Abstract:
An auto thermal valve (ATV) for dual mode passive cooling flow modulation according to an embodiment includes: a gas flow inlet port; a gas flow outlet port; a temperature dependent expandable element; a rod coupled to the temperature expandable element; and a valve disc coupled to a distal end of the rod, the temperature dependent expandable element displacing the valve disc in response to a change in temperature; wherein the valve disc is displaced away from a valve seat by the temperature dependent expandable element at temperatures above and below a range of temperatures to allow a flow of cooling gas to pass from the gas flow inlet port to the gas flow outlet port.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is related to co-pending U.S. application Ser. Nos. ______, GE docket numbers 280686-1 and 283683-1, filed on _______. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    The disclosure relates generally to turbomachines, and more particularly, to an auto thermal valve (ATV) for dual mode passive cooling flow modulation. 
         [0003]    Turbines are widely used in a variety of aviation, industrial, and power generation applications to perform work. Each turbine generally includes alternating stages of peripherally mounted stator vanes and rotating blades. The stator vanes may be attached to a stationary component such as a casing that surrounds the turbine, and the rotating blades may be attached to a rotor located along an axial centerline of the turbine. A compressed working fluid, such as steam, combustion gases, or air, flows along a gas path through the turbine to produce work. The stator vanes accelerate and direct the compressed working fluid onto a subsequent stage of rotating blades to impart motion to the rotating blades, thus turning the rotor and performing work. If any compressed working fluid moves radially outside of the desired flow path, the efficiency of the turbine may be reduced. As a result, the casing surrounding the turbine often includes a radially inner shell of shrouds, often formed in segments. The shrouds surround and define the outer perimeter of the hot gas path and may be located around both stator vanes and rotating blades. 
         [0004]    Turbine shrouds and other turbine components (e.g., blades, nozzles, etc.) are typically cooled in some fashion to remove heat transferred by the hot gas path, A gas such as compressed air from an upstream compressor may be supplied through at least one cooling circuit including one or more cooling passages to cool the turbine shroud and other turbine components. 
         [0005]    Tuning pins may be used to control the flow of cooling gas passing through the cooling passages. The flow of cooling gas may be controlled using the tuning pins according to the operational conditions of the turbine (e.g., a higher flow of cooling gas may be required on a hot day, while a lower flow of cooling gas may be required on a cool day). Such flow control may be provided by manuallyadjusting the tuning pins to regulate the flow of cooling gas as needed. 
       BRIEF DESCRIPTION OF THE INVENTION 
       [0006]    A first aspect of the disclosure provides an auto thermal valve (ATV) for dual mode passive cooling flow modulation, including: a gas flow inlet port; a gas flow outlet port; a temperature dependent expandable element; a rod coupled to the temperature expandable element; and a valve disc coupled to a distal end of the rod, the temperature dependent expandable element displacing the valve disc in response to a change in temperature; wherein the valve disc is displaced away from a valve seat by the temperature dependent expandable element at temperatures above and below a range of temperatures to allow a flow of cooling gas to pass from the gas flow inlet port to the gas flow outlet port. 
         [0007]    A second aspect of the disclosure provides cooling system for a turbine, including: a cooling circuit for cooling a component of the turbine; and an auto thermal valve for dual mode passive cooling flow modulation, the auto thermal valve comprising: a gas flow inlet port; a gas flow outlet port; a temperature dependent expandable element; a rod coupled to the temperature expandable element; and a valve disc coupled to a distal end of the rod, the temperature dependent expandable element displacing the valve disc in response to a change in temperature; wherein the valve disc is displaced away from a valve seat by the temperature dependent expandable element at temperatures above and below a range of temperatures to allow a flow of cooling gas to pass from the gas flow inlet port to the gas flow outlet port into the cooling circuit. 
