AIR-OIL HEAT EXCHANGER

Description

Domain

[0001] The invention relates to the field of turbomachinery heat exchangers. More specifically, the invention proposes an air / oil heat exchanger for an axial turbomachine. Previous art

[0002] In a turbomachine (turbojet), it is generally necessary to cool the oil in the lubrication circuit. For this purpose, it is known to place one or more heat exchangers in the secondary flow, that is to say, downstream of the fan.

[0003] However, the presence of a heat exchanger in the secondary circuit negatively impacts the overall performance and efficiency of the turbomachine. This is because the thrust generated by the fan is partially dampened by the bulky exchanger. Furthermore, aerodynamic disturbances in the secondary flow can occur, leading to vibrations and noise.

[0004] The published patent document EP 3 674 531 A1 discloses an air-oil heat exchanger located in the secondary flow stream of a turbomachine. Such a heat exchanger generates significant disturbances in the secondary flow, which has a velocity too high for aerodynamic or thrust losses to be negligible.

[0005] The published patent document US 10,502,502 A1 discloses a heat exchanger obtained by additive manufacturing and comprising smaller fluid passages.

[0006] The current state of the art therefore presents drawbacks related to performance penalties. Added to this is the constraint linked to the fragility of the heat exchanger. Indeed, it cannot be placed in a tertiary flow path radially between the primary and secondary flows. However, the risk of debris and foreign bodies entering the tertiary flow path is high, which can damage the heat exchanger. Summary of the invention Technical problem

[0007] The invention aims to provide a heat exchanger that minimizes aerodynamic losses caused by its placement in the airflow path. Furthermore, the invention also aims to improve heat exchange to ensure efficient cooling within a compact footprint without compromising turbomachine performance. Technical solution

[0008] The invention relates to an air / oil type heat exchanger for an annular air stream of a turbomachine, comprising a heat exchange zone with oil passages and heat exchange surfaces with the air, said heat exchange zone forming an axial air passage and having a profile facing the airflow and included in a plane perpendicular to said airflow, said profile of the heat exchange zone being in the shape of an arc of a circle so as to be able to be disposed in the annular air stream, remarkable in that said heat exchanger comprises on a radially internal or external face of the heat exchange zone, an oil inlet and an oil outlet, the oil passages comprising several paths between said oil inlet and said oil outlet, distributed along the arc of a circle profile of the heat exchange zone.

[0009] According to an advantageous embodiment of the invention, each of the paths comprises at least one outward portion and at least one return portion, extending radially between the radially inner face and the radially outer face of the heat exchange zone.

[0010] According to an advantageous embodiment of the invention, each outward portion and each return portion of each of the paths are offset along the arc-shaped profile of the heat exchange zone.

[0011] According to an advantageous embodiment of the invention, each of the paths comprises at least one connecting portion linking at least one outbound portion to at least one return portion and disposed in the heat exchange zone.

[0012] According to an advantageous embodiment of the invention, each of the outbound, return and connection portions of each of the paths extends over a total axial length of the heat exchange zone.

[0013] According to an advantageous embodiment of the invention, each path comprises several parallel oil passages distributed over the total axial length of the heat exchange zone.

[0014] According to an advantageous embodiment of the invention, each forward portion and each return portion of each of the paths comprises several parallel oil passages forming a doubly bent flow profile with a first radial part, a second axial part and a third radial part.

[0015] According to an advantageous embodiment of the invention, at least one connecting portion links together the first or third radial parts adjacent to said connecting portion.

[0016] According to an advantageous embodiment of the invention, the second axial parts of the forward and return portions have opposite flow directions.

[0017] According to an advantageous embodiment of the invention, the heat exchanger comprises on the radially internal face or the radially external face of the heat exchange zone comprising the oil inlet and the oil outlet, furthermore, a distributor arranged in a fluidic manner between the oil inlet and the paths and extending along the arc profile, and a collector arranged in a fluidic manner between the paths and the oil outlet and extending along the arc profile.

[0018] According to an advantageous embodiment of the invention, the oil inlet is at one end of the distributor along the arc profile and said distributor has a cross-section of said arc profile which gradually decreases along said arc profile from the oil inlet to an opposite end of said distributor.

