TURBO ENGINE OF AN AIRCRAFT CONTAINING A DEVICE FOR PREVENTING COKE DEPOSIT IN A PIPE

Description

Technical field of the invention

[0001] The present invention relates to the general field of aeronautics. It relates more particularly to an aircraft turbomachine. Technical background

[0002] The technical background includes, in particular, documents US-B2-9,644,495, EP-A2-0 822 345 and EP-A1-2 900 974.

[0003] Conventionally, an aircraft turbomachine comprises a gas generator including, along a longitudinal axis, at least one compressor, one combustion chamber, and at least one turbine.

[0004] An airflow enters the gas generator and is compressed in the compressor(s). This compressed airflow is mixed with fuel and burned in the combustion chamber. The combustion gases are then expanded in the turbine(s). This expansion causes the turbine rotor(s) to rotate, which in turn causes the compressor rotor(s) to rotate. The combustion gases are expelled through a nozzle to provide thrust, which can be added to the thrust provided by at least one propeller of the turbomachine.

[0005] To operate, the turbomachine requires fluids such as fuel to supply the combustion chamber, and oil to lubricate mechanical components such as rotor guide bearings. For this purpose, the turbomachine includes fluid supply lines. Specifically, the turbomachine includes one or more oil supply lines for oil jets on bearings, for example. The turbomachine also includes one or more fuel supply lines for fuel injectors in the combustion chamber.

[0006] During operation or when the engine is off, significant temperatures are reached within the turbomachine, and the oil and fuel can also reach relatively high temperatures. These high temperatures can promote the formation of coke in the lines. In this application, "coke" refers to a solid mass resulting from the deposition and accumulation of oil or fuel residues, linked to the thermal degradation of this liquid. This phenomenon is called coking and can eventually lead to partial or even total blockage of the line.

[0007] When coke deposits lead to a significant decrease in the oil flow rate injected to the bearings, for example, rapid and severe bearing failure can occur (bearing seizure), causing significant damage to the turbomachine. Therefore, coking of the bearing oil supply line in hot areas is a major safety and reliability issue. It is thus important to prevent or limit this phenomenon, or to find a solution to eliminate the coke that can form in the lines. One solution is to thermally insulate the lines to limit the heating of the fluid by thermal radiation from the hot engine parts (see, for example, FR-A1-3 041 700). Another solution is to ventilate the lines to also limit fluid heating. However, these solutions are relatively complex and expensive to implement, and are therefore not entirely satisfactory.Furthermore, these solutions address the thermal aspect of the problem, which is its source. However, the engine shutdown phase remains problematic since there is no longer any oil or air flow to dissipate the heat stored by the hot engine parts.

[0008] The present invention offers a simple, effective and economical solution to this need. Summary of the invention

[0009] The present invention proposes an aircraft turbomachine, comprising a gas generator including along a longitudinal axis at least one compressor, one combustion chamber and at least one turbine, the turbomachine further comprising at least one liquid supply line with at least one oil nozzle, this line comprising straight portions and angled portions and comprising at least one zone in which the liquid is likely to coke, characterized in that it comprises at least one turbulence element projecting at the level of said at least one zone in the line.

[0010] The present invention proposes equipping the pipeline with one or more internal turbulence elements so that these elements generate turbulence in the liquid flow, thereby cleaning the pipeline by dislodging any coke deposits. The turbulence elements are therefore preferably positioned in areas where coke is likely to form. These turbulence elements enable self-cleaning of the pipeline, which is advantageous compared to prior art solutions.

[0011] The turbomachine may include one or more of the following features, taken alone or in combination with each other: The pipe comprises several successive zones in which the liquid is likely to coke, with at least one turbulent element located at each of these zones in the pipe. The turbulent elements are of the same type; the turbulent elements are of different types; the turbulent element(s) is an obstacle or guide in the form of a stud, fin, helix, net, or twisted strip; the turbulent element(s) pass through all or part of the pipe; the pipe supplies oil to a nozzle that is configured to lubricate at least one bearing of the turbomachine.

