Improved heat exchanger arrangement for aircraft turbomachine

Abstract

A heat exchanger arrangement (1) for an aircraft turbomachine, comprising: a heat exchanger body (30); an upstream hot fluid header (12) attached to the heat exchanger body (30) and configured to collect a first fluid at a first temperature and to supply the first fluid to the heat exchanger body (30); an upstream cold fluid header (22) attached to the heat exchanger body (30) and configured to collect and supply a second fluid at a second temperature lower than the first temperature to the heat exchanger body (30), at least the upstream hot fluid header (12) comprising a double wall (120) forming a peripheral cavity (16) surrounding the main cavity (125), the main chamber is configured to receive a primary flow of a first fluid and the peripheral chamber (16) is configured to receive a secondary flow of the first fluid or a second fluid.

Description

Technical Field

[0001] The present disclosure relates to a heat exchanger arrangement for an aircraft turbomachine, such as in particular a turboprop or turbojet. The present disclosure also relates to a turbomachine comprising such a heat exchanger arrangement. Background Art

[0002] To meet various needs, heat exchangers or heat exchangers are used in aircraft turbomachines, for example, hot air / gas exchangers, which recover hot gases from the nozzle outlet to heat the air entering the combustion chamber; so-called "intercooler" air / air exchangers, which are used to cool the hot compressor inter-air with ambient air; nozzle heat exchangers, which are used to reheat low-temperature fuel; or heat exchangers for ambient air cooling of the air collected from the compressor inter-air and intended to be delivered to the cabin air conditioning system.

[0003] Figure 1 A cross-sectional elevational view of a heat exchanger device 1' of the cross-flow type according to the prior art is schematically illustrated, the heat exchanger device comprising: a first flow 10, which is called "hot flow"; and a second flow 20, which is called "cold flow". In fact, as is well known, the heat exchangers used for the above applications involve: a hot fluid at high temperature (which is usually a compressible fluid in a gaseous state with a temperature variation between 400°C and 1000°C) and a cold fluid at low temperature (which is usually between -150°C and 400°C).

[0004] Typically, the heat exchanger includes a header located at the inlet and / or outlet of the heat exchanger body 30, thereby ensuring the distribution of the hot fluid and the cold fluid located at the inlet and / or outlet of the heat exchanger body. In this way, from upstream to downstream (according to the flow direction of the hot fluid), the hot flow 10 includes an upstream hot fluid header 12, channels of the heat exchanger body 30, and a downstream hot fluid header 14. The upstream hot fluid header 12 is configured to collect a first fluid referred to as "hot fluid" in a separate section (not illustrated) of the turbine. For example, the upstream hot fluid header 12 can collect the hot gas when it is discharged from the low-pressure turbine, and convey the hot gas to the heat exchanger body 30 in which the cold fluid also circulates.

[0005] Therefore, it should be understood that the upstream hot fluid header 12 extends between a first upstream end 12a for collecting high-temperature hot fluid and a second downstream end 12b attached to the heat exchanger body 30, through which the hot fluid is injected into one or more channels of the heat exchanger body 30. The downstream hot fluid header 14 also extends between a first upstream end 14a attached to the heat exchanger body 30 and a downstream end 14b communicating with a separate part of the turbine (not shown), through which the hot fluid that has circulated in the heat exchanger body 30 is recovered.

[0006] Similarly, from upstream to downstream (according to the flow direction of the cold fluid), the cold flow 20 includes an upstream cold fluid header 22, channels of the heat exchanger body 30, and a downstream cold fluid header 24. The upstream cold fluid header 22 is configured to collect a second fluid, referred to as “cold fluid”, in a separate section (not shown) of the turbine, such as in a secondary air flow path.

[0007] It should be understood that the upstream cold fluid header 22 extends between a first upstream end 22a for collecting low-temperature cold fluid and a second downstream end 22b attached to the heat exchanger body 30, through which the cold fluid is injected into one or more channels of the heat exchanger body 30. The downstream cold fluid header 24 also extends between a first upstream end 24a, which is attached to the heat exchanger body 30, and a downstream end 24b, which communicates with a separate part of the turbine (not illustrated), through which the cold fluid that has circulated in the heat exchanger body 30 is recovered.

[0008] The heat exchanger body 30 (or exchanger core) is the part where the actual heat exchange between the hot fluid and the cold fluid occurs. It should therefore be understood that the heat exchanger body 30 comprises: one or more channels in which the hot fluid circulates, and one or more channels in which the cold fluid circulates, the heat transfer between the two fluids occurring through the walls of these different channels. In the case of a cross-flow exchanger, the channels in which the cold fluid circulates are perpendicular to the channels in which the hot fluid circulates, and these different channels can be superimposed on each other.