[0019] According to an advantageous embodiment of the invention, the oil outlet is at one end of the collector following the arc-shaped profile and said collector has a cross-section of said arc-shaped profile which gradually decreases along said arc-shaped profile from the oil outlet to an opposite end of said collector.

[0020] According to an advantageous embodiment of the invention, the distributor and the collector are side-by-side along an axial extent of the radially internal or external face of the heat exchange zone comprising the oil inlet and the oil outlet.

[0021] According to an advantageous embodiment of the invention, the total radial height of the heat exchange zone increases from upstream to forward, and the axial air passage comprises air channels delimited by the heat exchange surfaces and having passage sections increasing from upstream to downstream in correspondence with the total radial height of the heat exchange zone.

[0022] According to an advantageous embodiment of the invention, the total radial height of the heat exchange zone and / or the cross-sections of the air channels increase from upstream to downstream over at least 70% of a total axial extent of said heat exchange zone.

[0023] According to an advantageous embodiment of the invention, the increase in the total radial height of the heat exchange zone and / or the increase in the cross-sections of the air channels is monotonic and / or of at least 30%.

[0024] According to an advantageous embodiment of the invention, the sections of the air channels have a polygonal shape, preferably hexagonal.

[0025] According to an advantageous embodiment of the invention, the heat exchange zone comprises radial walls distributed along the arc-shaped profile, and including the oil passages, the heat exchange surfaces being formed by transverse walls extending between the radial walls.

[0026] According to an advantageous embodiment of the invention, the air channels between each pair of adjacent radial walls form at least two radial rows of interlocking polygons, preferably hexagons.

[0027] According to an advantageous embodiment of the invention, the transverse walls are formed entirely with the forward portions or with the return portions.

[0028] According to an advantageous embodiment of the invention, the heat exchanger further comprises a wall with an arc-shaped profile parallel to, and radially at a distance from, the heat exchange zone so as to form, between said wall and said heat exchange zone, a bypass passage for air, parallel to the heat exchange passage.

[0029] According to an advantageous embodiment of the invention, the bypass passage, outside of radial and / or lateral limits of said bypass passage, is free of material.

[0030] According to an advantageous embodiment of the invention, the bypass passage has a section extending along the arc of a circle with a preferably constant radial height.

[0031] According to an advantageous embodiment of the invention, the bypass passage extends radially over a height between 10% and 20% of a cumulative radial height of said bypass passage and the heat exchange zone.

[0032] According to an advantageous embodiment of the invention, the bypass passage extends over a total extent of the heat exchanger along an airflow direction. Advantages of the invention

[0033] The invention is particularly advantageous in that it makes it possible to guarantee efficient heat exchange in a reduced space while avoiding hindering the performance of the engine, which results in energy efficiency and optimized thrust which advantageously reduces carbon dioxide emissions. Description of the drawings

[0034] [ Fig.1 ] is a partial perspective view of the exchanger according to a first embodiment; [ Fig. 2 ] illustrates a cross-sectional view of the heat exchanger according to a second embodiment; [ Fig.3 ] represents oil paths in the heat exchanger according to a third embodiment; [ Fig. 3a] illustrates a perspective view from below of the oil paths according to the third embodiment; [ Fig. 4 ] represents an oil path in the heat exchanger according to a fourth embodiment; [ Fig. 5 ] illustrates a cross-sectional view of the exchanger arranged in the annular air duct and according to the second embodiment; [ Fig. 6 ] represents an enlarged portion "A" of the heat exchange zone of the [ Fig. 2 ]. Description of a method of implementation

[0035] In the following description, the terms "internal" and "external" refer to positioning relative to the axis of rotation of a turbomachine. The axial direction corresponds to the direction along the axis of rotation of the turbomachine. The radial direction is perpendicular to the axis of rotation. Upstream and downstream refer to the direction of flow within the turbomachine.

[0036] The figures show the elements schematically and are not drawn to scale. In particular, some dimensions are enlarged to facilitate reading the figures.

[0037] There [ Fig.1 ] illustrates a partial perspective view of a heat exchanger 2 according to a first embodiment. It should be noted that a perspective view of the heat exchanger 2 is supposed to have an arc-shaped profile, however the [ Fig.1 [It has been greatly simplified to make it easier to understand.]

