Assembly of a turbine engine fan casing and a nacelle air duct

Abstract

The invention relates to an assembly of a turbine engine fan casing (2), in particular for an aircraft, and a nacelle air duct (3), the turbine engine extending along a longitudinal axis (X) and comprising at least one fan mounted so as to be rotatable about the longitudinal axis (X) so as to accelerate an air flow from upstream to downstream, the fan casing (2) comprising an upstream flange (21) connected to a downstream flange (31) of the air duct (3) by a plurality of mechanical members (4). The assembly comprises at least one stiffening element (5), positioned radially outside the air duct (3), the stiffening element (5) comprising a planar base (51) extending radially, the base (51) being arcuate and connected to the downstream flange (31) of the air duct (3) by at least five mechanical members (4).

Description

Assembly of a turbomachine blower housing and a nacelle air duct

[0001] The present invention relates to the field of aircraft turbomachinery, in particular, the joining of a nacelle air duct to a turbomachine fan casing.

[0002] In a known manner, with reference to the example, an aircraft turbomachine 100 extends along a longitudinal axis X and includes a fan 101, rotatably mounted about said longitudinal axis X, which propels the aircraft from an upstream to a downstream airflow accelerated by the turbomachine 100. Hereafter, the terms "upstream" and "downstream" are defined with respect to the upstream-to-downstream oriented longitudinal axis X. Similarly, the terms "inside" and "outside" are defined with respect to the radial direction with respect to the longitudinal axis X. In a known manner, the turbomachine 100 includes a compressor, a combustion chamber, and a turbine to drive the compressor in rotation. In this example, the turbomachine 100 is a dual-flow turbomachine and has a bypass ratio greater than 16.

[0003] The fan 101 comprises a plurality of blades 111. Each blade 111 extends radially about the longitudinal axis X and has a free apex at its distal end. The turbomachine 100 includes a fan housing 102 extending longitudinally along the longitudinal axis X, in which the fan 101 is housed. The fan housing 102 defines an annular cavity for airflow circulation. The fan housing 102 includes an upstream flange 121 for mounting a nacelle air duct 103, also called an "air inlet," upstream of the fan housing. As is known, the air sleeve 103 comprises a downstream flange 131 connected to the upstream flange 121 of the blower housing 102 by a plurality of mechanical components 104, in particular, bolts. As is known, such an air sleeve 103 serves to guide the airflow upstream and towards the blower housing 102.

[0004] In the schematic representation, the upstream end of the nacelle air duct 103 is schematically represented as having an upstream nacelle air inlet. A nacelle is conventionally configured to receive equipment forming the outer shell of the turbomachine, particularly around the fan casing 102. Thus, the nacelle air duct 103 forms a radially inner part of the nacelle.

[0005] However, cases of blade loss 111 are known, meaning cases where at least one blade 111 detaches from the fan 101 or a portion of a blade breaks upon impact, for example. In such cases, under the effect of centrifugal force, the blade 111 or the portion of blade 111 is thrown against the fan housing 102, generating an impact that causes radial displacement of the flanges of the fan housing 102 and the air duct 103, particularly at the point where they are connected by the mechanical components 104. As a result, the mechanical components 104 are subjected to bending, which can weaken them and reduce their service life.

[0006] In particular, residual play can develop between the fan casing and the air duct. Such residual play presents numerous drawbacks, such as the risk of potential damage to the turbomachine around its fan in the event of severe foreign object ingestion impacting the fan, for example, during the ingestion of very large birds in flight. By limiting the residual play, i.e., the geometric variations in the fan casing, the turbomachine's integrity is improved in the event of large bird ingestion. Furthermore, residual play could potentially allow a fan blade fragment to pass through in the event of an impact. Finally, such residual play could also allow air to flow between the fan casing and the air duct, which could potentially fuel a fire in the assembly formed by the fan casing, the air duct, and the nacelle.

[0007] US20130032669A1, EP2703148B1, FR3121951A1 and US2024255056A1 teach different connecting elements in a turbomachine.

[0008] The invention thus aims to eliminate at least some of these drawbacks. PRESENTATION OF THE INVENTION

[0009] The invention relates to an assembly of a turbomachine fan housing, in particular for aircraft, and a nacelle air duct, the turbomachine extending along a longitudinal axis and comprising at least one fan mounted to rotate about the longitudinal axis so as to accelerate an upstream to downstream airflow, the fan housing comprising an upstream flange connected to a downstream flange of the air duct by a plurality of mechanical components.

