Patents
Search within the title, abstract, claims, or full patent document: You can restrict your search to a specific field using field names.
Use TI= to search in the title, AB= for the abstract, CL= for the claims, or TAC= for all three. For example, TI=(safety belt).
Search by Cooperative Patent Classifications (CPCs): These are commonly used to represent ideas in place of keywords, and can also be entered in a search term box. If you're searching forseat belts, you could also search for B60R22/00 to retrieve documents that mention safety belts or body harnesses. CPC=B60R22 will match documents with exactly this CPC, CPC=B60R22/low matches documents with this CPC or a child classification of this CPC.
Learn MoreKeywords and boolean syntax (USPTO or EPO format): seat belt searches these two words, or their plurals and close synonyms. "seat belt" searches this exact phrase, in order. -seat -belt searches for documents not containing either word.
For searches using boolean logic, the default operator is AND with left associativity. Note: this means safety OR seat belt is searched as (safety OR seat) AND belt. Each word automatically includes plurals and close synonyms. Adjacent words that are implicitly ANDed together, such as (safety belt), are treated as a phrase when generating synonyms.
Learn MoreChemistry searches match terms (trade names, IUPAC names, etc. extracted from the entire document, and processed from .MOL files.)
Substructure (use SSS=) and similarity (use ~) searches are limited to one per search at the top-level AND condition. Exact searches can be used multiple times throughout the search query.
Searching by SMILES or InChi key requires no special syntax. To search by SMARTS, use SMARTS=.
To search for multiple molecules, select "Batch" in the "Type" menu. Enter multiple molecules separated by whitespace or by comma.
Learn MoreSearch specific patents by importing a CSV or list of patent publication or application numbers.
A rotor having an annulus filler
EP2503102A2
European Patent Office
- Other languages
German French - Inventor
Paul Mason - Current Assignee
- Rolls Royce PLC
Description
translated from
-
[0001] This invention relates to a rotor comprising a rotor disc, an array of blades received in blade slots provided in the disc, and annulus fillers disposed between adjacent blades. The invention is particularly, although not exclusively, concerned with a rotor in the form of a fan of a turbofan gas turbine engine. -
[0002] The fan of such an engine typically comprises a rotor disc which has an array of slots at its periphery, which receive individual fan blades. The regions of the disc between the slots constitute posts. It is common for annulus fillers to be provided between adjacent blades of the fan in order to provide an airwashed surface which has the desired aerodynamic profile, and provides a transition between forward and aft components such as a spinner fairing and a fan rear seal. -
[0003] It is known to mount annulus fillers by securing them at their forward and aft ends to the surrounding structure. Annulus fillers are subjected to substantial centrifugal forces as the rotor rotates, and, if they are unsupported between their ends, these centrifugal forces can cause deformation. It is therefore necessary to design the annulus fillers so that they deform under rotation to provide the desired aerodynamic profile. Furthermore, the stresses imposed on the annulus filler during an operating cycle need to be analysed to ensure that the fatigue life of the component lies within acceptable limits. -
[0004] The effects of centrifugal forces on the annulus fillers can be mitigated by constructing each annulus filler in the form of a structural beam, for example an I-section beam, so that it is resistant to bending. This increases the bulk, and consequently the weight, of the component. An alternative measure is to provide connections, for example in the form of hooks, between the ends of the annulus filler, which engage cooperating formations on the periphery of the rotor disc. It is possible for annulus fillers with such hook connections to be fitted incorrectly, so that they may become detached in operation. Also, the hook connections can be susceptible to Low Cycle Fatigue cracking which, again, can result in release of the annulus filler. A further disadvantage arises from the need for corresponding profiles on the rotor disc, which increase the diameter and weight of the rotor disc and the forging from which it is machined, and also increase the amount of machining required to form the finished disc. The additional diameter means that the effective depth of the blade-retaining slots is increased, which reduces the stability of the cutting tools required to form the slots. The provision of hook features on the rotor disc thus increases the cost of the rotor discs. -
[0005] It is known fromUS 6832896 to provide a blade platform, performing the function of an annulus filler, which is made from sheet metal and is profiled to fit around the roots of the adjacent blades. The annulus filler ofUS 6832896 has side walls which lie in contact with the blades in the region of the blade roots, and this can undesirably alter the vibration characteristics of the blades, leading to early fatigue failure. Until the blades are fitted, the blade platforms are not securely fixed with respect to the disc. -