[0038] The heat exchanger 2 is of the air / oil type, configured to be mounted in an annular air stream of an axial turbomachine. Preferably, the axial turbomachine is a three-flow turbomachine, and the annular air stream is preferably a tertiary flow annular stream.

[0039] With reference to the [ Fig.1], the exchanger 2 includes a heat exchange zone 3 having oil passages 4 and heat exchange surfaces 6 forming a heat exchange passage for the air flow F.

[0040] Preferably, the heat exchanger 2 is a single-piece unit obtained by additive manufacturing, and more preferably obtained by laser melting on a bed of aluminum powder. For this purpose, the oil passages 4 are formed by tubular channels allowing oil circulation, and the heat exchange surfaces 6 are preferably formed by thin walls or plates, and advantageously, each plate delimits two heat exchange surfaces 6.

[0041] The heat exchange zone 3 is radially delimited by an upper wall 12 and by a lower wall 9, the oil passages extend radially and axially between said upper wall 12 and lower wall 9.

[0042] Indeed, the heat exchanger 2 of the present invention is of the "ACOC" type, an acronym for the English expression "Air-Cooled Oil Cooler", the latter is different from a surface air-oil exchanger "SACOC", in which the oil remains in the lower and upper walls and does not pass radially through the exchanger.

[0043] Advantageously, the heat exchange zone 3 has a profile facing the airflow and included in a plane perpendicular to said airflow, said profile of the heat exchange zone 3 being in the arc of a circle allowing the exchanger 2 to be able to be disposed in the annular air vein, in particular thanks to a wall 8 of the exchanger 2, called the inner wall 8 and which is located radially inside the heat exchange zone 3, so as to form a radially internal guide wall 8 of the annular air vein.

[0044] The inner wall 8 allows a bypass passage for air 10 to be formed which is parallel to the heat exchange passage between the inner wall 8 and the heat exchange zone 3.

[0045] In this configuration, the exchanger 2 includes an outer wall 12 radially and adjacent to the heat exchange zone 3, said outer wall 12 includes at least one upstream or downstream end a fixing flange 15 so as to be able to be fixed to an upstream or downstream casing of the annular air stream, the casing is preferably an external casing to the air flow F having the upstream and downstream parts fixed to the exchanger 2.

[0046] The bypass passage for air 10 is radially delimited by two radial limits having an arc-shaped profile and consisting of the inner wall 8 and a radial wall 9, the latter being the lower radial delimitation of the heat exchange zone 3.

[0047] The bypass passage for air 10 is free of matter between its two radial limits 8, 9 and / or its two lateral limits 11, one of which is not illustrated in the [ Fig.1 ] due to the cut made. The two lateral limits 11 are mainly perpendicular to the radial limits 8, 9, thus forming the bypass passage for the air 10 presenting a cross-section to the airflow F and which is rectangular curved following the arc profile.

[0048] The air bypass 10 is commonly called the air bypass 10, and may also be referred to as the "FOD" bypass, an acronym for "Foreign Object Debris." Indeed, the air bypass 10 extends longitudinally across the entire length of the heat exchanger 2; its main role is to allow debris contained in the airflow F to pass through the annular channel of the turbomachine. This debris, or "FOD," can include, for example, birds, hail, hailstones, or any other object that could obstruct or damage the heat exchanger.

[0049] In parallel with the air bypass 10, a protective grid can be placed on a front face of the exchanger 2 to further protect the oil passages 4 and the exchange surfaces 6, without hindering their heat exchange capacity.

[0050] The air bypass 10 extends radially over a height h between 10% and 20% of a cumulative radial height H of said bypass passage and the heat exchange zone. Preferably, the height of the air bypass 10 extends radially to a maximum of 15% of the cumulative radial height H.

[0051] The radial height h of the air bypass 10 is constant over the total extent of the exchanger 2 following the airflow F. Indeed, the height h does not change at all with the airflow because it is not desired to modify the speed of the air, only the passage of debris is expected from the air bypass 10. However, the height h may have a small variation of at most 1% of the value h, which may be related to manufacturing precision.

