FR3108932A1 - VENTILATION DEVICE FOR A TURBOMACHINE STATOR CASE - Google Patents

Abstract

The present invention relates to a ventilation device (17) for a stator casing (11) of a turbine engine (1), comprising:- at least one passage duct (20) for an air flow (F2) whose a first portion (21) forms an air inlet and a second portion (22) forms an air outlet, - at least one air distribution box (24) into which the second portion (22) opens and comprising a plurality of ramps (25) intended to extend around the casing, - the second portion is connected by connecting members (30) to the housing, the members (30) being configured to allow axial movement of the second portion ( 22) vis-à-vis the housing (24) along a first axis (X) of the duct (20) and/or an angular movement of the second portion vis-à-vis the housing around the first axis, of a second (Y) and a third (Z) axes perpendicular to the first axis (X). Figure for abstract: Figure 2

Description

VENTILATION DEVICE FOR A TURBOMACHINE STATOR CASE

Technical field of the invention

The present invention relates to a ventilation device for a stator casing of a turbine engine, in particular an aircraft.

Technical background

The value of the radial clearances between a rotor and a stator of a turbomachine, and in particular between blades of the rotor and a casing of the stator extending around these blades, for example the casing of a low pressure turbine, is of fundamental importance. on the performance of the turbomachine. In a known manner, this type of clearance is preferably controlled by using a crankcase ventilation device with air taken from a cold air flow, such as the secondary flow in a dual-flow turbomachine. The flow rate of the air taken in is regulated to control the cooling of the casing, in order to control its expansion and therefore the clearances with the rotor blades.

The low pressure turbine crankcase ventilation device is better known as LPTACC or “low pressure turbine active control clearance” (“Low pressure turbine clearance active control system” in French).

Traditionally, the ventilation device comprises at least one intake scoop in the air flow allowing the supply of a circuit, the latter distributing and projecting the air intake on the external face of the casing.

For example, it is known from document FR-A1-3 002 972 to install a control valve in the circuit to regulate the flow of air drawn off and thus control the cooling of the housing. According to this configuration, the air supplying the circuit is captured via a passive sampling scoop, located in the flow path of the secondary flow. The device generally comprises at least one air flow conduit, a first portion forming an air inlet and a second portion forming an air outlet. This second portion is configured to open into at least one air distribution box. This distribution box is connected to annular ducts, called "ramps", which are perforated to project the air flow towards the casing of the stator of the turbomachine. The second portion of the duct and the casing are bonded to each other generally by welding.

However, in operation, the welding connection may be subject to alternating tensile and compressive stresses liable to create and propagate cracks on this connection. This can cause a partial or total rupture of the connection between the air flow passage duct and the air distribution box, and consequently a leak from the ventilation device. A leak in the device does not make it possible to effectively cool the casing of the turbomachine.

In operation, the fact of no longer controlling the temperature of the casing implies that the predefined requirements of the radial clearances between the rotor and the stator are not respected. Leakage from the ventilation device can thus lead not only to a deterioration in the performance of the turbomachine but also to premature wear of the ventilation device.

In this context, it is interesting to overcome the drawbacks of the prior art, by proposing a reliable ventilation device with an improved lifetime for a stator casing of a turbomachine.

The present invention proposes a simple, effective and economical solution to at least some of the aforementioned problems.

The invention proposes for this purpose a ventilation device for an annular stator casing of a turbomachine, in particular of an aircraft, comprising:
- at least one conduit for passing an air flow, a first portion of which forms an air inlet and a second portion forms an air outlet, and
- At least one air distribution box into which the second portion of the duct opens and comprising a plurality of annular ramps intended to extend around the casing and configured to project the flow of air onto the casing.

According to the invention, the second portion of the duct is connected by connecting members to the housing, the connecting members being configured to allow axial movement of the second portion of the duct with respect to the housing along a first longitudinal axis of the duct and/or at least one angular movement of the second portion of the duct with respect to the housing around the first, a second and a third longitudinal axes, the second and third axes each being perpendicular to the first axis.

