Patent Application
20120207613
The subject matter disclosed herein relates to a component of a turbine bucket platform and, more particularly, to a component of a turbine bucket platform on which a thermal barrier coating (TBC) is applied.
Gas turbines have been used widely in various fields as power sources and include compressors, combustors and turbines. In a gas turbine, air is compressed by the compressor and then combusted along with fuel by the combustor to produce high energy fluids expanded by the turbine to obtain power. As such, a temperature increase for the high energy fluids enhances power generation. Thus, in an effort to derive increased power generation, gas turbines have been recently designed to generate such high energy fluids with increased temperatures.
In order to provide turbine components that can survive and withstand the increased temperatures of the high energy fluids, those components have been made with heat resisting alloys and coated with thermal barrier coating (TBC). While the TBC is intact, the TBC operates by restraining heat conduction into the coated component to thereby prevent damage and extend the component's lifetime. It is often the case, however, that TBC does not remain in this condition and, indeed, TBC may deteriorate and/or peels off from the component at various positions.
According to one aspect of the invention, a component is provided and includes a first surface, a second surface adjacent to and oriented transversely with respect to the first surface and having a pocket formed therein defining a rib along a periphery thereof and a thermal barrier coating (TBC) respectively applied to the first surface and to the second surface at the pocket such that the rib is interposed between the TBC of the first and second surfaces.
According to another aspect of the invention, a turbine bucket platform is provided and includes a first surface of a turbine bucket platform facing a gas path, a second surface of at least one of a slashface adjacent to the turbine bucket platform surface and a surface of the turbine bucket platform facing an aft trench cavity, the second surface having a pocket formed therein defining a rib along a periphery thereof and a thermal barrier coating (TBC) respectively applied to the first surface and to the second surface at the pocket such that the rib is interposed between the TBC of the first and second surfaces.
According to yet another aspect of the invention, a method is provided and includes applying a thermal barrier coating (TBC) to a first surface, forming a pocket in a second surface adjacent to and oriented transversely with respect to the first surface to define a rib along a periphery of the pocket and applying TBC to the second surface at the pocket such that the rib is interposed between the TBC of the first and second surfaces.
These and other advantages and features will become more apparent from the following description taken in conjunction with the drawings.
The subject matter which is regarded as the invention is particularly pointed out and distinctly claimed in the claims at the conclusion of the specification. The foregoing and other features, and advantages of the invention are apparent from the following detailed description taken in conjunction with the accompanying drawings in which:
The detailed description explains embodiments of the invention, together with advantages and features, by way of example with reference to the drawings.
As a consequence of improvements in gas turbine efficiency and emissions levels, combustion exhaust flows produce more substantially uniform temperature profiles in the radial direction. This translates into significant increases in gas temperatures near turbine endwalls where hot gas path surfaces meet adjacent component surfaces. Prevention of heat fluxes due to hot gas ingestion along these surfaces by way of a thermal barrier coating (TBC) application to the surfaces prevents heat fluxes into the component, which subsequently prevents increases in metal temperatures and leads to lengthened component life. The use of TBC also lessens a need for active cooling.
With reference to
The component 10 may be any component of a turbine or a gas or steam turbine in which high energy fluids are expanded for power generation purposes. Thus, the first and second surfaces 20, 40 may each include surfaces facing a gas path along which fluids having relatively high temperatures flow. In general, such relatively high fluid temperatures occur where the fluid temperatures exceed the temperatures of the interior of the component 10 such that the TBC 60 prevents heat flux from the fluid into the component 10 and such that interior temperatures of the component 10 can be maintained below predefined levels. As an example, the component 10 may be a turbine bucket platform 100 of a gas turbine engine. In this case, the first surface 20 includes a surface 101 of the turbine bucket platform 100 that faces a hot gas path. Further, the second surface 40 may include at least one of a surface of a slashface 102, which is disposed adjacent to the surface 101 of the turbine bucket platform 100, and an aft trench cavity facing surface 104 of the turbine bucket platform 100.
With reference to
In accordance with embodiments, as shown in
An exposed edge of the rib 55 or another similar component may be available as a sacrificial environment condition indicator whereby the edge can be used as a tuned real-time health monitoring differential with calibration being related to edge and mate face gap, G, dimensions.
In addition, as shown in
With the construction discussed above, the TBC 60 of the second surface 40 is at least one of coplanar with and/or recessed from the plane of the distal edge 555 of the rib 55. As such, the TBC 60 of the second surface 40 is isolated and separated from the TBC 60 of the first surface 20. Thus, the TBC 60 of the first surface 20 and the TBC 60 of the second surface 40 need not be made of the same materials, need not be formed simultaneously and need not be formed over the interface zone 45. The TBCs 60 therefore do not tend to deteriorate, crack or peel away at the interface zone 45 and expose the materials of the distal edge 555. The exposed materials of the distal edge 555 can be tested for various concerns, such as temperature profiles of the component 10. This testing may be conducted, for example, by way of infrared (IR) imaging of the distal edge 555.
Alternatively, as shown in
Also, as shown in
With reference to
In accordance with embodiments, the forming of the pocket 50 of operation 510 may include at least one or more of electro-dynamic machining (EDM), milling, casting, grinding and/or another similar process. The forming of the pocket 50 of operation 510 may also include forming the pocket 50 with a substantially uniform depth, D, or forming the pocket 50 in accordance with a heat flux characteristic of the component 10. As mentioned above, in the latter case, the depth, D, of the pocket 50 may be non-uniform with, for example, a greatest depth, D, proximate to at least one of a leading and a trailing edge 200, 201 of the first surface 20.
In accordance with further embodiments, the applying of the TBC 60 to the second surface 40 of operation 520 may include stopping TBC 60 application before the pocket 50 is overfilled. In this way, the TBCs 60 of the first and second surfaces 20, 40 can be isolated and separated from one another and the distal edge 555 of the rib 55 can be exposed such that, for example, the material of the rib 55 can be tested (operation 530).
While the invention has been described in detail in connection with only a limited number of embodiments, it should be readily understood that the invention is not limited to such disclosed embodiments. Rather, the invention can be modified to incorporate any number of variations, alterations, substitutions or equivalent arrangements not heretofore described, but which are commensurate with the spirit and scope of the invention. Additionally, while various embodiments of the invention have been described, it is to be understood that aspects of the invention may include only some of the described embodiments. Accordingly, the invention is not to be seen as limited by the foregoing description, but is only limited by the scope of the appended claims.
