WO2018034729A1

WO2018034729A1 - Strut for an aircraft engine

Info

Publication number: WO2018034729A1
Application number: PCT/US2017/037791
Authority: WO
Inventors: Daniel Elmer King; William Edward Cody
Original assignee: General Electric Company
Priority date: 2016-08-15
Filing date: 2017-06-15
Publication date: 2018-02-22
Also published as: CA3033186A1; CN109563743A; US20180045221A1; EP3497306A1

Abstract

A strut for a gas turbine engine includes a body defining a first side and an opposite second side. The first side is spaced from the second side along the circumferential direction of the gas turbine engine. Additionally, the body includes an inner section, a middle section, and an outer section. Each of the inner, middle, and outer sections are arranged in series order along a span of the strut and define a thickness between the first and second sides of the strut. The thickness of the middle section is greater than the thicknesses of the inner section and of the outer section to increase the strut's resistance to buckling in response to forces exerted thereon.

Description

STRUT FOR AN AIRCRAFT ENGINE

FEDERALLY SPONSORED RESEARCH

[0001] This invention was made with government support under contract number FA8650- 09-D-2922 of the U.S. Air Force. The government may have certain rights in the invention.

FIELD OF THE INVENTION [0002] The present subject matter relates generally to a strut for an aircraft engine.

BACKGROUND OF THE INVENTION

[0003] A gas turbine engine includes a fan section and a core engine. The core engine includes serial axial flow relationship, a high pressure compressor to compress an airflow entering the core engine, a combustor in which a mixture of fuel and the compressed air is burned to generate a propulsive gas flow, and a high pressure turbine which is rotated by the propulsive gas flow and which is connected by a shaft to drive the high pressure compressor. A typical bypass turbofan engine adds a low pressure turbine aft of the high pressure turbine which drives a fan of the fan section located forward of the high pressure compressor. A splitter aft of the fan divides fan flow exiting the fan into core engine flow and bypass flow around the core engine.

[0004] The fan section includes one or more stages of fan rotor blades and a strut assembly. The strut assembly includes circumferentially spaced struts mounted to a hub at radially inner ends and to an assembly outer case at radially outer ends. The outer case defines a circular shape, such that a circular flowpath surface is defined for a flowpath through the fan section.

[0005] The struts of the strut assembly must be capable of withstanding relatively large forces generated during operation of the gas turbine engine. These forces may include static forces from a weight of the various components of the gas turbine engine, as well as dynamic forces generated during, e.g., in certain maneuvers of an aircraft including the gas turbine engine. During operation of the gas turbine engine, these forces can urge the struts to buckle. The struts are typically formed in a thick and relatively robust manner in order to withstand the static and dynamic forces. However, such may lead to relatively heavy struts for the strut assembly.

[0006] Accordingly, a strut better able to withstand the static and dynamic forces would be useful. Moreover, a strut better able to withstand the static and dynamic forces, while reducing an overall weight of the strut, would be particularly beneficial.

BRIEF DESCRIPTION OF THE INVENTION

[0007] Aspects and advantages of the invention will be set forth in part in the following description, or may be obvious from the description, or may be learned through practice of the invention.

[0008] In one exemplary embodiment of the present disclosure, a strut is provided for a gas turbine engine defining a circumferential direction. The strut defines a span and includes a body defining a first side and an opposite second side. The first side is spaced from the second side along the circumferential direction. The body includes an inner section, a middle section, and an outer section arranged in series order along the span of the strut. The inner section, middle section, and outer section each define a thickness between the first and second sides. The thickness of the middle section is greater than the thicknesses of the inner section and the outer section.

[0009] In another exemplary embodiment of the present disclosure, a strut assembly is provided for a gas turbine engine defining a circumferential direction. The strut assembly includes an inner hub and an outer structural case. The strut assembly additionally includes a strut extending between the inner hub and the outer structural case. The strut defines a span and a midline extending along the span through a thickest portion of the strut. The strut further defines a first side and an opposite second side, the first side spaced from the second side along the circumferential direction. The strut includes an inner section, a middle section, and an outer section arranged in series order along the span of the strut. The inner section, middle section, and outer section each define a thickness between the first and second sides extending through the midline. The thickness of the middle section is greater than the thicknesses of the inner section and the middle section.

