Turbomachine comprising a heat exchanger between a fuel circuit and two lubricant circuits
Patent Information
- Application Number
- EP2023720918
- Authority / Receiving Office
- EP · EP
- Patent Type
- Applications
- Current Assignee / Owner
- Priority Date
- 2022-05-05
- Filing Date
- 2023-05-03
- Publication Date
- 2025-03-12
AI Technical Summary
Turbomachines face challenges in efficiently managing fluid cooling, as fuel becomes less abundant and outside air may be insufficient as a cold source, particularly during certain flight conditions, necessitating improved cooling management.
A turbomachine design incorporating a heat exchanger with a fuel circuit and two lubricant circuits, where the conduits and channels are in thermal contact, allowing for parallel flow directions and various configurations to optimize heat exchange, including circular or polygonal profiles, and forming a honeycomb structure to distribute heat exchange surfaces effectively.
This design enhances fluid cooling management by allowing for efficient heat exchange between fuel and lubricant flows, reducing manufacturing costs and size, and enabling the use of available cold sources to cool lubricant circuits, adapting to different flight conditions.
Smart Images
Figure 1.1
Abstract
Description
[0001] Turbomachine with heat exchanger between a fuel circuit and two lubricant circuits
[0002] FIELD OF THE INVENTION
[0003] The invention relates to the cooling of fluids in a turbomachine.
[0004] STATE OF THE ART
[0005] In turbomachines, certain fluids, such as engine oil or generator oil, must be cooled. The turbomachine's fuel can be used as a cooling source. As engines consume less and less fuel, fuel is becoming increasingly scarce, so another cooling source may become necessary. It is possible to use outside air, but this second cooling source may be insufficient for certain flight conditions. There is therefore a need for better fluid cooling management in turbomachines.
[0006] STATEMENT OF THE INVENTION
[0007] One aim of the invention is to propose a turbomachine which allows better management of fluid cooling.
[0008] The aim is achieved within the scope of the present invention by means of a turbomachine comprising a heat exchanger, a first circuit of a first fluid, the first circuit comprising two in the heat exchanger, a second circuit of a second fluid and a third circuit of a third fluid, each of the second circuit and the third circuit comprising a channel in the heat exchanger, each channel being contiguous to one of the conduits so as to be in thermal contact with one of the conduits, the channels being contiguous to each other so as to be in thermal contact with each other, the heat exchanger comprising a section in which the conduits and the channels are locally parallel to each other.
[0009] Such a system / method is advantageously and optionally supplemented by the following different characteristics taken alone or in combination:
[0010] - the first fluid is a fuel, the second fluid and the third fluid are lubricants;
[0011] - a high-pressure body, a high-pressure electric generator driven by a shaft of the high-pressure body, a low-pressure body and a low-pressure electric generator driven by a shaft of the low-pressure body, the lubricant circuits being an oil circuit of the high-pressure electric generator and an oil circuit of the low-pressure electric generator;
[0012] - each conduit is contiguous to one of the channels so as to be in thermal contact with one of the channels;
[0013] - the heat exchanger is configured so that fuel flows in the conduits in a direction opposite to a direction of flow of the lubricants in the channels;
[0014] - the heat exchanger is configured so that fuel flows in one of the conduits in a direction opposite to a direction of flow of fuel in the other of the conduits;
[0015] - the conduits and channels have circular walls with the same center in section;
[0016] - the conduits and channels each have a polygonal profile in section, the profiles of the channels and conduits having the same number of sides;
[0017] - the fuel circuit comprises a plurality of conduits in the heat exchanger and each lubricant circuit comprises a plurality of channels in the heat exchanger, the conduits and the channels forming a honeycomb structure, the exchanger being configured so that two channels of the same lubricant circuit are not contiguous and two conduits are not contiguous
[0018] The invention also relates to an aircraft comprising a turbomachine as just described.
