GB2084261A

GB2084261A - Mounting compressor stator blades

Info

Publication number: GB2084261A
Application number: GB8031442A
Authority: GB
Original assignee: Rolls Royce PLC
Current assignee: Rolls Royce PLC
Priority date: 1980-09-30
Filing date: 1980-09-30
Publication date: 1982-04-07

Abstract

A compressor has an annular array of stator vanes 14 whose radially outer ends are supported by a ring 20 clamped axially between two flanges 17 (19, Fig.2 not shown), of casing 11. The end of each blade 14 has an extension 27 engaged in a respective axial slot 26 in the ring 20 at the inner periphery thereof. At its outer periphery the ring 20 has circumferentially continuous axial side faces 22, 23 engaged by the flanges 17 (19) to ensure sealing. Rubber blocks 32, disposed between confronting sides of the extension 27 and slot 26 ensure vibration damping. The arrangement may be repeated at the radially inner ends of the vanes. <IMAGE>

Description

SPECIFICATION Bladed axial flow compressor This invention relates to a bladed axial flow compressor and is concerned with supporting an annular array of stator vanes of the compressor.

The invention applies to the situation where the vanes of the array are separate components, either in the form of single vanes or in the form of segments of two or more vanes, held together by an annular continuous structure, e.g. a casing surrounding the array. It is known to assemble single vanes by entering the ends of the vanes in an undercut circumferential groove at the inside of the casing but this creates the difficulty of having to provide the groove with a mouth through which to enter the vanes into the groove. Also there may be fretting due to the necessary clearances between the ends of the vanes and the groove.

This difficulty can in certain cases be overcome by making the casing in two parts joined at a plane transverse to the axis of the array and to clamp the array axially between said parts. This has in the past required the array to be a unitary structure, e.g. in the form of a single casting. However, a unitary structure is not always appropriate, e.g. in the case of very large vanes or where it is desirable to be able to replace the vanes individually, or where it is desirable to provide a vibration damping means between the vanes and the casing. It is an object of this invention to provide an axial flow bladed compressor in which single said vanes, or segments of said vanes, can be supported between axially joined parts of a casing or other support structure.

The scope of this invention is defined in the claims hereto.

An example of an axial flow compressor according to this invention will now be described with reference to the accompanying drawings wherein: Fig. 1 is a diagrammatic side view of a gas turbine engine embodying the compressor.

Fig. 2 is an enlarged detail of Fig. 1.

Fig. 3 is a view in the direction of an arrow III in Fig. 2.

The compressor, denoted 10, extends annularly about an axis 1 0a and is contained in an outer casing 11 (Fig. 1). Further the compressor 10 is arranged in flow-series with a combustor 12 and a turbine 1 3 connected to drive the compressor 1 0.

The compressor 10 comprises an annular array of stator vanes 1 4 supported at their radially outer ends by a support generally denoted 15 comprising two annularly continuous and axially adjacent parts 1 6, 18 (Figs. 2, 3) of the casing 11.

The parts 16, 1 8 have respective mutually confronting flanges 17, 19, between which is situated a ring 20. Bolts 24 are provided to clamp the flanges 17, 19 into engagement with the ring.

At its radially outer periphery 21, i.e. the periphery remote from the vanes 14, the ring 20 has circumferentially continuous axial end faces 22, 23 having circumferentially continuous engagement with the flanges 17, 1 9 respectively.

The pressure applied by the bolts 24 ensures a sealing engagement between the flanges 1 7, 1 9 and the end faces 22, 23 against the escape of pressure from with the casing 11. At its radially inner periphery 25, i.e. the periphery adjacent the vanes 14, the ring 20 has, in respect of each vane 14, an axial recess or slot 26 which is open to the periphery 25 and to the axial sides of the ring.

Each vane 14 has at its radially outer end, i.e.

the end adjacent the ring 20, an extension 27 engaging a respective one of the slots 26.

