GB2397854A

GB2397854A - Securing blades in a rotor assembly

Info

Publication number: GB2397854A
Application number: GB0302153A
Authority: GB
Inventors: David John Chisholm
Original assignee: Rolls Royce PLC
Current assignee: Rolls Royce PLC
Priority date: 2003-01-30
Filing date: 2003-01-30
Publication date: 2004-08-04
Also published as: GB0302153D0

Abstract

In a rotor assembly, such as a compressor or turbine for a gas turbine engine, a plurality of blades 24, are mounted on a rotary support member, such as a disc 22, by means of roots 28, on the blades, which may be received within axially extending grooves 32, in the disc. In order to secure the blades and prevent axial movement, receiving means, such as circumferentially extending grooves 36, 38, are formed in the blade roots and the disc, and at least a portion of a securing means, such as a circumferential securing member 34, is received therein. The securing member may comprise a slot 40, with a profile corresponding to that of a blade root, whereby the member, when rotated to align the slot 40, with a groove 32, allows a blade root to be inserted into the groove 32. The securing member 34, may comprise a split ring with interlocking end portions, and a clip 42, may be provided to fasten the securing member 34, against rotation once all the blades have been loaded.

Description

A ROTOR ASSEMBLY

This invention relates to rotor assemblies. More particularly, but not exclusively, the invention relates to rotor assemblies for use in gas turbine engines, for example compressors or turbines.

Compressors of gas turbine engines comprise a plurality of compressor blades which are removably mounted on a compressor disc. The blades can be mounted on the disc by means of a circumferentially extending groove or by means of axially extending grooves. In the case of axially extending grooves, the blades are retained on the disc by the use of segmented parts at the downstream or upstream faces of the disc. This has the disadvantage that it can lead to high stresses in the root.

According to one aspect of this invention, there is provided a rotor assembly comprising a rotary support member, a plurality of rotor blades mounted circumferentially around the support member, and attending radially therefrom for rotation with the support member, and securing means for securing the blades to the support member, wherein each blade includes a root for mounting the blade on the support member, the root including a first receiving means, and the support member including a second receiving nouns, and each of the first and second receiving means being arranged to receive at least a portion of th: securing means therein.

Preferably, the first receiving means is in the form of a recess defined by the blade root. The recess defined by the blade root is preferably a groove extending through the blade root, through which the securing means can extend. Preferably, the recess defined by the blade root extends generally centrally through the blade root.

The second receiving means is preferably in the form of a recess defined in the support member.

The recess in the support member is preferably a groove which extends at least partially, and preferably substantially wholly, cacumferentially around the support member. Preferably, the recess defined by the support member extends generally centrally around the rim of the support member.

Desirably, the securing means comprises a securing member which can be received by the receiving means of at least one blade. Preferably, the securing ripener can be received by Me receiving means of a plurality of blades. Conveniently, said plurality of blades are all the blades on the support / member.

Advantageously, the securing member is generally annular in configuration, and may extend substantially wholly around the support member to secure each blade to the support member.

The support member may define a plurality of blade receiving grooves extending axially through the support member, to receive a portion of each blade therein. Preferably, the portion so received by the blade receiving grooves is the root of each respective blade. Each blade receiving groove preferably also extends radially inwardly from the rim of the support member. The securing member may extend through said blade receiving grooves and may define a slot to allow the mounting of the blades on to the support member in said blade receiving grooves.

Preferably, the securing member is circumferentially rotatable relative to the support member to bring each blade receiving groove in the support member into alignment in turn with the slot in the securing member to allow the blades to be received in the blade receiving grooves in the support member.

The securing member may be in the form of a split ring having overlapping opposite end regions to facilitate mounting the securing member on the support member. Preferably the end regions co- operate with each other to provide said annular configuration of the securing member Fastening means may be provided to fasten the securing member to the support member.

Preferably, the fastening means comprises a clip which engages the blade and the support member.

Preferably, the fastening means engages the blade at one end region thereof' and may engage the support member at the opposite end region thereof. The fastening means may extend through the slot in the securing member to engage a downstream or upstream face of the support member. Preferably, the groove in the support member is generally centrally defined along a rim region thereof.

The rotor assembly is preferably a comlxessor stage, or it may be a turbine stage.

According to another aspect of this invention there is provided a method of assembling a rotor assembly comprising providing a plurality of rotor blades each including a root for mounting the blade on the support memba, the root including first receiving means, providing a rotary support member ? including a second receiving means, providing securing means for securing the blades to the support mender and arranging the securing means on do support member such that each of the first and second receiving means receive a portion of the securing means.

The securing means may comprise a securing member which can be received by the first receiving means of at least one blade and, preferably, by the receiving means of a plurality of said blades. Said plurality of blades conveniently comprises all the blades on the support member.