[0009] However, these heat exchangers are subject to considerable thermal loads. Thermal expansion / contraction of the exchanger's body (or core) 30 and headers occurs in every engine cycle, with considerable thermal transients being particularly associated with engine start-up and stop. These loads cause substantial restrictions in particular in the region of the junctions between the headers 12, 14, 22, 24 and the heat exchanger body 30. In particular, in the case of a cross-flow exchanger 1', there are four junction regions a, b, c, d between the downstream end 12b of the upstream hot fluid header 12, the downstream end 22b of the upstream cold fluid header 22 and the heat exchanger body 30, and between the upstream end 14a of the downstream hot fluid header 14, the upstream end 24a of the downstream cold fluid header 24 and the heat exchanger body 30. In the case of a heat exchanger having a rectangular cross-section header, these junction regions between the header ends and the heat exchanger body are straight contact lines.

[0010] These limitations may lead to the formation of cracks throughout the heat exchanger body / manifold, particularly in the joint areas a, b, c, d, through repeated thermal cycles. These cracks, known as thermal fatigue, may themselves lead to leaks and to component breakage, which significantly shortens the useful life of the exchanger. The mechanical properties of the manifold wall may also be impaired when the temperature of the hot fluid circulating in the manifold is greater than the permissible temperature of the wall (e.g. 100K for a wall made of stainless steel, or 500K for a wall made of aluminum).

[0011] On the contrary, it is obvious that the walls of the heat exchanger body 30 are less impacted. In fact, since the heat exchange between the hot fluid and the cold fluid mainly occurs in the heat exchanger body 30, the temperature of the walls in the exchanger body is between the temperature of the hot fluid and the temperature of the cold fluid.

[0012] One known solution consists in adding flexible sections or gussets to the headers, allowing for the extension and contraction of the header / heat exchanger body assembly. This reduces the stresses on the supports of the assembly and therefore reduces the risk of deformation of the exchanger. However, this type of device is difficult to implement in terms of operability and maintenance, is very costly and does not satisfactorily solve the above-mentioned problems related to the occurrence of cracks, particularly in the area of ​​the junction between the header and the heat exchanger body.

[0013] There is therefore a need for a heat exchanger arrangement which limits or even eliminates the problems associated with thermal fatigue on the one hand and with the mechanical strength of the headers on the other hand. Summary of the invention

[0014] The present disclosure relates to a heat exchanger device for an aircraft turbine, the heat exchanger device comprising: a heat exchanger body; an upstream hot fluid header, the upstream hot fluid header being attached to the heat exchanger body and being configured to collect a first fluid at a first temperature and supply the first fluid to the heat exchanger body; an upstream cold fluid header, the upstream cold fluid header being attached to the heat exchanger body and being configured to collect a second fluid at a second temperature lower than the first temperature and supply the second fluid to the heat exchanger body, at least the upstream hot fluid header comprising a double wall forming a peripheral cavity surrounding a main cavity, the main cavity being configured to receive a mainstream of the first fluid, the peripheral cavity being configured to receive a secondary flow of the first fluid or the second fluid.

[0015] In the present disclosure, the terms "upstream" and "downstream" are defined relative to the flow direction of the fluids in the different streams of the heat exchanger device, that is to say the "hot" stream and the "cold" stream. More specifically, the first fluid flows in the heat exchanger device according to its flow direction, from upstream to downstream, first in the upstream hot fluid header, then in the heat exchanger body and finally in the downstream hot fluid header defined later. In the same way, the second fluid flows from upstream to downstream, first in the upstream cold fluid header, then in the heat exchanger body and finally in the downstream cold fluid header defined later.

[0016] In the present disclosure, it should be understood that the double wall of the upstream hot fluid header includes two walls that are relatively close but not in contact with each other. The spacing between the two walls of such a double wall results in the formation of a peripheral cavity surrounding the main cavity. It is obvious that the main cavity transports the first fluid collected in the turbine to the heat exchanger body by means of a main flow.

[0017] In addition, a small portion of the first fluid or the second fluid may flow in the peripheral cavity, the small portion forming a secondary flow at the periphery of the main flow. Therefore, at ambient temperature, the first high-temperature fluid flowing into the main cavity is separated from the outside of the header by not a single wall but a double wall, by the peripheral cavity and by the secondary flow in the peripheral cavity.

[0018] This configuration reduces the heat transfer by distributing it in the two walls of the header and in the secondary flow, thus limiting the risk of cracks in these walls, in particular in the region of the junction between the upstream hot fluid header and the heat exchanger body.

[0019] In some embodiments, the device includes a downstream cold fluid header, which is attached to the heat exchanger body and is configured to collect the second fluid flowing out of the heat exchanger body, and the upstream hot fluid header is configured to: collect a small portion of the second fluid flowing into the upstream cold fluid header and supply the small portion to the downstream cold fluid header through the peripheral cavity.

