US3588279A

US3588279A - Shrouded rotor blade structure

Info

Publication number: US3588279A
Application number: US857946A
Authority: US
Inventors: Ralph E Mcginnis
Original assignee: Westinghouse Electric Corp
Current assignee: CBS Corp
Priority date: 1969-09-15
Filing date: 1969-09-15
Publication date: 1971-06-28
Anticipated expiration: 1988-06-28

Abstract

A SHROULDED ROTOR BLADE STRUCTURE FOR AN ELASTIC FLUID AXIAL FLOW TURBINE OR COMPRESSOR COMPRISING AN ANNULAR SERIES OF SEGMENTS ARRANGED IN END-TO-END ABUTMENT WITH EACH OTHER. EACH SEGMENT HAS TWO TENONS OF SEMICYLINDRICAL SHAPE, WHICH HEREINAFTER WILL BE CALLED SEMITENONS, ONE ON EACH END, EXTENDING RADIALLY OUTWARD WHEREIN THE FLAT FACES OF THE SEMITENONS ABUT THEIR MATING HALVES ON THE ADJACENT SEGMENTS FORMING TWO-PIECE TENONS. RINGS TIGHTLY ENCIRCLE THE TENON STRUCTURES TO MAINTAIN THE SEMITENONS IN ABUTMENT. THE TENONS ARE DEFORMED LOCKING THE RINGS IN PLACE.

Description

United States Patent Inventor Ralph E. McGinnis Folsom, Pa.

Appl. No. 857,946

Filed Sept. 15, 1969 Patented June 28, 1971 Assignee Westinghouse Electric Corporation Pittsburgh, Pa.

SHROUDED ROTOR BLADE STRUCTURE l0 Claims,3Drawlng Fig.

U.S.Cl. 416/191, 416/195 lnt.Cl 1-0ld 5/22 FieldofSearch 416/191, 189,195,196

[56] References Cited UNITED STATES PATENTS 2,366,142 12/1944 Allen 416/191 3,070,350 12/1962 Stewart 416/191 Primary Examiner- Everette A. Powell, Jr. Attomeys-A. T. Stratton, F. P. Lyle and F. Cristiano, Jr.

ABSTRACT: A shrouded rotor blade structure for an elastic fluid axial flow turbine or compressor comprising an annular series of segments arranged in end-to-end abutment with each other. Each segment has two tenons of semicylindrical shape, which hereinafter will be called semitenons, one on each end, extending radially outward wherein the flat faces of the semitenons abut their mating halves on the adjacent segments forming two-piece tenons. Rings tightly encircle the tenon structures to maintain the semitenons in abutment. The tenons are deformed locking the rings in place.

PATENTEDJUNQB 1911 3588.279

NESSES INVENTOR RALPH E. McGlNNIS SIIIROUDED ROTOR BLADE STRUCTURE BACKGROUND TO THE INVENTION i are A. .l. Partington, US. Pat. No. 3,367,629 and P. D. Saunders, U.S. Pat. No. 3,367,630 both issued on Feb. 6, 1968 and both assigned to the same assignee as this invention.

This invention provides a novel structure employing a continuous shroud which minimizes vibrational stresses and minimizes thermal-fatigue strains in the blade structure.

SUMMARY OF THE INVENTION In accordance with this invention a turbine or compressor is provided with an annular row of rotor blades and a shroud structure surrounding the blades. The shroud consists of an annular series of segments which are on the outermost portion of the blades tips and integral therewith, arranged in end-toend abutment with each other. On the opposite ends of each segment is a semitenon extending radially outward with respect to the axis of rotation of the rotor. Each semitenon has a flat face flush with the edge portion of the segment facing the flat face of the semitenon on the adjacent segment. The semitenons are substantially identical to each other in size and shape. A two-piece tenon is formed when the flat face of a semitenon abuts its mating half on the adjacent segment. A cincture encompasses the semitenons to insure the abutting relation. The tenon is deformed, holding the cincture in compressive abutment between the tenon and the shroud segment.

Elastic fluid flows axially through the turbine at high temperature and pressure, driving the rotor structure. As the shroud expands or contracts due to the centrifugal and thermal forces, the stresses concentrate in the extruding portions of the shroud which are the tenon structures. The semitenons are flexible and deflect, relieving part of the forces transferred to the cincture and minimizing the centrifugal and thermal induced strains in the blade structure.

DESCRIPTION OF THE DRAWINGS Reference may be had to the following drawings for a better understanding of the nature and objects of the invention in which:

FIG. 1 is a view in perspective of a portion of a bladed rotor structure in accordance with the invention shown in the various stages of fabrication;

FIG. 2 is a developed view in plan of the shroud portion shown in FIG. 1; and

FIG. 3 is an enlarged sectional view of the tenon structure taken along line III-III in FIG. 2.

DESCRIPTION OF THE PREFERRED EMBODIMENT FIG. 1 shows a fragmentary view of a rotor structure 9, only part of which has been shown, it being understood that the structure is part of an elastic fluid axial flow turbine or compressor (not shown). The FIG. shows the construction of the invention from the initial to the final stages where in sequential order from the top of the FIG. there is a semitenon 18, a two-piece tenon 22 before riveting, an exploded view of a tenon structure 24, a tenon structure 24a after riveting, and a sectional view of a riveted tenon structure 240.

