Patent Application
20170030212
The present invention relates generally to the art of turbomachines, and, more specifically, to a near flow path seal for a turbomachine and method of repairing the near flow path seal.
Turbomachines include a casing that houses a turbine. The turbine includes a plurality of blades or buckets that extend along a gas path. The buckets are supported by a number of turbine rotors that define a plurality of turbine stages. A combustor assembly generates hot gases that are passed through a transition piece toward the plurality of turbine stages. In addition to hot gases from the combustor assembly, gases at a lower temperature flow from a compressor toward a wheelspace of the turbine. The lower temperature gases provide cooling for the rotors as well as other internal components of the turbine. In order to prevent hot gases from entering the wheelspace, the turbine includes near flow path seals that are arranged between adjacent rotors. The near flow path seals are configured to fit closely adjacent the rotors or buckets to reduce leakage from the gas path into the wheelspace.
Near flow path seals typically include seal elements, also referred to as teeth, that are in rotational contact with a stator positioned between adjacent buckets. Conventionally, the stator includes a honeycomb region typically composed of a nickel alloy, which is in rotational contact with seal elements of the near flow path seals, which are also typically composed of a nickel alloy. The chemical affinity between seal elements and honeycomb enables galling to take place and results in cracks propagating from tips of the seal elements in premature failures.
In addition, conventional near flow path seals and seal elements are typically molded as a single part. Due to the elongated and typically thin profiles of the seal elements, the molding temperature is further elevated to ensure the material properly flows into and fills the portion of the seal elements. The resulting grain structure of the dovetail section may be enlarged, which can adversely affect material properties, such as producing reduced fatigue properties.
The present invention is directed to a near flow path seal member for a turbomachine including a seal body having a first end portion extending to a second end portion having a dovetail member. The first end portion includes a third end and a fourth end having a surface extending therebetween and facing away from the dovetail member. The surface having a longitudinal axis extends between the third end and the fourth end. A recess formed in the surface has a geometry to receive a seal element assembly having a base extending to at least one seal element. The seal element assembly is selectively installable or removable from the recess.
The present invention is also directed to a method of repairing a near flow path seal member in an installed position of a turbomachine, including providing a seal body having a first end portion extending to a second end portion having a dovetail member. The first end portion includes a third end and a fourth end defining a surface extending therebetween and facing away from the dovetail member. The surface has a longitudinal axis extending between the third end and the fourth end. A recess formed in the surface has a geometry to receive a seal element assembly having a base extending to at least one seal element. The seal element assembly has been previously installed. The method further includes removing the seal element assembly and installing another seal element assembly.
Other features and advantages of the present invention will be apparent from the following more detailed description of the preferred embodiment, taken in conjunction with the accompanying drawings which illustrate, by way of example, the principles of the invention.
With reference to
In the exemplary embodiment shown, turbine portion 6 includes a number of stages, one of which is shown at 20. Of course, it should be understood that the number of stages in turbine portion 6 could vary. Stage 20 includes a plurality of stators or nozzles, one of which is indicated at 24, and a plurality of buckets or blades, one of which is indicated at 26, mounted to a rotor wheel (not shown). In the exemplary embodiment shown, another plurality of blades or buckets, one of which is indicated at 28 is arranged upstream of nozzle 24. Buckets 28 form part of an upstream stage in turbine portion 6. Turbomachine 2 is also shown to include a plurality of near flow path seal members, one of which is indicated at 30 arranged between buckets 26 and 28 and below nozzle 24. Near flow path seal members 30 are mounted to shaft 12 through a seal member rotor 32. Near flow path seal members 30 are configured to prevent an exchange of gases between gas path 18 and a wheelspace 34 of turbomachine 2. At this point it should be understood that turbomachine 2 includes additional near flow path seal members (not shown) arranged between adjacent stages (also not shown) of turbine portion 6.
Reference will now be made to
In one embodiment, seal element assembly 64 and seal body 40 may be composed of different materials. For example, in one embodiment, seal element assembly 64 is composed of the group consisting of cobalt-base alloys, such as L-605, HS-188, FSX-414, nickel-base alloys such as R108, GTD-262, GTD-141+, GTD-141, GTD-111, Rene N2, IN-718, IN-725, IN-706, IN-901, IN-925, Hast-X, IN-625, stainless steels, such as 3XX series and 4XX series may be utilized depending on the ambient temperature in the turbine, ceramic matrix composites (“CMCs”), such as SiC fiber reinforced SiC composites and Alumina fiber reinforced oxide ceramic composites, coating materials overlying the seal element assembly, such as CM-64, Stellite-6, T-800, alumina, silicon carbide, boron nitride and capable of preventing galling when placed in contact with the seal body, or combinations thereof.
In one embodiment, seal body 40 is composed of the group consisting of superalloys, including cobalt-base alloys, such as L-605, HS-188, FSX-414, nickel-base alloys such as R108, GTD-262, GTD-141+, GTD-141, GTD-111, Rene N2, IN-718, IN-725, IN-706, IN-901, IN-925, Hast-X, IN-625, stainless steels, such as 3XX series and 4XX series may be utilized depending on the ambient temperature in the turbine, ceramic matrix composites (“CMCs”), such as SiC fiber reinforced SiC composites and Alumina fiber reinforced oxide ceramic composites, coating materials, such as Stellite-6, LOB1800G, Alumazite, Alumina, Silicon Carbide and Boron Nitride overlying recess 62 and capable of preventing galling and fretting when placed in contact with base 66 of seal element assembly 64, or combinations thereof.
It is to be understood that as a result of seal element assembly 64 being separately manufactured, material selection can be increased to include non-weld-repairable alloys, such as Rene′-108 (MAR M-247 or CM-247), Rene′-142, Rene′-N2, Rene′-N6, Rene′-195, GTD-444, GTD-111, PWA-1480, CMSX-4 that may have greater than about 30 percent by volume of gamma prime particles in their microstructure.
In one embodiment, the geometry of recess 62 is a slot having opposed ends 70, 72 having mating features permitting a slidable engagement/disengagement with base 66 of seal element assembly 64. For example, in one embodiment, ends 70, 72 of recess 62 define mating features such as ends 70, 72 being inwardly directed toward each other to permit slidable engagement with corresponding ends 74, 76 of base 66 of seal element assembly 64. In one embodiment, recess 62 defines mating features such as ends 70, 72 being serrated to permit slidable engagement with corresponding ends 74, 76 of base 66 of seal element assembly 64. It is to be understood that other mating features permitting slidable engagement/disengagement between corresponding ends 74, 76 of base 66 of seal element assembly 64 and ends 70, 72 of recess 62 may be used. In one embodiment, a direction of slidable engagement/disengagement is substantially normal to longitudinal axis 60.
It is to be understood that the term “mating features” is intended to include any portion along surface 58 of first end portion 42 in contact with base 66 of seal element assembly 64.
As further shown in
It is to be understood that slidable disengagement includes removal of deformed portion 78 of the mating features formed in at least one of recess 62 and base 66 of seal element assembly 64 subsequent to disengaging seal element assembly 64 and base 66 of seal element assembly 64 subsequent to disengaging seal element assembly 64.
In one embodiment, removal of deformed portion 78 is achieved by drilling, grinding or other suitable operation usable to remove material from one or more of seal element assembly 64 and seal body 40.
It is to be understood that the seal element assembly may include one or more seal elements.
Once seal element assembly 64 has been removed, the next step, 102 of the process of
While the invention has been described with reference to a preferred embodiment, 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 disclosed as the best mode contemplated for carrying out this invention, but that the invention will include all embodiments falling within the scope of the appended claims.
