BE1030019A1 - AIR-OIL HEAT EXCHANGER - Google Patents

Abstract

Heat exchanger (2) of the air/oil type, for an annular air stream of a turbomachine, comprising a heat exchange zone (3) with oil passages (4) and heat exchange surfaces with the air, said heat exchange zone forming an axial air passage and having a profile facing the air flow and included in a plane perpendicular to said air flow, said profile of the exchange zone being in an arc of a circle so as to be able to be placed in the annular air stream, remarkable in that said heat exchanger comprises on a radially internal (14') or external (16') face of the exchange zone thermal, an oil inlet (18) and an oil outlet (20), the oil passages comprising several paths (22) between said oil inlet and said oil outlet, distributed along the profile in arc of a circle of the heat exchange zone.

Description

Description

AIR-OIL HEAT EXCHANGER

Domain

The invention relates to the field of turbomachine heat exchangers.

More specifically, the invention provides an axial turbomachine air/oil heat exchanger.

Prior art

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 exchanger(s) in the secondary flow, that is to say downstream of the fan.

However, the provision of a heat exchanger at the level of the secondary circuit penalizes the performance and the overall efficiency of the turbomachine. Indeed, the thrust force generated by the fan is partly slowed down by the bulky heat exchanger. In addition, aerodynamic disturbances of the secondary flow can take place causing vibrations and noise pollution.

The published patent document EP 3 674 531 A1 discloses an air-oil type heat exchanger arranged in the side stream of a turbomachine. Such a heat exchanger generates significant disturbances to the secondary flow having too high a speed for the aerodynamic or thrust losses to be negligible.

The state of the art therefore has drawbacks relating to performance penalties. To which is added the constraint linked to the fragility of the exchanger. In fact, it cannot be placed in a tertiary flow stream lying radially between the primary flow and the secondary flow. However, the risk of passing debris and foreign bodies into the tertiary flow stream is high, which can damage the heat exchanger.

Summary of the invention

Technical problem

The aim of the invention is to propose a heat exchanger which minimizes the aerodynamic losses induced by the presence of the exchanger in the vein of the air flow. Also, the invention also aims to improve the heat exchange in order to guarantee effective cooling in a restricted space without hindering the efficiency of the turbomachine.

Technical solution

The invention relates to a heat exchanger of the air/oil type, 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 air flow and included in a plane perpendicular to said air flow, said profile of the heat exchange zone being in an arc of a circle so as to be able to be placed in the annular air stream, noteworthy in that said heat exchanger comprises, on a radially internal or external face of the heat exchange zone, an oil inlet and an outlet oil, the oil passages comprising several paths between said oil inlet and said oil outlet, distributed along the arcuate profile of the heat exchange zone.

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.

According to an advantageous embodiment of the invention, each outward portion and each return portion of each of the paths are offset along the arcuate profile of the heat exchange zone.

According to an advantageous embodiment of the invention, each of the paths comprises at least one connection portion connecting the at least one outward portion to at least one return portion and arranged in the heat exchange zone.

According to an advantageous embodiment of the invention, each of the outward, return and connection portions of each of the paths extend over a total axial length of the heat exchange zone.

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.

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 .

According to an advantageous embodiment of the invention, the at least one connection portion interconnects the first or third radial portions adjacent to said connection portion.

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

According to an advantageous embodiment of the invention, the heat exchanger comprises on the radially inner face or the radially outer face of the heat exchange zone comprising the oil inlet and the oil outlet, in addition, a distributor fluidly disposed between the oil inlet and the paths and extending along the arcuate profile, and a manifold fluidly disposed between the paths and the oil outlet and extending along of the circular arc profile.

According to an advantageous embodiment of the invention, the oil inlet is at one end of the distributor following the arcuate profile and said distributor has a section of passage transverse to said arcuate profile which gradually decreases along said profile. in an arc from the oil inlet to an opposite end of said distributor.

According to an advantageous embodiment of the invention, the oil outlet is at one end of the manifold following the arcuate profile and said manifold has a section of passage transverse to said arcuate profile which gradually decreases along said profile in arc of a circle from the oil outlet to an opposite end of said manifold.

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. oil.

According to an advantageous embodiment of the invention, the total radial height of the heat exchange zone increases from upstream to front, 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.

