Patent Publication Number: US-11041392-B2

Title: Attachment faces for clamped turbine stator of a gas turbine engine

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a Continuation of U.S. patent application Ser. No. 14/841,943, filed Sep. 1, 2015, which claims the benefit of U.S. patent application Ser. No. 62/047,710, filed Sep. 9, 2014. 
    
    
     BACKGROUND 
     The present disclosure relates to airfoil components for a gas turbine engine, and more particularly, to attachment faces for a turbine stator which itself has an airfoil with endwall platforms and which is radially compressed between supporting structural details. 
     Gas turbine engines, such as those that power modern commercial and military aircraft, generally include a compressor to pressurize an airflow, a combustor to burn a hydrocarbon fuel in the presence of the pressurized air, and a turbine to extract energy from the resultant combustion gases. The compressor and turbine sections include rotatable blade and stationary vane arrays. The blades and vanes typically include low and high-pressure airfoils, vanes, vane rings, shrouds, and nozzle segments. 
     The stationary vane arrays are typically assembled between outer and inner shrouds, or rings, in a variety of manners. Although the actual elements may vary in their configuration and construction, one similarity is that the vanes are typically constructed to allow for thermal expansion. The thermal expansion is typically accommodated through assembly of the vanes relatively loosely in the inner and outer shrouds. Although effective, such assembly may result in various stresses. 
     SUMMARY 
     An airfoil fairing shell for a gas turbine engine according to one disclosed non-limiting embodiment of the present disclosure includes an airfoil section between an outer vane endwall and an inner vane endwall, at least one of the outer vane endwall and the inner vane endwall including a radial attachment face, a suction side tangential attachment face, a pressure side tangential attachment face, and an axial attachment face. 
     A further embodiment of the present disclosure includes, wherein the radial attachment face, the suction side tangential attachment face, the pressure side tangential attachment face, and the axial attachment face are formed by a thickened region of at least one of the outer vane endwall and the inner vane endwall. 
     A further embodiment of any of the foregoing embodiments of the present disclosure includes, wherein the radial attachment face, the suction side tangential attachment face, the pressure side tangential attachment face, and the axial attachment face are formed by a thickened region of the inner vane endwall. 
     A further embodiment of any of the foregoing embodiments of the present disclosure includes, wherein the suction side tangential attachment face is parallel to the tangential attachment face. 
     A further embodiment of any of the foregoing embodiments of the present disclosure includes, wherein the suction side tangential attachment face and the pressure side tangential attachment face are non-parallel to the inner vane endwall. 
     A further embodiment of any of the foregoing embodiments of the present disclosure includes, wherein the suction side tangential attachment face and the pressure side tangential attachment face are non-parallel. 
     A further embodiment of any of the foregoing embodiments of the present disclosure includes, wherein the suction side tangential attachment face is generally perpendicular to a resultant aerodynamic load generated by the airfoil. 
     A further embodiment of any of the foregoing embodiments of the present disclosure includes, wherein the suction side tangential attachment face is downstream of an aerodynamic center of a resultant aerodynamic load generated by the airfoil. 
     A further embodiment of any of the foregoing embodiments of the present disclosure includes, wherein the suction side tangential attachment face is aligned with respect to a resultant aerodynamic load generated by the airfoil. 
     A vane ring for a gas turbine engine according to another disclosed non-limiting embodiment of the present disclosure includes a multiple of airfoil fairing shells each with a first attachment face formed by a thickened region of a vane endwall that forms a mateface, each of the multiple of airfoil fairing shells adjacent to another one of the multiple of airfoil fairing shells at the mateface; and a structural support with a multiple of lugs, each of the multiple of lugs interfaces with at least one of the first attachment faces of each of the multiple of airfoil fairing shells. 
     A further embodiment of any of the foregoing embodiments of the present disclosure includes, wherein the structural support includes an interface for attachment to an engine case structure. 
     A further embodiment of any of the foregoing embodiments of the present disclosure includes, wherein the structural support is an arcuate segment. 
     A further embodiment of any of the foregoing embodiments of the present disclosure includes, wherein the structural support is a full ring. 
     A further embodiment of any of the foregoing embodiments of the present disclosure includes, wherein the lug extends transverse to the mateface of the vane endwall. 
     A further embodiment of any of the foregoing embodiments of the present disclosure includes, wherein the thickened region of the vane endwall forms a radial attachment face, an axial attachment face, and a pressure side tangential attachment face. 
     A further embodiment of any of the foregoing embodiments of the present disclosure includes, wherein the first attachment face is a suction side tangential attachment face. 
     A further embodiment of any of the foregoing embodiments of the present disclosure includes, wherein the axial attachment face, the pressure side tangential attachment face, and the suction side tangential attachment face are generally perpendicular to the radial attachment face. 