[0019] The invention finally relates to a method of heat exchange in a turbomachine comprising a step of generating two first flows of a first fluid, a step of generating a second flow of a second fluid and a third flow of a third fluid, the second flow and the third flow being in thermal contact with each other, the first two flows, the second flow and the third flow flowing in flow directions locally parallel to each other, each of the second flow and the third flow being in thermal contact with one of the first two flows.
[0020] Such a method is advantageously and optionally supplemented by the following characteristic: the first fluid is a fuel, the second fluid and the third fluid are lubricants. DESCRIPTION OF THE FIGURES
[0021] Other characteristics and advantages of the invention will emerge from the following description, which is purely illustrative and non-limiting, and must be read in conjunction with the appended drawings in which:
[0022] - figure 1 is a schematic representation of a turbomachine;
[0023] - Figure 2 is a schematic representation of a heat exchanger according to one embodiment of the invention; and
[0024] - figures 3 and 4 are schematic sections of a heat exchanger according to two embodiments of the invention.
[0025] DETAILED DESCRIPTION OF THE INVENTION
[0026] Turbomachine - General presentation
[0027] With reference to Figure 1, a turbomachine is shown schematically, more specifically a double-flow axial turbojet 1. The turbojet 1 illustrated extends along an axis A and successively comprises, in the direction of flow of the gases in the turbomachine, a fan 2, a compression section which may comprise a low-pressure compressor 3 and a high-pressure compressor 4, a combustion chamber 5, and a turbine section which may comprise a high-pressure turbine 6, a low-pressure turbine 7 and an exhaust nozzle.
[0028] The blower 2 and the low pressure compressor 3 are driven in rotation by the low pressure turbine 7 via a first transmission shaft 9, while the high pressure compressor 4 is driven in rotation by the high pressure turbine 6 via a second transmission shaft 10.
[0029] In operation, a flow of air compressed by the low and high pressure compressors 3 and 4 feeds combustion in the combustion chamber 5, the expansion of the combustion gases of which drives the high and low pressure turbines 6, 7. The air propelled by the fan 2 and the combustion gases exiting the turbojet engine 1 through an exhaust nozzle downstream of the turbines 6, 7 exert a reaction thrust on the turbojet engine 1 and, through it, on a vehicle or machine such as an aircraft (not shown).
[0030] In relation to Figure 2, the turbomachine 1 comprises a heat exchanger 11 configured to ensure heat exchanges between different fluid circuits involved in the operation of the turbomachine.
[0031] The turbomachine comprises a first circuit 13 of a first fluid which passes through the heat exchanger 11.
[0032] More precisely, the first circuit comprises two conduits 31, 33 in the heat exchanger.
[0033] In a section of the heat exchanger, or even in the entire heat exchanger, the two ducts are locally parallel. This means that the ducts are:
[0034] - straight and parallel, or
[0035] - curvilinear and that for each first section of a conduit defining a first rectilinear flow direction, the second conduit comprises a second section which is closest to the first section, the second section defining a second rectilinear flow direction parallel to the first direction.
[0036] For example, the two conduits 31, 33 are rectilinear and extend parallel to a direction A, so that a flow of fuel which passes through the conduits 31, 33 flows parallel to the direction A.
[0037] The first circuit may for example be a fuel circuit 13 which notably comprises a fuel circulation system and a fuel metering system for supplying the combustion chamber.
[0038] Figure 2 illustrates the case of a fuel circuit 13 which is normally an open circuit. Such a circuit is in contact with a tank 21 which is most often located outside the turbomachine, for example in a wing of the aircraft. The fuel circuit 13 may comprise a pumping system 23 (or circulation system) configured to suck fuel from the tank into the turbomachine and circulate it to the heat exchanger 11.
[0039] The fuel circuit may also include a metering system 25 configured to regulate the flow of fuel sent to the combustion chamber 27.
