Turbomachine combustion chamber

Abstract

The present document relates to an annular combustion chamber of a turbomachine comprising: - an inner annular wall (14) and an outer annular wall (16); - an annular chamber bottom (17) comprising a plurality of first openings (20) for the passage of injector heads; - at least one deflector (100) arranged downstream of the chamber bottom (17), said deflector comprising at least one fixing stud (106) comprising a zone fixed to said chamber bottom, in which said fixing stud (106) comprises an internal cooling circuit (112) passing through at least a portion of said fixing stud (106) and opening upstream of the annular chamber bottom (17). Figure to be published with the abstract: [Fig. 4]

Description

Title of the invention: Turbomachine combustion chamber Technical field of the invention

[0001] This document relates to a turbomachine combustion chamber and more particularly to such a chamber equipped with a plurality of thermal deflectors. State of the prior art

[0002] Conventionally, a turbomachine with a longitudinal axis A comprises an annular combustion chamber which receives upstream an air flow from a high-pressure compressor and delivers downstream a flow of hot gases driving the rotors of the high-pressure and low-pressure turbines. In this document, the term "upstream" (AM) and the term "downstream" (AV) are understood to relate to the flow of air flows in the turbomachine.

[0003] As shown in [Fig.l], the annular combustion chamber 10 is surrounded by an outer casing 12 and comprises two coaxial annular walls, inner 14 and outer 16, which extend one inside the other and which are connected at their upstream ends by an annular chamber bottom 17. The annular combustion chamber 10 also comprises an upstream annular fairing 24 fixed to the annular chamber bottom 17 and intended to direct the air flow into or around the combustion chamber 10.

[0004] This annular chamber bottom 17 comprises a radial annular wall comprising first openings 20 for mounting fuel injection systems 22. The injection system and its connection to the annular chamber bottom will be better described with reference to [Fig.2]. Each injection system 22 comprises an injector 26 extending along a longitudinal axis D, means for mixing air with the fuel 28 and a fastening ring 30. The injector 26 is placed in one of the first openings 20. A clamping ring holds said fastening ring 30, the radially external end 32 of which is capable of sliding radially in an annular housing 34 formed at the upstream end of a Venturi effect part 36. The means for mixing air with the fuel 28 comprise said Venturi effect part 36 and a mixing bowl 38. The Venturi effect part 36 and the mixing bowl 38 may form a single part or be in two parts.The Venturi effect part 36 comprises a first upstream annular spiral 40 and a second downstream annular spiral 42. The first upstream annular spiral 40 allows air to be introduced into the venturi 36 itself while the second downstream annular spiral 42 allows air to be introduced around the Venturi effect part 36. The downstream end 44 of the Venturi effect part 36 is connected to the upstream end 46 of the mixing bowl 38. The . mixing bowl 38 further comprises a frustoconical annular wall 48 with a section increasing downstream and connected at its downstream end to a collar 50 extending radially outwards. The downstream end of the frustoconical wall is connected to a substantially cylindrical wall 52 whose upstream end is connected to a radial rim 54 fixed with a radial annular rim 56 of a thermal protection screen 58, also called a deflector, arranged downstream of the annular chamber bottom 17.

[0005] Each thermal protection screen 58 is annularly secured to the outer periphery of the mixing bowl 38, relative to the longitudinal axis D, and comprises a second opening aligned with the axis of an injector 26 and one of the first openings 20 of the chamber bottom. Each thermal protection screen 58 is brazed onto the periphery 66 of one of the first openings 20 of the radial annular wall of the annular chamber bottom 17.

[0006] The combustion chamber, by its function, is subjected to very high temperatures and thermal gradients, which can reach 1200°C to 2000°C. To protect the walls, a fraction of the air flow coming from the high-pressure compressor is used for their cooling. The annular chamber bottom 17 comprises, for the purpose of being cooled, a plurality of holes 62 on the radial annular wall of the chamber bottom 64.