The rotor structure includes a portion of a rotor 10, a'transverse annular row of blades 11, which are substantially identical to each other, and a shroud structure 12 surrounding the outennost tips of the blades 11. The blades 11 are of the usual air foil contour, as well known in the art, and are attached to the rotor 10 by means of root portions 13 disposed in a suitable groove 14 in the rotor The blades 11 extend radially outward relative to the longitudinal axis of rotation of the rotor (not shown) and they may constitute one row of a multistage axial flow turbine.

The shroud 12 comprises an annular series of segments or blade covers 15, which are integral with the outermost tips of the blades 11. The segments 15 are substantially identical to each other, and, as best indicated in FIG. 2, for purposes of illustration, are of parallelogram shape in plan. The segments are in end-to-end relationship forming a continuous 360 shroud.

Each blade 11 has two

semitenons

17, 18 integral therewith which may also be integral with the segment 15. The

semitenons

17, 18 are formed in mating halves. There is one semitenon 17 on the left end of segment 15 and one semitenon 18 on the right end. The left semitenon 17 has a flat face 20 and the right semitenon 18 has a flat face 21 which are longitudinal of the blade 11. The flat faces 20, 21 of the

semitenons

17, 18 are flush with the edge portions of the segment 15 and are oriented towards the

flat faces

21, 21 of the

adjacent semitenons

18, 17. The

faces

21, 21 of the

semitenons

17, 18 abut the

faces

21, 20 of their

mating halves

18, 17 on the adjacent segments forming a two-piece tenon 22. From a view looking into either edge of the segment 15, the

semitenons

17, 18 and the edge portions of the segment 15 form an inverted T. This is best illustrated in FIG. 1 from a view looking into the leftwardmost face 20 of the semitenon 17 on segment 15. The

semitenons

17, 18 are arranged in an annular row along the center of the segments 15 and the row is curved conforming to the curvature of the shroud 12. The two-piece tenon 22 may be an irregular, nonsymmetrical solid, or a regular solid in which all angles and sides are equal, such as a polygon, or the tenon may be a solid of revolution which has circular cross section taken parallel to the axis of rotation of the rotor, such as a cylinder as shown in FIGS. 1 and 2.

Fastening means 23 may be a cincture which conforms to the shape of the tenon 22 and interacts therewith to firmly hold the abutting

semitenons

17, 18 together and to thereby secure the adjacent segments 15 in abutting end-to-end relationship. For purposes of illustration, and as best shown in the exploded view of FIG. 1, the cinctures are cylindrical rings 23. Each ring 23 fits over the cylindrical tenon 22 to securely encircle it to maintain the

semitenons

17, 18 and the segments 15 in abutting relationship.

As best illustrated in the sectional view in FIG. 1 and in FIG.

3, the tenon 22 is deformed as indicated by 220 by riveting and mushrooms over the fastening means or cincture 23 to maintain the cincture in compressive abutment between the tenon 220 the segment 15. The riveting locks the cincture 23 in place to prevent loss of the cincture in operation.

The resulting structure is a continuous 360 shroud which eliminates the resonant condition and thereby the resulting stresses and minimizes the effect of the partial admission loading stresses. Furthermore, as the structure goes through a thermal cycle, thermal strains and stresses will result due to the temperature differential between the rotor 10 and the shroud 12. The

semitenons

17, 18 will flex minimizing the thermal strains and stresses and because the cincture 23 is in abutment with the semitenons, it absorbs some of the thermal forces, further minimizing the thermal strains.

Although the tenon 22 has been shown for purposes of illustration to be a two-piece tenon, and has been defined as semitenon, the tenon need not be limited to two-pieces. Accordingly, in some of the claims, the term partial-tenon has been employed.

Since numerous changes may be made in the abovedescribed construction, and different embodiments of the invention may be made without departing from the spirit and scope thereof, it is intended that all the matter contained in the foregoing description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

lcIairn:

1. ln elastic fluid utilizing apparatus,

a rotor having a transverse annular row of blades,

a continuous shroud surrounding the radially outermost tips of the blades,

said shroud comprising an annular series of segments arranged in end-to-end abutment with each other, partial-tenons extending radially outward on opposite ends of said segments,

said partialtenons abutting the partial-tenons on the adjacent segments forming multipiece tenons,

and fastening means connecting said multipiece tenons to firmly secure the segments in abutting relationship.

2. The structure defined in claim 1 wherein the shroud segments are integral with the blades and substantially identical to each other.

3. The structure defined in claim 1 wherein the partialtenons are substantially identical mating halves.

4. The structure defined in claim 1 wherein the partialtenons are integral with the blades.

5 The structure defined in claim 1 wherein the partialtenons have flat faces'and the edge portions of the segments and the flat faces form Ts.

6. The structure defined in claim 3 wherein the partialtenons abut their mating halves on the adjacent segments to form two-piece tenons.

7. The structure defined in claim 3 wherein the partialtenons are of semicylindrical shape.

8. The structure defined in claim 1 wherein the fastening means are cinctures which encompass the tenons.

9. The structure defined in claim 8 wherein the tenons are deformed by riveting to thereby hold the cinctures in compressive abutment.

10. The structure defined in claim 1 wherein the partialtenons are substantially identical mating halves,

said partial-tenons abutting their mating halves on the adjacent segments to form two-piece tenons,

said partial-tenons being semicylindrical in shape, and

the fastening means being rings encircling the two-piece tenons.