Assembly of acoustic sector components

Abstract

The invention relates, inter alia, to the assembly of annular sectors (100) of an annular multi-element acoustic component (10), each sector (100) comprising a plurality of rows of hollow complex acoustic elements (110), each hollow complex acoustic element having a shape tapering between a bottom and an apex, each sector (100) comprising a plurality of first rows and one or more second rows, the first row comprises the same number of hollow complex acoustic elements (110), the second row comprises one less hollow complex acoustic elements (110) than the first row, each second row further comprises a male connecting element (121) on one of the assembly edges (102a) and a female connecting element (122) on the other assembly edge (101a), the female connection element (121) has the same size as the hollow complex acoustic element (110) in the assembly direction (Dc).

Description

Technical Field

[0001] The present invention relates to the general field of acoustic structures or panels. More particularly, but not exclusively, the present invention relates to acoustic attenuating structures for reducing noise generated by aircraft engines, gas turbines or their exhaust. Background Art

[0002] An acoustic attenuation structure generally consists of a plate or skin having an acoustic surface that allows the transmission of the sound waves to be attenuated, a reflective solid plate or skin called a "closed plate", a multi-element acoustic component and a polyhedron arranged between these two walls. The polyhedron generally consists of a set of baffles, for example in the form of a honeycomb; the multi-element acoustic component generally comprises a hollow complex acoustic element, for example a cone, arranged inside a unit cell of the polyhedron. In a manner known per se, such a structure forms a Helmholtz-type resonator capable of attenuating sound waves over a certain frequency range. This type of acoustic attenuation structure is described in particular in document FR 3 108 765 A1.

[0003] In most applications of such acoustic structures, for example in the aerospace sector, multi-element acoustic components must be lightweight in order to limit the mass of the acoustic structure. In order to produce lightweight multi-element acoustic components, it is necessary to use manufacturing methods that are able to produce very thin walls, such as injection molding or stamping under controlled temperature and pressure. However, these methods require special tools and parameters, which limit the size of multi-element acoustic components that can be obtained by these methods.

[0004] The acoustic structure may be intended to cover the inner or outer annular surface of a large component or element, such as a fan case of an aircraft engine. It is therefore necessary to produce a multi-element acoustic component of a plurality of annular sectors, which are then mounted on the surface to be covered, assembled together with the polyhedron and the acoustic skin to form an annular acoustic structure conforming to the surface to be covered.

[0005] Fasteners are used to connect different sectors of a multi-element acoustic component along the perimeter of the surface to be covered.

[0006] However, the design, positioning and assembly of the components of an acoustic structure can be tricky.

[0007] First, the fasteners used increase the mass of the acoustic structure and often represent areas that do not participate in acoustic attenuation. Furthermore, the fasteners used may have aerodynamic effects by disrupting the airflow.

[0008] The relative positioning of the various components of the acoustic structure along the perimeter of the surface to be covered can also be complex, particularly when the hollow acoustic elements or units are hexagonal in shape. Figure 1As shown, there may be gaps between the various parts of the acoustic structure. These gaps represent areas that are not covered by the acoustic component and will therefore not be able to perform its acoustic attenuation function. In addition, without special measures, the assembly edges between different sectors may not be complementary, resulting in additional uncovered areas, such as Figure 1 shown.

[0009] In addition, the uncovered areas also create discontinuities in the acoustic treatment, which will change the sound field structure by repelling energy propagating in the annular acoustic structure. As a result, the degradation in acoustic performance is much greater than that caused by the loss of acoustically functional surface area alone.

[0010] Conversely, during the assembly process, it may be necessary to cut parts of the acoustic structure to avoid unnecessary overlap between sectors and to enable assembly. These cuts are a waste of material and result in unnecessary costs.

[0011] Finally, uncovered areas and overlaps reduce the aerodynamic performance of the acoustic structure by disrupting the airflow and increasing its drag. Summary of the invention

[0012] It is therefore a primary object of the present invention to enable assembly of an acoustic structure while avoiding at least some of the above mentioned problems.

[0013] To this end, the present invention proposes an annular sector of an annular multi-element acoustic component, which extends along an assembly direction between a first assembly edge and a second assembly edge opposite to the first assembly edge, the sector including multiple rows of hollow complex acoustic elements, each hollow complex acoustic element having a shape that gradually narrows between the bottom and the vertex, the hollow complex elements being interconnected by one or more adjacent edges, each row extending from the first assembly edge to the second assembly edge along the assembly direction, the sector being characterized in that it includes multiple first rows, the first rows containing the same number of hollow complex acoustic elements; and one or more second rows, the second rows containing one less hollow complex acoustic element than the first rows, each second row also including a male connecting element on one of the assembly edges and a female connecting element on the other assembly edge, the female connecting element having the same size as the hollow complex acoustic element along the assembly direction.

[0014] By using annular sectors having a first row with the same number of hollow acoustic elements and a second row containing male and female connecting elements with one less hollow acoustic element than the first row, it is ensured that the first assembly edge of the produced annular sectors is complementary to the second assembly edge. Furthermore, by using female connecting elements having the same dimensions as the hollow complex acoustic elements in the assembly direction, it is ensured that the area occupied by the female connecting element assembled with the male connecting element is perfectly adapted between two adjacent sectors without changing the complementarity between the edges of the sectors.

