Cooling and lubrication system for an aircraft turbomachine bearing and its method of use

Abstract

A cooling and lubrication system (1) for an aircraft turbomachine bearing (30) comprising: - a bearing housing (2) defining an internal volume (V) and including an air inlet passage (8), - a supply circuit (9) for the internal volume (V) with cooling and lubricating fluid, - a venting circuit (14) configured to discharge air laden with cooling and lubricating fluid from the internal volume (V) to a separator (16), - a pilot line (10) supplied by the supply circuit (9) and leading to the venting circuit (14), the pilot line (10) including a valve controllable in an open position and in a closed position to respectively allow and prevent the admission of cooling and lubricating fluid into the venting circuit (14). Abstract figure: Figure 1

Description

Title of the invention: Cooling and lubrication system for an aircraft turbomachine bearing and its method of use. Technical field

[0001] The present invention relates to the field of aircraft turbomachinery and more specifically to a cooling and lubrication system for one or more bearings and its method of use.

[0002] In a known manner, an aircraft turbomachine extends along a longitudinal axis and propels the aircraft by means of an airflow circulating from front to back within the turbomachine during a thrust phase. The aircraft turbomachine comprises, from front to back, one or more compressors, a combustion chamber, and one or more turbines. Each turbine is rotationally connected to a compressor via a shaft extending along the longitudinal axis. The aircraft turbomachine typically comprises a low-pressure shaft, connecting a low-pressure compressor and a low-pressure turbine, and a high-pressure shaft, surrounding the low-pressure shaft and connecting a high-pressure turbine and a high-pressure compressor.

[0003] In practice, the low-pressure shaft and the high-pressure shaft are supported at the front and rear by bearings, for example, ball or roller bearings, which must be lubricated and cooled. A known method for this is to house the bearings in enclosures within which they are immersed in an oil mist. Each enclosure typically comprises a stator wall extending around the rotating shaft and the bearing, as well as seals between the stator wall and the rotating shaft, for example, one at the front and one at the rear. The oil is supplied by a supply circuit and drained by gravity. Passages, typically formed in the labyrinth-type seals, allow the admission of pressurized air, notably from the compressor, in order to confine the oil within the bearing enclosure.The air, laden with suspended oil droplets, is expelled through a degassing tube and guided to a centrifugal separator to recover the oil.

[0004] In practice, the suspended oil droplets discharged into the vent tube cause pressure losses in the vent tube, which increase the pressure in the bearing housing. This reduces the pressure differential at the seals and consequently reduces the sealing in an undesirable way. It is therefore desirable to reduce the amount of oil discharged via the vent tube. This also reduces oil consumption and thus extends the intervals between refills.

[0005] Furthermore, in the presence of high temperatures exceeding 250°C, the oil present in the degassing tube is likely to form a coke deposit on the walls, this which reduces the internal cross-section and undesirably increases pressure losses. Such a coking phenomenon is particularly likely to be observed for bearings mounted at the rear of the aircraft turbomachine whose degassing tube is mounted in a turbine casing arm crossing the air stream to join the centrifugal separator in the accessory relay box located in the nacelle surrounding the aircraft turbomachine.

[0006] It is known from patent application FR3111164A1 to use a rotating blade to scrape the coke deposit behind the centrifugal separator. This does not, however, prevent the formation of coke in the degassing tube.

[0007] The invention thus aims to limit pressure losses in the degassing tube to improve sealing in the bearing housing of an aircraft turbomachine. PRESENTATION OF THE INVENTION

[0008] The invention relates to a cooling and lubrication system for at least one aircraft turbomachine bearing comprising: • a bearing enclosure defining an internal volume in which the bearing extends, the bearing enclosure including at least one air intake passage into the internal volume, • a supply circuit configured to supply the internal volume with a cooling and lubricating fluid, and • a degassing circuit configured to evacuate air charged with cooling and lubrication fluid from the internal volume, the degassing circuit including a separator configured to extract the cooling and lubrication fluid into the air charged with cooling and lubrication fluid.

[0009] The invention is remarkable in that the cooling and lubrication system includes a pilot line supplied by the supply circuit and leading to the degassing circuit, the pilot line including a controllable valve: • in an open position, to allow the admission of cooling and lubricating fluid into the degassing circuit, and • in a closed position, to prevent the admission of cooling and lubrication fluid into the degassing circuit.

