US1469965A - Turbine - Google Patents

Description

Oct. 9, 1923, 1,469,965

H. F. SCHMIDT TURBINE Filed July 6. 1921 5 Sheets-Sheet 1 ATTORNEY Get, 9'', 1923.

' H,49,%5 H. F. SCHMIDT TURBINE Filed July 6, 1921 5 Sheets-Sheet 2 INVENTOR Henw Echmdi':

ATTORNEY Get. 9 1923.

H. F. SCHMIDT TURBINE Filed July 6. 1921 5 Sheets-Sheet 4 ATTORNEY Oct. 9 1923.

H. F. SCHMIDT TURBINE Filed July 6. 1921 5 Sheets-Sheet 5 INVENTOR ATTORNEY nanny r. scanner, or swaa'ronn, rnnrvsrnvanm, srenoa 'ro wns'rmeuousa anaemic an]: manurecruame COMPANY, a concession or rnnnsnvanm swarms.

Application filed July 6, 1921. Serial No. 482,768.

and State of Pennsylvania, have invented a new and useful Improvement in Turbines,

of which the following is a specification.

My invention relates to blading for elastlcfluid turbines, more particularly for the lowpressure portions thereof, and it has for its object to provide apparatus of the character designated which shall have a small angle of discharge, adequate discharge area, and high efl'ective blade speed, whereby high efficiency of the blading and the capacity thereof for handling large volumes of elastic fluid are obtained.

Another object of my invention is to pro vide a novel method of expanding elastic fluid by a rotating member so as to provide adequate discharge area and high efficiency of energy abstraction.

A further object of my invention is to provide a reversing or astern section which shall be compact and shall be provided with means to prevent the reversing or astern section from discharging into the ahead sectlon or vice versa.

In the accompanying drawings, Fig. 1 is a sectional view of the low-pressure end of a turbine showing my improved. blading; Fig. 2 is a detail erspective view showing one of my improves blades; Figs. 3 and 4 are sectional views taken along the lines III--III and IV-IV, respectively, of Fig.

1; Fl 5 is a sectional view showing a modified orm of the last-row blading together with. a reversing section, Fig. 6 is a view similar to Fig. 5, but showing another form to of reversing section; Figs. 7 and 8 are detail views of the reversing section used in Fig. 6; Fi 9 is a sectional view taken along the line I IX of Figs. 5 and 6; Fig. 10 is a velocity diagram in which my new blading is compared with the old or existing type; and Figs. 11 to 14, inclusive, are diagrammatic views illustrating certain properties of my construction.

In the design and construction of elasticfluid turbines, in accordance with existing practice, the last row of blades is in neral a com romise, the height being limited by I centri u al stresses, and, with the maximum permissi le blade height, it is necessary to provide large leaving angles for the blades in order to afford sulficient discharge area for the large volumes of low-pressure elastic fluid. Accordingly, I have provided a novel type of bladmg suitable for the last row and which is capab e of passing large volumes of low-pressure, elastic fluid and, at the same time, of preservin small discharge angles, necessary for high I lade efficiency.

Also, the construction of la! e single-unit turbines has disclosed the diculty of excesslve blade speeds due to the necessarily large dla neter at the low-pressure end and to the height of blades necessary to provide sufliclent exit area so that the steam may not be dischar ed with too great residual energy. The reissue patent to Baumann No. 15,092, reissued April 26, 1921, discloses a low-pressure turbine section which is adapted to afford large discharge area with out exceeding safe blade speeds. My improved blading attains this object in a different and simpler way.

More specifically, in moving blades are made relatively wide, aving a width comparable to the height, and are so arranged as tclil receive elastic fillllld axially and to disc arge it erip era or eri herall and laterally. With bladi ng of P y this type, for a given discharge angle, ample discharge area is provided merely by choosing a suitable blade width since the discharge area is equal to the number of blades times the throat width of the nozzle passages between the blades times the effective width or length of a nozzle passage, and. the latter .factor is dependent upon the blade width. The peripher'al discharge is advantageous as the reactive force of the elastic fluld is applied to the blades where the efl'ective speed is higher than the mean speed with ordinary axial-flow blading, thereby resulting in the conversion of a greater portion of the kinetic ener into useful work.

