Optimized heat exchanger with ejector for turbomachine

Abstract

The invention provides a heat exchanger (4) for an air stream of a turbomachine (2), comprising a heat exchange zone (6) provided with oil passages and a heat exchange passage for a first air flow (P), characterized in that the heat exchanger further comprises a jet pump-type ejector (40), configured to project a second air flow (S) joining the first air flow, said ejector being formed integrally with the heat exchange zone.

Description

[0001] Description

[0002] OPTIMIZED HEAT EXCHANGER WITH EJECTOR FOR TURBOMACHINE

[0003] technical field

[0004] The invention relates to the field of turbomachinery heat exchangers. More specifically, the invention proposes an air / oil heat exchanger for a turbomachinery.

[0005] Previous art

[0006] Conventionally, in the field of turbomachinery, it is well known that under certain specific conditions, such as low speeds or insufficient incoming airflow, the airflow required for effective cooling can be compromised. For example, when waiting in a parked position, idling on the ground, or driving in hot weather, the natural airflow to the cooling system may prove insufficient. In such situations, it becomes crucial to artificially increase the airflow to maintain the effectiveness of oil cooling.

[0007] To meet this requirement, it is generally proposed to integrate a jet-type ejector downstream of the heat exchanger within a scoop or annular airflow channel. This type of ejector uses a secondary airflow to accelerate the primary airflow, thereby improving the airflow rate through the exchanger. An example of such an arrangement is described in published patent document WO 2015 / 197974 A1, which discloses the integration of a jet-type ejector into an air duct located downstream of the heat exchanger.

[0008] However, integrating the jet nozzle downstream of the heat exchanger as proposed in the document presents several drawbacks. Firstly, this configuration is bulky and requires a larger and heavier pipe to guide the flow downstream of the exchanger, which complicates assembly and can increase the overall weight and affect performance. Secondly, the airflow through the heat exchanger matrix is ​​not uniform. Because the secondary flow drive is concentrated on a single injector bank, this can lead to an uneven distribution of the secondary flow, thus limiting overall cooling efficiency.

[0009] Summary of the invention

[0010] Technical problem

[0011] The invention aims to provide a heat exchanger that minimizes aerodynamic losses while optimizing heat exchange between air and oil, in order to guarantee efficient cooling even when the air flow entering the exchanger is insufficient, and this in a small footprint without compromising the efficiency of the turbomachine.

[0012] Technical solution

[0013] The invention is the result of technological research aimed at significantly improving aircraft performance and, in this respect, contributes to reducing the environmental impact of aircraft. To this end, the present invention relates to a heat exchanger for an air stream of a turbomachine, comprising a heat exchange zone provided with oil passages and a heat exchange passage for a first air stream, remarkable in that the heat exchanger further comprises a jet-trigger ejector, configured to project a second air stream joining the first air stream, said ejector being directly formed with the heat exchange zone.

[0014] According to an advantageous embodiment of the invention, the ejector extends across the heat exchange zone parallel to a direction of circulation of the first airflow.

[0015] According to an advantageous embodiment of the invention, the ejector comprises a proximal part extending transversely to the first airflow and a distal part extending parallel to said first airflow.

[0016] According to an advantageous embodiment of the invention, the ejector comprises an elbow connecting the proximal and distal parts, said elbow being disposed at a substantially central portion of the heat exchange zone. According to an advantageous embodiment of the invention, the distal part extends to the center of the heat exchange zone.

[0017] According to an advantageous embodiment of the invention, the distal part comprises a first external face extending straight along the first airflow, and a second external face extending inclined with respect to said first airflow.

[0018] According to an advantageous embodiment of the invention, the second airflow passes through the heat exchange zone exclusively at the ejector.

[0019] According to an advantageous embodiment of the invention, the ejector comprises a distal end forming an outlet for the second airflow, disposed outside the heat exchange zone.

[0020] According to an advantageous embodiment of the invention, the distal part has a longitudinal profile converging between the elbow and the distal end.

[0021] According to an advantageous embodiment of the invention, the distal end is distant from the heat exchange zone by at most one quarter of a total longitudinal extent of said heat exchange zone along the first airflow.

[0022] According to an advantageous embodiment of the invention, the ejector extends continuously without change of direction in the heat exchange zone between approximately half of a longitudinal extent of the heat exchange zone and an outlet of the first airflow from said heat exchange zone.

