ASSEMBLY FOR A TURBINE ENGINE

Abstract

An assembly for a turbomachine extending along an axis includes a combustion chamber having, at its downstream end, a downstream flange having a radially extending part. The assembly further includes a distributor disposed downstream of the combustion chamber and having a platform from which at least one vane extends radially. The platform includes an upstream flange extending radially and delimiting, with the radial part of the downstream flange disposed opposite it. An annular space for the circulation of cooling air opens into the combustion chamber at its radially internal end and has, at its radially external end, means of sealing attached to the distributor.

Claims

1. An assembly for a turbomachine extending about an axis and comprising: a combustion chamber comprising, at its downstream end, a downstream flange having a radially extending part , and a distributor disposed downstream of the combustion chamber and having a platform from which at least one vane extends radially, the platform comprising an upstream rim extending radially and delimiting, with the radial part of the flangedisposed opposite it, an annular space configured for the circulation of cooling air opening into the combustion chamber at its radially internal end and having, at its radially external end, means of sealing attached to the distributor, the means of sealing extending, firstly, against the distributor and, secondly, against the flange wherein the said rimof the distributor or the said radial part of the flange of the combustion chamber has at least one surface irregularity facing the side of the annular spacem for the circulation of air, the said surface irregularity being formed by a recess or a protruding zone .

2. The assembly according to claim 1, wherein the combustion chamber has an annular radially internal shroud and an annular radially external shroud , each shroud having a downstream flange, the distributor having a radially internal platform and a radially external platform connected by at least one vane, each platform having an upstream rim disposed opposite the downstream flange of the corresponding shroud.

3. The assembly according to claim 2, wherein the surface irregularity is formed on each flange of the radially internal shroud and/or on each rim.

4. The assembly according to claim 1, wherein each rim and/or each downstream flange has at least one recessed surface irregularity traversed by a radial reference plane (P2), the said radial reference plane (P2) being angularly offset, or not, with respect to a median radial plane (P1) passing through a blade of the distributor extending from the corresponding platform of the distributor.

5. The assembly according to claim 1, wherein each rim and/or the flange has at least two projecting surface irregularitiessituated circumferentially on either side of a radial reference plane (P2), each surface irregularity being offset circumferentially with respect to the said radial reference plane (P2), the said radial reference plane (P2) being angularly offset, or not, with respect to a median radial plane (P1) passing through a distributor blade extending from the corresponding platform of the distributor.

6. The assembly according to claim 1, wherein each flange comprises at least one orifice configured for the circulation of cooling air which extends at least axially and opens into the said annular space for the circulation of air, facing the corresponding rim.

7. The assembly according to claim 6, wherein each rimand/or each flange comprises a recessed surface irregularity situated in a radial reference plane (P2), the said radial reference plane (P2) being angularly offset, or not, with respect to a median radial plane (P3) passing through the orifice for the circulation of cooling air.

8. The assembly according to claim 6 wherein each rim and/or each flange comprises at least two projecting surface irregularities situated circumferentially on either side of a radial plane (P2), each surface irregularity being offset circumferentially with respect to the said radial reference plane (P2), the said radial reference plane (P2) being angularly offset, or not, with respect to a median radial plane (P3) passing through the orifice for the circulation of cooling air.

9. The assembly according to claim 1, wherein the means of sealing comprise at least one strip extending radially and circumferentially, and bearing axially on the flange of the combustion chamber and on the upstream rim of the distributor.

10. A turbomachine comprising at least one assembly according to claim 1.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0038] FIG. 1 is an axial cross-sectional view of a prior art turbomachinery assembly,

[0039] FIG. 2 is a detail view of a part of FIG. 1,

[0040] FIG. 3 is a detail view of a part of FIG. 1,

[0041] FIG. 4 is a schematic view of a distributor sector,

[0042] FIG. 5 is a schematic view of the upstream rim of a distributor sector according to a first embodiment of the invention,

[0043] FIG. 6 is a schematic view of the upstream rim of a distributor sector according to a first embodiment of the invention,

[0044] FIG. 7 is a schematic view of the upstream rim of a distributor sector according to a first embodiment of the invention,

[0045] FIG. 8 is a schematic view of the upstream rim of a distributor sector according to a first embodiment of the invention.

DETAILED DESCRIPTION OF THE INVENTION

[0046] FIG. 4 illustrates an angular distributor sector 2 of an assembly according to the invention. This has a radially internal platform sector 11 and a radially external platform sector 12, connected to each other by radially extending vanes 13, here two vanes 13. Each vane 13 has a lower surface and an upper surface connected to each other upstream by a leading edge and downstream by a trailing edge.

[0047] A number of such sectors can be attached adjacent or contiguous to form an annular distributor 2.

[0048] In FIG. 4 and the following figures, the platforms 11, 12 are shown in a straight line, although they are actually in the form of ring sectors.

