Improved acoustic attenuation device for aircraft propulsion devices

Abstract

Propulsion assembly for an aircraft, comprising a turbomachine (1), an attachment strut (40) and a structural element (10) carrying the turbomachine (1) by the attachment strut (40), the turbomachine having at least one rotating part (30) rotating about an axis of rotation (A), the rotating part (30) being arranged upstream of the structural element (10) and of the attachment strut (40) so that the air jet exiting from the rotating part (30) impacts the structural element (10) and the attachment strut (40) in the wake thereof, the leading edge of the structural element (10) and / or of the attachment strut (40) locally comprising at least one acoustic attenuation device (50, 60, 70, 80) arranged at least partially in the wake of the rotating part (30), the acoustic attenuation device being a partial modification of the structure and / or of the profile of the leading edge (11).

Description

Technical Field

[0001] This invention relates to the general field of turbine engines, and more specifically to large-diameter aircraft turbojet and turboprop engines. In particular, this invention relates to a propulsion assembly for an aircraft comprising such a turbojet engine and / or turboprop engine. Background Technology

[0002] It is anticipated that next-generation commercial aircraft will utilize turbojet engines with high bypass ratios (BPRs) (e.g., greater than 10) and large diameters (i.e., greater than 1.5 m) to increase their propulsive efficiency and reduce their fuel consumption and gaseous pollutant emissions. It should be noted that the term "turbo engine" encompasses both "turbojet engine" and "turboprop engine," referring to a gas turbine device that provides thrust through the reaction of a high-speed ejection of hot gas.

[0003] Different types of turbine engines can be used, especially ducted and non-ducted turbojet engines:

[0004] - Ultra-high bypass ratio (UHBR): A ducted turbojet engine with a fixed-pitch fan impeller, with or without a fan reduction gearbox, such as... Figure 1A As shown,

[0005] - Variable Pitch Fan (VPF): A ducted turbojet engine equipped with a variable pitch fan.

[0006] - Reverse Rotating Open Rotor (CROR): A non-ducted turbojet engine with (at least) two reverse rotating variable-pitch propellers, such as... Figure 1B As shown,

[0007] - Unbypass stator fan (USF): An unbypass turbojet engine with a variable pitch propeller wheel and a fixed or variable pitch straightener wheel (stator).

[0008] Non-ducted turboprop engines can also be used. It should be noted that the term "turboprop engine" refers to a gas turbine device that obtains thrust primarily through the traction force of a variable-pitch propeller.

[0009] However, a major drawback of these integrated architectures on commercial aircraft is their acoustic impact, namely noise levels. The sound levels emitted by aircraft during takeoff and landing are subject to increasingly stringent international regulations to limit their sound footprint near airports.

[0010] One of the main noise sources of turbojet engines and large-diameter turboprop engines is related to their integration or installation on aircraft, especially on or under the wings. Figure 1A and Figure 1B Two examples of turbojet engines (ducted and non-ducted) with a large diameter D > 1.5 m integrated on the wing 10 of an aircraft are shown. The turbojet engine 1 is fixed to the wing 10 of the aircraft via struts 40, and the wing 10 itself is fixed to the fuselage 20 of the aircraft. The ducted turbojet engine 1 ( Figure 1A This includes a fan 30 surrounded by a nacelle 32. A non-ducted turbojet engine 1 ( Figure 1B It includes two counter-rotating propellers 31.

[0011] The integration of these large-diameter turbojet engines and / or turboprops increases the interaction between the airflow accelerated by the rotating components, namely the turbojet engine's fan 30 or propeller 31 (which generates a high-speed air jet), and the wing 10 (particularly the leading edge 11, particularly the leading edge line 11a), engine struts (or pylons) 40, high-lift devices 12, and other aircraft components that generate additional noise sources. In fact, the size of these turbojet engines allows the rotating components to be positioned upstream of and opposite the leading edge 11 of the wing 10, so that the turbulence generated in the wake of the fan 30 (or propeller 31) directly impacts the leading edge 11. The turbulence generated in the wake of the fan 30 or propeller 31 is caused by… Figure 1A and 1B The spiral S in the diagram represents noise, and the generated noise is represented by the dashed arc. It should be noted that jet-wing interaction produces broadband noise.

