Turbine engine, such as a turbojet or a turboprop engine

Abstract

A turbine engine, a turbojet, or a turboprop engine, including an annular combustion chamber defined by an inner shell and an outer shell, a turbine distributor arranged downstream of the combustion chamber, with a downstream end of the outer shell and/or of the inner shell of the chamber including a radial rim arranged opposite a radial rim of an upstream end of the distributor, a sealing mechanism including at least one strip extending between the rims to provide a seal between the combustion chamber and the distributor. The sealing strip extends axially and circumferentially between the rims and bears sealingly against free ends of the rims.

Claims

1. A turbomachine comprising: an annular combustion chamber defined by an inner shell and an outer shell; a turbine distributor arranged downstream of the annular combustion chamber; a downstream end of the outer shell or of the inner shell of the annular combustion chamber comprising a first radial rim arranged opposite a second radial rim of an upstream end of the turbine distributor, the first radial rim being an integral part of the annular combustion chamber and the second radial rim being an integral part of the turbine distributor, each of the first radial rim and the second radial rim including a proximal end and a distal end, the first radial rim and the second radial rim extending in a radial direction from the proximal end to the distal end; and a sealing mechanism comprising a sealing strip extending between the first radial rim and the second radial rim to provide a seal between the annular combustion chamber and the turbine distributor; a positioning lug; and a cover extending circumferentially and axially, to cover at least partially the first radial rim of the annular combustion chamber and the second radial rim of the turbine distributor and the sealing strip, wherein the sealing strip extends axially and circumferentially between the first radial rim and the second radial rim and bears against the distal end of the first radial rim and the distal end of the second radial rim, wherein one end of the positioning lug engages a notch of the sealing strip to immobilize the sealing strip in a circumferential direction of the sealing strip and in an axial direction of the turbomachine, and wherein the cover is fastened using the positioning lug, the positioning lug defined as a screw or a rivet.

2. The turbomachine according to claim 1, wherein the distal end of the first radial rim of the annular combustion chamber is axially opposite the distal end of the second radial rim of the turbine distributor.

3. The turbomachine according to claim 1, further comprising a helical spring to stress the sealing strip bearing against the distal ends of the first radial rim and the second radial rim.

4. The turbomachine according to claim 1, wherein an elastic return mechanism comprises at least one radially acting elastic member bearing against the cover and against the sealing strip.

5. The turbomachine according to claim 1, wherein the turbine distributor is sectorized to form a plurality of distributor sectors, with the sealing strip and/or the cover extending circumferentially along each of the distributor sectors.

6. A turbomachine comprising: an annular combustion chamber defined by an inner shell and an outer shell; a turbine distributor arranged downstream of the annular combustion chamber; a downstream end of the outer shell or of the inner shell of the annular combustion chamber comprising a first radial rim arranged opposite a second radial rim of an upstream end of the turbine distributor, the first radial rim being an integral part of the annular combustion chamber and the second radial rim being an integral part of the turbine distributor, each of the first radial rim and the second radial rim including a proximal end and a distal end, the first radial rim and the second radial rim extending in a radial direction from the proximal end to the distal end; and a sealing mechanism comprising a sealing strip extending between the first radial rim and the second radial rim to provide a seal between the annular combustion chamber and the turbine distributor; a positioning lug; and a cover extending circumferentially and axially, to cover at least partially the first radial rim of the annular combustion chamber and the second radial rim of the turbine distributor and the sealing strip, wherein the sealing strip extends axially and circumferentially between the first radial rim and the second radial rim and bears against the distal end of the first radial rim and the distal end of the second radial rim, wherein one end of the positioning lug engages a notch of the sealing strip to immobilize the sealing strip in a circumferential direction of the sealing strip and in an axial direction of the turbomachine, and wherein the cover has a generally U-shaped section comprising a base extending axially and a first flank extending radially inwards from the base, and a second flank extending radially inwards from the base, respectively the first flank extending radially upstream of the first radial rim of the annular combustion chamber and the second flank extending radially downstream of the second radial rim of the turbine distributor.

7. The turbomachine according to claim 6, wherein the second flank is fastened to a flange of the turbine distributor, with the first flank being separated from the first radial rim of the downstream end of the annular combustion chamber by less than 3 mm and more than 0 mm.

