FAN HOUSING FOR AN AIRCRAFT TURBOCHARGER

Description

Technical field of the invention

[0001] The present invention relates to the field of aircraft turbomachine blower housings. Technical background

[0002] There figure 1 partially represents a fan from an aircraft turbomachine.

[0003] Typically, a turbomachine comprises, from upstream to downstream, i.e. in the direction of gas flow, a blower, one or more compressors, a combustion chamber, one or more turbines, and a nozzle for ejecting the combustion gases exiting the turbine(s).

[0004] The blower 1 includes a blade wheel 2 which is surrounded by a blower housing 3, also called a retention housing because of its function of retaining the blades in case of breakage of the blades, or in case of entry of debris into the blower.

[0005] As can be seen on the figure 2The blower housing 3 has a generally cylindrical shape with axis of revolution A. It includes an annular mounting flange 3', 3" at each of its axial ends. These flanges 3', 3" are used to fix the housing 3 to annular walls of the turbomachine nacelle.

[0006] The fan casing 3 extends around the fan impeller 2. It comprises an internal cylindrical surface on which an annular layer 4 of abradable material is provided. This annular layer 4 of abradable material extends around and at a short radial distance from the blades, which, during operation, can rub against the material and wear it down. This optimizes the radial clearances between the blades and the surrounding fan casing 3, thus limiting gas leaks at the radially external tips or ends of the blades and thereby optimizing the turbomachine's performance. An example is described in document FR-A1-2913053.

[0007] In current technology, this annular layer of abradable material 4 consists of a solid or honeycomb-structured abradable support cartridge. This cartridge is generally riveted or screwed onto the blower housing.

[0008] There figure 3 is a schematic cross-section illustrating a blower housing 3 according to the prior art.

[0009] The blower housing is connected on one side to an air inlet sleeve 5, and, on the other side, to an intermediate housing ferrule 6. It also carries an upstream acoustic zone 7 and a downstream acoustic zone 8.

[0010] The blower housing 3 also includes an abradable support layer 4 in the form of a cartridge, positioned on an internal face of the blower housing 3, between the upstream acoustic zone 7 and the downstream acoustic zone 8.

[0011] One disadvantage of this abradable support cartridge 4 is that it locally increases the thickness of the blower housing 3 and, consequently, the weight of this blower housing 3.

[0012] In addition to this retention function, the blower housing 3 is also designed to: ensure mechanical continuity (of forces and moments) between the air inlet sleeve 5 and the intermediate casing ferrule 6; allow the fixing of panels of an aerodynamic duct delimited by the abradable support cartridge 4, the upstream acoustic zone 7 and the downstream acoustic zone 8 thus ensuring continuity of the aerodynamic duct; allow the fixing of equipment and supports known in themselves; meet the regulatory specifications for fire and leakage; allow the continuity of electrical current for lightning resistance, etc.

[0013] Furthermore, during operation, the two fan blades create dynamic stresses that include rotating pressure-vacuum pockets. These dynamic stresses excite the fan casing, causing acceleration and deformation. Indeed, the fan casing can exhibit a forced response to these dynamic stresses, potentially leading to its deterioration and thus reducing its lifespan.

[0014] The blower housing must therefore have sufficient mechanical strength to perform all these functions and withstand the dynamic stresses during blower operation. To this end, in the current state of the art, the blower housing includes, on one external face, metallic stiffeners 9 that reinforce the structure of the blower housing ( figure 2These stiffeners are generally an integral part of the housing, making it complex and expensive to produce. Furthermore, this adds to the weight of the blower housing.

[0015] US 2014 / 367920 A1, FR 3 037 854 A1, GB 2 442 112 A, WO 2014 / 066229 A1, WO 2016 / 027030 A1 and WO 2017 / 109403 A1 are also relevant prior art documents.

[0016] The present invention offers a simple, effective and economical solution to the aforementioned drawbacks of the prior art. Summary of the invention

[0017] To this end, the invention relates to a fan housing for an aircraft turbomachine, comprising an annular body extending around an axis A and equipped with an annular fixing flange at each of its axial ends, and an annular coating of abradable material, said body is made of a composite material, the housing further comprises an annular stiffener ensuring the reinforcement of the housing structure, the annular stiffener being disposed inside said body and which carries said coating, this stiffener having a substantially omega-shaped cross-section and comprising an annular wall of which a radially external face is radially separated from the body so that the annular space provided between the radially external face and a radially internal face of said body is kept empty, and of which a radially internal face receives said coating, the stiffener comprising annular tabs for fixing said wall to said body.

