Patent Publication Number: US-9835033-B2

Title: Hybrid airfoil for a gas turbine engine

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of U.S. patent application Ser. No. 13/429,474, filed Mar. 26, 2012. 
    
    
     BACKGROUND 
     This disclosure relates to a gas turbine engine, and more particularly to a hybrid airfoil that can be incorporated into a gas turbine engine. 
     Gas turbine engines typically include a compressor section, a combustor section and a turbine section. During operation, air is pressurized in the compressor section and is mixed with fuel and burned in the combustor section to generate hot combustion gases. The hot combustion gases are communicated through the turbine section, which extracts energy from the hot combustion gases to power the compressor section and other gas turbine engine loads. 
     The compressor section and the turbine section of the gas turbine engine typically include alternating rows of rotating blades and stationary vanes. The rotating blades create or extract energy from the airflow that is communicated through the gas turbine engine, while the vanes direct the airflow to a downstream row of blades. Typically, the blades and vanes are metallic structures that are exposed to relatively high temperatures during gas turbine engine operation. These circumstances may necessitate communicating a cooling airflow through an internal cooling circuit of the blades and vanes. 
     SUMMARY 
     A hybrid airfoil according to an exemplary aspect of the present disclosure includes, among other things, a leading edge portion made of a first material, a trailing edge portion made of a second material, and an intermediate portion between the leading edge portion and the trailing edge portion made of a non-metallic material. A rib is disposed between the leading edge portion and the intermediate portion. A protrusion of one of the rib and the intermediate portion is received within a pocket of the other of the rib and the intermediate portion. 
     In a further non-limiting embodiment of the foregoing hybrid airfoil, the first material is a metallic material and the second material is a non-metallic material. 
     In a further non-limiting embodiment of either of the foregoing hybrid airfoils, the first material and the second material are both metallic materials. 
     In a further non-limiting embodiment of any of the foregoing hybrid airfoils, the non-metallic material is one of a ceramic material and a ceramic matrix composite (CMC) material. 
     In a further non-limiting embodiment of any of the foregoing hybrid airfoils, a portion between the leading edge portion and the intermediate portion includes a pocket that receives another non-metallic portion. 
     In a further non-limiting embodiment of any of the foregoing hybrid airfoils, an intermediate bonding layer is disposed between the leading edge portion and the another non-metallic portion. 
     In a further non-limiting embodiment of any of the foregoing hybrid airfoils, each of the leading edge portion, the trailing edge portion and the intermediate portion extend between an inner platform and an outer platform. 
     In a further non-limiting embodiment of any of the foregoing hybrid airfoils, the rib extends between the inner platform and the outer platform. 
     In a further non-limiting embodiment of any of the foregoing hybrid airfoils, the rib is a metallic structure. 
     In a further non-limiting embodiment of any of the foregoing hybrid airfoils, the intermediate portion includes an oxide material including at least one of silica, alumina, zirconia, yttria and titania. 
     In a further non-limiting embodiment of any of the foregoing hybrid airfoils, the intermediate portion includes a non-oxide material including at least one of a carbide, a boride, a nitride, and a silicide. 
     In a further non-limiting embodiment of any of the foregoing hybrid airfoils, the leading edge portion and the trailing edge portion include radial cooling passages and the intermediate portion excludes radial cooling passages. 
     A hybrid airfoil according to another exemplary aspect of the present disclosure includes, among other things, a metallic portion, a first non-metallic portion connected to the metallic portion and a pocket formed in the metallic portion and configured to receive a second non-metallic portion. 
     In a further non-limiting embodiment of the foregoing hybrid airfoil, the first non-metallic portion is an intermediate portion of the hybrid airfoil. 
     In a further non-limiting embodiment of either of the foregoing hybrid airfoils, the second non-metallic portion is disposed between a leading edge portion and a rib of the hybrid airfoil. 
     The various features and advantages of this disclosure will become apparent to those skilled in the art from the following detailed description. The drawings that accompany the detailed description can be briefly described as follows. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  illustrates a schematic, cross-sectional view of a gas turbine engine. 
         FIG. 2  illustrates a hybrid airfoil that can be incorporated into a gas turbine engine. 
