CN105443433A - Design method for cavitation-resistance axial flow pump impeller - Google Patents
Design method for cavitation-resistance axial flow pump impeller Download PDFInfo
- Publication number
- CN105443433A CN105443433A CN201510908837.0A CN201510908837A CN105443433A CN 105443433 A CN105443433 A CN 105443433A CN 201510908837 A CN201510908837 A CN 201510908837A CN 105443433 A CN105443433 A CN 105443433A
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- China
- Prior art keywords
- cavitation
- impeller
- flow pump
- blade
- pump impeller
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Classifications
-
- 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
- F04D29/181—Axial flow rotors
-
- 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
- F04D29/661—Combating cavitation, whirls, noise, vibration or the like; Balancing especially adapted for elastic fluid pumps
- F04D29/666—Combating cavitation, whirls, noise, vibration or the like; Balancing especially adapted for elastic fluid pumps by means of rotor construction or layout, e.g. unequal distribution of blades or vanes
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F05—INDEXING SCHEMES RELATING TO ENGINES OR PUMPS IN VARIOUS SUBCLASSES OF CLASSES F01-F04
- F05D—INDEXING SCHEME FOR ASPECTS RELATING TO NON-POSITIVE-DISPLACEMENT MACHINES OR ENGINES, GAS-TURBINES OR JET-PROPULSION PLANTS
- F05D2240/00—Components
- F05D2240/20—Rotors
- F05D2240/30—Characteristics of rotor blades, i.e. of any element transforming dynamic fluid energy to or from rotational energy and being attached to a rotor
- F05D2240/301—Cross-sectional characteristics
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- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Structures Of Non-Positive Displacement Pumps (AREA)
Abstract
The invention relates to the field of hydraulic design of axial flow pumps, in particular to a design method for a cavitation-resistance axial flow pump impeller. In the step of calculating a streamline of a pressure surface of a blade, the specific value of the distance 1 between the largest section thickness of an impeller wing section to a wing section head and the wing section chord length L on the section is 60%-69%. By means of the scheme, the designed axial flow pump impeller can have extremely high cavitation-resistance capability under the condition that normal and reliable work is ensured.
Description
Technical field
The present invention relates to axial-flow pump the Hydraulic Design field, particularly a kind of anti-cavitation axial-flow pump impeller design method.
Background technique
Cavitation, when referring to that in liquid, local compression is reduced to below Critical Cavitation Coefficient pressure, the formation in the hole (cavity) of steam or gas on liquid internal or liquid-solid interface, the phenomenon that develops and crumble and fall.Cavitation phenomenon be axial-flow pump the Hydraulic Design and use time all should do one's utmost to avoid; But the cavitation situation of axial-flow pump when practical application but frequently occurs.Once cavitation phenomenon occurs, time serious, impeller cavitation corrosion can occur, destroy hydraulic part, pump hydraulic performance declines, and even causes pump assembly cannot normally work at all.For overcoming above-mentioned cavitation phenomenon, in the industry for the treatment measures of axial-flow pump impeller, embodying a concentrated expression of in the later stage modification to blade wheel structure, also namely secondary operations being carried out to the impeller after completing or adding extension.Notification number is the patent name of CN1414248 is in the patent of invention of " axial flow pump impeller vane ", propose and have employed at end of blade and leaf root part the impeller blade lengthening the distorted shape leaned forward, impeller blade can control shell and the development in ring-type boundary layer on hub surface and being separated of blade suction surface top interlayer effectively, reduce blade tip load simultaneously, reduce the impact of Clearance Flow, thus reach the effect reducing cavitation phenomenon and occur.Then open in the utility application that to be the patent name of CN204610363U be notification number " a kind of suppress the axial-flow pump of vacuum side of blade cloud cavitation ": wide apart from water inlet limit 75%C place welding one at the axial flow pump blade inner back side is 3%C, height is the blend stop of 2%C, to reach the effect hindering retroeflection stream, change to cloud cavitation to suppress sheet cavitation comparatively stable on the axial flow pump blade inner back side.Above-mentioned two kinds of modes are use more later stage modification measure at present.But it should be noted that axial-flow pump is as one application high-specific rotation speed vane pump very widely, it has been tending towards when initial designs perfectly take into account the impact of liquid stream; No doubt the cavitation situation of impeller is improved to a certain extent by later stage modification, but artificially on original perfect runner with the addition of the projective structures such as such as blend stop, the integrity of original design runner will inevitably be destroyed, and the normal high speed circulation of liquid medium is had an impact, cause hydraulic loss, pump hydraulic performance is declined, once processing is not good at reaching the object improving cavitation on the contrary.
