Abstract:
One embodiment of the present invention is a unique gas turbine system having a system for modulating secondary air flow. Another embodiment is a compressor vane stage with a plenum employed in providing secondary air flow. Other embodiments include apparatuses, systems, devices, hardware, methods, and combinations for secondary air flow systems. Further embodiments, forms, features, aspects, benefits, and advantages of the present application shall become apparent from the description and figures provided herewith.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    The present application claims benefit of U.S. Provisional Patent Application No. 61/428,805, filed Dec. 30, 2010, entitled Gas Turbine Engine And System For Modulating Secondary Air Flow, which is incorporated herein by reference. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The present invention relates to gas turbine engines, and more particularly, to modulating secondary air flow in a gas turbine engine. 
       BACKGROUND 
       [0003]    Systems for controlling secondary air flow in a gas turbine engine remain an area of interest. Some existing systems have various shortcomings, drawbacks, and disadvantages relative to certain applications. Accordingly, there remains a need for further contributions in this area of technology. 
       SUMMARY 
       [0004]    One embodiment of the present invention is a unique gas turbine engine having a system for modulating secondary air flow. Another embodiment is a compressor vane stage with a plenum employed in providing secondary air flow. Other embodiments include apparatuses, systems, devices, hardware, methods, and combinations for secondary air flow systems. Further embodiments, forms, features, aspects, benefits, and advantages of the present application shall become apparent from the description and figures provided herewith. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0005]    The description herein makes reference to the accompanying drawings wherein like reference numerals refer to like parts throughout the several views, and wherein: 
           [0006]      FIG. 1  schematically illustrates some aspects of a non-limiting example of a gas turbine engine in accordance with an embodiment of the present invention. 
           [0007]      FIG. 2  schematically illustrates some aspects of a non-limiting example of a system for modulating secondary air flow in accordance with an embodiment of the present invention. 
           [0008]      FIG. 3  is a cross section depicting some aspects of a non-limiting example of an outlet guide vane and features of the system of  FIG. 2 . 
           [0009]      FIG. 4  is a cross section through a plenum illustrating some aspects of a non-limiting example of a stationary valve member in accordance with an embodiment of the present invention. 
           [0010]      FIGS. 5A and 5B  are cross sections through a plenum illustrating some aspects of a non-limiting example of potential operating points of a system for modulating secondary air flow in accordance with an embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0011]    For purposes of promoting an understanding of the principles of the invention, reference will now be made to the embodiments illustrated in the drawings, and specific language will be used to describe the same. It will nonetheless be understood that no limitation of the scope of the invention is intended by the illustration and description of certain embodiments of the invention. In addition, any alterations and/or modifications of the illustrated and/or described embodiment(s) are contemplated as being within the scope of the present invention. Further, any other applications of the principles of the invention, as illustrated and/or described herein, as would normally occur to one skilled in the art to which the invention pertains, are contemplated as being within the scope of the present invention. 
         [0012]    Referring to the drawings, and in particular,  FIG. 1 , some aspects of a non-limiting example of a gas turbine engine  10  in accordance with an embodiment of the present invention are schematically depicted. In one form, gas turbine engine  10  is an axial flow machine, e.g., an aircraft propulsion power plant. In other embodiments, gas turbine engine  10  may be a centrifugal flow machine or a combination axial centrifugal flow machine. It will be understood that the present invention is equally applicable to various gas turbine engine configurations, for example, including turbojet engines, turbofan engines, turboprop engines, turboshaft engines and combined cycle engine having axial, centrifugal and/or axi-centrifugal compressors and/or turbines. 
         [0013]    In the illustrated embodiment, gas turbine engine  10  includes an engine core  12 . Engine core  12  includes a compressor  14  having a plurality of blades and vanes  16  with outlet guide vanes (OGV)  18 , a diffuser  20 , a combustor  22 , a turbine  24  and a system  26  for modulating secondary air flow from compressor  14 , e.g., modulating the flow rate of the secondary air. Diffuser  20  and combustor  22  are fluidly disposed between OGV  18  of compressor  14  and turbine  24 . Turbine  24  is drivingly coupled to compressor  14  via a shaft  28 . Although only a single spool is depicted, it will be understood that the present invention is equally applicable to multi-spool engines. In various embodiments, gas turbine engine  10  may include, in addition to engine core  12 , one or more fans, additional compressors and/or additional turbines. 
