HEAT EXCHANGER MOUNTED IN A TURBINE ENGINE CAVITY

A heat exchange system for a turbine engine is provided. The heat exchange system includes a cavity having an air intake, a heat exchanger arranged in the cavity and having a first circuit in which a first fluid can circulate, a movable flap mounted at the air intake and moving between two positions permitting or preventing, respectively, the circulation of air flow in the cavity, and a control device having a movable member configured to drive the movement of the movable flap. The control device can be arranged in the heat exchanger supply circuit and configured so as to permit or prevent the circulation of the first fluid to the heat exchanger and simultaneously move the movable flap between at least one of the two positions.

FIELD OF THE INVENTION

The present invention relates to the general field of the aeronautic. In particular, it refers to a heat exchange system comprising a heat exchanger which is buried in a cavity of a turbine engine. The invention also relates to the turbine engine and the method for implementing the heat exchange system.

TECHNICAL BACKGROUND

A turbine engine, in particular for an aircraft, comprises various members and/or items of equipment that need to be lubricated and/or cooled, such as rolling bearings and gears. The heat released by these components, which can be very high depending on the power of the member and/or the item of equipment, is transported by a fluid and evacuated towards cold sources available in the aircraft.

It is known to equip the turbine engine with one or more heat exchangers to carry out the heat exchange between the fluid (typically oil) and the cold source (air, fuel, etc.). There are different types of heat exchangers, for example the fuel/oil heat exchangers, generally referred to as Fuel Cooled Oil Cooler for FCOC, and the air/oil heat exchangers, referred to as Air-Cooled Oil Cooler for ACOC. These are usually installed in addition to the FCOC exchangers, which are insufficient to meet the growing need for fluid cooling in the turbine engine. Examples of heat exchangers are described in the patent documents EP-A2-2492199, US-A1-2019/390602, and EP-A1-3453845.

The family of the ACOC exchangers also comprises the surface-type exchangers, known by the acronym SACOC for “Surface Air-Cooled Oil Cooler”, which are generally arranged in the secondary duct of the turbine engine and use the secondary airflow to cool the oil circulating in the turbine engine. However, the SACOC heat exchangers usually comprise fins that continuously disturb the airflow and create additional pressure losses in the secondary duct. This affects the performance of the turbine engine as well as the specific fuel consumption.

To overcome these disadvantages, some heat exchangers are buried in a compartment of the turbine engine. As illustrated inFIG.1of the prior art, a heat exchanger A is integrated in a cavity B opening into a radially internal wall C of the secondary duct. A portion of the secondary airflow, collected from the secondary duct, passes through the buried heat exchanger A where it is reheated and reinjected into the secondary duct. The heat exchanger A is in the form of a metallic surface part allowing the passage of oil in machined channels D and carrying fins E which are intended to be passed through by the secondary airflow. A driven scoop F, formed for example by a movable flap pivoting and/or displaceable in translation, is arranged at the level of the entrance of the cavity B so as to extend into the secondary duct and to provide an adjustable air flow rate towards the buried heat exchanger A. An example of this heat exchanger is described in the patent application EP-A1-2472067.

The movable flap of the scoop F can generate pressure losses in the secondary duct when it is open. The movable flap is driven so that it closes when there is no need for heat exchange in the buried heat exchanger. In the closing position of the movable flap, the hot oil continues to circulate inside the heat exchanger, heating all the air trapped in it (the airflow is almost trapped if the movable flap is in the closing position) and in the cavity. The heated airflow is discharged into the secondary duct. The continuously circulating hot oil can shorten the service life of the heat exchanger and the performance of the turbine engine is degraded. A thermal cycling is operated on every flight even if the heat exchanger is not used to cool the oil.

There is therefore a need to overcome the above-mentioned disadvantages.

SUMMARY OF THE INVENTION

The objective of the present invention is to provide a heat exchange system that allows to optimise the integration of a heat exchanger in a cavity and reduces the pressure losses while maintaining the performance of the turbine engine throughout its operation.

