Inlet for a nacelle of an aircraft propulsion assembly for facilitating a thrust phase and a reverse thrust phase and method of use thereof

Abstract

The inlet lip (13) of the nacelle (2) of an aircraft propulsion assembly (8) comprises an inner wall (11) and an outer wall (12) connected upstream by an inlet lip (13) comprising thick portions and thin portions (17) alternately distributed on the circumference of the inlet lip (13), each thick portion comprising an upstream leading edge for separating, in thrust phase, an upstream flow (F) into an outer flow (F-EXT) guided by the outer wall (12) and an inner flow (F-INT) guided by the inner wall (11), each thin portion (17) comprising a downstream leading edge (18) located longitudinally downstream of each upstream leading edge so as to separate, in thrust reversal phase (B), a reversal flow (F-INV) at the inlet lip (13).

Description

Technical Field

[0001] This invention relates to the field of aircraft propulsion components, and more specifically, to the nacelle air intake of an aircraft propulsion component.

[0002] Referring to Figure 1A, as is known, an aircraft propulsion assembly 800 extends along a longitudinal axis X from upstream to downstream, and includes a turbine engine 700 and a nacelle 200. The turbine engine 700 extends along the longitudinal axis X and is configured to propel the aircraft by accelerating the internal airflow F-INT circulating from upstream to downstream within the turbine engine 700. Conversely, the nacelle 200 extends outwardly around the turbine engine 700 along the longitudinal axis X, thereby guiding the internal airflow F-INT within the turbine engine 700. Hereinafter, the terms "upstream" and "downstream" refer to directions relative to the longitudinal axis X, while the terms "internal" and "external" refer to radial directions relative to the longitudinal axis X.

[0003] As shown in Figure 1A, the turbine engine 700 is a bypass turbine engine, with an upstream fan 300 rotatably mounted about a longitudinal axis X for accelerating the flow of internal airflow F-INT from upstream to downstream. Downstream of the fan 300, the turbine engine 700 also includes a radially inward main airflow passage 400 and a radially outward secondary airflow passage 500, which are separated by a housing 600. The housing 600 is configured to guide a first portion of the internal airflow F-INT (referred to as the main airflow F1) into the main airflow passage 400 for fuel combustion, and to guide a second portion of the internal airflow F-INT (referred to as the secondary airflow F2) into the secondary airflow passage 500 to generate thrust for the turbine engine 700.

[0004] Following a known method, referring again to Figure 1A, the nacelle 200 extends radially outward to the fan 300 and defines a secondary airflow passage 500 radially outward. The nacelle 200 includes an air inlet 100 extending circumferentially around a longitudinal axis X at its upstream end. The air inlet 100 includes an inner wall 110 facing the longitudinal axis X and an outer wall 120 opposite to the inner wall 110, the inner wall 110 and the outer wall 120 being connected together by an air inlet lip 130. As shown in Figure 1A, the radial section of the air inlet lip 130 has an aerodynamic circular profile, which can separate the upstream airflow F into an internal airflow F-INT guided by the inner wall 110 and an external airflow F-EXT guided by the outer wall 120. The air inlet lip includes a leading edge 140, which is defined on each radial section by a point located at the upstreammost point of the air inlet lip 130, all of which form a closed curve around the longitudinal axis X.

[0005] Referring to Figure 1B, to reduce the aircraft's braking distance (especially during landing), it is known that the airflow direction in the secondary airflow passage 500 can be altered to perform a reverse thrust phase B. Hereinafter, a distinction is made between thrust phase A (Figure 1A) and reverse thrust phase B (Figure 1B). In thrust phase A, the secondary airflow F2 circulates from upstream to downstream in the secondary airflow passage 500, while in reverse thrust phase B, the reverse airflow F-INV circulates from downstream to upstream. It should be clarified that during reverse thrust phase B, the internal airflow F-INT from the upstream airflow F circulates from upstream to downstream at the base of the fan 300 to supply the main airflow F1 (similar to thrust phase A). The main airflow F1 can also be supplied by a portion of the reverse airflow F-INV that bypasses the casing 600.

[0006] To execute the reverse thrust phase, it is known that the secondary airflow passage 500 downstream of the fan 300 must be at least partially blocked, and the grid in the nacelle 200 must be opened together to form a reverse airflow F-INV opposite to the direction of the secondary airflow F2. However, a disadvantage of this thrust reversal system is that it increases the mass of the aircraft propulsion assembly 800, especially for the large-diameter nacelle 200 used in high-dilution-rate aircraft propulsion assemblies, which are defined as aircraft propulsion assemblies where the ratio of the mass of the secondary airflow F2 to the mass of the primary airflow F1 is greater than 16.

[0007] Referring to Figure 1B, for high dilution ratio aircraft propulsion assemblies, it is known to provide a variable pitch fan 300 (abbreviated as "VPF") that includes blades with controllable pitch angles to reverse the circulation direction of airflow in the secondary airflow passage 500. Specifically, during the reverse thrust phase B, the reverse airflow F-INV circulates from downstream to upstream in the secondary airflow passage 500, then passes through the fan 300 and is guided upstream by the inner wall 110 of the inlet 100. The reverse airflow F-INV (particularly radially outward near the nacelle 200) then moves in the opposite direction to the upstream airflow F, thus achieving braking. The reverse airflow F-INV then merges with the external airflow F-EXT and enters the secondary airflow passage 500 through the downstream end of the nacelle 200.

