Abstract:
A bypass turbojet engine nacelle equipped with a thrust reverser device is provided that includes a cowl with translational mobility and a diversion means supported by a front frame upstream of the cowl. A variable-geometry jet pipe nozzle is mounted at a downstream end of the cowl and is translatable in a direction substantially parallel to a longitudinal axis of the nacelle towards at least one position that causes a variation in its cross-section. At least part of the front frame, the diversion means, and the jet pipe nozzle form an assembly having translational mobility in a direction substantially parallel to a longitudinal axis of the nacelle in a downstream direction of the nacelle towards a position that causes a variation in the cross-section of the jet pipe nozzle, the cowl being in the closed position during that movement of said assembly.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a continuation of International Application No. PCT/FR2011/050924 filed on Apr. 21, 2011, which claims the benefit of FR 10/53373, filed on Apr. 30, 2010. The disclosures of the above applications are incorporated herein by reference. 
     
    
     FIELD 
       [0002]    The present disclosure relates to a turbojet engine nacelle comprising a variable jet pipe nozzle geometry and also to a method implemented by such a nacelle. 
       BACKGROUND 
       [0003]    The statements in this section merely provide background information related to the present disclosure and may not constitute prior art. 
         [0004]    An airplane is moved by several turbojet engines each housed in a nacelle also housing a set of related actuating devices connected to its operation and performing various functions when the turbojet engine is running or stopped. 
         [0005]    These related actuating devices in particular comprise a thrust reverser device. 
         [0006]    More specifically, a nacelle generally has a tubular structure comprising an air intake upstream of the turbojet engine, a middle section designed to surround a fan of the turbojet engine, a downstream section housing the thrust reverser means and designed to surround the turbojet engine combustion chamber, and generally ends with a jet pipe nozzle located downstream of the turbojet engine. 
         [0007]    This nacelle is designed to house a bypass turbojet engine capable of generating, through the rotating fan blades, a flow of hot air, coming from the combustion chamber of the turbojet engine, and a flow of cold air that circulates outside the turbojet engine through an annular tunnel. 
         [0008]    The thrust reverser device is designed, during landing of the aircraft, to improve the braking capacity thereof by orienting at least part of the thrust generated by the turbojet engine forward. 
         [0009]    In that phase, the thrust reverser device obstructs the cold air flow tunnel and orients the latter toward the front of the nacelle, thereby generating a counter-thrust that is added to the braking of the aircraft&#39;s wheels. 
         [0010]    The means used to perform this reorientation of the cold air flow vary depending on the type of reverser. 
         [0011]    However, in all cases, the structure of a reverser comprises a movable cowl that can be moved on the one hand between a deployed position, in which it opens a passage in the nacelle designed for the deflected air flow, and on the other hand a retracted position, in which it closes the passage. 
         [0012]    This cowl may perform a cascade function, or simply serve to activate other cascade means. 
         [0013]    In the case of a cascade vane thrust reverser, the flow of air is reoriented by cascade vanes, associated with reverser flaps, the cowl performing only a sliding function aiming to expose or cover the cascade vanes. 
         [0014]    The reverser flaps form blocking doors that may be activated by sliding of the cowl, causing closing of the tunnel downstream of the grids, so as to optimize the reorientation of the flow of cold air. 
         [0015]    Furthermore, aside from its thrust reversal function, the sliding cowl belongs to the rear section and has a downstream side forming the jet pipe nozzle aiming to channel the discharge of the flows of air. 
         [0016]    This nozzle provides the power necessary for propulsion by imparting a speed to the exhaust stream and modulates the thrust by varying the outlet area thereof in response to variations of the adjustment of the power of the engine and flight conditions. 
         [0017]    This nozzle is associated with an actuating system that may or may not be independent from that of the cowl, making it possible to vary and optimize the section thereof as a function of the current flight phase of the aircraft. 
         [0018]    One recurring problem in this type of thrust reverser is the limited space dedicated to the flow passage section of the tunnel. 
       SUMMARY 
       [0019]    The present disclosure includes a nacelle in which the space available for the cascade vanes in the thrust reverser device is improved, along with the space available for the cold flow tunnel. 
