Discharge duct of an intermediate housing hub for an aircraft turbojet engine comprising cooling channels

Abstract

A discharge duct (30) of an intermediate housing hub for an aircraft turbojet engine, comprises an inlet end (41) and an outlet end (42), intended to ensure the passage of air from at least one discharge inlet opening to at least one secondary outlet opening, and comprising an ejection grill (32) arranged at the outlet end (42), the ejection grill (32) comprising a plurality of fins (43), characterised in that the fins (43) comprise flow channels (44) for a fluid to be cooled, so as to form a heat exchange system.

Claims

1. A hub of an intermediate housing for an aircraft turbojet engine, including a discharge duct having an inlet end and an outlet end and defining an air passage from at least one inlet end orifice to at least one outlet end orifice with an air flow in the discharge duct flowing in an air flow direction toward said at least one outlet end orifice, and including an ejection grille disposed at a level of the outlet end, said ejection grille including a plurality of fins, wherein inside at least one of the plurality of fins is a plurality of circulation channels for circulating a fluid to be cooled so as to form a heat exchange system, the plurality of circulation channels being transverse to the air flow direction, said at least one of the plurality of fins extending across the discharge duct from a first shank at a first wall of the discharge duct to a second shank at a second wall of the discharge duct, the first shank configured to attach to one distal end of said at least one of the plurality of fins and the second shank configured to attach to an opposite distal end of said at least one of the plurality of fins, the first shank including a first manifold section inside the first shank and the second shank including a second manifold section inside the second shank, the plurality of circulation channels extending from the one distal end to the opposite distal end, wherein at the one distal end the plurality of circulation channels each open into the first manifold section and at the opposite distal end the plurality of the circulation channels each open into the second manifold section, the hub further including: an inner annular ferrule delimiting externally a primary flow space of a primary gas flow in the turbojet engine and delimiting internally at least one inter-jet zone, the inner annular ferrule being provided with at least one primary air passage orifice, an outer annular ferrule delimiting externally a secondary flow space of a secondary gas flow in the turbojet engine and delimiting internally said at least one inter-jet zone, the outer annular ferrule being provided with said at least one outlet end orifice, and a downstream cross flange, connecting the inner and outer annular ferrules and delimiting upstream at least one intermediate space and delimiting downstream said at least one inter-jet zone, the downstream cross flange comprising said at least one inlet end orifice.

2. The hub of the intermediate housing according to claim 1, wherein the plurality of circulation channels extends inside said at least one of the plurality of fins parallel with one another.

3. The hub of the intermediate housing according to claim 1, wherein the plurality of circulation channels has a circular shaped cross-section.

4. The hub of the intermediate housing according to claim 1, wherein the plurality of circulation channels has a star shaped cross-section.

5. The hub of the intermediate housing according to claim 1, wherein the plurality of fins is formed by an additive manufacturing method.

6. The hub of the intermediate housing according to claim 1, further includes: at least one discharge valve comprising at least one movable gate suitable for extracting through said at least one primary air passage orifice air circulating in the primary flow space and for directing said air to said at least one intermediate space, wherein said air is directed towards the discharge duct, the discharge duct situated in said at least one inter-jet zone and formed to provide the air passage from said at least one inlet end orifice to said at least one outlet end orifice to direct the air extracted via said at least one discharge valve in the air flow direction and into the secondary flow space.

7. An intermediate housing for an aircraft turbojet engine, including the hub according to claim 1.

8. An aircraft turbojet engine, including the intermediate housing according to claim 7.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The invention may be understood more clearly on reading the following detailed description, of non-limiting examples of embodiments thereof, as well as examining the schematic and partial figures of the appended drawing, wherein:

(2) FIG. 1 represents, in an axial cross-section, an example of an intermediate housing hub for an aircraft turbojet engine,

(3) FIG. 2 illustrates, in a partial schematic axial cross-section, a principle of fastening a discharge duct to the outer ferrule of an intermediate housing hub for an aircraft turbojet engine, i.e. the creation of the interface between the discharge duct and the outer ferrule of the hub, comprising an ejection grille,

(4) FIG. 3 illustrates, according to a partial perspective and cross-sectional view, an example of a discharge duct of an intermediate housing hub for an aircraft turbojet engine according to the invention, including an ejection grille with fins provided with channels for circulating a fluid to be cooled,

(5) FIG. 4 illustrates, according to an enlarged partial perspective view, an embodiment detail of the circulation channels in FIG. 3,

(6) FIG. 5 illustrates, according to a partial perspective view, an alternative embodiment of the circulation channels in FIG. 3, and

(7) FIG. 6 illustrates, in a partial schematic radial cross-section, the grille in FIG. 2 for the connection thereof to an oil circuit.

(8) In all of these figures, identical references can designate identical or equivalent elements.

(9) Furthermore, the different parts represented in the figures are not necessarily represented according to a uniform scale, in order to render the figures more readable.

