Aircraft turbine engine comprising a heat exchange system

Abstract

The invention relates to an aircraft turbine engine (1), the turbine engine (1) having a longitudinal axis (X) and comprising: - a primary oil circuit (C1) for cooling a mechanical device; - a secondary oil circuit (C2) for cooling an electronic device (16); and - a heat exchange system (20) located in a duct (V2) to be swept by a gas flow (F2), this heat exchange system (20) comprising a first cooling circuit (C21) connected to the secondary oil circuit (C2) and a second cooling circuit (C11) connected to the primary oil circuit (C1).

Description

[0001] DESCRIPTION

[0002] TITLE: AIRCRAFT TURBOMACHINE COMPRISING A HEAT EXCHANGE SYSTEM

[0003] Field of invention

[0004] The present invention relates to the general field of cooling, and its application in particular in the field of aeronautics. It relates in particular to an aircraft turbomachine comprising a heat exchange system.

[0005] Technical background

[0006] The technical background includes in particular documents US-A1 -2013 / 086909, FR-A1-3 114 352, US-A-4,696,1456, US-B2-7,908,840 and US-A1 -2020 / 332718.

[0007] A turbomachine, particularly an aircraft turbomachine, comprises various components and / or equipment that must be lubricated and / or cooled, such as rolling bearings and gears. The heat released by these components, which can be very significant depending on the power of the component and / or equipment, is transported by a fluid and evacuated to cold sources available in the aircraft.

[0008] It is known to equip the turbomachine with one or more heat exchange systems to carry out the heat exchange between the fluid (typically oil) and the cold source (air, fuel, etc.). There are even different types of heat exchange systems which are for example the fuel / oil heat exchangers generally known by the English acronym FCOC for "Fuel Cooled Oil Cooler" and the air / oil heat exchangers known by the English acronym ACOC for "Air-Cooled Oil Cooler".

[0009] FCOC heat exchangers have a dual function of heating the fuel before combustion in the turbomachine combustion chamber and cooling the oil heated by the turbomachine's heat dissipation. However, FCOC heat exchangers are not sufficient to absorb all the heat dissipation because the fuel temperature is limited for safety reasons.

[0010] Additional cooling is achieved by ACOC heat exchangers, particularly those of the surface type and known by the acronym SACOC. Surface heat exchangers are generally arranged in the secondary vein of the turbomachine and use the secondary air flow to cool the oil circulating in the turbomachine. These heat exchangers are in the form of a metal surface part allowing the passage of oil in machined channels. The secondary air flow is guided along a heat exchange matrix carried by this surface part and whose role is to increase the contact surface with the secondary air flow and to extract calories.However, SACOC heat exchangers have the disadvantage of creating additional pressure losses in the secondary vein concerned since they disrupt the air flow, which impacts the performance of the turbomachine as well as the specific fuel consumption.

[0011] The Applicant has already proposed a solution to this problem in documents FRAI-3 096 409 and FR-A1-3 096 444.

[0012] In addition, the cooling requirements of the lubricating fluid are increasing due to the increase in rotational speeds and powers involved to meet specification trends on turbomachines.

[0013] Indeed, ACOC exchangers are increasingly in demand in the future generation of engines due to the significant increase in heat dissipation, mainly due to:

[0014] - to the engines of the future which are larger, which increases the need for lubrication and cooling with oil,

[0015] - the presence of a speed reducer in new motor architectures, this reducer transmitting very high mechanical power and needing to be lubricated and cooled by oil, and

[0016] - the addition of electrical machines on board an engine for hybridization, these machines needing to be lubricated and cooled by oil.

[0017] The engine may have several oil circuits, each with a defined function, for example a first circuit for cooling the oil dedicated to lubricating and cooling the engine, a second for lubricating and cooling the motor reducer, a third for cooling the machines, etc. The oil temperature and flow rate must be controlled according to the corresponding circuit. For example, the oil used to lubricate and cool electrical machines has a different temperature range than that for engine cooling. Thus, the ACOC is preferably divided into several exchangers, each exchanger being dedicated to a given oil circuit. These different exchangers are generally distributed around the longitudinal axis of the engine

[0018] The growing need for cooling has a direct impact on the dimensions of ACOCs. Large heat exchangers are therefore required to evacuate the oil heat. In order to evacuate the oil heat, ACOCs could occupy all the available space in a vein, and thus extend all around the vein and over the entire height or radial dimension of the vein, in order to have the necessary air flow to evacuate the heat at the sizing point, which generally occurs during the takeoff phase in the case of an extremely hot day.

