VARIABLE SECTION NOZZLE FOR AIRCRAFT NACELLE AND NACELLE FOR AN AIRCRAFT TURBOJET ENGINE INCLUDING SUCH A NOZZLE

The present disclosure provides a variable section nozzle for an aircraft nacelle having a longitudinal axis. The variable section nozzle includes movable doors and at least one displacement device for displacing the movable doors between a reduced section position and a larger position. The movable doors include at least one first guide device and at least one second guide device, each operable to guide the displacement of the doors relative to a fixed structure of the nozzle. The second guide device is disposed downstream relative to the first guide device and each of the first and second guide devices provide a curvilinear path. In one form, the curvilinear paths are substantially circular and define a circular arc.

FIELD

The present disclosure relates to a variable section nozzle for an aircraft nacelle as well as to a nacelle for an aircraft turbojet engine including such a variable section nozzle.

BACKGROUND

An aircraft is driven by several turbojet engines each housed in a nacelle also accommodating a set of ancillary actuation devices relating to its operation and ensuring various functions when the turbojet engine is in operation or shut-down. These ancillary actuation devices comprise in particular a mechanical thrust reverser actuation system.

A nacelle generally has a tubular structure along a longitudinal axis comprising an air inlet upstream of the turbojet engine, a mid-section intended to surround a fan of the turbojet engine, a downstream section which may house a thrust reverser means and intended to surround the combustion chamber of the turbojet engine. The tubular structure is generally ended with an ejection nozzle whose outlet is located downstream of the turbojet engine.

The modern nacelles are intended to accommodate a turbofan engine capable of generating, via the blades of the rotating fan, a hot air flow (also called “main 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 passage, also called “secondary flow path.”

The term “downstream” means here the direction corresponding to the direction of the cold air flow penetrating the turbojet engine. The term “upstream” refers to the opposite direction.

Said secondary flow path is formed by an outer structure, called Outer Fixed Structure (OFS) and a concentric inner structure, called Inner Fixed Structure (IFS), surrounding the structure of the motor itself downstream of the fan. The inner and outer structures belong to the downstream section. The outer structure may include one or more sliding cowl(s) along the longitudinal axis of the nacelle between a position allowing the exhaust of the reverse air flow and a position preventing such an exhaust.

The nacelle ends with a main ejection nozzle comprising, on the one hand, an outer module, also called main flare or outer nozzle, placed in the structural continuity of the IFS and forming a trailing edge of the main ejection nozzle, and on the other hand, an inner module, also called ejection cone, the inner and outer modules together define a flow channel of the main flow exiting the turbojet engine.

The sliding cowl of the outer structure belongs to the rear section and has a downstream side, also called secondary flare, forming the secondary ejection nozzle aiming at channeling the ejection of the secondary air flow. This nozzle provides the major portion of the thrust required for the propulsion by imparting a velocity to the ejection flows. This secondary nozzle may be associated to an actuation system independent or not of that of the cowl allowing varying and optimizing the outlet section of the secondary flow depending on the flight phase in which the aircraft is.

Indeed, in the case of motors with very high bypass ratio, for reasons of aerodynamic optimization in order to ensure a proper operation of the fan and also to optimize the fuel consumption, it is quite advantageous to be able to adjust the section of the cold air flow outlet downstream of the nacelle: it is indeed useful to be able to increase this section during the departure and landing phases, and to reduce it during the cruising phases: this is often referred as adaptive nozzle, or even as “VFN” (Variable Fan Nozzle).

Conventionally, the variation of the outlet section of the cold flow is performed by means of actuators, for example hydraulic or electromechanical, allowing displacing all or part of the outer fairing of the nacelle, and in particular displacing doors, or flaps, forming movable portions relative to a fixed structure, which are rotated about an axis by means of the at least one of said actuators.

The doors of the adaptive nozzle should, in a closed position, be in continuity with a rear cowling, by respecting the inner and outer aerodynamic lines of the nacelle.

In the open position, the doors of the adaptive nozzle, or VFN doors, allow increasing the outlet section, while respecting a maximum opening angle which does not disturb the (convergent) motor thrust, and also a sufficient leakage for the objectives of improving the motor operability, reduction of noise and consumption.

However, the kinematics of such VFN doors provided with this type of mechanism, ensuring their rotation about an axis by means of an actuator, for example of the cylinder type, requiring a large stroke of said actuator because of the translation of the doors and the rotation in order to obtain the desired angle (divergent or convergent flow).

Furthermore, a large stroke of the actuator involves an adapted dimensioning of the outer structure and that of the door, that is to say larger, and consequently more cumbersome.

