Duct arrangement for an air flow between annular casings of an aircraft propulsion assembly

Abstract

The present invention relates to a duct arrangement (6) for an air flow for an aircraft propulsion assembly (1), the arrangement (6) comprising: - an inner annular casing which extends around a longitudinal axis (X), - an outer annular casing which extends around the inner annular casing, the inner and outer annular casings defining therebetween a flow channel for an air flow (F2), and - a connecting device (60) connecting the inner annular casing to the outer annular casing and configured to transmit forces from one annular casing to the other, the connecting device (60) comprising elastically deformable members configured to allow relative movements between the inner and outer annular casings.

Description

[0001] DESCRIPTION

[0002] TITLE: ARRANGEMENT OF A DUCT FOR AN AIR FLOW BETWEEN ANNULAR CASINGS OF AN AIRCRAFT PROPULSION UNIT

[0003] Technical field of the invention

[0004] The technical field of the present invention is that of propulsion assemblies, for example for an aircraft, comprising a turbomachine and a nacelle surrounding the turbomachine.

[0005] The present invention relates in particular to an arrangement of an air flow duct for such an aircraft propulsion unit. In particular, this arrangement makes it possible to connect annular casings, respectively internal and external, of the aircraft propulsion unit.

[0006] Technical background

[0007] The state of the art includes in particular documents US-A1-2013 / 309070, US-A-5181675, US-A1-2009 / 134271 and US-A1-2013 / 051981. Known from the state of the art, as illustrated in FIG. 1, is a propulsion unit 1, in particular for an aircraft, comprising a turbomachine 2 and a nacelle 3 configured to be fixed around the turbomachine 2. The propulsion unit 1 extends along a longitudinal axis X.

[0008] Generally, the turbomachine 2 extends around a longitudinal axis which corresponds to the X axis. The turbomachine generally comprises several modules comprising, from upstream to downstream in the direction of gas flow, a fan, one or more compressor stages (for example a low-pressure compressor and a high-pressure compressor), a combustion chamber, one or more turbine stages (for example, a high-pressure turbine and a low-pressure turbine), and a gas exhaust nozzle. The fan, when it is at the front of the turbomachine 2, delivers a compressed air flow which is separated into two concentric annular flows: a primary air flow F1 and a secondary air flow F2 extending around the primary air flow F1.In Figure 1, the turbomachine 2 comprises annular casings 20, 22, 24, called internal (relative to the X axis), which can extend around the fan and the rest of the modules of the turbomachine 2 (namely the compressor and turbine stages, the combustion chamber and / or the gas exhaust nozzle).

[0009] Conventionally, the nacelle 3 also extends along a longitudinal axis which corresponds to the X axis. The nacelle 3 may comprise one or more annular casings 32, 34, called external (relative to the X axis), forming for example covers. The nacelle is thus a fairing element making it possible to protect the turbomachine. The external annular casing(s) 32, 34 are fixed to at least one of the internal annular casings 22, 24.

[0010] In Figure 1, the nacelle 3 comprises, from upstream to downstream in the direction of gas flow, an annular air inlet structure 30, a first external annular casing 32 surrounding the fan (and consequently the first internal annular casing 20 of the fan) and a second external annular casing 34 forming for example a thrust reverser in which the rest of the modules of the turbomachine are located.

[0011] The nacelle 3 (in particular the first and second external annular casings 32, 34) is generally mounted on at least one suspension 4a, 4b (for example an aircraft mast) of an aircraft structure (for example an aircraft wing or along an aircraft fuselage) in particular towards the rear of this aircraft. For this, fasteners 5a, 5b forming devices for connecting the propulsion unit 1 to the aircraft are located at two transverse planes: an upstream plane passing through a first internal annular casing 22 (which is designated the intermediate casing) and a downstream plane passing through a second internal annular casing 24 (which is designated the exhaust casing). The fasteners 5a, 5b are located in particular at the level of an annular flow vein V of the secondary air flow F2 of the propulsion unit 1. This annular flow vein V is delimited by the internal annular casings 20, 22, 24 and external annular casings 32, 34.To ensure downstream attachment, in the case of mounting on the fuselage, the attachment 5b comprises a first structural ring 50 at the level of the annular flow vein V of the secondary air flow F2, this first ring 50 being attached to the second external annular casing 34. The first ring 50 is connected by arms or connecting rods 51 to a ferrule or a second ring 52 attached to the second internal annular exhaust casing 24. Patent application EP-A1-2022973 describes an example of the structure of this downstream attachment of the propulsion unit to the aircraft.

[0012] The connection between the first and second rings 50, 52 may be in the form of radial arms distributed all around the axis X and rigidly fixed to the first and second rings 50, 52. This connection may also be in the form of connecting rods 51 inclined relative to the axis X, as illustrated in FIGS. 2a and 2b. The connecting rods 51 are fixed to the first and second rings 50, 52 by fasteners 53 of the clevis, ball joints and pin type. Such a fastener 53 is formed of two clevises, single or double, one secured to the end of the connecting rod 51 the other to a wall of the ring 50, 52 and crossed by a common pin. More particularly, the connecting rods 51 are arranged in pairs, the connecting rods 51 of each pair being tangent to the second ring 52 of the second inner annular exhaust casing 24 while being convergent on an attachment of the first ring 50 of the second outer annular casing 34.