[0040] The first circuit can also be a loop of a supercritical CO2 circuit, a heat pump loop, a dihydrogen circuit, a heat transfer fluid circuit, etc.
[0041] The turbomachine also comprises a second circuit 15 of a second fluid and a third circuit 17 of a third fluid.
[0042] Each of the second circuit and the third circuit passes through the heat exchanger 11. More precisely, each comprises a channel 51, 71 in the heat exchanger. In the section of the heat exchanger, or even in the entire heat exchanger, the two channels 51, 71 are locally parallel.
[0043] The second circuit 15 and the third circuit 17 may for example be two lubricant circuits 15, 17. Each comprises in particular a reservoir and a system for circulating the lubricant. Alternatively, the lubricant circuits 15 and 17 may constitute separate sections of a single overall circuit of the same lubricant, for example parallel sections which have the same inlet and the same outlet.
[0044] In a turbomachine comprising a fan speed reducer, the lubricant circuits may in particular be the engine oil circuit and the reducer oil circuit.
[0045] In a turbomachine comprising a high-pressure body and a low-pressure body as well as a high-pressure electric generator driven by the first transmission shaft 10 of the high-pressure body and a low-pressure electric generator driven by the second transmission shaft 9 of the low-pressure body, the lubricant circuits may in particular be the oil circuit of the high-pressure electric generator and the oil circuit of the low-pressure electric generator. Each of these electric generators produces electrical energy from the rotational movement of the shaft by which it is driven. Each of these generators requires a lubrication circuit which needs to be cooled.
[0046] In a turbomachine comprising a speed reducer of a fan as well as a high-pressure body, a low-pressure body, a high-pressure electric generator driven by the shaft of the high-pressure body and a low-pressure electric generator driven by the shaft of the low-pressure body, the lubricant circuits can be chosen from the engine oil circuit, the reducer oil circuit, the high-pressure electric generator oil circuit and the low-pressure electric generator oil circuit.
[0047] The second circuit or the third circuit can also be a loop of a supercritical CO2 circuit, a heat pump loop, a dihydrogen circuit, a heat transfer fluid circuit, etc.
[0048] The conduits 31, 33 and the channels 51, 71 are locally parallel to each other in the section of the heat exchanger, or even throughout the heat exchanger.
[0049] In particular, it may be preferable for the ducts and channels to be curvilinear so as to limit the size of the heat exchanger or so as to adapt the shape of the heat exchanger to constraints linked to the direct environment of the exchanger or constraints linked to the installation of the heat exchanger in the turbomachine. The heat exchanger 11 is configured to put each channel in thermal contact with one of the ducts and the two channels between them. Each channel 51, 71 is contiguous to one of the ducts 31, 33 so as to be in thermal contact with one of the ducts 31, 33.
[0050] The channels 51, 71 are contiguous to each other so as to be in thermal contact with each other.
[0051] The proximity of the contiguous channels or conduits and the material of the exchanger which separates them allows heat exchanges to take place between fuel flows / lubricant flows and between lubricant flows.
[0052] By allowing heat exchange between two independent lubricant circuits, a single heat exchanger can be used instead of two. This reduces manufacturing costs, the mass of the turbomachine, and its overall size.
[0053] Furthermore, depending on the flight point, it is possible to use one of the flows from the second circuit or the third circuit as a cold source.
[0054] Optionally, each conduit 31, 33 is also contiguous to one of the channels 51, 71 so as to be in thermal contact with this channel.
[0055] The heat exchanger 11 can be adapted according to different fluid circulation configurations.
[0056] In a first variant, the exchanger 11 is configured so that fuel flows in the conduits 31, 33 in a direction opposite to a direction of flow of the lubricants in the channels 51, 71. In this first variant:
[0057] - the fuel flows through both pipes in one and the same first direction, and
[0058] - the lubricants flow through both channels in a single second direction opposite to the first direction.
[0059] In a second variant, the heat exchanger 11 is configured so that fuel flows in one of the conduits in a direction opposite to a direction of flow of the fuel in the other of the conduits.