[0052] Advantageously, the constant height h allows the difference in pressure loss between the air bypass 10 and the heat exchange zone 3 to be limited. However, the radial height h of the air bypass 10 can vary slightly in order to compensate for possible pressure losses that may be caused by aerodynamic disturbances downstream of the exchanger 2. In this respect, the air bypass 10 can have a convergent and / or divergent longitudinal section.

[0053] According to the first embodiment illustrated in the [ Fig.1 ], the heat exchange zone 3 is radially delimited by a radially internal face 14 belonging to the radial wall 9, and a radially external face 16 belonging to the external wall 12.

[0054] Preferably, the exchanger 2 includes an oil inlet and an oil outlet on the radially internal face 14.

[0055] The oil passages 4 comprise several paths between an oil inlet and an oil outlet, said paths extending radially outwards to the radially internal face 14, and which are distributed along the arc-shaped profile of the heat exchange zone 3.

[0056] The heat exchange zone 3 may include a circumferential divergence in its downstream part, i.e. the circumferential section of the heat exchange zone 3 increases from upstream to downstream, allowing the oil passages 4 to be distributed circumferentially in the exchanger 2 between the oil inlet and the oil outlet while avoiding crossing the air bypass.

[0057] There [ Fig. 2 ] illustrates a cross-sectional view of the exchanger 2 according to a second embodiment, schematically illustrating the oil paths.

[0058] Indeed, the second embodiment consists of positioning the air bypass 10 in a radially elevated position such that said air bypass 10 is adjacent to the external casing of the turbomachine. Whereas the first embodiment consists of positioning the air bypass 10, having the same geometric configuration as described above, as being adjacent to an internal casing of the turbomachine.

[0059] In this regard, and with reference to the [ Fig. 2 ], the exchanger 2 includes an outer wall 12' located radially outside the heat exchange zone 3, so as to form a radially external guide wall for the annular air stream.

[0060] Similar to the outer wall 12 of the [ Fig.1 ], the outer wall 12' of the [ Fig. 2 ] may also include a mounting flange to attach the heat exchanger to an external housing of the turbomachine.

[0061] In this configuration, the air bypass 10 is radially delimited by two radial limits consisting of the outer wall 12' and a radial wall 9' which radially delimits the heat exchange zone 3 externally. For this purpose, the radial height h of the air bypass 10 is between the radial wall 9' and the outer wall 12.

[0062] The exchanger 2 further comprises an inner wall 8', arranged radially internally and adjacent to the heat exchange zone 3. For this purpose, the inner wall 8' comprises at least one upstream or downstream or circumferential end, a fixing flange so as to be able to be fixed to an upstream or downstream housing of the annular air stream, said housing is preferably an internal housing to the airflow having the upstream and downstream parts fixed to the exchanger 2.

[0063] In this configuration, the exchanger 2 is configured to be an integral part of the internal and external casings of the turbomachine and to ensure aerodynamic continuity of the annular air stream.

[0064] Advantageously, the exchanger 2 can be manufactured and adapted according to the architecture of the turbomachine in which it will be mounted in order to anticipate the radial part of the annular air stream which includes the greatest risk of impact with the debris "FOD" so that the air bypass 10 is arranged there.

[0065] There [ Fig. 2 ] also illustrates the heat exchange zone 3 as being radially delimited by a radially internal face 14' belonging to the inner wall 8', and a radially external face 16' belonging to the radial wall 9'.

[0066] Preferably, the heat exchanger 2 includes an oil inlet 18 and an oil outlet 20 on the radially internal face 14'. However, the heat exchanger 2 may include the oil inlet and outlet 18, 20 on the radially external face 16'.

[0067] The oil passages 4 comprise several paths 22 between the oil inlet 18 and the oil outlet 20 and which are distributed along the arc-shaped profile of the heat exchange zone 3. The exchanger 2 may comprise a single oil path or it may comprise several paths up to 10 oil paths.

[0068] Each of the oil passages 22 comprises at least one forward portion 26 and at least one return portion 28. The terms "forward" and "return" refer to the principal radial flow direction of the oil in the oil passages 4. In this respect, the forward portion 26 corresponds to a portion of the oil passage 22 in which the oil flows radially from bottom to top. Similarly, the return portion 28 corresponds to a portion of the oil passage 22 in which the oil flows radially from top to bottom.