[0013] Whether the connection is formed of radial arms or connecting rods 51, it is hyperstatic; inertial forces, for example generated by the turbomachine 2, will thus pass through all the arms or connecting rods 51. In particular, these inertial forces are mainly generated by the mass of a rear part of the turbomachine (namely that of a high-pressure body generally composed of a high-pressure compressor and a high-pressure turbine of the turbomachine). In addition, this rear part of the turbomachine may be cantilevered from the second internal annular casing 24, implying that it remains sensitive to inertial stresses, in particular to inertial stresses in the radial planes passing through the attachment 5b. In the solutions of the prior art, all the elements of the connection: axes, clevises, ball joints, connecting rods or arms, are dimensioned to mechanically resist these inertial forces.This makes it possible to radially stiffen the rear part of the turbomachine. Furthermore, since the inertial forces potentially pass through all the arms or connecting rods 51, the first ring 50 should also be able to withstand these loads over its entire circumference. The first ring 50 is therefore dimensioned accordingly. The mass of the connecting device (i.e. attachment 5b) is consequently high. Thus, the connecting device according to such a configuration may have the disadvantage of having a significant radial and axial size due to the high number of connecting elements.

[0014] In addition, it may be necessary for the 5b fastener to also meet the following requirements:

[0015] - a given radial stiffness to be able to limit the movements of the high pressure body of the turbomachine and transmit the aforementioned inertial forces,

[0016] - a tolerance to relative axial expansion between the inside and the outside of the turbomachine in contact with, respectively, the primary flow at high temperature and the secondary air flow at colder temperature, and

[0017] - avoid obstruction or disruption of the flow of secondary air in the annular flow vein so as not to impact the performance of the turbomachine.

[0018] In this context, it is interesting to propose a solution to overcome the drawbacks of the prior art.

[0019] In particular, the present invention aims to propose an arrangement for a duct for an air flow between inner and outer annular casings for an aircraft propulsion unit which, while ensuring the absorption of the thrust forces generated by one of the annular casings, makes it possible to reduce the radial and / or axial size of this arrangement.

[0020] The present invention also aims that this airflow duct arrangement in the aircraft propulsion assembly makes it possible to limit the disturbance of the airflow flow in an airflow flow vein defined between the inner and outer annular casings.

[0021] Summary of the invention

[0022] The present invention thus provides an airflow duct arrangement for an aircraft propulsion unit, the arrangement comprising:

[0023] - an internal annular casing which extends around a longitudinal axis X,

[0024] - an outer annular casing extends around the inner annular casing, the inner and outer annular casings defining between them a flow path for an air stream, and

[0025] - a connecting device connecting the inner annular casing to the outer annular casing and configured to transmit forces from one annular casing to the other.

[0026] According to the invention, said connecting device comprises elastically deformable members configured to allow relative movements between the internal and external annular casings.

[0027] Thus, this solution makes it possible to achieve the aforementioned objective(s). In general, the invention makes it possible to simplify the connection between the inner and outer annular casings, thereby reducing its radial and / or axial size. To this end, the connecting device of the invention proposes to integrate elastically deformable members to replace the numerous articulated, rigid, hyperstatic and bulky parts of the prior art. The particular dimensions of the elastically deformable members promote radial and / or axial movement between the inner and outer annular casings, while ensuring the primary functions of the connecting device (namely attaching the annular casings together and transmitting forces, for example of the inertial type, from one annular casing to the other). In this way, the overall mass of the arrangement of the invention is significantly reduced.In addition, the assembly of the connecting device of the invention between the annular casings is easier and simpler to carry out for an operator.

[0028] Furthermore, the connecting device of the invention installed at the level of a flow vein of an air flow (in particular a secondary air flow) in the propulsion unit makes it possible not to disturb (or to a very small extent) the flow of this air flow. In this way, the overall performance of the aircraft propulsion unit is optimized.

[0029] The invention therefore has the advantage of being based on a simple design, offering very high reliability, and with little penalty in terms of cost and size.

[0030] The term "elastically deformable member" means a part or at least a portion of this part capable of deforming (for example stretching, compressing, bending, etc.) reversibly when forces are applied to it to transmit these forces between at least two elements. This part or portion of a part has in particular a certain degree of flexibility to allow relative movements between the two elements. This flexibility can be obtained by particular shapes and dimensions and / or an elastically deformable material. Thus, parts or portions of parts which are articulated without elastic deformation (such as connecting rods, link rods, ball joints, etc.) cannot correspond to the elastically deformable members of the invention.

[0031] The conduit arrangement according to the invention may comprise one or more of the following features, taken in isolation from each other or in combination with each other:

[0032] - each of the elastically deformable members is chosen from a spring, a bar and a pad;

[0033] - the pads are made of an elastically deformable material, or the springs are embedded in an elastically deformable material, for example the elastically deformable material is of the elastomer or fluoroelastomer type;

[0034] - said connecting device comprises two rings, respectively internal and external, connected to each other by so-called connecting bars, the internal ring being fixed to the internal annular casing, the external ring being fixed to the external annular casing and the connecting bars forming said elastically deformable members;

[0035] - the inner and outer rings and the connecting bars are formed from a single piece;

[0036] - each of the connecting bars is inclined tangentially relative to the internal annular casing, for example each of the connecting bars extends at an angle of inclination relative to the internal annular casing which is between 10° and 45°, this angle being measured in a plane P tangent to the X axis;

[0037] - the connecting device comprises a slot at a connecting interface between each of the connecting bars and at least one of the inner and outer rings;

[0038] - each bar has a thickness less than the thickness of one of the inner and outer rings, these thicknesses being measured along the X axis;

