FR3126023A1 - Exhaust casing of a turbomachine - Google Patents

Abstract

The present invention relates to an exhaust casing (1) of a turbomachine comprising: - a hub (2) centered on an axis (XX') of the casing (1); - a ferrule (3) extending around the hub (2); - a plurality of arms (4) which extend from the hub (2) to the shroud (3), each arm (4) comprising an internal wall (41) defining a housing (40) extending between the hub (2 ) and the ferrule (3); and - at least one rib (5) fixed to the internal wall (41) of at least one arm (4), said rib (5) projecting from the internal wall (41) of the arm (4) between the hub (2) and the shroud (3), the at least one rib (5) extending as far as the hub (2) so as to form a thermal bridge. Figure for the abstract: Fig. 1

Description

Exhaust casing of a turbomachine

FIELD OF THE INVENTION

The invention generally relates to the field of turbomachines, and more particularly turbomachine exhaust casings.

STATE OF THE ART

A turbomachine has a main direction extending along a longitudinal axis and typically comprises, from upstream to downstream in the direction of gas flow, a fan, a low pressure compressor, a high pressure compressor, a combustion chamber, a high pressure turbine, and a low pressure turbine comprising in particular an exhaust casing. The exhaust casing contributes to delimiting the primary vein of the fluid (or primary flow of gases) crossing the turbomachine and ensures, via the bearing support, the concentricity between the rotor and the stator of the turbomachine, as well as the attachment of the downstream of the engine to the nacelle.

This exhaust casing conventionally comprises a hub, centered on the axis of the turbomachine, an outer shroud, coaxial with the hub, and a set of arms connecting the hub and the outer shroud.

The arms are in the primary flow and are therefore hotter than the outer shell and the hub. The arms of the exhaust casing are therefore subjected to significant thermal gradients which generate mechanical stresses in the arms having an impact on the life of the exhaust casing.

An exhaust casing is therefore subjected to a load of thermal origin but it is also subjected to a load of mechanical origin. The management of these two loads is however antagonistic: reducing the stresses of thermal origin generally requires reducing the flexibility of the casing while the reduction of the stresses of mechanical origin requires an increase in the thicknesses with for consequence an increase in the stiffness of the casing. .

An object of the invention is to remedy the aforementioned drawbacks, by proposing an exhaust casing whose service life is improved in comparison with the exhaust casings of the prior art, and in which the thermal gradients are reduced. In addition, the solution provided must not degrade the mechanical strength of the casing.

For this purpose, according to a first aspect of the invention, an exhaust casing of a turbomachine is proposed, the casing comprising:
- a hub centered on an axis of the housing;
- A ferrule extending around the hub;
- a plurality of arms which extend from the hub to the ferrule, each arm comprising an internal wall defining a housing extending between the hub and the ferrule; And
- at least one rib fixed to the internal wall of at least one arm, said rib projecting from the internal wall of the arm between the hub and the shroud, the at least one rib extending as far as the hub so as to form a thermal bridge.

Certain preferred but non-limiting characteristics of the exhaust casing according to the first aspect are the following, taken individually or in combination:
- the casing comprises at least two ribs, the wall of the arms comprising a first internal wall and a second internal wall, a first rib being fixed to the first internal wall and a second rib being fixed to the second internal wall;
- the housing comprises at least three ribs;
- each arm comprises at least one rib;
- the at least one rib extends beyond the hub in a direction radial to the axis;
- the at least one rib also extends as far as the ferrule, and may extend beyond the ferrule in a direction radial to the axis;
- a thermal conductivity of a material of the at least one rib is greater than a thermal conductivity of a material constituting the arms;
- the at least one rib is attached and fixed to the inner wall of an arm, for example by welding or brazing;
- the at least one rib is formed integrally and in one piece with the corresponding arm, for example by additive manufacturing; and or
- A section of the at least one rib is variable between the hub and the outer shroud.

