Aircraft turbine engine comprising an improved heat exchanger

Abstract

The invention relates to an aircraft turbine engine comprising a primary airflow duct in which there are arranged a low-pressure compressor and a high-pressure compressor, at least one lubrication chamber (38) for lubricating at least one component (50) of the turbine engine, and a pressurized-air circuit bleeding a stream of air from the primary duct at the high-pressure compressor, and feeding it to said chamber, wherein the pressurized-air circuit comprises a heat exchanger (44) for cooling the airflow bled from the primary duct. According to the invention, the heat exchanger (44) is formed in at least one wall (58) of the lubrication chamber (38).

Description

[0001] DESCRIPTION

[0002] Title of the invention: Aircraft turbomachine comprising an improved heat exchanger

[0003] TECHNICAL FIELD

[0004] The invention relates to a turbomachine, such as an aircraft turbomachine comprising means for cooling a component preferably located near a main axis of the turbomachine.

[0005] The invention relates more particularly to a turbomachine comprising means for pressurizing lubricating oil chambers.

[0006] PREVIOUS STATE OF THE ART

[0007] Modern turbomachinery has numerous internal engine air circuits. These circuits perform various functions.

[0008] Among these circuits, one performs the function of pressurizing the lubricating oil reservoirs to prevent oil from escaping them. Optionally, this circuit also provides cooling for the high-pressure compressor discs and / or the low-pressure shaft.

[0009] The air for this circuit is, for example, taken from the intermediate crankcase, upstream of the high-pressure compressor.

[0010] Document FR3078368 describes a turbomachine for which pressurization air is taken from the high-pressure compressor.

[0011] As this document indicates, the temperature of this air is relatively high, so a heat exchanger must be provided so that the extracted air exchanges heat with cooler air, which, according to this document, is the air flowing in the radially peripheral secondary vein.

[0012] The heat exchanger consists of a finned tube positioned within the secondary flow. This solution presents several disadvantages, including an aerodynamic impact on the airflow within the secondary flow and an increase in the turbomachine's mass due to the presence of this finned tube.

[0013] The invention aims to provide a pressurization system in which the heat exchange means are designed to have less impact on the efficiency of the turbomachine than the prior art.

[0014] DESCRIPTION OF THE INVENTION

[0015] The invention relates to an aircraft turbomachine having the characteristics of claim 1.

[0016] The invention also has at least one of the following optional features, taken individually or in combination.

[0017] The turbomachine includes a pressurization cavity external to said lubrication chamber, the pressurization cavity and the chamber being separated by said at least one wall provided with a sealing joint to the chamber, and all or part of the pressurized air cooled by the exchanger is directed into said pressurization cavity so as to pressurize the lubrication chamber.

[0018] The aforementioned at least one wall of the lubrication chamber is a double- or triple-walled wall, delimiting a first volume in which the airflow drawn from the primary stream circulates, and a second volume that is in thermal contact with the first volume and in which a lubricating fluid circulates. In this respect, the wall in question may be triple-walled to delimit two superimposed chambers along the direction of the wall's thickness, forming the first and second volumes respectively. Alternatively, it may simply be a double-walled wall forming the first volume for the circulation of the pressurized airflow, the second volume then being partially delimited by the double-walled wall and the other walls of the chamber, since this second volume corresponds to that of the lubrication chamber.In this latter case, the lubricating fluid simply flows over the inner surface of this double-walled enclosure. The first and second volumes are separated by a sealed wall capable of conducting heat from the first volume to the second volume.

[0019] The watertight wall has a plurality of ribs that extend into one or the other of the first and second volumes.

[0020] The heat exchanger extends in the form of a single section, or of several sections spaced apart within said wall of the enclosure, these sections, for example in the form of ring sections, being then preferentially coplanar.

[0021] The azimuthal extent is, for example, symmetrical with respect to a vertical axis of the turbomachine, with reference to Earth's gravity. However, a non-symmetrical solution remains conceivable, without departing from the scope of the invention.

[0022] The lubricating fluid circulates in the second volume by Earth's gravity.

[0023] The second volume includes at least one lubrication fluid outlet orifice which opens into the lubrication chamber in the direction of said at least one component of the turbomachine.

[0024] The second volume includes at least one lubrication fluid inlet port into which a lubrication fluid supply line opens.

