Nacelle air intake and nacelle comprising such an air intake

An air intake for a nacelle of an aircraft engine includes a substantially cylindrical outer wall, a substantially cylindrical inner wall, a front lip, a front mounting flange, and a support structure. The front lip connects the substantially cylindrical inner wall and the substantially cylindrical outer wall. The front mounting flange is configured to cooperate with a rear flange of a wall of the aircraft engine forming a fan casing. The support structure comprises a lower end configured to be secured to the fan casing, by the rear flange, and an upper end in contact at least with a downstream portion of the outer wall. The support structure includes access apertures configured to be crossed by maintenance tools during operations of maintenance of the air intake.

FIELD

The present disclosure relates to an aircraft propulsion unit comprising a nacelle and an engine such as a turbojet engine, and concerns in particular an air intake of such a nacelle.

BACKGROUND

An aircraft is propelled by one or several turbojet engine(s) each housed within at least one nacelle. In general, the nacelle has a tubular structure comprising an air intake section upstream of the turbojet engine, a middle section configured to surround a fan of the turbojet engine, and a downstream section accommodating the thrust reversal means.

The downstream section of the nacelle surrounds the gas generator of the turbojet engine which terminates in an ejection nozzle located downstream of the turbojet engine.

In particular, the air intake section of the nacelle includes a front lip with an annular general shape which intercepts the intake air stream of the nacelle which is directed towards a fan.

For this purpose, the rest of the air intake structure has a substantially annular structure comprising an outer panel or wall providing the outer aerodynamic continuity of the nacelle and an inner panel or wall providing the inner aerodynamic continuity of the nacelle, in particular with the fan casing at the level of the middle section. The air intake lip provides the junction between these two walls forming a leading edge of the nacelle and could in particular be integrated to the outer and/or inner panel thereby forming a main wall of the air intake.

In general, the front lip is constituted by one single annular-shaped part which is directly fastened on support partitions internal to the nacelle. Also, it should be noted the use of an upstream partition which forms an annular volume behind the “D”-like shaped front lip.

More specifically, the nacelle intake section generally includes: an inner wall, preferably provided with a substantially cylindrical inner acoustic part having an upstream edge and a downstream edge, this part forming at least one portion of an acoustic shroud of the air intake being called “inner barrel;” a substantially cylindrical outer wall; a front lip connecting the inner and outer walls forming a leading edge; a downstream mounting flange configured for mounting of the intake section to a front flange of a wall of the turbojet engine; and a rear partition having a downstream end to secure the outer portion of the outer wall to the downstream mounting flange.

Moreover, the air intake generally comprises a deicing system. A known type of deicing or anti-icing system, disclosed in particular by the documents EP 0 913 326 B1 or U.S. Publication No. 2002/0179773 A1, includes a circular tube surrounding the nacelle, which feeds in hot air sampled on the turbojet engine, the internal volume of the front lip of this nacelle in order to heat up its walls.

The extension of the front lip of the nacelle is desired in particular for aerodynamic reasons, in order to extend the laminar air flow area downstream. But its extension is not without impact on the design of the rest of the nacelle. In particular, the nacelle should have mechanical rigidity performances so as to reduce its deformations when subjected to the operating loads.

This results in the part that forms the front lip which limits the fresh air intake of the nacelle has a complex shape and large dimensions when viewed in section.

To address these issues, the concept of a so-called “extended” lip has been developed comprising an outer wall extending far downstream with respect to the inner wall and externally covering a portion of the fan casing. The outer wall as well as the lip forming an integral part, that is to say made in one-piece.

Such an arrangement described in the state of the art allows for savings in the material mass and in the complexity of the parts in comparison with the older state of the art wherein the outer envelope and the front lip of the intake section of the nacelle are constituted by separate parts.

However, for these arrangements to be advantageous, additional annular reinforcements are used and disposed inside the outer envelope. Moreover, the unique part formed in this manner has a large dimension and a considerable volume and thus generally requires a complex and expensive tool.