[0008] In fact, it has been observed that when the reverse airflow F-INV merges with the external airflow F-EXT, the reverse airflow F-INV remains attached to the inlet 100; that is, it moves along the contour of the inlet 100 without detaching from the inner wall 110 and the outer wall 120. This phenomenon is known as the "Coanda effect." This phenomenon often accelerates the reverse airflow F-INV at the inlet 100, thereby generating a local low-pressure DP, resulting in a force opposite to the thrust. This phenomenon may reduce the performance of the turbine engine 700 during the reverse thrust phase, which is undesirable.

[0009] To improve the performance of the turbine engine 700 during the reverse thrust phase, patent applications FR1904087A1 and FR1904094A1 disclose the movable mounting of deflectors and rectifier blades on the inlet 100, which deploy during the reverse thrust phase B and retract during the thrust phase A. Alternatively, patent applications FR1904089A1 and FR1904096A1 teach the movable or elastically deformable portion of the inlet 100 during the reverse thrust phase B. Patent application FR1904092A1 also teaches the formation of an internal duct within the inlet that opens during the reverse thrust phase B to divert a portion of the reverse airflow F-INV. The advantage of all these solutions is that the circular profile of the inlet can only be changed during the reverse thrust phase B to prevent the formation of localized low-pressure DP, without performance degradation during the thrust phase A. However, the disadvantage of these solutions is the need for a dual-profile inlet structure, which is complex, costly, and requires actuation, making it susceptible to failure.

[0010] Incidentally, the nozzles and nacelle air outlets known in patent application US20190128214A1 include a wedge shape, which can locally generate air vortices during the reverse thrust phase to facilitate air intake at the air outlet. Such outlets and nozzles cannot produce the Coanda effect at the air intake.

[0011] Therefore, the present invention aims to provide a nacelle air inlet for an aircraft propulsion assembly that can improve the performance of a turbine engine during both the thrust and reverse thrust phases, and has a simple and robust structure. Summary of the Invention

[0012] This invention relates to an air inlet for a nacelle of an aircraft propulsion assembly extending downstream along a longitudinal axis, the aircraft propulsion assembly including a turbine engine including a radially inner main airflow passage and a radially outer secondary airflow passage, the main airflow passage and the secondary airflow passage being configured to guide the main airflow and secondary airflow respectively from upstream to downstream during the thrust phase, the turbine engine including a fan rotatably mounted about the longitudinal axis at its upstream end, the aircraft propulsion assembly including a thrust reversing device configured to change the secondary airflow into a reverse airflow circulating from downstream to upstream in the secondary airflow passage during the reverse thrust phase, the nacelle extending outward around the turbine engine, including an air inlet at the upstream end of the nacelle, the air inlet extending circumferentially about the longitudinal axis, and the air inlet including an inner wall facing the longitudinal axis and an outer wall opposite to the inner wall, the two being connected upstream by an air inlet lip.

[0013] The present invention is characterized by: The intake lip includes a thickness defined radially relative to the longitudinal axis, and comprises multiple thick portions and multiple thin portions alternately distributed on the circumference of the intake lip. Each thick section includes an upstream leading edge configured to separate the upstream airflow circulating from upstream to downstream into an external airflow guided by the outer wall and an internal airflow guided by the inner wall, to facilitate the thrust phase. Each thin section includes a downstream leading edge located longitudinally downstream of each upstream leading edge and configured to separate the reverse airflow at the inlet lip to facilitate the reverse thrust phase.

[0014] Thanks to this invention, the air inlet comprises a fixed structure with two different profiles, enabling improved performance in both the thrust and reverse thrust phases with a simple, convenient, and economical solution. More specifically, the air inlet comprises a thick profile upstream and a thin profile downstream. The thick profile is first encountered by the upstream airflow circulating from upstream to downstream, while the thin profile is first encountered by the reverse airflow circulating from downstream to upstream. The thick profile facilitates the separation of the upstream airflow into internal and external airflows, which circulate inside and outside the nacelle, respectively, thereby promoting airflow during the thrust phase. The thin profile allows the reverse airflow to be separated from the inlet lip, preventing the Coanda effect and thus improving performance during thrust reversal. The thick portion forming the thick profile is preferably distributed across the entire circumference of the inlet lip to provide a comprehensive effect on the upstream airflow. Similarly, the thin portion forming the thin profile is preferably distributed across the entire circumference of the inlet lip to provide a comprehensive effect on the reverse airflow. The advantages of the non-movable inlet lip structure are longer service life and simpler maintenance.

[0015] According to one aspect of the invention, the inlet lip includes a plurality of boundary portions extending between each thick portion and each thin portion, each boundary portion including a boundary leading edge to separate reverse airflow during swirling, thereby facilitating the reverse thrust phase. Preferably, each boundary portion extends longitudinally between adjacent upstream and downstream leading edges. The advantage of such boundary portions is that they provide continuity between the thick and thin portions, thus maintaining the aerodynamic performance of the inlet. In addition to the thin portions, these boundary portions also enable the separation of reverse airflow, especially during airflow swirling.

