Surface heat exchanger with additional outlet

Abstract

A surface heat exchanger (20) for an aircraft turbomachine (1) comprises a support wall (21), a panel (22) arranged substantially parallel to the support wall (21), a partition (23) connecting the wall (21) to the panel (22), the partition defining passages (24) between one another in which an air flow (F1) flows, and fins (25) located in the passages (24). The panel has a central portion (26) parallel to the wall (21) and a downstream portion (29) inclined with respect to the wall (21), the downstream portion having an upstream end (29A) connected to the central portion (26) and a downstream end (29B) positioned at a distance (D2) from the wall (21) and delimiting, with the wall, a main outlet (SP) of the passages (24). The downstream portion (29) has fixed flaps (30i) arranged one behind the other to delimit, between one another, additional outlets (Sj) of the passages (24).

Description

Technical Field

[0001] This invention relates to the general field of aviation. In particular, it relates to surface heat exchangers for turbines and turbines comprising such heat exchangers. Background Technology

[0002] Turbines (especially those used in aircraft) include various components and / or equipment items that require lubrication and / or cooling, such as roller bearings and gears. Depending on the power of the components and / or equipment items, the heat released by these parts can be very high, and this heat is transferred through fluids and dissipated to available cooling sources within the aircraft.

[0003] It is known to equip turbines with one or more heat exchange systems to exchange heat between a lubricating fluid (typically oil) and a cooling source (air, fuel, etc.). Even different types of heat exchange systems exist, such as fuel-cooled oil coolers (FCOCs) and air-cooled oil coolers (ACOCs).

[0004] FCOC heat exchangers have a dual function: heating the fuel before combustion in the turbine's combustion chamber and cooling the oil heated by the turbine's heat dissipation. However, for safety reasons, fuel temperature is limited, so FCOC heat exchangers are insufficient to absorb all heat dissipation.

[0005] Additional cooling is achieved through ACOC heat exchangers (especially surface heat exchangers, SACOC). Surface heat exchangers are typically located in the secondary passages of a turbine and utilize the secondary airflow to cool the oil flowing through the turbine. These heat exchangers take the form of metallic surface elements to allow oil to pass through the passages. The secondary airflow is guided along fins supported by these surface elements, which increase the contact surface with the secondary airflow and facilitate heat absorption. However, a disadvantage of SACOC heat exchangers is that they disrupt the airflow, resulting in additional pressure losses in the associated secondary passages, which can affect turbine performance and fuel consumption.

[0006] SACOC heat exchangers have low aerodynamic thermal performance (the ratio between the heat dissipation on the secondary airflow side and the resulting pressure loss).

[0007] Furthermore, the cooling requirements for lubricating fluids are also increasing due to the higher rotational speed and power demands required to meet turbine specification trends.

[0008] Heat exchange systems (such as those described in FR-A1-3 096 444 and FR-A1-3 096 409) are known in which flow conditions are modified to ensure heat dissipation with optimal aerodynamic thermal performance, thereby contributing to reduced pressure loss. When these heat exchange systems are installed in the secondary passage of a turbine, they include shaped upstream and downstream walls that allow for better control of the airflow entering and leaving the heat exchanger. More specifically, the upstream wall has a widening profile to slow the airflow entering the heat exchange space of the heat exchanger, and the downstream wall has a converging profile to accelerate the airflow leaving the heat exchanger.

[0009] However, the "converging" profile of the wall at the heat exchanger outlet can still cause a portion of the airflow bypassing the heat exchanger (i.e., airflow that does not pass through the heat exchanger) to become turbulent in the flow recirculation zone. The profile of the wall at the heat exchanger outlet can be modified to reduce the degree of "convergence." However, the overall length of the heat exchanger is limited by the dimensions of the secondary passages where the heat exchanger is installed. Reducing the convergence of the outlet wall leads to a decrease in the central space of the heat exchanger, which is detrimental to heat exchange, and also causes premature acceleration of the outlet airflow, which is detrimental to the resistance of the surface heat exchanger. Summary of the Invention

[0010] The object of the present invention is to overcome this drawback by providing a surface heat exchanger that enables better control of the airflow leaving the exchanger.

[0011] Therefore, the present invention relates to a surface heat exchanger for an aircraft turbine, the surface heat exchanger comprising:

[0012] - Supporting wall,

[0013] - Panel, the panel is arranged roughly parallel to the supporting wall.

