RADIAL SWIRL DEVICE FOR TURBOMACHINE COMBUSTION CHAMBER.

Abstract

The invention relates to a radial swirl device (80') for a turbomachine combustion chamber, said radial swirl device (80') being configured to be positioned within said turbomachine in a mounting position in which said radial swirl device (80') is traversed by an airflow F arriving radially on said radial swirl device (80') and deviating axially downstream of said radial swirl device (80') when said turbomachine is in operation, said radial swirl device (80') comprising a first circular cylindrical disk extending about a longitudinal axis L, said first circular cylindrical disk being delimited by an upstream face (810'), a downstream face extending orthogonally to said longitudinal axis (L), and an external circumferential surface connecting said upstream face (810') and said downstream face,said first circular cylindrical disk (81') comprising a first airflow channel. Figure 3A.

Description

Title of the invention: RADIAL SWIRL DEVICE FOR CHAMBER TURBOMACHINE COMBUSTION. Scope of the invention

[0001] The present invention relates to the field of aircraft turbomachinery.

[0002] More particularly, the invention relates to a swirling device radial intended to be provided close to the combustion chamber feed of an aircraft turbomachine. Prior art

[0003] Classically, a turbomachine comprises a gas generator on either side of which are arranged along a longitudinal axis of the turbomachine a low pressure compressor and a low pressure turbine, this gas generator comprising a high pressure compressor, a combustion chamber and a high pressure turbine.

[0004] The combustion chamber is, as is known, the element where a fuel mixes with an airflow passing through this turbomachine. Much work is being carried out to optimize this portion of the turbomachine, and in particular to improve the quality of combustion and to stabilize this combustion within the combustion chamber.

[0005] To achieve this, it is common to implement a swirling device at the combustion chamber feed to generate turbulence and a swirling burst.

[0006] Such a device thus makes it possible to improve many combustion parameters such as consumption or the space required to carry out this combustion, and also makes it possible to create a rotating flow in a more uniform way, which allows the combustion flame to be reduced in the combustion chamber and which thus offers the possibility of reducing the length of the combustion chamber along the longitudinal axis of this chamber.

[0007] However, the gyration, which is the ratio between the tangential velocity of the airflow introduced by the swirling device and the axial velocity of the airflow introduced by the swirling device, must be sufficiently high to generate a satisfactory level of turbulence. On the other hand, this satisfactory level of turbulence can cause vortex bursting near a fuel injector due to the axial velocity deficit at the center of the generated vortex. Such premature bursting can create a risk of backfire, particularly for certain fuel types that prove to be very reactive, and can also cause a high pressure drop, which is not acceptable.

[0008] There is therefore a need to provide a solution to address the problem of axial velocity deficit at the center of the generated vortex in order to limit or even eliminate the risks of premature vortex bursting. Description of the invention

[0009] The invention aims to remedy at least in part the aforementioned drawbacks relating to prior art techniques.

[0010] To this end, the invention relates to a radial swirl device for a turbomachine combustion chamber, said radial swirl device being configured to be able to be positioned within said turbomachine in a mounting position in which said radial swirl device is traversed by an airflow F arriving radially on said radial swirl device and moving axially away downstream of said radial swirl device when said turbomachine is in operation, said radial swirl device comprising a first circular cylindrical disk extending around a longitudinal axis L, said first circular cylindrical disk being delimited by an upstream face, a downstream face extending orthogonally to said longitudinal axis L, and an external circumferential surface connecting said upstream face and said downstream face,said first circular cylindrical disc comprising a first airflow channel comprising: , - a first central circular portion hollowed out from said upstream face at the level of a radially internal portion of said first circular cylindrical disk; - a plurality of arms, each being hollowed out from said upstream face and extending from a radial end opening at the location of said external circumferential surface of said first circular cylindrical disk to said first central circular portion such that each of said arms is traversed by a portion of said airflow F between said radial end and said first central circular portion when said radial swirling device is in the mounting position and when said turbomachine is in operation, each of said arms extending in a direction offset from a radial direction of said first circular cylindrical disk,

[0011] each of said arms being delimited by a bottom wall substantially orthogonal to said longitudinal axis L extended on both sides by two lateral walls, at least one of said two lateral walls having a volute profile.