[0023] According to an advantageous embodiment of the invention, the ejector extends longitudinally along the first airflow in a convergent section of the heat exchange zone.

[0024] According to an advantageous embodiment of the invention, the heat exchange zone comprises a diverging section along the first airflow upstream of the ejector.

[0025] According to an advantageous embodiment of the invention, the heat exchange zone comprises heat exchange surfaces forming the heat exchange passage for the first airflow, the ejector being directly formed with said heat exchange surfaces. The invention also relates to an aircraft turbomachine, notable in that it comprises a heat exchanger according to the invention.

[0026] It is understood that each detail of one embodiment above can be combined with each other detail of the other embodiments.

[0027] Benefits provided

[0028] Integrating the jet-type ejector directly into the heat exchanger optimizes space and reduces the overall mass while improving cooling efficiency. By projecting a second airflow that joins the first, the ejector creates a shearing effect that generates effective suction within the heat exchange zone, thus ensuring improved ventilation even when the incoming airflow is insufficient.

[0029] Furthermore, injecting the second airflow downstream of the first airflow outlet, from the heat exchange zone and extending to a quarter of the heat exchanger's longitudinal length, ensures a homogeneous airflow in this area, improving cooling performance while maintaining the system's compactness. In addition, the aerodynamic design of the ejector's distal portion reduces pressure drop, thus contributing to increased thermal efficiency.

[0030] Brief description of the drawings

[0031] Figure 1 illustrates a schematic cross-sectional view of an aircraft turbomachine comprising a heat exchanger according to the present invention;

[0032] Figure 2 shows a schematic longitudinal cross-sectional view of the heat exchanger of Figure 1, incorporating a trumpet-type jet ejector directly formed with said exchanger.

[0033] Detailed description of the implementation methods

[0034] The dimensions of the figures are not to scale and in particular the thicknesses or dimensions are exaggerated to facilitate the reading of the figures.

[0035] In this description, the term "longitudinal" refers to the direction of airflow through the object in question. In other words, it refers to the orientation parallel to the path of the airflow, allowing the arrangement or characteristics of the elements to be described according to their alignment with this direction of flow.

[0036] Figure 1 illustrates a schematic cross-sectional view of a turbomachine 2 installed under the wing of an aircraft.

[0037] In the upstream part of the turbomachine 2 is a propeller 14 driven in rotation by a turbine 16, via a speed reducer 18. The rotation of the propeller 14 generates a secondary airflow F2 which provides propulsion for the aircraft.

[0038] The turbine 16 receives combustion gases from a combustion chamber which is supplied with air by an internal airflow F1, corresponding to a primary airflow F1 which enters through an inlet duct 22 which is placed immediately downstream of the propeller 14 at the beginning of a cowling 24 of the turbomachine 2, and which then circulates through a primary airflow duct 20.

[0039] The reducer 18 is supplied with lubricant by a lubricant circuit 26 which essentially comprises pipes 28, a pump 30 and a heat exchanger 4 intended to cool the lubricant, which is preferably oil circulating in the speed reducer 18.

[0040] The cooling air of the heat exchanger 4 is preferably taken downstream of the inlet duct 22. For this purpose, an air inlet slot 34 can be used, for example, by being placed at the level of the duct 20 of the turbomachine 2, downstream of the inlet duct 22, to supply a supply duct 36 which supplies a first air flow P to the heat exchanger 4 housed in an internal compartment 37 of the turbomachine 2, comprising an air duct 38 preferentially forming a scoop 38 enlarged in order to receive said heat exchanger 4.

[0041] The exchanger 4 can be disposed in the scoop 38, or can alternatively be disposed in an annular vein in which said exchanger 4 can extend continuously over 360° or in an interrupted manner forming a plurality of angular sectors.

[0042] The turbomachine 2 includes an exhaust duct 39, placed downstream of the heat exchanger 4 in order to prolong the air circulation in the latter. In this configuration, at high speed, during a long-duration flight, or in very cold conditions, the air entering the air inlet slot 34, being conveyed by the supply line 36 through the heat exchanger 4 and exhausted by the exhaust duct 39, generally cools the heat exchanger 4 and the lubricant passing through it sufficiently.

