Cooling air distribution box

Abstract

This document relates to a cooling air distribution housing (2) extending about an axis (X) and comprising a first wall (8), radially internal to the axis (X), intended to be arranged radially opposite a turbomachine housing (24), characterized in that it comprises at least means (22) for attaching the first wall (8) to the housing (24), said means (22) being arranged in a central portion (26) of the first wall (8). Abstract figure: Figure 2

Description

Title of the invention: Cooling air distribution box Technical field

[0001] The present disclosure relates to the field of maintaining a cooling air distribution housing on a low pressure turbine casing of a turbomachine. More specifically, the present document relates to means for fixing said distribution housing. Prior art

[0002] There are different methods for maintaining a cooling air distribution box on an external casing of a turbomachine. As illustrated in [Fig.l], it is known to produce a cooling air distribution box 2 having a hook at an upstream clamping zone 4 and a downstream clamping zone 6 of an external casing.

[0003] However, in such a configuration, the distribution housing is positioned at too great a radial distance from the turbine casing and does not allow sufficient differential expansion of the distribution housing relative to the external casing.

[0004] The distribution box is at the temperature of the air circulating inside while the external casing is hotter. This means that the part on which the distribution box is clamped upstream and downstream expands considerably. Stresses are then exerted on the distribution box and on elements supporting this distribution box. Cracks can appear at the upstream and downstream fixings. Summary

[0005] The present disclosure improves the situation.

[0006] The present document relates to a cooling air distribution housing extending around an axis and comprising a first wall, radially internal with respect to the axis, intended to be arranged radially opposite a turbomachine casing, characterized in that it comprises at least means for fixing the first wall to the casing, said fixing means being arranged in a central portion of the first wall.

[0007] The fixing means allow isostatic maintenance of the distribution housing relative to a support to which the housing is fixed. In particular, the support may be an external casing of a turbomachine. These fixing means also allow free expansion avoiding the formation of cracks at the level of the fixings as in the prior art.

[0008] Good mechanical strength of the distribution box is obtained under the loads to which it is subjected. A stiffness of the connection between the distribution box The distribution box and the external casing are maximized. The forces during limit and ultimate accelerations on the distribution box and the external casing are minimized. The casing on which the distribution box is fixed can expand freely. Vibration of the distribution box is prevented during use and differential expansions of the parts between them are permitted. The fixing means make it possible to minimize a radial distance between the air supply ducts and the external casing improving the efficiency of the system comprising the distribution box and the air supply ducts.

[0009] The fixing means may be removable fixing means.

[0010] These removable fixing means allow isostatic maintenance of the housing of distribution. The fixing means can be removed.

[0011] Said fixing means may be arranged in the vicinity of the radial projection of the center of gravity of the distribution box on the first wall of the distribution box.

[0012] Greater stability and support of the distribution box are obtained thanks to the positioning of the fixing means.

[0013] Said fixing means may be arranged inside a closed surface delimited by a projection of a circle of radius R on the first wall, centered on the projection of the center of gravity on the first wall, the radius R being between 10mm and 100mm.

[0014] Said fixing means may be arranged longitudinally substantially in the middle of the longitudinal extent of the first wall.

[0015] Said fixing means may form the sole fixing of said distribution box to the casing.

[0016] Said fixing means may comprise at least two separate fixing members of the distribution box to the casing.

[0017] The distribution box may comprise a second wall, radially external with respect to the axis, the second wall being arranged radially opposite the first wall, said second wall comprising an access opening to the means for fixing the first wall and a removable member for closing said access opening.

[0018] This access opening provides a simple and inexpensive means for correctly positioning the fixing means.

[0019] The access opening may comprise a tubular passage.

[0020] The tubular passage may be formed so as to project from an external face of the external wall of the distribution housing.

[0021] The housing may comprise a boss on which the first wall of the distribution housing is mounted, said fixing means fixing the first wall to said boss.

[0022] This boss makes it easier to position said fixing means. This boss also makes it possible to generate a clearance between said external casing and the distribution box.

[0023] The fixing means may comprise at least one screw intended to be screwed to the casing.

[0024] The present document relates to a turbine, such as a low pressure turbine of a turbomachine, comprising a distribution box of the aforementioned type.

[0025] The present document relates to a turbomachine comprising a turbine of the aforementioned type.

