Inlet bulkhead for large diameter aircraft engines

Abstract

An inlet bulkhead for a large diameter aircraft engine is provided. In certain instances, the inlet bulkhead includes an annular body having an outer flange, an inner flange, and a web having a first side and an opposite second side. The web extends from the outer flange to the inner flange. The bulkhead further includes at least one annular stiffener disposed on the first side and a plurality of radial stiffeners disposed on the first side, each stiffener extending from the outer flange to the inner flange. The annular stiffeners and the radial stiffeners can be integrally formed with the web.

Description

TECHNICAL FIELD

[0001] The present disclosure relates generally to aircraft engine nacelles, and more particularly to aircraft engine nacelle inlets having at least one bulkhead. BACKGROUND

[0002] Aircraft engines, such as turbojet and turbofan engines, are typically surrounded by a barrel-shaped nacelle. The nacelle inlet is typically formed with an outer wall that is airfoil shaped and an inner wall that defines an inlet of the engine. The outer wall and the inner wall define a cavity therebetween that houses a forward bulkhead and an aft bulkhead. Very high bypass ratio jet engines result in larger diameter nacelle inlets with greater wetted area, which can result in higher reaction internal loads and displacements compared to smaller diameter engines. The forward and aft bulkheads are important structural elements that counteract loads caused by aerodynamic and cavity pressure, thermal variations, and fan blade events during engine operation. Current bulkheads utilize thicker structural webs to provide stiffness and strength capable of handling the higher loads and displacements of very high bypass ratio engines. However, the added weight can compromise the overall performance of the aircraft. SUMMARY

[0003] The subject matter of the present application has arisen in response to the current state of the art, and more specifically, in response to the shortcomings of conventional bulkheads that have not been completely solved by the technology currently available. Accordingly, the subject matter of the present application has arisen in an effort to provide an apparatus, system, and method that overcomes at least some of the aforementioned shortcomings of the prior art.

[0004] In certain embodiments, the system includes an engine nacelle inlet having an outer barrel, an inner barrel, a forward bulkhead, and an aft bulkhead. The forward bulkhead includes an outer flange joined to a surface of the outer barrel, an inner flange joined to a surface of the inner barrel, a web connecting the outer flange to the inner flange, and at least one annular stiffener extending from the web and between the inner flange and the outer flange.

[0005] In certain embodiments, the aft bulkhead includes an outer flange joined to a surface of the outer barrel, an inner flange joined to a surface of the inner barrel, a web connecting the outer flange to the inner flange, and at least one annular stiffener extending from the web and between the inner flange and the outer flange. The ratio of the web height to the web thickness of the forward bulkhead can be between about 255 and 380. In certain embodiments, the web thickness is greater than or equal to 0.0450 inches and the web height is less than or equal to 17.0 inches.

[0006] In certain embodiments, the ratio of the web height to the web thickness of the aft bulkhead is between about 210 and 410. The web thickness of the aft bulkhead is greater than or equal to 0.0450 inches and the web height of the aft bulkhead is less than or equal to 20.0 inches. In certain embodiments, the forward bulkhead also includes radial stiffeners that are integrally formed with the web and extend from the outer flange to the inner flange. In certain embodiments, each radial stiffener intersects at least one annular stiffener.

[0007] In certain embodiments, the forward bulkhead includes a plurality of annular stiffeners, each annular stiffener having a unique diameter. Each of a pair of adjacent radial stiffeners intersects an adjacent annular stiffener to form a cell that is capable of elastically compressive buckling under all flight loads without exceeding the fatigue load.

[0008] In certain embodiments, the aft bulkhead, like the forward bulkhead, includes a plurality of radial stiffeners that are integrally formed with the web and each extends from the outer flange to the inner flange. The radial stiffeners of the aft bulkhead can also intersect at least one annular stiffener. In certain embodiments, the aft bulkhead includes a plurality of annular stiffeners, each annular stiffener having a unique diameter. A pair of radial stiffeners can intersect an adjacent annular stiffener to form a cell that is capable of elastically compressive buckling under all flight loads without exceeding the fatigue load.

[0009] Apparatuses of the present disclosure are also described below. In certain embodiments, the apparatus includes an annular body having an outer flange, an inner flange, and a web having a first side and an opposite second side, the web extending from the outer flange to the inner flange. The apparatus also includes at least one annular stiffener disposed on the first side and a plurality of radial stiffeners disposed on the first side, each stiffener extending from the outer flange to the inner flange.

[0010] In certain embodiments, the annular stiffeners are integrally formed with the web and each radial stiffener is integrally formed with the web. The apparatus can include a plurality of annular stiffeners, each annular stiffener having a unique diameter. A pair of adjacent radial stiffeners can intersect a pair of adjacent annular stiffeners to form a cell that is capable of elastically compressive buckling under all flight loads without exceeding the fatigue load. The ratio of the web height to the web thickness of the apparatus can be in a range of about 210 and 410. In certain embodiments, the web height is less than or equal to 20.0 inches and the web thickness is greater than or equal to 0.0450 inches.

[0011] Methods of the present disclosure include forming an annular web surface having an inner flange and an outer flange, and forming at least one annular stiffener on a side of the annular web surface. The method also includes forming a radial stiffener on a side of the annular web surface.

