GB1578474A

GB1578474A - Combustor mounting arrangement

Info

Publication number: GB1578474A
Application number: GB955377A
Authority: GB
Original assignee: General Electric Co
Current assignee: General Electric Co
Priority date: 1976-06-21
Filing date: 1977-03-07
Publication date: 1980-11-05
Also published as: FR2356000A1; DE2711564A1; JPS52156213A

Description

(54) IMPROVEMENTS IN COMBUSTOR MOUNTING ARRANGEMENT (71) We, GENERAL ELECTRIC COM- PANY, a Corporation organised and existing under the laws of the State of New York, United States of America, residing at 1, River Road, Schenectady, 12305, State of New York, United States of America, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement : This invention relates generally to gas turbine engines and, more particularly, to the mounting of an air-cooled combustor therein.

Increased performance levels of gas turbine engines can be obtained by increasing the operating temperatures thereof. In so doing, combustion chambers of these gas turbine engines are exposed to extremely high temperatures which would be destructive to the combustor apparatus unless some precautions are taken. Although there have been great improvements in liner alloys and other combustion chamber materials in order to allow higher temperature operation, a common method of enhancing combustion chamber life and dependability is to cool the combustion chamber by way of cooling air circulation. This is typically accomplished in an annular combustor by the circumscribing of the combustor liner with an annular combustor casing, to thereby define an annular plenum into which air is delivered under high pressure from the engine compressor.

Most of this air in the cooling plenum is routed through a plurality of holes or slots in the liner walls where it tends to form a protective film barrier on the inner wall surface by a phenomenon known as film- surface cooling wherein a thin layer of cooling air is formed between the combustor liner and the hot gases of combustion contained therein. However, a portion of the cooling air in the plenum is passed further downstream where it is used for turbine stator and/or shroud cooling. Since the stator cooling methods employed include the impingement cooling concept, wherein air is made to flow through small holes and impinge with high velocity on the element to be cooled, it is important that such cooling air be relatively free of solid particles so as not to plug the impingement openings.

Support of a combustor liner has typically been provided by some support means attached either to the upstream end or the downstream end or both of the combustor liner, and a typical approach has been to attach the liner to the outer casing by some type of bracket. However, it will be recog- nized that, since the combustor liner is exposed to very high temperature gradients from the combustion gases inside, and since the outer casing is maintained at relatively cool temperatures, the relative thermal growth between the supporting casing and the supported liner must be accommodated by way of a flexible coupling.This thermal flexibility must, of course, be provided in the radial direction, but to complicate matters further the axial position of the combustor liner must necessarily remain substantially stable so as to maintain the proper interface with both the fuel injectors on the upstream end thereof and with the turbine nozzle on the downstream end thereof.

It is therefore an object of this invention to provide in a combustor liner support, means to allow for relative radial thermal growth while at the same time providing for a substantially stable axial position thereof.

According to the present invention there is provided an improved turbomachinery combustor arrangement of the type having in serial flow relationship a compressor, and a turbine, the combustor being supported by an adjacent supporting structure which is adapted for exposure to substantially cooler temperatures than the combustor during operating conditions, wherein the improvement comprises a support member rigidly connecting said combustor to said supporting structure, said support member comprising a first leg connected to the support structure and a second leg connected to the support structure and a second leg connected to the combustor, the legs being at an acute angle to each other to provide flexibility for accommodating relative thermal expansion between said combustor and said supporting structure.

The invention will now be described in greater detail by way of example with reference to the accompanying drawings wherein: Figure 1 is an axial cross-sectional view of an exemplary gas turbine combustion apparatus embodying the present invention.

Figure 2 is an enlarged partial crosssectional view thereof showing the inner bracket portion thereof.

Figure 3 is an enlarged partial crosssectional view thereof showing the outer bracket portion thereof.

Figure 4 is a fragmented axial view of the inner bracket portion thereof as seen along line 4-4 of Figure 2, with portions broken away therefrom to better show its detailed structure.

Figure 5 shows a sectional view of the bracket as seen along line 5-5 of Figure 2.

