Aircraft turbine engine

Abstract

The invention relates to a turbine engine (20) comprising a casing intended to improve aerodynamics and air flow management. The casing comprises an annular wall (1) comprising guiding micro-corrugations formed by alternating troughs (60) and crests (40). The micro-corrugations help to reduce turbulence, thereby stabilizing the air flow and improving the overall efficiency of the turbine engine (20).

Description

Casing for aircraft turbomachine technical field

[0001] The present invention relates to an aircraft turbomachine comprising a housing. The present invention also relates to a method of manufacturing such a turbomachine. Previous art

[0002] In turbomachinery, airflow management is crucial for optimizing performance and preventing malfunctions. However, certain components in the flow path, such as separation nozzles or stators, can generate disturbances. These elements can alter the stability of the airflow, thus affecting the overall performance of the machine. To meet this challenge, turbomachine casing design has evolved, both in terms of geometry and materials, with the aim of improving aerodynamics. Solutions based on conventional casings can sometimes prove limited in ensuring optimal flow management and maintaining high performance. Description of the invention

[0003] One object of the present invention is to provide an aircraft turbomachine that improves aerodynamics compared to the prior art.

[0004] To this end, an aircraft turbomachine is proposed, comprising: - a rotor to generate a main flow, - a separating nozzle to create a separation between a first stream and a second stream, originating from the main stream, and - a housing comprising an annular wall, said annular wall comprising a guiding micro-corrugation, formed by an alternation of troughs and ridges, each ridge and each trough extending axially from an upstream position to a downstream position, said upstream position coinciding with an inflection point of the annular wall, according to a predefined tolerance, said inflection point being axially aligned with a leading edge of said separating beak, according to a predefined tolerance.

[0005] These tolerances are preferably on the order of less than 5% of an average diameter of the annular wall, in particular less than 2%.

[0006] The turbomachine casing according to the invention offers several advantages. Indeed, during the division of the main flow at the separation nozzle into a first and a second flow, the inflection point formed on the annular wall plays a crucial role. It allows for local adaptation of the casing geometry to accommodate the flow deflection without creating discontinuities or excessive restrictions. This geometric adaptation aims to compensate for the obstruction introduced by the separation nozzle, which generally tends to reduce the available cross-sectional area for airflow. Such a reduction in cross-section can lead to flow disturbances, including local accelerations, recirculation zones, and pressure losses.From this inflection point, the annular wall exhibits a guiding micro-ripple, formed by a regular alternation of troughs and crests extending axially from the upstream to the downstream area. This micro-ripple is specifically designed to channel the boundary layers of the air flowing along the wall, creating a structure that promotes flow adhesion. This helps to limit separation zones and reduce recirculation phenomena, which are generally responsible for energy losses and flow destabilization. By more effectively guiding the airflow, the micro-ripple stabilizes streamlines, improves flow distribution, and helps reduce aerodynamic losses.

[0007] The present invention also provides a simple, effective and economical solution to this need.

[0008] In this document, the term "micro-ripple" refers to repetitive variations in the diameter of the annular wall, which appear as an alternation of crests and troughs. These variations are characterized in terms of amplitude (the height of the crests or the depth of the troughs relative to the midline of the original surface), and wavelength (distance between two successive crests or troughs). For the purposes of this document, this amplitude is preferably between a few millimeters and a few tens of millimeters. As those skilled in the art will understand, the inflection point corresponds to the area where the curvature of the wall changes sign; that is, it marks the transition between a convex and a concave section.

[0009] As the person skilled in the art will understand, the words "trough" and "crest" are used in the sense that the waviness is such that the distance from a trough to the driving axis (in other words, the diameter of the wall at the level of a trough) is strictly less than the distance from a crest to the driving axis (or in other words, the diameter of the wall at the level of a crest).

[0010] As the person skilled in the art will understand, the axial extension of the micro-ripple is substantially parallel to the direction of the main flow of the airflow through the turbomachine.