[0012] The described features, structures, benefits and / or characteristics of the disclosed subject matter can be combined in any suitable manner in one or more instances and / or embodiments. In the following description, numerous specific details are provided to provide a thorough understanding of examples of the disclosed subject matter. One having ordinary skill in the relevant art will recognize that the disclosed subject matter can be practiced without one or more of the specific details, in instances, and / or specific features, components, materials, and / or methods described below. In other instances, additional features and advantages can be recognized in certain examples and / or implementations from the following description. Further, it will be apparent that the described subject matter is not limited to the specific examples described below, but includes all alternatives, modifications, and equivalents falling within the scope of the disclosed subject matter as defined by the appended claims. The features, benefits and / or advantages of the disclosed subject matter will become apparent to one of ordinary skill in the art upon reading the details hereinafter which follows and reviewing the associated drawings. BRIEF DESCRIPTION OF DRAWINGS

[0013] In order that the advantages of the subject matter will be more readily understood, a more particular description of the subject matter, briefly described above, will be rendered by reference to specific examples that are illustrated in the appended drawings. These drawings depict only typical examples of the subject matter and are therefore not to be considered limiting of its scope, the subject matter being set forth in the claims. The subject matter will be described and explained with additional specificity and detail by the use of the accompanying drawings in which:

[0014] Figure 1 is a diagram illustrating a partial cross-sectional view of a pod entrance according to an example of the present disclosure;

[0015] Figure 2 is a perspective view illustrating a rear side of a front bulkhead according to an example of the present disclosure;

[0016] Figure 3 is another perspective view of a front side of a front bulkhead according to an example of the present disclosure;

[0017] Figure 4 is a partial elevational view illustrating a portion of a rear side of a front bulkhead according to an example of the present disclosure;

[0018] Figure 5 is a cross-sectional view illustrating important features of a front bulkhead according to an example of the present disclosure;

[0019] Figure 6 is a perspective view illustrating a rear side of a rear bulkhead according to an example of the present disclosure;

[0020] Figure 7 is another perspective view of a front side of a rear bulkhead according to an example of the present disclosure;

[0021] Figure 8is a partial normal view diagram illustrating a portion of a rear bulkhead according to an example of the present disclosure;

[0022] Figure 9 is a flow diagram illustrating a method for providing a front or rear bulkhead according to an example of the present disclosure;

[0023] Figure 10 is a cross-sectional view diagram illustrating another embodiment of a front bulkhead according to an example of the present disclosure; and

[0024] Figure 11 is a cross-sectional view diagram illustrating another embodiment of a rear bulkhead according to an example of the present disclosure. DETAILED DESCRIPTION

[0025] Throughout this specification, reference can be made to "an example", "one example", or similar language. This does not necessarily refer to the same example throughout the specification. Likewise, the term "implementation" is used to mean an implementation having or incorporating the particular feature(s), structure(s), or characteristic(s) being referred to. However, it is also possible that the implementation could be one of a plurality of similar implementations that differ from one another by e.g. at least the particular feature(s), structure(s) or characteristic(s) being referred to. Throughout the description, like reference numbers refer to like elements throughout.

[0026] The apparatus and methods of the present disclosure provide nacelle inlet bulkheads having annular or hoop-shaped stiffeners intersecting with radially extending stiffeners. In a configuration, each bulkhead is annular having an inner diameter formed by an inner flange and an outer diameter formed by an outer flange. The intersection of the annular and radial stiffeners defines a cell therebetween having an annular sector (i.e. a torus sector) shape. A web extends between the annular stiffener and the radial stiffener. This arrangement enables a thinner web thickness (in some cases approaching a minimum manufacturing thickness) that, while reducing the overall nacelle inlet weight, also handles operational flight loads and, in some cases, safely buckles in a controlled manner without failure. This arrangement also improves damage tolerance for fan blade out and bird strike events and improves ovalization stiffness of the inlet. Higher ovalization stiffness helps the fan case maintain a clearance of the fan blade tips. The front and rear stiffness of this arrangement is equal to or better than the current state of the art, which increases the natural frequency, which is beneficial in high vibration environments. These benefits and features are described in more detail below.

[0027] Figure 1is a drawing showing a partial cross-sectional view of a nacelle inlet 100 according to an example of the present disclosure. The nacelle inlet 100 encloses a turbofan engine (partially shown) for an aircraft. However, it is contemplated that the present disclosure is equally applicable to other types of engines and nacelles of vehicles. Additionally, features of the bulkheads described below can be incorporated into other structural components of vehicles that would benefit from an increase in structural stiffness provided by a cavity disposed between an inner and outer load receiving surface.

[0028] In certain examples, the nacelle inlet 100 extends generally circumferentially about a centerline 102. The lip skin assembly 104 includes a lip skin segment 106 extending from a first lip skin edge 108 to a hilite 110 to define a generally diffuser-shaped inlet 112 of the nacelle inlet, while continuing to a second lip skin edge 113. As such, the lip skin segment 106 forms at least a portion of an inner wall on an interior 114 of the nacelle inlet 100 and at least a portion of an outer wall 122 of the nacelle inlet 100. The lip skin assembly 104 includes an outer barrel segment 120 extending from the lip skin edge 113 to a second edge 118 to form at least a portion of the outer wall 122 of the nacelle inlet 100. In an alternative example, the lip skin assembly 104 includes an outer barrel segment 120 extending from a lip skin edge 123 to the second edge 118. In this alternative example, the lip skin 106 extends from the edge 108 to 123.

[0029] A radially inner barrel 124 extends from a first inner barrel edge 126 proximate the first lip skin edge 108 to a second inner barrel edge 128. The inner barrel 124 is disposed proximate an airflow 130 that enters through the inlet 112 and flows generally in a downstream direction 132 when the nacelle inlet 100 is operable. The inner barrel 124 and the lip skin assembly 104 are joined in any suitable manner that enables the nacelle inlet 100 to function as intended. The inner barrel 124 encloses fan blades 129 of the turbofan engine and has a diameter selected to accommodate a fan case assembly 131. In certain examples, the diameter of the inner barrel 124 is greater than or equal to 100 inches.