Summary of the invention
The object of this invention is to provide a kind of anti-cavitation axial-flow pump impeller design method, which overcome traditional design chains, original base of design provides brand-new parameter designing mode, thus make the axial-flow pump impeller designed while normal reliable work, extremely strong anti-cavitation ability can be possessed in guarantee.
For achieving the above object, present invention employs following technological scheme:
A kind of anti-cavitation axial-flow pump impeller design method, it is characterized in that: in blade pressure surface calculation of streamlines step, the ratio getting aerofoil profile chord length L in thickness place, impeller aerofoil profile maximum cross-section to wing type head distance l and this cross section is 60% ~ 69%.
Major advantage of the present invention is:
1), the anti-cavitation operation of current axial-flow pump impeller has been broken by means of only later stage constructional variant measure, and the initial design runner of the destruction caused and affect the intrinsic defect of pump housing hydraulic performance.The present invention traces to source, seeking breakthrough from initial and the most perfect initial design.Claimant is found by mass data and demonstration, lift method, arc method and singular point distribution etc. are adopted because current axial flow pump blade inner design is normal, these design method are all carry out calculating design to blade pressure surface streamline to obtain, and blade suction surface streamline is then thicken according to American National aviation office NACA series aerofoil sections or 971 aerofoil profiles directly to obtain.These thickness places, aerofoil profile maximum cross-section are 40% ~ 50% of aerofoil profile chord length L on this cross section to wing type head distance l.For ease of expressing definition φ=l/L, so φ=0.4 ~ 0.5.And just because of above-mentioned ratio, impeller maximum ga(u)ge place is offset to impeller influent side, due to impeller from influent side to water outlet side change procedure hydraulic pressure increase gradually, and influent side fluid pressure is relatively low, liquid medium is caused very easily to produce flow separation phenomenon near blade suction surface maximum ga(u)ge, form whirlpool, and then cavitation phenomenon occurs.
Instant invention overcomes the usual thinking chains of people for many years, by the value of employing φ=0.60 ~ 0.69 looked for another way, thus reach the object of adjustment blade suction surface streamline distribution.After the adjustment of blade suction surface streamline distribution, maximum blade thickness place starts to move to liquid medium Way out, and then moves after making fluid flow separation point.From axial-flow pump impeller sheet acting principle: from vane inlet to outlet change procedure, the energy that fluid obtains increases gradually, the pressure of flow separation zone will be improved like this, make pressure in separated region higher than liquid cavitation pressure, reach the object improving pump cavitation performance.Through testing and verification, present invention achieves the anti-cavitation effect before axial-flow pump impeller manufacture, it is without the need to carrying out later stage constructional variant, can not destroy the continuity of current traditional procedure simultaneously, the integrity of runner that medium is advanced for liquid is also preserved, the anti-cavitation excellent of pump.
Accompanying drawing explanation
Impeller blade aerofoil section structural drawing when Fig. 1 is traditional design;
Fig. 2 for the present invention design after impeller blade aerofoil section structural drawing;
When Fig. 3 is for employing traditional φ value, pump cavitation performance chart during φ=0.4;
When Fig. 4 is for employing φ value of the present invention, pump cavitation performance chart during φ=0.6;
When Fig. 5 is for employing φ value of the present invention, pump cavitation performance chart during φ=0.69.
Embodiment
Traditional axial-flow pump impeller design procedure utilizes following key parameter to realize purpose of design substantially, mainly comprises:
Impeller outer diameter D, hub diameter d
h, aerofoil profile laying angle β
m, maximum blade thickness δ
max, cascade solidity L/t, the ratio psi etc. of aerofoil profile chord length L in aerofoil profile maximum ga(u)ge place to wing type head distance l and this cross section.
