US2985426A - Bladed rotor construction for axialflow fluid machine - Google Patents

Description

May 23, 1961 P. E. HUNTER ET AL 2,985,426

BLADED ROTOR CONSTRUCTION FOR AXIAL-FLOW FLUID MACHINE 6 Sheets-Sheet 2 Filed July 11, 1955 May 23, 1961 P. E. HUNTER ET AL 2,985,426

BLADED ROTOR CONSTRUCTION FOR AXIAL-FLOW FLUID MACHINE 6 Sheets-Sheet 4 Filed July 11, 1955 F/gJO.

May 23, 1961 P. E. HUNTER ET AL BLADED ROTOR CONSTRUCTION FOR AXIAL-FLOW FLUID MACHINE 6 Sheets-Sheet 5 Filed July 11, 1955 P. E. HUNTER ET AL BLADED ROTOR CONSTRUCTION FOR AXIAL-FLOW FLUID MACHINE May 23, 1961 6 Sheets-Sheet 6 Filed July 11, 1955 Unite Pontefract, England, assignors to R Royce Limited, Derby, England, a British company Filed July 11, 1955, Ser. No. 521,305 Claims priority, application Great Britain July 15, 1954 21 Claims. (Cl. 253-3945) This invention relates to axial-flow fluid machines such, for example, as compressors or turbines of gas-turbine engines, and, more specifically, the invention is concerned with bladed rotors of the type for use in such machines wherein blades are carried on a disc having a central hub portion and a rim portion, and wherein the blades have each a root comprising a blade platform, a shouldered attachment portion to engage a channel provided in the rim, and a circumferentially-narrow stem joining the platform to the attachment portion. Such a rotor will be referred to as a bladed rotor of the .type described.

This invention has for an object to provide a rotor construction in which at least some of the axially-extending passages between the circumferentially-narrow stems of the blades are sealed.

According to the present invention in one aspect, a bladed rotor of the type described has a member of fully circular ring form mounted and retained on the rim of the disc and of such radial dimension as to lie against the disc rim and extend outwards to the blade platforms thereby to blank ofi some at least of the spaces between the stems.

According to the present invention in another aspect, a bladed rotor of the type described has at both the upstream and downstream sides of the disc rim a member of fully circular ring form mounted and retained on the rim of the disc and of such radial dimension as to lie against the disc rim and extend outwards to the blade platforms thereby to blank off some at least of the spaces between the stems.

According to a feature of the invention the ring-form member or each ring-form member may be provided with radially-outwardly-extending, circumferentiallyspaced dogs, and the disc rim may be provided with a ring of complementary inwardly-directed dogs to permit the passage axially therebetween of the dogs on the ringform member to enable the two sets of dogs to be brought axially into line, thereby to retain the ring-form member axially in position on the disc rim.

In one arrangement according to this feature of the invention, the dogs are provided on a flange at the radially-inner edge of the ring-form member, the flange having an axial extent substantially equal to that of the dogs on the disc rim.

In another arrangement according to this feature of the invention, the ring-form member has one set of dogs as just set forth and also has a second set of circumferentially-spaced dogs around its outer edge and the blade platforms of alternate blades are provided with radially-inwardly-extending dogs to co-operate with the second set of dogs on the ring-form member.

According to another feature of this invention, the bladed rotor may comprise also means to retain the ringform member or ring-form members against angular displacement relative to the disc rim, or to retain the blades axially in position, or both. This means may be of any ICC 2 convenient form, for instance the means may comprise bolts, studs, rivets or the like passing through the ringform member and engaging the disc rim, or the means opposite ends of the blade roots and the disc rim,

or extend through holes in the second ring-form memher, when provided, and engage the external surface of said second ring-form member. In constructions where the dogs of the ring-form member are carried on an axial flange, the means may comprise a channel-section key engaged on said flange between a pair of dogs thereon and extending circumferentially between a pair of the co-operating dogs on the disc rim, and a locking piece located between the key and the disc to prevent disengagement' of the key from the axial flange and may comprise means to locate it circumferentially with respect to the key.

According to yet a further feature of this invention it may also be arranged that the ring-form member carries the rotating member of a seal which may be of the labyrinth kind.