This is achieved in accordance with the invention by a heat exchange system for an aircraft turbine engine comprising:a cavity comprising an air intake,a heat exchanger arranged in the cavity, the heat exchanger comprising a first circuit in which a first fluid provided by a fluid supply circuit is able to circulate,a movable flap mounted at the level of the air intake and displacing between an opening position allowing the circulation of the airflow into the cavity and a closing position preventing the circulation of the airflow into the cavity,a control device comprising at least one movable member intended to cause the displacement of the movable flap,the control device being arranged in the fluid supply circuit for supplying the fluid to the heat exchanger, and being configured so as to allows or prevent the circulation of the first fluid towards the heat exchanger and to act simultaneously on the opening or closing position of the movable flap.

Thus, this solution allows to achieve the above-mentioned objective. In particular, the coupling of the position of the movable flap and of the position of the movable member allows an adaptation to the different phases of flight of the turbine engine and of the aircraft. The use of the heat exchanger in certain flight conditions of the turbine engine allows for an increase in its service life and possibly a gain in weight. In particular, this configuration allows to avoid the overheating of the cavity in which the heat exchanger is installed, reduces the thermal cyclane of the heat exchanger and the pressure losses.

The heat exchange system also comprises one or more of the following characteristics, taken alone or in combination:the control device is intended to be connected, on the one hand, to a supply conduit connected to the first circuit of the heat exchanger and, on the other hand, to a bypass conduit which bypasses the heat exchanger, said supply conduit being intended to be supplied by the supply circuit when the movable flap occupies the opening position and said bypass conduit being intended to be supplied by the supply circuit when the movable flap occupies the closing position.the movable member displaces between:a first position allowing the circulation of the first fluid towards the heat exchanger and in which the movable flap is in the opening position, anda second position allowing the circulation of the first fluid towards the bypass conduit and in which the movable flap is in the closing position.the heat exchange system comprises means for measuring at least one determined parameter of the first fluid at the outlet of the heat exchanger, depending on the orientation of circulation of the first fluid in the heat exchanger, and which are capable of being connected to an electronic control unit, the electronic control unit being configured so as to drive the passage from one position to another of the movable member according to the determined parameter.the control device comprises a body provided with a housing into which a first inlet orifice, a second inlet orifice, a first outlet orifice and a second outlet orifice open, the first and second inlet orifices being intended to be connected to the supply circuit, the first outlet orifice being intended to be connected to the first circuit and the second outlet orifice being intended to be connected to the bypass conduit, the movable member sealing the second outlet orifice in the first position and sealing the first outlet orifice in the second position.the movable member is able to occupy at least one intermediate position in which the first fluid is able to circulate towards the heat exchanger and towards the bypass conduit.the first fluid comprises oil.the determined parameter of the first fluid is the temperature of the first fluid at the outlet of the heat exchanger.the movable member comprises an actuating rod hinged to the movable flap.

The invention also relates to a turbine engine module comprising an annular compartment about the longitudinal axis X, a fluid supply circuit and a heat exchange system having any of the above characteristics, the compartment comprising an annular wall which guides at least partly an airflow, and the heat exchange system being arranged in the annular compartment and on the supply circuit, the air intake of the cavity being arranged in the annular wall so as to be in fluidic communication with the annular compartment.

The invention also relates to an aircraft turbine engine comprising a turbine engine module as described above or a heat exchange system as described above.

The invention also relates to a method for regulating the circulation of a first fluid through a heat exchanger of a heat exchange system for a turbine engine, the heat exchanger being arranged in a cavity of a compartment of the turbine engine and the cavity being capable of being swept by an airflow, the method being characterised in that it comprises:a step of providing a first fluid into a fluid supply circuit of the turbine engine,a step of arranging the heat exchanger and a control device on the supply circuit,a step of regulating so as to simultaneously allow or prevent the circulation of the airflow in the cavity and the circulation of the first fluid towards the heat exchanger.