[0012] Thus, the proposed solution makes it possible to push the vortex bursting downstream of the axial vortex device and therefore to reduce the level of gyration and thus the axial velocity deficit at the center of the vortex, which not only reduces the pressure loss, but also reduces the risk of flashback, while maintaining significant levels of gyration on the periphery, which are favorable to combustion quality.

[0013] By volute profile, it is understood here that the inclination of one of the two lateral walls varies progressively over the radial extent of this lateral wall.

[0014] According to a particular aspect of at least one embodiment of the invention, said first airflow channel has a spiral shape, said arms being radially uniformly distributed on the upstream face of said first circular cylindrical disc.

[0015] According to a particular aspect of at least one embodiment of the invention, each of said arms extends along an offset direction RI at an angle between 20 and 50 degrees with respect to a radial direction R of said first circular cylindrical disk.

[0016] According to a particular aspect of at least one embodiment of the invention, each of said arms has a quadrilateral radial section with three right angles.

[0017] According to a particular aspect of at least one embodiment of the invention, said airflow channel comprises between three and twenty arms radially uniformly distributed on the upstream face of said first circular cylindrical disc.

[0018] In this case, preferably, said airflow channel comprises between eight and twelve arms radially uniformly distributed on the upstream face of said first circular cylindrical disk.

[0019] According to a particular aspect of at least one embodiment of the invention, each arm has a length between said radial end and said first central circular portion of between 10% and 45% of a diameter of said first circular cylindrical disk.

[0020] According to a particular aspect of at least one embodiment of the invention, said first circular cylindrical disc has a diameter between 0.5cm and 1.5cm.

[0021] According to a particular aspect of at least one embodiment of the invention, the radial swirling device comprises a second circular cylindrical disk concentric with said first circular cylindrical disk and having a downstream face positioned opposite said upstream face of said first circular cylindrical disk, said downstream face of said second circular cylindrical disk being connected to said upstream face of said first circular cylindrical disk by means of a plurality of walls projecting longitudinally from said downstream face of said second circular cylindrical disk, so as to form a second flow channel of airflow between the first circular cylindrical disc and the second circular cylindrical disc, said second airflow channel opening into the first airflow channel at the location of said first central circular portion.

[0022] According to a particular aspect of at least one embodiment of the invention, said walls are oriented along a radial direction of said second circular cylindrical disk.

[0023] According to a particular aspect of at least one embodiment of the invention, said second airflow channel has a second circular central portion opening into said first circular central portion, said first circular central portion having a first diameter DI greater than a second diameter D2 of said second circular central portion.

[0024] The invention also relates to a turbomachine comprising a combustion chamber assembly including at least one radial swirl device according to one of the aforementioned embodiments, said at least one radial swirl device being positioned within said turbomachine in an assembly position in which said at least one radial swirl device is traversed by an airflow F arriving radially on said at least one radial swirl device and moving axially away downstream of said at least one radial swirl device when said turbomachine is in operation. Presentation of the figures

[0025] The invention, as well as the various advantages it presents, will be more easily understood in the light of the following description of an illustrative and non-limiting embodiment thereof, and of the accompanying drawings, among which: [Fig.1] is a schematic cross-sectional view of an aircraft turbomachine; [Fig.2A], [Fig.2B] and [Fig.2C] are perspective and front views illustrating a set according to earlier art; [Fig.3A], [Fig.3B] are respectively perspective and front views of a radial swirling device according to a first embodiment of the invention; [Fig.3C] is a schematic representation of a section of an arm of the first airflow channel according to the first embodiment; [Fig. 3D] is another perspective view of a radial swirling device according to the first embodiment of the invention, and [Fig.4A] and [Fig.4B] are perspective and front views respectively of a radial swirling device according to a second embodiment of the invention.