[0026] Brief description of the drawings

[0027] Other characteristics, details and advantages will appear on reading the detailed description below, and on analyzing the attached drawings, in which: Fig.l

[0028] [Fig.l] shows a cooling air distribution box according to the prior art. Fig. 2

[0029] [Fig.2] shows a three-dimensional section of an air distribution box of re cooling along a circumferential wall, according to a first embodiment. Fig. 3

[0030] [Fig.3] shows a three-dimensional section of an air distribution box of re cooling without a removable sealing member along a circumferential wall, according to a first embodiment. Fig. 4

[0031] [Fig.4] shows a three-dimensional top view of an air distribution box cooling, according to a first embodiment. Fig. 5

[0032] [Fig.5] shows a longitudinal three-dimensional section passing through an opening access to a cooling air distribution box, according to a first embodiment. Fig. 6

[0033] [Fig.6] shows a top view of a fixing member, according to a first mode of realization. Fig. 7

[0034] [Fig.7] shows a three-dimensional section of an air distribution box of re cooling along a circumferential wall, according to a second embodiment Fig. 8

[0035] [Fig.8] shows a three-dimensional section of an air distribution box of re cooling without a removable sealing member according to a circumferential wall, according to a second embodiment. Description of the embodiments

[0036] The present document relates to a turbine, such as a low-pressure turbine of a turbomachine, extending around a longitudinal X axis and comprising an outer casing supporting a cooling air distribution housing. The cooling air distribution housing extends around said X axis.

[0037] As illustrated in Figures 2 to 6, 7 and 8, the distribution housing 2 comprises a radially internal wall 8, also called the first wall, a radially external wall 10, also called the second wall, connected to the radially internal wall 8 by an upstream connecting wall 12 and a downstream connecting wall 14 curved convexly and two circumferential walls 16, 18 which together define the distribution housing 2. The circumferential walls 16, 18 comprise a plurality of air supply ducts 20.

[0038] As illustrated in Figures 2 to 6, 7 and 8, the distribution box 2 comprises removable fixing means 22 arranged directly between the radially internal wall 8 and the external casing 24. By fixing means 22 of the distribution box 2, we mean fixing means 22 which provide a direct connection between said radially internal wall 8 and the external casing 24. By removable fixing means 22, we mean a fixing which does not make any movement once positioned and which can be removed. Once positioned, these removable fixing means 22 prevent any movement in the three directions of space. Said removable fixing means 22 are arranged in a central portion 26 of the radially internal wall 8 of the distribution box 2. By central portion 26 is meant a portion centered relative to a first end 28 and a second end 30 of the radially internal wall 8 of the distribution box 2.The fixing means 22 are arranged inside a closed surface delimited by a projection of a circle 32 of radius R onto the radially internal wall 8, centered on the projection of the center of gravity onto the radially internal wall 8 of the distribution box 2. The radius R is between 1 and 10 cm, for example 5 cm in the presence of a single fixing member 42. The circle 32 of radius R is a circle having an axis perpendicular to the plane of the disc formed by the circle 32, this axis being a radial axis. The fixing means 22 are arranged substantially in the middle of the longitudinal extent of the radially internal wall 8 of the distribution box 2.

[0039] The distribution box 2 comprises an access opening 34 on its radially external wall 10 configured for the installation of the fixing means 22 by a removable closure member 36 and the disassembly of this same removable member. closure 36. The access opening 34 comprises a tubular passage 38. This tubular passage 38 is formed so as to project from an external face 40 of the radially external wall 10.

[0040] The removable closure member 36 can be removed, leaving free passage for the fixing means 22 and for a tightening tool configured to tighten said fixing means 22 on the central portion 26 of the radially internal wall 8 of the distribution housing 2. The tightening tool is then removed and the removable closure member 36 is replaced. A system for closing the access opening 34 by the removable closure member 36 is configured to seal the distribution housing 2.

[0041] Said fixing means 22 form the only point of fixing of the distribution box 2 to the external casing 24.

