US1769886A - Double-runner spiral pump - Google Patents

Description

July l, 1930. F. MOODY 1,769,886

DOUBLE RUNNER SPIRAL PUMP Filed April 7, 192e 35% 14M @lbtowwl/b Aoppositely directed impellersclosely spacedV Patented July 1, 1930 narran states earner ostina LEWIS FERRYMOODY, OF PHILADELPHIA, PENNSYLVANIA DOUBLE-RUNNER SPIRAL P'UlYIIP Application filed April 7,

Thisinvention relates to hydraulic pumps, and particularly to high-speed propeller type pumps of the double or twin type.'

Onecof the/objects of this invention is to provide a pump containing two impellers of 'opposite hand, to rform a. pump of high speciiic speed, high efficiency, and of compact design, in which the iiow shall proceed without being subjected to contact with excessive areas of confining walls in the region ofA the 4highvelocity flow in order to avoid excessive lossof head1 due to. surface resistance, whileV at thel same V.time .the flow shall follow smoothlines without losses dueto eddies or disturbances. Another object is to provide a pump of this character .which is ,simple in construction, small in act-ual dimensions, ofv

lightweight, and formedof few parts. i'

5A.ffurther object of vtheinvention is to provide a pump of this character with its toeach other and without unnecessary and objectionable directing surfaces interposed between the impellers Ato provide forced guidance ofthe discharge from the impellers into the outwardi'direction. v

vFurther objects and advantages of the Yinvention will be apparent by reference .to the following specication and drawings in which"` 4 Fig. 1 is a sectional View on line 1-1 of Fig. 2, and

Fig. 2 is a vertical sectional view online 2-2`of Fig.V 1.k

In the specific embodiment of the inven- V tien illustrated 10 'represents' a central volute ,outlet casing, 11 and 12 similar intake casings, and 18 and lvrepresent similaraxial flow propeller typeimpellers having unshrouded blades mounted upon a centralV shaft 15. rEhe intake casings-11 and 12 are each formed with an intake passage 16,

1T leading to the inclined guide vanesrlS'l A'lheintake passages may be of..

and 19. the single or double volute form and serve to direct the water from a generalradial direction into an axial direction to passages 20-20. From these points the passage walls turn outwardly. The impellers 13 and 14 are keyed or otherwise secured on the shaft 15Y 19%.. Serial No. 100,207.

and are held'against lateral displacement by j l y means of collers 21and 22 bolted or otherwise secured to the shaft 15. The collars 21 and 22'serve to hold the impeller against a straight central cylindrical spacer in the form ofa sleeve 23. Collar 21 may be in- Inpractice thejwater entering the passages L 1G and 17 is .given the desired degreeof whirl by entrance vanes 18and 19, and thence passing through the passages 20-20 is delivered to the impellers 13 and 14 in the form of solid whirling streams, the water from both iinlpellers oining toform a single continuous rotating mass of water.y Issuing from the im pellers i the ilow passes outwardly into Vthe outlet 10 and proceedingfromv the impeller 7v the water is underfpressure and will follow natural streamlines to turn without the necessity ofany enlarged central core or den flector between them. The whirling flow in leaving the impellers and passing outwardly u into the casinglO .will pass .from points near the axis toicontinually greater and greater radial distances .from .the axis'a-nd will be thereby decelerated, according to the principle of constancy of moment of momentum, according to which the linear velocity of rotation of fluid, contained within the free space is inversely proportional to its radial distance from the axis.

Thecasing will, in general, be designed to conform to the velocitydetermined by this principle and to provide continuous deceleia tion of velocity as the water flows through the casing. Y The casing 10 is formed wit-h a throat opening of reduced width between the opposing wallsqat a point a short dist-ance outside of the vimpeller tips in order to hold the` streams of water together and to avoid any tendency of the natural lines of flow to part from-the walls. A. casing throat measured in an axial direction will usually be less than about three-fourths of the impeller diameter in order to conform to the How. Outside of this throat section where the outward 5 radial components of velocity become suffimay be easily assembled, as will be seen by an ine ction of the drawings. The casngs will or arily be in t-wo pieces separable on a horizontal plane containing the axis to facilitate removal of the shaft and impellers.

umps of the spiral type to which this invenA ion apslies the recovery of the energy of thewater ischarged from the impellers is unimportant part of the hydraulic action of the pump, since this ener represents a value iu'high'speed umps o this type which is lar' compare to the net head against which the pump is delivering.