[0011] The use, in this document, of the verb "comprendre" (to understand), its variants, and its conjugations, cannot in any way exclude the presence of elements other than those mentioned. Similarly, the use, in this document, of the indefinite article "un" (a), "une" (an), or the definite article "le" (the), "la" (the), or "l'" (it) to introduce an element does not exclude the presence of a plurality of these elements.

[0012] In one embodiment, the annular wall comprises a radially internal segment including the micro-corrugation and a radially external segment. The term "radially internal" refers to the position closest to the longitudinal axis of the turbomachine. Conversely, the term "radially external" refers to the position farther from the axis. Advantageously, the radially internal segment of the annular wall, which is provided with the micro-corrugation, is specifically designed for aerodynamic purposes to optimize airflow through the turbomachine. This segment can, in particular, be made of a thermoplastic matrix composite material. This allows the segment to be more malleable in terms of formability for manufacturing.

[0013] Furthermore, the radially external segment of the annular wall can be designed for structural purposes. This segment can typically be smoother and free of micro-ripples, providing a robust surface that can serve as structural support, protecting the radially internal segment of the annular wall. The radially external segment can be made of a different material, suitable for providing high structural strength, such as metallic alloys or composites compatible with the thermal environment. Advantageously, the segmented design of the annular wall allows for optimization between internal aerodynamic needs and external structural requirements. In this configuration, the radially external segment can be annular over 360° or formed from several parts (e.g., 2 x 180°).

[0014] Preferably, the micro-ripple is sinusoidal. Sinusoidal micro-ripples are characterized by regular waves that mimic the mathematical form of a sine function. The peaks and troughs are thus regularly spaced, with constant amplitude and wavelength. Advantageously, the sinusoidal shape is particularly effective at guiding airflow smoothly and continuously, helping to maintain laminar flow. Furthermore, the sinusoidal shape can be easily adjusted (in terms of amplitude and wavelength) to suit various design specifications, providing a flexible solution for airflow management.

[0015] Preferably, the crests of the micro-ripple have a height less than or equal to 1% of the average diameter of the annular wall, and in particular less than or equal to 0.5%. This means that the amplitude of the micro-ripple is very small compared to the overall size of the annular wall. For example, if the average diameter of the annular wall is 1000 mm, the crest height would not exceed 10 mm. Advantageously, by having a minimal crest height, the micro-ripple at the annular wall helps stabilize the airflow by reducing disturbances and aerodynamic noise, while having a minimal impact on the overall structure.

[0016] In one embodiment, the turbomachine further includes a variable-pitch rotor located upstream of the main rotor. This additional rotor, by adjusting the orientation of its blades, can generate flow distortions, particularly in the secondary flow. The invention is therefore particularly well-suited to this turbomachine configuration, as it compensates for variations in airflow and reduces the disturbances caused by these distortions.

[0017] Preferably, the turbomachine also includes a stator for straightening the second flow, the downstream position being within a range between a leading edge and a trailing edge of the stator blades, according to a predefined tolerance. Preferably, this tolerance is on the order of 25% of the distance between the leading and trailing edges of the stator blades. In this particular configuration of the turbomachine, aerodynamics can be further improved. Indeed, when the rotor speed becomes desynchronized with the airflow of the second flow, this can cause excessive pressure on the stator blades. If the pressure becomes too great, that is, if the angle of attack of the air on the stator blades exceeds a certain threshold, the flow over the upper surface of the stator blades stalls, resulting in aerodynamic instability.Advantageously, extending the micro-ripple to the stator level helps stabilize the secondary flow by readjusting its wall direction to its nominal value. This ensures stable performance even under varying flight conditions. Furthermore, with a variable-pitch rotor, variations in the flow's angle of attack are further aggravated, increasing potential instabilities. In this case, the invention allows for optimal management of these variations, thereby reducing the risk of more significant aerodynamic instabilities and improving the system's robustness.