[0020] According to this configuration, although most of the second fluid flows from upstream to downstream in the upstream cold fluid header, flows in the heat exchanger body, and then flows in the downstream cold fluid header, a small portion of the second fluid does not flow in the heat exchanger body but is diverted to the upstream hot fluid header, more specifically, flows in the peripheral cavity formed by the double walls of the upstream hot fluid header. Then, after flowing into the peripheral cavity, the small portion of the second fluid is re-injected into the downstream cold fluid header downstream of the heat exchanger body.

[0021] This second fluid flow is cooler than the first fluid in the peripheral cavity and therefore cools the wall locally on the side of the first fluid, in particular in the region of the joints between the header and the heat exchanger body, which are subject to particularly large thermal stresses. As a result, while the turbine is operating, the temperature of the upstream hot fluid header varies less, which effectively reduces or even eliminates the formation of cracks, while also increasing its mechanical strength. In this way, the double wall itself acts as a heat exchanger, which reheats this small portion of the second fluid and cools the wall of the upstream hot fluid header.

[0022] In some embodiments, the peripheral cavity includes: at least one inlet section opening in the main cavity of the upstream cold fluid header, the inlet section being configured to collect a small portion of the second fluid and being arranged at a first joint between the upstream cold fluid header, the upstream hot fluid header and the heat exchanger body.

[0023] It will be appreciated that the inlet section may be an opening formed in the junction between the upstream cold fluid header, the upstream hot fluid header and the heat exchanger body, placing the main cavity of the upstream cold fluid header in fluid communication with the peripheral cavity of the upstream hot fluid header. In this way, depending on the size of the inlet section, a small portion of the second fluid flowing into the upstream cold fluid header may enter the peripheral cavity of the upstream hot fluid header by means of the inlet section. Placing the inlet section in the region of the junction may facilitate heat exchange between the second fluid and the upstream hot fluid header wall at this location, limiting the risk of cracks at the junction.

[0024] In some embodiments, the peripheral cavity includes: at least one outlet section opening in the main cavity of the downstream cold fluid header, the outlet section being configured to inject the small portion of the second fluid flowing into the peripheral cavity into the downstream cold fluid header, and being arranged at a second joint between the downstream cold fluid header, the upstream hot fluid header and the heat exchanger body.

[0025] In the same way as the inlet section, it will be understood that the outlet section may be an opening formed in the junction between the upstream hot fluid header, the downstream cold fluid header and the heat exchanger body, placing the main cavity of the downstream cold fluid header in fluid communication with the peripheral cavity of the upstream hot fluid header. In this way, the small portion of the second fluid introduced via the inlet section and flowing into the peripheral cavity can be re-injected into the downstream cold fluid header through the outlet section. Arranging the outlet section in the region of this junction increases the heat exchange between the second fluid and the upstream hot fluid header wall at this location and thus limits the risk of cracks at this junction.

[0026] In some embodiments, the upstream hot fluid header and the downstream hot fluid header and the upstream cold fluid header and the downstream cold fluid header have rectangular cross-sections.

[0027] In this configuration, the first joint (and the second joint) between the upstream cold fluid header (and the downstream cold fluid header), the upstream hot fluid header and the heat exchanger body are linear joints, and the inlet section and the outlet section extend linearly over at least a portion of these joints.

[0028] As an alternative, the upstream hot fluid header and the downstream hot fluid header, as well as the upstream cold fluid header and the downstream cold fluid header have a circular cross-section, the first joint and the second joint extend in a circular arc shape, and the inlet section and the outlet section extend over an angular sector area of ​​20° to 180°.

[0029] Preferably, the inlet section and the outlet section are identical. Furthermore, the shape of the header is not limited, as other geometric shapes (eg elliptical) are also possible.

[0030] In some embodiments, the upstream hot fluid header comprises a wing portion which, on the one hand, extends longitudinally in the main cavity in the flow direction of the first fluid and, on the other hand, extends from one of the two walls of the double wall to the other of the two walls inside the peripheral cavity.

[0031] It will be understood that the wing is a wall extending vertically relative to one of the two walls of the double wall, in other words perpendicular to one of the two walls in the direction of the other of the two walls, but not in contact with the other wall. The wing also extends longitudinally, that is to say from upstream to downstream. It is obvious that preferably, these wings extend from the inner wall of the double wall. Since these wings are arranged in the peripheral cavity and are therefore immersed in the small part of the inflow of the second fluid into the cavity, they improve the heat transfer by increasing the exchange surface with the second fluid and therefore also reduce the wall temperature of the upstream hot fluid header.

[0032] In some embodiments, the wing extends longitudinally over a portion of the length of the upstream hot fluid header on the one hand and over the entire height of the space separating the two walls of the double wall on the other hand.

[0033] In contrast to the previous configuration, the wing extends over the entire height of the space separating the two walls of the double wall by contacting the two walls. This configuration also improves heat transfer by further increasing the exchange surface with the second fluid, thereby also reducing the wall temperature of the upstream hot fluid header.

