FR3137414A1 - INLET CONE FOR AIRCRAFT TURBOMACHINE - Google Patents

Abstract

The invention relates to an inlet cone (9) for an aircraft turbomachine fan mounted movable in rotation around an axis of rotation (R), comprising an upstream cone (1) fixed by at least one first fixing screw (4) to a downstream ferrule (2), said first fixing screw (4) being configured to be housed in a first threaded orifice (40) formed partly in said upstream cone (1) and in said downstream ferrule (2 ), and opening into a vein (39) dug on said upstream cone (1). According to the invention, the inlet cone (9) also comprises a cover (3) configured to attach to said upstream cone (1) so as to close off said vein (39), the upstream cone (1), the downstream ferrule (2) and said cover (3) jointly forming a substantially continuous external surface of said inlet cone (9). Figure 5

Description

INLET CONE FOR AIRCRAFT TURBOMACHINE Field of invention

The present invention relates to the field of fans for turbomachines, in particular for an aircraft turbojet. More particularly, the invention relates to an inlet cone for such a turbomachine.

State of the prior art

As illustrated in , a state-of-the-art turbomachine comprises at its upstream end an air inlet intended to supply, by means of an air flow F, a fan. This fan comprises a fan disk 104 centered on the axis of rotation R', and fan blades 105 attached to the fan disk 104.

The air flow F entering this turbomachine via the air inlet, in a direction corresponding to the main direction of flow of the gases within the turbomachine, is deflected by an inlet cone towards the blades 105 of the fan, then is separated into a primary flow passing through the compressor supplying the combustion chamber of the turbojet and a secondary flow which flows around the compressor.

This inlet cone is centered on the axis of rotation R' and is driven in rotation with the fan disk. It can for example be made in one piece as illustrated in of document EP2028375. It can also be made in several adjacent parts as illustrated in figures 1 and 2 of document EP2028375, for example with an upstream part 101 coming from the top of the cone, otherwise called upstream cone, and a downstream part 102, otherwise called downstream shroud, adjacent to the fan blades and conventionally carrying balancing weights.

In order to keep the upstream part and the downstream part fixed, and these two parts on the fan disk or on a connecting part to the fan disk, a known technique consists in fixing the upstream cone to the downstream shroud by means of a plurality of screws 106 regularly spaced around the periphery of the cone. These screws, inserted in longitudinal housings 103, or counterbores, however have a major aerodynamic drawback because the housings are visible and cause local turbulence disturbing the incoming air flow.

To counter this drawback, it may be considered to fill the counterbores using tape or silicone in order to preserve aerodynamics, for example during wind tunnel tests prior to putting the turbomachine into circulation.

However, a disadvantage of such a solution is that the operation requires cleaning and drying time each time it is disassembled. This can also create a risk of damage to the inlet cone elements during disassembly.

Furthermore, such a solution can only be temporary and therefore cannot reasonably be used in the context of routine use of turbomachines.

There is therefore a need to improve current solutions in order to improve the aerodynamics of turbomachine inlet cones while avoiding the drawbacks of current solutions.

The invention aims to remedy at least in part the drawbacks mentioned above relating to the techniques of the prior art.

To do this, the invention relates to an inlet cone for an aircraft turbomachine fan mounted to rotate about an axis of rotation, comprising an upstream cone fixed by at least a first fixing screw to a downstream shell, said first fixing screw being configured to be housed in a first tapped orifice formed partly in the upstream cone and in the downstream shell, and opening into a vein dug on said upstream cone.

According to the invention, the inlet cone also comprises a cover configured to be fixed to said upstream cone so as to close off said vein, the upstream cone, the downstream ferrule and said cover jointly forming a continuous external surface of said inlet cone.

Thus, the invention provides a novel and inventive approach to at least partially solving some of the drawbacks of the prior art.

In particular, such a cover closing the vein and having an external surface arranged in the continuity of the upstream cone and the downstream shell makes it possible to limit local turbulence which could disturb the air flow entering the turbomachine. The same is true for the first tapped orifice which is formed opening into a vein dug on the upstream cone, which makes it possible to drown the orifice in the vein so as not to generate rising steps on the external profile of the cone which could also disturb the air flow.