Re erring now to the drawings for a more detailed explanation of my invention, I show a turbine rotor 10, journaled in a suitable casing or cylinder 11, the casing being provided with an exhaust chamber 12 c0mmuni-.

eating with an exhaust outlet 13. Motive or elastic fluid, such as steam, is received in the usual way, is expanded in the stages carried by the rotor and the casing, and is discharged into the exhaust chamber, from nection with a turbine discharging to the atmosphere, although its greatest field of usefulness is in connection with condensing tur-.

bines where large volumes of low-pressure elastic fluid must be handled.

llnFig. 1, I show a plurality of successively arranged sta es 13, 14, 15, and 18, the stage 13 being a apted to receive elastic fluid which has undergone expansion 1n higher presure stages, not shown, and the stage 16 being adapted to discharge into the last, low-pressure stage, comprising a stationary row of blades 17, carried by the casing, and a row of relatively wide blades 18, carried bgyithe rotor. While I have shown the stages 13, 14, 15, and 16 of the reaction type, it will be obvious to those skilled in the art that stages of the impulse or any suitable type might be used. Ordinarily, the axial flow reaction stages would be .used until the safe limit of centrifugal stress for the last row of moving blades thereof is reached, with discharge angles small enough to give good blade efficiency, and then these would be followed b my novel row of wide moving blades which is capable of efficiently handling large volumes of elastic fluid.

The last-row, movin blades 18 are adapted to receive elastic flu1d axially and to dis charge it peripherally or peripherally and laterally. It will be apparent that the peripheral discharge permits of increasing the discharge area, while preserving a small discharge angle, as any suitable width of blade may be selected. 'The blades may be shaped in any suitable way to secure the discharge of elastic fluid in the manner stated to act reactively on the blades.

In Figs 14, inclusive, I show blades 18 curved in radial, axial, and combined radial and axial directions, thereby resulting in cup-like or dish-like blades adapted to receive elastic fluid flowing in an axial direction-between the substantially radial inlet edges 19. The elastic fluid undergoes expansion between the blades and is discharged both peripherally and laterally at high velocity.

It will be obvious that the average distance' of application of the reaction of the elastic fluid to the blades, is nearer the tips than in the conventional type. In the axial-flow type of blade, the mean efl'ective blade speed is taken as the speed of the mid height. In my construction, due to the peifpheral discharge, the average of all points application is nearer the tip of each blade and hence the efi'ective blade speed is higher and a larger portion of the kinetic energy of the elastic fluid may be converted into useful work. As is hereinafter pointed out,

blade speed being that of the tips.

eeaeee if the elastic fluid is discharged wholly peripherally, the effective blade speed is, of course, the tip speed.

As the blades may be made of an desired width to secure an adequate disc arge area, the leaving edges may be made to discharge elastic fluid at a small angle, thereby increasing the blade efliciency.

The blades 18 may be secured to the rotor 10 in any suitable manner, for example, by dovetail connections 20; and, if desired, overhanging tongues 21 for the blades and suitable screws 22 for securin the tongues to the rotor may be provide In Figs. 5 and 6, I show rows of relatively wide blades 25 of a modified form in which the elastic fluid is discharged peripherally, thereby resulting in the effective Each blade preferably comprises an outer hooklike or trough portion 26 and an inner radial portion 27, adapted to be secured to the rotor 10 in any suitable manner, for example v by dovetail connections 28. A section of the blade is shown in Fig. 9. Preferably, each blade is so designed that its center of gravity falls mid-way of the thickness of as set forth in the co-pending application of- Alexander T. Kasley, Ser. No. 486,517,

filedJuly 21, 1921, continued as Ser. No.

521,872, filed December 12, 1921 and assi ned to the Westinghouse Electric and anufacturing Company.

The blades 25 are preferably provided with curved ribs 30 which serve to strengthen the latter as well as to assist in changing the direction of flow of the elastic fluid rom an axial to a radial direction.

The outer edges of the blades are blocked by suitable blocking plate members, 31 in Fig. 5 and 37 in Fig. 6, which assure the peripheral discharge of elastic fluid. .The blocking plate members are secured to the rotors in any suitable manner, for example, by tongue-and groove connections 31; and are preferably secured to the outer edges of the blades. In operation, the blades 25 and the blocking plates 31 and 37 reinforce and assist in supporting each other, this being particularly true when a blocking plate carries reversing blades on one side, as hereinafter described.

