Recovered-cycle aircraft turbine engine
Patent Information
- Authority / Receiving Office
- EP · EP
- Patent Type
- Applications
- Current Assignee / Owner
- Filing Date
- 2024-05-27
- Publication Date
- 2026-04-08
AI Technical Summary
Integrating a recovered cycle into an aircraft turbomachine with a centrifugal compressor is complex, particularly in minimizing pressure losses and ensuring homogeneous air supply to the heat exchanger and combustion chamber while being non-intrusive to existing components.
The use of multiple sectorized volutes distributed around the axis, replacing traditional single volutes, to collect compressed air from the centrifugal compressor and supply heated air to the combustion chamber, minimizing pressure losses and ensuring optimal operation by providing residual gyration.
This configuration allows for efficient air circulation in the heat exchanger, minimizes radial bulk, and ensures proper combustion chamber operation with reduced pressure losses and aerodynamic stresses, enhancing the turbomachine's performance and thermal efficiency.
Smart Images
Figure FR2024050676_05122024_PF_FP_ABST
Abstract
Description
[0001] DESCRIPTION
[0002] TITLE: RECOVERED CYCLE AIRCRAFT TURBOMACHINE
[0003] Technical field of the invention
[0004] The present invention relates to an aircraft turbomachine equipped with scrolls for implementing a recovered cycle.
[0005] Technical background
[0006] The technical background includes in particular documents GB-A-615 680 and GB-A-817 951.
[0007] An aircraft turbomachine comprises a gas generator comprising, from upstream to downstream, in the direction of gas flow, at least one compressor, an annular combustion chamber, and at least one turbine. The compressor is supplied with air and compresses it. The compressed air is mixed with fuel and burned in the combustion chamber, which supplies combustion gases to the turbine. These combustion gases expand in the turbine and rotate its rotor, which in turn drives the compressor rotor via a common shaft.
[0008] A turbomachine can be equipped with one or more bodies each comprising a compressor rotor connected by a shaft to a turbine rotor.
[0009] It is thus understood that a turbomachine can comprise several successive compressors (for example a low pressure compressor followed by a high pressure compressor), as well as several successive turbines (for example a high pressure turbine followed by a low pressure turbine).
[0010] In this application, a conventional cycle turbomachine is understood to mean a turbomachine in which the compressed air leaving the compressor(s) directly feeds the combustion chamber.
[0011] Conversely, a recuperative cycle turbomachine is a turbomachine in which the combustion gases flowing out of the turbine(s) are used to heat the compressed air leaving the compressor(s) and intended to supply the combustion chamber. This technology improves the performance of the turbomachine because the quantity of fuel required to reach the operating temperature of the turbomachine is less than that required in a conventional cycle turbomachine.
[0012] Figure 1 very schematically represents a recovered cycle turbomachine.
[0013] The turbomachine 1 comprises from upstream to downstream a compressor 2, an annular combustion chamber 3, and a turbine 4. The rotors of the compressor 3 and the turbine 4 are connected together by a shaft 6 and form a single body.
[0014] The turbomachine 1 comprises a heat exchanger 7, a first circuit of which is supplied by combustion gases taken from the outlet of the turbine 4. The exchanger 7 comprises a second circuit which is supplied with compressed air leaving the compressor 2 and which provides heated compressed air to the combustion chamber 3.
[0015] The integration of this technology can be complicated when the compressor 2 is of the centrifugal type. A centrifugal compressor is a compressor that has an inlet oriented parallel to the longitudinal axis of the turbomachine, and an outlet that is oriented radially relative to this axis.
[0016] This type of compressor is associated with a system for diffusing and straightening the compressed air flow. This system comprises a diffuser-straightener assembly and therefore comprises an annular diffuser which is oriented substantially radially and which is aligned with the outlet of the centrifugal compressor, and an annular straightener which is oriented substantially axially to direct the compressed air flow towards the combustion chamber.
