Tank for a turbomachine comprising a lower compartment with a negative g compatible

Abstract

The invention relates to an oil tank (40) for a turbomachine, the oil tank comprising: an enclosure for oil, the enclosure having a main axis and having walls defining a first compartment (56) and a second compartment (58), the second compartment being separated from the first compartment by a partition wall (60); a channel (62) extending from the partition wall into the first compartment; an oil inlet (66) for oil mixed with air, the oil inlet being arranged on the second compartment; an oil outlet (74) comprising a conduit (64) extending and leading into the first compartment; wherein the passage extends within the duct to ensure and thus maintain the supply of oil to the duct during a flight phase in a zero-gravity or heavy-load condition.

Description

Technical Field

[0001] The present invention relates to the field of turbine cans and more particularly to the field of oil cans for lubricating turbine components, including in particular unducted variable pitch propellers and / or variable pitch rectifiers. Background Art

[0002] Aircraft turbomachines that include at least one unducted propeller are called "open rotors" or "unducted fans". Among these turbomachines, there are turbomachines with two unducted counter-rotating propellers, called unducted dual fans (UDF), or turbomachines with a single unducted propeller and a rectifier including a plurality of stator blades (USF).

[0003] These turbines are turboprop engines, which differ from turbojets in that they use a propeller outside the nacelle (unducted) rather than an internal fan.

[0004] The propeller or propellers forming the propulsion means generally include a system for actuating the pitch of the blades of the propeller or propellers (also known as a variable pitch system). Such a system enables the propeller blades to be oriented as required by the flight phase of the aircraft (take-off, cruise, landing, etc.) so as to ensure thrust management in all flight situations of the turbomachine.

[0005] In the case of a turbine with a single unducted propeller and a rectifier, the rectifier may also include a variable pitch system to improve the performance of the turbine. Published patent document FR 3 107 319 A1 discloses an example of such a turbine.

[0006] Variable pitch systems may require a continuous supply of oil to enable actuation of the blade pitch and management of the engine thrust in all flight conditions (normal and extreme) of the engine. In the prior art, these systems are supplied by a main lubrication circuit to ensure the supply of oil to the various components of the engine (bearings, reducers, etc.) to provide lubrication and / or cooling functions. This circuit is supplied with oil by the main tank of the turbine, which comprises, among other things, an oil inlet located in the upper part and an oil outlet located in the lower part in the vertical mounting orientation, which enables the supply of oil during flight attitudes in gravity or with a positive load factor (positive G).

[0007] Although such oil tanks are completely satisfactory when the aircraft is flying in positive G flight conditions, on the other hand, these tanks no longer fully ensure the oil supply to the pitch actuation system when the aircraft is in a flight phase with zero or negative load factor (zero G or negative G), i.e. when the aircraft is maneuvering or encountering upward gusts.

[0008] In practice, zero-gravity or negative-gravity flight phases are temporary flight phases (often lasting less than 30 seconds for civil aircraft) for which the aircraft is subjected to negative accelerations (for example when the aircraft undergoes a sudden change in altitude).

[0009] For this reason, the oil contained in the main tank thus surges out and is no longer located near the outlet in the lower part, which interrupts the oil supply and causes air to flow to one or more variable pitch circuits, with harmful consequences for the operation of the turbine, which may lead to a loss of control of the aircraft.

[0010] It is possible to use tanks such as those used in combat aircraft, where negative G flight phases are frequent and necessary. However, these tanks are pressurized, which implies a significant excess weight and high additional costs, which is incompatible with a turbine including at least one unducted propeller.

[0011] Furthermore, a known solution to avoid compromising the propeller pitch actuation circuit is to ensure the oil supply in the case of negative G by a system other than the main oil tank of the turbine. However, this solution involves significant volume and mass inside the turbine and complex management of the oil delivery to the variable pitch system.