[0019] However, the fact that the ACOC exchangers occupy the entire radial height of the vein prevents the flow passing through the exchanger from being controlled with the solution described in documents FR-A1 -3 096 409 and FR-A1 -3 096 444.

[0020] As a result, all airflow passes through the ACOCs, and as a result, each ACOC operates with suboptimal aerothermal performance. This results in high pressure drop on the air side and leads to inefficient exchangers.

[0021] The objective of the present invention is to propose an improvement to existing technologies making it possible to optimize the efficiency of heat exchanges while avoiding pressure losses and disturbing the gas flow as little as possible.

[0022] Summary of the invention

[0023] The invention thus proposes an aircraft turbomachine, the turbomachine having a longitudinal axis and comprising:

[0024] - a gas generator extending along the axis and comprising at least one compressor, an annular combustion chamber, and at least one turbine,

[0025] - a main oil circuit for cooling mechanical equipment of the turbomachine or gas generator,

[0026] - a secondary oil circuit for cooling electronic equipment of the turbomachine or gas generator,

[0027] - a flow vein of a gas flow, which flows in the turbomachine and / or the gas generator, this vein being defined by two annular walls, respectively external and internal, which extend around each other and around the axis, and

[0028] - a heat exchange system located in said vein to be swept by at least part of said gas flow, this heat exchange system comprising a first cooling circuit connected to the secondary oil circuit and a second cooling circuit connected to the main oil circuit, characterized in that the heat exchange system comprises first and second annular heat exchange devices, which are independent and arranged axially one behind the other in the vein, the first heat exchange device comprising said first cooling circuit which is dedicated to the cooling of the secondary oil circuit, and the second heat exchange device comprising said second cooling circuit which is dedicated to the cooling of the main oil circuit,the first heat exchange device being located upstream of the second heat exchange device relative to the direction of flow of the gas flow in the vein.,

[0029] The present invention thus proposes to combine at least two annular heat exchange devices in the same annular flow vein of a gas flow. These devices are advantageously arranged in series, one behind the other, or one behind the other, which makes it possible to imitate the aerodynamic impact of these devices in the vein. These devices do not necessarily occupy the entire height of the vein and their arrangement with respect to one another, or with respect to one another, is advantageously chosen to optimize the heat exchange efficiency. In particular, the exchange device dedicated to cooling the electronic equipment is arranged upstream of the exchange device dedicated to cooling the mechanical equipment.Since the thermal power dissipated by the electronic equipment is lower than that dissipated by the mechanical equipment, the impact of the heat exchange in the first device has little impact on the temperature of the gas flow passing through the second device, which can therefore in turn ensure optimal heat exchange.

[0030] The turbomachine according to the invention may comprise one or more of the following characteristics, considered independently of one another or in combination with one another: - the devices are carried by one of the walls and extend over only part of a height of the vein, this height being measured in the radial direction in a zone of the vein in which the devices are located;

[0031] - the devices extend over at most 75%, or even at most 50%, of the height of the vein;

[0032] - the devices each comprise a heat exchange matrix and a single annular cover which is located between the walls of the vein and which covers the heat exchange matrices of the two devices, the cover comprising a first end which is located upstream of the heat exchange matrix of the first device and which has a divergent shape with respect to the gas flow, and a second end which is located downstream of the heat exchange matrix of the second device and which has a convergent shape with respect to the gas flow;

[0033] - the devices are connected to the two walls and extend over an entire height of the vein, this height being measured in the radial direction in an area of ​​the vein in which the devices are located;

[0034] - the heat exchange system comprises a third annular heat exchange device, which is independent of the first and second heat exchange devices and which is arranged downstream of the first and second heat exchange devices, the third heat exchange device comprising a third cooling circuit;