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

According to an advantageous mode of the invention, the increase in the total radial height of the heat exchange zone and/or the increase in the sections of the air channels is monotonous and/or by at least 30%.

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

According to an advantageous embodiment of the invention, the heat exchange zone comprises radial walls distributed along the arcuate profile, and comprising the oil passages, the heat exchange surfaces being formed by transverse walls s extending between the radial walls.

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 nested polygons, preferably hexagons.

According to an advantageous embodiment of the invention, the transverse walls are integrally formed with the forward portions or with the return portions.

According to an advantageous embodiment of the invention, the heat exchanger further comprises a wall with an arcuate 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 the air, parallel to the heat exchange passage.

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

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

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

According to an advantageous mode of the invention, the bypass passage extends over a total extent of the heat exchanger in an air flow direction.

Advantages of the invention

The invention is particularly advantageous in that it makes it possible to guarantee effective heat exchange in a reduced space while avoiding hindering the efficiency of the engine, which results in energy efficiency and optimized thrust which advantageously makes it possible to reduce the carbon dioxide emissions.

Description of the drawings

Figure 1 is a partial perspective view of the exchanger according to a first embodiment;

Figure 2 illustrates a sectional view of the exchanger according to a second embodiment;

FIG. 3 represents oil paths in the exchanger according to a third embodiment;

Figure 3a illustrates a bottom perspective view of the oil paths according to the third embodiment;

FIG. 4 represents an oil path in the exchanger according to a fourth embodiment;

Figure 5 illustrates a sectional view of the heat exchanger arranged in the annular air stream ... and according to the second embodiment;

Figure 6 shows an enlarged portion "A" of the heat exchange zone of Figure 2.

Description of an embodiment

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 flow direction of a stream in the turbomachine.

The figures show the elements schematically and are not drawn to scale. In particular, certain dimensions are enlarged to facilitate reading of the figures.

Figure 1 illustrates partial perspective view of a heat exchanger 2 according to a first embodiment. Note that a perspective view of heat exchanger 2 is assumed to have an arcuate profile, however Figure 1 has been greatly simplified to aid understanding.

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 an annular tertiary flow stream.

Referring to Figure 1, the exchanger 2 comprises a heat exchange zone 3 having oil passages 4 and heat exchange surfaces 6 forming a heat exchange passage for the air flow F.

Preferably, the exchanger 2 is a one-piece part obtained by additive manufacturing, and more preferably obtained by laser fusion on a bed of aluminum powder. To this end, the oil passages 4 are formed by tubular channels allowing the circulation of oil and the exchange surfaces 6 are preferably formed by thin walls or plates, and advantageously, each plate delimits two surfaces of exchange 6.

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.

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 cross the exchanger radially.

Advantageously, the heat exchange zone 3 has a profile facing the air flow and included in a plane perpendicular to said air flow, said profile of the heat exchange zone 3 being in an arc of a circle allowing the exchanger 2 to be able to be arranged in the annular air stream, 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 inner guide wall 8 of the annular air stream.

The inner wall 8 makes it possible to form a bypass passage for the air 10 which is parallel to the heat exchange passage between the inner wall 8 and the heat exchange zone 3.

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

The by-pass passage for the air 10 is delimited radially by two radial limits having an arcuate profile and made up of the inner wall 8 and a radial wall 9, the latter being the lower radial delimitation of the zone of heat exchange 3.

The bypass passage for the air 10 is free of material between its two radial limits 8, 9 and/or its two lateral limits 11, one of which is not illustrated in figure 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 having a cross section to the air flow F and which is rectangular curved along the arcuate profile .

The bypass passage for air 10 is commonly referred to as the air bypass 10, and may also be referred to as the "FOD" bypass, an acronym for the English expression "Foreign Object Debris". Indeed, the air bypass 10 extends longitudinally over a total extent of the exchanger 2, its main role is to allow the passage of debris contained in the air flow F through the annular vein of the turbomachinery. Debris or “FOD” can for example be birds, hail, hailstones or any other object that could obstruct or damage the exchanger.

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, and this without hindering their capacity heat exchange.

The air bypass 10 extends radially over a height h of between 10% and 20% of a cumulative radial height H of said bypass passage and of 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.