[0010] These and other features, aspects and advantages of the present invention will become better understood with reference to the following description and appended claims. The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

[0011] A full and enabling disclosure of the present invention, including the best mode thereof, directed to one of ordinary skill in the art, is set forth in the specification, which makes reference to the appended figures, in which:

[0012] FIG. 1 is a schematic cross-sectional view of an exemplary gas turbine engine according to various embodiments of the present subject matter.

[0013] FIG. 2 is a close-up, schematic, cross-sectional view of a forward strut assembly, also referred to as a front frame assembly, of the exemplary gas turbine engine of FIG. 1.

[0014] FIG. 3 is an isolated, axial view of the exemplary forward strut assembly of FIG. 2.

[0015] FIG. 4 is a close-up view of a strut attached to an outer structural case of the exemplary forward strut assembly of FIG. 2 in accordance with an exemplary aspect of the present disclosure.

[0016] FIG. 5 is a side view of a strut of the exemplary forward strut assembly of FIG. 2 in accordance with an exemplary aspect of the present disclosure.

[0017] FIG. 6 is a spanwise, cross-sectional view of the exemplary strut of FIG. 5, taken along Line 6-6 of FIG. 5.

[0018] FIG. 7 is a spanwise, cross-sectional view of the exemplary strut of FIG. 5, taken along Line 7-7 of FIG. 5.

[0019] FIG. 8 is a spanwise, cross-sectional view of the exemplary strut of FIG. 5, taken along Line 8-8 of FIG. 5.

[0020] FIG. 9 is a graph charting a thickness of the exemplary strut of FIG. 5 along a midline of the exemplary strut of FIG. 5. DETAILED DESCRIPTION OF THE INVENTION

[0021] Reference will now be made in detail to present embodiments of the invention, one or more examples of which are illustrated in the accompanying drawings. The detailed description uses numerical and letter designations to refer to features in the drawings. Like or similar designations in the drawings and description have been used to refer to like or similar parts of the invention. As used herein, the terms "first", "second", and "third" may be used

interchangeably to distinguish one component from another and are not intended to signify location or importance of the individual components. The terms "upstream" and "downstream" refer to the relative direction with respect to fluid flow in a fluid pathway. For example, "upstream" refers to the direction from which the fluid flows, and "downstream" refers to the direction to which the fluid flows.

[0022] FIG. 1 is a schematic representation of an aircraft gas turbine engine 10 in accordance with one embodiment of the present disclosure. The gas turbine engine 10 defines an axial direction A, a radial direction R, and a circumferential direction C (i.e., a direction extending about the axial direction A, see FIG. 3). The gas turbine engine 10 includes an engine centerline 12 extending along the axial direction A depicted in phantom for reference and has, in serial flow relationship, a fan section 14, a high pressure compressor 16, a combustion section 18, a high pressure turbine 20, and a low pressure turbine 22. The high pressure compressor 16, the combustion section 18 and high pressure turbine 20 are often referred to as a core engine 24.

[0023] The fan section 14 is illustrated as a multi-stage fan section having first, second, and third stage fan blades 26A, 26B, and 26C, respectively, disposed within an annular fan duct 28. The fan section 14 additionally includes a strut assembly supporting at least in part the fan section 14. Specifically, for the embodiment depicted, the fan section 14 includes a forward strut assembly 30 located forward of the first stage fan blades 26A. Additionally, disposed adjacent to each of the first, second, and third stage fan blades 26 A, 26B, and 26C, the fan section 14 includes stages of guide vanes. Specifically, the exemplary fan section 14 depicted includes first stage guide vanes 32A located aft of the first stage fan blades 26A, second stage guide vanes 32B located aft of the second stage fan blades 26B, and third stage guide vanes 32C located aft of the third stage fan blades 26C. The first, second, and third stage guide vanes 32A, 32B, 32C are each disposed around the engine centerline 12, along the circumferential direction C. In certain embodiments, the third stage guide vanes 32C may further be configured as struts. [0024] Fan air 34 exits the fan section 14 and an annular splitter 36 splits the fan air 34 into a bypass air portion 38 bypassed around the core engine 24 through a bypass duct 40 and into a core engine air portion 42 passed through a diffusion duct 44 into the core engine 24. At an aft end of the fan section 14 is a fan frame 46 including a circumferentially disposed plurality of structural struts 48. The struts 48 extend radially across a fan bypass inlet 50 of the bypass duct 40 and a core engine inlet 52 of diffusion duct 44. The splitter 36 is sectioned and attached to the struts 48 and splitter 36 extends axially between the fan bypass inlet 50 and the core engine inlet 52.