[0039] - said connecting device consists of an annular row of springs, one of the two ends of the springs being fixed to one of the annular casings and the other of the two ends of the springs bearing on the other of the annular casings;

[0040] - said connecting device comprises two rings, respectively, internal and external connected to each other by springs, in which the internal ring is fixed to the internal annular casing, the external ring is fixed to the external annular casing, and the springs forming said elastically deformable members;

[0041] - one of said annular casings or said inner and outer rings comprise members for fixing to the springs; -- each of the springs is embedded in an elastically deformable material, for example elastomer;

[0042] - said connecting device comprises an annular row of pads, in which each of the pads comprises a first portion bearing on one of the annular casings and a second portion fixed to the other of the annular casings, and the pads forming said elastically deformable members;

[0043] - the connecting device comprising the elastically deformable members is made from a single piece;

[0044] - the connecting device is formed of several parts assembled together, at least one of the parts of which comprises elastically deformable members;

[0045] -- the elastically deformable members are distributed regularly around the X axis;

[0046] -- the inner and outer rings comprise fixing holes, these fixing holes allowing the passage, for example, of screws to fix the inner and outer rings to the annular casings, respectively, inner and outer;

[0047] -- the outer ring is separated from the inner ring by a distance of between 15 and 50 mm, this distance being measured along a plane perpendicular to the X axis;

[0048] -- the internal ring has a first thickness of between 1 and 4 mm, the first thickness being measured along the X axis;

[0049] -- the outer ring has a second thickness of between 1 and 4 mm, the second thickness being measured along the X axis;

[0050] -- each of the connecting bars has a third thickness of between 1 and 3 mm, the third thickness being measured along the X axis;

[0051] - each of the spring attachment members is a lug or a needle; -- the attachment member may be formed or attached to the inner and outer rings or one of the inner and outer annular casings. The invention also relates to a propulsion assembly for an aircraft comprising a turbomachine, and a nacelle surrounding at least part of the turbomachine. This propulsion assembly comprises an arrangement according to one of the particularities of the invention, the inner annular casing of this arrangement being formed by a casing of the turbomachine and the outer annular casing being formed by a nacelle cowl or a nozzle.

[0052] Brief description of the figures

[0053] The invention will be better understood and other details, characteristics and advantages of the invention will appear more clearly on reading the following description given by way of non-limiting example and with reference to the appended drawings in which: Figure 1 is a schematic perspective view of an aircraft propulsion unit according to the prior art, Figure 2a is a schematic perspective view of a device for connecting the inner and outer annular casings of the aircraft propulsion unit of Figure 1, Figure 2b is a schematic and axial sectional view of the connecting device of Figure 2a, Figure 3 is a schematic perspective view of an aircraft propulsion unit according to the invention, Figure 4 is a schematic axial sectional view of a connecting device according to a first embodiment of the invention, Figure 5a is an enlarged and partial view schematically showing in axial section the connecting device of Figure 4,Figure 5b is an enlarged and partial view schematically showing in perspective the connecting device of Figure 4 or Figure 5a, Figure 6 is a schematic perspective view of an arrangement for the aircraft propulsion unit of Figure 3 comprising the connecting device of Figures 4, 5a and 5b, Figure 7a is a schematic axial sectional view of a connecting device according to a second embodiment of the invention, Figure 7b is an enlarged view schematically showing in perspective a part of the connecting device of Figure 7a, Figure 8a is a schematic axial sectional view of an arrangement for the aircraft propulsion unit of Figure 3 comprising a connecting device according to a third embodiment of the invention, Figure 8b is an enlarged view schematically showing in axial section a part of the connecting device of Figure 8a,Figure 9a is a schematic axial sectional view of an arrangement for the aircraft propulsion unit of Figure 3 comprising a connecting device according to a fourth embodiment of the invention, Figure 9b is an enlarged view schematically representing in perspective and from above a part of the connecting device of Figure 9a, Figure 9c is an enlarged view schematically representing in section a part of the connecting device of Figure 9a or Figure 9b.,

[0054] Elements having the same functions in different implementations have the same references in the figures.

[0055] Detailed description of the invention

[0056] By convention in the present application, the terms "inner" and "outer", and "internal" and "external" are defined radially relative to a longitudinal axis (such as that of an aircraft propulsion unit). Thus, a cylinder extending along the longitudinal axis has an inner face facing the axis of the engine and an outer surface, opposite its inner surface. "Axial" or "axially" means any direction parallel to the longitudinal axis. Similarly, the terms "upstream" and "downstream" are defined relative to the direction of air circulation in the aircraft propulsion unit. Figures 1, 2a and 2b have been described in the technical background of the present invention. These figures illustrate an aircraft propulsion unit according to the prior art and a device for connecting the inner and outer annular casings of this aircraft propulsion unit.

[0057] The invention applies in a general and non-limiting manner to a propulsion unit 1, in particular for an aircraft, illustrated for example in Figure 3.

[0058] This propulsion assembly 1 comprises a turbomachine 2 and a nacelle 3 surrounding at least part of the turbomachine 2. The propulsion assembly 1 extends along a longitudinal axis X in figure 3.

[0059] The turbomachine 2 can extend around a longitudinal axis which corresponds to the X axis. This turbomachine 2 can be configured to be fixed to a structure of the aircraft (for example an aircraft wing or along an aircraft fuselage).