[0025] At least one wall of the lubrication chamber projects beyond the rest of the lubrication chamber such that the lubrication fluid inlet is located outside the lubrication chamber. Alternatively, this lubrication fluid inlet, in the second volume, could be located inside the lubrication chamber.

[0026] The supply line comprises a series of first nozzles that open directly onto at least one component of the turbomachine, and a series of second nozzles that open into at least one inlet orifice of the second volume. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Other features and advantages of the invention will become apparent upon reading the detailed description that follows, for an understanding of which reference should be made to the attached figures, among which:

[0028] - [Fig. 1] is a schematic axial section representation of an aircraft turbomachine comprising a pressurized air circuit made according to the invention;

[0029] - [Fig. 2] is a larger scale detail showing part of the pressurized air circuit, including a heat exchanger for cooling the airflow taken from the primary duct of the turbomachine;

[0030] - [Fig. 3] represents a front view of part of a wall forming the heat exchanger;

[0031] - [Fig- 4] represents a view similar to that of figure 2, according to another preferred embodiment of the invention;

[0032] - [Fig. 5] represents a view similar to that of figure 3, according to an alternative.

[0033] DETAILED DESCRIPTION OF SPECIFIC METHODS OF IMPLEMENTATION

[0034] Figure 1 shows a turbomachine 10 of an aircraft.

[0035] The turbomachine 10 comprises, moving away from its main axis A, a low pressure shaft 12, a high pressure shaft 14, a primary air flow 16, an intermediate casing 18, a secondary air flow 20 and an outer casing 22.

[0036] The intermediate casing 18 has a radially internal wall 24 delimiting the outside of the primary vein 16 and a radially external wall 26 delimiting the inside of the secondary vein 20. The outer casing 22 has a radially internal wall 28 delimiting the outside of the secondary vein 20.

[0037] The primary vein 16 comprises, from upstream to downstream according to the direction of air flow in it, i.e. here from left to right referring to figure 1, a low pressure compressor 30, a high pressure compressor 32, a combustion chamber 34, a high pressure turbine and a low pressure turbine (not shown in figure 1).

[0038] The turbomachine 10 also includes air circuits distributed inside it to cool several components of the turbomachine.

[0039] Among these circuits, a pressurized air circuit 40 is designed to both cool the low-pressure shaft 12, cool the discs of the high-pressure compressor 32, and supply pressurized air to enclosures 38 containing a lubricating fluid such as oil. Two of these enclosures 38 are schematically represented in Figure 1; some are located, for example, at the low-pressure shaft 12.

[0040] The pressurized air circuit 40 includes at least one air sampling point 42 which is located on an external casing 41 of the high-pressure compressor 32.

[0041] The air taken from the high-pressure compressor is at a pressure high enough to pressurize the oil chambers 38. However, the temperature of this air taken from the high-pressure compressor is too high to pressurize the chambers 38 and cool the low-pressure shaft 12, as well as the high-pressure compressor discs 32.

[0042] The pressurized air circuit 40 includes for this purpose a heat exchanger 44 allowing the temperature of the pressurized air that has been taken from it to be reduced.

[0043] This heat exchanger 44 is of the air-oil type, and the cold source is the lubricating fluid supplying the lubrication chambers 38.

[0044] According to the invention, and as schematically shown in Figures 2 and 3, the heat exchanger 44 is formed in at least one wall of a lubrication enclosure 38, namely in the thickness of this wall, occupying all or part of this wall.

[0045] As can be seen in more detail in Figure 2, a lubrication enclosure 38 delimits a closed volume in which is located a component of the turbomachine 10, such as, for example, here a bearing 50 for guiding the rotation of one of the two shafts 12, 14.

[0046] The lubrication enclosure 38 comprises fixed walls 52 connected to the stationary parts of the turbomachine, and movable walls 54 connected here to the shaft 12, 14. The fixed walls 52 and the movable walls 54 are connected to each other by sealing joints 56, for example dynamic joints.

[0047] The heat exchanger 44 is formed in a wall 58 of the lubrication enclosure 38, which is preferably one of the fixed walls 52. It is an outer boundary wall of the enclosure 38.

[0048] According to a preferred embodiment, the wall 58 of the lubrication chamber 38 is a triple-skin wall, delimiting a first volume 60 in which pressurized air circulates, and a second volume 62 in which lubricating fluid circulates. Thus, three skins follow one another along the thickness direction of the wall 58, forming the first and second volumes 60 and 62, respectively.