[0015] Furthermore, since the connecting element performs this function, it is no longer necessary to provide an area for the assembly of two adjacent sectors. Thus, the surface area actually available for acoustic attenuation is increased compared to prior art acoustic structures that do not include such connecting elements.

[0016] According to a particular embodiment of the invention, the male connection element has a perforated shape that tapers between the base and the apex.

[0017] Thus, due to the assembly of the sectors, the area not effectively participating in the acoustic attenuation is further limited and the male connection element is able to perform the acoustic attenuation function. More specifically, the male connection element preferably has the same geometry as the hollow complex acoustic element.

[0018] According to another particular embodiment of the invention, the bottom of the hollow complex acoustic element is hexagonal.

[0019] Assembling a multi-element acoustic component comprising a hexagonal hollow complex acoustic element is more difficult than assembling a square hollow acoustic element. Therefore, in the case of a hexagonal hollow complex acoustic element, the sectors of the present invention are particularly useful.

[0020] The invention also relates to an annular multi-element acoustic component comprising a plurality of annular sectors according to the invention assembled in an assembly direction, each male connection element of an annular sector of the acoustic component being inserted into a female connection element of an adjacent sector.

[0021] The positioning of the sectors relative to each other is thus facilitated, the connecting element serving as a reference point for the assembly of the sectors relative to each other. Furthermore, the space occupied by the connecting element is limited and perfectly adapted to the assembly between hollow complex acoustic elements of different sectors.

[0022] According to a particular embodiment of the invention, all sectors are identical.

[0023] "Same sector" means that each sector has the same size, the same shape of hollow complex acoustic elements, the same number of rows of hollow complex acoustic elements, the same number of hollow acoustic elements in each first and second rows, the same offset between rows of hollow complex acoustic elements, the same shape of connecting elements, and the same positioning of connecting elements.

[0024] Therefore, the design and manufacture of the sector is greatly simplified, which is beneficial to the design and manufacture of the entire acoustic structure.

[0025] The present invention also relates to an annular acoustic attenuation structure comprising an annular multi-element acoustic component according to the present invention and an annular polyhedron, the vertices of each hollow complex acoustic element of the multi-element acoustic component being inserted into a cell of the polyhedron.

[0026] Preferably, the assembly of the male connecting element with the female connecting element exists in the volume between the surface defined by the bottom or edge of the hollow complex acoustic element and the surface defined by the vertex of the hollow complex acoustic element. Therefore, the assembly of the male element with the female element does not generate any additional thickness, which makes it possible not to change the aerodynamic performance of the multi-element acoustic component and facilitates the assembly of the multi-element acoustic component with the optional polyhedron or the optional acoustic skin.

[0027] According to a specific embodiment of the invention, the acoustic attenuation structure further comprises a perforated acoustic skin in contact with the bottom of the hollow complex acoustic element.

[0028] According to another specific embodiment of the invention, the annular polyhedron comprises a plurality of annular sectors of polyhedrons assembled along an assembly direction, the length of the annular sectors of the polyhedrons being greater than the length of the annular sectors of the multi-element acoustic component along the assembly direction.

[0029] In practice, the manufacture and assembly of polytopes is less restricted than the manufacture and assembly of multi-element acoustic components because the manufacturing and assembly tolerances of polytopes are looser than those of multi-element acoustic components. Therefore, in order to limit the number of fasteners or operations required to form the polytope, it is sought to assemble a limited number of polytope sectors. In addition, by using polytope sectors that are longer than the multi-element acoustic component sectors, the robustness of the acoustic structure assembly is increased.

[0030] The invention also relates to a method for designing an annular multi-element acoustic component according to the invention, the annular multi-element acoustic component extending around an axial direction and having a defined inner or outer cross-sectional perimeter, each annular acoustic component sector extending in the axial direction between a first circumferential edge and a second circumferential edge, the circumferential edges extending in the assembly direction, the method comprising the following steps:

[0031] · determining the number of annular sectors of the multi-element acoustic component by rounding the ratio of the cross-sectional perimeter of the acoustic component to the maximum theoretical length of an annular sector of the multi-element acoustic component to the next integer;

[0032] · determining a circumferential edge length of each annular sector of the acoustic component;

[0033] · determining a theoretical width of the hollow complex acoustic element along the assembly direction corresponding to a desired acoustic attenuation;

[0034] · determining an integer number of each first row of hollow complex acoustic elements in each annular sector;

[0035] ·Determine the final width of hollow complex acoustic components along the assembly direction.

[0036] The design method according to the invention thus makes it possible to produce a multi-element acoustic component that is easy to assemble and has very small gaps between the sectors. In fact, the invention proposes to slightly adjust the width of the hollow acoustic elements so as to limit the gaps between the sectors, which ultimately improves the acoustic performance of the annular multi-element acoustic component by reducing non-functional areas and limiting discontinuities in the acoustic field. Moreover, by ensuring a constant number of hollow complex acoustic elements per row, complementary axial edges are obtained at the junctions of the annular sectors.