[0018] The blower housing according to the invention offers numerous advantages. In particular, it provides an abradable support while maintaining a reduced mass and offering improved retention capacity and overall stiffness. The omega shape of the stiffener provides a good compromise between the inertial stresses of the blower housing and the integration constraints of the stiffener within the blower housing.

[0019] Preferably and advantageously, the body is made from a preform of woven fibers densified by a polymer resin.

[0020] Such fibers make it possible to obtain a solution that is both lightweight and strong.

[0021] Advantageously, each of the legs has a general L-shaped cross-section and includes a first annular branch for fixing to the body, and a second annular branch for connecting the wall to the fixing branch, allowing the stiffener and the blower housing body to be joined.

[0022] According to a first example of implementation, the connecting branch is substantially perpendicular to the wall and / or the fixing branch.

[0023] According to another embodiment, the connecting arm is inclined relative to the wall and / or the fixing arm.

[0024] Thus, the energy absorption by the blower housing during operation of the blower blades is greater, thereby giving greater resistance and better robustness to the blower housing.

[0025] Advantageously, the stiffener has a substantially constant thickness, allowing its easy manufacture by known folding, draping and contouring techniques.

[0026] Advantageously, the wall has a diameter that varies along said axis A.

[0027] In this way, the stiffener can conform to the shape of the blower housing for better integration.

[0028] Preferably and advantageously, the connecting arms of the fixing lugs have different radial heights or dimensions relative to said axis A.

[0029] Thus, the stiffener conforms to the shape of the blower housing for better integration.

[0030] The invention further relates to a method for manufacturing a blower housing as described above, characterized in that it comprises: a) a step of making the body out of composite material, b) a step of making the stiffener, for example in carbon plies, c) a step of laying and fixing, for example by gluing, the stiffener inside the body, and d) a step of laying and fixing the abradable coating on the radially inner face of the stiffener.

[0031] The blower housing thus produced offers a mass reduction compared to blower housings of the prior art, particularly compared to the screwed or riveted solutions of the prior art, and with improved mechanical characteristics.

[0032] The invention also relates to an aircraft turbomachine, comprising a fan casing having at least one of the aforementioned characteristics.

[0033] As previously stated, such a turbomachine, due to the presence of a blower housing according to the invention, offers a gain in mass reduction, an improvement in stiffness and a gain in manufacturing time and, consequently, a gain in terms of cost. Brief description of the figures

[0034] The present invention will be better understood and other details, features, and advantages of the present invention will become more apparent upon reading the following description of a non-limiting example, with reference to the accompanying drawings in which: [ Fig. 1 ] There figure 1 already discussed shows a partial cross-sectional view of a turbomachine fan for aircraft according to the prior art; Fig. 2 ] There figure 2 The previously discussed illustration shows a perspective view of a blower housing according to the prior art; Fig. 3 ] There figure 3The previously discussed diagram shows a schematic partial cross-section of a blower housing according to the prior art; Fig. 4 ] There figure 4 is a perspective view of a blower housing according to the invention; [ Fig. 5 ] There figure 5 is a perspective cross-sectional view of an example embodiment of the stiffener equipping the blower housing according to the invention; [ Fig. 6 ] There figure 6 is a cross-sectional view of the stiffener illustrated in the figure 5 ; Fig. 7 ] There figure 7 shows a perspective cross-sectional view of an example embodiment of the blower housing according to the invention equipped with a stiffener as illustrated in the figure 5 ; Fig. 8 ] There figure 8 shows a cross-sectional view of the blower housing illustrated in the figure 7 ; Fig. 9 ] There figure 9 is a detailed view of another embodiment of the stiffener equipping the blower housing according to the invention; [ Fig. 10 ] There Figure 10is yet another detailed view of another example of the implementation of the stiffener equipping the blower housing according to the invention. Detailed description of the invention

[0035] With reference to the figure 4 , the housing 10 has an annular body 11 of generally substantially cylindrical shape with axis of revolution A.

[0036] In the present exposition and in the claims, the terms "internal" and "external" and "radial" are defined with respect to the axis A of the housing 10. The terms "upstream" and "downstream" are used with reference to the direction of flow of gas streams in a turbomachine.

[0037] The housing 10 includes an annular mounting flange 12a, 12b at each of its axial ends. These flanges 12a, 12b are used to fix the housing 10 to annular walls of a turbomachine nacelle with which it is fitted. In the case of an annular fan housing, these flanges 12a, 12b are used to fix the housing 10, on the one hand, to an air inlet sleeve of the turbomachine, and, on the other hand, to an intermediate housing ferrule of the turbomachine (not shown).

