STRUT FOR AN AIRCRAFT ENGINE
20180045221 ยท 2018-02-15
Inventors
Cpc classification
F04D29/563
MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
F05D2240/12
MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
F05D2250/00
MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
F04D29/542
MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
F05D2240/14
MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
F04D29/522
MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
Y02T50/60
GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
F01D9/047
MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
F05D2240/128
MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
International classification
F04D29/54
MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
F04D29/56
MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
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.
Claims
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 strut 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 strut 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.
Description
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]
[0013]
[0014]
[0015]
[0016]
[0017]
[0018]
[0019]
[0020]
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]
[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 26A, 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
[0026] It should be appreciated, however, that the exemplary gas turbine engine 10 depicted in
[0027] Referring now to
[0028] As is depicted most clearly in
[0029] Referring still to
[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
[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
[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
[0038] Referring again to
[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 110. 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
[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
[0043] As is depicted in
[0044] Further, for the embodiment depicted, the inner, middle, and outer thicknesses T.sub.I, T.sub.M, T.sub.O 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 T.sub.I, T.sub.M, T.sub.O of the inner, middle, and outer sections 132, 134, 136 respectively, are measured through the midline 142.
[0045] In certain embodiments, the middle thickness T.sub.M of the middle section 134 may be at least about 10% greater than the inner and outer thicknesses T.sub.I, T.sub.O of the inner and outer sections 132, 136. For example, in certain embodiments, the middle thickness T.sub.M of the middle section 134 may be at least about 15% greater than the inner and outer thicknesses T.sub.I, T.sub.O of the inner and outer sections 132, 136. However, in other embodiments, the middle thickness T.sub.M may instead be less than 10% greater than the inner and outer thicknesses T.sub.I, T.sub.O.
[0046] Referring briefly now also to
[0047] Referring again to the spanwise, cross-sectional views of
[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
[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.