[0060] The fuel flows through the pipes in opposite directions. In this second variant:
[0061] - lubricants can flow through both channels in one direction, or
[0062] - lubricant can flow through one of the two channels in a first direction and lubricant can flow through the other of the two channels in a second direction opposite to the first direction.
[0063] Other variants relating to the directions of flow circulation in the exchanger are conceivable. Generally speaking, the relative circulation of the flows is defined according to the powers to be exchanged between them. For example, if it is most often necessary to ensure a greater heat exchange between a first flow of lubricant and the fuel flow than between the second flow of lubricant and the fuel flow, it is possible to place the first flow of lubricant in countercurrent to the fuel flows and the second flow of lubricant. In this case:
[0064] - the fuel flows through both pipes in one and the same first direction,
[0065] - the first flow of lubricant flows through one of the two channels in a second direction opposite to the first direction, and
[0066] - the second flow of lubricant flows through the other of the two channels in the same first direction.
[0067] Shapes of ducts and channels
[0068] The contiguity between two channels or conduits can be achieved in different ways.
[0069] In a first embodiment, in relation to FIG. 3, the conduits 31, 33 and the channels 51, 71 have circular walls with the same center in section.
[0070] The expression "in section" here designates a cutting plane perpendicular to the direction of extension A of the conduits 31, 33 and the channels 51, 71, the direction of extension A defining the direction of flow of the fluids through the channels and conduits. It is also the direction in which the channels and conduits are parallel to each other.
[0071] In a plane perpendicular to direction A, the exchanger comprises four circular walls 41, 43, 45 and 47. These walls are centered in the same way, so that they are concentric.
[0072] The first wall 41 of smaller diameter defines the conduit 31 on the inside. In other words, the flow of fuel which flows through the conduit 31 flows inside the first circular wall 41.
[0073] The second wall 43 directly surrounds the first wall 41, that is to say that the second wall 43 has a diameter greater than the diameter of the first wall 41 and it is opposite the first wall 41. The annular cavity located between the walls 41 and 43 defines the channel 51. In other words, the flow of lubricant which flows through the channel 51 flows inside the second circular wall 43 and outside the first wall 41.
[0074] The third wall 45 directly surrounds the second wall 43, that is to say that the third wall 45 has a diameter greater than the diameter of the second wall 43 and it faces the second wall 43. The annular cavity located between the walls 43 and 45 defines the channel 71. In other words, the flow of lubricant which flows through the channel 71 flows inside the third circular wall 45 and outside the second wall 43. The fourth wall 47 directly surrounds the third wall 45, that is to say that the fourth wall 47 has a diameter greater than the diameter of the third wall 45 and it faces the third wall 45. The annular cavity located between the walls 45 and 47 defines the conduit 33. In other words, the flow of lubricant which flows through the conduit 33 flows inside the fourth circular wall 47 and outside the third wall 45. the outside of the third wall 45.
[0075] In a second embodiment, the conduits and channels each have a polygonal profile in section, the profiles of the channels and conduits having the same number of sides.
[0076] In a plane perpendicular to direction A, the exchanger comprises different rectilinear walls which define polygonal profiles of the conduits and channels.
[0077] For example, the profile of each channel or conduit is a triangle. Some straight walls, that is, some sides of a triangle, can separate one channel from another channel or one channel from a conduit. Such a side can put the two channels or the channel and the conduit into thermal contact.
[0078] For example, the profile of each channel or duct is a rectangle. Some straight walls, that is, some sides of a rectangle, can separate one channel from another channel or one channel from a duct. Such a side can put the two channels or the channel and the duct in thermal contact.
[0079] In a third example related to Figure 4, the profile of each channel or conduit is a hexagon, and the different hexagons defined are all the same size.
[0080] In this third example, the fuel circuit comprises a plurality of conduits 35 in the heat exchanger. They are colored by the same gray level in Figure 4.