     A further embodiment of any of the foregoing embodiments of the present disclosure includes, wherein the axial attachment face, is generally perpendicular to the pressure side tangential attachment face and the suction side tangential attachment face. 
     A further embodiment of any of the foregoing embodiments of the present disclosure includes, wherein the suction side tangential attachment face is downstream of an aerodynamic center of a resultant aerodynamic load generated by the airfoil fairing shell such that the in plane loading to the reaction forces on these faces is compressive. 
     A further embodiment of any of the foregoing embodiments of the present disclosure includes, wherein the suction side tangential attachment face and the axial attachment face are downstream of an aerodynamic center of a resultant aerodynamic load generated by the airfoil fairing shell such that the in plane loading to the reaction forces on these faces is compressive. 
     The foregoing features and elements may be combined in various combinations without exclusivity, unless expressly indicated otherwise. These features and elements as well as the operation thereof will become more apparent in light of the following description and the accompanying drawings. It should be understood, however, the following description and drawings are intended to be exemplary in nature and non-limiting. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       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 an example gas turbine engine architecture; 
         FIG. 2  is a schematic cross-section of another example gas turbine engine architecture; 
         FIG. 3  is an enlarged schematic cross-section of an engine turbine section; 
         FIG. 4  is an enlarged schematic cross-section of an engine turbine section airfoil fairing shell according to one disclosed non-limiting embodiment; 
         FIG. 5  is a perspective view of turbine vane ring; 
         FIG. 6  is an enlarged perspective partial phantom view of the turbine vane ring; 
         FIG. 7  is a top partial phantom view of an airfoil fairing shell according to another disclosed non-limiting embodiment; 
         FIG. 8  is a top partial phantom view of an airfoil fairing shell according to another disclosed non-limiting embodiment; 
         FIG. 9  is a top partial phantom view of an airfoil fairing shell according to another disclosed non-limiting embodiment; 
         FIG. 10  is a top partial phantom view of an airfoil fairing shell according to another disclosed non-limiting embodiment; and 
         FIG. 11  is a top partial phantom view of an airfoil fairing shell according to another disclosed non-limiting embodiment. 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  schematically illustrates a gas turbine engine  20 . The gas turbine engine  20  is disclosed herein as a two-spool turbo fan that generally incorporates a fan section  22 , a compressor section  24 , a combustor section  26 , and a turbine section  28 . Alternative engine architectures  200  might include an augmentor section  12 , an exhaust duct section  14 , and a nozzle section  16  ( FIG. 2 ) among other systems or features. The fan section  22  drives air along a bypass flowpath and into the compressor section  24  to drive core air along a core flowpath. The core air is compressed then communicated into the combustor section  26  for downstream expansion through the turbine section  28 . Although depicted as a turbofan in the disclosed non-limiting embodiment, it should be appreciated that the concepts described herein are not limited, only to turbofans as the teachings may be applied to other types of turbine engine architectures such as turbojets, turboshafts, and three-spool (plus fan) turbofans. 
     The engine  20  generally includes a low spool  30  and a high spool  32  mounted for rotation about an engine central longitudinal axis A relative to an engine case structure  36  via several bearing compartments  38 . The low spool  30  generally includes an inner shaft  40  that interconnects a fan  42 , a low pressure compressor (“LPC”)  44  and a low pressure turbine (“LPT”)  46 . The inner shaft  40  drives the fan  42  directly or through a geared architecture  48  to drive the fan  42  at a lower speed than the low spool  30 . An exemplary reduction transmission is an epicyclic transmission, namely a planetary or star gear system. 
     The high spool  32  includes an outer shaft  50  that interconnects a high pressure compressor (“HPC”)  52  a and high pressure turbine (“HPT”)  54 . A combustor  56  is arranged between the HPC  52  and the HPT  54 . Core airflow is compressed by the LPC  44 , then the HPC  52 , mixed with the fuel and burned in the combustor  56 , then expanded over the HPT  54  and the LPT  46  which rotationally drive the respective low spool  30  and high spool  32  in response to the expansion. 
     With reference to  FIG. 3 , an enlarged schematic view of a portion of the HPT  54  is shown by way of example; however, other engine sections will also benefit herefrom. A shroud assembly  60  mounted to the engine case structure  36  supports a Blade Outer Air Seal (BOAS) assembly  62  with a multiple of circumferentially distributed BOAS  64  proximate to a rotor assembly  66  (one schematically shown). 