Reversing sections or stages of the radialflow type may be associated with the blocking plates 31 and 37, the plates servin as 1,4ee,eec 3 would otherwise occur due to this cause. Also, a reversing section or stage of this type may be incorporated with an ahead section to produce a ver compact and highly eflicient marine tur ine.

In Fig. 5, I show a reversing stage or section of the radial-flow, two-row, multivelocit type which includes concentric rows of bla es of energy abstracting elements 32 and 33 carried by the blocking plate member 31, aforesaid, and between which is located the reversin segment of'stationary blades 34. A suita le nozzle 35 is carried by the casing 11 and discharges motive fluid at high velocity into the first row of moving blades or energy-abstracting elements 32, the energy of the motive fluid being taken out in two steps, namely, in the row of blades or energy-abstracting elements 32 andin the row of blades or energy-abstracting elements 33. It will be obvious that any centrifugal moment, due to the unbalanced masses of the blades or energy-abstracting elements 32 and 33, will be withstood by the relatively wide blades 25 acting as sustaining struts for the other side of the blocking plate 31.

Referring to Figs. 6, 7, and 8,, the c onif struction is the same as that shown in Fig. 5, except for a modified form of reversing element. In Fig. 6, I show a reversin element comprising a single series of inc ined impulse buckets or energy-abstracting elements 38, arranged on one side of the blocking plate 37 with which cooperate the ex panding nozzle 39 and the reversing chamber 40, preferably carried by the upper half of the turbine casing 11, motive fluid being expanded in the nozzle and discharged therefrom at high velocity to act impulsively upon the buckets or energy-abstractin elements 38, and, after passingthroug the latter and having its direction changed, the motive fluid enters the reversing chamber 40, where its direction is again changed, for impingement against the buckets or energy-abstracting elements a second time. In this way, the velocity energy of the motive fluid discharged from the nozzles 39 istaken out in two steps. The passage of motive fluid will be readily understood upon reference to Fig. 8, wherein the arrows indicate the direction of flow of motive fluid from a nozzle to a bucket or energy-abstract- 1 ing element, from the latter to the revers- The feature of providing adequate discharge area will be obvious from a consideration of diagrammatic Fig. 13 which shows in perspective a portion ofa rotor provided with a row of Wide blades 25 having inlet edges 25". Only two of the blades are shown, but it is to be understood that a circumferential series is employed in the bounding circles indicated at b and c. The blades as shown are of the type which are adapted to receive motive fluid between the inlet edges 25', to change the direction of flow thereof between the blades, and to dis-. charge the same radially from curved energy-abstracting portions 26: Assuming that the throat width of an expansion passage defined between the outer curved portions 26 of a pair of adjacent blades 25 is al, then each throat area would be equal to d x e, where e is the blade width.

If the wide blades discharge elastic fluid in an axial direction as well as radially, then to the extent that axial discharge is permitted just to that extent more dis-' charge area is provided in addition to the radial discharge area. Therefore, with blading of the general form indicated in Figs. 1 to a, inclusive, owing to the additional axial discharge area, they may be made relatively narrower than the form of blading indicated in Fig. 13 with the preservation of the same discharge area. It is to be understood, therefore, that the provision of adequate discharge area with any of the forms of blading coming within the purview of my invention involves merely the selection of such a width of blade which will give the necessary total discharge area.

Owing to the fact that considerable latitude in the choice of a width of blade is permissible in accordance with my construc-- tion, the blades ma be made sufficiently wide to provide smal discharge angles and at the same time adequate discharge area. The feature of relatively small discharge an les will be evident from a consideration of ig. 14 which shows in detail two adjacent curved energy-abstracting blade portions 26 which are adapted to discharge elastic fluid peripherally and at an angle. The angle referred to is the angle which the tangent to the outer edge of the concave blade portion makes with the tangent to the circle of the outer blade edge at the discharge tips of the blades. This angle is indicated by the angle a in,Fig. 14, included between the dotted line 7 representin a continuation of the inner discharge sur ace of one of the portions 26 and the line'g which is the tangent to the blade tip circle .at the blade tip referred to.