[0017] Integration solutions for this technology have already been proposed in the past and consist of using a set of two volutes (W0-A1 -2021 / 255383 and W0-A1 -2021 / 255384).
[0018] A volute is a duct wound in a spiral around an axis and whose fluid passage section changes. In the context of the present application, a volute comprises an annular duct wound around the longitudinal axis of the turbomachine and connected to a first port located at the outer periphery of the duct and oriented in the tangential direction, and a second port located at the inner periphery of the duct and oriented in the radial direction. A first volute has its second port which is connected to the outlet of the diffuser and its first port which feeds the inlet of the second circuit of the exchanger. The outlet of this second circuit is connected to the first port of the second volute, the second port of which is connected to the inlet of the rectifier.
[0019] The present invention proposes an improvement to this technology, which makes it possible to solve all or part of the following technical problems:
[0020] - ensure the collection of air at the outlet of the centrifugal compressor while minimizing pressure losses,
[0021] - feed the heat exchanger evenly,
[0022] - supply the combustion chamber with air from the heat exchanger while minimizing pressure losses and preferably with residual gyration to ensure optimal operation of the chamber, and
[0023] - implement a gas flow bypass (taken from the compressor outlet and re-injected into the combustion chamber) while being as non-intrusive as possible on the components of the turbomachine which is not originally designed for this operating mode.
[0024] Summary of the invention
[0025] The invention relates to an aircraft turbomachine, comprising:
[0026] - a centrifugal compressor extending around an axis, also called a longitudinal axis,
[0027] - an annular combustion chamber extending around the axis,
[0028] - a heat exchanger comprising a first circuit supplied with exhaust gas from the turbomachine, and a second circuit comprising at least one inlet connected by a first annular system to at least one outlet of the centrifugal compressor, and at least one outlet connected by a second annular system to at least one inlet of the annular combustion chamber, the first and second systems extending around the axis, characterized in that each of the first and second systems is sectorized and comprises at least two volutes forming system sectors and distributed around said axis, each of the volutes comprising at one circumferential end a first port and at an opposite circumferential end a second port, and having an evolving passage section which is maximum at the first port and minimum at the second port,the scrolls of the first system having their second ports which are inlet ports and which are connected to said at least one outlet of the centrifugal compressor, and their first ports which are outlet ports and which are connected to said at least one inlet of the second circuit, and the scrolls of the second system having their first ports which are inlet ports and which are connected to said at least one outlet of the second circuit, and their second ports which are outlet ports and which are connected to said at least one inlet of the annular combustion chamber.,
[0029] The volute used in the prior art to take compressed air from the diffuser outlet is therefore replaced by a system with several volutes distributed around the axis. In the same way, the volute used in the prior art to inject air at the inlet of the chamber is replaced by a system with several volutes distributed around the axis. It is therefore understood that each volute of the prior art is replaced by two or more volutes. It is also understood that the volutes form sectors and therefore that their angular extent around the axis is less than 360° and depends on the number of volutes in the system. For a system with two sectors and therefore two volutes, each volute (also called a half-volute) has an angular extent of at least 180°. For a system with three sectors and three volutes, each volute has an angular extent of at least 120°. For a system with four sectors and four volutes, each volute has an angular extent of at least 90°.The volutes of the same system may have their circumferential ends overlapping each other in the axial direction.
[0030] The presence of two or more volutes instead of a single 360° volute makes it possible to limit their diameter and therefore the radial size of the system and the turbomachine. It also makes it possible to supply the heat exchanger in two or more zones distributed around the axis, which ensures a homogeneous distribution of the "cold" air flow in the exchanger to maximize its thermal efficiency.