A possible solution would be to design actuators of small dimensions having a limited stroke. However, this type of mechanism does not allow obtaining a convergence of the flow with a sufficient flow rate for a limited stroke of the actuator.

SUMMARY

The present disclosure relates to a variable section nozzle for an aircraft nacelle having a longitudinal axis, the nozzle comprising doors movable between a reduced section position and a larger section position, and at least one displacement device for displacing each of the doors between said positions, each displacement device including actuators and controls to control the actuators, the nozzle being characterized in that each of the doors comprises at least one first and one second guide device for guiding the displacement of the doors relative to a fixed structure of the nozzle, the second guide device being placed downstream relative to the first guide device, the first and second guide devices being arranged to provide each, at least locally, a substantially curvilinear path.

Such a structure allows, in particular thanks to the guiding of each door in at least two points thereof such that these points are distinct and distant longitudinally relative to each other, to obtain a displacement path of each of said doors which does not interfere with the inner aerodynamic lines of the nacelle. This also allows:

opening and moving the door forward in order to obtain a leakage for the desired air flow rate; and

limiting the angle of the door in order not to exceed an angle value which would generate a divergent flow.

Moreover, the presence of at least two remote guide devices distant longitudinally relative to each other allows countering more effectively the hoop stresses. Indeed, the thinner the thickness of a door is, the more the hoop stresses are to be countered. The presence of two guide devices thus allows providing an improved resistance of the nozzle during its use and using doors of reduced thickness. In the opposite case, with a single guide device, the door should be thicker.

Advantageously, each of the doors is delimited longitudinally, by an upstream edge and a downstream edge, and laterally, by two lateral flanks, each of the doors of the nozzle comprising at least one first and one second guide device at each of the lateral flanks thereof. In this manner, a first guide device is associated to a second guide device, this pair of first and second guide devices equipping each lateral flank of each door. This feature further allows countering more effectively the hoop stresses and reducing the thickness of the doors of the nozzle. This also allows providing a balance of the door during the use thereof and providing a balance of the pressures exerted thereon.

According to a particular technical feature, each door has a thrust center, said thrust center being, during the use of the nozzle, located longitudinally between the first and second guide devices, and in one form is substantially between 30% and 50% of an axial length of the door relative to the upstream edge.

Further advantageously, each of the doors has a center of gravity, said center of gravity being, during the use of the nozzle, located longitudinally between the first and second guide devices, and in one form is substantially between 30% and 50% of the axial length of the door relative to said upstream edge.

In a particular technical configuration, the first and second guide devices comprise at least one rail arranged to slide in at least one slide portion.

It will be noted that the term “rail” should be understood in a broad sense, such that it also covers rollers or bearings guided by tracks forming slides.

Concerning the slides, it will be noted that each guide device may have its own slide guiding the associated rail, or else the rails of the two guide devices might be guided by the same slide, these two rails being shifted longitudinally and being guided during the displacement of the door in different portions of this slide.

In the rest of the description, the terms “first rail” and “first slide rail” or “first slide portion” will refer to the rail and slide or slide portion of the first guide device. Similarly, the terms “second rail” and “second slide” or “second slide portion” will refer to the rail and slide or slider portion of the second guide device.

Still advantageously, the first and second guide devices, in particular the rail thereof, are spaced longitudinally relative to each other by a distance at least equal to ⅖, being 40%, of the axial length of the door taken between the upstream and downstream edges thereof.

According to an advantageous technical feature, the first guide device, in particular the first rail, is positioned longitudinally at a distance between 5% and 15% of the axial length of the door relative to its upstream edge, and in one variation, at a distance between 5% and 10% of the axial length of the door relative to its the upstream edge.

According to another feature, the second guide device, in particular the second rail thereof, is positioned longitudinally substantially between the middle and the downstream edge of the door, and in one variation, at a distance between 50% and 75% of the axial length of the door relative to the upstream edge thereof.

In one form, the paths provided by the first and second guide devices are substantially circular, each substantially describing a circular arc, and in one variation, the path described by the first guide device includes a concave portion oriented inwardly of the nozzle.

A radius of the first path may be selected such that its value is at least equal to twice the maximum thickness of the door, this thickness being measured radially relative to the nozzle, that is to say orthogonally to the longitudinal axis of said nozzle.

In this same case, where the first and second paths, provided respectively by the first and second guide devices, are substantially circular, the slides guiding the displacement of the rails each have a general circular arc shape. In this case, the rails also have a substantially circular arc shape. Such a shape of the rail allows improving the contact pressure of the rail in the associated slide.

According to a particular feature, the paths, a first and a second paths, provided respectively by the first and second guide devices, have a common path center.