[0060] The turbomachine 2 generally comprises several modules comprising, from upstream to downstream in the direction of gas flow, a fan, one or more compressor stages (for example a low pressure compressor and a high pressure compressor), a combustion chamber, one or more turbine stages (for example, a high pressure turbine and a low pressure turbine), and possibly a gas exhaust nozzle.

[0061] The turbomachine 2 may be a dual-flow turbojet. In this configuration, the fan, generally at the front of the turbomachine 2, delivers a compressed air flow which is separated into two concentric annular flows: a primary air flow F1 and a secondary air flow F2 extending around the primary air flow F1.

[0062] The turbomachine 2 comprises several annular casings 20, 22, 24, called internal (relative to the X axis), such as at least one of the following casings:

[0063] - an internal annular casing 20 upstream extending around the fan,

[0064] - a first internal annular casing 22 (which is designated intermediate casing) extending over an upstream part of the rest of the modules of the turbomachine 2 (namely the compressor stage in the example of figure 3), and

[0065] - a second internal annular casing 24 (which is designated exhaust casing) extending over a downstream part of the rest of the modules (namely the combustion chamber, the turbine stage and possibly the gas exhaust nozzle in the example of figure 3).

[0066] Concerning the nacelle 3, it can also extend along a longitudinal axis which corresponds to the X axis. The nacelle 3 (and consequently the propulsion unit 1) can have an external diameter D3 measured along a plane perpendicular to the X axis. This external diameter D3 can be less than 0.5 meters.

[0067] The nacelle 3 can be mounted on at least one suspension 4a, 4b (for example an aircraft mast) of the aircraft structure, in particular towards the rear of this aircraft.

[0068] The nacelle 3 may comprise one or more annular casings 32, 34, called external (relative to the X axis). With reference to FIG. 3, the nacelle 3 comprises, from upstream to downstream in the direction of gas flow, an annular air inlet structure 30, a first external annular casing 32 surrounding the fan, and a second external annular casing 34 forming, for example, a thrust reverser in which the rest of the modules of the turbomachine are located (namely the compressor and turbine stages, the combustion chamber and possibly the gas exhaust nozzle in the example of FIG. 3). These external annular casings 32, 34 may form, for example, annular cowls of the nacelle 3.

[0069] The propulsion assembly 1 may comprise an ejection nozzle comprising an external annular structure forming an annular cover which is distinct from one of the covers of the nacelle 3. In this configuration (not illustrated in the figures), the nacelle surrounding the turbomachine is therefore extended by this ejection nozzle. This ejection nozzle extends at least partly around the gas exhaust nozzle of the turbomachine.

[0070] In the example of Figure 3 and in a non-limiting manner, the first external annular casing 32 extends around the internal annular casing 20 upstream of the fan, the second external annular casing 34 extends around the first and second internal annular casings 22, 24.

[0071] The propulsion unit 1 comprises an arrangement 6 for ducting an air flow (in particular the secondary air flow F2). In particular, the arrangement 6 is located at a flow path of the secondary air flow F2 of the propulsion unit 1. This flow path may extend around the axis X and may be delimited by the internal annular casings 20, 22, 24 and external annular casings 32, 34 in the example of FIG. 3. The arrangement 6 makes it possible in particular to connect one of the internal annular casings 20, 22, 24 with one of the external annular casings 32, 34.

[0072] In a non-limiting manner, the present application will now describe the arrangement 6 with reference to the connection between the second internal annular casing 24 of the turbomachine 2 and the second external annular casing 34 of the nacelle 3. This second external annular casing 34 may be one of the annular nacelle cowls 3 or the ejection nozzle of the propulsion unit 1. Alternatively, the arrangement 6 may allow the connection between the first internal annular casing 22 and the second external annular casing 34 (not illustrated in the figures).

[0073] Thus, arrangement 6 includes:

[0074] - the second internal annular casing 24 which extends around the X axis,

[0075] - the second outer annular casing 34 which extends around the second inner annular casing 24, and

[0076] - a connecting device 60 connecting the second inner annular casing 24 to the second outer annular casing 34 and configured to transmit forces from one annular casing to the other. One of the particularities of the invention is that the connecting device 60 comprises elastically deformable members 600 configured to allow relative movements between the second inner and outer annular casings 24, 34.

[0077] The connecting device 60 may be a single part (i.e. made of one material) comprising the elastically deformable members 600 (such as the device of FIGS. 4 to 6, and possibly FIGS. 8a, 8b, 9a to 9c). Alternatively, the connecting device 60 may be formed of several parts assembled together, at least one of the parts comprising the elastically deformable members 600 (such as the device of FIGS. 7a to 9c).

[0078] Each of the elastically deformable members 600 can be chosen from a bar 624 (Figures 4 to 6), a spring 644 (Figures 7a, 7b, 8a and 8b) and a pad 664 (Figures 9a and 9c).

[0079] The bars 624 can each be made of a metallic material (for example steel).

[0080] The pads 664 may each be made of an elastically deformable material. For example, the elastically deformable material is of the elastomer or fluoroelastomer type. Preferably, the elastically deformable material is chosen to withstand a high temperature of up to 250°C, such as fluoroelastomer.

[0081] Advantageously, the springs 644 may be embedded (or otherwise said wrapped or coated) in an elastically deformable material, for example elastomer. The elastically deformable material makes it possible to provide a damping function to these springs to, for example, reduce the intensity of vibrations transmitted to the connecting device 60 by the second internal annular casing 24.