[0043] On the other hand, at low speed, or under conditions where the airflow naturally reaching the air supply duct 36 is insufficient, for example when waiting in a parked position, idling on the ground or driving in hot weather, it proves useful to accelerate the airflow in the heat exchanger 4.

[0044] To this end, the present invention proposes integrating a jet-type ejector 40 directly into the heat exchanger 4, configured to project a second airflow S joining the first airflow P. The design of the heat exchanger 4 will be detailed along Figure 2 in this description. The ejector 40 includes upstream (along the second airflow S) a sampling duct 42 connected to an injector 44, preferably corresponding to a compressor 44 of the turbomachine 2. Preferably, the second airflow S inside the sampling duct 42 can be opened or closed by a valve 46.

[0045] In this configuration, the injection of the second airflow S accelerates the first airflow P and consequently, when necessary, increases the flow rate through the heat exchanger 4, resulting in improved cooling. Advantageously, integrating the ejector 40 directly within the heat exchanger 4 further compacts the assembly while also enhancing oil cooling.

[0046] Figure 2 shows a schematic longitudinal cross-sectional view of heat exchanger 4 from Figure 1.

[0047] The exchanger 4 includes a heat exchange zone 6 provided with oil passages (visible in figure 1) with, preferably, heat exchange surfaces (not shown) forming a heat exchange passage for the first air flow. Advantageously, the ejector 40 is directly formed with the heat exchange zone 6, and more preferably formed with the heat exchange surfaces.

[0048] Preferably, exchanger 4 is obtained by additive manufacturing, and more preferably by selective powder bed fusion.

[0049] We can see that the ejector 40 comprises a proximal part 40.1 extending transversely to the first airflow P and a distal part 40.2 extending parallel to said first airflow.

[0050] Preferably, the ejector 40 includes an elbow 40.3 connecting the proximal part 40.1 and the distal part 40.2. The elbow 40.3 is preferably located at a substantially central portion 6.1 of the heat exchange zone 6.

[0051] In this configuration, the ejector 40 can extend continuously without changing direction in the heat exchange zone 6 between approximately half of a longitudinal extent L of this zone 6 up to an outlet 6.2 of the first airflow P from said heat exchange zone 6. This advantageously ensures a laminar flow of the second projected airflow S, without disturbing the first airflow P inside the heat exchange zone 6.

[0052] The heat exchange zone 6 preferably includes a diverging section 6.3 along the first airflow P upstream of the ejector 40, and a convergent section 6.4 downstream of the elbow 40.3 and in which the distal part 40.2 extends parallel to the first airflow P.

[0053] The converging section 6.4 is entirely traversed by the distal part 40.2 of the ejector 40, and this, up to a distal end 40.4 of said ejector 40 forming an outlet 40.4 for the second airflow S.

[0054] As illustrated, outlet 40.4 can be located outside the heat exchange zone 6. For this purpose, ejector 40 opens downstream of said zone 6, along the first airflow P. In an alternative not shown, outlet 40.4 can be located within the heat exchange zone 6, upstream of outlet 6.2 of the first airflow P. Preferably, the distal end 40.4 is located from the heat exchange zone 6, and more precisely from outlet 6.2, by no more than one-quarter of a total longitudinal length L of said zone 6 along the first airflow P. In this configuration, the distal end 40.4 can be positioned downstream of zone 6, at the same level as outlet 6.2, and up to one-quarter of the total longitudinal length L.

[0055] Advantageously, the ejector 40 allows a shearing effect to be created between the second airflow S from the injector and the first airflow P at the outlet of the exchanger 4, thus generating a suction effect of air through the heat exchange zone 6. This makes it possible to force ventilation of the exchanger 4 in conditions where oil cooling is required, or when the inlet pressure is not high enough relative to the outlet pressure to ensure optimal flow.

[0056] Furthermore, the injection of the second airflow S directly downstream of outlet 6.2 and at most one quarter of the longitudinal extent L, ensures a uniform flow, thus improving cooling performance.

[0057] Figure 2 shows that the distal part 40.2 has a convergent longitudinal profile between the elbow 40.3 and the distal end 40.4. This allows the second airflow S to be concentrated and smoothed further in order to unify the intersection of the two flows P and S, and thus to minimize aerodynamic disturbances within the heat exchange zone 6.