[0025] Within the core engine 24, a high pressure rotor shaft 54 connects, in driving relationship, the high pressure turbine 20 to the high pressure compressor 16 and a low pressure rotor shaft 56 drivingly connects the low pressure turbine 22 to the fan section 14. Fuel is burned in the combustion section 18 producing a hot gas flow 58 which is directed through the high pressure and low pressure turbines 20 and 22, respectively, to power the engine 10. The hot gas flow 58 is discharged into an exhaust section 60 of the engine 10 where it is mixed with the bypass air portion 38 from the bypass duct 40 and exhausted through a variable nozzle 62 at the aft end of the engine 10. An afterburner 64 may be used for thrust augmentation. The exemplary engine 10 illustrated in FIG. 1 is typical of a military gas turbine aircraft engine 10, such as the General Electric F-l 10.

[0026] It should be appreciated, however, that the exemplary gas turbine engine 10 depicted in FIG. 1 is provided by way of example only, and in other embodiments of the present disclosure, the gas turbine engine 10 may have any other suitable form or configuration. For example, in other exemplary embodiments, the gas turbine engine 10 may additionally include a low pressure compressor forward of the HP compressor 16 and aft of the fan section 14. Further, in still other embodiments, the gas turbine engine may instead be configured as any other suitable turbofan engine, a turboshaft engine, a turboprop engine, etc.

[0027] Referring now to FIGS. 2 and 3, views are provided of the fan section 14, or more particularly, of the forward strut assembly 30 of the fan section 14 of the exemplary engine 10 of FIG. 1. Specifically, FIG. 2 provides a close-up, side, cross-sectional view of the forward strut assembly 30 of the exemplary fan section 14 depicted in FIG. 1 installed in the engine 10, and FIG. 3 provides an isolated, axial view of the forward strut assembly 30 of the exemplary fan section 14 depicted in FIG. 1. [0028] As is depicted most clearly in FIG. 2, the forward strut assembly 30 supports rotation of the plurality of stages of fan blades 26A, 26B, 26C of the exemplary fan section 14. More particularly, the forward strut assembly 30 includes a plurality of struts 66 extending generally along the radial direction R between an outer structural case 72 and an inner hub 74. For the embodiment depicted, each strut 66 generally includes a body 76 extending between an inner end 78 and an outer end 80, an inner mounting flange 82 formed integrally with the body 76 at the inner end 78 of the body 76, and an outer mounting flange 84 formed integrally with the body 76 at the outer end 80 of the body 76. The inner mounting flange 82 is configured for attachment to the inner hub 74 and the outer mounting flange 84 is configured for attachment to the outer structural case 72. Additionally, the outer structural case 72 of the forward strut assembly 30 is, in turn, configured for attachment to a frame or nacelle (not depicted) of the engine 10. Notably, the exemplary engine 10 depicted also includes a forward seal member 86 for forming a seal with the frame or nacelle of the engine 10.

[0029] Referring still to FIG. 2 in particular, the inner hub 74 of the forward strut assembly 30 is attached to a bearing housing 88. For the embodiment depicted, the inner hub 74 is bolted to the bearing housing 88 through a plurality of bolts 90. The bearing housing 88 encloses a forward fan bearing 92 for supporting a rotor assembly 94 of the fan section 14. As discussed above, the rotor assembly 94 of the fan section 14 may be attached to, or may be an extension of, the LP shaft 56 of the engine 10. In certain embodiments, the forward fan bearing 92 may be configured as a ball bearing, a roller bearing, or any other suitable bearing.

[0030] Moreover, each of the plurality of struts 66 of the forward strut assembly 30 are configured with a guide vane 96. Each of the guide vanes 96 are positioned directly aft of a respective strut 66 and operable with a variable guide vane system 98. The variable guide vane system 98 is configured to rotate each of the plurality of guide vanes 96 about a guide vane axis 100, such that the plurality of guide vanes 96 may direct an airflow entering into the fan section 14 over the forward strut assembly 30 in a desired manner.