[0014] - A partition, configured to connect the support wall to the panel in a direction perpendicular to the support wall, the partition defining a passage between the partitions, through which a first airflow flows, the partitions being generally parallel to each other and parallel to a first flow direction of the first airflow.

[0015] - Fins, the fins are located in the passage and extend in a manner that is generally parallel to each other and parallel to the first flow direction, the fins being designed to be swept by the first airflow.

[0016] The panel includes:

[0017] -The central portion, which is approximately parallel to the supporting wall and at a first distance from the supporting wall.

[0018] - Downstream portion, the downstream portion having a generally inclined orientation relative to the support wall, the downstream portion including an upstream end and a free downstream end, the upstream end being connected to the central portion, the free downstream end being a second distance from the support wall, and the free downstream end together with the support wall defining the main outlet of the passage, the second distance being less than the first distance.

[0019] According to the invention, the downstream portion includes at least two fixed flaps arranged from upstream to downstream with one flap behind the other, and configured to define at least one additional exit from the passage between the fixed flaps.

[0020] Therefore, this solution enables the achievement of the aforementioned objectives. In particular, the additional outlets that provide a pathway for the first airflow compensate for excessive convergence in the downstream section of the heat exchanger. The first airflow passing through these additional outlets, which are closer to the panel than the main outlet, prevents the second airflow from bypassing the heat exchanger. Increasing the number of additional outlets also allows the first airflow to flow through the surface heat exchanger at a uniform speed across the entire height of the surface heat exchanger.

[0021] Surface heat exchangers may include one or more of the following features, either individually or in combination:

[0022] - The number of flaps ranges from two to five.

[0023] - Each flap in the flaps extends in a plane inclined at a predetermined angle relative to the supporting wall.

[0024] - The predetermined angle of the flap decreases from the center portion to the main outlet.

[0025] - The value of each angle in the flaps ranges from 5° to 45°.

[0026] - Additional exits, or each additional exit, are limited by a height that is less than or equal to the second distance.

[0027] - The radial height, or each radial height and the second radial distance, are both between 5% and 60% of the first distance.

[0028] - Each flap in the flaps is connected to the support wall by at least a portion of a fin and / or by a support element that rises between the support wall and the flap.

[0029] - At least a portion of the flap includes a downstream edge located near the upstream edge of an adjacent flap, the upstream and downstream edges being arranged generally in the same plane perpendicular to the support wall.

[0030] - Surface heat exchangers are manufactured using additive manufacturing.

[0031] - The surface heat exchanger is machined and / or brazed.

[0032] The present invention also relates to a surface heat exchanger having at least one of the foregoing features. Attached Figure Description

[0033] Other features and advantages of the invention will become apparent from the following detailed description, and with reference to the accompanying drawings, in order to understand it:

[0034] [ Figure 1 ] Figure 1 This is an axial cross-sectional view of an example turbine to which the present invention is applied;

[0035] [ Figure 2 ] Figure 2 This is a perspective view of an embodiment of a surface heat exchanger;

[0036] [ Figure 3 ] Figure 3 A partial view of a heat exchanger including a finned panel is shown;

[0037] [ Figure 4 ] Figure 4 In the absence of the center section of the panel Figure 3 A perspective view of a heat exchanger;

[0038] [ Figure 5 ] Figure 5 This is an axial cross-sectional view of an embodiment of the heat exchange system according to the present invention;

[0039] [ Figure 6 ] Figure 6 An axial cross-section of a surface heat exchanger according to the present invention is shown; and

[0040] [ Figure 7 ] Figure 7 It is based on the present invention Figure 6 An axial cross-sectional view of a portion of a heat exchanger. Detailed Implementation

[0041] Figure 1 An axial cross-sectional view of a turbine with a longitudinal axis X to which the present invention is applied is shown. The turbine shown is a dual-flow turbine 1 intended for installation on an aircraft. Of course, the present invention is not limited to this type of turbine.

[0042] The dual-flow turbine 1 typically includes a gas generator 2, with a fan or fan module 3 installed upstream of the gas generator.

[0043] In this invention, the terms "upstream" and "downstream" are used with reference to their position relative to the flow axis of the gas in turbine 1 (here, along the longitudinal axis XX). "Longitudinal" or "longitudinally" refers to any direction parallel to the longitudinal axis XX.

