GB2416568A

GB2416568A - Aerofoil with support member

Info

Publication number: GB2416568A
Application number: GB0416542A
Authority: GB
Inventors: John White; Peter Thomas Spittle; Simon John Westbrooke; Philip Richard Kelk; Kay Donnelly; Stuart Ellis; Ian Clayton
Original assignee: Rolls Royce PLC
Current assignee: Rolls Royce PLC
Priority date: 2004-07-24
Filing date: 2004-07-24
Publication date: 2006-02-01
Also published as: GB0416542D0

Abstract

An aerofoil 22, such as a turbine or compressor blade, is supported by a support member 24 which defines a periphery. The aerofoil extends beyond the periphery. The support member may comprise a platform and the aerofoil may comprise a leading edge and a trailing edge one or both of which extend beyond a respective axially or circumferentially extending edge of the platform. Various platform shapes are disclosed and the platforms may comprise corners having bevelled edges 41 to define gaps 42 between adjacent platforms when a plurality of blades and platforms are assembled.

Description

24 1 6568 Aerofoil Arrangement This invention relates to aerofoil

arrangements. More particularly, but not exclusively, this invention relates to aerofoil arrangements for rotary components or stationary components in compressors or turbines of, for example, gas turbine engines.

Compressor blades are generally formed of an aerofoil supported on a platform. Traditionally, the blade is contained within the dimensions of the platform. Thus, for any given state of a compressor, the number of blades is limited by the circumference and the platform width. In turn, the platform width is constrained by the chord length and the stagger angle of the aerofoil of the blade.

According to one aspect of this invention, there is provided an aerofoil arrangement comprising an aerofoil, and a support member for supporting the aerofoil, the support member having a periphery, wherein the ages of the aerofoil extends beyond the periphery of the support member. Thus, in the preferred embodiment, the aerofoil overhangs the edge of the support member.

Preferably, the aerofoil has a leading edge and a trailing edge and at least one of the leading edge and the trailing edge extends beyond the periphery. Each of the trailing edge and the leading edge may extend beyond the periphery of the support member.

In one embodiment, the support member may have opposite sides. In this embodiment, the sides may be generally straight and may be parallel to each other. The edge, or each of said edges, may extend beyond a respective one of said sides. The support member may have two pairs of opposite sides. Each of the sides may be generally straight, and the sides of each respective pair may be parallel to each other. In one embodiment for use in a gas turbine engine, the support member comprises axially extending opposite sides. Alternatively, or in addition the support member, may comprise circumferentially extending opposite sides.

The support member may comprise a platform, which may be generally of a rectangular configuration. In other embodiments, the support member may be of a configuration other than rectangular. For example the platform may be skewed or stepped. Where the aerofoil arrangement is for use in a gas turbine engine, the platform may comprise opposite axially extending sides, and opposite circumferentially extending sides. The leading and trailing edges of the aerofoil may, in one embodiment, extend over the axially extending sides, and in another embodiment, the leading and trailing edges of the aerofoil may extend over the circumferentially extending sides.

In another embodiment, the support member may define at least one bevel edge, which may define gap region, wherein, in use, a leading or trailing edge of an adjacent aerofoil extends over the gap region.

Preferably, the, or each, gap region of the support member is defined at a respective corner region of the support member.

In one embodiment, the support member may comprise at least one supporting corner region where the leading edge and/or the trailing edge of the aerofoil may extend beyond the respective side of the support member, and at least one non-supporting corner region of the support member, may be provided adjacent the, or each, supporting corner region of the support member, wherein the, or each, gap region is defined at respective non-supporting corner region.

The gap regions maybe defined diagonally opposite each other. It will be appreciated by the skilled person that the gap regions need not be diagonally opposite each other, if desired. The gap regions could be provided in any other suitable relationship to each other.

According to another aspect of this invention, there is provided an assembly comprising a plurality of aerofoil arrangements as described above arranged in succession adjacent each other.

Preferably, where a gap region is defined between adjacent aerofoil arrangements, a leading edge and/or a trailing edge of one aerofoil arrangement may extend over the gap region of the adjacent aerofoil arrangement.

Embodiments of the invention which now be described by way of example only, with reference to the accompanying drawings, in which: Fig. 1 is a diagrammatic view of the upper half of a gas turbine engine; Fig. 2 shows an aerofoil arrangement for use in the engine shown in Fig. 1; Fig. 3 shows a further aerofoil arrangement for use in the engine shown in Fig. 1; Fig. 4 is a diagrammatic representation of a plurality of the aerofoil arrangements provided in succession; Fig. 5 shows a further plurality of the aerofoil arrangements; and Fig. 6 shows another plurality of the aerofoil arrangements; and Figs 7 to 9 are diagrammatic top views of further embodiments of aerofoil arrangements.