[0037] Finally, the present invention provides a method for manufacturing an annular acoustic attenuation structure, comprising:

[0038] · Designing an annular multi-element acoustic component as described above;

[0039] · preparing an annular sector of the multi-element acoustic component according to the design;

[0040] · Assembling the annular sectors of the multi-element acoustic component with each other and with the annular polyhedron such that each hollow complex acoustic element is arranged in a cell of the polyhedron;

[0041] · The multi-element acoustic component is covered with an acoustic skin to form an annular acoustic attenuation structure including at least the annular multi-element acoustic component, the annular polyhedron and the acoustic skin. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 The assembly of an annular acoustic structure around a cylindrical element without the present invention is schematically illustrated.

[0043] Figure 2 is a partially exploded perspective view of an acoustic structure including a multi-element acoustic component according to one embodiment of the present invention.

[0044] Figure 3 yes Figure 2 A perspective view of a sector of a multi-element acoustic component comprising a connecting element according to one embodiment of the present invention.

[0045] Figure 4 is a cross-sectional view of two acoustic component sectors assembled according to a first variant.

[0046] Figure 5 is a cross-sectional view of two acoustic component sectors assembled according to a second variant.

[0047] Figure 6 is with Figure 1An assembled perspective view of the different multi-element acoustic components shown in FIG.

[0048] Figure 7 is a flow chart describing a method of designing a multi-element acoustic component according to one embodiment of the present invention.

[0049] Figure 8 Schematically illustrates Figure 7 The steps of the design method.

[0050] Fig. 9 yes Figure 2 Schematic partial cross-sectional view of an assembled acoustic structure.

[0051] Implementation

[0052] Figure 2 The acoustic structure 1 according to the invention is illustrated as being assembled on the expandable outer surface of a large-sized annular component 5 extending around the axial direction Da. Of course, if the acoustic structure according to the invention is assembled on the expandable inner surface of the large annular component 5, it does not exceed the scope of the invention.

[0053] The annular component 5 may be, for example, a fan casing of a jet engine, an aircraft fairing, a fuselage element, a wing element, a platform connecting stator blades or an internal flow spacer (IFS).

[0054] The term "annular" here describes a shape that includes at least one developable inner or outer surface extending around an axial direction Da and a complete revolution around said axial direction Da, and has a constant cross-section in every plane perpendicular to said axial direction Da. Thus, the term "annular" can, for example, describe a shape having a cylindrical surface of revolution, such as Figures 1 to 9 shown.

[0055] The annular acoustic structure 1 includes at least one annular multi-element acoustic component 10 and an annular multicellular body 20. The annular multicellular body 20 and the annular multi-element acoustic component 10 each extend in an assembly circumferential direction Dc around an axial direction Da.

[0056] The polyhedron 20 comprises a plurality of cells 210 arranged in rows and separated by partitions 220 forming an array of ribs. The polyhedron 20 is preferably in contact with the surface to be covered of the component 5. The annular multi-element acoustic component 10 comprises a plurality of hollow complex acoustic elements 110 arranged in rows. In a well-known manner, the annular multi-element acoustic component 10 is inserted into the annular polyhedron 20, so that each hollow complex acoustic element 110 of the multi-element acoustic component 10 is inserted into the polyhedron 20 cell 210.

[0057] Preferably, the acoustic structure 1 further comprises an acoustic skin 30 covering the annular multi-element acoustic component 10. The function of the acoustic skin 30 is to allow the sound waves to be attenuated to pass through the interior of the acoustic structure 1. To this end, the acoustic skin 30 comprises a plurality of perforations 31.

[0058] The annular multi-element acoustic component 10 is prepared by assembling a plurality of annular sectors 100 of the annular multi-element acoustic component 10. Preferably, the annular multi-element acoustic component 10 is installed in the annular multicellular body 20 sector by sector.

[0059] Figure 3 An example of an annular sector 100 of an annular multi-element acoustic component 10 is illustrated.

[0060] The annular sector 100 extends along the assembly circumferential direction Dc between a first assembly edge 101a and a second assembly edge 02a opposite the first assembly edge 101a. The first assembly edge 101a of the annular sector 100 is intended to be assembled with the second assembly edge of an adjacent annular sector, and the second assembly edge 102a of the annular sector 100 is intended to be assembled with the first assembly edge of an adjacent annular sector.

[0061] The annular sector 100 also extends between a first circumferential edge 101c and a second circumferential edge 102c in the axial direction Da. The first circumferential edge 101c and the second circumferential edge 102c preferably have the same length Lc.

[0062] The annular sector 100 of the annular multi-element acoustic component 10 includes a plurality of hollow complex acoustic elements 110 distributed in rows. Each row of hollow acoustic elements 110 extends from a first assembly edge 101a to a second assembly edge 102a of the annular sector 100 along the assembly circumferential direction Dc. The hollow complex acoustic elements each have a shape that gradually narrows between the bottom and the vertex, and the hollow acoustic elements are connected to each other by one or more adjacent edges. The hollow complex acoustic element has, for example, a shape of a perforated truncated cone or a perforated truncated pyramid, such as Figures 2 to 9 The bottom of each complex acoustic element 110 is in continuous contact with the bottom of an adjacent complex acoustic element 110 to form a continuous edge array.

