Patent Application
20120297792
The subject matter disclosed herein relates to the art of turbomachines and, more particularly, to a thermocouple well for a turbomachine.
In a gas turbomachine, air flows in a wheel space between a stationary component (nozzle) and a rotating wheel. Temperature of the air flow is monitored to detect whether any combustion gases are entering the wheel space. Temperature is monitored using thermocouples arranged in thermocouple wells installed into a diaphragm portion of the nozzle. A typical thermocouple well includes a tip section, a threaded section that is mounted to the diaphragm, and an opening that receives a guide tube and thermocouple wire. Conventional turbomachine designs require that the diaphragm be installed to the nozzle prior to installation of the thermocouple well. After installation to the nozzle, the threaded section of the thermocouple well is secured in a threaded opening formed in an internal surface of the diaphragm. Once mounted, the guide tube is fitted into the opening of the thermocouple well. At this point, the thermocouple wire is fed through the guide tube, and passed up to the tip section. Accordingly, conventional diaphragms must be formed to have a certain minimum radial height to allow for installation of the thermocouple.
According to one aspect of the invention, a turbomachine includes a nozzle having an end portion and an airfoil portion. A diaphragm is mounted to the end portion of the nozzle in a wheel space portion of the turbomachine. The diaphragm includes an external surface and an internal surface. The diaphragm also includes at least one thermocouple well receiving portion formed in one of the internal surface and the external surface. A thermocouple well is mounted in the at least one thermocouple well receiving portion. The thermocouple well includes a first end exposed to the wheel space portion of the turbomachine and a second end exposed at the internal surface of the diaphragm.
According to another aspect of the invention, a method of mounting a thermocouple well in a turbomachine includes mounting a thermocouple well in one of an external surface and an internal surface of a diaphragm, securing the diaphragm to first and second diaphragm mounting members extending from a second end of a nozzle, positioning an end section of a thermocouple guide tube in the nozzle adjacent the thermocouple well. The thermocouple guide tube is spaced from the thermocouple well.
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.
A turbomachine in accordance with an exemplary embodiment is indicated generally at 2 in
Diaphragm 40 includes a body 42 having a first or upstream wall 44, a second or down stream wall 45, and a base wall 46. Upstream wall 44 includes an interior surface 47 and an exterior surface 48, downstream wall 45 includes an interior surface 49 and an exterior surface 50, and base wall 46 includes an interior surface 51 and an exterior surface 52. Diaphragm 40 also includes a plurality of seal members 54-58 provided on exterior surface 52 of base wall 46. Seal members 54-58 create a seal between diaphragm 40 and a rotor wheel 60. Seal members 54-58 are arranged to substantially prevent combustion gases in hot gas path 12 from passing into a wheel space 61. Diaphragm 40 is also shown to include a first nozzle mounting member 62 having a first hook element 63 and a second nozzle mounting member 64 that includes a second hook element 65. Nozzle mounting members 62 and 64 engage with diaphragm mounting members 29 and 33 to secure diaphragm 40 to nozzle 6 creating a nozzle cavity 69. Diaphragm 40 is further shown to include a first thermocouple well receiving portion 80 formed in exterior surface 50 of downstream wall 45, and a second thermocouple well receiving portion 82 formed in exterior surface 52 of base wall 46.
As will be discussed more fully below, diaphragm 40 supports sensors for monitoring gas temperature in wheel space 61 to provide an indication of any combustion gases passing from hot gas path 12. In accordance with the exemplary embodiment, diaphragm 40 includes a first thermocouple well 100 mounted in first thermocouple well receiving portion 80 and a second thermocouple well 104 mounted in second thermocouple well receiving portion 82. As each thermocouple well is substantially similar, a detailed description will follow with reference to
As best shown in
In further accordance with the exemplary embodiment, turbomachine 2 includes a thermocouple guide tube 144. As shown, thermocouple guide tube 144 passes through a cavity (not separately labeled) formed in nozzle 6 toward thermocouple well 100. More specifically, thermocouple guide tube 144 extends from a first end portion (not shown) to a second end section 146 that is positioned circumferentially adjacent diaphragm mounting member 33 and spaced from second end 116 of thermocouple well 100. With this arrangement, a thermocouple wire 150 is passed through thermocouple guide tube 144 toward thermocouple well 100. A terminal end portion 154 of thermocouple wire 150 nests within tip portion 126.
At this point it should be understood, that the thermocouple well in accordance with the exemplary embodiment is installed into an exterior surface of the diaphragm. In this manner, the thermocouple well can be installed prior to mounting the diaphragm. However, it should also be understood that the thermocouple well could be installed in an internal surface of the diaphragm prior to mounting. Installing the thermocouple well prior to mounting the diaphragm allows the diaphragm cavity to be much smaller as there is no longer a need to provide ample space for access to tools and the like. Accordingly, the diaphragm can be designed to have a much smaller profile. The smaller profile allows engineers to decrease an overall size of the turbomachine. The smaller profile of the diaphragm also enables a reduced wheel space volume. The reduced wheel space volume requires less purge flow to prevent ingestion of combustion gases.
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.