[0034] In some embodiments, the wall of the downstream hot fluid header and the wall of the downstream cold fluid header include flexible sections configured to allow longitudinal deformation of the downstream hot fluid header and the longitudinal deformation of the downstream cold fluid header. The flexible sections may be gussets that may extend or retract in the manner of an accordion section of a straw to absorb expansion of the headers.

[0035] The flexible section allows extension and retraction of the header / heat exchanger body assembly.Thus, in addition to the advantages obtained by the double wall, the flexible section reduces the stress on the support of the assembly and therefore reduces the risk of deformation of the assembly.

[0036] In some embodiments, the upstream hot fluid header includes an intermediate wall disposed in the peripheral cavity and separating the small portion of the second fluid collected in the upstream cold fluid header into a secondary inner flow and a secondary outer flow.

[0037] In other words, the intermediate wall divides the peripheral cavity into two cavities, in which the secondary inner flow and the secondary outer flow circulate respectively. In the same way, the small portion of the second fluid collected in the upstream cold fluid header is divided into two flows, specifically, the secondary inner flow and the secondary outer flow.

[0038] Thus, it will be appreciated that the secondary internal flow occurs between the inner wall separating the peripheral cavity of the main cavity of the upstream thermal fluid header and the intermediate wall. In the same manner, the secondary external flow occurs between the outer wall separating the peripheral cavity outside the upstream thermal fluid header and the intermediate wall. Isolating a small portion of the collected second fluid improves the temperature uniformity of the upstream thermal fluid header wall and better distributes the heat transfer.

[0039] In some embodiments, the small portion of the second fluid collected in the upstream cold fluid header is between 0.5% and 5% of the flow rate of the second fluid flowing into the upstream cold fluid header.

[0040] As described above, these values ​​produce the effect of cooling the wall temperature of the upstream hot fluid header and limit any impact on the main flow of the second fluid used for heat transfer with the first fluid in the heat exchanger body.

[0041] In some embodiments, the device includes a downstream hot fluid header, which is attached to the heat exchanger body and is configured to collect the first fluid flowing out of the heat exchanger body. The downstream hot fluid header includes a double wall forming a peripheral cavity, and is configured to: collect a small portion of the second fluid flowing into the upstream cold fluid header, and supply the small portion to the downstream cold fluid header with the help of the peripheral cavity.

[0042] In this configuration, the upstream hot fluid header and the downstream fluid header each comprise a double wall, and a small portion of the second fluid is collected to flow in the cavity of each of these headers. Preferably, this small portion of the second fluid is diverted into the peripheral cavity of the downstream hot fluid header by means of an inlet section, and is re-injected into the downstream cold fluid header by means of an outlet section. For the downstream hot fluid header, the technical effects described above with reference to the upstream hot fluid header can also be obtained.

[0043] It is obvious that the fraction of the second fluid collected and diverted in the peripheral cavity of the downstream hot fluid header can be different from the fraction of the second fluid collected and diverted in the peripheral cavity of the upstream hot fluid header, so as to adapt the amount of the second fluid collected at the temperature of the downstream hot fluid header wall. In fact, since the downstream hot fluid header is located downstream of the heat exchanger body, the temperature of the first fluid flowing into the downstream hot fluid header located downstream of the heat exchanger body must necessarily present a lower temperature than its temperature when entering the upstream hot fluid header.

[0044] In some embodiments, the upstream thermal fluid header is configured to collect a small portion of the first fluid at an upstream end of the upstream thermal fluid header and supply the small portion to the heat exchanger body at a downstream end of the upstream thermal fluid header via the peripheral cavity.

[0045] In this configuration, in contrast to the above-described embodiment, the first fluid flows into the main cavity and the peripheral cavity at the same time and in the same circulation direction. In other words, the first fluid is separated into a main central flow and a secondary peripheral flow. This configuration makes the temperature change of the wall more gradual and thus reduces the thermal gradient. In particular, the peripheral flow in the double wall, which has a lower flow rate than the main flow, produces a lower exchange coefficient and thus a lower thermal gradient in the wall.

[0046] It is obvious that the upstream cold fluid header, the downstream hot fluid header and the downstream cold fluid header may also be provided with similar double walls which separate the respective flows into a primary core flow and a secondary peripheral flow.

[0047] In some embodiments, the double wall includes: an inner wall defining the main cavity, and an outer wall arranged around the inner wall, and a gap between the inner wall and the outer wall is between 1 mm and 10 mm.

