Abstract:
A stator for a gas turbine engine includes a stator vane, a first cooling passage located at the stator to provide a cooling fluid flow to a first portion of the stator, and a second cooling passage located at the stator to provide a cooling fluid flow to a second portion of the stator. A connection passage extends at least partially through the stator to connect a first cooling passage inlet of the first cooling passage to a second cooling passage inlet of the second cooling passage. The cooling fluid flow is directed from a common cooling flow source into the first cooling passage and the second cooling passage via the first cooling passage inlet.

Description:
BACKGROUND 
       [0001]    This disclosure relates to gas turbine engines, and more particularly to the provision of cooling air for components of gas turbine engines. 
         [0002]    Gas turbines hot section components, in particular turbine vanes and blades in the turbine section of the gas turbine are configured for use within particular temperature ranges. Such components often rely on cooling airflow to maintain turbine components within this particular temperature range. For example, stationary turbine vanes often have internal passages for cooling airflow to flow through, and additionally may have openings in an outer surface of the vane for cooling airflow to exit the interior of the vane structure and form a cooling film of air over the outer surface to provide the necessary thermal conditioning. Other components of the turbine often also require such thermal conditioning to reduce thermal gradients that would otherwise be present in the structure and which are generally undesirable. Thus, ways to increase thermal conditioning capability in the turbine are desired. 
         [0003]    The internal cooling passages are typically formed in stator vanes through the use of ceramic cores during the casting process of the stator vanes. The complex geometry of the cooling passages typically prevents advantageously combining ceramic cores into a single core, which would significantly improve producibility of the stator vane. Further, as separate cores are utilized, cooling air flowed through the cooling passages is therefore fed from separate cooling airflow sources, which in many instances may not be optimal cooling air sources. 
       SUMMARY 
       [0004]    In one embodiment, a stator for a gas turbine engine includes a vane, a first cooling passage located at the stator to provide a cooling fluid flow to a first portion of the stator, and a second cooling passage located at the stator to provide a cooling fluid flow to a second portion of the stator. A connection passage extends at least partially through the stator to connect a first cooling passage inlet of the first cooling passage to a second cooling passage inlet of the second cooling passage. The cooling fluid flow is directed from a common cooling flow source into the first cooling passage and the second cooling passage via the first cooling passage inlet. 
         [0005]    Additionally or alternatively, in this or other embodiments the first cooling passage is a vane leading edge cooling passage of the vane, and the second cooling passage is a platform cooling passage located at a stator platform. 
         [0006]    Additionally or alternatively, in this or other embodiments the connection passage includes a passage opening in an external surface of the stator, and a closure secured over the passage opening to prevent leakage of the cooling fluid flow through the passage opening. 
         [0007]    Additionally or alternatively, in this or other embodiments the closure is one of a plug or a cover. 
         [0008]    Additionally or alternatively, in this or other embodiments the closure is secured over the passage opening via welding or brazing. 
         [0009]    Additionally or alternatively, in this or other embodiments the first cooling passage inlet extends radially outwardly to a greater extent than the second cooling passage inlet. 
         [0010]    In another embodiment, a turbine of a gas turbine engine includes a turbine rotor, and a turbine stator including a vane, a first cooling passage located at the turbine stator to provide a cooling fluid flow to a first portion of the turbine stator and a second cooling passage located at the turbine stator to provide a cooling fluid flow to a second portion of the turbine stator. A connection passage extends at least partially through the turbine stator to connect a first cooling passage inlet of the first cooling passage to a second cooling passage inlet of the second cooling passage. The cooling fluid flow is directed from a common cooling fluid source into the first cooling passage and the second cooling passage via the first cooling passage inlet. 
         [0011]    Additionally or alternatively, in this or other embodiments the first cooling passage is a vane leading edge cooling passage of the vane, and the second cooling passage is a platform cooling passage located at a stator platform. 
         [0012]    Additionally or alternatively, in this or other embodiments the turbine stator includes a closure located at an external surface of the turbine stator to prevent leakage of the cooling fluid flow from the connection passage. 
         [0013]    Additionally or alternatively, in this or other embodiments the closure is one of a plug or a cover. 
         [0014]    Additionally or alternatively, in this or other embodiments the closure is secured at the external surface via welding or brazing. 
         [0015]    Additionally or alternatively, in this or other embodiments the first cooling passage inlet extends radially outwardly to a greater extent than the second cooling passage inlet. 