[0069] The two forward and return portions 26 and 28 are offset along the arc-shaped profile of the heat exchange zone 3, and extend radially between the radially inner face 14' and the radially outer face 16' of the heat exchange zone. Furthermore, each of the paths 22 includes at least one connecting portion 30 linking at least one forward portion 26 to at least one return portion 28.

[0070] Advantageously, as can be seen on the [ Fig. 2 The circumferential offset along the arc-shaped profile of the heat exchange zone 3, provided by the connecting portion 30 between the supply portion 26 and the return portion 28, allows for a circumferential increase in the oil's path within the exchanger. As a result, the airflow is perpendicular to the oil's path, and heat exchange is maximized.

[0071] The radially internal face 14' further includes a distributor 32 arranged in a fluidic manner between the oil inlet 18 and the paths 22 and extending along the arc profile, and a collector 34 arranged in a fluidic manner between the paths 22 and the oil outlet 20 and extending along the arc profile.

[0072] The oil inlet 18 is at one end of the distributor 32 following the arc profile and having a cross-section of said arc profile which gradually decreases along the latter from the oil inlet 18 to an opposite end of the distributor 32.

[0073] Similarly, the oil outlet 20 is at one end of the manifold 34 following the arc-shaped profile and having a cross-section of said arc-shaped profile which gradually decreases along the latter from the oil outlet 20 to an opposite end of the manifold 34.

[0074] Preferably, the distributor 32 and the collector 34 are side-by-side along an axial extent of the radially internal face 14' of the heat exchange zone 3.

[0075] The present invention presents two different variations concerning the oil paths. The third and fourth embodiments described below relate to variations of the oil path, it being understood that each of these third and fourth embodiments can be applied to either the first or the second mode. Indeed, one can choose a high or low radial position for the air bypass and simultaneously define the desired oil path embodiment.

[0076] There [ Fig.3 ] illustrates the oil paths 22 as described previously, in the exchanger according to the third embodiment, and in which each of the forward 26, return 28 and connection 30 portions of each of the paths 22 extend over a total axial length of the heat exchange zone.

[0077] Each path 22 comprises several parallel oil passages 4 distributed along the total axial length of the heat exchange zone. More precisely, the oil passages 4 extend axially over the majority of the axial length of the heat exchange surfaces. Preferably, the number of oil passages 4 is between 5 and 30, and more preferably, between 10 and 25.

[0078] There [ Fig. 3a ] illustrates a perspective view from below of the oil paths of the [ Fig.3 ] which are according to the third embodiment of the invention.

[0079] For this purpose, the distributor 32 supplies the oil passages 4 which are included in the forward portions 26, and the connection between the distributor 32 and said forward portions 26 is made by means of an oil inlet passage 33.

[0080] Preferably, each oil inlet passage 33 is an integral part of the oil passages 4, and includes a cross-section F that gradually decreases along the airflow.

[0081] Advantageously, reducing the cross-section of the oil inlet passage 33 helps to reduce pressure losses.

[0082] Similarly, the collector 34 allows the oil exiting the oil passages 4 which are included in the return portions 28 to be recovered by means of an oil outlet passage 35.

[0083] There [ Fig. 4 ] represents an oil path 22' in the heat exchanger according to a fourth embodiment. Preferably, the heat exchanger comprises a plurality of oil paths similar to the oil path 22'.

[0084] The oil path 22' comprises several oil passages 4' which are formed by parallel tubular channels and forming a forward portion 26' and a return portion 28'. Each of the forward portion 26' and return portion 28' forms an oil flow profile which is doubly bent with a first radial part 36, a second axial part 38 and a third radial part 40.

[0085] The exchanger according to the fourth embodiment can include a plurality of oil paths 22'. In this respect, each oil path 22' can be directly linked to the distributor 32' and the manifold 34' as well as to the oil inlet passages 33' and the oil outlet passages 35' which are identical to those described previously for the third embodiment.