[0012] Furthermore, in the case of ducted turbojet engines (UHBR or VPF type), the turbojet and / or turboprop engine architecture has a short and thin nacelle 32, and in the case of non-ducted turbojet engines, there may not even be a nacelle (e.g., CROR type). This means that the surface area that can accommodate acoustic treatments, such as honeycomb resonators or absorbing materials, is significantly reduced, and therefore noise reduction measures are also reduced.

[0013] Therefore, a device is needed that can at least partially overcome the above-mentioned disadvantages. Summary of the Invention

[0014] This disclosure relates to a propulsion assembly for an aircraft, including a turbine engine, an attachment strut, and a structural element carrying the turbine engine via the attachment strut. The turbine engine includes at least one rotating component configured to rotate about a rotation axis of the turbine engine. The at least one rotating component is disposed upstream of the structural element and the attachment strut such that an air jet exiting from the rotating component impinges on the structural component and the attachment strut in its wake. The leading edge of the structural element and / or the attachment strut partially includes at least one acoustic attenuation device, which is at least partially disposed in the wake of the rotating component. The acoustic attenuation device is a partial modification of the structure and / or profile of the leading edge.

[0015] In some embodiments, the turbine engine is a turbojet engine or a turboprop engine. In this disclosure, the terms "upstream," "downstream," and their derivatives are defined according to the normal flow direction of air through the turbine engine, along the turbine engine's axial direction, i.e., along the turbine engine's axis of rotation. For example, when the rotating component is a turbine engine fan and the structural element is an aircraft wing, the fan is positioned upstream of the wing, particularly upstream of the wing's leading edge, such that air is first drawn in by the fan and then discharged downstream of the fan along the direction of the wing.

[0016] Additionally, "set in the wake" should be understood as a portion of the wing's leading edge being positioned in the path of the air exhausted by the fan and flowing downstream therefrom, and thus impacting that portion of the leading edge.

[0017] Furthermore, "local" should be understood as meaning that the acoustic attenuation device does not extend along the entire length of the leading edge of the structural element, but only along a portion of that leading edge. In other words, the structure and / or profile of the leading edge are modified only locally downstream, particularly in the wake of rotating components. Preferably, at least 30% of the length of the leading edge of the structural element does not include the acoustic attenuation device.

[0018] Preferably, a large portion of the acoustic attenuation device is disposed in the wake of the rotating component, for example, at least 70% of the length of the device along the leading edge.

[0019] The fact that the sound attenuation device is at least partially disposed in the wake of the rotating component makes it possible to attenuate noise generated by air impacting the leading edge of structural elements and / or attached struts. In particular, when a ducted or non-ducted turbine engine is mounted under or on the wing of an aircraft, the propulsion assembly according to this disclosure enables the reduction of acoustic impact from the ducted or non-ducted turbine engine. Furthermore, the fact that only the leading edge of a structural element (e.g., an aircraft wing) is modified locally makes it possible to limit the effect of the device on the aerodynamics of the wing and the aircraft's performance, especially when these modifications are on moving parts of the wing. Moreover, this local modification allows the noise reduction device to be adapted to the local characteristics of the flow (or jet) affecting the wing's leading edge. Furthermore, the fact that the structure and / or profile of the leading edge are modified makes the device a passive noise reduction device, eliminating the need for exhaust systems or dedicated active sensors with energy costs.

[0020] In some embodiments, local modifications to the structure and / or contour of the leading edge are non-uniform along the leading edge line.

[0021] Therefore, the shape and / or structure of the leading edge can be locally adjusted based on the local characteristics of the airflow or air jet at the impact leading edge.

[0022] In some embodiments, the acoustic attenuation device includes a corrugated structure along the leading edge, the corrugated structure having a series of troughs and crests.

[0023] Preferably, the corrugated structure includes at least two troughs and at least two crests. It should be understood that "troughs" and "crests" are considered to be along the chords of the structural element, which are substantially parallel to the axis of rotation of the turbine engine. Therefore, troughs are regions where the chords of the structural element are weaker than those at the crests. These corrugated or serrated structures constitute local modifications to the leading-edge profile, thus providing a passive noise reduction solution.

