Abstract:
A nacelle for an aircraft bypass turbofan engine includes an upstream section via which an airflow enters, a middle section surrounding the fan of the turbofan and a downstream section having an inner structure and an outer structure delimiting a flow duct in which the air flows. The outer structure includes one cowling movably mounted on the inner fixed structure. The nacelle also has a top to accept a pylon for attaching a wing of the aircraft. The nacelle further includes one first panel mounted on the inner structure on one side of the nacelle and one second panel mounted on the other side of the nacelle. The first panel undergoes a physical interference with a part of the wing. The second panel increases the air removed from this other side of the nacelle during thrust reversal.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of International Application No. PCT/FR2011/052706, filed on Nov. 18, 2011, which claims the benefit of FR 10/60478, filed on Dec. 14, 2010. The disclosures of the above applications are incorporated herein by reference. 
    
    
     FIELD 
     The present disclosure relates to a nacelle for bypass turbofan engine as well as an aircraft comprising such a nacelle. 
     BACKGROUND 
     The statements in this section merely provide background information related to the present disclosure and may not constitute prior art. 
     An aircraft is moved by several turbofan engines each housed in a nacelle also housing a set of related actuating devices connected to its operation and performing various functions when the turbofan engine is running or stopped. These related actuating devices in particular comprise a mechanical thrust reverser actuating system. 
     A nacelle generally has a tubular structure with a longitudinal axis comprising an air inlet upstream from the turbofan engine, a middle section designed to surround the fan of the turbofan engine, and a downstream section housing thrust reversal means and designed to surround the combustion chamber of the turbofan engine. The tubular structure generally ends with a jet nozzle whereof the output is situated downstream from the turbofan engine. 
     The nacelle also typically includes a top designed to receive a fastening pylon making it possible to fasten the nacelle and the turbofan engine to a wing of the aircraft. 
     The term “downstream” here refers to the direction corresponding to the direction of the cold air flow penetrating the turbofan engine. The term “upstream” designates the opposite direction. 
     Modern nacelles are designed to house a bypass turbofan engine capable of generating, by the rotating blades of the fan, a hot air flow (also called “primary flow”) coming from the combustion chamber of the turbofan engine, and a cold air flow (“secondary flow”) that circulates outside the turbofan engine through an annular passage, also called “tunnel.” 
     A turbofan engine typically includes a so-called “upstream” part, comprising the blades of the fan, and a so-called “downstream” part, housing the gas generator. 
     The downstream section of the nacelle for such an engine generally has an outer structure, called Outer Fixed Structure (OFS), and a concentric inner structure, called Inner Fixed Structure (IFS), surrounding the structure of the engine strictly speaking downstream from the fan. The inner and outer structures define a tunnel designed to channel the cold air flow that circulates outside the engine. The outer structure in some cases includes a thrust reverser comprising one or more cowls sliding along the longitudinal axis of the nacelle between the position allowing a reversed flow of air to escape and a position preventing such escape. 
     Such a thrust reverser makes it possible, owing to the reversed flow of air, to reduce the braking distance of the aircraft upon landing. 
     An airplane wing is also generally equipped with spoilers that make it possible to orient the aircraft. A spoiler is situated on the front face of the wing. When a spoiler is in the lowered position, it becomes very close to the nacelle, in particular at the fastening of the latter under the wing of the aircraft, only on the nacelle side. 
     This risks creating a physical interference, as well as an aerodynamic interference with the sliding cowl of the thrust reverser, when the latter slides toward the thrust reversal position. 
     One proposed solution to eliminate this interference is to make the upper part of the nacelle stationary, i.e., the top of the latter corresponding to the fastening area of the nacelle under the wing of the aircraft, while widening the inner fixed structure. 
     The aircraft being symmetrical, all of the nacelles mounted thereon experience this interference phenomenon, with the result that all of the nacelles have a stationary area with respect to the thrust reverser on either side of the top of the nacelle. 