[0018] For example, the downstream position is axially aligned with the trailing edge of the stator blades. Advantageously, this provides sufficient length for efficient airflow guidance through the turbomachine. With sufficient guidance length, the micro-ripple can effectively help smooth the airflow, minimizing turbulence, which occurs particularly when air interacts with the stator blades. This alignment helps to further stabilize the system. the second flow, which is crucial for the thrust and flight performance of the aircraft.

[0019] Preferably, each micro-ripple crest extends axially, following a path along the skeleton line of a stator blade tip profile. This configuration directly influences how the airflow interacts with the stator blades. Advantageously, this allows for an orderly channeling of the airflow, resulting in a smoother transition of the air along the surface of the stator blades. This allows the air to adhere more closely to the blade surface, improving the straightening quality. Preferably, in the upstream region of the stator, each micro-ripple crest extends axially, remaining parallel to a tangent drawn to the leading edge of the skeleton line of the blade tip profile. This means that, just before the air encounters the stator, the crests follow a direction aligned with the natural path of the airflow toward the leading edge of the stator blades.Advantageously, this minimizes sudden disturbances in the airflow, thereby reducing turbulence.

[0020] Alternatively, the tail position is axially aligned with the leading edge of the stator blades within a predefined tolerance. Preferably, this tolerance is approximately 25% of the distance between the leading and trailing edges of the stator blades. For example, the tail position can be exactly aligned with the leading edge. Alternatively, it can be located a short distance from it. In other words, the tail position can approach the leading edge without coinciding with it. In this configuration, the micro-ripple gradually terminates before reaching the leading edge of the stator blades. This can be achieved by a decreasing gradient in the ripple amplitude, transforming an abrupt transition into a smoother one. Advantageously, this facilitates stator assembly at the annular wall, since the wall surface becomes more regular and smooth at the stator.A smoother surface approaching the stator blades also reduces mechanical stresses that can result from a corrugated annular wall during assembly.

[0021] The invention further proposes a method for manufacturing a turbomachine according to any one of the aforementioned embodiments. The method is characterized in that the fabrication of the annular wall includes a composite molding or metal fabrication step. Advantageously, by offering a manufacturing method that includes both composites and metals, the invention ensures maximum flexibility to meet diverse performance and manufacturing requirements. The metal fabrication step may, for example, include an additive manufacturing step (metal 3D printing). This technology allows the fabrication of complex shapes, such as corrugated forms, which are otherwise difficult or impossible to achieve with conventional methods.As for the composite molding stage, this manufacturing method allows the annular wall to be molded into complex shapes without requiring additional machining or finishing steps, thanks to the precision of the molding. Advantageously, composite materials can be formulated to offer an excellent surface finish directly from the mold, eliminating the need for post-fabrication surface treatments.

[0022] Preferably, composite molding includes a step of draping long carbon fibers into a mold with a shape corresponding to the annular wall. The carbon fibers are draped manually or using automated dispensing machines into the mold, following the geometry required for micro-corrugation and the contours of the annular wall. This process requires precision to ensure that the fibers are optimally aligned to maximize the mechanical and aerodynamic properties of the final part. Preferably, the carbon fibers are pre-impregnated and cured in an autoclave or under pressure. Advantageously, carbon fibers offer exceptional strength and stiffness at a low mass, ideal for structural components of turbomachinery where weight is critical.Draping allows the fibers to be conformed to very specific geometries, essential for micro-ripple characteristics and other precise contours.

[0023] Preferably, the construction of the annular wall also includes the following steps: - creation of a radially internal segment including the micro-undulation, - creation of a radially external segment, and - assembly of the segments radially internally and externally.

[0024] Manufacturing techniques for the radially external segment may include machining for metals or draping for composites, depending on specific strength and durability requirements. The materials used and the manufacturing method must ensure that this segment can withstand external stresses, including thermal and mechanical loads. The assembly of two segments can be achieved using methods such as bolting, riveting, or the use of structural adhesives, depending on the nature of the materials involved and the performance requirements. Metal or thermoplastic composite welding or brazing techniques may be considered depending on the materials used.

