Surface heat exchanger comprising a pressure loss reducer and aircraft nacelle provided with such a heat exchanger

Abstract

The invention relates to a heat exchanger (20), in particular for an aircraft nacelle, comprising a first skin (21) and a second skin (22) joined together, and a plurality of channels (23) for distributing a hydraulic fluid (F1) arranged between the first skin (21) and the second skin (22), wherein the exchanger further comprises a first hydraulic interface (24) and a second hydraulic interface (29) for the hydraulic fluid. The exchanger (20) further comprises at least one pressure loss reduction member (40) extending axially towards the first hydraulic interface (24) or the second hydraulic interface (25), wherein the pressure loss reduction member (40) has a generally conical cross-section.

Description

[0001] DESCRIPTION

[0002] TITLE: Surface heat exchanger comprising a pressure drop reducer and aircraft nacelle equipped with such a heat exchanger

[0003] Technical field of the invention

[0004] The present invention relates to the field of heat exchangers, in particular fairings of an aircraft engine, called "nacelle".

[0005] State of the prior art

[0006] Climate change is a major concern for many legislative and regulatory bodies around the world. Indeed, various restrictions on carbon emissions have been, are being, or will be adopted by various states. In particular, an ambitious standard applies to both new aircraft types and those already in operation, requiring the implementation of technological solutions to comply with current regulations. Civil aviation has been mobilizing for several years now to make a contribution to the fight against climate change.

[0007] Technological research efforts have already made it possible to significantly improve the environmental performance of aircraft. The Applicant takes into consideration the impact factors in all phases of design and development to obtain less energy-intensive, more environmentally friendly aeronautical components and products whose integration and use in civil aviation have moderate environmental consequences with the aim of improving the energy efficiency of aircraft.

[0008] Consequently, the Applicant is constantly working to reduce its negative climate impact by using methods and operating virtuous development and manufacturing processes and minimizing greenhouse gas emissions to the minimum possible in order to reduce the environmental footprint of its activity.

[0009] This sustained research and development work focuses on new generations of aircraft engines, the weight reduction of aircraft, particularly through the materials used and lighter on-board equipment, the development of the use of electrical technologies to ensure propulsion, and, as an essential complement to technological progress, aeronautical biofuels.

[0010] Generally, an aircraft is powered by one or more propulsion units, each comprising an engine or turbojet housed in a tubular nacelle.

[0011] A nacelle generally comprises a tubular body comprising an upstream section comprising an air inlet upstream of the turbojet engine, a middle section configured to surround a fan of the turbojet engine and a downstream section configured to house thrust reverser means and to surround the combustion chamber of the turbojet engine. The nacelle generally comprises an exhaust nozzle downstream of the downstream section and the outlet of which is located downstream of the turbojet engine.

[0012] In addition, the nacelle usually includes an external structure and an internal fixed structure, called "inner fixed structure", acronym "IFS" in English terms. The internal fixed structure is concentric with the external structure, at the downstream section and surrounds the core of the turbojet downstream of the fan.

[0013] These external and internal structures define an annular flow vein, called a secondary vein, aimed at channeling a flow of cold air, called secondary, circulating outside the turbojet.

[0014] The external structure comprises an external fairing defining an external aerodynamic surface and an internal fairing defining an internal aerodynamic surface. The internal and external fairings are connected upstream by a leading edge wall forming an air inlet lip.

[0015] Generally, the turbojet engine comprises a set of blades driven in rotation by a gas generator through a set of transmission means. The nacelle further comprises a lubricant distribution system to ensure good lubrication of these transmission means and to cool them. The lubricant is advantageously oil. In order to cool the lubricant, the nacelle generally comprises a cooling system comprising at least one heat exchanger. The cooling system is configured to circulate a fluid, for example the lubricant or a coolant which will cool the lubricant.

[0016] There are air / lubricant heat exchangers that use air taken from the secondary stream (called cold flow) of the nacelle or one of the first stages of the compressor. The taking and circulation of air through the heat exchanger disrupts the flow of the air stream and causes additional pressure losses, called drag, which is not desirable.

[0017] Finned heat exchangers are also known, fixed to one of the walls of the nacelle delimiting the secondary vein. The fluid is cooled by the flow of air in the secondary vein along the fins on the surface of the exchanger.

[0018] Such a solution also generates significant aerodynamic losses, which leads to significant losses in fuel consumption.

[0019] Fluid cooling systems are also known comprising a structural surface exchanger, i.e. an exchanger without fins and forming a generally smooth contact surface with the fluid circulating outside the exchanger, so as to avoid pressure losses caused by the presence of fins.

[0020] In the example illustrated in FIG. 1, a structural surface exchanger 10 without fins comprises a first corrugated skin 11 and a second so-called smooth skin 12, assembled to form distribution channels 13 which allow the flow of a fluid F, for example, a heat transfer fluid or a lubricant, from an inlet interface 14 to a fluid outlet interface 15.