[0048] The present disclosure also relates to an aircraft turbomachine comprising a heat exchanger arrangement according to any of the preceding embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] The invention and its advantages will be better understood from the following detailed description of different embodiments of the invention given as non-limiting examples. This description refers to the pages of the accompanying drawings, in which:

[0050] Figure 1 Schematically illustrates a cross-sectional elevation view of a cross-flow heat exchanger device according to the prior art,

[0051] Figure 2 Schematically illustrates a perspective view of a cross-flow heat exchanger device according to a first embodiment,

[0052] Figure 3 Schematically illustrates Figure 2 A cross-sectional elevation view of a heat exchanger device,

[0053] Figure 4 schematically illustrates a cross-sectional front view of a cross-flow heat exchanger arrangement according to a second embodiment,

[0054] Figure 5 schematically illustrates a cross-sectional front view of a cross-flow heat exchanger device according to a third embodiment,

[0055] Figure 6 schematically illustrates a cross-sectional front view of a cross-flow heat exchanger device according to a fourth embodiment,

[0056] Figure 7 schematically illustrates a cross-sectional front view of a cross-flow heat exchanger device according to a fifth embodiment,

[0057] Figure 8 A cross-sectional front view of a cross-flow heat exchanger arrangement according to a sixth embodiment is schematically illustrated. DETAILED DESCRIPTION

[0058] In the following of this disclosure, the terms "upstream" and "downstream" are defined relative to the direction of flow of fluids in the different streams (ie the "hot" stream and the "cold" stream) of the heat exchanger arrangement.

[0059] It is also obvious that for the sake of clarity and understanding, heat exchanger devices according to different embodiments are schematically illustrated, but details of the actual structure of such devices, such as the layout of the internal channels of the heat exchanger body 30, are not illustrated.

[0060] Figure 2 A perspective view of a heat exchanger device 1 according to a first embodiment of a cross-flow type is shown, and Figure 3 The front view and the cross-sectional view of the device are schematically illustrated, which includes a first flow 10 called "hot flow" and a second flow 20 called "cold flow". In addition, according to the present embodiment and the following embodiments, the headers 12, 14, 22, 24 are pipes with a rectangular cross section. However, it is obvious that the present invention is not limited to headers with a rectangular cross section and is also applicable to other forms, such as circular or elliptical.

[0061] It is also obvious that the invention is not limited to cross-flow exchanger devices, but is equally applicable to other types of exchangers, such as parallel-flow exchangers or counter-flow exchangers. Moreover, apart from the double wall described below, the other elements of the exchanger device 1 are the same as those previously described with reference to Figure 1 The exchanger device 1 ′ described is identical and will therefore not be repeated.

[0062] According to the present embodiment, the upstream hot fluid header 12 includes a double wall 120 . More specifically, the double wall 120 includes an inner wall 121 and an outer wall 122 surrounding the inner wall 121 .

[0063] The inner wall 121 defines a main chamber 125 in which a main flow of a first fluid (which is referred to as "hot fluid" in the following description) circulates from the upstream end 12a to the downstream end 12b of the upstream hot fluid header 12 so as to supply the hot fluid to the heat exchanger body 30. The outer wall 122 is arranged around the inner wall 121, for example, by being spaced apart from the inner wall 121 by a distance of 1 mm to 10 mm. Thus, a peripheral chamber 16 surrounding the main chamber 125 is formed between the inner wall 121 and the outer wall 122 of the double wall 120.

[0064] In addition, at the downstream end 12b attached to the heat exchanger body 30 and in the area of ​​the linear joint "a" between the upstream hot fluid header 12, the upstream cold fluid header 22 and the heat exchanger body 30, the upstream hot fluid header 12 includes an inlet section 16e, which connects the peripheral cavity 16 with the main cavity 225 fluid of the upstream cold fluid header 22, wherein a second fluid circulates in the upstream cold fluid header, which is referred to as "cold fluid" in the following description.

[0065] Furthermore, at the downstream end 12b attached to the heat exchanger body 30 and in the region of the linear junction “b” between the upstream hot fluid header 12, the downstream cold fluid header 24 and the heat exchanger body 30, the upstream hot fluid header 12 includes an outlet section 16s that fluidically connects the peripheral cavity 16 with the main cavity 245 of the downstream cold fluid header 24, wherein the cold fluid circulates in the downstream cold fluid header downstream of the heat exchanger body 30. It is also apparent that the peripheral cavity 16 is closed at the upstream end 12a of the upstream hot fluid header 12.

[0066] Preferably, the inlet section 16e has such a size that a portion P1 (which is between 0.5% and 5% of the main flow 20 of the cold fluid flowing into the upstream cold fluid header 22) is collected in the peripheral cavity 16. Thus, when it flows into the upstream cold fluid header 22, the portion P1 of the cold fluid (consisting of Figure 3 The heat exchanger body 30 will not enter the heat exchanger body 30, but will be diverted to the peripheral cavity 16.

[0067] Figure 3 The enlarged image at the bottom of the diagram schematically illustrates the trajectory (illustrated by arrows) of this portion P1 of the cold fluid in the peripheral cavity 16. Although the figure is illustrated in a plan view and the arrows indicate the longitudinal flow of the cold fluid in the peripheral cavity 16, it should be understood that the cold fluid not only flows longitudinally in one direction between the ends 12a and 12b and then in another direction, but also at the end of the upstream hot fluid header 12 (given the form of the peripheral cavity 16 (especially in the embodiment of the embodiment of the invention) Figure 2) flows around the main cavity 125. In this way, part P1 of the cold fluid is diffused in at least a part of the peripheral cavity 16 and then re-injected into the downstream cold fluid header 24 by means of the outlet section 16s.