[0007] The cooling of the chamber bottom is carried out in several stages. The chamber bottom 17 is cooled by thermal pumping: the passage of air 68 through each hole 62 will locally pump energy to cool the chamber bottom 17. The air which passes through the holes 62 of the chamber bottom 17 is directed to cool the thermal protection screen 58 by air impact, which makes it possible to increase the cooling efficiency of the thermal protection screen 58 by reducing its temperature. The flow of air has the effect of cooling the upstream face 70 of the thermal protection screen 58 by forced convection. A cooling film is then generated along this upstream face 70. After impacting the thermal protection screen 58, the cooling air is discharged downstream.

[0008] However, two crack zones can form: on the chamber bottom at the level of the brazings 66 and on the thermal protection screen 58 around the injection system 22. Cracks can also appear at the level of the annular chamber bottom 17. These phenomena result from a concentration of stresses at the level of the brazings, which form crack initiation zones, and from a lack of ventilation in the attachment zone between each thermal protection screen 58 and the annular chamber bottom 17.

[0009] To limit these phenomena, document FR 2009348 describes deflectors, or thermal protection screens, each formed by two separate plates fixed independently of each other to the bottom of the combustion chamber by a stud of fixing. This arrangement eliminates the need for brazing between the chamber bottom and the protective heat shield, which simplifies the fixing of the thermal protection shields and reduces the thermal stresses applied to each of the plates. However, there is a risk of exposing the fixing stud to high temperatures, which would cause it to wear prematurely or even break.

[0010] This document aims to remedy these drawbacks. Summary of the invention

[0011] The present document proposes an annular combustion chamber for a turbomachine comprising:

[0012] -an inner annular wall and an outer annular wall;

[0013] -an annular chamber bottom comprising a plurality of first injector head passage openings;

[0014] -at least one deflector arranged downstream of the chamber bottom, said deflector comprising at least one fixing stud comprising an area fixed to said chamber bottom,

[0015] in which said fixing pad comprises an internal cooling circuit passing through at least a portion of said fixing pad and opening upstream of the annular chamber bottom.

[0016] The cooling circuit reduces the thermomechanical stresses to which the mounting stud is subjected and improves the service life of the combustion chamber. The creation of ventilation in the mounting stud improves thermal protection and reduces damage to the combustion chamber in flight.

[0017] The inner annular wall may extend inside the outer annular wall. The annular chamber bottom may connect the upstream ends of the inner annular wall and the outer annular wall.

[0018] The outer annular wall and the inner annular wall are defined relative to a longitudinal axis of the turbomachine.

[0019] The fixing stud may comprise an end which fits into a third opening provided in the chamber bottom. Said end may be engaged in the third opening of the annular chamber bottom and may be capable of receiving a clamping member for fixing said deflector to the annular chamber bottom.

[0020] Each deflector may form a heat shield. Each deflector may comprise a second opening aligned with one of the first openings of the annular chamber bottom. Each deflector may comprise two structurally distinct plates fixed independently of each other to said chamber bottom by one of said fixing studs. The plates forming each deflector may be identical. Each plate may comprise a first edge, an edge portion of the second opening, a second edge. The first edge of one of the plates may be arranged with a cold clearance j 1 opposite the first edge of the other plate. Similarly, the second edge of said plate may be arranged with a cold clearance j2 opposite the second edge of the other plate. The edge portions of the second opening of the plates may delimit the second opening of the deflector.

[0021] These games j 1 and j2 can be determined to be hot-cancelled so that the first edge and the second edge come into contact with each other in order to create a tight joint protecting the bottom of the chamber from the combustion flame. Each plate of said deflector can expand both vertically and horizontally. The clearances j 1 and j2 can be identical.

[0022] The first edge and the second edge of the first plate and / or the first edge and the second edge of the second plate may extend in a general direction included in a first plane inclined obliquely relative to a second plane comprising the longitudinal axis and passing through the center of the second opening of the thermal protection screen. The first plane may be inclined at an angle of between 30 and 60° relative to the second plane, preferably of the order of 45°.

[0023] Each plate may comprise a circumferential edge and a radial edge connected to the first and second edges of said plate, the circumferential edge and the radial edge of said plate meeting at a vertex in the vicinity of which the fixing stud is formed projecting upstream from an upstream face of said plate. Each plate may be equipped with a single fixing stud. Said fixing stud may be cylindrical for example with a circular section.

[0024] According to one embodiment, the fixing pad of one of the plates or of each plate of the deflector may comprise the cooling circuit.