         [0014]    During the operation of gas turbine engine  10 , air is supplied to the inlet of compressor  14 . Blades and vanes  16  compress air received at the inlet of compressor  14 , and after having been compressed, the air is discharged via OGV  18  into diffuser  20 . Diffuser  20  reduces the velocity of the pressurized air from compressor  14 , and directs the pressurized air to combustor  22 . Fuel is mixed with the air and combusted in combustor  22 , and the hot gases exiting combustor  22  are directed into turbine  24 . 
         [0015]    Turbine  24  includes a plurality of blades and vanes  30 . Blades and vanes  30  extract energy from the hot gases to, among other things, generate mechanical shaft power to drive compressor  14  via shaft  28 . In one form, the hot gases exiting turbine  24  are directed into a nozzle (not shown), which provides thrust output the gas turbine engine. In other embodiments, additional turbine stages in one or more additional rotors upstream and/or downstream of turbine  24  may be employed, e.g., in multi-spool gas turbine engines. 
         [0016]    Referring now to  FIGS. 2 and 3 , a non-limiting example of system  26  for modulating secondary air flow in accordance with an embodiment of the present invention is schematically depicted. Secondary air flow is a bleed air flow extracted from the main flowpath of a gas turbine engine. In some cases, the secondary airflow may be used one or more of cooling, thrust balance control, sump venting, seal cavity purging, and other conventional uses. In one form, system  26  modulates the flow of bleed air from OGV  18 . In a particular form, system  26  modulates the flow of bleed air from OGV  18  for use as cooling air that is delivered to one or more turbine blades and/or vanes of blades and vanes  30 . In other embodiments, system  26  may be configured to modulate bleed air from any one or more stages of compressor  14  in addition to or in place of OGV  18  for use as cooling air and/or for other purposes, including purposes not mentioned herein. 
         [0017]    System  26  includes a movable valve member  32 , a stationary valve member  34 , a valve shaft  36 , and an actuator  38  mounted outside of a compressor case  40 . It will be understood that in some embodiments, system  26  may include a plurality of movable valve members  32 , stationary valve members  34 , valve shafts  36 , and/or actuators  38 . In one form, movable valve member  32  and stationary valve member  34  are disposed in a distribution plenum  42 . In one form, plenum  42  collects the secondary airflow for delivery through movable valve member  32  and stationary valve member  34  to turbine  24  via passages (not shown) between system  26  and turbine  24 . In one form, plenum  42  is disposed inboard (inside) of the main flowpath  44 , which, in one form, extends through compressor  14  (including OGV  18 ), diffuser  20 , combustor  22  and turbine  24 . In other embodiments, plenum  42  may be disposed outside of main flowpath  44 . 
         [0018]    OGV  18  includes an outer band  46 , an inner band  48  and a plurality of airfoils disposed in main flowpath  44  between outer band  46  and inner band  48 . Inner band  48  includes a plurality of openings  52 , e.g., slots, which supply pressurized air from main flowpath  44  to plenum  42 . In one form, plenum  42  is integral with inner band  48 . In other embodiments plenum  42  may be separately formed and may be in fluid communication with main flowpath  44  via openings  52  and/or other means. In one form, valve shaft  36  is received in an airfoil  50  of the plurality of airfoils of OGV  18 . 
         [0019]    Movable valve member  32  includes two inlet ports  54 , a passage  56  and a discharge port  58 . Passage  56  is in fluid communication with ports  54  and port  58 . Movable valve member  32  is operative to transmit secondary air flow through passage  56  between ports  54  and port  58 . Movable valve member  32  is coupled to valve shaft  36 . In one form, movable valve member  32  extends from valve shaft  36 . In one form, movable valve member  32  is a part of valve shaft  36 . In other embodiments, valve member  32  may be a separate component that is otherwise coupled to valve shaft  36 . 
