Combustor Dome Assembly

Abstract

An improved dome assembly for a gas turbine engine combustor includes fastening means to connect the dome plate to the combustor liners in such a manner as to provide a substantially uniform film coolant on the inside of the liner at the intersection of the dome plate and the liner. The fastening means are located entirely outside of the hot gas region of the combustor and permit disassembly of the liner, dome plate and a surrounding cowl or snout ring assembly.

Description

BACKGROUND OF THE INVENTION

This invention relates generally to gas turbine engine combustor assemblies and, more particularly, to improved mounting and cooling apparatus for a combustor dome assembly.

The invention herein described was made in the course of or under a contract, or a subcontract thereunder, with the U.S. Department of the Air Force.

In the combustion apparatus of gas turbine engines, the actual combustion occurs within a combustion zone or space defined by a pair of combustion liners or walls. The upstream end of the combustion zone is normally defined by a dome member which is connected to the combustion liners and which is adapted to provide openings for a plurality of fuel/air carbureting devices, which provide the combustion zone with a continuous flow of high energy fuel. In many cases, the dome member is surrounded by a snout assembly which is located immediately downstream of the compressor section of the engine and defines an inlet through which a major portion of the combustion air flows.

The combustion liners are normally of perforated construction to permit large quantities of air to flow therethrough into the combustion space to support the combustion process and to dilute the combustion products to provide a desired turbine temperature. Cool compressor air is supplied to the space surrounding the liners and to the inlet formed by the snout assembly.

To attain reasonably satisfactory performance and operating life, the combustion liners are provided with louvered joints or coolant holes constructed and arranged to extract relatively small quantities of air from the compressor airflow and to direct the extracted air into the combustion space such that it forms thin, insulating layers of coolant on the inner surface of the liner. These thin films not only protect the liner from direct contact with the high temperature gases, but also remove radiated heat through convective contact with the liner. Ideally, these films of cooling air provide sufficient, but not excessive, quantities of cooling air and substantially uniform protection. In practice, however, the flow pattern normally existing within the combustion space and other combustion variables make it virtually impossible to provide uniform protection, and certain thermal gradients and accompanying stresses are to be expected in all known prior art devices.

Even assuming that relatively constant temperature levels can be attained in individual combustor components, the expected life of such components will vary due to the various environments within which the components are situated. For example, even an effectively cooled combustion liner will not have the same life capabilities as the snout assembly, which is not exposed to the high combustor temperatures. In order to avoid the necessity of replacing an entire combustor assembly because of a localized failure or limited life component, it is therefore desirable that the liner assembly be fabricated such that the elements can be easily disassembled, the defective or used parts repaired or replaced, and the elements then reassembled into a complete combustor assembly.

As a result of these requirements, rivets or similar mechanical fastening means have been utilized to connect combustor components to one another. Experience has shown, however, that the use of such devices normally results in a less effectively cooled liner because the rivets or other fastening means are positioned within the coolant air passages and/or the hot gas stream and thus either interfere with the air-flow through the cooling joints, thereby causing wakes and non-uniformities in the cooling air film, or are directly exposed to the hot gas stream. This condition is especially prevalent in the joint between the dome member and the combustion liners, which joint lies at the upstream end of the combustion zone.

SUMMARY OF THE INVENTION

It is an object of this invention, therefore, to provide an improved combustor assembly in which a relatively uniform film of coolant can be applied to the liner panel immediately downstream of a joint formed between the combustor liner and the dome member forming the upstream end of the combustion zone. It is a further object of this invention to provide such an improved combustor assembly in which the various combustor components are readily disassembled and reassembled and in which the means connecting the various components together are located entirely outside of the hot gas stream.

Briefly stated, the above and similarly related objects are attained in the present instance by providing a combustor dome plate which includes a pair of embossed mounting rings which extend upstream from the dome plate and are adapted to be connected to a pair of combustor liners, which form the combustion zone, and to a pair of snout rings which form an inlet plenum upstream of the combustion zone. Each of the mounting rings includes a corrugated wiggle strip at its downstream end which cooperates with the dome plate to form a first plurality of coolant flow passages therebetween. In one embodiment, the mounting rings further include dimpled portions which cooperate with the snout rings to form a second plurality of cooling passages which are interspersed between each pair of the first plurality to form a relatively uniform circumferential film of cooling air at the joint between the dome plate and the combustor liner. Fastening means, which may take the form of a plurality of bolts and nuts, are positioned between each of the dimples and adapted to interconnect the snout ring, the liner, and the mounting ring. In another embodiment, the mounting ring forms an annular chamber which feeds the alternate cooling passageways formed by the wiggle strip. In either case, the fastening means are positioned within a cool air plenum located upstream of the combustion zone and are further positioned a sufficient distance upstream of the plurality of coolant passages so as to have little effect on the film of coolant emitted therefrom.