[0030] In certain examples, a forward bulkhead 134 extends radially between an inner wall such as the first lip skin edge 108 and inner barrel edge 126 and an outer wall such as the lip skin segment 106. The forward bulkhead 134 extends between the inner and outer lip skin segments 106 to form a D-shaped duct plenum 136. In alternative examples, where the lip skin and outer barrel edge are located on the edge 123, the forward bulkhead 134 can extend between the lip skin edge 108 and inner barrel edge 126 and the two lip skin segments 106 and outer barrel segment 120 at the edge 123. The D-shaped duct plenum 136 is an annular plenum extending around the nacelle inlet 100 and is configured to direct a flow of heated air received by an anti-icing system (not shown). The heated air is configured to sufficiently heat the lip skin assembly 104 to prevent ice crystals from forming on the nacelle inlet 100.

[0031] In certain examples, the nacelle inlet 100 includes a rear bulkhead 138 extending from the inner barrel 124 to the outer barrel 120 and can be disposed proximate the second inner barrel edge 128. The rear bulkhead 138 is spaced axially along the centerline 102 from the forward bulkhead 134 to define a second plenum 140 therebetween, which is radially bounded by the lip skin 106 and the outer barrel 120 and inner barrel 124, and in the alternative, only the outer barrel 120 and inner barrel 124. Alternatively, the forward and rear bulkheads 134, 138 are positioned at any suitable location enabling the nacelle inlet 100 to function properly.

[0032] Figure 2 is a perspective view illustrating one embodiment of a forward bulkhead 134 according to examples of the present disclosure. As described above, the forward bulkhead 134 forms an annular wall between the D-shaped duct plenum 136 and the second plenum 140. The forward bulkhead 134 includes an inner flange 202 defining an inner diameter and an outer flange 204 defining an outer diameter. The inner and outer flanges 202, 204 are joined to the inner barrel 124 (and / or lip skin segment) at the lip skin edge 108 and to the lip skin outer segment at the edge 123 (and in the alternative, the outer barrel 120). The forward bulkhead 134 is configured to operate under tensile, compressive, and shear forces, as well as bending moments, as a result of aerodynamic loads on the outer surface 122, pressurization and thermal loads from the D-shaped duct plenum 136 of the anti-icing system, pressurization of the rear bulkhead 138, and the surrounding thermal environment, depending on the flight conditions.

[0033] In certain examples, the front bulkhead 134 is a monolithic structure. Alternatively, the front bulkhead 134 can be formed from an annular segment or multiple annular sectors. In certain examples, the front bulkhead 134 is machined with one or more annular stiffeners 206. Each annular stiffener 206 is formed on a web surface 208 that extends between the inner flange 202 and the outer flange 204. Each annular stiffener 206 can be integrally formed with the web surface 208.

[0034] Depending on the web height (i.e., the radial distance between the inner flange 202 and the outer flange 204), the front bulkhead can be configured with two annular stiffeners 206, as shown. Alternatively, the front bulkhead 134 can be configured with a single annular stiffener 206 or three or more annular stiffeners 206. The annular stiffeners 206 can be equally spaced or offset in the radial direction between the inner flange 202 and the outer flange 204. In some implementations, the front bulkhead 134 is formed with the annular stiffeners 206 on a rear-facing surface to provide a smooth surface for the de-icing system and blanket.

[0035] In certain examples, the front bulkhead 134 is formed with one or more radial stiffeners 210 that extend radially from the inner flange 202 to the outer flange 204. The radial stiffeners 210 can be formed on the same side of the web surface 208 as the annular stiffeners 206, as shown. Each radial stiffener 210 can be integrally formed with the web surface 208. As will be described in more detail below, the radial stiffeners 210 intersect the annular stiffeners 206 and define cells or compartments in the general shape of an annulus sector. Figure 4 As will be described in more detail below, the radial stiffeners 210 intersect the annular stiffeners 206 and define cells or compartments in the general shape of an annulus sector.

[0036] The front bulkhead 134 can be formed with accessory openings 212 to allow passage of accessories from the D-shaped duct plenum 136 to the second plenum 140 / to allow passage of accessories from the second plenum 140 to the D-shaped duct plenum 136. Examples include, but are not limited to, air paths that carry heated air streams from the de-icing system.

[0037] Figure 3 is another perspective view of the front bulkhead 134 according to examples of the present disclosure. The depicted implementation shows the opposite surface of the web 208 from the above with respect to Figure 2 In certain examples, the front bulkhead 134 can be oriented such that the smooth web surface 302 faces the hilite 110 of the lip skin assembly 104 to facilitate smooth flow of heated air within the D-shaped duct plenum 136 for the de-icing system. The front bulkhead 134 can have a generally conical flattened body, as shown, or alternatively, a generally planar body or a concave body.

[0038] During operation, the front bulkhead 134 is configured to receive impact loads and still be able to maintain residual strength using both circumferential and radial load paths from the annular and radial stiffeners, respectively. In other words, the grid pattern of stiffeners provides multiple redundant load paths around a locally damaged area. For example, if there is a bird strike, the lip skin can be ruptured, exposing the front bulkhead to some impact energy. The front bulkhead 134 is configured to withstand the damage and maintain residual strength to allow for a safe landing of the aircraft. The web surface 208 can be ruptured while absorbing the impact forces. The annular stiffeners 206 and the radial stiffeners 210 can act as crack arrestors to limit extensive damage to maintain the structural stiffness and residual strength of the front bulkhead 134 after an impact event.