[0010] The pilot line advantageously allows for simple and practical regulation of the quantity of cooling and lubricating fluid, typically oil, that is discharged into the degassing circuit, particularly as a function of the aircraft turbomachine's operating speed. The open position of the valve is particularly suitable for high aircraft turbomachine operating speeds, because the oil drawn from The supply circuit cools the oil-laden air circulating in the degassing circuit, effectively reducing the risk of coking when the oil is exposed to high temperatures. This prevents coke deposits from forming on the walls of the degassing circuit, allowing for a large flow area with minimal pressure drop. The internal volume, sealed by pressurized air, is thus optimally sealed.

[0011] The closed position of the valve is suitable for low engine speeds of the aircraft turbomachine, where a low oil flow rate in the degassing circuit helps limit pressure losses and thus ensure good sealing within the bearing housing. Thanks to the pilot line, which provides additional oil at high engine speeds of the aircraft turbomachine, the pressurization circuit supplying the internal volume with air can advantageously be smaller than in the prior art.

[0012] According to one aspect of the invention, the cooling and lubrication system includes a passive control element for the open and closed positions of the valve. This allows for simple, practical, and inexpensive regulation of the quantity of oil in the degassing circuit.

[0013] According to one aspect of the invention, the control member is configured to control the open position of the valve when the pressure of the cooling and lubricating fluid in the supply circuit or in the pilot line upstream of the valve exceeds a predetermined threshold. This corresponds to high engine speeds. This allows the valve opening to be controlled passively according to the engine speed of the aircraft turbomachine.

[0014] According to one aspect of the invention, the pilot line extends into the bearing enclosure to reduce the bulk and quantity of piping.

[0015] According to one aspect of the invention, the pilot line opens into the internal volume, opposite an inlet of the degassing circuit. Such a pilot line is advantageously easy to integrate into the bearing housing. The outlet of the pilot line is typically equipped with a nozzle that can be mounted protruding opposite the inlet of the degassing circuit to direct the cooling and lubricating fluid to it.

[0016] According to another aspect of the invention, the pilot line extends outside the bearing enclosure so as not to increase the size of the bearing enclosure.

[0017] According to one aspect of the invention, the pilot line connects the supply circuit and the degassing circuit in parallel with the internal volume. The outlet of the pilot line, typically a nozzle, opens directly into the degassing circuit, downstream of the inlet.

[0018] According to a preferred aspect of the invention, the cooling and lubricating fluid The oil flows from upstream to downstream in the feed circuit, with the pilot line entering the feed circuit upstream of at least one heat exchanger in the feed circuit with a fuel circuit of the aircraft turbomachine. The oil drawn by the pilot line to reach the degassing circuit is thus sufficiently cool to prevent coking. Furthermore, reducing the temperature of the air-oil mixture in the degassing circuit is beneficial to the separator's efficiency, reducing oil consumption despite the increased oil flow rate that the separator must process.

[0019] According to one aspect of the invention, the pilot line enters the degassing circuit at a distance from the inlet of the degassing circuit less than 50 mm, and preferably greater than 5 mm. This makes it possible to limit pressure losses right from the inlet of the degassing circuit.

[0020] According to one aspect of the invention, the pilot line includes a nozzle configured to vaporize the cooling and lubricating fluid supplying the degassing circuit. This allows the oil to be injected in the form of droplets into the degassing circuit.

[0021] The invention also relates to an aircraft turbomachine comprising: • an air stream extending along a longitudinal axis oriented from front to back in the direction of airflow during a thrust phase of the aircraft turbomachine, • at least one turbine, and • at least one cooling and lubrication system as described above extending behind the turbine.

[0022] In such a cooling and lubrication system, the degassing circuit is more likely to be exposed to high temperatures. The invention advantageously makes it possible to effectively reduce the risk of coking in this circuit.

[0023] The invention also relates to an aircraft turbomachine comprising: • an air stream extending along a longitudinal axis oriented from front to back in the direction of airflow during a thrust phase of the aircraft turbomachine, • at least one turbine and at least one arm extending radially in the air stream behind the turbine, • at least one cooling and lubrication system as described above, with the degassing circuit passing through the arm.

[0024] In such a cooling and lubrication system, the degassing circuit is more likely to be exposed to high temperatures. The invention advantageously makes it possible to effectively reduce the risk of coking in this circuit.