[0044] The gas generator 2 includes a gas compressor assembly (hereinafter including a low-pressure compressor 4a and a high-pressure compressor 4b), a combustion chamber 5, and a turbine assembly (hereinafter including a high-pressure turbine 6a and a low-pressure turbine 6b). Typically, the turbine includes a low-pressure shaft 7 and a high-pressure shaft 8, the low-pressure shaft connecting the low-pressure compressor and the low-pressure turbine to form a low-pressure body, and the high-pressure shaft connecting the high-pressure compressor and the high-pressure turbine to form a high-pressure body. The low-pressure shaft 7, centered on the longitudinal axis, drives the fan shaft 9 via a gearbox 10. A rotary guide bearing is also used to guide the rotation of the low-pressure shaft 7 relative to the stationary structure of the turbine.

[0045] Fan 3 is covered by fan housing 11 and generates a primary airflow and a secondary airflow. The fan housing is supported by nacelle 12. The primary airflow flows through the gas generator 2 in the primary channel V1, and the secondary airflow flows in the secondary channel V2 surrounding the gas generator 2. The secondary airflow V2 is injected by secondary nozzle 13, which terminates the nacelle, while the primary airflow is injected to the outside of the turbine through injection nozzle 14 located downstream of the gas generator 2. In the following text, the fan housing and nacelle are considered as a single unit.

[0046] In this example of turbine construction, the guide bearing 15 and gearbox 10 must be lubricated and / or cooled to ensure turbine performance. The power generated by the guide bearing and gearbox is dissipated in fluid from a fluid supply source installed within the turbine, which lubricates and / or cools the various components and / or equipment of the turbine. Of course, other equipment items of the turbine generate significant amounts of heat, which must be drawn from the environment.

[0047] For this purpose, turbine 1 includes a surface heat exchanger 20 (hereinafter referred to as "exchanger 20") arranged in fan housing 11. Heat exchanger 20 is used to cool a fluid intended to lubricate and / or cool these components and / or equipment items. In this example, the fluid is oil, and the cold source for cooling the oil is the airflow circulating in turbine 1.

[0048] Reference Figures 2 to 7The heat exchanger 20 includes a support wall 21 extending in a longitudinal direction L parallel to the longitudinal axis XX. The support wall 21 is generally flat. The support wall 21 may not be completely flat but may be curved to follow the contour of the wall of the fan housing 11, which is designed to support the heat exchanger 20 and is generally cylindrical (with the longitudinal axis XX). The heat exchanger 20 may occupy the entire wall of the fan housing 11 or be arranged on a portion of the fan housing wall.

[0049] The exchanger 20 also includes a panel 22 extending along the longitudinal direction L for a predetermined length. The panel 22 is arranged substantially parallel to the support wall 21. The panel 22 is positioned above or below the support wall 21. Throughout the specification, the terms "above / outer" and "below / inner" are used with reference to the positioning relative to the plane on which the support wall 21 is arranged, in which case the plane XY includes the longitudinal axis XX and the transverse axis YY perpendicular to the longitudinal axis XX. "Transverse" or "laterally" refers to any direction parallel to the transverse axis YY, and "radial" or "radially" refers to any direction perpendicular to the plane XY.

[0050] like Figure 3 and Figure 4 As shown, panel 22 and support wall 21 are connected together by partitions 23. Each of these partitions 23 rises from support wall 21 in the radial direction R to panel 22 and extends in the longitudinal direction L. Although the partitions may have curved shapes, the partitions 23 are flat. The partitions 23 are arranged sequentially and regularly in the transverse direction T. The partitions are arranged parallel to each other to define a series of straight passages 24 between the partitions through which a first airflow F1 flows. This first airflow F1 corresponds to the secondary airflow F entering the secondary channel V2 and passing through a portion of the exchanger 20. The passages 24 formed by the partitions 23 are oriented in the first flow direction of the airflow F1. This flow direction corresponds to the longitudinal direction L.

