Improved surface heat exchanger for aircraft nacelles

Abstract

The invention relates to a surface heat exchanger, in particular for an aircraft nacelle, comprising a first metal sheet (2) and a second metal sheet (3) assembled together and a plurality of distribution channels (4) for a fluid arranged between the first metal sheet (2) and the second metal sheet (3), the exchanger further comprises an inlet interface (5) and an outlet interface (6) for the fluid. The exchanger further comprises distribution means defining, for each distribution channel (4), a flow cross-section of a fluid through which each of the distribution channels (4) is connected to the inlet interface (5) and the outlet interface (6), the distribution channels (4) being distributed over the entire periphery of the inlet interface (5) and / or the outlet interface (6).

Description

TECHNICAL FIELD

[0001] The present invention relates to the field of heat exchangers, in particular to the field of heat exchangers for nacelles, called "short cowlings", of aircraft engines. BACKGROUND

[0002] Climate change is a major issue of concern for many legislative and regulatory authorities worldwide. Indeed, countries have, are or will be taking various measures to limit carbon emissions. In particular, an ambitious standard applies both to new aircraft and to aircraft in service, requiring the implementation of technical solutions to make these aircraft compliant with the current regulations. For many years, civil aviation has been committed to contributing to the fight against climate change.

[0003] Various technical research works have made it possible to significantly improve the environmental performance of aircraft. The Applicant has considered the influencing factors at all design and development stages to obtain aircraft components and products that consume less energy and are more environmentally friendly, and to introduce and use these aircraft components and products in civil aviation with a moderate environmental impact to improve the energy efficiency of aircraft.

[0004] Thus, the Applicant is constantly striving to reduce its negative climate impact by using appropriate methods and taking advantage of appropriate development and manufacturing processes, and to reduce its activities' environmental footprint as much as possible by reducing greenhouse gas emissions.

[0005] This continuous research and development work covers the development of new generations of aircraft engines, the lightening of aircraft, in particular by the materials used and lighter on-board equipment, the development of the use of electrical technology to provide propulsion, and, as an integral part of technological progress, aviation biofuels.

[0006] Generally, an aircraft is propelled by one or more propulsion units, each comprising an engine or turbojet housed in a tubular nacelle.

[0007] Generally, a turbojet comprises a set of blades that is rotated by a set of transmission means by a gas generator. The nacelle also comprises a lubricant distribution system to ensure good lubrication and cooling of these transmission means. Advantageously, the lubricant is oil.

[0008] 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 that will cool the lubricant.

[0009] There are air / lubricant heat exchangers that use air taken from a by-pass duct of the compressor, but this causes an additional pressure drop.

[0010] There also exist finned heat exchangers attached to one of the walls of the nacelle to cool the fluid by circulating the air in the secondary duct along the fins, but this solution also generates significant aerodynamic losses.

[0011] These aerodynamic losses result in an increase in fuel consumption.

[0012] Fluid cooling systems comprising structural surface exchangers, i.e. exchangers without fins and forming a smooth integral contact surface with the fluid circulating outside the exchanger, are also known, thus avoiding the pressure drop due to the presence of fins.

[0013] Such structural surface exchangers generally comprise a first corrugated metal sheet and a second smooth metal sheet assembled to form distribution channels allowing the cooling fluid to flow from a distributor to a fluid manifold.

[0014] Such heat exchangers also comprise one or more stiffeners arranged between the first and second metal sheets and configured to provide structural strength to the exchanger.

[0015] However, the presence of the distributor and manifold increases the difficulty of forming the exchanger, due to the risk of tearing the metal sheets.

[0016] In addition to the manufacturing difficulty mentioned, the current exchangers present the risk of uneven distribution of flow between the different distribution channels, which degrades the thermal efficiency of these exchangers.

[0017] Furthermore, the stiffeners are an anomaly that disturbs the flow and causes significant pressure drops. SUMMARY

[0018] The present invention thus aims to reduce the pressure drop inherent in the inlet / outlet interfaces of a heat exchanger, thus improving the heat exchange between the fluid circulating inside the heat exchanger and the air circulating outside the heat exchanger, while optimizing the structural strength of the heat exchanger.

