Device for securing a cooling tube to a turbine engine casing

Abstract

The present disclosure relates to a device for securing an air-jet cooling tube to a turbine engine casing, the device comprising: - an external support designed to be arranged around a turbine engine casing, - a collar designed to surround a tube and fasten it to the support, and - a graphite ring intended to be positioned around the tube, between the collar and the tube, the ring comprising three ring portions each intended to surround a portion of the tube, the ring surrounding an angular portion of between 240° inclusive and 300° inclusive of the circumference of the tube.

Description

[0001] Device for securing a cooling tube to a turbomachine housing

[0002] TECHNICAL FIELD

[0003] This presentation is generally concerned with the aeronautical field and more specifically with the field of turbomachinery.

[0004] More specifically, this presentation concerns a device for holding one (or more) cooling tube(s) on a turbomachine housing.

[0005] STATE OF THE ART

[0006] A turbofan engine typically comprises a primary and a secondary flow through which air flows. The primary flow passes successively through one (or more) compressor(s), a combustion chamber, and one (or more) turbine(s). The turbine consists of stages of distributors (fixed blades) attached to a turbine housing.

[0007] The airflow circulating in the primary duct through the turbine is at a high temperature and induces heating of the turbine casing. This heating of the turbine casing can create thermal expansion which tends to increase the functional clearances between the turbine blade tips and the turbine casing, potentially degrading the turbomachine's performance.

[0008] Thus, in order to protect the turbine casing from excessive heating that would cause an unfavorable increase in operating clearances, and to ensure proper turbine performance, the turbomachine includes a cooling system comprising several perforated tubes or ramps arranged around the external surface of the turbine casing. These ramps are supplied with pressurized air from the secondary flow. Such a cooling system is known as LPTACC (Low Pressure Turbine Active Clearance Control).

[0009] The cooling tubes must be fixed around the turbine housing.

[0010] One problem is that the tubes must be held in position around the turbine housing in such a way as to withstand the vibrations and high temperatures induced by the operation of the turbomachine. GENERAL OVERVIEW

[0011] One aim of this presentation is to propose a device for securing a cooling tube to a housing, ensuring the tube remains in good condition and is reliably positioned. To this end, one aspect of this presentation describes a device for securing an air-jet cooling tube to a turbomachine housing; the device comprises:

[0012] - an external bracket suitable for placement around a turbomachine housing, - a collar suitable for encircling a tube and attaching it to the bracket, and

[0013] - A graphite ring designed to be positioned around the tube, between the collar and the tube. The ring comprises three sections, each designed to encircle a portion of the tube, with the ring encircling a section between 240° and 300° of the tube. The use of a graphite ring protects both the tube and the collar from wear. This is particularly advantageous when both the tube and the collar are metallic. Furthermore, the three-section design facilitates positioning and replacement, ensures good isostaticity, and allows for precise positioning of the ring around the collar, thus maintaining good concentricity between the tube and the collar.

[0014] Advantageously, but optionally:

[0015] - the ring has an annular shape comprising an outer wall, the outer wall includes a first annular rim, a second annular rim and an annular channel between the first rim and the second rim, the outer wall forming an annular recess suitable for housing the collar;

[0016] - the first rim and the second rim include a radius of a dimension greater than the sum of a radius of the channel and a thickness of the collar;

[0017] - each ring segment has a central angle between 60° and 100°;

[0018] - the collar includes lugs for positioning each ring portion on the collar around the tube;

[0019] - one of the lugs is positioned on the collar facing the support and between one of the ring portions and a fixing of the collar to the support;

[0020] - the collar is metallic;

[0021] - The device includes several clamps and rings designed to hold the tube onto the support. According to another aspect of this presentation, an air jet cooling system for a turbomachine housing is proposed, the system comprising:

[0022] - a cooling tube with holes adapted for injecting air onto a crankcase,

[0023] - a tube retaining device around the housing as previously described, in which the collar is positioned around the tube and is fixed to the support, and the graphite ring is positioned around the tube, between the collar and the tube, the ring comprising three ring portions intended to each surround a portion of the tube, the ring surrounding an angular portion between 240° inclusive and 300° inclusive of the circumference of the tube.

