Ceramic matrix composite airfoil for a gas turbine engine

The present disclosure relates to a gas turbine engine, and more particularly to Ceramic Matrix Composites (CMC) components therefor.

The turbine section of a gas turbine engine includes a multiple of airfoils which operate at elevated temperatures in a strenuous, oxidizing type of gas flow environment and are typically manufactured of high temperature superalloys. CMC materials provide higher temperature capability than metal alloys and a high strength to weight ratio. CMC materials, however, may require particular manufacturing approaches as the fiber orientation primarily determines the strength capability.

A Ceramic Matrix Composites (CMC) airfoil for a gas turbine engine according to an exemplary aspect of the present disclosure includes a first multiple of CMC plies which define a suction side, a first airfoil portion of the first multiple of CMC plies at least partially parallel to an airfoil axis. A second multiple of CMC plies define a pressure side, a second airfoil portion of the second multiple of CMC plies at least partially parallel to the airfoil axis and bonded to the first airfoil portion.

A Ceramic Matrix Composites (CMC) airfoil for a gas turbine engine according to an exemplary aspect of the present disclosure includes a first multiple of CMC plies which define a suction side, a first airfoil portion of the first multiple of CMC plies at least partially parallel to an airfoil axis and a first fillet portion of the first multiple of CMC plies transverse to the airfoil axis. A second multiple of CMC plies define a pressure side, a second airfoil portion of second multiple of CMC plies at least partially parallel to the airfoil axis and a second fillet portion of the second multiple of CMC plies transverse to the airfoil axis. A third multiple of CMC plies bonded to the first fillet portion of the first multiple of CMC plies and the second fillet portion of the second multiple of CMC plies, the third multiple of CMC plies transverse to the airfoil axis to define a generally triangular area. A CMC fabric filler material within the generally triangular area.

A method of forming a Ceramic Matrix Composite airfoil for a gas turbine engine according to an exemplary aspect of the present disclosure includes forming a suction side from a first multiple of CMC plies, a first airfoil portion of the first multiple of CMC plies at least partially parallel to an airfoil axis; forming a pressure side from a second multiple of CMC plies, a second airfoil portion of the second multiple of CMC plies at least partially parallel to the airfoil axis; and bonding the first airfoil portion of the first multiple of CMC plies to the second airfoil portion of the second multiple of CMC plies.

Various features will become apparent to those skilled in the art from the following detailed description of the disclosed non-limiting embodiment. The drawings that accompany the detailed description can be briefly described as follows:

FIG. 1 is a schematic cross-section of a gas turbine engine;

FIG. 2 is an enlarged sectional view of a Low Pressure Turbine section of the gas turbine engine;

FIG. 3 is an enlarged perspective view of an example rotor disk of the Low Pressure Turbine section;

FIG. 4 is an enlarged perspective view of an example stator vane structure of the Low Pressure Turbine section;

FIG. 5 is a perspective view of a CMC vane structure for a gas turbine engine;

FIG. 6 is an exploded view of the CMC vane structure illustrating a ply arrangement disclosed herein;

FIG. 7 is a perspective schematic view of the CMC airfoil structure illustrating a chevron platform; and

FIG. 8 is an enlarged front perspective view of a CMC airfoil bonded within an inner and outer full hoop ring.

FIG. 1 schematically illustrates a gas turbine engine 20 . The gas turbine engine 20 is disclosed herein as a two-spool turbofan 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 augmentor section (not shown) among other systems or features. The fan section 22 drives air along a bypass flowpath while the compressor section 24 drives air along a core flowpath for compression and communication into the combustor section 26 then expansion 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 use with turbofans as the teachings may be applied to other types of turbine engines.

The engine 20 generally includes a low speed spool 30 and a high speed spool 32 mounted for rotation about an engine central longitudinal axis A relative to an engine static structure 36 via several bearing systems 38 . It should be understood that various bearing systems 38 at various locations may alternatively or additionally be provided.

The low speed spool 30 generally includes an inner shaft 40 that interconnects a fan 42 , a low pressure compressor 44 and a low pressure turbine 46 . The inner shaft 40 is connected to the fan 42 through a geared architecture 48 to drive the fan 42 at a lower speed than the low speed spool 30 . The high speed spool 32 includes an outer shaft 50 that interconnects a high pressure compressor 52 and high pressure turbine 54 . A combustor 56 is arranged between the high pressure compressor 52 and the high pressure turbine 54 . The inner shaft 40 and the outer shaft 50 are concentric and rotate about the engine central longitudinal axis A which is collinear with their longitudinal axes.

The core airflow is compressed by the low pressure compressor 44 then the high pressure compressor 52 , mixed and burned with fuel in the combustor 56 , then expanded over the high pressure turbine 54 and low pressure turbine 46 . The turbines 54 , 46 rotationally drive the respective low speed spool 30 and high speed spool 32 in response to the expansion.