[0038] The annular body 11 is made of a composite material. For example, it is made from a preform of woven fibers, for example three-dimensional, woven, and densified by a polymer resin.

[0039] The annular body 11 of the housing 10 includes a radially internal annular surface 11' for receiving an annular coating of abradable material. That is, the radially internal annular surface 11' of the body 11 is for receiving an annular stiffener 13 covered with a layer of coating of abradable material 14.

[0040] The stiffener 13 comprises an annular wall 13a having a radially external face 13a' and a radially internal face 13a" and annular tabs 13b for fixing the wall 13a of the stiffener 13 to the body 11 of the housing 10.

[0041] The radially external face 13a' of the wall 13a of the stiffener is arranged opposite the radially internal face 11' of the body 11 of the housing 10 and is radially separated from the body 11 of the housing 10, so as to provide an annular space E.

[0042] The radially internal face 13a" of the wall 13a of the stiffener 13 receives the abradable coating layer 14.

[0043] Each of the annular lugs 13b for fixing the wall 13a of the stiffener 13 to the body 11 of the housing 10 has a generally L-shaped cross-section and includes a first annular branch 13b' for fixing to the body 11 of the housing 10, and a second annular branch 13b" for connecting the wall 13a of the stiffener 13 to said fixing branch 13b'.

[0044] According to the examples of achievement visible at figures 5 to 8 , the connecting branch 13b" is substantially perpendicular to the wall 13a of the stiffener 13 and / or to the fixing branch 13b'.

[0045] According to the examples of implementation illustrated in Figures 9 and 10 , the connecting arm 13b" is inclined with respect to said wall 13a of the stiffener 13 and / or to the fixing arm 13.

[0046] The connecting arm 13b" can thus be inclined at an angle α with respect to a normal to the radially external face 13a' of the wall 13a of the stiffener 13, this angle α being between 10° and 45°. The inclination angles of each connecting arm 13b" of the flanges 13b can be identical or different.

[0047] The annular stiffener 13 thus has a cross-section that is substantially omega (“Ω”) (in capital letters).

[0048] The stiffener 13 is located here in a central portion of the radially internal annular surface 11' of the body 11 of the housing 10 and is intended to extend opposite the top of the blower wheel blades.

[0049] The stiffener 13 extends continuously over the radially internal annular surface 11' of the body 11. The stiffener 13 has an axial length or dimension I, along axis A, which represents 40 to 60% of the length of the blower housing 10 and, in the example shown, 50% of the length of the blower housing 10. For example, the stiffener 13 has an axial dimension I of approximately 400 mm and a height h of approximately 30 mm. It also has a substantially constant thickness e. For example, the stiffener has a thickness e of approximately 5 mm.

[0050] The stiffener 13, for example, is made of carbon plies, giving it significant mechanical strength, namely increased stiffness through improved mechanical properties. The stiffener 13 thus has a mass of approximately 5.5 kg.

[0051] According to the illustrated but not limiting embodiment, the wall 13a of the stiffener 13 has a diameter that varies along axis A. Specifically, the wall 13a of the stiffener 13 comprises an upstream portion 13aa with diameter D1 and a downstream portion 13ac with diameter D2, the upstream and downstream portions 13aa and 13ac being connected by an intermediate portion 13ab. The diameter D1 of the upstream portion 13aa is greater than the diameter D2 of the downstream portion 13ac, therefore the diameter of the intermediate portion 13ab decreases between diameter D1 and diameter D2.

[0052] As can be seen on the figure 8 , the section of the wall 13a of the stiffener 13 thus reproduces substantially the section of the body 11 of the blower housing 10.

[0053] Interestingly, but by no means limitingly, the connecting arms 13" of the mounting brackets 13b have different heights h1, h2, or radial dimensions relative to the axis A of revolution of the blower housing 10. For example, the connecting arm 13b" from the mounting bracket 13b to the upstream annular lateral end of the upstream portion 13aa of the wall 13a of the stiffener 13 has a height h1 greater than the height h2 of the connecting arm 13b" from the mounting bracket 13b to the downstream annular lateral end of the downstream portion 13ac of the wall 13a of the stiffener 13.

[0054] The omega shape (“Ω”) of the stiffener 13 gives it significant mechanical robustness and a retention capacity allowing greater absorption of energy during operation of the turbomachine, while keeping empty the annular space E provided between the external face 13a' of the annular wall 13a of the stiffener 13 and the radially internal annular surface 11' of the body 11 of the housing 10, further adding to the gain in mass reduction of the blower housing 10 according to the invention.

