Abstract:
A structure ensuring acoustic attenuation of a flow of a first fluid and heat exchange between a first fluid and a second fluid. The structure includes a first wall which is perforated, a second wall, and a plurality of intermediate walls extending between the first wall and the second wall. For each intermediate wall, there is a pipe intended to receive the second fluid and inscribed within the intermediate wall. Such a structure makes it possible to optimally integrate the acoustic wave attenuation function and the heat exchange function.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This patent application claims priority to French patent application FR 16 53992, filed on May 5, 2016, the entire disclosure of which is incorporated by reference herein. 
       TECHNICAL FIELD 
       [0002]    The present disclosure relates to a structure ensuring attenuation of acoustic waves generated by the flow of a first fluid and also allowing heat exchange between the first fluid and a second fluid, as well as an aircraft having such a structure. 
       BACKGROUND 
       [0003]    A turbine engine of an aircraft, in particular a dual-flow turbine engine, has an air duct that opens to the front and through which fresh air enters the turbo engine. The air duct is defined by inner walls, which channel the air. Part of the air is used to perform heat exchange with the fluids of the aircraft. To this end, heat exchangers are implemented on the inner walls. 
         [0004]    The interior of the duct is also lined with structures attenuating acoustic waves generated by the flow of air in the air duct and thereby enabling attenuation of turbo engine noise. Such structures generally comprise a perforated wall that is oriented toward the inside of the duct and at the back of which is particularly arranged a set of honeycomb-shaped cavities. The cavities form quarter wave resonators which attenuate a specific frequency. 
         [0005]    An implementation of heat exchangers on the inner walls of the duct reduces the space allocated to the acoustic structures which may result in an increase in turbo engine noise. 
       SUMMARY 
       [0006]    A purpose of the present disclosure is to disclose a structure that attenuates acoustic waves generated by the flow of a first fluid and provides a thermal exchange between this first fluid and a second fluid. 
         [0007]    In relation thereto, a structure is disclosed providing acoustic attenuation of a flow of a first fluid and heat exchange between the first fluid and a second fluid, the structure having:
       a first wall which is perforated;   a second wall;   a plurality of intermediate walls extending between the first wall and the second wall; and   for each intermediate wall, a pipe intended to receive the second fluid and inscribed or defined within the intermediate wall.       
 
         [0012]    Such a structure makes it possible to optimally integrate the acoustic wave attenuation function and the heat exchange function. 
         [0013]    According to a particular embodiment, each pipe has an elliptical profile. 
         [0014]    Advantageously, the pipe is located at a distance from both the first wall and the second wall. 
         [0015]    According to an embodiment, the intermediate wall takes the form of a double wall consisting of or comprising two parallel walls between the first wall and the second wall and separated by a free space forming the pipe. 
         [0016]    Advantageously, the intermediate wall has a dividing wall which extends between the two walls of the intermediate wall and defines, at the first wall, a chamber separated from the pipe by the dividing wall. 
         [0017]    Advantageously, the structure comprises a partition wall integral with the intermediate wall and extending inside the pipe to separate the duct into two sub-pipes. 
         [0018]    Advantageously, the partition wall is a corrugated plate. 
         [0019]    Advantageously, the partition wall has through holes connecting both sides of the partition wall. 
         [0020]    According to a variant, each wall forming the intermediate wall has a part which extends beyond the first wall. 
         [0021]    According to another variant, each partition wall has a part that extends beyond the first wall. 
         [0022]    According to another variant, the structure has fins that extend along the first wall on the side opposite the pipes; each fin extends perpendicularly to the partition walls, and each fin is integral with the partition walls along which it is in contact. 
         [0023]    According to another variant, the structure has fins that extend along the first wall on the side opposite the pipes; each fin extends perpendicularly to the intermediate walls and is integral with the first wall. 
         [0024]    The disclosure herein also proposes an aircraft having a pod with an inner wall defining an air duct and where the inner wall is made up of structures according to one of the preceding variants, where the first wall is oriented toward the inside of the duct. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0025]    Characteristics of the disclosure herein mentioned above, and other characteristics, will become more apparent from the following description of an embodiment, the description given with reference to the enclosed example figures, which include: 
           [0026]      FIG. 1  shows a side view of a aircraft according to the disclosure herein; 
           [0027]      FIG. 2  shows a perspective view of a structure according to a first embodiment of the disclosure herein; 
           [0028]      FIG. 3  shows a perspective view of a structure according to a second embodiment of the disclosure herein; 
           [0029]      FIG. 4  shows a perspective view of a structure according to a third embodiment of the disclosure herein; 
           [0030]      FIG. 5  shows a perspective view of a structure according to a fourth embodiment of the disclosure herein; 
           [0031]      FIG. 6  shows a perspective view of a structure according to a fifth embodiment of the disclosure herein; and 
           [0032]      FIG. 7  shows a perspective view of a structure according to a sixth embodiment of the disclosure herein. 
       
