Device for supplying fuel to the combustion chamber of a gas generator

Abstract

The invention relates to a device for supplying fuel to a combustion chamber of a gas generator, comprising: an injection wheel (14) for injecting fuel into the combustion chamber (18), a fuel supply rail (20) comprising an internal fuel circuit (30), the internal fuel circuit having a fuel discharge member (32), the fuel discharge member (32) supplying fuel to an annular injection chamber (24) formed between the rail (28, 44, 48, 52, 56) and the injection wheel (14), at least one dynamic annular seal (26) suitable for providing a seal between an annular face (34) of the fuel supply rail (28, 44, 48, 52, 56) and the injection wheel (14), characterized in that the fuel circuit (30) of the fuel supply rail comprises an annular fuel flow portion arranged radially at the dynamic annular seal (26).

Description

[0001] The technical field is fuel injection arrangements in combustion chambers of aircraft engines. Background Art

[0002] refer to Figure 1 Some turbomachines 1 , such as turbine engines, comprise a gas generator 10 comprising a rotating shaft 12 on which an injection wheel 14 is mounted, the injection wheel itself being rotatable.

[0003] The injection wheel has a plurality of orifices 16 leading to a combustion chamber 18. In this manner, the injection wheel, when rotating, centrifugally injects fuel into the combustion chamber 18. Figure 2 , the turbine also comprises a fuel supply rail 20, which is a fixed part with a rotating shape mounted around the shaft 12 of the gas generator 10. The fuel supply rail 20 delivers the fuel to the injection wheel. Therefore, the fuel supply rail 20 comprises an internal fuel circuit 22 leading to a cavity 24 or an annular injection chamber. In order to ensure the seal between the injection wheel 14 and the fuel supply rail 20, a plurality of dynamic seals 26, such as labyrinth seals 26, are provided. Seals 26 of this type, which are well known in the state of the art, comprise annular teeth 26a, which are carried by one of the fuel supply rail 20 and the injection wheel 14 and rub on an abradable annular portion of the other of the injection wheel 14 and the fuel supply rail 20.

[0004] However, it often happens that solid deposits of coke form between the annular teeth 26a, thus causing friction between the injection wheel 14 and the fuel supply rail 20. The friction may increase until the gas generator shaft is completely blocked and the engine cannot be started.

[0005] If the start is difficult, the operator performs the troubleshooting operations described in the turbomachinery maintenance manual. These investigations are usually lengthy and not very effective, since it may take a long time to detect the cause of the start difficulty (in this case, coking in the dynamic joints, in fact many other causes are also possible). Once the cause has been found, the tracks on the engine are cleaned, or the tracks are removed for cleaning or replacement. These operations mean that the turbomachine and therefore the aircraft on which it is installed are unexpectedly unusable, which may further require the cancellation of one or more planned flight missions. Therefore, these operations imply considerable costs.

[0006] It is therefore important to limit coke formation in the annular seal providing a seal between the injection wheel and the fuel supply rail.

[0007] The present invention aims to remedy these drawbacks in a simple, reliable and inexpensive manner. Summary of the invention

[0008] The present invention therefore relates to a device for supplying fuel to a combustion chamber of a gas generator, comprising:

[0009] - a fuel injection wheel for injecting fuel into the combustion chamber,

[0010] - a fuel supply rail comprising an internal fuel circuit having fuel discharge members supplying fuel to an annular injection chamber formed between the rail and the injection wheel,

[0011] - at least one dynamic annular seal adapted to provide a seal between the annular face of the fuel supply rail and the injection wheel,

[0012] Characteristically, the fuel circuit of the fuel supply rail comprises an annular fuel flow portion radially arranged at the dynamic annular seal.

[0013] Unlike the prior art, the fuel circuit is provided with an annular portion arranged exactly at the dynamic annular seal, which allows to reduce the temperature (typically below 150° C.) by the circulation of the fuel at the annular seal and thus prevent the formation of coke. When the seal comprises annular teeth, the accumulation of coke in the annular space formed between the annular teeth is prevented. The nominal operating conditions of the turbine can thus be maintained, since there is no risk of motor shaft blocking. The term “annular portion” does not refer to a 360° profiled portion, as will be apparent from the detailed description.

[0014] In one embodiment, the annular portion comprises at least a first turn which is arranged radially inside the dynamic seal and connected downstream to the fuel discharge member. This first turn has an upstream end connected to the upstream fuel passage and is connected downstream to the fuel discharge member.

[0015] Furthermore, the first turn may be formed near a first axial end of the dynamic seal, the first axial end being arranged along the seal opposite a second end arranged near the fuel discharge member. This positioning of the first turn allows the first end of the annular seal (which is the portion most susceptible to coke formation) to cool.

[0016] Furthermore, the annular portion may comprise at least one second turn which is arranged axially between the first turn and the second end of the annular seal and follows the first turn in the direction of the gas flow.

[0017] The annular seal may have an axial extent L, the first turn extending axially between -L / 2 and L, with the origin taken at the first axial end of the seal and the positive direction taken from the first end towards the second end.