From the foregoing, the operation of apparatus made in accordance with my invention will be readily understood. Elastic 'fluid, such as steam, is expanded and flows I is found to be 945 feet per second.

will be evident from a consideration of the diagram of Fig. 10, in which a conventional last-row blade having an outlet angle of, for example, 50 is compared, from the standpoint of blade efficiency, with my improved blade having an outlet angle of,for example, 25. Let A0 represent the velocity of elastic fluid leaving a last-row of 50 blades, which, for purposes of illustration, is assumed to be the critical velocity. 1220 feet per second, at one-half pound per square inch absolute pressure, and assume that the mean or effective blade speed OB is 625 feet per second. Solving the trian le AOB, the ineffective or residual velocity B rom the well-known formula, the efficiency of the 50 blades is found to be fluid being discharged at 1220 feet per sec ond, which would correspond to a turbine of 33% greater power, the efficiency of my new blade under the conditions assumed would be 0C CD 1220 630 Due to the higher efficiency of my last-row, low-pressure blading, it is possible to utilize lower steam velocities in apparatus of the same power capacity as the old. For example, assume a turbine with my form of blading having theggame capacity as the turbine having the 50 blades referred to, then since my blading has a greater discharge area for wastes a given diameter, it is not necessary to uti- OE ED 915 390 W W From a consideration of the above, it will be seen that, in the example assumed, my bladi-ng is nearly 100% more efficient than the blading of the old type, which increase of efficiency is due to the possibility of using a smaller discharge angle, adequate discharge area being provided, and to the higher effective blade speed.

To show the efiect of my bladin on the v performance of the complete tur ine, let it be assumed that two turbines of the same capacity are operated under steam conditions, such that a total of 400 B. t. u. are available, and that the turbines are both alikeexcept in the last row of blades. It may be assumed then that the turbine with 50 blades will have an overall efficiency of or would convert 320 B. t. u. into useful work. Now however, the critical velocity corresponds to 30 B. t. n. which, in the turbine with 50 blades, is handled by blades having an efficiency of 40%, that is 12 B. t. u. are actually converted into work, whereas in my turbine these same 30 B. t. u. are handled at an efficiency of something over 80%, or approximately 2% B. t. u. are converted into useful work. Therefore, in my turbine, 320 plus 12, or 332 B. t. u. are converted into useful work, or my turbine is w 320 more efficient than the old turbine.

It is to be understood'that thediagram and the velocity values noted thereon, shown in Fig. 10, are used for illustrative purposes onlyand not in a limiting sense.

It is old, in connection with low pressure blading, to taper the blades by increasing the thickness circumferentially in order to provide sufficient strength for an increase in height necessary to pass large volumes of low-pressure elastic fluid; however, it will be obvious that such tapering is accompanied by a restriction of the outlet or discharge area. On the other hand, with my new type of blading, due to the fact that elastic fluid is discharged at the tips, practically involving as a characteristic the provision of a root connection approximately equal in length to the discharge edges, the blades may be tapered without in any way afiecting the outlet or discharge area. This will be evident from a consideration of Eigs. 11 and 12. In Figure 11, I show hatched outlines or seetions near the roots of blading of the old tapered type and dash line outlines of sections of my improved tapered blading and havingthe same taper. It will be seen that the bladingof the old type is shown in contact at the leavin or outlet side, whereas my new blade having the same inlet pitch and the same degree of taper is uniformly s aced from side to side, due to the fact that t e inner portions of m ranged substantially para lel to the axis of the turbine. In view of the fact that, with blades after they begin to contact at the outlet edges adjacent to the roots; whereas, with blading of my type, the outlet area in no way being afiected by tapering, the height is limited only by practical structural limita-- tions as to tapering:

Fig. 12 shows diagrammatically the possibility of increasing the height of my new form of blade over that possible with the old form, as mentioned in connection with Fig. 11. The moving blades may be made as high as possible, with the preservation of good eficienc-y, and are adapted to discharge elastic fluid for passage through the guide blades 46, and as the latter are carried by the stator, they may, of course, be made much longer than the blades 45. As it is possible to make my new form of blade taller than the old form, the row of blades 47 may be made of an appropriate height to receive the elastic fluid discharged from the guide blades 46.

It will, therefore, be'seen, from a consideration of Figs. 11 and 12, that my new form of bladin may be madefhigher or taller than the o (1 type and maybetapered withoutafiecting the discharge areahf;

Another advanta of my blading the possibilit of building larger turbine units.