[0016] According to one aspect of the invention, each boundary leading edge extends along a separation axis forming an angle of 35° to 70° with the longitudinal axis in a plane tangent to the inlet lip. In practice, the reverse airflow includes swirling air generated as it passes through the fan, thus its flow direction forms an angle of 30° to 45° with the longitudinal axis. Advantageously, the separation axis forms an angle between 80° and 100° with the flow direction of the reverse airflow. The reverse airflow preferably arrives substantially perpendicular to the boundary leading edge.

[0017] According to one aspect of the present invention, the intake lip includes a wavy leading edge, preferably composed of a plurality of wedge shapes. The leading edge is composed of an upstream leading edge, a junction leading edge, and a downstream leading edge, thus having an aerodynamic geometry and two longitudinally separated profiles.

[0018] According to a preferred aspect of the present invention, the upstream leading edge of each thick portion includes a curved shape. According to a preferred aspect of the present invention, the downstream leading edge of each thin portion includes a curved shape. This can improve the aerodynamic performance and make its shape more reasonable, thus having a more comprehensive impact on the air flow.

[0019] According to one aspect of the present invention, the upstream leading edge of each thick portion includes a convex profile that extends circumferentially relative to the longitudinal axis and bulges upstream. According to one aspect of the present invention, the downstream leading edge of each thin portion includes a concave profile that extends circumferentially relative to the longitudinal axis and depresses upstream. In other words, each thick portion points upstream and each thin portion points downstream. Preferably, the upstream leading edge of each thick portion includes a convex surface opposite to the concave surface of the downstream leading edge of each thin portion. This can make the distribution of the upstream leading edge and the downstream leading edge basically uniform.

[0020] The upstream leading edges preferably each include an upstream point, and all upstream points are horizontally aligned relative to the longitudinal axis. Preferably, all upstream points belong to an upstream circle, and the longitudinal axis passes through the center of the upstream circle. The downstream leading edges preferably each include an upstream point, and all upstream points are horizontally aligned relative to the longitudinal axis. Preferably, all upstream points belong to a downstream circle, and the longitudinal axis passes through the center of the upstream circle. Thus, the upstream leading edges can act together on the upstream air flow, and the downstream leading edges can act together on the reverse air flow, thereby improving the efficiency.

[0021] According to one aspect of the present invention, the intake lip includes a housing: · In each radial plane of the thick portion, the housing is defined by the radius of curvature (R) of the upstream leading edge, · In each radial plane of the thin portion, the housing is defined by the radius of curvature (r) of the downstream leading edge, · The radius of curvature conforms to the following relationship: R > 1.5*r, preferably: R < 3*r.

[0022] The radius of curvature preferably conforms to the following relationship: 1.8*r < R < 2.2*r. This can have a sufficiently thick leading edge and a sufficiently thin leading edge, while also limiting the mass and providing a robust intake. The junction portion also includes an aerodynamic shape that can provide a gradual transition between the two profiles.

[0023] Each junction portion is preferably defined in the radial plane by the radius of curvature R of the junction leading edge * which should conform to the following relationship: r < R *<R。

[0024] According to one aspect of the invention, on at least one transverse plane located downstream of the downstream leading edge, the radial thickness of each thick portion is greater than the radial thickness of each thin portion. This allows the internal airflow to be directed downstream of the upstream leading edge during the thrust phase. The thick portions define a priority circulation path for internal airflow within the nacelle, while the thin portions define a priority circulation path for reverse airflow.

[0025] Preferably, each thick portion extends and protrudes inward toward the air intake, so as not to change the external shape of the air intake lip and to maintain its aerodynamic performance.

[0026] The present invention also relates to the assembly of the air intake and fan as described above, wherein the fan preferably constitutes a thrust reversing device. Fans with variable-pitch blades are particularly well-suited for high-dilution aircraft propulsion systems, i.e., where the ratio of secondary airflow mass to primary airflow mass is greater than 16.

[0027] The present invention also relates to a nacelle for an aircraft propulsion assembly extending along a longitudinal axis from upstream to downstream and including a turbine engine. The turbine engine includes a radially inner main airflow passage and a radially outer secondary airflow passage, the main airflow passage and the secondary airflow passage being configured to guide the main airflow and the secondary airflow respectively from upstream to downstream during the thrust phase. The turbine engine includes a fan rotatably mounted about the longitudinal axis at its upstream end. The aircraft propulsion assembly includes a thrust reversing device configured to change the secondary airflow into a reverse airflow circulating from downstream to upstream in the secondary airflow passage during the reverse thrust phase. The nacelle extends outward around the turbine engine and includes an air inlet as described above at its upstream end.

[0028] The present invention also relates to an aircraft propulsion assembly extending downstream along a longitudinal axis, the assembly including a turbine engine including a radially inner main airflow passage and a radially outer secondary airflow passage, the main airflow passage and the secondary airflow passage being configured to guide the main airflow and the secondary airflow from upstream to downstream, respectively, during the thrust phase, the turbine engine including a fan rotatably mounted about the longitudinal axis at its upstream end, the aircraft propulsion assembly including a thrust reversing device configured to change the secondary airflow into a reverse airflow circulating from downstream to upstream in the secondary airflow passage during the reverse thrust phase, the aircraft propulsion assembly including a nacelle extending outward around the turbine engine, the upstream end of the nacelle including an air inlet as described above, the fan preferably being configured as a thrust reversing device.