DESCRIPTION OF THE DRAWINGS

While the specification concludes with a series of claims which particularly point out and distinctly claim the subject matter which Applicants regard as their invention, a clear understanding of the invention will be obtained from the following detailed description, which is given in connection with the accompanying drawings, in which:

FIG. 1 is a partial, cross-sectional view of the combustion apparatus of a gas turbine engine, with the combustion apparatus including the improved film assembly joint construction of this invention;

FIG. 2 is an exploded view of portions of FIG. 1;

FIG. 3 is an enlarged, cross-sectional view, with portions deleted, taken generally through one of the dome fastening means of FIG. 1;

FIG. 4 is an enlarged, cross-sectional view, similar to FIG. 3, taken generally through a cooling air dimple;

FIG. 5 is an enlarged, cross-sectional view, with portions deleted, taken generally along line 5--5 of FIG. 3;

FIG. 6 is an enlarged, sectional view, with portions deleted, taken along line 6--6 of FIG. 3;

FIG. 7 is an exploded view, similar to FIG. 2, showing an alternative embodiment;

FIG. 8 is an enlarged, cross-sectional view, similar to FIG. 4, of the embodiment of FIG. 7;

FIG. 9 is an enlarged, cross-sectional view, similar to FIG. 3, of the embodiment of FIG. 7; and

FIG. 10 is an enlarged, sectional view, with portions deleted, taken along line 10--10 of FIG. 8.

DESCRIPTION OF A PREFERRED EMBODIMENT

Referring now to the drawings wherein like numerals correspond to like elements throughout, attention is directed initially to FIG. 1 wherein a portion of a gas turbine engine combustor assembly is illustrated in cross section and is generally designated by the numeral 10. The combustor assembly 10 includes an inner combustor casing 12 and an outer combustor casing 14 which cooperate to define an annular flow path downstream of a compressor, one stage of which is shown in the form of compressor outlet guide vanes 16.

A pair of combustor liners 18 and 20 are positioned between the inner casing 12 and the outer casing 14 in such a manner as to form a combustion zone 22. A turbine nozzle assembly 24 is positioned at the downstream end of the inner casing 12 and the outer casing 14. The turbine nozzle assembly 24 includes a pair of flanges 26 and 28 to which the downstream end of the combustor liners 18 and 20, respectively, are mounted. A combustor dome assembly 30 is mounted to the upstream end of the liners 18 and 20 in such a manner as to form the upstream end of the combustion zone 22.

As best shown in FIGS. 2 and 7, the combustor dome assembly includes a dome plate 32, which includes a plurality of truncated, conical sections 34 uniformly spaced therearound and adapted to provide a plurality of central openings 36 which receive fuel/air carbureting devices 38 (FIG. 1). The dome assembly 30 further includes inner and outer mounting rings 40 and 42, respectively, which extend from the downstream end of the dome plate 32.

As further shown in FIGS. 1, 2 and 7, the combustor assembly 10 also includes a pair of snout rings 44 and 46, which are adapted to mount to the combustor liners 18 and 20 and the inner and outer mounting rings 40 and 42 in a manner to be described. The snout rings 44 and 46 cooperate to define an annular inlet 48 downstream of the compressor outlet guide vanes 16, and the snout rings 44 and 46 cooperate with the dome assembly 30 to define an inlet plenum 50 at the upstream end of the combustion zone 22. As shown most clearly in FIGS. 2 - 5 the outer mounting ring 42 includes a plurality of dimples 52 which are uniformly spaced around the perimeter thereof and extend inwardly so as to form small chambers 54. The chambers 54 are fluidically connected to the inlet plenum 50 by means of an opening 56 located in each of the dimples 52. As further shown in FIGS. 2 - 4, that portion of the outer mounting ring 42 which is situated immediately downstream of each of the dimples 52 consists of a corrugated wiggle strip 58, which includes a plurality of outer flat sections 60 and a plurality of inner flat sections 62 formed at a slightly smaller diameter than that of the outer flat section 60 and interconnected by small angled rib members 61.

The outer mounting ring 42 further includes a plurality of holes 64 equally spaced around the perimeter of the ring and located between each of the dimples 52. As shown in FIG. 2, the holes 64 cooperate with a like number of holes 66 formed in the snout ring 44 so as to enable the snout ring 44 to be fastened to the outer mounting ring 42 by means of any suitable fastening device such as the bolts 68 and nuts 70.

