ARRANGEMENT FOR A TURBINE ENGINE

Description

Technical field of the invention

[0001] The present invention relates to an assembly for a turbomachine, such as for example an aircraft turbojet or turboprop. State of the prior art

[0002] Such a set is known from document FR 3 004 518 in the name of the Applicant and is illustrated in figures 1 à 3 This comprises an annular combustion chamber 1 arranged downstream of a compressor, and upstream of an inlet distributor 2 of a high-pressure turbine.

[0003] The combustion chamber 1 comprises internal and external walls of revolution, called respectively internal shell 3 and external shell 4, which extend inside one another and which are connected upstream to an annular chamber bottom wall 5.

[0004] In order to limit the deformation of the inner 3 and outer 4 shells, the latter are equipped at their downstream end with inner and outer flanges 6. Each flange 6 is annular and has a U-shaped or pin-shaped section. Each flange 6 extends radially inward or outward and comprises a radial portion 7a attached to the inner shell 3 or to the outer shell 4 of the combustion chamber 1. The free end 6a of each flange 6 is further intended to cooperate with an inner casing 8 or an outer casing 9 of the chamber 1. An axial or cylindrical portion 7b extends downstream from the radial portion 7a of the flange 6.

[0005] The distributor 2 is fixed downstream of the chamber 1 by suitable means and comprises internal 11 and external 12 platforms which are connected to each other by substantially radial vanes 13. The external platform 12 of the distributor 2 is axially aligned with the downstream end portion of the external shell 4 of the chamber 1, and its internal platform 11 is axially aligned with the downstream end portion of the internal shell 3 of the chamber 1. The upstream end of each platform 11, 12 of the distributor 2 comprises a radial rim 14 of smaller dimension than the radial portion 7a of the corresponding flange 6 of the combustion chamber 1.

[0006] A distributor assembly 2 is generally mounted downstream of the combustion chamber 1 and comprises several distributors 2 whose platforms 11, 12 are ring sectors, the platforms 11, 12 of the distributors 2 being mounted circumferentially end to end to create a fluid circulation channel downstream of the combustion chamber 1.

[0007] The radial parts 7a and the rims 14 delimit, for each ferrule 3, 4, an annular space 15 which opens at a radially internal end into the chamber 1 and which is closed at its radially external end by sealing means 16.

[0008] As is best seen in the figures 2 And 3, these sealing means 16 comprise sealing strips 17 extending radially and circumferentially along each distributor sector 2. Each strip 17 is capable of bearing in a sealed manner on a radial face of the corresponding rim 14 of the distributor 2 and on the free end of the axial part 7b of the corresponding flange 6 of the combustion chamber 1. The strips 17 are held in abutment on said parts 7b, 14 using elastic return means.

[0009] These elastic means are for example helical springs or elastic blades 18, fixed by means of screws 19 which are screwed into lugs 20 extending radially from the corresponding shell 11, 12 of the distributor 2. The downstream parts 21 of the inner and outer shells 3, 4 may comprise multiple perforations. During operation of the turbomachine, bypass air 23 circulates in the spaces 24 and 25 delimited respectively by the outer casing 9 and the outer shell 4, on the one hand, and by the inner casing 8 and the inner shell 3, on the other hand. This bypass air 23 passes through the multiple perforations, so as to limit the heating of the downstream parts 21 of the inner and outer shells 3, 4.

[0010] In operation, local recirculations of the hot gas flow and poor distribution of the cooling air flows within the annular space 15 appear, which can generate premature degradation of the flanges 6, in particular at the level of the radial parts 7a of the flanges, and degradation of the platforms 1, 12 of the distributor 2.

[0011] An assembly for a turbomachine according to the preamble of claim 1 is known from document FR 3 004 518.

[0012] The invention aims in particular to provide a simple, effective and economical solution to this problem. Presentation of the invention

[0013] To this end, the invention relates to an assembly for a turbomachine extending around an axis and comprising: a combustion chamber comprising, at its downstream end, a downstream flange having a radially extending portion, a distributor arranged downstream of the combustion chamber and comprising a platform from which at least one blade extends radially, the platform comprising an upstream rim extending radially and delimiting, with the radial portion of the downstream flange arranged opposite, an annular space for the circulation of cooling air opening into the combustion chamber at its radially inner end and comprising, at its radially outer end, sealing means fixed to the distributor, the sealing means extending on the one hand against the distributor and on the other hand against the flange, characterized in that said rim of the distributor or said radial portion of the flange of the combustion chamber comprises at least one surface irregularity facing the side of the annular air circulation space,said surface irregularity being formed by a recess or a protruding area.

[0014] The presence of surface irregularities at specific locations allows for better distribution of cooling air flows within the annular cooling air circulation space so as to avoid premature deterioration of the combustion chamber flange and distributor platform.