[0024] According to another aspect of this presentation, a turbomachine assembly is proposed, comprising a turbomachine housing, and a cooling system as previously described.

[0025] According to another aspect of this presentation, a turbomachine for an aircraft is proposed, comprising a turbomachine assembly as previously described.

[0026] According to another aspect of this presentation, an aircraft is proposed comprising a fuselage and a turbomachine as previously described, in which the turbomachine is fixed to the fuselage.

[0027] DESCRIPTION OF THE FIGURES

[0028] Other features, purposes, and advantages will become apparent from the following description, which is purely illustrative and not exhaustive, and should be read in conjunction with the attached drawings on which:

[0029] Figure 1 illustrates an aircraft schematically.

[0030] Figure 2 illustrates a schematic cross-sectional view of an aircraft propulsion system. Figure 3 illustrates a perspective cross-sectional view of part of a turbomachine assembly, according to one possible embodiment of the present presentation.

[0031] Figure 4 illustrates a perspective view of a portion of the cooling system, according to one possible embodiment of the present presentation.

[0032] Figure 5 illustrates a cross-sectional view of a portion of the cooling system, according to one possible embodiment of the present presentation.

[0033] Figure 6 illustrates a perspective view of a support device according to one possible embodiment of the present presentation. Throughout the figures, similar elements bear identical references.

[0034] DETAILED DESCRIPTION

[0035] Aircraft

[0036] An aircraft 100 is a device configured to rise and move through the air, and can, for example, be an airplane, as illustrated in Figure 1, civil or military, or even a helicopter. An aircraft 100 comprises an airframe which, in the case of an airplane, consists of a fuselage, wings, tail assembly, control surfaces, and landing gear.

[0037] Propulsion system

[0038] A propulsion unit 1 comprises an engine 2 (or turbomachine) and optionally a nacelle 3, as illustrated in Figure 2, and has a principal direction extending along a longitudinal axis XX. The propulsion unit 1 is configured to be fixed to the airframe of the aircraft 100, for example, under its wings in the case of an airplane, by means of a pylon (or mast). The propulsion unit 1 may also be mounted on the wing of the airplane or at the rear of its fuselage, or even integrated into its fuselage. The engine 2 may be a ducted, twin-spool, turbofan engine with direct drive, as described below, but may also have a different number of cylinders and / or strokes, and / or be another type of turbofan engine, such as a geared turbofan or a turboprop, with or without afterburner, ducted or unducted.Unless otherwise specified, the terms "upstream" and "downstream" refer to the overall direction of airflow through the propulsion unit 1 in operation. Similarly, an axial direction corresponds to the direction of the longitudinal axis XX, and a radial direction is a direction perpendicular to the longitudinal axis XX and intersecting it. Furthermore, an axial plane is a plane containing the longitudinal axis XX, and a radial plane is a plane perpendicular to the longitudinal axis XX. A circumference is defined as a circle lying on a radial plane and whose center lies on the longitudinal axis XX. A tangential or circumferential direction is a direction tangent to a circumference: it is perpendicular to the longitudinal axis XX but does not pass through it.Finally, the adjectives "interior" (or "internal") and "exterior" (or "external") are used with reference to a radial direction so that the inner part of an element is, following a radial direction, closer to the longitudinal axis XX than the outer part of the same element.

[0039] The engine 2 comprises, from upstream to downstream, a blower 20, an engine casing 21, a compressor section 22, comprising a low pressure compressor 220 and a high pressure compressor 221, a combustion chamber 23, a turbine section 24, comprising a high pressure turbine 240 and a low pressure turbine 241.

[0040] The compressor section 22 comprises a series of stages, each including a rotating impeller (rotor) in front of a stationary impeller (stator). The turbine section 24 also comprises a series of stages, each including a stationary impeller (stator) behind which a rotating impeller (rotor) is located.

