US986368A - Elastic-fluid turbine. - Google Patents

Description

O. G. CURTIS.

. ELASTIG FLUID TURBINE.

APPLIGATION FILED AUG. 1, 1907.

Patented Mar. 7, 191-1.

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ELASTIC FLUID TURBINE.

APPLIGATIDH FILED AUG. 1, 1907. 986,368, Patented Mar. 7, 1911.

Witnesses? *mveiitm' A ttornej's.

UNITED; STATES PATENT orrron.

CHARLES G. CURTIS, OF NEW YORK, N'. Y., ASSIGNOR, BY MESNE ASSIGNMENTS, TO v GENERAL ELECTRIC COMPANY, A CORPORATION OF NEW TORT nL'As'rIcrLnIn r mnmn Specification of Letters Patent.

Patented Mar, '7, 1911.

Original application filed January 19, 1898, Serial No. 667,144. Divided and this application filed August 1.

1907. Serial No. 385.522.

To all. whom ct may concern:

Be it known that I, C ARLES G. CURTIS, acitizen of the United States, residing at New York city, in the county and State of New York, have invented a certain new and useful Improvement in Elastic-FluidTu-rblues, of which the following is a specificalion. i

This is a division of my application for tturbinewheel. by a nozzle as a stream with any desired portion of its original energy converted into his rim within certain limits. If the flow of the steam through the working passage of theturbine is accompanied by-a stress upon surfaces thereof properly arranged and designed, mechanical, rotation of the apparatus and utilization of the fiuids energy Will be bed. has been attained by making the movable elements of the working passage in the form of a curve concave toward the direction of rotation, and the centrifugal force of the particles (as the direction of their flow has 4 thereby been changed) has been relied upon to cause the desired rotative stress or dIIV ln water turbines this method ing effort. of utilizin '-tl1c. Wis win-c of the stream 'is very satisfactory, the power {developed on the shaft b'oing"a very large percentage of the amount, which theory would indicate as possible, in view of the a11gles,vel0citics,etc;, ivhilc in steam or other elastic fluid turbines, a much smaller percentage of the corresponding amount has heretofore been obta ned. 'This is believed to be due, in part at least, to the current. misconception.that

' an elastic fluid having-- a considerable m's yni'va may be treated as Water, an inelastic fluid, and utilized in a turbine in the manner which has been found satisfactory lnt'watel turbine practice.

' Comparing a reciprocating steam engine Heretofore this result.

' and a steam turbine, thefiylinder wall. losses, as well as the mechanical friction of the one, are substantially eliminated in the other,

and there appears to be no sufiicicnt reason why a properly designed steam turbine should not be a much more efficient utilizer of steam energy than a reciprocating engine. One reason at least, for-the failure to obtain the very greatly improved econom referred to, is believed to be due to the faiure heretofore to providefor the steam or the nature of the fluid.

An'incompressible fluid entering a curved vane passage at any given velocity flows through it in a stream of uniform density and sweepin conditions Wlll maintain a stress upon the elastic fluid,-aworking passage adapted to concave walls, each layer of particles press around its curve under like i'ng upon but not compressing the layer ad-' jacent to it toward the concavity, and will, issue therefrom in a solid stream of uniform and unchanged density (except asfriction may cause eddies) but at a reduced absolute velocity. An elastic fluidentering such a passage at an enormously higher relocity and undergoing a cl iange of direction of flow,"

will exert a stress by centrifugal force at the points of change, but; as the fluid is'compres siblc the stress of each layer of fluid upon the layer adjacent to it'will compress the latter and the density of the stream will no longer be uniform over any. given cross-see tion.

as?! It will be greaterfat the concave surface where the rotative stressis exerted on the- Wall of the passage, and least atthe edge of the stream farthest removed their from. An analysis of this phenon'ienon of centrifugal compression shows that the 00111- pression can only be-obtained by a conversion of his 'vz'va "into pressure; or in other words, by a sacrifice of the velocity of flow,

and under conditions such as would he found in practical cases, the energy thus transformed into pressure is avery considmnblc portion of the total energy in the fluid. These facts have not been appreciated'here- -tofore, and the buckctsor vane passages of elastr fluid turbineshave been-heretofore.

designed to operate on-Fthc same general principles in th s respc'ct as those of water .turbincs. This is a serious mistake, since was the 02's viva thus necessarily converted into pressure may readily be wasted b re-ex'pam sion of the fluid under con itions not adapted to insure the due restoration of "via vital, and. unless the due restoration of via m'oa and. utilization thereof is had, the efiicienc of the turbine is unnecessarily reduce As usually designed for use with an elast-iefiuid, the curved vane passage of waterturbinepractice has from this point of view peculiar advantages. The centrifugal stress causing rotation is all upon one side of the passage, and the compression thus localized is great, whilethe conservation of this pressure and the due restoration ofmz's m'va thereafter'is, if not impossible, at least, attended with unnecessary difiiculty. The tendency to eddy currents and frictional re-' tardation is also great, and the unnecessarily large variation in density over any givencross sectlonal area complexifies the whole problem.