[0055] Furthermore, the stiffener 13 thus has a simple and inexpensive design, unlike prior art honeycomb solutions which require pre-machining of the abradable honeycomb coating, a draping step, application of the abradable honeycomb coating, a trimming step, a machining step, and a bonding step of the abradable honeycomb coating to the blower housing. Moreover, the honeycomb coating forms a solid core, unlike the stiffener 13 of the present invention, which therefore requires less raw material for its manufacture, resulting in further cost savings.

[0056] The method for manufacturing a blower housing 10 according to the invention is simple, quick and therefore inexpensive to implement; it comprises the following steps: a) a step of making the body 11 in composite material, b) a step of making the stiffener 13, for example in carbon plies, c) a step of laying and fixing, for example by gluing, the stiffener 13 inside the body 11, and d) a step of laying and fixing the abradable coating 14 on the radially internal face 13a" of the stiffener 13.

[0057] For example, body 11 and stiffener 13 are produced by draping and trimming steps.

[0058] Furthermore, the bonding of the stiffener 13 and the body 11 of the housing 10 allows for a reduction in the mass of the assembly compared to a screwed or riveted solution.

[0059] Steps a) and b) can be carried out simultaneously, and the order of steps c) and d) can be reversed.

[0060] To ensure proper mounting interfaces between the stiffener 13 and the unmachined housing body 11 of the casing 10, directly from the molding, tooling could be used to conform the stiffener 13 to the correct dimensions relative to the blower casing 10 for which it is intended. A method for positioning the stiffener 13 on the blower casing 10, such as a laser or mounting jig, is also being considered.

[0061] Thus, according to the invention, the mechanical strength of the blower housing 10 is improved as well as the overall cycle time of the manufacturing process.

[0062] The present invention further relates to an aircraft turbomachine comprising from upstream to downstream, i.e. in the direction of gas flow, a blower, one or more compressors, a combustion chamber, one or more turbines, and a nozzle for ejecting the combustion gases exiting the turbine(s), the blower comprising a blade wheel surrounded by a blower housing 10 according to the invention.

Claims

1. A fan casing (10) for an aircraft turbomachine, comprising an annular body (11) extending about an axis (A) and equipped with an annular fastening flange (12a, 12b) at each of its axial ends, and an annular coating (14) made from abradable material, said body (11) being made from a composite material, characterized in that the fan casing (10) further comprises an annular stiffener (13) ensuring the reinforcement of the structure of the fan casing, the annular stiffener (213 being arranged inside said body (11) and carrying said coating (14), this stiffener (13) said stiffener (13) having a substantially omega-shaped cross-section and comprising an annular wall (13a), a radially outer face (13a') of which is separated radially from the body (11) so that the annular space (E) formed between the radially external face (13a) and a radially internal face (11') of said body (11) is kept empty, and a radially inner face (13a") of which receives said coating (14), the stiffener (13) comprising annular tabs (13b) for fastening said wall to said body.

2. The fan casing (10) according to the preceding claim, characterised in that said body (11) is made from a preform of woven fibres and densified by a polymeric resin.

3. The fan casing (10) according to one of the preceding claims, characterised in that each of said tabs (13b) is generally L-shaped in cross-section and comprises a first annular leg (13b') for fastening to the body (11), and a second annular leg (13b") for connecting the wall (13a) to said fastening leg (13b').

4. The fan casing (10) according to the preceding claim, characterised in that said connecting leg (13b") is substantially perpendicular to said wall (13a) and / or to said fastening leg (13b').

5. The fan casing (10) according to claim 3, characterized in that said connecting leg (13b") is inclined with respect to said wall (13a) and / or to said fastening leg (13b').

6. The fan casing (10) according to any one of the preceding claims, characterized in that said stiffener (13) has a substantially constant thickness (e).

7. The fan casing (10) according to one of the preceding claims, characterised in that said wall (13a) has a diameter which varies along said axis (A).

8. The fan casing (10) according to any one of the preceding claims, characterized in that the connecting legs (13b") of the fastening tabs (13b) have different heights (h1, h2) or radial dimensions with respect to said axis (A).

9. A method for producing a fan casing (10) according to any one of the preceding claims, characterised in that it comprises: a) a step for producing the body (11) in composite material, b) a step for producing the stiffener (13), for example in carbon folds, c) a step for placing and fastening, for example by gluing, the stiffener (13) inside the body (11), and d) a step for placing and fastening the abradable coating (14) on the radially inner face (13a") of the stiffener (13).

10. An aircraft turbomachine, characterised in that it comprises a fan casing (10) according to one of claims 1 to 8.