Abstract:
The present disclosure relates to a turbojet engine nacelle having an external cowling with an internal wall defining, with an internal fixed structure, an annular flow channel for a secondary airflow and an exhaust nozzle for said secondary airflow. The nozzle includes at least one opening, at least one continuous downstream end portion, downstream of said opening, and at least one door moving between a closed position and an open position allowing the passage of a part of said airflow through said opening. The nacelle is notable in that it includes a shaped device for activation of the door, during their activation from a closed position to an open position of the door, to drive the door in a combined movement that is translational in the direction running upstream from the nacelle and rotary towards the exterior of the nacelle.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a continuation of International Application No. PCT/FR2015/051323, filed on May 20, 2015, which claims the benefit of FR 14/54927, filed on May 30, 2014. The disclosures of the above applications are incorporated herein by reference. 
     
    
     FIELD 
       [0002]    The present disclosure relates to a nacelle for an aircraft turbojet engine comprising a nozzle with downstream doors. 
       BACKGROUND 
       [0003]    The statements in this section merely provide background information related to the present disclosure and may not constitute prior art. 
         [0004]    An aircraft is moved by several turbojet engines each housed in a nacelle. 
         [0005]    A nacelle generally has a tubular structure comprising an air inlet upstream of the turbojet engine, a middle section intended to surround a fan of the turbojet engine, a downstream section accommodating a thrust reverser device and intended to surround the combustion chamber of the turbojet engine, and is generally ended by an ejection nozzle whose outlet is located downstream of the turbojet engine. 
         [0006]    This nacelle is intended to accommodate a bypass turbojet engine able to generate through the blades of the rotating fan a hot air flow (also called primary flow), coming from the combustion chamber of the turbojet engine, and a cold air flow (secondary flow) which circulates outside the turbojet engine through an annular channel, also called flow path, formed between a fairing of the turbojet engine and an inner wall of the nacelle. The two air flows are ejected from the turbojet through the back of the nacelle. 
         [0007]    The thrust reverser device is, during the landing of the aircraft, intended to improve the braking capacity thereof by redirecting forwards at least one portion of the thrust generated by the turbojet engine. 
         [0008]    In this phase, the thrust reverser device obstructs the flow path of the cold air flow and directs the latter towards the front of the nacelle, thereby generating a counter-thrust which is added to the braking of the wheels of the aircraft, the means implemented to perform this reorientation of the cold air flow vary depending on the type of thrust reverser. 
         [0009]    The means implemented to achieve this reorientation of the cold air flow vary depending on the thrust reverser type. However, the structure of a thrust reverser generally comprises movable cowls displaceable between, on the one hand, a deployed position in which they open within the nacelle a passage intended to the diverted flow, and on the other hand, a retracted position in which they close this passage. These cowls may fulfill a function of deflection or simply of activation of other diverting means. 
         [0010]    Furthermore, besides its thrust reversal function, the thrust reverser cowl belongs to the downstream section of the nacelle and has a downstream portion forming the ejection nozzle aiming to channel the ejection of the air flows. 
         [0011]    The optimal section of the ejection nozzle can be adapted depending on the different flight phases, namely the take-off, climb, cruise, descent and landing phases of the aircraft. The advantages already well known of such adaptive nozzles, also called variable section nozzles, are in particular the reduction of noise or the decrease of fuel consumption. 
         [0012]    Among the variable section nozzles according to the prior art, the one described in the patent application published under the number FR 2 622 929, an embodiment of which is represented in  FIG. 1 , is in particular known. This application relates to a nacelle  1  for a turbojet engine, comprising an inner fixed structure  2  and an outer cowling  3  comprising an upstream section  5  and a downstream section  7  comprising a variable geometry nozzle  9 . 
         [0013]    A ring  10  of the downstream section of the outer cowling  3  is slidably mounted axially so as to create an opening  11  in the outer cowling  3 . This opening  11  allows a portion of the air flow  13  circulating in the annular channel  15  to be ejected, which leads to enlarge the section of the nozzle formed by the cowl. 
         [0014]    Although this type of nacelle allows effectively varying the section of the nozzle, it has some drawbacks. 
