High efficiency impeller

1. An electric submersible pump (ESP) assembly comprising:

a pump having a plurality of stages, each stage comprising a rotatable impeller and a non-rotating diffuser;

a motor operatively coupled to the pump for rotating the impellers; wherein each of the impellers comprises:

a plurality of curved vanes interposed between an upper shroud and a lower shroud, each of the vanes curving radially outward from an area proximate to a cylindrical hub to an outer diameter of the lower shroud;

a plurality of parallel, spaced apart grooves formed in a convex surface of each of the vanes, each of the grooves extending substantially parallel with an elongate direction of the respective vane;

the plurality of parallel grooves comprising an upper groove and a lower groove, wherein each respective groove of the plurality of grooves defines a pair of ridges, one formed on the upper side of the respective groove and the other formed on the lower side of the respective groove; and

wherein the ridge on the upper side of the upper groove extends from the upper shroud, and the ridge on the lower side of the lower groove extends from the lower shroud.

2. The assembly of claim 1 , wherein:

each of the vanes has a high pressure side where the convex surface is located and a low pressure side opposite the high pressure side;

each of the vanes has a thickness measured between the high pressure side and the low pressure side of the vane that decreases from one of the shrouds to the other of the shrouds; and

one of the ridges has a greater height measured from the low pressure side to the high pressure side of the vane than the other ridges.

3. The assembly of claim 1 , wherein:

each of the grooves extends from an internal end of the vane proximate to the cylindrical hub toward a trailing end of the vane proximate to the outer diameter of the lower shroud;

the lower shroud defines a fluid inlet proximate to the cylindrical hub; and

rotation of the impeller in a first direction causes fluid to flow through the fluid inlet and along the convex surface of the vane.

4. The assembly of claim 1 , wherein:

each of the vanes has a high pressure side where the convex surface is located and a low pressure side opposite the high pressure side;

each of the vanes has a thickness measured between the high pressure side and the low pressure side of the vane that is greater at one of the shrouds than at the other of the shrouds; and

one of the grooves has a greater groove depth than the other of the grooves.

5. The impeller of claim 1 , wherein each of the grooves extends from an internal end of the vane to a predetermined location between the internal end of the vane and a trailing end of the vane.

6. An electric submersible pump (ESP) assembly comprising:

a pump having a plurality of stages for moving fluid, each of the stages comprising an impeller and a diffuser;

a motor operably coupled to the submersible pump for rotating the impellers in the pump;

each of the impellers positioned within the pump so that each of the impellers will accelerate fluid from a fluid inlet in the impellers toward an intake of a respective one of the diffusers of the pump, the impellers having a first shroud, a second shroud and a plurality of vanes interposed between the first shroud and the second shroud, the plurality of vanes extending radially outward from the fluid inlet to an outer diameter of the second shroud;

each of the vanes comprising:

an internal end at the fluid inlet and a trailing end at a periphery of the impeller;

a low pressure side and a high pressure side opposite the low pressure side and facing into a direction of rotation, the high pressure side having a convex curved surface;

a plurality of parallel, spaced apart grooves formed in the convex curved surface and extending parallel with a length of the vane, the plurality of parallel grooves comprising an upper groove and a lower groove, wherein each respective groove of the plurality of grooves defines a pair of ridges, one formed on the upper side of the respective groove and one formed on the lower side of the respective groove; and

wherein the ridge on the upper side of the upper groove extends from the first shroud, and the ridge on the lower side of the lower groove extends from the second shroud.

7. The assembly of claim 6 , wherein

one of the ridges has a greater height than the other ridges, each ridge being measured from the low pressure side to the high pressure side of the vane.

8. The assembly of claim 6 , wherein the plurality of grooves extend substantially a full length of the vane from the internal end of the vane proximate to the fluid inlet to the trailing end of the vane.

9. The assembly of claim 6 , wherein the plurality of grooves extend from the internal end of the vane proximate to the fluid inlet to a predetermined location between the internal end of the vane and the trailing end of the vane.

10. The assembly of claim 6 , wherein:

the ridges have rounded crests; and

the grooves have rounded valleys.