[0025] The cooling circuit may comprise at least one longitudinal channel extending along a longitudinal axis of the fixing stud. The longitudinal axis of the stud may be parallel to the longitudinal axis of the combustion chamber. The longitudinal channel may comprise a first end opening upstream of the chamber bottom and a second end opposite the first end.

[0026] The longitudinal channel may be cylindrical with a circular section, and arranged in the center of the fixing pad.

[0027] For example, the second end of the longitudinal channel of the fixing pad may open downstream of the plate comprising said fixing pad. Alternatively, the second end of the longitudinal channel of the fixing pad may open upstream of the plate comprising said fixing pad, and downstream of the chamber bottom.

[0028] According to one embodiment, the cooling circuit may comprise at least one transverse channel extending along an axis forming an angle with the longitudinal axis of the fixing pad. The transverse channel may comprise a first end of opening into the longitudinal channel and a second end opening downstream of the chamber bottom.

[0029] The first end of the transverse channel may be connected to the second end of the longitudinal channel.

[0030] The second end of the transverse channel may open onto a radially external surface of the fixing stud.

[0031] The second end of the transverse channel may open onto a radially external surface of the plate comprising said fixing pad. Thus, the transverse channel may pass through a portion of said plate.

[0032] The transverse channel may extend along an axis perpendicular to the longitudinal axis of the longitudinal channel.

[0033] According to one embodiment, the cooling circuit may comprise a plurality of first transverse channels distributed circumferentially around the longitudinal channel in a first transverse plane.

[0034] The cooling circuit may comprise a plurality of second transverse channels distributed circumferentially around the longitudinal channel in a second transverse plane spaced longitudinally from the first transverse plane.

[0035] The number of first transverse channels may be different from the number of second transverse channels. For example, the first transverse channels may be formed by four transverse channels perpendicular to each other. Similarly, the second transverse channels may be formed by four transverse channels perpendicular to each other.

[0036] According to another embodiment, the first transverse channels may be formed by eight transverse channels distributed in a star shape, such that these transverse channels are circumferentially equidistant. Similarly, the second transverse channels may be formed by eight transverse channels distributed in a star shape, such that these transverse channels are circumferentially equidistant.

[0037] Of course, the first transverse channels may be formed by any other number of transverse channels distributed circumferentially around the longitudinal axis of the fixing stud equidistantly or not. Similarly, the second transverse channels may be formed by any other number of transverse channels distributed circumferentially around the longitudinal axis of the fixing stud equidistantly or not.

[0038] According to one embodiment, the deflector may comprise at least one jet flattening disc arranged downstream of the deflector and opposite an air outlet opening of the longitudinal channel and at a longitudinal distance from said air outlet of the longitudinal channel. The jet flattening disc may be configured to direct the air leaving the longitudinal channel in a radial direction, in particular relative to the longitudinal axis of the fixing stud.

[0039] According to one embodiment, the jet flattener disc can be configured to direct the air leaving the longitudinal channel along an axis forming a non-zero angle with the longitudinal axis of the fixing pad.

[0040] One or each of the plates of the deflector may comprise the flattening disc. The flattening disc may be equipped with at least one fastener extending perpendicular to the disc and mounted in a housing provided in said plate. Said fastener may be brazed to said plate.

[0041] The cooling circuit may comprise an annular channel extending longitudinally. The second end of the longitudinal channel may be connected to said annular channel, for example by one or two bent channels.

[0042] The annular channel may be formed by an annular recess in the fixing stud, such that said annular channel surrounds a radially central portion of the fixing stud, for example a solid radially central portion of said fixing stud. Thus, the cooling air flow may flow close to the radially outer surface of the fixing stud, to impact the rear face of the deflector plates.

[0043] The annular channel can open downstream of the plate comprising the fixing pad provided with said cooling circuit.

[0044] The cooling circuit may comprise a longitudinal air outlet channel connected to the annular channel and opening downstream of the plate comprising the fixing stud provided with said cooling circuit. The jet flattening disc may be arranged opposite the outlet of the longitudinal air outlet channel.

[0045] The cooling circuit may comprise a transverse channel connected to the annular channel and opening downstream of the chamber bottom. In particular, said transverse channel may pass through a portion of the plate comprising the fixing stud provided with said cooling circuit.

