US841253A - Means for decreasing leakage in turbines. - Google Patents

Description

M 841,253. PATBNTED JAN. 15, 1507.

0. JUNGGREN.

MEANS POR DECREASING LEAKAGE IN TURBINES.

APPLIOATION FILED APR. 29; '1903.

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Inventor:

muy.

l"UNIT-RD STATES- rA'rnNfr OFFICE.-

. OSCAR JUNCCREN, or'jsC'HENRCrAnY, ,NEW YORK, AssrGNoR To .GENERAL ELECTRIC COMPANY.- A CORPORATION or NEWIVY'ORK.

.ectady,

MEANS FOB DEQREASING LAKAG 'iN Tu-HsiNEs.

' pplieationled *April 29,

To au whom it may concer-1L: l

Be it known that I, OSCAR JUNGGREN,'a citizen of the United States, residing .at Schenin the county of Schenectady, State of New York, have invented certain new and useful Improvements in Means for Decreasin'g the'Leakage in Elastic-Fluid Turbines',v of

. which the following is a specification.

' In elasticeiiuid turbines itis customary to rovide a cover forv the outer ends of the wheel-buckets in order to'coniine the'motive4 fluid to the passages between the buckets.v Situated between the wheel-buckets are sta` ceive the motive buckets and discharge it at the proper angle4 against .a second. set of wheel-buckets. Mani-l festly1 there must be ya clearance more or less A great between the relatively moving buckets, and through'this clearance considerable :steam or" other motive. iiuid leaks. The 'amount of thisleakage is also governed by the difference in .pressure betwe'en the column'of steam actually performing work and that in the surrounding-casing or shell. 'I'he greater the difference in pressure, other 'things bein equal, the `greater the leakage.

My inven ion has forits object to decrease the leakage at the clearances, and to accomplish this I provide a means whereby' a hi h resistance or op osition is offered to the/lea motive iuid. v,

The covers ordinarily employed on. thev wheel-buckets are very thin, varyingv in thickness from one-eighth to three-sixteenths -of an inch. Owing' to the thinnessofy the l cover, .the surface friction opposing the escape ofstea'm is verysma i.

lescapeof motive In carrylng out my invention I provide the bucket-covers with 'thickened edges, prefer-l ably taking "the form of circumferential flan es formedfinte al therewith. 'I he eX -g ten ed surfaces'of tIie thickenededge of the cover and the su ort for the'intermediates offer a consideray higher-resistance to the fluid than does the normal passagebetween the buckets. yThe opposition or resistanceto leakage isnot so'great, however,A as to prevent the water ofl conden sation, and expansion `from beingdischar ed under centrifugal forcel ,'.The' amount t at the ailge or flan es project beyond the cover varies` with the c aracter and 'size of thetur-`4 Letters Patent. lattenwlv Jan. 15,1907. A

.woefl serai No. 154.888.

` For a fuller consideration of what I believe. to be -novel and my invention attention is called to the description and claims appended thereto.

illustrate one embodiment of my invention, Figure 1 is a partial axial section of aturbine. Fig. 2 is asectional View of a wheel, takenon the line 2 2 of Fi .'1. axial section of a part o a bucket-wheel.. Fig. 4Y shows the bucket-Cover and interme- 'diate support grooved to further prevent leakage,l and Fig, 5' is adevelopment of the .tionaryfor intermediate buckets, which re- V sectional bucket-cover.

-iiuid from one set of wheel- 1 represents the turbine casing or shell, and secured thereto.' is an adjustable nozzle 2, `whchjrnaybe. of thev expanding or non-ex- 'anding type, as is desired. f In the particuar 'illustration it is intended to convert the ressure of the elastic fluid4 into .velocity and eliver itin the form of a jet to the buckets;