Detailed Description of Particular Embodiments

(10) Throughout the description, it is noted that the terms upstream and downstream are to be considered in relation to a main normal gas flow direction F (from upstream to downstream) for a turbojet engine 12. Moreover, axis T of the turbojet engine 12 refers to the axis of radial symmetry of the turbojet engine 12. The axial direction of the turbojet engine 12 corresponds to the axis of rotation of the turbojet engine 12, which is the direction of the axis T of the turbojet engine 12. A radial direction of the turbojet engine 12 is a direction perpendicular to the axis T of the turbojet engine 12. Moreover, unless specified otherwise, the adjectives and adverbs axial, radial, axially and radially are used with reference to the axial and radial directions cited above. Furthermore, unless specified otherwise, the terms internal (or inner) and external (or outer) are used with reference to a radial direction such that the internal portion of an element is closer to the axis T of the turbojet engine 12 than the external portion of the same element.

(11) FIGS. 1 and 2 help illustrate the technical context of the invention as also described for example in French patent application FR 3 036 136 A1 filed by the Applicant.

(12) Thus, FIG. 1 represents partially, in an axial cross-section, an example of a hub 10 of an intermediate housing 11 for a twin-spool and dual-flow aircraft turbojet engine 12 of a known type.

(13) The hub 10 of the intermediate housing 11 usually includes two coaxial annular, respectively inner 13 and outer 14, ferrules mutually connected by two cross flanges, namely an upstream cross flange 15 and a downstream cross flange 16.

(14) The upstream cross flange 15 is arranged downstream from a low-pressure compressor 17 of the turbojet engine 12, whereas the downstream cross flange 16 is arranged upstream from a high-pressure compressor 18 of this turbojet engine 12. This high-pressure compressor 18 generally comprises a succession of rotors and stators with variable timing, suitable for controlling the air flow rate traversing therethrough.

(15) Moreover, between the inner 13 and outer ferrules 14, and between the upstream 15 and downstream cross flanges 16, intermediate spaces 19 are provided distributed about the axis of the hub 10, merged with the axis of rotation T of the turbojet engine 12. The intermediate spaces 19 are upstream from an inter-jet zone ZC.

(16) Furthermore, the inner ferrule 13 delimits an annular primary flow space 20 of a primary flow of the turbojet engine 12. Moreover, the inner ferrule 13 includes air passage orifices 21, referred to hereinafter as primary orifices, each whereof is closed by the pivoting flap 22 of a corresponding discharge valve 23, intended for regulating the flow rate of the high-pressure compressor 18, and if applicable, for evacuating air, water or debris as explained above.

(17) Such a discharge valve 23 usually takes the form of a gate 24, which includes the pivoting flap 22 at the radially inner end thereof and which is pivotably mounted about an axis Y such that, in the closing position of the primary orifices 21, the flap 22 extends the inner ferrule 13 of the intermediate housing 11 substantially continuously to optimally reduce the risks of aerodynamic disturbances of the primary flow by this flap 22, and that in the opening position of said primary orifices 21, the flap 22 projects radially inwards in relation to the inner ferrule 13 and thus forms a scoop for extracting a portion of the primary flow into the space 20. The gate 24 includes a pipe 25 whereby the scoop air transits, this pipe 25 ending downstream on an outlet orifice 26 opening into the corresponding intermediate space 19. French patent application FR 2 961 251 A1 filed by the Applicant also describes a further example of a discharge valve of an intermediate housing hub for an aircraft turbojet engine.

(18) Moreover, the outer ferrule 14 delimits an annular secondary flow space 27 of a secondary flow F2 of the turbojet engine 12, and is connected to structural arms 28, relatively spaced apart from one another, traversing this space 27. Furthermore, the outer ferrule 14 includes air passage orifices 29, referred to hereinafter as secondary orifices, and arranged downstream from the downstream cross flange 16. In other words, in this example in FIG. 1, the air, water or debris is evacuated via the external ferrule 14.

(19) However, in an alternative embodiment (not shown), when for example the outer ferrule 14 bears guide valves that are relatively close to one another, the latter impeding the above-mentioned evacuation through the outer ferrule 14. In this case, it may be desirable to enable this evacuation further downstream, via the annular wall of an extension of the hub of the intermediate housing, i.e. the annular wall of a structural part which is sometimes used to support at the downstream end thereof thrust reverser elements such as fairing panels.

(20) When the variable-timing stators of the high-pressure compressor 18 are in a position reducing the air flow rate entering this compressor, excess air in the secondary flow space can then be evacuated via the secondary orifices 29, thus preventing pumping phenomena liable to result in damage, or even complete destruction, of the low-pressure compressor 17.

(21) Moreover, as explained above, discharge ducts 30 each extend between a respective inlet orifice 31 opening into the intermediate space 19 and a corresponding secondary outlet orifice 29. The inlet orifice 31 is provided at an inlet end 41 of the duct 30 at the connection thereof with the downstream cross flange 16. Inside these discharge ducts 30 a discharge flow FD, from the primary flow, circulates towards the secondary flow F2. The inlet orifice 31 is generally arranged level with the surface of the downstream cross flange 16 overlooking the intermediate space 19. The secondary outlet orifice 29 includes for its part a control grille 32, fastened to the discharge duct 30 at the outlet thereof, to be able to control the discharge flow FD during the discharge thereof into the secondary flow F2. The secondary orifice 29 is provided at an outlet end 42 (FIG. 3) of the duct 30 at the connection thereof with the outer ferrule 14.