[0024] In some embodiments, the amplitude h(z) of the corrugated structure and / or the spacing λ(z) between two consecutive wave crests of the corrugated structure vary along the leading edge as a function of distance E, which is the distance between the position z along the leading edge and the rotating component in a direction parallel to the axis of rotation.

[0025] It should be understood that at a given position z along the leading edge, the amplitude h(z) of the corrugated structure corresponds to the distance between the bottom of the trough of the corrugated structure and the peak closest to that position z, which is considered to be along a direction parallel to the axis of rotation. Similarly, the spacing λ(z) corresponds to the distance between the two peaks (or two troughs) of the corrugated structure closest to that position z along the leading edge.

[0026] Since the distance between the rotating component and the leading edge is not constant along the leading edge line, the influence of the air on the leading edge and the local nature of the flow also vary as a function of this distance. Thus, the fact of modifying the amplitude of the corrugated structure and / or the spacing between two successive crests of the corrugated structure makes it possible to adjust the device as a function of this distance and thus as a function of the nature of the flow.

[0027] In some embodiments, the amplitude h(z) of the corrugated structure is such that 0.005c(z) < h(z) < 0.5c(z), where c(z) is the value of the chord of the structural element or of the attachment strut as a function of the position z along the leading edge. This relationship makes it possible to limit the mechanical shock of the corrugated structure or of the serrated structure.

[0028] In some embodiments, the acoustic attenuation device makes the leading edge locally include a porous material.

[0029] The porous material may be a metal foam. A porous material such as a metal foam has good acoustic properties and the advantage of effectively reducing broadband noise, particularly broadband noise at low frequencies. This configuration corresponds to the locally modified part of the leading edge structure and also makes the device a passive acoustic attenuation device. Preferably, the dimensions and position of the leading edge region having such a material are similar to the dimensions and position defined in the case of the corrugated structure, particularly the dimension L, which corresponds to the length along the leading edge line over which the porous material extends, and the dimension h, which corresponds to the length of the porous material in the direction of the chord of the support element.

[0030] In some embodiments, the porous material has a porosity t(z) that varies along the leading edge.

[0031] Porosity is the ratio of the volume occupied by air to the total volume of the porous material. In the same way as for the corrugated structure, these variations in porosity make it possible to adjust the absorption properties of the material as a function of the flow characteristics of the jet / wake generated by the stator / rotor blades of the rotating component upstream of the structural element. When the acoustic attenuation device is applied to an aircraft wing, the porosity of the porous material closest to the aircraft fuselage is preferably lower than the porosity of the porous material furthest from the fuselage.

[0032] In some embodiments, the space between two crests of the corrugated structure is at least partially filled with a porous material.

[0033] This configuration makes it possible to combine the modification of the profile and the modification of the leading edge structure, thus further improving the effectiveness of the acoustic attenuation device.

[0034] In some embodiments, the structural element is an aircraft wing and the acoustic attenuation device extends over a distance L of the wing such that L < 2.5D, where D is the diameter of the rotating component of a turbomachine.

[0035] In some embodiments, the interval λ(z) and / or amplitude h(z) between two consecutive peak values ​​of the corrugated structure closest to the aircraft fuselage is smaller than that of the corrugated structure furthest from the fuselage.

[0036] When the structural element is a wing fixed to the fuselage, the distance between the wing's leading edge and the rotating components is typically smaller near the fuselage, i.e., near the wing root or embedded portion. Therefore, the fact that reducing the interval between two consecutive peak values—in other words, reducing the wavelength of the corrugated structure—and / or reducing the amplitude of the corrugated structure allows acoustic attenuation devices to be adapted to this configuration.

[0037] In some embodiments, at least one acoustic attenuation device includes a single trough that extends a distance L along the leading edge of the wing such that L ≤ 2.5D.

[0038] With this configuration, the modification of the leading edge does not appear in the form of a corrugated structure (including at least one trough and one crest), but rather as a single trough that extends a greater distance along the leading edge line than the trough of a corrugated structure. This configuration makes it possible to locally modify the aerodynamic profile of the wing. It should be noted that the leading edge may include two acoustic damping devices, thus two of these troughs are positioned in different areas along the leading edge line, preferably at the location where propeller blade tip vortices impact the wing. Alternatively, the wing sweep angle can be locally altered, thereby locally increasing the distance between the leading edge and the rotating components.