         [0020]    To that end, the present disclosure relates to a bypass turbojet engine nacelle equipped with a thrust reverser device comprising a cowl, diversion means supported by a front frame upstream of the cowl, said cowl having translational mobility in a direction substantially parallel to a longitudinal axis of the nacelle and being able alternately to move from a closed position in which it ensures the aerodynamic continuity of the nacelle and covers the diversion means, into an open position in which it opens up a passage in the nacelle and uncovers the diversion means, said cowl being extended by at least one variable-geometry jet pipe nozzle mounted at a downstream end of said cowl, remarkable in that at least part of the front frame, the diversion means and the jet pipe nozzle have translational mobility in a direction substantially parallel to a longitudinal axis of the nacelle with respect to the cowl towards a position that causes a variation in the cross-section of the jet pipe nozzle. 
         [0021]    More particularly, at least part of the front frame, the diversion means and jet pipe nozzle form an assembly having translational mobility in a direction substantially parallel to a longitudinal axis of the nacelle in the downstream direction of the nacelle, reversibly, toward a position causing a variation in the cross-section of the jet pipe nozzle, the cowl being in its closed position during the movement of said assembly. Owing to the present disclosure, in which a thrust reverser device is proposed with two independent moving assemblies, i.e. a jet pipe nozzle, a front frame and diversion means movable independently from the cowl, the increase of the passage section of the flow in the tunnel is favored. 
         [0022]    According to particular forms of the invention, a device according to the present disclosure may comprise one or more of the following features, considered alone or in technically possible combinations:
       the front frame comprises a support element for the diversion means, said support element being translatable with the jet pipe nozzle when it is moved toward a position causing a variation in the cross-section of the jet pipe nozzle;   the diversion means are extended downstream by a rear frame secured to the jet pipe nozzle, said rear frame being translatable with the jet pipe nozzle when it is moved toward a position causing a variation in the section of the jet pipe nozzle;   the jet pipe nozzle is suitable for sliding inside the cowl;   the jet pipe nozzle comprises first and second covering panels ensuring covering between the jet pipe nozzle and an outer shroud and an inner shroud of the cowl, respectively;   a rail-guideway assembly is formed between the first covering panel of the jet pipe nozzle and the outer shroud of the cowl;   the nacelle also comprises a middle section upstream of the thrust reverser device, at least the support element of the front frame and at least part of the diversion means are housed in said middle section;   the diversion means comprise cascade vanes and an upstream extension structure of said vanes suitable for ensuring limited downstream movement of the front frame;   the front frame comprises a front stationary part designed to provide support, through discrete fittings, for the middle section of the nacelle;   the front frame comprises a support surface sliding between the middle section and the front frame;   the nacelle also comprises means for actuating the cowl placed between two reverser flaps, under the surface producing the pressure barrier for the cold air tunnels;   the nacelle also comprises means for actuating the jet pipe nozzle, cascade vanes and at least part of the front frame placed between two adjacent cascade vanes.       
 
         [0034]    The invention also relates to a method implemented with the nacelle as described above in which part of the front frame, the diversion means and the jet pipe nozzle are translated in a direction substantially parallel to a longitudinal axis of the nacelle in relation to the cowl toward a position causing a variation in the cross-section of the jet pipe nozzle. 
     
    
     
       DRAWINGS 
         [0035]    Other features, aims and advantages of the present invention will appear upon reading the following detailed description, according to embodiments provided as non-limiting examples, and in reference to the appended drawings, in which: 
           [0036]      FIG. 1  is a partial cross-sectional view of a first embodiment of the nacelle according to the present disclosure; 
           [0037]      FIG. 2  is a partial cross-sectional view of a second embodiment of a nacelle according to the present disclosure; 
           [0038]      FIGS. 3   a  to  3   c  are respective cross-sectional views of a nacelle according to  FIG. 1 , wherein the jet nozzle respectively has a nominal, increased, and reversed jet section; 
           [0039]      FIG. 4  shows a perspective view of air flow diversion means of a nacelle according to  FIG. 1 ; and 
           [0040]      FIGS. 5 to 7  illustrate cross-sectional views of a nacelle according to  FIG. 1 , illustrating the actuating means in positions for which the jet pipe nozzle respectively has an increased, nominal, and reversed jet section. 