I have devised a new principle of bucket- I action applicable toan elastic fluid whereby go co'nvcrsionfrom m's m'va into pressure a stream of such fluid may be used in a work without substantial choking (or change in the quantity flowing per second), providedthecontraction of the passage is not too great, and the fluid will be found at the successive cross-sectionsat the pressures, volumes andvelocities corresponding to such conversion. If such a passage is free t o move in the direction of the flow of the fluid, the stress'upon theconverging walls Wlll drive it forward. This principle of bucket action may be superimposed upon the old principle of such action by centrifugal force on a curve, but in its more simple or elementary form it' consists in delivering "the stream of fluid (preferably at a higli veloity "and low pressure) into a" movable vane element, forming the wnole or a part of the Working passage, and Whose-axial line in, its anterior fluids direction of towe- "-Two ornioreot' the walls of tlus'portion. however, converge,

decreasing the cross-sectional area in the di-' ,recti'on otflow to'a minimum cross-section sutlicicnt to tarry, the fluid, without choking,

at the volume and therel'ocity correspond-' ing toa pressure equal. to thatwhich the virtual vi.s'-,m'v;a1is capable of causing in; such a passage without substantial interrup- [ion ofllow. In this converging anterior portion is that of the" portion the ma viva wiitHwhich the flat" entered the passage is into ressure, its" assage from pointto point ei'ng attende by progre ije deelii lg in velocity and increase-'iin i'pressure. e axial .line of this anteriorsportion'fiifthe. movable element bein at an acute angle to; the direction of rotat1on,any stress eaerted" upon the converging surfaces tthereq f; will tend to rotate the apparatus The fl idydm: livered in this way to the'paSsage, impinges upon converging opposing surfecesandthe argely reconverted r'otative stress. is thus had, not on; one curv'ed surface only, but on-twoor more s 1des of thestreainandunderconditions insuring its more uniform density, a'nd'a certain reeovcry of the ener y'converted into pressure;

sothat it'may't 'ereafter' be utilized.v The:

rate of fiow' at each point will be the samef the cross-sectional area .atall points being such as to carr the weight of fluid deliv- 'ered per secon" to the passage, at the velocities, volumes andpressures at the several points.

The fluid might issue from the movable elementinto the exhaust, or into a station ary element at this point, but this is not the, preferable plan, nor would the whole principle ofbucket 'action thus be shown. garding the description, so far as relating to the bucket action inthe anterior portion,

of themovable element, what follows: 1'8.

lates to the bucket action in the'midd-le and posterior portions ofthe movable element. The fluid enters the iniddle' portion through the funnel throat ofthe anterior portion under a desired pressure (but not exceeding the maximum as indicated) and at a corresponding velocity and uolume, the velocity being, however, relatively low in a y case. The middle" portion may be at .her a. curved passage adapted to turn the IKtream through the desired change of angle t a relatively'low velocity, subjected to a relatively small centrifugal compression, 'frictional retardation and eddy currents,;:as

disclosed 'and specifically claimed in my ap plication for patent, Serial No. 667 ,144, or. the'stream may enter an enlarged chamber, in which substantially all of its remaining as m'gm will ,.be converted into pressure.

In either case" the outlet for the fluid,

whether fromsuch curved ortion or from such enlarged chamber, wi l 'b e;through' posteriorportion of the movable element \Whose first cross-sectional area will, be such 'as to carry the fluid or permit its e'sbape at the pressure, volume and '.velocity there existi ug. This posterior portion willprefer- '-'a =bly' have walls divergingiin the di ectio'n of:fiow and an axial angle asobtuse'as pos- .sible to the plane ofrotation, and'at any rate, such asthat the largestcross-sectional area of the posteriorjportion shall be in the I genera-h direction opposl-t e to that-of rotation.

season In this posterior portion of the mova 1e elementthe fluid will expand and have its remaining energy converted into am to the extent permitted by the increase of cross-sectional area. of the passage, its flow from point to point being accompanied by a progressive increase of velocity and decline in pressure. As in the anterior portion, so in this posterior por ion the stress upon surfaces converging toward the dircction of rotation Will vbe a rotative stress whereby the energy of the fluid'will be converted into mechanical power.