Yet, the solution of a lip integral with the outer wall of the intake section of the nacelle also encounters issues of adaptation to other requirements.

Among these, mention may be made in particular of the maintenance issue. Indeed, in order to inspect the different systems such as the de-icing or to inspect the condition of the structure, access to the space comprised between the front (or upstream) and rear (or downstream) partitions, which is then inaccessible if the part forming the lip and the outer wall are made in one-piece, should be provided for.

SUMMARY

The present disclosure provides a solution having the advantages in terms of aerodynamism of a so-called extended lip while providing an improved maintenance.

The present disclosure provides an air intake for a nacelle of an aircraft engine. The air intake comprises a front lip connecting a substantially cylindrical inner wall and a substantially cylindrical outer wall, and a front mounting flange configured to cooperate with a rear flange of a wall of the turbojet engine. The air intake further comprises a support structure extending from a lower end configured to be secured to a fan casing, at the level of the rear flange, up to an upper end in contact at least with a downstream portion of the outer wall of the air intake. The support structure comprises access apertures configured to be crossed by maintenance tools during the operations of maintenance of the air intake.

Thanks to such a combination of features, the effort path is improved between the air intake and the nacelle, in particular with the rear flange of the wall of the turbojet engine of the fan casing at the level of which the support structure is configured to be secured.

Referring to the support structure, by the expression “secured,” it should be understood that the support structure is configured to be secured to the wall of the turbojet engine forming the fan casing so that a force take-up path, in the assembled position, passes from the outer wall towards the fan casing, without passing through the inner wall.

According to one form, the support structure is directly fastened to the rear flange of the wall of the turbojet engine forming the fan casing.

Moreover, accessibility to the fasteners of the air intake on the fan casing is preserved thanks to the access apertures which facilitate maintenance, in particular after deposition and opening of the fan external cowls.

According to another form, the air intake lip may be integrated to the inner and/or outer wall.

According to yet another form, the air intake lip could be integrated to the inner and/or outer wall so as to form together a wall in one-piece. In other words, the air intake lip, the inner wall and the outer wall are formed in one-piece.

Advantageously, the lower end of the support structure is configured to be secured to a rear face of the rear flange. This also assists in improving the effort path and in reinforcing the structure.

According to one form, the lower end of the support structure is directly fastened to the rear face of the rear flange.

According to another form, the front mounting flange and the rear flange are fastened together by fastening means, the support structure being fastened to the rear flange with all or part of these same fastening means. Such a feature allows avoiding the multiplication of the fastening means and therefore saving weight and gaining in design simplicity. Alternatively, these fastening means may be distinct at least partially or completely.

According to yet another form, the support structure is disposed substantially continuously around the wall of the turbojet engine of the fan casing, and comprises for example a partition. Alternatively or complementarily, the support structure is disposed discontinuously around the wall of the turbojet engine of the fan casing, and comprises for example a set of support rods. In this case, a space between two rods may delimit an access aperture for maintenance.

According to one form, the portion of the outer wall which is at least in contact with the upper end of the support structure, at the level of a support surface of said support structure, comprises a downstream end of the outer wall.

According to another form, besides being in contact against a support surface of the support structure, the outer wall is bearing against it and fastened thereto by fastening means. This allows a better strength of the parts given the stresses to which the air intake is subjected.

According to yet another form, the downstream end of the outer wall is configured to support a front end of the fan external cowl, in the assembled position. The support being, in one form, completed by fastening means. In such a configuration, the junction of the downstream end of the outer wall with the support structure is located under the bearing area of the fan external cowl on the outer wall of the air intake. In this case, the downstream end of the outer wall has a cutout sized according to the radial thickness of said fan external cowl so that the two walls successively forming the external aerodynamic line of the nacelle are continuous and flush. Because the junction is located under the bearing area of the fan external cowl, this allows avoiding altering the quality of the lines and the cosmetic appearance (paint) by obvious fasteners. Therefore, the possible fastening means could have larger dimensions and be less numerous.

