NACELLE AIR INTAKE WITH AN ACOUSTIC PANEL

Abstract

An air intake of a turbojet engine nacelle includes an annular structure including an outer fairing defining an aerodynamic outer surface and an inner fairing defining an aerodynamic inner surface. The outer and inner fairings are connected upstream by an air intake lip forming a leading edge. The inner fairing includes an outer skin fixed to the air intake lip by an upstream fixation flange, and the outer skin is configured to be fixed to an outer fan casing by a downstream fixation flange. The air intake includes at least one independent acoustic panel attached to the outer skin and which includes a perforated acoustic skin and a cellular core.

Claims

1. An air intake of a turbojet engine nacelle comprising an annular structure comprising an outer fairing defining an outer aerodynamic surface and an inner fairing defining an inner aerodynamic surface, said outer and inner fairings being connected upstream by an air intake lip forming a leading edge, said inner fairing comprising an outer skin fastened to the air intake lip by an upstream fastening flange, said outer skin configured to be fastened to a fan outer casing by a downstream fastening flange, the air intake comprising at least two independent acoustic panels attached to the outer skin and comprising a perforated acoustic skin and a cellular core, said at least two acoustic panels being adjacent and connected together by overlapping.

2. The air intake according to claim 1, wherein the upstream fastening flange is integral with the outer skin.

3. The air intake according to claim 1, wherein the upstream fastening flange forms an angle in the range of 90° with the outer skin.

4. The air intake according to claim 1, wherein the outer skin is made of a composite material.

5. The air intake according to claim 1, wherein the at least two independent acoustic panels are removably attached to the outer skin.

6. The air intake according to claim 1, wherein the at least two independent acoustic panels are made of a metallic material.

7. The air intake according to claim 6, wherein the cellular core is fastened to the perforated acoustic skin by brazing.

8. The air intake according to claim 1, wherein at least one of the at least two independent acoustic panels comprises an overlapping strip designed so as to be superimposed with the adjacent acoustic panel.

9. The air intake according to claim 1, wherein at least one movable hatch is arranged at a level of the annular structure.

10. A propulsion unit comprising the air intake according to claim 1 and a fan comprising a plurality of fan blades, wherein the outer skin of the air intake on which at least one acoustic panel is attached has a shape diverging from the air intake lip up to the fan blades and the propulsion unit has a radial clearance between the outer skin and the fan blades formed by a setback of at least one acoustic panel.

11. A method for depositing a fan blade of a propulsion unit according to claim 10, the method comprising: depositing at least one independent acoustic panel attached to the outer skin so as to form a radial clearance; and translating a fan blade to be deposited according to an axial displacement in a direction of the air intake lip allowed by the radial clearance.

12. The method according to claim 11 further comprising rotating the fan so as to position a fan blade to be deposited opposite the deposited acoustic panel.

13. The method according to claim 11, wherein the acoustic panel is attached to the outer skin by fastening flanges, and wherein the method further comprises removing a movable hatch from an annular structure to access the fastening flanges of the acoustic panel.

Description

DRAWINGS

[0050] In order that the disclosure may be well understood, there will now be described various forms thereof, given by way of example, reference being made to the accompanying drawings, in which:

[0051] FIG. 1 is a schematic representation in longitudinal section of a nacelle air intake according to the present disclosure;

[0052] FIG. 2 is a further schematic representation in longitudinal section of the nacelle air intake according to the present disclosure;

[0053] FIG. 3 is a schematic representation in cross-section of a partial view of the air intake comprising several acoustic panels according to the present disclosure;

[0054] FIG. 4 is an enlarged view of the acoustic panels according to the present disclosure;

[0055] FIG. 5 is another enlarged view of the acoustic panels according to the present disclosure;

[0056] FIG. 6 is a representation of a nacelle air intake according to the prior art;

[0057] FIG. 7 is a schematic representation of a deposition of a fan blade according to the present disclosure;

[0058] FIG. 8 is a schematic representation of a deposition of a fan blade according to the present disclosure;

[0059] FIG. 9 is a schematic representation of an air intake according to a feature of the present disclosure;

[0060] FIG. 10 is a schematic representation of an air intake according to another feature of the present disclosure; and

[0061] FIG. 11 is a schematic representation in longitudinal section of a nacelle air intake according to a feature of the present disclosure.

