FR3081924A1 - TURBOMACHINE FOR AN AIRCRAFT COMPRISING A PRESSURIZED FLUID CONDUIT SURROUNDED BY A BRAIDED OR WOVEN METAL SHEATH - Google Patents

Abstract

An aircraft turbomachine comprises at least one pressurized fluid conduit (50), and at least one braided or woven metal sheath (60) surrounding at least a portion of the conduit. In the event of a break, the metal sheath opposes the relative deformations and displacements of the parts (50A, 50B) of the duct situated on either side of the line or break zone, which makes it possible to limit the extent of the opening (54) formed within the duct due to the rupture, and therefore the flow rate of the pressurized fluid leak resulting from such a rupture.

Description

TURBOMACHINE FOR AN AIRCRAFT COMPRISING A PRESSURIZED FLUID CONDUIT SURROUNDED BY A BRAIDED OR WOVEN METAL SHEATH

DESCRIPTION

TECHNICAL AREA

The present invention relates to the field of turbomachines intended for the propulsion of aircraft, and relates more particularly to a turbomachine comprising a pressurized fluid conduit.

PRIOR STATE OF THE ART

An aircraft turbomachine generally comprises various conduits intended for the circulation of pressurized fluids.

Such ducts are in particular part of the air sampling system intended to supply air to the cabin of the aircraft and / or the system for defrosting the structure of the aircraft.

Such a system typically comprises several air sampling devices arranged at different locations of the turbomachine as well as valves for regulating the air flows circulating in the air sampling devices, and a heat exchanger. These different organs are interconnected by means of the system's conduits.

The document FR2976255A1 provides a more detailed description of an example of such a system.

In general, such conduits are subjected, in operation, to the pressure differential between the pressurized fluid which circulates there and their immediate environment.

This pressure differential is particularly marked in the case of conduits housed in non-pressurized spaces, for example in the space defined between the outer casing of the turbomachine and the outer wall of the nacelle arranged around the outer casing.

Such a pressure differential exposes the conduits to risks of rupture, in particular at the junctions between the different sections constituting each conduit, such a rupture being sometimes called "burst-duct".

In the event of a rupture of such a conduit, a large-scale leak of the pressurized fluid risks not only jeopardizing the operation of systems whose operation requires said fluid, but such a leak is also capable of causing a considerable increase in pressure in the environment of the conduit, and thereby damaging other elements located in this environment.

With regard to the conduits housed in the space defined between the outer casing of the turbomachine and the outer wall of the nacelle, taking into account the aforementioned risk leads to equipping the nacelle cowls with overpressure hatches.

STATEMENT OF THE INVENTION

The invention particularly aims to limit the consequences of a rupture of a pressurized fluid conduit of the type described above. In particular applications, the invention has the secondary objective of making superfluous the presence of overpressure doors within the nacelle cowls.

The invention proposes for this purpose an aircraft turbomachine, comprising at least one pressurized fluid conduit, and at least one braided or woven metal sheath surrounding at least a portion of the conduit.

In the event of rupture, the metal sheath opposes the relative deformations and displacements of the parts of the conduit situated on either side of the line or zone of rupture, which makes it possible to limit the extent of the opening formed within of the duct due to the rupture, and therefore the flow rate of the pressurized fluid leak resulting from such a rupture.

According to other advantageous aspects of the invention, the turbomachine has one or more of the following characteristics, taken in isolation or in any technically possible combination:

- the conduit extends beyond two opposite ends of the metal sheath;

- The conduit is formed of at least two sections connected to each other end-to-end, and the metal sheath surrounds a connection area of the two sections;

- the two sections are connected to each other by soldering or welding;

- the two ends of the metal sheath are fixed to the duct by soldering or welding;

- The metal sheath is made from metal cable having a diameter between 1 and 3 millimeters and braided or woven in a pitch between 5 and 15 millimeters;

- the diameter of the wire rope is equal to 2 millimeters and the pitch is equal to 10 millimeters;

- The duct extends in a space defined between an external casing of the turbomachine and an external wall of a nacelle of the turbomachine;

- the space extends around a secondary flow channel of the turbomachine;

- The duct is part of an air sampling system intended to be connected to the airframe of an aircraft.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be better understood, and other details, advantages and characteristics thereof will appear on reading the following description given by way of non-limiting example and with reference to the appended drawings in which:

- Figure 1 is a schematic view in axial section of a turbomachine;

- Figure 2 is an enlarged view of part of Figure 1;

- Figure 3 is a schematic side view of a pressurized fluid conduit of a known type turbomachine;

- Figure 4 is a view similar to Figure 3, illustrating the conduit after rupture thereof;

- Figure 5 is a schematic sectional view along the plane V-V of Figure 4, of the conduit after rupture thereof;

- Figure 6 is a view similar to Figure 3, illustrating a duct belonging to the turbomachine of Figure 1 and provided with a metal sheath according to the invention;

- Figure 7 is a view similar to Figure 6, illustrating the conduit after rupture thereof;

- Figure 8 is a schematic sectional view along the plane VIll-VIII of Figure 7, of the conduit after rupture thereof.