[0021] The inlet 14 and outlet 15 hydraulic interfaces are calibrated to best distribute an identical flow rate in each distribution channel 13.

[0022] However, these hydraulic interfaces induce significant pressure losses that need to be reduced. Current exchangers present risks of non-uniform distribution of flow rates between the different distribution channels, which degrades their thermal efficiency.

[0023] Indeed, as visible in figure 1, when the fluid arrives perpendicular to the smooth skin 12 or aerodynamic skin before supplying the distribution channels 13, the fluid F makes a change of direction of 90°, generating significant pressure losses.

[0024] In order to maximize the thermo-hydraulic performance of the surface exchanger, the pressure losses must be as low as possible and the flow distribution almost identical from one channel to another.

[0025] These pressure losses must also be minimized in order to limit the dimensions, weight and cost of the on-board circulation pumps which are required to overcome these pressure losses.

[0026] Concerning surface exchangers with rectangular section channels, it is known to reduce the dispersion of flows by increasing or reducing the width of these channels so as to equalize the pressure losses.

[0027] However, in the case of surface exchangers with semi-circular section channels, the design of the channels does not allow the section of said channels to be easily modified.

[0028] There is a need to improve fluid cooling systems, especially surface heat exchangers.

[0029] Statement of the invention

[0030] The present invention therefore aims to overcome the aforementioned drawbacks.

[0031] The objective of the invention is to reduce the pressure losses inherent in the inlet and / or outlet interfaces of a heat exchanger, to promote a homogeneous distribution of the flow of the fluid in the distribution channels and thus to improve the thermal exchanges between respectively a fluid circulating inside and the air circulating outside said heat exchanger.

[0032] The subject of the invention is a heat exchanger, preferably surface heat exchanger, in particular for an aircraft nacelle, comprising a first skin or wall and a second skin or wall assembled together and a plurality of distribution channels for a hydraulic fluid arranged between the first skin and the second skin. The exchanger further comprises a first hydraulic interface, for example an inlet hydraulic interface, and a second hydraulic interface, for example an outlet hydraulic interface.

[0033] Said exchanger further comprises at least one pressure loss reduction member extending axially towards the first hydraulic interface or the second hydraulic interface, said pressure loss reduction member having a generally conical section.

[0034] The pressure drop reduction device is an intermediate part which separates the hydraulic flow entering the inlet hydraulic interface and distributes it in each distribution channel of the exchanger.

[0035] In the outlet hydraulic interface, the pressure loss reduction device allows the different hydraulic flows arriving from the distribution channels to be collected in a homogeneous manner.

[0036] The particular conical shape of the pressure drop reducer makes it possible to reduce pressure drops without reducing the passage of the hydraulic flow in the associated hydraulic interface.

[0037] Thanks to the invention, the plane change transition between the associated hydraulic interface and the second smooth skin of the surface exchanger is softened thanks to the pressure loss reduction member extending towards the associated hydraulic interface.

[0038] Furthermore, the thermal exchanges between a fluid circulating in the heat exchanger and the air circulating outside said heat exchanger are optimized, while improving the structural strength of the heat exchanger and reducing aerodynamic pressure losses.

[0039] Advantageously, the pressure drop reduction member extends axially at least partly in the first hydraulic interface or the second hydraulic interface. This makes it possible to improve the fluidity of the transition and therefore a better reduction in pressure drops.

[0040] Preferably, at least one of the first and second hydraulic interfaces respectively forms an angle with the second skin, preferably greater than or equal to 60°, for example equal to 90°.

[0041] Preferably, each of the distribution channels is connected directly to the inlet hydraulic interface and the outlet hydraulic interface.

[0042] The distribution channels extend in a single plane. In other words, no part of the distribution channels protrudes beyond either skin. This allows for a substantially flat exchanger.

[0043] For example, each of the distribution channels is connected directly to the first hydraulic interface and to the second hydraulic interface and the distribution channels are regularly distributed around the entire perimeter of the associated hydraulic interface.

[0044] This allows for a larger number of channels and for a uniform distribution at the input or output regardless of the number of channels. This also limits load losses by directly supplying each channel from the input interface.

[0045] By "surface exchanger" we mean an exchanger without fins, a smooth exchanger, whose wall or skin which defines the vein forms the heat exchange surface.

[0046] The fact of not having fins, or other shapes intended to increase the contact surface between the flow and the exchanger, allows there to be no obstacle to the air flow in the vein, and therefore to reduce aerodynamic load losses.

[0047] The first skin and the second skin can be, for example, sheets of metal.

[0048] The term "sheet metal" means a flat steel product, rolled either hot or cold, with a generally smooth surface or sometimes with projections. A sheet metal is therefore made of metallic material.

[0049] The distribution channels are configured to extend in a single plane between the first hydraulic interface and the second hydraulic interface.

[0050] By "distributed around the entire perimeter of the hydraulic interface" is meant that certain channels are connected to one of the hydraulic interfaces by a first end extending in a direction opposite to the other of the hydraulic interfaces.

