METHOD FOR MANUFACTURING A HEAT EXCHANGER FOR A TURBINE ENGINE

Description

DOMAIN

[0001] The present invention relates to a method for manufacturing an annular heat exchanger for a turbomachine, in particular an annular heat exchanger intended to be mounted in a secondary air flow vein. CONTEXT

[0002] There figure 1 represents a double-flow turbomachine 10 which comprises moving parts which rub against other moving parts or against fixed parts, this connection is for example a bearing. In order not to break due to heating due to friction, the parts are sprayed with oil which allows on the one hand to limit (or contain) their heating and, on the other hand, to lubricate them to facilitate the sliding of the parts on each other.

[0003] The oil circulates in a circuit provided with heat exchangers, in particular oil / air exchangers 12, as shown in figure 2 , having a matrix, in the form of a sinuous conduit shaped so as to carry out a heat exchange, into which the oil coming from said parts is introduced then cooled before being re-injected onto said parts. The heat exchanger shown in figure 2 is an annular heat exchanger which is mounted on the radially internal or external face (relative to the longitudinal axis of the turbomachine) of an annular shell delimiting radially outwards or inwards an annular flow vein for a secondary air flow.

[0004] When starting a turbomachine in cold conditions (for example with a temperature below 0°C), the oil in the air / oil exchanger 12 (or exchangers where applicable) may be frozen, making heat exchange between the oil and the air difficult or even impossible since the oil cannot circulate in the exchanger matrix. It is then necessary to preheat the air / oil heat exchanger matrix.

[0005] To this end, it is known to provide the air / oil heat exchanger with a bypass pipe serving as a defrosting channel and which surrounds the matrix of the air / oil heat exchanger so as to heat the frozen oil. This bypass pipe is connected at its upstream end to the inlet of the heat exchanger and to the outlet of the heat exchanger. The oil circuit also comprises a valve for controlling the oil flow in the bypass pipe in order to only allow the circulation of oil in the matrix of the exchanger when the temperature is below a predetermined threshold. However, since the oil passage section of the bypass pipe is smaller than the oil passage section in the air / oil heat exchanger, there is an overpressure in the oil circuit when the matrix of the exchanger is frozen. The overpressure induces a risk of damage to the oil circuit.

[0006] In order to reduce this overpressure, it has already been proposed to connect the end of the bypass pipe to the downstream end of the bypass pipe so as to divert part of the fluid from the bypass pipe, thus reducing the fluid pressure in it under cold operating conditions. While this solution is interesting, it is however difficult to implement by machining on a heat exchanger since this requires modifying the structural integrity of the heat exchanger and requires the addition of sealing parts which are complex to implement.

[0007] US2014044525A1 describes a heat exchanger assembly for use in a gas turbine engine, the assembly comprising a bypass valve and at least one body portion. The body portion comprises at least one defrost inlet channel in flow communication with the bypass valve, a plurality of cooling channels in flow communication with the bypass valve and the at least one defrost inlet channel, and at least one defrost outlet channel in flow communication with the bypass valve and the at least one defrost inlet channel.

[0008] Document US2018087852A1 describes a double seat diverter valve for a surface heat exchanger.

[0009] The invention aims in particular to provide a simple, effective and economical solution to this problem. SUMMARY OF THE INVENTION

[0010] The present invention firstly relates to a method for manufacturing an annular heat exchanger, in particular intended to be mounted on the radially internal or external face of an annular shell of a casing of a dual-flow turbomachine, comprising the following steps: obtaining by extrusion a preform of the heat exchanger by means of a die shaped so that the preform comprises: o first pipes for the circulation of a fluid to be cooled, o second pipes arranged on either side of the first pipes in a direction perpendicular to the direction of extrusion, making a hole from the outside in the preform, this hole opening into one given of the second pipes of the preform, introducing inside said hole of the second given pipe a member for partially closing its passage section.