         [0015]    The mechanical link between the upstream section  5  and the downstream section  7  of the outer cowling  3  constitutes a mechanical weakening of the nacelle. 
         [0016]    Besides weakening the thrust reverser cowl, this mechanical link may also generate vibrations of the annular downstream section of the cowl during the operation of the engine. 
         [0017]    It is also known from the prior art, the variable geometry nozzle  9  described in the patent application published under the number FR 2 946 696, represented in  FIG. 2 , in which the variation of the output section is made through doors  17  movably mounted in rotation between a position according to which they close an opening  19  of the outer cowling  3  and a position according to which they release said opening so as to eject a portion of the secondary air flow  13  to the outside of the nacelle and, consequently, to increase or reduce the output section of the nacelle. 
         [0018]    As represented, this variable geometry nozzle  9  comprises a continuous downstream end portion  21 , downstream of the opening  19  and the doors  17 , which allows substantially increasing the structural strength of the nacelle, and solving the drawbacks of the prior art. 
         [0019]    However, for a significant opening of the door, that is to say for a pivoting of the door  17  important enough (position which is not represented) to allow the passage of a sufficient amount of secondary air flow coming from the annular channel  15 , the air flow which passes through the opening of the outer cowling and which escapes from the nacelle diverges, and is directed in a direction quasi-transverse to the longitudinal axis of the nacelle. 
         [0020]    Such divergence of the air flow greatly affects the aerodynamic profile of the nacelle, and deteriorates the thrust performances of the propulsion assembly. 
         [0021]    Furthermore, the doors of this nozzle have a relatively large and planar trailing edge  23 , which results in a base-drag phenomenon, also affecting the aerodynamic profile of the nacelle and limiting the performances of the nozzle. 
       SUMMARY 
       [0022]    The present disclosure relates to a nacelle for an aircraft turbojet engine comprising:
       an inner fixed structure defining at least partially a fairing of a turbojet engine,   an outer cowling comprising an upstream section and a downstream section, said downstream section comprising an outer wall and an inner wall defining, with the inner fixed structure, an annular flow channel of a secondary air flow, said downstream section comprising an ejection nozzle of said secondary air flow, said nozzle comprising:       
 
         [0025]    at least one opening defined in the downstream section of the outer cowling, 
         [0026]    at least one continuous downstream end portion, downstream of said opening, 
         [0027]    at least one door, acoustically treated or not, alternately movable, upon activation of actuating means, between a closed position closing said opening and providing an aerodynamic continuity of the nacelle, and an open position allowing the passage of at least one portion of the secondary air flow through said opening, from the annular channel toward the outside of the nacelle, 
         [0028]    said nacelle being remarkable in that the actuating means are shaped, upon activation of said means from a closed position to an open position of the door, in order to drive said door into a combined movement in translation upstream of the nacelle and in rotation toward the outside of the nacelle. 
         [0029]    Thus, by providing for actuating means shaped to drive a secondary nozzle door both in translation upstream of the nacelle and in rotation toward the outside of the nacelle, the opening width of the door is limited while satisfying the variation requirements of the output section of the nozzle. 
         [0030]    In other words, such an opening kinematics of the door allows displacing the door in a position which allows redirecting the secondary air flow escaping from the opening of the nacelle to the downstream of the nacelle, in the direction of the longitudinal axis of the nacelle, along the outer wall of the outer cowling of the nacelle. 
         [0031]    Thanks to these kinematics, the rotation angle of the door remains modest; the divergence of the air flow which escapes from the opening is thus limited relative to the prior art, which allows substantially controlling and improving the aerodynamic performance of the nacelle. 
         [0032]    Thus, by making convergent the secondary air flow escaping from the opening provided in the outer cowling of the nacelle, the thrust performances of the propulsion assembly are improved. 