In this case, the second path described by the second guide device has a concave portion also oriented inwardly of the nozzle.

Alternatively, in the case where their path centers are distinct, the second path described by the second guide device has a concave portion oriented outwardly of the nozzle. Such a configuration allows in particular a faster opening and closing of the door while respecting the aerodynamic requirements.

According to another particular feature, each of the doors comprises a groove in which is housed a stud secured to a fixed structure of the nozzle so as to form a locking system of said door.

According to an advantageous feature, the lateral flanks of each of the doors extend along a longitudinal direction and are substantially parallel.

Indeed, conventionally, the variable geometry nozzles have doors having substantially trapezoidal shapes. This type of trapezoidal doors has several drawbacks, in particular in that they cannot establish an aerodynamic continuity with the rest of the nozzle and the nacelle in the inactive position and involves the setting-up of complex mechanisms to move these doors.

On the contrary, the use of doors having substantially parallel lateral flanks allow, in particular, making the mechanisms for moving these doors simple and reliable and more simply providing the doors with the aerodynamic continuity, at least locally, of the nozzle.

Still advantageously, the nozzle comprises laterally, on either side of each door, at least one at least one lateral flap providing a lateral sealing to guide the flow when the associated door is driven outwardly of the nozzle. In one form, the lateral flaps are secured to the fixed structure of the nozzle.

The aforementioned terms “fixed” and “movable” are relative to the nozzle itself. It is understood that this fixed structure relative to the nozzle may be a movable structure relative to the nacelle. This is, moreover, the case when the nozzle is carried by a movable thrust reverser cowl.

According to another advantageous characteristic, at least one first and one second guide devices are integrated, together, in a guide structure comprising:

a box intended to be housed in a thickness of the fixed structure of the nozzle and to be fastened thereto by a removable fastening device, the box comprising a lower portion and an upper portion removable relative to each other;

a first portion of the first and second guide devices, carried by the box;

a second portion of the first and second guide devices, arranged to be positioned on the lateral flank of the associated movable door and arranged to movably cooperate with the first portion of the first and second guide devices, respectively; and

an adjustment device of the guide structure, and in one form, the adjustment device comprises at least one first height adjustment shim, in a radial direction of the nozzle, and at least one second width adjustment shim, in a transverse direction of the nozzle, orthogonal to the radial axis.

Such guide structures may be disposed on either side of each of the doors.

The removable fastening device being removable and the box being both housed in the thickness of the fixed structure and composed of two removable upper and lower portions, access to the guide device is then facilitated during maintenance and the aerodynamic drag is also reduced in flight.

Moreover, the refined adjustment of the position of the guide device allows an improved leveling of the associated VFN door with an outer cowling of the nozzle. The aerodynamic lines of the nacelle are thus improved and the aerodynamic drag is further reduced.

Finally, the box being supported by the fixed structure, the movable door is lighter.

According to a particular feature, the removable fastening device pass through, for example, radially relative to the nozzle, at least the lower portion of the box, the upper portion of the box and the height adjustment shim in order to be fixed in a beam of the fixed structure of the nozzle.

In a particular configuration, these fastening devices are screws and/or pegs.

According to another particular feature:

the width adjustment shim is secured to the second portion of the first and second guide devices; and/or

the height adjustment shim is secured to the first portion of the first and second guide devices.

Advantageously, in the assembled position, the upper portion of the box is covered by a cowling. This cowling may be either a portion of the outer cowling of the fixed structure of the nozzle, or a separate part secured by removable linking mechanisms.

In a particular configuration, the first portion of the first and second guide devices comprises slides, also called sheaths or sliding slots. The second portion of the first and second guide devices may, in this case, comprise rails, or pins, arranged to cooperate with said slides.

Moreover, the present disclosure also relates to a nacelle for an aircraft turbojet engine, characterized in that it comprises a variable section nozzle according to any one of the aforementioned features.

Advantageously, the doors of the nozzle are carried by a movable cowl of a thrust reverser, the door being longitudinally framed by an upstream portion of the movable cowl and by a trailing edge of said movable cowl. In other words, in this configuration the doors of the nozzle do not form the trailing edge of the secondary nozzle of the nacelle, that is to say that they do not form the downstream end of the nozzle.

DETAILED DESCRIPTION

In all these figures, identical or similar references refer to identical or similar members or sets of members.

As shown inFIGS. 1 and 2, a nacelle1has a substantially tubular shape along a longitudinal axis X. This nacelle1is intended to be suspended from a pylon2, itself fastened under a wing of an aircraft.