[0046] The combustion chamber may comprise a mixing bowl mounted in each of the first openings and connected to the chamber bottom. The mixing bowl may be mounted with a longitudinal and radial degree of freedom on the chamber bottom. More particularly, the mixing bowl may be integral with a means for mixing air with the fuel, these mixing means being formed upstream of the bowl. The degree of freedom thus formed allows differential thermal expansions between the mixing bowl and the chamber bottom.

[0047] The mixing bowl may be mounted with a radial degree of freedom in an annular groove in the chamber bottom. This annular groove may be oriented radially inwards and receive a radial annular rim of the mixing bowl.

[0048] The perimeter of each of the first openings of the chamber bottom can include openings opposite the deflector, so that air can circulate from upstream of the chamber bottom and impact the deflector plates.

[0049] The present document also relates to an aircraft turbomachine, such as an aircraft turbojet or turboprop, comprising an annular combustion chamber as mentioned above. Brief description of the figures

[0050] [Fig-1] already described, is a sectional view of a combustion chamber;

[0051] [Fig.2] is a sectional view of an air and fuel injection system;

[0052] [Fig.3] is a front view of a deflector according to the present document;

[0053] [Fig.4] represents a longitudinal sectional view and a view of a section of a first example of a deflector according to this document;

[0054] [Fig.5] represents a longitudinal sectional view and a view of a section of a second example of a deflector according to this document;

[0055] [Fig.6] represents a longitudinal sectional view and a view of a section of a third example of a deflector according to this document;

[0056] [Fig.7] represents a longitudinal sectional view and a view of a section of a fourth example of a deflector according to this document;

[0057] [Fig.8] represents a longitudinal sectional view and a partial front view of the third example of a deflector equipped with a jet flattening disc;

[0058] [Fig.9] represents a longitudinal sectional view and a partial front view of the fourth example of a deflector equipped with a jet flattening disc;

[0059] [Fig. 10] represents a side view and a perspective view of the jet flattening disc equipping the deflector of [Fig.8] or [Fig.9].

[0060] [Fig. 11] represents a longitudinal sectional view and a view of a section of a fifth example of a deflector according to the present document;

[0061] [Fig. 12] represents a longitudinal sectional view and a view of a section of a sixth example of a deflector according to the present document;

[0062] [Fig. 13] represents a longitudinal sectional view and a view of a section of the sixth example of deflector equipped with a jet flattening disc of [Fig. 10]. Detailed description of the invention

[0063] [Fig. 3] shows a deflector 100 which can for example be fixed to the chamber bottom 17 of the combustion chamber of [Fig. 2]. The deflector 100 forms a heat shield and comprises two plates 102i and 1022 which are distinct and independent of each other. Each plate 102i and 1022 is provided with a fixing stud 106i and 106 2, respectively, which extends from an upstream face of said plate 102. The plates 102i and 1022 are configured to form an opening 110 of the deflector 100. The opening 110 is arranged opposite one of the first openings 20 of the bottom of room 17.

[0064] Each plate 102b 1022 comprises a circumferential edge PCi, PC2 and a radial edge PRb PR2 meeting at a vertex Sb S2 in the vicinity of which the fixing stud 106 is formed. As shown in the figures, each plate 102 is equipped with a single cylindrical fixing stud 106 with a circular section. Alternatively, each plate 102 can be equipped with several fixing studs 106. The fixing stud 106 can further have a square, rectangular, hexagonal, etc. section.

[0065] To limit thermomechanical constraints, one or each of the fixing pads 106i and 1062 comprises a cooling circuit configured to circulate air extracted from outside the combustion chamber in at least a portion of the fixing pad 106.

[0066] [Fig. 4] shows a first example of embodiment of the cooling circuit 112 according to a sectional view. The fixing stud 106 comprises an end inserted into an orifice provided in the chamber bottom 17 and tightened by a nut 114 against the chamber bottom 17. The end of the fixing stud 106 has a section smaller than the rest of the section of the fixing stud 106, so as to form a shoulder 107 which abuts against the chamber bottom 17. Each fixing stud 106 may have a circular section.