[0039] This increased distance makes it possible to reduce airflow turbulence before it interacts with the wing leading edge, thus enabling effective noise reduction. Furthermore, the increased sweep amount reduces the correlation of noise sources along the leading edge. In the same manner as with corrugated structures, the maximum amplitude h(z) of the trough, in other words, the maximum depth of the trough, can satisfy the relationship 0.005c(z). <h(z)<0.5c(z)。

[0040] In some embodiments, the leading edge locally includes at least a first acoustic attenuation device and at least a second acoustic attenuation device, the at least first acoustic attenuation device and the second acoustic attenuation device extending along the leading edge by distances L1 and L2, respectively, such that L1+L2<2.5D.

[0041] Each of the first and second acoustic attenuation devices can include a corrugated structure or a single trough structure. Furthermore, the number of acoustic attenuation devices along the leading edge is not limited to two, but can be more. For example, n acoustic attenuation devices can be locally arranged along the leading edge such that L1+L2+…+Ln<2.5D.

[0042] In some embodiments, the cover is configured to move from a closed position where the acoustic attenuation device is covered by the cover to an open position where the acoustic attenuation device is not covered.

[0043] The cover can be a movable fairing, a deformable system at the leading edge, or a leading edge slat. This cover only allows the corrugated structure to be visible or active during certain phases of flight, such as takeoff and landing. This makes it possible to conceal the corrugated structure, thus providing a smooth leading edge during cruise, that is, outside of the takeoff and landing phases. The advantage of concealing the corrugated structure during cruise is that it eliminates their impact on overall aerodynamic performance without requiring noise reduction.

[0044] In some embodiments, the diameter D of the rotating component of the turbine engine is such that D > 1.5 m.

[0045] In some embodiments, the turbine engine includes a stationary component disposed downstream of the rotating component, to which an attachment strut is fixed. The stationary component may be a straightener for the airflow exiting the rotating component.

[0046] This disclosure also relates to aircraft including a propulsion assembly according to any of the foregoing embodiments. Attached Figure Description

[0047] The invention and its advantages will be better understood by reading the following detailed description of various embodiments of the invention given by way of non-limiting examples. This description refers to the accompanying drawings, in which:

[0048] Figure 1A and 1B This shows the front and top views of the propulsion components based on existing technology.

[0049] Figure 2 This is a top view of the propulsion assembly according to a first embodiment of the present invention.

[0050] Figure 3 This is a top view of a propulsion component according to a modified example of the first embodiment of the present invention.

[0051] Figure 4 A top view showing a propulsion assembly according to another modified example of the first embodiment of the present invention.

[0052] Figure 5 This is a top view of the propulsion assembly according to a second embodiment of the present invention.

[0053] Figure 6 This represents a top view of a propulsion assembly based on a modified example incorporating the first and second embodiments of the present invention.

[0054] Figure 7 This is a top view of the propulsion assembly according to a third embodiment of the present invention.

[0055] Figure 8 A top view showing a modified example of a propulsion component according to a third embodiment of the present invention.

[0056] Figure 9 This is a top view of the propulsion assembly according to a fourth embodiment of the present invention.

[0057] Figures 10A to 10C These represent different examples of aircraft including propulsion components according to any embodiment of the present invention, as observed from the foregoing. Detailed Implementation

[0058] Reference Figures 2 to 4 A first embodiment of this disclosure is described. It should be noted that the remainder of the specification relates to propulsion assemblies including turbojet engines. However, this example is not limiting, and the invention can also be applied to propulsion assemblies including turboprop engines.

[0059] Figure 2 The propulsion assembly shown includes a non-ducted turbojet engine 1, which has rotating parts and is attached to a mounting bracket or strut 40 (in... Figure 2 (Not visible in the image) Fixed to a structural element. In this example, the structural element is the aircraft wing 10, and the turbojet engine 1 is fixed below the wing 10. The rotating component of the turbojet engine 1 includes a counter-rotating propeller 31 movable about the axis of rotation A. The spatial reference frame includes an axis X, substantially parallel to the axis of rotation A, corresponding to the main axis of the fuselage 20, and an axis Z, perpendicular to the axis X, corresponding to the longitudinal direction of the wing 10 extending from its root 10a, fixed to the fuselage 20, to its opposite end 10b. In the absence of a dihedral on the wing, plane XZ corresponds to a horizontal plane, which includes the leading edge line 11a of the wing 10. In the presence of a dihedral, plane XZ will not be horizontal, but will include the leading edge line 11a. The front view is a view parallel to the axis X, and the top view is a view perpendicular to the plane XZ. Additionally, the upstream-downstream direction corresponds to the direction of airflow entering the rotating component at velocity U and then exiting the rotating component, toward the leading edge 11 of the wing 10, along the axis of rotation a, in other words, along the axis X. The propeller 31 is positioned upstream of the leading edge 11 and is opposite to the leading edge along the axis X.