\Vhile I prefer to produce the maximum conversion of Ms aim. into pressure in the anterior portion of the vane space, any dc gree of such conversion is advantageous, and is within the scope of my present invcu lion.

At the discharge end of this posterior portion of the movable element, the fluid should preferably be at a low pressure and high virtual velocity. It not then dis-- charg'cd into the exhaust, it will be received by an oppositely rotating element or into a. stationary clci'ncnt, and after having its di rcction of how changed, be delivered to a, subsequent clement, etc. The number elements may be few or many in number, according), to their peripheral speed and the degree of efliciency desired. I

My invention is also applicable to a stationary intermediate elenicnt in the Working passage in which the fluids direction of flow is changed. Such change being necessarily accompanied by compression, eddy currents, frictional retardation, etc, it is as important to conserve the energy thus necessarily converted from his aim into. pressure and to reconvert it into "02's via/. under conditions insuring due restoration thereof in the stationary in the movable elements. It will be observed that the principle of bucketaction thus described may be combined .With the older and usual one, by providing in the anterior portion a concave surface together with the other converging surfaces, and such a nmde of operation may give improved eiia-icncy as compared With the usual method. The dcnsity of thefluid Will be more uniform and the energy converted into pressure by centrifugal. compression will be 11'101'0 larg'cly conscrved and utilized after due rcstoration of 1117's 'm'ra had. In combining the two methods as above, it will be desirable to have the greater amount of change of direction take place a 'ter the velocity of the stream has been very considerably reduced in such a contracting portion (it tho vane passage. as is indicated-above. I do not intcnd to limit the scope of my invention in thi respect, hoi'vcvcr.

Rail-5'1 inn now to the more simple or clei muuary form of the ucw principle of bucket action above described and to the movable element as a Whole (comprising; anterior, middle and posterior portions) the stress of the hind upon the surfaces at the passage at various points may be favorable or un favorable to its rotation, or neutral. A substantial preponderance of stress favorable. -to rotation is obtamed, however, and the middle portion, Whether in the form of an enlarged chamber or not, Wlll contribute thereto, for even if this portion is not of the curved type but comprises a large reservoir or chamber, the stress of the fluid therein will be exerted upon an area of surface in the direction of rotation greater than that of the back yvall, so that even if the maximum pressure Which can be had at any point therein were assumed to exist at all points, a portion of the energy of the fluid would be utilized therein. The fact that zones ofgradually increasing pressure must be found near the discharge end oFthe an terior portion, and zones or" gradually diminishing pressure must be "found near the delivery end of the posterior port-ion of the passage respectively, it the fluids flow is to continue Without choking (that is to say. without change in the quantity flowing per second) insures a greater utilization of energy than vould be found under the conditions assumed in the Preceding sentence.

The principle of bucket action herein described is not applicable to incompressible fluid turbines. If the attempt were made to operate such a turbine as is herein described with an inelastic, incrmiprcssible fluid, such as Water, the-action of the fluid. in it would be essentially different from that of an elastic-fluid. Water cnterino a properly designed contracting passage under a given velocity will reach a. maximum vclocity at the point of greatest contraction;

and this velocity will be that due to its hydrostatic head. Such a passage will choke the flow (that is to say, rcdu e the quantity flowing per second) if the flu d clitcrs it at this maximum velocity due to its head, and a fter this choking has established a reduced rate or flow, it will be found that at the orifice, or receiving end ot' the contracting passage, the velocity of the stream is les and its hydrostatic head gri-uitci', while as the contracted end is approzn'hcd thov hydrostatic head decreases and the vclocity increases. On the contrary, with an .clastic fluid T have found that the effect of cont action of the 'iassago, it not carriedvtoo far, will be to convcrt M's /H l(/. into prcssure Without cau ing any choking (that is to say. rcdurtion of quantity flowing per-sccoml). The fact stated above as to the action of wa eriloiving through a crmtrzu'ting passage has been Well known and has b en relic-d on in (in design and construction of \vatcr turbine nozzles, wherein a velocity of discharge equal to that. due to the hydrostatic head desired. The reversibilit ofthe action with j In the accompanying drawings forming a art here'pf, Figural is a horizontal section glustratin'g two vane spaces embodying my present invention. Fig. '2 is a vertical section through the,central-line of one of the i5. vane spaces of Fig. 1 showing slightly diverging top and bottom walls.- Fig. 3 is a sectlon similar to Fig. 2, showing a'difi'erent' arrangementof the top and bottom walls of the vane spaces of Fig. 1; Fig. 4 is a horizontal section of my improved buckets, illustrating the same general form as in Fig. 1, but having. theposterior portions of the vane "spaces placed at a greater angle. Fig. 5 is a vertical section through the central. line of one of the vane spaces of Fig. 4, illustrating a'parallel disposition ofthe top and bottom walls of the vane s ace. Fig. 6 is a horizon tal development 0 the nozzle, and a part of the buckets of a turbine having two sets of 3 .movable buckets and one set of intermediate stationary buckets involving my invention.