[0063] The annular sector 100 extends in a thickness direction De perpendicular to the axial direction Da and the assembly circumferential direction Dc, in a thickness between an upper surface 100a and a lower surface 100b. The upper surface 100a is defined by the bottom of the hollow acoustic element 110 and the lower surface 100b is defined by the vertex of the hollow acoustic element 110. The upper surface 100a thus has a length Lc in the assembly circumferential direction Dc.

[0064] The annular sector 100 of the annular multi-element acoustic component 10 comprises a plurality of first rows of hollow acoustic elements 110, each row having the same number n of hollow acoustic elements 110. Figure 3 In the example shown, the number n of each first row of hollow acoustic elements 110 is seven. The annular sector 100 of the annular multi-element acoustic component 10 also includes one or more second rows of hollow acoustic elements 110, which have one less hollow acoustic element 110 than the first row, that is, the second row or rows of hollow acoustic elements 110 have the same number n-1 of hollow acoustic elements 110. Figure 3 In the example shown, the number n-1 of hollow acoustic elements 110 in each second row is six.

[0065] Each second row of hollow acoustic elements 110 also comprises a male connection element 121 on one assembly edge 101a or 102a of the annular sector 100 and a female connection element 122 on the other assembly edge 101a or 102a. Figure 3 In the example shown, the sector 100 comprises 8 rows of hollow acoustic elements 110 , of which 6 rows are first rows and 2 rows are second rows.

[0066] The male connection element 121 of the annular sector 100 is intended to cooperate with the female connection element of the adjacent annular sector, and the female connection element 122 of the annular sector 100 is intended to cooperate with the male connection element of the adjacent annular sector. The male connection element cooperates with the female connection element by inserting the female connection element. The cooperation of the male connection element of the annular sector of the multi-element acoustic component 10 with the female connection element of the adjacent annular sector fixes the annular sector to the adjacent annular sector.

[0067] The female connection element 122 has the same dimensions along the assembly circumferential direction Dc as the hollow complex acoustic element 110. Thus, the annular sectors can be positioned relative to each other without leaving areas not covered by the hollow complex acoustic element 100 or the female connection element 122, the female connection element 122 inserted into the male connection element completely filling the area between two adjacent annular sectors.

[0068] Preferably, in order to prevent the area covered by the female connecting element 122 inserted into the male connecting element from being lost and to be able to perform the acoustic attenuation function, the male connecting element 121 has a shape similar to that of the hollow complex acoustic element 110, such as Figure 2 and 3As shown. Therefore, the male element 121 has a perforated shape that gradually narrows between the bottom and the apex, the bottom of the male connecting element 121 is located on the same side of the annular sector 100 as the bottom of the hollow complex acoustic element 110, and the apex of the male connecting element 121 is located on the same side of the annular sector 100 as the apex of the hollow complex acoustic element 110. Preferably, the geometric shape of the bottom of the male connecting element 121 is the same as the geometric shape of the bottom of the hollow complex acoustic element 110. Therefore, if the bottom of the hollow complex acoustic element 110 has a hexagonal shape, the bottom of the male connecting element 121 will preferably be a hexagonal shape.

[0069] In a configuration where the male connection element 121 has a similar shape to the hollow complex acoustic element 110, the female connection element 122 may have a flat shape penetrated by a through hole, allowing the male connection element 121 to be inserted and retained, such as Figure 2 and 3 Preferably, the male connecting element 121 is inserted into the female connecting element by applying pressure, so that the male connecting element is clamped by the female connecting element. Preferably, the male connecting element is installed in the female connecting element so that the bottom of the male connecting element contacts the female connecting element.

[0070] according to Figure 4 In the illustrated variant, in a configuration where the male connection element 123 has a shape similar to that of the hollow complex acoustic element 110, the female connection element 124 may also have a shape similar to that of the hollow complex acoustic element 110, i.e., the female connection element 124 has a perforated shape that gradually narrows between the bottom and the apex, the bottom of the female connection element 124 is located on the same side of the annular sector as the bottom of the hollow complex acoustic element 110, and the apex of the female connection element 124 is located on the same side as the apex of the hollow complex acoustic element 110. Therefore, the male connection element 123 is installed in the female connection element 124 so that the bottom of the male connection element 123 contacts the bottom of the female connection element 124, and the shape of the female connection element 124 clamps the shape of the male connection element 123 between the bottom and the apex of the male connection element 123.

[0071] according to Figure 5 In another variant shown, the assembly of the male connecting element 125 with the female connecting element 126 is of the snap-on type.

[0072] Of course, if other male / female connection methods are used, it does not exceed the scope of the present invention.

[0073] In all configurations, the dimension of the male and female connection elements in the thickness direction De is less than or equal to the dimension of the other hollow complex acoustic elements 110 in the thickness direction De. In particular, the male and female connection elements do not pass through the surface formed by the bottom or edge of the hollow complex acoustic element. The male and female connection elements exist in the volume between the surface defined by the bottom or edge of the hollow complex acoustic element and the surface defined by the apex of the hollow complex acoustic element.