[0049] FIG. 4 and following show only the upstream rims 14 of the radially internal platforms 11 of the distributor sectors 2. Each blade 13 extends along a median radial plane P1, the position of which is illustrated by dotted lines in FIGS. 4 and 5.

[0050] In the embodiment shown in FIG. 5, the upstream rim 14 has, for each blade 13, two surface irregularities formed by two oblong projecting zones 26 situated on either side of a radial reference plane P2, each surface irregularity 26 being circumferentially offset with respect to the said radial reference plane P2. The radial reference plane P2 is angularly offset, or not, with respect to the median radial plane P1 passing through the corresponding blade 13 of the distributor 2.

[0051] The positioning of the reference plane P2 in relation to the median radial plane P1 passing through the blade 13 depends on the direction of gyration of the rotor in the turbomachine and on the shape of the blade 13, in particular the leading edge of the blade 13.

[0052] The axis of extension 27 of each projecting zone 26 is at an angle to the radial direction or plane P2. The projecting zones 26 situated on either side of the reference plane P2 are inclined to each other and to the radial reference plane P2 and approach each other in the direction of the blade 13, i.e. upwards in FIG. 5.

[0053] Only two projecting zones 26 are shown in FIG. 5. As previously specified, the upstream rim 14 actually has a pair of projecting zones 26 for each blade 13 of the distributor 2.

[0054] In operation, the protruding zones 26 locally generate zones of higher pressure on either side of the zone facing the blade 13 of the distributor 2, which tends to bring the cooling-air flows closer together in the zones of the flange 6 and rim 14 circumferentially situated at the level of the said blade 13, where the risks of damage are greater in the absence of such a surface irregularity. In other words, such a feature ensures a more even distribution of the cooling-air flow in the annular space 15 of the cooling-air circulation, situated axially between the corresponding downstream flange 6 of the combustion chamber 1 and the aforementioned upstream rim 14, so as to avoid premature degradation of the flange 6 of the combustion chamber 1 and of the platform 11 of the distributor 2.

[0055] FIG. 6 illustrates a further embodiment in which the upstream rim 14 has, for each blade 13, a recessed surface irregularity 27, situated in a radial plane of reference P2. The radial reference plane P2 is angularly offset, or not, with respect to the median radial plane P1 passing through the corresponding blade 13 of the distributor 2.

[0056] The recess thus generates a zone of negative pressure in the vicinity of the distributor blade, which tends to bring cooling airflows closer together in the flange zones and rim zones situated circumferentially at the said blade, where the risk of degradation is greater in the absence of such surface irregularity. In other words, such a feature ensures a more even distribution of the cooling-air flow in the aforementioned annular space.

[0057] The recess can have a general shape of a part of a sphere or a shape of a part of a spheroid or ellipsoid of revolution. In the case where the recessed zone is generally oblong in shape, the axis of extension of the said recessed zone can be radial or extend circumferentially or tangentially.

[0058] FIGS. 7 and 8 illustrate embodiments in which the flange 6 has orifices 29 for the passage of cooling air. The cooling air from the aforementioned orifices 29 cools the corresponding upstream rim 14 of the distributor 2 by impact, but generates heterogeneities in the distribution of the cooling-air flows. The circumferential positions of the orifices 29 are represented by dotted lines in FIGS. 7 and 8.

[0059] In order to limit such heterogeneity, in the embodiment shown in FIG. 7, the upstream rim 14 has, for each orifice 29, a recess 27 situated in a radial reference plane P2 which coincides with the median plane P3 passing through the orifice for the circulation of cooling air 29. The impact jet orifice 29 is sized and disposed to cool the upstream rim 14.

[0060] The recess thus creates a zone of negative pressure opposite the orifice, which ensures a more even distribution of the cooling-air flow in the aforementioned annular space.

[0061] FIG. 8 illustrates an alternative embodiment, which differs from that described with reference to FIG. 7 in that the upstream rim 14 has two projecting surface irregularities 26 each situated in a plane 28 and situated circumferentially on either side of the median plane P3 of each orifice 29.

[0062] In other words, the projecting zones 26 are distributed circumferentially between the circumferential positions of the orifices 29.

[0063] The protruding zones 26 locally generate zones of higher pressure on either side of the circumferential position of each orifice 29, thus ensuring a more even distribution of the cooling-air flow in the aforementioned annular space 15.

[0064] In general, the extra thicknesses or protruding zones 26 direct the cooling flow by deflecting it. The invention thus makes it possible to direct the cooling flow towards the usually hot zones in order to reduce the temperature of the metal. The air is then expelled into the vein by pressure differential from the zone situated outside the said vein into the vein.

[0065] In addition, the sub-thicknesses or recesses 27 increase the volume of air circulation and create a local zone of slight negative pressure, drawing in the nearby air. In this way, the zone is locally cooled better because the air is cooler. The air is then expelled into the vein by pressure differential from the zone situated outside the said vein into the vein.