J "flhe entranceguide-vanes 18, 19 are formed sito lguidethe water in a direction of rotation ab u tithe impeller axis, this initial rotation i for the entering water being in the same sense asithe rotation of the impeller. For pumps of special `characteristics, theguide-vanes 18,

19 may be omitted, the water then being ermi to take up its natural degree of w irl without *forced guidance, the omission of the guida-vanas producinY in eneral a less rapidly falling curve Aofthea relatively to discharge.

The impellers are of high specific eed, havingblades which when cut by cylin rical surfaces 'about the axis are of curved section inclined at relatively small angles to the tangentili direction, that is, the direction of motionof the blades. The blades are of relatively smallsurface area, `not materially greater in aggregate surface than the disk area, or net area of the runner passage in a plane normal to the axis; and to avoid undue surface resistance the impeller is free from ggg shroud ring surrounding theA blades.

i enviewed axially the blades do not overr1113K each other in the portion near their tips.

eimpeller will have a small number of blades, usually between three and six. For hydraulic reasons the hubs and sleeve 23 must obe unduly small, but should be of substantial diameter. i A

The impeller may have blades extending radially outward from the hub, or slightly inclined to the axis when viewed in a sectionfcontaining the axis as shown in Fig. 1. In the design shown, the discharge from the portion of the blades near the hub is axial or nearly axial, while the discharge from the ,'tioni (if the blades near the tips has an outwardler'adial component, the turning of the waterifrom axial to radial beginning within the `runner. The iows from both runners constructed of castings and the entire casing near the hubs are allowed to join and turn from axial to radial along their natural lines of flow according to hydrodynamic principles, this turning being produced by an increase in pressure head and corresponding reduction of velocity head where the streams join near the center of the surface of sleeve 23. By omitting any forced guidance of the fiow as by an enlarged conical body between the runners, surface friction is minimized, the structure is made compact with the runners close together, and it becomes unnecessary to support a large central deflecting body, either by carrying it on the rotating shaft -or by ribs extending from the fixed casing.

Vhile this invention is illustrated and described more particnariy with reference to hydraulic pumps having a central dischar passage and separate intake passages it 1s not confined thereto but is intended to cover hydraulic pumps having a central intake passage and separate discharge passages and any other modifications within the scope of the appended claims.

I claim:

1. A rotary hydraulic pump having in combination two oppositely disposed unshrouded impellers of approximately axial flow ty, a casing having a single central passage tween said impellers, walls forming the outside boundary of a transition space and having surfaces of revolution smoothly curving from the impeller tips to the casing entrance, and an inside boundary wall of said transition space comprising a sleeve which is continuous in contour with the impeller hubs, and at no pointmaterially greater in diameter than said impeller hubs.

2.`A rotary hydraulic pump having in combination two oppositely disposed unshrouded impellers of approximately axial How type, a single volute discharge casin receiving the discharge from both of sai impellers, walls forming the outside boundary of a transition space and having surfaces of revolution smoothly curving from the impeller tips to the casing entrance, and an inside boundary wall of said transition space comprising a. sleeve which is continuous in contour with the impeller hubs, and at no point materially greater in diameter than said impeller hubs.

3. A rotary hydraulic pump having in combination two oppositely disposed unshrouded impellers of approximately axial flow type, a singlevolute dischar e casing receiving the discharge from both 0% said impellers and gradually decelerating the velocity of said discharge, walls forming the outside boundary of a. transition space and having surfaces of revolution smoothly curv ing from the impeller tips to the casin entrance, and an inside boundary wall o said transition space comprising a sleeve which is continuous in contour with the impeller the low from approximately axial to a radialr outward direction. v'

4. A vrotary hydraulic pump hav-ing m combination two oppositely disposed un-V shrouded impellersy of approximately axial flow type, a single volute discharge casing receiving the'discharge from both of said impellers, a common transitionl spacel the walls of'which turn the discharge from sait Vimpellers from approximately axial to a radial direction, the discharge from both of said impellers being permitted to merge freely along a transverse plane midway between said impellers without theinterposition of than the outside diameter of either of saidv impellers.