The method also comprises one or more of the following characteristics or steps, taken alone or in combination:the regulation step comprises:a sub-step of displacing the movable member to the first position to allow the oil to circulate towards the first circuit of the heat exchanger or to the second position to allow the oil to circulate towards the bypass conduit,a sub-step of actuating the movable flap into an opening position allowing the airflow to circulate in the cavity and a closing position preventing the airflow to circulate in the cavity, the position of the movable flap being a function of the position of the movable member.a step of measuring a determined parameter of the first fluid and in that the displacement step is carried out as a function of at least reaching a threshold of said predetermined parameter.the determined parameter measured is a temperature representative of the temperature of the first fluid in the heat exchanger, measured continuously or discretely at regular intervals, and in that at each measurement the regulation step performs at least one of the following steps before a subsequent measurement of the temperature:when the measured temperature is below at least one setpoint temperature threshold, the movable member is driven to displace to the second position so as to supply the bypass conduit with the first fluid,when the measured temperature is equal to said setpoint temperature threshold, the movable member is driven to displace to its previous position, and/orwhen the measured temperature is above said setpoint temperature threshold, the movable member is driven to displace to the first position so as to supply the supply conduit with the first fluid towards the heat exchanger.

The invention also relates to an aircraft comprising a heat exchange system or a turbine engine as described.

DETAILED DESCRIPTION OF THE INVENTION

FIG.1has been described in the above.

FIG.2shows an axial cross-sectional view of a turbine engine1of longitudinal axis X to which the invention applies. The turbine engine1shown is a turbofan engine for mounting on an aircraft. Of course, the invention is not limited to this type of turbine engine.

In the present invention, the terms “upstream” and “downstream” are defined in relation to the circulation of the gases in the turbine engine1and here along the longitudinal axis X and with reference toFIG.1from left to right. The terms “radial”, “internal” and “external” are defined with respect to a radial axis Z perpendicular to the longitudinal axis X and with respect to the distance from the longitudinal axis X. Similarly, a turbine engine usually consists of several modules that are manufactured independently of each other and then assembled together in a way that facilitates its assembly, its disassembly and its maintenance.

This double-flow turbine engine1generally comprises a gas generator or gas turbine engine2with a fan3mounted upstream. The gas generator2comprises a gas compressor assembly (here comprising a low pressure compressor4aand a high pressure compressor4b), a combustion chamber5and a turbine assembly (here comprising a high pressure turbine6aand a low pressure turbine6b). Typically, the turbine engine comprises a low pressure shaft7that connects the low pressure compressor4aand the low pressure turbine6bto form a low pressure body and a high pressure shaft8that connects the high pressure compressor4band the high pressure turbine6ato form a high pressure body. The low pressure shaft7, centred on the longitudinal axis, causes a fan shaft9in this example. A speed reducer10may be interposed, as here, between the fan shaft9and the low pressure shaft7. Upstream and downstream rotation guide bearings11allow to guide the low-pressure shaft7in rotation relative to a stationary structure of the turbine engine.

The fan3is faired in a fan casing12carried by a nacelle13and generates a primary airflow F1which circulates through the gas generator2in a primary duct14and a secondary airflow F2which circulates in a secondary duct15around the gas generator2. The secondary airflow F2is ejected through a secondary nozzle16terminating the nacelle13while the primary airflow F1is ejected outside the turbine engine via an ejection nozzle17located downstream of the gas generator2.

The guide bearings11and the speed reducer10in this example turbine engine configuration need to be lubricated and/or cooled to ensure good performance of the turbine engine. The power generated by these is dissipated in a fluid coming from a fluid supply source installed in the turbine engine, which allows to lubricate and/or cool various members and/or equipment of the turbine engine. Of course, other items of equipment of the turbine engine generates a lot of heat that must be extracted from its environment.