       
    
    
     DETAILED DESCRIPTION 
       [0041]    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. 
         [0042]    A nacelle is designed to form a tubular housing for a bypass turbojet engine and serves to channel the flows of air that it generates through fan blades, i.e. a flow of hot air passing through the combustion chamber and a flow of cold air circulating outside the turbojet engine. 
         [0043]    The nacelle generally has a structure comprising an upstream section forming an air intake, a middle section  1  surrounding the fan of the turbojet engine, and a downstream section surrounding the turbojet engine, designated by general reference  2  in  FIG. 1 . 
         [0044]    In reference to this figure, the downstream section  2  comprises an outer structure  10  including a thrust reverser device  20  and an inner engine fairing structure  11  defining, with the outer structure  10 , a tunnel  12  designed for the circulation of a cold flow in the case of a bypass turbojet engine as presented here. 
         [0045]    The thrust reverser device  20  comprises a moving cowl  30  translatably mounted in a direction substantially parallel to a longitudinal axis of the nacelle capable of alternating between a closed position in which it ensures the aerodynamic continuity of the nacelle and covers the diversion means  40 , into an open position in which it opens a passage in the nacelle and uncovers the diversion means  40 , said cowl  30  also being extended by at least one jet pipe nozzle section  60  aiming to channel the discharge of the cold flow, mounted at a downstream end of said cowl  30 . 
         [0046]    This jet pipe nozzle  60  may supplement a primary jet pipe nozzle channeling the hot flow and is called secondary jet pipe nozzle. 
         [0047]    As illustrated in  FIG. 1 , the downstream section  2  also comprises a front frame  50  extended downstream by the cowl  30 . 
         [0048]    The front frame  50  comprises an element (not shown) called a conical shell designed to ensure support between the front frame  50  and the fan case  3  and middle section  1  of the nacelle, respectively. 
         [0049]    This shell may enable fire resistance. 
         [0050]    The front frame  50  also comprises a diversion edge element  51  ensuring the aerodynamic line with the fan case  3  during reversed jet operation. 
         [0051]    At least these two elements form the front stationary part of the front frame  50 . 
         [0052]    In one non-limiting example of the present disclosure, the upstream portion of this front stationary portion comprises traditional fastening means (not shown) for fastening to the fan case  3 , of the blade connection type with an upside down U-shaped cross-section allowing housing in a groove formed by the fan case  3 . 
         [0053]    The front stationary portion of the front frame  50  is also designed to provide support, on the one hand for the middle section  1  of the nacelle using discrete fittings  52  placed between the diversion means  40  and, on the other hand, actuating means of the cowl  30 , as will be seen later. 
         [0054]    A sealing device  4  is also placed at the interface between the diversion edge  51  of the front frame  50  and the upstream portion of the cowl  30 . 
         [0055]    In reference to  FIG. 2 , in a second form, the fittings are eliminated between the front stationary portion and the middle section  1  of the nacelle, and they are replaced by support bars  53  extending along the longitudinal axis of the nacelle secured to the diversion means  40  and placed between two elements of the diversion means  40  to serve as sliding support for the middle section. 
         [0056]    In reference to  FIG. 1 , the diversion means  40  comprises a plurality of cascade vanes  41 , the front frame  50  also comprises a structural element  54  designed to support the cascade vanes  41  housed, in the retracted position, partially in the thickness of the cowl  30 , when the latter is in the closed position, and partially in the thickness of the middle section  1 . 
         [0057]    The cascade vanes  41  divert the cold flow from the tunnel  12  through the reversal chamber uncovered after downstream translation of the cowl  30 . 
         [0058]    The support element  54  of the front frame  50  is placed upstream of the vanes  41  in the thickness of the middle section  1 . 
         [0059]    The cascade vanes  41  supported by this support element  54  are also extended by a rear frame  55  housed inside the thickness of the cowl  30 . 
         [0060]    The support element  54  as well as the diversion means  41  are attached to a stationary structure (not shown) using rails and guideways connected to the mast of the turbojet engine or the other half-reverser. 
         [0061]    The rear frame  55  is fastened upstream of the jet pipe nozzle  60 . 