[0049] Preferably, the second volume 62 is located in the wall 58, on the inner side of the lubrication chamber 38 relative to the first volume 60, which is located towards the outside of the lubrication chamber. In an alternative solution, the wall 58 is simply double-walled to delimit the first volume 60, and the second volume 62 can simply be the volume of the chamber 38. In this alternative, the simplified wall 58 therefore does not need to provide a separate volume for the circulation of the lubricating fluid, which can flow along the inner face of this double wall to perform the heat exchange function with the pressurized airflow, before being reused for the lubrication function of the component 50.

[0050] In the triple-skin design, the first volume 60 and the second volume 62 are separated by a watertight wall 64 forming part of the wall 58. This watertight wall 64, corresponding to the intermediate skin, is intended to prevent any mixing of fluids between the first volume 60 and the second volume 62. It is located between an outer skin 64a and an inner skin 64b, these three skins being substantially parallel to each other, and spaced from each other along the direction of the thickness of the wall 58 which they constitute.

[0051] The central sealed wall 64, which delimits the two volumes 60 and 62 on either side, is made of a thermally conductive material to allow heat transfer from the first volume to the second volume 62. As shown in Figure 3, the sealed wall 64 may include ribs 66 extending into the first volume 60 and / or the second volume 62. The ribs 66, which extend along the thickness of the double- or triple-skinned wall 58, are designed to facilitate heat exchange between the pressurized airflow circulating in the first volume 60 and the lubricating fluid circulating in the second volume 62.

[0052] As can be seen in figure 2, the enclosure 38 is supplied with lubricating fluid by a pipe 68 which has first spray nozzles 70, which open towards the bearing 50 to be lubricated.

[0053] The supply of the second volume 62 with lubricating fluid is carried out via the conduit 68, which has a branch 72 supplying second nozzles 74, these second nozzles 74 opening into the second volume 62.

[0054] The second volume 62 includes at least one lubrication fluid inlet 76, through which the lubrication fluid is supplied. Preferably, the second nozzles 74 open into said at least one inlet 76, each nozzle 74 being able to be associated with a separate inlet 76.

[0055] The second volume 62 also includes at least one outlet 78, through which the lubricating fluid which has exchanged heat with the pressurized airflow exits the second volume 62.

[0056] As shown in Figure 2, and according to a preferred embodiment, the outlet orifice 78 opens in the direction of the bearing 50 to be lubricated, although other orientations can be considered, without departing from the scope of the invention.

[0057] Thus, all the lubricating fluid circulating in the line 68 and supplying the enclosure 38 is used to effectively lubricate the bearing 50, even though some of this fluid is also used to cool the pressurized airflow. Alternatively, all the lubricating fluid is introduced into the enclosure via the outlet(s) 78 of the second chamber, the first nozzles 70 then being no longer required. In this case, some of the fluid is directly sprayed onto the bearing 50 for lubrication, while the other part, exiting the same outlet(s) 78, is simply discharged into the enclosure 38.

[0058] According to a preferred embodiment, the lubricating fluid flows into the second volume under the action of Earth's gravity.

[0059] For this purpose, the location of the wall 58 in the turbomachine is defined so that this wall 58 is located vertically above the main axis A of the turbomachine 10, with said at least one inlet orifice 76 located at an external radial end of the wall 58, and said at least one outlet orifice 78 located at an internal radial end of the wall 58. More generally, said at least one inlet orifice 76 is radially further away from the main axis A of the turbomachine 10 than said at least one outlet orifice 78.

[0060] According to the embodiment shown in Figure 2, said at least one inlet orifice 76 is located radially inside the enclosure 38.

[0061] According to an alternative embodiment shown in Figure 4, said at least one inlet orifice 76 is located radially outside the enclosure 38. For this purpose, the external radial end of the wall 58 protrudes radially from the radially external fixed wall 52 of the enclosure 38. This alternative is advantageous in terms of mounting and accessibility of the second nozzles 74 supplying the second volume 62 of the wall 58 with lubrication fluid.