[0074] Preferably, if Figure 2 and 3 As shown, all male connection elements 121 of the annular sector 100 are located on the second assembly edge 102a and all female connection elements 122 of the annular sector 100 are located on the first assembly edge 101a, so as to facilitate the preparation of the annular sector 100 and its assembly with adjacent sectors of a multi-element acoustic component.

[0075] However, it is not beyond the scope of the invention when the first assembly edge comprises male and female connection elements, in which case the second assembly edge also has female connection elements where the first edge of the second row comprises male connection elements, and has male connection elements where the first edge of the second row comprises female connection elements.

[0076] Preferably, one second row of hollow acoustic elements 110 is not adjacent to another second row of hollow acoustic elements 110 in order to improve assembly between annular sectors of the annular multi-element acoustic component 10. Thus, two second rows of hollow acoustic elements 110 of annular sectors 100 are preferably separated by one or more first rows of hollow acoustic elements 11.

[0077] In the case of square-based hollow acoustic elements, the squares formed by the hollow acoustic elements are arranged side by side, with each side of the square being oriented in the assembly circumferential direction Dc or in the axial direction Da. Therefore, the length Lc of the annular sector 100 of the multi-element acoustic component 10 is understood to be the length extending in the assembly circumferential direction Dc between the outside of the first row of square hollow acoustic elements belonging to the first assembly edge and the outside of the same first row of square hollow acoustic elements belonging to the second assembly edge.

[0078] In the case of circular hollow acoustic elements, the centers of the circles formed by the same row of hollow acoustic elements are aligned along the assembly circumferential direction Dc. Thus, the length Lc of the annular sector 100 of the multi-element acoustic component 10 is understood to be the length extending along the circumferential direction Dc between the outside of the first row of circular hollow acoustic elements belonging to the first assembly edge and the outside of the same first row of circular hollow acoustic elements belonging to the second assembly edge, which length passes through the center of the first row of circular hollow acoustic elements. Furthermore, the centers of the circles of at least one of the two alternating rows of circular hollow acoustic elements are aligned along the axial direction Da.

[0079] In the case of a hexagonal hollow acoustic element, as Figures 2 to 9 In the example shown, the hexagons formed by the hollow acoustic elements 110 are arranged side by side, and the centers of the hexagons of the same row of hollow acoustic elements 110 are aligned along the assembly circumferential direction Dc. Therefore, the length Lc of the annular sector 100 of the multi-element acoustic component 10 should be understood as the length extending along the assembly circumferential direction Dc between the outer side of the first row of hexagonal hollow acoustic elements 110 belonging to the first assembly edge 101a extending along the axial direction Da and the outer side of the same first row of hexagonal hollow acoustic elements 110 belonging to the second assembly edge 102a extending along the axial direction Da, which length passes through the center of the first row of hexagonal hollow acoustic elements 110. In addition, the centers of the hexagons of at least one of the two alternating rows of hollow acoustic elements 110 are aligned along the axial direction Da.

[0080] The assembly of the annular sectors 100 of the multi-element acoustic component along the assembly circumferential direction Dc enables the preparation of the multi-element acoustic component 10. Preferably, all the annular sectors 100 of the multi-element acoustic component are identical to facilitate the manufacture and assembly of said multi-element acoustic component 10.

[0081] By using the same annular sector 100 for a multi-element acoustic component and having the same number of hollow acoustic elements 110 in each first row and one less hollow acoustic element 110 in each second row containing connecting elements 121 and 122, it is ensured that the assembly edges 101a and 102a of the annular sector 100 will be complementary.

[0082] This complementary property applies even if the rows of hollow complex acoustic elements are irregularly offset relative to each other, e.g. Figure 6 , which illustrates a multi-element acoustic component 10b comprising a plurality of annular sectors 100b containing hollow complex acoustic elements 110b. Figure 6 In the example shown, the assembly edges of the annular sectors 100 b are indeed complementary at their connection.

[0083] In order to limit the occurrence of gaps or overlaps between the annular sectors 100 of the multi-element acoustic component 10, the annular sectors 100 may be arranged according to Figure 7 and 8 The design is carried out according to the design method of the present invention shown.

[0084] The multi-element acoustic component 10 is disposed in contact with the polyhedral body 20. Therefore, the perimeter P of the upper surface of the multi-element acoustic component 10 is 10 The perimeter P of the upper surface of the multicellular body 20 must be equal to the perimeter P of the upper surface of the multicellular body 20 in each plane perpendicular to the axial direction Da. 20The perimeter P of the upper surface of the multi-element acoustic component 10 is φ 100, which corresponds to the annular sectors 100 to avoid gaps or overlaps between the annular sectors 100. 10 The sum of the lengths Lc of each sector 100 of the multi-element acoustic component 10. The perimeter P of the upper surface of the multicellular body 20 20 In a well-known manner, the thickness e of the polyhedral body 20 in the thickness direction De is determined according to the perimeter of the surface to be covered of the component 5 and the desired thickness e of the polyhedral body 20 in the thickness direction De. 20 Sure.