nozzle is secured in place vby bolts 3 and is adjustable toward'and away from the wheel in a plane parallel to its axis.- casing or shell is provided .with 4an opening through which projects the 'segmental `support for, the intermediate buckets'.l The' sup` portgis vprovided'with, aliange 4 of somewhat greaterv area than the o eningwhich is se 4cured tothe outsideof'tllfe lCasin by bolts 5. ,Between` hef`bodies of the bo ts and the f flan'ge is av small space, so that the intermediates can lbe vadjusted in'an `axial plane for the purpose of changingthe'clearances between them andthe wheel-buckets. The inh' selves measured in an axial plane; The ortion 8 of the su port adjacent to the wheel ticket-cover'y is a so 'somewhat wider' than y he buckets measured4 in an axial plane, so as to reduce the leakage and revent the sharpenededges of thebuckets om rubbing. The wheel-buckets 9 are each provided with a 'shank.`10, formed integral therewithat the vinner end, and these shanks are fitted into a circumferential groove formed in projections on the periphery of the wheel 11.

tend from one side to the otherof the saidi In 'theaccompanyingv drawings, which i 6o Fig. 3 is" an but my invention is not limited thereto.- The 'Theside of the The buckets are retained-inplace by pins 12', which eX'-A projection or raisedlportion formed Aon the wheel-periphery-` The pins` being somewhat.

shorter than .the distance. between -theproj ections can readily 4vbe slipped' into 'place and the ends peened over .afte'rw'.ard,v I-'The sides; ofthe projection arejin close `rnoiirn'ity to thc cover 7 of theintermediate lbu'ckets, so, as tol reduce the circumferential or cross leakage at this point. The buckets may be formed b y- .drop-forging or casting, v.as l desired,I and eacn bue cover 13, sometimes 'calle a` fitting and baffling strip,y which cover has two thickened edges formedintegra'l therewith, which in the present illustration take the form of circumferential flanges,14. `Infcrosssection the cover has the shape of a channel-beam; Thel clearance, measuredinv an. axial plane, `between the thickened edges or flanges 14 of the bucket-cover and the stationary parts, such as the nozzlcand the portion 8 of the'intermediate support, is made as small as ypossiyble consistent with good operation. Through this clearance the`waterl due to ,expansion and condensation can bedischarged; but the resistance or opposition to the passage of elastic motive fluid at ythis point 1s high. Thisl is owing to thelfactthat theflange presents an extended surface to" the stationary part, and the frictional'resistance offered -to the outward passage'of' steam at'this point is conside erably greater than theresistance oeredto the, passage ofsteam through'the'normal' or yworkingpassages between the buckets.

In other words, two paths are provided for the steam. or other elastic fluid, one of low resistance and thev other. of relatively high 'resiste ance, and owing to the fact that the jet-is traveling at high velocity due. tol the nozzle only a very small amount of steam'willv be `permitte'd'to escape vthrough the/circumferential clearance. The water due to eXpansion and condensation also' has a tendency to decrease the leakage'by wettingthe adjacent surfaces of the moving and stationary parts.

As the' intermediate buckets usually extend,-

thedifference in pressure between thel fluid stream and fluid or steam withinthe shell or casingv the greatery willhe the 'depthoffthe `flange becauseth'e tendency for the' steam to escape. at this ,point is correspondingly increased.

Referring 4to Fig. 2, it will `be seen that'the shanky 10 on each bucketis taperedyandengages with similar-Shanks on adjacent bucket is vrovided with a ets and that the lcover .13 of each bucket is also slightly tapered and engages 'with the lcover-sections of adjacent buckets. 'In this manner thegsteam or other motive fluid is confined to the working passages 15.-

Referring to Fig. 3,1 have shown a slight modification of the invention, wherein the wheel-buckets 9 are formedintegral With segmental supports 16, which in turn are secured to the wheel by bolts or'other attach- .ing means. i uIn this figure the line of division betweenthesegmental supports is'shown in l dotted lines. The buckets are provided with tenons 17, formed integral therewith, which register with openings formed in the cover 13,

sometimes calledv a fitting and baffling strip. The cover uis preferably madein se'ctions and is provided with thickened edges or flanges 14, as before. The tenons are riveted over to secure the cover-sections in place.

have the cover-sections embrace a number of the buckets, because ity simplifies vthe 'machine-work.