[0010] The assembly is remarkable in that it includes at least one stiffening element, positioned radially outside the air sleeve, the stiffening element comprising a flat base extending radially, the base being arched and connected to the downstream flange of the air sleeve by at least five mechanical components.

[0011] Thus, the stiffening element is a reinforcing plate whose length and thickness allow it to absorb the longitudinal, radial, and potentially torsional forces generated at the connection between the fan housing and the air duct. This strengthens the connection between the fan housing and the air duct, notably by adding material in a localized manner and therefore additional stiffness. In the event of blade loss, the absorption of the forces transmitted between the upstream flange of the fan housing and the downstream flange of the air duct by the mechanical components prevents breakage and / or cracking of these components. In particular, this prevents the formation of residual play between the fan housing and the air duct, thus limiting the risk of damage to the turbomachine.

[0012] Preferably, the stiffening element is mounted separately on the air sleeve.

[0013] The stiffening element can therefore be integrated into an existing turbomachine, by being mounted on the air duct of said turbomachine.

[0014] Preferably, the stiffening element is a single piece. This increases robustness. Alternatively, the stiffening element could be made by assembling several parts.

[0015] In one aspect, the stiffening element extends circumferentially along an angular arc. This allows for the circumferential distribution of mechanical stresses in the event of blade loss.

[0016] In one aspect, the assembly comprises a plurality of stiffening elements.

[0017] Preferably, a plurality of stiffening elements are distributed circumferentially outside the air sleeve, each stiffening element being connected to the downstream flange of the air sleeve.

[0018] The multiple stiffening elements distributed along the air duct add additional stiffness at various points, limiting the radial forces transmitted between the upstream flange of the blower housing and the downstream flange of the air duct by the mechanical components. This strengthens the connection between the air duct and the blower housing, reducing the risk of relative radial displacement of the blower housing flanges and the air duct. This also limits the bending of the mechanical components and therefore their potential failure and / or cracking in the event of a blade loss.

[0019] Alternatively, a single stiffening element has a plurality of through openings, said stiffening element being connected to the downstream flange of the air sleeve by a plurality of mechanical parts connecting the upstream flange of the blower housing to the downstream flange of the air sleeve, each mechanical part passing through one of the plurality of through openings respectively.

[0020] In one aspect, the base is connected to the downstream flange of the air sleeve by only five or six mechanical components. This ensures a compromise between robustness and size.

[0021] In one respect, the mechanical components are bolted components.

[0022] According to one aspect, the at least five mechanical components are consecutive.

[0023] In one respect, the stiffening element consists of the base. The structure of the stiffening element is therefore very simple, which reduces its mass and facilitates its manufacture.

[0024] According to one aspect, the base extends circumferentially and parallel to the downstream flange around a cylindrical section of the air sleeve adjacent to the downstream flange.

[0025] The invention also relates to a turbomachine, particularly for aircraft, comprising a fan housing and nacelle air duct assembly as previously described, the turbomachine extending along a longitudinal axis and comprising at least one fan mounted movably in rotation within the fan housing along the longitudinal axis so as to accelerate an upstream to downstream airflow. PRESENTATION OF THE FIGURES

[0026] The invention will be better understood upon reading the following description, given by way of example, and referring to the following figures, given by way of non-limiting examples, in which identical references are given to similar objects.

[0027] This is a schematic representation of a longitudinal cross-sectional view of an aircraft turbomachine according to the prior art, including a fan casing.

[0028] This is a close schematic representation in a longitudinal half-section of the blower housing, connected to an air sleeve according to the prior art.

[0029] Laest is a schematic representation of a longitudinal half-section view of a turbomachine according to an embodiment of the invention comprising a blower housing connected to an air sleeve.

[0030] This is a close schematic representation of the connection between the blower housing and the air sleeve of the nacelle.

[0031] It should be noted that the figures explain the invention in detail for implementing the invention, said figures being of course able to serve to better define the invention where appropriate. DETAILED DESCRIPTION OF THE INVENTION

[0032] With reference to the aforementioned invention, the invention will be presented for an aircraft turbomachine T, in particular, a turbojet engine. The turbomachine T extends along a longitudinal axis X and comprises a fan 1 mounted for rotation about the longitudinal axis X, which propels the aircraft by means of an airflow entering the turbomachine T and circulating from upstream to downstream. Hereafter, the terms "upstream" and "downstream" are defined with respect to the longitudinal axis X oriented from upstream to downstream. Similarly, the terms "inside" and "outside" are defined with respect to the radial direction with respect to the longitudinal axis X. In a known manner, the turbomachine T comprises a compressor, a combustion chamber, and a turbine to drive the compressor. Preferably, the turbomachine T is a dual-flow turbomachine with a bypass ratio greater than 16.