[0042] In a particular embodiment of the invention, the fixing means 22 comprise at least one fixing member 42 passing through the radially internal wall 8 of the distribution housing 2 and the external casing 24. More particularly, the fixing means 22 comprise a single fixing member 42. An orifice is made on the radially internal wall 8 radially opposite the external casing 24. By radially internal wall 8 radially opposite the external casing 24, is meant a radially internal wall 8 which extends at a short distance of between 1 and 5 cm or less than 1 cm from said external casing 24. This orifice is configured to accommodate the fixing member 42 which is assembled on a boss 44 projecting from the external casing 24. The boss 44 comprises a crimped or keyed sleeve. This configuration results in a clearance between the distribution box and the external casing.

[0043] As illustrated in [Fig.6], the fixing member 42 may be a screw 46 screwed into the external casing 24.

[0044] In the embodiment illustrated in Figures 7 and 8, the fixing means 22 may comprise a plurality of fixing members 42. In the present embodiment, three fixing members 42 are arranged in the central portion 26 of the distribution box 2. The three fixing members 42 are arranged inside the closed surface delimited by the projection of the circle 32 of radius R on the radially internal wall, centered on the projection of the center of gravity on the radially internal wall of the distribution box. In the present embodiment. The radius R is between 1 and 10 cm. Three orifices are made on the radially internal wall 8 in radial facing relation with the external casing 24, inside the closed surface delimited by the projection of the circle of radius R. These three orifices are configured to each accommodate a fixing member 42 which is assembled on a boss 44 projecting from the external casing.Boss 44 has a socket crimped or keyed by orifice.

[0045] The fixing means 22 allow isostatic maintenance of the distribution box 2 relative to the external casing 24. These fixing means 22 also allow free expansion avoiding the formation of cracks at the level of the fixings as in the prior art.

[0046] Good mechanical strength of the distribution box 2 is obtained under the loads to which it is subjected. A stiffness of the connection between the distribution box 2 and the external casing 24 is maximized. The forces during limit and ultimate accelerations on the distribution box 2 and the external casing 24 are minimized. The external casing 24 on which the distribution box 2 is fixed can expand freely. Vibration of the distribution box 2 is prevented during use and differential expansions of the parts between them are permitted. The fixing means 22 make it possible to minimize a radial distance between the air supply ducts 20 and the external casing 24, improving the efficiency of the system comprising the distribution box and the air supply ducts 20.

Claims

Claims

1. Cooling air distribution housing (2) extending around an axis (X) and comprising a first wall (8), radially internal with respect to the axis (X), intended to be arranged radially opposite a turbomachine casing (24), characterized in that it comprises at least means (22) for fixing the first wall (8) to the casing (24), said fixing means (22) being arranged in a central portion (26) of the first wall (8) in the vicinity of the radial projection of the center of gravity of the distribution housing (2) on the first wall (8) of the distribution housing (2).

2. Distribution box (2) according to claim 1, in which the fixing means (22) are removable fixing means (22).

3. Distribution box (2) according to claim 2, wherein said fixing means (22) are arranged inside a closed surface delimited by a projection of a circle of radius R on the first wall, centered on the projection of the center of gravity on the first wall, the radius R being between 10mm and 100mm.

4. Distribution box (2) according to one of claims 1 to 3, wherein said fixing means (22) are arranged longitudinally substantially in the middle of the longitudinal extent of the first wall (8).

5. Distribution box (2) according to one of the preceding claims, in which said fixing means (22) form the only fixing of said distribution box (2) to the casing (24).

6. Distribution box (2) according to one of the preceding claims, in which said fixing means (22) comprise at least two fixing members (42) distinct from the distribution box (2) to the casing (24).

7. Distribution box (2) according to one of the preceding claims, in which the distribution box (2) comprises a second wall (10), radially external with respect to the axis (X), the second wall (10) being arranged radially opposite the first wall (8), said second wall (10) comprising an access opening (34) to the fixing means (22) of the first wall (8) and a removable closing member (36) of said access opening (34).

8. Distribution box according to one of the preceding claims, in which the casing (24) comprises a boss (44) on which the first wall (8) of the distribution box (2), said fixing means (22) fixing the first wall (8) to said boss (44).

9. Distribution box according to one of the preceding claims, in which the fixing means (22) comprise at least one screw (46) intended to be screwed to the casing (24).

10. Turbine, such as a low pressure turbine of a turbomachine, comprising a distribution housing according to one of the preceding claims.

11. Turbomachine comprising a turbine according to the preceding claim.

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