[0041] The blower 20, the rotor section of the low-pressure compressor 220, and the rotor section of the low-pressure turbine 241 are connected by a low-pressure shaft 27 extending along the longitudinal axis XX, thus forming a low-pressure housing. The rotor section of the high-pressure compressor 221 and the rotor section of the high-pressure turbine 240 are connected by a high-pressure shaft 28 extending along the longitudinal axis XX, thus forming a high-pressure housing. The low-pressure shaft 27 is generally housed, along a portion of its length, within the high-pressure shaft 28 and is coaxial with the high-pressure shaft 28.

[0042] The compressor section 22, the combustion chamber 23 and the turbine section 24 are surrounded by the engine casing 21.

[0043] The engine casing 21 defines a primary flow A within which the rotor and stator sections of the low-pressure compressor 220, the high-pressure compressor 221, the low-pressure turbine 241, and the high-pressure turbine 240 extend. The primary flow A passes completely through the engine casing 21. The stator sections within the primary flow A can thus form OGVs (Outlet Guide Vanes). In this way, the airflow circulating in the primary flow A is deflected by the rotating rotor sections and straightened by the stator sections, which are fixed relative to the engine casing 21 defining the primary flow A.

[0044] The longitudinal axis XX defines the axis of rotation for the blower 20, the rotor parts of the compressor section 22 and the rotor parts of the turbine section 24, in other words for the low pressure body and the high pressure body which are each capable of being driven in rotation around the longitudinal axis XX relative to the engine casing 21.

[0045] The stator parts of the high-pressure turbine 240 are connected to a high-pressure casing 25 and the stator parts of the low-pressure turbine 241 are connected to a low-pressure casing 26. The low-pressure turbine casing 26 delimits the primary stream A through the low-pressure turbine 241.

[0046] In the embodiment of a shrouded engine, the nacelle 3 extends radially outside the engine 2, all around the longitudinal axis XX, so as to surround both the engine casing 21, and to define a secondary channel B with the engine casing 21. The upstream part of the nacelle 3 further defines an airflow inlet through which the fan 20 draws in the airflow circulating through the propulsion assembly 1. The nacelle 3 is attached and fixed to the aircraft 100 by means of the mast.

[0047] During operation, the fan 20 draws in an airflow, a portion of which, circulating within a primary channel A that passes completely through the engine casing 21, is successively compressed within the compressor section 22, ignited within the combustion chamber 23 by fuel combustion, and expanded within the turbine section 24 before being ejected from the engine 2. Another portion of the airflow can circulate within the secondary channel B, which takes an elongated annular shape surrounding the engine casing 21. In this way, the propulsion unit 1 generates thrust. This thrust can, for example, be used to power the aircraft 100 to which the propulsion unit 1 is mounted.

[0048]

[0049] The engine 2 preferably includes a cooling system 4. The cooling system 4 is arranged around the low-pressure turbine housing 26 and radially external to the low-pressure turbine housing 26, as illustrated for example by Figure 3.

[0050] The low-pressure turbine housing 26, hereafter simply called the housing, comprises an inner surface 261, delimiting the primary flow A, and an outer surface 262. The inner surface 261 and the outer surface 262 extend around the longitudinal axis XX, the outer surface 262 being positioned radially external to the inner surface 261. Preferably, the cooling system 4 is positioned around the housing 26 and is fixed to the outer surface 262 of the housing 26.

[0051] The cooling system 4 is intended to cool the housing 26. Preferably, the cooling system 4 allows air to be injected onto the external surface 262 of the housing 26. The air injected onto the external surface 262 of the housing 26 by the cooling system 4 is advantageously extracted from the secondary flow B and fed into the cooling system 4 via a supply channel. The cooling system 4 comprises a tube 41, and preferably several tubes 41, and a retaining device 42 for the tube(s) 41, described in more detail below. Advantageously, the cooling system 4 may include several retaining devices 42. The retaining devices 42 may be positioned all around the external surface 262 and at regular intervals. Each retaining device 42 may hold one or more tubes 41.Preferably, all the retaining devices 42 forming the same concentric alignment around the external surface 262 retain the same tubes 41.