[0060] The propulsion component according to this embodiment and Figure 1A and Figure 1BThe difference in the components shown is that they include acoustic attenuation devices comprising corrugated or serrated structures locally along the leading edge 11a. These corrugated structures extend along the leading edge 11a in length L such that L < 2.5D, where D is the diameter of the turbojet engine 1, that is, the diameter of the propeller 31 in the case of a non-ducted turbojet engine, or the diameter of the air intake of the nacelle 32 in the case of a ducted turbojet engine, equivalent to the diameter of the rotating components. It should be noted that the accompanying drawings do not show the machine and the dimensions of the turbojet engine, particularly its diameter D, at true scale; these dimensions have been deliberately exaggerated for visibility and description. For example, the airfoil / wing span of a 200-seat commercial aircraft is approximately 15 to 20 meters, and the engine diameter is 2 meters.

[0061] Apart from the corrugated structure 50, the leading edge 11a has an unmodified profile, corresponding to a typical profile or neutral profile, and does not include any acoustic attenuation devices. The neutral profile is formed by... Figure 2 The dashed lines in the figure indicate this. The length L is such that a large portion, preferably at least 70% of the length L of the corrugated structure 50, is located in the wake of the rotating component of the turbojet engine (that is, the propeller 31 in this example). In other words, the virtual cylinder with diameter D and axis A extending downstream of the propeller 31 includes a portion of the leading edge 11 and, in particular, includes at least 70% of the length L of the acoustic attenuation device.

[0062] The corrugated structure 50 is characterized by a series of troughs 51 and crests 52. The troughs 51 correspond to localized depressions downstream of the leading edge 11, relative to the unmodified profile of the leading edge in the chord c direction of the wing (see [reference]). Figure 2 The dashed line in the diagram corresponds to the direction of axis X. Crest 52 corresponds to the bulge or overhang upstream of the leading edge, relative to the unmodified profile of the leading edge in the chord c direction of the wing (see [reference]). Figure 2 The dashed line in the diagram corresponds to the direction of the axis X.

[0063] The height h refers to the following distance: in the direction perpendicular to the neutral leading edge 11a, or in the direction parallel to the engine axis A, between consecutive troughs 51 and crests 52, more precisely, between the bottom of a trough 51 and the end of a crest 52. In other words, the height h corresponds to the amplitude of the corrugated structure 50. The length λ is the distance between two consecutive troughs 51 (or between two consecutive crests 52) in the direction parallel to the neutral leading edge 11a. In other words, the length λ corresponds to the wavelength of the corrugated structure 50.

[0064] exist Figure 2 In the example shown, the propulsion assembly includes a single acoustic attenuation device extending L along the leading edge line 11a. Figure 3 An alternative example of the first embodiment is shown, wherein the propulsion assembly includes two sound attenuation devices extending along the leading edge 11a by distances L1 and L2, respectively, such that L1 + L2 < 2.5D. According to this alternative, the turbojet engine 1 is a ducted turbojet engine including rotating components, in this case a fan 30 and a nacelle 32. The turbojet engine 1 is fixed above the wing 10 by an attachment strut 40. The respective corrugated structures 50a and 50b of the two sound attenuation devices are disposed on either side of the strut 40, in the wake of the fan 30, such that the air jet ejected from the fan 30 (for clarity, in...) Figure 3 (And not shown again in the figure below) Impact corrugated structures 50a and 50b. In this example, corrugated structures 50a and 50b each include two troughs 51 and two crests 52. However, it is also possible for each acoustic attenuation device 50a and 50b to have more troughs 51 and crests 52.