[0031] The turbomachine according to the invention may comprise one or more of the following steps or characteristics, considered independently of one another or in combination with one another: - each of the first and second systems comprises two volutes which each extend over at least 180° around the axis;
[0032] - each of the first and second systems comprises three or four volutes;
[0033] - the first ports of the volutes of the first system are diametrically opposite with respect to the axis, and their second ports are diametrically opposite with respect to the axis;
[0034] - the first ports of the volutes of the second system are diametrically opposed relative to the axis, and their second ports are diametrically opposed relative to the axis;
[0035] - the first ports of the volutes of the first system are axially aligned with the first ports of the volutes of the second system, and the second ports of the volutes of the first system are axially aligned with the second ports (44) of the volutes of the second system;
[0036] - the (longitudinal) axis is an axis of symmetry for the volutes of the first system, on the one hand, and for the volutes of the second system, on the other hand;
[0037] - the second ports of the volutes of the first and second systems are oriented in the radial direction, and the first ports of the volutes of the first and second systems are oriented in the tangential direction;
[0038] - the second ports of the volutes of the first and second systems are connected to ends of bent conduits, these bent conduits having opposite ends oriented parallel to the axis;
[0039] - the outlets of the elbow conduits are each connected to a flexible bellows;
[0040] - the first and second systems are axially attached to each other;
[0041] - the second ports of the second system comprise airflow straightener vanes; the presence of the straightener vanes integrated into the volutes makes it possible to ensure the presence of a residual gyration at the inlet of the chamber in accordance with the need; these straightener vanes can replace the straightener of the prior art provided upstream of the chamber for example. The present invention also relates to a set of volutes for a turbomachine as described above, this set comprising first and second annular systems which extend around the same axis and which each comprise at least two volutes which form system sectors and which are distributed around the axis, each of the volutes comprising at one circumferential end a first port and at an opposite circumferential end a second port, and having an evolving passage section which is maximum at the first port and minimum at the second port.
[0042] Brief description of the figures
[0043] Other characteristics and advantages of the invention will appear during the reading of the detailed description which follows for the understanding of which reference will be made to the appended drawings in which:
[0044] [Fig.1] Figure 1 is a very schematic view of a recovered cycle aircraft turbomachine;
[0045] [Fig.2] Figure 2 is a partial schematic axial sectional view of a recovered cycle aircraft turbomachine,
[0046] [Fig. 3] Figure 3 is a schematic perspective view of a set of volutes according to the invention;
[0047] [Fig. 4] Figure 4 is a schematic axial sectional view of the volute assembly of Figure 3;
[0048] [Fig.5] Figure 5 is a schematic perspective view of the volute assembly of Figure 3 and a heat exchanger;
[0049] [Fig. 6] Fig. 6 is another schematic perspective view of the volute assembly and heat exchanger of Fig. 5;
[0050] [Fig.7] Figure 7 is a schematic perspective view of the heat exchanger of Figure 5; and
[0051] [Fig.8] Figure 8 is a schematic perspective view of a two-volute annular system.
[0052] Detailed description of the invention
[0053] Figure 1 has already been described in the above.
[0054] Figure 2 illustrates a part of an aircraft turbomachine 10 according to the invention.
[0055] The turbomachine 10 is partially shown in Figure 1 and conventionally comprises at least one compressor, an annular combustion chamber and at least one turbine. In the example shown, the turbomachine 10 comprises two successive compressors 12, 14 which are therefore mounted one after the other and which are both of the centrifugal type.
[0056] The compressors 12, 14 have an annular shape and are coaxial and centered on an axis A also called the longitudinal axis, which is the longitudinal axis of the turbomachine 10. Each compressor 12, 14 comprises a stator 16 and a bladed rotor 18, called a wheel, which rotates inside the stator 16 and around the axis A.
[0057] Each compressor 12, 14 comprises an inlet 20 oriented axially upstream and an outlet 22 oriented radially outwards with respect to the axis A. The expressions upstream and downstream here refer to the general flow of air and gases in the turbomachine 10.
[0058] Compressor 14 is thus located downstream of compressor 12.
[0059] The turbomachine 10 of FIG. 2 further comprises a combustion chamber 24 which is located downstream of the compressor 14.