[0019] The object of the present invention is a heat exchanger, in particular for an aircraft nacelle, comprising a first metal sheet and a second metal sheet assembled together and a plurality of channels for distributing a fluid arranged between the first and second metal sheets, the heat exchanger also comprising an inlet interface and an outlet interface for the fluid.

[0020] The exchanger also comprises distribution means for distributing the fluid, the distribution means defining, for each distribution channel, a flow section of the fluid, each of the distribution channels being connected to the inlet interface and to the outlet interface by such a flow section, the distribution channels being distributed over the entire periphery of the inlet interface and / or of the outlet interface.

[0021] Such an exchanger improves the fluid flow between the interfaces and the distribution channels and makes it possible to control the flow distribution between the distribution channels.

[0022] Advantageously, the flow section defined for each distribution channel has a value that depends on the length of the channel, in order to make the flow rates of the distribution channels uniform with one another.

[0023] Such a definition of the flow section makes it possible to control the flow distribution between the distribution channels.

[0024] For example, the plurality of channels comprises a first channel and a second channel having different cross sections.

[0025] Advantageously, the heat exchanger comprises a plate fastened to the second metal sheet and provided with studs arranged between the second metal sheet and the first metal sheet, in order to fix the interfaces to the first metal sheet and to the second metal sheet by means of fastening means cooperating with the studs.

[0026] Such fastening means are, for example, screws, bolts, bars or rivets.

[0027] Preferably, the studs comprise threaded holes and the distribution means comprise a metal sheet provided with holes aligned with the threaded holes of the studs.

[0028] For example, the distribution means comprise vertical walls arranged between the studs and the distribution channels, the walls having a constant thickness and being oriented radially with respect to the longitudinal axis of the inlet interface and / or of the outlet interface.

[0029] Such walls make it possible to improve the flow around the studs, thereby reducing the pressure drop inside the heat exchanger.

[0030] For example, the distribution means comprise vertical walls of varying thickness arranged between the studs and the inlet and outlet ends of the distribution channels, in order to reduce the turbulence generated by the flow of the fluid.

[0031] Advantageously, the distribution means comprise a leading edge and a trailing edge formed by circular arcs, the convexity of the arcs pointing towards the center of the plate.

[0032] According to another feature, the plate is provided with throttling elements, which are designed to be placed in the inlet and / or outlet ends of these distribution channels in order to reduce the useful cross-section of these channels at the location of these throttling elements.

[0033] According to another aspect, the present invention relates to a turbine engine nacelle comprising at least one heat exchanger as described above. Attached Figure Description

[0034] Other objects, features, and advantages of the invention will become apparent upon reading the following description, which is by way of non-limiting example only, and with reference to the accompanying drawings, in which: [ Figure 1 [This is a schematic diagram of a surface heat exchanger according to an embodiment of the present invention;] [ Figure 2 ]for Figure 1 A detailed view of a partial screenshot of the switch; [ Figure 3 ]and[ Figure 4 [1] A partial sectional view and a plan view of the connection between the inlet interface or the outlet interface of the exchanger according to an embodiment of the present invention; [ Figure 5 A plan view of the connection point of the inlet or outlet interface of a switch according to a second embodiment of the present invention is shown. [ Figure 6 The diagram shows a plan view of the connection between the inlet or outlet interface of a switch according to a third embodiment of the present invention. [ Figure 7 A plan view of the connection point of the inlet or outlet interface of a switch according to a fourth embodiment of the present invention is shown. [ Figure 8 [I] is a perspective view of the board of a switch according to the fifth embodiment of the present invention; [ Figure 9 ]yes[ Figure 8 A partial sectional view of the throttling component of the plate; [ Figure 10 [ ] is a plan view of the distribution device, illustrating the principle that the flow cross-section Sp of the channel varies with the length of the channel; and [ Figure 11 [Illustration] is a schematic diagram of a nacelle equipped with a heat exchanger according to one embodiment of these embodiments of the invention. Detailed Implementation

[0035] refer to Figure 1 and Figure 2 The example shown includes a first surface layer or first metal sheet 2 and a second surface layer or second metal sheet 3.