As a tur me of the standard type isfniade three forms, it will be obvious to those larger, a limit is reached for which 'itflis capable of discharging low-pressure motive fluid with good efiiciency. lln otheriwords,

as already stated, centrifugal force-imposes a limit on the blade height, and therefore,

blades have to be provided with lar e. outlet angles to accommodate the large vo umes of low-pressure motive fluid. It will, therefore, be seen' that the discharge area provided by the last row of blades is limited in" the old type and is'always less than the area swept by the inlet edges, and this factor serves tolimit'thle practical and economical blades are airsize of a turbine unit. On the other hand,-

with m newform of blade, due to the periphera discharge, the blade Width may be made such thatthe'dischar area is equal to the area swept by the in ct edges of the blades; and, therefore since the discharge area is not a limiting factor to the-same extent, as in existing practice it is possible to build units of larger siae t an heretofore.

It is to be understood that my novel blading may be modified or wherever its use may be desirable. or ex ample the blading maybe applied to the low-pressure ends of a double-flow turbine. Also, bladin principles 0 my invention may 'be-used in a radial-flow turbine, for example the made in accordance with the a plied I Ljungstrom type, it be ng only necessary to v I have the elastic fluid. enter between the blades at the edges thereof nearest the turbme axis andto discharge outwardl and laterally as disclosed in the application of Herbert T. Herr Ser. No. 504,534, filed Sepv tember 30, 1921.

It is obvious that one of the principal features of m invention is the'provision'of adequate disc arge area which in turn is dependent upon the abilit to provide disingfwhich is capableof passing large vol-- umes of low-pressure motive fluid with high blade eiiicienc and at the same time, of utilizing a big effective blade speed; and therefore, I am enabled to roduce a more eflicientturbine, or one, whlch, when compared with a turbine of like power of the old type, is capable of discharging at a lower velocity. Also, I have provided a reversing stage or section which ooacts with my .new form of last-row blades to produce a compact turbine unit and one in which flow from the reversing section to the ahead section or vice verse. is efi'ectively prevented.

While I have shown my invention in but i skilled in the art that it is not so limited, but issusceptible of various other changes and modifications without departing from the spirit thereof, and I desire therefore, that only such limitations shall be placed thereupon as are imposed by the prior art or as are specifically set forth in theappended claims.

' What I claim is 1. An elastic-fluid turbine comprising a plurality .of energy-abstracting. stages through which the elastic fluid flows in the a row of moving blades each having a continuous surface and which are adapted to receive-elastic fluid flowing in the same general-direction from the preceding stagesand to expand and to discharge the same 1n a substantially diflerent direction.

2. An elastic-fluid turbine comprising a plurality of energy-abstracting stages through which the elastic fluid flows 1n the same general direction and a last, low-pressure stage including a row of moving blades each havin a continuous surface and wh ch are adapte to receive elastic fluid -fl ow1ng in the same general direction from the preceding stages and to expand and .to discharge the same in a substantially difl'erent direction.

3. An elastic-fluid turbine compr sing a plurality of energy abstracting Lstages through which the elastic fluid flows 1n the same general direction and a stage lncludmg a row of moving blades each having a continuous surface and which are adapted to receive elastic fluid flowing in the same general direction from the preceding stages discharge of elastic .fluid peripherally at" and to ex and and to discharge the same 'substantia 1y normally to said direction.

4. An elastic-fluid turbine comprising a plurality of axial-flow, energy-abstracting stages and a stage including a row of moving blades each having a continuous surface andwhich are adapted to receive elastic fluid flowing in an axial direction and to expand and to discharge said fluid in a different direction.

5. In an elastic-fluid turbine, the combination of a plurality of axial-flow stages and a last stage having a row of moving blades-which receive elasticfluid flowing in an axial direction and which are curved to provide for the discharge of elastic fluid peripherally at small angles.

6. In a turbine, the combination of a plurality of stages of the axial-flow type and a low-pressure stage adapted to receive elastic fluid from the axial-flow stages and having a row of moving blades curved to provide small. discharge angles peripherally and 50 laterally. I

7. In a turbine, the combination of a plurality of stages of the axial-flow type and a low-pressure stage for receiving elastic fluid discharged from the axial-flow stages and having a moving row of blades which receive elasticfluid flowing in an axial direction and which are curved to provide for the small angles and which are of suficient width to provide a suitable discharge'area.