[0018] The annular portion may be connected to a fuel discharge member including a plurality of fuel discharge ports in the injection chamber.

[0019] The fuel discharge member may include one or more circumferentially extending conduits connected upstream to the annular portion.

[0020] The annular surface of the track may be a radially outer annular surface, the annular portion of the fuel circuit being arranged radially within the radial annular surface.

[0021] According to another feature, the annular fuel flow portion can be arranged radially inside the annular seal or radially outside the annular seal.

[0022] The annular seal may include annular teeth axially spaced from one another, carried by one of the fuel supply rail and the injection wheel and adapted to frictionally engage an abradable annular portion of the other of the injection wheel and the fuel supply rail.

[0023] The radial annular portion may be arranged radially inside or outside the annular tooth.

[0024] The invention also relates to a turbomachine comprising a device such as described above. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] [ Figure 1 ] is a general diagram of a turbomachine in which the injection wheel "14" is integrated with the engine axis "12" and the annular combustion chamber "18", and

[0026] In the case of a gas turbine equipped with a fuel injection wheel, in [ Figure 2 ] shows a schematic representation of the working principle, as described above,

[0027] [ Figure 3 ] represents the first embodiment according to the present disclosure, and this figure includes Figure 3 A and Figure 3 The two parts of B, A and B, Figure 3 A and Figure 3 B shows an axial cross section and an external view of the track, respectively, with arrows schematically indicating the fuel flow,

[0028] [ Figure 4 ]yes Figure 3 3D representation of an alternative embodiment of (elliptical cross section of the fuel circuit),

[0029] [ Figure 5 ] represents the second embodiment according to the present disclosure, and this figure includes Figure 5 A and Figure 5 The two parts of B, A and B, Figure 5 A and Figure 5 B presents an axial cross section (part A) and an external view (part B) of the track, respectively, with arrows schematically indicating the fuel flow.

[0030] [ Figure 6] shows a third embodiment in axial cross section (the red rectangle schematically represents the cavity in which the fuel can flow),

[0031] [ Figure 7 ] represents the fourth embodiment according to the present disclosure, and this figure includes Figure 7 A and Figure 7 The two parts of B, A and B, Figure 7 A and Figure 7 B shows an axial cross section and an external view of the track, respectively, with arrows schematically indicating fuel flow. DETAILED DESCRIPTION

[0032] Reference now Figure 3 , which shows Figure 2 1 and 2. The fuel supply rail 28 is similar or identical to that shown in the drawings and is intended to cooperate with the injection wheel 14. The fuel supply rail 28 includes an internal fuel circuit 30 having a fuel discharge member 32 for supplying fuel to the injection chamber. The fuel circuit is represented by a bold line and the flow direction is represented by an arrow. The fuel discharge member 32 includes an annular duct 32b that does not extend through 360° and is connected to fuel discharge ports 32a that are evenly spaced around the axis of the turbine. The annular duct 32b includes a first circumferential duct 32b1 and a second circumferential duct 32b2. The fuel circuit 30 is Figure 3 It is shown schematically in B.

[0033] The fuel supply rail 28 comprises a radially outer annular face 34 intended to cooperate with a ring (not shown) made of an abradable material, from which radial annular teeth or tongues 26a extend. The dynamic seal thus formed comprises a first end 36 and a second end 38, the second end 38 being arranged near the fuel discharge member 32 and the first end 36 being located opposite.

[0034] In order to avoid the formation of coke at the first end, the fuel circuit 30 comprises an annular portion 40 which is formed exactly at the annular seal 26, i.e. axially at the annular seal 26 and, in this case, radially inside the annular seal 26 (schematically, the fuel circuit is shown with a circular cross section, but an elliptical cross section is also possible, e.g. Figure 4). More precisely, this annular portion 40 is formed by a first turn, the upstream end of which is connected to the fuel supply channel 42 and the downstream end of which is connected to the annular portion 40 or the first turn. It can be seen that the connection between the downstream end of the first turn 40 and the annular duct 32b is made at an angle substantially in the middle of the latter in order to reduce pressure losses in the annular duct. This first turn 40 is formed near the first end 36 of the annular seal 26. Therefore, any potential fuel backflow from the injection chamber 24 does not lead to coke formation, because the temperature at the annular teeth 26a of the first end 36 of the annular seal 26 is reduced compared to the prior art.

[0035] Figure 4 Display basis Figure 3 3D view of a fuel supply rail 44 of an alternative embodiment to the embodiment shown in FIG. In this view, the first turn 46 has an axial or longitudinal dimension (i.e., an elliptical and non-circular cross-section), i.e., along the axis of the gas turbine. In this case, where the annular seal 26 has an axial extent L, the first turn 46 is axially located between -L / 2 and L, with the origin taken at the first axial end 36 of the seal 26 and the positive direction taken from the first end 36 toward the second end 38. This turn 46 extends axially upstream from the first end 36 of the seal 26 to its downstream end.