         [0016]    In yet another embodiment, a method of cooling a stator for a gas turbine engine includes forming a first cooling passage in a stator, forming a second cooling passage in the stator separate from the first cooling passage, forming a connection passage in the stator to connect a first cooling passage inlet of the first cooling passage to a second cooling passage inlet of the second cooling passage, and connecting the first cooling passage inlet to a cooling flow source. 
         [0017]    Additionally or alternatively, in this or other embodiments a cooling flow is directed from the cooling flow source through the first cooling passage inlet and a first portion of the cooling flow is directed from the first cooling passage inlet through the connecting passage to the second cooling passage. 
         [0018]    Additionally or alternatively, in this or other embodiments the first portion of the cooling flow is directed into the second cooling passage and a second portion of the cooling flow is directed into the first cooling passage. 
         [0019]    Additionally or alternatively, in this or other embodiments forming of the connection passage includes drilling the connection passage from an external surface of the stator through one of the first cooling passage inlet or the second cooling passage inlet and into the other of the first cooling passage inlet or the second cooling passage inlet. 
         [0020]    Additionally or alternatively, in this or other embodiments a closure is secured at an opening formed at the external surface. 
         [0021]    Additionally or alternatively, in this or other embodiments the closure is one of a plug or a cover. 
         [0022]    Additionally or alternatively, in this or other embodiments the first cooling passage is a vane leading edge cooling passage of the stator and the second cooling passage is a platform cooling passage disposed at a stator platform. 
         [0023]    Additionally or alternatively, in this or other embodiments one of the first cooling passage inlet or the second cooling inlet passage extends radially outwardly to a greater extent than the other of the first cooling passage inlet or the second cooling passage inlet. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0024]    The subject matter which is regarded as the present 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 present disclosure are apparent from the following detailed description taken in conjunction with the accompanying drawings in which: 
           [0025]      FIG. 1  illustrates a schematic cross-sectional view of an embodiment of a gas turbine engine; 
           [0026]      FIG. 2  illustrates a schematic cross-sectional view of an embodiment of a turbine section of a gas turbine engine; and 
           [0027]      FIG. 3  is a schematic view of an embodiment of a cooling flow passage arrangement for a stator vane; 
           [0028]      FIG. 4  is a schematic view of an embodiment of a connection passage for a cooling flow passage arrangement; and 
           [0029]      FIG. 5  is another schematic view of an embodiment of a connection passage for a cooling flow passage arrangement. 
       
    
    
     DETAILED DESCRIPTION 
       [0030]      FIG. 1  is a schematic illustration of a gas turbine engine  10 . The gas turbine engine generally has includes fan section  12 , a low pressure compressor  14 , a high pressure compressor  16 , a combustor  18 , a high pressure turbine  20  and a low pressure turbine  22 . The gas turbine engine  10  is circumferentially disposed about an engine centerline X. During operation, air is pulled into the gas turbine engine  10  by the fan section  12 , pressurized by the compressors  14 ,  16 , mixed with fuel and burned in the combustor  18 . Hot combustion gases generated within the combustor  18  flow through high and low pressure turbines  20 ,  22 , which extract energy from the hot combustion gases. 
         [0031]    In a two-spool configuration, the high pressure turbine  20  utilizes the extracted energy from the hot combustion gases to power the high pressure compressor  16  through a high speed shaft  24 , and the low pressure turbine  22  utilizes the energy extracted from the hot combustion gases to power the low pressure compressor  14  and the fan section  12  through a low speed shaft  26 . The present disclosure, however, is not limited to the two-spool configuration described and may be utilized with other configurations, such as single-spool or three-spool configurations, or gear-driven fan configurations. 
         [0032]    Gas turbine engine  10  is in the form of a high bypass ratio turbine engine mounted within a nacelle or fan casing  28  which surrounds an engine casing  30  housing an engine core  32 . A significant amount of air pressurized by the fan section  12  bypasses the engine core  32  for the generation of propulsive thrust. The airflow entering the fan section  12  may bypass the engine core  32  via a fan bypass passage  34  extending between the fan casing  28  and the engine casing  30  for receiving and communicating a discharge flow F 1 . The high bypass flow arrangement provides a significant amount of thrust for powering an aircraft. 
         [0033]    The engine casing  30  generally includes an inlet case  36 , a low pressure compressor case  38 , and an intermediate case  40 . The inlet case  36  guides air to the low pressure compressor case  38 , and via a splitter  42  also directs air through the fan bypass passage  34 . 