[0031] Referring now particularly to FIG. 3, and as will be discussed in greater detail below, the exemplary forward strut assembly 30 depicted includes a plurality of struts 66 formed in a manner to have an increased resistance to buckling. Accordingly, the exemplary forward strut assembly 30 may require fewer struts 66 to support an anticipated amount of force. For example, the exemplary forward strut assembly 30 includes between thirteen (13) and twenty- one (21) struts 66 spaced along the circumferential direction C. Specifically for the embodiment depicted, the forward strut assembly 30 includes thirteen (13) struts 66. However, in other embodiments, the forward strut assembly 30 may instead include any other suitable number of struts 66. In certain embodiments, the plurality of struts 66 may be spaced substantially evenly along the circumferential direction C, or in other embodiments the plurality of struts 66 may be asymmetrically spaced along the circumferential direction C.

[0032] Further, the inner hub 74 defines an inner hub radius 102 and the outer structural case 72 similarly defines an outer structural case radius 104. The inner hub radius 102 and outer structural case radius 104 are each defined along the radial direction R from the axial centerline 12 to a respective mounting surface. More particularly, the inner hub radius 102 is defined along the radial direction R from the axial centerline 12 to a mounting surface 106 of the inner hub 74. Notably, for the embodiment depicted, the mounting surface 106 of the inner hub 74 defines an angle relative to the axial centerline 12 (see FIG. 2). Accordingly, the hub radius 102 is more specifically defined for the embodiment depicted along the radial direction R from the axial centerline 12 to an aft end of the mounting surface 106 of the inner hub 74. Similarly, the outer structural case radius 104 is defined along the radial direction R from the axial centerline 12 to a mounting surface 108 of the outer structural case 72.

[0033] Given that the struts 66 of the exemplary forward strut assembly 30 are capable of withstanding an increased amount of force, fewer struts may be required, meaning that a size of the inner hub 74 may be reduced (as less surface area on the mounting surface 106 is required to mount the struts 66). Accordingly, a ratio of the inner hub radius 102 to the outer structural case radius 104 may also be reduced. For example, for the embodiment depicted, a ratio of the inner hub radius 102 to the outer structural case radius 104 is less than about 1 :4. It should be appreciated, that terms of approximation, such as "about" or "approximately," refer to being within a 10% margin of error.

[0034] For the embodiment depicted, the inner hub 74 of the forward strut assembly 30 defines a substantially circular shape, and accordingly, the mounting surface 106 is also substantially circular. The outer structural case 72 includes a plurality of mounting pads 110 and a plurality of case ligaments 112. Each of the plurality of case ligaments 112 extends between adjacent mounting pads 110, connecting the adjacent mounting pads 110. For the embodiment depicted, each of the plurality of mounting pads 110 and case ligaments 112 extend in a substantially straight direction, such that the outer structural case 72 generally defines a polygonal shape. Accordingly, the mounting surface 108 is also substantially straight. It should be appreciated, however, that in other exemplary embodiments, the outer structural case 72 may instead be configured to define a substantially circular shape. [0035] As used herein, the term "substantially straight" with reference to the plurality of case ligaments 112 refers to the particular case ligament 112 defining a radius of curvature greater than at least two times a radial length of one or more of the plurality of struts 66 of the forward strut assembly 30. Further, the term "substantially straight" may also refer to a case ligament 112 defining a straight reference line extending in a straight direction between the adjacent mounting pads 110 (between which the case ligament 112 extends) completely enclosed within the case ligament 112.

[0036] As briefly discussed above, each of the plurality of struts 66 includes an inner mounting flange 82 attaching the respective strut 66 to the inner hub 74 and an outer mounting flange 84 attaching the respective strut 66 to the outer structural case 72. More particularly, the outer mounting flange 84 of each respective strut 66 attaches the strut 66 to a respective mounting pad 110 of the outer structural case 72.

[0037] Referring now briefly also to FIG. 4, a close-up view is provided of an outer mounting flange 84 of a strut 66 of the plurality of struts 66 attached to a mounting pad 110 of the outer structural case 72. For the embodiment depicted, the outer mounting flange 84 of the plurality of struts 66 is configured as a T-shaped flange. As noted, the outer mounting flange 84, configured for the embodiment depicted as a T-shaped flange, is formed integrally with the body 76 of the strut 66 at the outer end 80 of the strut 66. The T-shaped mounting flange includes oppositely extending projections 114 for mounting the strut 66. Specifically, the strut assembly 30 includes mounting brackets/plates 116 positioned opposite the respective mounting pads 110 of the T-shaped flanges and mounting plates 118 positioned on an inner surface of the oppositely extending projections 114. For the embodiment depicted, bolts 120 extend from the mounting brackets 116, through the respective mounting pad 110, through the oppositely extending projections 114, and to the mounting plates 118. It should be appreciated, that for the

