US2640679A - Turbine or compressor stator ring - Google Patents

Description

June 2, 1953" J. B. wHEATLEY ET AL 2,640,579

TURBINE OR `COMPRESSOR STATOR RING Filed March-.21, 1950' 2 Sheets-Sheet l June 2, 1953 J. B. wHEATLEY ETAL TURBINE OR lCMPRESSOR STATOR RING 2 Sheets-Sheet `2 Filed March 21, 1950 Patented June 2, 1953 UNITED STATES PATENT OFFICE TURBINE OR COMPRESSOR STATOR RING John B. Wheatley, Arthur W. Gaubatz, and

Charles C. Anderson, Indianapolis, Ind., assignors to General Motors Corporation, Detroit, Mich., a corporation of Delaware Application March 21, 1950, Serial No. 150,954

4 Claims. l

This invention relates to multistage rotary machines and particularly to an improved stator ring and seal structure for axial flow elastic fluid compressors or turbines.

The: present invention is shown as being embodied in the stator ring structure of the compressor of such a turbine and comprises an outer ring or band which radially spaces the stator blades, an inner sealing means of one or more annular channels, and stator blades positioned between and secured to the outer band and the inner sealing channels. The bases of the outer band and the sealing channels are apertured to receive projections or tenons formed on the ends of the stator blades, which blades are secured to the outer band and sealing channels by heading the blade tenons. This outer band is seated in an annular slot or groove formed in the inner surface of the compressor casing.

The principal object of the invention is to provide a stator ring structure which is simple and inexpensive to manufacture and assemble, light in weight, and which possesses adequate structural strength. These features, incorporated into the present invention, are particularly desirable in aircraft turbine construction, where weight is such a. major consideration. The outer band and the sealing channels are preferably constructed wholly of rolled stock, resulting in a ring structure which possesses little weight and sufcient rigidity. Moreover, the entire ring structure may be constructed in two semi-circular segments which are secured, one at a time, to the turbine compressor casing, thereby facilitating assembly of the ring.

Another object of the invention is to provide an improved construction and arrangement whereby loss due to leakage of elastic fluid around the blade tips is reduced to a minimum. This is accomplished in accordance with the invention by the aforementioned sealing means comprising one or more annular channels having apertured bases to which the stator blade tenons are afxed. The channel anges are adapted to project into proximity with portions of the rotor discs, thereby constituting a very eiective labyrinthine seal as Well as a structural support and spacing device for the stator blades.

Other objects and advantages of the invention will more fully appear from the following description taken inv conjunction with the accompanying drawings in which:

Figure l is a fragmentary longitudinal section of a compressor of an axial flow elastic fluid tur- 2 bine provided with blades and a stator ring structure embodying the invention.

Figure 2 isk an enlarged sectional view, partly broken away, taken along the line 3-3 of Figure 2, showing one of the stator blades with the outer band and Sealing channels -attached thereto.

Figure 3is an end view, taken along theline 3-3 of Figure 2, showing the semi-circular construction of the stator ring structure.

Figure 4 is an enlarged fragmentary view, partly in elevation and partly in section, of aportion of the stator ring structure, showing the method of attachment of the blades to the outer band and the sealing channels.

Referring to the drawings, the compressor of an axial iio-w elastic fluid turbine having a casing Ill is shown in Figure 1. Within the casing IIJ is a` rotor with a shaft l2 passing through rotor discs I4 and IE containing rotor bladesy I8 and 20, respectively. A stator ring structure is located o-n either side of each row of rotor blades, each stator ring comprising a row of stator blades 22 secured between a circular outer band 24 and annular sealing channels 26 and 28. During operation the elastic uid is directed by the noz- Zles formed by the stator blades to the passages defined between the adjacent rotor blades and discharged from the latter to the nozzles formed by the next annular series of stator blades.

Leakage of fluid around the stator blades is materially reduced by the provision of the aforementioned sealing means secured to the inner tips of the stator blades. This sealing means, in a preferred embodiment, as sho-wn in the drawings, comprises the two concentrically arranged annular channel members 26 and 28. The larger outer channel 26 has a base or shroud portion 30 which may project beyond the edge of the stator blades 22, as shown in Figures 1 and 2, and two inwardly directed sealing flanges 32 and 34. The smaller inner channel, also comprises a base portion 36 and two inwardly extending sealing flanges 38 and 40, the base 36 of this smaller channel havinga width less than the base portion 3U of the larger outer channel 26 and seated thereupon. The edges of the resultant series of axially spaced flanges 32, 34, 38 and 40 are adapted to project into proximity with an axial extension 42 of rotor disc I6, thereby-acting as a very effective labyrinthine seal. The embodiment of the invention shown in the drawings is one where the sealing channels are adapted to cooperate with a conical projection of the rotor disc. These flanges can be of various lengths or shapes adapt- 3 ed to t irregularly contoured or rounded sealing members or surfaces on the rotor. The exact construction of the sealing flanges will be governed, of course, by the contour of such rotor members.

As shown in the drawings, the tip portions of the compressor stator blades 22 are shaped to provide outer and inner projections or tenons 44 and 46, respectively. The details of construction of these blade tenons and the method of attachment of the sealing channels 26 and 28 and the outer band 24, which will be subsequently described, are best sho-Wn in Figures 2 and 4. It can be seen that the larger annular sealing channel 2E is preferably of greater thickness than the smaller inner sealing channel 28, the former supplying most of the rigidity to the seal structure. The smaller channel is principally a sealing device, although it too contributes to the structural strength o-f the stator ring and aids in the alignment of the stator blades. The inner tenon 4B of the stator blade 22 has a length slightly greater than the combined thicknesses of the bases and 36 of the sealing channels v26 and 28 to permit the heading of the tenons by electric upsetting or other suitable means, thereby securing the sealing channels to the blades. Similarly the length of the outer blade tenon 44 is sufliciently greater than the thickness of the outer band 24 `to allow the ready attachment of the blades to the outer band by heading the blade tenons.