[0035] - the third device is carried by one of the walls and extends over only part of a height of the vein, this height being measured in the radial direction in an area of ​​the vein in which the third device is located;

[0036] - the first device is connected to the two walls and extends over an entire height of the vein, this height being measured in the radial direction in an area of ​​the vein in which the first device is located,

[0037] - the second device is carried by one of the walls and extends over only part of a height of the vein, this height being measured in the radial direction in an area of ​​the vein in which the second device is located, and

[0038] - the third device is carried by the other of the walls and extends over only a part of a height of the vein, this height being measured in the radial direction in an area of ​​the vein in which the third device is located; - each of the second and third devices comprises a heat exchange matrix and an annular cover which is located between the walls of the vein and which covers this heat exchange matrix, the cover comprising a first end which is located upstream of the heat exchange matrix and which has a divergent shape with respect to the gas flow, and a second end which is located downstream of the heat exchange matrix and which has a convergent shape with respect to this gas flow;

[0039] - the covers of the second and third devices are axially spaced from each other, or overlap each other in the radial direction;

[0040] - the mechanical equipment is a rolling bearing or a reducer, and the electronic equipment is a computer or an electrical machine;

[0041] - the third cooling circuit is connected to a tertiary oil circuit dedicated to the cooling of other mechanical equipment;

[0042] - the devices are axially spaced from each other or from each other;

[0043] - the first heat exchange device is of the surface type, and / or the second heat exchange device is of the surface type, and / or the third heat exchange device is of the surface type;

[0044] - the or each heat exchange device is of the SACOC or ACOC type.

[0045] The present invention also relates to a method for cooling at least one mechanical equipment and one electronic equipment in a turbomachine as described above, in which the secondary oil circuit comprises an oil having a temperature less than or equal to 90°C, and the main oil circuit, or even the tertiary oil circuit, comprises an oil having a temperature less than or equal to 160°C.

[0046] Brief description of the figures

[0047] The invention will be better understood, and other aims, details, characteristics and advantages thereof will appear more clearly on reading the detailed explanatory description which follows, of embodiments of the invention given as purely illustrative and non-limiting examples, with reference to the appended schematic drawings in which:

[0048] [Fig. 1] Figure 1 is a half schematic axial sectional view of an example of a turbomachine to which the invention applies; [Fig. 2] Figure 2 is a very schematic cross-sectional view of a heat exchange system;

[0049] [Fig. 3] Figure 3 is a very schematic view in axial section of the system of Figure 2;

[0050] [Fig. 4] Figure 4 is another very schematic view of a system similar to that of Figure 3;

[0051] [Fig. 5] Figure 5 is a schematic perspective and partial view of a heat exchange device;

[0052] [Fig. 6a-6b] Figures 6a and 6b are very schematic cross-sectional views of heat exchange systems each comprising a sectorized heat exchange device;

[0053] [Fig. 7] Figure 7 is a very schematic view in axial section of the system of Figure 6a;

[0054] [Fig. 8] Figure 8 is a very schematic axial sectional view of a turbomachine comprising a heat exchange system, according to a first embodiment of the invention;

[0055] [Fig. 9] Figure 9 is a very schematic axial sectional view of a turbomachine comprising a heat exchange system, according to a second embodiment of the invention; and

[0056] [Fig. 10] Figure 10 is a very schematic axial sectional view of a turbomachine comprising a heat exchange system, according to a third embodiment of the invention.

[0057] Detailed description of the invention

[0058] Figure 1 shows an axial sectional view of a turbomachine with longitudinal axis X to which the invention applies. The turbomachine shown is a double-flow turbomachine 1 intended to be mounted on an aircraft. Of course, the invention is not limited to this type of turbomachine.

[0059] This double flow turbomachine 1 generally comprises a gas generator 2 upstream of which a fan or fan module 3 is mounted.

[0060] In the present invention, the terms "upstream" and "downstream" are defined in relation to the circulation of gases in the turbomachine 1 and here along the longitudinal axis X. The gas generator 2 comprises a gas compressor assembly (here comprising a low pressure compressor 4a and a high pressure compressor 4b), an annular combustion chamber 5 and a turbine assembly (here comprising a high pressure turbine 6a and a low pressure turbine 6b).

