Centrifugal deaerator for a turbomachine

Abstract

The invention relates to a centrifugal deaerator for an air/oil mixture of a turbomachine, comprising: an annular housing (10) for the centrifugal separation of said mixture, arranged around a hollow shaft (11); axial inlets (14) for the flow of said air/oil mixture into said housing (10); a pinion (20) for rotating said housing (10); and radial oil outlets (15) and oil-free air outlets (16), characterised in that it comprises a metal foam (50) housed in said housing (10) by partially extending along the axial direction (XX′) so as to define two successive spaces, a foam-free space (51) and a foam-lined space (52), said foam-free space opening up towards said axial inlets. A device can be advantageously added to the hollow shaft in order to reduce the free-vortex phenomenon and to thereby significantly reduce the load losses of the deaerator.

Claims

1. A centrifugal deaerator for an air/oil mixture of a turbomachine comprising: an annular housing for centrifugal separation of said mixture arranged around a hollow shaft extending along an axial direction, and delimited by an outer annular wall and an inner annular wall, at least one axial inlet of said air/oil mixture in said housing, a pinion for rotating said housing comprising a web securely connected to said inner and outer annular walls such that a rotation of said pinion drives said housing in rotation, at least one radial oil outlet arranged in said outer annular wall and configured to evacuate the oil separated from said mixture towards an outside of the deaerator, at least one de-oiled air outlet arranged in said inner annular wall and configured to evacuate the de-oiled air towards said hollow shaft, a metal foam housed in said housing by extending partially along said axial direction so as to delimit two successive spaces along the axial direction, a foam-free space and a foam-lined space, said foam-free space opening onto said at least one axial inlet.

2. The deaerator according to claim 1, wherein said metal foam presents a variable thickness between the inner annular wall and the outer annular wall of the housing to standardise load losses between zones close to the inner annular wall little subjected to the centrifugal force and zones close to the outer annular wall highly subjected to the centrifugal force.

3. The deaerator according to claim 1, wherein each said de-oiled air outlet is free of metal foam.

4. The deaerator according to claim 1, wherein said housing is formed of a plurality of compartments arranged radially around the hollow shaft, each said compartment being provided with mixture through one of said at least one axial inlets connected to one of said at least one radial oil outlets and to one of said de-oiled air outlets, each compartment comprising two successive spaces along the axial direction, a foam-free space and a foam-lined space, said foam-free space opening onto said at least one axial inlet.

5. The deaerator according to claim 1, wherein a vortex inhibitor is housed in said hollow shaft.

6. The deaerator according to claim 5, wherein the vortex inhibitor comprises flow recovery blades.

7. A turboshaft comprising a mechanical member of the accessory box or reduction gear type, wherein said turboshaft comprises the deaerator according to claim 1, adapted to be driven in rotation by said mechanical member.

Description

5. LIST OF FIGURES

(1) Other aims, features and advantages of the invention will appear upon reading the following description given only in a non-limiting manner and which refers to the appended figures, wherein:

(2) FIG. 1 is a schematic, perspective and cross-sectional view along a symmetrical plane of a deaerator according to an embodiment of the invention,

(3) FIG. 2 is a partial, schematic, perspective and cross-sectional view along a symmetrical plane of the deaerator of FIG. 1 highlighting the functioning principle of this deaerator, and

(4) FIG. 3 is a schematic, perspective and cross-sectional view along a symmetrical plane of a deaerator according to an embodiment variant of the invention.

6. DETAILED DESCRIPTION OF AN EMBODIMENT OF THE INVENTION

(5) In the figures, the scales and proportions are not strictly adhered to and this, for purposes of illustration and clarity.

(6) A deaerator according to the invention comprises, such as represented in FIG. 1, an annular housing 10 for the centrifugal separation of an air/oil mixture arranged around a hollow shaft 11. This annular housing 10 is delimited by an outer annular wall 12 and an inner annular wall 13. This housing 10 comprises a plurality of deaerating compartments distributed around the hollow shaft 11.

(7) The deaerator further comprises a plurality of axial inlets 14 allowing the air/oil mixture to enter into the housing 10. Each compartment of the housing 10 is connected to an axial inlet 14 such that each compartment can receive a mixture to be separated by a dedicated inlet.

(8) The deaerator further comprises a plurality of radial oil outlets 15 arranged in the outer wall 12 and configured to be able to evacuate the oil separated from the mixture by the effect of the centrifugal force of the deaerator. Each compartment of the housing 10 is connected to one or more radial oil outlet(s) 15.