The-'intermediate vbuckets used with the different structures should be of a suitable form, capable of receiving the motivefluid from one row of wheel-buckets and changing its direction-and discharging it against the second :row of wheel-buckets at the roper angle. The buckets may -in Vaddition to, changing the direction of the stream also act to impart a certain amount of Velocity to the stream.

In Fig. 4 the Wheel-cover and support for the lintermediate bucketsare shown on a*vv .In a construction 'of this kind it is desirable to somewhat-enlarged scale, and -bothv are grooved circumferentially at 18 to further prevent or reduce theleakage atfthe clear.-

ance. Asl the elastic'mo'tivefluid. tends-to escape it lcreates whirls oryeddies in the grooves.

Fig. -shows a sectional bucket-cover developed on a flat pla-ne. vided with ffangesM at-,the edges, whichare Each section is' pros IIO made stiff enough to prevent them from rub- 4 bing onvthe stationar partsA when subjected to fluid-pressure.. T e sections. are perfo. lrated at 19 to receive the bucket-"tenons, and the adjacent'` endsofr the sections are prof "vided with notches '20, Which when the ends" are united form a perforation similar to 19.

.The cover' or fitting or baffiing strip can withl advanta'gebemade outof" fchannelf stockand preferably of steel.

'vv-The baffling ofl the motivev fluid may take lace at ytheside flangesofv the fittingv and afiling stri or cover 13, asshown ingconnecf `tion with vt e'intermediate' bucket-su ports -1 d) strip urpose,*the struc-` 8','or the edges ,O f the flanges on sai may be utilized'for the ture being the A'same in eit er casej" The 'said strip can serve-as a' baffling means on vboth the side and ed e at the same time, as. shown in the upper riglit-handcorner oflilig.- 1 s i The bafiier disclosed 4herein possesses'important advantages `over prior arrangements 1n the Way of Ibetter bathing effects and in the Way Aof v eatly-decreased cost of manufac- 5 r ture. It 1s also well adapted to meet the condition of accidental rubbing of the parts. Aside 'from functioning as a baffler the said, baffle-strip or cover serves to ,-secure `tldieL -outer ends ofthe buckets and form a partf'of xo the passagefor the motive fluid. By making the strips out of solid stock with flanges at right angles thereto it is a simple and inexpensive matter to turn or finish the face or faces to. the required dimensions. Moreover, such a construction renders it vpossible to utilize workmen of ordinary skill. ,v v j It has been .proposed heretofore to use laminated baflling devices forthe free-ends of turbine-buckets, and in some instances the 2o edges of the said devices have been s layed. vThls construction was an objection-a le one for various reasons, chief among which was the difficulty experienced in turning them to a true surface. The thinness of the stock 2 5 and the fact'that the ystructure wasv laminated with the edges separated in aninclined lane made it necessary to tool it very slowly 1n order to prevent tearing or s ringing of the metal, andtherefore requiredP eat care 3o and skill'. With .the structure. ilustrated this objection is overcome, and the parts can be made'sufliciently robust for all practicalv PTPOSGS y In accordance with the provisions of the patent statutes I have described the principle of operation of my invention, together W1th the apparatus which I now consider to re resent the best embodiment thereof; but I esire to have it understood that theappa- 4o ratus shown is only illustrative and that the v inventioncan be carried out in other ways.

What I claim as'new, and desire to secure by Letters Patent ofthe vUnited Statesis- 1. In an elastic-fiuidturbine, the combination of a casing, a means for discharging motive fluid, a wheel, segmental supports mounted on the Wheel having integrallyformed buckets, a cover for the buckets composed of a single layer having a thin central 5o portion and circumferential flanges at the edges, intermediate buckets, and sup orts therefor which are situated in line Wit the flanges and in close proximity thereto.