[0051] The heat exchanger 20 also includes fins 25 arranged in the passage 24 such that the fins are swept across by the airflow F1. Although the fins may be curved, the fins 25 are preferably straight and flat. Figure 3 and Figure 4 As shown, the fins may also have discontinuous outer edges in the longitudinal direction L. Each fin in fin 25 rises in the radial direction R and extends in the flow direction of the airflow F1. More specifically, the fins 25 are arranged parallel to each other and parallel to the partition 23, and are uniformly arranged in each passage of the passage 24 in the transverse direction T.

[0052] refer to Figure 5 and Figure 6Panel 22 includes an inner surface 22A and an outer surface 22B. The inner surface 22A faces the support wall 21, such that it is also swept by the airflow F1 entering the exchanger 20. The outer surface 22B is swept by a second airflow F2. This second airflow F2 corresponds to the portion of the secondary airflow F that enters the secondary channel V2 and bypasses the exchanger 20. The airflow F2 flows on the outer surface 22B in a direction generally parallel to the longitudinal direction L.

[0053] In a preferred embodiment, panel 22 includes a central portion 26. The central portion 26 extends along a central length LC in a plane substantially parallel to the XY plane above support wall 21, the central length of which may be less than or equal to the length of fin 25. Specifically, as... Figure 6 As shown, the central portion is separated from the supporting wall 21 by a first predetermined distance D0 in the radial direction R. Furthermore, the central portion 26 extends along the transverse direction T in a width at least equal to the width of the partition 23. Alternatively, the central portion 26 may be inclined relative to the supporting wall 21, such that the panel 22 at least partially has a curved aerodynamic profile. The distance D0 between the central portion 26 and the supporting wall 21 may vary along the longitudinal direction L (see [reference]). Figure 3 and Figure 4 ).

[0054] In particular, such as Figure 5 and Figure 6 As shown, panel 22 also includes an upstream portion 27 located on the main inlet EP side of passage 24 of exchanger 20 (in the flow direction of secondary airflow F). The upstream portion includes a wall 28 having a gradually widening profile to guide and slow the airflow F1 entering passage 24. More specifically, the profile of wall 28 is generally corrugated or curved in a plane defined by the longitudinal direction L and the radial direction R. The upstream portion 27 may cover the downstream portion (not shown) of fin 25, and the upstream portion extends along an inlet length LE, which is less than the length LC of the central portion 26.

[0055] The upstream portion 27 also includes a free upstream end 27A, which, together with the support wall 21, defines the main inlet EP of the passage 24. This main inlet EP is defined in the radial direction R by a predetermined inlet distance D1. The value of the inlet distance D1 is preferably less than the distance D0, such that the airflow F1 decelerates upon entering the passage 24. The upstream portion 27 also includes a downstream end 27B opposite to the free upstream end 27A, such as… Figure 6 As shown. The downstream end 27B connects the upstream portion 27 to the upstream edge 26A of the central portion 26. The outer surface 27C of the upstream portion 27 has a continuous surface with the outer surface 26C of the central portion 26.

[0056] Reference Figure 6 Panel 22 also includes a downstream portion 29 located on the main outlet SP side of passage 24 of exchanger 20 (in the flow direction of airflow F1), and extending in the longitudinal direction L along an outlet length LS. This length LS is less than the length LC of the central portion 26. The downstream portion 29 is configured to guide and accelerate the airflow F1 exiting passage 24 of exchanger 20. The downstream portion is arranged in a plane extending in the transverse direction T with a width comparable to the widths of the upstream portion 27 and the central portion 26, and may cover the downstream portion (not shown) of fin 25. The downstream portion 29 has an angular orientation that is generally inclined relative to the plane XY on which the support wall 21 is arranged, forming a generally decreasing profile from the central portion 26 toward the support wall 21 (in the flow direction of airflow F1). The downstream portion 29 is provided with an upstream end 29A and a downstream end 29B, the upstream end connecting the downstream portion to the downstream edge of the central portion 26, and the downstream end 29B being a free end opposite to the upstream end 29A. The downstream end 29B is separated from the support wall 21 by a second predetermined distance D2, referred to as the outlet distance. This outlet distance D2 defines the main outlet SP of the passage 24 through which the airflow F1 flows. The value of distance D2 is less than the value of distance D0, and both the values ​​of distance D2 and distance D0 are measured in the radial direction R. The value of distance D2 is between 5% and 60% of the value of distance D0.

[0057] The central portion 26, the upstream portion 27, and the downstream portion 29 of panel 22 are integrally formed, for example, using additive manufacturing (or 3D printing) methods (e.g., selective melting on a powder bed).