[0012] The published patent document FR 3 010 133 A1 discloses a tank comprising an inclined partition provided at its end with through holes for continuous supply of the turbine. However, the solution proposed in this document still leaves room for improvement, so that, for example, in the case of negative G flight, a greater volume of oil can be available to supply the components of the turbine, without obstructing said volume when returning to positive G. Summary of the invention

[0013] Technical issues

[0014] The present invention aims to overcome at least one of the above-mentioned disadvantages of the prior art. More specifically, the present invention aims to propose a tank whose design enables the aircraft to perform temporary flight phases under negative gravity in total safety, without increasing the weight and cost of the tank.

[0015] Technical Solution

[0016] The present invention relates to an oil tank for a turbine, the oil tank comprising:

[0017] - a capsule for oil, the capsule having a main axis and having a wall delimiting a first compartment and a second compartment, the second compartment being separated from the first compartment by a partition wall;

[0018] - a channel extending from the partition wall into the first compartment;

[0019] - an oil inlet for oil mixed with air, the oil inlet being arranged on the second compartment;

[0020] - an oil outlet comprising a duct extending and opening into the first compartment; wherein a channel extends inside the duct to ensure the oil supply to the duct during flight phases in zero or negative gravity, thereby maintaining the oil supply to the duct.

[0021] According to an advantageous embodiment of the invention, the dividing wall is inclined towards the channel relative to a vertical line perpendicular to the main axis in order to guide the oil towards said channel.

[0022] According to an advantageous embodiment of the invention, the partition wall has an inclination angle (α) with respect to a vertical line perpendicular to the main axis, which is between 10° and 60°, more preferably between 30° and 50°.

[0023] According to an advantageous embodiment of the invention, the duct comprises a distal portion which is parallel to the dividing wall or inclined at an angle of less than 20° relative to said dividing wall.

[0024] According to an advantageous embodiment of the invention, the channel is located in the center of the partition wall and the partition wall is funnel-shaped.

[0025] According to an advantageous embodiment of the invention, the distal end of the duct is divided into a funnel shape corresponding to the funnel shape of the partition wall.

[0026] According to an advantageous embodiment of the invention, the duct comprises a proximal portion which is substantially parallel to the main axis.

[0027] According to an advantageous embodiment of the invention, the distal end of the duct divides at least 40% of the total extent of said duct.

[0028] According to an advantageous embodiment of the invention, the cross section of the duct corresponds to at least 1.2 times the cross section of the channel.

[0029] According to a preferred embodiment of the invention, the channel comprises a distal end, which together with a distal part of the pipe forms a buffer volume within the pipe, the distal end of the channel and the distal part of the pipe forming a second volume outside the pipe, the distal part of the pipe together with the partition wall forming a first volume, the first volume being smaller than the second volume in the first compartment.

[0030] According to an advantageous embodiment of the invention, the dividing wall and / or the distal end of the channel further comprises at least one valve sensitive to gravity changes and / or at least one non-return valve.

[0031] The invention also relates to a turbine, comprising:

[0032] - an unducted propeller which pushes the incoming air flow, said propeller comprising a variable pitch system for actuating the pitch of the propeller blades;

[0033] - oil tanks, which are used to lubricate the components of the turbine;

[0034] Wherein, the tank comprises:

[0035] - a capsule for oil, the capsule having a main axis and having a wall delimiting a first compartment and a second compartment, the second compartment being separated from the first compartment by a partition wall;

[0036] - a channel extending from the partition wall into the first compartment;

[0037] - an oil inlet for oil mixed with air, the oil inlet being arranged on the second compartment;

[0038] an oil outlet comprising a duct extending and opening into the first compartment; wherein a channel extends inside the duct to ensure the oil supply to the duct during flight phases when the turbine is in zero or negative gravity, thereby maintaining the oil supply to the duct.

[0039] According to an advantageous embodiment of the invention, the upper oil outlet and the oil inlet to the second compartment form together with the second compartment a first closed circuit intended for lubricating and / or cooling components of the turbine engine.

[0040] According to an advantageous embodiment of the invention, the variable pitch system is a first variable pitch system, the turbine further comprises a rectifier comprising a plurality of stator blades extending from a stationary housing, the rectifier comprising a second variable pitch system, and the oil outlet is hydraulically connected to a second closed circuit comprising components of the first system and / or the second variable pitch system of the turbine.

