Patent Publication Number: US-2022212809-A1

Title: Air intake lip of a turbomachine nacelle comprising an acoustic device and method for producing such a lip

Description:
TECHNICAL FIELD 
     The present invention relates to the field of aircraft turbomachines and is more particularly directed to an air intake lip of an aircraft turbomachine nacelle. 
     In a known manner, an aircraft comprises one or more turbomachines to allow its propulsion by acceleration of an air flow that circulates from upstream to downstream in the turbomachine. 
     With reference to  FIG. 1 , there is represented a turbomachine  100  extending along an axis X and comprising a fan  110  rotatably mounted about axis X in a nacelle comprising an internal shell  112  in order to accelerate an air flow F from upstream to downstream. Hereinafter, the terms upstream and downstream are defined with respect to the circulation of the air flow F. The turbomachine  100  comprises at its upstream end an air intake  102  that allows the incoming air flow F to be separated into an internal air flow FINT that is accelerated by the fan  110  and an external air flow FEXT that is guided externally to the nacelle. 
     With reference to  FIG. 1 , the air intake  102  comprises an upstream portion  102   a , known to the person skilled in the art as a lip  102   a , and a downstream portion  102   b . In this example, the lip  102   a  is separated from the downstream portion  102   b  by an inner partition wall  125 . 
     The lip  102   a  comprises an internal wall  121  pointing to axis X and an external wall  122  that is opposite to the internal wall  121 , the walls  121 ,  122  are connected through an upstream wall  123  so as to form an annular cavity  120 . Thus, the lip  102   a  enables the incoming air flow F to be separated into an internal air flow FINT guided by the internal wall  121  and an external air flow FEXT guided by the external wall  122 . Hereinafter, the terms internal and external are defined radially with respect to axis X of the turbomachine  100 . 
     The air circulation on the internal wall  121  of the lip  102   a  generates acoustic nuisance and it was proposed to equip the lip  102   a  with an annular acoustic device to limit this nuisance. 
     With reference to  FIG. 2 , a lip  102   a  equipped with an acoustic device  104  is known from patent application WO1216/005711. The acoustic device  104  comprises a rear skin  142  to which an acoustic, in particular, honeycomb material  140 , is attached. In practice, the rear skin  142  is attached to the acoustic material  140  by soldering. The acoustic device  104  is positioned in the annular cavity  120  on the inner surface of the internal wall  121  of the lip  102   a.    
     To integrate such an acoustic device  104 , it is necessary to attach the rear skin  142  to the inner surface of the internal wall  121  and to form holes (not represented) in the internal wall  121  so as to allow circulation of the internal air flow FINT through the acoustic device  104  in order to limit acoustic nuisance. 
     In practice, attaching the rear skin  142  of the acoustic device  104  to the inner surface of the internal wall  121  of the lip  102   a  is performed by soldering using a 6061 type alloy that is compatible with the internal wall  121 , which is generally made of aluminum to withstand de-icing temperatures. 
     Such a soldering step reduces mechanical characteristics of the internal wall  121 . Also, it is necessary to increase its thickness to allow a good mechanical strength, thereby increasing the mass of the lip  102   a . In fact, geometric tolerances in manufacturing the acoustic device  104  and the lip  102   a  make the assembly complex. Furthermore, during cooling following soldering, the internal wall  121  is susceptible to deformation. Furthermore, during soldering, the lip  102   a  should be placed in a soldering oven which is likely to cause the external wall  122  to collapse during heating. In addition, it is necessary to provide specific and complex tooling to hold the acoustic device  104  and the lip  102   a  together during soldering. Finally, machining of the acoustic holes in the internal wall  121  is complex because they should be precisely aligned with cells in the acoustic material  140  to ensure optimal acoustic treatment. 
     One of the objectives of the invention is to facilitate manufacture of an air intake lip comprising an annular acoustic device while having a reduced manufacturing cost. 
     Still with reference to  FIG. 2 , it is known to equip a lip  102   a  with a de-icing system in order to avoid accumulation of ice on the internal wall  121 . For this purpose, it has been proposed to provide a hot air injector  103  in the annular cavity  120  and to form blow-out openings  130  in the internal wall  121 , preferably, upstream of the acoustic device  104  in order to heat the internal wall  121 . Machining such blow-out openings  130  is time consuming and complex to perform. 
