The present invention relates to a combustor assembly including one or more resonator assemblies and a process for forming same.
Gas turbine engines including a can-annular combustion system comprise a compressor and a turbine. The can-annular combustion system comprises a plurality of combustor assemblies and a like number of transition ducts. In one design, these combustor assemblies comprise a combustor casing, a burner assembly, and a combustor liner. Each transition duct connects a corresponding combustor liner to an inlet of the turbine. Compressed air enters each combustor assembly from the compressor, and is mixed with fuel in the burner assembly. The fuel and air mixtures burns within the combustor liner and transition duct, and the combustion products exit the transition duct into the turbine. The coupling of heat release oscillations with the acoustics of the combustor assembly is known to cause combustor acoustic pressure oscillations. These pressure oscillations can occur over a wide range of frequencies, depending upon the geometry of the combustor assembly and the heat release profile within the combustor assembly. These pressure oscillations in the combustor assembly can cause high cycle fatigue, leading to reduced life of combustion assembly components or restricted engine operation.
One known method for controlling combustion acoustic pressure oscillations is to incorporate Helmholtz resonator assemblies into the liner. These resonator assemblies are commonly used to damp high frequency pressure oscillations in gas turbine combustor assemblies. Because the resonator assemblies for controlling high frequency pressure oscillations are typically compact, they can be easily located on the combustor assembly liners. A known resonator assembly comprises a resonator outer plate having a plurality of generally circular openings closely spaced relative to one another and positioned over substantially the entire surface area of the outer plate, a resonator side wall coupled to the resonator outer plate, and a resonator inner plate defined by a portion of the liner. The resonator inner plate is provided with a plurality of closely spaced openings that are located over substantially the entire surface area of the inner plate. Air is supplied through the openings in the outer plate, into an inner cavity defined by the resonator inner and outer plates and side wall and then through the openings in the resonator inner plate. The plurality of resonator assemblies are spaced apart circumferentially about the liner and are generally positioned in alignment in an axial direction.
A thermal barrier coating is applied to a substantial portion of the inner surface of the liner to protect the liner from the hot combustion products passing therethrough. However, the thermal barrier coating can lengthen a neck of each Helmholtz resonator assembly, thus altering its damping performance. Therefore, prior to applying the thermal barrier coating to the liner inner surface, masking material is typically applied over the area where the openings are located so as to prevent thermal barrier coating material from being applied to the inner surfaces of the resonator inner plates. Since the resonator inner plates include a plurality of closely spaced openings, it is impractical to mask only the areas adjacent to the openings while leaving the areas between the openings unmasked. Therefore masking material is typically applied in a circumferential band to the inner surface of the liner. This masking technique prevents thermal barrier coating material from being applied in the areas adjacent to the resonator assembly openings, but also prevents the thermal barrier coating from being applied to the areas between resonator assemblies. Those unprotected portions of the liner inner surface are exposed to the hot combustion products passing through the liner and, as a result, require cooling air that flows through the resonator assemblies. A minimum amount of cooling air is required to prevent overheating of the liner, which may result in thermal fatigue of the liner and part failure.
In accordance with a first aspect of the present invention, a combustor assembly is provided comprising a combustor casing; a liner coupled to the combustor casing; a burner assembly coupled to the combustor casing; and at least one resonator assembly. The resonator assembly comprises a resonator outer plate having at least one opening, a resonator side wall coupled to the resonator outer plate, and a resonator inner plate defined by a portion of the liner. The resonator inner plate is coupled to the resonator side wall and has at least one slot formed therein having an aspect ratio of at least 4:1.
The liner comprises a closed curvilinear liner such as a generally cylindrical liner.
In accordance with one embodiment of the present invention, the slot in the resonator inner plate may extend in a circumferential direction of the generally cylindrical liner.
The one opening in the resonator outer plate may be located along an axis generally parallel to and axially spaced from the slot in the resonator inner plate extending in the circumferential direction of the generally cylindrical liner.
The one opening in the resonator outer plate may comprise a slot. Alternatively, the at least one opening in the resonator outer plate may comprise a plurality of openings located along the axis generally parallel to and axially spaced from the slot in the resonator inner plate.
In accordance with a further embodiment of the present invention, the slot or slots in the resonator inner plate may extend in an axial direction of the generally cylindrical liner.
The at least one opening in the resonator outer plate may be located along an axis generally parallel to and circumferentially spaced from the slot in the resonator inner plate extending in the axial direction of the generally cylindrical liner.
The at least one opening in the resonator outer plate may comprise a slot.
Alternatively, the at least one opening in the resonator outer plate may comprise a plurality of openings located along the axis generally parallel to and circumferentially spaced from the slot in the resonator inner plate.
The resonator inner plate may have at least 50% of its inner surface coated with thermal barrier coating material.