[0051] The ends are extended by a main part, for example rectilinear, extending towards the other of the hydraulic interfaces to a second end.

[0052] The second end may also extend in a direction opposite one of the hydraulic interfaces.

[0053] For example, the channels are connected to the inlet hydraulic interface by an inlet end and to the outlet hydraulic interface by an outlet end.

[0054] The input end is, for example, connected to the output end by a main part.

[0055] An inlet end of at least one channel extends in a direction opposite the outlet hydraulic interface and an outlet end of at least one channel extends in a direction opposite the inlet hydraulic interface.

[0056] For example, the inlet and outlet hydraulic interfaces have a circular cross-section.

[0057] For example, the inlet and outlet hydraulic interfaces each comprise an outlet orifice extending in a plane perpendicular to the extension planes of the skins.

[0058] Advantageously, the thickness of each distribution channel is constant over the entire length of the corresponding channel.

[0059] For example, distribution channels have an identical cross-section between them.

[0060] Alternatively, different cross-sections could be provided between each of the channels. For example, the longer distribution channels could be provided with a larger cross-section in order to balance the flow rates between the said distribution channels.

[0061] Advantageously, the pressure loss reduction device is a solid of revolution.

[0062] By "solid of revolution" we mean that each specific zone of the pressure loss reduction device introducing the hydraulic flow into each distribution channel is repeated as many times as there are distribution channels.

[0063] Preferably, the pressure drop reduction member comprises a base directed towards the second skin on the side opposite the associated hydraulic interface and a conical-shaped hydraulic flow deflection portion extending from the base towards a top and directed towards the associated hydraulic interface, on the side opposite the second skin.

[0064] In no way limiting, the summit is located at the center of the associated hydraulic interface.

[0065] The hydraulic flow diversion portion extends, for example, at least partly into the associated hydraulic interface.

[0066] Advantageously, the base of the pressure loss reduction member has a shape homothetic or similar to the associated hydraulic interface, for example circular, oval, etc.

[0067] In all cases, it is important not to restrict the passage section of the hydraulic flow between the cylindrical inlet of the associated interface and the passage at the right of the hydraulic flow diversion part.

[0068] The circular shape of the base of the pressure loss reduction device allows for stress-free fixing in the associated hydraulic interface.

[0069] According to one embodiment, the hydraulic flow deflection portion of the pressure drop reduction member comprises a smooth external surface.

[0070] According to another embodiment, the hydraulic flow deflection portion of the pressure drop reduction member comprises an external surface comprising a plurality of concave facets, with curved faces or not, said concave facets extending from the base to the top and are connected to said top.

[0071] Each concave facet is preferably located opposite an associated distribution channel.

[0072] Thus, the concave facets help guide the flow in each distribution channel or help each incident hydraulic flow to exit with the smallest pressure loss.

[0073] According to another embodiment, the hydraulic flow deflection portion of the pressure drop reduction member comprises an external surface comprising a plurality of protrusions regularly distributed around the periphery of the cone and a plurality of grooves or recesses regularly distributed around the periphery of the cone in an alternating manner with the protrusions, each protrusion extending from the base to the top and being connected to said top. Each groove preferably forms a flow path located opposite an associated distribution channel.

[0074] Said grooves allow to guide the flow in each distribution channel or help each incident hydraulic flow to exit with the smallest pressure loss.

[0075] By "growth" we mean an extruded elongated surface.

[0076] The growths have, for example, a curved face.

[0077] Alternatively, one could provide that the growths have a non-curved face.

[0078] Alternatively, it could also be provided that the pressure loss reduction member is a generally conical solid of revolution formed by triangular vertical plates to separate the incident flow or direct the incoming flow.

[0079] According to one embodiment, the pressure loss reduction member is integrated directly into the second skin or the associated hydraulic interface.

[0080] By "directly integrated" is meant that the pressure drop reduction device is integral with the second skin or the associated intermediate hydraulic interface without an intermediate element, by any non-removable fixing means such as welding, gluing, brazing, riveting or any removable fixing means such as screwing, or even made in one piece with the second skin or the associated intermediate hydraulic interface.

[0081] According to one embodiment, the exchanger comprises a plate fixed to the second skin and provided with studs arranged between the second and first skins, so as to ensure the fixing of said interfaces to the first and second skins by means of fixing means cooperating with said studs. The pressure loss reduction member is preferably integrated directly into the plate.

[0082] By "directly integrated" we mean that the pressure drop reduction device is integral with the plate without any intermediate element, by any non-removable fixing means such as welding, gluing, brazing, riveting or any removable fixing means such as screwing, or even made in one piece with the plate.

[0083] The force paths can thus be optimized in order to reduce the total mass and the mechanical stress margins according to the different cases of mechanical stresses, such as hydraulic loads and aerodynamic and mechanical loads.

[0084] According to one embodiment, each of the first and second skins is flat.

[0085] Alternatively, each of the first and second skins is curved to ensure aerodynamic continuity with the rest of the nacelle.