[0039] Figure 4 is a partial elevation view illustrating a portion of the back side of the front bulkhead 134 according to an example of the present disclosure. As described above, the front bulkhead 134 is formed with one or more annular stiffeners 206 joined to the web surface 208 and proximate to a minimum manufacturing gauge and one or more radial stiffeners 210 intersecting the annular stiffeners 206. The intersection of the annular stiffeners 206 and the radial stiffeners define the boundaries of a cell 402 or a compartment. In certain examples, the cell 402 is formed to have a generally annular sector shape. As known to those skilled in the art, an annular sector or ring sector is a portion of a ring formed by two lines extending radially from the center of the ring. In this example, the cell 402 is defined by a pair of adjacent radially extending stiffeners 210 and an adjacent annular stiffener 206 or annular stiffener 206 and an adjacent flange (e.g., inner flange 202 or outer flange 204). By customizing the compartment size indicative of buckling behavior, the cell 402 is designed to be as close to the minimum manufacturing gauge as possible.

[0040] As shown, the cells 402 are configured to undergo a compressive buckling under a predetermined load and return to their pre-buckled shape (elastic buckling). Loads that can result in an elastic compressive buckling event include all flight loads that do not exceed the fatigue loads (i.e., the flight load level encountered once every two flights with the de-icing system turned off).

[0041] Figure 5 is a cross-sectional view illustrating another embodiment of the front bulkhead 134 according to an example of the present disclosure. The depicted embodiment shows the upper half of the cross-sectional view, as Figure 1The front bulkhead 134 is formed from an inner flange 202, an outer flange 204, and a web 208 joining the inner flange 202 to the outer flange 204. As described above, the front bulkhead 134 is formed in a generally I-beam configuration. The rear bulkhead 138 is also formed in a generally I-beam configuration. However, the rear bulkhead 138 can include stiffeners (radial and / or annular) on both sides of the web, as depicted by stiffeners 206 in dashed lines.

[0042] One or more annular stiffeners 206 are disposed on the surface of the web 208. Radial stiffeners 210 are not shown here. In certain examples, the web 208 has a thickness 502 in a range between about 0.030 and 0.055. In further embodiments, the thickness 502 of the web 208 is in a range between about 0.045 and 0.050. Although depicted as having a uniform thickness 502, the thickness can increase or decrease along the web height 504 from the outer flange 204 to the inner flange 202.

[0043] The cell height 506 or radial distance between adjacent annular stiffeners 206 can be substantially uniform across all cells 402 of the front and / or rear bulkhead. Alternatively, the spacing between annular stiffeners 206 can vary. Although described in a general I-beam configuration, many other configurations are contemplated, including but not limited to the configurations described above with reference to FIGS. 2A-2C. Figures 1 to 4 The depicted configuration. The discussion of the web, as well as the height and thickness of the cells, generally applies to the rear bulkhead 138, which is described in more detail below with reference to Figures 6 to 8 FIG. 3.

[0044] Figure 6 is a perspective view showing one embodiment of a rear bulkhead 138 according to an example of the present disclosure. The rear bulkhead 138 is an annular barrier that extends outward from the inner barrel 124 of the gondola portal 100 to the outer barrel 120. The rear bulkhead 138 is formed with an inner flange 602 and an outer flange 604 in a manner similar to the front bulkhead 134. The inner flange 602 is coupled to the rear bulkhead 138 and engages the inner barrel 124. The outer flange 604 is coupled to the rear bulkhead 138 and engages the outer barrel 120 of the gondola portal 100.

[0045] In certain examples, the rear bulkhead 138 is a monolithic structure. Alternatively, the rear bulkhead 138 can be formed from annular segments (i.e., a plurality of concentric rings of increasing diameter to form the bulkhead 138) or a plurality of annular sectors. In certain examples, the rear bulkhead 138 is formed with one or more annular stiffeners 606. Each annular stiffener 606 is formed on a web surface 607 that extends between the inner flange 602 and the outer flange 604. In certain embodiments, each annular stiffener 606 is integrally formed with the web surface 607.

[0046] Depending on the web height (i.e., the radial distance between the inner flange 602 and the outer flange 604), the aft bulkhead 138 can be configured with two annular stiffeners 606, as shown. Alternatively, the aft bulkhead 138 can be configured with a single annular stiffener 606 or three or more annular stiffeners 606. The annular stiffeners 606 can be equally spaced between the inner flange 602 and the outer flange 604. In other words, the annular regions formed between the annular stiffeners 606 and the annular regions formed between the inner or outer flanges 602 or 604 and one of the annular stiffeners 606 have substantially equal radial heights, respectively.

[0047] In certain examples, the aft bulkhead 138 is formed with one or more radial stiffeners 608 that extend radially from the inner flange 602 to the outer flange 604. The radial stiffeners 608 can be formed on the same side of the web surface 607 as the annular stiffeners 606, as shown. Each radial stiffener 608 can be integrally formed on the web surface 607. Alternatively, the radial stiffeners 608 and / or the annular stiffeners 606 can be formed on the opposite surface of the web 607.

[0048] Figure 7 is another perspective view of the aft bulkhead 138 according to examples of the present disclosure. The depicted embodiment shows the opposite surface of the web 607 from the above-described Figure 6 In certain examples, the aft bulkhead 138 can be oriented such that the smooth web surface 302 faces the hilite 110 of the lip skin assembly 104. The aft bulkhead 138 can have a generally flat body as shown, or alternatively, a substantially concave or conical flat body. Like the forward bulkhead 134, the aft bulkhead 138 can be provided with accessory openings 702 to allow accessories to pass, such as, for example, hot air passages.