     The shroud assembly  60  and the BOAS assembly  62  are axially disposed between a forward stationary vane ring  68  and an aft stationary vane ring  70 . The rotor assembly  66  includes an array of blades  84  circumferentially disposed around a disk  86 . Each blade  84  includes a root  88 , a platform  90 , and an airfoil  92 . The blade roots  88  are received within a rim  94  of the disk  86  and the airfoils  92  extend radially outward such that a tip  96  of each airfoil  92  adjacent to the blade outer air seal (BOAS) assembly  62 . The platform  90  separates a gas path side inclusive of the airfoil  92  and a non-gas path side inclusive of the root  88 . 
     With reference to  FIG. 4 , the forward stationary vane ring  68  will be described as a clamped stator assembly, however, it should be appreciated that the aft stationary vane ring  70  as well as other vane rings in the turbine section and the compressor section will also benefit herefrom. In the example forward stationary vane ring  68 , each airfoil  72  extends between a respective inner vane endwall  76  and an outer vane endwall  80  to form an airfoil fairing shell  106 . Each airfoil fairing shell  106  is respectively clamped between an outer structural support  110 , and an inner structural support  112  (also shown in  FIG. 5 ). 
     The outer structural support  110 , and the inner structural support  112  may be full rings or circumferentially segmented structures that are mounted within or a portion of the engine case structure  36 , or attached thereto via fasteners, clamping, pins, or other such interface  114 ,  116  (illustrated schematically). That is, the airfoil fairing shells  106  are clamped into a full ring or circumferentially segmented outer and inner structural support  110 ,  112  that are, in turn, formed, fastened or otherwise located in the engine case structure  36  ( FIG. 3 ). In the example circumferentially segmented structure, each segment of the outer structural support  110  and/or the inner structural support  112  may support a cluster of one or more airfoil fairing shells  106  (three shown in  FIG. 6 ). 
     With reference to  FIG. 7 , each airfoil  72  defines a blade chord between a leading edge  120 , which may include various forward and/or aft sweep configurations, and a trailing edge  122 . A first airfoil sidewall  124  that may be convex to define a suction side, and a second airfoil sidewall  126  that may be concave to define a pressure side, are joined at the leading edge  120  and at the axially spaced trailing edge  122 . An aerodynamic center “C” of the airfoil is located at about a quarter chord position, however, such aerodynamic centers may vary dependent upon the airfoil. 
     The inner vane endwall  76  and the outer vane endwall  80  are generally a parallelogram, chevron, arc, or other shape when viewed from the top and generally includes a respective forward edge  130 ,  132 , an aft edge  134 ,  136  and a mateface  138 A,  138 B,  140 A,  140 B therebetween. The endwalls  70 ,  80  may be cylindrical, conical, arbitrary axisymmetric, or non-axisymmetric when viewed in cross-section. The non-gaspath face of the platform may be any of these as well. That is, the airfoil  72 , the inner vane endwall  76 , and the outer vane endwall  80  form the airfoil fairing shell  106  that is radially clamped by the outer structural support  110 , and the inner structural support  112 . 
     The airfoil fairing shell  106  may include passages “P” (three shown) for cooling airflow and or electrical conduits, may be solid, may be hollow, or combinations thereof. Such an arrangement facilitates manufacture of metallic or non-metallic airfoil fairing shells, particularly but not exclusively those of low-ductility and/or low coefficient of thermal expansion materials, that are readily assembled to the outer structural support and the inner structural support which, in turn, are manufactured of metallic or non-metallic material and which may be manufactured from the same material as or dissimilar material to the airfoil fairing shells. 
     In this disclosed non-limiting embodiment, the outer vane endwall  80  will be described, however, it should be appreciated that the inner vane endwall  76  as well as other vane rings will also benefit herefrom. The outer vane endwall  80  generally includes a radial attachment face  150  spaced from an inner face  81 , a suction side tangential attachment face  152 , a pressure side tangential attachment face  154 , and an axial attachment face  156 . The suction side tangential attachment face  152 , the pressure side tangential attachment face  154 , and the axial attachment face  156  extends from the inner face  81  to the radial attachment face  150  to form a stepped surface. The attachment faces  150 ,  152 ,  154 ,  156  transmit axial and tangential aerodynamic loads from the airfoil fairing shell  106  into the structural supports and transmit clamping load through the fairing shell. 
     The airfoil fairing shell  106  include cylindrical, conical, arbitrary axisymmetric or planar radial attachment faces through which the spanwise clamping load is generally transmitted, and two pairs of orthogonal planar attachment faces through which aerodynamic loads and retention loads are generally transmitted, and which are quasi-orthogonal to the radial direction at the airfoil&#39;s circumferential station. It should be appreciated that one attachment face may be the primary attachment face while another attachment face is a secondary attachment face with respect configurations where the faces are rotated with respect to the engine axis. Axial and tangential oriented primary and secondary attachment faces are one disclosed non-limiting embodiment. More generally, primary and secondary attachment faces, where axial and tangentially aligned are one specific type, where primary aligned with the resultant load is another specific type, and where primary aligned with the platform mateface edge is a third type. The primary and secondary are orthogonal to one another, and are quasi-orthogonal to the radial direction at the airfoil&#39;s circumferential station. 