[0041] According to an advantageous embodiment of the invention, the oil tank of the turbine is an oil tank according to one of the advantageous embodiments of the invention described above.

[0042] Advantages of the invention

[0043] The invention is particularly advantageous in that it makes it possible to guarantee the oil supply to the various components of the turbomachine, including in particular one or more variable pitch systems, while ensuring an uninterrupted supply of pure oil, without the presence of any air, to the one or more variable pitch systems during the flight phases in zero and negative gravity conditions. Thus, the hydraulic control of the turbomachine's propeller pitch actuation system can remain operational during all flight phases of the aircraft.

[0044] Advantageously, the simplicity of the structure of the oil tank of the invention enables the oil tank to ensure reliable operation. In addition, the tank is compact, which enables the overall size and mass of the turbine to be reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] [ Figure 1 ] is a schematic axial cross-sectional view of an aircraft turbine according to the invention;

[0046] [ Figure 2 ] is a schematic diagram of each closed loop connected to the oil tank of the present invention;

[0047] [ Figure 3 ] shows a cross-sectional view of an oil tank according to the present invention;

[0048] [ Figure 4 ] shows the period of flight when the vehicle is in positive gravity Figure 3 A cross-sectional view of an oil tank;

[0049] [ Figure 5 ] shows the period of flight when the vehicle is in negative gravity Figure 3 Cross-sectional view of an oil tank. DETAILED DESCRIPTION

[0050] The accompanying drawings schematically illustrate components and are not drawn to scale. In particular, some dimensions are exaggerated to facilitate reading of the drawings.

[0051] Figure 1 An axial cross-sectional view of an aircraft turbine according to the invention is schematically shown. The aircraft turbine is a so-called open rotor or unducted fan turbine, in particular an unducted single fan (USF) turbine.

[0052] In the following description, the terms "inner" and "outer" refer to the positioning relative to the axis of rotation of the turbomachine and here along the longitudinal axis X (even in Figure 1The terms "radial", "inner" and "outer" are defined relative to a radial direction perpendicular to the longitudinal axis X. Upstream and downstream refer to the flow direction of the flow in the turbine. Furthermore, elements shown in the figures that are identical or substantially identical and / or have the same function are denoted by the same reference numerals.

[0053] The turbomachine 2 generally comprises, from upstream to downstream, a first compression stage, known as the low-pressure compressor 4 , a second compression stage, known as the high-pressure compressor 6 , a combustion chamber 8 , a subsequent high-pressure turbine 9 and a low-pressure turbine 10 .

[0054] The turbomachine 2 comprises a propeller 14 arranged upstream of a separation nozzle 16 carried by an outer casing 24 and capable of dividing the air flow F into a secondary flow F2 and a main flow F1 which circulates in a main channel 18 and passes through the various aforementioned stages of the turbomachine 2 .

[0055] The main flow channel 18 is radially delimited by a radial inner wall 20 and a radial outer wall 22. The radial inner wall 20 is carried by the inner casing 12. The radial outer wall 22 is carried by the outer casing 24. The main air flow F1 enters the main flow channel 18 through the annular air inlet 17 and is discharged through a main nozzle 19 arranged downstream of the main flow channel 18. The main flow F1 can be accelerated by the main nozzle 19 to generate the reverse thrust required for the flight of the aircraft.

[0056] The turbine comprises a rotating casing 26 centred on and rotating about a longitudinal axis X. The rotating casing 26 carries the crowns of movable blades 28 forming the propeller 14. The rotating casing 26 is mounted movably relative to the inner casing 12 carrying it.

[0057] The air flow F entering the turbine passes through the blades 28 of the propeller 14 to form a secondary air flow F2. The secondary air flow circulates around the outer casing 24. Each blade 28 of the propeller 14 comprises a root 30 and an aerodynamic part extending radially outwards from the root 30, the root comprising a pivot. In practice, the root 30 is mounted to pivot about an axis A (perpendicular to X), thereby enabling the blades 28 of the propeller 14 to pivot. This pivoting is controlled by a first variable pitch system of the turbine 2.