         [0008]    A third aspect of the disclosure provides an auto thermal valve system for dual mode passive cooling flow modulation in a turbine, including: a first auto thermal valve including: a gas flow inlet port; a gas flow outlet port; a temperature dependent expandable element; a rod coupled to the temperature expandable element; and a valve disc coupled to a distal end of the rod, the temperature dependent expandable element displacing the valve disc in response to a change in temperature; wherein the valve disc is displaced away from a valve seat by the temperature dependent expandable element at temperatures above a range of temperatures to allow a flow of cooling gas to pass from the gas flow inlet port to the gas flow outlet port; and a second auto thermal valve including: a gas flow inlet port; a gas flow outlet port; a temperature dependent expandable element; a rod coupled to the temperature expandable element of the second auto thermal valve; and a valve disc coupled to a distal end of the rod of the second auto thermal valve, the temperature dependent expandable element of the second auto thermal valve displacing the valve disc of the second auto thermal valve in response to a change in temperature; wherein the valve disc of the second auto thermal valve is displaced away from a valve seat of the second auto thermal valve by the temperature dependent expandable element of the second auto thermal valve at temperatures below the range of temperatures to allow a flow of cooling gas to pass from the gas flow inlet port of the second auto thermal valve to the gas flow outlet port of the second auto thermal valve. 
         [0009]    The illustrative aspects of the present disclosure are designed to solve the problems herein described and/or other problems not discussed. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0010]    These and other features of this disclosure will be more readily understood from the following detailed description of the various aspects of the disclosure taken in conjunction with the accompanying drawing that depicts various embodiments of the disclosure. 
           [0011]      FIG. 1  is a schematic diagram of a gas turbine system, according to embodiments. 
           [0012]      FIG. 2  depicts a turbine bucket and shroud, according to embodiments. 
           [0013]      FIG. 3  depicts an auto thermal valve (ATV) in a closed configuration, according to embodiments. 
           [0014]      FIG. 4  depicts the ATV of  FIG. 3  in a hot ambient modulated flow configuration, according to embodiments. 
           [0015]      FIG. 5  depicts the ATV of  FIG. 3  in a cold ambient modulated flow configuration, according to embodiments. 
           [0016]      FIG. 6  depicts a valve disc, according to embodiments. 
           [0017]      FIG. 7  is a chart illustrating temperature-based modulation of a flow of cooling gas, according to embodiments. 
           [0018]      FIG. 8  depicts a turbine bucket and shroud, according to embodiments. 
           [0019]      FIG. 9  depicts an ATV in a closed configuration, according to embodiments. 
           [0020]      FIG. 10  depicts the ATV of  FIG. 9  in an open configuration, according to embodiments. 
           [0021]      FIG. 11  is an end view of the ATV of  FIG. 9 , according to embodiments. 
           [0022]      FIG. 12  is an end view of the ATV of  FIG. 9  in an open configuration, according to embodiments. 
           [0023]      FIG. 13  depicts an ATV in a closed configuration, according to embodiments. 
           [0024]      FIG. 14  depicts the ATV of  FIG. 13  in an open configuration, according to embodiments. 
       
    
    
       [0025]    It is noted that the drawing of the disclosure is not to scale. The drawing is intended to depict only typical aspects of the disclosure, and therefore should not be considered as limiting the scope of the disclosure. In the drawing, like numbering represents like elements between the drawings. 
       DETAILED DESCRIPTION OF THE INVENTION 
       [0026]    The disclosure relates generally to turbomachines, and more particularly, to an auto thermal valve (ATV) for dual mode passive cooling flow modulation. 
         [0027]    Referring now to the drawings, in which like numerals refer to like elements throughout the several views,  FIG. 1  shows a schematic view of gas turbomachine  2  as may be used herein. The gas turbomachine  2  may include a compressor  4 . The compressor  4  compresses an incoming flow of air  6 . The compressor  4  delivers a flow of compressed air  8  to a combustor  10 . The combustor  10  mixes the flow of compressed air  8  with a pressurized flow of fuel  12  and ignites the mixture to create a flow of combustion gases  14 . Although only a single combustor  10  is shown, the gas turbine system  2  may include any number of combustors  10 . The flow of combustion gases  14  is in turn delivered to a turbine  16 . The flow of combustion gases  14  drives the turbine  16  to produce mechanical work. The mechanical work produced in the turbine  16  drives the compressor  4  via a shaft  18 , and may be used to drive an external load  20 , such as an electrical generator and/or the like. 
         [0028]    An example of a turbine bucket  22  of the turbine  16  ( FIG. 1 ) is depicted in  FIG. 2 . The turbine bucket  22  includes a base  24  and a blade  26  coupled to and extending radially outward from the base  24 . A shroud  28  is positioned adjacent the blade  26  to limit the flow of combustion gas bypassing the turbine bucket  22  and not producing any useful work. The shroud  28  may be attached to a casing (not shown). 