[0062] The drawings described herein are for illustration purposes only and are not intended to limit the scope of the present disclosure in any way.

DETAILED DESCRIPTION

[0063] The following description is merely exemplary in nature and is not intended to limit the present disclosure, application, or uses. It should be understood that throughout the drawings, corresponding reference numerals indicate like or corresponding parts and features.

[0064] The expressions “upstream” and “front” will be used interchangeably to refer to the upstream of the air intake, and the expressions “downstream” and “rear” will be used interchangeably to refer to the downstream of the air intake.

[0065] The expressions “upstream” and “downstream” refer to the direction of the air flow coming in and out of a nacelle.

[0066] FIG. 1 illustrates an air intake 1 of a turbomachine nacelle. The air intake comprises an air intake lip 108 and an annular structure 110. The annular structure 110 comprises an outer fairing 100 defining an outer aerodynamic surface and an inner fairing 102 defining an inner aerodynamic surface. The outer fairing 100 and the inner fairing 102 are connected at their upstream ends 104, 106, by the air intake lip 108 forming a leading edge. The air intake lip 108 provides the junction between the two fairings 100, 102 and could be integrated to the outer fairing 100 of the air intake 1. The air intake lip 108 is delimited by a partition 112, called a “front partition,” which forms an annular shaped volume with a “D”-like shaped section. In one aspect, the partition is made of titanium and is fastened to the air intake lip by a fastening flange 113 having an L-like shape. In another aspect, the fastening flange 113 is also made of titanium.

[0067] The inner fairing 102 of the air intake 1 comprises an outer skin 114. The outer skin 114 extends from a fan outer casing 116 up to the air intake lip 108. The fan outer casing 116 surrounds a fan 136 comprising fan blades 126. In the present example, one single fan blade is represented.

[0068] The fan 136 is designed so as to be rotated. The rotation of the fan 136 drives the fan blades 126 which compress air coming into the turbojet engine.

[0069] The outer skin 114 is fastened at its upstream end 106 to the air intake lip 108 by an upstream fastening flange 118 and is fastened at its downstream end 120 to the fan casing 116 by a downstream fastening flange 122. The downstream end 120 of the outer skin 114 may be connected to the inner periphery of a transverse annular partition 124 for reinforcement and load transmission, called a “rear partition,” whose outer periphery is connected to the outer fairing 100 of the air intake 1.

[0070] Thus, the outer skin 114 provides the transmission of loads from the air intake lip 108 up to the fan casing 116. The outer skin 114 is structural.

[0071] The upstream fastening flange 118 may be integral with the outer skin 114. By integral with, it should be understood that the upstream fastening flange 118 and the outer skin 114 are formed in one piece. In one aspect, the fastening flange and the outer skin are made of a composite material such as dry fibers infused in a thermoplastic resin. The upstream fastening flange 118 and the outer skin 114 may be made by shape forming. Shape forming comprises setting the material to be deformed in place on a first tooling and deforming the material by a second tooling having the desired final shape. This method also allows forming an angle comprised between 80° and 100° between the upstream fastening flange 118 and the outer skin; in one form, the upstream fastening flange 118 forms an angle of 90° with the outer skin 114.

[0072] The air intake 1 comprises an independent acoustic panel 2. The acoustic panel 2 comprises a perforated acoustic skin 200. The perforated acoustic skin 200 comprises a plurality of holes (not shown) evenly formed in the acoustic skin 200.

[0073] The acoustic panel 2 also comprises a cellular core 202 including a plurality of acoustic cells which are separated from each other by peripheral partitions 204.