     The attachment faces  150 ,  152 ,  154 ,  156  are generally formed by thickened areas of the outer vane endwall  80  or other features such as tabs that are arranged to form these faces and interface with respective attachment faces formed by the associated outer structural support  110  ( FIG. 6 ). In this disclosed non-limiting embodiment, the outer structural support  110  includes a series of lugs  160  provide tangential reaction faces that may be angled with respect to the engine axis A and extend transverse to a respective circumferential interface  170  between each airfoil fairing shell  106  ( FIG. 6, 9, 10 ). Alternatively, the series of lugs  160  provide tangential reaction faces is parallel to the engine axis ( FIG. 7 ). 
     The attachment faces  150 ,  152 ,  154 ,  156  are arranged to transmit loads between the respective structural supports  110 ,  112  and the airfoil fairing shell  106 . The surface of the thickened area of the airfoil fairing shell  106  forms the radial attachment face  150  that is clamped between the outer and inner structural support  110 ,  112 . 
     The attachment faces  152 ,  154 ,  156  react in-plane loads formed by the step transitions of the thickened areas of the outer vane endwall  80 . The attachment faces  152 ,  154 ,  156  may be aligned with the axial and tangential directions or rotated to an arbitrary angle, such as that which presents a large face perpendicular to the resultant aerodynamic load ( FIG. 9 ). The suction side tangential attachment face  152  is tasked with reacting aerodynamic in-plane loads and may be located downstream, and to the suction side of the aerodynamic center “C” of the airfoil such that aerodynamic loads tend to create compressive rather than tensile loads in the material that are in the plane with the platform between the aerodynamic center “C” to the attachment faces. That is, the suction side tangential attachment face  152  interfaces with one of the series of lugs  160  of the structural support  110  to provide a primary reaction load. The axial attachment face  156  also interfaces with the structural support  110  to provide a secondary reaction load. 
     In this disclosed non-limiting embodiment, the primary reaction load and the secondary reaction load are non-parallel to the resultant aerodynamic load from the aerodynamic center “C” as generated by the airfoil  72 , and the suction side tangential attachment face  152  is non-parallel to the matefaces  138 A,  138 B. Here, the suction side tangential attachment face  152  and the pressure side tangential attachment face  154  are perpendicular to the forward edge  130  and the aft edge  134 . In this disclosed non-limiting embodiment, a corner  180  at the interface between the suction side tangential attachment face  152  and the axial attachment face  156  is chamfered. The chamfered corner  180 . The purpose of such a chamfer allows the load bearing faces on the stator shell to clear the edges of the complementary faces&#39; fillet at their junction on the structural platform to prevent contact stress concentration ( FIG. 11 ). 
     In another disclosed non-limiting embodiment, the primary reaction load is parallel to a resultant aerodynamic load from an aerodynamic center as generated by the airfoil and the suction side tangential attachment face  152  is non-parallel to the matefaces  138 A,  138 B ( FIG. 9 ). Notably, the primary and secondary load transmitting faces (alternatively called the axial and tangential faces when these faces are not angled with respect to the engine axis) are always perpendicular to each other, regardless of whether or not one of them is aligned to the resultant loading direction. 
     In another disclosed non-limiting embodiment, the suction side tangential attachment face  152  and the pressure side tangential attachment face  154  are generally parallel to the matefaces  138 A,  138 B of the outer vane endwall  80  ( FIG. 10 ). Such arrangements may facilitate assembly into the engine  20 . 
     The attachment faces  150 ,  152 ,  154 ,  156  enable the use of separate structural platforms for a turbine stator which itself has an airfoil and endwalls while limiting tensile stresses in the plane of the platform. 
     The use of the terms “a,” “an,” “the,” and similar references in the context of description (especially in the context of the following claims) are to be construed to cover both the singular and the plural, unless otherwise indicated herein or specifically contradicted by context. The modifier “about” used in connection with a quantity is inclusive of the stated value and has the meaning dictated by the context (e.g., it includes the degree of error associated with measurement of the particular quantity). All ranges disclosed herein are inclusive of the endpoints, and the endpoints are independently combinable with each other. 
     Although the different non-limiting embodiments have specific illustrated components, the embodiments of this invention are not limited to those particular combinations. It is possible to use some of the components or features from any of the non-limiting embodiments in combination with features or components from any of the other non-limiting embodiments. 
     It should be appreciated that like reference numerals identify corresponding or similar elements throughout the several drawings. It should also be appreciated 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.