The radial height h of the air bypass 10 is constant over the total extent of the exchanger 2 according to the air flow F. Indeed, the height h does not change in any way according to the flow of [air because it is not desired to modify its speed, only the passage of debris is expected from the air bypass 10.

However, the height h may present a small variation of at most 1% of the value h, which may be related to manufacturing precision.

Advantageously, the constancy of the height h makes it possible to limit the difference in pressure drops between the air bypass 10 and the heat exchange zone 3.

However, the radial height h of the air bypass 10 may vary slightly in order to compensate for any pressure losses which may be caused by aerodynamic disturbances downstream of the exchanger 2. In this respect, the bypass d air 10 may have a convergent and/or divergent longitudinal section.

According to the first embodiment illustrated in Figure 1, the heat exchange zone 3 is radially delimited by a radially inner face 14 belonging to the radial wall 9, and a radially outer face 16 belonging to the outer wall 12.

Preferably, the exchanger 2 comprises an oil inlet and an oil outlet on the radially internal face 14.

The oil passages 4 comprise several paths between an oil inlet and an oil outlet, said paths extending radially externally to the radially internal face 14, and which are distributed along the arcuate profile of the heat exchange zone 3.

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 passing through the air by-pass.

Figure 2 illustrates a sectional view of the exchanger 2 according to a second embodiment, schematically illustrating the oil paths.

Indeed, the second embodiment consists in positioning the air bypass 10 in a radially high position so that said air bypass 10 is adjacent to the outer casing of the turbomachine. While the first embodiment consists in positioning the air bypass 10, having the same geometric configuration as what is described previously, as being adjacent to an internal casing of the turbomachine.

In this regard, and with reference to Figure 2, the exchanger 2 comprises an outer wall 12 'located radially outside the heat exchange zone 3, so as to form a radially outer guide wall of the vein of annular air.

Similar to the outer wall 12 of Figure 1, the outer wall 12 'of Figure 2 can also include a fixing flange to fix the exchanger to an external casing of the turbine engine.

In this configuration, the air bypass 10 is delimited radially by two radial limits consisting of the outer wall 12' and a radial wall 9' radially delimiting the heat exchange zone 3 on the outside. radial height h of air bypass 10 is between radial wall 9' and outer wall 12.

The exchanger 2 further comprises an inner wall 8', arranged radially internally and adjacent to the heat exchange zone 3. To this end, 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 casing of the annular air stream, said casing is preferably a casing internal to the air flow having the upstream and downstream parts fixed to the exchanger 2.

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 comprises the greatest risk of impact with the debris “ FOD” so that the air by-pass 10 is arranged there.

Figure 2 also illustrates the heat exchange zone 3 as being radially delimited by a radially inner face 14' belonging to the inner wall 8', and a radially outer face 16' belonging to the radial wall 9'.

Preferably, the exchanger 2 comprises an oil inlet 18 and an oil outlet 20 on the radially inner face 14'. However, the exchanger 2 can include the oil inlet and outlet 18, 20 on the radially outer face 16°.

The oil passages 4 comprise several paths 22 between the oil inlet 18 and the oil outlet 20 and which are distributed along the arcuate profile of the heat exchange zone 3. The exchanger 2 may include a single oil path as it may include several paths up to 10 oil paths.

Each of the paths 22 comprises at least one outward portion 26 and at least one return portion 28, the terms "outward" and "return" correspond to the main radial flow direction of the oil from the oil passages 4. In this In this regard, the forward portion 26 corresponds to a portion of the oil path 22 in which the oil flows radially from the bottom upwards. Similarly, return portion 28 corresponds to a portion of oil path 22 in which oil flows radially from top to bottom.

The two forward 26 and return 28 portions are offset along the arcuate 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. heat exchange. In addition, each of the paths 22 comprises at least one connection portion 30 connecting the at least one outward portion 26 to the at least one return portion 28.

The radially inner face 14' further comprises a distributor 32 fluidically disposed between the oil inlet 18 and the paths 22 and extending along the arcuate profile, and a manifold 34 fluidically disposed between the paths 22 and the oil outlet 20 and extending along the arcuate profile.

The oil inlet 18 is at one end of the distributor 32 following the arcuate profile and having a section of passage transverse to said arcuate profile which gradually decreases along the latter from the oil inlet 18 to an opposite end of distributor 32.