         [0034]    Referring now to  FIG. 2 , the high pressure turbine  20  includes one or more high pressure turbine rotors  44  in an axially-alternating arrangement with one or more high pressure turbine (HPT) stators  46 . Similarly, the low pressure turbine  24  includes one or more low pressure turbine rotors in an axially-alternating arrangement with one or more low pressure turbine stators. The following description is in reference to a high pressure turbine stator  46 , but one skilled in the art will readily appreciate that the disclosure provided herein may be similarly utilized in a low pressure turbine stator, or similar turbine compressor components having internal cooling passages. The HPT stator  46  includes a turbine vane  52  and an outer platform  54  located at a radially outboard extent of the turbine vane  52 , and an inner platform  56  located at a radially inboard extent of the turbine vane  52 . 
         [0035]    Referring now to  FIG. 3 , because of high operating temperatures in this portion of the gas turbine engine  10 , the HPT stator  46  is provided with cooling passages to distribute cooling airflow internally throughout the HPT stator  46 . In some embodiments, the cooling passages circulate the cooling airflow in an interior of the HPT stator  46 , while in other embodiments the cooling passages communicate with film cooling holes (not shown) on the HPT stator  46  to form a cooling film one or more external surfaces of the HPT stator  46 . 
         [0036]    In the embodiment of  FIG. 3 , at least two cooling passages are formed in the HPT stator  46 , a vane leading edge cooling passage  58  extending along a vane leading edge  60 , and a platform cooling passage  62  extending along the outer platform  54 . The platform cooling passage  62  has a platform cooling inlet  64 , while the vane leading edge cooling passage  58  has a leading edge cooling inlet  66 . Due to the complexity of the cooling passage geometry, the vane leading edge cooling passage  58  is formed separately from the platform cooling passage  62 , and the platform cooling inlet  64  is separate from the leading edge cooling inlet  66 . 
         [0037]    Referring now to  FIG. 4 , it is desired to feed the cooling airflow to the platform cooling inlet  64  and the leading edge cooling inlet  66  from a common cooling flow source  68 . For example, in some embodiments, it is desired to locate the cooling flow source  68  at a radially outboardmost practicable location, where the cooling airflow has a relatively low temperature and high pressure, relative to radially inboard locations. To feed the platform cooling inlet  64  and the leading edge cooling inlet  66  from the common cooling flow source  68 , a communication passage  70  is formed in the HPT stator  46 . The communication passage  70  extends, in this embodiment, between the leading edge cooling inlet  66  and the platform cooling inlet  64  with the leading edge cooling inlet  66  connected to the common cooling flow source  68 . 
         [0038]    In some embodiments, the connection passage  70  is formed in the HPT stator  46  by drilling. The connection passage  70  is drilled by, for example, drilling through an external surface  72  of the HPT stator  46  at the platform cooling inlet  64 . The connection passage  70  is drilled from the external surface  72 , through the platform cooling inlet  64  and into the leading edge cooling inlet  66 . It is to be appreciated that the forming of the connection passage  70  described herein is merely exemplary, one skilled in the art will readily appreciate that other methods may be utilized to form the connection passage  70 . In some embodiments, the connection passage  70  extends between the platform cooling inlet  64  and the leading edge cooling inlet  66  in a circumferential direction. 
         [0039]    Referring now to  FIG. 5 , once the connection passage  70  is formed, an external surface opening  74  must be closed to prevent leakage of the cooling airflow. The external surface opening may be closed via a closure, such as a plug  76  that is secured in place in the external surface opening  74  by, for example, welding or brazing. Other means may also be used to close the external surface opening  74 , such as a sheet metal cover secured over external surface opening  74  may be utilized. 
         [0040]    Utilizing the connection passage  70  allows for a HPT stator  46  casting with improved producibility, while utilizing a selected cooling flow source  68  that improves gas turbine engine  10  efficiency and durability. 
         [0041]    While the present disclosure has been described in detail in connection with only a limited number of embodiments, it should be readily understood that the present disclosure is not limited to such disclosed embodiments. Rather, the present disclosure can be modified to incorporate any number of variations, alterations, substitutions or equivalent arrangements not heretofore described, but which are commensurate with the scope of the present disclosure. Additionally, while various embodiments of the present disclosure have been described, it is to be understood that aspects of the present disclosure may include only some of the described embodiments. Accordingly, the present disclosure is not to be seen as limited by the foregoing description, but is only limited by the scope of the appended claims.