[0026] Detailed description of an embodiment of the invention

[0027] With reference to [Fig. 1], a twin-spool, high-bypass turbojet engine 1 is shown. As described previously, a turbojet engine 1 conventionally comprises a gas generator 2 on either side of which are arranged a low-pressure compressor 4 and a low-pressure turbine 12. This gas generator 2 includes a high-pressure compressor 6, a combustion chamber 8, and a high-pressure turbine 10. Hereafter, the terms "forward" and "rear" are considered in a direction 14 opposite to the main gas flow direction within the turbojet engine, this direction 14 being parallel to its longitudinal axis 3. Conversely, the terms "upstream" and "downstream" are considered in the direction of the main gas flow within the turbojet engine.

[0028] The low-pressure compressor 4 and the low-pressure turbine 12 form a low-pressure unit and are connected to each other by a low-pressure shaft 11 centered on the axis 3. Similarly, the high-pressure compressor 6 and the high-pressure turbine 10 form a high-pressure unit and are connected to each other by a high-pressure shaft 13 centered on the axis 3 and arranged around the low-pressure shaft 11. The shafts are supported by rolling bearings 19, which are lubricated by being arranged in oil chambers. The same applies to the blower hub 17, which is also supported by rolling bearings 19.

[0029] The turbojet 1 also includes, at the front of the gas generator 2 and the low-pressure compressor 4, a single fan 15 which is arranged here directly behind an air inlet cone of the engine. The fan 15 rotates about axis 3 and is surrounded by a fan housing. In [Fig. 1], it is not driven directly by the low-pressure shaft 11, but only indirectly by this shaft via a reduction gear 20, which allows it to rotate at a slower speed. However, a solution with direct drive of the fan 15 by the low-pressure shaft 11 falls within the scope of the invention.

[0030] Furthermore, the turbojet 1 defines a primary flow 16 intended to be traversed by a primary flow, as well as a secondary flow 18 intended to be traversed by a secondary flow located radially outwards with respect to the primary flow, the fan flow thus being divided. As is known to those skilled in the art, the secondary flow 18 is delimited radially outwards in part by an outer shell 23, preferably metallic, extending rearwards from the fan casing.

[0031] Although not shown, the turbojet 1 is equipped with a set of equipment, for example, a fuel pump, hydraulic pump, alternator, starter, variable stator timing (VSV) actuator, wastegate actuator, and a power generator. This includes equipment for lubricating the gearbox 19. This equipment is driven by an accessory gearbox or AGB (not shown), which is also lubricated.

[0032] Downstream of the blower 15, in the secondary channel 18, a ring of guide vanes is provided, which are in this case outlet guide vanes 24 (or OGVs, from the English "Outlet Guide Vane"). These stator vanes 24 connect the outer shell 23 to a housing 26 surrounding the low-pressure compressor 4. They are spaced circumferentially from each other and allow the secondary flow to be straightened after it passes through the blower 15. In addition, these vanes 24 can also fulfill a structural function, as is the case in the embodiments described herein. They ensure the transfer of forces from the reducer and bearings 19 of the motor shafts and the fan hub, to the outer shell 23. Then, these forces can pass through a motor attachment 30 fixed to the shell and connecting the turbojet to a mounting mast (not shown) of the aircraft.

[0033] Finally, the outlet guide vanes 24 provide a third heat exchanger function between the secondary airflow passing through the vane ring, and the lubricant circulating inside these vanes 24. The lubricant intended to be cooled by the outlet guide vanes 24 is that used in particular for the lubrication of the reducer 19.

[0034] As discussed previously, the combustion chamber is where fuel mixes with an airflow passing through this turbomachine. To improve combustion quality and stabilize combustion within the combustion chamber, the invention provides for the implementation of at least one radial swirling device within a turbomachine combustion chamber assembly 1.

[0035] A conventional radial swirling device is now presented in relation to figures 2A to 2C.

[0036] The turbomachine combustion chamber assembly therefore comprises at least one radial swirl device 80 which is positioned within the turbomachine in a mounting position. In this mounting position, the radial swirl device is traversed by an airflow arriving radially on the radial swirl device and deviating axially downstream of the radial swirl device when the turbomachine is in operation.

