Patent Application
20170350269
The subject matter disclosed herein relates to the art of turbomachines and, more particularly, to a passive clearance control system for a turbine portion of a gas turbomachine.
Gas turbomachines typically include a compressor portion, a turbine portion, and a combustor assembly. The combustor assembly mixes fluid from the compressor portion with a fuel to form a combustible mixture. The combustible mixture is combusted forming hot gases that pass along a hot gas path of the turbine portion. The turbine portion includes a number of stages having airfoils mounted to rotors that convert thermal energy from the hot gases into mechanical, rotational energy. Additional fluid from the compressor is passed through a shell of the gas turbomachine for cooling purposes.
According to one aspect of an exemplary embodiment, a turbomachine includes a compressor portion, and a turbine portion operatively connected to the compressor portion. The turbine portion includes a turbine casing, a plurality of stators fixedly mounted to the turbine casing, and a plurality of rotating airfoils rotatably supported in the turbine casing. A combustor assembly, including at least one combustor, fluidically connects the compressor portion and the turbine portion. At least one of the compressor portion, turbine portion, and combustor assembly includes a sensing cavity configured to contain a fluid having a fluid parameter indicative of a desired operational mode of the turbomachine. A passive clearance control system is operatively arranged in the turbomachine. The passive clearance control system includes at least one passive flow modulating device mounted in the sensing cavity and is responsive to the fluid parameter, and at least one cooling channel extending from the sensing cavity through the casing. The at least one passive flow modulating device selectively passes the fluid from the sensing cavity through the at least one cooling channel to adjust a clearance between the plurality of stators and the plurality of rotating airfoils.
According to another aspect of an exemplary embodiment, a turbomachine system includes a compressor portion and a turbine portion operatively connected to the compressor portion. The turbine portion includes a turbine casing, a plurality of stators fixedly mounted to the turbine casing, and a plurality of rotating airfoils rotatably supported in the turbine casing. An intake system is fluidically coupled to the compressor portion. The intake system is operative to condition a flow of intake air to the compressor portion. An exhaust system is fluidically connected to the turbine portion. The exhaust system is operative to condition a flow of exhaust gases passing from the turbine portion. A load is operatively connected to one of the turbine portion and the compressor portion. A combustor assembly, including at least one combustor, fluidically connects the compressor portion and the turbine portion. At least one of the compressor portion, turbine portion, and combustor assembly includes a sensing cavity configured to contain a fluid having a fluid parameter indicative of a desired operational mode of the turbomachine. A passive clearance control system is operatively arranged in the turbomachine. The passive clearance control system includes at least one passive flow modulating device mounted in the sensing cavity and is responsive to the fluid parameter, and at least one cooling channel extends from the sensing cavity through the turbine casing. The at least one passive flow modulating device selectively passes the fluid from the sensing cavity through the at least one cooling channel to adjust a clearance between the plurality of stators and the plurality of rotating airfoils.
According to yet another aspect of an exemplary embodiment, a method of adjusting rotor blade-to-stator clearance in a turbomachine includes sensing a fluid parameter of a fluid in a sensing cavity of the turbomachine indicative of a desired operating mode of the turbomachine, and actuating at least one passive flow modulating device in response to the fluid parameter, and passing the fluid from the sensing cavity to one or more cooling channels extending through a casing of a turbine portion to passively adjust rotor blade-to-stator clearance in the turbine portion.
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 disclosure, 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 disclosure are apparent from the following detailed description taken in conjunction with the accompanying drawings in which:
The detailed description explains embodiments of the disclosure, together with advantages and features, by way of example with reference to the drawings.
A turbomachine system, in accordance with an exemplary embodiment, is indicated generally at 2, in
In operation, air is passed through intake system 16 into compressor portion 6. Intake system 16 may condition the air by, for example, lowering humidity, altering temperature, and the like. The air is compressed through multiple stages of compressor portion 6 and is passed to turbine portion 8 and combustor assembly 12. The air is mixed with fuel, diluents, and the like, in combustor 14 to form a combustible mixture. The combustible mixture is passed from combustor 14 into turbine portion 8 via transition piece 15 as hot gases. The hot gases flow along a hot gas path 22 of turbine portion 8. The hot gases interact with one or more stationary airfoils, such as shown at 24, and rotating airfoils, such as shown at 25, to produce work. The hot gases then pass as exhaust into an exhaust system 20. The exhaust may be treated and expelled to ambient or used as a heat source in another device (not shown).