[0036] Figure 5 A is a second embodiment of the supply rail 48, in which the annular portion 50 comprises a first turn 50a connected downstream in the direction of gas flow to a second turn 50b, which is formed radially inside the annular seal 26. The downstream end of the second turn 50b is connected to the fuel discharge member 32. As previously mentioned, the connection between the downstream end of the second turn 50b and the annular duct 32b is made at an angle substantially in the middle of the latter in order to reduce pressure losses in the duct.

[0037] In operation, fuel flows through the first turn 50a and then through the second turn 50b, and then simultaneously through the first circumferential conduit 32b1 and the second circumferential conduit 32b2, as shown in FIG. Figure 5 B. In this second embodiment, it will be appreciated that the first turn 50 b 1 and the second turn 50 b 2 together form an annular fuel flow portion 50 for reducing the temperature of the dynamic annular seal 26 .

[0038] Figure 6 A third embodiment of a fuel supply rail 52 is shown in which a cooling annular portion 54 of the annular seal 26 is formed by an axial extension of a portion of the annular fuel discharge conduit 32 located radially within the annular seal 26 .

[0039] Figure 7A fourth embodiment of a fuel supply rail 56 is shown in which the downstream end of the fuel supply passage 42 is connected at the midpoint 58 of an annular conduit 60 including a first circumferential conduit 60a and a second circumferential conduit 60b which, in operation, form a cooling annular portion of the annular seal 26. The downstream end of the first circumferential conduit 60a is connected to a third circumferential conduit 62 extending circumferentially to the midpoint 58. The downstream end of the second circumferential conduit 60b is connected to a third circumferential conduit 64 extending circumferentially to the midpoint 58.

[0040] It should be understood that the downstream ends of the first 60a and second 60b circumferential conduits do not communicate with each other. In operation, fuel flows through the fuel supply passage 42 and then splits into a first fuel flow in the first circumferential conduit 60a and then in the third circumferential conduit 62, and splits into a second fuel flow in the circumferential conduit 60b and then in the fourth circumferential conduit 64.

Claims

1. A device for supplying fuel to a combustion chamber of a gas generator, comprising: - an injection wheel (14) for injecting fuel into the combustion chamber (18), a fuel supply rail (20, 28, 44, 48, 52, 56) comprising an internal fuel circuit (30) having a fuel discharge member (32) which supplies fuel to an annular injection chamber (24) formed between the fuel supply rail (20, 28, 44, 48, 52, 56) and the injection wheel (14), - at least one dynamic annular seal (26) adapted to provide a seal between an annular face (34) of the fuel supply rail (20, 28, 44, 48, 52, 56) and the injection wheel (14), Characterized in that the fuel circuit (30) of the fuel supply rail comprises an annular fuel flow portion (40, 50) radially arranged at the dynamic annular seal (26).

2. The device according to claim 1, characterized in that The annular fuel flow portion (40, 50) includes at least a first turn (46, 50a) disposed radially inwardly of the dynamic annular seal (26) and connected downstream to the fuel discharge member (32).

3. The device according to claim 2, characterized in that The first turn (46, 50a) is formed adjacent a first axial end (36) of the dynamic annular seal, the first axial end being disposed along the dynamic annular seal (26) opposite a second end (38) disposed adjacent the fuel discharge member (32).

4. The device according to claim 2 or 3, characterized in that The annular fuel flow portion (40, 50) includes at least one second turn (50b) disposed axially between the first turn (50a) and the second end (38) of the dynamic annular seal (26) and fluidly following the first turn (50a).

5. The device according to claim 3, characterized in that The dynamic annular seal (26) has an axial extent L, the first turn (46) extending axially between -L / 2 and L, with the origin being taken at the first axial end of the dynamic annular seal and the positive direction being taken from the first end towards the second end.

6. The device according to claim 1, characterized in that The annular fuel flow portion is connected to the fuel discharge member (32) which includes a plurality of fuel discharge ports (32a) in the injection chamber (24).

7. The device according to claim 6, characterized in that The fuel discharge member (32) includes one or more circumferentially extending conduits (32b1, 32b2, 62, 64) connected upstream to the annular fuel flow portion.

8. The device according to claim 1, characterized in that The annular surface (34) of the fuel supply rail is a radially outer annular surface, and the annular fuel flow portion of the fuel circuit (30) is arranged radially inside the radial annular surface (34).

9. The device according to claim 1, characterized in that The annular fuel flow portion (40, 50) is arranged radially inside the dynamic annular seal (26) or radially outside the dynamic annular seal (26).

10. The device according to claim 1, characterized in that The dynamic annular seal (26) includes annular teeth axially spaced from one another, the annular teeth being carried by one of the fuel supply rail (20, 28, 44, 48, 52, 56) and the injection wheel (14) and adapted to frictionally engage an abradable annular portion of the other of the injection wheel (14) and the fuel supply rail (20, 28, 44, 48, 52, 56).

11. The device according to claim 10, characterized in that The radial annular portion is arranged radially inside or outside the annular tooth.

12. A turbomachine comprising a device according to any one of claims 1 to 11.

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