         [0033]    According to optional features of the nacelle according to the present disclosure:
       the actuating means/device comprises:       
 
         [0035]    at least one actuator comprising an upstream body secured to a fixed portion of the nacelle, and a rod whose one end is directly connected to an upstream wall of said door, and 
         [0036]    at least one connecting rod whose one end is connected to the outer cowling of the nacelle and the other end is connected to the door of the nozzle.
       the door comprises a trailing edge shaped to cover at least partially the continuous downstream end portion of the nozzle, which allows defining an aerodynamic continuity of the inner wall and the outer wall of the nacelle at the area between the door and the continuous downstream end portion of the nozzle;   the trailing edge of the door has a curved profile, which allows improving the convergence of the air flow ejected towards the longitudinal axis of the nacelle; the trailing edge of the door has a tapered profile such that a tangent to the lower surface of the door is substantially parallel to the wall of the continuous downstream end portion positioned opposite to the trailing edge of the door, which allows channeling the secondary air flow in a direction substantially parallel to the longitudinal axis of the nacelle, which allows improving the thrust of the propulsion assembly;   sealing means/device is disposed between the door and the outer cowling, and is arranged to oppose the flow of the air on the perimeter of the door and through the opening when the door is in closed position, which allows inhibiting the air circulating in the annular channel from flowing through the door and the associated opening when the door is in closed position;   the door or the outer cowling further comprises at least one fixed or movable lateral flap near the opening;   the upstream section of the outer cowling and the continuous downstream end portion of the nozzle are made in one single piece, which provides a good structural strength of the nacelle;   the door in closed position allows the passage of a controlled leakage rate in the channel in order to obtain a nacelle drag gain;   the nozzle comprises a plurality of openings which are circularly distributed about a longitudinal axis of the nacelle and which are each closed by a door when said door is in its closed position;   the door can be acoustically treated;   a thrust reverser device, equips the nacelle according to the present disclosure.       
 
         [0046]    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 
         [0047]    In order that the 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: 
           [0048]      FIG. 1  illustrates in longitudinal section of a nacelle of the prior art, comprising a variable geometry nozzle comprising a downstream ring movable in translation; 
           [0049]      FIG. 2  represents a longitudinal section of a nacelle according to the prior art equipped with a variable geometry nozzle in which the variation of the output section of the nozzle is performed through doors movable in rotation; 
           [0050]      FIG. 3  is an isometric view which illustrates a propulsion assembly comprising a nacelle according to the present disclosure surrounding an aircraft turbojet engine; 
           [0051]      FIG. 4  represents the nacelle in longitudinal section along the lines A-A and B-B of  FIG. 3 , the door being represented in closed position; 
           [0052]      FIG. 5  is an isometric view of the door, illustrating a variant of the link between the actuator and the door; 
           [0053]      FIG. 6  is an isometric view of the door, centered on its lateral wall, illustrating a link mode between the door and the fixed structure of the nacelle; 
           [0054]      FIG. 7  is a view centered on the door of the nozzle equipping the nacelle according to the present disclosure, the door being represented in closed position; 
           [0055]      FIG. 8  is a cross-sectional view along the line C-C of  FIG. 7 ; 
           [0056]      FIG. 9  represents the nacelle in longitudinal section along the lines A-A and B-B of  FIG. 3 , the door being represented in an open position; 
           [0057]      FIGS. 10 to 13  illustrate the nacelle in longitudinal section along the line A-A of  FIG. 3 , on which are represented four variants of the sealing means/device provided between the door and the outer cowling of the nacelle; and 
           [0058]      FIG. 14  is a view centered on the door of the nozzle equipping the nacelle according to the present disclosure, the door being represented in a closed position and being provided with a lateral flap. 
       
    
    
       [0059]    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 
       [0060]    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. 
         [0061]    It is to be noted that in the description and in the claims, the terms “upstream” and “downstream” should be understood relative to the circulation of the air flow inside the propulsion assembly formed by the nacelle and the turbojet engine, that is to say from the left to the right with reference to  FIGS. 1 to 14 . 
         [0062]    Similarly, the expressions “inner” and “outer” are used, without limitation, with reference to the radial distance relative to the longitudinal axis of the nacelle, the expression “inner” defining an area radially closer to the longitudinal axis of the nacelle, opposed to the expression “outer.” 
         [0063]    Moreover, in the description and the claims, in order to clarify the description and the claims, the longitudinal, vertical and transverse terminology will be adopted, without limitation, with reference to the direct trihedron L, V, T indicated in the figures, whose longitudinal axis L is parallel to the longitudinal axis  29  of the nacelle represented in  FIG. 3 . 