[0029] The present invention also relates to a method of using an air inlet for an aircraft propulsion assembly nacelle as described above, wherein: • During the thrust phase, each thick section of the inlet lip separates the upstream airflow circulating from upstream to downstream into an external airflow guided by the outer wall and an internal airflow guided by the inner wall, as well as... • During the reverse thrust phase, each thin section of the intake lip separates a reverse airflow that circulates from downstream to upstream at the intake lip.

[0030] Advantageously, this method requires no steps to move and / or deform the air intake, which maintains its shape during the reverse thrust phase, resulting in a simple, robust, durable, and economical structure. This method is also easy to implement quickly, allowing for seamless transitions from one stage to another.

[0031] The present invention also relates to a method of using an aircraft propulsion assembly as described above, wherein: • During the thrust phase, each thick section of the inlet lip separates the upstream airflow circulating from upstream to downstream into an external airflow guided by the outer wall and an internal airflow guided by the inner wall, as well as... • During the reverse thrust phase, the reverse thrust device is activated, and each thin section of the intake lip separates the reverse airflow circulating from downstream to upstream at the intake lip.

[0032] During the reverse thrust phase, it is preferable to change the pitch of the fan blades to create a reverse airflow. Attached Figure Description

[0033] A better understanding of the invention will be achieved by reading the following description as an example and referring to the following figures as a non-limiting example, wherein similar objects are referred to in exactly the same way.

[0034] Figure 1A is a longitudinal half-section schematic diagram of an aircraft propulsion component in the thrust phase in the prior art.

[0035] Figure 1B is a longitudinal half-section schematic diagram of the aircraft propulsion assembly in Figure 1A during the reverse thrust phase.

[0036] Figure 2A is a longitudinal half-sectional schematic diagram of an aircraft propulsion assembly in the thrust phase according to an embodiment of the present invention.

[0037] Figure 2B is a longitudinal half-section schematic diagram of the aircraft propulsion assembly in the reverse thrust phase of Figure 2A.

[0038] Figure 3 is a perspective view of the air intake of the aircraft propulsion assembly shown in Figures 2A and 2B.

[0039] Figure 4 is a longitudinal view of the air inlet in Figure 3.

[0040] Figure 5 is a schematic diagram of three cross-sections of the air inlet according to Figure 3.

[0041] Figure 6 is a close-perspective view of the air intake in Figure 3.

[0042] Figure 7 is a schematic diagram of the radial cross-section of the junction, thin part and thick part of the air inlet in Figure 3.

[0043] Figure 8A is a schematic diagram of three cross-sections of the air inlet according to another embodiment of the present invention.

[0044] Figures 8B, 8C, and 8D are longitudinal close-up schematic diagrams of the air inlets of three alternative embodiments of the present invention.

[0045] Please note that these illustrations describe in detail what is used to implement the invention; of course, where appropriate, these illustrations can be used to better define the invention. Detailed Implementation

[0046] Referring to Figures 2A and 2B, the present invention relates to an aircraft propulsion assembly 8, which has an innovative aerodynamic profile, particularly at the air intake 1, to improve performance in both the thrust phase A and the reverse thrust phase B.

[0047] As shown in Figure 2A and as described above, the aircraft propulsion assembly 8 extends along a longitudinal axis X from upstream to downstream and consists of a turbine engine 7 and a nacelle 2. The turbine engine 7 extends along the longitudinal axis X and is configured to propel the aircraft by accelerating the internal airflow F-INT circulating from upstream to downstream within the turbine engine 7. The nacelle 2 extends outward around the turbine engine 7 along the longitudinal axis X, thereby guiding the airflow F-INT within the turbine engine 7. Hereafter, the terms "upstream" and "downstream" refer to directions relative to the longitudinal axis X, while the terms "internal" and "external" refer to radial directions relative to the longitudinal axis X.

[0048] As shown in Figure 2A and as described above, the turbine engine 7 is a bypass type, with an upstream fan 3 rotatably mounted about the longitudinal axis X to accelerate the internal airflow F-INT from upstream to downstream. Downstream of the fan 3, the turbine engine 7 also includes a radially inward main airflow passage 4 and a radially outward secondary airflow passage 5, which are separated by a housing 6. The housing 6 is configured to guide a first portion of the internal airflow F-INT (referred to as the main airflow F1) into the main airflow passage 4 for fuel combustion, and to guide a second portion of the internal airflow F-INT (referred to as the secondary airflow F2) into the secondary airflow passage 5, thereby generating the thrust of the turbine engine 7.

[0049] Referring again to Figure 2A, and as previously described, the nacelle 2 extends radially outward to the fan 3 and defines a secondary airflow passage 5 radially outward. At the upstream end, the nacelle 2 includes an air inlet 1 extending circumferentially around the longitudinal axis X. The air inlet 1 includes an inner wall 11 facing the longitudinal axis X and an outer wall 12 opposite to the inner wall 11, the inner wall 11 and the outer wall 12 being connected together by an air inlet lip 13. As shown in Figure 2A, the air inlet lip 13 can separate the upstream airflow F into an internal airflow F-INT guided by the inner wall 11 and an external airflow F-EXT guided by the outer wall 12. The air inlet lip 13 includes a leading edge 14, which is defined in each radial cross-section by a point located at the upstream end of the air inlet lip 13, all points forming a closed curve around the longitudinal axis X.

