Abstract:
A gas turbine engine includes a combustor having a combustor tile assembly with improved cooling air flow channels and enhanced cooling efficiency. A method of manufacturing same is provided which increases production capabilities and the geometric configurations of the exit ports which in turn improve the hot side operating temperature of the tiles in the combustion chamber.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a non-provisional application claiming priority to U.S. Provisional Application No. 62/186,651 filed Jun. 30, 2015, which is hereby incorporated by reference in its entirety. 
     
    
     FIELD OF TECHNOLOGY 
       [0002]    A gas turbine engine uses a combustor and a combustor liner, and more particularly, a liner and method of manufacturing wherein wall elements form an improved cooling system. 
       BACKGROUND 
       [0003]    Gas turbine engines are used extensively in high performance aircraft and they employ fans, compressors, combustors and turbines and during operation they generate energies and air flows that impact the performance of the engine&#39;s systems. A gas turbine may employ one or more combustors that serve as the fuel preparation and ignition chambers for generating the temperature rise which is required to drive the turbine blades. Typical combustors may use inner and outer liners that define an annular combustion chamber in which the fuel and air mixtures are combusted. The inner and outer liners are radially offset from the combustor casings such that inner and outer passage ways are defined between the respective inner and outer liners and casings. 
         [0004]    In order to improve the thrust and fuel consumption of gas turbine engines, i.e., the thermal efficiency, it is necessary to use high compressor exit pressures and combustion exit temperatures. Higher compressor pressures also give rise to higher compressor exit temperatures supplied to the combustion chamber, which results in a combustor chamber experiencing much higher temperatures than are present in most conventional combustor designs. 
         [0005]    A need exists to provide effective cooling of the combustion chamber walls. Various cooling methods have been proposed including the provision of a doubled walled combustion chamber whereby cooling air is directed into a gap between spaced outer and inner walls, thus cooling the inner wall. This air is then exhausted into the combustion chamber through apertures in the inner wall. The inner wall may be comprised of a number of heat resistant tiles. 
         [0006]    Combustion chamber walls which comprise two or more layers are advantageous in that they only require a relatively small flow of air to achieve adequate wall cooling. However, hot spots may form in certain areas of the combustion chamber wall. This problem is heightened as temperatures within the combustion chamber which can exceed 3,500 degrees F. Such harsh environmental conditions may prematurely reduce the life of the liner of the combustor. In addition, loss of tile attachment and subsequent component distress remains an engineering challenge in current combustor technology. 
         [0007]    Providing enhanced air cooling flow could help minimize hot spots and the overall performance of the combustor. Accordingly, it would be helpful to provide an improved combustor tile system and method of manufacturing same. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0008]    While the claims are not limited to a specific illustration, an appreciation of the various aspects is best gained through a discussion of various examples thereof. Referring now to the drawings, exemplary illustrations are shown in detail. Although the drawings represent the illustrations, the drawings are not necessarily to scale and certain features may be exaggerated to better illustrate and explain an innovative aspect of an example. Further, the exemplary illustrations described herein are not intended to be exhaustive or otherwise limiting or restricted to the precise form and configuration shown in the drawings and disclosed in the following detailed description. Exemplary illustrations are described in detail by referring to the drawings as follows: 
           [0009]      FIG. 1  illustrates a schematic diagram of a gas turbine engine employing an improved combustor tile assembly; 
           [0010]      FIG. 2  illustrates a side sectional view of a gas turbine engine with an improved tiled combustor assembly; 
           [0011]      FIG. 3  illustrates a perspective view of a shell of a combustor having a tiled combustor assembly; 
           [0012]      FIG. 4  illustrates a partial perspective view of the layers of one tile that is shown in the combustor assembly of  FIG. 3 ; 
           [0013]      FIG. 5  illustrates an enlarged perspective view taken from circle  5  of  FIG. 4 , showing the layers of the tile; 
           [0014]      FIG. 6  illustrates an enlarged side view of a portion of the  FIG. 4  tile, showing a flow path through the hot side of the tile; 
           [0015]      FIG. 7  illustrates a top view of the exit port of the flow path that is shown in  FIG. 6 ; 
           [0016]      FIG. 8  illustrates a side sectional view of an alternative tile assembly showing the flow path of air over the hot surface of the combustor tile; 
           [0017]      FIG. 9  illustrates an enlarged side view of a portion of the  FIG. 8  tile, showing a flow path through the hot side of the tile; and 
           [0018]      FIG. 10  illustrates a top view of the exit port of the flow path that is shown in the  FIG. 9  tile assembly. 