     Another objective of the invention is to facilitate manufacture of an air intake lip comprising such blow-out openings. 
     Incidentally, an aircraft nacelle comprising an air intake, comprising an acoustic device, and a downstream body comprising another acoustic device is known in prior art from patent application FR2924409. Patent application FR2924409 does not set forth any solution for manufacturing an air intake but only deals with the assembly to a downstream body of a nacelle. 
     US2012048389A1 and US2012241249A1 teach an air intake comprising an acoustic attenuation member located downstream of the air intake lip, that is, outside the annular cavity. US2002139899A1 teaches an air intake lip without blow-out openings. 
     SUMMARY 
     The invention relates to an air intake lip of an aircraft turbomachine nacelle extending along an axis X in which an air flow circulates from upstream to downstream, the lip annularly extending about axis X and comprising an internal wall pointing to axis X and an external wall which is opposite to the internal wall, the internal wall and the external wall being connected through an upstream wall, the lip comprising an annular acoustic device mounted in the annular cavity. 
     The invention is remarkable in that the lip comprises:
         a first module, comprising the external wall, the upstream wall and a front wall forming an upstream portion of the internal wall and   a second module, comprising the acoustic device and a front skin forming a downstream portion of the internal wall, the first module and the second module being secured together so that the front wall and the front skin together form the internal wall of the lip.       

     According to the invention, the lip comprises two insert modules that are assembled together. Such a modular design makes it easier to hold and process the modules since their overall size is limited and can be achieved with simpler and less expensive equipment. Furthermore, the risk of defects is limited because it is easier to check the modules, which are accessible on both faces. A modular assembly allows the use of various assembly solutions without affecting health of the modules. In addition, mechanical characteristics of the internal wall are preserved and it is no longer susceptible to deformation. The external wall is also preserved. Finally, the second acoustic module can simply be replaced in case of a defect. 
     Preferably, the front skin comprises acoustic perforations. Advantageously, this allows the internal air flow to penetrate the acoustic device. 
     Preferably, the second module comprises a rear skin, with the acoustic device being housed between the front skin and the rear skin. The acoustic device is thus radially sandwiched. 
     Preferably, the front wall of the first module is radially internal to the front skin of the second module at an interface zone between the front wall and the front skin. This advantageously allows for a radial connection in the superimposition zone. 
     According to one aspect, the lip comprises at least one blow-out opening formed in the internal wall of the lip. Such a blow-out opening allows for de-icing of the internal wall of the lip. 
     Preferably, the blow-out opening is positioned upstream of the acoustic device to allow for de-icing of the front skin during circulation of the internal air flow. 
     Preferably, the lip comprises at least one blow-out opening formed at the interface between the front wall of the first module and the front skin of the second module. Such a blow-out opening advantageously avoids machining the front wall, thereby improving its mechanical strength. The blow-out opening is formed at the interface during assembly. 
     Even more preferably, the front wall of the first module is radially spaced from the front skin of the second module so as to form at least one blow-out opening between them. The blow-out opening advantageously comprises a guide channel for precisely guiding the hot de-icing air flow. 
     Preferably, the lip comprises a filling member housed between the front wall of the first module and the front skin of the second module, that is, in the guide channel of the blow-out opening. 
     Preferably, the front wall of the first module is radially spaced from the front skin of the second module by at least one spacer stud. Such a spacer stud is used to define the radial thickness of the blow-out opening. Preferably, the spacer stud has an aerodynamic shape so as to guide an air flow into the blow-out opening. 
     According to a preferred aspect, the spacer stud comprises an opening for guiding a mechanical connection member configured to secure the front wall of the first module to the front skin of the second module. Preferably, the spacer stud has an aerodynamic profile so as to guide the de-icing air flow in an optimal manner. It especially prevents the occurrence of turbulence due to the mechanical connection members. 
     According to one aspect, the lip comprises at least one inner partition wall mounted between the first module and the second module in the annular cavity, preferably between the inner surface of the external wall of the first module and the inner surface of the rear skin of the second module. Mounting such an inner partition wall is facilitated. 