[0081] Each lubricant circuit comprises a plurality of channels in the heat exchanger, respectively channels 53 for a first lubricant circuit and channels 73 for a second lubricant circuit. Channels 53 are colored by the same level of gray, darker than for conduits 35. Channels 73 are colored by the same level of gray, darker than for channels 53 in Figure 4.
[0082] The conduits 35 and the channels 53, 73 form a honeycomb structure.
[0083] The exchanger can be configured so that two channels of the same lubricant circuit are not contiguous and that two conduits are not contiguous. This situation is shown in Figure 4 and according to it: - each conduit 35 is contiguous to one, two or three channels 53, and contiguous to one, two or three channels 73,
[0084] - each channel 53 is contiguous to one, two or three conduits 35, and contiguous to one, two or three channels 73, and
[0085] - each channel 73 is contiguous to one, two or three conduits 35, and contiguous to one, two or three channels 53.
[0086] In this case, the heat exchange surfaces within the heat exchanger are distributed equally between the different fuel / first lubricant, fuel / second lubricant and first lubricant / second lubricant pairs.
[0087] In another configuration of the exchanger with the honeycomb structure, the heat exchange surface can also be increased for one of these pairs compared to two others. To do this, one conduit can be replaced by a channel, a channel of the first lubricant by a channel of the second lubricant.
[0088] The various forms of exchanger mentioned here can be produced using additive manufacturing. They can also be produced using more traditional manufacturing processes.
[0089] Heat exchange process
[0090] A turbomachine comprising a heat exchanger as just presented makes it possible to implement a method according to the invention for carrying out heat exchanges between two lubricant circuits and a fuel circuit.
[0091] We will present a method of implementing this process.
[0092] During a first step E1 of the method, two first flows of a first fluid are produced. More precisely, the circuit of this first fluid is configured to circulate the first fluid according to two separate and locally parallel flows. These two flows flow for example through the two conduits 31, 35 of the first fuel circuit inside the heat exchanger 11.
[0093] During a second step E2 of the process, a second flow of a second fluid and a third flow of a third fluid are produced.
[0094] More specifically, each second fluid and third fluid circuit is configured to circulate a second fluid or a third fluid in two separate and locally parallel flows.
[0095] These two flows flow for example through two channels 51, 71, each channel being included in one of the second or third circuits inside the heat exchanger 11. The second flow and the third flow are in thermal contact. This is obtained in particular by imposing the channels 51, 71 contiguous. The thickness and the nature of material in the heat exchanger which separates the channels 51, 71 are adapted to allow heat exchanges between the second flow and the third flow.
[0096] The first two streams, the second stream and the third stream flow in flow directions that are locally parallel to each other.
[0097] In addition, each of the second flow and the third flow is in thermal contact with one of the first two flows. This is obtained in particular by requiring that each channel 51, 71 is contiguous to one of the conduits 31, 33. The thickness and the nature of the material in the heat exchanger which separates the channel and the conduit are adapted to allow heat exchanges.
[0098] A preferred mode corresponds to the case where the first fluid is a fuel, and the second fluid and the third fluid are lubricants.
[0099] In this preferred mode, regardless of the flight point, the fuel flow always acts as a cold source within the exchanger.
[0100] On the other hand, the lubricant flows can change role depending on the point of flight.
[0101] We consider the case of a turbomachine comprising a high-pressure body, a low-pressure body, a high-pressure electric generator driven by the shaft of the high-pressure body and a low-pressure electric generator driven by the shaft of the low-pressure body. We choose the lubricant circuits passing through the heat exchanger as the oil circuit of the high-pressure electric generator and the oil circuit of the low-pressure electric generator.
[0102] It turns out that these lubrication circuits have different cooling requirements depending on the operating point of the turbomachine or aircraft.