6. A rotary hydraulic pumpY having'in combination two' oppositely disposed unshrouded impellers of approximately axial flow type, a singlevolute` discharge Vcasing receiving'the discharge from both of said impellers, and a common transition space, the walls of which turn the discharge from said impellers from. approximately axial to a radial direc-tion, the discharge from both of said impellers being permitted to merge freely along a transverse plane Lmidway between said impellers, said impellers being separated by an axial distance `less than the outside diameter of either of said impellers.

7 A rotary hydraulic pump havingl in v combina-tion two oppositelv disposed unshrouded impellers of approximately axial flow type, a single volute discharge casing receiving the discharge from both of said impellers, and a common transition space, the walls of which turn the discharge from said impellers from approximatelyn axial to a radial direction, thev discharge from both of said impellers being permitted to merge freely along a transverse plane midway between said impellers, said impellersy being spaced 'apart at a relatively small distance and surrounded by a wall formingV a' surface of revolution converging along a smooth curve to a minimum diameter at or near the entrance ofthe impeller and then continuously vcurving outward away fromA the' axis toaradial direction at entrance to .thevolute casing. i

Si.V A rotary hydraulic pump having in combination two oppositely disposed unshroudedimpellersA of axial flow type, and a single volute dischargey casing receiving the discharge from both of said impellers, said' impellers being spaced by a substantially cylindrical sleeve.

9. A rotary hydraulic pump having in combination two oppositely disposed propeller type impellers secured to the same shaft, and a single volute discharge casing receiving the discharges from both of said impellers, said impellers being spaced by a cylindrical sleeve secured to said shaft androtating with said impellers.

l0. In aI double pump the combination with a central volute passage, of a cylindrical substantially straight sleeve therein, of a runner on each side thereof, anda plurality of outward passages leading from the runners to the volute passage and discharging therein. 'i

ll. In a twin hydraulic pump a Icentral outlet casingand a pair of inlet casings, said inlet and outlet casings being formed with continuous inlet and outlet passages, a pair of impellers in said passages, a shaft upon which said impellers are mounted, and a substantially straight cylindrical sleeve on said shaft spacing the impellers.

l2. Vln a twin hydraulic pump a central outlet casing and a pair of inlet casings, said inlet and outlet casings being formed with continuous inlet and outlet passages, a pair of impellers in said partages, a shaft upon which said impellers are nnuinted7 and substantially straight cylindrical sleeve attached to said shaft forspacing the impellers and rotating therewith, and guide vanes in the inlets to said impellers. y

13. ln a double vpump aV c 'ral casing comprisingl an outer wall a substantially straight cylindrical sleeve, said wall and sleeve forming between them a volute discharge passage, annular passages discha ng axially into said volute, and impellers i said annular passages. v

la. A double pump having a central 'caslng formed of an outer wall, a cylindrical sleeve, said wall and sleeve forming between them a volute discharge passage, annular passages communicating therewith, impellers in said annular passages, a sh t extending through said sleeve and carrying said impellers. and an intake passage to each impeller contained between an outer converging surface of revolution and an inner surface of revolution coaxi al therewith.

l5. In a hydraulic pump the combinatio with a plurality of unshrouded impellers of substantially axial flow type, of an impeller casing surrounding each of said impellers and acentral volutecasing, each of said impeller All i having walls formed as surfaces of revolution smoothly curving from axial to radialdirection to form a throat and merging into the walls of the central volute casing and e through a vane-free passage directly utnisaid central volute casing which flares i'xinllybeyond said throat.

fltphr. a hydraulic piunp thecombination with a central volute casing of a substantially `egflilldlfoal sleeve within said casing, an imf 0n each Side of said sleeve, guide vanes in advance of each impeller and a plurality offoutward passages leading from the impellers-to the central volute passage and discharging therein.

.17.. In a hydraulic pump the combination with a central volute casing, of a substantial- 1y cylindrical sleeve within said casing, an unshrouded impeller of substantially axial type on each side of said sleeve, fixed glde vanes in advance of each impeller and a plurality of outward passages leading from the impellers to the central volute casing and discharging therein.

18. A rotary hydraulic pump having in combination two oppositely disposed unshrouded impellers of approximately axial flow type, a single volute discharge casing receiving the discharge from both of said impellets, and inner and outer walls foi-min a eommon transition space the inner wall extendin relatively close and substantially parall to the axis of the impellers for substantially the entire distance therebetween, said transverse space turning the discharge from said impellers from approximately axial to a radial direction, the discharge from Said impellers merging freely between said impellers.