With reference to FIG. 2 , the low pressure turbine 46 generally includes a low pressure turbine case 60 with a multiple of low pressure turbine stages. The stages include a multiple of rotor structures 62 A, 62 B, 62 C interspersed with vane structures 64 A, 64 B. Each of the rotor structures 62 A, 62 B, 62 C and each of the vane structure 64 A, 64 B may include airfoils 66 manufactured of a ceramic matrix composite (CMC) material typically in a ring-strut ring full hoop structure ( FIGS. 3 and 4 ). It should be understood that examples of CMC material for all componentry discussed herein may include, but are not limited to, for example, S200 and SiC/SiC. It should also be understood that the term full hoop is defined herein as an uninterrupted member such that the vanes do not pass through apertures formed therethrough. Although depicted as a low pressure turbine in the disclosed embodiment, it should be understood that the concepts described herein are not limited to use with low pressure turbine as the teachings may be applied to other sections such as high pressure turbine, high pressure compressor, low pressure compressor and intermediate pressure turbine and intermediate pressure turbine of a three-spool architecture gas turbine engine.

With reference to FIG. 5 , one CMC airfoil 66 usable with a ring-strut-ring full hoop structure is illustrated. Although a somewhat generic airfoil 66 will be described in detail hereafter, it should be understood that various rotary airfoils or blades and static airfoils or vanes such as those within the low pressure turbine 46 and high pressure compressor 52 may be particularly amenable to the fabrication described herein.

The CMC airfoil 66 generally includes an airfoil portion 68 defined between a leading edge 70 and a trailing edge 72 . Each airfoil 66 may include a fillet section 74 , 76 to provide a transition between the airfoil portion 68 and a platform segment 78 , 80 . The platform segments 78 , 80 form the inner diameter and the outer diameter of the core gas path. The airfoil portion 68 includes a generally concave shaped portion which forms a pressure side 82 and a generally convex shaped portion which forms a suction side 84 .

With reference to FIG. 6 , the fabrication of each CMC airfoil 66 may be performed in several steps to form the various features. The pressure side 82 and the suction side 84 are formed from a respective first and second multiple of CMC plies 86 , 88 which may be bonded together along the central portion of an airfoil axis B within a first airfoil portion 86 A, 88 A which is at least partially parallel to the airfoil axis B of the airfoil portion 68 . The airfoil portion 68 may be fabricated such that the CMC structural fibers of the respective first and second multiple of CMC plies 86 , 88 are arranged to define a radius outward from the airfoil axis B. That is, the pressure side 82 and the suction side 84 along with the inner and outer core gas path forming platform segments 78 , 80 are formed with a generally “C” shaped CMC ply orientation by the respective first and second multiple of CMC plies 86 , 88 .

The multiple of CMC plies 86 , 88 bend apart to define a generally perpendicular orientation to form the fillets 74 , 76 . That is, the multiple of CMC plies 86 , 88 bend apart at a second airfoil portion 86 B, 88 B which is at least partially transverse to the airfoil axis B to form the fillet sections 74 , 76 . The fillet sections 74 , 76 define the core gas path surface which blend the airfoil portion 68 into the platform segments 78 , 80 . The outer cap surfaces 90 , 92 of the platform segments 78 , 80 are then capped by, for example, a third and fourth multiple of CMC plies 94 , 96 which are generally transverse to the airfoil axis B. The platform segments 78 , 80 may additionally or alternatively include fabric plies to obtain a thicker section if so required.

The outer cap surfaces 90 , 92 of the platform segments 78 , 80 utilize the CMC hoop strength characteristics to form an integrated bladed rotor with a full hoop shroud to form a ring-strut-ring structure. It should be understood that the term full hoop is defined herein as an uninterrupted member such that the vanes do not pass through apertures formed therethrough.

Triangular areas 98 , 100 at which the multiple of CMC uni-tape plies 86 , 88 bend apart to form the fillets 74 , 76 are filled with a CMC fabric filler materials 102 such as chopped fiber and a tackifier. The CMC fabric filler material may additionally be utilized in areas where pockets or lack of material will exist relative to the forming of a feature. These areas may possess debited properties but will be located in areas where they may exist without compromising structural integrity.

In the disclosed non-limiting embodiment, the platform segments 78 , 80 may be chevron-shaped ( FIG. 7 ) to provide a complementary geometry for abutting edge engagement of each adjacent platform segment to define the inner and outer core gas path. That is, the CMC airfoils 66 are assembled in an adjacent complementary manner to form a ring of airfoils which are further wrapped with a CMC outer ring 104 and a CMC inner ring 102 about the multiple of the respectively adjacent platform segments 78 , 80 to form full hoops ( FIG. 8 ). It should be understood that appropriate twist and the like may be readily included.

The disclosed fabrication approach allows for ease of production for a single or multiple airfoil cluster based on relatively simple shapes joined together to form the relatively more complex airfoil structure.

It should be understood that like reference numerals identify corresponding or similar elements throughout the several drawings. It should also be understood that although a particular component arrangement is disclosed in the illustrated embodiment, other arrangements will benefit herefrom.

Although particular step sequences are shown, described, and claimed, it should be understood that steps may be performed in any order, separated or combined unless otherwise indicated and will still benefit from the present disclosure.

The foregoing description is exemplary rather than defined by the limitations within. Various non-limiting embodiments are disclosed herein, however, one of ordinary skill in the art would recognize that various modifications and variations in light of the above teachings will fall within the scope of the appended claims. It is therefore to be understood that within the scope of the appended claims, the disclosure may be practiced other than as specifically described. For that reason the appended claims should be studied to determine true scope and content.