       
    
    
     DETAILED DESCRIPTION 
       [0019]    A gas turbine engine combustor tile design includes an exemplary high temperature capable dual wall combustor tile attached to a lower temperature capable cold skin of a combustor liner. The wall cooling is accomplished by feeding cooling air through holes in the cold skin. The cooling air impinges on the back side of the hot tile and then flows out ejection slots or holes into the combustor flow path. The trajectory of the cooling air out of the ejection slots impacts film cooling effectiveness. An improved ejection slot angle trajectory and exit opening is provided which permits reattachment of the exited cooled air to the hot surface of the tile. The shape of the exit hole of the ejection slot may be modified to various shapes to decrease the velocity of the air exiting the ejection slots, thus enhancing film cooling effectiveness. 
         [0020]    An exemplary method of manufacturing a combustor is provided which results in increased film cooling effectiveness. Such method of manufacture includes machining ejection slots in the hot skin side of the tile that are not normal to the centerline of the combustor. Methods could also include shaping holes through machining processes that provide ejection slot exit hole configurations that are, for example, fanned shaped, conical shaped, partial conical shapes, and other geometric configurations. One exemplary style of manufacturing could employ DLD (direct laser deposition) processes for generating these unique configurations. Said shapes can be manufactured in a single manufacturing process where the ejection slot and exit port configuration are generated. 
         [0021]      FIG. 1  illustrates a gas turbine engine  10 , which includes a fan  12 , a low pressure compressor and a high pressure compressor,  14  and  16 , a combustor  18 , and a high pressure turbine, intermediate pressure, and low pressure turbine,  20  thru  22 , respectively. The high pressure compressor  16  is connected to a first rotor shaft  24 , the low pressure compressor  14  is connected to a second rotor shaft  26 , and the fan  12  is connected to a third rotor shaft  43 . The shafts extend axially and are parallel to a longitudinal center line axis  28 . It will be appreciated that the improvements disclosed herein can be used with gas turbine engines that incorporate a single or two-shaft architecture. 
         [0022]    Ambient air  30  enters the fan  12  and is directed across a fan rotor  32  in an annular duct  34 , which in part is circumscribed by fan case  36 . The bypass airflow  38  provides engine thrust while the primary gas stream  40  is directed to the compressors  14  and  16 , combustor  18 , and the turbines  20  thru  22 . Thus airflow of the gas stream  40  traverses fore to aft through the compressors and in to the combustor  18 . The gas turbine engine  10  includes an improved combustor  18  having a tile system or assembly  42 , the details of the exemplary design are set forth herein. An improved method of manufacturing the assembly  42  is also contemplated. 
         [0023]      FIG. 2  illustrates a side sectional view of the combustor  18  with a plurality of tile assemblies  42  that are secured to a cold skin or outer surface of a liner  44 . A combustor outer case  46  circumscribes a combustor shell  48  and a fuel nozzle  50  provides pressurized fuel  52  to a combustor chamber  54 . The combusted fuel may be ignited by an igniter (not shown) which in turn subjects the chamber  54  to elevated temperatures which can exceed 3,500 degrees F. Such arrangement causes extreme temperatures to impinge upon the hot surface  56  of each tile assembly  42 . A fastener  60  or other mechanism secures each tile assembly  42  to the liner  44  of the combustor  18 . It will be appreciated that an alternative attachment mechanism may be employed to secure the tiles to the liner  44 . The tile assembly  42  is serviceable and may be replaced when it is damaged or is otherwise sufficiently depleted in performance quality. 