The determination of impeller outer profile physical dimension:
1), according to actual needs, adopt Similar, determine impeller outer diameter D;
2), according to controlling mechanism physical dimension, and the intensity of joining material, consider, select suitable hub ratio d
h/ D, general warranty d
h/ D=0.30 ~ 0.55.Comprise wheel hub, blade, interior, is divided into 3 ~ 5 streamiline surfaces by wheel rim;
3), select suitable cascade solidity L/t, wherein t is pitch, t=2 π R/z, and in formula, R is the distance that shaft centre line is arrived in cross section, and z is the number of blade;
4), number of blade z=3 ~ 5 slice, as pump specific speed n
stime larger, z gets the small value;
5), on each streamiline surface, aerofoil profile laying angle β
mdetermine:
Adopt β
m=(β
1+ β
2)/2 represent.β in formula
1for vane inlet laying angle,
v
mfor axial velocity in impeller, u is axial velocity on this streamiline surface, Δ β
1for the vane inlet angle of attack.β
2for blade exit laying angle,
v
u2for the component of this streamiline surface upper outlet peripheral velocity in absolute velocity direction;
6), maximum blade thickness δ
maxdetermine:
δ
maxrelevant with chord length L on this cross section, general δ
max/ L=0.1 ~ 0.15; Wheel hub maximum blade thickness δ
maxcan adopt
in formula, H is pumping head; The maximum ga(u)ge that other aerofoil sections go out is according to linearly reducing Long-term change trend;
7), the determination of maximum ga(u)ge position, each aerofoil section place: for ease of statement, adopt φ to represent, choose other suction surface streamline distribution even transition of φ=0.51 ~ 0.85..
Embodiment 1:
Obtain axial-flow pump Operational Limits: flow Q=910m
3/ h, lift H=5.25m, rotating speed n=1450r/min, specific speed n
s=767.20; Carry out traditional axial-flow pump impeller computational process:
Impeller member and main geometric is determined: according to description, obtains the member and main geometric of impeller, wherein impeller outer diameter D=300mm; Get hub ratio d
h/ D=0.45; Number of blade Z=4 sheet; Comprise wheel hub, blade, interior, is divided into 5 streamiline surfaces by wheel rim; Other geometric parameters are see table 1.
Table 1
By above-mentioned parameter, the axial-flow pump impeller designed with abovementioned steps carries out cavitation performance testing experiment, obtains adopting traditional design method, and also namely when φ=0.4, its cavitation performance curve as shown in Figure 3.Can obtain from Fig. 3, as device net positive suction head NPSH
aduring=4.57m, when comparing non-cavitating state, lift declines 3%, can obtain, now the necessary NPSH NPSH of pump according to pump necessary NPSH relevant criterion
r=NPSH
a=4.57m, pump hydraulic performance reduces obviously.
Embodiment 2:
For the ease of comparing, except change φ value, guarantee pump operation parameter and other geometric parameters of blade constant.Namely adjust φ value, when meeting φ=0.6, obtain its cavitation performance curve by test, as shown in Figure 4.Now work as NPSH
aduring=4.21m, pumping head declines 3%, in like manner can obtain, the necessary NPSH NPSH of pump
r=NPSH
a=4.21m.Compared with the traditional design method (φ=0.4) in embodiment 1, the necessary NPSH NPSH of pump
rhave dropped 7.88%, cavitation performance is improved, and pump hydraulic performance is guaranteed.
Embodiment 3:
Ensure pump operation parameter and other geometric parameters of blade constant, further adjustment φ value.When also namely meeting φ=0.69, obtain its cavitation performance curve by test, as shown in Figure 5.Now work as NPSH
aduring=3.93m, pumping head declines 3%, therefore, under this scenario, and the necessary NPSH NPSH of pump
r=NPSH
a=3.93m.And compared with traditional design method (φ=0.4), the necessary NPSH NPSH of pump
rhave dropped 14%, cavitation performance obtains further improvement.