[0060] The combustion chamber 24 comprises two annular walls, respectively internal 24a, and external 24b, which define between them an annular cavity into which compressed air from the compressor 14 and fuel from injectors 26 are injected and mixed.
[0061] The walls 24a, 24b are connected to each other by a chamber bottom 28 which has an annular shape and which comprises orifices (not visible) for the passage of compressed air coming from the compressor 14 for supplying the chamber 24.
[0062] The combustion chamber 24 is surrounded by an external annular casing 29 which carries in particular the injectors 26.
[0063] In the example shown, the chamber 24 is of the inverted type because its chamber bottom 28 is located on the downstream side of this chamber. The outlet of the chamber 24 is located on the upstream side of the chamber and is connected to one or more turbines 30 arranged downstream of the chamber.
[0064] The combustion gases injected into the turbine 30 expand and drive its rotor which is connected by a shaft to the rotor 18 of at least one of the compressors 12, 14 for the purpose of driving them in rotation around the axis A.
[0065] The combustion gases are then discharged into a combustion gas exhaust nozzle which is not shown. In a conventional cycle turbomachine 10, the connection of the compressor outlet 14 to the combustion chamber 24 is achieved by an air diffusion and rectification system 32, also called a diffuser-rectifier.
[0066] This system 32 includes:
[0067] - an annular diffuser 34 which is oriented substantially radially and which comprises at its internal periphery an inlet 34a supplied by the compressor 14 and aligned radially with the outlet 22 of the latter, and an outlet 34b at its external periphery which opens radially towards the outside; and
[0068] - an annular rectifier 36 which is oriented substantially axially in the example shown and which comprises at its upstream end an inlet 36a, and at its downstream end an outlet 36b to supply the combustion chamber 24.
[0069] The diffuser 34 is located upstream of the chamber 24 and its walls 24a, 24b and the rectifier 36 extends around the chamber 24 and its walls 24a, 24b and inside the casing 29. The diffuser 34 can be fixed by clamping to the stator 16 of the compressor 12 and / or the compressor 14. The rectifier 36 can be fixed by clamping to the casing 29.
[0070] The diffuser 34 and the rectifier 36 may be vaned.
[0071] In a conventional cycle turbomachine 10, the outlet 34b of the diffuser 34 is directly connected, for example by an L-shaped duct to the inlet 36a of the rectifier 36. Otherwise, the compressed air leaving the compressor 14 directly feeds the combustion chamber 24.
[0072] According to the invention, the turbomachine 10 is of the recovered cycle type, which means that the compressed air leaving the compressor 14 is heated before being injected into the combustion chamber 24.
[0073] The heating of the compressed air is carried out by means of a heat exchanger 38 on the one hand and a set of volutes 40 on the other hand.
[0074] The heat exchanger 38 is schematically represented and essentially comprises two circuits 38a, 38b, namely:
[0075] - a first circuit 38a, one inlet 38aa of which is connected to means for sampling exhaust gases at the outlet of the turbines 30 or in the aforementioned exhaust nozzle, and an outlet 38ab which can also be connected to the exhaust nozzle for the purpose of releasing these gases into the atmosphere, and - a second circuit 38b comprising at least one inlet 38ba and at least one outlet 38bc connected to the set of volutes 40.
[0076] The volute assembly 40 is best seen in Figures 3 through 8.
[0077] The assembly 40 comprises two annular systems 40a, 40b which extend around the same axis, namely the longitudinal axis A of the turbomachine 10, and which can be joined together as in the example shown.
[0078] Each system 40a, 40b is sectorized and comprises at least two volutes 40a1, 40a2, 40b1, 40b2 forming sectors of this system and distributed around the axis A.
[0079] The volute assembly 40 is connected to the diffuser 34, to the rectifier 36 or to the combustion chamber 24, and to the exchanger 38 in the following manner. The system 40a is connected to the outlet 34b of the diffuser 34 and feeds the inlet 38ba of the second circuit 38b of the exchanger 38. The outlet 38bb of this second circuit 38b is connected by the second system to the inlet 36a of the rectifier 36 or directly to the combustion chamber 24 as will be seen in the following.