[0049] During operation, the aft bulkhead 138 is configured to receive impact loads and suffer some localized damage, and still be able to maintain residual strength using both circumferential and radial load paths from the annular and radial stiffeners, respectively. In other words, the grid pattern of stiffeners provides multiple redundant load paths around a locally damaged area. For example, in the case of a fan blade out event, the aft bulkhead 138 is configured to receive loads from the fan case 131 into the aft bulkhead 138 through the inner barrel 124 and the inner flange 602. The aft bulkhead 138 will result in plastic strain and can locally rupture, but the annular stiffeners 606 and the radial stiffeners 608 maintain the structural stiffness and residual strength of the aft bulkhead 138 after the impact event.

[0050] Figure 8is a partial elevational view showing a rear portion of a rear bulkhead 138 according to an example of the present disclosure. As described above, the rear bulkhead 138 is formed with one or more annular stiffeners 606 joined to the web surface 607 and one or more radial stiffeners 608 intersecting the annular stiffeners 606. The intersection of the annular stiffeners 606 and the radial stiffeners 608 define the boundaries of cells 802 or bays. In certain examples, the cells 802 are formed to have a generally annular sector shape. As known to those skilled in the art, an annular sector or ring sector is a portion of a ring formed by two lines extending radially from the center of the ring. In this example, the cells 802 are defined by a pair of adjacent radially extending stiffeners 608 and an adjacent annular stiffener 606 or annular stiffener 606 and an adjacent flange (e.g., inner flange 602 or outer flange 604).

[0051] As shown, the cells 802 are configured to undergo a compressive buckling and return to their pre-buckled shape (elastic buckling) under a predetermined load. The loads that can cause the elastic compressive buckling event include all flight loads except for the flight load level encountered every other flight when the anti-ice system is turned off (i.e., fatigue loads).

[0052] In certain examples, the inner flange 602 and the outer flange 603 of the rear bulkhead 138 (or the front bulkhead 134) can be formed separately from the web surface 607 and joined to the inner flange 602 or the outer flange 604 via fasteners 804.

[0053] The stiffeners also provide stiffness to resist ovalization of the nacelle inlet to help the fan case 131 maintain the tip clearance 133 of the fan blades 129. The stiffeners also provide stiffness to increase the natural frequency of the inlet, which can yield some benefits in high vibration environments.

[0054] Figure 9 is a flowchart illustrating one example of a method 900 for forming a front or rear bulkhead according to examples of the present disclosure. The method 900 begins and, at block 902, an annular web surface is formed having an inner flange for joining an inner barrel surface of a nacelle inlet and an outer flange for joining an outer barrel surface of the nacelle inlet. At block 904, at least one radial stiffener is formed (e.g., co-formed with or joined to) on a side of the web surface to provide radial and fore-aft stiffness to resist overall displacement in the nacelle inlet. At block 906, at least one annular stiffener is formed (e.g., co-formed with or joined to) on at least one side of the web surface. The radial stiffeners can be formed to intersect the annular stiffeners to form a plurality of cells that are able to buckle under compressive loads in all cases except for the flight load level encountered every other flight when the anti-ice system is turned off (i.e., fatigue loads).

[0055] At block 908, additional thickness and height are formed in both the annular and radial stiffeners to support load redistribution of the cell after the cell buckles. At block 910, additional thickness and height are formed in both the annular and radial stiffeners to ensure that they provide redundant load paths after the bulkhead causes discrete source damage.

[0056] Figure 10 is a cross-sectional view illustrating another embodiment of a front bulkhead 134 according to an example of the present disclosure. The depicted embodiment (not to scale) shows the upper half of the cross-sectional view (as Figure 1 As described above, the front bulkhead 134 is formed with an inner flange 202, an outer flange 204, and a web 208 joining the inner flange 202 to the outer flange 204. Formed on the surface of the web 208 is one or more annular stiffeners 206. Radial stiffeners 210 are not shown here. In certain examples, the web 208 has a thickness 1002 in a range between about 0.030 and 0.065 inches. In other embodiments, the web 208 has a thickness 1002 in a range between about 0.0450 and 0.0550 inches. In certain embodiments, the thickness 1002 of the web 208 is uniform across all cells 402. In other embodiments, the thickness 1002 varies and can increase from the outer flange 204 to the inner flange 202. In other words, the thickness 1002 of the web 208 near the outer flange 204 is less than the thickness 1002 of the web 208 near the inner flange 202.

[0057] In certain embodiments, a transition zone 1004 can be provided near features extending outward from the web 208 (i.e., the inner flange 202, the outer flange 204, the annular stiffeners 206, the radial stiffeners 210). The transition zone 1004 provides an increased thickness in the area adjacent to the feature. This beneficially increased thickness of the transition zone helps to avoid acoustic fatigue issues while maintaining a reduced overall weight of the front bulkhead 134. The transition zone thickness 1006 can be in a range between about 0.100 inches and 0.148 inches. In another embodiment, the transition zone thickness 1006 can be in a range between about 0.110 inches and 0.138 inches.

[0058] In certain embodiments, the front bulkhead 134 has an outer flange thickness 1008 in a range between about 0.090 inches and 0.120 inches. In another embodiment, the outer flange thickness 1008 is in a range between about 0.100 inches and 0.110 inches, and can be about 0.102 inches. The annular stiffener thickness 1010 can be in a range between about 0.130 to 0.160 inches, and in other embodiments, can be in a range between about 0.149 to 0.150 inches. In another embodiment, the annular stiffener thickness 1010 can be in a range between about 0.148 and 0.150 inches. The inner flange 202 can be provided with a thickness 1012 that is greater near the web 208 than a thickness 1014 of the end of the inner flange 202. In some embodiments, the thickness 1012 is about 0.408 inches, and the thickness 1014 is about 0.160 inches.