19. A rotary hydraulic pump having in combination two oppositely disposed unshrouded impellers of approximately axial flow type, a single discharge casing receiving a discharge from both of said impellers, walls forming the outside boundary of a free transition space having surfaces of revolution curving from the impeller tips to the cas- `entrance and an inside boundary wall ot' said transition space formed by a sleeve centinuous in contour with the impeller hubs and smaller in diameter than the diameter of the impellers to permit the flows from the impellers to freely merge between them.

` 20. In a hydraulic pump the combination with a plurality of unshrouded impellers of substantially axial How type, of fixed guidevanes in advance of each impeller, an impeller casing surrounding each of said impellers and a central volute casing, each of said impeller casings havinV walls smoothly curving and merging into tie walls of the central volute casing and forming a va ne tree pass-.ige opening directly into said central volute 21. rotary hydraulic pump having in combination two oppositely disposed unshrouded impellers of approximately axial flow type, a casing having a single central passa e between said impellers, walls forming t e outside boundary of a transition space and having surfaces of revolution smoothly curving from the impeller tips to the casing throat, and an inside boundary wall of said transition space comprising a sleeve which is continuous in contour with the impeller hubs and at no point materially greater in diameter than said impeller hubs.

22. In a h draulic Pump the combination with a plura ity of impellers of substantially axial low type, of an impeller casing surrounding each of said impellers and a central volute discharge casing, means ior producing two whirling streams axially progressing toward each other, said impellers rotating in the same direction as the streams and acting upon said streams and discharging said streams toward each other, and means whereby the two streams freely merge between said impellers along a transverse plane midway between said impellers including a wall of said rotating element extending between the hubs of the im ellers, said wall being everywhere materia ly smaller in diameter than said impellers whereby a relatively unobstructed axially extending passage is provided between said impellers thereby to eilect said free merging.

23. In a h draulic pump the combination with a plurality of impellers of substantially axial fiow type, of an impeller casing surrounding each of said impellers and a central volute casing having a relatively unobstructed axially extending transition space between saidimpellers lixed guide vanes in advance of said impellers to impart a whirl to the fiow for producing two whirling streams axially progressing toward each other, said impellers rotating in the same direction as the streams and acting upon said streams and dischargin said streams toward each other whereby t e two streams are etliciently merged between said impellers along a transverse lane midway between said impellers.

24. n a hydraulic pump the combination with a plurality of impellers of subst-antiall axial `fiow type, of fixed guide vanos in a vance of each impeller, an impeller casing surrounding each of said impellers and a central volute casing, each of said impeller casings having walls smoothly curving and merging into the walls of the central volute casing and opening directly into said central volute casing without a central deflecting surface, said walls forming a transition space between the guide vanos and impellers, and a second transition space between the impellers and said central volute casing.

25. A rotary hydraulic pump having in combination two oppositely disposed axially spaced unshrouded impellers of substantial- Utl lut

llt)

ly axial flow type, an impeller casing surrounding each of said impellers and a single central volute casing having a relatively clear axially extending transition space between said impellers, said space having a radial depth extending for a major portion of the distance from the hub to the blade tips, said impellers being of high specilic speed and having a relatively small number of blades, not less than 3, the area of whichis not materially greater in aggregate surface than the disk area of the passage in the impeller casing in which the impeller is located.

26. In a rotary hydraulic pump having in combination two oppositely disposed unshrouded high speed impellers of substantially axial flow type provided with a relatively small number of blades not less than three, an impeller casing surrounding each impeller, said inipellers being spaced apart axially and with a relatively clear transition space therebetween said clear space having a radial depth extending substantially from the hub to the blade tips, and a single central volute casing, said blades having a relatively small surface area non-overlapping in the portion near their tips when viewed axially.

27, A rotary hydraulic pump having in combination two oppositely disposed axially spaced unshrouded high speed impellers of substantially axial liow type, an impeller casing for each impeller and a single central volute casing having a relatively clear axially extending transition space between said impellers, said space having a radial depth extending for a major portion of the distance from the hub to the blade tips, said volute casing also having a throat less than threefourths of the greatest diameter of the impellers in order to conform to the flow, each of said impeller casings having walls smoothly curving and merging into the walls of the central volute casing.

LEWIS FERRY MOODY.

Images