[0067] The cooling circuit 112 comprises a longitudinal channel 116 comprising a first end 118 opening upstream of the chamber bottom 17. The longitudinal channel 116 is formed by a recess radially in the center of the fixing stud 106. The cooling circuit 112 further comprises four transverse channels 120 comprising one end opening into the longitudinal channel 116 and another end 122 opening onto a radially external surface 123 of the fixing stud 106. Each transverse channel 120 extends radially. The transverse channels 120 are distributed circumferentially at equal distances around the fixing stud 106. The ends 122 of the transverse channels 120 open downstream of the chamber bottom 17 and upstream of the plate 102.

[0068] The cooling circuit 112 is supplied with air from outside the chamber bottom 17 and passes through the fixing stud 106, which allows it to be cooled. The air leaving the transverse channels 120 can be reused to form a cooling film generated along the upstream face 101 of the plate 102 by the air introduced through the holes 62.

[0069] [Fig. 5] shows a second exemplary embodiment of the cooling circuit 212, which comprises the same elements as the first exemplary embodiment of the cooling circuit 112. In contrast, the cooling circuit 212 comprises first transverse channels 120i arranged in a first transverse plane PI and second transverse channels 1202 arranged in a second plane transverse P2 spaced longitudinally from the first transverse plane PI.

[0070] The first transverse channels 120i comprise eight transverse channels 120i arranged in a star shape around the fixing pad 106. In the same way, the second transverse channels 1202 comprise eight transverse channels 120i arranged in a star shape around the fixing pad 106.

[0071] [Fig. 6] shows a second embodiment of the cooling circuit 312, which comprises the same elements as the first embodiment of the cooling circuit 112. Unlike this, the cooling circuit 312 does not comprise transverse channels. The longitudinal channel 116 has a second end 119 opening onto the downstream face 103 of the plate 102. Thus, the longitudinal channel 116 passes completely through the fixing stud 106, which is hollow in this case. The air leaving the cooling circuit 312 can be used for combustion in the combustion chamber. This makes it possible to improve the performance of the combustion chamber in terms of ignition, flame attachment, etc.

[0072] [Fig. 7] shows another alternative embodiment of the cooling circuit. The cooling circuit 412 comprises the same elements as the cooling circuit 312 of [Fig. 6]. In addition, the cooling circuit 412 comprises first transverse channels 120i and second transverse channels 1202, similar to those of the cooling circuit 212 of [Fig. 5]. The transverse channels 120 make it possible to uniform the cooling along the fixing pad 106.

[0073] [Fig. 8] shows another alternative embodiment of the deflector 100 which comprises the cooling circuit 312 of [Fig. 6]. In addition, the plate 102 of the deflector 100 comprises a jet flattener disc 124 arranged opposite the second end 119 of the longitudinal channel 116. The jet flattener disc 124, which will be described in more detail in relation to [Fig. 10], is configured to redirect the air flow F1 passing through the longitudinal channel 116 in a radial flow direction F2 at the outlet of the second end 119.

[0074] [Fig. 9] shows another alternative embodiment of the deflector 100 which comprises the cooling circuit 412 of [Fig. 7]. In addition, the plate 102 of the deflector 100 comprises a jet flattening disc 124 arranged opposite the second end 119 of the longitudinal channel 116. The jet flattening disc 124, which will be described in more detail in relation to [Fig. 10], is configured to redirect the air flow F1 passing through the longitudinal channel 116 in a radial flow direction F2 at the outlet of the second end 119. The radial flow F2 makes it possible to cool the downstream face 103 of the plate 102.

[0075] The jet flattening disc 124 is formed by a circular plate having a surface greater than the surface of the second end 119 or the section of the longitudinal channel 116, so that the jet flattening disc 124 completely covers the second end 119. Preferably, the jet flattener disc 124 is provided with two fasteners 126 which fit into housings provided in the upstream face 103 of the plate 102. The fasteners 126 extend longitudinally so that the jet flattener disc 124 is spaced longitudinally from the second end 119 to allow air to escape from the second end 119. The fasteners 126 may be brazed to the plate 102.