[0086] Advantageously, the exchanger comprises a plurality of spacers or spacing members arranged between the first skin and the second skin, two adjacent spacing members delimiting a distribution channel.

[0087] For example, the first skin and the second skin are assembled together by an assembly zone, for example welding or brazing, at the level of the spacing members, said assembly zone extending from the first skin to the second skin.

[0088] According to one embodiment, the first skin comprises a plurality of corrugations, the distribution channels each being delimited by a corrugation of the first corrugated skin and the second skin.

[0089] For example, each distribution channel has a semicircular section.

[0090] Generally, the first skin has a thickness between 0.6mm and 3mm and the second skin has a thickness between 0.6mm and 4mm.

[0091] The first skin and / or the second skin is made of aluminum or an alloy containing aluminum. This improves the lightness, the formability of the skins and thermal exchanges.

[0092] According to a second aspect, the invention relates to a turbomachine nacelle comprising an external structure and an internal structure delimiting an annular secondary flow vein, said nacelle comprising a housing for a turbomachine, which delimits with the internal structure an annular primary flow vein. The nacelle comprises at least one heat exchanger as described above fixed either in the external structure, on the side of the secondary vein or on the side external to said external structure, or in the internal structure or internal fairing, on the side of the secondary vein.

[0093] When the exchanger is fixed in the internal fairing, the second skin of the heat exchanger is in contact with the air flow circulating in the secondary vein.

[0094] When the exchanger is fixed in the internal structure of the nacelle, the second skin of the heat exchanger is in contact with the air flow circulating in the secondary vein.

[0095] Alternatively, it could be provided that when the exchanger is fixed in the external structure of the nacelle, the second skin of the heat exchanger can be in contact with the external air flow.

[0096] Thus, the heat exchanger can be used to cool a fluid from the secondary flow or from the outside air.

[0097] Brief description of the drawings

[0098] Other aims, characteristics and advantages of the invention will appear on reading the following description, given solely by way of non-limiting example, and made with reference to the indexed drawings in which:

[0099] [Fig 1], is a schematic view of a sectional view of a structural surface exchanger according to the prior art;

[0100] [Fig 2] is a schematic view of a surface heat exchanger according to one embodiment of the invention;

[0101] [Fig 3] is a detailed view in partial section of the exchanger according to the invention along section III-III of figure 2;

[0102] [Fig 4] is a detailed view in partial section of the exchanger according to the invention along section IV-IV of figure 2;

[0103] [Fig 5] is a perspective view of a pressure drop reducer of the exchanger of Figure 4;

[0104] [Fig 6] is a perspective view of a pressure drop reducer according to a second embodiment of the invention; [Fig 7] is a perspective view of a pressure drop reducer according to a third embodiment of the invention;

[0105] [Fig 8] is a partial sectional view of a surface heat exchanger according to another embodiment of the invention;

[0106] [Fig 9A], [Fig 9B] are views of a surface heat exchanger according to another embodiment of the invention;

[0107] [Fig 10] is a partial sectional view of a surface heat exchanger according to another embodiment of the invention; and

[0108] [Fig H] is a schematic view of a nacelle equipped with a heat exchanger according to one of the embodiments of the invention.

[0109] Detailed description of at least one embodiment

[0110] In the remainder of the description, the terms "upstream" and "downstream" are defined in relation to the direction of air flow in the turbomachine. The terms "internal" and "external" are defined in relation to the longitudinal axis of the turbomachine, the internal term defining an element closer to said axis than an external element.

[0111] With reference to the example illustrated in Figures 2 to 4, a heat exchanger 20 comprises a first skin 21, for example a sheet metal, and a second skin 22, for example a sheet metal.

[0112] The first skin 21 comprises a plurality of undulations 21a, for example, produced by forming said first skin 21 and the second skin 22 is here flat.

[0113] The exchanger 20 comprises a plurality of distribution channels 23 each delimited by a corrugation 21a of the first corrugated skin 21 and the second skin 22 called smooth.

[0114] Each distribution channel 23 has a semicircular section. Alternatively, it could be provided that the section has any general shape.

[0115] As illustrated, the distribution channels 23 have a section of identical size between them.

[0116] Alternatively, different sized sections could be provided between each of the channels. For example, the longer distribution channels could be provided with a larger section in order to balance the flow rates between the distribution channels.

[0117] The distribution channels 23 are connected, here, directly respectively to a first hydraulic interface 24, for example an inlet hydraulic interface, and a second hydraulic interface 25, for example an outlet hydraulic interface.

[0118] In this description, the inlet and the outlet are defined relative to the normal flow direction of the cooling fluid in the exchanger.

[0119] As illustrated in Figure 2, the inlet ends 23a of the distribution channels 23 are distributed uniformly, that is to say regularly, over the entire circumference of the inlet hydraulic interface 24 and the outlet ends 23b of the distribution channels 23 are distributed uniformly over the entire circumference of the outlet hydraulic interface 25.