[0052] The tubes 41 are positioned side-by-side longitudinally around the housing 26. Each tube 41 of the cooling system 4 is preferably annular and extends around the longitudinal axis XX. The tube 41 may completely or partially encircle the housing 26. The tube 41 is connected to the supply channel. The tube 41 includes a plurality of holes configured to project air towards the external surface 262 of the housing 26.

[0053] The holes are preferably made in the tube 41 in a radially internal manner within the tube 41 and are advantageously aligned along the entire length of the tube 41.

[0054] Restraining device

[0055] The retaining device 42 allows the tubes 41 to be positioned around the housing 26. The retaining device 42 comprises an external support 43, a collar 44, and preferably several collars 44, and a ring 45, preferably one ring 45 for each collar, as illustrated for example by figure 4. The collar 44 is configured to fix the tube 41 to the support 43 and the ring 45 is configured to protect the tube 41 from the collar 44.

[0056] The assembly of a housing, tubes 41 (or rails), and tube supports 43, clamps 44, and rings 45 constitutes a unit called an equipped rail. The external support 43 is positioned around the housing 26 and preferably attached to the housing 26 by means of a bracket 431. The bracket 431 can be screwed to the housing 262, and the rail is screwed to the bracket 431. The support 43 advantageously allows for the positioning of several tubes 41 around the housing 26. The tubes 41 are positioned between the support 43 and the external surface 262 of the housing 26. The support 43 is configured to position the tubes 41 as close as possible to the housing 26 to improve cooling.

[0057] The support 43 is preferably made of metal to withstand the high temperatures associated with the operation of the motor 2. The collar 44 allows a tube 41 to be attached to the support 43. Each tube 41 is preferably fixed to the support 43 by several collars 44. The collar 44 surrounds the tube 41, in other words, the collar 44 surrounds a section of the tube 41 in an axial plane.

[0058] The collar 44 is fixed to the support 43. Advantageously, the collar 44 is screwed to the support 43 by a screw.

[0059] The collar 44 is preferably a wound metal band. The collar 44 extends from the support 43, encircles the tube 41, and rejoins the support 43. Advantageously, the collar 44 comprises a first end and a second end, the first and second ends being screwed onto each other on the support 43. The collar 44 has a thickness of between 0.9 and 1.1 mm and a curvilinear length of between 60 and 100 mm, and preferably 80 mm.

[0060] Preferably, each tube 41 is fixed to the support 43 by several clamps 44, and advantageously between one and three clamps 44. The clamps 44 securing each tube 41 to the support 43 are preferably evenly distributed along the tube 41. Advantageously, the support 43 may comprise several sections arranged around the housing. Each tube 41 is fixed to each section of the support 43 by a clamp 44. Furthermore, each section of the support 43 may support several tubes 41, each fixed to the section by a clamp 44.

[0061] The graphite ring 45 is designed to be positioned between each collar 44 and the tube 41. The graphite ring 45 surrounds the tube 41; in other words, the ring 45 surrounds a section of the tube 41 in an axial plane. Thus, the collar 44 is not in contact with the tube 41 but is in contact with the ring 45, and the ring 45 is in contact with the tube 41. The ring 45 has an annular shape and comprises an outer wall 47 and an inner wall 46, as illustrated, for example, in Figure 5. The inner wall 46 is preferably cylindrical and is in contact with the tube 41.

[0062] The outer wall 47 of the ring 45 preferentially comprises, along its circumference, a first annular rim 471, a second annular rim 472 and an annular channel 473 between the first rim 471 and the second rim 472. In other words, in a tangential direction the outer wall 47 of the ring 45 comprises, in this order, the first annular rim 471, the annular channel 473 and the second annular rim 472. Thus, the outer wall 47 forms an annular recess around the ring 45, suitable for housing the collar 44. Advantageously, the first rim 471 and the second rim 472 have a radius greater than the sum of a radius of the channel 473 and the thickness of the collar 44. In other words, the channel 473 has a depth greater than the thickness of the collar 44 so that the collar 44 does not protrude radially from the ring 45.