Such a configuration of the ventilation device makes it possible to prevent localized wear and cracking of the connection between the air flow passage duct and the air distribution box. For this, the device incorporates connecting members between the second portion of the passage duct and the housing. These connecting members make it possible to mechanically connect the second portion of the duct and the casing, while providing mobility and flexibility between these two elements. In this way, the connection adapts to follow the displacement(s) to which the second portion of the duct or the casing are subjected, in particular during the operation of the turbomachine.

In the present application, a pivot or slide connection is understood to mean a connection having a degree of freedom, respectively in rotation or in translation along its longitudinal axis (that is to say the first axis), and the other degrees of freedom being blocked (two in rotation and three in translation for the pivot connection, or vice versa in the case of the sliding connection). A sliding pivot connection is a pivot connection where the degree of freedom in translation along the axis of rotation of the pivot is released. Thus a sliding pivot connection (or cylinder-cylinder contact) allows movements according to one degree of freedom in rotation and according to one degree of freedom in translation, while the other four degrees of freedom (two in translation and two in rotation) are blocked . A ball joint is a joint with three degrees of rotational freedom. Finally, an annular linear connection (or sphere-cylinder contact) allows movements according to the three degrees of freedom in rotation and according to one degree of freedom in translation, while the other two degrees of freedom in translation are blocked.

It is therefore understood that the connecting members according to the invention can be one or a combination of at least two of the following connections:
- a slide-type connection which is in translation along the first axis,
- a pivot type connection which rotates around the first axis,
- a sliding pivot type connection which is in translation along the first axis and both in rotation around the first axis,
- a ball joint type connection which is in rotation around at least one of the first, second and third axes, and
- an annular linear type connection which combines the movements produced by the sliding pivot and ball joint connections.

Furthermore, these aforementioned connections being slippery, a movement of the second portion of the air passage duct relative to the air distribution box induces no, or very little, force in the connecting members and in the elements (the second portion of the duct or the box) which are connected to it.

The invention therefore has the advantage of proposing a simple design, offering very high reliability, and not very penalizing in terms of cost and size of the ventilation device in the turbomachine.

The ventilation device according to the invention may comprise one or more of the following characteristics, taken separately from each other or in combination with each other:
- the connecting members comprise a connecting piece to the second portion of the duct, the connecting piece passing through an orifice of the housing and comprising a threaded portion receiving a nut housed in the housing and an annular sealing device being mounted around the threaded portion and inserted between the nut and a peripheral edge of the orifice,
- that said connecting members are of the ball-and-socket type,
- the connecting members comprise a ball joint carried by the nut, in which at least part of the ball joint is housed in the orifice of the housing,
- the second portion of the duct and the connecting piece are interconnected by a sliding pivot connection,
- the connecting members further comprise a clamp arranged around the connecting piece and configured to hold the second portion of the duct connected to the connecting piece in position,
- the nut comprises a base arranged inside the casing with an external diameter greater than an internal diameter of the orifice of the casing,
- the nut further comprises a collar with an external diameter smaller than the internal diameter of the housing of the housing,
- the sealing device is an O-ring adapted to be compressed between the nut and the peripheral edge of the orifice when the second portion of the duct moves axially along the first axis, and/or to adopt the angular movement of the second portion around the second and/or third axes,
- the annular sealing device is made of an elastically deformable material (for example elastomer).

The invention also relates to an annular stator casing (for example, intermediate casing) for a turbomachine, in particular an aircraft, comprising at least one ventilation device as described previously.

The invention also relates to a turbomachine, in particular for an aircraft, comprising an annular stator casing as described previously.

The turbomachine may be a turbojet or a turboprop.

The stator housing may be from a low pressure turbine of the turbomachine.

Brief description of figures

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

FIG. 1 is a schematic view, in longitudinal section, of a turbomachine according to the invention;

Figure 2 is a schematic sectional view of a ventilation device for the turbine engine of the invention;

Figure 3 is a very schematic view of a ventilation device according to the invention;

Figure 4 is a partial schematic sectional view of the ventilation device according to a first embodiment;

Figure 5 is a schematic sectional view of the connecting members of the device of Figure 4 which adopt an angular movement;

Figure 6 is a schematic sectional view of the connecting members of the device of Figure 4 which adopt an axial movement;

Figure 7 is a partial schematic sectional view of the ventilation device according to a second embodiment.