     According to one aspect, the annular cavity comprises at least one injector of a hot air flow in order to allow de-icing by blowing through the blow-out opening. 
     The invention also relates to an aircraft air intake comprising a lip as previously set forth. Preferably, the air intake comprises an upstream portion, formed by the lip, and a downstream portion to which the lip is mounted. 
     The invention also relates to an aircraft turbomachine comprising a nacelle comprising an air intake as previously set forth. 
     The invention also relates to a method for manufacturing an air intake lip, as previously set forth, comprising a step of manufacturing the first module and the second module independently and a step of securing the first module to the second module so that the front wall and the front skin together form the internal wall of the lip. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention will be better understood upon reading the following description, which is given solely by way of example, and refers to the appended drawings given as non-limiting examples, in which identical references are given to similar objects and in which: 
         FIG. 1  is a schematic representation in a longitudinal cross-section view of a turbomachine comprising a nacelle with an air intake; 
         FIG. 2  is a schematic representation in a longitudinal cross-section view of an air intake comprising an acoustic device according to prior art; 
         FIG. 3  is a schematic representation in a longitudinal cross-section view of a step of manufacturing an air intake according to prior art; 
         FIG. 4  is a schematic representation in a longitudinal cross-section view of a lip comprising a first main module and a second acoustic module assembled together; 
         FIG. 5  is a schematic representation of the second acoustic module for a lip according to the invention; 
         FIG. 6  is a schematic perspective representation of a lip according to the invention with an inner partition wall; 
         FIGS. 7A and 7B  are schematic representations in a longitudinal cross-section view and a partial perspective view of a first embodiment of an assembly of a lip comprising blow-out openings; 
         FIGS. 8A and 8B  are schematic longitudinal section and partial perspective representations of a second embodiment of an assembly of a lip comprising blow-out openings; 
         FIG. 8C  is a schematic representation in a longitudinal cross-section view of a downstream end of the first main module according to one aspect of the invention; 
         FIG. 9  is a schematic representation in a longitudinal cross-section view of a third embodiment of an assembly of a lip comprising blow-out openings; 
         FIG. 10  is a schematic perspective representation of an assembly of a lip comprising blow-out openings and a filling member; 
         FIGS. 11A and 11B  are partial schematic perspective representations of an assembly of a lip comprising blow-out openings and contoured spacer studs. 
     
    
    
     It should be noted that the figures set out the invention in detail for implementing the invention, said figures of course being able to serve to better define the invention where appropriate. 
     DETAILED DESCRIPTION 
     With reference to  FIG. 4 , an air intake  2  of an aircraft turbomachine nacelle according to an embodiment of the invention, in particular, a turbojet engine nacelle is represented. The turbomachine extends along an axis X and allows circulation, during a thrust, of an air flow from upstream to downstream. Hereafter, axis X is oriented from upstream to downstream. With reference to  FIG. 6 , the air intake  2  comprises an upstream portion  2   a , known to the person skilled in the art as lip  2   a , and a downstream portion  2   b . In this example, the lip  2   a  is separated from the downstream portion  2   b  by an inner partition wall  25 . 
     The lip  2   a  annularly extends about axis X and comprises an internal wall  21  pointing to axis X and an external wall  22  that is opposite to the internal wall  21 . The walls  21 ,  22  are connected through an upstream wall  23  so as to delimit an annular cavity  20 . Thus, the lip  2   a  enables the incoming air flow to be separated into an internal air flow guided by the internal wall  21  and an external air flow guided by the external wall  22 . Hereafter, the terms internal and external are defined radially with respect to axis X of the turbomachine. The lip  2   a  comprises an annular acoustic device  50  mounted in the annular cavity  20 . 
     According to the invention, the lip  2   a  comprises a first module M 1 , comprising the external wall  22 , the upstream wall  23  and a front wall  24  that forms an upstream portion of the internal wall  21 . The lip  2   a  further comprises a second module M 2 , comprising the acoustic device  50  and a front skin  51  that forms a downstream portion of the internal wall  21 , the first module M 1  and the second module M 2  being secured together so that the front wall  24  and the front skin  51  together form the internal wall  21  of the lip  2   a . Preferably, the internal wall  21  has an aerodynamic shape to optimally guide the air flow in the secondary stream of the turbomachine. 