Similarly, the oil outlet 20 is at one end of the manifold 34 following the arcuate profile and having a section of passage transverse to said arcuate profile which gradually decreases along the latter from the oil outlet 20 to an opposite end of manifold 34.

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.

The present invention has two different variants concerning the oil paths. The third and fourth embodiments which will be described relate to variants of the oil path, it being understood that each of these third and fourth embodiments can apply either to the first mode or to the second mode. Indeed, one can choose a high or low radial position of the air by-pass and at the same time define the embodiment of the desired oil path.

FIG. 3 illustrates the oil paths 22 as previously described, 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 to 25 s extend over a total axial length of the heat exchange zone.

Each path 22 to 25 comprises several parallel 4 oil passages distributed over 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 oil passages 4, and more preferably, between 10 and 25 oil passages 4.

Figure 3a illustrates a perspective bottom view of the oil paths of Figure 3 which are according to the third embodiment of the invention.

To this end, the distributor 32 makes it possible to supply the oil passages 4 which are included in the go portions 26, and the connection between the distributor 32 and said go portions 26 is made by means of an inlet passage d oil 33.

Preferably, each oil inlet passage 33 is an integral part of the oil passages 4, and comprises a section of passage transverse to the air flow

F and which gradually decreases along the latter.

Advantageously, the reduction in the cross section of the oil inlet passage 33 makes it possible to reduce the pressure drops.

Similarly, the collector 34 makes it possible to recover the oil exiting from the oil passages 4 which are included in the return portions 28 by means of an oil outlet passage 35.

Figure 4 shows an oil path 22' in the exchanger according to a fourth embodiment. Preferably, the exchanger comprises a plurality of oil paths similar to oil path 22'.

The 22' oil path includes several 4' oil passages which are formed by parallel tubular channels and form a forward portion 26' and a return portion 28'. Each of the outgoing 26' and return 28' portions 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.

The exchanger according to the fourth embodiment may comprise 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 the oil inlet passages 33' and the oil outlet passages 35' which are identical. to those previously described for the third embodiment.

In the direction of oil flow, ie. from the oil inlet passage 33 to the oil outlet passage 35, the go parts 26' and the return parts 28' are interconnected via a connection portion 30'. Specifically, said connection portion 30' makes it possible to connect two third radial parts 40, each belonging to the forward part 26' and the other to the return part 28'.

Similarly and in the same direction of flow of the oil, the return parts 28' are connected to the outgoing parts 26' by means of the connection portion (not illustrated in FIG. 4. Specifically, said connection portion makes it possible to connect two first radial parts 36 each belonging to the return part 28' and the other to the outgoing part 26'.

Figure 4 illustrates a single return portion 28', however, each oil path 22' may include multiple return portions 28' and multiple forward portions 26'.

Preferably, the 22' oil path comprises two 26' outgoing parts and two 28' return parts.

The second axial parts of the forward 26′ and return 28′ portions have opposite flow directions. To this end, the second axial part 38 of the return portion 28' comprises the oil which is in a first axial flow direction opposite to the second axial part 38 of the forward portion 26', the flow direction of this latter is particularly opposed to the airflow F.

In this configuration, the heat exchange between the oil passages 4' and the air is partly carried out in counter-current. Advantageously, this allows more efficient heat exchange by convection between the 4' oil passages and the air flow.

F, this concretely makes it possible to minimize the length of the path of the oil in the 4' oil passages of the exchanger, which makes it possible to reduce the size and the weight of the exchanger in the turbomachine.

Preferably, the fourth embodiment of the invention is used in the case where the total axial extent of the heat exchange zone is greater than the total radial extent of the latter. Advantageously, this makes it possible to maximize the heat exchange in counter-current with the flow of air.

The heat exchanger of the invention has a heat exchange zone that is preferentially divergent in the radial direction and in the direction of the air flow.

Figure 5 illustrates a sectional view of the exchanger 2 according to the second embodiment, the exchanger 2 being arranged in the annular air stream.

The oil passages 4' illustrated in Figure 5 belong to the fourth embodiment of the invention. However, the divergence of the exchanger 2 is not limited to this last mode particularly, and the oil passages 4 illustrated in Figures 3 and 3a representing the third embodiment can also be used in Figure 5.