Detailed description of the invention

In general, in the description below, the terms "longitudinal" and "axial" qualify the orientation of structural elements extending in the direction of a longitudinal axis. This axis can be confused with an axis of rotation of an engine of a turbomachine. The term “radial” qualifies an orientation of structural elements extending in a direction perpendicular to the axis. The terms “inside” and “outside”, and “inside” and “outside” are used in reference to positioning relative to the axis. Thus, a structural element extending along the axis has an inner face facing the axis and an outer surface, opposite its inner surface.

With reference to FIG. 1, a dual-flow turbomachine 1 comprises, upstream to downstream in the direction of gas flow, at least one fan 2 and a gas generator comprising one or more compressor stages, low pressure 3 and high pressure 4, a combustion chamber 5, one or more turbine stages, high pressure 6 then low pressure 7, and an exhaust nozzle 8. The rotors of the turbomachine 1 are rotatable around a longitudinal axis X ' of turbomachine 1.

The low pressure turbine 7 notably comprises a rotor comprising a plurality of vanes 9 fixed in a regular manner on a hub 10, and a stator comprising a casing 11 extending around the vanes 9 of the rotor.

The air flow driven by the fan 2 is separated into a primary air flow F1 penetrating the gas generator of the turbomachine 1 and a secondary air flow F2 participating in a preponderant manner in the thrust provided by the turbomachine 1 The secondary air flow F2 flows around the gas generator in a secondary stream 12.

The turbomachine 1 further comprises an intermediate casing 13 located longitudinally between the low pressure compressor 3 and the high pressure compressor 4, this casing 13 comprising an inner shroud 14, and an outer shroud 15 extending around the inner shroud 14 and forming with the latter a portion of the secondary vein. The outer shroud 15 is rigidly connected to the inner shroud 14 by arms 16 substantially radial with respect to the longitudinal axis X'.

The turbomachine 1 further comprises a ventilation device 17 also called LPTACC, making it possible to regulate the temperature of the casing 11 of the low pressure turbine 7, and consequently the radial clearances between the casing 11 and the blades 9 of the rotor of the low pressure turbine 7.

Referring to Figures 1 and 2, the device 17 comprises at least one passage duct 20 of the air flow F2 which extends along a first longitudinal axis X. The first axis X is substantially parallel to the axis X' of turbomachine 1.

Duct 20 includes a first portion 21 forming an air inlet and a second portion 22 forming an air outlet. For example, air intake means (not shown), such as a scoop, are mounted on the casing 11 and connected upstream of the first portion 21 so as to supply air to the device 17. The first portion is connected downstream with the second portion 22. In a non-limiting manner, the first portion 21 can be connected to one or more second portions 22 directly or via a bifurcation 23. In the example, the first portion 21 is connected to the bifurcation 23 at which this first portion 21 separates into first and second branches forming second portions 22.

The device 17 also comprises at least one air distribution box 24 into which the second portion 22 of the duct 20 opens. The box 24 may include at least one orifice 240 through which the portion 22 opens inside the box 24 Orifice 240 has an internal diameter D2.

The casing 24 comprises a plurality of annular ramps 25 arranged around the casing 11 of the low pressure turbine 7. The ramps 25 are configured to project the flow of air onto the casing 11, through perforations for example.

One of the features of the invention is that the second portion 22 is connected to the housing 24 by connecting members 30. These members 30 are configured to allow at least one of the movements of the second portion 22 vis-à-vis the box 24 following:
- an axial movement along the first axis X,
- an angular movement around the first axis X,
- an angular movement around a second longitudinal axis Y, and
- an angular movement around a third longitudinal axis Z.

The second Y and third Z axes are each perpendicular to the first X axis.

Referring to Figures 3 to 7, the members 30 include:
- a connecting piece 31 to the second portion 22 of the duct,
- a nut 32 for tightening the connecting piece 31, and
- an annular sealing device 33 between the nut 32 and the housing 24.