     In other words, contrary to prior art which taught to make a one-piece internal wall  21 , a modular internal wall  21  which comprises a front wall  24 , forming an upstream portion, and a front skin  51 , forming a downstream portion, which are secured during assembly, is set forth. As will be set forth later, such a modular design allows a second acoustic module M 2  to be formed independently, thereby facilitating the manufacture thereof and limiting the risk of defects during assembly. 
     As illustrated in  FIG. 4 , the first module M 1 , also referred to as the main module M 1 , has a structure similar to prior art except that it does not have a long internal wall but only a shortened internal wall called a front wall  24 . Preferably, the main module M 1  is made of a metallic material, preferably, resistant to high temperatures, for example, of aluminum. Several embodiments of a main module M 1  will be set forth below. The first module M 1  is preferably as one-piece. 
     In this embodiment, the first module M 1  is made by forming (explosively or otherwise) or by flow forming. 
     As illustrated in  FIG. 4 , the second module M 2 , also referred to as the acoustic module M 2 , has an acoustic device  50  which is, in this example, in the form of a honeycomb structure. The acoustic device  50  comprises a plurality of acoustic, preferably metallic, cells. Nevertheless, it goes without saying that the acoustic device  50  could be in other forms. 
     With reference to  FIGS. 4 and 5 , the second module M 2  comprises a front skin  51  and a rear skin  52  between which the acoustic device  50  is mounted. The front skin  51  of the second acoustic module M 2  is configured to extend as an extension of the front wall  24  of the first module M 1 . The front skin  51  is preferably made of a metallic material, especially, of aluminum. 
     The front skin  51  comprises a plurality of perforations so as to put the acoustic device  50  in communication with the air flow circulating inside the lip  2   a . The perforations may be made before or after assembly of the second module M 2 . Similarly, the perforations may be made before or after assembly of modules M 1 , M 2 . 
     The rear skin  52  defines a concavity in which the acoustic device  50  is housed. The rear skin  52  is preferably made of a metallic material, especially of aluminum. The acoustic device  50  is secured, preferably by soldering, to the rear skin  52 . 
     As illustrated in  FIG. 5 , in a longitudinal cross-section view, the rear skin  52  comprises a concave central portion  52   b  and two end portions  52   a  that are secured to the front skin  51 . Such securing is simple to implement since it is carried out independently of the first module M 1 . Preferably, the rear skin  52  is secured to the front skin  51  by soldering, welding or the like or by mechanical assembly. Advantageously, the second module M 2  has a reduced overall size thereby facilitating its soldering and assembly in an oven. Moreover, upon manufacturing the second module M 2 , mechanical properties of the first module M 1  are advantageously not affected. 
     Preferably, the ends  51   a  of the front skin  51  are longer than those of the rear skin  52  so as to be secured to the first module M 1  as will be set forth hereafter. 
     After assembly, the second module M 2  can be stored, handled and used independently of the first module M 1 , which significantly simplifies logistics and assembly of the lip  2   a.    
     Advantageously, the first module M 1  and the second module M 2  can be obtained by different methods. 
     Advantageously, the modules M 1 , M 2  are manufactured independently and then assembled together. The assembly is preferably performed mechanically, by welding (laser, friction, electron beam, etc.) or the like. 
     With reference to  FIG. 6 , according to one aspect of the invention, the air intake  2  comprises an inner partition wall  25  so as to form a closed annular cavity  20  in which a de-icing air flow can especially circulate. In this example, the inner partition wall  25  is mounted between the external wall  22  of the first module M 1  and the rear skin  52  of the second module M 2 . Such a design is advantageous since it allows, on the one hand, to maximize the dimensions of the acoustic device  50  and, on the other hand, to facilitate mounting of the inner partition wall  25  which can be previously mounted to the first module M 1  or to the second module M 2 . Nevertheless, it goes without saying that the acoustic device  50  could be independent of the inner partition wall  25  and spaced from the latter, in particular, the inner partition wall  25  could be located downstream of the acoustic device  50 . 
     In this example, the assembly of an inner partition wall  25  in the air intake  2  has been set forth. Such an inner partition wall  25  is not required and may be omitted depending on the configurations of the air intake  2 . Hereinafter, for the sake of clarity and brevity, such an inner partition wall  25  is not represented, but of course could be provided. 
