Mixed flow pump

• US 6,692,318 B2
• Filed: 06/07/2002
• Issued: 02/17/2004
• Est. Priority Date: 10/26/2001
• Status: Expired due to Fees

• Current Assignee: Penn State Research Foundation
• Original Assignee: Penn State Research Foundation
• Inventors: McBride, Mark W.
• Primary Examiner(s): AVILA, STEPHEN P
• Application Number:
  US10/165,128
• Publication Number:
  US 20030228214A1
• Time in Patent Office: 620 Days
• Field of Search: 440/38, 440/40, 440/42, 440/43, 440/47, 415/191, 415/192, 415/193, 415/199.1, 415/208.2, 415/211.2
• US Class Current: 440/38
• CPC Class Codes: B63H 11/08 of rotary type
• CPC Class Codes: B63H 23/24 electric dynamo-electric machines H02K
• CPC Class Codes: F04D 13/06 the pump being electrically driven
• CPC Class Codes: F04D 29/4273 suction eyes
• CPC Class Codes: F04D 29/448 bladed diffusers
• CPC Class Codes: F04D 3/00 Axial-flow pumps priming or boosting F04D9/00

Abstract

The present invention relates to propulsion and hydraulic systems having a co-axial design wherein the inlet section, impeller section, and outlet section of a mixed flow pump system all have a common centerline axis or axis of rotation. The mixed flow pump system includes an outer casing and a central body disposed co-axially within the outer casing. A pump impeller is rotatably connected to the central body for imparting hydraulic energy to the fluid flowing through the mixed flow pump system. The mixed flow pump system may also include inlet flow conditioning vanes for conditioning an inlet flow of fluid to the mixed flow impeller for improving the cavitation performance and/or acoustic performance of the pump module. Stator vanes are provided for connecting the central body to the outer casing and to remove any swirl velocity from the fluid flow exiting the mixed flow pump impeller. The mixed flow pump system exhibits improved resistance to cavitation due to the use of one or more of inlet flow conditioning vanes and low RPM motors for rotating the mixed flow pump impeller. The invention has applications in a variety of applications, including propulsion and hydraulic applications. For example, the invention may be used for the propulsion of marine vehicles, such as submerged crafts, weapons and unmanned underwater vehicles (UUVs) of various sizes and speed requirements. The mixed flow pump may also be applied to non-marine applications such as hydraulic applications, chemical distribution systems, and medical devices.

Claims

1. A co-axial mixed flow pump comprising:

an outer casing having a longitudinal centerline axis;

a central body aligned co-axially within said outer casing along said longitudinal centerline axis;

an axial forward looking inlet formed along said longitudinal centerline axis for receiving a flow of fluid;

a mixed flow pump having a rotating impeller mounted to a forward end of said central body, said mixed flow pump impeller comprising;

a hub;

a plurality of blades extending outward from said hub; and

a plurality of flow passages formed between adjacent blades,

wherein said mixed flow pump impeller rotates about said longitudinal centerline axis to draw a flow of fluid into said mixed flow pump impeller through said inlet and imparts energy to said fluid flow;

an annular passageway formed between said outer casing and said central body on a downstream side of said mixed flow impeller for receiving said fluid flow exiting said mixed flow impeller, said annular passageway being aligned axially;

a plurality of stator vanes disposed between and connecting said outer casing and said central body to condition said flow exiting said mixed flow pump impeller to flow generally in the axial direction;

an axial rearward looking outlet formed along said longitudinal centerline axis for discharging said flow of fluid from said mixed flow pump.

2. The mixed flow pump of claim 1, further comprising an inlet section extending forward of said axial forward looking inlet, said inlet section having a distal inlet opening at a forward end and a length of inlet ducting connecting said inlet opening to said mixed flow pump impeller.

3. The mixed flow pump of claim 2, wherein a forward portion of said inlet section further comprises a flush inlet.

4. The mixed flow pump of claim 1, further comprising a plurality of inlet flow conditioning vanes disposed in said inlet section to condition a fluid flow flowing into said mixed flow pump impeller, said inlet flow conditioning vanes connected at a first end to said inlet ducting and extending into said inlet ducting to a distal end.

5. The mixed flow pump of claim 4, wherein said inlet flow conditioning vanes comprise straight vanes attached to and extending radially inward from said outer casing to eliminate distortions of said fluid flow.