[0025] The invention also relates to a method of using a cooling system degassing and lubrication as described above, in which the valve is initially in the closed position to prohibit the admission of the cooling and lubrication fluid into the degassing circuit, the operating method consisting of controlling the open position of the valve, to permit the admission of the cooling and lubrication fluid into the degassing circuit.

[0026] According to one aspect of the invention, the method of use also consists, when the valve is in the open position of the valve to allow the admission of the cooling and lubricating fluid into the degassing circuit, of commanding the closed position to prohibit the admission of the cooling and lubricating fluid into the degassing circuit. PRESENTATION OF THE FIGURES

[0027] The invention will be better understood upon reading the following description, given by way of example, and referring to the following figures, given by way of non-limiting examples, in which identical references are given to similar objects.

[0028] Fig. 1 is a schematic longitudinal sectional representation of an aircraft turbomachine comprising a bearing cooling and lubrication system according to one embodiment of the invention.

[0029] Fig. 2 is a schematic representation of the cooling and lubrication system of Fig. 1.

[0030] Fig. 3 is a schematic representation of the pilot line of the cooling and lubrication system of Fig. 2 with the valve in an open position.

[0031] Fig. 4 is a schematic representation of the pilot line of the cooling and lubrication system of Fig. 2 with the valve in a closed position.

[0032] The [Fig.5] is a schematic representation of the pilot line of the cooling and lubrication system with a pilot line according to another embodiment of the invention.

[0033] Fig. 6 is a schematic representation of the pilot line of the cooling and lubrication system with a pilot line according to another embodiment of the invention.

[0034] Fig. 7 is a schematic longitudinal sectional representation of an aircraft turbomachine comprising a bearing cooling and lubrication system according to another embodiment of the invention.

[0035] It should be noted that the figures set out the invention in detail to implement the invention, said figures being of course able to serve to better define the invention where appropriate. DETAILED DESCRIPTION OF THE INVENTION

[0036] With reference to [Fig.1], the invention relates to an aircraft turbomachine 30 comprising a cooling and lubrication system 1 for one or more bearings 3. The aircraft turbomachine 30 extends conventionally along a longitudinal axis X and allows the aircraft to be moved by means of an airflow circulating from front to back in the turbomachine 30 during a thrust phase. The aircraft turbomachine 30 typically comprises, from front to back, one or more compressors 31, 32, a combustion chamber, and one or more turbines 33, 34. Each turbine 33, 34 is rotationally coupled to a compressor 31, 32 via a shaft 5, 6 extending along the longitudinal axis X. In this example, the aircraft turbomachine 30 comprises a low-pressure shaft 5, connecting a low-pressure compressor 31 and a low-pressure turbine 34, and a high-pressure shaft 6, surrounding the low-pressure shaft 5 and connecting a high-pressure turbine 33 and a high-pressure compressor 32.The low-pressure shaft 5 and the high-pressure shaft 6 are supported at the front and rear by bearings 3, for example, of the ball or roller bearing type. Only one bearing 3 at the rear of the aircraft turbomachine 30 is shown in [Fig. 1], but the invention applies to any bearing 3 supporting any shaft 5, 6 of the aircraft turbomachine 30. The invention also applies to several adjacent bearings 3.

[0037] According to the invention and with reference to Figures 1 and 2, the cooling and lubrication system 1 comprises: • a level 2 enclosure delimiting an internal volume V in which level 3 (or several neighboring levels 3) extends and comprising one or more air intake passages 8 A into the internal volume V, • a supply circuit 9 configured to supply the internal volume V with a cooling and lubricating fluid H, typically oil, • a degassing circuit 14 configured to evacuate the oil-laden air AH from the internal volume V, and comprising a separator 16 configured to extract the oil H from the oil-laden air AH, • a pilot line 10 supplied by the supply circuit 9 and leading to the degassing circuit 14, the pilot line 10 comprising a controllable valve 11, in an open position O, to allow the admission of oil H into the degassing circuit 14, and in a closed position F, to prohibit the admission of oil H into the degassing circuit 14.

[0038] The integration of a pilot line 10 equipped with a valve 11 between the supply circuit 9 and the degassing circuit 14 advantageously allows the quantity of oil H discharged into the degassing circuit 14 to be regulated in a simple and This is particularly useful depending on the operating conditions of the aircraft turbomachine 30. The open position O of the valve 11 is especially suitable for high operating conditions of the aircraft turbomachine 30, because the oil H drawn from the supply circuit 9 cools the oil-laden air AH circulating in the degassing circuit 14, thus effectively reducing the risk of coking when the oil H is exposed to high temperatures, particularly above 250°C, preferably 300°C. This prevents coke deposits from forming on the walls of the degassing circuit 14, allowing for a large flow area with minimal pressure drop. The sealing of the internal volume V, ensured by the pressurized air A, is therefore optimal.