[0082] The present application will now describe the different possible configurations of the elastically deformable members 600 making up the connecting device 60 of the invention with reference to Figures 4 to 9c. Figures 4 to 6 illustrate a first embodiment of the connecting device 60 of the arrangement 6.

[0083] With reference to figures 4, 5a and 5b, the connecting device 60 of the first embodiment may be a part of revolution extending around a longitudinal axis A. This axis A corresponds substantially to the axis X when the arrangement 6 is installed in the aircraft propulsion assembly 1.

[0084] The connecting device 60 may comprise two rings, respectively, internal 620 and external 622 connected to each other by bars 624, called connecting bars. The connecting bars 624 are configured to allow relative movements between the internal and external rings 620, 622 (and consequently also between the second internal and external annular casings 24, 34) and thus form the elastically deformable members 600 of the first embodiment.

[0085] The inner ring 620 may comprise first orifices 620a. These first orifices 620a allow the passage of screws to fix this inner ring 620 to the second inner annular casing 24. Thus, the inner ring 620 may form a first fixing flange of the connecting device 60 to the second inner annular casing 24.

[0086] The inner ring 620 may have a first thickness E620, this first thickness E620 being measured along the axis A. This first thickness E620 may be between 1 and 4 mm. For example, the first thickness E620 is approximately 2 mm.

[0087] The internal ring 620 may have a first diameter D620, this first diameter D620 being measured along a plane perpendicular to the axis A. This first diameter D620 may be between 250 mm and 350 mm.

[0088] The internal ring 620 may have a first width I620 measured relative to a plane transverse to the axis A. This first width I620 may be between 15 and 25 mm.

[0089] The outer ring 622 may extend in particular coaxially around the inner ring 620. The outer ring 622 may be distant from the inner ring 620 by a distance d. This distance d may be between 15 and 50 mm. For example, the distance d may be approximately 17 mm. The distance d is measured along a plane perpendicular to the axis A.

[0090] The outer ring 622 may comprise second orifices 622a. These second orifices 622a allow the passage of screws to fix this outer ring 622 to the second outer annular casing 34. Thus, the outer ring 622 may form a second fixing flange of the connecting device 60 to the second outer annular casing 34.

[0091] The outer ring 622 may have a second thickness E622, this second thickness E622 being measured along the axis A. This second thickness E622 may be between 1 and 4 mm. For example, the second thickness E622 is approximately 2 mm. The first and second thicknesses E620, E622 may be identical or different.

[0092] The outer ring 622 may have a second diameter D622, this second diameter D622 being measured along a plane perpendicular to the axis A. This second diameter D622 may be between 320 mm and 500 mm. The first diameter D620 may therefore be less than the first diameter D622.

[0093] The outer ring 622 may have a second width I622 measured relative to a plane transverse to the axis A. The first I620 and second I622 widths may be identical or different. This second width I622 may be between 15 and 25 mm.

[0094] The connecting device 60 may comprise between three and twelve connecting bars 624. The number of connecting bars 624 may vary depending on the dimensions (i.e., the diameter, the width and / or the thickness) of the inner and outer rings 620, 622 and / or the desired radial stiffness in operation. The example of FIG. 4 illustrates eight connecting bars 624 connecting the inner and outer rings 620, 622. These eight connecting bars 624 are distributed regularly around the axis A.

[0095] Each of the connecting bars 624 may have a third thickness E624, this third thickness E624 being measured along the axis A. This third thickness E624 may be less than the first and second thicknesses E620, E622. This makes it possible to limit the stresses at the ends of the connecting bars, for example in the event of differential axial movement between the inner and outer rings. Advantageously, the third thickness E624 may be at least 1 mm. The third thickness E624 may be between 1 and 3 mm. For example, the third thickness E624 is approximately 1.6 mm.

[0096] Each of the connecting bars 624 may comprise a first length L624, this first length L624 being measured in the axis of the bar in the example of figure 5b. This first length L624 may be between 50 mm and 180 mm.

[0097] Each of the connecting bars 624 may have a third width I624 measured relative to a plane transverse to the axis A. The third width 1624 may be between 10 and 30% of the first 1620 and second I622 widths. This third width I624 may be between 2 and 8 mm.

[0098] Each of the connecting bars 624 may be inclined tangentially relative to the inner ring 620. Each of the connecting bars 624 may extend at an angle of inclination α relative to the inner ring 620 that is between 10° and 45°, this angle α being measured in a plane P tangent to the axis A (or to the axis X). For example, the angle α is between 10° and 20°, as illustrated in the example of FIG. 5a.

[0099] The connecting device 60 may comprise a connecting interface 625 between each of the connecting bars 624 and at least one of the inner and outer rings 620, 622. A slot 626 may be located at this connecting interface 625. The slots 626 also make it possible to reduce the stresses at the ends of the connecting bars 624, for example in the event of axial and / or radial movement between the inner and outer rings 620, 622. These slots 626 further make it possible to increase the first length L624 of the connecting bars 624, and thus reduce the radial stiffness of the connecting device 60.

[0100] Each slot 626 may have a second length L626, this second length L626 being measured in the axis of the slot in the example of figure 5b. This second length L626 may be between 5 and 45% of the first length l_624. The second length L626 may be between 15 and 50 mm. For example, the second length L626 may be approximately 25 mm.

[0101] Each slot 626 may have a fourth width I626 measured relative to a plane transverse to the axis A. The fourth width I626 may be between 2 and 6 mm. For example, the fourth width I626 may be between 2 and 4 mm.

