COMBUSTION MODULE FOR A TURBOMACHINE

Abstract

A combustion module for a turbomachine is provided and includes an annular casing extending about a longitudinal axis; an annular combustion chamber located inside the casing and comprising coaxial annular walls connected to one another by an annular chamber dome, the walls and the chamber dome consisting of at least two annular envelopes, which are made of a ceramic-matrix composite material. The module can include anti-disengagement devices to keep the annular edges pressing axially against one another and fuel injectors borne by the casing and engaged in apertures of one of the envelopes.

Claims

1. A combustion module for a turbomachine of an aircraft, the combustion module comprising: an annular casing extending around a longitudinal axis; an annular combustion chamber located inside the casing and comprising coaxial annular walls, the walls being internal and external respectively, connected to each other by an annular bottom chamber, the walls and the bottom chamber being formed by at least two annular envelopes which are made of a ceramic matrix composite material and which comprise annular edges fitted together one inside the other and in axial abutment on each other; anti-disengagement devices configured to maintain the annular edges in axial abutment with each other, the devices being carried by the combustion chamber and/or the casing; and fuel injectors carried by the casing and engaged in orifices of one of the envelopes, the anti-disengagement devices having washers which are mounted around the injectors and tightened radially against the envelope, and which comprise lugs configured to cooperate by abutment and/or hooking with the other of the envelopes.

2. The combustion module according to claim 1, wherein the at least two annular envelopes comprise a first envelope defining the internal wall and the bottom chamber, and a second envelope defining the external wall, the annular edges being located at the junction of the external wall to the bottom chamber.

3. The combustion module as claimed in according to claim 2, wherein the annular edge of the first envelope comprises a scalloped shape.

4. The combustion module according to claim 2, wherein each of the washers is interposed between the second envelope and a nut for tightening the washer against the second envelope.

5. The combustion module according to claim 4, wherein the nut is screwed onto a barrel of a tubular socket mounted around the injector, wherein the socket comprises an annular abutment collar on a peripheral edge of the orifice in which the injector is engaged.

6. The combustion module according to claim 1, wherein each of the washers comprises two lugs oriented in substantially parallel directions.

7. The combustion module according to claim 2, wherein the lugs each have a shape complementary to that of the edge of the second envelope, and/or each have a hook shape for being engaged in an opening in the second envelope.

8. The combustion module according to claim 1, wherein each of the washers is made of stainless steel, for example of the A286 type.

9. The combustion module according to claim 1, wherein the combustion chamber is reverse flow.

10. A turbomachine for aircraft, comprising a combustion module according to claim 1.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0049] The invention will be better understood and other details, characteristics and advantages of the present invention will become clearer from the following description made by way of non-limiting example and with reference to the attached drawings, in which:

[0050] FIG. 1 is a schematic half-view in axial cross-section of a combustion module of a turbomachine comprising a return combustion chamber according to the prior art;

[0051] FIG. 2 is a partial schematic half view in axial cross-section of a first embodiment of a combustion module assembly according to the invention;

[0052] FIG. 3 is a schematic perspective view of the anti-disengagement device in FIG. 2;

[0053] FIG. 4 is a schematic cross-section along a plane C-C of FIG. 3;

[0054] FIG. 5 is a schematic cross-sectional view along a plane D-D of FIG. 3;

[0055] FIG. 6 is a schematic perspective view of an anti-disengagement device according to a second embodiment of the invention;

[0056] FIG. 7 is a partial schematic view in axial cross-section of an anti-disengagement device according to a third embodiment of the invention; and

[0057] FIG. 8 is a schematic half-view in axial cross-section of a fourth embodiment of an anti-disengagement device equipping a combustion module according to the invention.

DETAILED DESCRIPTION OF THE INVENTION

[0058] By convention, in the following description, the terms longitudinal and axial refer to the orientation of structural elements extending along the direction of a longitudinal axis, such as a longitudinal axis of a combustion module. The terms radial or vertical refer to an orientation of structural elements extending along a direction perpendicular to the longitudinal axis. The terms inner and outer, and internal and external are used in reference to a positioning with respect to the longitudinal axis. Thus, a structural element extending along the longitudinal axis comprises an inner face facing the longitudinal axis and an outer surface opposite its inner surface. The terms upstream and downstream are defined in relation to the orientation of circulation of the gases in a turbomachine.