Some constructions of bladed rotor of this invention will now be described with reference to the accompany.- ing drawings in which- Figure l is an axial section of the radially outer portion of one rotor construction,

Figure 2 is a view in the direction of arrow 2 on Figure 1, parts being broken away to show details of construction,

Figure 3 is a view in the direction of arrow 3' on Figure 1,

Figures 4 and 5 are views to a larger scale of parts of Figure 1,

Figure '6 is a section on the line 6-6 of Figure 5,

Figure 7 is a section on the line 77 of Figure 1,

Figure 8 is a section on the line 88 of Figure 7,

Figure 9 is a detail view taken in the direction of arrow 9 on Figure 8,

Figure 10 is a view corresponding to Figure l of a second rotor construction, I

Figure 11 is a view in the direction of arrow 11 on Figure 10, p

Figure 12 is an axial section through the radially oute part of a third rotor construction, l

Figure 13 is a view in'the direction of arrow 13 on Figure 12, and

Figure 14 is a view in the direction of arrow Figure 12.

Referring first to Figures 1 to 9, the rotor comprises a disc having a hub (not shown), an axially-thickened rim 20, and an interconnecting web portion 21, and a plurality of blades 22 mounted in the rim 20.

Each blade 22 has an integral root comprising a blade platform 23 which together with the other blade. platforms forms part of a wall of the working fluid annulus of the fluid machine, a shouldered attachment portion or root 24 which engages in a correspondingly-shaped, gerierally axial channel 26 cut in the rim 20, and a circumferentially-narrow stem 25 joining the blade platform 23 and attachment portion 24. The stems 25 of the blade roots define between them generally axially extending channels 27 and these channels convey cooling fluid to the blade roots.

aeeenae The rotor also comprises a pair of 'flat, annular rings 28, 29, whereof the ring 28 is mounted to lie against the upstream surfaces of the rim Ziluand the blade roots to seal off theupstrea'm'ends of the channels 27 and whereof the ring 29 lies against the downstream surfaces of the rim and blade roots to seal 01f the downstream ends of thechanenls 27.

The ring 28 is retained inposition by providing around its outer edge a number of equiangularly-spaced, radiallyp'rojecting dogs 30 (Figures 1, 2 and 4) and by providing at its inner edge an axial flange 33 having at its free edge radially-outwardly extending dogs 34. The dogs 30 engage in undercut channels 31 in axial projections 32 on the upstream edges of alternate blade platforms 23, and the dogs 34 engage behind radially-inwardly projecting lugs 35011 a radial flange 36 on the rim 20. The Spacing and relative angular positions of the dogs 30 and 34 and of the lugs and projections 32 are such that ring 28 can be presented to the rotor disc with the dogs 30, 34 between the projections 32 and lugs 35 respectively and can then be rotated to bring the dogs 30 into the channels31 and to carry the dogs 34 behind the lugs 35. V In this way the ring 28 is located axially with respect to the disc rim 20 and closes off one end of each channel 27.

The ring 28 is locked circumferentially by a number of equally spaced setscrews 37 (Figure .2) passing through it into the rim 2G.

The ring 28 also serves to prevent axial disengagement of the blades from the disc rim 20 in the upstream direction.

The ring 29 is similarly attached to the rotor disc to close oif the downstream ends of the channels. Thus the disc has outer dogs 38eengaging undercut channels 39 in axial projections .40 from the downstream edges'of alternate blade platforms 23, and angularly spaced inner dogs -41 on an axial flange 42 at itsinner edge engaging behind angularly spaced lugs 43 on a flange 44 on the rim 20 (Figures 1, 3 and 5). The ring 29 also serves to prevent axial. disengagement of the blades from the rim 20 in the downstream direction.

The ring 29 is :held against circumferential displacement by a number (say six) of equally-spaced locking pieces 45 which are accommodated in some of the channels 26 between the bottom of the channel 26 and the radially-inner end of the attachment portion or root 24 engaged in the channel (Figures 1,14, ;5 and.6). Each locking piece 45 has an upturned head 46 at its end adjacent the ring 28 and this head is accommodated in a cutaway 47 in the associated attachment portion 24 (see especially Figure 4). Each locking piece 45 has at its opposite end a tang 48 (Figure 5) whichprojects through ahole 49 in the ring 29 and in assembly is bent upwardly to lie against the outer surface of the ring 29.

