Patent Application
20180230838
This invention relates generally to gas turbines, and more particularly to seals between components of a gas turbine, such as turbine shroud segments.
In a gas turbine, a combustor converts chemical energy of a fuel or an air-fuel mixture into thermal energy. The thermal energy is eventually converted to mechanical energy as exhaust gases pass through the turbine. The gases force one or more turbine blades to rotate a shaft along an axis of the system. The shaft may be connected to various components of the turbine system, including a compressor. The compressor also includes blades that may be coupled to the shaft. As the shaft rotates, the blades within the compressor also rotate, thereby compressing air from an air intake through the compressor and into the fuel nozzles and/or combustor. Air may be bled off from the compressor to cool various components of the turbine. For example, compressor air may be bled off to cool a turbine shroud. The cooling air may also be used to pressurized seals between segments of the shroud.
One exemplary but nonlimiting aspect of the disclosed technology relates to a shroud segment for a turbomachine comprising a body configured to be positioned radially outward of a gas flow path of the turbomachine, said body having a plurality of walls defining an internal pocket for receiving a supply of air; at least one pressurization aperture formed in at least one wall of the plurality of walls, the at least one pressurization aperture fluidly connecting the internal pocket to an ambient area of the body; and at least one seal slot section formed in the at least one wall at a position radially inward of the at least one pressurization aperture, wherein the at least one pressurization aperture is arranged such that portions of the supply of air are configured to pass through the pressurization aperture and through the at least one seal slot section as leakage into the gas flow path, thereby reducing ingestion of fluid from the gas flow path into the internal pocket.
Another aspect of the disclosed technology relates to a shroud assembly for a turbomachine adapted to be positioned radially outward of a gas flow path of the turbomachine comprising a first shroud segment having a first body including: 1) a first hollow internal pocket for receiving a first supply of air, and 2) at least one first pressurization aperture formed in at least one wall of the first body to fluidly connect the first internal pocket to an ambient area of the first body; a second shroud segment positioned adjacent the first shroud segment and forming an intersegment cavity therebetween, the second shroud segment having a second body including: 1) a second hollow internal pocket for receiving a second supply of air, and 2) at least one second pressurization aperture formed in at least one wall of the second body to fluidly connect the second internal pocket to an ambient area of the second body; and a seal positioned in the intersegment cavity at a position radially inward of the at least one first pressurization aperture and the at least one second pressurization aperture, wherein the first supply of air and the second supply of air pressurize the seal, respectively, via the at least one first pressurization aperture and the at least one second pressurization aperture such that portions of the first supply of air and the second supply of air are configured to flow past the seal as leakage into the gas flow path, thereby reducing ingestion of fluid from the gas flow path into the first internal pocket and/or the second internal pocket.
Other aspects, features, and advantages of this technology will become apparent from the following detailed description when taken in conjunction with the accompanying drawings, which are a part of this disclosure and which illustrate, by way of example, principles of this invention.
The accompanying drawings facilitate an understanding of the various examples of this technology. In such drawings:
The combustor 104 may use liquid and/or gas fuel, such as natural gas or a hydrogen rich synthetic gas, to run the engine. For example, fuel nozzles 110 are in fluid communication with an air supply and a fuel supply 112. The fuel nozzles 110 create an air-fuel mixture, and discharge the air-fuel mixture into the combustor 104, thereby causing a combustion that heats a pressurized gas. The combustor 104 directs the hot pressurized exhaust gas through a transition piece into a turbine nozzle (or “stage one nozzle”) and then a turbine bucket, causing turbine 106 to rotate. The rotation of turbine 106 causes the shaft 108 to rotate, thereby compressing the air as it flows into the compressor 102. The turbine components or parts are joined by seals or seal assemblies configured to allow for thermal expansion and relative movement of the parts while preventing leakage of the gas. Specifically, reducing leakage of compressed gas flow between turbine components increases hot gas flow along the desired path, enabling work to be extracted from more of the hot gas, leading to improved turbine efficiency. Seals and seal assemblies for placement between turbine parts are discussed in detail below with reference to
Turning to
The upstream side 312 of shroud segment 300 includes upstream static interface structure 332 and upstream turbine shell interface structure 322. The upstream static interface structure 332 is configured to connect the shroud segment 300 to the upstream static nozzle 204, whereas the upstream turbine shell interface structure 322 is configured to connect the shroud segment 300 to an upstream portion of turbine shell 214. However, as those in the art will recognize, the gas turbine may have a different arrangement.
The downstream side 314 of shroud segment 300 includes downstream static interface structure 334 and downstream turbine shell interface structure 324. The downstream static interface structure 334 is configured to connect the shroud segment to the downstream static nozzle 208, whereas the downstream turbine shell interface structure 324 is configured to connect the shroud segment 300 to a downstream portion of the turbine shell.
Shroud segment 300 is positioned radially outward of hot gas path 202, as shown in
As shown in
Turning to
Turning back to
As can been seen in
Turning to
Referring to
When P2 is greater than P3, the pressurization flow 374 will flow through the bottom section 340 of the seal slot and exit the intersegment cavity 402 into the gas path flow as leakage 375. This arrangement is desirable as it prevents ingestion of fluid from the gas flow path into the internal pockets 318 of the shroud segments 300.
It is noted that each shroud segment 300 is essentially self-contained since air does not flow from one shroud segment to another shroud segment. By this arrangement, a leakage issue in one shroud segment will not necessarily affect the other shroud segments.
While the invention has been described in connection with what is presently considered to be the most practical and preferred examples, it is to be understood that the invention is not to be limited to the disclosed examples, but on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.
