BACKGROUND
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The invention relates to combustor liners, and more specifically to combustor band louvers that provide cooling as well as promote beneficial flow characteristics within the combustor.
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Gas turbine engine combustors utilize cooling holes to thermally protect combustor liners from the heat of combustion. In some instances, band louvers are used to direct cooling air along the liner wall in the upstream direction and the downstream direction relative to a flow through the combustor. While prior band louver designs are considered suitable for their intended purpose, improved cooling and/or improved louver construction is highly desirable.
SUMMARY
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According to one aspect of the present invention, there is provided a louver segment including an arcuate member and a rib. The arcuate member extends circumferentially partially about an axis from a first side to a second side and extends axially parallel to the axis from an upstream end to a downstream end. The arcuate member includes an inner surface facing radially inward relative to axis and an outer surface facing radially outward relative to the axis. The rib extends circumferentially along the outer surface between the first and the second side.
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According to another aspect of the present invention, there is provided a combustor including an inner wall, an outer wall, and a plurality of louver segments. Each of inner wall and the outer wall circumscribe an axis to define an annular combustion chamber. The plurality of louver segments is supported from one of the inner wall and the outer wall and circumscribes the axis. Each louver segment of the plurality of louver segments includes an arcuate member and a rib. The arcuate member extends circumferentially partially about the axis from a first side to a second side and extends axially parallel to the axis from an upstream end to a downstream end. The arcuate member includes an inner surface facing radially inward relative to axis and an outer surface facing radially outward relative to the axis. The rib extends circumferentially along the outer surface between the first and the second side.
BRIEF DESCRIPTION OF THE DRAWINGS
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- FIG. 1 is an axial cross-section through an example gas turbine engine.
- FIG. 2 is an axial cross-section through a combustor of the example gas turbine engine.
- FIG. 3 is a partial developed view depicting a wall of a combustor configured for a louver segment.
- FIG. 4 is an isometric view of an example louver segment.
- FIG. 5 is another isometric view of the louver segment depicting features of a side rail of the louver segment.
DETAILED DESCRIPTION
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As described herein, a louver segment forms a portion of a gas turbine engine combustor for delivering cooling fluid along surfaces of the combustion chamber. Multiple louver segments assembled as a circumferentially extending band circumscribe an axis of the combustor and redirect cooling fluid delivered through the combustor wall along surfaces of the combustor in upstream and/or downstream directions. Louver segments further ease inspection and/or replacement of some or all of the louver band during regular maintenance intervals of the gas turbine engine.
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FIG. 1 is an axial cross-section through an example gas turbine engine 10 that can be equipped with a combustor with one or more louver segments described herein. While gas turbine engine 10 is depicted as a turbofan engine, the louver segments can be incorporated into combustors of other types of gas turbine engines. In some examples, gas turbine engine 10 can be a turboshaft engine or a turboprop engine suitable for propulsion of an aircraft and/or providing power to an auxiliary system of the aircraft (e.g., an auxiliary power unit). In other examples, gas turbine engine 10 can be a ground-based industrial gas turbine engine or an aeroderivative gas turbine engine. Further, gas turbine engine 10 can include fewer or more compressor stages and/or turbine stages than the number of stages depicted by FIG.1 and said stages can be configured as axial compressors and/or turbines, or centrifugal compressors and/or turbines arranged to form fewer or more shaft spools than the configuration depicted in FIG. 1.
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As depicted in FIG. 1, gas turbine engine 10 includes inlet 12, fan 14, fan case 16, bypass duct 18, low-pressure axial compressor 20, high-pressure centrifugal compressor 22, diffuser 24, plenum 26, combustor 28, fuel tubes 30, nozzle guide vane 32, turbines 34, and exhaust nozzle 36. Air intake into gas turbine engine 10 through inlet 12 passes over fan 14 in fan case 16 and is then split into an outer annular flow through the bypass duct 18 and an inner flow through the low-pressure axial compressor 20 and high-pressure centrifugal compressor 22. Compressed air exits high-pressure centrifugal compressor 22 through diffuser 24 and is contained within plenum 26 that surrounds combustor 28. Fuel supplied to combustor 28 through fuel tubes 30 mixes with air supplied from plenum 26 when sprayed through nozzles into combustor 28 as a fuel air mixture and is ignited. A portion of the compressed air within plenum 26 is admitted into combustor 28 through orifices in the side walls to create a cooling air film along the combustor walls or is used for cooling, which eventually mixes with the hot gases from combustor 28 and passes over nozzle guide vane 32 and turbines 34 before exiting nozzle 36 as exhaust. It will be understood that the foregoing description is intended to be exemplary of only one of many possible configurations of engine suitable for incorporation of the present invention.