[0085] In the example shown here, the sectors 100 of the multi-element acoustic component 10 are identical and all have the same length Lc along the assembly circumferential direction Dc.

[0086] A first step 1000 of designing a multi-element acoustic component 10 makes it possible to determine the number N of annular sectors 100 that will constitute said multi-element acoustic component 10 .

[0087] The maximum achievable length Lcmax of annular sector 100 of multi-element acoustic component 10 along assembly circumferential direction Dc is limited and depends on the manufacturing method used to manufacture said annular sector 100. Annular sector 100 can be manufactured in a well-known manner by injection molding or stamping, preferably under controlled temperature and pressure.

[0088] Therefore, the length Lc of the annular sector 100 is less than or equal to the maximum achievable length Lcmax given by the manufacturing means. However, in order to limit the number N of annular sectors 100 to be assembled and to reduce the number of connecting elements 121 and 122 required, it is desirable that the length Lc of the annular sector 100 is as close as possible to the maximum achievable length Lcmax.

[0089] As a result, the number N of sectors 100 of the multi-element acoustic component 10 is determined by rounding off the ratio of the perimeter P10 of the upper surface of the multi-element acoustic component 10 to be prepared to the maximum achievable length Lcmax of the annular sector given by the manufacturing means to the next integer. 10 The perimeter P corresponding to the upper surface of the polyhedron 20 20 .

[0090] For example, if the surface of the component 5 to be covered is a cylindrical surface of revolution with a radius R5 = 1500 mm, and the desired thickness e of the polyhedral body 20 is 20 The perimeter P of the upper surface of the multicellular body 20 is 28.6 mm. 20 will be approximately 9600 mm. Therefore, the perimeter P of the upper surface of the multi-element acoustic component 10 to be prepared is 10It will be approximately 9600 mm. It is also considered that the maximum achievable length Lcmax of an annular sector is 1000 mm. It follows that the number N of sectors 100 of the multi-element acoustic component 10 is equal to ten.

[0091] Here and below with Figure 7 The numerical values ​​given in the description are only for example, so as to better understand the advantages of the design method of the present invention. They should not be regarded as limiting the present invention.

[0092] According to the second step 2000 of designing the annular acoustic structure 10, the length Lc of each of the N annular sectors 100 is determined by dividing the perimeter P of the upper surface of the multi-element acoustic component 10 to be produced by 10 It is determined by dividing by the number N of sectors 100. In our example, this results in a length Lc equal to 960 millimeters.

[0093] The third step 3000 of designing the multi-element acoustic component 10 enables the determination of the theoretical width lc0 of each hollow complex acoustic element along the assembly circumferential direction Dc. This theoretical width lc0 corresponds to a theoretical width that allows optimal attenuation of the sound waves to be attenuated, in particular for a given frequency range. This theoretical width lc0 can be determined by acoustic studies performed independently of the method described herein.

[0094] The theoretical width lc0 of the hollow acoustic element corresponds to the distance extending from the middle of the edge separating the hollow acoustic element from the first adjacent hollow acoustic element in the same row to the middle of the edge separating the hollow acoustic element from the second adjacent hollow acoustic element in the same row along the assembly circumferential direction Dc.

[0095] In our example, the theoretical width lc0 of the hollow acoustic element 110 along the assembly circumferential direction Dc is estimated to be 20 mm.

[0096] The third step 3000 may be performed independently of the first step 1000 and the second step 2000. For example, the first step 1000 and the second step 2000 may be performed in parallel with the third step 3000.

[0097] The fourth step 4000 of designing the multi-element acoustic component 10 makes it possible to determine an integer number n of hollow acoustic elements 110 per first row per annular sector 100. This number n is obtained by rounding the ratio of the length Lc of the circumferential edges 101c and 102c to the theoretical width lc0 of the hollow acoustic element 110 to the nearest unit.

[0098] In our example, each annular sector 100 has a length Lc of 960 meters and a theoretical width lc0 estimated at 18 mm. Thus, a number n of 53 hollow complex acoustic elements 110 is obtained in each first row, or a number n of 52 hollow complex acoustic elements 110 is obtained in each second row containing male and female connection elements 121 and 122.

[0099] like Figure 8 As shown, it can be seen that at the end of the fourth step 4000, the length of the set of n hollow complex acoustic elements 110 in the first row can be different from the length Lc of the circumferential edges 101c and 102c. In our example, it can be seen that there is about 6 mm of lost space 111, as shown in FIG. Figure 8 shown.

[0100] In our example, 53 hollow complex acoustic elements 110 have a theoretical width lc0 of 18 mm. Therefore, the set of n hollow complex acoustic elements 110 of the first row has a length of 954 mm, i.e. 6 mm different from the length Lc of 960 mm. On the scale of a multi-element acoustic component 10 comprising ten annular sectors 100, these ten approximately 6 mm residual spaces 111 represent a total of approximately 60 mm of residual space in the circumferential direction Dc.