[0062] In the example shown in Figure 4, the heat exchanger 44 within the wall 58 is shaped like a single ring segment centered on the main arc A of the turbomachine 10. This segment can be symmetrical with respect to a vertical axis of the turbomachine 10, relative to Earth's gravity, with this vertical axis intersecting the main axis A of the turbomachine 10. In other words, this single ring segment formed by the exchanger 44 within the wall 58 is, for example, symmetrical with respect to a vertical and axial median plane PI of the turbomachine, but this is not required. This single ring segment formed by the exchanger 44 is, for example, entirely above the axis A, as shown in Figure 4.Thus, the azimuthal extent of the heat exchanger 44, that is, the angle centered on the principal axis A of the turbomachine 10 which delimits the portion of the wall 58 with a double or triple skin, is, for example, less than 180 degrees. However, angular extents greater than 180 degrees can be considered for the heat exchanger 44 within the same wall 58, particularly when this heat exchanger 44 is formed by several annular sections spaced circumferentially from one another, as in the variant shown in Figure 5. The wall 58 can have different shapes, for example, a slightly convex shape in the upstream direction of the turbomachine. A flat shape may be preferred, particularly to facilitate the construction of the double or triple skin of the wall 58.

[0063] In this variant, a heat exchanger 44 is indeed provided, formed by two ring segments 44a, 44b, circumferentially spaced from each other and both centered on axis A. The first segment 44a is an upper segment, arranged above axis A, with an angular extent of less than 180 degrees. The second segment 44b is a lower segment, arranged below axis A, and also with an angular extent of less than 180 degrees. If the shape of the enclosure wall 58 is provided to be flat, the two heat exchanger segments 44a, 44b, which therefore correspond to areas of the double- or triple-skinned wall 58, are then coplanar, that is to say, arranged in the same plane as this wall 58. This plane is preferably orthogonal to axis A, but a plane inclined with respect to axis A is also possible.

[0064] More specifically, with reference to Figure 5, the proposed design still relies on the movement of the lubricating fluid, the oil, by gravity. The branch 72 includes a first supply rail 80, which supplies oil to a first series of upper nozzles 74, cooperating with inlet ports located on the upper outer periphery of the second volume 62 of the upper heat exchanger section 44a. The ends of this first rail 80 communicate with a second supply rail 82, which supplies oil to a second series of lower nozzles 74, cooperating with inlet ports located on the upper inner periphery of the second volume 62 of the lower heat exchanger section 44b. This second series of nozzles 74 can extend over the circumferential edges of the lower heat exchanger section 44b, as shown in Figure 5.The oil flowing through the lower heat exchanger section 44b is discharged to the bottom of the enclosure 58, to return to a recovery pump in the engine oil circuit. The oil flowing through the upper heat exchanger section 44a can be used to supply the bearing 50 as illustrated previously, if the air cooling and bearing oil supply are to be combined.

[0065] Numerous other configurations are possible, such as having only a single heat exchanger section within wall 58, in its lower part. This configuration is equivalent to retaining only the lower section 44b of the mode shown in Figure 5.

[0066] In all cases, after being cooled by the oil in chamber 38 within the heat exchanger 44 integrated into wall 58, all or part of the air drawn from the compressor is directed to the outside of the seals of this same chamber, in order to pressurize the chamber with an external pressure greater than the pressure inside the chamber. As is typical, since the seals are not perfectly airtight, the pressure differential across the seals creates an airflow entering the chamber through the seals, thus preventing oil leaks from the seals outside the chamber.

[0067] In other words, the turbomachine has a pressurization cavity 39 external to the lubrication chamber 38. The pressurization cavity 39 and the lubrication chamber are separated by the chamber wall 58, which is equipped with one or more seals 56. Furthermore, all or part of the pressurized air 43 cooled by the heat exchanger 44 is directed into said pressurization cavity 39, as shown schematically in Figure 2. This effectively allows the chamber 38 to be pressurized by an external air pressure higher than the pressure inside the chamber 38, via the seal(s) 56, in the conventional manner described previously.

[0068] Of course, various modifications can be made by a person skilled in the art to the invention described above, solely by way of non-limiting examples, the scope of which is defined by the appended claims. In particular, the elements of the various preferred embodiments and their alternatives are interchangeable and / or combinable. Furthermore, it should be noted that the flow of pressurized air supplying the heat exchanger integrated into the lubrication enclosure wall can be regulated by any means, such as a controlled valve. The controlled valve can provide a selection between two inlets, each connected to an air sampling point, for example, a first inlet connected to a first air sampling point 42 located on an external housing 41 of the high-pressure compressor 32, and a second inlet connected to a second air sampling point located downstream of the low-pressure compressor 30.In this configuration, at low engine speeds, the controlled valve selects the first air intake point 42, i.e., on the high-pressure compressor, in order to significantly increase the available pressures for pressurizing the chambers and cooling the high-pressure compressor discs. At high engine speeds, the controlled valve will select the second air intake point located downstream of the low-pressure compressor, as the air pressure from this second point is sufficient at high engine speeds to pressurize the chambers and cool the high-pressure compressor discs.