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FIG. 2 is an axial cross-section of combustor 28 with inner wall 38, outer wall 40, head wall 42 (collectively liner walls), and louver segments 44. Inner wall 38 is spaced radially inward from outer wall 40 relative to centerline axis C to form annular combustion chamber 46. Head wall 42 extends from inner wall 38 to outer wall 40 to enclose an upstream end of combustor 28. Fuel tube 30 communicates with combustion chamber 46 via a port extending through head wall 42, however, the fuel nozzle arrangement is not shown, for simplicity. An ignitor extends through a port of outer wall 40 and is positioned in relation to one or more fuel tubes 30 to initiate combustion within combustion chamber 46.
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Louver segment 44 attaches to outer wall 40 and is spaced downstream from ignitor port 48 and head wall 42. Examples of combustor 28 can include louver segment 44 disposed between a primary combustor zone into which fuel is injected and a downstream zone into which additional air is injected for mixing with fuel for combustion as shown in FIG. 2. Louver segment 44 communicates with openings in outer wall 40 that place louver segment 44 in fluid communication with plenum 26 for distributing air along outer wall 40 in an upstream direction (i.e., towards head wall 42) and in a downstream direction (i.e., towards turbine 34).
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FIG. 3 is a developed view of combustor 28 taken along line B-B in FIG. 2 showing a portion of outer wall 40 with an envelope of louver segment 44 represented by dashed lines 50. Flow within combustor 28 generally flows a from primary combustor region towards turbine 34 as represented by arrow F.
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Outer wall 40 includes effusion holes 52, clearances holes 54, and one or more openings 56. Effusion holes 52 extend through outer wall 40 to fluidly connect plenum 26 to combustion chamber 46 and provide cooling along an interior surface of outer wall 40. Effusion holes 52 can be arranged in any pattern, group, and/or configuration suitable to achieve a target mass flow of effusion cooling along the interior surface of outer wall 40. Clearances holes 54 are positioned to receive one or more mechanical attachments for louver segment 44 and facilitate attachment of louver segment 44 to outer wall 40 and/or other structure outboard of combustor 28. Openings 56 extend through outer wall 40 to fluidly connect plenum 26 to a region between louver segment 44 and outer wall 40. Further, outer wall 40 and/or inner wall 38 can include one or more dilution holes 57 to achieve a desired fuel-to-air mixture within combustion chamber 46.
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FIG. 4 is an isometric view of louver segment 44 that can be attached to outer wall 40 of combustor 28. FIG. 5 is an isometric view of the example louver segment 44 that depicts the side of louver segment 44 in greater detail. FIG. 4 and FIG. 5 are discussed concurrently below.
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Louver segment 44 includes arcuate member 58 and studs 60 integrally formed with arcuate member 58. Arcuate member 58 extends circumferentially about axis C of combustor 28 from first side 62A to second side 62B and axially parallel to axis C from upstream end 64A to downstream end 64B, which coincide with upstream and downstream directions relative to flow F within combustor 28. That is to say, upstream end 64A faces upstream towards head wall 42 of combustor while downstream end 64B faces downstream towards turbine 34. Arcuate member 58 is curved and subtends a sector of combustor 28 between first side 62A and second side 62B. The included angle of the sector can greater than or equal to ten degrees and less than or equal to one hundred eighty degrees, or any other suitable sector. Arcuate member 58 is bound radially by inner surface 66 and outer surface 68. Inner surface 66 faces inward towards axis C of combustor 28 and is exposed to high temperature and pressure of combustion during operation of combustor 28. Outer surface 68 faces outward towards outer wall 40 (i.e., away from axis C).
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Arcuate member 58 conforms to a profile of outer wall 40 and is curved in at least a circumferential direction. In some examples, arcuate member 58 extends linearly in an axial direction parallel to axis C to conform to a cylindrical or a frustoconical portion of outer wall 40. In other examples, arcuate member 58 can be curved or contoured in the circumferential direction and the axial direction to conform to similar profiles of outer wall 40. That is to say, arcuate member 58 can be concave and/or convex along an axial direction parallel to axis C. In yet another example, arcuate member 58 can have a bend along the axial direction to conform to a joint of outer wall 40. As depicted in FIG. 2, FIG. 3, and FIG. 4, arcuate member 58 includes an upstream flange 70 conforming to a cylindrical portion of outer wall 40 and a downstream flange 72 conforming to a frustoconical portion of outer wall 40 that converges towards axis C in a downstream direction relative to combustor flow F.
