Patent Application
20200191006
The present invention relates to gas turbine engines, and more specifically to seals for use in turbine sections of gas turbine engines.
Gas turbine engines, such as those that power modern commercial and military aircraft, typically include a compressor to pressurize inflowing air, a combustor to burn a fuel in the presence of the pressurized air, and a turbine to extract energy from the resulting combustion gases. The turbine may include multiple rotatable blade arrays separated by multiple stationary vane arrays. A turbine blade array is typically situated radially within a blade outer air seal system or assembly (or “BOAS” system or assembly). In other words, a BOAS assembly may span an outer endwall between a plurality of static vane arrays situated upstream and downstream of the blade array. The BOAS assembly thus forms an outer (cylindrical) wall configured to confine a stream of hot post-combustion gases.
Cooling air is often provided to the BOAS assembly to enable operation while exposed to the hot combustion gases. This cooling air may be bled from one or more air compartments situated in proximity to the BOAS assembly and through one or more bleed apertures disposed within the BOAS assembly. A higher pressure is typically required to direct cooling air through the BOAS assembly. Effective seals may prevent leakage of cooling air between the BOAS assembly and adjacent component assemblies (e.g., vanes, vane arrays, and vane supports), thus allowing cooling air to flow within segments of the BOAS assembly.
As the turbine is heated by the combustor exhaust and pressurized, the cooling air may undesirably escape into the turbine through a variety of gaps between the BOAS assembly and adjacent vane arrays and other pathways formed as a result of thermal and maneuvering stresses placed upon the engine parts during operation.
Brush seals are one kind of seal that has been used to close gaps between BOAS assemblies and adjacent component assemblies. Traditionally, brush seals include wire bristles that are fixed between two plates. Manufacturing wire bristle brush seals requires many steps and is costly. First, each bristle must be cut to length, then the bristles are packed and held between the two plates. Finally, every bristle must be welded to the surrounding bristles and the two plates. If gaps are present between bristles, gas leakage can occur through the brush seal. Gas leakage across the brush seal can impair the performance and efficiency of the gas turbine engine, such as reduced flow output and decreased fuel efficiency.
In one aspect of the disclosure, a seal assembly includes a first annular plate extending axially between a first end and a second end. A second annular plate is radially inward from the first annular plate, and the second annular plate extends axially between a first end and a second end. At least two layers of metal tape are between the first annular plate and the second annular plate. A first layer and a second layer of the at least two layers of metal tape each include a metal sheet and a plurality of cuts. The metal sheet extends axially between a first end and a second end, and the second end of the metal sheet is axially forward or aft of the first annular plate and the second annular plate. The plurality of cuts are in the second end of the metal sheet and form a plurality of strips in the second end of the metal sheet.
In another aspect of the disclosure, a seal assembly includes an annular plate extending axially between a first end and a second end. At least two layers of metal tape are stacked around the annular plate. Each layer of the at least two layers of metal tape includes a metal sheet extending axially between a first end and a second end. The second end of the metal sheet is axially forward or aft of the annular plate, and a plurality of strips is formed on the second end of the metal sheet.
In another aspect of the invention, a seal assembly includes a plate, a first sheet metal layer connected to the plate, and a second sheet metal layer connected to the plate. A first plurality of cuts in the first sheet metal layer forms a first plurality of flat bristles in the first sheet metal layer. A second plurality of cuts in the second sheet metal layer forms a second plurality of flat bristles in the second sheet metal layer.
Persons of ordinary skill in the art will recognize that other aspects and embodiments of the present invention are possible in view of the entirety of the present disclosure, including the accompanying figures.
While the above-identified drawing figures set forth one or more embodiments of the invention, other embodiments are also contemplated. In all cases, this disclosure presents the invention by way of representation and not limitation. It should be understood that numerous other modifications and embodiments can be devised by those skilled in the art, which fall within the scope and spirit of the principles of the invention. The figures may not be drawn to scale, and applications and embodiments of the present invention may include features and components not specifically shown in the drawings. Like reference numerals identify similar structural elements.