Referring now to the drawings, and particularly Figure 1, the invention is shown generally at 10 as applied to a combustion apparatus 11 of the type suitable for use in a gas turbine engine and comprising a hollow body 12 defining the combustion chamber 13 therein. The hollow body 12 is generally annular in form and is comprised of an outer liner 14, an inner liner 16 and a domed end 17. It should be understood, however, that this invention is not limited to such an annular configuration but may be employed with equal effectiveness in combustion-type apparatus of the well-known cylindrical can, or cannular type or other coannular shell structures which require relatively rigid axial positioning of a radial plane while allowing essentially axisymmetric relative radial thermal growth.In the present annular configuration, the domed end 17 of the hollow body 12 is formed with a plurality of circumferentially spaced openings 18, each having disposed therein a fuel injection apparatus 19 for the delivery of fuel/air mixture into the combustion chamber 13.

The hollow body 12 is enclosed between outer and inner compressor casings, 21 and 22, which together with liners 14 and 16 define outer and inner cooling plenums 23 and 24, respectively, which are adapted to deliver a flow of pressurized air from a suitable source such as a compressor 25 and diffuser 26, into the combustion chamber 13 by way of suitable apertures or louvers 27 for cooling of the hollow body 12 and dilution of the gaseous products of combustion in a manner well known in the art. The upstream extension 28 of the hollow body 12 is adapted to function as a flow splitter, dividing the pressurized air delivered from the compressor 25, between the combustor dome openings 18 and the cooling air plenums 23 and 24.While the opening 18 fluidly communicates with the fuel injection apparatus 19 to provide the required air for carburetion, most of the air goes further into the cooling air plenums 23 and 24 to enter the combustor liner through the apertures 27 for purposes of cooling the inner side thereof. A portion of the air continues further downstream along the plenums 23 and 24 as indicated by the arrows to cool the turbine nozzle 29 and turbine blades 30 in a manner well known in the art.

As can be seen in Figure 1, structural support is provided to the combustor hollow body 12, at its downstream end, by outer and inner annular brackets 31 and 32 which are attached to the outer and inner casings 21 and 22, respectively, by appropriate fastening means such as by entrapping, bolting or the like. The outer and inner brackets 31 and 32 are each formed at angles so as to provide for thermal growth flexibility between the hot, hollow body structure 12 and the relatively cool supporting casing structure. The brackets 31 and 32 also include, as a part thereof, a screening material which tends to filter out any of the solid impurities which are in the air as it flows from the plenum 23 and 24 into the cooling chambers 33 and 34, respectively.The particular detailed structure of the brackets 31 and 32 can be more clearly seen by reference to Figures 2-5.

Referring now to Figures 2, 4 and 5, the inner bracket 32 is shown to include a support element 36 with first and second legs 42 and 48, respectively, arranged at an acute angle to each other. The end 37 of the leg 42 is rigidly attached to the inner liner 16 by way of a suitable method such as by welding. At the end of the leg 48, a flange 38 extends radially inward and is connected to the inner casing structure 22 by way of a plurality of bolts 39 extending through suitable openings 41 in the support element 36. The leg 48 extends generally axially of the engine.

The angled leg 42 of the support element 36 comprises an outer continuous annular ring 43 having circumferentially spaced, radially inward extending ribs 44 which terminate in an angled ring 46. The outer ring 43, the ribs 44, and the angled ring 46 define a plurality of circumferentially spaced openings 47 (Figure 4) through which the cooling air may pass as it goes from the plenum 24 into the chamber 34. The axial leg 48 of the support element 36 is constructed in a similar manner so as to also allow the flow of air into the chamber 34.

In order to prevent the flow of contaminants through the openings 47, which contaminants may tend to cause a plugging of the cooling holes in the turbine nozzles 29, an arcuate screen 49 is placed over the angled leg 42 so as to cover all the openings 47 and provide a filter therefor. Similarly, an arcuate screen 51 is placed over the axial leg 48 for the same purpose. The screens 49 and 51 are held in place by an angled cover 52 which includes a central portion 53 and radially extending legs 54 whose circumferential location corresponds to the ribs 44 therebeneath. The angled cover 52 may be segmented as shown or may just as well be composed of a single integral element.Also corresponding are the holes 56, 57 and 58 (Figure 4) in the outer ring 43, the screen 49 and the legs 54, respectively, into which are placed fastening devices 59 such as rivets or the like so as to form a rigid assembly. Similarly, on the axial side of the cover 52 are a plurality of legs 61 which act to cover portions of the screen 51 and which are held in place by fastening devices 62. An angled ring 63 may in turn be placed over the axial legs 61 and also be secured by the rivets 62 for the purpose of axial retention of the attachment bolts 39.