         [0064]    Furthermore, in all the figures, identical or similar references represent identical or similar members or sets of members. 
         [0065]    Referring to  FIG. 3 , on which a propulsion assembly  25  comprising a nacelle  1  according to the present disclosure surrounding a turbojet engine  27  is represented. 
         [0066]    The nacelle  1  is intended to be suspended on an engine pylon (not represented) through a fastening island (not represented) forming a link interface. 
         [0067]    The nacelle  1  comprises an outer cowling  3  comprising an upstream section  5  and a downstream section  7  comprising a variable geometry ejection nozzle  9  of a portion of the secondary air flow circulating in an annular channel  15  defined between the inner fixed structure of the nacelle and the inner wall of the outer cowling. 
         [0068]    The variable geometry nozzle  9  comprises a plurality of openings  19  (one of which is visible in  FIG. 9 ), for example four (only two openings are visible in  FIG. 3 ), circularly distributed around a longitudinal axis  29  of the nacelle. 
         [0069]    Of course, the nozzle can absolutely comprise more than four openings, for example six. It may also (on small diameter nacelles) comprise only two or three openings. 
         [0070]    These openings have each a shape of an open slot radially outwards  31  of the nacelle  1 , and define a passage between the annular circulation channel  15  of the secondary air flow and the outside  31  of the nacelle. 
         [0071]    These openings are each closed by a door  17  alternately movable between a closed position closing its associated opening  19  and an open position allowing the passage through said opening  19  of at least one portion of the secondary air flow, from the annular channel  15  toward the outside  31  of the nacelle. 
         [0072]    In order not to burden the description, only an assembly consisting of an opening  19  and an associated door  17  is described in detail hereinafter, the openings  19  and the associated doors  17  are all similar. 
         [0073]    Downstream of these openings, the variable geometry nozzle  9  has a continuous downstream end portion  21 , made in one single piece with the upstream section  5  of the outer cowling  3 . In other words, the assembly of the outer cowling  3 , further comprising the upstream section  5  and the continuous downstream end portion  21 , is made in one single piece, and the openings  19  are made in this outer cowling. 
         [0074]    With reference to  FIG. 4  illustrating the nacelle  1  seen in longitudinal section along planes respectively passing through the lines A-A and B-B of  FIG. 3 , the door  17  being represented in closed position. 
         [0075]    The door  17  comprises an inner wall  33  and an outer wall  35 . 
         [0076]    The inner  33  and outer  35  walls are immovable relative to each other, which simplifies the design relative to a door comprising an inner skin and a outer skin movable relative to each other. 
         [0077]    The inner and outer walls of the door are structurally linked together by an upstream wall  37 , two side walls  39  and a downstream wall  41  defining a trailing edge  43  of the door  17 . This structure may obviously be reinforced by stringers or inner frames according to the practices known by those skilled in the art. The door  17  can receive an acoustic treatment, for example of sandwich-type. On thin lines, this sandwich can advantageously fill the whole inside of the structure between the walls  33  and  35 . 
         [0078]    When the door  17  occupies its closed position, the inner wall  33  of the door provides an inner aerodynamic continuity of the nacelle, in order not to disturb the flow of the air flow in the annular channel  15 , and the outer wall  35  of the door provides the outer aerodynamic continuity of the fairing of the nacelle. 
         [0079]    The aerodynamic continuity of the inner wall as well as of the outer wall of the cowling of the nacelle, is provided at the junction between the trailing edge  43  of the door and the downstream end portion  21  of the nozzle, thanks to a particular profile of the trailing edge. To this end, the trailing edge  43  of the door has a curved profile  44  advantageously covering an upstream portion  45  of the continuous downstream end portion  21  of the nozzle. 
         [0080]    The trailing edge  43  has a lower surface comprising a downstream portion  47  of a reduced thickness relative to an upstream portion  49  of said trailing edge 
         [0081]    The trailing edge  43  has a tapered profile such that a tangent to the lower surface of the door  17  is substantially parallel to the wall of the downstream end portion  21  positioned opposite the trailing edge of the door. 