[0101] The design method proposed by the present invention aims to reduce this residual space, in order to increase the functional surface of the annular acoustic structure 1 and to enable easier and cheaper assembly of the multi-element acoustic component 10 .

[0102] Therefore, the fifth step 5000 of designing the multi-element acoustic component 10 enables the final width lc of the hollow complex acoustic element 110 along the assembly circumferential direction Dc to be determined.

[0103] This final width lc is obtained by dividing the length Lc of the circumferential edges 101c and 102c by the number n of hollow complex acoustic elements 110 per first row of sector 100 .

[0104] Final width l of the hollow acoustic element c0 Corresponds to the distance extending from the middle of the edge separating the hollow acoustic element from the first adjacent hollow acoustic element in the same row to the middle of the edge separating the hollow acoustic element from the second adjacent hollow acoustic element in the same row in the assembly circumferential direction Dc.

[0105] In our example, each annular sector 100 has a length Lc of 960 mm and in the first row there are a number n of 53 hollow complex acoustic elements 110. Therefore, the final width lc of the hollow acoustic element 110 will be 18.1 mm, i.e., with respect to the theoretical width l c0Increased by 0.1 mm. The theoretical width l of the hollow complex acoustic element 110 c0 The width difference between the final width lc is not sufficient to cause a significant reduction in the acoustic performance of the acoustic structure 1. In return, this difference allows a significant improvement in the assembly of the multi-element acoustic component 10 and in the area and continuity of the functional surfaces of the acoustic structure 1.

[0106] By using the above-described design method, identical annular sectors 100 are produced, allowing a very satisfactory assembly of the multi-element acoustic component 10 in a polyhedron 20 around the component 5. The design of identical annular sectors facilitates its manufacture and reduces the associated design and manufacturing costs.

[0107] The design and preparation of the polyhedron 20 is less restricted than the design and manufacture of the multi-element acoustic component 10. Therefore, it is preferred to first design the multi-element acoustic component 10, which then enables the number and size of the cells 210 of the polyhedron 20 to be determined so that each hollow complex acoustic element 110 and each female connecting element 122 corresponds to a cell 210 of the polyhedron 20.

[0108] Preferably, the multicellular bodies 20 are also assembled in sectors 200 on the surface to be covered of the component 5, such as Figure 8 As shown. Since the manufacturing restrictions of the polyhedron 20 are less, it is preferred to manufacture large polyhedron sectors 200 so as to use a limited number of sectors 200 of the polyhedron 20. Therefore, preferably, the length of the annular sector 200 of the polyhedron 20 along the assembly circumferential direction Dc is greater than the length Lc of the annular sector 100 of the multi-element acoustic component 10.

[0109] When the design of the acoustic structure 1 is completed, the acoustic structure 1 can be prepared.

[0110] The baffle array 220 of the multicell 20 and the sector 100 of the multi-element acoustic component 10 can be prepared by injection of filled or unfilled thermoplastic or thermosetting materials, by injection compression of filled or unfilled thermoplastic or thermosetting materials, or by injection of filled or unfilled thermoplastic or thermosetting materials by controlling the mold temperature. The acoustic skin 30 can be produced by manual or automatic layup of a composite material having a thermoplastic or thermosetting matrix.

[0111] Thermoplastic materials for preparing the baffle array 220 of the sector 100 or the multicell 20 of the multi-element acoustic component 10 may be selected from the following materials, in particular but not limited to: polyaryletherketone (PAEK), such as polyetheretherketone (PEEK) and polyetherketoneketone (PEKK), polyetherimide (PEI), polycarbonate (PC), polyphenylene sulfide (PPS) and polysulfone (PSU). The thermoplastic material may be filled or unfilled.

[0112] The partition array 220 of the multicellular body 20 can also be made of, for example, aluminum or It is obtained by making a honeycomb structure.

[0113] The sectors 100 of the multi-element acoustic component 10 or the baffle arrays 220 of the polyhedron 20 can be manufactured by direct bending in the assembly circumferential direction Dc, or can be bent after manufacturing, for example by hand or by performing a thermoforming operation. Thin complex acoustic elements are more easily deformed than thick acoustic elements.

[0114] Still in the example described here, the multi-element acoustic component 10 sector 100 can be assembled with the polyhedron 20 by bonding or welding. The assembly between the sector 100 of the multi-element acoustic component 10 and the polyhedron 20 is greatly facilitated by the self-positioning of the complex acoustic element 110 and the baffle 220 of the polyhedron 20.

[0115] The acoustic skin 30 may be fixed to the upper portion of the bottom of the complex acoustic element 110 by bonding or welding.

[0116] Once assembled, the acoustic structure 1 comprises a plurality of complete acoustic units, each of which is formed by a complex acoustic element 110 and a baffle 220 of a polyhedral body 20 surrounding it, such as Fig. 9 shown.