[0006] According to the present invention there is provided a rotor disc having an array of blade slots each slot retaining a blade root, in which disc posts are defined between adjacent blade slots and annulus fillers are disposed between adjacent blade slots, each annulus filler comprising a body having an airwashed surface and an oppositely disposed chocking surface which contacts a surface of the respective disc post, the disc post having a post formation extending across the axial width of the disc post, and the annulus filler having an annulus filler formation adjacent the chocking surface which abuts both the post formation and the blade root to retain the annulus filler radially with respect to the disc; in which the chocking surface has at least one contact region (42, 44) in contact with the post formation and at least one non-contact region (24) spaced from the disc post formation. -
[0007] Each disc post may comprise a stem and a head with a larger circumferential dimension than the stem, in which case the channel walls may be directed inwardly of the channel and may engage the disc post beneath the head so that the head is firmly engaged between the channel walls and the chocking surface. The channel walls may be situated at the circumferentially outer edges of the chocking surface. -
[0008] The channel may extend over substantially the full axial extent of the disc post. In one embodiment, two of the contact regions are disposed at opposite axial ends of the chocking surface, with the non-contact region, or one of the non-contact regions, disposed between them. -
[0009] Locating means may be provided for establishing the axial position of the annulus filler with respect to the rotor disc. The locating means may comprise an abutment provided at one axial end of the respective disc post, and engaging the respective annulus filler to limit axial displacement of the annulus filler. Alternatively, or in addition, the locating means may comprise a retaining element fixed to the annulus filler at one axial end of the annulus filler, the retaining element being secured to the rotor disc by a support ring which is releasably secured to the disc. -
[0010] Another form of locating means may comprise a shear key which is fitted to the rotor disc and is accommodated within a recess in at least one of the channel walls. -
[0011] The body of each annulus filler may comprise a box section having an outer wall providing the airwashed surface, an inner wall providing the chocking surface, and oppositely disposed side walls extending between the outer wall and the inner wall. The outer wall may project circumferentially beyond the side walls, and sealing means may be provided between the circumferential edges of the outer wall and respective blades fitted in the blade slots. -
[0012] At least one of the inner and side walls may be provided with weight-saving apertures. Each annulus filler may be made from a composite material, for example a fibre reinforced material reinforced with carbon fibre, glass fibre, Kevlar or similar materials. -
[0013] The rotor may be a fan rotor of a gas turbine engine. -
[0014] The present invention also provides an annulus filler for a rotor as defined above. -
[0015] For a better understanding of the present invention, and to show more clearly how it may be carried into effect, reference will now be made, by way of example, to the accompanying drawings, in which: -
Figure 1 shows a section of a rotor disc fitted with an annulus filler; -
Figure 2 is a sectional end view of the rotor disc and annulus filler ofFigure 1 ; -
Figure 3 is a sectional side view of the rotor disc and annulus filler ofFigures 1 and 2 ; -
Figure 4 is an enlarged view corresponding toFigure 3 , showing retaining means for the annulus filler; -
Figure 5 shows a variant of the annulus filler ofFigures 1 to 4 ; and -
Figure 6 is an aft axial view of the annulus filler ofFigure 5 . -
[0016] Figure 1 shows arotor disc 2 of a fan rotor of a gas turbine engine. It will be appreciated that the rotor disc is in the form of an annulus, only part of which is shown inFigure 1 . Therotor disc 2 has a circumferential array ofblade slots 4, only two of which are shown inFigure 1 . Between the twoslots 4, there is adisc post 6, which comprises a stem orneck 8, and ahead 10 which has a larger circumferential dimension of thestem 8. -
[0017] Anannulus filler 12 is mounted on thepost 6. Theannulus filler 12 is a box-section component having a trapezoidal cross-section as shown inFigure 2 , which is a sectional view taken approximately half way along the axial length of theannulus filler 12. Thus, theannulus filler 12 has anouter wall 14, aninner wall 16, andside walls 18. Theside walls 18 extend substantially radially with respect to the central axis of thedisc 2. -
[0018] Theouter wall 14 presents anairwashed surface 20 over which flows the air stream through the fan in operation. Thecircumferential edges 22 of theouter wall 14 project in the circumferential direction beyond theside walls 18. Seals (not shown) are provided between eachedge 22 and the adjacent blade (not shown) in order to seal the gaps between theannulus filler 12 and the blades. The blades may be provided with short stub platforms which project from the blades towards theedges 22. -