[0074] FIG. 2 illustrates the air intake 1 for a turbomachine nacelle wherein the acoustic panel 2 is attached to the outer skin 114.

[0075] The acoustic panel 2 is attached to the outer skin 114 by fastening flanges 208, 210. By attached acoustic panel, it should be understood a panel manufactured separately from the outer skin 114 of the air intake 1 and which is assembled afterwards on this outer skin 114.

[0076] The acoustic panel 2 could be removably fastened on the outer skin 114 to facilitate replacement thereof in case of deterioration.

[0077] The acoustic panel 2 extends along the outer skin 114 from the air intake lip 108 up to the fan casing 116. Thus, the acoustic panel 2 is disposed upstream of fan blades 126.

[0078] Thus, the structural and acoustic functions are disassociated. The structural function enabling the transmission of loads is provided by the outer skin 114 of the inner fairing which extends from the air intake lip 108 up to the fan casing 116. The acoustic treatment function is provided by the acoustic panel 2 attached to the outer skin 114 by the fastening flanges 208, 210. Because the manufacture of the acoustic panel is independent of the manufacture of the air intake, the making of the acoustic panel is not subjected to the manufacturing constraints of this air intake (in particular to the pressure and temperature constraints).

[0079] Thus, the acoustic panel 2 may be made of a metallic material and/or of a composite material. In one form, both the acoustic skin and the cellular core may be made of a metallic material. In another form, the acoustic skin and the cellular core are made of aluminum, and in other forms, the acoustic skin and the cellular core may be made of an aluminum alloy selected in the 6000 series. The metallic cellular core is fastened to the metallic acoustic skin by brazing. The metallic acoustic skin is pierced with a micro-piercing technique carried out by laser.

[0080] The use of these different materials is made possible because of the separation of the acoustic and structural functions.

[0081] FIG. 3 is a partial view of the air intake in cross-section according to the plane IV-IV of FIG. 2. This figure shows two independent acoustic panels 2, 2′ comprising one perforated skin 200, 200′, respectively, attached to the outer skin 114 and fastened thereon by fastening flanges (not shown).

[0082] Although the example of FIG. 3 shows an air intake comprising two acoustic panels attached to the outer skin, it is considered to attach other acoustic panels to cover the entirety of the circumference of the air intake of the nacelle.

[0083] FIGS. 4 and 5 are enlarged views of the section V of FIG. 3 which illustrate variants of the form of the air intake illustrated in FIG. 3.

[0084] Referring to FIG. 4, the two acoustic panels 2, 2′ are adjacent and connected to one another by juxtaposition, that is to say edge-to-edge.

[0085] According to a second variant illustrated in FIG. 5, the acoustic panels 2, 2′ are adjacent and connected together by overlapping.

[0086] In this variant, an overlapping strip 201′ of the perforated acoustic skin 200′ of the first acoustic panel 2′ is designed so as to be superimposed with the perforated acoustic skin 200 of the adjacent acoustic panel.

[0087] FIG. 6 is an illustration of a propulsion unit 5′ of the prior art on which it is possible to view a deposition of a fan blade 126′. The propulsion unit 5′ comprises a nacelle air intake 1′ and a fan casing 116′ surrounding a fan 136′ including a fan blade 126′. The deposition of the fan blades might be performed for servicing or repairing the fan blades.

[0088] The air intake 1′ comprises an air intake lip 108′ and an annular structure 110′.

[0089] The annular structure 110′ comprises an outer fairing 100′ defining an outer aerodynamic surface and an inner fairing 102′ defining an inner aerodynamic surface. The air intake 1′ of the nacelle has a substantially frustoconical shape.

[0090] The axial translational displacement along the direction of the arrow (a) towards the air intake lip 108′ of the fan blade 126′ causes an interference (represented in section VI) of the blade 126′ with the air intake. This is encountered in particular with short nacelles, which converge in the direction of the air intake lip.

