Water turbines with mixers and ejectors

A method of extracting energy from water traveling relative to a turbine system in an incoming current flow direction, the turbine system having an inlet end adapted to be directed into the incoming current flow direction and an outlet end opposite the inlet end, the water having a non-uniform flow velocity distribution across the inlet end of the turbine system, the method comprising:

• capturing a first volume of the water into a turbine shroud having a turbine shroud inner volume within which at least a portion of a rotor assembly is disposed, the rotor assembly being axially symmetric about an axis of rotation, the turbine shroud comprising a turbine shroud inlet disposed nearer the inlet end than the rotor assembly and a turbine shroud terminus disposed nearer the outlet end than the rotor assembly, the turbine shroud terminus comprising a plurality of turbine shroud mixer elements;
• directing the first volume of water through the rotor assembly such that the rotor assembly extracts energy from the first volume of water before the first volume of water at a lower energy is discharged from the turbine shroud via the turbine shroud terminus;
• capturing a second volume of the water into an ejector shroud disposed adjacent to the turbine shroud, the ejector shroud comprising an ejector shroud inlet and an ejector shroud terminus, the ejector shroud comprising an ejector shroud inlet and an ejector shroud terminus, the ejector shroud inlet having an asymmetrical cross-section along a plane passing through and perpendicular to the axis of rotation such that the ejector shroud inlet has a greater cross-sectional area on a lower velocity portion of the plane passing through the axis of rotation than on a higher velocity portion of the plane passing through the axis of rotation, the ejector shroud terminus extending in the incoming current flow direction beyond the turbine shroud mixer elements;
• and
• mixing the first and the second volumes of water into a mixed volume before discharge of the mixed volume from the ejector shroud terminus.

A turbine system for extracting energy from water traveling relative to the turbine system in an incoming current flow direction, the turbine system having an inlet end adapted to be directed into the incoming current flow direction and an outlet end opposite the inlet end, the water having a non-uniform flow velocity distribution across the inlet end of the turbine system, the turbine system comprising:

• a rotor assembly that is axially symmetric about an axis of rotation, the rotor assembly having an upstream rotor face oriented toward the inlet end;
• a turbine shroud having a turbine shroud inner volume within which at least a portion of the rotor assembly is disposed, the turbine shroud comprising a turbine shroud inlet disposed nearer the inlet end than the upstream rotor face and a turbine shroud terminus disposed nearer the outlet end than the rotor assembly, the turbine shroud terminus comprising a plurality of turbine shroud mixer elements, the turbine shroud mixer elements being asymmetric along a plane passing through and perpendicular to the axis of rotation such that at least one of the turbine shroud mixer elements on a lower velocity portion of the plane passing through the axis of rotation is larger than at least one of the turbine shroud mixer elements on a higher velocity portion of the plane passing through the axis of rotation, the turbine shroud inlet adapted to direct a first volume of water moving in the incoming current flow direction to the rotor assembly such that the first volume of water causes the rotor assembly to spin and to extract energy from the first volume of water before the first volume of water at a lower energy is discharged from the turbine shroud via the turbine shroud terminus;
• and
• an ejector shroud disposed adjacent to the turbine shroud, the ejector shroud comprising an ejector shroud inlet and an ejector shroud terminus extending in the incoming current flow direction beyond the turbine shroud mixer elements.