8 In a turbine, the combination of a plurality of axial-flow stages followed by a lowpressure stage including a .row of blades each having a continuous surface and which are adapted to receive motive fluid axially aeeaeee and-to expand and discharge the same radially and axially.

9. An elastic-fluid turbine stage comprising a row of moving blades each having a continuous surface and which are relatively wide compared to their height, which have their tip and root edges arran ed substantially parallel, and which are a apted to receive elastic fluid laterally and toexpand and discharge the same peripherally.

10. In an elastic-fluid turbine, a last row of moving blades each having a continuous surface and having their roots arranged substantially'parallel to the turbine axis and adapted to expand elastic fluid; and to dis-.

including a row of moviing blades having their roots -arranged substantially parallel to' the turbine, axis and being curved both "radially and longitudinally to provide for the radial and longitudinal discharge of elastic fluid. 1

13. In an elastic-fluid turbine, a lowpressure. stage including a row of moving blades which receive elastic fluid laterally and which are curved to provide peripheral energy-abstracting portions for the discharge of elastic fluid at a small tangential angle.

14.- In an elastic-fluid turbine, a low-pressure stage arranged to receive elastic fluid flowing in an axial direction and including moving blades which are relativel wide compared to their height and which are curved. to provide energy-abstracting portions for the discharge of elastic fluid peripherally at small angles.

15. In an elastic-fluid turbine, a row of peripherally-discharging blades, which receive elastic fluid laterally, which are curved to provide small discharge angles, and which are sufiiclently wide to provide a suitable discharge area.

16. In an elastic-fluid turbine of the axial flow type, a low-pressure row of moving blades having curved portions adapted to discharge elastic fluid axially and radially at small angles.

17. In an elastic-fluid turbine, a row of moving blades each having acontinuous surface,,w.hich blades are adapted to receive elastic-fluid at one side and to discharge the same laterally and peripherally and having such a width that a suitable discharge area maybe provided.

18. In an elastic-fluid turbine, a row of Elm use

' having such a widtlithat. the discharge area may be made at least as great as the area moving blades adapted toreceive elastic fluid at one side and havingcurved portions.

for-discharging the'same peri herally and v swept by the inlet edges of the blades.

19. In ail elastic-fluid turbine, a row of whereby the efl'ective blade speed is the tip speed. I

V 20. In anela'stic-fluid turbine of the axialflow type, a last row of moving blades adapted to receive elastic fluid axially and being curved radially and axially to. provide for the angular discharge of elastic fluid radially and axially.

21. In an elastic-fluid "turbine arow of blades having elastic-fluid disch arge and energy-abstracting portions at the tips, root portions opposite to the' tips and substantially of the same width as the latter, and lateral edges to receive elastio fiuid.

22. In an elastic-fluid turbine, a row of tapering blades having elastic-fluid discharge and energy-abstracting portions at the tips, root portions opposite to the tips and substantially of the same width as the latter, and inlet edges for elastic fluid disposed transversely of the tips and of the root portions.

23. A blade for an elastic-fluid turbine having substantially parallel elastic fluid discharge tip and root edges and an inlet edge disposed transversely of the-first-mentioned edges. l

24. A blade for an elastic-fluid turbine having its inlet edge disposed normally of its root and being curvedto provide a tip discharge edge.

25. A blade for an elastic-fluid turbine having its inlet edge normal to its root and being curved to provide peripheral and lateral discharge edges.

26. A blade for an elastic-fluid turbine curved to provide peripheral and lateral discharge edges arranged to discharge elastic fluid at small angles.

27. A blade for an elastic-fluid turbine having inlet and discharge edges disposed transversely to each other, said inlet and discharge edges having adj acent'extremities.

28. A blade for an elastic-fluid turbine having a root portion and a discharge edge opposite to the root portion which discharge edge has an extremity adjacent to the inlet edg motive fluid at one side and being curved radially and axially to provide radial and axial discharge and energy-abstracting portions.

30. A turbine blade which is substantially e. 29. A turbine blade adapted to receive rectangular in outline. ada ted to receive motive fluid at one side and being curved in charge and energy-abstracting rtions.