         [0062]    In non-limiting examples of the present disclosure, the support element(s)  54  of the front frame  50  and the rear frame(s)  55  are rings or ring sections. 
         [0063]    The cowl  30  comprises an outer shroud  31  and an inner shroud  32  that is present in the continuation of the front frame  50 . 
         [0064]    The outer shroud  31  is connected to the inner shroud  32  using fittings  33  passing through two adjacent cascade vanes  41 , as illustrated in  FIG. 4 . 
         [0065]    In its open position in which it opens a passage in the nacelle and uncovers the diversion means  40 , the cowl  30  allows the secondary flow of the turbojet engine to at least partially escape, said flow portion being reoriented toward the front of the nacelle  1  by the cascade vanes  41 , thereby generating a counter-thrust able to assist the braking of the aircraft. 
         [0066]    In order to increase the portion of the secondary flow passing through the vanes  41 , the inner shroud  32  of the cowl  30  comprises a plurality of reverser flaps  34 , distributed over its circumference and each mounted pivoting by one end around a hinge pin, on the cowl  30  sliding between a retracted position in which the flap  34  closes the opening and ensures the inner aerodynamic continuity of the tunnel  12 , and a deployed position in which, in the reverse thrust situation, it at least partially covers the tunnel  12  in order to divert the cold flow toward the vanes  41 . 
         [0067]    Such an installation may traditionally be done using a set of link rods ending, if necessary, with a spring blade in order to accommodate the various machining allowances and apply a closing force on the flap. 
         [0068]    During the direct thrust operation of the turbojet engine, the sliding cowl  30  forms all or part of the downstream section  2  of the nacelle, the flaps  34  then being retracted in the sliding cowl  30 , which covers the vane passage  41 . 
         [0069]    During a phase for varying the cross-section of the jet pipe nozzle  60 , the reverser flaps  34  may remain in the retracted position, like the cowl  30 . 
         [0070]    To reverse the thrust of the turbojet engine, the sliding cowl  30  is moved in the downstream direction into the open position, and the flaps  34  pivot into the position covering the tunnel  12  so as to divert the cold flow toward the vanes  41  and form a reversed flow guided by the vanes  41 . 
         [0071]    Furthermore, as previously mentioned, the sliding cowl  30  has a downstream side forming the exhaust jet pipe nozzle  60  aiming to channel the discharge of the cold flow, said jet pipe nozzle  60  being partially housed in the thickness of the cowl  30 . 
         [0072]    The jet pipe nozzle  60  thus comprises, at both ends thereof, first  61  and second  62  covering panels ensuring covering between the jet pipe nozzle  60  and the outer shroud  31  and inner shroud  32 , respectively, of the cowl  30 . 
         [0073]    The first covering panel  61  covers the inner portion of the outer shroud  31  of the cowl  30 , in the thickness of the cowl  30 . 
         [0074]    The second covering panel  62  comprises an upstream acoustic panel partially covering the inner portion of the inner shroud  31  and, more particularly, the inner acoustic panel thereof. 
         [0075]    Sealing means  64  are placed between the second covering panel  62  and the inner shroud  32 . 
         [0076]    The interfaces of the covering panels  61 ,  62  of the jet pipe nozzle  60  with the outer shroud  31  and the inner shroud  32  of the cowl  30  are parallel to the longitudinal axis of the nacelle. 
         [0077]    The optimal section of this exhaust jet pipe nozzle  60  may be adapted as a function of the different flight phases, i.e. the takeoff, ascent, cruising, descent, and landing phases of the aircraft. 
         [0078]    The variation of this section, illustrating the variation of the cross-section of cold flow tunnel  10 , is done by partially translating the jet pipe nozzle  60 . 
         [0079]    The jet pipe nozzle can thus be moved into a position varying the cross-section of the jet pipe nozzle  60 , i.e. at least one position decreasing the cross-section of the jet pipe nozzle and a position increasing the cross-section of the jet pipe nozzle. 
         [0080]    The transition from one position to the other of the jet pipe nozzle  60  is commanded by actuating means dedicated to the jet pipe nozzle  60  capable of activating the movement of the jet pipe nozzle  60  toward a position causing the cross-section of the jet pipe nozzle  60  to vary. 