[0065] exist Figure 2 and Figure 3 In the example of the first embodiment shown, the corrugated structure is uniform over the entire length L, and is also the same over lengths L1 and L2. The terms "uniform" or "the same" can be understood to mean that the amplitude h and wavelength λ are constant along the leading edge line 11a.

[0066] Figure 4 A modified example of the first embodiment is shown, wherein the propulsion assembly further includes two acoustic attenuation devices. The turbojet engine 1 is also a non-ducted turbojet engine, mounted above the wing 10. Figure 3 The examples shown are different; the corrugated structures 50a and 50b are not identical, but they have different amplitudes h and / or wavelengths λ. More specifically, the amplitude h(z) and wavelength λ(z) vary as a function of the position z along the leading edge line 11a in the Z direction.

[0067] It should be noted that distances E1 and E2 each correspond to the distance in the X direction between a point along the leading edge line 11a (e.g., the crest 52 of the corrugated structure) and the rotating component. More specifically, distance E2 corresponds to the distance between the rotating component and the leading edge 11 at the horizontal level of the trailing edge of the first radial end of the rotating component, which corresponds to the end closest to the fuselage 20, and distance E1 corresponds to the distance between the rotating component and the leading edge 11 at the horizontal level of the second radial end of the rotating component, which is radially opposite to the first radial end and corresponds to the end farthest from the fuselage 20.

[0068] Given the profile of the wing 10 (whose cross-section decreases from the root 10a to the tip 10b) and the sweep angle of the wing 10, the distance E2 near the fuselage 20 is less than the distance E1 furthest from the fuselage 20. Thus, the size of the vortices generated by the turbulence downstream of the rotating components and impinging on the leading edge 11, characterized by the integral scale ∧ (as Figure 2 shown), varies depending on the position z along the leading edge line 11a. In fact, near the trailing edge of the rotating components, the width of the wake is small and it has the characteristics of small vortices. Then the turbulence develops downstream, gradually increasing the size of the vortices, i.e., the integral scale Λ. When the distance between the rotating components 30, 31 and the leading edge 11 is small, the size of the vortices impinging on the leading edge 11 is also small because these vortices can develop to a lesser extent than when this distance is larger.

[0069] In the present case, therefore, it is preferable that for the corrugated structure closer to the aircraft fuselage 20, the wavelength λ(z) and / or the amplitude h(z) are smaller. In the Figure 4 example shown, the wavelength λ1(z) of the corrugated structure 50a and the wavelength λ2(z) of the corrugated structure 50b are such that λ1(z)>λ2(z). In fact, the smaller the distance between the rotating components 30, 31 of the turbojet engine and the leading edge 11 of the wing 10, the more the integral scale Λ of the turbulence downstream of the rotating components (represented in Figure 2 ) decreases. However, the optimal amplitude and wavelength of the corrugated structure depend on the integral scale Λ of the turbulence. Preferably, the wavelength value λ as a function of the position z along the leading edge line 11a approximately satisfies λ(z) = Λ(z) / 2 in order to maximize the acoustic gain.

[0070] Figure 4 The example in Figure 2 shows a case where the propulsion assembly includes two acoustic attenuation devices 50a, 50b, each of which has a different corrugated structure. However, this example is not restrictive, and according to this configuration, the propulsion assembly includes a single device, as shown in the example of

[0071] Figure 5 but it is also possible to have a non-uniform corrugated structure over the length L. The wavelength λ can be, for example, an increasing wavelength from the end of the corrugated structure 50 closest to the fuselage 20 to the end of the corrugated structure 50 furthest from the fuselage 20. Furthermore, the amplitude h of the corrugated structure 50 preferably satisfies 0.005c(z)<h(z)<0.5c(z) at the position z along the leading edge line 11a, where c(z) corresponds to the value of the chord c of the wing 10.

[0071] A second embodiment of the present disclosure will be described with reference to Figure 5

[0072] Figure 5The propulsion assembly shown includes a ducted turbojet engine 1, which includes a nacelle 32 surrounding a fan 30 and secured above the wing 10 by attachment racks or struts 40. The propulsion assembly according to the second embodiment differs from that of the first embodiment in that the acoustic attenuation device causes the leading edge 11 of the wing 10 to partially comprise a porous material 60, preferably a metallic foam. Contrary to the presence of a corrugated structure, the profile of the leading edge line 11a remains unchanged, but the structure of the leading edge 11, particularly the material, is locally altered.