[0120] By "distributed over the entire circumference" is meant that an inlet end 23a of at least one channel 23 extends in a direction opposite to the outlet hydraulic interface 25 and that an outlet end 23b of at least one channel 23 extends in a direction opposite to the inlet hydraulic interface 24.

[0121] The inlet ends 23a of the channels 23 and the outlet ends 23b of the channels 23 have a curved shape.

[0122] The inlet ends 23a and the outlet ends 23b of the channels 23 are connected to each other by a main part 23c, here rectilinear.

[0123] In the embodiment illustrated in Figure 2, the exchanger 20 comprises a first anteroposterior axis of symmetry S1-S1 passing through the inlet interface 24 and the outlet interface 25 and a transverse axis of symmetry S2-S2 perpendicular to the axis S1-S1. The distribution channels 23 are arranged symmetrically with respect to the axis of symmetry S1-S1.

[0124] The concavity of the inlet ends 23a and the outlet ends 23b of the channels 23 is directed towards the center of the exchanger 20 constituted by the intersection of the two axes of symmetry S l -S l and S2-S2. Alternatively, it remains possible for the exchanger not to have an axis of symmetry.

[0125] The distribution channels 23 are arranged in the same plane, not projecting beyond the skins 21, 22. Thus, the channels do not create additional bulk in the overall thickness of the exchanger.

[0126] By "thickness" is meant the dimension in the direction along the ZZ axis perpendicular to the longitudinal axis of extension of the exchanger and to the transverse axis of the exchanger.

[0127] The longitudinal axis is parallel to the Sl-Sl axis and the transverse axis is parallel to the S2-S2 axis.

[0128] In the example illustrated in Figure 2, and in a non-limiting manner, the hydraulic interfaces 24, 25 are aligned along the first axis of symmetry Sl-Sl.

[0129] Alternatively, it could be provided that the hydraulic interfaces 24, 25 are aligned along another axis, for example a transverse axis.

[0130] In general, the invention is not limited to the shape of the distribution channels, which are configured to extend in the longitudinal direction between the inlet hydraulic interface 24 and the outlet hydraulic interface 25.

[0131] The first and second skins 21, 22 are assembled by a welding or brazing zone 26, 27, visible in FIG. 3, on either side of the corrugation 21a of the first corrugated skin 21. Said welding or brazing zone 26, 27 extends from the first corrugated skin 21 to the second skin 22.

[0132] The exchanger 20 is a heat exchanger between a first hydraulic fluid E1 and air E2. The hydraulic fluid E1 is intended to circulate in the channels 23 and the air is intended to circulate in contact with the second smooth skin 22.

[0133] Generally, the first skin 21 has a thickness of between 0.6 mm and 3 mm and the second skin 22 has a thickness of between 0.6 mm and 4 mm.

[0134] The first skin 21 and / or the second skin 22 is made of aluminum or an alloy comprising aluminum. This makes it possible to improve the lightness, thermal exchanges and formability of the skins.

[0135] Exchanger 20 is, for example, watertight up to 1000 meters.

[0136] As illustrated in Figure 2, and by way of non-limiting example, the exchanger 20 comprises eight distribution channels 23.

[0137] Alternatively, the heat exchanger 20 could comprise a different number of distribution channels 23, for example greater than or equal to three, or greater than or equal to four.

[0138] As illustrated in Figure 4, the hydraulic interface, here the hydraulic input interface 24 is orthogonal to the second skin 22 called smooth.

[0139] Generally speaking, the invention finds a particularly advantageous application for at least one of the hydraulic interfaces respectively forming an angle with the second skin 22 called smooth, preferably greater than 60°, for example equal to 90°.

[0140] In the example illustrated, each hydraulic interface 24, 25 respectively forms an angle equal to 90° with the second skin 22 called smooth of the exchanger.

[0141] Figure 4 is a partial sectional view of the connection of an input 24 or output 25 interface to the first skin 21 and to the second skin 22, according to the invention.

[0142] As illustrated in Figure 4, the input interface 24, and similarly the output interface 25, have an extension axis Y coincident here with the vertical axis ZZ.

[0143] However, it could be provided that the input interface 24 and / or the output interface 25 are understood along an extension axis Y forming a non-zero angle with the vertical axis ZZ, or even secant to the vertical axis Z- Z-.

[0144] With reference to the example illustrated in Figures 4 and 5, the heat exchanger 20 comprises a plate 30 fixed to the second skin 22, preferably by welding with beads 30a.

[0145] The plate 30 comprises a plurality of studs 31 projecting axially along an axis ZZ perpendicular to the extension plane of the exchanger 20.

[0146] The pads 31 are arranged between the second skin 22 and the first skin 21 and between the corrugations 21a of the first skin 21. The pads 31 here have a cylindrical cross-section.

[0147] The connection between the plate 30, the first skin 21 and the corresponding hydraulic interface 24, 25 is made with screws 32 each comprising a head 33 and a threaded rod 34.