Although not shown in Figures 1 and 2, the present invention contemplates the use of some type of seal between the bracket outer ring 43 and the turbine nozzle structure 64 (Figure 2). The particular type of seal 'employed is not important to the present invention, and for purposes of description can be thought of as a simple leaf seal.

Referring now to Figure 3, the outer bracket 31 is shown and, except for the fact that this bracket assembly is shaped at a smaller included angle than that of the bracket assembly 32, the structure is essentially identical. The angled support element 65 is covered with screens 66 and 67, and an angled cover 68 is fastened in place by rivets 69 and 71 to form the combination support and filter element. It will be seen that the outer end of the bracket 72 is rigidly connected to the supporting ring 73 which in turn is positioned axially and circumferentially to the outer casing 21 by a suitable means. The inner end of the bracket is connected to the combustor outer liner 14 by suitable means such as welding.Again, although not shown, in Figure 3, a sealing arrangement would preferably be placed between the outer liner 14 and the turbine nozzle structure 64 so as to prevent the leakage of cooling air out into the hot gas of the main flow stream.

It is contemplated that the invention as described will provide the entire support for the combustor hollow body 12 with the angled support brackets 31 and 32 allowing for the relative growth of the hollow body 12 within the combustor casing, while at the same time maintaining a stable axial position therein. In addition to providing support, the screen-covered brackets also provide for the filtering of all of the cooling air which passes to the turbine vane structure to thereby prevent the entrance of contaminants into the cooling holes.

It will be understood that modifications may be made to the construction described above. For example, it will be recognized that the particular angle of the brackets may be varied from those shown. Further, the bracket configuration should not be necessarily limited to a two-legged bracket, but may comprise a plurality of angled legs, some or all of which may have a screening material applied thereto. Yet another approach may be to fasten the filter screens directly to the angled support member without the use of the angled cover element as shown in the preferred embodiment. It will therefore be apparent that deviations from the preferred embodiment described will occur to those skilled in the art. The appended claims are thus intended to cover any modifications similar to those described above which fall within the broader aspects of Applicants' invention.

WHAT WE CLAIM IS:- 1. An improved turbomachinery combustor arrangement of the type having in serial flow relationship a compressor, a combustor and a turbine, the combustor being supported by an adjacent supporting structure which is adapted for exposure to substantially cooler temperatures than the combustor during operating conditions, wherein the improvement comprises a support member rigidly connecting said combustor to said supporting structures, said support member comprising a first leg connected to the support structure and a second leg connected to the combustor, the legs being at an acute angle to each other to provide flexibility for accommodating relative thermal expansion between said combustor and said supporting structure.

2. An improved turbomachinery combustor arrangement as set forth in claim 1 wherein said support member is connected to the downstream end of said combustor.

3. An improved turbomachinery combustor arrangement as set forth in claim 1 wherein said supporting structure comprises a combustor outer casing.

4. An improved turbomachinery combustor arrangement as set forth in claim 1 wherein said combustor is of the annular type and said supporting structure comprises a combustor outer casing.

5. An improved turbomachinery combustor arrangement as set forth in claim 4 and including a second angled support member interconnecting said combustor to a combustor inner casing.