[0063] Furthermore, the first rim 471 and the second rim 472 prevent any contact between the collar 44 and the external surface 262 of the housing 26 around which the cooling system 4 is positioned. The tube 41 is positioned as close as possible to the external surface 262 to improve cooling by the tubes 41, but only the first rim 471 and the second rim 472 can come into contact with the external surface 262, thus preventing metal-to-metal contact between the tube 41 or the collar 44 and the external surface 262.

[0064] Thus, the collar 44 is fixed to the support 43 and attaches the tube 41 to the support 43 by encircling the ring 45 with the channel 473 of the ring. The collar 44 is retained radially in the channel 473 of the ring 45 by its attachment to the support 43 and tangentially by the first rim 471 and the second rim 472 of the outer wall 47 of the ring 45.

[0065] The ring 45 comprises several angular portions of ring 45a, as illustrated by Figure 6. Such portions of ring 45a can thus be more easily replaced in case of defect or breakage because they do not require dismantling of the cooling system 4 of the low pressure turbine 241 but only the removal of the collar 44 surrounding the defective ring 45.

[0066] Each segment of ring 45a can have a central angle between 60° and 100°. The ring can thus encircle a portion between 240° and 300° of the tube 41. Therefore, the tube 41 is adequately protected from the collar 44 by the ring 45. Furthermore, the presence of three segments of ring 45a allows for isostatic positioning of the ring 45 around the tube 41, thus avoiding problems of over-constraint.

[0067] The collar 44 may include several lugs 441 for positioning the ring portions 45a around the tube 41. The lug 441 extends longitudinally from the collar so as to extend against the first rim 471 or the second rim 472 of an angular ring portion 45a, or between the first rims 471 or the second rims 472 of adjacent angular ring portions 45a. The lug 441 holds the angular ring portions 45a in position around the tube 41.

[0068] Furthermore, one of the lugs 441 is positioned on the collar 44 facing the support 41 and between one of the ring segments 45a and a fastening of the collar 44 to the support 41. This prevents a ring segment 45a from being present facing the support 41 between one of the ring segments 45a and a fastening of the collar 44 to the support 41. Indeed, at this point, the first and second ends of the collar are screwed together onto the support 43, thus forming an area of ​​the collar subjected to greater stress than the rest of the collar. The presence of a ring segment 45a in this area would cause excessive wear on the ring segment 45a. The presence of one of the lugs 441 on the collar 44 opposite the support 41 and between one of the portions of ring 45a and a fixing of the collar 44 to the support 41 therefore prevents excessive wear of a portion of ring 45a.The lug in question 441 may be wider than other lugs 441 depending on the width of the area to be avoided.

[0069] Benefits

[0070] The cooling system 4, extending around the low-pressure turbine 241, not only cools the casing 26 but also regulates the operating clearances between the turbine blades and the casing 26. As described previously, temperature changes in the casing 26 cause variations in the operating clearances between the turbine blades and the casing 26 due to the thermal expansion of the casing 26. These operating clearances between the blade tips and the casing 26 are crucial for the performance of the engine 2. Indeed, the smaller the clearances, the less flow bypasses the turbine blades and the distributors, and the better the efficiency of the low-pressure turbine 241. Consequently, cooling the casing 26 has a significant impact on the performance of the low-pressure turbine 242 and, therefore, on the engine 2.

[0071] The operating temperatures of the engine 2, and therefore of the casing 26, as well as vibrations require the use of metallic material to form the tubes 41 and the collars 44 of the retaining device 42 of the tubes 41.

[0072] The graphite ring 45, associated with each clamp 44, prevents direct contact between the clamp 44 and the tube 41. Indeed, contact between the clamp 44 and the tube 41 could cause damage or breakage of the tube 41 and / or the clamp 44, negatively affecting the cooling system 4 and consequently the operating clearances. The graphite withstands the operating temperatures of the housing 26 and effectively lubricates the contact between the tube 41 and the ring 45. In fact, the ring 45 forms a layer of worn graphite between the tube 41 and the ring 45, this layer preventing wear on the tube 41 and thus its deterioration.