As shown in FIGS. 2 - 4, the outer combustor liner 20 is connected to the snout ring 44 in any suitable manner, such as by weld bead 72, between the upstream end of the liner 20 and the downstream end of the ring 44. In this manner, the bolts 68 act to fasten the outer mounting ring 42 and, thus, the dome plate 32 to both the snout ring 44 and to the liner 20.

As further shown in FIGS. 2 - 4, the mounting ring 42 is connected to the dome plate 32 near the downstream end of the dome plate 32. For this reason, each of the inner flat sections 62 of the wiggle strip 58 is connected in any suitable manner, such as by brazing or welding, to a cylindrical lip 74 which forms the outer portion of the downstream end of the dome plate 32. When thus connected, and as best shown in FIGS. 3 and 6, the outer flat sections 60 of the wiggle strip 58 cooperate with the cylindrical lip 74 of the dome plate 32 to form a plurality of cooling passages 76 therebetween. Each of the cooling passages 76 lies in fluid flow communication with the inlet plenum 50, and the bolts 68 and nuts 70 are positioned a sufficient distance upstream from the inlet of the coolant passages 76, as shown in FIG. 3, so as to have little effect on the coolant flow therethrough.

When the combustion liner 20, the dome plate 32 and the snout ring 44 are assembled as shown in FIG. 4, each of the inner flat sections 62 of the wiggle strip 58 cooperates with the snout ring 44 and the liner 20 to form a coolant passage 78 downstream of each of the dimples 52. Coolant is delivered to each of the cooling passages 78 from the inlet plenum 50 through each of the openings 56 provided in the dimples 52.

As best shown in FIG. 6, each of the coolant passages 78 is surrounded by a pair of the coolant passages 76 such that the coolant passages 76 and 78 cooperate to provide an annular exit slot which is continuous except for the rib members 61, which are a part of the wiggle strip 58 and are located between each of the outer flat section 60 and the inner flat section 62. Since the rib members 61 can be made of extremely thin sheet metal, and since the rib members 61 can be angled with respect to both the dome plate 32 and the liner 20, the rib members 61 have little, if any, effect on a continuous film of coolant being emitted from the annular slot exit provided by the coolant passages 76 and 78. As shown in FIGS. 3 and 4, the annular slot exit formed by the coolant passages 76 and 78 is located immediately inside inner wall 82 of a first panel of the combustor liner 20. The coolant passages 76 and 78 thus act to provide a continuous film of coolant on the inner wall 82 of the first panel of the liner 20.

While the inner mounting ring 40 and the snout ring 46 could be made identical to the outer mounting ring 42 and outer snout ring 44, a suitable alternative design is shown in FIGS. 7 - 10 which will provide the same continuous film cooling for the upstream panel of the combustion liner. As shown in FIG. 7, the inner mounting ring 40 includes a forward end cylindrical ring 84, a conical intermediate portion 86 and a downstream embossed wiggle strip 88. The wiggle strip 88 is similar to the wiggle strip 58 in that it includes outer flat sections 90 and inner flat sections 92 which are interconnected to one another by a small angled rib member 94.

As further shown in FIG. 7, the outer flat sections 90 are connected to a downstream cylindrical portion 96 of the dome plate 32 in any suitable manner such as by welding. When thus connected, the inner flat portions 92 of the wiggle strip 88 cooperate with the cylindrical portion 96 of the dome plate 32 to form a plurality of coolant passages 98.

Referring still to FIG. 7, the upstream cylindrical portion 84 of the inner mounting ring 40 is provided with a plurality of equally spaced holes 100 which are adapted to cooperate with a like number of holes 102 located in the inner liner 18. The holes 100 and 102 are further adapted to align with holes 104 located in the snout ring 46 such that the snout ring 46, the liner 18, and the inner mounting ring 40 may be suitably interconnected by some suitable fastening means, such as the bolts 106 and nuts 108.

When the snout ring 46, the liner 18, and the mounting ring 40 are interconnected by means of the bolts 106, the liner 18 cooperates with the intermediate portion 86 of the mounting ring 40 to form a coolant chamber 110. The chamber 110 is fluidically connected to the inlet plenum 50 by means of a plurality of holes 112 (FIG. 8) located within the intermediate portion 86 of the mounting ring 40.