[0015] The terms axial, radial and circumferential are defined in relation to the axis of the assembly, which is the same as the axis of the turbomachine. Furthermore, the terms upstream and downstream are defined in relation to the direction of gas flow within the turbomachine.

[0016] The recess is formed by a localized hollow area, not axially crossing the flange or the upstream edge.

[0017] The combustion chamber may comprise a radially internal annular shell and a radially external annular shell, each shell comprising a downstream flange, the distributor comprising a radially internal platform and a radially external platform connected by at least one blade, each platform comprising an upstream rim arranged opposite the downstream flange of the corresponding shell.

[0018] The radially inner and outer shells of the combustion chamber may be connected by an annular bottom wall.

[0019] The surface irregularity can be formed on each flange of the radially internal shell and / or on each rim, so as to more specifically improve the distribution of cooling air flows in these areas, which are the areas most affected by risks of degradation.

[0020] Each rim and / or the downstream flange comprises at least one recessed surface irregularity crossed by a radial reference plane, said radial reference plane being angularly offset or not with respect to a median radial plane passing through a blade of the distributor extending from the corresponding platform of the distributor.

[0021] The recess thus generates a depression zone near the distributor blade, which tends to bring the cooling air flows closer to the flange and rim areas located circumferentially at the level of said blade, where the risks of damage are greater in the absence of such a surface irregularity. In other words, such a feature ensures a more homogeneous distribution of the cooling air flow in the aforementioned annular space.

[0022] The recess may have a general shape of a portion of a sphere or a shape of a portion of a spheroid or ellipsoid of revolution. In the case where the recessed area is of a generally oblong shape, the axis of extension of said recessed area may be radial or extend circumferentially or tangentially.

[0023] Generally speaking, whatever the embodiment envisaged, the positioning of the reference plane relative to the median radial plane passing through the blade may depend in particular on the direction of rotation of the rotor in the turbomachine and the shape of the blade, in particular the leading edge of the blade.

[0024] It is recalled that a blade has an extrados surface and an intrados surface connected upstream by a leading edge and downstream by a trailing edge.

[0025] Each rim and / or flange comprises at least two projecting surface irregularities located circumferentially on either side of a radial reference plane, each surface irregularity being circumferentially offset from said radial reference plane, said radial reference plane being angularly offset or not from a median radial plane passing through a blade of the distributor extending from the corresponding platform of the distributor.

[0026] The protruding or thickened areas locally generate areas of higher pressure on either side of the area opposite the distributor blade, which makes it possible to deflect the flows so as to force the mixing by increasing the volume of air circulation locally. This also tends to bring the cooling air flows closer together in the areas of the flange and the rim located circumferentially at the level of said blade, where the risks of damage are greater in the absence of such a surface irregularity. In other words, such a characteristic ensures a more homogeneous distribution of the cooling air flow in the aforementioned annular space.

[0027] Each protruding area may have a rounded shape. Each protruding area may have an oblong shape extending along an axis. Said extension axis of each protruding area may form an angle with the radial direction. The protruding areas located on either side of the reference plane may be inclined relative to each other and relative to the radial reference plane and may move closer to each other in the direction of the blade. The downstream flange may comprise at least one cooling air circulation orifice extending at least axially and opening into said annular air circulation space, opposite the corresponding upstream rim.

[0028] The air passing through said orifices can thus cool the upstream edge of the distributor platform by impact.

[0029] The upstream rim and / or the downstream flange comprises a recessed surface irregularity located in a radial reference plane, said radial reference plane being angularly offset or not with respect to a median radial plane passing through the cooling air circulation orifice.

[0030] The reference radial plane may coincide with the median radial plane passing through the cooling air circulation orifice.

[0031] The recess thus generates a depression zone opposite the orifice, which ensures a more homogeneous distribution of the cooling air flow in the aforementioned annular space. The upstream rim and / or the downstream flange may comprise at least two projecting surface irregularities located circumferentially on either side of a radial reference plane, each surface irregularity being circumferentially offset relative to said radial reference plane, said radial reference plane being angularly offset or not relative to a median radial plane passing through the cooling air circulation orifice.

[0032] The protruding zones locally generate zones of higher pressure on either side of the orifice and deflect the flows so as to force the mixing by increasing the volume of air circulation locally, which ensures a more homogeneous distribution of the cooling air flow in the aforementioned annular space.

[0033] The sealing means may comprise at least one strip extending radially and circumferentially, and bearing axially on the flange of the combustion chamber and on the upstream edge of the distributor.

[0034] The distributor may be annular and may comprise several adjacent angular sectors distributed around the circumference.

[0035] The support of the blade on the flange and on the upstream edge can be an axial support.

