DK147187B

DK147187B - DIFFUSOR FOR AN AXIAL PUMP OR SEMI-SHAFT PUMP

Info

Publication number: DK147187B
Application number: DK005079AA
Authority: DK
Inventors: Hugh D Nelson
Original assignee: Mono Pumps Ltd
Priority date: 1978-01-06
Filing date: 1979-01-05
Publication date: 1984-05-07
Also published as: JPS54101502A; BR7900053A; NL7900114A; GB2012361B; DK147187C; DK5079A; ATA9979A; SE7900078L; FR2414129A1; DE2900095A1; GB2012361A; IN150721B; CS207738B2; AT360345B; ZA787315B

Description

147187 i147187 i

Opfindelsen angår en diffusor til en aksial- eller halv-aksialpumpe af den i indledningen til krav 1 angivne art.The invention relates to a diffuser for an axial or semi-axial pump of the kind specified in the preamble of claim 1.

Sådanne pumper fremstilles sædvanligvis som éttrinspum-per eller som flertrinspumper, hvor de forskellige trin 5 er ko-aksiale, og hvor en omgivende kappe udgør pumpens hus. Det enkelte trin eller hvert af trinene danner en pumpeenhed bestående af en rotor med skovle eller en propeller. Denne rotor fører væskestrømmen ind i en diffusor med skovle, som gør væskestrømmen aksial eller til-10 nærmelsesvis aksial i forhold til huset og reducerer strømningshastigheden, så at i det mindste en del af strømmens hastighedsenergi omdannes til trykenergi.Such pumps are usually manufactured as single-stage pumps or as multi-stage pumps, where the various steps 5 are coaxial and where a surrounding jacket forms the pump housing. Each stage or each stage forms a pump unit consisting of a rotor with vanes or a propeller. This rotor introduces the fluid flow into a diffuser with vanes which make the fluid flow axial or approximately axial to the housing and reduce the flow rate so that at least part of the flow velocity energy is converted to compression energy.

Et eksempel på en kendt éttrinsaksialpumpe er vist i fig.An example of a known single-stage axial pump is shown in FIG.

1 og 2. Fig. 1 viser et lodret længdesnit, og den øvre 15 del af fig. 2 viser i udfoldning to naboskovle i den i fig. 1 viste diffusor samt væskestrømningslinjer, medens den nedre del af fig. 2 er et halvplan fremkommet ved projektion af figurens øvre del.1 and 2. FIG. 1 is a vertical longitudinal section and the upper portion of FIG. 2 shows two neighboring vanes in the embodiment of FIG. 1 and liquid flow lines, while the lower part of FIG. 2 is a half-plane formed by projection of the upper part of the figure.

Den i fig. 1 og 2 viste kendte pumpe har et hus, der 20 er dannet af et tragtformet indløbsskørt 7, en rørformet diffusorsektion 3 og en mellemliggende sektion 9, som omgiver en rotor 10 med skovle og en stator 11. Rotoren 10 er fastkilet på en drivaksel 12, der er monteret i et nedre leje 13 og et øvre leje 14. Sektionen 8 spreder 25 mediet, idet den vider sig ud i strømretningen, og idet en forlængelse 15 af lejet 14 snævrer ind i strømretning.The FIG. 1 and 2, a housing 20 formed by a hopper inlet skirt 7, a tubular diffuser section 3 and an intermediate section 9 surrounding a rotor 10 with vanes and a stator 11. The rotor 10 is wedged on a drive shaft 12 mounted in a lower bearing 13 and an upper bearing 14. The section 8 spreads the medium as it expands in the flow direction, and an extension 15 of the bearing 14 narrows in the flow direction.