[0148] The threaded rods 34 pass through a base 24a of the corresponding hydraulic interface 24, 25 and the first skin 21 and cooperate with corresponding threads (not referenced) provided on the studs 31, so as to tighten the base 24a, 25a and the first skin 21 between the heads of the screws 32 and the studs 31.

[0149] The flow of the hydraulic fluid F is schematically represented by the arrows connecting a hydraulic interface 24 and distribution channels 23. The direction of flow naturally depends on the type of interface. Thus, the direction of flow is from an inlet interface 24 to distribution channels 23 and from distribution channels 23 to an outlet interface 25.

[0150] As illustrated in Figure 4, the heat exchanger 20 further comprises a pressure drop reduction member 40 extending axially here partly in the inlet hydraulic interface

[0151] 24.

[0152] It could be provided that the heat exchanger 20 further comprises a second pressure loss reduction member 40 extending axially partly in the outlet hydraulic interface.

[0153] 25.

[0154] Generally, the heat exchanger 20 comprises at least one pressure loss reduction member 40 extending axially towards the associated hydraulic interface 24, 25.

[0155] The pressure drop reduction member 40 is an intermediate part which separates the hydraulic flow entering the inlet hydraulic interface 24 and distributes it in each distribution channel 23 of the exchanger 20. In the outlet hydraulic interface 25, the pressure drop reduction member 40 makes it possible to collect the different hydraulic flows arriving from the distribution channels 23 in a homogeneous manner.

[0156] As illustrated, the pressure loss reduction member 40 is of revolution, that is to say that each specific zone introducing the hydraulic flow into each distribution channel 23 is repeated as many times as there are channels 23.

[0157] The pressure loss reduction member 40 has a shape adapted to the number of channels 23 to be supplied.

[0158] The pressure loss reduction member 40 comprises a base 41, here circular, directed towards the second skin 22 on the side opposite the associated hydraulic interface 24, 25, and a conical-shaped hydraulic flow deflection portion 42 extending from the base 41 towards an apex S and directed towards the associated hydraulic interface 24, 25, on the side opposite the second skin 22.

[0159] As illustrated and in no way limiting, the vertex S is located at the center of the associated hydraulic interface 24, 25.

[0160] The hydraulic flow diversion portion 42 here extends at least partly into the associated hydraulic interface 24, 25.

[0161] Generally, the base 41 of the pressure loss reduction member 40 has a shape homothetic or similar to the associated hydraulic interface and may be circular, oval, etc.

[0162] The circular shape of the base 41 of the pressure loss reduction member 40 allows for stress-free fixing in the associated hydraulic interface 24, 25.

[0163] In geometry, a "solid of revolution" is generated by a closed plane surface rotating around an axis located in the same plane as it and having no points in common with it or only points on its boundary.

[0164] A cone is a ruled surface defined by a straight line, called the generator, passing through a fixed point S called the vertex and a variable point describing a curve, called the directrix curve. In the cone of revolution, the directrix curve is a circle with center O, visible in Figure 4, located in a plane perpendicular to SO . This cone is called a cone of revolution because it can be generated simply by rotating the generator around a vertical axis of rotation SZ passing through the vertex S .

[0165] The particular conical shape of the pressure drop reducer 40 makes it possible to reduce pressure drops without reducing the passage of the flow of the hydraulic flow F at the inlet or outlet.

[0166] In the embodiment illustrated in Figures 4 and 5, the pressure loss reduction member 40 is integrated directly into the plate 30.

[0167] By "directly integrated" is meant that the pressure drop reduction member 40 is integral with the plate 30 without any intermediate element, by any non-removable fixing means such as welding, gluing, brazing, riveting or any removable fixing means such as screwing, or even made in one piece with the plate 30.

[0168] The force paths can thus be optimized in order to reduce the total mass and the mechanical stress margins according to the different cases of mechanical stresses, such as hydraulic loads and aerodynamic and mechanical loads.

[0169] In this embodiment, the outer surface 42a of the conically shaped hydraulic flow deflecting portion 42 is smooth.

[0170] In the embodiment illustrated in Figure 6, in which the same elements bear the same references, the external surface 42a of the conical-shaped hydraulic flow deflection portion 42 comprises a plurality of concave facets 42b, here with a curved face.

[0171] Alternatively, it could be provided that the external surface 42a of the conical-shaped hydraulic flow deflection portion 42 comprises a plurality of concave facets 42b with a non-curved face.

[0172] The concave facets 42b extend from the base 41 to the vertex S and are connected to said vertex S.

[0173] The concave facets 42b are intended to be located opposite an associated distribution channel 23 and make it possible to guide the flow in each distribution channel 23 or help each incident hydraulic flow to exit with the smallest pressure loss.

[0174] In the embodiment illustrated in Figure 7, in which the same elements bear the same references, the external surface 42a of the conical-shaped hydraulic flow deflection part 42 comprises a plurality of protrusions 42c regularly distributed around the periphery of the cone and a plurality of grooves 42d or recesses regularly distributed around the periphery of the cone in an alternating manner with the protrusions 42c.