In general, the nacelle1comprises a front or upstream section3with an air inlet lip4forming an air inlet5, a median section6surrounding a fan101of a turbojet engine100and a rear or downstream section7. The downstream section7comprises an inner fixed structure8(IFS) surrounding the upstream portion3of the turbojet engine100, and an outer fixed structure (OFS)9.

The IFS8and the OFS9delimit an annular flow path called “secondary flow path” allowing the passage of a secondary air flow penetrating the nacelle1at the air inlet5.

The nacelle1therefore includes walls delimiting a space, such as the air inlet5or the secondary flow path, into which the air flow enters, circulates and is ejected.

The nacelle1ends with an ejection nozzle10comprising an outer module11and an inner module12. The inner12and outer11modules define a flow channel of a hot air flow exiting the turbojet engine.

The downstream section7of the nacelle further comprises an ejection nozzle13also called secondary nozzle aiming at channeling the ejection of the secondary air flow. This nozzle13provides the major portion of the thrust for the propulsion by imparting a velocity to the ejection flows. In the case where this nozzle13is carried by a movable thrust reverser cowl, this secondary nozzle may be associated to an actuation system independent or not of that of said movable cowl allowing varying and improving the outlet section of the secondary flow depending on the flight phase in which the aircraft is.

FIGS. 3A and 3Billustrate views of a variable section nozzle13of an aircraft nacelle1according to one form of the present disclosure. In these figures, the upstream of the nozzle13is shown on the left, and the downstream of the nozzle13is shown on the right. Thus, in operation, the air penetrates the air inlet5of the nacelle1and exits through the variable section nozzle13. As indicated in the preamble of the present description, it is important to be able to vary the section of the nozzle13, during the different phases of the flight of the aircraft.

In this form, this variation of the outlet section of the nozzle13is obtained by rotating doors P, here four in number, movable about respective axes A, these axes being substantially perpendicular to the longitudinal axis X of the nacelle1.

These doors P are movable relative to a fixed structure14of the nozzle13between a reduced section position (seeFIG. 3A) and a larger section position (seeFIG. 3B).

In the following forms, the reduced section position corresponds to a closed position of the doors P, in which said doors P are positioned in the aerodynamic continuity of the nozzle13. The larger section position corresponds for its part to a position in which the doors P are positioned at a maximum opening.

The fixed structure14of the nozzle13is intended to be fixedly secured to a movable thrust reverser cowl of the nacelle (not shown), this movable cowl being movable in translation relative to a fixed structure of the nacelle.

The doors P of the nozzle13are longitudinally framed by an upstream portion14aand by a downstream portion14bforming a trailing edge. In other words, in this configuration the doors P of the nozzle do not form the trailing edge of the secondary nozzle of the nacelle.

The nozzle13further comprises at least one displacement device15(see for exampleFIGS. 5A and 5B) for displacing each of the doors P between said reduced section and larger section positions. Each displacement device15includes actuators16and controls to control the actuators (not shown). These actuators16are cylinders connected to the doors P by a slider17guided in translation and by a connecting rod18in rotation both relative to the door P to which it is linked and relative to the slider to which it is linked.

Each of the doors is delimited longitudinally, by an upstream edge19aand a downstream edge19b, and laterally, by two lateral flanks20, the connecting rod18being connected to the door P at the upstream edge19athereof.

FIGS. 4, 5A, 5B and 6illustrate guide devices according to a first form of the present disclosure.

In particular,FIG. 4illustrates guide devices21,22of a door P of a variable section nozzle13according to this first form of the present disclosure.

Indeed, each of the doors P comprises at least one first guide device21and one second guide device22for guiding together the displacement of the doors P relative to the fixed structure14of the nozzle13.

The actuators16perform a substantially longitudinal rectilinear stroke do between 50 mm and 100 mm, according to one form. The stroke associated in particular with the connecting rod18and the guide devices21,22allow displacing the door P between its two reduced section positions (seeFIG. 5A) and a larger section position (seeFIG. 5B). In one example, as illustrated in the figures (for example,FIGS. 5A and 5B), the kinematics of the doors P is configured such that:

the door moves from the reduced section position to the larger section position (direction of the opening of the section), when the cylinder is retracted, that is to say when the displacement device15displace the upstream edge19aof the door P upstream; and

the door moves from the larger section position to the reduced section position (closure direction of the section), when the cylinder is deployed, that is to say when the displacement device15displace the upstream edge19aof the door P downstream.

According to the present disclosure, the second guide device22is placed longitudinally along the axis X downstream relative to the first guide device21, the first and second guide devices21,22being arranged to provide each at least locally, at the point of the guided door, a substantially curvilinear path T1, T2.