    
    
     DETAILED DESCRIPTION 
       [0033]      FIG. 1  shows an aircraft  10  which has a pod  20  inside of which is arranged a turbo engine. The inner wall of the pod  20  defines an air duct which passes through the turbo engine. Each of  FIGS. 2 through 6  shows a structure that provides acoustic attenuation of a first fluid flowing along this structure and, heat exchange between the first fluid and a second fluid circulating inside of this structure. 
         [0034]    In the description that follows, each structure is described as forming part of an inner wall of a pod  20  of an aircraft  10 , but it can be used in another environment where it is necessary to attenuate the noise generated by the flow of a first fluid and to provide heat exchange between the first fluid and the second fluid. 
         [0035]      FIG. 2  shows a structure  100  according to a first embodiment structure which has:
       a first wall  102  which is perforated;   a second wall  104  located at a distance and, here, parallel to the first wall  102 ;   a plurality of intermediate walls  106  extending between the first wall  102  and the second wall  104 , here extending perpendicularly to the first wall  102  and to the second wall  104 ; and   for each intermediate wall  106 , a pipe  108  within the intermediate wall  106 .       
 
         [0040]    All the intermediate walls  106  are parallel to one another and thus create corridors  112  and the holes  110  in the first wall  102  ensure the passage between the outside of the first wall  102  and corridors  112 . 
         [0041]    In the case of  FIG. 2 , the pipes  108  are arranged at a distance from both the first wall  102  and of the second wall  104 . 
         [0042]    The intermediate walls  106  are made of a material of high thermal conductivity, such as a metallic material for example. 
         [0043]    In the case of a flow of the first fluid in a duct, the first wall  102  is oriented toward the inside of the duct. The first fluid, which is here the air of the duct, flows along the first wall  102  and the holes  110  allow part of the air to penetrate into the corridors  112  and thereby attenuate acoustic waves generated by the flow of the air. 
         [0044]    A second fluid, which can be oil for example, flows through the pipes  108  and the oil cools by heat exchange with the first fluid through the walls of the pipe  108  and intermediate walls  106 . 
         [0045]    The fact placing each pipe  108  at a distance from the first wall  102  limits the risks of damage to the pipes in the event of impacts on the first wall  102 . 
         [0046]    In the embodiment of the disclosure herein presented here, the structure  100  consists of or comprises a plurality of formed sections of substantially rectangular cross-section where the formed sections are secured to one other and where each pipe  108  is encapsulated between the two neighbouring walls of two adjacent formed sections. 
         [0047]    The structure can be assembled by all appropriate techniques according to the materials implemented, such as brazing, welding, and bonding from preformed or extruded parts, for example. 
         [0048]    The structure  100  ensures cross-current or parallel flow between the first fluid and the second fluid, in either a co-current or a counter-current flow configuration. 
         [0049]      FIG. 3  shows a structure  200  according to a second embodiment that features the same elements as the structure  100  according to the first embodiment except in that the structure  200  has a partition wall  214  that separates each pipe  208  in two sub-pipes  208   a - b . The partition wall  214  is also made of a material of high thermal conductivity. The partition wall  214  is integral with the intermediate wall  106  and extends it on the inside of the pipe  208 . Such a partition wall  214  improves the heat exchange between the first fluid and the second fluid. 
         [0050]    The structure  200  ensures cross-current or parallel flow between the first fluid and the second fluid, in either co-current or counter-current flow configurations. 
         [0051]      FIG. 4  shows a structure  300  according to a third embodiment having the same elements as the structure  200  according to the second embodiment except in that each partition wall  314  has a part  316  that extends beyond the first wall  102 , i.e. inside the duct in order ensure better heat exchange between the first fluid and the second fluid. Each part  316  is thus parallel to the partition wall  314  that it extends and to the pipes  208  of the structure  300 . The structure  300  ensures cross-current or parallel flow between the first fluid and the second fluid, in either co-current or counter-current flow configurations. 
         [0052]      FIG. 5  shows a structure  400  according to a fourth embodiment having the same elements as the structure  200  according to the second embodiment except that it has fins  416  that extend along the first wall  102  on the side opposite the pipes  208 . Each fin  416  is also made of a material of high thermal conductivity. Each fin  416  extends perpendicularly to the separation walls  414  and to the first wall  102 , and is integral with the partition walls  414  along which it is in contact. The structure  400  ensures a cross-current flow between the first fluid and the second fluid. 
         [0053]      FIG. 6  shows a structure  500  according to a fourth embodiment having the same elements as the structure  100  according to the first embodiment except that it has fins  516  that extend along the first wall  102  on the side opposite the pipes  108 . Each fin  516  is also made of a material of high thermal conductivity. Each fin  516  extends perpendicularly to the intermediate walls  106  and the first wall  102 , and is integral with the first wall  102 . The structure  500  ensures a cross-current flow between the first fluid and the second fluid. 
         [0054]    In a preferred embodiment, each pipe  108 ,  208  has an elliptical and non-circular profile, in particular with a ratio between the length of the major axis and the length of the minor axis in the order of 4 to 1. When a partition wall  214 ,  314 ,  414  is present, the pipe  208  takes the shape of two half-ellipses  208   a  and  208   b . The elliptical shape increases the useful heat exchange surface area while limiting the surface area that is not acoustically treated. 
         [0055]    In the embodiment of the disclosure herein presented in  FIGS. 2 through 6 , the major axis is perpendicular to the first and second walls  102  and  104 . 
         [0056]    The intermediate walls  106  are deformed by the presence of the pipes  108  and  208  and these distortions create a narrowing of the corridors  112  at the level of the pipes  108  and  208 . 
         [0057]    The placement of pipes  108 ,  208  of elliptical cross-section allows greater fluid flow cross-sections to be obtained in relation to circular cross-sections having the same impact on the acoustic surface treatment, which limits hydraulic head losses. 
         [0058]    The elliptic cross-sections also make it possible to boost the heat exchange coefficient particularly when the width of the corridor becomes small in comparison with its height. 
         [0059]    The elliptical sections also make it possible to have a heat exchange surface area between the fluid and the intermediate walls  106 , and this exchange surface area is further increased when a partition plate is integrated into the pipe. 
         [0060]    To increase the contact surface of the fluid in the pipe  208 , split into two sub-pipes  208   a - b , the partition wall  214 ,  314 ,  414  can be a corrugated plate. 
         [0061]    Whether the partition wall  214 ,  314 ,  414  is corrugated or flat, it can have through holes connecting both sides of the partition wall  214 ,  314 ,  414  to ensure better homogenisation of the temperature of the second fluid and participate in the creation of local turbulence increasing the heat exchange coefficient on the side of the second fluid thus the exchange in general. 
         [0062]    In the examples illustrated in  FIGS. 2 through 6 , the pipes  108 ,  208  are centred at mid-height of the partition walls  106  but moving them towards the first wall  102  helps to minimize the thermal resistance related to the length between the first wall  102  and the walls of the pipes  108 ,  208 . 
         [0063]      FIG. 7  shows a structure  600  according to a fifth embodiment which has:
       a first wall  102  which is perforated;   a second wall  104 ;   a plurality of intermediate walls  606  extending between the first wall  102  and the second wall  104 ; and   for each intermediate wall  606 , a pipe  608  intended to receive a fluid and inscribed or defined within the intermediate wall  606 .       
 