[0033] With reference to Figures 3 and 4, the turbomachine T comprises a fan housing 2 and a nacelle air duct 3 mounted upstream of the fan housing 2. The fan housing 2 includes at its upstream end an upstream mounting member, corresponding in particular to an upstream flange 21. Similarly, the air duct 3 includes at its downstream end a downstream mounting member, corresponding in particular to a downstream flange 31, configured to cooperate with the upstream flange 21 of the fan housing 2. Thus, the air duct 3 can be mounted on the fan housing 2 by means of a plurality of mechanical members 4. Preferably, the flanges 21, 31 extend radially to achieve an axial connection through the mechanical members 4.

[0034] As is known, each mechanical component 4 consists of bolted screws that connect the air duct 3 to the blower housing 2, and more specifically, that secure the downstream flange 31 of the air duct 3 against the upstream flange 21 of the blower housing 2. In particular, each mechanical component 4 comprises at least one threaded screw 40 passing through the upstream flange 21 of the blower housing 2 and the downstream flange of the air duct. The threaded screw 40 has a head that bears against the downstream flange 31 and a foot onto which a nut 41 is screwed, which bears against the upstream flange 21.

[0035] The entire blower housing 2 and nacelle air duct 3 assembly is notable in that it includes at least one stiffening element 5. This stiffening element 5 is positioned radially outside the air duct 3. In particular, the stiffening element 5 comprises a radially extending flat base 51. The base 51 is attached to the upstream end of the downstream flange 31 of the air duct 3, as illustrated in Figure 1. The base 51 is curved and connected to the downstream flange 31 of the air duct 3 by at least five mechanical components 4.

[0036] The stiffening element 5 is a reinforcement plate whose length and thickness allow it to absorb the longitudinal, radial, and torsional forces generated at the connection between the blower housing 2 and the air duct 3. This strengthens the connection between the blower housing 2 and the air duct 3, notably by adding material in a localized manner and thus increasing stiffness. The forces exerted by at least five mechanical components 4 are optimally absorbed. The reinforcement plate has a simple design, which facilitates its manufacture and reduces its overall weight.

[0037] As illustrated in Figure 1, the stiffening element 5 extends circumferentially along an angular arc. The angular opening is variable to achieve high robustness and reduced weight. Preferably, the angular opening covers at least five consecutive mechanical components. The base 51 extends circumferentially and parallel to the downstream flange 31 around a cylindrical section of the air sleeve 3 adjacent to the downstream flange 31.

[0038] The stiffening element 5 can be attached to the air duct 3, allowing it to be integrated into an existing air duct 3. In this example, the stiffening element 5 is a single piece, as shown in the figures, simplifying its manufacture and, more importantly, providing greater rigidity. Alternatively, the stiffening element 5 could be made by assembling several parts.

[0039] According to a first embodiment and with reference to the, the stiffening element 5 has at least five through openings formed in the base 51. The stiffening element 5 is connected to the downstream flange 31 of the air sleeve 3 by at least five mechanical parts 4 connecting the upstream flange 21 of the blower housing 2 to the downstream flange 31 of the air sleeve 3, passing respectively through the two through openings.

[0040] In the preferred embodiment shown in Figure 1, the stiffening element 5 has a plurality of through-holes, here five. The stiffening element 5 is connected to the downstream flange 31 of the air duct 3 by a plurality of mechanical components 4, at least five consecutive mechanical components 4. In Figure 1, the stiffening element 5 is connected to the downstream flange 31 of the air duct 3 by five mechanical components 4, connecting the upstream flange 21 of the blower housing 2 to the downstream flange 31 of the air duct 3, each mechanical component 4 passing through one of the plurality of through-holes. In this embodiment, the through-holes allow the passage of the threaded screws 40 of the mechanical components 4. Thus, the head of each threaded screw 40, instead of being in contact with the downstream flange 31 of the air duct 3, is in contact with the stiffening element 5.In other words, the stiffening element 5 is interposed between the downstream flange 31 of the air sleeve 3 and the head of the threaded screw 40 of the mechanical component 4. The stiffening element 5, having at least five through openings, allows for better load distribution between the various mechanical components 4. According to one aspect, the base 5 is connected to the downstream flange 31 of the air sleeve 3 by only five or six mechanical components 4.