- Fig. 7 is a viewillustrating the top and bottomwalls of one line of vane spaces in the turbine of Fi 6. Fig. 8 is ahorizontal section illustrating two of my improved vane spaces of a modified form, and adapted to a relatively high bucket velocity as compared to the velocity of the fluid. Fig. 9 is a view illustrating the top and bottom walls of one of the vane spaces of Fig. 8. Fig. 10 is a view illustrating the application of my improved vane spaces to the case of a turbine comprising two sets of buckets moving in' opposite directions, the first set of buckets discharging directlyJinto the second set of buckets. Fig. 11 is a top .view of aportion of the turbine wheel partlybroken away to illustrate two of the vane spaces and showing a method of construction by which my improved vane spaces can be cheaply and effectively constructed. Fig. 12 is a vertical section on the line 1212 of Fig. 11, looking in' the direction of the arrows crossing that line. Fig. 13 is a view of the inner face of the ring carrying the forwardly projecting portions of the vane spaces, the opening to one vane space being shown and the vane space itself being developed in dotted lines. Fig. Mrepresents a modified form of the figures shown in Figs. 12 and 13, showing in section one of the vane spaces in one of the rings. 1 Fig. 15 is a section through the throat of the portion of vane space shown in Fig. 14, illustrating a round throat of a diameter equal to the depth of the vane If space, and the dotted lines showing the rectangular form at the other end of the vane space. V

In my improved bucket shown in. Fig. 1, the anterior portion of the vane space f has a diminishing cross-sectional area in the direction of flow and converts to.a greater or less extent the en's rind of the elastic fluid into pressure, the degree of conversion being determined by the size of the contracted in-' ner end or throat g 0 this portion. The posterior portion h of t e vane space has an enlarging cross-sectional area, due to the divergence of all its walls, and a throat z'.. The throats g and i enter and leave the central enlarged space or reservoir 7c in which 7 the ms'o'i'va of the elastic fluid is still further or wholly converted into pressure during the change of'direction o'fflow and under conditions which insure the due res- .toration of via viva in the posterior portion. The relation between, the cross-sec tion at g and i must be such as not to cause choking or interruption of flow, having regard to the pressures, volumes and velocities there existing, and to the utilized and wasted energy. The stress upon the converging side walls of the anterior portion f of the vane space tends to drive the buckets forward and a similar effect is produced by the stress upon the diverging walls of the posterior portion-h ofthe vane space.

In order to obtain desired cross-sectional area at the throat i, as compared with that of threat g, whetherequal, greater or less, the top and bottom walls of the vane s ace may diverge more or less, as illustrate in Figs. 2 and 3, orthey may be parallel orconverge. r

In Fig. 4 a form of bucket similar to that of Fig. 1 is illustrated, but an Enlargement of the throat i is secured by giving the p05- tcrior portion of the vane space a greater f angle, in which case the top and bottom. walls of the vane space may be parallel, asillustrated in Fig.5.

In Fig. 6 is illustrated a compound tur .sur'e being converted into pie vi'vain the vane spaces of the turbine. Since the vane spaces of each set, as shown in Fig. 6, have the Hlll'lt! angle at their receiving and dis rhurgiug ends, enlargement of cross-sect ioual area at various poiutsmay he had by vary-- ing the vertical dimension or bucketdepth, and this may he had by :1 (iii e 'r'ence lit the top and bottom walls of the time s; iLitf-i as illustrated in liig. 7.

llly improved buckets are applicable to compound turbines having any number of movable or statimiary eleu'i'ents, or to such turbines of the jet type in which the fluid is pas ed through the same set of buckets two the actual morenreut of the steam particles in the vane spaces relative to the movement;