Description

(1) The invention shall be better understood and other details, characteristics and advantages of the invention shall appear when reading the following description provided as a non-restricted example in reference to the annexed drawings wherein:

(2) FIG. 1 is a longitudinal cross-section half-view of a portion of a combustion chamber and of a turbine distributor of a turbine engine of prior art,

(3) FIG. 2 is a perspective view of a portion of the chamber and of the distributor of FIG. 1, provided with sealing means,

(4) FIG. 3 is a detailed and cross-section view, showing the sealing means of prior art located between the outer shell of the combustion chamber and the outer shell of the distributor,

(5) FIG. 4 is a detailed and cross-section view, showing the sealing means of prior art located between the inner shell of the combustion chamber and the inner shell of the distributor,

(6) FIG. 5 is a view corresponding to FIG. 2, showing an embodiment of the invention,

(7) FIG. 6 is a perspective view of a portion of the outer shells of the chamber and of the distributor of FIG. 4, provided with associated sealing means,

(8) FIG. 7 is a perspective view of a portion of the inner shells of the chamber and of the distributor of FIG. 4, provided with associated sealing means,

(9) FIG. 8 is a detailed and cross-section view, of a portion of the outer shells of the chamber and of the distributor of FIG. 4, provided with associated sealing means,

(10) FIG. 9 is a detailed and cross-section view, of a portion of the inner shells of the chamber and of the distributor of FIG. 4, provided with associated sealing means.

(11) Reference is first made to FIG. 1 which shows a portion of an annular combustion chamber 1 of a turbine engine of prior art, such as a turbojet or a turboprop engine, which is arranged downstream of a compressor and of a diffuser (not shown), and upstream of an inlet distributor 2 of a high-pressure turbine.

(12) The combustion chamber 1 comprises inner and outer walls of revolution, referred to respectively as inner shell 3 and outer shell 4, which extend inside one another and which are connected upstream to a chamber bottom annular wall (not shown).

(13) In order to limit the deformation of the inner 3 and outer 4 shells, the latter are provided at their downstream end with inner and outer bearing members 6. Each bearing member 6 is annular and has a section in the shape of a U or in the shape of a hairpin. Each bearing member 6 extends radially inwards or outwards, between a rim 7 of the inner shell 3 or of the outer shell 4 of the combustion chamber 1 and an inner casing 8 or an outer casing 9 of the chamber 1.

(14) More particularly, the downstream end of each shell 3, 4 of the combustion chamber 1 comprises a rim 7 comprising a radial portion 7a extended by a cylindrical portion 7b extending downstream.

(15) The distributor 2 is fastened downstream of the chamber 1 by suitable means and comprises annular inner 11 and outer 12 shells that extend inside one another and which are connected together by substantially radial blades 13. The outer shell 12 of the distributor 2 is axially aligned with the downstream end portion of the outer shell 4 of the chamber 1, and its inner shell 11 is axially aligned with the downstream end portion of the inner shell 3 of the chamber 1. The upstream end of each shell 11, 12 of the distributor 2 comprises a radial rim 14 of a dimension that is more reduced than the radial portion 7a of the corresponding rim 7 of the combustion chamber 1.

(16) This distributor 2 is sectorised and forms several contiguous sectors on a circumference centred on the axis of revolution A of the chamber 1. The distributor sectors are for example in the number of fourteen.

(17) The inner rims 7, 14 of the inner shells 3, 11 of the chamber 1 and of the distributor 2 delimit an inner annular space 15 that opens at one end in the chamber 1 and which is closed at its other end by sealing means 16.

(18) Likewise, the outer rims 7, 14 of the outer shells 4, 12 of the chamber 1 and of the distributor 2 delimit an external annular space 15 that opens at one end in the chamber 1 and which is closed at its other end by sealing means 16.

(19) The sealing means 16 located on annular spaces 15 shall be described in what follows.

(20) As can be seen better in FIGS. 2 to 4, these sealing means 16 comprise sealing strips 17 extending radially and circumferentially along each distributor sector 2. Each strip 17 bears sealingly against a radial face of the corresponding rim 14 of the distributor 2 and on the free end of the axial portion 7b of the corresponding rim 7 of the combustion chamber 1. The strips 17 are maintained against the rims 7, 14 using means of elastic return.

(21) These elastic means are helical springs 18 of tapered shape, mounted around screws 19 which are screwed into the brackets 20 or flanges extending radially from the corresponding shell 11, 12 of the distributor 2. The shrunk portion of each spring 18 bears against a radial face of the corresponding bracket 20, with the widened portion bearing against the sealing strip 17. The ends of the screws 19 are engaged into the holes of the sealing strip 17, in such a way as to provide for its maintaining in position.