[0080] In the example shown, the system 40a comprises two volutes 40a1, 40a2 which form two sectors of the first system 40a. The volute 40a1 extends from 0 to at least 180° around the axis A, and the volute 40a2 extends from 180 to at least 360° around the axis A. The volutes 40a1, 40a2 are therefore generally diametrically opposed even if they have particular configurations which will be described in the following. The volutes 40a1, 40a2 have reversed winding directions. The circumferential ends of the volutes 40a1, 40a2 may overlap each other in the axial direction, as can be seen in the drawings.
[0081] The first system 40a makes it possible to connect the input 38ba or the inputs 38ba of the first circuit 38b to one or more outputs 34b of the diffuser 34.
[0082] Each volute 40a1, 40a2 has a first port 42, which is an outlet port, and a second port 44, which is an inlet port, and each volute 40a1, 40a2 has an evolving passage section which is maximum at the first port 42 and minimum at the second port 44.
[0083] Each volute 40a1, 40a2 has its second port 44 (inlet port) which is connected to the outlet 34b or to one of the outlets 34b and its first port 42 (outlet port) which is connected to the inlet 38ba or to one of the inlets 38ba of the second circuit 38b. Insofar as the system 40a comprises two volutes 40a1, 40a2 and therefore two outlet ports (first ports 42), these outlet ports can be connected to the same inlet 38ba of the exchanger 38 or to two separate inlets 38ba of the exchanger 38.
[0084] In the figures, it is further noted that the second ports 44 (inlet ports) of the volutes 40a1, 40a2 are diametrically opposed with respect to the axis A, and their first ports (42 (outlet ports) are also diametrically opposed with respect to the axis A.
[0085] Axis A can be an axis of symmetry for volutes 40a1, 40a2.
[0086] In the example shown, the second ports 44 (inlet port) of the volutes 40a1, 40a2 are oriented in the radial direction, and their first ports 42 (outlet ports) are oriented in the tangential direction. These first ports 42 can be connected to ends or inlets of bent conduits 50, these bent conduits 50 having ends or outlets oriented parallel to the axis A.
[0087] The outlets of the conduits 50 are each connected to a flexible bellows 60 for example.
[0088] The system 40b comprises two volutes 40b1, 40b2 which form two sectors of the second system 40b. The volute 40b1 extends from 0 to at least 180° around the axis A, and the volute 40b2 extends from 180 to at least 360° around the axis A. The volutes 40b1, 40b2 are therefore generally diametrically opposed even if they have particular configurations which will be described in the following. The volutes 40b1, 40b2 have reversed winding directions. The circumferential ends of the volutes 40b1, 40b2 may overlap each other in the axial direction, as can be seen in the drawings.
[0089] The second system 40b makes it possible to connect the output 38bb or the outputs 38bb of the first circuit 38b to the inlet of the combustion chamber 24.
[0090] Each volute 40b1, 40b2 has a first port 46, which is an inlet port, and a second port 48, which is an outlet port, and each volute 40b1, 40b2 has an evolving passage section which is maximum at the first port 46 and minimum at the second port 48.
[0091] Each volute 40b1, 40b2 has its second port 48 (output port) which is connected to the input 36a or to one of the inputs 36a and its first port 46 (input port) which is connected to the output 38bb or to one of the outputs 38bb of the second circuit 38b. To the extent that the system 40b comprises two volutes 40b1, 40b2 and therefore two inlet ports (first ports 46), these inlet ports can be connected to the same outlet 38bb of the exchanger 38 or to two separate outlets 38bb of the exchanger 38. In the figures, it can also be seen that the second ports 48 (outlet ports) of the volutes 40b1, 40b2 are diametrically opposite relative to the axis A, and their first ports (46 (inlet ports) are also diametrically opposite relative to the axis A.
[0092] Axis A can be an axis of symmetry for volutes 40b1, 40b2.