I he represented by the line u g, which is par-- allel to the axis of the throat {1.

of the vane spaces, themselves this complex action being analyzed by the diagram shown in dotted lines. The elastic fluid enters the vane-space with the velocity in o. The velocity of the bucket is m '11-. here-fore u 0 represents the virtual angle at which the fluid enters the. vane space. While the fluid passes through the anterior portion of the passage its velocity becomes reduced, and when it reaches the throat g, its'velocity,. for example, will be represented by-the length m 9.. The. virtual angle of flow will therefore Between the receiving end oi the anterlor portion and its throatthe'virtual angle of inflow will gradually change so that the true theoretical shape of this portion should be more or less curvedydepending upon the change in .velocity of the -fll11d produced by the contracting passage, and a so upon the relative eiples.

Velocities of the fluid and that of the worable buckets. Similarly the posterior port ions should theoretically be given a curved form, as shown in Fig. 8, the change of direction being Worked out-on similar prin- The construction illustrated by this figure may be used without the central reservoir 7c, and with the curved middle portion of thevaue space having parallel front and rear walls.

It. can 'also be used with a; construction wherein the posterior portion of the vane space has parallel front and rear walls. Due to. the sharper or less angle of the posterior portions of the vane spaces, a

' considerable increase in the depthor verti- \"ul dimeusionin the middle portions of the ,vane spaces is necessary, as illustrated in 'that in which it would turn it used as a motor and at a proper speed relative to the amount of compression or the velocity of 'tlovv whi h it is d'e-dred to obtain. the effect (if-these buckets will he to draw the air or other elaslir fluid into their anterior portions. producing uon'ipression of the fluid therein in' the gradually diminishing crosssection of these portions and then while such fluid is under increased pressure and reduced veh'a-ity. changing its direction of flow as desired and delivering it either by means of parallel or diver ing.walled pusterior portions which solve to convert pressure into velocity tothc stationary or receiving portions of the um'mratus Wherein the oak elem may either be preserved as velocity or' converted into the required pressure as desired.

In Fig. 10 two turhiuewhee'ls ll and G are illustrated. rotating in opposite directions. the vane spaces of the-wheel F discharging: directly into the vane spaces of the wheel t}. This figure simply illustrates the fact: that my improved prinril'ile of bucket aetioi'i is applicable to turbines of this character.

lu Figs. 11;. 12 and t2? a desirable construction for my improved form of bucket is illustrated. H and l are two steel rings which are riveted togetlu-r and may be mounted upon any portion of the turbine 'ivheel. for example. the disk K, or one section of it. by incans-otthe flanges 'r' and 8.

There steel rings are cut with suitable tools no as to form the vane spaces, one partof the vane spaces being formed in each ring and the vane spaces being completed. by the joining! of the rings. struetion the central reservoir in, when employed. may be formed partlyby radial en- .largemcnt of the passage.

The construction avoids the necessity for the use of outer With this conandinner rings between which the buckets are secured, as employed by me in former t constructions.-

to avoid confusion; h

It isevident, as already 'mdlcated, that -I also intend to use. my improved buckets In Fig. 13' .only one the openings through the ring H is illustrated 1n order and principle of bucket action, both for -10 and wherever the direction of flow of an i claimed herein nbut will be made the-sub tiorr is included in the claimswhich I make in described as applicableto a turbine using compressing air or other elastic-fluid laid for imparting velocity to them,' by a re-f versal of the operation, and I wish' it-understood that this reversal of the operaherein to the resent invention.

It will be servedthat the method herean elastic fluid, is-also applicable whenever elastic fluid moving under a considerable velocity due to its *v'is owa, is to be changed. I. intend to apply. for, a patent or patents onits 'usein connection with other kinds ofapparatus.

to have understood that the apparauis shown ismerely illttstrntive and that theinvention can be carried out 111 other ways.

Having-now described my ill\GI]tl01'1,Whflh I claim as new and desire to secure by Letters Patent, is: 1. An elastic fluid turbine of the axial flow type, having an annular opemng and. buckets disposed therein, the said opening V having a contracted inlet and a contracted outlet. I

2. In an elastic fluid turbine a turbine wheel provided at its periphery with two rings each carrying a portion of each vane space and completing the vane spaces when they are attached together, snhstnntially as set forth.

This specification signed and witnessed this 30th day of July, 1907.

CHARLES CURTIS.

\Y'itncsses IH'IOXARI) H. Dyna, .TonN L, Lo-rscn.

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