[0061] Conventionally, the turbomachine 1 comprises a low pressure shaft 7 which connects the low pressure compressor 4a and the low pressure turbine 6a to form a low pressure body, and a high pressure shaft 8 which connects the high pressure compressor 4b and the high pressure turbine 6b to form a high pressure body.

[0062] The low pressure shaft 7, centered on the longitudinal axis X, here drives a fan shaft 9 by means of a speed reducer 10. Rotating guide bearings 15 also make it possible to guide the low pressure shaft 7 in rotation relative to a fixed structure or stator of the turbomachine. The high pressure shaft 8 is also guided in rotation by guide bearings (not shown).

[0063] The fan 3 is shrouded by a fan casing 11 carried by a nacelle 12 and generates a primary air flow F1 which circulates through the gas generator 2 in a primary vein V1, and a secondary air flow F2 which circulates in a secondary vein V2 around the gas generator 2.

[0064] The secondary air flow F2 is ejected by a secondary nozzle 13 terminating the nacelle while the primary air flow F1 is ejected outside the turbomachine 1 via an ejection nozzle 14 located downstream of the gas generator 2.

[0065] In the remainder of the description, the fan casing 11 and the nacelle 12 are considered as a single part.

[0066] The guide bearings 15 and the speed reducer 10 in this example configuration of the turbomachine 1 must be lubricated and / or cooled to ensure the performance of the turbomachine 1. The power generated by them is dissipated in a fluid coming from a fluid supply source installed in the turbomachine 1 and which makes it possible to lubricate and / or cool various components and / or equipment of the turbomachine 1. Of course, other equipment of the turbomachine 1 generates heat which must be extracted from its environment. This is particularly the case for electronic equipment 16 of the turbomachine 1, such as computers for example.

[0067] For this purpose, the turbomachine 1 comprises a heat exchange system 20 which makes it possible to cool the fluid intended to lubricate and / or cool these components and / or equipment. In the present example, the fluid is an oil and the cold source intended to cool the oil is a gas flow circulating in the turbomachine, in particular the secondary air flow F2.

[0068] A heat exchange system 20 comprises at least one annular heat exchange device which is located in a vein, this vein comprising two annular walls, respectively external and internal, which extend around each other and around the same axis X.

[0069] In the case of Figure 1 for example, the heat exchange system 20 of the turbomachine 1 comprises an external wall 22 formed by the fan casing 11 and / or the nacelle 12, an internal wall 23 formed by a casing of the gas generator 2, and a heat exchange device 21 which is here carried by the external wall 22 and located in the vein V2.

[0070] The heat exchange device 21 is for example of the surface type (for example of the SACOC type) and preferably of the air / oil type.

[0071] The device 21 comprises an oil circuit and a heat exchange matrix located in the vein V2 and configured to be swept by said gas flow F2. As mentioned above, the heat exchange matrix may comprise fins and / or plates and / or tubes. A matrix may be staged and comprise, for example, a stack of several layers, each of the layers comprising fins, or at least one plate or at least one tube. The fins are intended to be swept by a gas flow, and the plates or tubes are traversed, for example, by an oil circuit or comprise such an oil circuit.

[0072] Figures 2 and 3 schematically show a heat exchange system 20 of this type. It can be seen that the heat exchange device 21 of this system 20 is annular and extends continuously over 360° around the X axis.

[0073] It is also noted that it occupies only a part of the height H of the vein V2. The device 21 has a height h or radial dimension which represents only a part of the height H or radial dimension of the vein V2. These heights H, h are measured in the radial direction with respect to the axis X, in an area of ​​the vein V2 in which this device 21 is located. The height H of the vein V2 is likely to change along the axis X. One of the problems observed in a device 21 of this type is the disturbances and the pressure losses generated in the gas flow F2, which has the effect of increasing the specific and fuel consumption of the turbomachine 1. Hence the interest in optimizing the aerothermal performance of this system 20.