[0036] The upstream rim may extend radially. The strip may bear on a downstream radial face of the upstream rim. The flange may include an axial portion, the downstream end of said axial portion may form a radial bearing face serving to support the strip.

[0037] The invention also relates to a turbomachine comprising an assembly of the aforementioned type.

[0038] The invention also relates to an aircraft comprising a turbomachine of the aforementioned type or an assembly of the aforementioned type. Brief description of the figures

[0039] [ Fig. 1 ] is an axial sectional view of a prior art turbomachine assembly, [ Fig. 2 ] is a detail view of part of the figure 1 , [ Fig. 3 ] is a detail view of part of the figure 1 , [ Fig. 4 ] is a schematic view of a distributor sector, [ Fig. 5 ] is a schematic view of the upstream edge of a distributor sector according to a first embodiment of the invention, [ Fig. 6 ] is a schematic view of the upstream edge of a distributor sector according to a second embodiment of the invention, [ Fig. 7 ] is a schematic view of the upstream edge of a distributor sector according to a third embodiment of the invention, [ Fig. 8 ] is a schematic view of the upstream edge of a distributor sector according to a fourth embodiment of the invention. Detailed description of the invention

[0040] There figure 4 illustrates an angular distributor sector 2 of an assembly according to the invention. This comprises a radially internal platform sector 11 and a radially external platform sector 12, connected to each other by radially extending blades 13, here two blades 13. Each blade 13 comprises an intrados surface and an extrados surface connected to each other upstream by a leading edge and downstream by a trailing edge.

[0041] Several such sectors may be fixed adjacently or contiguously so as to form an annular distributor 2.

[0042] On the figure 4 and the following figures, the platforms 11, 12 are represented in a rectilinear manner although they actually have the shape of ring sectors.

[0043] THE figures 4 and following represent only the upstream edges 14 of the radially internal platforms 11 of the distributor sectors 2.

[0044] Each blade 13 extends along a median radial plane P1, the position of which is illustrated by dotted lines at figures 4 And 5 .

[0045] In the embodiment of the figure 5 , the upstream rim 14 comprises, for each blade 13, two surface irregularities formed by two oblong projecting zones 26 located on either side of a radial reference plane P2, each surface irregularity 26 being circumferentially offset relative to said radial reference plane P2. The radial reference plane P2 is angularly offset or not relative to the median radial plane P1 passing through the corresponding blade 13 of the distributor 2.

[0046] The positioning of the reference plane P2 relative to the median radial plane P1 passing through the blade 13 depends in particular on the direction of rotation of the rotor in the turbomachine and the shape of the blade 13, in particular the leading edge of the blade 13.

[0047] The extension axis 27 of each projecting area 26 forms an angle with the radial direction or the plane P2. The projecting areas 26 located on either side of the reference plane P2 are inclined relative to each other and relative to the radial reference plane P2 and approach each other in the direction of the blade 13, i.e. upwards at the figure 5 .

[0048] Only two protruding areas 26 are shown on the figure 5 . As previously indicated, the upstream rim 14 actually comprises a pair of projecting zones 26 for each blade 13 of the distributor 2.

[0049] In operation, the projecting zones 26 locally generate zones of higher pressure on either side of the zone located opposite 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 the rim 14 located circumferentially at the level of said blade 13, where the risks of degradation are greater in the absence of such a surface irregularity. In other words, such a characteristic ensures a more homogeneous distribution of the cooling air flow in the annular space 15 for the circulation of cooling air, located 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 the platform 11 of the distributor 2.

[0050] There figure 6 illustrates another embodiment in which the upstream rim 14 comprises, for each blade 13, a recessed surface irregularity 27, located in a radial reference plane P2. The radial reference plane P2 is angularly offset or not relative to the median radial plane P1 passing through the corresponding blade 13 of the distributor 2.

[0051] In operation, the recess 27 thus generates a depression zone near the blade 13 of the distributor 2, which tends to bring the cooling air flows closer together in the areas of the flange 6 and the rim 14 located circumferentially at the level of said blade 13, where the risks of damage are greater in the absence of such a surface irregularity. In other words, such a characteristic ensures a more homogeneous distribution of the cooling air flow in the aforementioned annular space 15.

[0052] The recess 27 may have a general shape of a portion of a sphere or a shape of a portion of a spheroid or ellipsoid of revolution. In the case where the recessed area 27 is of a generally oblong shape, the axis of extension of said recessed area 27 may be radial or may extend circumferentially or tangentially.

[0053] THE figures 7 et 8 illustrate embodiments in which the flange 6 comprises orifices 29 for the passage of cooling air. The cooling air from said orifices 29 makes it possible to cool by impact the corresponding upstream rim 14 of the distributor 2 but generates heterogeneities in the distribution of the cooling air flows. The circumferential positions of the orifices 29 are represented by dotted lines on the figures 7 et 8 .