In assembly the blades are first mounted in the rim of the disc, the ring 29 is next fitted in position and the locating tangs 48 of the locking pieces 45 bent up to the position shown and finally the ring 28 is placed in position and locked by means of the setscrews 37.

Where the blades 22 are provided with internal cooling passages so arranged thatthe inlets to the cooling pas- ;sages open to alternate channels 27 and the outlets from the cooling passages open to the remaining channels 27, the following cooling fluid supply arrangement may be .employed.

Aperipheral channel 50 (Figures 1, 7 and 8) is cut around the rim portion of the rotor disc toextend from radially inwards of the channels 26 to the apices of the projections 26 formed on the rim 20 by the channels 26, and a series of inlet bores 51 to the channel are provided from the upstream surfaces of the disc to the radially-inner end of the channel 50. A series of filler pieces 52 are provided in the channel 50 to close off communication between the channel 50 and alternate channels 27. The filler pieces 52 are of the same shape as the projections 26 between the channe s 26 and are P vided WithhOOkGd heads 53 to prevent mem dropping to the bottom of the channel 50. When the blades are in position on the rim the filler pieces 52 are retained circumferentially in position by the blade attachment portions 24. It will be seen that cooling fluid supplied to the channel 50 can fiow radially upwardsbetween the root attachment portions of pairs of adjacent blades as indicated by the arrows 57 so as to enter the channel 27 between that pair of blades but the cooling fluid cannot flow into the channels 27 next on either side of the channel formed by the pair of blades, since the filler pieces 52 block its outward flow.

After flowing through the blades the cooling fluid enters the appropriate channels 27, that is those to which entrance is blocked by the fillerpieces 52, and flows out from these channels 27 through ports formed by holes 54 (Figure 3) formed in the ring 29 to communicate with these channels.

The provision of dog or castellations on the radiallyouter edge of the plate co-operating with radially-inwardly-extending dogs or castellations on alternate blade platforms presents a further advantage in that, when, as in the present arrangement and dueto the method of blade cooling employed two different types ofblades alternate around the rotor disc the platforms of one type of blade will be carrying the inwardly-facing dogs or castellations and assembly of the blades in the incorrect order on the disc will be prevented. 'If two blades with platforms carrying radially-inwardly-facing dogs or castellations are assembled in adjacent positions it will be impossible to present the dogs or castellations on the locking ring axially between those on the blade platforms prior to rotating the ring to lock it axially. On the other hand two blades of the type whose platforms do not carry dogs or castellations assemble in adjacent positions will mean that all the dogs or castellations on the locking ring are not engaged with complementary dogs or castellations on the blades and the error in assembly will be apparent.

If desired, the rings 28, 29 may have formed in one piece with them the rotating memberof a labyrinth seal. For instance, as shown in Figure 1, the ring 28 which lies against the upstream face of the disc rim 20, is provided with an axial flange 55 the external surface of which is provided with a number of axially-spaced, radially-tapering circumferential fins 56 which co-operate with' stationary structure in which the rotor disc is mounted to form a labyrinth seal. Each of the fins 56 may, for instance, co-operate with a thickened lip onthe inner surface of a frusto-conical member carried onstationary structure coaxially with the rotor disc, the frusto-conical members being axially spaced and nested. This seal is of a form described and claimed in British Patent No. 663,386 (Rolls-Royce Limited).

Referring now to Figures IO-and 1 1,.there is shown a second rotor construction comprising a rotor disc having a central hub-60, a rim 61 and an interconnecting web 63. The rotor also comprises a number of blades 62 each having a root comprising a platform portion 64, a shouldered attachment portion 65 to' engage in a correspondingly-shaped channel 65 extending generally axially across the disc rim 61, and a circumferentially-narrow stem 66 interconnecting the blade platform 64 and the attachment portion 65.