[0175] By "growth" we mean an extruded elongated surface.

[0176] Each outgrowth 42c extends from the base 41 to the vertex S and are connected to said vertex S.

[0177] The 42c growths here have a curved face.

[0178] Alternatively, it could be provided that the growths 42c have a non-curved face.

[0179] The grooves 42d form flow paths intended to be located opposite an associated distribution channel 23 and make it possible to guide the flow in each distribution channel 23 or help each incident hydraulic flow to exit with the smallest pressure loss.

[0180] Alternatively, it could also be provided that the pressure loss reduction member 40 is a generally conical solid of revolution formed by triangular vertical plates to separate the incident flow or direct the incoming flow.

[0181] In the embodiment illustrated in Figure 8, in which the same elements bear the same references, the pressure loss reduction member 40 is integrated directly into the second smooth skin 22.

[0182] By "directly integrated" is meant that the pressure drop reduction member 40 is integral with the second skin 22 without an intermediate element, by any non-removable fixing means such as welding, gluing, brazing, riveting or any removable fixing means such as screwing, or even made in one piece with the second skin 22.

[0183] In the example illustrated in FIG. 8, the pressure loss reduction member 40 has a conical shape with a smooth external surface 42a.

[0184] Alternatively, any form of the pressure drop reduction member 40 could be provided as described with reference to FIGS. 6 and 7.

[0185] In the embodiment illustrated in Figures 9A, 9B and 10, in which the same elements bear the same references, the pressure loss reduction member 40 is integrated directly into the associated hydraulic interface 24, 25.

[0186] By "directly integrated" is meant that the pressure drop reduction member 40 is integral with the associated hydraulic interface 24, 25 without an intermediate element, by any non-removable fixing means such as welding, gluing, brazing, riveting or any removable fixing means such as screwing, in the example of figure 10 or even made of the same material as the associated hydraulic interface 24, 25, in the example visible in figures 9A and 9B.

[0187] In the example illustrated in Figures 9A and 9B, the pressure loss reduction member 40 comprising a conical-shaped hydraulic flow deflection portion 42 having a generally conical-shaped external surface 42a comprises a plurality of protrusions 42c regularly distributed around the periphery of the cone and a plurality of grooves 42d or recesses regularly distributed around the periphery of the cone in an alternating manner with the protrusions 42c.

[0188] Each outgrowth 42c extends, here, from the base 41 to the summit S and are connected to said summit S.

[0189] The 42c growths here have a curved face.

[0190] Alternatively, it could be provided that the growths 42c have a non-curved face.

[0191] Alternatively, any form of the pressure drop reduction member 40 could be provided as described with reference to FIGS. 5 and 6.

[0192] The heat exchangers 20 described above are advantageously intended to equip a nacelle 60 of a turbomachine 50 or aircraft engine visible in FIG. 11.

[0193] In Figure 11 is shown very schematically an axial section of a turbomachine 50, of general longitudinal axis X-X', for example of the double-flow and double-spool turbojet type comprising a fan 51, coupled to a gas turbine engine comprising a low-pressure compressor 52, a high-pressure compressor 53, an annular combustion chamber 54, a high-pressure turbine 55 and a low-pressure turbine 56.

[0194] The rotors of the high-pressure compressor and the high-pressure turbine are connected by a high-pressure (HP) shaft (not shown) and form with it a high-pressure body. The rotors of the low-pressure compressor and the low-pressure turbine are connected by a low-pressure (LP) shaft (not shown) and form with it a low-pressure body. The HP and LP shafts extend along a longitudinal axis X-X' of the turbomachine 50.

[0195] The fan shaft is rotatably connected to the LP shaft directly or indirectly.

[0196] It will be noted that the invention is not limited to such a turbomachine structure and could be applied to a turbomachine of different structure, for example to a turbomachine of the double-flow turbojet type, in which the low-pressure compressor acts as a fan. The nacelle 60 of the turbomachine comprises a housing 61 for the turbomachine 50 and has a tubular structure comprising an external fairing 62 defining an external aerodynamic surface and an internal fairing 63 defining an internal aerodynamic flow surface through the turbomachine 50 and in particular the fan 51.

[0197] The outer and inner fairings 62, 63 are connected upstream by an air inlet lip wall 64 forming a leading edge of the nacelle 60.

[0198] The external and internal fairings 62, 63 delimit an external structure usually comprising a fixed part and a mobile part (not shown), such as for example thrust reversal means.

[0199] The nacelle 60 further comprises a fixed internal structure 65, called “inner fixed structure”, with the acronym “IFS” in English terms. The fixed internal structure 65 is concentric with the external structure, at a downstream section and surrounds the core of the turbojet engine 50 downstream of the fan 51.

[0200] These external and internal structures define an annular flow vein, called secondary vein VS, aimed at channeling a flow of cold air, called secondary, circulating outside the turbomachine 50.