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Arcuate member 58 includes rib 74 extending circumferentially along outer surface 68 of arcuate member 58 to increase radially stiffness of louver segment 44. Rib 74 extends radially to contact an interior surface of outer wall 40 and thereby spaces arcuate member 58 from outer wall 40. Rib 74 is disposed between upstream end 64A and downstream end 64B of arcuate member 58. In some examples, rib 74 divides arcuate member 58 into an upstream portion and a downstream portion as depicted in FIG. 4. In other examples, rib 74 can be disposed at or near upstream end 64A of arcuate member 58, at or near downstream end 64B of arcuate member, or any intermediate location between upstream end 64A and downstream end 64B. Depending on location, rib 74 can direct flow delivered via openings 56 to the region between arcuate member 58 and outer wall 40 in an upstream direction and/or a downstream direction to be discharge along outer wall 40. Intermediate locations of rib 74 (i.e., locations between upstream end 64A and downstream end 64B) form a T-shaped cross-section of louver segment 44 when viewed in a cross-sectional plane that includes axis C.
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Assembled within combustor 28, multiple louver segments 44 collectively define a louver band that circumscribes axis C of combustor 28 in conformity with outer wall 40. In some examples, circumferentially adjacent first and second sides 62A-62B of each arcuate member 58 abut such that louver segments 44 form a circumferentially continuous band in a cold state and/or a hot state of combustor 28. In other examples, circumferentially adjacent first and second sides 62A-62B define gaps between louver segments 44 as represented by dashed lines 76 in FIG. 4. Arcuate member 58 can be dimensionally configured such that louver segments 44 form gaps in the cold state, which remain during operation of combustor 28 in the hot state. In other examples, arcuate member 58 can be dimensionally configured such that gaps reduce as combustor 28 approaches the hot state.
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Examples of louver segments 44 configured to include gaps can additionally include one or more side rails 78. Side rails 78 extend axially, at least partially, between upstream end 64A to downstream end 64B of arcuate member 58. In certain examples, side rails 78 extend parallel to axis C to form gaps with circumferentially adjacent rails 78 or sides of arcuate member 58. Side rails 78 redirect circumferential cooling fluid flow along outer surface 68 of arcuate member 58 towards the upstream end 64A and/or towards the downstream end 64B to promote cooling fluid flow along outer wall 40 in the upstream and downstream directions respectively.
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Further examples of louver segment 44 can include one or more side apertures 80 extending through side rails 78 to fluidly connect the region between louver segment 44 and outer wall 40 with gaps. During operation of combustor 28, cooling fluid flowing through side apertures 80 purge high temperature combustion products from gaps as well as provide cooling to sides 62A-62B (or rails 78) of arcuate member 58. As depicted in FIG. 5, side apertures include upstream side apertures 80 and downstream side apertures 80, which fluidly connect the upstream and downstream regions of louver segment 44 to gaps respectively. As shown, side apertures 80 include two upstream side apertures 80 and three downstream side apertures 80. However, other examples of louver segment 44 can include fewer or more side apertures 80 than the configuration shown in FIG. 5.
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Louver segment 44 mechanically attaches to outer wall 40 via studs 60, which protrude from outer surface 68 of arcuate member 58 towards outer wall 40 and are configured to align with clearances holes 54 in outer wall 40. As shown, louver segment 44 includes three studs, which are approximately evenly spaced in a circumferential direction and extend from an upstream region of louver segment between rib 74 and upstream end 64A. Other examples of louver segment can include fewer or more studs 60 than the depicted example and may or may not be evenly spaced and/or positioned within the upstream region of louver segment 44. In other examples, one or more studs 60 can extend from the downstream region of louver segment 44 between rib 74 and downstream end 64B. Further, some examples of louver segment 44 can include unequal spacing between three or more studs 60 such that louver segment 44 can be assembled with outer wall 40 in a particular location only and/or with a particular orientation only. In each instance, studs 60 mechanically attach louver segment 44 to outer wall 40, or other stationary structure outboard of combustor 28. In the depicted examples, studs 60 are threaded such that nuts can be used to secure louver segment 44 to outer wall 40.
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Louver segment 44 can be manufactured to produce a monolithic body formed by at least arcuate member 58, rib 74, and studs 60. Examples of louver segment 44 that include one or more side rails 78 can form a monolithic body formed by arcuate member 58, rib 74, studs 60, and side rails 78. In certain examples of louver segment 44, a casting process forms the monolithic body after which subtractive manufacturing processes produce the finished geometry of louver segment 44 as described herein. Louver segment 44 can be coated to provide thermal protection and/or environmental protection. For example, inward-facing surfaces of louver segment 44 (e.g., inner surface 66 of accurate member 44, gap-facing side rail surfaces, upstream end 64A, and downstream end 64B) can include a thermal barrier coating while outward-facing surface of louver segment 44 (e.g., outer surface 68 of arcuate member 58, studs 60, and rib 74) can be coated with an environmental coating for corrosion resistance.
Discussion of Possible Embodiments
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The following are non-exclusive descriptions of possible embodiments of the present invention.