embodiment depicted, the outwardly extending projections 114 each define a thickness Tp. The thickness Tp is defined generally along the radial direction R. Additionally, for the exemplary strut assembly 30 described herein, each of the plurality of struts 66 includes an outer mounting flange 84 configured as a T-shaped flange attaching the strut 66 to a respective mounting pad 110 and a similar manner.

[0038] Referring again to FIG. 3, for the embodiment depicted the plurality of mounting pads 110 and case ligaments 112 are formed integrally of a composite material. For example, in certain embodiments, each of the plurality of mounting pads 110 and case ligaments 112 may be formed of a carbon fiber reinforced composite material, or any other suitable composite material. [0039] Additionally, each of the plurality of case ligaments 112 defines an inner surface 122 along the radial direction R (i.e., a radially inner surface), which as will be discussed below extends axially and circumferentially as well. Given that for the embodiment depicted each of the plurality of case ligaments 112 extend in a substantially straight direction between adjacent mounting pads 110, the radially inner surfaces 106 of the case ligaments 112 together define a non-circular shape (i.e., a polygonal shape) as viewed along the axial direction A. In order to allow for the outer structural case 72 to define a flowpath surface 124 (i.e., an inner radial surface of the outer structural case 72 as a whole, defining a flowpath through the fan section 14) that more closely resembles a circle for aerodynamic purposes, the forward strut assembly 30 further includes a plurality of wedge members 126 positioned along the inner surfaces 106 of the case ligaments 112, adjacent to the mounting pads 1 10. For certain exemplary embodiments, each of the plurality of wedge members 126 may extend a variety of lengths (such as between thirty percent and fifty percent of a length of the case ligament 112, i.e., a distance between adjacent mounting pads 110, adjacent to which it is positioned). Notably, the lengths of the wedge members 126 may vary as a function of a spacing of the struts 66, which may be spaced between 24° or 30° apart, and may have two or more different spacing angles between struts 66.

[0040] Referring now to FIG. 5, an isolated, side view of a single strut 66 of the exemplary forward strut assembly 30 described above with reference to FIGS. 2 through 4 is provided. The strut 66 defines a span S extending along a length of the strut 66, as shown. Additionally, as previously discussed, the strut 66 includes a body 76 defining an inner end 78 and an outer end 80, an outer mounting flange 84 formed integrally with the body 76 at the outer end 80 of the body 76, and an inner mounting flange 82 formed integrally with the body 76 at the inner end 78 of the body 76. As is also depicted, the body 76 of the strut 66 defines a forward end 128 and an aft end 130. The exemplary strut 66 depicted is operable with a guide vane 96 at the aft end 130 (see FIG. 2).

[0041] Moreover, the body 76 of the strut 66 includes an inner section 132, a middle section 134, and an outer section 136 arranged in series order along the span S of the strut 66. For the embodiment depicted, the inner section 132 includes approximately an inner thirty percent (30%) of the span S of the strut 66, the middle section 134 includes approximately a middle forty percent (40%) of the span S of the strut 66, and the outer section 136 includes approximately an outer thirty percent (30%) of the span S of the strut 66.

[0042] Reference will now also be made to FIGS. 6 through 8. FIG. 6 provides a spanwise, cross-sectional view of the body 76 of the strut 66 along Line 6-6 in FIG. 5; FIG. 7 provides a spanwise, cross-sectional view of the body 76 of the strut 66 along Line 7-7 in FIG. 5; and FIG. 8 provides a spanwise, cross-sectional view of the body 76 of the strut 66 along Line 8-8 in FIG. 5. More particularly, FIG. 6 provides a spanwise, cross-sectional view of the outer section 136 of the body 76 of the strut 66, FIG. 7 provides a spanwise, cross-sectional view of the middle section 134 of the body 76 of the strut 66, and FIG. 8 provides a spanwise, cross-sectional view of the inner section 132 of the body 76 of the strut 66.