     The stationary area of the nacelle therefore does not participate in the thrust reversal performance. In order to offset this drawback, it is necessary to increase the travel length of the thrust reverser. 
     Such a modification causes an increase in the mass of the nacelle and a decrease in the effectiveness of the counterthrust. 
     One aim of the present disclosure is therefore to provide a nacelle not having the aforementioned drawbacks. 
     SUMMARY 
     The present disclosure provides a nacelle for a bypass turbofan engine including an upstream section through which the flow of air is designed to penetrate, a middle section designed to surround the fan of the turbofan engine, and a downstream section comprising an inner structure and an outer structure delimiting a tunnel through which the flow of air is designed to flow, the outer structure comprising at least one cowl mounted on the inner structure and movable along the longitudinal axis of the nacelle so as to allow the evacuation of at least part of the flow of air circulating in the tunnel during a thrust inversion phase of the nacelle, the nacelle also having a top designed to receive a fastening pylon for a wing of the aircraft, said nacelle comprising:
         at least one first panel mounted on the inner structure of one side of the nacelle, with respect to the top, that is designed to undergo a more significant physical interference with an element of the wing than the other side of the nacelle, said panel being arranged to limit the physical interference of said cowl with said wing element during thrust reversal, and   at least one second panel mounted on the other side of the nacelle, with respect to the top, said panel being arranged to increase the air discharged from the other side of the nacelle during thrust reversal.       

     Owing to the presence of the first and second panels, the nacelle according to the present disclosure advantageously makes it possible to increase the available surface for the flow of air discharged during thrust reversal, in particular on the side of the nacelle where the flow of air does not encounter interference with certain elements of the wing. It is therefore no longer necessary to increase the mass of the nacelle or to decrease the counterthrust performance. 
     According to other features of the present disclosure, the nacelle includes one or more of the following optional features, considered alone or according to any possible combinations: 
     said first panel is selected from the group comprising: a panel fixed to the inner fixed structure and stationary or at least partially movable with respect to that inner fixed structure, and a panel fixed to said moving cowl and stationary or at least partially movable with respect to said moving cowl; 
     said second panel is selected from the group comprising: a panel fixed to the moving cowl, a panel fixed to the inner structure and comprising at least one movable portion with respect to said inner structure, and a panel movably mounted on said moving structure; 
     the second panel is secured to said moving cowl: this makes it possible to simply and effectively increase the outlet surface area of the deflected flow of air on one side of the nacelle; 
     mistake-proofing means are provided to indicate the position of the second panel on the nacelle, which makes it possible to simplify assembly; 
     the first panel and/or the second panel include at least one movable part configured to go from a closed position preventing the part of the flow of air from escaping to an open position allowing such escape, which makes it possible to still further increase the outlet surface of the flow of air; 
     the movable part of the first panel and/or the second panel is configured to assume several intermediate positions, which makes it possible to adapt the deflected flow of air, in particular as a function of the interference undergone; 
     the movable part is pivotably mounted on the inner structure around an axis substantially parallel to the axis of the nacelle, 
     the movable part is connected to said inner structure by hinges and several connecting rods, whereof at least one connecting rod is fixed on the movable part and on the moving cowl and a second connecting rod is fixed on the movable part and on the inner structure; 
     the movable part is pivotably mounted on the outer skin of said moving cowl toward the inside thereof, around an axis chosen from among the group comprising a substantially parallel axis, and a substantially perpendicular axis, with respect to the axis of the nacelle; 
     said movable part is secured to the outer skin of said moving cowl, and movable due to its elasticity; 
     said movable part is guided by means selected from among the group comprising a rail and a border secured to a beam situated at the top of said nacelle; 
     the first and second panels have a substantially symmetrical shape with respect to the top of the nacelle, which makes it possible to have panels that are very easily interchangeable, simplifying the installation and maintenance of the nacelle. 