In addition, such a solution makes it possible to integrate fasteners while minimizing their impact on the vein while having a removable system that does not require any specific intervention, whether at the time of installation (drying time, cleaning of the installation area, etc.) or for possible disassembly for maintenance, cleaning, etc.

Furthermore, such a solution implementing mechanically simple and easily dismantled components makes it possible to implement a system that is both simple to use and inexpensive.

According to a particular aspect of at least one embodiment of the invention, the cover has a through hole configured to be positioned opposite a second tapped orifice formed in said vein, and capable of cooperating with a second fixing screw so as to fix said cover on said upstream cone.

This allows for a relatively simple and inexpensive fixing for the cover, while being reliable and easily removable.

According to a particular aspect of at least one embodiment of the invention, said cover has a shape complementary to said vein.

According to a particular aspect of at least one embodiment of the invention, said cover has an oblong shape.

According to a particular aspect of at least one embodiment of the invention, said cover comprises a portion having a substantially oblong shape, extended by a platform having a second height less than the first height, said platform being configured to come and position itself opposite said first tapped orifice.

This makes it easier to position the cover because the platform is configured to position itself opposite said first tapped hole and therefore leaves room for the head of the first fixing screw regardless of its positioning and tightening.

According to a particular aspect of at least one embodiment of the invention, the second tapped hole of the second fixing screw is centered on the first portion.

Such a solution makes it possible to implement relatively simple and inexpensive indexing means, in addition to the two portions which can also act as indexing means.

According to a particular aspect of at least one embodiment of the invention, the second tapped orifice extends along an axis N normal to a direction of extension E of said vein.

According to a particular aspect of at least one embodiment of the invention, the inlet cone further comprises sealing means provided between the periphery of said cover and the contour of said vein.

This allows air circulation to be further limited or even allows for complete sealing so as to limit air disturbances.

The invention also relates to a fan for an aircraft turbomachine mounted to rotate about an axis of rotation R, comprising an inlet cone according to one of the aforementioned embodiments.

The invention also relates to a turbomachine for aircraft comprising a fan according to the aforementioned embodiment.

According to a particular aspect of at least one embodiment of the invention, the turbomachine is a turbojet.

The invention is also feasible for a static cone, such as for certain testing machines.

Presentation of figures

The invention, as well as the various advantages that it presents, will be more easily understood in the light of the following description of an illustrative and non-limiting embodiment thereof, and of the appended drawings among which:

already described, is a schematic sectional side view illustrating a state-of-the-art inlet cone;

represents a schematic view of a dual-flow turbojet engine, in longitudinal section;

is a side sectional view of a portion of the inlet cone according to one embodiment of the invention;

is a perspective view of a portion of the inlet cone according to the embodiment of the ;

is a front perspective view of a portion of the inlet cone according to the embodiment of the ;

is an exploded perspective view of a portion of the inlet cone according to the embodiment of the , the first fixing screw being inserted;

is an exploded perspective view of a portion of the inlet cone according to the embodiment of the , the second fixing screw and the cover being installed;

is a perspective view of a portion of the inlet cone according to the embodiment of the ;

is a front view of a part of a turbomachine according to one embodiment of the invention, and

is a perspective view of a part of a turbomachine according to the embodiment of the .

It should be noted that, throughout the description, the terms “upstream” and “downstream” are to be considered according to the main direction of flow of the gases within the turbomachine, and therefore on their arrival on the external surface of the inlet cone by means of the air flow.

Referring first of all to the , an aircraft turbomachine 901 is shown, according to a preferred embodiment of the invention. This is a twin-spool turbojet engine. However, it could be a turbomachine of another type, for example a turboprop, without departing from the scope of the invention. The turbojet engine 901 has a longitudinal central axis 902 around which its various components extend. It comprises, from upstream to downstream along a main direction 905 of gas flow through this turbojet engine, a fan 903, a low-pressure compressor 904, a high-pressure compressor 906, a combustion chamber 911, a high-pressure turbine 907 and a low-pressure turbine 908.

Conventionally, after passing through the blower, the air is divided into a central primary flow 912a and a secondary flow 912b which surrounds the primary flow. The primary flow 912a flows in a main gas circulation vein 914a passing through the compressors 904, 906, the combustion chamber 911 and the turbines 907, 908. The secondary flow 912b flows in a secondary vein 914b delimited radially outwards by a motor casing, surrounded by a nacelle 909. The compressors 904, 906 and the turbines 907, 908 are produced by alternating moving wheels, called rotor wheels, and fixed wheels, called stator wheels.