         [0029]    The shroud  28 , blade  26 , and/or other turbine components within the hot gas path may be cooled using a flow of cooling gas  30  (air). The flow of cooling gas  30  may be supplied by the compressor  4  of the gas turbomachine  2  and may be provided to/into the shroud  28 , blade  26 , and/or other turbine components via a set of cooling passages. One such cooling passage  32  in the shroud  28  is depicted in  FIG. 2 . 
         [0030]    According to embodiments, the flow of cooling gas  30  into/through various components of the turbine  16  may be controlled using a set (i.e., one or more) of auto thermal valves (ATV)  40 , which provide passive cooling flow modulation. The ATVs  40  may be used, for example, to provide passive flow modulation for hot day wheelspace (WS) and metal temperature control and for cold day backflow margin (BFM) flow control. The ATVs  40  eliminate the need for the above-described tuning pins, which are not capable of providing such passive flow modulation. Although only one ATV  40  is depicted in  FIG. 2 , any number of ATVs  40  may be used to control the flow of cooling gas in the turbine  16 . The passive flow modulation provided by the ATV  40  provides cooling flow savings across the operating range of the turbine  16  and improves the output and efficiency of the turbine  16 . Further, unlike tuning pins, the ATV  40  does not require manual field tuning for different operational conditions, thereby reducing operating costs. 
         [0031]    An ATV  40  for providing dual mode passive cooling flow modulation is depicted in  FIGS. 3-5 . As shown, the ATV  40  includes a valve section  42  including one or more gas flow inlet ports  44  and a gas flow outlet port  46 . The ATV  40  further includes a housing  48  enclosing a bellows or other expandable element  50  containing a thermally expandable material  52 . The thermally expandable material  52  may include, for example, a silicon heat transfer fluid. Any other suitable thermally expandable material  52  that is stable at the operating temperatures of the turbine  16  (e.g., up to 1300° F.) may also be used. 
         [0032]    The expandable element  50  is coupled to a rod  54 . A valve disc  56  is provided at a distal end of the rod  54 . As depicted in  FIG. 6 , the valve disc  56  may include, for example, a central cylindrical section  64  including an outer surface  58 , and opposing frusto-conical end sections  66 ,  68 . Other suitable configurations of the valve disc  56  capable of providing the functionality described herein may also be used. 
         [0033]    Generally, although not required, a fixed portion  30   Fixed  ( FIG. 2 ) of the flow of cooling gas  30  may be provided to the downstream cooling passage  32  ( FIG. 1 ) for cooling purposes. An additional modulated portion  30   Mod  ( FIG. 2 ) of the flow of cooling gas  30  may be selectively provided to the downstream cooling passage  32  via the ATV  40 , depending on ambient temperature and/or other factors. 
         [0034]    The ATV  40  is shown in a closed configuration in  FIG. 3 . That is, in the closed configuration, at least a portion of the outer surface  58  of the valve disc  56  engages at least a portion of the valve seat  60 . In the closed configuration, the flow of cooling gas  30   Mod  is prevented from flowing from the gas flow inlet ports  44  through a valve seat opening  62  and the gas flow outlet port  46  into the downstream cooling passage  32 . 
         [0035]    Referring temporarily to  FIG. 7 , there is shown a chart illustrating temperature-based modulation of the flow of cooling gas  30   Mod  through an ATV  40 , according to embodiments. As stated above, the flow of cooling gas  30   Mod  through the ATV  40  may be in addition to a fixed flow of cooling gas  30   Fixed . Section A of the chart, in which there is no flow of cooling gas  30   Mod  through the ATV  40 , corresponds to the ATV  40  in a closed configuration for a first range of temperatures (e.g., as shown in  FIG. 3 ). 
         [0036]    Referring now to  FIG. 4 , an increase in temperature at the ATV  40  causes an enlargement of the thermally expandable material  52  within the expandable element  50 . This causes the expandable element  50  to extend within the housing  48  as indicated by arrow  70 , forcing the rod  54  and valve disc  56  laterally away from the valve seat  60  towards the gas flow outlet port  46 . When the outer surface  58  of the central cylindrical section  64  of the valve disc  56  no longer contacts the valve seat  60 , a flow of cooling gas  30   Mod  begins to flow from the gas flow inlet ports  44  through the valve seat opening  62  and the gas flow outlet port  46  into the downstream cooling passage  32  ( FIG. 2 ). The flow of cooling gas  30   Mod  increases as the valve disc  56  moves farther away from the valve seat  60  (as the temperature further increases) as more flow area is provided between the frusto-conical end section  66  of the valve disc  56  and the valve seat  60 . Section B of the chart in  FIG. 7  depicts the increase in the flow of cooling gas  30   Mod  through the ATV  40  for a second, higher range of temperatures. 