(9) The deaerator further comprises a plurality of de-oiled air outlets 16 arranged in the inner wall 13 and configured to be able to evacuate the de-oiled air towards the hollow shaft 11. Each compartment of the housing 10 is connected to at least one de-oiled air outlet 16.

(10) Finally, the deaerator comprises a pinion 20 for rotating the housing 10 comprising a web 21 securely connected to the hollow shaft 11 and to the inner 13 and outer 12 annular walls.

(11) A deaerator according to the invention further comprises metal foams 50 arranged in each compartment of the housing 10. These foams are, for example, foams commercialised under the brand Retimet®. They allow improving the effectiveness of the deaerator by increasing the probability of capturing oil particles.

(12) According to the invention, the metal foams 50 do not fully extend in the compartments, but only extend over an axial portion of each compartment so as to form two separate successive spaces in the compartment: a foam-free space 51 and a foam-lined space 52. The foam-free space 51 is provided with mixture through the axial inlets 14 and it opens into the foam-lined space 52. The foam-lined space 52 opens into the peripheral oil outlets. The foam-free space 51 thus presents a simple centrifugal function of the deaerator allowing the oil/air mixture to enter into the housing 10 of the deaerator, then to axially move in a rotating marker. During this movement, a first de-oiling phase is carried out. The foam-lined space 52 presents a function for capturing oil drops not extracted during the first phase. This second de-oiling phase is furthermore carried out in the foam-lined space 52 without notable load losses due to the axial attack of the oil drops. In addition, the separation of the housing between a foam-free space and a foam-lined space allows avoiding the saturation of metal foams of the foam-lined space by a first de-oiling phase in the foam-free space. The inventors have realised that this architecture allows providing results which combine low load losses of the deaerators, totally foam-free, and the good separation of deaerators, totally foam-lined. In other words, the two spaces cooperate to provide a result which goes beyond the sum of the results of each of the two spaces taken individually.

(13) According to an advantageous embodiment represented in FIG. 2, the metal foams present, in each compartment, a variable thickness between the inner wall 13 and the outer wall 12, which allows standardising the load losses between the zones close to the inner wall 13 which are not highly subjected to the centrifugal force and the zones close to the outer wall 12 highly subjected to the centrifugal force.

(14) FIG. 2 also schematically illustrates the movement of oil drops 55 in a metal foam. The oil drops 55 are captured by the foam 50 and move towards the periphery of the deaerator due to the centrifugal force resulting from the rotating of the housing by way of the pinion 20. However, the de-oiled air is naturally evacuated towards the hollow shaft 11 of the deaerator.

(15) The deaerator according to the embodiment of the figures further comprises axial mixture inlets 14 and radial oil outlets 16 arranged axially on either side of the web 21 of the pinion 20.

(16) This specific arrangement of the inlet 14 and of the outlets 16 with respect to the web 21 of the pinion 20 allows preventing any reintroduction in the housing of oil evacuated through the radial outlets. In particular, the oil evacuated through the outlets 15, formed by orifices in the outer wall 12, cannot be directed towards the inlets 14 because the pinion 20 acts as a separation wall. Furthermore, the rotation of the pinion generates an air wall which prevents the oil circulation towards the inlets 14. Indeed, the teeth of the pinion 20 mix air during the rotation of the pinion, which has the effect of forming an air wall which prevents the oil passage towards the axial inlets 14.

(17) FIG. 3 schematically illustrates the airflow reoriented by a vortex inhibitor 60 housed in the hollow shaft 11, in order to avoid a rotating of the airflow or vortex which would generate substantial load losses, in particular in high-speed, rotating applications. This inhibitor 60 comprises, for example, a generally cone-shaped body 62 of which the tip is oriented downstream and centred on the axis XX′ of the deaerator. Blades 64 extend radially towards the outside from this cone and force the airflow entering into the hollow shaft to flow substantially parallel to the axis XX′. The blades are regularly distributed about the axis XX′ and each extend in a substantially radial plane passing through the axis XX′.

(18) Furthermore, according to an advantageous embodiment not represented in the figures, the deaerator comprises an anti-return disc which extends perpendicularly to the outer wall and which partially blocks the axial inlets so as to prevent an oil outlet in the vicinity of the outer wall through the axial inlets. Thus, the oil in the vicinity of the outer wall cannot emerge from the housing through the inlets, because it is blocked by the disc which extends in the vicinity of the outer wall. This disc is, for example, produced by an excrescence of the web of the pinion at the level of the inlets.

(19) The invention is not limited only to the embodiments described in line with the figures. For example, according to other embodiments not represented, the metal foams can have other geometries inside compartments of the housing without questioning the principle of the invention, which is to provide metal foams inside the housing which extend only partially inside the housing along the axial direction.