         [0082]    In other words, the trailing edge  43  is located in the extension of an outer wall of the outer cowling of the nacelle so as to define an aerodynamic continuity of the outer cowling of the nacelle. 
         [0083]    The door  17  is further likely to be moved by a cylinder-type actuator  51  comprising an upstream body (not represented) secured to a fixed portion of the nacelle, for example the outer cowling of the nacelle, and an actuating rod  53 , whose one free end is directly connected to the upstream wall  37  of the door  17 . This type of actuator, for example electric actuator, is well known to those skilled in the art and therefore will not be further described. 
         [0084]    The rod  53  of the actuator  51  is slidably mounted longitudinally in the associated body along an axis substantially parallel to the longitudinal axis of the nacelle, and the door  17  is pivotally mounted on the end  54  of the rod  53  of the actuator  51 . 
         [0085]    A single actuator is sufficient for the displacement of a door. However, if those skilled in the art find a particular interest therein, several actuators  51  can be connected to the door  17 . Alternatively, a single actuator  51  connected to a movement return device drives a plurality of doors in movement. 
         [0086]    The door  17  is further connected to the outer cowling of the nacelle thanks to connecting rods  55  mounted on the lateral walls  39  of the door  17 . 
         [0087]    Each lateral wall  39  of the door  17  receives two connecting rods  55 , the first one of which is mounted near the upstream wall  37  of the door, and the second one of which is mounted downstream of the first one. 
         [0088]    The disposition of the connecting rods is optimized depending on the kinematics and their structural efficiency. The connecting rods  55  are almost tangent to the inner wall or to the outer wall of the door. This disposition allows better transmitting the forces of the door  17  to the outer cowling  3 . 
         [0089]    According to a variant represented in  FIG. 5 , the end  54  of the rod of the actuator (not represented) can be connected to the door  17  by two connecting rods  56 ,  58  positioned in the continuity of the actuator and forming a “V,” allowing stabilizing the movement of the door  17  and limiting a torsion of the door. 
         [0090]    According to another variant represented in  FIG. 6 , each lateral wall of the door receives three connecting rods  55 . According to this form, two connecting rods forming a “V” are mounted near the upstream wall  37  of the door, and a connecting rod is mounted downstream of the connecting rods forming a “V.” This form allows good stabilization of the movement of the door. 
         [0091]    As represented with more detail in  FIGS. 7 and 8 , to which reference is now made, the connecting rods  55  are substantially tangent to the lateral walls  79  of the door, a first end  57  of the connecting rod  55  is connected to the outer cowling  3  of the nacelle through a link  59 , and a second end  61  of the connecting rod  55  is connected to the lateral wall  39  of the door  17  through a link  63 . 
         [0092]    The door  17  may advantageously be equipped with a lateral sealing means/device provided between the door  17  and the opening  19  associated with the outer cowling  3 , in order to inhibit the lateral, or transverse air leakage, that is to say along a direction perpendicular to the longitudinal axis of the nacelle, between the door  17  and the associated opening  19 , when the door  17  occupies its closed position. 
         [0093]    The lateral sealing means/device in one form comprises a first lateral seal (not represented) interposed between a first longitudinal lateral edge  79  of the door  17  and a first complementary longitudinal lateral edge  81  of the outer wall  65  of the outer cowling  3 . 
         [0094]    By symmetry, the lateral sealing means/device comprises a second lateral seal (not represented) interposed between a second longitudinal lateral edge  85  of the door  17  and a second complementary longitudinal lateral edge  87  of the outer wall  65  of the outer cowling  3 . 
         [0095]    The passage of a door from its closed position represented in  FIG. 4  to its open position represented in  FIG. 9  is described hereinafter. 
         [0096]    The actuator  51  is activated so as to cause a translation upstream of the nacelle of the rod  53 , whose end  54  is connected to the upstream wall  37  of the door  17 . 
         [0097]    Simultaneously with the translation movement of the door to the upstream of the nacelle, the connecting rods  55 , connected to door  17  and to outer cowling of the nacelle, being fixed, causes in concert the rotation of the door  17  to the outside  31  of the nacelle. 