Circumferentially facing side faces 28, 30 of the extension confront respective side faces 29,31 of the slot. Each pair of confronting side faces 28, 29 and 30, 31 has therebetween a block 32 of resilient material e.g. rubber. The side faces 28, 29 and 30, 31 co-operate to support the vane 14 against circumferential displacement. A portion 33 of the extension 27 at the free radial end thereof is widened circumferentially and the slot 26 has a complementary widened bottom portion 34 so that the side faces 28, 29 and 30,31 cooperate to support the vane 14 against withdrawal from the slot in the radial direction.

The blocks 32 are arranged to be in firm engagement with the faces 28, 29 and 30, 31 and so provide resilience against torsional vibrations of the vane as well as resilience against radial withdrawal forces. The latter forces occur when the blade bends circumferentially under the fluid pressure forces thereon.

The vane 14 includes an integral platform 35 arranged between the extension 27 and the aerofoil body, 36, of the vane. The platform 35 helps to form what could otherwise be a difficult transition from the shape of the aerofoil body 36 to the possibly dissimilar shape of the extension 27. The platforms 35 have radially inwardly facing surfaces 39 defining a boundary of the flow passage, 38, through the compressor.A recess 40 is defined by upstream ends 42 of the platforms and an inner surface 43 of the upstream one 1 6 of the parts 1 6, 18 to accommodate the radially outer extremities of an annular array of rotor blades 41 provided adjacent the vanes 1 4. The platforms have radially outwardly facing surfaces 44 having the closest practicable proximity with the surface 43 and a corresponding surface 45 of the part 18, the surfaces 44, 45 being in alignment.

The radially inner ends of the vanes 14 are provided with a support 1 5A which is similar to the support 1 5 and has two annularly continuous parts 1 6A, 1 8A clamped by bolts 24A on to a ring 20A. The latter has at a radially inner periphery 21 A thereof circumferentially continuous end faces 22A, 23A sealingly engaged by confronting flanges 1 7A, 1 9A of the parts 1 6A, 1 8A. Slots 26A at the outer periphery 25A of the ring 20A each receive an extension 27A provided at the radially inner end of a respective one of the vanes 14.

Blocks 32A of resilient material are provided between confronting side faces of the extension 27A and the recess 26A all substantially as described for the support 1 5, except that the support 1 5A serves to connect the vanes together at their inner ends to provide stability for the array as a whole and to further assist in damping vibrations. The parts 1 6A, 1 8A also support seals 46A, 47A between the stator array and an adjacent rotor 48.

In a modification the support 15A is replaced by a known support or the vanes 1 4 are left free at their inner ends. In a further modification the support 1 5 is replaced by a conventional connection between the vanes 14 and the casing 11.

In order to ensure that the ring 20 is gripped between the parts 1 6, 1 8, it is in practice unavoidable to make the axial extent of the extension 27 slightly smaller than the axial extent of the ring 20 so that a clearance may occur at the confronting surfaces of the extension 27 and the flanges 1 7, 1 9. This is not necessarily harmful but insofar as the blocks 32 are provided, axial movement of the vanes through said clearance is prevented or inhibited. The bolts 24 must of course be so positioned that the force applied by them is effective at the surfaces 22, 23 of the ring 20 to ensure sealing. However, the bolts 24 may be situated in positions circumferentially between adjacent extensions 27 substantially as shown in Fig. 3.

It will be seen that the invention makes it possible to support single vanes 14 axially between the circumferentially continuous parts 1 6, 18; that any difficulty which may arise in connection with radial sealing between the parts 16, 18 is avoided by the intermediary of the circumferentially continuous surfaces 22, 23 of the ring; that damping sf the vane 14 is provided for by the blocks 32; that the vanes 14 are individually replaceable by removal from the ring 20; and that the array of vanes as a whole can be assembled readily as a unit by virtue of the vanes being held together by the ring 20. The part played by the ring 20A and the parts 1 6A, 1 8A is in essence the same.