31. A turbine blade adapt ,toreceive elastic fluid axiall and being curved to provide for the disc 'ar e thereof atI-a small- I angle and being provided with one-or more .ribs curved fromv an axial toward a radial the directions of its heightiand of its width to provlde height-wise and width-wise disdirection to guide the elastic fluid and to strengthen the blade.

I 32. A turbne blade having a width which approximates its height and being provided with a lateral inlet edge and be ng curved to provide aperip 'ral portion arranged to discharge elastic uid at a small angle.

33. In an elastic-fluid turbine, a row of blades tapered'from the roots toward the ing the directionof the elastic fluid from an axial-to a radial direction.

35. In an axial-flow turbine, the combina tion-of a last low-pressure stage including a moving row of blades which are adapted 'to receive elastic fluidflowing in. an axial direction and to discharge it peripherally and a reversing radial-flow stage arranged at the outer edge of the moving blades of said low-pressure stage;

- 36. In a turbine having a plurality of axial-flow stages,vthe combination of a lowpressure stage having a row of moving blades adapted to receive axially flowing elastic fluid and to discharge it peripherally,

said moving blades being curved to provide small discharge angles, means-for blocking the outer edges 'ofthe moving blades, and

a reversing radial-flow stage having the moving energy-abstracting elements thereof carried by said blocking means, I

37 In a multi-stage turbine, the combination of alow-pressure stage having moving blade structure adapted to receiveelastic fluid flowing in an axial direction and a reversing radial-flow stage having the moving blades thereof supported by said blade structure.

38. In a turbine having a plurality of stages, the combination-of a last low-pressure stage including a row of relatively wide moving blades receiving motive fluid axiallyand discharging it peripherally, blocking means for the outer edges of the wide blades,

and reversing energy-abstracting elements carried by the blocking means.

'39. In a turbine having a plurality of stages, the combination of a last low-pressure stage includin a row tr relatively wide moving blades, 21 apted to receive motive and to discharge it peripherally, rein orcin of the wide bla es, and reversing energy abstracting elements carried by thereintorcing means.

40. In a turbine havin a plurality of stages, the combination 0 a last low-pres sure stage including a row of relatively wide moving blades adapted to receive motive fluid axially and to discharge it peripherally, blocking means for the outer edge-s of the wide blades, and radial-flow reversing energy-abstracting elements carried by the blocking means.

41. In a turbine having a plurality of stages, the combination of .a last low-pressure stage including a row of relatively wide moving blades adapted to receive motive fluid axially and to discharge it peripherally, blocking means for the outer edge of the wide blades, and radial-flow reversing energy-abstracting elements carried by the blocking means, said Wide blades serving to resist deflection of blocking means due to centrifugal eflects.

42. In a elastic-fluid turbine having a casing, a rotor, and a plurality of stages carried thereby, the combination of a last stage adapted to receive fluid axially and to discharge it peripherally, means for blocking the outer edges of the moving blades, and a reversing element comprising lateral buckets carried by the blocking means and a nozzle and a reversing chamber carried by the casing and cooperating with the buckets.

43. In an elastic-fluid turbine having a eeaeee casing, a rotor, and a plurality of stages carried thereby, the combination of a last 'stae ada ted to receive elastic fluid axially I an to dlscharge it peripherally comprising relatively wide moving blades, means for blocking the outer edges of the moving blades, lateral buckets carried by the blocking means, and a nozzle and reversing chamber carried by the casing and cooperating with the buckets.

4:42. In an elastic-fluid turbine, the combination of an ahead section, a reversing section, and a plate member to prevent discharge from one section into the other, the energy-abstracting elements of the reversing section being carried b the plate member.

45. In an elastic-fluid turbine, the combi nation of an ahead section, a radial-flow reversing section, a plate member between the sections to prevent flow from one section into the other, and supporting the energyrabstracting elements of the reversing section.

46. In an elastic-fluid turbine, the combination ofan ahead section adapted to expand elastic fluid axially and finally radially,

a radial-flowi reversing section comprising movingbuekets and a cooperating statlonary nozzle and reversing chamber, 'a plate member between the sections to prevent flow from one into the other and carrying the buckets, and a cylinder upper portion or cover carrying the nozzle and reversing chamber, whereby the upper portion or cover, with the nozzle and reversing chamber, may be readily removed.

In testimony whereof, I have hereunto subscribed my name this 30th day of June,

HENRY F'SCI-IMIDI.

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