The support member may include a plurality of axially extending blade receiving grooves and the method may include arranging the securing member on the support member such that the securing mender extends through the blade receiving grooves, preferably extending circumferentially hehrough.

The securing member preferably includes a slot to allow the mounting of the blades on to the support member. The method may include the step of aligag the slot with one of Me blade receiving grooves and sliding a portion of one of the blades into the blade receiving groove, said step of sliding a portion of the blade into the blade receiving groove including sliding said portion through the slot. The method may further include the step of sliding the securing member relative to the support means along the second receiving means until the slot is aligned with a further blade receiving groove in the support member to enable a further blade to be received therein. Thereafter the method may further mclude repeating the last step until all the blades are received in the blade receiving grooves.

The securing member may be circumferentially rotatable about the support member. Preferably, the steps of sliding the securing member along the second receiving means includes circumferentially rotating the securing member relative to the support member to bring each blade receiving groove into alignment in turn with the slot in the securing member to allow the blades to be received in the blade recerving grooves in the support member.

The securing member may be in the form of a split ring having opposite end regions which coquette with each other to provide said angular configuration. The method may include the step of installing the securing member on the supper member. The step of installing the securing member may choose separating the opposite end regions from each other arranging the securing member around the ) support member in the second receiving means and arranging the opposite ends in cooperative engagement with each other.

The method may further include the provision of fastening means to fasten the securing member to the support member. ARor said step of arranging all the blades in the blade receiving grooves on the support member, the method may further include arranging said fastening means to engage the blade and the support member. Preferably, the method includes arranging the fastening means to engage the blade at one end region of the fastening means and may include arranging Me fastening means to engage the support member at the opposite end region of the support member.

The fastening means may comprise a clip and may be arranged to extend through the slot in the securing member, thereby preventing sliding of the securing member along said second receiving means.

The fastening means may be arranged to engage a downstream or upstream face of the support member.

An embodiment of the invention will now be described by way of example only, with reference to the accompanying drawings, in which; Fig. I is a cross-sectional side view of the upper half of a gas turbine engine; Fig. 2 is a perspective view of a blade; Fig. 3 is a part cross-sectional view showing a blade mounted as a support member; Fig. 4 is a view of a region of a securing member; and Fig. 5 is a part cross sectional view axially of a support member showing the securing member.

Referring to Fig. 1, a gas turbine engine is generally indicated at 10 and comprises, in axial flow series, an air intake 11, a propulsive fan 12, an intermediate pressure compressor 13, a high pressure compressor 14, a combuar IS a turbine arrangement comprising a high pressure turbine 16, an mediate pressme turle 17 and a low presume turbine 18, and an exhaust nozzle 19. f

The gas turbine engine 10 operates in a conventional manner so that air entering the intalce I I is accelerated by the fan 12 which produces two air flows: a first air flow into the intermediate pressure compressor 13 and a second sir flow which provides propulsive thrust. The intermediate pressure compressor congresses the air flow directed into it before delivering that air to the high pressure compressor 14 where further compression take place.

The compressed air exhausted from the high pressure compressor 14 is directed into the combustor 15 where it is mixed with fuel and the mixture combusted. The resultant hot combustion products then expand through and thereby drive the high, intermediate and low pressure turbines 16, 17 and 18, before being exhausted through the nozzle 19 to provide additional propulsive thrust. The high, intermediate and low pressure turbines 16, 17 and 18 respectively drive the high and intermediate pressure compressors 14 and 13 and the fan 12 by suitable interconnecting shafts.

Referring to Figs. 2-5, there is shown various components of a rotor assembly for use in a gas turbine engine. In the embodiments shown, the rotor assembly is a stage 20 of one of the compressors 13 or 14, and comprises a blade support disc 22 upon which are mounted a plurality of radially outwardly extending compressor blades 24.

Each blade 24 comprises an aerofoil section 26, a platform 27, and a blade root 28. The disc 22 defines. at its radially outer rim region 30 a plurally of axially extending blade receiving grooves 32 into which the blade root 28 is slid in an axial direction to secure the blades 24 to the disc 22.

In order to secure the blades 24 within the respective blade receiving groove 32 and prevent asocial movement of the blades 24, an annular securing member 34 is provided which extends oirmtially around the disc 22. For this purpose, the disc 22 defines a circumferentially extending groove 36 which extends wholly around the rim region 30 of the disc 22. The securing runnber 34 is received within the circurnferendally extending groove 36 in the disc 22.

As can be seen from Fig. 2, the blade root 28 of each of the blades 24 defines a groove 38 i., he root 28. the purpose of the groove ..

38 receive therein a radially outer portion of the securing member 34. Thus, the circumferentially w. ., ,,, j: S rt. l

extending securing member 34 extends through the groove 36 in the disc 22 and through the respective groove 38 in the root 28 of each of the compressor blades 24 mounted on the disc 22.