With reference toFIGS.2and3, the turbine engine1comprises a heat exchange system20which allows the cooling of the fluid intended to lubricate and/or cool these members and/or items of equipment. The heat exchange system20comprises a heat exchanger21shown very schematically. The heat exchanger21is mounted in a compartment in which an airflow circulates. The compartment may be an inter-duct casing18, the fan casing12or the nacelle13. The inter-duct casing18separates the primary duct14and the secondary duct15. This inter-duct casing18carries a splitter nose19upstream and the ejection nozzle17of the gases downstream.

InFIG.3, the heat exchanger21is arranged in a cavity22, around the longitudinal axis, which is intended to be passed through by an airflow, in particular the secondary airflow F2. In the present example, the cavity22is arranged in the inter-duct casing18. The cavity22comprises an air intake23which is in fluidic communication with the secondary duct15. The cavity22also comprises an air exhaust24which is in fluidic communication with the secondary duct15. In the example shown, the air intake23, as well as the air exhaust24are formed in a radially internal wall25of the inter-duct casing18. The radially internal wall25is intended to guide at least partly the secondary airflow F2into the secondary duct15. The cavity22also extends over an angular sector, in a circumferential direction about the longitudinal axis X, of the order of 30°.

The heat exchanger21comprises a first circuit26in which a first fluid is able to circulate and a second circuit27in which a second fluid is able to circulate. The first fluid is an oil and the second fluid is the airflow circulating in the turbine engine and in this case a portion of the secondary airflow collected from the secondary duct15. The airflow is the cold source intended to cool the hot oil heated by the members/equipment of the turbine engine. The heat exchanger21is of the air/oil surface type.

Several oil channels26aare arranged in the thickness of an internal wall and an external wall along the radial axis in the heat exchanger21. These oil channels26acommunicate with each other and form the first circuit26. The latter comprises an inlet26band an outlet26c.The second circuit27extends between the internal and external walls of the heat exchanger21. These walls are radially spaced from each other forming a channel. The air flow circulates through the channel. Each of the walls comprising the channels26ais swept by the airflow so as to carry out an exchange with them. The heat exchanger21may comprise a plurality of fins27aeach extending radially from at least one of the internal and external walls. The fins allow to increase the contact area with the secondary airflow to extract calories.

The heat exchanger21is mounted on a fluid (oil) supply circuit28of the turbine engine1. The oil supply circuit28comprises, generally and in the orientation of flow of the oil, an oil source29, at least one supply pump30intended to allow the circulation of oil in the supply circuit28from the oil source29, at least one filter31, and at least one recirculation pump32. The oil source29here comprises a tank29a.The heat exchanger21is typically arranged downstream of the supply pump30and also upstream of the members and/or equipment to be lubricated and/or cooled. These are typically located in lubrication chambers33. The recirculation pump32allows oil to be recirculated from the members and/or equipment towards the tank29a.The first circuit26of the heat exchanger is a segment of the supply circuit28.

The heat exchange system20further comprises a driven scoop34, formed by a movable flap, to allow or prevent the circulation of a portion of the secondary airflow into the cavity22and in particular through the heat exchanger21. The movable flap34is arranged at the level of the air intake23of the cavity22. Specifically, the movable flap34is displaceable between an opening position in which the airflow is allowed to circulate into the cavity (and also into the compartment or around the inter-duct casing18) and a closing position in which the airflow is not allowed to circulate into the cavity22(the airflow only circulates into the compartment or around the inter-duct casing (i.e. into the secondary duct15).

Advantageously, the movable flap34is mounted so as to pivot about an axis35transverse to the longitudinal axis X. A pivot connection is provided between the movable flap34and a segment of the radially internal wall25of the inter-duct casing18. The movable flap34also has dimensions substantially corresponding to those of the air intake23. In particular, the movable flap34extends over an angular sector of the order of 30° in the circumferential direction.