         FIG. 3  illustrates a cross-sectional view of the hybrid airfoil of  FIG. 2 . 
         FIG. 4  illustrates another hybrid airfoil that can be incorporated into a gas turbine engine. 
         FIG. 5  illustrates a portion of yet another hybrid airfoil. 
         FIG. 6  illustrates a blow up of a portion of the hybrid airfoil of  FIG. 4 . 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  schematically illustrates a gas turbine engine  20 . The exemplary gas turbine engine  20  is a two-spool turbofan engine that generally incorporates a fan section  22 , a compressor section  24 , a combustor section  26  and a turbine section  28 . Alternative engines might include an augmenter section (not shown) among other systems or features. The fan section  22  drives air along a bypass flow path B, while the compressor section  24  drives air along a core flow path C for compression and communication into the combustor section  26 . The hot combustion gases generated in the combustor section  26  are expanded through the turbine section  28 . Although depicted as a turbofan gas turbine engine in the disclosed non-limiting embodiment, it should be understood that the concepts described herein are not limited to turbofan engines and these teachings could extend to other types of turbine engines, including but not limited to three-spool engine architectures. 
     The gas turbine engine  20  generally includes a low speed spool  30  and a high speed spool  32  mounted for rotation about an engine centerline longitudinal axis A relative to an engine static structure  33  via several bearing structures  31 . It should be understood that various bearing structures  31  at various locations may alternatively or additionally be provided. 
     The low speed spool  30  generally includes an inner shaft  34  that interconnects a fan  36 , a low pressure compressor  38  and a low pressure turbine  39 . The high speed spool  32  includes an outer shaft  35  that interconnects a high pressure compressor  37  and a high pressure turbine  62 . In this example, the inner shaft  34  and the outer shaft  35  are supported at various axial locations by bearing structures  31  positioned within the engine static structure  33 . 
     A combustor  55  is arranged between the high pressure compressor  37  and the high pressure turbine  62 . A mid-turbine frame  57  of the engine static structure  33  is arranged generally between the high pressure turbine  62  and the low pressure turbine  39 . The mid-turbine frame  57  can support one or more bearing structures  31  in the turbine section  28 . The inner shaft  34  and the outer shaft  35  are concentric and rotate via the bearing structures  31  about the engine centerline longitudinal axis A, which is collinear with their longitudinal axes. 
     The core airflow is compressed by the low pressure compressor  38  and the high pressure compressor  37 , is mixed with fuel and burned in the combustor  55 , and is then expanded over the high pressure turbine  62  and the low pressure turbine  39 . The mid-turbine frame  57  includes airfoils  59  which are in the core airflow path. The high pressure turbine  62  and the low pressure turbine  39  rotationally drive the respective low speed spool  30  and the high speed spool  32  in response to the expansion. 
     The compressor section  24  and the turbine section  28  can each include alternating rows of rotor assemblies  21  and vane assemblies  23 . The rotor assemblies  21  include a plurality of rotating blades, and each vane assembly  23  includes a plurality of vanes. The blades of the rotor assemblies  21  create or extract energy (in the form of pressure) from the airflow that is communicated through the gas turbine engine  20 . The vanes of the vane assemblies  23  direct airflow to the blades of the rotor assemblies  21  to either add or extract energy. 
       FIG. 2  illustrates a hybrid airfoil  40  that can be incorporated into a gas turbine engine, such as the gas turbine engine  20  of  FIG. 1 . In this example, the hybrid airfoil  40  is a vane of a vane assembly of either the compressor section  24  or the turbine section  28 . However, the teachings of this disclosure are not limited to vane-type airfoils and could extend to other airfoils, including but not limited to, the airfoils of a gas turbine engine mid-turbine frame. This disclosure could also extend to non-airfoil hardware including stationary structures of the gas turbine engine  20 . 
     The hybrid airfoil  40  of this exemplary embodiment includes at least one metallic portion  100  and at least one non-metallic portion  102 . Therefore, as used in this disclosure, the term “hybrid” is intended to denote a structure that includes portions made from at least two different materials, such as a metallic portion and a non-metallic portion. 