     According to another aspect, the present disclosure relates to an aircraft including a wing and a nacelle according to the present disclosure connected by a fastening pylon. 
     Further areas of applicability will become apparent from the description provided herein. It should be understood that the description and specific examples are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure. 
    
    
     
       DRAWINGS 
       In order that the present disclosure may be well understood, there will now be described various forms thereof, given by way of example, reference being made to the accompanying drawings, in which: 
         FIG. 1  is a partial diagrammatic cross-section of one form of the nacelle according to the present disclosure; 
         FIGS. 2 and 3  are diagrammatic perspective views of the top of a first form of the nacelle according to the present disclosure; 
         FIG. 4  is an enlargement of area IV seen from below of the second panel and the moving cowl of the form of the nacelle of  FIG. 2 ; 
         FIGS. 5 to 9  are diagrammatic perspective views of the top of a second form of the nacelle according to the present disclosure; 
         FIG. 10  is a substantially frontal perspective view of part of the inner structure of the form of the nacelle  FIG. 5 ; 
         FIG. 11  is a substantially frontal perspective view of the movable part of the inner structure of the form of the nacelle of  FIG. 5 ; 
         FIG. 12  is a substantially side perspective view of part of the inner structure of the form of the nacelle  FIG. 10 ; 
         FIG. 13  is a substantially side perspective view of part of the moving cowl of the form of the nacelle  FIG. 5 ; 
         FIG. 14  is a substantially side perspective view of the form shown in  FIG. 5  when the movable part  136   b  is positioned so as to allow part of the flow of air to escape; 
         FIGS. 15 and 16  are perspective views of another form of the present disclosure, in the normal and thrust reversal configurations, respectively; 
         FIGS. 17 and 18  are diagrammatic views of means for guiding the moving panel of  FIGS. 15 and 16 ; 
         FIG. 18 a    shows an alternative of the detail of the zone Z of  FIG. 18 ; 
         FIGS. 19 to 25  are diagrammatic views of other means for guiding the moving panel of  FIGS. 15 and 16 , and 
         FIGS. 26 and 27  are perspective views similar to those of  FIGS. 15 and 16 , of still another form of the present disclosure. 
     
    
    
     The drawings described herein are for illustration purposes only and are not intended to limit the scope of the present disclosure in any way. 
     DETAILED DESCRIPTION 
     The following description is merely exemplary in nature and is not intended to limit the present disclosure, application, or uses. It should be understood that throughout the drawings, corresponding reference numerals indicate like or corresponding parts and features. 
     These figures show an orthogonal trihedron X, Y, Z, whereof the directions are respectively parallel to the axis of the nacelle, perpendicular to the axis and the vertical, and vertical. 
     As shown in  FIG. 1 , a nacelle  1  according to the present disclosure has a substantially tubular shape along a longitudinal axis Δ (direction parallel to X). The nacelle  1  according to the present disclosure comprises an upstream section  2  with an air intake lip  3 , a middle section  4  surrounding a fan  5  of a turbofan engine  6 , and a downstream section  7 . The downstream section  7  comprises an inner structure  8  (also called “inner fixed structure” or “IFS”) surrounding the upstream part of the turbofan engine  6 , an outer structure (also called “outer fixed structure” or “OFS”)  9  and a moving cowl (not shown) including thrust reversal means. The inner structure or IFS  8  as well as the outer structure or OFS  9  are stationary relative to the moving cowl. 
     The IFS  8  and the OFS  9  define a tunnel  10  allowing the passage of the flow of air  12  penetrating the nacelle  1  according to the present disclosure at the air intake lip  3 . 
     The nacelle  1  according to the present disclosure includes a top  14  designed to receive a fastening pylon  16  making it possible to fasten said nacelle  1  to a wing of the aircraft (not shown). To that end, said top  14  includes means (not shown) for fastening said pylon  16 . 