Furthermore, the liner 18 and the outer flat portions 90 of the wiggle strip 88 cooperate as shown in FIG. 9 to form a plurality of coolant passages 114, one of which is positioned between each pair of the coolant passages 98 as shown in FIG. 10. The coolant passage 78 communicates directly with inlet plenum 50, and the coolant passage 114 lies in fluid flow communication with the chamber 110 which is supplied with coolant through the holes 112 from inlet plenum 50. In this manner, the coolant passages 98 and 114 act to provide a continuous film of coolant on the inner side 116 of upstream panel of the inner combustor liner 18.

As described above, both the inner mounting ring 40 and the outer mounting ring 42 provide an assembly which yields a continuous film coolant on the inner side of an upstream panel of a combustor liner. The inner mounting ring 40 and the outer mounting ring 42 are distinguished by the fact that the outer mounting ring 42 includes the plurality of dimples 52, whereas the inner mounting ring 40 provides a continuous annular chamber 110. The outer mounting ring 42 may be more susceptible to use where it is desirable to have the fastening means, such as the bolts 68, located close to the joint between the dome plate and the combustion liner, whereas the inner mounting ring 40 may be more appropriate for use in situations where the fastening means can be located a greater distance away from the joint. Either case provides a continuous film of coolant on the upstream panel of the combustion liner and further provides a system wherein the fastening means are located entirely outside of the high temperature combustion zone. Furthermore, either of the above-described devices provides an assembly in which the fastening means are positioned a sufficient distance upstream of the cooling passages such that the fastening means will not cause wakes to appear in the coolant flow. In this manner, the need for wake reduction holes in the combustion liner is eliminated. The advantages of the above-described system are readily apparent to those skilled in the art.

While two alternative embodiments of applicants' improved dome assembly have been described above, it will be readily apparent to those skilled in the art that slight changes could be made in the above-described structure without departing from applicants' broad inventive concepts. It is intended, therefore, that the appended claims cover all such changes which do not depart from the broader inventive concepts described herein.

Claims

What is claimed is:

1. In a combustor assembly including a pair of combustor liners radially spaced from one another and adapted to form a combustion zone therebetween, a dome assembly adapted to be positioned between said liners and to cooperate therewith to form the upstream end of said combustion zone, and a pair of snout rings adapted to surround said dome assembly and to define an inlet plenum upstream of said combustion zone, the improvement comprising:

said dome assembly includes a dome plate having an upstream end, a downstream end, which forms a generally annular-shaped opening which lies in fluid flow communication with said combustion zone, and at least one mounting ring extending from said downstream end of said dome plate, said mounting ring includes means for removably connecting said dome plate to at least one of said liners, wherein said connecting means are characterized in that they are positioned completely outside of said combustion zone, and wherein said mounting ring includes means for delivering a coolant from said inlet plenum to the inner side of at least one of said liners as a substantially uniform circumferential film at the intersection of said dome assembly and said liner wherein said connecting means comprise a plurality of bolts at least a portion of which extend into said inlet plenum upstream of said coolant delivery means such that said bolts do not interfer with said coolant film, and said mounting ring includes a wiggle strip connected to said dome plate in such a manner as to surround said dome plate at said intersection of said dome assembly and said liner.

2. The improved combustor assembly recited in claim 1 wherein said connecting means also connect one of said snout rings to said liner and at least a portion of said snout ring surrounds said mounting ring.

3. The improved combustor assembly recited in claim 1 wherein said mounting ring includes a plurality of uniformly spaced dimples and said dimples act to provide a first plurality of coolant passages between said liner and said mounting ring.

4. The improved combustor assembly recited in claim 3 wherein said connecting means are positioned between each pair of said dimples, and said mounting ring and said dome plate are spaced from one another downstream of each of said connecting means so as to form a second plurality of coolant flow paths therebetween, one of said second plurality being spaced between each pair of said first plurality.

5. The improved combustor assembly recited in claim 4 wherein said dome assembly includes a second mounting ring located at the downstream end of said dome member, said second mounting ring includes means for connecting said second liner thereto, and said second mounting ring includes means for delivering a coolant from said inlet plenum to the inner side of said second liner as a substantially uniform circumferential film at the intersection of said dome member and said second liner.

6. The improved combustor assembly recited in claim 5 wherein said second mounting ring cooperates with said second liner to define an annular chamber therebetween, and said second mounting ring includes a wiggle strip adapted to provide a first plurality of coolant passages between said second liner and said second mounting ring.

7. The improved combustor assembly recited in claim 6 wherein said wiggle strip further provides a second plurality of coolant passages formed between said second mounting ring and said downstream end of said dome plate, with one of said second plurality lying between each pair of said first plurality.

8. The improved combustor assembly recited in claim 7 wherein said first connecting and said second connecting means comprises a plurality of bolts and nuts and said nuts are mounted to the inner side of said first and second mounting rings.