The base v3i) of the larger outer sealing channel 26 and the base 36 of the smaller inner sealing channel 28 are provided throughout their circumferences with apertures 48 and 50, respectively, which are aligned to permit the inner tenons 4S of the stator blades 22 to be positioned in these apertures of both sealing channels, the same blade tensions being used to secure both these members to the blade tips. As previously stated. the blade tenons 48 are upset by appropriate means, the resultant tenen heads 52 being best shown Figure 4. Thus both sealing channels 26 and 2e are securely fastened tothe same blade tenons in a single operation without the necessity for any additional connecting means.

The outer band 24 extends laround the inside of and :engages the casing. This band, which functions principally to secure and radially space the stator blades, has `a base 54 provided with 'apertures 56 throughout .its circumference, with the outer tenons -44 of the stator blades positioned in these Aapertures and headed, as hereinbefor'e described, to secure the .blades to the vother band. As shown in the drawings, the outer :band 2d may be formed with outwardly projecting peripheral flanges or rims 58 and 5U, which are vseated in an annular slot or groove 52 formed in the inner surface Aof the casing. 'These rims '58 and 6B, engaging the fcasing `groove $2, prevent vaxialmovement of the ring structure and Aaid in the blade alignment, as well as increase the structural strength of the stator ring. Moreover, as can be seen in Figures ,1 and 2, -th-is arrangement :provides an annular clearance space between the base 54 of the outer stator band `24 and the casing lil .for the formed blade tenon heads 64.

The vouter band 24 and the sealing channels 26 vand 28 are each preferably constructed of rolled lstock and formed in two semi-circular segments, as shown 'in vFigure 13, to facilitate assembly of the stator ring. These ring members.

are sufficiently flexible so that after the inner blade tenons 46 are positioned within the apertures 48 and 5G in the sealing channels 26 and 28, and before any of the tenons are headed, these channels may be straightened out enough to permit the insertion of the outer blade tenons 44 into the apertures 56 of the outer band 24, which in turn may be ysprung over the outer tenons. Adequate clearances may be provided between the apertures 48, 5G and 56 and the blade tenons 44 and 46 to expedite this procedure. Keepers 5S, shown in Figure l, may be employed to retain the ring structure within the'casing during assembly.

It will be understood that the term compressor, as -used hereinbefore, is not intended as a limitation on the use of the invention and vthat the described stator ring structure is adapted generally for use in compressors, turbines and similar rotary machines where it is necessaryto have a stationary blade assembly adjacent to rotor blades to direct the iiow of elastic fluid.

We claim:

l. A blade assembly for a iiuid machine of the dynamic type comprising, in combination, an arcuate outer strip, at least one arcuate inner strip of channel vform with the flanges directed inwardly, and a plurality of blades extending from the outer strip to the inner strip, the depth of the said arcuate strips in a radial direction being small relative to the length of the blades from one strip to the other, the said strips when unassembled being light and flimsy Aand readily deflected in a radial ldirection relative to the arcs thereof, means yon each end of each .blade abutting -on each of said strips throughout sub substantially the axial extent of said blades, the blades extending radially with respect to the arcs of the strips from a common center and being rigidly secured to the said strips so that the strips and blades cooperate .to form a rigid lattice and stiffen the said strips.

2. A blade assembly as claimed in claim 1 in which the arcuate extent of the strips is substantially degrees.

`3. A blade assembly as claimed in claim 1 in which the blades have tenons at each end and theV abutment .means includes shoulders at the bases of the tenons, openings through the strips through which the tenons extend, the blade shoulders bearing against one face of the strips, and the tenons .rigidly secured against the other face of the strips.

4,-A stator assembly for a .fluid machine of the dynamic type, comprising, in combination, a .casing formed with a shallow circumferential groove in the inner surface thereof andan arcuate blade assembly mounted therein comprising an arcuate outer strip, at least one arcuate .inner str-ip of vchannel form with the flanges directed inwardly, and a plurality of blades extending from the outer strip to the inner strip, the depth of the said arcuate strips in a radial direction being small relative to the length of the blades from one strip to the other, the said strips when unassembled being light and iiimsy and 'readily deflected in a radial direction relative to the arcs thereof, means on each end of each blade abutting one each of said strips throughout substantiall-y the axial extent jof said blades, the blades extending radially with 'respect to the arcs of the strips from a common center and .being rigidly secured to the said vstrips so that the strips 'and vblades cooperate to form a rigid lattice and stiffen thesaid strips; the said outer arcuate strip being disposed in the said groove with the inner surface of the strip substantially corresponding to the inner surface of the casing.

Number JOI-IN B. WHEATLEY. 15,154, ARTHUR W. GAUBATZ. 5 26,333 CHARLES C. ANDERSON. 24,657 371,118

References Cited in the le of this patent UNITED STATES PATENTS Name Date lo Dahlstrand May 30, 1944 Number FOREIGN PATENTS Country Date Great Britain June 27, 1907 Great Britain May 5, 1910 Great Britain Jan. 23, 1913 France Jan. 12, 1907

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