In this manner, it is possible to design variable section nozzles13having improved kinematics while providing satisfactory stress resistance.

Such an arrangement allows in particular obtaining a displacement path of each of these said doors which does not interfere with the inner aerodynamic lines of the nacelle, this while allowing both opening and moving the door forward to the maximum in order to obtain a leakage for the desired air flow rate and limiting the angle of the door in order to not exceed an angle value which would generate a divergent flow.

Moreover, the presence of at least two guide devices21,22shifted longitudinally relative to each other allow an improved resistance of the nozzle13during its use by counteracting the hoop stresses and using doors of reduced thickness.

It will be noted that these guide devices21,22are not necessarily aligned along an axis parallel to the longitudinal axis X, the fact remains that the second guide device is upstream of the first guide device.

As is the case here, first and second guide devices21,22are disposed, on either side of each of the doors P of the nozzle, such that they are associated in pairs on each side. In other words, each of the doors P of the nozzle13comprises a first guide device21and a second guide device22disposed at each of the lateral flanks20thereof.

In particular, the second downstream guide device22is disposed so as to be generally aligned longitudinally with the upstream guide device21to which it is associated. In particular, this allows more effectively countering the hoop efforts and reducing the thickness of the doors P of the nozzle13while improving their balance and pressures which are exerted thereon during their use.

Contrary to popular belief, the increase in the number of guide devices21,22, and therefore in the mass of the nozzle13is compensated by the decrease in the mass induced by an improved dimensioning of the elements of the nozzle13. Therefore, this allows reducing the mass of the nozzle13thanks to an improved design of the kinematics of the movable doors P.

The balance of the doors P is further improved when each door has:

a thrust center which, during the use of the nozzle13, is located longitudinally between the first and second guide devices21,22,

substantially between 30% and 50% of an axial length L of the door P relative to the upstream edge19a; and/or

a center of gravity which, when using the nozzle13, is located longitudinally between the first and second guide devices21,22, substantially between 30 and 50% of the axial length L of the door P relative to said upstream edge audit19a.

As is the case here, the longitudinal positioning of all first guide devices21for the same door P, and/or for all doors P of the nozzle13, is identical. Similarly, the longitudinal positioning of all second guide devices22for the same door P, and/or for all doors P of the nozzle13, is identical.

More specifically, the first and second guide devices21,22each comprise a rail23arranged to slide in at least one slide portion24. The rail23is here secured to the door P while the slide portions24are each secured to the fixed structure14of the nozzle13. The rails23comprise a plate at their base having orifices adapted so that said rail23is for example screwed laterally to the door P.

In this manner, each door P comprises two first rails23, with a first rail23per lateral flank20, and two second rails23, with a second rail23per lateral flank20.

In this form, the paths T1, T2provided by the first and second guide devices21,22are substantially circular, that is to say that they each substantially describe a circular arc. In particular, the paths T1, T2are here given by the shape of the slides24each describing a circular arc (seeFIG. 4).

The rails23, for their part, might have different shapes, such as an arc or circular arc shape (see for exampleFIG. 6), in spherical shape offering the advantage of being compatible with complex path curvatures, or even a barrel shape.

The shape of the circular arc-shaped rails23is here in particular adapted to the circular arc shape of the slides24. Such a shape of the rail23allows improving the contact pressure of the rail23in the associated slide24.

It will be noted that barrel-shaped rails allow for their part a better adaptability when the slides24delimit or follow a curvilinear path which is not in circular arc-shaped and which has different radii of curvature or that its radius of curvature is not constant.

The first and second guide devices21,22are arranged such that the paths T1, T2that they provide have a common center of path C1, 2, or center of rotation here where the path is circular. This center of rotation C1, 2is located at the secondary flow path. In this manner, the first and second paths T1, T2described by the first and second guide devices21,22each have a concave portion oriented inwardly of the nozzle13.

The position of the first and second guide devices21,22may vary depending on the axial length L of the associated door P taken between its upstream19aand downstream19bedges. Generally, the first and second guide devices21,22are placed at predetermined zones of the door P so that the kinematics is improved while allowing an improved distribution of the forces for a reduced door P dimension.

It will be noted that, generally, the dimensions of the doors P such that their length L or the desired kinematics depend on several factors, including in particular:

the inner and outer aerodynamic lines (especially inner) of the nacelle1and in particular of the nozzle13,

the percentage of increase of the desired outlet section,

the angle of the door P relative to the aerodynamic line, in particular, in the larger section position: this angle should not be too large to avoid disturbances of the outer line, such as for example between 5% and 10% relative to the longitudinal axis X, and in one form is about 7%, and

the width of the door: generally, the smaller the width of the door is, the more significant its length is, and conversely, this for stress resistance reasons in particular.