The connecting part 31 has a shape of revolution extending around an axis which coincides with the first axis X of the device 17. This part comprises a threaded portion 311 and an attachment portion 312 to the second portion 22 of the leads. In the figures, the attachment portion 312 has an outer diameter greater than the outer diameter of the threaded portion 311.

The nut 32 comprises a main body formed by a base 321 with an external diameter D1 (FIGS. 4 to 7). The main body can also be formed by the base 321 and a flange 322 of annular shape with an external diameter D3 (FIGS. 3 to 6). The outer diameter D1 of the base is greater than the outer diameter D3 of the collar.

The sealing device 33 may be an O-ring. The seal can be made of an elastically deformable material, such as an elastomer.

The connecting members 30 are for example of the ball-and-socket type, as shown schematically in FIG. 3. This therefore allows mobility according to the aforementioned movements. In this figure, the reference 300 denotes a ball joint which is here carried by the nut 32 and which is housed in the orifice 240 of the housing 24. Alternatively, the ball joint 300 could be carried by the connecting piece 31 and housed in the orifice 240 of the housing (not shown).

The connecting members 30 are concretely shown in FIGS. 4 to 6, illustrating a first embodiment, FIG. 7 illustrating a second embodiment.

Figure 4 partially illustrates the attachment of the members 30 to the ventilation device 17.

The second portion 22 of the duct is connected to the connecting piece 31 by the attachment portion 312. Advantageously, this connection between the second portion 22 and the piece 31 is of the sliding pivot type. This allows assembly of the second portion 22 and of the part 31 by translation along the first axis X and/or by rotation around the first axis X.

A clamp 34 can be arranged around part 31, preferably around attachment portion 312. This makes it possible to hold second portion 22 assembled with part 31 in position.

The connecting piece 31, and preferably the threaded portion 311, passes through the orifice 240 of the housing 24. The threaded portion 321 of the piece 31 is configured to receive the nut 32. In the example, the threaded portion 311 is fixed by form complementarity with a thread of the nut 32.

The nut 32 is housed in the casing 24. More particularly, the base 321 is housed through the orifice 240 in the casing 24. In the example, the external diameter D1 of the base 321 is greater than the internal diameter D2 of the orifice 240. The collar 322 of the nut passes through the orifice 240 of the housing. Thus, the external diameter D3 of the collar is substantially less than the internal diameter D2 of the orifice 240.

The sealing device 33 is interposed between the nut 32 and a peripheral edge 241 of the orifice 240. The device 33 is configured to be compressed when the second portion 22 moves axially along the first axis X, and/or to adopt the angular movement of the second portion 22 around at least one of the axes X, Y, Z.

The method of mounting the connecting members 30 on the ventilation device 17 comprises, for example, the steps consisting in:
(a) mounting the sealing device 33 on one of the elements chosen from among the nut 32 and the peripheral edge 241 of the orifice 240 of the housing 24,
(b) put the nut 32 in place through the orifice 240 using a suitable tool which passes through the inside of the nut 32,
(c) making a weld of the housing 24 on the casing 11,
(d) screw threaded portion 311 of piece 31 into nut 32, and
(e) mount by translation and/or rotation the second portion 22 of the duct 20 in the part 31 screwed to the nut 32.

Alternatively, steps (b) and (c) can be interchanged. In this case, in step (b), the tool passes through the inside of the housing 24 to fix the nut 32 in the hole 240 of the housing.

The present application now describes the operation of the ventilation device 17 of the invention in the low pressure turbine 7 of the turbomachine 1.

FIG. 5 illustrates in a non-limiting way an angular movement of the members 30 according to an angle α around the third axis Z. This angular movement can also be carried out around the axes Y and X. This allows the second portion 22 and the housing 24 to be connected together by a ball-and-socket type connection.

The sealing device 33 is configured to adopt the angular movement of the members 30 so as to ensure a seal between the inside and the outside of the device 17.

The angular displacements around the X, Y and Z axes are each of the order of +/- 10°, preferably +/- 5°, and more preferably +/- 2°.

Figure 6 illustrates an axial movement of the members 30 along the first axis X, for example induced by a tensile force in operation (represented by the arrows). This axial movement causes the compression of the sealing device 33 between the nut 32 and the peripheral edge 241 of the orifice 240 of the housing 24. The sealing device 33 can be compressed by at least 50% with respect to its volume. initial.