[0012] The present invention also relates to a method for decoking a liquid supply line, intended to be implemented in a turbomachine according to the invention, comprising: a first phase of operation of the gas generator in which liquid is conveyed through the pipe to at least one oil nozzle, for the purpose of supplying it with this liquid, a second phase of shutdown of the gas generator in which coke is likely to form in said at least one area of ​​the pipe, a third phase of restart of the gas generator in which liquid is conveyed through the pipe to said oil nozzle, said at least one turbulence element generating turbulence in the liquid which is configured to detach and evacuate the coke from said at least one area.

[0013] The process according to the invention is particularly advantageous because it allows for the automatic removal of coke deposits from the pipe during each start-stop cycle without human intervention or any specific method. During the restart and engine operation phases of the following cycle, the element(s) generate turbulence that cleans the pipe by dislodging and dislodging any small coke deposits. Unlike prior art, the succession of such start-stop cycles will not lead to a progressive accumulation of coke. Brief description of the figures

[0014] Other features and advantages of the invention will become apparent upon reading the detailed description that follows, for an understanding of which reference should be made to the accompanying drawings in which: [ Fig.1 ] there figure 1is a schematic axial cross-sectional view of an aircraft turbomachine; [ Fig. 2 ] there figure 2 is a larger scale and more detailed schematic view of part of the turbomachine of the figure 1 ; Fig.3 ] there figure 3 is a schematic perspective view of part of a liquid feed line of the turbomachine of the figure 1 ; Fig. 4a-4b ] THE figures 4a and 4b represent, in a very schematic way, examples of turbulence elements for a liquid supply line; [ Fig. 4c-4d ] THE figures 4c and 4d represent, in a very schematic way, other examples of turbulence elements for a liquid supply line; and [ Fig. 4e ] there figure 4e represents in a very schematic way another example of a turbulence element for a liquid supply line. Detailed description of the invention

[0015] There figure 1shows a turbomachine 10 of an aircraft and more particularly of a helicopter although this application is not limiting.

[0016] The turbomachine 10 essentially comprises a gas generator 12 which includes along a longitudinal axis X at least one compressor 14, one combustion chamber 16, and at least one turbine 18.

[0017] There figure 2 shows in more detail the environment around the combustion chamber 16 and the turbine 18. This figure 2 shows a liquid supply line 20, and more particularly an oil supply line, to at least one oil jet 22.

[0018] The conduit 20 has an upstream end 20a and a downstream end 20b with reference to the oil flow in the conduit 20. The upstream end 20a, located on the left in the drawing, is connected to an oil source, for example via a pump. The downstream end 20b is connected to at least one nozzle 22 which is configured to spray oil onto one or more guide bearings 24 of the turbine rotor(s).

[0019] Pipe 20 comprises straight sections 21a, 21b and angled sections 21c, 21d. In the example shown, pipe 20 comprises: a first straight portion 21a which extends substantially radially downstream of the combustion chamber 16, a right-angled angled portion 21c located at the downstream end of the straight portion 21a, a straight portion 21b which extends radially with respect to the X axis from the angled portion 21c; this straight portion 21a passes through a distributor 30 of the turbine 18 and therefore through the flow path of the gas flow in the turbine, and a U- or V-shaped angled portion 21d which is located radially inside the combustion chamber 16, and which connects the radially internal end of the straight portion 21b to the nozzles 22, for example via a mounting flange 32 (cf. figure 3 ).

[0020] Line 20 includes at least one area where the oil is likely to coke. figure 3It shows several successive zones of this type with arrows. Pipe 20 may have zones distributed along its entire length from its upstream end to its downstream end.

[0021] According to the invention, the conduit 20 comprises at least one turbulence element in the zone or each of the zones of the conduit.

[0022] The turbulent elements can be of the same type or of different types.

[0023] THE figures 4a to 4e show several examples of the implementation of turbulence elements.