[0054] In order to limit such heterogeneity, in the embodiment of the figure 7 , the upstream rim 14 comprises, for each orifice 29, a recess 27 located in a radial reference plane P2 which coincides with the median plane P3 passing through the cooling air circulation orifice 29. The orifice 29 of the impact jet is sized and arranged so as to cool the upstream rim 14.

[0055] The recess 27 thus generates a depression zone opposite the orifice 29, which ensures a more homogeneous distribution of the cooling air flow in the aforementioned annular space.

[0056] There figure 8 illustrates an alternative embodiment, which differs from that described with reference to the figure 7 in that the upstream rim 14 comprises two projecting surface irregularities 26 each located in a plane 28 and located circumferentially on either side of the median plane P3 of each orifice 29.

[0057] In other words, the protruding areas 26 are distributed circumferentially between the circumferential positions of the orifices 29.

[0058] The projecting zones 26 locally generate zones of higher pressure on either side of the circumferential position of each orifice 29, which ensures a more homogeneous distribution of the cooling air flow in the aforementioned annular space 15.

[0059] Generally, the overthicknesses or protruding areas 26 direct the cooling flow by causing it to deflect. The invention thus makes it possible to direct the cooling flow towards the usually hot areas in order to reduce the temperature of the metal. The air is then expelled towards the vein by pressure differential, from the area located outside said vein into the vein.

[0060] Furthermore, the under-thicknesses or recesses 27 increase the volume of air circulation, and create a local area of ​​slight depression, drawing in the air nearby. In this way, the area is locally better cooled because the air there is cooler. The air is then expelled towards the vein by pressure differential, from the area located outside said vein into the vein.

Claims

1. An assembly for a turbomachine extending about an axis and comprising: - a combustion chamber (1) comprising, at its downstream end, a downstream flange (6) having a radially extending part (7a), - a distributor (2) disposed downstream of the combustion chamber (1) and having a platform (11, 12) from which at least one vane (13) extends radially, the platform (11, 12) comprising an upstream rim (14) extending radially and delimiting, with the radial part (7a) of the flange (6) disposed opposite it, an annular space (15) for the circulation of cooling air opening into the combustion chamber (1) at its radially internal end and having, at its radially external end, means of sealing (17, 18) attached to the distributor (2), the means of sealing extending, firstly, against the distributor (2) and, secondly, against the flange (6) characterized in that the said rim (14) of the distributor (2) or the said radial part of the flange (6) of the combustion chamber (1) has at least one surface irregularity facing the side of the annular space (15) for the circulation of air, the said surface irregularity being formed by a recess (27) or a protruding zone (26), and in that each rim (14) and / or each downstream flange (6) comprises: either at least one recessed surface irregularity (27) 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 one of the at least one vane (13) of the distributor (2) extending from the corresponding platform (11, 12) of the distributor (2), or at least two projecting surface irregularities (26) situated 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 one of the at least one vane (13) of the distributor (2) extending from the corresponding platform (11, 12) of the distributor (2).

2. An assembly according to claim 1, characterised in that the combustion chamber (1) has an annular radially internal shroud (3) and an annular radially external shroud (4), each shroud (3, 4) having a downstream flange (6), the distributor (2) having a radially internal platform (11) and a radially external platform (12) connected by at least one of the at least one vane (13), each platform having an upstream rim (14) disposed opposite the downstream flange (6) of the corresponding shroud.

3. An assembly according to claim 2, characterized in that the surface irregularity (26, 27) is formed on each flange (6) of the radially internal shroud (3) and / or on each rim (14).

4. An assembly according to one of claims 1 to 3, characterized in that each flange (6) comprises at least one orifice (29) for the circulation of cooling air which extends at least axially and opens into the said annular space (15) for the circulation of air, facing the corresponding rim (14).

5. An assembly according to claim 4, characterized in that each flange (6) has at least two projecting surface irregularities (26) situated 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 (P3) passing through the orifice (29) for the circulation of cooling air.

6. An assembly according to one of claims 4 or 5, characterized in that each rim (14) and / or each flange (6) comprises at least two recessed surface irregularities situated circumferentially on either side of a radial reference plane (P2) , each surface irregularity being circumferentially offset with respect to the said reference plane (P2) being angularly offset, or not, with respect to a median radial plane (P3) passing through the orifice (29) for the circulation of cooling air.

7. An assembly according to one of claims 1 to 6, characterized in that the means of sealing (16) comprise at least one strip (17) extending radially and circumferentially, and bearing axially on the flange (6) of the combustion chamber (1) and on the upstream rim (14) of the distributor (2).

8. A turbomachine comprising at least an assembly according to one of claims 1 to 7.