[0059] As described above with reference to Figure 5 The cell height 506, or radial distance between adjacent annular stiffeners 206, can be substantially uniform across all cells 402 of the front and / or rear bulkheads. Alternatively, the spacing between annular stiffeners 206 can vary. In some embodiments, the cell height 506 is in a range between about 4.50 and 5.50 inches. In other embodiments, the cell height 506 is in a range between about 4.80 and 5.20 inches. In other embodiments, the cell height 506 can be in a range between about 4.83 and 5.13 inches. The width of the cell (i.e., the arc distance between radial stiffeners) can be in a range between about 8.20 to 9.90 inches, and in other embodiments, can be in a range between about 8.35 to 9.82 inches. The thickness of the radial stiffeners (not shown here) can be in a range between about 0.140 inches and 0.160 inches, and in another embodiment, can have a thickness of about 0.150 inches.

[0060] The web height 1016 is defined as the radial distance between the inner flange 202 and the outer flange 204. The web height 1016 can also be defined as the sum of the cell height 506 and the annular stiffener thickness 1010. In certain embodiments, the web height 1016 provided by the front bulkhead 134 is in the range of about 13.0 to 17.0 inches. In other embodiments, the web height 1016 is in the range of between about 14.0 and 16.0 inches. In other embodiments, the web height 1016 is in the range of between about 15.2 and 15.5 inches, and can be about 15.4 inches. The ratio of the web height 1016 to the web thickness 1002 of the front bulkhead 134 can be in the range of between about 255 and 380. The web thickness 1002 of the front bulkhead 134 can be as low as 0.045 inches, and the web height 1016 can be as high as 17.0 inches.

[0061] Figure 11 is a cross-sectional view showing another embodiment of the rear bulkhead 138 according to examples of the present disclosure. The depicted embodiment (not to scale) shows the upper half of the cross-sectional view (as shown by the dashed line Figure 1 As described above, the rear bulkhead 138 is formed by the inner flange 602, the outer flange 604, and the web 607 joining the inner flange 202 to the outer flange 204. One or more annular stiffeners 606 are formed on the surface of the web 607. The radial stiffeners 608 are not shown here. In certain examples, the web 607 has a thickness 1102 in the range of about 0.030 to 0.065 inches, or in the range of about 0.045 to 0.050. In other embodiments, the thickness 1102 of the web 208 is in the range of between about 0.050 inches and 0.130 inches. In other embodiments, the web thickness 1102 is in the range of between about 0.070 inches and 0.110 inches. In certain embodiments, the thickness 1102 of the web 607 is uniform across all of the cells 402. In other embodiments, the thickness 1102 varies, and can increase from the outer flange 604 to the inner flange 602. In other words, the thickness 1102 of the web 607 near the outer flange 604 is less than the thickness 1102 of the web 607 near the inner flange 602.

[0062] In some embodiments, the rear bulkhead 138 has an outer flange thickness 1104 ranging from about 0.090 inches to 0.120 inches. In another embodiment, the outer flange thickness 1104 ranges from about 0.095 inches to 0.105 inches, and may be about 0.010 inches. The annular reinforcement thickness 1106 may range from about 0.130 to 0.160 inches, and in other embodiments, may range from about 0.148 to 0.151 inches. In another embodiment, the annular reinforcement thickness 1106 may range from about 0.148 to 0.151 inches.

[0063] As referenced above Figure 5 The unit height 506 is also described herein. The unit height 506, or the radial distance between adjacent annular reinforcements 606 or inner / outer flanges, may be substantially uniform across all units 402 of the front and / or rear partition. Alternatively, the spacing between the annular reinforcements 206 may vary. In some embodiments, the unit height 506 is in the range of approximately 4.50 to 6.50 inches. In other embodiments, the unit height 506 is in the range of approximately 5.50 to 6.20 inches. In other embodiments, the unit height 506 may be in the range of approximately 5.50 to 6.13 inches. The width of the unit (i.e., the arc distance between the radial reinforcements) may be in the range of approximately 8.20 to 10.2 inches, and in other embodiments, may be in the range of approximately 8.30 to 10.1 inches. The thickness of the radial reinforcements (not shown herein) may be in the range of approximately 0.140 inches to 0.160 inches, and in another embodiment, may have a thickness of approximately 0.150 inches.

[0064] The web height 1108 is defined as the radial distance between the inner flange 602 and the outer flange 604. The web height 1108 can also be defined as the sum of the unit height 506 and the thickness 1106 of the annular reinforcement. In some embodiments, the web height 1108 provided by the rear bulkhead 138 is in the range of about 14.0 to 19.0 inches. In other embodiments, the web height 1108 is in the range of about 14 to 18 inches. In other embodiments, the web height 1108 is in the range of about 17.6 to 17.9 inches, and may be about 17.8 inches. The rear bulkhead 138 may have a ratio of web height 1108 to web thickness 1102 in the range of about 210 to 410. The rear bulkhead web thickness 1102 may be as low as 0.045, and the web height 1108 as high as 20.0 inches.

[0065] In the above description, certain terms can be used such as "upper," "lower," "upper portion," "lower portion," "horizontal," "vertical," "left," "right," "above," "below," and the like. These terms are used herein for the purpose of providing some clarity in describing the relative relationships of the components. However, these terms are not intended to imply absolute relationships, positions, and / or orientations. For example, for an object, an "upper" surface can become a "lower" surface simply by turning the object over. Nonetheless, it is still the same object. Moreover, the terms "comprise," "include," "have," and variations thereof, mean "including but not limited to," unless expressly specified otherwise. A list of items enumerating items does not imply that any or all of the items are mutually exclusive and / or are included at the exclusion of others. The terms "a," "an," and "the" also refer to "one or more" unless explicitly stated otherwise. Additionally, the term "plurality" can be defined as "at least two" as defined herein. Furthermore, unless otherwise stated, a plurality of a particular feature does not necessarily mean an entire collection or category of that particular feature.