The principle of the invention is based on the implementation of an inlet cone comprising a cover configured to close the fixing means between the upstream cone and the downstream ferrule so that the external surface of the inlet cone is substantially continuous.

Such an inlet cone can for example be implemented within a fan for an aircraft turbomachine, which can in particular be an aircraft turbojet.

We will now present, in relation to Figures 3 to 8b, a first embodiment of the invention, given as a simple illustrative and non-limiting example.

As illustrated, the inlet cone 9 comprises an upstream cone 1 fixed by at least one first fixing screw 4 to a downstream ferrule 2.

This first fixing screw 4 is configured to fit into a first tapped hole 40.

In this embodiment, this first tapped orifice 40 extends along an axis substantially parallel to the axis of rotation R of the aircraft turbomachine fan.

As visible in particular in , the first tapped orifice 40 is formed at least partly in the upstream cone 1 and in the downstream ferrule 2 and opens into a vein 39 dug on the upstream cone 1.

More particularly, in this embodiment, the first tapped orifice 40 is drilled mainly in the downstream ferrule 2. It opens into a vein 39 dug on the upstream cone 1 so that once the first fixing screw 4 is housed in the first tapped orifice 40, the screw head is mounted opening into this vein 39.

As illustrated in particular in , the vein 39 extends in a direction of extension E. This direction of extension corresponds substantially to a direction tangent to the external surface of the inlet cone 9 at the level of this vein.

So that the inlet cone 9 has a substantially continuous external surface in order to limit in particular the disturbances of the air flow entering the turbomachine, the inlet cone also comprises a cover 3 configured to be fixed on the upstream cone 1 so as to block the vein 39.

In this way, the upstream cone 1, the downstream ferrule 2 and the cover 3 jointly form a substantially continuous external surface of the inlet cone 9.

In other words, the cover 3 is configured to be fixed flush in the vein 39 so that the upstream cone 1, the downstream ferrule 2 and the cover 3 jointly form a substantially continuous external surface of the inlet cone 9.

It should be noted that, according to an embodiment not shown here, the inlet cone may also comprise sealing means provided between the periphery of the cover and the internal contour of the vein so as to further limit the risks of disruption of the aerodynamic flow and to increase the tightness of the cover against the vein.

These sealing means may, for example, include an O-ring provided around the edge of the cover.

As more particularly visible in figures 6 and 7, the cache 3 here has an oblong shape.

More particularly, here, the cache 3 comprises a portion 30 having a substantially oblong shape, extended by a platform 31 having a second height h2 lower than the first height h1.

In other words, the cover 3 has a total volume whose height is variable. By height, we mean the distance between the surface which comes into contact with the bottom of the vein 39 and the surface which is flush with the external surface of the cone. In this embodiment, the height of the cover 3 varies between a first height h1, corresponding to the height of the platform 31, and a height h2 corresponding to the height of the portion 30. As a result, h1 is greater than h2.

Alternatively, the cache could have a symmetrical shape about the N axis. In this way, the cache could be reversible.

Generally, the shape and height of the cover depends on the shape and height of the vein to be blocked.

This platform 31 has a rounded shape so as to form an extension of the portion 30 and to retain the oblong shape of the cover 3.

The platform 31 is configured to come and position itself opposite the first tapped orifice 40, and more precisely above the entrance of the first tapped orifice 40. In this way, the fact that the cover is fixed so as to close the vein 39 therefore leaves room for the head of the first fixing screw regardless of its positioning and tightening.

In order to be able to keep the cover 3 fixed against the upstream cone 1, fixing means are provided. Here, the cover 3 has a through hole 33 configured to be positioned opposite a second tapped orifice 50 formed in the vein 39, and capable of cooperating with a second fixing screw 5 so as to fix the cover 3 on the upstream cone 1.

In other words, the cover 3 is crossed by a through hole 33 configured to be positioned opposite a second tapped orifice 50 formed at the bottom of the vein 39, when the cover is in the position of closing the vein, a second fixing screw 5 being provided to be housed in this second tapped orifice 50 so as to fix the cover 3 on the upstream cone 1.