[0074] In the aforementioned documents, the Applicant has proposed a solution for optimizing the integration of this type of device 21 in a vein, which is illustrated in Figure 4. The idea is to slow down the speed of the gas flow passing through the device 21. Indeed, the gas flow passing through the device 21 is very turbulent. Slowing down the flow speed of the air flow at the inlet of the device 21 makes it possible to optimize its aerothermal performance and thus minimize the pressure drop for a given heat dissipation. The flow passing through the device 21 can be controlled by associating with the device 21 a divergent 24 at the inlet and a convergent 25.The divergent 24 upstream of the device 21 is configured so as to compress and slow down the flow of gas entering the device 21, and the convergent 25 arranged downstream of the device 21 is configured so as to accelerate and expand the flow of gas leaving the deviceError! Source of the reference not found.. At the inlet of the device 21, the slowing down factor is inversely proportional to the ratio of the heights h / hO, h being the aforementioned height and hO being the height at the inlet of the divergent 24. Note that the more the flow is slowed down, the more the pressure drop generated by the device 21 decreases. At the outlet of the device 21, the acceleration factor is inversely proportional to the ratio of the heights h / h3, h3 being the height at the outlet of the convergent 25.

[0075] Figure 5 illustrates in perspective a part of a heat exchange device 21. It shows the heat exchange matrix 26 which is interposed or sandwiched between a cover 27 and the wall 22, 23 which carries this device 21. The convergent 25 and the divergent 24 can be formed by ends of the cover 26, as in the example shown.

[0076] In Figure 5 and the other figures, arrows are used to schematically represent the oil circuit 28.

[0077] Figures 6a and 6b schematically show alternative embodiments of heat exchange systems 20. In the case of Figure 6a, the system 20 comprises an annular heat exchange device 21 which is sectorized and comprises two sectors each having an angular extent of approximately 180°.

[0078] In the case of Figure 6b, the system 20 comprises an annular heat exchange device 21 which is sectorized and comprises four sectors each having an angular extent of approximately 90°.

[0079] Furthermore, in these figures 6a-6b, the heat exchange device 21 extends over the entire height H of the vein and is connected to the two walls 22, 23. The height h of the device 21 is then equal to the height H of the vein (figure 7).

[0080] The present invention provides an improvement to this technology and provides several embodiments which are illustrated in Figures 8 and following.

[0081] One of the particularities of the invention is based on the fact that the heat exchange system comprises at least two independent annular heat exchange devices and that each of these devices is dedicated to the cooling of different equipment.

[0082] The turbomachine 1 which is very schematically represented by a rectangle in figure 8 and which can be compared to that of figure 1, comprises:

[0083] - a main oil circuit C1 for cooling mechanical equipment of the turbomachine 1 or the gas generator 2, this mechanical equipment being for example a reducer 10 or a bearing 15, and

[0084] - a secondary oil circuit C2 for cooling electronic equipment 16 of the turbomachine 1 or the gas generator 2.

[0085] The heat exchange system 20 of the turbomachine 1 is located in a vein V2 of the aforementioned type and is swept by at least a portion of the gas flow F2 flowing in this vein. This heat exchange system 20 comprises a first cooling circuit C21 connected to the secondary oil circuit C2 and a second cooling circuit C11 connected to the main oil circuit C1.

[0086] According to the invention, the heat exchange system 20 comprises first and second annular heat exchange devices 21, 30, which are independent and arranged axially one behind the other in the vein V2.

[0087] The first heat exchange device 21 comprises the first cooling circuit C21 and is dedicated to the cooling of the secondary oil circuit C2 and therefore to the electronic equipment 16. The second heat exchange device 30 comprises the second cooling circuit C11 and is dedicated to the cooling of the main oil circuit C1 and therefore to the mechanical equipment.

[0088] The first heat exchange device 21 is located upstream of the second heat exchange device 30 relative to the direction of flow of the gas flow F2 in the vein V2.

[0089] In the example shown, the devices 21, 30 are located on the internal wall 23 but as a variant they could be located on the external wall 22.

[0090] These devices 21, 30 are preferably of the air-oil type and for example surface type and each comprise a heat exchange matrix 26 located in the vein V2 and capped by an annular cover 27.

[0091] In the example shown, the two devices 21, 30 have the same cover 27 or share the same cover 27.