[0011] According to the invention, the heat exchanger is produced by extrusion, which makes it possible to obtain first and second pipes, the first pipes serving for the circulation of fluid, in particular oil, to be cooled and the second pipes serving for the circulation of fluid for defrosting the frozen fluid which is in the first pipes, which explains the arrangement on either side of the first pipes. In particular, to avoid excess pressure in the second pipe, a hole is made after obtaining the preform and it is partially closed, that is to say in such a way as to leave a small passage of fluid on either side of the closing member.

[0012] Also, the method may include: Making in a middle part of the preform and from the outside of the preform a first fluid inlet opening opening into only some of the first conduits, Making in said middle part of the preform and from the outside of the preform a first fluid outlet opening opening into said certain first conduits, Blocking the circulation of fluid in said certain first conduits in the extrusion direction between said first inlet opening and said first outlet opening.

[0013] According to the invention, the method comprises a step of producing in a middle part of the preform and from the outside of the preform a second fluid inlet opening opening into the second given pipe and a second fluid outlet opening opening into the second given pipe, said closure member being interposed along the extrusion direction between the second inlet opening and the second outlet opening.

[0014] Preferably, the method comprises the following steps: Adding fluidic connecting members to the ends of the preform so as to: create a fluid flow in the first circuit between the first inlet opening and the first outlet opening; create a fluid flow in the second circuit between the second inlet opening and the second outlet opening;

[0015] These fluid connection members can be obtained in several ways and it is not necessary here to describe a specific embodiment, the person skilled in the art understanding that machining is in particular one of the techniques which can be used to achieve the desired fluid circulation.

[0016] Also, the first inlet opening can be made by forming a recess in the thickness of the preform followed by making holes for fluid connection to said certain first pipes.

[0017] Furthermore, the second inlet opening may be produced by forming said recess followed by producing a fluid connection hole to said second given pipe. Thus, in this configuration, the recess formed in the preform forms the first inlet opening and the second inlet opening.

[0018] The method may also include a step of adding a sealing plate to the middle portion of the preform, this plate being provided with a fluid passage cutout. The edges of the cutouts are provided with closed-contour seals applied to the preform so as to create a sealed joint.

[0019] Also, the sealing plate may be covered with a plate provided with fluid connection conduits for supplying fluid to the first and second conduits and for emitting fluid from the first and second conduits.

[0020] The invention will be better understood and other details, characteristics and advantages of the invention will appear on reading the following description given by way of non-limiting example with reference to the appended drawings. BRIEF DESCRIPTION OF THE FIGURES

[0021] there figure 1 is a schematic perspective view of a turbomachine according to the known technique; figure 2 is a schematic perspective view of part of an annular heat exchanger mounted in the turbomachine of the figure 1 ; there figure 3 is a schematic view of an exchanger intended to be produced with the method according to the invention and which shows more particularly the flow of oil; figure 4 is a schematic perspective view illustrating the various constituent parts of the heat exchanger obtained with the method according to the invention; figure 5 is a schematic perspective view illustrating the installation of a partial blocking pin for a pipe in the second circuit; figure 6 is a schematic sectional view of the assembly of the parts of the figure 4 . DETAILED DESCRIPTION

[0022] There figure 3 schematically represents the principle of circulation of a fluid to be cooled, in particular oil, in a heat exchanger 12 as represented in figure 2 . As shown, the exchanger comprises a first circuit formed by first pipes 11 and 18 for the circulation of oil to be cooled and a second circuit formed by second pipes 23 and 24 for the circulation of defrosting oil from the first pipes 11 and 18. The exchanger 12 is an annular exchanger which extends around the axis of the turbomachine. On the figure 3 the longitudinal dimension of the exchanger in the L direction and the circumferential dimension of the exchanger in the C direction are represented.

[0023] As can be seen, some of the first pipes 11 extend between two fluid connection members 14, 16, while other first pipes 18 comprise a first portion 18a and a second portion 18b. The first portions 18a of the first pipes 18 are connected at their upstream ends to a common oil supply inlet 20 and at their downstream ends to the first fluid connection member 14. The first pipes 11 are connected upstream to the first fluid connection member 14 and downstream to the second fluid connection member 16. The outlet of the second fluid connection member 16 is connected to the second portions 18b of the first pipes 18, the downstream ends of which are connected to an oil outlet 22.

