US1793468A - Turbine blade - Google Patents

Description

Feb. 24, 1931. B. v. DENSMORE 7 1,793,468

BA! DENSMORE BY cu. 05, M

ATTORNEY mon center.

7 Patented Feb. 24, 1931 BENJAMIN v. nnnslvronn, or Br anna/inertia,rnnlvsyrvnnrn, Assrenon T WESTING- rronsn ELECTRIG & nannraorunrne oonranv, A oonronnrron or rnnnsvnfvaivm.

. iA ppl ication filed May28, 1929.;sria1'1vo. 366,618;

. My invention relates to an elastic fluid turbine, more particularly to the blading thereof,

and it has for an object to provide an improved construction-of blading. 1 V

. .More particularly, my invention relates to turbine blades of the side entry type in which v the root portions are curved to conform in a general Way to the curvature of the blade, for

- turbine the purpose of providing increased strength 19 with minimum spacerequireme'nts, as fully set forth in the copending application of Goldie Back, Serial No. 219,485,1iled September 14, 1927 patented July 2, 1929, No. 1,719,415, and assigned to theVVestinghouse Electric 8: Manufacturing Company. In the construction described in the above -mentioned application, the rotor is formed like a disc with transverse, serrated retaining grooves or slots of curved form and the roots oftheblades are'properly shaped to fit 1nto these curved retaining grooves. Theblades are secured against radial movement by the interfitting serrations inthe side walls of the grooves and the roots, respectively.

I A particular object of my 1I1V6I1l31011 1 to provide means for bracing the blades against each'other adjacent the root port ons, and thus to provide a more rugged type of bladin'g construction; p Y A further object is to provide means for locking the blades in their retaining grooves against axial movement, that is, movement lengthwiseof the groove;-

In accordance with my invention, the base portions of the respective blades are provided with buttress-like enlargements having arcuate side walls, the 'side'walls'of each enlargement being adapted to abut the side walls of the next adjacent enlargement in such a manner as to brace the bladesagainst movement lengthwise of their" retaining grooves. The sidewalls of the enlargements are so: formed that with one blade mounted in place,the next adjacent blade can beinserted .without interference .of the adj acent side grooves, this being preferably accomplished by forming the said adjacent side walls of the enlargements and the sides of the root portion'of said next adjacentblade about "a com These enlargements thus serve anna amps the'dual purpose of strengthening the blades and of locking them in the rotor.

Theabove and other objects are effected by.

my invention, as will be apparent from the following description and claims taken in.

connection with the accompanying drawings,

forming a part ofthis application, in which:

F 1g. 1 is a perspective view offa p'ortion'of a place Fig. 2 is a section on the line I'III of Fig. 1;and,

Fig. ,3 is a section on the line 111411 of Fig. 2. r In the drawing, I show a turbine rotor in the form of a disc, indicated generally, at 10 in Fig. 1, and fitted with a number of blades 11 arranged 'ina row about the periphery of the rotor. The blades ll are provided with root portions 12, which are curved transversely, or in the direction of fluid flow, to conform in a general way to the curvature of the blades, and which are provided with serrations 13 adapted to interlockwith serrations it formed in the sidewalls of the transverse retaining grooves 16. grooves are, of course, curved similarly to the root portions. 'The serrations '13 and 14,

therefore, serve to restrain the blades from moving radially in'their'respective grooves.

In this type of construction, the curved root portion follows approximately the curyature of'the' blade section so-that the blade is directly over its anchoring projection, or

root portion and hence,the bending stresses are greatly reducedand a relatively strong andcompact anchorage is provided. 7

In order to 'provide for bracing and strengthening such blades at their base portions and to provide for locking the respective blades against movement lengthwise of the respective retaining grooves, I have provided buttress like enlargements 17 on the base portions of the respective blades, and these enlargements have arcuate side walls, the curvature ofwhich is similarto that of the retaining grooves. Each enlargement has a concave side Wall 18 and a convex side wall 119-, the-concave side wall'of each en- .largementbeing adapted to abutthe lVQK. M

rotor, showing some of the blades in.

These retaining.

side wall of the enlargement of the next ad-. jacent blade, and, due to the curvature of" therespective side walls, to lock the blades against axial'movement. w a

This will be more apparent from a consideration of Fig, 2, wherein the, convex side wall19 of the enlargement 17,:is shown as an are described about the center 21 and haw ing a radius B. As shown] in this figure, the center 21 falls upon the line AB which is parallel to the side or the rotor disc 10, and intermediate the axial extent of the enlarge ments. 7 For convenience, the 1n Flg. 2 have been designated as 17,17 and 17 respectively. The convex sidewall 19 of the enlargements 17 obviously must have the same curvatureas thejuxtapesed, concave side wall 18 of the adjacentenlargement'lz", for otherwisefltwould not be possible to slide the enlargement 17 past the enlargement 17 in inserting the blades into their respective. slots in the rotor. from the center 21, along the line AB. a 'distance equal to the maximum thickness of the enlargement 17 is the center'22 about which the convex side wall 19 of the enlargement 17 is formed as an are having the same radius R. Likewise, the concave side wall of the next enlargement 17 is formed in a similar manner with the same-radius about thesame center.