This disclosure relates to a seal assembly that includes multiple layers of sheet metal tape connected to a plate. Strips are cut into each of the layers of the sheet metal tape to form flat bristles. The strips in each layer are circumferentially offset from the strips in the adjacent layers so that the strips overlap and cover the seams between the strips in the adjacent layers, thereby minimizing leakage paths through the strips of the seal assembly. This seal assembly is relatively easy to assemble in comparison to traditional wire bristle seals because the strips within each layer are connected together prior to being assembled with the other layers. This seal assembly also allows easier control of the position of the strips during assembly over traditional wire bristles because the strips within a single layer are connected into a circumferential row that can shifted circumferentially to offset the strips in the row with the strips in adjoining rows. The ability to control the position of each row of strips provides the ability to make sure seams between strips do not line up with seams in neighboring rows, thereby reducing gas leakage through the layers of sheet metal tape of the seal assembly. The seal assembly is discussed below with reference to the figures.
In the embodiment of
Metal tape layers 14 are positioned between first plate 12 and second plate 16. In the embodiment of
Metal sheet 27 of each metal tape layer 14 is axially longer than first plate 12 and second plate 16 such that second end 26 of each metal tape layer 14 extends axially aft of first plate 12 and second plate 16. Cuts 28 are made in each metal tape layer 14 at second end 26 and extend axially toward first end 24. Cuts 28 are also spaced circumferentially from each other to form strips 30 on second end 26 of each metal tape layer 14. Cuts 28 form seams between adjacent strips 30 within the same metal tape layer 14. Each of cuts 28 start at second end 26 of their respective metal tape layer 14, and each of cuts 28 terminates axially on their respective metal tape layer 14 between first end 20 and second end 22 of first plate 12. In the embodiment of
Strips 30 of seal assembly 10 can be used in a gas turbine engine (not shown) to close and seal a gap between two neighboring components, such as a gap between blade outer air seal (commonly referred to as BOAS) and an adjacent vane pack in a turbine section. During the assembling process of seal assembly 10, mandrel 18 is positioned against second plate 16 opposite metal tape layers 14. One method for assembling seal assembly 10 is discussed below with reference to
Mandrel 18 is annular and extends circumferentially around center axis CA from first circumferential end 38 to second circumferential end 40. Mandrel 18 can be formed from steel or any other material with enough elasticity to allow first circumferential end 38 and second circumferential end 40 to spread apart to receive attachment shoe 36. Attachment shoe 36 is a tapered wedge that fits between first circumferential end 38 and second circumferential end 40 of mandrel 18. During the assembly of seal assembly 10, attachment shoe 36 is first inserted between first circumferential end 38 and second circumferential end 40. Attachment shoe 36 is sized so as to displace second circumferential end 40 radially outward from first circumferential end 38 approximately the same distance as the thickness of a single metal tape layer 14. Second plate 16 is then connected to attachment shoe 36 and wrapped circumferentially around mandrel 18. Second plate 16 can be connected to attachment shoe 36 via welding, fasteners, or adhesive.
Metal tape layers 14 can be provided to seal assembly 10 from a length of metal tape 14 wound into a spool on a roll (not shown). Strips 30 (shown in
After strips 30 are formed and polished, the length of metal tape 14 is wound into a spool on a roller. The length of metal tape 14 is then connected by one end to second plate 16 and attachment shoe 36 and then spiral wound around second plate 16 and mandrel 18 several times to form multiple metal tape layers 14 around second plate 16. First plate 12 is connected to attachment shoe 36 over metal tape layers 14 and wrapped around metal tape layers 14, first plate 16, and mandrel 18.