[0036] The first metal sheet 2 comprises a plurality of corrugations 4c and the second metal sheet 3 is flat in the present case.

[0037] The exchanger 1 comprises a plurality of distribution channels 4, each distribution channel being delimited by a corrugation 5 of the first metal sheet 2 which is corrugated and by a so-called smooth second metal sheet 3.

[0038] The exchanger 1 is a heat exchanger between a first fluid Fl and air F2. The fluid Fl is intended to circulate in the channels 4 and the air F2 is intended to circulate in contact with the smooth second metal sheet 3.

[0039] Each distribution channel 4 has a semi-circular cross-section. Alternatively, it can be provided that this cross-section has any general shape.

[0040] As illustrated, the distribution channels 4 have cross-sections of identical dimensions to one another.

[0041] Alternatively, it is possible to provide sections with different dimensions between each of these channels.

[0042] The distribution channels 4 are connected respectively to an inlet interface 5 and to an outlet interface 6.

[0043] In other words, there is neither a collector nor a distributor between the channels 4 and the inlet interface 5, and between the channels 4 and the outlet interface 6.

[0044] In the present description, the inlet and the outlet are defined with respect to the normal direction of flow of the cooling fluid in the exchanger.

[0045] As Figure 1 illustrated, the inlet ends 4a of these distribution channels 4 are uniformly distributed, i.e. evenly distributed, over the entire periphery of the inlet interface 5 and the outlet ends 4b of these distribution channels 4 are uniformly distributed over the entire periphery of the outlet interface 6.

[0046] The inlet ends 4a of the channels 4 and the outlet ends 4b of the channels 4 have a curved shape.

[0047] The inlet ends 4a and the outlet ends 4b are connected together by straight portions 4d.

[0048] In the embodiment illustrated in Figure 1 , the exchanger 1 comprises a front-rear symmetry axis S1-S1 passing through the inlet interface 5 and the outlet interface 6 and a transverse symmetry axis S2-S2 perpendicular to the axis S1-S1. The distribution channels 4 are arranged symmetrically with respect to said symmetry axis S1-S1. The concave faces of the inlet ends 4a and of the outlet ends 4b of the channels 4 are directed towards the centre of the exchanger 1 formed by the intersection of these two symmetry axes S1-S1 and S2-S2.

[0049] In a variant, the exchanger can still not have a symmetry axis.

[0050] The first metal sheet 2 and the second metal sheet 3 are assembled by means of a welding or brazing zone 8, 9 on both sides of the corrugations 4c of the corrugated metal sheet 2. This welding or brazing zone 8, 9 extends from the first metal sheet 2 to the second metal sheet 3 (Fig. 1). Figure 2

[0051] Figure 3 is a partial view of the connection of the inlet interface 5 or outlet interface 6 according to the application with the first metal sheet 2 and the second metal sheet 3.

[0052] With reference to the example shown in Figure 3 and Figure 4 , the heat exchanger 1 comprises a plate 10 fastened to the second metal sheet 3, preferably by welding with a bead 10a.

[0053] The plate 10 is provided with a stud 11 arranged between the second metal sheet 3 and the first metal sheet 2 and between each corrugation 4c of the first metal sheet 2. The stud 11 has here a cylindrical cross section.

[0054] The connection is made with a screw 12 comprising a head 13 and a threaded rod 14.

[0055] The threaded rod 14 passes through a base 15 of the interface 5, 6 and the first metal sheet 2 and works with a corresponding thread provided on the stud 11 in order to clamp the base 15 and the first metal sheet 2 between the head of the screw 12 and the stud 11.

[0056] The exchanger 1 comprises eight distribution channels 4 distributed over the entire circumference of the inlet interface 5 or outlet interface 6 (Fig. 1). Figure 4 In a variant, the heat exchanger 1 can comprise a different number of distribution channels 4, for example greater than or equal to three.