[0059] FIG. 1 has been described above and illustrates a combustion module 1 of a turbomachine 10 according to the prior art.

[0060] FIGS. 2 to 8 show several embodiments of a combustion module 1 according to the invention.

[0061] In the following description, the invention applies generally to a turbomachine 10, in particular for aircraft, such as a turbojet or turboprop engine.

[0062] The turbomachine 10 typically comprises a compressor module comprising at least one compressor, a turbine module comprising at least one turbine and the combustion module 1 interposed between the compression and turbine modules.

[0063] As described above, the combustion module 1 comprises an annular casing 3 extending around a longitudinal axis X and surrounding an annular combustion chamber 2. This axis X may be coincident with a longitudinal axis, such as a rotational axis of a rotor, of the turbomachine 10. The chamber 2 and the casing 3 extend around the axis X. The chamber 2 may extend parallel or at an angle with respect to the axis X.

[0064] FIG. 2 shows schematically the chamber 2 comprising an internal annular wall 4 and an external annular wall 5. These walls 4, 5 are coaxial and connected by an annular bottom chamber 6. This chamber 2 is reverse flow. Thus, the bottom chamber 6 is arranged on the downstream side of the turbomachine and the chamber 2 opens out on the upstream side of the turbomachine towards the turbine module. Alternatively, when the chamber is direct, the bottom chamber 6 is arranged on the upstream side of the turbomachine. The bottom chamber 6 may comprise a transverse annular wall passing substantially through a first plane P1 which is perpendicular to the axis X.

[0065] The external wall 5 is attached to the casing 3 which carries an annular row of fuel injectors 7 angularly distributed around the axis X so as to supply the chamber 2 with fuel. In particular, the external wall 5 comprises an annular row of orifices 54 extending around the axis X. Each of the orifices 54 has an internal diameter D.sub.54. Each of the orifices 54 comprises a peripheral edge 56. Each of the orifices 54 is suitable for receiving a fuel injector 7. In the example shown in FIG. 2, the injector 7 passes through an axis A which is substantially perpendicular to the axis X. Alternatively, the orifices 54 and the injectors 7 could be inclined or parallel to the axis X.

[0066] In the frame of the invention, the chamber 2 is made of a CMC ceramic matrix composite material. The internal and external walls 4, 5 and the bottom chamber 6 are formed by at least two annular envelopes 50, 60 made of a ceramic matrix composite material CMC.

[0067] In the example shown in FIG. 2, the internal annular wall 4 and the bottom chamber 6 are formed in one single piece by a first envelope 60. In the example, the first envelope 60 has a general inverted S shape, in which one of the two loops corresponds substantially to the bottom chamber and the other of the loops corresponds substantially to the internal wall 4 and the internal bend 4a of the chamber. The external annular wall 5 is formed in one single piece by a second envelope 50. In the example, the second envelope 50 has a general C shape, in which an upper portion substantially corresponds to the external wall 5 and a lower portion substantially corresponds to the external bend 5a.

[0068] In the example, the first and second envelopes 50, 60 are connected to each other on the downstream side. These envelopes 50, 60 continue on the upstream side with a turnaround 4a, 5a which extends radially towards the interior (with respect to the axis X) of the module 1, to open out into a dispenser 94 of the turbine module.

[0069] The first and second envelopes 50, 60 each comprise, respectively, an annular edge 62 referred to as internal, and an annular edge 52 referred to as external. The annular edges 52, 62 are fitted together one inside the other, in particular at the level of the connection between the external wall 5 and the bottom chamber 6. In particular, the internal edge 62 rests radially (or substantially radially) on the external edge 52. Radial abutment means an abutment force exerted by the internal edge 62 in a transverse plane (with respect to the axis X) on a cylindrical surface of the external edge 52. By substantially radial abutment is meant an abutment force exerted by the internal edge 62 along a plane inclined (with respect to the axis X) on a frustoconical surface of the external edge 52, in particular when the chamber 2 is inclined with respect to the axis X.

[0070] Furthermore, the edge 62 of the first envelope 60 (corresponding to the bottom chamber 6 in the example) may comprise a scalloped shape (not shown in the figures), in particular near the injectors 7. This allows in particular the chamber 2 to be compacted axially. The scalloped shape can be made by a sequence of projecting or re-entrant arc segments, such as undulations.