     In the exemplary embodiment, the hybrid airfoil  40  includes a hybrid airfoil body  42  that extends between an inner platform  44  (on an inner diameter side) and an outer platform  46  (on an outer diameter side). The hybrid airfoil body  42  includes a leading edge portion  48 , a trailing edge portion  50 , an intermediate portion  51  disposed between the leading edge portion  48  and the trailing edge portion  50 , a pressure side  52  and a suction side  54 . In one non-limiting embodiment, the leading edge portion  48  and the trailing edge portion  50  may establish the metallic portions  100  of the hybrid airfoil body  42 , while the intermediate portion  51  may establish a non-metallic portion  102  of the hybrid airfoil body  42 . 
     The hybrid airfoil body  42  can also include a rib  56  disposed between the leading edge portion  48  and the intermediate portion  51 . The rib  56  extends between the inner platform  44  and the outer platform  46  and can extend across an entire distance between the pressure side  52  and the suction side  54  of the hybrid airfoil body  42  (See  FIG. 3 ). In the exemplary embodiment, the rib  56  is a metallic structure that can add structural rigidity to the hybrid airfoil  40  and serve as an additional tie between the inner platform  44  and the outer platform  46 . 
       FIG. 3  illustrates a cross-sectional view of a hybrid airfoil body  42  of the hybrid airfoil  40 . The hybrid airfoil body  42  includes the leading edge portion  48 , the trailing edge portion  50 , and the intermediate portion  51  disposed between the leading edge portion  48  and the trailing edge portion  50 . The leading edge portion  48  can be made of a first material, the trailing edge portion  50  can be made of a second material and the intermediate portion  51  can be made of a third material. The first material, the second material and the third material are at least two different materials, in one example. 
     In this exemplary embodiment, the first material and the second material are metallic materials and the third material is a non-metallic material. Example metallic materials that can be used to manufacture the leading edge portion  48  and the trailing edge portion  50  include, but are not limited to, nickel based super alloys and cobalt based super alloys. The second material could also include a non-metallic material such as a monolithic ceramic. The third material can include a non-metallic material such as a ceramic material. In another example, the intermediate portion  51  is made of a ceramic matrix composite (CMC). Non-limiting examples of materials that can be used to provide the intermediate portion  51  include oxides such as silica, alumina, zirconia, yttria, and titania, non-oxides such as carbides, borides, nitrides, and silicides, any combination of oxides and non-oxides, composites including particulate or whisker reinforced matrices, and cermets. These materials are not intended to be limiting on this disclosure as other materials may be suitable for use as the non-metallic portion of the hybrid airfoil  40 . 
     Each of the leading edge portion  48  and the trailing edge portion  50  can include one or more cooling passages  58  that radially extend through the hybrid airfoil body  42  (i.e., between the inner platform  44  and the outer platform  46 ). The cooling passages  58  establish an internal circuit for the communication of cooling airflow, such as a bleed airflow, that can be communicated through the hybrid airfoil body  42  to cool the hybrid airfoil  40 . In the illustrated embodiment, the intermediate portion  51  does not include a cooling passage because the non-metallic nature of the intermediate portion  51  may not require dedicated cooling. However, if desired, and depending upon certain design and operability characteristics, one or more cooling passages could be disposed through the intermediate portion  51  to provide additional cooling. 
       FIG. 4  illustrates another example hybrid airfoil  140 . In this disclosure, like reference numerals signify like features, and reference numerals identified in multiples of 100 signify slightly modified features. Moreover, select features from one example embodiment may be combined with select features from other example embodiments within the scope of this disclosure. 
