Electric submersible pump rotor assembly with hydrodynamic bearing
An exemplary rotor assembly for an electric submersible pump may include a drive shaft, a journal sleeve concentrically disposed about and rotationally fixed to the drive shaft, a bushing concentrically disposed about and configured to rotate with respect to the journal sleeve, and a thrust washer, or component integrating the thrust washer, encircling the drive shaft. Concavities may be formed in an axial face of the bushing or an axial face of the thrust washer. The axial face of the bushing may be disposed proximate to the axial face of the thrust washer. The concavities may be configured to influence flow of lubrication fluid between the bushing and the thrust washer to create a hydrodynamic force against the bushing and the thrust washer when the drive shaft rotates to prevent axial contact.
1 . A rotor assembly for an electric submersible pump, comprising:
a drive shaft;
a journal sleeve concentrically disposed about and rotationally fixed to the drive shaft;
a bushing concentrically disposed about the journal sleeve; and
a thrust washer encircling the drive shaft,
wherein concavities are formed in an axial face of the bushing or an axial face of the thrust washer,
wherein the axial face of the bushing is disposed proximate to the axial face of the thrust washer,
wherein each of the concavities has an arc radius and a depth,
wherein the arc radius is greater than 5,000 times the depth, and
wherein the concavities are configured to influence flow of lubrication fluid between the bushing and the thrust washer to create a hydrodynamic force against the bushing and the thrust washer when the drive shaft rotates.
2 . The rotor assembly of claim 1 , wherein grooves are formed in the axial face of the bushing or the axial face of the thrust washer, and wherein the grooves are configured to guide lubrication fluid radially outward.
3 . The rotor assembly of claim 1 , wherein the hydrodynamic force prevents contact between the bushing and the thrust washer when the drive shaft rotates.
4 . The rotor assembly of claim 2 , wherein the grooves extend deeper than the concavities, and wherein the grooves are formed in the concavities or between the concavities.
5 . The rotor assembly of claim 1 , wherein the concavities comprise an arcuate profile or a chamfer.
6 . The rotor assembly of claim 1 , wherein an angle of a profile of the concavities with respect to the axial face of the bushing or the axial face of the thrust washer is less than 10 degrees.
7 . The rotor assembly of claim 1 , wherein the depth of the concavities is less than 0.2 mm, and the radius of the concavities is greater than 200 mm.
8 . The rotor assembly of claim 1 , wherein the hydrodynamic force is 5 to 5,000 N.
9 . An electric submersible pump for pumping fluid in a wellbore, comprising:
a centrifugal pump;
a drive shaft configured to transmit torque to the centrifugal pump;
a journal sleeve concentrically disposed about and rotationally fixed to the drive shaft;
a bushing concentrically disposed about the journal sleeve;
a stator concentrically disposed about the bushing; and
a thrust washer encircling the drive shaft,
wherein concavities are formed in an axial face of the bushing or an axial face of the thrust washer,
wherein the axial face of the bushing is disposed proximate to the axial face of the thrust washer,
wherein a depth of the concavities is less than 0.2 mm,
wherein a radius of the concavities is greater than 200 mm, and
wherein the concavities are configured to influence flow of lubrication fluid between the bushing and the thrust washer to create a hydrodynamic film between the bushing and the thrust washer when the drive shaft rotates.
10 . The electric submersible pump of claim 9 , wherein the drive shaft is oriented in the wellbore vertically.
11 . The electric submersible pump of claim 9 , wherein a first slot is formed in an outer circumferential surface of the bushing proximate to the axial face of the bushing, a second slot is formed in the outer circumferential surface of the bushing proximate to another axial face of the bushing, and wherein an anti-rotation tab is secured in a longitudinal slit in the outer circumferential surface of the bushing by a first retention ring disposed in the first slot and a second retention ring disposed in the second slot.
12 . The electric submersible pump of claim 11 , wherein the anti-rotation tab is inserted inside a slot in the stator.
13 . The electric submersible pump of claim 9 , wherein each of the concavities has an arc radius and a depth, and wherein the arc radius is greater than 5,000 times the depth.
14 . The electric submersible pump of claim 9 , wherein a hydrodynamic force against the bushing and the thrust washer is 5 to 5,000 N when the drive shaft rotates.
15 . The electric submersible pump of claim 14 , wherein the hydrodynamic force prevents contact between the bushing and the thrust washer when the drive shaft rotates.
16 . The electric submersible pump of claim 9 , wherein grooves are formed in the axial face of the bushing or the axial face of the thrust washer, and wherein the grooves are configured to guide lubrication fluid radially outward.
17 . A rotor assembly for an electric submersible pump, comprising:
a drive shaft;
a journal sleeve concentrically disposed about and rotationally fixed to the drive shaft;
a bushing concentrically disposed about the journal sleeve; and
a component encircling the drive shaft,
wherein concavities are formed in an axial face of the bushing or an axial face of the component,
wherein the axial face of the bushing is disposed proximate to the axial face of the component, and
wherein the concavities are configured to influence flow of lubrication fluid between the bushing and the component to create a hydrodynamic force of 5 to 5,000 N against the bushing and the component when the drive shaft rotates.
18 . The rotor assembly of claim 17 , wherein grooves are formed in the axial face of the bushing or the axial face of the component, and wherein the grooves are configured to guide lubrication fluid radially outward.
19 . The rotor assembly of claim 17 , wherein the component is a rotor module configured to act as a thrust washer.
20 . The rotor assembly of claim 17 , wherein each of the concavities has an arc radius and a depth, and wherein the arc radius is greater than 5,000 times the depth.
21 . The rotor assembly of claim 17 , wherein the hydrodynamic force is 5 to 5,000 N.
22 . The rotor assembly of claim 17 , wherein grooves are formed in the concavities or between the concavities, and wherein the grooves extend deeper than the concavities.
23 . The rotor assembly of claim 17 , wherein the concavities comprise an arcuate profile or a chamfer.