As can be seen inFIG.3, the heat exchange system20comprises a control device36which is configured to act (prevent or allow) on the circulation of the first fluid (oil), towards the heat exchanger2(i.e. in the first oil circuit) and simultaneously on the position of the movable flap34. More specifically, the control device36is configured to associate the closing position of the movable flap34with a bypass conduit37bypassing the heat exchanger21to avoid a temperature rise in it and in the cavity22. The control device36is arranged in the supply circuit28.

With reference toFIG.4, the control device36is in the form of a distribution valve which comprises a body38provided with a housing39or bore and a movable member40displacing in the housing39between a first position allowing oil to circulate towards the heat exchanger21and a second position allowing oil to circulate into the bypass conduit37. In particular, in the second position, the oil is not allowed to circulate towards the heat exchanger21. The movable member40is intended to cause or actuate the displacement of the movable flap34. For this purpose, the movable member40comprises an actuating rod41, the free end42of which is hingedly attached to the movable flap. The actuating rod41extends at least partly outside the body38. In this way, when the movable member40is displaced from its first position to its second position, the latter causes the movable flap34to displace into the opening or closing position. According to an example of embodiment not shown, the free end42of the actuating rod41is directly hinged to the movable flap. Alternatively, and as illustrated inFIG.3, a connecting rod43comprises a first end43awhich is hingedly attached to the movable flap34and a second end43bwhich is attached to the free end42of the actuating rod41of the movable member40. In yet another alternative (not shown), a connecting rod and a movable part are arranged between the movable flap34and the movable member40for changing the position of the movable flap. In particular, the first end of the connecting rod is hinged to the movable flap34and the second end of the connecting rod is hinged to the movable part. The latter, for example in the form of an angle, pivots around an axis transverse to the longitudinal axis of the turbine engine. The movable part is also hinged to the free end of the actuating rod41.

With reference toFIGS.4to5, the control device36is intended to be connected, on the one hand, to a first supply conduit49connected to the first circuit26of the heat exchanger21and, on the other hand, to the bypass conduit37which bypasses the heat exchanger21. In particular, the body38comprises a first inlet orifice44, a second inlet orifice45, a first outlet orifice46and a second outlet orifice47opening into the housing39. The first and second inlet orifices44,45are intended to be connected to the supply circuit28. The first outlet orifice41is intended to be connected to the first circuit26of the heat exchanger21. The movable member40defines a first chamber48aand a second chamber48bin the body38which are hermetically separated. The volume of the chambers48a,48bvaries as the movable member40displaces within the body38. In the present example, the movable member40displaces in a translational manner. As illustrated, the first inlet orifice44is in fluidic communication with the first chamber48a.The first outlet orifice46is also in fluidic communication with the first chamber48a.The first supply conduit49is arranged on the supply circuit28so as to connect the first circuit26of the exchanger21to the control device36. The conduit49comprises an inlet49aconnected to the first outlet orifice46of the device36and an outlet49bconnected to the inlet26bof the first circuit26of the heat exchanger21.

The second inlet orifice45is in fluidic communication with the second chamber48b.The second outlet orifice47is also in fluidic communication with the second chamber48b.The bypass conduit37comprises an inlet37awhich is connected to the second outlet orifice47of the control device36. This bypass conduit37also comprises an outlet37bwhich is arranged downstream of the heat exchanger (downstream of the outlet26cof the first circuit26). More specifically, the outlet37bis arranged between the tank29aand the heat exchanger21. The output26cof the first circuit26is coupled to a second conduit50of the supply circuit28.