         [0020]    Referring now to  FIG. 4  in conjunction with  FIGS. 2 and 3 , the present non-limiting example of an embodiment of the present invention is further described.  FIG. 4  depicts a partial cross section through plenum  42  that illustrates walls  60 . Walls  60  define the extents of plenum  42  in the engine axial direction. In the depiction of  FIG. 4 , movable valve member  32  is removed for purposes of clarity of illustration. In one form, stationary valve member  34  is disposed in and integral with plenum  42 , although in other embodiments, stationary valve member  34  may be a separate component. In still other embodiments, stationary valve member  34  may not be disposed in or integral with plenum  42 . Stationary valve member  34  is structured to interact with movable valve member  32  in order to yield a valve for modulating the flow of secondary air. In one form, stationary valve member  34  is structured receive at least partially therein movable valve member  32 . In other embodiments, other mechanical arrangements and types of interface between stationary valve member  34  and movable valve member  32  than that illustrated and described herein may be employed. 
         [0021]    Stationary valve member  34  includes a plurality of walls  62 . In one form, walls  62  are integral with and adjoin walls  60 . Walls  62  have ends  64 A- 64 D, in between of which movable valve member  32  is received. Movable valve member  32  is also received into an opening  66  in a bottom wall  68  of plenum  42 . In one form, two gate openings  70  are located between the ends of walls  62 ; one between ends  64 A and  64 B, and another between ends  64 C and  64 D. Gate openings  70  are disposed inboard of both compressor case  40  and flowpath  44 . Gate openings  70  are in fluid communication with plenum  42 , and hence exposed to the pressurized air in plenum  42  that is supplied to plenum  42  from main flowpath  44  via openings  52 . Movable valve member  32  and stationary valve member  34  are geometrically structured such that a movement of movable valve member  32  yields an overlap of ports  54  with gate openings  70 . This overlap forms a valve flow area that permits the secondary air flow to pass through gate opening  70  and ports  54  and discharge through port  58 . 
         [0022]    Valve shaft  36  extends between actuator  38  and movable valve member  32 . In one form, valve shaft  36  is a single integral shaft. In other embodiments, valve shaft  36  may be formed of two or more components coupled or joined together. In one form, valve shaft  36  is oriented with its major axis  72  being perpendicular to the centerline of engine  10 . In other embodiments, valve shaft  36  may extend at other angles relative to the centerline of engine  10 . Valve shaft  36  is operative to transmit motion from actuator  38  to movable valve member  32 . In one form, the motion is a rotation of valve shaft  36  about axis  72  relative to stationary valve member  34 . In another form, the motion is a translation of valve shaft  36  along axis  72 . In other embodiments, both rotation and translation may be employed. In one form, valve shaft  36  extends in one direction through an airfoil  50  of OGV  18  toward plenum  42 , and extends in the other direction outside of main flowpath  44  toward compressor case  40 . In a particular form, valve shaft  36  extends from outside of compressor case  40  to inside of flowpath  44 . In other embodiments, valve shaft  36  may be arranged otherwise, for example and without limitation, and may extend from inside of compressor case  40  to inside of flowpath  44 . 
         [0023]    Actuator  38  is coupled to valve shaft  36 . Actuator  38  is operative to impart motion to valve shaft  36  to control the size of the valve flow area in order to modulate secondary air flow. In one form, actuator  38  is a rotary actuator. In another form, actuator  38  is a linear actuator. In other embodiments, actuator  38  may provide both rotational and translational output. In one form, actuator  38  is a mechanical actuator. In another form, actuator  38  is an electrical actuator. In various embodiments, actuator  38  may operate using a pressure differential, e.g., of air, hydraulic fluid, engine lubricating oil or fuel, or may be actuated via an electric motor or via any convenient means. In one form, actuator  38  is positioned outside of compressor case  40 , which allows easy access to actuator  38  and valve shaft  36  for maintenance/repair/replacement, e.g., relative to actuators located inside an engine case such as compressor case  40 . In other embodiments, actuator  38  may be positioned in other locations, including inside compressor case  40 . 