[0117] The height H of the complex acoustic element 110 110 is smaller than the height H of the unit cell 210 of the polyhedron 20 210 More precisely, the height H of the hollow acoustic element 110 is 110 In the thickness direction De, the height H between the unit 210 210 Between 10% and 99%. 110 The diameter E of each hollow acoustic element 110 may be between 5 mm and 100 mm, and the bottom of each hollow acoustic element 110 may be inscribed in a circle with a diameter between 5 mm and 50 mm. In addition, the hollow complex acoustic element 110 has a very small thickness E 110 , less than 1 mm, usually between 0.3 mm and 0.5 mm.

[0118] Of course, if the elements constituting the annular acoustic structure 1 are manufactured according to different processes or with different materials, it does not go beyond the scope of the present invention.

[0119] Figures 1 to 9 The annular acoustic structures, multi-element acoustic components and their sectors and polytopes shown in are simplified, and the number of cells or hollow acoustic elements per row or sector may be varied or reduced for the sake of simplifying the figures.

[0120] The expression “between” should be understood as including the boundaries.

Claims

1. An annular sector (100) of an annular multi-element acoustic component (10), which extends along an assembly direction (Dc) between a first assembly edge (101a) and a second assembly edge (102a) opposite the first assembly edge (101a), the sector (100) comprising a plurality of rows of hollow complex acoustic elements (110), each of the hollow complex acoustic elements having a shape that gradually narrows between a base and a vertex, the hollow complex elements (110) being interconnected by one or more adjacent edges, each row extending along the assembly direction (Dc) from the first assembly edge (101a) to the second assembly edge (102a), the sector (100) is characterized in that it includes a plurality of first rows and one or more second rows, the first rows containing the same number of hollow complex acoustic elements (110), the second rows containing one less hollow complex acoustic element (110) than the first rows, each second row also including a male connecting element (121) on one of the assembly edges (102a) and a female connecting element (122) on the other assembly edge (101a), the female connecting element (122) having the same size as the hollow complex acoustic element (110) along the assembly direction (Dc).

2. An annular sector (100) of a multi-element acoustic component (10) according to claim 1, wherein: The male connection element (121) has a perforated shape that gradually narrows between the base and the apex.

3. An annular sector (100) of a multi-element acoustic component (10) according to claim 1 or 2, wherein: The bottom of the hollow complex acoustic element (110) is hexagonal.

4. An annular multi-element acoustic component (10), comprising assembling a plurality of annular sectors (100) according to any one of claims 1 to 3 along an assembly direction (Dc), each male connecting element (121) of an annular sector (100) of the acoustic component (10) being inserted into a female connecting element (122) of an adjacent sector.

5. The multi-element acoustic component (10) according to claim 4, wherein: All sectors (100) are identical.

6. An annular acoustic attenuation structure (1), comprising an annular multi-element acoustic component (10) according to claim 4 or 5 and an annular polyhedron (20), wherein the vertex of each hollow complex acoustic element (110) of the multi-element acoustic component (10) is inserted into a unit (210) of the polyhedron (20).

7. The annular acoustic attenuation structure (1) according to claim 6, further comprising a perforated acoustic skin (30), wherein the acoustic skin (30) is in contact with the bottom of the hollow complex acoustic element (110).

8. The annular acoustic attenuation structure according to claim 6 or 7, wherein: The annular polyhedron (20) comprises a plurality of annular sectors (200) of the polyhedron (20) assembled along an assembly direction (Dc), wherein the length of the annular sectors (200) of the polyhedron (20) along the assembly direction (Dc) is greater than the length of the annular sectors (100) of the multi-element acoustic component (10).

9. A method for designing an annular multi-element acoustic component (10) according to claim 5, the annular multi-element acoustic component (10) extending around an axial direction (Da) and having a defined inner or outer cross-sectional perimeter (P 10 ), each annular sector (100) of the acoustic component (10) extends in an axial direction (Da) between a first circumferential edge (101c) and a second circumferential edge (102c), the circumferential edges (101c, 102c) extending in an assembly direction (Dc), the method comprising the following steps: By dividing the cross-sectional perimeter (P 10 ) to the maximum theoretical length (Lcmax) of the annular sector (100) of the multi-element acoustic component (10), rounded to the next integer to determine the number (N) of the annular sectors (100) of the multi-element acoustic component (10); Determining the length (Lc) of the circumferential edge (101c, 102c) of each annular sector (100) of the acoustic component (10); Determine the theoretical width (l) of the hollow complex acoustic element (110) along the assembly direction (Dc) corresponding to the required acoustic attenuation c0 ); determining an integer number (n) of each first row of hollow complex acoustic elements (110) of each annular sector (100); A final width (lc) of the hollow complex acoustic element (110) along an assembly direction (Dc) is determined.

10. A method for manufacturing an annular acoustic attenuation structure (1), comprising: Designing an annular multi-element acoustic component (10) according to claim 9; preparing an annular sector (100) of the multi-element acoustic component (10) according to the design; Assembling the annular sectors (100) of the multi-element acoustic component (10) with each other and with the annular polyhedron (20) such that each hollow complex acoustic element (110) is arranged in a cell (210) of the polyhedron (20); A multi-element acoustic component (10) is covered with an acoustic skin (30) to form an annular acoustic attenuation structure (1) comprising at least an annular multi-element acoustic component (10), an annular multicellular body (20) and an acoustic skin (30).

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