Preferably, the through hole 33 has one end having a fillet and the second fixing screw 5 is a tapped screw such that, once screwed into the through hole 33 and into the second tapped orifice 50, the head of the second fixing screw 5 is fully engaged in the through hole 33.

Here, the second tapped orifice 50 extends along an axis N normal to the direction of extension E of the vein 39.

In this way, and more particularly during the rotation of the turbomachine, the cover is kept fixed on the upstream cone. In addition, these fixing means are easily removable.

In this embodiment, and as more particularly visible in FIGS. 6 and 7, the second tapped orifice 50 of the second fixing screw 5 is centered on the first portion 30.

In this way, the through hole 33 and the second tapped orifice 50 form indexing means for the installation of the cover 3 so as to close the vein 39.

In this embodiment, and as visible in particular in figures 8a and 8b, the inlet cone here comprises at least three covers, each configured to be fixed on the upstream cone 1 so as to close a vein 39. As a result, three veins 39 are formed in this embodiment, each having a formed tapped orifice opening out so as to be able to house in each a first fixing screw 4 of the upstream cone to the downstream ferrule.

The three veins formed in the upstream cone are uniformly distributed around the periphery of the upstream cone. Here, two veins are separated by approximately 120° so that the three veins are uniformly distributed around the periphery of the upstream cone.

We now present, in relation to figures 5 to 7, the different stages of fixing the components of the inlet cone, in particular the upstream cone with the downstream ferrule, and the cover on the upstream cone.

As illustrated in , the first fixing step consists of inserting the first fixing screw 4 into the first tapped hole 40 and screwing it so that the head of the first fixing screw 4 is flush in the vein 39.

Previously, a step of aligning the upstream cone and the downstream ferrule is necessary so that the portion of the first tapped orifice 40 formed in the upstream cone 1 is aligned with the portion of the first tapped orifice 40 formed in the downstream ferrule 2.

Then, as illustrated in , the cover 3 is positioned opposite the vein so that the through hole 33 is positioned opposite the second tapped orifice 50 formed in the vein 39, then it is inserted into the vein 39 so as to close it.

Then, the user inserts the second fixing screw 5 into the second tapped hole 50 and then screws it so that the head of the second fixing screw 5 is fully inserted into the through hole 33.

Claims (10)

Inlet cone (9) for an aircraft turbomachine fan mounted to rotate about an axis of rotation (R), comprising an upstream cone (1) fixed by at least one first fixing screw (4) to a downstream shell (2), said first fixing screw (4) being configured to be housed in a first tapped orifice (40) formed partly in said upstream cone (1) and in said downstream shell (2), and opening into a vein (39) hollowed out on said upstream cone (1),
characterized in that the inlet cone (9) also comprises a cover (3) configured to be fixed on said upstream cone (1) so as to close said vein (39), the upstream cone (1), the downstream ferrule (2) and said cover (3) jointly forming a substantially continuous external surface of said inlet cone (9). Inlet cone (9) according to claim 1, characterized in that the cover (3) has a through hole (33) configured to be positioned opposite a second tapped orifice (50) formed in said vein (39), and capable of cooperating with a second fixing screw (5) so as to fix said cover (3) on said upstream cone (1). Inlet cone (9) according to one of claims 1 or 2, characterized in that said cover (3) has a shape complementary to said vein (39). Inlet cone (9) according to claim 2 or 3, characterized in that said cover (3) comprises a portion (30) having a substantially oblong shape, extended by a platform (31) having a second height (h2) less than the first height (h1), said platform (31) being configured to come and position itself opposite said first tapped orifice (40). Inlet cone (9) according to claim 4 dependent on claim 2, characterized in that the second tapped orifice (50) of the second fixing screw (5) is centered on the first portion (30). Inlet cone (9) according to one of claims 2 to 5, characterized in that the second tapped orifice (50) extends along an axis (N) normal to a direction of extension (E) of said vein (39). Inlet cone (9) according to one of the preceding claims, characterized in that it further comprises sealing means provided between the periphery of said cover (3) and the contour of said vein (39). Fan for an aircraft turbomachine mounted to rotate about an axis of rotation (R), characterized in that it comprises an inlet cone according to one of claims 1 to 7. Turbomachine for aircraft comprising a fan (9) according to claim 8. Turbomachine for aircraft according to claim 9, characterized in that it is a turbojet.