[0019] Theinner wall 16 provides a chockingsurface 24 which faces the radiallyouter periphery 26 of thepost 6.Channel walls 28, which can be regarded as extensions of theside walls 18, extend from the circumferentially outer edges of thechocking surface 24. Thechannel walls 28 define, with thechocking surface 24, achannel 30 which accommodates thehead 10 of thepost 6. Thechannel walls 28 are profiled to conform closely to the contours of thehead 10, and consequently are directed inwardly of thechannel 30 towards their free edges. -
[0020] As shown inFigure 3 , thechocking surface 24 does not contact theouter surface 26 of thepost 6 at all axial locations. Theouter surface 26 is profiled to provide twopedestals recess 36, visible also inFigure 2 . Also, theinner wall 16 of theannulus filler 12 includes ajoggle 38, which means that theaft region 40 of theinner wall 16 is spaced radially outwardly with respect to theforward region 42. As shown inFigure 3 , the result is that thechocking surface 24 contacts theouter surface 26 of thepost 6 only at thepedestals channel walls 28 engage thehead 10 of thepost 6 over substantially the full axial length of thepost 6, so that theannulus filler 12 is retained on thedisc 2 in the radial direction, over the full axial length of theinner wall 16. -
[0021] By providing contact between thechocking surface 24 and theouter surface 26 only at the separate regions of thepedestals recessed region 36 between them, installation of theannulus filler 12 is assisted. Theannulus filler 12 is fitted to thepost 6 by sliding from the forward direction towards the aft direction, and the configuration shown inFigure 3 reduces the frictional resistance to this sliding movement until the raisedregion 40 of theinner wall 16 contacts theaft pedestal 34. The forward ends of thepedestals annulus filler 12 so that sequential engagement of the chockingsurface 24 first with thepedestal 32 and then with thepedestal 34 is assisted. When fitted, thehead 10 of thepost 6 is firmly engaged within thechannel 30 by the chocking action extended between the chockingsurface 24 and thechannel walls 28. -
[0022] Axial displacement of the annulus filler in the aft direction is limited by anabutment 44 on thehead 10. When theannulus filler 12 is fully installed, the aft edge of theinner wall 16 contacts theabutment 44, so defining the correctly installed position. This abutment, along with the frictional engagement created by the chocking effect between the chockingsurface 24 and thechannel walls 28, may be sufficient to retain theannulus filler 12 in the correct position on thedisc 2. Nevertheless, additional or alternative fastening measures may be employed, if required. -
[0023] Figure 4 shows an alternative securing means which may be used with, or instead of, theabutment 44. In the embodiment shown inFigure 4 , aforward extension 46 is provided on thedisc 2. Asupport ring 48 is secured to theextension 46 and extends around theentire disc 2. The support ring serves to mount further structure on thedisc 2, for example a spinner fairing which follows the line of theouter wall 14 of theannulus filler 12 and encloses the forward end of thedisc 2. -
[0024] As shown inFigure 4 , a retaining element in the form of anaxial stop lug 50 is secured, for example by adhesive bonding or integral moulding, to theinner wall 16, and is trapped between thedisc 2 and thesupport ring 48. Thestop lug 50 thus serves to prevent axial displacement of theannulus filler 12 on thedisc 2. -
[0025] Figure 5 shows an alternative retaining measure, in the form of a recess or cut-out 52 in eachchannel wall 28. In some gas turbine engines, a shear key may be provided which acts as a bridge between thedisc 2 and the root of a blade accommodated in one of theslots 4. By way of example, aslot 54 for a shear key is shown inFigure 1 . In use of the embodiment ofFigure 5 , the shear key extends into the cut-out 52, to anchor theannulus filler 12 axially with respect to thedisc 2. -
[0026] Figure 6 is a view from the aft end of theannulus filler 12 shown inFigure 5 , and illustrates the curvature which an annulus filler may have in order to conform to the profiles of adjacent blades.Figure 6 also shows weight-savingapertures 56 provided in theside walls 18 and theinner wall 16 in order to reduce the weight of the annulus filler. -
[0027] Theannulus filler 12 may be made from any suitable material such as an aerospace metallic alloy or a composite material. The configuration of theannulus filler 12 lends itself particularly to manufacture from a composite material, for example by lay-up using pre-impregnated pre-forms, or dry pre-forms impregnated with resin in a resin transfer moulding process, or using automated fibre placement techniques. The composite material may comprise carbon fibre, glass fibre, or Kevlar reinforcements. If carbon fibre is used, provision for protection against galvanic corrosion will be required where theannulus filler 12 interfaces with aluminium alloy components. -
[0028] Theannulus filler 12 could alternatively be manufactured by an extrusion operation followed by pultruding or hydroforming to shape, or by injection moulding. -