Known by above-mentioned three embodiments, after employing parameter value mode provided by the present invention, the necessary NPSH of pump declines obviously, and cavitation performance obtains further improvement, thus achieves the anti-cavitation effect before axial-flow pump impeller manufacture reliably.Because the present invention is without the need to carrying out later stage constructional variant, the cost that also can reduce post-production accordingly and the artificial destruction avoiding original design runner, the integrity of runner is also preserved, fabricating cost have also been obtained further reduction, obviously very meets the modernization industry demand of the high efficiency of current axial-flow pump impeller manufacturer, low fabricating cost and high quality of finished.
Claims (1)
1. an anti-cavitation axial-flow pump impeller design method, is characterized in that: in blade pressure surface calculation of streamlines step, and the ratio getting aerofoil profile chord length L in thickness place, impeller aerofoil profile maximum cross-section to wing type head distance l and this cross section is 60% ~ 69%.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201510908837.0A CN105443433A (en) | 2015-12-08 | 2015-12-08 | Design method for cavitation-resistance axial flow pump impeller |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201510908837.0A CN105443433A (en) | 2015-12-08 | 2015-12-08 | Design method for cavitation-resistance axial flow pump impeller |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN105443433A true CN105443433A (en) | 2016-03-30 |
Family
ID=55553978
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|---|---|---|---|
| CN201510908837.0A Pending CN105443433A (en) | 2015-12-08 | 2015-12-08 | Design method for cavitation-resistance axial flow pump impeller |
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN107066686A (en) * | 2017-02-22 | 2017-08-18 | 江苏大学 | A kind of axial-flow pump impeller Hydraulic Optimizing Design method based on genetic algorithm |
| CN109763995A (en) * | 2019-02-13 | 2019-05-17 | 江苏大学 | A kind of axial-flow pump impeller design method based on wheelbase |
| CN109800482A (en) * | 2018-12-29 | 2019-05-24 | 合肥工业大学 | A kind of design method of small hub than impeller |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2002021787A (en) * | 2000-07-05 | 2002-01-23 | Fujitsu General Ltd | Impeller of axial blower |
| CN101629583A (en) * | 2009-06-23 | 2010-01-20 | 江苏大学 | Methods for calculating and thickening profile of impeller vane of axial flow pump |
| CN104763473A (en) * | 2015-02-12 | 2015-07-08 | 溧阳市超强链条制造有限公司 | Wing-shaped part |
-
2015
- 2015-12-08 CN CN201510908837.0A patent/CN105443433A/en active Pending
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2002021787A (en) * | 2000-07-05 | 2002-01-23 | Fujitsu General Ltd | Impeller of axial blower |
| CN101629583A (en) * | 2009-06-23 | 2010-01-20 | 江苏大学 | Methods for calculating and thickening profile of impeller vane of axial flow pump |
| CN104763473A (en) * | 2015-02-12 | 2015-07-08 | 溧阳市超强链条制造有限公司 | Wing-shaped part |
Non-Patent Citations (1)
| Title |
|---|
| 罗剑: "翼型选择对轴流泵汽蚀抑制的研究", 《中国优秀硕士学位论文全文数据库》 * |
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN107066686A (en) * | 2017-02-22 | 2017-08-18 | 江苏大学 | A kind of axial-flow pump impeller Hydraulic Optimizing Design method based on genetic algorithm |
| CN107066686B (en) * | 2017-02-22 | 2020-09-25 | 江苏大学 | Axial flow pump impeller hydraulic optimization design method based on genetic algorithm |
| CN109800482A (en) * | 2018-12-29 | 2019-05-24 | 合肥工业大学 | A kind of design method of small hub than impeller |
| CN109800482B (en) * | 2018-12-29 | 2020-12-18 | 合肥工业大学 | Design method of impeller with small hub ratio |
| CN109763995A (en) * | 2019-02-13 | 2019-05-17 | 江苏大学 | A kind of axial-flow pump impeller design method based on wheelbase |
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Application publication date: 20160330 |