[0039] The closed position F of the valve 11 is suitable for the low speeds of the aircraft turbomachine 30, for which a low flow of oil H in the degassing circuit 14 helps to limit pressure losses and thus ensure good sealing in the bearing enclosure 2. Thanks to the pilot line 10 which provides additional oil H during the high speeds of the aircraft turbomachine 30, the pressurization circuit supplying the internal volume with air can advantageously be undersized compared to the prior art.

[0040] In a conventional manner and as illustrated in [Fig.2], the bearing housing 2 comprises a stator wall 4 extending around the shaft 5, 6 of the aircraft turbomachine 30 and the bearing 3, delimiting the internal volume V. The bearing 3 comprises a stator support element integral with the stator wall 4 and a rotor guide element driven in rotation by the shaft 5, 6. The bearing housing 2 also comprises seals 7, in particular of a dynamic type, typically of the labyrinth type, between the stator wall 4 and the shaft 5, 6, for example one at the front and one at the rear as illustrated in [Fig.2]. The air intake passages 8 A are typically formed in the labyrinth-type seals 7 and allow pressurized air A to be admitted, notably taken from the compressor 31, 32, in order to confine the oil H in the bearing enclosure 2.

[0041] With further reference to [Fig. 2], the oil supply circuit 9 conventionally comprises, from upstream to downstream in the direction of oil flow, a reservoir 20, a supply pump 21, preferably a filter (not shown), one or more air / oil H or oil H / fuel type heat exchangers, and an outlet 24 typically equipped with a nozzle. The nozzle supplies the internal volume V with oil H. In this example, a primary oil H / fuel type heat exchanger (“Fuel Cooled Oil Cooler FCOC”) and a secondary oil H / fuel type heat exchanger 23 are shown from upstream to downstream. These heat exchangers 22 and 23 are optional, and it is also possible to have a heat exchanger 22 without the presence of a heat exchanger 23. When present, the oil / fuel type heat exchanger 23 is preferably dedicated to cooling the fuel by oil under certain conditions. In this case, it will be designated OCFC for "Oil Cooled Fuel Cooler," which implies that the oil is then heated by heat exchange with the warmer fuel.

[0042] Still with reference to [Fig. 2], the cooling and lubrication system 1 also conventionally includes a drain circuit 17 configured to drain by gravity the oil H accumulated against the stator wall 4. The drain circuit 17 conventionally includes, from upstream to downstream in the direction of flow of the oil H, a pump (not shown) and a separator 18 adapted to remove the air A contained in the oil H and known to those skilled in the art as an "oil deaerator." The separator 18 is for example located at the inlet of the tank 20 for the return of the oil H. The oil H returned to the tank 20 is then reinjected into the supply circuit 9 via the supply pump 21, while the air A is evacuated outside the aircraft turbomachine 30..

[0043] With further reference to [Fig. 2], the degassing circuit 14 allows the oil-laden air AH to be evacuated from the internal volume V. The degassing circuit 14 includes a separator 16 adapted to extract the oil droplets H contained in the air and known to those skilled in the art as an "air oil separator". The separator 16 of the degassing circuit 14 is preferably of the centrifugal type and known to those skilled in the art as a "rotary oil separator".

[0044] In the example of [Fig. 1], the separator 16 of the degassing circuit 14 is mounted in the nacelle 35 surrounding the aircraft turbomachine 30 and is driven in rotation by an accessory gearbox 36 (AGB). In this example, to convey the oil-laden air AH to the separator 16, the degassing circuit 14 extends into a turbine casing arm 37 extending radially in the air stream 38 behind the low-pressure turbine 34. Due to its location in the air stream 38, such a turbine casing arm 37 is likely to be exposed to high temperatures, and the integration of a pilot line 10 according to the invention is particularly advantageous for preventing coking.

[0045] Figure 7 illustrates another preferred embodiment of the invention, which differs from Figure 1 in that the separator 16 is mounted rotationally fixed to the low-pressure shaft 5, in this example behind the bearing 3. The degassing circuit 14 extends in this example behind the low-pressure turbine 34, specifically within the low-pressure shaft 5. Such an arrangement is known to those skilled in the art as a "center vent tube" and is described, for example, in patent application FR2929325A1. The invention is also advantageous for such an arrangement, which may expose the degassing circuit 14 to high temperatures.