In particular, in this form, the length L of each of the doors P is comprised between 480 mm and 520 mm.

The first and second guide devices21,22disposed together in pairs on each side of the doors P are disposed such that they are substantially aligned together longitudinally and that their longitudinal spacing E relative to each other is at least equal to ⅖, being 40%, of the length L of the door P. This distance E is here substantially comprised between 235 mm and 260 mm.

The position of the first and second guide devices21,22is also chosen such that in the closed position of the nozzle13:

the first guide device21, in particular the first rail23, is positioned longitudinally at a distance d1substantially comprised between 5% and 10% of the length L relative to the upstream edge19aof the associated door P; and

the second guide device22, in particular the second rail23, is positioned longitudinally substantially between the middle, that is to say at mid-distance between the upstream19aand downstream19bedges, and the downstream edge19bof the associated door P, and in one form positioned at a distance d2between 50% and 75% of the length L relative to the upstream edge19aof the associated door P (seeFIG. 6).

The distances d1and d2are here measured relative to the associated rail23secured to the door. This allows a more accurate position because the slide24should have a larger longitudinal dimension to guide the rail23.

Moreover, in order to further improve the kinematics of the door P during its displacement, the radii R1and R2of the first and second paths T1, T2, each defined by the distance separating the center of path C1,2to the first and second guide devices21,22, and in particular to their respective rail23, are selected such that the radius R1is substantially comprised between 225 mm and 240 mm and the radius R2is substantially comprised between 335 mm and 350 mm. In a more general manner in this form, the radius R2of the second path T2is selected to be greater than the radius R1of the first path T1.

In this manner, and since the center of rotation C1,2of these two paths is the same, the movement of the door P locally at the second downstream guide device22is greater than the movement of the door P locally at the first upstream guide device21and provides the kinematics of the desired door P.

In general, the first and second guide devices21,22are arranged so that said common center of path C1,2is positioned longitudinally between the first and second guide devices21,22.

In this form, the center of path C1,2is located longitudinally at a distance d3between 0 and 20 mm from the first guide device21, in particular from its rail23.

Moreover, the inclination of the first and second rails23, namely the angles formed by the chords associated to each of these first and second rails23relative to the longitudinal axis X of the nozzle and the nacelle1, in which the term “chord” means, the segment joining the ends of the arc formed by each of the rails, varies substantially between −5° and 0° for the first rail23and between 40° and 50° for the second rail23.

Thanks to such a configuration, it is possible to obtain a displacement kinematics of each of the P doors which does not interfere with the inner aerodynamic lines of the nacelle, this while allowing opening and moving the door P forward to obtain a leakage for the desired air flow rate and limiting the angle of the door P in order not to exceed an angle value which would generate a divergent flow.

FIGS. 7A, 7B, 8 and 9illustrate guide devices21,22according to a second form of the present disclosure.

This second form essentially differs from the first form in that the paths T1, T2, provided by the first and second guide devices21,22having centers of path, here of rotation, respectively a first center of path C1and a second center of path C2, which are distinct.

Thus, the first path T1described by the first guide device21has a concave portion oriented inwardly of the nozzle13and the second path T2described by the second guide device22has an opposite concave portion, oriented outwardly of the nozzle13.

The first center of rotation C1associated to the first path T1is always located at the secondary flow path.

Such a configuration allows in particular a faster opening and closing of the door P while respecting the aerodynamic requirements.

In this form the length L of each of the doors P is comprised between 480 mm and 550 mm.

The first and second guide devices21,22for guiding each side of the doors P are also disposed such that their longitudinal spacing E relative to each other is at least equal to ⅖, being 40%, of the length.

In the same manner as in the form shown inFIGS. 4, 5A, 5B and 6, the position of the guide devices21,22is selected such that in the closed position of the nozzle:

the first guide device21, in particular the first rail23, is positioned longitudinally at a distance d1comprised substantially between 5% and 15% of the length L relative to the upstream edge19aof the associated door P; and that

the second guide device22, in particular the second rail23, is positioned longitudinally substantially between the middle, that is to say at mid-distance between the upstream19aand downstream19bedges, and the downstream edge19bof the associated door P, and positioned at a distance d2comprised substantially between 50% and 75% of the length L relative to the upstream edge19aof the associated door P.

The radii R1and R2of the first and second paths T1, T2are here selected such that the radius R1is comprised substantially between 200 mm and 450 mm and the radius R2is comprised substantially between 60 mm and 100 mm.