[0058] In a preferred embodiment, the downstream portion 29 further includes fixed flaps 30i, where i = 1, ..., N, and N is an integer representing the maximum number of fixed flaps 30i. Figure 6 and Figure 7 As shown, these flaps 30i are arranged from upstream to downstream, one behind the other, from panel 22 toward support wall 21, so that the downstream portion 29 has a generally converging profile. The arrangement of two adjacent flaps 30i defines the additional exits Sj of passage 24, where j = 1, ..., M, where M is an integer representing the maximum number of additional exits.

[0059] The downstream portion 29 includes N flaps 30i, where N is between two and five, preferably between three and five, such that the number M of additional outlets Sj is between one and four, preferably between two and four. Each flap 30i has an upstream edge 31i and a downstream edge 32i opposite to the upstream edge 31i. Depending on the number N of flaps 30i, the downstream portion 29 includes at least one outer flap 301 and one inner flap 30N, as shown below. Figure 7 As shown. More specifically, an outer flap 301 is arranged upstream of any other flap 30i such that the upstream edge 311 of the outer flap represents the upstream end 29A of the downstream portion 29, which connects the downstream portion to the central portion 26. The outer flap 301 includes an outer surface 30C that is surface continuous with the outer surface 26C of the central portion 26. An inner flap 30N is arranged downstream of any other flap 30i such that the downstream edge 32N of the inner flap represents the free downstream end 29B of the downstream portion 29, which, together with the support wall 21, defines the main outlet SP of the passage 24.

[0060] Furthermore, the flaps 30i are arranged in a direction opposite to the radial direction R, such that the downstream edge 32i of the flaps 30i is located near the upstream edge 31i of the adjacent flaps 30i. More specifically, as Figure 7 As shown, the upstream edge 31i and downstream edge 32i of adjacent flaps 30i are arranged in the same plane perpendicular to the support wall 21 in the radial direction R.

[0061] In a preferred embodiment, each of the flaps 30i is arranged in a plane that extends in the lateral direction T over a width at least equal to the width of the passage 24 in which it is arranged.

[0062] like Figure 7 As shown, each of the flaps 30i is tilted relative to the support wall 21 at a predetermined angle 33i. The value of each predetermined angle 33i can vary between 0° and 45°. The values ​​of the angles 33i of two adjacent flaps define the opening of the additional outlet Sj. More specifically, when the value of the angle 33i of the upstream flap 30i (in the direction of airflow F1) is close to 0°, the flap 30i is arranged in a plane substantially parallel to the plane of the support wall 21. The additional outlet Sj is opened to reduce the flow rate of the airflow F1. Conversely, when the value of the angle 33i of the upstream flap 30i is close to 45°, the opening of the additional outlet Sj increases, and the flow rate of the airflow F1 also increases. Preferably, the value of each predetermined angle 33i is between 5° and 30°.

[0063] Furthermore, the angle 33i of the flap 30i can have different values, so that the additional outlet Sj can have different openings along the downstream portion 29.

[0064] In a preferred embodiment, the value of the predetermined angle 33i of the flap 30i decreases along the longitudinal direction L from the center portion 26 of the panel 22 toward the main outlet SP of the passage 24. Therefore, the outer flap 301 has a sufficiently small angle 331 to prevent the airflow F2 from separating downstream of the center portion 26 of the panel 22.

[0065] Furthermore, the presence of multiple adjacent flaps 30i prevents the downstream portion 29 from being lengthened, which reduces the length LC of the central portion 26, thus hindering heat exchange between the airflow F1 and the oil.

[0066] In one variant, the angle 33i of the flaps 30i all have the same value. The flaps 30i are all arranged in planes that are parallel to each other.

[0067] like Figure 7 As shown, the distance between the upstream edges 31i of two adjacent flaps defines the height Hj of the additional exit Sj. The values ​​of height Hj can be different from each other or the same as each other. On the other hand, all values ​​of height Hj are less than or equal to the value of the distance D2 that defines the main exit of passage 24.

[0068] Additionally, each height Hj of the additional exit is between 5% and 60% of the distance D0.