[0073] In the same manner as in the first embodiment, a single acoustic attenuation device can be arranged at a distance L along the leading edge, wherein the porous material can be non-uniform, for example by exhibiting variable porosity along the leading edge line. Porosity is defined as the ratio of the volume occupied by air to the total volume of the porous material. Optionally, according to Figure 5 In the example shown, two acoustic attenuation devices are arranged on either side of the support column 40 in the wake of the fan 30. These devices cause the porous materials 60a and 60b of the acoustic attenuation devices to have different porosities t1(z) and t2(z) respectively, and these porosities are functions of the position z along the leading edge line 11a. In particular, for the same reason as in the corrugated structure, the porosity t2(z) of the porous material 60b closer to the fuselage 20 is lower than the porosity t1(z) of the porous material 60a further away from the fuselage 20. In particular, these variations in porosity allow the noise attenuation to be adjusted as a function of the distance between the leading edge 11 and the rotating component. Furthermore, the thickness h(z) of the porous material, i.e., the distance the porous material extends along the axis X, preferably satisfies the same relationship as the amplitude of the corrugated structure, as a function of a chord, i.e., 0.005c(z). <h(z)<0.5c(z)。

[0074] Figure 6 A configuration combining the first and second embodiments of this disclosure is shown. According to this configuration, the propulsion component includes components similar to... Figure 4 The corrugated structures 50a and 50b shown have a corrugated structure in which the space between the teeth formed by the corrugated structure is partially or completely filled with a porous material, preferably as shown in the figure. Figure 5 The porous materials 60a and 60b described in the illustrated embodiment have the same properties. This configuration makes it possible to modify the profile of the leading edge 11 of the wing 10 without altering or by minimizing such modifications.

[0075] Reference Figure 7 and Figure 8 A third embodiment of this disclosure is described.

[0076] According to this embodiment, the profile of the leading edge 11 of the wing 10 is partially modified to locally increase the distances E1, E2 between the rotor (or stator) of the rotating component of the turbojet engine 1 and the leading edge 11 of the wing 10. Unlike the corrugated structure of the first embodiment, which includes at least one trough and at least one crest, the attenuation device of the third embodiment locally includes a single trough 70. Figure 7 In the example shown, the propulsion assembly includes two sound attenuation devices, each comprising a single trough 70a, 70b located on either side of the attachment strut 40. The troughs 70a and 70b can extend to distances L1 and / or L2, respectively, twice the diameter D of the turbojet engine. Furthermore, for the corrugated structure, the maximum amplitude h(z) of the trough can satisfy the relationship 0.005c(z) < h(z) < 0.5c(z).

[0077] This local increase in distance makes it possible to reduce airflow turbulence before the airflow interacts with the leading edge 11 of the wing 10, thereby improving the noise reduction effect.

[0078] Alternatively, a local increase in the distance between the leading edge 11 and the rotating component can be caused by a local increase of 80 in the sweep angle α of the wing 10, such as... Figure 8 As shown. According to this example, in the wake of fan 30, two local increases 80a and 80b are formed on either side of strut 40 to increase the sweep angle of wing 10. These increases 80a and 80b of the sweep angle have values ​​α” and α’, respectively, such that the enhanced sweep angles are equal to α”+α and α’+α, respectively. The dashed line represents the leading edge line without acoustic attenuation devices, with an unmodified arrow. The values ​​α’ and α” are preferably different so that the modification of the sweep angle adapts to the distance between fan 30 and leading edge 11. The local increase in sweep angle makes it possible to reduce the correlation of noise sources along the leading edge.

[0079] Acoustic attenuation devices according to various embodiments of the present invention can be used in conjunction with de-icing systems that can be reinforced at the troughs and levels of porous materials.