[0025] Preferably, the production of the radially internal segment includes a thermoplastic injection molding step. Advantageously, injection molding is particularly well-suited for high-volume production due to its speed and ability to produce complex parts with high precision. The efficiency of this method depends on the injection strategy used, the fiber orientation, and the ease of demolding the part. Brief description of the figures

[0026] Other features and advantages of the present invention will become apparent from the detailed description that follows, for understanding of which reference should be made to the accompanying figures, among which: - Figure 1 is a partial schematic axial cross-sectional view of an aircraft turbomachine on which a housing is intended to be arranged according to an embodiment of the invention, - Figure 2 is a partial schematic radial cross-sectional view of an aircraft turbomachine, illustrating a casing comprising an annular wall with a micro-corrugation, - Figure 3 is a partial schematic axial cross-sectional view of an aircraft turbomachine, illustrating a casing comprising an annular wall formed of a radially internal segment and a radially external segment.

[0027] The drawings in the figures are not to scale. Similar features are generally denoted by similar reference numerals in the figures. Within the scope of this document, identical or analogous features may bear the same reference numerals. Furthermore, the presence of reference numerals or letters in the drawings shall not be considered limiting, even when such numerals or letters are specified in the claims. Detailed description of certain embodiments of the invention

[0028] This section provides a detailed description of certain embodiments of the present invention. The invention is described with specific embodiments and references to figures, but the invention is not limited by them. In particular, the drawings and figures described below are schematic only and are not limiting.

[0029] Figure 1 is a partial schematic axial cross-sectional view of an aircraft turbomachine 20. As shown in Figure 1, the turbomachine 20 is, for example, a dual-flow turbomachine (but it can also have more than two flows). It has a main flow direction extending along a longitudinal X-axis and creates two separate airflows from a main flow 2 admitted at the inlet of said turbomachine 20.

[0030] The main flow 2 is first compressed by a rotor 6, for example, in the shape of a fan. At the outlet of this rotor 6, the main flow 2 is then separated into two distinct flows: a first flow forming a primary flow 4 which circulates in a primary channel 90 of a turbomachine engine 20, and a second flow forming a secondary flow 3 which circulates in a secondary vein 80 of the turbomachine 20.

[0031] The separation of the primary flow 4 and the secondary flow 3 is ensured by a separation nozzle 7 which is located downstream of the blower. The separation nozzle 7 comprises a leading edge 71, a first annular face 73 forming an inner wall of the primary flow 90, and a second face 72 forming an inner wall of the secondary flow 80.

[0032] Subsequently, the primary stream 4 is compressed by a low-pressure compressor 8 and a high-pressure compressor 10, and then is burned with fuel in a combustion chamber of the turbomachine engine 20.

[0033] The secondary flow 3 is directed towards stator blades 5 located in the secondary channel 80 in order to straighten the secondary flow 3 with respect to the X-axis of the turbomachine 20. The stator blades 5 have a leading edge 51, a trailing edge 52, and a tip 53 extending between the leading edge 51 and the trailing edge 52. The turbomachine 20 according to the invention may have more than two flows, where the secondary flow 3 and the secondary channel 80 can be considered as an intermediate flow and an intermediate channel. This turbomachine 20 may also have one or more rotors located upstream of the rotor 6, for example, a row of variable-pitch blades, shrouded or unshrouded.

[0034] The turbomachine 20 further includes a casing comprising an annular wall 1 arranged, preferably, to enclose the blade ends of the blower and stator 5.

[0035] The annular wall 1 has an inflection point 19 which is substantially aligned with the leading edge 71 of the separating nozzle 7. This inflection point 19 makes it possible to maintain an adequate cross-section for the passage of air, compensating for the physical obstruction created by the separating nozzle 7. Advantageously, the inflection point 19 facilitates a smoother transition between the main flow 2 and the secondary flow 3. The annular wall 1 comprises a micro-undulation, formed by alternating ridges and troughs. Each ridge and trough extends axially from the inflection point 19 of the annular wall 1 to a downstream position. Preferably, this position is within an interval between the leading edge 51 and the trailing edge 52 of the stator blades 5. Preferably, each crest of the micro-ripple extends axially along a path of a skeleton line of a head profile 53 of a stator blade 5.