The displacement of the movable flap34is coupled to the fluid circulation in the bypass conduit so as to avoid the overheating of the cavity22in which the heat exchanger21is arranged and also to the fluid circulation in the heat exchanger21itself (in the first circuit). For this purpose, when the movable member40is in the first position (oil circulation in the first circuit26), the movable flap34is in the opening position. In this case, the oil circulating through the heat exchanger21is cooled by a portion of the secondary airflow passing through the heat exchanger21. In this position, as shown inFIG.4, the movable member40seals the second inlet orifice45and also the second outlet orifice47.

Conversely, when the movable member40of the control device36is in the second position (oil circulation in the bypass conduit37then the movable flap34is in the closing position. No portion of the secondary airflow is collected from the secondary duct15, which optimises the performance of the turbine engine, and the hot oil coming from the members and/or equipment to be lubricated and/or cooled is redirected towards the tank29aso as to avoid a rise in temperature in the heat exchanger21and in the cavity22. In this position, as shown inFIG.5, the movable member40seals the first inlet orifice44and also the first outlet orifice46.

Advantageously, the heat exchange system20comprises means for measuring51at least one determined parameter of the first fluid (oil) in the turbine engine1. The measuring means51are connected to an electronic control unit60of the turbine engine. This electronic control unit60is configured to drive the passage from one position to another of the movable member40of the control device36according to the determined parameter. The means51for measuring the determined parameter may be a sensor, a probe, a thermocouple or any element capable of measuring a determined parameter in the turbine engine. The temperature of the oil leaving the heat exchanger21is an example of a determined parameter. The viscosity of the oil can also be measured. As shown inFIG.3, the measuring means51are installed in the conduit50of the oil supply circuit28and downstream of the heat exchanger21. The electronic control unit60delivers a control command to the control device36when the measured temperature is higher, lower or reaches at least one temperature threshold to change from one position to another. Advantageously, but not restrictively, the temperature threshold is between 20° C. and 100° C. The temperature threshold is stored in a memory (not shown) in the electronic control unit60. The first position of the movable member (opening position of the movable flap) is considered to be a default position. That is, when the turbine engine is started, the movable flap34is opened or opens and oil circulates towards the heat exchanger21. When the measured temperature reaches or falls below the temperature threshold, the movable member40moves to the second position to close the movable flap34and allow the oil to circulate towards the bypass conduit37.

Alternatively, several temperature thresholds are stored in the memory of the electronic control unit60. A first temperature threshold is associated with the first position of the movable member40or of the opening position of the movable flap34. A second threshold is associated with the second position of the movable member34or of the closing position of the movable flap34. The first temperature threshold may be 20° C. and the second temperature threshold may be 100° C.

In an embodiment illustrated inFIG.6, the movable member40of the control device36may occupy an intermediate position. In this case the movable flap34has an intermediate opening angle in an intermediate position as well. In this example, the intermediate position is located between the first position and the second position. The control device36is configured to have an oil flow rate at its output that is specific to each position of the movable flap. In particular, when the movable flap34is in the opening position, the entire oil flow rate circulates towards the heat exchanger21. When the movable flap34is in the closing position, all the oil flow rate circulates towards the bypass conduit37. In the intermediate position, the control device36simultaneously allows the oil to circulate towards the heat exchanger21and towards the bypass conduit37. The oil flow rate towards the heat exchanger21is identical to the oil flow rate towards the bypass conduit37. The movable flap34also occupies its intermediate position between the opening position and the closing position. The first and second inlet orifices44,45and the first and second outlet orifices46,47are not sealed. Similarly, the intermediate position of the control device36is associated here with a third temperature threshold. The latter is between the first threshold and the second threshold of temperature. Advantageously, the values of the different thresholds are spaced apart or respect a certain hysteresis to avoid flapping (oscillations) of the movable flap34. For example, the third temperature threshold is 80° C.

Alternatively, as shown inFIG.7, when the control device36switches to the intermediate position, the oil flow rate circulating towards the heat exchanger21is less than the oil flow rate towards the bypass conduit37. The oil flow rate towards the heat exchanger21may be 25% of the total oil flow rate entering into the control device36while the oil flow rate towards the bypass conduit37may be 75% of the total flow rate. For this purpose, the first inlet orifice44and the first outlet orifice46are partially sealed. Of course, the percentage of the flow rate distributed can be different.