[0058] The low-pressure compressor 4 and the low-pressure turbine 10 are mechanically connected via a low-pressure shaft 11, which drives a propeller 14 via a reducer 32, which compresses the air outside the outer casing 24 and provides most of the thrust of the turbine 2. The reducer 32 may be of planetary gear type.

[0059] The turbine 2 comprises a straightener 34 traversed by a secondary flow F2, the secondary flow being a portion of the air flow F that is pushed radially outward relative to the longitudinal axis X. The straightener 34 comprises a plurality of stator blades 36 (or blades of a stator or fixed blades) (referred to as outlet guide vanes (Outlet Guide Vane, OGV)). The stator blades 36 are regularly distributed around the longitudinal axis X and extend radially in the secondary air flow F2. The stator blades 36 are carried by a fixed structure fixed to the outer casing 24. In particular, each stator blade 36 extends radially from a foot 38, which is pivotally mounted around an axis B (perpendicular to X), so that the stator blades 36 of the straightener 34 can pivot. This pivoting is controlled by a second variable pitch system of the turbine 2.

[0060] The turbine 2 further comprises an oil tank 40 for lubricating and / or cooling the components of said turbine 2. To this end, the oil tank 40 is the main oil tank of the turbine 2 and also enables the supply of oil to the first variable pitch system and the second variable pitch system of the turbine 2. Preferably, the tank 40 is arranged in line with the outer casing 24. The structure and operation of the oil tank 40 will be described in detail later in this description.

[0061] Figure 2 are illustrations of various closed circuits connected to the oil tank of the present invention.

[0062] Reference Figure 2 , the oil tank 40 is hydraulically connected to the lubrication and cooling circuit 42 of the turbine engine, which is the first closed circuit 42 of the turbine. This circuit comprises a feed pump 43, a heat exchanger 44 and a lubrication chamber 45, which ensures lubrication of the bearings, reducers and bearings, and ensures the air / oil seal of the engine.

[0063] The circuit 42 further comprises at least one recovery pump 46 configured to recover oil from the lubrication chamber 45 and direct it to the oil tank 40. The first closed circuit 42 may correspond to a lubrication group of the turbomachine.

[0064] The oil tank 40 is also hydraulically connected to a circuit 48 for actuating the pitch of the propeller blades. To this end, the circuit 48 enables the Figure 1 The first variable pitch system of the propeller 14 supplies oil; this circuit is the second closed circuit 48 of the turbine.

[0065] The step-type actuation circuit 48 can also provide actuation to the first variable pitch system independently of the first variable pitch system or in combination with the first variable pitch system. Figure 1 The second variable pitch system of the rectifier 34 supplies oil.

[0066] The step-actuated actuation circuit 48 can provide lubrication and / or cooling functions for the variable pitch system. In this regard, the circuit 48 includes a boost pump 49 that recovers oil from the lower portion of the tank 40 to direct the oil to a heat exchanger 50 .

[0067] Preferably, in addition to the lubrication and cooling functions, the pitch actuation circuit 48 is also configured to hydraulically control a variable pitch system. In this regard, the circuit 48 comprises a pitch actuation pump 51 capable of hydraulically controlling a pitch actuation system 52, which may correspond to a first variable pitch system and / or a second variable pitch system of the turbine.

[0068] In this configuration, the stepper actuation pump 51 enables the hydraulic actuator to be actuated, resulting in Figure 1 The feet 30 and 38 pivot.

[0069] Preferably, the pitch actuation circuit 48 comprises a bypass valve 53 which enables selection between a cooling function or actuation of the pitch of the variable pitch system.

[0070] Advantageously, there is a connection 71 between the hydraulic control circuit 48 and the lubrication circuit 42 to collect any leakage from the propeller pitch actuation cylinders and to refill this oil from the inlet 66 into the tank 40 .

[0071] The circuit 48 may include an oil return (shown in phantom) to a tank, or it may be connected directly upstream of the feed pump 49 .

[0072] Figure 3 A cross-sectional view of an oil tank 40 is shown, comprising a capsule 54 for oil (the oil is not shown here to better simplify the illustration), the capsule having a main axis R which preferably corresponds to the axis intended to be Figure 1 The main direction R of the turbine 2 in the installation position is oriented vertically.