     As previously indicated, the air intake  2  comprises an upstream portion  2   a  and a downstream portion  2   b . Following its manufacture, the lip  2   a  may be mounted to a downstream portion  2   b  to form the air intake  2 . Preferably, the downstream portion  2   b  comprises an acoustic device. According to one aspect of the invention, the acoustic device of the downstream part  2   b  is independent of the acoustic device  50  of the lip  2   a . According to another aspect of the invention, the acoustic device continuously extends between the downstream portion  2   b  and the lip  2   a  to provide optimal acoustic attenuation. An inner partition wall  25  between the lip  2   a  and the downstream portion  2   b  of the air intake  2  has been set forth but is optional. 
     According to one aspect of the invention, the annular cavity  20  comprises at least one injector of a hot air flow, in particular, for de-icing the lip  2   a . According to one aspect of the invention, the lip  2   a  comprises at least one blow-out opening in the internal wall  21 , preferably a plurality of blow-out openings in order to guide the hot air flow out of the annular cavity  20  and thereby de-ice the internal wall  21 . 
     Several embodiments of blow-out openings will now be set forth with reference to  FIGS. 7A through 11B . 
     As illustrated in  FIGS. 7A and 7B , according to a first embodiment, the first module M 1  and the second module M 2  are secured together at an interface zone in which one end  51   a  of the front skin  51  of the second module M 2  is secured to the front wall  24  of the first module M 1 . Preferably, in the interface zone, the front skin  51  is radially internal to the front wall  24  of the first module M 1  so as to allow securing in a radial direction, for example, by welding or mechanical connection. In this embodiment, three connections L are represented in  FIG. 7B . 
     In order to form a lip  2   a  having an internal wall  21  having an aerodynamic curvature, the front skin  51  of the second module M 2  is curved so as to comprise an end portion  51   a  superimposed to the front wall  24  of the first module M 1  to allow attachment and a central portion  51   b  as an extension of the front wall  24  of the first module M 1  as illustrated in  FIG. 7A . 
     Preferably, as illustrated in  FIG. 7A , the downstream end  24   a  of the front wall  24  is beveled so as to snugly fit the curvature of the front skin  51  of the second module M 2 , with its radially external surface converging radially inwardly along an upstream-downstream direction. Such a bevel is simple to make and avoids a significant deformation of the front skin  51  in order to keep an aerodynamic profile. The bevel thus faces a curvature of the front skin  51  to obtain a continuous internal wall  21 . 
     As illustrated in  FIGS. 7A and 7B , the front wall  24  of the first module M 1  comprises a plurality of blow-out openings  31  that are formed away from the downstream end of the front wall  24 . In this example, the blow-out openings  31  extend substantially radially into the material of the front wall  24 . Such an independent blow-out opening  31  is known to the skilled person as “separated slot”. With reference to  FIG. 7B , each blow-out opening  31  is in this example in the form of an azimuthally directed slot. Of course, the shape and direction could be different. 
     The blow-out openings  31  are formed in the first module M 1  independently of the second module M 2 . With reference to  FIG. 7A , the blow-out openings  31  are formed in an extra thickness of the front wall  24 , such an extra thickness is nevertheless not necessary. 
     According to a second embodiment, as illustrated in  FIGS. 8A and 8B , the first module M 1  and the second module M 2  are secured together at an interface zone in which the end  51   a  of the front skin  51  of the second module M 2  is secured to the front wall  24  of the first module M 1 . Preferably, in the interface zone, the front skin  51  is radially internal to the front wall  24  of the first module M 1  so as to allow securing along a radial direction. 
     In this second embodiment, the front wall  24  and the front skin  51  are spaced apart radially by a plurality of spacer studs  6 , or wedges, mounted between the front wall  24  and the front skin  51 . Preferably, at least one spacer stud  6  comprises a radial passage opening for guiding a mechanical connection member L, for example, a rivet. Thus, when assembling the first module M 1  with the second module M 2 , the front wall  24  and the front skin  51  are spaced apart so as to form between them an air blow-out opening  32  comprising a guide channel, preferably of annular shape. Preferably, a spacer stud  6  has a radial thickness between 1 mm and 8 mm to form a guide channel of calibrated thickness. Preferably, the radial thickness depends on the desired de-icing conditions (temperature, pressure, etc.) 