Aksialpumper af denne art har vist sig at være tilfredsstillende i de fleste henseender. De har imidlertid den ulempe, at der opstår et betydeligt energitab på grund 30 af kavitation og/eller turbulens i diffusoren. I fig. 2 147187 2 er vist strømlinjer 16 mellem et par naboskovle 17, og en strømlinje 18 illustrerer den tendens, der er til modstrømning, som foranlediger kavitation og turbulens.Axial pumps of this kind have been found to be satisfactory in most respects. However, they have the disadvantage that a significant energy loss occurs due to cavitation and / or turbulence in the diffuser. In FIG. 2, streamlines 16 are shown between a pair of neighboring vanes 17, and a streamline 18 illustrates the tendency for counterflow that causes cavitation and turbulence.

Som ovenfor nævnt udøver diffusortrinene i en flertrins-5 aksialpumpe eller diffusororen i en éttrinspumpe normalt en strømudrettende virkning og omdanner en del af den pumpede væskes kinetiske energi til trykenergi.As mentioned above, the diffuser stages of a multi-stage axial pump or the diffuser of a single-stage pump usually exert a current-directing effect and convert some of the kinetic energy of the pumped fluid into pressure energy.

Traditionelt udføres denne strømudretning og energiomdannelse samtidigt. Ved pumpning af gas er dette en 10 bekvem måde, hvorpå diffusortrinet kan gøres kort i ak-sial retning og hele pumpen således kompakt.Traditionally, this power alignment and energy conversion are performed simultaneously. In pumping gas, this is a convenient way of making the diffuser step short in the axial direction and thus the whole pump compact.

Opfindelsen har til formål at angive en diffusor af den omhandlede art, som medfører en reduktion af den kavitation, der optræder ved pumpning af væsker.The invention has for its object to provide a diffuser of the kind in question which causes a reduction of the cavitation which occurs when pumping liquids.

15 Dette formål opnås ved, at diffusoren er udformet som angivet i krav l's kendetegnende del. Denne virkning hidrører fra, at energiomdannelsen er adskilt fra strømudretningsfunktionen. Således virker det nævnte første aksiale afsnit af diffusorpassagen alene som en diffu-20 sor og foretager en effektiv omdannelse af kinetisk energi til trykenergi. Væsken træder ind i diffusorens indstrømningsende ad en skruelinjeformet bane og fortsætter langs en sådan bane gennem hele det første aksiale afsnit, hvorefter den underkastes strømudretning med eller 25 uden en svag yderligere energiomdannelsesfunktion.This object is achieved by the diffuser being designed as defined in the characterizing part of claim 1. This effect is due to the fact that the energy conversion is separate from the power straightening function. Thus, said first axial section of the diffuser passageway acts solely as a diffuser and makes an efficient conversion of kinetic energy to printing energy. The liquid enters the inflow end of the diffuser along a helical path and proceeds along such path throughout the first axial section, after which it is subjected to current alignment with or without a weak additional energy conversion function.

I hele det første aksiale afsnit foregår der en meget gradvis forøgelse af væskestrømmens tværsnit med deraf følgende gradvis diffusionsvirkning, som muliggør kavi-tationsfri omdannelse af kinetisk energi til trykenergi.Throughout the first axial section, there is a very gradual increase in the cross-section of the fluid flow, with the resultant gradual diffusion effect, which enables the cavitation-free conversion of kinetic energy to pressure energy.

3 147187 Først når denne omdannelse er gennemført i ønsket udstrækning, i hvert fald tilnærmelsesvis, udrettes strømmen til afgivelse fra diffusoren eller indføring i det næste rotortrin.Only when this conversion is completed to the desired extent, at least approximately, is the flow to be dispensed from the diffuser or introduced into the next rotor stage.

5 Opfindelsen vil blive nærmere beskrevet i det følgende under henvisning til tegningen, hvor fig. 3 er en afbildning svarende til fig. 2 og viser i udfold-ning taget ved forbindelsen melem statorens skovle og dens kappe en udførelsesform for statoren ifølge opfindelsen, og 10 fig. 4-6 viser i perspektiv yderligere udførelsesformer for statoren ifølge opfindelsen.The invention will be described in more detail below with reference to the drawing, in which 3 is a view similar to FIG. 2, showing in unfolding the connection between the blades of the stator and its sheath, an embodiment of the stator according to the invention; and FIG. 4-6 show in perspective further embodiments of the stator according to the invention.