[0073] The enclosure 54 is formed by walls 54.1, 54.2, 54.3 and 54.4 which delimit a first compartment 56 and a second compartment 58 which is separated from the first compartment 56 by a partition wall 60 which comprises a channel 62 which extends into the first compartment 56 and specifically into a duct 64 which forms an oil outlet from the first compartment.

[0074] Preferably, the main axis R corresponds to the main extension direction of the enclosure 54. To this end, the main axis R defines the direction of the largest dimension of said enclosure 54.

[0075] Preferably, the main axis R of the enclosure 54 follows the direction of gravity (perpendicular to the horizontal plane). However, the main axis R may be inclined at an angle of up to or exceeding 45° relative to the direction of gravity so as to form an angle of less than 90°.

[0076] According to the direction of gravity (a force perpendicular to the horizontal plane and directed downward), the second compartment 58 is located above the first compartment 56. In this configuration, the first compartment 56 is the lower compartment 56 and the second compartment 58 is the upper compartment 58.

[0077] Alternatively, the enclosure 54 of the can 40 may have a generally oval and / or curved shape. Preferably, the enclosure 54 comprises a generally cylindrical shape.

[0078] The enclosure 54 may include a perforated baffle (not shown) which is arranged above the partition wall 60 and which enables filtering and purification of the oil before it reaches the lower compartment 56 .

[0079] In this configuration, the duct 64 extends from the bottom 54 . 3 of the enclosure 54 and opens into the lower compartment 56 .

[0080] Preferably, the channel 62 is centrally located relative to the partition wall 60 and the duct 64 is centrally located relative to the bottom 54 . 3 .

[0081] The partition wall 60 is preferably inclined at an angle of inclination α comprised between 10° and 60°, more preferably between 30° and 50°, and even more preferably equal to 45°, relative to a vertical perpendicular to the main direction R. To this end, the partition wall 60 is funnel-shaped.

[0082] Advantageously, the inclination of the partition wall 60 makes it possible to better direct the oil towards the channel 62 .

[0083] Preferably, the duct 64 comprises a distal portion 64 . 1 which is parallel to the partition wall 60 and also forms a funnel corresponding to the funnel shape of the partition wall 60 , but the distal portion 64 . 1 may be inclined at an angle less than 20° relative to said partition wall 60 .

[0084] The distal portion 64.1 of the duct 64 is greater than 20% and less than 70% of the total extent of said duct 64. Preferably, the distal portion 64.1 extends over at least 40% of the total extent of said duct 64.

[0085] The duct 64 comprises a proximal portion 64 . 2 which is substantially parallel to the main direction R. To this end, the channel 62 is coaxial with the duct 64 .

[0086] The channel 62 comprises a distal end 62.1 which may comprise a valve or non-return valve 62.2 sensitive to gravity variations. In practice, the non-return valve 62.2 enables the oil to pass to leave the channel 62 during flight phases when the aircraft is in positive gravity (G positive) conditions, but does not allow any oil to pass during flight phases when the aircraft is in zero gravity or negative gravity (G0 or G negative) conditions.

[0087] Similarly, the partition wall 60 may include at least one valve and / or at least one wing 60.1 that is sensitive to changes in gravity, and advantageously, the wing 60.1 and / or the check valve 62.2 of the channel 62 may respectively enable the oil to be accelerated back into the lower compartment 56 during a transition phase from a negative G state to a positive G state, and to limit the amount of oil going to the upper compartment 58 during another transition phase from a positive G state to a negative G state.

[0088] Preferably, the partition wall 60 comprises at least one drain port 60.2 capable of discharging air that may be contained in the lower compartment 56 during the transition phase from the negative G state to the positive G state. Advantageously, the at least one drain port 60.2 (at a lateral end of the partition wall 60) is ideally arranged to accelerate the return of the oil to the lower compartment 56.