With reference to FIG. 5, the total radial height Z of the heat exchange zone 3 increases from upstream to front, and the axial air passage comprises air channels delimited by the heat exchange surfaces 6 and having passage sections increasing from upstream to downstream in correspondence with the total radial height 5 Z of the heat exchange zone 3.

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. Preferably, the sections of the air channels 5 increase from upstream to downstream over the entire total axial extent of the heat exchange zone 3.

The increase in the total radial height Z of the heat exchange zone 3 and/or the increase in the sections of the air channels 5 is monotonous and/or by at least 30%. Preferably, the increase in the sections of the air channels 5 is monotonous and by at least 50%.

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 is integrally formed in the inner wall , and at least one of the sectors comprises a short-circuiting passage (not shown) of said sector, also called an oil bypass, extending in a fluid manner between the oil inlet 18 and the outlet of oil along the inside wall.

Advantageously, the oil bypass makes it possible to ensure the cold operation of the exchanger 2, in particular at temperatures around -40° C., in fact, the cold oil has a high viscosity which is not suitable for allow it to pass through the exchanger 2, the oil therefore passes through the oil bypass until it reaches a suitable viscosity.

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

The oil bypass includes a valve normally closed and capable of opening in the presence of a pressure difference between the oil inlet 18 and the oil outlet,

greater than or equal to a limit value. The valve can also open when the viscosity of the oil is too high compared to a previously identified threshold.

Figure 6 shows an enlarged portion A of the heat exchange zone identified in Figure 2.

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.

The air channels 5 are delimited by the exchange surfaces 6 and the outward portion 26, 26' or the return portion 28, 28'. The 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 forward portion 26, 26' or a return portion 28, 28' and two exchange surfaces 6 out of the four belonging to transverse plates integrally formed with the oil passages 4, 4' of the forward portions 26, 26' or the return portions 28, 28'.

To this end, the oil passages 4, 4 can be formed by a material recess in a plate or a panel, and the outward and return portions can be included in a radial panel.

The air channels 5 between each pair of adjacent outward portions 26, 26' and return portions 28, 28 form at least two radial rows 42, 44 of nested polygons, preferably pentagonal. The number of radial rows 42, 44 may depend on the circumferential distance between the forward portion 26, 26' and the return portion 28, 28'.

The heat exchange zone further comprises edge plates 7 having the exchange surfaces 6, in fact, the edge plates 7 are similar to the plates having the exchange surfaces 6 of the heat exchange zone.

Advantageously, the edge plates 7 make it possible to guarantee heat exchange at the edges of the heat exchange zone while generating a constant pressure drop with respect to the rest of said heat exchange zone, this makes it possible to minimize the aerodynamic disturbances of the airflow in the annular vein.

The heat exchanger of the invention and according to any of the embodiments previously described, can extend continuously over 360° in a section of the annular air stream around the longitudinal axis of the turbomachine.

Preferably, the exchanger extends discontinuously over 360° around the longitudinal axis by being subdivided into several angular segments and each exchanger can ensure a heat exchange function between the air and the oil which can be different from a segment. to another.

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, outlet temperature requested or air conditions, the various circuits can be placed in thermal contact or isolated.

In this respect, the heat exchanger can ensure the cooling of the oil used in several components of the aircraft, in particular, an engine, a gearbox, an engine generator and any electronic component requiring cooling.

Advantageously, the 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 reaching 30,000 I /h.

It should be noted that the invention is not limited to the examples described in the figures. The teachings of the present invention may in particular be applicable to another type of turbomachine.

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

Claims (20)