[0037] As can be seen more particularly in Figures 2A to 2C, a conventional radial swirling device 80 comprises a first cylindrical disk circular 81 extending around a longitudinal axis L and which is delimited by an upstream face 810, a downstream face 811 extending orthogonally to the longitudinal axis L, and an external circumferential surface connecting the upstream face 810 and the downstream face 811.

[0038] As can be seen, the first circular cylindrical disc 81 comprises a first airflow channel comprising: - a first central circular portion 82 hollowed out from the upstream face 810 at the level of a radially internal portion of the first circular cylindrical disk 81; - a plurality of arms 83, each being hollowed out from the upstream face 810 and extending from a radial end 830 opening at the point of the external circumferential surface of the first circular cylindrical disk 81 to the first central circular portion 82 so that each of the arms 83 is traversed by a portion of airflow F between the radial end 830 and the first central circular portion 82 when the radial swirl device is in the mounting position and when the turbomachine is in operation.

[0039] Consequently, the airflow F arriving radially at the radial swirl device 80 enters each of the arms 83 through a radial end 830 and passes through the arm until it reaches the first central circular portion 82 of the first airflow channel. The airflow then deviates axially downstream of the radial swirl device 80 from the first central circular portion 82 of the first airflow channel.

[0040] Each of the arms 83 extends along a direction offset RI with respect to a radial direction R of the first circular cylindrical disk 81.

[0041] In other words the arms do not extend along a radial direction R of the first circular cylindrical disk 81.

[0042] As described previously, such a device can cause a vortex burst near a fuel injector due to the axial velocity deficit at the center of the generated vortex, which can create a risk of flashback, particularly for certain types of fuels which are very reactive, and can also cause a high pressure drop, which is not acceptable.

[0043] To achieve this, the invention proposes to implement a radial swirling device in which each of the arms is delimited by a bottom wall substantially orthogonal to said longitudinal axis, extended on either side by two lateral walls, with at least one of the two lateral walls having a volute profile.

[0044] A first embodiment of the invention is thus presented in relation to figures 3A to 3C.

[0045] As illustrated in these figures, the radial swirling device 80' comprises a first circular cylindrical disk 81' extending around a longitudinal axis L, and which is delimited by an upstream face 810', a downstream face 811' extending orthogonally to the longitudinal axis L, and an external circumferential surface connecting the upstream face 810' and the downstream face 811'.

[0046] This first circular cylindrical disc 81' comprises a first airflow channel including: - a first central circular portion 82' hollowed out from the upstream face 810' at the level of a radially internal portion of the first circular cylindrical disk 81'; - a plurality of arms 83', each being hollowed out from the upstream face 810' and extending from a radial end 830' opening at the point of the external circumferential surface of the first circular cylindrical disk 81' to the first central circular portion 82' so that each of the arms 83' is traversed by a portion of the airflow F between the radial end 830' and the first central circular portion 82' when the radial swirl device 80' is in the mounting position and when the turbomachine is in operation, each of the arms 83' extending in a direction offset RI with respect to a radial direction R of the first circular cylindrical disk 81'.

[0047] More particularly, each of the arms 83' extends along an offset direction RI at an angle between 20° and 50° degrees relative to a radial direction R of the first circular cylindrical disk 81'.

[0048] It should be noted that this offset value is to be considered here in absolute value.

[0049] According to the invention, each of the arms 83' is delimited by a bottom wall 832' substantially orthogonal to the longitudinal axis L extended on either side by two lateral walls 831', at least one of the two lateral walls 831' having a volute profile.

[0050] Such a radial vortexing device thus makes it possible to push the vortex bursting downstream and therefore to reduce the level of gyration and the axial velocity deficit at the center of the vortex

[0051] This bottom wall and these two side walls define a radial section for each of the arms.

[0052] Here, in this embodiment, and as seen in [Fig.3C], the radial section is quadrilateral with three right angles and a fourth angle presenting an evolving curvature defining the volute.