[0029] An annulus filler as described above is locked firmly with respect to thedisc post 6, and is further retained in position by blade roots accommodated in theblade slots 4 on assembly of the complete fan rotor. Radial loading on theannulus filler 12 is distributed over the full axial length of thedisc post 6, so reducing stresses in theannulus filler 12 and enabling significant weight savings. As shown inFigure 2 , theside walls 18 extend radially of thedisc 2, with the result that theside walls 18 are able to withstand centrifugal forces without bending stresses, further enabling weight reduction. -
[0030] Incorrect fitting of theannulus filler 12 is difficult and, if mis-fitting occurs, is visually noticeable. -
[0031] The geometry of theannulus filler 12 described above is relatively simple compared with known annulus filler components, and consequently manufacturing costs can be reduced. Similarly, the elimination of any requirement for projecting features at the periphery of thefan disc 2 reduces the diameter of the fan disc forging, and reduces the time required for machining complex features such as retaining hooks. Where a shear key is provided, the absence of any hook feature provides greater freedom for the positioning of the shearkey slot 54, since it is not necessary to avoid alignment of the shear key slot with the hook features. -
[0032] As shown inFigure 6 , theannulus filler 12 need not be straight, but could be arcuate, provided that the general cross-section of thedisc post 6 is substantially constant over its full length. The local flexibility of the annulus filler can be controlled by varying the thickness of the cross-sections of the outer andinner walls side walls 18 in order to accommodate blade rock. -
[0033] Appropriate formations may be provided on theannulus filler 12, such as pips, bumps or ridges, in order to avoid water retention and to mitigate contact fretting. -
[0034] Although the annulus filler described above comprises thechannel 30 which accommodates thehead 10 of thedisc post 6, other means of retaining theannulus filler 12 radially with respect to thedisc 2 may be employed. For example, thepost 6 may be a secondary dovetail or retaining post in or on thehead 10 for engagement by a complementary formation provided on theannulus filler 12 adjacent the chockingsurface 24.
Claims (15)
Hide Dependent
translated from
- A rotor comprising a rotor disc (2) having an array of blade slots (4) each slot retaining a blade root, in which disc posts (10) are defined between adjacent blade slots and annulus fillers (12) are disposed between adjacent blade slots, each annulus filler comprising a body having an airwashed surface (20) and an oppositely disposed chocking surface (24) which contacts a surface of the respective disc post, the disc post having a post formation (26) extending across the axial width of the disc post, and the annulus filler having an annulus filler formation (28) adjacent the chocking surface which abuts both the post formation and the blade root to retain the annulus filler radially with respect to the disc; in which the chocking surface has at least one contact region (42, 44) in contact with the post formation and at least one non-contact region (24) spaced from the disc post formation.
- A rotor as claimed in claim 1, in which the annulus filler formation comprises a pair of channel walls (28) extending from the chocking surface and defining with the chocking surface a channel which receives the respective disc post.
- A rotor as claimed in claim 2, in which the disc post comprises a stem (8) and a head (6) with a larger circumferential dimension than the stem.
- A rotor as claimed in claim 3, in which the channel walls are directed inwardly of the channel and engage beneath the head of the disc post.
- A rotor as claimed in any one of claims 2 to 4, in which the channel walls extend from circumferentially outer edges of the chocking surface.
- A rotor as claimed in any one of claims 2 to 5, in which the channel extends substantially the full axial extent of the disc post.
- A rotor as claimed in any preceding claim, in which two of the contact regions (32, 34) are disposed at opposite axial ends of the chocking surface, with the non-contact region, or one of the non-contact regions, disposed between them.
- A rotor as claimed in any one of the preceding claims, in which an abutment (44) is provided at one axial end of the disc post, the annulus filler engaging the abutment to limit axial displacement of the annulus filler.
- A rotor as claimed in any one of the preceding claims, in which a retaining element (50) is provided at one axial end of the annulus filler, the retaining element being engaged by a support ring (48) which is releasably secured to the rotor disc.
- A rotor as claimed in any one of the preceding claims, in which a shear key is fitted to the rotor disc and is accommodated in a recess (52) in the annulus filler.
- A rotor as claimed in any one of the preceding claims, in which the body comprises a box section having an outer wall providing the airwashed surface, an inner wall providing the chocking surface, and side walls extending between the inner wall and the outer wall.
- A rotor as claimed in claim 11, in which the outer wall projects circumferentially beyond the side walls.
- A rotor as claimed in claim 11 or 12, in which at least one of the inner and side walls is provided with weight-saving apertures.
- A rotor as claimed in any one of the preceding claims, in which the annulus filler is made from a composite material.
- A rotor as claimed in any one of the preceding claims which is a fan rotor of a gas turbine engine.