[0043] As is depicted in FIGS. 6 through 8, the body 76 of the strut 66 further defines a first side 138 and an opposite second side 140, the first side 138 spaced from the second side 140 along the circumferential direction C (see FIG. 3) of the gas turbine engine 10. Additionally, the outer section 136 defines an outer thickness To between the first and second sides 138, 140, the middle section 134 defines a middle thickness TM between the first and second sides 138, 140, and the inner section 132 defines an inner thickness Ti between the first and second sides 138, 140. The middle thickness TM of the middle section 134 is greater than the outer and inner thicknesses To, Ti of the outer and inner sections 136, 132 to increase a load capacity of the strut 66. Accordingly, the strut 66 depicted in FIGS. 5 through 8 includes a greater mid-span thickness.

[0044] Further, for the embodiment depicted, the inner, middle, and outer thicknesses Ti, TM, To are measured proximate the aft end 130 of the body 76 of the strut 66 (i.e., closer to the aft end 130 than the forward end 128). More specifically, the body 76 defines a midline 142 extending from the inner end 78 to the outer end 80 and along the span S. The midline 142 extends through a thickest portion of the body 76 of the strut 66. For the embodiment depicted, the inner, middle, and outer thicknesses Ti, TM, To of the inner, middle, and outer sections 132, 134, 136 respectively, are measured through the midline 142.

[0045] In certain embodiments, the middle thickness TM of the middle section 134 may be at least about 10% greater than the inner and outer thicknesses Ti, To of the inner and outer sections 132, 136. For example, in certain embodiments, the middle thickness TM of the middle section 134 may be at least about 15% greater than the inner and outer thicknesses Ti, To of the inner and outer sections 132, 136. However, in other embodiments, the middle thickness TM may instead be less than 10% greater than the inner and outer thicknesses Ti, To.

[0046] Referring briefly now also to FIG. 9, a chart is provided graphing a thickness of the body 76 of the strut 66 through the midline 142 and along the span S of the strut 66. As is depicted, the inner thickness Ti of the inner section 132 is a minimum thickness of the inner section 132 measured through the midline 142, the outer thickness To of the outer section 136 is similarly a minimum thickness of the outer section 136 measured through the midline 142, and the thickness of the middle section 134 is a maximum thickness of the middle section 134 measured through the midline 142. As is also shown by the chart in FIG. 9, for the embodiment depicted a thickness through the midline 142 of the body 76 of the strut 66 increases at the inner end 78 from the inner thickness Ti and at the outer end 80 from the outer thickness To. Such an increase in thickness may be to provide greater strength and stability at the inner and outer mounting flanges 82, 84, respectively.

[0047] Referring again to the spanwise, cross-sectional views of FIGS. 6 through 8, for the embodiment depicted the body 76 of the strut 66 defines, for the embodiment depicted, a hollow cavity 144 between the first side 138 and second side 140. The hollow cavity 144 extends within the body 76 substantially from the inner end 78 of the body 76 to the outer end 80 of the body 76. The hollow cavity 144 is positioned forward of the midline 142, such that the hollow cavity 144 may reduce a weight of the strut 66, without significantly reducing a strength of the strut 66, or more particularly, without significantly reducing a resistance of the strut 66 to buckling forces. It should be appreciated, however, that in other embodiments, the strut 66 may not define the cavity 144.

[0048] Notably, as with the outer structural case 72, the strut 66 may be formed of a composite material. For example, the strut 66 may be formed of a carbon fiber reinforced material. Alternatively, however, in other embodiments, the strut 66 may be formed of any other suitable composite material. As the strut 66 may be formed of a composite material, the plies or layers forming the strut 66 may be split at the inner and outer ends 78, 80 of the body 76 to form the inner and outer mounting flanges 82, 84. Accordingly, as noted above with reference to FIG. 4, the oppositely extending projections 114 of the outer mounting flange 84 (i.e., configured as a T-shaped mounting flange) define a thickness Tp. The thickness Tp of the oppositely extending projections 114 are for the embodiment depicted less than or equal to about half of the outer thickness To of the outer section 136 of the body 76. However, in other exemplary embodiments, the outer mounting flange 84 may be formed in any other suitable manner to include projections 114 having any other suitable thickness To.

[0049] Inclusion of a strut assembly having a strut formed in accordance with one or more the present embodiments may allow for a stronger strut more resistant to buckling forces.