[0069] The exchanger 20 also includes support elements 34 that enable the flaps 30i to be attached to the support wall 21. Each support element 34 corresponds to a flap 30i and rises radially from the support wall 21. Therefore, the number of support elements 34 can be equal to the number N of flaps 30i in the downstream portion 29. Since the flaps 30i are inclined relative to the support wall 21, the support elements 34 have a generally trapezoidal shape. In a particular embodiment, some flaps 30i, including the outer flap 301, are attached to the support wall 21 via the downstream portion of the fin 25. In this example of the embodiment, the number of support elements 34 is less than the number N of flaps 30i. The support elements 34 can be thicker than the fins 25. The fins 25, the partitions 23, and the support elements 34 can be attached to the support wall 21 independently or together by brazing. Alternatively, the fins 25, the partitions 23, and the support elements 34 can be formed as a single integral piece with the support wall 21. Of course, the switch 20 as a whole can be manufactured by any other manufacturing method (such as machining, forging or brazing).

[0070] The heat exchanger 20 according to the invention has the particular advantage of making the flow velocity or circulation speed of the airflow F1 uniform over the entire distance D0.

[0071] Furthermore, the presence of multiple fixed flaps with different angular orientations allows for the elimination of the recirculation region of the airflow F2 bypassing the heat exchanger without increasing the outlet length LS. This reduces the drag caused by the heat exchanger.

Claims

1. A surface heat exchanger (20) for an aircraft turbine (1), the surface heat exchanger (20) comprising: - Support wall (21). - Panel (22), the panel being arranged parallel to the support wall (21), - A partition (23) configured to connect the support wall (21) to the panel (22) in a direction perpendicular to the support wall (21), the partition (23) defining a passage (24) between the partitions, a first airflow (F1) flowing in the passage, the partitions (23) being parallel to each other and parallel to a first flow direction of the first airflow (F1). - Fins (25), which are located in the passage (24) and extend in a manner parallel to each other and parallel to the first flow direction, the fins (25) being intended to be swept by the first airflow (F1). The panel includes: - A central portion (26) that is parallel to the support wall (21) and is a first distance (D0) from the support wall (21). - A downstream portion (29) having an orientation inclined relative to the support wall (21), the downstream portion (29) including an upstream end (29A) and a free downstream end (29B), the upstream end being connected to the central portion (26), the free downstream end being a second distance (D2) from the support wall (21), and the free downstream end together with the support wall (21) defining the main outlet of the passage (24), the second distance (D2) being less than the first distance (D0). The downstream portion (29) is characterized by comprising at least two fixed flaps (30i) arranged from upstream to downstream in such a manner that one is behind the other, and configured to define at least one additional outlet (Sj) between the fixed flaps that exits from the passage (24).

2. The surface heat exchanger (20) according to claim 1, characterized in that, The number (N) of fixed flaps (30i) is between two and five.

3. The surface heat exchanger (20) according to claim 1 or 2. Its features are, Each of the fixed flaps (30i) extends in a plane inclined at a predetermined angle (33i) relative to the support wall (21).

4. The surface heat exchanger (20) according to claim 3. Its features are, The value of the predetermined angle (33i) of the fixed flap (30i) decreases from the center portion (26) to the main outlet (SP).

5. The surface heat exchanger (20) according to claim 3. Its features are, The value of each of the predetermined angles (33i) of the fixed flap (30i) is between 0° and 45°.

6. The surface heat exchanger (20) according to claim 1 or 2. Its features are, The additional exit (Sj) or each additional exit is defined by a height (Hj), the value of which is less than or equal to the second distance (D2).

7. The surface heat exchanger (20) according to claim 6. Its features are, The height (Hj) or each height and the second distance (D2) are both between 5% and 60% of the first distance (D0).

8. The surface heat exchanger (20) according to claim 1 or 2, characterized in that, Each of the fixed flaps (30i) is connected to the support wall (21) by at least a portion of the fin (25) and / or by a support element that rises between the support wall (21) and the fixed flap (30i).

9. The surface heat exchanger (20) according to claim 1 or 2, characterized in that, At least a portion of the fixed flap (30i) includes a downstream edge (32i) located near the upstream edge (31i) of an adjacent fixed flap (30i), the upstream edge (31i) and the downstream edge (32i) being arranged in the same plane perpendicular to the support wall (21).

10. An aircraft turbine (1) comprising at least one surface heat exchanger (20) according to any one of claims 1 to 9.

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