     The nacelle  1  according to the present disclosure ends with a jet nozzle  21  comprising an outer module  22  and an inner module  24 . The inner  24  and outer  22  modules define a primary air flow  25 , called hot flow, leaving the turbofan engine  6 . 
     As shown in  FIG. 2 , the OFS  9  comprises at least one cowl  31  mounted on the IFS  8  and movable along the longitudinal axis Δ so as to allow the discharge of the flow of air  12  circulating in the tunnel  10  during a thrust reversal phase. 
     The nacelle  1  according to the present disclosure comprises at least one first panel  33  that is stationary relative to the IFS  8  and fixed thereto  8  on the side, with respect to the top  14 , designed to be near the wing and a second panel  35  that is movable relative to the IFS  8  and fixed thereto  8  or to the moving cowl  31  on the side, with respect to the top  14 , designed to be at a distance from the wing, the first and second panels  33  and  35  being mounted on either side of the top  14 . The second panel  35  is configured so as to allow part of the flow of air  12  to be discharged. 
     In other words, when the flow of air  12  circulating in the tunnel  10  is deflected by the thrust reversal means of the nacelle  1  according to the present disclosure, part of that deflected flow of air passes through the passage freed by the moving cowl  31  in the deployed thereof and another part through the passage freed by the second moving panel  35 . As a result, a greater portion of the flow of air  32  can thus be discharged. 
     The wing (not shown) of the aircraft on which the nacelle  1  according to the present disclosure is attached typically includes elements that can cause interference with the moving cowl  31 . Examples include spoilers  37  facilitating the landing and braking of the aircraft (see  FIGS. 2, 3 and 5 to 9 ). The spoilers  37  are not present on each side of the nacelle  1  of the present disclosure. 
     In the nacelle  1  according to the present disclosure, the first panel  33  is positioned so as to be near or under the spoiler of the wing when the nacelle is mounted on the wing. In other words, for a left wing when looking at the aircraft from the front, the first panel  33  is mounted to the left of the top  14  of the nacelle according to the present disclosure when the latter is examined from the front, i.e., facing the air intake. 
     For a right wing, when looking at the aircraft from the front, the first panel  33  is mounted to the right of the top  14  of the nacelle according to the present disclosure when the latter  1  is seen from the front, i.e., across from the air intake. The second panel  35  is mounted on the right in the first scenario and on the left in the second scenario. 
     The nacelle  1  according to the present disclosure advantageously makes it possible to preserve the available surface for the deflected flow of air  32  on the side of the top  14  where a physical interference exists between the nacelle and certain elements of the wing. It is therefore no longer necessary to increase the mass of the nacelle or to decrease the counterthrust performance. 
     Preferably, the first panel  33  is mounted on the IFS  8  on the side of the nacelle  1  according to the present disclosure with respect to the top  14  designed to have a greater physical interference or bulk with an element of the wing, in the present case a spoiler  37 , than on the side where the second movable panel  35  is mounted. 
     The first and second panels  33  and  35  may be of any shape adapted to the quantity of the deflected flow of air  32  and, in particular, with a shape complementary to the moving cowl  31 . As shown in the figures, the first stationary panel  33  and the second moving panel  35  may have an oblong shape. 
     According to one form shown in  FIGS. 2 to 4 , the second panel  35  can be translated along the longitudinal axis Δ of the nacelle, which makes it possible, simply and effectively, to increase the outlet surface of the deflected flow of air  32  on the side of the nacelle  1  according to the present disclosure. To that end, the second panel  35  is securely fastened to the moving cowl  31  by fastening means, such as bolts  41 , which makes it possible to drive the moving cowl  31  and the second panel  35  simultaneously (see  FIG. 4 ). 