[0053] In other words, the evolving curvature has a progressive variable inclination, that is to say varying in the same direction, over the radial extent of this lateral wall, that is to say over the radial extent of the arm.

[0054] In other words, the inclination of one of the two lateral walls varies progressively over the radial extent of this lateral wall between the radial end 830' and the first central circular portion 82'.

[0055] It should be noted that according to one variant, the two side walls could have a volute profile.

[0056] More particularly, according to one variant the two lateral walls could have a volute profile, these two profiles being complementary so that the section of the arm has a constant surface area.

[0057] In this embodiment, the first airflow channel has a spiral shape. In this spiral shape, the arms 83' are radially uniformly distributed on the upstream face of the first circular cylindrical disk 81'.

[0058] More specifically, in this embodiment, the airflow channel comprises ten arms 83' radially uniformly distributed on the upstream face of the first circular cylindrical disk 81'.

[0059] Generally, the airflow channel can comprise between three and twenty arms radially uniformly distributed on the upstream face of the first circular cylindrical disk.

[0060] Preferably the airflow channel can comprise between eight and twelve arms, the arms being radially uniformly distributed on the upstream face of the first circular cylindrical disk.

[0061] Moreover, each arm 83' has a length between the radial end 830' and the first central circular portion 82' of between 10% and 45% of a diameter of the first circular cylindrical disk 81'.

[0062] This diameter of the first circular cylindrical disc 81' can be, according to the embodiments, between 0.5 cm and 1.5 cm. A second embodiment of the invention is now presented in relation to Figures 4A and 4B.

[0063] In this second embodiment, the first circular cylindrical ring 81' is identical to the first circular cylindrical ring 81' of the first embodiment of the invention (the volute side walls not being illustrated).

[0064] As illustrated, the radial swirling device 80' ' here comprises a second circular cylindrical disk 85 concentric with the first circular cylindrical disk 81'.

[0065] This second circular cylindrical disk 85 has a downstream face 850 arranged opposite the upstream face 811' of the first circular cylindrical disk 81'.

[0066] In addition, the downstream face 850 of the second circular cylindrical disc 85 is connected to the upstream face 811' of the first circular cylindrical disc 81' by means of a plurality of walls 86 projecting longitudinally from the downstream face 850 of the second circular cylindrical disc 85, so as to form a second airflow channel between the first circular cylindrical disc 81' and the second circular cylindrical disc 85.

[0067] The second airflow channel opens into the first airflow channel at the location of the first circular central portion 82'. In this way, when the radial swirl device is in a mounting position and the turbomachine is in operation, the airflow F arriving radially on the radial swirl device 80'' at the level of the second airflow channel then passes into the first airflow channel through the first circular central portion 82' and then deviates axially downstream of the radial swirl device 80" from this first circular central portion 82' of the first airflow channel.

[0068] More specifically, the second airflow channel has a second central circular portion 87 opening into the first central circular portion 82'.

[0069] In order to allow good circulation of the airflow, the first central circular portion 82' has a first diameter DI greater than a second diameter D2 of the second central circular portion 87.

[0070] As illustrated, the walls 86 are here three in number and are oriented along a radial direction of the second circular cylindrical disk 85. They have a rectangular shape.

[0071] According to one variant, a greater number of walls could be implemented. For example, the number of walls could be equal to the number of arms of the first airflow channel.

[0072] It could also be provided that these walls are not oriented along a radial direction of the second circular cylindrical disk but that they are inclined with respect to this radial direction of the second circular cylindrical disk.