Specifically, as will be appreciated, inclusion of a greater mid-span thickness increase a resistance of the strut to buckling. At the same time, forming a strut in accordance with one or more of the present embodiments of a composite material may also reduce a weight of the strut and of a corresponding strut assembly.

[0050] This written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they include structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal languages of the claims.

Claims

WHAT IS CLAIMED IS:

1. A strut for a gas turbine engine defining a circumferential direction, the strut defining a span and comprising: a body defining a first side and an opposite second side, the first side spaced from the second side along the circumferential direction, the body comprising an inner section, a middle section, and an outer section arranged in series order along the span of the strut, the inner section, middle section, and outer section each defining a thickness between the first and second sides, the thickness of the middle section being greater than the thicknesses of the inner section and the outer section.

2. The strut of claim 1, wherein the strut is formed of a composite material.

3. The strut of claim 1, wherein the thickness of middle section is at least about ten percent (10%) greater than the thicknesses of the inner section and of the outer section.

4. The strut of claim 1, wherein the thickness of middle section is at least about fifteen percent (15%) greater than the thicknesses of the inner section and of the middle section.

5. The strut of claim 1, wherein the inner section comprises an inner thirty percent of the span of the strut, wherein the middle section comprises a middle forty percent of the span of the strut, and wherein the outer section comprises the outer thirty percent of the span of the strut.

6. The strut of claim 1, wherein the thicknesses of the inner section, middle section, and outer section are each measured proximate the aft end of the strut.

7. The strut of claim 1, wherein the body defines an inner end and an outer end, wherein the strut defines a midline extending from the inner end to the outer end through a thickest portion of the body, and wherein the thicknesses of the inner section, middle section, and outer section are measured through the midline.

8. The strut of claim 7, wherein the thickness of the inner section is a minimum thicknesses of the inner section, wherein the thickness of the outer section is a minimum thicknesses of the outer section, and wherein the thickness of the middle section is the maximum thickness of the middle section.

9. The strut of claim 1, wherein the body defines a hollow cavity between the first surface and the second surface extending substantially from the inner end to the outer end.

10. The stmt of claim 1, wherein the body defines an inner end and an outer end, wherein the strut further comprises an outer T-shaped mounting flange formed integrally with the body at the outer end of the body.

11. The strut of claim 10, wherein the T-shaped mounting flange comprises oppositely extending projections for mounting the strut, wherein the oppositely extending projections define a thickness, and wherein the thickness of the oppositely extending projections is less than or equal to about half of the thickness of the outer section.

12. A strut assembly for a gas turbine engine defining a circumferential direction, the strut assembly comprising: an inner hub; an outer structural case; and a strut extending between the inner hub and the outer structural case, the strut defining a span and a midline extending along the span through a thickest portion of the strut, the strut further defining a first side and an opposite second side, the first side spaced from the second side along the circumferential direction, the strut comprising an inner section, a middle section, and an outer section arranged in series order along the span of the strut, the inner section, middle section, and outer section each defining a thickness between the first and second sides extending through the midline, the thickness of the middle section being greater than the thicknesses of the inner section and the middle section.

13. The strut assembly of claim 12, wherein the body defines an inner end and an outer end, wherein the midline extends from the inner end to the outer end.

14. The strut assembly of claim 12 wherein the thickness of the inner section is a minimum thicknesses of the inner section, wherein the thickness of the outer section is a minimum thicknesses of the outer section, and wherein the thickness of the middle section is the maximum thickness of the middle section.

15. The strut assembly of claim 12, wherein the thickness of middle section is at least about 10% greater than the thicknesses of the inner section and of the middle section.

16. The strut assembly of claim 12, wherein the body defines an inner end and an outer end, wherein the body comprises an outer T-shaped mounting flange at the outer end.

17. The stmt assembly of claim 16, wherein the T-shaped mounting flange comprises oppositely extending projections for mounting the strut, wherein the oppositely extending projections define a thickness, and wherein the thickness of the oppositely extending projections is about half of the thickness of the outer section.

18. The strut assembly of claim 12, wherein the strut assembly is a forward strut assembly for a fan section of the gas turbine engine.

19. The strut assembly of claim 12, wherein the strut comprises a plurality of struts, wherein the plurality of struts includes between thirteen and twenty-one struts.

20. The strut assembly of claim 12, wherein the strut assembly defines an inner hub radius and an outer structural case radius, and wherein a ratio of the inner hub radius to the outer structural case radius is less than about 1 :4.