[0201] Downstream of the blower 51, the main air flow FPP is separated by the fixed internal structure 65 of the nacelle, here acting as a separation member, into a primary air flow FP and a secondary air flow FS.

[0202] The primary air flow FP travels through an internal passage or primary vein VP when entering the low pressure compressor 52, for example at the level of inlet guide vanes 57 or “inlet guide vanes”, acronym IGV in English terms.

[0203] The secondary air flow FS passes through an external annular passage or secondary vein VS, for example towards outlet guide vanes 58 or "outlet guide vanes", acronym OGV in Anglo-Saxon terms, then towards the outlet of the turbomachine.

[0204] The nacelle 60 is equipped with a heat exchanger 20, fixed here in the internal structure 63 of said nacelle 60. Thus, the second skin 22 of the heat exchanger 20 configured to carry out the heat exchange is in contact with the air flow circulating in the secondary vein VS.

[0205] Alternatively, it could be provided that the heat exchanger 20 is fixed in the internal structure 65 of the nacelle 60.

[0206] According to another variant, the heat exchanger 20 can be fixed in the external fairing 62 of the nacelle 60 with the second skin 22 of the heat exchanger 20 in contact with the outside air.

[0207] According to yet another variant, the heat exchanger 20 could be fixed in the internal structure 65, with the second skin 22 of the heat exchanger 20 in contact with the air flow circulating in the secondary vein VS.

[0208] The cooling air circulates through the exchanger, in particular the second skin 22 called smooth where it recovers part of the thermal energy from the heat transfer fluid.

[0209] Thanks to the invention, the plane change transition between the hydraulic interface and the second smooth skin 22 of the surface exchanger 20 is softened thanks to the pressure loss reduction member 40 extending into the associated hydraulic interface 24, 25.

[0210] Furthermore, the heat exchanges between a fluid circulating in the heat exchanger 20 and the air circulating outside said heat exchanger are optimized, while improving the structural strength of the heat exchanger and reducing aerodynamic pressure losses.

Claims

CLAIMS 1. Heat exchanger (20) in particular for an aircraft nacelle, comprising a first skin (21) and a second skin (22) assembled together and a plurality of distribution channels (23) for a fluid (F l ) arranged between the first skin (21) and the second skin (22), the exchanger further comprising a first hydraulic interface (24) and a second hydraulic interface (25) for said fluid, characterized in that said exchanger (20) further comprises at least one pressure drop reduction member (40) extending axially towards the first hydraulic interface (24) or the second hydraulic interface (25), said pressure drop reduction member (40) having a generally conical section and in that the pressure drop reduction member (40) comprises a base (41) directed towards the second skin (22) on the side opposite the associated hydraulic interface (24,25) and a conical-shaped hydraulic flow deflection portion (42) extending from the base (41) towards a top (S) and directed towards the associated hydraulic interface (24, 25), on the side opposite the second skin (22)., 2. Exchanger (20) according to claim 1, in which the pressure loss reduction member (40) extends axially at least partly in the first hydraulic interface (24) or the second hydraulic interface (25).

3. Exchanger (20) according to claim 1 or 2, in which at least one of the first and second interfaces (24, 25) forms an angle with the second skin (22), preferably greater than or equal to 60°.

4. Exchanger (20) according to any one of the preceding claims, in which the base (41) of the pressure loss reduction member (40) has a shape homothetic to the associated hydraulic interface (24, 25).

5. Exchanger (20) according to any one of the preceding claims, in which the portion (42) for diverting the hydraulic flow of the pressure loss reduction member (40) comprises a smooth external surface (42a).

6. Exchanger (20) according to any one of the preceding claims, in which the hydraulic flow deflection portion (42) of the pressure loss reduction member (40) comprises an external surface (42a) comprising a plurality of concave facets (42b), said concave facets (42b) extending from the base (41) to the apex (S) and are connected to said apex (S) and in which each concave facet (42b) is located opposite a associated distribution channel (23).

7. Exchanger (20) according to any one of the preceding claims, in which the pressure loss reduction member (40) is integrated directly into the second skin (22) or into the associated hydraulic interface (24, 25).

8. Exchanger (20) according to any one of claims 1 to 6, comprising a plate (30) fixed to the second skin (22) and provided with studs (31) arranged between the second and first skins (21, 22), so as to ensure the fixing of said hydraulic interfaces (24, 25) to the first (21) and second (22) skins by means of fixing means (32) cooperating with said studs (31) and in which the pressure loss reduction member (40) is integrated directly into the plate (30).

9. Turbomachine nacelle (60) comprising an external structure (62, 63) and an internal structure (65) delimiting an annular secondary flow vein (VS), said nacelle (60) comprising a housing for a turbomachine (50), which delimits with the internal structure (65) an annular primary flow vein (VP), the nacelle (60) comprising at least one heat exchanger (20) according to any one of the preceding claims fixed either in the external structure (62, 63), on the side of the secondary flow vein (VS) or on the side external to said external structure (62, 63), or in the internal structure (65), on the side of the secondary flow vein (VS).

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