According to another form, the present disclosure provides a nacelle comprising an air intake including all or part of the aforementioned features.

DETAILED DESCRIPTION

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

The expression “upstream” and “front” will be used indiscriminately to refer to the upstream of the air intake and the expression “downstream” and “rear” will be used indiscriminately to refer to the downstream of the air intake.

As illustrated inFIG.1, a nacelle1according to the present disclosure has a substantially tubular shape according to a longitudinal axis A (direction parallel to X).

The nacelle1comprises an upstream section2with an air intake3, a middle section4surrounding a fan5of an engine6such as a bypass turbojet engine and a downstream section7accommodating a thrust reverser system (not shown), the nacelle being configured to channel the air streams generated by the engine6.

The air intake3is split into two portions, namely, on the one hand, an intake lip31adapted to allow the capture towards the turbojet engine of the air desired to feeding of the fan and of the inner compressors of the turbojet engine and, on the other hand, a downstream structure comprising walls32,33on which the lip is attached and configured to properly channel the air towards the blades of the fan. The set is attached upstream of a casing of the fan belonging to the middle section4of the nacelle1.

In turn, the downstream section7comprises an inner structure8(also called “inner fixed structure” or “IFS”) surrounding the upstream portion of the turbojet engine6, an outer structure (also called “outer fan structure” or “OFS”)9forming the cold stream channel and fixed with respect to the engine, and a movable cowl including thrust reversal means.

The IFS8and the OFS9delimits a flow path10allowing the passage of an air stream12penetrating the nacelle1at the level of the air intake lip31.

The nacelle1includes a top14configured to receive a reactor attachment mast allowing fastening said nacelle1to a wing of the aircraft. For this purpose, said top14includes means for fastening said reactor mast.

In particular, the turbojet engine nacelle hangs to the reactor mast, through a beam at the level of this top.

The nacelle1terminates in an ejection nozzle21.

As illustrated more specifically inFIGS.2to4, the air intake3includes a front lip31forming a leading edge of the nacelle, said lip31connecting a substantially cylindrical inner wall32and a substantially cylindrical outer wall33.

In other words, the air intake3has a substantially annular structure comprising the outer wall33providing the outer aerodynamic continuity of the nacelle1, and the inner wall32providing the inner aerodynamic continuity of the nacelle1, in particular with the fan casing at the level of the middle section4.

The nacelle1comprises an external envelope and an internal envelope, said external envelope including fan cowls flush with the outer wall33providing the outer aerodynamic continuity and said internal envelope including a fan casing flush with the inner wall32providing the inner aerodynamic continuity of the nacelle1.

The air intake lip31provides the junction between these two walls32,33and could in particular be integrated to the inner and/or outer wall thereby forming a main wall of the air intake3formed in one-piece.

The internal envelope of the nacelle1includes an upstream portion (on the side of the air intake3of the nacelle1) having in particular an acoustic shroud and a downstream portion (on the thrust reverser side) comprising the fan casing42. Both upstream and downstream portions are connected by attachment flanges.

More specifically, the air intake3comprises at the level of its inner wall32a front mounting flange34configured to cooperate with a rear flange44secured to a wall of the turbojet engine at its upstream end, in particular of the casing42of the fan5also called engine casing and at the level of its upstream end.

This assembly of the flanges34and44provides fastening of the air intake3with the middle section4. This assembly is completed and secured by fasteners or fastening means45, for example of the screw-nut type.

The outer wall33has a downstream end33′ configured to be positioned in a junction area flush with a front end43′ (FIGS.5and6B) of the fan external cowl43so as to provide the outer aerodynamic continuity of the nacelle.

To maintain some rigidity to the structure, this outer wall33bears against a support surface51(FIGS.2and4) of a support structure50. In one form, the bearing is completed with fastening means35to fasten the support structure50to said outer wall of the air intake3. For example, these fastening means35may consist of fasteners such as screw-nut sets.