         [0024]    Motion imparted by actuator  38  is transmitted through valve shaft  36  to movable valve member  32 , which varies the overlap of ports  54  with gate openings  70 . The overlap of ports  54  with gates openings  70  provides a valve flow area for discharging pressurized air from plenum  42 . Although the present embodiment employs two ports  54  with two gate openings  70  to create the valve flow area, it will be understood that a greater or lesser number of ports and/or gates may alternatively be employed. When movable valve member  32  is positioned by actuator  38  to cause an overlap between ports  54  and gate openings  70 , pressurized air in plenum  42  flows through gate openings  70  into ports  54 , which is discharged from port  58  via passage  56  of movable valve member  32 . When movable valve member  32  is positioned by actuator  38  to prevent an overlap between ports  54  and gate openings  70 , the flow of pressurized air from plenum  42  is prevented, other than any leakage. Excessive leakage may be controlled, if desired, by the use of seals (not shown). 
         [0025]    In one form, ports  54  and gate openings  70  are positioned on movable valve member  32  and stationary valve member  34 , respectively, to provide a desired valve flow area that may be changed by a rotation of movable valve member  32 , e.g., about axis  72 . In other embodiments, ports  54  and gate openings  70  may be positioned to provide a desired valve flow area based on other types of motion. For example, ports  54  and gate openings  70  may be positioned on movable valve member  32  and stationary valve member  34 , respectively, to provide a desired valve flow area that may be changed by a translation of movable valve member  32 , e.g., along axis  72 , relative to stationary valve member  34 . It will be understood that the placement of ports  54  and gate openings  70 , as well as other aspects of the designs of movable valve member  32  and stationary valve member  34  may take into account various parameters associated with the operation of engine  10 , such as thermal expansion, and pressure and mechanical load deflections that may affect the position of ports  54  relative to gate openings  70 . 
         [0026]    In one form, the overlap between ports  54  and gate openings  70  may be changed from zero to the maximum allowable overlap permitted by the sizes of ports  54  and gate openings  70 . In other embodiments, operation may be limited to some minimum nonzero overlap and some upper limit that is less than the maximum allowable overlap permitted by the sizes of ports  54  and gate openings  70 . In some embodiments, the overlap between ports  54  and gate openings  70  may be varied incrementally, whereas in others, it may be varied continuously, e.g., as between some minimum and maximum values. Embodiments employing incremental variation in the overlap may include only two valve positions, e.g., opened/closed or minimum/maximum, or may include more than two valve positions. 
         [0027]    Referring now to  FIGS. 5A and 5B , system  26  is depicted with no overlap between ports  54  and gate openings  70  ( FIG. 5A ) and with a maximum overlap between ports  54  and gate openings  70  ( FIG. 5B ). In the depiction of  FIG. 5A , secondary airflow is inhibited because movable valve member  32  inhibits the flow of pressurized air in plenum  42  from entering passage  56  and discharging through port  58 . In the depiction of  FIG. 5B , movable valve member  32  is depicted as having been rotated sufficiently to fully overlap gate openings  70 , thereby allowing secondary air flow to enter passage  56  via gate openings  70  and ports  54 , which is discharged at port  58  of movable valve member  32 . It will be understood that the relative sizes of ports  54  and gate openings  70 , as well as the sizes of other features set forth herein, are merely illustrative and are non-limiting. Rather, the design parameters for system  26  are selected in accordance with the needs of the particular application. 
         [0028]    Embodiments of the present invention include a gas turbine engine, comprising: a compressor; a combustor in fluid communication with the compressor; a turbine in fluid communication with the compressor; and a system for modulating secondary air flow from the compressor, including: a valve shaft; a movable valve member having a first port, a second port and a passage in fluid communication with the first port and the second port, wherein the movable valve member is coupled to the valve shaft and is operative to transmit the secondary air flow through the passage between the first port and the second port; and a stationary valve member having a gate opening positioned adjacent to the first port, wherein the movable valve member and the stationary valve member are structured to yield an overlap of the first port with the gate opening upon a movement of the movable valve member; and wherein the overlap forms a valve flow area that permits the secondary air flow to pass through the gate opening and the first port for discharge through the second port. 