[0071] One of the particularities of the invention is that the combustion module 1 comprises anti-disengagement devices 8 carried by the chamber 2 (shown in FIG. 2 to 7) or carried by the casing 3 of the module 1 (shown in FIG. 8). Each of the devices 8 is used to maintain the annular edges 52, 62 in axial (or substantially axial) abutment with each other, or with a limited clearance. In this way, the envelopes 50, 60 of the chamber 2 are prevented from becoming disassociated during operation and at a standstill (and thus from being connected to the external wall 5 and the bottom chamber 6), while allowing a simple and efficient assembly and disassembly of the devices 8 within the available overall dimension of the combustion module 1.

[0072] Axial abutment means an abutment force or a contact exerted by the external edge 52 along the axis X on a cylindrical surface of the internal edge 62. By substantially axial abutment is meant an abutment force or a contact exerted by the external edge 52 along a plane inclined (with respect to the axis X) on a frustoconical surface of the internal edge 62, in particular when the chamber 2 is inclined with respect to the axis X; or conversely, an abutment force exerted by the internal edge 62 along a plane inclined (with respect to the axis X) on a frustoconical surface of the external edge 52.

[0073] According to a first embodiment of the invention, illustrated in FIGS. 2 to 5, the anti-disengagement devices 8 can be installed on the chamber 2. In particular, in these example figures, the devices 8 are mounted around the fuel injectors 7.

[0074] The devices 8 are each formed with a washer 86 which is configured to be fitted around the injector 7.

[0075] With reference to FIG. 3, the washer 86 therefore has a generally annular and flat shape. This washer 86 comprises a first central opening 860 and lugs 862. The opening 860 has an internal diameter D.sub.860.

[0076] The washer 86 may comprise one or more lugs 862. The number and the dimensions (shape, length, thickness, etc.) of the lugs 862 per washer 86 may vary depending on the dimensions and materials of the parts making up the combustion module 1. In the example shown in FIG. 3, the washer 86 comprises two lugs 862 which are oriented parallel to each other. These lugs 862 each have a hook shape.

[0077] The thickness of each washer 86 can determine their degree to which they help to maintain tightening forces, particularly during the flight phases of the turbomachine.

[0078] The washer 86 may be made of a CMC-type composite material or a metal alloy. Preferably, the washer 86 is made of stainless steel, for example of the A286 type. The advantages of stainless steel A286 are that it is compatible with the thermal environment of the combustion chamber 2, and has a high coefficient of thermal expansion to optimally maintain the connections between parts at extreme operating temperatures of the combustion module 1.

[0079] The washer 86 is configured to be tightened radially (i.e. substantially perpendicular to the axis X) against the second envelope 50 of the external wall 5 by a tightening nut 84 and a socket 82.

[0080] With reference to FIG. 5, the socket 82 has a tubular shape and therefore comprises a second central opening 820 and a barrel 822. The second opening 820 has an internal diameter D.sub.820. The barrel 822 may comprise an external thread.

[0081] The socket 82 also comprises an annular collar 824. The collar 824 and the barrel 822 may be delimited by a tubular portion 826. In the example shown in FIG. 5, the annular collar 824 comprises a first flank 824a which has a flat shape and a second flank 824b which has a frustoconical shape. The second flank 824b tapers towards the tubular portion 826.

[0082] In hot operation, the frustoconical shape of the second flank 824b of the annular collar 824 of the socket 82 may expand. This may result in a displacement relative to the envelope 50. This frustoconical shape of the second flank 824b may return a radial displacement relative to an axial displacement, leading to a tightening of the connection between the socket 82, the nut 84 and the envelope 50. The washer 86 may be made of a material having a coefficient of thermal expansion allowing to compensate for an expansion gap between the envelope 50 and the nut 84.

[0083] Furthermore, in the example shown in FIG. 5, the collar 824 has an external diameter D.sub.824 which is greater than the external diameters D.sub.826, D.sub.822 of the tubular portion 826 and the barrel 822. The external diameter D.sub.826 of the tubular portion 826 is greater than the external diameter D.sub.822 of the barrel 822.

[0084] The assembly of the washer 86 of the first embodiment on the chamber 2, in particular around the injectors 7 and on the edges 52, 62 of the envelopes 50, 60, is now described with reference to FIGS. 3 to 5.