         [0068]    All the intermediate walls  606  are parallel to one another and thus create corridors  112  and the holes  110  in the first wall  102  ensure the passage between the outside of the first wall  102  and corridors  112 . 
         [0069]    In the case of  FIG. 7 , the intermediate wall  606  takes the form of a double wall consisting of or comprising two parallel walls extending between the first wall  102  and the second wall  104  and separated by a free space forming the pipe  608 . That is to say that the pipe  608  is arranged between the two walls forming the intermediate wall  606 . 
         [0070]    The intermediate wall  606  has a dividing wall  612  which extends between the two walls of the intermediate wall  606  and defines, at the level of the first wall  102 , a chamber  610  separated from the pipe  608  by the dividing wall  612 . The pipe  608  is thus separated from the first wall  102  and by the chamber  610  which is filled with air or empty. Thus, in case of very high mechanical loads or in the case of impact, the chamber  610  constitutes a barrier which prevents the first fluid from mixing with the second fluid, by absorbing a part of the deformation energy. 
         [0071]    As with the previous embodiments, the structure  600  may have a partition wall  614 , possibly corrugated and pierced, integral with the intermediate wall  606  and extending inside the pipe  608  to separate the pipe  608  into two sub-pipes. The partition wall  614  can be corrugated and/or pierced. 
         [0072]    The structure  600  can also include fins in accordance with those of the embodiment shown in  FIG. 6 . 
         [0073]    The structure  600  can also have fins  616  which are derived from an extension of the walls forming the intermediate wall  606  beyond the first wall  102 . In other words, each wall forming the intermediate wall  606  has a part  616  that extends beyond the first wall  102 . 
         [0074]    While at least one exemplary embodiment of the invention(s) is disclosed herein, it should be understood that modifications, substitutions and alternatives may be apparent to one of ordinary skill in the art and can be made without departing from the scope of this disclosure. This disclosure is intended to cover any adaptations or variations of the exemplary embodiment(s). In addition, in this disclosure, the terms “comprise” or “comprising” do not exclude other elements or steps, the terms “a”, “an” or “one” do not exclude a plural number, and the term “or” means either or both. Furthermore, characteristics or steps which have been described may also be used in combination with other characteristics or steps and in any order unless the disclosure or context suggests otherwise. This disclosure hereby incorporates by reference the complete disclosure of any patent or application from which it claims benefit or priority.