Throughout these figures, identical references may designate identical or analogous elements.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

FIG. 1 illustrates a turbomachine 10 for aircraft, generally comprising a fan 12 intended for the suction of an air flow dividing downstream of the fan into a primary flow circulating in a primary flow flow channel , hereinafter called the primary vein PF, within a core of the turbomachine, and a secondary flow bypassing this core in a secondary flow flow channel, hereinafter called the secondary vein SF.

The turbomachine is for example a turbofan engine with double flow and with a double body. The heart of the turbomachine thus generally comprises a low pressure compressor 14, a high pressure compressor 16, a combustion chamber 18, a high pressure turbine 20 and a low pressure turbine 22. The respective rotors of the high pressure compressor and of the high pressure turbine are connected by a shaft called "high pressure shaft", while the respective rotors of the low pressure compressor and of the low pressure turbine are connected by a shaft called "low pressure shaft", in a well known manner . The various rotors are rotatably mounted around a longitudinal axis 28 of the turbomachine.

Throughout this description, the axial direction X is the direction of the longitudinal axis 28. The radial direction R is at all points a direction orthogonal to the longitudinal axis 28 and passing through the latter, and the circumferential direction or tangential C is at any point a direction orthogonal to the radial direction R and to the longitudinal axis 28. The terms "internal" and "external" refer respectively to a relative proximity, and a relative distance, of an element relative to to axis 28. Finally, the “upstream” and “downstream” directions are defined by reference to the general direction of the flow of gases in the primary PF and secondary SF streams of the turbomachine, in the axial direction X.

The turbomachine is faired by a nacelle 24 surrounding the secondary stream SF. More specifically, the nacelle 24 typically comprises an external wall 24A extending over the entire length of the nacelle, and which is connected to internal walls upstream 24B and downstream 24C of the nacelle, respectively at the upstream and downstream ends of the nacelle, that is to say at the leading edge and the trailing edge. The upstream internal walls 24B and downstream 24C of the nacelle are connected respectively to the upstream and downstream ends of an external casing 26 of the turbomachine, which externally delimits part of the secondary stream SF. The external casing 26 comprises an upstream part commonly called “fan casing”, and a downstream part generally called “external casing of intermediate casing”.

As appears more clearly in FIG. 2, the external wall 24A of the nacelle and the external casing 26 define between them a space 30 which is not pressurized, that is to say subject to atmospheric pressure.

Within this space 30 is housed part of an air sampling system 40 intended to supply air to the cabin of an aircraft and / or the system for defrosting the structure of the aircraft, from pressurized air taken from various places in the turbomachine.

To this end, the system 40 includes several air sampling devices 42 arranged at different locations in the turbomachine, for example between the low pressure compressor 14 and the high pressure compressor 16 at the intermediate casing 44, at the outlet of the high compressor. pressure 16, and at the level of the secondary vein SF. The system 40 furthermore typically comprises valves 46 intended for regulating the air flows circulating in the air sampling devices 42, and a heat exchanger 48, commonly called “PCE” or “precooler” according to the terminology. Anglo-Saxon.

The air sampling system 40 finally comprises conduits 50 interconnecting the various elements 42, 46 and 48 mentioned above of the system.

These conduits 50 are subjected to high level stresses, due to the pressure differential existing between the pressure of the air circulating in the conduits and the pressure of the surrounding air, within the space 30, which in l The occurrence is substantially equal to atmospheric pressure. Such constraints expose the conduits 50 to risks of breakage.