Som vist i fig. 3 strækker et par naboskovle 19 på diffusoren sig mellem en indstrømningsendeflade 20 for fluidum og en udstrømningsendeflade 21. Skovlene har tilnærmelsesvis kon-15 stant tykkelse over hele deres længde. Passagens akse er ret-liniet, og i et første aksialt afsnit 22, der udgår fra fladen 20, er dens overflader ligeledes retliniede og divergerer i en passende vinkel på mellem 2° og 8°, hvorved de udgør en effektiv retliniet diffusor med maksimum effekt 20 til omdannelse af hastighedsenergi til trykenergi. Efter at denne energiomdannelse har fundet sted, ændres strømningsretningen, idet det første aksiale afsnit 22 går over i et andet aksialt afsnit 23, der danner en krumning og ender i udstrømningsenden 21.As shown in FIG. 3, a pair of neighboring vanes 19 on the diffuser extend between a fluid inlet end 20 and an outflow end 21. The vanes have approximately constant thickness over their entire length. The axis of the passage is straight, and in a first axial section 22 projecting from the surface 20, its surfaces are also straight and diverge at an appropriate angle of between 2 ° and 8 °, thereby forming an effective rectilinear diffuser with maximum power 20 for converting velocity energy to pressure energy. After this energy conversion has taken place, the flow direction changes, with the first axial section 22 moving into a second axial section 23 which forms a curvature and ends at the outlet end 21.

25 Med den beskrevne stator kan strømningsmønsteret for væsken, der forlader propelleren som antydet ved strømningslinierne 24, betragtes som en familie af lige linier, der tangerer rotorskovlenes spidser ved udgangsenden af rotoren.With the described stator, the flow pattern of the fluid leaving the propeller as indicated by the flow lines 24 can be considered as a family of straight lines tangent to the tips of the rotor blades at the output end of the rotor.

4 1471874 147187

Fig. 4 viser anvendelse af opfindelsen på en mellemliggende diffusor i en flertrinspumpe. De brudte'linier 25 angiver de retliniede, men divergerende partier af væske-passagerne i det første aksiale afsnit 22, som tangen-5 tialt går over i krumme partier, som udmunder i strømnings-endefladen 26. Som vist i fig. 4 øges diameteren både af navet 32 og af kappen 33 i det første aksiale afsnit, medens disse diametre begge formindskes - mest udtalt for så vidt angår kappen - i det andet aksiale afsnit..FIG. 4 shows application of the invention to an intermediate diffuser in a multistage pump. The broken lines 25 indicate the rectilinear but divergent portions of the fluid passages in the first axial section 22, which tangentially pass into curved portions which open into the flow end surface 26. As shown in FIG. 4, the diameter is increased both by the hub 32 and by the sheath 33 in the first axial section, while these diameters are both reduced - most pronounced in the case of the sheath - in the second axial section.

10 Dette bevirker, at hver strømningspassages største tværsnit findes ved overgangen mellem det første og det andet aksiale afsnit, dvs. ved overgangen fra retliniede passager til de krumme passager.This causes the largest cross-section of each flow passage to exist at the transition between the first and the second axial sections, ie. at the transition from straight lines to curved passages.