[0057] The heat exchanger 1 also comprises distribution means 16 for distributing the fluid F1.

[0058] The flow of the fluid F1 is schematically represented by the arrows connecting the interface 5, 6 and the distribution channels 4. Naturally, the flow direction depends on the type of interface. Thus, the flow direction is from the inlet interface 5 to the distribution channels 4 and from the distribution channels 4 to the outlet interface 6.

[0059] The distribution means 16 define, for each distribution channel 4, a flow section Sp of the fluid F1, each channel 4 being connected to the inlet interface 5 and to the outlet interface 6 by such a flow section Sp. Preferably, the area of the flow section Sp can be adjusted for each distribution channel 4. This makes it possible to control the distribution of the fluid flow between the different distribution channels.​

[0060] The flow section Sp of the distribution channel 4 is the useful section that allows the fluid F1 to flow to or from the channel.

[0061] Preferably, the flow section Sp is parallel to the inlet or outlet cross section S of the corresponding distribution channel 4, so as to reduce the pressure drop. Preferably, the flow section Sp is centered with respect to the inlet or outlet cross section S of the corresponding distribution channel 4, so as to reduce the pressure drop. For example, the flow section Sp is considered centered with respect to the cross section S of the corresponding channel 4 when a ray passing through the respective centers of sections Sp and S at an equal distance from two adjacent distribution devices 16 also passes through the center C of the given distribution channel 4.

[0062] For example, in order to make the flow rate uniform between the distribution channels 4, the flow section Sp corresponding to a given distribution channel depends on the length of the channel. The length of the distribution channel 4 is understood to be the distance measured on the curvilinear axis of the distribution channel between the center C corresponding to the inlet interface 5 and the center C corresponding to the outlet interface 6. For example, the flow section Sp is proportional to the length of the channel, in particular when the distribution channels have the same cross section as each other. Thus, in the case where the channel C1 and the channel C2 have the same cross section, an enlarged flow section Spe is associated with the channel C1 having a greater length, and a reduced flow section Spr is associated with the channel C2 having a smaller length. Figure 10 .

[0063] The distribution device 16 comprises a sheet of metal 16a provided with a hole aligned with the threaded hole of the stud 11 of the plate 10. This alignment facilitates the positioning of the distribution device 16 with respect to the plate 10 and allows the passage of the stem 14 of the screw 12 through the sheet of metal 16a to improve the fixing.

[0064] In the embodiment shown in Figure 3 and Figure 4 , the distribution device 16 comprises a vertical wall 17 provided between the stud 11 and the distribution channel 4. The wall 17 has a constant thickness e and is oriented radially with respect to the longitudinal axis X of the interfaces 5, 6, which intersects the plate 10 perpendicularly at the center C.

[0065] Another embodiment is shown in Figure 5 , in which the same elements bear the same reference numerals.

[0066] Figure 5 The embodiment shown in Figure 3 and Figure 4The difference of the illustrated embodiment consists only in that the distribution device 16 comprises a vertical wall 18 of variable thickness. The wall 18 is arranged between the pegs 11 and the inlet end 4a and the outlet end 4b of the distribution channels 4 so as to reduce the turbulence generated by the flow of the fluid F1.

[0067] Figure 6 Another embodiment is illustrated, which differs from the one illustrated in that Figure 5 The difference of the illustrated embodiment consists only in that the cross section of each peg 11 comprises two opposite circular arcs 11a, 11b connected by two straight segments, the circular arcs 11a, 11b having different radii from each other. In a variant, the two circular arcs 11a, 11b can still be replaced by other curved shapes, in particular ellipses or parabolas.

[0068] The pegs 11 can be identical to each other, but alternatively, they can also be different.

[0069] Figure 7 Another embodiment is illustrated, in which the distribution device 16 surrounds the pegs 11 so that the fluid F1 does not come into contact with the pegs 11.

[0070] The distribution device 16 comprises a front edge and a rear edge formed by a circular arc 19, the convexity of which is directed towards the center C of the plate 10.