[0050] Referring to Figure 2B, and as previously described, fan 3 is of the variable pitch type, abbreviated as "VPF," meaning it includes blades with controllable pitch angles to reverse the circulation direction of the airflow in secondary airflow channel 5. In the following text, a distinction will be made between thrust phase A (Figure 2A) and reverse thrust phase B (Figure 2B). Thrust phase A involves the secondary airflow F2 circulating from upstream to downstream in secondary airflow channel 5, while reverse thrust phase B involves the reverse airflow F-INV circulating from downstream to upstream to reduce the aircraft's braking distance (especially during landing). In reverse thrust phase B, the reverse airflow F-INV circulates from downstream to upstream in secondary airflow channel 5, then passes through fan 3 and is guided upstream by the inner wall 11 of inlet 1. The reverse airflow F-INV then flows in the opposite direction to the upstream airflow F, particularly radially outward near nacelle 2, thus achieving braking. The reverse airflow F-INV then merges with the external airflow F-EXT, which enters secondary airflow channel 5 through the downstream end of nacelle 2. It should be noted that during the reverse thrust phase B, the internal airflow F-INT from the upstream airflow F flows from upstream to downstream at the base of the fan 3 to supply the main airflow F1 (similar to thrust phase A). The main airflow F1 can also be provided by a portion of the reverse airflow F-INV that bypasses the housing 6.

[0051] In addition to the variable-pitch fan 3, other thrust reversers can be used. Specifically, it can at least partially block the secondary airflow passage 5 downstream of fan 3 and, together, open the grid in the nacelle 2, thereby creating a reverse airflow F-INV. In particular, grid or flap reversers can be used. The variable-pitch fan 3 is especially suitable for aircraft propulsion components 8 with high dilution ratios, i.e., a mass ratio of secondary airflow F2 to primary airflow F1 greater than 16, as this optimizes onboard mass.

[0052] To improve the performance of the aircraft propulsion assembly 8 during the thrust phase A and the reverse thrust phase B, according to the present invention and referring to FIGS. 2A, 2B and 3, the inlet lip 13 includes thick portions 15 and thin portions 17 that are alternately distributed on the circumference of the inlet lip 13. It should be noted that the thickness of the inlet lip 13 is determined here and then determined radially with respect to the longitudinal axis X.

[0053] Still according to the present invention and referring to FIGS. 2A and 3, each thick portion 15 includes an upstream leading edge 16, which is configured to separate the upstream airflow F into an external airflow F-EXT guided by the outer wall 12 and an internal airflow F-INT guided by the inner wall 11, thereby promoting the thrust phase A. Referring to FIGS. 2B and 3, each thin portion 17 includes a downstream leading edge 18, which is longitudinally downstream of each upstream leading edge 16, and the downstream leading edge 18 is configured to generate a separation zone ZD of the reverse airflow F-INV at the inlet lip 13 to promote the reverse thrust phase B.

[0054] Preferably, as shown in FIG. 3, the inlet lip 13 further includes a junction portion 19 that extends between each thick portion 15 and each thin portion 17. Each junction portion 19 includes a junction leading edge 20, which is configured to separate the reverse airflow F-INV in a complementary manner to the thin portion 17, thereby promoting the reverse thrust phase B.

[0055] In the example of FIG. 3, the inlet lip 13 further includes a fixed structure, without moving and / or deformable components, which is applicable to the thrust phase A and the reverse thrust phase B. More specifically, the inlet lip 13 includes an upstream profile and a downstream profile that are configured to improve performance during the thrust phase A and the reverse thrust phase B, respectively. The upstream airflow F first encounters the upstream profile, i.e., the thick portion 15, while the reverse airflow F-INV first encounters the downstream profile, i.e., the thin portion 17. Therefore, the upstream airflow F and the reverse airflow F-INV are mainly guided by the thick portion 15 and the thin portion 17, respectively.

[0056] As shown in FIG. 3, the arrangement of the thick portion 15, the thin portion 17 and the junction portion 19 is as follows: the thick portion 15, the junction portion 19, the thin portion 17 and the junction portion 19 together form a basic pattern, which repeats on the entire circumference of the inlet 1, and repeats eight times in this example. The number of thick portions 15 and thin portions 17 is equal to equally promote the thrust phase A and the reverse thrust phase B. The number of junction portions 19 is twice that of the thick portions 15 and thus also twice that of the thin portions 17. Preferably, denoting n as the number of thick portions 15 and N as the number of blades of the fan 3, for acoustic reasons, the number n of thick portions 15 satisfies the following relationship: 0.5*N < n < 2*N, where n ≠ N. In the example of FIG. 3, the number n of thick portions 15 is equal to 8.

[0057] In the example of Figure 4, all the thick portions 15 have the same shape and size to facilitate the uniform intake of internal airflow F-INT across the entire circumference of the inlet 1. Similarly, all the thin portions 17 have the same shape and size to facilitate the uniform separation of reverse airflow F-INV across the entire circumference of the inlet 1. In this example, the thick portions 15 and thin portions 17 extend to equal circumferential lengths to equally facilitate thrust phase A and reverse thrust phase B. It goes without saying that at least a portion of the thick portions 15 and / or thin portions 17 may have different shapes and / or sizes.