(22) In each intermediate space 19, the outlet orifice 26 of the pipe 25 and the inlet orifice 31 of the discharge duct 30 are arranged facing one another.

(23) Each gate 24, and the corresponding downstream intermediate space 19 and discharge duct 30 thus form together a system for evacuating air, water or debris, referred to generally using the expression “discharge valve”, from the primary flow space 20 to the secondary flow space 27. The hub 11 therefore includes a plurality of such systems distributed about the axis T thereof.

(24) When a gate 24 is in the open position, an air flow scooped thereby traverses the primary duct 25, opens into the intermediate space 19 via the outlet orifice 26 thereof, enters the corresponding discharge duct 30 until it reaches the secondary flow space 27.

(25) Moreover, FIG. 2 represents, in a partial schematic axial cross-section, a principle of fastening of a discharge duct 30 to the outer ferrule 10 of an intermediate housing 11 of an aircraft turbojet engine 12, in other words the embodiment of the interface between the discharge duct 30 and the outer ferrule 14 of the hub 10.

(26) Thus, the discharge duct 30 is fastened to the outer annular ferrule 14 at the level of the secondary outlet orifice 29 an airtight and fireproof seal 33, made for example of silicone, is arranged between the discharge duct 30 and the outer annular ferrule 14. More specifically, the outer ferrule 14 includes an annular boss 37 and the discharge duct 30 includes an annular dimpling 36. The fastening of the discharge duct 30 to the outer ferrule 14 is then carried out by means of screwing means 34 passing through the annular boss 37 and the annular dimpling 36. Furthermore, the assembly formed by the annular boss 37 and the annular dimpling 36 extends all around the seal 33, forming a separation between the seal 33 and the inter-jet zone ZC.

(27) Moreover, an ejection grille 32, or control grille, is disposed at the level of the secondary outlet orifice 29. This ejection grille 32 includes a plurality of fins 43 for guiding the fluid from the low-pressure compressor to the secondary flow. The seal 33 is then disposed all around the ejection grille 32, which is fastened to the discharge duct 30 by screwing means 35. Thus, the seal 33 is situated between the ejection grille 32 and the assembly formed by the annular boss 37 and the annular dimpling 36.

(28) Advantageously, the solution according to the invention, seen in FIGS. 3 to 5, uses the fins 43 of the ejection grille 32 to form a heat exchanger suitable for cooling a given fluid.

(29) Thus, FIG. 3 illustrates, according to a partial perspective view, an example of a discharge duct 30 according to the invention, including an ejection grille 32 with fins 43 provided with circulation channels 44 of a fluid to be cooled. FIG. 4 illustrates, according to an enlarged partial perspective view, an embodiment detail of the circulation channels 44 in FIG. 3, and FIG. 5 illustrates, according to a partial perspective view, an alternative embodiment of the circulation channels 44 in FIG. 3.

(30) Advantageously, the fins 43 are modified, for example by drilling or by additive manufacture, so as to obtain multiple circulation channels 44 of a fluid to be cooled and to form a heat exchange system. The heat exchange is then carried out by means of the volume of the fins 43 capable of being modified to offer the largest possible heat exchange surface area.

(31) With reference to FIGS. 3 and 4, the circulation channels 44 of the fins 43 can have, as a cross-section, a circular shape and can also extend inside the fins 43 substantially parallel with one another, as seen in FIG. 4.

(32) In FIG. 5, the circulation channels 44 have, as a cross-section, a star shape. Indeed, this solution can be envisaged in order to maximise the heat exchange surface areas.

(33) It should be noted that the hub 10 of an intermediate housing 11 according to the invention, associated with the discharge duct 30 in FIGS. 3 to 5 described above, can particularly be of the same type as that described with reference to FIGS. 1 and 2. Also, for the parts not shown in FIGS. 3 to 5, it is advised to refer to the previous description of FIGS. 1 and 2.

(34) Moreover, the circulation channels 44 are connected to an oil circuit of the type of that existing for usually supplying exchangers. FIG. 6 is a schematic, cross-sectional view taken radially to the axis of rotation of the engine through one of the fins 43 showing one of the channels 44 thereof. The lateral periphery of the grille is press-fitted to the longitudinal edges of the discharge duct 30, via lateral shanks 320. The ends of the fins 32 have the circulation channels 44 thereof tightly leading by means of known type to lines 324 provided in the shanks 320 of the grille 32. These lines 324 have at the ends thereof on the fin side, at each lateral edge of the grille, a manifold section 324A wherein the channels 44 open. At the other end, the lines 324 are connected via seals by means of known type to tubes 326 connected to the engine oil circuit, which does not need to be described.

(35) Obviously, the invention is not limited to the examples of embodiments described above. Various modifications can be made by those skilled in the art.