[0036] Figure 2 is a partial schematic radial cross-sectional view of the turbomachine 20 of Figure 1. The radial section AA is located downstream of the inflection point 19 of the annular wall 1.

[0037] As shown in Figure 2, the annular wall 1 of the turbomachine housing 20 encloses the blade tips of the stator 5. This annular wall 1 has a micro-ripple, formed by alternating crests 40 and troughs 60. The crests 40 of the micro-ripple are the highest areas of the surface of the annular wall 1, where the diameter is at its maximum. Conversely, the troughs 60 are the lowest depressions of the surface of the annular wall 1, where the diameter is at its minimum. Preferably, the micro-ripple has a sinusoidal shape, although other geometric shapes can be adopted, such as trapezoidal, triangular (sawtooth), etc.

[0038] The annular wall 1 is characterized by a mean diameter 11, around which the entire micro-corrugation design is constructed. The crests 40 of the micro-corrugation, which alternate with troughs 60 to form, preferably, a sinusoidal surface, are preferably particularly limited in size so as not to compromise the structural integrity or the aerodynamic efficiency of the turbomachine 20. Preferably, the height 12 of these crests 40 is designed not to exceed 1% of the mean diameter 11 of the annular wall 1.

[0039] Preferably, each ridge 40 is aligned so as to coincide precisely with a leading edge 51 of a stator blade 5. The circumferential alignment of the ridges 40 of the micro-ripple with the leading edges 51 of the stator blades 5 creates a preferential path for the air flowing towards the stator 5. This helps to guide the airflow more smoothly around the stator blades, thus reducing the disturbances and turbulence that might otherwise occur. if the 40 peaks were positioned randomly or misaligned with respect to the stator blades.

[0040] At the level of the separation nozzle 7, Figure 2 shows, for example, that it comprises an inner face 73 and an outer face 72 which define a space where attachment points 9 for a row of blades of the low-pressure compressor 8 are housed. These blades are stator-type straightening blades which can be fixed or have variable pitch. The variable pitch of these blades allows the blade angle to be dynamically adjusted according to the flight conditions and load of the turbomachine 20, thus optimizing engine performance by regulating the airflow through the low-pressure compressor 8.

[0041] Figure 3 is a partial schematic axial cross-sectional view of an aircraft turbomachine 20 on which the housing comprising the annular wall 1 is intended to be arranged. The annular wall 1 is, for example, arranged to enclose the blade tips of the rotor 6 and stator 5. The annular wall 1 is, for example, formed of a radially internal segment 101 comprising the micro-corrugation and a radially external segment 100. Thus, the micro-corrugation at the radially internal segment 101 helps to regulate the airflow behavior, reducing turbulence and stabilizing the secondary airflow 3 interacting with the stator 5 blades. The radially internal segment 101 thus forms the aerodynamic interface of the annular wall 1. As shown in Figure 3, the micro-ripple, formed by an alternation of troughs 60 and crests 40, extends, for example, to a downstream position, intended to be aligned with a leading edge 51 of stator blades 5.Preferably, the micro-ripple is designed to terminate gradually before reaching the leading edge 51 of the stator 5 blades. This allows for a smooth surface of the annular wall 1 at the stator 5, which facilitates assembly and simplifies the fixing of the blades at the annular wall 1.

[0042] Preferably, the radially external segment 100 is designed to provide a robust support structure. Preferably, the radially external segment 100 includes an axisymmetric housing configured to receive the radially internal segment 101. This housing ensures a secure connection and structurally integrated between the two segments. The assembly between the two segments is thus carried out in such a way as to optimize the continuity of the internal surface of the annular wall 1. The radially external segment 100 can be formed of a metallic material or of a composite material obtained by draping.