Claims 1. Heat exchanger (2) of the air/oil type, for an annular air stream 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 presenting a profile facing the air flow (F) and included in a perpendicular plane to said air flow (F), said profile of the heat exchange zone (3) being in an arc of a circle so as to be able to be placed in the annular air stream, characterized in that said heat exchanger (2 ) comprises on a radially internal (14, 14') or external (16, 16') face 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). 2. Heat exchanger (2) according to claim 1, characterized in that each of the paths (22, 22') comprises at least one forward portion (26, 26') and at least one return portion (28, 28') , extending radially between the radially inner face (14, 14') and the radially outer face (16, 16') of the heat exchange zone (3). 3. Heat exchanger (2) according to claim 2, characterized in that each forward portion (26, 26') and each return portion (28, 28') of each of the paths (4, 4') are offset along of the arcuate profile of the heat exchange zone (3). 4. Heat exchanger (2) according to one of claims 2 and 3, characterized in that each of the paths (4, 4 ') comprises at least one connection portion (30, 30 ") connecting at least one go portion (26, 26') to [at least one return portion (28, 28') and arranged in the heat exchange zone (3). 5. Heat exchanger (2) according to one of claims 2 to 4, characterized in that 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 (3). 6. Heat exchanger (2) according to claim 5, characterized in that each path (22) comprises several parallel oil passages (4) distributed over the total axial length of the heat exchange zone (3). 7. Heat exchanger (2) according to one of claims 2 to 4, characterized in that each go portion (26 ') and each return portion (28') of each of the paths (22 ') comprises several passages of oil (4') forming a double bent flow profile with a first radial part (36), a second axial part (38) and a third radial part (40). 8. Heat exchanger (2) according to claims 4 and 7, characterized in that the at least one connection portion (30°) interconnects the first (36) or third radial parts (40) adjacent to said portion connection (30”). 9. Heat exchanger (2) according to one of claims 7 and 8, characterized in that the second axial parts (38) of the forward (26') and return (28') portions have opposite flow directions. 10. Heat exchanger (2) according to one of claims 1 to 9, comprising on the radially inner face (14, 14 ') or the radially outer face (16, 16') of the heat exchange zone (3 ) comprising the oil inlet (18) and the oil outlet (20), furthermore, a distributor (32) arranged fluidly between the oil inlet (18) and the paths (22, 22 ') and extending along the arcuate profile, and a manifold (34) fluidly disposed between the paths (22, 22') and the oil outlet (20) and extending along the arcuate profile. 11. Heat exchanger (2) according to claim 10, characterized in that the oil inlet (18) is at one end of the distributor (32) following the arcuate profile and said distributor has a passage section transverse to said arcuate profile which gradually decreases along said arcuate profile from the oil inlet (18) to an opposite end of said distributor (32). 12. Heat exchanger (2) according to one of claims 10 and 11 characterized in that the oil outlet (20) is at one end of the collector (34) following the arcuate profile and said collector (34 ) has a passage section transverse to said arcuate profile which gradually decreases along said arcuate profile from the oil outlet (20) to an opposite end of said manifold (34). 13. Heat exchanger (2) according to one of claims 10 to 12, characterized in that the distributor (32) and the collector (34) are side by side along an axial extent of the radially inner face (14 , 14') or external (16, 16') of the heat exchange zone (3) comprising the oil inlet (18) and the oil outlet (20). 14. Heat exchanger (2) according to one of claims 1 to 13, characterized in that the total radial height (Z) of the heat exchange zone (3) increases from upstream to front, and the passage of axial air comprises 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 zone of heat exchange (3). 15. Heat exchanger (2) according to claim 14, characterized in that the total radial height (Z) of the heat exchange zone (3) and/or the sections of the air channels (5) increase by upstream downstream over at least 70% of a total axial extent of said heat exchange zone (3). 16. Heat exchanger (2) according to one of Claims 14 and 15, characterized in that the increase in the total radial height (Z) of the heat exchange zone (3) and/or the increase in sections of the air channels (5) is monotonous and/or at least 30%. 17. Heat exchanger (2) according to one of claims 14 to 16, characterized in that the sections of the air channels (5) have a polygonal shape, preferably pentagonal. 18. Heat exchanger (2) according to one of claims 1 to 17, characterized in that the heat exchange zone (3) comprises the forward portions (26, 26') and the return portions (28, 28' ) extending radially and distributed along the arcuate profile, and comprising the heat exchange surfaces (6) being formed by transverse walls extending between the forward portions (26, 26') and/or the return portions (28, 28'). 19. Heat exchanger (2) according to claim 18, characterized in that the air channels (5) between each pair of go portions (26, 26 ') and return portions (28, 28') neighbors form at least two radial rows of nested polygons, preferably pentagons. 20. Heat exchanger (2) according to one of claims 18 and 19, characterized in that the transverse walls are integrally formed with the forward portions (26, 26') or with the return portions (28, 28').