Considering theenlargement 17, it will'be seen that-as the op'positeside walls of this enlargement are formed as arcs having the same radius of curvature,"but having difi'er ent centers, this enlargement must have its ma-ximum thickness circumferentially of the rotor on the line AB as designated by the dimension L. Since, ifthe arc forming the convex side wall. 19 of the enlargement 17 be completed to a circle, then this circlemust necessarily intersect a circle formed in the same manner by extending the concave side wall of the same enlargement Since'these circles intersect each other,'it follows that the adjacent arcs of these circles nust approach each other. Hence, these enlargements have a greater thickness in their. central portions than at the sides thereof, and the dimension L will always be greater than either the dimension M, or the dimension N, which indicate the respective thlcknesses of the enlargements at the end portions thereof. Furthermore, as the curvature of the adjacent side walls of the respective enlargements is the same in each case, it will beapparent that the blades may he slid into their respective grooves, one at a time, and that each blade will 'be locked-in place between the enlargements oft-he adjacent blades.-

As'will be observed from a consideration of the above, the curvature of the root portions ancllthe' grooves must be so related to curvature of the enlargement; asto. permit enlargements shown Spaced each blade to be inserted after one of the adjacent blades has been inserted without interfering therewith. Apreferred manner of accomplishing this is to form the sides of the root portion and the groove and one side ofthe'enlargement of each blade about a common center; the other side of the enlargement being formed to contact with the enlargement adjacent thereto, that is, about the center of curvature of the adjacent root portion and groove, which is spaced a distance equal tothe pitch of theblades at the enlarged portions.

This-will be apparent from Fig. 2, wherein the dotted lines 24 and 25, are meant to indicate that the sides of the root portion and the groove associated with the-enlargement 17 are formed about the center 21, which is the center-of curvature of the concave side wall 18 of-the enlargement 17. It will thus bejapparent that the blade having the en- ..largement 17, maybe inserted atter the blade having the enlargement 17 is in place, andsthat the concave side wall 18 of the former will slide along the convex side wall 19 of the latter. V

Any suitable provision may be made for the ln's'ertion of the last blade. For example,

if the blade 17" is the last to be inserted,

the convex side wall 19 thereof may be. relieved along a curved; surface whose center is the center 22,,as indicated by the line 26, to provide a maximum thickness equal to the dimension N. This permits the convex side of the enlargement 17. to pass the corner 27 of the adjacent enlargement The enlargement Y17'. and its associated root portion may then be secured against movement transversely ofthe rotor in any suitable manner, as by caulking or pee'nin'g the root portion.

I From the above description, it will be seen that I have providedinterlocking enlargements for blades of the character set forth, which look the blades in the grooves and which brace the blades against each other,

1. The combination of a rotordischa ving.

b1ade=holding grooves disposed transversely of its periphery, and bladshaifing :rootportions secured in the grooves and provided with enlargementsabuttin each other along curved surfaces;

my invention in but Q images 2. The combination of a rotor having a row of curved blade-holding grooves, the grooves extending transversely of the row, and bladeshavingreurved rbot portions secured in the grooves and provided with enlargements abutting each other alongcurved 7 surfaces.

3. In a turbine, the combination of a rotor, a row of blades, means providing forthe attachment and detachment of the blades by lateral movement thereof relative to the rotor, and interfitting enlargements carried by the blades, each enlargement having contact surfaces which are convex and concave in a direction transverse of the rotor and the convex and concave surfaces of each enlargement having spaced centers of curvature.

at. In a fluid motor, a rotor and arrow of blades mounted thereon, said blades having root portions and enlarged portions intermediate the blades and the root portions, the opposite sidesof each enlarged portion being formed along arcuate surfaces whose centers are spaced, circumferentia-lly .of the rotor, a distance equal to the pitch of the blades at the enlarged portions, and said root portions being secured in grooves in the rotor extending transversely of the row.

5. In a turbine, the combination of a rotorhaving curved grooves, each groove having concentric sides, and blades havin curved root portions fitting the grooves an having abutments provided with contacting curved surfaces,-the root of each blade and one abutment surface of that blade and the contacting abutment surface of the next adjacent blade being all concentric.