[0080] Figure 9 A modified example of this disclosure is shown, wherein the acoustic attenuation device is disposed on the attachment strut 40, allowing the turbojet engine 1 to be fixed to the fuselage 20 instead of the wing 10. According to this configuration, the structural element is the portion of the fuselage 20 to which the attachment strut 40 is fixed. This configuration is suitable for turbojet engines mounted at the rear end of the fuselage 20, and is referred to as a "tractor" configuration, wherein the propeller 31 (or fan 30 in the case of a ducted turbojet engine) is positioned upstream of the attachment strut 40 in the direction of airflow along the axis of rotation a at velocity U. Figure 9In the example shown, the acoustic attenuation device includes a corrugated structure 50 and a porous material 60.

[0081] Figures 10A to 10C Different types of aircraft 100 to which the propulsion system according to this disclosure can be applied are shown. The invention is particularly applicable to wings 10 with unconventional profiles and shapes, such as low wings whose dihedral angle Δ is scalable over the span, especially with a stronger (dihedral angle Δ') on the inner side of the wing 10. Figure 10A This wing ensures the ground clearance defined in the standards for large-diameter engines, that is, the distance between the engine and the ground. Figure 10B An aircraft with a high wing 10 is shown. Figure 10C An aircraft with an inverted sweep angle α is shown with wings 10.

[0082] Although the invention has been described with reference to specific exemplary embodiments, it will be apparent that modifications and changes may be made to these examples without departing from the general scope of the invention as defined in the claims. In particular, various features of different shown / mentioned embodiments may be combined in other embodiments. Specifically, characteristics relating to parameters described in one embodiment, such as height and length L, L1, and L2, may also be applicable to other embodiments described in this disclosure. Therefore, the description and drawings should be considered illustrative rather than restrictive.

Claims

1. A propulsion assembly for an aircraft, comprising a turbomotor (1), an attachment strut (40), and an aircraft wing (10) carrying the turbomotor (1) by means of the attachment strut (40), the turbomotor including at least one rotating part (30, 31) configured to rotate about a rotation axis (A) of the turbomotor (1), the at least one rotating part (30, 31) being arranged upstream of the wing (10) and the attachment strut (40) such that an air jet discharged from the rotating part (30, 31) impacts the wing (10) and the attachment strut (40) in its wake, a leading edge (11) of the wing (10) locally including at least one acoustic attenuation device (50, 60, 70, 80), the acoustic attenuation device being at least partially arranged in the wake of the rotating part (30, 31), the acoustic attenuation device being a locally modified part of the structure and / or profile of the leading edge (11) and extending over a distance L on the wing (10) such that L < 2.5D, where D is the diameter of the rotating part of the turbomotor (1).

2. The assembly according to claim 1, wherein the acoustic attenuation device comprises a corrugated structure (50) along the leading edge (11), the corrugated structure having a series of valleys (51) and peaks (52).

3. The assembly according to claim 2, wherein the amplitude h(z) of the corrugated structure (50) and / or the spacing λ(z) between two consecutive peaks (52) of the corrugated structure (50) vary as a function of a distance E along the leading edge (11), the distance E being the distance along the direction parallel to the rotation axis (A) between a position z along the leading edge (11) and the rotating part (30, 31).

4. The assembly according to claim 2, wherein the amplitude h(z) of the corrugated structure (50) is such that 0.005c(z) < h(z) < (此处原文有误,应为0.5c(z))0.5c(z), where c(z) is the value of the chord of the wing (10) as a function of the position z along the leading edge (11).

5. The assembly according to claim 1, wherein the acoustic attenuation device makes the leading edge (11) locally include a porous material (60).

6. The assembly according to claim 5, wherein the porous material (60) has a variable porosity t(z) along the leading edge (11).

7. The assembly according to claim 2, wherein the space between two peaks (52) of the corrugated structure (50) is at least partially filled with the porous material (60).

8. The assembly according to claim 1, wherein the at least one acoustic attenuation device comprises a single valley (70), the valley (70) extending over a distance L along the leading edge (11) of the wing (10) such that L < 2.5D.

9. The component according to claim 1, wherein the leading edge (11) partially includes at least a first and at least a second acoustic attenuation device, the first and second acoustic attenuation devices extending along the leading edge (11) by distances L1 and L2, respectively, such that L1+L2<2.5D.

10. The component according to any one of claims 1 to 9, wherein the turbine engine includes a fixed component disposed downstream of the rotating component (30, 31), and the attachment strut (40) is fixed to the fixed component.

11. An aircraft comprising a propulsion assembly according to any one of claims 1-10.

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