EP2614257A1 - Pumping element design - Google Patents
Pumping element designInfo
- Publication number
- EP2614257A1 EP2614257A1 EP10755047.7A EP10755047A EP2614257A1 EP 2614257 A1 EP2614257 A1 EP 2614257A1 EP 10755047 A EP10755047 A EP 10755047A EP 2614257 A1 EP2614257 A1 EP 2614257A1
- Authority
- EP
- European Patent Office
- Prior art keywords
- blade
- pumping element
- section
- incidence angle
- tip
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Withdrawn
Links
Classifications
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01D—NON-POSITIVE DISPLACEMENT MACHINES OR ENGINES, e.g. STEAM TURBINES
- F01D5/00—Blades; Blade-carrying members; Heating, heat-insulating, cooling or antivibration means on the blades or the members
- F01D5/12—Blades
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
- F04D—NON-POSITIVE-DISPLACEMENT PUMPS
- F04D29/00—Details, component parts, or accessories
- F04D29/18—Rotors
- F04D29/22—Rotors specially for centrifugal pumps
- F04D29/2261—Rotors specially for centrifugal pumps with special measures
- F04D29/2277—Rotors specially for centrifugal pumps with special measures for increasing NPSH or dealing with liquids near boiling-point
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
- F04D—NON-POSITIVE-DISPLACEMENT PUMPS
- F04D29/00—Details, component parts, or accessories
- F04D29/18—Rotors
- F04D29/22—Rotors specially for centrifugal pumps
- F04D29/24—Vanes
- F04D29/242—Geometry, shape
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
- F04D—NON-POSITIVE-DISPLACEMENT PUMPS
- F04D29/00—Details, component parts, or accessories
- F04D29/66—Combating cavitation, whirls, noise, vibration or the like; Balancing
- F04D29/669—Combating cavitation, whirls, noise, vibration or the like; Balancing especially adapted for liquid pumps
Definitions
- the present disclosure relates to a pumping element, and more particularly to design methodology therefor.
- Fluid pumps include axial flow pumps and centrifugal flow pumps.
- Historical design practice typically achieves the required suction performance with some cavitation induced instability.
- Typical historical design practices such as increased tip clearance, casing treatment, and tip vortex suppression have limited success to minimize cavitation induced instability but often result in reduced suction performance capability.
- Figure 1 is a developed view of a blade leading edge
- Figure 2 is a RELATED ART graphical representation of the pumping element design throat thickness and cavity height
- Figure 3 is a graphical representation of a pumping element leading edge design approach according to one non-limiting embodiment of the present application.
- FIG. 1 there is shown a schematic view of a blade 20 of a pumping element, inducer, and impeller. Cavitation occurs on pump elements when the static pressure is decreased to a value below that of the fluid vapor pressure. Many types of cavitation are known to occur in fluid mechanics.
- Equation 1 The flow coefficient ⁇ shown in Equation 1 defines the relationship between the inlet meridonal velocity C m , the blade speed U, blade angle ⁇ , and incidence angle .
- the design philosophy disclosed herein constrains the value of blade angle ⁇ as a function of incidence angle to essentially render the incidence angle an independent variable as opposed to the conventional process which considers incidence angle as a dependent variable.
- the information given in Stripling (1962), Japikse (2001), and Hashimoto (1997) is representative of conventional design practice for selection of blade angle ⁇ and incidence angle . Included by reference herein.
- the conventional pump element design methodology typically uses a positive tip incidence angle. For an un-shrouded pumping element, this positive tip incidence angle combined with the tip clearance generates a tip vortex which can travel upstream of the pumping element. This upstream flow is often called backflow.
- the backflow strength and flowrate are determined by tip incidence angle and the tip clearance. As the backflow strength and flowrate reach a certain level, the backflow will interact with the adjacent pumping element blade and cavitation instabilities will be generated.
- the cavitation instability mode shapes are determined by the complicity of the backflow and adjacent blade interactions.
- the pumping element maximum throat blade thickness from hub-to-tip is usually a linear function of radius ( Figure 2).
- the minimum and maximum blade thicknesses are determined by structural requirements.
- the conventional pumping element design process defines the blade leading edge angle by holding the radius (r) times the tangent of the blade angle ( ⁇ ) equal to a constant. This design approach results in the cavity volume being substantial greater than the blade volume ( Figure 2). This results in cavitation induced instabilities. To fix this shortcoming, alternative blade leading edge angle distributions are required.
- a pumping element includes a blade having a first section proximate a hub and a second section proximate a tip.