[0043] The radially internal segment 101 is preferably made from a thermoplastic matrix composite material. This choice of material is motivated by several factors, including its fatigue resistance, its lightness, and its ability to be precisely formed with micro-corrugation.

[0044] The combination of materials between the radially internal segment 101 and the radially external segment 100 is designed to offer a harmony between flexibility and rigidity, allowing the annular wall 1 to withstand various thermal and mechanical stresses without compromising aerodynamic performance.

[0045] In a specific configuration of the radially internal segment 101, it can itself be manufactured in several separate parts. This allows for simpler production and modular installation. To maintain effective continuity and sealing between the parts, silicone seals can be used. Advantageously, silicone is chosen for its excellent elasticity, heat resistance, and its ability to form durable, watertight joints. Furthermore, the silicone seals ensure that the internal surface of the radially internal segment 101 remains smooth and continuous, which is particularly useful for maintaining aerodynamic performance by reducing airflow disturbances caused by the joints between the segment parts.

[0046] In summary, the invention relates to an aircraft turbomachine 20 comprising a casing designed to improve aerodynamics and airflow management. The casing includes an annular wall 1 with a guiding micro-corrugation, formed by alternating troughs 60 and crests 40. The micro-corrugation reduces turbulence and the pumping effect, thereby stabilizing the airflow and improving the overall efficiency of the turbomachine 20.

Claims

Demands 1. Aircraft turbomachine (20), comprising: - a rotor (6) to generate a main flow (2), - a separating nozzle (7) to form a separation between a first stream (4) and a second stream (3), originating from the main stream (2), and - a housing comprising an annular wall (1), said annular wall (1) comprising a guiding micro-corrugation, formed of an alternation of hollows (60) and crests (40), each crest (40) and each hollow (60) extending axially from an upstream position to a downstream position, said upstream position coinciding with an inflection point (19) of the annular wall (1), according to a predefined tolerance, said inflection point (19) being axially aligned with a leading edge (71) of said separating nozzle (7), according to a predefined tolerance.

2. Turbomachine (20) according to the preceding claim, characterized in that the annular wall (1) comprises a radially internal segment (101) comprising the micro-corrugation and a radially external segment (100).

3. Turbomachine (20) according to any one of the preceding claims, characterized in that the micro-ripple is sinusoidal.

4. Turbomachine (20) according to any one of the preceding claims, characterized in that the crests (40) of the micro-ripple have a height less than or equal to 1% with respect to an average diameter (11) of the annular wall (1).

5. Turbomachine (20) according to any one of the preceding claims, further comprising a stator (5) for straightening the second flow (3), said downstream position being contained within an interval between a leading edge (51) and a trailing edge (52) of blades of said stator (5), according to a predefined tolerance.

6. Turbomachine (20) according to the preceding claim, characterized in that said downstream position is axially aligned with the trailing edge (52) of stator blades (5).

7. Turbomachine (20) according to the preceding claim, characterized in that each crest (40) of the micro-ripple extends axially, following a trajectory of a skeleton line of a head profile (53) of a stator blade (5).

8. Turbomachine (20) according to claim 5, characterized in that said downstream position is axially aligned with the leading edge (51) of stator blades (5), according to a predefined tolerance.

9. Turbomachine (20) according to any one of the preceding claims, further comprising a variable-pitch rotor located upstream of said rotor (6).

10. Method of manufacturing a turbomachine (20) according to any one of the preceding claims, characterized in that the production of the annular wall (1) includes a composite molding or metal fabrication step.

1. A manufacturing method according to the preceding claim, characterized in that the composite molding comprises a fiber draping step. 16 long carbon pieces in a mold comprising a shape corresponding to the annular wall (1).

12. Manufacturing method according to claim 10, characterized in that the production of the annular wall (1) further comprises the following steps: - realization of a radially internal segment (101) including the micro-undulation, - creation of a radially external segment (100), and - assembly of segments (100,101) radially internal and external.

13. Manufacturing method according to the preceding claim, characterized in that the production of the radially internal segment (101) includes a thermoplastic injection molding step.

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