[0068] It is obvious that the flow of the portion P1 of the cold fluid can be achieved by a set of pressure and temperature differences existing between the inlet section 16s and the outlet section 16e, in particular its collection via the inlet section 16e until it is reinjected into the downstream cold fluid header 24 via the outlet section 16s.

[0069] Furthermore, in this example, the downstream hot fluid header 14 further comprises a double wall 140 comprising an inner wall 141 and an outer wall 142, which together form a peripheral cavity 16. The peripheral cavity 16 is in fluid communication with the main cavity 225 of the upstream cold fluid header 22 via the inlet section 16e, and is in fluid communication with the main cavity 245 of the downstream cold fluid header 24 via the outlet section 16s.

[0070] The inlet section 16e is arranged to be in the area of ​​the linear joint “c” between the downstream hot fluid header 14, the upstream cold fluid header 22 and the heat exchanger body 30 at the upstream end 14a attached to the heat exchanger body 30, while the outlet section 16s is arranged to be in the area of ​​the linear joint “d” between the downstream hot fluid header 14, the downstream cold fluid header 24 and the heat exchanger body 30 at the upstream end 14a attached to the heat exchanger body 30.

[0071] Therefore, in this example, the portion P2 of the cold fluid (consisting of Figure 3 ) (which may also be the mainstream of the cold fluid between 0.5% and 5%) is collected and diverted to the peripheral cavity 16 of the downstream hot fluid header 14, which is the same as the upstream hot fluid header 12. It is obvious that the inlet section 16e and the outlet section 16s of the downstream hot fluid header 14 may be the same as the inlet section 16e and the outlet section 16s of the upstream hot fluid header 12, or may also be different from the latter.

[0072] In an example of application of the heat exchanger device 1, a hot fluid at a temperature of 1000°C (in particular, hot gases leaving the low-pressure turbine) can be collected at the inlet of the hot stream 10, while a cold fluid at a temperature of 100°C (for example, a cold fluid flowing in the secondary air flow path) can be collected at the inlet of the cold stream 20. In this case, the double walls 120, 140 of the hot fluid headers reduce the average temperature of their walls by 300°C to 500°C, the range depending on the heat exchange characteristics of each of the two fluids (hot and cold) in contact with the walls. In this way, due to the reduction in the wall temperature of the hot fluid headers 12, 14, during any given operation of the engine of the turbine, the walls of the hot fluid headers are subject to a smaller range of temperature variations.

[0073] In particular, without the double wall, the hot fluid header may be subjected to temperature variations between 20°C (ambient temperature before engine start) and 1000°C (temperature reached during engine operation). In the presence of the double wall, this range can be reduced to the difference [20°C - 500°C] by assuming that the maximum temperature of the inner wall 121, 141 drops by 500°C due to heat exchange with the cold fluid in the peripheral cavity 16. This therefore reduces the thermal load in the hot fluid header, especially in the area of ​​the most sensitive joints a, b, c and d, which reduces the risk of header deformation and leakage in the area of ​​these joints.

[0074] Figure 4 A heat exchanger device 1 according to a second embodiment is schematically illustrated. This heat exchanger device 1 differs from the heat exchanger device according to the first embodiment in that the upstream hot fluid header 12 comprises a plurality of wings 30 arranged in the peripheral cavity 16 .

[0075] like Figure 4 As illustrated in the lower left image of FIG. 1 , in which a cross section of the upstream hot fluid header 12 is represented in the cross-sectional view AA, the wing 30 is a wall extending vertically from and relative to the inner wall 121, for example, in other words, the wing is perpendicular to the inner wall 121 in the direction of the outer wall 122, but does not contact the inner wall 121. The wing 30 also extends longitudinally over at least part of the length of the upstream hot fluid header 12 between the upstream end 12a and the downstream end 12b, that is, from upstream to downstream. Preferably, the wing 30 is distributed around the central axis of the header at regular intervals.

[0076] These wings 30 are arranged in the peripheral cavity 16 by being immersed in a small portion of the cold fluid flowing into said cavity, which increases the exchange surface with the cold fluid and thus increases the heat transfer. It is obvious that the downstream hot fluid header 14, which in this example comprises a double wall 140, can also comprise similar wings 30 in its peripheral cavity.

[0077] Figure 5 A heat exchanger device 1 according to a third embodiment is schematically illustrated. Figure 5 As illustrated in the image at the lower left of , in which the cross section of the upstream hot fluid header 12 is represented in the cross-sectional view AA, the heat exchanger device 1 differs from the heat exchanger device according to the second embodiment in that the wing 30 extends over the entire height of the space separating the inner wall 121 and the outer wall 122.