6. The mixed flow pump of claim 4, wherein said inlet flow conditioning vanes comprise curved vanes that are curved in the same direction as the direction of impeller rotation to impart swirl to the fluid flow entering said mixed flow pump impeller to reduce the relative velocity of the fluid flow to decrease cavitation and vibration noise.

7. The mixed flow pump of claim 4, wherein said inlet flow conditioning vanes comprise curved vanes that are curved into a direction of impeller rotation to impart swirl to the fluid flow entering said impeller and to increase the relative velocity of the fluid flow entering said mixed flow pump impeller to increase said mixed flow pump head rise potential.

8. The mixed flow pump of claim 4, wherein said inflow conditioning vanes extend radially into said inlet duct from said outer casing in a radial direction toward said centerline axis of said outer casing.

9. The mixed flow pump of claim 4, wherein said inlet flow conditioning vanes are leaned in a circumferential direction as said inlet flow conditioning vanes extend into said inlet duct.

10. The mixed flow pump of claim 4, further comprising a center member extending axially forward from said central body into said inlet section, wherein said inlet flow conditioning vanes are extend radially outward from said center member and are attached to said center member and said outer casing.

11. The mixed flow pump of claim 1, wherein said flow enters said mixed flow pump impeller axially, flows through said mixed flow impeller at an angle from said longitudinal centerline axis such that a pressure developed by said mixed flow pump is developed partly by centrifugal force and partly by a lift of said impeller blades on said fluid, and discharges said mixed flow pump impeller axially.

12. The mixed flow pump of claim 1, wherein said mixed flow pump impeller blades further comprise an open blade construction having a clearance gap formed between a distal end of said impeller blades and said outer casing blades.

13. The mixed flow pump of claim 1, wherein said mixed flow pump impeller blades further comprise a shrouded blade construction having a shroud disposed at a distal end of each of said impeller blades.

14. The mixed flow pump of claim 13, further comprising an embedded shrouded blade construction, wherein said shrouds of said shrouded impeller blades extend into and rotate within a groove in said outer casing.

15. The mixed flow pump of claim 1, wherein said drive motor is mounted axially rearward of said mixed flow impeller in said fluid flow.

16. The mixed flow pump of claim 1, wherein said plurality of stator vanes further comprise a curved wing-like shape for removing swirl velocity from said fluid flow exiting said mixed flow impeller and straightening said fluid flow to flow generally in the axial direction.

17. The mixed flow pump of claim 16, wherein said stator vanes are positioned at equal spacing around a circumference of said central body.

18. The mixed flow pump of claim 1, further comprising an inlet fairing that extends forward from a front end of said central body toward said inlet section and provides smooth flow into said impeller section and around said central body.

19. The mixed flow pump of claim 1, further comprising an outlet fairing that extends rearward from a rear end of said central body toward said outlet section, wherein said outlet fairing facilitates a smooth flow as said flow exits said annular passageway.

20. The mixed flow pump of claim 1, further comprising an outlet section having a forward end proximate said axial rearward looking outlet and a length of outlet ducting connecting said annular passageway to a discharge nozzle position in said outlet ducting proximal a discharge opening for accelerating said fluid flow as said fluid flow is discharged from said mixed flow pump.

21. A mixed flow pump for inputting hydraulic energy to a fluid flowing therethrough comprising:

an outer casing aligned axially from a forward end to a rearward end, said outer casing comprising an inlet section, an impeller section, and an outlet section;

said inlet section comprising;

an axially aligned inlet opening at said forward end;

an axially aligned inlet duct having a generally increasing cross-sectional area from a first end of said inlet duct proximal said inlet opening to a second end of said inlet duct;

said impeller section connected to a downstream end of said inlet section, said impeller section comprising;

an axially aligned impeller inlet connected to said second end of said inlet section;

an impeller sweep area having a generally increasing circular cross-sectional area from said impeller inlet to an impeller outlet;

said outlet section connected to a downstream end of said impeller section, said outlet section comprising;

an axially aligned inlet at a forward end of said outlet section connected to said impeller outlet;

an axially aligned outlet duct having a generally decreasing cross-sectional area from said outlet section inlet to a discharge;

a central body disposed within and co-axial with said outer casing, comprising;

a stationary hub disposed within said outlet section;

a mixed flow pump impeller rotatably mounted to a forward end of said hub and in said impeller section for drawing a flow of fluid through said inlet duct and into said mixed flow pump impeller;

an annular passageway formed between said central body and said outer casing and in said outlet section;

a stator blade assembly disposed between and connecting said central body and said outer casing to provide structural support for said central body, to remove any swirl velocity from said fluid flow exiting said mixed flow pump impeller, and to convert kinetic energy contained within the swirl velocity to pressure; and

a drive motor for rotating said mixed flow pump impeller.