[0086] In the direction of oil flow, i.e. from the oil inlet passage 33 to the oil outlet passage 35, the supply sections 26' and the return sections 28' are connected to each other via a connecting portion 30'. Specifically, said connecting portion 30' allows for the connection of two third radial sections 40, one belonging to the supply section 26' and the other to the return section 28'.

[0087] Similarly and in the same direction of oil flow, the return parts 28' are connected to the forward parts 26' by means of the connecting portion (not illustrated in the [ Fig. 4 ]). Specifically, the said connection portion allows to connect two first radial parts 36 each being belonging to the return part 28' and the other to the going part 26'.

[0088] There [ Fig. 4[Illustrates a single 28' return section; however, each 22' oil path can include several 28' return sections and several 26' forward sections. Preferably, the 22' oil path includes two 26' forward sections and two 28' return sections.]

[0089] The second axial sections of the forward 26' and return 28' portions have opposite flow directions. For this purpose, the second axial section 38 of the return 28' portion includes the oil which is in a first axial flow direction opposite to the second axial section 38 of the forward 26' portion, the flow direction of the latter being particularly opposite to the air flow F.

[0090] In this configuration, the heat exchange between the oil passages 4' and the air is partially counter-current. Advantageously, this allows for more efficient convective heat exchange between the oil passages 4' and the airflow F, effectively minimizing the length of the oil path in the oil passages 4' of the heat exchanger, thereby reducing the size and weight of the heat exchanger within the turbomachine.

[0091] Preferably, the fourth embodiment of the invention is used when the total axial extent of the heat exchange zone is greater than its total radial extent. Advantageously, this maximizes heat exchange in counter-current flow with the airflow.

[0092] The exchanger of the invention has a heat exchange zone that is preferentially divergent in the radial direction and along the direction of the airflow.

[0093] Advantageously, the divergence of the heat exchange zone helps to limit pressure losses within the exchanger and to improve heat exchange between the air and the oil flowing through the oil passages 4'.

[0094] There [ Fig. 5 ] illustrates a cross-sectional view of the exchanger 2 according to the second embodiment, the exchanger 2 being arranged in the annular air duct.

[0095] The oil passages 4' illustrated in the [ Fig. 5 ] belong to the fourth embodiment of the invention. However, the divergence of the exchanger 2 is not limited to this last embodiment in particular, and the oil passages 4 illustrated in figures 3 and 3a representing the third embodiment can also be used in the [ Fig. 5 ].

[0096] With reference to the [ Fig. 5], the total radial height Z of the heat exchange zone 3 increases from upstream to forward, and the axial air passage includes air channels 5 delimited by the heat exchange surfaces 6 and having passage sections increasing from upstream to downstream in correspondence with the total radial height Z of the heat exchange zone 3.

[0097] The total radial height Z of the heat exchange zone 3 and / or the cross-sections of the air channels 5 increase from upstream to downstream over at least 70% of a total axial extent of said heat exchange zone 3. Preferably, the cross-sections of the air channels 5 increase from upstream to downstream over the entire total axial extent of the heat exchange zone 3.

[0098] The increase in the total radial height Z of the heat exchange zone 3 and / or the increase in the cross-sections of the air channels 5 is monotonic and / or of at least 30%. Preferably, the increase in the cross-sections of the air channels 5 is monotonic and of at least 50%.

[0099] Preferably, the exchanger 2 comprises several angular sectors, each angular sector comprising the oil inlet 18 and the oil outlet, said oil inlet and / or said oil outlet being fully formed in the inner wall, and at least one of the sectors comprises a bypass passage (not illustrated) of said sector, also called an oil bypass, extending fluidically between the oil inlet 18 and the oil outlet along the inner wall.

[0100] Advantageously, the oil bypass ensures the cold operation of the exchanger 2, particularly at temperatures approaching -40°C. Indeed, cold oil has a high viscosity which is not suitable for passing through the exchanger 2; therefore, the oil passes through the oil bypass until it reaches a suitable viscosity.

[0101] In this regard, another circuit called the defrosting circuit (not illustrated) can be arranged near or in contact with the oil bypass, and can also be in contact with the oil passages 4', the defrosting circuit can ensure the heating of the oil included in the exchanger 2.