[0069] Alternatively, the controlled valve can be a variable-opening valve with a single inlet connected to an air intake point 42 located on an external housing 41 of the high-pressure compressor 32. Controlling the valve opening allows for managing the pressure drop in the air intake circuit supplying the heat exchanger 44 and modulating the source pressure to meet the precise requirements. Specifically, the valve can be fully open at idle to meet pressure and cooling needs, and partially closed at high engine speeds to minimize the impact on the high-pressure compressor's efficiency and therefore the engine's specific fuel consumption. This improves air cooling in the heat exchanger 44 since there is less airflow to cool.

Claims

DEMANDS 1. Aircraft turbomachine (10) comprising a primary airflow channel (16) in which a low-pressure compressor (30) and a high-pressure compressor (32) are arranged, at least one lubrication chamber (38) for at least one component (50) of the turbomachine (10), a pressurized air circuit taking an airflow from the primary channel (16) at the high-pressure compressor, which supplies said lubrication chamber (38), in which the pressurized air circuit includes a heat exchanger (44) for cooling the airflow taken from the primary channel (16), characterized in that the heat exchanger (44) is formed in at least one wall (58) of the lubrication chamber (38), and in that all or part of the pressurized air (43) cooled by the exchanger (44) is directed so as to pressurize the lubrication chamber (38).

2. Turbomachine according to the preceding claim, characterized in that it comprises a pressurization cavity (39) external to said lubrication chamber (38), the pressurization cavity (39) and the chamber being separated by said at least one wall (58) provided with a sealing gasket (56) of the chamber, and in that all or part of the pressurized air (43) cooled by the exchanger (44) is directed into said pressurization cavity (39) so as to pressurize the lubrication chamber (38).

3. Turbomachine (10) according to claim 1 or 2, characterized in that said at least one wall (58) of the lubrication enclosure (38) is a double or triple skin wall, delimiting a first volume (60) in which the airflow taken from the primary channel (16) circulates, and a second volume (62) which is in thermal contact with the first volume (60) and in which a lubricating fluid circulates.

4. Turbomachine (10) according to the preceding claim, characterized in that the first volume (60) and the second volume (62) are separated by a sealed wall (64) capable of conducting heat from the first volume (60) to the second volume (62).

5. Turbomachine (10) according to the preceding claim, characterized in that the sealed wall (64) carries a plurality of ribs (66) which extend into one and / or the other of the first volume (60) and the second volume (62).

6. Turbomachine (10) according to any one of the preceding claims, characterized in that the heat exchanger (44) extends in the form of a single section, or of several sections (44a, 44b) spaced apart from each other within said wall (58).

7. Turbomachine (10) according to the preceding claim, characterized in that the azimuthal extent is symmetrical with respect to a vertical axis of the turbomachine (10), with reference to Earth's gravity.

8. Turbomachine (10) according to any one of claims 4 to 7 combined with claim 3, characterized in that the lubricating fluid circulates in the second volume (62) by terrestrial gravity.

9. Turbomachine (10) according to any one of claims 4 to 8 combined with claim 3, characterized in that the second volume (62) has at least one lubricating fluid outlet (78) which opens into the lubrication chamber (38) in the direction of said at least one component (50) of the turbomachine (10).

10. Turbomachine (10) according to any one of claims 4 to 9 combined with claim 3, characterized in that the second volume (62) comprises at least one lubrication fluid inlet port (76) into which a lubrication fluid supply line (68) opens to supply the lubrication chamber (38).

11. Turbomachine (10) according to the preceding claim, characterized in that said at least one wall (58) of the lubrication chamber (38) protrudes from the rest of the lubrication chamber (38), in such a way that the lubrication fluid inlet port (76) is located outside the lubrication chamber (38).

12. Turbomachine according to claim 10 or 11, characterized in that the supply conduit (68) comprises a series of first nozzles (70) which open directly onto said at least one component (50) of the turbomachine (10) and a series of second nozzles (74) which open into said at least one inlet orifice (76) of the second volume (62).

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