Hydroelectric/hydrokinetic turbine and methods for making and using same

A method for designing a unidirectional hydrokinetic turbine having a water entrance end and a water exit end, defining a direction of water flow through the turbine, comprising:

• selecting a generally cylindrical accelerator shroud that has a wall cross-section that comprises an initial asymmetrical hydrofoil shape and defines within its cylindrical cross-section a flow area, where the hydrofoil shape is selected based on fluid dynamics principles to serve to accelerate the flow of water through the accelerator shroud and to create a negative pressure field behind the accelerator shroud, in the direction of water flow;
• designing a rotor assembly that is mounted for rotation within the accelerator shroud around an axis that is generally parallel to the direction of water flow through the turbine, the rotor assembly comprising (i) a generally elongated cylindrical center hub having and a wall cross-section comprising an initial hydrofoil shape that is selected based on fluid dynamics principles;
• (ii) a plurality of rotor blades fixed to and extending radially outwardly from the center hub wall for rotation therewith and terminating at rotor tips, which blades have an initial asymmetrical hydrofoil-shaped cross-sectional configuration that is selected based on fluid dynamics principles;
• and (iii) a rotor outer ring to which the blade tips are attached and having an outer circumference which is configured for rotation within the accelerator shroud;
• designing an annular diffuser comprising a generally cylindrical ring member that has a wall cross-section comprising an initial asymmetrical hydrofoil shape that is selected based on fluid dynamics principles, wherein the annular diffuser has a diameter greater than the diameter of the accelerator shroud and is configured to be positioned behind the main accelerator shroud, in the direction of water flow through the turbine, preferably in overlapping relationship;
• and
• modifying the initial hydrofoil shapes of the annular accelerator, the center hub, the rotor blades and the annular diffuser, in response to CFD testing of a turbine design comprising such components, in such a way as to provide final hydrofoil shapes for all of these components that (a) at least enhance the ability to accelerate the flow of water through the annular diffuser and to create a negative pressure field behind the annular diffuser, and (b) provide cooperation between the final hydrofoil shapes of the accelerator shroud, the rotor hub and the blades to at least enhance acceleration of water flow through the accelerator shroud at the location of the rotor assembly.

A unidirectional hydrokinetic turbine having a water entrance end and a water exit end defining a direction of water flow through the turbine, comprising:

• a generally cylindrical accelerator shroud that has a wall cross-section that comprises an asymmetrical hydrofoil shape and defines within its cylindrical cross-section a flow area, said hydrofoil shape serving to accelerate the flow of water through the accelerator shroud and to create a negative pressure field behind the accelerator shroud, in the direction of water flow;
• a rotor assembly that is mounted for rotation within the main accelerator shroud around an axis that is generally parallel to the direction of water flow through the turbine, the rotor assembly comprising:
• a plurality of rotor blades extending radially outwardly from an open center of the turbine and terminating at rotor blade tips, which blades have an asymmetrical hydrofoil-shaped cross-sectional configuration;
• and a rotor outer ring to which the blade tips are directly attached, and the outer ring being configured to support the rotor assembly within the accelerator shroud and having a radially outer circumference which is configured for rotation within said accelerator shroud wall cross-section;
• and
• a first annular diffuser comprising, a generally cylindrical ring member that has a wall cross-section comprising an asymmetrical hydrofoil shape, said annular diffuser having a diameter greater than the diameter of said accelerator shroud, being radially spaced from said accelerator shroud, and being positioned behind the main accelerator shroud, in the direction of water flow through the turbine, whereby the hydrofoil shape of the annular diffuser serves to accelerate the flow of water through the annular diffuser and to create a negative pressure field behind the annular diffuser, and in cooperation with the hydrofoil of said accelerator shroud, said rotor hub and said blades to augment acceleration of water flow through the main accelerator shroud at the location of the rotor assembly.