6. The combination of a rotor having a row of blade-holding grooves, the grooves extending transversely of the row, and blades having root portions secured in the grooves and provided with abutting enlargements, the sides of the'root portion and grooves and one side of the enlargement of each blade being formed along arcuate surfaces having a common center disposed intermediate the axial extent of the grooves.

7. In a fluid machine, a rotor having an annular row of blade-holding grooves extending transversely of the row, and blades having root portions inserted in said grooves and abutting enlarged portlons, the sides of each groove and the root portionthere n being formed along arcs having a common center, one side of an enlarged portion being formed along an arcuate surface whose center coincides with said common center of the associated root portion and the opposite side being formed conjugate to the adjacent side of the enlarged portion abutting therewith. I

8. In a fluid machine, a rotor having an annular row of blade-holding grooves ex tending transversely of the row, and blades having root portions inserted in said grooves and abutting enlarged portions, jther'sides V of each groove and the root p'ort i'on' therein .being sformed alOng arcs having a common center; disposed intermediate the I axial, ex'-.

tent of the-grooves, one side of an. enlarged "port-ion being formed 'along an arcuate su'r facewhos'e center coincides with said commonlj. center off the associatedlroot portion and the opposite r-side'being formed conjugate to the adjacent side of the enlargedporitionf abutting therewith; I I A 9. In a fluid machine, ga' rotor having an annular row of 1 blade-holding grooves having concave and convex sides' and extending transversely of the row, I and blades having root portions formed with concave and consides inse'rted'inthe grooves and having abutting-enlarged portions, the-concave and convex sides of the grooves and root portions being formed to permit'ins'er'tion of the root portions in the grooves laterally of the row from-one side thereof,means extending laterally of the concave and convex-sides of the root' portion's for anchoringthesame in the grooves, one side of theenlarged portion of a blade and the adjacent or abutting side of the enlarged portionof the adjacent blade being formed to permit'insertion of the root portion ofthe first blade while the second bladei's'in'place, and. the other side of the enlarged portion of the first blade being formed similarly to the first-mentioned side thereof but spaced therefrom a distance equal to the pitch of the blades 'at the enlarged Portions. V r

' 10; In a fluid machine, a rotor having-an annularrow of blade-holding grooves hav-' ing concave and convex sides and extending transversely of't'he'royv, and blades havlng root portions formed with-.concaveand convex sides inserted n the grooves and having 1 enlarged portions contacting with each other -along contacting surfaces, the" concave and- "convex sides of the slots androot-portionsbeing formed to permit insertion ofthe root portions in the grooves laterally of the row from one side thereof, means extending laterally of the-concave and convex sides of the root portions for anchoring the same in the grooves, one side of the enlarged portion of a blade and the adjacent or contacting side of the enlarged portion of the adjacent blade being formed to permitinsertion of the root portion of the first blade while the second blade is in place, and the other side of the enlarged portion of the first blade being formed similarly to the first-mentioned side thereof but spaced therefrom a distance equal to the pitch of the blades at the enlargedv r I i 3%183358 the; grooves, and. abutting enlarged portions intermediate the blade; and root portions, saidi root and enlarged portions having curved; sides, one side of the enlarged por- 5 tion of a blade being-concentric with the corresponding side of the root portion of the bladeand the opposite side of the enlarged portion being conjugate to the abutting side of the adjacent enlarged portion.

12. In a fluid machine, the combination of a rotor having an annular row ofblade-holding grooves, havingncurved sides and extending transversely of the row, and blades having blade politions, root portions secured inv 5 the grooves; and abutting enlarged portions intermediate the blade and root portions, "said root and enlarged portions having curvedsides,v one side. of the enlarged portions and the corres ondingside of the root '20 portion of a blade eing formed along arcs 7 having a common center disposed intermediate the axial extent of the grooves, and the opposite side of the enlarged portion being conjugate to, the abutting side of the adjacent enlarged portion. a 13. In a fluid machine,la rotor having an X annular row of "blade-holding grooves extending transversely of the row, and blades having root portions inserted in the grooves and having abuttingenlarged portions, the

side Walls'of the groovesandthe-sides of the root portions being formed with interengaging parts retaining the root portions in the grooves but permitting insertion of the root .85 portions in the grooves laterally'of the row from one side thereof; the sides of the grooves and the root portions and the abutting surfaces of the enlarged portions being so formed and arranged relatively to each other i 40 that Whenone blade is in place, the root portion of a-next adjacent blade may be inserted andwhen inserted, the enlarged portion thereof contacts the enlarged portion of said one blade and locks the same against movement lateral-1y;v oiithe row.

In testimony whereof, I have hereunto subscribed iny name'this 27th day ofMay, 19.29.

BENJAMIN V. DEN-SMOKE.

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