According to a second aspect, the invention proposes a method for manufacturing an exhaust casing according to the first aspect comprising the following steps:
S2: make at least one rib in a material whose thermal conductivity is greater than the thermal conductivity of the material constituting the arm; And
S3: attach the at least one rib to the inner wall of an arm so that the at least one rib extends as far as the hub and, where applicable, as far as the ferrule.

The method may further comprise, prior to step S2, a step S1 of manufacturing two half-shells corresponding respectively to an intrados wall and an extrados wall of the arm, step S3 comprising fixing by brazing or welding of the at least one rib on the inner wall of the half-shells, the half-shells then being assembled to form the arm.

As a variant, steps S2 and S3 are carried out simultaneously by additive manufacturing.

According to a third aspect, the invention proposes a turbomachine, comprising an exhaust casing according to the first aspect and an aircraft comprising such a turbomachine.

DESCRIPTION OF FIGURES

Other characteristics, objects and advantages of the invention will emerge from the description which follows, which is purely illustrative and not limiting, and which must be read in conjunction with the appended drawings in which:

There shows an overview of an exhaust housing;

There illustrates an arm of an exhaust casing according to one embodiment of the invention;

There illustrates one half of an arm of an exhaust casing according to one embodiment of the invention; And

There is a flowchart of an exemplary method of manufacturing an exhaust casing arm according to one embodiment of the invention.

In all the figures, similar elements bear identical references.

Claims (12)

Casing (1) for the exhaust of a turbomachine comprising:
- a hub (2) centered on an axis (XX') of the housing (1);
- a ferrule (3) extending around the hub (2);
- a plurality of arms (4) which extend from the hub (2) to the shroud (3), each arm (4) comprising an internal wall (41) defining a housing (40) extending between the hub (2 ) and the ferrule (3); And
- at least one rib (5) fixed to the internal wall (41) of at least one arm (4), said rib (5) projecting from the internal wall (41) of the arm (4) between the hub (2) and the shroud (3), the at least one rib (5) extending as far as the hub (2) so as to form a thermal bridge. Exhaust casing (1) according to claim 1, comprising at least two ribs, preferably at least three ribs (5), the wall (41) of the arms (4) comprising a first internal wall (41a) and a second internal (41b), a first rib (5) being fixed on the first internal wall (41a) and a second rib (5) being fixed on the second internal wall (41b). Exhaust casing (1) according to one of Claims 1 and 2, in which the at least one rib (5) also extends as far as the ferrule (3). Exhaust casing (1) according to one of Claims 1 to 3, in which the at least one rib extends beyond the hub in a direction radial to the axis (XX'). Exhaust casing (1) according to one of Claims 1 to 4, in which a thermal conductivity of a material of the at least one rib (5) is greater than a thermal conductivity of a material constituting the arms ( 4). Exhaust casing (1) according to one of Claims 1 to 5, in which the at least one rib (5) is attached and fixed to the internal wall (41) of an arm (4), for example by welding or brazing. Exhaust casing (1) according to one of Claims 1 to 5, in which the at least one rib (5) is formed integrally and in one piece with the corresponding arm, for example by additive manufacturing. Exhaust casing (1) according to one of Claims 1 to 7, in which a section of the at least one rib (5) is variable between the hub (2) and the outer shroud (3). Method of manufacturing an exhaust casing (1) according to one of claims 1 to 8 comprising the following steps:
S2: make at least one rib (5); And
S3: fixing the at least one rib (5) on the internal wall (41) of an arm (4) so that the at least one rib (5) extends as far as the hub (2) and the if necessary up to the ferrule (3).
Manufacturing process according to claim 9, further comprising, prior to step S2, a step S1 of manufacturing two half-shells corresponding respectively to an intrados wall and an extrados wall of the arm (4), step S3 comprising the fixing by brazing or welding of the at least one rib (5) on the internal wall of the half-shells, the half-shells then being assembled to form the arm (4). Manufacturing process according to claim 9, in which steps S2 and S3 are carried out simultaneously by additive manufacturing. Turbomachine, comprising an exhaust casing (1) according to one of Claims 1 to 8.