(22) As indicated hereinabove, the use of such sealing means 19 increases the overall mass, reduces the lifespan of the combustion chamber 1 and penalises the overall performance of the turbine engine.

(23) Furthermore, the bearing members 6 have a substantial mass and can be the location for the appearance of cracks or fissures caused by thermal and/or mechanical stresses. Finally, functional clearances must be defined with precision between the bearing members 6 and the inner and outer casings 8, 9 against which they bear.

(24) FIGS. 5 to 9 show a portion of a turbine engine according to the invention. In these figures, the bearing members 6 are not necessarily shown, in order to facilitate the comprehension of the drawings.

(25) As can be seen better in FIGS. 8 and 9 in the invention, the rims 7 of the inner 3 and outer 4 shells of the combustion chamber 1 extend radially and are devoid of axial portion. The free end of each rim 7 is located radially opposite the free end of the corresponding radial rim 14 of the distributor 2. A sealing strip 17 extends axially and circumferentially, on each distributor sector 2, between said radial rims 7, 14 and bears sealingly against the faces of the free ends of said rims 7, 14.

(26) The sealing strip 17 comprises notches 21 that open onto its downstream edge, wherein are engaged the ends of the screws 19 fastened onto the brackets 20 of the distributor 2, in such a way as to immobilise the strip 17.

(27) These screws 19 are also used to fasten a cover 22 extending circumferentially and axially, in such a way as to cover, at least partially, the corresponding rims 7, 14 of the chamber 1 and of the distributor 2 as well as the sealing strip 17.

(28) The cover 22 has a generally U-shaped section comprising a base 22a extending axially and two flanks 22b, 22c extending radially inwards from the base 22a, respectively a first flank 22b extending radially upstream of the rim 7 of the combustion chamber 1 and a second flank 22c extending radially downstream of the rim 14 of the distributor 1.

(29) The second flank 22c is fastened to the brackets 20 of the distributor 2 using screws 19 and nuts 23. The first flank 22b is separated from the rim of the downstream end of the combustion chamber 1 by a determined clearance j (FIG. 8), for example less than 3 mm. Such a clearance makes it possible to offset any dilatation effects and as well as prevent the cover 22 from being deformed by the bearing of the rim 7 of the combustion chamber 1 on the first flank 22b.

(30) Means of elastic return that stresses the sealing strip 17 to bear against the free ends of the rims 7, 14. These means of return comprise helical compression springs 18 of which one end is bearing against the strip 17 and of which the other end is bearing against the base 22a of the cover 22. The springs 18 are mounted around screws or lugs 24 fastened in the base 22a of the cover 22.

(31) The free ends of the rims 7 and/or 14 comprise grooves. The strip 17 can extend only axially (embodiment of FIG. 9) or comprises hollow zones 25 that hug the shapes of the free ends of the rims 7, 14 having grooves (embodiment of FIG. 8).

(32) The presence of the grooves makes it possible to prevent any deterioration of the strips 17.

(33) Note that, in the embodiment of FIG. 9, the strips 17 allow for a grand axial displacement of the combustion chamber 1 in relation to the distributor 2, without penalising the performance of the sealing means 16. The presence of hollow zones 25 makes it possible to better support a radial offset between the rims 7, 14 and therefore a slight pivoting of the strip 17 around the ends that have the grooves.

(34) Note that, in the invention, the radial dimensions of the rims 7 of the combustion chamber 1 are reduced and that the bearing members 6 are not necessarily reduced, which has for effect to reduce the overall mass and to reduce the exchange surfaces with the by-pass air 26 (FIG. 1). The temperature of the downstream end of the corresponding shell 3, 4 of the combustion chamber 1 is as such increased, in such a way that the temperature differences within this shell 3, 4 and the bending stresses that stem from it are substantially reduced.

(35) In addition, as the sealing strip 17 is oriented axially, at least in its bearing zones on the aforementioned rims 7, 14, it always provides a good seal, even in the case of axial displacement of the combustion chamber 1 in relation to the turbine distributor 2. The output of the turbine engine is as such increased.

(36) The cover 22 makes it possible to further reduce the thermal exchanges between the downstream end of the corresponding shell 3, 4 of the combustion chamber 1 and the by-pass air 26. This cover 22 can be perforated on its base 22a and on its second flank 22c, as can be seen in FIGS. 5 to 7. On the contrary, the first flank 22b is more preferably continuous and devoid of an opening, in such a way as to limit the cooling of the downstream end of the corresponding shell 3, 4 of the combustion chamber 1 by the by-pass airflow 26 directed from the upstream downstream and directly affecting the first flank 22b.