The first and second guide devices21,22are arranged such that the first center of path C1is positioned longitudinally between the first and second guide devices21,22and such that the second center of path C2is positioned longitudinally between the second guide device22and the downstream edge19bof the door P. In other words, the centers of paths are located longitudinally downstream of the associated guide devices.

The centers of rotation C1, C2distinct from the paths T1, T2provided by the first and second guide devices21,22are spaced relative to each other by a distance d4comprised substantially between 60% and 70% of the length L of the door P (the considered distance d4is here a distance taken in the space and unreported longitudinally).

Moreover, and more generally, the center of rotation C1or C1,2of the first path T1provided by the first guide device21is located:

longitudinally between the first and second guide devices21,22; and/or

longitudinally at a distance d5comprised substantially between 5% and 15% of the axial length L of the door P relative to the upstream edge19athereof.

The nozzle13further includes, for each of its doors P, at least one locking system25which comprises a groove26secured to the door P, or to the fixed structure14, in which is housed a stud27secured to the fixed structure14of the nozzle13, or respectively of the door P.

FIGS. 10, 11, 12 and 13illustrate in particular a door P according to one form of the present disclosure.

In particular, it is particularly seen inFIGS. 10A and 10Bthat the lateral flanks20of the door P extend in the longitudinal direction X and are substantially parallel, at the same time to each other and to the longitudinal axis X. This allows making the movement mechanisms of these doors simple and reliable and more simply providing the doors with the aerodynamic continuity, at least locally, of the nozzle13.

Moreover, the nozzle13has on either side of each of its doors P, a lateral flap28allowing in particular a lateral sealing in order to guide the flow when the associated door P is moved outwardly of the nozzle13.

These lateral flaps28are here secured to the fixed structure14of the nozzle13and have a wall or panel shape raised radially relative to the nozzle13and protruding relative to the outer aerodynamic lines of the nozzle13and thus of the nacelle1. This wall is increasingly protruding relative to the outer aerodynamic lines of the nozzle13from upstream to downstream. These lateral flaps28might be fixed or movable.

FIGS. 14, 15A, 15B, 16, 17A and 17Bshow an example of integration of a first and a second guide devices21,22in an adapted guide structure30, such a guide structure30being located laterally on either side of each of the doors P equipping the nozzle13.

In these figures, the guide devices21,22are those described in relation withFIGS. 5A, 5B and 6except that the rails23do not have here a circular arc shape but a barrel shape (see for exampleFIG. 14).

The guide structure30here comprises:

a box31intended to be housed in a thickness of the fixed structure14of the nozzle13and to be fastened thereto by a removable fastening device32, the box31comprising a lower portion310and an upper portion311removable relative to each other,

a first portion of the first and second guide devices21,22, carried by the box31,

a second portion of the first and second guide devices21,22, arranged to be positioned on the lateral flank20of the associated movable door P and arranged to movably cooperate with the first portion of the first and second guide devices21,22, respectively; and

an adjustment device33of the guide structure30.

The adjustment device33of the guide structure30comprises a first height adjustment shim331, in a radial direction Z to the nozzle, and a second width adjustment shim332, in a transverse direction Y of the nozzle, orthogonal to the radial axis Z, corresponding substantially to a direction tangential to the nozzle13at the first and second guide devices21,22.

The refined adjustment of the position of the first and second guide devices21,22allows an improved leveling of the associated door P with an outer cowling of the nozzle13. The aerodynamic lines of the nacelle1are therefore improved and the aerodynamic drag is reduced.

The first portion of the first and second guide devices21,22, carried by the box31is formed in particular by the slides24of the first and second guide devices21,22while the second portion of the first and second guide devices21,22, arranged to be positioned on the lateral flank20of the associated movable door P and arranged to movably cooperate with the first portion of the first and second guide devices21,22, respectively, is formed in particular by the rails23of these said guide devices21,22, which are therefore arranged to cooperate with the associated slides24.

Even if such a configuration is desired because it allows limiting the mass of the door P, it is not limiting and it might be considered in an alternative form (not shown) that the rails23are secured to the fixed structure14of the nozzle13and the slides24are secured to the door P.

Such a guide structure30allows an improved integration of a first guide device21and a second guide device22at each lateral flank20of each door P of the nozzle13, said guide structure30being here disposed on either side of each of the doors P.

The fastening device32being removable and the box31being both housed in the thickness of the fixed structure14of the nozzle13and composed of two lower310and upper311portions removable relative to each other and in particular here also removable relative to the nozzle13, access to the guide elements is then facilitated during the maintenance. Such a guide structure30also allows reducing the aerodynamic drag during a flight phase.

These removable fastening mechanisms32are here screws passing radially through the lower portion310of the box31, the upper portion311of the box31and the height adjustment shim331in order to be fastened in a beam of the fixed structure of the nozzle13.