The problem posed by turbomachines of known type is thus illustrated by FIGS. 3 to 5 which show a very schematic representation of a duct 50, respectively in normal operation (FIG. 3) and in a rupture situation (FIGS. 4 and 5). The conduit 50 is typically formed of several sections assembled end-to-end, for example two sections 50A and 50B connected to each other by brazing or welding at a connection zone 52. In this case, the risk of rupture is increased at the level of the connection zone (s) 52. As very schematically illustrated in FIGS. 4 and 5, such a rupture can cause the formation of an opening 54 of considerable magnitude, due to the deformations and relative displacements of the parts of the duct situated on either side of the rupture line, with the consequence of a significant leak of pressurized air. As explained above, such a leak is likely to affect the functioning of systems normally supplied by pressurized air coming from the duct in question, and to cause damage to elements close to the duct due to the overpressure caused in the surrounding environment. .

In order to limit these risks, the turbomachine according to the invention comprises one, or preferably several, braided or woven metal sheaths, each surrounding at least a portion of a duct 50.

In preferred embodiments of the invention, these metal sheaths do not cover all of the conduits 50 but are located around the portions of the conduits presenting increased risks of rupture, such as the connection zones between the different sections of each leads. In other words, each of these conduits 50 extends beyond the ends of the corresponding metal sheath (s).

Figures 6 to 8, which correspond respectively to Figures 3 to 5, show one of the conduits 50 fitted with such a metal sheath 60 surrounding the connection zone of the sections 50A, 50B.

As shown in Figure 6, the ends 62A, 62B of the metal sheath 60 are respectively fixed on the sections 50A, 50B of the conduit, preferably by a solder or by a weld.

In the event of a break, as illustrated in FIGS. 7 and 8, the metal sheath 60 allows, due to its resistance, to limit the deformations and relative displacements of the sections 50A, 50B of the conduit 50, and thus to limit the extent of the opening 54 of the conduit resulting from the rupture.

The extent of the pressurized air leak can thus be kept less than or equal to a level considered acceptable, by means of an appropriate dimensioning of the metal sheath 60.

In this regard, the metal sheath is preferably made from metal cable having a diameter between 1 and 3 millimeters and braided or woven in a pitch between 5 and 15 millimeters. This last dimension concerns the spacing between two successive parallel strands 56A, 56B of the sheath (FIG. 6).

In a preferred embodiment of the invention, the diameter of the metallic cable is equal to 2 millimeters and the pitch is equal to 10 millimeters. These dimensions have indeed proved to be optimal in the context described above.

Of course, zones other than the zones for connecting sections of the conduits can, as a variant or in a complementary manner, be covered with metal sheaths according to the principle described above. They may in particular be bent regions, which also present an increased risk of rupture.

In its application, described above, to an air sampling system comprising ducts housed in the aforementioned space, the invention has the additional advantage of making the presence of overpressure doors superfluous within the wall. external 24A of the nacelle.

Furthermore, the invention is applicable to other types of ducts, intended for the circulation of pressurized air or any other pressurized fluid, housed in any type of space within a turbomachine.

Finally, the invention is of course applicable to other types of turbomachinery, for example single-body and / or single-flow turbomachinery, or else turbopropellers.

Claims (10)

1. Turbomachine for aircraft, comprising at least one pressurized fluid conduit (50), characterized in that it comprises at least one braided or woven metal sheath (60) surrounding at least a portion of the conduit (50). 2. A turbomachine according to claim 1, in which the duct (50) extends beyond two opposite ends (62A, 62B) of the metal sheath (60). 3. Turbomachine according to claim 2, in which the duct (50) is formed of at least two sections (50A, 50B) connected to each other end-to-end, and the metal sheath (60) surrounds an area connecting (52) of the two sections. 4. A turbomachine according to claim 3, in which the two sections (50A, 50B) are connected to one another by brazing or welding. 5. A turbomachine according to any one of claims 2 to 4, in which the two ends (60A, 60B) of the metal sheath (60) are fixed to the duct (50) by brazing or welding. 6. Turbomachine according to any one of claims 1 to 5, in which the metal sheath (60) is produced from metal cable having a diameter between 1 and 3 millimeters and braided or woven in a pitch between 5 and 15 millimeters. 7. The turbomachine according to claim 6, in which the diameter of the metal cable is equal to 2 millimeters and the pitch is equal to 10 millimeters. 8. Turbomachine according to any one of claims 1 to 7, in which the duct (50) extends in a space (30) defined between an external casing (26) of the turbomachine and an external wall (24A) of a nacelle (24) of the turbomachine. 9. A turbomachine according to claim 8, in which the space (30) extends around a secondary flow channel (SF) of the turbomachine. 10. Turbomachine according to any one of claims 1 to 9, in which the duct (50) is part of an air sampling system (40) intended to be connected to the airframe of an aircraft.