[0058] Referring to Figure 4, the upstream leading edge 16 of each thick portion 15 includes a convex arcuate profile that protrudes upstream. Conversely, the downstream leading edge 18 of each thin portion 17 includes a concave arcuate profile that recesses upstream. It should be noted that, in each radial section of the thick portion 15, the upstream leading edge 16 of the intake lip 13 is defined by the upstream point of the intake lip 13. Similarly, in each radial section of the thin portion 17, the downstream leading edge 18 of the thin portion 17 is defined by the upstream point of the intake lip 13. This arcuate design of the upstream and downstream leading edges 16 and 18 contributes to improved aerodynamic performance and facilitates their connection, resulting in a simple and continuous intake lip 13. Preferably, the upstream leading edge 16 has a profile opposite to that of the downstream leading edge 18 along an axis laterally symmetrical with respect to the longitudinal axis X.

[0059] As shown in Figures 4 and 5, each upstream leading edge 16 includes an upstream point P16, defined as the most upstream upstream leading edge point 16. In the examples of Figures 4 and 5, the upstream point P16 of the upstream leading edge 16 is aligned with respect to the longitudinal axis X on the transverse plane PT1, preferably belonging to the same circle C1 located on the transverse plane PT1 with the longitudinal axis X passing through its center (Figure 5). Similarly, each downstream leading edge 18 includes an upstream point P18, defined as the most upstream downstream leading edge point 18. In the examples of Figures 4 and 5, the upstream point P18 of the downstream leading edge 18 is aligned in the transverse plane PT2 located downstream of the transverse plane PT1, and preferably belonging to the same circle C2 located on the transverse plane PT2 with the longitudinal axis X at its center (Figure 5). Such alignment allows for more uniform and comprehensive guidance of the upstream airflow F in thrust phase A and the reverse airflow F-INV in reverse thrust phase B.

[0060] Referring to Figure 6, as previously described, each junction 19 connects the thick portion 15 and the thin portion 17, and each junction leading edge 20 connects the upstream leading edge 16 and the downstream leading edge 18. The junction 19 is configured to assist in separating the reverse airflow F-INV from the thin portion 17. More precisely, the junction 19 makes it possible for the reverse airflow F-INV to separate in a swirling manner after passing through the fan 3. In fact, the reverse airflow F-INV circulates at the intake lip 13, its direction forming an angle of 30° to 45° with the longitudinal axis X.

[0061] In the example of Figure 6, the boundary portions 19 extend with equal circumferential lengths to ensure uniform and comprehensive action on the reverse airflow F-INV. Furthermore, the boundary leading edges 20 preferably have the same shape, with the boundary leading edges 20 connecting the same upstream leading edge 16 referred to as "right boundary leading edge 20-1" and "left boundary leading edge 20-2," respectively, oriented in opposite directions along the longitudinal axis of symmetry. Specifically, on each radial cross-section of the boundary portion 19, the boundary leading edge 20 of the boundary portion 19 is defined by the point where the inlet lip 13 is located most upstream. It goes without saying that at least a portion of the boundary portion 19 can adopt different shapes and / or dimensions.

[0062] In the example of Figure 6, each boundary leading edge 20 extends along a separation axis X20 at an angle α of 35° to 70° with the longitudinal axis X, in the projection of the tangential plane PV at the inlet lip 13. The angle α of the right boundary leading edge 20-1 is equal to and opposite in direction to the angle α of the left boundary leading edge 20-2. Advantageously, the flow direction of the reverse airflow F-INV is substantially perpendicular to the right boundary leading edge 20-1, thereby promoting the separation of the reverse airflow F-INV. The flow direction of the reverse airflow F-INV preferably forms an angle between 80° and 100° with the separation axis X20 of the right boundary leading edge 20-1. Needless to say, the reverse airflow F-INV can also alternately circulate substantially perpendicular to the left boundary leading edge 20-2 instead of the right boundary leading edge 20-1.

[0063] Referring to Figure 6, the leading edge 14 of the intake lip 13 is composed of an upstream leading edge 16, a boundary leading edge 20, and a downstream leading edge 18, forming a wavy closed curve, preferably composed of a wedge shape CH. The wedge shape CH is equivalent to a combination of the upstream leading edge 16, two adjacent downstream leading edges 18, and two boundary leading edges 20 connecting them. The advantage of this shape is its simple structure, with two longitudinally separated profiles, which are used for thrust stage A and reverse thrust stage B, respectively.

[0064] Referring to Figure 7, the air intake lip 13 includes a housing 21, which is defined in each radial plane by a radius of curvature at its leading edge 14, the radius of curvature varying along the circumference of the air intake lip 13. More specifically, the housing 21: On each radial plane PR1 of the thick portion 15, it is defined by the radius of curvature R of the upstream leading edge 16, on each radial plane PR2 of the thin portion 17, it is defined by the radius of curvature r at the downstream leading edge 18, and On each radial plane PR3 of the junction portion 19, it is defined by the radius of curvature R of the junction leading edge 20 * defined.