[0078] In this configuration, the wing 30 extends longitudinally only over a portion of the length of the upstream hot fluid header 12 between the upstream end 12a and the downstream end 12b, rather than extending over the entire length of the upstream hot fluid header 12, so as to allow a small portion of the cold fluid collected by the inlet section 16e to flow in the peripheral cavity 16 to the outlet section 16s.

[0079] Figure 6 A heat exchanger device 1 according to a fourth embodiment is schematically illustrated. This heat exchanger device 1 differs from the heat exchanger device according to the first embodiment in that the downstream hot fluid header 14 and the downstream cold fluid header 24 include flexible sections 40. In this example, the flexible sections 40 are gussets that are arranged on sections of the headers 14, 24 and enable the headers to deform longitudinally by extending or retracting in order to absorb expansion of the headers.

[0080] Figure 7 A heat exchanger device 1 according to a fifth embodiment is schematically illustrated. This heat exchanger device 1 differs from the heat exchanger device according to the first embodiment in that the upstream hot fluid header 12 includes an intermediate wall 123, which is arranged in the peripheral cavity 16 and separates a small portion of the cold fluid collected in the upstream cold fluid header 22 into two small portions P11 and P12, thereby generating a secondary external flow and a secondary internal flow in the peripheral cavity 16.

[0081] More specifically, the intermediate wall 123 divides the peripheral cavity 16 into an outer peripheral cavity 161 in which the secondary external flow (i.e., a portion P11 of the cold fluid) circulates, and an inner peripheral cavity 162 in which the secondary internal flow (i.e., a portion P12 of the cooling fluid) circulates. To achieve this, the intermediate wall 123 extends around the inner wall 121 and transversely to the latter, thereby closing the inner peripheral cavity 162 at one of its ends. In other words, an end 123b of the intermediate wall 123 that opens to the side of the downstream end 12b of the header 12 is arranged between the inner wall 121 and the outer wall 122 so as to divide the inlet section 16e and the outlet section 16s into two parts, and an end 123a of the intermediate wall 123 that is close to the upstream end 12a of the header 12 is in contact with the inner wall 121 by being attached to the inner wall 121, thereby closing the inner peripheral cavity 162 at this end 123a.

[0082] In this example, the downstream hot fluid header 14 also comprises an intermediate wall 143 similar to the intermediate wall 123 , which is arranged between the inner wall 141 and the outer wall 142 and which separates the collected small portion P2 of the cold fluid into two portions P21 and P22 .

[0083] Figure 8 A heat exchanger device 1 according to a sixth embodiment is schematically illustrated. In this embodiment, in contrast to the previous embodiments, the peripheral cavity 16 is not closed but open at the upstream end 12a of the upstream hot fluid header 12. Furthermore, at the downstream end 12b, the peripheral cavity 16 does not end in the main cavity 225 of the upstream cold fluid header 22 but ends in the main cavity 125 of the upstream hot fluid header 12 opposite to the heat exchanger body 30. In this way, according to the present embodiment, the portion P1 of the main heat flow 10 is diverted in the peripheral cavity 16 in the region of the upstream end 12a and flows along the peripheral cavity 16 in the same circulation direction as the main flow in the main cavity 125 until the downstream end 12b.

[0084] This portion P1 of the main heat flow 10 then flows into the heat exchanger body 30. In this example, the downstream hot fluid header 14 also includes a double wall 140 similar to the double wall 120 of the upstream hot fluid header 12, which double wall 140 specifically includes an inner wall 141 and an outer wall 142. Therefore, the portion P1 of the main heat flow 10 leaving the heat exchanger body 30 can be diverted into the double wall 140 of the downstream hot fluid header 14.

[0085] Also in this example, the upstream cold fluid header 22 includes a double wall 220 having an inner wall 221 and an outer wall 222, and the downstream cold fluid header 24 includes a double wall 240 having an inner wall 241 and an outer wall 242. In this way, like the double walls of the upstream hot fluid header and the downstream hot fluid header, the portion P2 of the main cold flow 20 can be collected at the upstream end of the upstream cold fluid header 22, and can flow along the peripheral cavity of the upstream cold fluid header until the heat exchanger body 30, and then can be re-injected into the peripheral cavity of the downstream cold fluid header 24.

[0086] It is obvious that, unlike the previous embodiments in which the headers equipped with double walls are attached to the heat exchanger body 30 by means of their inner walls 121, 141, the headers of the heat exchanger device 1 according to the sixth embodiment are attached to the heat exchanger body 30 by means of their outer walls 122, 142, 222, 242. In this way, in the previous embodiments, the peripheral cavity 16 of the upstream hot fluid header 12 ends in the main cavity 225 of the upstream cold fluid header 22, while the peripheral cavity 16 of the upstream hot fluid header 12 according to the sixth embodiment ends in the heat exchanger body 30.