Next, first plate 12, metal tape layers 14, and second plate 16 are welded or otherwise joined together. First cut 42a is made through first plate 12, metal tape layers 14, and second plate 16 at the interface between attachment shoe 36 and first circumferential end 38 of mandrel 18. First cut 42a forms first joining end 44a of seal assembly 10. Second cut 42b is made through metal tape layers 14 at the interface between attachment shoe 36 and second circumferential end 40 of mandrel 18. Second cut 42b forms second joining end 44b. Attachment shoe 36 and the portions of first plate 12, metal tape layers 14, and second plate 16 connected to attachment shoe 36 are removed. With the removal of attachment shoe 36, first circumferential end 38 and second circumferential end 40 of mandrel 18 spring back together.
First joining end 44a and second joining end 44b can both be machined such that first joining end 44a and second joining end 44b can form a lap joint (not shown). First joining end 44a and second joining end 44b can be machined into a lap joint while seal assembly 10 is still on mandrel 18. First circumferential end 38 and second circumferential end 40 of mandrel 18 can be sacrificed in the process of forming first joining end 44a and second joining end 44b into a lap joint. After the split ring embodiment of seal assembly 10 is completely assembled and removed from mandrel 18, seal assembly 10 can be installed within a gas turbine engine (not shown).
A single metal tape layer 14 is then individually wrapped around second plate 16 and formed into a continuous annular shape. One-by-one, additional metal tape layers 14 are wrapped around the second plate 16 and mandrel 18 until all metal tape layers 14 have been assembled around second plate 16 and mandrel 18. Strips 30 (shown in
First plate 12 is then wrapped into a continuous annular shape around metal tape layers 14, second plate 16, and mandrel 18. First plate 12 can be annular before being assembled around metal tape layers 14, or first plate 12 can be formed into the annular shape as first plate 12 is being assembled around metal tape layers 14. First plate 12, metal tape layers 14, and second plate 16 can be welded or otherwise joined together before seal assembly 10 is removed from mandrel 18. The embodiment of seal assembly 10 of
In the embodiment of
Similar to the embodiment of
In view of the foregoing description, it will be recognized that the present disclosure provides numerous advantages and benefits. For example, the present disclosure provides seal assembly 10 with multiple metal tape layers 14 connected between first plate 12 and second plate 16. Strips 28 are cut into each metal tape layer 14 to form flat bristles. Strips 28 in each metal tape layer 14 are circumferentially offset from the strips 28 in adjacent metal tape layers 14 so that strips 28 overlap and cover the seams between strips 28 in the adjacent metal tape layers 14, thereby eliminating leakage paths through strips 28. Seal assembly 10 is relatively easy to assemble in comparison to traditional wire bristle seals because strips 28 within each metal tape layer 14 are connected together prior to being assembled with the other metal tape layers 14. Instead of welding hundreds or even thousands of individual wire bristles together into a brush seal assembly, a manufacturer need only weld several layers of metal tape together to form seal assembly 10. Seal assembly 10 also allows easier control of the position of strips 28 during assembly over traditional wire bristles because strips 28 within each metal tape layer 14 can be cut into a specific pattern so that strips 28 are circumferentially offset with strips 28 in adjacent layers. The ability to control the position of strips 28 provides the ability to make sure seams between strips 28 do not line up with seams in neighboring layers, thereby reducing gas leakage through sheet metal layers 14 of seal assembly 10.
The following are non-exclusive descriptions of possible embodiments of the present invention.
In one embodiment, a seal assembly includes a first annular plate extending axially between a first end and a second end. A second annular plate is radially inward from the first annular plate, and the second annular plate extends axially between a first end and a second end. At least two layers of metal tape are between the first annular plate and the second annular plate. A first layer and a second layer of the at least two layers of metal tape each include a metal sheet and a plurality of cuts. The metal sheet extends axially between a first end and a second end, and the second end of the metal sheet is axially forward or aft of the first annular plate and the second annular plate. The plurality of cuts are in the second end of the metal sheet and form a plurality of strips in the second end of the metal sheet.