[0092] The heat exchange matrices 26 of the devices 21, 30 are axially spaced from each other and the cover 27 comprises a first end 27a located upstream of the heat exchange matrix 26 of the device 21 relative to the flow of the gas flow F2, and which has a divergent shape with respect to this gas flow F2, and a second end 27b located downstream of the heat exchange matrix 26 of the device 30 relative to the flow of the gas flow F2, and which has a convergent shape with respect to this gas flow F2.

[0093] In the example shown, the ends 27a, 27b each have a truncated or curved shape.

[0094] Each of the devices 21, 30 may comprise a single heat exchange matrix 26, or a sectored one and comprise two or more heat exchange matrices distributed around the X axis, as mentioned above.

[0095] In the example shown, the first device 21 located on the left in the drawing is an upstream device which occupies a height h in the vein of between 20 and 50% of the height H. The second device 30 located on the right in the drawing is a downstream device which occupies a height h' in the vein of between 20 and 50% of the height H', h' may be greater or less than h.

[0096] It is understood that an internal peripheral portion F2' of the air flow F2 (for example 5 to 30% of the flow rate) flowing in the vein V2 will enter the device 21 while the remainder will bypass the device 21 from the outside. This gas flow F2' will participate in the cooling of the oil in the circuit C2, then will then enter the device 30 to participate in the cooling of the oil in the circuit C1. The device 30 is thus crossed by a gas flow F2' which has already been used for cooling, which limits the impact on the remaining gas flow which bypasses the system 20. As the temperature of the oil in the circuit C2 is lower than the temperature of the oil in the circuit C1, the cooling requirement of the circuit C2 is lower than the cooling requirement of the circuit C1.This means that the power dissipated by the circuit C2 in the gas flow is relatively low and has little effect on the temperature of this gas flow which can ensure effective cooling of the oil circuit C1 in the device 30.

[0097] The second embodiment illustrated in Figure 9 differs from the first embodiment in that the devices 21, 30 extend over the entire height of the vein V2 and are therefore connected respectively to the two walls 22, 23.

[0098] The devices 21, 30 are axially spaced from each other and do not have a cover.

[0099] Each of the devices 21, 30 may comprise a single heat exchange matrix 26, or a sectored one and comprise two or more heat exchange matrices distributed around the X axis, as mentioned above.

[0100] It is understood that the entire flow of gas F2 flowing in the vein V2 will enter the device 21 and will participate in the cooling of the oil in the circuit C2, then will then enter the device 30 to participate in the cooling of the oil in the circuit C1.

[0101] The device 30 is thus crossed by a flow of gas F2 which has already been used for cooling, as mentioned above.

[0102] The third embodiment illustrated in Figure 10 differs from the first embodiment in particular by the fact that it comprises three annular heat exchange devices 21, 30, 40 which extend around the axis X and are located in the vein V2.

[0103] The first device 21 is connected to the two walls 22, 23 and extends over the entire height of the vein V2. Its height h1 is thus equal to the height H1 of the vein in this zone. This device is similar to the device 21 of Figure 9. The second device 30 is carried by one of the walls, and in particular the internal wall 23, and extends over a predetermined height h2 in the vein (of height H2 in this zone). This device 30 is similar to the device 30 of Figure 8 except that it includes its own cover 27.

[0104] The third device 40 is carried by the other of the walls, in particular the external wall 22, and extends over a predetermined height h3 in the vein (of height H3 in this zone). This device 40 comprises a third cooling circuit C31 which is dedicated to the cooling of a tertiary oil circuit C3 of another mechanical equipment - advantageously different from the mechanical equipment cooled by the primary circuit C1.

[0105] The device 30 is for example used to cool the reducer 10 and the device 40 is for example chosen to cool one or more of the bearings 15, or vice versa.

[0106] Each of the devices 30, 40 comprises a heat exchange matrix 26 and an annular cover 27, 27' which is located between the walls 22, 23 of the vein V2 and which covers this heat exchange matrix 26.

[0107] The cover 27 of the device 30 comprises a first end 27a located upstream of the heat exchange matrix 26 relative to the flow of the gas flow, and which has a divergent shape relative to this gas flow F2, and a second end 27b located downstream of the heat exchange matrix 26 relative to the flow of the gas flow, and which has a convergent shape relative to this gas flow F2.