         [0029]    In a refinement, the gas turbine engine further includes a main flowpath extending from the compressor to the turbine, wherein the valve shaft is disposed at least partially outside of the main flowpath; and wherein the gate opening is disposed inboard of the main flowpath. 
         [0030]    In an additional refinement, the gas turbine engine further includes an engine case and an actuator, wherein the actuator is coupled to the valve shaft and is operative to impart the movement to the valve shaft effective to control the size of the valve flow area, and wherein the actuator is positioned outside of an engine case. 
         [0031]    In another refinement, the gate opening is disposed inboard of the engine case. 
         [0032]    In yet another refinement, the gas turbine engine further includes a main flowpath extending from the compressor to the turbine, wherein the gate opening is disposed inboard of the main flowpath. 
         [0033]    In still another refinement, the movement is a rotation of the valve shaft. 
         [0034]    In yet still another refinement, the compressor includes a vane stage having a plurality of airfoils, and wherein at least one of the valve shaft and the movable valve member are disposed at least partially in an airfoil of the plurality of airfoils. 
         [0035]    In a further refinement, the compressor includes a vane stage having a plenum in fluid communication with the valve flow area. 
         [0036]    In yet a further refinement, the gas turbine engine further a main flowpath extending from the compressor to the turbine, wherein the vane stage includes an opening in fluid communication with both the main flowpath and the plenum. 
         [0037]    In still a further refinement, the plenum is disposed inboard of the main flowpath. 
         [0038]    Embodiments of the present invention include a gas turbine engine, comprising: a compressor having a compressor case; a combustor in fluid communication with the compressor; a turbine in fluid communication with the compressor; and a system for modulating secondary air flow from the compressor, including: means for providing a valve flow area that permits secondary air flow from the compressor, wherein the means for providing is located inboard of the compressor case; and means for mechanically actuating the means for providing, wherein the means for mechanically actuating is disposed at least partially outside the compressor case. 
         [0039]    In a refinement, the gas turbine engine further includes means for collecting the secondary air flow that passes through the valve flow area. 
         [0040]    In another refinement, the means for collecting is disposed inboard of a main flowpath of the gas turbine engine. 
         [0041]    In yet another refinement, the means for providing includes a rotatable valve member. 
         [0042]    Embodiments of the present invention include a vane stage for a gas turbine engine, comprising: an inner band; an outer band; a plurality of airfoils disposed between the inner band and the outer band; and a plenum operative to distribute secondary air flow, wherein the plenum employs a stationary valve member adapted to interface with a movable valve member having a port, wherein the stationary valve member includes a gate opening positioned adjacent to the port, and wherein an overlap of the port with the gate opening forms a valve flow area that permits the secondary air flow to pass through the gate opening and the port. 
         [0043]    In a refinement, the plenum has an opening structured to receive at least one of a valve shaft and the movable valve member. 
         [0044]    In another refinement, the plenum has another opening structured to receive at least one of the valve shaft and the movable valve member. 
         [0045]    In yet another refinement, at least one of the inner band and the outer band include openings in fluid communication with a main flowpath of the gas turbine engine and in fluid communication with the plenum. 
         [0046]    In still another refinement, at least one of the airfoils is adapted to receive at least one of a valve shaft coupled to the movable valve member and the movable valve member. 
         [0047]    In yet still another refinement, the plenum is located inboard of a main flowpath of the gas turbine engine. 
         [0048]    While the invention has been described in connection with what is presently considered to be the most practical and preferred embodiment, it is to be understood that the invention is not to be limited to the disclosed embodiment(s), but on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims, which scope is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures as permitted under the law. Furthermore it should be understood that while the use of the word preferable, preferably, or preferred in the description above indicates that feature so described may be more desirable, it nonetheless may not be necessary and any embodiment lacking the same may be contemplated as within the scope of the invention, that scope being defined by the claims that follow. In reading the claims it is intended that when words such as “a,” “an,” “at least one” and “at least a portion” are used, there is no intention to limit the claim to only one item unless specifically stated to the contrary in the claim. Further, when the language “at least a portion” and/or “a portion” is used the item may include a portion and/or the entire item unless specifically stated to the contrary.