     Advantageously, unlike the first embodiment, there is no need to drill through the front wall  24  of the first module M 1 , the blow-out opening  32  is here formed at the interface zone during assembly. Mechanical stresses in the front wall  24  of the first module M 1  are thereby limited. Such an offset blow-out opening  32  is known to the skilled person as “step down slot”. In this example, the blow-out opening  32  is circumferential. 
     With reference to  FIG. 8A , the internal wall  21  of the lip  2   a  comprises a radial discontinuity due to the gap between the front wall  24  and the front skin  51 . Alternatively, with reference to  FIG. 8C , the downstream end  24   a  of the front wall  24  is beveled, its radially inner surface converging radially outward along an upstream to downstream direction. Such a bevel is simple to make and significantly limits aerodynamic discontinuities at the interface between the front wall  24  and the front skin  51 . Good performance is achieved for a bevel angle θ less than 15° as illustrated in  FIG. 8C . Preferably, the radially internal surface is curved to form an aerodynamic profile. 
     According to a third embodiment, as illustrated in  FIG. 9 , the front skin  51  of the second module M 2  is curved so as to comprise an end portion  51   a  facing the front wall  24  of the first module M 1  to allow radial attachment and a central portion  51   b  as an extension of the front wall  24  of the first module M 1 . 
     In this embodiment, the front wall  24  and the front skin  51  have substantially the same shape as in the first embodiment but are radially spaced apart in a manner analogous to the second embodiment, in particular, by spacer studs  6  (not represented in  FIG. 9 ) and is in the form of an annular slot. 
     Advantageously, a blow-out opening  33  is formed here at the interface zone during assembly. The blow-out opening  33  comprises a guide channel extending longitudinally between the front wall  24  and the front skin  51  so as to guide the hot air flow. The blow-out opening  33  opens at the interface between the front wall  24  and the front skin  51  which are aligned. Such a buried blow-out opening  33  is known to the skilled person as “buried slot”. In this example, the blow-out opening  33  is circumferential. 
     According to one alternative of the invention, with reference to  FIG. 10 , when the blow-out opening  32 ,  33  comprises a guide channel formed between the front wall  24  and the front skin  51 , a filling member  7  can advantageously be provided in the guide channel so as to act on the hot air flow before it is discharged. 
     Preferably, the filling member  7  can comprise elementary channels in order to separate the hot air flow into a plurality of elementary flows so as to promote guidance and allow optimal de-icing. As an example, the filling member  7  comprises a corrugated panel sandwiched between two circumferential panels. Further preferably, the filling member  7  is made of a metallic material. 
     According to an alternative of the invention, with reference to  FIGS. 11A and 11B , the lip  2   a  comprises spacer studs  6 ′ having an aerodynamic profile so as to define an upstream-oriented leading edge and a downstream-oriented trailing edge. Preferably, a spacer stud  6 ′ is shaped like a drop of water as illustrated in  FIGS. 11A and 11B , the cross-section of which increases and then decreases from upstream to downstream. However, it goes without saying that each spacer stud could have a different shape 
     The spacer studs  6 ,  6 ′ (with an aerodynamic or non-aerodynamic profile) can be mounted as an insert between the front wall  24  and the front skin  51 , but can also be made of the material of the front wall  24  or of the front skin  51 . Preferably, the spacer studs  6 ,  6 ′ are made of the material of the front wall  24  and formed upon making the first module M 1 . 
     By virtue of the invention, a modular design makes it easier to hold and treat the modules M 1 , M 2 , since their overall size is limited and can be achieved with simpler and less expensive equipment. Furthermore, the risk of defects is limited because the modules M 1 , M 2  are accessible on each of their faces, which facilitates their inspection. Moreover, a modular assembly allows for various assembly solutions without affecting health of the modules M 1 , M 2 . 
     In particular, by virtue of the invention, mechanical characteristics of the internal wall  21  are preserved and it is no longer susceptible to deformation. The external wall  22  is also preserved since it is no longer introduced into a soldering furnace. Finally, the second acoustic module M 2  can simply be replaced in case of defect.