[0066] Additionally, in the present description, an example of one element "engaging" another element can include both direct and indirect engagement. Direct engagement can be defined as one element engaging another element and making some sort of contact therewith. Indirect engagement can be defined as engagement between two elements that are not in direct contact with each other, but have one or more additional elements between the elements that are engaged. Moreover, as used herein, securing one element to another element can include both direct and indirect securing. Additionally, as used herein, "adjacent" does not necessarily mean in contact. For example, one element can be adjacent to another element without being in contact with that element.

[0067] As used herein, the phrase "at least one of," when used with a list of items, means that a different combination of one or more of the listed items can be utilized and can only require one of the items in the list to be utilized. The item can be a specific object, thing, or category. In other words, "at least one of" means that any combination of items from the list can be utilized or the number of items can be utilized, but can not require all of the items in the list. For example, "at least one of item A, item B, and item C" can mean item A; item A and item B; item B; item A, item B, and item C; or item B and item C. In some instances, "at least one of item A, item B, and item C" can mean, for example and without limitation, two of item A, one of item B, and ten of item C; four of item B and seven of item C; or other suitable combinations.

[0068] The terms "first", "second", and the like, as used herein, merely refer to labels for identifying elements, and do not otherwise impose numerical requirements on the items to which the terms refer. For example, a "second" item does not require that there be a "first" item present.

[0069] As used herein, a system, device, structure, article, element, component, or hardware that is "configured to" perform a particular function is capable of performing the particular function without any alteration, rather than simply having the potential to perform the particular function after a modification, for example, a modification by a user. In other words, a system, device, structure, article, element, component, or hardware that is "configured to" perform a particular function is specifically selected, created, implemented, utilized, programmed, and / or designed in order to perform the particular function. As used herein, "configured to" denotes existing characteristics of a system, device, structure, article, element, component, or hardware that make the system, device, structure, article, element, component, or hardware capable of performing the specified function without any alteration. A system, device, structure, article, element, component, or hardware described as being "configured to" perform a particular function can additionally or alternatively be described as being "adapted to," "made to," "formed to," "programmed to," "operable to," "capable of," and / or the like.

[0070] The illustrative flow diagrams included herein generally are set forth as logical flow diagrams. As such, the depicted order and labeled steps are indicative of one example of the presented method. Other steps and methods can be conceived that are equivalent in function, logic, or effect to one or more steps or portions thereof of the illustrated method. Additionally, the format and symbols employed are provided to explain the logical steps of the method and are understood not to limit the scope of the method. Other steps and methods can be conceived that are equivalent in function, logic, or effect to one or more steps or portions thereof of the illustrated method. Additionally, the format and symbols employed are provided to explain the logical steps of the method and are understood not to limit the scope of the method. Although various arrow types and line styles can be employed in the flow diagram, they are understood not to limit the scope of the corresponding method. Indeed, some arrows or other connectors can be used to indicate only the logical flow of a method. For instance, an arrow can indicate a waiting or monitoring period of unspecified duration between enumerated steps of the depicted method. Additionally, the order in which a particular method occurs can or can not strictly adhere to the order in which the corresponding steps are shown.

[0071] Further, the present disclosure includes implementations in accordance with the following items:

[0072] Item 1. An engine nacelle inlet, comprising:

[0073] an outer barrel;

[0074] an inner barrel;

[0075] a front bulkhead having an outer flange that engages a surface of the outer tub; an inner flange that engages a surface of the inner tub; a web connecting the outer flange to the inner flange; and at least one annular stiffener extending from the web and between the outer flange and the inner flange; and

[0076] a rear bulkhead having an outer flange that engages a surface of the outer tub; an inner flange that engages a surface of the inner tub; a web connecting the outer flange to the inner flange; and at least one annular stiffener extending from the web and between the outer flange and the inner flange.

[0077] Item 2. The engine nacelle inlet of item 1, wherein a ratio of a web height to a web thickness of the front bulkhead is in a range of between about 255 to 380.

[0078] Item 3. The engine nacelle inlet of item 2, wherein the web thickness is greater than or equal to 0.0450 inches and the web height is less than or equal to 17.0 inches.

[0079] Item 4. The engine nacelle inlet of item 1, wherein a ratio of a web height to a web thickness of the rear bulkhead is in a range of between about 210 to 410.

[0080] Item 5. The engine nacelle inlet of item 4, wherein the web thickness is greater than or equal to 0.0450 inches and the web height is less than or equal to 20.0 inches.

[0081] Item 6. The engine nacelle inlet of item 1, wherein:

[0082] the front bulkhead further comprises a plurality of radial stiffeners that are integrally formed with the web; and

[0083] wherein each of the plurality of radial stiffeners extends from the outer flange to the inner flange.

[0084] Item 7. The engine nacelle inlet of item 6, wherein each of the plurality of radial stiffeners intersects the at least one annular stiffener.

[0085] Item 8. The engine nacelle inlet of item 7, wherein the at least one annular stiffener is a first annular stiffener having a first diameter, and further comprising a second annular stiffener having a second diameter.

[0086] Item 9. The engine nacelle inlet of item 8, wherein each of a pair of adjacent radial stiffeners intersects the first annular stiffener and the second annular stiffener to form a cell capable of elastically compressive buckling under all flight loads without exceeding a fatigue load.

[0087] Item 10. The engine nacelle inlet of item 1, wherein:

[0088] the aft bulkhead further comprises a plurality of radial stiffeners integrally formed with the web; and

[0089] wherein each of the plurality of radial stiffeners extends from the outer flange to the inner flange.