         [0081]    Other actuating means can activate the reversible movement of the cowl  30  between its different positions. 
         [0082]    In fact, advantageously, the exhaust jet pipe nozzle  60  and the cowl  30  move independently of one another. 
         [0083]    The actuating means mentioned will be described in more detail hereafter in reference to  FIGS. 5 to 7 . 
         [0084]    According to the present disclosure, at least part of the front frame  50 , the cascade vanes  41  and the jet pipe nozzle  60  forming a first moving assembly can be axially translated along the longitudinal axis of the nacelle in relation to the cowl  30  in a movement toward a position varying the cross-section of the jet pipe nozzle  60 . 
         [0085]    More specifically, the support element  54  of the vanes  41 , the cascade vanes  41  and the rear frame  55  are able, on the one hand, to slide in concert with the jet pipe nozzle  60  between its positions varying the outlet cross-section of the jet pipe nozzle  60  while the cowl  30  remains stationary and, on the other hand, to move away from the cowl  30  when the cowl  30  is moved toward an open position during thrust reversal. 
         [0086]    In thrust reversal, a second moving assembly is then translated comprising the reverser flaps  34  and the cowl  30 , i.e. the inner shroud  32  and the outer shroud  33 , so as to uncover the cascade vanes  41  and pivot the reverser flaps  34  in the tunnel  12 . 
         [0087]    The interface between the front frame  50 , the cascade vanes  41 , the middle section  1  and the case  3 , making it possible to ensure the described movements, provides an extension structure  42  extending the cascade vanes  41  in the upstream portion thereof and secured to the support element  54 . 
         [0088]    This extension structure  42  has a generally rectangular cross-section similar to that of the support element  54  of the vanes  41 . 
         [0089]    The dimensions of the extension structure  42  are adapted to make it possible to place the support element  54  of the front frame  50  upstream of the fittings  52  passing through the cascade vanes  41  when the first moving assembly is moved into a position varying the cross-section of the jet pipe nozzle  60  and, more particularly, toward a position corresponding to an increase of the jet pipe nozzle  60 . 
         [0090]    In one alternative form, the extension structure  42  may also comprise stop means in order to ensure a reaction of forces between the support element  54  and the stationary part of the front frame  50  beyond a position corresponding to a position of the jet pipe nozzle  60  allocated to a maximum increase in the cross-section of the jet pipe nozzle  60 . 
         [0091]    The present disclosure, which proposes a first moving assembly comprising the support element  54 , the cascade vanes  41 , the rear frame  55  and the jet pipe nozzle  60  for the phases varying the cross-section of the jet pipe nozzle, and a second independent moving assembly comprising the cowl  30  during thrust reversal phases, offers many advantages. 
         [0092]    Thus, the translation of the diversion means  40  offers the advantage of maximizing the available space for the vanes. 
         [0093]    Furthermore, the first moving assembly as previously defined makes it possible to arrange the latter further upstream, which makes it possible to reduce the thickness of the cowl  30  and free space to draw aerodynamic lines that increase the passage section for the flow of air. 
         [0094]    An additional space is thus available for the secondary tunnel. 
         [0095]    This increase in the passage section reduces the flow speed in the tunnel and the associated aerodynamic losses. 
         [0096]    Regarding the movement of the two moving assemblies during the phases for varying the cross-section of the jet pipe nozzle  60  and during thrust reversal phases, two independent actuating systems can be considered or a single actuating system capable of independently performing the movement of the first moving assembly and the second moving assembly, for example such as a telescoping jack. 
         [0097]    These actuating means may be any suitable known actuating means comprising at least one hydraulic, pneumatic, or electric linear actuator or motorized ball screw spindles. 
         [0098]    The actuating means are illustrated in  FIGS. 5 to 7 . 
         [0099]    Regarding the movement of the cowl  30 , at least one actuating jack  70  suitable for reversibly moving the cowl  30  in the downstream direction without driving the jet pipe nozzle  60  or the support element  54  with the vanes  41  is placed under the surface producing the pressure barrier of the tunnel between two reverser flaps  34 . 