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 combustor 15, a turbine arrangement comprising a high pressure turbine 16, an intermediate pressure turbine 17 and a low pressure turbine 18, and an exhaust nozzle 19.

The gas turbine engine 10 operates in a conventional manner so that air entering the intake 11 is accelerated by the fan 12 which produce two air flows: a first air flow into the intermediate pressure compressor 13 and a second air flow which provides propulsive thrust. The intermediate pressure compressor compresses the air flow directed into it before delivering that air to the high pressure compressor 14 where further compression takes 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 Fig. 2, there is shown a top plan view of an aerofoil arrangement 20, which comprises an aerofoil 22 and a support member in the form of a generally rectangular platform 24, having a periphery 25. The aerofoil 22 comprises a leading edge 26 and a trailing edge 27. The periphery 25 of the platform 24 comprises opposite axially extending sides 28, 30 and opposite circumferentially extending sides 32, 34. In the embodiment shown in Fig. 2, the leading and trailing edges 26, 27 of the aerofoil 22 extend beyond the respective opposite axially extending sides 28, 30. The aerofoil 22 has a fillet 31 which provides a curved surface joining the aerofoil 22 to the platform 24.

As can be seen from Fig. 2 the fillet 31 extends over the opposite sides 28, 30 of the platform.

The embodiment shown in Fig. 3 comprises many of the same features as the embodiment shown in Fig. 2 and these have been designated with the same reference numerals. In the embodiment shown in Fig. 3, the leading and trailing edges 26, 27 of the aerofoil 22 extend respectively over the opposite circumferentially extending sides 32, 34.

In use, the aerofoil arrangements 20 are arranged on a compressor disc and this is represented in Fig. 4 which shows an assembly 40 comprising a plurality of aerofoils 20 mounted in succession with the platforms 24 of adjacent aerofoil arrangements 20 abutting each other. As can be seen, the aerofoils 22 overlap each other, and the leading and trailing edges 26, 27 of each aerofoil 22 overhangs the platform 24 of each adjacent aerofoil arrangement 20. This would not be possible with prior art aerofoil arrangements in which the aerofoils are contained within the dimensions of the platform and, as a result, the preferred embodiment of the present invention have the advantage that for the same chord length and stagger angle of each aerofoil 22, a greater number of aerofoil arrangements 20 can be arranged on a disc than with the prior art. Alternatively, the same number of aerofoil arrangements can be provided on the disc as in the prior art, and the stagger angle can be increased over the prior art.

This provides the advantage of improving the surge margin of a compressor stage.

Referring to Figs. 5 and 6, there is shown further embodiments, in which the same features as shown in Figs. 2 to 4 have been designated with the same reference numerals.

In the embodiment shown in Fig. 5, the trailing edge 27 of each aerofoil extends over the axially extending side 28 of its platform 24 at a supporting corner region 29 of the platform 24. The adjacent aerofoil arrangement 22 which defines a gap region 42 at the non-supporting corner region 43 thereof so that the trailing edge 27 of each adjacent aerofoil extends of the gap region 42 of the adjacent aerofoil arrangement 20. Thus, as can be seen from Fig. 5, when a plurality of aerofoil arrangements 22 are arranged in succession, the trailing edge 27 of each aerofoil 22 overhangs the gap region 42 of the respective adjacent aerofoil arrangement 20. This has the advantage that, in the event of lifting of the platform 24 of an aerofoil arrangement 20, the platform 24 would not touch the aerofoil 27 of the adjacent aerofoil arrangement 20.

A similar assembly is shown in Fig. 6, in which the leading edge 26, in addition to, the trailing edge 27 extends beyond the respective axially extending sides 28, 30, at respective supporting corner regions 29A, 29B of the platform 24.

In the assembly shown in Fig. 6 each of the aerofoil arrangements define a first gap region 42 at one of the non- supporting corner regions 43A of the platform 24, and a second gap region 44 defined at the diagonally opposite non- supporting corner region 43B of the platform 24, thus, in use, when the aerofoil arrangements 20 shown in Fig. 6 are arranged on a disc, e.g. a compressor disc in succession, the trailing edge 27 of each aerofoil 22 extends over the first gap region 42 of the adjacent platform 24 of the adjacent aerofoil arrangement on one side. Also, the leading edge 26 of each aerofoil 22 extends over the second gap region 44 of the adjacent aerofoil arrangement 20 on the opposite side.

There is thus described various embodiments of an aerofoil arrangement, in which the aerofoils of each aerofoil arrangement overhang the periphery of the support member or platform to allow a greater number of aerofoil arrangements to be incorporated or to maintain the number of aerofoil arrangements, but increase the stagger angle. In some embodiments, gap regions 42, 44 are defined at one or two of the corner regions, of the platforms 24 to prevent the aerofoils 22 of the aerofoil arrangements 20 touching the platforms 24 of adjacent aerofoil arrangements 20.