[0089] Furthermore, the distal end 62.1 and the distal part 64.1 of the duct define a buffer volume V' inside the duct 64. The buffer volume V' is included between the lines indicated in dashed lines; these lines are perpendicular to the main direction. It should be noted that the lower dashed line (near the bottom 54.3) stops at the distal end 62.1 of the channel 62, because under negative gravity conditions, the oil stops at this level and no longer passes through the channel 62 to the upper compartment 58.

[0090] The buffer volume V' depends partly on the difference between the cross-sections of the passage 62 and the duct 64. For this reason, the larger the cross-section of the duct 64 relative to the passage 62, the larger the buffer volume V'.

[0091] In this regard, preferably, the cross section of the duct 64 corresponds to at least 1.2 times the cross section of the channel 62 and / or at most 3 times the cross section of said channel 62 .

[0092] Advantageously, the funnel shape of the distal portion 64 . 1 of the duct 64 , which is parallel to the partition wall 60 , enables the oil of the buffer volume V′ to be uniformly directed downwards, thereby accelerating its exit from the lower compartment 56 .

[0093] The distal end 62.1 of the channel 62 also delimits with the distal portion 64.1 of the duct 64 a second volume V2 situated in the lower compartment 56 and outside the duct 64. The volume V2 corresponds to the volume of oil that can be completely consumed during the negative G phase before the oil supplying the second closed circuit is exhausted.

[0094] The distal end portion 64 . 1 of the duct 64 delimits, together with the partition wall 60 , a first volume V1 within the lower compartment 56 .

[0095] In this configuration, the second volume V2 is preferably greater than the first volume V1 , so as to ensure a maximum amount of oil in the lower compartment 56 , so as to supply the variable pitch system of the turbine without interruption.

[0096] Figure 4 The diagram shows the period of flight when the aircraft is in a positive G state. Figure 3 40. For this purpose, G+ refers to positive gravity and G- refers to negative gravity.

[0097] It should be noted that the tank 40 is able to ensure a constant supply of pure oil during the G-flight phases, and each of the G-phases lasts from a fraction of a second to 45 seconds. Advantageously, the tank 40 can be dimensioned to ensure a constant supply of oil even in the case of more than 45 seconds.

[0098] In this regard, the oil tank 40 comprises an oil inlet 66 for oil mixed with air, the oil inlet being directed towards the upper compartment 58, specifically towards the oil degassing device 68 so as to be able to discharge the air 70 that may be mixed with the oil. The oil inlet is preferably from Figure 2 at least one recovery pump 46 .

[0099] The tank 40 also includes an upper oil outlet 72 that, together with the oil inlet 66 and the upper compartment 58, forms an Figure 2 The first closed loop 42.

[0100] Preferably, the upper oil outlet 72 is close to the dividing wall 60 to keep said outlet 72 supplied under all circumstances, in particular during the return to the G+ state after the G- state.

[0101] The tank 40 also includes an oil outlet 74, which includes the conduit 64. In this configuration, the oil contained in the upper compartment 58 flows directly to the second closed circuit 48 (a portion of which is partially shown). To this end, the feed pump 49 continuously draws oil, the movement of which is shown by the dashed arrows.

[0102] Figure 5 The figure shows the period of flight when the aircraft is in a negative G (G-) state. Figure 3 4 . Here, the buffer volume V' enables the supply pump 49 to directly suck the oil contained in the buffer volume V' upon switching from the G+ state to the G- state. This makes it possible to ensure the supply of the second closed circuit 48 uninterruptedly.

[0103] If all the oil contained in the buffer volume V′ is consumed, the supply can be ensured by the oil contained in the volume V2 .

[0104] exist Figure 5 In the embodiment shown in FIG. 4 , the distal end 62 . 1 has no non-return valve. In fact, the arrangement of the non-return valve is optional and advantageously enables as little oil as possible to be returned to the upper compartment at the beginning of the G-phase. Air cannot reach the feed pump 49 because the suction of oil is continuous. For this reason, an air blocking area is created at the distal end 62 . 1 during the G-phase.

[0105] Advantageously, the turbine of the invention is able to ensure continuous and safe operation of the variable pitch system of the turbine thanks to a main oil tank which makes it possible to ensure the oil supply during flight phases in zero or negative gravity, thereby supplying the variable pitch system with pure oil, without any air, in an uninterrupted supply.