Moreover, in this form, the width adjustment shim332is secured to the second portion, that is to say here rails23, of the first and second guide devices21,22. The height adjustment shim331is secured to the first portion, that is to say slides24, of the first and second guide devices21,22. Alternatively, these shims might be independent for each rail23and for each slide24of each of the guide devices21,22.

The adjustment of the leveling of the door P relative to the rear cowl is done here by the addition of shims331in order to limit the clearance.

The guide structure30further comprises, in the assembled position, a removable outer cowling34covering the upper portion311of the box31. This cowling34may be either a portion of the outer cowling of the fixed structure14of the nozzle13, or a distinct part secured by removable linking mechanisms.

As is in particular shown inFIGS. 15A, 15B, 17A and 17B, the rail23of the first guide device21is hinged relative to its support formed here by the lateral flank20of the door. More specifically, the rail23is positioned free in rotation relative to the door P to which it is secured and about a transverse axis Y to the associated lateral flank20.

On the contrary, the rail23of the second guide device22is fastened relative to the fixed structure14of the nozzle13to which it is secured. It is understood that, generally, the rail23may be either hinged, or fastened depending on the kinematics of the desired door P.

The lower portion310of the box31is positioned in the fixed structure14(rear cowl of the nacelle) by a tenon/mortise-type recovery effort system312. The upper portion311of the box31is positioned in the same manner on the lower portion310of said box and in the fixed structure14of the nozzle13.

The box31allows, thanks to its lower310and upper311portions, to sandwich, in one form radially, in the assembled position, the first portion, namely here the slides24, of the first and second guide devices21,22, carried by the box31. Indeed, the lower310and upper311portions of the box31are arranged to be superimposed and to cooperate together, the first portion of the first and second guide devices21,22being interposed between these lower310and upper311portions of the box31.

Such a configuration allows, with the removable fastening device32, facilitating the mounting and dismounting of the guide structure30while providing a stress resistance which is adapted.

The use of the guide structure30is independent of the type of mechanisms (rotary, rail guide, mixture of several solutions, among others) and allows being able to perform a mounting, dismounting and simple adjustment in production and in maintenance.

Such a guide structure further allows proposing a way to house the first and second guide devices21,22in the thickness of the inner and outer aerodynamic lines of the nozzle and the nacelle.

FIGS. 18A, 18B, 18C, 18D and 18Eshow steps of a dismounting method of this guide structure.

A dismounting method of the guide structure30includes the following steps:

a disengagement step of the cowling34;

a dismounting step of the upper portion311of the box31by removing the removable fastening device32;

a dismounting step of the lateral flank20of the door P associated with the first and second guide devices21,22; and

a disengagement step of the lower portion310of the box relative to the fixed structure14of the nozzle13.

A mounting method of the corresponding guide structure30includes these same steps as the dismounting method but performed in a reverse order, that is to say:

a fastening step of the lower portion310of the box to the fixed structure14of the nozzle13;

an insertion step of the lateral flank20of the door P associated with the first and second guide devices21,22;

a fastening step of the upper portion311of the box31via the removable fastening device32; and

a setting-up step of the cowling34.

In the illustrated steps, it will be noted that an upstream portion of the lateral flaps28, located in line with the associated box31, is here secured to the fixed structure14of the nozzle13, but more specifically secured to the upper portion311of the box31and even in one-piece part. This facilitates the dismounting.

These steps might be implemented in order, for example, to add and/or remove adjustment shims331,332to adjust the first and second guide devices21,22.

Such a guide structure30allows providing a mounting, dismounting and an adjustment of a VFN door in a workshop and/or maintenance which is simple, fast and accessible and that in an environment of small thickness for nacelles with very high bypass ratio.

The guide structure30may enclose at least one portion of the first and second guide devices21,22in two lower310and upper311portions of the box31, the whole may be height-adjustable, taking back the efforts mechanically by mortise tenons312and all assembled by bolts32.

An architecture of a nozzle13provided with such guide structures30and their positioning in the upper (at 12 o'clock), lower (at 6 o'clock) and central (at 3 o'clock and 9 o'clock) portions relative to the nozzle13of the nacelle, in the beams140of the fixed structure14of said nozzle13, reduces the growths outside the aerodynamic lines of the nacelle.

The nozzle13according to the present disclosure allows offering a solution implementing a simple kinematics by rail/slide of the door P in rotation and/or translation.

The present disclosure is described in the above by way of example. It is understood that those skilled in the art are able to carry out different variants of the present disclosure without departing from the scope of the present disclosure.