[0102] The dimensions of the slots 626 may vary depending on the dimensions (such as the distance d or the first and second diameters D620, D622) of the inner and outer rings 620, 622 and / or the angle a. For example, when the distance d between the inner and outer rings 620, 622 is about 17 mm and the angle a is about 13°, the dimensions of the slots 626 may be about:

[0103] - 25 mm for the second length L626,

[0104] - 1 mm for radius r626, and

[0105] - between 2 and 4 mm for the fourth width I626.

[0106] The inner and outer rings 620, 622 and the connecting bars 624 may be formed from a single piece (i.e., made from one material).

[0107] The connecting device 60 of the first embodiment (i.e. the bars 624) can be made of metal (for example steel).

[0108] With reference to Figure 6, the present application will now describe the assembly of the connecting device 60 according to the first embodiment in the arrangement 6 of the aircraft propulsion assembly 1.

[0109] As mentioned above, the inner ring 620 is connected to the second inner annular casing 24 of the turbomachine 2, for example by first fixing screws V1, the outer ring 622 is fixed to the second outer annular casing 34 of the nacelle 3, for example by second fixing screws V2. In the example of FIG. 6, the inner ring 620 is interposed between two first annular walls, respectively, upstream 24a and downstream 24b of the second inner annular casing 24. The outer ring 622 is interposed between two second annular walls, respectively, upstream 34a and downstream 34b of the second outer annular casing 34.

[0110] Furthermore, the connecting device 60 (in particular the external ring 622) and the second external annular casing 34 can be connected to the suspension 4b of the aircraft.

[0111] Thus, the radial and / or axial size of the connecting device 60 of the invention is significantly reduced compared to the size of the attachment 5b of the prior art (Figures 2a and 2b). Furthermore, the connecting device 60 of the invention (in particular the connecting bars) does not disturb (or even very slightly) the flow of the secondary air flow F2 during operation.

[0112] Figures 7a and 7b illustrate a second embodiment of the connecting device 60 of the arrangement 6.

[0113] The connecting device 60 of the second embodiment differs from the connecting device 60 of the first embodiment by the elastically deformable members 600. Indeed, the connecting bars 624 of the first embodiment are replaced by springs 644.

[0114] With reference to figures 7a and 7b, the connecting device 60 of the second embodiment can also be a part of revolution extending around a longitudinal axis A. This axis A corresponds substantially to the axis X when the arrangement 6 is installed in the aircraft propulsion assembly 1.

[0115] The connecting device 60 may comprise the two inner rings 620 and outer rings 622 described in the first embodiment. These two inner rings 620 and outer rings 622 are connected to each other by springs 644 in the connecting device 60 of the second embodiment. The springs 644 are configured to allow relative movements between the inner and outer rings 620, 622 (and consequently also between the second inner and outer annular casings 24, 34) and thus form the elastically deformable members 600 of the second embodiment. The connecting device 60 may comprise between three and twenty springs 644. The number of springs 644 may vary depending on the dimensions (namely the diameters D620, D622, the widths I620, I622 and / or the thicknesses E620, E622) of the inner and outer rings 620, 622 and / or the desired radial stiffness in operation.The example of Figure 7a illustrates fourteen springs 644 connecting the inner and outer rings 620, 622. These springs 644 are distributed regularly around the axis A.

[0116] Each of the springs 644 may include a first end 644a and a second end 644b that is opposite the first end 644a. The first and second ends 644a, 644b are formed as a single piece (i.e., integrally formed).

[0117] Each of the springs 644 may be embedded in an elastically deformable material, for example an elastomer, in order to provide a damping capacity for the connecting device 60.

[0118] The inner 620 and outer 622 rings may each comprise attachment members 646 to the springs 644. The attachment members 646 may be formed or attached to the inner 620 and outer 622 rings. The attachment members 646 and the inner 620 and outer 622 rings may be one-piece (i.e., integrally formed). For example, the attachment members 646 may each be a lug, a needle, or any other element for attaching and retaining the spring to one of the inner and outer rings 620, 622.

[0119] Figure 7b illustrates lugs as an example of a fastener 646 that may be formed or attached to the inner and outer rings 620, 622. The first and second ends 644a, 644b of each spring 644 may be connected to the lugs of the inner and outer rings 620, 622.

[0120] Similar to the arrangement 6 of Figure 6, the inner and outer rings 620, 622 are fixed, respectively, to the second inner 24 and outer 34 annular casings for example by the first V1 and second V2 fixing screws. The connecting device 60 of the second embodiment can be assembled between the second inner and outer annular casings 24, 34 by keeping the springs 644 compressed, then the springs 644 are released.

[0121] In particular, the springs 644 can be formed or mounted compressed during the manufacture of the connecting device 60, and kept prestressed between the inner 620 and outer 622 rings. When assembling the inner 620 and outer 622 rings, respectively, on the second inner 24 and outer 34 annular casings, this connecting device 60 of the second embodiment can thus be in one piece.

[0122] The radial and / or axial size of the connecting device 60 of the second embodiment is significantly reduced, and this connecting device 60 (in particular the springs 644) does not disturb (or even very slightly) the flow of the secondary air flow F2 in the aircraft propulsion assembly 1 in operation.

[0123] Figures 8a and 8b illustrate a third embodiment of the connecting device 60 of the arrangement 6.

[0124] The connecting device 60 of the third embodiment differs from the connecting device 60 of the second embodiment by the mounting of the elastically deformable members 600 in the arrangement 6. In particular, the springs 644 of the third embodiment are arranged directly on the second inner 24 and outer 34 annular casings (i.e. without the inner 620 and outer 622 rings).