The seal assembly of the preceding paragraph can optionally include, additionally and/or alternatively, any one or more of the following features, configurations and/or additional components:
the plurality of strips in the first layer overlap the plurality of cuts in the second layer;
the second end of the metal sheet extends axially aft of the first annular plate and the second annular plate, and wherein the first end of the metal sheet is connected to the first end of the first annular plate and the first end of the second annular plate;
the second end of the metal sheet extends axially aft of the first annular plate and the second annular plate, wherein the first end of the metal sheet extends axially forward of the first annular plate and the second annular plate, and wherein a second plurality of strips are formed in the first end of the metal sheet by a second plurality of cuts;
the second plurality of strips in the first layer overlap the second plurality of cuts in the second layer;
a method of manufacturing the seal assembly includes: making the plurality of cuts in the metal tape to form the plurality of strips; wrapping the metal tape around the second annular plate; placing the second annular plate around the metal tape and the second annular plate; and welding the first annular plate, the metal tape, and the second annular plate together; and/or
wrapping the metal tape around the second annular plate comprises spiral winding the metal tape around the second annular plate.
In another embodiment, a seal assembly includes an annular plate extending axially between a first end and a second end. At least two layers of metal tape are stacked around the annular plate. Each layer of the at least two layers of metal tape includes a metal sheet extending axially between a first end and a second end. The second end of the metal sheet is axially forward or aft of the annular plate, and a plurality of strips is formed on the second end of the metal sheet.
The seal assembly of the preceding paragraph can optionally include, additionally and/or alternatively, any one or more of the following features, configurations and/or additional components:
the at least two layers of metal tape comprise: a first layer of metal tape extending circumferentially around a center axis of the seal assembly; and a second layer of metal tape radially inward from the first layer and extending circumferentially around a center axis of the seal assembly;
the plurality of strips in the first layer are circumferentially offset with the plurality of strips in the second layer such that the plurality of strips in the first layer over lap seams between the plurality of strips in the second layer;
the plurality of strips in the first layer and the plurality of strips in the second layer extend axially aft of the annular plate;
the first end of the metal sheet in the first layer and the first end of the metal sheet in the second layer are both connected to the annular plate; and/or
the first end of the metal sheet in the first layer and the first end of the metal sheet in the second layer both extend axially forward of the annular plate, and a second plurality of strips are formed on the first end of the metal sheet in the first layer and the first end of the metal sheet in the second layer.
In another embodiment, a seal assembly includes a plate, a first sheet metal layer connected to the plate, and a second sheet metal layer connected to the plate. A first plurality of cuts in the first sheet metal layer forms a first plurality of flat bristles in the first sheet metal layer. A second plurality of cuts in the second sheet metal layer forms a second plurality of flat bristles in the second sheet metal layer.
The seal assembly of the preceding paragraph can optionally include, additionally and/or alternatively, any one or more of the following features, configurations and/or additional components:
the plate is annular and extends circumferentially around a center axis of the seal assembly;
the first sheet metal layer and the second sheet metal layer are both annular and extend circumferentially around the center axis of the seal assembly;
the first plurality of flat bristles and the second plurality of flat bristles both extend axially aft of the plate;
the first plurality of flat bristles and the second plurality of flat bristles both extend axially forward of the plate;
the flat bristles in the first plurality of flat bristles overlap the second plurality of cuts; and/or
a second plate, wherein the first sheet metal layer and the second sheet metal layer are connected between the plate and the second plate.
Any relative terms or terms of degree used herein, such as “substantially”, “essentially”, “generally”, “approximately”, and the like, should be interpreted in accordance with and subject to any applicable definitions or limits expressly stated herein. In all instances, any relative terms or terms of degree used herein should be interpreted to broadly encompass any relevant disclosed embodiments as well as such ranges or variations as would be understood by a person of ordinary skill in the art in view of the entirety of the present disclosure, such as to encompass ordinary manufacturing tolerance variations, incidental alignment variations, transitory vibrations and sway movements, temporary alignment or shape variations induced by operational conditions, and the like.
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. For example, while