         [0100]    The body  71  of the jack  70  is fastened at an upstream end to the fan case  3  or the stationary portion of the front frame  50 , while an inner rod  72  is fastened to the inner shroud  32  of the cowl  30 . The body  71  of said actuator overflows into the thickness of the middle section  1  of the nacelle. 
         [0101]    Regarding the movements of the first moving assembly, at least one actuating jack  80  suitable for reversibly moving the jet pipe nozzle  60 , the support element  54 , the vanes  41  in the downstream direction is placed between two adjacent cascade vanes  41 . 
         [0102]    The body  81  of the cylinder  80  is fastened at an upstream end to a fitting  52  connecting the diversion edge of the front frame  50  to the middle section  1  or directly to the stationary portion of the front frame  50  using a fitting (not shown), while an inner rod  82  is fastened to the rear frame  55 . 
         [0103]    During thrust reversal phases, the jacks  70 ,  80  may be deployed at the same speed or with a differential movement and offset kinematics, or ideally the jet pipe nozzle  60  will have been positioned beforehand in its withdrawn position (position corresponding to the phases where thrust reversal may be requested). 
         [0104]    In that case alone, the jack  70  must be actuated to command the thrust reversal. 
         [0105]    Furthermore, a rail/guideway assembly known by those skilled in the art may be placed between the two moving assemblies, and more particularly between the outer shroud  31  and the first covering panel  61  of the jet pipe nozzle  60 , in order to assist the relative sliding thereof. 
         [0106]    In reference to  FIGS. 3   a ,  3   b  and  3   c , the operating principle of the thrust reversal device  20  described is as follows. 
         [0107]    In direct jet illustrated in  FIG. 3   a , the jet pipe nozzle  60  is in the cruising position, i.e. ensuring the aerodynamic continuity of the cowl  30 , and the cowl  30  is in a closed position ensuring aerodynamic continuity with the middle section  1  of the nacelle. 
         [0108]    The support element  54  and the cascade vanes  41  are in their extreme upstream position, i.e. maximally housed in the thickness of the middle section  1 . 
         [0109]    When varying the cross-section of the jet pipe nozzle  60  as illustrated in  FIG. 3   b , and more particularly when the cross-section of the jet pipe nozzle  60  is increased, the jet pipe nozzle  60  is translated downstream, causing an increase in the outlet cross-section. 
         [0110]    At the same time, the support element  54 , the vanes  41  and the rear frame  55  also move in the downstream direction, until the support element  54  comes into contact with the fittings  52  of the front stationary part of the front frame  50 , the extension structure  42  of the vanes  41  making it possible to position that support element  54  immediately upstream of the fittings  52  passing through the vanes  41 . 
         [0111]    The reverser flaps  34  retain their position ensuring aerodynamic continuity of the inner cowl  32  with the fan cowl  3 . 
         [0112]    During thrust reversal, the first moving assembly is translated maximally downstream, in order to position the vanes  41  in their reverse jet positions, i.e. their position in which the support element  54  is immediately upstream of the fittings  52  passing through the vanes  41 . 
         [0113]    The cowl  30  is translated axially downstream of the nacelle into a position in which it uncovers the cascade vanes  41 . 
         [0114]    In that position, the fittings  33  connecting the inner shroud  32  and the outer shroud  31  of the cowl  30  are found immediately upstream of the rear frame  55  of the cascade vanes  41 . 
         [0115]    During translation of the cowl  30  in the downstream direction of the nacelle, the reverser flaps  34  are gradually deployed in the cold flow tunnel  12  in order to reorient the cold flow of the tunnel  12  toward the uncovered vanes  41  in the upstream direction of the nacelle. 
         [0116]    In  FIG. 3   c , the cowl  30  is completely open and the thrust reverser device  20  is fully activated. 
         [0117]    One alternative form of the present disclosure proposes establishing axial contact to react the forces of the outer shroud  31  by the front stationary portion of the front frame  50  using a set of stops, in order to transmit the axial forces undergone by the vanes  41  directly to the stationary part of the front frame  50  without passing through the jacks  80 . 
         [0118]    The invention is of course not limited solely to the various forms of the nacelle and methods described above as examples, but on the contrary encompasses all alternatives thereof.