         [0098]    The door  17  moves in one single piece, that is to say, the inner  33  and outer  35  walls of the door pivot about a same instantaneous rotation axis, parallel to an axis connecting the attachment points  59  of the connecting rods on the outer cowling  3  on either side of the nacelle. 
         [0099]    The door  17  is then located in an open position, allowing an escape of a portion of the secondary air flow flowing from the secondary flow to the outside of the nacelle through the opening  19 , as schematically represented by the arrow F, and the output section of the secondary nozzle is thus increased. 
         [0100]    Thanks to the particular door opening kinematics which has just been described, according to which the door is both driven in upstream translation and in rotation, the air flow passing through the opening  19  of the nozzle is advantageously projected downstream of the nacelle, in the direction of the longitudinal axis of the nacelle, along an outer wall  65  of the outer cowling  3  of the nacelle, which allows providing the convergence of the air flow which escapes from the opening  19 , and substantially controlling and improving the aerodynamic performance of the nacelle. 
         [0101]    Furthermore, the curved profile  44  of the trailing edge  43  of the door  17  also improves the convergence of the air flow ejected to the longitudinal axis of the nacelle. 
         [0102]    Reference now is made to  FIGS. 10 to 13  illustrating the nacelle in longitudinal section along the line A-A of  FIG. 1 , on which are represented four variants of sealing means disposed between the door  17  and the outer cowling  3  of the nacelle in order to inhibit the air circulating in the annular channel  15  from flowing through the door  17  and the associated opening  19  when the door  17  is in closed position. 
         [0103]    Referring to  FIG. 10 , the door  17  is equipped with an upstream seal  67  and a downstream seal  69 , both formed of elastomeric material, forming the sealing means/device between the door  17  and the associated opening  19  of the outer cowling  3 , when the door  17  occupies its closed position. 
         [0104]    To this end, the upstream seal  67 , for example bubble or lip seal, is interposed between an upstream end portion  71  of the outer wall  35  of the door  17  and the outer wall  65  of the outer cowling  3 . The upstream seal  67  may indifferently be supported by the door  17  or by the outer cowling  3 . 
         [0105]    Similarly, the downstream seal  69 , for example flat seal, is interposed between the outer wall  35  of the door and the outer wall  65  of the outer cowling. The downstream seal  69  is supported by the door  17  so as not to disturb the flow upon the opening thereof. 
         [0106]    Alternatively, the seal  69  comprises reinforcements arranged so as to allow a straightening of the seal towards the inner face of the door upon its opening. This allows a good redirection of the air flowing at the trailing edge  43  of the door while providing for a tapered profile of the trailing edge. 
         [0107]    In this form, the seal  69  is then forced by elasticity to align with the outer skin of the continuous downstream end portion  21  when the door moves from its open position to its closed position. The seal advantageously constitutes an excellent aerodynamic smoothing seal of the junction area between the door  17  and the continuous downstream end portion  21 . 
         [0108]    Referring to  FIG. 11 , the sealing of the door  17  is provided, on the one hand, by the previously described seals  67  and  69  and, on the other hand, by a second downstream seal  73 , also formed of an elastomeric material, for example, bubble or lip material, interposed between the downstream wall  41  of the door  17  and the upstream portion  45  of the continuous downstream end portion  21  of the nozzle of the outer cowling  3 . 
         [0109]    Referring to  FIG. 12 , the sealing of the door  17  is provided, on the one hand, by the seal  67  and, on the other hand, by a downstream seal  75  formed of an elastomeric material. 
         [0110]    The downstream seal  75  is integrated in the wall of the continuous downstream end portion  21  so as to limit the aerodynamic disturbance when the door is open, and to accommodate the shape of the trailing edge  43  of the door when the latter sinks into the seal  75  when the door  17  is in closed position. The downstream seal  75  can equally be supported by the door  17  or by the outer cowling  3  by adapting its shape to these two different cases. 
         [0111]    Finally, referring to  FIG. 13 , the sealing of the door  17  is provided by the upstream  67  and downstream  73  and  75  seals. 
         [0112]    The downstream seal  75  is advantageously prestressed when the door  17  is in closed position and is deformed inwardly upon the opening of the door in order to align the secondary air flow passing through the opening  19  as parallel as possible to the outer wall  65  of the downstream end portion  21  of the outer cowling  3 , while reducing the base drag at the trailing edge  43  of the door  17  when said door is in open position. 