This support structure50extends substantially radially across the thickness of the nacelle1and is configured to be secured to the fan casing42, and more particularly secured to the rear flange44, on a rear face thereof, that is to say opposite to a front face configured to cooperate and/or be affixed with a rear face of the front mounting flange34. This assists in improving the effort path.

In other words, the support structure50extends from a lower end configured to be secured to the middle section4, and more particularly of the fan casing42, at the level of the rear flange44, up to an upper end in contact at least with a downstream portion of the outer wall33of the air intake3.

The support structure50is fastened to the rear flange44with all or part of the same fastening means45of the front mounting flange34and the rear flange44.

The support structure50being secured to the rear flange44, on a rear face thereof, the fastening means45such as screw-nut sets crossing successively from upstream to downstream, respectively: the front mounting flange34, the rear flange44and then the lower end of the support structure50.

In accordance with the present disclosure, the support structure50includes access apertures70configured to be crossed by maintenance tools80during the operations of maintenance of the air intake3.

As illustrated inFIG.4, in this form, the support structure50is formed by a plurality of support rods or posts52. The space formed between each of the support rods52forms an access aperture70. In this case, the access apertures are delimited laterally by the two adjacent posts52on the one hand and radially by the rear flange44and the outer wall33.

The support rods52are distributed along the entire circumference of the nacelle1in a relatively homogeneous manner, in particular around the rear flange44, and are distant from each other by a predetermined distance sufficient to improve the structural integrity of the air intake of the nacelle1.

With reference toFIGS.3to5, the downstream end33′ of the outer wall33is located longitudinally upstream of the front mounting flange34. By this configuration, the support structure52has an inclination such that its orientation deviates generally forward of the longitudinal axis of the nacelle as it gets away from the longitudinal axis.

In particular,FIGS.3and5also illustrate the air intakes3according to forms illustrated herein without the support structure50to illustrate the offset of the downstream end33′ of the outer wall33longitudinally upstream of the front mounting flange34.

InFIG.3, there is further illustrated equipment of the air intake3such as a power supply of a system for deicing the air intake secured to the front partition50′ and an engine probe crossing the acoustic attenuation structure60equipping the inner wall32.

According to other forms, the downstream end33′ of the outer wall33may be located longitudinally substantially at the level of the front mounting flange34(FIG.6A), or be located longitudinally substantially downstream of the front mounting flange34(FIG.6B).

By “downstream of the front mounting flange,” it should be understood downstream of the upstream end of the flange, that is to say downstream of a junction plane between the two flanges in the assembled position.

In order to reduce the noise pollution generated by the turbojet engine, at least the inner wall32of the air intake3is equipped with an acoustic attenuation structure60, which is located in the space delimited by the main wall namely the inner wall32, the outer wall33and the front lip31.

This acoustic attenuation structure60is in the form of a panel with a cellular core forming a cellular structure whose pits delimit acoustic cells, the acoustic structure further comprising a solid inner skin providing in particular the mechanical strength of the panel.

In one form, the acoustic structure60is formed of composite materials. It should be understood that other materials could be used. These materials may be manufactured, for example, by thermoplastic molding, or additive manufacturing of aluminum.

The middle section also includes such an acoustic structure equipping in particular at least partially the fan casing42.

The mounting and rear flanges34,44are secured to these respective acoustic structures60.

FIG.7illustrates a detail view of a support structure50according to one form during an operation of maintenance of the air intake3.

In the operation of depositing or repositioning the air intake3off the fan casing42, two solutions are possible depending on the configurations of the rear support of the outer wall33.

In the case where the support of the air intake3by the support structure50is discontinuous around the wall of the turbojet engine of the fan casing (as illustrated in particular inFIG.4), during a maintenance operation, all it needs is to detach the outer wall33off the support structure50, for example by performing at first a deposition of the fan cowls (if these are fastened) or otherwise to open them (if these are movable and/or hinged), and then said outer wall33is detached off the support structure50. The support structure50remains fastened on the fan casing during the deposition of the air intake. The support structure50is arranged so as to form, by its physical configuration, access apertures70configured to be small enough to guarantee the structural integrity of the nacelle and large enough to be crossed by maintenance tools80during operations of maintenance of the air intake3. It is then easy to access both the front mounting flange34and the rear flange44.