[0024] Each of these turbulence elements can be an obstacle (block, fin, ...) or a guide (, propeller, net, twisted band, ...).

[0025] There figure 4a shows a turbulence element 40 in the form of a cylindrical stud. This stud protrudes from an internal surface of the pipe 20 and generates turbulence in the oil flow.

[0026] There figure 4bshows a turbulence element 42 in the form of fins or blades. This element has an aerodynamic profile and protrudes from an internal surface of the pipe 20 to generate turbulence in the form of wakes in the oil flow.

[0027] There figure 4c shows a turbulence element 44 in the form of helices or helical ribs or helical mesh, projecting from an internal surface of the conduit 20 or engaged in the conduit 20 to generate turbulence in the oil flow.

[0028] There figure 4d shows a turbulence element 46 in the form of twisted bands which is engaged in the conduit 20 to generate turbulence in the oil flow.

[0029] There figure 4eFigure 48 shows a turbulent element in the form of a propeller, which is engaged or formed in the conduit 20 to generate turbulence in the oil flow. The propeller comprises an annular row of blades, as is the case with a fan propeller, for example. This propeller is fixed within the conduit 20.

[0030] The conduit 20 mentioned above has been described in relation to an oil supply. In an example that is not part of the claimed invention, the conduit could be used for supplying fuel to a fuel injector 50 which is fitted to the combustion chamber (cf. figure 2 ).

[0031] The present invention also relates to an automatic method for decoking pipe 20, which comprises: A first operating phase of the gas generator 12 in which oil is conveyed through line 20 to nozzle 22 for supply; a second shutdown phase of the gas generator 12 in which coke is likely to appear in at least one area of ​​line 20; a third restart phase of the gas generator 12 in which liquid is conveyed through line 30 to nozzle 22. The turbulence element(s) then generate turbulence in the oil or fuel, which is configured to dislodge and remove the coke from each area(s). The startup and subsequent operating phase contribute to dislodging and removing the small amount of coke generated in the single preceding shutdown phase.

Claims

1. An aircraft turbomachine (10), comprising a gas generator (12) comprising, along a longitudinal axis (X), at least one compressor (14), a combustion chamber (16) and at least one turbine (18), the turbomachine (10) further comprising at least one duct (20) for supplying liquid to at least one oil nozzle (22), this duct (20) comprising rectilinear portions (21a, 21b) and bent portions (21c, 21d) and comprising at least one area in which the liquid is liable to coke, characterized in that it comprises at least one turbulence element (40-48) projecting at the level of said at least one area in the duct.

2. The turbomachine (10) according to claim 1, wherein the duct (20) comprises several successive areas in which the liquid is liable to coke, at least one turbulence element (40-48) being located at each of these areas in the duct.

3. The turbomachine (10) according to claim 2, wherein the turbulence elements (40-48) are of the same type.

4. The turbomachine (10) according to claim 2, wherein the turbulence elements (40-48) are of different types.

5. The turbomachine (10) according to one of the preceding claims, wherein said or each turbulence element (40-48) is an obstacle or a guide in the form of a stud, fin, propeller, thread or twisted strip.

6. The turbomachine (10) according to one of the preceding claims, wherein said or each turbulence element (40-48) passes through all or part of the duct (20).

7. The turbomachine (10) according to one of the preceding claims, wherein the duct (20) supplies oil to said at least one nozzle (22) which is configured to lubricate at least one bearing (24) of the turbomachine.

8. A method of decoking a liquid supply duct, for use in a turbomachine (10) according to any one of the preceding claims, comprising: - a first operating phase of the gas generator (12) wherein the liquid is conveyed by the duct (20) to at least one oil nozzle (22), in order to supply it with this liquid, - a second stop phase of the gas generator (12) wherein the coke is liable to form in said at least one area of the duct (20), - a third restarting phase of the gas generator (12) wherein liquid is conveyed through the duct (20) to said oil nozzle (22), said at least one turbulence element (42-48) generating turbulences in the liquid which are configured to lift and evacuate the coke from said at least one area.