         [0113]    According to a non represented alternative form, no sealing means/device is provided between the trailing edge  43  of the door  17  and the continuous downstream end portion  21 . In this case, contact points adapted in terms of stiffness and thickness are arranged between these two parts or at the interface of the door and of the outer cowling. The channel obtained in this configuration is advantageously convergent and receives the boundary layer of the secondary flow in order to accelerate the outer boundary layer along the afterbody, thus contributing to decreasing the drag of the nacelle. 
         [0114]    Furthermore, in order to inhibit air from flowing through the sides of the door  17 , the door  17  may advantageously comprise rigid lateral flaps  89  arranged on either side of the door  17 , as shown in  FIG. 14 . 
         [0115]    A device of movable lateral flaps connected to the door by ball-joint connections may however replace the rigid lateral flaps  89  fastened on the door. 
         [0116]    The aforementioned flaps contribute to an axial flow of the secondary air flow passing through the opening  19  downstream of the nacelle, which allows improving the thrust performances of the propulsion assembly. 
         [0117]    According to an alternative which is not represented in the figures, the lateral flaps are supported not by the door itself but by the outer cowling. 
         [0118]    As before, it may be planned to connect these lateral flaps to the outer cowling via ball-joint connections so that the lateral flaps are located in a closed position in which they are folded over the door when the door is located in a closed position, and are located in an open position according to which the flaps are deployed along lateral walls of the door when the door moves from its closed position to its open position. 
         [0119]    According to yet another alternative, the lateral flaps are both supported by the door and the outer cowling, which allows benefitting from a smooth aerodynamic surface when the door is in closed position and to inhibit divergent jets when the door is in open position. 
         [0120]    It should be noted that the description has been made in relation to a smooth nacelle, that is to say non-equipped with a thrust reverser device. 
         [0121]    However, the nozzle according to the present disclosure can equip a nacelle provided with any type of secondary flow thrust reversal means, with cascades or doors. 
         [0122]    Such thrust reverser devices are well known to those skilled in the art and will not be further described in the present description. 
         [0123]    In this case, the doors of the nozzle are positioned downstream of the cascades and/or doors of the thrust reverser. When the nacelle is equipped with thrust reversal means, the actuators of the doors of the nozzle and the thrust reverser cowl(s) can be common, or segregated. 
         [0124]    The upstream body of an actuator is mounted on the body  3  surrounding the door  17 . 
         [0125]    In addition, the primary locks are shaped to inhibit a deployment of the thrust reverser regardless of the position of the doors  17 . 
         [0126]    Thanks to the present disclosure, by providing an actuating means/device shaped to drive a secondary nozzle door both in translation upstream of the nacelle and in rotation outwardly of the nacelle, the opening amplitude of the door is limited while satisfying the variation requirements of the output section of the nozzle. 
         [0127]    In other words, such an opening kinematics of the door allows displacing the door in a position which allows redirecting the secondary air flow escaping from the opening of the nacelle downstream of the nacelle, in the direction of the longitudinal axis of the nacelle, along the outer wall of the outer cowling of the nacelle. 
         [0128]    The divergence of the air flow which escapes from the opening is thus limited as compared to the prior art, which allows controlling and substantially improving the aerodynamic performance of the nacelle. 
         [0129]    Thus, by making convergent the secondary air flow which escapes from the opening provided in the outer cowling of the nacelle, the thrust performances of the propulsion assembly are improved. 
         [0130]    Furthermore, the continuous downstream end portion of the nozzle allows substantially increasing the structural strength of the nacelle. 
         [0131]    Finally, the present disclosure is obviously not limited only to the sole forms of this nacelle described above by way of illustrative examples only, but it encompasses, on the contrary, all the variants involving technical equivalents of the means described as well as their combinations if these fall within the scope of the present disclosure. 
         [0132]    The description of the disclosure is merely exemplary in nature and, thus, variations that do not depart from the substance of the disclosure are intended to be within the scope of the disclosure. Such variations are not to be regarded as a departure from the spirit and scope of the disclosure.