The above invention has been described in connection with the compressor blades of a gas turbine engine, but it will be appreciated that it could be used in connection with nozzle guide vanes for a compressor, or with turbine blades of a gas turbine engine, or with stator vanes of a turbine.

Various modifications can be made without departing from the scope of the invention. For example, the platforms 24 can be a configuration other than rectangular, such as.skewed (e.g. as in Figs. 7 and 8) stepped (e.g. as in Fig. 9). In addition the arrangement of the aerofoil 22 on the platform 24 can be varied, for example as shown in Figs 10, 11 and 12, with fig. 12 showing a platform 24 with a single gap region 42 at one corner. It will of course be appreciated by the skilled person that the configuration of the platforms 24 can be different to that shown in the drawings. Also, the arrangement of the aerofoil 22 on the platform 24 can be different to that shown in the drawings.

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 and/or shown in the drawings whether or not particular emphasis has been placed thereon.

Claims

Claims 1. An aerofoil arrangement (20) comprising an aerofoil (22), and a

support member (24) for supporting the aerofoil (22), the support member (24) having a periphery (25), characterized in that the aerofoil (22) extends beyond the periphery (25) of the support member (24).
2. An aerofoil arrangement (20) according to claim 1 characterized in that the aerofoil has a leading edge region and a trailing edge region (26, 27) at least one trailing of the leading and trailing edge regions extends beyond the periphery (25) of the support member.
3. An aerofoil arrangement according to claim 2 characterized in that each of the leading edge region (26) and the trailing edge region (27) extends beyond the periphery (25) of the support member (24).
4. An aerofoil arrangement (20) according to claim 2 or 3 characteried in that the support member (24) has opposite sides (28, 30, 32, 34), and one extends beyond a respective one of said sides.
5. An aerofoil arrangement (20) according to claim 4 characterized in that the support member (24) has a pairs of axially extending opposite sides (28, 30), and one, or each, edge regions (26, 27) of the aerofoil (22) extend beyond a respective axially extending side (28, 30).
6. An aerofoil arrangement according to claim 4, characterized in that the support member (24) has a pair of circumferentially extending opposite sides (32, 34), and one, or each, edge region (26, 27) of the aerofoil (22) extend beyond a respective circumferentially extending sides.
7. An aerofoil arrangement (20) according to any preceding claim, characterized in that the support member (24) defines at least one bevel edge (4) defining a gap region (42, 44), wherein, in use, a leading or trailing edge region (26, 27) of an adjacent aerofoil (22) extends over the gap region (42, 44).
8. An aerofoil arrangement (20) according to claim 7, characterized in that the, or each, gap region (43, 44) of the support member (24) is defined at a respective non- supporting corner region (43A, 43B) of the support member (24).
9. An aerofoil arrangement (20) according to claim 7 or 8 characterized in that the support member (24) comprises at least one supporting corner region (29A, 29B) where the leading edge and/or the trailing edge (26, 27) of the aerofoil (22) extends beyond the respective side of the support member (24) and at least one non-supporting corner region (43A, 43B) adjacent the supporting corner region (29A, 29B) and the, or each gap region (42, 44) is defined at a non-supporting corner region (43A, 43B) adjacent the, or each, supporting corner region (29A, 29B) of the support member (24).
10. An aerofoil arrangement (10) according to claim 7 or 8 characterized by a pair of gap regions (42, 44) defined diagonally opposite each other.
11. An assembly comprising a plurality of aerofoil arrangements (20) as claimed in any preceding claim arranged in succession adjacent each other.
12. An assembly according to claim 11 when dependent upon any of claims 7 to 10 characterized in that a gap region (42, 44) is defined between adjacent aerofoil arrangements (20) and a leading edge and/or a trailing edge (26, 27) of one aerofoil arrangement (20) extends over the gap region (42,44) of the, or each, adjacent aerofoil arrangement (20).
13. A rotary component of a gas turbine engine incorporating an assembly as claimed in claim 11 or 12.
14. A stationary component of a gas turbine engine incorporating an assembly as claimed in Claim 11 or 12.
15. A gas turbine engine incorporating a rotary component as claimed in claim 13.
16. A gas turbine engine incorporating a stationary component as claimed in Claim 14.
17. An aerofoil arrangement substantially as herein described with reference to Figs. 2 to 4 of the drawings.
18. An aerofoil arrangement substantially as herein described with reference to Figs. 5 and 6 of the drawings.
19. Any novel subject matter or combination including novel subject matter disclosed herein, whether or not within the scope of or relating to the same invention as any of the preceding claims.