[0073] Furthermore, the first rim 471 and the second rim 472 help to retain the collar 44 within the ring. In addition, the first rim 471 and the second rim 472 advantageously prevent contact between the tube 41 and the support 43, as well as between the tube 41 and the housing 26, and also between the collar 44 and the support 43 or the external surface 262.

[0074] The use of the graphite ring 45 is particularly advantageous when the clamp 44 and the tube 41 are made of metal. Indeed, contact between the metal clamp 44 and the metal tube 41 could generate significant wear on the clamp 44 and / or the tube 41. However, with the graphite ring 45, the clamp 44 and the tube 41 do not wear because it is the ring 45 that wears down and ensures lubricated contact through its wear.

[0075] The presence of three ring portions 45a, each intended to surround a portion of the tube 41, ensures isostaticity between the collar 44 and the tube 41.

[0076] A surround of a portion between 240° and 300° of the tube 41 by the ring 45 allows the tube 41 to be protected while allowing good positioning of the portions of ring 45a around the tube 41.

Claims

DEMANDS 1. A retaining device (42) for an air jet cooling tube of a turbomachine housing (26), the device comprising: - an external support (43) adapted to be positioned around a turbomachine housing (26), - a collar (44) adapted to surround a tube (41) and hang it on the support (43), - a graphite ring (45) intended to be positioned around the tube (41), between the collar (44) and the tube (41), the ring (45) comprising three ring portions (45a) intended to surround each a portion of the tube (41), the ring surrounding an angular portion between 240° inclusive and 300° inclusive of the circumference of the tube (41).

2. Retaining device (42) according to claim 1, in which the ring (45) has an annular shape comprising an outer wall (47), the outer wall (47) comprising a first annular rim (471), a second annular rim (472) and an annular channel (473) between the first rim (471) and the second rim, the outer wall (47) forming an annular recess suitable for housing the collar (44).

3. Retaining device (42) according to claim 2, wherein the first rim (471) and the second rim (472) comprise a radius of a dimension greater than the sum of a radius of the channel (473) and a thickness of the collar (44).

4. Retaining device (42) according to any one of claims 1 to 3, wherein each portion of ring (45a) has a central angle between 60° and 100°.

5. Retaining device (42) according to any one of claims 1 to 4, wherein the collar includes lugs (441) for positioning each portion of ring (45a) on the collar (44) around the tube (41).

6. Retaining device (42) according to claim 5, wherein one of the lugs (441) is positioned on the collar (44) facing the support (41) and between one of the ring portions (45a) and a fixing of the collar (44) to the support (41).

7. Retaining device (42) according to any one of claims 1 to 6, wherein the collar (44) is metallic.

8. A retaining device (42) according to any one of claims 1 to 7, the device comprising several clamps (44) and rings (45) adapted to retain the tube (41) on the support (43).

9. An air-jet cooling system (4) for a turbomachine housing (26), the system comprising: - a cooling tube (41) comprising holes adapted for injecting air onto a housing (26), - a tube (42) retaining device (41) around the housing (26) according to any one of claims 1 to 8, and wherein the collar (44) is positioned around the tube (41) and is fixed to the support (43), and the graphite ring (45) is positioned around the tube, between the collar (44) and the tube (41), the ring (45) comprising three ring portions (45a) intended to each surround a portion of the tube (41), the ring surrounding a portion between 240° and 300° of the tube (41).

10. Turbomachine assembly, comprising a turbomachine casing (26), and a cooling system (4) according to claim 9.

11. Turbomachine (2) of an aircraft comprising a turbomachine assembly according to claim 10.

12. Aircraft (100) comprising a cell and a turbomachine (2) according to claim 11, wherein the turbomachine (2) is fixed to the cell.

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