         [0024]      FIG. 3  illustrates the shell  48  of the combustor  18  having a plurality of tile assemblies  42  spaced apart and secured to the inner surface  58  of the skin  44 . The inner surface  58  is protected by the tile assembly  42  at substantially the entire inner surface  58  of the skin  44 . A gap  60  is maintained between the inner surface  58  and the assembly  42 . The cooling effectiveness of each dual wall tile assembly  42  does not rely on accurately maintaining the gap  60  between the tile standoff features and the cold skin  44 , as is the case for conventional tiles. The tile attachment feature or fastener  60  will be maintained at a lower temperature as compared to a conventional tile system. This arrangement results in a robust mechanical attachment that resists creep and loss of preload, both of which translate into improved component reliability/durability and reduced parasitic leakage. Parasitic leakage which bypasses the cooling circuit translates into lower overall cooling effectiveness. 
         [0025]    Reduced combustor wall cooling translates into a competitive advantage in term of combustor pattern factor control, radial temperature profile control, efficiency, and emissions reduction. The integral dual wall metallic combustor tile assembly  42  offers significant advantages over conventional tiles including but not limited to a reduction in wall cooling flow, a cooler tile attachment (improved reliability/durability), reduced tile leakage and the associated penalty in cooling effectiveness due to leakage, and a more robust mechanical design in terms of less sensitivity to cold skin and tile geometric tolerances/operating deflections. 
         [0026]      FIG. 4  illustrates a perspective view of one portion of a tile assembly  42  that is shown in  FIG. 3 . Here the tile assembly  42  includes a cold skin  62  and a hot skin  64  that may be manufactured from CMC or metal or a combination of these materials. The skins are spaced apart from one another by an air gap  66  that extends axially and is sandwiched between the cold skin  62  and the hot skin  64 . The air gap  66  provides an airflow path  68  for passing cooled fluid such as air through the tile assembly  42  and into the combustor chamber  54 . 
         [0027]    The cold skin  62  includes a plurality of normally extending inlet ports  70  that are spaced apart from one another and they extend along the axial length of each tile in the combustor  18 . The number of inlet ports  70  may be based on the desired air flow volume considerations that may be appropriate for the demands of the engine  10 . The ports  70  are oriented substantially normal to the bottom surface  72  of the cold skin  62 . In the section cut that is show in  FIG. 4 , the inlet ports  70  have been arranged such that they are offset in the axial direction, see arrow  74 , as well as in the circumferential direction, see arrow  76 . 
         [0028]    The hot skin  64  includes a number of angled effusion cooling holes  78  that extend through the hot skin starting from a lower surface  80  of the hot skin  64  to a top surface  82  of the hot skin  64 . Each such cooling hole  78  is oriented along or nearly along a centerline CL that is positioned at an angle φ relative to the lower surface  80  of the hot skin  64 . It will be appreciated that the angle φ may be in the range of 30 degrees, however it could be more or less. An exit hole  84  of each cooling hole  78  is configured to have a unique shape so as to enhance air flow  68  as it traverses out of the cooling hole  78 . By realigning the air flow  68  along a path that is closer to the top surface  84  of the hot skin  64 , improved cooling can be obtained which results in increased tile and combustor performance. This in turn improves the efficiency of the engine  10 . 
         [0029]    With continued reference to  FIG. 4 , the exit holes  84  are stacked along and arranged axially  74  in rows along the tiles&#39; surface  82 . As an example, a first row  86  is shown having a plurality of exit holes  84  that extend axially (in the direction of arrow  74 ). In addition, a second row  88  is shown having a plurality of exit holes  84  that extend axially (in the direction of arrow  74 ). Each such row  86 ,  88  of exit holes  84  are offset circumferentially in the direction of arrow  76  as they extend around the circumference of the tile  42 . 
         [0030]    Each exit hole  84  has a leading edge  90  and a trailing edge  92 . The exit holes  84  are offset circumferentially and axially from the adjacent exit hole. For example, the leading edge  90  for the row  86  is offset from the leading edge  90  of the row  88 . This offset stacked arrangement of the leading edges of the exit holes  84  creates an improved effusive cooling arrangement. 