2. In an elastic-fluid turbine, thecombination 'of a casing, a nozzle, intermediate buckets, a support therefor, a Wheel having buckets, a row of buckets between the nozzle and the intermediates, and a cover f r ythe wheel-buckets having a thin central lfdrtion 6o and circumferential flanges which` project -beyondthe central .portion. and revolve inA close proximity tof the nozzle andthe intermediate support. v

3. In an elastic-fluid'turbine, the combi' flanges,` and means for adjusting the support.,

toward or away from the cover-flanges.

4. In an elastic-fluid turbine, the combi- I nation of a casing, a nozzle mounted thereon and -adjustable in a plane parallelwith the wheel-axis, a bucket-wheel, covers for the buckets having v circumferential Hanges formed integral therewith, intermediate buckets, a support therefor ysituated in line with the flanges, and means for adjusting the support toward or away from the cover-flanges.

v5. Inv an elastic-fluid turbine, the combination of la plurality of wheel-buckets, aA

cover therefor, circumferential flanges -at Aeach side of the cover, intermediatebuckets, a 'support therefor, and a groove opening into the clearance-space between the wheel and intermediate buckets for decreasing the leakage. i

6. In an elastic-fluid turbine, the combilnation of a wheel or support having a plurality of grooved projections Iformed on the periphery, a plurality of buckets, 'each having a shank that enters thegroove, a retaining means for each .bucket which passthrough' a projection and the shank, covers for each row of buckets,-and a row of intermediate buckets located between each two rows of wheel-buckets.

7. A bucket element vforan elastic-fluid turbine comprising a wheel or support with a plurality of buckets attached thereto, and a jointed cover for the buckets comprising a single layer,each section of the cover having a portionv which forms a part ofthe working passage, and integral 'side portions extending at right angles or substantially at right an-A gles thereto for decreasing the leakage.

,8. In an elastic-fluidvturbine, the combination of a casing, a means for discharging motive fluid, buckets which are acted upon by the Huid and are formed integral with their support, a number,v of tenons each formed integral with a bucket, and a cover `for the buckets which is held in place by the IOO IIO

tenons, and has integral'flangesf occu ying planes parallel or substantially paralle with the edges of thel buckets.

'9. In a turbine, the combination, with its drum and' casing, of a numberof turbine-v a blades and aI fitting and baffling strip of channel shape in cross-section, one portion of I which is attached to. the free ends of the blades and the other portion of which .extends at right angles to the turbine-axis.-

10. In a turbine, thecombination, with its drum and cylindrical casing, of a number of turbine-.blades and a fitting and baffling' strip 6 y; nation ofa casing, a nozzle for'discharging made of a single thickness of stock'of channel shape in cross-section, the middle portion ot1` Which extends longitudinally and is attached to the free ends of the blades, and the other 'iro blades and a fitting and baffling stri made of la single thickness of stock of angu ar crosssec-tion, one portion of which is perforated to receive the'blade ends and attachedto the free ends of the blades by riveting over the blade ends which project through the perforations, and the other portion of which extends aWay from the blades transversely of the turbine-axis.l Y,

12. In a turbine, the combination, With its drum and casing, of a number of turbineblades and a fitting and bathing strip divided into 'segmental lengths and made of a single thickness of stock of channel shape in crosssection, the iniddle portion of each segment being perforated and the ends notched to receive the blade ends, thesaid fitting and baffiing strip being attached to the free ends of the blades by riveting over the blade ends which project through the perforations, and the other portions of which extend transversely away from the blades transversely of the turbine-axis.

13. In a turbine, the combination, With its drum and casing, ofy a number' of radial turbine-blades, anda channel-shaped fitting and baffling strip attached to the free ends of the blades and extending at right angles to the turbineaxis,as set forth. i

14. In a turbine, the combination, with its drum and casing, of a number of radial turbine-blades, and a iitting and baiiing strip made of a single thickness of stock and at* tached to the free ends ofthe blades b riveting and extending transversely of t efturbine-axis, as set forth.

-In Witness whereof I have hereunto set my hand this 28th day of April, 1903.

4 e OSCAR JUNGGREN.- Witnesses: y n

L ALEX. F.1MACD0NALD, HELEN ORFORD.

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