[0065] As shown in FIG. 7, the radius of curvature R at the upstream leading edge 16 varies with the circumference of the thick portion 15 and is maximum at the upstream point P16. Similarly, the radius of curvature r at the downstream leading edge 18 varies with the circumference of the thin portion 17 and is minimum at the upstream point P18. Preferably, the radii of curvature R and r satisfy the following relationship: R > 1.5 * r, more preferably R < 3 * r, and preferably 1.8 * r < R < 2.2 * r. Thus, the thickness of the thick portion 15 near the upstream leading edge 16 is substantially twice the thickness of the thin portion 17 near the downstream leading edge 18. The radius of curvature R of the junction leading edge 19 * decreases successively from upstream to downstream, preferably linearly, and satisfies the following relationship: r < R * < R. This can not only promote the separation of the upstream airflow F but also promote the separation of the reverse airflow F - INV, while ensuring the continuity and aerodynamic performance of the intake lip 13.

[0066] Referring to FIGS. 4 and 5, the thickness E of each thick portion 15 is preferably greater than the thickness e of the thin portion 17 in the same transverse plane PT3 downstream of the downstream leading edge 18, and the same is true in the transverse planes PT1 and PT2. On the other hand, each junction portion 19 includes a thickness E in the transverse plane PT3 * , which can satisfy the following relationship: E < E * < E. As shown in FIG. 5, each thick portion 15 preferably projects inwardly relative to the thin portion 17 in the transverse plane PT3. Thus, the thick portion 15 and the thin portion 17 form a circulation channel for the upstream airflow F and the reverse airflow F - INV along the entire intake 1. In addition, the intake 1 retains an aerodynamic external shape similar to the prior art, except for the internal shape being changed.

[0067] The method of using the aircraft propulsion assembly 8 in the thrust phase A and the reverse thrust phase B according to the present invention is described below.

[0068] Referring to FIG. 2A, in the thrust phase A, for example, under takeoff or cruise conditions, the blade direction of the variable pitch fan 3 is such that the airflow circulates from upstream to downstream. The upstream airflow F circulating from upstream to downstream reaches the upstream leading edge 16 of the thick portion 15, and the upstream leading edge 16 separates the upstream airflow F into an external airflow F - EXT and an internal airflow F - INT. The thick portion 15 is conducive to separating the upstream airflow F, thereby introducing the internal airflow F - INT into the turbine engine 7 to provide thrust.

[0069] Referring to Figure 2B, during the reverse thrust phase B, such as during braking or landing, the blade pitch of fan 3 changes to reverse the direction of the secondary airflow F2 in the secondary airflow channel 5. The reverse airflow F-INV thus circulates from downstream to upstream and is driven by fan 3 to rotate. The reverse airflow F-INV then reaches the downstream leading edge 18 of thin portion 17 and the boundary leading edge 20 of boundary portion 19, which together facilitate its separation from the inlet lip 13. This forms a separation zone ZD in contact with the inlet lip 13, preventing any localized low pressure that would be detrimental to the reverse thrust B.

[0070] The switch from thrust phase A to reverse thrust phase B is simple and quick, requiring only an adjustment of the direction of fan 3 blades. Unlike existing technologies, there is no need to move or deform the air intake 1. The shape of the air intake 1 remains unchanged between thrust phase A and reverse thrust phase B.

[0071] Figures 8A, 8B, 8C, and 8D illustrate other embodiments of the invention described above. In the example of the elliptical nacelle 2 along the longitudinal axis X in Figure 8A, the upstream point P16 of the upstream leading edge 16 belongs to the ellipse C1' in the transverse plane PT1, with the longitudinal axis X passing through the center of the ellipse C1'. Similarly, the upstream point P18 of the downstream leading edge 18 belongs to the ellipse C2' in the transverse plane PT2, with the longitudinal axis X passing through the center of the ellipse C2'. It goes without saying that the upstream point P16 of the upstream leading edge 16 can belong to a closed curve of any shape in the transverse plane PT1, rather than the circle C1 in Figure 5 and the ellipse C1' in Figure 8A, in order to particularly suit the shape of the nacelle 2. The upstream point P18 of the downstream leading edge 18 is similarly described above. It goes without saying that the closed curves of the upstream point P16 of the upstream leading edge 16 and the upstream point P18 of the downstream leading edge 18 may differ.

[0072] Furthermore, it goes without saying that the upstream point P16 of the upstream leading edge 16 may not be aligned on the transverse plane PT1. The same applies to the upstream point P18 of the downstream leading edge P18. Therefore, in the example of Figure 8B, the upstream point P16 belongs to the inclined plane PT1', which forms an angle β with the longitudinal axis X on the circumferential plane. In this example, the upstream point P18 of the downstream leading edge 18 belongs to the inclined plane PT2', which is parallel to the inclined plane PT1'. Figure 8C shows another example where the upstream points P16 and P18 of the upstream and downstream leading edges of 16 and 18 belong to the curved closed curves PT1" and PT2" on the circumferential plane, which are concave in shape and, in this example, concave upstream. It goes without saying that the upstream point P16 of the upstream leading edge 16 can be aligned on the transverse plane PT1, but the upstream point P18 of the downstream leading edge 18 is not aligned, or, as shown in Figure 8D, the upstream point P16 is aligned in the opposite direction. In this example, the upstream point P18 of the downstream leading edge 18 is aligned in the transverse plane PT2, but the upstream point P16 of the upstream leading edge is not aligned. This allows for the creation of wedges of different lengths.