     The first and/or second panels  33  and  35  may be formed in a single piece, or on the contrary, in several pieces. As shown in  FIGS. 2 and 3 , each panel  33  and  35  is formed from two parts  36  and  38 . In the case of the first panel  33 , the parts  36   a  and  36   b  are fastened to each other rigidly without allowing any mobility therebetween. The part  36   b  in contact with the moving cowl  31  is not fastened thereto, with the result that, when the moving cowl  31  moves, the parts  36   a  and  36   b  remain stationary like the IFS  8 , with respect to the moving cowl  31 . 
     In the case of the second moving panel  35 , the two parts  38   a  and  38   b  are not fastened to each other, with the result that they may be movable with respect to one another. Thus, one part  38   a  is rigidly fastened to the IFS  8 , and the other part  38   b  is rigidly fastened to the moving cowl  31 . As a result, when the cowl  31  is movable, it advantageously drives the part  36   b  connected to said cowl  31 . The fact that the second panel  35  and/or the first panel  33  are formed in several pieces allows a simple and quick transformation of a moving panel into a first panel and vice versa by suitable fastening of the parts with respect to one another. 
     The first and second panels  33  and  35  must have a substantially symmetrical shape with respect to the top  14  of the nacelle  1  of the present disclosure, which makes it possible to have first and second panels  33  and  35  that are easily interchangeable, still further simplifying the installation and maintenance of the nacelle  1  according to the present disclosure. In fact, to change panels  33  or  35 , one need only modify the fastening of the panels so that a panel becomes stationary or movable as needed. 
     The nacelle  1  according to the present disclosure may comprise mistake-proofing means (not shown) configured to indicate the position of the second panel  35  on the nacelle  1  according to the present disclosure, which makes it possible to assist and simplify the assembly of the first and second panels  33  and  35 . 
     The mistake-proofing means may be a finger cooperating with an interfaced bolt, for example. 
     According to another form shown in  FIGS. 5 to 14 , the second panel (not shown) and/or the first panel  133  includes at least one part  136   b  that is rotatable relative to the IFS  8  and configured to go from a closed position preventing part of the flow of air  132  from escaping to an open position allowing such an escape. 
     As a result, the nacelle  1  according to the present disclosure may have a second panel including a part that is rotatable with respect to the IFS  8  and a first panel not including such a part. It is also possible for the first and second panels  133  and  135  each to comprise a part  136   b  that is rotatable with respect to the IFS  8 . As a result, the available surface for the deflected flow of air is still further optimized. 
     In the form of  FIG. 14 , the first panel  133  includes a moving part  136   b  allowing the part  132  of the deflected flow of air  32  to escape. Thus, the escape surface of the deflected flow of air  32  is larger. 
     The first and/or second panels  133  may be made up of several pieces  136   a ,  136   b ,  136   c , whereof one piece  136   b  is movable with respect to the IFS  8 . As before, the fact that the second panel and/or the first panel  133  is made up of several pieces allows a simple and quick transformation of the moving panel into a stationary panel and vice versa by suitable fastening of the parts with respect to each other. 
     In the context of the second panel (not shown), the part in contact with the moving cowl can be fastened thereto so as to be able to slide along the longitudinal axis Δ of the nacelle  1  according to the present disclosure. To that end, said part driven by the moving cowl is not fastened to the rotatable part. 
     The rotatable part  136   b  may assume any shape and any size suitable for allowing the desired release of the deflected flow of air  132 . 
     It is possible to limit the angle of the rotatable part  136   b  of the first panel  133  and/or the second panel. To that end, an additional connecting rod may be attached on the front frame. 
     The moving part  136   b  may be rotatable by means of fastening means fixed on the IFS  8  and on the moving cowl  31 . As shown in  FIGS. 10 to 13 , the fastening means enabling the rotation of the moving part  136   b  may be articulation devices, of the hinge type  139 , mounted on the moving part  136   b  and on the front frame  140  of the IFS. Thus, for example, the nacelle  1  according to the present disclosure may comprise one or more of these devices  139 , in particular three. 