In order to assemble the blades 24 on to the disc 22, the securing member 34 is provided with a radially extending slot 40 which is shaped to correspond to the profile of the blade root 28 when viewed in an axial direction. The securing member 34 is first rotated about the disc 22 in one of the two directions indicated by the double headed arrow A until the slot 40 is aligned with one of the axially extending blade receiving grooves 32 in the disc 22.

A blade 24 can then be slid through the slot 40 and into the blade receiving groove 32 with which the slot 40 is aligned, until the groove 38 is aligned with the groove 36, thereby allowing father circumferential rotation, as indicated by the arrow A of the securing member 34.

The securing rnembe,r 34 is further rotated until the slot 40 is aligned with another of the blade receiving grooves 32, for example the adjacent blade receiving groove 32 and, thereafter, a further blade 24 can be slid through the slot 40 into the further blade receiving groove 32, until the groove 38 in the blade root 28 is aligned with the groove 36 in the disc 22. This process can then be repeated until all the blades 24 are assembled on to the disc 22.

The securing member 34 is then rotated circumferentially so that the slot 40 is arranged between adjacent blade receiving grooves 32, and fastened at this position by the use of fastening means 42. This prevents circumferential rotation of the securing member 34 during operation of the compressor, thereby preventing the slot 40 aligning itself with one of the blade receiving grooves 32 which could result in the blade 24 held at that blade receiving groove 32 to be released from the disc 22.

The fastening means 42 comprises a clip having a generally planar main portion 43 and opposite end regions 44, 46 deformed transversely therefrom in opposite directions. The -I legion 44 engages a rsWly inwardly extending projection 48 on Me platform 27, and the end region engages either the upstream face 50, or the downstream face 52 of the disc 22. in the embodiment shown, the end region 46 enlarges the upstream face 50 of the disc 27.

À -- i?; + it - !' The clip ago lot ludes a radially outwardly extending projection 54 which engages the platfonns --i>Xj,si.: 27 of adjacent blades 24. r - 7

The securing member 34 is in the form of a split ring having opposite end regions 56, 58. The end regions 56, 58 comprise interlocldog portions 60, 62, which enable the ends 56, 58 to be separated from each other so that the securing member 34 can be installed into the groove 36 in the disc 22 and, theater, interlocked with each other to secure the opposite end regions 56, 58 together.

Them is thus described a rotor assembly in the form of a compressor stage of a gas turbine engine in which the blades can be secured on to the compressor disc in a simple and easy manner, without the need for complex securing means or the like. The preferred embodiment has the advantage Mat stresses are reduced because the securing means is located in a region of the disc away from peak stresses. The precise position of the securing means on the disc can be varied to suit the characteristics of the blade A further advantage of the preferred embodiment of the invention is that, since the securing member 34 extends substantially continuously around the disc, it provides a sealing effect, thereby preventing the leakage of air in an upstream direction across the compressor.

Various modifications can be made without departing from the scope of the invention, for example, It rotor assembly could be a turbine.

Whilst endeavouring in the foregoing specification to draw attention to those features of the invention believed to be of particular importance it should be understood that the Applicant claims protection in respect of any patentable feature or combination of features hereinbefore referred to anchor shown in the drawings whether or not particular emphasis has been placed thereon At. . . Hi, , I: - ,.-, ; : :. ,(,