[0046] With reference to [Fig. 2] and as described previously, the pilot line 10 is supplied at the inlet by the supply circuit 9 and has an outlet to the degassing circuit 14. The pilot line 10 allows, in practice, a portion of oil H, initially intended to supply the internal volume V, to be injected directly into the degassing circuit 14, preferably by means of a nozzle 13 positioned at the outlet of the pilot line 10.

[0047] In this example, the pilot line 10 connects the supply circuit 9 and the degassing circuit 14. Also in this example, the pilot line 10 is positioned outside the internal volume V. The pilot line 10 thus opens into the supply circuit 9 upstream of the outlet 24 in the internal volume V.

[0048] Preferably, as illustrated in Figures 2 and 3, the pilot line 10 opens into the supply circuit 9 downstream of the main heat exchanger 22, and preferably upstream of the secondary heat exchanger 23, i.e., at the coldest point of the oil H, since the oil H, passing subsequently through the secondary heat exchanger 23, designated OCFC, can be heated by the fuel. In this way, the extracted oil H efficiently cools the oil-laden air AH in the degassing circuit 14. Reducing the temperature of the air-oil mixture in the degassing circuit 14 is beneficial to the efficiency of the separator 16, reducing oil H consumption despite the increased oil flow rate that the separator 16 has to process.

[0049] Continuing with the example in Figures 2 and 3, the pilot line 10 preferably terminates upstream of the inlet 15 of the degassing circuit 14, preferably at a distance d less than 50 mm and greater than 5 mm. This reduces pressure losses throughout the degassing circuit 14.

[0050] With reference to Figures 2 to 4, the valve 11 is mounted on the pilot line 10 and allows the circulation of oil H in the open position O shown in [Fig. 3], and prevents the circulation of oil H in the closed position F shown in [Fig. 4]. The valve 11 preferably has only two positions, namely the open position O and the closed position F.

[0051] With reference to Figures 3 and 4, the valve 11 is preferably of the spool type and controlled by a control element 12, typically a return element such as a spring. Such a valve 11 is passively controlled by the pressure P of the oil H in the supply circuit 9 or the pilot line 10 upstream of the valve 11. When the pressure P of the oil H in the supply circuit 9 is greater than a predetermined threshold S, corresponding to a low speed of the aircraft turbine 30, the control element 12 moves the valve 11 to the open position O. When the pressure P of the oil H in the supply circuit 9 is less than the predetermined threshold S, corresponding to a high speed of the aircraft turbine 30, the control element 12 moves the valve 11 to the closed position F.The pressure P of the oil H in the supply circuit 9 is advantageously related to the speed of the aircraft turbomachine 30 because the supply pump 21 of the supply circuit 9 is typically driven in rotation by . A shaft 5, 6 of the aircraft turbomachine 30. The threshold S is judiciously chosen according to the cooling requirements. Such a passive valve architecture 11 is also simple, practical and inexpensive.

[0052] Figure 5 represents another embodiment of the invention differing from Figure 2 in that the pilot line 10 is positioned in the bearing housing 2 and connects the supply circuit 9 and the degassing circuit 14. In this example, the pilot line 10 opens upstream of the outlet 24 of the supply circuit 9 and downstream of the inlet 15 of the degassing circuit 14. As before, the pilot line 10 allows a portion of the oil H, initially intended to supply the internal volume V, to be drawn and injected directly into the degassing circuit 14. Such an arrangement reduces the overall size and the amount of piping required.

[0053] Figure 6 represents another embodiment of the invention differing from Figure 5 in that the pilot line 10 opens into the internal volume V opposite the inlet 15 of the degassing circuit 14. Such a pilot line 10 is simple and practical to integrate into the bearing housing 2, the nozzle 13 being able to be surface-mounted. Preferably, the distance d between the outlet of the pilot line 10 and the inlet 15 of the degassing circuit 14 is less than 50 mm and preferably greater than 5 mm. This allows the oil H from the pilot line 10 to be efficiently directed into the degassing circuit 14.

[0054] The invention also relates to a method of using the cooling and lubrication system 1, in which the valve 11 is initially in the closed position F illustrated in [Fig.4] prohibiting the circulation of the oil H. The method of use includes a step of controlling the open position O of the valve 11 illustrated in [Fig.3] allowing the circulation of the oil H.