22. The mixed flow pump of claim 21, further comprising inlet flow conditioning vanes disposed in said inlet section and extending into said inlet duct to condition said flow of fluid into said mixed flow pump impeller.

23. The mixed flow pump of claim 22, wherein said inlet flow conditioning vanes comprise curved vanes having a wing shape, wherein said curved vanes are oriented to curve or turn in the same direction as the direction of rotation of said mixed flow pump impeller thereby reducing the relative velocity of said fluid flow entering said mixed flow pump and reducing cavitation.

24. The mixed flow pump of claim 22, wherein said inlet flow conditioning vanes comprise curved vanes having a wing shape, wherein said curved vanes are oriented to curve or turn into the direction of rotation of said mixed flow pump impeller thereby increasing the relative velocity of said fluid flow entering said mixed flow pump and increasing the head rise potential of said mixed flow pump.

25. The mixed flow pump of claim 22, wherein said inlet flow conditioning vanes extend radially into said inlet duct from said outer casing toward said longitudinal centerline.

26. The mixed flow pump of claim 22, wherein said inlet flow conditioning vanes are leaned in a circumferential direction as they extend into said inlet duct.

27. A co-axial propulsion system comprising:

an outer casing comprising ducting having a longitudinal centerline, said ducting for containing and guiding a fluid flow within said co-axial propulsion system;

a forward looking, axial inlet opening of said outer casing centered about said longitudinal centerline for receiving an axial flow of fluid from one of an internal fluid system and an exterior fluid operating environment into an interior of said co-axial propulsion system;

a rearward looking, axial outlet opening of said outer casing centered about said longitudinal centerline for discharging an axial flow of fluid from said interior of said co-axial propulsion system to one of said internal fluid system and said exterior fluid operating environment;

wherein said ducting extends axially and connects said inlet opening and said outlet opening;

a central body disposed co-axially within said outer casing;

a mixed flow pump impeller rotatably mounted to said central body and disposed co-axially about said longitudinal centerline, wherein an axis of rotation of said mixed flow pump impeller is co-axial with said longitudinal centerline;

an annular passageway defined between said outer casing and said central body, said annular passageway being oriented co-axially about said longitudinal centerline;

a plurality of stator vanes disposed co-axially about said longitudinal centerline and extending radially between said outer casing and said central body and extending through said annular passageway, said stator vanes supporting said central body within said outer casing; and

wherein said stator vanes are configured to remove swirl velocity from said fluid flow exiting said mixed flow impeller and straightening said fluid flow to flow in an axial direction toward said outlet opening.

28. The co-axial propulsion system of claim 27, wherein said ducting further comprises inlet ducting formed between said inlet opening and said impeller section and a plurality of inlet flow conditioning vanes disposed in said inlet ducting for conditioning said fluid flow to improve one or more of cavitation performance and acoustic performance of said co-axial propulsion system.

29. The co-axial propulsion system of claim 27, further comprises outlet ducting and a discharge nozzle for discharging said fluid flow from said ducting to produce thrust, wherein said outlet ducting is formed between said impeller section and said outlet opening and wherein said plurality of stator vanes are disposed in said outlet ducting.

30. A co-axial mixed flow pump system comprising:

an outer casing axially aligned about a centerline axis;

a central body disposed within said outer casing and aligned about said centerline axis;

a mixed flow pump rotatably mounted to a front end of said central body and having an axis of rotation that is coincident with said centerline axis;

a plurality of stator vanes disposed between and connecting said outer casing and said central body for removing swirl velocity from a flow exiting said mixed flow pump and causing said exiting flow to flow in an axial direction;

an internal flow passage defined by said outer casing, wherein said internal flow passage further comprising;

an axially inlet flow passage;

an axial inlet to said mixed flow pump;

an axial discharge from said mixed flow pump;

an axially aligned annular flow passage defined between said outer casing and said central body; and

an axially aligned outlet flow passage.