[0024] The second conduits 23, 24, in this case two in number, are formed on either side of the first conduits 11, 18 in the longitudinal direction L. One of the second conduits 23 extends between the first 14 and second 16 fluid connection members. The other 24 of the second conduits comprises a first portion 24a connected to an oil inlet which is here the same oil inlet 20 as that supplying the first portions 18a of the first conduits 18. The downstream end of the first portion 24a of the second conduit 24 is connected to the first fluid connection member 14 which supplies the second conduit 23 at the inlet, which second conduit 23 in turn supplies oil to the second fluid connection member 16 communicating at the outlet with the second portion 24b of the second conduit 24.At the outlet, this second portion 24b of the second pipe 24 is connected to an opening / closing valve 26, which authorizes or prohibits the flow of oil in the second pipes 23, 24. Thus, this valve 26 authorizes or not the circulation of oil in the channel surrounding the first pipes 11, 18 in order to heat them in the event of freezing of the latter in cold operating conditions. This defrosting channel is formed by the first portion 24a of the second pipe 24, the first fluid connection member 14, the second pipe 23, the second fluid connection member 16, the second portion 24b of the second pipe 24.

[0025] Are also visible on the figure 3 , a separator 28 provided for fluidly separating the first portions 18a and second portions 18b of the first pipes 18 and a pin 30 for partially closing the second pipe 24, the interest of these parts appearing fully below.

[0026] To avoid excess pressure in the defrosting pipe, an oil bypass is provided between the inlet 20 and the outlet 22 of the defrosting pipe. Thus, a portion of the oil can flow directly from the upstream end of the first portion 24a of the second pipe 24 to the downstream end of the second portion 24b of the second pipe 24 without passing through the second pipe 23 since the pin 30 partially blocks the fluid passage section and delimits a channel 31 for bypassing the defrosting channel.

[0027] We now refer to the figures 4 And 5 . To produce the heat exchanger 12 thus described previously, the method according to the invention proposes firstly to provide a block ready to be inserted into a die and to produce a preform by extrusion, which preform 32 is shaped so as to comprise: first pipes 11, 18 for the circulation of a fluid to be cooled (only a first pipe 11 and a first pipe 18 are illustrated in dotted lines on the figure 4 ), second conduits 23, 24 arranged on either side of the first conduits 11, 18 in a direction perpendicular to the extrusion direction.

[0028] The first conduits 11, 18 and the second conduits 23, 24 are parallel to each other. The first conduits 11, 18 thus extend from one end to the other of the preform 32 obtained immediately after extrusion. The same is true of the second conduits 23, 24 which surround the first conduits 11, 18. In the application of the heat exchanger 12 indicated here, there is only one second conduit 23, 24 on either side of the first conduits 11, 18, even if there could be more.

[0029] In a subsequent step, a hole 34 is made from the outside of the preform 32, this hole 34 opening into the second given pipe 24. More precisely, this hole 34 separates the first portion 24a of the second pipe 24 and the second portion 24b of the second pipe 24 as previously explained. To make the aforementioned bypass without it hindering the nominal operation of the defrosting pipe, a member 30, here a pin, is introduced into the hole 34 to partially close the passage section of the second pipe 24.

[0030] At this stage of preform preparation, the preform has first and second conduits that open at the circumferential ends of the preform. However, there is still no oil inlet or outlet.

[0031] Thus, an opening 36 is made in a middle portion in a direction perpendicular to the preform 32. This opening 36 comprises a recess 38 in the bottom 40 of which holes 42 are made opening into the first portions 18a of the first pipes 18. Another hole 44 is also made in the bottom 40 of the recess 38 and communicates with the upstream end of the first portion 24a of the second pipe 24. Thus, the recess 38 and the holes 42 form a first oil inlet opening 36a of the first circuit. Also, the recess 38 and the hole 44 form a second oil inlet opening 36b of the second circuit.

[0032] To allow oil to exit, a first oil exit opening 46 is also made, which includes a recess 48 formed in the thickness of the preform 32 and in the bottom 50 of which holes 52 are made for oil to exit the second portions 18b of the first pipes 18.