Figure 7 illustrates the second embodiment. The connecting members 30 are distinguished from the first embodiment by the nut 32. The main body of the nut is formed by the base 321 (without flange 321). This base 321 is comparable to the ball joint 300. This configuration is favored for large angular deflections, for example greater than +/- 5°.

The method of mounting the members 30 and its operation in the device 17 of the first embodiment can also be adapted to the connecting members 30 of the second embodiment.

In both embodiments, the connecting members make it possible to provide flexibility and mobility between the second portion of the air passage duct and the air distribution box.

The invention provides several advantages which are, in particular:
- reliably and tightly connect the air passage duct and the air distribution box,
- remove leaks from the ventilation system,
- optimize the passage of the air flow between the air passage duct and the air distribution box,
- guarantee mechanical strength under thermomechanical stress or vibratory positioning under the operating conditions of the turbomachine,
- simplify the assembly and operation of the ventilation device on the turbomachine,
- adapt easily to current turbomachines.

Overall, this proposed solution is simple, effective and economical to produce and to assemble on a turbomachine, while increasing the service life of the ventilation device in operation.

Claims (11)

Ventilation device (17) for an annular stator casing (11) of a turbine engine (1), in particular an aircraft, comprising:
- at least one passage duct (20) for an air flow (F2) of which a first portion (21) forms an air inlet and a second portion (22) forms an air outlet,
- at least one air distribution box (24) into which the second portion (22) of the conduit opens and comprising a plurality of annular ramps (25) intended to extend around the casing (11) and configured to project the air flow on the casing (11),
characterized in that the second portion (22) of the conduit is connected by connecting members (30) to the housing (24), the members (30) being configured to allow axial movement of the second portion (22) of the screw conduit -to-vis the housing (24) relative to a first longitudinal axis (X) of the conduit (20) and / or at least one angular movement of the second portion (22) of the conduit vis-à-vis the housing (24 ), around the first axis (X), a second (Y) and/or a third (Z) longitudinal axes, the second (Y) and the third (Y) axes each being perpendicular to the first axis (X ). Device according to Claim 1, characterized in that the connecting members (30) comprise a connecting piece (31) to the second portion (22) of the duct, the connecting piece (31) passing through an orifice (240) of the casing (24) and comprising a threaded portion (311) receiving a nut (32) housed in the housing (24) and an annular sealing device (33) being mounted around the threaded portion (310) and interposed between the nut (32) and a peripheral edge (241) of the orifice (240). Device according to one of the preceding claims, characterized in that the said connecting members (30) are of the ball joint type. Device according to the preceding claim, characterized in that the connecting members (30) comprise a ball joint (300) carried by the nut (32), in which at least a part of the ball joint (300) is housed in the orifice (240) of the housing (24). Device according to one of Claims 2 to 4, characterized in that the second portion (22) of the duct and the connecting piece (31) are interconnected by a sliding pivot connection. Device according to one of Claims 2 to 5, characterized in that the connecting members (30) further comprise a clamping collar (34) arranged around the connecting piece (31) and configured to hold the second portion (22) of the duct connected to the connecting piece (31). Device according to one of Claims 2 to 6, characterized in that the nut (32) comprises a base (321) arranged inside the casing (24) with an external diameter (D1) greater than an internal diameter ( D2) of the orifice (240) of the housing (24). Device according to the preceding claim, characterized in that the nut (32) further comprises a collar (322) with an external diameter (D3) smaller than the internal diameter (D2) of the orifice (240) of the casing (24) . Device according to one of Claims 2 to 8, characterized in that the sealing device (33) is an O-ring configured to be compressed between the nut and the peripheral edge (241) of the orifice (240) when the second portion (22) of the conduit moves axially along the first axis (X), and/or adopting the angular movement of the second portion (22) around the second (Y) and/or third (Z) axes. Device according to one of Claims 2 to 9, characterized in that the sealing device (33) is made of an elastically deformable material. Turbomachine (1), in particular for an aircraft, comprising a stator casing (11) comprising at least one ventilation device (17) according to one of the preceding claims.