In accordance with a second aspect of the present invention, a process is provided for forming a plurality of resonator assemblies comprising: providing a generally cylindrical liner having a plurality of slots, each having an aspect ratio of at least 4:1; providing a plurality of resonator outer plates, each having at least one opening; providing a plurality of resonator side walls, each being coupled to a corresponding one of the resonator outer plates; coupling each of the resonator side walls to an outer surface of the liner such that each side wall encompasses a corresponding one of the slots; applying masking material to portions of an inner surface of the liner near the slots while leaving an unmasked portion located between adjacent masked portions; applying a thermal barrier coating on the inner surface of the liner; and removing the masking material from the liner inner surface such that the thermal barrier coating does not cover the portions to which the masking material was applied.
Applying masking material comprises applying the masking material so as to encompass each of the slots in the generally cylindrical liner. Preferably, the masking material extends away from each of the slots no more than about 4 mm.
In the following detailed description of the preferred embodiments, reference is made to the accompanying drawings that form a part hereof, and which is shown by way of illustration, and not by way of limitation, specific preferred embodiments in which the invention may be utilized and that changes may be made without departing from the spirit and scope of the present invention.
A portion of a can-annular combustion system 10, constructed in accordance with the present invention, is illustrated in
The can-annular combustion system 10 comprises a plurality of combustor assemblies 30 and a like number of corresponding transition ducts 20. The combustor assemblies 30 and transition ducts 20 are spaced circumferentially apart so as to be positioned about an outer shell 12 of the gas turbine engine. Each transition duct 20 receives combustion products from its corresponding combustor assembly 30 and defines a path for those combustion products to flow from the combustor assembly 30 to the turbine.
Only a single combustor assembly 30 is illustrated in
The combustor assembly 30 comprises a combustor casing 32 coupled to the outer shell 12 of the gas turbine engine, see
A plurality of resonator assemblies 40 constructed in accordance with a first embodiment of the present invention are spaced apart circumferentially about the liner 34, see
The resonator assembly 40 comprises a resonator outer plate 42 having a plurality of openings 42A, which, in the illustrated embodiment, are elliptical and aligned along an axis A1, see
A resonator assembly 140 constructed in accordance with a second embodiment of the present invention is illustrated in
A resonator assembly 240 constructed in accordance with a third embodiment of the present invention is illustrated in
A resonator assembly 340 constructed in accordance with a fourth embodiment of the present invention is illustrated in
A resonator assembly 440 constructed in accordance with a fifth embodiment of the present invention is illustrated in
A process for forming the combustor assembly 30 including a plurality of resonator assemblies 440 will now be described. A generally cylindrical liner 34 formed, for example, from a high temperature metal alloy, is provided having a plurality of slots 348. The slots 348 are spaced apart circumferentially about the liner 34 by a distance D1. Distance D1 may be equal to or greater than about three times a width W2 of each slot 348, wherein the slot width W2 may be from about 0.5 mm to about 10 mm. Each slot 348 preferably has an aspect ratio of at least 4:1. A plurality of resonator side walls 344, each coupled to a corresponding outer plate 442, are coupled, such as by welding, to an outer surface 34B of the liner 34 so that each side wall 344 encompasses a corresponding one of the slots 348.
Masking material (not shown), such as plug capable of being inserted into each slot 348, is provided so as to overlap portions 134 of an inner surface 34C of the liner 34 where thermal barrier coating material is not to be applied, see
In the illustrated embodiment, an area 115 extending between each pair of slots 348 in the circumferential direction is substantially covered by thermal barrier coating material 52, see
Hence, during operation of the combustion assembly 30 a greater amount of the inner surface 34C of the liner 34 is protected from high temperature combustion gases as compared to the prior art combustor assemblies where masking material was typically applied in circumferential bands.
A process similar to one discussed above with regard to
Masking material (not shown), such as plug capable of being inserted into each slot 48, is provided so as to overlap portions of an inner surface 34C of the liner 34 where thermal barrier coating material is not to be applied. In the illustrated embodiment, each masking material plug is located around a corresponding slot 48 so as to extend outwardly from the slot 48 a width of from about 0.5 mm to about 4 mm. Thereafter, thermal barrier coating material 52 is applied to substantially the entire inner surface 34C of the liner 34. The masking material plugs are then removed. Hence, the previously masked inner surface portions are not covered by thermal barrier coating material. The previously masked inner surface portions in the illustrated embodiment, may have a width of between about 0.5 mm to about 4 mm.
While particular embodiments of the present invention have been illustrated and described, it would be obvious to those skilled in the art that various other changes and modifications can be made without departing from the spirit and scope of the invention. It is therefore intended to cover in the appended claims all such changes and modifications that are within the scope of this invention.
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