[0093] In the example shown, the second ports 48 (outlet ports) of the volutes 40b1, 40a2 are oriented in the radial direction, and their first ports 46 (inlet ports) are oriented in the tangential direction. These first ports 46 can be connected to ends or outlets of bent conduits 80, these bent conduits 80 having ends or inlets oriented parallel to the axis A.
[0094] The outlets of the conduits 80 are each connected to a flexible bellows 60 for example.
[0095] Advantageously, the second ports 48 (outlet port) of the volutes 40b1, 40b2 comprise air flow rectifier vanes 70 (see FIG. 4). These rectifier vanes 70 have the function of driving the air flow into rotation at the inlet of the chamber 24. Due to this gyration imposed on the air flow, the rectifier vanes 70 could replace the rectifier 36 generally provided upstream of the chamber and shown in FIG. 2. In this case, it could be considered that the second ports 48 (outlet port) are directly connected to the combustion chamber 24.
[0096] The volutes 40a, 40b each have a passage section of circular or oval shape, preferably over their entire circumferential extent. By oval shape is meant any elliptical or ovoid shape, or even oblong. Other shapes are however conceivable.
[0097] The volutes 40a, 40b are joined together and, preferably, are not nested within each other so as to limit the heat exchanges between the air flows circulating simultaneously in the two volutes. This means that the passage section of one volute does not encroach on the passage section of the other volute.
[0098] Furthermore, the systems 40a, 40b can be fixed to the casing by clamping. In the example shown, the volute assembly 40 is formed from a single piece with an annular flange 90 for fixing to the casing 29 (see FIG. 4).
[0099] The systems 40a, 40b and the volutes 40aa, 40a2, 40b1, 40b2 are therefore formed from a single piece.
[0100] The set of volutes 40 can be manufactured in different ways. The volutes can be manufactured in two parts for example: one part in casting and one part via a sheet metal assembly. One variant would be to manufacture the volutes in three parts welded / screwed together: one part in casting, one part by additive manufacturing, and one part in sheet metal. Another variant would be to make the four half-volutes entirely in casting.
[0101] Another variant would consist of defining a system of volutes, ducts and exchanger that is completely modular with the possibility of quickly dismantling the exchanger once the turbomachine is integrated into the aircraft depending on the user's needs or if there is a need to carry out tests of the turbomachine without exchanger for example.
[0102] The present invention has several advantages including:
[0103] - the collection and supply volutes allow the air flow to circulate evenly in the exchanger while ensuring minimal pressure losses;
[0104] - the rectifier vanes located downstream of the chamber supply volutes direct the air flow with the appropriate rotation value to ensure the proper functioning of the combustion chamber;
[0105] - the half-volutes make it possible to minimize the diameter of the ducts bringing the air to the exchanger compared to a complete 360° volute and therefore to limit the radial size of the turbomachine;
[0106] - the half-volutes allow, compared to a complete volute over 360°, to ensure the balance of the rotor of the centrifugal compressor by limiting the aerodynamic stresses (static pressure peaks), and to ensure better homogeneity of the thermomechanical stress of the volute. The present invention can be used and / or applied for turbomachines operating with a recovered cycle (presence of a heat exchanger). This includes:
[0107] - turboshaft engines for helicopters or drones,
[0108] - turboprop engines for aircraft or drones,
[0109] - turbofans for civil or military aircraft,
[0110] - auxiliary power units (APU),
[0111] - turbogenerators for civil and military VTOL / CTOL aircraft and vehicles with distributed electric propulsion,
[0112] - etc.