- a cavity height distribution is based on a selected incidence angle distribution.
- a selected blade thickness distribution is based on a structural requirement.
- the resulting cavity height distribution matches the blade thickness at the first section and the second section and is greater than the blade thickness along the blade. That is, the incidence angle at the hub ( ⁇ 3 ⁇ 4) and tip ( ⁇ 3 ⁇ 4) are chosen to match the cavity heights with the first section hub and second section tip blade thicknesses.
- the cavity volume is substantial less than the conventional pumping element cavity volume and much closer to the blade volume.
- the reduction in cavity volume results in the reduction of cavitation pumping element instabilities. Additionally, this approach achieved excellent suction performance.
Landscapes
- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Physics & Mathematics (AREA)
- Geometry (AREA)
- Structures Of Non-Positive Displacement Pumps (AREA)
Abstract
A pumping element includes a blade (20) having a first section proximate a hub and a second section proximate a tip, a cavity height distribution based on a selected incidence angle distribution and a selected blade thickness distribution based on a structural requirement. The resulting cavity height distribution matches the blade thickness at the first section and the second section and is greater than the blade thickness along the blade.
Description
PUMPING ELEMENT DESIGN
BACKGROUND
The present disclosure relates to a pumping element, and more particularly to design methodology therefor.
Fluid pumps include axial flow pumps and centrifugal flow pumps. Historical design practice typically achieves the required suction performance with some cavitation induced instability. Typical historical design practices such as increased tip clearance, casing treatment, and tip vortex suppression have limited success to minimize cavitation induced instability but often result in reduced suction performance capability.
BRIEF DESCRIPTION OF THE DRAWING
Various features will become apparent to those skilled in the art from the following detailed description of the disclosed non-limiting embodiment. The drawings that accompany the detailed description can be briefly described as follows:
Figure 1 is a developed view of a blade leading edge;
Figure 2 is a RELATED ART graphical representation of the pumping element design throat thickness and cavity height; and
Figure 3 is a graphical representation of a pumping element leading edge design approach according to one non-limiting embodiment of the present application.
DETAILED DESCRIPTION
Referring to Figure 1, there is shown a schematic view of a blade 20 of a pumping element, inducer, and impeller. Cavitation occurs on pump elements when the static pressure is decreased to a value below that of the fluid vapor pressure. Many types of cavitation are known to occur in fluid mechanics.
The flow coefficient φ shown in Equation 1 defines the relationship between the inlet meridonal velocity Cm , the blade speed U, blade angle β, and incidence angle . 0 = ^ = tm(B - ) l
U
The design philosophy disclosed herein constrains the value of blade angle β as a function of incidence angle to essentially render the incidence angle an independent variable as opposed to the conventional process which considers incidence angle as a dependent variable. The information given in Stripling (1962), Japikse (2001), and Hashimoto (1997) is representative of conventional design practice for selection of blade angle β and incidence angle . Included by reference herein.
The conventional pump element design methodology typically uses a positive tip incidence angle. For an un-shrouded pumping element, this positive tip incidence angle combined with the tip clearance generates a tip vortex which can travel upstream of the pumping element. This upstream flow is often called backflow. The backflow strength and flowrate are determined by tip incidence angle and the tip clearance. As the backflow strength and flowrate reach a certain level, the backflow will interact with the adjacent pumping element blade and cavitation instabilities will be generated. The cavitation instability mode shapes are determined by the complicity of the backflow and adjacent blade interactions.
The pumping element maximum throat blade thickness from hub-to-tip is usually a linear function of radius (Figure 2). The minimum and maximum blade thicknesses are determined by structural requirements. The conventional pumping element design process defines the blade leading edge angle by holding the radius (r) times the tangent of the blade angle (β) equal to a constant. This design approach results in the cavity volume being substantial greater than the
blade volume (Figure 2). This results in cavitation induced instabilities. To fix this shortcoming, alternative blade leading edge angle distributions are required.
The new approach to defining the blade leading edge angle distribution requires that the pumping element leading edge blade angle and resulting incidence angle are tailored (Figure 3). A pumping element includes a blade having a first section proximate a hub and a second section proximate a tip. A cavity height distribution is based on a selected incidence angle distribution. A selected blade thickness distribution is based on a structural requirement. The resulting cavity height distribution matches the blade thickness at the first section and the second section and is greater than the blade thickness along the blade. That is, the incidence angle at the hub (<¾) and tip (<¾) are chosen to match the cavity heights with the first section hub and second section tip blade thicknesses.