     The fastening means may also comprise several connecting rods, in particular two connecting rods whereof a first connecting rod  145  is fastened on the IFS  8 , in particular on the front frame  141 , by a connecting rod fastener  146 , and a connecting rod  147  is fastened on the moving cowl  31  by another connecting rod fastener  148 . The connecting rods  145  and  146  are also connected to the moving part  135  by means of connecting rod fasteners  151 . This makes it possible to rotate the moving part  136   b  substantially simultaneously with the moving cowl  31 . 
     In other words, it is possible to convert the translation of the moving cowl  31  into a rotation of the second articulated panel. 
     Advantageously in this embodiment, it is not necessary to have a mistake-proofing device if the second moving panel and the first stationary panel are symmetrical. In fact, if one wishes to prevent a part from being rotatable, said part need only be securely fastened to the IFS  8  and the connecting rods  145  and  147  disengaged. As a result, the uninstallation and installation of the first and first panels  135  and  133  are further facilitated. 
     In the form of  FIGS. 15 and 16 , at least the second panel  235  is pivotably mounted on the outer skin  31   a  of the moving cowl  31 , around an axis Δ substantially parallel to the axis Δ of the nacelle, and that panel is opened toward the inside of the sliding cowl  31 , when the latter goes from its normal position ( FIG. 15 ) to its thrust reversal position ( FIG. 16 ). 
     As shown in  FIGS. 17 and 18 , the opening of the panel  235  toward the inside of the sliding cowl  31  may be obtained by suitable guiding of that panel using the rail R secured to the beam P that is located at the top of the nacelle, and which enables the connection thereof with the pylon  14 . 
     More specifically, as shown in  FIG. 18 , this rail R may be inclined with respect to the primary R 1  and secondary R 2  rails in which the outer  31   a  and inner  31   b  skins of the moving cowl  31  slide, respectively, or may assume any suitable shape like that shown in  FIG. 18 a   , making it possible to optimize the desired flows of air. 
     In the alternatives shown in  FIGS. 19 to 25 , the panel  235  is no longer guided by a rail, but by a simple border B secured to the beam P, against which it is elastically recalled, a strip of material with a low friction coefficient such as Teflon T being able to be inserted between said border B and said panel  235 . 
     More specifically, in the alternatives of  FIGS. 20 and 21 , spring means RE, positioned in the region where the hinges C articulating the panel  235  relative to the outer skin  31   a  of the cowl  31  are found, return the panel  235  into contact with the border B. 
     In the alternative of  FIG. 20 , the edge of the panel P that is in contact with the border B has an indentation D making it possible to obtain an optimal aerodynamic profile. 
     In the alternative shown in  FIGS. 22 and 23 , the moving panel  235  is no longer articulated on the outer skin  31   a  of the moving cowl  31 , but is kept bearing against the border B due solely to its elasticity. 
     More specifically, in the alternative of  FIG. 22 , this panel  235  is an attached piece, mounted stationary in the outer skin  31   a  of the moving cowl  31 , and having greater elasticity than that cowl. 
     In the alternative of  FIG. 23 , this panel  235  is an integral part of the outer skin  31   a  of the moving cowl, and is formed in part of the outer skin that has a greater elasticity. 
     As shown in  FIGS. 24 and 25 , during sliding of the moving cowl  31  from its normal position ( FIG. 24 ) toward its thrust reversal position ( FIG. 25 ), the panel  235  is guided toward its opening position by the border B. 
     In the form of  FIGS. 26 and 27 , the second panel  235  is also pivotably mounted on the outer skin  31   a  of the sliding cowl  31 , but the axis of rotation A′ in that case extends in a direction substantially parallel to the axis Y. 
     Although the present disclosure has been described with a particular exemplary form, it is quite obvious that it is by no means limited thereto and that it comprises all the technical equivalents of the described means, as well as their combinations if the latter enter the scope of the present disclosure.