[0102] The oil bypass includes a normally closed valve that opens when there is a pressure difference between the oil inlet 18 and the oil outlet that exceeds a specified limit. The valve can also open when the oil viscosity exceeds a predetermined threshold.

[0103] There [ Fig. 6 ] represents an enlarged portion A of the heat exchange zone identified in the [ Fig. 2 ].

[0104] The enlarged portion A is slightly in perspective to facilitate its description and shows the oil passages 4 according to the third embodiment of the invention or the oil passages 4' according to the fourth embodiment.

[0105] The air channels 5 are delimited by the exchange surfaces 6 and the supply portion 26, 26' or the return portion 28, 28'. The cross-sections of the air channels 5 have a polygonal and preferably pentagonal shape. More preferably, each air channel 5 is delimited by four plates having four exchange surfaces 6 and a supply portion 26, 26' or a return portion 28, 28' and two of the four exchange surfaces 6 belonging to transverse plates integrally formed with the oil passages 4, 4' of the supply portions 26, 26' or the return portions 28, 28'.

[0106] For this purpose, the oil passages 4, 4' can be formed by a recess of material in a plate or panel, and the forward and return portions can be included in a radial panel.

[0107] The air channels 5 between each pair of adjacent forward sections 26, 26' and return sections 28, 28' form at least two radial rows 42, 44 of interlocking polygons, preferably pentagons. The number of radial rows 42, 44 may depend on the circumferential distance between the forward section 26, 26' and the return section 28, 28'.

[0108] The heat exchange zone further includes edge plates 7 having exchange surfaces 6, indeed the edge plates 7 are similar to the plates having exchange surfaces 6 of the heat exchange zone.

[0109] Advantageously, the edge plates 7 ensure heat exchange at the edges of the heat exchange zone while generating a constant pressure drop relative to the rest of said heat exchange zone, this minimizes aerodynamic disturbances of the airflow in the annular vein.

[0110] The heat exchanger of the invention, according to any of the embodiments described above, can extend continuously over 360° within a section of the annular air stream around the longitudinal axis of the turbomachine. Preferably, the heat exchanger extends discontinuously over 360° around the longitudinal axis by subdividing into several angular segments, and each heat exchanger can perform a heat exchange function between the air and the oil, which may differ from one segment to another.

[0111] Indeed, each can combine the cooling of several functions or oil circuits of the turbomachine, and this according to different parameters related to the need for oil cooling, i.e. inlet temperatures, flow rates, required outlet temperature or air conditions, the different circuits can be thermally connected or isolated.

[0112] In this regard, the heat exchanger can provide cooling for the oil used in several aircraft components, including an engine, a gearbox, a generator, and any electronic component requiring cooling.

[0113] Advantageously, the heat exchanger and in particular the oil passages can withstand a low oil temperature of up to -54°C, and at the same time withstand a high oil temperature of up to 180°C with a flow rate of up to 30000 l / h.

[0114] It should be noted that the invention is not limited to the examples shown in the figures. The principles of the present invention may, in particular, be applicable to other types of turbomachinery.

[0115] Each technical feature of each illustrated example is applicable to the other examples. In particular, the combination of the third or fourth embodiment with the first or second embodiment.

Claims

1. A heat exchanger (2) of the air / oil type for an annular air vein of a turbomachine, comprising a heat exchange zone (3) with oil passages (4, 4') and heat exchange surfaces (6) with the air, said heat exchange zone (3) forming an axial air passage and having an arcuate profile relative to the air flow (F) and lying in a plane perpendicular to said air flow (F), said profile of the heat exchange zone (3) being arcuate in order to be disposed in the annular air vein, said heat exchanger (2) comprising, on a radially internal face (14, 14') or external face (16, 16') of the heat exchange zone (3), an oil inlet (18) and an oil outlet (20), the oil passages (4, 4') comprising several paths (22, 22') between said oil inlet (18) and said oil outlet (20), distributed along the arcuate profile of the heat exchange zone (3), each of the paths (22, 22') comprising at least one forward portion (26, 26') and at least one return portion (28, 28'), extending radially between the radially internal face (14, 14') and the radially external face (16, 16'), said heat exchanger being characterized in that each forward portion (26, 26') and each return portion (28, 28') of each of the paths (22, 22') are offset along the arcuate profile of the heat exchange zone (3).