The channels 67 formed between the stems 66 of the blade roots are closed off by a pair of rings 68, 62, of which ring 68 lies against the upstream surfaces of the rim 61 and blade roots to close oif the upstream ends of the channels 67 and of which the ring 69 lies against the fpieces 70 extend across the disc rim 61 in the channels 65 for the attachment portions 65 of the blades between their radially inner ends and the bottoms of the channels 65 and also extend through holes 68 and 69 formed in the rings 68 and 69. The heads 71 of the locking pieces lie against the external surface of one of the rings 68, 69 and the tangs 72 are bent up to lie against the outer surface of the other ring.

If desired, the rings 68, 69 may have welded to them 'tabs 73 which project radially inward into notches 74 in axial flanges 74 on the disc rim 61. The flanges 74 also serve to position the rings 68 and 69 coaxially on the rotor disc.

Referring now to Figures 12 to 14, there is shown a 'rotor construction in which sealing rings 80 and 81 are retained against the upstream and downstream surfaces respectively of the disc rim 82 and blade roots 83 solely by means at their inner edges.

The disc rim 82 has circumferentially-spaced radiallyf'inwardly-projecting lugs 84 adjacent the inner edges thereof and the rings 80, 81 have at their radially inner edges :axial flanges 85 provided with circumferentially spaced radially-outwardly-projecting dogs 86 to engage behind the lugs 84 with a clearance from the adjacent surfaces 87a of the disc web 87. As with the construction on Figures 1 to 9, the rings 80, 81 are mounted in position by entering dogs 86 between the lugs 84 and then rotating the rings to bring the dogs 86 behind the lugs 84.

Circumferential locking of the rings is achieved in this construction by providing a series of keys 88 to retain the rings against rotation with respect to the disc and corresponding locking pieces 89 to retain the keys in position.

Each key 88 extends angularly between a pair of lugs 84 (Figures 13 and 14) and is of channel section with the channel 88a facing the adjacent ring 80 or 81. When the key 88 is in position, the adjacent portion of the flange 85 engages in the channel 88a between the limbs 88b of the key so positioning the key radially, and this portion of the flange is cut back as indicated at 85a. The base 880 of the key lies circumferentially between the two adjacent dogs 86 and so when the key is in position rtation of the ring 88 relative to the rim 82 of the disc is prevented.

Bach locking piece 89 is of such shape as to occupy the space between the associated key 88 and the surface 87a of the rotor disc, and thus disengagement of the key 88 from flange 85 is prevented. The locking piece 89 has a portion 89a which fits within the channel formed between the disc 87 and a flange 90 having the lugs 84 at its radially-inner edge and this portion 89a of the locking piece 89 bears on the radially outer surface of the key 88. In this way, the locking piece is trapped radially.

The locking piece 89 extends radially inwards beyond the flange 85 and has at the circumferentially-spaced ends of its radially inner portion deformable tangs 91, which when the locking piece 89 is in position embrace the key 88 (see especially Figure 14) so preventing circumferential displacement of the locking piece.

The number of keys and locking pieces employed will usually be considerably less than the number of lugs 84 and they may be distributed equi-angularly around the disc, or in a manner to ensure a selected angular position of the ring 88 or 81 with respect to the disc rim 82.

In assembly, theb lades are positioned on the disc rim and then the rings 80, 81 are rotated and attached in position with the dogs 86 behind the lugs 84. The locking pieces 89 and keys are then assembled, one tang 91 of each locking piece being initially bent to its final position; the locking piece 89 first positioned behind a dog 84, the associated key 88 inserted in engagement with the flange 85, the locking piece 89 is displaced circumferentially to behind the associated key 88 with the bent tang 91 against one end of the key, and finally the second tang 91 is bent to lie against the other end of the key.

In further constructions one sealing ring only is provided in the rotor construction and this ring bears on one surface of the disc rim and the adjacent surfaces of the, blade roots to seal 011 one end of each channel between the blade root stems. The ring may beheld in position as described above with reference to Figures 1 to 14, and where locking pieces such as are shown in the construc-' tions of Figures 1 to 9 and 10 to 11 are employed, these locking pieces may be arranged at their ends remote from the ring to co-operate with both the adjacent surfaces of the disc rim and blade roots to retain the blades in posi tion against axial displacement away from the ring. In. this case of course a locking piece will be provided in the bottom of each of the blade root channels.