Claims

1. An oil tank (40) for a turbine (2), the oil tank comprising: - a capsule (54) for oil, the capsule having a main axis (R) and having walls (54.1, 54.2, 54.3, 54.4) delimiting a first compartment (56) and a second compartment (58), the second compartment being separated from the first compartment (56) by a partition wall (60); - a channel (62) extending from the partition wall (60) into the first compartment (56); - an oil inlet (66) for oil mixed with air, said oil inlet being arranged on said second compartment (58); - an oil outlet (74) comprising a duct (64) extending and opening into the first compartment (56); It is characterized in that the channel (62) extends inside the duct (64) to ensure the oil supply to the duct (64) during the flight phases in zero gravity or negative gravity conditions, thereby maintaining the oil supply to the duct (64).

2. The oil tank (40) according to claim 1, wherein: The partition wall (60) is inclined toward the passage (62) relative to a vertical line perpendicular to the main axis (R) to guide oil toward the passage (62).

3. The oil tank (40) according to claim 2, wherein: The partition wall (60) has an inclination angle (α) relative to a vertical line perpendicular to the main axis (R), and the inclination angle is between 10° and 60°, more preferably between 30° and 50°.

4. The oil tank (40) according to claims 2 and 3, wherein: The duct (64) comprises a distal portion (64.1) which is parallel to the partition wall (60) or inclined at an angle of less than 20° relative to the partition wall (60).

5. The oil tank (40) according to any one of claims 2 to 4, wherein: The channel (62) is located at the center of the partition wall (60), and the partition wall (60) is funnel-shaped.

6. The oil tank (40) according to claim 4 and 5, wherein: The distal end portion (64.1) of the duct (64) is funnel-shaped corresponding to the funnel shape of the partition wall (60).

7. The oil tank (40) according to any one of claims 1 to 6, wherein: The conduit (64) comprises a proximal portion (64.2) which is substantially parallel to the main axis (R).

8. The oil tank (40) according to any one of claims 1 to 7, wherein: The distal portion (64.1) of the conduit (64) is at least 40% of the total extent of the conduit (64).

9. The oil tank (40) according to any one of claims 1 to 8, wherein: The cross section of the duct (64) corresponds to at least 1.2 times the cross section of the channel (62).

10. The oil tank (40) according to claims 1 to 9, wherein: The channel (62) includes a distal end (62.1), which together with the distal part (64.1) of the pipe (64) forms a buffer volume (V') in the pipe (64), the distal end (62.1) of the channel (62) and the distal part (64.1) of the pipe (64) form a second volume (V2) outside the pipe (64), and the distal part (64.1) of the pipe (64) together with the partition wall (60) forms a first volume (V1), and the first volume (V1) is smaller than the second volume (V2) in the lower compartment (56).

11. The oil tank (40) according to claims 1 to 10, wherein: The partition wall (60) and / or the distal end (62.1) of the channel (62) further comprises at least one valve (60.1) responsive to changes in gravity and / or at least one non-return valve (62.2).

12. A turbine (2), comprising: - an unducted propeller (14) which propels an incoming air flow (F), the propeller (14) comprising a variable pitch system (52) for actuating the pitch of the blades (28) of the propeller (14); - an oil tank (40) for lubricating components of the turbine (2); Characterized in that the tank (40) is a tank according to any one of claims 1 to 11.

13. The turbine (2) according to claim 12, characterized in that The upper oil outlet (72) and the oil inlet (66) leading to the second compartment (58) form, together with the second compartment (58), a first closed circuit (42) intended for lubricating and / or cooling components of the engine (3) of the turbine (2).

14. The turbine (2) according to claim 12 or 13, characterized in that The variable pitch system (52) is a first variable pitch system (52), the turbine (2) further comprising a rectifier (34) comprising a plurality of stator blades (36) extending from a stationary housing (24), the rectifier (34) comprising a second variable pitch system (52), and the oil outlet (74) is hydraulically connected to a second closed circuit (48) comprising components of the first system (52) and / or the second variable pitch system (52) of the turbine.

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