Claims

1. An air intake (1) of a nacelle (2) of an aircraft propulsion assembly (8), the aircraft propulsion assembly (8) extending downstream along a longitudinal axis (X) and including a turbine engine (7), the turbine engine (7) including a radially inner main airflow passage (4) and a radially outer secondary airflow passage (5), the main airflow passage (4) and the secondary airflow passage (5) respectively guiding the main airflow (F1) and secondary airflow (F2) from upstream to downstream during the thrust phase (A), the turbine engine (7) including, upstream, a fan (3) rotatably mounted about the longitudinal axis (X), the aircraft propulsion assembly (8) including... Includes a thrust reversing device configured to change the secondary airflow (F2) into a reverse airflow (F-INV) circulating from downstream to upstream in the secondary airflow channel (5) during the reverse thrust phase (B). The nacelle (2) extends outward around the turbine engine (7), and the nacelle (2) includes an air inlet (1) at its upstream end. The air inlet (1) extends circumferentially around a longitudinal axis (X) and includes an inner wall (11) facing the longitudinal axis (X) and an outer wall (12) opposite to the inner wall (11). The inner wall (11) and the outer wall (12) are connected upstream by an air inlet lip (13). The air inlet (1) is characterized in that: The intake lip (13) includes a thickness defined radially relative to the longitudinal axis (X), and includes a plurality of thick portions (15) and a plurality of thin portions (17) alternately distributed on the circumference of the intake lip (13). Each thick section (15) includes an upstream leading edge (16) configured to separate the upstream airflow (F) circulating from upstream to downstream into an external airflow (F-EXT) guided by the outer wall (12) and an internal airflow (F-INT) guided by the inner wall (11) to facilitate the thrust phase (A). Each thin section (17) includes a downstream leading edge (18) located longitudinally downstream of each upstream leading edge (16), and the downstream leading edge (18) is configured to separate the reverse airflow (F-INV) at the inlet lip (13) to facilitate the reverse thrust phase (B). The air intake lip (13) includes the outer shell (21): On each radial plane (PR1) of the thick portion (15), the outer shell (21) is defined by the radius of curvature R of the upstream leading edge (16). On each radial plane (PR2) of the thin portion (17), the outer shell (21) is defined by the radius of curvature r of the downstream leading edge (18). The radius of curvature R and the radius of curvature r satisfy the following relationship: R > 1.5 * r.

2. The air inlet (1) according to claim 1, wherein the air inlet lip (13) includes a plurality of boundary portions (19) extending between each thick portion (15) and each thin portion (17), each boundary portion (19) including a boundary leading edge (20) to separate swirling reverse airflow (F-INV) thereby promoting the reverse thrust phase (B).

3. The air inlet (1) according to claim 2, wherein each junction leading edge (20) extends along a separation axis (X20) forming an angle (α) with the longitudinal axis (X) of 35° to 70° in the projection of the tangent plane (PV) of the air inlet lip (13).

4. The air inlet (1) according to claim 1, wherein the air inlet lip (13) includes a wavy leading edge (14).

5. The air inlet (1) according to claim 1, wherein the upstream leading edge (16) of each thick portion (15) includes a convex profile extending circumferentially relative to the longitudinal axis (X), the convex surface of the convex profile facing upstream.

6. The air inlet (1) according to claim 1, wherein the downstream leading edge (18) of each thin portion (17) includes a concave profile extending circumferentially relative to the longitudinal axis (X), the concave surface of the concave profile facing upstream.

7. The air inlet (1) according to claim 1, wherein, On at least one transverse plane (PT3) downstream of the downstream leading edge (18), each thick portion (15) includes a radial thickness (E) that is greater than the radial thickness (e) of each thin portion (17).

8. An aircraft propulsion assembly (8) extending from upstream to downstream along a longitudinal axis (X) and including a turbine engine (7) including a radially inner main airflow passage (4) and a radially outer secondary airflow passage (5), wherein during a thrust phase (A), the main airflow passage (4) and the secondary airflow passage (5) are configured to guide a main airflow (F1) and a secondary airflow (F2) from upstream to downstream, respectively, wherein the turbine engine (7) includes a fan (3) rotatably mounted about the longitudinal axis (X) at its upstream end, the aircraft propulsion assembly (8) including a thrust reversing device configured to change the secondary airflow (F2) into a reverse airflow (F-INV) circulating from downstream to upstream in the secondary airflow passage (5) during a reverse thrust phase (B), the aircraft propulsion assembly (8) including a nacelle (2) extending outward around the turbine engine (7), the upstream end of the nacelle (2) including an air inlet (1) according to claim 1.

9. A method of using the air inlet (1) of the nacelle (2) of the aircraft propulsion assembly (8) according to claim 1, wherein: During the thrust phase (A), each thick portion (15) of the inlet lip (13) separates the upstream airflow (F) circulating from upstream to downstream into an external airflow (F-EXT) guided by the outer wall (12) and an internal airflow (F-INT) guided by the inner wall (11), and During the reverse thrust phase (B), each thin section (17) of the inlet lip (13) separates the reverse airflow (F-INV) flowing from downstream to upstream at the inlet lip (13).

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