieces of a respective turbine component to another modular piece of the turbine component (e.g., the inlet pieces  300  of the inlet  104  of  FIG. 3 ). In such examples, the turbine component can be coupled to the turbine frame in a modular manner (e.g., via the individual pieces or parts such as the inlet pieces  300  of  FIG. 3 ) or as an integral component (e.g., the inlet  104  is assembled from the inlet pieces  300  and the inlet  104  is coupled to the turbine frame as an integral component). 
     The turbine components can be removably coupled to the turbine frame via one or more mechanical fasteners. For example, the inlet, the pre-swirl vanes, and the drive vanes can be coupled to turbine frame proximate to an intake portion of the generator. The shroud can be coupled to the turbine frame opposite the generator intake portion to provide an outlet. Once the turbine is assembled, the turbine is installed in the body of water at, for example, the first position (block  408 ). 
     In the example method  400 , after the turbine is installed at the first position, a decision may be made to move the turbine to a second position in the body of water and/or to replace the turbine components (block  410 ). For example, the turbine may be moved to the second position to generate electricity for nearby land at the second position. In other examples, one or more of the turbine components may be replaced due to wear. In some examples, the components are replaced due to a change in the water velocity at the first position over a threshold (e.g., a change in velocity over half a knot from the original measured water velocity range) such that the original components are no longer effective or efficient in achieving the change in velocity Δv. 
     If a decision is made to move the turbine and/or replace the turbine parts, the example method  400  includes measuring the water velocity range at the first position (e.g., re-measuring the water velocity range at the first position) or measuring the water velocity range at the second position (block  412 ). In examples where one or more of the turbine components are to be replaced but the turbine is to remain installed at the first position, re-measuring the water velocity range at the first position can verify that water velocity range at the first position has not changed or has not substantially changed over time (e.g., due to deposition) such that the selected design of the one or more turbine components is no longer appropriate for the turbine in achieving or efficiently achieving the predetermined change in velocity. In examples where the turbine is to be moved to a second position in the body of water, the water velocity range is measured at the second position to determine whether the water velocity range is different at the second position as compared to the first position. In both examples (i.e., replacing the turbine component(s) at the first position or moving the turbine to the second position), measuring the water velocity range provides for an opportunity to evaluate the design selection of the one or more turbine components in view of the measured water velocity. 
     To move the turbine or to replace one or more of the turbine components, the presently attached component or components are selectively decoupled from the turbine frame (block  414 ). In some examples, the components are selectively decoupled in a piecemeal manner based on the modular design of the components (e.g., the shroud pieces  312  of the shroud  106 ). When moving the turbine to a second position, decoupling the components and/or the modular parts of pieces of the components from the turbine frame facilitates ease of movement as compared to turbines built out of one or more integrally casted components. With respect to replacing one or more of the turbine components, for example, for maintenance purposes, selective decoupling of the turbine components allows for targeted maintenance in that rather than replacing the entire turbine, including the generator section, the components needing replacement can be decoupled from the turbine frame and replaced. 
     After decoupling the one or more turbine components from the turbine frame, the example method  400  returns to selecting turbine components to couple to the turbine frame based on the measured water velocity range (e.g., measured at the second position or re-measured at the first position) and the predetermined change in velocity to be obtained to drive the turbine (block  404 ). If, for example, the turbine is to be moved to the second position and the measured velocity range at the second position is different from the first position, the turbine components may be selected based on design properties associated with the water velocity range at the second position. The selected turbine components and/or the modular pieces of the components (or replacement components and/or the modular pieces of the components) are coupled to the turbine frame for continued operation of the turbine (block  406 ). Thus, the example method  400  provides for flexibility in constructing and operating the turbine, in that the common generator section can be adapted for use in different water velocity ranges without requiring a complete new turbine to be built. In the example method  400 , decoupling the turbine components and/or the modular pieces of the components (block  414 ) and coupling or recoupling the turbine components and/or the modular pieces of the components (block  402 ) can occur on site or proximate to the first position or the second position in the water. For example, the turbine can be removed from the water and the assembly and/or disassembly can occur on a barge. Therefore, rather than returning the turbine to shore or a factory, the example method  400  provides for efficient maintenance of the turbine via modular, lighter weight components as compared to integrally cast turbine components. 
     From the foregoing, it will be appreciated that the above disclosed methods and apparatus provide for hydrokinetic turbine construction based on modular components selectively coupled to a common generator frame or skeleton. The modular components, which include turbine intake sections and vanes, can be pre-fabricated with different design properties for specific water velocity ranges. Based on a water velocity range at a location in a body of water at which the turbine is to be installed, the modular components can be selected for coupling to the common generator section to build a turbine that efficiently operates based on the water velocity range at the location of installation. A plurality of turbines can be efficiently assembled and installed at a variety of locations in a body of water having different flow conditions and without having to build and/or assemble custom turbine components, which can be numerous and large. Instead, in the examples disclosed herein, modular components are selectively assembled to meet particular design characteristics at the respective locations of installation. Further, the selected components can be removed and replaced to account for changes in water properties without requiring a new generator section. Thus, the examples disclosed herein provide for an efficient, cost-effective approach to turbine construction in that the generator section is adaptable for operation in different water velocity ranges. Thus, the generator section can be reused in different installation locations instead of requiring the building of complete, individual turbines that are limited to specific water velocity ranges. 
     Although certain example methods, apparatus and articles of manufacture have been disclosed herein, the scope of coverage of this patent is not limited thereto. On the contrary, this patent covers all methods, apparatus and articles of manufacture fairly falling within the scope of the claims of this patent.