[0055] Preferably, the control member 12 is of the passive type and maintains the closed position F as long as the oil pressure P H is below the predetermined threshold S, corresponding to a low speed of the aircraft turbomachine 30. This makes it possible to limit the quantity of oil in the degassing circuit 14 and thus to reduce pressure losses for better sealing of the bearing enclosure 2 at low speed.

[0056] When the pressure P of the oil H becomes greater than the predetermined threshold S, corresponding to a high speed of the aircraft turbomachine 30, the control member 12 moves the valve 11 to the open position O. This allows cold oil H to be injected into the degassing circuit 14 to avoid the occurrence of coking at high speed which would reduce the cross-section of the degassing circuit 14 in the medium term.

[0057] Preferably, when the pressure P of the oil H falls below the predetermined threshold S, the control member 12 moves the valve 11 back into the closed position F. The invention thus makes it possible to regulate the quantity of oil H in the degassing circuit 14 in a simple and practical way to maintain low losses of low-speed loads and protection against coking at high speed of the aircraft turbomachine 30. The invention thus makes it possible to decouple the need for cooling of the degassing circuit 14 at high speed and that of pressurization of the bearing enclosure 2 at low speed.

Claims

Demands

1. Cooling and lubrication system (1) for at least one aircraft turbomachine bearing (30) comprising: • a bearing enclosure (2) delimiting an internal volume (V) in which the bearing (3) extends, the bearing enclosure (2) comprising at least one air intake passage (8) (A) into the internal volume (V), • a supply circuit (9) configured to supply the internal volume (V) with a cooling and lubrication fluid (H), • a venting circuit (14) configured to vent the air laden with cooling and lubrication fluid (AH) from the internal volume (V), the venting circuit (14) comprising a separator (16) configured to extract the cooling and lubrication fluid (H) into the air laden with cooling and lubrication fluid (AH),• the cooling and lubrication system (1) being characterized in that it comprises a pilot line (10) supplied by the supply circuit (9) and leading to the degassing circuit (14), the pilot line (10) comprising a valve (11) controllable in an open position (0), to allow the admission of the cooling and lubrication fluid (H) into the degassing circuit (14), and in a closed position (F), to prohibit the admission of the cooling and lubrication fluid (H) into the degassing circuit (14).

2. Cooling and lubrication system (1) according to claim 1, comprising a passive type control element (12) for the open position (0) and the closed position (F) of the valve (11).

3. Cooling and lubrication system (1) according to claim 2, wherein the control member (12) is configured to control the open position (0) of the valve (11) when the pressure (P) of the cooling and lubrication fluid (H) in the supply circuit (9) or in the pilot line (10) upstream of the valve (11) is greater than a predetermined threshold (S).

4. Cooling and lubrication system (1) according to any one of claims 1 to 3, wherein the pilot line (10) extends into the bearing housing (2).

5. Cooling and lubrication system (1) according to claim 4, wherein the pilot line (10) opens into the internal volume (V), opposite an inlet (15) of the degassing circuit (14).

6. Cooling and lubrication system (1) according to any one of claims 1 to 3, wherein the pilot line (10) extends out of the bearing enclosure (2).

7. Cooling and lubrication system (1) according to any one of claims 1 to 4 and 6, wherein the pilot line (10) connects the supply circuit (9) and the degassing circuit (14) in parallel with the internal volume (V).

8. Cooling and lubrication system (1) according to any one of claims 1 to 7, wherein the pilot line (10) includes a nozzle (13) configured to vaporize the cooling and lubrication fluid (H) supplying the degassing circuit (14).

9. Aircraft turbomachine (30) comprising: • an air duct (38) extending along a longitudinal axis (X) oriented from front to back in the direction of airflow during a thrust phase of the aircraft turbomachine (30), • at least one turbine (33, 34) and at least one arm (37) extending radially in the air duct (38) behind the turbine (33, 34), • at least one cooling and lubrication system (1) according to any one of claims 1 to 8, the degassing circuit (14) passing through the arm (37).

10. A method of using a cooling and lubrication system (1) according to any one of claims 1 to 8, wherein the valve (11) is initially in the closed position (F) to prohibit the admission of the cooling and lubrication fluid (H) into the degassing circuit (14), the method of use consisting of controlling the open position (O) of the valve (11), to permit the admission of the cooling and lubrication fluid (H) into the degassing circuit (14).

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