[0091] FIGS. 7 and 8 illustrate the deposition of a fan blade 126 of a propulsion unit 5 according to a form of the present disclosure wherein at least one attached acoustic panel has been removed. In the present example, one single acoustic panel 2 has been removed. The propulsion unit 5 has a nacelle air intake 1 including an air intake lip 108 and an annular structure 110, a fan outer casing 116 surrounding a fan 136 including a fan blade 126. FIG. 8 illustrates more particularly the displacement of the fan blade 126 to be deposited in axial translation along the direction of the arrow (a) towards the air intake lip 108.

[0092] The air intake of the nacelle having a substantially frustoconical shape, the outer skin 114 of the air intake therefore has a shape diverging from the air intake lip 108 up to the fan blade 126.

[0093] The setback of the attached acoustic panel 2 allows forming a radial clearance (r) between the outer skin 114 and the fan blade 126 such that the fan blade 126 does not come into contact with the air intake 1 during its axial translational displacement.

[0094] At least one independent acoustic panel 2 is offset from the outer skin 114 to form a radial clearance (r). The fan comprising the fan blades is rotated, for example manually, so as to position the fan blade to be deposited opposite the panel(s) that has/have been deposited and then the fan blade 126 is displaced in translation according to an axial displacement (a) in the direction of the air intake lip 108 allowed by the radial clearance (r). The fan blade 126 does not interfere with the air intake 1 during its displacement in axial translation.

[0095] FIG. 9 illustrates an air intake 1 comprising an air intake lip 108 and an annular structure 110 including an outer fairing 100. The annular structure 110 includes a hatch 4 movable between a closed position in which the hatch is flush with the outer fairing 100 and an open position in which the hatch opens access to the acoustic panel 2. The hatch is adapted to be completely removed from the outer fairing 100 (FIG. 10). The removal of the movable hatch allows accessing the acoustic panel without having to deposit the outer fairing of the air intake lip.

[0096] The hatch may also be used to provide access to other elements that might be present in the air intake such as elements of a deicing system or probes used for engine monitoring.

[0097] FIG. 11 illustrates the air intake 1 of a turbomachine nacelle wherein the hatch 4 has been removed from the annular structure to allow access to the fastening flanges 208, 210 of the acoustic panel 2. The hatch 4 is removed from the outer fairing 100 of the annular structure 110 to allow access to the fastening flanges 208, 210 of an acoustic panel 2 to be removed. The acoustic panel 2 is deposited. The fan 136 comprising the fan blades is rotated so as to position the fan blade to be deposited opposite the deposited acoustic panel. The fan blade 126 to be deposited is displaced by axial translation along the direction of the arrow (a) in the direction of the air intake lip 108 allowed by the radial clearance (r) (FIG. 8). Because of the deposition of the acoustic panel 2, the fan blade 126 does not come into contact with the air intake during deposition thereof.

[0098] Thus, because of the air intake according to the present disclosure wherein the acoustic panel is attached rather than structural, maintenance and repair operations are simplified. In addition, it is possible to desirably control the making of the perforations in the acoustic skin so as to limit aerodynamic losses.

[0099] Unless otherwise expressly indicated herein, all numerical values indicating mechanical/thermal properties, compositional percentages, dimensions and/or tolerances, or other characteristics are to be understood as modified by the word “about” or “approximately” in describing the scope of the present disclosure. This modification is desired for various reasons including industrial practice, material, manufacturing, and assembly tolerances, and testing capability.

[0100] As used herein, the phrase at least one of A, B, and C should be construed to mean a logical (A OR B OR C), using a non-exclusive logical OR, and should not be construed to mean “at least one of A, at least one of B, and at least one of C.”

[0101] The description of the disclosure is merely exemplary in nature and, thus, variations that do not depart from the substance of the disclosure are intended to be within the scope of the disclosure. Such variations are not to be regarded as a departure from the spirit and scope of the disclosure.