[0071] In a variant, the circular arc 19 can still be replaced by other curved shapes, in particular ellipses or parabolas.

[0072] The metal sheet 16a is not illustrated in Figure 5 to Figure 7 so as not to make these figures redundant and to facilitate understanding.

[0073] Figure 8 is a perspective view of the plate 10 and of the distribution device 16, the distribution device 16 comprising a vertical wall 17 of constant thickness. In Figure 8 The example illustrated, the plate 10 comprises a throttling member 21 intended to be placed in the inlet end 4a and / or in the outlet end 4b so as to reduce the flow section of the fluid. The dimensions of the member 21 can vary from one channel 4 to another. In Figure 8 The example illustrated, the plate 10 is provided with a throttling member 21 the dimensions of which vary between a minimum dimension 22 corresponding to the longest channel and a maximum dimension 23 corresponding to the shortest channel. The variable relative dimensions of the throttling member 21 make it possible to adjust the distribution of the fluid flow rate between the different distribution channels 4.

[0074] Figure 9 is a sectional view of a throttling member 21 provided in a distribution channel 4. The presence of the throttling member 21 reduces the useful section Su of the channel 4. It should be noted that as the cross section of the throttling member increases, the useful section Su decreases accordingly. In Figure 9In the example shown, the throttling member 21 has a cross-section in the form of a truncated half-circle. In a variant, it remains possible for the cross-section of the throttling member 21 to have a different shape, in particular a half-circle or a polygon.

[0075] Advantageously, the heat exchanger 1 described above is intended to be equipped in the nacelle of a turbine engine or aircraft engine, visible in Figure 11 Fig. 1.

[0076] Figure 11 An axial section of a turbine engine 50 is shown highly diagrammatically, of the type having a general longitudinal axis X-X', for example of the double-rotor bypass turbojet type, comprising a fan 51 and 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.

[0077] The rotor of the high-pressure compressor and the rotor of the high-pressure turbine are connected and form a high-pressure spool by means of a high-pressure (HP) shaft (not shown). The rotor of the low-pressure compressor and the rotor of the low-pressure turbine are connected and form a low-pressure spool by means of a low-pressure (LP) shaft (not shown). The HP shaft and the LP shaft extend along the longitudinal axis X-X' of the turbine engine 50.

[0078] The fan shaft is connected rotationally, directly or indirectly, to the LP shaft.

[0079] It should be noted that the application is not limited to this turbine engine structure, but can be applied to turbine engines having different structures, for example of the bypass turbojet type, in which the low-pressure compressor serves as a fan.

[0080] The nacelle 40 of the turbine engine comprises a housing 41 for the turbine engine 50 and has a tubular structure comprising an outer fairing 42 defining an outer aerodynamic surface and an inner fairing 43 defining an inner aerodynamic surface for passing the flow through the turbine engine 50, in particular the fan 51.

[0081] The outer fairing 42 and the inner fairing 43 are connected upstream by an air intake lip 44 forming a leading edge of the nacelle 40.

[0082] The outer fairing 42 and the inner fairing 43 delimit an outer structure generally comprising a fixed part and a movable part (not shown), for example a thrust reverser.

[0083] The nacelle 40 also comprises an inner fixed structure 45, referred to in English as "inner fixed structure" and abbreviated "IFS". The inner fixed structure 45 is concentric with the outer structure at the downstream section and surrounds the core of the turbojet engine 50 downstream of the fan 51.

[0084] These outer and inner structures define an annular flow duct, referred to as secondary duct VS, intended to channel a cold flow of air, referred to as secondary flow, which circulates outside the turbojet engine 50.

[0085] Downstream of the fan 51, the primary flow F is separated into a primary flow FP and a secondary flow FS by the inner fixed structure 45 of the nacelle, which acts here as a separation member.

[0086] The primary flow FP passes through the inner channel or primary duct VP while entering the low-pressure compressor 52, for example at the inlet guide vanes (IGV) 57 of the low-pressure compressor 52.