Claims
CLAIMS 1. Aircraft turbomachine (10), comprising: - a centrifugal compressor (14) extending around a longitudinal axis (A) of the turbomachine, - an annular combustion chamber (24) extending around the longitudinal axis (A), - a heat exchanger (38) comprising a first circuit (38a) supplied with exhaust gas from the turbomachine, and a second circuit (38b) comprising at least one inlet (38ba) connected by a first annular system (40a) to at least one outlet (22) of the centrifugal compressor (14), and at least one outlet (38bb) connected by a second annular system (40b) to at least one inlet of the annular combustion chamber (24), the first and second systems extending around the longitudinal axis (A), characterized in that each of the first and second systems (40a, 40b) is sectorized and comprises at least two volutes (40a1, 40a2, 40b1, 40b2) forming system sectors and distributed around said longitudinal axis (A), each of the volutes (40a1, 40a2, 40b1, 40b2) comprising at one end circumferentially a first port (42, 46) and at an opposite circumferential end a second port (44, 48),and having an evolving passage section which is maximum at the first port (42, 46) and minimum at the second port (44, 48), the volutes (40a1, 40a2) of the first system (40a) having their second ports (44) which are inlet ports and which are connected to said at least one outlet (22) of the centrifugal compressor (14), and their first ports (42) which are outlet ports and which are connected to said at least one inlet (38ba) of the second circuit (38b), and the volutes (40b1, 40b2) of the second system (40b) having their first ports (46) which are inlet ports and which are connected to said at least one outlet (38bb) of the second circuit (38b), and their second ports (48) which are outlet ports and which are connected to said at least one inlet (36a) of the annular combustion chamber (24)., 2. Turbomachine (10) according to claim 1, wherein each of the first and second systems (40a, 40b) comprises two volutes (40a, 40a2, 40b1, 40b2) which each extend over at least 180° around the longitudinal axis (A).
3. Turbomachine (10) according to claim 1, in which each of the first and second systems (40a, 40b) comprises three or four scrolls.
4. Turbomachine (10) according to claim 2, in which the first ports (42) of the volutes (40a1, 40a2) of the first system (40a) are diametrically opposite relative to the longitudinal axis (A), and their second ports (44) are diametrically opposite relative to the longitudinal axis (A).
5. Turbomachine (10) according to claim 2 or 4, in which the first ports (46) of the volutes (40b1, 40b2) of the second system (40b) are diametrically opposite relative to the longitudinal axis (A), and their second ports (48) are diametrically opposite relative to the longitudinal axis (A).
6. Turbomachine (10) according to all of claims 4 and 5, in which the first ports (42) of the volutes (40a1, 40a2) of the first system (40a) are axially aligned with the first ports (46) of the volutes (40b1, 40b2) of the second system (40b), and the second ports (44) of the volutes (40a1, 40a2) of the first system (40a) are axially aligned with the second ports (48) of the volutes (40b1, 40b2) of the second system (40b).
7. Turbomachine (10) according to one of claims 2, and 4 to 6, in which the longitudinal axis (A) is an axis of symmetry for the volutes (40a1, 40a2) of the first system (40a), on the one hand, and for the volutes (40b1, 40b2) of the second system (40b), on the other hand.
8. Turbomachine (10) according to one of the preceding claims, in which the second ports (44, 48) of the volutes (40a1, 40a2, 40b1, 40b2) of the first and second systems (40a, 40b) are oriented in the radial direction, and the first ports (42, 46) of the volutes (40a1, 40a2, 40b1, 40b2) of the first and second systems (40a, 40b) are oriented in the tangential direction.
9. Turbomachine (10) according to claim 8, in which the second ports (44, 48) of the volutes (40a1, 40a2, 40b1, 40b2) of the first and second systems (40a, 40b) are connected to ends of bent ducts (50, 80), these bent ducts (50, 80) having opposite ends oriented parallel to the longitudinal axis (A).
10. Turbomachine (10) according to claim 9, in which the outlets of the bent conduits (50, 80) are each connected to a flexible bellows (60).
11. Turbomachine (10) according to one of claims 1 to 10, in which the first and second systems (40a, 40b) are axially attached to each other.
12. Turbomachine (10) according to one of claims 1 to 11, in which the second ports (48) of the second system (40b) comprise air flow straightener vanes (70).