[0058] The distal part 40.2 includes a circumferential contour formed by two opposite faces 40.5 and 40.6, comprising a first external face 40.5 extending preferably in a straight line along the first airflow P, and a second external face 40.6 extending in an inclined manner with respect to the flow P, said inclination being, preferably, between 0° and 30°.

[0059] Advantageously, faces 40.5, 40.6 provide the ejector with an aerodynamic shape that effectively reduces pressure losses within the heat exchange zone 6.

[0060] The elbow 40.3 and the distal part 40.2 of the ejector 40 can be positioned at the center of the heat exchange zone 6, corresponding to the center of a cross-section (not shown) along a cut perpendicular to the first airflow P. This ensures a homogeneous convergence of the two flows P and S at the center of the exhaust duct 39, thus promoting a uniform distribution of the heat exchange upstream in the exchanger 4.

[0061] Preferably, the exhaust duct 39 is formed with the exchanger 4 by additive manufacturing.

[0062] Advantageously, the second airflow S passes through the heat exchange zone 6 exclusively at the ejector 40. The integration of the ejector 40 within the exchanger 4 allows, on the one hand, for the efficient compaction of the assembly and, on the other hand, for the improvement of the heat exchange between the first airflow P and the oil in the exchanger 4, thanks to the acceleration of said first airflow P.

Claims

Demands 1. Heat exchanger (4) for an air stream (38) of a turbomachine (2), comprising a heat exchange zone (6) provided with oil passages and a heat exchange passage for a first air stream (P), characterized in that the heat exchanger (4) further includes a jet-type ejector (40) configured to project a second airflow (S) joining the first airflow (P), said ejector (40) being directly formed with the heat exchange zone (6), said ejector (40) extending continuously without change of direction in the heat exchange zone (6) between approximately half of a longitudinal extent of the heat exchange zone (6) and an outlet (6.2) of the first airflow (P) from said heat exchange zone (6).

2. Heat exchanger (4) according to claim 1, in which the ejector (40) extends through the heat exchange zone (6) parallel to a direction of circulation of the first airflow (P).

3. Heat exchanger (4) according to any one of claims 1 and 2, wherein the ejector (40) comprises a proximal part (40.1) extending transversely to the first airflow (P) and a distal part (40.2) extending parallel to said first airflow (P).

4. Heat exchanger (4) according to claim 3, in which the ejector (40) has an elbow (40.3) connecting the proximal part (40.1) and the distal part (40.2), said elbow (40.3) being disposed at a substantially central portion (6.1) of the heat exchange zone (6).

5. Heat exchanger (4) according to any one of claims 3 and 4, wherein the distal part (40.2) extends to the center of the heat exchange zone (6).

6. Heat exchanger (4) according to any one of claims 3 to 5, wherein the distal part (40.2) comprises a first external face (40.5) extending straight along the first airflow (P), and a second external face (40.6) extending inclined with respect to said first airflow (P).

7. Heat exchanger (4) according to any one of claims 1 to 6, wherein the second airflow (S) passes through the heat exchange zone (6) exclusively at the ejector (4).

8. Heat exchanger (4) according to any one of claims 1 to 7, wherein the ejector (40) includes a distal end (40.4) forming an outlet for the second airflow (S), disposed outside the heat exchange zone (6).

9. Heat exchanger (4) according to claims 4 and 8, wherein the distal part (40.2) has a longitudinal profile converging between the elbow (40.3) and the distal end (40.4).

10. Heat exchanger (4) according to any one of claims 8 and 9, wherein the distal end (40.4) is distant from the heat exchange zone (6) by at most one quarter of a total longitudinal extent (L) of said heat exchange zone (6) along the first airflow (P).

11. Heat exchanger (4) according to any one of claims 1 to 10, wherein the ejector (40) extends longitudinally along the first airflow (P) in a convergent section (6.4) of the heat exchange zone (6).

12. Heat exchanger (4) according to any one of claims 1 to 11, wherein the heat exchange zone (6) comprises a diverging section (6.3) along the first airflow (P) upstream of the ejector (40).

13. Heat exchanger (4) according to any one of claims 1 to 12, wherein the heat exchange zone (6) comprises heat exchange surfaces forming the heat exchange passage for the first airflow (P), the ejector (40) being directly formed with said heat exchange surfaces.

14. Aircraft turbomachine (2), characterized in that it comprises a heat exchanger (4) according to any one of claims 1 to 13.

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