Fig. 5 viser anvendelse af opfindelsen på den bageste 15 diffusor i en flertrinspumpe, hvilken diffusor foruden at være indrettet til at ændre strømningsretningen, i hovedsagen som det er beskrevet i forbindelse med fig. 3, også tjener som en slutdiffusor til erstatning for den diffusion, der tilvejebringes af den i fig. 1 viste sek-20 tion 8 og lejeforlængelse 15. I fig. 5 viser de brudte linier 27 den retliniede, men divergerende udformning af indløbsdelen af en væskepassage, der ligger mellem et par skovle, og som går tangentialt over i krumme partier, der udmunder i udstrømningsendefladen 28. Som det frem-25 går af fig. 5, formindskes navet 34's diameter igen i det andet aksiale afsnit, men i dette tilfælde forøges kappen 33's diameter gradvis, så at hver strømningspassages største tværsnit findes ved udstrømningsenden 28.FIG. 5 shows the application of the invention to the rear diffuser in a multistage pump, which in addition to being arranged to change the flow direction, substantially as described in connection with FIG. 3, also serves as a final diffuser to replace the diffusion provided by the one shown in FIG. 1, section 8 and bearing extension 15. In FIG. 5, the broken lines 27 show the rectilinear but divergent configuration of the inlet portion of a fluid passage lying between a pair of vanes and tangentially passing into curved portions which open into the outflow end surface 28. As can be seen in FIG. 5, the diameter of the hub 34 is reduced again in the second axial section, but in this case the diameter of the sheath 33 is gradually increased so that the largest cross-section of each flow passage is found at the outlet end 28.

Fig. 6 viser anvendelse af opfindelsen på en pumpe med 30 sideafgang. De brudte linier 29 viser naboskovle, der strækker sig retliniet, men divergerende fra en indstrømningsendeflade 30 og går tangentialt over i krumme partier, der udmunder i udstrømningsendefladen 31.FIG. 6 shows the application of the invention to a 30-side discharge pump. The broken lines 29 show neighboring vanes extending the rectilinear but diverging from an inflow end surface 30 and tangentially into curved portions which open into the outflow end surface 31.

5 1471875 147187

Ved at sammenligne fig. 4 og 5 vil man se, at passagernes største tværsnit ved den i fig. 4 viste udførelsesform findes i det område, hvor passagens retliniede, divergerende partier går over i de krumme dele, medens passa-5 gernes største tværsnit i fig. 5 findes ved ctiffusorens udstrømningsendeflade.By comparing FIG. 4 and 5, it will be seen that the largest cross-section of the passageways at the one shown in FIG. 4 is found in the region where the straight, divergent portions of the passage pass into the curved portions, while the largest cross-section of the passengers in FIG. 5 is located at the outlet end of the diffuser.

I fig. 4 og 5 er endefladerne for væskeindstrømning og væskeudstrømning parallelle, medens de i fig. 6 er skrå i forhold til hinanden.In FIG. 4 and 5, the end faces of liquid inflow and liquid effluent are parallel, while in FIG. 6 are oblique to each other.

10 Enkelthederne ved de viste og beskrevne konstruktioner kan ændres på mange andre måder; f.eks. kan væggene i passagens retliniede parti erstattes med krumme vægge, der divergerer trompetformet.10 The details of the designs shown and described can be changed in many other ways; eg. For example, the walls of the passage's rectilinear portion can be replaced by curved walls that diverge trumpet-shaped.

Claims

147187

A diffuser for an axial or semi-axial pump and having an inflow end forming a face perpendicular to the pump axis (20) and an outflow end forming one perpendicular symmetry axis perpendicular (21), a center hub, an outer sheath and a a number of guide vanes (19) extending radially between the center hub and the sheath, each pair of adjacent vanes limiting a current passage extending from the inflow end of the diffuser to its outflow end, characterized in that each current passage in a first axial section (22) of known per se, the rectangle extends from the face (20) formed by the inflow end, and the diameters of the center hub and sheath of this section grow in such a ratio that the current passage gets a growing cross section, and each current passage in a different axial section (23) is curved and ends substantially perpendicular to the face (21) formed by the outflow end.

A diffuser according to claim 1, characterized in that the guide vanes (19) have a substantially constant thickness over their entire length.

A diffuser according to claim 1 or 2, characterized in that the guide vanes (19) in the first section (22) of each passageway during their connection with the outer sheath seen 25, diverge at an angle of between 2 ° and 8 °.

A diffuser according to claim 1, 2 or 3, characterized in that the diameters of the central hub and the outer sheath of the second section (23) decrease so that the maximum cross-section of each current passage is found at the transition