[0108] The device 40 comprises a cover 27' which comprises a first end 27a' located upstream of the heat exchange matrix 26 relative to the flow of the gas flow, and which has a divergent shape relative to this gas flow F2, and a second end 27b' located downstream of the heat exchange matrix 26 relative to the flow of the gas flow, and which has a convergent shape relative to this gas flow F2.

[0109] The covers 27, 27' of the devices 30, 40 are axially spaced from each other, but may alternatively overlap each other in the radial direction.

[0110] It is understood that the entire gas flow F2 flowing in the vein V2 will enter the device 21 and will participate in the cooling of the oil in the circuit C2. Then, an internal peripheral part of the air flow F2 (for example 5 to 30% of the flow rate) flowing in the vein will enter the device 30 while the rest will bypass the device 30. The gas flow which enters the device 30 will participate in the cooling of the oil in the circuit C1.

[0111] A portion of the gas flow which bypasses the device 30 will then enter the device 40 to participate in cooling the oil in the circuit 3.

[0112] In the various embodiments described above, the secondary oil circuit C2 comprises an oil having a temperature less than or equal to 90°C for example. The main oil circuit C1, or even the tertiary oil circuit C3 in the case of Figure 10, comprises an oil having a temperature less than or equal to 160°C for example.

[0113] The invention brings several advantages including:

[0114] • Improved aerothermal performance of the devices: the proposed concept makes it possible to optimize the flow from an aerothermal point of view in each device. Indeed, the heat exchange system does not necessarily occupy all the available radial height, which makes it possible to install a divergent / convergent device upstream / downstream to better manage the flow in each of the exchangers, without obstructing the vein, and thus to achieve a significant slowdown of the flow passing through each device. This makes it possible to optimize the aerothermal performance of each device, to reduce pressure losses on the air side, and to have more efficient devices;

[0115] • Installing the devices on either side of the vein walls allows air to be taken at the same temperature at the inlet of these two devices, which is approximately the same as that at the vein inlet. This avoids reusing the same flow of heated air at the outlet of the first exchanger to cool the oil in the second exchanger, and thus increases the aerothermal performance of the two devices;

[0116] • The axial offset between two devices allows the vein to be cleared in the radial direction.

Claims

CLAIMS 1. Aircraft turbomachine (1), the turbomachine (1) having a longitudinal axis (X) and comprising: - a gas generator (2) extending along the axis (X) and comprising at least one compressor (4, 4b), an annular combustion chamber (5), and at least one turbine (6a, 6b), - a main oil circuit (C1) for cooling mechanical equipment of the turbomachine (1) or the gas generator (2), - a secondary oil circuit (C2) for cooling electronic equipment (16) of the turbomachine (1) or the gas generator (2), - a flow vein (V2) of a gas flow (F2), which flows in the turbomachine (1) and / or the gas generator (2), this vein (V2) being defined by two annular walls, respectively external (22) and internal (23), which extend around each other and around the axis (X), and - a heat exchange system (20) located in said vein (V2) to be swept by at least a part of said gas flow (F2), this heat exchange system (20) comprising a first cooling circuit (C21) connected to the secondary oil circuit (C2) and a second cooling circuit (C11) connected to the main oil circuit (C1), characterized in that the heat exchange system (20) comprises first and second annular heat exchange devices (21, 30), which are independent and arranged axially one behind the other in the vein (V2), the first heat exchange device (21) comprising said first cooling circuit (C21) which is dedicated to the cooling of the secondary oil circuit (C2), and the second heat exchange device (30) comprising said second cooling circuit (C21) which is dedicated to the cooling of the main oil circuit (C1),the first heat exchange device (21) being located upstream of the second heat exchange device (30) relative to the direction of flow of the gas flow (F2) in the vein (V2)., 2. Turbomachine (1) according to claim 1, characterized in that the devices (21, 30) are carried by one of the walls (22, 23) and extend over only a part of a height (H) of the vein (V2), this height being measured in the radial direction in an area of ​​the vein (V2) in which the devices (21, 30) are located.