6. An improved turbomachinery com

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. the cooling holes in the turbine nozzles 29, an arcuate screen 49 is placed over the angled leg 42 so as to cover all the openings 47 and provide a filter therefor. Similarly, an arcuate screen 51 is placed over the axial leg 48 for the same purpose. The screens 49 and 51 are held in place by an angled cover 52 which includes a central portion 53 and radially extending legs 54 whose circumferential location corresponds to the ribs 44 therebeneath. The angled cover 52 may be segmented as shown or may just as well be composed of a single integral element. Also corresponding are the holes 56, 57 and 58 (Figure 4) in the outer ring 43, the screen 49 and the legs 54, respectively, into which are placed fastening devices 59 such as rivets or the like so as to form a rigid assembly.Similarly, on the axial side of the cover 52 are a plurality of legs 61 which act to cover portions of the screen 51 and which are held in place by fastening devices 62. An angled ring 63 may in turn be placed over the axial legs 61 and also be secured by the rivets 62 for the purpose of axial retention of the attachment bolts 39. Although not shown in Figures 1 and 2, the present invention contemplates the use of some type of seal between the bracket outer ring 43 and the turbine nozzle structure 64 (Figure 2). The particular type of seal 'employed is not important to the present invention, and for purposes of description can be thought of as a simple leaf seal. Referring now to Figure 3, the outer bracket 31 is shown and, except for the fact that this bracket assembly is shaped at a smaller included angle than that of the bracket assembly 32, the structure is essentially identical. The angled support element 65 is covered with screens 66 and 67, and an angled cover 68 is fastened in place by rivets 69 and 71 to form the combination support and filter element. It will be seen that the outer end of the bracket 72 is rigidly connected to the supporting ring 73 which in turn is positioned axially and circumferentially to the outer casing 21 by a suitable means. The inner end of the bracket is connected to the combustor outer liner 14 by suitable means such as welding.Again, although not shown, in Figure 3, a sealing arrangement would preferably be placed between the outer liner 14 and the turbine nozzle structure 64 so as to prevent the leakage of cooling air out into the hot gas of the main flow stream. It is contemplated that the invention as described will provide the entire support for the combustor hollow body 12 with the angled support brackets 31 and 32 allowing for the relative growth of the hollow body 12 within the combustor casing, while at the same time maintaining a stable axial position therein. In addition to providing support, the screen-covered brackets also provide for the filtering of all of the cooling air which passes to the turbine vane structure to thereby prevent the entrance of contaminants into the cooling holes. It will be understood that modifications may be made to the construction described above. For example, it will be recognized that the particular angle of the brackets may be varied from those shown. Further, the bracket configuration should not be necessarily limited to a two-legged bracket, but may comprise a plurality of angled legs, some or all of which may have a screening material applied thereto. Yet another approach may be to fasten the filter screens directly to the angled support member without the use of the angled cover element as shown in the preferred embodiment. It will therefore be apparent that deviations from the preferred embodiment described will occur to those skilled in the art. The appended claims are thus intended to cover any modifications similar to those described above which fall within the broader aspects of Applicants' invention. WHAT WE CLAIM IS:-

1. An improved turbomachinery combustor arrangement of the type having in serial flow relationship a compressor, a combustor and a turbine, the combustor being supported by an adjacent supporting structure which is adapted for exposure to substantially cooler temperatures than the combustor during operating conditions, wherein the improvement comprises a support member rigidly connecting said combustor to said supporting structures, said support member comprising a first leg connected to the support structure and a second leg connected to the combustor, the legs being at an acute angle to each other to provide flexibility for accommodating relative thermal expansion between said combustor and said supporting structure.

6. An improved turbomachinery com

bustor arrangement as set forth in claim 1 wherein said support member is formed with a plurality of holes therein so as to provide for the flow of air therethrough.

7. An improved turbomachinery combustor arrangement as set forth in claim 6 wherein said holes are of a substantial size and further including at least one screen structure attached to said support member to filter out impurities that would otherwise pass through said holes.

8. An improved turbomachinery combustor arrangement as set forth in claim 1 wherein the combustor has an inner liner and an outer casing to mutually define a flow path for cooling air, a portion of which passes through openings in the combustor liner to provide cooling to the inner surface thereof and a portion of which continues to along the flow path to the turbine stator, a screening element being disposed in said flow path for allowing air to flow therethrough while filtering out any solid contaminants that may otherwise flow to the turbine stator.

9. An improved turbomachinery combustor arrangement as set forth in claim 8 wherein said screening element is interconnected between said inner liner and outer casing.

10. An improved turbomachinery combustor arrangement as set forth in claim 8 wherein said combustor is supported by a support structure interconnected between said combustor liner and said outer casing and further wherein said screening element is attached to said support structure.

11. A combustor arrangement substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.~~ ~ ~ ~ ~ ~~