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A louver segment for a combustor of a gas turbine engine
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According to one aspect of the present invention, there is provided a louver segment including, among other possible things, an arcuate member and a rib. The arcuate member extends circumferentially partially about an axis from a first side to a second side and extends axially parallel to the axis from an upstream end to a downstream end. The arcuate member includes an inner surface facing radially inward relative to axis and an outer surface facing radially outward relative to the axis. The rib extends circumferentially along the outer surface between the first and the second side.
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The louver segment of the preceding paragraph can optionally include, additionally and/or alternatively, any one or more of the following features, configurations and/or additional components.
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Optionally, and in accordance with the above, the louver segment further can further include a first side rail extending axially along the first side of the arcuate member.
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Optionally, and in accordance with any of the above, the louver segment can further include a second side rail extending axially along the second side of the arcuate member.
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Optionally, and in accordance with any of the above, the louver segment can further include an effusion hole extending through the first side rail.
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Optionally, and in accordance with any of the above, the louver segment can further include an effusion hole extending through the second side rail.
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Optionally, and in accordance with any of the above, the louver segment can further include a plurality of studs extending outward from the outer surface of the arcuate member relative to the axis.
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Optionally, and in accordance with any of the above, the plurality of studs can be integrally formed with the arcuate member.
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Optionally, and in accordance with any of the above, at least a first stud of the plurality of studs can be disposed between the upstream end of the arcuate member and the rib.
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Optionally, and in accordance with any of the above, at least a second stud of the plurality of studs can be disposed between the downstream end of the arcuate member and the rib.
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Optionally, and in accordance with any of the above, the louver segment can be cast.
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Optionally, and in accordance with any of the above, the arcuate member and the rib can form a T-shaped cross-section in a cross-section taken along the axis.
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A combustor for a gas turbine engine
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According to another aspect of the present invention, there is provided a combustor for a gas turbine engine including, among other possible things, an inner wall, an outer wall, and a plurality of louver segments. Each of inner wall and the outer wall circumscribe an axis to define an annular combustion chamber. The plurality of louver segments is supported from one of the inner wall and the outer wall and circumscribe the axis. Each louver segment of the plurality of louver segments includes an arcuate member and a rib. The arcuate member extends circumferentially partially about the axis from a first side to a second side and extends axially parallel to the axis from an upstream end to a downstream end. The arcuate member includes an inner surface facing radially inward relative to axis and an outer surface facing radially outward relative to the axis. The rib extends circumferentially along the outer surface between the first and the second side.
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The combustor of the preceding paragraph can optionally include, additionally and/or alternatively, any one or more of the following features, configurations and/or additional components.
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Optionally, and in accordance with the above, the plurality of louver segments can form gaps between circumferentially adjacent sides of respective louver segments.
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Optionally, and in accordance with any of the above, each louver segment of the plurality of louver segments can further include a first side rail extending axially along the first side of the arcuate member.
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Optionally, and in accordance with any of the above, each louver segment of the plurality of louver segments can further include a second side rail extending axially along the second side of the arcuate member.
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Optionally, and in accordance with any of the above, circumferentially adjacent pairs of the first side rails and the second side rails of the plurality of louver segments can bound respective gaps between the louver segments.
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Optionally, and in accordance with any of the above, each louver segment of the plurality of louver segments can further include a side aperture extending through the first side rail or the second side rail.
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Optionally, and in accordance with any of the above, each louver segment of the plurality of louver segments can further include a plurality of studs extending outward from the outer surface of the arcuate member relative to the axis.
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Optionally, and in accordance with any of the above, the plurality of studs can be integrally formed with the arcuate member.
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Optionally, and in accordance with any of the above, the plurality of studs can attach the louver segment to the outer wall of the combustor.
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Optionally, and in accordance with any of the above, at least a first stud of the plurality of studs can be disposed between the upstream end of the arcuate member and the rib.
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Optionally, and in accordance with any of the above, at least a second stud of the plurality of studs can be disposed between the downstream end of the arcuate member and the rib.
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Optionally, and in accordance with any of the above, the plurality of louver segments can be cast.
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Optionally, and in accordance with any of the above, the arcuate member and the rib of each louver segment form a T-shaped cross-section in a cross-section taken along the axis.
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Optionally, and in accordance with any of the above, the combustor can further include an aperture extending through the outer wall to fluidly connect a plenum exterior to the combustion chamber to a region between one of the louver segments and the outer wall.
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Optionally, and in accordance with any of the above, each arcuate member of the plurality of louver segments can be spaced from and can conform to the outer wall of the combustor.
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While the invention has been described with reference to an exemplary embodiment(s), it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiment(s) disclosed, but that the invention will include all embodiments falling within the scope of the appended claims.