In other arrangements the sealing rings may be retained axially in position by means of bolts, studs, rivets or the like passing through the ring and engaging the disc n'm.

We claim:

1. A bladed rotor for an axial-flow fluid machine comprising a disc having a central hub portion and a rim portion; a ring of blades, each blade having a root portion including a blade platform, the blade platforms together forming a substantially continuous annular Wall, a shouldered attachment root portion engaging a correspondingly-shouldered channel .in the rim portion of the disc and a radially-extending stem portion joining the blade platform to the shouldered attachment portion, the stem portion being circumferentially narrower than the blade plat-form whereby axially-extending channels are afforded between adjacent stem portions; a member of annular ring form which is separate from the disc and blades, said rim portion of the disc having an axially-facing surface upon which said member of annular ring form is mounted in position, is concentric with the disc, has a radial dimension'to extend from the rim portion to the blade platforms, and lies in contact against the disc rim and against all of the stem portions of the blades thereby to blank off the adjacent ends of some at least of said axiallyrextending channels; and retaining means operatively engaging the rim portion of the disc and the ring-form member and detachably retaining the ring-form member axially and angularly in position against the rim portion and the stem portions. I I

2. A bladed rotor as claimed in claim 1, wherein said retaining means comprises radially-outwardly-ex tending, circumferentially spaced dogs on the ring-form member and a ring of complementary inwardly-directed lugs on the rim portion, said inwardly directed lugs having a circumferential spacing permitting the ring form member to be mounted on the rim portion by the passage of the dogs on the ring-form member axially between the lugs on the rim portion and thereafter by rotating the ring-form member angularly to bring the dogs on the ring-form members and the lugs on the rim portion axially into line, thereby to retain the ring-form member axially in position on the disc rim, and locking means co-operating with the ring-form member and the rim portion and locating the ring-form'member angularly with respect to the rim portion. 5

3. A bladed rotor as claimed in claim 2, wherein the radially-outwardly-extending dogs are provided on an axial flange at the radially-inner edge of the ring-form member at a position axially spaced from the portion of the ring-form member which engages the rim portion, by a distance substantially equal to the axialdimension of the lugs on the rim portion.

4. A bladed rotor as claimed in claim 3, wherein the ring-form member has a second set of circumferentiallyspaced dogs around its radially outer edge and the blade platforms of alternate blades are provided with radiallyinwardly-extending dogs co-operating with the second set of dogs on the ring-form member.

5. A bladed rotor as claimed in claim 3, wherein said axial flange has a portion of reduced axial dimension between a pair of the dogs thereon, and said retainer members are a channel-section key and a locking piece,

the her hav n dimen o e ise of its chann equal to the circumferential spacing of said pair of the do 94 t e .axial efian e a e n positioned twee said pair of the dogswith the reduced axial dimension portion of the axial flange entered into the channel in the. key, and said locking piece being located between and axially abutting the'key and'the disc to prevent disengagement of the key from the reduced dimension portion of the axial flange, said locking piece having portions engaging the key to locate the locking piece circumferentially with respect to the key.

6. A bladed rotor as claimed in claim 5, wherein said portions of the locking piece to locate the locking piece with respectatothe key are a pair of tangs at the circumferentially-spaced ends of the locking piece bent into contact with the circumferentially-spaced ends of th ey- 7. A bladed rotor as claimed in claim 1, wherein the ring-form member carries the rotating member of a seal. 8. A bladed rotor as claimed in claim 7, wherein said rotating seal member comprises an axial flange on the ring-form member extending in a direction away from the disc, which flange is provided with a series of axiallyspaced circumferential ribs adapted to co-operate with stationary structure to form a labyrinth type seal. 9. A bladed rotor according to claim 1 comprising also means for supplying cooling fluid to the axiallyextendingchannels between the stems of the blade roots to. cool the blades, wherein the ring-form member is provided with cooling-fluid transfer ports communicating with some of the axially-extending channels, the

10. A bladed rotor according to claim 1, wherein said a retaining means comprises locking pieces extending through the ring-form member and the disc, each locking .piece axially abutting the external surface of the ring form member by one end and engaging the disc by its opposite end.