Claims

1. Demands Radial swirl device (80', 80") for turbomachine combustion chamber (1), said radial swirl device (80', 80") being configured to be able to be positioned within said turbomachine in a mounting position in which said radial swirl device (80', 80") is traversed by an airflow (F) arriving radially on said radial swirl device (80', 80") and moving axially away downstream of said radial swirl device (80', 80") when said turbomachine (1) is in operation, said radial swirl device (80', 80") comprising a first circular cylindrical disk (81') extending about a longitudinal axis (L), said first circular cylindrical disk (81') being delimited by an upstream face (810'), a downstream face (811') extending orthogonally to said longitudinal axis (L),and an external circumferential surface connecting said upstream face (810') and said downstream face (811'), said first circular cylindrical disk (81') comprising a first airflow channel comprising:, - a first central circular portion (82') hollowed out from said upstream face (810') at the level of a radially internal portion of said first circular cylindrical disk (81'); - a plurality of arms (83'), each being hollowed out from said upstream face (810') and extending from a radial end (830') opening at the location of said external circumferential surface of said first circular cylindrical disk (81') to said first central circular portion (82') such that each of said arms (83') is traversed by a portion of said airflow (F) between said radial end (830') and said first central circular portion (82') when said radial swirl device (80', 80") is in the mounting position and when said turbomachine (1) is in operation, each of said arms (83') extending in an offset direction (RI) with respect to a radial direction (R) of said first circular cylindrical disk (81'), each of the said arms (83') being delimited by a bottom wall (832') substantially orthogonal to the said longitudinal axis (L) extended on either side by two lateral walls (831', 833'), at least one of the said two lateral walls (831', 833') having a volute profile.

2. Radial swirling device (80', 80") according to claim 1, characterized in that said first airflow channel has a spiral shape, said arms (83') being radially uniformly distributed on the upstream face of said first circular cylindrical disk (81').

3. Radial swirling device (80', 80") according to any one of claims 1 or 2, characterized in that each of said arms (83') extends in an offset direction (RI) at an angle between 20° and 50° with respect to a radial direction (R) of said first circular cylindrical disk (81').

4. Radial swirling device (80', 80") according to any one of claims 1 to 3, characterized in that said airflow channel comprises between three and twenty arms (83'), preferably between eight and twelve arms (83'), said arms (83') being radially uniformly distributed over the upstream face of said first circular cylindrical disk (81').

5. Axial swirling device (80', 80") according to any one of the preceding claims, characterized in that each arm (83') has a length between said radial end (830') and said first central circular portion (82') of between 10% and 45% of a diameter of said first cylindrical circular disk (81').

6. Axial swirling device (80', 80") according to any one of the preceding claims, characterized in that each arm (83') has a quadrilateral radial section with three right angles.

7. Axial swirling device (80', 80") according to any one of the preceding claims, characterized in that said first circular cylindrical disk (81') has a diameter between 0.5cm and 1.5cm.

8. Radial swirling device (80', 80") according to any one of the preceding claims, characterized in that it comprises a second circular cylindrical disk (85) concentric with said first circular cylindrical disk (81') and having a downstream face (850) positioned opposite said upstream face (811') said first circular cylindrical disc (81'), said downstream face (850) of said second circular cylindrical disc (85) being connected to said upstream face (811') of said first circular cylindrical disc (81') by means of a plurality of walls (86) projecting longitudinally from said downstream face (850) of said second circular cylindrical disc (85), so as to form a second airflow channel between the first circular cylindrical disc (81') and the second circular cylindrical disc 85, said second airflow channel opening into the first airflow channel at the location of said first central circular portion (82').

9. Radial swirling device (80', 80") according to the preceding claim, characterized in that said walls (86) are oriented along a radial direction of said second circular cylindrical disk (85).

10. Radial swirling device (80', 80") according to the preceding claim, characterized in that said second airflow channel has a second circular central portion (87) opening into said first circular central portion (82), said first circular central portion (82) having a first diameter (D1) greater than a second diameter (D2) of said second circular central portion (82).

11. Turbomachine comprising a combustion chamber assembly including at least one radial swirl device (80', 80") according to any one of claims 1 to 10, said at least one radial swirl device (80', 80") being positioned within said turbomachine in a mounting position in which said radial swirl device (80', 80") is traversed by an airflow (F) arriving radially on said radial swirl device (80', 80") and moving axially away downstream of said radial swirl device (80', 80") when said turbomachine (1) is in operation.

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