Pump and reversible pump-turbine

An apparatus that imparts work to a fluid and redirects said fluid, said apparatus comprising:

• an impeller having an impeller inlet through which said fluid flows as an impeller inflow in a first direction in a meridional plane through said apparatus;
• blades of said impeller that are established downflow of said impeller inlet, that define an impeller axis of rotation, and that are configured to contact and redirect said impeller inflow along a toroidal flowpath to generate an impeller discharge that has both an axial velocity component and a tangential velocity component;
• wherein said axial velocity component is substantially 180 degrees relative to said first direction of said impeller inflow, in said meridional plane,
• said apparatus further comprising a diffuser that is established around a diffuser axis that is aligned with said impeller axis of rotation, said diffuser having a diffuser inlet through which a diffuser inflow flows and having a diffuser-inlet flow area and a diffuser outlet through which a diffuser outflow flows and having a diffuser-outlet flow area, wherein said diffuser-outlet flow area is greater than said diffuser-inlet flow area.

A pump-turbine comprising:

• a runner defining a runner axis of rotation and having runner blades configured to contact and redirect fluid along a toroidal flowpath, said runner having a first runner opening through which said fluid enters said runner when said pump-turbine is in pump mode, and from which said fluid exits said runner when said pump-turbine is in turbine mode, and said runner having a second runner opening through which said fluid enters said runner when said pump-turbine is in turbine mode, and from which said fluid exits said runner when said pump-turbine is in pump mode, wherein said toroidal flowpath reverses flow between said two runner openings substantially 180 degrees;
• a diffuser vane-guide vane component that defines and is established around a diffuser vane-guide component axis that is aligned with said runner axis of rotation, wherein said diffuser vane-guide vane component has a first annular opening that is established substantially at said second runner opening, through which fluid enters said diffuser vane-guide vane component when said pump-turbine is in pump mode and from which fluid exits said diffuser vane-guide vane component when said pump-turbine is in turbine mode, and a second annular opening established further from said runner than is said first annular opening, through which fluid enters said diffuser vane-guide vane component when said pump-turbine is in turbine mode and from which fluid exits said diffuser vane-guide vane component when said pump-turbine is in pump mode,
• wherein said first annular opening has a first-annular-opening flow area, said second annular opening has a second-annular-opening flow area, and said second-annular-opening flow area is greater than said first-annular-opening flow area, and
• wherein terminal portions of vanes of said diffuser vane-guide vane component that are substantially at said first annular opening are canted in a tangential direction and terminal portions of said vanes that are substantially at said second annular opening are substantially along radial extensions from said diffuser vane-guide vane component axis.