[0125] With reference to Figure 8a, the connecting device 60 of the third embodiment may consist of one or more annular row(s) of springs 644. This annular row of springs 644 may comprise the springs 644 distributed regularly around the axis X.

[0126] The springs 644 of the connecting device 60 of the third embodiment may be similar to those described with reference to the connecting device 60 of the second embodiment. Thus, the springs 644 are configured to allow relative movements between the second inner and outer annular casings 24, 34 and thus form the elastically deformable members 600 of the third embodiment.

[0127] The connecting device 60 may comprise between three and twenty springs 644. The number of springs 644 may vary depending on the dimensions (for example the diameters) of the second inner and outer annular casings 24, 34 and / or the desired radial stiffness in operation. The example of FIG. 8a illustrates thirteen springs 644 connecting the second inner and outer annular casings 24, 34. These springs 644 are distributed regularly around the X axis.

[0128] Each of the springs 644 may be embedded in an elastically deformable material, for example an elastomer, in order to provide a damping capacity for the connecting device 60.

[0129] In particular, one of the first and second ends 644a, 644b of each spring 644 may be fixed (or connected) to one of the second inner and outer annular casings 24, 34, and the other of the first and second ends 644a, 644b of each spring 644 may be in abutment (or in contact) against the other of the second inner and outer annular casings 24, 34. Each of the first ends 644a may be fixed to one of the second inner and outer annular casings 24, 34, and each of the second ends 644b may be in abutment (or in contact) against the other of the second inner and outer annular casings 24, 34. Preferably, each second end 644b may be able to slide on the corresponding second annular casing.

[0130] One of the second inner 24 and outer 34 annular casings may comprise the fixing members 646 for the springs 644, as described above with reference to FIGS. 7a and 7b. These fixing members 646 may be welded or attached (for example by screws) to one of the second inner and outer annular casings 24, 34. By way of example, the fixing members 646 may each be a lug, a needle or any other element making it possible to fix and retain the spring on one of the second inner and outer annular casings 24, 34.

[0131] Figure 8b illustrates in a non-limiting manner a lug as an example of a fixing member 646 which can be formed or attached to the second internal annular casing 24. The first end 644a of the springs 644 is fixed to the second internal annular casing 24 by means of the lug forming the fixing member 646, and the second end 644b of the springs 644 is in abutment on the second external annular casing 34.

[0132] In the arrangement 6 comprising the connecting device 60 according to the third embodiment, the springs 644 (or the annular row of springs 644) are mounted between the second inner 24 and outer 34 annular casings by compression, then the springs 644 are released.

[0133] The radial and / or axial size of the connecting device 60 of the third embodiment is significantly reduced, and this connecting device 60 (in particular the springs 644) does not disturb (or even very slightly) the flow of the secondary air flow F2 in the aircraft propulsion assembly 1 in operation.

[0134] Figures 9a, 9b and 9c illustrate a fourth embodiment of the connecting device 60 of the arrangement 6.

[0135] The connecting device 60 of the fourth embodiment differs from the connecting device 60 of the first to third embodiments by the elastically deformable members 600. Indeed, the connecting bars 624 of the first embodiment and the springs 644 (or annular row of springs 644) of the second and third embodiments are replaced by pads 664 as elastically deformable members 600.

[0136] With reference to Figures 9a to 9c, the connecting device 60 of the fourth embodiment comprises one or more annular row(s) of pads 664. This annular row of pads 664 may comprise pads 664 distributed regularly around the axis X. The pads 664 may be arranged directly between the second inner and outer annular casings 24, 34.

[0137] The pads 644 are configured to allow relative movements between the second inner and outer annular casings 24, 34 and thus form the elastically deformable members 600 of the fourth embodiment. In addition, the pads 664 also provide a damping function to, for example, reduce the intensity of vibrations transmitted to the connecting device 60 by the second inner annular casing 24.

[0138] Each of the pads 664 may comprise a first portion 664a connected to a second portion 664b opposite this first portion 664a. The first and second portions 664a, 664b are preferably formed in a single piece (i.e., integrally formed).

[0139] The first portion 664a of the pads may bear on one of the second inner and outer annular casings 24, 34, and the second portion 664b of the pads may be fixed (or connected) to the other of the second inner and outer annular casings 24, 34, for example by third fixing screws V3. Preferably, each first portion 664a of the pads may be able to slide on the corresponding second annular casing.

[0140] With reference to Figure 9c, each of the pads 664 may comprise an opening 664c for housing at least a portion of the third fixing screw V3. The opening 664c may have a general “T” shape in axial section. In a non-limiting manner, a head of the third fixing screws V3 may be entirely embedded in this opening 664c (so that the head of the third screws V3 does not extend beyond the first portion 664a and is not in contact with one of the second annular casings), a portion of a threaded portion of the third fixing screws V3 may be housed in this opening 664c and another portion of this threaded portion may be fixed in the second internal annular casing 24.

[0141] With reference to FIG. 9b, each of the pads 664 may have a general shape having an aerodynamic profile (also designated by the term NACA profile). This makes it possible in particular to improve the flow of the secondary air flow F2 passing through the pads 664 when the connecting device 60 is in operation in the aircraft propulsion assembly 1.

[0142] The connecting device 60 may comprise between three and twenty pads 664. The number of pads 664 may vary depending on the dimensions (for example the diameters) of the second inner and outer annular casings 24, 34 and / or the desired radial stiffness in operation. The example in FIG. 9a illustrates twelve pads connecting the second inner and outer annular casings 24, 34. These pads 664 are distributed regularly around the X axis.