[0076] [Fig. 11] shows another example of the cooling circuit similar to the cooling circuit 112 of [Fig. 4]. The cooling circuit 512 comprises an annular channel 130 surrounding a solid central portion 132 of the fixing stud 106. The annular channel 130 comprises a first end 131 opening into the longitudinal channel and two opposite second ends opening into a transverse channel 134. The transverse channel 134 is arranged in the plate 102 and opens at one end 138 at a radially external surface of said plate 102. The cooling circuit 512 thus makes it possible to cool the plate 102.

[0077] [Fig. 12] shows an example of the cooling circuit 612 comprising the same elements as the cooling circuit 512. Unlike, the annular channel 130 opens into a downstream longitudinal channel 140 passing through the plate 102 and opening onto the downstream face 103 of the plate 102.

[0078] [Fig. 13] shows another alternative embodiment of the deflector 100 which comprises the cooling circuit 612 of [Fig. 12]. The deflector 100 further comprises the jet flattening disc 124 of [Fig. 10] arranged opposite the air outlet of the downstream longitudinal channel 140.

Claims

Claims

1. An annular combustion chamber of a turbomachine comprising: - an inner annular wall (14) and an outer annular wall (16); - an annular chamber bottom (17) comprising a plurality of first openings (20) for the passage of injector heads; - at least one deflector (100) arranged downstream of the chamber bottom (17), said deflector comprising at least one fixing stud (106) comprising a zone fixed to said chamber bottom, in which said fixing stud (106) comprises an internal cooling circuit (112, 212, 312, 412, 512, 612) passing through at least a portion of said fixing stud (106) and opening upstream of the annular chamber bottom (17), in which each deflector (100) comprises a second opening (110) aligned with one of the first openings (20) of the annular chamber bottom (17),and wherein each deflector comprises two structurally distinct plates (102) fixed independently of each other to said chamber bottom (17) by one of said fixing studs (106), wherein each plate comprises a first edge, an edge portion of the second opening and a second edge, the first edge of one of the plates being arranged with a cold clearance opposite the first edge of the other plate and the second edge of said plate being arranged with a cold clearance opposite the second edge of the other plate, the edge portions of the second opening of the plates delimiting the second opening of the deflector.,

2. Chamber according to claim 1, in which the cooling circuit (112,212,312,412,512,612) comprises at least one longitudinal channel (116,140) extending along a longitudinal axis of the fixing stud (106), said longitudinal channel comprising a first end (118) opening upstream of the chamber bottom (17) and a second end opposite the first end.

3. Chamber according to claim 2, in which the second end of the longitudinal channel (116,140) of the fixing stud (106) opens downstream of the plate (102) comprising said fixing stud (106).

4. Chamber according to one of the preceding claims taken in combination with claim 2, in which the cooling circuit (112,212,412,512) comprises at least one transverse channel (120) extending along an axis forming an angle with the longitudinal axis of the fixing stud (106), the transverse channel (120) comprising a first end opening into the longitudinal channel (116) and a second end opening downstream of the chamber bottom (17).

5. Chamber according to claim 4, in which the second end of the transverse channel (120) opens onto a radially external surface of the fixing stud (106) or onto a radially external surface of the plate (102) comprising said fixing stud (106).

6. Chamber according to one of claims 4 or 5, in which the cooling circuit (212, 412) comprises a plurality of first transverse channels (1200 distributed circumferentially around the longitudinal channel in a first transverse plane (PI) and a plurality of second transverse channels (1202) distributed circumferentially around the longitudinal channel in a second transverse plane (P2) spaced longitudinally from the first transverse plane.

7. Chamber according to one of the preceding claims taken in combination with claim 2, wherein the deflector (100) comprises at least one jet flattening disc (124) arranged downstream of the deflector (100) and arranged opposite an air outlet opening of the longitudinal channel (116, 140) and at a longitudinal distance from said air outlet of the longitudinal channel, the jet flattening disc (124) being configured to direct the air leaving the longitudinal channel in a radial direction.

8. Chamber according to one of the preceding claims taken in combination with claim 2, in which the cooling circuit (512,612) comprises an annular channel (130) extending longitudinally, the second end of the longitudinal channel (116) being connected to said annular channel (130).

9. Turbomachine, such as an aircraft turbojet or turboprop, comprising an annular combustion chamber according to one of the preceding claims.

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