With this approach, the cavity volume is substantial less than the conventional pumping element cavity volume and much closer to the blade volume. The reduction in cavity volume results in the reduction of cavitation pumping element instabilities. Additionally, this approach achieved excellent suction performance.
Claims
What is claimed is:
1. A pumping element comprising:
a blade having a first section proximate a hub, a second section proximate a tip;
a selected incidence angle distribution;
a selected blade thickness distribution based on a structural requirement; and
a cavity height distribution based on the selected incidence angle distribution, wherein the resulting cavity height distribution matches the blade thickness at the first section and the second section and is greater than the blade thickness along the blade.
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
PCT/US2010/048332 WO2012033495A1 (en) | 2010-09-10 | 2010-09-10 | Pumping element design |
Publications (1)
Publication Number | Publication Date |
---|---|
EP2614257A1 true EP2614257A1 (en) | 2013-07-17 |
Family
ID=43982215
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP10755047.7A Withdrawn EP2614257A1 (en) | 2010-09-10 | 2010-09-10 | Pumping element design |
Country Status (5)
Country | Link |
---|---|
US (1) | US20130170974A1 (en) |
EP (1) | EP2614257A1 (en) |
JP (1) | JP5684390B2 (en) |
CN (1) | CN103080561B (en) |
WO (1) | WO2012033495A1 (en) |
Family Cites Families (9)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3442220A (en) * | 1968-08-06 | 1969-05-06 | Rolls Royce | Rotary pump |
JPH0772529B2 (en) * | 1988-06-20 | 1995-08-02 | 株式会社日立製作所 | Water turbine and its manufacturing method |
CN1017271B (en) * | 1988-11-09 | 1992-07-01 | 株式会社日立制作所 | Water turbine |
JP2969321B2 (en) * | 1994-03-04 | 1999-11-02 | 株式会社クボタ | Axial flow pump |
JPH11247788A (en) * | 1998-02-27 | 1999-09-14 | Shin Meiwa Ind Co Ltd | Axial flow pump and aeration device having the same |
US6435829B1 (en) * | 2000-02-03 | 2002-08-20 | The Boeing Company | High suction performance and low cost inducer design blade geometry |
WO2004007970A1 (en) * | 2002-07-12 | 2004-01-22 | Ebara Corporation | Inducer, and inducer-equipped pump |
US7097414B2 (en) * | 2003-12-16 | 2006-08-29 | Pratt & Whitney Rocketdyne, Inc. | Inducer tip vortex suppressor |
JP3949663B2 (en) * | 2004-01-29 | 2007-07-25 | 三相電機株式会社 | Centrifugal impeller |
-
2010
- 2010-09-10 US US13/821,014 patent/US20130170974A1/en not_active Abandoned
- 2010-09-10 EP EP10755047.7A patent/EP2614257A1/en not_active Withdrawn
- 2010-09-10 WO PCT/US2010/048332 patent/WO2012033495A1/en active Application Filing
- 2010-09-10 JP JP2013528174A patent/JP5684390B2/en active Active
- 2010-09-10 CN CN201080069026.1A patent/CN103080561B/en active Active
Non-Patent Citations (2)
Title |
---|
None * |
See also references of WO2012033495A1 * |
Also Published As
Publication number | Publication date |
---|---|
CN103080561B (en) | 2016-06-15 |
JP2013537274A (en) | 2013-09-30 |
US20130170974A1 (en) | 2013-07-04 |
CN103080561A (en) | 2013-05-01 |
WO2012033495A1 (en) | 2012-03-15 |
JP5684390B2 (en) | 2015-03-11 |
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Legal Events
Date | Code | Title | Description |
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PUAI | Public reference made under article 153(3) epc to a published international application that has entered the european phase |
Free format text: ORIGINAL CODE: 0009012 |
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17P | Request for examination filed |
Effective date: 20130301 |
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AK | Designated contracting states |
Kind code of ref document: A1 Designated state(s): AL AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HR HU IE IS IT LI LT LU LV MC MK MT NL NO PL PT RO SE SI SK SM TR |
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DAX | Request for extension of the european patent (deleted) | ||
RAP1 | Party data changed (applicant data changed or rights of an application transferred) |
Owner name: AEROJET ROCKETDYNE OF DE, INC. |
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17Q | First examination report despatched |
Effective date: 20170213 |
|
STAA | Information on the status of an ep patent application or granted ep patent |
Free format text: STATUS: THE APPLICATION IS DEEMED TO BE WITHDRAWN |
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18D | Application deemed to be withdrawn |
Effective date: 20170624 |