[0033] To prevent oil from circulating between the first 18a and second 18b portions of the first pipes 18, a separator 28 is inserted between the first oil inlet opening 36a and the first oil outlet opening 46, in the direction perpendicular to the extrusion.

[0034] Also, a second oil outlet opening 54 is provided and allows oil to exit from the downstream end of the second portion 24b of the second pipe 24.

[0035] Thus produced, the preform allows, when combined with the first 14 and second 16 fluid connection members, to form the heat exchanger 12 delimiting the first oil circuit for cooling the oil and the second oil circuit for defrosting the first oil circuit.

[0036] As is well represented on the figure 4 , a sealing plate 56 is interposed between the middle part of the preform 32 and a collection plate 58. The sealing plate 56 comprises three cutouts, a first cutout 56a is intended to surround the periphery of the recess 38, a second cutout 56b is intended to surround the periphery of the recess 48 and a third cutout 56c is intended to surround the outlet of the second outlet opening 54. Seals 58 are mounted on the peripheries of the first, second and third cutouts 56a, 56b, 56c and provide sealing on the preform 32. The collection plate 58 comprises an oil supply conduit 58a from the recess 38 for supplying oil to the first circuit and the second circuit and an oil outlet conduit 58b from the recess 48. It also comprises an oil outlet conduit 58c from the second oil outlet opening 54.

[0037] There figure 6 illustrates a sectional view of the parts shown in figures 4 And 5 In this figure, it can be seen that the pin 30 for partial closure of the second given pipe 24 is blocked in translation by the collection plate 58 and by a flat 60 resting on the preform 32.

Claims

1. Method for manufacturing an annular heat exchanger (12), in particular intended to be mounted on the radially inner or outer face of an annular shell of a casing of a double-flow turbomachine, comprising the following steps: - obtaining by extrusion a heat exchanger (12) preform (32) by means of a die shaped so that the preform (32) comprises: o first pipes (11, 18) for the circulation of a fluid to be cooled, o second pipes (23, 24) arranged on either side of the first pipes (11, 18) in a direction perpendicular to the direction of extrusion, - making a hole (34) from the outside in the preform (32), this hole (34) leading into one (24) of the second pipes of the preform (32), - introducing into said hole (34) of the second given pipe (24) a member (30) for partially closing off its passage cross-section said method being characterized in that it comprises a step of making in a middle portion of the preform (32) and from the outside of the preform (32) a second fluid inlet aperture (36b) opening into the second given pipe (24) and a second fluid outlet aperture (54) opening into the second given pipe (24), said sealing member (30) being interposed along the extrusion direction between the second inlet aperture (36b) and the second outlet aperture (54).

2. Method according to claim 1, comprising: - Making in said middle part of the preform (32) and from the outside of the preform (32) a first fluid outlet aperture (36a) opening into said certain first pipes (18), - Making in said middle part of the preform (32) and from the outside of the preform a first fluid outlet aperture (46) opening into said certain first pipes (18), - Blocking the flow of fluid in said certain first pipes (18) in the direction of extrusion between said first inlet aperture (36a) and said first outlet aperture (46).

3. Method according to claim 2, comprising: - Adding fluidic bonding members (14, 16) to the ends of the preform (32) so as to: o create a fluid flow in the first circuit between the first inlet aperture (36a) and the first outlet aperture (46); o create a fluid flow in the second circuit between the second inlet aperture (36b) and the second outlet aperture (54).

4. Method according to claim 3, wherein the first inlet aperture (36a) is made by forming a recess (38) in the thickness of the preform (32) followed by making holes (42) for fluidic connection to said certain first pipes (18).

5. Method according to claim 4, wherein the second inlet aperture (36b) is made by forming said recess (38) followed by making a hole (44) for fluidic connection to said second given pipe (24).

6. Method according to one of claims 1 to 5, comprising a step of adding a sealing plate (56) to the middle part of the preform, this plate being provided with fluid passage cut-outs.

7. Method according to claim 6, wherein the sealing plate (56) can be covered with a collecting plate (58) provided with fluid connection pipes for the fluid supply to and the fluid outlet from the first and second pipes.