         [0037]    As depicted in  FIG. 5 , a decrease in temperature causes a contraction of the thermally expandable material  50  within the expandable element  50 . This causes the expandable element  50  to contract within the housing  48  as indicated by arrow  72 , forcing the rod  54  and valve disc  56  laterally away from the valve seat  60  and the gas flow outlet port  46 . When the outer surface  58  of the central cylindrical section  64  of the valve disc  56  no longer contacts the valve seat  60 , a flow of cooling gas  30   Mod  begins to flow from the gas flow inlet ports  44  through the valve seat opening  62  and the gas flow outlet port  46  into the downstream cooling passage  32  ( FIG. 2 ). The flow of cooling gas  30   Mod  increases as the valve disc  56  moves farther away from the valve seat  60  (as the temperature further decreases) as more flow area is provided between the frusto-conical end section  68  of the valve disc  56  and the valve seat  60 . Section C of the chart in  FIG. 7  depicts the increase in the flow of cooling gas  30   Mod  through the ATV  40  for a third, lower range of temperatures. 
         [0038]    As depicted in  FIGS. 3-5 , the ATV  40  provides a flow of cooling gas  30   Mod  in response to the temperature dependent displacement of the valve disc  56 . The configuration of the valve disc  56  allows the cooling gas  30   Mod  to flow through the ATV  40  to serve both functions of controlling BFM (cold day) and controlling WS temperatures (hot day), thereby providing dual mode functionality. 
         [0039]    As detailed below, according to embodiments, a similar functionality may be provided using two individual ATVs in parallel, where one of the ATVs (e.g., ATV  140 A,  FIG. 8 ) is configured to displace a valve disc to an open position at high temperatures (and which is closed at low temperatures), while the second ATV (e.g., ATV  140 B,  FIG. 8 ) is configured to displace a valve disc to an open condition at low temperatures (and which is closed at high temperatures). The passive flow modulation provided by the ATVs  140 A,  140 B provides cooling flow savings across the operating range of the turbine  16  and improves the output and efficiency of the turbine  16 . Further, unlike tuning pins, the ATVs  140 A,  140 B do not require manual field tuning, thereby reducing operating costs. 
         [0040]    The ATV  140 A is depicted in a closed configuration in  FIG. 9  and in an open configuration in  FIG. 10 . The ATV  140 A includes a valve section  142  including one or more gas flow inlet ports  144  and a gas flow outlet port  146 . The ATV  140 A further includes a housing  148  enclosing a bellows or other expandable element  150  containing a thermally expandable material  152 . The thermally expandable material  152  may include, for example, a silicon heat transfer fluid. Any other suitable thermally expandable material  152  that is stable at the operating temperatures of the turbine  16  (e.g., up to 1300° F.) may also be used. 
         [0041]    The expandable element  150  is coupled to a rod  154 . A valve disc  156  is provided at a distal end of the rod  154 . As depicted in  FIG. 9 , the valve disc  156  may have an inwardly directed arcuate surface  158 . Other suitable configurations of the valve disc  156  capable of providing the functionality described herein may also be used. 
         [0042]    The ATV  140 A is shown in a closed configuration in  FIGS. 9 and 11 . In the closed configuration, the arcuate surface  158  of the valve disc  156  sealingly engages a corresponding circular valve seat  160  formed adjacent the gas flow outlet port  146 . In general, the valve disc  156  and valve seat  160  may have any suitable configuration capable of forming a seal to prevent the flow of gas through the gas flow outlet port  146 . In the closed configuration, the flow of cooling gas  30   Mod  is prevented from flowing from the gas flow inlet ports  144  through the gas flow outlet port  146  into the downstream cooling passage  32  ( FIG. 8 ). 