Advantageously, but not restrictively, the control device36is a hydraulic distributor which is mounted on the supply circuit28of the turbine engine. The distributor comprises a drawer as a movable member.

An example of a method100for regulating the circulation of the oil in the heat exchanger21of the heat exchange system20as described above will be presented. The steps of the method are shown inFIG.8. The method comprises a first step of providing110a first fluid (in this case oil) to a supply circuit28. The method also comprises, before or after step110, a step of arranging120the heat exchanger21and a control device36on the supply circuit28. As we have seen and in particular inFIG.3, the control device36is arranged, following the circulation of the first fluid in the supply circuit28, between the heat exchanger21and the tank29a(or fluid source). The method100comprises a step of regulating or managing130differentially (allowing or preventing) and simultaneously the circulation of the airflow in the cavity22and the circulation of the first fluid towards the heat exchanger21. The regulation step130comprises a sub-step131of displacing the movable member40into the first position to allow the oil to circulate towards the first circuit26of the heat exchanger21(via the supply conduit49) or into the second position to prevent the oil circulation towards the heat exchanger21. In the second position, the oil is returned towards the tank without passing through the heat exchanger21. This step130also comprises a sub-step of actuating132the movable flap34which is dependent on the position of the movable member40. In the first position of the movable member40, the movable flap34occupies the opening position to allow the circulation of the airflow into the cavity22. And in the second position of the movable member40, the movable flap34occupies the closing position to prevent the circulation of the airflow into the cavity. In particular, when the movable flap34occupies the opening position, the supply conduit49is supplied by the supply circuit28and when the movable flap34occupies the closing position the bypass conduit37is supplied by the supply circuit28.

The change in position of the movable member40depends on a predetermined parameter of the first fluid. To this end, the method100also comprises a step of measuring140a determined parameter (the temperature in or at the outlet of the heat exchanger) of the first fluid to carry out the displacement sub-step. For this purpose, the measuring means51send information about the temperature of the oil leaving the heat exchanger21. Each measured temperature is compared with the temperature threshold or thresholds stored in the memory of the electronic control unit60. When the measured temperature reaches, falls below or exceeds one of the temperature thresholds, the electronic control unit60sends a control command to the control device36. In particular, the control command drives the displacement of the movable member40into the first position, into the second position, into its holding position or possibly into the intermediate position. For example, the temperature of the first fluid in the heat exchanger, or at the outlet of the heat exchanger, is measured continuously or discretely at regular intervals. The regulation step performs, at least before a subsequent measurement of the temperature, a step consisting of the fact that when the measured temperature is lower than at least one setpoint temperature threshold, the movable member40is driven to displace into the second position so as to supply the bypass conduit37with the first fluid. The regulation step may perform, at least prior to a subsequent measurement of the temperature, a step consisting of the fact that when the measured temperature is equal to said setpoint temperature threshold, the movable member40is driven to displace to its previous position. The regulation step may perform, at least prior to a subsequent measurement of the temperature, a step consisting of the fact that when the measured temperature is above said setpoint temperature threshold, the movable member40is driven to displace to the first position so as to supply the supply conduit49with the first fluid towards the heat exchanger.

Thus, the closing of the movable flap34and the circulation of the oil through the bypass conduit37(bypassing the heat exchanger21) allows to reduce the thermal cycling in the heat exchanger and to reduce the pressure losses in the first oil circuit. Such reductions allow to a gain in the service life of the heat exchanger, and also in the performance and the efficiency of it and other members of the supply circuit28. Similarly, the temperature to be borne by the cavity22can be weighted so as to obtain mass gains in the materials used (e.g. composites), particularly for the walls of the cavity22and those of the exchanger21.