3. Turbomachine (1) according to claim 2, characterized in that the devices (21, 30) extend over at most 75%, or even at most 50%, of the height (H) of the vein (V2).

4. Turbomachine (1) according to claim 2 or 3, characterized in that the devices (21, 30) each comprise a heat exchange matrix (26) and a single annular cover (27) which is located between the walls (22, 23) of the vein (V2) and which covers the heat exchange matrices (26) of the two devices (21, 30), the cover (27) comprising a first end (27a) which is located upstream of the heat exchange matrix (26) of the first device (21) and which has a divergent shape with respect to the gas flow (F2), and a second end (27b) which is located downstream of the heat exchange matrix (26) of the second device (30) and which has a convergent shape with respect to the gas flow (F2).

5. Turbomachine (1) according to claim 1, characterized in that the devices (21, 30) are connected to the two walls (22, 23) and extend over an entire height (H) of the vein (V2), this height being measured in the radial direction in a zone of the vein (V2) in which the devices (21, 30) are located.

6. Turbomachine (1) according to claim 1, characterized in that the heat exchange system (20) comprises a third annular heat exchange device (40), which is independent of the first and second heat exchange devices (21, 30) and which is arranged downstream of the first and second heat exchange devices (21, 30), the third heat exchange device (40) comprising a third cooling circuit (C31).

7. Turbomachine (1) according to claim 6, characterized in that the third device (40) is carried by one of the walls (22, 23) and extends over only part of a height (H) of the vein (V2), this height being measured in the radial direction in a zone of the vein (V2) in which the third device (40) is located.

8. Turbomachine (1) according to claim 7, characterized in that: - the first device (21) is connected to the two walls (22, 23) and extends over an entire height (H1) of the vein (V2), this height being measured in the radial direction in a zone of the vein (V2) in which the first device (21) is located, - the second device (30) is carried by one of the walls (22, 23) and extends over only part of a height (H2) of the vein (V2), this height being measured in the radial direction in a zone of the vein (V2) in which the second device (30) is located, and - the third device (40) is carried by the other of the walls (22, 23) and extends over only part of a height (H3) of the vein (V2), this height being measured in the radial direction in a zone of the vein (V2) in which the third device (40) is located.

9. Turbomachine (1) according to claim 8, characterized in that each of the second and third devices (30, 40) comprises a heat exchange matrix (26) and an annular cover (27, 27') which is located between the walls (22, 23) of the vein (V2) and which covers this heat exchange matrix (26), the cover (27) comprising a first end (27a) which is located upstream of the heat exchange matrix (26) and which has a divergent shape with respect to the gas flow (F2), and a second end (27b) which is located downstream of the heat exchange matrix (26) and which has a convergent shape with respect to this gas flow (F2).

10. Turbomachine (1) according to claim 9, characterized in that the covers (27, 27') of the second and third devices (30, 40) are axially spaced from each other, or overlap each other in the radial direction.

11. Turbomachine (1) according to one of the preceding claims, characterized in that the mechanical equipment is a rolling bearing (15) or a reducer (10), and the electronic equipment (16) is a computer or an electric machine.

12. Turbomachine (1) according to claim 11, dependent on one of claims 6 to 10, characterized in that the third cooling circuit (C31) is connected to a tertiary oil circuit which is dedicated to the cooling of other mechanical equipment.

13. Turbomachine (1) according to one of the preceding claims, characterized in that the devices are axially spaced from one another or from one another.

14. Turbomachine (1) according to one of the preceding claims, characterized in that the first heat exchange device is of the surface type, and / or the second heat exchange device is of the surface type, and / or the third heat exchange device is of the surface type.

15. Turbomachine (1) according to one of the preceding claims, characterized in that the or each heat exchange device is of the SACOC or ACOC type.

16. Method for cooling at least one mechanical equipment and one electronic equipment (16) in a turbomachine (1) according to one of the preceding claims, in which the secondary oil circuit (C2) comprises an oil having a temperature less than or equal to 90°C, and the main oil circuit (C1), or even the tertiary oil circuit (C3), comprises an oil having a temperature less than or equal to 160°C.

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