[0085] For this purpose, the socket 82 is mounted around the injector 7, in particular through the second opening 820. This second opening 820 thus extends around the axis A of the injector 7. In the example shown in FIG. 5, the internal diameter D.sub.820 of the second opening 820 of the socket is therefore substantially similar to the external diameter D7 of the injector 7.

[0086] Next, the annular edge 52 of the second envelope 50 comprises the orifices 54 into which the injectors 7 are intended to be engaged. The edge 52 is mounted around the collar 824 of the socket 82, in particular through the orifices 54. This allows the peripheral edge 56 of the orifice 54 to be in abutment on the second flank 824b of the collar 824. In the example shown in FIG. 5, the peripheral edge 56 is in abutment on the second flank 824b along an inclined position with respect to the axis X and A. Furthermore, the external diameter D.sub.826 of the tubular portion 826 of the socket 82 is substantially similar to the internal diameter D.sub.54 of the orifice 54 of the second envelope 50.

[0087] The washer 86 is then mounted around the socket 82, in particular through the first opening 860. This first opening 860 also extends around the axis A. In the example shown in FIG. 5, the internal diameter D.sub.860 of the first opening 860 of the washer is therefore substantially similar to the external diameter D.sub.826 of the tubular portion 826 of the socket and the internal diameter D64 of the orifice 54 of the second envelope 50. Furthermore, the annular edge 62 of the first envelope 60 comprises in the example openings 64 of complementary shape to the lugs 862 of the washer 86. This allows the hook-shaped lugs 862 to engage into the openings 64 of the first envelope 60, as shown in FIG. 4.

[0088] Finally, the nut 84 is screwed around the barrel 822 of the socket 82, in particular through a third opening 840 of the nut 84. This allows to ensure that the washer 86 and the edge 52 of the second envelope 50 are maintained on the socket 82. In the example shown in FIG. 5, the third opening 840 has an internal diameter D840 substantially similar to the external diameter D.sub.822 of the barrel 822 of the socket 82. This third opening 840 may comprise an internal thread complementary to the external thread of the barrel 822 of the socket 82.

[0089] FIG. 6 illustrates one of the anti-disengagement devices 8 and its assembly according to a second embodiment, in which the anti-disengagement devices 8 can also be installed on the chamber 2.

[0090] The anti-disengagement devices 8 of the second embodiment are distinguished from the devices 8 of the first embodiment by the lugs 862 of the washer 86 and the edge 62 of the first envelope 60.

[0091] With reference to FIG. 6, the lugs 862 of the washer 86 have an elongated and curved shape. The edge 62 of the first envelope 60 comprises a boss 66 passing substantially through a second plane P2. This plane P2 is substantially perpendicular to the axis X of the module 1 and located upstream of the first plane P1 of the bottom chamber 6. Alternatively, the edge 62 may comprise an allowance of the envelope 60 at the level of the plane P2.

[0092] In FIG. 6, the lugs 862 and the boss 66 have a complementary shape. This allows the lugs 862 to attach to the boss 66 by direct abutment, so that the lugs 862 tightened radially against the edge 52 abut the boss 66 of the edge 62. This configuration therefore also allows the edges 52, 62 of the envelopes 50, 60 to be maintained axially against each other.

[0093] Preferably, the lugs 862 are elongated so that their free and curved ends face the plane P1 corresponding substantially to the transverse wall of the bottom chamber 6. In particular, this allows to compensate for axial displacement of the assembly of the edges 52, 62 during operation of the combustion module 1.

[0094] In addition, the elongated shape of the lugs 862 allows for flexibility in the connection between the lugs 862 and the boss 66. In this way, the assembly between the envelopes 50, 60 (of the walls 5, 6 and of the bottom chamber 6), is rigid in particular with permanent contact between the lugs 862 and the boss 66, and with little or no assembly clearance between the edges 52, 62 of the envelopes 50, 60.

[0095] This second embodiment has in particular the advantage of avoiding complex machining on the edge 62 of the first envelope 60.

[0096] FIG. 7 illustrates one of the anti-disengagement devices 8 and its assembly according to a third embodiment, in which these devices 8 can also be installed on the chamber 2.

[0097] The anti-disengagement devices 8 of the third embodiment are distinguished from the devices 8 of the first embodiment by the lugs 862 of the washer 86 and the edge 62 of the first envelope 60.