[0143] The pads 664 may be made of an elastically deformable material (for example, elastomer or fluoroelastomer).

[0144] In the arrangement 6 comprising the connecting device 60 according to the fourth embodiment, the pads 664 (or the annular row of pads 664) can be mounted between the second inner 24 and outer 34 annular casings by compression, then the pads 664 can be released. The radial and / or axial size of the connecting device 60 of the fourth embodiment is also significantly reduced, and this connecting device 60 (in particular the pads 664) does not disturb (or even very slightly) the flow of the secondary air flow F2 in the aircraft propulsion assembly 1 in operation.

[0145] The duct arrangement of the invention generally makes it possible to connect two coaxial elements together and defining between them a flow path for an air flow, in which one of the two elements may be an internal annular casing and the other of the two elements may be an external annular casing. The internal annular casing may be at least one of the annular casings of a turbomachine and the external annular casing may be at least one of the annular casings of a nacelle (forming for example an annular cowl of the nacelle) or of an exhaust nozzle (forming for example an annular cowl or another annular component of the exhaust nozzle) of the propulsion unit, in particular of an aircraft.

Claims

CLAIMS 1. Arrangement (6) for a conduit of an air flow for an aircraft propulsion unit (1), the arrangement (6) comprising: - an internal annular casing (24) which extends around a longitudinal axis (X), - an outer annular casing (34) which extends around the inner annular casing (24), the inner and outer annular casings (24, 25) defining between them a flow path for an air flow (F2), and - a connecting device (60) connecting the inner annular casing (24) to the outer annular casing (34) and configured to transmit forces from one annular casing to the other, characterized in that said connecting device (60) comprises elastically deformable members (600) configured to allow relative movements between the inner and outer annular casings (24, 34), and in that each of the elastically deformable members (600) is chosen from a spring (644), a bar (624) and a pad (664).

2. Arrangement according to claim 1, characterized in that the connecting device (60) comprising the elastically deformable members (600), is made in one piece.

3. Arrangement according to claim 1, characterized in that the connecting device (60) is formed of several parts assembled together, at least one of the parts of which comprises the elastically deformable members.

4. Arrangement according to any one of claims 1 to 3, characterized in that the pads (664) are made of an elastically deformable material, or the springs (644) are embedded in an elastically deformable material, for example the elastically deformable material is of the elastomer or fluoroelastomer type. Tl 5. Arrangement according to any one of the preceding claims, characterized in that said connecting device (60) comprises two rings, respectively, internal (620) and external (622) connected to each other by bars (624) called connecting bars, the internal ring (620) being fixed to the internal annular casing (24), the external ring (622) being fixed to the external annular casing (34) and the connecting bars (624) forming said elastically deformable members (600).

6. Arrangement according to claim 5 and in combination with claim 2, characterized in that the inner and outer rings (620, 622) and the connecting bars (624) are formed in one piece.

7. Arrangement according to claim 5 or 6, characterized in that each of the connecting bars (624) is inclined tangentially relative to the internal annular casing (24), for example each of the connecting bars (624) extends at an angle of inclination (a) relative to the internal annular casing (24) which is between 10° and 45°, this angle being measured in a plane (P) tangent to the axis (X).

8. Arrangement according to any one of claims 5 to 7, characterized in that the connecting device (60) comprises a slot (626) at a connecting interface (625) between each of the connecting bars (624) and at least one of the inner and outer rings (620, 622).

9. Arrangement according to any one of claims 5 to 8, characterized in that each bar (624) has a thickness (E624) less than a thickness (E620, E622) of one of the internal and external rings (620, 622), these thicknesses (E620, E622, E624) being measured along the axis (X).

10. Arrangement according to claim 1 or 3, characterized in that said connecting device (60) consists of an annular row of springs (644), one of the two ends (644a, 644b) of the springs being fixed to one of the annular casings (24, 34) and the other of the two ends (664a, 664b) of the springs being supported on the other of the annular casings (24, 34).

11. Arrangement according to any one of claims 1 to 3, characterized in that said connecting device (60) comprises two rings, respectively, internal (620) and external (622) connected to each other by springs (644), in which the internal ring (620) is fixed to the internal annular casing (24), the external ring (622) is fixed to the external annular casing (34), and the springs (644) form said elastically deformable members (600).

12. Arrangement according to claim 10 or 11, characterized in that one of said annular casings (24, 34) or said inner and outer rings (620, 622) comprise fixing members (646) to the springs (644).

13. Arrangement according to claim 12, characterized in that each of the fixing members (646) to the springs (644) is a lug or a needle.

14. Arrangement according to any one of claims 1 to 3, characterized in that said connecting device (60) comprises an annular row of pads (664), in which each of the pads (664) comprises a first portion (664a) bearing on one of the annular casings (24, 34) and a second portion (664b) fixed to the other of the annular casings (24, 34), and the pads (664) forming said elastically deformable members (600).

15. Propulsion assembly (1) for an aircraft comprising a turbomachine (2) and a nacelle (3) surrounding at least part of the turbomachine (2), characterized in that it comprises a duct arrangement (6) according to any one of the preceding claims, the internal annular casing of this arrangement being formed by a casing of the turbomachine (2), and the casing external annular (34) of this arrangement being formed by a cover of the nacelle (3) or an ejection nozzle.

Images