         [0043]    Referring now to  FIGS. 10 and 12 , an increase in temperature at the ATV  140 A causes an enlargement of the thermally expandable material  152  within the expandable element  150 . This causes the expandable element  150  to extend within the housing  148  as indicated by arrow  170 , forcing the rod  154  and valve disc  156  laterally away from the valve seat  160  and the gas flow outlet port  146 . When the arcuate surface  158  of the valve disc  156  no longer forms a seal against the valve seat  160 , a flow of cooling gas  30   Mod  flows from the gas flow inlet ports  144  through the gas flow outlet port  146  and into the downstream cooling passage  32  ( FIG. 8 ). The flow of cooling gas  30   Mod  increases as the valve disc  156  moves farther away from the valve seat  160  (e.g., in response to a further increase in temperature) as more flow area is provided between the arcuate surface  158  of the valve disc  156  and the valve seat  160 . 
         [0044]    The ATV  140 B is depicted in a closed configuration in  FIG. 13  and in an open configuration in  FIG. 14 . The ATV  140 B includes a valve section  242  including one or more gas flow inlet ports  244  and a gas flow outlet port  246 . The ATV  140 B further includes a housing  148  enclosing a bellows or other expandable element  150  containing a thermally expandable material  152 . The thermally expandable material  152  may include, for example, a silicon heat transfer fluid. Any other suitable thermally expandable material  152  that is stable at the operating temperatures of the turbine  16  (e.g., up to 1300° F.) may also be used. 
         [0045]    The expandable element  150  is coupled to a rod  154 . A valve disc  256  is provided at a distal end of the rod  154 . As depicted in  FIG. 13 , the valve disc  256  may have an outwardly directed arcuate surface  258 . Other suitable configurations of the valve disc  256  capable of providing the functionality described herein may also be used. 
         [0046]    The ATV  140 B is shown in a closed configuration in  FIG. 13 . In the closed configuration, the arcuate surface  258  of the valve disc  256  sealingly engages a corresponding circular valve seat  260  formed adjacent the gas flow outlet port  246 . In general, the valve disc  256  and valve seat  260  may have any suitable configuration capable of forming a seal to prevent the flow of gas through the gas flow outlet port  246 . In the closed configuration, the flow of cooling gas  30   Mod  is prevented from flowing from the gas flow inlet ports  244  through the gas flow outlet port  246  into the downstream cooling passage  32  ( FIG. 8 ). 
         [0047]    Referring now to  FIG. 14 , a decrease in temperature at the ATV  140 B causes a contraction of the thermally expandable material  152  within the expandable element  150 . This causes the expandable element  150  to contract within the housing  148  as indicated by arrow  172 , forcing the rod  154  and valve disc  156  laterally away from the valve seat  260  and the gas flow outlet port  246 . When the arcuate surface  258  of the valve disc  256  no longer forms a seal against the valve seat  260 , a flow of cooling gas  30   Mod  flows from the gas flow inlet ports  244  through the gas flow outlet port  246  and into the downstream cooling passage  32  ( FIG. 8 ). The flow of cooling gas  30   Mod  increases as the valve disc  256  moves farther away from the valve seat  260  (e.g., in response to a further decrease in temperature) as more flow area is provided between the arcuate surface  258  of the valve disc  256  and the valve seat  260 . 
         [0048]    According to embodiments, a passive auto pressure valve (APV) may be used in lieu of or in combination with the ATV valves  40 ,  140  described above. Such an APV is actuated by changes in pressure, rather than by changes in temperature. 
         [0049]    In various embodiments, components described as being “coupled” to one another can be joined along one or more interfaces. In some embodiments, these interfaces can include junctions between distinct components, and in other cases, these interfaces can include a solidly and/or integrally formed interconnection. That is, in some cases, components that are “coupled” to one another can be simultaneously formed to define a single continuous member. However, in other embodiments, these coupled components can be formed as separate members and be subsequently joined through known processes (e.g., fastening, ultrasonic welding, bonding). 
         [0050]    When an element or layer is referred to as being “on”, “engaged to”, “connected to” or “coupled to” another element, it may be directly on, engaged, connected or coupled to the other element, or intervening elements may be present. In contrast, when an element is referred to as being “directly on,” “directly engaged to”, “directly connected to” or “directly coupled to” another element, there may be no intervening elements or layers present. Other words used to describe the relationship between elements should be interpreted in a like fashion (e.g., “between” versus “directly between,” “adjacent” versus “directly adjacent,” etc.). As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items. 
         [0051]    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, elements, components, and/or groups thereof. 
         [0052]    This written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal languages of the claims.