     The hybrid airfoil  140  includes at least one metallic portion  100  (i.e., a cobalt or nickel based super alloy) and one or more non-metallic portions  102  (i.e., a ceramic or CMC). This exemplary embodiment illustrates two non-metallic portions  102 A,  102 B, although it should be understood that the hybrid airfoil  140  could include any number of non-metallic portions  102  to reduce weight and dedicated cooling requirements of the hybrid airfoil  140 . For example, the hybrid airfoil  140  could include two different non-metallic regions with the intermediate portion  151  being a CMC or a ceramic material and the trailing edge portion  150  being made of a monolithic ceramic. In this exemplary embodiment, the metallic portion  100  is a leading edge portion  148  of the hybrid airfoil  140 , the non-metallic portion  102 A is a portion  115  of the hybrid airfoil  140  between the leading edge portion  148  and a rib  156 , and the non-metallic portion  102 B is an intermediate portion  151  of the hybrid airfoil  140 . The portion  115  can be disposed either on the pressure side  152  of the hybrid airfoil  140  (as shown in  FIG. 4 ), the suction side  154  of the hybrid airfoil  140 , or both. In this example, the portion  115  is positioned on the pressure side  152 , although this disclosure is not limited to this particular embodiment. 
     The rib  156  of this exemplary embodiment is metallic and includes a pocket  106  that faces toward the intermediate portion  151  (i.e., the pocket  106  faces in a direction away from the leading edge portion  148 ). A protruding portion  108  of the intermediate portion  151  is received within the pocket  106  to connect the non-metallic portion  102 B to the metallic portion  100  of the hybrid airfoil  140 . An opposite configuration is also contemplated in which a protruding portion  110  of the metallic portion  100  is received within a pocket  112  of the non-metallic portion  102  to attach these components (See  FIG. 5 ). In addition, other connections between metallic and non-metallic portions can be provided on the hybrid airfoil  140 , such as between the intermediate portion  151  and a trailing edge portion  150 . 
       FIG. 6  illustrates additional features of the portion  115  of the hybrid airfoil  140 , which establishes a connection interface  114  between a metallic portion  100  and a non-metallic portion  102 A of a hybrid airfoil  140 . In this example, the connection interface  114  is located at location A of  FIG. 4 . At location A, an outer surface  118  of the non-metallic portion  102 A faces a gas path that is communicated across the hybrid airfoil  140 . In this exemplary embodiment, a protrusion  125  of the non-metallic portion  102 A is received in a pocket  127  of the metallic portion  100 . 
     An intermediate bonding layer  116  can be disposed between the metallic portion  100  and the non-metallic portion  102 A of the hybrid airfoil  140 . The intermediate bonding layer  116  provides a transitional interface between the metallic portion  100  and the non-metallic portion  102  and provides a buffer between the 100% metal alloy of the metallic portion  100  and the 100% non-metallic portion  102  to accommodate any mismatch in mechanical properties and thermal expansion of the metallic portion  100  as compared to the non-metallic portion  102 . Although not depicted as such in  FIG. 4 , an intermediate bonding layer could also be disposed between the metallic rib  156  and the non-metallic portion  102 B. The intermediate bonding layer  116  could also be mechanically trapped between the metallic portion  100  and the non-metallic portion  102 A (i.e., the intermediate bonding layer  116  is not necessarily bonded to the various surfaces). 
     In one non-limiting embodiment, a gradient of the intermediate bonding layer  116  is a multi-graded layer. In other words, the gradient of the intermediate bonding layer  116  transitions across its thickness from 100% metal alloy to 100% non-metal material (from right to left in  FIG. 6 ). It should be appreciated that the transition may be linear or non-linear as required. The required gradient may be determined based on design experimentation or testing to achieve the desired transition. 
     The intermediate bonding layer  116  may, for example, be a nanostructured functionally graded material (FGM). The FGM includes a variation and composition in structure gradually over volume, resulting in corresponding changes in the properties of the material for specific function and applications. Various approaches based on the bulk (particulate processing), preformed processing, layer processing and melt processing can be used to fabricate the FGM, including but not limited to, electron beam powder metallurgy technology, vapor deposition techniques, electromechanical deposition, electro discharge compaction, plasma-activated sintering, shock consolidation, hot isostatic pressing, Sulzer high vacuum plasma spray, etc. 
     Although the different examples have specific components shown in the illustrations, embodiments of this disclosure are not limited to those particular combinations. It is possible to use some of the components or features from one of the examples in combination with features or components from another one of the examples. 
     Furthermore, the foregoing description shall be interpretative as illustrated and not in any limiting sense. A worker of ordinary skill in the art would understand that certain modifications could come within the scope of this disclosure. For these reasons, the following claims should be studied to determine the true scope and content of this disclosure.