In accordance with an exemplary embodiment, turbomachine 4 includes a casing or shell 30 having a compressor section 32 that surrounds compressor portion 6 and a turbine section 34 that surrounds turbine portion 8. Compressor section 32 includes a compressor discharge cavity (CDC) 38 that leads a portion of the compressed air into turbine portion 8 as cooling gas. In the exemplary embodiment shown, CDC 38 may take the form of a sensing cavity 40 that may contain a fluid having a fluid parameter, such as for example, pressure and/or temperature, indicative of a desired operational mode of turbomachine 4.
In accordance with an aspect of an exemplary embodiment illustrated in
In addition, casing 30 includes a plurality of cooling channels 54 extending through turbine section 34 and arranged in a heat exchange relationship with hook members 47. As each of the plurality of cooling channels 54 is substantially similar, a detailed description will follow to one of the plurality of cooling channels indicated at 56 with an understanding that others of the plurality of cooling channels may be similarly formed. Cooling channel 56 includes a first end 59 exposed to sensing cavity 40, a second end 60 and an outlet 62. Outlet 62 may be fluidically connected with stationary airfoil 24. A baffle member 64 may be arranged in cooling channel 56 to establish a desired residence time of cooling air along hook members 47.
In accordance with an aspect of an exemplary embodiment, turbomachine 4 includes a passive clearance control system 70 that passively adjusts a clearance between tip portions (not separately labeled) of rotating airfoils 25 and shrouds (also not separately labeled) supported from hook members 47. By “passive” it should be understood that clearances are autonomously adjusted based solely on turbomachine parameters without the intervention of external programmed control systems and/or personnel.
In accordance with an aspect of an exemplary embodiment, passive clearance control system 70 includes a passive flow modulating device 75 fluidically exposed to sensing cavity 40. In an aspect of an exemplary embodiment, passive flow modulating device 75 may take the form of a valve 80 arranged in sensing cavity 40. Valve 80 may be responsive to pressure and/or temperature of fluid in sensing cavity 40. The pressure and/or temperature of the fluid may be indicative of a desired operational parameter of turbomachine 4. At a predetermined temperature and/or pressure, valve 80 may open passing cooling fluid from sensing cavity 40 through cooling channels 54. In this manner, casing 30 may adjust a desired clearance between rotating airfoils 25 and internal surfaces of casing 30. In accordance with an aspect of an exemplary embodiment, passive flow modulating device 75 may operate as an integrated sensor, actuator and valve that controls a flow of coolant from sensing cavity 40 to cooling channels 54.
In accordance with an aspect of an exemplary embodiment illustrated in
In accordance with an aspect of an exemplary embodiment, turbine section 34 of casing 30 defines a casing volume VC. In further accordance with an exemplary embodiment, plurality of cooling channels 54 collectively defines a channel volume VCh. In accordance with an aspect of an exemplary embodiment, casing volume VC and channel volume VCh define a volume ratio of about 0.0002<VCh/VC<0.9. In accordance with another aspect of an exemplary embodiment, casing volume VC and channel volume VCh define a volume ratio of about 0.01<VCh/VC<0.74. The volume ratio ensures a desired cooling for casing 30 while also maintaining a desired operational efficiency of turbomachine 4.
At this point, it should be understood that exemplary embodiments describe a system for passively controlling running clearances in a turbomachine. More specifically, the system employs a valve responsive to a fluid parameter indicative of an operating condition of the turbomachine. In response to detecting a desired operating parameter, the passive flow modulating device selectively controls a flow of cooling fluid through a turbine shell. The cooling fluid passes in a heat exchange relationship with turbine casing. The casing expands and/or contracts resulting from a presence and/or absence of cooling fluid. The expansion and/or contraction of the casing causes a shifting of the turbine shrouds resulting in a change in or adjustment of turbine running clearance.
The term “about” is intended to include the degree of error associated with measurement of the particular quantity based upon the equipment available at the time of filing the application. For example, “about” can include a range of ±8% or 5%, or 2% of a given value.
The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the disclosure. As used herein, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises” and/or “comprising,” when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, element components, and/or groups thereof.
While the disclosure is provided in detail in connection with only a limited number of embodiments, it should be readily understood that the disclosure is not limited to such disclosed embodiments. Rather, the disclosure 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 disclosure. Additionally, while various embodiments of the disclosure have been described, it is to be understood that the exemplary embodiment(s) may include only some of the described exemplary aspects. Accordingly, the disclosure is not to be seen as limited by the foregoing description, but is only limited by the scope of the appended claims.