[0041] Advantageously, when the mechanical component 4 is associated with one or more interface components (washer, spacer, etc.), the stiffening element 5 can be associated with the mechanical component 4 in place of one or more interface components. In other words, it is not necessary to replace the mechanical components 4 according to the prior art to allow the mounting of a stiffening element 5, which is advantageous.

[0042] This embodiment allows for a localized increase in the rigidity of the connection between the downstream flange 31 of the air duct 3 and the upstream flange 21 of the fan housing 2, specifically at the point where torsion is likely to occur due to radial loading. In other words, the drawbacks of the prior art are addressed at their source. The stiffening elements 5 limit the bending of the mechanical component 4 at which the stiffening element 5 is located and prevent, or at least limit, the risk of breakage and / or cracking. Furthermore, this embodiment allows the stiffening element 5 to be added to an existing turbomachine without requiring modification of the air duct 3 or the fan housing 2, or the addition of any extra parts other than the stiffening element 5, thus avoiding complicating the assembly and increasing its cost.Thus, this solution is applicable to all turbomachines on the market and can be implemented practically and quickly during a maintenance step.

[0043] The assembly may include a plurality of stiffening elements 5 distributed circumferentially on the outside of the air sleeve 3, each stiffening element 5 being connected to the downstream flange 31 of the air sleeve 3. The plurality of stiffening elements 5 distributed on the air sleeve 3 allows for the addition, at various points along the air sleeve 3, of extra stiffness, limiting the radial forces transmitted between the upstream flange 21 of the blower housing 2 and the downstream flange 31 of the air sleeve 3 by the mechanical components 4. Thus, the connection between the air sleeve 3 and the blower housing 2 is more robust overall, limiting the risk of relative radial displacement of the flanges of the blower housing 20 and the air sleeve 3, particularly at their connection by the mechanical components 4, and thereby also limiting the bending of the mechanical components 4 and therefore their breakage and / or cracking in the event of blade loss 11.

[0044] The assembly may also include a single stiffening element 5. This stiffening element 5 has a plurality of through-holes and is connected to the downstream flange 31 of the air sleeve 3 by a plurality of mechanical components 4. The number of through-holes corresponds to the number of mechanical components 4 with which the through-holes interact, each mechanical component 4 passing through one of the plurality of through-holes. Such a stiffening element 5 is interposed between at least five consecutive mechanical components 4, and therefore has at least five through-holes.

Claims

An assembly of a fan casing (2) of a turbomachine (T), particularly for aircraft, and a nacelle air duct (3), the turbomachine (T) extending along a longitudinal axis (X) and comprising at least one fan (1) mounted to rotate about the longitudinal axis (X) so as to accelerate an upstream to downstream airflow, the fan casing (2) comprising an upstream flange (21) directly connected to a downstream flange (31) of the air duct (3) by a plurality of mechanical components (4), an assembly characterized in that it comprises at least one stiffening element (5), positioned radially outside the air duct (3), the stiffening element (5) comprising a radially extending flat base (51), the base (51) being arched and connected to the downstream flange (31) of the air duct (3), upstream of said downstream flange (31) of the windsock (3), by at least five mechanical parts (4), the stiffening element being made up of the base (51). Assembly according to claim 1, wherein the stiffening element (5) is mounted in a dependent manner on the air sleeve (3). Assembly according to any one of claims 1 to 2, wherein the at least five mechanical components (4) are consecutive. Assembly according to any one of claims 1 to 3, wherein the base (51) extends circumferentially and parallel to the downstream flange (31) around a cylindrical section of the air sleeve (3) adjacent to the downstream flange (31). Assembly according to any one of claims 1 to 4, comprising a plurality of stiffening elements (5). Assembly according to any one of claims 1 to 5, wherein the plurality of stiffening elements (5) is distributed circumferentially outside the air sleeve (3), each stiffening element (5) being connected to the downstream flange (31) of the air sleeve (3). Assembly according to any one of claims 1 to 6, wherein the mechanical parts (4) are bolted parts. Assembly according to any one of claims 1 to 7, wherein the base (5) is connected to the downstream flange (31) of the air sleeve (3) by only five or six mechanical parts (4). Turbomachine (T), particularly for aircraft, comprising a fan housing (2) and a nacelle air duct (3) according to any one of claims 1 to 8, the turbomachine (T) extending along a longitudinal axis (X) and comprising at least one fan (1) mounted movably for rotation in the fan housing (2) along the longitudinal axis (X) so as to accelerate an upstream to downstream airflow.

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