[0087] It is also obvious that in the aforementioned one to six different embodiments, the heat exchanger body 30 and different headers constituting the heat exchanger device 1 can be separate pieces assembled and connected to each other, for example by welding or brazing, or can be integrally manufactured, for example by additive manufacturing.

[0088] Although the present invention has been described with reference to specific exemplary embodiments, it is apparent that these examples may be modified and altered without departing from the general scope of the invention as defined in the claims. In particular, the various features of the different embodiments illustrated / mentioned may be combined into additional embodiments. Therefore, the present specification and drawings should be regarded as illustrative rather than restrictive.

Claims

1. A heat exchanger device (1) for an aircraft turbine, comprising: A heat exchanger body (30); an upstream thermal fluid header (12) attached to the heat exchanger body (30) and configured to collect a first fluid at a first temperature and supply the first fluid to the heat exchanger body (30); an upstream cold fluid header (22) attached to the heat exchanger body (30) and configured to collect a second fluid at a second temperature lower than the first temperature and supply the second fluid to the heat exchanger body (30), at least the upstream hot fluid header (12) comprising a double wall (120) forming a peripheral cavity (16) surrounding a main cavity (125), the main cavity being configured to receive a mainstream of the first fluid, the peripheral cavity (16) being configured to receive a secondary flow formed by a small portion of the first fluid or the second fluid.

2. The device (1) according to claim 1, comprising a downstream cold fluid header (24), which is attached to the heat exchanger body (30) and is configured to collect the second fluid flowing out of the heat exchanger body (30), the small portion being a small portion of the second fluid flowing into the upstream cold fluid header (22), and the upstream hot fluid header (12) being configured to: collect the small portion of the second fluid and supply the small portion to the downstream cold fluid header (24) through the peripheral cavity (16).

3. The device (1) according to claim 2, wherein: The peripheral cavity (16) includes: at least one inlet section (16e) opening in the main cavity (225) of the upstream cold fluid header (22), the inlet section (16e) being configured to collect the small portion of the second fluid and being arranged at a first joint (a) between the upstream cold fluid header (22), the upstream hot fluid header (12) and the heat exchanger body (30).

4. The device (1) according to claim 2 or 3, wherein: The peripheral cavity (16) comprises: at least one outlet section (16s) opening in the main cavity (245) of the downstream cold fluid header (24), the outlet section (16s) being configured to inject the small portion of the second fluid flowing into the peripheral cavity (16) into the downstream cold fluid header (24), and being arranged at a second joint (b) between the downstream cold fluid header (24), the upstream hot fluid header (12) and the heat exchanger body (30).

5. The device (1) according to any one of claims 1 to 4, wherein: The upstream hot fluid header (12) comprises a wing portion (30) which extends longitudinally in the main cavity (125) in the flow direction of the first fluid and extends from one of the two walls of the double wall (120) to the other of the two walls inside the peripheral cavity (16).

6. The device (1) according to claim 5, wherein: The wing (30) extends longitudinally over a portion of the length of the upstream hot fluid header (12) and over the entire height of the space separating the two walls (121, 122) of the double wall (120).

7. The device (1) according to any one of claims 1 to 4, wherein: The upstream hot fluid header (12) comprises an intermediate wall (123) which is arranged in the peripheral cavity (16) and separates the small portion of the second fluid collected in the upstream cold fluid header (22) into a secondary internal flow (162) and a secondary external flow (161).

8. The device (1) according to any one of claims 1 to 7, wherein: The small portion of the second fluid collected in the upstream cold fluid header (22) is between 0.5% and 5% of the flow rate of the second fluid flowing into the upstream cold fluid header (22).

9. The device (1) according to any one of claims 1 to 8, comprising a downstream hot fluid header (14), which is attached to the heat exchanger body (30) and is configured to collect the first fluid flowing out of the heat exchanger body (30), the downstream hot fluid header comprising a double wall (140) forming a peripheral cavity (16), and the downstream hot fluid header is configured to: collect a small portion of the second fluid flowing into the upstream cold fluid header (22) and supply the small portion to the downstream cold fluid header (24) through the peripheral cavity (16).

10. The device (1) according to claim 1, wherein: The small portion is a small portion of the first fluid, and the upstream thermal fluid header (12) is configured to collect the small portion of the first fluid at the upstream end (12a) of the upstream thermal fluid header (12), and supply the small portion to the heat exchanger body (30) at the downstream end (12b) of the upstream thermal fluid header (12) through the peripheral cavity (16).

11. The device (1) according to any one of claims 1 to 10, wherein: The double wall (120) includes: an inner wall (121) defining the main cavity (125); and an outer wall (122) arranged around the inner wall (121), and a gap between the inner wall (121) and the outer wall (122) is between 1 mm and 10 mm.

12. An aircraft turbine, comprising: Heat exchanger arrangement (1) according to any one of the preceding claims.

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