2. The heat exchanger (2) according to claim 1, characterized in that each of the paths (22, 22') comprises at least one connection portion (30, 30') connecting the at least one forward portion (26, 26') to the at least one return portion (28, 28') and disposed in the heat exchange zone (3).

3. The heat exchanger (2) according to any one of claims 1 and 2, characterized in that each of the forward portions (26), return portions (28), and connection portions (30) of each of the paths (22) extends over a total axial length of the heat exchange zone (3).

4. The heat exchanger (2) according to claim 3, characterized in that each path (22) comprises several parallel oil passages (4) distributed over the total axial length of the heat exchange zone (3).

5. The heat exchanger (2) according to any one of claims 1 and 2, characterized in that each forward portion (26') and each return portion (28') of each of the paths (22') comprises several parallel oil passages (4') forming a double-bent flow profile with a first radial part (36), a second axial part (38), and a third radial part (40).

6. The heat exchanger (2) according to claims 2 and 5, characterized in that the at least one connection portion (30') connects together adjacent first radial parts (36) or third radial parts (40) adjacent to said connection portion (30').

7. The heat exchanger (2) according to any one of claims 5 and 6, characterized in that the second axial parts (38) of the forward portions (26') and return portions (28') have opposite flow directions.

8. The heat exchanger (2) according to any one of claims 1 to 7, comprising on the radially internal face (14, 14') or the radially external face (16, 16') of the heat exchange zone (3) comprising the oil inlet (18) and the oil outlet (20), further comprising a distributor (32) fluidically disposed between the oil inlet (18) and the paths (22, 22') and extending along the arcuate profile, and a collector (34) fluidically disposed between the paths (22, 22') and the oil outlet (20) and extending along the arcuate profile, and preferably the oil inlet (18) is at one end of the distributor (32) following the arcuate profile, and said distributor presents a transverse passage cross-section relative to said arcuate profile which progressively decreases along said arcuate profile from the oil inlet (18) to an opposite end of said distributor (32).

9. The heat exchanger (2) according to claim 8, characterized in that the oil outlet (20) is at one end of the collector (34) following the arcuate profile, and said collector (34) presents a transverse passage cross-section relative to said arcuate profile which progressively decreases along said arcuate profile from the oil outlet (20) to an opposite end of said collector (34).

10. The heat exchanger (2) according to any one of claims 8 and 9, characterized in that the distributor (32) and the collector (34) are side-by-side following an axial extent of the radially internal face (14, 14') or external face (16, 16') of the heat exchange zone (3) comprising the oil inlet (18) and the oil outlet (20).

11. The heat exchanger (2) according to any one of claims 1 to 10, characterized in that the total radial height (Z) of the heat exchange zone (3) increases from upstream to downstream, and the axial air passage comprises air channels (5) delimited by the heat exchange surfaces (6) and presenting passage sections increasing from upstream to downstream in correspondence with the total radial height (Z) of the heat exchange zone (3), and preferably the total radial height (Z) of the heat exchange zone (3) and / or the sections of the air channels (5) increase from upstream to downstream over at least 70% of a total axial extent of said heat exchange zone (3).

12. The heat exchanger (2) according to claim 11, characterized in that the increase of the total radial height (Z) of the heat exchange zone (3) and / or the increase of the sections of the air channels (5) is monotonic and / or at least 30%.

13. The heat exchanger (2) according to one of claims 11 and 12, characterized in that the sections of the air channels (5) have a polygonal shape, preferably pentagonal.

14. The heat exchanger (2) according to one of claims 1 to 13, characterized in that the heat exchange zone (3) includes the forward portions (26, 26') and return portions (28, 28') extending radially and distributed along the arcuate profile, and including the heat exchange surfaces (6) formed by transverse walls extending between the forward portions (26, 26') and / or the return portions (28, 28') and preferably the air channels (5) between each pair of neighboring forward portions (26, 26') and return portions (28, 28') form at least two radial rows of polygons, preferably pentagons, nested together.

15. The heat exchanger (2) according to claim 14, characterized in that the transverse walls are integrally formed with the forward portions (26, 26') or with the return portions (28, 28').