Such a support structure50supporting the outer wall33of the air intake3and configured discontinuously around the wall of the turbojet engine of the fan casing is generally dedicated to a fire-free environment, that is to say this nacelle type does not need to locally protect this region of the nacelle from a fire risk.

In the case of the form illustrated inFIG.7, the support structure50comprises a partition which is generally continuous around the wall of the turbojet engine of the fan casing. In particular, it allows a thermal sealing compatible with a fire protection in order to provide the protection of a possible piece of equipment that would be housed within this space. In other words, in the case where the support structure50comprises a partition, said partition may be segmented. In one form, the partition is solid, that is to say continuous, when it provides a fire door function.

In the same manner, during a maintenance operation, all it needs is to detach the outer wall33off the support structure50and keep this support structure50fastened on the fan casing42during the deposition of the air intake3.

The support structure50being continuous, it is configured so as to have access apertures70configured to be large enough to be crossed by maintenance tools80during the operations of maintenance of the air intake3. In this form, an access aperture70is delimited by edges of the partition on the one hand and by the rear flange44on the other hand.

A closure partition of hatch54is also provided to close the access apertures70during the use of the nacelle in order to provide the continuity of the thermal protection, should this be desired.

It is then easy to access both the front mounting flange34and the rear flange44, as illustrated in thisFIG.7in order to allow dismount thereof.

In the case where the support structure50comprises a partition, the partition may be segmented. In one form, the partition is solid when it provides a fire door function.

Such a support structure50of the downstream end33′ of the outer wall33of the air intake directly connected to the fan casing42, rather than to the inner wall33, is particularly advantageous in terms of force take-up. This concept also allows for an easy access for the needs of maintenance of the flanges34,44and of the equipment present in the air intake such as for example the deicing tube.

FIGS.8,9,10and11illustrate perspective views of a support structure50according to different variants of fastening with the outer wall33of the air intake3and of the fan external cowl43.

InFIG.8, there is shown the downstream end33′ of the outer wall33is configured to support the front end43′ of the fan external cowl43and to be fastened thereto, in the assembled position.

This outer wall33bears against the support surface51of the support structure50. This bearing is also completed with fastening means to fasten the support structure50to said outer wall33of the air intake3. For example, these fastening means35may consist of screw-nut sets.

Moreover, the downstream end33′ of the outer wall33has a cutout sized according to the radial thickness of said fan external cowl43so that the wall33and the cowl43successively form the external aerodynamic line of the nacelle are continuous and flush.

In such a configuration, the junction of the downstream end33′ of the outer wall33with the support structure50is located under the bearing area of the fan external cowl43on the outer wall33of the air intake3. This allows avoiding altering the quality of the lines and the cosmetic appearance by obvious fasteners. Therefore, the possible fastening means could have larger dimensions and be less numerous.

In the configuration illustrated inFIG.9, the front end43′ of the fan external cowl43is directly bearing and fastened together with the downstream end33′ of the outer wall33.

According to another variant, the respective ends33′,43′ of the outer wall33and of the fan external cowl43may be adjoined and supported directly on the support surface51of the support structure50(FIGS.10and11).

In this case, the fastening means35allow fastening the downstream end33′ of the outer wall33with the support structure50and the front end43′ of the fan external cowl43may be simply bearing (FIG.10) or fastened similarly with the support structure50(FIG.11).

It should be noted that the respective ends33′,43′ of the outer wall33and of the fan external cowl43may also rest on an intermediate part or are fastened thanks to this intermediate part which rests on the support surface51of the support structure50.

The present disclosure is described in the foregoing as an example. It goes without saying that those skilled in the art could carry out different variants of the present disclosure yet without departing from the scope of the present disclosure.