Claims

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Cl,AIM S 1. A rotor assembly compri<:n a rotary support member, a plurality of rotor blades mounted circumferentially around the Support member, and extending radially therefrom t'oT rotation with the support member, and securing means for securing the blades to the support member, wherein each blade includes a root for mounting the hl:de on the support member, the root including a f first r ecci\,ing means, and the support membcT- including second receiving means. and each of the fit rst and second receiving means being unranked to receive at 'east a poTtion of t'hc securing means therein.
2. A rotor assembly according to Claim 1 wherein the first receiving means is in the torm of a recess defined by the blade root and the second receiving means is in the form of a recess defined in the support member.
3. A rotor assembly according to Claim 2 wherein the recess defined by the bla:le root is a groove extending thTough the blade root. through which the securing means can extend, and the recess in the support member is a groove which extends at least partially circumferen:!ally around the support member.
4. A rotor assembly according to Claim 3 wherein the recess defined by the blade root extends generally centrally through the bloc root, the recess defined by the support ncmbcr extends generally centrally around the rim of the support member.
5. A rotor assembly according to any preceding (: laim wherein the securing meaTls comprises a securing member which can be received by the receiving means of at least one blade.
6. A rotor assembly according to Claim 5 wherein the securing member can be received by the receiving means of substantially all the blades on the support member.
7. A rotor assembly according to Claim 6 wherein the securing member is generally annular in configuration, and extends substantially wholly around the support member to secure each blade to the support member.
8. A rotor assembly according to Claim 6 or 7 wherein the support rrmnber defines a plurality of blade receiving grooves extending axially through the support member, to receive the root of each blade therein, the securing member extending through said blade receiving grooves, and said securing men-.ber defining a slot to allow the mounting of the blades on to the support member in said blade receiving grooves.
9. A rotor assembly according to Claim 8 wherem the securing member is circumferentally rotatable relative to the support member to bring each blade receiving groove in the support member into alignment in rum with the slot in the securing member to allow the blade roots to be received in the blade receiving grooves in the support member.
10. A rotor assembly according to Claim 8 or 9 wherein fastening means is provided to fasten the securing member to the support member.
I I. A rotor assembly according to Claim 10 wherein die fastening means comprises a clip to engage the blade and the support member.
12. A rotor assembly according to Claim 10 or I I v.erein the fastening means engages the blac. at one end region thereof, and engages the support member at the opposite end region thereof, the fastening means extending through the slot in the securing member to engage a downstream or upstream face of the support member.
13. A rotor assembly according to any preceding Claim wherein the groove in the support member is generally cent- lly defined along a rim region thereof:
14. A rote- assembly according to any preceding Clam wherein the securing member is in the form of a split ring having overlapping end regions to facilitate mounting the securing member on the support member.
15. A method of assembling a rotor assembly comprising providing a plurality of rotor blades each including a root for mounting the blade on the support member, the root including first receiving means, providing a rotary support member including a second receiving means, providing securing means for securing the blades to the support member and arranging the securing means on the support member such that each of the first and second receiving means receive a portion of the securing means.

J
16. A method according to Claim- 15 wherein the securing means comprises a securing member which can be receive i by the first receding means of at least one blade.
17. A method:cording to C'lain 16 wherein the securing member can be received by the first receiving means of substantially all ot'said blades on the support member.
18. A method ccordiny to C'ia,-- 17 wherein the support member includes a plurality of axially extending blade regiving grooves..-d the method Encodes arranging the earing member on the support member so; r. that the secure. member extends through the blade recei\ ;-: g grooves.
19. A method according to Clan-, 18 wherein the securing member includes a slot to allow the mounting of' the blades on to the support member, and the method includes the Rep of aligning the slot with one ol'the blat receiving groom- s and sliding the root of one of the blades:nto the blade receiving groove, said step o.'sliding the root:-.to the blade receiving groove including shding said root through the slot.
20. A method ccording to Claim 19 wherein the method further includes the step of sliding the securing member relative to the support means along the second receiving --cans until the she is aligned with a Further blade receiving groove in the support member to enable further blade to received therein.
21. A method ccording to C!aim JO wherein the method further includes repeating the step defined in Claim 20 until a:: the blades are received in the blade receiving grooves.
22. A method according to Claim 20 or 21 wherein the securing member is circumferentially rotatable about the support member. and the step of sliding the securing member along the second receiving means includes circumfere..tially rotating the securing member relative to the support member to bring each blade receiving groove Into alignment in turn with the slot in the securing member to allow the blades to be received in the blade receiving grooves in the support member.
23. A method according to any ot'Claims 16 to 22 wherein the securing member is in the form of a split ring having opposite end regions which cooperate with each other to provide said annular configuration, and the method includes the step of installing the securing member on the support member l] b! separating the opposite end regions *om each other a-angina the securing no Her around the support member in the second receiving means and arranging the opposite ends in cooperative engagement with each other.
2 I. A method according to any of Claims 16 to 23 wherein the method further incl des the provision of t'astening means to fasten the securing member to the support member, and said step of arranging all the blades in the blade receiving grooves on the support me:-aer, the method further:-ludes an-angina said fastening means to engage the blade and the support mer.-.er.
25. A method according to Claim 24 herein the method includes arranging the: stening means to engage the blade at one end region of the fastening means end further includes array. :ng the fastening means to engage the support member at the opposite end region of the support membe
26. A method according to Claim 24 or 25 wherein the. stening means comprises clip arranged to extend through the slot in the securing member, thereby pre\ eating sliding ol' the secu--ng member along said second receiving means, and being arranged to enga e a downstream or up;--eam face of the support member.
27. A gas turbine engine incorporating a rotor assembly according to any of Clain:s I to 14.
28. A rotor assembly substantially as herein described with reference to F: I. 2 to S of' the accompanying dray ings.
9. A method of assembling a rotor assembly subs ar- lily as herein describe with reference to Figs. 2 to S of the accompanying drawings.
30. Any novel subject matter or combination including novel subject matter disclosed herein, whether or not w ithin the scope of or relating to the same ins ention as any of the preceding claims.