Generally, the term "vane" is understood to include a segment comprising two or more, say three, vanes having inner and outer platforms in common. In such a case an extension, such as the extension 27, may extend over the whole circumferential length of the platform or, say, two such extensions may be provided in circumferentially spaced apart relationship to allow a bolt, such as a said bolt 24, to be introduced in a position intermediate between the circumferential length of the platform.

It will be clear that the rings 20, 20A lie in planes which are transverse to the axis 1 OA; that the ring 20 and the parts 16, 18 define an axial joint of the casing 11; and that the ring 20A and parts 1 6A, 1 8A define an axial joint of the support 15A.

Claims

1. Axial flow compressor having an annular array of stator vanes supported at their radially outer ends by a support comprising two annularly continuous, axially adjacent, parts of an outer casing of the compressor, the parts having respective mutually confronting flanges, a ring situated between the flanges, means for clamping the flanges into engagement with the ring, the ring having at its radially outer periphery circumferentially continuous engagement with the flanges, the ring having an annular array of slots at its radially inner periphery, each slot being open to said inner periphery and to the axial sides of the ring, each said vane having at the radially outer end thereof an extension engaging a respective said slot, the extension having side faces confronting respective side faces of the slot and cooperating therewith to support the vane against circumferential displacement, and the extension having end faces confronting the respective said flanges and cooperating therewith to support the vane against axial displacement.

2. Axial flow compressor having an annular array of stator vanes supported at their radially inner ends by a support comprising two annularly continuous parts having respective mutually confronting flanges, a ring situated between the flanges, means for clamping the flanges into engagement with the ring, the ring having at its radially inner periphery circumferentially continuous axial end faces having circumferentially continuous engagement with the flanges, the ring having an annular array of slots at its radially outer periphery, each slot being open to said outer periphery and to the axial sides of the ring, each said vane having at the radially inner end thereof an extension engaging a respective said slot, the extension having side faces confronting respective side faces of the slot and co-operating therewith to support the vane against circumferential displacement, and the extension having end faces confronting the respective said flanges and co-operating therewith to support the vane against axial displacement.

3. Axial flow compressor having an annular array of stator vanes supported at their radially inner and outer ends by respective supports each comprising two annularly continuous parts having respective mutually confronting flanges, a ring situated between the flanges, means for clamping the flanges into engagement with the ring, the ring having at its periphery remote from the vanes circumferentially continuous axial end faces having circumferentially continuous engagement with the flanges, the ring having an annular array of slots at its periphery adjacent the vanes, each slot being open to said adjacent periphery and to the axial sides of the ring, each said vane having at its end adjacent the ring an extension engaging a respective said slot, the extension having side faces confronting respective side faces of the slot and co-operating therewith to support the vane against circumferential displacement, and the extension having end faces confronting the respective said flanges and co-operatgin therewith to support the vane against axial displacement.

4. Compressor according to any one of claims 1, 2 or 3, wherein the extension has at its free end a widened portion, the recess has a widened bottom portion, and the portions co-operating to resist withdrawal of the extension from the recess.

5. Compressor according to any one of the preceding claims, comprising resilient bodies arranged between confronting sides of the slot and of the extension.

6. Compressor according to any one of the preceding claims, each said vane comprising a platform arranged between said extension and an aerofoil body of the vane, the platforms of adjacent said vanes being in mutual circumferential proximity and having radially facing surfaces defining a boundary of the flow passage through the compressor.

7. Compressor according to claim 6 as dependent on claim 1, the platforms having radially outwardly facing surfaces proximate with annular inner surfaces of the respective said casing parts, the upstream ends of the platforms defining an annular recess with the inner surface of the upstream one of the parts, and an annular array of rotor blades having radially outer extremities extending into said recess.

8. Axial flow compressor substantially as described herein with reference to the accompanying drawings.