'11. A bladed rotor as claimed in claim 1, wherein said retaining means comprises circumferentially-spaced tabs on the ring-form member, an axial flange on the disc having circumferentially-spaced notches therein, the tabs engaging the notches.

12. A bladed rotor as claimed in claim ll, wherein said axial flange also serves to locate the ring-form member coaxially with the disc.

13. A bladed rotor according to claim 11, wherein said retaining means also comprises locking pieces extending through the ring-form member and the disc, each locking piece axially abutting the external surface of the ring-form member by one end and engaging the disc by its opposite end.

14. A bladed'rotor as claimed in claim 1, wherein said retaining means comprises locking pieces accommodated in the blade root channels radially inwards of the blade roots which locking pieces have portions at .one end which extend through holes in the ring-form member and engage its external surface and have portions at the. opposite end which bear against the opposite ends of the blade roots.

15. A bladed rotor as claimed in claim 1, wherein said retaining means comprises locking pieces accommodated in the blade root channels radially inwards of the blade .roots which locking pieces have portions at one end which extend through holes in the ring-form member and engage its external surface and have portions at the opposite end which bear against the opposite ends of the blade roots and the disc rim portion.

16. A bladed rotor for an axial-flow fluid machine Omprising a disc having a central hub portion and a rim portion; a ring of blades, each blade having a root portion including a blade platform, the blade platforms together ,forming a substantially continuous annular wall, a shouldered attachment portion engaging a correspondingly-shouldered channel in the rim portion of the disc and a radially-extending stem portion joining the blade platform to the shouldered attachment portion, the stem portion being circumferentially narrower than the blade platform wherebyaxially-extending channels are afforded between adjacent stem portions; members of annular ring form adjacent both ends of said channels, each of which members is separate from the disc and blades, said rim portion of the disc having an axially-facing surface upon which said members of annular ring form are mounted in position, is concentric with the disc, has a radial dimension to extend from the rim portion to the blade platforms, and lies in contact against the disc rim and against all of .the stem portions of the blades thereby to blank off the adjacent ends of some at least of said axially-extending channels; and retaining means operatively engaging the rim portion of the disc and the ring-form members and detachably retaining the ringform members axially and angularly in position against the rim portion and the stem portions.

17. A bladed motor as claimed in claim .16, wherein said retaining means comprises locking pieces extending through the rim portion of the disc and projecting at its ends through apertures in the ring-form members, each locking piece having at each end a part bearing against the external surface of the adjacent ring-form member. 18. A bladed rotor according to claim 17, wherein said retaining means comprises also circumferentiallyspaced tabs on the ring-form members, axial flanges projecting fromeach of the axially-spaced sides of the disc rim, said axial flanges having circumferentially-spacedv notches therein, and the tabs engaging in the notches.

19. A bladed rotor as claimed in claim 16, wherein said retaining means comprises for each ring-form member radially outwardly extending, circumferentiallyspaced dogs on the ring-form member and a ring of complementary inwardly-directed lugs on therim portion of the disc said inwardly-directed lugs having a circumferential spacing permitting the ring-form member to be mounted on the'rim portion by'the passage of the dogs on the ring-form member axially between the lugs on the rim portion and thereafter by rotating the ring-form member angularly to bring the dogs on the ring-form member and the lugs on the rim portion axially into line, thereby to retain the ring-form member axially in position on the disc rim, and locking means co-operating with the ring-form'member and the rim portion and locating the ring-form member angularly with respect to the rim portion.

20. A bladed rotor as claimed in claim 19, wherein each of the ring-form members has at its radially-inner edge an axial flange whereon the associated radiallyoutwardly-extending dogs are provided, the dogs being axially spaced from the portion of the ring-form memher which engages the rim portion, by a distance substantially equal to the axial dimension of the lugs on the rim portion.

21. A bladed rotor according to claim20, wherein .each ring-form member has a second set of circumferentially-spaced dogs around its radially-outer edge and the blade platforms of alternate blades are providedwith radially-inwardly-extending dogs co-operating with the second set of dogs on the ring-form member.

References Cited in the file of this patent FOREIGN PATENTS

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