         [0031]      FIG. 5  illustrates an enlarged view taken from circle  5  of  FIG. 4 . Here an enlarged section of one inlet port  70  is shown with cooled air  68  traversing into the air gap  66 . Cooling air  68  then traverses into multiple pathways, for example one upstream  95  and one downstream  97 . The space of the air gap  66  may vary as is desired to provide sufficient cooling volume to the hot side of the tile. As the cooling air  68  passes along path  95  it jets out of the exit holes  84  to the interior of the combustor  18 . However the airflow is quickly aligned with the top surface  82  of the hot skin  64  due to the angle φ of the cooling hole  78  and due to the shape of the exit hole  84 . 
         [0032]      FIG. 6  illustrates an enlarged side sectional view of the cooling hole  78  that is shown in the  FIG. 4  tile assembly  42 . The configuration of the cooling hole  78  has a passageway with inside surfaces that are arcuate shaped  96  that extend from the bottom surface  80  to the top surface  82 . The leading edge  90  has a curved component with a tip  100 . The trailing edge  94  is downstream from the leading edge  90  and the trailing edge  94  has an arcuate shaped surface  102  that blends into the top surface  82  of the hot skin  64 . A centerline is shown with a curved and flowing component  104  that represents a potential flow path of cooling air  68  that may pass through the tile  42 . At a point near the arcuate shaped surface  102  the flow of cooling air  68  is closely offset a distance from the top surface  82  of the hot skin  64 . Such arrangement permits the cooled air  68  to closely traverse near to the top boundary or surface layer  160 . 
         [0033]      FIG. 7  illustrates a top view of the  FIG. 6  exit hole  84  relative to the top surface  82  of the hot skin  64 . The leading edge  90  has a tip  100  and the surface fans towards the trailing edge  94 . This arrangement is a fan type configuration. Other configurations are contemplated, such as the oval shape that is shown in  FIG. 10 . 
         [0034]      FIGS. 8-10  illustrate an alternative configuration  150  of a tile assembly  42 . Here a cold skin  62  and a hot skin  64  are adjoined and include a plurality of inlet cooling ports  70  that feed air to effusion cooling ports  152 . The cooling ports  152  have a centerline  154  that is straight which matches the contour of the internal walls  156  of the port  152 . In the top view shown in  FIG. 10  the exit port  84  is oval shaped. A leading edge  90  and trailing edge  94  represent the extreme axial positions of the exit port  84 . A flow path  156  of air exits the opening and suddenly pushes away along a path  158  that is in turn offset a distance from the top surface  82  of the hot skin  64 . The cooled air must travel a distance x before it reconnects to the film or surface layer  160  of the top surface. The sooner the flow path reconnects to the surface layer  160 , the more effective the cooling performance of the system. 
         [0035]    The tile assembly  42  may be constructed using various manufacturing techniques. For example, one exemplary style of manufacturing could employ DLD (direct laser deposition) processes for creating all features including the angled holes  78  and  152  in the hot skin and also the exit openings  84  on the outside surface of the hot skin. While oval shaped and fan shaped exit openings were illustrated herein, it will be appreciated that other unique shaped configurations may be employed so as to generate flow paths that are beneficial. 
         [0036]    The tile assembly  42  may be constructed primarily of a composite ceramic material (CMC), but other configurations could include a metallic two-piece diffusion or braze bonded assembly of cast, wrought, or direct metal laser sintered (a/k/a direct laser deposition or additive manufactured) components, or a single piece cast or direct metal laser sintered tile. The tile&#39;s hot surface can either be as manufactured or can have a thermal and/or environmental barrier coating applied. The coating could be ceramic. A nut or other anchor can be provided as well so as to provide a mechanical securing mechanism for attaching each assembly  42  to the skin  44 . 
         [0037]    It will be appreciated that the aforementioned method and devices may be modified to have some components and steps removed, or may have additional components and steps added, all of which are deemed to be within the spirit of the present disclosure. Even though the present disclosure has been described in detail with reference to specific embodiments, it will be appreciated that the various modifications and changes can be made to these embodiments without departing from the scope of the present disclosure as set forth in the claims. The specification and the drawings are to be regarded as an illustrative thought instead of merely restrictive thought.