[0087] The secondary flow FS passes through the outer annular channel or secondary duct VS, for example in the direction of the outlet guide vanes (OGV) 58, then to the outlet of the turbojet engine.

[0088] The nacelle 40 is equipped with a heat exchanger 1, which is here fixed to the inner surface of the inner fairing 43. The heat exchanger 1 is fixed in the secondary duct VS so that the flow circulating in the secondary duct VS is in contact with the second metal sheet 3 of the heat exchanger 1.

[0089] Alternatively, it can be provided to fix the heat exchanger 1 to the outer surface of the inner structure 45 of the nacelle 40.

[0090] According to another variant, the heat exchanger 1 can be fixed to the outer surface of the outer fairing 42 of the nacelle 40. Thus, the heat exchanger 1 can be used to cool the fluid coming from the secondary flow FS or from the outside air.

[0091] According to yet another variant, the heat exchanger 1 can be fixed to the inner surface of the inner structure 45, i.e. in the fluid flow of the primary duct VP.

[0092] Thus, the heat exchanger 1 can be used to heat the fluid coming from the primary flow FP.

Claims

1. Heat exchanger (1), in particular for an aircraft nacelle, comprising a first metal sheet (2) and a second metal sheet (3) assembled together and a plurality of channels (4) for distributing a fluid (Fl) provided between the first metal sheet (2) and the second metal sheet (3), the heat exchanger further comprising an inlet interface (5) and an outlet interface (6) for the fluid, characterized in that, The exchanger also comprises dispensing means (16) for dispensing the fluid (Fl), which define, for each dispensing channel (4), a flow section (Sp) of the fluid (Fl), each of the plurality of dispensing channels (4) being connected to the inlet interface (5) and to the outlet interface (6) through this flow section (Sp), the plurality of dispensing channels (4) being distributed on the entire periphery of the inlet interface (5) and / or of the outlet interface (6).

2. The heat exchanger (1) according to claim 1, wherein The flow section (Sp) defined for each dispensing channel (4) has a value that depends on the length of the channel (4) in order to make the flow rate of the dispensing channels (4) uniform with each other.

3. The heat exchanger (1) according to claim 1 or 2, wherein The plurality of channels (4) comprises first channels and second channels having different cross sections (S).

4. Heat exchanger (1) according to any one of the preceding claims, comprising a plate (10) fastened to the second metal sheet (3) and provided with studs (11) arranged between the second metal sheet and the first metal sheet in order to fix the interfaces (5, 6) to the first metal sheet (2) and to the second metal sheet (3) by means of fastening means (12) cooperating with the studs (11).

5. The heat exchanger (1) according to claim 4, wherein The studs (11) comprise threaded holes and the dispensing means (16) comprise a metal sheet (16a) provided with holes aligned with the threaded holes of the studs (11).

6. The heat exchanger (1) according to claim 4 or 5, wherein The means (16) for dispensing the fluid comprise vertical walls (17) arranged between the studs and the dispensing channels, the walls having a constant thickness and being oriented radially with respect to the longitudinal axis (X) of the inlet interface (5) and / or of the outlet interface (6).

7. The heat exchanger (1) according to claim 4 or 5, wherein The dispensing means (16) comprise vertical walls (18) of varying thickness arranged between the studs (11) and the inlet ends (4a) and outlet ends (4b) of the dispensing channels (4) in order to reduce the turbulence generated by the flow of the fluid (Fl).

8. The heat exchanger (1) according to claim 7, wherein The dispensing means (16) for dispensing the fluid (Fl) comprise a leading edge and a trailing edge formed by a circular arc (19), the convexity of the arc (19) pointing towards the centre (C) of the plate (10).

9. The heat exchanger (1) according to any one of claims 4 to 8, wherein The plate (10) is provided with throttling members (21) intended to be placed in the inlet ends (4a) and / or outlet ends (4b) of the dispensing channels (4) in order to create a reduction in the useful section of the channels (4) at the location of the throttling members (21).

10. A nacelle (40) of a turbojet engine comprising at least one heat exchanger (1) according to any one of the preceding claims.

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