[0098] With reference to FIG. 7, the edge 62 of the first envelope 60 comprises at least one shoulder 68, so as to form an axial abutment surface for one of the lugs 862 of the washer 86. Preferably, the shoulder 68 is made on an allowance of the envelope 60 located substantially at the level of the plane P2. The lugs 862 and the shoulders 68 may have a complementary shape.

[0099] In FIG. 7, the lug 862 comprises a curved free end 864 engaging in the shoulder 68 of the edge 62. In this way, the lugs 862 are also attached in the shoulders 68 by direct axial abutment. Thus, this configuration also allows the edges 52, 62 to be maintained together.

[0100] This third embodiment is a simple alternative solution to carry out and to implement in order to prevent the connection of the envelopes 50, 60 from becoming disassociated.

[0101] According to a fourth embodiment of the invention, illustrated in FIG. 8, the anti-disengagement devices 8 may be carried by the casing 3. In particular, in this example in FIG. 8, the devices 8 and the casing 3 are monoblocs (i.e. from one material).

[0102] Advantageously, these devices 8 are abutment members projectably formed on the casing 3. These abutment members may comprise free ends 880 adapted to abut the chamber 2, in particular the bottom chamber 6. This configuration allows to prevent the bottom chamber 6 from any displacement relative to the external wall 5.

[0103] These abutment members can be made of a rigid or flexible material. For example, the abutment members are made of a composite, metal, or metal alloy material.

[0104] Preferably, the abutment members can be made of the same material as the casing 3 but with a first thickness reduced compared to a second thickness of the casing 3. In particular, this allows the abutment members to be flexible, while still being able to exert a sufficient pressure on the chamber 2 to maintain the edges 52, 62 in axial abutment on each other.

[0105] In the case of abutment members made of flexible material, the free ends 880 may come into direct contact with the bottom chamber 6. In the case of abutment members made of rigid or flexible material, a mounting clearance and/or a clearance to compensate for expansion during operation can be added between the abutment members and the bottom chamber. These mounting and expansion clearances may vary depending on the materials or dimensions (such as thickness) used for the envelopes and the abutment members. As an example, this mounting clearance and/or expansion compensation clearance is in the order of a millimetre.

[0106] The abutment members and the casing 3 can be made monobloc (i.e. from one material).

[0107] In FIG. 8, the abutment members are in the form of arms 88. The arm 88 has an elongated shape in the direction of the bottom chamber 6. The end 880 of the arm 88 may be inclined with respect to the axis X. This end 880 comprises an abutment surface 882 on the bottom chamber 6. In the example shown in FIG. 8, the abutment surface 882 passes substantially through the first plane P1.

[0108] The casing 3 may comprise between three and eight arms 88 distributed circumferentially around the axis X, so that an air flow from a diffuser 92 of the compressor module may circulate into the module 1.

[0109] In addition, the free ends 880 of the arms 88 may comprise a thermal protection coating. This allows in particular the temperature of the arms 88 to be lowered. This coating can be combined with a different material from the material used for making the abutment members. This allows for a chemical or thermal compatibility between the abutment members and the chamber.

[0110] This fourth embodiment of the devices 8 has the particular advantage of favouring the hyperstatism (i.e. making immovable) of the edges 52, 62 fitted together, and thus limiting the movements and/or deformations.

[0111] According to another embodiment (not shown in the figures), the abutment members of the fourth embodiment of FIG. 8 can be combined with the washers of at least one of the embodiments of FIGS. 2 to 7. Indeed, the devices 8 can be formed by both washers 86 and abutment members.

[0112] The anti-disengagement devices equipping the combustion module of the present invention are advantageous in particular for the following reasons: [0113] they strengthen the assembly between the parts made of composite material of the CMC type in a combustion module, [0114] they eliminate the disassociation of assembled parts in the combustion module during operation, [0115] they propose a removable assembly and disassembly of the anti-disengagement device on the chamber, [0116] they propose an alternative to the use of bolt type attachment, [0117] they limit the maintenance cost of the combustion chamber, and [0118] they are easily adapted to the existing turbomachines.

[0119] In general, the proposed solutions are simple, effective and economical to carry out and assemble on a turbomachine and an aircraft, while ensuring the safe assembly and disassembly of the combustion chamber (made of composite material parts) in a turbomachine.