[0090] Item 11. The engine nacelle inlet of item 10, wherein each of the plurality of radial stiffeners intersects at least one annular stiffener.

[0091] Item 12. The engine nacelle inlet of item 11, wherein the at least one annular stiffener is a first annular stiffener having a first diameter, and further comprising a second annular stiffener having a second diameter.

[0092] Item 13. The engine nacelle inlet of item 12, wherein each of a pair of adjacent radial stiffeners intersects the first annular stiffener and the second annular stiffener to form a cell capable of elastically compressive buckling under all flight loads without exceeding fatigue loads.

[0093] Item 14. A bulkhead for an aircraft engine nacelle inlet, the bulkhead comprising:

[0094] an annular body having an outer flange and an inner flange; and a web having a first side and an opposite second side, the web extending from the outer flange to the inner flange;

[0095] at least one annular stiffener disposed on the first side; and

[0096] a plurality of radial stiffeners disposed on the first side, wherein each of the plurality of radial stiffeners extends from the outer flange to the inner flange.

[0097] Item 15. The bulkhead of item 14, wherein the at least one annular stiffener is integrally formed with the web, and each of the plurality of radial stiffeners is integrally formed with the web.

[0098] Item 16. The bulkhead of item 14, wherein the at least one annular stiffener is a first annular stiffener having a first diameter, and further comprising a second annular stiffener having a second diameter.

[0099] Item 17. The bulkhead of item 16, wherein each of a pair of adjacent radial stiffeners intersects the first annular stiffener and the second annular stiffener to form a cell capable of elastically compressive buckling under all flight loads without exceeding fatigue loads.

[0100] Item 18. The bulkhead of item 14, further comprising a ratio of web height to web thickness between about 210 to 410.

[0101] Item 19. The bulkhead of item 18, wherein the web height is less than or equal to 20.0 inches and the web thickness is greater than or equal to 0.0450 inches.

[0102] Item 20. A method of forming a bulkhead for a nacelle of an aircraft engine, the method comprising:

[0103] forming an annular web surface having an inner flange and an outer flange;

[0104] forming at least one annular stiffener on one side of the annular web surface; and

[0105] forming a plurality of radial stiffeners on the side of the annular web surface.

[0106] The subject matter can be embodied in other specific forms without departing from the spirit or essential characteristics thereof. The described examples are to be considered in all respects only as illustrative and not restrictive. All changes coming within the meaning and equivalency range of the claims are intended to be embraced therein.

Claims

1. An engine nacelle inlet (100) comprising: an outer barrel (120); an inner barrel (124); a forward bulkhead (134) having an outer flange (204) engaged with a surface of the outer barrel (120); an inner flange (202) engaged with a surface of the inner barrel (124); a single web (208) extending in a plane connecting the outer flange (204) to the inner flange (202); and at least one annular stiffener (206) extending from the web (208) and interposed between the inner flange (202) and the outer flange (204); and a rear bulkhead (138) having an outer flange (604) engaged to a surface of the outer barrel (120); an inner flange (602) engaged to a surface of the inner barrel (124); a single web (607) extending in a plane connecting the outer flange (604) of the rear bulkhead to the inner flange (602) of the rear bulkhead; and at least one annular stiffener (606) extending from the web (607) of the rear bulkhead and interposed between the outer flange (604) of the rear bulkhead and the inner flange (602) of the rear bulkhead, wherein the forward bulkhead (134) further comprises a plurality of radial stiffeners (210) integral with the web (208) of the forward bulkhead; and wherein each of the plurality of radial stiffeners (210) of the forward bulkhead extends in a straight line from the outer flange (204) of the forward bulkhead to the inner flange (202) of the forward bulkhead, wherein the rear bulkhead (138) further comprises a plurality of radial stiffeners (608) integral with the web (607) of the rear bulkhead; and wherein each of the plurality of radial stiffeners (608) of the rear bulkhead extends in a straight line from the outer flange (604) of the rear bulkhead to the inner flange (602) of the rear bulkhead wherein the rear bulkhead is provided with openings that allow passage of hot air.

2. The engine pod inlet (100) of claim 1, wherein, A ratio of a web height (1016) to a web thickness (1002) of the forward bulkhead (134) is in a range between 255 and 380.

3. The engine pod inlet (100) of claim 2, wherein, The web thickness (1002) is greater than or equal to 0.0450 inches and the web height (1016) is less than or equal to 17.0 inches.

4. The engine pod inlet of claim 1, wherein, A ratio of a web height to a web thickness of the rear bulkhead is in a range between 210 and 410.

5. The engine pod inlet (100) of claim 1, wherein, Each of the plurality of radial stiffeners (210) of the forward bulkhead intersects the at least one annular stiffener (206) of the forward bulkhead.

6. The engine pod inlet (100) of claim 5, wherein, The at least one annular stiffener (206) of the forward bulkhead is a first annular stiffener having a first diameter and further comprises a second annular stiffener having a second diameter.

7. The engine pod inlet (100) of claim 6, wherein, Each of a pair of adjacent radial stiffeners (210) intersects the first annular stiffener (206) and the second annular stiffener (206) of the forward bulkhead to form a cell capable of elastically compressive buckling under all flight loads without exceeding fatigue loads.

8. A method of forming a bulkhead for a nacelle of an aircraft engine, the method comprising: forming a single annular web surface having an inner flange and an outer flange; forming at least one annular stiffener on one side of the annular web surface; and forming a plurality of radial stiffeners on the side of the annular web surface, wherein each of the plurality of radial stiffeners extends in a straight line from the outer flange to the inner flange wherein the bulkhead is provided with openings to allow passage of hot air.

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