[0103] To illustrate the above point, let us consider as an example a first operating point for which the aircraft is on the ground on a hot day. In this case, the lubrication circuit of the low-pressure electric generator requires cooling while the lubrication circuit of the high-pressure electric generator does not have this need. For this situation, the lubrication circuit of the low-pressure electric generator acts as a heat source while the lubrication circuit of the high-pressure electric generator acts as a cold source within the heat exchanger.
[0104] Still as an example, let us consider a second operating point corresponding to the case where the aircraft is in maximum climb, typically after takeoff to reach a safety altitude. In this case, it is the lubrication circuit of the high-pressure electric generator that needs to be cooled while the lubrication circuit of the low-pressure electric generator does not have this need. For this situation, the lubrication circuit of the high-pressure electric generator acts as a heat source while the lubrication circuit of the low-pressure electric generator acts as a cold source within the heat exchanger.
[0105] It thus becomes possible to exploit all available cold sources in order to cool the lubricant flows thanks to the heat exchanger allowing heat exchanges between 3 fluids.
Claims
DEMANDS 1. Turbomachine comprising: - a heat exchanger (11), - a first circuit (13) of a first fluid, the first circuit (13) comprising two conduits (31, 33) in the heat exchanger (11), - a second circuit (15) of a second fluid and - a third circuit (17) of a third fluid, each of the second circuit and the third circuit comprising a channel (51, 71) in the heat exchanger (11), each channel (51, 71) being contiguous to one of the conduits (31, 33) so as to be in thermal contact with one of the conduits (31, 33), the channels (51, 71) being contiguous to each other so as to be in thermal contact with each other, the heat exchanger (11) comprising a section in which the conduits (31, 33) and the channels (51, 71) are locally parallel to each other.
2. Turbomachine according to claim 1 in which the first fluid is a fuel, the second fluid and the third fluid are lubricants.
3. Turbomachine according to claim 2 comprising a high-pressure body, a high-pressure electric generator driven by a shaft of the high-pressure body, a low-pressure body and a low-pressure electric generator driven by a shaft of the low-pressure body, the lubrication circuits being an oil circuit of the high-pressure electric generator and an oil circuit of the low-pressure electric generator.
4. Turbomachine according to any one of claims 2 or 3 wherein each conduit (31, 33) is contiguous to one of the channels (51, 71) so as to be in thermal contact with one of the channels (51, 71).
5. Turbomachine according to any one of claims 2 to 4 in which the heat exchanger (11) is configured so that fuel flows into the conduits (31, 33) in a direction opposite to a direction of flow of lubricants in the channels (51, 71).
6. Turbomachine according to any one of claims 2 to 4 in which the heat exchanger (11) is configured so that fuel flows into one of the conduits in a direction opposite to a direction of fuel flow into the other of the conduits.
7. Turbomachine according to any one of claims 2 to 6 in which the conduits (31, 33) and the channels (51, 71) have circular walls in section with the same center.
8. Turbomachine according to any one of claims 2 to 6 in which the ducts and channels each have a polygonal profile in section, the profiles of the channels and ducts having the same number of sides.
9. Turbomachine according to claim 8 wherein the fuel circuit comprises a plurality of conduits in the heat exchanger and each lubricant circuit comprises a plurality of channels in the heat exchanger, the conduits and channels forming a honeycomb structure, the exchanger being configured such that two channels of the same lubricant circuit are not contiguous and no two conduits are contiguous.
10. Aircraft comprising a turbomachine according to one of the preceding claims.
11. Heat exchange process in a turbomachine comprising a stage of generating first two streams of a first fluid, a stage of generating a second stream of a second fluid and a third stream of a third fluid, the second and third streams being in thermal contact with each other, the first two streams, the second stream and the third stream flowing in locally parallel flow directions, each of the second and third streams being in thermal contact with one of the first two streams.
12. Heat exchange process according to claim 11 wherein the first fluid is a fuel, the second fluid and the third fluid are lubricants.